WorldWideScience

Sample records for quasi-free reactions

  1. Study of the (p,d/sup 3/He) reaction as a quasi-free reaction process

    Energy Technology Data Exchange (ETDEWEB)

    Cowley, A. A.; Roos, P. G.; Chant, N. S.; Woody, R. III; Holmgren, H. D.; Goldberg, D. A.

    1976-11-01

    The (p,d/sup 3/He) reaction on /sup 6/Li, /sup 7/Li, /sup 9/Be, and /sup 12/C has been investigated in conjunction with studies of the (p,p..cap alpha..) reaction on the same targets. Coincident data for all four targets were obtained at a bombarding energy of 100 MeV for numerous angle pairs in order to test the reaction mechanism. Comparisons of the (p,d/sup 3/He) data to both (p,p..cap alpha..) data and distorted wave impulse approximation calculations (DWIA) indicate a dominance of the direct quasi-free reaction process (p + alpha yields d + /sup 3/He). The absolute alpha-particle spectroscopic factors extracted using DWIA analysis are in agreement with the values obtained in the (p,p..cap alpha..) reaction.

  2. How to determine a dineutron correlation in Borromean nuclei via a quasi-free knockout ($p,pn$) reaction?

    CERN Document Server

    Kikuchi, Yuma; Kubota, Yuki; Sasano, Masaki; Uesaka, Tomohiro

    2016-01-01

    The quasi-free neutron knockout reaction on $^6$He is investigated to discuss the dineutron correlation in the ground state. In the present work, the momentum distributions of the two emitted neutrons are calculated with the $\\alpha$~+~$n$~+~$n$ three-body model and the simple reaction model, and the effects of the knockout process via the $^5$He resonance and the target dependence in the momentum distributions are discussed. From the calculation, it is found that a clear signature of the dineutron correlation can be obtained by choosing the kinematical condition to exclude the process via the $^5$He resonance, while the inclusion of the $^5$He resonance drastically changes the momentum distributions. It is also shown to be important to use the proton target in the quantitative discussion on the dineutron correlation by the knockout reaction. In addition to theoretical arguments, a possible experimental setup to determine the dineutron correlation via the quasi-free knockout reaction is considered.

  3. Exclusive measurements of quasi-free proton scattering reactions in inverse and complete kinematics

    Directory of Open Access Journals (Sweden)

    V. Panin

    2016-02-01

    Full Text Available Quasi-free scattering reactions of the type (p,2p were measured for the first time exclusively in complete and inverse kinematics, using a 12C beam at an energy of ∼400 MeV/u as a benchmark. This new technique has been developed to study the single-particle structure of exotic nuclei in experiments with radioactive-ion beams. The outgoing pair of protons and the fragments were measured simultaneously, enabling an unambiguous identification of the reaction channels and a redundant measurement of the kinematic observables. Both valence and deeply-bound nucleon orbits are probed, including those leading to unbound states of the daughter nucleus. Exclusive (p,2p cross sections of 15.8(18 mb, 1.9(2 mb and 1.5(2 mb to the low-lying 0p-hole states overlapping with the ground state (3/2− and with the bound excited states of 11B at 2.125 MeV (1/2− and 5.02 MeV (3/2−, respectively, were determined via γ-ray spectroscopy. Particle-unstable deep-hole states, corresponding to proton removal from the 0s-orbital, were studied via the invariant-mass technique. Cross sections and momentum distributions were extracted and compared to theoretical calculations employing the eikonal formalism. The obtained results are in a good agreement with this theory and with direct-kinematics experiments. The dependence of the proton–proton scattering kinematics on the internal momentum of the struck proton and on its separation energy was investigated for the first time in inverse kinematics employing a large-acceptance measurement.

  4. Analysis of the exclusive final state npe+e- in the quasi-free np reaction

    Science.gov (United States)

    Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Chlad, L.; Deveaux, C.; Dreyer, J.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Filip, P.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gernhäuser, R.; Golubeva, M.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Kühn, W.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Liu, T.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Morinière, E.; Morozov, S.; Müntz, C.; Münzer, R.; Naumann, L.; Nowakowski, K.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petousis, V.; Petukhov, O.; Pietraszko, J.; Przygoda, W.; Ramos, S.; Ramstein, B.; Reshetin, A.; Rodriguez-Ramos, P.; Rosier, P.; Rost, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Siebenson, J.; Silva, L.; Sobolev, Yu. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tlusty, P.; Traxler, M.; Tsertos, H.; Usenko, E.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Zanevsky, Y.; Zumbruch, P.; Sarantsev, A. V.

    2017-07-01

    We report on the investigation of dielectron production in tagged quasi-free neutron-proton collisions by using a deuteron beam of kinetic energy 1.25GeV/u impinging on a liquid hydrogen target. Our measurements with HADES confirm a significant excess of e+e- pairs above the π0 mass in the exclusive channel dp → npe+e-(p_{spect}) as compared to the exclusive channel ppe+e- measured in proton-proton collisions at the same energy. That excess points to different bremsstrahlung production mechanisms. Two models were evaluated for the role of the charged pion exchange between nucleons and double- Δ excitation combined with intermediate ρ-meson production. Differential cross sections as a function of the e+e- invariant mass and of the angles of the virtual photon, proton and electrons provide valuable constraints and encourage further investigations on both experimental and theoretical sides.

  5. Measurement of spin observables in the quasi-free np-> {pp}_s pi- reaction at 353 MeV

    CERN Document Server

    Dymov, S; Azaryan, T; Barsov, S; Baru, V; Benati, P; Chiladze, D; Dzyuba, A; Engels, R; Gaisser, M; Gebel, R; Grigoryev, K; Goslawski, P; Guidoboni, G; Hartmann, M; Kacharava, A; Kamerdzhiev, V; Khoukaz, A; Komarov, V; Kulessa, P; Kulikov, A; Kurbatov, V; Lehrach, A; Lenisa, P; Lensky, V; Lomidze, N; Lorentz, B; Macharashvili, G; Maier, R; Mchedlishvili, D; Merzliakov, S; Mielke, M; Mikirtychyants, M; Mikirtytchiants, S; Nioradze, M; Oellers, D; Ohm, H; Polyanskiy, A; Papenbrock, M; Prasuhn, D; Rathmann, F; Serdyuk, V; Seyfarth, H; Steffens, E; Stein, H J; Stockhorst, H; Ströher, H; Tabidze, M; Trusov, S; Tsirkov, D; Uzikov, Yu; Valdau, Yu; Weidemann, Ch; Wilkin, C; Wüstner, P; Ye, Q J; Zhabitsky, M

    2013-01-01

    The transverse spin correlations A_{x,x} and A_{y,y} have been measured in the pol{d} pol{p} -> p_spec {pp}_s pi- reaction at COSY-ANKE at 353 MeV per nucleon. Here {pp}_s denotes a proton-proton pair with low excitation energy, which is dominantly in the 1S0 state. By measuring three protons in the final state it was possible to extract events where there was a spectator proton p_spec so that the reaction could be interpreted in terms of quasi-free pol{n} pol{p} -> {pp}_s pi-. The proton analyzing power in this reaction was also deduced from this data set by averaging over the polarization of the deuteron beam. The values of A_y^p were shown to be consistent with a refined analysis of our earlier results obtained with a polarized proton incident on a deuterium target. Taking these data in combination with our earlier measurements of the differential cross sections and analyzing powers in the pol{p} p -> {pp}_s pi^0 reaction, a more robust partial wave decomposition was achieved. Three different acceptable so...

  6. Study of the quasi-free np→npπ+π− reaction with a deuterium beam at 1.25 GeV/nucleon

    Directory of Open Access Journals (Sweden)

    G. Agakishiev

    2015-11-01

    Full Text Available The tagged quasi-free np→npπ+π− reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon (s∼2.42 GeV/c for the quasi-free collision. For the first time, differential distributions of solid statistics for π+π− production in np collisions have been collected in the region corresponding to the large transverse momenta of the secondary particles. The invariant mass and angular distributions for the np→npπ+π− reaction are compared with different models. This comparison confirms the dominance of the t-channel with ΔΔ contribution. It also validates the changes previously introduced in the Valencia model to describe two-pion production data in other isospin channels, although some deviations are observed, especially for the π+π− invariant mass spectrum. The extracted total cross section is also in much better agreement with this model. Our new measurement puts useful constraints for the existence of the conjectured dibaryon resonance at mass M∼2.38 GeV and with width Γ∼70 MeV.

  7. Study of the quasi-free $np \\to np \\pi^+\\pi^-$ reaction with a deuterium beam at 1.25 GeV/nucleon

    CERN Document Server

    Agakishiev, G; Belver, D; Belyaev, A V; Blanco, A; Böhmer, M; Boyard, J L; Braun-Munzinger, P; Cabanelas, P; Castro, E; Chernenko, S; Christ, T; Destefanis, M; Díaz, J; Dohrmann, F; Dybczak, A; Fabbietti, L; Fateev, O V; Finocchiaro, P; Fonte, P; Friese, J; Fröhlich, I; Galatyuk, T; Garzón, J A; Gernhäuser, R; Gil, A; Gilardi, C; Göbel, K; Golubeva, M; González-Díaz, D; Guber, F; Gumberidze, M; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kämpfer, B; Karavicheva, T; Kirschner, D; Koenig, I; Koenig, W; Kolb, B W; Kotte, R; Krizek, F; Krücken, R; Kühn, W; Kugler, A; Kurepin, A; Kurilkin, A; Kurilkin, P; Ladygin, V; Lang, S; Lange, J S; Lapidus, K; Liu, T; Lopes, L; Lorenz, M; Maier, L; Mangiarotti, A; Markert, J; Metag, V; Michalska, B; Michel, J; Morinière, E; Mousa, J; Müntz, C; Naumann, L; Otwinowski, J; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Pietraszko, J; Przygoda, W; Ramstein, B; Reshetin, A; Rustamov, A; Sadovsky, A; Salabura, P; Schmah, A; Schwab, E; Sobolev, Yu G; Spataro, S; Spruck, B; Ströbele, H; Stroth, J; Sturm, C; Tarantola, A; Teilab, K; Tlusty, P; Traxler, M; Trebacz, R; Tsertos, H; Wagner, V; Vasiliev, T; Weber, M; Wisniowski, M; Wojcik, T; Wüstenfeld, J; Yurevich, S; Zanevsky, Y; Zhou, P

    2015-01-01

    The tagged quasi-free $np \\to np\\pi^+\\pi^-$ reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon ($\\sqrt s \\sim$ 2.42 GeV/c for the quasi-free collision). For the first time, differential distributions for $\\pi^{+}\\pi^{-}$ production in $np$ collisions have been collected in the region corresponding to the large transverse momenta of the secondary particles. The invariant mass and angular distributions for the $np\\rightarrow np\\pi^{+}\\pi^{-}$ reaction are compared with different models. This comparison confirms the dominance of the $t$-channel with $\\Delta\\Delta$ contribution. It also validates the changes previously introduced in the Valencia model to describe two-pion production data in other isospin channels, although some deviations are observed, especially for the $\\pi^{+}\\pi^{-}$ invariant mass spectrum. The extracted total cross section is also in much better agreement with this model. Our new me...

  8. Differential cross section and analysing power of the quasi-free pn -> {pp}_s pi- reaction at 353 MeV

    CERN Document Server

    Dymov, S; Barsov, S; Baru, V; Benati, P; Bertelli, S; Chiladze, D; Dzyuba, A; Gebel, R; Goslawski, P; Guidoboni, G; Hanhart, C; Hartmann, M; Kacharava, A; Khoukaz, A; Komarov, V; Kulessa, P; Kulikov, A; Kurbatov, V; Lenisa, P; Lensky, V; Lomidze, N; Lorentz, B; Macharashvili, G; Mielke, M; Mikirtytchiants, S; Merzliakov, S; Ohm, H; Papenbrock, M; Rathmann, F; Serdyuk, V; Shmakova, V; Stroeher, H; Tabidze, M; Tsirkov, D; Trusov, S; Uzikov, Yu; Valdau, Yu; Wilkin, C

    2011-01-01

    In order to establish links between p-wave pion production in nucleon-nucleon collisions and low energy three-nucleon scattering, an extensive programme of experiments on pion production is currently underway at COSY-ANKE. The final proton pair is measured at very low excitation energy, leading to an S-wave diproton, denoted here as {pp}_s. By using a deuterium target we have obtained data on the differential cross section and analysing power of the quasi-free pol{p}n -> {pp}_s pi^- reaction at 353 MeV. The spectator proton p_sp was either measured directly in silicon tracking telescopes or reconstructed using the momentum of a detected pi^-. Both observables can be described in terms of s-, p-, and d-wave pion production amplitudes. Taken together with the analogous data on the pol{p}p -> {pp}_s pi^0 reaction, full partial wave decompositions of both processes were carried out.

  9. A three-body model for the analysis of quasi-free scattering reactions in inverse kinematics

    CERN Document Server

    Moro, Antonio M

    2015-01-01

    A new method to calculate cross sections for $(p,pn)$ and $(p,2p)$ reactions measured under inverse kinematics conditions is proposed. The method uses the prior form of the scattering transition amplitude, and replaces the exact three-body wave function appearing in this expression by an expansion in terms of $p$-$n$ or $p$-$p$ states, covering the physically relevant excitation energies and partial waves. A procedure of discretization, similar to that used in continuum-discretized coupled-channels calculations, is applied in order to make this expansion finite and numerically tractable. The proposed formalism is non-relativistic but several relativistic kinematical corrections are applied to extend its applicability to energies of current interest. The underlying optical potentials for the entrance and exit channels are generated microscopically, by folding an effective density-dependent G-matrix with the density of the composite nucleus. Numerical calculations for $^{12}$C($p$,$2p$), $^{12}$C($p$,$pn$) and ...

  10. Quasi-free elastic deuteron-proton scattering in the three-body break-up reaction of deuteron-deuteron scattering

    Science.gov (United States)

    Ramazani-Moghaddam-Arani, A.; Amir-Ahmadi, H. R.; Bacher, A. D.; Bailey, C. D.; Biegun, A.; Eslami-Kalantari, M.; Gašparić, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Micherdzinska, A. M.; Moeini, H.; Shende, S. V.; Stephan, E.; Stephenson, E. J.; Sworst, R.

    2011-05-01

    This paper discusses some of the recent results obtained in a deuteron-deuteron scattering experiment using a polarized beam of deuterons with an incident energy of 130 MeV. A 4π detection system allowed to measure cross sections and spin observables for various final-state configurations. Here, we discuss the quasi-free elastic deuteron-proton scattering process in deuteron-deuteron scattering which has been observed by analyzing kinematical configurations for which the target neutron acts as a spectator particle. This part of the data can be compared directly to three-nucleon calculations and with existing data for the elastic deuteron-proton scattering process. The results for the polarization observables iT11 and T22 agree well with elastic scattering data published so-far and measured concurrently using a proton target. Surprisingly, the tensor observable T20 shows significant discrepancies with data taken using a proton target.

  11. Measurement of the quasi free np → npπ+π− and np → ppπ−π0 reactions at 1.25 GeV With HADES

    Directory of Open Access Journals (Sweden)

    Kurilkin A.

    2014-01-01

    Full Text Available We present the results of two-pion production in tagged quasi-free np collisions at a deutron incident beam energy of 1.25 GeV/c measured with the High-Acceptance Di-Electron Spectrometer (HADES installed at GSI. The specific acceptance of HADES allowed for the first time to obtain high-precision data on π+π− and π−π0 production in np collisions in a region corresponding to large transverse momenta of the secondary particles. The obtained differential cross section data provide strong constraints on the production mechanisms and on the various baryon resonance contributions (∆∆, N(1440, N(1520, ∆(1600. The invariant mass and angular distributions from the np → npπ+π −and np → ppπ−π0 reactions are compared with different theoretical model predictions.

  12. Measurement of the quasi free np → npπ+π- and np → ppπ-π0 reactions at 1.25 GeV With HADES

    Science.gov (United States)

    Kurilkin, A.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Belyaev, A.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Deveaux, C.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gill, K.; Golubeva, M.; González-Díaz, D.; Guber, F.; Gumberidze, M.; Harabasz, S.; Hennino, T.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Kardan, K.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Krása, A.; Krebs, E.; Krizek, F.; Kuc, H.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lang, S.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Pechenov, V.; Pechenova, O.; Petousis, V.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Rehnisch, L.; Reshetin, A.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmidt-Sommerfeld, K.; Schuldes, H.; Sellheim, P.; Siebenson, J.; Silva, L.; Sobolev, Yu. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Wendisch, C.; Wirth, J.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y.

    2014-11-01

    We present the results of two-pion production in tagged quasi-free np collisions at a deutron incident beam energy of 1.25 GeV/c measured with the High-Acceptance Di-Electron Spectrometer (HADES) installed at GSI. The specific acceptance of HADES allowed for the first time to obtain high-precision data on π+π- and π-π0 production in np collisions in a region corresponding to large transverse momenta of the secondary particles. The obtained differential cross section data provide strong constraints on the production mechanisms and on the various baryon resonance contributions (∆∆, N(1440), N(1520), ∆(1600)). The invariant mass and angular distributions from the np → npπ+π -and np → ppπ-π0 reactions are compared with different theoretical model predictions.

  13. Investigation of the quasi-free reaction p+d → d+η+p{sub sp} close to threshold at ANKE

    Energy Technology Data Exchange (ETDEWEB)

    Schroeer, Daniel; Fritzsch, Christopher; Khoukaz, Alfons; Mielke, Malte; Papenbrock, Michael; Taeschner, Alexander [Institut fuer Kernphysik, Westfaelische Wilhelms-Universitaet, Muenster (Germany); Collaboration: ANKE-Collaboration

    2014-07-01

    Recent precision measurements on the interaction of η mesons with He nuclei have shown evidence for an unexpectedly strong final state interaction which could possibly lead to the formation of η-mesic nuclei. To further investigate this behaviour for different nuclei a measurement on the reaction p+d → d+η+p{sub sp} has been performed at the ANKE experiment located at the COSY accelerator of the Forschungszentrum Juelich. Here the deuteron serves as an effective neutron target while the remaining proton acts in good approximation as a spectator particle.The chosen beam momenta (p{sub 1} = 2.09 GeV/c and p{sub 2} = 2.25 GeV/c) in combination with the Fermi motion of the nucleons inside of the deuteron allow to measure cross sections in an excess energy range from 0 MeV up to 100 MeV. Based on these information the dη scattering length a{sub d}η will be measured which will shed new light on the interaction between η meson and nucleons. In addition the data obtained at higher excess energies will allow for further information about the role of nucleonic resonances on the η meson production. Recent results are presented and discussed.

  14. Quasi-free photoproduction of eta-mesons of the neutron

    CERN Document Server

    Jaegle, I; Anisovich, A V; Bacelar, J C S; Bantes, B; Bartholomy, O; Bayadilov, D; Beck, R; Beloglasov, Yu A; Castelijns, R; Credé, V; Dutz, H; Ehmanns, A; Elsner, D; Essig, K; Ewald, R; Fabry, I; Fuchs, M; Funke, C; Gothe, R; Gregor, R; Gridnev, A B; Gutz, E; Hoeffgen, S; Hoffmeister, P; Horn, I; Junkersfeld, J; Kalinowsky, H; Kammer, S; Kleber, V; Klein, Frank; Klein, Friedrich; Klempt, E; Konrad, M; Kotulla, M; Krusche, B; Lang, M; Langheinrich, J; Löhner, H; Lopatin, I V; Lotz, J; Lugert, S; Menze, D; Messchendorp, J G; Metag, V; Morales, C; Nanova, M; Nikonov, V A; Novinski, D V; Novotny, R; Ostrick, M; Pant, L M; Van Pee, H; Pfeiffer, M; Radkov, A K; Roy, A; Sarantsev, A V; Schadmand, S; Schmidt, C; Schmieden, H; Schoch, B; Shende, S; Sokhoyan, V; Suele, A; Sumachev, V V; Szczepanek, T; Thoma, U; Trnka, D; Varma, R; Walther, D; Weinheimer, C; Wendel, C

    2008-01-01

    Quasi-free photoproduction of eta-mesons off nucleons bound in the deuteron has been measured with the CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at the Bonn ELSA accelerator. The eta-mesons have been detected in coincidence with recoil protons and recoil neutrons, which allows a detailed comparison of the quasi-free n(gamma,eta)n and p(gamma,eta)p reactions. The excitation function for eta-production off the neutron shows a pronounced bump-like structure at W=1.68 GeV (E_g ~ 1 GeV), which is absent for the proton.

  15. Electron-phonon coupling in quasi free-standing graphene

    DEFF Research Database (Denmark)

    Christian Johannsen, Jens; Ulstrup, Søren; Bianchi, Marco

    2013-01-01

    Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many......-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both...

  16. Electron-phonon coupling in quasi free-standing graphene

    DEFF Research Database (Denmark)

    Christian Johannsen, Jens; Ulstrup, Søren; Bianchi, Marco;

    2013-01-01

    Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many......-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both...

  17. Spin observables in the three-body break-up process near the quasi-free limit in deuteron-deuteron scattering

    Science.gov (United States)

    Ramazani-Moghaddam-Arani, A.; Mahjour-Shafiei, M.; Amir-Ahmadi, H. R.; Bacher, A. D.; Bailey, C. D.; Biegun, A.; Eslami-Kalantari, M.; Gašparić, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Micherdzinska, A. M.; Moeini, H.; Shende, S. V.; Stephan, E.; Stephenson, E. J.; Sworst, R.

    2013-10-01

    We have studied spin observables in the three-body break-up reaction in deuteron-deuteron scattering in the phase-space regime that corresponds to the quasi-free deuteron-proton scattering process with the neutron as spectator. The data are compared to measurements of the elastic deuteron-proton scattering process and state-of-the-art Faddeev calculations. The results for iT11 and T22 for the quasi-free scattering data agree very well with previously published elastic-scattering data. A significant discrepancy is found for T20, which could point to a break-down of the quasi-free assumption.

  18. Quasi-free photoproduction of {eta}-mesons off the deuteron

    Energy Technology Data Exchange (ETDEWEB)

    Jaegle, I.; Krusche, B.; Dieterle, M.; Keshelashvili, I.; Kotulla, M.; Maghrbi, Y.; Mertens, T.; Oberle, M.; Pheron, F.; Werthmueller, D.; Witthauer, L. [Univ. Basel (Switzerland). Dept. Physik; Anisovich, A.V.; Bayadilov, D.E.; Nikonov, V.A.; Novinski, D.V.; Sarantsev, A.V. [Helmholtz-Inst. fuer Strahlen- und Kernphysik der Univ. Bonn (Germany); Petersburg Nuclear Physics Inst., Gatchina (Russian Federation); Bacelar, J.C.S.; Castelijns, R.; Loehner, H.; Messchendorp, J.G. [Univ. of Groningen, KVI, Groningen (Netherlands); Bantes, B.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Hillert, W.; Hoeffgen, S.; Kammer, S.; Kleber, V.; Klein, Frank; Klein, Friedrich; Konrad, M.; Menze, D.; Schmieden, H.; Schoch, B.; Suele, A.; Walther, D. [Physikalisches Inst. der Universitaet Bonn (Germany); Bartholomy, O.; Beck, R.; Funke, C.; Gutz, E.; Hoffmeister, P.; Horn, I.; Junkersfeld, J.; Kalinowsky, H.; Klempt, E.; Lang, M.; Schmidt, C.; Sokhoyan, V.; Szczepanek, T.; Wendel, C. [Helmholtz-Inst. fuer Strahlen- und Kernphysik der Univ. Bonn (Germany); Beloglazov, Y.A.; Gridnev, A.B.; Lopatin, I.V.; Sumachev, V.V. [Petersburg Nuclear Physics Inst., Gatchina (Russian Federation); Crede, V. [Florida State Univ., Dept. of Physics, Tallahassee, FL (United States); Gothe, R. [Physikalisches Inst. der Univ. Bonn (Germany); Univ. of South Carolina (United States); Gregor, R.; Lugert, S.; Metag, V.; Nanova, M.; Novotny, R.; Pfeiffer, M.; Trnka, D. [Univ. Giessen, II. Physikalisches Inst., Giessen (Germany); Ostrick, M. [Physikalisches Inst. der Univ. Bonn (Germany); University of Mainz (Germany); Pant, L.M. [Univ. Giessen, II. Physikalisches Inst., Giessen (Germany); BARC, Nuclear Physics Div., Mumbai (India); Pee, H. van; Thoma, U. [Helmholtz-Inst. fuer Strahlen- und Kernphysik der Univ. Bonn (Germany); Univ. Giessen (Germany); Roy, A.; Varma, R. [Univ. Giessen (Germany); Indian Inst. of Technology, Mumbai (India). Dept. of Physics] [and others

    2011-08-15

    Precise data for quasi-free photoproduction of {eta}-mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5GeV. The {eta}-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to {eta}-production off the free proton. No significant effects beyond the folding of the free cross-section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the {eta}-nucleon pairs reconstructed from the final-state four-momenta of the particles. The total cross-section for quasi-free {eta}-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1GeV of incident photon energy, which is not observed for the proton. This structure is even narrower in the invariant-mass spectrum of the {eta}-neutron pairs. Position and width of the peak in the invariant-mass spectrum are W {approx} 1665 MeV and FWHM {gamma} {approx} 25 MeV. The data are compared to the results of different models. (orig.)

  19. Quasi-free photoproduction of eta-mesons off the deuteron

    CERN Document Server

    Jaegle, I; Anisovich, A V; Bacelar, J C S; Bantes, B; Bartholomy, O; Bayadilov, D E; Beck, R; Beloglazov, Y A; Castelijns, R; Crede, V; Dieterle, M; Dutz, H; Elsner, D; Ewald, R; Frommberger, F; Funke, C; Gothe, R; Gregor, R; Gridnev, A B; Gutz, E; Hillert, W; Hoeffgen, S; Hoffmeister, P; Horn, I; Junkersfeld, J; Kalinowsky, H; Kammer, S; Keshelashvili, I; Kleber, V; Klein, Frank; Klein, Friedrich; Klempt, E; Konrad, M; Kotulla, M; Lang, M; Loehner, H; Lopatin, I V; Lugert, S; Maghrbi, Y; Menze, D; Mertens, T; Messchendorp, J G; Metag, V; Nikonov, V A; Nanova, M; Novinski, D V; Novotny, R; Oberle, M; Ostrick, M; Pant, L M; van Pee, H; Pfeiffer, M; Pheron, F; Roy, A; Sarantsev, A V; Schadmand, S; Schmidt, C; Schmieden, H; Schoch, B; Shende, S V; Sokhoyan, V; Suele, A; Sumachev, V V; Szczepanek, T; Thoma, U; Trnka, D; Varma, R; Walther, D; Wendel, C; Werthmueller, D; Witthauer, L

    2011-01-01

    Precise data for quasi-free photoproduction of $\\eta$ mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5 GeV. The $\\eta$-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to $\\eta$-production off the free proton. No significant effects beyond the folding of the free cross section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the $\\eta$-nucleon pairs reconstructed from the final state four-momenta of the particles. The total cross section for quasi-free $\\eta$-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1 GeV of incident photon energy, which is not observed for...

  20. Quasi-free Compton Scattering and the Polarizabilities of the Neutron

    CERN Document Server

    Kossert, K; Wissmann, F; Ahrens, J; Annand, J R M; Arends, H J; Beck, R; Caselotti, G; Grabmayr, P; Jahn, O; Jennewein, P; Levchuk, M I; Lvov, A I; McGeorge, J C; Natter, A; Olmos de Léon, V; Petrunkin, V A; Rosner, G; Schumacher, M; Seitz, B; Smend, F; Thomas, A; Weihofen, W; Zapadtka, F

    2003-01-01

    Differential cross sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48 cm $\\oslash$ $\\times$ 64 cm NaI(Tl) photon detector and the G\\"ottingen SENECA recoil detector. The data cover photon energies ranging from 200 MeV to 400 MeV at $\\theta^{LAB}_\\gamma=136.2^\\circ$. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction $p(\\gamma,\\pi^+ n)$. The "free" proton Compton scattering cross sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross section for free scattering from quasi-free data. Differential cross sections on the free neutron have been extracted and the difference of the electroma...

  1. Neutron-antineutron oscillations beyond the quasi-free limit

    CERN Document Server

    Davis, E David

    2016-01-01

    Prompted by plans to conduct a new neutron oscillation experiment at the European Spallation Source (ESS), we consider issues associated with the magnetic field that must be present, some of which are potentially exacerbated by the significantly larger length $l$ contemplated for the neutron propagation region. To this end, we introduce a stochastic model of the residual magnetic field within the propagation region which draws on features of magnetic profiles measured during the last free neutron oscillation experiment [conducted at the Institut Laue-Langevin (ILL) in the 1990's]. We average over both fluctuations in the magnetic field sampled by neutrons, and representative spectra of neutron speeds. We find that deviations from the quasi-free result for the antineutron probability do not depend quadratically on $l$ (as a naive perturbative estimate would suggest) but increase only linearly with $l$. As regards the large spikes in the magnetic field which can be expected at, for example, joints in the magnet...

  2. Spin observables in the three-body break-up process near the quasi-free limit in deuteron–deuteron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ramazani-Moghaddam-Arani, A., E-mail: ramazani@kvi.nl [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); KVI, University of Groningen, Groningen (Netherlands); Mahjour-Shafiei, M. [Department of Physics, University of Tehran, Tehran 1439955961 (Iran, Islamic Republic of); KVI, University of Groningen, Groningen (Netherlands); Amir-Ahmadi, H.R. [KVI, University of Groningen, Groningen (Netherlands); Bacher, A.D.; Bailey, C.D. [Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN (United States); Biegun, A. [KVI, University of Groningen, Groningen (Netherlands); Eslami-Kalantari, M. [KVI, University of Groningen, Groningen (Netherlands); Department of Physics, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of); Gašparić, I. [Rudjer Bošković Institute, Zagreb (Croatia); Joulaeizadeh, L.; Kalantar-Nayestanaki, N. [KVI, University of Groningen, Groningen (Netherlands); Kistryn, St. [Institute of Physics, Jagellonian University, Krakow (Poland); Kozela, A. [University of Winnipeg, Winnipeg (Canada); Mardanpour, H.; Messchendorp, J.G. [KVI, University of Groningen, Groningen (Netherlands); Micherdzinska, A.M. [Institute of Nuclear Physics PAN, Krakow (Poland); Moeini, H.; Shende, S.V. [KVI, University of Groningen, Groningen (Netherlands); Stephan, E. [Institute of Physics, University of Silesia, Katowice (Poland); Stephenson, E.J. [Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN (United States); Sworst, R. [Institute of Physics, Jagellonian University, Krakow (Poland)

    2013-10-01

    We have studied spin observables in the three-body break-up reaction in deuteron–deuteron scattering in the phase-space regime that corresponds to the quasi-free deuteron–proton scattering process with the neutron as spectator. The data are compared to measurements of the elastic deuteron–proton scattering process and state-of-the-art Faddeev calculations. The results for iT{sub 11} and T{sub 22} for the quasi-free scattering data agree very well with previously published elastic-scattering data. A significant discrepancy is found for T{sub 20}, which could point to a break-down of the quasi-free assumption.

  3. Spin observables in the three-body break-up process near the quasi-free limit in deuteron-deuteron scattering

    NARCIS (Netherlands)

    Ramazani-Moghaddam-Arani, A.; Mahjour-Shafiei, M.; Amir-Ahmadi, H. R.; Bacher, A. D.; Bailey, C. D.; Biegun, A.; Eslami-Kalantari, M.; Gasparic, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; St Kistryn, [No Value; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Micherdzinska, A. M.; Moeini, H.; Shende, S. V.; Stephan, E.; Stephenson, E. J.; Sworst, R.

    2013-01-01

    We have studied spin observables in the three-body break-up reaction in deuteron-deuteron scattering in the phase-space regime that corresponds to the quasi-free deuteron-proton scattering process with the neutron as spectator. The data are compared to measurements of the elastic deuteron-proton sca

  4. Quasi-free $\\pi^0$ Photoproduction from the Bound Nucleon

    CERN Document Server

    Kossert, K; Wissmann, F; Ahrens, J; Annand, J R M; Arends, H J; Beck, R; Caselotti, G; Grabmayr, P; Jahn, O; Jennewein, P; Levchuk, M I; Lvov, A I; McGeorge, J C; Natter, A; Olmos de Léon, V; Petrunkin, V A; Rosner, G; Schumacher, M; Seitz, B; Smend, F; Thomas, A; Weihofen, W; Zapadtka, F

    2004-01-01

    Differential cross-sections for quasi-free $\\pi^0$ photoproduction from the proton and neutron bound in the deuteron have been measured for $E_\\gamma= 200 - 400$ MeV at $\\theta^{\\rm lab}_\\gamma = 136.2^\\circ$ usind the Glasgow photon tagger at MAMI, the Mainz 48 cm $\\varnothing$ $\\times$ 64 cm NaI(Tl) photon detector and the G\\"ottingen SENECA recoil detector. For the proton measurements made with both liquid deuterium and liquid hydrogen targets allow direct comparison of "free" $\\pi^0$ photoproduction cross-sections as extracted from the bound proton data with experimental free cross sections which are found to be in reasonable agreement below 320 MeV. At higher energies the "free" cross sections extracted from quasifree data are significantly smaller than the experimental free cross sections and theoretical predictions based on multipole analysis. For the first time, "free" neutron cross sections have been extracted in the $\\Delta$-region. They are also in agreement with the predictions from multipole anal...

  5. Quasi-free photoproduction of pion-pairs off protons and neutrons

    CERN Document Server

    Oberle, M

    2014-01-01

    Beam-helicity asymmetries and mass-differential cross sections have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral and mixed-charge pion pairs in the reactions $\\boldsymbol{\\gamma}p\\rightarrow n\\pi^0\\pi^+$ and $\\boldsymbol{\\gamma}p\\rightarrow p\\pi^0\\pi^0$ off free protons and $\\boldsymbol{\\gamma}d \\rightarrow (p)p\\pi^0\\pi^-$, $\\boldsymbol{\\gamma}d\\rightarrow (n)p\\pi^0\\pi^0$ and $\\boldsymbol{\\gamma}d\\rightarrow (n)n\\pi^0\\pi^+$, $\\boldsymbol{\\gamma}d\\rightarrow (p)n \\pi^0\\pi^0$ off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced in bremsstrahlung processes of longitudinally polarized electrons and tagged with the Glasgow-Mainz magnetic spectrometer. The decay products (photons, protons, neutrons, and charged pions) were detected in the $4\\pi$ electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. Using a full kinematic reconstruction of the final state, excellent agreement wa...

  6. Quasi-free photoproduction of {eta}-mesons off {sup 3}He nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Witthauer, L.; Werthmueller, D.; Keshelashvili, I.; Dieterle, M.; Jaegle, I.; Kaeser, A.; Krusche, B.; Maghrbi, Y.; Oberle, M.; Pheron, F.; Rostomyan, T. [University of Basel, Department of Physics, Basel (Switzerland); Aguar-Bartolome, P.; Ahrens, J.; Arends, H.J.; Heid, E.; Jahn, O.; Martinez, M.; Ostrick, M.; Rost, M.; Thomas, A. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); Annand, J.R.M.; Hamilton, D.; Howdle, D.; Livingston, K.; MacGregor, I.J.D.; Mancell, J.; McGeorge, J.C.; McNicoll, E.; Robinson, J.; Rosner, G. [University of Glasgow, School of Physics and Astronomy, Glasgow (United Kingdom); Bantawa, K.; Manley, D.M. [Kent State University, Kent, Ohio (United States); Beck, R.; Nikolaev, A.; Schumann, S.; Unverzagt, M. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); University of Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Bekrenev, V.; Kruglov, S.P.; Kulbardis, A. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Braghieri, A.; Mushkarenkov, A.; Pedroni, P. [INFN, Pavia (Italy); Branford, D.; Glazier, D.I.; Jude, T.C.; Sikora, M.H.; Watts, D.P. [University of Edinburgh, School of Physics, Edinburgh (United Kingdom); Briscoe, W.J.; Demissie, B.; Marinides, Z. [The George Washington University, Institute for Nuclear Studies, Washington, DC (United States); Brudvik, J.; Nefkens, B.M.K.; Starostin, A. [University of California Los Angeles, Los Angeles, California (United States); Cherepnya, S.; Fil' kov, L.V. [Lebedev Physical Institute, Moscow (Russian Federation); Downie, E.J. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); University of Glasgow, School of Physics and Astronomy, Glasgow (United Kingdom); The George Washington University, Institute for Nuclear Studies, Washington, DC (United States); Drexler, P.; Metag, V.; Novotny, R. [University of Giessen, II. Physikalisches Institut, Giessen (Germany); Fix, A. [Tomsk Polytechnic University, Laboratory of Mathematical Physics, Tomsk (Russian Federation); Hornidge, D.; Middleton, D.G. [Mount Allison University, Sackville (Canada); Huber, G.M. [University of Regina, Regina (Canada); Kashevarov, V.L. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); Lebedev Physical Institute, Moscow (Russian Federation); Kondratiev, R.; Lisin, V.; Polonski, A. [Institute for Nuclear Research, Moscow (Russian Federation); Korolija, M.; Supek, I. [Rudjer Boskovic Institute, Zagreb (Croatia); Oussena, B. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); The George Washington University, Institute for Nuclear Studies, Washington, DC (United States); Prakhov, S. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); The George Washington University, Institute for Nuclear Studies, Washington, DC (United States); University of California Los Angeles, Los Angeles, California (United States); Sober, D. [The Catholic University of America, Washington, DC (United States); Thiel, M. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); University of Giessen, II. Physikalisches Institut, Giessen (Germany); Collaboration: Crystal Ball/TAPS experiment at MAMI, the A2 Collaboration

    2013-12-15

    Quasi-free photoproduction of {eta}-mesons has been measured off nucleons bound in {sup 3}He nuclei for incident photon energies from the threshold region up to 1.4 GeV. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with an almost 4{pi} covering electromagnetic calorimeter, combining the TAPS and Crystal Ball detectors. The {eta}-mesons were detected in coincidence with the recoil nucleons. This allowed a comparison of the production cross section off quasi-free protons and quasi-free neutrons and a full kinematic reconstruction of the final state, eliminating effects from nuclear Fermi motion. In the S{sub 11}(1535) resonance peak, the data agree with the neutron/proton cross section ratio extracted from measurements with deuteron targets. More importantly, the prominent structure observed in photoproduction off quasi-free neutrons bound in the deuteron is also clearly observed. Its parameters (width, strength) are consistent with the expectations from the deuteron results. On an absolute scale the cross sections for both quasi-free protons and neutrons are suppressed with respect to the deuteron target pointing to significant nuclear final-state interaction effects. (orig.)

  7. The evidence of quasi-free positronium state in GiPS-AMOC spectra of glycerol

    CERN Document Server

    Zvezhinskiy, D; Wagner, A; Krause-Rehberg, R; Stepanov, S V

    2013-01-01

    We present the results of processing of Age-Momentum Correlation (AMOC) spectra that were measured for glycerol by the Gamma-induced positron spectroscopy (GiPS) facility. Our research has shown that the shape of experimental s(t) curve cannot be explained without introduction of the intermediate state of positronium (Ps), called quasi-free Ps. This state yields the wide Doppler line near zero lifetimes. We discuss the possible properties of this intermediate Ps state from the viewpoint of developed model. The amount of annihilation events produced by quasi-free Ps is estimated to be less than 5% of total annihilations. In the proposed model, quasi-free Ps serves as a precursor for trapped Ps of para- and ortho-states.

  8. Quasi-free photoproduction of eta-mesons off 3He nuclei

    CERN Document Server

    Witthauer, L; Keshelashvili, I; Aguar-Bartolome, P; Ahrens, J; Annand, J R M; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Demissie, B; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Glazier, D I; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Huber, G M; Jaegle, I; Jahn, O; Jude, T C; Kaeser, A; Kashevarov, V L; Kondratiev, R; Korolija, M; Kruglov, S P; Krusche, B; Kulbardis, A; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McNicoll, E; Metag, V; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S; Robinson, J; Rosner, G; Rost, M; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D; Starostin, A; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P

    2013-01-01

    Quasi-free photoproduction of $\\eta$-mesons has been measured off nucleons bound in $^3$He nuclei for incident photon energies from the threshold region up to 1.4 GeV. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with an almost $4\\pi$ covering electromagnetic calorimeter, combining the TAPS and Crystal Ball detectors. The $\\eta$-mesons were detected in coincidence with the recoil nucleons. This allowed a comparison of the production cross section off quasi-free protons and quasi-free neutrons and a full kinematic reconstruction of the final state, eliminating effects from nuclear Fermi motion. In the $S_{11}$(1535) resonance peak, the data agree with the neutron/proton cross section ratio extracted from measurements with deuteron targets. More importantly, the prominent structure observed in photoproduction off quasi-free neutrons bound in the deuteron is also clearly observed. Its parameters (width, strength) are consistent with the expectations from the deuteron r...

  9. Quasi-free photoproduction of eta-mesons off the deuteron

    NARCIS (Netherlands)

    Jaegle, I.; Krusche, B.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, B.; Bartholomy, O.; Bayadilov, D. E.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Crede, V.; Dieterle, M.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Funke, C.; Gothe, R.; Gregor, R.; Gridnev, A. B.; Gutz, E.; Hillert, W.; Hoeffgen, S.; Hoffmeister, P.; Horn, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Keshelashvili, I.; Kleber, V.; Klein, Frank; Klein, Friedrich; Klempt, E.; Konrad, M.; Kotulla, M.; Lang, M.; Löhner, H.; Lopatin, I. V.; Lugert, S.; Maghrbi, Y.; Menze, D.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nikonov, V. A.; Nanova, M.; Novinski, D. V.; Novotny, R.; Oberle, M.; Ostrick, M.; Pant, L. M.; van Pee, H.; Pfeiffer, M.; Pheron, F.; Roy, A.; Sarantsev, A. V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Shende, S. V.; Sokhoyan, V.; Suele, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Wendel, C.; Werthmueller, D.; Witthauer, L.

    2011-01-01

    Precise data for quasi-free photoproduction of eta-mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5 GeV. The eta-mesons have been detected in coincidence with recoil protons and neutrons. Pos

  10. Formation of quasi-free and bubble positronium states in water and aqueous solutions

    CERN Document Server

    Stepanov, Serge V; Byakov, Vsevolod M; Zvezhinskiy, D S; Subrahmanyam, V S

    2013-01-01

    It is shown that in aqueous solutions a positronium atom is first formed in the quasi-free state, and, after 50-100 ps, becomes localized in a nanobubble. Analysis of the annihilation spectra of NaNO3 aqueous solutions shows that the hydrated electron is not involved in the positronium (Ps) formation.

  11. Quasi free-standing silicene in a superlattice with hexagonal boron nitride

    KAUST Repository

    Kaloni, T. P.

    2013-11-12

    We study a superlattice of silicene and hexagonal boron nitride by first principles calculations and demonstrate that the interaction between the layers of the superlattice is very small. As a consequence, quasi free-standing silicene is realized in this superlattice. In particular, the Dirac cone of silicene is preserved. Due to the wide band gap of hexagonal boron nitride, the superlattice realizes the characteristic physical phenomena of free-standing silicene. In particular, we address by model calculations the combined effect of the intrinsic spin-orbit coupling and an external electric field, which induces a transition from a semimetal to a topological insulator and further to a band insulator.

  12. $^{11}$Be($\\beta$p), a quasi-free neutron decay?

    CERN Document Server

    Riisager, K.; Borge, M.J.G.; Briz, J.A.; Carmona-Gallardo, M.; Fraile, L.M.; Fynbo, H.O.U.; Giles, T.; Gottberg, A.; Heinz, A.; Johansen, J.G.; Jonson, B.; Kurcewicz, J.; Lund, M.V.; Nilsson, T.; Nyman, G.; Rapisarda, E.; Steier, P.; Tengblad, O.; Thies, R.; Winkler, S.R.

    2014-01-01

    We have observed $\\beta$-delayed proton emission from the neutron-rich nucleus $^{11}$Be by analysing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.4 $\\pm$ 0.6)$\\times$ 10$^{-6}$ the strength of this decay mode, as measured by the B$_\\mathrm{GT}$-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the $^{11}$Be halo neutron into a single-proton state.

  13. $^{11}$Be($\\beta$p), a quasi-free neutron decay?

    CERN Document Server

    Riisager, K.; Borge, M.J.G.; Briz, J.A.; Carmona-Gallardo, M.; Fraile, L.M.; Fynbo, H.O.U.; Giles, T.; Gottberg, A.; Heinz, A.; Johansen, J.G.; Jonson, B.; Kurcewicz, J.; Lund, M.V.; Nilsson, T.; Nyman, G.; Rapisarda, E.; Steier, P.; Tengblad, O.; Thies, R.; Winkler, S.R.

    2014-01-01

    We have observed $\\beta$-delayed proton emission from the neutron-rich nucleus $^{11}$Be by analysing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.4 $\\pm$ 0.6)$\\times$ 10$^{-6}$ the strength of this decay mode, as measured by the B$_\\mathrm{GT}$-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the $^{11}$Be halo neutron into a single-proton state.

  14. {sup 11}Be(βp), a quasi-free neutron decay?

    Energy Technology Data Exchange (ETDEWEB)

    Riisager, K., E-mail: kvr@phys.au.dk [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Forstner, O. [Faculty of Physics, University of Vienna, Währinger Strasse 17, A-1090 Wien (Austria); Stefan-Meyer-Institut für subatomare Physik, Austrian Academy of Sciences, A-1090 Wien (Austria); Borge, M.J.G. [ISOLDE, PH Department, CERN, CH-1211 Geneve 23 (Switzerland); Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Briz, J.A.; Carmona-Gallardo, M. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Fraile, L.M. [Grupo de Física Nuclear, Universidad Complutense de Madrid, CEI Moncloa, E-28040 Madrid (Spain); Fynbo, H.O.U. [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Giles, T. [EN Department, CERN, CH-1211 Geneve 23 (Switzerland); Gottberg, A. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); EN Department, CERN, CH-1211 Geneve 23 (Switzerland); Heinz, A. [Fundamental Fysik, Chalmers Tekniska Högskola, SE-41296 Göteborg (Sweden); Johansen, J.G. [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Jonson, B. [Fundamental Fysik, Chalmers Tekniska Högskola, SE-41296 Göteborg (Sweden); Kurcewicz, J. [ISOLDE, PH Department, CERN, CH-1211 Geneve 23 (Switzerland); Lund, M.V. [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Nilsson, T.; Nyman, G. [Fundamental Fysik, Chalmers Tekniska Högskola, SE-41296 Göteborg (Sweden); Rapisarda, E. [ISOLDE, PH Department, CERN, CH-1211 Geneve 23 (Switzerland); and others

    2014-05-01

    We have observed β{sup −}-delayed proton emission from the neutron-rich nucleus {sup 11}Be by analyzing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.3±0.9)⋅10{sup −6} the strength of this decay mode, as measured by the B{sub GT}-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the {sup 11}Be halo neutron into a single-proton state.

  15. Quasi-free-standing bilayer epitaxial graphene field-effect transistors on 4H-SiC (0001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yu, C.; Li, J.; Song, X. B.; Liu, Q. B.; Cai, S. J.; Feng, Z. H., E-mail: ga917vv@163.com [National Key Laboratory of ASIC, Hebei Semiconductor Research Institute, Shijiazhuang 050051 (China); He, Z. Z. [National Key Laboratory of ASIC, Hebei Semiconductor Research Institute, Shijiazhuang 050051 (China); School of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2016-01-04

    Quasi-free-standing epitaxial graphene grown on wide band gap semiconductor SiC demonstrates high carrier mobility and good material uniformity, which make it promising for graphene-based electronic devices. In this work, quasi-free-standing bilayer epitaxial graphene is prepared and its transistors with gate lengths of 100 nm and 200 nm are fabricated and characterized. The 100 nm gate length graphene transistor shows improved DC and RF performances including a maximum current density I{sub ds} of 4.2 A/mm, and a peak transconductance g{sub m} of 2880 mS/mm. Intrinsic current-gain cutoff frequency f{sub T} of 407 GHz is obtained. The exciting DC and RF performances obtained in the quasi-free-standing bilayer epitaxial graphene transistor show the great application potential of this material system.

  16. Gauge-Invariant Quasi-Free States on the Algebra of the Anyon Commutation Relations

    Science.gov (United States)

    Lytvynov, Eugene

    2017-04-01

    Let X=R^2 and let qin{C}, |q|=1. For x=(x^1,x^2) and y=(y^1,y^2) from X^2, we define a function Q(x,y) to be equal to q if x1 y1, and to Rq if x^1=y^1. Let partial_x^+, partial_x^- (xin X) be operator-valued distributions such that partial_x^+ is the adjoint of partial_x^-. We say that partial_x^+, partial_x^- satisfy the anyon commutation relations (ACR) if partial^+_xpartial_y^+=Q(y,x)partial_y^+partial_x^+ for xne y and partial^-_xpartial_y^+=δ(x-y)+Q(x,y)partial_y^+partial^-_x for (x,y)in X^2. In particular, for q = 1, the ACR become the canonical commutation relations and for q = -1, the ACR become the canonical anticommutation relations. We define the ACR algebra as the algebra generated by operator-valued integrals of partial_x^+, partial_x^-. We construct a class of gauge-invariant quasi-free states on the ACR algebra. Each state from this class is completely determined by a positive self-adjoint operator T on the real space L 2( X, dx), which commutes with any operator of multiplication by a bounded function ψ(x^1). In the case Rq 0), we discuss the corresponding particle density ρ(x):=partial_x^+partial_x^-. For Re qin(0,1], using a renormalization, we rigorously define a vacuum state on the commutative algebra generated by operator-valued integrals of ρ(x). This state is given by a negative binomial point process. A scaling limit of these states as κto∞ gives the gamma random measure, depending on parameter {R}q.

  17. Gauge-Invariant Quasi-Free States on the Algebra of the Anyon Commutation Relations

    Science.gov (United States)

    Lytvynov, Eugene

    2016-10-01

    Let {X={R}^2} and let {qin{C}} , {|q|=1} . For {x=(x^1,x^2)} and {y=(y^1,y^2)} from {X^2} , we define a function {Q(x,y)} to be equal to q if {x1 y1} , and to {R}q if {x^1=y^1} . Let {partial_x^+} , {partial_x^-} ({xin X} ) be operator-valued distributions such that {partial_x^+} is the adjoint of {partial_x^-} . We say that {partial_x^+} , {partial_x^-} satisfy the anyon commutation relations (ACR) if {partial^+_xpartial_y^+=Q(y,x)partial_y^+partial_x^+} for {x≠ y} and {partial^-_xpartial_y^+=δ(x-y)+Q(x,y)partial_y^+partial^-_x} for {(x,y)in X^2} . In particular, for q = 1, the ACR become the canonical commutation relations and for q = -1, the ACR become the canonical anticommutation relations. We define the ACR algebra as the algebra generated by operator-valued integrals of {partial_x^+} , {partial_x^-} . We construct a class of gauge-invariant quasi-free states on the ACR algebra. Each state from this class is completely determined by a positive self-adjoint operator T on the real space L 2(X, dx), which commutes with any operator of multiplication by a bounded function {ψ(x^1)} . In the case {R}q 0} ), we discuss the corresponding particle density {ρ(x):=partial_x^+partial_x^-} . For {Re qin(0,1]} , using a renormalization, we rigorously define a vacuum state on the commutative algebra generated by operator-valued integrals of {ρ(x)} . This state is given by a negative binomial point process. A scaling limit of these states as {κto∞} gives the gamma random measure, depending on parameter {R}q.

  18. Localization of s-Wave and Quantum Effective Potential of a Quasi-free Particle with Position-Dependent Mass

    Institute of Scientific and Technical Information of China (English)

    JU Guo-Xing; XIANG Yang; REN Zhong-Zhou

    2006-01-01

    The properties of the s-wave for a quasi-free particle with position-dependent mass (PDM) have been discussed in details. Differed from the system with constant mass in which the localization of the s-wave for the free quantum particle around the origin only occurs in two dimensions, the quasi-free particle with PDM can experience attractive forces in D dimensions except D=1 when its mass function satisfies some conditions. The effective mass of a particle varying with its position can induce effective interaction, which may be attractive in some cases. The analytical expressions of the eigenfunctions and the corresponding probability densities for the s-waves of the two- and three-dimensional systems with a special PDM are given, and the existences of localization around the origin for these systems are shown.

  19. Polarization Observables T and F in single π0- and η-Photoproduction off quasi-free Nucleons

    Directory of Open Access Journals (Sweden)

    Strub Thomas

    2014-01-01

    Single π0- and η-photoproduction off a transversally polarized d-butanol target has been measured with circularly polarized bremsstrahlung photons generated by the MAMI-C electron microtron. With the nearly 4π acceptance of the combined Crystal Ball/TAPS setup the double polarization observable F and the target asymmetry T can be extracted for the first time for polarized, quasi-free neutrons over a wide energy and angular range.

  20. Ejection of quasi-free electron pairs from the helium atom ground state by single photon absorption

    CERN Document Server

    Schöffler, M S; Waitz, M; Trinter, F; Jahnke, T; Lenz, U; Jones, M; Belkacem, A; Landers, A; Pindzola, M S; Cocke, C L; Colgan, J; Kheifets, A; Bray, I; Schmidt-Böcking, H; Dörner, R; Weber, Th

    2012-01-01

    We investigate single photon double ionization (PDI) of helium at photon energies of 440 and 800 eV. We observe doubly charged ions with close to zero momentum corresponding to electrons emitted back-to-back with equal energy. These slow ions are the unique fingerprint of an elusive quasi-free PDI mechanism predicted by Amusia et al. nearly four decades years ago [J. Phys. B 8, 1248, (1975)] . It results from the non-dipole part of the electromagnetic interaction. Our experimental data are in excellent agreement with calculations performed using the convergent close coupling and time dependent close coupling methods.

  1. First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons

    Directory of Open Access Journals (Sweden)

    M. Dieterle

    2017-07-01

    Full Text Available The double-polarization observable E and the helicity-dependent cross sections σ1/2 and σ3/2 have been measured for the first time for single π0 photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the π0 meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the π0N final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI effects. However, there is no significant effect on the asymmetry E since the σ1/2 and σ3/2 components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry E measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons.

  2. HADES results in elementary reactions

    Directory of Open Access Journals (Sweden)

    Ramstein B.

    2014-01-01

    Full Text Available Recent results obtained with the HADES experimental set-up at GSI are presented with a focus on dielectron production and strangeness in pp and quasi-free np reactions. Perspectives related to the very recent experiment using the pion beam at GSI are also discussed.

  3. HADES results in elementary reactions

    Science.gov (United States)

    Ramstein, B.; Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Deveaux, C.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gill, K.; Golubeva, M.; Guber, F.; Gumberidze, M.; Harabasz, S.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Kardan, K.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Krása, A.; Krebs, E.; Kuc, H.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petousis, V.; Pietraszko, J.; Przygoda, W.; Rehnisch, L.; Reshetin, A.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmidt-Sommerfeld, K.; Schuldes, H.; Sellheim, P.; Siebenson, J.; Silva, L.; Sobolev, Yu. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Wendisch, C.; Wirth, J.; Wüstenfeld, J.; Zanevsky, Y.; Zumbruch, P.

    2014-11-01

    Recent results obtained with the HADES experimental set-up at GSI are presented with a focus on dielectron production and strangeness in pp and quasi-free np reactions. Perspectives related to the very recent experiment using the pion beam at GSI are also discussed.

  4. Path integral molecular dynamics simulation of quasi-free rotational motion of CO doped in a large para-hydrogen cluster

    Science.gov (United States)

    Mizumoto, Yoshihiko; Ohtsuki, Yukiyoshi

    2011-01-01

    Path integral molecular dynamics simulation is used to study the rotational motion of a CO molecule doped in a large para-hydrogen (p-H2) cluster. The quasi-free rotational motion of CO in a p-H2 cluster with a reduced rotational constant is derived from the imaginary-time orientational correlation functions, and is in good agreement with recent experimental observations. We attribute the reduced rotational constant to the low-viscous fluid-like behavior of the host p-H2 cluster.

  5. Quasi-free Cross Section Measurements at CLAS: γ D → p π - ( p ) , γ D → K * ( 892 ) 0 Λ ( p ) , γ D → K + Σ * ( 1385 ) - ( p )

    Energy Technology Data Exchange (ETDEWEB)

    Mattione, Paul [Carnegie Mellon U., JLAB

    2014-09-01

    Preliminary measurements of the quasi-free differential cross sections of the gD -->pp-(p), gD --> K*(892)0L(p), and gD --> K+S*(1385)-(p) reactions are shown using data from the Jefferson Lab Hall B CLAS g13 experiment. No experimental cross section data have yet been published on gD --> K*(892)0L(p), and the only published cross section data on gD --> K+S*(1385)-(p) are at forward angles, where t-channel K+ and K*+ exchanges are predicted to dominate. These data can be used to contribute to the search for the "missing" N* resonances, some of which are predicted to have non-negligible couplings to the excited strangeness channels. These cross sections are shown to be sizable compared to the ground-state channels, indicating that it is important to include excited channels in coupled-channels analyses used to extract the N* resonances. In addition, the gD --> pp-(p) data provide a significant increase to the world statistics, and will be used to study rescattering effects within the deuteron.

  6. Evidence for a cubic-to-icosahedral transition of quasi-free Pd-H-clusters controlled by the hydrogen content . On the phase transitions in Pd-H-clusters

    Science.gov (United States)

    Pundt, A.; Dornheim, M.; Guerdane, M.; Teichler, H.; Ehrenberg, H.; Reetz, M. T.; Jisrawi, N. M.

    2002-06-01

    An in situ synchrotron radiation study of quasi-free five nanometer-sized palladium clusters during hydrogen absorption is combined with molecular dynamics simulations to investigate the structural development. In the diffraction patterns, strong intensity changes are found that provide evidence for a structural phase transformation that is significantly different from the α α' Pd H bulk phase transition. The structural transition is reversible and driven by the hydrogen concentration. The intensity changes are consistent with a cubic-to-icosahedral structural phase transition obtained in molecular dynamical simulations using embedded-atom-method potentials.

  7. Photo nuclear reactions by QMD

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Tomoyuki; Niita, Koji; Chiba, Satoshi; Maruyama, Toshiki; Iwamoto, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-05-01

    QMD (Quantum Molecular Dynamics) was applied to photo nuclear reaction. Advantages of QMD were explained. The cross section of (Cr, pX) at 375 MeV/c was simulated. The results showed three peaks, the peak in the lowest momentum indicated contribution of statistics decay and the middle one, the largest peak, was contribution of quasi-free process (QF) which consisted of two-step process. Then, the total cross section of {pi} photoproduction for three target nuclei (C, Al and Cu) was simulated by QMD. The obtained values were larger than the experimental values, so that the present QMD calculation showed small {pi} adsorption. (S.Y.)

  8. Quasi-free Pi0 and Pi- electroproduction on 4He in the Delta-resonance region (Pi en Delta in symbolen) - Zie als voorbeeld titelblad -

    NARCIS (Netherlands)

    Steenbakkers, M.F.M.

    2004-01-01

    The reactions 4He(e, e' p3He)pi- and 4He(e, e' p3He)pi0 were studied simultaneously, and for the first time, in a large kinematical domain including the Delta-resonance region. This was achieved by detecting the recoiling 3He and 3H nuclei instead of the emitted pions. The dependences of the cross

  9. (p,px) reaction on /sup 6/Li and /sup 7/Li nuclei at incident proton energy of 70 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Gorpinich, O.K.; Kadkin, E.P.; Kondrat' ev, S.N.; Lobach, Yu.M.; Pasechnik, M.V.; Saltykov, L.S.; Tokarevskij, V.V. (AN Ukrainskoj SSR, Kiev. Inst. Yadernykh Issledovanij)

    1983-01-01

    Measurements of two-dimensional coincidence spectra of charged particles from the /sup 6/Li(p, 2p)/sup 5/He, /sup 6/Li(p, p..cap alpha..)/sup 2/H, /sup 7/Li(p, pt)/sup 4/He, /sup 7/Li(p, p..cap alpha..)/sup 3/H reactions has been carried out using the equipment for simultaneous investigation of correlation of charged particles of different types. The /sup 6/Li(p, pd) reaction probability reaches the maximum value when the residual nucleus momentum is close to zero. This fact may confirm an existance of strong /sup 6/Li ..cap alpha..d-clusterization. The /sup 7/Li(p, pt) reaction occurs with the minimum probability in a quasi-free region that confirms /sup 7/Li ..cap alpha..t-structure. A direct comparison of particle two-dimensional spectra projections of (p, px) type reactions reveals that a probability of quasi-free scattering of proton on deuteron (triton) /sup 6/Li(/sup 7/Li) cluster is higher than quasi-free scattering on intranuclear protons. This fact is also confirmed by an assumption on ..cap alpha..d(..cap alpha..t)-cluster /sup 6/Li(/sup 7/Li) nucleus structure.

  10. Validity test of the Trojan Horse Method applied to the {sup 7}Li+p{yields} {alpha}+{alpha} reaction via the {sup 3}He break-up

    Energy Technology Data Exchange (ETDEWEB)

    Tumino, A.; Spitaleri, C.; Sergi, M.L.; Cherubini, S.; La Cognata, M.; Lamia, L.; Romano, S.; Tudisco, S. [Universita di Catania, Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); Kroha, V.; Burjan, V.; Novac, J.; Vincour, J. [Nuclear Physics Institute of ASCR, Rez, Prague (Czech Republic); Fueloep, Z.; Somorjai, E. [Institute of Nuclear Research of Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Pizzone, R.G. [INFN Laboratori Nazionali del Sud, Catania (Italy)

    2006-03-15

    The Trojan Horse Method (THM) was applied to the {sup 3}He+{sup 7}Li interaction in order to investigate the quasi-free {sup 7}Li(p,{alpha}){sup 4}He reaction. The three-body experiment was performed at 33 MeV corresponding to a {sup 7}Li-p relative energy ranging from 50 keV to 7 MeV. The extracted {sup 7}Li(p,{alpha}){sup 4}He quasi-free cross-section was compared with the behavior of direct data, as well as with the result of a previous THM investigation on the {sup 7}Li(p,{alpha}){sup 4}He reaction off the neutron in {sup 2}H. A good agreement between data sets shows up throughout the energy range investigated, providing a very important validity test of the pole approximation for the THM. (orig.)

  11. Trojan Horse as an indirect technique in nuclear astrophysics. Resonance reactions

    CERN Document Server

    Mukhamedzhanov, A M; Irgaziev, B F; Kadyrov, A S; La Cognata, M; Spitaleri, C; Tribble, R E

    2007-01-01

    The Trojan Horse method is a powerful indirect technique that provides information to determine astrophysical factors for binary rearrangement processes $x + A \\to b + B$ at astrophysically relevant energies by measuring the cross section for the Trojan Horse reaction $a + A \\to y+ b + B$ in quasi-free kinematics. We present the theory of the Trojan Horse method for resonant binary subreactions based on the half-off-energy-shell R matrix approach which takes into account the off-energy-shell effects and initial and final state interactions.

  12. Medium effects on spin observables of proton knockout reactions

    Energy Technology Data Exchange (ETDEWEB)

    Krein, G. [Instituto de Fisica Teorica (IFT), Sao Paulo, SP (Brazil); Maris, T.A.J.; Rodrigues, B.B.; Veit, E.A. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica

    1994-07-01

    Medium modifications of the properties of bound nucleons and mesons are investigated by means of medium energy quasi free proton knockout reactions with polarized incident protons. The sensitivity of the spin observables of these reactions to modifications of the nucleon and meson properties is studied using the Bonn one-boson exchange model of the nucleon-nucleon interaction. A method proposed to extract the pp analysing power in medium from the (p, 2 p) asymmetries indicates a reduction of this quantity compared to its free space value. This reduction is linked to modifications of masses and coupling constants of the nucleons and mesons in the nucleus. The implications of these modifications for another spin observable to be measured in the future are discussed. (author). 39 refs, 9 figs.

  13. Study of the {sup 17}O(n,α){sup 14}C reaction: Extension of the Trojan Horse Method to neutron induced reactions

    Energy Technology Data Exchange (ETDEWEB)

    Guardo, G. L.; Lamia, L.; Spitaleri, C.; Cherubini, S.; Rapisarda, G. G.; Sergi, M. L. [INFN - Laboratori Nazionali del Sud, Catania, Italy and Department of Physics and Astronomy, University of Catania, Catania (Italy); Gulino, M. [INFN - Laboratori Nazionali del Sud, Catania, Italy and University of Enna (Italy); Tang, X. D.; Bucher, B.; Couder, M.; Davies, P.; Boer, R. de; Fang, X.; Lamm, L.; Ma, C.; Notani, M.; OBrien, S.; Roberson, D.; Tan, W.; Wiescher, M. [Department of Physics and Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN (United States); and others

    2014-05-02

    The experimental study of the {sup 17}O(n,α){sup 14}C reaction has been performed in the energy range 0-350 keV. This reaction could play an important role in explaining heavy elements (s-process) nucleosynthesis in various astrophysical scenario. To overcome the practical problems arising from the neutrons production, a new application of the Trojan Horse Method has been recently suggested. In more details, the {sup 17}O(n,α){sup 14}C reaction has been studied using the quasi-free {sup 2}H({sup 17}O,α{sup 14}C){sup 1}H reaction, induced at an energy of 43.5 MeV. The measurement allows one to investigate the ℓ=3, 75 keV resonance (E*=8.125 MeV, J{sup π}=5{sup −}), absent in the available direct measurements because of centrifugal suppression effects.

  14. Direct nuclear reaction experiments for stellar nucleosynthesis

    Science.gov (United States)

    Cherubini, S.

    2017-09-01

    During the last two decades indirect methods where proposed and used in many experiments in order to measure nuclear cross sections between charged particles at stellar energies. These are among the lowest to be measured in nuclear physics. One of these methods, the Trojan Horse method, is based on the Quasi-Free reaction mechanism and has proved to be particularly flexible and reliable. It allowed for the measurement of the cross sections of various reactions of astrophysical interest using stable beams. The use and reliability of indirect methods become even more important when reactions induced by Radioactive Ion Beams are considered, given the much lower intensity generally available for these beams. The first Trojan Horse measurement of a process involving the use of a Radioactive Ion Beam dealt with the ^{18} F(p, α ^{15} O process in Nova conditions. To obtain pieces of information on this process, in particular about its cross section at Nova energies, the Trojan Horse method was applied to the ^{18} F(d, α ^{15} O)n three body reaction. In order to establish the reliability of the Trojan Horse method approach, the Treiman-Yang criterion is an important test and it will be addressed briefly in this paper.

  15. Investigation of the dd -> 3He n \\pi 0 reaction with WASA-at-COSY

    CERN Document Server

    :,; Augustyniak, W; Bardan, W; Bashkanov, M; Bergmann, F S; Berłowski, M; Bhatt, H; Büscher, M; Calén, H; Ciepał, I; Clement, H; Coderre, D; Czerwiński, E; Demmich, K; Doroshkevich, E; Engels, R; Erven, W; Eyrich, W; Fedorets, P; Föhl, K; Fransson, K; Goldenbaum, F; Goslawski, P; Goswami, A; Grigoryev, K; Gullström, C --O; Hanhart, C; Hauenstein, F; Heijkenskjöld, L; Hejny, V; Hinterberger, F; Hodana, M; Höistad, B; Jany, A; Jany, B R; Jarczyk, L; Johansson, T; Kamys, B; Kemmerling, G; Khan, F A; Khoukaz, A; Kirillov, D A; Kistryn, S; Klaja, J; Kleines, H; Kłos, B; Krapp, M; Krzemień, W; Kulessa, P; Kupść, A; Lalwani, K; Lersch, D; Li, L; Lorentz, B; Magiera, A; Maier, R; Marciniewski, P; Mariański, B; Mikirtychiants, M; Morsch, H --P; Moskal, P; Nandi, B K; Ohm, H; Ozerianska, I; del Rio, E Perez; Piskunov, N M; Pluciński, P; Podkopał, P; Prasuhn, D; Pricking, A; Pszczel, D; Pysz, K; Pyszniak, A; Redmer, C F; Ritman, J; Roy, A; Rudy, Z; Sawant, S; Schmidt, A; Schadmand, S; Sefzick, T; Serdyuk, V; Shah, N; Siemaszko, M; Siudak, R; Skorodko, T; Skurzok, M; Smyrski, J; Sopov, V; Stassen, R; Stepaniak, J; Stephan, E; Sterzenbach, G; Stockhorst, H; Ströher, H; Szczurek, A; Tolba, T; Trzciński, A; Varma, R; Wagner, G J; W\\keglorz, W; Wolke, M; Wrońska, A; Wüstner, P; Wurm, P; Yamamoto, A; Yuan, X; Zabierowski, J; Zheng, C; Zieliński, M J; Zipper, W; Złomańczuk, J; Żuprański, P; Żurek, M

    2013-01-01

    An exclusive measurement of the dd -> 3He n \\pi 0 reaction was carried at a beam momentum of p = 1.2 GeV/c using the WASA-at-COSY facility. For the first time data on the total cross section as well as differential distributions were obtained. The data are described with a phenomenological approach based on a combination of a quasi-free model and a partial wave expansion for three-body reaction. The total cross section is found to be \\sigma(tot) = (2.89 +- 0.01(stat) +- 0.06(sys) +- 0.29(norm)) \\mu b. The contribution of the quasi-free processes (with the neutron being target or beam spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of the phase space. The remaining part of the cross section can be described within a partial wave decomposition indicating the significance of p-wave contributions in the final state.

  16. Trojan Horse particle invariance in fusion reactions

    Science.gov (United States)

    Pizzone, R. G.; Spitaleril, C.; Bertulani, C.; Mukhamedzhanov, A.; Blokhintsev, L.; La Cognata, M.; Lamia, L.; Spartá, R.; Tumino, A.

    2015-01-01

    Trojan Horse method plays an important part for the measurement of several charged particle induced reactions cross sections of astrophysical interest. In order to better understand its cornerstones and the related applications to different astrophysical scenarios several tests were performed to verify all its properties and the possible future perspectives. The Trojan Horse nucleus invariance for the binary reactions d(d,p)t, 6,7Li(p,α)3,4He was therefore tested using the appropriate quasi free break- ups, respectively. In the first cases results from 6Li and 3He break up were used, while for the lithium fusion reactions break-ups of 2H and 3He were compared. The astrophysical S(E)-factors for the different processes were then extracted in the framework of the PlaneWave Approximation applied to the different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement between data coming from different break-up schemes confirms the applicability of the plane wave approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present cases. Moreover the astrophysical implications of the results will also be discussed in details.

  17. Trojan horse method with neutrons induced reactions: The 17O(n,α)14C reaction

    Science.gov (United States)

    Guardo, G. L.; Spitaleri, C.; Lamia, L.; Gulino, M.; Tang, X.; Bucher, B.; Burjan, V.; Couder, M.; Davies, P.; deBoer, R.; Fang, X.; Kroha, V.; La Cognata, M.; Ma, C.; Mrazek, J.; Mukhamedzhanov, A.; Notani, M.; O'Brien, S.; Pizzone, R. G.; Rapisarda, G. G.; Roberson, D.; Sergi, M. L.; Tan, W.; Wiescher, M.

    2017-06-01

    The experimental study of the 17O(n,α)14C reaction has been performed in the energy range 0-350 keV. This reaction could play an important role in explaining heavy elements (s-process) nucleosynthesis in various astrophysical scenario. To over-come the practical problems arising from the neutrons production, a new application of the Trojan Horse Method has been recently suggested. In more details, the 17O(n,α)14C reaction has been studied using the quasi-free 2H(17O,α14C)1H reaction, induced at an energy of 43.5 MeV. The measurement allows one to investigate the ℓ=3, 75 keV resonance (E*=8.125 MeV, Jπ=5-), absent in the available direct measurements because of centrifugal suppression effects. Moreover, the results show that the contribution of the 166 keV and 236 keV resonances is in energy agreement with the available direct data. A clear contribution of the -7 keV subthreshold level is also present.

  18. The Trojan Horse method for nuclear astrophysics: Recent results for direct reactions

    Science.gov (United States)

    Tumino, A.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.

    2014-05-01

    The Trojan Horse method is a powerful indirect technique to determine the astrophysical factor for binary rearrangement processes A+x→b+B at astrophysical energies by measuring the cross section for the Trojan Horse (TH) reaction A+a→B+b+s in quasi free kinematics. The Trojan Horse Method has been successfully applied to many reactions of astrophysical interest, both direct and resonant. In this paper, we will focus on direct sub-processes. The theory of the THM for direct binary reactions will be shortly presented based on a few-body approach that takes into account the off-energy-shell effects and initial and final state interactions. Examples of recent results will be presented to demonstrate how THM works experimentally.

  19. The Trojan Horse method for nuclear astrophysics: Recent results for direct reactions

    Energy Technology Data Exchange (ETDEWEB)

    Tumino, A.; Gulino, M. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Catania, Italy and Università degli Studi di Enna Kore, Enna (Italy); Spitaleri, C.; Cherubini, S.; Romano, S. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Catania, Italy and Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Cognata, M. La; Pizzone, R. G.; Rapisarda, G. G. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Catania (Italy); Lamia, L. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy)

    2014-05-09

    The Trojan Horse method is a powerful indirect technique to determine the astrophysical factor for binary rearrangement processes A+x→b+B at astrophysical energies by measuring the cross section for the Trojan Horse (TH) reaction A+a→B+b+s in quasi free kinematics. The Trojan Horse Method has been successfully applied to many reactions of astrophysical interest, both direct and resonant. In this paper, we will focus on direct sub-processes. The theory of the THM for direct binary reactions will be shortly presented based on a few-body approach that takes into account the off-energy-shell effects and initial and final state interactions. Examples of recent results will be presented to demonstrate how THM works experimentally.

  20. Analyzing power of the [sup 2]H(n vector,np)n breakup reaction at 67 MeV in selected kinematical configurations

    Energy Technology Data Exchange (ETDEWEB)

    Kistryn, S.; Hajdas, W.; Lang, J.; Mueller, R. (Inst. fuer Mittelenergiephysik, Eidgenoessische Technische Hochschule, Zurich (Switzerland)); Balewski, J.; Bodek, K.; Jarczyk, L.; Kamys, B.; Strzalkowski, A. (Inst. of Physics, Jagiellonian Univ., Krakow (Poland)); Dechant, B.; Krug, J.; Luebcke, W.; Ruehl, H.; Spangardt, G.; Steinke, M.; Stephan, M.; Kamke, D. (Inst. fuer Experimentalphysik 1, Univ. Bochum (Germany)); Henneck, R. (Inst. fuer Physik, Univ. Basel (Switzerland)); Witala, H.; Cornelius, T.; Gloeckle, W.; Golak, J. (Inst. fuer Theoretische Physik 2, Univ. Bochum (German))

    1992-10-05

    The angular distribution of the analyzing power A[sub y] for the [sup 2]H(n vector, np)n breakup reaction at 67 MeV was measured in two kinematical regions: np quasi-free scattering and np final-state interaction. The results are compared with rigorous three-nucleon calculations using the Paris potential and allowing for charge dependence in the [sup 1]S[sub 0] state. According to the actual experimental conditions energy averaging was simulated in the theoretical calculations. In both configurations agreement between experimental and calculated values is found. (orig.).

  1. Tyree-body mechanisms in the {sup 3}He(e,e'p) reactions at high missing momentum

    Energy Technology Data Exchange (ETDEWEB)

    J.-M. Laget

    2004-10-01

    A particular three-body mechanism is responsible for the missing strength which has been reported in {sup 3}He(e,e{prime}p) reactions at missing momentum above 700 MeV/c. It corresponds to the absorption of the virtual photon by a nucleon at rest which subsequently propagates on-shell and emits a meson which is reabsorbed by the pair formed by the two other nucleons. Its amplitude, which is negligible in photon induced reactions as well as in the electro-production of an on-shell meson, becomes maximal in the quasi-free kinematics (X=1). It relates the amplitude of the {sup 3}He(e,e{prime}p)D reaction to the amplitude of pD elastic scattering at backward angles.

  2. Study of the {sup 9}Be(p,{alpha}){sup 6}Li reaction via the Trojan Horse Method

    Energy Technology Data Exchange (ETDEWEB)

    Romano, S.; Lamia, L.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Tumino, A. [INFN, Laboratori Nazionali del Sud, Catania (Italy); Universita di Catania, Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Catania (Italy); Li, C.; Pizzone, R.G. [INFN, Laboratori Nazionali del Sud, Catania (Italy)

    2006-03-15

    The Trojan Horse Method has been applied to the {sup 2}H({sup 9}Be,{sup 6}Li{alpha})n three-body reaction in order to investigate the {sup 9}Be(p,{alpha}){sup 6}Li two-body reaction, which is involved in the study of light element abundances (lithium, beryllium and boron). A coincidence measurement was performed in order to identify the presence of the quasi-free mechanism in the three-body reaction, needed for the application of the method. The astrophysical S(E)-factor was extracted and compared to direct data. No information about electron screening effects can be extracted due to the poor resolution of the indirect data. (orig.)

  3. Measurement of cross section and astrophysical factor of the d(d,p)t reaction using the Trojan Horse Method

    Energy Technology Data Exchange (ETDEWEB)

    Rinollo, A. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy)]|[Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Romano, S. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy)]|[Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Spitaleri, C. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy)]|[Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Bonomo, C. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy)]|[Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Cherubini, S. [Ruhr-Universitaet Bochum (Germany); Del Zoppo, A.; Figuera, P. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy); La Cognata, M. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy)]|[Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Lamia, L.; Musumarra, A.; Pellegriti, M.G. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy)]|[Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy); Pizzone, R.G. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy); Rolfs, C.; Schuermann, D.; Strieder, F. [Ruhr-Universitaet Bochum (Germany); Tudisco, S.; Tumino, A. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania (Italy)]|[Dipartimento di Metodologie Chimiche e Fisiche per l' Ingegneria, Universita di Catania (Italy)

    2005-07-25

    Knowledge about reactions involving deuterium is required for a correct understanding of stellar and primordial nucleosynthesis processes, and also in planning fusion reactors for energy production. We have studied the d(d,p)t reaction in the energy range from 1.5 MeV down to astrophysical energies by means of the Trojan Horse Method applied to the three-body {sup 6}Li(d,pt){alpha} reaction, at a beam energy of 14 MeV. Protons and tritons have been detected in coincidence and identified. Quasi-free events have been kinematically selected, in order to extract the cross section and the astrophysical factor, and compare them with the values measured for the direct d(d,p)t process.

  4. Low-energy neutron-deuteron reactions with N{sup 3}LO chiral forces

    Energy Technology Data Exchange (ETDEWEB)

    Golak, J.; Skibinski, R.; Topolnicki, K.; Witala, H. [Jagiellonian University, M. Smoluchowski Institute of Physics, Krakow (Poland); Epelbaum, E.; Krebs, H. [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany); Kamada, H. [Kyushu Institute of Technology, Department of Physics, Faculty of Engineering, Kitakyushu (Japan); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); JARA - High Performance Computing Forschungszentrum Juelich, Institute for Advanced Simulation, Institut fuer Kernphysik, Juelich Center for Hadron Physics, Juelich (Germany); Bernard, V. [CNRS/Univ. Paris-Sud, Institut de Physique Nucleaire, Orsay (France); Maris, P.; Vary, J. [Iowa State University, Department of Physics and Astronomy, Ames, Iowa (United States); Binder, S.; Calci, A.; Langhammer, J.; Roth, R. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Hebeler, K. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Extreme Matter Institute EMMI, Darmstadt (Germany); Nogga, A. [Juelich Center for Hadron Physics, Forschungszentrum Juelich, Institut fuer Kernphysik, Institute for Advanced Simulation, Juelich (Germany); Liebig, S.; Minossi, D. [Juelich Center for Hadron Physics, Forschungszentrum Juelich, Institut fuer Kernphysik, Juelich (Germany)

    2014-11-15

    We solve three-nucleon Faddeev equations with nucleon-nucleon and three-nucleon forces derived consistently in the framework of chiral perturbation theory at next-to-next-to-next-to-leading order in the chiral expansion. In this first investigation we include only matrix elements of the three-nucleon force for partial waves with the total two-nucleon (three-nucleon) angular momenta up to 3 (5/2). Low-energy neutron-deuteron elastic scattering and deuteron breakup reaction are studied. Emphasis is put on A{sub y} puzzle in elastic scattering and cross sections in symmetric-space-star and neutron-neutron quasi-free-scattering breakup configurations, for which large discrepancies between data and theory have been reported. (orig.)

  5. Low-energy neutron-deuteron reactions with N3LO chiral forces

    CERN Document Server

    Golak, J; Topolnicki, K; Witala, H; Epelbaum, E; Krebs, H; Kamada, H; Meissner, Ulf-G; Bernard, V; Maris, P; Vary, J; Binder, S; Calci, A; Hebeler, K; Langhammer, J; Roth, R; Nogga, A; Liebig, S; Minossi, D

    2014-01-01

    We solve three-nucleon Faddeev equations with nucleon-nucleon and three-nucleon forces derived consistently in the framework of chiral perturbation theory at next-to-next-to-next-to-leading order in the chiral expansion. In this first investigation we include only matrix elements of the three-nucleon force for partial waves with the total two-nucleon (three-nucleon) angular momenta up to 3 (5/2). Low-energy neutron-deuteron elastic scattering and deuteron breakup reaction are studied. Emphasis is put on Ay puzzle in elastic scattering and cross sections in symmetric-space-star and neutron-neutron quasi-free-scattering breakup configurations, for which large discrepancies between data and theory have been reported.

  6. Updated evidences of the Trojan Horse particle invariance for $^2$H(d,p)$^3$H reaction

    CERN Document Server

    Pizzone, R G; Bertulani, C A; Mukhamedzhanov, A M; Blokhintsev, L; La Cognata, M; Lamia, L; Rinollo, A; Spartá, R; Tumino, A

    2012-01-01

    The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was tested using the quasi free $^2$H($^6$Li, pt)$^4$He and $^2$H($^3$He,pt)H reactions after $^6$Li and $^3$He break-up, respectively. The astrophysical S(E)-factor for the d(d,p)t binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the Plane Wave Approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case.

  7. New measurement of $\\rm S_{bare}(E)$ factor of the d(d,p)t reaction at astrophysical energies via the Trojan-horse method

    CERN Document Server

    Li, Chengbo; Fu, Yuanyong; Zhou, Jing; Zhou, Shuhua; Meng, Qiuying; Spitaleri, C; Tumino, A; Pizzone, R G; Lamia, L

    2015-01-01

    The study of d(d,p)t reaction is very important for the nucleosynthesis in both standard Big Bang and stellar evolution, as well as for the future fusion reactor planning of energy production. The d(d,p)t bare nucleus astrophysical S(E) factor has been measured indirectly at energies from about 400 keV down to several keV by means of the Trojan horse method applied to the quasi-free process $\\rm {}^2H({}^6Li,pt){}^4He$ induced at the lithium beam energy of 9.5 MeV, which is closer to the zero quasi-free energy point, in CIAE HI-13 tandem accelerator laboratory. An accurate analysis leads to the determination of the d(d,p)t $\\rm S(E)$ factor $\\rm S_{bare}(0)=56.7 \\pm 2.0 keV*b$ and of the corresponding electron screening potential $\\rm U_e = 13.2 \\pm 4.3 eV$. In addition, this work also gives an updated test for the Trojan horse nucleus invariance comparing with previous indirect investigations using $\\rm {}^3He=(d+p)$ breakup.

  8. First measurements of spin correlations in the n{sup →}p{sup →}→dπ{sup 0} reaction

    Energy Technology Data Exchange (ETDEWEB)

    Shmakova, V. [Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Mchedlishvili, D. [Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); High Energy Physics Institute, Tbilisi State University, GE-0186 Tbilisi, Georgia (United States); Dymov, S., E-mail: s.dymov@fz-juelich.de [Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Azaryan, T. [Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Barsov, S. [St. Petersburg Nuclear Physics Institute, RU-188350 Gatchina (Russian Federation); Chiladze, D. [Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); High Energy Physics Institute, Tbilisi State University, GE-0186 Tbilisi, Georgia (United States); Engels, R. [Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); and others

    2013-11-04

    The transverse spin correlations A{sub x,x} and A{sub y,y} in the n{sup →}p{sup →}→dπ{sup 0} reaction have been measured for the first time in quasi-free kinematics at the COSY-ANKE facility using a polarised deuteron beam incident on a polarised hydrogen cell target. The results obtained for neutron energies close to 353 MeV and 600 MeV are in good agreement with the partial wave analysis of data on the isospin-related pp→dπ{sup +} reaction, though the present results cover kinematic regions that are largely absent from existing data sets.

  9. Reaction Graph

    Institute of Scientific and Technical Information of China (English)

    傅育熙

    1998-01-01

    The paper proposes reaction graphs as graphical representations of computational objects.A reaction graph is a directed graph with all its arrows and some of its nodes labeled.Computations are modled by graph rewriting of a simple nature.The basic rewriting rules embody the essence of both the communications among processes and cut-eliminations in proofs.Calculi of graphs are ideentified to give a formal and algebraic account of reaction graphs in the spirit of process algebra.With the help of the calculi,it is demonstrated that reaction graphs capture many interesting aspects of computations.

  10. Trojan Horse particle invariance for 2H(d,p3H reaction: a detailed study

    Directory of Open Access Journals (Sweden)

    Pizzone R.G.

    2014-03-01

    Full Text Available In the last decades the Trojan Horse method has played a crucial role for the measurement of several charged particle induced reactions cross sections of astrophysical interest. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The Trojan Horse nucleus invariance for the binary d(d,pt reaction was therefore tested using the quasi free 2H(6Li, pt4He and 2H(3He,ptH reactions after 6Li and 3He break-up, respectively. The astrophysical S(E-factor for the d(d,pt binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the plane wave approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case.

  11. The 12C(12C,α)20Ne and 12C(12C,p)23Na reactions at the Gamow peak via the Trojan Horse Method

    Science.gov (United States)

    Tumino, A.; Spitaleri, C.; Cherubini, S.; Guardo, L.; Gulino, M.; Indelicato, I.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Spartá, R.

    2016-05-01

    A measurement of the 12C(14N,α20Ne)2H and 12C(14N,p23Na)2Hreactions has been performed at a 14N beam energy of 30.0 MeV. The experiment aims to explore the extent to which contributing 24Mg excited states can be populated in the quasi-free reaction off the deuteron in 14N. In particular, the 24Mg excitation region explored in the measurement plays a key role in stellar carbon burning whose cross section is commonly determined by extrapolating high-energy fusion data. From preliminary results, α and proton channels are clearly identified. In particular, ground and first excited states of 20Ne and 23Na play a major role.

  12. AGB nucleosynthesis: The 19F(α, p)22Ne reaction at astrophysical energies

    Science.gov (United States)

    D'Agata, G.; Pizzone, R. G.; Spitaleri, C.; Blagus, S.; Figuera, P.; Grassi, L.; Guardo, G. L.; Gulino, M.; Hayakawa, S.; Indelicato, I.; Kshetri, R.; La Cognata, M.; Lamia, L.; Lattuada, M.; Mijatović, T.; Milin, M.; Miljanic, D.; Prepolec, L.; Sergi, M. L.; Skukan, N.; Soic, N.; Tokic, V.; Tumino, A.; Uroic, M.

    2017-06-01

    Learning how 19F is produced and destructed in AGB-stars is crucial. Fluorine abundance is in fact important, given that it is strongly tied to standard and extra-mixing processes taking place in AGB-stars. This kind of objects are considered to be the main sources of fluorine in galactic environment, in which experimental abundances are far overestimated. For this reason the reaction 19F(α, p)22Ne, that represents the main destruction channel in He-rich environment, was studied at energies corresponding to T˜2.108 K. Such reaction has been studied with direct method at Ebeam = 1100 keV for alpha particles impinging on a fluorine target, corresponding to EC.M. ˜ 900 keV, still far from the Gamow window, placed at 390÷800 keV, below the Coulomb barrier (3.81 MeV). An experiment was performed at Rujer Boskovic Institut (Zagreb), applying the Trojan Horse Method. With this experimental procedure we were able to select the quasi-free contribution coming from 6Li(19F,p 22Ne)2H at Ebeam = 6 MeV at kinematically useful angles. We measured the 19F(α, p)22Ne at 0 MeV ≤ EC.M ≤ 0.9 MeV, extracting the two body cross-section in absolute units at energies of astrophysical interest.

  13. Low-energy d+d fusion reactions via the Trojan Horse Method

    Energy Technology Data Exchange (ETDEWEB)

    Tumino, A., E-mail: tumino@lns.infn.it [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Universita degli Studi di Enna ' Kore' , Enna (Italy); Spitaleri, C. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mukhamedzhanov, A.M. [Cyclotron Institute Texas A and M University, College Station, TX (United States); Typel, S. [Excellence Cluster Universe, Technische Universitaet Muenchen, Garching (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH - Theorie, Darmstadt (Germany); Aliotta, M. [School of Physics and Astronomy, University of Edinburgh, Edinburgh, Scotland (United Kingdom); Scottish Universities Physics Alliance (United Kingdom); Burjan, V. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Gimenez del Santo, M. [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Kiss, G.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); ATOMKI, Debrecen (Hungary); Kroha, V.; Hons, Z. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); La Cognata, M.; Lamia, L. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mrazek, J. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Pizzone, R.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Piskor, S. [Nuclear Physics Institute of ASCR, Rez (Czech Republic); Rapisarda, G.G.; Romano, S.; Sergi, M.L.; Sparta, R. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy)

    2011-06-06

    The bare nucleus S(E) factors for the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions have been measured for the first time via the Trojan Horse Method off the proton in {sup 3}He from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre-Main-Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

  14. Study of spectator tagging in the reaction np{yields}pp{pi} with a deuteron beam

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Bary, M.; Gillitzer, A.; Kilian, K.; Morsch, H.P.; Paul, N.; Ritman, J.; Roderburg, E.; Ucar, A.; Wintz, P.; Wuestner, P. [Forschungszentrum Juelich, Institut fuer Kernphysik, Juelich (Germany); Brinkmann, K.-Th.; Dshemuchadse, S.; Freiesleben, H.; Jaekel, R.; Karsch, L.; Kuhlmann, E.; Schoenmeier, P.; Schulte-Wissermann, M.; Sun, G.Y. [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); Clement, H.; Doroshkevich, E.; Erhardt, A.; Wagner, G.J. [Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany); Eyrich, W.; Pizzolotto, C.; Schroeder, W.; Teufel, A.; Wagner, M. [Universitaet Erlangen, Physikalisches Institut, Erlangen (Germany); Moeller, K.; Naumann, L. [Forschungszentrum Rossendorf, Institut fuer Kern- und Hadronenphysik, Dresden (Germany); Zupranski, P. [Andrzej Soltan Institute for Nuclear Studies, Warsaw (Poland)

    2006-09-15

    The reaction dp{yields}ppp{pi}{sup -} has been studied in a kinematically complete experiment at a single beam momentum p{sub d}=1.85 GeV/c (T=759 MeV). All four ejectiles have been detected in the large-acceptance time-of-flight spectrometer COSY-TOF. We analyzed the data along the lines of the spectator model as a means to isolate the quasi-free np{yields}pp{pi}{sup -} reaction. The spectator proton was identified by its momentum and flight direction thus yielding access to the associated Fermi motion of the bound neutron. A comparison is carried out with Monte Carlo simulations based on two different parameterizations of the deuteron wave function. Up to a Fermi momentum of roughly 150 MeV/c no significant deviations between experimental and simulated data of various observables were found from which we conclude that the deuteron can indeed be taken as a valid substitute for the neutron. (orig.)

  15. Study of spectator tagging in the reaction np → ppπwith a deuteron beam

    Science.gov (United States)

    Abdel-Bary, M.; Brinkmann, K.-Th.; Clement, H.; Doroshkevich, E.; Dshemuchadse, S.; Erhardt, A.; Eyrich, W.; Freiesleben, H.; Gillitzer, A.; Jäkel, R.; Karsch, L.; Kilian, K.; Kuhlmann, E.; Möller, K.; Morsch, H. P.; Naumann, L.; Paul, N.; Pizzolotto, C.; Ritman, J.; Roderburg, E.; Schönmeier, P.; Schroeder, W.; Schulte-Wissermann, M.; Sun, G. Y.; Teufel, A.; Ucar, A.; Wagner, G. J.; Wagner, M.; Wintz, P.; Wüstner, P.; Zupranski, P.

    2006-09-01

    The reaction dp ensuremath rightarrow ppp π^- has been studied in a kinematically complete experiment at a single beam momentum ensuremath pd=1.85GeV/c (T = 759MeV). All four ejectiles have been detected in the large-acceptance time-of-flight spectrometer COSY-TOF. We analyzed the data along the lines of the spectator model as a means to isolate the quasi-free ensuremath nprightarrow ppπ^- reaction. The spectator proton was identified by its momentum and flight direction thus yielding access to the associated Fermi motion of the bound neutron. A comparison is carried out with Monte Carlo simulations based on two different parameterizations of the deuteron wave function. Up to a Fermi momentum of roughly 150MeV/c no significant deviations between experimental and simulated data of various observables were found from which we conclude that the deuteron can indeed be taken as a valid substitute for the neutron.

  16. Capture reactions

    NARCIS (Netherlands)

    Endt, P.M.

    1956-01-01

    Capture reactions will be considered here from the viewpoint of the nuclear spectroscopist. Especially important to him are the capture of neutrons, protons, and alpha particles, which may proceed through narrow resonances, offering a well defined initial state for the subsequent deexcitation proces

  17. Allergic Reactions

    Science.gov (United States)

    ... round, they may be caused by exposure to indoor allergens such as dust mites, indoor molds or pets. Urticaria, or hives, is characterized ... home. Video: What is an allergic reaction? » Utility navigation Donate Annual meeting Browse your conditions Check pollen ...

  18. First Measurement of the 19F(α, p)22Ne Reaction at Energies of Astrophysical Relevance

    Science.gov (United States)

    Pizzone, R. G.; D’Agata, G.; La Cognata, M.; Indelicato, I.; Spitaleri, C.; Blagus, S.; Cherubini, S.; Figuera, P.; Grassi, L.; Guardo, G. L.; Gulino, M.; Hayakawa, S.; Kshetri, R.; Lamia, L.; Lattuada, M.; Mijatović, T.; Milin, M.; Miljanić D., Đ.; Prepolec, L.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Skukan, N.; Soić, N.; Tokić, V.; Tumino, A.; Uroić, M.

    2017-02-01

    The observational 19F abundance in stellar environments systematically exceeds the predicted one, thus representing one of the unsolved challenges for stellar modeling. It is therefore clear that further investigation is needed in this field. In this work, we focus our attention on the measurement of the {}19{{F}}{(α ,p)}22{Ne} reaction in the astrophysical energy range, between 0.2 and 0.8 MeV (far below the Coulomb barrier, 3.8 MeV), as it represents the main destruction channel in He-rich environments. The lowest energy at which this reaction has been studied with direct measurements is ∼0.66 MeV, covering only the upper tail of the Gamow window, causing the reaction-rate evaluation to be based on extrapolation. To investigate lower energies, the {}19{{F}}{(α ,p)}22{Ne} reaction has been studied by means of the Trojan horse method, applied to the quasi-free {}6{Li}{{(}19{{F}},{p}22{Ne})}2{{H}} reaction at E beam = 6 MeV. The indirect cross section of the {}19{{F}}{(α ,p)}22{Ne} reaction at energies ≲1 MeV was extracted, fully covering the astrophysical region of interest and overlapping existing direct data for normalization. Several resonances have been detected for the first time inside the Gamow window. The reaction rate has been calculated, showing an increase up to a factor of 4 with respect to the literature at astrophysical temperatures. This might lead to potential major astrophysical implications.

  19. Spallation reactions; Reactions de spallation

    Energy Technology Data Exchange (ETDEWEB)

    Cugon, J.

    1996-12-31

    Spallation reactions dominate the interactions of hadrons with nuclei in the GeV range (from {approx} 0.1 to {approx} 10 GeV). They correspond to a sometimes important ejection of light particles leaving most of the time a residue of mass commensurate with the target mass. The main features of the experimental data are briefly reviewed. The most successful theoretical model, namely the intranuclear cascade + evaporation model, is presented. Its physical content, results and possible improvements are critically discussed. Alternative approaches are shortly reviewed. (author). 84 refs.

  20. Helicity dependence of the γ {sup 3}He → πX reactions in the Δ(1232) resonance region

    Energy Technology Data Exchange (ETDEWEB)

    Costanza, S.; Rigamonti, F. [INFN, Sezione di Pavia, Pavia (Italy); Universita di Pavia, Dipartimento di Fisica, Pavia (Italy); Mushkarenkov, A.; Braghieri, A.; Pedroni, P. [INFN, Sezione di Pavia, Pavia (Italy); Romaniuk, M.; Mandaglio, G. [INFN, Sezione di Catania, Catania (Italy); Universita di Messina, Dipartimento di Fisica e Scienze della Terra, Messina (Italy); Aguar Bartolome, P.; Ahrens, J.; Arends, H.J.; Heid, E.; Jahn, O.; Kashevarov, V.L.; Ostrick, M.; Ortega, H.; Otte, P.B.; Oussena, B.; Schumann, S.; Thomas, A.; Unverzagt, M. [Universitaet Mainz, Institut fuer Kernphysik, Mainz (Germany); Annand, J.R.M.; Hamilton, D.; Howdle, D.; Livingston, K.; MacGregor, I.J.D.; Mancell, J.; McGeorge, J.C.; Rosner, G. [University of Glasgow, SUPA School of Physics and Astronomy, Glasgow (United Kingdom); Beck, R. [University of Bonn, Helmholtz-Institut fuer Strahlen und Kernphysik, Bonn (Germany); Bekrenev, V.; Kruglov, S.; Kulbardis, A. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Berghaeuser, H.; Drexler, P.; Metag, V.; Thiel, M. [University of Giessen, II Physikalisches Institut, Giessen (Germany); Briscoe, W.J.; Downie, E.J. [The George Washington University, Washington, DC (United States); Cherepnya, S.N.; Fil' kov, L.V.; Lisin, V.; Polonski, A. [Institute for Nuclear Research, Moscow (Russian Federation); Collicott, C. [Dalhousie University, Halifax, NS (Canada); Saint Mary' s University, Halifax, NS (Canada); Fix, A. [Tomsk Polytechnic University, Tomsk (Russian Federation); Glazier, D.I. [University of Glasgow, SUPA School of Physics and Astronomy, Glasgow (United Kingdom); University of Edinburgh, SUPA School of Physics and Astronomy, Edinburgh (United Kingdom); Heil, W.; Krimmer, J. [Universitaet Mainz, Institut fuer Physik, Mainz (Germany); Hornidge, D.; Middleton, D.G. [Mount Allison University, Sackville, NB (Canada); Jaegle, I.; Keshelashvili, I.; Krusche, B.; Oberle, M.; Pheron, F.; Rostomyan, T.; Werthmueller, D. [University of Basel, Institut fuer Physik, Basel (Switzerland); Huber, G.M. [University of Regina, Regina, SK (Canada); Jude, T.; Watts, D.P. [University of Edinburgh, SUPA School of Physics and Astronomy, Edinburgh (United Kingdom); Kondratiev, R. [Lebedev Physical Institute, Moscow (Russian Federation); Korolija, M.; Supek, I. [Rudjer Boskovic Institute, Zagreb (Croatia); Manley, D.M. [Kent State University, Kent, Ohio (United States); Nefkens, B.M.K.; Starostin, A. [University of California, Los Angeles, California (United States); Nikolaev, A. [Universita di Pavia, Dipartimento di Fisica, Pavia (Italy); Prakhov, S. [Universitaet Mainz, Institut fuer Kernphysik, Mainz (Germany); The George Washington University, Washington, DC (United States); University of California, Los Angeles, California (United States); Sarty, A.J. [Saint Mary' s University, Halifax, NS (Canada); Collaboration: A2 Collaboration

    2014-11-15

    The helicity dependences of the differential cross sections for the semi-inclusive γ {sup 3}He → π{sup 0} X and γ {sup 3}He → π{sup ±} X reactions have been measured for the first time in the energy region 200 < E{sub γ} 450 MeV. The experiment was performed at the tagged photon beam facility of the MAMI accelerator in Mainz using a longitudinally polarised high-pressure {sup 3}He gas target. Hadronic products were measured with the large-acceptance Crystal Ball detector complemented with additional devices for charged-particle tracking and identification. Unpolarised differential cross sections and their helicity dependence are compared with theoretical calculations using the Fix-Arenhoevel model. The effect of the intermediate excitation of the Δ(1232) resonance can be clearly seen from this comparison, especially for the polarised case, where nuclear effects are relatively small. The model provides a better theoretical description of the unpolarised charged pion photoproduction data than the neutral pion channel. It does significantly better in describing the helicity-dependent data in both channels. These comparisons provide new information on the mechanisms involved in pion photoproduction on {sup 3}He and suggest that a polarised {sup 3}He target can provide valuable information on the corresponding polarised quasi-free neutron reactions. (orig.)

  1. Measurement of the pn → ppπ0π− Reaction in Search of the ABC Resonance

    Directory of Open Access Journals (Sweden)

    Pricking A.

    2012-12-01

    Full Text Available With pd collisions at Tp = 1.2 GeV exclusive measurements of the quasi-free pn → ppπ0π− reaction have been carried out. Using the WASA detector setup at COSY total and differential cross sections have been obtained for the energy region √s = 2.35 − 2.48 GeV. Though this includes the region of the ABC effect and its associated resonance structure, no low-mass enhancement (ABC effect is found in the π0π−-invariant mass spectrum – in agreement with the constraint from Bose statistics demanding the isovector pion pair to be in relative p-wave. Conventional calculations including t-channel processes for Roper, Δ(1600 and ΔΔ excitations and their decays, which are well-known from the study of the two-pion production in pp collisions, provide a reasonable description of the data at high energies, but fall low at low energies. From this we conclude that a large contribution from a so far unknown isoscalar low-energy process is missed in the calculations. Inclusion of the ABC resonance at m = 2.37 GeV with Γ = 70 MeV and I(JP = 0(3+, which was recently observed in the pn → dπ0π0 reaction, leads to a much improved description of the data at low energies.

  2. Measurement of the pn → ppπ0π- Reaction in Search of the ABC Resonance

    Science.gov (United States)

    Skorodko, T.; Bashkanov, M.; Clement, H.; Doroshkevich, E.; Perez del Rio, E.; Pricking, A.; Wagner, G. J.

    2012-12-01

    With pd collisions at Tp = 1.2 GeV exclusive measurements of the quasi-free pn → ppπ0π- reaction have been carried out. Using the WASA detector setup at COSY total and differential cross sections have been obtained for the energy region √s = 2.35 - 2.48 GeV. Though this includes the region of the ABC effect and its associated resonance structure, no low-mass enhancement (ABC effect) is found in the π0π--invariant mass spectrum - in agreement with the constraint from Bose statistics demanding the isovector pion pair to be in relative p-wave. Conventional calculations including t-channel processes for Roper, Δ(1600) and ΔΔ excitations and their decays, which are well-known from the study of the two-pion production in pp collisions, provide a reasonable description of the data at high energies, but fall low at low energies. From this we conclude that a large contribution from a so far unknown isoscalar low-energy process is missed in the calculations. Inclusion of the ABC resonance at m = 2.37 GeV with Γ = 70 MeV and I(JP) = 0(3+), which was recently observed in the pn → dπ0π0 reaction, leads to a much improved description of the data at low energies.

  3. AN UPDATED {sup 6}Li(p, {alpha}){sup 3}He REACTION RATE AT ASTROPHYSICAL ENERGIES WITH THE TROJAN HORSE METHOD

    Energy Technology Data Exchange (ETDEWEB)

    Lamia, L.; Spitaleri, C.; Sergi, M. L. [Dipartimento di Fisica e Astronomia, Universita di Catania, I-95123 Catania (Italy); Pizzone, R. G.; Tumino, A.; La Cognata, M. [INFN-Laboratori Nazionali del Sud, I-95125 Catania (Italy); Tognelli, E.; Degl' Innocenti, S.; Prada Moroni, P. G. [Dipartimento di Fisica, Universita di Pisa, I-56127 Pisa (Italy); Pappalardo, L. [Dipartimento di Fisica e Scienze della Terra, Universita di Ferrara, I-44100 Ferrara (Italy)

    2013-05-01

    The lithium problem influencing primordial and stellar nucleosynthesis is one of the most interesting unsolved issues in astrophysics. {sup 6}Li is the most fragile of lithium's stable isotopes and is largely destroyed in most stars during the pre-main-sequence (PMS) phase. For these stars, the convective envelope easily reaches, at least at its bottom, the relatively low {sup 6}Li ignition temperature. Thus, gaining an understanding of {sup 6}Li depletion also gives hints about the extent of convective regions. For this reason, charged-particle-induced reactions in lithium have been the subject of several studies. Low-energy extrapolations of these studies provide information about both the zero-energy astrophysical S(E) factor and the electron screening potential, U{sub e} . Thanks to recent direct measurements, new estimates of the {sup 6}Li(p, {alpha}){sup 3}He bare-nucleus S(E) factor and the corresponding U{sub e} value have been obtained by applying the Trojan Horse method to the {sup 2}H({sup 6}Li, {alpha} {sup 3}He)n reaction in quasi-free kinematics. The calculated reaction rate covers the temperature window 0.01 to 2T{sub 9} and its impact on the surface lithium depletion in PMS models with different masses and metallicities has been evaluated in detail by adopting an updated version of the FRANEC evolutionary code.

  4. On the investigation of resonances above and below the threshold in nuclear reactions of astrophysical interest using the Trojan Horse Method.

    Science.gov (United States)

    La Cognata, M.; Spitaleri, C.; Cherubini, S.; Gulino, M.; Indelicato, I.; Lamia, L.; Pizzone, R. G.; Romano, S.; Trippella, O.; Tumino, A.

    2017-07-01

    The occurrence of resonances in reactions of astrophysical interest might significantly enhance the astrophysical factor with respect to the direct reaction contribution, divert nucleosynthesis path and change the energy production, with significant impact on astrophysics. Moreover, the determination of resonance parameters, that is, energy, spin-parity and partial widths, allows one to perform nuclear structure studies leading, for instance, to determine the cluster structure of the state under investigation. However, nuclear reactions in stars take place at energies well below ~ 1 MeV owing to the typical temperatures characterising these environments. Therefore, the Coulomb barrier exponentially suppressing the cross section and the electron screening effect, due to the shielding of nuclear charges by atomic electrons, make it very difficult to provide accurate astrophysical factors. The THM is an indirect method allowing to overcome such difficulties. It makes use of quasi-free reactions with three particles in the exit channel, a + A → c + C + s, to deduce the cross section of the reaction of astrophysical interest, a + x → c + C, under the hypothesis that A shows a strong x + s cluster structure, right at astrophysical energies. By using a generalised R-matrix approach, the resonance parameters can be deduced from THM data allowing one to perform a full spectroscopic study of low-energy and sub-threshold resonances. In this work, we will discuss two examples of reactions of astrophysical interest, whose cross sections show a resonant behaviour: the19F(p, α)16O cross section that displays resonances at energies above the particle emission threshold and the13C(α, n)16O reaction, dominated by the -3 keV sub-threshold resonance due to the 6.356 MeV level in17O.

  5. Measurement of the np→npπ0π0 reaction in search for the recently observed d⁎(2380 resonance

    Directory of Open Access Journals (Sweden)

    P. Adlarson

    2015-04-01

    Full Text Available Exclusive measurements of the quasi-free np→npπ0π0 reaction have been performed by means of dp collisions at Td=2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region s=(2.35–2.46 GeV, which includes the region of the ABC effect and its associated d⁎(2380 resonance. Adding the d⁎ resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of Fäldt and Wilkin as well with those of Albadajedo and Oset. The ABC effect, i.e. the low-mass enhancement in the π0π0-invariant mass spectrum, is found to be very modest – if present at all, which might pose a problem to some of its interpretations.

  6. Search for eta-mesic 4He in the dd->3He n pi0 and dd->3He p pi- reactions with the WASA-at-COSY facility

    CERN Document Server

    Adlarson, P; Bardan, W; Bashkanov, M; Bergmann, F S; Berlowski, M; Bhatt, H; Bondar, A; Buescher, 9 M; Calen, H; Ciepal, I; Clement, H; Czerwinski, E; Demmich, K; Engels, R; Erven, A; Erven, W; Eyrich, W; Fedorets, P; Foehl, K; Fransson, K; Goldenbaum, F; Goswami, A; Grigoryev, K; Gullstroem, C -O; Heijkenskjoeld, L; Hejny, V; Huesken, N; Jarczyk, L; Johansson, T; Kamys, B; Kelkar, N G; Kemmerling, G; Khatri, G; Khoukaz, A; Khreptak, O; Kirillov, D A; Kistryn, S; Kleines, H; Klos, B; Krzemien, W; Kulessa, P; Kupsc, A; Kuzmin, A; Lalwani, K; Lersch, D; Lorentz, B; Magiera, A; Maier, R; Marciniewski, P; Marianski, B; Morsch, H -P; Moskal, P; Ohm, H; del Rio, E Perez; Piskunov, N M; Prasuhn, D; Pszczel, D; Pysz, K; Pyszniak, A; Ritman, J; Roy, A; Rudy, Z; Rundel, O; Sawant, S; Schadmand, S; Schaetti-Ozerianska, I; Sefzick, T; Serdyuk, V; Shwartz, B; Sitterberg, K; Skorodko, T; Skurzok, M; Smyrski, J; Sopov, V; Stassen, R; Stepaniak, J; Stephan, E; Sterzenbach, G; Stockhorst, H; Stroeher, H; Szczurek, A; Trzcinski, A; Varma, R; Wolke, M; Wronska, A; Wuestner, P; Yamamoto, A; Zabierowski, J; Zielinski, M J; Zlomanczuk, J; Zupranski, P; Zurek, M

    2016-01-01

    The search for 4He-eta bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd->3He n pi0 and dd->3He p pi- processes. The beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the dd->4He eta reaction ranging from Q=-70 MeV to Q=30 MeV. The luminosity was determined based on the dd->3He n reaction and quasi-free proton-proton scattering via dd->pp n_spectator n_spectator reactions. The excitation functions determined independently for the measured reactions do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in dd->(4He-eta)_bound->3He n pi0 and dd->(4He-eta)_bound->3He p pi- processes were determined taking into account the isospin relation between both the channels considered. The results of the analysis depend on the assumptions of the N* momentum distribution in t...

  7. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  8. Production of the "K-pp"-like structure in the d(π+,K+) reaction at 1.69 GeV/c

    Science.gov (United States)

    Nagae, Tomofumi

    2016-10-01

    We have investigated the π+ + d →K+ + X reaction at 1.69 GeV/c at the hadron experimental hall of J-PARC. Systems with baryon number B = 2 and strangeness S = - 1 are produced in this reaction. Owing to the very wide momentum acceptance of the spectrometer, we were able to search from the ΛN threshold to above the K bar NN threshold, which covers the energy region where the K- pp bound state and/or the Σ (1385) N bound state could show up. We observed a significant shift of the quasi-free Σ (1385) / Λ (1405) production peak by approximately 30 MeV to the lighter mass side. Further, with the coincidence of two protons in the final state, a broad bump structure was observed with a mass and width of 2275-18+17(stat.)-30+21 (syst.) MeV /c2 and 162-45+87(stat.)-78+66 (syst.) MeV coming from the K- pp →Σ0 + p decay.

  9. [Allergic reactions to transfusion].

    Science.gov (United States)

    Hergon, E; Paitre, M L; Coeffic, B; Piard, N; Bidet, J M

    1987-04-01

    Frequent allergic reactions following transfusion are observed. Usually, they are benign but sometimes we observe severe allergic reactions. Adverse reactions may be brought about by least two mechanisms. First, immediate-type hypersensibility reactions due to IgE. Secondly, anaphylactic-type reactions due to interaction between transfused IgA and class specific anti IgA in the recipient's plasma. They are characterized by their severest form (anaphylactic shock). The frequency of severe reactions following the transfusion blood plasma is very low. These transfusion reactions are complement-mediated and kinins-mediated. Prevention of allergic reactions is necessary among blood donors and recipients.

  10. New Determination of the 2H(d,p)3H and 2H(d,n)3He Reaction Rates at Astrophysical Energies

    Science.gov (United States)

    Tumino, A.; Spartà, R.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Pizzone, R. G.; Tognelli, E.; Degl'Innocenti, S.; Burjan, V.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Mrazek, J.; Piskor, S.; Prada Moroni, P. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

    2014-04-01

    The cross sections of the 2H(d,p)3H and 2H(d,n)3He reactions have been measured via the Trojan Horse method applied to the quasi-free 2H(3He,p 3H)1H and 2H(3He,n 3He)1H processes at 18 MeV off the proton in 3He. For the first time, the bare nucleus S(E) factors have been determined from 1.5 MeV, across the relevant region for standard Big Bang nucleosynthesis, down to the thermal energies of deuterium burning in the pre-main-sequence (PMS) phase of stellar evolution, as well as of future fusion reactors. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from the available direct data and existing fitting curves, with substantial variations in the electron screening by more than 50%. As a consequence, the reaction rates for astrophysics experience relevant changes, with a maximum increase of up to 20% at the temperatures of the PMS phase. From a recent primordial abundance sensitivity study, it turns out that the 2H(d,n)3He reaction is quite influential on 7Li, and the present change in the reaction rate leads to a decrease in its abundance by up to 10%. The present reaction rates have also been included in an updated version of the FRANEC evolutionary code to analyze their influence on the central deuterium abundance in PMS stars with different masses. The largest variation of about 10%-15% pertains to young stars (=1 M ⊙.

  11. Double Pion Production Reactions

    CERN Document Server

    Oset, E; Cano, F; Hernández, E; Kamalov, S S; Nacher, J C; Tejedor, J A G

    1999-01-01

    We report on reactions producing two pions induced by real and virtual photons or nucleons. The role of different resonances in these reactions is emphasized. Novel results on coherent two pion photoproduction in nuclei are also reported.

  12. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  13. Microscale Thermite Reactions.

    Science.gov (United States)

    Arnaiz, Francisco J.; Aguado, Rafael; Arnaiz, Susana

    1998-01-01

    Describes the adaptation of thermite (aluminum with metal oxides) reactions from whole-class demonstrations to student-run micro-reactions. Lists detailed directions and possible variations of the experiment. (WRM)

  14. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  15. Measurement of the 10 keV resonance in the $^{10}$B($p, \\alpha_0$)$^7$Be reaction via the Trojan Horse Method

    CERN Document Server

    Spitaleri, C; Puglia, S M R; Romano, S; La Cognata, M; Crucilla, V; Pizzone, R G; Rapisarda, G G; Sergi, M L; Del Santo, M Gimenez; Carlin, N; Munhoz, M G; Souza, F A; de Toledo, A Szanto; Tumino, A; Irgaziev, B; Mukhamedzhanov, A; Tabacaru, G; Burjan, V; Kroha, V; Hons, Z; Mrazek, J; Zhou, Shu-Hua; Li, Chengbo; Wen, Qungang; Wakabayashi, Y; Yamaguchi, H

    2014-01-01

    The $^{10}$B(p,$\\alpha_0$)$^7$Be bare nucleus astrophysical S(E)-factor has been measured for the first time at energies from about 100 keV down to about 5 keV by means of the Trojan Horse Method (THM). In this energy region, the S(E)-factor is strongly dominated by the 8.699 MeV $^{11}$C level (J$^{\\pi}$=$\\frac{5}{2}$$^+$), producing an s-wave resonance centered at about 10 keV in the entrance channel. Up to now, only the high energy tail of this resonant has been measured, while the low-energy trend is extrapolated from the available direct data. The THM has been applied to the quasi-free $^2$H($^{10}$B,$\\alpha_0$$^7$Be)n reaction induced at a boron-beam energy of 24.5 MeV. An accurate analysis brings to the determination of the $^{10}$B(p,$\\alpha_0$)$^7$Be S(E)-factor and of the corresponding electron screening potential $U_e$, thus giving for the first time an independent evaluation of it.

  16. Measurement of the Target-Normal Single-Spin Asymmetry in Deep-Inelastic Scattering from the Reaction 3He{uparrow}(e,e')X

    Energy Technology Data Exchange (ETDEWEB)

    Katich, Joseph; Qian, Xin; Zhao, Yuxiang; Allada, Kalyan; Aniol, Konrad; Annand, John; Averett, Todd; Benmokhtar, Fatiha; Bertozzi, William; Bradshaw, Elliott; Bosted, Peter; Camsonne, Alexandre; Canan, Mustafa; Cates, Gordon; Chen, Chunhua; Chen, Jian-Ping; Chen, Wei; Chirapatpimol, Khem; Chudakov, Eugene; Cisbani, Evaristo; Cornejo, Juan; Cusanno, Francesco; Dalton, Mark; Deconinck, Wouter; De Jager, Cornelis; De Leo, Raffaele; Deng, Xiaoyan; Deur, Alexandre; Ding, Huaibo; Dolph, Peter; Dutta, Chiranjib; Dutta, Dipangkar; El Fassi, Lamiaa; Frullani, Salvatore; Gao, Haiyan; Garibaldi, Franco; Gaskell, David; Gilad, Gilad; Gilman, Ronald; Glamazdin, Oleksandr; Golge, Serkan; Guo, Lei; Hamilton, David; Hansen, Jens-Ole; Higinbotham, Douglas; Holmstrom, Timothy; Huang, Jijun; Huang, Min; Ibrahim Abdalla, Hassan; Iodice, Mauro; Jin, Ge; Jones, Mark; Kelleher, Aidan; Kim, Wooyoung; Kolarkar, Ameya; Korsch, Wolfgang; LeRose, John; Li, Xiaomei; Li, Y; Lindgren, Richard; Liyanage, Nilanga; Long, Elena; Lu, Hai-jiang; Margaziotis, Demetrius; Markowitz, Pete; Marrone, Stefano; McNulty, Dustin; Meziani, Zein-Eddine; Michaels, Robert; Moffit, Bryan; Munoz Camacho, Carlos; Nanda, Sirish; Narayan, Amrendra; Nelyubin, Vladimir; Norum, Blaine; Oh, Yoomin; Osipenko, Mikhail; Parno, Diana; Peng, Jen-chieh; Phillips, Sarah; Posik, Matthew; Puckett, Andrew; Qiang, Yi; Rakhman, Abdurahim; Ransome, Ronald; Riordan, Seamus; Saha, Arunava; Sawatzky, Bradley; Schulte, Elaine; Shahinyan, Albert; Hashemi Shabestari, Mitra; Sirca, Simon; Stepanyan, Stepan; Subedi, Ramesh; Sulkosky, Vincent; Tang, Liguang; Tobias, William; Urciuoli, Guido; Vilardi, Ignazio; Wang, Kebin; Wang, Y; Wojtsekhowski, Bogdan; Yan, X; Yao, Huan; Ye, Yunxiu; Ye, Z; Yuan, Lulin; Zhan, Xiaohui; Zhang, Yi; Zhang, Y -W; Zhao, Bo; Zheng, Xiaochao; Zhu, Lingyan; Zhu, Xiaofeng; Zong, Xing

    2014-07-01

    We report the first measurement of the target single-spin asymmetry in deep-inelastic scattering from the inclusive reaction 3He{uparrow}(e,e')X on a 3He gas target polarized normal to the lepton plane. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.72 GeV, which is non-zero at the 2.75sigma level. Theoretical calculations, which assume two-photon exchange with quasi-free quarks, predict a neutron asymmetry of O(10−4) when both photons couple to one quark, and O(10−2) for the photons coupling to different quarks. Our measured asymmetry agrees both in sign and magnitude with the prediction that uses input based on the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.

  17. Measurement of the np → npπ0π0 reaction in search for the recently observed d*(2380) resonance

    Science.gov (United States)

    Adlarson, P.; Augustyniak, W.; Bardan, W.; Bashkanov, M.; Bergmann, F. S.; Berłowski, M.; Bhatt, H.; Bondar, A.; Büscher, M.; Calén, H.; Ciepał, I.; Clement, H.; Coderre, D.; Czerwiński, E.; Demmich, K.; Doroshkevich, E.; Engels, R.; Erven, A.; Erven, W.; Eyrich, W.; Fedorets, P.; Föhl, K.; Fransson, K.; Goldenbaum, F.; Goslawski, P.; Goswami, A.; Grigoryev, K.; Gullström, C.-O.; Hauenstein, F.; Heijkenskjöld, L.; Hejny, V.; Höistad, B.; Hüsken, N.; Jarczyk, L.; Johansson, T.; Kamys, B.; Kemmerling, G.; Khan, F. A.; Khoukaz, A.; Kirillov, D. A.; Kistryn, S.; Kleines, H.; Kłos, B.; Krzemień, W.; Kulessa, P.; Kupść, A.; Kuzmin, A.; Lalwani, K.; Lersch, D.; Lorentz, B.; Magiera, A.; Maier, R.; Marciniewski, P.; Mariański, B.; Mikirtychiants, M.; Morsch, H.-P.; Moskal, P.; Ohm, H.; Ozerianska, I.; Perez del Rio, E.; Piskunov, N. M.; Podkopał, P.; Prasuhn, D.; Pricking, A.; Pszczel, D.; Pysz, K.; Pyszniak, A.; Ritman, J.; Roy, A.; Rudy, Z.; Sawant, S.; Schadmand, S.; Sefzick, T.; Serdyuk, V.; Shwartz, B.; Siudak, R.; Skorodko, T.; Skurzok, M.; Smyrski, J.; Sopov, V.; Stassen, R.; Stepaniak, J.; Stephan, E.; Sterzenbach, G.; Stockhorst, H.; Ströher, H.; Szczurek, A.; Täschner, A.; Trzciński, A.; Varma, R.; Wagner, G. J.; Wolke, M.; Wrońska, A.; Wüstner, P.; Wurm, P.; Yamamoto, A.; Zabierowski, J.; Zieliński, M. J.; Zink, A.; Złomańczuk, J.; Żuprański, P.; Żurek, M.

    2015-04-01

    Exclusive measurements of the quasi-free np → npπ0π0 reaction have been performed by means of dp collisions at Td = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region √{ s} = (2.35- 2.46) GeV, which includes the region of the ABC effect and its associated d* (2380) resonance. Adding the d* resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of Fäldt and Wilkin as well with those of Albadajedo and Oset. The ABC effect, i.e. the low-mass enhancement in the π0π0-invariant mass spectrum, is found to be very modest - if present at all, which might pose a problem to some of its interpretations.

  18. Measurement of the Target-Normal Single-Spin Asymmetry in Deep-Inelastic Scattering from the Reaction $^{3}\\mathrm{He}^{\\uparrow}(e,e')X$

    CERN Document Server

    Katich, J; Zhao, Y X; Allada, K; Aniol, K; Annand, J R M; Averett, T; Benmokhtar, F; Bertozzi, W; Bradshaw, P C; Bosted, P; Camsonne, A; Canan, M; Cates, G D; Chen, C; Chen, J -P; Chen, W; Chirapatpimol, K; Chudakov, E; Cisbani, E; Cornejo, J C; Cusanno, F; Dalton, M M; Deconinck, W; de Jager, C W; De Leo, R; Deng, X; Deur, A; Ding, H; Dolph, P A M; Dutta, C; Dutta, D; Fassi, L El; Frullani, S; Gao, H; Garibaldi, F; Gaskell, D; Gilad, S; Gilman, R; Glamazdin, O; Golge, S; Guo, L; Hamilton, D; Hansen, O; Higinbotham, D W; Holmstrom, T; Huang, J; Huang, M; Ibrahim, H F; Iodice, M; Jiang, X; Jin, G; Jones, M K; Kelleher, A; Kim, W; Kolarkar, A; Korsch, W; LeRose, J J; Li, X; Li, Y; Lindgren, R; Liyanage, N; Long, E; Lu, H -J; Margaziotis, D J; Markowitz, P; Marrone, S; McNulty, D; Meziani, Z -E; Michaels, R; Moffit, B; Camacho, C Muńoz; Nanda, S; Narayan, A; Nelyubin, V; Norum, B; Oh, Y; Osipenko, M; Parno, D; Peng, J C; Phillips, S K; Posik, M; Puckett, A J R; Qiang, Y; Rakhman, A; Ransome, R D; Riordan, S; Saha, A; Sawatzky, B; Schulte, E; Shahinyan, A; Shabestari, M H; Širca, S; Stepanyan, S; Subedi, R; Sulkosky, V; Tang, L -G; Tobias, A; Urciuoli, G M; Vilardi, I; Wang, K; Wang, Y; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yuan, L; Zhan, X; Zhang, Y; Zhang, Y -W; Zhao, B; Zheng, X; Zhu, L; Zhu, X; Zong, X

    2013-01-01

    We report the first measurement of the target single-spin asymmetry in deep-inelastic scattering from the inclusive reaction $^3$He$^{\\uparrow}\\left(e,e' \\right)X$ on a $^3$He gas target polarized normal to the lepton plane. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of $1.7 2$ GeV, which is non-zero at the $2.75\\sigma$ level. Theoretical calculations, which assume two-photon exchange with quasi-free quarks, predict a neutron asymmetry of $O(10^{-4})$ when both photons couple to one quark, and $O(10^{-2})$ for the photons coupling to different quarks. Our measured asymmetry agrees both in sign and magnitude with the prediction that uses input based on the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.

  19. Measurement of the $np \\to np\\pi^0\\pi^0$ Reaction in Search for the Recently Observed $d^*(2380)$ Resonance

    CERN Document Server

    Adlarson, P; Bardan, W; Bashkanov, M; Bergmann, F S; Berłowski, M; Bhatt, H; Bondar, A; Büscher, M; Calén, H; Ciepał, I; Clement, H; Coderre, D; Czerwiński, E; Demmich, K; Doroshkevich, E; Engels, R; Erven, A; Erven, W; Eyrich, W; Fedorets, P; Föhl, K; Fransson, K; Goldenbaum, F; Goslawski, P; Goswami, A; Grigoryev, K; Gullström, C --O; Hauenstein, F; Heijkenskjöld, L; Hejny, V; Höistad, B; Hüsken, N; Jarczyk, L; Johansson, T; Kamys, B; Kemmerling, G; Khan, F A; Khoukaz, A; Kirillov, D A; Kistryn, S; Kleines, H; Kłos, B; Krzemień, W; Kulessa, P; Kupść, A; Kuzmin, A; Lalwani, K; Lersch, D; Lorentz, B; Magiera, A; Maier, R; Marciniewski, P; Mariański, B; Mikirtychiants, M; Morsch, H --P; Moskal, P; Ohm, H; Ozerianska, I; del Rio, E Perez; Piskunov, N M; Podkopał, P; Prasuhn, D; Pricking, A; Pszczel, D; Pysz, K; Pyszniak, A; Ritman, J; Roy, A; Rudy, Z; Sawant, S; Schadmand, S; Sefzick, T; Serdyuk, V; Shwartz, B; Siudak, R; Skorodko, T; Skurzok, M; Smyrski, J; Sopov, V; Stassen, R; Stepaniak, J; Stephan, E; Sterzenbach, G; Stockhorst, H; Ströher, H; Szczurek, A; Täschner, A; Trzciński, A; Varma, R; Wagner, G J; Wolke, M; Wrońska, A; Wüstner, P; Wurm, P; Yamamoto, A; Zabierowski, J; Zieliński, M J; Zink, A; Złomańczuk, J; Żuprański, P; Żurek, M

    2014-01-01

    Exclusive measurements of the quasi-free $np \\to np\\pi^0\\pi^0$ reaction have been performed by means of $dp$ collisions at $T_d$ = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated $d^*(2380)$ resonance. Adding the $d^*$ resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of F\\"aldt and Wilkin as well Albadajedo and Oset. The ABC effect, {\\it i.e.} the low-mass enhancement in the $\\pi^0\\pi^0$-invariant mass spectrum, is found to be very modest - if present at all, which might pose a problem to some of its interpretations.

  20. Reaction systems with precipitation

    Directory of Open Access Journals (Sweden)

    Marek Rogalski

    2015-04-01

    Full Text Available This article proposes expanding Reaction Systems of Ehrenfeucht and Rozenberg by incorporating precipitation reactions into it. This improves the computing power of Reaction Systems by allowing us to implement a stack. This addition enables us to implement a Deterministic Pushdown Automaton.

  1. Beam-energy dependence and updated test of the Trojan-horse nucleus invariance via a measurement of the 2H(d ,p )3H reaction at low energies

    Science.gov (United States)

    Li, Chengbo; Wen, Qungang; Tumino, A.; Fu, Yuanyong; Zhou, Jing; Zhou, Shuhua; Meng, Qiuying; Spitaleri, C.; Pizzone, R. G.; Lamia, L.

    2017-03-01

    The 2H(d ,p )3H bare nucleus astrophysical S (E ) factor has been measured indirectly at energies from about 500 keV down to several keV by means of the Trojan-horse method applied to the 2H(6Li,p t )4He quasifree reaction induced at 11 MeV. The obtained results are compared with direct data as well as with previous indirect investigation of the same binary reactions. It shows that the precision of S (E ) data in the low-energy range extracted via the same Trojan-horse nuclei [6Li=(d ⊕α )] becomes better when the incident energy of the virtual binary process decreases from high value down to the lower Gamow energy range, which near the zero-quasi-free-energy point. The very good agreement between data extracted from different Trojan-horse nuclei [6Li=(d ⊕α ) vs 3He=(d ⊕p )] gives a strong updated test for the independence of the binary indirect cross section on the chosen Trojan-horse nucleus at low energies.

  2. Study of the excited {Delta} resonance ways of decay in {sup 4}He and other nuclei with the ({sup 3}He,T) reaction at 2 GeV; Etude des voies de decroissance de la resonance {Delta} excitee dans l`{sup 4}He et d`autres noyaux par la reaction ({sup 3}He,T) a 2 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Tarle-Rousteau, S.

    1995-05-10

    This thesis describes the ({sup 3}He,t) experiment carried out at 2 GeV at the Saturne National Laboratory (CEA Saclay, France) on {sup 1}H, {sup 2}H, {sup 4}He, {sup 12}C and {sup 208}Pb targets. The charged particles (pions and/or protons) from the {Delta} resonance deexcitation are detected in coincidence with triton using the Diogene large angle detector. New informations are obtained on the ways of {Delta} resonance decay in nuclei. Three modes of decay are investigated: the quasi-free decay, the {Delta}N into NN absorption and the coherent pions production. Modifications of {Delta} resonance properties in nuclei with respect to those of free {Delta} are analysed using the experimental results about pions diffusion, photons absorption, charge exchange reaction and {Delta}-hole model conclusions. The quasi-deuteron absorption process on {sup 4}He is studied using a Monte-Carlo simulation. Coherent pions production is also analysed in detail on {sup 4}He and {sup 12}C target nuclei. The process is very sensitive to {Delta}-hole correlations involved in the longitudinal spin canal which shifts the nucleus response in the {Delta} resonance region towards the low transferred energies. (J.S.). 85 refs., 72 figs., 10 tabs., 1 annexe.

  3. Noncanonical Reactions of Flavoenzymes

    Directory of Open Access Journals (Sweden)

    Pablo Sobrado

    2012-11-01

    Full Text Available Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetonephosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base reactions or as a nucleophile or electrophile. In addition, the flavin cofactor is proposed to function as a “molecular scaffold” in the formation of UDP-galactofuranose and alkyl-dihydroxyacetonephosphate by forming a covalent adduct with reaction intermediates.

  4. Gamow-Teller strength in the ( p , n ) reaction at 136 MeV on sup 20 Ne, sup 24 Mg, and sup 28 Si

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, B.D.; Tamimi, N.; Baldwin, A.R.; Elaasar, M.; Madey, R.; Manley, D.M.; Mostajabodda' vati, M.; Watson, J.W.; Zhang, W.M. (Department of Physics, Kent State University, Kent, Ohio 44242 (USA)); Foster, C.C. (Indiana University Cyclotron Facility, Bloomington, Indiana 47408 (USA))

    1991-01-01

    Gamow-Teller (GT) strength distributions were studied in the ({ital p},{ital n}) reaction at 136 MeV on the self-conjugate {ital s}-{ital d} shell nuclei {sup 20}Ne, {sup 24}Mg, and {sup 28}Si. The measurements were performed in two separate experiments with the beam-swinger neutron time-of-flight facility at the Indiana University Cyclotron Facility. The flight paths were 91 and 131 m, respectively, for the two experiments. The neutrons were detected in large-volume plastic-scintillation detectors. The overall time resolutions were about 825 ps; this provided energy resolutions from 300 to 400 keV. GT strength was identified as {Delta}{ital l}=0 contributions in transitions to discrete final states and also in the background and continuum. The 0{degree}, {Delta}l=0 cross sections were converted to {ital B}(GT) units using a universal'' conversion formula calibrated to ({ital p},{ital n}) reactions on other even-even {ital s}-{ital d} shell nuclei. The resulting {ital B}(GT) distributions were compared with full {ital s}-{ital d} shell-model predictions. The distribution for {sup 24}Mg is described well, but the distributions for {sup 20}Ne and {sup 28}Si are described poorly. The total {ital B}(GT) strength observed in discrete states (up to 12 MeV of excitation) for each reaction is 65{plus minus}10 % of that predicted. If one considers {ital B}(GT) strength observed in the continuum above a calculated quasi-free-scattering background, the strength increases to 70--100 % of that predicted. If one considers {ital B}(GT) strength in an analysis of the full continuum (up to {similar to}20 MeV), the entire amount predicted may be observed. These results are consistent with that observed in other light nuclei.

  5. Reaction kinetics of polybutylene terephthalate polycondensation reaction

    NARCIS (Netherlands)

    Darda, P. J.; Hogendoorn, J. A.; Versteeg, G. F.; Souren, F.

    2005-01-01

    The kinetics of the forward polycondensation reaction of polybutylene terephthalate (PBT) has been investigated using thermogravimetric analysis (TGA). PBT - prepolymer with an initial degree of polymerization of 5.5 was used as starting material. The PBT prepolymer was prepared from dimethyl tereph

  6. Transfusion reaction - hemolytic

    Science.gov (United States)

    ... of allergic transfusion reactions that do not cause hemolysis. ... transfusion, the transfusion must be stopped right away. Blood samples from the recipient (person getting the transfusion) and ...

  7. Desosamine in multicomponent reactions

    NARCIS (Netherlands)

    Achatz, Sepp; Dömling, Alexander

    2006-01-01

    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  8. Metal-mullite reactions

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)

    1993-11-01

    Mullite was reacted with pure Al and with Ti or Zr dissolved in Ag-Cu eutectic alloys at 1100 C in Ar. Analysis of the Ti and Zr-containing specimens showed reaction zones with compositions of Ti{sub 50}Cu{sub 3O}O{sub 20} and ZrO{sub 2}, respectively. The Al-mullite specimen showed much more extensive penetration into the ceramic and a more diffuse reaction zone than the other two systems. Al{sub 2}O{sub 3} and Si were the main reaction products for Al-mullite reaction.

  9. Reactions at Solid Surfaces

    CERN Document Server

    Ertl, Gerhard

    2009-01-01

    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  10. Desosamine in multicomponent reactions

    NARCIS (Netherlands)

    Achatz, Sepp; Dömling, Alexander

    2006-01-01

    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  11. Fluorogenic organocatalytic reactions

    NARCIS (Netherlands)

    Raeisolsadati Oskouei, M.

    2017-01-01

    In this thesis, we introduce fluorescence spectroscopy as a new tool to gain insight into the interactions between the substrates and catalyst during organocatalytic reactions. The ultimate goal is to resolve the kinetics of the binding and reaction steps and obtain detailed understanding of the

  12. Chemical burn or reaction

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000059.htm Chemical burn or reaction To use the sharing features on this page, please enable JavaScript. Chemicals that touch skin can lead to a reaction on the skin, throughout the body, or both. ...

  13. Reactions to Attitudinal Deviancy.

    Science.gov (United States)

    Levine, John M.; Allen, Vernon L.

    This paper presents a critical review of empirical and theoretical treatments of group reaction to attitudinal deviancy. Inspired by Festinger's (1950) ideas on resolution of attitudinal discrepancies in groups, Schachter (1951) conducted an experiment that has greatly influenced subsequent research and theory concerning reaction to attitudinal…

  14. Allergic reactions to vaccines.

    Science.gov (United States)

    Wood, Robert A

    2013-09-01

    Anaphylactic reactions to vaccines are rare but do occur, and have been reported for nearly every vaccine. And while the reaction rate per each dose of vaccine is low, this is a common clinical question due in large part to the enormous numbers of vaccines administered. Reactions are most often due to vaccine constituents rather than the microbial components of the vaccine, but in many instances, the specific ingredient triggering the reaction cannot be definitively identified. Evaluation of patients with suspected vaccine reactions should begin by determining whether the symptoms and timing of the reaction were consistent with a true allergic reaction, followed by an assessment to determine whether the patient needs further doses of the vaccine in question, or similar vaccines, in the future. Skin and serologic testing to vaccines and vaccine constituents can then be performed to further assess the potential cause of the reaction and to develop a plan for future immunizations. Specific guidelines for the administration of influenza vaccines to egg allergic patients have been revised to allow virtually all patients to receive this vaccine in a straightforward manner. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Chemical reaction and separation method

    NARCIS (Netherlands)

    Jansen, J.C.; Kapteijn, F.; Strous, S.A.

    2005-01-01

    The invention is directed to process for performing a chemical reaction in a reaction mixture, which reaction produces water as by-product, wherein the reaction mixture is in contact with a hydroxy sodalite membrane, through which water produced during the reaction is removed from the reaction mixtu

  16. The Reaction Wheel Pendulum

    CERN Document Server

    Block, Daniel J; Spong, Mark W

    2007-01-01

    This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t

  17. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

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

  18. Firefighter Nozzle Reaction

    DEFF Research Database (Denmark)

    Chin, Selena K.; Sunderland, Peter B.; Jomaas, Grunde

    2017-01-01

    Nozzle reaction and hose tension are analyzed using conservation of fluid momentum and assuming steady, inviscid flow and a flexible hose in frictionless contact with the ground. An expression that is independent of the bend angle is derived for the hose tension. If this tension is exceeded owing...... to anchor forces, the hose becomes straight. The nozzle reaction is found to equal the jet momentum flow rate, and it does not change when an elbow connects the hose to the nozzle. A forward force must be exerted by a firefighter or another anchor that matches the forward force that the jet would exert...... on a perpendicular wall. Three reaction expressions are derived, allowing it to be determined in terms of hose diameter, jet diameter, flow rate, and static pressure upstream of the nozzle. The nozzle reaction predictions used by the fire service are 56% to 90% of those obtained here for typical firefighting hand...

  19. Oral Hypersensitivity Reactions

    Science.gov (United States)

    ... food, food additives, drugs, oral hygiene products, and dental materials. Q: Are there any specific foods that are ... dental treatment trigger a hypersensitivity reaction? A: Some dental materials used by the dentist can cause a hypersensitivity ...

  20. Response reactions: equilibrium coupling.

    Science.gov (United States)

    Hoffmann, Eufrozina A; Nagypal, Istvan

    2006-06-01

    It is pointed out and illustrated in the present paper that if a homogeneous multiple equilibrium system containing k components and q species is composed of the reactants actually taken and their reactions contain only k + 1 species, then we have a unique representation with (q - k) stoichiometrically independent reactions (SIRs). We define these as coupling reactions. All the other possible combinations with k + 1 species are the coupled reactions that are in equilibrium when the (q - k) SIRs are in equilibrium. The response of the equilibrium state for perturbation is determined by the coupling and coupled equilibria. Depending on the circumstances and the actual thermodynamic data, the effect of coupled equilibria may overtake the effect of the coupling ones, leading to phenomena that are in apparent contradiction with Le Chatelier's principle.

  1. Autocatalysis in reaction networks.

    Science.gov (United States)

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2014-10-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view toward the persistence conjecture. We introduce the notions of "drainable" and "self-replicable" (or autocatalytic) siphons. We show that: Every minimal critical siphon is either drainable or self-replicable; reaction networks without drainable siphons are persistent; and nonautocatalytic weakly reversible networks are persistent. Our results clarify that the difficulties in proving the persistence conjecture are essentially due to competition between drainable and self-replicable siphons.

  2. Translated chemical reaction networks.

    Science.gov (United States)

    Johnston, Matthew D

    2014-05-01

    Many biochemical and industrial applications involve complicated networks of simultaneously occurring chemical reactions. Under the assumption of mass action kinetics, the dynamics of these chemical reaction networks are governed by systems of polynomial ordinary differential equations. The steady states of these mass action systems have been analyzed via a variety of techniques, including stoichiometric network analysis, deficiency theory, and algebraic techniques (e.g., Gröbner bases). In this paper, we present a novel method for characterizing the steady states of mass action systems. Our method explicitly links a network's capacity to permit a particular class of steady states, called toric steady states, to topological properties of a generalized network called a translated chemical reaction network. These networks share their reaction vectors with their source network but are permitted to have different complex stoichiometries and different network topologies. We apply the results to examples drawn from the biochemical literature.

  3. Ofloxacin induced hypersensitivity reaction

    Directory of Open Access Journals (Sweden)

    Hari Babu Ramineni

    2015-01-01

    Full Text Available Ofloxacin is a commonly used antimicrobial agent to combat various infections. The adverse profile of quinolones includes gastrointestinal symptoms, which are the most frequent, neuropsychiatric symptoms, hematologic abnormalities are less common. We report a rare case of ofloxacin induced hypersensitivity reaction in a 57 year old female patient with complaints of rashes over the axilla, upper limb and back, abdomen, thorax associated with exfoliation of skin all over the axilla associated with severe itching. Based on history and clinical examination patient was diagnosed as ofloxacin induced hypersensitivity reaction and was successfully treated with antihistamines and corticosteroids. Pharmacovigilance should be a part of patient care in order to reduce occurrence of adverse drug reaction and also encourage practitioners in reporting so as to gather more and more data regarding adverse drug reactions. [Int J Res Med Sci 2015; 3(1.000: 349-351

  4. Chemisorption And Precipitation Reactions

    Science.gov (United States)

    The transport and bioavailability of chemical components within soils is, in part, controlled by partitioning between solids and solution. General terms used to describe these partitioning reactions include chemisorption and precipitation. Chemisorption is inclusive of the suit...

  5. Adverse reactions to sulfites

    Science.gov (United States)

    Yang, William H.; Purchase, Emerson C.R.

    1985-01-01

    Sulfites are widely used as preservatives in the food and pharmaceutical industries. In the United States more than 250 cases of sulfite-related adverse reactions, including anaphylactic shock, asthmatic attacks, urticaria and angioedema, nausea, abdominal pain and diarrhea, seizures and death, have been reported, including 6 deaths allegedly associated with restaurant food containing sulfites. In Canada 10 sulfite-related adverse reactions have been documented, and 1 death suspected to be sulfite-related has occurred. The exact mechanism of sulfite-induced reactions is unknown. Practising physicians should be aware of the clinical manifestations of sulfite-related adverse reactions as well as which foods and pharmaceuticals contain sulfites. Cases should be reported to health officials and proper advice given to the victims to prevent further exposure to sulfites. The food industry, including beer and wine manufacturers, and the pharmaceutical industry should consider using alternative preservatives. In the interim, they should list any sulfites in their products. PMID:4052897

  6. Allergic reactions in anaesthesia

    DEFF Research Database (Denmark)

    Krøigaard, M; Garvey, L H; Menné, T;

    2005-01-01

    BACKGROUND: The aim of this retrospective survey of possible allergic reactions during anaesthesia was to investigate whether the cause suspected by anaesthetists involved corresponded with the cause found on subsequent investigation in the Danish Anaesthesia Allergy Centre (DAAC). METHODS: Case...... notes and anaesthetic charts from 111 reactions in 107 patients investigated in the DAAC were scrutinized for either suspicions of or warnings against specific substances stated to be the cause of the supposed allergic reaction. RESULTS: In 67 cases, one or more substances were suspected. In 49...... match, the right substance being suspected, but investigations showed an additional allergen or several substances, including the right substance being suspected. CONCLUSIONS: An informed guess is not a reliable way of determining the cause of a supposed allergic reaction during anaesthesia and may put...

  7. Oxygen evolution reaction catalysis

    Science.gov (United States)

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

    2016-09-06

    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  8. Meson production in + reactions

    Indian Academy of Sciences (India)

    H Machner; M Betigeri; J Bojowald; A Budzanowski; A Chatterjee; J Ernst; L Freindl; D Frekers; W Garske; K Grewer; A Hamacher; J Ilieva; L Jarczyk; K Kilian; S Kliczewski; W Klimala; D Kolev; T Kutsarova; J Lieb; H Machner; A Magiera; H Nann; L Pentchev; H S Plendl; D Protić; B Razen; P Von Rossen; B J Roy; R Siudak; J Smyrski; R V Srikantiah; A Strzałkowski; R Tsenov; K Zwoll

    2001-08-01

    Total and differential cross sections for the reactions $p+d → 3He + 0 with = ; and + → 3H + + were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon resonance. For both reactions a strong forward–backward asymmetry was found. The data were compared with model calculations. The aspect of isospin symmetry breaking is studied.

  9. Adverse reactions to sulfites

    OpenAIRE

    Yang, William H; Purchase, Emerson C.R.

    1985-01-01

    Sulfites are widely used as preservatives in the food and pharmaceutical industries. In the United States more than 250 cases of sulfite-related adverse reactions, including anaphylactic shock, asthmatic attacks, urticaria and angioedema, nausea, abdominal pain and diarrhea, seizures and death, have been reported, including 6 deaths allegedly associated with restaurant food containing sulfites. In Canada 10 sulfite-related adverse reactions have been documented, and 1 death suspected to be su...

  10. Measurement of the $pn \\to pp\\pi^0\\pi^-$ Reaction in Search for the Recently Observed Resonance Structure in $d\\pi^0\\pi^0$ and $d\\pi^+\\pi^-$ systems

    CERN Document Server

    Adlarson, P; Bardan, W; Bashkanov, M; Bergmann, F S; Berłowski, M; Bhatt, H; Büscher, M; Calén, H; Ciepał, I; Clement, H; Coderre, D; Czerwiński, E; Demmich, K; Doroshkevich, E; Engels, R; Erven, W; Eyrich, W; Fedorets, P; Föhl, K; Fransson, K; Goldenbaum, F; Goslawski, P; Goswami, A; Grigoryev, K; Gullström, C --O; Hauenstein, F; Heijkenskjöld, L; Hejny, V; Hinterberger, F; Hodana, M; Höistad, B; Jany, A; Jany, B R; Jarczyk, L; Johansson, T; Kamys, B; Kemmerling, G; Khan, F A; Khoukaz, A; Kirillov, D A; Kistryn, S; Klaja, J; Kleines, H; Kłos, B; Krapp, M; Krzemień, W; Kulessa, P; Kupść, A; Lalwani, K; Lersch, D; Li, L; Lorentz, B; Magiera, A; Maier, R; Marciniewski, P; Mariański, B; Mikirtychiants, M; Morsch, H --P; Moskal, P; Nandi, B K; Ohm, H; Ozerianska, I; del Rio, E Perez; Piskunov, N M; Pluciński, P; Podkopał, P; Prasuhn, D; Pricking, A; Pszczel, D; Pysz, K; Pyszniak, A; Redmer, C F; Ritman, J; Roy, A; Rudy, Z; Sawant, S; Schmidt, A; Schadmand, S; Sefzick, T; Serdyuk, V; Shah, N; Siemaszko, M; Siudak, R; Skorodko, T; Skurzok, M; Smyrski, J; Sopov, V; Stassen, R; Stepaniak, J; Stephan, E; Sterzenbach, G; Stockhorst, H; Ströher, H; Szczurek, A; Tolba, T; Trzciński, A; Varma, R; Wagner, G J; Węglorz, W; Wolke, M; Wro{ń}ska, A; Wüstner, P; Wurm, P; Yamamoto, A; Yuan, X; Zabierowski, J; Zheng, C; Zieliński, M J; Zipper, W; Złomańczuk, J; {Ż}uprański, P; {Ż}urek, M

    2013-01-01

    Exclusive measurements of the quasi-free $pn \\to pp\\pi^0\\pi^-$ reaction have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\\sqrt s$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated resonance structure. No ABC effect, {\\it i.e.} low-mass enhancement is found in the $\\pi^0\\pi^-$-invariant mass spectrum -- in agreement with the constraint from Bose statistics that the isovector pion pair can not be in relative s-wave. At the upper end of the covered energy region $t$-channel processes for Roper, $\\Delta(1600)$ and $\\Delta\\Delta$ excitations provide a reasonable description of the data, but at low energies the measured cross sections are much larger than predicted by such processes. Adding a resonance amplitude for the resonance at $m$=~2.37 GeV with $\\Gamma$ =~70 MeV and $I(J^P)=~0(3^+)$ observed recently in $pn \\to d\\pi^0\\pi^0$ and $pn \\to...

  11. Immediate reaction to clarithromycin.

    Science.gov (United States)

    Gangemi, S; Ricciardi, L; Fedele, R; Isola, S; Purello-D'Ambrosio, F

    2001-01-01

    We present the case of bronchospastic reaction to clarithromycin had during a drug challenge test. Personal allergic history was negative for respiratory allergies and positive for adverse drug reactions to general and regional anesthesia and to ceftriaxone. After the administration of 1/4 of therapeutic dose of clarithromycin the patient showed dyspnea, cough and bronchospasm in all the lung fields. The positivity of the test was confirmed by the negativity to the administration of placebo. The quickness and the clinical characteristic of the adverse reaction suggest a pathogenic mechanism of immediate-type hypersensitivity. On reviewing the literature we have found no reports of bronchospastic reaction to clarithromycin. Macrolides are a class of antibiotics mainly used in the last years in place of beta-lactams because of a broad spectrum of action and a low allergic power. In fact, there are few reports on allergic reactions to these molecules. Clarithromycin is one of the latest macrolides, characterised by the presence of a 14-carbon-atom lactone ring as erythromycin, active on a wide spectrum of pathogens.

  12. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  13. AF-Embedding of Crossed Products of Certain Graph C*-algebras by Quasi-free Actions(II)

    Institute of Scientific and Technical Information of China (English)

    Xiao Chun FANG

    2011-01-01

    Let E be a row-finite directed graph,let G be a locally compact abelian group with dual group(G)=Γ,let ω be a labeling map from E* to Γ,and let(C*(E),G,αω)be the C*-dynamical system definedby ω.Some mappings concerning the AF-embedding construction of C*(E)×αω G are studied in more detail.Several necessary conditions of AF-embedding and some properties of almost proper labeling map are obtained.Moreover it is proved that if E is constructed by attaching some 1-loops to a directed graph T consisting of some rooted directed trees and G is compact,then ω is almost proper,that is a sufficient condition for AF-embedding,if and only if ∑jk=1ωγj≠1Γ for any loop γi,γ2,……,γkattached to one path in T.

  14. eta and eta' meson production in the quasi-free proton-neutron collisions at the COS-11 facility

    CERN Document Server

    Czyzykiewicz, R

    2002-01-01

    Both, the structure of the eta' meson as well as its production mechanism are still under strong discussion and debate. The most possible hypothesis concerning the explanation of the almost three times larger mass for this meson observed experimentally relative to the theoretically calculated mass is a gluonium admixture to the eta' wave function. This gluonium admixture should reflect itself in the production yield of the eta' meson in proton-neutron collisions. Since the production of eta' meson through the gluonium exchange is isospin independent, the ratio R subeta = sigma(pn->pn eta)/sigma(pp->pp eta) close to threshold is expected to be R subeta = 1, after corrections for initial and final state interactions. The close to threshold eta' production in proton-proton collisions has already been investigated at the COSY-11 facility. Cross section values in the threshold region have been measured. However, until now no data have been taken for the eta' meson production in the proton-neutron collision. In ord...

  15. The electronic structure of quasi-free-standing germanene on monolayer MX (M = Ga, In; X = S, Se, Te).

    Science.gov (United States)

    Ni, Zeyuan; Minamitani, Emi; Ando, Yasunobu; Watanabe, Satoshi

    2015-07-15

    For the first time by using the ab initio density functional theory, the stability and electronic structures of germanene on monolayer GaS, GaSe, GaTe and InSe have been investigated. Germanene preserves its buckled-honeycomb structure on all the studied substrates similar to the free-standing case. Moreover, germanene stays neutral and preserves its Dirac-cone-like band structure on monolayer GaTe and InSe. In these two cases, a bandgap of 0.14-0.16 eV opens at the Dirac point of germanene, while the effective masses remain as small as 0.05-0.06 times the free-electron mass. The estimated carrier mobility is up to 2.2 × 10(5) cm(2) V(-1) s(-1). These features show that monolayer GaTe and InSe are promising as substrates for germanene devices.

  16. Reaction Qualifications Revisited

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2009-01-01

    of merit. Specifically, it preserves symmetry between negative evaluations of antimeritocratic bases of selection and negative evaluations of qualifications rooted in comparable antimeritocratic reactions. So if employers should not select among applicants on the basis of their (the employers') racial...... preferences, recipients should not respond to the applicant actually hired on the basis of their (the recipients') racial preferences. My account decomposes the meritocratic ideal into four separate norms, one of which applies to recipients rather than to selectors. Finally, it defends the view that reaction...... reaction-qualifications are entirely irrelevant from the point of view of merit, the view expounded here implies that the ideal of meritocracy and the norm of non-discrimination are less closely tied than theorists like Andrew Mason and David Miller believe.  ...

  17. Nanoparticle Reactions on Chip

    Science.gov (United States)

    Köhler, J. M.; Kirner, Th.; Wagner, J.; Csáki, A.; Möller, R.; Fritzsche, W.

    The handling of heterogenous systems in micro reactors is difficult due to their adhesion and transport behaviour. Therefore, the formation of precipitates and gas bubbles has to be avoided in micro reaction technology, in most cases. But, micro channels and other micro reactors offer interesting possibilities for the control of reaction conditions and transport by diffusion and convection due to the laminar flow caused by small Reynolds numbers. This can be used for the preparation and modification of objects, which are much smaller than the cross section of microchannels. The formation of colloidal solutions and the change of surface states of nano particles are two important tasks for the application of chip reactors in nanoparticle technology. Some concepts for the preparation and reaction of nanoparticles in modular chip reactor arrangements will be discussed.

  18. Inflammatory reaction in chondroblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Yamamura, Sigeki [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Sato, Keiji [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Sugiura, Hideshi [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Iwata, Hisashi [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan)

    1996-05-01

    The objective of this study was to evaluate the inflammatory reaction accompanying chondroblastoma and to define the value of the finding in clinical practice. We reviewed the clinical, radiographic, and magnetic resonance (MR) findings in six patients with histologically proven chondroblastoma. In all cases, MR imaging showered marrow and soft tissue edema. In four of six cases, periosteal reaction related to intra-osseous edema was more clearly demonstrated on MR imaging than on radiographs. Follow-up MR studies after surgery were available in three patients and all showed disappearance of inflammatory responses such as marrow and soft tissue edema, and reactive synovitis. We propose that these inflammatory reactions of chondroblastomas are inportant signs for detecting residual tumor in recurrences after surgery, as well as for making a precise diagnosis. The MR changes may also be valuable in demonstrating eradication of the tumor. (orig./MG)

  19. Hipersensitivity Reactions to Corticosteroids.

    Science.gov (United States)

    Berbegal, L; DeLeon, F J; Silvestre, J F

    2016-03-01

    Corticosteroids are widely used drugs in the clinical practice, especially by topic application in dermatology. These substances may act as allergens and produce immediate and delayed hypersensitivity reactions. Allergic contact dermatitis is the most frequent presentation of corticosteroid allergy and it should be studied by patch testing in specific units. The corticosteroids included in the Spanish standard battery are good markers but not ideal. Therefore, if those makers are positive, it is useful to apply a specific battery of corticosteroids and the drugs provided by patients. Immediate reactions are relatively rare but potentially severe, and it is important to confirm the sensitization profile and to guide the use of alternative corticosteroids, because they are often necessary in several diseases. In this article we review the main concepts regarding these two types of hypersensitivity reactions in corticosteroid allergy, as well as their approach in the clinical practice. Copyright © 2015 Elsevier España, S.L.U. and AEDV. All rights reserved.

  20. Adverse reactions to cosmetics

    Directory of Open Access Journals (Sweden)

    Dogra A

    2003-03-01

    Full Text Available Adverse reaction to cosmetics constitute a small but significant number of cases of contact dermatitis with varied appearances. These can present as contact allergic dermatitis, photodermatitis, contact irritant dermatitis, contact urticaria, hypopigmentation, hyperpigmentotion or depigmentation, hair and nail breakage. Fifty patients were included for the study to assess the role of commonly used cosmetics in causing adverse reactions. It was found that hair dyes, lipsticks and surprisingly shaving creams caused more reaction as compared to other cosmetics. Overall incidence of contact allergic dermatitis seen was 3.3% with patients own cosmetics. Patch testing was also done with the basic ingredients and showed positive results in few cases where casual link could be established. It is recommended that labeling of the cosmetics should be done to help the dermatologists and the patients to identify the causative allergen in cosmetic preparation.

  1. Knockout reactions: experimental aspects

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D. [Santiago de Compostela Univ. (Spain)

    2007-07-01

    The availability of radioactive beams has given rise to intense activity in the field of direct reactions. The removal of one(two)-nucleon (referred to as nucleon knockout in this text) from a fast exotic projectile has been extensively investigated. This lecture provides a general overview of the experimental results achieved using this technique. The sensitivity of the method to different experimental aspects is illustrated with a few examples. Special attention is given to the application of nucleon-knockout reactions as a general purpose spectroscopic tool. (author)

  2. Enantioselective Vinylogous Organocascade Reactions.

    Science.gov (United States)

    Hepburn, Hamish B; Dell'Amico, Luca; Melchiorre, Paolo

    2016-08-01

    Cascade reactions are powerful tools for rapidly assembling complex molecular architectures from readily available starting materials in a single synthetic operation. Their marriage with asymmetric organocatalysis has led to the development of novel techniques, which are now recognized as reliable strategies for the one-pot enantioselective synthesis of stereochemically dense molecules. In recent years, even more complex synthetic challenges have been addressed by applying the principle of vinylogy to the realm of organocascade catalysis. The key to the success of vinylogous organocascade reactions is the unique ability of the chiral organocatalyst to transfer reactivity to a distal position without losing control on the stereo-determining events. This approach has greatly expanded the synthetic horizons of the field by providing the possibility of forging multiple stereocenters in remote positions from the catalyst's point of action with high selectivity, while simultaneously constructing multiple new bonds. This article critically describes the developments achieved in the field of enantioselective vinylogous organocascade reactions, charting the ideas, the conceptual advances, and the milestone reactions that have been essential for reaching highly practical levels of synthetic efficiency.

  3. Explaining competitive reaction effects

    NARCIS (Netherlands)

    Leeflang, P.S.H.; Wittink, D.R.

    Changes in promotional expenditure decisions for a brand, as in other marketing decisions, should be based on the expected impact on purchase and consumption behavior as well as on the likely reactions by competitors. Purchase behavior may be predicted from estimated demand functions. Competitive

  4. Reaction product imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, D.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

  5. Cluster knockout reactions

    Indian Academy of Sciences (India)

    Arun K Jain; B N Joshi

    2014-04-01

    Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it were existing as a free entity. Theoretically, the relatively softer interactions of the two outgoing particles with the residual nucleus lead to optical distortions and are treated in terms of distorted wave (DW) formalism. The long-range projectile–cluster interaction is accounted for, in terms of the finite range (FR) direct reaction formalism, as against the more commonly adopted zero-range (ZR) distorted wave impulse approximation (DWIA) formalism. Comparison of the DWIA calculations with the observed data provide information about the momentum distribution and the clustering spectroscopic factor of the target nucleus. Interesting results and some recent advancements in the area of (, 2) reactions and heavy cluster knockout reactions are discussed. Importance of the finite-range vertex and the final-state interactions are brought out.

  6. Reaction Formulation: A Bibliography.

    Science.gov (United States)

    Pedrini, D. T.; Pedrini, Bonnie C.

    Reaction formation was studied by Sigmund Freud. This defense mechanism may be related to repression, substitution, reversal, and compensation (or over-compensation). Alfred Adler considered compensation a basic process in his individual psychology. Anna Freud discussed some defense mechanisms, and Bibring, Dwyer, Huntington, and Valenstein…

  7. Explaining competitive reaction effects

    NARCIS (Netherlands)

    Leeflang, P.S.H.; Wittink, D.R.

    2001-01-01

    Changes in promotional expenditure decisions for a brand, as in other marketing decisions, should be based on the expected impact on purchase and consumption behavior as well as on the likely reactions by competitors. Purchase behavior may be predicted from estimated demand functions. Competitive re

  8. HF Chain Reaction Laser

    Science.gov (United States)

    1975-05-01

    reaction can develop uni2ormly in a subsonic flow with snall teemperatiu-e rise over a distance much longer than the time for mixing, thus tendiný to isolate...upper level population, moreover, the observed effects of H2, Tabla 3, appear to be predicted reasonably well by the model. In the calcula- tions 112

  9. Reactions of Negative Ions

    Science.gov (United States)

    1984-07-17

    2 + H2 SO 4 + HS04 (HNO 3 ) 2 + HNO 3 1.1 0.6 * defined as 1 The most important results from an atmospheric viewpoint are the reactions of H SO with NO...constant HS04 >4.5 bracketing 22 0 C1 , 1.95 * 0.25 bracketlng 32 -4 __.. . .___,_=____,,_______... . . . -- . . . . One particularly interesting aspect of

  10. The Gewald multicomponent reaction

    NARCIS (Netherlands)

    Huang, Yijun; Doemling, Alexander

    2011-01-01

    The Gewald reaction of sulfur, cyanoacetic acid derivatives, and oxo-component (G-3CR) yielding highly substituted 2-aminothiophene derivatives has seen diverse applications in combinatorial and medicinal chemistry. Its products are of great use in pharmaceutical industry mainly as small molecular w

  11. EXERCISE AND REACTION TIMES

    Directory of Open Access Journals (Sweden)

    Varun

    2015-03-01

    Full Text Available OBJECTIVES: Physical exercise provides multiple benefits to an individual. It is known that exercising regularly can prevent coronary heart disease, hypertension and obesity and improve flexibility. The effect of exercise on visual reaction time needs to be studied, a s the existing data on the benefit of aerobic exercise on psychomotor functions is insufficient. MATERIALS AND METHODS: Online Visual reaction time is measured before and after exercise. Subjects were instructed to run on the spot with a springy step in ex aggerated motion for 50 to 60 counts at 2 counts per second, maintaining a constant rhythm. RESULTS: We observed that reaction time was significantly lower after performance of exercise. Individuals reported improved mental alertness, feel good factor, bet ter mood and increase circulation. CONCLUSION: Improving reaction times in sports can help the athlete to optimize his performance in making decisions and increasing attention span for example getting off the starting blocks sooner or successfully making c ontact with the ball. In addition this study shows that use of physical exercise helps improve cognitive function. Exercise proves to be a cheap non pharmacological alternative to improve cognitive performance.

  12. The human acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    H.W.G.Baker; D.Y.Liu; C.Garrett; M.Martic

    2000-01-01

    We developed tests of sperm-oocyte interaction: sperm-zona binding, zona-induced acrosome reaction, spermzona penetration and sperm-oolemma binding, using oocytes which failed to fertilise in clinical in vitro fertilization (IVF). Although oocyte defects contribute to failure of sperm oocyte interaction, rarely are all oocytes from one woman affected. Low or zero fertilization in standard IVFwas usually caused by sperm abnormalities. Poor sperm-zona pellucida binding was frequently associated with failure of standard IVF and obvious defects of sperm motility or morphology. The size and shape of the acrosome is particularly important for sperm binding to the oocyte. The proportion of acrosome intact sperm in the insemination medium was related to the IVF rate. Inducing the acrosome reaction with a calcium ionophore reduced sperm-zona binding. Blocking acrosome dispersal with an acrosin inhibitor prevented spermzona penetration. Sperm-zona penetration was even more highly related to IVF rates than was sperm-zona binding. Some patients had low or zero fertilization rates with standard IVF but normal sperm by conventional tests and normal sperm-zona binding. Few of their sperm underwent the acrosome reaction on the surface of the zona and none penetrated the zona. In contrast, fertilization and pregnancy rates were high with intracytoplasmic sperm injection. We call thiscondition defective zona pellucida induced acrosome reaction. Discovery of the nature of the abnormalities in the signal transduction and effector pathways of the human zona pellucida induced acrosome reaction should result in simpler tests and treatments for the patients and also provide new leads for contraceptive development.

  13. Inorganic Reaction Mechanisms. Part I

    Science.gov (United States)

    Cooke, D. O.

    1976-01-01

    Provides a collection of data on the mechanistic aspects of inorganic chemical reactions. Wherever possible includes procedures for classroom demonstration or student project work. The material covered includes gas phase reactions, reactions in solution, mechanisms of electron transfer, the reaction between iron III and iodine, and hydrolysis. (GS)

  14. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  15. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  16. Photooxidative reactions of psoralens

    Energy Technology Data Exchange (ETDEWEB)

    Potapenko, A.Ya.; Sukhorukov, V.L. (Vtoroj Moskovskij Gosudarstvennyj Meditsinskij Inst. (USSR))

    1984-08-31

    The mechanism and biological significance of photooxidative reactions of psoralens are reviewed. Skin-photosensitizing activities of bifunctional and monofunctional psoralens are compared. Antioxidants tocopherols and butilated hydroxytoluene inhibit photochemical reactions of psoralens responsible for induction of erythema. The same antioxidants do not inhibit PUVA-therapy of psriasis. Though psoralens can generate singlet oxygen under UVA-irradiation (315 - 400 nm), nevertheless singlet oxygen does not play a significant role in 8-methoxypsoralen (8-MOP) sensitized photooxidation of tocopherol or dihydroxyphenylalanine (DOPA). SH-compounds enhance the rate of 8-MOP sensitized photooxidation of DOPA by a factor of four, simultaneously the rate of oxidation of SH-groups is enhanced many fold in the presence of DOPA. Under UVA-irradiation in organic solvents psoralens are photooxidized. Dimeric photooxidized psoralens are easily destructed in water medium, their destruction induce oxidation of unsaturated lipids and DOPA.

  17. Photochemical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)

    1993-12-01

    The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.

  18. Well sealing via thermite reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, William Edward; Dunn, Sandra Dalvit

    2016-11-15

    A platform is formed in a well below a target plug zone by lowering a thermite reaction charge into the well and igniting it, whereby the products of the reaction are allowed to cool and expand to form a platform or support in the well. A main thermite reaction charge is placed above the platform and ignited to form a main sealing plug for the well. In some embodiments an upper plug is formed by igniting an upper thermite reaction charge above the main thermite reaction charge. The upper plug confines the products of ignition of the main thermite reaction charge.

  19. Insect bite reactions

    Directory of Open Access Journals (Sweden)

    Sanjay Singh

    2013-01-01

    Full Text Available Insects are a class of living creatures within the arthropods. Insect bite reactions are commonly seen in clinical practice. The present review touches upon the medically important insects and their places in the classification, the sparse literature on the epidemiology of insect bites in India, and different variables influencing the susceptibility of an individual to insect bites. Clinical features of mosquito bites, hypersensitivity to mosquito bites Epstein-Barr virus NK (HMB-EBV-NK disease, eruptive pseudoangiomatosis, Skeeter syndrome, papular pruritic eruption of HIV/AIDS, and clinical features produced by bed bugs, Mexican chicken bugs, assassin bugs, kissing bugs, fleas, black flies, Blandford flies, louse flies, tsetse flies, midges, and thrips are discussed. Brief account is presented of the immunogenic components of mosquito and bed bug saliva. Papular urticaria is discussed including its epidemiology, the 5 stages of skin reaction, the SCRATCH principle as an aid in diagnosis, and the recent evidence supporting participation of types I, III, and IV hypersensitivity reactions in its causation is summarized. Recent developments in the treatment of pediculosis capitis including spinosad 0.9% suspension, benzyl alcohol 5% lotion, dimethicone 4% lotion, isopropyl myristate 50% rinse, and other suffocants are discussed within the context of evidence derived from randomized controlled trials and key findings of a recent systematic review. We also touch upon a non-chemical treatment of head lice and the ineffectiveness of egg-loosening products. Knockdown resistance (kdr as the genetic mechanism making the lice nerves insensitive to permethrin is discussed along with the surprising contrary clinical evidence from Europe about efficacy of permethrin in children with head lice carrying kdr-like gene. The review also presents a brief account of insects as vectors of diseases and ends with discussion of prevention of insect bites and some

  20. Organocatalytic Enantioselective Henry Reactions

    Directory of Open Access Journals (Sweden)

    Raquel P. Herrera

    2011-05-01

    Full Text Available A large number of interesting organocatalytic enantioselective protocols have been explored and successfully applied in the last decade. Among them, the Henry (nitroaldol reaction represents a powerful carbon-carbon bond-forming procedure for the preparation of valuable synthetic intermediates, such as enantioenriched nitro alcohols, which can be further transformed in a number of important nitrogen and oxygen-containing compounds. This area of research is still in expansion and a more complex version of this useful process has recently emerged, the domino Michael/Henry protocol, affording highly functionalized cycles with multiple stereogenic centers.

  1. Multispecies pair annihilation reactions.

    Science.gov (United States)

    Deloubrière, Olivier; Hilhorst, Henk J; Täuber, Uwe C

    2002-12-16

    We consider diffusion-limited reactions A(i)+A(j)--> (12 and d> or =2, we argue that the asymptotic density decay for such mutual annihilation processes with equal rates and initial densities is the same as for single-species pair annihilation A+A-->. In d=1, however, particle segregation occurs for all q< infinity. The total density decays according to a q dependent power law, rho(t) approximately t(-alpha(q)). Within a simplified version of the model alpha(q)=(q-1)/2q can be determined exactly. Our findings are supported through Monte Carlo simulations.

  2. Low Energy Nuclear Reactions?

    CERN Document Server

    CERN. Geneva; Faccini, R.

    2014-01-01

    After an introduction to the controversial problem of Low Energy Nuclear Reactions (LENR) catalyzed by neutrons on metallic hydride surfaces we present the results of an experiment, made in collaboration with ENEA Labs in Frascati, to search neutrons from plasma discharges in electrolytic cells. The negative outcome of our experiment goes in the direction of ruling out those theoretical models expecting LENR to occur in condensed matter systems under specific conditions. Our criticism on the theoretical foundations of such models will also be presented.

  3. Organic chemistry: Reactions triggered electrically

    Science.gov (United States)

    Xiang, Limin; Tao, N. J.

    2016-03-01

    Single-molecule experiments have revealed that chemical reactions can be controlled using electric fields -- and that the reaction rate is sensitive to both the direction and the strength of the applied field. See Letter p.88

  4. Theoretical Studies of Reaction Surfaces

    Science.gov (United States)

    2007-11-02

    Similar levels of agreement are being found in studies of water clusters12 , the Menshutkin reaction 13 (ion separation reaction ), a prototypical SN2 ...of both reactants and products. These analyses reveal that Bery pseudorotation occurs repeatedly during the side attack, whereas the SN2 reaction H...31 Aug 97 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS AASERT93 THEORETICAL STUDIES OF REACTION SURFACES F49620-93-1-0556 3484/XS 6. AUTHOR(S) 61103D DR

  5. Orbital Energy-Based Reaction Analysis of SN2 Reactions

    Directory of Open Access Journals (Sweden)

    Takao Tsuneda

    2016-07-01

    Full Text Available An orbital energy-based reaction analysis theory is presented as an extension of the orbital-based conceptual density functional theory. In the orbital energy-based theory, the orbitals contributing to reactions are interpreted to be valence orbitals giving the largest orbital energy variation from reactants to products. Reactions are taken to be electron transfer-driven when they provide small variations for the gaps between the contributing occupied and unoccupied orbital energies on the intrinsic reaction coordinates in the initial processes. The orbital energy-based theory is then applied to the calculations of several S N2 reactions. Using a reaction path search method, the Cl− + CH3I → ClCH3 + I− reaction, for which another reaction path called “roundabout path” is proposed, is found to have a precursor process similar to the roundabout path just before this SN2 reaction process. The orbital energy-based theory indicates that this precursor process is obviously driven by structural change, while the successor SN2 reaction proceeds through electron transfer between the contributing orbitals. Comparing the calculated results of the SN2 reactions in gas phase and in aqueous solution shows that the contributing orbitals significantly depend on solvent effects and these orbitals can be correctly determined by this theory.

  6. Mass Transfer with Chemical Reaction.

    Science.gov (United States)

    DeCoursey, W. J.

    1987-01-01

    Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

  7. Mass Transfer with Chemical Reaction.

    Science.gov (United States)

    DeCoursey, W. J.

    1987-01-01

    Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

  8. Reaction Decoder Tool (RDT): extracting features from chemical reactions

    Science.gov (United States)

    Rahman, Syed Asad; Torrance, Gilliean; Baldacci, Lorenzo; Martínez Cuesta, Sergio; Fenninger, Franz; Gopal, Nimish; Choudhary, Saket; May, John W.; Holliday, Gemma L.; Steinbeck, Christoph; Thornton, Janet M.

    2016-01-01

    Summary: Extracting chemical features like Atom–Atom Mapping (AAM), Bond Changes (BCs) and Reaction Centres from biochemical reactions helps us understand the chemical composition of enzymatic reactions. Reaction Decoder is a robust command line tool, which performs this task with high accuracy. It supports standard chemical input/output exchange formats i.e. RXN/SMILES, computes AAM, highlights BCs and creates images of the mapped reaction. This aids in the analysis of metabolic pathways and the ability to perform comparative studies of chemical reactions based on these features. Availability and implementation: This software is implemented in Java, supported on Windows, Linux and Mac OSX, and freely available at https://github.com/asad/ReactionDecoder Contact: asad@ebi.ac.uk or s9asad@gmail.com PMID:27153692

  9. Reaction Decoder Tool (RDT): extracting features from chemical reactions.

    Science.gov (United States)

    Rahman, Syed Asad; Torrance, Gilliean; Baldacci, Lorenzo; Martínez Cuesta, Sergio; Fenninger, Franz; Gopal, Nimish; Choudhary, Saket; May, John W; Holliday, Gemma L; Steinbeck, Christoph; Thornton, Janet M

    2016-07-01

    Extracting chemical features like Atom-Atom Mapping (AAM), Bond Changes (BCs) and Reaction Centres from biochemical reactions helps us understand the chemical composition of enzymatic reactions. Reaction Decoder is a robust command line tool, which performs this task with high accuracy. It supports standard chemical input/output exchange formats i.e. RXN/SMILES, computes AAM, highlights BCs and creates images of the mapped reaction. This aids in the analysis of metabolic pathways and the ability to perform comparative studies of chemical reactions based on these features. This software is implemented in Java, supported on Windows, Linux and Mac OSX, and freely available at https://github.com/asad/ReactionDecoder : asad@ebi.ac.uk or s9asad@gmail.com. © The Author 2016. Published by Oxford University Press.

  10. The Glaser–Hay reaction

    DEFF Research Database (Denmark)

    Vilhelmsen, Mie Højer; Jensen, Jonas; Tortzen, Christian

    2013-01-01

    . This unfavorable change in reaction profile could be avoided by adding molecular sieves to the reaction mixture, thereby removing the water that is accumulated from the air and produced in the reaction in which dioxygen acts as the oxidizing agent. Not unexpectedly, the stirring rate, and hence uptake of air (O2...... on the scope of this reaction by using both 13C NMR and UV/Vis spectroscopic methods. The former method was used to study the kinetics of the coupling of aryl-substituted alkynes as the aryl carbon resonances of the reactants and products have similar NOEs and relaxation times. The reaction was found...

  11. Nuclear reactions an introduction

    CERN Document Server

    Paetz gen. Schieck, Hans

    2014-01-01

    Nuclei and nuclear reactions offer a unique setting for investigating three (and in some cases even all four) of the fundamental forces in nature. Nuclei have been shown – mainly by performing scattering experiments with electrons, muons, and neutrinos – to be extended objects with complex internal structures: constituent quarks; gluons, whose exchange binds the quarks together; sea-quarks, the ubiquitous virtual quark-antiquark pairs and, last but not least, clouds of virtual mesons, surrounding an inner nuclear region, their exchange being the source of the nucleon-nucleon interaction.   The interplay between the (mostly attractive) hadronic nucleon-nucleon interaction and the repulsive Coulomb force is responsible for the existence of nuclei; their degree of stability, expressed in the details and limits of the chart of nuclides; their rich structure and the variety of their interactions. Despite the impressive successes of the classical nuclear models and of ab-initio approaches, there is clearly no ...

  12. Laser induced nuclear reactions

    Science.gov (United States)

    Ledingham, Ken; McCanny, Tom; Graham, Paul; Fang, Xiao; Singhal, Ravi; Magill, Joe; Creswell, Alan; Sanderson, David; Allott, Ric; Neely, David; Norreys, Peter; Santala, Marko; Zepf, Matthew; Watts, Ian; Clark, Eugene; Krushelnick, Karl; Tatarakis, Michael; Dangor, Bucker; Machecek, Antonin; Wark, Justin

    1998-12-01

    Dramatic improvements in laser technology since 1984 have revolutionised high power laser technology. Application of chirped-pulse amplification techniques has resulted in laser intensities in excess of 1019W/cm2. In the mid to late eighties, C. K. Rhodes and K. Boyer discussed the possibility of shining laser light of this intensity onto solid surfaces and to cause nuclear transitions. In particular, irradiation of a uranium target could induce electro- and photofission in the focal region of the laser. In this paper it is shown that μCi of 62Cu can be generated via the (γ,n) reaction by a laser with an intensity of about 1019Wcm-2.

  13. Eikonal reaction theory

    CERN Document Server

    Yahiro, Masanobu; Minomo, Kosho

    2011-01-01

    We present an accurate method of treating the one-neutron removal reaction at intermediate incident energies induced by both nuclear and Coulomb interactions. In the method, the nuclear and Coulomb breakup processes are consistently treated by the method of continuum discretized coupled channels without making the adiabatic approximation to the Coulomb interaction, so that the removal cross section calculated never diverges. This method is applied to recently measured one-neutron removal cross section for $^{31}$Ne+$^{12}$C scattering at 230 MeV/nucleon and $^{31}$Ne+$^{208}$Pb scattering at 234 MeV/nucleon. The spectroscopic factor and the asymptotic normalization coefficient of the last neutron in $^{31}$Ne are evaluated.

  14. Hypersensitivity reaction with deferasirox

    Directory of Open Access Journals (Sweden)

    Atul Sharma

    2015-01-01

    Full Text Available Thalassemias comprise a group of hereditary blood disorders. Thalassemia major presents with anemia within the first 2 years of life requiring frequent blood transfusions for sustaining life. Regular blood transfusions lead to iron overload-related complications. Prognosis of thalassemia has improved because of the availability of iron-chelating agents. Oral iron chelators are the mainstay of chelation therapy. Deferasirox is a new-generation oral iron chelator for once daily usage. We herein describe a patient of beta thalassemia major who developed an allergic manifestation in the form of erythematous pruritic skin rashes to the oral iron chelator deferasirox. This is a rare adverse reaction reported with deferasirox that led to a therapeutic dilemma in this particular case.

  15. Hypersensitivity reaction with deferasirox.

    Science.gov (United States)

    Sharma, Atul; Arora, Ekta; Singh, Harmanjit

    2015-01-01

    Thalassemias comprise a group of hereditary blood disorders. Thalassemia major presents with anemia within the first 2 years of life requiring frequent blood transfusions for sustaining life. Regular blood transfusions lead to iron overload-related complications. Prognosis of thalassemia has improved because of the availability of iron-chelating agents. Oral iron chelators are the mainstay of chelation therapy. Deferasirox is a new-generation oral iron chelator for once daily usage. We herein describe a patient of beta thalassemia major who developed an allergic manifestation in the form of erythematous pruritic skin rashes to the oral iron chelator deferasirox. This is a rare adverse reaction reported with deferasirox that led to a therapeutic dilemma in this particular case.

  16. Nuclear reactions in astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, M.; Rayet, M. (Universite Libre de Bruxelles (BE))

    1990-06-01

    At all times and at all astrophysical scales, nuclear reactions have played and continue to play a key role. This concerns the energetics as well as the production of nuclides (nucleosynthesis). After a brief review of the observed composition of various objects in the universe, and especially of the solar system, the basic ingredients that are required in order to build up models for the chemical evolution of galaxies are sketched. Special attention is paid to the evaluation of the stellar yields through an overview of the important burning episodes and nucleosynthetic processes that can develop in non-exploding or exploding stars. Emphasis is put on the remaining astrophysical and nuclear physics uncertainties that hamper a clear understanding of the observed characteristics, and especially compositions, of a large variety of astrophysical objects.

  17. Kinetics of Bio-Reactions

    DEFF Research Database (Denmark)

    2015-01-01

    his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions....... The models can be used in mass balances for design of processes under process conditions not yet studied experimentally. The value of the predictive kinetic model depends on the quality of the experimental data on which the model is based, and well-founded kinetic models for enzyme reactions have...... a considerable predictive power. This is also true for cell reaction models, when the model is used in its proper context. The chapter first discusses the kinetics for enzymatically catalyzed reactions (“enzyme reactions”). The kinetics can be derived from a mechanistic model. Then, the chapter derives empirical...

  18. Resonance Reaction in Diffusion-Influenced Bimolecular Reactions

    CERN Document Server

    Kolb, Jakob J; Dzubiella, Joachim

    2016-01-01

    We investigate the influence of a stochastically fluctuating step-barrier potential on bimolecular reaction rates by exact analytical theory and stochastic simulations. We demonstrate that the system exhibits a new resonant reaction behavior with rate enhancement if an appropriately defined fluctuation decay length is of the order of the system size. Importantly, we find that in the proximity of resonance the standard reciprocal additivity law for diffusion and surface reaction rates is violated due to the dynamical coupling of multiple kinetic processes. Together, these findings may have important repercussions on the correct interpretation of various kinetic reaction problems in complex systems, as, e.g., in biomolecular association or catalysis.

  19. Hemolytic Transfusion Reactions

    Directory of Open Access Journals (Sweden)

    Fatih Mehmet Azık

    2011-12-01

    Full Text Available The prevalence of fatal hemolytic transfusion reactions (HTRs is approximately 1:200000 per unit. Acute HTRs occur during or within 24 h after administration of a blood product. Transfusion of incompatible red blood cells (RBCs, and, more rarely, of a large volume of incompatible plasma usually are the causative agents. Delayed HTRs are caused by a secondary immune response to an antigen on the donor’s RBCs. Different mechanisms lead to intra- and extravascular hemolysis, such as complete complement activation, phagocytosis of RBCs covered with C3b by macrophages after incomplete complement activation, or destruction of RBCs covered only with IgG by direct cell to cell contact with K cells. The clinical consequences of HTRs are triggered via several pathophysiological pathways. Formation of anaphylatoxins, release of cytokines causing a systemic inflammatory response syndrome, activation of the kinin system, the intrinsic clotting cascade and fibrinolysis result in hypotension, disseminated intravascular coagulation, diffuse bleeding, and disruption of microcirculation leading to renal failure and shock. In this review, the symptoms of HTR are introduced, laboratory investigations and treatment are described, and some recommendations for prevention are given. (Journal of Current Pediatrics 2011; 9: 127-32

  20. NIF Gamma Reaction History

    Science.gov (United States)

    Herrmann, H. W.; Kim, Y.; Young, C. S.; Mack, J. M.; McEvoy, A. M.; Hoffman, N. M.; Wilson, D. C.; Langenbrunner, J. R.; Evans, S.; Batha, S. H.; Stoeffl, W.; Lee, A.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Malone, R. M.; Kaufman, M. I.

    2010-11-01

    The primary objective of the NIF Gamma Reaction History (GRH) diagnostics is to provide bang time and burn width information based upon measurement of fusion gamma-rays. This is accomplished with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. In addition, the GRH detectors can perform γ-ray spectroscopy to explore other nuclear processes from which additional significant implosion parameters may be inferred (e.g., plastic ablator areal density). Implementation is occurring in 2 phases: 1) four PMT-based channels mounted to the outside of the NIF target chamber at ˜6 m from TCC (GRH-6m) for the 3e13-3e16 DT neutron yield range expected during the early ignition-tuning campaigns; and 2) several channels located just inside the target bay shield wall at ˜15 m from TCC (GRH-15m) with optical paths leading through the wall into well-shielded streak cameras and PMTs for the 1e16-1e20 yield range expected during the DT ignition campaign. This suite of diagnostics will allow exploration of interesting γ-ray physics well beyond the ignition campaign. Recent data from OMEGA and NIF will be shown.

  1. The Progression of Sequential Reactions

    Directory of Open Access Journals (Sweden)

    Jack McGeachy

    2010-01-01

    Full Text Available Sequential reactions consist of linked reactions in which the product of the first reaction becomes the substrate of a second reaction. Sequential reactions occur in industrially important processes, such as the chlorination of methane. A generalized series of three sequential reactions was analyzed in order to determine the times at which each chemical species reaches its maximum. To determine the concentration of each species as a function of time, the differential rate laws for each species were solved. The solution of each gave the concentration curve of the chemical species. The concentration curves of species A1 and A2 possessed discreet maxima, which were determined through slope-analysis. The concentration curve of the final product, A3, did not possess a discreet maximum, but rather approached a finite limit.

  2. Microwave-Accelerated Organic Reactions

    Institute of Scientific and Technical Information of China (English)

    LU; TaJung

    2001-01-01

    The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted 1,3-dipolar cycloaddition reaction of nitrile oxides with allylic alcohols, the cleavage reaction of 1,3-diketones under alkaline conditions, and the formation of carbamates from isocyanates with alcohols. The reactions carried out under microwave irradiation, in general, required considerably less reaction time and afforded the desired products in higher yields than those under classical conditions. In all the cases we have studied, the procedures are simplified, the purity of the products are higher, and the cost of reaction is greatly reduced employing microwave.  ……

  3. Microwave-Accelerated Organic Reactions

    Institute of Scientific and Technical Information of China (English)

    LU TaJung

    2001-01-01

    @@ The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted 1,3-dipolar cycloaddition reaction of nitrile oxides with allylic alcohols, the cleavage reaction of 1,3-diketones under alkaline conditions, and the formation of carbamates from isocyanates with alcohols. The reactions carried out under microwave irradiation, in general, required considerably less reaction time and afforded the desired products in higher yields than those under classical conditions. In all the cases we have studied, the procedures are simplified, the purity of the products are higher, and the cost of reaction is greatly reduced employing microwave.

  4. Speeding chemical reactions by focusing

    CERN Document Server

    Lacasta, A M; Sancho, J M; Lindenberg, K

    2012-01-01

    We present numerical results for a chemical reaction of colloidal particles which are transported by a laminar fluid and are focused by periodic obstacles in such a way that the two components are well mixed and consequently the chemical reaction is speeded up. The roles of the various system parameters (diffusion coefficients, reaction rate, obstacles sizes) are studied. We show that focusing speeds up the reaction from the diffusion limited rate (t to the power -1/2) to very close to the perfect mixing rate, (t to the power -1).

  5. Radiation reaction in fusion plasmas.

    Science.gov (United States)

    Hazeltine, R D; Mahajan, S M

    2004-10-01

    The effects of a radiation reaction on thermal electrons in a magnetically confined plasma, with parameters typical of planned burning plasma experiments, are studied. A fully relativistic kinetic equation that includes the radiation reaction is derived. The associated rate of phase-space contraction is computed and the relative importance of the radiation reaction in phase space is estimated. A consideration of the moments of the radiation reaction force show that its effects are typically small in reactor-grade confined plasmas, but not necessarily insignificant.

  6. [Situational reactions in suicidologic practice].

    Science.gov (United States)

    Ambrumova, A G; Vrono, E M

    1985-01-01

    The paper is devoted to the description of suicidal manifestations in mentally normal adolescents among typical behavioural disorders characteristic of situational reactions of this age. Three types of suicido-dangerous situational responses of adolescents were specified with regard to their age and auto-and heteaggressiveness ratio: reaction of deprivation, explosive reaction and reaction of auto-elimination. Suicidogenic conflicts were analyzed and spheres of age-specific suicidal conflicts were defined. It is advisable that outpatient management of mentally normal adolescents with a history of a suicidal attempt be conducted in a special room of presentive suicidological service.

  7. Kinematically complete chemical reaction dynamics

    Science.gov (United States)

    Trippel, S.; Stei, M.; Otto, R.; Hlavenka, P.; Mikosch, J.; Eichhorn, C.; Lourderaj, U.; Zhang, J. X.; Hase, W. L.; Weidemüller, M.; Wester, R.

    2009-11-01

    Kinematically complete studies of molecular reactions offer an unprecedented level of insight into the dynamics and the different mechanisms by which chemical reactions occur. We have developed a scheme to study ion-molecule reactions by velocity map imaging at very low collision energies. Results for the elementary nucleophilic substitution (SN2) reaction Cl- + CH3I → ClCH3 + I- are presented and compared to high-level direct dynamics trajectory calculations. Furthermore, an improved design of the crossed-beam imaging spectrometer with full three-dimensional measurement capabilities is discussed and characterization measurements using photoionization of NH3 and photodissociation of CH3I are presented.

  8. Pathophysiology of hemolytic transfusion reactions.

    Science.gov (United States)

    Davenport, Robertson D

    2005-07-01

    Hemolytic transfusion reactions (HTR) are systemic reactions provoked by immunologic red blood cell (RBC) incompatibility. Clinical and experimental observations of such reactions indicate that they proceed through phases of humoral immune reaction, activation of phagocytes, productions of cytokine mediators, and wide-ranging cellular responses. HTR have many features in common with the systemic inflammatory response syndrome (SIRS). Knowledge of the pathophysiologic mechanisms in HTR suggest that newer biological agents that target complement intermediates or proinflammatory cytokines may be effective agents in the treatment of severe HTRs.

  9. Dynamic Reaction Figures: An Integrative Vehicle for Understanding Chemical Reactions

    Science.gov (United States)

    Schultz, Emeric

    2008-01-01

    A highly flexible learning tool, referred to as a dynamic reaction figure, is described. Application of these figures can (i) yield the correct chemical equation by simply following a set of menu driven directions; (ii) present the underlying "mechanism" in chemical reactions; and (iii) help to solve quantitative problems in a number of different…

  10. Progress in microscopic direct reaction modeling of nucleon induced reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dupuis, M.; Bauge, E.; Hilaire, S.; Lechaftois, F.; Peru, S.; Pillet, N.; Robin, C. [CEA, DAM, DIF, Arpajon (France)

    2015-12-15

    A microscopic nuclear reaction model is applied to neutron elastic and direct inelastic scatterings, and pre-equilibrium reaction. The JLM folding model is used with nuclear structure information calculated within the quasi-particle random phase approximation implemented with the Gogny D1S interaction. The folding model for direct inelastic scattering is extended to include rearrangement corrections stemming from both isoscalar and isovector density variations occurring during a transition. The quality of the predicted (n,n), (n,n{sup '}), (n,xn) and (n,n{sup '}γ) cross sections, as well as the generality of the present microscopic approach, shows that it is a powerful tool that can help improving nuclear reactions data quality. Short- and long-term perspectives are drawn to extend the present approach to more systems, to include missing reactions mechanisms, and to consistently treat both structure and reaction problems. (orig.)

  11. Microscopic effective reaction theory for deuteron-induced reactions

    CERN Document Server

    Neoh, Yuen Sim; Minomo, Kosho; Ogata, Kazuyuki

    2016-01-01

    The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model-space characterized by a $p+n+{\\rm A}$ three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by a microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A. The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels method (CDCC), and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on $^{58}$Ni and $^{208}$Pb target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

  12. Microscopic effective reaction theory for deuteron-induced reactions

    Science.gov (United States)

    Neoh, Yuen Sim; Yoshida, Kazuki; Minomo, Kosho; Ogata, Kazuyuki

    2016-10-01

    The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model space characterized by a p +n +A three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by a microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A . The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels (CDCC) method, and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on 58Ni and 208Pb target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

  13. Dicarbonyl Intermediates in the Maillard Reaction

    National Research Council Canada - National Science Library

    THORNALLEY, PAUL J

    2005-01-01

    A bstract : The complexity of the Maillard reaction arises partly from multiple fragmentation reactions of the sugar moiety, constituting branch points in the reaction progress and establishing many parallel reaction pathways...

  14. "Greening up" the Suzuki Reaction

    Science.gov (United States)

    Aktoudianakis, Evangelos; Chan, Elton; Edward, Amanda R.; Jarosz, Isabel; Lee, Vicki; Mui, Leo; Thatipamala, Sonya S.; Dicks, Andrew P.

    2008-01-01

    This article describes the rapid, green synthesis of a biaryl compound (4-phenylphenol) via a Pd(0)-catalyzed Suzuki cross-coupling reaction in water. Mild reaction conditions and operational simplicity makes this experiment especially amenable to both mid- and upper-level undergraduates. The methodology exposes students to purely aqueous…

  15. Limits for Stochastic Reaction Networks

    DEFF Research Database (Denmark)

    Cappelletti, Daniele

    Reaction systems have been introduced in the 70s to model biochemical systems. Nowadays their range of applications has increased and they are fruitfully used in dierent elds. The concept is simple: some chemical species react, the set of chemical reactions form a graph and a rate function is ass...

  16. Adverse Reactions to Hallucinogenic Drugs.

    Science.gov (United States)

    Meyer, Roger E. , Ed.

    This reports a conference of psychologists, psychiatrists, geneticists and others concerned with the biological and psychological effects of lysergic acid diethylamide and other hallucinogenic drugs. Clinical data are presented on adverse drug reactions. The difficulty of determining the causes of adverse reactions is discussed, as are different…

  17. Allergic reactions to insect secretions.

    Science.gov (United States)

    Pecquet, Catherine

    2013-01-01

    Some products derived from insects can induce allergic reactions. The main characteristics of some products from honeybees, cochineal and silkworms are summarised here. We review allergic reactions from honey-derived products (propolis, wax, royal jelly), from cochineal products (shellac and carmine) and from silk : clinical features, allergological investigations and allergens if they are known.

  18. Free Radical Reactions in Food.

    Science.gov (United States)

    Taub, Irwin A.

    1984-01-01

    Discusses reactions of free radicals that determine the chemistry of many fresh, processed, and stored foods. Focuses on reactions involving ascorbic acid, myoglobin, and palmitate radicals as representative radicals derived from a vitamin, metallo-protein, and saturated lipid. Basic concepts related to free radical structure, formation, and…

  19. Limits for Stochastic Reaction Networks

    DEFF Research Database (Denmark)

    Cappelletti, Daniele

    at a certain time are stochastically modelled by means of a continuous-time Markov chain. Our work concerns primarily stochastic reaction systems, and their asymptotic properties. In Paper I, we consider a reaction system with intermediate species, i.e. species that are produced and fast degraded along a path...... of the stochastic reaction systems. Specically, we build a theory for stochastic reaction systems that is parallel to the deciency zero theory for deterministic systems, which dates back to the 70s. A deciency theory for stochastic reaction systems was missing, and few results connecting deciency and stochastic....... Such species, in the deterministic modelling regime, assume always the same value at any positive steady state. In the stochastic setting, we prove that, if the initial condition is a point in the basin of attraction of a positive steady state of the corresponding deterministic model and tends to innity...

  20. [Anaphylactic reaction following hair bleaching].

    Science.gov (United States)

    Babilas, P; Landthaler, M; Szeimies, R-M

    2005-12-01

    Ammonium persulphate is a potent bleach and oxidizing agent that is commonly present in hair bleaches. Because bleaching is so commonly performed, hairdressers often develop allergic contact dermatitis to ammonium persulphate. In addition to this delayed reaction, asthma and rhinitis may develop as immediate reactions in those exposed to the fumes. Severe anaphylactic reactions are rare. We report a 24-year-old woman who acquired dermatitis following contact with bleaching substances while working as a hairdresser. After changing her profession, the dermatitis disappeared. Following the private use of a hairdressing bleach containing ammonium persulphate, she suffered a severe anaphylactic reaction with unconsciousness. The patient also developed an anaphylactic reaction three hours following patch testing with the hairdresser battery. The rub test with ammonium persulphate (2.5%) in a 1:100 solution was positive.

  1. Adverse reactions to drug additives.

    Science.gov (United States)

    Simon, R A

    1984-10-01

    There is a long list of additives used by the pharmaceutical industry. Most of the agents used have not been implicated in hypersensitivity reactions. Among those that have, only reactions to parabens and sulfites have been well established. Parabens have been shown to be responsible for rare immunoglobulin E-mediated reactions that occur after the use of local anesthetics. Sulfites, which are present in many drugs, including agents commonly used to treat asthma, have been shown to provoke severe asthmatic attacks in sensitive individuals. Recent studies indicate that additives do not play a significant role in "hyperactivity." The role of additives in urticaria is not well established and therefore the incidence of adverse reactions in this patient population is simply not known. In double-blind, placebo-controlled studies, reactions to tartrazine or additives other than sulfites, if they occur at all, are indeed quite rare for the asthmatic population, even for the aspirin-sensitive subpopulation.

  2. [Skin reactions to tattoo ink].

    Science.gov (United States)

    Piérard-Franchimont, C; Hermanns, J-F; Piérard, G E

    2011-01-01

    Ritual and artistic tattoos rely on the use of numerous pigments which are not all entirely inert once placed in the dermis. The compositions of some tattoo inks are identified. However, new but less well identified compounds appear on the market. Allergic reactions can be present under different aspects. They may correspond to allergic contact dermatitis or to photodermatitis. Other reactions include allergic hypersensitivity reactions as well as lichenoid, granulomatous or pseudolymphoma reactions. Pulsed light and laser are typically used for regular tattoo removal. These procedures are not indicated in inflamed tattoos. Indeed, the pigment dispersed during photolysis may perpetuate the reaction. Pseudotattoos due to the stratum corneum staining are frequently responsible for photoeczema.

  3. Reaction rates for reaction-diffusion kinetics on unstructured meshes

    Science.gov (United States)

    Hellander, Stefan; Petzold, Linda

    2017-02-01

    The reaction-diffusion master equation is a stochastic model often utilized in the study of biochemical reaction networks in living cells. It is applied when the spatial distribution of molecules is important to the dynamics of the system. A viable approach to resolve the complex geometry of cells accurately is to discretize space with an unstructured mesh. Diffusion is modeled as discrete jumps between nodes on the mesh, and the diffusion jump rates can be obtained through a discretization of the diffusion equation on the mesh. Reactions can occur when molecules occupy the same voxel. In this paper, we develop a method for computing accurate reaction rates between molecules occupying the same voxel in an unstructured mesh. For large voxels, these rates are known to be well approximated by the reaction rates derived by Collins and Kimball, but as the mesh is refined, no analytical expression for the rates exists. We reduce the problem of computing accurate reaction rates to a pure preprocessing step, depending only on the mesh and not on the model parameters, and we devise an efficient numerical scheme to estimate them to high accuracy. We show in several numerical examples that as we refine the mesh, the results obtained with the reaction-diffusion master equation approach those of a more fine-grained Smoluchowski particle-tracking model.

  4. Eikonal reaction theory for two-neutron removal reactions

    CERN Document Server

    Minomo, K; Egashira, K; Ogata, K; Yahiro, M

    2014-01-01

    The eikonal reaction theory (ERT) proposed lately is a method of calculating one-neutron removal reactions at intermediate incident energies in which Coulomb breakup is treated accurately with the continuum discretized coupled-channels method. ERT is extended to two-neutron removal reactions. ERT reproduces measured one- and two-neutron removal cross sections for 6He scattering on 12C and 208Pb targets at 240 MeV/nucleon and also on a 28Si target at 52 MeV/nucleon. For the heavier target in which Coulomb breakup is important, ERT yields much better agreement with the measured cross sections than the Glauber model.

  5. Drug hypersensitivity reactions involving skin.

    Science.gov (United States)

    Hausmann, Oliver; Schnyder, Benno; Pichler, Werner J

    2010-01-01

    Immune reactions to drugs can cause a variety of diseases involving the skin, liver, kidney, lungs, and other organs. Beside immediate, IgE-mediated reactions of varying degrees (urticaria to anaphylactic shock), many drug hypersensitivity reactions appear delayed, namely hours to days after starting drug treatment, showing a variety of clinical manifestations from solely skin involvement to fulminant systemic diseases which may be fatal. Immunohistochemical and functional studies of drug-specific T cells in patients with delayed reactions confirmed a predominant role for T cells in the onset and maintenance of immune-mediated delayed drug hypersensitivity reactions (type IV reactions). In these reactions, drug-specific CD4+ and CD8+ T cells are stimulated by drugs through their T cell receptors (TCR). Drugs can stimulate T cells in two ways: they can act as haptens and bind covalently to larger protein structures (hapten-carrier model), inducing a specific immune response. In addition, they may accidentally bind in a labile, noncovalent way to a particular TCR of the whole TCR repertoire and possibly also major histocompatibility complex (MHC)-molecules - similar to their pharmacologic action. This seems to be sufficient to reactivate certain, probably in vivo preactivated T cells, if an additional interaction of the drug-stimulated TCR with MHC molecules occurs. The mechanism was named pharmacological interaction of a drug with (immune) receptor and thus termed the p-i concept. This new concept may explain the frequent skin symptoms in drug hypersensitivity to oral or parenteral drugs. Furthermore, the various clinical manifestations of T cell-mediated drug hypersensitivity may be explained by distinct T cell functions leading to different clinical phenotypes. These data allowed a subclassification of the delayed hypersensitivity reactions (type IV) into T cell reactions which, by releasing certain cytokines and chemokines, preferentially activate and recruit

  6. Nuclear reactions at intermediate energies

    Directory of Open Access Journals (Sweden)

    Shyam Radhey

    2016-01-01

    Full Text Available In the domain of Nuclear reactions at intermediate energies, the QCD coupling constant αs is large enough (~ 0.3 - 0.5 to render the perturbative calculational techniques inapplicable. In this regime the quarks are confined into colorless hadrons and it is expected that effective field theories of hadron interactions via exchange of hadrons, provide useful tools to describe such reactions. In this contribution we discuss the application of one such theory, the effective Lagrangian model, in describing the hadronic reactions at intermediate energies whose measurements are the focus of a vast international experimental program.

  7. [Arthropod bite reactions and pyodermias].

    Science.gov (United States)

    Hengge, U R

    2008-08-01

    Tourists in the tropics often develop reactions to bites or stings of mosquitoes, fleas, mites, ants, bedbugs, beetles, larva, millipedes, spiders and scorpions. In addition, they may have fresh or salt water exposure to sponges, corals, jellyfish and sea urchins with resultant injury and inflammation. Bacterial skin infections (pyodermias) can follow bites or stings as well as mechanical trauma. The most common bacteria involved in skin infections are staphylococci and streptococci. For tourists, bacterial infections are often complicating a pruritic bite reaction and scratching. It is important to know the cause of the bite reaction and pyoderma in order to take appropriate therapeutic measures.

  8. On the Reaction Path Hamiltonian

    Institute of Scientific and Technical Information of China (English)

    孙家钟; 李泽生

    1994-01-01

    A vector-fiber bundle structure of the reaction path Hamiltonian, which has been introduced by Miller, Handy and Adams, is explored with respect to molecular vibrations orthogonal to the reaction path. The symmetry of the fiber bundle is characterized by the real orthogonal group O(3N- 7) for the dynamical system with N atoms. Under the action of group O(3N- 7). the kinetic energy of the reaction path Hamiltonian is left invariant. Furthermore , the invariant behaviour of the Hamiltonian vector fields is investigated.

  9. Palladium-catalyzed coupling reactions

    CERN Document Server

    Molnár, Árpád

    2013-01-01

    This handbook and ready reference brings together all significant issues of practical importance for interested readers in one single volume. While covering homogeneous and heterogeneous catalysis, the text is unique in focusing on such important aspects as using different reaction media, microwave techniques or catalyst recycling. It also provides a comprehensive treatment of modern-day coupling reactions and emphasizes those topics that show potential for future development, such as continuous flow systems, water as a reaction medium, and catalyst immobilization, among others. With i

  10. Chemical potential and reaction electronic flux in symmetry controlled reactions.

    Science.gov (United States)

    Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

    2016-07-15

    In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc.

  11. Search for η-mesic 4He in the dd →3He nπ0 and dd →3He pπ- reactions with the WASA-at-COSY facility

    Science.gov (United States)

    Adlarson, P.; Augustyniak, W.; Bardan, W.; Bashkanov, M.; Bergmann, F. S.; Berłowski, M.; Bhatt, H.; Bondar, A.; Büscher, M.; Calén, H.; Ciepał, I.; Clement, H.; Czerwiński, E.; Demmich, K.; Engels, R.; Erven, A.; Erven, W.; Eyrich, W.; Fedorets, P.; Föhl, K.; Fransson, K.; Goldenbaum, F.; Goswami, A.; Grigoryev, K.; Gullström, C.-O.; Heijkenskjöld, L.; Hejny, V.; Hüsken, N.; Jarczyk, L.; Johansson, T.; Kamys, B.; Kelkar, N. G.; Kemmerling, G.; Khatri, G.; Khoukaz, A.; Khreptak, O.; Kirillov, D. A.; Kistryn, S.; Kleines, H.; Kłos, B.; Krzemień, W.; Kulessa, P.; Kupść, A.; Kuzmin, A.; Lalwani, K.; Lersch, D.; Lorentz, B.; Magiera, A.; Maier, R.; Marciniewski, P.; Mariański, B.; Morsch, H.-P.; Moskal, P.; Ohm, H.; Perez del Rio, E.; Piskunov, N. M.; Prasuhn, D.; Pszczel, D.; Pysz, K.; Pyszniak, A.; Ritman, J.; Roy, A.; Rudy, Z.; Rundel, O.; Sawant, S.; Schadmand, S.; Schätti-Ozerianska, I.; Sefzick, T.; Serdyuk, V.; Shwartz, B.; Sitterberg, K.; Skorodko, T.; Skurzok, M.; Smyrski, J.; Sopov, V.; Stassen, R.; Stepaniak, J.; Stephan, E.; Sterzenbach, G.; Stockhorst, H.; Ströher, H.; Szczurek, A.; Trzciński, A.; Varma, R.; Wolke, M.; Wrońska, A.; Wüstner, P.; Yamamoto, A.; Zabierowski, J.; Zieliński, M. J.; Złomańczuk, J.; Żuprański, P.; Żurek, M.

    2017-03-01

    The search for 4He- η bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd →3He nπ0 and dd →3He pπ- processes. The deuteron beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the dd →4He η reaction ranging from Q = - 70 MeV to Q = 30 MeV. The luminosity was determined based on the dd →3He n reaction and the quasi-free proton-proton scattering via dd → ppnspectatornspectator reactions. The excitation functions, determined independently for the measured reactions, do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in dd →(4He- η) bound →3He nπ0 and dd →(4He- η) bound →3He pπ- processes were determined taking into account the isospin relation between the both of the considered channels. The results of the analysis depend on the assumptions of the N*(1535) momentum distribution in the anticipated mesic-4He. Assuming, as in the previous works, that this is identical with the distribution of nucleons bound with 20 MeV in 4He, we determined that (for the mesic bound state width in the range from 5 MeV to 50 MeV) the upper limits at 90% confidence level are about 3 nb and about 6 nb for nπ0 and pπ- channels, respectively. However, based on the recent theoretical findings of the N*(1535) momentum distribution in the N*-3He nucleus bound by 3.6 MeV, we find that the WASA-at-COSY detector acceptance decreases and hence the corresponding upper limits are 5 nb and 10 nb for nπ0 and pπ- channels respectively.

  12. Reactions with light exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Lichtenthäler, R.; Faria, P.N. de; Pires, K.C.C.; Lepine-Szily, A.; Guimaraes, V.; Mendes Junior, D.R.; Assuncao, M.; Barioni, A.; Morcelle, V.; Morais, M.C.; Camargo Junior, O.; Alcantara Nuñez, J. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica; Moro, A.M. [Departamento de FAMN, Universidad de Sevilla, Sevilla (Spain); Arazi, A. [Laboratorio Tandar, Departamento de Fisica, Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Rodriguez-Gallardo, M. [Instituto de Estructura de la Materia, CSIC, Madrid (Spain)

    2014-07-01

    Experimental cross sections for the {sup 6}He+{sup 120}Sn are analysed. Elastic scattering angular distributions and alpha particle production cross sections have been measured and are compared with the total reaction cross sections. (author)

  13. Legendre Analysis of Hadronic Reactions

    CERN Document Server

    Azimov, Ya I

    2016-01-01

    Expansions over Legendre functions are suggested as a model-independent way of compact presentation of modern precise and high-statistics data for two-hadron reactions. Some properties of the expansions are described.

  14. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    Vivek V Ranade

    2014-03-01

    Catalytic reactions are ubiquitous in chemical and allied industries. A homogeneous or heterogeneous catalyst which provides an alternative route of reaction with lower activation energy and better control on selectivity can make substantial impact on process viability and economics. Extensive studies have been conducted to establish sound basis for design and engineering of reactors for practising such catalytic reactions and for realizing improvements in reactor performance. In this article, application of recent (and not so recent) developments in engineering reactors for catalytic reactions is discussed. Some examples where performance enhancement was realized by catalyst design, appropriate choice of reactor, better injection and dispersion strategies and recent advances in process intensification/ multifunctional reactors are discussed to illustrate the approach.

  15. The Paterno-Buchi reaction

    DEFF Research Database (Denmark)

    Brogaard, Rasmus Yding; Schalk, Oliver; Boguslavskiy, Andrey E.

    2012-01-01

    The Paternò-Büchi (PB) reaction between an excited carbonyl compound and an alkene has been widely studied, but so far little is known about the excited-state dynamics of the reaction. In this investigation, we used a compound in which a formyl and a vinyl group are attached to a [2.2]paracycloph......The Paternò-Büchi (PB) reaction between an excited carbonyl compound and an alkene has been widely studied, but so far little is known about the excited-state dynamics of the reaction. In this investigation, we used a compound in which a formyl and a vinyl group are attached to a [2...

  16. Analysis of kinetic reaction mechanisms

    CERN Document Server

    Turányi, Tamás

    2014-01-01

    Chemical processes in many fields of science and technology, including combustion, atmospheric chemistry, environmental modelling, process engineering, and systems biology, can be described by detailed reaction mechanisms consisting of numerous reaction steps. This book describes methods for the analysis of reaction mechanisms that are applicable in all these fields. Topics addressed include: how sensitivity and uncertainty analyses allow the calculation of the overall uncertainty of simulation results and the identification of the most important input parameters, the ways in which mechanisms can be reduced without losing important kinetic and dynamic detail, and the application of reduced models for more accurate engineering optimizations. This monograph is invaluable for researchers and engineers dealing with detailed reaction mechanisms, but is also useful for graduate students of related courses in chemistry, mechanical engineering, energy and environmental science and biology.

  17. Reactions with light exotic nuclei

    Directory of Open Access Journals (Sweden)

    Lichtenthäler R.

    2014-04-01

    Full Text Available Experimental cross sections for the 6He+120Sn are analysed. Elastic scattering angular distributions and alpha particle production cross sections have been measured and are compared with the total reaction cross sections.

  18. Color Changes Mark Polymer Reactions.

    Science.gov (United States)

    Krieger, James H.

    1980-01-01

    Describes how polydiacetylenes can be used as educational aids. These polymers have conjugated backbones, which cause changes in color when the polydiacetylenes undergo various chemical and physical processes. Diagrams summarize all chemical reactions and their associated color changes. (CS)

  19. Thermodynamics of random reaction networks.

    Directory of Open Access Journals (Sweden)

    Jakob Fischer

    Full Text Available Reaction networks are useful for analyzing reaction systems occurring in chemistry, systems biology, or Earth system science. Despite the importance of thermodynamic disequilibrium for many of those systems, the general thermodynamic properties of reaction networks are poorly understood. To circumvent the problem of sparse thermodynamic data, we generate artificial reaction networks and investigate their non-equilibrium steady state for various boundary fluxes. We generate linear and nonlinear networks using four different complex network models (Erdős-Rényi, Barabási-Albert, Watts-Strogatz, Pan-Sinha and compare their topological properties with real reaction networks. For similar boundary conditions the steady state flow through the linear networks is about one order of magnitude higher than the flow through comparable nonlinear networks. In all networks, the flow decreases with the distance between the inflow and outflow boundary species, with Watts-Strogatz networks showing a significantly smaller slope compared to the three other network types. The distribution of entropy production of the individual reactions inside the network follows a power law in the intermediate region with an exponent of circa -1.5 for linear and -1.66 for nonlinear networks. An elevated entropy production rate is found in reactions associated with weakly connected species. This effect is stronger in nonlinear networks than in the linear ones. Increasing the flow through the nonlinear networks also increases the number of cycles and leads to a narrower distribution of chemical potentials. We conclude that the relation between distribution of dissipation, network topology and strength of disequilibrium is nontrivial and can be studied systematically by artificial reaction networks.

  20. Reaction screening using a microreactor.

    Science.gov (United States)

    Naef, Olivier; Roch, Mathieu; Chappuis, Thierry

    2010-01-01

    This article discusses the screening of chemical reactions using a microreactor equipped with infrared spectroscopy as online analytics. An esterification reaction has been optimized in continuous mode with the proposed setup. The esterification did not work well due to the material of the microreactor (stainless-steel 316Ti) that catalyzed the decomposition of formic acid. However, despite the occurrence of decomposition, an optimization could be achieved with this system.

  1. Small Satellite Reaction Wheel Optimization

    OpenAIRE

    Michaelis, Ted

    1990-01-01

    The very "smallness" of small satellites mandates mass minimization. This paper addresses minimization of overall reaction wheel mass, including the incremental mass of the power subsystem needed to support the reaction wheel. The results are applicable to a wide range of wheel sizes and are suitable for optimization at the configuration level. For an average momentum and torque operating point, the minimization process yields wheel radius and angular velocity, as well as, the masses associat...

  2. Urticarial Reaction Caused by Ethanol

    Directory of Open Access Journals (Sweden)

    Yukinobu Nakagawa

    2006-01-01

    Discussion: Only acetic acid, a metabolite of alcohol, induced a positive prick test in the patient with alcohol-induced urticaria. This result was not observed in normal volunteers. An oral challenge test with diluted-alcohol or Shochu showed a positive wheal reaction in a dose dependent-manner which suggests that urticaria seen in this patient might be induced by alcohol-intolerance. However possible allergic reaction to acetaldehyde could not be excluded.

  3. Reciprocity theory of homogeneous reactions

    Science.gov (United States)

    Agbormbai, Adolf A.

    1990-03-01

    The reciprocity formalism is applied to the homogeneous gaseous reactions in which the structure of the participating molecules changes upon collision with one another, resulting in a change in the composition of the gas. The approach is applied to various classes of dissociation, recombination, rearrangement, ionizing, and photochemical reactions. It is shown that for the principle of reciprocity to be satisfied it is necessary that all chemical reactions exist in complementary pairs which consist of the forward and backward reactions. The backward reaction may be described by either the reverse or inverse process. The forward and backward processes must satisfy the same reciprocity equation. Because the number of dynamical variables is usually unbalanced on both sides of a chemical equation, it is necessary that this balance be established by including as many of the dynamical variables as needed before the reciprocity equation can be formulated. Statistical transformation models of the reactions are formulated. The models are classified under the titles free exchange, restricted exchange and simplified restricted exchange. The special equations for the forward and backward processes are obtained. The models are consistent with the H theorem and Le Chatelier's principle. The models are also formulated in the context of the direct simulation Monte Carlo method.

  4. A Calibration Reaction For NIF

    Science.gov (United States)

    Vande Kolk, B.; Chen, Y.; Deboer, R. J.; Gilardy, G.; Liu, Q.; Lyons, S.; Manukyan, K.; Moran, M.; Seymour, C.; Stech, E.; Strauss, S.; Wiescher, M.

    2016-09-01

    The National Ignition Facility (NIF) can produce a temperature range imitating that which occurs in a star during its hydrogen burning phase. The 10B(p, α)7Be reaction has been selected as a way to determine the temperatures created at NIF. The advantage of this calibration reaction is the product: Be-7 has a half-life of 53.2 days, sufficient for gathering and studying the abundance created while also decaying within several months. A 10 keV resonance exists which dominates the 10B(p, α)7Be reaction as well as 10B(p, γ)11C, another reaction channel of 10B+p. Additionally, another resonance exists for both reactions at 600 keV. There is not reliable extrapolation to the low energies corresponding to those of NIF due to the two mentioned resonances interfering, with a shared spin-parity 5/2+. Measurements were performed and will be presented for the cross-sections of the 10B(p, α)7Be and 10B(p, γ)11C reactions to more confidently extrapolate to lower energies. Research supported by NSF PHY-1419765 and JINA-CEE PHY-1430152.

  5. Late reaction, persistent reaction and doubtful allergic reaction: The problems of interpretation

    Directory of Open Access Journals (Sweden)

    Sarma Nilendu

    2009-01-01

    Full Text Available The standard method of patch test reading is to read the test site for any positive allergy at 48hr and then again at 72/96 hr. A late reading on the seventh day is also advised to exclude the irritant reaction (IR and to notice some delayed development of allergic reaction. However, multiple visits are often difficult for the patient; therefore, this late reading is sometimes omitted. Here a case of plantar hyperkeratosis, due to allergic contact dermatitis, is reported with some insight into interpretation of the patch test. The patient showed delayed patch test reaction to formaldehyde and colophony, which has never been reported before.

  6. Reaction rates for mesoscopic reaction-diffusion kinetics.

    Science.gov (United States)

    Hellander, Stefan; Hellander, Andreas; Petzold, Linda

    2015-02-01

    The mesoscopic reaction-diffusion master equation (RDME) is a popular modeling framework frequently applied to stochastic reaction-diffusion kinetics in systems biology. The RDME is derived from assumptions about the underlying physical properties of the system, and it may produce unphysical results for models where those assumptions fail. In that case, other more comprehensive models are better suited, such as hard-sphere Brownian dynamics (BD). Although the RDME is a model in its own right, and not inferred from any specific microscale model, it proves useful to attempt to approximate a microscale model by a specific choice of mesoscopic reaction rates. In this paper we derive mesoscopic scale-dependent reaction rates by matching certain statistics of the RDME solution to statistics of the solution of a widely used microscopic BD model: the Smoluchowski model with a Robin boundary condition at the reaction radius of two molecules. We also establish fundamental limits on the range of mesh resolutions for which this approach yields accurate results and show both theoretically and in numerical examples that as we approach the lower fundamental limit, the mesoscopic dynamics approach the microscopic dynamics. We show that for mesh sizes below the fundamental lower limit, results are less accurate. Thus, the lower limit determines the mesh size for which we obtain the most accurate results.

  7. Reaction rates for a generalized reaction-diffusion master equation.

    Science.gov (United States)

    Hellander, Stefan; Petzold, Linda

    2016-01-01

    It has been established that there is an inherent limit to the accuracy of the reaction-diffusion master equation. Specifically, there exists a fundamental lower bound on the mesh size, below which the accuracy deteriorates as the mesh is refined further. In this paper we extend the standard reaction-diffusion master equation to allow molecules occupying neighboring voxels to react, in contrast to the traditional approach, in which molecules react only when occupying the same voxel. We derive reaction rates, in two dimensions as well as three dimensions, to obtain an optimal match to the more fine-grained Smoluchowski model and show in two numerical examples that the extended algorithm is accurate for a wide range of mesh sizes, allowing us to simulate systems that are intractable with the standard reaction-diffusion master equation. In addition, we show that for mesh sizes above the fundamental lower limit of the standard algorithm, the generalized algorithm reduces to the standard algorithm. We derive a lower limit for the generalized algorithm which, in both two dimensions and three dimensions, is of the order of the reaction radius of a reacting pair of molecules.

  8. Concordant chemical reaction networks and the Species-Reaction Graph.

    Science.gov (United States)

    Shinar, Guy; Feinberg, Martin

    2013-01-01

    In a recent paper it was shown that, for chemical reaction networks possessing a subtle structural property called concordance, dynamical behavior of a very circumscribed (and largely stable) kind is enforced, so long as the kinetics lies within the very broad and natural weakly monotonic class. In particular, multiple equilibria are precluded, as are degenerate positive equilibria. Moreover, under certain circumstances, also related to concordance, all real eigenvalues associated with a positive equilibrium are negative. Although concordance of a reaction network can be decided by readily available computational means, we show here that, when a nondegenerate network's Species-Reaction Graph satisfies certain mild conditions, concordance and its dynamical consequences are ensured. These conditions are weaker than earlier ones invoked to establish kinetic system injectivity, which, in turn, is just one ramification of network concordance. Because the Species-Reaction Graph resembles pathway depictions often drawn by biochemists, results here expand the possibility of inferring significant dynamical information directly from standard biochemical reaction diagrams.

  9. Reaction rates for a generalized reaction-diffusion master equation

    Science.gov (United States)

    Hellander, Stefan; Petzold, Linda

    2016-01-01

    It has been established that there is an inherent limit to the accuracy of the reaction-diffusion master equation. Specifically, there exists a fundamental lower bound on the mesh size, below which the accuracy deteriorates as the mesh is refined further. In this paper we extend the standard reaction-diffusion master equation to allow molecules occupying neighboring voxels to react, in contrast to the traditional approach, in which molecules react only when occupying the same voxel. We derive reaction rates, in two dimensions as well as three dimensions, to obtain an optimal match to the more fine-grained Smoluchowski model and show in two numerical examples that the extended algorithm is accurate for a wide range of mesh sizes, allowing us to simulate systems that are intractable with the standard reaction-diffusion master equation. In addition, we show that for mesh sizes above the fundamental lower limit of the standard algorithm, the generalized algorithm reduces to the standard algorithm. We derive a lower limit for the generalized algorithm which, in both two dimensions and three dimensions, is of the order of the reaction radius of a reacting pair of molecules.

  10. Reaction rates for mesoscopic reaction-diffusion kinetics

    Science.gov (United States)

    Hellander, Stefan; Hellander, Andreas; Petzold, Linda

    2015-02-01

    The mesoscopic reaction-diffusion master equation (RDME) is a popular modeling framework frequently applied to stochastic reaction-diffusion kinetics in systems biology. The RDME is derived from assumptions about the underlying physical properties of the system, and it may produce unphysical results for models where those assumptions fail. In that case, other more comprehensive models are better suited, such as hard-sphere Brownian dynamics (BD). Although the RDME is a model in its own right, and not inferred from any specific microscale model, it proves useful to attempt to approximate a microscale model by a specific choice of mesoscopic reaction rates. In this paper we derive mesoscopic scale-dependent reaction rates by matching certain statistics of the RDME solution to statistics of the solution of a widely used microscopic BD model: the Smoluchowski model with a Robin boundary condition at the reaction radius of two molecules. We also establish fundamental limits on the range of mesh resolutions for which this approach yields accurate results and show both theoretically and in numerical examples that as we approach the lower fundamental limit, the mesoscopic dynamics approach the microscopic dynamics. We show that for mesh sizes below the fundamental lower limit, results are less accurate. Thus, the lower limit determines the mesh size for which we obtain the most accurate results.

  11. Nuclear Reactions for Astrophysics and Other Applications

    Energy Technology Data Exchange (ETDEWEB)

    Escher, J E; Burke, J T; Dietrich, F S; Scielzo, N D; Ressler, J J

    2011-03-01

    Cross sections for compound-nuclear reactions are required for many applications. The surrogate nuclear reactions method provides an indirect approach for determining cross sections for reactions on unstable isotopes, which are difficult or impossible to measure otherwise. Current implementations of the method provide useful cross sections for (n,f) reactions, but need to be improved upon for applications to capture reactions.

  12. A comprehensive survey of nuclear reactions; Panorama des reactions nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Cugnon, J. [Liege Univ., IFPA, AGO Dept. (Belgium)

    2007-07-01

    The various mechanisms of nuclear reactions are surveyed and classified in different regimes, based on the notions of coherent mechanisms and hard versus soft processes. The emphasis is put on the concepts at the basis of the understanding of these regimes and on the elements of nuclear structure which are involved in these different regimes, as well as the on the possibility of extracting this information. Due to lack of space and for pedagogical reasons, the discussion is limited to nucleon-induced and light-ion-induced reactions. However, a few remarks are given concerning some specific probes, such as weakly bound projectiles or neutron-rich nuclei. (author)

  13. Carbonitriding reactions of diatomaceous earth: phase evolution and reaction mechanisms

    Directory of Open Access Journals (Sweden)

    BRANKO MATOVIC

    2006-06-01

    Full Text Available The possibility of using diatomaceous earth as Si precursor for low temperature synthesis of non-oxide powders by carbothermal reduction-nitridation was studied. It was found that carbonitriding reactions produce phases of the Si–Al–O–N system. Already at 1300 °C, nanosized, non-oxide powders were obtained. The comparatively low reaction temperatures is attributred to the nano-porous nature of the raw material. The evolution of crystalline phases proceeded via many intermediate stages. The powders were characterized by X-ray and SEM investigations. The results showed that diatomaceous earth can be a very effective source for obtaining non-oxide powders.

  14. Acute anaphylactic reaction to expired chlorpheniramine injection

    Institute of Scientific and Technical Information of China (English)

    Beuy Joob; Viroj Wiwanitkit

    2014-01-01

    Chlorpheniramine is a widely used drug for management of allergic reaction.The serious adverse reaction to this drug is extremely rare.In this report, the authors present a case of acute anaphylactic reaction to expired chlorpheniramine injection.

  15. Acute anaphylactic reaction to expired chlorpheniramine injection

    Directory of Open Access Journals (Sweden)

    Beuy Joob

    2014-01-01

    Full Text Available Chlorpheniramine is a widely used drug for management of allergic reaction. The serious adverse reaction to this drug is extremely rare. In this report, the authors present a case of acute anaphylactic reaction to expired chlorpheniramine injection.

  16. Reaction of Nitrosonium (NO+) with Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    Yu Lu ZHOU; Cong De HUO; Shu MIAO; Long Min WU

    2004-01-01

    The reaction of nitrosonium (NO+) with Schiff bases produced diazonium salts and aldehydes in good yield. The reaction is assumed to be an electrophilic reaction of nitrosonium with imines via a four-member ring intermediate.

  17. Enzymatic Reactions in Microfluidic Devices

    Science.gov (United States)

    Ristenpart, W. D.; Wan, J.; Stone, H. A.

    2008-11-01

    We establish simple scaling laws for enzymatic reactions in microfluidic devices, and we demonstrate that kinetic parameters obtained conventionally using multiple stop-flow experiments may instead be extracted from a single microfluidic experiment. Introduction of an enzyme and substrate species in different arms of a Y-shaped channel allows the two species to diffuse across the parallel streamlines and to begin reacting. Measurements of the product concentration versus distance down the channel provide information about the kinetics of the reaction. In the limit where the enzyme is much larger (and thus less diffusive) than the substrate, we show that near the entrance the total amount of product (P) formed varies as a power law in the distance x down the channel. For reactions that follow standard Michaelis-Menten kinetics, the power law takes the form P˜(Vmax/Km) x^5/2, where Vmax and Km are the maximum reaction rate and Michaelis constant respectively. If a large excess of substrate is used, then Km is identified by measuring Vmax far downstream where the different species are completely mixed by diffusion. Numerical simulations and experiments using the bioluminescent reaction between luciferase and ATP as a model system are both shown to accord with the model. We discuss the implications for significant savings in the amount of time and enzyme required for determination of kinetic parameters.

  18. Quantifying mixing using equilibrium reactions

    Science.gov (United States)

    Wheat, Philip M.; Posner, Jonathan D.

    2009-03-01

    A method of quantifying equilibrium reactions in a microchannel using a fluorometric reaction of Fluo-4 and Ca2+ ions is presented. Under the proper conditions, equilibrium reactions can be used to quantify fluid mixing without the challenges associated with constituent mixing measures such as limited imaging spatial resolution and viewing angle coupled with three-dimensional structure. Quantitative measurements of CaCl and calcium-indicating fluorescent dye Fluo-4 mixing are measured in Y-shaped microchannels. Reactant and product concentration distributions are modeled using Green's function solutions and a numerical solution to the advection-diffusion equation. Equilibrium reactions provide for an unambiguous, quantitative measure of mixing when the reactant concentrations are greater than 100 times their dissociation constant and the diffusivities are equal. At lower concentrations and for dissimilar diffusivities, the area averaged fluorescence signal reaches a maximum before the species have interdiffused, suggesting that reactant concentrations and diffusivities must be carefully selected to provide unambiguous, quantitative mixing measures. Fluorometric equilibrium reactions work over a wide range of pH and background concentrations such that they can be used for a wide variety of fluid mixing measures including industrial or microscale flows.

  19. Combustion kinetics and reaction pathways

    Energy Technology Data Exchange (ETDEWEB)

    Klemm, R.B.; Sutherland, J.W. [Brookhaven National Laboratory, Upton, NY (United States)

    1993-12-01

    This project is focused on the fundamental chemistry of combustion. The overall objectives are to determine rate constants for elementary reactions and to elucidate the pathways of multichannel reactions. A multitechnique approach that features three independent experiments provides unique capabilities in performing reliable kinetic measurements over an exceptionally wide range in temperature, 300 to 2500 K. Recent kinetic work has focused on experimental studies and theoretical calculations of the methane dissociation system (CH{sub 4} + Ar {yields} CH{sub 3} + H + Ar and H + CH{sub 4} {yields} CH{sub 3} + H{sub 2}). Additionally, a discharge flow-photoionization mass spectrometer (DF-PIMS) experiment is used to determine branching fractions for multichannel reactions and to measure ionization thresholds of free radicals. Thus, these photoionization experiments generate data that are relevant to both reaction pathways studies (reaction dynamics) and fundamental thermochemical research. Two distinct advantages of performing PIMS with high intensity, tunable vacuum ultraviolet light at the National Synchrotron Light Source are high detection sensitivity and exceptional selectivity in monitoring radical species.

  20. [Mechanisms of cutaneous drug reactions].

    Science.gov (United States)

    Vaillant, L

    2000-06-15

    Two main mechanisms, pharmacologic and immunoallergic, are responsible for cutaneous reactions to drugs. Pharmacologic mechanisms can be predictable (overdosage, cumulative or delayed toxicity, adverse effects) or unpredictable (idiosyncratic, intolerance, or anaphylactic reaction). Immunoallergic mechanisms can be mediated by IgE (some types of urticaria and anaphylactic shock), due to circulating immune complexes (leukocytoclastic vasculitis, serum sickness-type reactions) or mediated by lymphocytes (exanthema, Lyell's syndrome, fixed pigmented erythema, photosensitization). The diagnostic work-up varies according to the causative mechanism. When the reaction is predictable, the responsible drug can be identified according to the data in the present bibliography. When the reaction is immunologic, only the chronologic sequence of events can identify the responsible drug. The risk of recurrence with an identical or related molecule also varies according to the causative mechanism. For urticaria, diagnosis and the risk of recurrence differ according to whether the cause is allergic (mediated by IgE or urticarial vasculitis) or is pharmacologic (urticaria due to aspirin or to conversion enzyme inhibitors).

  1. Thermal reactions of brushite cements.

    Science.gov (United States)

    Bohner, M; Gbureck, U

    2008-02-01

    The thermal reactions of a brushite cement made of beta-tricalcium phosphate (beta-TCP), monocalcium phosphate monohydrate (MCPM), and an aqueous solution were followed in situ with an isothermal calorimeter at 37 degrees C. The investigated parameters were the beta-TCP/MCPM weight ratio, the liquid-to-powder ratio, the synthesis route and milling duration of the beta-TCP powder, as well as the presence of sulfate, citrate, and pyrophosphate ions in the mixing liquid. The thermograms were complex, particularly for mixtures containing an excess of MCPM or additives in the mixing solution. Results suggested that the endothermic MCPM dissolution and the highly exothermic beta-TCP dissolution occurred simultaneously, thereby leading to the formation of a large exothermic peak at early reaction time. Both reactions were followed by the exothermic crystallization of brushite and in the presence of an excess of MCPM by the endothermic crystallization of monetite. Additives generally widened the main exothermic reaction peak, or in some cases with pyrophosphate ions postponed the main exothermic peak at late reaction time. Generally, the results could be well explained and understood based on thermodynamic and solubility data.

  2. Mechanisms of severe transfusion reactions.

    Science.gov (United States)

    Kopko, P M; Holland, P V

    2001-06-01

    Serious adverse effects of transfusion may be immunologically or non-immunologically mediated. Currently, bacterial contamination of blood products, particularly platelets, is one of the most significant causes of transfusion-related morbidity and mortality. Septic transfusion reactions can present with clinical symptoms similar to immune-mediated hemolytic transfusion reactions and transfusion-related acute lung injury. Extremely high fever and/or gastrointestinal symptoms, in a transfusion recipient, may be indicative of sepsis. The diagnosis is based upon culturing the same organism from both the patient and the transfused blood component. Numerous organisms have been implicated as the cause of septic transfusion reactions. Due to different storage conditions, gram negative organisms are more often isolated from red blood cell components; gram positive organisms are more often isolated from platelets. Prevention of septic transfusion reactions is primarily dependent on an adequate donor history and meticulous preparation of the donor phlebotomy site. Visual inspection of blood components prior to transfusion is also vital to preventing these reactions. Several methods of detection of bacterial contamination and inactivation of pathogens are currently under active investigation.

  3. Electrocardiographic changes in lepra reaction.

    Science.gov (United States)

    Zawar, P B; Chawhan, R N; Swami, R M

    1983-04-01

    The electrocardiographic (E.C.G.) changes were evaluated in 54 patients of lepra reaction. Abnormalities of the E.C.G. observed were in the form of prolongation of QTc in 24 (44.44%), ST-T changes in a (16.66%), bundle branch block and ventricular extrasystoles in 2 each (3.70%). The mean QTc interval in 64 normal adults was 0.41 second (S.D. +/- 0.03, range 0.36 to 0.44 second). It was 0.44 second (S.D. +/- 0.05, range 0.38 to 0.52 second) in patients of lepra reaction. The difference in the QTc values in the two groups was statistically significant (P less than 0.01). The E.C.G. abnormalities in patients of lepra reaction appears to be due to myocardial involvement.

  4. Photonuclear reactions on titanium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Belyshev, S. S. [Moscow State University (Russian Federation); Dzhilavyan, L. Z. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation); Ishkhanov, B. S.; Kapitonov, I. M. [Moscow State University (Russian Federation); Kuznetsov, A. A., E-mail: kuznets@depni.sinp.msu.ru; Orlin, V. N.; Stopani, K. A. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

    2015-03-15

    The photodisintegration of titanium isotopes in the giant-dipole-resonance energy region is studied by the photon-activation method. Bremsstrahlung photons whose spectrum has the endpoint energy of 55 MeV is used. The yields and integrated cross sections are determined for photoproton reactions on the titanium isotopes {sup 47,48,49,50}Ti. The respective experimental results are compared with their counterparts calculated on the basis of the TALYS code and a combined photonucleon-reaction model. The TALYS code disregards the isospin structure of the giant dipole resonance and is therefore unable to describe the yield of photoproton reactions on the heavy titanium isotopes {sup 49,50}Ti.

  5. Radiation reaction in various dimensions

    CERN Document Server

    Galtsov, D V

    2002-01-01

    We discuss the radiation reaction problem for an electric charge moving in flat space-time of arbitrary dimensions. It is shown that four is the unique dimension where a local differential equation exists accounting for the radiation reaction and admitting a consistent mass-renormalization (the Dirac-Lorentz equation). In odd dimensions the Huygens principle does not hold; as a result, the radiation reaction force depends on the whole past history of a charge (radiative tail). We show that the divergence in the tail integral can be removed by the mass renormalization only in the 2+1 theory. In even dimensions higher than four, divergences can not be removed by a renormalization.

  6. Radiation reaction in various dimensions

    Science.gov (United States)

    Gal'Tsov, Dmitri V.

    2002-07-01

    We discuss the radiation reaction problem for an electric charge moving in flat space-time of arbitrary dimensions. It is shown that four is the unique dimension where a local differential equation exists accounting for the radiation reaction and admitting a consistent mass renormalization (the Lorentz-Dirac equation). In odd dimensions Huygens's principle does not hold, and, as a result, the radiation reaction force depends on the whole past history of a charge (radiative tail). We show that the divergence in the tail integral can be removed by the mass renormalization only in the 2+1 theory. In even dimensions higher than four, divergences cannot be removed by the mass renormalization.

  7. Back Reaction of Cosmological Perturbations

    CERN Document Server

    Brandenberger, R H

    2000-01-01

    The presence of cosmological perturbations affects the background metric and matter configuration in which the perturbations propagate. This effect, studied a long time ago for gravitational waves, also is operational for scalar gravitational fluctuations, inhomogeneities which are believed to be more important in inflationary cosmology. The back-reaction of fluctuations can be described by an effective energy-momentum tensor. The issue of coordinate invariance makes the analysis more complicated for scalar fluctuations than for gravitational waves. We show that the back-reaction of fluctuations can be described in a diffeomorphism-invariant way. In an inflationary cosmology, the back-reaction is dominated by infrared modes. We show that these modes give a contribution to the effective energy-momentum tensor of the form of a negative cosmological constant whose absolute value grows in time. We speculate that this may lead to a self-regulating dynamical relaxation mechanism for the cosmological constant. This ...

  8. Light in elementary biological reactions

    Science.gov (United States)

    Sundström, Villy

    2000-09-01

    Light plays an important role in biology. In this review we discuss several processes and systems where light triggers a biological response, i.e. photosynthesis, vision, photoreceptors. For these functions Nature has chosen simple elementary chemical reactions, which occur in highly specialized and organized structures. The high efficiency and specificity of these reactions make them interesting for applications in light energy conversion and opto-electronics. In order to emphasize the synergism in studies of natural and synthetic systems we will discuss a few of each kind, with similar functions. In all cases light triggers a rapid sequence of events, which makes ultrafast spectroscopy an ideal tool to disentangle reaction mechanisms and dynamics.

  9. A unified diabatic description for electron transfer reactions, isomerization reactions, proton transfer reactions, and aromaticity.

    Science.gov (United States)

    Reimers, Jeffrey R; McKemmish, Laura K; McKenzie, Ross H; Hush, Noel S

    2015-10-14

    While diabatic approaches are ubiquitous for the understanding of electron-transfer reactions and have been mooted as being of general relevance, alternate applications have not been able to unify the same wide range of observed spectroscopic and kinetic properties. The cause of this is identified as the fundamentally different orbital configurations involved: charge-transfer phenomena involve typically either 1 or 3 electrons in two orbitals whereas most reactions are typically closed shell. As a result, two vibrationally coupled electronic states depict charge-transfer scenarios whereas three coupled states arise for closed-shell reactions of non-degenerate molecules and seven states for the reactions implicated in the aromaticity of benzene. Previous diabatic treatments of closed-shell processes have considered only two arbitrarily chosen states as being critical, mapping these states to those for electron transfer. We show that such effective two-state diabatic models are feasible but involve renormalized electronic coupling and vibrational coupling parameters, with this renormalization being property dependent. With this caveat, diabatic models are shown to provide excellent descriptions of the spectroscopy and kinetics of the ammonia inversion reaction, proton transfer in N2H7(+), and aromaticity in benzene. This allows for the development of a single simple theory that can semi-quantitatively describe all of these chemical phenomena, as well as of course electron-transfer reactions. It forms a basis for understanding many technologically relevant aspects of chemical reactions, condensed-matter physics, chemical quantum entanglement, nanotechnology, and natural or artificial solar energy capture and conversion.

  10. Inorganic Reaction Mechanisms Part II: Homogeneous Catalysis

    Science.gov (United States)

    Cooke, D. O.

    1976-01-01

    Suggests several mechanisms for catalysis by metal ion complexes. Discusses the principal factors of importance in these catalysis reactions and suggests reactions suitable for laboratory study. (MLH)

  11. Microscopic effective reaction theory for direct nuclear reactions

    Directory of Open Access Journals (Sweden)

    Ogata Kazuyuki

    2016-01-01

    Full Text Available Some recent activities with the microscopic effective reaction theory (MERT on elastic, inelastic, breakup, transfer, and knockout processes are reviewed briefly. As a possible alternative to MERT, a description of elastic and inelastic scattering with the continuum particle-vibration coupling (cPVC method is also discussed.

  12. Miniaturized continuous flow reaction vessels: influence on chemical reactions

    NARCIS (Netherlands)

    Brivio, M.; Verboom, Willem; Reinhoudt, David

    2006-01-01

    This review offers an overview of the relatively young research area of continuous flow lab-on-a-chip for synthetic applications. A short introduction on the basic aspects of lab-on-a-chip is given in the first part. Subsequently, the effects of downscaling reaction vessels as well as the advantages

  13. Vision 2020. Reaction Engineering Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Klipstein, David H. [Reaction Design, San Diego, CA (United States); Robinson, Sharon [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2001-01-01

    The Reaction Engineering Roadmap is a part of an industry- wide effort to create a blueprint of the research and technology milestones that are necessary to achieve longterm industry goals. This report documents the results of a workshop focused on the research needs, technology barriers, and priorities of the chemical industry as they relate to reaction engineering viewed first by industrial use (basic chemicals; specialty chemicals; pharmaceuticals; and polymers) and then by technology segment (reactor system selection, design, and scale-up; chemical mechanism development and property estimation; dealing with catalysis; and new, nonstandard reactor types).

  14. A photoinduced, benzyne click reaction.

    Science.gov (United States)

    Gann, Adam W; Amoroso, Jon W; Einck, Vincent J; Rice, Walter P; Chambers, James J; Schnarr, Nathan A

    2014-04-04

    The [3 + 2] cycloaddition of azides and alkynes has proven invaluable across numerous scientific disciplines for imaging, cross-linking, and site-specific labeling among many other applications. We have developed a photoinitiated, benzyne-based [3 + 2] cycloaddition that is tolerant of a variety of functional groups as well as polar, protic solvents. The reaction is complete on the minute time scale using a single equivalent of partner azide, and the benzyne photoprecursor is stable for months under ambient light at room tempurature. Herein we report the optimization and scope of the photoinitiated reaction as well as characterization of the cycloaddition products.

  15. Learning to predict chemical reactions.

    Science.gov (United States)

    Kayala, Matthew A; Azencott, Chloé-Agathe; Chen, Jonathan H; Baldi, Pierre

    2011-09-26

    Being able to predict the course of arbitrary chemical reactions is essential to the theory and applications of organic chemistry. Approaches to the reaction prediction problems can be organized around three poles corresponding to: (1) physical laws; (2) rule-based expert systems; and (3) inductive machine learning. Previous approaches at these poles, respectively, are not high throughput, are not generalizable or scalable, and lack sufficient data and structure to be implemented. We propose a new approach to reaction prediction utilizing elements from each pole. Using a physically inspired conceptualization, we describe single mechanistic reactions as interactions between coarse approximations of molecular orbitals (MOs) and use topological and physicochemical attributes as descriptors. Using an existing rule-based system (Reaction Explorer), we derive a restricted chemistry data set consisting of 1630 full multistep reactions with 2358 distinct starting materials and intermediates, associated with 2989 productive mechanistic steps and 6.14 million unproductive mechanistic steps. And from machine learning, we pose identifying productive mechanistic steps as a statistical ranking, information retrieval problem: given a set of reactants and a description of conditions, learn a ranking model over potential filled-to-unfilled MO interactions such that the top-ranked mechanistic steps yield the major products. The machine learning implementation follows a two-stage approach, in which we first train atom level reactivity filters to prune 94.00% of nonproductive reactions with a 0.01% error rate. Then, we train an ensemble of ranking models on pairs of interacting MOs to learn a relative productivity function over mechanistic steps in a given system. Without the use of explicit transformation patterns, the ensemble perfectly ranks the productive mechanism at the top 89.05% of the time, rising to 99.86% of the time when the top four are considered. Furthermore, the system

  16. Fundamentals of chemical reaction engineering

    CERN Document Server

    Davis, Mark E

    2012-01-01

    Appropriate for a one-semester undergraduate or first-year graduate course, this text introduces the quantitative treatment of chemical reaction engineering. It covers both homogeneous and heterogeneous reacting systems and examines chemical reaction engineering as well as chemical reactor engineering. The authors take a chemical approach, helping students develop an intuitive feeling for concepts, rather than an engineering approach, which tends to overlook the inner workings of systems and objects.Each chapter contains numerous worked-out problems and real-world vignettes involving commercia

  17. Incomplete reactions in nanothermite composites

    Science.gov (United States)

    Jacob, Rohit J.; Ortiz-Montalvo, Diana L.; Overdeep, Kyle R.; Weihs, Timothy P.; Zachariah, Michael R.

    2017-02-01

    Exothermic reactions between oxophilic metals and transition/post transition metal-oxides have been well documented owing to their fast reaction time scales (≈10 μs). This article examines the extent of the reaction in nano-aluminum based thermite systems through a forensic inspection of the products formed during reaction. Three nanothermite systems (Al/CuO, Al/Bi2O3, and Al/WO3) were selected owing to their diverse combustion characteristics, thereby providing sufficient generality and breadth to the analysis. Microgram quantities of the sample were coated onto a fine platinum wire, which was resistively heated at high heating rates (≈105 K/s) to ignite the sample. The subsequent products were captured/quenched very rapidly (≈500 μs) in order to preserve the chemistry/morphology during initiation and subsequent reaction and were quantitatively analyzed using electron microscopy and focused ion beam cross-sectioning followed by energy dispersive X-ray spectroscopy. Elemental examination of the cross-section of the quenched particles shows that oxygen is predominantly localized in the regions containing aluminum, implying the occurrence of the redox reaction. The Al/CuO system, which has simultaneous gaseous oxygen release and ignition (TIgnition ≈ TOxygen Release), shows a substantially lower oxygen content within the product particles as opposed to Al/Bi2O3 and Al/WO3 thermites, which are postulated to undergo a condensed phase reaction (TIgnition ≪ TOxygen Release). An effective Al:O composition for the interior section was obtained for all the mixtures, with the smaller particles generally showing a higher oxygen content than the larger ones. The observed results were further corroborated with the reaction temperature, obtained using a high-speed spectro-pyrometer, and bomb calorimetry conducted on larger samples (≈15 mg). The results suggest that thermites that produce sufficient amounts of gaseous products generate smaller product particles and

  18. Reactions

    DEFF Research Database (Denmark)

    Søndergaard, Morten

    2011-01-01

      My concern is to understand augmentation as an emergent modality - among many others in ‘the expanding digital field' (Søndergaard M. , Transformative Creativity in the Expanded Digital Field, 2009)' - attributed to the production of contemporary art and the ‘archive of knowledge' in the (art......) museum. Augmentation, in this expanding digital field, is part of a production of new public spaces, as well as a new reality that affects and traverses art and institutions immanently and througout. The expanding digital field is transforming art and the art museum in a number of fundamental ways, a few...... that ties together ... (Robert J.K. Jacob, 2008) I suggest that a negotiation between reality-based interaction and a digital dialectic (Lunenfeld, 1999)(Søndergaard M. o., 2008) is becoming still more evident, on two levels: 1) As an investigation into (the visuality of) a digital reality under...

  19. Reaction to a Campus Confrontation

    Science.gov (United States)

    Epstein, Yakov M.; And Others

    1971-01-01

    Students' reactions to the occupation of a university building were surveyed on the first and last day of the occupation as well as several weeks following the end of the occupation. Results of the survey show that the conflict tended to polarize attitudes about radicals against them and increase attitudes favorable to conventional political…

  20. Palladium-Catalysed Coupling Reactions

    NARCIS (Netherlands)

    de Vries, Johannes G.; Beller, M; Blaser, HU

    2012-01-01

    Palladium-catalysed coupling reactions have gained importance as a tool for the production of pharmaceutical intermediates and to a lesser extent also for the production of agrochemicals, flavours and fragrances, and monomers for polymers. In this review only these cases are discussed where it seems

  1. INTERFACE REACTION IN MAGNETIC MULTILAYERS

    Institute of Scientific and Technical Information of China (English)

    G.H. Yu; M.H. Li; F.W. Zhu; X.F. Cui; J.L. Jin

    2001-01-01

    Ta/NiO/NiFe/Ta multilayers were prepared by rf reactive and dc magnetron sputter-ing. The exchange coupling field (Hex) between NiO and NiFe reached 120Oe. Thecomposition and chemical states at the interface region of NiO/NiFe were studied us-ing the x-ray photoelectron spectroscopy (XPS) and peak decomposition technique. Theresults show that there are two thermodynamically favorable reactions at NiO/NiFeinterface: NiO+Fe = Ni+FeO and 3NiO+2Fe 3Ni+Fe2 O3. The thickness of thechemical reaction as estimated by angle-resolved XPS was about 1-1.5nm. These in-terrace reaction products are magnetic defects, and we believe that the Hex and thecoereivity (He) of NiO/NiFe ave affected by these defects. Moreover, the results alsoshow that there is an "intermixing layer" at the Ta/NiO (and NiO/Ta) interface dueto a thermodynamically favorable reaction: 2Ta+5NiO=5Ni+Ta2O5. This interfacereaction has an effect on the exchange coupling as well. The thickness of the "inter-mixing layer" as estimated by XPS depth-profiles was about 8-10nm.

  2. Electrochemical reactions of organosilicon compounds

    Science.gov (United States)

    Jouikov, Vyacheslav V.

    1997-06-01

    Data on the processes of electrochemical reduction and oxidation of organosilicon compounds of various classes as well as on the interaction of these compounds with electrically generated reagents are generalised and surveyed systematically. The electrochemical reactivity of organic derivatives of silicon is considered taking into account their structures and reaction conditions. The bibliography includes 245 references.

  3. Teachers' Reactions to Children's Aggression

    Science.gov (United States)

    Nesdale, Drew; Pickering, Kaye

    2006-01-01

    Drawing on social schema theory (Fiske & Taylor, 1991) and social identity theory (Tajfel & Turner, 1979), this study examined the impact on teachers' reactions to children's aggression of three variables, two of which were related to the aggressors and one was related to the teachers. Experienced female elementary school teachers (N=90) each read…

  4. Humanism and science: a reaction.

    Science.gov (United States)

    Wampold, Bruce E

    2012-12-01

    Authors in this section have noted that humanism is intrinsic to psychotherapy, although disagreements remain. One of the disagreements is about the role of science in humanism. In this reaction, I contend that humanism, as discussed in these articles, is a legitimate theory to be subjected to scientific scrutiny. (c) 2012 APA, all rights reserved.

  5. Reduction of chemical reaction models

    Science.gov (United States)

    Frenklach, Michael

    1991-01-01

    An attempt is made to reconcile the different terminologies pertaining to reduction of chemical reaction models. The approaches considered include global modeling, response modeling, detailed reduction, chemical lumping, and statistical lumping. The advantages and drawbacks of each of these methods are pointed out.

  6. Severe immediate reaction to nabumetone.

    Science.gov (United States)

    Gonzalo-Garijo, M A; Cordobés-Duran, C; Lamilla-Yerga, A M; Moreno-Gastón, I

    2007-01-01

    Nabumetone is a nonsteroidal antiinflammatory (NSAID) prodrug that inhibits cyclooxygenase-2. It has been recommended as a safe alternative in most patients with hypersensitivity reactions to NSAIDs. Systemic reactions caused by nabumetone are not frequent. We report 2 cases of immediate systemic reactions due to nabumetone. The first case involved a 68-year-old woman who developed immediate generalized pruritus, erythema, morbilliform eruption, swollen tongue sensation, diarrhea, and hypotension after the ingestion of a single dose of nabumetone. In the second case, a 77-year-old woman developed generalized pruritus, palm erythema, colic abdominal pain, diarrhea, dizziness, tightness of the chest, dyspnea, and hypotension immediately after oral intake of nabumetone. Both patients had previously tolerated this drug. Since these episodes, they have avoided nabumetone. Skin prick tests with nabumetone (10 and 100 mg/mL) were negative. Oral challenge tests with other NSAIDs, even of the same group as nabumetone, were negative in both patients. The mechanisms responsible for the reaction were not established.

  7. Anaphylactic reactions to tolperisone (Mydocalm).

    Science.gov (United States)

    Ribi, Camillo; Vermeulen, Christophe; Hauser, Conrad

    2003-06-28

    Four patients with anaphylaxis attributed to the intake of the centrally acting muscle relaxant tolperisone hydrochloride (Mydocalm) were observed at the Emergency Department of the Geneva University Hospital between November 2001 and March 2003. All patients were middle-aged women who took tolperisone for chronic muscular pain. All reactions occurred within an hour after oral intake of this drug frequently prescribed in Switzerland. The severity of anaphylaxis ranged from urticarial reactions to shock with arterial hypotension. Prick-to-prick skin testing performed in one patient with a tablet of tolperisone diluted in water was negative. Its globally restricted commercialisation may explain the lack of reports on such adverse effects in the MedLine database. Anaphylactic reactions to this drug, however, are mentioned in other sources such as the Swiss Drug Compendium and the WHO drug reaction database. Together, these findings suggest that anaphylaxis to tolperisone is not uncommon and should be known to physicians in countries where this drug is available.

  8. The Pitfalls of Precipitation Reactions.

    Science.gov (United States)

    Slade, Peter W.; Rayner-Canham, Geoffrey W.

    1990-01-01

    Described are some of the difficulties presented in these reactions by competing equilibria that are usually ignored. Situations involving acid-base equilibria, solubility product calculations, the use of ammonia as a complexing agent, and semiquantitative comparisons of solubility product values are discussed. (CW)

  9. Surface science of heterogeneous reactions.

    Science.gov (United States)

    White, J M

    1982-10-29

    Some of the present and future directions for surface science as a growing and naturally interdisciplinary subject are reviewed. Particular attention is given to surface reaction chemistry as it is related to heterogenous catalysis, a subject area where there are abundant opportunities for detailed measurements of structure and dynamics at the molecular level.

  10. Reactions of ethanol on Ru

    NARCIS (Netherlands)

    Sturm, Jacobus Marinus; Liu, Feng; Lee, Christopher James; Bijkerk, Frederik

    2012-01-01

    The adsorption and reactions of ethanol on Ru(0001) were studied with temperatureprogrammed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS). Ethanol was found to adsorb intact onto Ru(0001) below 100 K. Heating to 250 K resulted in formation of ethoxy groups, which undergo

  11. Reactions of arsine with hemoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Hatlelid, K.M.; Brailsford, C.; Carter, D.E. [Univ. of Arizona, Tucson, AZ (United States)

    1996-02-09

    The mechanism of arsine (AsH{sub 3}) induced hemolysis was studied in vitro using isolated red blood cells (RBCs) from the rat or dog. AsH{sub 3}-induced hemolysis of dog red blood cells was completely blocked by carbon monoxide (CO) preincubation and was reduced by pure oxygen (O{sub 2}) compared to incubations in air. Since CO and O{sub 2} bind to heme and also reduced hemolysis, these results suggested a reaction between AsH{sub 3} and hemoglobin in the hemeligand binding pocket or with the heme iron. Further, sodium nitrite induction of methemoglobin (metHb) to 85% and 34% of total Hb in otherwise intact RBCs resulted in 56% and 16% decreases in hemolysis, respectively, after incubation for 4 h. This provided additional evidence for the involvement of hemoglobin in the AsH{sub 3}-induced hemolysis mechanism. Reactions between AsH{sub 3} and hemoglobin were studied in solutions of purified dog hemoglobin. Spectrophotometric studies of the reaction of AsH{sub 3} with various purified hemoglobin species revealed that AsH{sub 3} reacted with HbO{sub 2} to produce metHb and, eventually, degraded Hb characterized by gross precipitation of the protein. AsH{sub 3} did not alter the spectrum of deoxyHb and did not cause degradation of metHb in oxygen, but bound to and reduced metHb in the absence of oxygen. These data indicate that a reaction of AsH{sub 3} with oxygenated hemoglobin, HbO{sub 2}, may lead to hemolysis, but there are reactions between AsH{sub 3} and metHb that may not be directly involved in the hemolytic process. 17 refs., 6 figs.

  12. Nucleosynthesis by photon-induced reactions

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, P. E-mail: mohr@ikpAu-darmstadt.de; Babilon, M.; Galaviz, D.; Sonnabend, K.; Vogt, K.; Zilges, A

    2003-05-19

    Similar to the well-known Gamow window for charged particle induced reactions, there exists an effective energy window for photon-induced reactions. Properties of this window are discussed in detail for ({gamma}, n) and ({gamma}, {alpha}) reactions. These reactions are important for the nucleosynthesis of rare neutron-deficient p nuclei.

  13. Experimental Demonstrations in Teaching Chemical Reactions.

    Science.gov (United States)

    Hugerat, Muhamad; Basheer, Sobhi

    2001-01-01

    Presents demonstrations of chemical reactions by employing different features of various compounds that can be altered after a chemical change occurs. Experimental activities include para- and dia-magnetism in chemical reactions, aluminum reaction with base, reaction of acid with carbonates, use of electrochemical cells for demonstrating chemical…

  14. Thermodynamics of Enzyme-Catalyzed Reactions Database

    Science.gov (United States)

    SRD 74 Thermodynamics of Enzyme-Catalyzed Reactions Database (Web, free access)   The Thermodynamics of Enzyme-Catalyzed Reactions Database contains thermodynamic data on enzyme-catalyzed reactions that have been recently published in the Journal of Physical and Chemical Reference Data (JPCRD). For each reaction the following information is provided: the reference for the data, the reaction studied, the name of the enzyme used and its Enzyme Commission number, the method of measurement, the data and an evaluation thereof.

  15. Electrochemical promotion of catalytic reactions

    Science.gov (United States)

    Imbihl, R.

    2010-05-01

    The electrochemical promotion of heterogeneously catalyzed reactions (EPOC) became feasible through the use of porous metal electrodes interfaced to a solid electrolyte. With the O 2- conducting yttrium stabilized zirconia (YSZ), the Na + conducting β″-Al 2O 3 (β-alumina), and several other types of solid electrolytes the EPOC effect has been demonstrated for about 100 reaction systems in studies conducted mainly in the mbar range. Surface science investigations showed that the physical basis for the EPOC effect lies in the electrochemically induced spillover of oxygen and alkali metal, respectively, onto the surface of the metal electrodes. For the catalytic promotion effect general concepts and mechanistic schemes were proposed but these concepts and schemes are largely speculative. Applying surface analytical tools to EPOC systems the proposed mechanistic schemes can be verified or invalidated. This report summarizes the progress which has been achieved in the mechanistic understanding of the EPOC effect.

  16. Investigating Reaction-Driven Cracking

    Science.gov (United States)

    Kelemen, P. B.; Hirth, G.; Savage, H. M.

    2013-12-01

    Many metamorphic reactions lead to large volume changes, and potentially to reaction-driven cracking [1,2]. Large-scale hydration of mantle peridotite to produce serpentine or talc is invoked to explain the rheology of plate boundaries, the nature of earthquakes, and the seismic properties of slow-spread ocean crust and the 'mantle wedge' above subduction zones. Carbonation of peridotite may be an important sink in the global carbon cycle. Zones of 100% magnesite + quartz replacing peridotite, up to 200 m thick, formed where oceanic mantle was thrust over carbonate-bearing metasediments in Oman. Talc + carbonate is an important component of the matrix in subduction mélanges at Santa Catalina Island , California, and the Sanbagawa metamorphic belt, Japan. Engineered systems to emulate natural mineral carbonation could provide relatively inexpensive CO2 capture and storage [3]. More generally, engineered reaction-driven cracking could supplement or replace hydraulic fracture in geothermal systems, solution mining, and extraction of tight oil and gas. The controls on reaction-driven cracking are poorly understood. Hydration and carbonation reactions can be self-limiting, since they potentially reduce permeability and armor reactive surfaces [4]. Also, in some cases, hydration or carbonation may take place at constant volume. Small changes in volume due to precipitation of solid products increases stress, destabilizing solid reactants, until precipitation and dissolution rates become equal at a steady state stress [5]. In a third case, volume change due to precipitation of solid products causes brittle failure. This has been invoked on qualitative grounds to explain, e.g., complete serpentinization of mantle peridotite [6]. Below ~ 300°C, the available potential energy for hydration and carbonation of olivine could produce stresses of 100's of MPa [2], sufficient to fracture rocks to 10 km depth or more, causing brittle failure below the steady state stress required

  17. Nuclear Reactions from Lattice QCD

    CERN Document Server

    Briceño, Raúl A; Luu, Thomas C

    2014-01-01

    One of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low- energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path ...

  18. Synchrotron radiation with radiation reaction

    Science.gov (United States)

    Nelson, Robert W.; Wasserman, Ira

    1991-04-01

    A rigorous discussion is presented of the classical motion of a relativistic electron in a magnetic field and the resulting electromagnetic radiation when radiation reaction is important. In particular, for an electron injected with initial energy gamma(0), a systematic perturbative solution to the Lorentz-Dirac equation of motion is developed for field strengths satisfying gamma(0) B much less than 6 x 10 to the 15th G. A particularly accurate solution to the electron orbital motion in this regime is found and it is demonstrated how lowest-order corrections can be calculated. It is shown that the total energy-loss rate corresponds to what would be found using the exact Larmor power formula without including radiation reaction. Provided that the particle energy and field strength satisfy the same contraint, it is explicitly demonstrated that the intuitive prescription for calculating the time-integrated radiation spectrum described above is correct.

  19. Late reaction to ustekinumab infusion

    Directory of Open Access Journals (Sweden)

    Marina Resener Morais

    2013-09-01

    Full Text Available Psoriasis is a chronic inflammatory disease that directly affects the quality of life. Biologics are prescribed for patients unresponsive to conventional treatments and with severe forms of the disease. Ustekinumab is a fully human monoclonal antibody against the p40 subunit of interleukins 12/23 that is being used with satisfactory responses, achieving an improvement in the baseline Psoriasis Area and Severity Index of approximately 75% after 12 weeks of treatment. It has few side effects, including grater susceptibility to infections and development of reactions to the drug. Our report discusses a case of a cutaneous reaction to the use of ustekinumab in a 27 year-old male patient after the third dose of the medication. No similar case has been reported in the literature.

  20. Radiation Reaction on Brownian Motions

    CERN Document Server

    Seto, Keita

    2016-01-01

    Tracking the real trajectory of a quantum particle is one of the interpretation problem and it is expressed by the Brownian (stochastic) motion suggested by E. Nelson. Especially the dynamics of a radiating electron, namely, radiation reaction which requires us to track its trajectory becomes important in the high-intensity physics by PW-class lasers at present. It has been normally treated by the Furry picture in non-linear QED, but it is difficult to draw the real trajectory of a quantum particle. For the improvement of this, I propose the representation of a stochastic particle interacting with fields and show the way to describe radiation reaction on its Brownian motion.

  1. Nuclear reaction studies: Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Thaler, R.M.

    1986-11-19

    A principal focus of recent research has been the three-body problem. A great deal of effort has been devoted to the creation of a computer program to calculate physical observables in the three body problem below 1 GeV. Successful results have been obtained for the triton. Additional work concerns scattering of K/sup +/ mesons from nuclei, antinucleon physics, relativistic nuclear physics and inclusive reactions. (DWL)

  2. Reactions to threatening health messages

    Directory of Open Access Journals (Sweden)

    ten Hoor Gill A

    2012-11-01

    Full Text Available Abstract Background Threatening health messages that focus on severity are popular, but frequently have no effect or even a counterproductive effect on behavior change. This paradox (i.e. wide application despite low effectiveness may be partly explained by the intuitive appeal of threatening communication: it may be hard to predict the defensive reactions occurring in response to fear appeals. We examine this hypothesis by using two studies by Brown and colleagues, which provide evidence that threatening health messages in the form of distressing imagery in anti-smoking and anti-alcohol campaigns cause defensive reactions. Methods We simulated both Brown et al. experiments, asking participants to estimate the reactions of the original study subjects to the threatening health information (n = 93. Afterwards, we presented the actual original study outcomes. One week later, we assessed whether this knowledge of the actual study outcomes helped participants to more successfully estimate the effectiveness of the threatening health information (n = 72. Results Results showed that participants were initially convinced of the effectiveness of threatening health messages and were unable to anticipate the defensive reactions that in fact occurred. Furthermore, these estimates did not improve after participants had been explained the dynamics of threatening communication as well as what the effects of the threatening communication had been in reality. Conclusions These findings are consistent with the hypothesis that the effectiveness of threatening health messages is intuitively appealing. What is more, providing empirical evidence against the use of threatening health messages has very little effect on this intuitive appeal.

  3. Statistical theory of breakup reactions

    Energy Technology Data Exchange (ETDEWEB)

    Bertulani, Carlos A., E-mail: carlos.bertulani@tamuc.edu [Department of Physics and Astronomy, Texas A and M University-Commerce, Commerce, TX (United States); Descouvemont, Pierre, E-mail: pdesc@ulb.ac.be [Physique Nucleaire Theorique et Physique Mathematique, Universite Libre de Bruxelles (ULB), Brussels (Belgium); Hussein, Mahir S., E-mail: hussein@if.usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Estudos Avancados

    2014-07-01

    We propose an alternative for Coupled-Channels calculations with loosely bound exotic nuclei (CDCC), based on the the Random Matrix Model of the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCC{sub s}), able in principle to take into account many pseudo channels. (author)

  4. Statistical Theory of Breakup Reactions

    Directory of Open Access Journals (Sweden)

    Bertulani Carlos A.

    2014-04-01

    Full Text Available We propose an alternative for Coupled-Channels calculations with looselybound exotic nuclei(CDCC, based on the the Random Matrix Model of the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCCs, able in principle to take into account many pseudo channels.

  5. Strangeness exchange reactions and hypernuclei

    Energy Technology Data Exchange (ETDEWEB)

    Dover, C.B.

    1982-01-01

    Recent progress in the spectroscopy of ..lambda.. and ..sigma.. hypernuclei is reviewed. Prospects for the production of doubly strange hypernuclei at a future kaon factory are assessed. It is suggested that the (K/sup -/,K/sup +/) reaction on a nuclear target may afford an optimal way of producing the H dibaryon, a stable six quark object with J/sup ..pi../ = O/sup +/, S = -2.

  6. Statistical Theory of Breakup Reactions

    CERN Document Server

    Bertulani, Carlos A; Hussein, Mahir S

    2014-01-01

    We propose alternatives to coupled-channels calculations with loosely-bound exotic nuclei (CDCC), based on the the random matrix (RMT) and the optical background (OPM) models for the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCC$_S$), able in principle to take into account many pseudo channels.

  7. Statistical Theory of Breakup Reactions

    Science.gov (United States)

    Bertulani, Carlos A.; Descouvemont, Pierre; Hussein, Mahir S.

    2014-04-01

    We propose an alternative for Coupled-Channels calculations with looselybound exotic nuclei(CDCC), based on the the Random Matrix Model of the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCCs), able in principle to take into account many pseudo channels.

  8. Anaphylactic reaction to intravenous diclofenac

    Directory of Open Access Journals (Sweden)

    Ranju Singh

    2011-01-01

    Full Text Available Diclofenac sodium is a non-steroidal anti-inflammatory drug widely used as an opioid sparing agent for postoperative analgesia. Anaphylaxis due to intravenous diclofenac sodium is very rare. We report a case of anaphylactic reaction to IV diclofenac sodium, occurring postoperatively in a 25-year-old primigravida, the clinical features of which mimicked pulmonary embolism. The rarity, clinical importance and the diagnostic dilemma associated prompted us to report this case.

  9. Gold-catalyzed domino reactions.

    Science.gov (United States)

    Michelet, Véronique

    2015-01-01

    Gold-catalyzed reactions have appeared to be highly attractive tools for chemists to promote novel transformations to prepare elaborated structures from simple starting materials. This chapter presents selected and original examples of domino processes in the presence of gold catalysts, highlighting reports implying hydration, hydroxylation, and hydroamination as key starting point for cascade transformations. Domino processes implying 1,n-enynes, asymmetric domino transformations, and applications of all the presented processes in total synthesis are presented.

  10. Apparent tunneling in chemical reactions

    DEFF Research Database (Denmark)

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

    2000-01-01

    A necessary condition for tunneling in a chemical reaction is that the probability of crossing a barrier is non-zero, when the energy of the reactants is below the potential energy of the barrier. Due to the non-classical nature (i.e, momentum uncertainty) of vibrational states this is, however, ...... to the high momentum tail of the initial vibrational state of nitrogen, allowing for amplitude to cross over the barrier. (C) 2000 Elsevier Science B.V. All rights reserved....

  11. Force approach to radiation reaction

    Energy Technology Data Exchange (ETDEWEB)

    López, Gustavo V., E-mail: gulopez@udgserv.cencar.udg.mx

    2016-02-15

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  12. Force approach to radiation reaction

    Science.gov (United States)

    López, Gustavo V.

    2016-02-01

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  13. Reaction Selectivity in Heterogeneous Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, Gabor A.; Kliewer, Christopher J.

    2009-02-02

    The understanding of selectivity in heterogeneous catalysis is of paramount importance to our society today. In this review we outline the current state of the art in research on selectivity in heterogeneous catalysis. Current in-situ surface science techniques have revealed several important features of catalytic selectivity. Sum frequency generation vibrational spectroscopy has shown us the importance of understanding the reaction intermediates and mechanism of a heterogeneous reaction, and can readily yield information as to the effect of temperature, pressure, catalyst geometry, surface promoters, and catalyst composition on the reaction mechanism. DFT calculations are quickly approaching the ability to assist in the interpretation of observed surface spectra, thereby making surface spectroscopy an even more powerful tool. HP-STM has revealed three vitally important parameters in heterogeneous selectivity: adsorbate mobility, catalyst mobility, and selective site-blocking. The development of size controlled nanoparticles from 0.8 to 10 nm, of controlled shape, and of controlled bimetallic composition has revealed several important variables for catalytic selectivity. Lastly, DFT calculations may be paving the way to guiding the composition choice for multi-metallic heterogeneous catalysis for the intelligent design of catalysts incorporating the many factors of selectivity we have learned.

  14. CHLORINATION OF AMINO ACIDS: REACTION PATHWAYS AND REACTION RATES.

    Science.gov (United States)

    How, Zuo Tong; Linge, Kathryn; Busetti, Francesco; Joll, Cynthia A

    2017-03-15

    Chlorination of amino acids can result in the formation of organic monochloramines or organic dichloramines, depending on the chlorine to amino acid ratio (Cl:AA). After formation, organic chloramines degrade into aldehydes, nitriles and N-chloraldimines. In this paper, the formation of organic chloramines from chlorination of lysine, tyrosine and valine were investigated. Chlorination of tyrosine and lysine demonstrated that the presence of a reactive secondary group can increase the Cl:AA ratio required for the formation of N,N-dichloramines, and potentially alter the reaction pathways between chlorine and amino acids, resulting in the formation of unexpected by-products. In a detailed investigation, we report rate constants for all reactions in the chlorination of valine, for the first time, using experimental results and modelling. At Cl:AA = 2.8, the chlorine was found to first react quickly with valine (5.4x104 M-1 s-1) to form N-monochlorovaline, with a slower subsequent reaction with N-monochlorovaline to form N,N-dichlorovaline (4.9x102 M-1 s-1), although some N-monochlorovaline degraded into isobutyraldehyde (1.0x10-4 s-1). The N,N-dichlorovaline then competitively degraded into isobutyronitrile (1.3x10-4 s-1) and N-chloroisobutyraldimine (1.2x10-4 s-1). In conventional drinking water disinfection, N-chloroisobutyraldimine can potentially be formed in concentrations higher than its odour threshold concentration, resulting in aesthetic challenges and an unknown health risk.

  15. Modelling Chemical Reasoning to Predict Reactions

    CERN Document Server

    Segler, Marwin H S

    2016-01-01

    The ability to reason beyond established knowledge allows Organic Chemists to solve synthetic problems and to invent novel transformations. Here, we propose a model which mimics chemical reasoning and formalises reaction prediction as finding missing links in a knowledge graph. We have constructed a knowledge graph containing 14.4 million molecules and 8.2 million binary reactions, which represents the bulk of all chemical reactions ever published in the scientific literature. Our model outperforms a rule-based expert system in the reaction prediction task for 180,000 randomly selected binary reactions. We show that our data-driven model generalises even beyond known reaction types, and is thus capable of effectively (re-) discovering novel transformations (even including transition-metal catalysed reactions). Our model enables computers to infer hypotheses about reactivity and reactions by only considering the intrinsic local structure of the graph, and because each single reaction prediction is typically ac...

  16. Reaction Kinetics of Nanostructured Silicon Carbide

    Science.gov (United States)

    Wallis, Kendra; Zerda, T. W.

    2006-10-01

    Nanostructured silicon carbide (SiC) is of interest particularly for use in nanocomposites that demonstrate high hardness as well as for use in semiconductor applications. Reaction kinetics studies of solid-solid reactions are relatively recent and present a method of determining the reaction mechanism and activation energy by measuring reaction rates. We have used induction heating to heat quickly, thus reducing the error in reaction time measurements. Data will be presented for reactions using silicon nanopowder (melting point of silicon. Using the well-known Avrami-Erofeev model, a two-parameter chi- square fit of the data provided a rate constant (k) and parameter (n), related to the reaction mechanism, for each temperature. From these data, an activation energy of 138 kJ/mol was calculated. In addition, the parameter n suggests the reaction mechanism, which will also be discussed. Experiments are continuing at higher temperatures to consider the liquid- solid reaction as well.

  17. Reaction path synthesis methodology for waste minimization

    Institute of Scientific and Technical Information of China (English)

    HU; Shanying; LI; Mingheng; LI; Yourun; SHEN; Jingzhu; LIU

    2004-01-01

    It is a key step for reducing waste generation in chemical processes to design optimal reaction paths. In this paper, methods of waste minimization for reaction path synthesis problems are proposed to realize eco-industrial production mode with minimum waste emission. A new conception of simple stoichiometric reaction is presented for reaction path synthesis problem. All simple stoichiometric reactions can be obtained by mathematical transformation for atom matrix of a reaction system. Based on the conception, a two-tier optimization method for complex reaction path synthesis problems is addressed. The first step is to determine the economic optimal overall reactions, and the second step to decompose each overall reaction into several sub-reactions and find out the best thermodynamic feasible reaction path. Further, a method of reaction path synthesis with waste closed-cycle is proposed based on simple stoichiometric reactions for achieving zero waste emission to poly-generation problem of multi-products. Case studies show that the proposed methods can efficiently solve practical reaction path synthesis problems.

  18. The molecular dynamics of atmospheric reaction

    Science.gov (United States)

    Polanyi, J. C.

    1971-01-01

    Detailed information about the chemistry of the upper atmosphere took the form of quantitative data concerning the rate of reaction into specified states of product vibration, rotation and translation for exothermic reaction, as well as concerning the rate of reaction from specified states of reagent vibration, rotation and translation for endothermic reaction. The techniques used were variants on the infrared chemiluminescence method. Emphasis was placed on reactions that formed, and that removed, vibrationally-excited hydroxyl radicals. Fundamental studies were also performed on exothermic reactions involving hydrogen halides.

  19. Chemical reactions in solvents and melts

    CERN Document Server

    Charlot, G

    1969-01-01

    Chemical Reactions in Solvents and Melts discusses the use of organic and inorganic compounds as well as of melts as solvents. This book examines the applications in organic and inorganic chemistry as well as in electrochemistry. Organized into two parts encompassing 15 chapters, this book begins with an overview of the general properties and the different types of reactions, including acid-base reactions, complex formation reactions, and oxidation-reduction reactions. This text then describes the properties of inert and active solvents. Other chapters consider the proton transfer reactions in

  20. Metal-catalyzed asymmetric aldol reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Luiz C.; Lucca Junior, Emilio C. de; Ferreira, Marco A. B.; Polo, Ellen C., E-mail: ldias@iqm.unicamp.br [Universidade de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica

    2012-12-15

    The aldol reaction is one of the most powerful and versatile methods for the construction of C-C bonds. Traditionally, this reaction was developed in a stoichiometric version; however, great efforts in the development of chiral catalysts for aldol reactions were performed in recent years. Thus, in this review article, the development of metal-mediated chiral catalysts in Mukaiyama-type aldol reaction, reductive aldol reaction and direct aldol reaction are discussed. Moreover, the application of these catalysts in the total synthesis of complex molecules is discussed. (author)

  1. Reaction cross-section predictions for nucleon induced reactions

    CERN Document Server

    Nobre, G P A; Escher, J E; Dietrich, F S

    2010-01-01

    A microscopic calculation of the optical potential for nucleon-nucleus scattering has been performed by explicitly coupling the elastic channel to all the particle-hole (p-h) excitation states in the target and to all relevant pickup channels. These p-h states may be regarded as doorway states through which the flux flows to more complicated configurations, and to long-lived compound nucleus resonances. We calculated the reaction cross sections for the nucleon induced reactions on the targets $^{40,48}$Ca, $^{58}$Ni, $^{90}$Zr and $^{144}$Sm using the QRPA description of target excitations, coupling to all inelastic open channels, and coupling to all transfer channels corresponding to the formation of a deuteron. The results of such calculations were compared to predictions of a well-established optical potential and with experimental data, reaching very good agreement. The inclusion of couplings to pickup channels were an important contribution to the absorption. For the first time, calculations of excitatio...

  2. Effect of Pozzolanic Reaction Products on Alkali-silica Reaction

    Institute of Scientific and Technical Information of China (English)

    WEI Fengyan; LAN Xianghui; LV Yinong; XU Zhongzi

    2006-01-01

    The effect of fly ash on controlling alkali-silica reaction (ASR) in simulated alkali solution was studied. The expansion of mortar bars and the content of Ca(OH)2 in cement paste cured at 80 ℃ for 91 d were measured. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) were employed to study the microstructure of C-S-H. TEM/energy dispersive spectroscopy (EDS) was then used to determine the composition of C-S-H. The pore structure of the paste was analyzed by mercury intrusion porosimetry (MIP). The results show that the contents of fly ash of 30% and 45% can well inhibit ASR. And the content of Ca(OH)2 decreases with the increase of fly ash. That fly ash reacted with Ca(OH)2 to produce C-S-H with a low Ca/Si molar ratio could bind more Na+ and K+ ions, and produce a reduction in the amount of soluble alkali available for ASR. At the same time, the C-S-H produced by pozzolanic reaction converted large pores to smaller ones (gel pores smaller than 10 nm) to densify the pore structure. Perhaps that could inhibit alkali transport to aggregate for ASR.

  3. Forgiveness, retaliation and paranoid reactions.

    Science.gov (United States)

    Hunter, R C

    1978-04-01

    It has been suggested that clinical states from grudgingness and habitual bitterness through to delusions of persecution are best resolved by forgiving. The process of forgiving requires that previously unacknowledged impulses, particularly aggressive ones, are accepted in oneself and others. If the therapist is aware of this, he can, in the transference, reinforce the patient's good introjects by providing a non-judgemental, acceptant model for the patient and thereby facilitate the adoption of the forgiving attitude. Sometimes habitual forgiving can occur as a reaction formation, and should be dealt with as such.

  4. Allergic reactions in red tattoos

    DEFF Research Database (Denmark)

    Hutton Carlsen, K; Køcks, M; Sepehri, M

    2016-01-01

    AIM: The aim of this study was to assess the feasibility of Raman spectroscopy as a screening technique for chemical characterisation of tattoo pigments in pathologic reacting tattoos and tattoo ink stock products to depict unsafe pigments and metabolites of pigments. MATERIALS/METHODS: Twelve...... to be feasible for chemical analysis of red pigments in allergic reactions. Raman spectroscopy has a major potential for fingerprint screening of problematic tattoo pigments in situ in skin, ex vivo in skin biopsies and in tattoo ink stock products, thus, to eliminate unsafe ink products from markets....

  5. Kinetics of heterogeneous catalytic reactions

    CERN Document Server

    Boudart, Michel

    2014-01-01

    This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase acc

  6. Chemical reactions at aqueous interfaces

    Science.gov (United States)

    Vecitis, Chad David

    2009-12-01

    Interfaces or phase boundaries are a unique chemical environment relative to individual gas, liquid, or solid phases. Interfacial reaction mechanisms and kinetics are often at variance with homogeneous chemistry due to mass transfer, molecular orientation, and catalytic effects. Aqueous interfaces are a common subject of environmental science and engineering research, and three environmentally relevant aqueous interfaces are investigated in this thesis: 1) fluorochemical sonochemistry (bubble-water), 2) aqueous aerosol ozonation (gas-water droplet), and 3) electrolytic hydrogen production and simultaneous organic oxidation (water-metal/semiconductor). Direct interfacial analysis under environmentally relevant conditions is difficult, since most surface-specific techniques require relatively `extreme' conditions. Thus, the experimental investigations here focus on the development of chemical reactors and analytical techniques for the completion of time/concentration-dependent measurements of reactants and their products. Kinetic modeling, estimations, and/or correlations were used to extract information on interfacially relevant processes. We found that interfacial chemistry was determined to be the rate-limiting step to a subsequent series of relatively fast homogeneous reactions, for example: 1) Pyrolytic cleavage of the ionic headgroup of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorbed to cavitating bubble-water interfaces during sonolysis was the rate-determining step in transformation to their inorganic constituents carbon monoxide, carbon dioxide, and fluoride; 2) ozone oxidation of aqueous iodide to hypoiodous acid at the aerosol-gas interface is the rate-determining step in the oxidation of bromide and chloride to dihalogens; 3) Electrolytic oxidation of anodic titanol surface groups is rate-limiting for the overall oxidation of organics by the dichloride radical. We also found chemistry unique to the interface, for example: 1

  7. Control Electronics For Reaction Wheel

    Science.gov (United States)

    Chamberlin, Keith

    1995-01-01

    Bidirectional operation achieved with single-polarity main power supply. Control circuitry generates pulse-width-modulated 800-Hz waveforms to drive two-phase ac motor and reaction wheel. Operates partly in response to digital magnitude-and-direction torque command generated by external control subsystem and partly in response to tachometric feedback in form of two once-per-revolution sinusoids with amplitudes proportional to speed. Operation in either of two modes called "normal" and "safehold." In normal mode, drive pulses timed so that, on average over one or few cycles, motor applies commanded torque. In safehold mode, pulses timed to keep motor running at set speed in one direction.

  8. Catalyst Initiation in the Oscillatory Carbonylation Reaction

    Directory of Open Access Journals (Sweden)

    Katarina Novakovic

    2011-01-01

    Full Text Available Palladium(II iodide is used as a catalyst in the phenylacetylene oxidative carbonylation reaction that has demonstrated oscillatory behaviour in both pH and heat of reaction. In an attempt to extract the reaction network responsible for the oscillatory nature of this reaction, the system was divided into smaller parts and they were studied. This paper focuses on understanding the reaction network responsible for the initial reactions of palladium(II iodide within this oscillatory reaction. The species researched include methanol, palladium(II iodide, potassium iodide, and carbon monoxide. Several chemical reactions were considered and applied in a modelling study. The study revealed the significant role played by traces of water contained in the standard HPLC grade methanol used.

  9. Effective radii of deuteron induced reactions

    CERN Document Server

    Hashimoto, Shintaro; Ogata, Kazuyuki; Minomo, Kosho; Chiba, Satoshi

    2011-01-01

    The continuum-discretized coupled-channels method (CDCC) for exclusive reactions and the eikonal reaction theory (ERT) as an extension of CDCC to inclusive reactions are applied to deuteron induced reactions. The CDCC result reproduces experimental data on the reaction cross section for $d+^{58}$Ni scattering at 200 MeV/nucleon and ERT does data on the neutron-stripping cross section for inclusive $^7$Li$(d,n)$ reaction at 40 MeV. For deuteron induced reactions at 200 MeV/nucleon, target-dependence of the reaction, elastic-breakup, nucleon-stripping, nucleon-removal, complete- and incomplete-fusion cross sections is clearly explained by simple formulae. Accuracy of the Glauber model is also investigated.

  10. Organic chemistry - Fast reactions 'on water'

    NARCIS (Netherlands)

    Klijn, JE; Engberts, JBFN

    2005-01-01

    Efficient reactions in aqueous organic chemistry do not require soluble reactants, as had been thought. A newly developed ‘on-water’ protocol is characterized by short reaction times, and the products are easy to isolate.

  11. The mechanism of the modified Ullmann reaction

    NARCIS (Netherlands)

    Sperotto, Elena; Klink, Gerard P.M. van; Koten, Gerard van; Vries, Johannes G. de

    2010-01-01

    The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) ma

  12. Reaction Wheel with Embedded MEMS IMU Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is to embed a MEMS IMU Sensor Chip into a reaction wheel to measure its spin rate as well as wheel attitude rate. We propose to use a reaction wheel...

  13. Recent Developments in Electron Transfer Reactions

    OpenAIRE

    Marcus, Rudolph A.

    1987-01-01

    Earlier results and more recent developments in electron transfer reactions are reviewed. The more recent results include inverted behavior, electronic orientation effects on reaction rates, solvent dynamics, early steps in photosynthesis, and light emission from metal electrodes.

  14. Heavy atom isotope effects on enzymatic reactions

    Science.gov (United States)

    Paneth, Piotr

    1994-05-01

    The theory of isotope effects, which has proved to be extremely useful in providing geometrical details of transition states in a variety of chemical reactions, has recently found an application in studies of enzyme-catalyzed reactions. These reactions are multistep in nature with few steps being partially rate-limiting, thus interpretation of these isotope effects is more complex. The theoretical framework of heavy-atom isotope effects on enzymatic reactions is critically analyzed on the basis of recent results of: carbon kinetic isotope effects on carbonic anhydrase and catalytic antibodies; multiple carbon, deuterium isotope effects on reactions catalyzed by formate decarboxylase; oxygen isotope effects on binding processes in reactions catalyzed by pyruvate kinase; and equilibrium oxygen isotope effect on binding an inhibitor to lactate dehydrogenase. The advantages and disadvantages of reaction complexity in learning details of formal and molecular mechanisms are discussed in the examples of reactions catalyzed by phosphoenolpyruvate carboxylase, orotidine decarboxylase and glutamine synthetase.

  15. Physical chemistry: The fingerprints of reaction mechanisms

    Science.gov (United States)

    Vallance, Claire

    2017-06-01

    Small changes to molecular structures can transform how reactions occur, but studying reaction mechanisms directly is difficult. An imaging technique that provides direct insights into competing mechanisms might improve matters.

  16. Common Parent Reactions to the NICU

    Science.gov (United States)

    ... Stages Listen Español Text Size Email Print Share Common Parent Reactions to the NICU Page Content Article ... their NICU stay. Anger Anger is also a common reaction to the initial NICU experience. Many parents ...

  17. Nuclear reactions from lattice QCD

    Science.gov (United States)

    Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.

    2015-02-01

    One of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, quantum chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three-nucleon (and higher) interactions in a consistent manner. Currently, lattice quantum chromodynamics (LQCD) provides the only reliable option for performing calculations of some of the low-energy hadronic observables. With the aim of bridging the gap between LQCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from LQCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.

  18. Hypersensitivity reactions associated with endovascular devices.

    Science.gov (United States)

    Honari, Golara; Ellis, Stephen G; Wilkoff, Bruce L; Aronica, Mark A; Svensson, Lars G; Taylor, James S

    2008-07-01

    Allergic reactions to endoprostheses are uncommon and reported in association with orthopaedic, dental, endovascular and other implanted devices. Hypersensitivity reactions to the biomaterials used in endovascular prostheses are among the infrequent reactions that may lead to local or systemic complications following cardiovascular therapeutic interventions. This article reviews potential immunotoxic effects of commonly used biomaterials. Reports of putative hypersensitivity reactions to endovascular devices, including coronary stents, perforated foramen occluders, pacemakers and implantable cardioverter defibrillators are also reviewed.

  19. Efficient path sampling on multiple reaction channels

    OpenAIRE

    van Erp, Titus S.

    2007-01-01

    Due to the time scale problem, rare events are not accessible by straight forward molecular dynamics. The presence of multiple reaction channels complicates the problem even further. The feasibility of the standard free energy based methods relies strongly on the success in finding a proper reaction coordinate. This can be very difficult task in high-dimensional complex systems and even more if several distinct reaction channels exist. Moreover, even if a proper reaction coordinate can be fou...

  20. Test Reactions to Study Efficiency of

    OpenAIRE

    Jasińska Magdalena

    2015-01-01

    Effects of mixing on the course of fast chemical reactions are relatively well understood, especially in homogeneous systems. This enables to design and operate chemical reactors with the goal to achieve a high yield of a desired product and use systems of complex reactions as a chemical probe (chemical test reactions) to identify progress of mixing and quality of mixture. Recently, a number of studies have focused on the application of chemical test reactions to identify energy efficiency of...

  1. Reactions of butadiyne. 1: The reaction with hydrogen atoms

    Science.gov (United States)

    Schwanebeck, W.; Warnatz, J.

    1984-01-01

    The reaction of hydrogen (H) atoms with butadiene (C4H2) was studied at room temperature in a pressure range between w mbar and 10 mbar. The primary step was an addition of H to C4H2 which is in its high pressure range at p 1 mbar. Under these conditions the following addition of a second H atom lies in the transition region between low and high pressure range. Vibrationally excited C4H4 can be deactivated to form buten-(1)-yne-(3)(C4H4) or decomposes into two C2H2 molecules. The rate constant at room temperature for primary step is given. The second order rate constant for the consumption of buten-(1)-yne-(3) is an H atom excess at room temperature is given.

  2. Reaction-Map of Organic Chemistry

    Science.gov (United States)

    Murov, Steven

    2007-01-01

    The Reaction-Map of Organic Chemistry lists all the most commonly studied reactions in organic chemistry on one page. The discussed Reaction-Map will act as another learning aide for the students, making the study of organic chemistry much easier.

  3. Severe photosensitivity reaction induced by topical diclofenac

    OpenAIRE

    Akat, Pramod B.

    2013-01-01

    Albeit uncommon, photosensitivity reaction induced by diclofenac can be an unfortunate adverse reaction complicating its use as a topical analgesic. We here present a case of a patient who suffered such a reaction as a result of exposure to diclofenac, employed as a topical analgesic for low backache. The lesions healed with conservative management without extensive scarring or other complications.

  4. Reaction-Map of Organic Chemistry

    Science.gov (United States)

    Murov, Steven

    2007-01-01

    The Reaction-Map of Organic Chemistry lists all the most commonly studied reactions in organic chemistry on one page. The discussed Reaction-Map will act as another learning aide for the students, making the study of organic chemistry much easier.

  5. Allergic reactions seen in orthodontic treatment

    Directory of Open Access Journals (Sweden)

    Hande Görücü Coşkuner

    2016-01-01

    Full Text Available Allergy can be defined as inappropriate and harmful response to harmless and ordinary materials. Allergic reactions, like in other fields of dentistry, can also be seen in the field of orthodontics. The reactions that occur against orthodontic materials can be seen as irritant or hypersensitivity reactions. The main reason of the irritant reactions is friction between soft tissues and orthodontic appliances. However, the reason of the hypersensitivity reactions is usually the antigenicity of the materials. Hypersensitivity reactions are usually seen as allergic contact dermatitis on face and neck; the occurrence of mucosal-gingival reactions and dermal and systemic reactions are rare. Latex, metal and acrylic resins are the most common allergens in orthodontics. Apart from these materials, allergic reactions can occur against bonding materials, extraoral appliances, disinfectants and antimicrobial agents. The reactions that occur against extraoral appliances usually result from metallic and elastic parts of the appliances or the appliance parts that are in contact with skin. Orthodontists should be aware of the allergic reactions to protect their patients’ health. The aim of this review was to evaluate the allergic reactions seen in orthodontic patients and discuss the cautions that orthodontists can take.

  6. Reaction Order Ambiguity in Integrated Rate Plots

    Science.gov (United States)

    Lee, Joe

    2008-01-01

    Integrated rate plots are frequently used in reaction kinetics to determine orders of reactions. It is often emphasised, when using this methodology in practice, that it is necessary to monitor the reaction to a substantial fraction of completion for these plots to yield unambiguous orders. The present article gives a theoretical and statistical…

  7. Severe photosensitivity reaction induced by topical diclofenac

    Directory of Open Access Journals (Sweden)

    Pramod B Akat

    2013-01-01

    Full Text Available Albeit uncommon, photosensitivity reaction induced by diclofenac can be an unfortunate adverse reaction complicating its use as a topical analgesic. We here present a case of a patient who suffered such a reaction as a result of exposure to diclofenac, employed as a topical analgesic for low backache. The lesions healed with conservative management without extensive scarring or other complications.

  8. The Catalytic Asymmetric Intramolecular Stetter Reaction.

    Science.gov (United States)

    de Alaniz, Javier Read; Rovis, Tomislav

    2009-05-01

    This account chronicles our efforts at the development of a catalytic asymmetric Stetter reaction using chiral triazolium salts as small molecule organic catalysts. Advances in the mechanistically related azolium-catalyzed asymmetric benzoin reaction are discussed, particularly as they apply to catalyst design. A chronological treatise of reaction discovery, catalyst optimization and reactivity extension follows.

  9. Nonadiabatic reaction of energetic molecules.

    Science.gov (United States)

    Bhattacharya, Atanu; Guo, Yuanqing; Bernstein, Elliot R

    2010-12-21

    Energetic materials store a large amount of chemical energy that can be readily converted into mechanical energy via decomposition. A number of different ignition processes such as sparks, shocks, heat, or arcs can initiate the excited electronic state decomposition of energetic materials. Experiments have demonstrated the essential role of excited electronic state decomposition in the energy conversion process. A full understanding of the mechanisms for the decomposition of energetic materials from excited electronic states will require the investigation and analysis of the specific topography of the excited electronic potential energy surfaces (PESs) of these molecules. The crossing of multidimensional electronic PESs creates a funnel-like topography, known as conical intersections (CIs). CIs are well established as a controlling factor in the excited electronic state decomposition of polyatomic molecules. This Account summarizes our current understanding of the nonadiabatic unimolecular chemistry of energetic materials through CIs and presents the essential role of CIs in the determination of decomposition pathways of these energetic systems. Because of the involvement of more than one PES, a decomposition process involving CIs is an electronically nonadiabatic mechanism. Based on our experimental observations and theoretical calculations, we find that a nonadiabatic reaction through CIs dominates the initial decomposition process of energetic materials from excited electronic states. Although the nonadiabatic behavior of some polyatomic molecules has been well studied, the role of nonadiabatic reactions in the excited electronic state decomposition of energetic molecules has not been well investigated. We use both nanosecond energy-resolved and femtosecond time-resolved spectroscopic techniques to determine the decomposition mechanism and dynamics of energetic species experimentally. Subsequently, we employ multiconfigurational methodologies (such as, CASSCF

  10. Kinetic studies of elementary chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Durant, J.L. Jr. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    This program concerning kinetic studies of elementary chemical reactions is presently focussed on understanding reactions of NH{sub x} species. To reach this goal, the author is pursuing experimental studies of reaction rate coefficients and product branching fractions as well as using electronic structure calculations to calculate transition state properties and reaction rate calculations to relate these properties to predicted kinetic behavior. The synergy existing between the experimental and theoretical studies allow one to gain a deeper insight into more complex elementary reactions.

  11. Electromagnetic effects on explosive reaction and plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tasker, Douglas G [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Mace, Jonathan L [Los Alamos National Laboratory; Pemberton, Steven J [Los Alamos National Laboratory; Sandoval, Thomas D [Los Alamos National Laboratory; Lee, Richard J [INDIAN HEAD DIVISION

    2010-01-01

    A number of studies have reported that electric fields can have quantifiable effects on the initiation and growth of detonation, yet the mechanisms of these effects are not clear. Candidates include Joule heating of the reaction zone, perturbations to the activation energy for chemical reaction, reduction of the Peierls energy barrier that facilitates dislocation motion, and acceleration of plasma projected from the reaction zone. In this study the possible role of plasma in the initiation and growth of explosive reaction is investigated. The effects of magnetic and electric field effects on reaction growth will be reviewed and recent experiments reported.

  12. Incidents of chemical reactions in cell equipment

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, N.M.; Barlow, C.R. [Uranium Enrichment Organization, Oak Ridge, TN (United States)

    1991-12-31

    Strongly exothermic reactions can occur between equipment structural components and process gases under certain accident conditions in the diffusion enrichment cascades. This paper describes the conditions required for initiation of these reactions, and describes the range of such reactions experienced over nearly 50 years of equipment operation in the US uranium enrichment program. Factors are cited which can promote or limit the destructive extent of these reactions, and process operations are described which are designed to control the reactions to minimize equipment damage, downtime, and the possibility of material releases.

  13. Scratching the surface of allergic transfusion reactions.

    Science.gov (United States)

    Savage, William J; Tobian, Aaron A R; Savage, Jessica H; Wood, Robert A; Schroeder, John T; Ness, Paul M

    2013-06-01

    Allergic transfusion reactions (ATRs) are a spectrum of hypersensitivity reactions that are the most common adverse reaction to platelets and plasma, occurring in up to 2% of transfusions. Despite the ubiquity of these reactions, little is known about their mechanism. In a small subset of severe reactions, specific antibody has been implicated as causal, although this mechanism does not explain all ATRs. Evidence suggests that donor, product, and recipient factors are involved, and it is possible that many ATRs are multifactorial. Further understanding of the mechanisms of ATRs is necessary so that rationally designed and cost-effective prevention measures can be developed.

  14. A reversible nanoconfined chemical reaction.

    Science.gov (United States)

    Nielsen, Thomas K; Bösenberg, Ulrike; Gosalawit, Rapee; Dornheim, Martin; Cerenius, Yngve; Besenbacher, Flemming; Jensen, Torben R

    2010-07-27

    Hydrogen is recognized as a potential, extremely interesting energy carrier system, which can facilitate efficient utilization of unevenly distributed renewable energy. A major challenge in a future "hydrogen economy" is the development of a safe, compact, robust, and efficient means of hydrogen storage, in particular, for mobile applications. Here we report on a new concept for hydrogen storage using nanoconfined reversible chemical reactions. LiBH4 and MgH2 nanoparticles are embedded in a nanoporous carbon aerogel scaffold with pore size Dmax approximately 21 nm and react during release of hydrogen and form MgB2. The hydrogen desorption kinetics is significantly improved compared to bulk conditions, and the nanoconfined system has a high degree of reversibility and stability and possibly also improved thermodynamic properties. This new scheme of nanoconfined chemistry may have a wide range of interesting applications in the future, for example, within the merging area of chemical storage of renewable energy.

  15. Radiation reaction of multipole moments

    Science.gov (United States)

    Kazinski, P. O.

    2007-08-01

    A Poincaré-invariant description is proposed for the effective dynamics of a localized system of charged particles in classical electrodynamics in terms of the intrinsic multipole moments of the system. A relativistic-invariant definition for the intrinsic multipole moments of a system of charged particles is given. A new generally covariant action functional for a relativistic perfect fluid is proposed. In the case of relativistic charged dust, it is proven that the description of the problem of radiation reaction of multipole moments by the model of particles is equivalent to the description of this problem by a hydrodynamic model. An effective model is obtained for a pointlike neutral system of charged particles that possesses an intrinsic dipole moment, and the free dynamics of this system is described. The bound momentum of a point dipole is found.

  16. Radiation reaction for multipole moments

    CERN Document Server

    Kazinski, P O

    2006-01-01

    We propose a Poincare-invariant description for the effective dynamics of systems of charged particles by means of intrinsic multipole moments. To achieve this goal we study the effective dynamics of such systems within two frameworks -- the particle itself and hydrodynamical one. We give a relativistic-invariant definition for the intrinsic multipole moments both pointlike and extended relativistic objects. Within the hydrodynamical framework we suggest a covariant action functional for a perfect fluid with pressure. In the case of a relativistic charged dust we prove the equivalence of the particle approach to the hydrodynamical one to the problem of radiation reaction for multipoles. As the particular example of a general procedure we obtain the effective model for a neutral system of charged particles with dipole moment.

  17. [Paranoid syndrome, paranoid reaction, paranoia].

    Science.gov (United States)

    Pavlovský, P

    2006-01-01

    The term paranoid is derived from the Greek word paranoia meaning nadnese. It does not only mean self-reference, but there are various personality features as they are hostility, a tendency towards aggressiveness, irritability, a lack of sense of humour, feelings of overestimation of one-self and a tendency towards accusations. These features may appear also within normal psychology and they becomeclinically important after thein increase of intensity and conspicuousness (los sof hearing, long-term abuse of alcohol and psychostimulants) and organic disorders of the brain may contribute to the development of paranoidity. A mechanism of projection is considered as a decivise factor from the point of view of dynamic psychiatry. Clinically unimportant sign sof paranoidity can be observed due to unusual situations. If a paranoid reaction becomes more serious, formation of a paranoid delusion should be taken to account. In our koncept the term paranoid and paranoidity should be used only as a psychopathological term.

  18. Reaction mechanisms of DNA photolyase.

    Science.gov (United States)

    Brettel, Klaus; Byrdin, Martin

    2010-12-01

    DNA photolyase uses visible light and a fully reduced flavin cofactor FADH(-) to repair major UV-induced lesions in DNA, the cyclobutane pyrimidine dimers (CPDs). Electron transfer from photoexcited FADH(-) to CPD, splitting of the two intradimer bonds, and back electron transfer to the transiently formed flavin radical FADH° occur in overall 1ns. Whereas the kinetics of FADH° was resolved, the DNA-based intermediates escaped unambiguous detection yet. Another light reaction, named photoactivation, reduces catalytically inactive FADH° to FADH(-) without implication of DNA. It involves electron hopping along a chain of three tryptophan residues in 30ps, as elucidated in detail by transient absorption spectroscopy. The same triple tryptophan chain is found in cryptochrome blue-light photoreceptors and may be involved in their primary photoreaction.

  19. A Networks Approach to Modeling Enzymatic Reactions.

    Science.gov (United States)

    Imhof, P

    2016-01-01

    Modeling enzymatic reactions is a demanding task due to the complexity of the system, the many degrees of freedom involved and the complex, chemical, and conformational transitions associated with the reaction. Consequently, enzymatic reactions are not determined by precisely one reaction pathway. Hence, it is beneficial to obtain a comprehensive picture of possible reaction paths and competing mechanisms. By combining individually generated intermediate states and chemical transition steps a network of such pathways can be constructed. Transition networks are a discretized representation of a potential energy landscape consisting of a multitude of reaction pathways connecting the end states of the reaction. The graph structure of the network allows an easy identification of the energetically most favorable pathways as well as a number of alternative routes.

  20. Heuristics-Guided Exploration of Reaction Mechanisms

    CERN Document Server

    Bergeler, Maike; Proppe, Jonny; Reiher, Markus

    2015-01-01

    For the investigation of chemical reaction networks, the efficient and accurate determination of all relevant intermediates and elementary reactions is inevitable. The complexity of such a network may grow rapidly, in particular if reactive species are involved that might cause a myriad of side reactions. Without automation, a complete investigation of complex reaction mechanisms is tedious and possibly unfeasible. Therefore, only the expected dominant reaction paths of a chemical reaction network (e.g., a catalytic cycle or an enzymatic cascade) are usually explored in practice. Here, we present a computational protocol that constructs such networks in a parallelized and automated manner. Molecular structures of reactive complexes are generated based on heuristic rules and subsequently optimized by electronic-structure methods. Pairs of reactive complexes related by an elementary reaction are then automatically detected and subjected to an automated search for the connecting transition state. The results are...

  1. Computed potential energy surfaces for chemical reactions

    Science.gov (United States)

    Walch, Stephen P.

    1994-01-01

    Quantum mechanical methods have been used to compute potential energy surfaces for chemical reactions. The reactions studied were among those believed to be important to the NASP and HSR programs and included the recombination of two H atoms with several different third bodies; the reactions in the thermal Zeldovich mechanism; the reactions of H atom with O2, N2, and NO; reactions involved in the thermal De-NO(x) process; and the reaction of CH(squared Pi) with N2 (leading to 'prompt NO'). These potential energy surfaces have been used to compute reaction rate constants and rates of unimolecular decomposition. An additional application was the calculation of transport properties of gases using a semiclassical approximation (and in the case of interactions involving hydrogen inclusion of quantum mechanical effects).

  2. Explorations into Chemical Reactions and Biochemical Pathways.

    Science.gov (United States)

    Gasteiger, Johann

    2016-12-01

    A brief overview of the work in the research group of the present author on extracting knowledge from chemical reaction data is presented. Methods have been developed to calculate physicochemical effects at the reaction site. It is shown that these physicochemical effects can quite favourably be used to derive equations for the calculation of data on gas phase reactions and on reactions in solution such as aqueous acidity of alcohols or carboxylic acids or the hydrolysis of amides. Furthermore, it is shown that these physicochemical effects are quite effective for assigning reactions into reaction classes that correspond to chemical knowledge. Biochemical reactions constitute a particularly interesting and challenging task for increasing our understanding of living species. The BioPath.Database is a rich source of information on biochemical reactions and has been used for a variety of applications of chemical, biological, or medicinal interests. Thus, it was shown that biochemical reactions can be assigned by the physicochemical effects into classes that correspond to the classification of enzymes by the EC numbers. Furthermore, 3D models of reaction intermediates can be used for searching for novel enzyme inhibitors. It was shown in a combined application of chemoinformatics and bioinformatics that essential pathways of diseases can be uncovered. Furthermore, a study showed that bacterial flavor-forming pathways can be discovered.

  3. ReactionPredictor: prediction of complex chemical reactions at the mechanistic level using machine learning.

    Science.gov (United States)

    Kayala, Matthew A; Baldi, Pierre

    2012-10-22

    Proposing reasonable mechanisms and predicting the course of chemical reactions is important to the practice of organic chemistry. Approaches to reaction prediction have historically used obfuscating representations and manually encoded patterns or rules. Here we present ReactionPredictor, a machine learning approach to reaction prediction that models elementary, mechanistic reactions as interactions between approximate molecular orbitals (MOs). A training data set of productive reactions known to occur at reasonable rates and yields and verified by inclusion in the literature or textbooks is derived from an existing rule-based system and expanded upon with manual curation from graduate level textbooks. Using this training data set of complex polar, hypervalent, radical, and pericyclic reactions, a two-stage machine learning prediction framework is trained and validated. In the first stage, filtering models trained at the level of individual MOs are used to reduce the space of possible reactions to consider. In the second stage, ranking models over the filtered space of possible reactions are used to order the reactions such that the productive reactions are the top ranked. The resulting model, ReactionPredictor, perfectly ranks polar reactions 78.1% of the time and recovers all productive reactions 95.7% of the time when allowing for small numbers of errors. Pericyclic and radical reactions are perfectly ranked 85.8% and 77.0% of the time, respectively, rising to >93% recovery for both reaction types with a small number of allowed errors. Decisions about which of the polar, pericyclic, or radical reaction type ranking models to use can be made with >99% accuracy. Finally, for multistep reaction pathways, we implement the first mechanistic pathway predictor using constrained tree-search to discover a set of reasonable mechanistic steps from given reactants to given products. Webserver implementations of both the single step and pathway versions of Reaction

  4. Reaction products of chlorine dioxide.

    Science.gov (United States)

    Stevens, A A

    1982-01-01

    Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxide treatment of organic materials are oxidized species, some of which also contain chlorine. The relative amounts of species types may depend on the amount of chlorine dioxide residual maintained and the concentration and nature of the organic material present in the source water. The trend toward lower concentrations of chlorinated by-products with increasing ClO2 concentration, which was observed with phenols, has not been observed with natural humic materials as measured by the organic halogen parameter. Organic halogen concentrations have been shown to increase with increasing chlorine dioxide dose, but are much lower than those observed when chlorine is applied. Aldehydes have been detected as apparent by-products of chlorine dioxide oxidation reactions in a surface water that is a drinking water source. Some other nonchlorinated products of chlorine dioxide treatment may be quinones and epoxides. The extent of formation of these moieties within the macromolecular humic structure is also still unknown. PMID:7151750

  5. Anaphylactic reaction to lupine flour.

    Science.gov (United States)

    Brennecke, Sabine; Becker, Wolf-Meinhard; Lepp, Ute; Jappe, Uta

    2007-09-01

    Roasted lupine seeds have been used as snack food in Mediterranean countries for years. Since the 1990s, lupine flour has been used as a substitute for or additive to other flours in countries of the European Union; usually the amount is so low that no declaration is required. Since 1994, a number of cases of immediate-type allergy to lupine flour-containing products have been published. A 52-year-old woman developed facial and mucosal edema, followed by dizziness and shortness of breath a few minutes after ingestion of a nut croissant containing lupine flour; she required emergency care. Allergy diagnostic tests revealed a total IgE of 116 kU/l, a highly elevated concentration of IgE specific for lupine seed (42.9 kU/l) and birch pollen IgE of 2.57 kU/l. Skin prick test with native lupine flour was strongly positive. Allergy against lupine seeds may develop de novo or via cross-reactivity to legumes, particularly peanuts, the latter being detectable in up to 88% of cases, founded on a strong sequence similarity between lupine and peanut allergens. In our patient, no cross-reactivity could be detected via immunoblotting, indicating a rare monovalent sensitization to lupine flour. Treatment consists of avoidance of lupine flour-containing products. Patients with proven peanut allergy should also avoid lupine flour because of the major risk of cross-reaction.

  6. 2005 Chemical Reactions at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cynthia M. Friend

    2006-03-14

    The Gordon Research Conference (GRC) on 2005 Chemical Reactions at Surfaces was held at Ventura Beach Marriott, Ventura California from February 13, 2005 through February 18, 2005. The Conference was well-attended with 124 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions. In order that more scientists could communicate their most recent results, poster presentation time was scheduled. Attached is a copy of the formal schedule and speaker program and the poster program. In addition to these formal interactions, 'free time' was scheduled to allow informal discussions. Such discussions are fostering new collaborations and joint efforts in the field.

  7. Interfacial reactions in lithium batteries

    Science.gov (United States)

    Chen, Zonghai; Amine, Rachid; Ma, Zi-Feng; Amine, Khalil

    2017-08-01

    The lithium-ion battery was first commercially introduced by Sony Corporation in 1991 using LiCoO2 as the cathode material and mesocarbon microbeads (MCMBs) as the anode material. After continuous research and development for 25 years, lithium-ion batteries have been the dominant energy storage device for modern portable electronics, as well as for emerging applications for electric vehicles and smart grids. It is clear that the success of lithium-ion technologies is rooted to the existence of a solid electrolyte interphase (SEI) that kinetically suppresses parasitic reactions between the lithiated graphitic anodes and the carbonate-based non-aqueous electrolytes. Recently, major attention has been paid to the importance of a similar passivation/protection layer on the surface of cathode materials, aiming for a rational design of high-energy-density lithium-ion batteries with extended cycle/calendar life. In this article, the physical model of the SEI, as well as recent research efforts to understand the nature and role of the SEI are summarized, and future perspectives on this important research field will also be presented.

  8. Piezonuclear reactions - do they exist?

    CERN Document Server

    Ericsson, G; Sjöstrand, H; Traneus, E

    2009-01-01

    In a number of recent articles in this journal F. Cardone and collaborators have claimed the observation of several striking nuclear phenomena which they attribute to "piezonuclear reactions". One such claim [Phys. Lett. A 373 (2009) 1956] is that subjecting a solution of 228Th to cavitation leads to a "transformation" of thorium nuclei that is 104 times faster than the normal nuclear decay for this isotope. In a "Comment" [Phys. Lett. A 373 (2009) 3795] to the thorium work, we have criticized the evidence provided for this claim. In a "Reply" [Phys. Lett. A 373 (2009) 3797] Cardone et al. answer only some minor points but avoid addressing the real issue. The information provided in their Reply displays a worrying lack of control of their experimental situation and the data they put forward as evidence for their claims. We point out several shortcomings and errors in the described experimental preparations, set-up and reporting, as well as in the data analysis. We conclude that the evidence presented by Cardo...

  9. Reaction between mullite and polytitanocarbosilane

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Y.; Matsura, T. [Kagoshima Univ. (Japan). Dept. of Appl. Chem.; Shibuya, M. [Ube Industries Ltd., Tyranno Fiber Development Project (Japan)

    1999-03-01

    Infiltration and subsequent pyrolysis of inorganic polymer in the spaces of long fibers / mullite powder systems may be a successful processing method to reduce the damage of fibers and to decrease the shrinkage of the matrix during heating. This paper describes the chemical reaction between polytitanocarbosilane and mullite as a first step in the processing of mullite matrix composites. A mullite powder of 30 vol% was mixed with a polytitanocarbosilane (50 wt%) / xylene (50 wt%) solution for 24 h, and the suspension was formed into thick films by doctor blade. The green sheets were hot-pressed at 1400-1600 C in a N{sub 2} atmosphere. The composites consisted of mullite, sialon with a composition of Si{sub 2}Al{sub 3}O{sub 7}N or Si{sub 12}Al{sub 18}O{sub 39}N{sub 8}, {alpha}-Al{sub 2}O{sub 3}, {beta}-SiC and TiN. The formation of these phases were thermodynamically discussed in the system of mullite - C (supplied from polytitianocarbosilane) - N{sub 2}. (orig.) 11 refs.

  10. Reaction time and psychophysiological activity.

    Science.gov (United States)

    Sersen, E A; Clausen, J; Lidsky, A

    1982-04-01

    Disjunctive reaction times (RT) involving two interstimulus intervals were obtained from 10 subjects during 4 sessions while recording heart period, skin conductance, and EEG. Multiple regression analysis indicated complex relationships between RT and skin conductance and heart period which varied with session level. The relationship of RT and skin conductance was predominantly linear but positive when level of skin conductance was low and negative when high. Heart period showed a predominantly curvilinear trend which also varied with level during the session. Fastest RTs tended to occur with long heart periods in short heart period sessions and vice versa. Fast RTs were also accompanied by relatively low EEG power before and after stimulation and by higher EEG frequency after the stimulus. The pattern of findings did not fully accord with the expectations of activation theory, and the proportion of RT variance accounted for was small. It is suggested that activation may vary to maintain a constant level of motor performance. Faster RT may occur under relaxed conditions and high arousal, and concentrated attentiveness may be an attempt to compensate for boredom or distraction.

  11. Disulfiram-like reaction with ornidazole

    Directory of Open Access Journals (Sweden)

    Sharma V

    2009-01-01

    Full Text Available Many drugs are implicated in causation of disulfiram-like reaction. The disulfiram-like reaction can vary in severity and can occasionally be fatal. The reaction is believed to result from inhibition of metabolism of acetaldehyde to acetate by inhibition of aldehyde dehydrogenase. The increase in serum acetaldehyde results in unpleasant clinical manifestations. Metronidazole is known to cause disulfiram-like reaction. Although no previous report has implicated ornidazole in causation of disulfiram-like reaction, caution has been advised with the use of all imidazoles. We report the case of a 48-year-old male, who was taking ornidazole and developed features of disulfiram-like reaction after taking alcohol. The patient was managed with supportive measures and improved. The report highlights the need for clinicians to advise patients to restrict intake of alcohol if they are being prescribed imidazole derivatives.

  12. Surface reactions in microelectronics process technology.

    Science.gov (United States)

    Levitin, Galit; Hess, Dennis W

    2011-01-01

    Current integrated circuit (IC) manufacturing consists of more than 800 process steps, nearly all of which involve reactions at surfaces that significantly impact device yield and performance. From initial surface preparation through film deposition, patterning, etching, residue removal, and metallization, an understanding of surface reactions and interactions is critical to the successful continuous scaling, yield, and reliability of electronic devices. In this review, some of the most important surface reactions that drive the development of microelectronic device fabrication are described. The reactions discussed do not constitute comprehensive coverage of this topic in IC manufacture but have been selected to demonstrate the importance of surface/interface reactions and interactions in the development of new materials, processing sequences, and process integration challenges. Specifically, the review focuses on surface reactions related to surface cleaning/preparation, semiconductor film growth, dielectric film growth, metallization, and etching (dry and wet).

  13. Reaction Coordinates and Mechanistic Hypothesis Tests.

    Science.gov (United States)

    Peters, Baron

    2016-05-27

    Reaction coordinates are integral to several classic rate theories that can (a) predict kinetic trends across conditions and homologous reactions, (b) extract activation parameters with a clear physical interpretation from experimental rates, and (c) enable efficient calculations of free energy barriers and rates. New trajectory-based rare events methods can provide rates directly from dynamical trajectories without a reaction coordinate. Trajectory-based frameworks can also generate ideal (but abstract) reaction coordinates such as committors and eigenfunctions of the master equation. However, rates and mechanistic insights obtained from trajectory-based methods and abstract coordinates are not readily generalized across simulation conditions or reaction families. We discuss methods for identifying physically meaningful reaction coordinates, including committor analysis, variational transition state theory, Kramers-Langer-Berezhkovskii-Szabo theory, and statistical inference methods that can use path sampling data to screen, mix, and optimize thousands of trial coordinates. Special focus is given to likelihood maximization and inertial likelihood maximization approaches.

  14. Test Reactions to Study Efficiency of

    Directory of Open Access Journals (Sweden)

    Jasińska Magdalena

    2015-06-01

    Full Text Available Effects of mixing on the course of fast chemical reactions are relatively well understood, especially in homogeneous systems. This enables to design and operate chemical reactors with the goal to achieve a high yield of a desired product and use systems of complex reactions as a chemical probe (chemical test reactions to identify progress of mixing and quality of mixture. Recently, a number of studies have focused on the application of chemical test reactions to identify energy efficiency of mixing, being a convenient way of comparing mixers and reactors in terms of their mixing efficiency. This review offers a presentation of chemical test reactions available in the literature and methods of applications of test reactions to identify the energy efficiency of mixing. Also methods to assess the extent of micromixing by measuring product distribution or segregation index, and to determine the time constant for mixing are presented for single phase homogeneous systems and two-phase liquid-liquid systems.

  15. Reaction Coordinates and Mechanistic Hypothesis Tests

    Science.gov (United States)

    Peters, Baron

    2016-05-01

    Reaction coordinates are integral to several classic rate theories that can (a) predict kinetic trends across conditions and homologous reactions, (b) extract activation parameters with a clear physical interpretation from experimental rates, and (c) enable efficient calculations of free energy barriers and rates. New trajectory-based rare events methods can provide rates directly from dynamical trajectories without a reaction coordinate. Trajectory-based frameworks can also generate ideal (but abstract) reaction coordinates such as committors and eigenfunctions of the master equation. However, rates and mechanistic insights obtained from trajectory-based methods and abstract coordinates are not readily generalized across simulation conditions or reaction families. We discuss methods for identifying physically meaningful reaction coordinates, including committor analysis, variational transition state theory, Kramers-Langer-Berezhkovskii-Szabo theory, and statistical inference methods that can use path sampling data to screen, mix, and optimize thousands of trial coordinates. Special focus is given to likelihood maximization and inertial likelihood maximization approaches.

  16. Controlling chemical reactions of a single particle

    CERN Document Server

    Ratschbacher, Lothar; Sias, Carlo; Köhl, Michael

    2012-01-01

    The control of chemical reactions is a recurring theme in physics and chemistry. Traditionally, chemical reactions have been investigated by tuning thermodynamic parameters, such as temperature or pressure. More recently, physical methods such as laser or magnetic field control have emerged to provide completely new experimental possibilities, in particular in the realm of cold collisions. The control of reaction pathways is also a critical component to implement molecular quantum information processing. For these undertakings, single particles provide a clean and well-controlled experimental system. Here, we report on the experimental tuning of the exchange reaction rates of a single trapped ion with ultracold neutral atoms by exerting control over both their quantum states. We observe the influence of the hyperfine interaction on chemical reaction rates and branching ratios, and monitor the kinematics of the reaction products. These investigations advance chemistry with single trapped particles towards achi...

  17. Triple click reaction strategy for macromolecular diversity.

    Science.gov (United States)

    Tunca, Umit

    2013-01-11

    This Feature Article focuses on the rapidly emerging concept of the "triple click reactions" towards the design and synthesis of macromolecules with well-defined topology and chemical composition, and also precise molecular weight and narrow molecular weight distribution. The term "triple click reaction" used in this feature article is based on the utilization of three chemically and mechanistically different click reactions for polymer-polymer conjugation and post-modification of the polymers. Three sequential click reactions of which two are identical should not be considered to be triple click reactions. The triple click reaction strategy for polymer conjugation and post-modification of polymers is classified in this article based on the resultant architectures: linear and non-linear structures. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Catalytic Reactions in Heavy-ion Collisions

    CERN Document Server

    Kolomeitsev, E E

    2011-01-01

    We discuss a new type of reactions of a phi meson production on hyperons, pi Y--> phi Y and anti-kaons bar-K N --> phi Y. These reactions are not suppressed according to Okubo-Zweig-Iizuka rule and can be a new efficient source of phi mesons in a nucleus-nucleus collision. We discuss how these reactions can affect the centrality dependence and the rapidity distributions of the phi yield.

  19. Catalytic reactions in heavy-ion collisions

    Science.gov (United States)

    Kolomeitsev, E. E.; Tomášik, B.

    2012-06-01

    We discuss a new type of reactions of a ϕ-meson production on hyperons, πY → ϕY and antikaons -KN → ϕY. These reactions are not suppressed according to Okubo-Zweig-Iizuka rule and can be a new efficient source of ϕ mesons in a nucleus-nucleus collision. We discuss how these reactions can affect the centrality dependence and the rapidity distributions of the ϕ yield.

  20. [Rare, severe hypersensitivity reaction to potassium iodide].

    Science.gov (United States)

    Korsholm, Anne Sofie; Ebbehøj, Eva; Richelsen, Bjørn

    2014-07-07

    The literature reports a large variety of adverse reactions to potassium iodide. A severe hypersensitivity reaction to potassium iodide in a 51-year-old woman with Graves' thyrotoxicosis is described. Following administration the patient developed sialadenitis, conjunctivitis, stomatitis and acneiform iododerma that responded dramatically to withdrawal of the potassium iodide and administration with corticosteroids. Awareness of these adverse reactions may prevent prolonged hospitalization and unnecessary tests and treatments.

  1. Kinetics of Model Reactions for Interfacial Polymerization

    Directory of Open Access Journals (Sweden)

    Henry Hall

    2012-02-01

    Full Text Available To model the rates of interfacial polycondensations, the rates of reaction of benzoyl chloride and methyl chloroformate with various aliphatic monoamines in acetonitrile were determined at 25 °C. Buffering with picric acid slowed these extremely fast reactions so the rate constants could be determined from the rate of disappearance of picrate ion. The rates of the amine reactions correlated linearly with their Swain-Scott nucleophilicities.

  2. Negative Temperature Coefficient in Chemical Reactions

    Science.gov (United States)

    Leenson, I. A.; Sergeev, Gleb B.

    1984-05-01

    A systematic analysis of reactions whose rate decreases with increase of temperature is presented. The possibility of a negative temperature coefficient in the elementary reactions is examined from the standpoint of the transition state theory and of collision theory. The mechanisms of complex reactions in which the temperature dependence of the rate is anomalous are discussed, and possible reasons for the anomaly are examined. The bibliography contains 175 references.

  3. Modelling Chemical Reasoning to Predict Reactions

    OpenAIRE

    Segler, Marwin H. S.; Waller, Mark P.

    2016-01-01

    The ability to reason beyond established knowledge allows Organic Chemists to solve synthetic problems and to invent novel transformations. Here, we propose a model which mimics chemical reasoning and formalises reaction prediction as finding missing links in a knowledge graph. We have constructed a knowledge graph containing 14.4 million molecules and 8.2 million binary reactions, which represents the bulk of all chemical reactions ever published in the scientific literature. Our model outpe...

  4. The mechanism of the modified Ullmann reaction

    OpenAIRE

    Sperotto, Elena; Klink, Gerard P.M. van; van Koten, Gerard; Vries, Johannes G. de

    2010-01-01

    The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) made these reactions truly catalytic, with catalyst amounts as low as 1 mol% or even lower. Since these catalysts are homogeneous, it has opened up the possibility to investigate the mechanism of the...

  5. A Unified Theory of Chemical Reactions

    CERN Document Server

    Aubry, S

    2014-01-01

    We propose a new and general formalism for elementary chemical reactions where quantum electronic variables are used as reaction coordinates. This formalism is in principle applicable to all kinds of chemical reactions ionic or covalent. Our theory reveals the existence of an intermediate situation between ionic and covalent which may be almost barrierless and isoenegetic and which should be of high interest for understanding biochemistry.

  6. Preventing Corrosion by Controlling Cathodic Reaction Kinetics

    Science.gov (United States)

    2016-03-25

    Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith...dominate the metal’s cathodic behavior. Within an alkaline environment, we expect the following reduction reactions to be catalyzed on the oxide

  7. Reaction torque minimization techniques for articulated payloads

    Science.gov (United States)

    Kral, Kevin; Aleman, Roberto M.

    1988-01-01

    Articulated payloads on spacecraft, such as antenna telemetry systems and robotic elements, impart reaction torques back into the vehicle which can significantly affect the performance of other payloads. This paper discusses ways to minimize the reaction torques of articulated payloads through command-shaping algorithms and unique control implementations. The effects of reaction torques encountered on Landsat are presented and compared with simulated and measured data of prototype systems employing these improvements.

  8. Chemical-reaction model for Mexican wave

    Science.gov (United States)

    Nagatani, Takashi

    2003-05-01

    We present a chemical-reaction model to describe the Mexican wave ( La Ola) in football stadia. The spectator's action is described in terms of chemical reactions. The model is governed by three reaction rates k 1, k 2, and k3. We study the nonlinear waves on one- and two-dimensional lattices. The Mexican wave is formulated as a clockwise forwardly propagating wave. Waves are growing or disappear, depending on the values of reaction rates. In the specific case of k1= k2= k3=1, the nonlinear-wave equation produces a propagating pulse like soliton.

  9. Screened Thermonuclear Reaction Rates on Magnetar Surfaces

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-Lin; LUO Zhi-Quan; LIU Jing-Jing; LAI Xiang-Jun

    2008-01-01

    Improving Salpeter's method, we discuss the effect of superstrong magnetic fields (such as those of magnetars) on thermonuclear reaction rates. These most interesting reactions, including the hydrogen burning by the CNO cycle and the helium burning by the triple alpha reaction, are investigated as examples on the magnetar surfaces. The obtained result shows that the superstrong magnetic fields can increase the thermonuclear reaction rates by many orders of magnitude. The enhancement may have significant influence for further study research of the magnetars, especially for the x-ray luminosity observation and the evolution of magnetars.

  10. Chemical reactions in low-g

    Science.gov (United States)

    Grodzka, P. G.; Facemire, B. R.

    1978-01-01

    The Apollo-Soyuz flight experiment, 'Chemical Foams' demonstrated that foams and air/liquid dispersions are much more stable in low-gravity than on the ground. It thus should be possible to conduct unique chemical reactions in space foams. The low-g results and subsequent ground work on the formaldehyde clock reaction indicate that the reaction is strongly influenced by (1) dissociated and undissociated solution species being adsorbed at solid/liquid and gas/liquid surfaces and (2) chemical reaction rates apparently being affected by long-range forces determined by the liquid mass and the extent and nature of all surface interfaces.

  11. Catalytic Wittig and aza-Wittig reactions

    Directory of Open Access Journals (Sweden)

    Zhiqi Lao

    2016-11-01

    Full Text Available This review surveys the literature regarding the development of catalytic versions of the Wittig and aza-Wittig reactions. The first section summarizes how arsenic and tellurium-based catalytic Wittig-type reaction systems were developed first due to the relatively easy reduction of the oxides involved. This is followed by a presentation of the current state of the art regarding phosphine-catalyzed Wittig reactions. The second section covers the field of related catalytic aza-Wittig reactions that are catalyzed by both phosphine oxides and phosphines.

  12. Carbon-Fixing Reactions of Photosynthesis.

    Science.gov (United States)

    2016-07-01

    Summaryplantcell;28/7/tpc.116.tt0716/FIG1F1fig1Photosynthesis in plants converts the energy of sunlight into chemical energy. Although photosynthesis involves many proteins and catalytic processes, it often is described as two sets of reactions, the light-dependent reactions and the carbon-fixing reactions. This lesson introduces the core biochemistry of the carbon-fixing reactions of photosynthesis, as well as its variations, C4 and CAM. Finally, it addresses how and why plants are affected by rising atmospheric CO2 levels, and research efforts to increase photosynthetic efficiency in current and future conditions. © 2016 American Society of Plant Biologists. All rights reserved.

  13. Acute anaphylactoid reactions during hemodialysis in France.

    Science.gov (United States)

    Forêt, M; Kuentz, F; Meftahi, H; Milongo, R; Hachache, T; Elsener, M; Dechelette, E; Cordonnier, D

    1987-04-01

    A retrospective survey of anaphylactoid reactions during dialysis in France was conducted. In 52 of 112 hemodialysis units surveyed 111 patients who had suffered one or more anaphylactoid reactions during dialysis were identified. According to the Hamilton/Adkinson classification, in 31 patients reactions were minor, in 54 patients moderate, and in 26 patients severe. Four patients died of their reactions. A preponderance of reactions (75 and 11%) occurred with cuprammonium cellulose hollow-fiber and plate dialyzers, respectively. Severe dialyzer reactions were found to occur more frequently after the long (weekend) interdialytic interval. In an in vitro study, six brands of cuprammonium cellulose hollow-fiber dialyzers were rinsed with water and the eluates analyzed by size exclusion chromatography for contaminant particles. Substantial variation in the amount of extractable material was found between dialyzers of different brands, despite the fact that all dialyzers used membranes from the same manufacturer. Previous data by others has suggested that this extractable material is a derivative of cellulose. Results of our epidemiologic survey in France are similar to those previously reported in the United States and suggest an increased incidence of dialyzer reactions with ethylene oxide-sterilized cuprammonium cellulose dialyzers. The presence of cellulose-derived particles in the rinsing fluid of such dialyzers and the possible increased incidence of reactions after the long (weekend) interdialytic interval suggest that allergy to cellulose-derived particles eluted from cellulosic dialyzers may contribute to dialyzer hypersensitivity reactions.

  14. A study on sodium-concrete reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jae Heum; Min, Byong Hun [Suwon University, Suwon (Korea, Republic of)

    1997-07-01

    A small sodium-concrete reaction facility was designed, manufactured and installed. this facility has been operated under inert gas(N{sub 2}) with different experimental variables such as sodium injection temperature, injection amount of sodium, aging period of concrete, sodium reservoir temperature. As a result, it was found that sodium injection temperature and injected amount of sodium has little effect on sodium-concrete reaction. However, sodium reservoir temperature and aging period of concrete has relatively high impact on sodium-concrete reaction. Sodium-concrete reaction model has also been developed and compared with experimental results. (Author) 51 refs., 16 tabs., 64 figs.

  15. Time scale in quasifission reactions

    Energy Technology Data Exchange (ETDEWEB)

    Back, B.B.; Paul, P.; Nestler, J. [and others

    1995-08-01

    The quasifission process arises from the hindrance of the complete fusion process when heavy-ion beams are used. The strong dissipation in the system tends to prevent fusion and lead the system towards reseparation into two final products of similar mass reminiscent of a fission process. This dissipation slows down the mass transfer and shape transformation and allows for the emission of high energy {gamma}-rays during the process, albeit with a low probability. Giant Dipole {gamma} rays emitted during this time have a characteristic spectral shape and may thus be discerned in the presence of a background of {gamma} rays emitted from the final fission-like fragments. Since the rate of GDR {gamma} emission is very well established, the strength of this component may therefore be used to measure the timescale of the quasifission process. In this experiment we studied the reaction between 368-MeV {sup 58}Ni and a {sup 165}Ho target, where deep inelastic scattering and quasifission processes are dominant. Coincidences between fission fragments (detected in four position-sensitive avalanche detectors) and high energy {gamma} rays (measured in a 10{close_quotes} x 10{close_quotes} actively shielded NaI detector) were registered. Beams were provided by the Stony Brook Superconducting Linac. The {gamma}-ray spectrum associated with deep inelastic scattering events is well reproduced by statistical cooling of projectile and target-like fragments with close to equal initial excitation energy sharing. The y spectrum associated with quasifission events is well described by statistical emission from the fission fragments alone, with only weak evidence for GDR emission from the mono-nucleus. A 1{sigma} limit of t{sub ss} < 11 x 10{sup -21} s is obtained for the mono-nucleus lifetime, which is consistent with the lifetime obtained from quasifission fragment angular distributions. A manuscript was accepted for publication.

  16. Combined online spectroscopic, calorimetric, and chemometric analysis: reaction enthalpy determinations in single and parallel reactions.

    Science.gov (United States)

    Tjahjono, Martin; Widjaja, Effendi; Garland, Marc

    2009-06-02

    Calorimetry and signal processing: Vibrational spectroscopies, heat-flow microcalorimetry, and multivariate analysis are combined to decouple the reaction enthalpies of parallel reactions [picture: see text]. This methodology allows the evaluation of reaction enthalpy from complex systems without recourse to conventional kinetic modeling. Simultaneous in situ/online spectroscopy and heat-flow measurements as well as multivariate analyses are performed, apparently for the first time, to determine heats of reaction for single and parallel reactions. Two different vibrational spectroscopy techniques, namely Raman and FTIR spectroscopy, are used in conjunction with flow-through TAM III microcalorimetry. With respect to the spectroscopic analysis, the reaction spectra are first analyzed to determine the pure-component spectra and the corresponding concentrations without recourse to external calibration. With respect to the calorimetric analysis, a soft modeling approach is employed to determine the heats of reaction without recourse to any conventional kinetic models. This combined approach is implemented to determine the extents of reaction as well as the corresponding heats of reaction at 298.15 K and 0.1 MPa for a) the hydrolysis of acetic anhydride (single reaction) and b) the hydrolysis of methyl paraben and ethyl paraben in alkaline solution (both single and parallel reactions). In the latter case, the heat-flow contributions from the two simultaneous reactions are successfully decoupled. Taken together, these results demonstrate proof of concept for the present approach. The newly developed methodology appears to be quite general and particularly useful for investigating complex reaction systems. This is particularly true for multiple simultaneous reactions and reactions where the detailed kinetic expressions are not available, or cannot be easily determined. The use of extents of reaction is also very helpful where there is high variability in reaction rates

  17. First trial postural reactions to unexpected balance disturbances: a comparison with the acoustic startle reaction.

    Science.gov (United States)

    Oude Nijhuis, Lars B; Allum, John H J; Valls-Solé, Josep; Overeem, Sebastiaan; Bloem, Bastiaan R

    2010-11-01

    Unexpected support-surface movements delivered during stance elicit "first trial" postural reactions, which are larger and cause greater instability compared with habituated responses. The nature of this first trial reaction remains unknown. We hypothesized that first trial postural reactions consist of a generalized startle reaction, with a similar muscle synergy as the acoustic startle response, combined with an automatic postural reaction. Therefore we compared acoustic startle responses to first trial postural reactions. Eight healthy subjects stood on a support surface that unexpectedly rotated backwards 10 times, followed by 10 startling acoustic stimuli, or vice versa. Outcome measures included full body kinematics and surface EMG from muscles involved in startle reactions or postural control. Postural perturbations and startling acoustic stimuli both elicited a clear first trial reaction, as reflected by larger kinematic and EMG responses. The ensuing habituation rate to repeated identical stimuli was comparable for neck and trunk muscles in both conditions. Onset latencies in neck muscles occurred significantly later for first trial perturbations compared with startle responses, but earlier in trunk muscles. Our results show that platform tilting initially induces reactions larger than needed to maintain equilibrium. For neck and trunk muscles, these first trial postural reactions resembled acoustic startle reflexes. First trial postural reactions may be triggered by interaction of afferent volleys formed by somatosensory and vestibular inputs. Acoustic startle reactions may also be partially triggered by vestibular inputs. Similar muscle activation driven by vestibular inputs may be the common element of first trial postural responses and acoustic startle reactions.

  18. Preparation and Reactions of Octasilsesquioxanes

    Institute of Scientific and Technical Information of China (English)

    Liu Ling-Kang

    2004-01-01

    Because of the length scales involved, nanocomposite materials incorporate extensive interracial interactions that can result in non-linear changes in the composite property. Chemists often start from polymerizable inorganic and organic constituents in the molecule to build organic/inorganic hybrids that combine advantageous properties of disparate components.Silsesquioxanes (RSiO1.5)n, derived from e.g. RSiCl3 or RSi(OEt)3 by hydrolysis/condensation in a sol-gel process, are a class of silicate framework where each Si-atom is linked covalently to an organic radical R that chemically modifies the silicates. In addition to incompletely condensed silsesquioxanes is the completely condensed octasilsesquioxane. These octameric silsesquioxanes are in transition between small molecules and macroscopic materials with skeletal frameworks found in crystalline forms of silica and zeolites. SisO12(CH=CH2)8 1 has a cubic silica like core and 8 olefin functionalities as known for a long time yet with very few reactivity reports. The acidic hydrolytic polycondensation of (vinyl)Si(OEt)3 in the literature, leading to only less than 20% of 1,also suggests a large room for improvement. We have found that the H NMR spectra of mixtures containing 1 and either the Schrock's catalyst or the Grubbs' catalyst never exhibit vinylic 1H peaks attributable to the formation of products from self-metathesis. With a Pt/C catalyst, the H-Si bond of HSiMe2Cl adds to the vinylic double bond of 1, forming 2 that reacts with sufficient CH2=CHCH2OH to give 3. Upon treatment of the Grubbs' catalyst, a ring-closing metathesis occurs on the surface of the cubic Si8O12 framework. The results exhibit a strong proximity effect with which 3 transforms itself to 4. Alternatively 5 has been prepared.The Gmbbs' catalyst allows 5 to isomerize from Z- to E-configuration to produce 4 independentiy, thus demonstrating the ring-closing metathesis reactions of densely populated terminal olefins on Si8O12 surface.

  19. Elements from chlorine to calcium nuclear reactions

    CERN Document Server

    Kunz, Wunibald

    1968-01-01

    Nuclear Tables: Part II Nuclear Reactions, Volume 3: The Elements from Chlorine to Calcium contains tabulations of the nuclear reaction values of elements chlorine, argon, potassium, and calcium. These tabulations provide the calculated Q-values of the elements and their isotopes. This book will be of value to general chemistry researchers.

  20. Resonances and the thermonuclear reaction rate

    CERN Document Server

    Hussein, M S; Sargeant, A J; Pato, M P

    2003-01-01

    We present an approximate analytic expression for thermonuclear reaction rate of charged particles when the cross section contains a single narrow or wide resonance described by a Breit-Wigner shape. The resulting expression is uniformly valid as the effective energy and resonance energy coalesce. We use our expressions to calculate the reaction rate for $^{12}$C(p,$\\gamma$)$^{13}$N.

  1. Solvent effect in the Walden inversion reactions

    Science.gov (United States)

    Jaume, J.; Lluch, J. M.; Oliva, A.; Bertrán, J.

    1984-04-01

    The solvent effect on the fluoride exchange reaction has been studied by means of ab initio calculations using the 3-21G basis set. It is shown that the motion of the solvent molecules is an important part of the reaction coordinate.

  2. Glutathione conjugation as a bioactivation reaction

    NARCIS (Netherlands)

    Bladeren, P.J. van

    2000-01-01

    In general, glutathione conjugation is regarded as a detoxication reaction. However, depending on the properties of the substrate, bioactivation is also possible. Four types of activation reaction have been recognized: direct-acting compounds, conjugates that are activated through cysteine conjugate

  3. Organic Reaction Mechanisms at A-Level.

    Science.gov (United States)

    Norman, R. O. C.; Waddington, D. J.

    1979-01-01

    Advocates teaching of organic reaction mechanisms through the methods which are used in elucidating them. This also provides a useful way of illustrating the theories and methods of physical chemistry. Describes an approach to teaching three reaction mechanisms: substitution in alkanes; addition to alkenes; and ester hydrolysis. (Author/GA)

  4. Heuristics-Guided Exploration of Reaction Mechanisms.

    Science.gov (United States)

    Bergeler, Maike; Simm, Gregor N; Proppe, Jonny; Reiher, Markus

    2015-12-08

    For the investigation of chemical reaction networks, the efficient and accurate determination of all relevant intermediates and elementary reactions is mandatory. The complexity of such a network may grow rapidly, in particular if reactive species are involved that might cause a myriad of side reactions. Without automation, a complete investigation of complex reaction mechanisms is tedious and possibly unfeasible. Therefore, only the expected dominant reaction paths of a chemical reaction network (e.g., a catalytic cycle or an enzymatic cascade) are usually explored in practice. Here, we present a computational protocol that constructs such networks in a parallelized and automated manner. Molecular structures of reactive complexes are generated based on heuristic rules derived from conceptual electronic-structure theory and subsequently optimized by quantum-chemical methods to produce stable intermediates of an emerging reaction network. Pairs of intermediates in this network that might be related by an elementary reaction according to some structural similarity measure are then automatically detected and subjected to an automated search for the connecting transition state. The results are visualized as an automatically generated network graph, from which a comprehensive picture of the mechanism of a complex chemical process can be obtained that greatly facilitates the analysis of the whole network. We apply our protocol to the Schrock dinitrogen-fixation catalyst to study alternative pathways of catalytic ammonia production.

  5. Glutathione conjugation as a bioactivation reaction

    NARCIS (Netherlands)

    Bladeren, P.J. van

    2000-01-01

    In general, glutathione conjugation is regarded as a detoxication reaction. However, depending on the properties of the substrate, bioactivation is also possible. Four types of activation reaction have been recognized: direct-acting compounds, conjugates that are activated through cysteine conjugate

  6. Strategies for Innovation in Multicomponent Reaction Design

    OpenAIRE

    Ganem, Bruce

    2009-01-01

    By generating structural complexity in a single step from three or more reactants, multicomponent reactions (MCRs) make it possible to synthesize target compounds with greater efficiency and atom economy. The history of such reactions can be traced to the mid-nineteenth century when Strecker first produced α-aminonitriles from the condensation of aldehydes with ammonia and hydrogen cyanide.

  7. Detecting radiation reaction at moderate laser intensities.

    Science.gov (United States)

    Heinzl, Thomas; Harvey, Chris; Ilderton, Anton; Marklund, Mattias; Bulanov, Stepan S; Rykovanov, Sergey; Schroeder, Carl B; Esarey, Eric; Leemans, Wim P

    2015-02-01

    We propose a new method of detecting radiation reaction effects in the motion of particles subjected to laser pulses of moderate intensity and long duration. The effect becomes sizable for particles that gain almost no energy through the interaction with the laser pulse. Hence, there are regions of parameter space in which radiation reaction is actually the dominant influence on charged particle motion.

  8. Reactions the private life of atoms

    CERN Document Server

    Atkins, Peter

    2011-01-01

    Through an innovative, closely integrated design of images and text, and his characteristically clear, precise, and economical exposition, Peter Atkins explains the processes involved in chemical reactions. He begins by introducing a 'tool kit' of basic reactions, such as precipitation, corrosion, and catalysis, and concludes by showing how these building blocks are brought together in more complex processes such as photosynthesis.

  9. Reliability of a Shuttle reaction timer

    Science.gov (United States)

    Hays, Russell D.; Mazzocca, Augustus D.; Rashid, Michael; Siconolfi, Steven F.

    1992-01-01

    Reaction, movement, and task times refer to the times needed to initially respond to a stimulus, make the specific movement, and complete the entire task. This study evaluated the reliability of a simple reaction timer designed to mimic a Space Shuttle task (turning on an overhead switch).

  10. Ambulatory Measurement of Ground Reaction Forces

    NARCIS (Netherlands)

    Veltink, Petrus H.; Liedtke, C.B.; Droog, Adriaan

    2004-01-01

    The measurement of ground reaction forces is important in the biomechanical analysis of gait and other motor activities. It is the purpose of this study to show the feasibility of ambulatory measurement of ground reaction forces using two six degrees of freedom sensors mounted under the shoe. One

  11. Femtosecond laser control of chemical reactions

    CSIR Research Space (South Africa)

    Du Plessis, A

    2010-08-31

    Full Text Available Femtosecond laser control of chemical reactions is made possible through the use of pulse-shaping techniques coupled to a learning algorithm feedback loop – teaching the laser pulse to control the chemical reaction. This can result in controllable...

  12. Entropy Generation in a Chemical Reaction

    Science.gov (United States)

    Miranda, E. N.

    2010-01-01

    Entropy generation in a chemical reaction is analysed without using the general formalism of non-equilibrium thermodynamics at a level adequate for advanced undergraduates. In a first approach to the problem, the phenomenological kinetic equation of an elementary first-order reaction is used to show that entropy production is always positive. A…

  13. Pinacol Coupling Reactions Catalyzed by Active Zinc

    Institute of Scientific and Technical Information of China (English)

    Hui ZHAO; Wei DENG; Qing Xiang GUO

    2005-01-01

    Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition, the results indicated that the zinc activity has a direct relation to the coupling reactivity compared to untreated zinc or other general active zinc.

  14. Liquid drop effects in subbarrier transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.J.

    1990-08-01

    Reaction products from a multitude of binary channels are observed to emerge at large c.m. angles at subbarrier energies for the {sup 50}Ti {plus} {sup 93}Nb system. The energy spectra of these products and the distance where they first emerge indicate that these reaction products result from the neck which is formed outside the Coulomb barrier. 9 refs., 5 figs.

  15. Reaction between drug substances and pharmaceutical excipients

    DEFF Research Database (Denmark)

    Larsen, Jesper; Cornett, Claus; Jaroszewski, Jerzy Witold

    2009-01-01

    The reactivity of citric acid towards drug substances in the solid state was examined using the beta-blocker carvedilol as a model compound. The reaction mixtures were analysed by LC-MS, the reaction products were isolated by preparative HPLC, and the structures were elucidated by microprobe NMR...

  16. Analytical Study of Thermonuclear Reaction Probability Integrals

    CERN Document Server

    Chaudhry, M A; Mathai, A M

    2000-01-01

    An analytic study of the reaction probability integrals corresponding to the various forms of the slowly varying cross-section factor $S(E)$ is attempted. Exact expressions for reaction probability integrals are expressed in terms of the extended gamma functions.

  17. Substitution reactions at boron atoms in metallacarboranes

    Energy Technology Data Exchange (ETDEWEB)

    Bregadze, Vladimir I; Timofeev, Sergei V; Sivaev, Igor B; Lobanova, Irina A [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation)

    2004-05-31

    Data on substitution reactions at boron atoms in 10-12-vertex metallacarboranes, which are of fundamental and applied significance, are generalised. The possible mechanisms of substitution reactions and the influence of the metal fragment on substitution positions in the polyhedron are discussed.

  18. Hydrazine in the Ugi Tetrazole Reaction

    NARCIS (Netherlands)

    Patil, Pravin; Zhang, Ji; Kurpiewska, Katarzyna; Kalinowska-Tłuścik, Justyna; Dömling, Alexander

    2016-01-01

    We describe the hitherto unknown use of N-Boc-protected hydrazine in the Ugi tetrazole reaction to access a library of highly substituted 5-(hydrazinomethyl)-1-methyl-1H-tetrazoles. The reaction is very versatile and good to high yielding. A one-pot, two-step procedure is given.

  19. A Full Disturbance Model for Reaction Wheels

    NARCIS (Netherlands)

    Le, M.P.; Ellenbroek, Marcellinus Hermannus Maria; Seiler, R; van Put, P.; Cottaar, E.J.E.

    2014-01-01

    Reaction wheels are rotating devices used for the attitude control of spacecraft. However, reaction wheels also generate undesired disturbances in the form of vibrations, which may have an adverse effect on the pointing accuracy and stability of spacecraft (optical) payloads. A disturbance model for

  20. Reaction mechanisms: Stripping down SN2

    Science.gov (United States)

    Orr-Ewing, Andrew J.

    2012-07-01

    The mechanism of the SN2 reaction is fundamental to understanding and controlling the stereochemistry of organic reactions, but surrounding solvent molecules may complicate the textbook picture. Micro-solvation studies have now explored the stereochemical consequences of the presence of one or two solvent molecules.

  1. Heavy ion transfer reactions: Status and perspectives

    Indian Academy of Sciences (India)

    L Corradi

    2010-07-01

    With the large solid angle magnetic spectrometer (PRISMA) coupled to the -array (CLARA), extensive investigations of nuclear structure and reaction dynamics have been carried out. In the present paper aspects of these studies will be presented, focussing more closely on the reaction mechanism, in particular on the properties of quasielastic and deep inelastic processes and on measurements at energies far below the Coulomb barrier.

  2. Psychological factors that predict reaction to abortion.

    Science.gov (United States)

    Moseley, D T; Follingstad, D R; Harley, H; Heckel, R V

    1981-04-01

    Investigated demographic and psychological factors related to positive or negative reactions to legal abortions performed during the first trimester of pregnancy in 62 females in an urban southern community. Results suggest that the social context and the degree of support from a series of significant persons rather than demographic variables were most predictive of a positive reaction.

  3. Catalytic Hydrogenation Reaction of Naringin-Chalcone. Study of the Electrochemical Reaction

    Directory of Open Access Journals (Sweden)

    B. A. López de Mishima

    2000-03-01

    Full Text Available The electrocatalytic hydrogenation reaction of naringin derivated chalcone is studied. The reaction is carried out with different catalysts in order to compare with the classic catalytic hydrogenation.

  4. Snake antivenoms: adverse reactions and production technology

    Directory of Open Access Journals (Sweden)

    VM Morais

    2009-01-01

    Full Text Available Antivenoms have been widely used for more than a century for treating snakebites and other accidents with poisonous animals. Despite their efficacy, the use of heterologous antivenoms involves the possibility of adverse reactions due to activation of the immune system. In this paper, alternatives for antivenom production already in use were evaluated in light of their ability to minimize the occurrence of adverse reactions. These effects were classified according to their molecular mechanism as: anaphylactic reactions mediated by IgE, anaphylactoid reactions caused by complement system activation, and pyrogenic reactions produced mainly by the presence of endotoxins in the final product. In the future, antivenoms may be replaced by humanized antibodies, specific neutralizing compounds or vaccination. Meanwhile, improvements in antivenom quality will be focused on the obtainment of a more purified and specific product in compliance with good manufacturing practices and at an affordable cost.

  5. Low energy ion-molecule reactions

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, J.M. [Univ. of Rochester, NY (United States)

    1993-12-01

    This project is concerned with elucidating the dynamics of elementary ion-molecule reactions at collision energies near and below 1 eV. From measurements of the angular and energy distributions of the reaction products, one can infer intimathe details about the nature of collisions leading to chemical reaction, the geometries and lifetimes of intermediate complexes that govern the reaction dynamics, and the collision energy dependence of these dynamical features. The author employs crossed-beam low energy mass spectrometry technology developed over the last several years, with the focus of current research on proton transfer and hydrogen atom transfer reactions of te O{sup {minus}} ion with species such as HF, H{sub 2}O, and NH{sub 3}.

  6. A new look at the chemical reaction

    Directory of Open Access Journals (Sweden)

    Johannes A.A.W. Elemans

    2009-07-01

    Full Text Available At the heart of chemistry has always been the chemical reaction, and numerous analytical tools, such as NMR, UV-vis spectroscopy and mass spectrometry, are commonly used to elucidate reaction mechanisms. These conventional techniques have, however, an important limitation: they measure ensembles of millions of molecules at the same time and give only an average picture of a reaction mechanism, which might be incomplete and misleading because certain molecules might react whilst others are inactive. It is for this reason that during the past decade the interest is increasingly focusing on studying chemical reactions at the level of single molecules, and the stormy development of methods that allow such single molecule investigations, in particular Scanning Probe Microscopy, makes totally new insights in reaction mechanisms possible.

  7. Acceleration of Organic Reactions Using Microwave

    Institute of Scientific and Technical Information of China (English)

    Lu Ta-Jung

    2004-01-01

    The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted direct amide formation from carboxylic acid and amine, the hydrolysis of biopolymers, and nucleophilic aromatic substitution reaction. The reactions carried out under microwave irradiation, in general, required considerably less reaction time and afforded the desired products in higher yields than those under classical conditions. In all the cases we have studied, the procedures are simplified, the purity of the products are higher, and the cost of reaction is greatly reduced employing microwave.

  8. The reaction index and positivity ratio revisited

    DEFF Research Database (Denmark)

    Andersen, Klaus Ejner; Andersen, Flemming

    2008-01-01

    BACKGROUND AND OBJECTIVES: Assessing the quality of patch test preparations continues to be a challenge. 2 parameters, the reaction index (RI) and positivity ratio (PR), have been proposed as quality indicators by the Information Network of Departments of Dermatology (IVDK). The value of these st......BACKGROUND AND OBJECTIVES: Assessing the quality of patch test preparations continues to be a challenge. 2 parameters, the reaction index (RI) and positivity ratio (PR), have been proposed as quality indicators by the Information Network of Departments of Dermatology (IVDK). The value...... of the IVDK and our department. Calculation of RI's and PR's for patch test allergens is of limited value as a measure of quality of the patch test materials, because it predominantly reflects differences in scoring and reading of patch test reactions. Further, questionable reactions (+?) may be clinically...... relevant and very important for the individual patient. Focus on standardization of patch test materials, patch test technique, and reading of patch test reactions is mandatory....

  9. Reaction mechanism of -acylhydroxamate with cysteine proteases

    Indian Academy of Sciences (India)

    R Shankar; P Kolandaivel

    2007-09-01

    The gas-phase reaction mechanism of -acylhydroxamate with cysteine proteases has been investigated using ab initio and density functional theory. On the irreversible process, after breakdown of tetrahedral intermediate (INT1), small 1-2 anionotropic has been formed and rearranged to give stable by-products sulfenamide (P1) and thiocarbamate (P2) with considerable energy loss. While, on the reversible part of this reaction mechanism, intermediate (INT2) breaks down on oxidation, to form a stable product (P3). Topological and AIM analyses have been performed for hydrogen bonded complex in this reaction profile. Intrinsic reaction coordinates [IRC, minimum-energy path (MEP)] calculation connects the transition state between R-INT1, INT1-P1 and INT1-P2. The products P1, P2 and P3 are energetically more stable than the reactant and hence the reaction enthalpy is found to be exothermic.

  10. Diffusion and reaction in crowded environments

    Energy Technology Data Exchange (ETDEWEB)

    EcheverIa, Carlos [Laboratorio de Fisica Aplicada y Computacional, Departamento de Matematica y Fisica, Universidad Nacional Experimental del Tachira, San Cristobal 5001 (Venezuela); Tucci, Kay [Centro de Fisica Fundamental, Universidad de Los Andes, Merida 5101 (Venezuela); Kapral, Raymond [Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, ON, M5S 3H6 (Canada)

    2007-02-14

    The effects of molecular crowding on small molecule diffusion and chemical reaction rate coefficients are investigated. The systems considered comprise a random distribution of stationary spherical obstacles occupying a volume fraction {phi} of the system and a large number of small molecules whose dynamics are followed. Chemical reactions are studied in such crowded systems where, in addition to the obstacles, a large reactive sphere C is present that catalyses the reaction A+C {yields} B+C. Using a mesoscopic description of the dynamics employing multiparticle collisions among the small molecules, the {phi} dependence of the diffusion and reaction rate coefficients is computed. Both the diffusion and reaction rate coefficients decrease with increase of the obstacle volume fraction as expected but variations of these quantities with {phi} are not predicted by simple models of the dynamics.

  11. The Pozzolanic reaction of silica fume

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2012-01-01

    Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the ...... of activation of the pozzolanic reaction of silica fume is estimated. The results show that the pozzolanic reaction of silica fume has notable differences from Portland cement hydration.......Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone....... In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy...

  12. Stabilized enzymes in continuous gas phase reactions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fangxiao; LeJeune, K.; Yang, Zhen [Univ. of Pittsburgh, PA (United States)] [and others

    1995-12-01

    We are assessing the utility of enzymes to catalyze reactions in a continuous gas phase reactor. First, alcohol dehydrogenase has been used to oxidize an unsaturated alcohol, 3-methyl-2-buten-1-ol (UOL), to the corresponding unsaturated aldehyde, 3-methyl-2-butenal (UAL). Cofactor NAD{sup +} was regenerated by concomitant acetone reduction to isopropyl alcohol. Second, organophosphorus hydrolase (OPH) has been used to hydrolyze pesticide vapors. In order to control enzyme hydration level, enzyme water adsorption isotherms at different temperature have been studied. Huttig`s isotherm model has been found suitable to describe adsorption behavior. The influence of enzyme hydration level, enzyme loading on glass beads, reaction temperature and flow rate on enzymatic reaction rate and biocatalyst stability were investigated. Reaction kinetics were studied and a kinetic model was proposed. We will also report our attempts to further stabilize enzymes for use in gas reactions by incorporating them into polymer matrices.

  13. Mechanisms of inorganic and organometallic reactions

    CERN Document Server

    The purpose of this series is to provide a continuing critical review of the literature concerned with mechanistic aspects of inorganic and organo­ metallic reactions in solution, with coverage being complete in each volume. The papers discussed are selected on the basis of relevance to the elucidation of reaction mechanisms and many include results of a nonkinetic nature when useful mechanistic information can be deduced. The period of literature covered by this volume is July 1982 through December 1983, and in some instances papers not available for inclusion in the previous volume are also included. Numerical results are usually reported in the units used by the original authors, except where data from different papers are com­ pared and conversion to common units is necessary. As in previous volumes material included covers the major areas of redox processes, reactions of the nonmetallic elements, reaction of inert and labile metal complexes and the reactions of organometallic compounds. While m...

  14. Tandem Catalysis Utilizing Olefin Metathesis Reactions.

    Science.gov (United States)

    Zieliński, Grzegorz K; Grela, Karol

    2016-07-01

    Since olefin metathesis transformation has become a favored synthetic tool in organic synthesis, more and more distinct non-metathetical reactions of alkylidene ruthenium complexes have been developed. Depending on the conditions applied, the same olefin metathesis catalysts can efficiently promote isomerization reactions, hydrogenation of C=C double bonds, oxidation reactions, and many others. Importantly, these transformations can be carried out in tandem with olefin metathesis reactions. Through addition of one portion of a catalyst, a tandem process provides structurally advanced products from relatively simple substrates without the need for isolation of the intermediates. These aspects not only make tandem catalysis very attractive from a practical point of view, but also open new avenues in (retro)synthetic planning. However, in the literature, the term "tandem process" is sometimes used improperly to describe other types of multi-reaction sequences. In this Concept, a number of examples of tandem catalysis involving olefin metathesis are discussed with an emphasis on their synthetic value.

  15. Selective immediate hypersensitivity reactions to NSAIDs.

    Science.gov (United States)

    Canto, Maria Gabriela; Andreu, Isabel; Fernandez, Javier; Blanca, Miguel

    2009-08-01

    Selective immediate reactions to NSAIDs imply that patients develop a urticarial/anaphylactic response to a single drug with good tolerance to other compounds. No systematic review of these reactions has yet been made. With the increase in consumption of NSAIDs, these have become one of the most common drugs inducing hypersensitivity reactions. Although cross-intolerance reactions are the most common, a significant proportion is selective responses. As specific IgE antibodies are not always found, there is only indirect evidence supporting an IgE-mediated mechanism in selective NSAID reactors. Selective immediate reactions to NSAIDs must be considered when a patient develops urticaria or anaphylaxis after intake of one drug with good tolerance to drugs from other groups or even a drug from the same group with a slightly different chemical structure. Further research is required to identify the antigenic determinant structures recognized.

  16. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA.

  17. Multilayer Network Analysis of Nuclear Reactions

    Science.gov (United States)

    Zhu, Liang; Ma, Yu-Gang; Chen, Qu; Han, Ding-Ding

    2016-08-01

    The nuclear reaction network is usually studied via precise calculation of differential equation sets, and much research interest has been focused on the characteristics of nuclides, such as half-life and size limit. In this paper, however, we adopt the methods from both multilayer and reaction networks, and obtain a distinctive view by mapping all the nuclear reactions in JINA REACLIB database into a directed network with 4 layers: neutron, proton, 4He and the remainder. The layer names correspond to reaction types decided by the currency particles consumed. This combined approach reveals that, in the remainder layer, the β-stability has high correlation with node degree difference and overlapping coefficient. Moreover, when reaction rates are considered as node strength, we find that, at lower temperatures, nuclide half-life scales reciprocally with its out-strength. The connection between physical properties and topological characteristics may help to explore the boundary of the nuclide chart.

  18. SYSTEMIC TOXIC REACTIONS TO LOCAL ANESTHETICS

    Science.gov (United States)

    Moore, Daniel C.; Green, John

    1956-01-01

    The topical use of anesthetic agents involves an element of risk. Systemic toxic reactions are rare, but they do occur and may result in death. When a reaction occurs from a topical application, it usually progresses rapidly to respiratory and cardiovascular collapse, and thus therapy must be instituted with more haste to avoid deaths. Fatal systemic toxic reactions from topically administered anesthetic drugs are, in effect, usually not due to well informed use of the drug but to misuse owing to less than complete understanding of absorption. Emphasis is placed on the causes, prophylaxis and treatment of severe systemic toxic reactions which follow the topical application of local anesthetic drugs. If systemic toxic reactions resulting from a safe dose of a local anesthetic agent are correctly treated, there will usually follow an uneventful recovery rather than a catastrophe. PMID:13343009

  19. Multilayer network analysis of nuclear reactions

    CERN Document Server

    Zhu, Liang; Chen, Qu; Han, Ding-Ding

    2016-01-01

    The nuclear reaction network is usually studied via precise calculation of differential equation sets, and much research interest has been focused on the characteristics of nuclides, such as half-life and size limit. In this paper, however, we adopt the methods from both multilayer and reaction networks, and obtain a distinctive view by mapping all the nuclear reactions in JINA REACLIB database into a directed network with 4 layers: neutron, proton, $^4$He and the remainder. The layer names correspond to reaction types decided by the currency particles consumed. This combined approach reveals that, in the remainder layer, the $\\beta$-stability has high correlation with node degree difference and overlapping coefficient. Moreover, when reaction rates are considered as node strength, we find that, at lower temperatures, nuclide half-life scales reciprocally with its out-strength. The connection between physical properties and topological characteristics may help to explore the boundary of the nuclide chart.

  20. A Reaction of Aspirin with Ferrous Gluconate.

    Science.gov (United States)

    Zhang, Jian

    2015-12-01

    A color reaction of aspirin with ferrous gluconate was studied by UV-Vis spectrophotometry and HPLC-MS. It was found that the UV-Vis spectra of the two drugs were different before and after they were mixed in water at about 0.3 M (diluted by >20 times for analysis), indicating that a complexation reaction took place. The drug-iron complex dissociated when the reacting solution was diluted by 400 times. The by-products of the reaction identified by HPLC-MS were salicylic acid, acetylated gluconic acid, salicylate-gluconic acid conjugate, and an oxidized product of salicylic acid that was complexed with iron with a molecular weight of 212. This reaction may be used as an important consideration to optimize the dosing regime of the two drugs and to help explain some pharmacological reactions between aspirin and biomolecules.

  1. A Reaction-Based River/Stream Water Quality Model: Reaction Network Decomposition and Model Application

    OpenAIRE

    2012-01-01

    This paper describes details of an automatic matrix decomposition approach for a reaction-based stream water quality model. The method yields a set of equilibrium equations, a set of kinetic-variable transport equations involving kinetic reactions only, and a set of component transport equations involving no reactions. Partial decomposition of the system of water quality constituent transport equations is performed via Gauss-Jordan column reduction of the reaction network by pivoting on equil...

  2. First trial postural reactions to unexpected balance disturbances: a comparison with the acoustic startle reaction.

    NARCIS (Netherlands)

    Oude Nijhuis, L.B.; Allum, J.H.J.; Valls-Sole, J.; Overeem, S.; Bloem, B.R.

    2010-01-01

    Unexpected support-surface movements delivered during stance elicit "first trial" postural reactions, which are larger and cause greater instability compared with habituated responses. The nature of this first trial reaction remains unknown. We hypothesized that first trial postural reactions consis

  3. A Green Multicomponent Reaction for the Organic Chemistry Laboratory: The Aqueous Passerini Reaction

    Science.gov (United States)

    Hooper, Matthew M.; DeBoef, Brenton

    2009-01-01

    Water is the ideal green solvent for organic reactions. However, most organic molecules are insoluble in it. Herein, we report a laboratory module that takes advantage of this property. The Passerini reaction, a three-component coupling involving an isocyanide, aldehyde, and carboxylic acid, typically requires [similar to] 24 h reaction times in…

  4. Effect of Reaction Developing Training on Audio-Visual Feet Reaction Time in Wrestlers

    Science.gov (United States)

    Kaya, Mustafa

    2016-01-01

    Reaction time is one of the most determinative elements for a successful sports performance. The purpose of this study was to investigate the effect of 12-week feet reaction developing trainings upon feet reaction time of females at 11-13 age interval. Volunteer sportsmen between 11 and 13 age interval who were active in Tokat Provincial…

  5. The quantum normal form approach to reactive scattering : The cumulative reaction probability for collinear exchange reactions

    NARCIS (Netherlands)

    Goussev, Arseni; Schubert, Roman; Waalkens, Holger; Wiggins, Stephen

    2009-01-01

    The quantum normal form approach to quantum transition state theory is used to compute the cumulative reaction probability for collinear exchange reactions. It is shown that for heavy-atom systems such as the nitrogen-exchange reaction, the quantum normal form approach gives excellent results and

  6. Autocatalysis-driven clock reaction II: kinetics of the pentathionate-periodate reaction.

    Science.gov (United States)

    Xu, Li; Horváth, Attila K

    2014-10-23

    The pentathionate-periodate reaction has been investigated by spectrophotometrically monitoring the total amount of iodine evolved in the presence of phosphoric acid/dihydrogen phosphate buffer at 468 nm. The majority of the main characteristics of the title system is very reminiscent of that found recently in the pentathionate-iodate reaction, a system that led us to classify generally the clock reactions. Along with the pentathionate-iodate reaction the title system is proposed to belong to the autocatalysis-driven clock reactions as well. The kinetic model of the pentathionate-iodate system published recently was implemented by the necessary reactions of periodate to compose a 24-step kinetic model in which the mechanisms of the pentathionate-iodine, pentathionate-iodate, bisulfite-periodate, bisulfite-iodate, iodide-periodate, and the well-known Dushman reactions are combined. A thorough analysis revealed that the direct pentathionate-periodate reaction plays a role only to produce iodide ion via a finite sequence of reactions, and once its concentration reaches a certain level, the reaction is almost exclusively governed by the pentathionate-iodine, the iodide-periodate, and the Dushman reactions. As expected strong catalytic effect of the buffer composition is also found that can readily be explained by its well-known catalytic influence on the Dushman reaction.

  7. Synthesis and Reactions of Acenaphthenequinones-Part-2. The Reactions of Acenaphthenequinones

    Directory of Open Access Journals (Sweden)

    Mahmoud Shoukry

    2002-02-01

    Full Text Available The reactions of acenaphthenequinone and its derivatives with different nucleophiles, organic and inorganic reagents are reviewed. This survey also covers their oxidation and reduction reactions, in addition to many known reactions such as Friedel Crafts, Diels-Alder, bromination and thiolation.

  8. A Green Multicomponent Reaction for the Organic Chemistry Laboratory: The Aqueous Passerini Reaction

    Science.gov (United States)

    Hooper, Matthew M.; DeBoef, Brenton

    2009-01-01

    Water is the ideal green solvent for organic reactions. However, most organic molecules are insoluble in it. Herein, we report a laboratory module that takes advantage of this property. The Passerini reaction, a three-component coupling involving an isocyanide, aldehyde, and carboxylic acid, typically requires [similar to] 24 h reaction times in…

  9. The oxygen evolution reaction on cobalt Part I. Reaction order experiments and impedance measurements

    NARCIS (Netherlands)

    Kobussen, A.G.C.; Willems, H.; Wit, J.H.W. de; Broers, G.H.J.

    1984-01-01

    It was found that the oxygen evolution reaction on cobalt in concentrated KOH solutions can be described differently for low and high overpotentials. In the overpotential range from 150 to 280 mV, the reaction has a Tafel slope of approximately 40 mV and a reaction order with respect to the KOH acti

  10. Links between potential energy structures and quantum cumulative reaction probabilities of double proton transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Horsten, H.F. von [Institut fuer Physikalische Chemie, Christian-Albrechts-Universitaet, Olshausenstrasse 40, 24098 Kiel (Germany); Hartke, B. [Institut fuer Physikalische Chemie, Christian-Albrechts-Universitaet, Olshausenstrasse 40, 24098 Kiel (Germany)], E-mail: hartke@phc.uni-kiel.de

    2007-09-25

    Double proton transfer reactions of pyrazole-guanidine species exhibit unusual energy profiles of a plateau form, different from the standard single and double barrier shapes. We have demonstrated earlier that this leads to a characteristically different quantum dynamical behavior of plateau reactions, when measured appropriately. Here we show that these differences also carry over to traditional measures of reaction probability.

  11. Understanding Active Metal Reaction Kinetis with Cu-Mg Replacement Reaction

    Indian Academy of Sciences (India)

    Ilhami Ceyhun; Zafer Karagolge

    2017-02-01

    Metal substitution reactions are simple redox reactions. Thesereactions demonstrate the relative activity and the electrochemicalseries of metals. In particular, the purpose of thisstudy is to help students comprehend the displacement reactionamong, Mg metal and solutions containing Cu$^{+2}$, Ni$^{+2}$,Pb$^{+2}$, Cd$^{+2}$, Co$^{+2}$. This study is an important experiment towardsunderstanding reaction kinetics.

  12. Minisatellite Attitude Guidance Using Reaction Wheels

    Directory of Open Access Journals (Sweden)

    Ion STROE

    2015-06-01

    Full Text Available In a previous paper [2], the active torques needed for the minisatellite attitude guidance from one fixed attitude posture to another fixed attitude posture were determined using an inverse dynamics method. But when considering reaction/momentum wheels, instead of this active torques computation, the purpose is to compute the angular velocities of the three reaction wheels which ensure the minisatellite to rotate from the initial to the final attitude. This paper presents this computation of reaction wheels angular velocities using a similar inverse dynamics method based on inverting Euler’s equations of motion for a rigid body with one fixed point, written in the framework of the x-y-z sequence of rotations parameterization. For the particular case A=B not equal C of an axisymmetric minisatellite, the two computations are compared: the active torques computation versus the computation of reaction wheels angular velocities ̇x , ̇y and ̇z. An interesting observation comes out from this numerical study: if the three reaction wheels are identical (with Iw the moment of inertia of one reaction wheel with respect to its central axis, then the evolutions in time of the products between Iw and the derivatives of the reaction wheels angular velocities, i.e. ̇ , ̇ and ̇ remain the same and do not depend on the moment of inertia Iw.

  13. Kiss-induced severe anaphylactic reactions

    Directory of Open Access Journals (Sweden)

    Atanasković-Marković Marina

    2010-01-01

    Full Text Available Introduction. Ingestion is the principal route for food allergens to trigger allergic reaction in atopic persons. However, in some highly sensitive patients severe symptoms may develop upon skin contact and by inhalation. The clinical spectrum ranges from mild facial urticaria and angioedema to life-threatening anaphylactic reactions. Outline of Cases. We describe cases of severe anaphylactic reactions by skin contact, induced by kissing in five children with prior history of severe anaphylaxis caused by food ingestion. These cases were found to have the medical history of IgE mediated food allergy, a very high total and specific serum IgE level and very strong family history of allergy. Conclusion. The presence of tiny particles of food on the kisser's lips was sufficient to trigger an anaphylactic reaction in sensitized children with prior history of severe allergic reaction caused by ingestion of food. Allergic reaction provoked with food allergens by skin contact can be a risk factor for generalized reactions. Therefore, extreme care has to be taken in avoiding kissing allergic children after eating foods to which they are highly allergic. Considering that kissing can be a cause of severe danger for the food allergic patient, such persons should inform their partners about the risk factor for causing their food hypersensitivity.

  14. Spontaneous Hedonic Reactions to Social Media Cues.

    Science.gov (United States)

    van Koningsbruggen, Guido M; Hartmann, Tilo; Eden, Allison; Veling, Harm

    2017-05-01

    Why is it so difficult to resist the desire to use social media? One possibility is that frequent social media users possess strong and spontaneous hedonic reactions to social media cues, which, in turn, makes it difficult to resist social media temptations. In two studies (total N = 200), we investigated less-frequent and frequent social media users' spontaneous hedonic reactions to social media cues using the Affect Misattribution Procedure-an implicit measure of affective reactions. Results demonstrated that frequent social media users showed more favorable affective reactions in response to social media (vs. control) cues, whereas less-frequent social media users' affective reactions did not differ between social media and control cues (Studies 1 and 2). Moreover, the spontaneous hedonic reactions to social media (vs. control) cues were related to self-reported cravings to use social media and partially accounted for the link between social media use and social media cravings (Study 2). These findings suggest that frequent social media users' spontaneous hedonic reactions in response to social media cues might contribute to their difficulties in resisting desires to use social media.

  15. Resonant elastic scattering, inelastic scattering and astrophysical reactions; Diffusion elastique resonante, diffusion inelastique et reactions astrophysiques

    Energy Technology Data Exchange (ETDEWEB)

    De Oliveira Santos, F. [Grand Accelerateur National d' Ions Lourds, UMR 6415, 14 - Caen (France)

    2007-07-01

    Nuclear reactions can occur at low kinetic energy. Low-energy reactions are characterized by a strong dependence on the structure of the compound nucleus. It turns out that it is possible to study the nuclear structure by measuring these reactions. In this course, three types of reactions are treated: Resonant Elastic Scattering (such as N{sup 14}(p,p)N{sup 14}), Inelastic Scattering (such as N{sup 14}(p,p')N{sup 14*}) and Astrophysical reactions (such as N{sup 14}(p,{gamma})O{sup 15}). (author)

  16. Quantum Theory of Fast Chemical Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Light, John C

    2007-07-30

    The aims of the research under this grant were to develop a theoretical understanding and predictive abiility for a variety of processes occurring in the gas phase. These included bimolecular chemical exchange reactions, photodissociation, predissociation resonances, unimolecular reactions and recombination reactions. In general we assumed a knowledge, from quantum chemistry, of the interactions of the atoms and molecular fragments involved. Our focus was primarily on the accurate (quantum) dynamics of small molecular systems. This has been important for many reactions related to combustion and atmospheric chemistry involving light atom transfer reactions and, for example, resonances in dissociation and recombination reactions. The rates of such reactions, as functions of temperature, internal states, and radiation (light), are fundamental for generating models of overall combustion processes. A number of new approaches to these problems were developed inclluding the use of discrete variable representations (DVR's) for evaluating rate constants with the flux-flux correlation approach, finite range approaches to exact quantum scattering calculations, energy selected basis representations, transition state wave packet approaches and improved semiclassical approaches. These (and others) were applied to a number of reactive systems and molecular systems of interest including (many years ago) the isotopic H + H2 exchange reactions, the H2 + OH (and H + H2O) systems, Ozone resonances, van der Waals molecule reactions, etc. A total of 7 graduate students, and 5 post-doctoral Research Associates were supported, at least in part, under this grant and seven papers were published with a total of 10 external collaborators. The majority of the 36 publications under this grant were supported entirely by DOE.

  17. ReactionMap: an efficient atom-mapping algorithm for chemical reactions.

    Science.gov (United States)

    Fooshee, David; Andronico, Alessio; Baldi, Pierre

    2013-11-25

    Large databases of chemical reactions provide new data-mining opportunities and challenges. Key challenges result from the imperfect quality of the data and the fact that many of these reactions are not properly balanced or atom-mapped. Here, we describe ReactionMap, an efficient atom-mapping algorithm. Our approach uses a combination of maximum common chemical subgraph search and minimization of an assignment cost function derived empirically from training data. We use a set of over 259,000 balanced atom-mapped reactions from the SPRESI commercial database to train the system, and we validate it on random sets of 1000 and 17,996 reactions sampled from this pool. These large test sets represent a broad range of chemical reaction types, and ReactionMap correctly maps about 99% of the atoms and about 96% of the reactions, with a mean time per mapping of 2 s. Most correctly mapped reactions are mapped with high confidence. Mapping accuracy compares favorably with ChemAxon's AutoMapper, versions 5 and 6.1, and the DREAM Web tool. These approaches correctly map 60.7%, 86.5%, and 90.3% of the reactions, respectively, on the same data set. A ReactionMap server is available on the ChemDB Web portal at http://cdb.ics.uci.edu .

  18. Type II lepra reaction: an unusual presentation.

    Science.gov (United States)

    Chauhan, S; D'Cruz, S; Mohan, H; Singh, R; Ram, J; Sachdev, A

    2006-01-27

    Ulcers with maculo-papular rash are an unusual presenting feature of leprosy. They occur as result of neuropathy, type-2 lepra reaction or Lucio's phenomenon. The hall mark of type-2 reaction is erythema nodosum. Very rarely it manifests as ulcerative skin lesions. We describe one such unusual case of a young male who presented with multiple ulcers and maculo-papular rash over the legs, chest and abdomen. In addition to this, he had fever, heart murmur, pulmonary infiltrates, neuropathy, and deranged liver function. A clinical differential diagnosis of infective endocarditis and systemic nectrozing vasculitis was made. Skin biopsy showed dense inflammation with lepra bacilli consistent with type-2 lepra reaction.

  19. REACTION CHEMISTRY RELATED TO FCC GASOLINE QUALITY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    About 80% of the gasoline pool as a whole in China for supplying the domestic market at current stage directly originates from FCC units. Obviously, FCC gasoline quality is critical for refiners to meet the nations more and more stringent gasoline specifications. FCC process is expected to produce gasoline with reduced contents of olefins, aromatics, benzene, sulfur, and, contradictorily, still with high octane number.   Catalytic cracking process involves a series of acid catalyzed reactions. Bronsted acid sites dominate the surface of the catalyst used for FCC process. All the reactions of hydrocarbons in FCC process are based on carbonium ions of penta-coordinated, or carbenium ions of tri-coordinated. The monomolecular beta scission mechanism for alkane cracking explains that the cracking of carbon-carbon bonding occurs at the beta position to the carbon atom bearing positive charge, and hence forms two small hydrocarbon molecules: one alkane molecule and one olefin molecule. The molar ratio of alkane to olefin for the primary cracking product will be 1 and it will be less than 1 if the cracking reaction proceeds.   However, it is proved that bimolecular reaction pathways exist between surface carbenium ions and the feed molecules. The products of this bimolecular disproportionation reaction could be an alkane molecule and a newly formed carbenium ion. The better understanding of the reaction chemistry of FCC process based on monomolecular pathways and bimolecular pathways should be the basis for searching approaches to the improvement of FCC gasoline quality. In the complicated reaction scheme of the FCC process, the isomerization reaction leading to the formation of iso-alkanes is obviously a target reaction, which favors both olefin reduction and octane enhancement.   The cracking of small paraffin molecules, due to its limited number of reaction pathways and products, has been used to investigate cracking mechanism. In the present work the

  20. Flows and chemical reactions in heterogeneous mixtures

    CERN Document Server

    Prud'homme, Roger

    2014-01-01

    This book - a sequel of previous publications 'Flows and Chemical Reactions' and 'Chemical Reactions in Flows and Homogeneous Mixtures' - is devoted to flows with chemical reactions in heterogeneous environments.  Heterogeneous media in this volume include interfaces and lines. They may be the site of radiation. Each type of flow is the subject of a chapter in this volume. We consider first, in Chapter 1, the question of the generation of environments biphasic individuals: dusty gas, mist, bubble flow.  Chapter 2 is devoted to the study at the mesoscopic scale: particle-fluid exchange of mom

  1. Reaction-Diffusion in the NEURON Simulator

    Directory of Open Access Journals (Sweden)

    Robert A. McDougal

    2013-11-01

    Full Text Available In order to support research on the role of cell biological principles (genomics, proteomics, signaling cascades and reaction dynamics on the dynamics of neuronal response in health and disease, NEURON has developed a Reaction-Diffusion (rxd module in Python which provides specification and simulation for these dynamics, coupled with the electrophysiological dynamics of the cell membrane. Arithmetic operations on species and parameters are overloaded, allowing arbitrary reaction formulas to be specified using Python syntax. These expressions are then transparently compiled into bytecode that uses NumPy for fast vectorized calculations. At each time step, rxd combines NEURON's integrators with SciPy’s sparse linear algebra library.

  2. Stage fright in singers: three reaction types.

    Science.gov (United States)

    Berghs, Geert

    2008-01-01

    Drawing on both my own personal experience and that of many colleagues and pupils, I shall describe three kinds of reactions to stage fright. The first is the primarily mental reaction of derealization, which involves feeling cut off from fear and decreasing body awareness. The second and third reactions to stage fright involve (a) increased and (b) decreased muscle tonus and their associated breathing patterns. Furthermore, I shall indicate how singers manage to pull themselves together through the very act of producing their first tones. Copyright 2008 S. Karger AG, Basel.

  3. Reaction-diffusion in the NEURON simulator.

    Science.gov (United States)

    McDougal, Robert A; Hines, Michael L; Lytton, William W

    2013-01-01

    In order to support research on the role of cell biological principles (genomics, proteomics, signaling cascades and reaction dynamics) on the dynamics of neuronal response in health and disease, NEURON's Reaction-Diffusion (rxd) module in Python provides specification and simulation for these dynamics, coupled with the electrophysiological dynamics of the cell membrane. Arithmetic operations on species and parameters are overloaded, allowing arbitrary reaction formulas to be specified using Python syntax. These expressions are then transparently compiled into bytecode that uses NumPy for fast vectorized calculations. At each time step, rxd combines NEURON's integrators with SciPy's sparse linear algebra library.

  4. Quantum Radiation Reaction: From Interference to Incoherence.

    Science.gov (United States)

    Dinu, Victor; Harvey, Chris; Ilderton, Anton; Marklund, Mattias; Torgrimsson, Greger

    2016-01-29

    We investigate quantum radiation reaction in laser-electron interactions across different energy and intensity regimes. Using a fully quantum approach which also accounts exactly for the effect of the strong laser pulse on the electron motion, we identify in particular a regime in which radiation reaction is dominated by quantum interference. We find signatures of quantum radiation reaction in the electron spectra which have no classical analogue and which cannot be captured by the incoherent approximations typically used in the high-intensity regime. These signatures are measurable with presently available laser and accelerator technology.

  5. Quantum radiation reaction: from interference to incoherence

    CERN Document Server

    Dinu, Victor; Ilderton, Anton; Marklund, Mattias; Torgrimsson, Greger

    2015-01-01

    We investigate quantum radiation reaction in laser-electron interactions across different energy and intensity regimes. Using a fully quantum approach which also accounts exactly for the effect of the strong laser pulse on the electron motion, we identify in particular a regime in which radiation reaction is dominated by quantum interference. We find signatures of quantum radiation reaction in the electron spectra which have no classical analogue and which cannot be captured by the incoherent approximations typically used in the high-intensity regime. These signatures are measurable with presently available laser and accelerator technology.

  6. Supercritical Fluid Reactions for Coal Processing

    Energy Technology Data Exchange (ETDEWEB)

    Charles A. Eckert

    1997-11-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we developed a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The tautomeric equilibrium of a Schiff base was chosen as one model system and was investigated in supercritical ethane and cosolvent modified supercritical ethane. The Diels-Alder reaction of anthracene and 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) was selected as a second model system, and it was investigated in supercritical carbon dioxide.

  7. Erythropoietin-induced iritis-like reaction.

    Science.gov (United States)

    Beiran, I; Krasnitz, I; Mezer, E; Meyer, E; Miller, B

    1996-01-01

    The present report describes an iritis-like reaction found in 13 patients treated with recombinant human erythropoietin (Eprex), a drug given to hemodialysis patients for their chronic anemia. Among 120 patients being treated by hemodialysis in two centers affiliated with our medical center, ten out of 30 Eprex-treated patients but none of 90 not being treated with Eprex developed this reaction. The observations described support a causal relation between Eprex treatment and the iritis-like reaction. Further investigative effort is needed to establish the mechanism.

  8. [Allergic and toxic cutaneous reactions to plants].

    Science.gov (United States)

    Gambillara, Eleonora; Spertini, Francois; Leimgruber, Annette

    2010-04-21

    Numerous professional or leisure activities expose individuals to plants susceptible to provoke contact allergies. The immunological mechanisms that are responsible for these ailments (delayed cellular reaction linked to allergic dermatitis or immediate IgE mediated reaction of the allergic urticaria) differ according to the plant families involved. A differential diagnosis must be made in the case of the even more frequent non-allergic reactions implying either a simple mechanical irritation, or a contact with toxic substances. The role of UV (phytophotodermatosis), as well as the contact allergy to wood is also evoked in this paper.

  9. Atmospheric Pressure Microwave Assisted Heterogeneous Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Farid Chemat

    2007-07-01

    Full Text Available The purpose of the study was to investigate microwave selective heatingphenomena and their impact on heterogeneous chemical reactions. We also present a toolwhich will help microwave chemists to answer to such questions as “My reaction yields90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes undermicrowaves?” and to have an approximation of their reactions when conducted undermicrowaves with different heterogeneous procedures. This model predicting reactionkinetics and yields under microwave heating is based on the Arrhenius equation, inagreement with experimental data and procedures.

  10. Allergic Reactions to Pine Nut: A Review.

    Science.gov (United States)

    Cabanillas, B; Novak, N

    2015-01-01

    Pine nut is a nutrient-rich food with a beneficial impact on human health. The many bioactive constituents of pine nut interact synergistically to affect human physiology in a favorable way. However, pine nut can trigger dangerous allergic reactions. Severe anaphylactic reactions to pine nut accounted for most of the 45 cases reported in the scientific literature. Pine nut allergy seems to be characterized by low IgE cross-reactivity with other commonly consumed nuts and a high monosensitization rate. The present review provides updated information on allergic reactions to pine nut, molecular characterization of its allergens, and potential homologies with other nut allergens.

  11. Enhancing Activity for the Oxygen Evolution Reaction

    DEFF Research Database (Denmark)

    Frydendal, Rasmus; Busch, Michael; Halck, Niels Bendtsen

    2014-01-01

    Electrochemical production of hydrogen, facilitated in electrolyzers, holds great promise for energy storage and solar fuel production. A bottleneck in the process is the catalysis of the oxygen evolution reaction, involving the transfer of four electrons. The challenge is that the binding energies...... of all reaction intermediates cannot be optimized individually. However, experimental investigations have shown that drastic improvements can be realized for manganese and cobalt-based oxides if gold is added to the surface or used as substrate. We propose an explanation for these enhancements based...... that the oxygen evolution reaction overpotential decreases by 100–300 mV for manganese oxides and 100 mV for cobalt oxides....

  12. On the Violence of High Explosive Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Tarver, C M; Chidester, S K

    2004-02-09

    High explosive reactions can be caused by three general energy deposition processes: impact ignition by frictional and/or shear heating; bulk thermal heating; and shock compression. The violence of the subsequent reaction varies from benign slow combustion to catastrophic detonation of the entire charge. The degree of violence depends on many variables, including the rate of energy delivery, the physical and chemical properties of the explosive, and the strength of the confinement surrounding the explosive charge. The current state of experimental and computer modeling research on the violence of impact, thermal, and shock-induced reactions is reviewed.

  13. Normative Mediation of Reactions to Crowding

    Science.gov (United States)

    Karlin, Robert A.; And Others

    1976-01-01

    This study manipulated norms governing interaction levels in crowded groups of women. Results indicated norms influenced reactions to crowding as predicted. Women reacted most positively when interaction levels were high and most negatively when interaction levels were low. (Author)

  14. Endotoxin contamination delays the foreign body reaction

    NARCIS (Netherlands)

    van Putten, Sander M.; Wubben, Maike; Plantinga, Josee A.; Hennink, Wim E.; van Luyn, Marja J. A.; Harmsen, Martin C.

    2011-01-01

    Biomaterials are at continuous risk of bacterial contamination during production and application. In vivo, bacterial contamination of biomaterials delays the foreign body reaction (FBR). Endotoxins such as lipopolysaccharides (LPS), major constituents of the bacterial cell wall, are potent stimulato

  15. Polymerization as a Model Chain Reaction

    Science.gov (United States)

    Morton, Maurice

    1973-01-01

    Describes the features of the free radical, anionic, and cationic mechanisms of chain addition polymerization. Indicates that the nature of chain reactions can be best taught through the study of macromolecules. (CC)

  16. Reaction cross section of 22C

    Science.gov (United States)

    Togano, Yasuhiro; Samurai Collaboration

    2014-09-01

    Reaction cross section of 22C on a carbon target at an energy of 240 MeV/nucleon have been measured by using the transmission method. The most neutron-rich carbon isotopes 22C is a candidate of a two-neutron halo nucleus. Tanaka et al. [1] measured the reaction cross section of 22C on a hydrogen target at 40 MeV/nucleon. It is showed 22C to have a large matter radius of 5 . 9 +/- 0 . 9 fm, which is much larger than the ones of carbon isotopes with N SAMURAI spectrometer at RIBF. The 22C beam at 240 MeV/nucleon was impinged on a carbon target, and the reaction product was identified by using SAMURAI spectrometer. In the present talk, the extracted reaction cross section and derived matter density distribution of 22C will be presented.

  17. Contact-Allergic Reactions to Cosmetics

    Directory of Open Access Journals (Sweden)

    An Goossens

    2011-01-01

    Full Text Available Contact-allergic reactions to cosmetics may be delayed-type reactions such as allergic and photo-allergic contact dermatitis, and more exceptionally also immediate-type reactions, that is, contact urticaria. Fragrances and preservative agents are the most important contact allergens, but reactions also occur to category-specific products such as hair dyes and other hair-care products, nail cosmetics, sunscreens, as well as to antioxidants, vehicles, emulsifiers, and, in fact, any possible cosmetic ingredient. Patch and prick testing to detect the respective culprits remains the golden standard for diagnosis, although additional tests might be useful as well. Once the specific allergens are identified, the patients should be informed of which products can be safely used in the future.

  18. Positive roles of compartmentalization in internal reactions.

    Science.gov (United States)

    Ichihashi, Norikazu; Yomo, Tetsuya

    2014-10-01

    Recently, many researchers have attempted to construct artificial cell models using a bottom-up approach in which various biochemical reactions that involve a defined set of molecules are reconstructed in cell-like compartments, such as liposomes and water-in-oil droplets. In many of these studies, the cell-like compartments have acted only as containers for the encapsulated biochemical reactions, whereas other studies have indicated that compartmentalization improves the rates and yields of these reactions. Here, we introduce two ways in which compartmentalization can improve internal reactions: the isolation effect and the condensation effect. These positive effects of compartmentalization might have played an important role in the genesis of the first primitive cell on early Earth.

  19. Biocatalytic Process Design and Reaction Engineering

    Directory of Open Access Journals (Sweden)

    R. Wohlgemuth

    2017-07-01

    Full Text Available Biocatalytic processes occurring in nature provide a wealth of inspiration for manufacturing processes with high molecular economy. The molecular and engineering aspects of bioprocesses converting available raw materials into valuable products are therefore of much industrial interest. Modular reaction platforms and straightforward working paths, from the fundamental understanding of biocatalytic systems in nature to the design and reaction engineering of novel biocatalytic processes, have been important for shortening development times. Building on broadly applicable reaction platforms and tools for designing biocatalytic processes and their reaction engineering are key success factors. Process integration and intensification aspects are illustrated with biocatalytic processes to numerous small-molecular weight compounds, which have been prepared by novel and highly selective routes, for applications in the life sciences and biomedical sciences.

  20. Enzyme Reactions in Nanoporous, Picoliter Volume Containers

    Energy Technology Data Exchange (ETDEWEB)

    Siuti, Piro [ORNL; Retterer, Scott T [ORNL; Choi, Chang Kyoung [Michigan Technological University; Doktycz, Mitchel John [ORNL

    2012-01-01

    Advancements in nanoscale fabrication allow creation of small volume reaction containers that can facilitate the screening and characterization of enzymes. A porous, ~19 pL volume vessel has been used in this work to carry out enzyme reactions under varying substrate concentrations. Glucose oxidase and horseradish peroxidase can be contained in these structures and diffusively fed with a solution containing glucose and the fluorogenic substrate Amplex Red through the engineered nanoscale pore structure. Fluorescent microscopy was used to monitor the reaction, which was carried out under microfluidic control. Kinetic characteristics of the enzyme were evaluated and compared with results from conventional scale reactions. These picoliter, nanoporous containers can facilitate quick determination of enzyme kinetics in microfluidic systems without the requirement of surface tethering and can be used for applications in drug discovery, clinical diagnostics and high-throughput screening.

  1. Micelle Catalysis of an Aromatic Substitution Reaction

    Science.gov (United States)

    Corsaro, Gerald; Smith J. K.

    1976-01-01

    Describes an experiment in which the iodonation of aniline reaction is shown to undergo catalysis in solution of sodium lauryl sulfate which forms micelles with negatively charged pseudo surfaces. (MLH)

  2. Role of multifragmentation in spallation reactions

    CERN Document Server

    Botvina, A S

    2008-01-01

    In nuclear reactions induced by hadrons and ions of high energies, nuclei can disintegrate into many fragments during a short time (~100 fm/c). This phenomenon known as nuclear multifragmentation was under intensive investigation last 20 years. It was established that multifragmentation is an universal process taking place in all reactions when the excitation energy transferred to nuclei is high enough, more than 3 MeV per nucleon, independently on the initial dynamical stage of the reactions. Very known compound nucleus decay processes (sequential evaporation and fission), which are usual for low energies, disappear and multifragmentation dominates at high excitation energy. For this reason, calculation of multifragmentation must be carried on in all cases when production of highly excited nuclei is expected, including spallation reactions. From the other hand, one can consider multifragmentation as manifestation of the liquid-gas phase transition in finite nuclei. This gives way for studying nuclear matter ...

  3. Case report: anaphylactic reaction to guaifenesin.

    Science.gov (United States)

    Ray, Manujendra; Faltay, Bela; Haller, Nairmeen Awad

    2009-12-01

    Adverse drug reactions lead to a significant number of hospital admissions each year and thus contribute to the overall financial burden of health care. Some of these drug reactions are allergic responses. As the overall predictability of allergic responses to drugs remains low, efforts to improve our understanding of the processes underlying these responses continue as we strive toward the ultimate goal of primary prevention. Allergic reactions range from mild pruritic to severe systemic anaphylactic responses. We report a case of a young healthy man who developed an anaphylactic reaction to an over-the-counter expectorant. A skin test showed that the patient had an immunoglobulin E-mediated allergic response to guaifenesin, one of the components of commonly available cough medications. Our review of published literature showed that this is the first report of a severe allergic response to guaifenesin.

  4. Acoustic Resonance Reaction Control Thruster (ARCTIC) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop and demonstrate the innovative Acoustic Resonance Reaction Control Thruster (ARCTIC) to provide rapid and reliable in-space impulse...

  5. Mechanochemical reactions on copper-based compounds

    NARCIS (Netherlands)

    Castricum, H.L.; Bakker, H.; Poels, E.K.

    1999-01-01

    Mechanochemical reactions of copper and copper oxides with oxygen and carbon dioxide are discussed, as well as decomposition and reduction of copper compounds by mechanical milling under high-vacuum conditions.

  6. Localized nonequilibrium nanostructures in surface chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrand, M; Ipsen, M; Mikhailov, A S; Ertl, G [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

    2003-06-01

    Nonequilibrium localized stationary structures of submicrometre and nanometre sizes can spontaneously develop under reaction conditions on a catalytic surface. These self-organized structures emerge because of the coupling between the reaction and a structural phase transition in the substrate. Depending on the reaction conditions they can either correspond to densely covered spots (islands), inside which the reaction predominantly proceeds, or local depletions (holes) in a dense adsorbate layer with a very small reactive output in comparison to the surroundings. The stationary localized solutions are constructed using the singular perturbation approximation. These results are compared with numerical simulations, where special adaptive grid algorithms and numerical continuation of stationary profiles are used. Numerical investigations beyond the singular perturbation limit are also presented.

  7. organic reaction mechanism controversy: pedagogical implications ...

    African Journals Online (AJOL)

    Preferred Customer

    nature of reaction mechanism in organic chemistry as to whether it can be .... The graduate assistant, chemistry teacher and final year chemistry students were .... Rollnick (3), Sykes (10), and Bhattacharyya and Bodner (11) on these issues ...

  8. Reaction Wheel Disturbance Model Extraction Software Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reaction wheel mechanical noise is one of the largest sources of disturbance forcing on space-based observatories. Such noise arises from mass imbalance, bearing...

  9. Reaction Wheel with Embedded MEMS IMU Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reaction wheels are used to stabilize satellites and to slew their orientation from object to object with precision and accuracy by varying the rotational speed of...

  10. Graphic Characterization and Taxonomy of Organic Reactions.

    Science.gov (United States)

    Fujita, Shinsaku

    1990-01-01

    Discussed are the substructures (subgraphs) of imaginary transition structures that provide an effective approach to the characterization of organic reactions. A comparison of conventional methods and this method is presented. (CW)

  11. Adverse Drug Reactions in Children: Types, Incidence,

    African Journals Online (AJOL)

    Drug Reactions in Children: Types, Incidence, and Risk Factors. Nigerian fownal of Paedzkztrits 2006; ... 'prescription, non-prescription, biological and herbal. Lagos'State University ..... intensity of data collection and possibility of prevention.

  12. Multistage reaction pathways in detonating RDX

    Science.gov (United States)

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

    2017-01-01

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine cystal. Rapid production of N2 and H2O within ˜10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen- rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N2 and H2O productions.

  13. Towards Quantum Transport for Central Nuclear Reactions

    CERN Document Server

    Danielewicz, Pawel; Barker, Brent

    2016-01-01

    Nonequilibrium Green's functions represent a promising tool for describing central nuclear reactions. Even at the single-particle level, though, the Green's functions contain more information that computers may handle in the foreseeable future. In this study, we explore slab collisions in one dimension, first in the mean field approximation and demonstrate that only function elements close to the diagonal in arguments are relevant, in practice, for the reaction calculations. This bodes well for the application of the Green's functions to the reactions. Moreover we demonstrate that an initial state for a reaction calculation may be generated through adiabatic transformation of interactions. Finally, we report on our progress in incorporating correlations into the dynamic calculations.

  14. CHEMICAL REACTION: DIAGNOSIS AND TOWARDS REMEDY OF ...

    African Journals Online (AJOL)

    Preferred Customer

    subscripts in a chemical reaction a new teaching-learning strategy is suggested: Tetrahedral. - in - Zone .... Approaches from Pedagogy and Psychology. According .... matching pedagogical strategies to the learning styles of students. It maps ...

  15. Injection site reactions after subcutaneous oligonucleotide therapy

    NARCIS (Netherlands)

    van Meer, L. (Leonie); M. Moerland (Matthijs); Gallagher, J. (Jolie); M.B.A. van Doorn (Martijn); E.P. Prens (Errol); A.F. Cohen; Rissmann, R. (Robert); J. Burggraaf (Jacobus)

    2016-01-01

    textabstractOligonucleotides (ONs) are short fragments of nucleic acids, currently being investigated as therapeutic agents. When administered subcutaneously (sc), ONs cause a specific local reaction originating around the injection site, such as erythema, itching, discomfort and pain, including

  16. Reaction Wheel Disturbance Model Extraction Software Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reaction wheel disturbances are some of the largest sources of noise on sensitive telescopes. Such wheel-induced mechanical noises are not well characterized....

  17. Density functional calculations on hydrocarbon isodesmic reactions

    Science.gov (United States)

    Fortunelli, Alessandro; Selmi, Massimo

    1994-06-01

    Hartree—Fock, Hartree—Fock-plus-correlation and self-consistent Kohn—Sham calculations are performed on a set of hydrocarbon isodesmic reactions, i.e. reactions among hydrocarbons in which the number and type of carbon—carbon and carbon—hydrogen bonds is conserved. It is found that neither Hartree—Fock nor Kohn—Sham methods correctly predict standard enthalpies, Δ Hr(298 K), of these reactions, even though — for reactions involving molecules containing strained double bonds — the agreement between the theoretical estimates and the experimental values of Δ Hr seems to be improved by the self-consistent solution of the Kohn—Sham equations. The remaining discrepancies are attributed to intramolecular dispersion effects, that are not described by ordinary exchange—correlation functionals, and are eliminated by introducing corrections based on a simple semi-empirical model.

  18. Taiwanese student reaction to English language internet ...

    African Journals Online (AJOL)

    Taiwanese student reaction to English language internet teleconferencing ... strengthen the integrative motivation of students who rarely have the opportunity to ... Perceptions of the distance-learning experience were often framed in terms of

  19. Connectionist and diffusion models of reaction time.

    Science.gov (United States)

    Ratcliff, R; Van Zandt, T; McKoon, G

    1999-04-01

    Two connectionist frameworks, GRAIN (J. L. McClelland, 1993) and brain-state-in-a-box (J. A. Anderson, 1991), and R. Ratcliff's (1978) diffusion model were evaluated using data from a signal detection task. Dependent variables included response probabilities, reaction times for correct and error responses, and shapes of reaction-time distributions. The diffusion model accounted for all aspects of the data, including error reaction times that had previously been a problem for all response-time models. The connectionist models accounted for many aspects of the data adequately, but each failed to a greater or lesser degree in important ways except for one model that was similar to the diffusion model. The findings advance the development of the diffusion model and show that the long tradition of reaction-time research and theory is a fertile domain for development and testing of connectionist assumptions about how decisions are generated over time.

  20. Chemical Reactions at Surfaces. Final Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    None

    2003-02-21

    The Gordon Research Conference (GRC) on Chemical Reactions at Surfaces was held at Holiday Inn, Ventura, California, 2/16-21/03. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  1. Method for predicting enzyme-catalyzed reactions

    Science.gov (United States)

    Hlavacek, William S.; Unkefer, Clifford J.; Mu, Fangping; Unkefer, Pat J.

    2013-03-19

    The reactivity of given metabolites is assessed using selected empirical atomic properties in the potential reaction center. Metabolic reactions are represented as biotransformation rules. These rules are generalized from the patterns in reactions. These patterns are not unique to reactants but are widely distributed among metabolites. Using a metabolite database, potential substructures are identified in the metabolites for a given biotransformation. These substructures are divided into reactants or non-reactants, depending on whether they participate in the biotransformation or not. Each potential substructure is then modeled using descriptors of the topological and electronic properties of atoms in the potential reaction center; molecular properties can also be used. A Support Vector Machine (SVM) or classifier is trained to classify a potential reactant as a true or false reactant using these properties.

  2. Electrodisintegration of the deuteron in nuclear reactions

    Science.gov (United States)

    Liu, L. C.; Thaler, R. M.

    1990-06-01

    We estimate that the electrodisintegration of the deuteron contributes at least 25% of the total reaction cross section when the deuteron interacts with a nucleus of charge Z>~40 at a kinetic energy lower than 50 MeV. The neglect of this breakup channel in deuteron-nucleus optical potentials might lead to unrealistic predictions for the mass and energy dependence of the total deuteron reaction cross sections.

  3. Electrodisintegration of the deuteron in nuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L.C. (Theoretical Division, T-2, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)); Thaler, R.M. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA) Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (USA))

    1990-06-01

    We estimate that the electrodisintegration of the deuteron contributes at least 25% of the total reaction cross section when the deuteron interacts with a nucleus of charge {ital Z}{approx gt}40 at a kinetic energy lower than 50 MeV. The neglect of this breakup channel in deuteron-nucleus optical potentials might lead to unrealistic predictions for the mass and energy dependence of the total deuteron reaction cross sections.

  4. Mechanochemical Reactions of Elastomers with Metals.

    Science.gov (United States)

    1984-09-01

    34i neeeeewy a"md&tf by week nmbo) Elastomers, Fracture, Free-radical reactions, Mechanochemistry , Metals , Macromolecular rupture, Organic radicals...from metallic grey to red-brown, indicating the formation of an increased amount of iron oxide . When this oxidized powder was mixed into SBR and the...Project NR 092-555In ID Technical Report No. 33 MECHANOCHEMICAL REACTIONS OF ELASTOMERS WITH METALS by A. N. Gent and W. R. Rodgers Institute of

  5. On Back-reaction in Special Relativity

    CERN Document Server

    Nelson, William M

    2013-01-01

    Back-reaction of fields plays an important role in the generation of particle masses and the mass-energy equivalence of special relativity, but the most natural demonstrations using classical models result in apparent errors such as the notorious "4/3" problem. Here we discuss the resolution of these discrepancies within the underlying atomic description of matter, with the aim of encouraging classroom discussion of back-reaction and its connection to relativistic effects.

  6. Adverse drug reactions in hospitalized Colombian children.

    Science.gov (United States)

    de Las Salas, Roxana; Díaz-Agudelo, Daniela; Burgos-Flórez, Francisco Javier; Vaca, Claudia; Serrano-Meriño, Dolores Vanessa

    2016-09-30

    The occurrence of adverse drug reactions is an important issue due to the lack of drug safety data in children. To describe the Adverse Drug Reactions in inpatient children under 6 years of age in two general pediatrics wards located in Barranquilla, Colombia. A prospective cohort study based on intensive pharmacovigilance was conducted during six months in order to monitor the emergence of Adverse Drug Reactions in inpatients children under 6 years of age with at least one medication prescribed. The study was conducted in two pediatric wards of two hospitals located in Barranquilla, Colombia. Naranjo´s Algorithm was used to evaluate imputability, the modified Hartwig and Siegel assessment scale to establish severity and the Schumock and Thornton criteria to determine preventability. Of a total of 772 monitored patients, 156 Adverse Drug Reactions were detected on 147 children. The cumulative incidence of Adverse Drug Reactions was 19.0% (147/772); the incidence density was 37.6 Adverse Drug Reactions per 1,000 patients-days (147/3,913). The frequency was higher in children under 2 years of age (12.7%). Emergence of Adverse Drug Reactions was higher in male patients (RR= 1.66; 95% CI= 1.22-2.22, p= 0.001) and in those who used systemic antibiotics (RR= 1.82; 95% CI= 1.17-2.82, p= 0.005). Adverse Drug Reactions are common among hospitalized children and represent an additional burden of morbidity and risk, particularly in those who used several medicines, including antibiotics.

  7. Direct Reactions with MoNA-LISA

    Science.gov (United States)

    Kuchera, Anthony

    2016-03-01

    Nuclear reactions can be used to probe the structure of nuclei. Direct reactions, which take place on short time scales, are well-suited for experiments with beams of short-lived nuclei. One such reaction is nucleon knockout where a proton or neutron is removed from the incoming beam from the interaction with a target. Single nucleon knockout reactions have been used to study the single-particle nature of nuclear wave functions. A recent experiment at the National Superconducting Cyclotron Laboratory was performed to measure cross sections from single nucleon knockout reactions for several p-shell nuclei. Detection of the residual nucleus in coincidence with any gamma rays emitted from the target allowed cross sections to ground and excited states to be measured. Together with input from reaction theory, ab initio structure theories can be tested. Simultaneously the accuracy of knockout reaction models can be validated by detecting the knocked out neutron with the Modular Neutron Array and Large multi-Institutional Scintillator Array (MoNA-LISA). Preliminary results from this experiment will be shown. Knockout reactions can also be used to populate nuclei which are neutron unbound, thus emit neutrons nearly instantaneously. The structure of these nuclei, therefore, cannot be probed with gamma ray spectroscopy. However, with large neutron detectors like MoNA-LISA the properties of these short-lived nuclei are able to be measured. Recent results using MoNA-LISA to study the structure of neutron-rich nuclei will be presented. The author would like to acknowledge support from the NNSA and NSF.

  8. Polycyclic alkaloids via transannular Mannich reactions

    DEFF Research Database (Denmark)

    Vital, Paulo; Hosseini, Masood; Shanmugham, M. S.

    2009-01-01

    The tricyclic compound 13, representing the framework of the cylindricine 4 and lepadiformine 5 alkaloids, was prepared in a single operation via the first example of a transannular Mannich reaction involving a macrocyclic diketoamine 12.......The tricyclic compound 13, representing the framework of the cylindricine 4 and lepadiformine 5 alkaloids, was prepared in a single operation via the first example of a transannular Mannich reaction involving a macrocyclic diketoamine 12....

  9. (--SCLAREOL CONVERSION IN RITTER'S REACTION CONDITIONS

    Directory of Open Access Journals (Sweden)

    S. Kovalskaya

    2012-12-01

    Full Text Available The main products of sclareol (1 Ritter’s reaction in mild conditions are (8R,13R-Labd-14(15-en-8,13-diacetamide (2 (8R,13S-Labd-14(15-en-8,13-diacetamide (3 stereoisomeric on C13 atom and having unrearranged native diol skeleton. We present in the current communication the results of sclareol converting (1 into nitrogen-containing labdanes in the Ritter’s reaction conditions.

  10. Langevin Equations for Reaction-Diffusion Processes

    Science.gov (United States)

    Benitez, Federico; Duclut, Charlie; Chaté, Hugues; Delamotte, Bertrand; Dornic, Ivan; Muñoz, Miguel A.

    2016-09-01

    For reaction-diffusion processes with at most bimolecular reactants, we derive well-behaved, numerically tractable, exact Langevin equations that govern a stochastic variable related to the response field in field theory. Using duality relations, we show how the particle number and other quantities of interest can be computed. Our work clarifies long-standing conceptual issues encountered in field-theoretical approaches and paves the way for systematic numerical and theoretical analyses of reaction-diffusion problems.

  11. Characteristics of equilibrium reaction of zolazepam.

    Science.gov (United States)

    Hong, W H; Szulczewski, D H

    1981-06-01

    The equilibrium reaction of zolazepam, a pyrazolodiazepinone, was studied and analyzed using the approach used previously for other pyrazolodiazepinone derivatives. The intrinsic ring closure equilibrium constant for this reaction was approximately 100 times larger than that observed for pyrazolodiazepinones studied previously. This study illustrates that the diazepinone ring can dominate in equilibrium mixtures formed at pH values far below the pKa of the corresponding form.

  12. Sinterable Powders from Laser Driven Reactions

    Science.gov (United States)

    1980-07-01

    When Dfat . Ente.d) READ INSTRUCTIONS REPORT DOCUMENTATION PAGE BEFORE COMPLETING FORM I REPORT NUMBER i2. GOVT ACCESSION NO. 3 RECIPIENT’S CATALOG...LIST OF FIGURES FPage 1. Ordered packing of monodispersed 0.2 Pm diameter Si0 2 spheres. 2 2. Schematic of powder synthesis cell . 7 3. Mie absorption...and resulting powder particle size (reaction cell pressure of 0.20 atm). 29 10. The effect of velocity on the silicon synthesis reaction flame

  13. Palladium-Catalyzed, Enantioselective Heine Reaction.

    Science.gov (United States)

    Punk, Molly; Merkley, Charlotte; Kennedy, Katlyn; Morgan, Jeremy B

    2016-07-01

    Aziridines are important synthetic intermediates for the generation of nitrogen-containing molecules. N-Acylaziridines undergo rearrangement by ring expansion to produce oxazolines, a process known as the Heine reaction. The first catalytic, enantioselective Heine reaction is reported for meso-N-acylaziridines where a palladium(II)-diphosphine complex is employed. The highly enantioenriched oxazoline products are valuable organic synthons and potential ligands for transition-metal catalysis.

  14. Kinematical coincidence method in transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others

    2013-07-01

    A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of {sup 10}Be+p→{sup 9}Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.

  15. Coulomb dissociation studies for astrophysical thermonuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Motobayashi, T. [Dept. of Physics, Rikkyo Univ., Toshima, Tokyo (Japan)

    1998-06-01

    The Coulomb dissociation method was applied to several radiative capture processes of astrophysical interest. The method has an advantage of high experimental efficiency, which allow measurements with radioactive nuclear beams. The reactions {sup 13}N(p,{gamma}){sup 14}O and {sup 7}Be(p,{gamma}){sup 8}B are mainly discussed. They are the key reaction in the hot CNO cycle in massive stars and the one closely related to the solar neutrino problem, respectively. (orig.)

  16. Maillard reaction products in pet foods

    OpenAIRE

    Rooijen, van, J.

    2015-01-01

    Pet dogs and cats around the world are commonly fed processed commercial foods throughout their lives. Often heat treatments are used during the processing of these foods to improve nutrient digestibility, shelf life, and food safety. Processing is known to induce the Maillard reaction, in which a reducing sugar binds to a free reactive amino group of an amino acid. In intact proteins, the ε-amino group of lysine is the most abundant free amino group. The reaction reduces the bioavail...

  17. Theory of (e, 2e) reactions

    Science.gov (United States)

    Byron, F. W.; Joachain, C. J.

    1989-08-01

    A comprehensive survey is given of the theory of (e, 2e) reactions. We begin by discussing the kinematics of these reactions, with special attention devoted to the coplanar asymmetric (Ehrhardt-type) geometry and the fully symmetric geometry in which most of the recent (e, 2e) coincidence measurements have been performed. We then review the foundations of the theory of the ionization of atoms by electron impact, first for one-electron atoms and then for target atoms with N electrons. Next, we discussed the Wannier theory of threshold ionization and its excitations. We then turn to the analysis of (e, 2e) reactions at intermediate and high energies. The theory of fast coplanar asymmetric (e, 2e) reactions is analyzed and it is shown that the eikonal-Born series method successfully accounts for all the dynamical features of these reactions. In particular, it is shown that second order effects are essential in explaining all the features exhibited by the measured by the measured triple differential cross sections at intermediate energies. Finally, we review the theory of fast symmetric (e, 2e) reactions. We consider first the (e, 2e) spectroscopy regime in which the momentum transfer Δ is large, but the recoil momentum Q of the ion is small or moderate. We then turn to the regime of large Δ and large Q, for which second order effects are of paramount importance, so that the coplanar symmetric triple differential cross section exhibits a striking behaviour in the large angle region.

  18. Calculation of the energetics of chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dunning, T.H. Jr.; Harding, L.B.; Shepard, R.L.; Harrison, R.J.

    1988-01-01

    To calculate the energetics of chemical reactions we must solve the electronic Schroedinger equation for the molecular conformations of importance for the reactive encounter. Substantial changes occur in the electronic structure of a molecular system as the reaction progresses from reactants through the transition state to products. To describe these changes, our approach includes the following three elements: the use of multiconfiguration self-consistent field wave functions to provide a consistent zero-order description of the electronic structure of the reactants, transition state, and products; the use of configuration interaction techniques to describe electron correlation effects needed to provide quantitative predictions of the reaction energetics; and the use of large, optimized basis sets to provide the flexibility needed to describe the variations in the electronic distributions. With this approach we are able to study reactions involving as many as 5--6 atoms with errors of just a few kcal/mol in the predicted reaction energetics. Predictions to chemical accuracy, i.e., to 1 kcal/mol or less, are not yet feasible, although continuing improvements in both the theoretical methodology and computer technology suggest that this will soon be possible, at least for reactions involving small polyatomic species. 4 figs.

  19. Advances in lipase-catalyzed esterification reactions.

    Science.gov (United States)

    Stergiou, Panagiota-Yiolanda; Foukis, Athanasios; Filippou, Michalis; Koukouritaki, Maria; Parapouli, Maria; Theodorou, Leonidas G; Hatziloukas, Efstathios; Afendra, Amalia; Pandey, Ashok; Papamichael, Emmanuel M

    2013-12-01

    Lipase-catalyzed esterification reactions are among the most significant chemical and biochemical processes of industrial relevance. Lipases catalyze hydrolysis as well as esterification reactions. Enzyme-catalyzed esterification has acquired increasing attention in many applications, due to the significance of the derived products. More specifically, the lipase-catalyzed esterification reactions attracted research interest during the past decade, due to an increased use of organic esters in biotechnology and the chemical industry. Lipases, as hydrolyzing agents are active in environments, which contain a minimum of two distinct phases, where all reactants are partitioned between these phases, although their distribution is not fixed and changes as the reaction proceeds. The kinetics of the lipase-catalyzed reactions is governed by a number of factors. This article presents a thorough and descriptive evaluation of the applied trends and perspectives concerning the enzymatic esterification, mainly for biofuel production; an emphasis is given on essential factors, which affect the lipase-catalyzed esterification reaction. Moreover, the art of using bacterial and/or fungal strains for whole cell biocatalysis purposes, as well as carrying out catalysis by various forms of purified lipases from bacterial and fungal sources is also reviewed.

  20. Cascade reactions catalyzed by metal organic frameworks.

    Science.gov (United States)

    Dhakshinamoorthy, Amarajothi; Garcia, Hermenegildo

    2014-09-01

    Cascade or tandem reactions where two or more individual reactions are carried out in one pot constitute a clear example of process intensification, targeting the maximization of spatial and temporal productivity with mobilization of minimum resources. In the case of catalytic reactions, cascade processes require bi-/multifunctional catalysts that contain different classes of active sites. Herein, we show that the features and properties of metal-organic frameworks (MOFs) make these solids very appropriate materials for the development of catalysts for cascade reactions. Due to composition and structure, MOFs can incorporate different types of sites at the metal nodes, organic linkers, or at the empty internal pores, allowing the flexible design and synthesis of multifunctional catalysts. After some introductory sections on the relevance of cascade reactions from the point of view of competitiveness, sustainability, and environmental friendliness, the main part of the text provides a comprehensive review of the literature reporting the use of MOFs as heterogeneous catalysts for cascade reactions including those that combine in different ways acid/base, oxidation/reduction, and metal-organic centers. The final section summarizes the current state of the art, indicating that the development of a first commercial synthesis of a high-added-value fine chemical will be a crucial milestone in this area.