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Sample records for energy of dissociation

  1. Dissociation Energies of Diatomic Molecules

    International Nuclear Information System (INIS)

    Qun-Chao, Fan; Wei-Guo, Sun

    2008-01-01

    Molecular dissociation energies of 10 electronic states of alkali molecules of KH, 7 LiD, 7 LiH, 6 LiH, NaK, NaLi and NaRb are studied using the highest three accurate vibrational energies of each electronic state, and an improved parameter-free analytical formula which is obtained starting from the LeRoy–Bernstein vibrational energy expression near the dissociation limit. The results show that as long as the highest three vibrational energies are accurate, the current analytical formula will give accurate theoretical dissociation energies D e theory , which are in excellent agreement with the experimental dissociation energies D e expt . (atomic and molecular physics)

  2. Energy distribution in dissociations of polyatomic molecules

    International Nuclear Information System (INIS)

    Koernig, S.A.

    1989-01-01

    In this thesis studies are reported of fragmentation processes in polyatomic molecules. In order to find out which dessocaciation reactions take place, how they are brought about by the internal energy of the reactant, and to investigate the structure of the dissociating 'transition state', the fragment mass and the corresponding kinetic energy release (KER) are determined by differential translational spectroscopy using a position and time sensitive two-particle coincidence detector. The results are interpreted using the statistical theory of unimolecular dissociation. It turns out that the standard assumptions of the theory, especially in calculating KER-distributions, are not realistic in all molecules considered. Dissociation is induced by the neutralization with alkali metal vapour. In ch. 2 the experimental method and the analysis of the data (dissociation pathways, branching ratios and ε-d-distributions) are introduced and exemplified by measurements of cyclohexane, which represents the upper limit in precursor and fragment mass accessible in the apparatus. In ch. 3 a study is reported of the molecules methylchloride (CH 3 Cl) and the acetylradical (CH 3 CO). In spite of their similar geometric structures, completely different dissociation mechanisms have been found. Methylchloride dissociates via a repulsive state; acetyl radicals show energy scrambling. The energy distribution from dissociating acetyl exemplifies dynamical effects in the dissociation. In ch. 4 an investigation of a number of prototype hydrocarbons is presented. The dissociation pathways of several small linear alkanes indicate that neutralization takes place to unknown repulsive potentials, of which the position and steepness are determined from the kinetic energy release. (author). 118 refs.; 40 figs.; 5 tabs

  3. Dissociation energy of the ground state of NaH

    International Nuclear Information System (INIS)

    Huang, Hsien-Yu; Lu, Tsai-Lien; Whang, Thou-Jen; Chang, Yung-Yung; Tsai, Chin-Chun

    2010-01-01

    The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9≤v '' ≤21 and 1≤J '' ≤14 were assigned to the X 1 Σ + state of NaH. The highest vibrational level observed was only about 40 cm -1 from the dissociation limit in the ground state. One quasibound state, above the dissociation limit and confined by the centrifugal barrier, was observed. Determining the vibrational quantum number at dissociation v D from the highest four vibrational levels yielded the dissociation energy D e =15 815±5 cm -1 . Based on new observations and available data, a set of Dunham coefficients and the rotationless Rydberg-Klein-Rees curve were constructed. The effective potential curve and the quasibound states were discussed.

  4. Studies of neutron dissociation at Fermilab energies

    International Nuclear Information System (INIS)

    Ferbel, T.

    1975-01-01

    The latest results obtained in a continuing investigation of neutron dissociation in (pπ - ) systems in neutron--nucleus collisions between 50 and 300 GeV/c are summarized. The nuclear coherent dissociation data are discussed first; then new measurements of total cross sections of neutrons on nuclei in the Fermilab momentum range are presented; finally, neutron dissociation using a hydrogen target is considered, and the hydrogen data are compared with expectations from simple Deck models. A substantial correlation was observed between the mass and the t of the system produced. The spin structure of the pπ - amplitudes at low mass was described surprisingly well by the simple Deck mechanism. The t-channel helicity amplitudes contained comparable contributions from flip and nonflip terms, and the states produced were not restricted to those expected on the basis of the Morrison rule. (19 figures, 2 tables) (U.S.)

  5. Model-independent determination of dissociation energies: method and applications

    International Nuclear Information System (INIS)

    Vogel, Manuel; Hansen, Klavs; Herlert, Alexander; Schweikhard, Lutz

    2003-01-01

    A number of methods are available for the purpose of extracting dissociation energies of polyatomic particles. Many of these techniques relate the rate of disintegration at a known excitation energy to the value of the dissociation energy. However, such a determination is susceptible to systematic uncertainties, mainly due to the unknown thermal properties of the particles and the potential existence of 'dark' channels, such as radiative cooling. These problems can be avoided with a recently developed procedure, which applies energy-dependent reactions of the decay products as an uncalibrated thermometer. Thus, it allows a direct measurement of dissociation energies, without any assumption on properties of the system or on details of the disintegration process. The experiments have been performed in a Penning trap, where both rate constants and branching ratios have been measured. The dissociation energies determined with different versions of the method yield identical values, within a small uncertainty

  6. Models for calculation of dissociation energies of homonuclear diatomic molecules

    International Nuclear Information System (INIS)

    Brewer, L.; Winn, J.S.

    1979-08-01

    The variation of known dissociation energies of the transition metal diatomics across the Periodic Table is rather irregular like the bulk sublimation enthalpy, suggesting that the valence-bond model for bulk metallic systems might be applicable to the gaseous diatomic molecules and the various intermediate clusters. Available dissociation energies were converted to valence-state bonding energies considering various degrees of promotion to optimize the bonding. The degree of promotion of electrons to increase the number of bonding electrons is smaller than for the bulk, but the trends in bonding energy parallel the behavior found for the bulk metals. Thus using the established trends in bonding energies for the bulk elements, it was possible to calculate all unknown dissociation energies to provide a complete table of dissociation energies for all M 2 molecules from H 2 to Lr 2 . For solids such as Mg, Al, Si and most of the transition metals, large promotion energies are offset by strong bonding between the valence state atoms. The main question is whether bonding in the diatomics is adequate to sustain extensive promotion. The most extreme example for which a considerable difference would be expected between the bulk and the diatomics would be that of the Group IIA and IIB metals. The first section of this paper which deals with the alkaline earths Mg and Ca demonstrates a significant influence of the excited valence state even for these elements. The next section then expands the treatment to transition metals

  7. Lifetime and kinetic energy release of metastable dications dissociation

    International Nuclear Information System (INIS)

    Alagia, M.; Candori, P.; Falcinelli, S.; Mundim, K.C.; Mundim, M.S.P.; Pirani, F.; Richter, R.; Stranges, S.; Vecchiocattivi, F.

    2012-01-01

    Graphical abstract: A statistical method is proposed for extracting dynamics information from coincidence data in double photoionization of molecules. Highlights: ► When a photon, with sufficient energy, hits a molecule, a doubly charged ion can be formed. This dication has often a large probability of dissociate in two positive singly charged ions. ► Experiments of photoelectron–photoion–photoion coincidence can provide valuable information about the dynamics of such dissociation processes. ► A statistical method is proposed for extracting such information from the coincidence data. - Abstract: A new method for the determination of dynamical features of the molecular dication dissociation processes, following the single photon double ionization, investigated by time-of-flight mass spectrometry technique has been developed. The method is based on an extension of the generalized simulated annealing statistical methodology, previously applied in other fields. Here it is described and applied, as an example, to the case of the dissociation of the CO 2 2+ dication giving CO + + O + ion fragments. The results are consistent with previous determination of the metastable lifetime of the dication, but the analysis also provides additional information about the dynamics of the reaction.

  8. Predissociation measurements of bond dissociation energies: VC, VN, and VS

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Eric L.; Davis, Quincy C.; Morse, Michael D. [Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States)

    2016-06-21

    The abrupt onset of predissociation in the congested electronic spectra of jet-cooled VC, VN, and VS has been observed using resonant two-photon ionization spectroscopy. It is argued that because of the high density of electronic states in these molecules, the predissociation threshold occurs at the thermochemical threshold for the production of separated atoms in their ground electronic states. As a result, the measured threshold represents the bond dissociation energy. Using this method, bond dissociation energies of D{sub 0}(V C) = 4.1086(25) eV, D{sub 0}(V N) = 4.9968(20) eV, and D{sub 0}(V S) = 4.5353(25) eV are obtained. From these values, enthalpies of formation are derived as Δ{sub f,0K}H°(V C(g)) = 827.0 ± 8 kJ mol{sup −1}, Δ{sub f,0K}H°(V N(g)) = 500.9 ± 8 kJ mol{sup −1}, and Δ{sub f,0K}H°(V S(g)) = 349.3 ± 8 kJ mol{sup −1}. Using a thermochemical cycle and the well-known ionization energies of V, VC, and VN, our results also provide D{sub 0}(V{sup +}–C) = 3.7242(25) eV and D{sub 0}(V{sup +}–N) = 4.6871(20) eV. These values are compared to previous measurements and to computational results. The precision of these bond dissociation energies makes them good candidates for testing computational chemistry methods, particularly those that employ density functional theory.

  9. Studies of neutron dissociation at FermiLab energies

    International Nuclear Information System (INIS)

    Ferbel, T.

    1975-01-01

    The characteristics of diffraction dissociation of neutrons into pπ - systems at high energies were examined. A substantial correlation is observed between the mass and the t of the produced system. The spin structure of the pπ - amplitudes at low mass is very complex, but is described surprisingly well by the simple Deck Mechanism. Both π-exchange and proton-exchange contributions are evident in diffractive production. The t-channel and s-channel helicity amplitudes contain comparable contributions from flip and nonflip terms and the produced states are not restricted to those expected on the basis of the Morrison rule

  10. Direct measurement of exciton dissociation energy in polymers

    Czech Academy of Sciences Publication Activity Database

    Toušek, J.; Toušková, J.; Chomutová, R.; Paruzel, Bartosz; Pfleger, Jiří

    2017-01-01

    Roč. 7, č. 1 (2017), s. 1-6, č. článku 015113. ISSN 2158-3226 Institutional support: RVO:61389013 Keywords : exciton dissociation energy * polymers * SCR Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 1.568, year: 2016

  11. Study of dissociative collisions of hydrogen-line ions by mean of angular and energy distributions

    International Nuclear Information System (INIS)

    Martinez, H.; Urquijo, J. de; Cisneros, C.; Alvarez, J.

    1988-01-01

    Angular and energy distribution of fragments produced in a collision, employed in conjunction with the 'step-model' that means excitation and binary dissociation, are used to determine the binding energy of H 3 (D 3 ) and HD + 2 and also to identify the principal channels in the dissociation processes. (A.C.A.S.) [pt

  12. Energy localization and molecular dissociation

    International Nuclear Information System (INIS)

    Takeno, S.; Tsironis, G.P.

    2005-01-01

    We study analytically as well as numerically the role that large-amplitude vibrations play during the process of molecular dissociation. Our model consists of a linear three-atom molecule composed of identical atoms interacting with their nearest neighbors by Morse potentials. We find a close relation between energy localization and bond breaking and evaluate numerically the corresponding reaction paths

  13. Dissociative recombination of the CH+ molecular ion at low energy

    Science.gov (United States)

    Chakrabarti, K.; Mezei, J. Zs; Motapon, O.; Faure, A.; Dulieu, O.; Hassouni, K.; Schneider, I. F.

    2018-05-01

    The reactive collision of the CH+ molecular ion with an electron is studied in the framework of the multichannel quantum defect theory, taking into account the contribution of the core-excited Rydberg states. In addition to the X 1Σ+ ground state of the ion, we also consider the contribution to the dynamics of the a 3Π and A 1Π excited states of CH+. Our results—in the case of the dissociative recombination in good agreement with the storage ring measurements—rely on decisive improvements—complete account of the ionisation channels and accurate evaluation of the reaction matrix—of a previously used model.

  14. Electron-Nuclear Energy Sharing in Above-Threshold Multiphoton Dissociative Ionization of H2

    DEFF Research Database (Denmark)

    Wu, J.; Kunitski, M.; Pitzer, M.

    2013-01-01

    We report experimental observation of the energy sharing between electron and nuclei in above-threshold multiphoton dissociative ionization of H2 by strong laser fields. The absorbed photon energy is shared between the ejected electron and nuclei in a correlated fashion, resulting in multiple...... diagonal lines in their joint energy spectrum governed by the energy conservation of all fragment particles....

  15. Ab initio study of dissociative attachment of low-energy electrons to F2

    International Nuclear Information System (INIS)

    Hazi, A.U.; Orel, A.E.; Rescigno, T.N.

    1981-01-01

    Adiabatic-nuclei resonance theory has been applied to the study of dissociative attachment of low-energy electrons to F 2 . Stieltjes moment theory was used to derive fixed-nuclei electronic resonance parameters from large scale configuration-interaction calculations on F 2 and F 2 - . Dissociative attachment cross sections are reported for the four lowest vibrational levels of F 2 and compared to available experimental data

  16. Dissociative chemisorption of N2 on Rhenium: Dynamics at high impact energies

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Billing, Gert D.; Hansen, Flemming Yssing

    1990-01-01

    forcing model. It is found that the energy transfer from the molecule to the phonons of the crystal is very significant. The smaller than unity dissociative sticking probability found experimentally even at the highest impact energies well above the barrier energy can be accounted for by the Landau...

  17. Excitation and dissociation of molecules by low-energy (0-15 eV) electrons

    International Nuclear Information System (INIS)

    Verhaart, G.J.

    1980-01-01

    The author deals with excitation and dissociation processes which result from the interaction between low-energy (0.15 eV) electrons and molecules. Low-energy electron-impact spectroscopy is used to gain a better knowledge of the electronic structure of halomethanes, ethylene and some of its halogen substituted derivatives, and some more complex organic molecules. (Auth.)

  18. Multiphoton dissociation of polyatomic molecules

    International Nuclear Information System (INIS)

    Schulz, P.A.

    1979-10-01

    The dynamics of infrared multiphoton excitation and dissociation of SF 6 was investigated under collision free conditions by a crossed laser-molecular beam method. In order to understand the excitation mechanism and to elucidate the requirements of laser intensity and energy fluence, a series of experiments were carried out to measure the dissociation yield dependences on energy fluence, vibrational temperature of SF 6 , the pulse duration of the CO 2 laser and the frequency in both one and two laser experiments. Translational energy distributions of the SF 5 dissociation product measured by time of flight and angular distributions and the dissociation lifetime of excited SF 6 as inferred from the observation of secondary dissociation of SF 5 into SF 4 and F during the laser pulse suggest that the dynamics of dissociation of excited molecules is dominated by complete energy randomization and rapid intramolecular energy transfer on a nanosecond timescale, and can be adequately described by RRKM theory. An improved phenomenological model including the initial intensity dependent excitation, a rate equation describing the absorption and stimulated emission of single photons, and the unimolecular dissociation of excited molecules is constructed based on available experimental results. The model shows that the energy fluence of the laser determines the excitation of molecules in the quasi-continuum and the excess energy with which molecules dissociate after the laser pulse. The role played by the laser intensity in multiphoton dissociation is more significant than just that of overcoming the intensity dependent absorption in the lowest levels. 63 references

  19. Dissociation energies of six NO2 isotopologues by laser induced fluorescence spectroscopy and zero point energy of some triatomic molecules.

    Science.gov (United States)

    Michalski, G; Jost, R; Sugny, D; Joyeux, M; Thiemens, M

    2004-10-15

    We have measured the rotationless photodissociation threshold of six isotopologues of NO2 containing 14N, 15N, 16O, and 18O isotopes using laser induced fluorescence detection and jet cooled NO2 (to avoid rotational congestion). For each isotopologue, the spectrum is very dense below the dissociation energy while fluorescence disappears abruptly above it. The six dissociation energies ranged from 25 128.56 cm(-1) for 14N16O2 to 25 171.80 cm(-1) for 15N18O2. The zero point energy for the NO2 isotopologues was determined from experimental vibrational energies, application of the Dunham expansion, and from canonical perturbation theory using several potential energy surfaces. Using the experimentally determined dissociation energies and the calculated zero point energies of the parent NO2 isotopologue and of the NO product(s) we determined that there is a common De = 26 051.17+/-0.70 cm(-1) using the Born-Oppenheimer approximation. The canonical perturbation theory was then used to calculate the zero point energy of all stable isotopologues of SO2, CO2, and O3, which are compared with previous determinations.

  20. Relationship between the Bond dissociation energies and impact sensitivities of some nitro-explosives

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xiao-Shu [School of Physics and Chemistry, Guizhou Normal University, Guiyang (China); Institute of Atomic and Molecular Physics, Sichuan University, Chengdu (China); Cheng, Xin-Lu; Yang, Xiang-Dong [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu (China); He, Bi [Institute of Chemical Materials, CAEP, Mianyang (China)

    2006-08-15

    The bond dissociation energy (BDE) for removal of the NO{sub 2} group for eleven CHNO nitro-containing explosive molecules is studied to find its correlation with impact sensitivity. The BDE for removal of the NO{sub 2} group in nitroaromatic molecules with nitro alkyl, and esters with nitro alkyl, is calculated using the B3LYP method of Density Functional Theory with the 6-31G* basis set. The relationship between the impact sensitivities and the weakest C-NO{sub 2} bond dissociation energy values is examined. The results indicate a nearly linear correlation between the impact sensitivity and the ratio of the BDE value to the total molecular energy. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  1. Time-dependent wave-packet study of the direct low-energy dissociative recombination of HD+

    International Nuclear Information System (INIS)

    Orel, A. E.

    2000-01-01

    Wave-packet methods involving the numerical solution of the time-dependent Schroedinger equation have been used with great success in the calculation of cross sections for dissociative recombination of molecular ions by electron impact in the high energy region where the ''boomerang'' model [L. Dube and A. Herzenberg, Phys. Rev. A 11, 1314 (1975)] is valid. We extend this method to study low-energy dissociative recombination where this approximation is no longer appropriate. We apply the method to the ''direct'' low-energy dissociative recombination of HD + . Our results are in excellent agreement with calculations using the multichannel quantum defect method. (c) 2000 The American Physical Society

  2. A Unified Kinetics and Equilibrium Experiment: Rate Law, Activation Energy, and Equilibrium Constant for the Dissociation of Ferroin

    Science.gov (United States)

    Sattar, Simeen

    2011-01-01

    Tris(1,10-phenanthroline)iron(II) is the basis of a suite of four experiments spanning 5 weeks. Students determine the rate law, activation energy, and equilibrium constant for the dissociation of the complex ion in acid solution and base dissociation constant for phenanthroline. The focus on one chemical system simplifies a daunting set of…

  3. Relationships for the impact sensitivities of energetic C-nitro compounds based on bond dissociation energy.

    Science.gov (United States)

    Li, Jinshan

    2010-02-18

    The ZPE-corrected C-NO(2) bond dissociation energies (BDEs(ZPE)) of a series of model C-nitro compounds and 26 energetic C-nitro compounds have been calculated using density functional theory methods. Computed results show that for C-nitro compounds the UB3LYP calculated BDE(ZPE) is less than the UB3P86 using the 6-31G** basis set, and the UB3P86 BDE(ZPE) changes slightly with the basis set varying from 6-31G** to 6-31++G**. For the series of model C-nitro compounds with different chemical skeletons, it is drawn from NBO analysis that the order of BDE(ZPE) is not only in line with that of the NAO bond order but also with that of the energy gap between C-NO(2) bonding and antibonding orbitals. It is found that for the energetic C-nitro compounds whose drop energies (Es(dr)) are below 24.5 J a good linear correlation exists between E(dr) and BDE(ZPE), implying that these compounds ignite through the C-NO(2) dissociation mechanism. After excluding the so-called trinitrotoluene mechanism compounds, a polynomial correlation of ln(E(dr)) with the BDE(ZPE) calculated at density functional theory levels has been established successfully for the 18 C-NO(2) dissociation energetic C-nitro compounds.

  4. Kinetic-energy distributions of O- produced by dissociative electron attachment to physisorbed O2

    International Nuclear Information System (INIS)

    Huels, M.A.; Parenteau, L.; Michaud, M.; Sanche, L.

    1995-01-01

    We report measurements of the kinetic energy (E k ) distributions of O - produced by low-energy electron impact (5.5--19.5 eV) on disordered multilayers of O 2 physisorbed on a polycrystalline Pt substrate. The results confirm that dissociative electron attachment (DEA) proceeds via the formation of the 2 Π u , 2 Σ g + (I), and 2 Σ x + (II) (x=g and/or u) states of O 2 -* . We also find evidence for an additional resonance, namely the 2 Σ u + (I), positioned at about 10 eV above the neutral ground state in the Franck-Condon region, and dissociating into O - +O( 3 P). The measurements suggest that the autodetachment lifetimes of the 2 Σ u + (I) and 2 Σ g + (II) states may be longer than previously suggested. It is also observed that the effects of electron energy loss (EEL) in the solid prior to DEA, O - scattering in the solid after dissociation, and the charge-induced polarization energy of the solid, broaden the E k distributions, shift them to lower anion energies, and result in additional structure in them. The effects of EEL on the desorption dynamics of O - are estimated from high-resolution electron-energy-loss spectra and excitation functions for losses in the vicinity of the Schumann-Runge continuum of the physisorbed O 2 molecules. We find indications for an enhancement of the optically forbidden X 3 Σ g - →A 3 Σ u + transition, and observe that the gas-phase Rydberg bands, for energy losses above 7 eV, are not distinguishable in the condensed phase

  5. Diffractive dissociation of top hadrons at collider energies

    International Nuclear Information System (INIS)

    Di Bitonto, D.

    1983-01-01

    In an optical model in which heavy-flavour production is described as coherent scattering within the nucleon, the total heavy-flavour cross-section is expected to obey a m q -2 dependence, while the partial differential cross-section dσ/dp T for top hadrons is expected to show a broad plateau above approx. 20 GeV/c in transverse momentum. The expected top hadron signal dσ/dp T is 60 nb for m t = 20 GeV/c 2 appearing in the approx. angular range of expected value of θ 10 deg - 20 deg. (author)

  6. Energy and mass-number dependence of the dissociation temperature in hydrodynamical models

    International Nuclear Information System (INIS)

    Hama, Y.; Navarra, F.S.

    1990-10-01

    Transverse-momentum distributions of π and K have been analysed to obtain the √s dependence of the collective transverse and the dissociation temperature in pp- and p-barp induced multiparticle production reactions. A good fit of both the pion and kaon data has been obtained in terms of a previously proposed simple parametrization of the collective transverse rapidity distribution. The main outcomes are the logarithmically increasing average transverse rapidity squared and a slowly decreasing dissociation temperature T sub(d) as the incident energy √s increases. This last behaviour is in excellent agreement with early Landau's estimate. An extension of the same estimate to nucleus-nucleus collisions gives the correct low temperature component which has been observed in heavy-ion experiments. (author)

  7. Dissociation dynamics of methylal

    Energy Technology Data Exchange (ETDEWEB)

    Beaud, P; Frey, H -M; Gerber, T; Mischler, B; Radi, P P; Tzannis, A -P [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The dissociation of methylal is investigated using mass spectrometry, combined with a pyrolytic radical source and femtosecond pump probe experiments. Based on preliminary results two reaction paths of methylal dissociation are proposed and discussed. (author) 4 fig., 3 refs.

  8. A method for measurements of neutral fragments kinetic energies released to a specific dissociation threshold: optical translational spectroscopy

    International Nuclear Information System (INIS)

    Roney, A.; Frigon, C.; Larzilliere, M.

    1999-01-01

    The optical translational spectroscopy technique, based on the principles of fast ion beam laser spectroscopy (FIBLAS) and translational spectroscopy, allows the kinetic energies study of neutral fragments released through free dissociation of a neutral molecule. This method presents interesting features such as near-threshold energy measurements and selection of a specific dissociation limit. The fragments resulting from free dissociation (not induced) of neutral molecules, produced by charge exchange processes with a fast ion beam, are probed by laser radiation. Monitoring of the laser-induced fluorescence allows high-resolution spectra due to the kinematic compression of the velocity spread. Measurements of kinetic energies released to the second limit of dissociation H(1s) + H(2l) of H 2 are put forth and compared with those obtained by means of off-axis translational spectroscopy

  9. Collisional Dissociation of CO: ab initio Potential Energy Surfaces and Quasiclassical Trajectory Rate Coefficients

    Science.gov (United States)

    Schwenke, David W.; Jaffe, Richard L.; Chaban, Galina M.

    2016-01-01

    We have generated accurate global potential energy surfaces for CO+Ar and CO+O that correlate with atom-diatom pairs in their ground electronic states based on extensive ab initio electronic structure calculations and used these potentials in quasi-classical trajectory nuclear dynamics calculations to predict the thermal dissociation rate coefficients over 5000- 35000 K. Our results are not compatible with the 20-45 year old experimental results. For CO + Ar we obtain fairly good agreement with the experimental rate coefficients of Appleton et al. (1970) and Mick and Roth (1993), but our computed rate coefficients exhibit a stronger temperature dependence. For CO + O our dissociation rate coefficient is in close agreement with the value from the Park model, which is an empirical adjustment of older experimental results. However, we find the rate coefficient for CO + O is only 1.5 to 3.3 times larger than CO + Ar over the temperature range of the shock tube experiments (8000-15,000 K). The previously accepted value for this rate coefficient ratio is 15, independent of temperature. We also computed the rate coefficient for the CO + O ex- change reaction which forms C + O2. We find this reaction is much faster than previously believed and is the dominant process in the removal of CO at temperatures up to 16,000 K. As a result, the dissociation of CO is accomplished in two steps (react to form C+O2 and then O2 dissociates) that are endothermic by 6.1 and 5.1 eV, instead of one step that requires 11.2 eV to break the CO bond.

  10. Energy-sensitive imaging detector applied to the dissociative recombination of D2H+

    International Nuclear Information System (INIS)

    Buhr, H.; Schwalm, D.; Mendes, M. B.; Novotny, O.; Berg, M. H.; Bing, D.; Krantz, C.; Orlov, D. A.; Sorg, T.; Stuetzel, J.; Varju, J.; Wolf, A.; Heber, O.; Rappaport, M. L.; Zajfman, D.

    2010-01-01

    We report on an energy-sensitive imaging detector for studying the fragmentation of polyatomic molecules in the dissociative recombination of fast molecular ions with electrons. The system is based on a large area (10x10 cm 2 ) position-sensitive, double-sided Si-strip detector with 128 horizontal and 128 vertical strips, whose pulse height information is read out individually. The setup allows us to uniquely identify fragment masses and is thus capable of measuring branching ratios between different fragmentation channels, kinetic energy releases, and breakup geometries as a function of the relative ion-electron energy. The properties of the detection system, which has been installed at the Test Storage Ring (TSR) facility of the Max-Planck Institute for Nuclear Physics in Heidelberg, is illustrated by an investigation of the dissociative recombination of the deuterated triatomic hydrogen cation D 2 H + . A huge isotope effect is observed when comparing the relative branching ratio between the D 2 + H and the HD + D channel; the ratio 2B(D 2 + H)/B(HD + D), which is measured to be 1.27±0.05 at relative electron-ion energies around 0 eV, is found to increase to 3.7±0.5 at ∼5 eV.

  11. Energy-sensitive imaging detector applied to the dissociative recombination of D2H+

    Science.gov (United States)

    Buhr, H.; Mendes, M. B.; Novotný, O.; Schwalm, D.; Berg, M. H.; Bing, D.; Heber, O.; Krantz, C.; Orlov, D. A.; Rappaport, M. L.; Sorg, T.; Stützel, J.; Varju, J.; Wolf, A.; Zajfman, D.

    2010-06-01

    We report on an energy-sensitive imaging detector for studying the fragmentation of polyatomic molecules in the dissociative recombination of fast molecular ions with electrons. The system is based on a large area (10×10 cm2) position-sensitive, double-sided Si-strip detector with 128 horizontal and 128 vertical strips, whose pulse height information is read out individually. The setup allows us to uniquely identify fragment masses and is thus capable of measuring branching ratios between different fragmentation channels, kinetic energy releases, and breakup geometries as a function of the relative ion-electron energy. The properties of the detection system, which has been installed at the Test Storage Ring (TSR) facility of the Max-Planck Institute for Nuclear Physics in Heidelberg, is illustrated by an investigation of the dissociative recombination of the deuterated triatomic hydrogen cation D2H+. A huge isotope effect is observed when comparing the relative branching ratio between the D2 + H and the HD + D channel; the ratio 2B(D2 + H)/B(HD + D), which is measured to be 1.27±0.05 at relative electron-ion energies around 0 eV, is found to increase to 3.7±0.5 at ~5 eV.

  12. Transition probabilities and dissociation energies of MnH and MnD molecules

    International Nuclear Information System (INIS)

    Nagarajan, K.; Rajamanickam, N.

    1997-01-01

    The Frank-Condon factors (vibrational transition probabilities) and r-centroids have been evaluated by the more reliable numerical integration procedure for the bands of A-X system of MnH and MnD molecules, using a suitable potential. By fitting the Hulburt- Hirschfelder function to the experimental potential curve using correlation coefficient, the dissociation energy for the electronic ground states of MnH and MnD molecules, respectively have been estimated as D 0 0 =251±5 KJ.mol -1 and D 0 0 =312±6 KJ.mol -1 . (authors)

  13. Energy-dependent dissociation of ATP from high affinity catalytic sites of beef heart mitochondrial adenosine triphosphatase

    International Nuclear Information System (INIS)

    Penefsky, H.S.

    1985-01-01

    Incubation of [gamma- 32 P]ATP with a molar excess of the membrane-bound form of mitochondrial ATPase (F1) results in binding of the bulk of the radioactive nucleotide in high affinity catalytic sites (Ka = 10(12) M-1). Subsequent initiation of respiration by addition of succinate or NADH is accompanied by a profound decrease in the affinity for ATP. About one-third of the bound radioactive ATP appears to dissociate, that is, the [gamma- 32 P]ATP becomes accessible to hexokinase. The NADH-stimulated dissociation of [gamma- 32 P]ATP is energy-dependent since the stimulation is inhibited by uncouplers of oxidative phosphorylation and is prevented by respiratory chain inhibitors. The rate of the energy-dependent dissociation of ATP that occurs in the presence of NADH, ADP, and Pi is commensurate with the measured initial rate of ATP synthesis in NADH-supported oxidative phosphorylation catalyzed by the same submitochondrial particles. Thus, the rate of dissociation of ATP from the high affinity catalytic site of submitochondrial particles meets the criterion of kinetic competency under the conditions of oxidative phosphorylation. These experiments provide evidence in support of the argument that energy conserved during the oxidation of substrates by the respiratory chain can be utilized to reduce the very tight binding of product ATP in high affinity catalytic sites and to promote dissociation of the nucleotide

  14. Multiphoton ionization as a probe of molecular photofragmentation: statistical and dynamical energy partitioning in the multiphoton dissociation of nitromethane

    International Nuclear Information System (INIS)

    Rockney, B.H.

    1982-01-01

    Multiphoton ionization (MPI) appears in its first use as a probe of laser-induced photofragmentation. Specifically, MPI here reveals the internal and translational energy content of the nascent fragments from the infrared multiphoton dissociation (MPD) of nitromethane (CH 3 NO 2 ). The apparatus for this work consists of a pulsed supersonic molecular beam crossed by two pulsed and focused lasers - a CO 2 laser to induce collision-free unimolecular dissociation of CH 3 NO 2 , and a tunable dye laser following immediately to ionize selectively one of the pair of dissociation fragments for detection by a mass spectrometer and particle multiplier. A computer simulation of each fragment's MPI spectrum, a series of four photon resonances to members of the npsigma/sub u/ Rydberg state of NO 2 and three photon resonances to two vibrational members of the #betta# 1 Rydberg state of CH 3 , aids in determining the fragment's internal energy content. The dye laser is delayed and its focus is traced through a small quarter circle centered at the focus of the CO 2 laser. The flight times of the fragments from the point of dissociation and their laboratory scattering angular distributions at fixed ionizing laser wavelength provide their center of mass recoil velocity distributions. The energy deposited in the fragments evidences a striking mixture of statistical and dynamical energy partitioning. The statistical RRKM theory of unimolecular decomposition accurately predicts the amount of internal energy found in the fragments

  15. Feasibility of large-scale phosphoproteomics with higher energy collisional dissociation fragmentation

    DEFF Research Database (Denmark)

    Nagaraj, Nagarjuna; D'Souza, Rochelle C J; Cox, Juergen

    2010-01-01

    Mass spectrometry (MS)-based proteomics now enables the analysis of thousands of phosphorylation sites in single projects. Among a wide range of analytical approaches, the combination of high resolution MS scans in an Orbitrap analyzer with low resolution MS/MS scans in a linear ion trap has proven......-scale phosphoproteome analysis alongside collisional induced dissociation, (CID) and electron capture/transfer dissociation (ECD/ETD)....

  16. D2 dissociative adsorption on and associative desorption from Si(100): Dynamic consequences of an ab initio potential energy surface

    DEFF Research Database (Denmark)

    Luntz, A. C.; Kratzer, Peter

    1996-01-01

    favors the symmetric one. Under the conditions of many experiments, either could dominate. The calculations show quite weak dynamic coupling to the Si lattice for both paths, i.e., weak surface temperature dependences to dissociation and small energy loss to the lattice upon desorption......Dynamical calculations are reported for D-2 dissociative chemisorption on and associative desorption from a Si(100) surface. These calculations use the dynamically relevant effective potential which is based on an ab initio potential energy surface for the ''pre-paired'' species. Three coordinates...

  17. Free energy landscape of dissociative adsorption of methane on ideal and defected graphene from ab initio simulations

    Science.gov (United States)

    Wlazło, M.; Majewski, J. A.

    2018-03-01

    We study the dissociative adsorption of methane at the surface of graphene. Free energy profiles, which include activation energies for different steps of the reaction, are computed from constrained ab initio molecular dynamics. At 300 K, the reaction barriers are much lower than experimental bond dissociation energies of gaseous methane, strongly indicating that the graphene surface acts as a catalyst of methane decomposition. On the other hand, the barriers are still much higher than on the nickel surface. Methane dissociation therefore occurs at a higher rate on nickel than on graphene. This reaction is a prerequisite for graphene growth from a precursor gas. Thus, the growth of the first monolayer should be a fast and efficient process while subsequent layers grow at a diminished rate and in a more controllable manner. Defects may also influence reaction energetics. This is evident from our results, in which simple defects (Stone-Wales defect and nitrogen substitution) lead to different free energy landscapes at both dissociation and adsorption steps of the process.

  18. Dissociation of the effects of preload volume and energy content on subjective appetite and food intake.

    Science.gov (United States)

    Gray, Richard; French, Stephen; Robinson, Tristan; Yeomans, Martin

    2002-05-01

    Previous research suggests that enhancing the volume of a food preload without altering energy content can result in reduced appetite, although the limited evidence means that the conditions under which this effect will occur are not yet clear. In the present study, we used a Universal Eating Monitor (UEM) to record test meal intake constantly, in parallel with appetite ratings, following soup-based preloads that varied both in volume (150 vs. 450 ml) and energy density (1.4 vs. 4.2 kJ/ml). Healthy young men (n=20) received four different preload conditions (repeated measures) followed by unlimited hot pasta test meals (interval 30 min). They completed appetite ratings during and after each laboratory session, and food diaries for the afternoon and evening following each session. Subjective appetite after the preloads was reduced by the high-volume preloads relative to low-volume preloads, with no difference between the two at each volume level. This indicates an effect of volume, but no effect of energy. Test meal intake in the high-volume, high-energy-density condition was reduced relative to the other conditions, which did not differ from one another. This indicates an effect of total energy, but no effect of volume. The dissociation between these different measures of appetite might be explained in terms of largely cognitive influences on subjective appetite between preload and test meal, contrasted with stronger physiological influences on actual intake during the test meal. With regard to previous studies, it is argued that food volume is more influential under circumstances where gastric volume is closer to its normal limits.

  19. Dissociative recombination of dications

    International Nuclear Information System (INIS)

    Seiersen, K.; Heber, O.; Jensen, M.J.; Safvan, C.P.; Andersen, L. H.

    2003-01-01

    Dissociative recombination (DR) of doubly-charged positive ions has been studied at the heavy ion storage ring ASTRID. Low-energy electrons were scattered on the dication of the N 2 molecule, and the absolute cross section was measured in the energy range of 10 -4 -50 eV. From the measured cross section, a thermal rate coefficient of 5.8x10 -7 cm 3 s -1 at 300 K was extracted. Furthermore, we present new results on the CO 2+ DR rate, and a summary and comparison of measured DR rate coefficients for both the singly and doubly-charged ions of CO, CO 2 , and N 2 is presented

  20. Increasing the productivity of glycopeptides analysis by using higher-energy collision dissociation-accurate mass-product-dependent electron transfer dissociation.

    Science.gov (United States)

    Saba, Julian; Dutta, Sucharita; Hemenway, Eric; Viner, Rosa

    2012-01-01

    Currently, glycans are attracting attention from the scientific community as potential biomarkers or as posttranslational modifications (PTMs) of therapeutic proteins. However, structural characterization of glycoproteins and glycopeptides remains analytically challenging. Here, we report on the implementation of a novel acquisition strategy termed higher-energy collision dissociation-accurate mass-product-dependent electron transfer dissociation (HCD-PD-ETD) on a hybrid linear ion trap-orbitrap mass spectrometer. This acquisition strategy uses the complementary fragmentations of ETD and HCD for glycopeptides analysis in an intelligent fashion. Furthermore, the approach minimizes user input for optimizing instrumental parameters and enables straightforward detection of glycopeptides. ETD spectra are only acquired when glycan oxonium ions from MS/MS HCD are detected. The advantage of this approach is that it streamlines data analysis and improves dynamic range and duty cycle. Here, we present the benefits of HCD-PD-ETD relative to the traditional alternating HCD/ETD for a trainer set containing twelve-protein mixture with two glycoproteins: human serotransferrin, ovalbumin and contaminations of two other: bovine alpha 1 acid glycoprotein (bAGP) and bovine fetuin.

  1. Principal component analysis acceleration of rovibrational coarse-grain models for internal energy excitation and dissociation

    Science.gov (United States)

    Bellemans, Aurélie; Parente, Alessandro; Magin, Thierry

    2018-04-01

    The present work introduces a novel approach for obtaining reduced chemistry representations of large kinetic mechanisms in strong non-equilibrium conditions. The need for accurate reduced-order models arises from compression of large ab initio quantum chemistry databases for their use in fluid codes. The method presented in this paper builds on existing physics-based strategies and proposes a new approach based on the combination of a simple coarse grain model with Principal Component Analysis (PCA). The internal energy levels of the chemical species are regrouped in distinct energy groups with a uniform lumping technique. Following the philosophy of machine learning, PCA is applied on the training data provided by the coarse grain model to find an optimally reduced representation of the full kinetic mechanism. Compared to recently published complex lumping strategies, no expert judgment is required before the application of PCA. In this work, we will demonstrate the benefits of the combined approach, stressing its simplicity, reliability, and accuracy. The technique is demonstrated by reducing the complex quantum N2(g+1Σ) -N(S4u ) database for studying molecular dissociation and excitation in strong non-equilibrium. Starting from detailed kinetics, an accurate reduced model is developed and used to study non-equilibrium properties of the N2(g+1Σ) -N(S4u ) system in shock relaxation simulations.

  2. Energy redistribution in the dissociation of low Rydberg states of HeH and 02

    International Nuclear Information System (INIS)

    Zande, W.J.A. van der.

    1988-01-01

    In this thesis the dissocation process is studied of the diatomic molecules, heliumhydride and molecular oxygen. In ch.'s 2-4 results on the spectroscopy and dissociative decay of the excited states of heliumhydride (HeH) are explained. The positions and dissociation pathways of the A 2 Σ + and B 2 Π states are determined and a theoretical description of the decay of these states are given. An isotope dependent dissociation behaviour of the C 2 /σ + Rydberg state is reported which explained with this theory. In ch.'s 5-7 observations are presented regarding the first Rydberg states of molecular oxygen. The spectroscopy of the (3sσ)d 1 Π g and C 3 Π g states is treated, and the stability and decay of these Rydberg states is discussed qualitatively. An experimental study is described of the (3sσ)d 1 Π g , v=4-8 states. By isotope studies and resolving rotational lines and the measurements of natural linewidths quantitative estimates have been acquired on coupling strengths, positions of repulsive valence states and perturbations reported in literature from REMPI experiments. The electronic coupling strengths between the C 3 Π g state and the 3 Π g valence state has been established. Observed spin-orbit interactions have been quantified and the dissociation of the multiplet states (C 3 Π g , ω=0-2 has been correlated with the multiplet states of the fragment O 3 P J=0-2 . The spectroscopy of the (3sσ3) Rydberg states which con- verge to and are formed in collisions with the O + 2 , a 4 Π μ ion state, is treated. The (3sσ) 5 /π μ state competition between auto-ionizations and (pre-)dissociation has been observed. 207 refs.; 36 figs.; 18 tabs

  3. Vibrational analysis of HOCl up to 98% of the dissociation energy with a Fermi resonance Hamiltonian

    International Nuclear Information System (INIS)

    Jost, R.; Joyeux, M.; Skokov, S.; Bowman, J.

    1999-01-01

    We have analyzed the vibrational energies and wave functions of HOCl obtained from previous ab initio calculations [J. Chem. Phys. 109, 2662 (1998); 109, 10273 (1998)]. Up to approximately 13 and h;000 cm -1 , the normal modes are nearly decoupled, so that the analysis is straightforward with a Dunham model. In contrast, above 13 and h;000 cm -1 the Dunham model is no longer valid for the levels with no quanta in the OH stretch (v 1 =0). In addition to v 1 , these levels can only be assigned a so-called polyad quantum number P=2v 2 +v 3 , where 2 and 3 denote, respectively, the bending and OCl stretching normal modes. In contrast, the levels with v 1 ≥2 remain assignable with three v i quantum numbers up to the dissociation (D 0 =19 and h;290 and h;cm -1 ). The interaction between the bending and the OCl stretch (ω 2 congruent 2ω 3 ) is well described with a simple, fitted Fermi resonance Hamiltonian. The energies and wave functions of this model Hamiltonian are compared with those obtained from ab initio calculations, which in turn enables the assignment of many additional ab initio vibrational levels. Globally, among the 809 bound levels calculated below dissociation, 790 have been assigned, the lowest unassigned level, No. 736, being located at 18 and h;885 cm -1 above the (0,0,0) ground level, that is, at about 98% of D 0 . In addition, 84 resonances located above D 0 have also been assigned. Our best Fermi resonance Hamiltonian has 29 parameters fitted with 725 ab initio levels, the rms deviation being of 5.3 cm -1 . This set of 725 fitted levels includes the full set of levels up to No. 702 at 18 and h;650 cm -1 . The ab initio levels, which are assigned but not included in the fit, are reasonably predicted by the model Hamiltonian, but with a typical error of the order of 20 cm -1 . The classical analysis of the periodic orbits of this Hamiltonian shows that two bifurcations occur at 13 and h;135 and 14 and h;059 cm -1 for levels with v 1 =0. Above each

  4. Zero-Point Energy Constraint for Unimolecular Dissociation Reactions. Giving Trajectories Multiple Chances To Dissociate Correctly.

    Science.gov (United States)

    Paul, Amit K; Hase, William L

    2016-01-28

    A zero-point energy (ZPE) constraint model is proposed for classical trajectory simulations of unimolecular decomposition and applied to CH4* → H + CH3 decomposition. With this model trajectories are not allowed to dissociate unless they have ZPE in the CH3 product. If not, they are returned to the CH4* region of phase space and, if necessary, given additional opportunities to dissociate with ZPE. The lifetime for dissociation of an individual trajectory is the time it takes to dissociate with ZPE in CH3, including multiple possible returns to CH4*. With this ZPE constraint the dissociation of CH4* is exponential in time as expected for intrinsic RRKM dynamics and the resulting rate constant is in good agreement with the harmonic quantum value of RRKM theory. In contrast, a model that discards trajectories without ZPE in the reaction products gives a CH4* → H + CH3 rate constant that agrees with the classical and not quantum RRKM value. The rate constant for the purely classical simulation indicates that anharmonicity may be important and the rate constant from the ZPE constrained classical trajectory simulation may not represent the complete anharmonicity of the RRKM quantum dynamics. The ZPE constraint model proposed here is compared with previous models for restricting ZPE flow in intramolecular dynamics, and connecting product and reactant/product quantum energy levels in chemical dynamics simulations.

  5. Full Wave Function Optimization with Quantum Monte Carlo and Its Effect on the Dissociation Energy of FeS.

    Science.gov (United States)

    Haghighi Mood, Kaveh; Lüchow, Arne

    2017-08-17

    Diffusion quantum Monte Carlo calculations with partial and full optimization of the guide function are carried out for the dissociation of the FeS molecule. For the first time, quantum Monte Carlo orbital optimization for transition metal compounds is performed. It is demonstrated that energy optimization of the orbitals of a complete active space wave function in the presence of a Jastrow correlation function is required to obtain agreement with the experimental dissociation energy. Furthermore, it is shown that orbital optimization leads to a 5 Δ ground state, in agreement with experiments but in disagreement with other high-level ab initio wave function calculations which all predict a 5 Σ + ground state. The role of the Jastrow factor in DMC calculations with pseudopotentials is investigated. The results suggest that a large Jastrow factor may improve the DMC accuracy substantially at small additional cost.

  6. Collision-induced dissociation of diatomic ions

    International Nuclear Information System (INIS)

    Los, J.; Govers, T.R.

    1978-01-01

    An attempt is made to illustrate how mass spectrometric studies of dissociation in diatomic molecular ions can provide information on the dynamics of these collisions and on the predissociative states involved. Restriction is made to primary beam energies of the order of at least keV. The review covers the dynamics of dissociation, experimental techniques, direct dissociation in heavy-particle collisions, and translational spectroscopy. 120 references

  7. Spatial and energy distributions of the fragments resulting from the dissociation of swift molecular ions in solids

    International Nuclear Information System (INIS)

    Heredia-Avalos, Santiago; Garcia-Molina, Rafael; Abril, Isabel

    2002-01-01

    We have simulated the spatial evolution and energy loss of the fragments that result when swift molecular ions dissociate inside solid targets. In our calculations we have considered that these fragments undergo the following interactions: Coulomb repulsion (among like charged particles), stopping and wake forces (due to electronic excitations induced in the target), and nuclear scattering (with the target nuclei). We study the case of silicon targets irradiated with boron molecular or atomic ions; our results show that the main differences in the energy and spatial distributions of molecular fragments or atomic ions appear at shallow regions, and these tend to disappear at deeper depths

  8. Dissociative scattering of low-energy SiF{sub 3}{sup +} and SiF{sup +} ions (5-200 eV) on Cu(100) surface

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Hiroyuki; Baba, Yuji; Sasaki, T A [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    Dissociative scattering of molecular SiF{sub 3}{sup +} and SiF{sup +} ions from a Cu(100) single crystal surface has been investigated in the incident energy range from 5 eV to 200 eV with a scattering angle of 77deg. The scattered ion intensity of dissociative ions and parent molecular ions were measured as a function of incident ion energy. The observed data show that onset energies of dissociation for SiF{sub 3}{sup +} and SiF{sup +} ions are 30 eV and 40 eV, respectively. The obtained threshold energies are consistent with a impulsive collision model where the dissociation of incident ion is caused by vibrational excitation during collision. (author)

  9. Neurophysiological correlates of dissociative symptoms

    NARCIS (Netherlands)

    Kruijs, van der S.J.M.; Bodde, N.M.G; Carrette, E.C.B.; Lazeron, R.H.C; Vonck, K.E.J.; Boon, P.A.J.M.; Langereis, G.R.; Cluitmans, P.J.M.; Feijs, L.M.G.; Hofman, P.A.M.; Backes, W.H.; Jansen, J.F.A.; Aldenkamp, A.P.

    2014-01-01

    Objective: Dissociation is a mental process with psychological and somatoform manifestations, which is closely related to hypnotic suggestibility and essentially shows the ability to obtain distance from reality. An increased tendency to dissociate is a frequently reported characteristic of patients

  10. Dissociative Photoionization of Diethyl Ether.

    Science.gov (United States)

    Voronova, Krisztina; Mozaffari Easter, Chrissa M; Covert, Kyle J; Bodi, Andras; Hemberger, Patrick; Sztáray, Bálint

    2015-10-29

    The dissociative photoionization of internal energy selected diethyl ether ions was investigated by imaging photoelectron photoion coincidence spectroscopy. In a large, 5 eV energy range Et2O(+) cations decay by two parallel and three sequential dissociative photoionization channels, which can be modeled well using statistical theory. The 0 K appearance energies of the CH3CHOCH2CH3(+) (H-loss, m/z = 73) and CH3CH2O═CH2(+) (methyl-loss, m/z = 59) fragment ions were determined to be 10.419 ± 0.015 and 10.484 ± 0.008 eV, respectively. The reemergence of the hydrogen-loss ion above 11 eV is attributed to transition-state (TS) switching, in which the second, outer TS is rate-determining at high internal energies. At 11.81 ± 0.05 eV, a secondary fragment of the CH3CHOCH2CH3(+) (m/z = 73) ion, protonated acetaldehyde, CH3CH═OH(+) (m/z = 45) appears. On the basis of the known thermochemical onset of this fragment, a reverse barrier of 325 meV was found. Two more sequential dissociation reactions were examined, namely, ethylene and formaldehyde losses from the methyl-loss daughter ion. The 0 K appearance energies of 11.85 ± 0.07 and 12.20 ± 0.08 eV, respectively, indicate no reverse barrier in these processes. The statistical model of the dissociative photoionization can also be used to predict the fractional ion abundances in threshold photoionization at large temperatures, which could be of use in, for example, combustion diagnostics.

  11. Three dimensions of dissociative amnesia.

    Science.gov (United States)

    Dell, Paul F

    2013-01-01

    Principal axis factor analysis with promax rotation extracted 3 factors from the 42 memory and amnesia items of the Multidimensional Inventory of Dissociation (MID) database (N = 2,569): Discovering Dissociated Actions, Lapses of Recent Memory and Skills, and Gaps in Remote Memory. The 3 factors' shared variance ranged from 36% to 64%. Construed as scales, the 3 factor scales had Cronbach's alpha coefficients of .96, .94, and .93, respectively. The scales correlated strongly with mean Dissociative Experiences Scale scores, mean MID scores, and total scores on the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised (SCID-D-R). What is interesting is that the 3 amnesia factors exhibited a range of correlations with SCID-D-R Amnesia scores (.52, .63, and .70, respectively), suggesting that the SCID-D-R Amnesia score emphasizes gaps in remote memory over amnesias related to dissociative identity disorder. The 3 amnesia factor scales exhibited a clinically meaningful pattern of significant differences among dissociative identity disorder, dissociative disorder not otherwise specified-1, dissociative amnesia, depersonalization disorder, and nonclinical participants. The 3 amnesia factors may have greater clinical utility for frontline clinicians than (a) amnesia as discussed in the context of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, nosology of the dissociative disorders or (b) P. Janet's (1893/1977 ) 4-fold classification of dissociative amnesia. The author recommends systematic study of the phenomenological differences within specific dissociative symptoms and their differential relationship to specific dissociative disorders.

  12. Nascent energy distribution of the Criegee intermediate CH2OO from direct dynamics calculations of primary ozonide dissociation

    Science.gov (United States)

    Pfeifle, Mark; Ma, Yong-Tao; Jasper, Ahren W.; Harding, Lawrence B.; Hase, William L.; Klippenstein, Stephen J.

    2018-05-01

    Ozonolysis produces chemically activated carbonyl oxides (Criegee intermediates, CIs) that are either stabilized or decompose directly. This branching has an important impact on atmospheric chemistry. Prior theoretical studies have employed statistical models for energy partitioning to the CI arising from dissociation of the initially formed primary ozonide (POZ). Here, we used direct dynamics simulations to explore this partitioning for decomposition of c-C2H4O3, the POZ in ethylene ozonolysis. A priori estimates for the overall stabilization probability were then obtained by coupling the direct dynamics results with master equation simulations. Trajectories were initiated at the concerted cycloreversion transition state, as well as the second transition state of a stepwise dissociation pathway, both leading to a CI (H2COO) and formaldehyde (H2CO). The resulting CI energy distributions were incorporated in master equation simulations of CI decomposition to obtain channel-specific stabilized CI (sCI) yields. Master equation simulations of POZ formation and decomposition, based on new high-level electronic structure calculations, were used to predict yields for the different POZ decomposition channels. A non-negligible contribution of stepwise POZ dissociation was found, and new mechanistic aspects of this pathway were elucidated. By combining the trajectory-based channel-specific sCI yields with the channel branching fractions, an overall sCI yield of (48 ± 5)% was obtained. Non-statistical energy release was shown to measurably affect sCI formation, with statistical models predicting significantly lower overall sCI yields (˜30%). Within the range of experimental literature values (35%-54%), our trajectory-based calculations favor those clustered at the upper end of the spectrum.

  13. Nascent energy distribution of the Criegee intermediate CH2OO from direct dynamics calculations of primary ozonide dissociation.

    Science.gov (United States)

    Pfeifle, Mark; Ma, Yong-Tao; Jasper, Ahren W; Harding, Lawrence B; Hase, William L; Klippenstein, Stephen J

    2018-05-07

    Ozonolysis produces chemically activated carbonyl oxides (Criegee intermediates, CIs) that are either stabilized or decompose directly. This branching has an important impact on atmospheric chemistry. Prior theoretical studies have employed statistical models for energy partitioning to the CI arising from dissociation of the initially formed primary ozonide (POZ). Here, we used direct dynamics simulations to explore this partitioning for decomposition of c-C 2 H 4 O 3 , the POZ in ethylene ozonolysis. A priori estimates for the overall stabilization probability were then obtained by coupling the direct dynamics results with master equation simulations. Trajectories were initiated at the concerted cycloreversion transition state, as well as the second transition state of a stepwise dissociation pathway, both leading to a CI (H 2 COO) and formaldehyde (H 2 CO). The resulting CI energy distributions were incorporated in master equation simulations of CI decomposition to obtain channel-specific stabilized CI (sCI) yields. Master equation simulations of POZ formation and decomposition, based on new high-level electronic structure calculations, were used to predict yields for the different POZ decomposition channels. A non-negligible contribution of stepwise POZ dissociation was found, and new mechanistic aspects of this pathway were elucidated. By combining the trajectory-based channel-specific sCI yields with the channel branching fractions, an overall sCI yield of (48 ± 5)% was obtained. Non-statistical energy release was shown to measurably affect sCI formation, with statistical models predicting significantly lower overall sCI yields (∼30%). Within the range of experimental literature values (35%-54%), our trajectory-based calculations favor those clustered at the upper end of the spectrum.

  14. Dissociation of ethane by electron impact

    International Nuclear Information System (INIS)

    Winters, H.F.

    1979-01-01

    The absolute total dissociation cross section for ethane is reported for electron energies between 10 and 600 eV. A maximum value of 7.6 X 10 -16 cm 2 occurs at 80 eV while the apparent threshold is approximately 10 eV. Dissociative ionization is more probable than dissociation into neutral fragments at all energies except in the threshold region. The data indicates that fragmentation involving methane elimination (e - +C 2 H 6 → CH 4 + CH 2 ) occurs in less than 2% of the dissociative events for 50 < E < 600 eV. Arguments are presented which suggest that some of the lower excited states of ethane are stable against dissociation. (Auth.)

  15. Exit angle, energy loss and internuclear distance distributions of H2+ ions dissociated when traversing different materials

    International Nuclear Information System (INIS)

    Garcia-Molina, Rafael; Abril, Isabel; Denton, Cristian D.; Arista, Nestor R.

    2000-01-01

    We have performed computer simulations of the trajectory followed by each proton resulting from the dissociation of H 2 + molecules when traversing a thin solid target. We use the dielectric formalism to describe the forces due to electronic excitations in the medium, and we also consider the Coulomb repulsion between the pair of protons. Nuclear collisions with target nuclei are incorporated through a Monte Carlo code and the effect of the coherent scattering is taken into account by means of an effective force model. The distributions of exit angle, energy loss and internuclear separations of the protons fragments are discussed for the case of amorphous carbon and aluminum targets

  16. Seniority number description of potential energy surfaces: Symmetric dissociation of water, N2, C2, and Be2

    International Nuclear Information System (INIS)

    Bytautas, Laimutis; Scuseria, Gustavo E.; Ruedenberg, Klaus

    2015-01-01

    The present study further explores the concept of the seniority number (Ω) by examining different configuration interaction (CI) truncation strategies in generating compact wave functions in a systematic way. While the role of Ω in addressing static (strong) correlation problem has been addressed in numerous previous studies, the usefulness of seniority number in describing weak (dynamic) correlation has not been investigated in a systematic way. Thus, the overall objective in the present work is to investigate the role of Ω in addressing also dynamic electron correlation in addition to the static correlation. Two systematic CI truncation strategies are compared beyond minimal basis sets and full valence active spaces. One approach is based on the seniority number (defined as the total number of singly occupied orbitals in a determinant) and another is based on an excitation-level limitation. In addition, molecular orbitals are energy-optimized using multiconfigurational-self-consistent-field procedure for all these wave functions. The test cases include the symmetric dissociation of water (6-31G), N 2 (6-31G), C 2 (6-31G), and Be 2 (cc-pVTZ). We find that the potential energy profile for H 2 O dissociation can be reasonably well described using only the Ω = 0 sector of the CI wave function. For the Be 2 case, we show that the full CI potential energy curve (cc-pVTZ) is almost exactly reproduced using either Ω-based (including configurations having up to Ω = 2 in the virtual-orbital-space) or excitation-based (up to single-plus-double-substitutions) selection methods, both out of a full-valence-reference function. Finally, in dissociation cases of N 2 and C 2 , we shall also consider novel hybrid wave functions obtained by a union of a set of CI configurations representing the full valence space and a set of CI configurations where seniority-number restriction is imposed for a complete set (full-valence-space and virtual) of correlated molecular orbitals

  17. Communication: The highest frequency hydrogen bond vibration and an experimental value for the dissociation energy of formic acid dimer

    DEFF Research Database (Denmark)

    Kollipost, F.; Larsen, René Wugt; Domanskaya, A.V.

    2012-01-01

    The highest frequency hydrogen bond fundamental of formic acid dimer, ν24 (Bu), is experimentally located at 264 cm−1. FTIR spectra of this in-plane bending mode of (HCOOH)2 and band centers of its symmetric D isotopologues (isotopomers) recorded in a supersonic slit jet expansion are presented...... thermodynamics treatment of the dimerization process up to room temperature. We obtain D0 = 59.5(5) kJ/mol as the best experimental estimate for the dimer dissociation energy at 0 K. Further improvements have to wait for a more consistent determination of the room temperature equilibrium constant....

  18. Wavepacket theory of collisional dissociation in molecules

    International Nuclear Information System (INIS)

    Kulander, K.

    1980-01-01

    An explicit integration scheme is used to solve the time dependent Schroedinger equation for wavepackets which model collisions in the collinear H + H 2 system. A realistic LEPS-type potential energy surface is used. Collision energies considered are above the dissociation threshold and probabilities for collision induced dissociation are reported. Also quantum mechanical state-to-state transition probabilities are generated. These results are compared to extensive classical trajectory calculations performed on this same system. The time evolution of the wavepacket densities is studied to understand the dynamics of the collinear collisional dissociation process

  19. Inflight dissociation of zircon in air plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S; Selvarajan, V [Bharathiar University, Coimbatore 641046 (India); Ananthapadmanabhan, P V; Thiyagarajan, T K [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai - 400 085 (India); Nair, Janardhanan [Ion Arc Technologies Pvt Ltd, Coimbatore (India)

    2010-02-01

    Thermal dissociation of zircon can be conveniently carried out in a plasma reactor, which is characterized by high temperature, high energy density and high quench rate. Zirconia is recovered from this partially dissociated zircon by alkali leaching. Dissociation of zircon has been conventionally carried out in argon gas, which is expensive. The present paper reports experimental results on thermal dissociation of zircon in air plasma medium. Process simulation for 'inflight' dissociation of zircon in air plasma medium is also presented. The experimental system consists of a central hollow graphite electrode, which acts as the cathode and a graphite anode. The material to be processed is fed centrally through the cathode. The unique feature of the system is that it uses air as the working gas to generate the thermal plasma. The system has been used to study in-flight dissociation of zircon in the thermal plasma jet. Dissociation was carried out over 10-25 kW power range. Results of the study indicate that complete dissociation of zircon to ZrO{sub 2} and silica could be accomplished at 25 kW in air plasma.

  20. Inflight dissociation of zircon in air plasma

    International Nuclear Information System (INIS)

    Yugeswaran, S; Selvarajan, V; Ananthapadmanabhan, P V; Thiyagarajan, T K; Nair, Janardhanan

    2010-01-01

    Thermal dissociation of zircon can be conveniently carried out in a plasma reactor, which is characterized by high temperature, high energy density and high quench rate. Zirconia is recovered from this partially dissociated zircon by alkali leaching. Dissociation of zircon has been conventionally carried out in argon gas, which is expensive. The present paper reports experimental results on thermal dissociation of zircon in air plasma medium. Process simulation for 'inflight' dissociation of zircon in air plasma medium is also presented. The experimental system consists of a central hollow graphite electrode, which acts as the cathode and a graphite anode. The material to be processed is fed centrally through the cathode. The unique feature of the system is that it uses air as the working gas to generate the thermal plasma. The system has been used to study in-flight dissociation of zircon in the thermal plasma jet. Dissociation was carried out over 10-25 kW power range. Results of the study indicate that complete dissociation of zircon to ZrO 2 and silica could be accomplished at 25 kW in air plasma.

  1. Dissociative recombination of molecular ions H2+

    International Nuclear Information System (INIS)

    Abarenov, A.V.; Marchenko, V.S.

    1989-01-01

    The total cross sections of dissociation and dissociative recombination of slow electrons and molecular ions H 2 + have been calculated in terms of the quasiclassical and dipole approximations. In the calculations allowance was made for the quantum nature of vibrational motion of heavy particles and presence of autoionization of divergence states of the H 2 (Σ u , nl) molecules. It is shown that the H 2 + ion dissociation cross sections are dominant in increase of the electron energy in the ε >or approx. 2-3 eV region for H 2 + (v) ion distribution over the vibrational levels characteristic for the beam experiments. 15 refs.; 5 figs

  2. Ab initio calculations of dissociative excitation of water and methane molecules upon electron impact at low energies

    International Nuclear Information System (INIS)

    Gil, T.J.; McCurdy, C.W.; Rescigno, T.N.; Lengsfield, B.H. III

    1994-01-01

    The authors are reporting results of ab-initio calculations of electron-impact excitation of water and methane occurring at scattering energies up to 60 eV. The authors consider dissociative excited states of both systems since the understanding of their chemistry has considerable importance in plasma technology and atmospheric research. In the case of methane the authors are dealing with the promotion of a valence electron into Rydberg orbitals, while in water the excited states have one electron in an antibonding unoccupied valence orbital and support Feshbach resonances. The authors discuss issues related to convergence of the close-coupling expansion in the case of Rydberg excitation, where the authors have coupled up to 16 channels. The practical realization of the calculation within the framework of the complex Kohn variational principle represents merging of quantum chemistry and quantum scattering theory and is also discussed

  3. Dynamics of NO2 dissociation. Study by resonance-enhanced multi-photon ionisation of energy distribution and of anisotropies in fragments

    International Nuclear Information System (INIS)

    Mons, Michel

    1988-01-01

    In this research thesis, the author reports the use of laser resonance-enhanced multi-photon ionization and of time-of-flight mass spectrometry for a detailed characterization of fragments produced by a photo-dissociation process. The author more particularly addressed the case of a NO 2 molecule excited at low energies above the dissociation threshold. In the first part, the author discusses issues and problems related to molecular photo-dissociation. In the second part, he presents the developed method and shows that the combined use of both techniques allows a precise characterisation of photo-fragments in terms of internal or translational energies as well as in terms of angle distributions. Finally, the author presents and discusses results obtained in the case of NO 2 [fr

  4. Dissociation and decay of ultracold sodium molecules

    International Nuclear Information System (INIS)

    Mukaiyama, T.; Abo-Shaeer, J.R.; Xu, K.; Chin, J.K.; Ketterle, W.

    2004-01-01

    The dissociation of ultracold molecules was studied by ramping an external magnetic field through a Feshbach resonance. The observed dissociation energies directly yielded the strength of the atom-molecule coupling. They showed nonlinear dependence on the ramp speed. This was explained by a Wigner threshold law which predicts that the decay rate of the molecules above threshold increases with the density of states. In addition, inelastic molecule-molecule and molecule-atom collisions were characterized

  5. Low-energy electron-induced dissociation in condensed-phase L-cysteine I: Desorption of anions from chemisorbed films

    International Nuclear Information System (INIS)

    Alizadeh, E; Rowntree, P A; Massey, S; Sanche, L

    2015-01-01

    Among amino acids, cysteine has been widely studied, becoming a standard for molecular self-assembly experiments, because its mercapto group (-SH) allows the formation of self-assembled monolayers (SAMs) on metal surfaces. Dissociative electron attachment (DEA) on L-cysteine SAMs is investigated utilizing a time-of-flight mass spectrometer coupled with a low-energy electron gun. The results show that electrons with kinetic energies of 3 to 15 eV attach to L-cysteine producing anionic fragments of different masses (e.g., H - , O - , OH - , S - , SH - ) via dissociation of intermediate transient anions. The anion yield functions exhibited purely resonant behaviour with electron energies below 15 eV, indicating that the formation of transient anions is the predominant mechanism of production of anionic fragments from L-cysteine dissociation. (paper)

  6. Influence of Electron Molecule Resonant Vibrational Collisions over the Symmetric Mode and Direct Excitation-Dissociation Cross Sections of CO2 on the Electron Energy Distribution Function and Dissociation Mechanisms in Cold Pure CO2 Plasmas.

    Science.gov (United States)

    Pietanza, L D; Colonna, G; Laporta, V; Celiberto, R; D'Ammando, G; Laricchiuta, A; Capitelli, M

    2016-05-05

    A new set of electron-vibrational (e-V) processes linking the first 10 vibrational levels of the symmetric mode of CO2 is derived by using a decoupled vibrational model and inserted in the Boltzmann equation for the electron energy distribution function (eedf). The new eedf and dissociation rates are in satisfactory agreement with the corresponding ones obtained by using the e-V cross sections reported in the database of Hake and Phelps (H-P). Large differences are, on the contrary, found when the experimental dissociation cross sections of Cosby and Helm are inserted in the Boltzman equation. Comparison of the corresponding rates with those obtained by using the low-energy threshold energy, reported in the H-P database, shows differences up to orders of magnitude, which decrease with the increasing of the reduced electric field. In all cases, we show the importance of superelastic vibrational collisions in affecting eedf and dissociation rates either in the direct electron impact mechanism or in the pure vibrational mechanism.

  7. Suppression of low-energy dissociative electron attachment in Fe(CO)5 upon clustering

    Czech Academy of Sciences Publication Activity Database

    Lengyel, Jozef; Papp, P.; Matejčík, Š.; Kočišek, Jaroslav; Fárník, Michal; Fedor, Juraj

    2017-01-01

    Roč. 8, č. 1 (2017), s. 2200-2207 ISSN 2190-4286 R&D Projects: GA ČR GA17-04844S; GA ČR(CZ) GA17-04068S; GA ČR GJ16-10995Y Grant - others:COST(XE) CM1301 Institutional support: RVO:61388955 Keywords : aggregation effects * FEBID * dissociative electron attachment Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.127, year: 2016

  8. An ab initio study of potential energy surfaces of CH 3COCN dissociation on the low-lying states

    Science.gov (United States)

    Ding, Wan-Jian; Fang, Wei-Hai; Liu, Ruo-Zhuang

    2002-01-01

    The C-CH 3 and C-CN bond dissociations of CH 3COCN on S 1 and T 1 surfaces are studied at the CAS(8,7)/cc-pVDZ level. The results show that the intersystem crossing from S 1 to T 1 is a favorable pathway of S 1 deactivation. Once on the T 1 surface, the system can dissociate adiabatically to CH3 ( X˜)+ OCCN ( X˜) or CN ( X˜)+ CH3CO ( X˜) , but the former has some preference over the latter. This mechanism is consistent with Cheng's presumption deduced from the experimental facts and theoretical considerations. A comparison with other asymmetrically substituted carbonyl compounds suggests that the selectivity of the α-bond cleavage is mainly dependent on the mechanism of dissociation.

  9. A multivariate relationship for the impact sensitivities of energetic N-nitrocompounds based on bond dissociation energy.

    Science.gov (United States)

    Li, Jinshan

    2010-02-15

    The ZPE-corrected N-NO(2) bond dissociation energies (BDEs(ZPE)) of a series of model N-nitrocompounds and typical energetic N-nitrocompounds have been calculated using density functional theory methods. Computed results show that using the 6-31G** basis set the UB3LYP calculated BDE(ZPE) is similar to the B3PW91 but is less than the UB3P86 and that for both UB3P86 and UB3PW91 methods the 6-31G(**) calculated BDE(ZPE) is close to the 6-31++G(**). For the series of model N-nitrocompounds it is drawn from the NBO analysis that at the UB3LYP/6-31G(**) level the order of BDE(ZPE) is not only in line with that of bond order but also with that of the energy gap between N-NO(2) bond and antibond orbitals. For the typical energetic N-nitrocompounds the impact sensitivity is strongly related to the BDE(ZPE) indeed, and based on the BDEs(ZPE) calculated at different density functional theory levels this work has established a good multivariate correlation of impact sensitivity with molecular parameters, which provides a method to address the sensitivity problem.

  10. Photo-dissociation of hydrogen passivated dopants in gallium arsenide

    International Nuclear Information System (INIS)

    Tong, L.; Larsson, J.A.; Nolan, M.; Murtagh, M.; Greer, J.C.; Barbe, M.; Bailly, F.; Chevallier, J.; Silvestre, F.S.; Loridant-Bernard, D.; Constant, E.; Constant, F.M.

    2002-01-01

    A theoretical and experimental study of the photo-dissociation mechanisms of hydrogen passivated n- and p-type dopants in gallium arsenide is presented. The photo-induced dissociation of the Si Ga -H complex has been observed for relatively low photon energies (3.48 eV), whereas the photo-dissociation of C As -H is not observed for photon energies up to 5.58 eV. This fundamental difference in the photo-dissociation behavior between the two dopants is explained in terms of the localized excitation energies about the Si-H and C-H bonds

  11. Comparative study between hadron and heavy ion dissociation at high energies

    International Nuclear Information System (INIS)

    El-Bakry, Y.M.N.; Abd-Elhalim, S.M.

    2002-01-01

    The present work deals with the dissociation of hadrons and heavy ions at high energies. In investigating hadron nucleus and nucleus-nucleus collisions, it is important to classify the experimental data, into two main classes; the coherent. and incoherent reactions. The coherent production is the main of our study. This process called electromagnetic dissociation (ED) and can be differentiate into coulomb dissociation (CD) and diffraction dissociation (DD). This work explains the experimental data of collisions of hadrons K± (70 GeV/c) and π(340 Gc V/c) and heavy ions 6 L i, 7 L i, 1 2C and1 6O at Dubna energies (3-4.5 A GeV/c)with emulsion target, in the frame of some models and theories which describe the mechanism of ED dissociation

  12. Higher energy dissociative electron attachment cross sections in sulfur dioxide

    International Nuclear Information System (INIS)

    Kurepa, M.; Pejcev, V.; Cadez, I.

    2000-01-01

    Experimental results of total electron attachment cross sections are presented with, for comparison, two additional sets of data, those of Orient and Srivastava and of Spyrou et al.. Both were normalized to present values of the first attachment peak at 4,6 eV, in order to show more clearly differences in cross section curve shapes. In fact, data of Orient and Srivastava are larger that the present ones for a factor of 2,82; while those of Spyrou et al. are higher only for 3,70 %. Both these sets of data, as well as those by Cadez et al., cover an incident electron energy range 3,40 - 9,40 eV. Electron attachment processes at energies higher that 9,40 eV have been in fact detected and measured in the same set of experiments that led to former publication of lower energy attachment processes by Cadez et al.. At that time in none of experiments, that could distinguished ionic species formed in dissociation attachment processes, was a sign of ions at incident electron energies exceeding 9,40 eV. That caused our ignorance toward processes detected and measured at higher incident electron energies, mainly since they were at least one order of magnitude lower that the two peaks at 4,6 eV and 7,3 eV, respectively. Without additional experiments, that include mass analysis of ionic species formed in dissociative electron attachment processes, it is not possible to give any sound explanation to causes of peaks at energies higher that 8,0 eV

  13. Observation of double-well potential of NaH C 1Σ+ state: Deriving the dissociation energy of its ground state.

    Science.gov (United States)

    Chu, Chia-Ching; Huang, Hsien-Yu; Whang, Thou-Jen; Tsai, Chin-Chun

    2018-03-21

    Vibrational levels (v = 6-42) of the NaH C 1 Σ + state including the inner and outer wells and the near-dissociation region were observed by pulsed optical-optical double resonance fluorescence depletion spectroscopy. The absolute vibrational quantum number is identified by comparing the vibrational energy difference of this experiment with the ab initio calculations. The outer well with v up to 34 is analyzed using the Dunham expansion and a Rydberg-Klein-Rees (RKR) potential energy curve is constructed. A hybrid double-well potential combined with the RKR potential, the ab initio calculation, and a long-range potential is able to describe the whole NaH C 1 Σ + state including the higher vibrational levels (v = 35-42). The dissociation energy of the NaH C 1 Σ + state is determined to be D e (C) = 6595.10 ± 5 cm -1 and then the dissociation energy of the NaH ground state D e (X) = 15 807.87 ± 5 cm -1 can be derived.

  14. Rovibrational internal energy transfer and dissociation of N2(1Σg+)-N(4S(u)) system in hypersonic flows.

    Science.gov (United States)

    Panesi, Marco; Jaffe, Richard L; Schwenke, David W; Magin, Thierry E

    2013-01-28

    A rovibrational collisional model is developed to study energy transfer and dissociation of N(2)((1)Σ(g)(+)) molecules interacting with N((4)S(u)) atoms in an ideal isochoric and isothermal chemical reactor. The system examined is a mixture of molecular nitrogen and a small amount of atomic nitrogen. This mixture, initially at room temperature, is heated by several thousands of degrees Kelvin, driving the system toward a strong non-equilibrium condition. The evolution of the population densities of each individual rovibrational level is explicitly determined via the numerical solution of the master equation for temperatures ranging from 5000 to 50,000 K. The reaction rate coefficients are taken from an ab initio database developed at NASA Ames Research Center. The macroscopic relaxation times, energy transfer rates, and dissociation rate coefficients are extracted from the solution of the master equation. The computed rotational-translational (RT) and vibrational-translational (VT) relaxation times are different at low heat bath temperatures (e.g., RT is about two orders of magnitude faster than VT at T = 5000 K), but they converge to a common limiting value at high temperature. This is contrary to the conventional interpretation of thermal relaxation in which translational and rotational relaxation timescales are assumed comparable with vibrational relaxation being considerable slower. Thus, this assumption is questionable under high temperature non-equilibrium conditions. The exchange reaction plays a very significant role in determining the dynamics of the population densities. The macroscopic energy transfer and dissociation rates are found to be slower when exchange processes are neglected. A macroscopic dissociation rate coefficient based on the quasi-stationary distribution, exhibits excellent agreement with experimental data of Appleton et al. [J. Chem. Phys. 48, 599-608 (1968)]. However, at higher temperatures, only about 50% of dissociation is found to

  15. Dissociative charge exchange of H2+

    International Nuclear Information System (INIS)

    Bruijn, D. de.

    1983-01-01

    This thesis is devoted to molecular dissociation, in particular the dissociation of the hydrogen molecule H 2 arising from electron capture of its ion H 2 + in a collision. Thereby the important practical question how a chemical bond can be broken is implicitly addressed. This thesis opens (chapter I) with an overview of the available experimental approaches in molecular physics. Further the simple Demkov model for NRCE is described. In chapter II a novel experimental technique for measurements on dissociative processes is introduced which combines a high efficiency with a high energy resolution. A detailed description of the techniques applied in the detector, which has a high spatial and timing resolution with 30 μm and 350 psec FWHM respectively for the detection of one particle, is given in chapter III. A semi-classical theory for NRCE in the medium energy range between a diatomic molecular ion and an atom is developed in chapter IV. The experiments on dissociative charge exchange of H 2 + with Ar, Mg, Na and Cs targets at keV energies are described in Chapter V. The predissociation of the c 3 PIsub(u)-state of H 2 populated after charge exchange of H 2 with several targets at keV energies; is the subject of chapter VI. In chapter VII, orientational oscillations in the cross section for charge exchange of H 2 + with alkali targets are discussed. The last chapter deals with predissociation of highly excited states in H 2 . (Auth.)

  16. The O-H Bond Dissociation Energies of Substituted Phenols and Proton Affinities of Substituted Phenoxide Ions: A DFT Study

    Directory of Open Access Journals (Sweden)

    Tadafumi Uchimaru

    2002-04-01

    Full Text Available Abstract: The accurate O-H bond dissociation enthalpies for a series of meta and para substituted phenols (X-C6H4-OH, X=H, F, Cl, CH3, OCH3, OH, NH2, CF3, CN, and NO2 have been calculated by using the (ROB3LYP procedure with 6-311G(d,p and 6-311++G(2df,2p basis sets. The proton affinities of the corresponding phenoxide ions (XC6H4-O- have also been computed at the same level of theory. The effect of change of substituent position on the energetics of substituted phenols has been analyzed. The correlations of Hammett’s substituent constants with the bond dissociation enthalpies of the O-H bonds of phenols and proton affinities of phenoxide ions have been explored.

  17. Determination of metal-hydrogen bond dissociation energies by the deprotonation of transition metal hydride ions: application to MnH +

    Science.gov (United States)

    Stevens, Amy E.; Beauchamp, J. L.

    1981-03-01

    ICR trapped ion techniques are used to examine the kinetics of proton transfer from MnH + (formed as a fragment ion from HMn (CO) 5 by electron impact) to bases of varying strength. Deprotonation is rapid with bases whose proton affinity exceeds 196±3 kcal mol -1. This value for PA (Mn) yields the homolytic bond dissociation energy D0(Mn +-H) = 53±5 kcal mol -1.

  18. On the calculation of the energies of dissociation, cohesion, vacancy formation, electron attachment, and the ionization potential of small metallic clusters containing a monovacancy

    Science.gov (United States)

    Pogosov, V. V.; Reva, V. I.

    2017-09-01

    In terms of the model of stable jellium, self-consistent calculations of spatial distributions of electrons and potentials, as well as of energies of dissociation, cohesion, vacancy formation, electron attachment, and ionization potentials of solid clusters of Mg N , Li N (with N ≤ 254 ) and of clusters containing a vacancy ( N ≥ 12) have been performed. The contribution of a monovacancy to the energy of the cluster and size dependences of its characteristics and of asymptotics have been discussed. Calculations have been performed using a SKIT-3 cluster at Glushkov Institute of Cybernetics, National Academy of Sciences, Ukraine (Rpeak = 7.4 Tflops).

  19. Competition between dissociation paths of I2+ NO+ using fast laser fields

    International Nuclear Information System (INIS)

    Lev, U; Prabhudesai, V S; Natan, A; Schwalm, D; Bruner, B D; Silberberg, Y; Heber, O; Zajfman, D; Zohrabi, M; Gaire, B; Carnes, K D; Ben-Itzhak, I; Strasser, D

    2012-01-01

    The competition between dissociation paths of I 2 + and NO + molecules was studied using femtosecond laser pulses with different intensities. It was found, both for moderate fields and for strong fields, that the dissociation path strongly prefers the higher energy dissociation path with smaller kinetic energy rather than the lower energy path with higher kinetic energy.

  20. Calculation on spectrum of direct DNA damage induced by low-energy electrons including dissociative electron attachment.

    Science.gov (United States)

    Liu, Wei; Tan, Zhenyu; Zhang, Liming; Champion, Christophe

    2017-03-01

    In this work, direct DNA damage induced by low-energy electrons (sub-keV) is simulated using a Monte Carlo method. The characteristics of the present simulation are to consider the new mechanism of DNA damage due to dissociative electron attachment (DEA) and to allow determining damage to specific bases (i.e., adenine, thymine, guanine, or cytosine). The electron track structure in liquid water is generated, based on the dielectric response model for describing electron inelastic scattering and on a free-parameter theoretical model and the NIST database for calculating electron elastic scattering. Ionization cross sections of DNA bases are used to generate base radicals, and available DEA cross sections of DNA components are applied for determining DNA-strand breaks and base damage induced by sub-ionization electrons. The electron elastic scattering from DNA components is simulated using cross sections from different theoretical calculations. The resulting yields of various strand breaks and base damage in cellular environment are given. Especially, the contributions of sub-ionization electrons to various strand breaks and base damage are quantitatively presented, and the correlation between complex clustered DNA damage and the corresponding damaged bases is explored. This work shows that the contribution of sub-ionization electrons to strand breaks is substantial, up to about 40-70%, and this contribution is mainly focused on single-strand break. In addition, the base damage induced by sub-ionization electrons contributes to about 20-40% of the total base damage, and there is an evident correlation between single-strand break and damaged base pair A-T.

  1. Full-dimensional quantum calculations of the dissociation energy, zero-point, and 10 K properties of H7+/D7+ clusters using an ab initio potential energy surface.

    Science.gov (United States)

    Barragán, Patricia; Pérez de Tudela, Ricardo; Qu, Chen; Prosmiti, Rita; Bowman, Joel M

    2013-07-14

    Diffusion Monte Carlo (DMC) and path-integral Monte Carlo computations of the vibrational ground state and 10 K equilibrium state properties of the H7 (+)/D7 (+) cations are presented, using an ab initio full-dimensional potential energy surface. The DMC zero-point energies of dissociated fragments H5 (+)(D5 (+))+H2(D2) are also calculated and from these results and the electronic dissociation energy, dissociation energies, D0, of 752 ± 15 and 980 ± 14 cm(-1) are reported for H7 (+) and D7 (+), respectively. Due to the known error in the electronic dissociation energy of the potential surface, these quantities are underestimated by roughly 65 cm(-1). These values are rigorously determined for first time, and compared with previous theoretical estimates from electronic structure calculations using standard harmonic analysis, and available experimental measurements. Probability density distributions are also computed for the ground vibrational and 10 K state of H7 (+) and D7 (+). These are qualitatively described as a central H3 (+)/D3 (+) core surrounded by "solvent" H2/D2 molecules that nearly freely rotate.

  2. Dynamics of dissociative adsorption of hydrogen on Ni(100)

    International Nuclear Information System (INIS)

    Hamza, A.V.; Madix, R.J.

    1985-01-01

    Nearly monoenergetic beams of hydrogen and deuterium were used to determine dissociative sticking probabilities for H 2 and D 2 on Ni(100) at various energies. Variation of the surface temperature between 90 and 300 K had no effect on the dissociative sticking probability of H 2 at 3.6 and 5.8 kJ/mol incident beam energy, indicating a direct mechanism of dissociation. A four fold increase in the initial dissociative sticking probability for H 2 from 0.2 to 0.8 was observed by increasing the translational kinetic energy from 0.7 to 7.0 kJ/mol. The initial dissociative sticking probability for D 2 was slightly lower, increasing from 0.15 to 0.75 with increasing translational kinetic energy from 1.3 to 10.5 kJ/mol. The form of the increase with kinetic energy was explained by tunnelling through a low activation barrier, accounting as well for the high dissociation probability at low kinetic energies. The dissociative sticking probability decreased with hydrogen or deuterium adatom coverage at all energies. The decline in sticking probability with hydrogen coverage was fit to a s(theta) = s 0 (1 - a theta)/sup n/ functional form. From this relationship it was deduced that hydrogen adatoms block only single sites and that four vacant sites are needed for dissociation. The dissociative sticking probability for H 2 declined precipitously from 0.77 to 0.16 with oxygen adatom coverage from 0 to 5% of a monolayer at a translational energy of 9.6 kJ.mol. 36 references, 8 figures

  3. Dissociation of acetaldehyde in intense laser field: Coulomb explosion or field-assisted dissociation?

    Science.gov (United States)

    Elshakre, Mohamed E.; Gao, Lirong; Tang, Xiaoping; Wang, Sufan; Shu, Yafei; Kong, Fanao

    2003-09-01

    Dissociation of acetaldehyde in moderate strong laser field of 1013-1014W/cm2 was investigated. Singly charged parent ion CH3CHO+ and fragmental ions CH3+, CHO+, C2H4+, O+, CH2CHO+, and H+ were produced by 800 nm laser of 100 fs pulse duration and recorded by time-of-flight mass spectrometer. The CH3+ fragment further dissociated to CH2+, CH+, and C+ ions at higher intensity. Ab initio calculated results show that the singly-, doubly-, and triply charged parent ions are stable. So, the dissociation mechanism was not due to Coulomb explosion of multicharged ion. A field-assisted dissociation (FAD) theory, which assumes that only one bond undergoes dissociation while the rest of the molecular geometry stays unchanged, was employed to treat the dissociation dynamics. Accordingly, the dressed potential energy surfaces of the ground state for the parent and the fragment ions were calculated. Corresponding quasiclassical trajectory calculations show that the bond ruptures take place in the order of C-C, C-O, and C-H, agreeing with the observation. The observed angular dependence and charge distribution of the product ions can also be interpreted by the FAD theory.

  4. Dissociative Excitation of Thymine by Electron Impact

    Science.gov (United States)

    McConkey, William; Tiessen, Collin; Hein, Jeffrey; Trocchi, Joshuah; Kedzierski, Wladek

    2014-05-01

    A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of thymine (C5H6N2O2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. A special stainless steel oven is used to vaporize the thymine and form it into a beam where it is intersected by a magnetically collimated electron beam, typical current 50 μA. The main features in the spectrum are the H Lyman series lines. The probability of extracting excited C or N atoms from the ring is shown to be very small. In addition to spectral data, excitation probability curves as a function of electron energy will be presented for the main emission features. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.

  5. Atomic excitation and molecular dissociation by low energy electron collisions

    International Nuclear Information System (INIS)

    Weyland, Marvin

    2016-01-01

    In this work, momentum imaging experiments have been conducted for the electron impact excitation of metastable states in noble gases and for dissociative electron attachment (DEA) in polyatomic molecules. For the electron impact excitation study a new experimental technique has been developed which is able to measure the scattering angle distribution of the electrons by detection of the momentum transfer to the atoms. Momentum transfer images have been recorded for helium and neon at fixed electron impact energy close to the excitation threshold and good agreement with current R-matrix theory calculations was found. A new momentum imaging apparatus for negative ions has been built for the purpose of studying DEA in biologically relevant molecules. During this work, DEA was investigated in the molecules ammonia, water, formic acid, furan, pyridine and in two chlorofluorocarbons. Furthermore, the change of DEA resonance energies when molecules form clusters compared to monomers was investigated in ammonia and formic acid. The experimental results of most studied molecules could be compared to recent theoretical calculations and they support further development in the theoretical description of DEA. The new apparatus built in this work also delivered a superior momentum resolution compared to existing setups. This allows the momentum imaging of heavier fragments and fragments with lower kinetic energy.

  6. Atomic excitation and molecular dissociation by low energy electron collisions

    Energy Technology Data Exchange (ETDEWEB)

    Weyland, Marvin

    2016-11-16

    In this work, momentum imaging experiments have been conducted for the electron impact excitation of metastable states in noble gases and for dissociative electron attachment (DEA) in polyatomic molecules. For the electron impact excitation study a new experimental technique has been developed which is able to measure the scattering angle distribution of the electrons by detection of the momentum transfer to the atoms. Momentum transfer images have been recorded for helium and neon at fixed electron impact energy close to the excitation threshold and good agreement with current R-matrix theory calculations was found. A new momentum imaging apparatus for negative ions has been built for the purpose of studying DEA in biologically relevant molecules. During this work, DEA was investigated in the molecules ammonia, water, formic acid, furan, pyridine and in two chlorofluorocarbons. Furthermore, the change of DEA resonance energies when molecules form clusters compared to monomers was investigated in ammonia and formic acid. The experimental results of most studied molecules could be compared to recent theoretical calculations and they support further development in the theoretical description of DEA. The new apparatus built in this work also delivered a superior momentum resolution compared to existing setups. This allows the momentum imaging of heavier fragments and fragments with lower kinetic energy.

  7. Role of dispersion corrected hybrid GGA class in accurately calculating the bond dissociation energy of carbon halogen bond: A benchmark study

    Science.gov (United States)

    Kosar, Naveen; Mahmood, Tariq; Ayub, Khurshid

    2017-12-01

    Benchmark study has been carried out to find a cost effective and accurate method for bond dissociation energy (BDE) of carbon halogen (Csbnd X) bond. BDE of C-X bond plays a vital role in chemical reactions, particularly for kinetic barrier and thermochemistry etc. The compounds (1-16, Fig. 1) with Csbnd X bond used for current benchmark study are important reactants in organic, inorganic and bioorganic chemistry. Experimental data of Csbnd X bond dissociation energy is compared with theoretical results. The statistical analysis tools such as root mean square deviation (RMSD), standard deviation (SD), Pearson's correlation (R) and mean absolute error (MAE) are used for comparison. Overall, thirty-one density functionals from eight different classes of density functional theory (DFT) along with Pople and Dunning basis sets are evaluated. Among different classes of DFT, the dispersion corrected range separated hybrid GGA class along with 6-31G(d), 6-311G(d), aug-cc-pVDZ and aug-cc-pVTZ basis sets performed best for bond dissociation energy calculation of C-X bond. ωB97XD show the best performance with less deviations (RMSD, SD), mean absolute error (MAE) and a significant Pearson's correlation (R) when compared to experimental data. ωB97XD along with Pople basis set 6-311g(d) has RMSD, SD, R and MAE of 3.14 kcal mol-1, 3.05 kcal mol-1, 0.97 and -1.07 kcal mol-1, respectively.

  8. Measurements of the Coulomb dissociation cross section of 156 MeV 6Li projectiles at extremely low relative fragment energies of astrophysical interest

    International Nuclear Information System (INIS)

    Kiener, J.; Gils, H.J.; Rebel, H.; Zagromski, S.; Gsottschneider, G.; Heide, N.; Jelitto, H.; Wentz, J.; Baur, G.

    1991-04-01

    Coulomb dissociation of light nuclear projectiles in the electric field of heavy target nuclei has been experimentally investigated as an alternative access to radiative capture cross sections at low relative energies of the fragments, which are of astrophysical interest. As a pilot experiment the breakup of 156 MeV 6 Li-projectiles at 208 Pb with small emission angles of the a particle and deuteron fragments has been studied. Both fragments were coincidentally detected in the focal plane of a magnetic spectrograph at several reaction angles well below the grazing angle and with relative angles between the fragments of 0deg-2deg. The experimental cross sections have been analyzed on the basis of the Coulomb breakup theory. The results for the resonant breakup give evidence for the strong dominance of the Coulomb dissociation mechanism and the absence of nuclear distortions, while the cross section for the nonresonant breakup follow theoretical predictions of the astrophysical S-factor and extrapolations of corresponding radiative capture reaction cross section to very low c. m. energies of the a particle and deuterons. Various implications of the approach are discussed. (orig.) [de

  9. [Clinical Handling of Patients with Dissociative Disorders].

    Science.gov (United States)

    Okano, Kenichiro

    2015-01-01

    This paper discusses the way informed psychiatrists are expected to handle dissociative patients in clinical situations, with a specific focus on dissociative identity disorders and dissociative fugue. On the initial interview with dissociative patients, information on their history of trauma and any nascent dissociative symptoms in their childhood should be carefully obtained. Their level of stress in their current life should also be assessed in order to understand their symptomatology, as well as to predict their future clinical course. A psychoeducational approach is crucial; it might be helpful to give information on dissociative disorder to these patients as well as their family members in order to promote their adherence to treatment. Regarding the symptomatology of dissociative disorders, detailed symptoms and the general clinical course are presented. It was stressed that dissociative identity disorder and dissociative fugue, the most high-profile dissociative disorders, are essentially different in their etiology and clinical presentation. Dissociative disorders are often confused with and misdiagnosed as psychotic disorders, such as schizophrenia. Other conditions considered in terms of the differential diagnosis include borderline personality disorder as well as temporal lobe epilepsy. Lastly, the therapeutic approach to dissociative identity disorder is discussed. Each dissociative identity should be understood as potentially representing some traumatically stressful event in the past. The therapist should be careful not to excessively promote the creation or elaboration of any dissociative identities. Three stages are proposed in the individual psychotherapeutic process. In the initial stage, a secure environment and stabilization of symptoms should be sought. The second stage consists of aiding the "host" personality to make use of other more adaptive coping skills in their life. The third stage involves coaching as well as continuous awareness of

  10. Bound energy levels at the n=2 dissociation threshold in HD

    NARCIS (Netherlands)

    Pielage, T.G.P.; de Lange, A.; Brandi, F.; Ubachs, W.M.G.

    2002-01-01

    Level energies of g symmetry states lying just below the n = 2 dissociation threshold have been determined in a XUV + IR multi-step laser excitation experiment in HD, with an absolute accuracy of the excitation energy of 0.015 cm

  11. Data on ionization, excitation, dissociation and dissociative ionization of targets by helium ion bombardments, (1)

    International Nuclear Information System (INIS)

    Oda, Nobuo; Urakawa, Junji

    1984-03-01

    This report presents a compilation of the experimental data on cross sections for the ionization, excitation, dissociation and dissociative ionization processes of targets in helium ion impacts on atoms and molecules under a single collision condition. These measurements were carried out in the energy range from several keV to 3.5 MeV. A systematic survey has been made on the literatures from 1975 to the end of 1982. A list of references is also given, including relevant papers published before 1975. (author)

  12. Dissociation of Vertical Semiconductor Diatomic Artificial Molecules

    International Nuclear Information System (INIS)

    Pi, M.; Emperador, A.; Barranco, M.; Garcias, F.; Muraki, K.; Tarucha, S.; Austing, D. G.

    2001-01-01

    We investigate the dissociation of few-electron circular vertical semiconductor double quantum dot artificial molecules at 0T as a function of interdot distance. A slight mismatch introduced in the fabrication of the artificial molecules from nominally identical constituent quantum wells induces localization by offsetting the energy levels in the quantum dots by up to 2meV, and this plays a crucial role in the appearance of the addition energy spectra as a function of coupling strength particularly in the weak coupling limit

  13. [Characteristics of Bacillus cereus dissociants].

    Science.gov (United States)

    Doroshenko, E V; Loĭko, N G; Il'inskaia, O N; Kolpakov, A I; Gornova, I B; Klimanova, E V; El'-Registan, G I

    2001-01-01

    The autoregulation of the phenotypic (populational) variability of the Bacillus cereus strain 504 was studied. The isolated colonial morphotypes of this bacterium were found to differ in their growth characteristics and the synthesis of extracellular proteases. The phenotypic variabilities of vegetative proliferating cells and those germinated from endospores and cystlike refractory cells were different. Bacterial variants also differed in the production of the d1 and d2 factors (the autoinducers of dormancy and autolysis, respectively) and sensitivity to them. The possible role of these factors in the dissociation of microorganisms is discussed.

  14. Dissociation behavior of methane gas hydrate in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, C.; Yu-gang, Y.; Chang-ling, L. [Ministry of Land and Resources, Quindao (China). Qingdao Inst. of Marine Geology; Qing-guo, M. [Qingdao Univ. College of Chemical Engineering and Environment, Shandong, Qingdao (China)

    2008-07-01

    Gas hydrates are ice-like compounds that form by natural gas and water and are considered to be a new energy resource. In order to make good use of this resource, it is important to know the hydrate dissociation process. This paper discussed an investigation of methane hydrate dissociation through a simulation experiment. The paper discussed the gas hydrates dissociation experiment including the apparatus and experiment equipment, including methane gas supply; reaction cell; temperature controller; pressure maintainer; and gas flow meter. The paper also presented the method and material including iso-volumetric dissociation and normal pressure dissociation. Last, results and discussion of the results were presented. A comparison of five different particle sizes did not reveal any obvious effects that were related to the porous media, mostly likely because the particle size was too large. 15 refs., 2 tabs., 4 figs.

  15. Dissociative recombination of small molecular ions

    International Nuclear Information System (INIS)

    Mul, P.M.

    1981-01-01

    In this thesis an analysis is given of merged electron-ion beam experiment and work on dissociative recombination of molecular ions and electrons is described. Chapter II covers a brief introduction of the theory of dissociative recombination. In chapter III, a description is given of the merged electron-ion beam experiment and a method is described which allows the determination of the mean angle between the electron and ion trajectories in a merged electron-ion beam experiment. In chapter IV a paper on the three dominant atmospheric diatomic ions NO + , O 2 + and N 2 + is presented and in chapter V the dissociative recombination for N 2 H + and N 2 D + is discussed. In chapter VI two papers on the polyatomic ions of the carbon-containing molecular ions are presented, and in chapter VII a letter with some results of the work presented in more detail in the chapters IV, V and VI is presented. The magnitude and the energy dependence of the cross-section measured by the merged beam technique and by other techniques is compared and discussed. (Auth.)

  16. Metal cation dependence of interactions with amino acids: bond dissociation energies of Rb(+) and Cs(+) to the acidic amino acids and their amide derivatives.

    Science.gov (United States)

    Armentrout, P B; Yang, Bo; Rodgers, M T

    2014-04-24

    Metal cation-amino acid interactions are key components controlling the secondary structure and biological function of proteins, enzymes, and macromolecular complexes comprising these species. Determination of pairwise interactions of alkali metal cations with amino acids provides a thermodynamic vocabulary that begins to quantify these fundamental processes. In the present work, we expand a systematic study of such interactions by examining rubidium and cesium cations binding with the acidic amino acids (AA), aspartic acid (Asp) and glutamic acid (Glu), and their amide derivatives, asparagine (Asn) and glutamine (Gln). These eight complexes are formed using electrospray ionization and their bond dissociation energies (BDEs) are determined experimentally using threshold collision-induced dissociation with xenon in a guided ion beam tandem mass spectrometer. Analyses of the energy-dependent cross sections include consideration of unimolecular decay rates, internal energy of the reactant ions, and multiple ion-neutral collisions. Quantum chemical calculations are conducted at the B3LYP, MP2(full), and M06 levels of theory using def2-TZVPPD basis sets, with results showing reasonable agreement with experiment. At 0 and 298 K, most levels of theory predict that the ground-state conformers for M(+)(Asp) and M(+)(Asn) involve tridentate binding of the metal cation to the backbone carbonyl, amino, and side-chain carbonyl groups, although tridentate binding to the carboxylic acid group and side-chain carbonyl is competitive for M(+)(Asn). For the two longer side-chain amino acids, Glu and Gln, multiple structures are competitive. A comparison of these results to those for the smaller alkali cations, Na(+) and K(+), provides insight into the trends in binding energies associated with the molecular polarizability and dipole moment of the side chain. For all four metal cations, the BDEs are inversely correlated with the size of the metal cation and follow the order Asp < Glu

  17. CO dissociation on Ni: The effect of steps and of nickel carbonyl

    DEFF Research Database (Denmark)

    Engbæk, Jakob; Lytken, Ole; Nielsen, Jane Hvolbæk

    2008-01-01

    The dissociation of CO was investigated on a stepped Ni(141313) crystal. The experiments show that the monoatomic steps completely dominate the dissociation of CO on the nickel surface. The activation energy for dissociation of CO along the steps is measured at 500 K to be 150 kJ/mol in the press...... and in the Fischer-Tropsch synthesis....

  18. Electron Capture Dissociation of Weakly Bound Polypeptide Polycationic Complexes

    DEFF Research Database (Denmark)

    Haselmann, Kim F; Jørgensen, Thomas J D; Budnik, Bogdan A

    2002-01-01

    as well as specific complexes of modified glycopeptide antibiotics with their target peptide. The weak nature of bonding is substantiated by blackbody infrared dissociation, low-energy collisional excitation and force-field simulations. The results are consistent with a non-ergodic ECD cleavage mechanism.......We have previously reported that, in electron capture dissociation (ECD), rupture of strong intramolecular bonds in weakly bound supramolecular aggregates can proceed without dissociation of weak intermolecular bonds. This is now illustrated on a series of non-specific peptide-peptide dimers...

  19. Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems

    International Nuclear Information System (INIS)

    Meer, R. van; Gritsenko, O. V.; Baerends, E. J.

    2014-01-01

    Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ω α and oscillator strengths f α for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ω α (R) curves along the bond dissociation coordinate R for the molecules LiH, Li 2 , and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate

  20. Equilibrium dissociation pressures of lithium hydride and lithium deuteride

    International Nuclear Information System (INIS)

    Smith, H.M.; Webb, R.E.

    1977-12-01

    The equilibrium dissociation pressures of plateau composition lithium hydride and lithium deuteride have been measured from 450 to 750 0 C. These data were used to derive the relationship of dissociation pressure with temperature over this range and to calculate several thermodynamic properties of these materials. Thermodynamic properties determined included the enthalpy, entropy, and free energy of formation; the enthalpy and entropy of fusion; and the melting points

  1. Statistical Characterization of the Charge State and Residue Dependence of Low-Energy CID Peptide Dissociation Patterns

    International Nuclear Information System (INIS)

    Huang, Yingying; Triscari, Joseph M.; Tseng, George C.; Pasa-Tolic, Ljiljana; Lipton, Mary S.; Smith, Richard D.; Wysocki, Vicki H.

    2005-01-01

    Data mining was performed on 28 330 unique peptide tandem mass spectra for which sequences were assigned with high confidence. By dividing the spectra into different sets based on structural features and charge states of the corresponding peptides, chemical interactions involved in promoting specific cleavage patterns in gas-phase peptides were characterized. Pairwise fragmentation maps describing cleavages at all Xxx-Zzz residue combinations for b and y ions reveal that the difference in basicity between Arg and Lys results in different dissociation patterns for singly charged Arg- and Lys-ending tryptic peptides. While one dominant protonation form (proton localized) exists for Arg-ending peptides, a heterogeneous population of different protonated forms or more facile interconversion of protonated forms (proton partially mobile) exists for Lys-ending peptides. Cleavage C-terminal to acidic residues dominates spectra from peptides that have a localized proton and cleavage N-terminal to Pro dominates those that have a mobile or partially mobile proton. When Pro is absent from peptides that have a mobile or partially mobile proton, cleavage at each peptide bond becomes much more prominent. Whether the above patterns can be found in b ions, y ions, or both depends on the location of the proton holder(s). Enhanced cleavages C-terminal to branched aliphatic residues (Ile, Val, Leu) are observed in both b and y ions from peptides that have a mobile proton, as well as in y ions from peptides that have a partially mobile proton; enhanced cleavages N-terminal to these residues are observed in b ions from peptides that have a partially mobile proton. Statistical tools have been designed to visualize the fragmentation maps and measure the similarity between them. The pairwise cleavage patterns observed expand our knowledge of peptide gas-phase fragmentation behaviors and should be useful in algorithm development that employs improved models to predict fragment ion

  2. Dissociative Excitation of Adenine by Electron Impact

    Science.gov (United States)

    McConkey, J. William; Trocchi, Joshuah; Dech, Jeffery; Kedzierski, Wladek

    2017-04-01

    Dissociative excitation of adenine (C6H5NH2) into excited atomic fragments has been studied in the electron impact energy range from threshold to 300 eV. A crossed beam system coupled to a vacuum ultraviolet (VUV) monochromator is used to study emissions in the wavelength range from 110 to 200 nm. The beam of adenine vapor from a stainless steel oven is crossed at right angles by the electron beam and the resultant UV radiation is detected in a mutually orthogonal direction. The strongest feature in the spectrum is H Lyman- α. Financial support from NSERC and CFI, Canada, is gratefully acknowledged.

  3. Novel 2-Alkyl-1-Ethylpyridinium ionic liquids : synthesis, dissociation energies and volatility

    NARCIS (Netherlands)

    Vilas, M.; Alves da Rocha, M.A.; Fernandes, A.M.; Tojo, E.; Santos, L.M.N.B.F.

    2015-01-01

    This work presents the synthesis, volatility study and electrospray ionization mass spectrometry with energy-variable collision induced dissociation of the isolated [(cation)2(anion)]+ of a novel series of 2-alkyl-1-ethyl pyridinium based ionic liquids, [2CN-21C2Py][NTf2]. Compared to the

  4. Dissociation and the Development of Psychopathology.

    Science.gov (United States)

    Putnam, Frank W.; Trickett, Penelope K.

    This paper reviews the research on dissociation and the development of psychopathology in children and adolescents. Definitions and dimensions of dissociation are addressed, noting its range from normative daydreaming to the extremes found in individuals with multiple personality disorder. Memory dysfunctions, disturbances of identity, passive…

  5. From dissociation to trauma? Individual differences in dissociation as predictor of 'trauma' perception

    NARCIS (Netherlands)

    Rassin, Eric; van Rootselaar, Anne-Fleur

    2006-01-01

    In clinical literature, dissociative complaints are generally considered to be the result of traumatic experiences. However, it has been argued that dissociative complaints, in turn, may indulge over-reporting of traumatic experiences. Hence, correlations between dissociation and self-reported

  6. Diffractive dissociation and eikonalization in high energy pp and p bar p collisions

    International Nuclear Information System (INIS)

    Gotsman, E.; Levin, E.M.; Maor, U.

    1994-01-01

    We show that eikonal corrections imposed on diffraction dissociation processes calculated in the triple Regge limit produce a radical change in the energy dependence of the predicted cross section. The induced correction is shown to be in general agreement with the recent Fermilab Tevatron experimental data

  7. Coulomb dissociation of N-20,N-21

    NARCIS (Netherlands)

    Roeder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhaeuser, Roman; Goebel, Kathrin; Kalantar-Nayestanaki, Nasser; Najafi, Mohammad Ali; Rigollet, Catherine; Stoica, V.; Streicher, Branislav; Van de Walle, J.

    2016-01-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N-20,N-21 are reported. Relativistic N-20,N-21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a

  8. Is the dissociative adult suggestible? A test of the trauma and fantasy models of dissociation.

    Science.gov (United States)

    Kluemper, Nicole S; Dalenberg, Constance

    2014-01-01

    Psychologists have long assumed a connection between traumatic experience and psychological dissociation. This hypothesis is referred to as the trauma model of dissociation. In the past decade, a series of papers have been published that question this traditional causal link, proposing an alternative fantasy model of dissociation. In the present research, the relationship among dissociation, suggestibility, and fantasy proneness was examined. Suggestibility was measured through the Gudjonsson Scale of Interrogative Suggestibility (GSS) as well as an autobiographically based version of this measure based on the events of September 11, 2001. Consistent with prior research and with the trauma model, dissociation correlated positively with trauma severity (r = .32, p suggestibility measure. Although some participants did become quite emotional during the procedure, the risk/benefit ratio was perceived by almost all participants to be positive, with more reactive individuals evaluating the procedure more positively. The results consistently support the trauma model of dissociation and fail to support the fantasy model of dissociation.

  9. Study of SI engine fueled with methanol vapor and dissociation gas based on exhaust heat dissociating methanol

    International Nuclear Information System (INIS)

    Fu, Jianqin; Deng, Banglin; Liu, Jingping; Wang, Linjun; Xu, Zhengxin; Yang, Jing; Shu, Gequn

    2014-01-01

    Highlights: • The full load power decreases successively from gasoline engine, methanol vapor engine to dissociated methanol engine. • Both power and thermal efficiency of dissociated methanol engine can be improved by boosting pressure. • The conversion efficiency of recovered exhaust gas energy is largely influenced by the BMEP. • At the same BMEP, dissociated methanol engine has higher thermal efficiency than methanol vapor engine and gasoline engine. - Abstract: To improve the fuel efficiency of internal combustion (IC) engine and also achieve the goal of direct usage of methanol fuel on IC engine, an approach of exhaust heat dissociating methanol was investigated, which is a kind of method for IC engine exhaust heat recovery (EHR). A bottom cycle system is coupled with the IC engine exhaust system, which uses the exhaust heat to evaporate and dissociate methanol in its catalytic cracker. The methanol dissociation gas (including methanol vapor) is used as the fuel for IC engine. This approach was applied to both naturally aspirated (NA) engine and turbocharged engine, and the engine performance parameters were predicted by the software GT-power under various kinds of operating conditions. The improvement to IC engine performance and the conversion efficiency of recovered exhaust gas energy can be evaluated by comparing the performances of IC engine fueled with various kinds of fuels (or their compositions). Results show that, from gasoline engine, methanol vapor engine to dissociated methanol engine, the full load power decreases successively in the entire speed area due to the declining of volumetric efficiency, while it is contrary in the thermal efficiency at the same brake mean effective pressure (BMEP) level because of the improving of fuel heating value. With the increase of BMEP, the conversion efficiency of recovered exhaust gas energy is promoted. All those results indicate that the approach of exhaust heat dissociating methanol has large

  10. Dissociative Photoionization of the Elusive Vinoxy Radical.

    Science.gov (United States)

    Adams, Jonathan D; Scrape, Preston G; Lee, Shih-Huang; Butler, Laurie J

    2017-08-24

    These experiments report the dissociative photoionization of vinoxy radicals to m/z = 15 and 29. In a crossed laser-molecular beam scattering apparatus, we induce C-Cl bond fission in 2-chloroacetaldehyde by photoexcitation at 157 nm. Our velocity measurements, combined with conservation of angular momentum, show that 21% of the C-Cl photofission events form vinoxy radicals that are stable to subsequent dissociation to CH 3 + CO or H + ketene. Photoionization of these stable vinoxy radicals, identified by their velocities, which are momentum-matched with the higher-kinetic-energy Cl atom photofragments, shows that the vinoxy radicals dissociatively photoionize to give signal at m/z = 15 and 29. We calibrated the partial photoionization cross section of vinoxy to CH 3 + relative to the bandwidth-averaged photoionization cross section of the Cl atom at 13.68 eV to put the partial photoionization cross sections on an absolute scale. The resulting bandwidth-averaged partial cross sections are 0.63 and 1.3 Mb at 10.5 and 11.44 eV, respectively. These values are consistent with the upper limit to the cross section estimated from a study by Savee et al. on the O( 3 P) + propene bimolecular reaction. We note that the uncertainty in these values is primarily dependent on the signal attributed to C-Cl primary photofission in the m/z = 35 (Cl + ) time-of-flight data. While the value is a rough estimate, the bandwidth-averaged partial photoionization cross section of vinoxy to HCO + calculated from the signal at m/z = 29 at 11.53 eV is approximately half that of vinoxy to CH 3 + . We also present critical points on the potential energy surface of the vinoxy cation calculated at the G4//B3LYP/6-311++G(3df,2p) level of theory to support the observation of dissociative ionization of vinoxy to both CH 3 + and HCO + .

  11. Multiphoton ionization/dissociation of osmium tetroxide

    International Nuclear Information System (INIS)

    Ding, D.; Puretzky, A.A.; Compton, R.N.

    1993-01-01

    The mechanisms leading to laser multiphoton ionization and dissociation (MPI/MPD) of osmium tetroxide (OsO 4 ) have been investigated from measurements of the kinetic energies of product ions (Os + , Os 2+ , OsO + , O 2 + , O + ) and photoelectrons as a function of the laser wavelength. Neutral channels, intermediate to the dominant Os + ionization channel, such as OsO 4 →OsO 4-n +nO are examined using resonance-enhanced multiphoton ionization (REMPI) of the fast O atoms. Equipartition of the available photon energy among the fragments is observed. The wavelength dependence of the Os + ion signal suggests that one or more of the steps leading to Os + ions involve molecular ions and/or excited neutral atoms. The observed preponderance of very slow ( 2+ is shown to result primarily from REMPI of Os +

  12. Boltzmann rovibrational collisional coarse-grained model for internal energy excitation and dissociation in hypersonic flows.

    Science.gov (United States)

    Munafò, A; Panesi, M; Magin, T E

    2014-02-01

    A Boltzmann rovibrational collisional coarse-grained model is proposed to reduce a detailed kinetic mechanism database developed at NASA Ames Research Center for internal energy transfer and dissociation in N(2)-N interactions. The coarse-grained model is constructed by lumping the rovibrational energy levels of the N(2) molecule into energy bins. The population of the levels within each bin is assumed to follow a Boltzmann distribution at the local translational temperature. Excitation and dissociation rate coefficients for the energy bins are obtained by averaging the elementary rate coefficients. The energy bins are treated as separate species, thus allowing for non-Boltzmann distributions of their populations. The proposed coarse-grained model is applied to the study of nonequilibrium flows behind normal shock waves and within converging-diverging nozzles. In both cases, the flow is assumed inviscid and steady. Computational results are compared with those obtained by direct solution of the master equation for the rovibrational collisional model and a more conventional multitemperature model. It is found that the proposed coarse-grained model is able to accurately resolve the nonequilibrium dynamics of internal energy excitation and dissociation-recombination processes with only 20 energy bins. Furthermore, the proposed coarse-grained model provides a superior description of the nonequilibrium phenomena occurring in shock heated and nozzle flows when compared with the conventional multitemperature models.

  13. A quantitative relationship for the shock sensitivities of energetic compounds based on X-NO(2) (X=C, N, O) bond dissociation energy.

    Science.gov (United States)

    Li, Jinshan

    2010-08-15

    The ZPE-corrected X-NO(2) (X=C, N, O) bond dissociation energies (BDEs(ZPE)) of 11 energetic nitrocompounds of different types have been calculated employing density functional theory methods. Computed results show that using the 6-31G** basis set the UB3LYP calculated BDE(ZPE) is less than the UB3P86. For these typical energetic nitrocompounds the shock-initiated pressure (P(98)) is strongly related to the BDE(ZPE) indeed, and a polynomial correlation of ln(P(98)) with the BDE(ZPE) has been established successfully at different density functional theory levels, which provides a method to address the shock sensitivity problem. Copyright 2010 Elsevier B.V. All rights reserved.

  14. Low-energy cross sections of the BBN reaction d({alpha},{gamma}){sup 6}Li by Coulomb dissociation of {sup 6}Li

    Energy Technology Data Exchange (ETDEWEB)

    Heil, Michael; Suemmerer, Klaus [GSI Darmstadt (Germany); Hammache, Fairouz [IPN Orsay (France); Galaviz, Daniel [TU Darmstadt (Germany); Typel, Stefan [GANIL Caen (France)

    2008-07-01

    The primordial abundances of D, ({sup 3}He), {sup 4}He, and {sup 7}Li can be used to infer the baryon density of the Universe based on the framework of Big-Bang Nucleosynthesis (BBN). By precision measurements of the cosmic microwave background (CMB) an independent method became available recently. This lead to a renewed interest for BBN. Together with the recent observation of {sup 6}Li in old stars and the problems to reconcile calculated primordial {sup 7}Li abundances with those predicted on the basis of CMB results, the production of both, {sup 6}Li and {sup 7}Li in BBN has been reinvestigated. One important ingredient is the low-energy S-factor of the d-alpha radiative-capture reaction. Up to now, the only available experimental result by Kiener et al. (1991) introduced an uncertainty of about a factor of 20 in the {sup 6}Li yield. We have therefore reinvestigated the d-alpha reaction with the help of Coulomb dissociation (CD) of {sup 6}Li at 150 MeV/nucleon at GSI. CD is the only practical way to study the low-energy S-factor (which involves l=2 multipolarity) due to the large number of E2 photons contained in the equivalent-photon flux. Preliminary results indicate a drop of the S-factor as predicted by theory, contrary to the constant low-energy S-factor resulting from the previous study.

  15. Dissociation and Memory Fragmentation in Posttraumatic Stress Disorder: An Evaluation of the Dissociative Encoding Hypothesis

    Science.gov (United States)

    Bedard-Gilligan, Michele; Zoellner, Lori A.

    2012-01-01

    Several prominent theories of posttraumatic stress disorder (PTSD) posit that peritraumatic dissociation results in insufficient encoding of the trauma memory and that persistent dissociation prevents memory elaboration, resulting in memory fragmentation and PTSD. In this review, we summarize the empirical literature on peritraumatic and trait dissociation and trauma narrative fragmentation as measured by meta-memory and rater/objective coding. Across 16 studies to date, the association between dissociation and fragmentation was most prominent when examining peritraumatic dissociation and patient's own ratings of memory fragmentation. This relationship did not hold when examining trait dissociation or rater-coded or computer-generated measures of fragmentation. Thus, initial evidence points more toward a strong self-reported association between constructs that is not supported on more objective fragmentation coding. Measurement overlap, construct ambiguity, and exclusion of potential confounds may underlie lack of a strong association between dissociation and objective-rated fragmentation. PMID:22348400

  16. Dissociation of the Phenylarsane Molecular Ion: A Theoretical Study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Young; Choe, Joong Chul [Dongguk University, Seoul (Korea, Republic of)

    2010-09-15

    The potential energy surfaces (PESs) for the primary and secondary dissociations of the phenylarsane molecular ion (1a) were determined from the quantum chemical calculations using the G3(MP2)//B3LYP method. Several pathways for the loss of H· were determined and occurred though rearrangements as well as through direct bond cleavages. The kinetic analysis based on the PES for the primary dissociation showed that the loss of H{sub 2} was more favored than the loss of H·, but the H· loss competed with the H{sub 2} loss at high energies. The bicyclic isomer, 7-arsa-norcaradiene radical cation, was formed through the 1,2 shift of an α-H of 1a and played an important role as an intermediate for the further rearrangements in the loss of H· and the losses of As· and AsH. The reaction pathways for the formation of the major products in the secondary dissociations of [M-H]{sup +} and [M-H{sub 2}]{sup +·} were examined. The theoretical prediction explained the previous experimental results for the dissociation at high energies but not the dissociation at low energies.

  17. I. Dissociation free energies of drug-receptor systems via non-equilibrium alchemical simulations: a theoretical framework.

    Science.gov (United States)

    Procacci, Piero

    2016-06-01

    In this contribution I critically revise the alchemical reversible approach in the context of the statistical mechanics theory of non-covalent bonding in drug-receptor systems. I show that most of the pitfalls and entanglements for the binding free energy evaluation in computer simulations are rooted in the equilibrium assumption that is implicit in the reversible method. These critical issues can be resolved by using a non-equilibrium variant of the alchemical method in molecular dynamics simulations, relying on the production of many independent trajectories with a continuous dynamical evolution of an externally driven alchemical coordinate, completing the decoupling of the ligand in a matter of a few tens of picoseconds rather than nanoseconds. The absolute binding free energy can be recovered from the annihilation work distributions by applying an unbiased unidirectional free energy estimate, on the assumption that any observed work distribution is given by a mixture of normal distributions, whose components are identical in either direction of the non-equilibrium process, with weights regulated by the Crooks theorem. I finally show that the inherent reliability and accuracy of the unidirectional estimate of the decoupling free energies, based on the production of a few hundreds of non-equilibrium independent sub-nanosecond unrestrained alchemical annihilation processes, is a direct consequence of the funnel-like shape of the free energy surface in molecular recognition. An application of the technique to a real drug-receptor system is presented in the companion paper.

  18. Electron-impact dissociation of molecular hydrogen into neutral fragments

    Science.gov (United States)

    Scarlett, Liam H.; Tapley, Jonathan K.; Fursa, Dmitry V.; Zammit, Mark C.; Savage, Jeremy S.; Bray, Igor

    2018-02-01

    We present convergent close-coupling calculations of electron-impact dissociation of the ground state of molecular hydrogen into neutral fragments over the range of impact energies from 6 to 300 eV. The calculations account for dissociative excitation, excitation radiative decay dissociation, and predissociation through all bound electronic triplet states, and singlet states up to the D' 1 Π u state. An estimate is given for the contribution from the remaining bound electronic singlet states. Our results are in agreement with the recommended data of Yoon et al. [J. Phys. Chem. Ref. Data 37, 913 (2008)] in the low (6-12 eV) and high (60-70 eV) energy regions, but somewhat lower at the intermediate energies.

  19. Dissociation of acetone radical cation (CH3COCH3(+*) --> CH3CO(+) + CH3(*)): an ab initio direct classical trajectory study of the energy dependence of the branching ratio.

    Science.gov (United States)

    Zhou, Jia; Schlegel, H Bernhard

    2008-12-18

    The nonstatistical dissociation of acetone radical cation has been studied by ab initio direct classical trajectory calculations at the MP2/6-31G(d) level of theory. A bond additivity correction has been used to improve the MP2 potential energy surface (BAC-MP2). The energy dependence of the branching ratio, dissociation kinetics, and translational energy distribution for the two types of methyl groups have been investigated using microcanonical ensembles and specific mode excitation. In each case, the dissociation favors the loss of the newly formed methyl group, in agreement with the experiments. For microcanonical ensembles, the branching ratios for methyl loss are calculated to be 1.43, 1.88, 1.70, and 1.50 for 1, 2, 10, and 18 kcal/mol of excess energy, respectively. The energy dependence of the branching ratio is seen more dramatically in the excitation of individual modes involving C-C-O bending. For modes 3 and 6, the branching ratio rises to 1.6 and 1.8-2.3 when 1 or 2 kcal/mol are added, respectively, but falls off when more energy is added. For mode 8, the branching ratio continues to rise monotonically from 1.5 to 2.76 when 1-8 kcal/mol of excess energy are added.

  20. Dissociation in Psychiatric Disorders: A Meta-Analysis of Studies Using the Dissociative Experiences Scale.

    Science.gov (United States)

    Lyssenko, Lisa; Schmahl, Christian; Bockhacker, Laura; Vonderlin, Ruben; Bohus, Martin; Kleindienst, Nikolaus

    2018-01-01

    Dissociation is a complex, ubiquitous construct in psychopathology. Symptoms of dissociation are present in a variety of mental disorders and have been connected to higher burden of illness and poorer treatment response, and not only in disorders with high levels of dissociation. This meta-analysis offers a systematic and evidence-based study of the prevalence and distribution of dissociation, as assessed by the Dissociative Experiences Scale, within different categories of mental disorders, and it updates an earlier meta-analysis. More than 1,900 original publications were screened, and 216 were included in the meta-analysis, comprising 15,219 individuals in 19 diagnostic categories. The largest mean dissociation scores were found in dissociative disorders (mean scores >35), followed by posttraumatic stress disorder, borderline personality disorder, and conversion disorder (mean scores >25). Somatic symptom disorder, substance-related and addictive disorders, feeding and eating disorders, schizophrenia, anxiety disorder, OCD, and most affective disorders also showed mean dissociation scores >15. Bipolar disorders yielded the lowest dissociation scores (mean score, 14.8). The findings underline the importance of careful psychopathological assessment of dissociative symptoms in the entire range of mental disorders.

  1. Electron ionization and dissociation of aliphatic amino acids

    Science.gov (United States)

    Papp, P.; Shchukin, P.; Kočíšek, J.; Matejčík, Š.

    2012-09-01

    We present experimental and theoretical study of electron ionization and dissociative ionization to the gas phase amino acids valine, leucine, and isoleucine. A crossed electron/molecular beams technique equipped with quadrupole mass analyzer has been applied to measure mass spectra and ion efficiency curves for formation of particular ions. From experimental data the ionization energies of the molecules and the appearance energies of the fragment ions were determined. Ab initio calculations (Density Functional Theory and G3MP2 methods) were performed in order to calculate the fragmentation paths and interpret the experimental data. The experimental ionization energies of parent molecules [P]+ 8.91 ± 0.05, 8.85 ± 0.05, and 8.79 ± 0.05 eV and G3MP2 ionization energies (adiabatic) of 8.89, 8.88, and 8.81 eV were determined for valine, leucine, and isoleucine, respectively, as well as the experimental and theoretical threshold energies for dissociative ionization channels. The comparison of experimental data with calculations resulted in identification of the ions as well as the neutral fragments formed in the dissociative reactions. Around 15 mass/charge ratio fragments were identified from the mass spectra by comparison of experimental appearance energies with calculated reaction enthalpies for particular dissociative reactions.

  2. Dissociation of NF3 in shock waves

    International Nuclear Information System (INIS)

    Breshears, W.D.; Bird, P.F.

    1978-01-01

    The thermal dissociation rate of NF 3 in mixtures of 5% and 10%NF 3 in Ar has been measured behind incident shock waves over the temperature range 1330-2000 K. Dissociation rates were determined from postshock density gradients measured by laser beam deflection. The second order rate coefficient determined for NF 3 -Ar collisions is k/sub d/=2.31 x 10 15 exp(-20500/T) cm 3 mole sec

  3. Fast kinetics of calcium dissociation from calsequestrin

    Directory of Open Access Journals (Sweden)

    MARIANELA BELTRÁN

    2006-01-01

    Full Text Available We measured the kinetics of calcium dissociation from calsequestrin in solution or forming part of isolated junctional sarcoplasmic reticulum membranes by mixing calsequestrin equilibrated with calcium with calcium-free solutions in a stopped-flow system. In parallel, we measured the kinetics of the intrinsic fluorescence changes that take place following calcium dissociation from calsequestrin. We found that at 25ºC calcium dissociation was 10-fold faster for calsequestrin attached to junctional membranes (k = 109 s-1 than in solution. These results imply that calcium dissociation from calsequestrin in vivo is not rate limiting during excitation-contraction coupling. In addition, we found that the intrinsic fluorescence decrease for calsequestrin in solution or forming part of junctional membranes was significantly slower than the rates of calcium dissociation. The kinetics of intrinsic fluorescence changes had two components for calsequestrin associated to junctional membranes and only one for calsequestrin in solution; the faster component was 8-fold faster (k = 54.1 s-1 than the slower component (k = 6.9 s-1, which had the same k value as for calsequestrin in solution. These combined results suggest that the presence of calsequestrin at high concentrations in a restricted space, such as when bound to the junctional membrane, accelerates calcium dissociation and the resulting structural changes, presumably as a result of cooperative molecular interactions.

  4. Measurements of the charge exchange and dissociation cross-sections of the H{sub 2}+ ion in a wide energy range; Mesures des sections efficaces d'echange de charge et de dissociation des ions H{sub 2}{sup +} dans une large gamme d'energie (25 - 250 keV)

    Energy Technology Data Exchange (ETDEWEB)

    Guidini, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    The dissociation, ionisation, and charge exchange cross-sections of molecular hydrogen ions H{sub 2}{sup +} passing through various gases, have been measured as a function of the energy of the ions. The energy range studied was from 25 to 250 keV. The reaction products, analysed by a magnetic field according to their e/m ratio, are collected on scintillation detectors. Two methods have made it possible to separate the various reactions leading to the formation of particles having the same e/m ratio. The first separates the particles according to their energy, the other selects those arriving simultaneously on two different detectors. The results show a large variation in the charge exchange cross-section with the energy of the H{sub 2}{sup +} ions. The variations in the dissociation and ionisation cross-sections are less pronounced. For a given energy, the values of the cross-sections increase with the atomic weight of the target particles. These measurements have been extended to the case of H{sub 2}{sup +} ions passing through a target of charged particles. Preliminary results show an increase in the cross-sections as compared to the preceding case. Finally the scattering of the reaction products has been studied; this scattering is due to the fact that the molecules formed during a reaction are in an unstable state and the nuclei or atoms diverge from each other. (author) [French] Les sections efficaces de dissociation, d'ionisation et d'echange de charge d'ions hydrogene moleculaires H{sub 2}{sup +} traversant differents gaz, ont ete mesurees en fonction de l'energie des ions. La gamme d'energie exploree est comprise entre 25 et 250 keV. Les produits de reactions, analyses suivant leur rapport e/m par un champ magnetique, sont recus sur des detecteurs a scintillations. Deux methodes ont permis de separer les diverses reactions conduisant a la formation de particules ayant meme rapport e/m. L'une classe les particules secondaires en energie, l'autre selectionne

  5. Axial spatial distribution focusing: improving MALDI-TOF/RTOF mass spectrometric performance for high-energy collision-induced dissociation of biomolecules.

    Science.gov (United States)

    Belgacem, O; Pittenauer, E; Openshaw, M E; Hart, P J; Bowdler, A; Allmaier, G

    2016-02-15

    For the last two decades, curved field reflectron technology has been used in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometers, assisting in the generation of post-source-decay (PSD) or collision-induced dissociation (CID) without decelerating precursor ions, producing true high-energy CID spectra. The result was the generation of product ion mass spectra with product ions typical of high-energy (10 keV and beyond) collision processes. The disadvantage of this approach was the lack of resolution in CID spectra resulting from the excess laser energy deposition used to generate those MS/MS spectra. The work presented in this study overcomes this limitation and includes comprehensive examples of high-energy and high-resolution CID MALDI-MS/MS spectra of biomolecules. The devices used in this study are TOF/RTOF instruments equipped with a high-vacuum MALDI ion source. High-resolution and high-energy CID spectra result from the use of axial spatial distribution focusing (ASDF) in combination with curved field reflectron technology. A CID spectrum of the P14 R1 peptide exhibits product ion resolution in excess of 10,000 (FWHM) but at the same time yields typical high-energy product ions such as w- and [y-2]-type ion series. High-energy CID spectra of lipids, exemplified by a glycerophospholipid and triglyceride, demonstrate C-C backbone fragmentation elucidating the presence of a hydroxyl group in addition to double-bond positioning. A complex high mannose carbohydrate (Man)8 (GlcNAc)2 was also studied at 20 keV collision energy and revealed further high-energy product ions with very high resolution, allowing unambiguous detection and characterization of cross-ring cleavage-related ions. This is the first comprehensive study using a MALDI-TOF/RTOF instrument equipped with a curved field reflectron and an ASDF device prior to the reflectron. © 2015 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley

  6. Spectroscopic constants and the potential energy curve of the iodine weakly bound 0+g state correlating with the I(2P1/2) + I(2P1/2) dissociation limit

    International Nuclear Information System (INIS)

    Akopyan, M E; Baturo, V V; Lukashov, S S; Poretsky, S A; Pravilov, A M

    2013-01-01

    The stepwise three-step three-colour aser excitation scheme and rotational as well as rovibrational energy transfer processes in the 0 + g state induced by collisions with He and Ar atoms are used for determination of rovibronic level energies of the weakly bound 0 + g state correlating with the I( 2 P 1/2 ) + I( 2 P 1/2 ) dissociation limit. Dunham coefficients of the state, Y i0 (i = 0–3), Y i1 (i = 0–3) and Y 02 for the v 0 g + = 0–16 and J 0 g + ≈ 14–135 ranges as well as the dissociation energy of the state, D e , and equilibrium I–I distance of the state, R e , are determined. The potential energy curve of the state constructed using these constants is also reported. (paper)

  7. The co-occurrence of PTSD and dissociation: differentiating severe PTSD from dissociative-PTSD.

    Science.gov (United States)

    Armour, Cherie; Karstoft, Karen-Inge; Richardson, J Don

    2014-08-01

    A dissociative-posttraumatic stress disorder (PTSD) subtype has been included in the DSM-5. However, it is not yet clear whether certain socio-demographic characteristics or psychological/clinical constructs such as comorbid psychopathology differentiate between severe PTSD and dissociative-PTSD. The current study investigated the existence of a dissociative-PTSD subtype and explored whether a number of trauma and clinical covariates could differentiate between severe PTSD alone and dissociative-PTSD. The current study utilized a sample of 432 treatment seeking Canadian military veterans. Participants were assessed with the Clinician Administered PTSD Scale (CAPS) and self-report measures of traumatic life events, depression, and anxiety. CAPS severity scores were created reflecting the sum of the frequency and intensity items from each of the 17 PTSD and 3 dissociation items. The CAPS severity scores were used as indicators in a latent profile analysis (LPA) to investigate the existence of a dissociative-PTSD subtype. Subsequently, several covariates were added to the model to explore differences between severe PTSD alone and dissociative-PTSD. The LPA identified five classes: one of which constituted a severe PTSD group (30.5 %), and one of which constituted a dissociative-PTSD group (13.7 %). None of the included, demographic, trauma, or clinical covariates were significantly predictive of membership in the dissociative-PTSD group compared to the severe PTSD group. In conclusion, a significant proportion of individuals report high levels of dissociation alongside their PTSD, which constitutes a dissociative-PTSD subtype. Further investigation is needed to identify which factors may increase or decrease the likelihood of membership in a dissociative-PTSD subtype group compared to a severe PTSD only group.

  8. Dissociative photo-multiple-ionisation of CO and CO2

    International Nuclear Information System (INIS)

    Bapat, B; Sharma, Vandana; Prajapati, I A; Subramanian, K P; Singh, R K; Lodha, G S

    2007-01-01

    In a photoelectron-photoion coincidence experiment on CO and CO 2 , we have observed the formation and fragmentation of singly to triply charged CO 2 and singly to quadruply charged CO at various energies. Doubly charged cations of both molecules are found to have unstable as well as stable states. Cations with higher charge are found to dissociate promptly. The energy dependence of the relative partial cross-sections in the energy range 125-310 eV are presented

  9. [Screening for major dissociative disorders with the FDS, the German version of the Dissociative Experience Scale].

    Science.gov (United States)

    Rodewald, Frauke; Gast, Ursula; Emrich, Hinderk M

    2006-06-01

    The prevalence of major dissociative disorders (dissociative identity disorder, DID and similar forms of dissociative disorder not otherwise specified, DDNOS) in clinical samples is about 5 %. Despite their frequency, major dissociative disorders are often overseen for a long time. Screening-scales have proved to be effective to support clinical diagnosis. The aim of this study was to test, whether the Fragebogen für dissoziative Symptome (FDS), the German version of the Dissociative Experiences Scale (DES), differentiates between patients with dissociative disorders, non-dissociative disorders and non-clinical controls. Additionally, an optimal FDS-cutoff for a more detailed differential-diagnostic evaluation of the dissociative symptomatology should be identified. 150 participants with DID (group DID: n = 44), DDNOS (DDNOS: n = 22), posttraumatic disorders (TRAUMA: n = 20), other non-dissociative disorders (non-TRAUMA: n = 34) and non-clinical controls (KG: n = 30) completed the FDS. In the five diagnostic groups, mean values were calculated and compared for the FDS, DES and FDS-20. Via receiver-operating-curves the cutoff-scores, which differentiated best between participants with and without major dissociative disorders, were identified. FDS, DES and FDS-20 differentiate significantly between patients with and without major dissociative disorders. For all scales, there were significant differences between the diagnostic groups, with mean-scores decreasing continuously from the groups DID to DDNOS and TRAUMA. Between the groups non-TRAUMA and KG tendencies were found in the predicted direction. The optimal cutoff-scores to differentiate between participants with and without major dissociative disorders were 13 (FDS/FDS-20) and 15 (DES). Using these cutoff-scores, at least 90 % of the patients with major dissociative disorders could be identified correctly (sensitivity). The specifity of the scales was 0.89 to 0.90. Screening for major dissociative disorders

  10. Modeling dissociation behaviour of methane hydrate in porous soil media

    Energy Technology Data Exchange (ETDEWEB)

    Jayasinghe, A.G.; Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

    2008-07-01

    Gas hydrates, or clathrates, exist in the form of crystalline solid structures of hydrogen bonded water molecules where the lattice cages are occupied by guest gas molecules. Methane gas hydrates are the most common. As such, hydrate bearing sediments are considered to be a potential future energy resource. Gas hydrates also function as a source or sink for atmospheric methane, which may influence global warming. The authors emphasized that an understanding of the behaviour of soils containing gas hydrates is necessary in order to develop ways of recovering the vast gas resources that exist in the form of hydrates, particularly since hydrates are also suspected to be a potential factor in the initiation and propagation of submarine slope failures. Gas hydrate dissociation occurs when water and gas are released, resulting in an increase in pore fluid pressure, thereby causing significant reductions in effective stress leading to sediment failure. Dissociation may occur as a result of pressure reductions or increases in temperature. This study focused on the strength and deformation behaviour of hydrate bearing soils associated with temperature induced dissociation. Modeling the dissociation behavior of hydrates in porous soil media involves an understanding of the geomechanics of hydrate dissociation. This paper addressed the issue of coupling the hydrate dissociation problem with the soil deformation problem. A mathematical framework was constructed in which the thermally stimulated hydrate dissociation process in porous soil media under undrained conditions was considered with conduction heat transfer. It was concluded that a knowledge of geomechanical response of hydrate bearing sediments will enable better estimates of benefits and risks associated with the recovery process, thereby ensuring safe and economical exploration. 20 refs., 1 fig., 1 appendix.

  11. Dynamics of dissociation versus ionization in strong laser fields

    International Nuclear Information System (INIS)

    DiMauro, L.F.; Yang, B.

    1993-01-01

    In this paper, experimental results are presented which clearly demonstrate the effectiveness that an external field has in altering the dissociation dynamics. The experiment examines the strong-field dissociation dynamics of molecular hydrogen ions and its deuterated isotopes. These studies involve multiphoton excitation in the intensity regime of 10 11-14 W/cm 2 with the fundamental and second harmonic of a ND:YAG or ND:YLF laser system. Measurements include energy resolved electron and mass spectroscopy which provide useful probes in elucidating the interaction dynamics predicted by existing models. The example this in this paper, examines the strong-field dissociation of H 2 + , HD + , and D 2 + at green (0.5 μm) and (1μm) frequencies. The diatomic ions are formed via multiphonon ionization of the neutral precursor which is physically separable from the dissociation process. This study provides the first observation of the dynamics associated with the above threshold dissociation (ATD) process and analogies will be made with the more familiar above threshold ionization (ATI) phenomenon

  12. Reaction paths of phosphine dissociation on silicon (001)

    Energy Technology Data Exchange (ETDEWEB)

    Warschkow, O.; McKenzie, D. R. [Centre for Quantum Computation and Communication Technology, School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia); Curson, N. J. [Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales, Sydney, NSW 2052 (Australia); London Centre for Nanotechnology and Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Schofield, S. R. [Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales, Sydney, NSW 2052 (Australia); London Centre for Nanotechnology and Department of Physics and Astronomy, University College, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Marks, N. A. [Centre for Quantum Computation and Communication Technology, School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia); Discipline of Physics & Astronomy, Curtin University, GPO Box U1987, Perth, WA (Australia); Wilson, H. F. [Centre for Quantum Computation and Communication Technology, School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia); CSIRO Virtual Nanoscience Laboratory, Parkville, VIC 3052 (Australia); School of Applied Sciences, RMIT University, Melbourne, VIC 3000 (Australia); Radny, M. W.; Smith, P. V. [School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308 (Australia); Reusch, T. C. G.; Simmons, M. Y. [Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales, Sydney, NSW 2052 (Australia)

    2016-01-07

    Using density functional theory and guided by extensive scanning tunneling microscopy (STM) image data, we formulate a detailed mechanism for the dissociation of phosphine (PH{sub 3}) molecules on the Si(001) surface at room temperature. We distinguish between a main sequence of dissociation that involves PH{sub 2}+H, PH+2H, and P+3H as observable intermediates, and a secondary sequence that gives rise to PH+H, P+2H, and isolated phosphorus adatoms. The latter sequence arises because PH{sub 2} fragments are surprisingly mobile on Si(001) and can diffuse away from the third hydrogen atom that makes up the PH{sub 3} stoichiometry. Our calculated activation energies describe the competition between diffusion and dissociation pathways and hence provide a comprehensive model for the numerous adsorbate species observed in STM experiments.

  13. Reaction paths of phosphine dissociation on silicon (001)

    International Nuclear Information System (INIS)

    Warschkow, O.; McKenzie, D. R.; Curson, N. J.; Schofield, S. R.; Marks, N. A.; Wilson, H. F.; Radny, M. W.; Smith, P. V.; Reusch, T. C. G.; Simmons, M. Y.

    2016-01-01

    Using density functional theory and guided by extensive scanning tunneling microscopy (STM) image data, we formulate a detailed mechanism for the dissociation of phosphine (PH 3 ) molecules on the Si(001) surface at room temperature. We distinguish between a main sequence of dissociation that involves PH 2 +H, PH+2H, and P+3H as observable intermediates, and a secondary sequence that gives rise to PH+H, P+2H, and isolated phosphorus adatoms. The latter sequence arises because PH 2 fragments are surprisingly mobile on Si(001) and can diffuse away from the third hydrogen atom that makes up the PH 3 stoichiometry. Our calculated activation energies describe the competition between diffusion and dissociation pathways and hence provide a comprehensive model for the numerous adsorbate species observed in STM experiments

  14. Reconsidering the autohypnotic model of the dissociative disorders.

    Science.gov (United States)

    Dell, Paul F

    2018-03-22

    The dissociative disorders field and the hypnosis field currently reject the autohypnotic model of the dissociative disorders, largely because many correlational studies have shown hypnotizability and dissociation to be minimally related (r = .12). Curiously, it is also widely accepted that dissociative patients are highly hypnotizable. If dissociative patients are highly hypnotizable because only highly hypnotizable individuals can develop a dissociative disorder - as the author proposes - then the methodology of correlational studies of hypnotizability and dissociation in random clinical and community samples would necessarily be constitutively unable to detect, and statistically unable to reflect, that fact. That is, the autohypnotic, dissociative distancing of that small subset of highly hypnotizable individuals who repeatedly encountered intolerable circumstances is statistically lost among the data of (1) the highly hypnotizable subjects who do not dissociate and (2) subjects (of all levels of hypnotizability) who manifest other kinds of dissociation. The author proposes that, when highly hypnotizable individuals repeatedly engage in autohypnotic distancing from intolerable circumstances, they develop an overlearned, highly-motivated, automatized pattern of dissociative self-protection (i.e., a dissociative disorder). The author urges that theorists of hypnosis and the dissociative disorders explicitly include in their theories (a) the trait of high hypnotizability, (b) the phenomena of autohypnosis, and (c) the manifestations of systematized, autohypnotic pathology. Said differently, the author is suggesting that autohypnosis and autohypnotic pathology are unacknowledged nodes in the nomothetic networks of both hypnosis and dissociation.

  15. The co-occurrence of PTSD and dissociation: differentiating severe PTSD from dissociative-PTSD

    DEFF Research Database (Denmark)

    Armour, C.; Karstoft, K. I.; Richardson, J. D.

    2014-01-01

    A dissociative-posttraumatic stress disorder (PTSD) subtype has been included in the DSM-5. However, it is not yet clear whether certain socio-demographic characteristics or psychological/clinical constructs such as comorbid psychopathology differentiate between severe PTSD and dissociative-PTSD....... The current study investigated the existence of a dissociative-PTSD subtype and explored whether a number of trauma and clinical covariates could differentiate between severe PTSD alone and dissociative-PTSD. The current study utilized a sample of 432 treatment seeking Canadian military veterans. Participants...... were assessed with the Clinician Administered PTSD Scale (CAPS) and self-report measures of traumatic life events, depression, and anxiety. CAPS severity scores were created reflecting the sum of the frequency and intensity items from each of the 17 PTSD and 3 dissociation items. The CAPS severity...

  16. Production of dissociated hydrogen gas by electro-magnetically driven shock

    International Nuclear Information System (INIS)

    Kondo, Kotaro; Moriyama, Takao; Hasegawa, Jun; Horioka, Kazuhiko; Oguri, Yoshiyuki

    2013-01-01

    Evaluation of ion stopping power which has a dependence on target temperature and density is an essential issue for heavy-ion-driven high energy density experiment. We focus on experimentally unknown dissociated hydrogen atoms as target for stopping power measurement. The precise measurement of shock wave velocity is required because the dissociated gas is produced by electro-magnetically driven shock. For beam-dissociated hydrogen gas interaction experiment, shock velocity measurement using laser refraction is proposed. (author)

  17. High-order above-threshold dissociation of molecules

    Science.gov (United States)

    Lu, Peifen; Wang, Junping; Li, Hui; Lin, Kang; Gong, Xiaochun; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Ma, Junyang; Li, Hanxiao; Zeng, Heping; He, Feng; Wu, Jian

    2018-03-01

    Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics.

  18. Coulomb dissociation of N 20,21

    OpenAIRE

    Röder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos

    2016-01-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is...

  19. A storage ring study of dissociative excitation and recombination of D3+

    International Nuclear Information System (INIS)

    Le Padellec, A.; Larson, Aa.; Semaniak, J.; Stroemholm, C.; Larsson, M.; Rosen, S.; Danared, H.; Peterson, J.R.

    1998-01-01

    Dissociative recombination and excitation of D 3 + have been studied in CRYRING, a heavy-ion storage ring at the Manne Siegbahn laboratory at Stockholm University. The measured cross section for dissociative recombination was used to deduce a 300 K rate constant of 2.7 x 10 -8 cm 3 s -1 . This is a factor of four smaller than the corresponding value for H 3 + measured earlier in CRYRING. Dissociative excitation into both the D and 2D channels (D + D or D 2 ) were studied. The 2D channel occurs at energies below threshold for the ion's dissociative states, which indicates that resonant enhanced dissociative excitation via autoionizing resonances takes place. No measurable effect could be observed for the dissociative recombination cross sections when an electric field of 30 V/cm was applied to the electron-ion interaction region. (orig.)

  20. Theory of the dissociation process, ch. 1

    International Nuclear Information System (INIS)

    Asselt, N.P.F.B. van

    1976-01-01

    The formalism of Moeller operators and channel Hamiltonians, originating from scattering theory, is used for the description of the dissociation process. The proper choice of the initial state wave function is discussed. A method is given which accounts for the symmetry requirements which appear in the case of a homonuclear molecule where identical particles are present

  1. Objective documentation of child abuse and dissociation in 12 murderers with dissociative identity disorder.

    Science.gov (United States)

    Lewis, D O; Yeager, C A; Swica, Y; Pincus, J H; Lewis, M

    1997-12-01

    The skepticism regarding the existence of dissociative identity disorder as well as the abuse that engenders it persists for lack of objective documentation. This is doubly so for the disorder in murderers because of issues of suspected malingering. This article presents objective verification of both dissociative symptoms and severe abuse during childhood in a series of adult murderers with dissociative identity disorder. This study consisted of a review of the clinical records of 11 men and one woman with DSM-IV-defined dissociative identity disorder who had committed murder. Data were gathered from medical, psychiatric, social service, school, military, and prison records and from records of interviews with subjects' family members and others. Handwriting samples were also examined. Data were analyzed qualitatively. Signs and symptoms of dissociative identity disorder in childhood and adulthood were corroborated independently and from several sources in all 12 cases; objective evidence of severe abuse was obtained in 11 cases. The subjects had amnesia for most of the abuse and underreported it. Marked changes in writing style and/or signatures were documented in 10 cases. This study establishes, once and for all, the linkage between early severe abuse and dissociative identity disorder. Further, the data demonstrate that the disorder can be distinguished from malingering and from other disorders. The study shows that it is possible, with great effort, to obtain objective evidence of both the symptoms of dissociative identity disorder and the abuse that engenders it.

  2. Psychometric properties of the Dissociative Experiences Scale.

    Science.gov (United States)

    Dubester, K A; Braun, B G

    1995-04-01

    The test-retest reliability of the Dissociative Experiences Scale (DES; Bernstein EM, Putnam FW [1986] Development, reliability, and validity of a dissociation scale. The Journal of Nervous and Mental Disease 174:727-735) in a clinical sample was found to be .93 for the total DES score and .95, .89, and .82 for the three subscale scores of amnesia, depersonalization-derealization, and absorption (dissociative identity disorder [DID], DSM-IV), respectively. Test-retest reliabilities within diagnostic groups of multiple personality disorder, dissociative disorder not otherwise specified, and a general other category of psychiatric diagnoses were obtained for total and subscale scores on the DES. These ranged from .78 to .96. Tests of mean scores across the two test sessions showed the total and subscale scores to be temporally stable. The DES was also found to be highly internally consistent: Cronbach's alphas of .96 and .97 were observed for the total DES scores taken at times 1 and 2, respectively. Construct validity of the DES was demonstrated by differentiation among the subscale scores in a repeated-measures analysis of variance (F[2,154] = 32.03, p < or = .001). Normality and general distribution issues were also addressed and provided a rationale for using the DES with parametric statistics. Reasons why the DES (as it was originally designed) is not appropriate as a dependent measure in outcome research are discussed, along with needed future research. Implications of the findings for the clinical usefulness of the DES as a diagnostic instrument are noted.

  3. Transport coefficients of a dissociating gas

    International Nuclear Information System (INIS)

    Lebed', I.V.

    1987-01-01

    The calculation of the transport coefficients of a dissociating gas involves fundamental difficulties which arise when the internal degrees of freedom of the molecules are taken strictly into account. In practical calculations extensive use is made of the approximation in the context of which the dependence of a diffusion velocity of the molecule on its internal state is totally neglected. In this case the expressions for the stress tensor and the diffusion velocities coincide with the corresponding expressions for a mixture of structureless particles; in the expression for the heat flux the diffusion transport of internal energy is taken only approximately into account. Here, analytic expressions for the diffusion velocities, heat flux and stress tensor are obtained without introducing simplifying assumptions. The calculation method is based on an approximate method of calculating the transport coefficients of a multicomponent mixture of structureless particles. The relations obtained are analyzed and compared with the existing results; their accuracy is estimated. A closed system of equations of gas dynamics is presented for a number of cases of practical importance

  4. Photofragment translational spectroscopy of three body dissociations and free radicals

    Energy Technology Data Exchange (ETDEWEB)

    North, Simon William [Univ. of California, Berkeley, CA (United States)

    1995-04-01

    This dissertation describes several three-body dissociations and the photodissociation of methyl radicals studied using photofragment translational spectroscopy. The first chapter provides an introduction to three body dissociation, examines current experimental methodology, and includes a discussion on the treatment of photofragment translational spectroscopy data arising from three-body fragmentation. The ultraviolet photodissociation of azomethane into two methyl radicals and nitrogen is discussed in chapter 2. Chapter 3 describes the photodissociation of acetone at 248 nm and 193 nm. At 248 nm the translational energy release from the initial C-C bond cleavage matches the exit barrier height and a comparison with results at 266 nm suggests that T> is invariant to the available energy. A fraction of the nascent CH3CO radicals spontaneously dissociate following rotational averaging. The T> for the second C-C bond cleavage also matches the exit barrier height. At 193 nm the experimental data can be successfully fit assuming that the dynamics are analogous to those at 248 nm. A simplified model of energy partitioning which adequately describes the experimental results is discussed. Experiments on acetyl halides provide additional evidence to support the proposed acetone dissociation mechanism. A value of 17.0±1.0 kcal/mole for the barrier height, CH3CO decomposition has been determined. The photodissociation of methyl radical at 193 nm and 212.8 nm is discussed in the chapter 5. The formation of CH2(1Al) and H (2S) was the only single photon dissociation pathway observed at both wavelengths.

  5. Direct glycan structure determination of intact N-linked glycopeptides by low-energy collision-induced dissociation tandem mass spectrometry and predicted spectral library searching.

    Science.gov (United States)

    Pai, Pei-Jing; Hu, Yingwei; Lam, Henry

    2016-08-31

    Intact glycopeptide MS analysis to reveal site-specific protein glycosylation is an important frontier of proteomics. However, computational tools for analyzing MS/MS spectra of intact glycopeptides are still limited and not well-integrated into existing workflows. In this work, a new computational tool which combines the spectral library building/searching tool, SpectraST (Lam et al. Nat. Methods2008, 5, 873-875), and the glycopeptide fragmentation prediction tool, MassAnalyzer (Zhang et al. Anal. Chem.2010, 82, 10194-10202) for intact glycopeptide analysis has been developed. Specifically, this tool enables the determination of the glycan structure directly from low-energy collision-induced dissociation (CID) spectra of intact glycopeptides. Given a list of possible glycopeptide sequences as input, a sample-specific spectral library of MassAnalyzer-predicted spectra is built using SpectraST. Glycan identification from CID spectra is achieved by spectral library searching against this library, in which both m/z and intensity information of the possible fragmentation ions are taken into consideration for improved accuracy. We validated our method using a standard glycoprotein, human transferrin, and evaluated its potential to be used in site-specific glycosylation profiling of glycoprotein datasets from LC-MS/MS. In addition, we further applied our method to reveal, for the first time, the site-specific N-glycosylation profile of recombinant human acetylcholinesterase expressed in HEK293 cells. For maximum usability, SpectraST is developed as part of the Trans-Proteomic Pipeline (TPP), a freely available and open-source software suite for MS data analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Development of a collision induced dissociation ion cyclotron resonance spectrometer

    International Nuclear Information System (INIS)

    Fan, Y.N.

    1982-01-01

    A transient analysis ion cyclotron resonance spectrometer is developed to investigate the phenomena of collision induced dissociation. The Fourier transform method and the modified maximum entropy spectral analysis or covariance least square method are implemented in measuring the mass spectrum of the ion ensemble. The Fourier transform method can be used in quantitative analysis while the maximum entropy method as developed here is useful for qualitative analysis only. The cyclotron resonance frequency, relaxation time constant, and the relative ion population are observable from the Fourier transform spectrum. These parameters are very important in investigating collision induced dissociation process and other topics in gas phase chemistry. The ion cyclotron resonance spectrometer is not only developed to study fragments and their abundance from a parent ion, but also to determine the threshold energy and reaction cross section in the collision induced dissociation process. When hard sphere model is used in the ion-molecule collision, the radius of acetone ion measured from the reactive cross section is 2.2 angstrom which is very close to the physical dimension of acetone. The threshold energy for acetone ion in collision induced dissociation process is 1.8 eV which is similar to the result obtained by the angle-resolved mass spectrometer

  7. Visuomotor Dissociation in Cerebral Scaling of Size

    NARCIS (Netherlands)

    Potgieser, Adriaan R. E.; de Jong, Bauke M.

    2016-01-01

    Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in

  8. The elastic properties, generalized stacking fault energy and dissociated dislocations in MgB2 under different pressure

    KAUST Repository

    Feng, Huifang

    2013-05-31

    The 〈112̄0〉 perfect dislocation in MgB2 is suggested to dissociate into two partial dislocations in an energy favorable way 〈112̄0〉 → 1/2 〈112̄0〉 + SF + 1/2 〈112̄0〉. This dissociation style is a correction of the previous dissociation 〈1000〉 → 1/3 〈11̄00〉 SF + 1/3 〈 2100〉proposed by Zhu et al. to model the partial dislocations and stacking fault observed by transmission electron microscopy. The latter dissociation results in a maximal stacking fault energy rather than a minimal one according to the generalized stacking fault energy calculated from first-principles methods. Furthermore, the elastic constants and anisotropy of MgB2 under different pressure are investigated. The core structures and mobilities of the 〈112̄0〉 dissociated dislocations are studied within the modified Peierls-Nabarro (P-N) dislocation theory. The variational method is used to solve the modified P-N dislocation equation and the Peierls stress is also determined under different pressure. High pressure effects on elastic anisotropy, core structure and Peierls stress are also presented. © 2013 Springer Science+Business Media New York.

  9. The Parenting Experiences of Mothers with Dissociative Disorders.

    Science.gov (United States)

    Benjamin, Lynn R.; Benjamin, Robert; Rind, Bruce

    1998-01-01

    Presents a qualitative analysis of the experience of parenting of mothers with dissociative disorders. Using the mothers' words, describes how the five symptom areas of dissociation impeded their parenting efforts. Discusses the necessity of addressing parenting in the treatment of client-mothers with dissociative disorders. (Author/MKA)

  10. Collision-induced dissociation of aflatoxins.

    Science.gov (United States)

    Tóth, Katalin; Nagy, Lajos; Mándi, Attila; Kuki, Ákos; Mézes, Miklós; Zsuga, Miklós; Kéki, Sándor

    2013-02-28

    The aflatoxin mycotoxins are particularly hazardous to health when present in food. Therefore, from an analytical point of view, knowledge of their mass spectrometric properties is essential. The aim of the present study was to describe the collision-induced dissociation behavior of the four most common aflatoxins: B1, B2, G1 and G2. Protonated aflatoxins were produced using atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) combined with high-performance liquid chromatography (HPLC). For the tandem mass spectrometry (MS/MS) experiments nitrogen was used as the collision gas and the collision energies were varied in the range of 9-44 eV (in the laboratory frame). The major APCI-MS/MS fragmentations of protonated aflatoxins occurred at 30 eV collision energy. The main fragmentation channels were found to be the losses of a series of carbon monoxide molecules and loss of a methyl radical, leading to the formation of radical-type product ions. In addition, if the aflatoxin molecule contained an ether- or lactone-oxygen atom linked to a saturated carbon atom, loss of a water molecule was observed from the [M + H](+) ion, especially in the case of aflatoxins G1 and G2. A relatively small modification in the structure of aflatoxins dramatically altered the fragmentation pathways and this was particularly true for aflatoxins B1 and B2. Due to the presence of a C = C double bond connected to the ether group in aflatoxin B1 no elimination of water was observed but, instead, formation of radical-type product ions occurred. Fragmentation of protonated aflatoxin B1 yielded the most abundant radical-type cations. Copyright © 2013 John Wiley & Sons, Ltd.

  11. Energy distribution in selected fragment vibrations in dissociation processes in polyatomic molecules

    International Nuclear Information System (INIS)

    Band, Y.B.; Freed, K.F.

    1977-01-01

    The full quantum theory of dissociation processes in polyatomic molecules is converted to a form enabling the isolation of a selected fragment vibration. This form enables the easy evaluation of the probability distribution for energy partitioning between this vibration and all other degrees of freedom that results from the sudden Franck--Condon rearrangement process. The resultant Franck--Condon factors involve the square of the one-dimensional overlap integral between effective oscillator wavefunctions and the wavefunctions for the selected fragment vibration, a form that resembles the simple golden rule model for polyatomic dissociation and reaction processes. The full quantum theory can, therefore, be viewed as providing both a rigorous justification for certain generic aspects of the simple golden rule model as well as providing a number of important generalizations thereof. Some of these involve dealing with initial bound state vibrational excitation, explicit molecule, fragment and energy dependence of the effective oscillator, and the incorporation of all isotopic dependence. In certain limiting situations the full quantum theory yields simple, readily usable analytic expressions for the frequency and equilibrium position of the effective oscillator. Specific applications are presented for the direct photodissociation of HCN, DCN, and CO 2 where comparisons between the full theory and the simple golden rule are presented. We also discuss the generalizations of the previous theory to enable the incorporation of effects of distortion in the normal modes as a function of the reaction coordinate on the repulsive potential energy surface

  12. Photoionization and dissociative photoionization study of HFC-152a using synchrotron radiation

    International Nuclear Information System (INIS)

    Huang Chaoqun; Wei Lixia; Yang Bin; Yang Rui; Wang Sisheng; Shan Xiaobin; Qi Fei; Zhang Yunwu; Sheng Liusi; Hao Liqing; Zhou Shikang; Wang Zhenya

    2006-01-01

    Photoionization and dissociative photoionization of HFC-152a have been studied using synchrotron radiation and a reflection time-of-flight mass spectrometry (RTOF-MS). The ionization energy of parent molecule (11.94 ± 0.04 eV) and appearance potentials of various fragment ions have been determined by measuring their photoionization efficiency curves. Energies, symmetry point groups and ground electronic states of neutrals and cations of parent and its fragments have been calculated using GAUSSIAN-03 program with the G3 method. According to the theoretical and experimental results, some dissociation channels and their dissociation energies of CH 3 CHF 2 + have been analyzed. (authors)

  13. Development, Reliability, and Validity of a Child Dissociation Scale.

    Science.gov (United States)

    Putnam, Frank W.; And Others

    1993-01-01

    Evaluation of the Child Dissociative Checklist found it to be a reliable and valid observer report measure of dissociation in children, including sexually abused girls and children with dissociative disorder and with multiple personality disorder. The checklist, which is appended, is intended as a clinical screening instrument and research measure…

  14. The Contribution of Art Therapy to the Dissociative Disorders.

    Science.gov (United States)

    Murphy, Patricia S.

    1994-01-01

    Explored concepts of brain hemispheric lateralization and distinct right brain functioning in extensive dissociation by administering Dissociative Experiences Scale to 114 engineering students and 92 university drawing students. Chi-square calculation found differences in dissociative scoring levels between groups that approached significance at…

  15. VUV Study of Electron-Pyrimidine Dissociative Excitation

    Science.gov (United States)

    Hein, Jeff; Al-Khazraji, Hajar; Tiessen, Collin; Lukic, Dragan; Trocchi, Joshuah; McConkey, William

    2013-05-01

    A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of pyrimidine (C4H4N2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. Data have been made absolute using Lyman- α from H2 as a secondary standard. The main features in the spectrum are the H Lyman series lines. The emission cross section of Lyman- α is measured to be (2.44 +/- 0.25) 10-18 cm2 at 100 eV impact energy. The probability of extracting C or N atoms from the ring is shown to be very small. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.

  16. Dissociative sticking of CH4 on Ru(0001)

    DEFF Research Database (Denmark)

    Nielsen, Jane Hvolbæk; Holmblad, Peter Mikal; Chorkendorff, Ib

    1999-01-01

    In this study the CH4 dissociation probability on Ru(0001) is found for various translational and vibrational energies. The absolute sticking values are determined from King and Wells experiments and carbon uptake curves. The carbon amount is determined from the recombination signal of carbon...... with oxygen obtained after the beam exposure when heating in an oxygen atmosphere. The measured sticking coefficient of CH4 is strongly enhanced both by increasing the translational and the vibrational energy of the CH4 molecule. A model is applied to the data and an estimate of the thermal activation energy...

  17. A multi-reference singles and doubles configuration interaction determination in the dissociation energy and vibrational levels of the BeF molecules in the X2Σ + state

    International Nuclear Information System (INIS)

    Machado, F.B.C.; Ornellas, F.R.

    1988-10-01

    An accurate potential energy curve for the BeF molecule in the X 2 Σ + state is calculated within the MRSDCI approach. Vibrational level spacings and the dissociation energy are reported. Agreement with the available experimental spacings is 15 cm -1 on the average. The theoretically computed D o , 5.92 eV, favors the experimental value of 5.85 eV over the higher value of 6.26 eV. Arguments are also presented that show why the value obtained by the Birge-Sponer linear extrapolation is accidentally a good one. (author) [pt

  18. Predictors of trait dissociation and peritraumatic dissociation induced via cold pressor.

    Science.gov (United States)

    Gómez-Pérez, Lydia; López-Martínez, Alicia Eva; Asmundson, Gordon John Glenn

    2013-11-30

    Understanding which factors predict individual dissociative response during stressful situations is important to clarify the nature of dissociation and the mechanisms associated to its use as a coping strategy. The present study examined (1) whether experiential avoidance (EA), anxiety sensitivity (AS), depressive symptoms, and state anxiety concurrently predicted trait dissociation (TD)-absorption, amnesia, depersonalization, and total TD scores-and laboratory induced dissociation (LID); and (2) whether TD and catastrophizing predicted LID. We also examined whether catastrophizing mediated the relationships between both AS and depressive symptoms and LID. A total of 101 female undergraduate students participated in a cold pressor task, which significantly induced dissociation. Results of hierarchical regression analyses showed that AS at Time 1 (9 months before the experimental session), as well as depressive symptoms and catastrophizing at the time of the experiment (Time 2), predicted LID at Time 2. Depressive symptoms at Time 2 predicted total TD, absorption, and amnesia scores. AS at Time 1 and depressive symptoms at Time 2 predicted depersonalization. AS, depressive symptoms, and catastrophizing seem to facilitate the use of dissociative strategies by healthy individuals, even in response to non-traumatic but discomforting stress. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  19. Assessment of complex dissociative disorder patients and simulated dissociation in forensic contexts.

    Science.gov (United States)

    Brand, Bethany L; Webermann, Aliya R; Frankel, A Steven

    Few assessors receive training in assessing dissociation and complex dissociative disorders (DDs). Potential differential diagnoses include anxiety, mood, psychotic, substance use, and personality disorders, as well as exaggeration and malingering. Individuals with DDs typically elevate on many clinical and validity scales on psychological tests, yet research indicates that they can be distinguished from DD simulators. Becoming informed about the testing profiles of DD individuals and DD simulators can improve the accuracy of differential diagnoses in forensic settings. In this paper, we first review the testing profiles of individuals with complex DDs and contrast them with DD simulators on assessment measures used in forensic contexts, including the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), Personality Assessment Inventory (PAI), and the Structured Inventory of Reported Symptoms (SIRS), as well as dissociation-specific measures such as the Dissociative Experiences Scale (DES) and Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D-R). We then provide recommendations for assessing complex trauma and dissociation through the aforementioned assessments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Critical superheats upon boiling of dissociating liquids

    International Nuclear Information System (INIS)

    Kolykhan, L.I.; Solov'ev, V.N.

    1985-01-01

    The experimental data on critical superheats of dissociating liquids, i.e. nitrogen tetroxide and nitrine are presented (nitrine is the solution of nitrogen oxide in nitrogen tetroxide). The experiments with boiling N 2 O 4 have been carried out in the pressure range 0.1-3.0 MPa and with boiling nitrine within the pressure range 0.2-9.0 MPa. The experiments have revealed an anomalous dependence of critical superheats on pressure P, thus at P>=2.5 MPa the critical superheat values exceed the limiting ones, and at P=4.5 MPa this excess amounts to more than 16 K, essentially exceeding the errors of the experiments. The results for N 2 O 4 critical superheats agree with experimental data of other authors. Complex phenomena observed upon boiling of dissociating liquids require further theoretical and experimental studies

  1. Statistical modeling of competitive threshold collision-induced dissociation

    Science.gov (United States)

    Rodgers, M. T.; Armentrout, P. B.

    1998-08-01

    Collision-induced dissociation of (R1OH)Li+(R2OH) with xenon is studied using guided ion beam mass spectrometry. R1OH and R2OH include the following molecules: water, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. In all cases, the primary products formed correspond to endothermic loss of one of the neutral alcohols, with minor products that include those formed by ligand exchange and loss of both ligands. The cross-section thresholds are interpreted to yield 0 and 298 K bond energies for (R1OH)Li+-R2OH and relative Li+ binding affinities of the R1OH and R2OH ligands after accounting for the effects of multiple ion-molecule collisions, internal energy of the reactant ions, and dissociation lifetimes. We introduce a means to simultaneously analyze the cross sections for these competitive dissociations using statistical theories to predict the energy dependent branching ratio. Thermochemistry in good agreement with previous work is obtained in all cases. In essence, this statistical approach provides a detailed means of correcting for the "competitive shift" inherent in multichannel processes.

  2. Metastablity of the undissociated state of dissociated dislocations

    International Nuclear Information System (INIS)

    Takeuchi, Shin

    2005-01-01

    Undissociated, metastable dislocations have been observed in various crystals in addition to stable dissociated dislocations by high-resolution transmission electron microscopy. The origin of the metastablity of the undissociated state has been discussed specifically for the dissociation into Shockley partial dislocations in fcc or hcp lattice. It is shown that the metastability is due either to a high Peierls-Nabarro stress larger than a few percent of the shear modulus of the partial dislocations and/or to the increase of the total core energy by an increase of the dangling bonds. The metastablity of undissociated dislocations in zincblende III-V compounds is concluded to be due to a contribution of the latter effect

  3. Total dissociation cross section of halo nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Formanek, J. [Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni; Lombard, R.J. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire

    1996-10-01

    Calculations of the total dissociation cross section is performed in the impact parameter representation. The case of {sup 11}Be and {sup 11}Li loosing one and two neutron(s), respectively, by collision on a {sup 12}C target, which remains in its ground state are discussed. The results are found to depend essentially on the rms radius of the halo wave function. (author). 12 refs.

  4. Attempting to model dissociations of memory.

    Science.gov (United States)

    Reber, Paul J.

    2002-05-01

    Kinder and Shanks report simulations aimed at describing a single-system model of the dissociation between declarative and non-declarative memory. This model attempts to capture both Artificial Grammar Learning (AGL) and recognition memory with a single underlying representation. However, the model fails to reflect an essential feature of recognition memory - that it occurs after a single exposure - and the simulations may instead describe a potentially interesting property of over-training non-declarative memory.

  5. Laser ionization and dissociation of hydrogen

    International Nuclear Information System (INIS)

    Buck, J.D.

    1987-01-01

    Experiments undertaken to further characterize the spectroscopic and photophysical properties of some important excited singlet states of molecular hydrogen and its deuterium isotopes are described. Attention was centered on high vibrational levels of the B, C, and B' states within about 1000 cm -1 of the second dissociation limit. A double-resonance excitation scheme was needed to access levels with a large average bond distance from the ground state. Two-photon absorption of tunable uv-laser radiation-pumped ground-state hydrogen molecules into selected rovibronic levels of the metastable EF double-minimum electronic state. A second tunable near-IR probe laser was scanned to generate ions by resonant multiphoton ionization, where the resonant levels were provided by B, C, B', and other levels near the dissociation limit. New information was obtained regarding line shapes and intensities. Time-of-flight ion mass selection permitted observation of additional excitation channels with dissociation superimposed on the ionization process to produce protons

  6. Dissociated cultures of newborn mouse brain

    International Nuclear Information System (INIS)

    Wiesmann, U.N.; Hofmann, K.; Burkhart, T.; Herschkowitz, N.

    1975-01-01

    The metabolism of 35 SO 4 -sulfated lipids and mucopolysaccharides was studied in dissociated brain cell cultures from newborn albino mouse brains. The cultures were maintained under an atmosphere of 40% O 2 and 5% CO 2 in apparent good health up to 30 days. Early morphological examination of the dissociated cells demonstrated an initial partial reaggregation of the cells, which later settled and became confluent bilayered cultures. Cell proliferation measured by DNA and protein determination, morphological differentiation and biochemical differentiation took place in the dissociated brain cell cultures analogous in some respects to the in vivo situation. A timed increase in the synthesis of a myelin precursor, cerebroside 35 SO 4 , was observed after 6 to 8 days in culture (DIC). A peak of cerebroside sulfate was evident at 17 DIC. No stable sulfatide was observed at any time. Protein-bound macromolecular 35 SO 4 -MPS was synthetized and secreted from the cells into the culture medium. Maximal synthesis and secretion occurred at 8 DIC. This culture system proves to be a useful model for studying some aspects of differentiation of brain cells under external conditions. (author)

  7. Catalytic methanol dissociation

    International Nuclear Information System (INIS)

    Alcinikov, Y.; Fainberg, V.; Garbar, A.; Gutman, M.; Hetsroni, G.; Shindler, Y.; Tatrtakovsky, L.; Zvirin, Y.

    1998-01-01

    Results of the methanol dissociation study on copper/potassium catalyst with alumina support at various temperatures are presented. The following gaseous and liquid products at. The catalytic methanol dissociation is obtained: hydrogen, carbon monoxide, carbon dioxide, methane, and dimethyl ether. Formation rates of these products are discussed. Activation energies of corresponding reactions are calculated

  8. Kinetics and mechanism of the dissociation of chlorophyll and its metalloanalogues in proton-donating media

    International Nuclear Information System (INIS)

    Berezin, B.D.; Drobysheva, A.N.; Karmanova, L.P.

    1976-01-01

    The kinetics of the dissociation of chlorophyll a and its metalloanalogues (Zn 2+ and Cd 2+ complexes of chlorophyllic acid) have been investigated in t-butyl alcohol-trichloracetic acid mixtures. The dissociation reaction is kinetically firts-order with respect to the complex. The rate constants and the activation energies and entropies for the dissociation reaction have been calculated. In order to determine the order of the reaction with respect to the protogenic species, a study was made of the ionisation of m-nitroaniline in t-butyl alcohol at 25 0 C in the trichloroacetic acid concentration range from 0.15 to 4.75 M. The dissociation reaction of chlorophyll and its zinc-containing metalloanalogue has been shown to be of second order with respect to the solvated proton. The cadmium complex dissociates by a second-order reaction with respect to trichloroacetic acid

  9. Comparing the symptoms and mechanisms of "dissociation" in dissociative identity disorder and borderline personality disorder.

    Science.gov (United States)

    Laddis, Andreas; Dell, Paul F; Korzekwa, Marilyn

    2017-01-01

    A total of 75 patients were diagnosed with the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised as having dissociative identity disorder (DID), and 100 patients were diagnosed with the Structured Interview for DSM-IV Personality as having borderline personality disorder (BPD). Both groups were administered the Multidimensional Inventory of Dissociation (MID). DID patients had significantly higher MID scores than BPD patients, different distributions of MID scores, and different MID subscale profiles in 3 ranges of MID scores (0-15, 15-30, 30-45). The core MID symptoms-exhibited at all ranges of MID scores-for DID patients (the presence of alters, identity confusion, and memory problems) and BPD patients (flashbacks, identity confusion, and memory problems) were ostensibly similar but were considered to be mostly produced by different underlying processes. Multiple regression analyses showed that the core MID symptoms of DID patients had different predictors than did the core MID symptoms of BPD patients. Alter identities seemed to generate most-but not all-dissociative phenomena in DID patients, whereas only the 24% highest scoring BPD patients (MID ≥45) seemed to manifest alter-driven dissociative experiences. Most BPD dissociative experiences appeared to be due to 5 other mechanisms: (a) BPD-specific, stress-driven, rapid shifts of self-state; (b and c) nondefensive disruptions of the framework of perceptual organization with or without an accompanying BPD-specific, dissociation-like disintegration of affective/neurocognitive functioning; (d) a defensive distancing or detachment from distress (i.e., simple depersonalization); and (e) Allen, Console, and Lewis's (1999) severe absorptive detachment.

  10. Extension of CE/SE method to non-equilibrium dissociating flows

    KAUST Repository

    Wen, C.Y.; Saldivar Massimi, H.; Shen, Hua

    2017-01-01

    and quadrilateral elements. The dissociating and recombination chemical reactions as well as the vibrational energy relaxation are taken into account. The stiff source terms are solved by an implicit trapezoidal method of integration. Comparison with laboratory

  11. Vibrational and cascade dissociation of H{sub 2}{sup +} ions by collision with gas molecules; Dissociation vibrationnelle et dissociation en cascade d'ions H{sub 2}{sup +} par collisions avec les molecules d'un gaz

    Energy Technology Data Exchange (ETDEWEB)

    Verveer, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-07-01

    Protons produced by collisional dissociation of H{sub 2}{sup +} ions have an energy spectrum with a narrow central peak. For a part the protons in this peak are produced by vibrational dissociation and for another part by a cascade of two collisions. For H{sub 2}{sup +} ions of 50 to 150 keV the cross section for vibrational dissociation is about 4.1 10{sup -19} cm{sup 2}/molecule in hydrogen and 1.1 10{sup -18} cm{sup 2}/molecule in argon. (author) [French] Les protons resultant de la dissociation par collisions d'ions H{sub 2}{sup +} dans un gaz ont un spectre d'energie qui presente un pic central tres etroit. Les protons dans ce pic proviennent, pour une part de la dissociation vibrationnelle et pour l'autre part d'une suite de deux collisions. Dans le domaine d'energie des ions H{sub 2}{sup +} de 50 a 150 keV la section efficace de dissociation vibrationnel vaut 4.1 10{sup -19} cm{sup 2}/molecule pour l'hydrogene et 1,1 10{sup -18} cm{sup 2}/molecule pour l'argon.

  12. Dissociation of polycyclic aromatic hydrocarbons: molecular dynamics studies

    Science.gov (United States)

    Simon, A.; Rapacioli, M.; Rouaut, G.; Trinquier, G.; Gadéa, F. X.

    2017-03-01

    We present dynamical studies of the dissociation of polycyclic aromatic hydrocarbon (PAH) radical cations in their ground electronic states with significant internal energy. Molecular dynamics simulations are performed, the electronic structure being described on-the-fly at the self-consistent-charge density functional-based tight binding (SCC-DFTB) level of theory. The SCC-DFTB approach is first benchmarked against DFT results. Extensive simulations are achieved for naphthalene , pyrene and coronene at several energies. Such studies enable one to derive significant trends on branching ratios, kinetics, structures and hints on the formation mechanism of the ejected neutral fragments. In particular, dependence of branching ratios on PAH size and energy were retrieved. The losses of H and C2H2 (recognized as the ethyne molecule) were identified as major dissociation channels. The H/C2H2 ratio was found to increase with PAH size and to decrease with energy. For , which is the most interesting PAH from the astrophysical point of view, the loss of H was found as the quasi-only channel for an internal energy of 30 eV. Overall, in line with experimental trends, decreasing the internal energy or increasing the PAH size will favour the hydrogen loss channels with respect to carbonaceous fragments. This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.

  13. First-principles study of molecular NO dissociation on Ir(100) surface

    Science.gov (United States)

    Erikat, I. A.; Hamad, B. A.; Khalifeh, J. M.

    2014-02-01

    The dissociation of NO on Ir(100) surface is investigated using density functional theory (DFT). The pathway and transition state (TS) of the dissociation of NO molecule are determined using climbing image nudge elastic band (CI-NEB). The prerequisite state of NO dissociation is determining the most stable sites of the reactant and products. We found that the most energetically stable sites are the hollow for N atom and the bridge for NO molecule as well as O atom. We found that the bending of NO is the first step of the dissociation reaction due to the increase of the back-donation from the d-band of Ir to 2 π ∗ orbital of NO, which causes the weakening of NO bond. The dissociation energy barrier of NO molecule on Ir(100) surface is 0.49 eV.

  14. Electron-impact dissociative ionization of CClF3 and CCl3F

    International Nuclear Information System (INIS)

    Martinez, Roberto; Sierra, Borja; Basterretxea, Francisco J.; Sanchez Rayo, Maria N.; Castano, Fernando

    2006-01-01

    A crossed-beam experiment of well characterized kinetic energy (KE) electrons and supersonic halomethanes CCl 3 F and CClF 3 in Ar carrier has been carried out in order to quantify the kinetic energy distributions (KEDs), the appearance energies (AEs) and the channels involved in the production of nascent ions. The ion KEDs were derived from the band profiles of the time-of-flight mass spectrum and the total KEDs computed using conservation laws. Heavier ions are created with KED peaked at thermal energies in contrast with low mass atoms or other fragments, where the distribution is broader and the maximum is at much higher energies. A discussion of the dissociative ionization pathways derived from the appearance energies, total average KEDs, thermodynamic enthalpies and computed electron dissociation energies is reported. The role of the vibrational and rotational energies into the dissociative processes is also discussed

  15. [Questionnaire on dissociative symptoms. German adaptation, reliability and validity of the American Dissociative Experience Scale (DES)].

    Science.gov (United States)

    Freyberger, H J; Spitzer, C; Stieglitz, R D; Kuhn, G; Magdeburg, N; Bernstein-Carlson, E

    1998-06-01

    The "Fragebogen zu dissoziativen Symptomen (FDS)" represents the authorised German translation and adaptation of the "Dissociative Experience Scale" (DES; Bernstein and Putnam 1986). The original scale comprises 28 items covering dissociative experiences with regard to memory, identity, awareness and cognition according to DSM-III-R and DSM-IV. For the German version, 16 items were added to cover dissociative phenomena according to ICD-10, mainly pseudoneurological conversion symptoms. Reliability and validity of the German version were studied in a total sample of 813 persons and were compared to the results of the original version. Test-retest reliability of the FDS was rtt = 0.88 and Cronbach's consistency coefficient was alpha = 0.93, which is comparable to the results of the DES. The instrument differentiates between different samples (healthy control subjects, students, unselected neurological and psychiatric inpatients, neurological and psychiatric patients with a dissociative disorder and schizophrenics). The FDS is an easily applicable, reliable and valid measure to quantify dissociative experiences.

  16. GRAPHICAL DETERMINATION OF DISSOCIATION CONSTANT ...

    African Journals Online (AJOL)

    DR. AMINU

    conform to the general equation of straight – line graph; y = mx + c, where y = pH, m = slope, x = log. [HA]/[A] and C = intercept = pKa. Thus the pKa is obtained as the intercept of the graph of pH versus – log [HA]/[A] as shown in Figures 1,2 and 3 for glycine, alanine and valine respectively. The values obtained were 9.87 ...

  17. Comparison of electromagnetic and nuclear dissociation of 17Ne

    Science.gov (United States)

    Wamers, F.; Marganiec, J.; Aksouh, F.; Aksyutina, Yu.; Alvarez-Pol, H.; Aumann, T.; Beceiro-Novo, S.; Bertulani, C. A.; Boretzky, K.; Borge, M. J. G.; Chartier, M.; Chatillon, A.; Chulkov, L. V.; Cortina-Gil, D.; Emling, H.; Ershova, O.; Fraile, L. M.; Fynbo, H. O. U.; Galaviz, D.; Geissel, H.; Heil, M.; Hoffmann, D. H. H.; Hoffman, J.; Johansson, H. T.; Jonson, B.; Karagiannis, C.; Kiselev, O. A.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Langer, C.; Lantz, M.; Le Bleis, T.; Lehr, C.; Lemmon, R.; Litvinov, Yu. A.; Mahata, K.; Müntz, C.; Nilsson, T.; Nociforo, C.; Ott, W.; Panin, V.; Paschalis, S.; Perea, A.; Plag, R.; Reifarth, R.; Richter, A.; Riisager, K.; Rodriguez-Tajes, C.; Rossi, D.; Savran, D.; Schrieder, G.; Simon, H.; Stroth, J.; Sümmerer, K.; Tengblad, O.; Typel, S.; Weick, H.; Wiescher, M.; Wimmer, C.

    2018-03-01

    The Borromean drip-line nucleus 17Ne has been suggested to possess a two-proton halo structure in its ground state. In the astrophysical r p -process, where the two-proton capture reaction 15O(2 p ,γ )17Ne plays an important role, the calculated reaction rate differs by several orders of magnitude between different theoretical approaches. To add to the understanding of the 17Ne structure we have studied nuclear and electromagnetic dissociation. A 500 MeV/u 17Ne beam was directed toward lead, carbon, and polyethylene targets. Oxygen isotopes in the final state were measured in coincidence with one or two protons. Different reaction branches in the dissociation of 17Ne were disentangled. The relative populations of s and d states in 16F were determined for light and heavy targets. The differential cross section for electromagnetic dissociation (EMD) shows a continuous internal energy spectrum in the three-body system 15O+2 p . The 17Ne EMD data were compared to current theoretical models. None of them, however, yields satisfactory agreement with the experimental data presented here. These new data may facilitate future development of adequate models for description of the fragmentation process.

  18. Electromagnetic dissociation of relativistic [sup 28]Si by nucleon emission

    Energy Technology Data Exchange (ETDEWEB)

    Sonnadara, U.J.

    1992-12-01

    A detailed study of the electromagnetic dissociation of [sup 28]Si by nucleon emission at E[sub lab]/A = 14.6 (GeV/nucleon was carried out with [sup 28]Si beams interacting on [sup 208]Pb). [sup 120]Sn. [sup 64]C targets. The measurements apparatus consists of detectors in the target area which measure the energy and charged multiplicity, and a forward spectrometer which measures the position, momentum and energy of the reaction fragments. The exclusive electromagnetic dissociation cross sections for decay channels having multiple nucleons in the final state have been measured which enables the selection of events produced in pure electromagnetic interactions. The measured cross sections agree well with previous measurements obtained for the removal of a few nucleons as well as with measurements on total charge removal cross sections from other experiments. The dependence of the integrated cross sections on the target charge Z[sub T] and the target mass AT confirms that for higher Z targets the excitation is largely electromagnetic. Direct measurements of the excitation energy for the electromagnetic dissociation of [sup 28]Si [yields] p+[sup 27]Al and [sup 28]Si [yields] n+[sup 27]Si have been obtained through a calculation of the invariant mass in kinematically, reconstructed events. The excitation energy spectrum for all targets peak near the isovector giant dipole resonance in [sup 28]Si. These distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear [sup 28]Si([sub [gamma],p])[sup 27]Al and [sup 28]Si([sub [gamma],n])[sup 27]Si. The possibilities of observing double giant dipole resonance excitations in [sup 28]Si have been investigated with cross section measurements as well as with excitation energy reconstruction.

  19. Dissociation and memory fragmentation in post-traumatic stress disorder: an evaluation of the dissociative encoding hypothesis.

    Science.gov (United States)

    Bedard-Gilligan, Michele; Zoellner, Lori A

    2012-01-01

    Several prominent theories of post-traumatic stress disorder (PTSD) posit that peritraumatic dissociation results in insufficient encoding of the trauma memory and that persistent dissociation prevents memory elaboration, resulting in memory fragmentation and PTSD. In this review we summarise the empirical literature on peritraumatic and trait dissociation and trauma narrative fragmentation as measured by meta-memory and rater/objective coding. Across 16 studies to date, the association between dissociation and fragmentation was most prominent when examining peritraumatic dissociation and patient's own ratings of memory fragmentation. This relationship did not hold when examining trait dissociation or rater-coded or computer-generated measures of fragmentation. Thus initial evidence points more towards a strong self-reported association between constructs that is not supported on more objective fragmentation coding. Measurement overlap, construct ambiguity, and exclusion of potential confounds may underlie lack of a strong association between dissociation and objective-rated fragmentation.

  20. Absolute total and partial dissociative cross sections of pyrimidine at electron and proton intermediate impact velocities

    Energy Technology Data Exchange (ETDEWEB)

    Wolff, Wania, E-mail: wania@if.ufrj.br; Luna, Hugo; Sigaud, Lucas; Montenegro, Eduardo C. [Instituto de Física, Universidade Federal do Rio de Janeiro, PO 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Tavares, Andre C. [Departamento de Física, Pontificia Universidade Católica do Rio de Janeiro, PO 38071, Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, RJ (Brazil)

    2014-02-14

    Absolute total non-dissociative and partial dissociative cross sections of pyrimidine were measured for electron impact energies ranging from 70 to 400 eV and for proton impact energies from 125 up to 2500 keV. MOs ionization induced by coulomb interaction were studied by measuring both ionization and partial dissociative cross sections through time of flight mass spectrometry and by obtaining the branching ratios for fragment formation via a model calculation based on the Born approximation. The partial yields and the absolute cross sections measured as a function of the energy combined with the model calculation proved to be a useful tool to determine the vacancy population of the valence MOs from which several sets of fragment ions are produced. It was also a key point to distinguish the dissociation regimes induced by both particles. A comparison with previous experimental results is also presented.

  1. Systematics of 2-body diffractive dissociations and search of double diffractive dissociation in K-p interactions at 14.3 GeV/c

    International Nuclear Information System (INIS)

    Pons, Yvette.

    1977-12-01

    The diffractive dissociation mechanism is shown to be general when looking at 22 mesonic or baryonic threshold enhancements. The dissociation systems are all produced peripherally and present the property of slope-mass correlation. The production slopes and cross-sections mainly depend on the diffractive excitation mass. The comparison of the results with those from the I.S.R. shows that dissociation systems are very similar in their effective mass shape, momentum transfer structure and angular distributions at center-of-mass energies differing by a factor of ten. Evidence for double diffractive dissociation mechanism is found in 2 exclusive reactions at a cross section level of 5-10+-2 μb. The factorisation hypothesis seems well verified [fr

  2. Isomerization and dissociation in competition: the two-component dissociation rates of methyl acetate ions

    Science.gov (United States)

    Mazyar, Oleg A.; Mayer, Paul M.; Baer, Tomas

    1997-11-01

    Threshold photoelectron-photoion coincidence (TPEPICO) spectroscopy has been used to investigate the unimolecular chemistry of metastable methyl acetate ions, CH3COOCH3.+. The rate of molecular ion fragmentation with the loss of CH3O. and CH2OH radicals as a function of ion internal energy was obtained from the coincidence data and used in conjunction with Rice-Ramsperger-Kassel-Markus and ab initio molecular orbital calculations to model the dissociation/isomerization mechanism of the methyl acetate ion (A). The data were found to be consistent with the mechanism involving a hydrogen-bridged complex CH3CO[middle dot][middle dot][middle dot]H[middle dot][middle dot][middle dot]OCH2.+(E) as the direct precursor of the observed fragments CH3CO+ and CH2OH.. The two-component decay rates were modeled with a three-well-two-product potential energy surface including the distonic ion CH3C(OH)OCH2.+(B) and enol isomer CH2C(OH)OCH3.+(C), which are formed from the methyl acetate ion by two consecutive [1,4]-hydrogen shifts. The 0 K heats of formation of isomers B and C as well as transition states TSAB, TSBC, and TSBE (relative to isomer A) were calculated from Rice-Ramsperger-Kassel-Markus (RRKM) theory.

  3. Water dissociating on rigid Ni(100): A quantum dynamics study on a full-dimensional potential energy surface

    Science.gov (United States)

    Liu, Tianhui; Chen, Jun; Zhang, Zhaojun; Shen, Xiangjian; Fu, Bina; Zhang, Dong H.

    2018-04-01

    We constructed a nine-dimensional (9D) potential energy surface (PES) for the dissociative chemisorption of H2O on a rigid Ni(100) surface using the neural network method based on roughly 110 000 energies obtained from extensive density functional theory (DFT) calculations. The resulting PES is accurate and smooth, based on the small fitting errors and the good agreement between the fitted PES and the direct DFT calculations. Time dependent wave packet calculations also showed that the PES is very well converged with respect to the fitting procedure. The dissociation probabilities of H2O initially in the ground rovibrational state from 9D quantum dynamics calculations are quite different from the site-specific results from the seven-dimensional (7D) calculations, indicating the importance of full-dimensional quantum dynamics to quantitatively characterize this gas-surface reaction. It is found that the validity of the site-averaging approximation with exact potential holds well, where the site-averaging dissociation probability over 15 fixed impact sites obtained from 7D quantum dynamics calculations can accurately approximate the 9D dissociation probability for H2O in the ground rovibrational state.

  4. The responses of dissociative patients on the thematic apperception test.

    Science.gov (United States)

    Pica, M; Beere, D; Lovinger, S; Dush, D

    2001-07-01

    This study compared the responses of dissociative inpatients and general inpatient psychiatric controls on the Thematic Apperception Test (TAT; Murray, 1943). We found the stories of dissociative participants to be characterized by a greater interpersonal distance and more trauma and dissociation responses than those of the controls. No significant differences were found regarding total number of emotional references, although references to positive emotions were almost nonexistent for the dissociative group. A post hoc analysis of the data found the testing behaviors of dissociative participants to be characterized by switching, trance states, intrainterview amnesias, and affectively loaded card rejections. Questions were raised regarding the relevancy of the findings to clinical practice and how they might explain some of the controversies surrounding the diagnosis of dissociative identity disorder (DID). Copyright 2001 John Wiley & Sons, Inc.

  5. Quantum entanglement and the dissociation process of diatomic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Esquivel, Rodolfo O; Molina-Espiritu, Moyocoyani [Departamento de Quimica, Universidad Autonoma Metropolitana, 09340-Mexico DF (Mexico); Flores-Gallegos, Nelson [Unidad Profesional Interdisciplinaria de IngenierIa, Campus Guanajuato del Instituto Politecnico Nacional, 36275-Guanajuato (Mexico); Plastino, A R; Angulo, Juan Carlos; Dehesa, Jesus S [Instituto Carlos I de Fisica Teorica y Computacional, and Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, 18071-Granada (Spain); Antolin, Juan, E-mail: esquivel@xanum.uam.mx, E-mail: arplastino@ugr.es [Departamento de Fisica Aplicada, EUITIZ, Universidad de Zaragoza, 50018-Zaragoza (Spain)

    2011-09-14

    In this work, we investigate quantum entanglement-related aspects of the dissociation process of some selected, representative homo- and heteronuclear diatomic molecules. This study is based upon high-quality ab initio calculations of the (correlated) molecular wavefunctions involved in the dissociation processes. The values of the electronic entanglement characterizing the system in the limit cases corresponding to (i) the united-atom representation and (ii) the asymptotic region when atoms dissociate are discussed in detail. It is also shown that the behaviour of the electronic entanglement as a function of the reaction coordinate R exhibits remarkable correspondences with the phenomenological description of the physically meaningful regimes comprising the processes under study. In particular, the extrema of the total energies and the electronic entanglement are shown to be associated with the main physical changes experienced by the molecular spatial electronic density, such as charge depletion and accumulation or bond cleavage regions. These structural changes are characterized by several selected descriptors of the density, such as the Laplacian of the electronic molecular distributions (LAP), the molecular electrostatic potential (MEP) and the atomic electric potentials fitted to the MEP.

  6. Predictions of hydrate plug dissociation with electrical heating

    Energy Technology Data Exchange (ETDEWEB)

    Davies, S.R.; Ivanic, J.; Sloan, E.D.

    2005-07-01

    The rate of dissociation for cylindrical hydrate plugs by the application of radial electrical heating was investigated for structure I and structure II hydrates for pressures of 7 MPa (1000 psia) and 14 MPa (2000 psia). Heating rates of 2.3 kWm{sup -3}, 4.5 kWm-3 and 6.8 kWm{sup -3} were investigated for a plug 91.4 cm (36 inches) in length and 2.54 cm (1 inch) in diameter. A heat transfer model was developed in cylindrical coordinates based on Fourier's Law with a boundary condition of constant heat flux at the pipe wall. The equation set was solved numerically using a finite difference grid and the standard explicit scheme. The model was found to replicate well the experimental observations with no fitted parameters. A computer program was formulated to allow the practicing engineer to simulate the dissociation of industrial hydrates with minimal complexity. This program was incorporated into the latest version of our CSMPlug program which has been used by a number of energy companies to predict hydrate plug dissociation rates in the field. (Author)

  7. Fracture-dissociation of ceramic liner.

    Science.gov (United States)

    Hwang, Sung Kwan; Oh, Jin-Rok; Her, Man Seung; Shim, Young Jun; Cho, Tae Yeun; Kwon, Sung Min

    2008-08-01

    The use of BIOLOX delta ceramic (CeramTec AG, Plochingen, Germany) has been increasing. This ceramic prevents cracking by restraining the phase transformation due to the insertion of nano-sized, yttria-stabilized tetragonal zirconia into the alumina matrix. This restrains the progress of cracking through the formation of platelet-like crystal or whiskers due to the addition of an oxide additive. We observed a case of BIOLOX delta ceramic liner (CeramTec AG) rim fracture 4 months postoperatively. Radiographs showed that the ceramic liner was subluxated from the acetabular cup. Scratches on the acetabular cup and femoral neck were seen, and the fracture was visible on the rim of the liner. Under electron microscope, metal particle coatings from the ceramic liner were identified. The ceramic liner, fracture fragments, and adjacent tissues were removed and replaced with a ceramic liner and femoral head of the same size and design. We believe the mechanism of the fracture-dissociation of the ceramic liner in this case is similar to a case of separation of the ceramic liner from the polyethylene shell in a sandwich-type ceramic-ceramic joint. To prevent ceramic liner fracture-dissociation, the diameter of the femoral neck needs to be decreased in a new design, while the diameter of the femoral head needs to be increased to ensure an increase in range of motion.

  8. Contextual Treatment of Dissociative Identity Disorder.

    Science.gov (United States)

    Gold, Steven N; Elhai, Jon D; Rea, Bayard D; Weiss, Donna; Masino, Theodore; Morris, Staci Leon; McIninch, Jessica

    2001-01-01

    Evidence for the effectiveness of contextual therapy, a new approach for treating adult survivors of prolonged child abuse (PCA), is provided via case studies of three women with Dissociative Identity Disorder (DID). Contextual therapy is based on the premise that it is not only traumatic experiences that account for PCA survivors' psychological difficulties. Even more fundamentally, many survivors grow up in an interpersonal context in which adequate resources for secure attachment and acquisition of adaptive living skills are not available. As a result, they are left with lasting deficits that undermine not only their current functioning, but also their ability to cope with reliving their traumatic memories in therapy. The primary focus of this treatment approach, therefore, is on developing capacities for feeling and functioning better in the present, rather than on extensive exploration and processing of the client's trauma history or, in the case of DID, of identity fragments. Treatment of the three cases presented ranged from eight months to two and one-half years' duration, and culminated in very positive outcomes. The women's reports of achievements, such as obtaining and maintaining gainful employment, greater self-sufficiency, and the establishment of more intimate and gratifying relationships, indicated marked improvements in daily functioning. Objective test data obtained at admission and discharge, and in one case, at follow-up, documented substantial reductions in dissociative, posttraumatic stress, depressive, and other symptoms.

  9. Mechanical Dissociation of Retinal Neurons with Vibration

    Science.gov (United States)

    Motomura, Tamami; Hayashida, Yuki; Murayama, Nobuki

    The neuromorphic device, which implements the functions of biological neural circuits by means of VLSI technology, has been collecting much attention in the engineering fields in the last decade. Concurrently, progress in neuroscience research has revealed the nonlinear computation in single neuron levels, suggesting that individual neurons are not merely the circuit elements but computational units. Thus, elucidating the properties of neuronal signal processing is thought to be an essential step for developing the next generation of neuromorphic devices. In the present study, we developed a method for dissociating single neurons from specific sublayers of mammalian retinas with using no proteolytic enzymes but rather combining tissue incubation in a low-Ca2+ medium and the vibro-dissociation technique developed for the slices of brains and spinal cords previously. Our method took shorter time of the procedure, and required less elaborated skill, than the conventional enzymatic method did; nevertheless it yielded enough number of the cells available for acute electrophysiological experiments. The isolated retinal neurons were useful for measuring the nonlinear membrane conductances as well as the spike firing properties under the perforated-patch whole-cell configuration. These neurons also enabled us to examine the effects of proteolytic enzymes on the membrane excitability in those cells.

  10. Alkali promotion of N-2 dissociation over Ru(0001)

    DEFF Research Database (Denmark)

    Mortensen, Jens Jørgen; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Using self-consistent density functional calculations, we show that adsorbed Na and Cs lower the barrier for dissociation of N2 on Ru(0001). Since N2 dissociation is a crucial step in the ammonia synthesis reaction, we explain in this way the experimental observation that alkali metals promote th...... the ammonia synthesis reaction over Ru catalysts. We also show that the origin of this effect is predominantly a direct electrostatic attraction between the adsorbed alkali atoms and the dissociating molecule....

  11. Microstructural and analytical analysis of plasma dissociated zircon

    International Nuclear Information System (INIS)

    Minnaar, E G; Neethling, J H; Lee, M E; Snyders, E

    2012-01-01

    The investigation of the microstructure and distribution of impurities was carried out on plasma dissociated zircon (PDZ). The morphology of the PDZ and crystalline nature of the zirconia was determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) while energy dispersive X-ray spectrometry (EDS) provided compositional information. The SEM and TEM results indicate that the morphology and crystalline nature of the zirconia varies as a result of the existence of a thermal gradient. The EDS results show that the majority of the impurities segregates to the silica phase of the PDZ.

  12. Multidimensional effects on dissociation of N-2 on Ru(0001)

    DEFF Research Database (Denmark)

    Diaz, C.; Vincent, J.K.; Krishnamohan, G.P.

    2006-01-01

    on density functional theory. The computed reaction probabilities are in good agreement with molecular beam experiments. Comparison to previous calculations shows that the rotation of N-2 and its motion along the surface affect the reactivity of N-2 much more than nonadiabatic effects.......The applicability of the Born-Oppenheimer approximation to molecule-metal surface reactions is presently a topic of intense debate. We have performed classical trajectory calculations on a prototype activated dissociation reaction, of N-2 on Ru(0001), using a potential energy surface based...

  13. Multiple Personality and the Pathological Dissociation of Self.

    Science.gov (United States)

    Price, Reese E.

    This paper considers the condition of Multiple Personality Disorder (MPD), which is defined as a separation of alternating personalities by rigid boundaries and amnestic barriers. It is proposed that MPD represents the end of a continuum of a defensive dissociation of the self that can result when a child employs a dissociative splitting of self…

  14. Coulomb dissociation of {sup 8}B at 254 A MeV

    Energy Technology Data Exchange (ETDEWEB)

    Suemmerer, K; Boue, F; Baumann, T; Geissel, H; Hellstroem, M; Koczon, P; Schwab, E; Schwab, W; Senger, P; Surowiecz, A [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Iwasa, N; Ozawa, A [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); [RIKEN Institute of Physical and Chemical Research, Saitama (Japan); Surowka, G [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); [Jagiellonian Univ., Krakow (Poland). Inst. of Physics; Blank, B; Czajkowski, S; Marchand, C; Pravikoff, M S [Centre d` Etudes Nucleaires de Bordeaux-Gradignan, 33 (France); Foerster, A; Lauer, F; Oeschler, H; Speer, J; Sturm, C; Uhlig, F; Wagner, A [Technische Univ. Darmstadt (Germany); Gai, M [Connecticut Univ., Storrs, CT (United States). Dept. of Physics; Grosse, E [Inst. fuer Kern- und Hadronenphysik, Forschungszentrum Rossendorf, Dresden (Germany); Kohlmeyer, B [Philipps Univ., Marburg (Germany). Fachbereich Physik; Kulessa, R; Walus, W [Jagiellonian Univ., Krakow (Poland). Inst. of Physics; Motobayashi, T [Rikkyo Univ., Tokyo (Japan). Dept. of Physics; Teranishi, T [RIKEN Institute of Physical and Chemical Research, Saitama (Japan)

    1998-06-01

    As an alternative method for determining the astrophysical S-factor for the {sup 7}Be(p,{gamma}){sup 8}B reaction we have measured the Coulomb dissociation of {sup 8}B at 254 A MeV. From our preliminary results, we obtain good agreement with both the accepted direct-reaction measurements and the low-energy Coulomb dissociation study of Iwasa et al. performed at about 50 A MeV. (orig.)

  15. Thermal dissociation and unfolding of insulin

    DEFF Research Database (Denmark)

    Huus, Kasper; Havelund, Svend; Olsen, Helle B

    2005-01-01

    The thermal stability of human insulin was studied by differential scanning microcalorimetry and near-UV circular dichroism as a function of zinc/protein ratio, to elucidate the dissociation and unfolding processes of insulin in different association states. Zinc-free insulin, which is primarily...... dimeric at room temperature, unfolded at approximately 70 degrees C. The two monomeric insulin mutants Asp(B28) and Asp(B9),Glu(B27) unfolded at higher temperatures, but with enthalpies of unfolding that were approximately 30% smaller. Small amounts of zinc caused a biphasic thermal denaturation pattern...... of insulin. The biphasic denaturation is caused by a redistribution of zinc ions during the heating process and results in two distinct transitions with T(m)'s of approximately 70 and approximately 87 degrees C corresponding to monomer/dimer and hexamer, respectively. At high zinc concentrations (>or=5 Zn(2...

  16. Characterization of Neutral Radicals from a Dissociative Electron Attachment Process

    Science.gov (United States)

    Li, Zhou; Milosavljević, Aleksandar R.; Carmichael, Ian; Ptasinska, Sylwia

    2017-08-01

    Despite decades of gas-phase studies on dissociative electron attachment (DEA) to various molecules, as yet there has been no direct detection and characterization of the neutral radical species produced by this process. In this study, we performed stepwise electron spectroscopy to directly measure and characterize the neutrals produced upon zero-electron-energy DEA to the model molecule, carbon tetrachloride (CCl4 ). We observed the direct yield of the trichloromethyl radical (CCl3. ) formed by DEA to CCl4 and measured the appearance energies of all the other neutral species. By combining these experimental findings with high-level quantum chemical calculations, we performed a complete analysis of both the DEA to CCl4 and the subsequent electron-impact ionization of CCl3. . This work paves the way toward a complete experimental characterization of DEA processes, which will lead to a better understanding of the low-energy electron-induced formation of radical species.

  17. Mechanisms of Coupled Vibrational Relaxation and Dissociation in Carbon Dioxide.

    Science.gov (United States)

    Armenise, Iole; Kustova, Elena

    2018-05-21

    A complete vibrational state-specific kinetic scheme describing dissociating carbon dioxide mixtures is proposed. CO 2 symmetric, bending and asymmetric vibrations and dissociation-recombination are strongly coupled through inter-mode vibrational energy transfers. Comparative study of state-resolved rate coefficients is carried out; the effect of different transitions may vary considerably with temperature. A non-equilibrium 1-D boundary layer flow typical to hypersonic planetary entry is studied in the state-to-state approach. To assess the sensitivity of fluid-dynamic variables and heat transfer to various vibrational transitions and chemical reactions, corresponding processes are successively included to the kinetic scheme. It is shown that vibrational-translational (VT) transitions in the symmetric and asymmetric modes do not alter the flow and can be neglected whereas the VT 2 exchange in the bending mode is the main channel of vibrational relaxation. Inter-mode vibrational exchanges affect the flow implicitly, through energy redistribution enhancing VT relaxation; the dominating role belongs to near-resonant transitions between symmetric and bending modes as well as between CO molecules and CO 2 asymmetric mode. Strong coupling between VT 2 relaxation and chemical reactions is emphasized. While vibrational distributions and average vibrational energy show strong dependence on the kinetic scheme, the heat flux is more sensitive to chemical reactions.

  18. The Dual Role of Disorder on the Dissociation of Interfacial Charge Transfer Excitons

    Science.gov (United States)

    Shi, Liang; Lee, Chee-Kong; Willard, Adam

    In organic-based photovoltaics (OPV), dissociation of neutral photo-excitations (i.e., Frenkel excitons) into free charge carriers requires the excitons to overcome binding energy that can significantly exceed thermal energies. The inability of bound charges to overcome this large binding energy has been implicated as a primary source of efficiency loss in OPVs. Despite the potential impact on the performance of organic solar cells much remains to be understood about the microscopic mechanism of exciton dissociation in OPV materials. Here we explore the role of static molecular disorder in mediating this charge dissociation process. Using a simple lattice model of exciton dynamics we demonstrate that random spatial variations in the energetic landscape can mitigate the effects of the exciton binding energy by lowering the free energy barrier. By considering the competition between this thermodynamic effect and the disorder-induced slowing of dissociation kinetics we demonstrate that exciton dissociation yields are expected to depend non-monotonically on the degree of static disorder. We conclude that a certain amount of molecular-scale disorder is desirable in order to optimize the performance of organic photovoltaic materials.

  19. Errors of Logic and Scholarship Concerning Dissociative Identity Disorder

    Science.gov (United States)

    Ross, Colin A.

    2009-01-01

    The author reviewed a two-part critique of dissociative identity disorder published in the "Canadian Journal of Psychiatry". The two papers contain errors of logic and scholarship. Contrary to the conclusions in the critique, dissociative identity disorder has established diagnostic reliability and concurrent validity, the trauma histories of…

  20. Retrospective review of lumbosacral dissociations in blast injuries.

    Science.gov (United States)

    Helgeson, Melvin D; Lehman, Ronald A; Cooper, Patrick; Frisch, Michael; Andersen, Romney C; Bellabarba, Carlo

    2011-04-01

    Retrospective review of medical records and radiographs. We assessed the clinical outcomes of lumbosacral dissociation (LSD) after traumatic, combat-related injuries, and to review our management of these distinct injuries and report our preliminary follow-up. LSD injuries are an anatomic separation of the pelvis from the spinal column, and are the result of high-energy trauma. A relative increase in these injuries has been seen in young healthy combat casualties subjected to high-energy blast trauma. We performed a retrospective review of inpatient/outpatient medical records and radiographs for all patients treated at our institution with combat-related lumbosacral dissociations. Twenty-three patients met inclusion criteria of combat-related lumbosacral dissociations with one-year follow-up. Patients were treated as follows: no fixation (9), sacroiliac screw fixation (8), posterior spinal fusion (5) and sacral plate (1). All patients with radiographic evidence of a zone III sacral fracture, in addition to associated lumbar fractures indicating loss of the iliolumbar ligamentous complex integrity were included. In 15 patients, the sacral fracture were an H or U type zone III fracture, whereas in the remaining nine, the sacral fracture was severely comminuted and unable to classify (six open fractures). There was no difference in visual analog scale (VAS) between treatment modalities. Two open injuries had residual infections. One patient treated with an L4-ilium posterior spinal fusion with instrumentation required instrumentation removal for infection. At a mean follow-up of 1.71 years (range, 1-4.5), 11 patients (48%) still reported residual pain and the mean VAS at latest follow-up was 1.7 (range, 0-7). Operative stabilization promoted healing and earlier mobilization, but carries a high-postoperative risk of infection. Nonoperative management should be considered in patients whose comorbidities prevent safe stabilization.

  1. Early Indicators of Pathological Dissociation in Sexually Abused Children.

    Science.gov (United States)

    McElroy, Linda Provus

    1992-01-01

    This paper reviews factors in the professional neglect of multiple personality disorder (MPD) and sexual abuse in childhood, as well as recent diagnostic developments in childhood dissociative disorders. The identification of subtle dissociative symptomatology in children is illustrated, and two case examples are presented. (Author)

  2. Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds

    Directory of Open Access Journals (Sweden)

    Ibon Alkorta

    2017-10-01

    Full Text Available It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N2, CO, HC≡CH, CH2=CH2, C3H6, PH3, H2S, HCN, H2O, H2CO and NH3 and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H2O, F2, Cl2, Br2, ClF, BrCl, H3SiF, H3GeF, F2CO, CO2, N2O, NO2F, PH2F, AsH2F, SO2, SeO2, SF2, and SeF2 can be represented to good approximation by means of the equation D e = c ′ N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ′ is a constant, conveniently chosen to have the value 1.00 kJ mol−1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1 the hydrogen bond; (2 the halogen bond; (3 the tetrel bond; (4 the pnictogen bond; and (5 the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

  3. Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds.

    Science.gov (United States)

    Alkorta, Ibon; Legon, Anthony C

    2017-10-23

    It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N₂, CO, HC≡CH, CH₂=CH₂, C₃H₆, PH₃, H₂S, HCN, H₂O, H₂CO and NH₃) and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H₂O, F₂, Cl₂, Br₂, ClF, BrCl, H₃SiF, H₃GeF, F₂CO, CO₂, N₂O, NO₂F, PH₂F, AsH₂F, SO₂, SeO₂, SF₂, and SeF₂) can be represented to good approximation by means of the equation D e = c ' N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ' is a constant, conveniently chosen to have the value 1.00 kJ mol -1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1) the hydrogen bond; (2) the halogen bond; (3) the tetrel bond; (4) the pnictogen bond; and (5) the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

  4. The rise and fall of dissociative identity disorder.

    Science.gov (United States)

    Paris, Joel

    2012-12-01

    Dissociative identity disorder (DID), once considered rare, was frequently diagnosed during the 1980s and 1990s, after which interest declined. This is the trajectory of a medical fad. DID was based on poorly conceived theories and used potentially damaging treatment methods. The problem continues, given that the DSM-5 includes DID and accords dissociative disorders a separate chapter in its manual.

  5. Cross Sections for Electron-Impact Dissociation of Alternative Etching Gas, C3HF7O

    Science.gov (United States)

    Tanaka, Hideyuki; Toyoda, Hirotaka; Sugai, Hideo

    1998-09-01

    The search for alternative for perfluorocarbon gases from the environmental point of view has resulted in a new etching gas, C3HF7O (1,2,2,2-tetrafluoroethyl-trifluoromethyl ether, abbreviated as HFE-227). In this paper, the first measurement of the absolute cross sections for the dissociation of HFE-227, is reported.The neutral dissociation is measured from the threshold to 250 eV by appearance mass spectrometry in a dual electron beam device.The threshold energies for the neutral dissociation into CF, CF2 and CF3 are 14.7, 12.5 and 11.2 eV, respectively.The cross sections for the dissociation from HFE-227 into CF3 and CF are larger than those from c-C4F8 (octafluorocyclobutane), but not for the dissociation into CF2.Besides the neutral dissociation, the cross sections for the dissociative ionization of HFE-227 are extensively measured for the formation of twelve ionic species, i.e., CO+, CHO+, CF+, CHF+, CFO+, CF2+, CHF2+, CF3+, CHF3+, C2HF2O+, C2HF4+ and C2HF4O+.

  6. Site selective dissociation of ozone upon core excitation

    International Nuclear Information System (INIS)

    Mocellin, A.; Mundim, M.S.P.; Coutinho, L.H.; Homem, M.G.P.; Naves de Brito, A.

    2007-01-01

    We present new measurements applied to core excitation of ozone molecule using to analyze the dissociation channels the photo-electron-photo-ion coincidence (PEPICO) and the photo-electron-photo-ion-photo-ion coincidence (PEPIPICO) technique. The new experimental set-up allows measuring O + /O + ion pair coincidences without discrimination. The dissociation channels of several core-excited states have been investigated. The relative yields of dissociation channels were determined from coincidence data. The core excitation from O terminal (O T ) or O central (O C ) induce different fragmentation; preferentially one bond is broken at the O terminal excitation and two bonds when O central is excited, showing site selectivity fragmentation of ozone upon core excitation. The ultra-fast dissociation of the O T 1s -1 7a 1 1 core-excited state is confirmed by the relative yield of dissociation

  7. Site selective dissociation of ozone upon core excitation

    Energy Technology Data Exchange (ETDEWEB)

    Mocellin, A. [Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil)], E-mail: mocellin@fis.unb.br; Mundim, M.S.P. [Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil); Coutinho, L.H. [Instituto de Quimica, Universidade Federal do Rio de Janeiro-UFRJ, Box 68563, CEP 21945-970, Rio de Janeiro-RJ (Brazil); Homem, M.G.P. [Laboratorio Nacional de Luz Sincrotron-LNLS, Box 6192, CEP 13084-971, Campinas-SP (Brazil); Naves de Brito, A. [Laboratorio Nacional de Luz Sincrotron-LNLS, Box 6192, CEP 13084-971, Campinas-SP (Brazil); Instituto de Fisica, Universidade de Brasilia-UnB, Box 04455, CEP 70919-970, Brasilia-DF (Brazil)

    2007-05-15

    We present new measurements applied to core excitation of ozone molecule using to analyze the dissociation channels the photo-electron-photo-ion coincidence (PEPICO) and the photo-electron-photo-ion-photo-ion coincidence (PEPIPICO) technique. The new experimental set-up allows measuring O{sup +}/O{sup +} ion pair coincidences without discrimination. The dissociation channels of several core-excited states have been investigated. The relative yields of dissociation channels were determined from coincidence data. The core excitation from O terminal (O{sub T}) or O central (O{sub C}) induce different fragmentation; preferentially one bond is broken at the O terminal excitation and two bonds when O central is excited, showing site selectivity fragmentation of ozone upon core excitation. The ultra-fast dissociation of the O{sub T} 1s{sup -1}7a{sub 1}{sup 1} core-excited state is confirmed by the relative yield of dissociation.

  8. Symmetry Breakdown in Ground State Dissociation of HD+

    International Nuclear Information System (INIS)

    Ben-Itzhak, I.; Wells, E.; Carnes, K. D.; Krishnamurthi, Vidhya; Weaver, O. L.; Esry, B. D.

    2000-01-01

    Experimental studies of the dissociation of the electronic ground state of HD + following ionization of HD by fast proton impact indicate that the H + +D 1s dissociation channel is more likely than the H1s+D + dissociation channel by about 7% . This isotopic symmetry breakdown is due to the finite nuclear mass correction to the Born-Oppenheimer approximation which makes the 1sσ state 3.7 meV lower than the 2pσ state at the dissociation limit. The measured fractions of the two dissociation channels are in agreement with coupled-channels calculations of 1sσ to 2pσ transitions. (c) 2000 The American Physical Society

  9. Parents' descriptions of young children's dissociative reactions after trauma.

    Science.gov (United States)

    Cintron, Gabriela; Salloum, Alison; Blair-Andrews, Zoe; Storch, Eric A

    2017-10-09

    There is limited research on the phenomenology of how young children who have been exposed to trauma express the intrusive symptom of dissociative reactions. The current qualitative study utilized interviews from a semi-structured diagnostic clinical interview with 74 caregivers of young children (ages 3 to 7) who were exposed to trauma to identify parents' descriptions of their children's dissociative reactions during a clinical interview. Based on results from the interview, 45.9% of the children had dissociative reactions (8.5% had flashbacks and 41.9% had dissociative episodes). Interviews were transcribed to identify themes of dissociative reactions in young children. Common themes to flashbacks and dissociative episodes included being triggered, being psychologically in their own world (e.g., spaced out and shut down), and displaying visible signs (e.g., crying and screaming). For flashbacks, caregivers reported that it seemed as if the child was re-experiencing the trauma (e.g., yelling specific words and having body responses). For dissociative episodes, caregivers noted that the child not only seemed psychologically somewhere else (e.g., distant and not there) but also would be physically positioned somewhere else (e.g., sitting and not responding). Caregivers also expressed their own reactions to the child's dissociative episode due to not understanding what was occurring, and trying to interrupt the occurrences (e.g., calling out to the child). Themes, descriptions, and phrases to describe dissociative reactions in young children after trauma can be used to help parents and professionals more accurately identify occurrences of dissociative reactions.

  10. Testing the diagnosis of dissociative identity disorder through measures of dissociation, absorption, hypnotizability and PTSD: a Norwegian pilot study.

    Science.gov (United States)

    Dale, Karl Yngvar; Berg, Renate; Elden, Ake; Ødegård, Atle; Holte, Arne

    2009-01-01

    A total of 14 women meeting criteria for dissociative identity disorder (DID) based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]) were compared to a group of women (n = 10) with other dissociative diagnoses and a group of normal controls (n = 14) with regard to dissociativity, absorption, trauma related symptoms and hypnotizability. Both of the clinical groups reported histories of childhood trauma and attained high PTSD scores. The DID group differed significantly from the group with other dissociative diagnoses and the non-diagnosed comparison group with regard to hypnotizability, the variety of dissociative symptomatology, and the magnitude of dissociative symptomatology. However, no significant differences between the two clinical groups were detected with regard to absorption, general dissociative level, or symptoms related to traumatic stress. Results support the notion that DID can be regarded as a clinical entity which is separable from other dissociative disorders. Results also indicated that hypnotizability is the most important clinical feature of DID.

  11. Communication: Methane dissociation on Ni(111) surface: Importance of azimuth and surface impact site

    International Nuclear Information System (INIS)

    Shen, Xiangjian; Zhang, Zhaojun; Zhang, Dong H.

    2016-01-01

    Understanding the role of reactant ro-vibrational degrees of freedom (DOFs) in reaction dynamics of polyatomic molecular dissociation on metal surfaces is of great importance to explore the complex chemical reaction mechanism. Here, we present an expensive quantum dynamics study of the dissociative chemisorption of CH 4 on a rigid Ni(111) surface by developing an accurate nine-dimensional quantum dynamical model including the DOF of azimuth. Based on a highly accurate fifteen-dimensional potential energy surface built from first principles, our simulations elucidate that the dissociation probability of CH 4 has the strong dependence on azimuth and surface impact site. Some improvements are suggested to obtain the accurate dissociation probability from quantum dynamics simulations.

  12. Low-energy electron-induced dissociation in gas-phase nicotine, pyridine, and methyl-pyrrolidine

    Science.gov (United States)

    Ryszka, Michal; Alizadeh, Elahe; Li, Zhou; Ptasińska, Sylwia

    2017-09-01

    Dissociative electron attachment to nicotine, pyridine, and N-methyl-pyrrolidine was studied in the gas phase in order to assess their stability with respect to low-energy electron interactions. Anion yield curves for different products at electron energies ranging from zero to 15 eV were measured, and the molecular fragmentation pathways were proposed. Nicotine does not form a stable parent anion or a dehydrogenated anion, contrary to other biological systems. However, we have observed complex dissociation pathways involving fragmentation at the pyrrolidine side accompanied by isomerization mechanisms. Combining structure optimization and enthalpy calculations, performed with the Gaussian09 package, with the comparison with a deuterium-labeled N-methyl-d3-pyrrolidine allowed for the determination of the fragmentation pathways. In contrast to nicotine and N-methylpyrrolidine, the dominant pathway in dissociative electron attachment to pyridine is the loss of hydrogen, leading to the formation of an [M—H]- anion. The presented results provide important new information about the stability of nicotine and its constituent parts and contribute to a better understanding of the fragmentation mechanisms and their effects on the biological environment.

  13. Multireference configuration interaction treatment of potential energy surfaces: symmetric dissociation of H/sub 2/O in a double-zeta basis

    Energy Technology Data Exchange (ETDEWEB)

    Brown, F B; Shavitt, I; Shepard, R

    1984-03-23

    Multiconfiguration self-consistent fields (SCF) and multireference configurational interaction (CI) calculations have been performed for the H/sub 2/O molecule in a double-zeta basis for four symmetric geometries, for comparison with full CI results. Unlike single-reference results, the energy errors are almost independent of geometry, allowing unbiased treatments of potential energy surfaces. 35 references, 1 figure, 2 tables.

  14. Electron Transfer Dissociation and Collision-Induced Dissociation of Underivatized Metallated Oligosaccharides

    Science.gov (United States)

    Schaller-Duke, Ranelle M.; Bogala, Mallikharjuna R.; Cassady, Carolyn J.

    2018-05-01

    Electron transfer dissociation (ETD) and collision-induced dissociation (CID) were used to investigate underivatized, metal-cationized oligosaccharides formed via electrospray ionization (ESI). Reducing and non-reducing sugars were studied including the tetrasaccharides maltotetraose, 3α,4β,3α-galactotetraose, stachyose, nystose, and a heptasaccharide, maltoheptaose. Univalent alkali, divalent alkaline earth, divalent and trivalent transition metal ions, and a boron group trivalent metal ion were adducted to the non-permethylated oligosaccharides. ESI generated [M + Met]+, [M + 2Met]2+, [M + Met]2+, [M + Met - H]+, and [M + Met - 2H]+ most intensely along with low intensity nitrate adducts, depending on the metal and sugar ionized. The ability of these metal ions to produce oligosaccharide adduct ions by ESI had the general trend: Ca(II) > Mg(II) > Ni(II) > Co(II) > Zn(II) > Cu(II) > Na(I) > K(I) > Al(III) ≈ Fe(III) ≈ Cr(III). Although trivalent metals were utilized, no triply charged ions were formed. Metal cations allowed for high ESI signal intensity without permethylation. ETD and CID on [M + Met]2+ produced various glycosidic and cross-ring cleavages, with ETD producing more cross-ring and internal ions, which are useful for structural analysis. Product ion intensities varied based on glycosidic-bond linkage and identity of monosaccharide sub-unit, and metal adducts. ETD and CID showed high fragmentation efficiency, often with complete precursor dissociation, depending on the identity of the adducted metal ion. Loss of water was occasionally observed, but elimination of small neutral molecules was not prevalent. For both ETD and CID, [M + Co]2+ produced the most uniform structurally informative dissociation with all oligosaccharides studied. The ETD and CID spectra were complementary. [Figure not available: see fulltext.

  15. Electron Transfer Dissociation and Collision-Induced Dissociation of Underivatized Metallated Oligosaccharides

    Science.gov (United States)

    Schaller-Duke, Ranelle M.; Bogala, Mallikharjuna R.; Cassady, Carolyn J.

    2018-02-01

    Electron transfer dissociation (ETD) and collision-induced dissociation (CID) were used to investigate underivatized, metal-cationized oligosaccharides formed via electrospray ionization (ESI). Reducing and non-reducing sugars were studied including the tetrasaccharides maltotetraose, 3α,4β,3α-galactotetraose, stachyose, nystose, and a heptasaccharide, maltoheptaose. Univalent alkali, divalent alkaline earth, divalent and trivalent transition metal ions, and a boron group trivalent metal ion were adducted to the non-permethylated oligosaccharides. ESI generated [M + Met]+, [M + 2Met]2+, [M + Met]2+, [M + Met - H]+, and [M + Met - 2H]+ most intensely along with low intensity nitrate adducts, depending on the metal and sugar ionized. The ability of these metal ions to produce oligosaccharide adduct ions by ESI had the general trend: Ca(II) > Mg(II) > Ni(II) > Co(II) > Zn(II) > Cu(II) > Na(I) > K(I) > Al(III) ≈ Fe(III) ≈ Cr(III). Although trivalent metals were utilized, no triply charged ions were formed. Metal cations allowed for high ESI signal intensity without permethylation. ETD and CID on [M + Met]2+ produced various glycosidic and cross-ring cleavages, with ETD producing more cross-ring and internal ions, which are useful for structural analysis. Product ion intensities varied based on glycosidic-bond linkage and identity of monosaccharide sub-unit, and metal adducts. ETD and CID showed high fragmentation efficiency, often with complete precursor dissociation, depending on the identity of the adducted metal ion. Loss of water was occasionally observed, but elimination of small neutral molecules was not prevalent. For both ETD and CID, [M + Co]2+ produced the most uniform structurally informative dissociation with all oligosaccharides studied. The ETD and CID spectra were complementary. [Figure not available: see fulltext.

  16. Electromagnetic field effects on Υ-meson dissociation in PbPb collisions at LHC energies

    Energy Technology Data Exchange (ETDEWEB)

    Hoelck, J.; Wolschin, G. [Institut fuer Theoretische Physik der Universitaet Heidelberg (Germany)

    2017-12-15

    We investigate the effect of the electromagnetic field generated in relativistic heavy-ion collisions on the dissociation of Υ mesons. The electromagnetic field is calculated using a simple model which characterizes the emerging quark-gluon plasma (QGP) by its conductivity only. A numerical estimate of the field strength experienced by Υ mesons embedded in the expanding QGP and its consequences on the Υ dissociation is made. The electromagnetic field effects prove to be negligible compared to the established strong-interaction suppression mechanisms. (orig.)

  17. Dissociative Photoionization of 1-Halogenated Silacyclohexanes: Silicon Traps the Halogen.

    Science.gov (United States)

    Bodi, Andras; Sigurdardottir, Katrin Lilja; Kvaran, Ágúst; Bjornsson, Ragnar; Arnason, Ingvar

    2016-11-23

    The threshold photoelectron spectra and threshold photoionization mass spectra of 1-halogenated-1-silacyclohexanes, for the halogens X = F, Cl, Br, and I, have been obtained using synchrotron vacuum ultraviolet radiation and photoelectron photoion coincidence spectroscopy. As confirmed by a similar ionization onset and density functional theory molecular orbitals, the ionization to the ground state is dominated by electron removal from the silacyclohexane ring for X = F, Cl, and Br, and from the halogen lone pair for X = I. The breakdown diagrams show that the dissociative photoionization mechanism is also different for X = I. Whereas the parent ions decay by ethylene loss for X = F to Br in the low-energy regime, the iodine atom is lost for X = I. The first step is followed by a sequential ethylene loss at higher internal energies in each of the compounds. It is argued that the tendency of silicon to lower bond angles stabilizes the complex cation in which C 2 H 4 is η 2 -coordinated to it, and which precedes ethylene loss. Together with the relatively strong silicon-halogen bonds and the increased inductive effect of the silacyclohexane ring in stabilizing the cation, this explains the main differences observed in the fragmentation of the halogenated silacyclohexane and halogenated cyclohexane ions. The breakdown diagrams have been modeled taking into account slow dissociations at threshold and the resulting kinetic shift. The 0 K appearance energies have been obtained to within 0.08 eV for the ethylene loss for X = F to Br (10.56, 10.51, and 10.51 eV, respectively), the iodine atom loss for X = I (10.11 eV), the sequential ethylene loss for X = F to I (12.29, 12.01, 11.94, and 11.86 eV, respectively), and the minor channels of H loss for X = F (10.56 eV) and propylene loss in X = Cl (also at 10.56 eV). The appearance energies for the major channels likely correspond to the dissociative photoionization reaction energy.

  18. Dissociative, depressive, and PTSD symptom severity as correlates of nonsuicidal self-injury and suicidality in dissociative disorder patients.

    Science.gov (United States)

    Webermann, Aliya R; Myrick, Amie C; Taylor, Christina L; Chasson, Gregory S; Brand, Bethany L

    2016-01-01

    The present study investigates whether symptom severity can distinguish patients diagnosed with dissociative identity disorder and dissociative disorder not otherwise specified with a recent history of nonsuicidal self-injury (NSSI) and suicide attempts from those patients without recent self-harm. A total of 241 clinicians reported on recent history of patient NSSI and suicide attempts. Of these clinicians' patients, 221 completed dissociative, depressive, and posttraumatic stress disorder symptomatology measures. Baseline cross-sectional data from a naturalistic and prospective study of dissociative disorder patients receiving community treatment were utilized. Analyses evaluated dissociative, depressive, and posttraumatic stress disorder symptom severity as methods of classifying patients into NSSI and suicide attempt groupings. Results indicated that dissociation severity accurately classified patients into NSSI and suicidality groups, whereas depression severity accurately classified patients into NSSI groups. These findings point to dissociation and depression severity as important correlates of NSSI and suicidality in patients with dissociative disorders and have implications for self-harm prevention and treatment.

  19. First-principles study of H2 adsorption and dissociation on Zr(0 0 0 1)

    International Nuclear Information System (INIS)

    Zhang Peng; Wang Shuangxi; Zhao Jian; He Chaohui; Zhang Ping

    2011-01-01

    Highlights: → The stability of the equilibrium adsorption states is determined after the geometry optimization. → The origin of the stable chemisorbed state is analyzed by the electronic structure and charge redistribution calculation. → The dissociation energetics of H2 are investigated in details by the PES and CINEB calculation. - Abstract: The adsorption and dissociation of H 2 molecules on the Zr(0 0 0 1) surface are systematically investigated by using density functional theory within the generalized gradient approximation and a supercell approach. After geometry optimization, the most stable equilibrium adsorption state is found to be along the top-y entrance. By calculating the adiabatic potential energy surface, the chemisorbed molecular adsorption states are also identified to be along the parallel channel at the top site. The electronic properties of the stable chemisorbed molecular state are analyzed, which show that the interaction between the molecule and substrate is of covalent characteristic with a sizeable charge redistribution. On the other hand, the hcp site is turned out to be the most stable equilibrium adsorption site for hydrogen atom on Zr(0 0 0 1) surface after the dissociation of H 2 . The dissociation energetics of H 2 are studied by calculating the potential energy surface and the minimum energy path of the transition state is determined by using the climb image nudged elastic band method, wherein the fcc-y channel is found to be most stable and favorable for dissociative adsorption of H 2 among the five possible dissociative paths. Remarkably, we find that the adiabatic dissociation process of H 2 is an activated type but with a small energy barrier, which is well consistent with the macroscopic phenomenon that the zirconium metal is easily hydrogenated.

  20. Psychological Dissection of Patients Having Dissociative Disorder: A Cross-sectional Study.

    Science.gov (United States)

    Reddy, Lohit Somashekar; Patil, N M; Nayak, Raghavendra B; Chate, Sameeran S; Ansari, Saba

    2018-01-01

    Patients present with dissociative disorders as a decompensation to underlying stressful situation. It is clinically important to evaluate the presence, type, and temporal relation of the stressors resulting in dissociation. Further knowing the sociodemographic and psychological profile of the dissociative patient helps in better management. The study included 55 dissociative patients aged between 5 to 45 years. Psychiatric diagnosis was made using ICD-10 DCR. Psychosocial stressors and stressful life events were assessed using presumptive stressful life events scale/life events scale for Indian children and clinical interview. Personality and temperament traits were assessed using medico psychological questionnaire and temperament measurement schedule, respectively. Intelligence quotient (IQ) was assessed using standard progressive matrices and colored progressive matrices. Statistical analysis was done using Epi Info 7 software. All patients had significant psychosocial stressors preceding dissociation. Precipitating factor with temporal association was observed in only 83.64%. Family disharmony (41.82%) followed by education-related problems (29.09%) was the most common psychosocial stressors. 61.82% of the dissociative patients had psychiatric comorbidity. Mean IQ of study sample was 92.47. Dissociative children had high emotionality and energy levels but low sociability, rhythmicity, and distractibility. 50% of the adults were neurotic and had emotionally unstable personality. Dissociative disorders are commonly seen in females, adolescents, and in those from lower socioeconomic status and rural areas. They are always preceded by psychosocial stressors. Most of them have comorbid psychiatric disorders such as depression and anxiety. Neuroticism and emotionally unstable personality traits are common in adult patients while temperamental traits such as low sociability, low rhythmicity, low distractibility, high emotionality, and high energy levels are common in

  1. Effect of the electrodynamic structure of a microwave discharge in air on the efficiency of oxygen dissociation

    International Nuclear Information System (INIS)

    Akhmedzhanov, R.A.; Vikharev, A.L.; Gorbachov, A.M.; Ivanov, O.A.; Kolysko, A.L.

    1997-01-01

    From experimental measurements and numerical calculations of oxygen dissociation in a nanosecond microwave (MW) discharge in air, the dependance is obtained of the energy cost for the production of an oxygen atom on the electrodynamic structure and parameters of the discharge. Oxygen dissociation is shown to be most efficient when high-power MW pulses are used. On the basis of numerical calculations of the energy cost for oxygen for dissociation in a MW discharge created at altitudes of the ozone layer in the earth's atmosphere, a conclusion is made about the possibility of using MW discharges for effective compensation of the ozone loss in a local ''oxide hole.''

  2. Errors of logic and scholarship concerning dissociative identity disorder.

    Science.gov (United States)

    Ross, Colin A

    2009-01-01

    The author reviewed a two-part critique of dissociative identity disorder published in the Canadian Journal of Psychiatry. The two papers contain errors of logic and scholarship. Contrary to the conclusions in the critique, dissociative identity disorder has established diagnostic reliability and concurrent validity, the trauma histories of affected individuals can be corroborated, and the existing prospective treatment outcome literature demonstrates improvement in individuals receiving psychotherapy for the disorder. The available evidence supports the inclusion of dissociative identity disorder in future editions of the Diagnostic and Statistical Manual of Mental Disorders.

  3. Dissociation of recombinant prion autocatalysis from infectivity.

    Science.gov (United States)

    Noble, Geoffrey P; Supattapone, Surachai

    2015-01-01

    Within the mammalian prion field, the existence of recombinant prion protein (PrP) conformers with self-replicating (ie. autocatalytic) activity in vitro but little to no infectious activity in vivo challenges a key prediction of the protein-only hypothesis of prion replication--that autocatalytic PrP conformers should be infectious. To understand this dissociation of autocatalysis from infectivity, we recently performed a structural and functional comparison between a highly infectious and non-infectious pair of autocatalytic recombinant PrP conformers derived from the same initial prion strain. (1) We identified restricted, C-terminal structural differences between these 2 conformers and provided evidence that these relatively subtle differences prevent the non-infectious conformer from templating the conversion of native PrP(C) substrates containing a glycosylphosphatidylinositol (GPI) anchor. (1) In this article we discuss a model, consistent with these findings, in which recombinant PrP, lacking post-translational modifications and associated folding constraints, is capable of adopting a wide variety of autocatalytic conformations. Only a subset of these recombinant conformers can be adopted by post-translationally modified native PrP(C), and this subset represents the recombinant conformers with high specific infectivity. We examine this model's implications for the generation of highly infectious recombinant prions and the protein-only hypothesis of prion replication.

  4. Water dissociation on Ni(100) and Ni(111): Effect of surface temperature on reactivity

    International Nuclear Information System (INIS)

    Seenivasan, H.; Tiwari, Ashwani K.

    2013-01-01

    Water adsorption and dissociation on Ni(100) and Ni(111) surfaces are studied using density functional theory calculations. Water adsorbs on top site on both the surfaces, while H and OH adsorb on four fold hollow and three fold hollow (fcc) sites on Ni(100) and Ni(111), respectively. Transition states (TS) on both surfaces are identified using climbing image-nudged elastic band method. It is found that the barrier to dissociation on Ni(100) surface is slightly lower than that on Ni(111) surface. Dissociation on both the surfaces is exothermic, while the exothermicity on Ni(100) is large. To study the effect of lattice motion on the energy barrier, TS calculations are performed for various values of Q (lattice atom coordinate along the surface normal) and the change in the barrier height and position is determined. Calculations show that the energy barrier to reaction decreases with increasing Q and increases with decreasing Q on both the surfaces. Dissociation probability values at different surface temperatures are computed using semi-classical approximation. Results show that the influence of surface temperature on dissociation probability on the Ni(100) is significantly larger compared to that of Ni(111). Moreover, on Ni(100), a dramatic shift in energy barrier to lower incident energy values is observed with increasing surface temperature, while the shift is smaller in the case of Ni(111)

  5. Visuomotor Dissociation in Cerebral Scaling of Size.

    Science.gov (United States)

    Potgieser, Adriaan R E; de Jong, Bauke M

    2016-01-01

    Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in which 16 right-handed subjects copied geometric figures while the result of drawing remained out of sight. Either the size of the example figure varied while maintaining a constant size of drawing (visual incongruity) or the size of the examples remained constant while subjects were instructed to make changes in size (motor incongruity). These incongruent were compared to congruent conditions. Statistical Parametric Mapping (SPM8) revealed brain activations related to size incongruity in the dorsolateral prefrontal and inferior parietal cortex, pre-SMA / anterior cingulate and anterior insula, dominant in the right hemisphere. This pattern represented simultaneous use of a 'resized' virtual template and actual picture information requiring spatial working memory, early-stage attention shifting and inhibitory control. Activations were strongest in motor incongruity while right pre-dorsal premotor activation specifically occurred in this condition. Visual incongruity additionally relied on a ventral visual pathway. Left ventral premotor activation occurred in all variably sized drawing while constant visuomotor size, compared to congruent size variation, uniquely activated the lateral occipital cortex additional to superior parietal regions. These results highlight size as a fundamental parameter in both general hand movement and movement guided by objects perceived in the context of surrounding 3D space.

  6. Visuomotor Dissociation in Cerebral Scaling of Size.

    Directory of Open Access Journals (Sweden)

    Adriaan R E Potgieser

    Full Text Available Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in which 16 right-handed subjects copied geometric figures while the result of drawing remained out of sight. Either the size of the example figure varied while maintaining a constant size of drawing (visual incongruity or the size of the examples remained constant while subjects were instructed to make changes in size (motor incongruity. These incongruent were compared to congruent conditions. Statistical Parametric Mapping (SPM8 revealed brain activations related to size incongruity in the dorsolateral prefrontal and inferior parietal cortex, pre-SMA / anterior cingulate and anterior insula, dominant in the right hemisphere. This pattern represented simultaneous use of a 'resized' virtual template and actual picture information requiring spatial working memory, early-stage attention shifting and inhibitory control. Activations were strongest in motor incongruity while right pre-dorsal premotor activation specifically occurred in this condition. Visual incongruity additionally relied on a ventral visual pathway. Left ventral premotor activation occurred in all variably sized drawing while constant visuomotor size, compared to congruent size variation, uniquely activated the lateral occipital cortex additional to superior parietal regions. These results highlight size as a fundamental parameter in both general hand movement and movement guided by objects perceived in the context of surrounding 3D space.

  7. Strong-field dissociation dynamics

    International Nuclear Information System (INIS)

    DiMauro, L.F.; Yang, Baorui.

    1993-01-01

    The strong-field dissociation behavior of diatomic molecules is examined under two distinctive physical scenarios. In the first scenario, the dissociation of the isolated hydrogen and deuterium molecular ions is discussed. The dynamics of above-threshold dissociation (ATD) are investigated over a wide range of green and infrared intensities and compared to a dressed-state model. The second situation arises when strong-field neutral dissociation is followed by ionization of the atomic fragments. The study results in a direct measure of the atomic fragment's ac-Stark shift by observing the intensity-dependent shifts in the electron or nuclear fragment kinetic energy. 8 figs., 14 refs

  8. Ionic diffusion and salt dissociation conditions of lithium liquid crystal electrolytes.

    Science.gov (United States)

    Saito, Yuria; Hirai, Kenichi; Murata, Shuuhei; Kishii, Yutaka; Kii, Keisuke; Yoshio, Masafumi; Kato, Takashi

    2005-06-16

    Salt dissociation conditions and dynamic properties of ionic species in liquid crystal electrolytes of lithium were investigated by a combination of NMR spectra and diffusion coefficient estimations using the pulsed gradient spin-echo NMR techniques. Activation energies of diffusion (Ea) of ionic species changed with the phase transition of the electrolyte. That is, Ea of the nematic phase was lower than that of the isotropic phase. This indicates that the aligned liquid crystal molecules prepared efficient conduction pathways for migration of ionic species. The dissociation degree of the salt was lower compared with those of the conventional electrolyte solutions and polymer gel electrolytes. This is attributed to the low concentration of polar sites, which attract the dissolved salt and promote salt dissociation, on the liquid crystal molecules. Furthermore, motional restriction of the molecules due to high viscosity and molecular oriented configuration in the nematic phase caused inefficient attraction of the sites for the salt. With a decreased dissolved salt concentration of the liquid crystal electrolyte, salt dissociation proceeded, and two diffusion components attributed to the ion and ion pair were detected independently. This means that the exchange rate between the ion and the ion pair is fairly slow once the salt is dissociated in the liquid crystal electrolytes due to the low motility of the medium molecules that initiate salt dissociation.

  9. Structure sensitivity of CO dissociation on Rh surfaces

    DEFF Research Database (Denmark)

    Mavrikakis, Manos; Baumer, M.; Freund, H.J.

    2002-01-01

    than the flat surface, but the effect is considerably weaker than the effect of surface structure on the dissociation barrier. Our findings are compared with available experimental data, and the consequences for CO activation in methanation and Fischer-Tropsch reactions are discussed.......Using periodic self-consistent density functional calculations it is shown that the barrier for CO dissociation is similar to120 kJ/mol lower on the stepped Rh(211) surface than on the close-packed Rh(111) surface. The stepped surface binds molecular CO and the dissociation products more strongly...

  10. Ionisation and dissociation of water induced by swift multicharged ions

    International Nuclear Information System (INIS)

    Legendre, S.

    2006-02-01

    Ionization and dissociation of water molecules and water clusters induced by 11.7 MeV/A Ni 25+ ions were carried out by imaging techniques. Branching ratios, ionisation cross sections and Kinetic Energy Released distributions have been measured together with fragmentation dynamics studies. Multiple ionization represents approximately 30% of the ionizing events. Double ionization produces in significant way atomic oxygen, considered as a possible precursor of the large production of HO 2 radical in liquid water radiolysis by ions of high Linear Energy Transfer. We evidence a strong selectivity of bond breakage in the case of ion-induced HOD fragmentation. Once the molecule doubly ionized, the breakage of the O-H bond is found 6.5 times more probable than that of the O-D bond. A semi-classical calculation simulating the fragmentation dynamics on the potential energy surface of the ground-state of di-cation H 2 O 2+ makes possible to as well reproduce the preferential nature of the breakage of the O-H bond as the position and the shift of the kinetic energy distributions. First results concerning interaction with water clusters are also reported. Measurements in coincidence are carried out giving access to correlation, with the distributions in energy and angle of the emitted fragments. Mass spectrum points fast intra-cluster proton transfer, leading to the emission of protonated clusters. (author)

  11. Remote control of the dissociative ionization of H2 based on electron-H2 + entanglement

    Science.gov (United States)

    Wang, Jun-Ping; He, Feng

    2018-04-01

    The single ionization of H2 in strong laser fields creates the correlated electron-H2 + pair. Based on such a correlation, we conceive a strategy to control the energy spectra of the freed electron or dissociative fragments by simulating the time-dependent Schrödinger equation. Two attosecond pulses in a train produce the replica of electron-H2 + pairs, which are to be steered by a time-delayed phase-stabilized (mid)infrared laser pulse. By controlling the behavior of the freed electron, the dissociation of H2 + can be controlled even though there is no direct laser-H2 + coupling. On the other hand, the photoelectron energy spectra can be manipulated via laser-H2 + coupling. This study demonstrates the entanglement of molecular quantum wave packets, and affords a route to remotely control molecular dissociative ionization.

  12. Dissociative Recombination and Excitation of CH+5 : Absolute Cross Sections and Branching Fractions

    International Nuclear Information System (INIS)

    Semaniak, J.; Larson, A.; Le Padellec, A.; Stroemholm, C.; Larsson, M.; Rosen, S.; Peverall, R.; Danared, H.; Djuric, N.; Dunn, G.H.; Datz, S.

    1998-01-01

    The heavy-ion storage ring CRYRING was used to measure the absolute dissociative recombination and dissociative excitation cross sections for collision energies below 50 eV. Deduced thermal rates coefficients are consistent with previous beams data but are lower by a factor of 3 than the rates measured by means of the flowing afterglow Langmuir probe technique. A resonant structure in dissociative recombination cross section was found at 9 eV. We have determined the branching fractions in DR of CH + 5 below 0.2 eV. The branching is dominated by three-body CH 3 + H + H and CH 2 + H 2 + H dissociation channels, which occur with branching ratios of ∼0.7 and ∼0.2, respectively; thus methane is a minor species among dissociation products. Both the measured absolute cross sections and branching in dissociative recombination of CH + 5 can have important implications for the models of dense interstellar clouds and abundance of CH 2 , CH 3 and CH 4 in these media. copyright copyright 1998. The American Astronomical Society

  13. Spectroscopic constants and potential energy curve of the iodine weakly bound 1u state correlating with the I(2P1/2) + I(2P1/2) dissociation limit

    International Nuclear Information System (INIS)

    Akopyan, M E; Baturo, V V; Lukashov, S S; Poretsky, S A; Pravilov, A M

    2015-01-01

    The stepwise three-step three-color laser population of the I 2 (β1 g , ν β , J β ) rovibronic states via the B0 u + , ν B , J B rovibronic states and rovibronic levels of the 1 u (bb) and 0 g + (bb) states mixed by hyperfine interaction is used for determination of rovibronic level energies of the weakly bound I 2 (1 u (bb)) state. Dunham coefficients of the state, Y i0 (i = 0–3), Y i1 (i = 0–2), Y 02 and Y 12 for the v 1 u  = 1–5, 8, 10, 15 and J 1 u  ≈ 9–87 ranges, the dissociation energy of the state, D e , and equilibrium I–I distance, R e , as well as the potential energy curve are determined. There are aperiodicities in the excitation spectrum corresponding to the β, ν β  = 23, J β  ← 1 u (bb), ν 1u  = 4, 5, J 1u progressions in the I 2  + Rg = He, Ar mixture, namely, a great number of lines which do not coincide with the R or P line progressions. Their positions conflict with the ΔJ-even selection rule. Furthermore, they do not correspond to the ΔJ-odd progression. (paper)

  14. Memories of attachment hamper EEG cortical connectivity in dissociative patients.

    Science.gov (United States)

    Farina, Benedetto; Speranza, Anna Maria; Dittoni, Serena; Gnoni, Valentina; Trentini, Cristina; Vergano, Carola Maggiora; Liotti, Giovanni; Brunetti, Riccardo; Testani, Elisa; Della Marca, Giacomo

    2014-08-01

    In this study, we evaluated cortical connectivity modifications by electroencephalography (EEG) lagged coherence analysis, in subjects with dissociative disorders and in controls, after retrieval of attachment memories. We asked thirteen patients with dissociative disorders and thirteen age- and sex-matched healthy controls to retrieve personal attachment-related autobiographical memories through adult attachment interviews (AAI). EEG was recorded in the closed eyes resting state before and after the AAI. EEG lagged coherence before and after AAI was compared in all subjects. In the control group, memories of attachment promoted a widespread increase in EEG connectivity, in particular in the high-frequency EEG bands. Compared to controls, dissociative patients did not show an increase in EEG connectivity after the AAI. Conclusions: These results shed light on the neurophysiology of the disintegrative effect of retrieval of traumatic attachment memories in dissociative patients.

  15. Complete-active-space second-order perturbation theory (CASPT2//CASSCF) study of the dissociative electron attachment in canonical DNA nucleobases caused by low-energy electrons (0-3 eV)

    Energy Technology Data Exchange (ETDEWEB)

    Francés-Monerris, Antonio; Segarra-Martí, Javier; Merchán, Manuela; Roca-Sanjuán, Daniel, E-mail: Daniel.Roca@uv.es [Instituto de Ciencia Molecular, Universitat de València, P.O. Box 22085, 46071 València (Spain)

    2015-12-07

    Low-energy (0-3 eV) ballistic electrons originated during the irradiation of biological material can interact with DNA/RNA nucleobases yielding transient-anion species which undergo decompositions. Since the discovery that these reactions can eventually lead to strand breaking of the DNA chains, great efforts have been dedicated to their study. The main fragmentation at the 0-3 eV energy range is the ejection of a hydrogen atom from the specific nitrogen positions. In the present study, the methodological approach introduced in a previous work on uracil [I. González-Ramírez et al., J. Chem. Theory Comput. 8, 2769-2776 (2012)] is employed to study the DNA canonical nucleobases fragmentations of N–H bonds induced by low-energy electrons. The approach is based on minimum energy path and linear interpolation of internal coordinates computations along the N–H dissociation channels carried out at the complete-active-space self-consistent field//complete-active-space second-order perturbation theory level. On the basis of the calculated theoretical quantities, new assignations for the adenine and cytosine anion yield curves are provided. In addition, the π{sub 1}{sup −} and π{sub 2}{sup −} states of the pyrimidine nucleobases are expected to produce the temporary anions at electron energies close to 1 and 2 eV, respectively. Finally, the present theoretical results do not allow to discard neither the dipole-bound nor the valence-bound mechanisms in the range of energies explored, suggesting that both possibilities may coexist in the experiments carried out with the isolated nucleobases.

  16. Thermodynamic analysis of the Cu2S-Cu2Te system using dissociation pressure data

    International Nuclear Information System (INIS)

    Glazov, V.M.; Pashinkin, A.S.; Burkhanov, A.S.; Saleeva, N.M.

    1978-01-01

    The Knudsen effusive method has been used for studying the dissociation pressure in the Cu 2 S-Cu 2 Te system, and on the basis of the experimental data obtained, the tellurium activity in the system and the mixing energy have been calculated. The dissociation pressure of pure components and alloys containing 10, 30, 50, 70, and 90 mol% of copper telluride within the temperature range of 750-1200 deg C has been studied. A smooth character of the concentration dependence of tellurium activity is observed, which points to the formation of a continuous series of solid solutions in the Cu 2 S-Cu 2 Te system within the temperature range studied. The data on the mixing energy in the system show a good agreement of the values obtained from the dissociation pressure with those determined from the fusibility diagram. The results indicate that the system in question is described well within the framework of the model of regular solutions

  17. Trajectory dynamics study of the Ar + CH4 dissociation reaction at high temperatures: the importance of zero-point-energy effects.

    Science.gov (United States)

    Marques, J M C; Martínez-Núñez, E; Fernandez-Ramos, A; Vazquez, S A

    2005-06-23

    Large-scale classical trajectory calculations have been performed to study the reaction Ar + CH4--> CH3 +H + Ar in the temperature range 2500 energy surface used for ArCH4 is the sum of the nonbonding pairwise potentials of Hase and collaborators (J. Chem. Phys. 2001, 114, 535) that models the intermolecular interaction and the CH4 intramolecular potential of Duchovic et al. (J. Phys. Chem. 1984, 88, 1339), which has been modified to account for the H-H repulsion at small bending angles. The thermal rate coefficient has been calculated, and the zero-point energy (ZPE) of the CH3 product molecule has been taken into account in the analysis of the results; also, two approaches have been applied for discarding predissociative trajectories. In both cases, good agreement is observed between the experimental and trajectory results after imposing the ZPE of CH3. The energy-transfer parameters have also been obtained from trajectory calculations and compared with available values estimated from experiment using the master equation formalism; in general, the agreement is good.

  18. Effects of laser radiation parameters of the infrared multiphoton dissociation of protonated trichloroethylene

    International Nuclear Information System (INIS)

    Ungureanu, C.; Almasan, V.

    1994-01-01

    The favorable properties of the infrared multiphoton absorption and dissociation of trichloroethylene-H, (C 2 HCl 3 ), by TEA-CO 2 laser radiation and rapid isotopic exchange between this molecule and water, indicate that it can be a promising further candidate for the final enrichment of heavy water (> 98% D 2 O), by laser method. We present the results obtained in the isotopic selectivity of multiphoton absorption measurements and in the study of the pulse energy and frequency laser radiation influence on the infrared multiphoton dissociation of C 2 HCl 3 in isotopic mixture with C 2 DCl 3 . (Author)

  19. Effect of disorder on exciton dissociation in conjugated polymers

    International Nuclear Information System (INIS)

    Feng Yuwen; Zhao Hui; Chen Yuguang; Yan Yonghong

    2017-01-01

    By using a multi-configurational time-dependent Hartree–Fock (MCTDHF) method for the time-dependent Schrödinger equation and a Newtonian equation of motion for lattice, we investigate the disorder effects on the dissociation process of excitons in conjugated polymer chains. The simulations are performed within the framework of an extended version of the Su–Schrieffer–Heeger model modified to include on-site disorder, off-diagonal, electron–electron interaction, and an external electric field. Our results show that Coulomb correlation effects play an important role in determining the exciton dissociation process. The electric field required to dissociate an exciton can practically impossibly occur in a pure polymer chain, especially in the case of triplet exciton. However, when the on-site disorder effects are taken into account, this leads to a reduction in mean dissociation electric fields. As the disorder strength increases, the dissociation field decreases effectively. On the contrary, the effects of off-diagonal disorder are negative in most cases. Moreover, the dependence of exciton dissociation on the conjugated length is also discussed. (paper)

  20. Vibrational relaxation and dissociation of D2(vj) on Cu(111)

    International Nuclear Information System (INIS)

    Cacciatore, M.; DeFelice, P.; Capitelli, M.

    1992-01-01

    The dissociative chemisorption of H 2 /D 2 with single crystal Cu surface has recently been the object of experimental and theoretical investigations. Here the authors present their results for the D 2 (vj)/Cu(111) system obtained within a semiclassical model developed for the interaction of molecules with non-rigid surfaces. The dissociation probability for D 2 in a specific initial (vj) state has been computed as a function of the impact energy and the surface temperature set to 300K. The quantum tunneling probability through the potential barriers has also been evaluated. The results show that the D 2 dissociation probability is smaller when compared to that of H 2 . The D 2 absorption probability, as well as the energy transferred to the surface phonons, is higher then that found for H 2

  1. Three-body dissociations: The photodissociation of dimethyl sulfoxide at 193 nm

    Energy Technology Data Exchange (ETDEWEB)

    Blank, D.A.; North, S.W.; Stranges, D. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    When a molecule with two equivalent chemical bonds is excited above the threshold for dissociation of both bonds, how the rupture of the two bonds is temporally coupled becomes a salient question. Following absorption at 193 nm dimethyl sulfoxide (CH{sub 3}SOCH{sub 3}) contains enough energy to rupture both C-S bonds. This can happen in a stepwise (reaction 1) or concerted (reaction 2) fashion where the authors use rotation of the SOCH{sub 3} intermediate prior to dissociation to define a stepwise dissociation: (1) CH{sub 3}SOCH{sub 3} {r_arrow} 2CH{sub 3} + SO; (2a) CH{sub 3}SOCH{sub 3} {r_arrow} CH{sub 3} + SOCH{sub 3}; and (2b) SOCH{sub 3} {r_arrow} SO + CH{sub 3}. Recently, the dissociation of dimethyl sulfoxide following absorption at 193 nm was suggested to involve simultaneous cleavage of both C-S bonds on an excited electronic surface. This conclusion was inferred from laser induced fluorescence (LIF) and resonant multiphoton ionization (2+1 REMPI) measurements of the internal energy content in the CH{sub 3} and SO photoproducts and a near unity quantum yield measured for SO. Since this type of concerted three body dissociation is very interesting and a rather rare event in photodissociation dynamics, the authors chose to investigate this system using the technique of photofragment translational spectroscopy at beamline 9.0.2.1. The soft photoionization provided by the VUV undulator radiation allowed the authors to probe the SOCH{sub 3} intermediate which had not been previously observed and provided good evidence that the dissociation of dimethyl sulfoxide primarily proceeds via a two step dissociation, reaction 2.

  2. Three-body dissociations: The photodissociation of dimethyl sulfoxide at 193 nm

    International Nuclear Information System (INIS)

    Blank, D.A.; North, S.W.; Stranges, D.

    1997-01-01

    When a molecule with two equivalent chemical bonds is excited above the threshold for dissociation of both bonds, how the rupture of the two bonds is temporally coupled becomes a salient question. Following absorption at 193 nm dimethyl sulfoxide (CH 3 SOCH 3 ) contains enough energy to rupture both C-S bonds. This can happen in a stepwise (reaction 1) or concerted (reaction 2) fashion where the authors use rotation of the SOCH 3 intermediate prior to dissociation to define a stepwise dissociation: (1) CH 3 SOCH 3 → 2CH 3 + SO; (2a) CH 3 SOCH 3 → CH 3 + SOCH 3 ; and (2b) SOCH 3 → SO + CH 3 . Recently, the dissociation of dimethyl sulfoxide following absorption at 193 nm was suggested to involve simultaneous cleavage of both C-S bonds on an excited electronic surface. This conclusion was inferred from laser induced fluorescence (LIF) and resonant multiphoton ionization (2+1 REMPI) measurements of the internal energy content in the CH 3 and SO photoproducts and a near unity quantum yield measured for SO. Since this type of concerted three body dissociation is very interesting and a rather rare event in photodissociation dynamics, the authors chose to investigate this system using the technique of photofragment translational spectroscopy at beamline 9.0.2.1. The soft photoionization provided by the VUV undulator radiation allowed the authors to probe the SOCH 3 intermediate which had not been previously observed and provided good evidence that the dissociation of dimethyl sulfoxide primarily proceeds via a two step dissociation, reaction 2

  3. The Off-rate of Monomers Dissociating from Amyloid-β Protofibrils*

    Science.gov (United States)

    Grüning, Clara S. R.; Klinker, Stefan; Wolff, Martin; Schneider, Mario; Toksöz, Küpra; Klein, Antonia N.; Nagel-Steger, Luitgard; Willbold, Dieter; Hoyer, Wolfgang

    2013-01-01

    The interconversion of monomers, oligomers, and amyloid fibrils of the amyloid-β peptide (Aβ) has been implicated in the pathogenesis of Alzheimer disease. The determination of the kinetics of the individual association and dissociation reactions is hampered by the fact that forward and reverse reactions to/from different aggregation states occur simultaneously. Here, we report the kinetics of dissociation of Aβ monomers from protofibrils, prefibrillar high molecular weight oligomers previously shown to possess pronounced neurotoxicity. An engineered binding protein sequestering specifically monomeric Aβ was employed to follow protofibril dissociation by tryptophan fluorescence, precluding confounding effects of reverse or competing reactions. Aβ protofibril dissociation into monomers follows exponential decay kinetics with a time constant of ∼2 h at 25 °C and an activation energy of 80 kJ/mol, values typical for high affinity biomolecular interactions. This study demonstrates the high kinetic stability of Aβ protofibrils toward dissociation into monomers and supports the delineation of the Aβ folding and assembly energy landscape. PMID:24247242

  4. The Many Faces of Dissociation: Opportunities for Innovative Research in Psychiatry

    Science.gov (United States)

    2014-01-01

    It has been claimed that the progress of psychiatry has lagged behind that of other medical disciplines over the last few decades. This may suggest the need for innovative thinking and research in psychiatry, which should consider neglected areas as topics of interest in light of the potential progress which might be made in this regard. This review is concerned with one such field of psychiatry: dissociation and dissociative disorders. Dissociation is the ultimate form of human response to chronic developmental stress, because patients with dissociative disorders report the highest frequency of childhood abuse and/or neglect among all psychiatric disorders. The cardinal feature of dissociation is a disruption in one or more mental functions. Dissociative amnesia, depersonalization, derealization, identity confusion, and identity alterations are core phenomena of dissociative psychopathology which constitute a single dimension characterized by a spectrum of severity. While dissociative identity disorder (DID) is the most pervasive condition of all dissociative disorders, partial representations of this spectrum may be diagnosed as dissociative amnesia (with or without fugue), depersonalization disorder, and other specified dissociative disorders such as subthreshold DID, dissociative trance disorder, acute dissociative disorders, and identity disturbances due to exposure to oppression. In addition to constituting disorders in their own right, dissociation may accompany almost every psychiatric disorder and operate as a confounding factor in general psychiatry, including neurobiological and psycho-pharmacological research. While an anti- dissociative drug does not yet exist, appropriate psychotherapy leads to considerable improvement for many patients with dissociative disorders. PMID:25598819

  5. The dissociation of vibrationally excited CH3OSO radicals and their photolytic precursor, methoxysulfinyl chloride.

    Science.gov (United States)

    Alligood, Bridget W; Womack, Caroline C; Straus, Daniel B; Blase, Frances R; Butler, Laurie J

    2011-05-21

    The dissociation dynamics of methoxysulfinyl radicals generated from the photodissociation of CH(3)OS(O)Cl at 248 nm is investigated using both a crossed laser-molecular beam scattering apparatus and a velocity map imaging apparatus. There is evidence of only a single photodissociation channel of the precursor: S-Cl fission to produce Cl atoms and CH(3)OSO radicals. Some of the vibrationally excited CH(3)OSO radicals undergo subsequent dissociation to CH(3) + SO(2). The velocities of the detected CH(3) and SO(2) products show that the dissociation occurs via a transition state having a substantial barrier beyond the endoergicity; appropriately, the distribution of velocities imparted to these momentum-matched products is fit by a broad recoil kinetic energy distribution extending out to 24 kcal/mol in translational energy. Using 200 eV electron bombardment detection, we also detect the CH(3)OSO radicals that have too little internal energy to dissociate. These radicals are observed both at the parent CH(3)OSO(+) ion as well as at the CH(3)(+) and SO(2)(+) daughter ions; they are distinguished by virtue of the velocity imparted in the original photolytic step. The detected velocities of the stable radicals are roughly consistent with the calculated barriers (both at the CCSD(T) and G3B3 levels of theory) for the dissociation of CH(3)OSO to CH(3) + SO(2) when we account for the partitioning of internal energy between rotation and vibration as the CH(3)OSOCl precursor dissociates. © 2011 American Institute of Physics.

  6. Photophysical properties of neutral and dissociated forms of rosmarinic acid

    Energy Technology Data Exchange (ETDEWEB)

    Danaf, Nader Al [Department of Chemistry, American University of Beirut, Beirut (Lebanon); Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen (Germany); Melhem, Racha Abi [Department of Chemistry, American University of Beirut, Beirut (Lebanon); Assaf, Khaleel I.; Nau, Werner M. [Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen (Germany); Patra, Digambara, E-mail: dp03@aub.edu.lb [Department of Chemistry, American University of Beirut, Beirut (Lebanon)

    2016-07-15

    Polyphenols are bioactive components that have attracted attention by chemists over many years. Rosmarinic acid (RA) is a polyphenol that is widely investigated for its broad range of potential applications as an anti-carcinogenic agent, an anti-inflammatory drug, and antioxidant. The spectroscopic properties of this molecule are addressed in details in this study. The absorption and fluorescence of RA are investigated at different pH values, characterizing the dissociated forms of RA. In a similar manner, RA was characterized in a set of different solvents. The spectral shifts of RA in the different solvents were addressed by using the Lippert–Mataga and the Stokes' shift vs. E{sub T}30 plots, which revealed two sets of linearity for the behavior of RA in polar protic and aprotic solvents. The lifetime decay profile of the dissociated forms of RA and those of RA in different solvents are characterized by bi-exponential lifetime decay functions. A theoretical study on the molecular structure of the different dissociated forms of RA is also reported. The simulated UV–vis spectra of the dissociated forms of RA were studied and compared to the experimental spectra by performing TDDFT calculations. Besides the UV-simulated spectra, the frontier molecular orbitals (FMO) of the different RA dissociated forms were also calculated.

  7. Photophysical properties of neutral and dissociated forms of rosmarinic acid

    International Nuclear Information System (INIS)

    Danaf, Nader Al; Melhem, Racha Abi; Assaf, Khaleel I.; Nau, Werner M.; Patra, Digambara

    2016-01-01

    Polyphenols are bioactive components that have attracted attention by chemists over many years. Rosmarinic acid (RA) is a polyphenol that is widely investigated for its broad range of potential applications as an anti-carcinogenic agent, an anti-inflammatory drug, and antioxidant. The spectroscopic properties of this molecule are addressed in details in this study. The absorption and fluorescence of RA are investigated at different pH values, characterizing the dissociated forms of RA. In a similar manner, RA was characterized in a set of different solvents. The spectral shifts of RA in the different solvents were addressed by using the Lippert–Mataga and the Stokes' shift vs. E T 30 plots, which revealed two sets of linearity for the behavior of RA in polar protic and aprotic solvents. The lifetime decay profile of the dissociated forms of RA and those of RA in different solvents are characterized by bi-exponential lifetime decay functions. A theoretical study on the molecular structure of the different dissociated forms of RA is also reported. The simulated UV–vis spectra of the dissociated forms of RA were studied and compared to the experimental spectra by performing TDDFT calculations. Besides the UV-simulated spectra, the frontier molecular orbitals (FMO) of the different RA dissociated forms were also calculated.

  8. Attosecond control of dissociative ionization of O{sub 2} molecules

    Energy Technology Data Exchange (ETDEWEB)

    Siu, W.; Kelkensberg, F.; Gademann, G. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Rouzee, A.; Vrakking, M. J. J. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Max-Born-Institut, Max-Born Strasse 2A, D-12489 Berlin (Germany); Johnsson, P. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Department of Physics, Lund University, Post Office Box 118, SE-221 00 Lund (Sweden); Dowek, D. [Laboratoire des Collisions Atomiques et Moleculaires (UMR Universite Paris-Sud et CNRS, 8625), Batiment 351, Universite Paris-Sud, F-91405 Orsay Cedex (France); Lucchini, M.; Calegari, F. [Department of Physics, Politecnico di Milano, Istituto di Fotonica e Nanotecnologie CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); De Giovannini, U.; Rubio, A. [Nano-bio Spectroscopy Group, ETSF Scientific Development Centre, Universidad del Pais Vasco, Avenida Tolosa 72, E-20018 San Sebastian (Spain); Lucchese, R. R. [Department of Chemistry, Texas A and M University, Post Office Box 30012, College Station, Texas 77842-3012 (United States); Kono, H. [Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Lepine, F. [Universite Lyon 1/CNRS/LASIM, UMR 5579, 43 Boulevard Du 11 Novembre 1918, F-69622 Villeurbane (France)

    2011-12-15

    We demonstrate that dissociative ionization of O{sub 2} can be controlled by the relative delay between an attosecond pulse train (APT) and a copropagating infrared (IR) field. Our experiments reveal a dependence of both the branching ratios between a range of electronic states and the fragment angular distributions on the extreme ultraviolet (XUV) to IR time delay. The observations go beyond adiabatic propagation of dissociative wave packets on IR-induced quasistatic potential energy curves and are understood in terms of an IR-induced coupling between electronic states in the molecular ion.

  9. Subtypes of dissociative (conversion) disorder in two tertiary hospitals in Bangladesh.

    Science.gov (United States)

    Ahsan, M S; Mullick, S I; Sobhan, M A; Khanam, M; Nahar, J S; Salam, M A; Ali, R; Islam, M; Kabir, M S

    2010-01-01

    Dissociative (conversion) disorders are common among the patients attending in and out patients of Psychiatry Department of tertiary hospitals in Bangladesh. This study was done to see the subtypes of dissociative (conversion) disorder according to International Classification of Diseases, Tenth Revision (ICD-10). This is a descriptive, cross sectional study done on 100 consecutive patients from the Departments of Psychiatry, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka and Dhaka Medical College Hospital (DMCH). Study period was July 2005 to June 2006. Among the patients of dissociative (conversion) disorder, mixed dissociative (conversion) disorder was found highest 34%, followed by dissociative convulsion 33%, dissociative motor disorders 19%, dissociative anaesthesia and sensory loss 5%, dissociative amnesia 4%, dissociative fugue 3%. However, the researcher did not find any multiple personality disorder which is relatively common in North America. This finding reflected that there are differences in prevalence of sub types of dissociative disorders in Bangladesh and Western countries.

  10. Dissociation of metastable CH3CO radicals studied by time-resolved photofragment imaging

    Science.gov (United States)

    Suzuki, Toshinori; Shibata, Takeshi; Li, Haiyang

    1998-05-01

    A novel experimental technique to measure the energy- dependent unimolecular dissociation rate k(E) of radical species is presented. Internally excited CH3CO radicals were formed by ultraviolet photodissociation of CH3COCl, and the subsequent decay of these radicals was detected by subpicosecond time-clocked photofragment imaging. The CH3CO radicals with different internal energies were dispersed in space by their recoil velocities, and their decay rates were measured for each internal energy.

  11. Modelling of infrared multiphoton absorption and dissociation for design of reactors for isotope separation by lasers

    International Nuclear Information System (INIS)

    Takeuchi, Kazuo; Nakane, Ryohei; Inoue, Cihiro

    1981-01-01

    A series of experiments were performed on infrared laser beam absorption (multiphoton absorption) and subsequent dissociation (multiphoton dissociation) of CF 3 Cl to propose models for the design of reactors for isotope separation by lasers. A parallel beam geometry was utilized in batch irradiation experiments to make direct compilation of lumped-parameter data possible. Multiphoton absorption is found to be expressed by a power-law extension of the law of Lambert and by an addition of a new term for buffer gas effect to the law of Beer. For reaction analysis, a method to evaluate the effect of incomplete mixing on apparent reaction rates is first presented. Secondly, multiphoton dissociation of Cf 3 Cl is found to occur in pseudo-first order fashion and the specific reaction rates for different beam fluence are shown to be correlated to the absorbed energy. (author)

  12. An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses

    Directory of Open Access Journals (Sweden)

    Sarah Jane Hobbs

    2016-06-01

    Full Text Available Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%. In these speed-matched trials, mean centre of pressure (COP cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P = .001 from being more caudally located in hind-first dissociation (mean location = 0.41 ± 0.04 through synchronous (0.36 ± 0.02 to a more cranial location in fore-first dissociation (0.32 ± 0.02. Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation

  13. Model, First-Principle Calculation of Ammonia Dissociation on Si(100 Surface. Importance of Proton Tunneling

    Directory of Open Access Journals (Sweden)

    Marek Z. Zgierski

    2003-06-01

    Full Text Available Abstract: The dissociation of an ammonia molecule on a cluster of Si atoms simulating the 100 silicon crystal structure with two Si dimers has been investigated by means of the DFT and an approximate instanton methods. The model corresponds to the low coverage limit of the surface. Absolute rate constants of two different dissociation paths are evaluated together with deuterium isotope effects. It is demonstrated that, even at room temperatures, the process is dominated by tunneling and that dissociation to a silicon atom of the adjacent dimer, rather than a silicon within the same dimer, is the prevailing mechanism. This leads to creation of a metastable structure which will slowly decay through a two-step hydrogen atom migration towards the absolute minimum on the potential energy surface corresponding to the NH2 group and the hydrogen atom residing in the same dimer.

  14. An outpatient clinical study of dissociative disorder not otherwise specified.

    Science.gov (United States)

    Yanartaş, Ömer; Özmen, Hülya Akar; Citak, Serhat; Zincir, Selma Bozkurt; Sünbül, Esra Aydin

    2014-05-01

    The relatively high prevalence of the diagnosis of dissociative disorder not otherwise specified is frequently considered to be disproportionate. The disproportionate rate of this diagnosis is thought to be related to nosologic and/or diagnostic issues in dissociative identity disorder. We sought to investigate and compare the symptom patterns of these two clinical entities. We conducted a cross-sectional study involving 1314 participants who were screened with the Dissociative Experience Scale (DES) and the Somatoform Dissociation Questionnaire (SDQ). Of the participants, 272 who scored above the cut-off points for the screening questionnaires (DES score>30 and/or SDQ score>40 points) were invited to complete a structured interview using the Dissociative Disorders Interview Schedule (DDIS); of this subsample, only 190 participants agreed to participate in the second phase of the study. The mean score for the DES was 18.55±17.23, and the mean score for the SDQ was 30.19±13.32. Of the 190 participants, 167 patients were diagnosed as having a dissociative disorder (87.8%). We found that DD-NOS was the most prevalent category of dissociative disorder. There was a significantly larger percentage of patients in the DID group than in the DD-NOS group according to secondary features of DID and Schneiderian symptoms. The secondary features of DID and Schneiderian symptoms appeared to be more specific for DID, while no differences were detected between DID and DD-NOS based on most of the items on the SCL 90R. Further longitudinal studies are needed to determine the features that are similar and dissimilar between DD-NOS and DID. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Ionization and dissociation dynamics of vinyl bromide probed by femtosecond extreme ultraviolet transient absorption spectroscopy

    International Nuclear Information System (INIS)

    Lin, Ming-Fu; Neumark, Daniel M.; Gessner, Oliver; Leone, Stephen R.

    2014-01-01

    Strong-field induced ionization and dissociation dynamics of vinyl bromide, CH 2 =CHBr, are probed using femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy. Strong-field ionization is initiated with an intense femtosecond, near infrared (NIR, 775 nm) laser field. Femtosecond XUV pulses covering the photon energy range of 50-72 eV probe the subsequent dynamics by measuring the time-dependent spectroscopic features associated with transitions of the Br (3d) inner-shell electrons to vacancies in molecular and atomic valence orbitals. Spectral signatures are observed for the depletion of neutral C 2 H 3 Br, the formation of C 2 H 3 Br + ions in their ground (X ~ ) and first excited (A ~ ) states, the production of C 2 H 3 Br ++ ions, and the appearance of neutral Br ( 2 P 3/2 ) atoms by dissociative ionization. The formation of free Br ( 2 P 3/2 ) atoms occurs on a timescale of 330 ± 150 fs. The ionic A ~ state exhibits a time-dependent XUV absorption energy shift of ∼0.4 eV within the time window of the atomic Br formation. The yield of Br atoms correlates with the yield of parent ions in the A ~ state as a function of NIR peak intensity. The observations suggest that a fraction of vibrationally excited C 2 H 3 Br + (A ~ ) ions undergoes intramolecular vibrational energy redistribution followed by the C–Br bond dissociation. The C 2 H 3 Br + (X ~ ) products and the majority of the C 2 H 3 Br ++ ions are relatively stable due to a deeper potential well and a high dissociation barrier, respectively. The results offer powerful new insights about orbital-specific electronic processes in high field ionization, coupled vibrational relaxation and dissociation dynamics, and the correlation of valence hole-state location and dissociation in polyatomic molecules, all probed simultaneously by ultrafast table-top XUV spectroscopy

  16. Rate coefficients for low-energy electron dissociative attachment to molecular hydrogen

    International Nuclear Information System (INIS)

    Horacek, J.; Houfek, K.; Cizek, M.; Murakami, I.; Kato, T.

    2003-02-01

    Calculation of rate constants for dissociative electron attachment to molecular hydrogen is reported. The calculation is based on an improved nonlocal resonance model of Cizek, Horacek and Domcke which takes fully into account the nonlocality of the resonance dynamics and uses potentials with correct asymptotic forms. The rate constants are calculated for all quantum numbers v and J of the target molecules and for electron temperature in the range 0-30000 K. (author)

  17. Substrate dependence of electron-stimulated O - yields from dissociative electron attachment to physisorbed O2

    Science.gov (United States)

    Huels, M. A.; Parenteau, L.; Sanche, L.

    1994-03-01

    We present measurements of O- electron stimulated desorption yields obtained under identical experimental conditions from 0.15 monolayers (ML) of O2 deposited onto disordered substrates consisting of 4 ML of either Kr, Xe, C2H6, C2H4, N2O, CH3Cl, or H2O, all condensed on Pt (polycrystalline). The resulting O- yield functions, for incident electron energies below 20 eV, are compared to that obtained from the O2/Kr solid; this allows us to assess the order of magnitude effects of the local substrate environment on dissociative electron attachment (DEA) via the 2Πu and gas phase forbidden 2Σ+g,u resonances of O-2. We note that, in addition to electron energy losses in the substrate prior to DEA to O2 and post-dissociation interactions of the O- with the substrate molecules, charge or energy transfer from the O-2 transient anion to a substrate molecule, and capture of the incident electron into a dissociative anion resonance of the substrate molecule may contribute to a reduced O- yield from the physisorbed O2. In the case of O2 deposited on amorphous ice, we find that the O- signal from DEA to O2 is completely absent for electron energies below 14 eV; we attribute this to a complete quenching of the dissociative O-2(2Πu, 2Σ+) resonances by the adjacent water molecules.

  18. Dissociation Pathways of Benzylpyridinium "Thermometer" Ions Depend on the Activation Regime: An IRMPD Spectroscopy Study

    NARCIS (Netherlands)

    Morsa, D.; Gabelica, V.; Rosu, F.; Oomens, J.; De Pauw, E.

    2014-01-01

    The dissociation of benzylpyridinium "thermometer" ions is widely used to calibrate the internal energy of ions produced in mass spectrometry. The fragmentation mechanism is usually believed to yield a benzylium cation, although recent studies suggest the possibility of a rearrangement leading to

  19. Dissociative attachment reactions of electrons with gas phase superacids

    International Nuclear Information System (INIS)

    Liu, X.

    1992-01-01

    Using the flowing afterglow Langmuir probe (FALP) technique, dissociative attachment coefficients β for reactions of electrons with gas phase superacids HCo(PF 3 ) 4 , HRh(PF 3 ) 4 and carbonyl hydride complexes HMn(CO) 5 , HRe(CO) 5 have been determined under thermal conditions over the approximate temperature range 300∼550 K. The superacids react relatively slowly ( max ) with free electrons in a thermal plasma, and the values of β obtained this far do not show a correlation between acidity and β. The pioneer researchers in this field had speculated that any superacid would be a rapid attacher of electrons; it was found that this speculation is not true in general. The product distribution of electron attachment reaction to HCo(PF 3 ) 4 was found to be independent of temperature even though the β[HCo(PF 3 ) 4 ] increases with temperature. This proposes that the electron attachment process occurs well before the excited complex dissociates. In addition, the activation energy of HCo(PF 3 ) 4 for electron attachment has been derived from the Arrhenius plots. The carbonyl hydride complexes, HMn(CO) 5 and HRe(CO) 5 , react relatively rapidly (>1/4 of β max ) with free electrons in thermal plasma. This indicates that these reactions cannot be significantly endothermic. Observation of rapid attachment for these non-superacids shows that the Mn-CO and Re-CO bonds are weaker than the Mn-H and Re-H bonds, respectively. Comparisons between the carbonyl and trifluorophosphine cases implies that fast electron capture is related more to the CO ligand than to the transition-metal species

  20. Direct observation of characteristic dissociation behaviors of hydrate-bearing cores by rapid-scanning X-ray CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ebinuma, T.; Oyama, H.; Utiumi, T.; Nagao, J.; Narita, H. [National Inst. of Advanced Industrial Science and Technology, Toyohiraku, Sapporo (Japan)

    2008-07-01

    Methane hydrate has significant potential as a new source of energy. Major considerations in developing production methods of methane from hydrates are the fundamental properties of hydrate-bearing sediments, and the dissociation behavior of methane hydrate and the gas and water flow generated by its dissociation in sediments. Marine methane hydrates occur several hundred meters below the sea floor, in a variety of forms. The pore-space filling-type is considered to be the most suited to exploitation, as it is contained within the pore spaces of sandy sediments, and has relatively larger gas permeability compared to other forms. However, shallow sandy sediments are not usually consolidated, and methane hydrate is unstable at normal pressure and temperature. Therefore, common methods are not suitable, and new experimental methods have been developed to study the properties of hydrate-bearing sediment and its dissociation process. This paper presented the results of an experimental study involving the dissociation of artificial methane-hydrate-bearing sediments. The experiment was performed using X-ray computed tomography in order to directly observe dissociation behavior in the sediments and the gas and water flows generated by dissociation. The paper described the depressurization process and presented a schematic diagram of rapid scanning X-ray computed tomography scanner and core holder with tri-axial structure. The experimental apparatus for dissociation of methane hydrate was also illustrated. The thermal stimulation process and hot water injection process were explained. It was concluded that dissociation by depressurization demonstrated that the temperature reduction induced by depressurization depended on the phase equilibrium state of methane hydrate, and that dissociation preferentially occurred at the periphery of the core. This behavior was due to the heat flux from the outside of the core, where the heat flux controlled the dissociation rate. 10 refs

  1. The effect of carbon-chain oxygenation in the carbon-carbon dissociation.

    Science.gov (United States)

    Dos Santos, Lisandra Paulino; Baptista, Leonardo

    2018-06-01

    Currently, there is a trend of moving away from the use of fossil fuels to the use of biofuels. This modification changes the molecular structure of gasoline and diesel constituents, which should impact pollutant emissions and engine efficiency. An important property of automotive fuels is the resistance to autoignition. The goal of the present work is to evaluate thermochemical and kinetic parameters that govern the carbon-carbon bond dissociation and relate these parameters, in conjunction with molecular properties, to autoignition resistance. Three model reactions were investigated in the present work: dissociation of ethane, ethanol, and ethanal. All studies were conducted at the multiconfigurational level of theory, and the rate coefficients were evaluated from 300 to 2000 K. The comparison of dissociation energies and Arrhenius expressions indicates that autoignition resistance is related to the kinetic control of dissociation reactions and it is possible to relate the higher octane number of ethanol based fuels to the kinetics parameters of carbon-carbon bond fission. Graphical abstract Effect of the functional group in the Arrhenius parameters of the C-C dissociation. Arrhenius curves calculated at NEVPT2(6,6)/6-311G(2df,2pd).

  2. Reaction pathways of the dissociation of methylal: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Frey, H -M; Beaud, P; Gerber, T; Mischler, B; Radi, P P; Tzannis, A -P [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Schemata for modelling combustion processes do not yet include reaction rates for oxygenated fuels like methylal (DMM) which is considered as an additive or replacement for diesel due to its low sooting propensity. Density functional theory (DFT) studies of the possible reaction pathways for different dissociation steps of methylal are presented. Cleavage of a hydrogen bond to the methoxy group or the central carbon atom were simulated at the BLYP/6-311++G{sup **} level of theory. The results are compared to the experiment when dissociating and/or ionising DMM with femtosecond pulses. (author) 1 fig., 1 tab., 1 ref.

  3. Strategic use of dissociation in ethical argumentation on abortion

    Directory of Open Access Journals (Sweden)

    Simona Mazilu

    2008-01-01

    Full Text Available This paper is concerned with the dialectical and rhetorical consequences of the use of dissociation in ethical argumentation on abortion. Disputants make strategic use of dissociation to advance their standpoints, to establish the starting points of the discussion and to argue in favor or against abortion as well. From the pragma-dialectical perspective (van Rees 2002, 2003, 2005a, 2005b, 2006, dissociation is defined as an argumentative technique by which a unitary concept is divided into two different concepts of which one is intended as positive while the other one as negative. The analysis of a religious text on abortion shows that by means of dissociation abortion can be conceived of as “an unspeakable crime” or “the deliberate killing of an innocent human being” as opposed to “interruption of pregnancy”, the term preferred by pro-choice supporters. I claim that the protagonist uses dissociation as a rhetorical strategy aimed at persuading both the interlocutor and the audience.

  4. Transient photoelectron spectroscopy of the dissociative Br2(1Piu) state.

    Science.gov (United States)

    Strasser, Daniel; Goulay, Fabien; Leone, Stephen R

    2007-11-14

    Photodissociation of bromine on the Br2(1Piu) state is probed with ultrafast extreme ultraviolet (53.7 nm) single-photon ionization. Time-resolved photoelectron spectra show simultaneously the depletion of ground state bromine molecules as well as the rise of Br(2P3/2) products due to 402.5 nm photolysis. A partial photoionization cross-section ratio of atomic versus molecular bromine is obtained. Transient photoelectron spectra of a dissociative wave packet on the excited state are presented in the limit of low-power-density, single-photon excitation to the dissociative state. Transient binding energy shifts of "atomic-like" photoelectron peaks are observed and interpreted as photoionization of nearly separated Br atom pairs on the Br2(1Piu) state to repulsive dissociative ionization states.

  5. Heterolytic dissociative adsorption state of dihydrogen favored by interfacial defects

    Science.gov (United States)

    Song, Zhenjun; Hu, Hanshi; Xu, Hu; Li, Yong; Cheng, Peng; Zhao, Bin

    2018-03-01

    The atomic-scale insight into dihydrogen on MgO(001) surface deposited on molybdenum substrate with interfacial defects was investigated in detail by employing density functional methods Here we report novel dissociative adsorption behaviors of single hydrogen molecule on the usually inert oxide surfaces, with consideration of two types of dissociation schemes. The heterolytic dissociation state -Mg(H)-O(H)- of dihydrogen is impossible to obtain on neighboring O-Mg sites of perfect bulk MgO(001) terraces. Unusually, the hydrogen molecule can form heterolytic fragmentation states on metal supported MgO(001) films with very low activation barrier (0.398 eV), and the heterolytic dissociation state is much more favorable than homolytic dissociation state both energetically and kinetically in all cases. Electronic properties and bonding attribution of adsorbates and the oxide-metal hybrid structure are revealed by analyzing density of states, differential charge densities, orbital interaction and electron localization function. The characteristic changes to the property and activity of magnesia (001) can have potential application in catalytic reactions.

  6. THERMODYNAMICS OF ETHANOLAMMONIUM CATIONES DISSOCIATION IN AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    R. E. Khoma

    2017-03-01

    Full Text Available The literature data on the thermodynamics of ethanolamines onium cations dissociation have been systematized and generalized. The correlation between these cations dissociation thermodynamic functions (DH and DS and physicochemical properties (Tmp., Tbp, Pp, lgPow et al. has been revealed. There was a correlation between lipophilicity determined experimentally and calculated by QSAR. For monoethanolammonium, diethanolammonium, and their N-methyl and N-ethyl derivatives it was found dissociation thermodynamic functions to depend on bases lgPow. Acid-base dissociation of TRIS and triethanolamine onium cations does not correspond to said relationship because TRIS (primary amine, TEA (tertiary amine act differently on aqueous solutions of SO2. TEA, unlike MEA, DEA and MMEA, has a salting out effect towards sulfur dioxide because of competing hydration that promotes sulfite «onium» salts hydrolysis. TRIS promotes S(IV → S(VI sulphooxidation, in contrast to another ethanolamines. Enthalpy–enthropy compensation with isothermodynamic temperature 303 K has been recorded. The revealed correlations may be useful in developing of procedures for air sanitary cleaning from acidic gases; chemisorbents immobilized for gas and ion exchange chromatography; potentiometric methods for fluorocomplex acids determinations. The use of monoethanolamine is most promising to obtain chemisorbents because the thermodynamic functions of its onium cation acid-base dissociation are least dependent on temperature compared to other etanolammonium cations.

  7. Anomalous maximum and minimum for the dissociation of a geminate pair in energetically disordered media

    Science.gov (United States)

    Govatski, J. A.; da Luz, M. G. E.; Koehler, M.

    2015-01-01

    We study the geminated pair dissociation probability φ as function of applied electric field and temperature in energetically disordered nD media. Regardless nD, for certain parameters regions φ versus the disorder degree (σ) displays anomalous minimum (maximum) at low (moderate) fields. This behavior is compatible with a transport energy which reaches a maximum and then decreases to negative values as σ increases. Our results explain the temperature dependence of the persistent photoconductivity in C60 single crystals going through order-disorder transitions. They also indicate how an energetic disorder spatial variation may contribute to higher exciton dissociation in multicomponent donor/acceptor systems.

  8. Dissociative properties of 1,1,1,2-tetrafluoroethane obtained by computational chemistry

    Science.gov (United States)

    Hayashi, Toshio; Ishikawa, Kenji; Sekine, Makoto; Hori, Masaru

    2018-06-01

    The electronic properties and dissociative channels of the alternative to the CCl2F2 (CFC-12) refrigerant, 1,1,1,2-tetrafluoroethane (HFC-134a) with a low global warming potential (GWP, 1430), were revealed by computational chemistry. The results show that CF3 + and CHF2 + ions are mainly produced by ionization. The CF3CH2 + ion is produced by ion pair formation and by direct ionization in the energy region higher than approximately 15 eV, but also in small amounts by the ionization of the dissociated CF3CH2 radical. This information is useful for etching process engineers in leading-edge semiconductor manufacturing.

  9. Dissociative Excitation of Acetylene Induced by Electron Impact: Excitation-emission Cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Országh, Juraj; Danko, Marián; Čechvala, Peter; Matejčík, Štefan, E-mail: matejcik@fmph.uniba.sk [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina F-2, 842 48 Bratislava (Slovakia)

    2017-05-20

    The optical emission spectrum of acetylene excited by monoenergetic electrons was studied in the range of 190–660 nm. The dissociative excitation and dissociative ionization associated with excitation of the ions initiated by electron impact were dominant processes contributing to the spectrum. The spectrum was dominated by the atomic lines (hydrogen Balmer series, carbon) and molecular bands (CH(A–X), CH(B–X), CH{sup +}(B–A), and C{sub 2}). Besides the discrete transitions, we have detected the continuum emission radiation of ethynyl radical C{sub 2}H(A–X). For most important lines and bands of the spectrum we have measured absolute excitation-emission cross sections and determined the energy thresholds of the particular dissociative channels.

  10. Multidimensional Potential Energy Surface for H2 Dissociation over Cu(111)

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Scheffler, Matthias; Jacobsen, Karsten Wedel

    1994-01-01

    We present ab initio density functional calculations within the generalized gradient approximation for H-2 dissociating over Cu(111). The minimum barrier for dissociation is 0.5 eV and shows large corrugation within the unit cell and a strong dependence on the molecular orientation. Dissociation...

  11. The return of dissociation as absence within absence.

    Science.gov (United States)

    Gurevich, Hayuta

    2014-12-01

    My aim is to translate Ferenczi's central concepts of the intrapsychic impact and imprint of early developmental trauma into both revived and contemporary conceptualizations. The concept of dissociation was renounced by Freud, yet it is returning as a cornerstone of recent trauma theories. Ferenczi used the concept of "repression," but used it in the sense of an intrapsychic imprint of early external trauma that fragments consciousness, that is, as dissociation. Furthermore, early trauma is double: an absence of protection that threatens existence of the self, combined with an absence of attachment and of recognition of this threat and terror; thus it is an absence-within-absence. This contemporary conceptualization entails a widening of the intrapsychic realm to include an intersubjective one, and regards dissociation as a unique and complex intrapsychic absence, which is a negative of the external absence-within-absence in the early environment.

  12. The Dissociative Subtype of Posttraumatic Stress Disorder (PTSD) Among Adolescents: Co-Occurring PTSD, Depersonalization/Derealization, and Other Dissociation Symptoms.

    Science.gov (United States)

    Choi, Kristen R; Seng, Julia S; Briggs, Ernestine C; Munro-Kramer, Michelle L; Graham-Bermann, Sandra A; Lee, Robert C; Ford, Julian D

    2017-12-01

    The purpose of this study was to examine the co-occurrence of posttraumatic stress disorder (PTSD) and dissociation in a clinical sample of trauma-exposed adolescents by evaluating evidence for the depersonalization/derealization dissociative subtype of PTSD as defined by the DSM-5 and then examining a broader set of dissociation symptoms. A sample of treatment-seeking, trauma-exposed adolescents 12 to 16 years old (N = 3,081) from the National Child Traumatic Stress Network Core Data Set was used to meet the study objectives. Two models of PTSD/dissociation co-occurrence were estimated using latent class analysis, one with 2 dissociation symptoms and the other with 10 dissociation symptoms. After model selection, groups within each model were compared on demographics, trauma characteristics, and psychopathology. Model A, the depersonalization/derealization model, had 5 classes: dissociative subtype/high PTSD; high PTSD; anxious arousal; dysphoric arousal; and a low symptom/reference class. Model B, the expanded dissociation model, identified an additional class characterized by dissociative amnesia and detached arousal. These 2 models provide new information about the specific ways PTSD and dissociation co-occur and illuminate some differences between adult and adolescent trauma symptom expression. A dissociative subtype of PTSD can be distinguished from PTSD alone in adolescents, but assessing a wider range of dissociative symptoms is needed to fully characterize adolescent traumatic stress responses. Copyright © 2017 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

  13. Investigating the thermal dissociation of viral capsid by lattice model

    Science.gov (United States)

    Chen, Jingzhi; Chevreuil, Maelenn; Combet, Sophie; Lansac, Yves; Tresset, Guillaume

    2017-11-01

    The dissociation of icosahedral viral capsids was investigated by a homogeneous and a heterogeneous lattice model. In thermal dissociation experiments with cowpea chlorotic mottle virus and probed by small-angle neutron scattering, we observed a slight shrinkage of viral capsids, which can be related to the strengthening of the hydrophobic interaction between subunits at increasing temperature. By considering the temperature dependence of hydrophobic interaction in the homogeneous lattice model, we were able to give a better estimate of the effective charge. In the heterogeneous lattice model, two sets of lattice sites represented different capsid subunits with asymmetric interaction strengths. In that case, the dissociation of capsids was found to shift from a sharp one-step transition to a gradual two-step transition by weakening the hydrophobic interaction between AB and CC subunits. We anticipate that such lattice models will shed further light on the statistical mechanics underlying virus assembly and disassembly.

  14. Dissociation From a Cross-Cultural Perspective: Implications of Studies in Brazil.

    Science.gov (United States)

    Maraldi, Everton de Oliveira; Krippner, Stanley; Barros, Maria Cristina Monteiro; Cunha, Alexandre

    2017-07-01

    A major issue in the study of dissociation concerns the cross-cultural validity of definitions and measurements used to identify and classify dissociative disorders. There is also extensive debate on the etiological factors underlying dissociative experiences. Cross-cultural research is essential to elucidate these issues, particularly regarding evidence obtained from countries in which the study of dissociation is still in its infancy. The aim of this article was to discuss Brazilian research on the topic of dissociation, highlighting its contributions for the understanding of dissociative experiences in nonclinical populations and for the validity and relevance of dissociative disorders in the contexts of psychiatry, psychology, and psychotherapy. We also consider the ways in which dissociative experiences are assimilated by Brazilian culture and religious expressions, and the implications of Brazilian studies for the sociocultural investigation of dissociation. We conclude by addressing the limitations of these studies and potential areas for future research.

  15. Traumatic dissociation as a predictor of posttraumatic stress disorder in South African female rape survivors.

    Science.gov (United States)

    Nöthling, Jani; Lammers, Kees; Martin, Lindi; Seedat, Soraya

    2015-04-01

    Women survivors of rape are at an increased risk for posttraumatic stress disorder (PTSD). Traumatic dissociation has been identified as a precursor of PTSD. This study assessed the predictive potential of traumatic dissociation in PTSD and depression development.The study followed a longitudinal, prospective design. Ninety-seven female rape survivors were recruited from 2 clinics in Cape Town, South Africa. Clinical interviews and symptom status assessments of the participants were completed to measure dissociation, childhood traumas, resilience, depression, and PTSD.Traumatic dissociation was a significant predictor of PTSD and depression. The linear combination of prior dissociation, current dissociation, and resilience significantly explained 20.7% of the variance in PTSD. Dissociation mediated the relationship between resilience and PTSD.As traumatic dissociation significantly predicts PTSD, its early identification and management may reduce the risk of developing PTSD. Interventions focused on promoting resilience may also be successful in reducing the risk of dissociation following rape.

  16. Traumatic Dissociation as a Predictor of Posttraumatic Stress Disorder in South African Female Rape Survivors

    Science.gov (United States)

    Nöthling, Jani; Lammers, Kees; Martin, Lindi; Seedat, Soraya

    2015-01-01

    Abstract Women survivors of rape are at an increased risk for posttraumatic stress disorder (PTSD). Traumatic dissociation has been identified as a precursor of PTSD. This study assessed the predictive potential of traumatic dissociation in PTSD and depression development. The study followed a longitudinal, prospective design. Ninety-seven female rape survivors were recruited from 2 clinics in Cape Town, South Africa. Clinical interviews and symptom status assessments of the participants were completed to measure dissociation, childhood traumas, resilience, depression, and PTSD. Traumatic dissociation was a significant predictor of PTSD and depression. The linear combination of prior dissociation, current dissociation, and resilience significantly explained 20.7% of the variance in PTSD. Dissociation mediated the relationship between resilience and PTSD. As traumatic dissociation significantly predicts PTSD, its early identification and management may reduce the risk of developing PTSD. Interventions focused on promoting resilience may also be successful in reducing the risk of dissociation following rape. PMID:25906104

  17. Correlations between channel probabilities in collisional dissociation of D3+

    International Nuclear Information System (INIS)

    Abraham, S.; Nir, D.; Rosner, B.

    1984-01-01

    Measurements of the dissociation of D 3 + ions at 300--600 keV under single- and multiple-collision conditions in Ar- and H 2 -gas targets have been performed. A complete separation of all dissociation channels was achieved, including the neutral channels, which were resolved using a fine-mesh technique. Data analysis in the multiple-collision regime confirms the validity of the rate equations governing the charge exchange processes. In the single-collision region the analysis yields constant relations between channel probabilities. Data rearrangement shows probability factorization and suggests that collisional dissociation is a two-stage process, a fast electron exchange followed by rearrangement and branching to the exit channels

  18. Optical observations of molecular dissociation in thin foils

    International Nuclear Information System (INIS)

    Berry, H.G.; Gay, T.J.; Brooks, R.L.

    1981-01-01

    We have measured the intensity and polarizations of light emitted from atomic excited states of dissociated molecular ions. Using HeH + projectiles, we have observed factors of 1-5 enhancements of the light from n=3, sup(1,3)P,D states of He I and some He II and H I emissions. Observations of Lyman alpha emission after dissociation of H 2 + and H 3 + show rapid variations in light yield for small internuclear separations at the foil surface. (author)

  19. Thermogravimetric analysis and dissociation pressure of caesium trihalides

    International Nuclear Information System (INIS)

    Harris, G.S.; McKechnie, J.S.

    1982-01-01

    We have carried out a thermogravimetric study of caesium trihalides to obtain, from the procedural decomposition temperatures, an order of apparent thermal stability which could be compared with the order of thermodynamic stability obtained from vapour pressure measurements. Thermogravimetric analysis could also prove to be a useful method for rapid analysis of metal polyhalides. The thermograms indicated a one-step decomposition for each compound; the procedural decomposition temperatures and percentage weight losses obtained are given. Dissociation pressures were measured and values of equilibrium constant and enthalpy of dissociation were calculated. The results are given. The 'stability' order obtained is discussed. (U.K.)

  20. Electron-neutral scattering cross sections for CO2: a complete and consistent set and an assessment of dissociation

    International Nuclear Information System (INIS)

    Grofulović, Marija; Alves, Luís L; Guerra, Vasco

    2016-01-01

    This work proposes a complete and consistent set of cross sections for electron collisions with carbon dioxide (CO 2 ) molecules to be published in the IST-Lisbon database with LXCat. The set is validated from the comparison between swarm parameters calculated using a two-term Boltzmann solver and the available experimental data. The importance of superelastic collisions with CO 2 (0 1 0) molecules at low values of the reduced electric field is discussed. Due to significant uncertainties, there are ongoing debates regarding the deconvolution of cross sections that describe generic energy losses at specific energy thresholds into cross sections that describe individual processes. An important example of these uncertainties is with the dissociation of CO 2 , for which the total electron impact dissociation cross section has not yet been unambiguously identified. The available dissociation cross sections are evaluated and discussed, and a strategy to obtain electron-impact dissociation rate coefficients is suggested. (paper)

  1. Excited neutral atomic fragments in the strong-field dissociation of N2 molecules

    International Nuclear Information System (INIS)

    Nubbemeyer, T; Eichmann, U; Sandner, W

    2009-01-01

    Excited neutral N* fragments with energies between 3 eV and 15 eV have been observed from the dissociation of N 2 molecules in strong laser fields. The kinetic energy spectrum of the excited neutral atoms corresponds to Coulomb explosion processes involving N + ions. This supports the assumption that the production of excited neutral fragments stems from a process in which one of the participating ions in the Coulomb explosion captures an electron into a Rydberg state.

  2. Decisive role of nuclear quantum effects on surface mediated water dissociation at finite temperature

    Science.gov (United States)

    Litman, Yair; Donadio, Davide; Ceriotti, Michele; Rossi, Mariana

    2018-03-01

    Water molecules adsorbed on inorganic substrates play an important role in several technological applications. In the presence of light atoms in adsorbates, nuclear quantum effects (NQEs) influence the structural stability and the dynamical properties of these systems. In this work, we explore the impact of NQEs on the dissociation of water wires on stepped Pt(221) surfaces. By performing ab initio molecular dynamics simulations with van der Waals corrected density functional theory, we note that several competing minima for both intact and dissociated structures are accessible at finite temperatures, making it important to assess whether harmonic estimates of the quantum free energy are sufficient to determine the relative stability of the different states. We thus perform ab initio path integral molecular dynamics (PIMD) in order to calculate these contributions taking into account the conformational entropy and anharmonicities at finite temperatures. We propose that when adsorption is weak and NQEs on the substrate are negligible, PIMD simulations can be performed through a simple partition of the system, resulting in considerable computational savings. We then calculate the full contribution of NQEs to the free energies, including also anharmonic terms. We find that they result in an increase of up to 20% of the quantum contribution to the dissociation free energy compared with the harmonic estimates. We also find that the dissociation process has a negligible contribution from tunneling but is dominated by zero point energies, which can enhance the rate of dissociation by three orders of magnitude. Finally we highlight how both temperature and NQEs indirectly impact dipoles and the redistribution of electron density, causing work function changes of up to 0.4 eV with respect to static estimates. This quantitative determination of the change in the work function provides a possible approach to determine experimentally the most stable configurations of water

  3. Visible luminescence studies in the infrared multiphoton dissociation of 1,2-dichloro-1,1-difluoroethane

    Science.gov (United States)

    Pushpa, K. K.; Kumar, Awadesh; Naik, P. D.; Annaji Rao, K.; Parthasarathy, V.; Sarkar, S. K.; Mittal, J. P.

    1997-11-01

    A strong visible luminescence was observed in the CO 2 laser induced infrared multiphoton dissociation of 1,2-dichloro-1,1-difluoroethane. The emission observed between 350-750 nm is attributed to electronically excited carbene CF 2ClCH. The temporal profile of this luminescence was studied as a function of laser pulse duration, pulse energy, excitation frequency and substrate pressure. A suitable dissociation mechanism is presented considering various channels of IRMPD of this molecule.

  4. Diagnostic challenges leading to underdiagnosis of dissociative disorders

    Directory of Open Access Journals (Sweden)

    Aadil M

    2017-02-01

    Full Text Available Muhammad Aadil,1 Maria Shoaib2 1Department of Psychiatry, Rush University Medical Center, Chicago, IL, USA; 2Department of medicine, Dow Medical College, Karachi, PakistanWe read the article “Is the Dissociative Experiences Scale able to identify detachment and compartmentalization symptoms? Factor structure of the Dissociative Experiences Scale in a large sample of psychiatric and nonpsychiatric subjects” by Mazzotti et al with great interest and would like to add our views in its support.1View the original paper by Mazzotti and colleagues.

  5. UV dissociation of vibrationally excited UF6

    International Nuclear Information System (INIS)

    Alexandre, M.; Clerc, M.; Gagnon, R.; Gilbert, M.; Isnard, P.; Nectoux, P.; Rigny, P.; Weulersse, J.M.

    1983-01-01

    Before application of laser photodissociation of UF 6 to the separation of uranium isotopes becomes practical, isotopic selectivity should be optimized. We present here results on the cross sections involved in the irradiation of UF 6 simultaneously with infrared and ultraviolet lasers, as a function of wavelengths, fluence and temperature (at 293 K and 105 K, in an adiabatic expansion). The experiment uses a Nd 3+ YAG pumped lithium niobate optical parametric oscillator as a tunable 16 μ light source. Energies of the order of 1 mJ can be obtained with linewidths smaller than 0.1 cm - . The UV source used is based on ND 3+ YAG pumped dye laser and various frequency mixing schemes. At low temperature the frequency variation of the absorbed infrared energy per molecule depends markedly on the IR fluence phisub(IR) with a maximum value varying as phisub(IR)sup(-1/2) and a frequency extension far beyond the low level absorption spectrum. The absorbed vibrational energy leads to a change in the UV cross section comparable with the effect of a rise in temperature. Using this a model is put forward to express the isotopic selectivity 235 U/ 238 U as a function of UV wavelength and IR irradiation conditions. Experimental results agree with this model, and yield to maximum selectivity close to two [fr

  6. Formation and dissociation of dust molecules in dusty plasma

    International Nuclear Information System (INIS)

    Yan Jia; Feng Fan; Liu Fucheng; Dong Lifang; He Yafeng

    2016-01-01

    Dust molecules are observed in a dusty plasma experiment. By using measurements with high spatial resolution, the formation and dissociation of the dust molecules are studied. The ion cloud in the wake of an upper dust grain attracts the lower dust grain nearby. When the interparticle distance between the upper dust grain and the lower one is less than a critical value, the two dust grains would form a dust molecule. The upper dust grain always leads the lower one as they travel. When the interparticle distance between them is larger than the critical value, the dust molecule would dissociate. (paper)

  7. Dissociation and ionization of molecular ions by ultra-short intense laser pulses probed by coincidence 3D momentum imaging

    International Nuclear Information System (INIS)

    Ben-Itzhak, Itzik; Wang, Pengqian; Xia, Jiangfan; Max Sayler, A.; Smith, Mark A.; Maseberg, J.W.; Carnes, Kevin D.; Esry, Brett D.

    2005-01-01

    We have experimentally explored laser-induced dissociation and ionization of diatomic molecular ions using coincidence 3D momentum imaging. The vibrationally excited molecular ion beam (4-8 keV) is crossed by an ultrafast intense laser beam (28-200 fs, 10 13 -10 14 W/cm 2 ). The resulting fragments are recorded in coincidence by a time and position-sensitive detector. Complete angular distributions and kinetic energy release maps are reconstructed from the measured dissociation-momentum vectors. The angular distribution of the H + + H fragments was found to be strongly correlated to their kinetic energy release upon dissociation. Low KER was associated with very narrow angular distributions and high KER with distributions peaking away from the laser polarization. Ionization was found to be smaller than dissociation and increased with laser intensity. The H + + H + fragments have a very narrow angular distribution along the laser polarization

  8. Dissociation behavior of Np(IV) from humic acid colloid

    Energy Technology Data Exchange (ETDEWEB)

    Iijima, K.; Tobitsuka, S. [Japan Nuclear Cycle Development Institute, 4-33 Muramatsu, Tokai, Naka-gun, Ibaraki 319-1194 (Japan); Kohara, Y. [Inspection Development Corporation, 4-33, Muramatsu, Tokai, Nakagun, Ibaraki 319-1112 (Japan)

    2005-07-01

    Full text of publication follows: Dissociation behavior of Np(IV) from humic colloid, which was prepared with purified Aldrich humic acid (PAHA) was investigated. The complexation experiments were carried out in 0.1 M NaClO{sub 4} - 0.05 M Na{sub 2}S{sub 2}O{sub 4} solution at pH 8 with PAHA concentration between 0 and 500 mg L-1 under anaerobic condition. Np-237 was added as Np(V) solution so that its concentration becomes 1.1 x 10-5 mol L-1. After shaking from 1 to 156 days, aliquots of experimental solution were filtered through the membranes with 50, 10 and 3 kD of MWCO to obtain the size distribution of colloid, followed by adding the filtrate into the 6 M HCl for dissociation. At the end of experiments for 596 days, 0.1 M NaHCO{sub 3} was used for dissociation solution. The concentration of Np released into this solution was evaluated by measuring a activity of Np-237. The concentration of Np becomes constant by 112 days. Since Eh of the solution has been kept between -300 and -100 mV vs. SHE during experimental duration, Np is presumed to be reduced into tetravalent. In the case of higher PAHA concentration than 50 mg L{sup -1}, the Np concentration is close to that of initially added Np. Since the size of the dissolved species of Np during complexation experiments varies from 3 to 50 kD, the Np is sorbed on humic acid colloid. In the dissociation experiments, the Np dissociated by 6 M HCl decreases with increasing complexation time and PAHA concentration. After 156 days complexation with 500 mg L{sup -1} of PAHA, 35% of Np can be dissociated from the colloid. Such a tendency, however, is not observed in case of the lowest PAHA concentration, 5 mg L{sup -1}. After 596 days complexation, the dissociation experiments were carried out by adding 0.1 M NaHCO{sub 3} solution to avoid the precipitation which might hinder the dissociation of Np in the aforementioned experiments with HCl. As a result, 50% of Np is dissociated in the presence of 50 and 100 mg L-1 of

  9. A review of the dissociative disorders: from multiple personality disorder to the posttraumatic stress

    Directory of Open Access Journals (Sweden)

    Modesto J. Romero-López

    Full Text Available In this paper we review the idea of dissociation, dissociative disorders and their relationship with the processes of consciousness. We will deal specifically with multiple personality disorder and posttraumatic stress disorder. Both polarize the discussion of diagnostic categories with dissociative symptoms. This review compares the initial ideas (one century old with the current scenario and emerging trends in research, which are relating cognitive processes and dissociative phenomena and disorders from a neuroscientific approach. We discuss the ideas on dissociation, hypnosis and suicide associated with these disorders. There seems to be a lack of consensus as to the nature of dissociation with theoretical, empirical and clinical implications.

  10. Dissociation: adjustment or distress? Dissociative phenomena, absorption and quality of life among Israeli women who practice channeling compared to women with similar traumatic history.

    Science.gov (United States)

    Stolovy, Tali; Lev-Wiesel, Rachel; Witztum, Eliezer

    2015-06-01

    This study aimed to explore the relationship between traumatic history, dissociative phenomena, absorption and quality of life among a population of channelers, in comparison with a population of non-channelers with similar traumatic history. The study sample included 150 women. The measures included Traumatic Experiences Scale, Dissociative Experience Scale, Absorption Scale, Brief Symptom Inventory and Quality of Life (QOL) Assessment. Channelers presented significantly higher levels of dissociation, absorption and psychological health compared to the other group. Dissociation and absorption were trauma-related only among the comparison group. Hence, dissociation has different qualities among different people, and spiritual practice contributes to QOL.

  11. Low-energy electron-induced dissociation in condensed-phase L-cysteine II: a comparative study on anion desorption from chemisorbed and physisorbed films

    International Nuclear Information System (INIS)

    Alizadeh, E.; Rowntree, P.A.; Massey, S.; Sanche, L.

    2016-01-01

    In recent years it has become apparent that dissociative attachment of low energy electrons (DEA) is important for the description of radiation damage to biologically relevant molecules and living cells. Due to its multifunctional structure, cysteine is becoming an ideal model molecule for investigating the complex interactions of proteins with metallic surfaces such as gold nanoparticles. We report herein the results of low-energy electron induced degradation of L-cysteine films, chemisorbed on a gold substrate via the thiol group or physisorbed into a clean gold surface. The data were recorded under ultra-high vacuum conditions at room temperature. Anion yields desorbed from these films by the impact of 0.5 to 19 eV electrons provide clear evidence of the efficient decomposition of this amino acid via dissociative electron attachment (i.e., from dissociation of intermediate transient anions located between 5 and 14 eV). The peaks in the desorbed-anion yield functions, associated with DEA, are superimposed on a continuously rising signal attributed to dipolar dissociation. Similar to the results previously observed from physisorbed films, light anionic species, with masses lower than 35 amu, have been detected. In addition, we measured for first time fragments at 14 amu (CH_2"-) and 15 amu (CH_3"-) desorbing from physisorbed films, as well as heavier fragments of mass 45 and 46 amu desorbing from chemisorbed films

  12. The rates measurement of methane hydrate formation and dissociation using micro-drilling system application for gas hydrate exploration

    Energy Technology Data Exchange (ETDEWEB)

    Bin Dou [Engineering Faculty, China Univ. of Geosciences, Wuhan (China)]|[Inst. of Petroleum Engineering, Technology Univ. of Clausthal (Germany); Reinicke, K.M. [Inst. of Petroleum Engineering, Technology Univ. of Clausthal (Germany); Guosheng Jiang; Xiang Wu; Fulong Ning [Engineering Faculty, China Univ. of Geosciences, Wuhan (China)

    2006-07-01

    When drilling through gas hydrate bearing formations, the energy supplied by virtue of the drilling process may lead to a destabilization of the hydrates surrounding the wellbore. Therefore, as the number of oil and gas fields being development in deepwater and onshore arctic environments increases, greater emphasis should be placed on quantifying the risks, gas hydrates pose to drilling operations. The qualification of these risks requires a comprehensive understanding of gas hydrate-formation and dissociation as a result of drilling induced processes. To develop the required understanding of gas hydrat formation and dissociation, the authors conducted laboratory experiments by using a micro-drilling system, to study the dissociation rates of methane hydrates contained in a tank reactor. The test facility used is a development of China University of Geosciences. The rates of methane hydrate formation and dissociation in the tank reactor were measured at steady-state conditions at pressures ranging from 0.1 to 25 MPa and temperatures ranging from -5 to 20 C. The experimental results show that the rate of hydrate formation is strongly influenced by the fluid system used to form the hydrates, pressure and temperature, with the influence of the temperature on methane hydrate dissociation being stronger than that of the pressure. Drilling speed, drilling fluids and hydrate dissociation inhibitors were also shown to influence hydrate dissociation rate. The derived results have been used to predict hydrate drilling stability for several drilling fluid systems.

  13. Dissociation of 1P states in hot QCD Medium Using Quasi-Particle Model

    Science.gov (United States)

    Nilima, Indrani; Agotiya, Vineet Kumar

    2018-03-01

    We extend the analysis of a very recent work [1] to study the dissociation phenomenon of 1P states of the charmonium and bottomonium spectra (χc and χb) in a hot QCD medium using Quasi-Particle Model. This study employed a medium modified heavy quark potential which has quite different form in the sense that it has a lomg range Coulombic tail in addition to the Yukawa term even above the deconfinement temperature. Then we study the flavor dependence of their binding energies and explore the nature of dissociation temperatures by employing the Quasi-Particle debye mass for pure gluonic and full QCD case. Interestingly, the dissociation temperatures obtained by employing EoS1 and EoS2 with the Γ criterion, is closer to the upper bound of the dissociation temperatures which are obtained by the dissolution of a given quarkonia state by the mean thermal energy of the quasi-partons in the hot QCD/QGP medium.

  14. Out of mind - out of sight : studies on clinical and psychophysiological characteristics of dissociative identity disorder

    OpenAIRE

    Dale, Karl Yngvar

    2008-01-01

    Dissociative identity disorder (DID; APA, 1994), previously labeled Multiple personality (APA, 1980) and Multiple Personality Disorder (APA, 1987), has good diagnostic validity (Gleaves, May, & Cardeña, 2001) and is supported by taxometric research, whereby two types of dissociation have been identified: Pathological dissociation, whose features are consistent with DID, and nonpathological dissociation (Waller, Putnam, & Carlson, 1996). On these grounds, we aimed to contribute to a further...

  15. Dissociation, Paranormal Belief, and Quality of Life in Older People

    Directory of Open Access Journals (Sweden)

    Tungshan Chou

    2015-12-01

    Full Text Available The measurement of religiosity in current health-related literature is mostly based on the traditional Christian belief system. It has been argued that such a measurement approach may misrepresent the true degree of religiosity in Taiwanese people. In this study, religiosity was measured in two ways: self-reported religion type and a qualitatively derived index of religious piety based on principles as suggested by Gries, Su, and Schak to be used in the Taiwanese context. Their effects on dissociation, paranormal belief, and quality of life were juxtaposed for comparison. In addition, the beneficial effect of religious piety was examined in the framework of McClenon’s ritual healing theory. A total of 266 healthy older adults across Taiwan were interviewed by four trained assistants over a 4-month period. Factor scores were used to represent the dissociative tendencies (depersonalization/derealization, forgetfulness, amnesia, and psychological absorption and paranormal belief facets (precognition, psi power, other forms of life, traditional religious belief, superstition, and telepathy. The results showed that older people of high religious piety display better quality of life profiles than their counterparts in the low religious piety group. The effects of self-reported religion type were mainly seen with paranormal beliefs compatible with their religious beliefs, whereas the effects of religious piety were more pronounced in relation to quality of life than dissociation and paranormal belief. The beneficial advantage of dissociation hypothesized by ritual healing theory did not receive empirical support in the nonclinical sample of this study.

  16. Assessment of dissociation in Bosnian treatment-seeking refugees in Denmark.

    Science.gov (United States)

    Palic, Sabina; Carlsson, Jessica; Armour, Cherie; Elklit, Ask

    2015-05-01

    Dissociative experiences are common in traumatized individuals, and can sometimes be mistaken for psychosis. It is difficult to identify pathological dissociation in the treatment of traumatized refugees, because there is a lack of systematic clinical descriptions of dissociative phenomena in refugees. Furthermore, we are currently unaware of how dissociation measures perform in this clinical group. To describe the phenomenology of dissociative symptoms in Bosnian treatment-seeking refugees in Denmark. As a part of a larger study, dissociation was assessed systematically in 86 Bosnian treatment-seeking refugees using a semi-structured clinical interview (Structured Interview for Disorders of Extreme Stress-dissociation subscale; SIDES-D) and a self-report scale (Dissociative Experiences Scale; DES). The SIDES-D indicated twice as high prevalence of pathological dissociation as the DES. According to the DES, 30% of the refugees had pathological dissociation 15 years after their resettlement. On the SIDES-D, depersonalization and derealization experiences were the most common. Also, questions about depersonalization and derealization at times elicited reporting of visual and perceptual hallucinations, which were unrelated to traumatic re-experiencing. Questions about personality alteration elicited spontaneous reports of a phenomenon of "split" pre- and post-war identity in the refugee group. Whether this in fact is a dissociative phenomenon, characteristic of severe traumatization in adulthood, needs further examination. Knowledge of dissociative symptoms in traumatized refugees is important in clinical settings to prevent misclassification and to better target psychotherapeutic interventions. Much development in the measurement of dissociation in refugees is needed.

  17. The adsorption and dissociation of water molecule on goethite (010) surface: A DFT approach

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Long, E-mail: shuweixia@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Xiu, Fangyuan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Qiu, Meng [Qingdao Institute of Bioenergy and Bioprocess Technology (China); Xia, Shuwei; Yu, Liangmin [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China)

    2017-01-15

    Graphical abstract: The optimized structure of hydrated goethite (010) surface with medium water coverage (water density about 6.7 H{sub 2}O/nm{sup 2}). - Highlights: • Stable adsorption and dissociation structure of H{sub 2}O on goethite (010) surface was investigated by DFT. • Reasonable path for water dissociation was proposed by transitional state analysis. • The mechanism of water adsorption on goethite and binding nature were revealed by PDOS. - Abstract: Using density functional theory (DFT) calculation, we investigate the configuration, stability and electronic properties of fresh cleaved (010) goethite surface (Pnma) and this surface exposed to water monolayer at low, medium and high coverage. Water is predicted to be chemisorbed to the surface, together with the surface reconstruction. The interaction energy of the most stable configuration of both low and medium coverage per water molecule is almost the same (−1.17 eV), while that of high coverage is much lower (less than 1.03 eV). It indicates that highly hydrated surface is less stable. PDOS analysis reveals the adsorption of H{sub 2}O is due to the formation of Fe−O bond, caused by overlapping of Fe's 3d and O's 2p orbitals. Dissociation processes at low and medium water coverage are non-spontaneous; while at high coverage, it can undertake spontaneously both thermodynamically and dynamically. The dissociation paths of all three water coverage are the similar. The proton from one adsorbed water is likely to dissociate to bind to the vicinal surface μ{sub 3}−O as an intermediate product; the proton belonged to μ{sub 3}−O transferred to the neighbor surface μ{sub 2}−O as the dissociative configuration.

  18. Perception, action, and Roelofs effect: a mere illusion of dissociation.

    Directory of Open Access Journals (Sweden)

    Paul Dassonville

    2004-11-01

    Full Text Available A prominent and influential hypothesis of vision suggests the existence of two separate visual systems within the brain, one creating our perception of the world and another guiding our actions within it. The induced Roelofs effect has been described as providing strong evidence for this perception/action dissociation: When a small visual target is surrounded by a large frame positioned so that the frame's center is offset from the observer's midline, the perceived location of the target is shifted in the direction opposite the frame's offset. In spite of this perceptual mislocalization, however, the observer can accurately guide movements to the target location. Thus, perception is prone to the illusion while actions seem immune. Here we demonstrate that the Roelofs illusion is caused by a frame-induced transient distortion of the observer's apparent midline. We further demonstrate that actions guided to targets within this same distorted egocentric reference frame are fully expected to be accurate, since the errors of target localization will exactly cancel the errors of motor guidance. These findings provide a mechanistic explanation for the various perceptual and motor effects of the induced Roelofs illusion without requiring the existence of separate neural systems for perception and action. Given this, the behavioral dissociation that accompanies the Roelofs effect cannot be considered evidence of a dissociation of perception and action. This indicates a general need to re-evaluate the broad class of evidence purported to support this hypothesized dissociation.

  19. Post-mortem CT evaluation of atlanto-occipital dissociation.

    Science.gov (United States)

    Madadin, Mohammed; Samaranayake, Ravindra Priyalal; O'Donnell, Chris; Cordner, Stephen

    2017-02-01

    Atlanto-occipital dissociation injury is an important injury in forensic pathology practice. Radiological diagnosis of atlanto-occipital dissociation clinically is assessed by direct measurement of occipito-vertebral skeletal relationships. Different measurements may be used to diagnose atlanto-occipital dissociation, including the basion-dens interval (BDI) and basion-axial interval (BAI). It is not known whether the normal ante-mortem measurements of BDI and BAI described in the literature are applicable to post-mortem CT images of the occipito-cervical junction (OCJ) or whether these measurements could be affected by early post-mortem changes. This study aims to compare post-mortem BDI and BAI measurements with ante-mortem values. Post-mortem CT scans of the cervical spines of 100 deceased adults were reviewed, and the BDI and BAI were measured. Different parameters were recorded in each case. The results from this study suggest that there are no effects of post-mortem changes on the measurement of BAI as relied upon clinically. There appear to be some effects of fully established rigor mortis on BDI measurement, shortening it. This may have consequences for the post mortem diagnosis of atlanto-occipital dissociation. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  20. Cross-sections for dissociative excitation of lead atom in collisions of slow electrons with PbI2 molecules

    International Nuclear Information System (INIS)

    Smirnov, Yu.M.

    2006-01-01

    The dissociative excitation of the lead atom in e-PbI 2 collisions has been studied experimentally. 27 excitation cross-sections are measured at an exciting-electron energy of 100 eV. Nine optical excitation functions are recorded at the electron energy varying in the 0-100 eV range. The most possible reaction channels at low electron energies along with the relation of the dissociative-excitation cross-sections of the lead atom both in e-PbI 2 and e-PbCl 2 collisions are discussed. (authors)

  1. Correlation diagram approach to the dissociative ionization mechanisms of methanol

    International Nuclear Information System (INIS)

    Momigny, J.; Wankenne, H.; Krier, C.

    1980-01-01

    A systematic survey is made of the dissociation processes from the ground state and from the electronically excited states of CH 3 OH + . Most metastable processes occurring in the mass spectrum of CD 3 OH are studied also, including measurement of the kinetic energy release and appearance potentials. It is shown that if ionic species such as CH 2 OH + , CH 2 O + and HCO + are present in the mass spectrum of CH 3 OH, the isomers CH 3 O + , HCOH + and COH + are also present. The precursors of these ions having been identified by the metastable processes, correlation diagrams are used to show that, from the first ionization potential of CH 3 OH to 14 eV, the only exception being CH 3 O + which results from an electronically spin-forbidden predissociation, the fragment ions can be considered to result from adiabatic decay of the ground state of CH 3 OH + . The potential barriers involved in these adiabatic processes result either from conical intersection or from avoided-crossing between the ground state of CH 3 OH + and the electronically excited states occurring up to 14 eV. At higher energies, many non-adiabatic processes occur; for example, the appearance of CD 2 O + and the electronically excited states of HCO + and COH + ions. It is shown additionally that kinetic energy releases observed in the collision-induced processes CH 3 OH + → CH 2 OH + + H and CH 2 OH + → HCO + + H 2 are in good agreement with the mechanistic approach via the correlation diagram for the appearance of the non-collision-induced ion processes. (orig.)

  2. Dissociative recombination of rare gas hydride ions: II. ArH+

    International Nuclear Information System (INIS)

    Mitchell, J B A; Novotny, O; LeGarrec, J L; Florescu-Mitchell, A; Rebrion-Rowe, C; Stolyarov, A V; Child, M S; Svendsen, A; Ghazaly, M A El; Andersen, L H

    2005-01-01

    A storage ring measurement of the rate coefficient for the production of neutral Ar in e + ArH + collisions is described. It is found that the recombination rate is too small to measure at low centre-of-mass energies but the combined rate coefficient for dissociative recombination and dissociative excitation increases above 2.5 eV displaying peaks centred at 7.5 eV, 16 and 26 eV. Calculated potential energy curves for the ground and excited states of ArH + are presented and these aid in the elucidation of the recombination and excitation processes observed at higher energies. The implications for plasma modelling are discussed. (letter to the editor)

  3. Clinical Assessment of Dissociative Identity Disorder among College Counseling Clients

    Science.gov (United States)

    Levy, Benjamin; Swanson, Janine E.

    2008-01-01

    College counseling professionals address a wide range of complex student mental health concerns. Among these, accurately identifying client presentations of dissociative identity disorder (DID) can be especially challenging because students with DID sometimes present as if they are experiencing another problem, such as a mood, anxiety, or…

  4. Self Blocking of CO Dissociation on a Stepped Ruthenium Surface

    DEFF Research Database (Denmark)

    Vendelbo, Søren Bastholm; Johansson, Martin; Mowbray, Duncan

    2010-01-01

    The influence of steps on CO reactions has been studied on a Ru(0 1 (1) over bar 5 4) single crystal with a step density of 4%. Based on temperature programmed desorption (TPD) and oxygen titration experiments as well as density functional theory (DFT) calculations, we show that the CO dissociation...

  5. A Validation Study of the Adolescent Dissociative Experiences Scale

    Science.gov (United States)

    Keck Seeley, Susan. M.; Perosa, Sandra, L.; Perosa, Linda, M.

    2004-01-01

    Objective: The purpose of this study was to further the validation process of the Adolescent Dissociative Experiences Scale (A-DES). In this study, a 6-item Likert response format with descriptors was used when responding to the A-DES rather than the 11-item response format used in the original A-DES. Method: The internal reliability and construct…

  6. Infrared Multiple Photon Dissociation Spectroscopy Of Metal Cluster-Adducts

    Science.gov (United States)

    Cox, D. M.; Kaldor, A.; Zakin, M. R.

    1987-01-01

    Recent development of the laser vaporization technique combined with mass-selective detection has made possible new studies of the fundamental chemical and physical properties of unsupported transition metal clusters as a function of the number of constituent atoms. A variety of experimental techniques have been developed in our laboratory to measure ionization threshold energies, magnetic moments, and gas phase reactivity of clusters. However, studies have so far been unable to determine the cluster structure or the chemical state of chemisorbed species on gas phase clusters. The application of infrared multiple photon dissociation IRMPD to obtain the IR absorption properties of metal cluster-adsorbate species in a molecular beam is described here. Specifically using a high power, pulsed CO2 laser as the infrared source, the IRMPD spectrum for methanol chemisorbed on small iron clusters is measured as a function of the number of both iron atoms and methanols in the complex for different methanol isotopes. Both the feasibility and potential utility of IRMPD for characterizing metal cluster-adsorbate interactions are demonstrated. The method is generally applicable to any cluster or cluster-adsorbate system dependent only upon the availability of appropriate high power infrared sources.

  7. Experimental investigation of gas heating and dissociation in a microwave plasma torch at atmospheric pressure

    International Nuclear Information System (INIS)

    Su, Liu; Kumar, Rajneesh; Ogungbesan, Babajide; Sassi, Mohamed

    2014-01-01

    Highlights: • Atmospheric-pressure microwave plasma torch. • Gas heating and dissociation. • Parametric studies of plasma operating conditions. • Local thermal equilibrium plasma. - Abstract: Experimental investigations are made to understand gas heating and dissociation in a microwave (MW) plasma torch at atmospheric pressure. The MW induced plasma torch operates at 2.45 GHz frequency and up to 2 kW power. Three different gas mixtures are injected in the form of axial flow and swirl flow in a quartz tube plasma torch to experimentally investigate the MW plasma to gas energy transfer. Air–argon, air–air and air–nitrogen plasmas are formed and their operational ranges are determined in terms of gas flow rates and MW power. Visual observations, optical emission spectroscopy and K-type thermocouple measurements are used to characterize the plasma. The study reveals that the plasma structure is highly dependent on the carrier gas type, gas flow rate, and MW power. However, the plasma gas temperature is shown not to vary much with these parameters. Further spectral and analytical analysis show that the plasma is in thermal equilibrium and presents very good energy coupling between the microwave power and gas heating and dissociation. The MW plasma torch outlet temperature is also measured and found to be suitable for many thermal heating and chemical dissociation applications

  8. Control of concerted two bond versus single bond dissociation in CH3Co(CO)4 via an intermediate state using pump-dump laser pulses

    Science.gov (United States)

    Ambrosek, David; González, Leticia

    2007-10-01

    Wavepacket propagations on ab initio multiconfigurational two-dimensional potential energy surfaces for CH3Co(CO)4 indicate that after irradiation to the lowest first and second electronic excited states, concerted dissociation of CH3 and the axial CO ligand takes place. We employ a pump-dump sequence of pulses with appropriate frequencies and time delays to achieve the selective breakage of a single bond by controlling the dissociation angle. The pump and dump pulse sequence exploits the unbound surface where dissociation occurs in a counterintuitive fashion; stretching of one bond in an intermediate state enhances the single dissociation of the other bond.

  9. Control of concerted two bond versus single bond dissociation in CH(3)Co(CO)(4) via an intermediate state using pump-dump laser pulses.

    Science.gov (United States)

    Ambrosek, David; González, Leticia

    2007-10-07

    Wavepacket propagations on ab initio multiconfigurational two-dimensional potential energy surfaces for CH(3)Co(CO)(4) indicate that after irradiation to the lowest first and second electronic excited states, concerted dissociation of CH(3) and the axial CO ligand takes place. We employ a pump-dump sequence of pulses with appropriate frequencies and time delays to achieve the selective breakage of a single bond by controlling the dissociation angle. The pump and dump pulse sequence exploits the unbound surface where dissociation occurs in a counterintuitive fashion; stretching of one bond in an intermediate state enhances the single dissociation of the other bond.

  10. Kinematic study of O--ion formation from dissociative electron attachment to SO2

    Science.gov (United States)

    Jana, Irina; Nandi, Dhananjay

    2018-04-01

    We report a complete kinematic study of O--ion formation due to dissociative electron attachment to SO2 using the velocity slice imaging technique in the incident electron energy range over the resonances. Two resonances are observed at 5.2 and 7.5 eV, respectively. From the kinetic energy distribution, the two resonances are observed to have the same threshold energy, pointing to the fact that the two processes, giving rise to the two resonant peaks, have the same dissociation limit. From the angular distribution results we identified the involvement of an A1 and a combination of A1+B2 temporary negative-ion state(s) for the first and second resonances, respectively.

  11. Assessing the Dissociability of Recollection and Familiarity in Recognition Memory

    Science.gov (United States)

    Pratte, Michael S.; Rouder, Jeffrey N.

    2012-01-01

    Recognition memory is often modeled as constituting 2 separate processes, recollection and familiarity, rather than as constituting a single process mediated by a generic latent strength. One way of stating evidence for the more complex 2-process model is to show dissociations with select manipulations, in which one manipulation affects…

  12. Dissociative ionization of O2 and N2 by electron impact

    International Nuclear Information System (INIS)

    Deleanu, L.; Stockdale, J.A.

    1975-05-01

    A crossed molecular-pulsed electron beam apparatus used for the study of dissociative ionization of molecules by electron impact is described. The kinetic energy spectra of O + , N + and N ++ ions formed from dissociation of O 2 and N 2 by impact of threshold to 300 eV electrons measured by a time-of-flight method are presented. The ion energy spectra were obtained as a function of incident electron energy at a fixed electron beam-ion detector angle and at a fixed electron energy for electron beam-ion detector angles between 30 and 110 0 . Four main groups of O + ions were observed peaking at 0.8, 2.0, 3.0, and 5.0 eV kinetic energy. Angular distributions of all four of these groups are essentially isotropic. Four distinct groups of N + ions were observed in the N + kinetic energy spectra peaking at 1.9 eV, 2.2 to 2.5 eV, 3 to 4 eV and 6 to 7.6 eV. The angular distributions for N + ions of various kinetic energies were substantially isotropic. An attempt was made to measure the excitation function of N + from N 2 but the results were not very satisfactory. Nevertheless the excitation function data were analyzed by plotting the N + kinetic energy versus the value of the electron energy at which the abrupt changes in the slope of the excitation functions (''breaks'') occurred. The data on kinetic energy, angular distribution and excitation function of the ionic fragments were used in an attempt to identify the molecular ion states involved in the dissociation process. The kinetic energy spectra of N ++ /N 2 showed at least four major peaks and the total N ++ angular distributions was isotropic. (U.S.)

  13. Electromagnetic Dissociation of Target Nuclei by $^{208}$Pb Projectiles

    CERN Multimedia

    Petridis, A; Wohn, F K

    2002-01-01

    % NA53 \\\\ \\\\ The purpose of this experiment is to study the process of electromagnetic dissociation (ED) that occurs at impact parameters large enough so that there is no nuclear interaction. In these cases strong electromagnetic fields are produced for a short time at the nucleus. For large charges and ultrarelativistic energies, the intense electromagnetic pulse produces cross-sections much larger than the total hadronic cross-section. These effects place significant constraints on the storage times of the heavy ion beams planned for RHIC and LHC.\\\\ \\\\In this experiment we measure the cross-sections for the one- and two-neutron removal processes resulting from the interaction of 160 and 40~GeV/nucleon Pb beams on Au and Co targets. Thin Au targets were bombarded in the beam line of the NA50 experiment. Gamma rays from the residual nuclides produced in the bombardment were measured to determine the saturation activities of $^{196}$Au and $^{195}$Au resulting from ED of the Au target. This along with cross-se...

  14. Theoretical resonant electron-impact vibrational excitation, dissociative recombination and dissociative excitation cross sections of ro-vibrationally excited BeH"+ ion

    International Nuclear Information System (INIS)

    Laporta, V.; Chakrabarti, K.; Celiberto, R.; Janev, R. K.; Mezei, J. Zs.; Niyonzima, S.; Tennyson, J.; Schneider, I.F.

    2017-01-01

    A theoretical study of resonant vibrational excitation, dissociative recombination and dissociative excitation processes of the beryllium monohydride cation, BeH"+ , induced by electron impact, is reported. Full sets of ro-vibrationally-resolved cross sections and of the corresponding Maxwellian rate coefficients are presented for the three processes. Particular emphasis is given to the high-energy behaviour. Potential curves of "2σ"+, "2σ and "2δ symmetries and the corresponding resonance widths, obtained from R-matrix calculations, provide the input for calculations which use a local complex-potential model for resonant collisions in each of the three symmetries. Rotational motion of nuclei and isotopic effects are also discussed. The relevant results are compared with those obtained using a multichannel quantum defect theory method. Full results are available from the Phys4Entry database.

  15. Density function theory study of the adsorption and dissociation of carbon monoxide on tungsten nanoparticles.

    Science.gov (United States)

    Weng, Meng-Hsiung; Ju, Shin-Pon; Chen, Hsin-Tsung; Chen, Hui-Lung; Lu, Jian-Ming; Lin, Ken-Huang; Lin, Jenn-Sen; Hsieh, Jin-Yuan; Yang, Hsi-Wen

    2013-02-01

    The adsorption and dissociation properties of carbon monoxide (CO) molecule on tungsten W(n) (n = 10-15) nanoparticles have been investigated by density-functional theory (DFT) calculations. The lowest-energy structures for W(n) (n = 10-15) nanoparticles are found by the basin-hopping method and big-bang method with the modified tight-binding many-body potential. We calculated the corresponding adsorption energies, C-O bond lengths and dissociation barriers for adsorption of CO on nanoparticles. The electronic properties of CO on nanoparticles are studied by the analysis of density of state and charge density. The characteristic of CO on W(n) nanoparticles are also compared with that of W bulk.

  16. Assessing the structure and meaningfulness of the dissociative subtype of PTSD.

    Science.gov (United States)

    Ross, Jana; Baník, Gabriel; Dědová, Mária; Mikulášková, Gabriela; Armour, Cherie

    2018-01-01

    Studies conducted in the USA, Canada and Denmark have supported the existence of the dissociative PTSD subtype, characterized primarily by symptoms of depersonalization and derealization. The current study aimed to examine the dissociative PTSD subtype in an Eastern European, predominantly female (83.16%) sample, using an extended set of dissociative symptoms. A latent profile analysis was applied to the PTSD and dissociation data from 689 trauma-exposed university students from Slovakia. Four latent profiles of varying PTSD and dissociation symptomatology were uncovered. They were named non-symptomatic, moderate PTSD, high PTSD and dissociative PTSD. The dissociative PTSD profile showed elevations on depersonalization and derealization, but also the alternative dissociative indicators of gaps in awareness and memory, sensory misperceptions and cognitive and behavioural re-experiencing. The core PTSD symptoms of 'memory impairment' and 'reckless or self-destructive behaviour' were also significantly elevated in the dissociative PTSD profile. Moreover, anxiety and anger predicted membership in the dissociative PTSD profile. The results provide support for the proposal that the dissociative PTSD subtype can be characterized by a variety of dissociative symptoms.

  17. Volume of discrete brain structures in complex dissociative disorders : preliminary findings

    NARCIS (Netherlands)

    Ehling, T.; Nijenhuis, E. R. S.; Krikke, A. P.; DeKloet, ER; Vermetten, E

    2007-01-01

    Based on findings in traumatized animals and patients with posttraumatic stress disorder, and on traumatogenic models of complex dissociative disorders, it was hypothesized that (1) patients with complex dissociative disorders have smaller volumes of hippocampus, parahippocampal gyrus, and amygdala

  18. A Strategy Combining Higher Energy C-Trap Dissociation with Neutral Loss- and Product Ion-Based MSn Acquisition for Global Profiling and Structure Annotation of Fatty Acids Conjugates.

    Science.gov (United States)

    Bi, Qi-Rui; Hou, Jin-Jun; Yang, Min; Shen, Yao; Qi, Peng; Feng, Rui-Hong; Dai, Zhuo; Yan, Bing-Peng; Wang, Jian-Wei; Shi, Xiao-Jian; Wu, Wan-Ying; Guo, De-An

    2017-03-01

    Fatty acids conjugates (FACs) are ubiquitous but found in trace amounts in the natural world. They are composed of multiple unknown substructures and side chains. Thus, FACs are difficult to be analyzed by traditional mass spectrometric methods. In this study, an integrated strategy was developed to global profiling and targeted structure annotation of FACs in complex matrix by LTQ Orbitrap. Dicarboxylic acid conjugated bufotoxins (DACBs) in Venenum bufonis (VB) were used as model compounds. The new strategy (abbreviated as HPNA) combined higher-energy C-trap dissociation (HCD) with product ion- (PI), neutral loss- (NL) based MS n (n ≥ 3) acquisition in both positive-ion mode and negative-ion mode. Several advantages are presented. First, various side chains were found under HCD in negative-ion mode, which included both known and unknown side chains. Second, DACBs with multiple side chains were simultaneously detected in one run. Compared with traditional quadrupole-based mass method, it greatly increased analysis throughput. Third, the fragment ions of side chain and steroids substructure could be obtained by PI- and NL-based MS n acquisition, respectively, which greatly increased the accuracy of the structure annotation of DACBs. In all, 78 DACBs have been discovered, of which 68 were new compounds; 25 types of substructure formulas and seven dicarboxylic acid side chains were found, especially five new side chains, including two saturated dicarboxylic acids [(azelaic acid (C 9 ) and sebacic acid (C 10 )] and three unsaturated dicarboxylic acids (u-C 8 , u-C 9 , and u-C 10 ). All these results greatly enriched the structures of DACBs in VB. Graphical Abstract ᅟ.

  19. Dissociation and diffusion of hydrogen on defect-free and vacancy defective Mg (0001) surfaces: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Han, Zongying [College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); Union Research Center of Fuel Cell, School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chen, Haipeng [College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); Zhou, Shixue, E-mail: zhoushixue66@163.com [College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266590 (China)

    2017-02-01

    Highlights: • Clarify the effect of vacancy defect on H{sub 2} dissociation on Mg (0001) surface. • Demonstrate the effects of vacancy defect on H atom diffusion. • Reveal the minimum energy diffusion path of H atom from magnesium surface into bulk. - Abstract: First-principles calculations with the density functional theory (DFT) have been carried out to study dissociation and diffusion of hydrogen on defect-free and vacancy defective Mg (0001) surfaces. Results show that energy barriers of 1.42 eV and 1.28 eV require to be overcome for H{sub 2} dissociation on defect-free and vacancy defective Mg (0001) surfaces respectively, indicating that reactivity of Mg (0001) surface is moderately increased due to vacancy defect. Besides, the existence of vacancy defect changes the preferential H atom diffusion entrance to the subsurface and reduces the diffusion energy barrier. An interesting remark is that the minimum energy diffusion path of H atom from magnesium surface into bulk is a spiral channel formed by staggered octahedral and tetrahedral interstitials. The diffusion barriers computed for H atom penetration from the surface into inner-layers are all less than 0.70 eV, which is much smaller than the activation energy for H{sub 2} dissociation on the Mg (0001) surface. This suggests that H{sub 2} dissociation is more likely than H diffusion to be rate-limiting step for magnesium hydrogenation.

  20. Molecular beam study of dissociative sticking of methane on Ni(100)

    DEFF Research Database (Denmark)

    Holmblad, Peter Mikal; Wambach, Jørg; Chorkendorff, Ib

    1995-01-01

    of the methane leads to a dramatic enhancement of the sticking, emphasizing that the initial vibrational state is of crucial importance. These results are consistent with a mechanism of direct activated dissociative chemisorption where the dynamics is dominated by a barrier in the potential energy surface mainly...... located in the vibrational coordinates. Normal-energy scaling is only approximately observed. The effect of surface temperature is also investigated but is found to be smaller than activation by translational or vibrational energy. A simplified analysis in terms of state resolved sticking curves, Snu...... American Institute of Physics....

  1. Evaluation of the Evidence for the Trauma and Fantasy Models of Dissociation

    Science.gov (United States)

    Dalenberg, Constance J.; Brand, Bethany L.; Gleaves, David H.; Dorahy, Martin J.; Loewenstein, Richard J.; Cardena, Etzel; Frewen, Paul A.; Carlson, Eve B.; Spiegel, David

    2012-01-01

    The relationship between a reported history of trauma and dissociative symptoms has been explained in 2 conflicting ways. Pathological dissociation has been conceptualized as a response to antecedent traumatic stress and/or severe psychological adversity. Others have proposed that dissociation makes individuals prone to fantasy, thereby…

  2. Emission spectroscopic studies on dynamics of molecular excitation and dissociation by controlled electron impact

    International Nuclear Information System (INIS)

    Ogawa, Teiichiro

    1986-01-01

    Emission spectrum by controlled electron impact has been a successful technique for the investigation of molecular dynamics. (1) Molecular excitation. Aromatic molecules give an optical emission similar to fluorescence. However, as is shown by the vibrational structure and the electron energy dependence of benzene emission, its excitation process is not necessarily optical. Some aliphatic molecules also exhibit an emission band at the ultraviolet region. (2) Molecular dissociation. Analysis of the Doppler profile, the threshold energy, the excitation function and the isotope effect of the atomic emission produced in electron-molecule collisions has clarified the dynamics of the molecular dissociation. Especially the Doppler profile has given the translational energy distribution of the fragment atom, which is very useful to disclose the potential energy curve. Its angular dependence has recently found to allow determination of the symmetry of the intermediate excited state and the magnetic sublevel distribution of the fragment atom. These finding has revealed detailed state-to-state dynamics of the molecular dissociation. (author)

  3. Strain effect on the adsorption, diffusion, and molecular dissociation of hydrogen on Mg (0001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Huaping; Wang, Caizhuang; Yao, Yongxin; Hupalo, Myron [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Wang, Yangang [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Supercomputing Center of Computer Network Information Center, CAS, Beijing 100190 (China); McDougall, Dan; Tringides, Michael; Ho, Kaiming [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)

    2013-12-14

    The adsorption, diffusion, and molecular dissociation of hydrogen on the biaxially strained Mg (0001) surface have been systematically investigated by the first principle calculations based on density functional theory. When the strain changes from the compressive to tensile state, the adsorption energy of H atom linearly increases while its diffusion barrier linearly decreases oppositely. The dissociation barrier of H{sub 2} molecule linearly reduces in the tensile strain region. Through the chemical bonding analysis including the charge density difference, the projected density of states and the Mulliken population, the mechanism of the strain effect on the adsorption of H atom and the dissociation of H{sub 2} molecule has been elucidated by an s-p charge transfer model. With the reduction of the orbital overlap between the surface Mg atoms upon the lattice expansion, the charge transfers from p to s states of Mg atoms, which enhances the hybridization of H s and Mg s orbitals. Therefore, the bonding interaction of H with Mg surface is strengthened and then the atomic diffusion and molecular dissociation barriers of hydrogen decrease accordingly. Our works will be helpful to understand and to estimate the influence of the lattice deformation on the performance of Mg-containing hydrogen storage materials.

  4. Dipole-Guided Electron Capture Causes Abnormal Dissociations of Phosphorylated Pentapeptides

    DEFF Research Database (Denmark)

    Moss, Christopher L.; Chung, Thomas W.; Wyer, Jean

    2011-01-01

    energies and fluoranthene anion radicals in an ion trap resulted in the loss of a hydrogen atom, ammonia, and backbone cleavages forming complete series of sequence z ions. Elimination of phosphoric acid was negligible. In contrast, capture of lowenergy electrons by doubly charged ions in a Penning ion...... mapping of the potential energy surface provided structures for the precursor phosphopeptide dications. Electron attachment produces a multitude of low lying electronic states in charge-reduced ions that determine their reactivity in backbone dissociations and H- atom loss. The predominant loss of H atoms......Abstract Electron transfer and capture mass spectra of a series of doubly charged ions that were phosphorylated pentapeptides of a tryptic type (pS,A,A,A,R) showed conspicuous differences in dissociations of charge-reduced ions. Electron transfer from both gaseous cesium atoms at 100 keV kinetic...

  5. The Dissociative Subtype of Post-traumatic Stress Disorder: Research Update on Clinical and Neurobiological Features.

    Science.gov (United States)

    van Huijstee, Jytte; Vermetten, Eric

    2017-10-21

    Recently, a dissociative subtype of post-traumatic stress disorder (PTSD) has been included in the DSM-5. This review focuses on the clinical and neurobiological features that distinguish the dissociative subtype of PTSD from non-dissociative PTSD. Clinically, the dissociative subtype of PTSD is associated with high PTSD severity, predominance of derealization and depersonalization symptoms, a more significant history of early life trauma, and higher levels of comorbid psychiatric disorders. Furthermore, PTSD patients with dissociative symptoms exhibit different psychophysiological and neural responses to the recall of traumatic memories. While individuals with non-dissociative PTSD exhibit an increased heart rate, decreased activation of prefrontal regions, and increased activation of the amygdala in response to traumatic reminders, individuals with the dissociative subtype of PTSD show an opposite pattern. It has been proposed that dissociation is a regulatory strategy to restrain extreme arousal in PTSD through hyperinhibition of limbic regions. In this research update, promises and pitfalls in current research studies on the dissociative subtype of PTSD are listed. Inclusion of the dissociative subtype of PTSD in the DSM-5 stimulates research on the prevalence, symptomatology, and neurobiology of the dissociative subtype of PTSD and poses a challenge to improve treatment outcome in PTSD patients with dissociative symptoms.

  6. Neural Dissociation of Number from Letter Recognition and Its Relationship to Parietal Numerical Processing

    Science.gov (United States)

    Park, Joonkoo; Hebrank, Andrew; Polk, Thad A.; Park, Denise C.

    2012-01-01

    The visual recognition of letters dissociates from the recognition of numbers at both the behavioral and neural level. In this article, using fMRI, we investigate whether the visual recognition of numbers dissociates from letters, thereby establishing a double dissociation. In Experiment 1, participants viewed strings of consonants and Arabic…

  7. Furfural: The Unimolecular Dissociative Photoionization Mechanism of the Simplest Furanic Aldehyde.

    Science.gov (United States)

    Winfough, Matthew; Voronova, Krisztina; Muller, Giel; Laguisma, Gabrielle; Sztáray, Bálint; Bodi, Andras; Meloni, Giovanni

    2017-05-11

    The unimolecular dissociation reactions of energy-selected furfural cations have been studied by imaging photoelectron photoion coincidence spectroscopy at the vacuum-ultraviolet (VUV) beamline of the Swiss Light Source. In the photon energy range of 10.9-14.5 eV, furfural ions decay by numerous fragmentation channels. Modeling the breakdown diagram yielded the 0 K appearance energies of 10.95 ± 0.10, 11.16, and 12.03 eV for the c-C 4 H 3 O-CO + (m/z = 95), c-C 4 H 4 O + (m/z = 68), and c-C 3 H 3 + (m/z = 39) fragment ions, respectively, formed by parallel dissociation channels. An internal conversion from the A″ to the A' electronic state via a conical intersection takes place along the reaction coordinate in the case of the H-loss channel (c-C 4 H 3 O-CO + formation). Quantum chemical calculations and experimental results confirmed a fast conversion to the A' state and that the rate-determining step is a tight transition state on the potential energy surface. Appearance energies were also derived for the sequential dissociation products from the furan cation, c-C 4 H 4 O + , for the formation of CH 2 CO + (m/z = 42), C 3 H 4 + (m/z = 40), and CHO + (m/z = 29) at 12.81, 12.80, and 13.34 eV, respectively. Statistical rate theory modeling of the breakdown diagram can also be used to predict the fractional ion abundances and thermal shifts in mass spectrometric pyrolysis studies to help assigning the m/z channels either to ionization of the neutrals or to dissociative ionization processes, with potential use for combustion diagnostics. The cationic geometry optimizations yielded functional-dependent spurious DFT minima and a deviating planar MP2 optimized geometry, which are briefly discussed.

  8. Investigating the dissociative subtype of posttraumatic stress disorder in a sample of traumatized detained youth.

    Science.gov (United States)

    Bennett, Diana C; Modrowski, Crosby A; Kerig, Patricia K; Chaplo, Shannon D

    2015-09-01

    In this study, we tested the validity of a dissociative subtype in a sample of 225 detained adolescents (142 boys, 83 girls) likely meeting full or partial criteria for posttraumatic stress disorder (PTSD). Competing theories of dissociation pose controversy regarding dissociation as a taxon versus a continuum, and results of the current study contribute to this debate by providing evidence of distinct group differences between those high and low in dissociation. Mixture modeling revealed 2 groups of youth with differing levels of depersonalization/derealization dissociative symptoms. Differences between the 2 groups of youth were investigated regarding trauma exposure and several posttraumatic reactions: posttraumatic stress symptoms (PTSS), emotion dysregulation, and emotional numbing. Compared with youth classified in the low-dissociation group, youth who exhibited high levels of dissociation demonstrated higher levels of total PTSS, posttraumatic symptom clusters of emotional numbing, intrusion, and associated features, as well as reporting more difficulties with emotion dysregulation. To test theory regarding the factors that increase the likelihood of persistent dissociation, bootstrapped regression analyses were performed to examine the possibility of an indirect effect of peritraumatic dissociation. Results consistent with statistical mediation suggested that the presence of peritraumatic dissociation at the time of trauma may contribute to the continuation of dissociative symptoms as a more generalized pattern. The results of the current study have implications for clinical treatment with traumatized youth. (c) 2015 APA, all rights reserved).

  9. Elastic and Proton-Dissociative Photoproduction of J/psi Mesons at HERA

    CERN Document Server

    Alexa, C.; Baghdasaryan, A.; Baghdasaryan, S.; Bartel, W.; Begzsuren, K.; Belousov, A.; Belov, P.; Boudry, V.; Bozovic-Jelisavcic, I.; Brandt, G.; Brinkmann, M.; Brisson, V.; Britzger, D.; Buniatyan, A.; Bylinkin, A.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Ceccopieri, F.; Cerny, K.; Chekelian, V.; Contreras, J.G.; Cvach, J.; Dainton, J.B.; Daum, K.; De Wolf, E.A.; Diaconu, C.; Dobre, M.; Dodonov, V.; Dossanov, A.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Greenshaw, T.; Grindhammer, G.; Habib, S.; Haidt, D.; Henderson, R.C.W.; Hennekemper, E.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hladky, J.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Huber, F.; Jacquet, M.; Janssen, X.; Jonsson, L.; Jung, H.; Kapichine, M.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kogler, R.; Kostka, P.; Kramer, M.; Kretzschmar, J.; Kruger, K.; Landon, M.P.J.; Lange, W.; Laycock, P.; Lebedev, A.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Lopez-Fernandez, R.; Lubimov, V.; Malinovski, E.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Morozov, A.; Morris, J.V.; Muller, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikitin, D.; Nowak, G.; Nowak, K.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Palichik, V.; Pandurovic, M.; Pascaud, C.; Patel, G.D.; Perez, E.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Polifka, R.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Ruiz Tabasco, J.E.; Rusakov, S.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.C.; Sefkow, F.; Shushkevich, S.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Staykova, Z.; Steder, M.; Stella, B.; Stoicea, G.; Straumann, U.; Sykora, T.; Thompson, P.D.; Traynor, D.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; Wegener, D.; Wunsch, E.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zlebcik, R.; Zohrabyan, H.; Zomer, F.

    2013-06-15

    Cross sections for elastic and proton-dissociative photoproduction of J/psi mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at $ep$ centre-of-mass energies sqrt{s} approx 318 GeV and sqrt{s} approx 225 GeV, corresponding to integrated luminosities of L = 130 pb^{-1} and L = 10.8 pb^{-1}, respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25< Wgp < 110 GeV. Differential cross sections $\\mathrm{d}\\sigma / \\mathrm{d}t$, where $t$ is the squared four-momentum transfer at the proton vertex, are measured in the range $|t| < 1.2 \\, \\gevsq$ for the elastic process and $|t| < 8 \\, \\gevsq$ for proton dissociation. The results are compared to other measurements. The $\\Wgp$ and $t$-dependences are parametrised using phenomenological fits.

  10. Elastic and proton-dissociative photoproduction of J/ψ mesons at HERA

    International Nuclear Information System (INIS)

    Alexa, C.; Dobre, M.; Rotaru, M.; Stoicea, G.; Andreev, V.; Belousov, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Vazdik, Y.; Baghdasaryan, A.; Baghdasaryan, S.; Zohrabyan, H.; Bartel, W.; Belov, P.; Brinkmann, M.; Britzger, D.; Campbell, A.J.; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Gouzevitch, M.; Grebenyuk, A.; Habib, S.; Haidt, D.; Kleinwort, C.; Kraemer, M.; Krueger, K.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Radescu, V.; Schmitt, S.; Sefkow, F.; Shushkevich, S.; South, D.; Steder, M.; Wuensch, E.; Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B.; Boudry, V.; Specka, A.; Bozovic-Jelisavcic, I.; Pandurovic, M.; Brandt, G.; Brisson, V.; Jacquet, M.; Pascaud, C.; Zhang, Z.; Zomer, F.; Buniatyan, A.; Huber, F.; Pirumov, H.; Sauter, M.; Schoening, A.; Bylinkin, A.; Bystritskaya, L.; Fedotov, A.; Lubimov, V.; Rostovtsev, A.; Cantun Avila, K.B.; Contreras, J.G.; Ruiz Tabasco, J.E.; Ceccopieri, F.; Wolf, E.A. de; Favart, L.; Hreus, T.; Janssen, X.; Roosen, R.; Staykova, Z.; Mechelen, P. van; Cerny, K.; Pokorny, B.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Zlebcik, R.; Chekelian, V.; Grindhammer, G.; Kiesling, C.; Cvach, J.; Hladky, J.; Reimer, P.; Zalesak, J.; Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D.; Daum, K.; Meyer, H.; Diaconu, C.; Hoffmann, D.; Sauvan, E.; Vallee, C.; Dodonov, V.; Dossanov, A.; Egli, S.; Hildebrandt, M.; Horisberger, R.; Feltesse, J.; Perez, E.; Schoeffel, L.; Ferencei, J.; Goerlich, L.; Mikocki, S.; Milcewicz-Mika, I.; Nowak, G.; Sopicki, P.; Turnau, J.; Grab, C.; Henderson, R.C.W.; Hennekemper, E.; Herbst, M.; Schultz-Coulon, H.C.; Herrera, G.; Lopez-Fernandez, R.; Hiller, K.H.; Kostka, P.; Lange, W.; Naumann, T.; Joensson, L.; Jung, H.; Kapichine, M.; Morozov, A.; Nikitin, D.; Palichik, V.; Spaskov, V.; Kogler, R.; Nowak, K.; Landon, M.P.J.; Rizvi, E.; Traynor, D.; Martyn, H.U.; Morris, J.V.; Sankey, D.P.C.; Mueller, K.; Robmann, P.; Straumann, U.; Truoel, P.; Newman, P.R.; Thompson, P.D.; Picuric, I.; Raicevic, N.; Soloviev, Y.; Stella, B.; Sykora, T.; Tsakov, I.; Wegener, D.

    2013-01-01

    Cross sections for elastic and proton-dissociative photoproduction of J/ψ mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies √(s) ∼ 318 GeV and √(s) ∼ 225 GeV, corresponding to integrated luminosities of L = 130 pb -1 and L = 10.8 pb -1 , respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25 γp 2 for the elastic process and vertical stroke t vertical stroke 2 for proton dissociation. The results are compared to other measurements. The W γp and t-dependences are parametrised using phenomenological fits. (orig.)

  11. Barrierless association of CF2 and dissociation of C2F4 by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory

    Science.gov (United States)

    Bao, Junwei Lucas; Zhang, Xin

    2016-01-01

    Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the high-pressure limit dissociation rate constant of tetrafluoroethylene (C2F4), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice–Ramsperger–Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements. PMID:27834727

  12. Dissociation of fast HeH+ ions in foils and gases

    International Nuclear Information System (INIS)

    Gemmell, D.S.; Cooney, P.J.; Pietsch, W.J.; Ratkowski, A.J.; Vager, Z.

    1978-01-01

    To gain understanding of phenomena observed when very simple light diatomic ions are incident at high velocities upon thin foils and gaseous targets, an extensive set of measurements on the dissociation products arising from beams of HeH + was made. Experimental and calculated joint distributions in energy and angle for protons emerging (near the beam direction) from an 85-A carbon foil bombarded by 2.0-MeV HeH + ions are presented

  13. The Coulomb dissociation of 8B and the 8B solar neutrino flux

    International Nuclear Information System (INIS)

    Gai, M.

    1994-01-01

    The Coulomb Dissociation of 8 B was measured using 46.5 MeV/u 8 B radioactive beams from the RIKEN-RIPS Radioactive Beam Facility, in an attempt to measure the 7 Be(p,γ) 8 B reaction at low energy, of relevance to estimating the 8 B solar neutrino flux. The experimental setup is discussed and the results are consistent with the lower value of S 17 measured by Filippone et al and Vaughn et al

  14. Tautomerism, ionization, and bond dissociations of 5-nitro-2,4-dihydro-3H-1,2,4-triazolone.

    NARCIS (Netherlands)

    Harris, N.J.; Lammertsma, K.

    1996-01-01

    Tautomerization, ionization, and bond dissociations of the insensitive high-energy explosive 5-nitro-2,4-dihydro-3H-1,2,4-triazolone (NTO) were studied by molecular orbital SCF and MP2 theories and with the Becke3LYP hybrid density functional using the 6-31+G* and 6-311+G** basis sets. Energies

  15. Coulomb Dissociation as a Tool of Nuclear Astrophysics

    International Nuclear Information System (INIS)

    Utsunomiya, H.

    2000-01-01

    My talk will begin with an introduction of the Coulomb dissociation method, proceed to discussions on Coulomb breakup of 7 Li with respect to the big-bang nucleosynthesis and end with the revision of astrophysical S-factors. The methodology based on the virtual photon source will be introduced in view of experimental techniques. The discussion will include the quantum tunnelling effect in non-resonant breakup, the lifetime of continuum states, and Coulomb distortion of relevant cross sections. Roles of multi-step processes and different multipolarities will also be discussed on the basis of solving a time-dependent Schroedinger equation. My talk will present quantitative results. The theoretical framework of the Coulomb dissociation method and a broad scope of its applications are given by G. Baur. Applications to radioactive nuclei which have quickly become vogue are discussed in the related lecture of J. Kiener. (author)

  16. Monte-Carlo simulations of geminate electron-hole pair dissociation in a molecular heterojunction: a two-step dissociation mechanism

    International Nuclear Information System (INIS)

    Offermans, Ton; Meskers, Stefan C.J.; Janssen, Rene A.J.

    2005-01-01

    The Monte-Carlo simulations are used to investigate the dissociation of a Coulomb correlated charge pair at an idealized interface between an electron accepting and an electron donating molecular material. In the simulations the materials are represented by cubic lattices of sites, with site the energies spread according to Gaussian distributions. The influence of temperature, applied external fields, and the width of the Gaussian densities of states distribution for both the electron and the hole transporting material are investigated. The results show that the dissociation of geminate charge pairs is assisted by disorder and the results can be understood in terms of a two-step model. In the first step, the slow carrier in the most disordered material jumps away from the interface. In the following, second step, the reduced Coulombic attraction allows the faster carrier in the less disordered material to escape from the interface by thermally activated hopping. When the rate for geminate recombination at the interface is very low ( -1 ) the simulations predict a high yield for carrier collection, as observed experimentally. Comparison of the simulated and experimentally observed temperature dependence of the collection efficiency indicates that at low temperature dissociation of the geminate charge pairs may be one of the factors limiting the device performance

  17. Comparison of brazilian spiritist mediumship and dissociative identity disorder.

    Science.gov (United States)

    Moreira-Almeida, Alexander; Neto, Francisco Lotufo; Cardeña, Etzel

    2008-05-01

    We studied the similarities and differences between Brazilian Spiritistic mediums and North American dissociative identity disorder (DID) patients. Twenty-four mediums selected among different Spiritistic organizations in São Paulo, Brazil, were interviewed using the Dissociative Disorder Interview Schedule, and their responses were compared with those of DID patients described in the literature. The results from Spiritistic mediums were similar to published data on DID patients only with respect to female prevalence and high frequency of Schneiderian first-rank symptoms. As compared with individuals with DID, the mediums differed in having better social adjustment, lower prevalence of mental disorders, lower use of mental health services, no use of antipsychotics, and lower prevalence of histories of physical or sexual childhood abuse, sleepwalking, secondary features of DID, and symptoms of borderline personality. Thus, mediumship differed from DID in having better mental health and social adjustment, and a different clinical profile.

  18. Awareness is relative: dissociation as the organisation of meaning.

    Science.gov (United States)

    Lesley, Joan

    2006-09-01

    This essay discusses how the organisation of mental material within the cognitive system can influence consciousness and awareness, and presents a theory of dissociation based on the premise that awareness is relative, contingent on the activated representation of the ongoing event being linked to the activated self-representation. It allows four possible variations of integration: (i) non-integrated experience--perceptions about an object/event are either not perceived or they remain at the sensory level: traditional dissociative states, amnesia, depersonalisation etc; (ii) variably integrated experience--activation of information of a specific valence about an object blocks activation of information of contrasting valence: splitting; (iii) alternatively integrated experience--experience is integrated into a specific, limited active self-representation: fugue and multiple identity states; (iv) dis-integrated experience-the ongoing experience of innate drives and needs is no longer consistently activated in the core self-representation: repression and isolation.

  19. Zn Coordination Chemistry:  Development of Benchmark Suites for Geometries, Dipole Moments, and Bond Dissociation Energies and Their Use To Test and Validate Density Functionals and Molecular Orbital Theory.

    Science.gov (United States)

    Amin, Elizabeth A; Truhlar, Donald G

    2008-01-01

    We present nonrelativistic and relativistic benchmark databases (obtained by coupled cluster calculations) of 10 Zn-ligand bond distances, 8 dipole moments, and 12 bond dissociation energies in Zn coordination compounds with O, S, NH3, H2O, OH, SCH3, and H ligands. These are used to test the predictions of 39 density functionals, Hartree-Fock theory, and seven more approximate molecular orbital theories. In the nonrelativisitic case, the M05-2X, B97-2, and mPW1PW functionals emerge as the most accurate ones for this test data, with unitless balanced mean unsigned errors (BMUEs) of 0.33, 0.38, and 0.43, respectively. The best local functionals (i.e., functionals with no Hartree-Fock exchange) are M06-L and τ-HCTH with BMUEs of 0.54 and 0.60, respectively. The popular B3LYP functional has a BMUE of 0.51, only slightly better than the value of 0.54 for the best local functional, which is less expensive. Hartree-Fock theory itself has a BMUE of 1.22. The M05-2X functional has a mean unsigned error of 0.008 Å for bond lengths, 0.19 D for dipole moments, and 4.30 kcal/mol for bond energies. The X3LYP functional has a smaller mean unsigned error (0.007 Å) for bond lengths but has mean unsigned errors of 0.43 D for dipole moments and 5.6 kcal/mol for bond energies. The M06-2X functional has a smaller mean unsigned error (3.3 kcal/mol) for bond energies but has mean unsigned errors of 0.017 Å for bond lengths and 0.37 D for dipole moments. The best of the semiempirical molecular orbital theories are PM3 and PM6, with BMUEs of 1.96 and 2.02, respectively. The ten most accurate functionals from the nonrelativistic benchmark analysis are then tested in relativistic calculations against new benchmarks obtained with coupled-cluster calculations and a relativistic effective core potential, resulting in M05-2X (BMUE = 0.895), PW6B95 (BMUE = 0.90), and B97-2 (BMUE = 0.93) as the top three functionals. We find significant relativistic effects (∼0.01 Å in bond lengths, ∼0

  20. Formation and dissociation of dust molecules in dusty plasma

    Science.gov (United States)

    Yan, Jia; Feng, Fan; Liu, Fucheng; Dong, Lifang; He, Yafeng

    2016-09-01

    Dust molecules are observed in a dusty plasma experiment. By using measurements with high spatial resolution, the formation and dissociation of the dust molecules are studied. The ion cloud in the wake of an upper dust grain attracts the lower dust grain nearby. When the interparticle distance between the upper dust grain and the lower one is less than a critical value, the two dust grains would form a dust molecule. The upper dust grain always leads the lower one as they travel. When the interparticle distance between them is larger than the critical value, the dust molecule would dissociate. Project supported by the National Natural Science Foundation of China (Grant Nos. 11205044 and 11405042), the Natural Science Foundation of Hebei Province, China (Grant Nos. A2011201006 and A2012201015), the Research Foundation of Education Bureau of Hebei Province, China (Grant No. Y2012009), the Program for Young Principal Investigators of Hebei Province, China, and the Midwest Universities Comprehensive Strength Promotion Project, China.

  1. Dissociation of Down syndrome and Alzheimer's disease effects with imaging.

    Science.gov (United States)

    Matthews, Dawn C; Lukic, Ana S; Andrews, Randolph D; Marendic, Boris; Brewer, James; Rissman, Robert A; Mosconi, Lisa; Strother, Stephen C; Wernick, Miles N; Mobley, William C; Ness, Seth; Schmidt, Mark E; Rafii, Michael S

    2016-06-01

    Down Syndrome (DS) adults experience accumulation of Alzheimer's disease (AD)-like amyloid plaques and tangles and a high incidence of dementia and could provide an enriched population to study AD-targeted treatments. However, to evaluate effects of therapeutic intervention, it is necessary to dissociate the contributions of DS and AD from overall phenotype. Imaging biomarkers offer the potential to characterize and stratify patients who will worsen clinically but have yielded mixed findings in DS subjects. We evaluated 18F fluorodeoxyglucose positron emission tomography (PET), florbetapir PET, and structural magnetic resonance (sMR) image data from 12 nondemented DS adults using advanced multivariate machine learning methods. Our results showed distinctive patterns of glucose metabolism and brain volume enabling dissociation of DS and AD effects. AD-like pattern expression corresponded to amyloid burden and clinical measures. These findings lay groundwork to enable AD clinical trials with characterization and disease-specific tracking of DS adults.

  2. Numerical simulation of MH growth/dissociation by hot water injection on the Lab. experiment

    Science.gov (United States)

    Temma, N.; Sakamoto, Y.; Komai, T.; Yamaguchi, T.; Pawar, R.; Zyvoloski, G.

    2005-12-01

    Methane Hydrate (MH) is considered to be one of the new-generation energy resources. Aiming to develop the method of extraction of methane gas from MH, laboratory experiments have been performed in order to grasp the MH property in the National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba in Japan. In this paper, we present the results of the numerical simulation of experiment using by the hot water injection. In this calculation, FEHM (Finite Element Heat and Mass transfer) code is used. This code is developed at Los Alamos National Laboratory. In this experiment, temperature, pressure and cumulative gas production were measured. From these data, we suppose that MH growth/dissociation occurred by the flow of the hot water. And we make the model of the growth/dissociation. As this model consist of many parameters, it is difficult to determine parameters. Thus, we use PEST (Parameter ESTimation ) in order to determine parameters for the model of the MH growth/ dissociation. We use temperature data of experiment, as observed data. We make two observed data sets at the beginning and later term of experiment. At the results of PEST, we obtain two sets of parameters to get good match the observed data. We think that these sets indicate both the maximum and the minimum values of the MH growth/dissociation model. And, on this range, we continue to calculate until we get the good match. Finally, we obtain the numerical model of the experiment. Also, we conducted the sensitive analysis for the MH growth/ dissociation using this model.

  3. Bibliography of molecular dissociation in heavy particle collisions, 1950--75

    Energy Technology Data Exchange (ETDEWEB)

    McDaniel, E.W.; Barnett, C.F.; Crandall, D.H.; Gilbody, H.B.; Kirkpatrick, M.I.; Phaneuf, R.A.; Thomas, E.W.

    1979-02-01

    This annotated bibliography lists published work on molecular dissociation in heavy particle collisions for the period 1950 to 1975. Sources include scientific journals, abstract compilations, conference proceedings, books, and reports. The bibliography is arranged alphabetically by author. Each entry indicates whether the work was experimental or theoretical, what energy range was covered, and what reactants were investigated. Following the bibliographical listing are indexes of reactants and authors.

  4. Bibliography of molecular dissociation in heavy particle collisions, 1950--75

    International Nuclear Information System (INIS)

    McDaniel, E.W.; Barnett, C.F.; Crandall, D.H.; Gilbody, H.B.; Kirkpatrick, M.I.; Phaneuf, R.A.; Thomas, E.W.

    1979-02-01

    This annotated bibliography lists published work on molecular dissociation in heavy particle collisions for the period 1950 to 1975. Sources include scientific journals, abstract compilations, conference proceedings, books, and reports. The bibliography is arranged alphabetically by author. Each entry indicates whether the work was experimental or theoretical, what energy range was covered, and what reactants were investigated. Following the bibliographical listing are indexes of reactants and authors

  5. Simulant molecules with trivalent or pentavalent phosphorus atoms: bond dissociation energies and other thermodynamic and structural properties from quantum chemical models.

    Science.gov (United States)

    Hahn, David K; RaghuVeer, Krishans S; Ortiz, J V

    2011-08-04

    The CBS-QB3 and G4 thermochemical models have been used to generate energetic, structural, and spectroscopic data on a set of molecules with trivalent or pentavalent phosphorus atoms that can serve as simulants of chemical warfare agents. Based on structural data, the conformational stabilities of these molecules are explained in terms of the anomeric interaction within the OPOC and OPSC fragments. For those cases where experimental data are available, comparisons have been made between calculated and previously reported vibrational frequencies. All varieties of bond dissociation energies have been examined except those for C-H and P═O bonds. In trivalent phosphorus molecules, the O-C and S-C bonds have the lowest dissociation energies. In the pentavalent phosphorus set, the S-C bonds, followed by P-S bonds, have the lowest dissociation energies. In the fluorinated simulant molecules, the P-F bond is strongest, and the P-C or O-C bonds are weakest. © 2011 American Chemical Society

  6. The Phenomenon of Pathological Dissociation in the Ancient Chinese Medicine Literature.

    Science.gov (United States)

    Fung, Hong Wang

    2018-01-01

    Dissociative symptoms and disorders have been reported in many different cultures. If pathological dissociation is naturally occurring and related to adverse experiences, such phenomena should have been witnessed and portrayed before the modern age. To investigate whether this is the case, the author made use of the rich ancient Chinese medicine literature and looked for descriptions of pathological dissociation in medical documents written by ancient Chinese medical practitioners. In this paper, the author presents six cases selected from the ancient Chinese medicine literature. The phenomenon of pathological dissociation is observed in these cases. This is the first report of case descriptions of pathological dissociation documented in Chinese cultures before 1900.

  7. Dissociative recombination of interstellar ions: electronic structure calculations for HCO+

    International Nuclear Information System (INIS)

    Kraemer, W.P.; Hazi, A.U.

    1985-01-01

    The present study of the interstellar formyl ion HCO + is the first attempt to investigate dissociative recombination for a triatomic molecular ion using an entirely theoretical approach. We describe a number of fairly extensive electronic structure calculations that were performed to determine the reaction mechanism of the e-HCO + process. Similar calculations for the isoelectronic ions HOC + and HN 2 + are in progress. 60 refs

  8. Electron Detachment Dissociation (EDD) of Fluorescently Labeled Sialylated Oligosaccharides

    Science.gov (United States)

    Zhou, Wen; Håkansson, Kristina

    2012-01-01

    We explored the application of electron detachment dissociation (EDD) and infrared multiphoton dissociation (IRMPD) tandem mass spectrometry to fluorescently labeled sialylated oligosaccharides. Standard sialylated oligosaccharides and a sialylated N-linked glycan released from human transferrin were investigated. EDD yielded extensive glycosidic cleavages and cross-ring cleavages in all cases studied, consistently providing complementary structural information compared to IRMPD. Neutral losses and satellite ions such as C – 2H ions were also observed following EDD. In addition, we examined the influence of different fluorescent labels. The acidic label 2-aminobenzoic acid (2-AA) enhanced signal abundance in negative-ion mode. However, few cross-ring fragments were observed for 2-AA labeled oligosaccharides. The neutral label 2-aminobenzamide (2-AB) resulted in more cross-ring cleavages compared to 2-AA labeled species, but not as extensive fragmentation as for native oligosaccharides, likely resulting from altered negative charge locations from introduction of the fluorescent tag. PMID:22120881

  9. Effects of electrostatic interactions on ligand dissociation kinetics

    Science.gov (United States)

    Erbaş, Aykut; de la Cruz, Monica Olvera; Marko, John F.

    2018-02-01

    We study unbinding of multivalent cationic ligands from oppositely charged polymeric binding sites sparsely grafted on a flat neutral substrate. Our molecular dynamics simulations are suggested by single-molecule studies of protein-DNA interactions. We consider univalent salt concentrations spanning roughly a 1000-fold range, together with various concentrations of excess ligands in solution. To reveal the ionic effects on unbinding kinetics of spontaneous and facilitated dissociation mechanisms, we treat electrostatic interactions both at a Debye-Hückel (DH) (or implicit ions, i.e., use of an electrostatic potential with a prescribed decay length) level and by the more precise approach of considering all ionic species explicitly in the simulations. We find that the DH approach systematically overestimates unbinding rates, relative to the calculations where all ion pairs are present explicitly in solution, although many aspects of the two types of calculation are qualitatively similar. For facilitated dissociation (FD) (acceleration of unbinding by free ligands in solution) explicit-ion simulations lead to unbinding at lower free-ligand concentrations. Our simulations predict a variety of FD regimes as a function of free-ligand and ion concentrations; a particularly interesting regime is at intermediate concentrations of ligands where nonelectrostatic binding strength controls FD. We conclude that explicit-ion electrostatic modeling is an essential component to quantitatively tackle problems in molecular ligand dissociation, including nucleic-acid-binding proteins.

  10. A functional dissociation of conflict processing within anterior cingulate cortex

    OpenAIRE

    Chobok Kim; James Kroger; Jeounghoon Kim

    2008-01-01

    Goal-directed behavior requires cognitive control to regulate neural processing when conflict is encountered. The dorsal anterior cingulate cortex (dACC) has been associated with detecting response conflict during conflict tasks. However, recent findings have indicated not only that two distinct subregions of dACC are involved in conflict processing but also that the conflict occurs at both perceptual and response levels. We clarified a functional dissociation of the caudal dACC (cdACC) and t...

  11. Adsorption and dissociation of H2O on Al(1 1 1) surface by density functional theory calculation

    International Nuclear Information System (INIS)

    Guo, F.Y.; Long, C.G.; Zhang, J.; Zhang, Z.; Liu, C.H.; Yu, K.

    2015-01-01

    Highlights: • O 2 on Al(1 1 1) surface can spontaneously dissociate, but H 2 O can not. • H 2 O, OH and H on top sites are favorable on Al(1 1 1) surface. • O on the hollow (fcc) site is preferred. • O which plays a key role in the dissociate reaction of H 2 O. - Abstract: Using the first-principles calculations method based on the density functional theory, we systematically study the adsorption behavior of a single molecular H 2 O on a clean and a pre-adsorbed O atom Al(1 1 1) surface, and also its corresponding dissociation reactions. The equilibrium configuration on top, bridge, and hollow (fcc and hcp) site were determined by relaxation of the system relaxation. The adsorptions of H 2 O, OH and H on top sites are favorable on the Al(1 1 1) surface, while that of O on the hollow (fcc) site is preferred. The results show that the hydrogen atom dissociating from H 2 O needs a 248.32 kJ/mol of energy on clean Al(1 1 1) surface, while the dissociating energy decreases to 128.53 kJ/mol with the aid of the O absorption. On the other hand, these phenomena indicate that the dehydrogenated reaction energy barrier of the pre-adsorbed O on metal surface is lower than that of on a clean one, because O can promote the dehydrogenation of H 2 O

  12. [Variations in Posner's test for diagnosis of dissociated strabismus].

    Science.gov (United States)

    González-González, José Manuel; Arroyo-Yllanes, María Estela; Pérez-Pérez, José Fernando

    2013-01-01

    A particular feature of dissociated strabismus is that the frequency of presentation and its magnitude is variable. It is common to find that in certain examinations is very obvious, and in others not so much. To facilitate exploration some maneuvers are described: Bielchowsky's maneuver, Bielchowsky's phenomenon and Posner test. to compare the presence and magnitude of the ocular movement in dissociated strabismus in Posner's Test using opaque versus translucent occluders. Prospective, transversal, descriptive study. Patients with diagnosis of were included. Posner's test in two ways: 1) With opaque occluders, and 2) with translucent occluders was perforned. Ninety-five percent of the patients presented horizontal deviation. Posner's test with opaque occluder was positive in all cases (100%). Posner's test with translucent occluders was positive in 94% of the patients (p= 8). The magnitude of the ocular movement was significantly smaller using translucent occluders than opaque occluders. (p= 0.0001). The Posner's test using opaque occluders was more efective to demonstrate clearly and precisely the size of the ocular movement in dissociated strabismus.

  13. Neurodevelopmental origins of abnormal cortical morphology in dissociative identity disorder.

    Science.gov (United States)

    Reinders, A A T S; Chalavi, S; Schlumpf, Y R; Vissia, E M; Nijenhuis, E R S; Jäncke, L; Veltman, D J; Ecker, C

    2018-02-01

    To examine the two constitutes of cortical volume (CV), that is, cortical thickness (CT) and surface area (SA), in individuals with dissociative identity disorder (DID) with the view of gaining important novel insights into the underlying neurobiological mechanisms mediating DID. This study included 32 female patients with DID and 43 matched healthy controls. Between-group differences in CV, thickness, and SA, the degree of spatial overlap between differences in CT and SA, and their relative contribution to differences in regional CV were assessed using a novel spatially unbiased vertex-wise approach. Whole-brain correlation analyses were performed between measures of cortical anatomy and dissociative symptoms and traumatization. Individuals with DID differed from controls in CV, CT, and SA, with significantly decreased CT in the insula, anterior cingulate, and parietal regions and reduced cortical SA in temporal and orbitofrontal cortices. Abnormalities in CT and SA shared only about 3% of all significantly different cerebral surface locations and involved distinct contributions to the abnormality of CV in DID. Significant negative associations between abnormal brain morphology (SA and CV) and dissociative symptoms and early childhood traumatization (0 and 3 years of age) were found. In DID, neuroanatomical areas with decreased CT and SA are in different locations in the brain. As CT and SA have distinct genetic and developmental origins, our findings may indicate that different neurobiological mechanisms and environmental factors impact on cortical morphology in DID, such as early childhood traumatization. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Kinetics of Huperzine A Dissociation from Acetylcholinesterase via Multiple Unbinding Pathways.

    Science.gov (United States)

    Rydzewski, Jakub; Jakubowski, Rafal; Nowak, Wieslaw; Grubmüller, Helmut

    2018-05-01

    The dissociation of huperzine A (hupA) from Torpedo californica acetylcholinesterase (TcAChE) was investigated by 4-microsecond unbiased and biased all-atom molecular dynamics (MD) simulations in explicit solvent. We performed our study using memetic sampling (MS) for the determination of reaction pathways (RPs), metadynamics to calculate free energy, and maximum-likelihood estimation (MLE) to recover kinetic rates from unbiased MD simulations. Our simulations suggest that the dissociation of hupA occurs mainly via two RPs: a front-door along the axis of the active-site gorge (pwf) and through a new transient side-door (pws), i.e., formed by the Omega-loop (residues 67--94 of TcAChE). Analysis of the inhibitor unbinding along the RPs suggests that pws is opened transiently after hupA and the Omega-loop reach a low free-energy transition state characterized by the orientation of the pyridone group of the inhibitor directed toward the Omega-loop plane. Unlike pws, pwf does not require large structural changes of TcAChE to be accessible. The estimated free energies and rates agree well with available experimental data. The dissociation rates along the unbinding pathways are similar, suggesting that the dissociation of hupA along pws is likely to be relevant. This indicates that perturbations to hupA-TcAChE interactions could potentially induce pathway hopping. In summary, out results characterize the slow-onset inhibition of TcAChE by hupA, which may provide the structural and energetic basis for the rational design of the next-generation slow-onset inhibitors with optimized pharmacokinetic properties for the treatment of Alzheimer's disease.

  15. Determination of the barrier height for acetyl radical dissociation from acetyl chloride photodissociation at 235 nm using velocity map imaging.

    Science.gov (United States)

    Tang, Xiaonan; Ratliff, Britni J; FitzPatrick, Benjamin L; Butler, Laurie J

    2008-12-18

    This work uses velocity map imaging to determine the barrier height for acetyl radical, CH3CO, dissociation to CH3 + CO. Photodissociation of acetyl chloride at 235 nm generates acetyl radicals with an internal energy distribution spanning this barrier. We determine the velocity and internal energy distribution of all nascent acetyl radicals, stable and unstable, by measuring the velocities of the Cl(2P3/2) and Cl(2P1/2) cofragments. These Cl cofragments are detected with 2 + 1 resonance-enhanced multiphoton ionization (REMPI) in a spin-orbit branching ratio Cl(2P3/2):Cl(2P1/2) of 3.3 +/- 0.2. Using 157 nm photoionization, we then detect the recoil velocities of the energetically stable acetyl radicals. The radicals and momentum matched Cl atoms evidence parallel angular distributions. Comparison of the total recoil translational energy distribution P(E(T)) for all radicals to that obtained from the detection of stable radicals yields an onset for dissociation at a translational energy of 25.0 +/- 0.4 kcal/mol. From this onset we can calculate the barrier height for CH3CO --> CH3 + CO, but this relies on prior determinations of the C-Cl bond energy of acetyl chloride. Using an experimental bond dissociation energy of 83.4 +/- 0.2 kcal/mol yields a dissociation barrier of 14.2 +/- 0.5 kcal/mol. Our data evidence that a portion of the acetyl radicals formed with total internal energy above the barrier are stable due to the partitioning of energy into rotation during the C-Cl bond fission of the precursor. Thus, the internal energy onset for dissociation is not as sharp as was assumed in prior determinations of the barrier. The experimentally determined onset is compared with that predicted from electronic structure calculations at the G3//B3LYP and CCSD(T) levels of theory.

  16. Electron detachment dissociation of fluorescently labeled sialylated oligosaccharides.

    Science.gov (United States)

    Zhou, Wen; Håkansson, Kristina

    2011-12-01

    We explored the application of electron detachment dissociation (EDD) and infrared multiphoton dissociation (IRMPD) tandem mass spectrometry to fluorescently labeled sialylated oligosaccharides. Standard sialylated oligosaccharides and a sialylated N-linked glycan released from human transferrin were investigated. EDD yielded extensive glycosidic cleavages and cross-ring cleavages in all cases studied, consistently providing complementary structural information compared with infrared multiphoton dissociation. Neutral losses and satellite ions such as C-2H ions were also observed following EDD. In addition, we examined the influence of different fluorescent labels. The acidic label 2-aminobenzoic acid (2-AA) enhanced signal abundance in negative-ion mode. However, few cross-ring fragments were observed for 2-AA-labeled oligosaccharides. The neutral label 2-aminobenzamide (2-AB) resulted in more cross-ring cleavages compared with 2-AA-labeled species, but not as extensive fragmentation as for native oligosaccharides, likely resulting from altered negative charge locations from introduction of the fluorescent tag. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Co-occurrence of dissociative identity disorder and borderline personality disorder.

    Science.gov (United States)

    Ross, Colin A; Ferrell, Lynn; Schroeder, Elizabeth

    2014-01-01

    The literature indicates that, among individuals with borderline personality disorder, pathological dissociation correlates with a wide range of impairments and difficulties in psychological function. It also predicts a poorer response to dialectical behavior therapy for borderline personality disorder. We hypothesized that (a) dissociative identity disorder commonly co-occurs with borderline personality disorder and vice versa, and (b) individuals who meet criteria for both disorders have more comorbidity and trauma than individuals who meet criteria for only 1 disorder. We interviewed a sample of inpatients in a hospital trauma program using 3 measures of dissociation. The most symptomatic group was those participants who met criteria for both borderline personality disorder and dissociative identity disorder on the Dissociative Disorders Interview Schedule, followed by those who met criteria for dissociative identity disorder only, then those with borderline personality disorder only, and finally those with neither disorder. Greater attention should be paid to the relationship between borderline personality disorder and dissociative identity disorder.

  18. Study of photoionization and dissociative photoionization of carbon monoxide from ionization threshold to 38 eV by using synchrotron radiation

    International Nuclear Information System (INIS)

    Zhao, Yujie; Cao, Maoqi; Li, Yuquan; Shan, Xiaobin; Liu, Fuyi; Sheng, Liusi; Li, Li; Liu, Wanfang

    2014-01-01

    Highlights: • The high resolution photoionization spectrum of carbon monoxide has been investigated using tunable synchrotron radiation. • This work has investigated comprehensively almost all kinds of photo excitation processes of CO in wide photon region. • The mechanisms of photoionization and dissociative photoionization of CO have been researched in detail. - Abstract: The vacuum-ultraviolet photoionization and dissociative photoionization of carbon monoxide in a region 14–38 eV have been investigated with time-of-flight (TOF) photoionization mass spectrometry (PIMS) using tunable synchrotron radiation (SR). The adiabatic ionization energy (IE) of carbon monoxide and appearance energies (AE) for its fragment ions in different states are determined by measurements of photoionization efficiency spectra (PIES). Ab initio calculations have been performed to investigate the reaction mechanism of dissociative photoionization of carbon monoxide. On the basis of experimental and predicted theoretical results, the mechanisms of photoionization and dissociative photoionization of molecular CO are discussed, and sixteen dissociative photoionization processes are proposed. The equilibrium geometries and harmonic vibrational frequencies of CO molecule, and its parent cation were calculated by using MP2 (full) method. The differences of configurations between them are also discussed on the basis of theoretical calculations. According to our results, the experimental IE of CO molecule, and dissociation energies (E d ) of possible dissociative channels are in reasonable agreement with the calculated values of the proposed photodissociation channels

  19. Low-energy electron-induced dissociation in condensed-phase L-cysteine II: a comparative study on anion desorption from chemisorbed and physisorbed films

    Science.gov (United States)

    Alizadeh, Elahe; Massey, Sylvain; Sanche, Léon; Rowntree, Paul A.

    2016-04-01

    Due to its multifunctional structure, cysteine is becoming an ideal model molecule for investigating the complex interactions of proteins with metallic surfaces such as gold nanoparticles. We report herein the results of low-energy electron induced degradation of L-cysteine films, chemisorbed on a gold substrate via the thiol group or physisorbed into a clean gold surface. The data were recorded under ultra-high vacuum conditions at room temperature. Anion yields desorbed from these films by the impact of 0.5 to 19 eV electrons provide clear evidence of the efficient decomposition of this amino acid via dissociative electron attachment (i.e., from dissociation of intermediate transient anions located between 5 and 14 eV). The peaks in the desorbed-anion yield functions, associated with DEA, are superimposed on a continuously rising signal attributed to dipolar dissociation. Similar to the results previously observed from physisorbed films, light anionic species, with masses lower than 35 amu, have been detected. In addition, we measured for first time fragments at 14 amu (CH2-) and 15 amu (CH3-) desorbing from physisorbed films, as well as heavier fragments of mass 45 and 46 amu desorbing from chemisorbed films. Contribution to the Topical Issue "Low-Energy Interactions related to Atmospheric and Extreme Conditions", edited by S. Ptasinska, M. Smialek-Telega, A. Milosavljevic, B. Sivaraman.

  20. The Flail and Pulseless Upper Limb: an Extreme Case of Traumatic Scapulo-thoracic Dissociation

    Directory of Open Access Journals (Sweden)

    Maria SW

    2015-07-01

    Full Text Available Scapulo-thoracic dissociation is an infrequent injury resulting from high energy trauma which is often associated with severe neurological and vascular injuries which may be unrecognised at the time of presentation. A 24 year-old female presented with bilateral rib fractures, pneumothorax, liver and kidney injuries following a road traffic accident. She also sustained fractures of her right scapula, odontoid, right transverse processes of the thoracic and lumbar vertebrae and a closed fracture of her right femur. Her right upper limb was later noted to be flail and pulseless, due to complete right brachial plexus injury, scapula-thoracic dissociation and subclavian artery avulsion. We managed the upper limb injuries non-operatively, and focused on resuscitation of the patient. Early exploration of the complete brachial plexus injury was not undertaken in spite of the possible associated poor functional outcome as there was no life-threatening indication.

  1. Recent progress in the theory of dissociative attachment: From diatomics to biomolecules

    International Nuclear Information System (INIS)

    Fabrikant, Ilya I

    2010-01-01

    We present a summary of recent progress in theoretical studies of low-energy dissociative electron attachment (DEA) to halogen molecules and polyatomic molecules based on the resonance R-matrix theory. It explains many observed features in DEA cross sections including low-energy behavior, threshold resonances and cusps. It also gives correct description of the temperature dependence of the attachment rate coefficients. More recently the theory was applied to two molecules of biological interest, formic acid and glycine. DEA mechanisms in these systems are very similar to those in hydrogen halides.

  2. Mapping the dissociative ionization dynamics of molecular nitrogen with attosecond resolution

    International Nuclear Information System (INIS)

    Klinker, M; González-Vázquez, J; Martin, F; Trabattoni, A; Sansone, G; Nisoli, M; Liu, C; Linguerri, R; Hochlaf, M; Klei, J; Vrakking, M J J; Calegari, F

    2015-01-01

    We wish to understand the processes underlying the ionization dynamics of N 2 as experimentally induced and studied by recording the kinetic energy release (KER) in a XUV-pump/IR-probe setup. To this end a theoretical model was developed describing the ionization process using Dyson Orbitals and, subsequently, the dissociation process using a large set of diabatic potential energy surfaces (PES) on which to propagate. From said set of PES, a small subset is extracted allowing for the identification of one and two photon processes chiefly responsible for the experimentally observed features. (paper)

  3. Type of presentation of dissociative disorder and frequency of co-morbid depressive disorder.

    Science.gov (United States)

    Alvi, Tabassum; Minhas, Fareed Aslam

    2009-02-01

    To determine the frequency distribution of various types of dissociative disorders, along with existing co-morbid depression and its level of severity in patients with dissociative disorder. Observational, cross-sectional study. The Institute of Psychiatry, Rawalpindi General Hospital from October 2004 to March 2005. Fifty consecutive patients were included in the study through non-probable purposive sampling technique. Encounter form included socio-demographic profile and brief psychiatric history. ICD 10 diagnostic criteria for research were administered for determining the presentation of dissociative disorder. Present state examination was applied to make diagnosis of depressive disorder in the studied patients. Descriptive statistics for frequency analysis of sociodemographic variables, type of presentation of dissociative disorder and the frequency of depressive disorder in patients of dissociative disorder. The mean age was 23.6+/-8.67 years with female preponderance (n=40, 80% patients). Most of them were single, unemployed and belonged to urban population. Main stress was primary support group issue. Mixed category of dissociative disorder was highest (n=18, 38%) followed by unspecified and motor symptoms (n=13, 26%) in each group. Depression was present in 42 (84%) patients. Moderate depression was most frequent (n=19, 38%). Mixed dissociative symptoms were found in 38%, while 26% had motor and unspecified category of dissociative symptoms respectively. Depressive disorder was present in 42 (84%) cases of dissociative disorder with 38% having moderate depression.

  4. Effect of transition metal-doped Ni(211) for CO dissociation: Insights from DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kuiwei; Zhang, Minhua [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Yu, Yingzhe, E-mail: yzhyu@tju.edu.cn [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China)

    2017-03-31

    Highlights: • Doping the step edge of Ni(211) with Fe or Ru observably enhances CO dissociation. • Rh doping is unfavorable for CO activation both kinetically and thermodynamically. • Two neat linear relations are proposed besides the Brønsted–Evans–Polanyi relation. • The differences of CO adsorption are rationalized via the Blyholder model. - Abstract: Density functional theory slab calculations were performed to investigate the adsorption and dissociation of CO over pure and M-doped Ni(211) (M = Fe, Co, Ru and Rh) with the aim to elucidate the effect of transition metal doping for CO activation. Doping the step edge of Ni(211) with Fe, Co and Ru is found to enhance the binding of CO in the initial state (IS) (in the sequence by the improvement degree: Fe > Ru > Co) as well as the co-adsorption of C and O in the final state (FS) (Ru > Fe > Co). In contrast, Rh doping is unfavorable both in the IS and in the FS. Analysis of the overall potential energy surfaces (PES) suggests CO dissociation is facilitated by Fe, Ru and Co doping both kinetically and thermodynamically, wherein Fe and Ru behave extraordinary. Interestingly, Fe substitute is slightly superior to Ru in kinetics whereas the contrary is the case in thermodynamics. Rh doping elevates the energy height from 0.97 eV on Ni(211) to 1.32 eV and releases 0.39 eV less heat relative to Ni(211), again manifesting a negative effect. Besides the classical Brønsted–Evans–Polanyi relationship, we put forward another two neat linear relations, which can well describe the feature of CO dissociation. The differences of CO adsorption and activation in the IS over pure and doped Ni(211) surfaces are rationalized via electronic structure analysis. The findings presented herein are expected to provide theoretical guidance for catalyst design and optimization in relevant processes.

  5. The effect of the two tailored femtosecond laser pulses in the enhancement of methane dissociation

    International Nuclear Information System (INIS)

    Sadighi-Bonabi, R.; Dehghani, Z.; Irani, E.

    2010-01-01

    Complete text of publication follows. Based on the gradient optimization method a useful approach for dissociation of the methane molecule is introduced. This analytical model produces an optimized two tailored rectangular laser pulses which dissociates the molecular ion CH 4 + with maximum probability of 1. In this approach the field assisted dissociation is used by a semi-classical view. It is assumed that only the selective dissociative bond is in direction of the laser electric field are effective. Saturation is found for dissociation of the mentioned molecular bond, where the first pulse should have higher intensity than the second pulse. In addition to that, the sensitivity of the dissociation probability to the initial bond length and the control of the desired product channel by variation of the laser intensity and its duration of laser field is presented.

  6. Dissociative photoionization of quinoline and isoquinoline

    NARCIS (Netherlands)

    Bouwman, J.; Sztáray, B.; Oomens, J.; Hemberger, P.; Bodi, A.

    2015-01-01

    Two nitrogen-containing polycyclic aromatic hydrocarbon isomers of C9H7N composition, quinoline, and isoquinoline have been studied by imaging photoelectron photoion coincidence spectroscopy at the VUV beamline of the Swiss Light Source. High resolution threshold photoelectron spectra have been

  7. Dissociative photoionization of 1,3-butadiene: experimental and theoretical insights.

    Science.gov (United States)

    Fang, Wenzheng; Gong, Lei; Zhang, Qiang; Shan, Xiaobin; Liu, Fuyi; Wang, Zhenya; Sheng, Liusi

    2011-05-07

    The vacuum-ultraviolet photoionization and dissociative photoionization of 1,3-butadiene in a region ∼8.5-17 eV have been investigated with time-of-flight photoionization mass spectrometry using tunable synchrotron radiation. The adiabatic ionization energy of 1,3-butadiene and appearance energies for its fragment ions, C(4)H(5)(+), C(4)H(4)(+), C(4)H(3)(+), C(3)H(3)(+), C(2)H(4)(+), C(2)H(3)(+), and C(2)H(2)(+), are determined to be 9.09, 11.72, 13.11, 15.20, 11.50, 12.44, 15.15, and 15.14 eV, respectively, by measurements of photoionization efficiency spectra. Ab initio molecular orbital calculations have been performed to investigate the reaction mechanism of dissociative photoionization of 1,3-butadiene. On the basis of experimental and theoretical results, seven dissociative photoionization channels are proposed: C(4)H(5)(+) + H, C(4)H(4)(+) + H(2), C(4)H(3)(+) + H(2) + H, C(3)H(3)(+) + CH(3), C(2)H(4)(+) + C(2)H(2), C(2)H(3)(+) + C(2)H(2) + H, and C(2)H(2)(+) + C(2)H(2) + H(2). Channel C(3)H(3)(+) + CH(3) is found to be the dominant one, followed by C(4)H(5)(+) + H and C(2)H(4)(+) + C(2)H(2). The majority of these channels occur via isomerization prior to dissociation. Transition structures and intermediates for those isomerization processes were also determined.

  8. Investigation of diffractive pion dissociation at COMPASS

    Energy Technology Data Exchange (ETDEWEB)

    Weitzel, Quirin; Austregesilo, Alexander; Dinkelbach, Anna-Maria; Friedrich, Jan; Gerassimov, Sergei; Grabmueller, Stefanie; Haas, Florian; Hoeppner, Christian; Ketzer, Bernhard; Konorov, Igor; Kraemer, Markus; Kuhn, Roland; Mann, Alexander; Nagel, Thiemo; Neubert, Sebastian; Paul, Stephan [Technische Universitaet Muenchen, Physik-Department E18, 85748 Garching (Germany); Chung, Suh-Urk [Technische Universitaet Muenchen, Physik-Department E18, 85748 Garching (Germany)]|[Brookhaven National Laboratory, Upton, NY 11973 (United States); Ryabchikov, Dmitri [Institute for High Energy Physics, 142284 Protvino (Russian Federation)

    2008-07-01

    COMPASS is a fixed-target experiment at the CERN SPS, which investigates the structure and spectroscopy of hadrons. In 2004, a first run with a 190 GeV/c {pi}{sup -} beam took place, using nuclear targets. Diffractive reactions in COMPASS provide clean access to meson resonances with masses below 2.5 GeV/c{sup 2}, where candidates for spin-exotic states (e. g. 1{sup -+}) have been reported in the past. Within a few days of data taking, a competitive number of events on lead with {pi}{sup -}{pi}{sup -}{pi}{sup +} final states were recorded. In this talk we report on the results of a first partial wave analysis of this data set.

  9. Dissociation of binding and learning processes.

    Science.gov (United States)

    Moeller, Birte; Frings, Christian

    2017-11-01

    A single encounter of a stimulus together with a response can result in a short-lived association between the stimulus and the response [sometimes called an event file, see Hommel, Müsseler, Aschersleben, & Prinz, (2001) Behavioral and Brain Sciences, 24, 910-926]. The repetition of stimulus-response pairings typically results in longer lasting learning effects indicating stimulus-response associations (e.g., Logan & Etherton, (1994) Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 1022-1050]. An important question is whether or not what has been described as stimulus-response binding in action control research is actually identical with an early stage of incidental learning (e.g., binding might be seen as single-trial learning). Here, we present evidence that short-lived binding effects can be distinguished from learning of longer lasting stimulus-response associations. In two experiments, participants always responded to centrally presented target letters that were flanked by response irrelevant distractor letters. Experiment 1 varied whether distractors flanked targets on the horizontal or vertical axis. Binding effects were larger for a horizontal than for a vertical distractor-target configuration, while stimulus configuration did not influence incidental learning of longer lasting stimulus-response associations. In Experiment 2, the duration of the interval between response n - 1 and presentation of display n (500 ms vs. 2000 ms) had opposing influences on binding and learning effects. Both experiments indicate that modulating factors influence stimulus-response binding and incidental learning effects in different ways. We conclude that distinct underlying processes should be assumed for binding and incidental learning effects.

  10. A density functional study on adsorption and dissociation of O 2 on Ir(1 0 0) surface

    Science.gov (United States)

    Erikat, I. A.; Hamad, B. A.; Khalifeh, J. M.

    2011-06-01

    The adsorption and the reaction barrier for the dissociation of O 2 on Ir(1 0 0) surface are studied using periodic self-consistent density functional theory (DFT) calculations. Dissociative adsorption is found to be energetically more favorable compared to molecular adsorption. Parallel approaches Prl1 and Prl2 on a hollow site with the same adsorption energy of -3.93 eV for both of them are found to have the most energetically preferred sites of adsorptions among all the studied cases. Hybridization between p-O 2 and d-metal orbitals is responsible for the dissociative adsorption. The minimum energy path is determined by using the nudge elastic band method (NEB). We found that the dissociation occurs immediately and very early in the dissociation path with a small activation barrier (0.26 eV), which means that molecular adsorption of O 2 on Ir(1 0 0) surface occurs at very low temperatures; this is consistent with previous experimental and theoretical studies on Ir surfaces.

  11. Psychiatric comorbidity in patients with conversion disorder and prevalence of dissociative symptoms.

    Science.gov (United States)

    Yayla, Sinan; Bakım, Bahadır; Tankaya, Onur; Ozer, Omer Akil; Karamustafalioglu, Oguz; Ertekin, Hulya; Tekin, Atilla

    2015-01-01

    The 1st objective of the current study was to investigate the frequency and types of dissociative symptoms in patients with conversion disorder (CD). The 2nd objective of the current study was to determine psychiatric comorbidity in patients with and without dissociative symptoms. A total of 54 consecutive consenting patients primarily diagnosed with CD according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria who were admitted to the psychiatric emergency outpatient clinic of Sisli Etfal Research and Teaching Hospital (Istanbul, Turkey) were included in the study. The Structured Clinical Interview for DSM-IV Axis I Disorders, Structured Interview for DSM-IV Dissociative Disorders, and Dissociative Experiences Scale were administered. Study groups consisted of 20 patients with a dissociative disorder and 34 patients without a diagnosis of any dissociative disorder. A total of 37% of patients with CD had any dissociative diagnosis. The prevalence of dissociative disorders was as follows: 18.5% dissociative disorder not otherwise specified, 14.8% dissociative amnesia, and 3.7% depersonalization disorder. Significant differences were found between the study groups with respect to comorbidity of bipolar disorder, past hypomania, and current and past posttraumatic stress disorder (ps = .001, .028, .015, and .028, respectively). Overall comorbidity of bipolar disorder was 27.8%. Psychiatric comorbidity was higher and age at onset was earlier among dissociative patients compared to patients without dissociative symptoms. The increased psychiatric comorbidity and early onset of conversion disorder found in patients with dissociative symptoms suggest that these patients may have had a more severe form of conversion disorder.

  12. Dissociative part-dependent biopsychosocial reactions to backward masked angry and neutral faces : An fMRI study of dissociative identity disorder

    NARCIS (Netherlands)

    Schlumpf, Yolanda R.; Nijenhuis, Ellert R. S.; Chalavi, Sima; Weder, Ekaterina V.; Zimmermann, Eva; Luechinger, Roger; La Marca, Roberto; Reinders, A. A. T. Simone; Jaencke, Lutz

    2013-01-01

    Objective: The Theory of Structural Dissociation of the Personality (TSDP) proposes that dissociative identity disorder (DID) patients are fixed in traumatic memories as "Emotional Parts" (EP), but mentally avoid these as "Apparently Normal Parts" of the personality (ANP). We tested the hypotheses

  13. Dissociation energies and potential energy functions for the ground X {sup 1}Σ{sup +} and “avoided-crossing” A {sup 1}Σ{sup +} states of NaH

    Energy Technology Data Exchange (ETDEWEB)

    Walji, Sadru-Dean; Sentjens, Katherine M.; Le Roy, Robert J. [Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-01-28

    A direct-potential-fit analysis of all accessible data for the A {sup 1}Σ{sup +} − X {sup 1}Σ{sup +} system of NaH and NaD is used to determine analytic potential energy functions incorporating the correct theoretically predicted long-range behaviour. These potentials represent all of the data (on average) within the experimental uncertainties and yield an improved estimate for the ground-state NaH well depth of D{sub e} = 15797.4 (±4.3) cm{sup −1}, which is ∼20 cm{sup −1} smaller than the best previous estimate. The present analysis also yields the first empirical determination of centrifugal (non-adiabatic) and potential-energy (adiabatic) Born-Oppenheimer breakdown correction functions for this system, with the latter showing that the A-state electronic isotope shift is −1.1(±0.6) cm{sup −1} going from NaH to NaD.

  14. Dissociation kinetics of acyclic and macrocyclic polyaminopolycarboxylate complexes of yttrium

    International Nuclear Information System (INIS)

    Pathak, P.N.; Manchanda, V.K.

    2000-01-01

    Dissociation kinetics of Y III complexes of a linear as well as two macrocyclic polyaminopolycarboxylates, ethylenediamine diacetic acid (EDDA), 1,7-diaza-4,10,13-trioxacyclopentadecane-N,N'-diacetic acid (K21DA) and 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N'-diacetic acid (K22DA) have been studied at a constant ionic strength (0.1 M) under varying (H + ) and temperatures. Cu II ion acts as the scavenger of the free ligand. Dissociation rate of Y III -K21DA is insensitive to Cu II and acetate (used as buffer anion) concentrations. Kinetic stability of the three complexes follow the order : Y III -K22DA>Y III -K21DA>Y III -EDDA. Enthalpies of activation for K21DA and K22DA complexes of Y III are also evaluated. Thermodynamic stability constant (log K) for Y III -K22DA complex is 10.81 ± 0.04. (author)

  15. Development of technology for ammonium nitrate dissociation process

    International Nuclear Information System (INIS)

    Zakharkin, B.S.; Varykhanov, V.P.; Kucherenko, V.S.; Solov'yeva, L.N.; Revyakin, V.V.

    2000-01-01

    Ammonia and ammonium carbonate are frequently used as reagents in fuel production and processing of liquid radioactive wastes. In particular, liquid radioactive wastes that contain ammonium nitrate are generated during operations of metal precipitation. In closed vessels at elevated temperature, for example in evaporators or deposits in tubing, ammonium nitrate may explode due to generation of gaseous nitrogen oxides [2]. In this connection, steps have to be taken to rule out conditions that result in explosion. To do that, ammonium nitrate should be removed even prior to the initial stage of its formation. This report gives results of development of a method of dissociating ammonium nitrate

  16. Stability and dissociation dynamics of N{sub 2}{sup ++} ions following core ionization studied by an Auger-electron–photoion coincidence method

    Energy Technology Data Exchange (ETDEWEB)

    Iwayama, H.; Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, Nishigonaka 38, Myodaiji, Okazaki 444-8585 (Japan); SOKENDAI, Nishigonaka 38, Myodaiji, Okazaki 444-8585 (Japan); Kaneyasu, T. [SAGA Light Source, Tosu 841-0005 (Japan); Hikosaka, Y. [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194 (Japan)

    2016-07-21

    An Auger-electron–photoion coincidence (AEPICO) method has been applied to study the stability and dissociation dynamics of dicationic states after the N K-shell photoionization of nitrogen molecules. From time-of-flight and kinetic energy analyses of the product ions, we have obtained coincident Auger spectra associated with metastable states of N{sub 2}{sup ++} ions and dissociative states leading to N{sub 2}{sup ++} → N{sup +} + N{sup +} and N{sup ++} + N. To investigate the production of dissociative states, we present two-dimensional AEPICO maps which reveal the correlations between the binding energies of the Auger final states and the ion kinetic energy release. These correlations have been used to determine the dissociation limits of individual Auger final states.

  17. [Factitious disorders in dermatology: Value of the dissociative state concept].

    Science.gov (United States)

    Fekih-Romdhane, F; Homri, W; Labbane, R

    2016-03-01

    Factitious disorders in dermatology consist of intentionally self-inflicted skin lesions that vary in morphology and distribution and occur on surfaces readily accessible to the patient's hands. They tend to be a chronic condition that waxes and wanes according to the circumstances of the patient's life. Patient management poses a particular challenge to the clinician and the prognosis is considered poor. The aetiopathogenesis of factitious disorders in dermatology is not completely understood. We present a case in which we suggested the occurrence of factitious behaviour during a dissociative state, and we briefly describe our diagnostic and therapeutic approach. A 48-year-old unemployed woman was referred to our department of psychiatry by her dermatologist for suspected factitious disorder. The patient was diagnosed with diabetes mellitus type 1 and had been hospitalized repeatedly for confirmed diabetic ketoacidosis. The onset of the disease was related to marital discord with her spouse. Numerous skin lesions had appeared on her face, arms, legs, neck and back. These lesions resulted in multiple hospital admissions and in amputation of her left leg. The condition had worsened considerably after her separation from her husband. During the initial conversation, the patient was unable to provide a clear history of the disease. She denied any knowledge of the circumstances in which these skin lesions appeared, and she did not admit self-infliction. Her mood was depressed and her speech was slow. We suspected that our patient was herself causing her skin lesions while in a dissociative state. Several arguments militate in favour of our hypothesis, particularly her history of childhood maltreatment and the association of traumatic life events with simultaneous deterioration of the skin. The explanation of the dissociative mechanism helped us to strengthen the therapeutic relationship. Within a few days, we noted a slow regression of the lesions, but the patient was

  18. A cross-cultural test of the trauma model of dissociation.

    Science.gov (United States)

    Ross, Colin A; Keyes, Benjamin B; Yan, Heqin; Wang, Zhen; Zou, Zheng; Xu, Yong; Chen, Jue; Zhang, Haiyin; Xiao, Zeping

    2008-01-01

    In order to test the trauma model of dissociation, the authors compared two samples with similar rates of reported childhood physical and sexual abuse: 502 members of the general population in Winnipeg, Canada, and 304 psychiatric outpatients at Shanghai Mental Health Center in Shanghai, China. There is virtually no popular or professional knowledge of dissociative identity disorder in China, and therefore professional and popular contamination cannot be operating. According to the trauma model, samples from different cultures with similar levels of trauma should report similar levels of dissociation. According to the sociocognitive model, in contrast, pathological dissociation is not related to trauma and should be absent in samples free of cultural and professional contamination. Of the 304 Chinese respondents, 14.5% reported childhood physical and/or sexual abuse compared to 12.5% of the Canadian sample. Both samples reported similar levels of dissociation on the Dissociative Experiences Scale and the Dissociative Disorders Interview Schedule. The findings support a specific prediction of the trauma model of dissociation not tested in previous research, and are not consistent with the sociocognitive, contamination or iatrogenic models of dissociative identity disorder.

  19. Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

    International Nuclear Information System (INIS)

    Chakrabarty, Aurab; Bouhali, Othmane; Mousseau, Normand; Becquart, Charlotte S.; El-Mellouhi, Fedwa

    2016-01-01

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structural defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from

  20. Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarty, Aurab, E-mail: aurab.chakrabarty@qatar.tamu.edu; Bouhali, Othmane [Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Mousseau, Normand [Département de Physique and RQMP, Université de Montréal, Case Postale 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7 (Canada); Becquart, Charlotte S. [UMET, UMR CNRS 8207, ENSCL, Université Lille I, 59655 Villeneuve d' Ascq Cédex (France); El-Mellouhi, Fedwa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825, Doha (Qatar)

    2016-08-07

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structural defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from

  1. First-principles investigations of O2 dissociation on low-coordinated Pd ensembles over stepped Au surfaces

    International Nuclear Information System (INIS)

    Yuan, D.W.; Liu, Z.R.; Xu, Y.

    2012-01-01

    The adsorption and dissociation of O 2 on Pd monomer or trimer incorporated into Au(322) and Au(321) surfaces are systematically investigated by first-principles calculations and nudged-elastic-band simulations. We found that the contiguous low-coordinated Pd ensembles alloyed into step edges of Au surfaces are required for O 2 dissociation with an enhanced adsorption energy (∼−1.00 eV). The dissociative barrier of O 2 is mainly related to the size of Pd ensembles, and the activation energy is about 1.00 eV on Pd trimers. However, the Pd monomer is less active for the adsorption and dissociation of O 2 . Additionally, the O spillover from Pd to Au sites only occurs at elevated temperature, and the diffusion processes are highly endothermic. The calculated results indicate that the Pd-modified Au step edge with a contiguous Pd ensemble is the reactive center for supplying atomic oxygen on Pd-doped Au catalysts. -- Highlights: ► Our results reveal the mechanism of O 2 dissociation on Pd-decorated stepped Au surfaces. ► The adsorption energy of O 2 is related to both coordination numbers and geometrical arrangements of Pd atoms alloyed into Au surface. ► The Pd-modified Au step with a contiguous Pd ensemble is the reactive center for O 2 dissociation. ► Our results are important for understanding the catalytic properties of Pd-modified nanoporous gold, especially for those catalytic reactions related to O 2 activation.

  2. Process and device for the excitation and selective dissociation by absorption of a laser light and application to isotopic enrichment

    International Nuclear Information System (INIS)

    Rigny, Paul.

    1975-01-01

    The description is given of a process for the excitation and selective dissociation by absorption of the monochromatic light emitted by a high power laser. The laser light at frequency ν 1 is beamed on to an isotopic mixture of gaseous molecules, some of these molecules presenting transitions, between two vibration levels corresponding to a given isotope, separated by an energy interval ΔE 1 =2h ν 1 , and the molecules of a given isotopic species are thus preferentially dissociated into several component parts [fr

  3. Measurement of bar pp single diffraction dissociation at √s =546 and 1800 GeV

    International Nuclear Information System (INIS)

    Abe, F.; Albrow, M.; Amidei, D.; Anway-Wiese, C.; Apollinari, G.; Atac, M.; Auchincloss, P.; Azzi, P.; Bacchetta, N.; Baden, A.R.; Badgett, W.; Bailey, M.W.; Bamberger, A.; de Barbaro, P.; Barbaro-Galtieri, A.; Barnes, V.E.; Barnett, B.A.; Bauer, G.; Baumann, T.; Bedeschi, F.; Behrends, S.; Belforte, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Benlloch, J.; Bensinger, J.; Beretvas, A.; Berge, J.P.; Bertolucci, S.; Biery, K.; Bhadra, S.; Binkley, M.; Bisello, D.; Blair, R.; Blocker, C.; Bodek, A.; Bolognesi, V.; Booth, A.W.; Boswell, C.; Brandenburg, G.; Brown, D.; Buckley-Geer, E.; Budd, H.S.; Busetto, G.; Byon-Wagner, A.; Byrum, K.L.; Campagnari, C.; Campbell, M.; Caner, A.; Carey, R.; Carithers, W.; Carlsmith, D.; Carroll, J.T.; Cashmore, R.; Castro, A.; Cen, Y.; Cervelli, F.; Chadwick, K.; Chapman, J.; Chapin, T.J.; Chiarelli, G.; Chinowsky, W.; Cihangir, S.; Clark, A.G.; Cobal, M.; Connor, D.; Contreras, M.; Cooper, J.; Cordelli, M.; Crane, D.; Cunningham, J.D.; Day, C.; DeJongh, F.; Dell'Agnello, S.; Dell'Orso, M.; Demortier, L.; Denby, B.; Derwent, P.F.; Devlin, T.; Dickson, M.; Drucker, R.B.; Dunn, A.; Einsweiler, K.; Elias, J.E.; Ely, R.; Eno, S.; Errede, S.; Etchegoyen, A.; Farhat, B.; Frautschi, M.; Feldman, G.J.; Flaugher, B.; Foster, G.W.; Franklin, M.; Freeman, J.; Fuess, T.; Fukui, Y.; Garfinkel, A.F.; Gauthier, A.; Geer, S.; Gerdes, D.W.; Giannetti, P.; Giokaris, N.; Giromini, P.; Gladney, L.; Gold, M.; Gonzalez, J.; Goulianos, K.; Grassmann, H.; Grieco, G.M.; Grindley, R.; Grosso-Pilcher, C.; Haber, C.; Hahn, S.R.; Handler, R.; Hara, K.; Harral, B.; Harris, R.M.; Hauger, S.A.; Hauser, J.; Hawk, C.; Hessing, T.; Hollebeek, R.; Holloway, L.; Hoelscher, A.; Hong, S.; Houk, G.; Hu, P.; Hubbard, B.; Huffman, B.T.; Hughes, R.; Hurst, P.; Huth, J.; Hylen, J.; Incagli, M.; Ino, T.; Iso, H.; Jessop, C.P.; Johnson, R.P.; Joshi, U.; Kadel, R.W.; Kamon, T.; Kanda, S.; Kardelis, D.A.; Karliner, I.; Kearns, E.; Keeble, L.; Kephart, R.; Kesten, P.

    1994-01-01

    We report a measurement of the diffraction dissociation differential cross section d 2 σ SD /dM 2 dt for bar pp→ bar pX at √s =546 and 1800 GeV, M 2 /s 2 . Our results are compared to theoretical predictions and to extrapolations from experimental results at lower energies

  4. Ab Initio Study of Hydration and Proton Dissociation in Ionomer Membranes

    International Nuclear Information System (INIS)

    Idupulapati, Nagesh B.; Devanathan, Ramaswami; Dupuis, Michel

    2010-01-01

    We present a comparative study of proton dissociation in various functional acidic units that are promising candidates as building blocks for polymeric electrolyte membranes. Minimum energy structures for four acidic moieties with clusters of 1-6 water molecules were determined using density functional theory at the B3LYP/6-311G** level starting from chemically rational initial configurations. The perfluoro sulfonyl imide acid group (CF3CF2SO2NHSO2CF3) was observed to be the strongest acid, due to the substantial electron withdrawing effect of both fluorocarbon groups. The hydrophilic functional group (CH3OC6H3OCH3C6H4SO3H) of sulfonated polyetherether ketone (SPEEK) membrane was found to be the strongest base with the acidic proton dissociation requiring the addition of six water molecules and the hydrated proton being more tightly bound to the conjugate base. Even though both perfluoro sulfonyl imides and sulfonic acids (hydrophilic functional groups for sulfonyl imide and Nafion ionomers respectively) required only three water molecules to exhibit spontaneous proton dissociation, the largest possible solvent-separated hydronium ion was attained only for the sulfonyl imide moiety. These results provide a scientific basis for understanding the improved conductivity of perfluorinated sulfonyl imide-based membranes relative to that of the widely-used Nafion membrane.

  5. An Examination of Dissociative Symptoms As They Relate To Indigenous Filipino Concepts

    Directory of Open Access Journals (Sweden)

    Heather J. Davediuk Gingrich

    2006-12-01

    Full Text Available In one phase of a larger study entitled Dissociation in a student sample in the Philippines (Gingrich, 2004, interviewees were asked to give their opinions about various scenarios involving dissociative symptoms, including whether they would regard specific dissociative experiences as normal or pathological.These college students were also requested to suggest indigenous terms for dissociative symptoms in Filipino languages. In order to provide a context for a discussion of these qualitative research findings, dissociation is defined, andplaced in its historical and cross-cultural context. A summary of how dissociative symptoms have generally been viewed within the Philippines is also included. The methodology used in the larger study is briefly outlined, while the procedures used to collect the data most relevant to the purposes ofthis article are more thoroughly described. Relevance of the findings for the social sciences is discussed, and recommendations for further research made.

  6. Dissociation mechanism of HNIW ions investigated by chemical ionization and electron impact mass spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rongjie; Xiao, Hemiao [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2006-04-15

    Chemical Ionization (CI) with Collision-Induced Dissociation (CID) spectroscopy and Electron Impacting (EI) with metastable Mass analyzed Ion Kinetic Energy (MIKE) spectroscopy have been applied to study ionic dissociations of Hexanitrohexaazaisowurtzitane (HNIW). Similarities and differences between EI/MIKE and CI/CID mass spectra of HNIW were analyzed. In EI mass spectra, the ions [HNIW-n NO{sub 2}]{sup +} (n=2-5), such as the ion at m/z 347, were less frequent (1-2% relative abundance), but in CI mass spectra, these ions were very abundant. For some ions of large molar mass from HNIW, their dissociations pathways from parent ions to daughter ions were built according to CID and MIKE spectra. Molecular ions of HNIW with a protonated nitro group at five-member ring seem more stable than at six-member ring. The HNIW ions losing five of six nitro groups are very stable based on CID spectra, which agrees with some research results for thermal decomposition of HNIW in literature. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  7. The dissociative subtype of posttraumatic stress disorder: rationale, clinical and neurobiological evidence, and implications.

    Science.gov (United States)

    Lanius, Ruth A; Brand, Bethany; Vermetten, Eric; Frewen, Paul A; Spiegel, David

    2012-08-01

    Clinical and neurobiological evidence for a dissociative subtype of posttraumatic stress disorder (PTSD) has recently been documented. A dissociative subtype of PTSD is being considered for inclusion in the forthcoming Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5) to address the symptoms of depersonalization and derealization found among a subset of patients with PTSD. This article reviews research related to the dissociative subtype including antecedent, concurrent, and predictive validators as well as the rationale for recommending the dissociative subtype. The relevant literature pertaining to the dissociative subtype of PTSD was reviewed. Latent class analyses point toward a specific subtype of PTSD consisting of symptoms of depersonalization and derealization in both veteran and civilian samples of PTSD. Compared to individuals with PTSD, those with the dissociative subtype of PTSD also exhibit a different pattern of neurobiological response to symptom provocation as well as a differential response to current cognitive behavioral treatment designed for PTSD. We recommend that consideration be given to adding a dissociative subtype of PTSD in the revision of the DSM. This facilitates more accurate analysis of different phenotypes of PTSD, assist in treatment planning that is informed by considering the degree of patients' dissociativity, will improve treatment outcome, and will lead to much-needed research about the prevalence, symptomatology, neurobiology, and treatment of individuals with the dissociative subtype of PTSD. © 2012 Wiley Periodicals, Inc.

  8. Dissociation of dilute immiscible copper alloy thin films

    International Nuclear Information System (INIS)

    Barmak, K.; Lucadamo, G. A.; Cabral, C. Jr.; Lavoie, C.; Harper, J. M. E.

    2000-01-01

    The dissociation behavior of dilute, immiscible Cu-alloy thin films is found to fall into three broad categories that correlate most closely with the form of the Cu-rich end of the binary alloy phase diagrams. Available thermodynamic and tracer diffusion data shed further light on alloy behavior. Eight alloying elements were selected for these studies, with five elements from groups 5 and 6, two from group 8, and one from group 11 of the periodic table. They are respectively V, Nb, Ta, Cr, Mo, Fe, Ru, and Ag. The progress of precipitation in approximately 500-nm-thick alloy films, containing 2.5-3.8 at. % solute, was followed with in situ resistance and stress measurements as well as with in situ synchrotron x-ray diffraction. In addition, texture analysis and transmission electron microscopy were used to investigate the evolution of microstructure and texture of Cu(Ta) and Cu(Ag). For all eight alloys, dissociation occurred upon heating, with the rejection of solute and evolution of microstructure often occurring in multiple steps that range over several hundred degrees between approximately 100 and 900 degree sign C. However, in most cases, substantial reductions in resistivity of the films took place below 400 degree sign C, at temperatures of interest to copper metallization schemes for silicon chip technology. (c) 2000 American Institute of Physics

  9. Methane dissociation on the steps and terraces of Pt(211) resolved by quantum state and impact site

    Science.gov (United States)

    Chadwick, Helen; Guo, Han; Gutiérrez-González, Ana; Menzel, Jan Paul; Jackson, Bret; Beck, Rainer D.

    2018-01-01

    Methane dissociation on the step and terrace sites of a Pt(211) single crystal was studied by reflection absorption infrared spectroscopy (RAIRS) at a surface temperature of 120 K. The C—H stretch RAIRS signal of the chemisorbed methyl product species was used to distinguish between adsorption on step and terrace sites allowing methyl uptake to be monitored as a function of incident kinetic energy for both sites. Our results indicate a direct dissociation mechanism on both sites with higher reactivity on steps than on terraces consistent with a difference in an activation barrier height of at least 30 kJ/mol. State-specific preparation of incident CH4 with one quantum of antisymmetric (ν3) stretch vibration further increases the CH4 reactivity enabling comparison between translational and vibrational activation on both steps and terraces. The reaction is modeled with first principles quantum theory that accurately describes dissociative chemisorption at different sites on the surface.

  10. The Remains of the Day in Dissociative Amnesia

    Directory of Open Access Journals (Sweden)

    Angelica Staniloiu

    2012-04-01

    Full Text Available Memory is not a unity, but is divided along a content axis and a time axis, respectively. Along the content dimension, five long-term memory systems are described, according to their hierarchical ontogenetic and phylogenetic organization. These memory systems are assumed to be accompanied by different levels of consciousness. While encoding is based on a hierarchical arrangement of memory systems from procedural to episodic-autobiographical memory, retrieval allows independence in the sense that no matter how information is encoded, it can be retrieved in any memory system. Thus, we illustrate the relations between various long-term memory systems by reviewing the spectrum of abnormalities in mnemonic processing that may arise in the dissociative amnesia—a condition that is usually characterized by a retrieval blockade of episodic-autobiographical memories and occurs in the context of psychological trauma, without evidence of brain damage on conventional structural imaging. Furthermore, we comment on the functions of implicit memories in guiding and even adaptively molding the behavior of patients with dissociative amnesia and preserving, in the absence of autonoetic consciousness, the so-called “internal coherence of life”.

  11. Dissociating the two faces of selective memory retrieval.

    Science.gov (United States)

    Dobler, Ina M; Bäuml, Karl-Heinz T

    2012-07-01

    Research in the past four decades has repeatedly shown that selective retrieval of some (non-target) memories can impair subsequent retrieval of other (target) information, a finding known as retrieval-induced forgetting. More recently, however, there is evidence that selective retrieval can both impair and enhance recall of related memories (K-H. T. Bäuml & Samenieh, 2010). To identify possible experimental dissociations between the detrimental and the beneficial effects of memory retrieval, we examined retrieval dynamics in listwise directed forgetting, varying the delay between preceding non-target and subsequent target recall. When target recall immediately followed non-target recall, we replicated the prior work and found detrimental effects of memory retrieval on to-be-remembered items but beneficial effects on to-be-forgotten items. In contrast, when a delay was introduced between non-target and target recall, the detrimental effects were present but the beneficial effects were absent. The results demonstrate a first experimental dissociation between the two effects of memory retrieval. They are consistent with a recent two-factor account of the two faces of selective memory retrieval.

  12. Simulating the effect of hydrate dissociation on wellhead stability during oil and gas development in deepwater

    Science.gov (United States)

    Li, Qingchao; Cheng, Yuanfang; Zhang, Huaiwen; Yan, Chuanliang; Liu, Yuwen

    2018-02-01

    It is well known that methane hydrate has been identified as an alternative resource due to its massive reserves and clean property. However, hydrate dissociation during oil and gas development (OGD) process in deep water can affect the stability of subsea equipment and formation. Currently, there is a serious lack of studies over quantitative assessment on the effects of hydrate dissociation on wellhead stability. In order to solve this problem, ABAQUS finite element software was used to develop a model and to evaluate the behavior of wellhead caused by hydrate dissociation. The factors that affect the wellhead stability include dissociation range, depth of hydrate formation and mechanical properties of dissociated hydrate region. Based on these, series of simulations were carried out to determine the wellhead displacement. The results revealed that, continuous dissociation of hydrate in homogeneous and isotropic formations can causes the non-linear increment in vertical displacement of wellhead. The displacement of wellhead showed good agreement with the settlement of overlying formations under the same conditions. In addition, the shallower and thicker hydrate formation can aggravate the influence of hydrate dissociation on the wellhead stability. Further, it was observed that with the declining elastic modulus and Poisson's ratio, the wellhead displacement increases. Hence, these findings not only confirm the effect of hydrate dissociation on the wellhead stability, but also lend support to the actions, such as cooling the drilling fluid, which can reduce the hydrate dissociation range and further make deepwater operations safer and more efficient.

  13. A functional dissociation of conflict processing within anterior cingulate cortex.

    Science.gov (United States)

    Kim, Chobok; Kroger, James K; Kim, Jeounghoon

    2011-02-01

    Goal-directed behavior requires cognitive control to regulate the occurrence of conflict. The dorsal anterior cingulate cortex (dACC) has been suggested in detecting response conflict during various conflict tasks. Recent findings, however, have indicated not only that two distinct subregions of dACC are involved in conflict processing but also that the conflict occurs at both perceptual and response levels. In this study, we sought to examine whether perceptual and response conflicts are functionally dissociated in dACC. Thirteen healthy subjects performed a version of the Stroop task during functional magnetic resonance imaging (fMRI) scanning. We identified a functional dissociation of the caudal dACC (cdACC) and the rostral dACC (rdACC) in their responses to different sources of conflict. The cdACC was selectively engaged in perceptual conflict whereas the rdACC was more active in response conflict. Further, the dorsolateral prefrontal cortex (DLPFC) was coactivated not with cdACC but with rdACC. We suggest that cdACC plays an important role in regulative processing of perceptual conflict whereas rdACC is involved in detecting response conflict. Copyright © 2010 Wiley-Liss, Inc.

  14. Electron beam induced deposition of silacyclohexane and dichlorosilacyclohexane: the role of dissociative ionization and dissociative electron attachment in the deposition process

    Directory of Open Access Journals (Sweden)

    Ragesh Kumar T P

    2017-11-01

    Full Text Available We present first experiments on electron beam induced deposition of silacyclohexane (SCH and dichlorosilacyclohexane (DCSCH under a focused high-energy electron beam (FEBID. We compare the deposition dynamics observed when growing pillars of high aspect ratio from these compounds and we compare the proximity effect observed for these compounds. The two precursors show similar behaviour with regards to fragmentation through dissociative ionization in the gas phase under single-collision conditions. However, while DCSCH shows appreciable cross sections with regards to dissociative electron attachment, SCH is inert with respect to this process. We discuss our deposition experiments in context of the efficiency of these different electron-induced fragmentation processes. With regards to the deposition dynamics, we observe a substantially faster growth from DCSCH and a higher saturation diameter when growing pillars with high aspect ratio. However, both compounds show similar behaviour with regards to the proximity effect. With regards to the composition of the deposits, we observe that the C/Si ratio is similar for both compounds and in both cases close to the initial molecular stoichiometry. The oxygen content in the DCSCH deposits is about double that of the SCH deposits. Only marginal chlorine is observed in the deposits of from DCSCH. We discuss these observations in context of potential approaches for Si deposition.

  15. Psychobiological characteristics of dissociative identity disorder: a symptom provocation study.

    Science.gov (United States)

    Reinders, A A T Simone; Nijenhuis, Ellert R S; Quak, Jacqueline; Korf, Jakob; Haaksma, Jaap; Paans, Anne M J; Willemsen, Antoon T M; den Boer, Johan A

    2006-10-01

    Dissociative identity disorder (DID) patients function as two or more identities or dissociative identity states (DIS), categorized as 'neutral identity states' (NIS) and 'traumatic identity states' (TIS). NIS inhibit access to traumatic memories thereby enabling daily life functioning. TIS have access and responses to these memories. We tested whether these DIS show different psychobiological reactions to trauma-related memory. A symptom provocation paradigm with 11 DID patients was used in a two-by-two factorial design setting. Both NIS and TIS were exposed to a neutral and a trauma-related memory script. Three psychobiological parameters were tested: subjective ratings (emotional and sensori-motor), cardiovascular responses (heart rate, blood pressure, heart rate variability) and regional cerebral blood flow as determined with H(2)(15)O positron emission tomography. Psychobiological differences were found for the different DIS. Subjective and cardiovascular reactions revealed significant main and interactions effects. Regional cerebral blood flow data revealed different neural networks to be associated with different processing of the neutral and trauma-related memory script by NIS and TIS. Patients with DID encompass at least two different DIS. These identities involve different subjective reactions, cardiovascular responses and cerebral activation patterns to a trauma-related memory script.

  16. Mathematical modelling of nonstationary processes in a regenerator with dissociating coolant at supercritical parameters

    International Nuclear Information System (INIS)

    Tashchilova, Eh.M.; Sharovarov, G.A.

    1985-01-01

    The mathematical model of nonstationary processes in heat exchangers with dissociating coolant at supercritical parameters is given. Its dimensionless criteria are deveped. The effect of NPP regenerator parameters on criteria variation is determined. The proceeding nonstationary processes are estimated qualitatively using the dimensionless parameters. Dynamics of the processes in heat exchangers is described by the energy, mass and moment-of-momentum equations for heating and heated medium taking into account heat accumulation in the heat-transfer wall and distribution of parameters along the length of a heat exchanger

  17. Dissociative multiple ionization of diatomic molecules by extreme-ultraviolet free-electron-laser pulses

    DEFF Research Database (Denmark)

    Madsen, Lars Bojer; Leth, Henriette Astrup

    2011-01-01

    Nuclear dynamics in dissociative multiple ionization processes of diatomic molecules exposed to extreme-ultraviolet free-electron-laser pulses is studied theoretically using the Monte Carlo wave packet approach. By simulated detection of the emitted electrons, the model reduces a full propagation...... of the system to propagations of the nuclear wave packet in one specific electronic charge state at a time. Suggested ionization channels can be examined, and kinetic energy release spectra for the nuclei can be calculated and compared with experiments. Double ionization of O2 is studied as an example, and good...

  18. Differential dissociation micromethod for the investigation of binding of metandrostenolone (Nerobol) to plasma proteins

    International Nuclear Information System (INIS)

    Bojadzsieva, Milka; Kocsar, Laszlo; Kremmer, Tibor

    1985-01-01

    A micromethod was developed to determine the binding of anabolic streoids to plasma proteins. The new procedure combines precipitation with ammonium sulphate and differential dissociation. The binding parameters (association constant, specific binding capacity) are calculated on the basis of dissociation curves of sup(3)H-metandrostenolone from the precipitated sexual binding globuline. (L.E.)

  19. Differential dissociation micromethod for the investigation of binding of metandrostenolone (Nerobol) to plasma proteins

    Energy Technology Data Exchange (ETDEWEB)

    Bojadzsieva, M.; Kocsar, L. (Orszagos Frederic Joliot-Curie Sugarbiologiai es Sugaregeszseguegyi Kutato Intezet, Budapest (Hungary)); Kremmer, T. (Orszagos Onkologiai Intezet, Budapest (Hungary))

    1985-01-01

    A micromethod was developed to determine the binding of anabolic steroids to plasma proteins. The new procedure combines precipitation with ammonium sulphate and differential dissociation. The binding parameters (association constant, specific binding capacity) are calculated on the basis of dissociation curves of sup(3)H-metandrostenolone from the precipitated sexual binding globuline.

  20. Many-body formation and dissociation of a dipolar chain crystal

    International Nuclear Information System (INIS)

    You, Jhih-Shih; Wang, Daw-Wei

    2014-01-01

    We propose an experimental scheme to effectively assemble chains of dipolar gases with a uniform length in a multi-layer system. The obtained dipolar chains can form a chain crystal with the system temperature easily controlled by the initial lattice potential and the external field strength during processing. When the density of chains increases, we further observe a second order quantum phase transition for the chain crystal to be dissociated toward layers of 2D crystal, where the quantum fluctuation dominates the classical energy and the compressibility diverges at the phase boundary. The experimental implication of such a dipolar chain crystal and its quantum phase transition is also discussed. (paper)

  1. Model of the dissociative recombination of molecular ions based on the statistical 'phase-space theory'

    International Nuclear Information System (INIS)

    Foltin, M.; Lukac, P.; Morva, I.; Foltin, V.

    2004-01-01

    In the paper the statistical 'phase-space theory' extended for chemical reactions and for dissociative recombination of polyatomic ions is applied to the indirect and direct dissociative recombination of diatomic ions with electrons. Numerical calculations are made for molecular neon ion. The good agreement is obtained with experimental results (Authors)

  2. Insights into the effect of coverage on CO adsorption and dissociation over Rh(1 0 0) surface: A theoretical study

    International Nuclear Information System (INIS)

    Zhao, Xiaojun; Zhang, Riguang; Ling, Lixia; Wang, Baojun

    2014-01-01

    Graphical abstract: - Highlights: • The adsorption energies gradually decrease with the increasing of CO coverage on Rh(1 0 0). • CO reaches the saturated adsorption with the coverage of 12/12 ML on Rh(1 0 0). • Both CO desorption and dissociation co-exist at the coverage less than or equal to 2/12 ML. • Only molecule CO adsorption is favored at the coverage greater than or equal to 3/12 ML. • Only molecule CO adsorption form exists in syngas conversion on Rh catalyst. - Abstract: The adsorption, dissociation and desorption of CO at different coverage over Rh(1 0 0) surface have been systematically investigated using density functional theory method together with the periodic slab model. Our results show that at the coverage less than or equal to 4/12 ML, CO favored the most stable bridge site adsorption, and the adsorption energies of CO have little difference; while at the coverage greater than or equal to 5/12 ML, the lateral repulsive interaction begins to affect the adsorption structures and the corresponding adsorption energies of adsorbed CO molecules, and the interaction will be stronger with the increasing of CO coverage, which leads to CO migration over Rh(1 0 0) surface when CO coverage is greater than or equal to 10/12 ML. The adsorption energies of these CO molecules will decrease successively until the saturated adsorption with the CO coverage of 12/12 ML. Further calculations on CO dissociation indicate that when CO coverage is greater than or equal to 3/12 ML, the dissociation of adsorbed CO molecules will be unfavorable both kinetically and thermodynamically, suggesting that only molecule CO adsorption are favored. Considering the catalytic activity of Rh(1 0 0) surface toward CO dissociation and the higher CO coverage under the continuous supply of CO in syngas conversion, it is to be expected that only molecule CO adsorption exist on Rh catalyst

  3. Extension of CE/SE method to non-equilibrium dissociating flows

    KAUST Repository

    Wen, C.Y.

    2017-12-08

    In this study, the hypersonic non-equilibrium flows over rounded nose geometries are numerically investigated by a robust conservation element and solution element (CE/SE) code, which is based on hybrid meshes consisting of triangular and quadrilateral elements. The dissociating and recombination chemical reactions as well as the vibrational energy relaxation are taken into account. The stiff source terms are solved by an implicit trapezoidal method of integration. Comparison with laboratory and numerical cases are provided to demonstrate the accuracy and reliability of the present CE/SE code in simulating hypersonic non-equilibrium flows.

  4. Dissociation of water and Acetic acid on PbS from first principles

    Science.gov (United States)

    Satta, Alessandra; Ruggerone, Paolo; de Giudici, Giovanni

    2008-03-01

    The adsorption of complex molecules at mineral surfaces are crucial ingredients for understanding the mechanisms that rule the interaction between minerals and the biosphere and for predicting both the stability and the reactivity of minerals. The present work focuses mainly on the early stages of different adsorption reactions occurring at both the cleavage surface and a high-index vicinal surface of galena (PbS). We have studied the dissociation mechanism of water and acetic acid on the galena surfaces by means of ab initio calculations within the framework of the density functional theory in the generalized gradient approximation and of pseudopotential approach. The calculated adsorption energies of the molecules indicate the stepped surface as the most reactive, as expected. The free energy surface during the reaction process has been explored via metadynamics[1]. The optimized configurations of both reactants and products obtained, were then used to accurately calculate the dissociation energy via the Nudge Elastic Band method[2]. [1] A. Laio and M. Parrinello, PNAS 99, 12562 (2002). [2] G. Mills and H. Jonsson, Phys. Rev. Lett. 72, 1124 (1994).

  5. Thought beyond language: neural dissociation of algebra and natural language.

    Science.gov (United States)

    Monti, Martin M; Parsons, Lawrence M; Osherson, Daniel N

    2012-08-01

    A central question in cognitive science is whether natural language provides combinatorial operations that are essential to diverse domains of thought. In the study reported here, we addressed this issue by examining the role of linguistic mechanisms in forging the hierarchical structures of algebra. In a 3-T functional MRI experiment, we showed that processing of the syntax-like operations of algebra does not rely on the neural mechanisms of natural language. Our findings indicate that processing the syntax of language elicits the known substrate of linguistic competence, whereas algebraic operations recruit bilateral parietal brain regions previously implicated in the representation of magnitude. This double dissociation argues against the view that language provides the structure of thought across all cognitive domains.

  6. Isotope effects in photo dissociation of ozone with visible light

    Science.gov (United States)

    Früchtl, Marion; Janssen, Christof; Röckmann, Thomas

    2014-05-01

    Ozone (O3) plays a key role for many chemical oxidation processes in the Earth's atmosphere. In these chemical reactions, ozone can transfer oxygen to other trace gases. This is particularly interesting, since O3 has a very peculiar isotope composition. Following the mass dependent fractionation equation δ17O = 0.52 * δ18O, most fractionation processes depend directly on mass. However, O3 shows an offset to the mass dependent fractionation line. Processes, which show such anomalies, are termed mass independent fractionations (MIF). A very well studied example for a chemical reaction that leads to mass independent fractionation is the O3 formation reaction. To what degree O3 destruction reactions need to be considered in order to understand the isotope composition of atmospheric O3 is still not fully understood and an open question within scientific community. We set up new experiments to investigate the isotope effect resulting from photo dissociation of O3 in the Chappuis band (R1). Initial O3 is produced by an electric discharge. After photolysis O3 is collected in a cold trap at the triple point temperature of nitrogen (63K). O3 is then converted to O2 in order to measure the oxygen isotopes of O3 using isotope ratio mass spectrometry. To isolate O3 photo dissociation (R1) from O3 decomposition (R2) and secondary O3 formation (R3), we use varying amounts of carbon monoxide (CO) as O atom quencher (R4). In this way we suppress the O + O3 reaction (R3) and determine the isotope fractionation in R1 and R2 separately. We present first results on the isotope effects in O3 photo dissociation with visible light in the presence of different bath gases. Results are interpreted based on chemical kinetics modeling. (R1) O3 + hυ → O (3P) + O2 (R2) O3 + O (3P) → 2 O2 (R3) O + O2 + M → O3 + M (R4) O (3P) + CO + M → CO2 + M

  7. Negative ion formation in dissociative electron attachment to selected halogen derivatives of propane

    Science.gov (United States)

    Barszczewska, W.; Kocísek, J.; Skalný, J.; Matejcík, V.; Matejcík, S.

    2008-11-01

    Dissociative electron attachment (DEA) to halogenated derivatives of propane: 1-bromo-3-chloropropane, 2-bromo-1-chloropropane, 3-bromo-1,1,1-trichloropropane and 1,3-dibromo-1,1-difluoropropane was studied in the gas phase at ambient temperature using a high resolution crossed electron/molecule beams technique. The negative ions formed via DEA reaction were identified using mass spectrometric technique and the anion yields were measured in the electron energy range from 0 to 10 eV. The absolute partial cross sections for DEA to the molecules were estimated using the relative flow technique.

  8. Adsorption and dissociation of Cl{sub 2} molecule on ZnO nanocluster

    Energy Technology Data Exchange (ETDEWEB)

    Beheshtian, Javad [Department of Chemistry, Shahid Rajaee Teacher Training University, P.O. Box: 16875-163, Tehran (Iran, Islamic Republic of); Peyghan, Ali Ahmadi, E-mail: ahmadi.iau@gmail.com [Young Researchers Club, Islamic Azad University, Islamshahr Branch, Tehran (Iran, Islamic Republic of); Bagheri, Zargham [Physics group, Science department, Islamic Azad University, Islamshahr Branch, P.O. Box: 33135-369, Islamshahr, Tehran (Iran, Islamic Republic of)

    2012-08-01

    Adsorption of chlorine molecule (Cl{sub 2}) on the Zn{sub 12}O{sub 12} nano-cage has been analyzed using density functional theory. It has been shown that the Cl{sub 2} molecule is strongly adsorbed on the cluster via two mechanisms including chemisorption and dissociation with Gibbs free energy changes in the range of -0.36 to -0.92 eV at 298 K and 1 atm. These processes also significantly change the electronic properties of cluster by decreasing its HOMO/LUMO energy gap and increasing the work function. The Fermi level shifts towards lower energies upon the interactions between Cl{sub 2} and the cluster, resulting in raised potential barrier of the electron emission for the cluster and hence avoiding the field emission. The Zn{sub 12}O{sub 12} cluster is transformed to a p-type semiconductor substance upon the Cl{sub 2} dissociation. We believe that the obtained results may be helpful in several fields of study such as sensors, catalysts, and field emission investigations.

  9. Algorithm for Calculating the Dissociation Constants of Ampholytes in Nonbuffer Systems

    Science.gov (United States)

    Lysova, S. S.; Skripnikova, T. A.; Zevatskii, Yu. E.

    2018-05-01

    An algorithm for calculating the dissociation constants of ampholytes in aqueous solutions is developed on the basis of spectrophotometric data in the UV and visible ranges without pH measurements of a medium and without buffer solutions. The proposed algorithm has been experimentally tested for five ampholytes of different strengths. The relative error of measuring dissociation constants is less than 5%.

  10. Dissociative Experiences, Creative Imagination, and Artistic Production in Students of Fine Arts

    Science.gov (United States)

    Perez-Fabello, Maria Jose; Campos, Alfredo

    2011-01-01

    The current research was designed to assess the influence of dissociative experiences and creative imagination on the artistic production of Fine Arts students of the University of Vigo (Spain). The sample consisted of 81 students who were administered the Creative Imagination Scale and The Dissociative Experiences Scale. To measure artistic…

  11. Dissociation in the phenomenological perspective (in athletes and representatives of extreme careers

    Directory of Open Access Journals (Sweden)

    Anastasia S. Vlasik

    2015-09-01

    Full Text Available This paper attempts to analyze dissociation from the perspective of phenomenology as experience of persons engaged in activities related to high stress (physical and/ or psychological. Dissociation is usually correlated with the so-called reaction fading in life-threatening situations, which along with the reactions of “fight or flight” reveal both in humans and the representatives of the animal world (“fight, flight or freeze”. However, unlike animals humans are often able to act purposefully in dissociative states, or randomly enter them. Specific features and diversity of manifestations of dissociation in humans are determined by the linguistic nature of human consciousness, which is logical to appeal to the philosophers of the phenomenological direction within which consciousness is the subject matter of their research. Based on the concept of Henri Bergson and Gilles Deleuze various manifestations of dissociation are detected: from the grave symptoms of PTSD (the so-called invasion of symptoms to controlled arbitrarily selected dissociative strategies for athletes. Dissociative experiences by experts of extreme careers are considered: law enforcement officers who participated in missions in «hot spots», and EMERCOM psychologists. Dissociation mechanism in terms of phenomenology is defined. The development and application of adequate diagnostic tools, psychological work with the athletes to regulate the focus of attention during the competition is supposed to contribute to the achievement of a high sports results.

  12. Dissociation of Procedural and Working Memory in Pigeons (Columba livia

    Directory of Open Access Journals (Sweden)

    Walter T. Herbranson

    2016-07-01

    Full Text Available A new method was developed to concurrently investigate procedural memory and working memory in pigeons. Pigeons performed a sequence of keypecks across 3 response keys in a serial response task, with periodic choice probes for the location of a recently produced response. Procedural memory was operationally defined as decreasing response times to predictable cues in the sequence. Working memory was reflected by accurate responses to the choice probes. Changing the sequence of required keypecks to a random sequence interfered with procedural memory in the form of slowed response times, but did not prevent pigeons from effectively using working memory to remember specific cue locations. Conversely, changing exposure duration of to a cue location influenced working memory but had no effect on procedural memory. Double dissociations such as this have supported the multiple systems approach to the study of memory in cognitive psychology and neuroscience, and they encourage a similar approach in comparative psychology.

  13. Multistage audiovisual integration of speech: dissociating identification and detection.

    Science.gov (United States)

    Eskelund, Kasper; Tuomainen, Jyrki; Andersen, Tobias S

    2011-02-01

    Speech perception integrates auditory and visual information. This is evidenced by the McGurk illusion where seeing the talking face influences the auditory phonetic percept and by the audiovisual detection advantage where seeing the talking face influences the detectability of the acoustic speech signal. Here, we show that identification of phonetic content and detection can be dissociated as speech-specific and non-specific audiovisual integration effects. To this end, we employed synthetically modified stimuli, sine wave speech (SWS), which is an impoverished speech signal that only observers informed of its speech-like nature recognize as speech. While the McGurk illusion only occurred for informed observers, the audiovisual detection advantage occurred for naïve observers as well. This finding supports a multistage account of audiovisual integration of speech in which the many attributes of the audiovisual speech signal are integrated by separate integration processes.

  14. Semiclassical Calculation of Reaction Rate Constants for Homolytical Dissociations

    Science.gov (United States)

    Cardelino, Beatriz H.

    2002-01-01

    There is growing interest in extending organometallic chemical vapor deposition (OMCVD) to III-V materials that exhibit large thermal decomposition at their optimum growth temperature, such as indium nitride. The group III nitrides are candidate materials for light-emitting diodes and semiconductor lasers operating into the blue and ultraviolet regions. To overcome decomposition of the deposited compound, the reaction must be conducted at high pressures, which causes problems of uniformity. Microgravity may provide the venue for maintaining conditions of laminar flow under high pressure. Since the selection of optimized parameters becomes crucial when performing experiments in microgravity, efforts are presently geared to the development of computational OMCVD models that will couple the reactor fluid dynamics with its chemical kinetics. In the present study, we developed a method to calculate reaction rate constants for the homolytic dissociation of III-V compounds for modeling OMCVD. The method is validated by comparing calculations with experimental reaction rate constants.

  15. Dissociable endogenous and exogenous attention in disorders of consciousness.

    Science.gov (United States)

    Chennu, Srivas; Finoia, Paola; Kamau, Evelyn; Monti, Martin M; Allanson, Judith; Pickard, John D; Owen, Adrian M; Bekinschtein, Tristan A

    2013-01-01

    Recent research suggests that despite the seeming inability of patients in vegetative and minimally conscious states to generate consistent behaviour, some might possess covert awareness detectable with functional neuroimaging. These findings motivate further research into the cognitive mechanisms that might support the existence of consciousness in these states of profound neurological dysfunction. One of the key questions in this regard relates to the nature and capabilities of attention in patients, known to be related to but distinct from consciousness. Previous assays of the electroencephalographic P300 marker of attention have demonstrated its presence and potential clinical value. Here we analysed data from 21 patients and 8 healthy volunteers collected during an experimental task designed to engender exogenous or endogenous attention, indexed by the P3a and P3b components, respectively, in response to a pair of word stimuli presented amongst distractors. Remarkably, we found that the early, bottom-up P3a and the late, top-down P3b could in fact be dissociated in a patient who fitted the behavioural criteria for the vegetative state. In juxtaposition with healthy volunteers, the patient's responses suggested the presence of a relatively high level of attentional abilities despite the absence of any behavioural indications thereof. Furthermore, we found independent evidence of covert command following in the patient, as measured by functional neuroimaging during tennis imagery. Three other minimally conscious patients evidenced non-discriminatory bottom-up orienting, but no top-down engagement of selective attentional control. Our findings present a persuasive case for dissociable attentional processing in behaviourally unresponsive patients, adding to our understanding of the possible levels and applications of consequent conscious awareness.

  16. Dissociation constants of phosphoric acid in dimethylformamide-water mixtures at 298.15 K

    Science.gov (United States)

    Safonova, L. P.; Fadeeva, Yu. A.; Pryakhin, A. A.

    2009-10-01

    The dissociation constants of phosphoric acid (p K 1 and p K 2) in water-dimethylformamide (DMFA) mixtures (0-0.65 mole fractions of DMFA) were determined at 298.15 K by potentiometric titration. The extrapolation of these data to pure DMFA and the comparative calculation method were used to estimate the dissociation constants of the acid in DMFA.

  17. Multistage audiovisual integration of speech: dissociating identification and detection

    DEFF Research Database (Denmark)

    Eskelund, Kasper; Tuomainen, Jyrki; Andersen, Tobias

    2011-01-01

    Speech perception integrates auditory and visual information. This is evidenced by the McGurk illusion where seeing the talking face influences the auditory phonetic percept and by the audiovisual detection advantage where seeing the talking face influences the detectability of the acoustic speech...... signal. Here we show that identification of phonetic content and detection can be dissociated as speech-specific and non-specific audiovisual integration effects. To this end, we employed synthetically modified stimuli, sine wave speech (SWS), which is an impoverished speech signal that only observers...... informed of its speech-like nature recognize as speech. While the McGurk illusion only occurred for informed observers the audiovisual detection advantage occurred for naïve observers as well. This finding supports a multi-stage account of audiovisual integration of speech in which the many attributes...

  18. The Importance of the Dissociation Rate in Ion Channel Blocking

    Directory of Open Access Journals (Sweden)

    Hugo Zeberg

    2018-02-01

    Full Text Available Understanding the relationships between the rates and dynamics of current wave forms under voltage clamp conditions is essential for understanding phenomena such as state-dependence and use-dependence, which are fundamental for the action of drugs used as anti-epileptics, anti-arrhythmics, and anesthetics. In the present study, we mathematically analyze models of blocking mechanisms. In previous experimental studies of potassium channels we have shown that the effect of local anesthetics can be explained by binding to channels in the open state. We therefore here examine models that describe the effect of a blocking drug that binds to a non-inactivating channel in its open state. Such binding induces an inactivation-like current decay at higher potential steps. The amplitude of the induced peak depends on voltage and concentration of blocking drug. In the present study, using analytical methods, we (i derive a criterion for the existence of a peak in the open probability time evolution for a model with an arbitrary number of closed states, (ii derive formula for the relative height of the peak amplitude, and (iii determine the voltage dependence of the relative peak height. Two findings are apparent: (1 the dissociation (unbinding rate constant is important for the existence of a peak in the current waveform, while the association (binding rate constant is not, and (2 for a peak to exist it suffices that the dissociation rate must be smaller than the absolute value of all eigenvalues to the kinetic matrix describing the model.

  19. Obesity and dissociable forms of impulsivity in young adults.

    Science.gov (United States)

    Chamberlain, Samuel R; Derbyshire, Katherine L; Leppink, Eric; Grant, Jon E

    2015-10-01

    Obesity is one of the leading causes of preventable morbidity and mortality, and young people are increasingly affected. The aim of this study was to examine relationships between obesity and dissociable forms of impulsivity in young adults. A group of young adults (511) was recruited from city areas in the United States using media advertisements. These young adults were administered careful and extensive clinical and neurocognitive assessment in order to quantify different aspects of impulsivity (behavioral/phenomenological-, cognitive-, and personality-related measures). Associations between obesity and impulsivity were explored using multivariate analysis of variance and discriminant function analysis. 10.8% of the sample was obese, and 21.5% was overweight. Compared to controls, subjects with obesity showed significantly elevated rates of maladaptive gambling behaviors, monetary amounts lost to gambling, nicotine consumption, impulsive action (prolonged stop-signal reaction times in the Stop-Signal Test), and impulsive decision-making (reduced modulation of behavior as a function of risk in the Cambridge Gamble Test). Even accounting for potential confounding variables, obesity was significantly predicted by female gender, older age, more maladaptive gambling behaviors, and worse inhibitory control (stop-signal reaction times). Obesity is associated with several dissociable forms of impulsivity in young people, especially gambling and impulse dyscontrol. Family doctors should screen for gambling problems in obese young adults. Successful treatment of nicotine dependence in young obese people is likely to require intensive weight management support. Neuropsychological deficits relating to impulsivity occur in obese people in early adulthood, and may represent vulnerability markers rather than being due to chronic untoward metabolic effects on brain function.

  20. Posttraumatic stress symptoms, dissociation, and alexithymia in an Italian sample of flood victims

    Directory of Open Access Journals (Sweden)

    Craparo G

    2014-11-01

    Full Text Available Giuseppe Craparo,1 Alessio Gori,2 Elvira Mazzola,1 Irene Petruccelli,1 Monica Pellerone,1 Giuseppe Rotondo3 1Faculty of Human and Social Sciences, Kore University of Enna, Enna, Italy; 2Department of Psychology, University of Florence, Florence, Italy; 3Department of Psychology, Unit of Psychotraumatology, San Raffaele Giglio Hospital of Cefalù, Cefalù, Italy Background: Several studies have demonstrated a significant association between dissociation and posttraumatic symptoms. A dissociative reaction during a traumatic event may seem to predict the later development of posttraumatic stress symptoms. Moreover, several researchers also observed an alexithymic condition in a variety of traumatized samples.Methods: A total of 287 flood victims (men =159, 55.4%; women =128, 44.6% with an age range of 17–21 years (mean =18.33; standard deviation =0.68 completed the following: Impact of Event Scale–Revised, Dissociative Experiences Scale II, Twenty-Item Toronto Alexithymia Scale, and Peritraumatic Dissociative Experiences Questionnaire.Results: We found significant correlations among all variables. Linear regression showed that peritraumatic dissociation plays a mediator role between alexithymia, dissociation, and posttraumatic stress symptoms.Conclusion: Our results seem to confirm the significant roles of both dissociation and alexithymia for the development of posttraumatic symptoms. Keywords: peritraumatic dissociation, posttraumatic symptoms, PTSD

  1. Influence of cell dissociation procedures on the tumorigenicity of Simian Virus 40 transformed fibroblasts

    International Nuclear Information System (INIS)

    Tenforde, T.S.; Risius, J.; Beckmann, A.; Tobias, C.A.; Gurney, E.

    1975-11-01

    Mouse fibroblasts transformed by Simian Virus 40 (SV40) were examined for tumor forming ability in syngeneic BALB/c mice following dissociation from tissue culture dishes by two procedures. A significantly greater in vivo proliferative capacity was observed for cells dissociated by the tryspin-EDTA procedure, with the injected cell dose for tumor production in 50 percent of recipient mice (the TPD 50 ) being 16-fold lower than the TPD 50 for cells dissociated by the EDTA procedure. Host immunosuppression with 300 rad whole-body γ irradiation led to a significant 7-fold decrease in the TPD 50 for cells dissociated by the EDTA procedure, while no significant decrease in TPD 50 was observed for cells dissociated by the tryspin-EDTA procedure

  2. Diffraction dissociation at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Jenkovszky, Laszlo [Bogolyubov Institute for Theoretical Physics (BITP), Ukrainian National Academy of Sciences 14-b, Metrolohichna str., Kiev, 03680, Ukraine and Wigner Research Centre for Physics, Hungarian Academy of Sciences 1525 Budapest, POB 49 (Hungary); Orava, Risto [Institute of Physics, Division of Elementary Particle Physics, P.O. Box 64 (Gustaf Haellstroeminkatu 2a), FI-00014 University of Helsinki, Finland and CERN, CH-1211 Geneva 23 (Switzerland); Salii, Andrii [Bogolyubov Institute for Theoretical Physics (BITP), Ukrainian National Academy of Sciences 14-b, Metrolohichna str., Kiev, 03680 (Ukraine)

    2013-04-15

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  3. Diffraction dissociation at the LHC

    International Nuclear Information System (INIS)

    Jenkovszky, László; Orava, Risto; Salii, Andrii

    2013-01-01

    We report on recent calculations of low missing mass single (SD) and double (DD) diffractive dissociation at LHC energies. The calculations are based on a dual-Regge model, dominated by a single Pomeron exchange. The diffractively excited states lie on the nucleon trajectory N*, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single-and double diffraction dissociation in the kinematical range of present and future LHC measurements are given.

  4. Dissociative excitation of lithium atom in electron collisions with LiBr molecules

    International Nuclear Information System (INIS)

    Smirnov, Yu.M.

    1998-01-01

    Effective cross sections of the lithium atom dissociative excitation in electron collisions with the LiBr molecules are measured. The measurement error equals 5-12%. The optical functions of the lithium atom dissociative excitation are calculated on the basis of the data obtained

  5. A Systematic Chart Review of Inpatient Population with Childhood Dissociative Disorder

    Science.gov (United States)

    Prabhuswamy, Mukesh; Jairam, Rajeev; Srinath, Shoba; Girimaji, Satish; Seshadri, Shekhar P.

    2006-01-01

    Objective: To study the socio-demographic factors, clinical characteristics, and long-term outcome of dissociative disorders in inpatient children and adolescents. Methods: Chart data of forty-four subjects (8-15 years) with a diagnosis of dissociative disorder admitted to a specialist Child and Adolescent Psychiatry (CAP) unit between September…

  6. A nonaqueous potentiometric titration study of the dissociation of t-butyl methacrylate-methacrylic acid copolymers.

    Science.gov (United States)

    Nakatani, Kiyoharu; Yamashita, Jun; Sekine, Tomomi; Toriumi, Minoru; Itani, Toshiro

    2003-05-01

    The dissociation of t-butyl methacrylate-methacrylic acid copolymers in dimethyl sulfoxide was analyzed by a nonaqueous potentiometric titration technique. The negative logarithm of the dissociation constant of the monomer unit of a methacrylic acid (MAA) monotonously increased with the increasing degree of dissociation corresponding to the titrant/MAA amount ratio, and was highly influenced by the copolymerization ratio. The results are discussed in terms of the suppression of the dissociation of MAA by a neighboring charged methacrylate anion unit.

  7. Structural brain aberrations associated with the dissociative subtype of post-traumatic stress disorder.

    Science.gov (United States)

    Daniels, J K; Frewen, P; Theberge, J; Lanius, R A

    2016-03-01

    One factor potentially contributing to the heterogeneity of previous results on structural grey matter alterations in adult participants suffering from post-traumatic stress disorder (PTSD) is the varying levels of dissociative symptomatology. The aim of this study was therefore to test whether the recently defined dissociative subtype of PTSD characterized by symptoms of depersonalization and derealization is characterized by specific differences in volumetric brain morphology. Whole-brain MRI data were acquired for 59 patients with PTSD. Voxel-based morphometry was carried out to test for group differences between patients classified as belonging (n = 15) vs. not belonging (n = 44) to the dissociative subtype of PTSD. The correlation between dissociation (depersonalization/derealization) severity and grey matter volume was computed. Patients with PTSD classified as belonging to the dissociative subtype exhibited greater grey matter volume in the right precentral and fusiform gyri as well as less volume in the right inferior temporal gyrus. Greater dissociation severity was associated with greater volume in the right middle frontal gyrus. The results of this first whole-brain investigation of specific grey matter volume in dissociative subtype PTSD indentified structural aberrations in regions subserving the processing and regulation of emotional arousal. These might constitute characteristic biomarkers for the dissociative subtype PTSD. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Dissociative subtype of DSM-5 posttraumatic stress disorder in U.S. veterans.

    Science.gov (United States)

    Tsai, Jack; Armour, Cherie; Southwick, Steven M; Pietrzak, Robert H

    2015-01-01

    The Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) formally introduced a dissociative subtype of posttraumatic stress disorder (PTSD). This study examined the proportion of U.S. veterans with DSM-5 PTSD that report dissociative symptoms; and compared veterans with PTSD with and without the dissociative subtype and trauma-exposed controls on sociodemographics, clinical characteristics, and quality of life. Multivariable analyses were conducted on a nationally representative sample of 1484 veterans from the National Health and Resilience in Veterans Study (second baseline survey conducted September-October, 2013). Of the 12.0% and 5.2% of veterans who screened positive for lifetime and past-month DSM-5 PTSD, 19.2% and 16.1% screened positive for the dissociative subtype, respectively. Among veterans with PTSD, those with the dissociative subtype reported more severe PTSD symptoms, comorbid depressive and anxiety symptoms, alcohol use problems, and hostility than those without the dissociative subtype. Adjusting for PTSD symptom severity, those with the dissociative subtype continued to report more depression and alcohol use problems. These results underscore the importance of assessing, monitoring, and treating the considerable proportion of veterans with PTSD and dissociative symptoms. Published by Elsevier Ltd.

  9. The influence of family environment on dissociation in pediatric injury patients.

    Science.gov (United States)

    Nugent, Nicole R; Sledjeski, Eve M; Christopher, Norman C; Delahanty, Douglas L

    2011-10-01

    Emerging support for the roles of both early trauma and family environment in the development of dissociative symptomatology is complicated by the frequent co-occurrence of dysfunctional family environments and childhood maltreatment. The present investigation prospectively examined the influence of family environment on dissociative symptom course in 82 youths (8-18 years) who experienced accidental injury. The primary caretaker reported on six-week family environment (including family cohesion and adaptability) and on youth symptoms of dissociation prior to injury at six weeks and at six months; dissociation prior to injury was assessed via retrospective parent account at the six-week timepoint. Adolescents (aged 11-18) also reported on their own dissociative symptoms at six weeks. Latent growth modeling indicated that youth in more cohesive family environments evidenced decreased symptoms of dissociation at the six-week intercept (z = -2.80). Furthermore, parent income was negatively related to symptoms of dissociation at intercept (z = -1.96) and parent education was associated with a decrease in youth dissociation symptoms over time (z = -2.57). The present findings provide support for the importance of acute family environment in pediatric post-injury adjustment and further highlight the importance of parent resources, including income and education, in post-injury adjustment.

  10. Catch bonding in the forced dissociation of a polymer endpoint

    Science.gov (United States)

    Vrusch, Cyril; Storm, Cornelis

    2018-04-01

    Applying a force to certain supramolecular bonds may initially stabilize them, manifested by a lower dissociation rate. We show that this behavior, known as catch bonding and by now broadly reported in numerous biophysics bonds, is generically expected when either or both the trapping potential and the force applied to the bond possess some degree of nonlinearity. We enumerate possible scenarios and for each identify the possibility and, if applicable, the criterion for catch bonding to occur. The effect is robustly predicted by Kramers theory and Mean First Passage Time theory and confirmed in direct molecular dynamics simulation. Among the catch scenarios, one plays out essentially any time the force on the bond originates in a polymeric object, implying that some degree of catch bond behavior is to be expected in many settings relevant to polymer network mechanics or optical tweezer experiments.

  11. On the determination of double diffraction dissociation cross section at HERA

    International Nuclear Information System (INIS)

    Holtmann, H.; Nikolaev, N.N.; Speth, J.; Zakharov, B.G.

    1996-01-01

    The excitation of the proton into undetected multiparticle states (double diffraction dissociation) is an important background to single diffractive deep-inelastic processes ep→e'p'ρ 0 , e'p'J/Ψ, e'p'X at HERA. We present estimates of the admixture of the double diffraction dissociation events in all diffractive events. We find that in the J/Ψ photoproduction, electroproduction of the ρ 0 at large Q 2 and diffraction dissociation of real and virtual photons into high mass states X the contamination of the double diffraction dissociation can be as large as ∼30%, thus affecting substantially the experimental tests of the pomeron exchange in deep inelastic scattering at HERA. We discuss a possibility of tagging the double diffraction dissociation by neutrons observed in the forward neutron calorimeter. We present evaluations of the spectra of neutrons and efficiency of neutron tagging based on the experimental data for diffractive processes in the proton-proton collisions. (orig.)

  12. Cognitive Abuse within the Incestuous Family as a Factor in the Development of Dissociative Identity Disorder

    Science.gov (United States)

    Reed-Gavish, Maya

    2013-01-01

    The polarized nature of the ongoing controversies surrounding the genesis and validity of dissociative identity disorder pit advocates who see and work with dissociative identity disorder sufferers against skeptics who claim it to be an artificial iatrogenically produced phenomenon. This paper suggests that such a dichotomy is unwarranted and…

  13. Electron Transfer and Collision Induced Dissociation of Non-Derivatized and Derivatized Desmosine and Isodesmosine

    NARCIS (Netherlands)

    Ongay, Sara; Hermans, Jos; Bruins, Andries P.; Nieuwendijk, Adrianus M. C. H.; Overkleeft, Hermen; Bischoff, Rainer

    Electron transfer dissociation (ETD) has attracted increasing interest due to its complementarity to collision-induced dissociation (CID). ETD allows the direct localization of labile post-translational modifications, which is of main interest in proteomics where differences and similarities between

  14. A Genetic Analysis of Individual Differences in Dissociative Behaviors in Childhood and Adolescence

    Science.gov (United States)

    Becker-Blease, Kathryn A.; Deater-Deckard, Kirby; Eley, Thalia; Freyd, Jennifer J.; Stevenson, Jim; Plomin, Robert

    2004-01-01

    Background: Dissociation--a pattern of general disruption in memory and consciousness--has been found to be an important cognitive component of children's and adults' coping with severe trauma. Dissociative experiences include amnesia, identity disturbance, age regression, difficulty with concentration, and trance states. Stable individual…

  15. Effect of oxygen atoms dissociated by non-equilibrium plasma on flame of methane oxygen and argon pre-mixture gas

    Science.gov (United States)

    Akashi, Haruaki; Yoshinaga, Tomokazu; Sasaki, Koichi

    2014-10-01

    For more efficient way of combustion, plasma-assisted combustion has been investigated by many researchers. But it is very difficult to clarify the effect of plasma even on the flame of methane. Because there are many complex chemical reactions in combustion system. Sasaki et al. has reported that the flame length of methane and air premixed burner shortened by irradiating microwave power. They also measured emission from Second Positive Band System of nitrogen during the irradiation. The emission indicates existence of high energy electrons which are accelerated by the microwave. The high energy electrons also dissociate oxygen molecules easily and oxygen atom would have some effects on the flame. But the dissociation ratio of oxygen molecules by the non-equilibrium plasma is significantly low, compared to that in the combustion reaction. To clarify the effect of dissociated oxygen atoms on the flame, dependence of dissociation ratio of oxygen on the flame has been examined using CHEMKIN. It is found that in the case of low dissociation ratio of 10-6, the ignition of the flame becomes slightly earlier. It is also found that in the case of high dissociation ratio of 10-3, the ignition time becomes significantly earlier by almost half. This work was supported by KAKENHI (22340170).

  16. Dissociation of spatial memory systems in Williams syndrome.

    Science.gov (United States)

    Bostelmann, Mathilde; Fragnière, Emilie; Costanzo, Floriana; Di Vara, Silvia; Menghini, Deny; Vicari, Stefano; Lavenex, Pierre; Lavenex, Pamela Banta

    2017-11-01

    Williams syndrome (WS), a genetic deletion syndrome, is characterized by severe visuospatial deficits affecting performance on both tabletop spatial tasks and on tasks which assess orientation and navigation. Nevertheless, previous studies of WS spatial capacities have ignored the fact that two different spatial memory systems are believed to contribute parallel spatial representations supporting navigation. The place learning system depends on the hippocampal formation and creates flexible relational representations of the environment, also known as cognitive maps. The spatial response learning system depends on the striatum and creates fixed stimulus-response representations, also known as habits. Indeed, no study assessing WS spatial competence has used tasks which selectively target these two spatial memory systems. Here, we report that individuals with WS exhibit a dissociation in their spatial abilities subserved by these two memory systems. As compared to typically developing (TD) children in the same mental age range, place learning performance was impaired in individuals with WS. In contrast, their spatial response learning performance was facilitated. Our findings in individuals with WS and TD children suggest that place learning and response learning interact competitively to control the behavioral strategies normally used to support human spatial navigation. Our findings further suggest that the neural pathways supporting place learning may be affected by the genetic deletion that characterizes WS, whereas those supporting response learning may be relatively preserved. The dissociation observed between these two spatial memory systems provides a coherent theoretical framework to characterize the spatial abilities of individuals with WS, and may lead to the development of new learning strategies based on their facilitated response learning abilities. © 2017 Wiley Periodicals, Inc.

  17. First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

    Energy Technology Data Exchange (ETDEWEB)

    Varghese, Jithin J.; Mushrif, Samir H., E-mail: shmushrif@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 (Singapore)

    2015-05-14

    Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu{sub n} where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH{sub 3} and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH{sub x} (x = 1–3) species and recombination of H with CH{sub x} have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters.

  18. First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

    International Nuclear Information System (INIS)

    Varghese, Jithin J.; Mushrif, Samir H.

    2015-01-01

    Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu n where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH 3 and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH x (x = 1–3) species and recombination of H with CH x have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters

  19. Dissociation in small molecules

    International Nuclear Information System (INIS)

    Dehmer, P.M.

    1982-01-01

    The study of molecular dissociation processes is one of the most interesting areas of modern spectroscopy owing to the challenges presented bt even the simplest of diatomic molecules. This paper reviews the commonly used descriptions of molecular dissociation processes for diatomic molecules, the selection rules for predissociation, and a few of the principles to be remembered when one is forced to speculate about dissociation mechanisms in a new molecule. Some of these points will be illustrated by the example of dissociative ionization in O 2

  20. Dissociative experiences and quality of life in patients with non-epileptic attack disorder.

    Science.gov (United States)

    Mitchell, James W; Ali, Fizzah; Cavanna, Andrea E

    2012-11-01

    Dissociative experiences are commonly reported by patients with non-epileptic attack disorder (NEAD). This cross-sectional study examined the prevalence and characteristics of dissociative experiences in patients with NEAD and assessed their association with health-related quality of life (HRQoL). Fifty-three patients diagnosed with NEAD were consecutively recruited (70.0% female, mean age=42 years, 22.0% with comorbid epilepsy) from a specialist neuropsychiatric clinic. Our sample reported high levels of dissociative experiences, with 36.7% of patients scoring ≥30 on the Dissociative Experiences Scale (DES). Significant negative correlations were found between total DES scores and HRQoL, as measured by the QOLIE-31 questionnaire (r=-0.64, pdissociative experiences in this patient population, highlighting the importance of routinely screening patients for dissociative symptoms and their impact on patients' lives. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. On the absolute photoionization cross section and dissociative photoionization of cyclopropenylidene.

    Science.gov (United States)

    Holzmeier, Fabian; Fischer, Ingo; Kiendl, Benjamin; Krueger, Anke; Bodi, Andras; Hemberger, Patrick

    2016-04-07

    We report the determination of the absolute photoionization cross section of cyclopropenylidene, c-C3H2, and the heat of formation of the C3H radical and ion derived by the dissociative ionization of the carbene. Vacuum ultraviolet (VUV) synchrotron radiation as provided by the Swiss Light Source and imaging photoelectron photoion coincidence (iPEPICO) were employed. Cyclopropenylidene was generated by pyrolysis of a quadricyclane precursor in a 1 : 1 ratio with benzene, which enabled us to derive the carbene's near threshold absolute photoionization cross section from the photoionization yield of the two pyrolysis products and the known cross section of benzene. The cross section at 9.5 eV, for example, was determined to be 4.5 ± 1.4 Mb. Upon dissociative ionization the carbene decomposes by hydrogen atom loss to the linear isomer of C3H(+). The appearance energy for this process was determined to be AE(0K)(c-C3H2; l-C3H(+)) = 13.67 ± 0.10 eV. The heat of formation of neutral and cationic C3H was derived from this value via a thermochemical cycle as Δ(f)H(0K)(C3H) = 725 ± 25 kJ mol(-1) and Δ(f)H(0K)(C3H(+)) = 1604 ± 19 kJ mol(-1), using a previously reported ionization energy of C3H.

  2. Threshold collision-induced dissociation of diatomic molecules: a case study of the energetics and dynamics of O2- collisions with Ar and Xe.

    Science.gov (United States)

    Ahu Akin, F; Ree, Jongbaik; Ervin, Kent M; Kyu Shin, Hyung

    2005-08-08

    The energetics and dynamics of collision-induced dissociation of O2- with Ar and Xe targets are studied experimentally using guided ion-beam tandem mass spectrometry. The cross sections and the collision dynamics are modeled theoretically by classical trajectory calculations. Experimental apparent threshold energies are 2.1 and 1.1 eV in excess of the thermochemical O2- bond dissociation energy for argon and xenon, respectively. Classical trajectory calculations confirm the observed threshold behavior and the dependence of cross sections on the relative kinetic energy. Representative trajectories reveal that the bond dissociation takes place on a short time scale of about 50 fs in strong direct collisions. Collision-induced dissociation is found to be remarkably restricted to the perpendicular approach of ArXe to the molecular axis of O2-, while collinear collisions do not result in dissociation. The higher collisional energy-transfer efficiency of xenon compared with argon is attributed to both mass and polarizability effects.

  3. Threshold collision-induced dissociation of diatomic molecules: A case study of the energetics and dynamics of O2- collisions with Ar and Xe

    International Nuclear Information System (INIS)

    Ahu Akin, F.; Ree, Jongbaik; Ervin, Kent M.; Hyung, Kyu Shin

    2005-01-01

    The energetics and dynamics of collision-induced dissociation of O 2 - with Ar and Xe targets are studied experimentally using guided ion-beam tandem mass spectrometry. The cross sections and the collision dynamics are modeled theoretically by classical trajectory calculations. Experimental apparent threshold energies are 2.1 and 1.1 eV in excess of the thermochemical O 2 - bond dissociation energy for argon and xenon, respectively. Classical trajectory calculations confirm the observed threshold behavior and the dependence of cross sections on the relative kinetic energy. Representative trajectories reveal that the bond dissociation takes place on a short time scale of about 50 fs in strong direct collisions. Collision-induced dissociation is found to be remarkably restricted to the perpendicular approach of Ar/Xe to the molecular axis of O 2 - , while collinear collisions do not result in dissociation. The higher collisional energy-transfer efficiency of xenon compared with argon is attributed to both mass and polarizability effects

  4. Theoretical Investigation of Hydrogen Adsorption and Dissociation on Iron and Iron Carbide Surfaces Using the ReaxFF Reactive Force Field Method

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Chenyu; van Duin, Adri C.T.; Sorescu, Dan C.

    2012-06-01

    We have developed a ReaxFF reactive force field to describe hydrogen adsorption and dissociation on iron and iron carbide surfaces relevant for simulation of Fischer–Tropsch (FT) synthesis on iron catalysts. This force field enables large system (>>1000 atoms) simulations of hydrogen related reactions with iron. The ReaxFF force field parameters are trained against a substantial amount of structural and energetic data including the equations of state and heats of formation of iron and iron carbide related materials, as well as hydrogen interaction with iron surfaces and different phases of bulk iron. We have validated the accuracy and applicability of ReaxFF force field by carrying out molecular dynamics simulations of hydrogen adsorption, dissociation and recombination on iron and iron carbide surfaces. The barriers and reaction energies for molecular dissociation on these two types of surfaces have been compared and the effect of subsurface carbon on hydrogen interaction with iron surface is evaluated. We found that existence of carbon atoms at subsurface iron sites tends to increase the hydrogen dissociation energy barrier on the surface, and also makes the corresponding hydrogen dissociative state relatively more stable compared to that on bare iron. These properties of iron carbide will affect the dissociation rate of H{sub 2} and will retain more surface hydride species, thus influencing the dynamics of the FT synthesis process.

  5. Elastic and proton-dissociative photoproduction of J/{psi} mesons at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A. [Yerevan Physics Institute (Armenia)] [and others; Collaboration: H1 Collaboration

    2013-04-15

    Cross sections for elastic and proton-dissociative photoproduction of J/{psi} mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies {radical}(s){approx}318 GeV and {radical}(s){approx}225 GeV, corresponding to integrated luminosities of L=130 pb{sup -1} and L=10.8 pb{sup -1}, respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25dissociation. The results are compared to other measurements. The W{sub {gamma}p} and t-dependences are parametrised using phenomenological fits.

  6. Elastic and proton-dissociative photoproduction of J/{psi} mesons at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Alexa, C.; Dobre, M.; Rotaru, M.; Stoicea, G. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V.; Belousov, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Vazdik, Y. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A.; Baghdasaryan, S.; Zohrabyan, H. [Yerevan Physics Institute, Yerevan (Armenia); Bartel, W.; Belov, P.; Brinkmann, M.; Britzger, D.; Campbell, A.J.; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Gouzevitch, M.; Grebenyuk, A.; Habib, S.; Haidt, D.; Kleinwort, C.; Kraemer, M.; Krueger, K.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Olsson, J.E.; Ozerov, D.; Pahl, P.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Radescu, V.; Schmitt, S.; Sefkow, F.; Shushkevich, S.; South, D.; Steder, M.; Wuensch, E. [DESY, Hamburg (Germany); Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Boudry, V.; Specka, A. [Ecole Polytechnique, CNRS/IN2P3, LLR, Palaiseau (France); Bozovic-Jelisavcic, I.; Pandurovic, M. [University of Belgrade, Vinca Institute of Nuclear Sciences, Belgrade (Serbia); Brandt, G. [Oxford University, Department of Physics, Oxford (United Kingdom); Brisson, V.; Jacquet, M.; Pascaud, C.; Zhang, Z.; Zomer, F. [Universite Paris-Sud, CNRS/IN2P3, LAL, Orsay (France); Buniatyan, A.; Huber, F.; Pirumov, H.; Sauter, M.; Schoening, A. [Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Bylinkin, A.; Bystritskaya, L.; Fedotov, A.; Lubimov, V.; Rostovtsev, A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Cantun Avila, K.B.; Contreras, J.G.; Ruiz Tabasco, J.E. [CINVESTAV, Departamento de Fisica Aplicada, Merida, Yucatan (Mexico); Ceccopieri, F.; Wolf, E.A. de; Favart, L.; Hreus, T.; Janssen, X.; Roosen, R.; Staykova, Z.; Mechelen, P. van [Inter-University Institute for High Energies ULB-VUB, Brussels (Belgium); Universiteit Antwerpen, Antwerpen (Belgium); Cerny, K.; Pokorny, B.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Zlebcik, R. [Charles University, Faculty of Mathematics and Physics, Praha (Czech Republic); Chekelian, V.; Grindhammer, G.; Kiesling, C. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Cvach, J.; Hladky, J.; Reimer, P.; Zalesak, J. [Academy of Sciences of the Czech Republic, Institute of Physics, Praha (Czech Republic); Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D. [University of Liverpool, Department of Physics, Liverpool (United Kingdom); Daum, K.; Meyer, H. [Universitaet Wuppertal, Fachbereich C, Wuppertal (Germany); Diaconu, C.; Hoffmann, D.; Sauvan, E.; Vallee, C. [Aix-Marseille Univ, CNRS/IN2P3, CPPM, Marseille (France); Dodonov, V. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Dossanov, A. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Max-Planck-Institut fuer Physik, Muenchen (Germany); Egli, S.; Hildebrandt, M.; Horisberger, R. [Paul Scherrer Institut, Villigen (Switzerland); Feltesse, J.; Perez, E.; Schoeffel, L. [CE-Saclay, CEA, DSM/Irfu, Gif-sur-Yvette (France); Ferencei, J. [Slovak Academy of Sciences, Institute of Experimental Physics, Kosice (Slovakia); Goerlich, L.; Mikocki, S.; Milcewicz-Mika, I.; Nowak, G.; Sopicki, P.; Turnau, J. [Institute for Nuclear Physics, Cracow (Poland); Grab, C. [ETH, Institut fuer Teilchenphysik, Zuerich (Switzerland); Henderson, R.C.W. [University of Lancaster, Department of Physics, Lancaster (United Kingdom); Hennekemper, E.; Herbst, M.; Schultz-Coulon, H.C. [Universitaet Heidelberg, Kirchhoff-Institut fuer Physik, Heidelberg (Germany); Herrera, G.; Lopez-Fernandez, R. [CINVESTAV IPN, Departamento de Fisica, Mexico City (Mexico); Hiller, K.H.; Kostka, P.; Lange, W.; Naumann, T. [DESY, Zeuthen (Germany); Joensson, L. [University of Lund, Physics Department, Lund (Sweden); Jung, H. [Inter-University Institute for High Energies ULB-VUB, Brussels (Belgium); Universiteit Antwerpen, Antwerpen (Belgium); DESY, Hamburg (Germany); Kapichine, M.; Morozov, A.; Nikitin, D.; Palichik, V.; Spaskov, V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kogler, R.; Nowak, K. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (Germany); Landon, M.P.J.; Rizvi, E.; Traynor, D. [Queen Mary, University of London, School of Physics and Astronomy, London (United Kingdom); Martyn, H.U. [I. Physikalisches Institut der RWTH, Aachen (Germany); Morris, J.V.; Sankey, D.P.C. [STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire (United Kingdom); Mueller, K.; Robmann, P.; Straumann, U.; Truoel, P. [Physik-Institut der Universitaet Zuerich, Zuerich (Switzerland); Newman, P.R.; Thompson, P.D. [University of Birmingham, School of Physics and Astronomy, Birmingham (United Kingdom); Picuric, I.; Raicevic, N. [University of Montenegro, Faculty of Science, Podgorica (Montenegro); Soloviev, Y. [DESY, Hamburg (Germany); Lebedev Physical Institute, Moscow (Russian Federation); Stella, B. [Universita di Roma Tre (Italy); INFN Roma 3, Dipartimento di Fisica, Roma (Italy); Sykora, T. [Inter-University Institute for High Energies ULB-VUB, Brussels (Belgium); Universiteit Antwerpen, Antwerpen (Belgium); Charles University, Faculty of Mathematics and Physics, Praha (Czech Republic); Tsakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Wegener, D. [TU Dortmund, Institut fuer Physik, Dortmund (Germany); Collaboration: The H1 Collaboration

    2013-06-15

    Cross sections for elastic and proton-dissociative photoproduction of J/{psi} mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies {radical}(s) {approx} 318 GeV and {radical}(s) {approx} 225 GeV, corresponding to integrated luminosities of L = 130 pb{sup -1} and L = 10.8 pb{sup -1}, respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25 < W{sub {gamma}p} < 110 GeV. Differential cross sections d {sigma}/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range vertical stroke t vertical stroke < 1.2 GeV{sup 2} for the elastic process and vertical stroke t vertical stroke <8 GeV{sup 2} for proton dissociation. The results are compared to other measurements. The W{sub {gamma}p} and t-dependences are parametrised using phenomenological fits. (orig.)

  7. A DFT Study of R-X Bond Dissociation Enthalpies of Relevance to the Initiation Process of Atom Transfer Radical Polymerization

    DEFF Research Database (Denmark)

    Gillies, Malcolm Bjørn; Matyjaszewski, Krzysztof; Norrby, Per-Ola

    2003-01-01

    DFT calculations at the B3P86/6-31G** level have been carried out to derive the bond dissociation energies (BDE) and free energies for a number of R-X systems (X ) Cl, Br, I, N3, and S2-CNMe2) that have been or can potentially be used as initiators for atom transfer radical polymerization (ATRP...

  8. Dissociable spatial and temporal effects of inhibition of return.

    Directory of Open Access Journals (Sweden)

    Zhiguo Wang

    Full Text Available Inhibition of return (IOR refers to the relative suppression of processing at locations that have recently been attended. It is frequently explored using a spatial cueing paradigm and is characterized by slower responses to cued than to uncued locations. The current study investigates the impact of IOR on overt visual orienting involving saccadic eye movements. Using a spatial cueing paradigm, our experiments have demonstrated that at a cue-target onset asynchrony (CTOA of 400 ms saccades to the vicinity of cued locations are not only delayed (temporal cost but also biased away (spatial effect. Both of these effects are basically no longer present at a CTOA of 1200 ms. At a shorter 200 ms CTOA, the spatial effect becomes stronger while the temporal cost is replaced by a temporal benefit. These findings suggest that IOR has a spatial effect that is dissociable from its temporal effect. Simulations using a neural field model of the superior colliculus (SC revealed that a theory relying on short-term depression (STD of the input pathway can explain most, but not all, temporal and spatial effects of IOR.

  9. High-Pressure-Driven Reversible Dissociation of α-Synuclein Fibrils Reveals Structural Hierarchy.

    Science.gov (United States)

    Piccirilli, Federica; Plotegher, Nicoletta; Ortore, Maria Grazia; Tessari, Isabella; Brucale, Marco; Spinozzi, Francesco; Beltramini, Mariano; Mariani, Paolo; Militello, Valeria; Lupi, Stefano; Perucchi, Andrea; Bubacco, Luigi

    2017-10-17

    The analysis of the α-synuclein (aS) aggregation process, which is involved in Parkinson's disease etiopathogenesis, and of the structural feature of the resulting amyloid fibrils may shed light on the relationship between the structure of aS aggregates and their toxicity. This may be considered a paradigm of the ground work needed to tackle the molecular basis of all the protein-aggregation-related diseases. With this aim, we used chemical and physical dissociation methods to explore the structural organization of wild-type aS fibrils. High pressure (in the kbar range) and alkaline pH were used to disassemble fibrils to collect information on the hierarchic pathway by which distinct β-sheets sequentially unfold using the unique possibility offered by high-pressure Fourier transform infrared spectroscopy. The results point toward the formation of kinetic traps in the energy landscape of aS fibril disassembly and the presence of transient partially folded species during the process. Since we found that the dissociation of wild-type aS fibrils by high pressure is reversible upon pressure release, the disassembled molecules likely retain structural information that favors fibril reformation. To deconstruct the role of the different regions of aS sequence in this process, we measured the high-pressure dissociation of amyloids formed by covalent chimeric dimers of aS (syn-syn) and by the aS deletion mutant that lacks the C-terminus, i.e., aS (1-99). The results allowed us to single out the role of dimerization and that of the C-terminus in the complete maturation of fibrillar aS. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Adsorption and dissociation of H2S on Mo(1 0 0) surface by first-principles study

    International Nuclear Information System (INIS)

    Luo, Haijun; Cai, Jianqiu; Tao, Xiangming; Tan, Mingqiu

    2014-01-01

    Density-functional theory calculations had been used to investigate the adsorption and dissociation of H 2 S on Mo(1 0 0) surface. Adsorption mechanisms of H 2 S, HS, S and H on the Mo(1 0 0) surface were analyzed. H 2 S was found to be adsorbed at bridge, hollow and top sites with adsorption energies of −1.25, −1.03 and −0.92 eV, respectively. HS was strongly chemically absorbed at hollow, bridge and top sites with adsorption energies of −4.51, −4.08 and −3.45 eV, respectively, and sulfur and hydrogen preferred to be absorbed at hollow and bridge sites, respectively. In addition, potential energy profiles of H 2 S dissociation on Mo(1 0 0) had been constructed by a climbing image nudged elastic band method. Four possible dissociation pathways of the first H 2 S dehydrogenation were examined with reaction barriers of 0.28, 0.37, 0.075, and 0.21 eV, respectively, while the energy barrier to break the S-H bond of HS with or without hydrogen co-adsorption was almost the same low. This work showed that the decomposition of H 2 S on the molybdenum surface was kinetically and thermodynamically facile. Local densities of electronic states were further used to characterize the interaction between H 2 S and substrate.

  11. Dissociative symptoms and dissociative disorders comorbidity in obsessive compulsive disorder: Symptom screening, diagnostic tools and reflections on treatment

    OpenAIRE

    Belli, Hasan

    2014-01-01

    Borderline personality disorder, conversion disorder and obsessive compulsive disorder frequently have dissociative symptoms. The literature has demonstrated that the level of dissociation might be correlated with the severity of obsessive compulsive disorder (OCD) and that those not responding to treatment had high dissociative symptoms. The structured clinical interview for DSM-IV dissociative disorders, dissociation questionnaire, somatoform dissociation questionnaire and dissociative expe...

  12. Electromagnetic dissociation of relativistic 28Si by nucleon emission

    Energy Technology Data Exchange (ETDEWEB)

    Sonnadara, Upal Jayasiri [Univ. of Pittsburgh, PA (United States)

    1992-12-01

    A detailed study of the electromagnetic dissociation of 28Si by nucleon emission at Elab/A = 14.6 (GeV/nucleon was carried out with 28Si beams interacting on 208Pb). 120Sn. 64C targets. The measurements apparatus consists of detectors in the target area which measure the energy and charged multiplicity, and a forward spectrometer which measures the position, momentum and energy of the reaction fragments. The exclusive electromagnetic dissociation cross sections for decay channels having multiple nucleons in the final state have been measured which enables the selection of events produced in pure electromagnetic interactions. The measured cross sections agree well with previous measurements obtained for the removal of a few nucleons as well as with measurements on total charge removal cross sections from other experiments. The dependence of the integrated cross sections on the target charge ZT and the target mass AT confirms that for higher Z targets the excitation is largely electromagnetic. Direct measurements of the excitation energy for the electromagnetic dissociation of 28Si → p+27Al and 28Si → n+27Si have been obtained through a calculation of the invariant mass in kinematically, reconstructed events. The excitation energy spectrum for all targets peak near the isovector giant dipole resonance in 28Si. These distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear 28Si(γ,p)27Al and 28Si(γ,n)27Si. The possibilities of observing double giant dipole resonance excitations in 28Si have been investigated with cross section measurements as well as with excitation energy reconstruction.

  13. A first principle study for the adsorption and absorption of carbon atom and the CO dissociation on Ir(100) surface

    Energy Technology Data Exchange (ETDEWEB)

    Erikat, I. A., E-mail: ihsanas@yahoo.com [Department of Physics, Jerash University, Jerash-26150 (Jordan); Hamad, B. A. [Department of Physics, The University of Jordan, Amman-11942 (Jordan)

    2013-11-07

    We employ density functional theory to examine the adsorption and absorption of carbon atom as well as the dissociation of carbon monoxide on Ir(100) surface. We find that carbon atoms bind strongly with Ir(100) surface and prefer the high coordination hollow site for all coverages. In the case of 0.75 ML coverage of carbon, we obtain a bridging metal structure due to the balance between Ir–C and Ir–Ir interactions. In the subsurface region, the carbon atom prefers the octahedral site of Ir(100) surface. We find large diffusion barrier for carbon atom into Ir(100) surface (2.70 eV) due to the strong bonding between carbon atom and Ir(100) surface, whereas we find a very small segregation barrier (0.22 eV) from subsurface to the surface. The minimum energy path and energy barrier for the dissociation of CO on Ir(100) surface are obtained by using climbing image nudge elastic band. The energy barrier of CO dissociation on Ir(100) surface is found to be 3.01 eV, which is appreciably larger than the association energy (1.61 eV) of this molecule.

  14. A first principle study for the adsorption and absorption of carbon atom and the CO dissociation on Ir(100) surface

    Science.gov (United States)

    Erikat, I. A.; Hamad, B. A.

    2013-11-01

    We employ density functional theory to examine the adsorption and absorption of carbon atom as well as the dissociation of carbon monoxide on Ir(100) surface. We find that carbon atoms bind strongly with Ir(100) surface and prefer the high coordination hollow site for all coverages. In the case of 0.75 ML coverage of carbon, we obtain a bridging metal structure due to the balance between Ir-C and Ir-Ir interactions. In the subsurface region, the carbon atom prefers the octahedral site of Ir(100) surface. We find large diffusion barrier for carbon atom into Ir(100) surface (2.70 eV) due to the strong bonding between carbon atom and Ir(100) surface, whereas we find a very small segregation barrier (0.22 eV) from subsurface to the surface. The minimum energy path and energy barrier for the dissociation of CO on Ir(100) surface are obtained by using climbing image nudge elastic band. The energy barrier of CO dissociation on Ir(100) surface is found to be 3.01 eV, which is appreciably larger than the association energy (1.61 eV) of this molecule.

  15. A first principle study for the adsorption and absorption of carbon atom and the CO dissociation on Ir(100) surface

    International Nuclear Information System (INIS)

    Erikat, I. A.; Hamad, B. A.

    2013-01-01

    We employ density functional theory to examine the adsorption and absorption of carbon atom as well as the dissociation of carbon monoxide on Ir(100) surface. We find that carbon atoms bind strongly with Ir(100) surface and prefer the high coordination hollow site for all coverages. In the case of 0.75 ML coverage of carbon, we obtain a bridging metal structure due to the balance between Ir–C and Ir–Ir interactions. In the subsurface region, the carbon atom prefers the octahedral site of Ir(100) surface. We find large diffusion barrier for carbon atom into Ir(100) surface (2.70 eV) due to the strong bonding between carbon atom and Ir(100) surface, whereas we find a very small segregation barrier (0.22 eV) from subsurface to the surface. The minimum energy path and energy barrier for the dissociation of CO on Ir(100) surface are obtained by using climbing image nudge elastic band. The energy barrier of CO dissociation on Ir(100) surface is found to be 3.01 eV, which is appreciably larger than the association energy (1.61 eV) of this molecule

  16. Spectroscopic probes of vibrationally excited molecules at chemically significant energies

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, T.R. [Univ. of Rochester, NY (United States)

    1993-12-01

    This project involves the application of multiple-resonance spectroscopic techniques for investigating energy transfer and dissociation dynamics of highly vibrationally excited molecules. Two major goals of this work are: (1) to provide information on potential energy surfaces of combustion related molecules at chemically significant energies, and (2) to test theoretical modes of unimolecular dissociation rates critically via quantum-state resolved measurements.

  17. Quantum dynamics of water dissociative chemisorption on rigid Ni(111): An approximate nine-dimensional treatment

    International Nuclear Information System (INIS)

    Jiang, Bin; Song, Hongwei; Yang, Minghui; Guo, Hua

    2016-01-01

    The quantum dynamics of water dissociative chemisorption on the rigid Ni(111) surface is investigated using a recently developed nine-dimensional potential energy surface. The quantum dynamical model includes explicitly seven degrees of freedom of D 2 O at fixed surface sites, and the final results were obtained with a site-averaging model. The mode specificity in the site-specific results is reported and analyzed. Finally, the approximate sticking probabilities for various vibrationally excited states of D 2 O are obtained considering surface lattice effects and formally all nine degrees of freedom. The comparison with experiment reveals the inaccuracy of the density functional theory and suggests the need to improve the potential energy surface.

  18. Zero photon dissociation of CS2+ in intense ultrashort laser pulses

    Science.gov (United States)

    Severt, Travis; Betsch, K. J.; Zohrabi, M.; Ablikim, U.; Jochim, Bethany; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.

    2013-05-01

    We measured the dissociation of a CS2+ molecular ion beam in intense laser pulses ( C+ + S+. We speculate that a pump-dump process occurs whereby the vibrational wavepacket in the electronic ground state of CS2+ is pumped into the electronic first excited state's continuum by a single photon during the laser pulse. Once this continuum vibrational wavepacket passes the potential barrier in the ground electronic potential, the emission of a second photon is stimulated by the same laser pulse, most likely when the wavepacket moves through the internuclear distance where the two electronic states are in resonance with the driving field. A comparison is made to ZPD and ATD in the isovalent CO2+ species. Curiously, ATD is the favored mechanism in CO2+. The underlying molecular structure and dynamics determining this preference will be discussed. Supported by Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  19. Universal imaging: Dissociative ionization of polyatomic molecules, chemical dynamics beamline 9.0.2

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.; Chen, D.; Suits, A.G. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    A third endstation was recently added to the Chemical Dynamics beamline, designed to exploit the high flux broadband undulator light for a range of studies of reactive scattering, photochemistry and photoionization processes using time-of-flight mass spectroscopy coupled with position-sensitive detection. Two molecular beam sources are fixed at right angles, with the undulator light, or laser beams, intersecting the molecular beams at 45{degrees}. To date, beamline experiments have included a study of dissociative photoionization of a variety of molecules including N{sub 2}O and SF{sub 6}. In this mode, a single molecular beam source is used, with the tunable undulator light inducing, in SF{sub 6} for example, the process SF{sub 6} {r_arrow} SF{sub 6}{sup +} + e{sup {minus}} {r_arrow} SF{sub 5}{sup +} + F + e{sup {minus}}. The SF{sub 5}{sup +} ions are accelerated up the flight tube, mass selected and detected as a function of position on a phosphor screen viewed by a CCD camera. The position directly reveals the recoil speed (or translational energy release) and angular distribution for the dissociative ionization process. Furthermore, this measurement is obtained for all recoil speeds and angles simultaneously. Such detailed angular information has not previously been obtained for dissociative ionization processes; typically ion time-of-flight profiles are deconvoluted to yield rough insight into the angular distributions. The recorded image is actually a 2-dimensional projection of the nascent 3-dimensional velocity distribution, but established tomographic techniques enable the authors to reconstruct the 3-D distribution.

  20. Numerical simulation of the electrodeionization (EDI) process accounting for water dissociation

    International Nuclear Information System (INIS)

    Lu Jun; Wang Yuxin; Zhu Jia

    2010-01-01

    The electrodeionization process (EDI) is usually operated at overlimiting current density, and is thus characterized by water dissociation and concentration polarization. We attempt to study the useful and harmful effects of water dissociation on the EDI process. A numerical steady state model was established to simulate the process of EDI, accounting for the effects of water dissociation. The differences in concentration polarization of membranes were investigated to study the effects of water dissociation on cation and anion membranes. Protons produced by water dissociation caused the resin to transform into the H-form. The H-form resin, which has high conductivity and high transport number, depletes protons in the interstitial solution. This explains the experimentally detected phenomenon that at high current densities, the pH value of the effluency of the dilute compartment (DC) stops decreasing when current increases. We suggest that the useful role of water dissociation in EDI is due to the H-form resin bringing more salt cations of the interstitial solution into the resin phase, thus producing a high conductivity channel for the electro-migration of the salt cations. This mechanism avoids the decrease in salt ion conductivity brought about by concentration polarization. The disadvantageous effect of concentration polarization on the transportation of salt ions in interstitial solution is thus lessened. An intermediate point between the useful and harmful effects of water dissociation was determined by the dependence of current efficiency and removal rate for both cations and anions as a function of current density.

  1. The assignment of dissociative electron attachment bands in compounds containing hydroxyl and amino groups

    International Nuclear Information System (INIS)

    Skalicky, Tomas; Allan, Michael

    2004-01-01

    Dissociative electron attachment (DEA) spectra were recorded for methanol, phenol, diethylamine, tetramethylhydrazine, piperazine, pyrrole and N,N-dimethylaniline. Comparison with He I photoelectron spectra permitted the assignment of virtually all DEA bands in the saturated compounds to core excited Feshbach resonances with double occupation of Rydberg-like orbitals and various Koopmans' states of the positive ion as a core. These resonances shift to lower energies with alkyl substitution, in contrast to the shape resonances, and are found at surprisingly low energies in the amines. The DEA spectra in the unsaturated compounds show no or only weak evidence for the Rydberg-type Feshbach resonances. It is proposed that DEA in saturated polyatomic molecules containing hydroxyl and amino groups is in general dominated by this type of resonance

  2. Experimental investigation of methane release from hydrate formation in sandstone through both hydrate dissociation and CO{sub 2} sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Husebo, J.; Graue, A.; Kvamme, B. [Bergen Univ., Bergen (Norway). Dept. of Physics and Technology; Stevens, J.; Howard, J.J. [ConocoPhillips, Ponca City, OK (United States); Baldwin, B.A. [Green Country Petrophysics LLC, Dewey, OK (United States)

    2008-07-01

    Large amounts of natural gas trapped in hydrate reservoirs are found in Arctic regions and in deep offshore locations around the world. Natural gas production from hydrate deposits offer significant potential for future energy needs. However, research is needed in order to propose potential production schemes for natural gas hydrates. Natural gas molecules can be freed from hydrate structured cages by depressurization, by heating and by exposing the hydrate to a substance that will form a thermodynamically more stable hydrate structure. This paper provided a comparison of two approaches for releasing methane from methane hydrate in porous sandstone. The study scope covered the dissociation rate of methane hydrate in porous media through depressurization, and also referred to previous work done on producing methane from hydrates in sandstone while sequestering carbon dioxide (CO{sub 2}). The study was conducted in a laboratory setting. The paper discussed the experimental design which included the placing of a pressure- and temperature-controlled sample holder inside the bore of a magnetic resonance imager. The experimental procedures were then outlined, with reference to hydrate formation; carbon dioxide sequestration; hydrate dissociation experiments with constant volume; and hydrate dissociation experiments at constant pressure. The constant volume experiments demonstrated that in order to dissociate a large amount of hydrate, the initial depressurization had to be significantly lower than the hydrate stability pressure. 9 refs., 9 figs.

  3. Dissociated language functions: a matter of atypical language lateralization or cerebral plasticity?

    Science.gov (United States)

    Acioly, Marcus Andre; Gharabaghi, Alireza; Zimmermann, Christoph; Erb, Michael; Heckl, Stefan; Tatagiba, Marcos

    2014-01-01

    The left hemisphere is generally considered to harbor language functions. Atypical cortical language lateralization is mainly demonstrated in left-handed and ambidextrous individuals, whereas dissociated language functions have been reported in association with brain injuries as a part of the reorganization process. We present a thoughtful discussion on the underlying mechanisms of dissociated language functions through an illustrative case of dissociated expressive language. A 31-year-old left-handed woman presented with a recurrent left frontal glioma. Preoperative language functional magnetic resonance imaging (fMRI) panel revealed right-sided dominance for two different language tasks (verbal fluency and visual naming), and the word chain task demonstrated maximal activation in the left hemisphere at the posterior margin of the tumor. The patient was operated on awake to assess language functions intraoperatively. Preoperative fMRI findings were confirmed revealing a task-specific dissociation of expressive language functions. Surgical resection was taken to the functional boundaries. Postoperatively, no language dysfunction occurred. Dissociated language functions are prone to occur in long-standing lesions. Different patterns of dissociation may be encountered due to interindividual particularities and cerebral plasticity. The presented patient is unique by demonstrating new insight into expressive language dissociation, emphasizing the role of a preoperative language fMRI panel and the capability of intraoperative language mapping for identifying special language networks. Georg Thieme Verlag KG Stuttgart · New York.

  4. Depression and Dissociation as Predictors of Physical Health Symptoms Among Female Rape Survivors with PTSD

    Science.gov (United States)

    Scioli-Salter, Erica R.; Johnides, Benjamin D.; Mitchell, Karen S.; Smith, Brian N.; Resick, Patricia A.; Rasmusson, Ann M.

    2016-01-01

    Objective To investigate the relative contributions of depression and dissociation, as well as PTSD, to physical health symptoms and to examine the relationships among somatic symptoms, PTSD, depression, and dissociation in relation to childhood and adult trauma exposure. Method Cross-sectional data are from 132 female rape survivors with PTSD assessed prior to engaging in a study of trauma-focused cognitive therapy for PTSD. Measures included the Pennebaker Inventory of Limbic Languidness, Clinician Administered PTSD Scale, Beck Depression Inventory, Trauma Symptom Inventory-Dissociation Subscale, Childhood Sexual Abuse Exposure Questionnaire, and Assessing Environments-III-Physical Punishment Scale. Results Hierarchical regression analyses revealed that only dissociative and depression symptoms contributed significantly to physical health symptoms. Similarly, among the subsample of women with either childhood sexual or physical abuse, depression and dissociation were significant predictors of somatic symptoms. However, among women without childhood abuse, only dissociation significantly predicted somatic symptoms. Conclusion Understanding the psychological and biological mechanisms that link childhood versus adult trauma exposure, PTSD, and comorbid depression or dissociation to physical health symptoms may aid development of individualized treatments for the physical and psychological consequences of trauma. PMID:27149157

  5. Isotope exchange study of the dissociation of metal-humic substance complexes

    International Nuclear Information System (INIS)

    Mizera, J.; Jansova, A.; Hvozdova, I.; Benes, P.; Novak, F.

    2003-01-01

    Isotope exchange was employed to study dissociation of metal cations from their complexes with humic substances (HS). Dissociation of cation from HS controls the rate of isotope exchange between two identical metal-HS solutions (but for the presence of a radiotracer) divided by a dialysis membrane. The rate of isotope exchange of Eu/ 152 Eu and Co/ 60 Co in the systems with various HS was monitored as a function of pH, ionic strength, and the degree of HS loading with metal. The apparent rate of Eu-HS dissociation was found to be enhanced by decreasing pH, increasing ionic strength, and increasing metal loading. Co-HS dissociation was too fast to be followed by the method. For interpretation of the experimental kinetic data, the multiple first order law has been applied. Based on the results, a concept of HS as a mixture of two types of binding sites is discussed. (author)

  6. MRI diagnosis of suspected atlanto-occipital dissociation in childhood

    International Nuclear Information System (INIS)

    Grabb, B.C.; Frye, T.A.; Hedlund, G.L.; Vaid, Y.N.; Royal, S.A.; Grabb, P.A.

    1999-01-01

    Objective. To demonstrate the utility of magnetic resonance (MR) imaging in the diagnosis of complete and partial ligamentous injuries in patients with suspected atlanto-occipital dissociation (AOD). Materials and methods. Five patients with suspected AOD had MR imaging performed within an average of 4 days after injury. MR scans were reviewed with specific analysis of craniocervical ligamentous structures. Charts were reviewed to obtain clinical information regarding presentation, treatment, hospital course, and outcome. Results. Two patients demonstrated MR evidence of complete AOD. One had disruption of all visualized major ligamentous structures at the craniocervical junction with anterolisthesis and evidence of cord damage. The second had injuries to the tectorial membrane, superior band of the cruciform ligament, apical ligament, and interspinous ligament at C 1-2. The re