WorldWideScience

Sample records for valence electron concentration

  1. Investigation of structural, electronic and anisotropic elastic properties of Ru-doped WB{sub 2} compound by increased valence electron concentration

    Energy Technology Data Exchange (ETDEWEB)

    Surucu, Gokhan, E-mail: g_surucu@yahoo.com [Ahi Evran University, Department of Electric and Energy, 40100, Kirsehir (Turkey); Gazi University, Photonics Application and Research Center, 06500, Ankara (Turkey); Kaderoglu, Cagil [Ankara University, Department of Engineering Physics, 06100, Ankara (Turkey); Deligoz, Engin; Ozisik, Haci [Aksaray University, Department of Physics, 68100, Aksaray (Turkey)

    2017-03-01

    First principles density functional theory (DFT) calculations have been used to investigate the structural, anisotropic elastic and electronic properties of ruthenium doped tungsten-diboride ternary compounds (W{sub 1−x}Ru{sub x}B{sub 2}) for an increasing molar fraction of Ru atom from 0.1 to 0.9 by 0.1. Among the nine different compositions, W{sub 0.3}Ru{sub 0.7}B{sub 2} has been found as the most stable one due to the formation energy and band filling theory calculations. Moreover, the band structures and partial density of states (PDOS) have been computed for each x composition. After obtaining the elastic constants for all x compositions, the secondary results such as Bulk modulus, Young’s modulus, Poisson’s ratio, Shear modulus, and Vickers Hardness of polycrystalline aggregates have been derived and the relevant mechanical properties have been discussed. In addition, the elastic anisotropy has been visualized in detail by plotting the directional dependence of compressibility, Poisson ratio, Young’s and Shear moduli. - Highlights: • Effects of Ru substitution in WB{sub 2} using increased valence electron concentration. • Structural, electronic, mechanic and elastic properties for increasing Ru content. • Considered alloys are incompressible, brittle, stiffer and high hard materials.

  2. Valence electronic state density in thorium dioxide

    Directory of Open Access Journals (Sweden)

    Teterin Anton Yu.

    2008-01-01

    Full Text Available This work analyses the fine low energy (0-40 eV X-ray photoelectron spectra of ThO2, taking into account relativistic Xα-discrete variation electronic structure calculations for the ThO8 (D4h cluster reflecting thorium's close environment in ThO2. As a result, it was theoretically shown and experimentally confirmed that Th5f electrons in ThO2 can participate directly (~0.6 Th5f electrons in chemical bond formation.Th6p electrons were shown to be a significant part (~0.44 Th6p electrons not only of inner valence molecular orbitals, but to play a significant role in outer valence molecular orbitals formation, as well. Inner valence molecular orbitals composition and sequent order were established to belong to the binding energy range of 13 eV to 40 eV. The valence electronic state density in the range of 0-40 eV in ThO2 was also calculated. For the first time, these data allowed an interpretation of the fine X-ray photoelectron spectra (0-40 eV and high resolution O4,5(Th X-ray emition spectral structure (~60 - ~85 eV of ThO2.

  3. Teaching Valence Shell Electron Pair Repulsion (VSEPR) Theory

    Science.gov (United States)

    Talbot, Christopher; Neo, Choo Tong

    2013-01-01

    This "Science Note" looks at the way that the shapes of simple molecules can be explained in terms of the number of electron pairs in the valence shell of the central atom. This theory is formally known as valence shell electron pair repulsion (VSEPR) theory. The article explains the preferred shape of chlorine trifluoride (ClF3),…

  4. Positron annihilation with core and valence electrons

    CERN Document Server

    Green, D G

    2015-01-01

    $\\gamma$-ray spectra for positron annihilation with the core and valence electrons of the noble gas atoms Ar, Kr and Xe is calculated within the framework of diagrammatic many-body theory. The effect of positron-atom and short-range positron-electron correlations on the annihilation process is examined in detail. Short-range correlations, which are described through non-local corrections to the vertex of the annihilation amplitude, are found to significantly enhance the spectra for annihilation on the core orbitals. For Ar, Kr and Xe, the core contributions to the annihilation rate are found to be 0.55\\%, 1.5\\% and 2.2\\% respectively, their small values reflecting the difficulty for the positron to probe distances close to the nucleus. Importantly however, the core subshells have a broad momentum distribution and markedly contribute to the annihilation spectra at Doppler energy shifts $\\gtrsim3$\\,keV, and even dominate the spectra of Kr and Xe at shifts $\\gtrsim5$\\,keV. Their inclusion brings the theoretical ...

  5. Valence band electronic structure of Pd based ternary chalcogenide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Lohani, H. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India); Mishra, P. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Goyal, R.; Awana, V.P.S. [National Physical Laboratory(CSIR), Dr. K. S. Krishnan Road, New Delhi 110012 (India); Sekhar, B.R., E-mail: sekhar@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India)

    2016-12-15

    Highlights: • VB Photoemission study and DFT calculations on Pd based ternary superconductors are presented. • Nb{sub 2}Pd{sub 0.95}S{sub 5} shows a temperature dependent pseudogap. • VB spectral features of ternary superconductors are correlated to their structural geometry. - Abstract: We present a comparative study of the valence band electronic structure of Pd based ternary chalcogenide superconductors Nb{sub 2}Pd{sub 0.95}S{sub 5}, Ta{sub 2}Pd{sub 0.97}S{sub 6} and Ta{sub 2}Pd{sub 0.97}Te{sub 6} using experimental photoemission spectroscopy and density functional based theoretical calculations. We observe a qualitatively similarity between valence band (VB) spectra of Nb{sub 2}Pd{sub 0.95}S{sub 5} and Ta{sub 2}Pd{sub 0.97}S{sub 6}. Further, we find a pseudogap feature in Nb{sub 2}Pd{sub 0.95}S{sub 5} at low temperature, unlike other two compounds. We have correlated the structural geometry with the differences in VB spectra of these compounds. The different atomic packing in these compounds could vary the strength of inter-orbital hybridization among various atoms which leads to difference in their electronic structure as clearly observed in our DOS calculations.

  6. High-Resolution Conversion Electron Spectroscopy of Valence Electron Configurations (CESVEC) in Solids

    CERN Multimedia

    2002-01-01

    First measurements with the Zurich $\\beta$-spectrometer on sources from ISOLDE have demonstrated that high resolution spectroscopy of conversion electrons from valence shells is feasible.\\\\ \\\\ This makes possible a novel type of electron spectroscopy (CESVEC) on valence-electron configurations of tracer elements in solids. Thus the density of occupied electron states of impurities in solids has been measured for the first time. Such data constitute a stringent test of state-of-the-art calculations of impurity properties. Based on these results, we are conducting a systematic investigation of impurities in group IV and III-V semiconductors.

  7. Electron momentum spectroscopy study of amantadine: binding energy spectra and valence orbital electron density distributions

    Science.gov (United States)

    Litvinyuk, I. V.; Zheng, Y.; Brion, C. E.

    2000-11-01

    The electron binding energy spectrum and valence orbital electron momentum density distributions of amantadine (1-aminoadamantane), an important anti-viral and anti-Parkinsonian drug, have been measured by electron momentum spectroscopy. Theoretical momentum distributions, calculated at the 6-311++G** and AUG-CC-PVTZ levels within the target Hartree-Fock and also the target Kohn-Sham density functional theory approximations, show good agreement with the experimental results. The results for amantadine are also compared with those for the parent molecule, adamantane, reported earlier (Chem. Phys. 253 (2000) 41). Based on the comparison tentative assignments of the valence region ionization bands of amantadine have been made.

  8. The stabilities and electron structures of Al-Mg clusters with 18 and 20 valence electrons

    Science.gov (United States)

    Yang, Huihui; Chen, Hongshan

    2017-07-01

    The spherical jellium model predicts that metal clusters having 18 and 20 valence electrons correspond to the magic numbers and will show specific stabilities. We explore in detail the geometric structures, stabilities and electronic structures of Al-Mg clusters containing 18 and 20 valence electrons by using genetic algorithm combined with density functional theories. The stabilities of the clusters are governed by the electronic configurations and Mg/Al ratios. The clusters with lower Mg/Al ratios are more stable. The molecular orbitals accord with the shell structures predicted by the jellium model but the 2S level interweaves with the 1D levels and the 2S and 1D orbitals form a subgroup. The clusters having 20 valence electrons form closed 1S21P61D102S2 shells and show enhanced stability. The Al-Mg clusters with a valence electron count of 18 do not form closed shells because one 1D orbital is unoccupied. The ionization potential and electron affinity are closely related to the electronic configurations; their values are determined by the subgroups the HOMO or LUMO belong to. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80042-9

  9. Time-resolved imaging of purely valence-electron dynamics during a chemical reaction

    DEFF Research Database (Denmark)

    Hockett, Paul; Bisgaard, Christer Z.; Clarkin, Owen J.

    2011-01-01

    the non-adiabatic photodissociation of carbon disulphide demonstrate how the purely electronic rearrangements of the valence electrons can be projected from inherently coupled electronic-vibrational dynamics. Combined with ongoing efforts in molecular frame alignment(20) and orientation(21,22), TRMFPADs...... offer the promise of directly imaging valence-electron dynamics during molecular processes without involving the use of strong, highly perturbing laser fields(23)....

  10. The New Resonating Valence Bond Method for Ab-Initio Electronic Simulations

    OpenAIRE

    Sorella, Sandro; Zen, Andrea

    2013-01-01

    The Resonating Valence Bond theory of the chemical bond was introduced soon after the discovery of quantum mechanics and has contributed to explain the role of electron correlation within a particularly simple and intuitive approach where the chemical bond between two nearby atoms is described by one or more singlet electron pairs. In this chapter Pauling's resonating valence bond theory of the chemical bond is revisited within a new formulation, introduced by P.W. Anderson after the discover...

  11. Reactivity of seventeen- and nineteen-valence electron complexes in organometallic chemistry

    Science.gov (United States)

    Stiegman, Albert E.; Tyler, David R.

    1986-01-01

    A guideline to the reactivity of 17- and 19-valence electron species in organometallic chemistry is proposed which the authors believe will supersede all others. The thesis holds that the reactions of 17-electron metal radicals are associatively activated with reactions proceeding through a 19-valence electron species. The disparate reaction chemistry of the 17-electron metal radicals are unified in terms of this associative reaction pathway, and the intermediacy of 19-valence electron complexes in producing the observed products is discussed. It is suggested that related associatively activated pathways need to be considered in some reactions that are thought to occur by more conventional routes involving 16- and 18-electron intermediates. The basic reaction chemistry and electronic structures of these species are briefly discussed.

  12. Valence electron energy-loss spectroscopy in monochromated scanning transmission electron microscopy.

    Science.gov (United States)

    Erni, Rolf; Browning, Nigel D

    2005-10-01

    With the development of monochromators for (scanning) transmission electron microscopes, valence electron energy-loss spectroscopy (VEELS) is developing into a unique technique to study the band structure and optical properties of nanoscale materials. This article discusses practical aspects of spatially resolved VEELS performed in scanning transmission mode and the alignments necessary to achieve the current optimum performance of approximately 0.15 eV energy resolution with an electron probe size of approximately 1 nm. In particular, a collection of basic concepts concerning the acquisition process, the optimization of the energy resolution, the spatial resolution and the data processing are provided. A brief study of planar defects in a Y(1)Ba(2)Cu(3)O(7-)(delta) high-temperature superconductor illustrates these concepts and shows what kind of information can be accessed by VEELS.

  13. The electronic properties of mixed valence hydrated europium chloride thin film.

    Science.gov (United States)

    Silly, M G; Charra, F; Lux, F; Lemercier, G; Sirotti, F

    2015-07-28

    We investigate the electronic properties of a model mixed-valence hydrated chloride europium salt by means of high resolution photoemission spectroscopy (HRPES) and resonant photoemission spectroscopy (RESPES) at the Eu 3d → 4f and 4d → 4f transitions. From the HRPES spectra, we have determined that the two europium oxidation states are homogeneously distributed in the bulk and that the hydrated salt film is exempt from surface mixed valence transition. From the RESPES spectra, the well separated resonant contributions characteristic of divalent and trivalent europium species (4f(6) and 4f(7) final states, respectively) are accurately extracted and quantitatively determined from the resonant features measured at the two edges. The partial absorption yield spectra, obtained by integrating the photoemission intensity in the valence-band region, can be well reproduced by atomic multiplet calculation at the M(4,5) (3d-4f) absorption edge and by an asymmetric Fano-like shape profile at the N(4,5) (4d-4f) absorption edge. The ratio of Eu(2+) and Eu(3+) species measured at the two absorption edges matches with the composition of the mixed valence europium salt as determined chemically. We have demonstrated that the observed spectroscopic features of the mixed valence salt are attributed to the mixed-valence ground state rather than surface valence transition. HRPES and RESPES spectra provide reference spectra for the study of europium salts and their derivatives.

  14. Determining binding energies of valence-band electrons in insulators and semiconductors via lanthanide spectroscopy

    NARCIS (Netherlands)

    Dorenbos, P.

    2013-01-01

    Models and methods to determine the absolute binding energy of 4f-shell electrons in lanthanide dopants will be combined with data on the energy of electron transfer from the valence band to a lanthanide dopant. This work will show that it provides a powerful tool to determine the absolute binding

  15. Determination of conduction and valence band electronic structure ...

    Indian Academy of Sciences (India)

    Electronic structures of rutile and anatase polymorph of TiO2 were determined by resonant inelastic X-ray scattering measurements and FEFF9.0 calculations. Difference between crystalline structures led to shifts in the rutile Ti -band to lower energy with respect to anatase, i.e., decrease in band gap. Anatase possesses ...

  16. Determination of conduction and valence band electronic structure ...

    Indian Academy of Sciences (India)

    insufficient to study in-depth unoccupied states of investigated materials because it overlooks the shallow traps. Keywords. Photo-catalysis; high-resolution RIXS; electronic structure. 1. Introduction. Photocatalysis is an emerging field that offers poten- tial to address some of the energy and waste manage- ment challenges.

  17. Differences between problem and nonproblem gamblers in subjective arousal and affective valence amongst electronic gaming machine players.

    Science.gov (United States)

    Brown, Stephen L; Rodda, Simone; Phillips, James G

    2004-12-01

    Arousal-based theories of gambling suggest that excitement gained from gambling reinforces further gambling behavior. However, recent theories of emotion conceptualize mood as comprising both arousal and valence dimensions. Thus, excitement comprises arousal with positive valence. We examined self-reported changes in arousal and affective valence in 27 problem and 40 nonproblem gamblers playing electronic gaming machines (EGMs). Problem gamblers reported greater arousal increases after gambling and increases in negative valence if they lost. This accords poorly with an excitement-based explanation of problem gambling.

  18. Electronic structure and thermoelectric properties of half-Heusler compounds with eight electron valence count—KScX (X = C and Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Ciftci, Yasemin O. [Department of Physics, Gazi University, Teknikokullar, Ankara 06500 (Turkey); Mahanti, Subhendra D. [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)

    2016-04-14

    Electronic band structure and structural properties of two representative half-Heusler (HH) compounds with 8 electron valence count (VC), KScC and KScGe, have been studied using first principles methods within density functional theory and generalized gradient approximation. These systems differ from the well studied class of HH compounds like ZrNiSn and ZrCoSb which have VC = 18 because of the absence of d electrons of the transition metal atoms Ni and Co. Electronic transport properties such as Seebeck coefficient (S), electrical conductivity (σ), electronic thermal conductivity (κ{sub e}) (the latter two scaled by electronic relaxation time), and the power factor (S{sup 2}σ) have been calculated using semi-classical Boltzmann transport theory within constant relaxation time approximation. Both the compounds are direct band gap semiconductors with band extrema at the X point. Their electronic structures show a mixture of heavy and light bands near the valance band maximum and highly anisotropic conduction and valence bands near the band extrema, desirable features of good thermoelectric. Optimal p- or n-type doping concentrations have been estimated based on thermopower and maximum power factors. The optimum room temperature values of S are ∼1.5 times larger than that of the best room temperature thermoelectric Bi{sub 2}Te{sub 3}. We also discuss the impact of the band structure on deviations from Weidemann-Franz law as one tunes the chemical potential across the band gap.

  19. Determining binding energies of valence-band electrons in insulators and semiconductors via lanthanide spectroscopy

    Science.gov (United States)

    Dorenbos, Pieter

    2013-01-01

    Models and methods to determine the absolute binding energy of 4f-shell electrons in lanthanide dopants will be combined with data on the energy of electron transfer from the valence band to a lanthanide dopant. This work will show that it provides a powerful tool to determine the absolute binding energy of valence band electrons throughout the entire family of insulator and semiconductor compounds. The tool will be applied to 28 fluoride, oxide, and nitride compounds providing the work function and electron affinity together with the location of the energy levels of all divalent and all trivalent lanthanide dopants with an accuracy that surpasses that of traditional methods like photoelectron spectroscopy. The 28 compounds were selected to demonstrate how work function and electron affinity change with composition and structure, and how electronic structure affects the optical properties of the lanthanide dopants. Data covering more than 1000 different halide (F, Cl, Br, I), chalcogenide (O, S, Se), and nitride compounds are available in the archival literature enabling us to routinely establish work function and electron affinity for this much wider collection of compounds.

  20. Valence electronic structure of the indene molecule: Experiment vs. GW calculations

    Energy Technology Data Exchange (ETDEWEB)

    Umari, P.; Stenuit, G. [CNR-IOM DEMOCRITOS Theory Elettra Group, Basovizza, Trieste (Italy); Castellarin-Cudia, C.; Feyer, V.; Di Santo, G.; Goldoni, A. [Sincrotrone Trieste S.C.p.A., Basovizza, Trieste (Italy); Borghetti, P.; Sangaletti, L. [Dipartimento di Matematica e Fisica, Universita Cattolica del Sacro Cuore, Brescia (Italy)

    2011-04-15

    We investigate the valence electronic properties in the gas phase of the indene molecule, which is one of the simplest polycyclic aromatic hydrocarbons, with photoemission spectroscopy using synchrotron light and through first-principles calculations using a many-body perturbation theory GW approach. We found an excellent agreement between theory and experiment. This allows us to assign to the peaks appearing in the photoemission spectrum the calculated molecular orbitals. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Valence electronic structure of cobalt phthalocyanine from an optimally tuned range-separated hybrid functional

    Science.gov (United States)

    Brumboiu, Iulia Emilia; Prokopiou, Georgia; Kronik, Leeor; Brena, Barbara

    2017-07-01

    We analyse the valence electronic structure of cobalt phthalocyanine (CoPc) by means of optimally tuning a range-separated hybrid functional. The tuning is performed by modifying both the amount of short-range exact exchange (α ) included in the hybrid functional and the range-separation parameter (γ ), with two strategies employed for finding the optimal γ for each α . The influence of these two parameters on the structural, electronic, and magnetic properties of CoPc is thoroughly investigated. The electronic structure is found to be very sensitive to the amount and range in which the exact exchange is included. The electronic structure obtained using the optimal parameters is compared to gas-phase photo-electron data and GW calculations, with the unoccupied states additionally compared with inverse photo-electron spectroscopy measurements. The calculated spectrum with tuned γ , determined for the optimal value of α = 0.1 , yields a very good agreement with both experimental results and with GW calculations that well-reproduce the experimental data.

  2. Electronic structure of InTe, SnAs and PbSb: Valence-skip compound or not?

    Energy Technology Data Exchange (ETDEWEB)

    Hase, Izumi, E-mail: i.hase@aist.go.jp [National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba 305-8568 (Japan); Yasutomi, Kouki [Graduate School of Pure and Applied Science, Univ. of Tsukuba, Tsukuba, 305-8571 (Japan); Yanagisawa, Takashi; Odagiri, Kousuke [National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba 305-8568 (Japan); Nishio, Taichiro [Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601 (Japan)

    2016-08-15

    Highlights: • We calculated the electronic structure of InTe, SnAs and PbSb from first principles. • Obtained tight-binding parameters of InTe are close to those of BaBiO3, which suggests that their electronic properties are also alike. • InTe is favorable to emerge valence skip, while PbSb is not favorable for it. SnAs is between the two. • Our findings well agree with the experimental results. - Abstract: InTe, SnAs and PbSb formally have unusual valence states, In{sup 2+}, Sn{sup 3+} and Pb{sup 3+}. All of them have B1 crystal structure at some pressure range. They are candidates of the valence-skip compound, which may have negative effective Coulomb interaction U{sub eff} < 0. Negative-U Hubbard model is known to show charge-density wave or superconductivity in some parameter region. In fact, SnAs becomes superconducting at ambient pressure. InTe has a kind of charge-density wave at ambient pressure, and it becomes superconducting at high pressure. We investigated their electronic structures by ab-initio calculations, and calculated the number of s-electrons at the cation site. We found that InTe is favorable to emerge valence skip, while PbSb is not favorable for valence skip. SnAs is between these two. These findings well agree with the experimental results.

  3. Electron spectroscopy study of the oxidation of a Zr-Fe getter. Pt. 2; Valence states

    Energy Technology Data Exchange (ETDEWEB)

    Puppin, E.; Braicovich, L.; Michelis, B. de; Vavassori, P.; Vescovo, E. (Ist. di Fisica, Politecnico di Milano (Italy))

    1992-03-15

    The valence electron states of a Zr-Fe getter having Zr{sub 2}Fe as majority component (80% of the total volume) and their evolution upon oxidation at room tempererature are studied with direct photoemission (h{nu}=21.2 and 40.8 eV) and inverse photoemission (isochromats in the range 12-21 eV). In the clean getter direct photoemission is mostly sensitive to Fe-derived states and inverse photoemission to Zr-derived states. Direct photoemission shows the modification of oxygen-p-derived states in the suboxide-oxide transition and the effect of Fe-oxygen interaction with a depletion of Fe d states near the Fermi level. Inverse photoemission shows a progressive localization of the Zr d states upon oxidation. (orig.).

  4. Understanding valence-shell electron-pair repulsion (VSEPR) theory using origami molecular models

    Science.gov (United States)

    Endah Saraswati, Teguh; Saputro, Sulistyo; Ramli, Murni; Praseptiangga, Danar; Khasanah, Nurul; Marwati, Sri

    2017-01-01

    Valence-shell electron-pair repulsion (VSEPR) theory is conventionally used to predict molecular geometry. However, it is difficult to explore the full implications of this theory by simply drawing chemical structures. Here, we introduce origami modelling as a more accessible approach for exploration of the VSEPR theory. Our technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer simulation or commercial three-dimensional modelling kits. This method can be implemented in chemistry education at both the high school and university levels. We discuss the example of a simple molecular structure prediction for ammonia (NH3). Using the origami model, both molecular shape and the scientific justification can be visualized easily. This ‘hands-on’ approach to building molecules will help promote understanding of VSEPR theory.

  5. Quantitative analysis of Li distributions in battery material Li1-xFePO4 using Fe M2,3-edge and valence electron energy loss spectra.

    Science.gov (United States)

    Kobayashi, Shunsuke; Fisher, Craig A J; Kuwabara, Akihide; Ukyo, Yoshio; Ikuhara, Yuichi

    2017-08-01

    The spatial distribution of Li ions in a lithium iron phosphate (Li1-xFePO4) single crystal after chemical delithiation is quantitatively investigated using Fe M2,3-edge and valence electron energy loss (EEL) spectroscopy techniques. Li contents between those of end-member compositions LiFePO4 and FePO4 are found to correspond to reproducible changes in Fe M2,3-edge and valence EEL spectra across an interface between LiFePO4 and FePO4 regions. Quantitative analysis of these changes is used to estimate the local valence states of Fe ions, from which the Li concentration in the intermediate phase can be deduced. The faster recording time for valence EEL spectra than Fe M2,3-edge spectra makes measurement of the former a more efficient and reproducible means of estimating Li distributions. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Spin-dependent electron-phonon coupling in the valence band of single-layer WS2

    DEFF Research Database (Denmark)

    Hinsche, Nicki Frank; Ngankeu, Arlette S.; Guilloy, Kevin

    2017-01-01

    The absence of inversion symmetry leads to a strong spin-orbit splitting of the upper valence band of semiconducting single-layer transition-metal dichalchogenides such as MoS2 or WS2. This permits a direct comparison of the electron-phonon coupling strength in states that only differ by their spin....... Here, the electron-phonon coupling in the valence band maximum of single-layer WS2 is studied by first-principles calculations and angle-resolved photoemission. The coupling strength is found to be drastically different for the two spin-split branches, with calculated values of λK=0.0021 and 0.......40 for the upper and lower spin-split valence band of the freestanding layer, respectively. This difference is somewhat reduced when including scattering processes involving the Au(111) substrate present in the experiment but it remains significant, in good agreement with the experimental results....

  7. Authentic Assessment Tool for the Measurement of Students' Understanding of the Valence Shell Electron Pair Repulsion Theory

    Science.gov (United States)

    Wuttisela, Karntarat

    2017-01-01

    There are various types of instructional media related to Valence Shell Electron Pair Repulsion (VSEPR) but there is a lack of diversity of resources devoted to assessment. This research presents an assessment and comparison of students' understanding of VSEPR theory before and after tuition involving the use of the foam molecule model (FMM) and…

  8. Introducing Students to Inner Sphere Electron Transfer Concepts through Electrochemistry Studies in Diferrocene Mixed-Valence Systems

    Science.gov (United States)

    Ventura, Karen; Smith, Mark B.; Prat, Jacob R.; Echegoyen, Lourdes E.; Villagran´, Dino

    2017-01-01

    We have designed a 4 h physical chemistry laboratory to introduce upper division students to electrochemistry concepts, including mixed valency and electron transfer (ET), using cyclic and differential pulse voltammetries. In this laboratory practice, students use a ferrocene dimer consisting of two ferrocene centers covalently bonded through a…

  9. Studies on the valence electronic structure of Fe and Ni in FexNi1−x ...

    Indian Academy of Sciences (India)

    Studies on the valence electronic structure of Fe and Ni in FexNi1−x alloys. D K BASA1,∗. , S RAJ2, H C PADHI2, M POLASIK3 and F PAWLOWSKI3. 1Department of Physics, Utkal University, Bhubaneswar 751 004, India. 2Institute of Physics, Bhubaneswar 751 005, India. 3Faculty of Chemistry, Nicholas Copernicus ...

  10. XUV-initiated high harmonic generation: driving inner valence electrons using below-threshold-energy XUV light

    CERN Document Server

    Brown, A C

    2016-01-01

    We propose a novel scheme for resolving the contribution of inner- and outer-valence electrons in XUV-initiated high-harmonic generation in neon. By probing the atom with a low energy (below the 2s ionisation threshold) ultrashort XUV pulse, the 2p electron is steered away from the core, while the 2s electron is enabled to describe recollision trajectories. By selectively suppressing the 2p recollision trajectories we can resolve the contribution of the 2s electron to the high-harmonic spectrum. We apply the classical trajectory model to account for the contribution of the 2s electron, which allows for an intuitive understanding of the process.

  11. Explicitly correlated N-electron valence state perturbation theory (NEVPT2-F12)

    Science.gov (United States)

    Guo, Yang; Sivalingam, Kantharuban; Valeev, Edward F.; Neese, Frank

    2017-08-01

    In this work, explicitly correlated second order N-electron valence state perturbation theory (NEVPT2-F12) has been derived and implemented for the first time. The NEVPT2-F12 algorithm presented here is based on a fully internally contracted wave function and includes the correction of semi-internal excitation subspaces. The algorithm exploits the resolution of identity (RI) approximation to improve the computational efficiency. The overall O(N5) scaling of the computational effort is documented. In Sec. III, the dissociation processes of diatomic molecules and the singlet-triplet gap of several systems are studied. For all relative energies studied in this work, the errors with respect to the complete basis set (CBS) limit for the NEVPT2-F12 method are within 1 kcal/mol. For moderately sized active spaces, the computational cost of a RI-NEVPT2-F12 correlation energy calculation for each root is comparable to a closed-shell RI-MP2-F12 calculation on the same system.

  12. Determination of Chromium Valence Over the Range Cr(0)-Cr(VI) by Electron Energy Loss Spectroscopy

    Science.gov (United States)

    2006-01-01

    be of Cr (VI): Cr (V) [14,40-45] and Cr (IV) [46]. To fully altered by microbes [11-13], green algae [14], higher plants understand the geochemistry of Cr ... Cr (III) by bacteria [42,44,45] and Further, nearly all mineralized Cr in the terrestrial crust is green algae [14], reacts with diphenylcarbazide to...Determination of chromium valence over the range Cr (O)- Cr (VI) by electron energy loss spectroscopy Tyrone L. Daultona , Brenda J. Littleb ’Marine

  13. Electronic structure and positron annihilation in alkali metals: isolation of ionic core contribution and valence high-momentum components

    Energy Technology Data Exchange (ETDEWEB)

    Sob, M. (Ceskoslovenska Akademie Ved, Brno. Ustav Fyzikalni Metalurgie)

    1985-01-01

    Momentum densities of annihilation pairs from valence as well as from ionic core electrons in alkali metals are calculated ab initio and compared with the experimental results. It is shown that the valence high-momentum components constitute a great deal (23-34% in Na-Cs and probably even more in Li) of the Gaussian part of the angular correlation curves. The average core enhancement factor ..gamma..sub(c) ranges from 1.5 (Li) to 7.1 (Cs) and may be well expressed by a logarithmic function of ionic core polarizability. The presented values of ..gamma..sub(c) are much higher than the core enhancement factors in the high-momentum (> approx. 15 mrad) region which, according to the recent theory of Bonderup, Andersen and Lowy, should not be very different from unity.

  14. Effects of electrolyte concentration and counterion valence on the microstructural flow regimes in dilute cetyltrimethylammonium tosylate micellar solutions.

    Science.gov (United States)

    Tepale, N; Macías, E R; Bautista, F; Puig, J E; Manero, O; Gradzielski, M; Escalante, J I

    2011-11-15

    The shear thickening behavior and the transition to shear thinning are examined in dilute cetyltrimethylammonium tosylate (CTAT) micellar solutions as a function of surfactant concentration and ionic strength using electrolytes with different counterion valence. Newtonian behavior at low shear rates, followed by shear thickening and shear thinning at higher shear rates, are observed at low and intermediate surfactant and electrolyte concentrations. Shear thickening diminishes with increasing surfactant concentration and ionic strength. At higher surfactant or electrolyte concentration, only a Newtonian region followed by shear thinning is detected. A generalized flow diagram indicates two controlling regimes: one in which electrostatic screening dominates and induces micellar growth, and another, at higher electrolyte and surfactant concentrations, where chemical equilibrium among electrolyte and surfactant counterions controls the rheological behavior by modifying micellar breaking and reforming. Analysis of the shear thickening behavior reveals that not only a critical shear rate is required for shear thickening, but also a critical deformation, which appears to be unique for all systems examined, within experimental error. Moreover, a superposition of the critical shear rate for shear thickening with surfactant and electrolyte concentration is reported. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Mapping of valence energy losses via energy-filtered annular dark-field scanning transmission electron microscopy.

    Science.gov (United States)

    Gu, Lin; Sigle, Wilfried; Koch, Christoph T; Nelayah, Jaysen; Srot, Vesna; van Aken, Peter A

    2009-08-01

    The advent of electron monochromators has opened new perspectives on electron energy-loss spectroscopy at low energy losses, including phenomena such as surface plasmon resonances or electron transitions from the valence to the conduction band. In this paper, we report first results making use of the combination of an energy filter and a post-filter annular dark-field detector. This instrumental design allows us to obtain energy-filtered (i.e. inelastic) annular dark-field images in scanning transmission electron microscopy of the 2-dimensional semiconductor band-gap distribution of a GaN/Al(45)Ga(55)N structure and of surface plasmon resonances of silver nanoprisms. In comparison to other approaches, the technique is less prone to inelastic delocalization and relativistic artefacts. The mixed contribution of elastic and inelastic contrast is discussed.

  16. Topology of electron charge density for chemical bonds from valence bond theory: a probe of bonding types.

    Science.gov (United States)

    Zhang, Lixian; Ying, Fuming; Wu, Wei; Hiberty, Philippe C; Shaik, Sason

    2009-01-01

    To characterize the nature of bonding we derive the topological properties of the electron charge density of a variety of bonds based on ab initio valence bond methods. The electron density and its associated Laplacian are partitioned into covalent, ionic, and resonance components in the valence bond spirit. The analysis provides a density-based signature of bonding types and reveals, along with the classical covalent and ionic bonds, the existence of two-electron bonds in which most of the bonding arises from the covalent-ionic resonance energy, so-called charge-shift bonds. As expected, the covalent component of the Laplacian at the bond critical point is found to be largely negative for classical covalent bonds. In contrast, for charge-shift bonds, the covalent part of the Laplacian is small or positive, in agreement with the weakly attractive or repulsive character of the covalent interaction in these bonds. On the other hand, the resonance component of the Laplacian is always negative or nearly zero, and it increases in absolute value with the charge-shift character of the bond, in agreement with the decrease of kinetic energy associated with covalent-ionic mixing. A new interpretation of the topology of the total density at the bond critical point is proposed to characterize covalent, ionic, and charge-shift bonding from the density point of view.

  17. Microscopic Examinations of Co Valences and Spin States in Electron-Doped LaCoO3

    Science.gov (United States)

    Tomiyasu, Keisuke; Koyama, Syun-Ichi; Watahiki, Masanori; Sato, Mika; Nishihara, Kazuki; Takahashi, Yuki; Onodera, Mitsugi; Iwasa, Kazuaki; Nojima, Tsutomu; Nojiri, Hiroyuki; Okamoto, Jun; Huang, Di-Jing; Yamasaki, Yuuichi; Nakao, Hironori; Murakami, Youichi

    2016-09-01

    We studied the Co valences and spin states in electron-doped LaCo1-yTeyO3 by measuring X-ray absorption spectra and electron spin resonance. The low-temperature insulating state involves the low-spin Co3+ state (S = 0) and the high-spin Co2+ state, where the latter is described by g = 3.8 and jeff = 1/2. The results, in concurrence with the electron-hole asymmetry confirmed in the electrical resistivity, coincide with the spin-blockade phenomenon in this system. Furthermore, we discuss the g factor in terms of the strong covalent-bonding nature and consider multiple origins of this phenomenon.

  18. Electronic structure of SnF{sub 3}: An example of valence skipper which forms charge density wave

    Energy Technology Data Exchange (ETDEWEB)

    Hase, I., E-mail: i.hase@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568 (Japan); Yanagisawa, T. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568 (Japan); Kawashima, K. [IMRA Material R& D Co., LTD., Kariya, Aichi 448-0032 (Japan)

    2016-11-15

    Highlights: • We calculated the electronic structure of SnF{sub 3} and BaBiO{sub 3} from first principles. • As for SnF{sub 3}, charge-density-wave (CDW) is found, which agrees with the experiment. • As for BaBiO{sub 3}, CDW is not found, contrary to the experiment. • We conclude that the CDW is hard in SnF{sub 3} and is soft in BaBiO{sub 3}. - Abstract: In the present study we calculated the electronic structure of the valence skipping compound SnF{sub 3} and BaBiO{sub 3} from first-principles. We confirmed that the charge-density-wave (CDW) is formed in SnF{sub 3}, and the Sn atoms in two crystallographic different sites take the valence Sn{sup 2+} and Sn{sup 4+}. Structure optimization study reveals that this CDW is stable, though the atomic position is slightly different from the experimental data. This behavior is in contrast with the case of BaBiO{sub 3}, where the structure optimization leads to the uniform state, which means that two Bi sites are equivalent. The CDW state is hard in SnF{sub 3}, which means that the CDW gap is large enough and it is difficult to melt this CDW order.

  19. A theoretical and (e,2e) experimental investigation into the complete valence electronic structure of (1.1.1) propellane

    Energy Technology Data Exchange (ETDEWEB)

    Adcock, W.; Clark, C.I. [Flinders Univ. of South Australia, Bedford Park, SA (Australia); Brunger, M.J.; McCarthy, I.E. [Flinders Univ. of South Australia, Bedford Park, SA (Australia). School of Physical Sciences; Michalewicz, M.T. [CSIRO, Carlton, VIC (Australia). Division of Information Technology; Von Niessen, W. [Technische Univ., Braunschweig (Germany). Institute fur Physikalische and Theoretische Chemie; Weigold, E. [Australian National Univ., Canberra, ACT (Australia). Inst. of Advanced Studies; Winkler, D.A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, VIC (Australia). Div. of Chemical Physics

    1996-08-01

    The first comprehensive electronic structural study of the complete valence shell of [1.1.1] propellane is reported. Binding energy spectra were measured in the energy regime 3.5-46.5 eV over a range of different target electron momentum so that individual orbital momentum profiles could also be determined. These binding energy spectra were collected using an energy dispersive multichannel electron momentum spectrometer at a total energy of 1000 eV, with a coincidence energy resolution of 1.38 eV and a momentum resolution of about 0.1 a.u. The experimental orbital electron momentum profiles are compared with those calculated in the plane wave impulse approximation (PWIA) using both a triple zeta plus polarisation level SCF wavefunction and a further 13 basis sets as calculated using Density Functional Theory (DFT). A critical comparison between the experimental an theoretical momentum distributions (MDs) allows to determine the optimum wavefunction for [1.1.1]propellane. In general, the level of agreement between the experimental and theoretical MDs for the optimum wavefunction for all of the respective valence orbitals was very good. The determination of this wavefunction then allowed to derive the chemically interesting molecular properties of [1.1.1]propellane. These include infrared spectra, bond lengths, bond orders, electron densities and many others. A summary of these results and a comparison of them with the previous results of other workers is presented with the level of agreement typically being good. In particular, the existence of the C1-C3 bridging bond with a bond order of 0.70 was confirmed. 59 refs., 4 tabs., 11 figs.

  20. Valence-band spectra and electronic structure of CuFeO2

    Science.gov (United States)

    Galakhov, V. R.; Poteryaev, A. I.; Kurmaev, E. Z.; Anisimov, V. I.; Bartkowski, St.; Neumann, M.; Lu, Z. W.; Klein, B. M.; Zhao, Tong-Rong

    1997-08-01

    The delafossite-type CuFeO2 single crystal was studied by means of x-ray emission and x-ray photoelectron spectroscopy. The valence state of Cu ions was found to be 1+, whereas Fe ions were found to be trivalent in the high-spin S=5/2 state. The x-ray emission (Cu Lα, Fe Lα, and O Kα) and photoelectron spectra were compared to the results of the local spin density approximation (LSDA) (full-potential linearized augmented plane wave method and linearized muffin-tin orbitals in atomic sphere approximation method) and LSDA+U calculations. It is found that the maximum of the Cu 3d state distribution is localized closer to the Fermi level than that of the Fe 3d states. The LSDA calculations contradict the experimental results and do not give a correct description of the Cu and Fe 3d positions relative to the Fermi level, and incorrectly predict metallic behaviors (semiconductor observed) and give qualitatively incorrect magnetic properties of CuFeO2. The LSDA+U calculations give a much better agreement with the observed valence-band structure, the measured electrical, and the magnetic properties.

  1. Strong dependence of shake probability on valence electron state for the inner-shell ionization of atoms

    Energy Technology Data Exchange (ETDEWEB)

    Kupliauskiene, A [Institute of Theoretical Physics and Astronomy of Vilnius University, A Gostauto 12, 2600 Vilnius (Lithuania); Glemza, K [Vilnius University, Sauletekio 9, Vilnius (Lithuania)

    2002-11-28

    The probability of the shaking process accompanying inner-shell ionization (expressed as the square of the overlap integrals of valence electron radial orbitals in the initial and final states) is calculated for a number of second- and third-row atoms and singly and doubly charged ions (in the excited states of n{sub 0} l{sub 0}{sup N} nl (3{<=}n{<=}9, 0{<=}l{<=}3)). Enormous differences are found for the low-excited n s and n p states between shake probabilities that are calculated using numerical solutions of Hartree-Fock equations and hydrogenic radial orbitals (with an effective nuclear charge and with an effective principal quantum number obtained from experimental binding energies). The results can be a useful guide in the search for strong relaxation effects in the Auger decay and inner-shell ionization of excited atoms and ions by photons and electrons as well as in sudden-perturbation approximation calculations.

  2. Ion correlations in nanofluidic channels: effects of ion size, valence, and concentration on voltage- and pressure-driven currents.

    Science.gov (United States)

    Hoffmann, Jordan; Gillespie, Dirk

    2013-01-29

    The effects of ion-ion and ion-wall correlations in nanochannels are explored, specifically how they influence voltage- and pressure-driven currents and pressure-to-voltage energy conversion. Cations of different diameters (0.15, 0.3, and 0.9 nm) and different valences (+1, +2, and +3) at concentrations ranging from 10(-6) M to 1 M are considered in 50-nm- and 100-nm-wide nanoslits with wall surface charges ranging from 0 C/m(2) to -0.3 C/m(2). These parameters are typical of nanofluidic devices. Ion correlations have significant effects on device properties over large parts of this parameter space. These effects are the result of ion layering (oscillatory concentration profiles) for large monovalent cations and charge inversion (more cations in the first layer near the wall than necessary to neutralize the surface charge) for the multivalent cations. The ions were modeled as charged, hard spheres using density functional theory of fluids, and current was computed with the Navier-Stokes equations with two different no-slip conditions.

  3. Effect of salt valency and concentration on structure and thermodynamic behavior of anionic polyelectrolyte Na+-polyethacrylate aqueous solution.

    Science.gov (United States)

    Sappidi, Praveenkumar; Natarajan, Upendra

    2016-11-01

    The intermolecular structure and solvation enthalpy of anionic polyelectrolyte atactic Na+-polyethacrylate (PEA) in aqueous solution, as a function of added salt concentration C s (dilute to concentrated) and valency (NaCl versus CaCl2), were investigated via molecular dynamics simulations with explicit-ion-solvent and atomistic polymer description. An increase in C s leads to a decrease in α, which stabilizes to a constant value beyond critical C s. A significant reduction in R g in the presence of CaCl2 salt was observed, due to ion bridging of PEA by Ca2+ ions, in agreement with results available in literature on other similar polycarboxylates. An increase in salt valency reduces the value of critical C s for the onset of stabilization of the overall size and shape of the polymer chain. The critical C s ratio for the divalent to monovalent salt case is in excellent agreement with results of Langevin dynamics studies on model systems available in the literature. PEA-water H-bond half-life increases with C s for CaCl2, but no appreciable effect is seen for NaCl. The hydration of PEA becomes stronger in the presence of divalent salt. The strength of H-bond interaction energy is greater for cations as compared to anions of the salt. The salt cation effect in displacing water molecules from the vicinity of PEA, with increase in C s, is greater for NaCl solution. The decrease in water coordination to PEA carboxylate groups, due to increased C s, is more pronounced in NaCl solution. The nature of the behavior of the solvation enthalpy of PEA and the type of intermolecular interactions contributing to it, is in agreement with experimental observations from the literature. The hydration enthalpy of PEA in divalent CaCl2 aqueous salt solution is more exothermic compared to monovalent NaCl salt solution, in agreement with experimental data. The solvation of PEA is thermodynamically more favorable in the case of CaCl2 solution. The exothermic solvation enthalpy, H

  4. Electronic structure of γ-FeSi 2: angle resolved valence band photoemission and Si 2p photoemission

    Science.gov (United States)

    O'Brien, W. L.; Tonner, B. P.

    1994-06-01

    We have investigated the electronic properties of γ-FeSi 2 thin films using angle resolved valence band photoemission and Si2p core level photoemission. We find two features in the valence band data which are not present in the calculated density of states (DOS). One of these has a constant final state energy and we identify it as being due to a final state effect. Another feature, found near —1.8 eV binding energy, is located in an energy gap of the bulk DOS and is identified as a surface state. We have measured the energy dispersion of this surface state and of two bulk-like states. The surface state has a total energy shift of 0.4 eV and exhibits band extrema near positions of the (2×2) reconstructed surface Brillouin zone boundaries. High resolution Si 2p photoemission spectra on samples of varying thickness show that the Si 2p binding energy is higher in the suicide than in bulk silicon by 0.49 eV. We find no evidence of silicon adatoms in our Si 2p photoemission results.

  5. Insights into the Electronic Structure of Ozone and Sulfur Dioxide from Generalized Valence Bond Theory: Addition of Hydrogen Atoms.

    Science.gov (United States)

    Lindquist, Beth A; Takeshita, Tyler Y; Dunning, Thom H

    2016-05-05

    Ozone (O3) and sulfur dioxide (SO2) are valence isoelectronic species, yet their properties and reactivities differ dramatically. In particular, O3 is highly reactive, whereas SO2 is chemically relatively stable. In this paper, we investigate serial addition of hydrogen atoms to both the terminal atoms of O3 and SO2 and to the central atom of these species. It is well-known that the terminal atoms of O3 are much more amenable to bond formation than those of SO2. We show that the differences in the electronic structure of the π systems in the parent triatomic species account for the differences in the addition of hydrogen atoms to the terminal atoms of O3 and SO2. Further, we find that the π system in SO2, which is a recoupled pair bond dyad, facilitates the addition of hydrogen atoms to the sulfur atom, resulting in stable HSO2 and H2SO2 species.

  6. Valence band electronic structure and band alignment of LaAlO{sub 3}/SrTiO{sub 3}(111) heterointerfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gabel, J.; Scheiderer, P.; Zapf, M.; Schuetz, P.; Sing, M.; Claessen, R. [Physikalisches Institut and Roentgen Center for Complex Material Systems (RCCM), Universitaet Wuerzburg (Germany); Schlueter, C.; Lee, T.L. [Diamond Light Source, Didcot (United Kingdom)

    2015-07-01

    As in the famous LaAlO{sub 3}(LAO)/SrTiO{sub 3}(STO) (001) a two-dimensional electron system (2DES) also forms at the interface between LAO and STO in (111) orientation. A distinct feature of the (111) interface is its peculiar real space topology. Each bilayer represents a buckled honeycomb lattice similar to graphene which is known theoretically to host various topologically non-trivial states. Bilayer STO in proximity to the interface can be regarded as a three-orbital generalization of graphene with enhanced electron correlations making it a promising candidate for the realization of strongly correlated topological phases. We have investigated the electronic structure of the LAO/STO (111) heterostructure in relation to the oxygen vacancy concentration which we can control by synchrotron light irradiation and oxygen dosing. With hard X-ray photoemission we study the core levels, whereas resonant soft X-ray photoemission is used to probe the interfacial valence band (VB) states. Two VB features are found: a peak at the Fermi level associated with the 2DES and in-gap states at higher binding energies attributed to oxygen vacancies. By varying the oxygen vacancy contribution we can tune the emergence of the VB states and engineer the interfacial band alignment.

  7. Assessment of Electron Propagator Methods for the Simulation of Vibrationally Resolved Valence and Core Photoionization Spectra.

    Science.gov (United States)

    Baiardi, A; Paoloni, L; Barone, V; Zakrzewski, V G; Ortiz, J V

    2017-07-11

    The analysis of photoelectron spectra is usually facilitated by quantum mechanical simulations. Because of the recent improvement of experimental techniques, the resolution of experimental spectra is rapidly increasing, and the inclusion of vibrational effects is usually mandatory to obtain a reliable reproduction of the spectra. With the aim of defining a robust computational protocol, a general time-independent formulation to compute different kinds of vibrationally resolved electronic spectra has been generalized to also support photoelectron spectroscopy. The electronic structure data underlying the simulation are computed using different electron propagator approaches. In addition to the more standard approaches, a new and robust implementation of the second-order self-energy approximation of the electron propagator based on a transition operator reference (TOEP2) is presented. To validate our implementation, a series of molecules has been used as test cases. The result of the simulations shows that, for ultraviolet photoionization spectra, the more accurate nondiagonal approaches are needed to obtain a reliable reproduction of vertical ionization energies but that diagonal approaches are sufficient for energy gradients and pole strengths. For X-ray photoelectron spectroscopy, the TOEP2 approach, besides being more efficient, is also the most accurate in the reproduction of both vertical ionization energies and vibrationally resolved bandshapes.

  8. The electronic structure of the mixed valence compound Pb3O4

    NARCIS (Netherlands)

    Groot, R.A. de; Haas, C.; deGroot, R.A.

    Ab initio self-consistent calculations of the electronic structure of Pb3O4 are presented. The calculations show that Pb3O4 is a semiconductor. The calculated bandgap of 1.1 eV is smaller than the observed gap of 2.1-2.2 eV. The calculations show strong hybridization between Pb(6s) and O(2p) states.

  9. Interpretation of monoclinic hafnia valence electron energy-loss spectra by time-dependent density functional theory

    Science.gov (United States)

    Hung, L.; Guedj, C.; Bernier, N.; Blaise, P.; Olevano, V.; Sottile, F.

    2016-04-01

    We present the valence electron energy-loss spectrum and the dielectric function of monoclinic hafnia (m -HfO2) obtained from time-dependent density-functional theory (TDDFT) predictions and compared to energy-filtered spectroscopic imaging measurements in a high-resolution transmission-electron microscope. Fermi's golden rule density-functional theory (DFT) calculations can capture the qualitative features of the energy-loss spectrum, but we find that TDDFT, which accounts for local-field effects, provides nearly quantitative agreement with experiment. Using the DFT density of states and TDDFT dielectric functions, we characterize the excitations that result in the m -HfO2 energy-loss spectrum. The sole plasmon occurs between 13 and 16 eV, although the peaks ˜28 and above 40 eV are also due to collective excitations. We furthermore elaborate on the first-principles techniques used, their accuracy, and remaining discrepancies among spectra. More specifically, we assess the influence of Hf semicore electrons (5 p and 4 f ) on the energy-loss spectrum, and find that the inclusion of transitions from the 4 f band damps the energy-loss intensity in the region above 13 eV. We study the impact of many-body effects in a DFT framework using the adiabatic local-density approximation (ALDA) exchange-correlation kernel, as well as from a many-body perspective using "scissors operators" matched to an ab initio G W calculation to account for self-energy corrections. These results demonstrate some cancellation of errors between self-energy and excitonic effects, even for excitations from the Hf 4 f shell. We also simulate the dispersion with increasing momentum transfer for plasmon and collective excitation peaks.

  10. A study of the valence shell electronic states of s-triazine by photoabsorption spectroscopy and ab initio calculations

    DEFF Research Database (Denmark)

    Holland, D.M.P.; Shaw, D.A.; Stener, Mauro

    2016-01-01

    absorption bands due to excitation from the 1e00 or 6e0 orbitals. The interpretation of the experimental spectrum has been guided by transition energies and oscillator strengths, for Rydberg and valence states, calculated with the time-dependent version of density functional theory and with the coupled...... cluster linear response approach. The theoretical studies indicate that Rydberg/Rydberg and Rydberg/valence mixing is important....

  11. The role of TM’s (M’s d valence electrons in TM@X12 and M@X12 clusters

    Directory of Open Access Journals (Sweden)

    Zhiyun Tan

    2016-12-01

    Full Text Available Using the density functional theory method, the icosahedral TM@X12 (M@X12 clusters (TM=Mn, Tc, Re; M=Zn, Cd, Hg; and X=Sn, Ge, which are composed of Sn12 (Ge12 shell covering a single TM (M atom, have been systematically examined to explore the role of TM’s (M’s d valence electrons playing in the clusters. The results show that the magnetism originate from the contribution of TM’s d valence electrons to TM@X12 clusters, where TM’s (M’s d valence electrons are not included in the superatomic electronic states to TM@X12 (M@X12 clusters. Taking into account the structural stability (imaginary frequency, binding energy, embedding energy, and core-shell interaction as well as the chemical stability (HOMO-LUMO gap after, we proposed that TM@X12 and M@X12 clusters can be assigned as the protyle superatoms. Furthermore, the results suggest that M@C60 clusters can not be superatoms, because their negative embedding energies and the distance from the center atom (M to C atom is larger than the sum of their Van Waals radii. Interestingly enough, we may obtain a simple judging method: for a magnetic superatom, the smaller the energy gap between the highest occupied magnetic state (HOMS and Fermi level or HOMO (MOgap, or MFgap, the easier on the change of its spin magnetic moment.

  12. Fe valence determination and Li elemental distribution in lithiated FeO₀.₇F₁.₃/C nanocomposite battery materials by electron energy loss spectroscopy (EELS).

    Science.gov (United States)

    Cosandey, F; Su, D; Sina, M; Pereira, N; Amatucci, G G

    2012-01-01

    Electron energy loss spectroscopy (EELS) is a powerful technique for studying Li-ion battery materials because the valence state of the transition metal in the electrode and charge transfer during lithiation and delithiation processes can be analyzed by measuring the relative intensity of the transition metal L₃ and L₂ lines. In addition, the Li distribution in the electrode material can be mapped with nanometer scale resolution. Results obtained for FeO₀.₇F₁.₃/C nanocomposite positive electrodes are presented. The Fe average valence state as a function of lithiation (discharge) has been measured by EELS and results are compared with average Fe valence obtained from electrochemical data. For the FeO₀.₇F₁.₃/C electrode discharged to 1.5 V, phase decomposition is observed and valence mapping with sub-nanometer resolution was obtained by STEM/EELS analysis. For the lowest discharge voltage of 0.8 V, a surface electrolyte inter-phase (SEI) layer is observed and STEM/EELS results are compared with the Li-K edges obtained for various Li standard compounds (LiF, Li₂CO₃ and Li₂O). Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Probability of Two-Step Photoexcitation of Electron from Valence Band to Conduction Band through Doping Level in TiO2.

    Science.gov (United States)

    Nishikawa, Masami; Shiroishi, Wataru; Honghao, Hou; Suizu, Hiroshi; Nagai, Hideyuki; Saito, Nobuo

    2017-08-17

    For an Ir-doped TiO 2 (Ir:TiO 2 ) photocatalyst, we examined the most dominant electron-transfer path for the visible-light-driven photocatalytic performance. The Ir:TiO 2 photocatalyst showed a much higher photocatalytic activity under visible-light irradiation than nondoped TiO 2 after grafting with the cocatalyst of Fe 3+ . For the Ir:TiO 2 photocatalyst, the two-step photoexcitation of an electron from the valence band to the conduction band through the Ir doping level occurred upon visible-light irradiation, as observed by electron spin resonance spectroscopy. The two-step photoexcitation through the doping level was found to be a more stable process with a lower recombination rate of hole-electron pairs than the two-step photoexcitation process through an oxygen vacancy. Once electrons are photoexcited to the conduction band by the two-step excitation, the electrons can easily transfer to the surface because the conduction band is a continuous electron path, whereas the electrons photoexcited at only the doping level could not easily transfer to the surface because of the discontinuity of this path. The observed two-step photoexcitation from the valence band to the conduction band through the doping level significantly contributes to the enhancement of the photocatalytic performance.

  14. Charge-shift bonding--a class of electron-pair bonds that emerges from valence bond theory and is supported by the electron localization function approach.

    Science.gov (United States)

    Shaik, Sason; Danovich, David; Silvi, Bernard; Lauvergnat, David L; Hiberty, Philippe C

    2005-10-21

    This paper deals with a central paradigm of chemistry, the electron-pair bond. Valence bond (VB) theory and electron-localization function (ELF) calculations of 21 single bonds demonstrate that along the two classical bond families of covalent and ionic bonds, there exists a class of charge-shift bonds (CS bonds) in which the fluctuation of the electron pair density plays a dominant role. In VB theory, CS bonding manifests by way of a large covalent-ionic resonance energy, RE(CS), and in ELF by a depleted basin population with large variances (fluctuations). CS bonding is shown to be a fundamental mechanism that is necessary to satisfy the equilibrium condition, namely the virial ratio of the kinetic and potential energy contributions to the bond energy. The paper defines the atomic propensity and territory for CS bonding: Atoms (fragments) that are prone to CS bonding are compact electronegative and/or lone-pair-rich species. As such, the territory of CS bonding transcends considerations of static charge distribution, and involves: a) homopolar bonds of heteroatoms with zero static ionicity, b) heteropolar sigma and pi bonds of the electronegative and/or electron-pair-rich elements among themselves and to other atoms (e.g., the higher metalloids, Si, Ge, Sn, etc), c) all hypercoordinate molecules. Several experimental manifestations of charge-shift bonding are discussed, such as depleted bonding density, the rarity of ionic chemistry of silicon in condensed phases, and the high barriers of halogen-transfer reactions as compared to hydrogen-transfers.

  15. Hierarchy effect on electronic structure and core-to-valence transitions in bone tissue: perspectives in medical nanodiagnostics of mineralized bone

    Science.gov (United States)

    Samoilenko, Dmitrii O.; Avrunin, Alexander S.; Pavlychev, Andrey A.

    2017-06-01

    Electronic structure and core-to-valence transitions in bone tissue are examined in the framework of the morphological 3DSL model that takes into account (i) structural and functional organization of the skeleton in the normal and pathological conditions and (ii) peculiarities of electron wave propagation in a three-dimensional superlattice of "black-nanocrystallites-in-muddy-waters". Our focus is on the HAP-to-bone red shifts of core-to-valence transitions near Ca and P 2p and O 1s edges in single-crystal hydroxyapatite (HAP) Ca10(PO4)6(OH)2. The origin of the HAP-to-bone shift is discussed and the extended comparative analysis of the experimental data is performed. The detected spectral shift is assigned with the effect of hierarchical organization of bone tissue. This hierarchy effect on the core-to-valence transition energies is regarded as a promising tool for medical imaging and perspective pathway for nanodiagnostics of mineralized bone. Contribution to the Topical Issue "Dynamics of Systems at the Nanoscale", edited by Andrey Solov'yov and Andrei Korol.

  16. All-electron exact exchange treatment of semiconductors: effect of core-valence interaction on band-gap and d-band position.

    Science.gov (United States)

    Sharma, S; Dewhurst, J K; Ambrosch-Draxl, C

    2005-09-23

    We present the first all-electron full-potential exact exchange (EXX) Kohn-Sham density functional calculations on a range of semiconductors and insulators (Ge, GaAs, CdS, Si, ZnS, C, BN, Ne, Ar, Kr, and Xe). We remove one of the main computational obstacles of such calculations by the use of a highly efficient basis for inversion of the response function. We find that the band gaps are not as close to experiment as those obtained from previous pseudopotential EXX calculations. The locations of d bands, determined using the full-potential EXX method, are in excellent agreement with experiment, irrespective of whether these are core, semicore, or valence states. We conclude that the inclusion of the core-valence interaction is necessary for accurate determination of EXX Kohn-Sham band structures and that EXX alone is not a complete answer to the band-gap problem in semiconductors.

  17. Single-Nanoparticle Resolved Biomimetic Long-Range Electron Transfer and Electrocatalysis of Mixed-Valence Nanoparticles

    DEFF Research Database (Denmark)

    Zhu, Nan; Hao, Xian; Ulstrup, Jens

    2016-01-01

    stability in vitro. Development of robust biomimetic nanostructures is therefore highly desirable. Here, with Prussian blue nanoparticles (PBNPs) as an example we have demonstrated the preparation of highly stable and water-soluble mixed-valence nanoparticles under mild conditions. We have mapped...

  18. Electric Field Generation and Control of Bipartite Quantum Entanglement between Electronic Spins in Mixed Valence Polyoxovanadate [GeV14O40](8).

    Science.gov (United States)

    Palii, Andrew; Aldoshin, Sergey; Tsukerblat, Boris; Borràs-Almenar, Juan José; Clemente-Juan, Juan Modesto; Cardona-Serra, Salvador; Coronado, Eugenio

    2017-08-21

    As part of the search for systems in which control of quantum entanglement can be achieved, here we consider the paramagnetic mixed valence polyoxometalate K2Na6[GeV14O40]·10H2O in which two electrons are delocalized over the 14 vanadium ions. Applying a homogeneous electric field can induce an antiferromagnetic coupling between the two delocalized electronic spins that behave independently in the absence of the field. On the basis of the proposed theoretical model, we show that the external field can be used to generate controllable quantum entanglement between the two electronic spins traveling over a vanadium network of mixed valence polyoxoanion [GeV14O40](8-). Within a simplified two-level picture of the energy pattern of the electronic pair based on the previous ab initio analysis, we evaluate the temperature and field dependencies of concurrence and thus indicate that the entanglement can be controlled via the temperature, magnitude, and orientation of the electric field with respect to molecular axes of [GeV14O40](8-).

  19. Atomic valence in molecular systems

    Science.gov (United States)

    Bochicchio, R. C.; Lain, L.; Torre, A.

    2003-06-01

    Atomic valence in molecular systems is described as a partitioning of the hole distribution, the complementary part of the particle distribution. In this scheme, valence splits into three contributions, related to electron spin density, nonuniform occupancy of orbitals (nonpairing terms) and exchange density (pairing terms), respectively, and whose importance depends on the nature of the state of the system. Calculations carried out for correlated CI and Hartree-Fock state functions in both Mulliken and topological AIM type partitionings as well as theoretical results show the suitability of this formulation for describing valence concepts.

  20. The unusual electronic mechanism of the [1,5] hydrogen shift in (Z)-1,3-pentadiene predicted by modern valence bond theory.

    Science.gov (United States)

    Karadakov, Peter B; Hill, J Grant; Cooper, David L

    2007-01-01

    The combination of modern valence bond theory in its spin-coupled (SC) form [SC(6)/6-31G*] and an intrinsic reaction coordinate calculation (MP2/6-31G* IRC) is used in order to obtain a model for the electronic mechanism of the gas-phase [1s,5s] hydrogen shift in (Z)-1,3-pentadiene. It is shown that this reaction follows an unusual heterolytic mechanism consistent with the C(s) symmetry of the transition state and involving the simultaneous movements of three well-defined orbital pairs. One of these is responsible for the sigma bond which initially attaches the migrating hydrogen to carbon 5 and, later on, to carbon 1. The second one realises the pi bond between carbons 3 and 4 which during the course of the reaction moves over carbons 2 and 3, while the third pair, initially involved in the pi bond between carbons 1 and 2 has no other choice but to embark on a long-range journey across the ring, ending up over carbons 4 and 5. While at first sight, it might appear that an electronic mechanism of this type would preclude the existence of an aromatic transition state, we have been able to show that the electronic structure of the transition state for this sigmatropic hydrogen shift has much in common with a hitherto apparently unknown alternative modern valence bond description of benzene involving 'antipairs' and so it can be considered to be aromatic.

  1. Interplay of magnetism and valence instabilities in lanthanide systems

    Directory of Open Access Journals (Sweden)

    José Luiz Ferreira

    2016-06-01

    Full Text Available The valence instability in lanthanide systems is described within an extended periodic Anderson Hamiltonian (EPAM which includes Coulomb repulsion between f- and conduction- electrons, allowing to describe both discontinuous and continuous valence variations. We investigate the connection between valence and magnetism in this model and show that it can be applied to several lanthanide compounds showing both magnetic and valence instabilities.

  2. The valence of small fullerenes

    Science.gov (United States)

    Milani, C.; Giambelli, C.; Roman, H. E.; Alasia, F.; Benedek, G.; Broglia, R. A.; Sanguinetti, S.; Yabana, K.

    1996-08-01

    The production and isolation of small fullerenes and of their stable compounds and the knowledge of their chemistry should pave the way to the syntesis of novel carbon-based cluster-assembled materials like carbon clathrates, hollow diamonds and diamond-like thin films. In this quest, the knowledge of the valence of the small fullerenes is essential. We report here that the small fullerenes C n (20 ≤ n ≤ 32), aside from the well known values associated with the local one electron picture of dangling bonds, display hidden valences connected with the free electron picture of the shell structure of π-electrons.

  3. Relativistic configuration-interaction calculations for atoms with one valence electron based on altering hydrogenlike or Dirac-Fock spin orbitals

    Science.gov (United States)

    Głowacki, Leszek

    2015-12-01

    Relativistic configuration-interaction calculations using hydrogenlike or Dirac-Fock spin orbitals of the transition from the ground state to some n p1 /2 , n p3 /2 low-lying excited states for the alkali metals are presented. In these calculations each virtual spin orbital corresponds to a unique noninteger atomic number determined iteratively using the virtual-particle model. The virtual-particle model based on "condensed-space" idea is here adopted to many electron systems consisting of a single valence electron and the core. The transition energy and the oscillator strength values were computed for sodium, potassium, rubidium, cesium, and francium. Both hydrogenlike and Dirac-Fock basis functions have been used in the computations for comparison.

  4. Levels of valence

    Directory of Open Access Journals (Sweden)

    Vera eShuman

    2013-05-01

    Full Text Available The distinction between the positive and the negative is fundamental in our emotional life. In appraisal theories, in particular in the component process model of emotion (Scherer, 1984, 2010, qualitatively different types of valence are proposed based on appraisals of (unpleasantness, goal obstructiveness/conduciveness, low or high power, self- (incongruence, and moral badness/goodness. This multifaceted conceptualization of valence is highly compatible with the frequent observation of mixed feelings in real life. However, it seems to contradict the one-dimensional conceptualization of valence often encountered in psychological theories, and the notion of valence as a common currency used to explain choice behavior. Here, we propose a framework to integrate the seemingly disparate conceptualizations of multifaceted valence and one-dimensional valence by suggesting that valence should be conceived at different levels, micro and macro. Micro-valences correspond to qualitatively different types of evaluations, potentially resulting in mixed feelings, whereas one-dimensional macro-valence corresponds to an integrative common currency to compare alternatives for choices. We propose that conceptualizing levels of valence may focus research attention on the mechanisms that relate valence at one level (micro to valence at another level (macro, leading to new hypotheses and addressing various concerns that have been raised about the valence concept, such as the valence-emotion relation.

  5. Application of Concentrated Electron Beams in Extra-Vacuum Technologies

    Science.gov (United States)

    Gorshkov, Oleg; Iliin, A. A.; Lovtsov, A. S.; Rizakhanov, R. N.

    2001-10-01

    At present time the rise in development of the technology with using the concentrated electron beams in gas with atmospheric pressure is observed. Besides the technologies, which are usually carried out in vacuum and connected with surface modification by the concentrated energy flows (welding, cutting, metal surface hardening), at present time the plasma chemical processes become of greater interest. These are processes with using the beam of fast electrons to initiate the plasma chemical reactions. One of such technologies is gas cleaning of the toxic impurities (nitrogen oxides and sulfur oxides and etc.) The electron-beam gas cleaning of the toxic impurities (for example Ebara-process) is based on radiation-enhanced combining of toxic impurities. The disadvantage of this method are high level of consumed power during the gas cleaning and difficulties in devices development for the output of electron beam with megawatt unit power with foil outlet, as the facilities of this very power are necessary for the real industrial application. These problems can be solved by using the devices with concentrated electron beam output into the atmosphere. In this case the beam is transported into the dense gas through the system of lock chambers, independently pumped. But unlike the beam, output through the foil window, the concentrated electron beam is characterized by the noticeable spatial irregularity in distribution of temperature, plasma concentration and area of radiation. This paper is devoted to consideration of using the concentrated electron beams in extra-vacuum technologies.

  6. Influence of chromium concentration on the electron magnetic resonance linewidth of Cr3+ in SrTiO3

    Directory of Open Access Journals (Sweden)

    Ronaldo Sergio de Biasi

    2012-06-01

    Full Text Available Electron magnetic resonance (EMR spectra of Cr3+ ions in samples of chromium-doped strontium titanate (SrTiO3 have been studied at room temperature for chromium concentrations between 0.20 and 1.00 mol%. According to previous studies, chromium substitutes Ti4+ sites in the lattice and its preferred valence state is Cr4+, which is EMR silent in the X-band, but the trivalent state can be produced by illumination or codoping with Nb. In the present work, the codoping method was used; the results show the electron magnetic resonance linewidth of the Cr3+ spectrum increases with increasing chromium concentration and that the range of the exchange interaction between Cr3+ ions is about 0.96 nm.

  7. Metal-to-metal electron transfer and magnetic interactions in a mixed-valence Prussian Blue analogue

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, A. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany)]. E-mail: ashis62@rediffmail.com; Saha, S. [Department of Chemistry, Jadavpur University, Kolkata 700032 (India); Koner, S. [Department of Chemistry, Jadavpur University, Kolkata 700032 (India); Ksenofontov, V. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Reiman, S. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Guetlich, P. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany)]. E-mail: guetlich@uni-mainz.de

    2006-07-15

    In search of a new Prussian Blue analogue exhibiting fascinating magnetic properties, potassium manganese hexacyanoferrate, K{sub 0.2}Mn{sub 0.66}{sup II}Mn{sub 1.44}{sup III}[Fe{sub 0.2}{sup II}Fe{sub 0.8}{sup III}(CN){sub 6}]O{sub 0.6}= {sub 6}(CH{sub 3}COO){sub 1.32}], 7.6H{sub 2}O, has been synthesized. This compound undergoes a paramagnetic to ferrimagnetic transition at 10K. Temperature and magnetic field-dependent magnetization studies of this compound have revealed different spin alignments below and above 3K. The nature of possible magnetic interactions between the nearest neighbor magnetic centers has been discussed in order to explore the origin of the observed magnetic interactions. Moessbauer spectroscopic study at different temperatures demonstrates the presence of both Fe{sup III} and Fe{sup II} in low-spin states in this compound. Quantitative analysis of the Fe{sup III} and Fe{sup II} ions, and their temperature dependence exhibits the existence of an electron transfer phenomenon between Mn and Fe ions [Fe{sup III} (t{sub 2g}{sup 5}, S=1/2)-CN-Mn{sup II} (t{sub 2g}{sup 3}e{sub g}{sup 2}, S=5/2)]-bar [Fe{sup II} (t{sub 2g}{sup 6}, S=0)-CN-Mn{sup III} (t{sub 2g}{sup 3}e{sub g}{sup 1}, S=2)]. This electron transfer has been remarkably enhanced in the magnetically ordered region.

  8. Valence shell charge concentrations at pentacoordinate d0 transition-metal centers: non-VSEPR structures of Me2NbCl3 and Me3NbCl2.

    Science.gov (United States)

    McGrady, G Sean; Haaland, Arne; Verne, Hans Peter; Volden, Hans Vidar; Downs, Anthony J; Shorokhov, Dmitry; Eickerling, Georg; Scherer, Wolfgang

    2005-08-19

    The molecular structures of the monomeric, pentacoordinated methylchloroniobium(IV) compounds Me3NbCl2 and Me2NbCl3 have been determined by gas electron diffraction (GED) and density functional theory (DFT) calculations, and, for Me3NbCl2, by single crystal X-ray diffraction. Each of the molecules is found to have a heavy-atom skeleton in the form of a trigonal bipyramid (TBP) with Cl atoms in the axial positions, in accord with their vibrational spectra. The TBP is somewhat distorted in the case of Me2NbCl3 with the two axial Nb--Cl bonds bent away from the equatorial, slightly shorter Nb--Cl bond. In the case of Me3NbCl2, moreover, the X-ray model suggests structural distortions away from the idealized C3h geometry, in line with the results of quantum chemical calculations. Structure optimizations by DFT calculations and least-squares refinement to the GED data yield the following structural parameters (calcd/exptl; eq=equatorial; ax=axial; distances in A, angles in degrees; average values in brackets): Me3NbCl2, in C(3v) symmetry, Nb--Cl 2.370/2.319(3), Nb--C 2.173/2.152(4), C--H 1.096/1.124(5), angle-spherical NbCH 109.3/105.2(8), angle-spherical ClNbC 92.2/93.3(2), angle-spherical CNbC 119.9/119.7(1); Me2NbCl3, in C(2v) symmetry, Nb--Cl(ax) 2.361/2.304(5), Nb--Cl(eq) 2.321/2.288(9), Nb--C 2.180/2.135(9), C--H 1.094/1.12(1), angle-spherical Cl(ax)NbCl(eq) 98.5/96.5(6), angle-spherical CNbC 121.0/114(2), angle-spherical NbCH 108.9/109(2). The electronic structures of Me2NbCl3 and Me3NbC(2 have been explored by rigorous analysis of both the wavefunction and the topology of the electron density, employing DFT calculations. Hence the structures of these compounds are shown to reflect repulsion between the Nb--C and Nb--Cl bonding electron density and charge concentrations induced by the methyl ligands in the valence shell of the Nb atom and arising mainly from use of Nb(4d) functions in the Nb--C bonds.

  9. An electronic nose for quantitative determination of gas concentrations

    Science.gov (United States)

    Jasinski, Grzegorz; Kalinowski, Paweł; Woźniak, Łukasz

    2016-11-01

    The practical application of human nose for fragrance recognition is severely limited by the fact that our sense of smell is subjective and gets tired easily. Consequently, there is considerable need for an instrument that can be a substitution of the human sense of smell. Electronic nose devices from the mid 1980s are used in growing number of applications. They comprise an array of several electrochemical gas sensors with partial specificity and a pattern recognition algorithms. Most of such systems, however, is only used for qualitative measurements. In this article usage of such system in quantitative determination of gas concentration is demonstrated. Electronic nose consist of a sensor array with eight commercially available Taguchi type gas sensor. Performance of three different pattern recognition algorithms is compared, namely artificial neural network, partial least squares regression and support vector machine regression. The electronic nose is used for ammonia and nitrogen dioxide concentration determination.

  10. Ab initio valence calculations in chemistry

    CERN Document Server

    Cook, D B

    1974-01-01

    Ab Initio Valence Calculations in Chemistry describes the theory and practice of ab initio valence calculations in chemistry and applies the ideas to a specific example, linear BeH2. Topics covered include the Schrödinger equation and the orbital approximation to atomic orbitals; molecular orbital and valence bond methods; practical molecular wave functions; and molecular integrals. Open shell systems, molecular symmetry, and localized descriptions of electronic structure are also discussed. This book is comprised of 13 chapters and begins by introducing the reader to the use of the Schrödinge

  11. Valence electron distribution in La2 Li½ Cu½ O4, Nd2 Li½ Ni½ O4, and La2 Li½ Co½ O4

    NARCIS (Netherlands)

    Hu, Z.; Mazumdar, Chandan; Kaindl, G.; Groot, F.M.F. de; Warda, S.A.; Reinen, D.

    1998-01-01

    The distribution of valence electrons between transition metals (TM) and oxygen has been studied via X-ray absorption near-edge fine structure (XANES) at the TM-L2,3 and O-K thresholds for La2 Li½ Cu½ O4 , Nd2 Li½ Ni½ O4 , and La2 Li½ Co½ O4 . Simulations of the TM-L2,3 XANES

  12. Density functional investigations of the properties and thermochemistry of UF6 and UF5 using valence-electron and all-electron approaches.

    Science.gov (United States)

    Batista, Enrique R; Martin, Richard L; Hay, P Jeffrey; Peralta, Juan E; Scuseria, Gustavo E

    2004-08-01

    The structural properties and thermochemistry of UF6 and UF5 have been investigated using both Hartree-Fock and density functional theory (DFT) approximations. Within the latter approach, the local spin-density approximation, the generalized gradient approximation, and hybrid density functionals were considered. To describe the uranium atom we employed small-core (60 electrons) and large-core (78 electrons) relativistic effective core potentials (RECPs), as well as the all-electron approximation based on the two-component third-order Douglas-Kroll-Hess Hamiltonian. For structural properties, we obtained very good agreement with experiment with DFT and both large and small-core RECPs. The best match with experiment is given by the hybrid functionals with the small-core RECP. The bond dissociation energy (BDE) was obtained from the relative energies of the fragments [UF6 --> UF5 + F], corrected for zero-point energy and spin-orbit interaction. Very good agreement was found between the BDE obtained from all-electron calculations and those calculated with the small-core RECP, while those from the large-core RECP are off by more than 50%. In order to obtain good agreement with experiment in the BDE it is imperative to work with hybrid density functionals and a small-core RECP. (c) 2004 American Institute of Physics.

  13. Concept of effective states of atoms in compounds to describe properties determined by the densities of valence electrons in atomic cores

    OpenAIRE

    Titov, Anatoly V.; Lomachuk, Yuriy V.; Skripnikov, Leonid V.

    2014-01-01

    A new approach for describing the effective electronic states of "atoms in compounds" to study the properties of molecules and condensed matter which are circumscribed by the operators heavily concentrated in atomic cores is proposed. Among the properties are hyperfine structure, space parity (P) and time reversal invariance (T) nonconservation effects, chemical shifts of x-ray emission lines (XES), M\\"{o}ssbauer effect, etc. Advantage of the approach is that a good quantitative agreement of ...

  14. Concentration of precious metals during their recovery from electronic waste.

    Science.gov (United States)

    Cayumil, R; Khanna, R; Rajarao, R; Mukherjee, P S; Sahajwalla, V

    2016-11-01

    The rapid growth of electronic devices, their subsequent obsolescence and disposal has resulted in electronic waste (e-waste) being one of the fastest increasing waste streams worldwide. The main component of e-waste is printed circuit boards (PCBs), which contain substantial quantities of precious metals in concentrations significantly higher than those typically found in corresponding ores. The high value and limited reserves of minerals containing these metals makes urban mining of precious metals very attractive. This article is focused on the concentration and recovery of precious metals during pyro-metallurgical recycling of waste PCBs. High temperature pyrolysis was carried out for ten minutes in a horizontal tube furnace in the temperature range 800-1350°C under Argon gas flowing at 1L/min. These temperatures were chosen to lie below and above the melting point (1084.87°C) of copper, the main metal in PCBs, to study the influence of its physical state on the recovery of precious metals. The heat treatment of waste PCBs resulted in two different types of solid products, namely a carbonaceous non-metallic fraction (NMFs) and metallic products, composed of copper rich foils and/or droplets and tin-lead rich droplets and some wires. Significant proportions of Ag, Au, Pd and Pt were found concentrated within two types of metallic phases, with very limited quantities retained by the NMFs. This process was successful in concentrating several precious metals such as Ag, Au, Pd and Pt in a small volume fraction, and reduced volumes for further processing/refinement by up to 75%. The amounts of secondary wastes produced were also minimised to a great extent. The generation of precious metals rich metallic phases demonstrates high temperature pyrolysis as a viable approach towards the recovery of precious metals from e-waste. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. The Physics of the Hume-Rothery Electron Concentration Rule

    Directory of Open Access Journals (Sweden)

    Uichiro Mizutani

    2017-01-01

    Full Text Available For a long time we have shared the belief that the physics of the Hume-Rothery electron concentration rule can be deepened only through thorough investigation of the interference phenomenon of itinerant electrons with a particular set of lattice planes, regardless of whether d-states are involved near the Fermi level or not. For this purpose, we have developed the FLAPW-Fourier theory (Full potential Linearized Augmented Plane Wave, which is capable of determining the square of the Fermi diameter, ( 2 k F 2 , and the number of itinerant electrons per atom, e/a, as well as the set of lattice planes participating in the interference phenomenon. By determining these key parameters, we could test the interference condition and clarify how it contributes to the formation of a pseudogap at the Fermi level. Further significant progress has been made to allow us to equally handle transition metal (TM elements and their compounds. A method of taking the center of gravity energy for energy distribution of electrons with a given electronic state has enabled us to eliminate the d-band anomaly and to determine effective ( 2 k F 2 , and e/a, even for systems involving the d-band or an energy gap across the Fermi level. The e/a values for 54 elements covering from Group 1 up to Group 16 in the Periodic Table, including 3d-, 4d- and 5d-elements, were determined in a self-consistent manner. The FLAPW-Fourier theory faces its limit only for elements in Group 17 like insulating solids Cl and their compounds, although the value of e/a can be determined without difficulty when Br becomes metallic under high pressures. The origin of a pseudogap at the Fermi level for a large number of compounds has been successfully interpreted in terms of the interference condition, regardless of the bond-types involved in the van Arkel-Ketelaar triangle map.

  16. Simulating Ru L 3 -Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  17. Dynamics of electron impact ionization of the outer and inner valence (1t{sub 2} and 2a{sub 1}) molecular orbitals of CH{sub 4} at intermediate and large ion recoil momentum

    Energy Technology Data Exchange (ETDEWEB)

    Lahmam-Bennani, A; Naja, A; Staicu Casagrande, E M; Okumus, N [Laboratoire des Collisions Atomiques et Moleculaires (LCAM), Universite Paris-Sud 11, Bat. 351, 91405 Orsay Cedex (France); Dal Cappello, C [Laboratoire de Physique Moleculaire et des Collisions, Institut de Physique, ICPMB (FR 2843), Universite Paul Verlaine-Metz, 1 rue Arago, 57078 Metz Cedex 3 (France); Charpentier, I [Laboratoire de Physique et Mecanique des Materiaux (UMR 7554), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz Cedex 1 (France); Houamer, S [Laboratoire de Physique Quantique et Systemes Dynamiques, Universite Ferhat Abbas, Setif (Algeria)

    2009-08-28

    The triply differential cross section has been measured for electron-impact ionization of the outer valence 1t{sub 2} and the inner valence 2a{sub 1} orbitals of methane using the (e,2e) technique with coplanar asymmetric kinematics. The measurements are performed at scattered electron energy of 500 eV, ejected electron energy of 12, 37 and 74 eV and for scattering angle of the fast outgoing electron of 6 deg. This kinematics is characterized by a target ion recoil momentum ranging from moderate (0.25 au) to very large (3.2 au) values. The results are compared with theoretical cross sections calculated using the 1CW and the BBK models recently extended to molecules. The experimental cross sections exhibit a very large recoil scattering, especially for the inner 2a{sub 1} molecular orbital, which is not predicted by the theory. The differences between experiment and theory are attributed to the very strong scattering from the ion, not properly accounted for by theory. This indicates the need for further theoretical developments as well as experimental investigations in order to correctly model the process of molecular ionization.

  18. THE VALENCE OF CORPUSCULAR PROTEINS.

    Science.gov (United States)

    Gorin, M H; Mover, L S

    1942-07-20

    BY THE USE OF TWO EXTREME MODELS: a hydrated sphere and an unhydrated rod the valence (net charge) of corpuscular proteins can be successfully calculated from electric mobility data by the Debye-Hückel theory (modified to include the effect of the ions in the ion atmosphere) in conjunction with the electrophoretic theory of Henry. As pointed out by Abramson, this permits a comparison with values for the valence from titration data. Electrometric titration measurements of serum albumin B (Kekwick) have been determined at several ionic strengths. These results, together with the available data in the literature for serum albumin B, egg albumin, and beta-lactoglobulin have been used to compare values for the valence calculated from measurements of titration, electrophoresis, and membrane potentials. The results indicate that the usual interpretation of titration curves is open to serious question. By extrapolation of the titration data to zero ionic strength and protein concentration, there results an "intrinsic" net charge curve describing the binding of H(+) (OH(-)) ion alone. This curve agrees closely, in each case, with values of the valence calculated from mobility data (which in turn are in close accord with those estimated from membrane potential measurements). The experimental titration curves in the presence of appreciable quantities of ions and protein deviate widely from the ideal curve. It is suggested that, under these conditions, binding of undissociated acid (base) leads to erroneous values for the net charge. This binding would not affect the electrophoretic mobility. Values of the net charge obtained by the two extreme models from electrophoretic data are in agreement within 15 to 20 per cent. The agreement between the cylindrical model and the titration data is somewhat better in each case than with the sphere; i.e., this comparison enables a choice to be made between asymmetry and hydration in the interpretation of results from sedimentation and

  19. Orbital Configuration of the Valence Electrons, Ligand Field Symmetry, and Manganese Oxidation States of the Photosynthetic Water Oxidizing Complex: Analysis of the S(2) State Multiline EPR Signals.

    Science.gov (United States)

    Zheng, Ming; Dismukes, G. Charles

    1996-05-22

    state is caused by change in the intermanganese exchange coupling, without appreciable change in the intrinsic hyperfine tensors. The lack of good simulations of the Ca(2+)-depleted MLS suggests that Ca(2+)-depletion changes both Mn ligation and intermanganese exchange coupling. The 3Mn(IV)-1Mn(III) oxidation model is disfavored because only approximate simulations could be found for the native MLS and no agreement with the NH(3)-bound MLS was obtained. The scalar part of the hyperfine tensors for both Mn(III) and Mn(IV) ions were found to approximate (+/-5%) the values for the dimanganese(III,IV) catalase enzyme, suggesting similar overall ligand types. However, the large (30%) anisotropic part of the Mn(III) hyperfine interaction is opposite in sign to that found in all tetragonally extended six-coordinate Mn(III) ions (i.e., the usual Jahn-Teller splitting). The distribution of spin density from the high-spin d(4) electron configuration of each Mn(III) ion corresponds to a flattened (oblate) ellipsoid. This electronic distribution is favored in five-coordinate ligand fields having trigonally compressed bipyramidal geometry, but it could also arise, in principle, in strained six-coordinate ligand fields having tetragonally compressed geometry, i.e. [Mn(2)(&mgr;-O)](4+) (reverse Jahn-Teller distortion). The resulting valence electronic configurations are described as e'(2)e"(2) and (d(pi))(3)(d(x)()()2(-)(y)()()2)(1), respectively, in contrast to the (d(pi))(3)(d(z)()()2)(1) configuration common to unstrained six-coordinate tetragonally-extended Mn(III) ions, such as found in the [Mn(2)(&mgr;-O)(2)](3+) core in several synthetic dimers and catalase. Both of the former geometries predict strongly oxidizing Mn(III) ions, thereby suggesting a structural basis for the oxidative reactivity of the Mn(4) cluster in the WOC. The magnetic model needed to explain the MLS is not readily reconciled with the simplest structural and electronic models deduced from EXAFS studies of

  20. Valency and molecular structure

    CERN Document Server

    Cartmell, E

    1977-01-01

    Valency and Molecular Structure, Fourth Edition provides a comprehensive historical background and experimental foundations of theories and methods relating to valency and molecular structures. In this edition, the chapter on Bohr theory has been removed while some sections, such as structures of crystalline solids, have been expanded. Details of structures have also been revised and extended using the best available values for bond lengths and bond angles. Recent developments are mostly noted in the chapter on complex compounds, while a new chapter has been added to serve as an introduction t

  1. Intervalence charge transfer transition in mixed valence complexes ...

    Indian Academy of Sciences (India)

    Permanent link: http://www.ias.ac.in/article/fulltext/jcsc/114/04/0431-0442. Keywords. Mixed valence complexes; intervalence charge transfer; rotaxane; inclusion complex; optical electron transfer; cyclodextrin. Abstract. Intervalence charge transfer properties were studied for a set of mixed valence complexes incorporating ...

  2. SparseMaps--A systematic infrastructure for reduced-scaling electronic structure methods. III. Linear-scaling multireference domain-based pair natural orbital N-electron valence perturbation theory.

    Science.gov (United States)

    Guo, Yang; Sivalingam, Kantharuban; Valeev, Edward F; Neese, Frank

    2016-03-07

    Multi-reference (MR) electronic structure methods, such as MR configuration interaction or MR perturbation theory, can provide reliable energies and properties for many molecular phenomena like bond breaking, excited states, transition states or magnetic properties of transition metal complexes and clusters. However, owing to their inherent complexity, most MR methods are still too computationally expensive for large systems. Therefore the development of more computationally attractive MR approaches is necessary to enable routine application for large-scale chemical systems. Among the state-of-the-art MR methods, second-order N-electron valence state perturbation theory (NEVPT2) is an efficient, size-consistent, and intruder-state-free method. However, there are still two important bottlenecks in practical applications of NEVPT2 to large systems: (a) the high computational cost of NEVPT2 for large molecules, even with moderate active spaces and (b) the prohibitive cost for treating large active spaces. In this work, we address problem (a) by developing a linear scaling "partially contracted" NEVPT2 method. This development uses the idea of domain-based local pair natural orbitals (DLPNOs) to form a highly efficient algorithm. As shown previously in the framework of single-reference methods, the DLPNO concept leads to an enormous reduction in computational effort while at the same time providing high accuracy (approaching 99.9% of the correlation energy), robustness, and black-box character. In the DLPNO approach, the virtual space is spanned by pair natural orbitals that are expanded in terms of projected atomic orbitals in large orbital domains, while the inactive space is spanned by localized orbitals. The active orbitals are left untouched. Our implementation features a highly efficient "electron pair prescreening" that skips the negligible inactive pairs. The surviving pairs are treated using the partially contracted NEVPT2 formalism. A detailed comparison

  3. C-H⋯Cl relevant discrepancy on structure, magnetic and electronic conductivity of two mixed-valence Cu ICu II coordination polymers

    Science.gov (United States)

    Shi, Ling; Yang, Ping; Huang, Guang; Li, Qian; Wang, Ning; Wu, Jian-Zhong; Yu, Ying

    2011-07-01

    Two mixed-valence Cu ICu II coordination polymers [Cu ICu II(qdiol)ClL] n (qdiol 2-=2,3-dioxyquinoxalinate, L=2,2'-bipyridine, 1; L=1,10-phenanthroline, 2) were obtained in basic ethanolic solution of CuCl 2, 1,4-dihydro-2,3-quinoxalinedione and L under the solvothermal condition. 1 and 2 are similar in composition, but differ remarkably in structure. The coordination modes of Cu II, qdiol 2- and L are identical in both complexes. But the Cu I ions are two- and three-coordinated, and the Cl - ions are terminal and bridging, in 1 and 2, respectively, which are relevant to the significantly different C-H⋯Cl hydrogen bonding pattern of bpy and phen. The temperature variable magnetic susceptibilities show that 1 is paramagnetic and 2 is weakly antiferromagnetic. The complex impedance spectroscopic studies indicate that both 1 and 2 are semiconductors and 2 is more conducting.

  4. Electron density of states at the edge of the valence band of Cd{sub 0.88}Fe{sub 0.12}Se-A photoemission yield study

    Energy Technology Data Exchange (ETDEWEB)

    Sarem, Ammar [Department of Physics, Faculty of Science, Tishreen University, Aleppo Street, Latakia (Syrian Arab Republic)], E-mail: samers@scs-net.org; Kowalski, Bogdan J. [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL 02-668 Warsaw (Poland); Nehme, Elias Al-Khoury [Department of Physics, Faculty of Science, Tishreen University, Aleppo Street, Latakia (Syrian Arab Republic)

    2007-08-15

    The electronic structures of Cd{sub 0.88}Fe{sub 0.12}Se and CdSe have been investigated by photoemission yield spectroscopy (PYS) in the photon energy range from 5 to 12 eV. The (112-bar0) surfaces were obtained by cleavage under ultrahigh vacuum (UHV) conditions. An Fe-related emission appeared at 0.58 eV above the valence band edge. The freshly cleaved surface of Cd{sub 0.88}Fe{sub 0.12}Se interacted with ambient atmosphere more strongly than CdSe crystal. Leaving the sample in an UHV chamber at room temperature enabled us to identify surface related features and to observe decrease of the ionization energy E{sub i}, energy threshold E{sub d} and the crystal affinity {chi} due to change of the surface conditions. Effective density of states, derived from the experimental spectra of Cd{sub 0.88}Fe{sub 0.12}Se exhibits, in contrast with CdSe, a surface-related feature degenerated with the bulk valence band.

  5. Different valence Sn doping - A simple way to detect oxygen concentration variation of ZnO quantum dots synthesized under ultrasonic irradiation.

    Science.gov (United States)

    Yang, Weimin; Zhang, Bing; Zhang, Qitu; Wang, Lixi; Song, Bo; Wu, Fan; Wong, C P

    2017-09-01

    An ultrasonic method is employed to synthesize the Sn doped Zn0.95Sn0.05O quantum dots with green light emission. Sn2+ and Sn4+ ions are used to create different optical defects inside Zn0.95Sn0.05O quantum dots and the changing trend of oxygen concentration under different ultrasonic irradiation power are investigated. The photoluminescence spectra are employed to characterize the optical defects of Zn0.95Sn0.05O quantum dots. The UV-vis spectra are used to study the band gap of Zn0.95Sn0.05O quantum dots, which is influenced by their sizes. The results indicate that ultrasonic power would influence the size of Zn0.95Sn0.05O quantum dots as well as the type and quantity of defects in ZnO quantum dots. Changing trends in size of Sn2+ and Sn4+ doped Zn0.95Sn0.05O quantum dots are quite similar with each other, while the changing trends in optical defects types and concentration of Sn2+ and Sn4+ doped Zn0.95Sn0.05O quantum dots are different. The difference of the optical defects concentration changing between Sn2+ doped Zn0.95Sn0.05O quantum dots (VO defects) and Sn4+ doped Zn0.95Sn0.05O quantum dots (OZn and Oi defects) shows that the formation process of ZnO under ultrasonic irradiation wiped oxygen out. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Probing Transient Valence Orbital Changes with Picosecond Valence-to-Core X-ray Emission Spectroscopy

    DEFF Research Database (Denmark)

    March, Anne Marie; Assefa, Tadesse A.; Boemer, Christina

    2017-01-01

    valence orbitals to the nascent core-hole. Vtc-XES offers particular insight into the molecular orbitals directly involved in the light-driven dynamics; a change in the metal ligand orbital overlap results in an intensity reduction and a blue energy shift in agreement with our theoretical calculations......We probe the dynamics of valence electrons in photoexcited [Fe(terpy)2]2+ in solution to gain deeper insight into the Fe ligand bond changes. We use hard X-ray emission spectroscopy (XES), which combines element specificity and high penetration with sensitivity to orbital structure, making...... it a powerful technique for molecular studies in a wide variety of environments. A picosecond-time-resolved measurement of the complete Is X-ray emission spectrum captures the transient photoinduced changes and includes the weak valence-to-core (vtc) emission lines that correspond to transitions from occupied...

  7. Valence ionized states of iron pentacarbonyl and eta5-cyclopentadienyl cobalt dicarbonyl studied by symmetry-adapted cluster-configuration interaction calculation and collision-energy resolved Penning ionization electron spectroscopy.

    Science.gov (United States)

    Fukuda, Ryoichi; Ehara, Masahiro; Nakatsuji, Hiroshi; Kishimoto, Naoki; Ohno, Koichi

    2010-02-28

    Valence ionized states of iron pentacarbonyl Fe(CO)(5) and eta(5)-cyclopentadienyl cobalt dicarbonyl Co(eta(5)-C(5)H(5))(CO)(2) have been studied by ultraviolet photoelectron spectroscopy, two-dimensional Penning ionization electron spectroscopy (2D-PIES), and symmetry-adapted cluster-configuration interaction calculations. Theory provided reliable assignments for the complex ionization spectra of these molecules, which have metal-carbonyl bonds. Theoretical ionization energies agreed well with experimental observations and the calculated wave functions could explain the relative intensities of PIES spectra. The collision-energy dependence of partial ionization cross sections (CEDPICS) was obtained by 2D-PIES. To interpret these CEDPICS, the interaction potentials between the molecules and a Li atom were examined in several coordinates by calculations. The relation between the slope of the CEDPICS and the electronic structure of the ionized states, such as molecular symmetry and the spatial distribution of ionizing orbitals, was analyzed. In Fe(CO)(5), an attractive interaction was obtained for the equatorial CO, while the interaction for the axial CO direction was repulsive. For Co(eta(5)-C(5)H(5))(CO)(2), the interaction potential in the direction of both Co-C-O and Co-Cp ring was attractive. These anisotropic interactions and ionizing orbital distributions consistently explain the relative slopes of the CEDPICS.

  8. Intrinsic Carrier Concentration and Electron Effective Mass in Hg(1-x) Zn(x) Te

    Science.gov (United States)

    Sha, Yi-Gao; Su, Ching-Hua; Lehoczky, S. L.

    1997-01-01

    In this work, the intrinsic carrier concentration and electron effective mass in Hg(l-x)Zn(x)Te were numerically calculated. We adopt the procedures similar to those used by Su et. al. for calculating intrinsic carrier concentrations in Hg(1-x)Cd(x)Te which solve the exact dispersion relation in Kane model for the calculation of the conduction band electron concentrations and the corresponding electron effective masses. No approximation beyond those inherent in the k centered dot p model was used here.

  9. Contribution of proton and electron precipitation to the observed electron concentration in October-November 2003 and September 2005

    Energy Technology Data Exchange (ETDEWEB)

    Verronen, P.T.; Andersson, M.E.; Kauristie, K.; Palmroth, M. [Finnish Meteorological Institute, Helsinki (Finland). Earth Observation; Kero, A. [Oulu Univ., Sodankylae (Finland). Sodankylae Geophysical Observatory; Enell, C.F. [EISCAT Scientific Association, Kiruna (Sweden); Wissing, J.M. [Osnabrueck Univ. (Germany). Inst. of Environmental Systems Research; Talaat, E.R. [Johns Hopkins Univ., Laurel, MD (United States). Applied Physics Lab.; Sarris, T.E. [Democritus Univ. of Thrace, Xanthi (Greece). Space Research Lab.; Armandillo, E. [European Space Agency, Nordwijk (Netherlands). ESTEC

    2015-01-01

    Understanding the altitude distribution of particle precipitation forcing is vital for the assessment of its atmospheric and climate impacts. However, the proportion of electron and proton forcing around the mesopause region during solar proton events is not always clear due to uncertainties in satellite-based flux observations. Here we use electron concentration observations of the European Incoherent Scatter Scientific Association (EISCAT) incoherent scatter radars located at Tromsoe (69.58 N, 19.23 E) to investigate the contribution of proton and electron precipitation to the changes taking place during two solar proton events. The EISCAT measurements are compared to the results from the SodankylaeIon and Neutral Chemistry Model (SIC). The proton ionization rates are calculated by two different methods - a simple energy deposition calculation and the Atmospheric Ionization Model Osnabrueck (AIMOS v1.2), the latter providing also the electron ionization rates. Our results show that in general the combination of AIMOS and SIC is able to reproduce the observed electron concentration within 50% when both electron and proton forcing is included. Electron contribution is dominant above 90 km, and can contribute significantly also in the upper mesosphere especially during low or moderate proton forcing. In the case of strong proton forcing, the AIMOS electron ionization rates seem to suffer from proton contamination of satellite-based flux data. This leads to overestimation of modelled electron concentrations by up to 90% between 75-90 km and up to 100-150% at 70-75 km. Above 90 km, the model bias varies significantly between the events. Although we cannot completely rule out EISCAT data issues, the difference is most likely a result of the spatio-temporal fine structure of electron precipitation during individual events that cannot be fully captured by sparse in situ flux (point) measurements, nor by the statistical AIMOS model which is based upon these observations

  10. Experimental evidence of photoinduced valence change of Fe 3 in ...

    Indian Academy of Sciences (India)

    Keywords. Photorefraction; electron paramagnetic resonance of Fe3+; BaTiO3; photo-electron paramagnetic resonance. Abstract. With a view to understanding the role of photo-induced valence changes of impurities in BaTiO3 in the phenomena of photorefraction, EPR experiments were conducted under in situ HeNe laser ...

  11. Valence band electronic structure of Nb{sub 2}Pd{sub 1.2}Se{sub 5} and Nb{sub 2}Pd{sub 0.95}S{sub 5} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Lohani, H. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India); Mishra, P. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Goyal, R.; Awana, V.P.S. [National Physical Laboratory(CSIR), Dr. K. S. Krishnan Road, New Delhi 110012 (India); Sekhar, B.R., E-mail: sekhar@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India)

    2017-03-15

    We present a comparative study of our valence band photoemission results on Nb{sub 2}Pd{sub 1.2}Se{sub 5} and Nb{sub 2}Pd{sub 0.95}S{sub 5} superconductors which are supported by our DFT based electronic structure calculations. We observe that the VB spectra of both the compounds are qualitatively similar, except for some slight differences in the binding energy positions of all the features. This could be due to the unequal electronegativities of Se and S atom. The calculated density of states (DOS) reveals that the VB features are mainly composed of Pd-Se/S hybridized states. The nature of DOS originating from the distinctly coordinated Pd atoms is different. Further, various Pd-4d and Nb-4d states crossing the Fermi level (E{sub f}) signifies the multiband character of these compounds. In addition, we find a temperature dependent pseudogap in Nb{sub 2}Pd{sub 0.95}S{sub 5} which is absent in Nb{sub 2}Pd{sub 1.2}Se{sub 5}.

  12. First-Order Phase Transition in BaNi2Ge2 and the Influence of the Valence Electron Count on Distortion of the ThCr2Si2 Structure Type.

    Science.gov (United States)

    Hlukhyy, Viktor; Trots, Dmytro; Fässler, Thomas F

    2017-02-06

    Structural instability has a strong influence on the understanding of superconductivity in iron-containing 122 phases. Similar to the 122 iron-based high-temperature superconductors, the intermetallic compound BaNi2Ge2 undergoes an orthorhombic-to-tetragonal structural phase transition. The compound was prepared by arc-melting mixtures of the elements under an argon atmosphere. Single crystals were obtained by a special heat treatment in a welded tantalum ampule. The crystal structure of the compound was investigated by powder and single-crystal X-ray diffraction. Differential thermal analysis of BaNi2Ge2 showed a reversible phase transition at ca. 480 °C. In situ temperature-dependent synchrotron powder X-ray diffraction studies revealed that below 480 °C the crystal structure of BaNi2Ge2 is orthorhombic [own structure type, space group Pnma, a = 8.3852(4) Å, b = 11.3174(8) Å, and c = 4.2902(9) Å at 30 °C] and the high-temperature phase above 510 °C belongs to the tetragonal ThCr2Si2-type structure [space group I4/mmm, a = 4.2664(1) Å, and c = 11.2537(3) Å at 510 °C]. The reversible first-order low-temperature ↔ high-temperature phase transition around 480 °C is associated with distortion of the [Ni2Ge2] layer of low-temperature modification. The anisotropy of thermal expansion of the unit cell in BaNi2Ge2 was analyzed. The crystal chemistry and chemical bonding are discussed in terms of linear muffin-tin orbital band structure calculations and a topological analysis using the electron localization function. In related compounds, the level of distortion of the uncollapsed tetragonal ThCr2Si2-type structure depends on the valence electron count (VEC).

  13. Electron-energy-loss spectroscopy of plasmon excitations in concentric-shell fullerenes

    NARCIS (Netherlands)

    Henrard, L.; Malengreau, F.; Rudolf, P.; Hevesi, K.; Caudano, R.; Lambin, Ph.; Cabioc’h, Th.

    1999-01-01

    We report evidence for surface plasmon excitations in concentric-shell fullerenes. A film of these concentric-shell fullerenes with radii around 5–7 nm was produced by carbon bombardment of a silver polycrystalline target and measured by electron-energy-loss spectroscopy (EELS) in reflection

  14. Analysis of drifting electron concentration in a self-magnetically insulated ion diode

    Science.gov (United States)

    Pushkarev, A. I.; Pak, V. G.

    2015-02-01

    The drifting electron concentration in a self-magnetically insulated ion diode is analyzed using a TEMP-4M accelerator operating in a double bipolar pulse regime with the first pulse (300-600 ns and 150-200 kV) being negative and the second (120 ns and 250-300 kV) being positive. The electron concentration in the drift region is shown to be 1013-1014 cm-3. It is established that the Lorentz force acting on electrons in crossed electric and magnetic fields is 150-200 times greater than the Coulomb repulsion force, which ensures a higher electron concentration in the drift region as compared with the space charge region.

  15. Structure and heats of formation of iodine fluorides and the respective closed-shell ions from CCSD(T) electronic structure calculations and reliable prediction of the steric activity of the free-valence electron pair in ClF6-, BrF6-, and IF6-.

    Science.gov (United States)

    Dixon, David A; Grant, Daniel J; Christe, Karl O; Peterson, Kirk A

    2008-06-16

    Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for IF, IF2-, IF2+, IF3, IF4-, IF4+, IF5, IF6-, IF6+, IF7, IF8-, BrF6-, and ClF6- from coupled cluster theory [CCSD(T)] calculations with effective-core potential correlation-consistent basis sets for I. In order to achieve near chemical accuracy (+/-1 kcal/mol), three corrections were added to the complete basis set binding energies based on frozen-core coupled-cluster theory energies: a correction for core-valence effects, a correction for scalar relativistic effects, and a correction for first-order atomic spin-orbit effects. Vibrational zero-point energies were computed at the coupled-cluster level of theory except for IF6-, IF7, and IF8-. The calculated heats of formation for the neutral and ionic IFn fluorides were used to predict fluoride affinities. It is shown that high-level calculations are required to predict correctly the steric activity of the free-valence electron pair on the central atoms in IF6- (C3v), BrF6- (Oh), and ClF6- (Oh ). The vibrational spectrum of IF8- was reanalyzed, and complete mode descriptions for square-antiprismatic XF8 species of D4d symmetry are given.

  16. First-principles investigation of impurity concentration influence on bonding behavior, electronic structure and visible light absorption for Mn-doped BiOCl photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaochao; Zhao Lijun [Institute of Clean Technique for Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Fan Caimei, E-mail: fancm@163.com [Institute of Clean Technique for Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Liang Zhenhai [Institute of Clean Technique for Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Han Peide [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2012-11-01

    We performed first-principles calculation to investigate the bonding behavior, electronic structure and visible light absorption of Mn{sub x}Bi{sub 1-x}OCl (x=0, 0.0625, 0.09375 and 0.125) using density functional theory (DFT) within a plane-wave ultrasoft pseudopotential scheme. The relaxed structural parameters are consistent with the experimental results. The bonding behavior, bond orders, Mulliken charges and bond populations as well as formation energies are obtained. The calculated band structures and density of states show that Mn incorporation results in some impurity energy levels of Mn 3d states in forbidden band as well as valence band and conduction band, and that Mn 3d states, for the modest Mn doping concentration, not only can act as the capture center of excited electrons under longer wavelength light irradiation, but also may trap the photo-excited holes, improving the transfer of photo-excited carriers to the reactive sites. Our calculated optical absorption spectra exhibit that the spectral absorption edge is obviously red-shifted and extends to the visible, red and infrared light region due to the incorporation of Mn. Our calculated absorption spectra are in excellent agreement with the experimental results of Mn-doped BiOCl photocatalyst.

  17. High-entropy alloys: Interrelations between electron concentration, phase composition, lattice parameter, and properties

    Science.gov (United States)

    Gorban', V. F.; Krapivka, N. A.; Firstov, S. A.

    2017-10-01

    An analysis of more than 200 high-entropy alloys (HEA) allowed us to find interrelations between the electron concentration, phase composition, lattice parameter, and properties of solid solutions with bcc and fcc crystal lattices. Main conditions for the appearance of high-entropy chemical compounds, such as Laves, σ, and μ phases were determined. The necessary condition for the formation of 100% high-entropy σ phase is the formation of σ phase in two-component alloys for different combinations of elements, which are components of the HEA, and the electron concentration should be 6.7-7.3 electrons per atom. To form a 100% high-entropy Laves phase, the following conditions should be fulfilled: the total negative enthalpy of mixing of alloy is about -7 kJ/mol and less; the difference between the atom sizes in a pair is more than 12%; the enthalpy of the mixing of two present elements is less than -30 kJ/mol; and the average electron concentration is 6-7 electrons per atom. It was shown that the ratios of lattice parameters of solid-solution HEA, which were experimentally determined, to the lattice parameter of the most refractory metal in the HEA determine the value of the modulus of elasticity.

  18. Influence of structure defects on optical and electronic properties of icosahedral boron rich solids

    CERN Document Server

    Schmechel, R

    1999-01-01

    doped beta-rhombohedral boron by Kramers-Kronig-Analysis gives information on the main transport processes. Beside hopping conduction of localized electrons, band conduction of delocalized electrons were found. While holes in the valence band are the delocalized charge carriers in boron carbide, in vanadium doped beta-rhombohedral boron delocalized electrons in an extrinsic impurity band are suggested. Boron and boron rich solids are known to have a high concentration on intrinsic structural imperfections. From known structure data of real crystals and known band structure calculations of perfect ideal crystals a correlation between intrinsic structure defect concentration and electron deficit in the valence band is concluded. This correlation forms the basis for the following theses: 1. The electron deficit in the valence band of a perfect crystal is the driving force for the intrinsic structure defects in a real crystal. 2. The small electron deficit becomes compensated by the structure defects - this expla...

  19. Method for calculating ionic and electronic defect concentrations in y-stabilised zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, F.W. [Risoe National Lab., Materials Research Dept., Roskilde (Denmark)

    1997-10-01

    A numerical (trial and error) method for calculation of concentration of ions, vacancies and ionic and electronic defects in solids (Brouwer-type diagrams) is presented. No approximations or truncations of the set of equations describing the chemistry for the various defect regions are used. Doped zirconia and doped thoria with simultaneous presence of protonic and electronic defects are taken as examples: 7 concentrations as function of oxygen partial pressure and/or water vapour partial pressure are determined. Realistic values for the equilibrium constants for equilibration with oxygen gas and water vapour, as well as for the internal equilibrium between holes and electrons were taken from the literature. The present mathematical method is versatile - it has also been employed by the author to treat more complex systems, such as perovskite structure oxides with over- and under-stoichiometry in oxygen, cation vacancies and simultaneous presence of protons. (au) 6 refs.

  20. Valence-to-core-detected X-ray absorption spectroscopy

    DEFF Research Database (Denmark)

    Hall, Eleanor R.; Pollock, Christopher J.; Bendix, Jesper

    2014-01-01

    X-ray absorption spectroscopy (XAS) can provide detailed insight into the electronic and geometric structures of transition-metal active sites in metalloproteins and chemical catalysts. However, standard XAS spectra inherently represent an average contribution from the entire coordination...... environment with limited ligand selectivity. To address this limitation, we have investigated the enhancement of XAS features using valence-to-core (VtC)-detected XAS, whereby XAS spectra are measured by monitoring fluorescence from valence-to-core X-ray emission (VtC XES) events. VtC emission corresponds...... to transitions from filled ligand orbitals to the metal 1s core hole, with distinct energetic shifts for ligands of differing ionization potentials. VtC-detected XAS data were obtained from multiple valence emission features for a series of well-characterized Mn model compounds; taken together, these data...

  1. Quantitative Measurements of Electronically Excited CH Concentration in Normal Gravity and Microgravity Coflow Laminar Diffusion Flames

    Science.gov (United States)

    Giassi, D.; Cao, S.; Stocker, D. P.; Takahashi, F.; Bennett, B. A. V.; Smooke, M. D.; Long, M. B.

    2015-01-01

    With the conclusion of the SLICE campaign aboard the ISS in 2012, a large amount of data was made available for the analysis of the effect of microgravity on laminar coflow diffusion flames. Previous work focused on the study of sooty flames in microgravity as well as the ability of numerical models to predict its formation in a simplified buoyancy-free environment. The current work shifts the investigation to soot-free flames, putting an emphasis on the chemiluminescence emission from electronically excited CH (CH*). This radical species is of significant interest in combustion studies: it has been shown that the electronically excited CH spatial distribution is indicative of the flame front position and, given the relatively simple diagnostic involved with its measurement, several works have been done trying to understand the ability of electronically excited CH chemiluminescence to predict the total and local flame heat release rate. In this work, a subset of the SLICE nitrogen-diluted methane flames has been considered, and the effect of fuel and coflow velocity on electronically excited CH concentration is discussed and compared with both normal gravity results and numerical simulations. Experimentally, the spectral characterization of the DSLR color camera used to acquire the flame images allowed the signal collected by the blue channel to be considered representative of the electronically excited CH emission centered around 431 nm. Due to the axisymmetric flame structure, an Abel deconvolution of the line-of-sight chemiluminescence was used to obtain the radial intensity profile and, thanks to an absolute light intensity calibration, a quantification of the electronically excited CH concentration was possible. Results show that, in microgravity, the maximum flame electronically excited CH concentration increases with the coflow velocity, but it is weakly dependent on the fuel velocity; normal gravity flames, if not lifted, tend to follow the same trend

  2. Valence band structure of PDMS surface and a blend with MWCNTs: A UPS and MIES study of an insulating polymer

    Energy Technology Data Exchange (ETDEWEB)

    Schmerl, Natalya M.; Khodakov, Dmitriy A.; Stapleton, Andrew J.; Ellis, Amanda V.; Andersson, Gunther G., E-mail: gunther.andersson@flinders.edu.au

    2015-10-30

    Graphical abstract: - Highlights: • Valence electron spectroscopy was performed on an insulating polymer using different charge compensation methods. • MWCNT were embedded in PDMS and found to be the most effective method for reducing the charging of the insulating polymer. • The valence band spectrum of PDMS was obtained via MIES and UPS. • Ion scattering spectroscopy was used to determine the concentration depth profile of the PDMS in the sample. - Abstract: The use of polydimethylsiloxane (PDMS) is increasing with new technologies working toward compact, flexible and transparent devices for use in medical and microfluidic systems. Electronic characterization of PDMS and other insulating materials is difficult due to charging, yet necessary for many applications where the interfacial structure is vital to device function or further modification. The outermost layer in particular is of importance as this is the area where chemical reactions such as surface functionalization will occur. Here, we investigate the valence band structure of the outermost layer and near surface area of PDMS through the use of metastable induced photoelectron spectroscopy (MIES) paired with ultraviolet photoelectron spectroscopy (UPS). The chemical composition of the samples under investigation were measured via X-ray photoelectron spectroscopy (XPS), and the vertical distribution of the polymer was shown with neutral impact collision ion scattering spectroscopy (NICISS). Three separate methods for charge compensation are used for the samples, and their effectiveness is compared.

  3. Electron concentration and phase stability in NbCr2-based Laves phase alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-05-12

    Phase stability in NbCr{sub 2}-based transition-metal Laves phases was studied, based on the data reported for binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves polytypes were determined as followed: with e/a < 5.76, the C15 structure is stabilized; at an e/a range of 5.88--7.53, the C14 structure is stabilized; with e/a > 7.65, the C15 structure is stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of Mg-based Laves phases and transition-metal A{sub 3}B intermetallic compounds is also reviewed and compared with the present observations in transition-metal Laves phases. In order to verify the e/a/phase stability relationship experimentally, additions of Cu (with e/a = 11) were selected to replace Cr in the NbCr{sub 2} Laves phase. Experimental results for the ternary Nb-Cr-Cu system are reported and discussed in terms of the correlation between the e/a ratio and phase stability in NbCr{sub 2}-based Laves phases. A new phase was found, which has an average composition of Nb-47Cr-3Cu. Within the solubility limit, the electron concentration and phase stability relationship is obeyed in the Nb-Cr-Cu system.

  4. Effect of HF Concentration on Physical and Electronic Properties of Electrochemically Formed Nanoporous Silicon

    Directory of Open Access Journals (Sweden)

    Pushpendra Kumar

    2009-01-01

    Full Text Available The most common fabrication technique of porous silicon (PS is electrochemical etching of a crystalline silicon wafer in a hydrofluoric (HF acid-based solution. The electrochemical process allows for precise control of the properties of PS such as thickness of the porous layer, porosity, and average pore diameter. The effect of HF concentration in the used electrolyte on physical and electronic properties of PS was studied by visual color observation, measuring nitrogen sorption isotherm, field emission type scanning electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy. It was found that with decrease in HF concentration, the pore diameter increased. The PS sample with large pore diameter, that is, smaller nanocrystalline size of Si between the pores, was found to lead to a pronounced photoluminescence peak. The systematic rise of photoluminescence peak with increase of pore diameter and porosity of PS was attributed to quantum confinement. The changes in nanocrystalline porous silicon were also clearly observed by an asymmetric broadening and shift of the optical silicon phonons in Raman spectra. The change in electronic properties of PS with pore diameter suggests possibilities of use of PS material as a template for fundamental physics as well as an optical material for technological applications.

  5. Free electron concentration dependent sub-bandgap optical absorption characterization of bulk GaN crystals

    Science.gov (United States)

    Pimputkar, S.; Suihkonen, S.; Imade, M.; Mori, Y.; Speck, J. S.; Nakamura, S.

    2015-12-01

    Optical transmission measurements were performed on high quality bulk gallium nitride (GaN) crystals grown by sodium flux, hydride vapor phase epitaxy, and the ammonothermal method with varying free electron concentrations ranging from 4×1016 cm-3 to 9×1018 cm-3. The quality of the crystals was analyzed by x-ray diffraction, threading dislocation density determination, impurity concentrations, and Hall mobility measurements. The sub-bandgap absorption coefficient and index of refraction was determined based on illumination wavelengths ranging from 360 nm to 800 nm. Phonon-assisted free carrier absorption was determined to be the dominant absorption mechanism above approximately 0.1 cm-1. The absorption coefficient at 450 nm varied linearly from 0.1 cm-1 to 5 cm-1 for free electron concentrations ranging from 1×1017 cm-3 to 9×1018 cm-3. The ammonothermal GaN samples exhibited a strong defect related onset of absorption above 2.9 eV which can be explained by the presence of appreciable hydrogenated gallium vacancies having defect states close to the valance band within the electric bandgap of GaN. The presence of hydrogenated gallium vacancies was experimentally confirmed by Fourier transform infrared absorbance measurements and double hydrogenated gallium vacancy defect are speculated to be prominent in ammonothermal GaN.

  6. Role of titanium valence states in optical and electronic features of PbO-Sb{sub 2}O{sub 3}-B{sub 2}O{sub 3}:TiO{sub 2} glass alloys

    Energy Technology Data Exchange (ETDEWEB)

    Satyanarayana, T. [Department of Physics, Acharya Nagarjuna University, Nuzvid Campus, Nuzvid 521201, A.P. (India); Kityk, I.V., E-mail: Iwan.Kityk@polsl.p [Chemical Department, Silesian Technological University, ul.Strzody 9, Gliwice (Poland); Electrical Engineering Department, Technical University of Czestochowa, Al.Armii Krajowej 17/19, Czestohcowa (Poland); Ozga, K. [Chair of Public Health, Technical University of Czestochowa, Al. Armii Krajowej 36 B (Poland); Piasecki, M.; Bragiel, P. [Institute of Physics, J. Dlugosz University Czestochowa, Al. Armii Krajowej 13/15, Czestochowa (Poland); Brik, M.G. [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Ravi Kumar, V. [Department of Physics, Acharya Nagarjuna University, Nuzvid Campus, Nuzvid 521201, A.P. (India); Reshak, A.H. [Institute of Physical Biology, South Bohemia University, NoVe Hrady 37333 (Czech Republic); Veeraiah, N. [Department of Physics, Acharya Nagarjuna University, Nuzvid Campus, Nuzvid 521201, A.P. (India)

    2009-08-12

    PbO-Sb{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses mixed with different concentrations of TiO{sub 2} (ranging from 0 to 1.5 mol.%) were synthesized. The samples are characterized by X-ray diffraction, scanning electron microscopy and DSC techniques. A variety of properties, i.e. optical absorption, photoluminescence, infrared, ESR spectra, magnetic susceptibility, photo-induced birefringence (PIB) and dielectric properties (constant epsilon', loss tan delta, a.c. conductivity sigma{sub ac} over a wide range of frequency and temperature) of these glass-ceramics have been explored. The analysis of these results indicated that Ti ion surrounding ligands play principal role in the observed PIB and the sample crystallized with 0.8 mol.% of TiO{sub 2} is the most suitable for the applications in non-linear optical devices.

  7. The large-scale isolated disturbances dynamics in the main peak of electronic concentration of ionosphere

    Science.gov (United States)

    Kalinin, U. K.; Romanchuk, A. A.; Sergeenko, N. P.; Shubin, V. N.

    2003-07-01

    The vertical sounding data at chains of ionosphere stations are used to obtain relative variations of electron concentration in the F2 ionosphere region. Specific isolated traveling large-scale irregularities are distinguished in the diurnal succession of the fcF2 relative variations records. The temporal shifts of the irregularities at the station chains determine their motion velocity (of the order of speed of sound) and spatial scale (of order of 3000-5000km, the trajectory length being up to 10000km). The motion trajectories of large-scale isolated irregularities which had preceded the earthquakes are reconstructed.

  8. Electronic and magnetic properties of graphene, silicene and germanene with varying vacancy concentration

    Directory of Open Access Journals (Sweden)

    Muhammad Ali

    2017-04-01

    Full Text Available The experimental realization of two-dimensional materials such as graphene, silicene and germanene has attracted incredible interest ranging from understanding their physical properties to device applications. During the fabrication and processing of these two-dimensional materials, structural defects such as vacancies may be produced. In this work we have systemically investigated the formation energies, electronic and magnetic properties of graphene, silicene and germanene with vacancies in the framework of spin polarized density functional theory. It is found that the magnetic moment of graphene and silicene with vacancies decreases with the increase in the concentration of vacancies. However, germanene remains non-magnetic irrespective of the vacancy concentration. Low-buckled silicene and germanene with vacancies may possess remarkable band gaps, in contrast to planar graphene with vacancies. With the formation of vacancies silicene and germanene demonstrate a transition from semimetal to semiconductor, while graphene turns to be metallic.

  9. Valence band effective Hamiltonians in nitride semiconductors

    Science.gov (United States)

    Punya, Atchara; Schwertfager, Nucharee; Lambrecht, Walter

    2012-02-01

    Valence band effective Hamiltonians are useful to determine the electronic states of shallow impurities, quantum wells, quantum wires and quantum dots within the effective mass approximation. Although significant experimental and theoretical work has been performed, basic parameters such as the Rashba Sheka Pikus (RSP) Hamiltonian parameters are still uncertain. In this work, the electronic band structures of AlN, GaN and InN, all in the wurtzite crystal structure, as well as the RSP Hamiltonian parameters are determined by using the QSGW approximation in a FP-LMTO implementation. The corrections offered by this approach beyond the LDA are important to obtain the splittings and effective masses accurately. The present GW implementation, which allows for a real space representation of the self-energy, enables us to interpolate exactly to a fine k-mesh and hence to obtain accurate effective masses. We find the crystal field splitting in GaN (12 meV) in much closer agreement with experiment than previous work and obtain a negative SO coupling for InN. Moreover, we have generalized the method of invariants to crystals with orthorombic symmetry, such as ZnSiN2 ZnGeN2, ZnSnN2 and CdGeN2 and determined the corresponding Hamiltonian parameters.

  10. Multielectron coincidence spectroscopy for core-valence doubly ionized states of CO.

    Science.gov (United States)

    Hikosaka, Y; Kaneyasu, T; Shigemasa, E; Lablanquie, P; Penent, F; Ito, K

    2007-07-28

    Double photoionization into states which have holes in one core and one valence orbitals has been observed in CO using a state-of-the-art multielectron coincidence method. The core-valence CO2+ structures exhibited on the electron coincidence spectra are assigned by comparison with the available calculation [H. Schulte et al., J. Chem. Phys. 105, 11108 (1996)]. Features of the spectrum confirm that the properties of the CO2+ states are characterized by the interaction between the localized valence holes and the core holes.

  11. Role of radiative decay of valence plasmons in transmission spectra of Si, SiNx and PET membranes

    Science.gov (United States)

    Yadav, P. K.; Gupta, R. K.; Modi, M. H.; Kumar, Shailendra

    2013-03-01

    Membranes of Si, SiNx and polyethylene terephthalate (PET) were investigated via vacuum ultraviolet (VUV) transmission measurements. The transmission spectra show maxima at energies equal to energies of valence plasmons (VPs) which are interpreted as signatures of radiative decay of VPs. Resonant generation and radiative decay mechanism of valence plasmons and their effects on transmission spectra are discussed. Furthermore, the energy of VPs in SiNx was also confirmed by photo electron spectroscopy (PES) measurements on SiNx thin film. The presented results demonstrate the light induced resonant generation and radiative decay of both, valence bulk and valence surface plasmons.

  12. Electron-induced desorption of europium atoms from oxidized tungsten surface: concentration dependence of low-energy peak

    CERN Document Server

    Davydov, S Y

    2002-01-01

    One discusses nature of electron induced desorption of Eu sup 0 europium atoms under E sub e irradiating electron low-energies (approx 30 eV) and peculiarities of yield dependence of Eu sup 0 atoms on their concentration at oxidized tungsten surface. Primary act of vacancy origination in europium adatom inner 5p-shell turned to be the determining stage. Evaluations have shown that just the first of two possible scenarios of ionization (electron intra-atomic to Eu adatom external quasi-level or realise of knocked out electron into vacuum) leads to Eu sup 0 desorption. One determined concentration threshold for yield of Eu sup 0 atoms

  13. Adrenaline: communication by electron emission. Effect of concentration and temperature. Product analysis.

    Science.gov (United States)

    Getoff, Nikola; Huber, C; Hartmann, J; Huber, J C; Quint, R M

    2010-08-01

    BACKGROUND: Based on the recent findings about the ability of sexual hormones to emit electrons (e(aq) (-)) and to act as electron mediator, it was of interest to investigate adrenaline as an important neurotransmitter. MATERIALS AND METHODS: Highest purity adrenaline (ADR) and chemicals were used for preparation of aqueous solutions (pH ~7.4). The excitation of ADR in singlet state was achieved by irradiation of airfree aqueous solution with monochromatic UV light at λ = 254 nm. The emitted "solvated electrons" (e(aq) (-)) were scavenged by chloroethanol, where the quantum yield of Cl(-) ions, Q(Cl(-))=Q(e(aq) (-)). ADR degradation and formation of photolytic products were followed by HPLC analysis. RESULTS AND CONCLUSION: It was found that Q(e(aq) (-)) values decrease with increasing ADR concentration: for 2.5×10(-5) mol/L ADR was determined as Q(e(aq) (-))=6×10(-3), whereas for 1×10(-3) mol/L ADR was found to be 0.9×10(-3). This is explained by formation of associates in ground state, which consume a part of emitted e(aq) (-). As a main photolytic product aminochrome was determined.

  14. Valence-Bond Theory and Chemical Structure.

    Science.gov (United States)

    Klein, Douglas J.; Trinajstic, Nenad

    1990-01-01

    Discussed is the importance of valence bond theory on the quantum-mechanical theory of chemical structure and the nature of the chemical bond. Described briefly are early VB theory, development of VB theory, modern versions, solid-state applications, models, treatment in textbooks, and flaws in criticisms of valence bond theory. (KR)

  15. Hair mercury concentrations and associated factors in an electronic waste recycling area, Guiyu, China

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Wenqing [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China); Chen, Yaowen [Central Laboratory of Shantou University, Shantou 515063, Guangdong (China); Huang, Yue; Wang, Xiaoling [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China); Zhang, Gairong [Central Laboratory of Shantou University, Shantou 515063, Guangdong (China); Luo, Jiayi [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China); Wu, Kusheng, E-mail: kswu@stu.edu.cn [Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong (China)

    2014-01-15

    Objective: Toxic heavy metals are released to the environment constantly from unregulated electronic waste (e-waste) recycling in Guiyu, China, and thus may contribute to the elevation of mercury (Hg) and other heavy metals levels in human hair. We aimed to investigate concentrations of mercury in hair from Guiyu and potential risk factors and compared them with those from a control area where no e-waste processing occurs. Methods: A total of 285 human hair samples were collected from three villages (including Beilin, Xianma, and Huamei) of Guiyu (n=205) and the control area, Jinping district of Shantou city (n=80). All the volunteers were administered a questionnaire regarding socio-demographic characteristics and other possible factors contributed to hair mercury concentration. Hair mercury concentration was analyzed by hydride generation atomic fluorescence spectrometry (AFS). Results: Our results suggested that hair mercury concentrations in volunteers of Guiyu (median, 0.99; range, 0.18–3.98 μg/g) were significantly higher than those of Jinping (median, 0.59; range, 0.12–1.63 μg/g). We also observed a higher over-limit ratio (>1 μg/g according to USEPA) in Guiyu than in Jinping (48.29% vs. 11.25%, P<0.001). Logistic regression model showed that the variables of living house also served as an e-waste workshop, work related to e-waste, family income, time of residence in Guiyu, the distance between home and waste incineration, and fish intake were associated with hair mercury concentration. After multiple stepwise regression analysis, in the Guiyu samples, hair mercury concentration was found positively associated with the time residence in Guiyu (β=0.299, P<0.001), and frequency of shellfish intake (β=0.184, P=0.016); and negatively associated with the distance between home and waste incineration (β=−0.190, P=0.015) and whether house also served as e-waste workshop (β=−0.278, P=0.001). Conclusions: This study investigated human mercury exposure

  16. Valence and ionic lowest-lying electronic states of ethyl formate as studied by high-resolution vacuum ultraviolet photoabsorption, He(I) photoelectron spectroscopy, and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Śmiałek, M. A., E-mail: smialek@pg.gda.pl [Department of Control and Energy Engineering, Faculty of Ocean Engineering and Ship Technology, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk (Poland); Łabuda, M.; Guthmuller, J. [Department of Theoretical Physic and Quantum Information, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk (Poland); Hubin-Franskin, M.-J.; Delwiche, J. [Département de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège (Belgium); Duflot, D. [Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Université Lille1 Sciences et Technologies, F-59655 Villeneuve d' Ascq Cedex (France); Mason, N. J. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Hoffmann, S. V.; Jones, N. C. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Building 1520, DK-8000 Aarhus C (Denmark); Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2014-09-14

    The highest resolution vacuum ultraviolet photoabsorption spectrum of ethyl formate, C{sub 2}H{sub 5}OCHO, yet reported is presented over the wavelength range 115.0–275.5 nm (10.75–4.5 eV) revealing several new spectral features. Valence and Rydberg transitions and their associated vibronic series, observed in the photoabsorption spectrum, have been assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. Calculations have also been carried out to determine the ionization energies and fine structure of the lowest ionic state of ethyl formate and are compared with a newly recorded He(I) photoelectron spectrum (from 10.1 to 16.1 eV). New vibrational structure is observed in the first photoelectron band. The photoabsorption cross sections have been used to calculate the photolysis lifetime of ethyl formate in the upper stratosphere (20–50 km)

  17. Multiple paths of electron flow to current in microbial electrolysis cells fed with low and high concentrations of propionate.

    Science.gov (United States)

    Hari, Ananda Rao; Katuri, Krishna P; Gorron, Eduardo; Logan, Bruce E; Saikaly, Pascal E

    2016-07-01

    Microbial electrolysis cells (MECs) provide a viable approach for bioenergy generation from fermentable substrates such as propionate. However, the paths of electron flow during propionate oxidation in the anode of MECs are unknown. Here, the paths of electron flow involved in propionate oxidation in the anode of two-chambered MECs were examined at low (4.5 mM) and high (36 mM) propionate concentrations. Electron mass balances and microbial community analysis revealed that multiple paths of electron flow (via acetate/H2 or acetate/formate) to current could occur simultaneously during propionate oxidation regardless of the concentration tested. Current (57-96 %) was the largest electron sink and methane (0-2.3 %) production was relatively unimportant at both concentrations based on electron balances. At a low propionate concentration, reactors supplemented with 2-bromoethanesulfonate had slightly higher coulombic efficiencies than reactors lacking this methanogenesis inhibitor. However, an opposite trend was observed at high propionate concentration, where reactors supplemented with 2-bromoethanesulfonate had a lower coulombic efficiency and there was a greater percentage of electron loss (23.5 %) to undefined sinks compared to reactors without 2-bromoethanesulfonate (11.2 %). Propionate removal efficiencies were 98 % (low propionate concentration) and 78 % (high propionate concentration). Analysis of 16S rRNA gene pyrosequencing revealed the dominance of sequences most similar to Geobacter sulfurreducens PCA and G. sulfurreducens subsp. ethanolicus. Collectively, these results provide new insights on the paths of electron flow during propionate oxidation in the anode of MECs fed with low and high propionate concentrations.

  18. Multiple paths of electron flow to current in microbial electrolysis cells fed with low and high concentrations of propionate

    KAUST Repository

    Rao, Hari Ananda

    2016-03-03

    Microbial electrolysis cells (MECs) provide a viable approach for bioenergy generation from fermentable substrates such as propionate. However, the paths of electron flow during propionate oxidation in the anode of MECs are unknown. Here, the paths of electron flow involved in propionate oxidation in the anode of two-chambered MECs were examined at low (4.5 mM) and high (36 mM) propionate concentrations. Electron mass balances and microbial community analysis revealed that multiple paths of electron flow (via acetate/H2 or acetate/formate) to current could occur simultaneously during propionate oxidation regardless of the concentration tested. Current (57–96 %) was the largest electron sink and methane (0–2.3 %) production was relatively unimportant at both concentrations based on electron balances. At a low propionate concentration, reactors supplemented with 2-bromoethanesulfonate had slightly higher coulombic efficiencies than reactors lacking this methanogenesis inhibitor. However, an opposite trend was observed at high propionate concentration, where reactors supplemented with 2-bromoethanesulfonate had a lower coulombic efficiency and there was a greater percentage of electron loss (23.5 %) to undefined sinks compared to reactors without 2-bromoethanesulfonate (11.2 %). Propionate removal efficiencies were 98 % (low propionate concentration) and 78 % (high propionate concentration). Analysis of 16S rRNA gene pyrosequencing revealed the dominance of sequences most similar to Geobacter sulfurreducens PCA and G. sulfurreducens subsp. ethanolicus. Collectively, these results provide new insights on the paths of electron flow during propionate oxidation in the anode of MECs fed with low and high propionate concentrations.

  19. Nature of the concentration thresholds of europium atom yield from the oxidized tungsten surface under electron stimulated desorption

    CERN Document Server

    Davydov, S Y

    2002-01-01

    The nature of the electron-stimulated desorption (ESD) of the europium atoms by the E sub e irradiating electrons energies, equal to 50 and 80 eV, as well as peculiarities of the Eu atoms yield dependence on their concentration on the oxidized tungsten surface are discussed. It is shown, that the ESD originates by the electron transition from the interval 5p- or 5s shell of the tungsten surface atom onto the oxygen external unfilled 2p-level

  20. Valence evaluation with approaching or withdrawing cues: directly testing valence-arousal conflict theory.

    Science.gov (United States)

    Wang, Yan Mei; Li, Ting; Li, Lin

    2017-07-19

    The valence-arousal conflict theory assumes that both valence and arousal will trigger approaching or withdrawing tendencies. It also predicts that the speed of processing emotional stimuli will depend on whether valence and arousal trigger conflicting or congruent motivational tendencies. However, most previous studies have provided evidence of the interaction between valence and arousal only, and have not provided direct proof of the interactive links between valence, arousal and motivational tendencies. The present study provides direct evidence for the relationship between approach-withdrawal tendencies and the valence-arousal conflict. In an empirical test, participants were instructed to judge the valence of emotional words after visual-spatial cues that appeared to be either approaching or withdrawing from participants. A three-way interaction (valence, arousal, and approach-withdrawal tendency) was observed such that the response time was shorter if participants responded to a negative high-arousal stimulus after a withdrawing cue, or to a positive low-arousal stimulus after an approaching cue. These findings suggest that the approach-withdrawal tendency indeed plays a crucial role in valence-arousal conflict, and that the effect depends on the congruency of valence, arousal and tendency at an early stage of processing.

  1. On triangle meshes with valence dominant vertices

    KAUST Repository

    Morvan, Jean-Marie

    2018-02-16

    We study triangulations $\\\\cal T$ defined on a closed disc $X$ satisfying the following condition: In the interior of $X$, the valence of all vertices of $\\\\cal T$ except one of them (the irregular vertex) is $6$. By using a flat singular Riemannian metric adapted to $\\\\cal T$, we prove a uniqueness theorem when the valence of the irregular vertex is not a multiple of $6$. Moreover, for a given integer $k >1$, we exhibit non isomorphic triangulations on $X$ with the same boundary, and with a unique irregular vertex whose valence is $6k$.

  2. Associations of Electronic Cigarette Nicotine Concentration With Subsequent Cigarette Smoking and Vaping Levels in Adolescents.

    Science.gov (United States)

    Goldenson, Nicholas I; Leventhal, Adam M; Stone, Matthew D; McConnell, Rob S; Barrington-Trimis, Jessica L

    2017-12-01

    Research indicates that electronic cigarette (e-cigarette) use (vaping) among adolescents is associated with the initiation and progression of combustible cigarette smoking. The reasons for this association are unknown. To evaluate whether use of e-cigarettes with higher nicotine concentrations is associated with subsequent increases in the frequency and intensity of combustible cigarette smoking and vaping. In this prospective cohort study involving students from 10 high schools in the Los Angeles, California, metropolitan area, surveys were administered during 10th grade in the spring (baseline) and 11th grade in the fall (6-month follow-up) of 2015 to students who reported using e-cigarettes within the past 30 days and the nicotine concentration level they used at baseline. Self-report of baseline e-cigarette nicotine concentration of none (0 mg/mL), low (1-5 mg/mL), medium (6-17 mg/mL), or high (≥18 mg/mL) typically used during the past 30 days. Frequency of combustible cigarette smoking and e-cigarette use within the past 30 days (0 days [none], 1-2 days [infrequent], or ≥3 days [frequent]) and daily intensity of smoking and vaping (number of cigarettes smoked per day, number of vaping episodes per day, and number of puffs per vaping episode) at the 6-month follow-up. The analytic sample included 181 students (96 boys [53.0%] and 85 girls [47.0%]; mean [SD] age, 16.1 [0.4] years). Each successive increase in nicotine concentration (none to low, low to medium, and medium to high) vaped was associated with a 2.26 (95% CI, 1.28-3.98) increase in the odds of frequent (vs no) smoking and a 1.65 (95% CI, 1.09-2.51) increase in the odds of frequent (vs no) vaping at follow-up after adjustment for baseline frequency of smoking and vaping and other relevant covariates. Use of e-cigarettes with high (vs no) nicotine concentration was associated with a greater number of cigarettes smoked per day at follow-up (adjusted rate ratio [RR], 7.03; 95% CI, 6.11-7.95). An

  3. Relativistic Multireference Many-body Perturbation Theory for Open-shell Ions with Multiple Valence Shell Electrons: the Transition Rates and Lifetimes of the Excited Levels in Chlorinelike Fe X

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Y; Santana, J A; Trabert, E

    2009-09-30

    A recently developed relatistic multireference many-body perturbation theory based on multireference configuration-interaction wavefunctions as zeroth order wavefunctions is outlined. The perturbation theory employs a general class of configuration-interaction wve functions as reference functions, and thus is applciable to multiple open valence shell systems with near degeneracy of a manifold of strongly interacting configurations. Multireference many-body perturbation calculations are reported for the ground and excited states of chlorine-like Fe X in which the near degeneracy of a manifold of strongly interacting configurations mandates a multireference treatment. Term energies of a total of 83 excited levels arising from the 3s{sup 2}3p{sup 5}, 3s3p{sup 6}, 3s{sup 2}3p{sup 4}3d, 3s3p{sup 5}3d, and 3s{sup 2}3p{sup 3}3d{sup 2} configurations of the ion are evaluated to high accuracy. Transition rates associated with E1/M1/E2/M2/E3 radiative decays and lifetimes of a number of excited levels are calculated and compared with laboratory measurements to critically evaluate recent experiments.

  4. Perception of emotional valence in horse whinnies.

    Science.gov (United States)

    Briefer, Elodie F; Mandel, Roi; Maigrot, Anne-Laure; Briefer Freymond, Sabrina; Bachmann, Iris; Hillmann, Edna

    2017-01-01

    Non-human animals often produce different types of vocalisations in negative and positive contexts (i.e. different valence), similar to humans, in which crying is associated with negative emotions and laughter is associated with positive ones. However, some types of vocalisations (e.g. contact calls, human speech) can be produced in both negative and positive contexts, and changes in valence are only accompanied by slight structural differences. Although such acoustically graded signals associated with opposite valence have been highlighted in some species, it is not known if conspecifics discriminate them, and if contagion of emotional valence occurs as a result. We tested whether domestic horses perceive, and are affected by, the emotional valence of whinnies produced by both familiar and unfamiliar conspecifics. We measured physiological and behavioural reactions to whinnies recorded during emotionally negative (social separation) and positive (social reunion) situations. We show that horses perceive acoustic cues to both valence and familiarity present in whinnies. They reacted differently (respiration rate, head movements, height of the head and latency to respond) to separation and reunion whinnies when produced by familiar, but not unfamiliar individuals. They were also more emotionally aroused (shorter inter-pulse intervals and higher locomotion) when hearing unfamiliar compared to familiar whinnies. In addition, the acoustic parameters of separation and reunion whinnies affected the physiology and behaviour of conspecifics in a continuous way. However, we did not find clear evidence for contagion of emotional valence. Horses are thus able to perceive changes linked to emotional valence within a given vocalisation type, similar to perception of affective prosody in humans. Whinnies produced in either separation or reunion situations seem to constitute acoustically graded variants with distinct functions, enabling horses to increase their apparent vocal

  5. Electron spin resonance microscopic imaging of oxygen concentration in cancer spheroids

    Science.gov (United States)

    Hashem, Mada; Weiler-Sagie, Michal; Kuppusamy, Periannan; Neufeld, Gera; Neeman, Michal; Blank, Aharon

    2015-07-01

    Oxygen (O2) plays a central role in most living organisms. The concentration of O2 is important in physiology and pathology. Despite the importance of accurate knowledge of the O2 levels, there is very limited capability to measure with high spatial resolution its distribution in millimeter-scale live biological samples. Many of the current oximetric methods, such as oxygen microelectrodes and fluorescence lifetime imaging, are compromised by O2 consumption, sample destruction, invasiveness, and difficulty to calibrate. Here, we present a new method, based on the use of the pulsed electron spin resonance (ESR) microimaging technique to obtain a 3D mapping of oxygen concentration in millimeter-scale biological samples. ESR imaging requires the incorporation of a suitable stable and inert paramagnetic spin probe into the desirable object. In this work, we use microcrystals of a paramagnetic spin probe in a new crystallographic packing form (denoted tg-LiNc-BuO). These paramagnetic species interact with paramagnetic oxygen molecules, causing a spectral line broadening that is linearly proportional to the oxygen concentration. Typical ESR results include 4D spatial-spectral images that give an indication about the oxygen concentration in different regions of the sample. This new oximetry microimaging method addresses all the problems mentioned above. It is noninvasive, sensitive to physiological oxygen levels, and easy to calibrate. Furthermore, in principle, it can be used for repetitive measurements without causing cell damage. The tissue model used in this research is spheroids of Human Colorectal carcinoma cell line (HCT-116) with a typical diameter of ∼600 μm. Most studies of the microenvironmental O2 conditions inside such viable spheroids carried out in the past used microelectrodes, which require an invasive puncturing of the spheroid and are also not applicable to 3D O2 imaging. High resolution 3D oxygen maps could make it possible to evaluate the

  6. Major and Trace Element Concentrations in Garnet Performed by Electron Microprobe and MicroPIXE

    Science.gov (United States)

    Borghi, A.; Cossio, R.; Mazzoli, C.; Olmi, F.; Vaggelli, G.

    2003-12-01

    The chemical composition of rock-forming minerals reflects their crystallisation history and provides information on the temperature and pressure conditions during their formation. Among metamorphic minerals, garnet is one of the most commonly studied in metamorphic petrology because a chemical zoning is often observed in porphyroblasts that potentially records the changes in the reaction history of the rock. In the past, only major element composition could be determined by non-destructive analytical procedure. However, at high temperature major element growth zoning may be significantly modified by intra-crystalline diffusion. Consequently, the study of trace elements distribution, which may be less susceptible to diffusional modification, becomes of fundamental importance. In this regard, an inverse correlation between yttrium concentration in garnet and metamorphic grade has been recently proposed for pelitic rocks (Pyle & Spear, 2000). This coupling is of great advantage as it may be used to calibrate new geothermometers based on exchange equilibria involving trace elements in garnet In the present paper, a micro-beam Proton Induced X-Ray Emission (micro-PIXE) analytical technique and a WDS electron microprobe (EPMA), were been applied to a specific geological problem particularly affected by the limitations of other techniques. The collected samples come from meta-pelitic samples belonging to the tectonic unit of Monte Rosa Nappe (Western Alps). Selected garnet crystals were analysed for major (Si, Al, Mg, Ca, Mn, Fe) and trace elements. The former were analysed by EPMA and the latter by micro-PIXE. The considered garnet crystals show well-defined compositional zoning, characterised by a smooth and concentric variation of the selected elements from core to rim. As regards the trace elements distribution, the two-dimensional X-ray maps display a strong Y enrichment in the core, followed by a flat pattern at the inner and outer rim. Y concentration spreads over

  7. A study of magnetic and spectroscopic properties of Fe(II)Fe(III)2O(CH3CO2)6L3, L=H2O or C5H5N. Direct observation of the thermal barrier to electron transfer in a mixed valence complex

    Science.gov (United States)

    Dziobkowski, C. T.; Wrobleski, J. T.; Brown, D. B.

    1980-10-01

    The mixed-valence iron (2, 3, 3) acetates, (Fe3O(CH3CO2)6L3), where L = water or pyridine, have been prepared and studied by Mossbauer, infrared, and optical spectroscopy and magnetic susceptibility methods. Variable-temperature magnetic susceptibility data for the aquo complex are interpreted on the basis of HDVV S2 = 2, S1 = S3 = 5/2 spin exchange model with J12 = j23 = 1/-50 cm and J13 = 1/14.5 cm. An intervalence transfer band is observed at 1/138000 cm in the room temperature electronic spectrum of the aquo complex. Mossbauer spectra of these compounds are markedly temperature dependent. At 17K absorptions due to distinct Fe(2) and Fe(3) sites are observed while at 300 K a single absorption is observed. Spectra at intermediate temperatures are modeled by assuming intratrimer electronic relaxation between pairs of iron ions. The activation energy for relaxation derived from this model is 1/470 cm for the aquo complex. This energy is equal to the barrier to intramolecular, intervalence thermal electron transfer.

  8. Altitude distribution of electron concentration in ionospheric D-region in presence of time-varying solar radiation flux

    Energy Technology Data Exchange (ETDEWEB)

    Nina, A., E-mail: sandrast@ipb.ac.rs [Institute of Physics, University of Belgrade, P.O. Box 57, Belgrade (Serbia); Cadez, V. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia); Sreckovic, V. [Institute of Physics, University of Belgrade, P.O. Box 57, Belgrade (Serbia); Sulic, D. [Faculty of Ecology and Environmental Protection, Union - Nikola Tesla University, Cara Dusana 62, 11000 Belgrade (Serbia)

    2012-05-15

    In this paper, we study the influence of solar flares on electron concentration in the terrestrial ionospheric D-region by analyzing the amplitude and phase time variations of very low frequency (VLF) radio waves emitted by DHO transmitter (Germany) and recorded by the AWESOME receiver in Belgrade (Serbia) in real time. The rise of photo-ionization rate in the ionospheric D-region is a typical consequence of solar flare activity as recorded by GOES-15 satellite for the event on March 24, 2011 between 12:01 UT and 12:11 UT. At altitudes around 70 km, the photo-ionization and recombination are the dominant electron gain and electron loss processes, respectively. We analyze the relative contribution of each of these two processes in the resulting electron concentration variation in perturbed ionosphere.

  9. Electronic Cereal.

    Science.gov (United States)

    Frentrup, Julie R.; Phillips, Donald B.

    1996-01-01

    Describes activities that use Froot Loops breakfast cereal to help students master the concepts of valence electrons and chemical bonding and the implications of the duet and octet rules. Involves students working in groups to create electron dot structures for various compounds. (JRH)

  10. DFT calculation of core- and valence-shell electron excitation and ionization energies of 2,1,3-benzothiadiazole C{sub 6}H{sub 4}SN{sub 2}, 1,3,2,4-benzodithiadiazine C{sub 6}H{sub 4}S{sub 2}N{sub 2}, and 1,3,5,2,4-benzotrithiadiazepine C{sub 6}H{sub 4}S{sub 3}N{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Takahata, Yuji, E-mail: taka@iqm.unicamp.br [Amazonas State University, Av. Darcy Vargas, 1200, Parque 10, 69065-020 Manaus, AM (Brazil); Institute of Chemistry, University of Campinas - UNICAMP, 13084-862 Campinas, SP (Brazil); Chong, Delano P. [Department of Chemistry, 2036 Main Mall, University of British Columbia, Vancouver, BC, Canada V6T 1Z1 (Canada)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer DFT calculations resulted average error of 0.14 eV for VIP, and 0.4 for CEBE. Black-Right-Pointing-Pointer The multiplet approximation (MA) resulted average error of 0.56 eV for core excitation energies. Black-Right-Pointing-Pointer A shifted energy method to calculated core-electron excitation energy was proposed. Black-Right-Pointing-Pointer The method is based on a combination between MA and TDDFT. Black-Right-Pointing-Pointer Convoluted spectra reproduce observed spectra in low energy region. -- Abstract: The vertical core- and valence-shell electron excitation and ionization energies of the three title molecules, 1-3, were calculated by density functional theory (DFT) using adequate functional for each type of processes and atoms under study. The inner shells treated were C1s, N1s, S1s, S2s, S2p. Molecular geometry was optimized by DFT B3LYP/6-311 + (d,p). The basis set of triple zeta plus polarization (TZP) Slater-type orbitals was employed for DFT calculations. The {Delta}SCF method was used to calculate ionization energies. The average absolute deviation (AAD) from experiment of 26 valence-electron ionization energies calculated by DFT for the three molecules 1-3 was 0.14 eV; while that of 24 calculated core-electron binding energies (CEBEs) from experiment was 0.4 eV. Selected core excitation energies were calculated by the multiplet approximation for the three molecules. The AAD of twelve calculated core excitation energies by the multiplet approximation that exclude S2s cases was 0.56 eV. Time-dependent DFT (TDDFT) was employed to calculate the excitation energies and corresponding oscillator strengths of core- and valence-electrons of the molecules. Some selected occupied core orbitals were used to calculate the core-excitation energies with the TDDFT (Sterner-Frozoni-Simone scheme). The core excitation energies thus calculated were in an average error of ca. 28 eV compared to observed values. They were shifted

  11. Generation of Kekule valence structures and the corresponding valence bond wave function

    NARCIS (Netherlands)

    Rashid, Z.; van Lenthe, J.H.

    2010-01-01

    A new scheme, called “list of nonredundant bonds”, is presented to record the number of bonds and their positions for the atoms involved in Kekulé valence structures of (poly)cyclic conjugated systems. Based on this scheme, a recursive algorithm for generating Kekulé valence structures has been

  12. The use of symmetrized valence and relative motion coordinates for crystal potentials

    DEFF Research Database (Denmark)

    McMurry, H. L.; Hansen, Flemming Yssing

    1980-01-01

    Symmetrized valence coordinates are linear combinations of conventional valence coordinates which display the symmetry of a set of atoms bound by the valence bonds. Relative motion coordinates are relative translations, or relative rotations, of two or more strongly bonded groups of atoms among...... which relatively weak forces act. They are useful for expressing interactions between molecules in molecular crystals and should be chosen, also, to reflect the symmetry of the interacting groups. Since coordinates defined by these procedures possess elements of symmetry in common with the bonding...... electron distributions, the force constants in the potential should be more amenable to calculation in terms of energy changes in the electronic ground state which accompany displacements of the atoms from equilibrium. It is easier to determine force constants for fitting experimental data because...

  13. Electronic cigarette user plasma nicotine concentration, puff topography, heart rate, and subjective effects: Influence of liquid nicotine concentration and user experience.

    Science.gov (United States)

    Hiler, Marzena; Breland, Alison; Spindle, Tory; Maloney, Sarah; Lipato, Thokozeni; Karaoghlanian, Nareg; Shihadeh, Alan; Lopez, Alexa; Ramôa, Carolina; Eissenberg, Thomas

    2017-10-01

    Electronic cigarette (ECIG) nicotine delivery and other effects may depend on liquid nicotine concentration and user experience. This study is the first to systematically examine the influence of ECIG liquid nicotine concentration and user experience on nicotine delivery, heart rate, puff topography, and subjective effects. Thirty-three ECIG-experienced individuals and 31 ECIG-naïve cigarette smokers completed 4 laboratory conditions consisting of 2, 10-puff bouts (30-sec interpuff interval) with a 3.3-V ECIG battery attached to a 1.5-Ω "cartomizer" (7.3 W) filled with 1 ml ECIG liquid. Conditions differed by liquid nicotine concentration: 0, 8, 18, or 36 mg/ml. Participants' plasma nicotine concentration was directly related to liquid nicotine concentration and dependent on user experience, with significantly higher mean plasma nicotine increases observed in ECIG-experienced individuals relative to ECIG-naïve smokers in each active nicotine condition. When using 36 mg/ml, mean plasma nicotine increase for ECIG-experienced individuals was 17.9 ng/ml (SD = 17.2) and 6.9 (SD = 7.1; p users: collapsed across condition, mean puff duration was 5.6 sec (SD = 3.0) for ECIG-experienced and 2.9 (SD = 1.5) for ECIG-naïve individuals. ECIG use also suppressed nicotine/tobacco abstinence symptoms in both groups; the magnitude of abstinence symptom suppression depended on liquid nicotine concentration and user experience. These and other recent results suggest that policies intended to limit ECIG nicotine delivery will need to account for factors in addition to liquid nicotine concentration (e.g., device power and user behavior). (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  14. Affective Priming with Associatively Acquired Valence

    Science.gov (United States)

    Aguado, Luis; Pierna, Manuel; Saugar, Cristina

    2005-01-01

    Three experiments explored the effect of affectively congruent or incongruent primes on evaluation responses to positive or negative valenced targets (the "affective priming" effect). Experiment 1 replicated the basic affective priming effect with Spanish nouns: reaction time for evaluative responses (pleasant/unpleasant) were slower on…

  15. Cesium's Off-the-Map Valence Orbital

    NARCIS (Netherlands)

    Goesten, Maarten G.; Rahm, Martin; Bickelhaupt, F. Matthias; Hensen, Emiel J.M.

    2017-01-01

    The Td-symmetric [CsO4]+ ion, featuring Cs in an oxidation state of 9, is computed to be a minimum. Cs uses outer core 5s and 5p orbitals to bind the oxygen atoms. The valence Cs 6s orbital lies too high to be involved in bonding, and contributes to Rydberg levels only. From a molecular orbital

  16. Unusual valence, negative charge-transfer gaps and self-doping in transition-metal compounds

    NARCIS (Netherlands)

    Khomskii, D. I.

    2001-01-01

    Abstract: In this paper I discuss the electronic structure and properties of a specific, rather unconventional class of transition metal (TM) compounds, e.g. TM oxides, which formally have unusually high values of the oxidation state, or valence, of TM. In contrast to the typical situation, in this

  17. Reducing the negative valence of stressful memories through emotionally valenced, modality-specific tasks

    NARCIS (Netherlands)

    Tadmor, Avia; McNally, Richard J; Engelhard, Iris M

    2016-01-01

    BACKGROUND AND OBJECTIVES: People who perform a cognitively demanding secondary task while recalling a distressing memory often experience the memory as less emotional, vivid, or accurate during subsequent recollections. In this experiment, we tested whether the emotional valence (positive versus

  18. Valence photoelectron spectra of alkali bromides calculated within the propagator theory

    DEFF Research Database (Denmark)

    Karpenko, Alexander; Iablonskyi, Denys; Aksela, Helena

    2013-01-01

    The valence ionization spectra covering the binding energy range 0-45 eV of alkali bromide XBr (X = Li, Na, K, Rb) vapors are studied within the framework of the propagator theory. Relativistic Algebraic Diagrammatic Construction calculations have been carried out in order to investigate photoion......The valence ionization spectra covering the binding energy range 0-45 eV of alkali bromide XBr (X = Li, Na, K, Rb) vapors are studied within the framework of the propagator theory. Relativistic Algebraic Diagrammatic Construction calculations have been carried out in order to investigate...... photoionization processes and to describe molecular electronic structure. Theoretical results are compared with available experimental data....

  19. Cross sections of EUV PAGs: influence of concentration, electron energy, and structure

    Science.gov (United States)

    Grzeskowiak, Steven; Narasimhan, Amrit; Wisehart, Liam; Schad, Jonathon; Neisser, Mark; Ocola, Leonidas E.; Brainard, Robert L.; Denbeaux, Greg

    2016-03-01

    Optimizing the photochemistry of extreme ultraviolet (EUV) photoresists should provide faster, more efficient resists which would lead to greater throughput in manufacturing. The fundamental reaction mechanisms in EUV resists are believed to be due to interactions with energetic electrons liberated by ionization. Identifying the likelihood (or cross section) of how these photoelectrons interact with resist components is critical to optimizing the performance of EUV resists. Chemically amplified resists utilize photoacid generators (PAGs) to improve sensitivity; measuring the cross section of electron induced decomposition of different PAGs will provide insight into developing new resist materials. To study the interactions of photoelectrons generated by EUV absorption, photoresists were exposed to electron beams at energies between 80 and 250 eV. The reactions between PAG molecules and electrons were measured using a mass spectrometer to monitor the levels of small molecules produced by PAG decomposition that outgassed from the film. Comparing the cross sections of a variety of PAG molecules can provide insight into the relationship between chemical structure and reactivity to the electrons in their environments. This research is a part of a larger SEMATECH research program to understand the fundamentals of resist exposures to help in the development of new, better performing EUV resists.

  20. A low-temperature study of manganese-induced ferromagnetism and valence band convergence in tin telluride

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Hang, E-mail: chihang@bnl.gov [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Tan, Gangjian; Kanatzidis, Mercouri G. [Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States); Li, Qiang [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Uher, Ctirad [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2016-05-02

    SnTe is renowned for its promise in advancing energy-related technologies based on thermoelectricity and for its topological crystalline insulator character. Here, we demonstrate that each Mn atom introduces ∼4 μ{sub B} (Bohr magneton) of magnetic moment to Sn{sub 1−x}Mn{sub x}Te. The Curie temperature T{sub C} reaches ∼14 K for x = 0.12, as observed in the field dependent hysteresis of magnetization and the anomalous Hall effect. In accordance with a modified two-band electronic Kane model, the light L-valence-band and the heavy Σ-valence-band gradually converge in energy with increasing Mn concentration, leading to a decreasing ordinary Hall coefficient R{sub H} and a favorably enhanced Seebeck coefficient S at the same time. With the thermal conductivity κ lowered chiefly via point defects associated with the incorporation of Mn, the strategy of Mn doping also bodes well for efficient thermoelectric applications at elevated temperatures.

  1. Direct observation of heterogeneous valence state in Yb-based quasicrystalline approximants

    Science.gov (United States)

    Matsunami, M.; Oura, M.; Tamasaku, K.; Ishikawa, T.; Ideta, S.; Tanaka, K.; Takeuchi, T.; Yamada, T.; Tsai, A. P.; Imura, K.; Deguchi, K.; Sato, N. K.; Ishimasa, T.

    2017-12-01

    We study the electronic structure of Tsai-type cluster-based quasicrystalline approximants, Au64Ge22Yb14 (AGY-I), Au63.5Ge20.5Yb16 (AGY-II), and Zn85.4Yb14.6 (Zn-Yb), by means of photoemission spectroscopy. In the valence band hard x-ray photoemission spectra of AGY-II and Zn-Yb, we separately observe a fully occupied Yb 4 f state and a valence fluctuation derived Kondo resonance peak, reflecting two inequivalent Yb sites, a single Yb atom in the cluster center and its surrounding Yb icosahedron, respectively. The fully occupied 4 f signal is absent in AGY-I containing no Yb atom in the cluster center. The results provide direct evidence for a heterogeneous valence state in AGY-II and Zn-Yb.

  2. The effect of C atom concentration on the electronic properties of ...

    Indian Academy of Sciences (India)

    G(E)]. (2). The coupling matrices 1(E) = 2(E) = (E) are minus the imaginary part of the nano- tube self-energy. (E) = i( (E) = +(E)). (3). Here, E and G(E) are the electron energy and the modified Green's function of the nanotube, respectively.

  3. The effect of C atom concentration on the electronic properties of ...

    Indian Academy of Sciences (India)

    Author Affiliations. H Milani Moghaddam1 2 3 4. Department of Physics, University of Mazandaran, Babolsar, Iran; Molecular Electronics Lab., University of Mazandaran, Babolsar, Iran; Nano and Biotechnology Research Group, University of Mazandaran, Babolsar, Iran; Nanotechnology group, Hariri Scientific Foundation, ...

  4. Quantification of the methane concentration using anaerobic oxidation of methane coupled to extracellular electron transfer

    Science.gov (United States)

    A biofilm anode acclimated with acetate, acetate+methane, and methane growth media for over three years produced a steady current density of 1.6-2.3 mA/m^2 in a microbial electrochemical cell (MxC) fed with methane as the sole electron donor. Geobacter was the dominant genus for...

  5. Valence-Dependent Belief Updating: Computational Validation

    Directory of Open Access Journals (Sweden)

    Bojana Kuzmanovic

    2017-06-01

    Full Text Available People tend to update beliefs about their future outcomes in a valence-dependent way: they are likely to incorporate good news and to neglect bad news. However, belief formation is a complex process which depends not only on motivational factors such as the desire for favorable conclusions, but also on multiple cognitive variables such as prior beliefs, knowledge about personal vulnerabilities and resources, and the size of the probabilities and estimation errors. Thus, we applied computational modeling in order to test for valence-induced biases in updating while formally controlling for relevant cognitive factors. We compared biased and unbiased Bayesian models of belief updating, and specified alternative models based on reinforcement learning. The experiment consisted of 80 trials with 80 different adverse future life events. In each trial, participants estimated the base rate of one of these events and estimated their own risk of experiencing the event before and after being confronted with the actual base rate. Belief updates corresponded to the difference between the two self-risk estimates. Valence-dependent updating was assessed by comparing trials with good news (better-than-expected base rates with trials with bad news (worse-than-expected base rates. After receiving bad relative to good news, participants' updates were smaller and deviated more strongly from rational Bayesian predictions, indicating a valence-induced bias. Model comparison revealed that the biased (i.e., optimistic Bayesian model of belief updating better accounted for data than the unbiased (i.e., rational Bayesian model, confirming that the valence of the new information influenced the amount of updating. Moreover, alternative computational modeling based on reinforcement learning demonstrated higher learning rates for good than for bad news, as well as a moderating role of personal knowledge. Finally, in this specific experimental context, the approach based on

  6. Nicotine concentrations with electronic cigarette use: effects of sex and flavor.

    Science.gov (United States)

    Oncken, Cheryl A; Litt, Mark D; McLaughlin, Lynn D; Burki, Nausherwan A

    2015-04-01

    This study examined overall changes in nicotine concentrations when using a popular e-cigarette and 18 mg/mL nicotine e-Juice, and it further explored effects of sex and flavorings on these concentrations. We recruited nontreatment-seeking smokers who were willing to try e-cigarettes for 2 weeks and abstain from cigarette smoking. Subjects were randomized to either menthol tobacco or non-menthol tobacco-flavored e-cigarette use for 7-10 days, and the next week they were crossed over to the other condition. On the last day of e-cigarette use of each flavor, subjects completed a laboratory session in which they used the e-cigarette for 5 min ad libitum. Nicotine concentrations were obtained 5 min before and 5, 10, 15, 20, and 30 min after the onset of e-cigarette use. Twenty subjects completed at least 1 monitoring session. Nicotine concentrations significantly increased from baseline to 5 min by 4 ng/mL at the first laboratory session (p e-cigarette as less likeable (p e-cigarette use for 5 min, and flavor may impact nicotine concentrations with e-cigarette use in women. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Janus Nematic Colloids with Designable Valence

    Directory of Open Access Journals (Sweden)

    Simon Čopar

    2014-05-01

    Full Text Available Generalized Janus nematic colloids based on various morphologies of particle surface patches imposing homeotropic and planar surface anchoring are demonstrated. By using mesoscopic numerical modeling, multiple types of Janus particles are explored, demonstrating a variety of novel complex colloidal structures. We also show binding of Janus particles to a fixed Janus post in the nematic cell, which acts as a seed and a micro-anchor for the colloidal structure. Janus colloidal structures reveal diverse topological defect configurations, which are effectively combinations of surface boojum and bulk defects. Topological analysis is applied to defects, importantly showing that topological charge is not a well determined topological invariant in such patchy nematic Janus colloids. Finally, this work demonstrates colloidal structures with designable valence, which could allow for targeted and valence-conditioned self-assembly at micro- and nano-scale.

  8. Evaluative conditioning induces changes in sound valence

    Directory of Open Access Journals (Sweden)

    Anna C. Bolders

    2012-04-01

    Full Text Available Evaluative Conditioning (EC has hardly been tested in the auditory domain, but it is a potentially valuable research tool. In Experiment 1 we investigated whether the affective evaluation of short environmental sounds can be changed using affective words as unconditioned stimuli (US. Congruence effects on an affective priming task (APT for conditioned sounds demonstrated successful EC. Subjective ratings for sounds paired with negative words changed accordingly. In Experiment 2 we investigated whether the acquired valence remains stable after repeated presentation of the conditioned sound without the US or whether extinction occurs. The acquired affective value remained present, albeit weaker, even after 40 extinction trials. These results warrant the use of EC to study processing of short environmental sounds with acquired valence, even if this requires repeated stimulus presentations. This paves the way for studying processing of affective environmental sounds while effectively controlling low level-stimulus properties.

  9. Human Amygdala Represents the Complete Spectrum of Subjective Valence

    Science.gov (United States)

    Jin, Jingwen; Zelano, Christina; Gottfried, Jay A.

    2015-01-01

    Although the amygdala is a major locus for hedonic processing, how it encodes valence information is poorly understood. Given the hedonic potency of odor stimuli and the amygdala's anatomical proximity to the peripheral olfactory system, we combined high-resolution fMRI with pattern-based multivariate techniques to examine how valence information is encoded in the amygdala. Ten human subjects underwent fMRI scanning while smelling 9 odorants that systematically varied in perceived valence. Representational similarity analyses showed that amygdala codes the entire dimension of valence, ranging from pleasantness to unpleasantness. This unidimensional representation significantly correlated with self-reported valence ratings but not with intensity ratings. Furthermore, within-trial valence representations evolved over time, prioritizing earlier differentiation of unpleasant stimuli. Together, these findings underscore the idea that both spatial and temporal features uniquely encode pleasant and unpleasant odor valence in the amygdala. The availability of a unidimensional valence code in the amygdala, distributed in both space and time, would create greater flexibility in determining the pleasantness or unpleasantness of stimuli, providing a mechanism by which expectation, context, attention, and learning could influence affective boundaries for guiding behavior. SIGNIFICANCE STATEMENT Our findings elucidate the mechanisms of affective processing in the amygdala by demonstrating that this brain region represents the entire valence dimension from pleasant to unpleasant. An important implication of this unidimensional valence code is that pleasant and unpleasant valence cannot coexist in the amygdale because overlap of fMRI ensemble patterns for these two valence extremes obscures their unique content. This functional architecture, whereby subjective valence maps onto a pattern continuum between pleasant and unpleasant poles, offers a robust mechanism by which context

  10. Equilibrium gels of limited valence colloids

    OpenAIRE

    Sciortino, Francesco; Zaccarelli, Emanuela

    2017-01-01

    Gels are low-packing arrested states of matter which are able to support stress. On cooling, limited valence colloidal particles form open networks stabilized by the progressive increase of the interparticle bond lifetime. These gels, named equilibrium gels, are the focus of this review article. Differently from other types of colloidal gels, equilibrium gels do not require an underlying phase separation to form. Oppositely, they form in a region of densities deprived of thermodynamic instabi...

  11. 5th International Conference on Valence Fluctuations

    CERN Document Server

    Malik, S

    1987-01-01

    During the Koln meeting (August 28-31, 1984), Irdia was chosen as the venue for the next International Conference on Valence Fluctuations. lhis was in recognition ard appreciation of the work done, both experimental ard theoretical, by the Irdian scientists in this area during the last decade. We decided to hold this Conference in the month of January, 1987 at Bangalore. lhe subject of Valence Fluctuations has kept itself alive ard active as it has provided many shocks ard suprises particularly among the Ce- ard U-based intermetallies. lhe richness of many interesting physical phenomena occurring in mixed valent materials, the flexibility of modifying their physical properties (by alloying, for example) ard the possibility of synthesizing a wide variety of new such materials seem to be the key factors in this regard. Barely six months before this Conference, an International Conference on Anomalous Rare Earths and Actinides (ICAREA) had been held at Grenoble (July, 1986) which also focussed on mixed valence a...

  12. Experimental Constraints on the Partitioning and Valence of V and Cr in Garnet and Coexisting Glass

    Science.gov (United States)

    Righter, K.; Sutton, S.; Berthet, S.; Newville, M.

    2008-01-01

    A series of experiments with garnet and coexisting melt have been carried out across a range of oxygen fugacities (near hematite-magnetite (HM) to below the iron-wustite (IW) buffers) at 1.7 GPa to study the partitioning and valence of Cr and V in both phases. Experiments were carried out in a non end loaded piston cylinder apparatus, and the run products were analyzed with electron microprobe and xray absorption near edge structure (XANES) analysis at beamline 13-ID at the Advanced Photon Source of Argonne National Lab. The valence of vanadium and chromium were determined using the position and intensity of the Ka pre-edge peaks, calibrated on a series of Cr and Vbearing standard glasses. This technique has been applied to V and Cr in glasses and V in spinels previously, and in these isotropic phases there are no orientational effects on the XANES spectra (Righter et al., 2006, Amer. Mineral. 91, 1643-1656). We also now demonstrate this to be true for V and Cr in garnet. Also, previous work has shown that V has a higher valence in the glass (or melt) than in the coexisting spinel. This is also true for V in garnet-glass pairs in this study. Vanadium valence in garnets varies from 2.7 below the IW buffer to 3.7 near HM, and for coexisting glass it varies from 3.2 to 4.3. Vanadium valence measured in some natural garnets from mantle localities indicates V in the more reduced range at 2.5. Comparisons will be made between fO2 estimated from V valence and other methods for garnet-bearing mantle samples. In contrast, Cr valence measured in garnet and coexisting glass for all experimental and natural samples is 2.9- 3.0, suggesting that the valence of Cr does not vary within either phase across a large fO2 range. These results demonstrate that while V varies from 2+ to 3+ to 4+ in garnet-melt systems, Cr does not, and this will ultimately affect the partitioning behavior of these two elements in natural systems. Garnet/melt D(Cr) are between 12 and 17 across this range

  13. An experimental and theoretical study of core-valence double ionisation of acetaldehyde (ethanal).

    Science.gov (United States)

    Zagorodskikh, S; Vapa, M; Vahtras, O; Zhaunerchyk, V; Mucke, M; Eland, J H D; Squibb, R J; Linusson, P; Jänkälä, K; Ågren, H; Feifel, R

    2016-01-28

    Core-valence double ionisation spectra of acetaldehyde (ethanal) are presented at photon energies above the carbon and oxygen 1s ionisation edges, measured by a versatile multi-electron coincidence spectroscopy technique. We use this molecule as a testbed for analyzing core-valence spectra by means of quantum chemical calculations of transition energies. These theoretical approaches range from two simple models, one based on orbital energies corrected by core valence interaction and one based on the equivalent core approximation, to a systematic series of quantum chemical electronic structure methods of increasing sophistication. The two simple models are found to provide a fast orbital interpretation of the spectra, in particular in the low energy parts, while the coverage of the full spectrum is best fulfilled by correlated models. CASPT2 is the most sophisticated model applied, but considering precision as well as computational costs, the single and double excitation configuration interaction model seems to provide the best option to analyze core-valence double hole spectra.

  14. Electron-Poor Polar Intermetallics: Complex Structures, Novel Clusters, and Intriguing Bonding with Pronounced Electron Delocalization.

    Science.gov (United States)

    Lin, Qisheng; Miller, Gordon J

    2018-01-16

    Intermetallic compounds represent an extensive pool of candidates for energy related applications stemming from magnetic, electric, optic, caloric, and catalytic properties. The discovery of novel intermetallic compounds can enhance understanding of the chemical principles that govern structural stability and chemical bonding as well as finding new applications. Valence electron-poor polar intermetallics with valence electron concentrations (VECs) between 2.0 and 3.0 e - /atom show a plethora of unprecedented and fascinating structural motifs and bonding features. Therefore, establishing simple structure-bonding-property relationships is especially challenging for this compound class because commonly accepted valence electron counting rules are inappropriate. During our efforts to find quasicrystals and crystalline approximants by valence electron tuning near 2.0 e - /atom, we observed that compositions close to those of quasicrystals are exceptional sources for unprecedented valence electron-poor polar intermetallics, e.g., Ca 4 Au 10 In 3 containing (Au 10 In 3 ) wavy layers, Li 14.7 Mg 36.8 Cu 21.5 Ga 66 adopting a type IV clathrate framework, and Sc 4 Mg x Cu 15-x Ga 7.5 that is incommensurately modulated. In particular, exploratory syntheses of AAu 3 T (A = Ca, Sr, Ba and T = Ge, Sn) phases led to interesting bonding features for Au, such as columns, layers, and lonsdaleite-type tetrahedral frameworks. Overall, the breadth of Au-rich polar intermetallics originates, in part, from significant relativistics effect on the valence electrons of Au, effects which result in greater 6s/5d orbital mixing, a small effective metallic radius, and an enhanced Mulliken electronegativity, all leading to ultimate enhanced binding with nearly all metals including itself. Two other successful strategies to mine electron-poor polar intermetallics include lithiation and "cation-rich" phases. Along these lines, we have studied lithiated Zn-rich compounds in which structural

  15. [Development of electronic clinical device for concentrated measurement of body temperature].

    Science.gov (United States)

    Zhang, Xu; Ouyang, Bin-lin

    2009-11-01

    An kind of device for concentrated measurement of body temperature which takes ATmega16 microcontroller as the core is designed according to the current situation of measuring body temperature in the hospitals of our country. Taking DS18B20 as the transducer, the device uses PTR8000 wireless communication module to realize the communication from multi-point to single-point. Meanwhile photoelectric detection and USB interfaces are added in the design. Clock chip PCF8563, voice chip ISD1820 and LCD screen I JM12864M are used to realize the functions such as timekeeping, playing voice and displaying and so on.

  16. Prediction of electron concentration reductions in re-entry flow fields due to electrophilic liquid and water injection.

    Science.gov (United States)

    Pergament, H. S.; Mikatarian, R. R.; Kurzius, S. C.

    1972-01-01

    Discussion of an analytical model which leads to predictions of reductions in electron concentrations in reentry flow fields due to the injection of electrophilic liquids and water. The processes incorporated into the model are: penetration and breakup of the liquid jet, droplet acceleration and vaporization, expansion of the liquid spray due to droplet vaporization, electrophilic vapor diffusion, heterogeneous and homogeneous charged species recombination kinetics and homogeneous electron attachment kinetics. Spray boundary calculations are shown to be in good agreement with photographic observations of water and Freon E-3 sprays in wind tunnel tests of a scale model RAM C-III flight vehicle. Fixed-bias electrostatic probe data taken during the RAM C-III flight are interpreted in terms of effective jet penetration distances - which are shown to be consistent with calculations using the present model.

  17. Electronic energy migration in solid versus liquid host matrices for concentrated perylenediimide dye solutions.

    Science.gov (United States)

    Colby, Kathryn A; Bardeen, Christopher J

    2011-07-07

    In this paper, we continue our evaluation of Forster-type theories of exciton diffusion in disordered environments. The perylenediimide dye Lumogen Red is used as a donor molecule in two different liquids, CHCl(3) and dimethylformamide, and the energy transfer to the acceptor molecule Rhodamine 700 is measured using time-resolved fluorescence decays. The exciton motion is measured over Lumogen Red concentrations ranging from 1 × 10(-4) to 5 × 10(-2) M, and the results are compared to previous results for exciton diffusion in a solid polymer. Depending on the theoretical approach used to analyze the data, we find that the energy migration in the liquids is a factor of 2-3 faster than in the solid polymer, even after taking molecular translation into account. Measurements for a Lumogen Red concentration of 10 mM in the different host environments yield diffusion constants ranging from 2.2 to 3.1 nm(2)/ns in the liquids, as compared to 1.1-1.2 nm(2)/ns in solid poly(methyl methacrylate) (PMMA). The results in the liquids are in good agreement with theoretical predictions and numerical simulations of previous workers, while the results in solid PMMA are 2-3 times slower. This discrepancy is discussed in the context of the rapid energetic averaging present in the liquid environments but absent in the solid matrix, where unfavorable configurations and low energy trapping sites are frozen in by the static disorder.

  18. Atomic contributions to the valence band photoelectron spectra of metal-free, iron and manganese phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Bidermane, I., E-mail: ieva.bidermane@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden); Institut des Nanosciences de Paris, UPMC Univ. Paris 06, CNRS UMR 7588, F-75005 Paris (France); Brumboiu, I.E. [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden); Totani, R. [Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio, Coppito, I-67010 L’Aquila (Italy); Grazioli, C. [CNR-IOM, Laboratorio TASC, ss. 14 km. 163.5, Basovizza, 34149 Trieste (Italy); Departement of Chemical and Pharmaceutical Sciences, University of Trieste (Italy); Shariati-Nilsson, M.N.; Herper, H.C.; Eriksson, O.; Sanyal, B. [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden); Ressel, B. [University of Nova Gorica, Vipavska Cesta 11c, 5270 Ajdovščina (Slovenia); Simone, M. de [CNR-IOM, Laboratorio TASC, ss. 14 km. 163.5, Basovizza, 34149 Trieste (Italy); Lozzi, L. [Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio, Coppito, I-67010 L’Aquila (Italy); Brena, B.; Puglia, C. [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden)

    2015-11-15

    Highlights: • In detail comparison between the valence band structure of H{sub 2}Pc, FePc and MnPc. • Comparison between the gas phase samples and thin evaporated films on Au (1 1 1). • Detailed analysis of the atomic orbital contributions to the valence band features. • DFT/HSE06 study of the valence band electronic structure of H{sub 2}Pc, FePc and MnPc. - Abstract: The present work reports a photoelectron spectroscopy study of the low-energy region of the valence band of metal-free phthalocyanine (H{sub 2}Pc) compared with those of iron phthalocyanine (FePc) and manganese phthalocyanine (MnPc). We have analysed in detail the atomic orbital composition of the valence band both experimentally, by making use of the variation in photoionization cross-sections with photon energy, and theoretically, by means of density functional theory. The atomic character of the Highest Occupied Molecular Orbital (HOMO), reflected on the outermost valence band binding energy region, is different for MnPc as compared to the other two molecules. The peaks related to the C 2p contributions, result in the HOMO for H{sub 2}Pc and FePc and in the HOMO-1 for MnPc as described by the theoretical predictions, in very good agreement with the experimental results. The DFT simulations, discerning the atomic contribution to the density of states, indicate how the central metal atom interacts with the C and N atoms of the molecule, giving rise to different partial and total density of states for these three Pc molecules.

  19. Unravelling the structure and dynamics of concentrated aqueous proton defects using simulations incorporating both nuclear and electronic quantum effects

    Science.gov (United States)

    Markland, Thomas

    Aqueous proton defects give rise to a range of structural and dynamical environments that vary with concentration. These manifest as a continuum of infra-red and Raman spectral features. However, assigning spectral features to the underlying structures formed in solution and their dynamical interconversion remains an area of significant debate. In this talk I will show how path integral ab initio molecular dynamics simulations, where the electronic structure is computed on the fly using density functional theory and nuclear quantum effects are included explicitly via path integral molecular dynamics, can be used to accurately describe the spectroscopic properties of liquid water and systems with aqueous proton defects. These simulations, which have previously been computationally intractable for such large condensed phase systems, are now possible due to our recent path integral developments. I will discuss how these simulations can be used to elucidate the linear and multidimensional spectroscopy of concentrated acid systems and the dynamics and structures that give rise to them.

  20. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea

    Science.gov (United States)

    Baek, Sung-Ok; Suvarapu, Lakshmi Narayana; Seo, Young-Kyo

    2015-01-01

    This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving

  1. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea

    Directory of Open Access Journals (Sweden)

    Sung-Ok Baek

    2015-08-01

    Full Text Available This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory

  2. Valence determination as a function of doping in $PrBa_{2} Cu_{3} O_{7}$

    CERN Document Server

    Staub, U; Wasserman, S R; Conner, A G O; Kramer, M J; Patterson, B D; Shi, M; Knapp, M P

    2000-01-01

    We present results of X-ray absorption near edge spectra (XANES), neutron powder diffraction, and resonant X-ray diffraction on samples of PrBa/sub 2/Cu/sub 3/O/sub 7- delta / and Pr/sub 1-x/Ca/sub x/Ba /sub 2/Cu/sub 3/O/sub 7/. The data are obtained as a function of the doping levels of oxygen and Ca. There are significant changes in the Pr L/sub 3/ XANES spectra with changes in oxygen or Ca concentrations, indicating that the Pr electronic properties are affected by doping. The resonant X-ray scattering experiments show that the changes observed occur on Pr ions incorporated in the PrBa /sub 2/Cu/sub 3/O/sub 7- delta / structure, and are not the result of changes to a Pr-containing impurity phase. A quantitative model, based on literature precedent, is used to extract Pr valences from the data, although the XANES cannot distinguish between models involving charge transfer and those involving hybridization. The results are compared with data obtained from Pb/sub 2/Sr/sub 2/Pr/sub 1-x/Ca/sub x/Cu/sub 3/O/sub ...

  3. Materials with intermediate valence ; a comparison with transition metals

    Science.gov (United States)

    Mott, N. F.

    A discussion of metallic intermediate valence materials is given, particularly of hybridisation between the 4f and the conduction band δ. If n, 1 - n are the numbers of ions in each of two charge states, the variation of n with temperature is described. Resistivity is ascribed to scattering of the conduction electrons into the 4f band. The mechanism is compared with that in transition metals and their alloys, particularly Pd1-xAg x. The resistivity can be very large, of order of the Ioffe-Regel value 1/3 e2/ħa. It is argued that both here and in metallic alloys, this can only occur with a two-band model. At high temperatures there is some evidence that s-f scattering does not occur. On discute des matériaux métalliques à valence intermédiaire, en particulier de l'hybridation entre la bande 4f et la bande de conduction. Notant n et 1 - n les nombres d'ions dans chacun des deux états de charge, on décrit la variation de n avec la température. Le mécanisme est comparé avec celui des métaux de transition et de leurs alliages, particulièrement Pd1-xAg x. La résistivité peut être très grande, de l'ordre de la valeur de Ioffe-Regel 1/3 e2/ħa. On donne des arguments tendant à prouver que ceci ne peut se produire que dans le cadre d'un modèle à 2 bandes. Il y a des évidences qu'à haute température la diffusion s-f n'a pas lieu.

  4. An introduction to the calculation of valence EELS: quantum mechanical methods for bulk solids.

    Science.gov (United States)

    Keast, V J

    2013-01-01

    The low-loss region of the electron energy-loss spectrum, the valence EELS, provides information about the electronic structure and optical properties of materials. For bulk materials the spectral intensity can be directly connected to the complex dielectric function. Ab initio quantum mechanical calculations have an important role to play in the interpretation of the fine spectral detail and how this can be connected to the material properties. This paper provides an overview of theoretical background to the calculation of valence EELS in bulk solids and gives specific details on how to run such calculations using the WIEN2k code. The comparison of Au and AuAl(2) illustrates how in metals such calculations are successful in reproducing the main spectral details and can be used to understand the origin of the different colours of these two metals. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Positive valence music restores executive control over sustained attention.

    Science.gov (United States)

    Baldwin, Carryl L; Lewis, Bridget A

    2017-01-01

    Music sometimes improves performance in sustained attention tasks. But the type of music employed in previous investigations has varied considerably, which can account for equivocal results. Progress has been hampered by lack of a systematic database of music varying in key characteristics like tempo and valence. The aims of this study were to establish a database of popular music varying along the dimensions of tempo and valence and to examine the impact of music varying along these dimensions on restoring attentional resources following performance of a sustained attention to response task (SART) vigil. Sixty-nine participants rated popular musical selections that varied in valence and tempo to establish a database of four musical types: fast tempo positive valence, fast tempo negative valence, slow tempo positive valence, and slow tempo negative valence. A second group of 89 participants performed two blocks of the SART task interspersed with either no break or a rest break consisting of 1 of the 4 types of music or silence. Presenting positive valence music (particularly of slow tempo) during an intermission between two successive blocks of the SART significantly decreased miss rates relative to negative valence music or silence. Results support an attentional restoration theory of the impact of music on sustained attention, rather than arousal theory and demonstrate a means of restoring sustained attention. Further, the results establish the validity of a music database that will facilitate further investigations of the impact of music on performance.

  6. Dissociable effects of valence and arousal in adaptive executive control

    National Research Council Canada - National Science Library

    Kuhbandner, Christof; Zehetleitner, Michael

    2011-01-01

    Based on introspectionist, semantic, and psychophysiological experimental frameworks, it has long been assumed that all affective states derive from two independent basic dimensions, valence and arousal...

  7. Effects of phase fraction on superconductivity of low-valence eutectic titanate films

    Science.gov (United States)

    Kurokawa, Hikaru; Yoshimatsu, Kohei; Sakata, Osami; Ohtomo, Akira

    2017-08-01

    Creation and characterization of mixed valence states in transition-metal oxides are a fundamental approach to search for the unprecedented electronic and magnetic properties. In contrast to complex oxides, mixed-valence simple oxides tend to form binary or ternary phases, and turning a valence from one to next must be accompanied by structural transformations owing to a lower tolerance for oxygen non-stoichiometry. In this paper, epitaxial growth and transport properties of low-valence titanate thin films are reported to shed light on recently discovered superconducting γ-phase Ti3O5 (γ-Ti3O5). Single-phase TiO and Ti2O3 films and eutectic films including TiO, Ti2O3, and γ-Ti3O5 phases were independently grown on α-Al2O3 (0001) substrates by using pulsed-laser deposition. The X-ray diffraction measurements revealed clear epitaxial relationships with substrates and among three eutectic phases. Temperature dependence of the resistivity revealed that the γ-Ti3O5-rich films exhibited superconductivity with a maximum of transition temperature (TC) of 6.3 K. Distinct effects of the phase fraction on TC are found between TiO- and Ti2O3-enriched samples, suggesting the complex mechanisms of the superconducting proximity effect.

  8. An electron microscopy based method for the detection and quantification of nanomaterial number concentration in environmentally relevant media

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, A. [School of Geography, Earth and Environmental Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Lead, J.R., E-mail: jlead@mailbox.sc.edu [School of Geography, Earth and Environmental Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Center for Environmental Nanoscience and Risk, Department of Environmental Health Sciences, Arnold School of Public Health, University South Carolina, Columbia 29208, SC (United States); Baalousha, M., E-mail: mbaalous@mailbox.sc.edu [Center for Environmental Nanoscience and Risk, Department of Environmental Health Sciences, Arnold School of Public Health, University South Carolina, Columbia 29208, SC (United States)

    2015-12-15

    Improved detection and characterization of nanomaterials (NMs) in complex environmental media requires the development of novel sampling approaches to improve the detection limit to be close to environmentally realistic concentrations. Transmission electron microscopy (TEM) is an indispensable metrological tool in nanotechnology and environmental nanoscience due to its high spatial resolution and analytical capabilities when coupled to spectroscopic techniques. However, these capabilities are hampered by the conventional sample preparation methods, which suffer from low NM recovery. The current work presents a validated, fully quantitative sampling technique for TEM that overcomes conventional sample preparation shortcomings, and thus enables the use of TEM for measurement of particle number concentration and their detection in complex media at environmentally realistic concentrations. This sampling method is based on ultracentrifugation of NMs from suspension onto a poly-L-lysine (PLL) functionalized TEM grid, using active deposition (by ultracentrifugation) and retention (by PLL interactions with NM surface) of NMs on the substrate, enabling fully quantitative analysis. Similar analysis with AFM was satisfactory in simple media but the lack of chemical-selectivity of AFM limits its applicability for the detection of NMs in complex environmental samples. The sampling approach was validated using both citrate- and PVP-coated AuNMs in pure water, which demonstrated an even distribution of NM on the TEM grid and high NM recovery (80–100%) at environmentally relevant NM concentrations (ca. 0.20–100 μg L{sup −1}). The applicability of the sampling method to complex environmental samples was demonstrated by the quantification of particle number concentration of AuNMs in EPA soft water (with and without Suwannee River fulvic acid) and lake water. This sample preparation approach is also applicable to other types of NMs with some modifications (e.g. centrifugation

  9. Chemical Bonding: The Orthogonal Valence-Bond View

    Directory of Open Access Journals (Sweden)

    Alexander F. Sax

    2015-04-01

    Full Text Available Chemical bonding is the stabilization of a molecular system by charge- and spin-reorganization processes in chemical reactions. These processes are said to be local, because the number of atoms involved is very small. With multi-configurational self-consistent field (MCSCF wave functions, these processes can be calculated, but the local information is hidden by the delocalized molecular orbitals (MO used to construct the wave functions. The transformation of such wave functions into valence bond (VB wave functions, which are based on localized orbitals, reveals the hidden information; this transformation is called a VB reading of MCSCF wave functions. The two-electron VB wave functions describing the Lewis electron pair that connects two atoms are frequently called covalent or neutral, suggesting that these wave functions describe an electronic situation where two electrons are never located at the same atom; such electronic situations and the wave functions describing them are called ionic. When the distance between two atoms decreases, however, every covalent VB wave function composed of non-orthogonal atomic orbitals changes its character from neutral to ionic. However, this change in the character of conventional VB wave functions is hidden by its mathematical form. Orthogonal VB wave functions composed of orthonormalized orbitals never change their character. When localized fragment orbitals are used instead of atomic orbitals, one can decide which local information is revealed and which remains hidden. In this paper, we analyze four chemical reactions by transforming the MCSCF wave functions into orthogonal VB wave functions; we show how the reactions are influenced by changing the atoms involved or by changing their local symmetry. Using orthogonal instead of non-orthogonal orbitals is not just a technical issue; it also changes the interpretation, revealing the properties of wave functions that remain otherwise undetected.

  10. Elastic and inelastic scattering in core and valence emission from solids: Some new directions

    Science.gov (United States)

    Fadley, Charles S.

    1990-12-01

    We review recent work from several groups that has led to some interesting new directions in the study of elastic and inelastic scattering of electrons in both core and valence x-ray photoemission (XPS) and core-initiated Auger emission from solids. The elastic diffraction of core photoelectrons as measured with high angular resolutions of approximately ±1° has been found for the example of c(2×2)S on Ni(001) to provide greater sensitivity to surface atomic structures, including interplanar relaxation in the Ni substrate. Both photoelectron diffraction and Auger electron diffraction have also recently been shown to have the potential for more direct structural determinations via holographic inversions of the data; so far, theoretical simulations have been carried out for c(2×2)S on Ni(001) and inversions of experimental data for Cu(001) and Cu(111) have also yielded encouraging results. The diffraction of inelastically scattered electrons has been found in recent work on Al(001), Ge(111), and W(110) to exhibit similar patterns to those of elastic electrons, but with significant reductions in intensity along low-index directions that can be explained by enhanced multiple scattering effects. The angular dependence of energy-integrated valence-band XPS spectra for Al(001) has furthermore been shown to provide further evidence for hole localization in the final state. This use of such spectra appears to depend on averaging over the entire Brillouin zone due to the effects of phonon-induced non-direct transitions and the analyzer angular acceptance. Finally, such zone-averaged valence spectra for AuCu3(001) have suggested a new method for estimating the atomic orbital makeup or partial densities of states of the initial valence states.

  11. Assessment of nicotine concentration in electronic nicotine delivery system (ENDS) liquids and precision of dosing to aerosol.

    Science.gov (United States)

    Kosmider, Leon; Sobczak, Andrzej; Szołtysek-Bołdys, Izabela; Prokopowicz, Adam; Skórka, Agnieszka; Abdulafeez, Oluyadi; Koszowski, Bartosz

    2015-01-01

    Global use of electronic nicotine delivery systems (ENDS; also called electronic cigarettes, e-cigarettes) has increased dramatically in recent years. However, due to the limited safety studies and growing concerns on the potential toxicity from long term use of ENDS, many national and international governments have employed regulatory measures to curtail its use. One of the most significant challenges regulators of ENDS encounter is the lack of quality standards to assess ENDS, e-liquid (solution used with ENDS which contain nicotine--a highly toxic and addictive substance), and amount of nicotine delivery to aerosol during ENDS use. Aims of the study were to (1) measure and compare nicotine concentration in e-liquids to values reported by manufacturers on packaging labels; (2) assess the precision of nicotine delivery from tank during aerosol formation. Methods: Nine popular Polish e-liquids (based on the market share data from October 2014) were purchased for the study. The labelled nicotine concentration for the selected e-liquids ranged between 11-25 mg/mL. All e-liquids were aerosolized in the laboratory using a smoking simulation machine (Palaczbot). Each e-liquid was aerosolized in a series of 6 consecutive bouts. A single bout consisted of 15 puffs with the following puff topography: 65 mL puff volume, 2.8 sec. puff duration, and 19 sec. interpuff interval. A total of 90 puffs were generated from each e-liquid. Nicotine content in the e-liquids and the aerosol generated were determined by gas chromatography with thermionic sensitive detection (GC-TSD). For seven of nine analyzed e-liquids, the difference between measured and manufacturer labeled nicotine concentration was less than 10%. Nicotine dose in aerosol per bout ranged between 0.77-1.49 mg (equivalent to one-half the nicotine a smoker inhales from a single combustible cigarette). Our analysis showed the high consistency between the labeled and measured nicotine concentration for popular on the

  12. Optical response of two-dimensional few-electron concentric double quantum rings: A local-spin-density-functional theory study

    Science.gov (United States)

    Malet, F.; Pi, M.; Barranco, M.; Lipparini, E.; Serra, Ll.

    2006-11-01

    We have investigated the dipole charge- and spin-density response of few-electron two-dimensional concentric nanorings as a function of the intensity of a perpendicularly applied magnetic field. We show that the dipole response displays signatures associated with the localization of electron states in the inner and outer ring favored by the perpendicularly applied magnetic field. Electron localization produces a more fragmented spectrum due to the appearance of additional edge excitations in the inner and outer ring.

  13. An electron microscopy based method for the detection and quantification of nanomaterial number concentration in environmentally relevant media.

    Science.gov (United States)

    Prasad, A; Lead, J R; Baalousha, M

    2015-12-15

    Improved detection and characterization of nanomaterials (NMs) in complex environmental media requires the development of novel sampling approaches to improve the detection limit to be close to environmentally realistic concentrations. Transmission electron microscopy (TEM) is an indispensable metrological tool in nanotechnology and environmental nanoscience due to its high spatial resolution and analytical capabilities when coupled to spectroscopic techniques. However, these capabilities are hampered by the conventional sample preparation methods, which suffer from low NM recovery. The current work presents a validated, fully quantitative sampling technique for TEM that overcomes conventional sample preparation shortcomings, and thus enables the use of TEM for measurement of particle number concentration and their detection in complex media at environmentally realistic concentrations. This sampling method is based on ultracentrifugation of NMs from suspension onto a poly-l-lysine (PLL) functionalized TEM grid, using active deposition (by ultracentrifugation) and retention (by PLL interactions with NM surface) of NMs on the substrate, enabling fully quantitative analysis. Similar analysis with AFM was satisfactory in simple media but the lack of chemical-selectivity of AFM limits its applicability for the detection of NMs in complex environmental samples. The sampling approach was validated using both citrate- and PVP-coated AuNMs in pure water, which demonstrated an even distribution of NM on the TEM grid and high NM recovery (80-100%) at environmentally relevant NM concentrations (ca. 0.20-100 μg L(-1)). The applicability of the sampling method to complex environmental samples was demonstrated by the quantification of particle number concentration of AuNMs in EPA soft water (with and without Suwannee River fulvic acid) and lake water. This sample preparation approach is also applicable to other types of NMs with some modifications (e.g. centrifugation force and

  14. High-nuclearity mixed-valence clusters and mixed-valence chains: general approach to the calculation of the energy levels and bulk magnetic properties.

    Science.gov (United States)

    Clemente-Juan, J M; Borrás-Almenar, J J; Coronado, E; Palii, A V; Tsukerblat, B S

    2009-05-18

    A general approach to the problem of electron delocalization in the high-nuclearity mixed-valence (MV) clusters containing an arbitrary number of localized spins and itinerant electrons is developed. Along with the double exchange, we consider the isotropic magnetic exchange between the localized electrons as well as the Coulomb intercenter repulsion. As distinguished from the previous approaches dealing with the MV systems in which itinerant electrons are delocalized over all constituent metal sites, here, we consider a more common case of systems exhibiting partial delocalization and containing several delocalized domains. Taking full advantage of the powerful angular momentum technique, we were able to derive closed form analytical expressions for the matrix elements of the full Hamiltonian. These expressions provide an efficient tool for treating complex mixed-valence systems, because they contain only products of 6j-symbols (that appear while treating the delocalized parts) and 9j-symbols (exchange interactions in localized parts) and do not contain high-order recoupling coefficients and 3j-symbols that essentially constrained all previous theories of mixed valency. The approach developed here is accompanied by an efficient computational procedure that allows us to calculate the bulk thermodynamic properties (magnetic susceptibility, magnetization, and magnetic specific heat) of high-nuclearity MV clusters. Finally, this approach has been used to discuss the magnetic properties of the octanuclear MV cluster [Fe(8)(mu(4)-O)(4)(4-Cl-pz)(12)Cl(4)](-) and the diphthalocyanine chains [YPc(2)].CH(2)Cl(2) and [ScPc(2)].CH(2)Cl(2) composed of MV dimers interacting through the magnetic exchange and Coulomb repulsion.

  15. Valence Topological Charge-Transfer Indices for Dipole Moments

    Directory of Open Access Journals (Sweden)

    Francisco Torrens

    2003-01-01

    Full Text Available New valence topological charge-transfer indices are applied to the calculation of dipole moments. The algebraic and vector semisum charge-transfer indices are defined. The combination of the charge-transfer indices allows the estimation of the dipole moments. The model is generalized for molecules with heteroatoms. The ability of the indices for the description of the molecular charge distribution is established by comparing them with the dipole moments of a homologous series of phenyl alcohols. Linear and non-linear correlation models are obtained. The new charge-transfer indices improve the multivariable non-linear regression equations for the dipole moment. When comparing with previous results, the variance decreases 92%. No superposition of the corresponding Gk–Jk and GkV – JkV pairs is observed. This diminishes the risk of co-linearity. Inclusion of the oxygen atom in the p-electron system is beneficial for the description of the dipole moment, owing to either the role of the additional p orbitals provided by the heteroatom or the role of steric factors in the p-electron conjugation. Linear and non-linear correlations between the fractal dimension and various descriptors point not only to a homogeneous molecular structure but also to the ability to predict and tailor drug properties.

  16. Valence XPS structure and chemical bond in Cs2UO2Cl4

    Directory of Open Access Journals (Sweden)

    Teterin Yury A.

    2016-01-01

    Full Text Available Quantitative analysis was done of the valence electrons X-ray photoelectron spectra structure in the binding energy (BE range of 0 eV to ~35 eV for crystalline dicaesium tetrachloro-dioxouranium (VI (Cs2UO2Cl4. This compound contains the uranyl group UO2. The BE and structure of the core electronic shells (~35 eV-1250 eV, as well as the relativistic discrete variation calculation results for the UO2Cl4(D4h cluster reflecting U close environment in Cs2UO2Cl4 were taken into account. The experimental data show that many-body effects due to the presence of cesium and chlorine contribute to the outer valence (0-~15 eV BE spectral structure much less than to the inner valence (~15 eV-~35 eV BE one. The filled U5f electronic states were theoretically calculated and experimentally confirmed to be present in the valence band of Cs2UO2Cl4. It corroborates the suggestion on the direct participation of the U5f electrons in the chemical bond. Electrons of the U6p atomic orbitals participate in formation of both the inner (IVMO and the outer (OVMO valence molecular orbitals (bands. The filled U6p and the O2s, Cl3s electronic shells were found to make the largest contributions to the IVMO formation. The molecular orbitals composition and the sequence order in the binding energy range 0 eV-~35 eV in the UO2Cl4 cluster were established. The experimental and theoretical data allowed a quantitative molecular orbitals scheme for the UO2Cl4 cluster in the BE range 0-~35 eV, which is fundamental for both understanding the chemical bond nature in Cs2UO2Cl4 and the interpretation of other X-ray spectra of Cs2UO2Cl4. The contributions to the chemical binding for the UO2Cl4 cluster were evaluated to be: the OVMO contribution - 76%, and the IVMO contribution - 24 %.

  17. Seniority Number in Valence Bond Theory.

    Science.gov (United States)

    Chen, Zhenhua; Zhou, Chen; Wu, Wei

    2015-09-08

    In this work, a hierarchy of valence bond (VB) methods based on the concept of seniority number, defined as the number of singly occupied orbitals in a determinant or an orbital configuration, is proposed and applied to the studies of the potential energy curves (PECs) of H8, N2, and C2 molecules. It is found that the seniority-based VB expansion converges more rapidly toward the full configuration interaction (FCI) or complete active space self-consistent field (CASSCF) limit and produces more accurate PECs with smaller nonparallelity errors than its molecular orbital (MO) theory-based analogue. Test results reveal that the nonorthogonal orbital-based VB theory provides a reverse but more efficient way to truncate the complete active Hilbert space by seniority numbers.

  18. Icosahedron oligomerization and condensation in intermetallic compounds. Bonding and electronic requirements.

    Science.gov (United States)

    Tillard-Charbonnel, M; Manteghetti, A; Belin, C

    2000-04-17

    Icosahedron-based clustering has been found to be very common in intermetallics, particularly for group 13 and early p-block icosogen elements. Linking of the icosahedral building blocks depends on the valence electron concentrations. Vertex-, edge-, or face-sharing icosahedra occur as the structure compensates for electron deficiency. Some examples of icosahedron-based clusters have been selected for an analysis of the relationships between the structural features (icosahedron oligomerization, atomic defects, etc.) and the bonding and electronic requirements. The extended Hückel method has been used with either a molecular approach or an electronic band structure calculation to rationalize bonding in the intermetallic framework.

  19. Luminescence studies of zinc borates activated with different concentrations of Ce and La under x-ray and electron excitation.

    Science.gov (United States)

    Küçük, N; Ayvacikli, M; Akça, S; Yüksel, M; Guinea, J Garcia; Karabulut, Y; Canimoglu, A; Topaksu, M; Can, N

    2017-09-01

    Several ZnB2O4 powder samples having dopants concentrations of 0.1, 0.01, 0.04wt% Ce and La were prepared using the nitric acid method via the starting oxides. Several complementary methods such as powder X-ray diffraction (XRD), thermal analyses environmental scanning electron microscopy (ESEM), Radioluminescence (RL) and Cathodoluminescence (CL) techniques were used. Unique luminescence properties of Ce doped ZnB2O4 powder samples are reported for the first time. A new luminescence bands appearing in red part of the spectrum and having all the characteristics of Ce(3+) were obtained from RL results. Changing the Ce and La concentration of 0.01-0.1wt% leads to an increase in RL and CL intensities of Ce(3+) and La(3+) ions and also CL emission spectra of ZnB2O4 show gradual shift towards longer wavelength. When we compare the luminescence intensity of the samples it is seen that Ce doped ZnB2O4 has the highest intense whereas La doped ZnB2O4 has the lowest one. However, emission spectra of both Ce and La doped samples kept unchanged. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Prediction of valence and arousal from music features

    NARCIS (Netherlands)

    Den Brinker, A.C.; Van Dinther, C.H.B.A.; Skowronek, J.

    2011-01-01

    Mood is an important attribute of music and knowledge on mood can beused as a basic ingredient in music recommender and retrieval systems. Moods are assumed to be dominantly determined by two dimensions:valence and arousal. An experiment was conducted to attain data forsong-based ratings of valence

  1. Electron-electron correlations in liquid s-p metals

    CERN Document Server

    Leys, F E

    2003-01-01

    We present calculations for the valence electron-electron structure factor in liquid Mg near freezing, assuming knowledge of the jellium result. On the basis of this, we predict significant corrections to jellium short-range correlations in liquid s-p metals and in particular an increase in the electron-electron contact probability.

  2. Valence instabilities as a possible source of actinide system inconsistencies

    Energy Technology Data Exchange (ETDEWEB)

    Sandenaw, T.A.

    1979-08-01

    The presence of a mixed-valence state in light actinides appears evident from the crystal structures of certain U, Np, and Pu phases. As supporting evidence, the physical property response of these actinide elements (and some of their alloys) is compared with that of rare-earth metallic compounds known to have an unstable valence. Impurities may stabilize an intermediate (different) valence state locally in rare-earth compounds in the presence of the valence state of the bulk phase. Impurity elements from different periodic table groupings may likewise stabilize different intermediate valence states in light actinide elements, thus contributing to inconsistencies in results reported by different experimentalists. Any model (theory) advanced for explaining the physical property behavior of U, Np, and Pu may also require consideration of a configurational limit. A phenomenological connection could exist between a martensitic transformation and the fluctuation temperature in both rare earth and actinide systems.

  3. Self-trapped exciton and core-valence luminescence in BaF{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Vistovskyy, V. V., E-mail: vistvv@gmail.com; Zhyshkovych, A. V.; Chornodolskyy, Ya. M.; Voloshinovskii, A. S. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya, 79005 Lviv (Ukraine); Myagkota, O. S. [Lviv Polytechnic National University, 12S. Bandera, 79013 Lviv (Ukraine); Gloskovskii, A. [Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg (Germany); Gektin, A. V. [Institute for Scintillation Materials, NAS of Ukraine 60 Lenina Ave, 61001 Kharkiv (Ukraine); Vasil' ev, A. N. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Rodnyi, P. A. [Saint-Petersburg State Polytechnical University, 29, Polytekhnicheskaya, 195251 Saint-Petersburg (Russian Federation)

    2013-11-21

    The influence of the BaF{sub 2} nanoparticle size on the intensity of the self-trapped exciton luminescence and the radiative core-valence transitions is studied by the luminescence spectroscopy methods using synchrotron radiation. The decrease of the self-trapped exciton emission intensity at energies of exciting photons in the range of optical exciton creation (hν ≤ E{sub g}) is less sensitive to the reduction of the nanoparticle sizes than in the case of band-to-band excitation, where excitons are formed by the recombination way. The intensity of the core-valence luminescence shows considerably weaker dependence on the nanoparticle sizes in comparison with the intensity of self-trapped exciton luminescence. The revealed regularities are explained by considering the relationship between nanoparticle size and photoelectron or photohole thermalization length as well as the size of electronic excitations.

  4. VALENCY AND SYNTACTICAL RELATION IN BIMANESS

    Directory of Open Access Journals (Sweden)

    Made Sri Satyawati

    2012-11-01

    Full Text Available This study presents the findings and descriptions of the replies to severalproblems that have not been completely and deeply discussed in the researchespreviously conducted on Bimanese. The problems are related to micro-linguistic factors,namely valency and syntactical relation in Bimanese. Both deductive and inductiveapproaches were applied to obtain satisfactory results. The main theory employed in thisstudy is Role and Reference Grammar Theory (RRG by Van Valin and J. Lapolla. It wasemployed to completely analyze the collected data in accordance with the problemsproposed in this research, and the inductive approach was employed to analyze the datain order to get novelties.In this study, clause structure is given the first priority to discuss, followed by thediscussion on operator, voice markers, nominalizers, and definiteness. Based on thepredicate category, the clause in Bimanese can be constructed with the constituents thatare under the categories of verb, noun, adjective, number, and adverb (prepositionalphrase. Based on the clause analysis, it has been found that in Bimanese there are severaloperators, each of which has different functional boundary in marking the clausemeaning. One operator may only sign nucleus, core (nucleus and argument, or core andperiphery. Bimanese has also been identified to have four linguistic states expressed byverbs that are made to make sense based on state (Aktisontrat, achievement, andaccomplishment. RRG classifies verbs into ten instead of four. However, in this study, tomake the analysis easier, verbs are classified into four. The predicate in Bimanese can beboth serial verbs and secondary verbs. It has also been found that the mechanism ofchange in valency is marked by the attachment of markers to the verbs resulting incausativity, applicativity, and resultivity. From those syntactical constructions, thesyntactical relation in Bimanese can be clearly identified. The discussion on syntacticalrelation

  5. Social Annotation Valence: The Impact on Online Informed Consent Beliefs and Behavior.

    Science.gov (United States)

    Balestra, Martina; Shaer, Orit; Okerlund, Johanna; Westendorf, Lauren; Ball, Madeleine; Nov, Oded

    2016-07-20

    Social media, mobile and wearable technology, and connected devices have significantly expanded the opportunities for conducting biomedical research online. Electronic consent to collecting such data, however, poses new challenges when contrasted to traditional consent processes. It reduces the participant-researcher dialogue but provides an opportunity for the consent deliberation process to move from solitary to social settings. In this research, we propose that social annotations, embedded in the consent form, can help prospective participants deliberate on the research and the organization behind it in ways that traditional consent forms cannot. Furthermore, we examine the role of the comments' valence on prospective participants' beliefs and behavior. This study focuses specifically on the influence of annotations' valence on participants' perceptions and behaviors surrounding online consent for biomedical research. We hope to shed light on how social annotation can be incorporated into digitally mediated consent forms responsibly and effectively. In this controlled between-subjects experiment, participants were presented with an online consent form for a personal genomics study that contained social annotations embedded in its margins. Individuals were randomly assigned to view the consent form with positive-, negative-, or mixed-valence comments beside the text of the consent form. We compared participants' perceptions of being informed and having understood the material, their trust in the organization seeking the consent, and their actual consent across conditions. We find that comment valence has a marginally significant main effect on participants' perception of being informed (F2=2.40, P=.07); specifically, participants in the positive condition (mean 4.17, SD 0.94) felt less informed than those in the mixed condition (mean 4.50, SD 0.69, P=.09). Comment valence also had a marginal main effect on the extent to which participants reported trusting the

  6. Emotion and language: Valence and arousal affect word recognition

    Science.gov (United States)

    Brysbaert, Marc; Warriner, Amy Beth

    2014-01-01

    Emotion influences most aspects of cognition and behavior, but emotional factors are conspicuously absent from current models of word recognition. The influence of emotion on word recognition has mostly been reported in prior studies on the automatic vigilance for negative stimuli, but the precise nature of this relationship is unclear. Various models of automatic vigilance have claimed that the effect of valence on response times is categorical, an inverted-U, or interactive with arousal. The present study used a sample of 12,658 words, and included many lexical and semantic control factors, to determine the precise nature of the effects of arousal and valence on word recognition. Converging empirical patterns observed in word-level and trial-level data from lexical decision and naming indicate that valence and arousal exert independent monotonic effects: Negative words are recognized more slowly than positive words, and arousing words are recognized more slowly than calming words. Valence explained about 2% of the variance in word recognition latencies, whereas the effect of arousal was smaller. Valence and arousal do not interact, but both interact with word frequency, such that valence and arousal exert larger effects among low-frequency words than among high-frequency words. These results necessitate a new model of affective word processing whereby the degree of negativity monotonically and independently predicts the speed of responding. This research also demonstrates that incorporating emotional factors, especially valence, improves the performance of models of word recognition. PMID:24490848

  7. Efficiency of different polyacrylic acid concentrations on the smear layer, after ART technique, by Scanning Electron Microscopy (SEM).

    Science.gov (United States)

    Raggio, D P; Sônego, F G; Camargo, L B; Marquezan, M; Imparato, J C

    2010-10-01

    To assess the efficiency of different polyacrylic acid concentrations on the removal of the smear layer after caries removal with hand and rotary instruments in affected dentine of primary teeth. In vitro study. Six exfoliated primary molars with carious lesions were divided into two groups for caries removal: (1) hand instrument or (2) low speed bur. Each tooth was cut into four pieces. One piece assigned as control surface and the other three surfaces were actively treated with either 40% Fuji IXGP Liquid (GC America), or 40% Fuji IXGP Liquid diluted with water, and 25% Ketac Molar(TM) Conditioner (3M-ESPE). Surfaces were prepared for scanning electron microscopy (SEM). All images were submitted to an analysis by an experienced SEM professional, regarding presence or absence of smear layer and dentinal demineralization pattern. Chi-squared test was carried out (5% significance). There was no difference concerning the presence of a smear layer in relation to the method of caries removal, and 40% Fuji IXGP diluted with water causes a higher demineralization when compared with the control group of teeth (p=0.01). Treatments with polyacrylic acid are indicated prior to glass ionomer cement application in primary teeth.

  8. Electron spin resonance study of Er-concentration effect in GaAs;Er,O containing charge carriers

    Energy Technology Data Exchange (ETDEWEB)

    Elmasry, F. [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Okubo, S. [Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Ohta, H., E-mail: hoht@kobe-u.ac.jp [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Fujiwara, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-05-21

    Er-concentration effect in GaAs;Er,O containing charge carriers (n-type, high resistance, p-type) has been studied by X-band Electron spin resonance (ESR) at low temperature (4.7 K < T < 18 K). Observed A, B, and C types of ESR signals were identical to those observed previously in GaAs:Er,O without carrier. The local structure around Er-2O centers is not affected by carriers because similar angular dependence of g-values was observed in both cases (with/without carrier). For temperature dependence, linewidth and lineshape analysis suggested the existence of Er dimers with antiferromagnetic exchange interaction of about 7 K. Moreover, drastic decrease of ESR intensity for C signal in p-type sample was observed and it correlates with the decrease of photoluminescence (PL) intensity. Possible model for the Er-2O trap level in GaAs:Er,O is discussed from the ESR and PL experimental results.

  9. Experimental observation of reduced electronic stopping in photo-excited C-60

    NARCIS (Netherlands)

    Alvarado, F; Hoekstra, R; Morgenstern, R; Schlatholter, T

    2005-01-01

    Electronic stopping experienced by a keV He+ ion interacting with the valence electrons of a single fullerene is the predominant channel for energy deposition in such collisions. Electronic excitation of the fullerene valence electrons, achieved by absorption of several 532 nm photons, is expected

  10. Strong valence fluctuation in the quantum critical heavy fermion superconductor β-YbAlB4: a hard x-ray photoemission study.

    Science.gov (United States)

    Okawa, M; Matsunami, M; Ishizaka, K; Eguchi, R; Taguchi, M; Chainani, A; Takata, Y; Yabashi, M; Tamasaku, K; Nishino, Y; Ishikawa, T; Kuga, K; Horie, N; Nakatsuji, S; Shin, S

    2010-06-18

    Electronic structures of the quantum critical superconductor β-YbAlB4 and its polymorph α-YbAlB4 are investigated by using bulk-sensitive hard x-ray photoemission spectroscopy. From the Yb 3d core level spectra, the values of the Yb valence are estimated to be ∼2.73 and ∼2.75 for α- and β-YbAlB4, respectively, thus providing clear evidence for valence fluctuations. The valence band spectra of these compounds also show Yb2+ peaks at the Fermi level. These observations establish an unambiguous case of a strong mixed valence at quantum criticality for the first time among heavy fermion systems, calling for a novel scheme for a quantum critical model beyond the conventional Doniach picture in β-YbAlB4.

  11. Taboo, emotionally valenced, and emotionally neutral word norms

    National Research Council Canada - National Science Library

    Janschewitz, Kristin

    2008-01-01

    Although taboo words are used to study emotional memory and attention, no easily accessible normative data are available that compare taboo, emotionally valenced, and emotionally neutral words on the same scales...

  12. Conduction Mechanism of Valence Change Resistive Switching Memory: A Survey

    OpenAIRE

    Ee Wah Lim; Razali Ismail

    2015-01-01

    Resistive switching effect in transition metal oxide (TMO) based material is often associated with the valence change mechanism (VCM). Typical modeling of valence change resistive switching memory consists of three closely related phenomena, i.e., conductive filament (CF) geometry evolution, conduction mechanism and temperature dynamic evolution. It is widely agreed that the electrochemical reduction-oxidation (redox) process and oxygen vacancies migration plays an essential role in the CF fo...

  13. Effect of valence nucleons on nuclear binding energy

    Energy Technology Data Exchange (ETDEWEB)

    Angeli, I. (Kossuth Lajos Tudomanyegyetem, Debrecen (HU))

    1991-10-01

    The nucleonic promiscuity factor P = N{sub p}N{sub n}/(N{sub p} + N{sub n}), where N{sub p}(N{sub n}) is the number of valence protons (neutrons) or holes, is shown to be a useful parameter in the description of the mass number dependence of nuclear binding energies. This means that most of the deviation from a smooth mass number dependence is caused by the isoscalar interaction between valence protons and neutrons.

  14. Systematic study on intermolecular valence-band dispersion in molecular crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Yamane, Hiroyuki, E-mail: yamane@ims.ac.jp [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki 444-8585 (Japan); Kosugi, Nobuhiro [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki 444-8585 (Japan)

    2015-10-01

    Highlights: • Intermolecular valence-band dispersion of crystalline films of phthalocyanines. • Intermolecular transfer integral versus lattice constant. • Site-specific intermolecular interaction and resultant valence-band dispersion. • Band narrowing effect induced by elevated temperature. - Abstract: Functionalities of organic semiconductors are governed not only by individual properties of constituent molecules but also by solid-state electronic states near the Fermi level such as frontier molecular orbitals, depending on weak intermolecular interactions in various conformations. The individual molecular property has been widely investigated in detail; on the other hand, the weak intermolecular interaction is difficult to investigate precisely due to the presence of the structural and thermal energy broadenings in organic solids. Here we show quite small but essential intermolecular valence band dispersions and their temperature dependence of sub-0.1-eV scale in crystalline films of metal phthalocyanines (H{sub 2}Pc, ZnPc, CoPc, MnPc, and F{sub 16}ZnPc) by using angle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation. The observed bands show intermolecular and site dependent dispersion widths, phases, and periodicities, for different chemical substitution of terminal groups and central metals in the phthalocyanine molecule. The precise and systematic band-dispersion measurement would be a credible approach toward the comprehensive understanding of intermolecular interactions and resultant charge transport properties as well as their tuning by substituents in organic molecular systems.

  15. Emotional Valence and the Free-Energy Principle

    Science.gov (United States)

    Joffily, Mateus; Coricelli, Giorgio

    2013-01-01

    The free-energy principle has recently been proposed as a unified Bayesian account of perception, learning and action. Despite the inextricable link between emotion and cognition, emotion has not yet been formulated under this framework. A core concept that permeates many perspectives on emotion is valence, which broadly refers to the positive and negative character of emotion or some of its aspects. In the present paper, we propose a definition of emotional valence in terms of the negative rate of change of free-energy over time. If the second time-derivative of free-energy is taken into account, the dynamics of basic forms of emotion such as happiness, unhappiness, hope, fear, disappointment and relief can be explained. In this formulation, an important function of emotional valence turns out to regulate the learning rate of the causes of sensory inputs. When sensations increasingly violate the agent's expectations, valence is negative and increases the learning rate. Conversely, when sensations increasingly fulfil the agent's expectations, valence is positive and decreases the learning rate. This dynamic interaction between emotional valence and learning rate highlights the crucial role played by emotions in biological agents' adaptation to unexpected changes in their world. PMID:23785269

  16. THE EFFECT OF IRRADIATION DOSE AND AMMONIA CONCENTRATION ON THE APPLICATION OF ELECTRON BEAM FOR TREATMENT GASES POLLUTION OF SO2AND NOX

    Directory of Open Access Journals (Sweden)

    Erizal Erizal

    2010-06-01

    Full Text Available The application of electron beam for treatment gases pollution of SO2 and NOx has been studied.  The simulated SO2 and NOx gases stream produced from diesel fuel burning boiler were flown into electron beam chamber. Irradiation was conducted using 1000 keV electron beam machine at the dose up to 8.8 kGy, while   water vapour and the ammonia gas with variation concentration flew into the system during irradiation. The concentrations of the gases change were observed during processes. After evaluation, it was found that by increasing irradiation dose, the concentration of SO2 and NOx gases removal increases.  The efficiency of gases removal may reach 98 % for SO2 and 88 % for NOX at a dose of 8.8 kGy. By increasing ammonia concentration, the efficiency gas removal increases. Besides, by-products from the irradiation yield were sulfate and nitrate salt compound which are possible to be used as a fertilizer.      Keywords: radiation, electron beam, gas pollution, SO2, NOx, ammonia

  17. Character Disposition and Behavior Type: Influences of Valence on Preschool Children's Social Judgments

    Science.gov (United States)

    Jones, Elaine F.; Tobias, Marvin; Pauley, Danielle; Thomson, Nicole Renick; Johnson, Shawana Lewis

    2009-01-01

    The authors studied the influences of valence information on preschool children's (n = 47) moral (good or bad), liking (liked or disliked by a friend), and consequence-of-behavior (reward or punishment) judgments. The authors presented 8 scenarios describing the behavior valence, positive valence (help, share), negative valence (verbal insult,…

  18. Influence of nitrogen-doping concentration on the electronic structure of CuAlO{sub 2} by first-principles studies

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei-wei, E-mail: zmliuwwliu@126.com; Chen, Hong-xia; Liu, Cheng-lin; Wang, Rong

    2017-02-05

    Effect of N doping concentration on the electronic structure of N-doped CuAlO{sub 2} was investigated by density functional theory based on generalized-gradient approximation plus orbital potential. Lattice parameters a and c both increase with increasing N-doping concentration. Formation energies increase with increasing N doping concentration and all N-doped CuAlO{sub 2} were structurally stable. The calculated band gaps for N-doped CuAlO{sub 2} narrowed compared to pure CuAlO{sub 2}, which was attributed to the stronger hybridization between Cu-3d and N-2p states and the downward shift of Cu-3p states in conduction bands. The higher the N-doping concentration is, the narrower the band gap. N-doped CuAlO{sub 2} shows a typical p-type semiconductor. The band structure changed from indirect to direct after N doping which will benefit the application of the CuAlO{sub 2} materials in optoelectronic and electronic devices. - Highlights: • Electronic structures of CuAlO{sub 2} with different N content were investigated. • The higher the N-doping concentration is, the narrower the band gap. • All the CuAlO{sub 2} with different N content were structurally stable. • The N-doped CuAlO{sub 2} shows a typical p-type semiconductor characteristic.

  19. Taboo, emotionally valenced, and emotionally neutral word norms.

    Science.gov (United States)

    Janschewitz, Kristin

    2008-11-01

    Although taboo words are used to study emotional memory and attention, no easily accessible normative data are available that compare taboo, emotionally valenced, and emotionally neutral words on the same scales. Frequency, inappropriateness, valence, arousal, and imageability ratings for taboo, emotionally valenced, and emotionally neutral words were made by 78 native-English-speaking college students from a large metropolitan university. The valenced set comprised both positive and negative words, and the emotionally neutral set comprised category-related and category-unrelated words. To account for influences of demand characteristics and personality factors on the ratings, frequency and inappropriateness measures were decomposed into raters' personal reactions to the words versus raters' perceptions of societal reactions to the words (personal use vs. familiarity and offensiveness vs. tabooness, respectively). Although all word sets were rated higher in familiarity and tabooness than in personal use and offensiveness, these differences were most pronounced for the taboo set. In terms of valence, the taboo set was most similar to the negative set, although it yielded higher arousal ratings than did either valenced set. Imageability for the taboo set was comparable to that of both valenced sets. The ratings of each word are presented for all participants as well as for single-sex groups. The inadequacies of the application of normative data to research that uses emotional words and the conceptualization of taboo words as a coherent category are discussed. Materials associated with this article may be accessed at the Psychonomic Society's Archive of Norms, Stimuli, and Data, www.psychonomic.org/archive.

  20. Valence band structure of the Si(331)-(12 x 1) surface reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, Corsin [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory, Rue A-L Breguet 2, 2000 Neuchatel (Switzerland); Fabian Schwier, Eike; Monney, Claude; Didiot, Clement; Mariotti, Nicolas; Gunnar Garnier, Michael; Aebi, Philipp [Department of Physics and Fribourg Center for Nanomaterials, Universite de Fribourg, Chemin du Musee 3, 1700 Fribourg (Switzerland); Gaal-Nagy, Katalin; Onida, Giovanni, E-mail: corsin.battaglia@epfl.ch [Dipartimento di Fisica and European Theoretical Spectroscopy Facility (ETSF), Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy)

    2011-04-06

    Using angle-resolved photoelectron spectroscopy we investigate the electronic valence band structure of the Si(331)-(12 x 1) surface reconstruction for which we recently proposed a structural model containing silicon pentamers as elementary structural building blocks. We find that this surface, reported to be metallic in a previous study, shows a clear band gap at the Fermi energy, indicating semiconducting behavior. An occupied surface state, presumably containing several spectral components, is found centered at - 0.6 eV exhibiting a flat energy dispersion. These results are confirmed by scanning tunneling spectroscopy and are consistent with recent first-principles calculations for our structural model.

  1. Valence Bond Theory Reveals Hidden Delocalized Diradical Character of Polyenes.

    Science.gov (United States)

    Gu, Junjing; Wu, Wei; Danovich, David; Hoffmann, Roald; Tsuji, Yuta; Shaik, Sason

    2017-07-12

    The nature of the electronic-structure of polyenes, their delocalization features, and potential diradicaloid characters constitute a fundamental problem in chemistry. To address this problem, we used valence bond self-consistent field (VBSCF) calculations and modeling of polyenes, C2nH2n+2 (n = 2-10). The theoretical treatment shows that starting with n = 5, the polyene's wave function is mainly a shifting 1,4-diradicaloid, a character that increases as the chain length increases, while the contribution of the fundamental Lewis structure with alternating double and single bonds (1) decays quite fast and becomes minor relative to the diradicaloid pack. We show how, nevertheless, it is this wave function that predicts that polyenes will still exhibit alternating short/long CC bonds like the fundamental structure 1. Furthermore, despite the decay of the VB contribution of 1, it remains the single structure with the largest weight among all the individual structures. The mixing of all the 1,4-diradicaloid structures into 1 follows perturbation theory rules, with the result that the delocalization energy due to this mixing is additive and behaves as a linear function of the number of the double bonds, ΔEdel = -6.9 × n (kcal mol(-1)). The VB modeling shows that while the conjugation stabilizes structure 1, this stabilization energy is energetically overridden by the Pauli repulsion between two adjacent double bonds. Nevertheless, unsubstituted polyenes remain planar; this observation is addressed. Potential manifestations of the diradicaloid nature of polyenes are discussed, and it is concluded that the diradicaloid character is clearly not a well-defined physical property as in real diradicals. Thus, we went full circle to realize that our philosophical question may not be strictly resolved. The localized/delocalized properties of polyenes seem to define a "chemical duality principle". This duality of molecular wave functions is a ubiquitous beguiling phenomenon.

  2. Eu valence and Fermi-surface development in EuX{sub 2}Si{sub 2} (X = Co, Rh, Ir) systems

    Energy Technology Data Exchange (ETDEWEB)

    Goetze, K. [Hochfeld-Magnetlabor Dresden, Helmholtz-Zentrum Dresden-Rossendorf (Germany); TU Dresden, Institut fuer Festkoerperphysik (Germany); Seiro, S.; Geibel, C.; Rosner, H.; Petzold, V. [MPI for Chemical Physics of Solids (Germany); Polyakov, A.; Wosnitza, J. [Hochfeld-Magnetlabor Dresden, Helmholtz-Zentrum Dresden-Rossendorf (Germany); Sheikin, I. [LNCMI-Grenoble (France); Suslov, A. [National High Magnetic Field Laboratory, Tallahassee (United States)

    2013-07-01

    The valence-fluctuating Eu systems EuX{sub 2}Si{sub 2}, with X being the transition metal Co, Ir, or Rh, show different types of ground states, strongly depending on X. The instability of the Eu 4f shell underlies this phenomenon and leads among other effects to different valence states ranging from Eu{sup 2+} over mixed valence and intermediate valence behavior to Eu{sup 3+}. Investigations on the structure and the magnetic behavior of EuCo{sub 2}Si{sub 2}, EuIr{sub 2}Si{sub 2}, and EuRh{sub 2}Si{sub 2} have revealed their Eu valence. Further experiments on specific heat and resistivity gave insights to magnetic ordering, electronic correlations, and possible valence fluctuations. We report about a systematic de Haas-van Alphen study on the Fermi-surface development of the EuX{sub 2}Si{sub 2} compounds in magnetic fields up to 35 T. High-quality single crystals were available for the first time. We focus on the Fermi-surface topology obtained by angle dependent measurements and discuss a comparison to band-structure calculations.

  3. Social learning modulates the lateralization of emotional valence.

    Science.gov (United States)

    Shamay-Tsoory, Simone G; Lavidor, Michal; Aharon-Peretz, Judith

    2008-08-01

    Although neuropsychological studies of lateralization of emotion have emphasized valence (positive vs. negative) or type (basic vs. complex) dimensions, the interaction between the two dimensions has yet to be elucidated. The purpose of the current study was to test the hypothesis that recognition of basic emotions is processed preferentially by the right prefrontal cortex (PFC), whereas recognition of complex social emotions is processed preferentially by the left PFC. Experiment 1 assessed the ability of healthy controls and patients with right and left PFC lesions to recognize basic and complex emotions. Experiment 2 modeled the patient's data of Experiment 1 on healthy participants under lateralized displays of the emotional stimuli. Both experiments support the Type as well as the Valence Hypotheses. However, our findings indicate that the Valence Hypothesis holds for basic but less so for complex emotions. It is suggested that, since social learning overrules the basic preference of valence in the hemispheres, the processing of complex emotions in the hemispheres is less affected by valence.

  4. Space-valence priming with subliminal and supraliminal words.

    Science.gov (United States)

    Ansorge, Ulrich; Khalid, Shah; König, Peter

    2013-01-01

    To date it is unclear whether (1) awareness-independent non-evaluative semantic processes influence affective semantics and whether (2) awareness-independent affective semantics influence non-evaluative semantic processing. In the current study, we investigated these questions with the help of subliminal (masked) primes and visible targets in a space-valence across-category congruence effect. In line with (1), we found that subliminal space prime words influenced valence classification of supraliminal target words (Experiment 1): classifications were faster with a congruent prime (e.g., the prime "up" before the target "happy") than with an incongruent prime (e.g., the prime "up" before the target "sad"). In contrast to (2), no influence of subliminal valence primes on the classification of supraliminal space targets into up- and down-words was found (Experiment 2). Control conditions showed that standard masked response priming effects were found with both subliminal prime types, and that an across-category congruence effect was also found with supraliminal valence primes and spatial target words. The final Experiment 3 confirmed that the across-category congruence effect indeed reflected priming of target categorization of a relevant meaning category. Together, the data jointly confirmed prediction (1) that awareness-independent non-evaluative semantic priming influences valence judgments.

  5. Space-Valence Priming with Subliminal and Supraliminal Words

    Directory of Open Access Journals (Sweden)

    Ulrich eAnsorge

    2013-02-01

    Full Text Available To date it is unclear whether (1 awareness-independent non-evaluative semantic processes influence affective semantics and whether (2 awareness-independent affective semantics influence non-evaluative semantic processing. In the current study, we investigated these questions with the help of subliminal (masked primes and visible targets in a space-valence across-category congruence effect. In line with (1, we found that subliminal space prime words influenced valence classification of supraliminal target words (Experiment 1: Classifications were faster with a congruent prime (e.g., the prime ‘up’ before the target ‘happy’ than with an incongruent prime (e.g., the prime ‘up’ before the target ‘sad’. In contrast to (2, no influence of subliminal valence primes on the classification of supraliminal space targets into up- and down-words was found (Experiment 2. Control conditions showed that standard masked response-priming effects were found with both subliminal prime types, and that an across-category congruence effect was also found with supraliminal valence primes and spatial target words. The final Experiment 3 confirmed that the across-category congruence effect indeed reflected priming of target categorization of a relevant meaning category. Together, the data jointly confirmed prediction (1 that awareness-independent non-evaluative semantic priming influences valence judgments.

  6. Iron valence state of fine-grained material from the Jupiter family comet 81P/Wild 2 - A coordinated TEM/STEM EDS/STXM study

    Science.gov (United States)

    Stodolna, Julien; Gainsforth, Zack; Leroux, Hugues; Butterworth, Anna L.; Tyliszczak, Tolek; Jacob, Damien; Westphal, Andrew J.

    2013-12-01

    The oxidation state of transition metal elements is an indicator of the environmental conditions during formation and history of extraterrestrial materials. We studied the iron valence state of fine-grained material from a bulbous track extracted from the Stardust cometary collector. It likely originated from primitive material of the comet Wild 2. We used synchrotron-based Scanning Transmission X-ray Microscopy (STXM) to collect Fe L3-XANES spectra at a spatial resolution of about 20 nm. Maps of Fe valence state were combined with the elemental maps recorded by energy dispersive X-ray spectroscopy (EDS) with a transmission electron microscope (TEM), on the same areas and with a comparable electron probe size (5-20 nm). As for most Stardust fine-grained material, the samples are severely damaged by the hypervelocity impact in the aerogel collector blocks. They show of a wide range of oxidation state at a micrometer scale, from Fe metal to Fe3+. This heterogeneity of oxidation state can be due to the extreme conditions of the collection. Two major parameters can favor changes in redox state. The first is the high temperature regime, known to be highly heterogeneous and to have locally reached extreme values (up to 2000 K). The second is the local chemical environment. It may contain elements that could favor a reduction or oxidation reaction within the flash-heated Wild 2 fragments. Comparison of maps by STXM and EDS shows evidence for several correlation trends between element concentrations and the iron valence state. These observations, together with the study of a melted rim of a larger particle, suggest that the redox state was not completely redistributed within the impact melts. These local signatures are compatible with precursors that could have been close to primitive matrix material of chondrites or to chondritic interplanetary dust particles. On average, the fine-grained material from Wild 2 displays a molar fraction (Fe2+oxide + Fe3+oxide)/(total Fe

  7. Conduction Mechanism of Valence Change Resistive Switching Memory: A Survey

    Directory of Open Access Journals (Sweden)

    Ee Wah Lim

    2015-09-01

    Full Text Available Resistive switching effect in transition metal oxide (TMO based material is often associated with the valence change mechanism (VCM. Typical modeling of valence change resistive switching memory consists of three closely related phenomena, i.e., conductive filament (CF geometry evolution, conduction mechanism and temperature dynamic evolution. It is widely agreed that the electrochemical reduction-oxidation (redox process and oxygen vacancies migration plays an essential role in the CF forming and rupture process. However, the conduction mechanism of resistive switching memory varies considerably depending on the material used in the dielectric layer and selection of electrodes. Among the popular observations are the Poole-Frenkel emission, Schottky emission, space-charge-limited conduction (SCLC, trap-assisted tunneling (TAT and hopping conduction. In this article, we will conduct a survey on several published valence change resistive switching memories with a particular interest in the I-V characteristic and the corresponding conduction mechanism.

  8. Processing emotional pictures and words: effects of valence and arousal.

    Science.gov (United States)

    Kensinger, Elizabeth A; Schacter, Daniel L

    2006-06-01

    There is considerable debate regarding the extent to which limbic regions respond differentially to items with different valences (positive or negative) or to different stimulus types (pictures or words). In the present event-related fMRI study, 21 participants viewed words and pictures that were neutral, negative, or positive. Negative and positive items were equated on arousal. The participants rated each item for whether it depicted or described something animate or inanimate or something common or uncommon. For both pictures and words, the amygdala, dorsomedial prefrontal cortex (PFC), and ventromedial PFC responded equally to all high-arousal items, regardless of valence. Laterality effects in the amygdala were based on the stimulus type (word = left, picture = bilateral). Valence effects were most apparent when the individuals processed pictures, and the results revealed a lateral/medial distinction within the PFC: The lateral PFC responded differentially to negative items, whereas the medial PFC was more engaged during the processing of positive pictures.

  9. Strain effects on valence bands of wurtzite ZnO

    Science.gov (United States)

    Qiao, LiPing; Chai, ChangChun; Jin, Zhao; Yang, YinTang; Ma, ZhenYang

    2013-09-01

    Based on the k.p theory of Luttinger-Kohn and Bir-Pikus, analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained. Strain effects on valence band edges and hole effective masses in strained wurtzite ZnO materials are also discussed. In comparison with unstrained ZnO materials, apparent movement of valence band edges such as "light hole band", "heavy hole band" and "crystal splitting band" at Γ point is found in strained wurtzite ZnO materials. Moreover, effective masses of "light hole band", "heavy hole band" and "crystal splitting band" for strained wurtzite ZnO materials as the function of stress are given. The analytical results can provide a theoretical foundation for the understanding of physics of strained ZnO materials and its applications with the framework for an effective mass theory.

  10. Optical oscillator strengths for valence-shell and Br-3d inner-shell excitations of HCl and HBr.

    Science.gov (United States)

    Li, Wen-Bin; Zhu, Lin-Fan; Yuan, Zhen-Sheng; Liu, Xiao-Jing; Xu, Ke-Zun

    2006-10-21

    Absolute optical oscillator strength density spectra for valence-shell excitations of HCl and HBr, as well as for Br-3d inner-shell excitations of HBr, have been determined by high-resolution electron-energy-loss-spectroscopy method in the dipole limit. Absolute optical oscillator strengths for the discrete transitions of HCl and HBr are reported and compared with the previous results determined by the photoabsorption method.

  11. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation

    KAUST Repository

    Minenkov, Yury

    2017-03-07

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (<2 kcal mol-1) for some reactions of Na, Mg, Ca, Sr, Ba and Pb, while for a few reactions of Ca and Ba deviations up to 40 kcal mol-1 have been obtained. Large errors are both due to artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol-1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol-1, indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  12. Particle-Size-Induced Valence Changes in Samarium Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Mason, M. G.; Lee, S. -T.; Apai, G.; Davis, R. F.; Shirley, D. A.; Franciosi, A.; Weaver, J. H.

    1981-09-01

    Samarium clusters exhibit mixed-valence behavior which is sensitive to particle size. XPS and UPS data show samarium to be primarily divalent (4f{sup 6} ) at small particle size. The trivalent state (4f{sup 5} ) becomes progressively more abundant with increasing s1ze, becoming the dominant state for the bulk metal. These results are interpreted using a model in which band narrowing, due to reduced surface coordination, is more dominant than surface tension effects in establishing the valence of small samarium clusters.

  13. Representations of modality-general valence for videos and music derived from fMRI data.

    Science.gov (United States)

    Kim, Jongwan; Shinkareva, Svetlana V; Wedell, Douglas H

    2017-03-01

    This study tested for neural representations of valence that are shared across visual and auditory modalities referred to as modality-general representations. On a given trial participants made either affective or semantic judgments of short silent videos or music samples. For each modality valence was manipulated at three levels, positive, neutral, and negative, while controlling for the level of arousal. Whole-brain crossmodal identification of affect indicated the presence of modality-general valence representations that distinguished 1) positive from negative trials (signed valence) and 2) valenced from non-valenced trials (unsigned valence). These results generalized across the two tasks. Brain regions that were sensitive to valence states in the same way for both modalities were identified by searchlight analysis of fMRI data by comparing the correlation of voxel responses to the same and different valence conditions across the two modalities. These analyses identified seven clusters that distinguished signed valence, unsigned valence or both. Signed valence was represented in the precuneus, unsigned valence in the bilateral medial prefrontal cortex, superior temporal sulcus (STS)/postcentral, and middle frontal gyrus (MFG) and both types were represented in the STS/MFG and thalamus. These results support the idea that modality general valence is represented in a network of several locations throughout the brain. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Revealing correlation of valence state with nanoporous structure in cobalt catalyst nanoparticles by in situ environmental TEM.

    Science.gov (United States)

    Xin, Huolin L; Pach, Elzbieta A; Diaz, Rosa E; Stach, Eric A; Salmeron, Miquel; Zheng, Haimei

    2012-05-22

    Simultaneously probing the electronic structure and morphology of materials at the nanometer or atomic scale while a chemical reaction proceeds is significant for understanding the underlying reaction mechanisms and optimizing a materials design. This is especially important in the study of nanoparticle catalysts, yet such experiments have rarely been achieved. Utilizing an environmental transmission electron microscope equipped with a differentially pumped gas cell, we are able to conduct nanoscopic imaging and electron energy loss spectroscopy in situ for cobalt catalysts under reaction conditions. Studies reveal quantitative correlation of the cobalt valence states with the particles' nanoporous structures. The in situ experiments were performed on nanoporous cobalt particles coated with silica, while a 15 mTorr hydrogen environment was maintained at various temperatures (300-600 °C). When the nanoporous particles were reduced, the valence state changed from cobalt oxide to metallic cobalt and concurrent structural coarsening was observed. In situ mapping of the valence state and the corresponding nanoporous structures allows quantitative analysis necessary for understanding and improving the mass activity and lifetime of cobalt-based catalysts, for example, for Fischer-Tropsch synthesis that converts carbon monoxide and hydrogen into fuels, and uncovering the catalyst optimization mechanisms.

  15. Electron donor concentrations in sediments and sediment properties at the agricultural chemicals team research site near New Providence, Iowa, 2006-07

    Science.gov (United States)

    Maharjan, Bijesh; Korom, Scott F.; Smith, Erik A.

    2013-01-01

    The concentrations of electron donors in aquifer sediments are important to the understanding of the fate and transport of redox-sensitive constituents in groundwater, such as nitrate. For a study by the U.S. Geological Survey National Water-Quality Assessment Program, 50 sediment samples were collected from below the water table from 11 boreholes at the U.S. Geological Survey Agricultural Chemicals Team research site near New Providence, Iowa, during 2006-07. All samples were analyzed for gravel, sand (coarse, medium, and fine), silt, clay, Munsell soil color, inorganic carbon content, and for the following electron donors: organic carbon, ferrous iron, and inorganic sulfide. A subset of 14 sediment samples also was analyzed for organic sulfur, but all of these samples had concentrations less than the method detection limit; therefore, the presence of this potential electron donor was not considered further. X-ray diffraction analyses provided important semi-quantitative information of well-crystallized dominant minerals within the sediments that might be contributing electron donors.

  16. Quantitative first-principles calculations of valence and core excitation spectra of solid C60

    Science.gov (United States)

    Fossard, F.; Hug, G.; Gilmore, K.; Kas, J. J.; Rehr, J. J.; Vila, F. D.; Shirley, E. L.

    2017-03-01

    We present calculated valence and C 1 s near-edge excitation spectra of solid C60 and experimental results measured with high-resolution electron energy-loss spectroscopy. The near-edge calculations are carried out using three different methods: solution of the Bethe-Salpeter equation (BSE) as implemented in the ocean suite (Obtaining Core Excitations with Ab Initio methods and the NIST BSE solver), the excited-electron core-hole approach, and the constrained-occupancy method using the Stockholm-Berlin core excitation code, StoBe. The three methods give similar results and are in good agreement with experiment, though the BSE results are the most accurate. The BSE formalism is also used to carry out valence level calculations using the NIST BSE solver. Theoretical results include self-energy corrections to the band gap and bandwidths, lifetime-damping effects, and Debye-Waller effects in the core excitation case. A comparison of spectral features to those observed experimentally illustrates the sensitivity of certain features to computational details, such as self-energy corrections to the band structure and core-hole screening.

  17. Time-resolved four-wave-mixing spectroscopy for inner-valence transitions

    CERN Document Server

    Ding, Thomas; Kaldun, Andreas; Blättermann, Alexander; Meyer, Kristina; Stooß, Veit; Rebholz, Marc; Birk, Paul; Hartmann, Maximilian; Brown, Andrew; Van Der Hart, Hugo; Pfeifer, Thomas

    2015-01-01

    Non-collinear four-wave mixing (FWM) techniques at near-infrared (NIR), visible, and ultraviolet frequencies have been widely used to map vibrational and electronic couplings, typically in complex molecules. However, correlations between spatially localized inner-valence transitions among different sites of a molecule in the extreme ultraviolet (XUV) spectral range have not been observed yet. As an experimental step towards this goal we perform time-resolved FWM spectroscopy with femtosecond NIR and attosecond XUV pulses. The first two pulses (XUV-NIR) coincide in time and act as coherent excitation fields, while the third pulse (NIR) acts as a probe. As a first application we show how coupling dynamics between odd- and even-parity inner-valence excited states of neon can be revealed using a two-dimensional spectral representation. Experimentally obtained results are found to be in good agreement with ab initio time-dependent R-matrix calculations providing the full description of multi-electron interactions,...

  18. Valence transition between Eu sup 2 sup + state and Eu sup 3 sup + state in Eu sub x Y sub 1 sub - sub x Pd sub 2 Si sub 2 and Eu sub x La sub 1 sub - sub x Pd sub 2 Si sub 2

    CERN Document Server

    Sakurai, J; Fukuda, S; Mitsuda, A; Isikawa, Y

    2003-01-01

    In EuPd sub 2 Si sub 2 , the valence transition of Eu atoms between the Eu sup 2 sup + state and the Eu sup 3 sup + state takes place when the temperature of the sample changes. In the present study, we prepared Eu sub x Y sub 1 sub - sub x Pd sub 2 Si sub 2 and Eu sub x La sub 1 sub - sub x Pd sub 2 Si sub 2 , in which the Eu atoms of EuPd sub 2 Si sub 2 are systematically substituted by non-magnetic Y or La atoms, and we have measured the magnetic susceptibility chi, the electric resistivity rho and the thermoelectric power S. We found that the temperature of the valence transition of Eu ions is only very weakly dependent on the alloying concentration x of Eu atoms. In addition, the notable structures of the S(T) curves were observed for these samples, which we understand in term of the anomalies of the relaxation time of conduction electrons interacting with the Eu 4f sup 7 virtual bound state. In this respect, the valence transition of Eu ions in this study makes a contrast with the Kondo problems of the ...

  19. Controlling electron transfer from photoexcited quantum dots to Al doped ZnO nanoparticles with varied dopant concentration

    Science.gov (United States)

    Hua, Jie; Wei, Qi; Du, Yuwei; Yuan, Xi; Wang, Jin; Zhao, Jialong; Li, Haibo

    2018-01-01

    The effects of Al doping on the optical properties of ZnO nanoparticles (NPs) were investigated by steady-state and time-resolved photoluminescence (PL) spectroscopy. The doped NPs were prepared by low temperature hydrolysis process. The optical band gap energy of Al-doped ZnO NPs increased from 3.47 to 3.57 eV as Al doping content increased from 0 to 12%. The deep defect states, such as oxygen acceptor and zinc donor induced by Al doping could significantly influence PL spectra and lifetimes of ZnO NPs. In particular, it was found that the Al doping could obviously suppress the electron transfer process from Cu:Zn-In-S quantum dots to the adjacent ZnO NPs. Moreover, the electron transfer rate kET decreased with increasing Al doping content and decreasing temperature.

  20. Measuring the Valence of Nanocrystal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Jonathan Scharle [Columbia Univ., New York, NY (United States)

    2016-11-30

    The goal of this project is to understand and control the interplay between nanocrystal stoichiometry, surface ligand binding and exchange, and the optoelectronic properties of semiconductor nanocrystals in solution and in thin solid films. We pursued three research directions with this goal in mind: 1) We characterized nanocrystal stoichiometry and its influence on the binding of L-type and X-type ligands, including the thermodynamics of binding and the kinetics of ligand exchange. 2) We developed a quantitative understanding of the relationship between surface ligand passivation and photoluminescence quantum yield. 3) We developed methods to replace the organic ligands on the nanocrystal with halide ligands and controllably deposit these nanocrystals into thin films, where electrical measurements were used to investigate the electrical transport and internanocrystal electronic coupling.

  1. Concentration dependence of the dielectric permittivity, structure, and dynamics of aqueous NaCl solutions: comparison between the Drude oscillator and electronic continuum models.

    Science.gov (United States)

    Renou, Richard; Ding, Minxia; Zhu, Haochen; Szymczyk, Anthony; Malfreyt, Patrice; Ghoufi, Aziz

    2014-04-10

    We report molecular dynamics simulations of aqueous sodium chloride solutions at T = 298 K and p = 1 bar in order to investigate the salt concentration dependence of the dielectric permittivity, the structure, and the dynamical properties. Different models were applied up to 7 m salt concentration: the Drude oscillator model with a negative Drude particle (SWM4-NDP), the TIP4P/2005-Reif nonpolarizable model, and an electronic continuum polarizable model (MDEC). Both SWM4-NDP and MDEC polarizable models were able to quantitatively reproduce the concentration dependence of the dielectric permittivity of NaCl aqueous solutions. On the contrary, the nonpolarizable TIP4P/2005 water model failed to quantitatively predict this concentration dependence. In contrast with the SWM4-NDP model, the MDEC model was unable to capture the concentration dependence of the structure and the dynamics of NaCl solutions. The SWM4-NDP model proved to be the most efficient polarizable model to reproduce quantitatively the concentration dependence of the dielectric permittivity, the dynamics, and the structure of NaCl solutions.

  2. Analysis Of Chemical Bonding Using Ab Initio Valence Bond Theory

    NARCIS (Netherlands)

    Engelberts, J.J.

    2017-01-01

    In this thesis, theoretical chemical research is presented in which the Valence Bond (VB) Theory plays a central role. For the last three chapters, the VB method is used, in combination with Magnetically Induced Ring Currents, to analyze the aromaticity of several conjugated molecules. The

  3. Language Civility, Immediacy and Peace Valence among Nigerian ...

    African Journals Online (AJOL)

    In addition, since interactions in the university, as in all human societies, are language driven, the language-based negotiation in the university can produce either harmony or discord. This study, thus, examined students' perception of university lecturers' immediacy and civility as they relate to peace valence of lecturers ...

  4. Emotional Valence and Arousal Effects on Memory and Hemispheric Asymmetries

    Science.gov (United States)

    Mneimne, Malek; Powers, Alice S.; Walton, Kate E.; Kosson, David S.; Fonda, Samantha; Simonetti, Jessica

    2010-01-01

    This study examined predictions based upon the right hemisphere (RH) model, the valence-arousal model, and a recently proposed integrated model (Killgore & Yurgelun-Todd, 2007) of emotion processing by testing immediate recall and recognition memory for positive, negative, and neutral verbal stimuli among 35 right-handed women. Building upon…

  5. "Plug-and-go" strategy to manipulate streptavidin valencies.

    Science.gov (United States)

    Sun, Xun; Montiel, Daniel; Li, Hao; Yang, Haw

    2014-08-20

    The streptavidin-biotin set is one of the most widely utilized conjugation pairs in biotechnological applications. The tetravalent nature of streptavidin and its homologues, however, tends to result in such undesirable complications as cross-linking or ill-defined stoichiometry. Here, we describe a mutagenesis-free strategy to manipulate the valencies of wild-type streptavidin that only requires commercially available reagents. The basic idea is simple: one obtains the desired streptavidin valency by blocking off unwanted binding sites using ancillary biotin ("plug"); this way, the extraordinary fM-biotin-binding affinity is fully retained for the remaining sites in streptavidin. In the present implementation, the ancillary biotin is attached to an auxiliary separation handle, negatively charged DNA or His-tagged protein, via a photochemically or enzymatically cleavable linker. Mixing streptavidin with the ancillary biotin construct produces a distribution of streptavidin valencies. The subsequent chromatographic separation readily isolates the construct of desired streptavidin valency, and the auxiliary handles are easily removed afterward ("go"). We demonstrate how this "plug-and-go" strategy allows a precise control for the compositions of streptavidin-biotin conjugates at the single-molecule level. This low-entry-barrier protocol could further expand the application scope of the streptavidin technology.

  6. Are valence and arousal separable in emotional experience?

    Science.gov (United States)

    Kron, Assaf; Pilkiw, Maryna; Banaei, Jasmin; Goldstein, Ariel; Anderson, Adam Keith

    2015-02-01

    The bipolar valence-arousal model of conscious experience of emotions is prominent in emotion research. In this work, we examine the validity of this model in the context of feelings elicited by visual stimuli. In particular, we examine whether arousal has a unique contribution over bivariate valence (separate measures for pleasure and displeasure) in explaining physiological arousal (electrodermal activity, EDA) and self-reported feelings at the level of item-specific responses across and within individuals. Our results suggest that self-reports of arousal have neither an advantage in predicting EDA nor make a unique contribution when valence is present in the model. Acceptance of the null hypothesis was confirmed with the use of the Bayesian information criterion. Arousal also showed no advantage over valence in predicting global feelings, but demonstrated a small unique component (1.5% to 4% of variance explained). These results have practical implications for both experimental design in the study of emotions and the underlying bases of their conscious experience. PsycINFO Database Record (c) 2015 APA, all rights reserved.

  7. Mn valence state and electrode performance of perovskite-type ...

    Indian Academy of Sciences (India)

    increase in the oxidation state of Mn ions was due to the formation of Mn4+ ions and oxygen vacancies. The addition of Cu ions to LSM systems could lead to enhanced electrode performance for oxygen reduction reactions originating from the change in valence of Mn ions. Keywords. Cu-doped LSM; electrical conductivity; ...

  8. Language Civility, Immediacy and Peace Valence among Nigerian ...

    African Journals Online (AJOL)

    Language Civility, Immediacy and Peace Valence among Nigerian University Academics. Alexander Essien Timothy, Vincent Ugah Uguma. Abstract. The Sustainable Development Goal (SDG) 16 seeks, in part, to “promote peaceful and inclusive societies for sustainable development ….” Since the university is a vital ...

  9. Effective valence as the control parameter of the superconducting ...

    African Journals Online (AJOL)

    In this paper, we have demonstrated that the effective valence of iron can be used as the control parameter to tune the Tc of this family of superconducting materials. This is achieved by postulating that our model of spin fluctuation which has been used to successfully account for the superconductivity in the cuprates in Ref.

  10. Mobile linkers on DNA-coated colloids: valency without patches.

    Science.gov (United States)

    Angioletti-Uberti, Stefano; Varilly, Patrick; Mognetti, Bortolo M; Frenkel, Daan

    2014-09-19

    Colloids coated with single-stranded DNA (ssDNA) can bind selectively to other colloids coated with complementary ssDNA. The fact that DNA-coated colloids (DNACCs) can bind to specific partners opens the prospect of making colloidal "molecules." However, in order to design DNACC-based molecules, we must be able to control the valency of the colloids, i.e., the number of partners to which a given DNACC can bind. One obvious, but not very simple approach is to decorate the colloidal surface with patches of single-stranded DNA that selectively bind those on other colloids. Here we propose a design principle that exploits many-body effects to control the valency of otherwise isotropic colloids. Using a combination of theory and simulation, we show that we can tune the valency of colloids coated with mobile ssDNA, simply by tuning the nonspecific repulsion between the particles. Our simulations show that the resulting effective interactions lead to low-valency colloids self-assembling in peculiar open structures, very different from those observed in DNACCs with immobile DNA linkers.

  11. Voice and Valency in San Luis Potosi Huasteco

    Science.gov (United States)

    Munoz Ledo Yanez, Veronica

    2014-01-01

    This thesis presents an analysis of the system of transitivity, voice and valency alternations in Huasteco of San Luis Potosi (Mayan) within a functional-typological framework. The study is based on spoken discourse and elicited data collected in the municipalities of Aquismon and Tancanhuitz de Santos in the state of San Luis Potosi, Mexico. The…

  12. verbal extensions: valency decreasing extensions in the basà ...

    African Journals Online (AJOL)

    Finance

    of the Basà language, data collected for this work include discourse ... Keywords: Basà language, reciprocal, reflexive, valency decreasing verbal .... a body part.” This definition may be associated with some inadequacies with regards to what reflexive actually means. For example, A may perform an action on B which may.

  13. Resonance and Aromaticity : An Ab Initio Valence Bond Approach

    NARCIS (Netherlands)

    Rashid, Zahid; van Lenthe, Joop H.; Havenith, Remco W. A.

    2012-01-01

    Resonance energy is one of the criteria to measure aromaticity. The effect of the use of different orbital models is investigated in the calculated resonance energies of cyclic conjugated hydrocarbons within the framework of the ab initio Valence Bond Self-Consistent Field (VBSCF) method. The VB

  14. Spin polarization and magnetic dichroism in photoemission from core and valence states in localized magnetic systems .4. Core-hole polarization in resonant photoemission

    NARCIS (Netherlands)

    vanderLaan, G; Thole, BT

    1995-01-01

    A simple theory is presented for core-hole polarization probed by resonant photoemission in a two-steps approximation. After excitation from a core level to the valence shell, the core hole decays into two shallower core holes under emission of an electron. The nonspherical core hole and the final

  15. Orbital momentum profiles and binding energy spectra for the complete valence shell of molecular fluorine

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Y.; Brion, C.E. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemistry; Brunger, M.J.; Zhao, K.; Grisogono, A.M.; Braidwood, S.; Weigold, E. [Flinders Univ. of South Australia, Adelaide, SA (Australia). Electronic Structure of Materials Centre; Chakravorty, S.J.; Davidson, E.R. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry; Sgamellotti, A. [Univ di Perugia (Italy). Dipartimento di Chimica; von Niessen, W. [Technische Univ. Braunschweig (Germany). Inst fuer Physikalische

    1996-01-01

    The first electronic structural study of the complete valence shell binding energy spectrum of molecular fluorine, encompassing both the outer and inner valence regions, is reported. These binding energy spectra as well as the individual orbital momentum profiles have been measured using an energy dispersive multichannel electron momentum spectrometer at a total energy of 1500 eV, with an energy resolution of 1.5 eV and a momentum resolution of 0.1 a.u. The measured binding energy spectra in the energy range of 14-60 eV are compared with the results of ADC(4) many-body Green`s function and also direct-Configuration Interaction (CI) and MRSD-CI calculations. The experimental orbital electron momentum profiles are compared with SCF theoretical profiles calculated using the target Hartree-Fock approximation with a range of basis sets and with Density Functional Theory predictions in the target Kohn-Sham approximation with non-local potentials. The truncated (aug-cc-pv5z) Dunning basis sets were used for the Density Functional Theory calculations which also include some treatment of correlation via the exchange and correlation potentials. Comparisons are also made with the full ion-neutral overlap amplitude calculated with MRSD-CI wave functions. Large, saturated basis sets (199-GTO) were employed for both the high level SCF near Hartree-Fock limit and MRSD-CI calculations to investigate the effects of electron correlation and relaxation. 66 refs., 9 tabs., 9 figs.

  16. Hydrothermally derived water-dispersible mixed valence copper-chitosan nanocomposite as exceptionally potent antimicrobial agent

    Science.gov (United States)

    Basumallick, Srijita; Rajasekaran, Parthiban; Tetard, Laurene; Santra, Swadeshmukul

    2014-10-01

    We report, for the first time, a one-step hydrothermal (HT) process to design and synthesize water-dispersible chitosan nanoparticles loaded with mixed valence copper. Interestingly, this HT copper-chitosan biocompatible composite exhibits exceptionally high antimicrobial properties. A comprehensive characterization of the composite indicates that the hydrothermal process results in the formation of monodispersed nanoparticles with average size of 40 ± 10 nm. FT-IR and Raman spectroscopic studies unveiled that the hydrolysis of the glycoside bonds as the origin of the depolymerization of chitosan. Furthermore, X-Ray Photoelectron Spectroscopy measurements confirmed the presence of mixed valence copper states in the composite, while UV-Vis and FT-IR studies revealed the chemical interaction of copper with the chitosan matrix. Hence, the extensive spectroscopic data provide strong evidence that the chitosan structure was rearranged to capture copper oxide nanoparticles. Finally, HT copper-chitosan composite showed a complete killing effect when tested against both Gram negative ( E. coli) and Gram positive ( S. aureus) bacteria at metallic copper concentration of 100 μg/ml (1.57 mM). At the same concentration, neither pure chitosan nor copper elicited such antimicrobial efficacy. Thus, we show that HT process significantly enhances the synergistic antimicrobial effect of chitosan and copper in addition to increasing the water dispersibility.

  17. Spectroscopic evidence for temperature-dependent convergence of light- and heavy-hole valence bands of PbQ (Q = Te, Se, S)

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.; Malliakas, C. D.; Wijayaratne, K.; Karlapati, V.; Appathurai, N.; Chung, D. Y.; Rosenkranz, S.; Kanatzidis, M. G.; Chatterjee, U.

    2017-01-01

    We have conducted a temperature- dependent angle-resolved photoemission spectroscopy (ARPES) study of the electronic structures of PbTe, PbSe and PbS. Our ARPES data provide direct evidence for the light-hole upper valence bands (UVBs) and hitherto undetected heavy-hole lower valence bands (LVBs) in these materials. An unusual temperature-dependent relative movement between these bands leads to a monotonic decrease in the energy separation between their maxima with increasing temperature, which is known as band convergence and has long been believed to be the driving factor behind extraordinary thermoelectric performances of these compounds at elevated temperatures.

  18. Soil concentrations of polybrominated diphenyl ethers and trace metals from an electronic waste dump site in the Greater Accra Region, Ghana: Implications for human exposure.

    Science.gov (United States)

    Akortia, Eric; Olukunle, Olubiyi I; Daso, Adegbenro P; Okonkwo, Jonathan O

    2017-03-01

    Unregulated electronic waste (e-waste) recycling operations have become a significant environmental issue as well as human health risk in developing countries across the world. The present study evaluated the extent of pollution in Agbogbloshie e-waste recycling site in Accra, Ghana. The concentrations of polybrominated diphenyl ethers (PBDEs) and some selected trace metals were determined using gas chromatography electron impact ionization mass spectrometry and flame atomic absorption spectrophotometry, respectively. The concentrations of ∑ PBDEs ranged from 15.6 to 96.8ngg -1 dry weight, with an overall mean of 54.8ngg -1 dw. BDE-28 was the dominant congener followed by BDE-209 and BDE-47. The order of mean concentrations of the abundant trace metals was Fe>Cu>Pb≫Mn, with a mean range of .531-289mgkg -1 . Geoaccumulation index suggested that the surface soils deteriorated from moderate to high metal pollution, particularly for Cu, Pb and Fe. Of the trace metals analysed, Fe exhibited the highest concentration ranging from 3.97 to 918mgkg -1 . Correlation and principal component analyses suggested possible interactions between PBDEs and the trace metals analysed, while source assessment suggested that PBDEs and trace metals were mostly derived from inputs from the e-waste recycling activities. Average daily dose (ADD) was estimated using concentrations corresponding to 5th percentile, median and 95th percentile. Hazard quotients of 380 and 862 were obtained for adults and children respectively, for Cu and Pb which is a cause for concern especially for local children. Copyright © 2016. Published by Elsevier Inc.

  19. Electron mobility in polarization-doped Al0-0.2GaN with a low concentration near 1017 cm-3

    Science.gov (United States)

    Zhu, Mingda; Qi, Meng; Nomoto, Kazuki; Hu, Zongyang; Song, Bo; Pan, Ming; Gao, Xiang; Jena, Debdeep; Xing, Huili Grace

    2017-05-01

    In this letter, carrier transport in graded AlxGa1-xN with a polarization-induced n-type doping as low as ˜1017 cm-3 is reported. The graded AlxGa1-xN is grown by metal organic chemical vapor deposition on a sapphire substrate, and a uniform n-type doping without any intentional doping is realized by linearly varying the Al composition from 0% to 20% over a thickness of 600 nm. A compensating center concentration of ˜1017 cm-3 was also estimated. A peak mobility of 900 cm2/V.s at room temperature is extracted at an Al composition of ˜7%, which represents the highest mobility achieved in n-Al0.07GaN with a carrier concentration of ˜1017 cm-3. A comparison between experimental data and theoretical models shows that, at this low doping concentration, both dislocation scattering and alloy scattering are significant in limiting electron mobility and that a dislocation density of doping levels in GaN, a critical parameter in the design of novel power electronics taking advantage of polarization doping.

  20. Persistent low-temperature spin dynamics in the mixed-valence iridate Ba3InIr2O9

    Science.gov (United States)

    Dey, Tusharkanti; Majumder, M.; Orain, J. C.; Senyshyn, A.; Prinz-Zwick, M.; Bachus, S.; Tokiwa, Y.; Bert, F.; Khuntia, P.; Büttgen, N.; Tsirlin, A. A.; Gegenwart, P.

    2017-11-01

    Using thermodynamic measurements, neutron diffraction, nuclear magnetic resonance, and muon spin relaxation, we establish putative quantum spin-liquid behavior in Ba3InIr2O9 , where unpaired electrons are localized on mixed-valence Ir2O9 dimers with Ir4.5 + ions. Despite the antiferromagnetic Curie-Weiss temperature on the order of 10 K, neither long-range magnetic order nor spin freezing are observed down to at least 20 mK, such that spins are short-range correlated and dynamic over nearly three decades in temperature. Quadratic power-law behavior of both the spin-lattice relaxation rate and specific heat indicates the gapless nature of the ground state. We envisage that this exotic behavior may be related to an unprecedented combination of the triangular and buckled honeycomb geometries of nearest-neighbor exchange couplings in the mixed-valence setting.

  1. Valenced Cues and Contexts Have Different Effects on Event-Based Prospective Memory

    OpenAIRE

    Peter Graf; Martin Yu

    2015-01-01

    This study examined the separate influence and joint influences on event-based prospective memory task performance due to the valence of cues and the valence of contexts. We manipulated the valence of cues and contexts with pictures from the International Affective Picture System. The participants, undergraduate students, showed higher performance when neutral compared to valenced pictures were used for cueing prospective memory. In addition, neutral pictures were more effective as cues when ...

  2. Approach and withdrawal tendencies during written word processing: effects of task, emotional valence and emotional arousal

    OpenAIRE

    Citron, Francesca M. M.; Abugaber, David; Herbert, Cornelia

    2016-01-01

    The affective dimensions of emotional valence and emotional arousal affect processing of verbal and pictorial stimuli. Traditional emotional theories assume a linear relationship between these dimensions, with valence determining the direction of a behaviour (approach vs. withdrawal) and arousal its intensity or strength. In contrast, according to the valence-arousal conflict theory, both dimensions are interactively related: positive valence and low arousal (PL) are associated with an implic...

  3. AMORPHOUS SILICON ELECTRONIC STRUCTURE MODELING AND BASIC ELECTRO-PHYSICAL PARAMETERS CALCULATION

    Directory of Open Access Journals (Sweden)

    B. A. Golodenko

    2014-01-01

    Full Text Available Summary. The amorphous semiconductor has any unique processing characteristics and it is perspective material for electronic engineering. However, we have not authentic information about they atomic structure and it is essential knot for execution calculation they electronic states and electro physical properties. The author's methods give to us decision such problem. This method allowed to calculation the amorphous silicon modeling cluster atomics Cartesian coordinates, determined spectrum and density its electronic states and calculation the basics electro physical properties of the modeling cluster. At that determined numerical means of the energy gap, energy Fermi, electron concentration inside valence and conduction band for modeling cluster. The find results provides real ability for purposeful control to type and amorphous semiconductor charge carriers concentration and else provides relation between atomic construction and other amorphous substance physical properties, for example, heat capacity, magnetic susceptibility and other thermodynamic sizes.

  4. Uranium concentration by Crustacea: a structural, ultrastructural and microanalytical study by secondary ion emission and electron probe X ray microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Chassard-Bouchaud, C. (Universite Pierre et Marie Curie, Paris (France))

    1982-05-17

    Experimental intoxications were performed on the Crayfish Pontastacus leptodactylus using hydrosoluble uranium nitrate. Investigations demonstrate that Crustacea are able to concentrate both uranium main radioactive isotopes /sup 238/U and /sup 235/U within the cuticle, gill epithelium, midgut gland (=hepatopancreas) and macrophagic hemocytes. The storage occurs within nucleus and lysosomal system where uranium is precipitated in the form of an unsoluble phosphate. The proposed hypothesis for the metal extrusion is the following: residual bodies containing the uranium precipitates are extruded into the extracellular space where they are absorbed by phagocytosis, by the macrophagic hemocytes.

  5. Site-specific electronic structure of bacterial surface protein layers

    Science.gov (United States)

    Vyalikh, D. V.; Kummer, K.; Kade, A.; Blüher, A.; Katzschner, B.; Mertig, M.; Molodtsov, S. L.

    2009-03-01

    We applied resonant photoemission and X-ray absorption spectroscopy for a detailed characterization of the valence electronic structure of the regular two-dimensional bacterial surface protein layer of Bacillus sphaericus NCTC 9602. Using this approach, we detected valence electron emission from specific chemical sites. In particular, it was found that electrons from the π clouds of aromatic systems make large contributions to the highest occupied molecular orbitals.

  6. Spectroscopic study of Cu2 + and Cu + ions in high-transmission glass. Electronic structure and Cu2 + /Cu + concentrations

    Science.gov (United States)

    Gomez, Susana; Urra, Iñigo; Valiente, Rafael; Rodriguez, Fernando

    2010-07-01

    This work investigates the formation of photoluminescence centres in high-transmission glass (HTG) doped with Cu2O and their capability to transform the solar spectrum by absorption/emission via Stokes-shifted PL into a more efficient spectrum for photovoltaic applications. Among the centres formed in HTG, both green photoluminescent Cu + and the non-photoluminescent Cu2 + centres are created but their relative concentration depends on the thermal treatment and the presence of other co-dopants. The measurement of the absorption coefficient α(λ) nearby the HTG optical gap for Cu + bands is accomplished by following the two-thickness method. This procedure allows us to obtain the actual absorption coefficient for the spectrum of each formed centre, from which we obtain the relative concentration of Cu + /Cu2 + as well as their absolute values. The analysis of the spectra provides information on the absorption cross sections, transition energies and bandwidths, the knowledge of which is essential to check the suitability of such centres for photovoltaic applications in solar cells.

  7. Electron doped layered nickelates: Spanning the phase diagram of the cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Botana, Antia S.; Pardo, Victor; Norman, Michael R.

    2017-07-01

    Pr4Ni3O8 is an overdoped analog of hole-doped layered cuprates. Here we show via ab initio calculations that Ce-doped Pr4Ni3O8 (Pr3CeNi3O8) has the same electronic structure as the antiferromagnetic insulating phase of parent cuprates.We find that substantial Ce doping should be thermodynamically stable and that other 4+ cations would yield a similar antiferromagnetic insulating state, arguing this configuration is robust for layered nickelates of low-enough valence. The analogies with cuprates at different d fillings suggest that intermediate Ce-doping concentrations near 1/8 should be an appropriate place to search for superconductivity in these low-valence Ni oxides.

  8. Electronic Structure of Halogen Doped CuCr2Se4

    Energy Technology Data Exchange (ETDEWEB)

    Arenholz, Elke; Liberati, M.; Neulinger, J. R.; Chopdekar, R.V.; Bettinger, J.S.; Arenholz, E.; Butler, W.; Stacy, A.M.; Idzerda, Y.I.; Suzuki, Y.

    2008-09-13

    We have employed element and chemically sensitive X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) in order to address a long standing controversy regarding the electronic and magnetic state of CuCr{sub 2}Se{sub 4} via halogen doping of the Se anion site in CuCr{sub 2}Se{sub 4-x}Y{sub x} (Y=Cl and Br). Long range magnetic order is observed above room temperature for all samples. The Cr L{sub 2,3} XAS spectra show a prevalent 3+ valence for the Cr ions independent of doping concentration and doping agent. The Cu L{sub 2,3} XAS spectra show a combination of 1+ and 2+ valence states for all samples. XMCD spectra indicate the presence of a magnetic moment associated with the Cu ions that is aligned antiparallel to the Cr moment.

  9. Work Valence as a Predictor of Academic Achievement in the Family Context

    Science.gov (United States)

    Porfeli, Erik; Ferrari, Lea; Nota, Laura

    2013-01-01

    This study asserts a theoretical model of academic and work socialization within the family setting. The presumed associations between parents' work valences, children's work valences and valence perceptions, and children's academic interest and achievement are tested. The results suggest that children's perceptions of parents mediate the…

  10. Developmental Reversals in False Memory: Effects of Emotional Valence and Arousal

    Science.gov (United States)

    Brainerd, C. J.; Holliday, R. E.; Reyna, V. F.; Yang, Y.; Toglia, M. P.

    2010-01-01

    Do the emotional valence and arousal of events distort children's memories? Do valence and arousal modulate counterintuitive age increases in false memory? We investigated those questions in children, adolescents, and adults using the Cornell/Cortland Emotion Lists, a word list pool that induces false memories and in which valence and arousal can…

  11. Distinct Brain Systems Underlie the Processing of Valence and Arousal of Affective Pictures

    Science.gov (United States)

    Nielen, M. M. A.; Heslenfeld, D. J.; Heinen, K.; Van Strien, J. W.; Witter, M. P.; Jonker, C.; Veltman, D. J.

    2009-01-01

    Valence and arousal are thought to be the primary dimensions of human emotion. However, the degree to which valence and arousal interact in determining brain responses to emotional pictures is still elusive. This functional MRI study aimed to delineate neural systems responding to valence and arousal, and their interaction. We measured neural…

  12. Magnetic-field-induced valence transition in rare-earth systems

    Indian Academy of Sciences (India)

    loys are induced by pressure, temperature or chemical alloying. The change in the valence state of rare-earth ion is found to be either continuous or discontinuous. One of the com- mon features of all the systems which show valence instabilities is that, in the intermediate valence phase, the system fluctuates between a ...

  13. Valence-Specific Laterality Effects in Vocal Emotion: Interactions with Stimulus Type, Blocking and Sex

    Science.gov (United States)

    Schepman, Astrid; Rodway, Paul; Geddes, Pauline

    2012-01-01

    Valence-specific laterality effects have been frequently obtained in facial emotion perception but not in vocal emotion perception. We report a dichotic listening study further examining whether valence-specific laterality effects generalise to vocal emotions. Based on previous literature, we tested whether valence-specific laterality effects were…

  14. Distinct brain systems underlie the processing of valence and arousal of affective pictures

    NARCIS (Netherlands)

    Nielen, M. M. A.; Heslenfeld, D. J.; Heinen, K.; van Strien, J. W.; Witter, M. P.; Jonker, C.; Veltman, D. J.

    2009-01-01

    Valence and arousal are thought to be the primary dimensions of human emotion. However, the degree to which valence and arousal interact in determining brain responses to emotional pictures is still elusive. This functional MRI study aimed to delineate neural systems responding to valence and

  15. Strong coupling between 4f valence instability and 3d ferromagnetism in Yb(x)Fe4Sb12 studied by resonant x-ray emission spectroscopy.

    Science.gov (United States)

    Yamaoka, Hitoshi; Jarrige, Ignace; Tsujii, Naohito; Lin, Jung-Fu; Ikeno, Tsuyoshi; Isikawa, Yosikazu; Nishimura, Katsuhiko; Higashinaka, Ryuji; Sato, Hideyuki; Hiraoka, Nozomu; Ishii, Hirofumi; Tsuei, Ku-Ding

    2011-10-21

    We have investigated the temperature and pressure dependency of the electronic structure of Yb-filled skutterudites, YbFe(4)Sb(12) and Yb(0.88)Fe(4)Sb(12), using x-ray absorption and emission spectroscopies. An anomalous increase of the Yb valence, which is beyond the conventional Anderson model picture, is found to coincide with the onset of the ferromagnetic order in the x=0.88 sample below 20 K. In contrast, the nearly stoichiometric YbFe(4)Sb(12) is paramagnetic down to 2 K and the Yb valence is independent of temperature. This evidences a close interplay between the magnetic instability of the Fe 3d electrons and valence instability of the Yb 4f electrons. Under pressure, a sudden increase in the valence is found to occur around 13 GPa for YbFe(4)Sb(12) and 17 GPa for Yb(0.88)YbFe(4)Sb(12). © 2011 American Physical Society

  16. The role of the 5f valence orbitals of early actinides in chemical bonding

    Science.gov (United States)

    Vitova, T.; Pidchenko, I.; Fellhauer, D.; Bagus, P. S.; Joly, Y.; Pruessmann, T.; Bahl, S.; Gonzalez-Robles, E.; Rothe, J.; Altmaier, M.; Denecke, M. A.; Geckeis, H.

    2017-07-01

    One of the long standing debates in actinide chemistry is the level of localization and participation of the actinide 5f valence orbitals in covalent bonds across the actinide series. Here we illuminate the role of the 5f valence orbitals of uranium, neptunium and plutonium in chemical bonding using advanced spectroscopies: actinide M4,5 HR-XANES and 3d4f RIXS. Results reveal that the 5f orbitals are active in the chemical bonding for uranium and neptunium, shown by significant variations in the level of their localization evidenced in the spectra. In contrast, the 5f orbitals of plutonium appear localized and surprisingly insensitive to different bonding environments. We envisage that this report of using relative energy differences between the 5fδ/φ and 5fπ*/5fσ* orbitals as a qualitative measure of overlap-driven actinyl bond covalency will spark activity, and extend to numerous applications of RIXS and HR-XANES to gain new insights into the electronic structures of the actinide elements.

  17. Application of R matrix/MQDT method to valence and core excitations in NO

    Energy Technology Data Exchange (ETDEWEB)

    Hiyama, Miyabi; Kosugi, Nobuhiro [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan)

    2006-04-14

    Both valence and core excitations of the NO molecule are studied using the R matrix/multi-channel quantum defect theory (MQDT) approach. In the case of valence excitation, the quantum defects and the coupling constant between p{pi}-Rydberg state and {sup 2}{pi} state of NO were evaluated. The theoretical quantum defects for {sup 2}{sigma}{sup +}, {sup 2}{pi} and {sup 2}{delta} are in good agreement with the experimental values. The theoretical coupling constants not only for B(2{sup 2}{pi}) but also for L(3{sup 2}{pi}) are in good agreement with the experimental values. The same approach with some improvements to calculate the R matrix part is used to study the core excitation of NO. The potential curves above the N 1s ionization threshold of NO were calculated. Five potential energy curves responsible for the resonances around 412-414 eV are found. The peak at 412 eV in the absorption spectra of NO may possibly be assigned to the resonances whose character is {sigma}{sup *} excitation. On the other hand, the peak at 414 eV in the spectra may possibly be assigned to the resonance whose character is a mixture of multi-electron excitations and {sigma}{sup *} excitation.

  18. Investigation of Structural and Electronic Properties of CH3NH3PbI3 Stabilized by Varying Concentrations of Poly(Methyl Methacrylate (PMMA

    Directory of Open Access Journals (Sweden)

    Celline Awino

    2017-08-01

    Full Text Available Studies have shown that perovskites have a high potential of outdoing silicon based solar cells in terms of solar energy conversion, but their rate of degradation is also high. This study reports on improvement on the stability of CH3NH3PbI3 by passivating it with polymethylmethacrylate (PMMA. Structural and electronic properties of CH3NH3PbI3 stabilized by polymethylmethacrylate (PMMA were investigated by varying concentrations of PMMA in the polymer solutions. Stability tests were performed over a period of time using modulated surface photovoltage (SPV spectroscopy, X-ray diffraction (XRD, and photoluminescence (PL measurements. The XRD patterns confirm the tetragonal structure of the deposited CH3NH3PbI3 for every concentration of PMMA. Furthermore, CH3NH3PbI3 coated with 40 mg/mL of PMMA did not show any impurity phase even after storage in air for 43 days. The Tauc gap (ETauc determined on the basis of the in-phase SPV spectra was found in the range from 1.585 to 1.62 eV for the samples stored during initial days, but shifted towards lower energies as the storage time increased. This can be proposed to be due to different chemical reactions between CH3NH3PbI3/PMMA interfaces and air. PL intensity increased with increasing concentration of PMMA except for the perovskite coated with 40 mg/mL of PMMA. PL quenching in the perovskite coated with 40 mg/mL of PMMA can be interpreted as fast electron transfer towards the substrate in the sample. This study shows that, with an optimum concentration of PMMA coating on CH3NH3PbI3, the lifetime and hence stability on electrical and structural behavior of CH3NH3PbI3 is improved.

  19. Role of dislocations and carrier concentration in limiting the electron mobility of InN films grown by plasma assisted molecular beam epitaxy

    Science.gov (United States)

    Tangi, Malleswararao; De, Arpan; Shivaprasad, S. M.

    2018-01-01

    We report the molecular beam epitaxy growth of device quality InN films on GaN epilayer and nano-wall network (NWN) templates deposited on c-sapphire by varying the film thickness up to 1 μm. The careful experiments are directed towards obtaining high mobility InN layers having a low band gap with improved crystal quality. The dislocation density is quantified by using high resolution X-ray diffraction rocking curve broadening values of symmetric and asymmetric reflections, respectively. We observe that the dislocation density of the InN films grown on GaN NWN is less than that of the films grown on the GaN epilayer. This is attributed to the nanoepitaxial lateral overlayer growth (ELOG) process, where the presence of voids at the interface of InN/GaN NWN prevents the propagation of dislocation lines into the InN epilayers, thereby causing less defects in the overgrown InN films. Thus, this new adaptation of the nano-ELOG growth process enables us to prepare InN layers with high electron mobility. The obtained electron mobility of 2121 cm2/Vs for 1 μm thick InN/GaN NWN is comparable with the literature values of similar thickness InN films. Furthermore, in order to understand the reasons that limit electron mobility, the charge neutrality condition is employed to study the variation of electron mobility as a function of dislocation density and carrier concentration. Overall, this study provides a route to attaining improved crystal quality and electronic properties of InN films.

  20. Au-gated SrTiO{sub 3} field-effect transistors with large electron concentration and current modulation

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Amit, E-mail: averma@nd.edu; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Raghavan, Santosh; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106 (United States)

    2014-09-15

    We report the fabrication of low-leakage rectifying Pt and Au Schottky diodes and Au-gated metal-semiconductor field effect transistors (MESFETs) on n-type SrTiO{sub 3} thin films grown by hybrid molecular beam epitaxy. In agreement with previous studies, we find that compared to Pt, Au provides a higher Schottky barrier height with SrTiO{sub 3}. As a result of the large dielectric constant of SrTiO{sub 3} and the large Schottky barrier height of Au, the Au-gated MESFETs are able to modulate ∼1.6 × 10{sup 14 }cm{sup −2} electron density, the highest modulation yet achieved using metal gates in any material system. These MESFETs modulate current densities up to ∼68 mA/mm, ∼20× times larger than the best demonstrated SrTiO{sub 3} MESFETs. We also discuss the roles of the interfacial layer, and the field-dependent dielectric constant of SrTiO{sub 3} in increasing the pinch off voltage of the MESFET.

  1. The chemical bond in inorganic chemistry the bond valence model

    CERN Document Server

    Brown, I David

    2016-01-01

    The bond valence model is a version of the ionic model in which the chemical constraints are expressed in terms of localized chemical bonds formed by the valence charge of the atoms. Theorems derived from the properties of the electrostatic flux predict the rules obeyed by both ionic and covalent bonds. They make quantitative predictions of coordination number, crystal structure, bond lengths and bond angles. Bond stability depends on the matching of the bonding strengths of the atoms, while the conflicting requirements of chemistry and space lead to the structural instabilities responsible for the unusual physical properties displayed by some materials. The model has applications in many fields ranging from mineralogy to molecular biology.

  2. Emotional valence and arousal interact in attentional control.

    Science.gov (United States)

    Jefferies, Lisa N; Smilek, Daniel; Eich, Eric; Enns, James T

    2008-03-01

    A recent study demonstrated that observers' ability to identify targets in a rapid visual sequence was enhanced when they simultaneously listened to happy music. In the study reported here, we examined how the emotion-attention relationship is influenced by changes in both mood valence (negative vs. positive) and arousal (low vs. high). We used a standard induction procedure to generate calm, happy, sad, and anxious moods in participants. Results for an attentional blink task showed no differences in first-target accuracy, but second-target accuracy was highest for participants with low arousal and negative affect (sad), lowest for those with strong arousal and negative affect (anxious), and intermediate for those with positive affect regardless of their arousal (calm, happy). We discuss implications of this valence-arousal interaction for the control of visual attention.

  3. Human Amygdala Tracks a Feature-Based Valence Signal Embedded within the Facial Expression of Surprise.

    Science.gov (United States)

    Kim, M Justin; Mattek, Alison M; Bennett, Randi H; Solomon, Kimberly M; Shin, Jin; Whalen, Paul J

    2017-09-27

    Human amygdala function has been traditionally associated with processing the affective valence (negative vs positive) of an emotionally charged event, especially those that signal fear or threat. However, this account of human amygdala function can be explained by alternative views, which posit that the amygdala might be tuned to either (1) general emotional arousal (activation vs deactivation) or (2) specific emotion categories (fear vs happy). Delineating the pure effects of valence independent of arousal or emotion category is a challenging task, given that these variables naturally covary under many circumstances. To circumvent this issue and test the sensitivity of the human amygdala to valence values specifically, we measured the dimension of valence within the single facial expression category of surprise. Given the inherent valence ambiguity of this category, we show that surprised expression exemplars are attributed valence and arousal values that are uniquely and naturally uncorrelated. We then present fMRI data from both sexes, showing that the amygdala tracks these consensus valence values. Finally, we provide evidence that these valence values are linked to specific visual features of the mouth region, isolating the signal by which the amygdala detects this valence information. SIGNIFICANCE STATEMENT There is an open question as to whether human amygdala function tracks the valence value of cues in the environment, as opposed to either a more general emotional arousal value or a more specific emotion category distinction. Here, we demonstrate the utility of surprised facial expressions because exemplars within this emotion category take on valence values spanning the dimension of bipolar valence (positive to negative) at a consistent level of emotional arousal. Functional neuroimaging data showed that amygdala responses tracked the valence of surprised facial expressions, unconfounded by arousal. Furthermore, a machine learning classifier identified

  4. Continuum-limit scaling of overlap fermions as valence quarks

    Energy Technology Data Exchange (ETDEWEB)

    Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2009-10-15

    We present the results of a mixed action approach, employing dynamical twisted mass fermions in the sea sector and overlap valence fermions, with the aim of testing the continuum limit scaling behaviour of physical quantities, taking the pion decay constant as an example. To render the computations practical, we impose for this purpose a fixed finite volume with lattice size L{approx}1.3 fm. We also briefly review the techniques we have used to deal with overlap fermions. (orig.)

  5. Quantum Phase Transitions around the Staggered Valence Bond Solid

    OpenAIRE

    Xu, Cenke; Balents, Leon

    2011-01-01

    Motivated by recent numerical results, we study the quantum phase transitions between Z_2 spin liquid, Neel ordered, and various valence bond solid (VBS) states on the honeycomb and square lattices, with emphasis on the staggered VBS. In contrast to the well-understood columnar VBS order, the staggered VBS is not described by an XY order parameter with Z_N anisotropy close to these quantum phase transitions. Instead, we demonstrate that on the honeycomb lattice, the staggered VBS is more appr...

  6. Effects of musical valence on the cognitive processing of lyrics

    OpenAIRE

    Fiveash, Anna

    2014-01-01

    The effects of music on the brain have been extensively researched, and numerous connections have been found between music and language, music and emotion, and music and cognitive processing. Despite this work, these three research areas have never before been drawn together in a single research paradigm. This is significant as their combination could lead to valuable insights into the effects of musical valence on the cognitive processing of lyrics. Based on the feelings-as-information theor...

  7. Feedback Valence Affects Auditory Perceptual Learning Independently of Feedback Probability

    Science.gov (United States)

    Amitay, Sygal; Moore, David R.; Molloy, Katharine; Halliday, Lorna F.

    2015-01-01

    Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they were doing equally well, while 10% positive or 90% negative feedback informed them they were doing equally badly. In all conditions the feedback was random in relation to the listeners’ responses (because the task was to discriminate three identical tones), yet both the valence (negative vs. positive) and the probability of feedback (10% vs. 90%) affected learning. Feedback that informed listeners they were doing badly resulted in better post-training performance than feedback that informed them they were doing well, independent of valence. In addition, positive feedback during training resulted in better post-training performance than negative feedback, but only positive feedback indicating listeners were doing badly on the task resulted in learning. As we have previously speculated, feedback that better reflected the difficulty of the task was more effective in driving learning than feedback that suggested performance was better than it should have been given perceived task difficulty. But contrary to expectations, positive feedback was more effective than negative feedback in driving learning. Feedback thus had two separable effects on learning: feedback valence affected motivation on a subjectively difficult task, and learning occurred only when feedback probability reflected the subjective difficulty. To optimize learning, training programs need to take into consideration both feedback valence and probability. PMID:25946173

  8. Platelet activation, adhesion, inflammation, and aggregation potential are altered in the presence of electronic cigarette extracts of variable nicotine concentrations.

    Science.gov (United States)

    Hom, Sarah; Chen, Li; Wang, Tony; Ghebrehiwet, Berhane; Yin, Wei; Rubenstein, David A

    2016-11-01

    Tobacco smoke extracts prepared from both mainstream and sidestream smoking have been associated with heightened platelet activation, aggregation, adhesion, and inflammation. Conversely, it has been shown that pure nicotine inhibits similar platelet functions. In this work, we 1) evaluated the effects of e-cigarette extracts on platelet activities and 2) elucidated the differences between the nicotine-dependent and non-nicotine dependent (e.g. fine particulate matter or toxic compounds) effects of tobacco and e-cigarette products on platelet activities. To accomplish these goals, platelets from healthy volunteers (n = 50) were exposed to tobacco smoke extracts, e-cigarette vapor extracts, and pure nicotine and changes in platelet activation, adhesion, aggregation, and inflammation were evaluated, using optical aggregation, flow cytometry, and ELISA methods. Interestingly, the exposure of platelets to e-vapor extracts induced a significant up-regulation in the expression of the pro-inflammatory gC1qR and cC1qR and induced a marked increase in the deposition of C3b as compared with traditional tobacco smoke extracts. Similarly, platelet activation, as measured by a prothrombinase based assay, and platelet aggregation were also significantly enhanced after exposure to e-vapor extracts. Finally, platelet adhesion potential toward fibrinogen, von Willebrand factor, and other platelets was also enhanced after exposure to e-cigarette vapor extracts. In the presence of pure nicotine, platelet functions were observed to be inhibited, which further suggests that other constituents of tobacco smoke and electronic vapor can antagonize platelet functions, however, the presence of nicotine in extracts somewhat perpetuated the platelet functional changes in a dose-dependent manner.

  9. Absence of superconductivity and valence bond order in the Hubbard-Heisenberg model for organic charge-transfer solids.

    Science.gov (United States)

    Gomes, N; Clay, R T; Mazumdar, S

    2013-09-25

    A frustrated, effective ½-filled band Hubbard-Heisenberg model has been proposed for describing the strongly dimerized charge-transfer solid families κ-(ET)2X and Z[Pd(dmit)2]2. In addition to showing unconventional superconductivity, these materials also exhibit antiferromagnetism, candidate spin-liquid phases, and, in the case of Z=EtMe3P, a spin-gapped phase that has sometimes been referred to as a valence bond solid. We show that neither superconductivity nor the valence bond order phase occurs within the Hubbard-Heisenberg model. We suggest that a description based on ¼-filling, that is reached when the carrier concentration per molecule instead of per dimer is considered, thus may be appropriate.

  10. Absence of superconductivity and valence bond order in the Hubbard-Heisenberg model for organic charge-transfer solids

    Science.gov (United States)

    Gomes, N.; Clay, R. T.; Mazumdar, S.

    2013-09-01

    A frustrated, effective \\frac{1}{2}-filled band Hubbard-Heisenberg model has been proposed for describing the strongly dimerized charge-transfer solid families κ-(ET)2X and Z[Pd(dmit)2]2. In addition to showing unconventional superconductivity, these materials also exhibit antiferromagnetism, candidate spin-liquid phases, and, in the case of Z=EtMe3P, a spin-gapped phase that has sometimes been referred to as a valence bond solid. We show that neither superconductivity nor the valence bond order phase occurs within the Hubbard-Heisenberg model. We suggest that a description based on \\frac{1}{4}-filling, that is reached when the carrier concentration per molecule instead of per dimer is considered, thus may be appropriate.

  11. Sketching the pion's valence-quark generalised parton distribution

    Directory of Open Access Journals (Sweden)

    C. Mezrag

    2015-02-01

    Full Text Available In order to learn effectively from measurements of generalised parton distributions (GPDs, it is desirable to compute them using a framework that can potentially connect empirical information with basic features of the Standard Model. We sketch an approach to such computations, based upon a rainbow-ladder (RL truncation of QCD's Dyson–Schwinger equations and exemplified via the pion's valence dressed-quark GPD, Hπv(x,ξ,t. Our analysis focuses primarily on ξ=0, although we also capitalise on the symmetry-preserving nature of the RL truncation by connecting Hπv(x,ξ=±1,t with the pion's valence-quark parton distribution amplitude. We explain that the impulse-approximation used hitherto to define the pion's valence dressed-quark GPD is generally invalid owing to omission of contributions from the gluons which bind dressed-quarks into the pion. A simple correction enables us to identify a practicable improvement to the approximation for Hπv(x,0,t, expressed as the Radon transform of a single amplitude. Therewith we obtain results for Hπv(x,0,t and the associated impact-parameter dependent distribution, qπv(x,|b→⊥|, which provide a qualitatively sound picture of the pion's dressed-quark structure at a hadronic scale. We evolve the distributions to a scale ζ=2 GeV, so as to facilitate comparisons in future with results from experiment or other nonperturbative methods.

  12. Basic features of the pion valence-quark distribution function

    Directory of Open Access Journals (Sweden)

    Lei Chang

    2014-10-01

    Full Text Available The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow–ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables a realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, qπ(x; namely, at a characteristic hadronic scale, qπ(x∼(1−x2 for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.

  13. Large electron concentration modulation using capacitance enhancement in SrTiO{sub 3}/SmTiO{sub 3} Fin-field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Amit, E-mail: averma@cornell.edu; Nomoto, Kazuki [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853 (United States); Hwang, Wan Sik [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Materials Engineering, Korea Aerospace University, Goyang City, Gyeonggi-do 412791 (Korea, Republic of); Raghavan, Santosh; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106 (United States); Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853 (United States); Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2016-05-02

    Solid-state modulation of 2-dimensional electron gases (2DEGs) with extreme (∼3.3 × 10{sup 14 }cm{sup −2}) densities corresponding to 1/2 electron per interface unit cell at complex oxide heterointerfaces (such as SrTiO{sub 3}/GdTiO{sub 3} or SrTiO{sub 3}/SmTiO{sub 3}) is challenging because it requires enormous gate capacitances. One way to achieve large gate capacitances is by geometrical capacitance enhancement in fin structures. In this work, we fabricate both Au-gated planar field effect transistors (FETs) and Fin-FETs with varying fin-widths on 60 nm SrTiO{sub 3}/5 nm SmTiO{sub 3} thin films grown by hybrid molecular beam epitaxy. We find that the FinFETs exhibit higher gate capacitance compared to planar FETs. By scaling down the SrTiO{sub 3}/SmTiO{sub 3} fin widths, we demonstrate further gate capacitance enhancement, almost twice compared to the planar FETs. In the FinFETs with narrowest fin-widths, we demonstrate a record 2DEG electron concentration modulation of ∼2.4 × 10{sup 14 }cm{sup −2}.

  14. A pulsed electron-photon fluorescence diagnostic technique for temperature and specie concentration measurement at points in relatively dense, unseedded air flows

    Science.gov (United States)

    Muntz, E. P.; Kunc, J. A.; Erwin, D. A.

    1987-01-01

    An analysis is presented on the use of the fluorescence stimulated by combined pulsed electron and photon beams for the study of gas flows up to densities equivalent to an altitude of about 20 km (number density of about 3 x 10 to the 18th/cu cm). The electron beam acts as a pump, requiring no seed gas, to provide a localized concentration of ions or excited state neutrals that can be probed by saturation optical pulses. A short pulse (10ns) electron beam can be used by itself to provide effectively quench-free emission up to number densities of around 10 to the 18th/cm, but is is difficult to maintain satisfactory spatial resolution at this high density. The use of a nearly simultaneous strong optical pulse increases the flexibility of the diagnostic technique, permitting use at densities greater than 10 to the 18th/cu cm with good spatial resolution. The use of flash X-ray sources combined with optical probing also appears promising for densities above 10 to the 19th/cu cm.

  15. Valenced cues and contexts have different effects on event-based prospective memory.

    Science.gov (United States)

    Graf, Peter; Yu, Martin

    2015-01-01

    This study examined the separate influence and joint influences on event-based prospective memory task performance due to the valence of cues and the valence of contexts. We manipulated the valence of cues and contexts with pictures from the International Affective Picture System. The participants, undergraduate students, showed higher performance when neutral compared to valenced pictures were used for cueing prospective memory. In addition, neutral pictures were more effective as cues when they occurred in a valenced context than in the context of neutral pictures, but the effectiveness of valenced cues did not vary across contexts that differed in valence. The finding of an interaction between cue and context valence indicates that their respective influence on event-based prospective memory task performance cannot be understood in isolation from each other. Our findings are not consistent with by the prevailing view which holds that the scope of attention is broadened and narrowed, respectively, by positively and negatively valenced stimuli. Instead, our findings are more supportive of the recent proposal that the scope of attention is determined by the motivational intensity associated with valenced stimuli. Consistent with this proposal, we speculate that the motivational intensity associated with different retrieval cues determines the scope of attention, that contexts with different valence values determine participants' task engagement, and that prospective memory task performance is determined jointly by attention scope and task engagement.

  16. Valenced cues and contexts have different effects on event-based prospective memory.

    Directory of Open Access Journals (Sweden)

    Peter Graf

    Full Text Available This study examined the separate influence and joint influences on event-based prospective memory task performance due to the valence of cues and the valence of contexts. We manipulated the valence of cues and contexts with pictures from the International Affective Picture System. The participants, undergraduate students, showed higher performance when neutral compared to valenced pictures were used for cueing prospective memory. In addition, neutral pictures were more effective as cues when they occurred in a valenced context than in the context of neutral pictures, but the effectiveness of valenced cues did not vary across contexts that differed in valence. The finding of an interaction between cue and context valence indicates that their respective influence on event-based prospective memory task performance cannot be understood in isolation from each other. Our findings are not consistent with by the prevailing view which holds that the scope of attention is broadened and narrowed, respectively, by positively and negatively valenced stimuli. Instead, our findings are more supportive of the recent proposal that the scope of attention is determined by the motivational intensity associated with valenced stimuli. Consistent with this proposal, we speculate that the motivational intensity associated with different retrieval cues determines the scope of attention, that contexts with different valence values determine participants' task engagement, and that prospective memory task performance is determined jointly by attention scope and task engagement.

  17. Estimating valence from the sound of a word: Computational, experimental, and cross-linguistic evidence.

    Science.gov (United States)

    Louwerse, Max; Qu, Zhan

    2017-06-01

    It is assumed linguistic symbols must be grounded in perceptual information to attain meaning, because the sound of a word in a language has an arbitrary relation with its referent. This paper demonstrates that a strong arbitrariness claim should be reconsidered. In a computational study, we showed that one phonological feature (nasals in the beginning of a word) predicted negative valence in three European languages (English, Dutch, and German) and positive valence in Chinese. In three experiments, we tested whether participants used this feature in estimating the valence of a word. In Experiment 1, Chinese and Dutch participants rated the valence of written valence-neutral words, with Chinese participants rating the nasal-first neutral-valence words more positive and the Dutch participants rating nasal-first neutral-valence words more negative. In Experiment 2, Chinese (and Dutch) participants rated the valence of Dutch (and Chinese) written valence-neutral words without being able to understand the meaning of these words. The patterns replicated the valence patterns from Experiment 1. When the written words from Experiment 2 were transformed into spoken words, results in Experiment 3 again showed that participants estimated the valence of words on the basis of the sound of the word. The computational study and psycholinguistic experiments indicated that language users can bootstrap meaning from the sound of a word.

  18. Role of valence fluctuations in the superconductivity of Ce122 compounds.

    Science.gov (United States)

    Yamaoka, H; Ikeda, Y; Jarrige, I; Tsujii, N; Zekko, Y; Yamamoto, Y; Mizuki, J; Lin, J-F; Hiraoka, N; Ishii, H; Tsuei, K-D; Kobayashi, T C; Honda, F; Onuki, Y

    2014-08-22

    Pressure dependence of the Ce valence in CeCu(2)Ge(2) has been measured up to 24 GPa at 300 K and to 17 GPa at 18-20 K using x-ray absorption spectroscopy in the partial fluorescence yield. A smooth increase of the Ce valence with pressure is observed across the two superconducting (SC) regions without any noticeable irregularity. The chemical pressure dependence of the Ce valence was also measured in Ce(Cu(1-x)Ni(x))(2)Si(2) at 20 K. A very weak, monotonic increase of the valence with x was observed, without any significant change in the two SC regions. Within experimental uncertainties, our results show no evidence for the valence transition with an abrupt change in the valence state near the SC II region, challenging the valence-fluctuation mediated superconductivity model in these compounds at high pressure and low temperature.

  19. Blood free Radicals Concentration Determined by Electron Paramagnetic Resonance Spectroscopy and Delayed Cerebral Ischemia Occurrence in Patients with Aneurysmal Subarachnoid Hemorrhage.

    Science.gov (United States)

    Ewelina, Grzywna; Krzysztof, Stachura; Marek, Moskala; Krzysztof, Kruczala

    2017-09-25

    Pathophysiology of delayed cerebral ischemia and cerebral vasospasm following aneurysmal subarachnoid hemorrhage is still poorly recognized, however free radicals are postulated as one of the crucial players. This study was designed to scrutinize whether the concentration of free radicals in the peripheral venous blood is related to the occurrence of delayed cerebral ischemia associated with cerebral vasospasm. Twenty-four aneurysmal subarachnoid hemorrhage patients and seven patients with unruptured intracranial aneurysm (control group) have been studied. Free radicals in patients' blood have been detected by the electron paramagnetic resonance (CMH.HCl spin probe, 150 K, ELEXSYS E500 spectrometer) on admission and at least 72 h from disease onset. Delayed cerebral ischemia monitoring was performed by daily neurological follow-up and transcranial color coded Doppler. Delayed cerebral ischemia observed in six aneurysmal subarachnoid hemorrhage patients was accompanied by cerebral vasospasm in all six cases. No statistically significant difference in average free radicals concentration between controls and study subgroups was noticed on admission (p = .3; Kruskal-Wallis test). After 72 h free radicals concentration in delayed cerebral ischemia patients (3.19 ± 1.52 mmol/l) differed significantly from the concentration in aneurysmal subarachnoid hemorrhage patients without delayed cerebral ischemia (0.65 ± 0.37 mmol/l) (p = .012; Mann-Whitney test). These findings are consistent with our assumptions and seem to confirm the role of free radicals in delayed cerebral ischemia development. Preliminary results presented above are promising and we need perform further investigation to establish whether blood free radicals concentration may serve as the biomarker of delayed cerebral ischemia associated with cerebral vasospasm.

  20. Morphology, spatial distribution, and concentration of flame retardants in consumer products and environmental dusts using scanning electron microscopy and Raman micro-spectroscopy.

    Science.gov (United States)

    Wagner, Jeff; Ghosal, Sutapa; Whitehead, Todd; Metayer, Catherine

    2013-09-01

    We characterized flame retardant (FR) morphologies and spatial distributions in 7 consumer products and 7 environmental dusts to determine their implications for transfer mechanisms, human exposure, and the reproducibility of gas chromatography-mass spectrometry (GC-MS) dust measurements. We characterized individual particles using scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS). Samples were screened for the presence of 3 FR constituents (bromine, phosphorous, non-salt chlorine) and 2 metal synergists (antimony and bismuth). Subsequent analyses of select samples by RMS enabled molecular identification of the FR compounds and matrix materials. The consumer products and dust samples possessed FR elemental weight percents of up to 36% and 31%, respectively. We identified 24 FR-containing particles in the dust samples and classified them into 9 types based on morphology and composition. We observed a broad range of morphologies for these FR-containing particles, suggesting FR transfer to dust via multiple mechanisms. We developed an equation to describe the heterogeneity of FR-containing particles in environmental dust samples. The number of individual FR-containing particles expected in a 1-mg dust sample with a FR concentration of 100ppm ranged from 1000 particles. The presence of rare, high-concentration bromine particles was correlated with decabromodiphenyl ether concentrations obtained via GC-MS. When FRs are distributed heterogeneously in highly concentrated dust particles, human exposure to FRs may be characterized by high transient exposures interspersed by periods of low exposure, and GC-MS FR concentrations may exhibit large variability in replicate subsamples. Current limitations of this SEM/EDS technique include potential false negatives for volatile and chlorinated FRs and greater quantitation uncertainty for brominated FR in aluminum-rich matrices. Copyright © 2013 Elsevier Ltd. All rights

  1. A Valence-Bond Nonequilibrium Solvation Model for a Twisting Cyanine Dye

    CERN Document Server

    McConnell, Sean; Olsen, Seth

    2014-01-01

    We study a two-state valence-bond electronic Hamiltonian model of non-equilibrium solvation during the excited-state twisting reaction of monomethine cyanines. These dyes are of interest because of the strong environment-dependent enhancement of their fluorescence quantum yield that results from suppression of competing non-radiative decay via twisted internal charge-transfer (TICT) states. For monomethine cyanines, where the ground state is a superposition of structures with different bond and charge localization, there are two twisting pathways with different charge localization in the excited state. The Hamiltonian designed to be as simple as possible consistent with a few well-enumerated assumptions. It is defined by three parameters and is a function of two $\\pi$-bond twisting angle coordinates and a single solvation coordinate. For parameters corresponding to symmetric monomethines, there are two low-energy twisting channels on the excited-state surface that lead to a manifold of twisted intramolecular ...

  2. Interactions between incentive valence and action information in a cued approach-avoidance task.

    Science.gov (United States)

    Hoofs, Vincent; Carsten, Thomas; Boehler, C Nico; Krebs, Ruth M

    2018-01-10

    Environmental stimuli can provoke specific response tendencies depending on their incentive valence. While some studies report positive-approach and negative-avoidance biases, others find no such mappings. To further illuminate the relationship between incentive valence and action requirement, we combined a cued monetary incentive paradigm with an approach/avoidance joystick task. Incentive type was manipulated between groups: The reward group won money, while the punishment group avoided losing money for correct and fast responses to targets following incentive cues. Depending on their orientations, targets had to be 'approached' or 'avoided'. Importantly, incentive valence (signaled by cue color) was orthogonal to action requirement (target orientation). Moreover, targets could carry valence-associated information or not (target color), which was, however, task-irrelevant. First, we observed that both valence cues (reward/punishment) improved performance compared to neutral cues, independent of the required action (approach/avoid), suggesting that advance valence cues do not necessarily produce specific action biases. Second, task-irrelevant valence associations with targets promoted action biases, with valence-associated targets facilitating approach and impairing avoid responses. Importantly, this approach bias for valence-associated targets was observed in both groups and hence occurred independently of absolute valence ('unsigned'). This rather unexpected finding might be related to the absence of a direct contrast between positive valence and negative valence within groups and the common goal to respond fast and accurately in all incentive trials. Together, our results seem to challenge the notion that monetary incentives trigger 'hard-wired' valence-action biases in that specific design choices seem to modulate the presence and/or direction of valence-action biases.

  3. Ecological effects of soil properties and metal concentrations on the composition and diversity of microbial communities associated with land use patterns in an electronic waste recycling region.

    Science.gov (United States)

    Wu, Wencheng; Dong, Changxun; Wu, Jiahui; Liu, Xiaowen; Wu, Yingxin; Chen, Xianbin; Yu, Shixiao

    2017-12-01

    Soil microbes play vital roles in ecosystem functions, and soil microbial communities may be strongly structured by land use patterns associated with electronic waste (e-waste) recycling activities, which can increase the heavy metal concentration in soils. In this study, a suite of soils from five land use types (paddy field, vegetable field, dry field, forest field, and e-waste recycling site) were collected in Longtang Town, Guangdong Province, South China. Soil physicochemical properties and heavy metal concentrations were measured, and the indigenous microbial assemblages were profiled using 16S rRNA high-throughput sequencing and clone library analyses. The results showed that mercury concentration was positively correlated with both Faith's PD and Chao1 estimates, suggesting that the soil microbial alpha diversity was predominantly regulated by mercury. In addition, redundancy analysis indicated that available phosphorus, soil moisture, and mercury were the three major drivers affecting the microbial assemblages. Overall, the microbial composition was determined primarily by land use patterns, and this study provides a novel insight on the composition and diversity of microbial communities in soils associated with e-waste recycling activities. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Redistribution of valence and conduction band states depending on the method of modification of SiO2 structure.

    Science.gov (United States)

    Konashuk, A S; Filatova, E O

    2017-10-04

    The effect of introducing porosity and the insertion of methyl groups in SiO4 tetrahedra on the distribution of valence and conduction band states of SiO2 was studied using high-resolution near edge X-ray absorption fine structure spectroscopy (NEXAFS) and soft X-ray photoelectron spectroscopy (XPS). Alignment of NEXAFS spectra and valence band XPS spectra in a common energy scale was performed using binding energies of the initial levels obtained by XPS. It was established that the insertion of methyl groups into SiO4 tetrahedra leads to a significant shift of the top of the valence band EV to smaller binding energies due to the reduction of the electronegativity of the nearest surrounding neighbors of the Si atoms, while introducing porosity changes the position of EV only slightly. The position of the bottom of the conduction band is affected by neither the introduction of porosity nor the insertion of methyl groups. The formation of the π*C[double bond, length as m-dash]C state near the Fermi level, caused by the presence of porogen residues in the structure of organosilicate glass (OSG) and responsible for the leakage currents, was revealed. It was found that high level porosity in OSG films induces a significant variation of Si-O-Si valence angles. A number of Si-O dangling bonds were found in the surface layers of por-SiO2, while methyl groups effectively passivated these dangling bonds in OSG films. The obtained results are important for understanding the regularities of electronic structure formation in SiO2-based low-k dielectrics, which is necessary for the reduction of energy dissipated in semiconductor integrated circuits (ICs).

  5. X-ray absorption study of the Fe and Mo valence states in Sr{sub 2}FeMoO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Martins, H.P., E-mail: henrique@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, PR (Brazil); Prado, F. [Departamento de Física, Universidad Nacional del Sur, Av. Leandro N. Alem 1253, 8000 Bahía Blanca (Argentina); Caneiro, A. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, Av. Ezequiel Bustillo 9500, 8400 Bariloche (Argentina); Vicentin, F.C.; Chaves, D.S. [Laboratório Nacional de Luz Síncrotron, CNPEM, Caixa Postal 6192, 13083-970 Campinas, SP (Brazil); Mossanek, R.J.O.; Abbate, M. [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-990 Curitiba, PR (Brazil)

    2015-08-15

    Highlights: • Study of the Fe/Mo valence states in Sr{sub 2}FeMoO{sub 6} using X-ray absorption spectroscopy. • The sample was checked to discard disorder and secondary phases. • The sample was stored carefully and measured promptly to avoid aging effects. • The Fe ions present a fairly ionic Fe{sup 3+} (3d{sup 5}) valence. • The Mo ions are in a more covalent Mo{sup 5+} (4d{sup 1}) state. • Fe ions in a 2+ valence state are not present in the Fe-L{sub 2,3} spectrum. • The O-K spectrum is sensitive to the unoccupied electronic states of the metal ions. - Abstract: We studied the Fe and Mo valence states in Sr{sub 2}FeMoO{sub 6} using X-ray absorption spectroscopy. The experimental results were analyzed using atomic multiplet plus crystal field calculations. The analysis indicates that the Fe ions present a fairly ionic Fe{sup 3+} (3d{sup 5}) valence, and that the Mo ions are in a strongly covalent Mo{sup 5+} (4d{sup 1}) state. The presence of Fe ions in a 2+ valence state can be excluded from the Fe-L{sub 2,3} spectrum. These results can be understood taking into account the relative energy of the d-levels, the relative strength of the M d–O p mixing, and the exchange stabilization of the Fe{sup 3+} ion.

  6. Comparison of the electron work function, hole concentration and exciton diffusion length for P3HT and PT prepared by thermal or acid cleavage

    DEFF Research Database (Denmark)

    Tousek, J.; Touskova, J.; Ludvík, J.

    2016-01-01

    The electron work function, hole concentration and diffusion length were compared for poly(3-hexylthiophene) polymer (P3HT) that is commonly used for construction of solar cells, and two types of native polythiophene (PT) samples which are prospective candidates for this purpose. The polythiophene...... of conjugated polymer materials in solar cells, was measured by a modified surface photovoltage method. The approach allowed us to identify the differences in the material properties related to the processing method. Morphology of the samples determined by AFM was another tool showing these differences....... It is stated that a native polythiophene prepared by treatment with acids is a prospective material for solar cells and shows a similar quality as that produced by a thermal process. © 2015 Elsevier Ltd. All rights reserved....

  7. Correlated electron state in CeCu2Si2 controlled through Si to P substitution

    Science.gov (United States)

    Lai, Y.; Saunders, S. M.; Graf, D.; Gallagher, A.; Chen, K.-W.; Kametani, F.; Besara, T.; Siegrist, T.; Shekhter, A.; Baumbach, R. E.

    2017-08-01

    CeCu2Si2 is an exemplary correlated electron metal that features two domes of unconventional superconductivity in its temperature-pressure phase diagram. The first dome surrounds an antiferromagnetic quantum critical point, whereas the more exotic second dome may span the termination point of a line of f -electron valence transitions. This behavior has received intense interest, but what has been missing are ways to access the high pressure behavior under milder conditions. Here we study Si → P chemical substitution, which compresses the unit cell volume but simultaneously weakens the hybridization between the f - and conduction electron states and encourages complex magnetism. At concentrations that show magnetism, applied pressure suppresses the magnetic ordering temperature and superconductivity is recovered for samples with low disorder. These results reveal that the electronic behavior in this system is controlled by a nontrivial combination of effects from unit cell volume and electronic shell filling. Guided by this topography, we discuss prospects for uncovering a valence fluctuation quantum phase transition in the broader family of Ce-based ThCr2Si2 -type materials through chemical substitution.

  8. 1D valence bond solids in a magnetic field

    Science.gov (United States)

    Iaizzi, Adam; Sandvik, Anders W.

    2015-09-01

    A Valence bond solid (VBS) is a nonmagnetic, long-range ordered state of a quantum spin system where local spin singlets are formed in some regular pattern. We here study the competition between VBS order and a fully polarized ferromagnetic state as function of an external magnetic field in a one-dimensional extended Heisenberg model—the J-Q2 model— using stochastic series expansion (SSE) quantum Monte Carlo simulations with directed loop updates. We discuss the ground state phase diagram.

  9. Treating sub-valence correlation effects in domain based pair natural orbital coupled cluster calculations: an out-of-the-box approach

    KAUST Repository

    Bistoni, Giovanni

    2017-06-12

    The validity of the main approximations used in canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) in standard chemical applications is discussed. In particular, we investigate the dependence of the results on the number of electrons included in the correlation treatment in frozen-core (FC) calculations and on the main threshold governing the accuracy of DLPNO all-electron (AE) calculations. Initially, scalar relativistic orbital energies for the ground state of the atoms from Li to Rn in the periodic table are calculated. An energy criterion is applied for determining the orbitals that can be excluded from the correlation treatment in FC coupled cluster calculations without significant loss of accuracy. The heterolytic dissociation energy (HDE) of a series of metal compounds (LiF, NaF, AlF3, CaF2, CuF, GaF3, YF3, AgF, InF3, HfF4 and AuF) is calculated at the canonical CCSD(T) level, and the dependence of the results on the number of correlated electrons is investigated. Although for many of the studied reactions sub-valence correlation effects contribute significantly to the HDE, the use of an energy criterion permits a conservative definition of the size of the core, allowing FC calculations to be performed in a black-box fashion while retaining chemical accuracy. A comparison of the CCSD and the DLPNO-CCSD methods in describing the core-core, core-valence and valence-valence components of the correlation energy is given. It is found that more conservative thresholds must be used for electron pairs containing at least one core electron in order to achieve high accuracy in AE DLPNO-CCSD calculations relative to FC calculations. With the new settings, the DLPNO-CCSD method reproduces canonical CCSD results in both AE and FC calculations with the same accuracy.

  10. Expertise in video game playing is associated with reduced valence-concordant emotional expressivity.

    Science.gov (United States)

    Weinreich, André; Strobach, Tilo; Schubert, Torsten

    2015-01-01

    In carefully selected groups of video game playing (VGP) experts and nonexperts, we examined valence-concordant emotional expressivity. We measured electromyographic (EMG) activity over the corrugator supercilii muscle while participants viewed pleasant, neutral, and unpleasant pictures. Potential group differences concerning valence-concordant expressivity may arise from differences concerning the participants' emotional reactivity. To control for such differences, we concomitantly measured skin conductance response (SCR) and, in a separate affect misattribution procedure (AMP), valence transfer from the same set of stimuli. Importantly, we found attenuated valence-concordant EMG activity over the corrugator supercilii muscle in VGP experts compared to nonexperts, but no differences were evident concerning SCR or valence transfer in the AMP. The findings suggest that expertise in VGP is particularly associated with reduced valence-concordant emotional expressivity. Copyright © 2014 Society for Psychophysiological Research.

  11. Virtual Distance and Soundstage, and their Impacts on Experienced Emotional Valence

    DEFF Research Database (Denmark)

    Christensen, Justin

    2015-01-01

    Research from animal ethology and affective neuroscience suggest that a listener’s perceived distance from a signal source can alter their experienced emotional valence of the music. Furthermore, appraisal theories of emotion suggest that emotionally valenced responses will diverge according...... to the type of emotion presented. For these exploratory investigations, subjects listen to selected musical excerpts on speakers in combination with a tactile transducer attached to their chair. The listening sessions are recorded on EEG supported by subject feedback responses. My hypothesis is that musical...... stimuli should cause stronger valenced responses in the nearfield than at a distance. Thus, music experienced as being negatively valenced at a distance should be more negatively valenced in nearfield, and music that is experienced as having a positive valence at a distance should be more positively...

  12. An ecological valence theory of human color preference.

    Science.gov (United States)

    Palmer, Stephen E; Schloss, Karen B

    2010-05-11

    Color preference is an important aspect of visual experience, but little is known about why people in general like some colors more than others. Previous research suggested explanations based on biological adaptations [Hurlbert AC, Ling YL (2007) Curr Biol 17:623-625] and color-emotions [Ou L-C, Luo MR, Woodcock A, Wright A (2004) Color Res Appl 29:381-389]. In this article we articulate an ecological valence theory in which color preferences arise from people's average affective responses to color-associated objects. An empirical test provides strong support for this theory: People like colors strongly associated with objects they like (e.g., blues with clear skies and clean water) and dislike colors strongly associated with objects they dislike (e.g., browns with feces and rotten food). Relative to alternative theories, the ecological valence theory both fits the data better (even with fewer free parameters) and provides a more plausible, comprehensive causal explanation of color preferences.

  13. Valence-bond quantum Monte Carlo algorithms defined on trees.

    Science.gov (United States)

    Deschner, Andreas; Sørensen, Erik S

    2014-09-01

    We present a class of algorithms for performing valence-bond quantum Monte Carlo of quantum spin models. Valence-bond quantum Monte Carlo is a projective T=0 Monte Carlo method based on sampling of a set of operator strings that can be viewed as forming a treelike structure. The algorithms presented here utilize the notion of a worm that moves up and down this tree and changes the associated operator string. In quite general terms, we derive a set of equations whose solutions correspond to a whole class of algorithms. As specific examples of this class of algorithms, we focus on two cases. The bouncing worm algorithm, for which updates are always accepted by allowing the worm to bounce up and down the tree, and the driven worm algorithm, where a single parameter controls how far up the tree the worm reaches before turning around. The latter algorithm involves only a single bounce where the worm turns from going up the tree to going down. The presence of the control parameter necessitates the introduction of an acceptance probability for the update.

  14. The effects of colour and valence on news evaluation.

    Science.gov (United States)

    Kaspar, Kai; Grümmer, Melanie; Kießler, Antje; Neuß, Celina; Schröter, Franziska

    2017-12-01

    Research across different fields of psychology has reported effects of colour cues on a variety of cognitive processes. Especially, the colour red has been shown to have striking influences. In the context of media reception, however, colour effects have been widely neglected so far. This study made a first step in this direction by investigating the effects of the colour red (compared with blue and grey) on the way news articles are evaluated. Two types of news were framed by a coloured border while the valence of the news content additionally varied. Based on 369 participants who read and evaluated the news articles online, we observed effects for colour cues and news valence in the absence of an interaction effect, indicating that the colour red induced approach motivation. However, only the contrast between red and grey reached statistical significance, indicating that chromatic and achromatic colours may differ in their perceived visual saliency. Overall, these results provide an important complement to previous studies and have practical implications for media researchers and producers. © 2015 International Union of Psychological Science.

  15. Emotional valence contributes to music-induced analgesia.

    Science.gov (United States)

    Roy, Mathieu; Peretz, Isabelle; Rainville, Pierre

    2008-01-01

    The capacity of music to soothe pain has been used in many traditional forms of medicine. Yet, the mechanisms underlying these effects have not been demonstrated. Here, we examine the possibility that the modulatory effect of music on pain is mediated by the valence (pleasant-unpleasant dimension) of the emotions induced. We report the effects of listening to pleasant and unpleasant music on thermal pain in healthy human volunteers. Eighteen participants evaluated the warmth or pain induced by 40.0, 45.5, 47.0 and 48.5 degrees C thermal stimulations applied to the skin of their forearm while listening to pleasant and unpleasant musical excerpts matched for their high level of arousal (relaxing-stimulating dimension). Compared to a silent control condition, only the pleasant excerpts produced highly significant reductions in both pain intensity and unpleasantness, demonstrating the effect of positive emotions induced by music on pain (Pairwise contrasts with silence: p'semotional valence contributes to music-induced analgesia. These findings call for the integration of music to current methods of pain control.

  16. Visuospatial Asymmetries and Emotional Valence Influence Mental Time Travel.

    Science.gov (United States)

    Thomas, Nicole A; Takarangi, Melanie K T

    2017-11-27

    Spatial information is tightly intertwined with temporal and valence-based information. Namely, "past" is represented on the left, and "future" on the right, along a horizontal mental timeline. Similarly, right is associated with positive, whereas left is negative. We developed a novel task to examine the effects of emotional valence and temporal distance on mental representations of time. We compared positivity biases, where positive events are positioned closer to now, and right hemisphere emotion biases, where negative events are positioned to the left. When the entire life span was used, a positivity bias emerged; positive events were closer to now. When timeline length was reduced, positivity and right hemisphere emotion biases were consistent for past events. In contrast, positive and negative events were equidistant from now in the future condition, suggesting positivity and right hemisphere emotion biases opposed one another, leading events to be positioned at a similar distance. We then reversed the timeline by moving past to the right and future to the left. Positivity biases in the past condition were eliminated, and negative events were placed slightly closer to now in the future condition. We conclude that an underlying left-to-right mental representation of time is necessary for positivity biases to emerge for past events; however, our mental representations of future events are inconsistent with positivity biases. These findings point to an important difference in the way in which we represent the past and the future on our mental timeline. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  17. An ecological valence theory of human color preference

    Science.gov (United States)

    Palmer, Stephen E.; Schloss, Karen B.

    2010-01-01

    Color preference is an important aspect of visual experience, but little is known about why people in general like some colors more than others. Previous research suggested explanations based on biological adaptations [Hurlbert AC, Ling YL (2007) Curr Biol 17:623–625] and color-emotions [Ou L-C, Luo MR, Woodcock A, Wright A (2004) Color Res Appl 29:381–389]. In this article we articulate an ecological valence theory in which color preferences arise from people’s average affective responses to color-associated objects. An empirical test provides strong support for this theory: People like colors strongly associated with objects they like (e.g., blues with clear skies and clean water) and dislike colors strongly associated with objects they dislike (e.g., browns with feces and rotten food). Relative to alternative theories, the ecological valence theory both fits the data better (even with fewer free parameters) and provides a more plausible, comprehensive causal explanation of color preferences. PMID:20421475

  18. In-medium pion valence distributions in a light-front model

    Energy Technology Data Exchange (ETDEWEB)

    Melo, J.P.B.C. de, E-mail: joao.mello@cruzeirodosul.edu.br [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Tsushima, K. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Ahmed, I. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); National Center for Physics, Quaidi-i-Azam University Campus, Islamabad 45320 (Pakistan)

    2017-03-10

    Pion valence distributions in nuclear medium and vacuum are studied in a light-front constituent quark model. The in-medium input for studying the pion properties is calculated by the quark-meson coupling model. We find that the in-medium pion valence distribution, as well as the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant.

  19. Valence and conduction band offsets of β-Ga2O3/AlN heterojunction

    KAUST Repository

    Sun, Haiding

    2017-10-16

    Both β-Ga2O3 and wurtzite AlN have wide bandgaps of 4.5–4.9 and 6.1 eV, respectively. We calculated the in-plane lattice mismatch between the (−201) plane of β-Ga2O3 and the (0002) plane of AlN, which was found to be 2.4%. This is the smallest mismatch between β-Ga2O3 and binary III-nitrides which is beneficial for the formation of a high quality β-Ga2O3/AlN heterojunction. However, the valence and conduction band offsets (VBO and CBO) at the β-Ga2O3/AlN heterojunction have not yet been identified. In this study, a very thin (less than 2 nm) β-Ga2O3 layer was deposited on an AlN/sapphire template to form the heterojunction by pulsed laser deposition. High-resolution X-ray photoelectron spectroscopy revealed the core-level (CL) binding energies of Ga 3d and Al 2p with respect to the valence band maximum in individual β-Ga2O3 and AlN layers, respectively. The separation between Ga 3d and Al 2p CLs at the β-Ga2O3/AlN interface was also measured. Eventually, the VBO was found to be −0.55 ± 0.05 eV. Consequently, a staggered-gap (type II) heterojunction with a CBO of −1.75 ± 0.05 eV was determined. The identification of the band alignment of the β-Ga2O3/AlN heterojunction could facilitate the design of optical and electronic devices based on these and related alloys.

  20. Electronic energy migration on different time scales: concentration dependence of the time-resolved anisotropy and fluorescence quenching of Lumogen Red in poly(methyl methacrylate).

    Science.gov (United States)

    Colby, Kathryn A; Burdett, Jonathan J; Frisbee, Robert F; Zhu, Lingyan; Dillon, Robert J; Bardeen, Christopher J

    2010-03-18

    Electronic energy transfer plays an important role in many types of organic electronic devices. Forster-type theories of exciton diffusion provide a way to calculate diffusion constants and lengths, but their applicability to amorphous polymer systems must be evaluated. In this paper, the perylenediimide dye Lumogen Red in a poly(methyl methacrylate) host matrix is used to test theories of exciton motion over Lumogen Red concentrations (C(LR)'s) ranging from 1 x 10(-4) to 5 x 10(-2) M. Two experimental quantities are measured. First, time-resolved anisotropy decays in films containing only Lumogen Red provide an estimate of the initial energy transfer rate from the photoexcited molecule. Second, the Lumogen Red lifetime decays in mixed systems where the dyes Malachite Green and Rhodamine 700 act as energy acceptors are measured to estimate the diffusive quenching of the exciton. From the anisotropy measurements, it is found that theory accurately predicts both the C(LR)(-2) concentration dependence of the polarization decay time tau(pol), as well as its magnitude to within 30%. The theory also predicts that the diffusive quenching rate is proportional to C(LR)(alpha), where alpha ranges between 1.00 and 1.33. Experimentally, it is found that alpha = 1.1 +/- 0.2 when Malachite Green is used as an acceptor, and alpha = 1.2 +/- 0.2 when Rhodamine 700 is the acceptor. On the basis of the theory that correctly describes the anisotropy data, the exciton diffusion constant is projected to be 4-9 nm(2)/ns. By use of several different analysis methods for the quenching data, the experimental diffusion constant is found to be in the range of 0.32-1.20 nm(2)/ns. Thus the theory successfully describes the early time anisotropy data but fails to quantitatively describe the quenching experiments which are sensitive to motion on longer time scales. The data are consistent with the idea that orientational and energetic disorder leads to a time-dependent exciton migration rate

  1. Band width and multiple-angle valence-state mapping of diamond

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, I.; Terminello, L.J.; Sutherland, D.G.J. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The band width may be considered the single most important parameter characterizing the electronic structure of a solid. The ratio of band width and Coulomb repulsion determines how correlated or delocalized an electron system is. Some of the most interesting solids straddle the boundary between localized and delocalized, e.g. the high-temperature superconductors. The bulk of the band calculations available today is based on local density functional (DF) theory. Even though the Kohn-Sham eigenvalues from that theory do not represent the outcome of a band-mapping experiment, they are remarkably similar to the bands mapped via photoemission. Strictly speaking, one should use an excited state calculation that takes the solid`s many-body screening response to the hole created in photoemission into account. Diamond is a useful prototype semiconductor because of its low atomic number and large band width, which has made it a long-time favorite for testing band theory. Yet, the two experimental values of the band width of diamond have error bars of {+-}1 eV and differ by 3.2 eV. To obtain an accurate valence band width for diamond, the authors use a band-mapping method that collects momentum distributions instead of the usual energy distributions. This method has undergone extensive experimental and theoretical tests in determining the band width of lithium fluoride. An efficient, imaging photoelectron spectrometer is coupled with a state-of-the-art undulator beam line at the Advanced Light Source to allow collection of a large number of data sets. Since it takes only a few seconds to take a picture of the photoelectrons emitted into a 84{degrees} cone, the authors can use photon energies as high as 350 eV where the cross section for photoemission from the valence band is already quite low, but the emitted photoelectrons behave free-electron-like. This make its much easier to locate the origin of the inter-band transitions in momentum space.

  2. Concentrations, profiles, and estimated human exposures for polychlorinated dibenzo-p-dioxins and dibenzofurans from electronic waste recycling facilities and a chemical industrial complex in Eastern China.

    Science.gov (United States)

    Ma, Jing; Kannan, Kurunthachalam; Cheng, Jinping; Horii, Yuichi; Wu, Qian; Wang, Wenhua

    2008-11-15

    Environmental pollution arising from electronic waste (e-waste) disposal and recycling has received considerable attention in recent years. Treatment, at low temperatures, of e-wastes that contain polyvinylchloride and related polymers can release polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Although several studies have reported trace metals and polybrominated diphenyl ethers (PBDEs) released from e-waste recycling operations, environmental contamination and human exposure to PCDD/Fs from e-waste recycling operations are less well understood. In this study, electronic shredder waste and dust from e-waste facilities, and leaves and surface soil collected in the vicinity of a large scale e-waste recycling facility in Taizhou, Eastern China, were analyzed for total PCDD/ Fs including 2,3,7,8-substituted congeners. We also determined PCDD/Fs in surface agricultural soils from several provinces in China for comparison with soils from e-waste facilities. Concentrations of total PCDD/Fs were high in all of the matrices analyzed and ranged from 30.9 to 11400 pg/g for shredder waste, 3460 to 9820 pg/g dry weight for leaves, 2560 to 148000 pg/g dry weight for workshop-floor dust, and 854 to 10200 pg/g dry weight for soils. We also analyzed surface soils from a chemical industrial complex (a coke-oven plant, a coal-fired power plant, and a chlor-alkali plant) in Shanghai. Concentrations of total PCDD/Fs in surface soil (44.5-531 pg/g dry wt) from the chemical industrial complex were lower than the concentrations found in soils from e-waste recycling plants, but higher than the concentrations found in agricultural soils. Agricultural soils from six cities in China contained low levels (3.44-33.8 pg/g dry wt) of total PCDD/Fs. Profiles of dioxin toxic equivalents (TEQs) of 2,3,7,8-PCDD/Fs in soils from e-waste facilities in Taizhou differed from the profiles found in agricultural soils. The estimated daily intakes of TEQs of PCDD/ Fs via soil/dust ingestion

  3. Geometries and adiabatic excitation energies of the low-lying valence states of CNC, C{sub 2}N, N{sub 3} and NCO studied with the electron-attached and ionized equation-of-motion coupled-cluster methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Jared A; Piecuch, Piotr; Lutz, Jesse J; Gour, Jeffrey R, E-mail: piecuch@chemistry.msu.edu [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States)

    2011-08-01

    The full and active-space variants of the electron-attached (EA) equation-of-motion (EOM) coupled-cluster (CC) method with up to three-particle-two-hole (3p-2h) excitations in the electron-attaching operator R{sub {mu}}{sup (N+1)} that use the CC singles and doubles (CCSD) approach to obtain the ground state of the reference N-electron closed-shell system, abbreviated as EA-EOMCCSD(3p-2h), and their ionized (IP) counterparts with up to three-hole-two-particle (3h-2p) excitations in the ionizing operator R{sub {mu}}{sup (N-1)}, abbreviated as IP-EOMCCSD(3h-2p), are used to optimize the geometries of the ground and low-lying excited states of four open-shell molecules, CNC, C{sub 2}N, NCO and N{sub 3}, and determine the corresponding adiabatic excitation energies. The full and active-space EA-EOMCCSD(3p-2h) results for the CNC and C{sub 2}N molecules, obtained with the correlation-consistent basis sets as large as cc-pVTZ and cc-pVQZ, respectively, are compared with one another, with the corresponding EA-EOMCCSD(2p-1h) calculations, with the previously generated small basis set EA-EOMCC and symmetry-adapted-cluster configuration-interaction (SAC-CI-SDT-R/PS) data, and, wherever possible, with experiment. The analogous comparison of the full and active-space IP-EOMCCSD(3h-2p) results with the IP-EOMCCSD(2h-1p), SAC-CI-SDT-R/PS and experimental data is performed for the NCO and N{sub 3} molecules. It is shown that the active-space EA-EOMCCSD(3p-2h) and IP-EOMCCSD(3h-2p) approaches using small numbers of active orbitals, which have computational costs that are of the order of the CCSD calculations, provide excitation energies and optimized geometries that are in excellent agreement with the results of the significantly more expensive parent EA-EOMCCSD(3p-2h) and IP-EOMCCSD(3h-2p) calculations, independent of the basis set. It is also demonstrated that the basic EA-EOMCCSD(2p-1h) and IP-EOMCCSD(2h-1p) methods, while generally inadequate for a reliable description of the

  4. Pressure-induced valence anomaly in TmTe probed by resonant inelastic X-ray scattering.

    Science.gov (United States)

    Jarrige, I; Rueff, J-P; Shieh, S R; Taguchi, M; Ohishi, Y; Matsumura, T; Wang, C-P; Ishii, H; Hiraoka, N; Cai, Y Q

    2008-09-19

    The pressure-induced valence transition in TmTe was investigated by resonant inelastic x-ray scattering at the Tm L3 edge, a powerful probe of the rare-earth valent state. The data are analyzed within the Anderson impurity model which yields key parameters such as the Tm 4f-5d hybridization. In addition to the general tendency of the f electrons towards delocalization, we find a plateau in both the Tm valence and hybridization pressure dependences between 4.3 and 6.5 GPa which is interpreted in terms of an n-channel Kondo (NCK) screening process. This behavior is at odds with the usually continuous, single-channel Kondo-like f delocalization while being supported by the seminal calculations of the NCK temperature in Tm ion by Saso et al. Our study raises the interesting possibility that an NCK effect realized in a compressed mixed-valent f system could impede the concomitant electron delocalization.

  5. Resonating Valence Bonds and Mean-Field d-Wave Superconductivity in Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Black-Schaffer, Annica M.

    2010-04-27

    We investigate the possibility of inducing superconductivity in a graphite layer by electronic correlation effects. We use a phenomenological microscopic Hamiltonian which includes nearest neighbor hopping and an interaction term which explicitly favors nearest neighbor spin-singlets through the well-known resonance valence bond (RVB) character of planar organic molecules. Treating this Hamiltonian in mean-field theory, allowing for bond-dependent variation of the RVB order parameter, we show that both s- and d-wave superconducting states are possible. The d-wave solution belongs to a two-dimensional representation and breaks time reversal symmetry. At zero doping there exists a quantum critical point at the dimensionless coupling J/t = 1.91 and the s- and d-wave solutions are degenerate for low temperatures. At finite doping the d-wave solution has a significantly higher T{sub c} than the s-wave solution. By using density functional theory we show that the doping induced from sulfur absorption on a graphite layer is enough to cause an electronically driven d-wave superconductivity at graphite-sulfur interfaces. We also discuss applying our results to the case of the intercalated graphites as well as the validity of a mean-field approach.

  6. On the effect of impurities on resistivity recovery, short-range ordering, and defect migration in electron-irradiated concentrated Fe-Cr alloys

    CERN Document Server

    Nikolaev, A L; Davletshin, A E

    1997-01-01

    The resistivity recovery of pure and impurity-doped (0.2-1.5% Si, 0.15% C+N) concentrated ferritic Fe-Cr alloys after electron irradiation at 50-60 K has been investigated over the temperature range 110-390 K. A fine recovery spectrum structure consisting of five peaks has been observed over the range 135-230 K. Short-range ordering starts with the onset of vacancy long-range migration. Doping with both types of impurity suppresses the recovery spectrum structure over the range 160-220 K in a similar manner. Additional effects of impurity doping on the resistivity recovery caused by deviation from Matthiessen's rule have been analysed. A stage III peak is found at 210 K, and two peaks - at 175 K and 195 K - are interpreted as being due to the vacancy short-range migration. It is supposed that such a manifestation of short-range vacancy migration is due to a strong immobilization of self-interstitial atoms, and suppression of short-range and long-range defect annealing processes in stage I, according to a conf...

  7. Effects of Short-Term Exposure to Sublethal Concentrations of Silver Nanoparticles on Histopathology and Electron Microscope Ultrastructure of Zebrafish (Danio Rerio Gills

    Directory of Open Access Journals (Sweden)

    Borhan Mansouri

    2015-11-01

    Full Text Available Background: The increasing use of nanomaterials and nanoproducts has increased the possibility of contamination of the environment, which may have adverse effects on different organisms. The aim of this study was to evaluate the effects of silver nanoparticles on histopathology and gill ultrastructure of zebrafish (Danio rerio under laboratory conditions. Methods: Zebrafish were exposed to four concentrations of silver nanoparticles (0.0015, 0.00375, 0.0075, and 0.015 mg/l for a period of 4 days. Gill ultrastructure and histopathological changes were studied using scanning electron microscope and haematoxylin - eosin staining. Results: Exposure to silver nanoparticles significantly (P < 0.001 increased the diameter of gill filaments and secondary lamellae, while silver nanoparticles significantly reduced the length of the secondary gills in zebrafish. Moreover, other changes such as vacuolization, dilated and clubbed tips, hyperplasia, edema, fusion, swelling of mucocytes, hypertrophy, and necrosis were observed. The effects of silver nanoparticles in zebrafish gills were dose dependent. Conclusion: Based on the adverse effects of AgNPs on zebrafish gills, silver nanoparticle solutions can be hazardous pollutants for the environment.

  8. Kaon semileptonic decay form factors with HISQ valence quarks

    CERN Document Server

    Gamiz, E; Bazavov, A; Bernard, C; Bouchard, C; DeTar, C; Du, D; El-Khadra, A X; Foley, J; Freeland, E D; Gottlieb, Steven; Heller, U M; Kim, J; Kronfeld, A S; Laiho, J; Levkova, L; Mackenzie, P B; Neil, E T; Oktay, M B; Qiu, Si-Wei; Simone, J N; Sugar, R; Toussaint, D; Van de Water, R S; Zhou, R

    2012-01-01

    We report on the status of our kaon semileptonic form factor calculations using the highly-improved staggered quark (HISQ) formulation to simulate the valence fermions. We present results for the form factor f_+^{K \\pi}(0) on the asqtad N_f=2+1 MILC configurations, discuss the chiral-continuum extrapolation, and give a preliminary estimate of the total error. We also present a more preliminary set of results for the same form factor but with the sea quarks also simulated with the HISQ action; these results include data at the physical light quark masses. The improvements that we expect to achieve with the use of the HISQ configurations and simulations at the physical quark masses are briefly discussed.

  9. Nature of the Frequency Shift of Hydrogen Valence Vibrations

    CERN Document Server

    Zhyganiuk, I V

    2015-01-01

    The physical nature of a frequency shift of hydrogen valence vibrations in a water molecule due to its interaction with neighbor molecules has been studied. Electrostatic forces connected with the multipole moments of molecules are supposed to give a dominating contribution to the intermolecular interaction. The frequency shift was calculated in the case where two neighbor molecules form a dimer. The obtained result is in qualitative agreement with the frequency shifts observed for water vapor, hexagonal ice, and liquid water, as well as for aqueous solutions of alcohols. This fact testifies to the electrostatic nature of H-bonds used to describe both the specific features of the intermolecular interaction in water and the macroscopic properties of the latter.

  10. Electric field control of valence tautomeric interconversion in cobalt dioxolene.

    Science.gov (United States)

    Droghetti, A; Sanvito, S

    2011-07-22

    We demonstrate that the critical temperature for valence tautomeric interconversion in cobalt dioxolene complexes can be significantly changed when a static electric field is applied to the molecule. This is achieved by effectively manipulating the redox potential of the metallic acceptor forming the molecule. Importantly, our accurate density functional theory calculations demonstrate that already a field of 0.1  V/nm, achievable in Stark spectroscopy experiments, can produce a change in the critical temperature for the interconversion of 20 K. Our results indicate a new way for switching on and off the magnetism in a magnetic molecule. This offers the unique chance of controlling magnetism at the atomic scale by electrical means.

  11. Time flies with music whatever its emotional valence.

    Science.gov (United States)

    Droit-Volet, Sylvie; Bigand, Emmanuel; Ramos, Danilo; Bueno, José Lino Oliveira

    2010-10-01

    The present study used a temporal bisection task to investigate whether music affects time estimation differently from a matched auditory neutral stimulus, and whether the emotional valence of the musical stimuli (i.e., sad vs. happy music) modulates this effect. The results showed that, compared to sine wave control music, music presented in a major (happy) or a minor (sad) key shifted the bisection function toward the right, thus increasing the bisection point value (point of subjective equality). This indicates that the duration of a melody is judged shorter than that of a non-melodic control stimulus, thus confirming that "time flies" when we listen to music. Nevertheless, sensitivity to time was similar for all the auditory stimuli. Furthermore, the temporal bisection functions did not differ as a function of musical mode. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. Mechanisms of valence selectivity in biological ion channels.

    Science.gov (United States)

    Corry, B; Chung, S-H

    2006-02-01

    Transmembrane ion channels play a crucial role in the existence of all living organisms. They partition the exterior from the interior of the cell, maintain the proper ionic gradient across the cell membrane and facilitate signaling between cells. To perform these functions, ion channels must be highly selective, allowing some types of ions to pass while blocking the passage of others. Here we review a number of studies that have helped to elucidate the mechanisms by which ion channels discriminate between ions of differing charge, focusing on four channel families as examples: gramicidin, ClC chloride, voltage-gated calcium and potassium channels. The recent availability of high-resolution structural data has meant that the specific inter-atomic interactions responsible for valence selectivity can be pinpointed. Not surprisingly, electrostatic considerations have been shown to play an important role in ion specificity, although many details of the origins of this discrimination remain to be determined.

  13. Electric Crosstalk Effect in Valence Change Resistive Random Access Memory

    Science.gov (United States)

    Sun, Jing; Wang, Hong; Wu, Shiwei; Song, Fang; Wang, Zhan; Gao, Haixia; Ma, Xiaohua

    2017-08-01

    Electric crosstalk phenomenon in valence change resistive switching memory (VCM) is systematically investigated. When a voltage is applied on the VCM device, an electric field is formed in the isolated region between the devices, which causes the oxygen vacancies in conductive filaments (CFs) to drift apart, leading to a consequent resistance degradation of the neighboring devices. The effects of distance between memory cells, electrodes widths and physical dimensions of CFs on the memory performance are investigated in this work. Furthermore, the strategies to mitigate electric crosstalk effects are developed. According to the simulation results, the crosstalk phenomenon can become more severe as the distance between memory cells or the electrode width decreases. In order to optimize the device performance, it is helpful to control the location of the break points of CFs in the device close to the top electrode. Alternatively, taking the integration density into account, switching materials with a small field accelerated parameter can also contribute to obtaining a stable performance.

  14. Aging and long-term memory for emotionally valenced events.

    Science.gov (United States)

    Breslin, Carolyn W; Safer, Martin A

    2013-06-01

    In 2008, 1103 ardent Boston Red Sox fans answered questions about their team's 2003 loss and 2004 win in baseball championship games with archrival New York Yankees. Contrary to predictions based on socioemotional selectivity theory, there were no significant interactions of age and event valence for accuracy in remembering event details, or for self-reported subjective vividness and rehearsal of the memories. Fans 65 years and older tended to remember feeling only sad about the 2003 loss, whereas fans 25 years and under tended to remember feeling both sad and angry. Individuals may remember emotional feelings based on remembered goals about an event. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  15. Dissociative and non-dissociative photoionization of molecular fluorine from inner and valence shells

    Energy Technology Data Exchange (ETDEWEB)

    Ayuso, D.; Palacios, A. [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Decleva, P. [Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, 34127 Trieste (Italy); CNR-IOM, Trieste (Italy); Martín, F., E-mail: fernando.martin@uam.es [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Instituto Madrileño de Estudios Avanzados en Nanociencia, Cantoblanco, 28049 Madrid (Spain)

    2014-08-15

    Highlights: • We theoretically analyze the angle-integrated photoionization cross sections of the fluorine molecule, which have been computed up to hundreds of eV using a DFT-like methodology that takes into account the nuclear degrees of freedom. • We have considered electron ejection from all the molecular orbitals and found that the corresponding cross sections show an oscillatory behavior as a function of the photoelectron momentum, which is the result of the double-slit type interferences. • We further compute dissociative and non-dissociative ionization channels. • Dissociative ionization is negligible in other diatomic molecules such N{sub 2} or CO, whereas is visible for F{sub 2} when the electron is ejected from the 1u or the 3σ{sub g} molecular orbitals. - Abstract: We present a theoretical study of F{sub 2} photoionization in the range 0–40 a.u. of photoelectron energy, where the undulatory behavior of the corresponding angle-integrated cross sections due to electron emission from equivalent centers is apparent. These double-slit type interferences are observed in both inner- and valence-shell ionization. We analyze confinement effects that appear at given energies when the electron is ejected parallel to the molecular axis. Since we account for the nuclear degrees of freedom, we evaluate and discuss the vibrationally resolved cross sections, including both dissociative and non-dissociative ionization channels. We also analyze the ratios between the latter cross sections and the relationship between the observed oscillations and the structure of the molecule.

  16. Valence-Bond Concepts in Coordination Chemistry and the Nature of Metal-Metal Bonds.

    Science.gov (United States)

    Pauling, Linus; Herman, Zelek S.

    1984-01-01

    Discusses the valence-bond method, applying it to some coordination compounds of metals, especially those involving metal-metal bonds. Suggests that transition metals can form as many as nine covalent bonds, permitting valence-theory to be extended to transition metal compounds in a more effective way than has been possible before. (JN)

  17. Dissociable Modulation of Overt Visual Attention in Valence and Arousal Revealed by Topology of Scan Path

    Science.gov (United States)

    Ni, Jianguang; Jiang, Huihui; Jin, Yixiang; Chen, Nanhui; Wang, Jianhong; Wang, Zhengbo; Luo, Yuejia; Ma, Yuanye; Hu, Xintian

    2011-01-01

    Emotional stimuli have evolutionary significance for the survival of organisms; therefore, they are attention-grabbing and are processed preferentially. The neural underpinnings of two principle emotional dimensions in affective space, valence (degree of pleasantness) and arousal (intensity of evoked emotion), have been shown to be dissociable in the olfactory, gustatory and memory systems. However, the separable roles of valence and arousal in scene perception are poorly understood. In this study, we asked how these two emotional dimensions modulate overt visual attention. Twenty-two healthy volunteers freely viewed images from the International Affective Picture System (IAPS) that were graded for affective levels of valence and arousal (high, medium, and low). Subjects' heads were immobilized and eye movements were recorded by camera to track overt shifts of visual attention. Algebraic graph-based approaches were introduced to model scan paths as weighted undirected path graphs, generating global topology metrics that characterize the algebraic connectivity of scan paths. Our data suggest that human subjects show different scanning patterns to stimuli with different affective ratings. Valence salient stimuli (with neutral arousal) elicited faster and larger shifts of attention, while arousal salient stimuli (with neutral valence) elicited local scanning, dense attention allocation and deep processing. Furthermore, our model revealed that the modulatory effect of valence was linearly related to the valence level, whereas the relation between the modulatory effect and the level of arousal was nonlinear. Hence, visual attention seems to be modulated by mechanisms that are separate for valence and arousal. PMID:21494331

  18. Atoms in Valence Bond – AiVB : synopsis and test results

    NARCIS (Netherlands)

    Zielinski, M.L.; van Lenthe, J.H.

    2010-01-01

    The Atoms in Valence Bond (AiVB) method, a new approach in the Valence Bond, is introduced. This approach combines the ideas behind the early Atoms in Molecules (AIM) developments, e.g. by Moffit [21], to understand a molecular wave function in terms of proper atomic wave functions, with the

  19. Application of circular dichroism spectroscopy in the study of mixed-valence asymmetric ruthenium polypyridyl complexes

    NARCIS (Netherlands)

    Ahmed, Hamid M. Y.; Coburn, Nadia; Dini, Danilo; de Jong, Jaap J. D.; Villani, Claudio; Browne, Wesley R.; Vos, Johannes G.

    2011-01-01

    Circular dichroism (CD) spectroelectrochemistry is used to determine the extent of singly occupied molecular orbital delocalization in mixed-valence multinuclear complexes, specifically the mixed-valence (RuRuIII)-Ru-II states of the four diastereoisomers of [(Ru(bpy)(2))(2)(bpt)](3+) [1; bpy =

  20. Effects of Emotional Valence and Arousal on Recollective and Nonrecollective Recall

    Science.gov (United States)

    Gomes, Carlos F. A.; Brainerd, Charles J.; Stein, Lilian M.

    2013-01-01

    The authors investigated the effects of valence and arousal on memory using a dual-process model that quantifies recollective and nonrecollective components of recall without relying on metacognitive judgments to separate them. The results showed that valenced words increased reconstruction (a component of nonrecollective retrieval) relative to…

  1. Does emotional valence affect performance in non-emotional categorization tasks?

    NARCIS (Netherlands)

    Rinck, M.; Becker, E.S.

    2009-01-01

    In five experiments, a categorization task was used to test whether threatening emotional valence would automatically affect reactions, even when valence is task-irrelevant. Financial threat words (e.g., debts) required the same response as either anxiety words or pleasant words. In the first three

  2. The Effect of Stimulus Valence on Lexical Retrieval in Younger and Older Adults

    Science.gov (United States)

    Blackett, Deena Schwen; Harnish, Stacy M.; Lundine, Jennifer P.; Zezinka, Alexandra; Healy, Eric W.

    2017-01-01

    Purpose: Although there is evidence that emotional valence of stimuli impacts lexical processes, there is limited work investigating its specific impact on lexical retrieval. The current study aimed to determine the degree to which emotional valence of pictured stimuli impacts naming latencies in healthy younger and older adults. Method: Eighteen…

  3. SPIN POLARIZATION AND MAGNETIC DICHROISM IN PHOTOEMISSION FROM CORE AND VALENCE STATES IN LOCALIZED MAGNETIC SYSTEMS

    NARCIS (Netherlands)

    THOLE, BT; VANDERLAAN, G

    1991-01-01

    Using group theory we derive a general model for spin polarization and magnetic dichroism in photo-emission in the presence of atomic interactions between the hole created and the valence holes. We predict strong effects in the photoemission from core levels and localized valence levels of

  4. Dissociable modulation of overt visual attention in valence and arousal revealed by topology of scan path.

    Directory of Open Access Journals (Sweden)

    Jianguang Ni

    Full Text Available Emotional stimuli have evolutionary significance for the survival of organisms; therefore, they are attention-grabbing and are processed preferentially. The neural underpinnings of two principle emotional dimensions in affective space, valence (degree of pleasantness and arousal (intensity of evoked emotion, have been shown to be dissociable in the olfactory, gustatory and memory systems. However, the separable roles of valence and arousal in scene perception are poorly understood. In this study, we asked how these two emotional dimensions modulate overt visual attention. Twenty-two healthy volunteers freely viewed images from the International Affective Picture System (IAPS that were graded for affective levels of valence and arousal (high, medium, and low. Subjects' heads were immobilized and eye movements were recorded by camera to track overt shifts of visual attention. Algebraic graph-based approaches were introduced to model scan paths as weighted undirected path graphs, generating global topology metrics that characterize the algebraic connectivity of scan paths. Our data suggest that human subjects show different scanning patterns to stimuli with different affective ratings. Valence salient stimuli (with neutral arousal elicited faster and larger shifts of attention, while arousal salient stimuli (with neutral valence elicited local scanning, dense attention allocation and deep processing. Furthermore, our model revealed that the modulatory effect of valence was linearly related to the valence level, whereas the relation between the modulatory effect and the level of arousal was nonlinear. Hence, visual attention seems to be modulated by mechanisms that are separate for valence and arousal.

  5. Identifying Facial Emotions: Valence Specific Effects and an Exploration of the Effects of Viewer Gender

    Science.gov (United States)

    Jansari, Ashok; Rodway, Paul; Goncalves, Salvador

    2011-01-01

    The valence hypothesis suggests that the right hemisphere is specialised for negative emotions and the left hemisphere is specialised for positive emotions (Silberman & Weingartner, 1986). It is unclear to what extent valence-specific effects in facial emotion perception depend upon the gender of the perceiver. To explore this question 46…

  6. Electronic band gap reduction and intense luminescence in Co and Mn ion-implanted SiO2

    Science.gov (United States)

    Green, R. J.; Zatsepin, D. A.; St. Onge, D. J.; Kurmaev, E. Z.; Gavrilov, N. V.; Zatsepin, A. F.; Moewes, A.

    2014-03-01

    Cobalt and manganese ions are implanted into SiO2 over a wide range of concentrations. For low concentrations, the Co atoms occupy interstitial locations, coordinated with oxygen, while metallic Co clusters form at higher implantation concentrations. For all concentrations studied here, Mn ions remain in interstitial locations and do not cluster. Using resonant x-ray emission spectroscopy and Anderson impurity model calculations, we determine the strength of the covalent interaction between the interstitial ions and the SiO2 valence band, finding it comparable to Mn and Co monoxides. Further, we find an increasing reduction in the SiO2 electronic band gap for increasing implantation concentration, due primarily to the introduction of Mn- and Co-derived conduction band states. We also observe a strong increase in a band of x-ray stimulated luminescence at 2.75 eV after implantation, attributed to oxygen deficient centers formed during implantation.

  7. Single and double valence configuration interactions for recovering the exponential decay law while tunneling through a molecular wire

    Science.gov (United States)

    Portais, Mathilde; Hliwa, Mohamed; Joachim, Christian

    2016-01-01

    The exponential decay of the electronic transmission through a molecular wire with its length is calculated using a configuration interaction elastic scattering quantum chemistry (CI-ESQC) theory [1, 2]. In the HOMO-LUMO gap and in a one-electron approximation, this decay is exponential since the scattering matrix comes from a product of spatial propagators along the wire. In a valence SD-CI (single and double-configurations interaction) description, such a product does not exist. An effective one was numerically obtained from the CI-ESQC scattering matrix. Fluctuations over the effective CI-exponential decay come from the truncation of the full CI basis set and also from many-body exchange-correlation effects along the molecular wire.

  8. Influence of emotional valence and arousal on the spread of activation in memory.

    Science.gov (United States)

    Jhean-Larose, Sandra; Leveau, Nicolas; Denhière, Guy

    2014-11-01

    Controversy still persists on whether emotional valence and arousal influence cognitive activities. Our study sought to compare how these two factors foster the spread of activation within the semantic network. In a lexical decision task, prime words were varied depending on the valence (pleasant or unpleasant) or on the level of emotional arousal (high or low). Target words were carefully selected to avoid semantic priming effects, as well as to avoid arousing specific emotions (neutral). Three SOA durations (220, 420 and 720 ms) were applied across three independent groups. Results indicate that at 220 ms, the effect of arousal is significantly higher than the effect of valence in facilitating spreading activation while at 420 ms, the effect of valence is significantly higher than the effect of arousal in facilitating spreading activation. These findings suggest that affect is a sequential process involving the successive intervention of arousal and valence.

  9. Pressure-induced anomalous valence crossover in cubic YbCu5-based compounds.

    Science.gov (United States)

    Yamaoka, Hitoshi; Tsujii, Naohito; Suzuki, Michi-To; Yamamoto, Yoshiya; Jarrige, Ignace; Sato, Hitoshi; Lin, Jung-Fu; Mito, Takeshi; Mizuki, Jun'ichiro; Sakurai, Hiroya; Sakai, Osamu; Hiraoka, Nozomu; Ishii, Hirofumi; Tsuei, Ku-Ding; Giovannini, Mauro; Bauer, Ernst

    2017-07-19

    A pressure-induced anomalous valence crossover without structural phase transition is observed in archetypal cubic YbCu5 based heavy Fermion systems. The Yb valence is found to decrease with increasing pressure, indicating a pressure-induced crossover from a localized 4f 13 state to the valence fluctuation regime, which is not expected for Yb systems with conventional c-f hybridization. This result further highlights the remarkable singularity of the valence behavior in compressed YbCu5-based compounds. The intermetallics Yb2Pd2Sn, which shows two quantum critical points (QCP) under pressure and has been proposed as a potential candidate for a reentrant Yb2+ state at high pressure, was also studied for comparison. In this compound, the Yb valence monotonically increases with pressure, disproving a scenario of a reentrant non-magnetic Yb2+ state at the second QCP.

  10. Magnetoinduced valence transition in EuNi sub 2 (Si sub 1 sub - sub x Ge sub x) sub 2 in fields up to 500 T

    CERN Document Server

    Platonov, V V; Selemir, V D; Shiga, M

    2002-01-01

    One measured critical fields of magnetic field induced valent transition in EuNi sub 2 (Si sub 1 sub - sub x Ge sub x) sub 2 compound within intermediate valence range with x 0.5-0.75. Measurements of magnetic susceptibility were conducted under helium temperature in up to 600 T fields. It is shown that magnitude of critical field increases linearly with decrease of germanium concentration

  11. Intervalence charge transfer transition in mixed valence complexes ...

    Indian Academy of Sciences (India)

    Unknown

    inclusion complex; optical electron transfer; cyclodextrin. 1. Introduction. Experimental and theoretical study of intervalence electron transfer between two metal centres linked by a spacer group, through which electron transfer can takes place, is an area of contemporary research interest. The consequence of this process ...

  12. Logarithmic temperature dependence of samarium ion valence in the heavy-fermion S mxL a1 -xO s4S b12

    Science.gov (United States)

    Fushiya, Kengo; Miyazaki, Ryoichi; Higashinaka, Ryuji; Yamada, Akira; Mizumaki, Masaichiro; Tsutsui, Satoshi; Nitta, Kiyofumi; Uruga, Tomoya; Suemitsu, Bunya; Sato, Hideyuki; Aoki, Yuji

    2015-08-01

    We have measured x-ray absorption spectra at the Sm L3 edge to investigate the Sm-ion valence of (S mxL a1 -x) O s4S b12 , in which field-insensitive heavy-fermion behavior appears at low temperatures for x =1 . It has been found that the Sm-ion valance shifts to 2 + with La ion substitution; from v =+2.78 (x =1 ) to v =+2.73 (x =0.2 ) at 10 K. For all x investigated, its temperature dependence shows a logT behavior, indicating that the valence change is caused by "an unconventional Kondo effect" associated with Sm 4 f -electron charge degrees of freedom. Almost x independence of "the associated Kondo temperature" (T˜K=56 ±10 K ) indicates that the Kondo effect has a local nature, attributable to the cage structure of the filled skutterudite.

  13. Entanglement in valence-bond-solid states and quantum search

    Science.gov (United States)

    Xu, Ying

    The present dissertation covers two independent subjects: (i) The quantum entanglement in Valence-Bond-Solid states, and (ii) quantum database search algorithms. Both subjects are presented in a self-contained and pedagogical way. (i) The first chapter is a through introduction to the subject of quantum entanglement in Valence-Bond-Solid (VBS) states defined on a lattice or graph. The VBS state was first introduced as the ground state of the celebrated Affleck-Kennedy-Lieb-Tasaki (AKLT) spin chain model in statistical mechanics. Then it became essential in condensed matter physics, quantum information and measurement-based quantum computation. Recent studies elucidated important entanglement properties of the VBS state. We start with the definition of a general AKLT model and the construction of VBS ground states. A subsystem is introduced and described by the density matrix. Exact spectrum properties of the density matrix are proved and discussed. Density matrices of 1-dimensional models are diagonalized and the entanglement entropies (the von Neumann entropy and Renyi entropy) are calculated. The entropies take saturated value and the density matrix is proportional to a projector in the large subsystem limit. (ii) The second chapter is a detailed introduction to the subject of quantum database search algorithms. The problem of searching a large database (a Hilbert space) for a target item is performed by the famous Grover algorithm which locates the target item with probability 1 and a quadratic speed up compared with the corresponding classical algorithm. If the database is partitioned into blocks and one is searching for the block containing the target item instead of the target item itself, then the problem is referred to as partial search. Partial search trades accuracy for speed and the most efficient version is the Grover-Radhakrishnan-Korepin (GRK) algorithm. The target block can be further partitioned into subblocks so that GRK can be performed in a

  14. Structural, electronic properties, and quantum capacitance of B, N and P-doped armchair carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi-Khoshdel, S. Morteza, E-mail: mmousavi@iust.ac.ir [Department of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jahanbakhsh-bonab, Parisa [Department of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Targholi, Ehsan [Young Researchers and Elite Club, Abhar Branch, Islamic Azad University, Abhar (Iran, Islamic Republic of)

    2016-10-07

    Using DFT calculations, we study the structural parameters, electronic properties and quantum capacitance of N, B, and P-doped armchair carbon nanotubes (CNTs). Fermi level shifts towards conduction band and valence band in N- and B-doped CNTs, respectively. While in the case of P atom, despite having an extra valence electron than carbon, there is no shift in Fermi level. The results revealed from a symmetric capacitance enhancement in P-doped CNT and an asymmetric capacitance enhancement in B and N-doped CNTs. The greatest amount of quantum capacitance of N-doped (6, 6) CNT could be achieved at the concentration range of 0.1–0.15. - Highlights: • Exploration of variation in quantum capacitance of CNTs through doping N, B and P atoms. • Quantum capacitance of CNTs is sensitive to impurities entered in carbon nanotubes. • Maximum quantum capacitance of N-doped CNTs is achieved at the concentration range of 0.1–0.15.

  15. Photo-induced valence change of the sulfur atom in an L-cysteine thin film grown on a silver metal substrate in a saliva-emulated aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Tsujibayashi, Toru [Department of Physics, Osaka Dental University, 8-1 Kuzuha-hanazono, Hirakata, Osaka 573-1121 (Japan); Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao [Synchrotron Light Application Center, Saga University, 1 Honjo, Saga, Saga 840-8502 (Japan)

    2015-04-27

    A thin film of L-cysteine (HSCH{sub 2}CH(NH{sub 2})COOH) is grown on a silver substrate in saliva-emulated aqueous solution. X-ray photoemission spectroscopic measurements have revealed that the sulfur atom shows valence change under IR laser irradiation at 825 nm. The valence change maintains for about a minute at room temperature and more than an hour between 110 and 250 K after stopping the laser irradiation. It is not observed at all at temperatures lower than 110 K. This temperature-dependent behavior indicates that the photo-excited electronic change should be accompanied by a conformational change in the L-cysteine molecule. It is strongly suggested that the reversible valence change of the sulfur atom is applicable to a memory used around room temperature.

  16. Theoretical and experimental study of high-magnetic-field XMCD spectra at the L{sub 2,3} absorption edges of mixed-valence rare-earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kotani, Akio [Photon Factory, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Matsuda, Yasuhiro H [Institute for Solid State Physics, University of Tokyo, Chiba 277-8581 (Japan); Nojiri, Hiroyuki, E-mail: kotani@post.kek.j [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2009-11-15

    X-ray magnetic circular dichroism(XMCD) spectra at the L{sub 2,3} edges of mixed-valence rare-earth compounds in high magnetic fields are studied both theoretically and experimentally. The theoretical study is based on a new framework proposed recently by Kotani. The Zeeman splitting of 4f states, the mixed-valence character of 4f states, and the 4f-5d exchange interaction are incorporated into a single impurity Anderson model. New XMCD experiments in high magnetic fields up to 40 T are carried out for the mixed-valence compounds EuNi{sub 2}(Si{sub 0.18}Ge{sub 0.82}){sub 2} and YbInCu{sub 4} by using a miniature pulsed magnet, which was developed recently by Matsuda et al. The XMCD data are taken at 5 K by transmission measurements for incident X-rays with {+-} helicities at BL39XU in SPring-8. After giving a survey on recent developments in the theory of XMCD spectra for mixed-valence Ce and Yb compounds, we calculate the XMCD spectra of YbInCu{sub 4} at the field-induced valence transition around 32 T by applying the recent theoretical framework and by newly introducing at 32 T a discontinuous change in the Yb 4f level and that in the hybridization strength between the Yb 4f and conduction electrons. The calculated results are compared with the experimental ones.

  17. Influence of orbital contributions to the valence band alignment of Bi2O3, Fe2O3, BiFeO3, and Bi0.5Na0.5TiO3

    Science.gov (United States)

    Li, Shunyi; Morasch, Jan; Klein, Andreas; Chirila, Christina; Pintilie, Lucian; Jia, Lichao; Ellmer, Klaus; Naderer, Michael; Reichmann, Klaus; Gröting, Melanie; Albe, Karsten

    2013-07-01

    The formation of an interface between Bi2O3, Fe2O3, BiFeO3, Bi0.5Na0.5TiO3, and the high work function metallic RuO2 is studied using photoelectron spectroscopy with in situ RuO2 deposition. Schottky barrier heights are derived and the valence band maximum energies of the studied materials are aligned with respect to each other as well as to other functional oxides like SrTiO3 and PbTiO3. The energy band alignment follows systematic trends compared to a large number of oxides, and can be understood in terms of the contribution of Fe 3d and Bi 6s/6p (lone pair) orbitals to electronic states near the valence band maximum. The results indicate that the valence band maxima are largely determined by the local environment of the cations, which allows to estimate valence band maximum energies of oxides with multiple cations from those of their parent binary compounds. The high valence band maximum of BiFeO3 is consistent with reported p-type conduction of acceptor doped material, while the high conduction band minimum makes n-type conduction unlikely.

  18. Valence Scaling of Dynamic Facial Expressions Is Altered in High-Functioning Subjects with Autism Spectrum Disorders: An FMRI Study

    Science.gov (United States)

    Rahko, Jukka S.; Paakki, Jyri-Johan; Starck, Tuomo H.; Nikkinen, Juha; Pauls, David L.; Katsyri, Jari V.; Jansson-Verkasalo, Eira M.; Carter, Alice S.; Hurtig, Tuula M.; Mattila, Marja-Leena; Jussila, Katja K.; Remes, Jukka J.; Kuusikko-Gauffin, Sanna A.; Sams, Mikko E.; Bolte, Sven; Ebeling, Hanna E.; Moilanen, Irma K.; Tervonen, Osmo; Kiviniemi, Vesa

    2012-01-01

    FMRI was performed with the dynamic facial expressions fear and happiness. This was done to detect differences in valence processing between 25 subjects with autism spectrum disorders (ASDs) and 27 typically developing controls. Valence scaling was abnormal in ASDs. Positive valence induces lower deactivation and abnormally strong activity in ASD…

  19. Lying about the valence of affective pictures: an fMRI study.

    Directory of Open Access Journals (Sweden)

    Tatia M C Lee

    Full Text Available The neural correlates of lying about affective information were studied using a functional magnetic resonance imaging (fMRI methodology. Specifically, 13 healthy right-handed Chinese men were instructed to lie about the valence, positive or negative, of pictures selected from the International Affective Picture System (IAPS while their brain activity was scanned by a 3T Philip Achieva scanner. The key finding is that the neural activity associated with deception is valence-related. Comparing to telling the truth, deception about the valence of the affectively positive pictures was associated with activity in the inferior frontal, cingulate, inferior parietal, precuneus, and middle temporal regions. Lying about the valence of the affectively negative pictures, on the other hand, was associated with activity in the orbital and medial frontal regions. While a clear valence-related effect on deception was observed, common neural regions were also recruited for the process of deception about the valence of the affective pictures. These regions included the lateral prefrontal and inferior parietal regions. Activity in these regions has been widely reported in fMRI studies on deception using affectively-neutral stimuli. The findings of this study reveal the effect of valence on the neural activity associated with deception. Furthermore, the data also help to illustrate the complexity of the neural mechanisms underlying deception.

  20. Vivid: How valence and arousal influence word processing under different task demands

    Science.gov (United States)

    Delaney-Busch, Nathaniel; Wilkie, Gianna; Kuperberg, Gina

    2016-01-01

    In this study, we used event-related potentials (ERPs) to examine how dimensions of emotion – valence and arousal – influence different stages of word processing under different task demands. In two experiments, two groups of participants viewed the same single emotional and neutral words while carrying out different tasks. In both experiments, valence (pleasant, unpleasant, and neutral) was fully crossed with arousal (high and low). We found that task made a substantial contribution to how valence and arousal modulated the Late Positive Complex (LPC), which is thought to reflect sustained evaluative processing (particularly of emotional stimuli). When participants performed a semantic categorization task in which emotion was not directly relevant to task performance, the LPC showed a larger amplitude for high-arousal words than low-arousal words, but no effect of valence. In contrast, when participants performed an overt valence categorization task, the LPC showed a large effect of valence (with unpleasant words eliciting the largest positivity), but no effect of arousal. These data show not only that valence and arousal act independently to influence word processing, but that their relative contributions to prolonged evaluative neural processes are strongly influenced by situational demands (and individual differences, as revealed in a subsequent analysis of subjective judgments). PMID:26833048

  1. From Semantics to Feelings: How Do Individuals with Schizophrenia Rate the Emotional Valence of Words?

    Directory of Open Access Journals (Sweden)

    Ana P. Pinheiro

    2012-01-01

    Full Text Available Schizophrenia is characterized by both emotional and language abnormalities. However, in spite of reports of preserved evaluation of valence of affective stimuli, such as pictures, it is less clear how individuals with schizophrenia assess verbal material with emotional valence, for example, the overall unpleasantness/displeasure relative to pleasantness/attraction of a word. This study aimed to investigate how schizophrenic individuals rate the emotional valence of adjectives, when compared with a group of healthy controls. One hundred and eighty-four adjectives differing in valence were presented. These adjectives were previously categorized as “neutral,” “positive” (pleasant, or “negative” (unpleasant by five judges not participating in the current experiment. Adjectives from the three categories were matched on word length, frequency, and familiarity. Sixteen individuals with schizophrenia diagnosis and seventeen healthy controls were asked to rate the valence of each word, by using a computerized version of the Self-Assessment Manikin (Bradley and Lang, 1994. Results demonstrated similar ratings of emotional valence of words, suggesting a similar representation of affective knowledge in schizophrenia, at least in terms of the valence dimension.

  2. Room Temperature Magnetic Switchability Assisted by Hysteretic Valence Tautomerism in a Layered Two-Dimensional Manganese-Radical Coordination Framework.

    Science.gov (United States)

    Lannes, Anthony; Suffren, Yan; Tommasino, Jean Bernard; Chiriac, Rodica; Toche, François; Khrouz, Lhoussain; Molton, Florian; Duboc, Carole; Kieffer, Isabelle; Hazemann, Jean-Louis; Reber, Christian; Hauser, Andreas; Luneau, Dominique

    2016-12-21

    The manganese-nitronyl-nitroxide two-dimensional coordination polymer {[Mn2(NITIm)3]ClO4}n (1) (NITImH = 2-(2-imidazolyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-3-oxide-1-oxyl) undergoes an unusual hysteretic thermo-induced valence tautomeric transition near room temperature, during which the manganese(II) ions are oxidized to manganese(III) and two of the three deprotonated radicals (NITIm-) are reduced to their diamagnetic aminoxyl form (denoted NITRed2-). Upon cooling, the high-temperature species {[MnII2(NITIm)3]ClO4}n (1HT) turns into the low-temperature species {[MnIII2(NITRed)2(NITIm)]ClO4}n (1LT) around 274 K, while on heating the process is reversed at about 287 K. This valence tautomeric phenomenon is supported by temperature-dependent magnetic susceptibility measurements, differential scanning calorimetry (DSC), crystal structure determination, UV-vis absorption, X-ray absorption (XAS), and emission (XES) and electron paramagnetic resonance (EPR) spectroscopies in the solid state.

  3. The mixed-valence state of Ce in the hexagonal CeNi sub 4 B compound

    CERN Document Server

    Tolinski, T; Pugaczowa-Michalska, M; Chelkowska, G

    2003-01-01

    Measurements of the magnetic susceptibility chi, x-ray photoemission spectra (XPS), electrical resistivity rho and electronic structure calculations for CeNi sub 4 B are reported. In the paramagnetic region, CeNi sub 4 B follows the Curie-Weiss law with mu sub e sub f sub f = 0.52 mu sub B /fu and theta -10.7 K. The effective magnetic moment is lower than the free Ce sup 3 sup + -ion value. The Ce(3d) XPS spectra have confirmed the mixed-valence state of Ce ions in CeNi sub 4 B. The f occupancy, n sub f , and the coupling DELTA between the f level and the conduction states were derived to be about 0.83 and 85 meV, respectively. Both susceptibility data and XPS spectra show that Ce ions in CeNi sub 4 B are in the intermediate-valence state. At low temperatures (below 12 K), the magnetic contribution to the electrical resistivity reveals a logarithmic slope characteristic of Kondo-like systems.

  4. Translation-Invariant Parent Hamiltonians of Valence Bond Crystals

    Science.gov (United States)

    Huerga, Daniel; Greco, Andrés; Gazza, Claudio; Muramatsu, Alejandro

    2017-04-01

    We present a general method to construct translation-invariant and SU(2) symmetric antiferromagnetic parent Hamiltonians of valence bond crystals (VBCs). The method is based on a canonical mapping transforming S =1 /2 spin operators into a bilinear form of a new set of dimer fermion operators. We construct parent Hamiltonians of the columnar and the staggered VBCs on the square lattice, for which the VBC is an eigenstate in all regimes and the exact ground state in some region of the phase diagram. We study the departure from the exact VBC regime upon tuning the anisotropy by means of the hierarchical mean field theory and exact diagonalization on finite clusters. In both Hamiltonians, the VBC phase extends over the exact regime and transits to a columnar antiferromagnet (CAFM) through a window of intermediate phases, revealing an intriguing competition of correlation lengths at the VBC-CAFM transition. The method can be readily applied to construct other VBC parent Hamiltonians in different lattices and dimensions.

  5. The genetics of anxiety-related negative valence system traits.

    Science.gov (United States)

    Savage, Jeanne E; Sawyers, Chelsea; Roberson-Nay, Roxann; Hettema, John M

    2017-03-01

    NIMH's Research Domain Criteria (RDoC) domain of negative valence systems (NVS) captures constructs of negative affect such as fear and distress traditionally subsumed under the various internalizing disorders. Through its aims to capture dimensional measures that cut across diagnostic categories and are linked to underlying neurobiological systems, a large number of phenotypic constructs have been proposed as potential research targets. Since "genes" represent a central "unit of analysis" in the RDoC matrix, it is important for studies going forward to apply what is known about the genetics of these phenotypes as well as fill in the gaps of existing knowledge. This article reviews the extant genetic epidemiological data (twin studies, heritability) and molecular genetic association findings for a broad range of putative NVS phenotypic measures. We find that scant genetic epidemiological data is available for experimentally derived measures such as attentional bias, peripheral physiology, or brain-based measures of threat response. The molecular genetic basis of NVS phenotypes is in its infancy, since most studies have focused on a small number of candidate genes selected for putative association to anxiety disorders (ADs). Thus, more research is required to provide a firm understanding of the genetic aspects of anxiety-related NVS constructs. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Effects of Emotional Valence on Hemispheric Asymmetries in Response Inhibition

    Directory of Open Access Journals (Sweden)

    Sebastian Ocklenburg

    2017-08-01

    Full Text Available Hemispheric asymmetries are a major organizational principle in human emotion processing, but their interaction with prefrontal control processes is not well understood. To this end, we determined whether hemispheric differences in response inhibition depend on the emotional valence of the stimulus being inhibited. Participants completed a lateralised Go/Nogo task, in which Nogo stimuli were neutral or emotional (either positive or negative images, while Go stimuli were scrambled versions of the same pictures. We recorded the N2 and P3 event-related potential (ERP components, two common electrophysiological measures of response inhibition processes. Behaviourally, participants were more accurate in withholding responses to emotional than to neutral stimuli. Electrophysiologically, Nogo-P3 responses were greater for emotional than for neutral stimuli, an effect driven primarily by an enhanced response to positive images. Hemispheric asymmetries were also observed, with greater Nogo-P3 following left versus right visual field stimuli. However, the visual field effect did not interact with emotion. We therefore find no evidence that emotion-related asymmetries affect response inhibition processes.

  7. Aging and distraction by irrelevant speech: does emotional valence matter?

    Science.gov (United States)

    Van Gerven, Pascal W M; Murphy, Dana R

    2010-11-01

    From prior studies, we know that older adults are rarely more distracted by irrelevant speech than younger adults, which is remarkable in light of the inhibitory deficit view of aging. We tested the hypothesis that older adults are more distracted by emotional irrelevant speech during a visual cognitive task than younger adults. Forty-eight younger (mean age = 21.9 years) and 48 older individuals (mean age = 68.1 years) performed a visual counting task while being exposed to irrelevant speech consisting of random numbers intermixed with neutral, positive, or negative words. Performance in these conditions was compared with that in a silence condition. Irrelevant speech increased counting time and decreased accuracy similarly for younger and older adults. Furthermore, the emotional conditions did not elicit a stronger effect than the neutral condition. Finally, we found implicit memory for irrelevant speech, but its level was independent of emotional valence and age. We conclude that emotional irrelevant speech has no disproportionate impact on cognitive performance in older adults. This can be regarded as a challenge to the inhibitory deficit hypothesis.

  8. Titanium oxide modification with oxides of mixed cobalt valence for photo catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Alanis O, R.; Jimenez B, J., E-mail: jaime.jimenez@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2010-07-01

    In the present work, heterogenous photo catalysis, a technique often used for organic compound degradation toxic in water, was used. The photo catalyst most often used in this technique is TiO{sub 2}, which due to its physical and chemical properties, can degrade a great number of organic compounds. In addition, in recent years it has been verified that the doping of semiconductors with metals or metallic oxides increases the photo catalytic activity of these semiconductors, which is why it was proposed for doping by the impregnating method using commercial TiO{sub 2} synthesized by the Degussa company (TiO{sub 2} Degussa P25) with and oxide of mixed cobalt valence (Co{sub 3}O{sub 4}) synthesized using the sol-gel method. The synthesized photo catalyst TiO{sub 2}/Co{sub 3}O{sub 4} was characterized by the techniques of X-ray diffraction, scanning electronic microscopy, Raman spectroscopy and finally, photo catalytic tests by means of the degradation of methylene blue. (Author)

  9. Study on electroluminescence from multiply-stacking valency controlled Si quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Takahisa [Graduate School of Engineering, Nagoya University, Nagoya (Japan); Makihara, Katsunori, E-mail: makihara@nuee.nagoya-u.ac.jp [Graduate School of Engineering, Nagoya University, Nagoya (Japan); Ohta, Akio [Venture Business Laboratory, Nagoya University, Nagoya (Japan); Ikeda, Mitsuhisa [Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-hiroshima (Japan); Miyazaki, Seiichi [Graduate School of Engineering, Nagoya University, Nagoya (Japan)

    2016-03-01

    We have fabricated two-tiered hetero-structures consisting of B δ-doped and P δ-doped Si quantum dots (QDs) embedded in SiO{sub 2} on p- and n-Si(100) by repeating Si-QDs formation by low pressure chemical vapor deposition (LPCVD) using pure SiH{sub 4} and subsequent surface oxidation and modification by remote plasma, and characterized their electroluminescence (EL) in near-infrared region under DC and AC bias applications to semitransparent Au top-electrodes. The observed EL spectra can be deconvoluted into mainly two components peaked at ~ 1.07 and ~ 1.11 eV, which involve recombination processes through impurity levels. The input power dependence of EL intensities shows that two-tiered structure of P-doped and B-doped Si-QDs is effective to improve EL efficiency while a simple stacking of B-doped Si-QDs is suited to low power operation. This indicates that energy relaxation to lowest quantized levels in charge transfer among valency controlled Si-QDs by impurity doping plays a role on recombination of injected electrons and holes. - Highlights: • We have fabricated two-tiered heterostructures consisting of δ-doped Si-quantum-dots. • The PN junction-like Si-quantum-dots stack is effective to realize high efficient EL. • A simple stacking of B-doped Si-quantum-dots is better suited to low power operation.

  10. Modern ab initio valence bond theory calculations reveal charge shift bonding in protic ionic liquids.

    Science.gov (United States)

    Patil, Amol Baliram; Bhanage, Bhalchandra Mahadeo

    2016-06-21

    The nature of bonding interactions between the cation and the anion of an ionic liquid is at the heart of understanding ionic liquid properties. A particularly interesting case is a special class of ionic liquids known as protic ionic liquids. The extent of proton transfer in protic ionic liquids has been observed to vary according to the interacting species. Back proton transfer renders protic ionic liquids volatile and to be considered as inferior ionic liquids. We try to address this issue by employing modern ab initio valence bond theory calculations. The results indicate that the bonding in the cation and the anion of a prototypical ionic liquid, ethylammonium nitrate, is fundamentally different. It is neither characteristic of covalent/polar covalent bonding nor ionic bonding but rather charge shift bonding as a resonance hybrid of two competing ionic molecular electronic structure configurations. An investigation of other analogous protic ionic liquids reveals that this charge shift bonding seems to be a typical characteristic of protic ionic liquids while the ionic solid analogue compound ammonium nitrate has less charge shift bonding character as compared to protic ionic liquids. Further the extent of charge shift bonding character has been found to be congruent with the trends in many physicochemical properties such as melting point, conductivity, viscosity, and ionicity of the studied ionic liquids indicating that percentage charge shift character may serve as a key descriptor for large scale computational screening of ionic liquids with desired properties.

  11. Puzzle maker in SmB6: accompany-type valence fluctuation state

    Science.gov (United States)

    Wu, Qi; Sun, Liling

    2017-11-01

    In recent years, studying the Kondo insulator SmB6, a strongly correlated electron material that has been puzzling the community for decades, has again become an attractive topic due to the discovery of its unusual metallic surface state coexisting with the bulk insulating state. Many efforts have been made to understand the microphysics in SmB6, but some puzzles that have been hotly debated and argued have not been solved. In this article, based on the latest progress made in our high-pressure studies on SmB6 and the accumulating results reported by other groups, we propose a notion named the ‘accompany-type valence fluctuation state’, which possibly coexists with the bulk Kondo insulating ground state of SmB6. We expect that this notion could be taken as a common starting point for understanding in a unified way most of the low-temperature phenomena observed by different experimental investigations on SmB6, thus promoting the deciphering of the puzzles. We also expect that this notion could attract rigorous theoretical interpretation and further experimental investigation, or stimulate better thinking on the physics in SmB6.

  12. Positively valenced stimuli facilitate creative novel metaphoric processes by enhancing medial prefrontal cortical activation.

    Science.gov (United States)

    Subramaniam, Karuna; Beeman, Mark; Faust, Miriam; Mashal, Nira

    2013-01-01

    A metaphor is a figure of speech in which a subject is symbolic of another unrelated object. In the present study, we examined neural patterns associated with both novel unfamiliar and conventional familiar metaphoric processing, and how these patterns are modulated by affective valence. Prior to fMRI scanning, participants received a list of word pairs (novel unfamiliar metaphors as well as conventional familiar metaphors) and were asked to denote the valence (positive, negative, or neutral) of each word pair. During scanning, participants had to decide whether the word pairs formed meaningful or meaningless expressions. Results indicate that participants were faster and more accurate at deciding that positively valenced metaphors were meaningful compared to neutral metaphors. These behavioral findings were accompanied by increased activation in the medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), and the right inferior parietal lobe (RIPL). Specifically, positively valenced novel unfamiliar metaphors elicited activation in these brain regions in addition to the left superior temporal gyrus when compared to neutral novel metaphors. We also found that the mPFC and PCC mediated the processing of positively valenced metaphors when compared to negatively valenced metaphors. Positively valenced conventional metaphors, however, elicited different neural signatures when contrasted with either neutral or negatively valenced conventional metaphors. Together, our results indicate that positively valenced stimuli facilitate creative metaphoric processes (specifically novel metaphoric processes) by mediating attention and cognitive control processes required for the access, integration, and selection of semantic associations via modulation of the mPFC. The present study is important for the development of neural accounts of emotion-cognition interactions required for creativity, language, and successful social functioning in general.

  13. First determination of the valence band dispersion of CH3NH3PbI3 hybrid organic-inorganic perovskite

    Science.gov (United States)

    Lee, Min-I.; Barragán, Ana; Nair, Maya N.; Jacques, Vincent L. R.; Le Bolloc'h, David; Fertey, Pierre; Jemli, Khaoula; Lédée, Ferdinand; Trippé-Allard, Gaëlle; Deleporte, Emmanuelle; Taleb-Ibrahimi, Amina; Tejeda, Antonio

    2017-07-01

    The family of hybrid organic-inorganic halide perovskites is in the limelight because of their recently discovered high photovoltaic efficiency. These materials combine photovoltaic energy conversion efficiencies exceeding 22% and low-temperature and low-cost processing in solution; a breakthrough in the panorama of renewable energy. Solar cell operation relies on the excitation of the valence band electrons to the conduction band by solar photons. One factor strongly impacting the absorption efficiency is the band dispersion. The band dispersion has been extensively studied theoretically, but no experimental information was available. Herein, we present the first experimental determination of the valence band dispersion of methylammonium lead halide in the tetragonal phase. Our results pave the way for contrasting the electronic hopping or the electron effective masses in different theories by comparing to our experimental bands. We also show a significant broadening of the electronic states, promoting relaxed conditions for photon absorption, and demonstrate that the tetragonal structure associated to the octahedra network distortion below 50 °C induces only a minor modification of the electronic bands, with respect to the cubic phase at high temperature, thus minimizing the impact of the cubic-tetragonal transition on solar cell efficiencies.

  14. Non-classical behaviour of higher valence dopants in chromium (III) oxide by a Cr vacancy compensation mechanism

    Science.gov (United States)

    Carey, John J.; Nolan, Michael

    2017-10-01

    Modification of metal oxides with dopants that have a stable oxidation in their parent oxides which is higher than the host system is expected to introduce extra electrons into the material to improve carrier mobility. This is essential for applications in catalysis, SOFCs and solar energy materials. Density functional theory calculations are used to investigate the change in electronic and geometric structure of chromium (III) oxide by higher valence dopants, namely; Ce, Ti, V and Zr. For single metal doping, we find that the dopants with variable oxidation states, Ce, Ti and V, adopt a valence state of  +3, while Zr dopant has a  +4 oxidation state and reduces a neighbouring Cr cation. Chromium vacancy formation is greatly enhanced for all dopants, and favoured over oxygen vacancy formation. The Cr vacancies generate holes which oxidise Ce, Ti and V from  +3 to  +4, while also oxidising lattice oxygen sites. For Zr doping, the generated holes oxidise the reduced Cr2+ cation back to Cr3+ and also two lattice oxygen atoms. Three metal atoms in the bulk lattice facilitate spontaneous Cr vacancy from charge compensation. A non-classical compensation mechanism is observed for Ce, Ti and V; all three metals are oxidised from  +3 to  +4, which explains experimental observations that these metals have a  +4 oxidation state in Cr2O3. Charge compensation of the three Zr metals proceeds by a classical higher valence doping mechanism; the three dopants reduce three Cr cations, which are subsequently charge compensated by a Cr vacancy oxidising three Cr2+ to Cr3+. The compensated structures are the correct ground state electronic structure for these doped systems, and used as a platform to investigate cation/anion vacancy formation. Unlike the single metal doped bulks, preference is now given for oxygen vacancy formation over Cr vacancy formation, indicating that the dopants increase the reducibility of Cr2O3 with Ce doping showing the strongest

  15. Experiencing activation: energetic arousal and tense arousal are not mixtures of valence and activation.

    Science.gov (United States)

    Schimmack, Ulrich; Reisenzein, Rainer

    2002-12-01

    R. E. Thayer (1989) proposed 2 types of activation: energetic arousal (awake-tired) and tense arousal (tense-calm). This view has been challenged by claims that energetic arousal and tense arousal are mixtures of valence and a single activation dimension. The authors present a direct test of this hypothesis by computing the correlation between the residuals of energetic arousal and tense arousal after removing the shared variance with valence. Whereas the valence activation hypothesis predicts a strong positive correlation between the 2 residuals, the authors found that it was not significantly different from 0. This finding reaffirms the view of energetic arousal and tense arousal as 2 distinct types of activation.

  16. Photoion mass spectroscopy and valence photoionization of hypoxanthine, xanthine and caffeine

    Science.gov (United States)

    Feyer, Vitaliy; Plekan, Oksana; Richter, Robert; Coreno, Marcello; Prince, Kevin C.

    2009-03-01

    Photoionization mass spectra of hypoxanthine, xanthine and caffeine were measured using the photoelectron-photoion coincidence technique and noble gas resonance radiation at energies from 8.4 to 21.2 eV for ionization. The fragmentation patterns for these compounds show that hydrogen cyanide is the main neutral loss species at higher photon energies, while photoionization below 16.67 eV led predominantly to the parent ion. The valence photoelectron spectra of this family of molecules were measured over an extended energy range, including the inner C, N and O 2s valence orbitals. The observed ion fragments were related to ionization of the valence orbitals.

  17. Valence state partitioning of V between pyroxene-melt: Effects of pyroxene and melt composition, and direct determination of V valence states by XANES. Application to Martian basalt QUE 94201 composition.

    Science.gov (United States)

    Karner, J. M.; Papike, J. J.; Sutton, S. R.; Shearer, C. K.; Burger, P.; McKay, G.; Le, L.

    2008-08-01

    Experiments on a Martian basalt composition show that Dv augite/melt is greater than Dv pigeonite/melt in samples equilibrated under the same fO2 conditions. This increase is due to the increased availability of elements for coupled substitution with the V3+ or V4+ ions, namely A1 and Na. For this bulk composition, both A1 and Na are higher in concentration in augite compared with pigeonite; therefore more V can enter augite than pigeonite. Direct valence state determination by XANES shows that the V3+ and V4+ are the main V species in the melt at fO2 conditions of IW-1 to IW+3.5, whereas pyroxene grains at IW-1, IW, and IW+1 contain mostly V3+. This confirms the idea that V3+ is more compatible in pyroxene than V4+. The XANES data also indicates that a small percentage of V2+ may exist in melt and pyroxene at IW-1. The similar valence of V in glass and pyroxene at IW-1 suggests that V2+ and V3+ may have similar compatibilities in pyroxene.

  18. Valence state partitioning of V between pyroxene-melt: Effects of pyroxene and melt composition, and direct determination of V valence states by XANES. Application to Martian basalt QUE 94201 composition

    Energy Technology Data Exchange (ETDEWEB)

    Karner, J.M.; Papike, J.J.; Sutton, S.R.; Shearer, C.K.; Burger, P.; McKay, G.; Le, L. (UNM); (NASA, Johnson Space Center); (NASA , Johnson Space Center); (UC)

    2009-01-13

    Experiments on a Martian basalt composition show that D{sub V} augite/melt is greater than D{sub V} pigeonite/melt in samples equilibrated under the same fO{sub 2} conditions. This increase is due to the increased availability of elements for coupled substitution with the V{sup 3+} or V{sup 4+} ions, namely Al and Na. for this bulk composition, both Al and Na are higher in concentration in augite compared with pigeonite; therefore more V can enter augite than pigeonite. Direct valence state determination by XANES shows that the V{sup 3+} and V{sup 4+} are the main V species in the melt at fO{sub 2} conditions of IW-1 to IW+3.5, whereas pyroxene grains at IW-1, IW, and IW+1 contain mostly V{sup 3+}. This confirms the idea that V{sup 3+} is more compatible in pyroxene than V{sup 4+}. The Xanes data also indicates that a small percentage of V{sup 2+} may exist in melt and pyroxene at IW-1. The similar valence of V in glass and pyroxene at IW-1 suggests that V{sup 2+} and V{sup 3+} may have similar compatibilities in pyroxene.

  19. Vertical photoionization of liquid-to-supercritical ammonia: thermal effects on the valence-to-conduction band gap.

    Science.gov (United States)

    Urbanek, Janus; Vöhringer, Peter

    2013-07-25

    We recently reported first femtosecond pump–probe experiments on the geminate recombination dynamics of solvated electrons in fluid ammonia (Urbanek et al., J. Phys. Chem. B 2012, 116, 2223–2233). The electrons were generated through a vertical two-photon ionization at a total energy of 9.3 eV. Here, we present a full Monte Carlo analysis of the time-resolved data to determine the solvated electron’s thermalization distance from the ionization hole, NH(3)(+). The simulations are compared with the experiment over wide thermodynamic conditions to obtain insight into the dependence of the vertical ionization mechanism on the electronic properties of the solvent network. The simulations reveal that the average thermalization distance, , decreases strongly with both increasing temperature, T, and decreasing density, ρ, from 3.2 nm in the cryogenic fluid down to roughly 0.5 nm in the dilute supercritical phase with almost gas-like densities. We combine our results with the current understanding of the T,ρ-dependence of the electronic structure of the liquid phase and discuss in detail the role of thermally induced energy level shifts for the valence-to-conduction band gap. The observed changes of the thermalization distance can be well attributed to a gradual decrease of the excess energy initially imparted on the ejected electron as gas-like conditions are progressively approached.

  20. Electron-phonon relaxation and excited electron distribution in gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Zhukov, V. P. [Institute of Solid State Chemistry, Urals Branch of the Russian Academy of Sciences, Pervomayskaya st. 91, Yekaterinburg (Russian Federation); Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tyuterev, V. G., E-mail: valtyut00@mail.ru [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tomsk State Pedagogical University, Kievskaya st. 60, Tomsk (Russian Federation); Tomsk State University, Lenin st. 36, Tomsk (Russian Federation); Chulkov, E. V. [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tomsk State University, Lenin st. 36, Tomsk (Russian Federation); Departamento de Fisica de Materiales, Facultad de Ciencias Qumicas, UPV/EHU and Centro de Fisica de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, Apdo. 1072, 20080 San Sebastian (Spain); Echenique, P. M. [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Facultad de Ciencias Qumicas, UPV/EHU and Centro de Fisica de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, Apdo. 1072, 20080 San Sebastian (Spain)

    2016-08-28

    We develop a theory of energy relaxation in semiconductors and insulators highly excited by the long-acting external irradiation. We derive the equation for the non-equilibrium distribution function of excited electrons. The solution for this function breaks up into the sum of two contributions. The low-energy contribution is concentrated in a narrow range near the bottom of the conduction band. It has the typical form of a Fermi distribution with an effective temperature and chemical potential. The effective temperature and chemical potential in this low-energy term are determined by the intensity of carriers' generation, the speed of electron-phonon relaxation, rates of inter-band recombination, and electron capture on the defects. In addition, there is a substantial high-energy correction. This high-energy “tail” largely covers the conduction band. The shape of the high-energy “tail” strongly depends on the rate of electron-phonon relaxation but does not depend on the rates of recombination and trapping. We apply the theory to the calculation of a non-equilibrium distribution of electrons in an irradiated GaN. Probabilities of optical excitations from the valence to conduction band and electron-phonon coupling probabilities in GaN were calculated by the density functional perturbation theory. Our calculation of both parts of distribution function in gallium nitride shows that when the speed of the electron-phonon scattering is comparable with the rate of recombination and trapping then the contribution of the non-Fermi “tail” is comparable with that of the low-energy Fermi-like component. So the high-energy contribution can essentially affect the charge transport in the irradiated and highly doped semiconductors.

  1. 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...

  2. Studies on the valence electronic structure of Fe and Ni in Fe Ni ...

    Indian Academy of Sciences (India)

    -to- X-ray intensity ratios of Fe and Ni in pure metals and in FeNi1- alloys ( = 0.20, 0.50, 0.58) exhibiting similar crystalline structure have been measured following excitation by 59.54 keV -rays from a 241Am point source, to understand as to why the properties of permalloy Fe0.2Ni0.8 is distinct from other alloy ...

  3. Electronic properties of magnetically doped nanotubes

    Indian Academy of Sciences (India)

    Effect of doping of carbon nanotubes by magnetic transition metal atoms has been considered in this paper. In the case of semiconducting tubes, it was found that the system has zero magnetization, whereas in metallic tubes the valence electrons of the tube screen the magnetization of the dopants: the coupling to the tube ...

  4. Valence, arousal, and task effects in emotional prosody processing

    Directory of Open Access Journals (Sweden)

    Silke ePaulmann

    2013-06-01

    Full Text Available Previous research suggests that emotional prosody processing is a highly rapid and complex process. In particular, it has been shown that different basic emotions can be differentiated in an early event-related brain potential (ERP component, the P200. Often, the P200 is followed by later long lasting ERPs such as the late positive complex (LPC. The current experiment set out to explore in how far emotionality and arousal can modulate these previously reported ERP components. In addition, we also investigated the influence of task demands (implicit vs. explicit evaluation of stimuli. Participants listened to pseudo-sentences (sentences with no lexical content spoken in six different emotions or in a neutral tone of voice while they either rated the arousal level of the speaker or their own arousal level. Results confirm that different emotional intonations can first be differentiated in the P200 component, reflecting a first emotional encoding of the stimulus possibly including a valence tagging process. A marginal significant arousal effect was also found in this time-window with high arousing stimuli eliciting a stronger P200 than low arousing stimuli. The P200 component was followed by a long lasting positive ERP between 400 and 750 ms. In this late time-window, both emotion and arousal effects were found. No effects of task were observed in either time-window. Taken together, results suggest that emotion relevant details are robustly decoded during early processing and late processing stages while arousal information is only reliably taken into consideration at a later stage of processing.

  5. Coincident two-electron emission from surfaces by low-energy electrons

    Science.gov (United States)

    Gollisch, H.; Meinert, D.; Yi, Xiao; Feder, R.

    1997-04-01

    The simultaneous ejection of two electrons from non-magnetic surfaces due to the collision of incident low-energy electrons with valence electrons is treated in a relativistic distorted-wave Born approximation including exchange. The primary electron and the two emitted electrons are described by quasi-particle multiple scattering states. The valence electron is represented by linear combinations of Bloch waves matched at the surface. Screened Coulomb interaction matrix elements between these four states are evaluated. Numerical results for W(0 0 1) are presented and compared with one-dimensional bulk densities of states. Energy-integrated spectra and general features of the 2 e-distribution are in good agreement with recent experimental data.

  6. Determination of the bulk cobalt valence state of co-perovskites containing surface-adsorbed impurities.

    Science.gov (United States)

    Haas, O; Ludwig, Chr; Wokaun, A

    2006-10-15

    We used thermogravimetric hydrogen reduction and iodometric titration to determine the bulk valence state of cobalt in Co-perovskites containing surface carbonate hydroxide or hydroxyl groups. It could be shown that thermogravimetric hydrogen reduction experiments are very sensitive to volatile surface groups, but due to their volatility, they can be specified and the bulk valence state of cobalt can still be deduced from these experiments. The iodometric titration is less sensitive to small volatile surface impurities, but precaution has to be taken that oxygen or iodine does not escape from the solution during dissolution of the sample. Best results were obtained if the sample was titrated during dissolution in a closed argon floated titration apparatus. We tested the two methods using LaCoO3 perovskite as a sample with a known valence state. Both methods delivered satisfactory results, and the valence state could be determined with an accuracy of better than 1%.

  7. Two Routes to Emotional Memory: Distinct Neural Processes for Valence and Arousal

    National Research Council Canada - National Science Library

    Elizabeth A. Kensinger; Suzanne Corkin; Marcus E. Raichle

    2004-01-01

    ... attributable to arousal. By using functional MRI and behavioral studies, we found that distinct cognitive and neural processes contribute to emotional memory enhancement for arousing information versus valenced, nonarousing information...

  8. Overlap valence quarks on a twisted mass sea. A case study for mixed action lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Drach, Vincent; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Herdoiza, Gregorio [UAM/CSIC Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; UAM/CSIC Univ. Autonoma de Madrid (Spain). Inst. de Fisica Teorica; Collaboration: European Twisted Mass Collaboration

    2012-11-15

    We discuss a Lattice QCD mixed action investigation employing Wilson maximally twisted mass sea and overlap valence fermions. Using four values of the lattice spacing, we demonstrate that the overlap Dirac operator assumes a point-like locality in the continuum limit. We also show that by adopting suitable matching conditions for the sea and valence theories a consistent continuum limit for the pion decay constant and light baryon masses can be obtained. Finally, we confront results for sea-valence mixed meson masses and the valence scalar correlator with corresponding expressions of chiral perturbation theory. This allows us to extract low energy constants of mixed action chiral perturbation which characterize the strength of unitarity violations in our mixed action setup.

  9. A continuous mapping between space and valence with left- and right-handers

    National Research Council Canada - National Science Library

    Freddi, Sébastien; Brouillet, Thibaut; Cretenet, Joël; Heurley, Loïc P; Dru, Vincent

    2016-01-01

    In this research, we examined whether emotional valence could correspond to a continuous lateral bias in space, according to a mental metaphor that establishes the mapping between a concrete domain (space...

  10. Life changes and depressive symptoms: the effects of valence and amount of change

    OpenAIRE

    Bennik, Elise C.; Ormel, Johan; Oldehinkel, Albertine J

    2013-01-01

    Background Only few studies have focused on the effects of positive life changes on depression, and the ones that did demonstrated inconsistent findings. The aim of the present study was to obtain a better understanding of the influence of positive life changes on depressive symptoms by decomposing life changes into a valence and an amount of change component. Methods Using hierarchical multiple regression, we examined the unique effects of valence (pleasantness/unpleasantness) and amount of ...

  11. The sensitivity of the electron transport within bulk zinc-blende gallium nitride to variations in the crystal temperature, the doping concentration, and the non-parabolicity coefficient associated with the lowest energy conduction band valley

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqua, Poppy; O' Leary, Stephen K., E-mail: stephen.oleary@ubc.ca [School of Engineering, The University of British Columbia, 3333 University Way, Kelowna, British Columbia V1V 1V7 (Canada)

    2016-09-07

    Within the framework of a semi-classical three-valley Monte Carlo simulation approach, we analyze the steady-state and transient electron transport that occurs within bulk zinc-blende gallium nitride. In particular, we examine how the steady-state and transient electron transport that occurs within this material changes in response to variations in the crystal temperature, the doping concentration, and the non-parabolicity coefficient associated with the lowest energy conduction band valley. These results are then contrasted with those corresponding to a number of other compound semiconductors of interest.

  12. Observation of the c-f hybridization effect in valence-transition system EuPtP

    Energy Technology Data Exchange (ETDEWEB)

    Anzai, Hiroaki; Ichiki, Katsuya [Graduate School of Engineering, Osaka Prefecture University, Sakai (Japan); Schwier, Eike F.; Iwasawa, Hideaki; Arita, Masashi; Sato, Hitoshi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki [Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima (Japan); Mitsuda, Akihiro; Wada, Hirofumi [Graduate School of Science, Kyushu University, Fukuoka (Japan); Mimura, Kojiro [Graduate School of Engineering, Osaka Prefecture University, Sakai (Japan); Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima (Japan)

    2017-06-15

    We study the electronic structure of EuPtP, which exhibits two first-order valence transitions at T{sub 1} = 247 K and T{sub 2} = 201 K, using angle-resolved photoemission spectroscopy. Below T{sub 2}, we observe an energy gap at the crossing point of the bulk Eu 4f and conduction bands. The shape of band dispersions is described by a hybridization-band picture based on the periodic Anderson model. Our results demonstrate the c-f hybridization effect in the low-temperature phase of EuPtP. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-29

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

  14. The power of emotional valence – From cognitive to affective processes in reading

    Directory of Open Access Journals (Sweden)

    Ulrike eAltmann

    2012-06-01

    Full Text Available The comprehension of stories requires the reader to imagine the cognitive and affective states of the characters. The content of many stories is unpleasant, as they often deal with conflict, disturbance or crisis. Nevertheless, unpleasant stories can be liked and enjoyed. In this fMRI study, we used a parametric approach to examine (1 the capacity of increasing negative valence of story contents to activate the mentalizing network (cognitive and affective theory of mind, ToM, and (2 the neural substrate of liking negatively valenced narratives. A set of 80 short narratives was compiled, ranging from neutral to negative emotional valence. For each story mean rating values on valence and liking were obtained from a group of 32 participants in a prestudy, and later included as parametric regressors in the fMRI analysis. Another group of 24 participants passively read the narratives in a 3 Tesla MRI scanner. Results revealed a stronger engagement of affective ToM-related brain areas with increasingly negative story valence. Stories that were unpleasant, but simulatiously liked, selectively engaged the medial prefrontal cortex (mPFC, which might reflect the moral exploration of the story content. Further analysis showed that the more the mPFC becomes engaged during the reading of negatively valenced stories, the more coactivation can be observed in other brain areas related to the neural processing of affective ToM and empathy.

  15. Distracted by pleasure: Effects of positive versus negative valence on emotional capture under load.

    Science.gov (United States)

    Gupta, Rashmi; Hur, Young-Jin; Lavie, Nilli

    2016-04-01

    We report 3 experiments examining the effects of positive versus negative valence and perceptual load in determining attention capture by irrelevant emotional distractors. Participants performed a letter search task searching for 1 of 2 target letters (X or N) in conditions of either low perceptual load (circular nontarget letters) or high perceptual load (angular nontarget letters that are similar to the target letters). On 25% of the trials an irrelevant emotional distractor was presented at the display center and participants were instructed to ignore it. The distractor stimulus was either positive or negative and was selected from 3 different classes: IAPS pictures of erotica or mutilated bodies (Experiment 1), happy or angry faces (Experiment 2), and faces associated with gain or loss in a prior value-learning phase involving a betting game (Experiment 3). The results showed a consistent pattern of interaction of load and valence across the 3 experiments. Irrelevant emotional distractors produced interference effects on search reaction time (RT) in conditions of low load, with no difference between negative and positive valence. High perceptual load, however, consistently reduced interference from the negative-valence distractors, but had no effect on the positive-valence distractors. As these results were consistently found across 3 different categories of emotional distractors, they suggest the general conclusion that attentional capture by irrelevant emotional distractors depends on both their valence and the level of perceptual load in the task and highlight the special status of distractors associated with pleasure. (c) 2016 APA, all rights reserved).

  16. Valence, arousal, and cognitive control: a voluntary task-switching study.

    Science.gov (United States)

    Demanet, Jelle; Liefooghe, Baptist; Verbruggen, Frederick

    2011-01-01

    The present study focused on the interplay between arousal, valence, and cognitive control. To this end, we investigated how arousal and valence associated with affective stimuli influenced cognitive flexibility when switching between tasks voluntarily. Three hypotheses were tested. First, a valence hypothesis that states that the positive valence of affective stimuli will facilitate both global and task-switching performance because of increased cognitive flexibility. Second, an arousal hypothesis that states that arousal, and not valence, will specifically impair task-switching performance by strengthening the previously executed task-set. Third, an attention hypothesis that states that both cognitive and emotional control ask for limited attentional resources, and predicts that arousal will impair both global and task-switching performance. The results showed that arousal affected task-switching but not global performance, possibly by phasic modulations of the noradrenergic system that reinforces the previously executed task. In addition, positive valence only affected global performance but not task-switching performance, possibly by phasic modulations of dopamine that stimulates the general ability to perform in a multitasking environment.

  17. Transient Impulsive Giant Electronic Raman Redistribution

    CERN Document Server

    Miyabe, S

    2014-01-01

    Resonant Raman excitation by ultrafast vacuum ultraviolet laser pulses is a powerful means to study electron dynamics in molecules, but experiments must contend with linear background ionization: frequencies high enough to reach resonant core-valence transitions will usually ionize all occupied orbitals as well, and the ionization cross sections are usually dominant. Here we show that attosecond pulses can induce a new process, transient impulsive stimulated Raman scattering, which can overwhelm valence ionization. Calculations are performed for atomic sodium, but the principal is valid for many molecular systems. This approach opens the path for high fidelity multidimensional spectroscopy with attosecond pulses.

  18. Intervalence-resonant Raman spectroscopy of strongly coupled mixed-valence cluster dimers of ruthenium.

    Science.gov (United States)

    Rocha, Reginaldo C; Brown, Mac G; Londergan, Casey H; Salsman, J Catherine; Kubiak, Clifford P; Shreve, Andrew P

    2005-10-13

    Resonance Raman spectroelectrochemistry (RR-SEC) at -20 degrees C has been performed on the pyrazine-bridged dimer of mu-oxo-centered trinuclear ruthenium-acetate "clusters"--[(dmap)(CO)(mu-OAc)6(mu3-O)Ru3(mu-L(b))Ru3(mu3-O)(mu-OAc)6(CO)(dmap)]n (where dmap = 4-(dimethylamino)pyridine and L(b) = pyrazine-h4 and pyrazine-d4)-in three oxidation states: n = 0, -1, and -2. In the one-electron reduced, "mixed-valent" state (overall -1 charge and a single odd electron; formal oxidation states [II, II, III]-[III, III, II] on the metal centers), the Raman excitation at 800 nm is resonant with a cluster-to-cluster intervalence charge-transfer (IVCT) band. Under these conditions, scattering enhancement is observed for all four totally symmetric vibrational modes of the bridging pyrazine ligand (nu8a, nu9a, nu1, and nu6a) in the investigated spectral range (100-2000 cm(-1)), and there is no evidence of activity in non-totally symmetric vibrations. Resonantly enhanced Raman peaks related to peripheral pyridyl (dmap) ligand modes and low-frequency features arising from the trigonal Ru3O cluster core and the cluster[Ru]-[N]ligand vibrations were also observed in the spectra of the intermediate-valence (n = -1) cluster dimer. The vibrational assignments and interpretations proposed in this work were reinforced by observation of characteristic isotopic frequency shifts accompanying deuteration of the bridging pyrazine. The results reveal that the fully symmetric (A(g)) vibrational motions of the organic bridge are coupled to the nominally metal cluster-to-metal cluster fast intramolecular electron transfer (ET) and provide validation of the near-delocalized description according to a predicted three-site/three-state (e.g., metal-bridge-metal) vibronic coupling model, in which the important role of the bridging ligand in mediating electronic communication and delocalization between charge centers is explicitly considered. Further compelling evidence supporting an extended five

  19. Relaxation of femtosecond photoexcited electrons in a polar indirect ...

    Indian Academy of Sciences (India)

    toexcited electrons (holes) tend to accumulate at the conduction (valence) band minimum (maximum). The final relaxation step (i.e., electron–hole recombination) involves a relatively slow phonon-assisted radiative interband transition across the indirect gap as shown in figure 1. There is thus a pile up of the hot electrons ...

  20. Electronic structure investigation of oxidized aluminium films with electron momentum spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Guo, X.; Canney, S.; Kheifets, A.S.; Vos, M.; Fang, Z.; Utteridge, S.; McCarthy, I.E. [Flinders Univ. of South Australia, Adelaide, SA (Australia). Electronic Structure of Materials Centre; Weigold, E. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1996-09-01

    Electron momentum spectroscopy (EMS) of (e, 2e) measurements with oxidized aluminium thin films have been performed. Due to the surface sensitive mature of the EMS spectrometer employed the measured (e, 2e) events come from the front oxidized layer as viewed by the electron detectors. The measurements show clearly two major features in the spectral momentum density distribution and they are related to the upper valence band and the lower valence band of aluminum oxide. The first is a `dual parabola` energy-momentum dispersion pattern spanning about 8 eV in the upper valence band. This `dual parabola` pattern has been qualitatively reproduced by a linear muffin-tin orbital (LMTO) calculation on spherically averaged {alpha}-A1{sub 2}O{sub 3} with nearly the same energy span. In the lower valence band, the LMTO calculation indicates a dispersion spanning about 5 eV, and the measured spectral momentum density plot shows a similar `bowl` shape but with less dispersion. The possible causes which blur the dispersion in the lower valence band are discussed. Other features in the spectral momentum density distribution are also discussed and compared with the LMTO calculation. 45 refs., 1 tab., 10 figs.

  1. Moessbauer spectroscopic study on valence-detrapping and trapping of mixed-valence trinuclear iron(III, III, II) fluorine-substituted benzoate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yoichi, E-mail: yocsakai@daido-it.ac.jp; Onaka, Satoru [Daido University (Japan); Takahashi, Masashi [Toho University (Japan); Ogiso, Ryo; Takayama, Tsutomu [Daido University (Japan); Nakamoto, Tadahiro [Toray Research Center (Japan)

    2012-03-15

    Four mixed-valence trinuclear iron(III, III, II) fluorine-substituted benzoate complexes were synthesized; Fe{sub 3}O(C{sub 6}F{sub 5}COO){sub 6}(C{sub 5}H{sub 5}N){sub 3}{center_dot}CH{sub 2}Cl{sub 2} (1), Fe{sub 3}O(C{sub 6}F{sub 5}COO){sub 6}(C{sub 5}H{sub 5}N){sub 3} (2), Fe{sub 3}O(2H-C{sub 6}F{sub 4}COO){sub 6}(C{sub 5}H{sub 5}N){sub 3} (3), and Fe{sub 3}O(4H-C{sub 6}F{sub 4}COO){sub 6}(C{sub 5}H{sub 5}N){sub 3} (4), in which valence-detrapping and trapping phenomena have been investigated by {sup 57}Fe- Moessbauer spectroscopy. The valence state of the three iron ions is trapped at lower temperatures while it is fully detrapped at higher temperatures for 1. Valence detrapping is not observed for 2, 3, and 4 even at room temperature, although Moessbauer spectra for 3 and 4 show complicated temperature dependence.

  2. Transferable Pseudo-Classical Electrons for Aufbau of Atomic Ions

    Science.gov (United States)

    Ekesan, Solen; Kale, Seyit; Herzfeld, Judith

    2014-01-01

    Generalizing the LEWIS reactive force field from electron pairs to single electrons, we present LEWIS• in which explicit valence electrons interact with each other and with nuclear cores via pairwise interactions. The valence electrons are independently mobile particles, following classical equations of motion according to potentials modified from Coulombic as required to capture quantum characteristics. As proof of principle, the aufbau of atomic ions is described for diverse main group elements from the first three rows of the periodic table, using a single potential for interactions between electrons of like spin and another for electrons of unlike spin. The electrons of each spin are found to distribute themselves in a fashion akin to the major lobes of the hybrid atomic orbitals, suggesting a pointillist description of the electron density. The broader validity of the LEWIS• force field is illustrated by predicting the vibrational frequencies of diatomic and triatomic hydrogen species. PMID:24752384

  3. Transferable pseudoclassical electrons for aufbau of atomic ions.

    Science.gov (United States)

    Ekesan, Solen; Kale, Seyit; Herzfeld, Judith

    2014-06-05

    Generalizing the LEWIS reactive force field from electron pairs to single electrons, we present LEWIS• in which explicit valence electrons interact with each other and with nuclear cores via pairwise interactions. The valence electrons are independently mobile particles, following classical equations of motion according to potentials modified from Coulombic as required to capture quantum characteristics. As proof of principle, the aufbau of atomic ions is described for diverse main group elements from the first three rows of the periodic table, using a single potential for interactions between electrons of like spin and another for electrons of unlike spin. The electrons of each spin are found to distribute themselves in a fashion akin to the major lobes of the hybrid atomic orbitals, suggesting a pointillist description of the electron density. The broader validity of the LEWIS• force field is illustrated by predicting the vibrational frequencies of diatomic and triatomic hydrogen species. Copyright © 2014 Wiley Periodicals, Inc.

  4. Approach and Withdrawal Tendencies during Written Word Processing: Effects of Task, Emotional Valence, and Emotional Arousal.

    Science.gov (United States)

    Citron, Francesca M M; Abugaber, David; Herbert, Cornelia

    2015-01-01

    The affective dimensions of emotional valence and emotional arousal affect processing of verbal and pictorial stimuli. Traditional emotional theories assume a linear relationship between these dimensions, with valence determining the direction of a behavior (approach vs. withdrawal) and arousal its intensity or strength. In contrast, according to the valence-arousal conflict theory, both dimensions are interactively related: positive valence and low arousal (PL) are associated with an implicit tendency to approach a stimulus, whereas negative valence and high arousal (NH) are associated with withdrawal. Hence, positive, high-arousal (PH) and negative, low-arousal (NL) stimuli elicit conflicting action tendencies. By extending previous research that used several tasks and methods, the present study investigated whether and how emotional valence and arousal affect subjective approach vs. withdrawal tendencies toward emotional words during two novel tasks. In Study 1, participants had to decide whether they would approach or withdraw from concepts expressed by written words. In Studies 2 and 3 participants had to respond to each word by pressing one of two keys labeled with an arrow pointing upward or downward. Across experiments, positive and negative words, high or low in arousal, were presented. In Study 1 (explicit task), in line with the valence-arousal conflict theory, PH and NL words were responded to more slowly than PL and NH words. In addition, participants decided to approach positive words more often than negative words. In Studies 2 and 3, participants responded faster to positive than negative words, irrespective of their level of arousal. Furthermore, positive words were significantly more often associated with "up" responses than negative words, thus supporting the existence of implicit associations between stimulus valence and response coding (positive is up and negative is down). Hence, in contexts in which participants' spontaneous responses are

  5. Partitioning of photosynthetic electron flow between CO2 and O 2 reduction in a C 3 leaf (Phaseolus vulgaris L.) at different CO 2 concentrations and during drought stress.

    Science.gov (United States)

    Cornic, G; Briantais, J M

    1991-01-01

    Photosystem II chlorophyll fluorescence and leaf net gas exchanges (CO2 and H2O) were measured simultaneously on bean leaves (Phaseolus vulgaris L.) submitted either to different ambient CO2 concentrations or to a drought stress. When leaves are under photorespiratory conditions, a simple fluorescence parameter ΔF/ Fm (B. Genty et al. 1989, Biochem. Biophys. Acta 990, 87-92; ΔF = difference between maximum, Fm, and steady-state fluorescence emissions) allows the calculation of the total rate of photosynthetic electron-transport and the rate of electron transport to O2. These rates are in agreement with the measurements of leaf O2 absorption using (18)O2 and the kinetic properties of ribulose-1,5bisphosphate carboxylase/oxygenase. The fluorescence parameter, ΔF/Fm, showed that the allocation of photosynthetic electrons to O2 was increased during the desiccation of a leaf. Decreasing leaf net CO2 uptake, either by decreasing the ambient CO2 concentration or by dehydrating a leaf, had the same effect on the partitioning of photosynthetic electrons between CO2 and O2 reduction. It is concluded that the decline of net CO2 uptake of a leaf under drought stress is only due, at least for a mild reversible stress (causing at most a leaf water deficit of 35%), to stomatal closure which leads to a decrease in leaf internal CO2 concentration. Since, during the dehydration of a leaf, the calculated internal CO2 concentration remained constant or even increased we conclude that this calculation is misleading under such conditions.

  6. Elevated concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and polybrominated diphenyl ethers in hair from workers at an electronic waste recycling facility in Eastern China

    Energy Technology Data Exchange (ETDEWEB)

    Ma Jing [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509 (United States); Applied Radiation Institute, School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, P.O. Box 144, Shanghai 200444 (China); Cheng Jinping; Wang Wenhua [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Kunisue, Tatsuya [Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509 (United States); Wu Minghong [Applied Radiation Institute, School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, P.O. Box 144, Shanghai 200444 (China); Kannan, Kurunthachalam, E-mail: kkannan@wadsworth.org [Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509 (United States); International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China)

    2011-02-28

    Hair samples collected from e-waste recycling workers (n = 23 males, n = 4 females) were analyzed to assess occupational exposures to polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) at a large e-waste recycling facility in Taizhou, eastern China. Hair samples from a reference population composed of residents of Shanghai (n = 11) were analyzed for comparison. The mean concentration of {Sigma}PBDEs (range, 22.8-1020 ng/g dw; mean, 157 ng/g dw) found in hair samples from e-waste recycling workers was approximately 3 times higher than the mean determined for the reference samples. The congener profiles of PBDEs in hair from e-waste recycling workers were dominated by BDE 209, whereas the profiles in the reference-population samples showed comparable levels of BDE 47 and BDE 209. Total PCDD/F concentrations in hair from e-waste workers (range, 126-5820 pg/g dw; mean, 1670 pg/g dw) were approximately 18-fold greater than the concentrations measured in hair from the reference population. Concentrations of PCDFs were greater than concentrations of PCDDs, in all of the hair samples analyzed (samples from e-waste and non-e-waste sites). Tetrachlorodibenzofurans (TCDFs) were the major homologues in hair samples. Overall, e-waste recycling workers had elevated concentrations of both PBDEs and PCDD/Fs, indicating that they are exposed to high levels of multiple persistent organic pollutants.

  7. Control of residual carbon concentration in GaN high electron mobility transistor and realization of high-resistance GaN grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    He, X.G. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Liu, Z.S.; Chen, P.; Le, L.C.; Yang, J.; Li, X.J. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhang, S.M.; Zhu, J.J.; Wang, H.; Yang, H. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2014-08-01

    GaN films were grown by metal-organic chemical vapor deposition (MOCVD) under various growth conditions. The influences of MOCVD growth parameters, i.e., growth pressure, ammonia (NH{sub 3}) flux, growth temperature, trimethyl-gallium flux and H{sub 2} flux, on residual carbon concentration ([C]) were systematically investigated. Secondary ion mass spectroscopy measurements show that [C] can be effectively modulated by growth conditions. Especially, it can increase by reducing growth pressure up to two orders of magnitude. High-resistance (HR) GaN epilayer with a resistivity over 1.0 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. The mechanism of the formation of HR GaN epilayer is discussed. An Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistor structure with a HR GaN buffer layer and an additional low-carbon GaN channel layer is presented, exhibiting a high two dimensional electron gas mobility of 1815 cm{sup 2}/Vs. - Highlights: • Influence of MOCVD parameters on residual carbon concentration in GaN is studied. • GaN layer with a resistivity over 1 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. • High electron mobility transistor (HEMT) structures were prepared. • Control of residual carbon content results in HEMT with high 2-D electron gas mobility.

  8. Structural and Electronic Investigations of Complex Intermetallic Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Hyunjin [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    In solid state chemistry, numerous investigations have been attempted to address the relationships between chemical structure and physical properties. Such questions include: (1) How can we understand the driving forces of the atomic arrangements in complex solids that exhibit interesting chemical and physical properties? (2) How do different elements distribute themselves in a solid-state structure? (3) Can we develop a chemical understanding to predict the effects of valence electron concentration on the structures and magnetic ordering of systems by both experimental and theoretical means? Although these issues are relevant to various compound classes, intermetallic compounds are especially interesting and well suited for a joint experimental and theoretical effort. For intermetallic compounds, the questions listed above are difficult to answer since many of the constituent atoms simply do not crystallize in the same manner as in their separate, elemental structures. Also, theoretical studies suggest that the energy differences between various structural alternatives are small. For example, Al and Ga both belong in the same group on the Periodic Table of Elements and share many similar chemical properties. Al crystallizes in the fcc lattice with 4 atoms per unit cell and Ga crystallizes in an orthorhombic unit cell lattice with 8 atoms per unit cell, which are both fairly simple structures (Figure 1). However, when combined with Mn, which itself has a very complex cubic crystal structure with 58 atoms per unit cell, the resulting intermetallic compounds crystallize in a completely different fashion. At the 1:1 stoichiometry, MnAl forms a very simple tetragonal lattice with two atoms per primitive unit cell, while MnGa crystallizes in a complicated rhombohedral unit cell with 26 atoms within the primitive unit cell. The mechanisms influencing the arrangements of atoms in numerous crystal structures have been studied theoretically by calculating electronic

  9. Bidirectional switch of the valence associated with a hippocampal contextual memory engram.

    Science.gov (United States)

    Redondo, Roger L; Kim, Joshua; Arons, Autumn L; Ramirez, Steve; Liu, Xu; Tonegawa, Susumu

    2014-09-18

    The valence of memories is malleable because of their intrinsic reconstructive property. This property of memory has been used clinically to treat maladaptive behaviours. However, the neuronal mechanisms and brain circuits that enable the switching of the valence of memories remain largely unknown. Here we investigated these mechanisms by applying the recently developed memory engram cell- manipulation technique. We labelled with channelrhodopsin-2 (ChR2) a population of cells in either the dorsal dentate gyrus (DG) of the hippocampus or the basolateral complex of the amygdala (BLA) that were specifically activated during contextual fear or reward conditioning. Both groups of fear-conditioned mice displayed aversive light-dependent responses in an optogenetic place avoidance test, whereas both DG- and BLA-labelled mice that underwent reward conditioning exhibited an appetitive response in an optogenetic place preference test. Next, in an attempt to reverse the valence of memory within a subject, mice whose DG or BLA engram had initially been labelled by contextual fear or reward conditioning were subjected to a second conditioning of the opposite valence while their original DG or BLA engram was reactivated by blue light. Subsequent optogenetic place avoidance and preference tests revealed that although the DG-engram group displayed a response indicating a switch of the memory valence, the BLA-engram group did not. This switch was also evident at the cellular level by a change in functional connectivity between DG engram-bearing cells and BLA engram-bearing cells. Thus, we found that in the DG, the neurons carrying the memory engram of a given neutral context have plasticity such that the valence of a conditioned response evoked by their reactivation can be reversed by re-associating this contextual memory engram with a new unconditioned stimulus of an opposite valence. Our present work provides new insight into the functional neural circuits underlying the

  10. Memory effects of sleep, emotional valence, arousal and novelty in children.

    Science.gov (United States)

    Vermeulen, Marije C M; van der Heijden, Kristiaan B; Benjamins, Jeroen S; Swaab, Hanna; van Someren, Eus J W

    2017-06-01

    Effectiveness of memory consolidation is determined by multiple factors, including sleep after learning, emotional valence, arousal and novelty. Few studies investigated how the effect of sleep compares with (and interacts with) these other factors, of which virtually none are in children. The present study did so by repeated assessment of declarative memory in 386 children (45% boys) aged 9-11 years through an online word-pair task. Children were randomly assigned to either a morning or evening learning session of 30 unrelated word-pairs with positive, neutral or negative valenced cues and neutral targets. After immediately assessing baseline recognition, delayed recognition was recorded either 12 or 24 h later, resulting in four different assessment schedules. One week later, the procedure was repeated with exactly the same word-pairs to evaluate whether effects differed for relearning versus original novel learning. Mixed-effect logistic regression models were used to evaluate how the probability of correct recognition was affected by sleep, valence, arousal, novelty and their interactions. Both immediate and delayed recognition were worse for pairs with negatively valenced or less arousing cue words. Relearning improved immediate and delayed word-pair recognition. In contrast to these effects, sleep did not affect recognition, nor did sleep moderate the effects of arousal, valence and novelty. The findings suggest a robust inclination of children to specifically forget the pairing of words to negatively valenced cue words. In agreement with a recent meta-analysis, children seem to depend less on sleep for the consolidation of information than has been reported for adults, irrespective of the emotional valence, arousal and novelty of word-pairs. © 2017 European Sleep Research Society.

  11. Bidirectional switch of the valence associated with a hippocampal contextual memory engram

    Science.gov (United States)

    Redondo, Roger L; Kim, Joshua; Arons, Autumn L; Ramirez, Steve; Liu, Xu; Tonegawa, Susumu

    2014-01-01

    The valence of memories is malleable because of their intrinsic reconstructive property1. This property of memory has been used clinically to treat maladaptive behaviours2. However, the neuronal mechanisms and brain circuits that enable the switching of the valence of memories remain largely unknown. Here, we investigated these mechanisms by applying the recently developed memory engram cell-labelling and -manipulation technique 3,4. We labelled, with Channelrhodopsin-2 (ChR2), a population of cells in either the dorsal dentate gyrus (DG) of the hippocampus or the basolateral complex of the amygdala (BLA) that were specifically activated during contextual fear or reward conditioning. Both groups of fear-conditioned mice displayed aversive light-dependent responses in an optogenetic place avoidance test, whereas both DG- and BLA-labelled mice that underwent reward conditioning exhibited an appetitive response in an optogenetic place preference test. Next, in an attempt to reverse the valence of memory within a subject, mice whose DG or BLA engram had initially been labelled by contextual fear or reward conditioning were subjected to a second conditioning of the opposite valence while their original DG or BLA engram was reactivated by blue light. Subsequent optogenetic place avoidance and preference tests revealed that while the DG-engram group displayed a response indicating a switch of the memory valence, the BLA-engram group did not. This switch was also evident at the cellular level by a change in functional connectivity between DG engram-bearing cells and BLA engram-bearing cells. Thus, we found that in the DG, the neurons carrying the memory engram of a given neutral context have plasticity such that the valence of a conditioned response evoked by their reactivation can be reversed by re-associating this contextual memory engram with a new US of an opposite valence. Our present work provides new insight into the functional neural circuit underlying the

  12. Ab initio study of valence and Rydberg states of CH3Br

    Science.gov (United States)

    Escure, Christelle; Leininger, Thierry; Lepetit, Bruno

    2009-06-01

    We performed configuration interaction ab initio calculations on the valence and 5s, 5pa1, and 5pe Rydberg bands of the CH3Br molecule as a function of the methyl-bromide distance for frozen C3v geometries. The valence state potential energy curves are repulsive, the Rydberg state ones are similar to the one of the CH3Br+ ion with a minimum at short distance. One state emerging from the 5pe band has valence and ion-pair characters as distance increases and the corresponding potential curve has a second minimum at large distance. This state has a very strong parallel electric dipole transition moment with the ground state and plays a central role in UV photon absorption spectra. It is also responsible for the parallel character of the anisotropy parameters measured in ion-pair production experiments. In each band, there is a single state, which has a non-negligible transition moment with the ground state, corresponding to a transition perpendicular to the molecular axis of symmetry, except for the 5pe band where it is parallel. The perpendicular transition moments between ground and valence states increase sharply as methyl-bromide distance decreases due to a mixing between valence and 5s Rydberg band at short distance. In each band, spin orbit interaction produces a pair of states, which have significant transition moments with the ground one. In the valence band, the mixing between singlet and triplet states is weak and the perpendicular transition to the Q11 state is dominant. In each Rydberg band, however, spin-orbit interaction is larger than the exchange interaction and the two significant transition moments with the ground state have comparable strengths. The valence band has an additional state (Q10) with significant parallel transition moment induced by spin-orbit interaction with the ground state at large distance.

  13. Core Levels, Band Alignments, and Valence-Band States in CuSbS 2 for Solar Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Whittles, Thomas J. [Stephenson; Veal, Tim D. [Stephenson; Savory, Christopher N. [Department; Thomas; Welch, Adam W. [Material; de Souza Lucas, Francisco Willian [Material; Gibbon, James T. [Stephenson; Birkett, Max [Stephenson; Potter, Richard J. [Department; Scanlon, David O. [Department; Thomas; Diamond Light Source Ltd., Diamond; Zakutayev, Andriy [Material; Dhanak, Vinod R. [Stephenson

    2017-11-17

    The earth-abundant material CuSbS2 (CAS) has shown good optical properties as a photovoltaic solar absorber material, but has seen relatively poor solar cell performance. To investigate the reason for this anomaly, the core levels of the constituent elements, surface contaminants, ionization potential, and valence-band spectra are studied by X-ray photoemission spectroscopy. The ionization potential and electron affinity for this material (4.98 and 3.43 eV) are lower than those for other common absorbers, including CuInxGa(1-x)Se2 (CIGS). Experimentally corroborated density functional theory (DFT) calculations show that the valence band maximum is raised by the lone pair electrons from the antimony cations contributing additional states when compared with indium or gallium cations in CIGS. The resulting conduction band misalignment with CdS is a reason for the poor performance of cells incorporating a CAS/CdS heterojunction, supporting the idea that using a cell design analogous to CIGS is unhelpful. These findings underline the critical importance of considering the electronic structure when selecting cell architectures that optimize open-circuit voltages and cell efficiencies.

  14. Valence properties of tellurium in different chemical systems and its determination in refractory environmental samples using hydride generation – Atomic fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Wei; Alzahrani, Ali [Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada); Deng, Tian-Long [College of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin (China); Belzile, Nelson, E-mail: nbelzile@laurentian.ca [Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada); Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada)

    2016-01-28

    Using HG – AFS as a powerful tool to study valence transformations of Te, we found that, in presence of HCl and at high temperature, Te can form volatile species and be lost during sample digestion and pre-reduction steps. It was also noticed that the chemical valences of Te can be modified under different chemical and digestion conditions and even by samples themselves with certain matrices. KBr can reduce Te(VI) to Te(IV) in 3.0 M HCl at 100 °C, but when HNO{sub 3} was >5% (v/v) in solution, Br{sub 2} was formed and caused serious interference to Te measurements. HCl alone can also pre-reduce Te(VI) to Te(IV), only when its concentration was ≥6.0 M (100 °C for 15min). Among 10 studied chemical elements, only Cu{sup 2+} caused severe interference. Thiourea is an effective masking agent only when Cu{sup 2+} concentration is equal or lower than 10 mg/L. Chemical reagents, chemical composition of sample, as well as the modes of digestion can greatly affect Te valences, reagent blanks and analytical precisions. A protocol of 2–step–digestion followed by an elimination of HF is proposed to minimize reagent blank and increase the signal/noise ratios. It is important to perform a preliminary test to confirm whether a pre-reduction step is necessary; this is especially true for samples with complex matrices such as those with high sulfide content. The analytical detection limits of this method in a pure solution and a solid sample were 100 ng/L and 0.10 ± 0.02 μg/g, respectively. - Highlights: • HG–AFS is a powerful tool in studies of chemical valences and forms of Te in different conditions. • Te can be lost in form of volatile species in presence of HCl at high temperature. • Metal ions can be classified into 3 categories of interference; thiourea can effectively mask Cu{sup 2+}. • A 2-step digestion allows to eliminate HF, reduce background and improve analytical precision. • Matrix of sample can strongly influence Te chemical valence

  15. Morphology, Spatial Distribution, and Concentration of Flame Retardants in Consumer Products and Environmental Dusts using Scanning Electron Microscopy and Raman Micro-spectroscopy

    OpenAIRE

    Wagner, Jeff; Ghosal, Sutapa; WHITEHEAD, TODD; Metayer, Catherine

    2013-01-01

    We characterized flame retardant (FR) morphologies and spatial distributions in 7 consumer products and 7 environmental dusts to determine their implications for transfer mechanisms, human exposure, and the reproducibility of gas chromatography-mass spectrometry (GC-MS) dust measurements. We characterized individual particles using scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS). Samples were screened for the presence of 3 FR co...

  16. Polarization Dependent Bulk-sensitive Valence Band Photoemission Spectroscopy and Density Functional Theory Calculations: Part I. 3d Transition Metals

    Science.gov (United States)

    Ueda, Shigenori; Hamada, Ikutaro

    2017-12-01

    The X-ray polarization dependent valence band HAXPES spectra of 3d transition metals (TMs) of Ti-Zn were measured to investigate the orbital resolved electronic structures by utilizing that the fact the photoionization cross-section of the atomic orbitals strongly depends on the experimental geometry. We have calculated the HAXPES spectra, which correspond to the cross-section weighted densities of states (CSW-DOSs), where the DOSs were obtained by the density functional theory calculations, and we have determined the relative photoionization cross-sections of the 4s and 4p orbitals to the 3d orbital in the 3d TMs. The experimentally obtained bulk-sensitive 3d and 4s DOSs were good agreement with the calculated DOSs in Ti, V, Cr, and Cu. In contrast, the deviations between the experimental and calculated 3d DOSs for Mn, Fe, Co, Ni were found, suggesting that the electron correlation plays an important role in the electronic structures for these materials.

  17. Synthesis of a Neutral Mixed-Valence Diferrocenyl Carborane for Molecular Quantum-Dot Cellular Automata Applications.

    Science.gov (United States)

    Christie, John A; Forrest, Ryan P; Corcelli, Steven A; Wasio, Natalie A; Quardokus, Rebecca C; Brown, Ryan; Kandel, S Alex; Lu, Yuhui; Lent, Craig S; Henderson, Kenneth W

    2015-12-14

    The preparation of 7-Fc(+) -8-Fc-7,8-nido-[C2 B9 H10 ](-) (Fc(+) FcC2 B9 (-) ) demonstrates the successful incorporation of a carborane cage as an internal counteranion bridging between ferrocene and ferrocenium units. This neutral mixed-valence Fe(II) /Fe(III) complex overcomes the proximal electronic bias imposed by external counterions, a practical limitation in the use of molecular switches. A combination of UV/Vis-NIR spectroscopic and TD-DFT computational studies indicate that electron transfer within Fc(+) FcC2 B9 (-) is achieved through a bridge-mediated mechanism. This electronic framework therefore provides the possibility of an all-neutral null state, a key requirement for the implementation of quantum-dot cellular automata (QCA) molecular computing. The adhesion, ordering, and characterization of Fc(+) FcC2 B9 (-) on Au(111) has been observed by scanning tunneling microscopy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The influence of valence and arousal on reasoning: Affective priming in the semantic verification task

    Directory of Open Access Journals (Sweden)

    Orlić Ana

    2014-01-01

    Full Text Available The aim of the present study was to examine the effects of affective valence and arousal on the reasoning process. Reasoning was measured using a semantic verification task and the influence of valence and arousal was tracked using the affective priming paradigm. Primes were photographs varied on two dimensions - emotional valence (positive, neutral, negative and arousal (high, low. Forty-nine psychology students participated in the experiment. Results showed that reaction time needed for semantic verification was significantly faster for positive-high arousing in comparison to positive-low arousing condition and for neutral high arousing in comparison to neutral-low arousing condition, but there were no significant differences in negative low and high arousing conditions. Also, significant differences were found among all three valences in high arousing conditions and there were no such differences in low arousing conditions. These results reveal the importance of both arousal and valence in the research on the influence of emotions on the reasoning process. [Projekat Ministarstva nauke Republike Srbije, br. 179033

  19. Music, emotion, and time perception: the influence of subjective emotional valence and arousal?

    Science.gov (United States)

    Droit-Volet, Sylvie; Ramos, Danilo; Bueno, José L O; Bigand, Emmanuel

    2013-01-01

    The present study used a temporal bisection task with short (2 s) stimulus durations to investigate the effect on time estimation of several musical parameters associated with emotional changes in affective valence and arousal. In order to manipulate the positive and negative valence of music, Experiments 1 and 2 contrasted the effect of musical structure with pieces played normally and backwards, which were judged to be pleasant and unpleasant, respectively. This effect of valence was combined with a subjective arousal effect by changing the tempo of the musical pieces (fast vs. slow) (Experiment 1) or their instrumentation (orchestral vs. piano pieces). The musical pieces were indeed judged more arousing with a fast than with a slow tempo and with an orchestral than with a piano timbre. In Experiment 3, affective valence was also tested by contrasting the effect of tonal (pleasant) vs. atonal (unpleasant) versions of the same musical pieces. The results showed that the effect of tempo in music, associated with a subjective arousal effect, was the major factor that produced time distortions with time being judged longer for fast than for slow tempi. When the tempo was held constant, no significant effect of timbre on the time judgment was found although the orchestral music was judged to be more arousing than the piano music. Nevertheless, emotional valence did modulate the tempo effect on time perception, the pleasant music being judged shorter than the unpleasant music.

  20. Music, Emotion and Time Perception: The influence of subjective emotional valence and arousal?

    Directory of Open Access Journals (Sweden)

    SYLVIE eDROIT-VOLET

    2013-07-01

    Full Text Available The present study used a temporal bisection task with short (< 2 s and long (> 2 s stimulus durations to investigate the effect on time estimation of several musical parameters associated with emotional changes in affective valence and arousal. In order to manipulate the positive and negative valence of music, Experiments 1 and 2 contrasted the effect of musical structure with pieces played normally and backwards, which were judged to be pleasant and unpleasant, respectively. This effect of valence was combined with a subjective arousal effect by changing the tempo of the musical pieces (fast vs. slow (Experiment 1 or their instrumentation (orchestral vs. piano pieces. The musical pieces were indeed judged more arousing with a fast than with a slow tempo and with an orchestral than with a piano timbre. In Experiment 3, affective valence was also tested by contrasting the effect of tonal (pleasant versus atonal (unpleasant versions of the same musical pieces. The results showed that the effect of tempo in music, associated with a subjective arousal effect, was the major factor that produced time distortions with time being judged longer for fast than for slow tempi. When the tempo was held constant, no significant effect of timbre on the time judgment was found although the orchestral music was judged to be more arousing than the piano music. Nevertheless, emotional valence did modulate the tempo effect on time perception, the pleasant music being judged shorter than the unpleasant music.

  1. Differential Activation of Amygdala Arc Expression By Positive and Negatively Valenced Emotional Learning Conditions

    Directory of Open Access Journals (Sweden)

    Erica eYoung

    2013-12-01

    Full Text Available Norepinephrine is released in the amygdala following negatively arousing learning conditions. This event initiates a cascade of changes including the transcription of activity-regulated cytoskeleton-associated protein (Arc expression, an early-immediate gene associated with memory encoding. Recent evidence suggests that the valence of emotionally laden encounters may generate lateralized, as opposed to symmetric release of this transmitter in the right or left amygdala. It is currently not clear if valence-induced patterns of selective norepinephrine output across hemispheres are also reproduced in downstream pathways of cellular signaling necessary for memory formation. This question was addressed by determining if Arc expression is differentially distributed across the right and left amygdala following exposure to positively or negatively valenced learning conditions respectively. Male Sprague Dawley rats were randomly assigned to groups exposed to the Homecage only, 5 auditory tones only, or 5 auditory tones paired with footshock (0.35mA during Pavlovian fear conditioning. Western blot analysis revealed that Arc expression in the right amygdala was elevated significantly above that observed in the left amygdala 60 and 90 minutes following fear conditioning. Similarly, subjects exposed to a a negatively valenced outcome consisting of an unexpected reduction in food rewards showed a greater level of Arc expression in only the right, but not left basolateral amygdala. Presenting a positively valenced event involving an unexpected increase in food reward magnitude following bar pressing, resulted in significantly greater Arc expression in the left, but not right basolateral amygdala (p

  2. Segregation of information about emotional arousal and valence in horse whinnies.

    Science.gov (United States)

    Briefer, Elodie F; Maigrot, Anne-Laure; Mandel, Roi; Freymond, Sabrina Briefer; Bachmann, Iris; Hillmann, Edna

    2015-04-21

    Studying vocal correlates of emotions is important to provide a better understanding of the evolution of emotion expression through cross-species comparisons. Emotions are composed of two main dimensions: emotional arousal (calm versus excited) and valence (negative versus positive). These two dimensions could be encoded in different vocal parameters (segregation of information) or in the same parameters, inducing a trade-off between cues indicating emotional arousal and valence. We investigated these two hypotheses in horses. We placed horses in five situations eliciting several arousal levels and positive as well as negative valence. Physiological and behavioral measures collected during the tests suggested the presence of different underlying emotions. First, using detailed vocal analyses, we discovered that all whinnies contained two fundamental frequencies ("F0" and "G0"), which were not harmonically related, suggesting biphonation. Second, we found that F0 and the energy spectrum encoded arousal, while G0 and whinny duration encoded valence. Our results show that cues to emotional arousal and valence are segregated in different, relatively independent parameters of horse whinnies. Most of the emotion-related changes to vocalizations that we observed are similar to those observed in humans and other species, suggesting that vocal expression of emotions has been conserved throughout evolution.

  3. Neural systems subserving valence and arousal during the experience of induced emotions.

    Science.gov (United States)

    Colibazzi, Tiziano; Posner, Jonathan; Wang, Zhishun; Gorman, Daniel; Gerber, Andrew; Yu, Shan; Zhu, Hongtu; Kangarlu, Alayar; Duan, Yunsuo; Russell, James A; Peterson, Bradley S

    2010-06-01

    The circumplex model of affect construes all emotions as linear combinations of 2 independent neurophysiological dimensions, valence and arousal. We used functional magnetic resonance imaging to identify the neural networks subserving valence and arousal, and we assessed, in 10 participants, the associations of the BOLD (blood oxygen level-dependent) response, an indirect index of neural activity, with ratings of valence and arousal during the emotional experiences induced by the presentation of evocative sentences. Unpleasant emotional experience was associated with increased BOLD signal intensities in the supplementary motor, anterior midcingulate, right dorsolateral prefrontal, occipito-temporal, inferior parietal, and cerebellar cortices. Highly arousing emotions were associated with increased BOLD signal intensities in the left thalamus, globus pallidus, caudate, parahippocampal gyrus, amygdala, premotor cortex, and cerebellar vermis. Separate analyses using a finite impulse response model confirmed these results and revealed that pleasant emotions engaged an additional network that included the midbrain, ventral striatum, and caudate nucleus, all portions of a reward circuit. These findings suggest the existence of distinct networks subserving the valence and arousal dimensions of emotions, with midline and medial temporal lobe structures mediating arousal and dorsal cortical areas and mesolimbic pathways mediating valence.

  4. Emotional reactivity to valence-loaded stimuli are related to treatment response of neurocognitive therapy.

    Science.gov (United States)

    Vanderhasselt, Marie-Anne; De Raedt, Rudi; Namur, Victoria; Valiengo, Leandro C L; Lotufo, Paulo A; Bensenor, Isabela M; Baeken, Chris; Boggio, Paulo S; Brunoni, Andre R

    2016-01-15

    Emotional Context Insensitivity (ECI) is a psychological feature observed in depressed patients characterized by a decreased emotional reactivity when presented to positive- and negative valence-loaded stimuli. Given that fronto-cingulate-limbic circuits are implicated in abnormal reactivity to valence-loaded stimuli, neurocognitive treatments engaging the prefrontal cortex may be able to modulate this emotional blunting observed in MDD. Therefore, our goal was to evaluate emotional reactivity in depressed patients before and after a combination of neurocognitive interventions that engage the prefrontal cortex (cognitive control training and/or transcranial direct current stimulation). In line with the premises of the ECI framework, before the start of the antidepressant intervention, patients showed blunted emotional reactivity after exposure to negative valence-loaded stimuli. This emotional reactivity pattern changed after 9 sessions of the intervention: positive affect decreased and negative affect increased after watching a series of negative valence-loaded stimuli (i.e. images). Interestingly, higher emotional reactivity (as indexed by a larger increase in negative affect after watching the valence-loaded stimuli) at baseline predicted reductions in depression symptoms after the intervention. On the other hand, higher emotional reactivity (as indexed by a decrease in positive affect) after the intervention was marginally associated with reductions in depression symptoms. To conclude, emotional reactivity increased after the neurocognitive antidepressant intervention and it was directly associated to the degree of depression improvement. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Music, emotion, and time perception: the influence of subjective emotional valence and arousal?

    Science.gov (United States)

    Droit-Volet, Sylvie; Ramos, Danilo; Bueno, José L. O.; Bigand, Emmanuel

    2013-01-01

    The present study used a temporal bisection task with short (2 s) stimulus durations to investigate the effect on time estimation of several musical parameters associated with emotional changes in affective valence and arousal. In order to manipulate the positive and negative valence of music, Experiments 1 and 2 contrasted the effect of musical structure with pieces played normally and backwards, which were judged to be pleasant and unpleasant, respectively. This effect of valence was combined with a subjective arousal effect by changing the tempo of the musical pieces (fast vs. slow) (Experiment 1) or their instrumentation (orchestral vs. piano pieces). The musical pieces were indeed judged more arousing with a fast than with a slow tempo and with an orchestral than with a piano timbre. In Experiment 3, affective valence was also tested by contrasting the effect of tonal (pleasant) vs. atonal (unpleasant) versions of the same musical pieces. The results showed that the effect of tempo in music, associated with a subjective arousal effect, was the major factor that produced time distortions with time being judged longer for fast than for slow tempi. When the tempo was held constant, no significant effect of timbre on the time judgment was found although the orchestral music was judged to be more arousing than the piano music. Nevertheless, emotional valence did modulate the tempo effect on time perception, the pleasant music being judged shorter than the unpleasant music. PMID:23882233

  6. Role of correlated hopping in mixed valence phenomena

    Indian Academy of Sciences (India)

    There are totally 120 basis states and the eigenvectors of H are represented as a lin- ear combination of vectors (4). f-electron density (nf i ) = (1/N). ∑ iσ f. † iσfiσ where N is the number of lattice sites; f–d intersite correlation function cfd = (f† iσdjσ). Low- temperature specific heat is calculated using the relation. C = kBβ. 2 ∂.

  7. Observation of two successive quantum supershells in a 15 000-electron fermionic system

    Energy Technology Data Exchange (ETDEWEB)

    Pellarin, M.; Cottancin, E.; Baguenard, B.; Lerme, J.; Vialle, J.L.; Broyer, M. [Laboratoire de Spectrometrie Ionique et Moleculaire, CNRS Universite Lyon 1, Batiment 205, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France)

    1995-12-15

    The electronic shell structure of gallium clusters has been investigated up to nearly 15 000 valence electrons and two successive supershell nodes are observed. The location of these nodes around 2500 and 7500 electrons, respectively, is interpreted in the framework of the jellium model by introducing the ion pseudopotential and a surface softness for the ionic density.

  8. Emotional Valence, Arousal, and Threat Ratings of 160 Chinese Words among Adolescents.

    Science.gov (United States)

    Ho, Samuel M Y; Mak, Christine W Y; Yeung, Dannii; Duan, Wenjie; Tang, Sandy; Yeung, June C; Ching, Rita

    2015-01-01

    This study was conducted to provide ratings of valence/pleasantness, arousal/excitement, and threat/potential harm for 160 Chinese words. The emotional valence classification (positive, negative, or neutral) of all of the words corresponded to that of the equivalent English language words. More than 90% of the participants, junior high school students aged between 12 and 17 years, understood the words. The participants were from both mainland China and Hong Kong, thus the words can be applied to adolescents familiar with either simplified (e.g. in mainland China) or traditional Chinese (e.g. in Hong Kong) with a junior secondary school education or higher. We also established eight words with negative valence, high threat, and high arousal ratings to facilitate future research, especially on attentional and memory biases among individuals prone to anxiety. Thus, the new emotional word list provides a useful source of information for affective research in the Chinese language.

  9. Name-valence and physical attractiveness in Facebook: their compensatory effects on friendship acceptance.

    Science.gov (United States)

    Greitemeyer, Tobias; Kunz, Irene

    2013-01-01

    Name-valence and physical attractiveness have been shown to be associated with how people respond toward others, in that people judge and behave more positively toward individuals with positive names and individuals who are physically attractive. The present research examined whether Facebook users are more likely to accept friendship requests from other Facebook users with positive (relative to negative) names and who are physically attractive (relative to being moderately attractive). In fact, both name-valence and physical attractiveness affected friendship acceptance. Moreover, results revealed that name-valence can be compensated by physical attractiveness (and vice versa). Acceptance rates of requests from users with positive names who are moderately attractive, as well as requests from users with negative names who are attractive did not significantly differ from those with positive names who are attractive.

  10. fK /f{pi} in Full QCD with Domain Wall Valence Quarks

    Energy Technology Data Exchange (ETDEWEB)

    Silas Beane; Paulo Bedaque; Konstantinos Orginos; Martin Savage

    2007-05-01

    We compute the ratio of pseudoscalar decay constants f{sub K}/f{sub {pi}} using domain-wall valence quarks and rooted improved Kogut-Susskind sea quarks. By employing continuum chiral perturbation theory, we extract the Gasser-Leutwyler low-energy constant L{sub 5}, and extrapolate f{sub K}/f{sub {pi}} to the physical point. We find: f{sub K}/f{sub {pi}} = 1.218 {+-} 0.002{sub -0.024}{sup +0.011} where the first error is statistical and the second error is an estimate of the systematic due to chiral extrapolation and fitting procedures. This value agrees within the uncertainties with the determination by the MILC collaboration, calculated using Kogut-Susskind valence quarks, indicating that systematic errors arising from the choice of lattice valence quark are small.

  11. The role of valence focus and appraisal overlap in emotion differentiation.

    Science.gov (United States)

    Erbas, Yasemin; Ceulemans, Eva; Koval, Peter; Kuppens, Peter

    2015-06-01

    Emotion differentiation refers to the level of specificity with which people distinguish between their emotional states and is considered to play an important role for psychological well-being. Yet, not much is known about what characterizes people high or low in emotion differentiation and what underlies these differences. In 2 studies involving experience sampling (Studies 1-2) and lab based (Study 2) methods, we investigated how emotion differentiation is related to individual differences in valence focus and the overlap in appraisal patterns between emotions. In line with expectations, results showed that high levels of both positive and negative emotion differentiation are related to lower levels of valence focus and lower levels of appraisal overlap between emotions. These findings suggest that individuals who are low in emotion differentiation mainly emphasize the valence aspect of emotions while individuals who are high in emotion differentiation make stronger distinctions between emotions in terms of their underlying appraisal profiles. (c) 2015 APA, all rights reserved).

  12. An X-ray absorption spectroscopic study on mixed conductive La0.6Sr0.4Co0.8Fe0.2O(3-δ) cathodes. I. Electrical conductivity and electronic structure.

    Science.gov (United States)

    Orikasa, Yuki; Ina, Toshiaki; Nakao, Takayuki; Mineshige, Atsushi; Amezawa, Koji; Oishi, Masatsugu; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2011-10-06

    The electrical conduction mechanism of mixed conductive perovskite oxides, La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ), for cathode materials of solid oxide fuel cells has been investigated from electronic structural changes during oxygen vacancy formation. La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ) was annealed under various oxygen partial pressures p(O(2))s at 1073 K and quenched. Iodometric titration indicated that the oxygen nonstoichiometry of La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ) depended on the annealing p(O(2)), with more oxygen vacancies introduced at lower than at higher p(O(2))s. X-Ray absorption spectroscopic measurements were performed at the O K-, Co L-, Fe L-, Co K-, and Fe K-edges. The valence states of the Co and Fe ions were investigated by the X-ray absorption near edge structure (XANES) at the Co and Fe L(III)-edges. While the Fe average valence was almost constant, the valence of the Co ions decreased with oxygen vacancy introduction. The O K-edge XANES spectra indicated that electrons were injected into the Co 3d/O 2p hybridization state with oxygen vacancy introduction. Both absorption edges at the Co and Fe K-edge XANES shifted towards lower energies with oxygen vacancy introduction. The shift at the Co K-edge resulted from the decrease in the Co average valence and that at the Fe K-edge appeared to be caused by changes in the coordination environment around the Fe ions. The total conductivity of La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ) decreased with decreasing p(O(2)), due to a decreasing hole concentration.

  13. Distinct cerebellar lobules process arousal, valence and their interaction in parallel following a temporal hierarchy.

    Science.gov (United States)

    Styliadis, Charis; Ioannides, Andreas A; Bamidis, Panagiotis D; Papadelis, Christos

    2015-04-15

    The cerebellum participates in emotion-related neural circuits formed by different cortical and subcortical areas, which sub-serve arousal and valence. Recent neuroimaging studies have shown a functional specificity of cerebellar lobules in the processing of emotional stimuli. However, little is known about the temporal component of this process. The goal of the current study is to assess the spatiotemporal profile of neural responses within the cerebellum during the processing of arousal and valence. We hypothesized that the excitation and timing of distinct cerebellar lobules is influenced by the emotional content of the stimuli. By using magnetoencephalography, we recorded magnetic fields from twelve healthy human individuals while passively viewing affective pictures rated along arousal and valence. By using a beamformer, we localized gamma-band activity in the cerebellum across time and we related the foci of activity to the anatomical organization of the cerebellum. Successive cerebellar activations were observed within distinct lobules starting ~160ms after the stimuli onset. Arousal was processed within both vermal (VI and VIIIa) and hemispheric (left Crus II) lobules. Valence (left VI) and its interaction (left V and left Crus I) with arousal were processed only within hemispheric lobules. Arousal processing was identified first at early latencies (160ms) and was long-lived (until 980ms). In contrast, the processing of valence and its interaction to arousal was short lived at later stages (420-530ms and 570-640ms respectively). Our findings provide for the first time evidence that distinct cerebellar lobules process arousal, valence, and their interaction in a parallel yet temporally hierarchical manner determined by the emotional content of the stimuli. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Acoustic correlates of emotional dimensions in laughter: arousal, dominance, and valence.

    Science.gov (United States)

    Szameitat, Diana P; Darwin, Chris J; Wildgruber, Dirk; Alter, Kai; Szameitat, Andre J

    2011-06-01

    Although laughter plays an essential part in emotional vocal communication, little is known about the acoustical correlates that encode different emotional dimensions. In this study we examined the acoustical structure of laughter sounds differing along four emotional dimensions: arousal, dominance, sender's valence, and receiver-directed valence. Correlation of 43 acoustic parameters with individual emotional dimensions revealed that each emotional dimension was associated with a number of vocal cues. Common patterns of cues were found with emotional expression in speech, supporting the hypothesis of a common underlying mechanism for the vocal expression of emotions.

  15. Inducing changes in arousal and valence: comparison of two mood induction procedures.

    Science.gov (United States)

    Jallais, Christophe; Gilet, Anne-Laure

    2010-02-01

    This research examined the relative effectiveness of two mood induction procedures (MIPs) for inducing four specific moods varying along the dimensions of both valence and arousal. Participants were randomly assigned either to an autobiographical recall or to a music and guided imagery MIP and underwent a happiness, serenity, anger, or sadness mood induction. The findings confirmed the effectiveness of the two MIPs in producing changes on both the valence and arousal dimensions of mood. The results also revealed an unexpected greater efficiency of the autobiographical recall than of the combined procedure.

  16. Electron Mobility in Polarization-doped Al$\\mathrm{_{0-0.2}}$GaN with a Low Concentration Near 10$\\mathrm{^{17}}$ cm$\\mathrm{^{-3}}$

    OpenAIRE

    Zhu, Mingda; Qi, Meng; Nomoto, Kazuki; Hu, Zongyang; Song, Bo; Pan, Ming; Gao, Xiang; Jena, Debdeep; Xing, Huili Grace

    2017-01-01

    In this letter, carrier transport in graded Al$\\mathrm{_x}$Ga$\\mathrm{_{1-x}}$N with a polarization-induced n-type doping as low as ~ 10$\\mathrm{^{17}}$ cm$\\mathrm{^{-3}}$ is reported. The graded Al$\\mathrm{_x}$Ga$\\mathrm{_{1-x}}$N is grown by metal organic chemical vapor deposition on a sapphire substrate and a uniform n-type doping without any intentional doping is realized by linearly varying the Al composition from 0% to 20% over a thickness of 600 nm. A compensating center concentration ...

  17. Spectroscopic study of Cu{sup 2+} and Cu{sup +} ions in high-transmission glass. Electronic structure and Cu{sup 2+}/Cu{sup +} concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Susana; Rodriguez, Fernando [MALTA-CONSOLIDER-Team, DCITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Urra, Inigo [Departmento Construccion, Area de Energia y medioambiente, CIDEMCO-Tecnalia, 20730 Azpeitia (Spain); Valiente, Rafael, E-mail: gomezss@unican.e [MALTA-CONSOLIDER-Team, Departmento Fisica Aplicada, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain)

    2010-07-28

    This work investigates the formation of photoluminescence centres in high-transmission glass (HTG) doped with Cu{sub 2}O and their capability to transform the solar spectrum by absorption/emission via Stokes-shifted PL into a more efficient spectrum for photovoltaic applications. Among the centres formed in HTG, both green photoluminescent Cu{sup +} and the non-photoluminescent Cu{sup 2+} centres are created but their relative concentration depends on the thermal treatment and the presence of other co-dopants. The measurement of the absorption coefficient {alpha}({lambda}) nearby the HTG optical gap for Cu{sup +} bands is accomplished by following the two-thickness method. This procedure allows us to obtain the actual absorption coefficient for the spectrum of each formed centre, from which we obtain the relative concentration of Cu{sup +}/Cu{sup 2+} as well as their absolute values. The analysis of the spectra provides information on the absorption cross sections, transition energies and bandwidths, the knowledge of which is essential to check the suitability of such centres for photovoltaic applications in solar cells.

  18. Coexistence of magnetic order and valence fluctuations in a heavy fermion system Ce{sub 2}Rh{sub 3}Sn{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Gamza, Monika [Jeremiah Horrocks Institute, University of Central Lancashire, Preston (United Kingdom); MPI CPfS, Dresden (Germany); Institute of Physics, University of Silesia, Katowice (Poland); Gumeniuk, Roman [Institute of Experimental Physics, Freiberg University of Mining and Technology, Freiberg (Germany); MPI CPfS, Dresden (Germany); Schnelle, Walter; Burkhardt, Ulrich; Rosner, Helge [MPI CPfS, Dresden (Germany); Slebarski, Andrzej [Institute of Physics, University of Silesia, Katowice (Poland)

    2016-07-01

    While most Ce-based intermetallics contain either trivalent or intermediate-valent Ce ions, only for a few compounds a coexistence of both species has been reported. Here, we present a combined experimental and theoretical study based on thermodynamic measurements and spectroscopic data together with ab-initio electronic structure calculations aiming at exploring magnetic properties of Ce ions in two nonequivalent sites in Ce{sub 2}Rh{sub 3}Sn{sub 5}. Ce L{sub III} XAS spectra give direct evidence for valence fluctuations. Magnetization measurements show an onset of an antiferromagnetic order at T{sub N}∼2.5 K. The electronic structure calculations suggest that the magnetic ordering is related only to one Ce sublattice. This is in-line with a small entropy associated with the magnetic transition S{sub mag}∼0.35 R ln2 per Ce atom as revealed by the specific heat measurement. Furthermore, the temperature dependence of the magnetic susceptibility can be well described assuming that there are fluctuating moments of Ce{sup 3+} ions in one sublattice, whereas Ce atoms from the second sublattice are in a nonmagnetic intermediate valence state.

  19. Interaction of Cr(3+) with valence and conduction bands in the long persistent phosphor ZnGa2O4:Cr(3+), studied by ENDOR spectroscopy.

    Science.gov (United States)

    Binet, Laurent; Sharma, Suchinder K; Gourier, Didier

    2016-09-28

    Cr(3+)-doped zinc gallate ZnGa2O4 is a red-near infrared (IR) long persistent phosphor that can be excited by orange-red light, in the transparency window of living tissues. With this property, persistent luminescence nanoparticles were recently used for in vivo optical imaging of tumors in mice. In order to understand the origin of the excitability of persistent luminescence by visible light in this material, a Q-band ENDOR investigation of (71/69)Ga and (53)Cr nuclei was performed in ZnGa2O4:Cr(3+) to get information on the interaction of Cr(3+) with valence and conduction bands. The positive electron spin density at Ga nuclei revealed a dominant interaction of the (4)A2 ground state of Cr(3+) with the valence band, and a weaker interaction with the conduction band. The latter may occur only in the excited (2)E and (4)T2 states of Cr(3+). It is proposed that when these two interactions are present, pairs of electrons and holes can be generated from excited Cr(3+) in distorted sites undergoing local electric field produced by neighboring defects with opposite charges.

  20. Interaction of Cr3+ with valence and conduction bands in the long persistent phosphor ZnGa2O4:Cr3+, studied by ENDOR spectroscopy

    Science.gov (United States)

    Binet, Laurent; Sharma, Suchinder K.; Gourier, Didier

    2016-09-01

    Cr3+-doped zinc gallate ZnGa2O4 is a red-near infrared (IR) long persistent phosphor that can be excited by orange-red light, in the transparency window of living tissues. With this property, persistent luminescence nanoparticles were recently used for in vivo optical imaging of tumors in mice. In order to understand the origin of the excitability of persistent luminescence by visible light in this material, a Q-band ENDOR investigation of 71/69Ga and 53Cr nuclei was performed in ZnGa2O4:Cr3+ to get information on the interaction of Cr3+ with valence and conduction bands. The positive electron spin density at Ga nuclei revealed a dominant interaction of the 4A2 ground state of Cr3+ with the valence band, and a weaker interaction with the conduction band. The latter may occur only in the excited 2E and 4T2 states of Cr3+. It is proposed that when these two interactions are present, pairs of electrons and holes can be generated from excited Cr3+ in distorted sites undergoing local electric field produced by neighboring defects with opposite charges.

  1. Valence state control and third-order nonlinear optical properties of copper embedded in sodium borosilicate glass.

    Science.gov (United States)

    Xiang, Weidong; Gao, Haihong; Ma, Li; Ma, Xin; Huang, Yunyun; Pei, Lang; Liang, Xiaojuan

    2015-05-20

    The integrated and transparent sodium borosilicate glasses that contain copper exhibiting different colors, that is, red, green, and blue were synthesized by combining the sol-gel process and heat treatment in H2 gas. To reveal substantially the cause of different colors in the glass, X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution TEM (HRTEM) were systematically applied to investigate and determine the microstructure of the doped matter. The results showed three different crystals had formed in the red, green and blue glass, and the sizes of these crystals were range from 9 to 34, 1 to 6, and 1 to 5 nm, respectively. The valence state of copper was further analyzed by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). The third-order nonlinear optical properties of the glasses were investigated by using Z-scan technique at the wavelength of 800 nm. Interestingly, the third-order nonlinear absorption of the red, green, and blue glass can be successfully controlled from reverse saturable absorption, no absorption to saturable absorption and the optical nonlinear susceptibility χ((3)) of the red, green and blue glass were estimated to be 6.4 × 10(-14), 1.6 × 10(-14), and 2.6 × 10(-14) esu in the single-pulse energy of 0.36 μJ, respectively.

  2. Hard x-ray photoemission study of Yb1-x Zr x B12: the effects of electron doping on the Kondo insulator YbB12

    Science.gov (United States)

    Rousuli, A.; Sato, H.; Iga, F.; Hayashi, K.; Ishii, K.; Wada, T.; Nagasaki, T.; Mimura, K.; Anzai, H.; Ichiki, K.; Ueda, S.; Kondo, A.; Kindo, K.; Takabatake, T.; Shimada, K.; Namatame, H.; Taniguchi, M.

    2017-07-01

    We have carried out hard x-ray photoemission spectroscopy (HAXPES) of Yb1-x Zr x B12 (0≤slant x≤slant 0.875 ) to study the effects of electron doping on the Kondo insulator YbB12. The Yb valences of Yb1-x Zr x B12 at 300 K estimated from the Yb 3d HAXPES spectra decreased after substituting Yb with Zr from 2.93 for YbB12 to 2.83 for Yb0.125Zr0.875B12. A temperature dependent valence decrease was found upon cooling for all doping concentrations. We found peak shifts of the B 1s and Zr 3d5/2, and Yb3+ 4f spectra toward the deeper binding-energy with increasing Zr concentration, which indicates a shift of the Fermi level to the higher energy and that of the Yb 4f hole level close to the Fermi level, respectively, due to electron doping. These results qualitatively show the enhanced hybridization between the Yb 4f and conduction-band states with Zr substitution, consistent with magnetic susceptibility measurements.

  3. Electron-beam-induced current measurements with applied bias provide insight to locally resolved acceptor concentrations at p-n junctions

    Directory of Open Access Journals (Sweden)

    D. Abou-Ras

    2015-07-01

    Full Text Available Electron-beam-induced current (EBIC measurements have been employed for the investigation of the local electrical properties existing at various types of electrical junctions during the past decades. In the standard configuration, the device under investigation is analyzed under short-circuit conditions. Further insight into the function of the electrical junction can be obtained when applying a bias voltage. The present work gives insight into how EBIC measurements at applied bias can be conducted at the submicrometer level, at the example of CuInSe2 solar cells. From the EBIC profiles acquired across ZnO/CdS/CuInSe2/Mo stacks exhibiting p-n junctions with different net doping densities in the CuInSe2 layers, values for the width of the space-charge region, w, were extracted. For all net doping densities, these values decreased with increasing applied voltage. Assuming a linear relationship between w2 and the applied voltage, the resulting net doping densities agreed well with the ones obtained by means of capacitance-voltage measurements.

  4. Electronic Tongue Response to Chemicals in Orange Juice that Change Concentration in Relation to Harvest Maturity and Citrus Greening or Huanglongbing (HLB) Disease.

    Science.gov (United States)

    Raithore, Smita; Bai, Jinhe; Plotto, Anne; Manthey, John; Irey, Mike; Baldwin, Elizabeth

    2015-12-02

    In an earlier study, an electronic tongue system (e-tongue) has been used to differentiate between orange juice made from healthy fruit and from fruit affected by the citrus greening or Huanglongbing (HLB) disease. This study investigated the reaction of an e-tongue system to the main chemicals in orange juice that impact flavor and health benefits and are also impacted by HLB. Orange juice was spiked with sucrose (0.2-5.0 g/100 mL), citric acid (0.1%-3.0% g/100 mL) and potassium chloride (0.1-3.0 g/100 mL) as well as the secondary metabolites nomilin (1-30 µg/mL), limonin (1-30 µg/mL), limonin glucoside (30-200 µg/mL), hesperidin (30-400 µg/mL) and hesperetin (30-400 µg/mL). Performance of Alpha MOS sensor sets #1 (pharmaceutical) and #5 (food) were compared for the same samples, with sensor set #1 generally giving better separation than sensor set #5 for sucrose, sensor set #5 giving better separation for nomilin and limonin, both sets being efficient at separating citric acid, potassium chloride, hesperitin and limonin glucoside, and neither set discriminating hesperidin efficiently. Orange juice made from fruit over the harvest season and from fruit harvested from healthy or HLB-affected trees were separated by harvest maturity, disease state and disease severity.

  5. Electronic Tongue Response to Chemicals in Orange Juice that Change Concentration in Relation to Harvest Maturity and Citrus Greening or Huanglongbing (HLB Disease

    Directory of Open Access Journals (Sweden)

    Smita Raithore

    2015-12-01

    Full Text Available In an earlier study, an electronic tongue system (e-tongue has been used to differentiate between orange juice made from healthy fruit and from fruit affected by the citrus greening or Huanglongbing (HLB disease. This study investigated the reaction of an e-tongue system to the main chemicals in orange juice that impact flavor and health benefits and are also impacted by HLB. Orange juice was spiked with sucrose (0.2–5.0 g/100 mL, citric acid (0.1%–3.0% g/100 mL and potassium chloride (0.1–3.0 g/100 mL as well as the secondary metabolites nomilin (1–30 µg/mL, limonin (1–30 µg/mL, limonin glucoside (30–200 µg/mL, hesperidin (30–400 µg/mL and hesperetin (30–400 µg/mL. Performance of Alpha MOS sensor sets #1 (pharmaceutical and #5 (food were compared for the same samples, with sensor set #1 generally giving better separation than sensor set #5 for sucrose, sensor set #5 giving better separation for nomilin and limonin, both sets being efficient at separating citric acid, potassium chloride, hesperitin and limonin glucoside, and neither set discriminating hesperidin efficiently. Orange juice made from fruit over the harvest season and from fruit harvested from healthy or HLB-affected trees were separated by harvest maturity, disease state and disease severity.

  6. Electronic structure and properties of Cu2O

    OpenAIRE

    Ruiz Sabín, Eliseo; Álvarez, Santiago (Álvarez Reverter); Alemany i Cahner, Pere; Evarestov, R. A. (Robert Aleksandrovich)

    1997-01-01

    The structural and electronic properties of Cu2O have been investigated using the periodic Hartree-Fock method and a posteriori density-functional corrections. The lattice parameter, bulk modulus, and elastic constants have been calculated. The electronic structure of and bonding in Cu2O are analyzed and compared with x-ray photoelectron spectroscopy spectra, showing a good agreement for the valence-band states. To check the quality of the calculated electron density, static structure factors...

  7. Stronger Association Between Valence- and Arousal Ratings of Affective Pictures with Older Age: Evidence for Variation Across Emotion Categories

    DEFF Research Database (Denmark)

    Mikkelsen, Mai Bjørnskov; Mehlsen, Mimi Yung; Lyby, Marlene Skovgaard

    A sample of older and younger adults rated affective pictures according to valence, arousal and emotion category (happiness, sadness and disgust). Results indicate that older age is associated with a stronger linear association between ratings of arousal and valence. Further, the strength...

  8. Intergroup Discrimination in Positive and Negative Outcome Allocations: Impact of Stimulus Valence, Relative Group Status, and Relative Group Size.

    Science.gov (United States)

    Otten, Sabine; And Others

    1996-01-01

    Three studies investigated the determination of social discrimination by the valence of stimuli that are allocated between groups. The studies were based on either the minimal group paradigm or a more reality-based laboratory intergroup setting, with stimulus valence, group status, and group size as factors and with pull scores on Tajfel matrices…

  9. Intergroup discrimination in positive and negative outcome allocations : Impact of stimulus valence, relative group status, and relative group size

    NARCIS (Netherlands)

    Otten, S; Mummendey, A; Blanz, M

    Three studies investigated the determination of social discrimination by the valence of stimuli that are allocated between groups. The studies were based on either the minimal group paradigm or a more reality-based laboratory intergroup setting, with stimulus valence, group status, and group size as

  10. Age-related emotional bias in processing two emotionally valenced tasks.

    Science.gov (United States)

    Allen, Philip A; Lien, Mei-Ching; Jardin, Elliott

    2017-01-01

    Previous studies suggest that older adults process positive emotions more efficiently than negative emotions, whereas younger adults show the reverse effect. We examined whether this age-related difference in emotional bias still occurs when attention is engaged in two emotional tasks. We used a psychological refractory period paradigm and varied the emotional valence of Task 1 and Task 2. In both experiments, Task 1 was emotional face discrimination (happy vs. angry faces) and Task 2 was sound discrimination (laugh, punch, vs. cork pop in Experiment 1 and laugh vs. scream in Experiment 2). The backward emotional correspondence effect for positively and negatively valenced Task 2 on Task 1 was measured. In both experiments, younger adults showed a backward correspondence effect from a negatively valenced Task 2, suggesting parallel processing of negatively valenced stimuli. Older adults showed similar negativity bias in Experiment 2 with a more salient negative sound ("scream" relative to "punch"). These results are consistent with an arousal-bias competition model [Mather and Sutherland (Perspectives in Psychological Sciences 6:114-133, 2011)], suggesting that emotional arousal modulates top-down attentional control settings (emotional regulation) with age.

  11. Zur Besetzung der Leerstellen von Valenztragern (The Occupation of the Empty Spaces of Valence Bearers)

    Science.gov (United States)

    Sommerfeldt, Karl-Ernst

    1973-01-01

    Study of the linguistic means related to the occupation and non-occupation of Leerstellen'' (empty spaces) initiated by semantic and syntactic valence, as in the elliptical usage: Die Henne legt wieder. (Eier)'' (The hen is laying again. YeggsI). (RS)

  12. Memory transfer for emotionally valenced words between identities in dissociative identity disorder

    NARCIS (Netherlands)

    Huntjens, Rafaele J. C.; Peters, Madelon L.; Woertman, Liesbeth; van der Hart, Onno; Postma, Albert

    The present study aimed to determine interidentity retrieval of emotionally valenced words in dissociative identity disorder (DID). Twenty-two DID patients participated together with 25 normal controls and 25 controls instructed to simulate DID. Two wordlists A and B were constructed including

  13. Positive-negative asymmetry in social discrimination : Valence of evaluation and salience of categorization

    NARCIS (Netherlands)

    Mummendey, A; Otten, S; Berger, U; Kessler, T

    2000-01-01

    Several studies have consistently demonstrated a positive-negative asymmetry in intergroup discrimination. As a Possible explanation for this effect, the authors investigated whether stimulus valence has an impact on the salience of social categorization, which, in turn, is assumed to determine the

  14. Emotional cues, emotional signals, and their contrasting effects on listener valence

    DEFF Research Database (Denmark)

    Christensen, Justin

    2015-01-01

    different magnitudes of emotional valence responses between multimodal haptic and audio sources to unimodal audio sources, and whether there are divergences between the different types of emotions presented. Some emotions are more strongly intentional signals (e.g. happiness, fear or grief) while others...

  15. Ueber das Mannheimer Woerterbuch zur Verbvalenz (About the Mannheim Dictionary of Verb Valence)

    Science.gov (United States)

    Schumacher, Helmut

    1976-01-01

    Describes the purpose, structure and application of this monolingual verb lexicon, which indicates the morphosyntactic environments of the most common German verbs. Mention is made of the forthcoming valence lexicon. The book is for teachers and textbook writers. (Text is in German.) (IFS/WGA)

  16. How the social ecology and social situation shape individuals' affect valence and arousal.

    Science.gov (United States)

    Vogel, Nina; Ram, Nilam; Conroy, David E; Pincus, Aaron L; Gerstorf, Denis

    2017-04-01

    Many theories highlight the role social contexts play in shaping affective experience. However, little is known about how individuals' social environments influence core affect on short time-scales (e.g., hours). Using experience sampling data from the iSAHIB, wherein 150 adults aged 18 to 89 years reported on 64,213 social interactions (average 6.92 per day, SD = 2.85) across 9 weeks of daily life, we examined how 4 features of individuals' social ecology (between-person differences) and immediate social situations (within-person changes) were associated with core affect-valence and arousal-and how those associations differ with age. Results from multilevel models revealed that familiarity, importance, type of social partner, and gender composition of the social context were associated with affect valence and/or affect arousal. Higher familiarity, higher importance, and same-gender composition were associated with more positive affect valence and higher arousal. Interactions with family and friends were linked to more positive valence whereas nonfamily social partners were linked to higher arousal. Age moderated the associations between importance and affect arousal, and between type of social partner and both dimensions of core affect. Findings align with theoretical propositions, contributing to but also suggesting need for further precision regarding how development shapes the interplay between social context and moment-to-moment affective experience. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  17. Prévalence et susceptibilité aux antibiotiques des souches de ...

    African Journals Online (AJOL)

    Prévalence et susceptibilité aux antibiotiques des souches de Salmonella spp. non typhiques isolées de la viande de poulets au Tchad. Hamadou Abba, Marius K. Somda, Ban-bo Bebanto Antipas, Nicolas Barro, Alfred S. Traore ...

  18. Type of gesture, valence, and gaze modulate the influence of gestures on observer's behaviors.

    Science.gov (United States)

    De Stefani, Elisa; Innocenti, Alessandro; Secchi, Claudio; Papa, Veronica; Gentilucci, Maurizio

    2013-01-01

    The present kinematic study aimed at determining whether the observation of arm/hand gestures performed by conspecifics affected an action apparently unrelated to the gesture (i.e., reaching-grasping). In 3 experiments we examined the influence of different gestures on action kinematics. We also analyzed the effects of words corresponding in meaning to the gestures, on the same action. In Experiment 1, the type of gesture, valence and actor's gaze were the investigated variables Participants executed the action of reaching-grasping after discriminating whether the gestures produced by a conspecific were meaningful or not. The meaningful gestures were request or symbolic and their valence was positive or negative. They were presented by the conspecific either blindfolded or not. In control Experiment 2 we searched for effects of the sole gaze, and, in Experiment 3, the effects of the same characteristics of words corresponding in meaning to the gestures and visually presented by the conspecific. Type of gesture, valence, and gaze influenced the actual action kinematics; these effects were similar, but not the same as those induced by words. We proposed that the signal activated a response which made the actual action faster for negative valence of gesture, whereas for request signals and available gaze, the response interfered with the actual action more than symbolic signals and not available gaze. Finally, we proposed the existence of a common circuit involved in the comprehension of gestures and words and in the activation of consequent responses to them.

  19. Mixed-valence cytoplasmic iron granules are linked to anaerobic respiration.

    Science.gov (United States)

    Glasauer, S; Langley, S; Boyanov, M; Lai, B; Kemner, K; Beveridge, T J

    2007-02-01

    Intracellular granules containing ferric and ferrous iron formed in Shewanella putrefaciens CN32 during dissimilatory reduction of solid-phase ferric iron. It is the first in situ detection at high resolution (150 nm) of a mixed-valence metal particle residing within a prokaryotic cell. The relationship of the internal particles to Fe(III) reduction may indicate a respiratory role.

  20. Effects of emotional valence and arousal on the voice perception network

    NARCIS (Netherlands)

    Bestelmeyer, Patricia E G; Kotz, Sonja A.; Belin, Pascal

    2017-01-01

    Several theories conceptualise emotions along two main dimensions: valence (a continuum from negative to positive) and arousal (a continuum that varies from low to high). These dimensions are typically treated as independent in many neuroimaging experiments, yet recent behavioural findings suggest

  1. Distinct populations of neurons respond to emotional valence and arousal in the human subthalamic nucleus.

    Science.gov (United States)

    Sieger, Tomáš; Serranová, Tereza; Růžička, Filip; Vostatek, Pavel; Wild, Jiří; Štastná, Daniela; Bonnet, Cecilia; Novák, Daniel; Růžička, Evžen; Urgošík, Dušan; Jech, Robert

    2015-03-10

    Both animal studies and studies using deep brain stimulation in humans have demonstrated the involvement of the subthalamic nucleus (STN) in motivational and emotional processes; however, participation of this nucleus in processing human emotion has not been investigated directly at the single-neuron level. We analyzed the relationship between the neuronal firing from intraoperative microrecordings from the STN during affective picture presentation in patients with Parkinson's disease (PD) and the affective ratings of emotional valence and arousal performed subsequently. We observed that 17% of neurons responded to emotional valence and arousal of visual stimuli according to individual ratings. The activity of some neurons was related to emotional valence, whereas different neurons responded to arousal. In addition, 14% of neurons responded to visual stimuli. Our results suggest the existence of neurons involved in processing or transmission of visual and emotional information in the human STN, and provide evidence of separate processing of the affective dimensions of valence and arousal at the level of single neurons as well.

  2. Memory effects of sleep, emotional valence, arousal and novelty in children

    NARCIS (Netherlands)

    Vermeulen, Marije C M; van der Heijden, Kristiaan B; Benjamins, Jeroen S; Swaab, Hanna; van Someren, Eus J W

    2017-01-01

    Effectiveness of memory consolidation is determined by multiple factors, including sleep after learning, emotional valence, arousal and novelty. Few studies investigated how the effect of sleep compares with (and interacts with) these other factors, of which virtually none are in children. The

  3. The Interaction of Arousal and Valence in Affective Priming: Behavioral and Electrophysiological Evidence

    Science.gov (United States)

    Zhang, Qin; Kong, Lingyue; Jiang, Yang

    2013-01-01

    The affective priming paradigm has been studied extensively and applied in many fields during the past two decades. Most research thus far has focused on the valence dimension. Whether emotional arousal influences affective priming remains poorly understood. The present study demonstrates how arousal impacts evaluation of affective words using reaction time and event-related potential (ERP) measures. Eighteen younger subjects evaluated pleasantness of target words after seeing affective pictures as primes. The participants’ responses were faster and/or more accurate for valence-congruent trials than for incongruent trials, particularly with high-arousal stimuli. An ERP affective priming effect (N400) also occurred mainly in high-arousing stimulus pairs. In addition, whereas valence congruency influenced both the N400 and the LPP, arousal congruency influenced only the LPP, suggesting that arousal congruency mainly modulates post-semantic processes, but valence congruency effects begin with semantic processes. Overall, our current findings indicate that the arousal level of visual images impacts both behavioral and ERP effects of affective priming. Section Cognitive and Behavioral Neuroscience PMID:22820299

  4. Alteration of Expected Hemispheric Asymmetries: Valence and Arousal Effects in Neuropsychological Models of Emotion

    Science.gov (United States)

    Alfano, Keith M.; Cimino, Cynthia R.

    2008-01-01

    The relative advantage of the left (LH) over the right hemisphere (RH) in processing of verbal material for most individuals is well established. Nevertheless, several studies have reported the ability of positively and negatively valenced stimuli to enhance and reverse, respectively, the usual LH greater than RH asymmetry. These studies, however,…

  5. Prévalence des dyslipidémies au laboratoire de biochimie du CHU ...

    African Journals Online (AJOL)

    Prévalence des dyslipidémies au laboratoire de biochimie du CHU Aristide le Dantec de Dakar, Sénégal. Fatou Cissé, Fatou Diallo Agne, Alassane Diatta, Abdou Salam Mbengue, Arame Ndiaye, Abdourahmane Samba, Souleymane Thiam, Dominique Doupa, Gaston Ndéné Sarr, Niama Diop Sall, Méissa Touré ...

  6. Unconscious Processing of Facial Emotional Valence Relation: Behavioral Evidence of Integration between Subliminally Perceived Stimuli.

    Directory of Open Access Journals (Sweden)

    Chengzhen Liu

    Full Text Available Although a few studies have investigated the integration between some types of unconscious stimuli, no research has yet explored the integration between unconscious emotional stimuli. This study was designed to provide behavioral evidence for the integration between unconsciously perceived emotional faces (same or different valence relation using a modified priming paradigm. In two experiments, participants were asked to decide whether two faces in the target, which followed two subliminally presented faces of same or different emotional expressions, were of the same or different emotional valence. The interstimulus interval (ISI between the prime and the target was manipulated (0, 53, 163 ms. In Experiment 1, prime visibility was assessed post-experiment. In Experiment 2, it was assessed on each trial. Interestingly, in both experiments, unconsciously processed valence relation of the two faces in the prime generated a negative priming effect in the response to the supraliminally presented target, independent of the length of ISI. Further analyses suggested that the negative priming was probably caused by a motor response incongruent relation between the subliminally perceived prime and the supraliminally perceived target. The visual feature incongruent relation across the prime and target was not found to play a role in the negative priming. Because the negative priming was found at short ISI, an attention mechanism as well as a motor inhibition mechanism were proposed in the generation of the negative priming effect. Overall, this study indicated that the subliminal valence relation was processed, and that integration between different unconsciously perceived stimuli could occur.

  7. Unconscious Processing of Facial Emotional Valence Relation: Behavioral Evidence of Integration between Subliminally Perceived Stimuli.

    Science.gov (United States)

    Liu, Chengzhen; Sun, Zhiyi; Jou, Jerwen; Cui, Qian; Zhao, Guang; Qiu, Jiang; Tu, Shen

    2016-01-01

    Although a few studies have investigated the integration between some types of unconscious stimuli, no research has yet explored the integration between unconscious emotional stimuli. This study was designed to provide behavioral evidence for the integration between unconsciously perceived emotional faces (same or different valence relation) using a modified priming paradigm. In two experiments, participants were asked to decide whether two faces in the target, which followed two subliminally presented faces of same or different emotional expressions, were of the same or different emotional valence. The interstimulus interval (ISI) between the prime and the target was manipulated (0, 53, 163 ms). In Experiment 1, prime visibility was assessed post-experiment. In Experiment 2, it was assessed on each trial. Interestingly, in both experiments, unconsciously processed valence relation of the two faces in the prime generated a negative priming effect in the response to the supraliminally presented target, independent of the length of ISI. Further analyses suggested that the negative priming was probably caused by a motor response incongruent relation between the subliminally perceived prime and the supraliminally perceived target. The visual feature incongruent relation across the prime and target was not found to play a role in the negative priming. Because the negative priming was found at short ISI, an attention mechanism as well as a motor inhibition mechanism were proposed in the generation of the negative priming effect. Overall, this study indicated that the subliminal valence relation was processed, and that integration between different unconsciously perceived stimuli could occur.

  8. Size-extensive wave functions for quantum Monte Carlo: A linear scaling generalized valence bond approach

    NARCIS (Netherlands)

    Fracchia, F.; Filippi, Claudia; Amovilli, C.

    2012-01-01

    We propose a new class of multideterminantal Jastrow–Slater wave functions constructed with localized orbitals and designed to describe complex potential energy surfaces of molecular systems for use in quantum Monte Carlo (QMC). Inspired by the generalized valence bond formalism, we elaborate a

  9. Las colecciones del Museu Valencià d’Història Natural

    Directory of Open Access Journals (Sweden)

    Martínez-Ortí, A.

    2017-11-01

    Full Text Available The collections of the Museu Valencià d’Història Natural The records of database collections of the Museu Valencia d’Història Natural are published, with a clear dominance of mollusks, arthropods and chordates. Data published through GBIF (doi:10.15470/8oedep.

  10. Affective modulation of response timing in ADHD: The impact of reinforcement valence and magnitude

    NARCIS (Netherlands)

    Luman, M.; Oosterlaan, J.; Sergeant, J.A.

    2008-01-01

    The present study investigated the impact of reinforcement valence and magnitude on response timing in children with ADHD. Children were required to estimate a 1-s interval, and both the median response time (response tendency) and the intrasubject-variability (response stability) were investigated.

  11. Modulation of response timing in ADHD, effects of reinforcement valence magnitude

    NARCIS (Netherlands)

    Luman, M.; Oosterlaan, J.; Sergeant, J.A.

    2008-01-01

    The present study investigated the impact of reinforcement valence and magnitude on response timing in children with ADHD. Children were required to estimate a 1-s interval, and both the median response time (response tendency) and the intrasubject-variability (response stability) were investigated.

  12. Modulation of Response Timing in ADHD, Effects of Reinforcement Valence and Magnitude

    Science.gov (United States)

    Luman, Marjolein; Oosterlaan, Jaap; Sergeant, Joseph A.

    2008-01-01

    The present study investigated the impact of reinforcement valence and magnitude on response timing in children with ADHD. Children were required to estimate a 1-s interval, and both the median response time (response tendency) and the intrasubject-variability (response stability) were investigated. In addition, heart rate and skin conductance…

  13. Of Caucasians, Asians, and Giraffes: The Influence of Categorization and Target Valence on Social Projection.

    Science.gov (United States)

    Machunsky, Maya; Walther, Eva

    2015-09-01

    Past research has indicated that social projection is moderated by categorization, with more projection onto ingroups than onto outgroups. However, a few studies have reported elevated levels of projection even onto outgroups. In line with recent evidence, we hypothesized that positive target valence is the key feature of conditions that elicit projection onto outgroups. The present research extends previous findings by testing whether the effect of valence occurs independent of categorization, with increased levels of projection onto positive ingroup and non-ingroup targets alike. We designed two experiments in which target valence was manipulated by means of evaluative conditioning. Category membership was varied by using faces of Caucasians, Asians, and giraffes. The results supported our valence hypothesis. Counter-intuitively, we also found higher levels of projection onto giraffes than onto humans. These findings suggest that current cognition-based models of projection are not sufficient to account for the whole range of projection phenomena. © 2015 by the Society for Personality and Social Psychology, Inc.

  14. Variations in Group Process Due to Valence, Response Mode, and Directness of Feedback.

    Science.gov (United States)

    Rotheram, Mary; And Others

    1982-01-01

    Evaluated differences in group cohesion, trust, attraction, and perceptions of feedback due to interpersonal feedback. Undergraduate groups experienced intimacy-building exercises and then exchanged varied interpersonal feedback. Results indicated response mode did not affect feedback ratings or cohesion ratings; the valence of the feedback…

  15. THE VALENCE OF AU IN AUTE2 AND AUSE STUDIED BY X-RAY-ABSORPTION SPECTROSCOPY

    NARCIS (Netherlands)

    ETTEMA, ARHF; STEGINK, TA; HAAS, C

    The gold compounds AuTe2 and AuSe contain Au atoms in two different chemical surroundings. In the literature these different coordinations have been associated with a difference in valency of the Au atoms. In this paper the occupation of the 5d shell in AuSe and AuTe2 is deduced from a study of the

  16. A General Valence Asymmetry in Similarity: Good Is More Alike than Bad

    Science.gov (United States)

    Koch, Alex; Alves, Hans; Krüger, Tobias; Unkelbach, Christian

    2016-01-01

    The density hypothesis (Unkelbach, Fiedler, Bayer, Stegmüller, & Danner, 2008) claims a general higher similarity of positive information to other positive information compared with the similarity of negative information to other negative information. This similarity asymmetry might explain valence asymmetries on all levels of cognitive…

  17. The Effect of an Extinction Cue on ABA-Renewal: Does Valence Matter?

    Science.gov (United States)

    Dibbets, Pauline; Maes, Joseph H. R.

    2011-01-01

    The present human fear conditioning study examined whether the valence of an extinction cue has a differential effect on attenuating renewal that is induced by removal of the extinction context. Additionally, the study aimed to assess whether such attenuating effect is based on a modulatory or safety-signal role of the cue. In acquisition,…

  18. The effect of an extinction cue on ABA-renewal: Does valence matter?

    NARCIS (Netherlands)

    Dibbets, P.; Maes, J.H.R.

    2011-01-01

    The present human fear conditioning study examined whether the valence of an extinction cue has a differential effect on attenuating renewal that is induced by removal of the extinction context. Additionally, the study aimed to assess whether such attenuating effect is based on a modulatory or

  19. Talking about alcohol consumption: health campaigns, conversational valence, and binge drinking intentions

    NARCIS (Netherlands)

    Hendriks, H.; de Bruijn, G.-J.; van den Putte, B.

    2012-01-01

    Objectives. Although research has shown that whether people talk about health issues influences health campaign effects, no evidence exists on whether conversational valence fulfils a mediating role within health campaign effects. In the context of alcohol consumption, this two-wave experimental

  20. Subjective reality: the influence of perceived and objective conversational valence on binge drinking determinants

    NARCIS (Netherlands)

    Hendriks, H.; van den Putte, B.; de Bruijn, G.J.

    2015-01-01

    Previous studies have shown that interpersonal communication, and particularly perceived conversational valence (i.e., the perceived negativity or positivity of conversations) about health topics, influences health determinants. On the basis of 43 dyads (N = 86) discussing the topic of alcohol

  1. Cheminoes: A Didactic Game to Learn Chemical Relationships between Valence, Atomic Number, and Symbol

    Science.gov (United States)

    Moreno, Luis F.; Hincapié, Gina; Alzate, María Victoria

    2014-01-01

    Cheminoes is a didactic game that enables the meaningful learning of some relations between concepts such as chemical element, valence, atomic number, and chemical symbol for the first 36 chemical elements of the periodic system. Among the students who have played the game, their opinions of the activity were positive, considering the game to be a…

  2. Spin dynamics of the intermediate-valence compound EuCu2Si2

    NARCIS (Netherlands)

    Alekseev, P. A.; Mignot, J.-M.; Nemkovski, K. S.; Lazukov, V. N.; Nefeodova, E. V.; Menushenkov, A. P.; Kuznetsov, A. V.; Bewley, R. I.; Gribanov, A. V.

    The dynamic magnetic response of the intermediate-valence compound EuCu2Si2 has been studied using inelastic neutron scattering. At low temperatures, strong renormalization of the F-7(0) -> F-7(1) spin-orbit transition energy is detected; it is likely to be related to partial delocalization of the f

  3. Core and Valence Structures in K beta X-ray Emission Spectra of Chromium Materials

    NARCIS (Netherlands)

    Torres Deluigi, Maria; de Groot, Frank M. F.; Lopez-Diaz, Gaston; Tirao, German; Stutz, Guillermo; Riveros de la Vega, Jose

    2014-01-01

    We analyze the core and valence transitions in chromium in a series of materials with a number of different ligands and including the oxidation states: Cr-II, Cr-III, Cr-IV, and Cr-VI. To study the core-to-core transitions we employ the CTM4XAS program and investigate the shapes, widths,

  4. A valence force field-Monte Carlo algorithm for quantum dot growth modeling

    DEFF Research Database (Denmark)

    Barettin, Daniele; Kadkhodazadeh, Shima; Pecchia, Alessandro

    2017-01-01

    We present a novel kinetic Monte Carlo version for the atomistic valence force fields algorithm in order to model a self-assembled quantum dot growth process. We show our atomistic model is both computationally favorable and capture more details compared to traditional kinetic Monte Carlo models...

  5. Brain activations to emotional pictures are differentially associated with valence and arousal ratings

    Directory of Open Access Journals (Sweden)

    Antje B M Gerdes

    2010-10-01

    Full Text Available Several studies have investigated the neural responses triggered by emotional pictures, but the specificity of the involved structures such as the amygdala or the ventral striatum is still under debate. Furthermore, only few studies examined the association of stimuli’s valence and arousal and the underlying brain responses. Therefore, we investigated brain responses with functional magnetic resonance imaging of 17 healthy subjects to pleasant and unpleasant affective pictures with comparable arousal levels and afterwards assessed ratings of valence and arousal. As expected, unpleasant pictures strongly activated the right and left amygdala, the right hippocampus, and the medial occipital lobe, whereas pleasant pictures elicited significant activations in left occipital regions, and in parts of the medial temporal lobe. The direct comparison of unpleasant and pleasant pictures which were comparable in arousal clearly indicated stronger amygdala activation in response to the unpleasant pictures. Most important, correlational analyses revealed on the one hand that the arousal of unpleasant pictures was significantly associated with activations in the right amygdala and the left caudate body. On the other hand, valence of pleasant pictures was significantly correlated with activations in the right caudate head, extending to the nucleus accumbens (NAcc and the left dorso-lateral prefrontal cortex. These findings support the notion that the amygdala is primarily involved in processing of unpleasant stimuli, and the stronger the more arousing the stimuli are, whereas reward-related structures like the NAcc primarily responds to pleasant stimuli, the stronger the more positive the valence of these stimuli is.

  6. Synthesis, Characterization, and Antibacterial Activities of High-Valence Silver Propamidine Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jinran Lee

    2017-07-01

    Full Text Available Diabetic foot ulcer (DFU is becoming more serious concern as it affects 95% of diabetic patients worldwide. It has been shown that the Staphylococcus aureus and other Gram-negative microorganisms are the main reasons behind this disease. Though many antibiotics are presently used to treat the DFU, due to increased bacterial resistance, new alternative therapies are always welcome. To address this alarming issue, we have designed and synthesized the high-valence silver propamidine (Ag(IIPRO complex as well as nanoparticles and characterized both by usual spectroscopic methods. The reverse microemulsion technique has been applied to synthesize Ag(IIPRO nanoparticles and its antibacterial activity has been compared with zero-valence silver nanoparticles (AgNPs with similar size. The antibacterial efficacies of Ag(IIPRO nanoparticles and AgNPs were tested against Gram-negative and Gram -positive organisms responsible for DFU. The newly synthesized high-valence Ag(IIPRO nanoparticles showed higher antibacterial activity compared to silver-only nanoparticles (AgNPs. This study concludes that the high-valence Ag(IIPRO nanoparticles show better antibacterial activity than AgNPs and they may serve as the next generation therapeutic agent for the diabetic wound care.

  7. Two in One Conditioning? The Role of Valence in Concept Learning

    Science.gov (United States)

    Glaser, Tina; Walther, Eva

    2013-01-01

    The present two studies investigated whether semantic as well as evaluative stimulus aspects can be conditioned to neutral stimuli. In Study 1, pictures of large and small objects were paired with neutral stimuli (conditioned stimuli (CSs)). The subsequently assessed size and likeability ratings indicated that valence as well as size was…

  8. DeltaPhage—a novel helper phage for high-valence pIX phagemid display

    Science.gov (United States)

    Nilssen, Nicolay R.; Frigstad, Terje; Pollmann, Sylvie; Roos, Norbert; Bogen, Bjarne; Sandlie, Inger; Løset, Geir Å.

    2012-01-01

    Phage display has been instrumental in discovery of novel binding peptides and folded domains for the past two decades. We recently reported a novel pIX phagemid display system that is characterized by a strong preference for phagemid packaging combined with low display levels, two key features that support highly efficient affinity selection. However, high diversity in selected repertoires are intimately coupled to high display levels during initial selection rounds. To incorporate this additional feature into the pIX display system, we have developed a novel helper phage termed DeltaPhage that allows for high-valence display on pIX. This was obtained by inserting two amber mutations close to the pIX start codon, but after the pVII translational stop, conditionally inactivating the helper phage encoded pIX. Until now, the general notion has been that display on pIX is dependent on wild-type complementation, making high-valence display unachievable. However, we found that DeltaPhage does facilitate high-valence pIX display when used with a non-suppressor host. Here, we report a side-by-side comparison with pIII display, and we find that this novel helper phage complements existing pIX phagemid display systems to allow both low and high-valence display, making pIX display a complete and efficient alternative to existing pIII phagemid display systems. PMID:22539265

  9. Facial and semantic emotional interference: A pilot study on the behavioral and cortical responses to the dual valence association task

    Directory of Open Access Journals (Sweden)

    Petroni Agustín

    2011-04-01

    Full Text Available Abstract Background Integration of compatible or incompatible emotional valence and semantic information is an essential aspect of complex social interactions. A modified version of the Implicit Association Test (IAT called Dual Valence Association Task (DVAT was designed in order to measure conflict resolution processing from compatibility/incompatibly of semantic and facial valence. The DVAT involves two emotional valence evaluative tasks which elicits two forms of emotional compatible/incompatible associations (facial and semantic. Methods Behavioural measures and Event Related Potentials were recorded while participants performed the DVAT. Results Behavioural data showed a robust effect that distinguished compatible/incompatible tasks. The effects of valence and contextual association (between facial and semantic stimuli showed early discrimination in N170 of faces. The LPP component was modulated by the compatibility of the DVAT. Conclusions Results suggest that DVAT is a robust paradigm for studying the emotional interference effect in the processing of simultaneous information from semantic and facial stimuli.

  10. Concentration device

    DEFF Research Database (Denmark)

    2013-01-01

    A concentration device (2) for filter filtration concentration of particles (4) from a volume of a fluid (6). The concentration device (2) comprises a filter (8) configured to filter particles (4) of a predefined size in the volume of the fluid (6). The concentration device (2) comprises...

  11. Isotope effect on electron paramagnetic resonance of boron acceptors in silicon

    Science.gov (United States)

    Stegner, A. R.; Tezuka, H.; Andlauer, T.; Stutzmann, M.; Thewalt, M. L. W.; Brandt, M. S.; Itoh, K. M.

    2010-09-01

    The fourfold degeneracy of the boron acceptor ground state in silicon, which is easily lifted by any symmetry-breaking perturbation, allows for a strong inhomogeneous broadening of the boron-related electron paramagnetic resonance (EPR) lines, e.g., by a random distribution of local strains. However, since EPR of boron acceptors in externally unstrained silicon was reported initially, neither the line shape nor the magnitude of the residual broadening observed in samples with high-crystalline purity were compatible with the low concentrations of carbon and oxygen point defects, being the predominant source of random local strain. Adapting a theoretical model which has been applied to understand the acceptor ground-state splitting in the absence of a magnetic field as an effect due to the presence of different silicon isotopes, we show that local fluctuations of the valence-band edge due to different isotopic configurations in the vicinity of the boron acceptors can quantitatively account for all inhomogeneous broadening effects in high-purity Si with a natural isotope composition. Our calculations show that such an isotopic perturbation also leads to a shift in the g value of different boron-related resonances, which we could verify in our experiments. Further, our results provide an independent test and verification of the valence-band offsets between the different Si isotopes determined in previous works.

  12. Borderline Personality Disorder and Automatic Processing of Valence and Self-Other Relevance Information.

    Science.gov (United States)

    Donges, Uta-Susan; Dukalski, Bibiana; Suslow, Thomas

    Enhanced sensitivity to emotion stimuli and poor differentiation between self and others have been proposed to be important features of borderline personality disorder (BPD). Automatic processing of affective stimuli provides information about valence (positive vs. negative) and relevance of valence (self vs. other). The objectives of our study were to investigate the efficiency of automatic processing of valence and relevance at a semantic level in BPD compared to healthy individuals. A masked affective priming task, varying the valence and relevance of prime and target adjectives, was administered to 33 women with BPD and 33 healthy women. The forward and backward masked primes were shown for 50 ms. Subjects had the task of evaluating target words. In the whole sample, a significant affective priming effect and a significant relevance priming effect occurred. BPD patients did not significantly differ from healthy individuals in affective priming or relevance priming after controlling for age, education, and intelligence. The presence of comorbid somatoform disorders was associated with increased affective priming and reduced relevance priming in BPD patients. The efficiency of automatic recognition and the processing of valence information at a semantic level are not impaired in BPD. Moreover, BPD patients are able to perceive and differentiate automatically self- versus other-relevance during the perception of affective information like healthy controls. Thus, there is no evidence for enhanced sensitivity to emotion stimuli or poor differentiation between self and others in BPD at a very early stage of processing. The presence of somatoform disorders appears to influence affective as well as relevance priming in BPD. © 2016 S. Karger AG, Basel.

  13. Valence of Facial Cues Influences Sheep Learning in a Visual Discrimination Task

    Directory of Open Access Journals (Sweden)

    Lucille G. A. Bellegarde

    2017-11-01

    Full Text Available Sheep are one of the most studied farm species in terms of their ability to process information from faces, but little is known about their face-based emotion recognition abilities. We investigated (a whether sheep could use images of sheep faces taken in situation of varying valence as cues in a simultaneous discrimination task and (b whether the valence of the situation affects their learning performance. To accomplish this, we photographed faces of sheep in three situations inducing emotional states of neutral (ruminating in the home pen or negative valence (social isolation or aggressive interaction. Sheep (n = 35 first had to learn a discrimination task with colored cards. Animals that reached the learning criterion (n = 16 were then presented with pairs of images of the face of a single individual taken in the neutral situation and in one of the negative situations. Finally, sheep had to generalize what they had learned to new pairs of images of faces taken in the same situation, but of a different conspecific. All sheep that learned the discrimination task with colored cards reached the learning criterion with images of faces. Sheep that had to associate a negative image with a food reward learned faster than sheep that had to associate a neutral image with a reward. With the exception of sheep from the aggression-rewarded group, sheep generalized this discrimination to images of faces of different individuals. Our results suggest that sheep can perceive the emotional valence displayed on faces of conspecifics and that this valence affects learning processes.

  14. High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded a-plane sapphire at low temperature

    Science.gov (United States)

    Jayah, Nurul Azzyaty; Yahaya, Hafizal; Mahmood, Mohamad Rusop; Terasako, Tomoaki; Yasui, Kanji; Hashim, Abdul Manaf

    2015-01-01

    Hydrothermal zinc oxide (ZnO) thick films were successfully grown on the chemical vapor deposition (CVD)-grown thick ZnO seed layers on a-plane sapphire substrates using the aqueous solution of zinc nitrate dehydrate (Zn(NO3)2). The use of the CVD ZnO seed layers with the flat surfaces seems to be a key technique for obtaining thick films instead of vertically aligned nanostructures as reported in many literatures. All the hydrothermal ZnO layers showed the large grains with hexagonal end facets and were highly oriented towards the c-axis direction. Photoluminescence (PL) spectra of the hydrothermal layers were composed of the ultraviolet (UV) emission (370 to 380 nm) and the visible emission (481 to 491 nm), and the intensity ratio of the former emission ( I UV) to the latter emission ( I VIS) changed, depending on both the molarity of the solution and temperature. It is surprising that all the Hall mobilities for the hydrothermal ZnO layers were significantly larger than those for their corresponding CVD seed films. It was also found that, for the hydrothermal films grown at 70°C to 90°C, the molarity dependences of I UV/ I VIS resembled those of mobilities, implying that the mobility in the film is affected by the structural defects. The highest mobility of 166 cm2/Vs was achieved on the hydrothermal film with the carrier concentration of 1.65 × 1017 cm-3 grown from the aqueous solution of 40 mM at 70°C.

  15. Investigating Antibacterial Effects of Garlic (Allium sativum) Concentrate and Garlic-Derived Organosulfur Compounds on Campylobacter jejuni by Using Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, and Electron Microscopy ▿ †

    Science.gov (United States)

    Lu, Xiaonan; Rasco, Barbara A.; Jabal, Jamie M. F.; Aston, D. Eric; Lin, Mengshi; Konkel, Michael E.

    2011-01-01

    Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy were used to study the cell injury and inactivation of Campylobacter jejuni from exposure to antioxidants from garlic. C. jejuni was treated with various concentrations of garlic concentrate and garlic-derived organosulfur compounds in growth media and saline at 4, 22, and 35°C. The antimicrobial activities of the diallyl sulfides increased with the number of sulfur atoms (diallyl sulfide garlic, much greater than those of garlic phenolic compounds, as indicated by changes in the spectral features of proteins, lipids, and polysaccharides in the bacterial cell membranes. Confocal Raman microscopy (532-nm-gold-particle substrate) and Raman mapping of a single bacterium confirmed the intracellular uptake of sulfur and phenolic components. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to verify cell damage. Principal-component analysis (PCA), discriminant function analysis (DFA), and soft independent modeling of class analogs (SIMCA) were performed, and results were cross validated to differentiate bacteria based upon the degree of cell injury. Partial least-squares regression (PLSR) was employed to quantify and predict actual numbers of healthy and injured bacterial cells remaining following treatment. PLSR-based loading plots were investigated to further verify the changes in the cell membrane of C. jejuni treated with organosulfur compounds. We demonstrated that bacterial injury and inactivation could be accurately investigated by complementary infrared and Raman spectroscopies using a chemical-based, “whole-organism fingerprint” with the aid of chemometrics and electron microscopy. PMID:21642409

  16. What are the influences of orthogonally-manipulated valence and arousal on performance monitoring processes? The effects of affective state.

    Science.gov (United States)

    Larson, Michael J; Gray, Alexander C; Clayson, Peter E; Jones, Rochelle; Kirwan, C Brock

    2013-03-01

    Studies of the influence of affective state on the cognitive control process of performance monitoring are mixed and few studies have orthogonally manipulated affective valence and arousal. Performance monitoring can be measured using behaviors (e.g., response times and error rates) and components of the event-related potentials (ERPs), such as the error-related negativity (ERN), correct-related negativity (CRN), and post-error positivity (Pe). We used a pre/post design and standard mood induction paradigm in 121 healthy participants randomly assigned to orthogonal valence (positive or negative) and arousal (high or low) conditions (i.e., happy, calm, anxious, or sad mood states). Following mood induction, valence and arousal ratings differed between groups. Behavioral findings showed decreased accuracy in participants with high arousal and negative valence (i.e., anxious condition), but no additional response time (RT), post-error slowing, or accuracy effects. Amplitude of the CRN differentiated high and low valence, but was not related to arousal. Positive valence was associated with decreased CRN amplitude even when baseline affect and demographic variables were controlled. Valence and arousal did not significantly differentiate the amplitude of the ERN, although the ERN minus CRN difference was related to arousal but not valence ratings in multiple regression analyses. Affect-related differences were not shown for the Pe. Findings provide a context to understand how dimensional aspects of emotional valence and arousal influence performance-monitoring processes and suggest a need for further research on the functional role of the CRN and its relation to affective valence. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. High Valence, Normal Valence and Unknown Valence

    DEFF Research Database (Denmark)

    Morsing, Thorbjørn Juul

    characterised by EPR and the powder spectra successfully simulated using two generic multiplet Hamiltonians, one for S = 2 and one for S = 3. The exchange coupling in chromium diols are investigated with a Broken Symmetry DFT model, which is able to accurately predict the exchange coupling constant J from...... weakly to strongly coupled systems. This represents a quantitative improvement over the established GHP model based on AOM arguments, and the qualitative interpretation of said model is corroborated by in silica magnetostructural correlation studies. Chapter 2 details a single crystal EPR study...... on dinuclear chromium(III) compounds. (Ph4P)4[(SCN)4Cr(OH)2Cr(NCS)4] 2 NCCH3 is investigated again as a ’proof of concept’ that it is possible to accurately simulate the single crystal spectra of a low-symmetry system (monoclinic) where two orientations of the molecules are present in the unit cell...

  18. Electron polarization function and plasmons in metallic armchair graphene nanoribbons

    DEFF Research Database (Denmark)

    Shylau, A. A.; Badalyan, S. M.; Peeters, F. M.

    2015-01-01

    to the phase space redistribution among inter-band and intra-band electronic transitions in the conduction and valence bands, the full polarization function becomes independent of temperature and position of the chemical potential. It is shown that for a given width of nanoribbon there exists a single plasmon...

  19. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  20. Concentration risk

    Directory of Open Access Journals (Sweden)

    Matić Vesna

    2016-01-01

    Full Text Available Concentration risk has been gaining a special dimension in the contemporary financial and economic environment. Financial institutions are exposed to this risk mainly in the field of lending, mostly through their credit activities and concentration of credit portfolios. This refers to the concentration of different exposures within a single risk category (credit risk, market risk, operational risk, liquidity risk.

  1. Analysis of EEG variables to measure the affective dimensions of arousal and valence related to the vision of emotional pictures.

    Science.gov (United States)

    Gaeta, G; Susac, A; Supek, S; Babiloni, F; Vecchiato, G

    2015-01-01

    The present work aims to investigate the electroencephalographic (EEG) activity elicited by the observation of emotional pictures selected from the International Affective Picture System (IAPS) database. We analyzed the evoked activity within time intervals of increasing duration taking into account the related ratings of Valence and Arousal. The scalp statistical maps of Power Spectral Density (PSD), related to pictures with high valence, revealed an enhanced activity across frontal areas in the theta band and the involvement of fronto-parietal circuits in the alpha band. Difference in the processing of low and high arousing pictures, however, seems to be highly dependent on the valence dimension: for low valenced pictures, the difference in arousal was processed immediately after the observation of the picture, while for the high-valenced ones the processing took part in the second part of the observation. These results appear to be congruent with the literature, while the novelty of the current study is represented by the comparison of the activity elicited in different time windows by both the Arousal and Valence dimensions. It is possible, in this way, to observe how the processing of one variable influences the other, creating a dynamic description of the Valence-Arousal space.

  2. Electronic Structure of Lanthanide Scandates

    OpenAIRE

    Mizzi, Christopher A.; Koirala, Pratik; Marks, Laurence D.

    2017-01-01

    X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and density functional theory were used to study the electronic structure of three lanthanide scandates: GdScO3, TbScO3, and DyScO3. X-ray photoelectron spectra simulated from first principles calculations using a combination of on-site hybrid and GGA+U methods were found to be in good agreement with experimental x-ray photoelectron spectra. From these results, the lanthanide scandate valence bands were determined to be...

  3. Analysis of valence XPS and AES of (PP, P4VP, PVME, PPS, PTFE) polymers by DFT calculations using the model molecules

    Science.gov (United States)

    Endo, Kazunaka; Shimada, Shingo; Kato, Nobuhiko; Ida, Tomonori

    2016-10-01

    We simulated valence X-ray photoelectron spectra (VXPS) of five [(CH2CH(CH3))n {poly(propyrene) PP}, ((CH2CH(C5NH4))n {poly(4-vinyl-pyridine) P4VP}, (CH2CHO(CH3))n {poly(vinyl methyl ether) PVME}, (C6H4S)n {poly(phenylene) sulphide PPS}, (CF2CF2)n {poly(tetrafluoroethylene) PTFE}] polymers by density-functional theory (DFT) calculations using the model oligomers. The spectra reflect the differences in the chemical structures between each polymer, since the peak intensities of valence band spectra are seen to be due to photo-ionization cross-section of (C, N, O, S, F) atoms by considering the orbital energies and cross-section values of the polymer models, individually. In the Auger electron spectra (AES) simulations, theoretical kinetic energies of the AES are obtained with our modified calculation method. The modified kinetic energies correspond to two final-state holes at the ground state and at the transition-state in DFT calculations, respectively. Experimental peaks of (C, N, O)- KVV, and S L2,3VV AES for each polymer are discussed in detail by our modified calculation method.

  4. Orbital ordering and valence states in ( La1+x Ca1-x ) CoRu O6 double perovskites

    Science.gov (United States)

    Bos, Jan-Willem G.; Attfield, J. Paul; Chan, Ting-Shan; Liu, Ru-Shi; Jang, Ling-Yun

    2005-07-01

    (La1+xCa1-x)CoRuO6 double perovskites have been studied by neutron diffraction and x-ray absorption spectroscopy. The thermal evolution of the (LaCa)CoRuO6 structure has been investigated between 4 and 1073K using neutron powder diffraction. The cell b axis shows a crossover from negative to positive thermal expansion at T≈425K , which is accompanied by a discontinuity in the c axis. This is shown to result from a partial orbital ordering of the Co2+ t2g holes. Ru valence states of doped (La1+xCa1-x)CoRuO6 (-0.25⩽x⩽0.25) materials have been investigated using XANES spectroscopy. Electron-doping (x>0) leads to reduction of Ru5+→Ru4+ while hole-doped x⩽0 compositions have a constant Ru5+ state. These observations support a proposed asymmetric doping model.

  5. Quantifying van der Waals Interactions in Layered Transition Metal Dichalcogenides from Pressure-Enhanced Valence Band Splitting.

    Science.gov (United States)

    Ci, Penghong; Chen, Yabin; Kang, Jun; Suzuki, Ryuji; Choe, Hwan Sung; Suh, Joonki; Ko, Changhyun; Park, Taegyun; Shen, Ke; Iwasa, Yoshihiro; Tongay, Sefaattin; Ager, Joel W; Wang, Lin-Wang; Wu, Junqiao

    2017-08-09

    van der Waals (vdW) forces, despite being relatively weak, hold the layers together in transition metal dichalcogenides (TMDs) and play a key role in their band structure evolution, hence profoundly affecting their physical properties. In this work, we experimentally probe the vdW interactions in MoS 2 and other TMDs by measuring the valence band maximum (VBM) splitting (Δ) at K point as a function of pressure in a diamond anvil cell. As high pressure increases interlayer wave function coupling, the VBM splitting is enhanced in 2H-stacked MoS 2 multilayers but, due to its specific geometry, not in 3R-stacked multilayers, hence allowing the interlayer contribution to be separated out of the total VBM splitting, as well as predicting a negative pressure (2.4 GPa) where the interlayer contribution vanishes. This negative pressure represents the threshold vdW interaction beyond which neighboring layers are electronically decoupled. This approach is compared to first-principles calculations and found to be widely applicable to other group-VI TMDs.

  6. The Impacts of Graphene Nanosheets and Manganese Valency on Lithium Storage Characteristics in Graphene/Manganese Oxide Hybrid Anode

    Directory of Open Access Journals (Sweden)

    S. L. Cheekati

    2012-01-01

    Full Text Available Graphene nanosheets (GNS with attached MnOx nanoparticles are studied in regard to their structure and morphology. The relationship between the lithium storage performances and GNS contents as well as manganese valency was investigated. Experimental results showed that the specimen with 44 wt% GNS and high content of MnO delivered high reversible capacity (over twice of that in graphitic carbon anode, good cycling stability (0.8% fading per cycle, and high rate capability (67% at the 800 mA/g, which are dramatically better than pure Mn3O4. The improvement is attributed to the presence of GNS which provides continuous networks for fast electronic conduction and mechanical flexibility for accommodating the large volume change. The MnOx/GNS hybrid material has the added advantages over pure GNS, benefiting from its lithium storage potential of around 0.5 V which not only ensures high rate capability but also reduces the risk of metallic lithium formation with its safety hazard.

  7. Positively-valenced stimuli facilitate creative novel metaphoric processes by enhancing medial prefrontal cortical (mPFC activation

    Directory of Open Access Journals (Sweden)

    Karuna eSubramaniam

    2013-04-01

    Full Text Available A metaphor is a figure of speech in which a subject is symbolic of another unrelated object. In the present study, we examined neural patterns associated with both novel unfamiliar and conventional familiar metaphoric processing, and how these patterns are modulated by affective valence. Prior to fMRI scanning, participants received a list of word pairs (novel unfamiliar metaphors as well as conventional familiar metaphors and were asked to denote the valence (positive, negative, or neutral of each word pair. During scanning, participants had to decide whether the word pairs formed meaningful or meaningless expressions. Results indicate that participants were faster and more accurate at deciding that positively-valenced metaphors were meaningful compared to neutral metaphors. These behavioral findings were accompanied by increased activation in the medial prefrontal cortex (mPFC, posterior cingulate cortex (PCC, and the right inferior parietal lobe (IPL. Specifically, positively-valenced novel unfamiliar metaphors elicited activation in these brain regions in addition to the left superior temporal gyrus when compared to neutral novel metaphors. We also found that the mPFC and PCC mediated the processing of positively-valenced metaphors when compared to negatively-valenced metaphors. Positively-valenced conventional metaphors, however, elicited different neural signatures when contrasted with either neutral or negatively-valenced conventional metaphors. Together, our results indicate that positively-valenced stimuli facilitate creative metaphoric processes (specifically novel metaphoric processes by mediating attention and cognitive control processes required for the access, integration and selection of semantic associations via modulation of the mPFC. The present study is important for the development of neural accounts of emotion-cognition interactions required for creativity, language and successful social functioning in general.

  8. Concentrator Photovoltaics

    CERN Document Server

    Luque, Antonio L

    2007-01-01

    Photovoltaic solar-energy conversion is one of the most promising technologies for generating renewable energy, and conversion of concentrated sunlight can lead to reduced cost for solar electricity. In fact, photovoltaic conversion of concentrated sunlight insures an efficient and cost-effective sustainable power resource. This book gives an overview of all components, e.g. cells, concentrators, modules and systems, for systems of concentrator photovoltaics. The authors report on significant results related to design, technology, and applications, and also cover the fundamental physics and market considerations. Specific contributions include: theory and practice of sunlight concentrators; an overview of concentrator PV activities; a description of concentrator solar cells; design and technology of modules and systems; manufacturing aspects; and a market study.

  9. Identification of chemical warfare agents from vapor samples using a field-portable capillary gas chromatography/membrane-interfaced electron ionization quadrupole mass spectrometry instrument with Tri-Bed concentrator.

    Science.gov (United States)

    Nagashima, Hisayuki; Kondo, Tomohide; Nagoya, Tomoki; Ikeda, Toru; Kurimata, Naoko; Unoke, Shohei; Seto, Yasuo

    2015-08-07

    A field-portable gas chromatograph-mass spectrometer (Hapsite ER system) was evaluated for the detection of chemical warfare agents (CWAs) in the vapor phase. The system consisted of Tri-Bed concentrator gas sampler (trapping time: 3s(-1)min), a nonpolar low thermal-mass capillary gas chromatography column capable of raising temperatures up to 200°C, a hydrophobic membrane-interfaced electron ionization quadrupole mass spectrometer evacuated by a non-evaporative getter pump for data acquisition, and a personal computer for data analysis. Sample vapors containing as little as 22μg sarin (GB), 100μg soman (GD), 210μg tabun (GA), 55μg cyclohexylsarin (GF), 4.8μg sulfur mustard, 390μg nitrogen mustard 1, 140μg of nitrogen mustard 2, 130μg nitrogen mustard 3, 120μg of 2-chloroacetophenone and 990μg of chloropicrin per cubic meter could be confirmed after Tri-Bed micro-concentration (for 1min) and automated AMDIS search within 12min. Using manual deconvolution by background subtraction of neighboring regions on the extracted ion chromatograms, the above-mentioned CWAs could be confirmed at lower concentration levels. The memory effects were also examined and we found that blister agents showed significantly more carry-over than nerve agents. Gasoline vapor was found to interfere with the detection of GB and GD, raising the concentration limits for confirmation in the presence of gasoline by both AMDIS search and manual deconvolution; however, GA and GF were not subject to interference by gasoline. Lewisite 1, and o-chlorobenzylidene malononitrile could also be confirmed by gas chromatography, but it was hard to quantify them. Vapors of phosgene, chlorine, and cyanogen chloride could be confirmed by direct mass spectrometric detection at concentration levels higher than 2, 140, and 10mg/m(3) respectively, by bypassing the micro-concentration trap and gas chromatographic separation. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Evaluation of the effect of valence state on cerium oxide nanoparticle toxicity following intratracheal instillation in rats

    OpenAIRE

    Dunnick, Katherine M.; Morris, Anna M.; Badding, Melissa A.; Barger, Mark; Stefaniak, Aleksandr B.; Sabolsky, Edward M.; Leonard, Stephen S.

    2016-01-01

    Cerium (Ce) is becoming a popular metal for use in electrochemical applications. When in the form of cerium oxide (CeO2), Ce can exist in both 3 + and 4 + valence states, acting as an ideal catalyst. Previous in vitro and in vivo evidence have demonstrated that CeO2 has either anti- or pro-oxidant properties, possibly due to the ability of the nanoparticles to transition between valence states. Therefore, we chose to chemically modify the nanoparticles to shift the valence state toward 3+. Du...

  11. Ab initio effective core potentials including relativistic effects and their application to the electronic structure calculations of heavy atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.S.

    1977-11-01

    The effects of the 4f shell of electrons and the relativity of valence electrons are compared. The effect of 4f shell (lanthanide contraction) is estimated from the numerical Hartree-Fock (HF) calculations of pseudo-atoms corresponding to Hf, Re, Au, Hg, Tl, Pb and Bi without 4f electrons and with atomic numbers reduced by 14. The relativistic effect estimated from the numerical Dirac-Hartree-Fock (DHF) calculations of those atoms is comparable in the magnitude with that of the 4f shell of electrons. Both are larger for 6s than for 5d or 6p electrons. The various relativistic effects on valence electrons are discussed in detail to determine the proper level of the approximation for the valence electron calculations of systems with heavy elements. An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials.

  12. Electron momentum density and the momentum density of positron annihilation pairs in alkali metals: high-momentum components

    Energy Technology Data Exchange (ETDEWEB)

    Sob, M.

    1985-08-01

    The valence electron momentum density (EMD) and the momentum density of positron annihilation pairs (MDAP) are calculated ab initio for alkali metals from Li to Cs. It is shown that the proportion of valence electrons having their momenta within the central Fermi surface ranges from 75% (Cs) to 93% (Na); the momenta of the remaining valence electrons lie in the Umklapp Fermi surfaces centred at the surrounding reciprocal lattice points. In the calculation of the MDAP, various enhancement factors describing the effect of the many-body electron-positron interaction are examined; it seems that the recent model of enhancement of Umklapp terms presented by Sormann et al is not fully adequate. A relation between the EMD and MDAP is briefly discussed and the connection between the occupation of the central Fermi surface and other parameters of the electronic structure is pointed out.

  13. Valence band energy spectrum of HgTe quantum wells with an inverted band structure

    Science.gov (United States)

    Minkov, G. M.; Aleshkin, V. Ya.; Rut, O. E.; Sherstobitov, A. A.; Germanenko, A. V.; Dvoretski, S. A.; Mikhailov, N. N.

    2017-07-01

    The energy spectrum of the valence band in HgTe /CdxHg1 -xTe quantum wells of a width (8 -20 ) nm has been studied experimentally by magnetotransport effects and theoretically in the framework of a four-band k P method. Comparison of the Hall density with the density found from a period of the Shubnikov-de Haas (SdH) oscillations clearly shows that the degeneracy of states of the top of the valence band is equal to 2 at the hole density p SdH oscillations shows that mh is equal to (0.25 ±0.02 ) m0 and weakly increases with the hole density. Such a value of mh and its dependence on the hole density are in a good agreement with the calculated effective mass.

  14. Continuum limit of overlap valence quarks on a twisted mass sea

    Energy Technology Data Exchange (ETDEWEB)

    Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; Jansen, Karl [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC

    2010-12-15

    We study a lattice QCD mixed action with overlap valence quarks on two flavours of Wilson maximally twisted mass sea quarks. Employing three different matching conditions to relate both actions to each other, we investigate the continuum limit by using three values of the lattice spacing ranging from a{approx}0.05 fm to 0.08 fm. A particular emphasis is put on the effect on physical observables of the topological zero modes appearing in the valence overlap operator. We estimate the region of parameter space where the contribution from these zero modes is sufficiently small such that their effects can be safely controlled and a restoration of unitarity of the mixed action in the continuum limit is reached. (orig.)

  15. Mushroom body output neurons encode valence and guide memory-based action selection in Drosophila.

    Science.gov (United States)

    Aso, Yoshinori; Sitaraman, Divya; Ichinose, Toshiharu; Kaun, Karla R; Vogt, Katrin; Belliart-Guérin, Ghislain; Plaçais, Pierre-Yves; Robie, Alice A; Yamagata, Nobuhiro; Schnaitmann, Christopher; Rowell, William J; Johnston, Rebecca M; Ngo, Teri-T B; Chen, Nan; Korff, Wyatt; Nitabach, Michael N; Heberlein, Ulrike; Preat, Thomas; Branson, Kristin M; Tanimoto, Hiromu; Rubin, Gerald M

    2014-12-23

    Animals discriminate stimuli, learn their predictive value and use this knowledge to modify their behavior. In Drosophila, the mushroom body (MB) plays a key role in these processes. Sensory stimuli are sparsely represented by ∼2000 Kenyon cells, which converge onto 34 output neurons (MBONs) of 21 types. We studied the role of MBONs in several associative learning tasks and in sleep regulation, revealing the extent to which information flow is segregated into distinct channels and suggesting possible roles for the multi-layered MBON network. We also show that optogenetic activation of MBONs can, depending on cell type, induce repulsion or attraction in flies. The behavioral effects of MBON perturbation are combinatorial, suggesting that the MBON ensemble collectively represents valence. We propose that local, stimulus-specific dopaminergic modulation selectively alters the balance within the MBON network for those stimuli. Our results suggest that valence encoded by the MBON ensemble biases memory-based action selection.

  16. Memory transfer for emotionally valenced words between identities in dissociative identity disorder.

    Science.gov (United States)

    Huntjens, Rafaële J C; Peters, Madelon L; Woertman, Liesbeth; van der Hart, Onno; Postma, Albert

    2007-04-01

    The present study aimed to determine interidentity retrieval of emotionally valenced words in dissociative identity disorder (DID). Twenty-two DID patients participated together with 25 normal controls and 25 controls instructed to simulate DID. Two wordlists A and B were constructed including neutral, positive and negative material. List A was shown to one identity, while list B was shown to another identity claiming total amnesia for the words learned by the first identity. The identity claiming amnesia was tested for intrusions from list A words into the recall of words from list B and recognition of the words learned by both identities. Test results indicated no evidence of total interidentity amnesia for emotionally valenced material in DID. It is argued that dissociative amnesia in DID may more adequately be described as a disturbance in meta-memory functioning instead of an actual retrieval inability.

  17. Are valence and social avoidance associated with the memory conformity effect?

    Science.gov (United States)

    Wright, D B; Busnello, R H D; Buratto, L G; Stein, L M

    2012-09-01

    Pairs of participants were shown photographs which varied in terms of valence from negative to positive, and two days later, together, they were given a memory recognition test. When the first person responded the second person saw the response. This affected how the second person responded, what is called memory conformity. The memory conformity effect was larger for previously unseen stimuli (fillers) than for previously seen stimuli (targets), and was greatest for those with low scores on a social avoidance measure. While memory for negative (and most arousing) stimuli was most accurate, the memory conformity effect did not differ significantly by the stimulus valence. Implications for theories of memory malleability and for assessing the reliability of memories in a forensic context are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Stabilization of Th 3+ ions into mixed-valence thorium fluoride

    Science.gov (United States)

    Dubois, Marc; Dieudonné, Belto; Mesbah, Adel; Bonnet, Pierre; El-Ghozzi, Malika; Renaudin, Guillaume; Avignant, Daniel

    2011-01-01

    The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li 2+ xTh 12F 50 (0afore mentioned single phase may be considered as an insertion compound. The Li + insertion is accompanied by the simultaneous reduction of a part of the Th 4+ ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li + ions into the open channels of the host matrix has been carried out at 60 °C, using an alkylcarbonate PC-LiClO 4 1 M electrolyte. The Li + and Th 3+ contents, both in the starting composition and the Li + inserted ones, were investigated by high resolution solid state 7Li NMR and EPR, respectively.

  19. Organization of Valence-Encoding and Projection-Defined Neurons in the Basolateral Amygdala

    Directory of Open Access Journals (Sweden)

    Anna Beyeler

    2018-01-01

    Full Text Available The basolateral amygdala (BLA mediates associative learning for both fear and reward. Accumulating evidence supports the notion that different BLA projections distinctly alter motivated behavior, including projections to the nucleus accumbens (NAc, medial aspect of the central amygdala (CeM, and ventral hippocampus (vHPC. Although there is consensus regarding the existence of distinct subsets of BLA neurons encoding positive or negative valence, controversy remains regarding the anatomical arrangement of these populations. First, we map the location of more than 1,000 neurons distributed across the BLA and recorded during a Pavlovian discrimination task. Next, we determine the location of projection-defined neurons labeled with retrograde tracers and use CLARITY to reveal the axonal path in 3-dimensional space. Finally, we examine the local influence of each projection-defined populations within the BLA. Understanding the functional and topographical organization of circuits underlying valence assignment could reveal fundamental principles about emotional processing.

  20. Embedding values: how science and society jointly valence a concept-the case of ADHD.

    Science.gov (United States)

    Hawthorne, Susan

    2010-03-01

    Many successful sciences both serve and shape human ends. Conversely, the societies in which these sciences are practiced support the research and provide interpretive context. These mutual influences may result in a positive feedback loop that reinforces constitutive and contextual values, embedding them in scientific concepts: the ADHD concept is a case in point. In an ongoing process, social considerations fuel investigational choices and contexts for evaluating data. Scientific study forwards the feedback loop through the influence of investigative trends, by directly and indirectly embedding values in data interpretation, and by core methodologies that heighten the contrast between 'ADHD' and 'normal'. The resulting scientific conclusions embed value valences in the ADHD concept; social uptake of that valenced concept begins another round of interest in its implications and support of the science. The processes at work in the ADHD case are very general, so we should expect to see similar processes and results in other fields. Copyright 2009 Elsevier Ltd. All rights reserved.