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Sample records for proton structure functions

  1. Proton structure functions at small x

    SciTech Connect

    Hentschinski, Martin

    2015-01-01

    Proton structure functions are measured in electron-proton collision through inelastic scattering of virtual photons with virtuality Q on protons; x denotes the momentum fraction carried by the struck parton. Proton structure functions are currently described with excellent accuracy in terms of scale dependent parton distribution functions, defined in terms of collinear factorization and DGLAP evolution in Q. With decreasing x however, parton densities increase and are ultimately expected to saturate. In this regime DGLAP evolution will finally break down and non-linear evolution equations w.r.t x are expected to take over. In the first part of the talk we present recent result on an implementation of physical DGLAP evolution. Unlike the conventional description in terms of parton distribution functions, the former describes directly the Q dependence of the measured structure functions. It is therefore physical insensitive to factorization scheme and scale ambiguities. It therefore provides a more stringent test of DGLAP evolution and eases the manifestation of (non-linear) small x effects. It however requires a precise measurement of both structure functions F2 and FL, which will be only possible at future facilities, such as an Electron Ion Collider. In the second part we present a recent analysis of the small x region of the combined HERA data on the structure function F2. We demonstrate that (linear) next-to-leading order BFKL evolution describes the effective Pomeron intercept, determined from the combined HERA data, once a resummation of collinear enhanced terms is included and the renormalization scale is fixed using the BLM optimal scale setting procedure. We also provide a detailed description of the Q and x dependence of the full structure functions F2 in the small x region, as measured at HERA. As a result, predictions for the structure function FL are found to be in agreement with the existing HERA

  2. Proton structure functions at small x

    DOE PAGESBeta

    Hentschinski, Martin

    2015-01-01

    Proton structure functions are measured in electron-proton collision through inelastic scattering of virtual photons with virtuality Q on protons; x denotes the momentum fraction carried by the struck parton. Proton structure functions are currently described with excellent accuracy in terms of scale dependent parton distribution functions, defined in terms of collinear factorization and DGLAP evolution in Q. With decreasing x however, parton densities increase and are ultimately expected to saturate. In this regime DGLAP evolution will finally break down and non-linear evolution equations w.r.t x are expected to take over. In the first part of the talk we present recentmore » result on an implementation of physical DGLAP evolution. Unlike the conventional description in terms of parton distribution functions, the former describes directly the Q dependence of the measured structure functions. It is therefore physical insensitive to factorization scheme and scale ambiguities. It therefore provides a more stringent test of DGLAP evolution and eases the manifestation of (non-linear) small x effects. It however requires a precise measurement of both structure functions F2 and FL, which will be only possible at future facilities, such as an Electron Ion Collider. In the second part we present a recent analysis of the small x region of the combined HERA data on the structure function F2. We demonstrate that (linear) next-to-leading order BFKL evolution describes the effective Pomeron intercept, determined from the combined HERA data, once a resummation of collinear enhanced terms is included and the renormalization scale is fixed using the BLM optimal scale setting procedure. We also provide a detailed description of the Q and x dependence of the full structure functions F2 in the small x region, as measured at HERA. As a result, predictions for the structure function FL are found to be in agreement with the existing HERA data.« less

  3. Sub-structures in hadrons and proton structure functions

    NASA Astrophysics Data System (ADS)

    Arash, Firooz; Khorramian, Ali N.

    2001-04-01

    We calculate the partonic structure of constituent quark in the Next-to-Leading Order. Using a convolution method, Structure function of proton is presented. While the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contributions coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the SU(2) symmetry breaking of the nucleon sea and the observed violation of Gottfried sum rule. Excellent agreement with data in a wide range of x = [10 -6, 1] and Q2 = [0.5, 5000] GeV2 for Fp2 is reached.

  4. Spin structure functions: Proton / deuteron measurements in the resonance region

    SciTech Connect

    Mark Jones; RSS Collaboration

    2006-02-01

    The RSS experiment ran in Hall C at Jefferson Lab and measured the proton and deuteron beam-target asymmetries for parallel and perpendicular target fields over a W range from pion threshold to 1.9 GeV at Q{sup 2} {approx} 1.3 GeV{sup 2}. Preliminary results for the proton spin structure functions g{sub 1} and g{sub 2} are presented.

  5. Polarized Structure Functions: Proton/Deuteron Measurements in Hall C

    SciTech Connect

    Oscar A. Rondon

    2005-02-01

    The study of the nucleon polarized structure functions has matured beyond the inclusive measurements of the past to the investigation of all eight quark distribution functions in the nucleon. Jefferson Lab's Hall C program of polarized structure functions studies started with a measurement of the proton and deuteron spin structure in the resonances at Q2 {approx} 1.3 [GeV/c]2. This work will be extended for the proton to more than 5 [GeV/c]2 for both DIS and the resonances in the upcoming SANE experiment. SANE will use a novel non-magnetic very large solid angle detector, BETA. Semi-inclusive asymmetries will be measured to determine the flavor composition of the nucleon spin in the recently approved Semi-SANE experiment. The 11 GeV energy upgrade will open new opportunities to study other functions, such as the transversity, Collins and Sievers functions, using vertical polarized targets.

  6. Polarized Structure Functions: Proton/Deuteron Measurements in Hall C

    SciTech Connect

    Rondon, Oscar A.

    2005-02-10

    The study of the nucleon polarized structure functions has matured beyond the inclusive measurements of the past to the investigation of all eight quark distribution functions in the nucleon. Jefferson Lab's Hall C program of polarized structure functions studies started with a measurement of the proton and deuteron spin structure in the resonances at Q2 {approx} 1.3 [GeV/c]2. This work will be extended for the proton to more than 5 [GeV/c]2 for both DIS and the resonances in the upcoming SANE experiment. SANE will use a novel non-magnetic very large solid angle detector, BETA. Semi-inclusive asymmetries will be measured to determine the flavor composition of the nucleon spin in the recently approved Semi -- SANE experiment. The 11 GeV energy upgrade will open new opportunities to study other functions, such as the transversity, Collins and Sievers functions, using vertical polarized targets.

  7. The proton and deuteron F2 structure function at low Q2

    SciTech Connect

    Tvaskis, Vladas; Asaturyan, Razmik; Baker, Oliver; Blok, Henk; Bosted, Peter; Boswell, Melissa; Bruell, Antje; Christy, Michael; Cochran, Anthony; Ent, Rolf; Filippone, Bradley; Gasparian, Ashot; Keppel, Cynthia; Kinney, Edward; Lapikas, L; Lorenzon, Wolfgang; Mammei, Juliette; Martin, J W; Mkrtchyan, Hamlet; Niculescu, Maria-Ioana; Piercey, Rodney; Potterveld, David; Smith, Gregory; Spurlock, Kurt; Van der Steenhoven, Gerard; Stepanyan, Stepan; Tadevosyan, Vardan; Wood, Stephen

    2010-06-01

    Measurements of the proton and deuteron F2 structure functions are presented. The data, taken at Je erson Lab Hall C, span the four-momentum transfer range 0:06 < Q2 < 2:8 GeV2, and Bjorken x values from 0.009 to 0.45, thus extending the knowledge of F2 to low values of Q2 at low x. Next-to-next-to-leading order calculations using recent parton distribution functions start to deviate from the data for Q2 < 2 GeV2 at the low and high x-values. Down to the lowest value of Q2, the structure function is in good agreement with a parameterization of F2 based on data that have been taken at much higher values of Q2 or much lower values of x, and which is constrained by data at the photon point. The ratio of the deuteron and proton structure functions at low x remains well described by a logarithmic dependence on Q2 at low Q2.

  8. Proton and deuteron spin structure function measurements in the resonance region

    SciTech Connect

    F.R. Wesselmann

    2003-07-01

    The RSS collaboration has measured the spin structure functions of the proton and the deuteron at Jefferson Lab using the Hall C HMS spectrometer, a polarized electron beam and a polarized solid target. The asymmetries A and A were measured in the region of the nucleon resonances (0.82 GeV < W < 1.98 GeV) at an average four momentum transfer of Q2 = 1.3 GeV2. The extracted spin structure functions and their kinematic dependence will make a significant contribution in the study of higher-twist effects and polarized duality tests. A description of the experiment and the latest findings of the analysis will be presented.

  9. Advances in functional and structural imaging of the human lung using proton MRI.

    PubMed

    Miller, G Wilson; Mugler, John P; Sá, Rui C; Altes, Talissa A; Prisk, G Kim; Hopkins, Susan R

    2014-12-01

    The field of proton lung MRI is advancing on a variety of fronts. In the realm of functional imaging, it is now possible to use arterial spin labeling (ASL) and oxygen-enhanced imaging techniques to quantify regional perfusion and ventilation, respectively, in standard units of measurement. By combining these techniques into a single scan, it is also possible to quantify the local ventilation-perfusion ratio, which is the most important determinant of gas-exchange efficiency in the lung. To demonstrate potential for accurate and meaningful measurements of lung function, this technique was used to study gravitational gradients of ventilation, perfusion, and ventilation-perfusion ratio in healthy subjects, yielding quantitative results consistent with expected regional variations. Such techniques can also be applied in the time domain, providing new tools for studying temporal dynamics of lung function. Temporal ASL measurements showed increased spatial-temporal heterogeneity of pulmonary blood flow in healthy subjects exposed to hypoxia, suggesting sensitivity to active control mechanisms such as hypoxic pulmonary vasoconstriction, and illustrating that to fully examine the factors that govern lung function it is necessary to consider temporal as well as spatial variability. Further development to increase spatial coverage and improve robustness would enhance the clinical applicability of these new functional imaging tools. In the realm of structural imaging, pulse sequence techniques such as ultrashort echo-time radial k-space acquisition, ultrafast steady-state free precession, and imaging-based diaphragm triggering can be combined to overcome the significant challenges associated with proton MRI in the lung, enabling high-quality three-dimensional imaging of the whole lung in a clinically reasonable scan time. Images of healthy and cystic fibrosis subjects using these techniques demonstrate substantial promise for non-contrast pulmonary angiography and detailed

  10. The role of N7 protonation of guanine in determining the structure, stability and function of RNA base pairs.

    PubMed

    Halder, Antarip; Bhattacharya, Sohini; Datta, Ayan; Bhattacharyya, Dhananjay; Mitra, Abhijit

    2015-10-21

    The roles of protonated nucleobases in stabilizing different structural motifs and in facilitating catalytic functions of RNA are well known. Among different polar sites of all the nucleobases, N7 of guanine has the highest protonation propensity at physiological pH. However, unlike other easily protonable sites such as N1 and N3 of adenine or N3 of cytosine, N7 protonation of guanine does not lead to the stabilization of base pairs involving its protonated Hoogsteen edge. It also does not facilitate its participation in any acid-base catalysis process. To explore the possible roles of N7 protonated guanine, we have studied its base pairing potentials involving WatsonCrick and sugar edges, which undergo major charge redistribution upon N7 protonation. We have carried out quantum chemical geometry optimization at the M05-2X/6-311G+(2d,2p) level, followed by interaction energy calculation at the MP2/aug-cc-pVDZ level, along with the analysis of the context of occurrence for selected base pairs involving the sugar edge or the WatsonCrick edge of guanine within a non-redundant set of 167 RNA crystal structures. Our results suggest that, four base pairs - G:C W:W trans, G:rC W:S cis, G:G W:H cis and G:G S:H trans may involve N7 protonated guanine. These base pairs deviate significantly from their respective experimental geometries upon QM optimization, but they retain their experimental geometries if guanine N7 protonation is considered during optimization. Our study also reveals the role of guanine N7 protonation (i) in stabilizing important RNA structural motifs, (ii) in providing a framework for designing pH driven molecular motors and (iii) in providing an alternative strategy to mimic the effect of post-transcriptional changes. PMID:26382322

  11. Measurement of the proton structure function F2 at very low Q2 at HERA

    NASA Astrophysics Data System (ADS)

    Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M. C. K.; Abbiendi, G.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Coppola, N.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Paul, E.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wieber, H.; Bailey, D. S.; Barret, O.; Brook, N. H.; Foster, B.; Heath, G. P.; Heath, H. F.; McFall, J. D.; Piccioni, D.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Piotrzkowski, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Kotański, A.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Burgard, C.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hasell, D.; Hebbel, K.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Lindemann, L.; Löhr, B.; Martínez, M.; Milite, M.; Monteiro, T.; Moritz, M.; Notz, D.; Pelucchi, F.; Petrucci, M. C.; Rohde, M.; Saull, P. R. B.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Tassi, E.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Straub, P. B.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Benen, A.; Eisenhardt, S.; Markun, P.; Raach, H.; Wölfle, S.; Bussey, P. J.; Bell, M.; Doyle, A. T.; Lee, S. W.; Lupi, A.; Macdonald, N.; McCance, G. J.; Saxon, D. H.; Sinclair, L. E.; Skillicorn, I. O.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Garfagnini, A.; Gialas, I.; Gladilin, L. K.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Zetsche, F.; Goncalo, R.; Long, K. R.; Miller, D. B.; Tapper, A. D.; Walker, R.; Mallik, U.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Park, I. H.; Son, D.; Barreiro, F.; García, G.; Glasman, C.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Barbi, M.; Corriveau, F.; Hanna, D. S.; Ochs, A.; Padhi, S.; Riveline, M.; Stairs, D. G.; Wing, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, M.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Y. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Y.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Schagen, S.; van Sighem, A.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Große-Knetter, J.; Matsushita, T.; Quadt 11, A.; Ruske, O.; Sutton, M. R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dosselli, U.; Dusini, S.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Turcato, M.; Voci, C.; Adamczyk, L.; Iannotti, L.; Oh, B. Y.; Okrasiński, J. R.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Pavel, N.; Abramowicz, H.; Dagan, S.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sabetfakhri, A.; Simmons, D.; Butterworth, J. M.; Catterall, C. D.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Z˙arnecki, A. F.; Adamus, M.; Gadaj, T.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Foudas, C.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wildschek, T.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Catterall, C.; Cole, J. E.; Frisken, W. R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.

    2000-08-01

    A measurement of the proton structure function F2(x,Q2) is presented in the kinematic range 0.045GeV2

  12. Structural Basis for the Function and Inhibition of an Influenze Virus Proton Channel

    SciTech Connect

    Stouffer,A.; Acharya, R.; Salom, D.; Levine, A.; Di Costanzo, L.; Soto, C.; Tershko, V.; Nanda, V.; Stayrook, S.; DeGrado, W.

    2008-01-01

    The M2 protein from influenza A virus is a pH-activated proton channel that mediates acidification of the interior of viral particles entrapped in endosomes. M2 is the target of the anti-influenza drugs amantadine and rimantadine; recently, resistance to these drugs in humans, birds and pigs has reached more than 90% (ref. 1). Here we describe the crystal structure of the transmembrane-spanning region of the homotetrameric protein in the presence and absence of the channel-blocking drug amantadine. pH-dependent structural changes occur near a set of conserved His and Trp residues that are involved in proton gating2. The drug-binding site is lined by residues that are mutated in amantadine-resistant viruses3, 4. Binding of amantadine physically occludes the pore, and might also perturb the pKa of the critical His residue. The structure provides a starting point for solving the problem of resistance to M2-channel blockers.

  13. The Structure of the Proton

    DOE R&D Accomplishments Database

    Chambers, E. E.; Hofstadter, R.

    1956-04-01

    The structure and size of the proton have been studied by means of the methods of high-energy electron scattering. The elastic scattering of electrons from protons in polyethylene has been investigated at the following energies in the laboratory system: 200, 300, 400, 500, 550 Mev. The range of laboratory angles examined has been 30 degrees to 135 degrees. At the largest angles and the highest energy, the cross section for scattering shows a deviation below that expected from a point proton by a factor of about nine. The magnitude and variation with angle of the deviations determine a structure factor for the proton, and thereby determine the size and shape of the charge and magnetic-moment distributions within the proton. An interpretation, consistent at all energies and angles and agreeing with earlier results from this laboratory, fixes the rms radius at 0.77 {plus or minus} 0.10 x 10{sup -13} cm for each of the charge and moment distributions. The shape of the density function is not far from a Gaussian with rms radius 0.70 x 10{sup -13} cm or an exponential with rms radius 0.80 x 10 {sup -13} cm. An equivalent interpretation of the experiments would ascribe the apparent size to a breakdown of the Coulomb law and the conventional theory of electromagnetism.

  14. Measurement of the proton structure function F2 at low Q2 in QED Compton scattering at HERA

    NASA Astrophysics Data System (ADS)

    Aktas, A.; Andreev, V.; Anthonis, T.; Asmone, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Berndt, T.; Bizot, J. C.; Böhme, J.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brisson, V.; Bröker, H.-B.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Chekelian, V.; Collard, C.; Contreras, J. G.; Coppens, Y. R.; Coughlan, J. A.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E. A.; Diaconu, C.; Dingfelder, J.; Dodonov, V.; Dubak, A.; Duprel, C.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Flügge, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garutti, E.; Garvey, J.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gorbounov, S.; Grab, C.; Grässler, H.; Greenshaw, T.; Gregori, M.; Grindhammer, G.; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Heremans, R.; Herrera, G.; Herynek, I.; Heuer, R.-D.; Hildebrandt, M.; Hiller, K. H.; Höting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keller, N.; Kennedy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Koblitz, B.; Korbel, V.; Kostka, P.; Koutouev, R.; Kropivnitskaya, A.; Kroseberg, J.; Kückens, J.; Kuhr, T.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebedev, A.; Leißner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lueders, H.; Lüke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marks, J.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Michine, S.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morozov, I.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Ossoskov, G.; Ozerov, D.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Plačakytė, R.; Pöschl, R.; Portheault, B.; Povh, B.; Raicevic, N.; Ratiani, Z.; Reimer, P.; Reisert, B.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Scheins, J.; Schilling, F.-P.; Schleper, P.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Uraev, A.; Urban, M.; Usik, A.; Utkin, D.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Winter, G.-G.; Wissing, Ch.; Woehrling, E.-E.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zohrabyan, H.; Zomer, F.; H1 Collaboration

    2004-09-01

    The proton structure function F2 (x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q2, down to 0.5 GeV2, and Bjorken x up to ∼0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton-nucleon scattering experiments.

  15. Proposal to measure spin-structure functions and semi-exclusive asymmetries for the proton and neutron at HERA

    SciTech Connect

    Jackson, H.E.; Hansen, J.O.; Jones, C.E.

    1995-08-01

    Nucleon spin physics will be studied in the HERMES experiment, that will use polarized internal targets of essentially pure atomic H, D, and {sup 3}He in the HERA electron storage ring at DESY. A series of measurements of spin-dependent properties of the nucleon and few-body nuclei will be made; the spin structure function g{sub 1}(x) of the proton and neutron will be measured to test the Bjorken sum rule and study the fraction of the nucleon spin carried by quarks; the spin structure function g{sub 2}W, sensitive to quark-gluon correlations, and the structure functions b{sub 1}(x), and {Delta}(x), sensitive to nuclear binding effects, will be measured; and, using the particle identification capability of the HERMES detector, pions will be detected in coincidence with the scattered electrons. The coincident hadron measurements represent the most important extension that can be made at this time to the existing measurements on the nucleon spin structure functions because they provide information about the flavor-dependence of the quark spin distribution in the nucleon. Argonne is providing the Cerenkov counter to be used for particle identification and developing the drifilm coating technique for the ultrathin target cell required for this experiment. The HERMES collaboration intends to use polarized targets with the highest available figures of merit, and the Argonne laser-driven source offers the most promise for a significant advance in present-day targets.

  16. Proton-Proton Elastic Scattering Excitation Functions at Intermediate Energies

    SciTech Connect

    Bisplinghoff, J.; Daniel, R.; Diehl, O.; Engelhardt, H.; Ernst, J.; Eversheim, P.; Gro-Hardt, R.; Heider, S.; Heine, A.; Hinterberger, F.; Jahn, R.; Jeske, M.; Lahr, U.; Maschuw, R.; Mayer-Kuckuk, T.; Mosel, F.; Rohdje, H.; Rosendaal, D.; Ro, U.; Scheid, H.; Schulz-Rojahn, M.; Schwandt, F.; Schwarz, V.; Trelle, H.; Wiedmann, W.; Ziegler, R.; Albers, D.; Bollmann, R.; Bueer, K.; Dohrmann, F.; Gasthuber, M.; Greiff, J.; Gro, A.; Igelbrink, M.; Langkau, R.; Lindlein, J.; Mueller, M.; Muenstermann, M.; Schirm, N.; Scobel, W.; Wellinghausen, A.; Woller, K.; Cloth, P.; Gebel, R.; Maier, R.; Prasuhn, D.; von Rossen, P.; Sterzenbach, G.

    1997-03-01

    Excitation functions of proton-proton elastic scattering cross sections have been measured in narrow steps for projectile momenta p{sub p} (energies T{sub p}) from 1100 to 3300MeV/c (500 to 2500MeV) in the angular range 35{degree}{le}{Theta}{sub c.m.}{le}90{degree} with a detector providing {Delta}{Theta}{sub c.m.}{approx}1.4{degree} resolution. Measurements have been performed continuously during projectile acceleration in the cooler synchrotron COSY with an internal CH{sub 2} fiber target, taking particular care to monitor luminosity as a function of T{sub p}. The advantages of this experimental technique are demonstrated, and the excitation functions obtained are compared to existing cross section data. No evidence for narrow structures was found. {copyright} {ital 1997} {ital The American Physical Society}

  17. Precision Measurement of the Proton and Deuteron Spin Structure Functions g2

    SciTech Connect

    Rock, Stephen E.

    2003-02-27

    We measured the spin structure functions g{sub 2}{sup p} and g{sub 2}{sup d} in the range 0.02 {le} x {le} 0.8 and 0.7 {le} Q{sup 2} {le} 20 GeV{sup 2} by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH{sub 3} and {sup 6}LiD targets. g{sub 2} approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d{sub 2}{sup p} and d{sub 2}{sup m} are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule if there is no pathological behavior as x {yields} 0. The Efremov-Leader-Teryaev integral is consistent with zero.

  18. The spin structure function g1p of the proton and a test of the Bjorken sum rule

    NASA Astrophysics Data System (ADS)

    Adolph, C.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Austregesilo, A.; Azevedo, C.; Badełek, B.; Balestra, F.; Barth, J.; Baum, G.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chang, W.-C.; Chiosso, M.; Choi, I.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S. V.; Doshita, N.; Duic, V.; Dziewiecki, M.; Efremov, A.; Eversheim, P. D.; Eyrich, W.; Ferrero, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse-Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F. H.; Herrmann, F.; Hinterberger, F.; Horikawa, N.; d'Hose, N.; -Yu Hsieh, C.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jörg, P.; Joosten, R.; Kabuß, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kuchinski, N.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Marchand, C.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neyret, D.; Nikolaenko, V. I.; Novy, J.; Nowak, W.-D.; Nunes, A. S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pesek, M.; Peshekhonov, D. V.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Rocco, E.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Rychter, A.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Selyunin, A.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

    2016-02-01

    New results for the double spin asymmetry A1p and the proton longitudinal spin structure function g1p are presented. They were obtained by the COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH3 target. The data were collected in 2011 and complement those recorded in 2007 at 160 GeV, in particular at lower values of x. They improve the statistical precision of g1p (x) by about a factor of two in the region x ≲ 0.02. A next-to-leading order QCD fit to the g1 world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, ΔΣ, ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of g1p. The uncertainty of ΔΣ is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function g1NS (x ,Q2) yields as ratio of the axial and vector coupling constants |gA /gV | = 1.22 ± 0.05 (stat.) ± 0.10 (syst.), which validates the sum rule to an accuracy of about 9%.

  19. The proton-linked monocarboxylate transporter (MCT) family: structure, function and regulation.

    PubMed Central

    Halestrap, A P; Price, N T

    1999-01-01

    Monocarboxylates such as lactate and pyruvate play a central role in cellular metabolism and metabolic communication between tissues. Essential to these roles is their rapid transport across the plasma membrane, which is catalysed by a recently identified family of proton-linked monocarboxylate transporters (MCTs). Nine MCT-related sequences have so far been identified in mammals, each having a different tissue distribution, whereas six related proteins can be recognized in Caenorhabditis elegans and 4 in Saccharomyces cerevisiae. Direct demonstration of proton-linked lactate and pyruvate transport has been demonstrated for mammalian MCT1-MCT4, but only for MCT1 and MCT2 have detailed analyses of substrate and inhibitor kinetics been described following heterologous expression in Xenopus oocytes. MCT1 is ubiquitously expressed, but is especially prominent in heart and red muscle, where it is up-regulated in response to increased work, suggesting a special role in lactic acid oxidation. By contrast, MCT4 is most evident in white muscle and other cells with a high glycolytic rate, such as tumour cells and white blood cells, suggesting it is expressed where lactic acid efflux predominates. MCT2 has a ten-fold higher affinity for substrates than MCT1 and MCT4 and is found in cells where rapid uptake at low substrate concentrations may be required, including the proximal kidney tubules, neurons and sperm tails. MCT3 is uniquely expressed in the retinal pigment epithelium. The mechanisms involved in regulating the expression of different MCT isoforms remain to be established. However, there is evidence for alternative splicing of the 5'- and 3'-untranslated regions and the use of alternative promoters for some isoforms. In addition, MCT1 and MCT4 have been shown to interact specifically with OX-47 (CD147), a member of the immunoglobulin superfamily with a single transmembrane helix. This interaction appears to assist MCT expression at the cell surface. There is still

  20. Functional polymers for anhydrous proton transport

    NASA Astrophysics Data System (ADS)

    Chikkannagari, Nagamani

    Anhydrous proton conducting polymers are highly sought after for applications in high temperature polymer electrolyte membrane fuel cells (PEMFCs). N-heterocycles (eg. imidazole, triazole, and benzimidazole), owing to their amphoteric nature, have been widely studied to develop efficient anhydrous proton transporting polymers. The proton conductivity of N-heterocyclic polymers is influenced by several factors and the design and development of polymers with a delicate balance among various synergistic and competing factors to provide appreciable proton conductivities has been a challenging task. In this thesis, the proton transport (PT) characteristics of polymers functionalized with two diverse classes of functional groups--- N-heterocycles and phenols have been investigated and efforts have been made to develop the molecular design criteria for the design and development of efficient proton transporting functional groups and polymers. The proton conduction pathway in 1H-1,2,3-triazole polymers is probed by employing structurally analogous N-heterocyclic (triazole, imidazole, and pyrazole) and benz-N-heterocyclic (benzotriazole, benzimidazole, and benzopyrazole) polymers. Imidazole-like pathway was found to dominate the proton conductivity of triazole and pyrazole-like pathway makes only a negligible contribution, if any. Polymers containing benz-N-heterocycles exhibited higher proton conductivity than those with the corresponding N-heterocycles. Pyrazole-like functional groups, i.e. the molecules with two nitrogen atoms adjacent to each other, were found not to be good candidates for PT applications. A new class of proton transporting functional groups, phenols, has been introduced for anhydrous PT. One of the highlighting features of phenols over N-heterocycles is that the hydrogen bond donor/acceptor reorientation can happen on a single -OH site, allowing for facile reorientational dynamics in Grotthuss PT and enhanced proton conductivities in phenolic polymers

  1. Measurement of the proton structure function F2 and σγ*ptot at low Q2 and very low x at HERA

    NASA Astrophysics Data System (ADS)

    Breitweg, J.; Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Yoshida, R.; Zhang, H.; Mattingly, M. C. K.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Romeo, G. Cara; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; de Pasquale, S.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Ricci, F.; Sartorelli, G.; Garcia, Y. Zamora; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Eckert, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Kerger, R.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Stamm, J.; Wedemeyer, R.; Wieber, H.; Bailey, D. S.; Campbell-Robson, S.; Cottingham, W. N.; Foster, B.; Hall-Wilton, R.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Pac, M. Y.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Mellado, B.; Parsons, J. A.; Ritz, S.; Sampson, S.; Sciulli, F.; Straub, P. B.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Jakubowski, Z.; Przybycień, M. B.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, J.; Kisielewska, D.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajac, J.; Duliński, Z.; Kotański, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Fricke, U.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Haas, T.; Hain, W.; Hasell, D.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Lindemann, L.; Löhr, B.; Löwe, M.; Mańczak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Park, I. H.; Pellegrino, A.; Pelucchi, F.; Piotrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Ryan, J. J.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Surrow, B.; Tassi, E.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Żarnecki, A. F.; Zeuner, W.; Burow, B. D.; Grabosch, H. J.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Sinclair, L. E.; Strickland, E.; Utley, M. L.; Waugh, R.; Wilson, A. S.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Gladilin, L. K.; Horstmann, D.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Cole, J. E.; Harris, V. L.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Whitfield, A. F.; Mallik, U.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; Fleck, J. I.; Ishii, T.; Kuze, M.; Nakao, M.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; An, S. H.; Lee, S. B.; Nam, S. W.; Park, H. S.; Park, S. K.; Barreiro, F.; Fernández, J. P.; García, G.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martínez, M.; del Peso, J.; Puga, J.; Terrón, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Murray, W. N.; Ochs, A.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Yu. A.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Chlebana, F.; Engelen, J.; Kooijman, P.; van Sighem, A.; Tiecke, H.; Tuning, N.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Romanowski, T. A.; Blaikley, H. E.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Edmonds, J. K.; Harnew, N.; Lancaster, M.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Ruske, O.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Bertolin, A.; Brugnera, R.; Carlin, R.; dal Corso, F.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Feild, R. G.; Oh, B. Y.; Okrasiński, J. R.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Raso, M.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Schwarzer, O.; Walenta, A. H.; Abramowicz, H.; Briskin, G.; Dagan, S.; Doeker, T.; Kananov, S.; Levy, A.; Abe, T.; Fusayasu, T.; Inuzuka, M.; Nagano, K.; Suzuki, I.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Petrucci, M. C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Brkic, M.; Fagerstroem, C.-P.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Sutton, M. R.; Lu, B.; Mo, L. W.; Ciborowski, J.; Grzelak, G.; Kasprzak, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Revel, D.; Badgett, W. F.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Bhadra, S.; Frisken, W. R.; Khakzad, M.; Schmidke, W. B.

    1997-02-01

    A small electromagnetic sampling calorimeter, installed in the ZEUS experiment in 1995, significantly enhanced the acceptance for very low x and low Q2 inelastic neutral current scattering, e+p -> e+X, at HERA. A measurement of the proton structure function F2 and the total virtual photon-proton (γ*p) cross-section is presented for 0.11 <= Q2 <= 0.65 GeV2 and 2 × 10-6 <= x <= 6 × 10-5, corresponding to a range in the γ*p c.m. energy of 100 <= W <= 230 GeV. Comparisons with various models are also presented.

  2. Chemistry as a function of the fine-structure constant and the electron-proton mass ratio

    NASA Astrophysics Data System (ADS)

    King, Rollin A.; Siddiqi, Ali; Allen, Wesley D.; Schaefer, Henry F., III

    2010-04-01

    In standard computations in theoretical quantum chemistry the accepted values of the fundamental physical constants are assumed. Alternatively, the tools of computational quantum chemistry can be used to investigate hypothetical chemistry that would result from different values of these constants, given the same physical laws. In this work, the dependence of a variety of basic chemical quantities on the values of the fine-structure constant and the electron-proton mass ratio is explored. In chemistry, the accepted values of both constants may be considered small, in the sense that their increase must be substantial to seriously impact bond energies. It is found that if the fine-structure constant were larger, covalent bonds between light atoms would be weaker, and the dipole moment and hydrogen-bonding ability of water would be reduced. Conversely, an increase in the value of the electron-proton mass ratio increases dissociation energies in molecules such as H2, O2, and CO2. Specifically, a sevenfold increase in the fine-structure constant decreases the strength of the O-H bond in the water molecule by 7 kcal mol-1 while reducing its dipole moment by at least 10%, whereas a 100-fold increase in the electron-proton mass ratio increases the same bond energy by 11 kcal mol-1.

  3. Anatomy of the differential gluon structure function of the proton from the experimental data on F2p(x,Q2)

    NASA Astrophysics Data System (ADS)

    Ivanov, I. P.; Nikolaev, N. N.

    2002-03-01

    The differential gluon structure function of the proton F(x,Q2) introduced by Fadin, Kuraev, and Lipatov in 1975 is used in many applications of small-x QCD. We report here ready-to-use parametrizations of F(x,Q2) from the κ-factorization phenomenology of the experimental data on the small-x proton structure function F2p(x,Q2). These parametrizations are based partly on the available Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution fits [Glück-Reya-Vogt, Coordinated Theoretical/Experimental Project on QCD Phenomenology (CTEQ), and Martin-Roberts-Stirling] to parton distribution functions and on realistic extrapolations into a soft region. We discuss the impact of soft gluons on various observables. The x dependence of the F(x,Q2) so determined varies strongly with Q2 and does not exhibit simple Regge properties. Nonetheless, the hard-to-soft diffusion is found to give rise to a viable approximation of the proton structure function F2p(x,Q2) by the soft and hard Regge components with intercepts Δsoft=0 and Δhard~0.4.

  4. Structural investigation of protonated azidothymidine and protonated dimer.

    PubMed

    Ziegler, Blake E; Marta, Rick A; Burt, Michael B; Martens, Sabrina M; Martens, Jonathan K; McMahon, Terry B

    2014-02-01

    Infrared multiple photon dissociation (IRMPD) spectroscopy experiments and quantum chemical calculations have been used to explore the possible structures of protonated azidothymidine and the corresponding protonated dimer. Many interesting differences between the protonated and neutral forms of azidothymidine were found, particularly associated with keto-enol tautomerization. Comparison of computational vibrational and the experimental IMRPD spectra show good agreement and give confidence that the dominant protonated species has been identified. The protonated dimer of azidothymidine exhibits three intramolecular hydrogen bonds. The IRMPD spectrum of the protonated dimer is consistent with the spectrum of the most stable computational structure. This work brings to light interesting keto-enol tautomerization and exocyclic hydrogen bonding involving azidothymidine and its protonated dimer. The fact that one dominant protonated species is observed in the gas phase, despite both the keto and enol structures being similar in energy, is proposed to be the direct result of the electrospray ionization process in which the dominant protonated dimer structure dissociates in the most energetically favorable way. PMID:24306778

  5. Transmembrane Communication: General Principles and Lessons from the Structure and Function of the M2 Proton Channel, K+ Channels, and Integrin Receptors

    PubMed Central

    Grigoryan, Gevorg; Moore, David T.; DeGrado, William F.

    2013-01-01

    Signal transduction across biological membranes is central to life. This process generally happens through communication between different domains and hierarchical coupling of information. Here, we review structural and thermodynamic principles behind transmembrane (TM) signal transduction and discuss common themes. Communication between signaling domains can be understood in terms of thermodynamic and kinetic principles, and complex signaling patterns can arise from simple wiring of thermodynamically coupled domains. We relate this to functions of several signal transduction systems: the M2 proton channel from influenza A virus, potassium channels, integrin receptors, and bacterial kinases. We also discuss key features in the structural rearrangements responsible for signal transduction in these systems. PMID:21548783

  6. Structural and Functional Studies of a Newly Grouped Haloquadratum walsbyi Bacteriorhodopsin Reveal the Acid-resistant Light-driven Proton Pumping Activity*

    PubMed Central

    Hsu, Min-Feng; Fu, Hsu-Yuan; Cai, Chun-Jie; Yi, Hsiu-Pin; Yang, Chii-Shen; Wang, Andrew H.-J.

    2015-01-01

    Retinal bound light-driven proton pumps are widespread in eukaryotic and prokaryotic organisms. Among these pumps, bacteriorhodopsin (BR) proteins cooperate with ATP synthase to convert captured solar energy into a biologically consumable form, ATP. In an acidic environment or when pumped-out protons accumulate in the extracellular region, the maximum absorbance of BR proteins shifts markedly to the longer wavelengths. These conditions affect the light-driven proton pumping functional exertion as well. In this study, wild-type crystal structure of a BR with optical stability under wide pH range from a square halophilic archaeon, Haloquadratum walsbyi (HwBR), was solved in two crystal forms. One crystal form, refined to 1.85 Å resolution, contains a trimer in the asymmetric unit, whereas another contains an antiparallel dimer was refined at 2.58 Å. HwBR could not be classified into any existing subgroup of archaeal BR proteins based on the protein sequence phylogenetic tree, and it showed unique absorption spectral stability when exposed to low pH values. All structures showed a unique hydrogen-bonding network between Arg82 and Thr201, linking the BC and FG loops to shield the retinal-binding pocket in the interior from the extracellular environment. This result was supported by R82E mutation that attenuated the optical stability. The negatively charged cytoplasmic side and the Arg82–Thr201 hydrogen bond may play an important role in the proton translocation trend in HwBR under acidic conditions. Our findings have unveiled a strategy adopted by BR proteins to solidify their defenses against unfavorable environments and maintain their optical properties associated with proton pumping. PMID:26483542

  7. Structural and Functional Studies of a Newly Grouped Haloquadratum walsbyi Bacteriorhodopsin Reveal the Acid-resistant Light-driven Proton Pumping Activity.

    PubMed

    Hsu, Min-Feng; Fu, Hsu-Yuan; Cai, Chun-Jie; Yi, Hsiu-Pin; Yang, Chii-Shen; Wang, Andrew H-J

    2015-12-01

    Retinal bound light-driven proton pumps are widespread in eukaryotic and prokaryotic organisms. Among these pumps, bacteriorhodopsin (BR) proteins cooperate with ATP synthase to convert captured solar energy into a biologically consumable form, ATP. In an acidic environment or when pumped-out protons accumulate in the extracellular region, the maximum absorbance of BR proteins shifts markedly to the longer wavelengths. These conditions affect the light-driven proton pumping functional exertion as well. In this study, wild-type crystal structure of a BR with optical stability under wide pH range from a square halophilic archaeon, Haloquadratum walsbyi (HwBR), was solved in two crystal forms. One crystal form, refined to 1.85 Å resolution, contains a trimer in the asymmetric unit, whereas another contains an antiparallel dimer was refined at 2.58 Å. HwBR could not be classified into any existing subgroup of archaeal BR proteins based on the protein sequence phylogenetic tree, and it showed unique absorption spectral stability when exposed to low pH values. All structures showed a unique hydrogen-bonding network between Arg(82) and Thr(201), linking the BC and FG loops to shield the retinal-binding pocket in the interior from the extracellular environment. This result was supported by R82E mutation that attenuated the optical stability. The negatively charged cytoplasmic side and the Arg(82)-Thr(201) hydrogen bond may play an important role in the proton translocation trend in HwBR under acidic conditions. Our findings have unveiled a strategy adopted by BR proteins to solidify their defenses against unfavorable environments and maintain their optical properties associated with proton pumping. PMID:26483542

  8. Moments of the longitudinal proton structure function FL from global data in the Q(2) range 0.75-45.0  (GeV/c)(2).

    PubMed

    Monaghan, P; Accardi, A; Christy, M E; Keppel, C E; Melnitchouk, W; Zhu, L

    2013-04-12

    We present an extraction of the lowest three moments of the proton longitudinal structure function FL from world data between Q(2)=0.75 and 45  (GeV/c)(2). The availability of new FL data at low Bjorken x from HERA and at large x from Jefferson Lab allows the first determination of these moments over a large Q(2) range, relatively free from uncertainties associated with extrapolations into unmeasured regions. The moments are found to be underestimated by leading twist structure function parametrizations, especially for the higher moments, suggesting either the presence of significant higher twist effects in FL and/or a larger gluon distribution at high x. PMID:25167253

  9. Spin structure of the proton

    SciTech Connect

    Nathan Isgur

    1995-08-01

    In these lectures the author argues that their response to the spin crisis should not be to abandon the naive quark model baby, but rather to allow it to mature. He begin by recalling what a beautiful baby the quark model is via an overview of its successes in spectroscopy, dynamics, and valence spin structure. He also introduces the conservative hypothesis that dynamical q{anti q} pairs are its key missing ingredient. He then discusses dressing the baby. He first shows that it can be clothed in glue without changing its spectroscopic successes. In the process, several dynamical mysteries associated with quark model spectroscopy are potentially explained. Next, he dresses the baby in q{anti q} pairs, first showing that this can be done without compromising the naive quark model's success with either spectroscopy or the OZI rule. Finally, he shows that despite their near invisibility elsewhere, pairs do play an important role in the proton's spin structure by creating an antipolarized q{anti q} sea. In the context of an explicit calculation he demonstrate that it is plausible that the entire ''spin crisis'' arises from this effect.

  10. Proton Spin Structure in the Resonance Region

    SciTech Connect

    F. R. Wesselmann; K. Slifer; S. Tajima; A. Aghalaryan; A. Ahmidouch; R. Asaturyan; F. Bloch; W. Boeglin; P. Bosted; C. Carasco; R. Carlini; J. Cha; J. P. Chen; M. E. Christy; L. Cole; L. Coman; D. Crabb; S. Danagoulian; D. Day; J. Dunne; M. Elaasar; R. Ent; H. Fenker; E. Frlez; L. Gan; D. Gaskell; J. Gomez; B. Hu; M. K. Jones; J. Jourdan; C. Keith; C. E. Keppel; M. Khandaker; A. Klein; L. Kramer; Y. Liang; J. Lichtenstadt; R. Lindgren; D. Mack; P. McKee; D. McNulty; D. Meekins; H. Mkrtchyan; R. Nasseripour; I. Niculescu; K. Normand; B. Norum; D. Pocanic; Y. Prok; B. Raue; J. Reinhold; J. Roche; D. Rohe; O. A. Rondon; N. Savvinov; B. Sawatzky; M. Seely; I. Sick; C. Smith; G. Smith; S. Stepanyan; L. Tang; G. Testa; W. Vulcan; K. Wang; G. Warren; S. Wood; C. Yan; L. Yuan; Junho Yun; Markus Zeier; Hong Guo Zhu

    2006-10-11

    The RSS collaboration has measured the spin structure functions g{sub 1} and g{sub 2} of the proton at Jefferson Lab using the lab's polarized electron beam, the Hall C HMS spectrometer and the UVa polarized solid target. The asymmetries A{sub parallel} and A{sub perp} were measured at the elastic peak and in the region of the nucleon resonances (1.085 GeV < W < 1.910 GeV) at an average four momentum transfer of Q{sup 2} = 1.3 GeV{sup 2}. The extracted spin structure functions and their kinematic dependence make a significant contribution in the study of higher-twist effects and polarized duality tests.

  11. Measurement of the proton structure function F2 and of the total photon-proton cross section σ totγ ∗p at very low Q2 and very low x

    NASA Astrophysics Data System (ADS)

    Amelung, Christoph; ZEUS Collaboration

    1999-10-01

    The proton structure function F2 has been measured in the range 0.045 GeV 2 < Q2 < 0.65 GeV 2and 6·10 -7 < ξ < 1·10 -3 using 3.9 pb -1 of ep → eX reactions recorded with the ZEUS detector in 1997. The analysis is based on data from the Beam Pipe Calorimeter (BPC) and the Beam Pipe Tracker (BPT). Compared to our previous analysis, the BPT permits improved background suppression and better control of systematic uncertainties, allowing the extension of the kinematic region of the measurement towards lower Q2 as well as higher and lower y. Significant improvements have also been achieved in the simulation of the hadronic final state via a mixture of samples of non-diffractive and diffractive Monte Carlo events, generated by the programs DJANGO and RAPGAP.

  12. Structural Changes and Proton Transfer in Cytochrome c Oxidase

    PubMed Central

    Vilhjálmsdóttir, Jóhanna; Johansson, Ann-Louise; Brzezinski, Peter

    2015-01-01

    In cytochrome c oxidase electron transfer from cytochrome c to O2 is linked to transmembrane proton pumping, which contributes to maintaining a proton electrochemical gradient across the membrane. The mechanism by which cytochrome c oxidase couples the exergonic electron transfer to the endergonic proton translocation is not known, but it presumably involves local structural changes that control the alternating proton access to the two sides of the membrane. Such redox-induced structural changes have been observed in X-ray crystallographic studies at residues 423–425 (in the R. sphaeroides oxidase), located near heme a. The aim of the present study is to investigate the functional effects of these structural changes on reaction steps associated with proton pumping. Residue Ser425 was modified using site-directed mutagenesis and time-resolved spectroscopy was used to investigate coupled electron-proton transfer upon reaction of the oxidase with O2. The data indicate that the structural change at position 425 propagates to the D proton pathway, which suggests a link between redox changes at heme a and modulation of intramolecular proton-transfer rates. PMID:26310633

  13. Understanding the proton's spin structure

    SciTech Connect

    Fred Myhrer; Thomas, Anthony W.

    2010-02-01

    We discuss the tremendous progress that has been towards an understanding of how the spin of the proton is distributed on its quark and gluon constituents. This is a problem that began in earnest twenty years ago with the discovery of the proton "spin crisis" by the European Muon Collaboration. The discoveries prompted by that original work have given us unprecedented insight into the amount of spin carried by polarized gluons and the orbital angular momentum of the quarks.

  14. Proton transport and cell function.

    PubMed Central

    Ives, H E; Rector, F C

    1984-01-01

    The past five years have witnessed an explosion of information on the many and varied roles of H+ transport in cell function. H+ transport is involved in three broad areas of cell function: (a) maintenance and alteration of intracellular pH for initiation of specific cellular events, (b) generation of pH gradients in localized regions of the cell, including gradients involved in energy transduction, and (c) transepithelial ion transport. These processes each involve one or more of several H+ translocating mechanisms. The first section of this review will discuss these H+ translocating mechanisms and the second part will deal with the cellular functions controlled by H+ transport. PMID:6321552

  15. Precision Measurement of the Proton and Deuteron Spin Structure Functions g{sub 2} and Asymmetry A{sub 2}

    SciTech Connect

    Rock, Stephen

    2002-04-24

    We have measured the spin structure functions g{sub 2}{sup p} and g{sub 2}{sup d} and the virtual photon asymmetries A{sub 2}{sup p} and A{sub 2}{sup d} over the kinematic range 0.02 {le} x {le} 0.8 and 0.7 {le} Q{sup 2} {le} 20 GeV{sup 2} by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH{sub 3} and {sup 6}LiD targets. Our measured g{sub 2} approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d{sub 2}{sup p} and d{sub 2}{sup n} are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule if there is no pathological behavior as x {yields} 0. The Efremov-Leader-Teryaev integral is consistent with zero within our measured kinematic range. The absolute value of A{sub 2} is significantly smaller than the A{sub 2} < {radical}(R(1+A{sub 1})/2) limit.

  16. Crystal structure of the plasma membrane proton pump.

    PubMed

    Pedersen, Bjørn P; Buch-Pedersen, Morten J; Morth, J Preben; Palmgren, Michael G; Nissen, Poul

    2007-12-13

    A prerequisite for life is the ability to maintain electrochemical imbalances across biomembranes. In all eukaryotes the plasma membrane potential and secondary transport systems are energized by the activity of P-type ATPase membrane proteins: H+-ATPase (the proton pump) in plants and fungi, and Na+,K+-ATPase (the sodium-potassium pump) in animals. The name P-type derives from the fact that these proteins exploit a phosphorylated reaction cycle intermediate of ATP hydrolysis. The plasma membrane proton pumps belong to the type III P-type ATPase subfamily, whereas Na+,K+-ATPase and Ca2+-ATPase are type II. Electron microscopy has revealed the overall shape of proton pumps, however, an atomic structure has been lacking. Here we present the first structure of a P-type proton pump determined by X-ray crystallography. Ten transmembrane helices and three cytoplasmic domains define the functional unit of ATP-coupled proton transport across the plasma membrane, and the structure is locked in a functional state not previously observed in P-type ATPases. The transmembrane domain reveals a large cavity, which is likely to be filled with water, located near the middle of the membrane plane where it is lined by conserved hydrophilic and charged residues. Proton transport against a high membrane potential is readily explained by this structural arrangement. PMID:18075595

  17. Tests of proton structure functions using leptons at CDF and DØ: W charge asymmetry and Drell-Yan production

    NASA Astrophysics Data System (ADS)

    Barbaro, Pawel de

    1996-02-01

    High statistics W charge asymmetry measurements at the Tevatron p¯p collider significantly constrain the u and d quark distributions, and specifically the slope of the d(x)/u(x) in the x range 0.007 to 0.27. We present measurements of the lepton charge asymmetry as a function of lepton rapidity, A(yl) at √s=1.8 TeV for ‖yl‖<2.0, for W decays to electrons and muons recorded by the CDF detector during the 1992-93 run (≊20 pb-1), and the first ≊50 pb-1 of data from the 1994-95 run. These precise data make possible further discrimination between sets of modern parton distributions. In particular it is found that the most recent parton distributions, which included the CDF 1992-93 W asymmetry data in their fits (MRSA, CTEQ3M and GRV94) are still in good agreement with the more precise data from the 1994-95 run. W charge asymmetry results from DO/ based on ≊6.5 pb-1 of data from the 1992-93 run and ≊29.7 pb-1 of data from the 1994-1995 run, using the W decays to muons, are also presented and are found to be consistent with CDF results. In addition, we present preliminary measurement of the Drell-Yan cross-section by CDF using a dielectron sample collected during the 1993-94 run (≊20 pb-1) and a high mass dimuon sample from the combined 1993-94 and 1994-95 runs (≊70 pb-1). The measurement is in good agreement with predictions using the most recent parton density functions in a dilepton mass range between 11 and 350 GeV/c2.

  18. Tests of proton structure functions using leptons at CDF and DO/: {ital W} charge asymmetry and Drell-Yan production

    SciTech Connect

    Barbaro, P.d.

    1996-02-01

    High statistics {ital W} charge asymmetry measurements at the Tevatron {bar {ital p}}{ital p} collider significantly constrain the {ital u} and {ital d} quark distributions, and specifically the slope of the {ital d}({ital x})/{ital u}({ital x}) in the {ital x} range 0.007 to 0.27. We present measurements of the lepton charge asymmetry as a function of lepton rapidity, {ital A}({ital y}{sub {ital l}}) at {radical}{ital s}=1.8 TeV for {parallel}{ital y}{sub {ital l}}{parallel}{lt}2.0, for {ital W} decays to electrons and muons recorded by the CDF detector during the 1992{endash}93 run ({approx_equal}20 {ital pb}{sup {minus}1}), and the first {approx_equal}50 {ital pb}{sup {minus}1} of data from the 1994{endash}95 run. These precise data make possible further discrimination between sets of modern parton distributions. In particular it is found that the most recent parton distributions, which included the CDF 1992{endash}93 W asymmetry data in their fits (MRSA, CTEQ3M and GRV94) are still in good agreement with the more precise data from the 1994{endash}95 run. {ital W} charge asymmetry results from DO/ based on {approx_equal}6.5 {ital pb}{sup {minus}1} of data from the 1992{endash}93 run and {approx_equal}29.7 {ital pb}{sup {minus}1} of data from the 1994{endash}1995 run, using the W decays to muons, are also presented and are found to be consistent with CDF results. In addition, we present preliminary measurement of the Drell-Yan cross-section by CDF using a dielectron sample collected during the 1993{endash}94 run ({approx_equal}20 {ital pb}{sup {minus}1}) and a high mass dimuon sample from the combined 1993{endash}94 and 1994{endash}95 runs ({approx_equal}70 {ital pb}{sup {minus}1}). The measurement is in good agreement with predictions using the most recent parton density functions in a dilepton mass range between 11 and 350 GeV/{ital c}{sup 2}. {copyright} {ital 1996 American Institute of Physics.}

  19. Spin Structure Moments of the Proton and Deuteron

    SciTech Connect

    Slifer, Karl; Rondon-Aramayo, Oscar; Aghalaryan, Aram; Ahmidouch, Abdellah; Asaturyan, Razmik; Bloch, Frederic; Boeglin, Werner; Bosted, Peter; Carasco, Cedric; Carlini, Roger; Cha, Jinseok; Chen, Jian-Ping; Christy, Michael; Cole, Leon; Coman, Luminita; Crabb, Donald; Danagoulian, Samuel; Day, Donal; Dunne, James; Elaasar, Mostafa; Ent, Rolf; Fenker, Howard; Frlez, Emil; Gaskell, David; Gan, Liping; Gomez, Javier; Hu, Bitao; Jourdan, Juerg; Jones, Mark; Keith, Christopher; Keppel, Cynthia; Khandaker, Mahbubul; Klein, Andreas; Kramer, Laird; Liang, Yongguang; Lichtenstadt, Jechiel; Lindgren, Richard; Mack, David; McKee, Paul; McNulty, Dustin; Meekins, David; Mkrtchyan, Hamlet; Nasseripour, Rakhsha; Niculescu, Maria-Ioana; Normand, Kristoff; Norum, Blaine; Pocanic, Dinko; Prok, Yelena; Raue, Brian; Reinhold, Joerg; Roche, Julie; Rohe, Daniela; Savvinov, Nikolai; Sawatzky, Bradley; Seely, Mikell; Sick, Ingo; Smith, C.; Smith, G.; Stepanyan, Samuel; Tang, Liguang; Tajima, Shigeyuki; Testa, Giuseppe; Vulcan, William; Wang, Kebin; Warren, G.; Wesselmann, Frank; Wood, Stephen; Yan, Chen; Yuan, Lulin; Yun, Junho; Zeier, Markus; Guo Zhu, Hong

    2009-01-01

    Moments of the spin structure functions g1 and g2 of the proton and deuteron have been measured in the resonance region at intermediate four momentum transfer. We perform a Nachtmann moment analysis of this data, along with isovector and isoscalar combinations, in order to rigorously account for target mass effects. This analysis provides the first definitive evidence for dynamic higher twists.

  20. Simulating the function of sodium/proton antiporters

    PubMed Central

    Alhadeff, Raphael; Warshel, Arieh

    2015-01-01

    The molecular basis of the function of transporters is a problem of significant importance, and the emerging structural information has not yet been converted to a full understanding of the corresponding function. This work explores the molecular origin of the function of the bacterial Na+/H+ antiporter NhaA by evaluating the energetics of the Na+ and H+ movement and then using the resulting landscape in Monte Carlo simulations that examine two transport models and explore which model can reproduce the relevant experimental results. The simulations reproduce the observed transport features by a relatively simple model that relates the protein structure to its transporting function. Focusing on the two key aspartic acid residues of NhaA, D163 and D164, shows that the fully charged state acts as an Na+ trap and that the fully protonated one poses an energetic barrier that blocks the transport of Na+. By alternating between the former and latter states, mediated by the partially protonated protein, protons, and Na+ can be exchanged across the membrane at 2:1 stoichiometry. Our study provides a numerical validation of the need of large conformational changes for effective transport. Furthermore, we also yield a reasonable explanation for the observation that some mammalian transporters have 1:1 stoichiometry. The present coarse-grained model can provide a general way for exploring the function of transporters on a molecular level. PMID:26392528

  1. Structural determinants of proton blockage in aquaporins.

    PubMed

    Chakrabarti, Nilmadhab; Roux, Benoît; Pomès, Régis

    2004-10-15

    Aquaporins are an important class of membrane channels selective for water and linear polyols but impermeable to ions, including protons. Recent computational studies have revealed that the relay of protons through the water-conduction pathway of aquaporin channels is opposed by a substantial free energy barrier peaking at the signature NPA motifs. Here, free-energy simulations and continuum electrostatic calculations are combined to examine the nature and the magnitude of the contribution of specific structural elements to proton blockage in the bacterial glycerol uptake facilitator, GlpF. Potential of mean-force profiles for both hop and turn steps of structural diffusion in the narrow pore are obtained for artificial variants of the GlpF channel in which coulombic interactions between the pore contents and conserved residues Asn68 and Asn203 at the NPA signature motifs, Arg206 at the selectivity filter, and the peptidic backbone of the two half-helices M3 and M7, which are arranged in head-to-head fashion around the NPA motifs, are turned off selectively. A comparison of these results with electrostatic energy profiles for the translocation of a probe cation throughout the water permeation pathway indicates that the free-energy profile for proton movement inside the narrow pore is dominated by static effects arising from the distribution of charged and polar groups of the channel, whereas dielectric effects contribute primarily to opposing the access of H+ to the pore mouths (desolvation penalty). The single most effective way to abolish the free-energy gradients opposing the movement of H+ around the NPA motif is to turn off the dipole moments of helices M3 and M7. Mutation of either of the two NPA Asn residues to Asp compensates for charge-dipole and dipole-dipole effects opposing the hop and turn steps of structural diffusion, respectively, and dramatically reduces the free energy barrier of proton translocation, suggesting that these single mutants could

  2. Structure in the Proton and the Neutron

    DOE R&D Accomplishments Database

    Hofstadter, R.

    1958-06-01

    A survey of the recent work on the structures of the proton and the neutron carried out by high-energy electron-scattering methods is presented. Early work established finite size effects in the proton and led to information about the charge and magnetic density distributions in the proton. The rms size was established to be close to (0.77 plus or minus 0.10) x 10{sup -13} cm, and the density distributions of charge and anomalous magnetic moment were shown to be approximately of the same shape. The form factors could be described in terms of several alternative models given, for example, by an exponential, gaussian, hollow exponential, hollow gaussian, etc., distribution of densities. Many other shapes were excluded by the experimental data. Recent work by Bumiller and Hofstadter now fixes one among these models that is appropriate to the proton and provides an extremely good fit at all angles between energies of 200 and 650 Mev. The new evidence clearly favors the exponential model with rms radius (0.80 plus or minus 0.04) 10{sup -13} cm. Recent studies of the proton have attempted to answer the question: how closely similar are the charge and magnetic form factors? This work now shows that the distributions have the same sizes and shapes to within 10 per cent, and each distribution is given very closely by the exponential model described above with radius (0.80 plus or minus 0.04) x 10{sup -13}. Certain other similar models will be discussed. Early work on the inelastic continuum in the deuteron established that the neutron's magnetic structure was extended and not a point. It was further shown that the neutron's size was approximately the same as that of the proton. This work has recently been extended by Yearian and Hofstadter to a determination of the variation of the neutron's magnetic form factor over the range where the proton's form factor is known. The new results show: (1) the neutron is not a point, (2) the neutron's magnetic structure has a size lying

  3. Internal spin structure of the proton from high energy polarized e-p scattering

    SciTech Connect

    Hughes, V.W.; Baum, G.; Bergstroem, M.R.

    1981-02-01

    A review is given of experimental knowledge of the spin dependent structure functions of the proton, which is based on inclusive high energy scattering of longitudinal polarized electrons by longitudinally polarized protons in both the deep inelastic and resonance regions, and includes preliminary results from our most recent SLAC experiment. Implications for scaling, sum rules, models of proton structure, and the hyperfine structure interval in hydrogen are given. Possible future directions of research are indicated.

  4. Ring-shaped velocity distribution functions in energy-dispersed structures formed at the boundaries of a proton stream injected into a transverse magnetic field: Test-kinetic results

    NASA Astrophysics Data System (ADS)

    Voitcu, Gabriel; Echim, Marius M.

    2012-02-01

    In this paper, we discuss the formation of ring-shaped and gyro-phase restricted velocity distribution functions (VDFs) at the edges of a cloud of protons injected into non-uniform distributions of the electromagnetic field. The velocity distribution function is reconstructed using the forward test-kinetic method. We consider two profiles of the electric field: (1) a non-uniform E-field obtained by solving the Laplace equation consistent with the conservation of the electric drift and (2) a constant and uniform E-field. In both cases, the magnetic field is similar to the solutions obtained for tangential discontinuities. The initial velocity distribution function is Liouville mapped along numerically integrated trajectories. The numerical results show the formation of an energy-dispersed structure due to the energy-dependent displacement of protons towards the edges of the cloud by the gradient-B drift. Another direct effect of the gradient-B drift is the formation of ring-shaped velocity distribution functions within the velocity-dispersed structure. Higher energy particles populate the edges of the proton beam, while smaller energies are located in the core. Non-gyrotropic velocity distribution functions form on the front-side and trailing edge of the cloud; this effect is due to remote sensing of energetic particles with guiding centers inside the beam. The kinetic features revealed by the test-kinetic solutions have features similar to in-situ velocity distribution functions observed by Cluster satellites in the magnetotail, close to the neutral sheet.

  5. Structural Proton Diffusion along Lipid Bilayers

    PubMed Central

    Serowy, Steffen; Saparov, Sapar M.; Antonenko, Yuri N.; Kozlovsky, Wladas; Hagen, Volker; Pohl, Peter

    2003-01-01

    For H+ transport between protein pumps, lateral diffusion along membrane surfaces represents the most efficient pathway. Along lipid bilayers, we measured a diffusion coefficient of 5.8 × 10−5 cm2 s−1. It is too large to be accounted for by vehicle diffusion, considering proton transport by acid carriers. Such a speed of migration is accomplished only by the Grotthuss mechanism involving the chemical exchange of hydrogen nuclei between hydrogen-bonded water molecules on the membrane surface, and the subsequent reorganization of the hydrogen-bonded network. Reconstitution of H+-binding sites on the membrane surface decreased the velocity of H+ diffusion. In the absence of immobile buffers, structural (Grotthuss) diffusion occurred over a distance of 100 μm as shown by microelectrode aided measurements of the spatial proton distribution in the immediate membrane vicinity and spatially resolved fluorescence measurements of interfacial pH. The efficiency of the anomalously fast lateral diffusion decreased gradually with an increase in mobile buffer concentration suggesting that structural diffusion is physiologically important for distances of ∼10 nm. PMID:12547784

  6. Protonated hydrochlorous acid (HOClH + ): Molecular structure, vibrational frequencies, and proton affinity

    NASA Astrophysics Data System (ADS)

    Francisco, J. S.; Sander, S. P.

    1995-06-01

    Protonated hydrochlorous acid (HOClH+) has been examined theoretically. Equilibrium geometries have been optimized and harmonic vibrational frequencies obtained for each of the parent and protonated structures at various levels of theory employing second-order Møller-Plesset perturbation interaction theory (MP2), singles and doubles excitation configuration interaction theory (CISD), and coupled-cluster theory (CCSD). Our study has found that protonation of the oxygen of HOCl is favored over protonation at the chlorine site. Protonation of the oxygen leads to a pyramidal structure of Cs symmetry. There is a planar Cs structure which is the inversion transition state. The inversion barrier is 3.2 kcal mol-1. The proton affinity of hypochlorous acid, HOCl, is found to be 153.1 kcal mol-1 at 0 K.

  7. Measurements of the u valence quark distribution function in the proton and u quark fragmentation functions

    NASA Astrophysics Data System (ADS)

    Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I. G.; Blum, D.; Böhm, E.; De Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S. C.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffre, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, A.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Poensgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Scholz, M.; Schouten, M.; Schröder, T.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thenard, J. M.; Thompson, J. C.; De la Torre, A.; Toth, J.; Urban, L.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.; European Muon Collaboration

    1989-07-01

    A new determination of the u valence quark distribution function in the proton is obtained from the analysis of identified charged pions, kaons, protons and antiprotons produced in muon-proton and muon-deuteron scattering. The comparison with results obtained in inclusive deep inelastic lepton-nucleon scattering provides a further test of the quark-parton model. The u quark fragmentation functions into positive and negative pions, kaons, protons and antiprotons are also measured.

  8. A broken-symmetry density functional study of structures, energies, and protonation states along the catalytic O-O bond cleavage pathway in ba3 cytochrome c oxidase from Thermus thermophilus.

    PubMed

    Han Du, Wen-Ge; Götz, Andreas W; Yang, Longhua; Walker, Ross C; Noodleman, Louis

    2016-08-21

    Broken-symmetry density functional calculations have been performed on the [Fea3, CuB] dinuclear center (DNC) of ba3 cytochrome c oxidase from Thermus thermophilus in the states of [Fea3(3+)-(HO2)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], using both PW91-D3 and OLYP-D3 functionals. Tyr237 is a special tyrosine cross-linked to His233, a ligand of CuB. The calculations have shown that the DNC in these states strongly favors the protonation of His376, which is above propionate-A, but not of the carboxylate group of propionate-A. The energies of the structures obtained by constrained geometry optimizations along the O-O bond cleavage pathway between [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] have also been calculated. The transition of [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] → [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] shows a very small barrier, which is less than 3.0/2.0 kcal mol(-1) in PW91-D3/OLYP-D3 calculations. The protonation state of His376 does not affect this O-O cleavage barrier. The rate limiting step of the transition from state A (in which O2 binds to Fea3(2+)) to state PM ([Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], where the O-O bond is cleaved) in the catalytic cycle is, therefore, the proton transfer originating from Tyr237 to O-O to form the hydroperoxo [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] state. The importance of His376 in proton uptake and the function of propionate-A/neutral-Asp372 as a gate to prevent the proton from back-flowing to the DNC are also shown. PMID:27094074

  9. Proton NMR studies of functionalized nanoparticles in aqueous environments

    NASA Astrophysics Data System (ADS)

    Tataurova, Yulia Nikolaevna

    in high-resolution NMR spectra. This technique is selective for protons on the surface organic functional groups due to their motional averaging in solution. In this study, 1H solution NMR spectroscopy was used to investigate the interface of the organic functional groups in D2O. The pKa for these functional groups covalently bound to the surface of nanoparticles was determined using an NMR-pH titration method based on the variation in the proton chemical shift for the alkyl group protons closest to the amine group with pH. The adsorption of toxic contaminants (chromate and arsenate anions) on the surface of functionalized silicalite-1 and mesoporous silica nanoparticles has been studied by 1H solution NMR spectroscopy. With this method, the surface bound contaminants are detected. The analysis of the intensity and position of these peaks allows quantitative assessment of the relative amounts of functional groups with adsorbed metal ions. These results demonstrate the sensitivity of solution NMR spectroscopy to the electronic environment and structure of the surface functional groups on porous nanomaterials.

  10. Proton assisted recoupling and protein structure determination

    PubMed Central

    De Paëpe, Gaël; Lewandowski, Józef R.; Loquet, Antoine; Böckmann, Anja; Griffin, Robert G.

    2008-01-01

    We introduce a homonuclear version of third spin assisted recoupling, a second-order mechanism that can be used for polarization transfer between 13C or 15N spins in magic angle spinning (MAS) NMR experiments, particularly at high spinning frequencies employed in contemporary high field MAS experiments. The resulting sequence, which we refer to as proton assisted recoupling (PAR), relies on a cross-term between 1H–13C (or 1H–15N) couplings to mediate zero quantum 13C–13C (or 15N–15N recoupling). In particular, using average Hamiltonian theory we derive an effective Hamiltonian for PAR and show that the transfer is mediated by trilinear terms of the form C1±C2∓HZ for 13C–13C recoupling experiments (or N1±N2∓HZ for 15N–15N). We use analytical and numerical simulations to explain the structure of the PAR optimization maps and to delineate the PAR matching conditions. We also detail the PAR polarization transfer dependence with respect to the local molecular geometry and explain the observed reduction in dipolar truncation. Finally, we demonstrate the utility of PAR in structural studies of proteins with 13C–13C spectra of uniformly 13C, 15N labeled microcrystalline Crh, a 85 amino acid model protein that forms a domain swapped dimer (MW=2×10.4 kDa). The spectra, which were acquired at high MAS frequencies (ωr2π>20 kHz) and magnetic fields (750–900 MHz 1H frequencies) using moderate rf fields, exhibit numerous cross peaks corresponding to long (up to 6–7 Å) 13C–13C distances which are particularly useful in protein structure determination. Using results from PAR spectra we calculate the structure of the Crh protein. PMID:19123534

  11. Proton assisted recoupling and protein structure determination

    NASA Astrophysics Data System (ADS)

    de Paëpe, Gaël; Lewandowski, Józef R.; Loquet, Antoine; Böckmann, Anja; Griffin, Robert G.

    2008-12-01

    We introduce a homonuclear version of third spin assisted recoupling, a second-order mechanism that can be used for polarization transfer between 13C or 15N spins in magic angle spinning (MAS) NMR experiments, particularly at high spinning frequencies employed in contemporary high field MAS experiments. The resulting sequence, which we refer to as proton assisted recoupling (PAR), relies on a cross-term between 1H-13C (or 1H-15N) couplings to mediate zero quantum 13C-13C (or 15N-15N recoupling). In particular, using average Hamiltonian theory we derive an effective Hamiltonian for PAR and show that the transfer is mediated by trilinear terms of the form C1+/-C2-/+HZ for 13C-13C recoupling experiments (or N1+/-N2-/+HZ for 15N-15N). We use analytical and numerical simulations to explain the structure of the PAR optimization maps and to delineate the PAR matching conditions. We also detail the PAR polarization transfer dependence with respect to the local molecular geometry and explain the observed reduction in dipolar truncation. Finally, we demonstrate the utility of PAR in structural studies of proteins with 13C-13C spectra of uniformly 13C, 15N labeled microcrystalline Crh, a 85 amino acid model protein that forms a domain swapped dimer (MW=2×10.4 kDa). The spectra, which were acquired at high MAS frequencies (ωr2π>20 kHz) and magnetic fields (750-900 MHz 1H frequencies) using moderate rf fields, exhibit numerous cross peaks corresponding to long (up to 6-7 A˚) 13C-13C distances which are particularly useful in protein structure determination. Using results from PAR spectra we calculate the structure of the Crh protein.

  12. Spin Structure Function Measurements in Hall C at Jefferson Lab

    SciTech Connect

    Wood, Stephen A.

    2008-11-01

    This presentation introduces the spin structure functions and resonant spin structure, and it discusses the experimental approaches for studying spin structure via polarized electron beam interactions with frozen polarized proton and deuteron targets.

  13. Measurement of single spin asymmetry and fifth structure function for the proton(electron vec, electron Kaon+)Lambda reaction with CEBAF Large Acceptance Spectrometer (CLAS)

    SciTech Connect

    Rahksha Nasseripour

    2005-08-31

    The single spin asymmetry, A{sub LT} ?, and the polarized structure function, ?{sub LT}?, for the p(e,e?K{sup +})? reaction in the resonance region have been measured and extracted using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Data were taken at an electron beam energy of 2.567 GeV. The large acceptance of CLAS allows for full azimuthal angle coverage over a large range of center-of-mass scattering angles. Results were obtained that span a range in Q{sup 2} from 0.5 to 1.3 GeV{sup 2} and W from threshold up to 2.1 GeV and were compared to existing theoretical calculations. The polarized structure function is sensitive to the interferences between various resonant amplitudes, as well as to resonant and non-resonant amplitudes. This measurement is essential for understanding the structure of nucleons and searching for previously undetected nucleon excited states (resonances) predicted by quark models. The W dependence of the ?{sub LT} ? in the kinematic regions dominated by s and u channel exchange (cos q{sup cm} k = ?0.50, ?0.167, 0.167) indicated possible resonance structures not predicted by theoretical calculations. The ?{sub LT} ? behavior around W = 1.875 GeV could be the signature of a resonance predicted by the quark models and possibly seen in photoproduction. In the very forward angles where the reaction is dominated by the t-channel, the average ?{sub LT} ? was zero. There was no indication of the interference between resonances or resonant and non-resonant amplitudes. This might be indicating the dominance of a single t-channel exchange. Study of the sensitivity of the fifth structure function data to the resonance around 1900 MeV showed that these data were highly sensitive to the various assumptions of the models for the quantum number of this resonance. This project was part of a larger CLAS program to measure cross sections and polarization observables for kaon electroproduction in the nucleon resonance region.

  14. Proton Spin Structure from Large Momentum Effective Theory

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Hui; Ji, Xiangdong; Zhao, Yong

    2016-08-01

    Recently a large momentum effective theory approach has been proposed to compute parton observables. We discuss its application to the spin structure of the proton. In particular, we explain how the partonic contribution to the proton spin in the Jaffe-Manohar sum rule can be computed within the large momentum effective theory framework.

  15. Structure and conformation of protonated D-(+)-biotin in the unsolvated state.

    PubMed

    Fraschetti, Caterina; Filippi, Antonello; Guarcini, Laura; Steinmetz, Vincent; Speranza, Maurizio

    2015-05-21

    A combined computational and infrared multiphoton dissociation (IRMPD) spectroscopic investigation shows that protonated d-(+)-biotin, formed in the gas phase by ESI-MS, acquires a folded structure with proton bonding between the ureido and valeryl carbonyls, and that only a single conformer of such a structure predominates. A uniform frequency vs distance correlation function is proposed for the O(+)-H···O and N-H···O bonds involved in the folded conformers of O2'-protonated d-(+)-biotin in the gas phase which, therefore, depends exclusively on the corresponding geometric parameters. PMID:25938640

  16. Spin structure of the proton from polarized inclusive deep-inelastic muon-proton scattering

    SciTech Connect

    Spin Muon Collaboration

    1997-11-01

    We have measured the spin-dependent structure function g{sub 1}{sup p} in inclusive deep-inelastic scattering of polarized muons off polarized protons, in the kinematic range 0.003{lt}x{lt}0.7 and 1GeV{sup 2}{lt}Q{sup 2}{lt}60GeV{sup 2}. A next-to-leading order QCD analysis is used to evolve the measured g{sub 1}{sup p}(x,Q{sup 2}) to a fixed Q{sub 0}{sup 2}. The first moment of g{sub 1}{sup p} at Q{sub 0}{sup 2}=10GeV{sup 2} is {Gamma}{sub 1}{sup p}=0.136{plus_minus}0.013 (stat) {plus_minus}0.009 (syst) {plus_minus}0.005 (evol). This result is below the prediction of the Ellis-Jaffe sum rule by more than two standard deviations. The singlet axial charge a{sub 0} is found to be 0.28{plus_minus}0.16. In the Adler-Bardeen factorization scheme, {Delta}g{approx_equal}2 is required to bring {Delta}{Sigma} in agreement with the quark-parton model. A combined analysis of all available proton, deuteron, and {sup 3}He data confirms the Bjorken sum rule. {copyright} {ital 1997} {ital The American Physical Society}

  17. Exchangers man the pumps: Functional interplay between proton pumps and proton-coupled Ca(2+) exchangers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tonoplast-localised proton-coupled Ca(2+) transporters encoded by cation/H(+) exchanger (CAX) genes play a critical role in sequestering Ca(2+) into the vacuole. These transporters may function in coordination with Ca(2+) release channels, to shape stimulus-induced cytosolic Ca(2+) elevations. Recen...

  18. Structural basis for proton conduction and inhibition by the influenza M2 protein

    PubMed Central

    Hong, Mei; DeGrado, William F

    2012-01-01

    The influenza M2 protein forms an acid-activated and drug-sensitive proton channel in the virus envelope that is important for the virus lifecycle. The functional properties and high-resolution structures of this proton channel have been extensively studied to understand the mechanisms of proton conduction and drug inhibition. We review biochemical and electrophysiological studies of M2 and discuss how high-resolution structures have transformed our understanding of this proton channel. Comparison of structures obtained in different membrane-mimetic solvents and under different pH using X-ray crystallography, solution NMR, and solid-state NMR spectroscopy revealed how the M2 structure depends on the environment and showed that the pharmacologically relevant drug-binding site lies in the transmembrane (TM) pore. Competing models of proton conduction have been evaluated using biochemical experiments, high-resolution structural methods, and computational modeling. These results are converging to a model in which a histidine residue in the TM domain mediates proton relay with water, aided by microsecond conformational dynamics of the imidazole ring. These mechanistic insights are guiding the design of new inhibitors that target drug-resistant M2 variants and may be relevant for other proton channels. PMID:23001990

  19. A Proton-cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Viñas, A.; Jian, L. K.; Roberts, D. A.; O'Modhrain, S.; Gilbert, J. A.; Zurbuchen, T. H.

    2016-03-01

    We use audification of 0.092 s cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes \\gt 0.1 nT near the ion gyrofrequency (˜0.1 Hz) with duration longer than 1 hr during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.

  20. A Proton-Cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Vinas, A.; Jian, L. K.; Roberts, D. A.; O’Modhrain, S.; Gilbert, J. A.; Zurbuchen, T. H.

    2016-01-01

    We use audification of 0.092 seconds cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes greater than 0.1 nanoteslas near the ion gyrofrequency (approximately 0.1 hertz) with duration longer than 1 hour during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.

  1. Structure of fully protonated proteins by proton-detected magic-angle spinning NMR.

    PubMed

    Andreas, Loren B; Jaudzems, Kristaps; Stanek, Jan; Lalli, Daniela; Bertarello, Andrea; Le Marchand, Tanguy; Cala-De Paepe, Diane; Kotelovica, Svetlana; Akopjana, Inara; Knott, Benno; Wegner, Sebastian; Engelke, Frank; Lesage, Anne; Emsley, Lyndon; Tars, Kaspars; Herrmann, Torsten; Pintacuda, Guido

    2016-08-16

    Protein structure determination by proton-detected magic-angle spinning (MAS) NMR has focused on highly deuterated samples, in which only a small number of protons are introduced and observation of signals from side chains is extremely limited. Here, we show in two fully protonated proteins that, at 100-kHz MAS and above, spectral resolution is high enough to detect resolved correlations from amide and side-chain protons of all residue types, and to reliably measure a dense network of (1)H-(1)H proximities that define a protein structure. The high data quality allowed the correct identification of internuclear distance restraints encoded in 3D spectra with automated data analysis, resulting in accurate, unbiased, and fast structure determination. Additionally, we find that narrower proton resonance lines, longer coherence lifetimes, and improved magnetization transfer offset the reduced sample size at 100-kHz spinning and above. Less than 2 weeks of experiment time and a single 0.5-mg sample was sufficient for the acquisition of all data necessary for backbone and side-chain resonance assignment and unsupervised structure determination. We expect the technique to pave the way for atomic-resolution structure analysis applicable to a wide range of proteins. PMID:27489348

  2. Nanoparticles of mesoporous SO3H-functionalized Si-MCM-41 with superior proton conductivity.

    PubMed

    Marschall, Roland; Bannat, Inga; Feldhoff, Armin; Wang, Lianzhou; Lu, Gao Qing Max; Wark, Michael

    2009-04-01

    Nanometer-sized mesoporous silica particles of around 100-nm diameter functionalized with a large amount of sulfonic acid groups are prepared using a simple and fast in situ co-condensation procedure. A highly ordered hexagonal pore structure is established by applying a pre-hydrolysis step in a high-dilution synthesis approach, followed by adding the functionalization agent to the reaction mixture. The high-dilution approach is advantageous for the in situ functionalization since no secondary reagents for an effective particle and framework formation are needed. Structural data are determined via electron microscopy, nitrogen adsorption, and X-ray diffraction, proton conductivity values of the functionalized samples are measured via impedance spectroscopy. The obtained mesoporous SO(3)H-MCM-41 nanoparticles demonstrate superior proton conductivity than their equally loaded micrometer-sized counterparts, up to 5 x 10(-2) S cm(-1). The mesoporosity of the particles turns out to be very important for effective proton transport since non-porous silica nanoparticles exhibit worse efficient proton transport, and the obtained particle size dependence might open up a new route in rational design of highly proton conductive materials. PMID:19226596

  3. Inverse structure functions

    SciTech Connect

    Pearson, Bruce R.; Water, Willem van de

    2005-03-01

    While the ordinary structure function in turbulence is concerned with the statistical moments of the velocity increment {delta}u measured over a distance r, the inverse structure function is related to the distance r where the turbulent velocity exits the interval {delta}u. We study inverse structure functions of wind-tunnel turbulence which covers a range of Reynolds numbers Re{sub {lambda}}=400-1100. We test a recently proposed relation between the scaling exponents of the ordinary structure functions and those of the inverse structure functions [S. Roux and M. H. Jensen, Phys. Rev. E 69, 16309 (2004)]. The relatively large range of Reynolds numbers in our experiment also enables us to address the scaling with Reynolds number that is expected to highlight the intermediate dissipative range. While we firmly establish the (relative) scaling of inverse structure functions, our experimental results fail both predictions. Therefore, the question of the significance of inverse structure functions remains open.

  4. Measurements of the Q{sup 2}-Dependence of the Proton and Neutron Spin Structure Functions g{sub 1}{sup p} and g{sub 1}{sup n}

    SciTech Connect

    Perry Anthony; R.G. Arnold; Todd Averett; H.R. Band; M.C. Berisso; H. Borel; Peter Bosted; Stephen Bueltmann; M. Buenerd; T. Chupp; Steve Churchwell; G.R. Court; Donald Crabb; Donal Day; Piotr Decowski; P. DePietro; Robin D. Erbacher; R. Erickson; A. Feltham; Helene Fonvieille; Emil Frlez; R. Gearhart; V. Ghazikhanian; Javier Gomez; Keith Griffioen; C. Harris; M.A. Houlden; Emlyn Hughes; Charles Hyde-wright; G. Igo; Sebastien Incerti; John Jensen; J.R. Johnson; Paul King; Yu.G. Kolomensky; Sebastian Kuhn; Richard Lindgren; R.M. Lombard-Nelsen; Jacques Marroncle; James Mccarthy; Paul Mckee; Werner Meyer; Gregory Mitchell; Joseph Mitchell; Michael Olson; Seppo Penttila; Gerald Peterson; Gerassimos Petratos; R. Pitthan; Dinko Pocanic; R. Prepost; C. Prescott; Liming Qin; Brian Raue; D. Reyna; L.S. Rochester; Stephen Rock; Oscar Rondon-aramayo; Franck Sabatie; Ingo Sick; Tim Smith; Lee Sorrell; F. Staley; S. St. Lorant; L.M. Stuart; Z. Szalata; Y. Terrien; William Tobias; Luminita Todor; T. Toole; S. Trentalange; D. Walz; Robert Welsh; Frank Wesselmann; T.R. Wright; C.C. Young; Markus Zeier; Hong Guo Zhu; Benedikt Zihlmann

    2000-11-09

    The structure functions g{sub 1}{sup p} and g{sub 1}{sup n} have been measured over the range 0.014 < x < 0.9 and 1 < Q{sup 2} < 40 GeV{sup 2} using deep-inelastic scattering of 48 GeV longitudinally polarized electrons from polarized protons and deuterons. We find that the Q{sup 2} dependence of g{sub 1}{sup p} (g{sub 1}{sup n}) at fixed x is very similar to that of the spin-averaged structure function F{sub 1}{sup p} (F{sub 1}{sup n}). From a NLO QCD fit to all available data we find {Gamma}{sub 1}{sup p} - {Gamma}{sub 1}{sup n} = 0.176 {+-} 0.003 {+-} 0.007 at Q{sup 2} = 5 GeV{sup 2}, in agreement with the Bjorken sum rule prediction of 0.182 {+-} 0.005.

  5. Jet fragmentation functions in proton-proton collisions using soft-collinear effective theory

    NASA Astrophysics Data System (ADS)

    Chien, Yang-Ting; Kang, Zhong-Bo; Ringer, Felix; Vitev, Ivan; Xing, Hongxi

    2016-05-01

    The jet fragmentation function describes the longitudinal momentum distribution of hadrons inside a reconstructed jet. We study the jet fragmentation function in proton-proton collisions in the framework of soft-collinear effective theory (SCET). We find that, up to power corrections, the jet fragmentation function can be expressed as the ratio of the fragmenting jet function and the unmeasured jet function. Using renormalization group techniques, we are able to resum large logarithms of jet radii R in the perturbative expansion of the cross section. We use our theoretical formalism to describe the jet fragmentation functions for light hadron and heavy meson production measured at the Large Hadron Collider (LHC). Our calculations agree very well with the experimental data for the light hadron production. On the other hand, although our calculations for the heavy meson production inside jets are consistent with the PYTHIA simulation, they fail to describe the LHC data. We find that the jet fragmentation function for heavy meson production is very sensitive to the gluon-to-heavy-meson fragmentation function.

  6. Structures of protonated methanol clusters and temperature effects.

    PubMed

    Fifen, Jean Jules; Nsangou, Mama; Dhaouadi, Zoubeida; Motapon, Ousmanou; Jaidane, Nejm-Eddine

    2013-05-14

    The accurate evaluation of pKa's, or solvation energies of the proton in methanol at a given temperature is subject to the determination of the most favored structures of various isomers of protonated (H(+)(MeOH)n) and neutral ((MeOH)n) methanol clusters in the gas phase and in methanol at that temperature. Solvation energies of the proton in a given medium, at a given temperature may help in the determination of proton affinities and proton dissociation energies related to the deprotonation process in that medium and at that temperature. pKa's are related to numerous properties of drugs. In this work, we were interested in the determination of the most favored structures of various isomers of protonated methanol clusters in the gas phase and in methanol, at a given temperature. For this aim, the M062X/6-31++G(d,p) and B3LYP/6-31++G(d,p) levels of theory were used to perform geometries optimizations and frequency calculations on various isomers of (H(+)(MeOH)n) in both phases. Thermal effects were retrieved using our homemade FORTRAN code. Thus, we accessed the relative populations of various isomers of protonated methanol clusters, in both phases for temperatures ranging from 0 to 400 K. As results, in the gas phase, linear structures are entropically more favorable at high temperatures, while more compact ones are energetically more favorable at lower temperatures. The trend is somewhat different when bulk effects are taken into account. At high temperatures, the linear structure only dominates the population for n ≤ 6, while it is dominated by the cyclic structure for larger cluster sizes. At lower temperatures, compact structures still dominate the population, but with an order different from the one established in the gas phase. Hence, temperature effects dominate solvent effects in small cluster sizes (n ≤ 6), while the reverse trend is noted for larger cluster sizes. PMID:23676038

  7. Structure functions for light nuclei

    SciTech Connect

    S.A. Kulagin, R. Petti

    2010-11-01

    We discuss the nuclear EMC effect with particular emphasis on recent data for light nuclei including 2H, 3He, 4He, 9Be, 12C and 14N. In order to verify the consistency of available data, we calculate the \\chi^2 deviation between different data sets. We find a good agreement between the results from the NMC, SLAC E139, and HERMES experiments. However, our analysis indicates an overall normalization offset of about 2% in the data from the recent JLab E03-103 experiment with respect to previous data for nuclei heavier than 3He. We also discuss the extraction of the neutron/proton structure function ratio F2n/F2p from the nuclear ratios 3He/2H and 2H/1H. Our analysis shows that the E03-103 data on 3He/2H require a renormalization of about 3% in order to be consistent with the F2n/F2p ratio obtained from the NMC experiment. After such a renormalization, the 3He data from the E03-103 data and HERMES experiments are in a good agreement. Finally, we present a detailed comparison between data and model calculations, which include a description of the nuclear binding, Fermi motion and off-shell corrections to the structure functions of bound proton and neutron, as well as the nuclear pion and shadowing corrections. Overall, a good agreement with the available data for all nuclei is obtained.

  8. ``PROTON Sponges": a Rigid Organic Scaffold to Reveal the Quantum Structure of the Intramolecular Proton Bond

    NASA Astrophysics Data System (ADS)

    Deblase, Andrew F.; Johnson, Mark A.; Scerba, Michael T.; Bloom, Steven; Lectka, Thomas; Dudding, Travis

    2012-06-01

    Spectroscopic analysis of systems containing charged hydrogen bonds (e.g. the Zundel ion, {H}5{O}2+) in a vibrationally cold regime is useful in decongesting numerous anharmonic features common to room temperature measurements.[Roscioli, J. R.; et. al. Science 2007] This approach has been extended to conjugate acids of the ``Proton Sponge" family of organic compounds, which contain strong intramolecular hydrogen bonds between proton donor (D) and acceptor (A) groups at the 1- and 8-positions. By performing {H}_2/{D}_2 vibrational predissociation spectroscopy on cryogenically cooled ions, we explore how the proximity and spatial orientation of D and A moieties relates to the spectroscopic signature of the shared proton. In the cases studied ({D = Me2N-H+; A = OH, O(C=O)Ph}), we observe strong anharmonic couplings between the shared proton and dark states that persist at these cryogenic temperatures. This leads to intense NH stretching features throughout the nominal CH stretching region (2800-3000 {cm}-1). Isotopic substitution has verified that the oscillator strength of these broad features is driven by NH stretching. Furthermore, the study of A = O(C=O)Ph has provided a spectroscopic snapshot of the shared proton at work as an active catalytic moiety fostering ester hydrolysis by first order acylium fission ({AAC1}). This is apparent by the high frequency carbonyl stretch at 1792 {cm}-1, which is a consequence of the strong hydrogen bond to the ether-ester oxygen atom. Thus, these ``Proton Sponges" are useful model systems that unearth the quantum structure and reactivity of shared proton interactions in organic compounds.

  9. Insight into proton transfer in phosphotungstic acid functionalized mesoporous silica-based proton exchange membrane fuel cells.

    PubMed

    Zhou, Yuhua; Yang, Jing; Su, Haibin; Zeng, Jie; Jiang, San Ping; Goddard, William A

    2014-04-01

    We have developed for fuel cells a novel proton exchange membrane (PEM) using inorganic phosphotungstic acid (HPW) as proton carrier and mesoporous silica as matrix (HPW-meso-silica) . The proton conductivity measured by electrochemical impedance spectroscopy is 0.11 S cm(-1) at 90 °C and 100% relative humidity (RH) with a low activation energy of ∼14 kJ mol(-1). In order to determine the energetics associated with proton migration within the HPW-meso-silica PEM and to determine the mechanism of proton hopping, we report density functional theory (DFT) calculations using the generalized gradient approximation (GGA). These DFT calculations revealed that the proton transfer process involves both intramolecular and intermolecular proton transfer pathways. When the adjacent HPWs are close (less than 17.0 Å apart), the calculated activation energy for intramolecular proton transfer within a HPW molecule is higher (29.1-18.8 kJ/mol) than the barrier for intermolecular proton transfer along the hydrogen bond. We find that the overall barrier for proton movement within the HPW-meso-silica membranes is determined by the intramolecular proton transfer pathway, which explains why the proton conductivity remains unchanged when the weight percentage of HPW on meso-silica is above 67 wt %. In contrast, the activation energy of proton transfer on a clean SiO2 (111) surface is computed to be as high as ∼40 kJ mol(-1), confirming the very low proton conductivity on clean silica surfaces observed experimentally. PMID:24628538

  10. Molecular structures and protonation state of 2-Mercaptopyridine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Eckert, S.; Miedema, P. S.; Quevedo, W.; O'Cinneide, B.; Fondell, M.; Beye, M.; Pietzsch, A.; Ross, M.; Khalil, M.; Föhlisch, A.

    2016-03-01

    The speciation of 2-Mercaptopyridine in aqueous solution has been investigated with nitrogen 1s Near Edge X-ray Absorption Fine Structure spectroscopy and time dependent Density Functional Theory. The prevalence of distinct species as a function of the solvent basicity is established. No indications of dimerization towards high concentrations are found. The determination of different molecular structures of 2-Mercaptopyridine in aqueous solution is put into the context of proton-transfer in keto-enol and thione-thiol tautomerisms.

  11. The QCD Analysis Of The World Data On Structure Functions g{sub 1}{sup p,d,n} For Proton, Deuteron And Neutron

    SciTech Connect

    Savin, I. A.

    2007-06-13

    The fits of all published data on g1, including the new COMPASS measurements of g{sub 1}{sup d}(x,Q{sup 2}), have been performed by using two different QCD evolution formalisms in the next-to-leading-order (NLO) approximation. In both methods we obtain two solutions for fitted parameters of the parton distribution functions (PDFs), one with {delta}G>0 and the other - with {delta}G<0, where {delta}G is the first moment of the polarized gluon distribution in nucleon.

  12. Possibility to Deduce the Emission Time Sequence of Neutrons and Protons from the Neutron-Proton Correlation Function

    SciTech Connect

    Ghetti, R.; Helgesson, J.; Colonna, N.; Jakobsson, B.; Anzalone, A.; Bellini, V.; Carlen, L.; Cavallaro, S.; Celano, L.; De Filippo, E.

    2001-09-03

    Experimental information has been derived from the neutron-proton correlation function in order to deduce the time sequence of neutrons and protons emitted at 45{sup o} in the E/A=45 MeV {sup 58}Ni+{sup 27}Al reaction.

  13. Structure and function of mitochondrial complex I.

    PubMed

    Wirth, Christophe; Brandt, Ulrich; Hunte, Carola; Zickermann, Volker

    2016-07-01

    Proton-pumping NADH:ubiquinone oxidoreductase (complex I) is the largest and most complicated enzyme of the respiratory chain. Fourteen central subunits represent the minimal form of complex I and can be assigned to functional modules for NADH oxidation, ubiquinone reduction, and proton pumping. In addition, the mitochondrial enzyme comprises some 30 accessory subunits surrounding the central subunits that are not directly associated with energy conservation. Complex I is known to release deleterious oxygen radicals (ROS) and its dysfunction has been linked to a number of hereditary and degenerative diseases. We here review recent progress in structure determination, and in understanding the role of accessory subunits and functional analysis of mitochondrial complex I. For the central subunits, structures provide insight into the arrangement of functional modules including the substrate binding sites, redox-centers and putative proton channels and pump sites. Only for two of the accessory subunits, detailed structures are available. Nevertheless, many of them could be localized in the overall structure of complex I, but most of these assignments have to be considered tentative. Strikingly, redox reactions and proton pumping machinery are spatially completely separated and the site of reduction for the hydrophobic substrate ubiquinone is found deeply buried in the hydrophilic domain of the complex. The X-ray structure of complex I from Yarrowia lipolytica provides clues supporting the previously proposed two-state stabilization change mechanism, in which ubiquinone redox chemistry induces conformational states and thereby drives proton pumping. The same structural rearrangements may explain the active/deactive transition of complex I implying an integrated mechanistic model for energy conversion and regulation. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26921811

  14. Ion-molecule reactions for mass spectrometric identification of functional groups in protonated oxygen-containing monofunctional compounds.

    PubMed

    Watkins, Michael A; Price, Jason M; Winger, Brian E; Kenttämaa, Hilkka I

    2004-02-15

    Protonated oxygen-containing monofunctional compounds react with selected methoxyborane reagents by proton transfer followed by nucleophilic substitution of methanol at the boron atom in a Fourier transform ion cyclotron resonance mass spectrometer. The derivatized oxygen functionality can be identified by H/D exchange, collision-activated dissociation, or both. This information on the identity of the functionalities in the analyte, in conjunction with molecular formula information obtained from exact mass measurements on either the protonated or derivatized analyte, facilitates structure elucidation of unknown organic compounds in a mass spectrometer. PMID:14961727

  15. Features of MotA proton channel structure revealed by tryptophan-scanning mutagenesis.

    PubMed Central

    Sharp, L L; Zhou, J; Blair, D F

    1995-01-01

    The MotA protein of Escherichia coli is a component of the flagellar motors that functions in transmembrane proton conduction. Here, we report several features of MotA structure revealed by use of a mutagenesis-based approach. Single tryptophan residues were introduced at many positions within the four hydrophobic segments of MotA, and the effects on function were measured. Function was disrupted according to a periodic pattern that implies that the membrane-spanning segments are alpha-helices and that identifies the lipid-facing parts of each helix. The results support a hypothesis for MotA structure and mechanism in which water molecules form most of the proton-conducting pathway. The success of this approach in studying MotA suggests that it could be useful in structure-function studies of other integral membrane proteins. Images Fig. 1 PMID:7644518

  16. Tests of proton structure functions using leptons at CDF and D0: W charge asymmetry and Drell-Yan production. Version 1.0

    SciTech Connect

    Barbaro, P. de

    1995-06-13

    High statistics W charge asymmetry measurements at the Tevatron {bar p}p collider significantly constrain the u and d quark distributions, and specifically the slope of the d(x)/u(x) in the x range 0.007 to 0.27. The authors present measurements of lepton charge asymmetry as a function of lepton rapidity, A(y{sub l}) at {radical}s = 1.8 TeV for {vert_bar}y{sub l}{vert_bar} < 2.0, for the W decays to electrons and muons recorded by the CDF detector during the 1992-93 run ({approx} 20 pb{sup {minus}1}), and the first {approx} 50 pb{sup {minus}1} of data from the 1994-95 run. These precise data make possible further discrimination between sets of modern parton distributions. In particular it is found that the most recent parton distributions, which included the CDF 1992-93 W asymmetry data in their fits (MRSA, CTEQ3M and GRV94) are still in good agreement with the more precise data from the 1994-95 run. W charge asymmetry results from D0 based on {approx} 6.5 pb{sup {minus}1} data from 1992-1993 run and {approx} 29.7 pb{sup {minus}1} data from 1994-1995 run, using the W decays to muons, are also presented and are found to be consistent with CDF results. In addition, the authors present preliminary measurement of the Drell-Yan cross-section by CDF using a dielectron sample collected during the 1993-94 run ({approx} 20 pb{sup {minus}1}) and a high mass dimuon sample from the combined 1993-94 and 1994-95 runs ({approx} 70 pb{sup {minus}1}). The measurement is in good agreement with predictions using the most recent PDFs in a dilepton mass range between 11 and 350 GeV/c{sup 2}.

  17. Infrared Structural Biology: Detect Functionally Important Structural Motions of Proteins

    NASA Astrophysics Data System (ADS)

    Xie, Aihua

    Proteins are dynamic. Lack of dynamic structures of proteins hampers our understanding of protein functions. Infrared structural biology (IRSB) is an emerging technology. There are several advantages of IRSB for mechanistic studies of proteins: (1) its excellent dynamic range (detecting structural motions from picoseconds to >= seconds); (2) its high structural sensitivity (detect tiny but functionally important structural motions such as proton transfer and changes in hydrogen bonding interaction); (3) its ability to detect different structural motions simultaneously. Successful development of infrared structural biology demands not only new experimental techniques (from infrared technologies to chemical synthesis and cell biology), but also new data processing (how to translate infrared signals into quantitative structural information of proteins). These topics will be discussed as well as examples of how to use IRSB to study structure-function relationship of proteins. This work was supported by NSF DBI1338097 and OCAST HR10-078.

  18. The Neutron Structure Function

    NASA Astrophysics Data System (ADS)

    Holt, Roy

    2013-10-01

    Knowledge of the neutron structure function is important for testing models of the nucleon, for a complete understanding of deep inelastic scattering (DIS) from nuclei, and for high energy experiments. As there exist no free neutron targets, neutron structure functions have been determined from deep inelastic scattering from the deuteron. Unfortunately, the short-range part of the deuteron wave function becomes important in extracting the neutron structure function at very high Bjorken x. New methods have been devised for Jefferson Lab experiments to mitigate this problem. The BONUS experiment involves tagging spectator neutrons in the deuteron, while the MARATHON experiment minimizes nuclear structure effects by a comparison of DIS from 3H and 3He. A summary of the status and future plans will be presented. This work supported by the U. S. Department of Energy, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

  19. Structure function monitor

    SciTech Connect

    McGraw, John T.; Zimmer, Peter C.; Ackermann, Mark R.

    2012-01-24

    Methods and apparatus for a structure function monitor provide for generation of parameters characterizing a refractive medium. In an embodiment, a structure function monitor acquires images of a pupil plane and an image plane and, from these images, retrieves the phase over an aperture, unwraps the retrieved phase, and analyzes the unwrapped retrieved phase. In an embodiment, analysis yields atmospheric parameters measured at spatial scales from zero to the diameter of a telescope used to collect light from a source.

  20. Crystallographic structure of xanthorhodopsin, the light-driven proton pump with a dual chromophore

    PubMed Central

    Luecke, Hartmut; Schobert, Brigitte; Stagno, Jason; Imasheva, Eleonora S.; Wang, Jennifer M.; Balashov, Sergei P.; Lanyi, Janos K.

    2008-01-01

    Homologous to bacteriorhodopsin and even more to proteorhodopsin, xanthorhodopsin is a light-driven proton pump that, in addition to retinal, contains a noncovalently bound carotenoid with a function of a light-harvesting antenna. We determined the structure of this eubacterial membrane protein–carotenoid complex by X-ray diffraction, to 1.9-Å resolution. Although it contains 7 transmembrane helices like bacteriorhodopsin and archaerhodopsin, the structure of xanthorhodopsin is considerably different from the 2 archaeal proteins. The crystallographic model for this rhodopsin introduces structural motifs for proton transfer during the reaction cycle, particularly for proton release, that are dramatically different from those in other retinal-based transmembrane pumps. Further, it contains a histidine–aspartate complex for regulating the pKa of the primary proton acceptor not present in archaeal pumps but apparently conserved in eubacterial pumps. In addition to aiding elucidation of a more general proton transfer mechanism for light-driven energy transducers, the structure defines also the geometry of the carotenoid and the retinal. The close approach of the 2 polyenes at their ring ends explains why the efficiency of the excited-state energy transfer is as high as ≈45%, and the 46° angle between them suggests that the chromophore location is a compromise between optimal capture of light of all polarization angles and excited-state energy transfer. PMID:18922772

  1. Proton-proton intensity interferometry: Space-time structure of the emitting zone in Ni+Ni collisions

    SciTech Connect

    Korolija, M.; Cindro, N.; Shapira, D.

    1995-12-31

    A brief description is given of the Hanbury-Brown-Twiss effect method for determining the space-time structure of the proton-emitting source in a nucleus-nucleus collision. In this context a measurement of exclusive p-p correlations from {sup 58}Ni+{sup 58}Ni at 850 MeV is analyzed. The data served to study the directional dependence of the p-p correlation function and, for the first time, extract separately the source size and the particle-emission time.

  2. Structure functions for light nuclei

    SciTech Connect

    Kulagin, S. A.; Petti, R.

    2010-11-15

    We discuss the nuclear EMC effect with particular emphasis on recent data for light nuclei including {sup 2}H, {sup 3}He, {sup 4}He, {sup 9}Be, {sup 12}C, and {sup 14}N. In order to verify the consistency of available data, we calculate the {chi}{sup 2} deviation between different data sets. We find a good agreement between the results from the NMC, SLAC E139, and HERMES experiments. However, our analysis indicates an overall normalization offset of about 2% in the data from the recent JLab E03-103 experiment with respect to previous data for nuclei heavier than {sup 3}He. We also discuss the extraction of the neutron/proton structure function ratio F{sub 2}{sup n}/F{sub 2}{sup p} from the nuclear ratios {sup 3}He/{sup 2}H and {sup 2}H/{sup 1}H. Our analysis shows that the E03-103 data on {sup 3}He/{sup 2}H require a renormalization of about 3% in order to be consistent with the F{sub 2}{sup n}/F{sub 2}{sup p} ratio obtained from the NMC experiment. After such a renormalization, the {sup 3}He data from the E03-103 and HERMES experiments are in a good agreement. Finally, we present a detailed comparison between data and model calculations, which include a description of the nuclear binding, Fermi motion, and off-shell corrections to the structure functions of bound proton and neutron, as well as the nuclear pion and shadowing corrections. Overall, a good agreement with the available data for all nuclei is obtained.

  3. Anhydrous phosphoric Acid functionalized sintered mesoporous silica nanocomposite proton exchange membranes for fuel cells.

    PubMed

    Zeng, Jie; He, Beibei; Lamb, Krystina; De Marco, Roland; Shen, Pei Kang; Jiang, San Ping

    2013-11-13

    A novel inorganic proton exchange membrane based on phosphoric acid (PA)-functionalized sintered mesoporous silica, PA-meso-silica, has been developed and investigated. After sintering at 650 °C, the meso-silica powder forms a dense membrane with a robust and ordered mesoporous structure, which is critical for retention of PA and water within the porous material. The PA-meso-silica membrane achieved a high proton conductivity of 5 × 10(-3) to 5 × 10(-2) S cm(-1) in a temperature range of 80-220 °C, which is between 1 and 2 orders of magnitudes higher than a typical membrane Nafion 117 or polybenzimidazole (PBI)/PA in the absence of external humidification. Furthermore, the PA-meso-silica membranes exhibited good chemical stability along with high performance at elevated temperatures, producing a peak power density of 632 mW cm(-2) using a H2 fuel at 190 °C in the absence of external humidification. The high membrane proton conductivity and excellent fuel cell performance demonstrate the utility of PA-meso-silica as a new class of inorganic proton exchange membranes for use in the high-temperature proton exchange membrane fuel cells (PEMFCs). PMID:24125494

  4. Proton affinity determinations and proton-bound dimer structure indications in C2 to C15, (alpha),(omega)-alkyldiamines

    NASA Technical Reports Server (NTRS)

    Karpas, Z.; Harden, C. S.; Smith, P. B. W.

    1995-01-01

    The 'kinetic method' was used to determine the proton affinity (PA) of a,coalkyldiamines from collision induced dissociation (CID) studies of protonated heterodimers. These PA values were consistently lower than those reported in the proton affinity scale. The apparent discrepancy was rationalized in terms of differences in the conformation of the protonated diamine monomers. The minimum energy species, formed by equilibrium proton transfer processes, have a cyclic conformation and the ion charge is shared by both amino-groups which are bridged by the proton. On the other hand, the species formed through dissociation of protonated dimers have a linear structure and the charge is localized on one of the amino-groups. Thus, the difference in the PA values obtained by both methods is a measure of the additional stability acquired by the protonated diamines through cyclization and charge delocalization. The major collision dissociation pathway of the protonated diamine monomers involved elimination of an ammonia moiety. Other reactions observed included loss of the second amino-group and several other bond cleavages. CID of the protonated dimers involved primarily formation of a protonated monomer through cleavage of the weaker hydrogen bond and subsequently loss of ammonia at higher collision energies. As observed from the CID studies, doubly charged ions were also formed from the diamines under conditions of the electrospray ionization.

  5. New results on proton structure from HERA

    NASA Astrophysics Data System (ADS)

    Raičević, Nataša

    2016-03-01

    In this paper we show the new set of parton distribution functions (PDFs) determined using new combined H1 and ZEUS data on neutral and charged current inclusive cross sections from all running periods (1994-2007). The combined data are used as the sole input to NLO and NNLO QCD analyses. The new set of PDFs is termed as HERAPDF2.0. Also we show an extended QCD analysis at NLO including the combined data on jet and charm production which enables the simultaneous determination of PDFs (HERAPDF2.0Jets) and the strong coupling constant from HERA data alone.

  6. Outcomes of Proton Therapy for Patients With Functional Pituitary Adenomas

    SciTech Connect

    Wattson, Daniel A.; Tanguturi, Shyam K.; Spiegel, Daphna Y.; Niemierko, Andrzej; Biller, Beverly M.K.; Nachtigall, Lisa B.; Bussière, Marc R.; Swearingen, Brooke; Chapman, Paul H.; Loeffler, Jay S.; Shih, Helen A.

    2014-11-01

    Purpose/Objective(s): This study evaluated the efficacy and toxicity of proton therapy for functional pituitary adenomas (FPAs). Methods and Materials: We analyzed 165 patients with FPAs who were treated at a single institution with proton therapy between 1992 and 2012 and had at least 6 months of follow-up. All but 3 patients underwent prior resection, and 14 received prior photon irradiation. Proton stereotactic radiosurgery was used for 92% of patients, with a median dose of 20 Gy(RBE). The remainder received fractionated stereotactic proton therapy. Time to biochemical complete response (CR, defined as ≥3 months of normal laboratory values with no medical treatment), local control, and adverse effects are reported. Results: With a median follow-up time of 4.3 years (range, 0.5-20.6 years) for 144 evaluable patients, the actuarial 3-year CR rate and the median time to CR were 54% and 32 months among 74 patients with Cushing disease (CD), 63% and 27 months among 8 patients with Nelson syndrome (NS), 26% and 62 months among 50 patients with acromegaly, and 22% and 60 months among 9 patients with prolactinomas, respectively. One of 3 patients with thyroid stimulating hormone—secreting tumors achieved CR. Actuarial time to CR was significantly shorter for corticotroph FPAs (CD/NS) compared with other subtypes (P=.001). At a median imaging follow-up time of 43 months, tumor control was 98% among 140 patients. The actuarial 3-year and 5-year rates of development of new hypopituitarism were 45% and 62%, and the median time to deficiency was 40 months. Larger radiosurgery target volume as a continuous variable was a significant predictor of hypopituitarism (adjusted hazard ratio 1.3, P=.004). Four patients had new-onset postradiosurgery seizures suspected to be related to generously defined target volumes. There were no radiation-induced tumors. Conclusions: Proton irradiation is an effective treatment for FPAs, and hypopituitarism remains the primary

  7. Structural characteristics of hydrated protons in the conductive channels: effects of confinement and fluorination studied by molecular dynamics simulation.

    PubMed

    Zhang, Ning; Song, Yuechun; Ruan, Xuehua; Yan, Xiaoming; Liu, Zhao; Shen, Zhuanglin; Wu, Xuemei; He, Gaohong

    2016-09-21

    The relationship between the proton conductive channel and the hydrated proton structure is of significant importance for understanding the deformed hydrogen bonding network of the confined protons which matches the nanochannel. In general, the structure of hydrated protons in the nanochannel of the proton exchange membrane is affected by several factors. To investigate the independent effect of each factor, it is necessary to eliminate the interference of other factors. In this paper, a one-dimensional carbon nanotube decorated with fluorine was built to investigate the independent effects of nanoscale confinement and fluorination on the structural properties of hydrated protons in the nanochannel using classical molecular dynamics simulation. In order to characterize the structure of hydrated protons confined in the channel, the hydrogen bonding interaction between water and the hydrated protons has been studied according to suitable hydrogen bond criteria. The hydrogen bond criteria were proposed based on the radial distribution function, angle distribution and pair-potential energy distribution. It was found that fluorination leads to an ordered hydrogen bonding structure of the hydrated protons near the channel surface, and confinement weakens the formation of the bifurcated hydrogen bonds in the radial direction. Besides, fluorination lowers the free energy barrier of hydronium along the nanochannel, but slightly increases the barrier for water. This leads to disintegration of the sequential hydrogen bond network in the fluorinated CNTs with small size. In the fluorinated CNTs with large diameter, the lower degree of confinement produces a spiral-like sequential hydrogen bond network with few bifurcated hydrogen bonds in the central region. This structure might promote unidirectional proton transfer along the channel without random movement. This study provides the cooperative effect of confinement dimension and fluorination on the structure and hydrogen

  8. Polarized and Unpolarized Structure Functions in the Valon Model

    NASA Astrophysics Data System (ADS)

    Arash, Firooz

    2006-02-01

    Hadrons are considered as the bound states of their structureful constituents, the Valons. The valon structure is calculated perturbatively in QCD; which is universal and independent of the hosting hadron. This structure is used to calculate Proton and pion structure functions. For the case of polarized structure function, the valon representation, not only gives all the available data on gp,n,d1, but also requires a sizable orbital angular momentum associated with the partonic structure of the valon.

  9. Surface, structural and tensile properties of proton beam irradiated zirconium

    NASA Astrophysics Data System (ADS)

    Rafique, Mohsin; Chae, San; Kim, Yong-Soo

    2016-02-01

    This paper reports the surface, structural and tensile properties of proton beam irradiated pure zirconium (99.8%). The Zr samples were irradiated by 3.5 MeV protons using MC-50 cyclotron accelerator at different doses ranging from 1 × 1013 to 1 × 1016 protons/cm2. Both un-irradiated and irradiated samples were characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Universal Testing Machine (UTM). The average surface roughness of the specimens was determined by using Nanotech WSxM 5.0 develop 7.0 software. The FESEM results revealed the formation of bubbles, cracks and black spots on the samples' surface at different doses whereas the XRD results indicated the presence of residual stresses in the irradiated specimens. Williamson-Hall analysis of the diffraction peaks was carried out to investigate changes in crystallite size and lattice strain in the irradiated specimens. The tensile properties such as the yield stress, ultimate tensile stress and percentage elongation exhibited a decreasing trend after irradiation in general, however, an inconsistent behavior was observed in their dependence on proton dose. The changes in tensile properties of Zr were associated with the production of radiation-induced defects including bubbles, cracks, precipitates and simultaneous recovery by the thermal energy generated with the increase of irradiation dose.

  10. Spin structure functions

    SciTech Connect

    Jian-ping Chen, Alexandre Deur, Sebastian Kuhn, Zein-eddine Meziani

    2011-06-01

    Spin-dependent observables have been a powerful tool to probe the internal structure of the nucleon and to understand the dynamics of the strong interaction. Experiments involving spin degrees of freedom have often brought out surprises and puzzles. The so-called "spin crisis" in the 1980s revealed the limitation of naive quark-parton models and led to intensive worldwide efforts, both experimental and theoretical, to understand the nucleon spin structure. With high intensity and high polarization of both the electron beam and targets, Jefferson Lab has the world's highest polarized luminosity and the best figure-of-merit for precision spin structure measurements. It has made a strong impact in this subfield of research. This chapter will highlight Jefferson Lab's unique contributions in the measurements of valence quark spin distributions, in the moments of spin structure functions at low to intermediate Q2, and in the transverse spin structure.

  11. On the electron to proton mass ratio and the proton structure

    NASA Astrophysics Data System (ADS)

    Trinhammer, Ole L.

    2013-05-01

    We derive an expression for the electron to nucleon mass ratio from a reinterpreted lattice gauge theory Hamiltonian to describe interior baryon dynamics. We use the classical electron radius as our fundamental length scale. Based on expansions on trigonometric Slater determinants for a neutral state, a specific numerical result is found to be less than three percent off the experimental value for the neutron. Via the exterior derivative on the Lie group configuration space u(3) we derive approximate parameter-free parton distribution functions that compare rather well with those for the u and d valence quarks of the proton.

  12. Characteristics of proton velocity distribution functions in the near-lunar wake from Chandrayaan-1/SWIM observations

    NASA Astrophysics Data System (ADS)

    Dhanya, M. B.; Bhardwaj, Anil; Futaana, Yoshifumi; Barabash, Stas; Alok, Abhinaw; Wieser, Martin; Holmström, Mats; Wurz, Peter

    2016-06-01

    Due to the high absorption of solar wind plasma on the lunar dayside, a large scale wake structure is formed downstream of the Moon. However, recent in-situ observations have revealed the presence of protons in the near-lunar wake (100 km to 200 km from the surface). The solar wind, either directly or after interaction with the lunar surface (including magnetic anomalies), is the source of these protons in the near-wake region. Using the entire data from the SWIM sensor of the SARA experiment onboard Chandrayaan-1, we analyzed the velocity distribution of the protons observed in the near-lunar wake. The average velocity distribution functions, computed in the solar wind rest frame, were further separated based on the angle between the upstream solar wind velocity and the IMF. Although the protons enter the wake parallel as well as perpendicular to the IMF, the velocity distribution were not identical for the different IMF orientations, indicating the control of IMF in the proton entry processes. Several proton populations were identified from the velocity distribution and their possible entry mechanism were inferred based on the characteristics of the velocity distribution. These entry mechanisms include (i) diffusion of solar wind protons into the wake along IMF, (ii) the solar wind protons with finite gyro-radii that are aided by the wake boundary electric field, (iii) solar wind protons with gyro-radii larger than lunar radii from the tail of the solar wind velocity distribution, and (iv) scattering of solar wind protons from the dayside lunar surface or from magnetic anomalies. In order to gain more insight into the entry mechanisms associated with different populations, backtracing is carried out for each of these populations. For most of the populations, the source of the protons obtained from backtracing is found to be in agreement with that inferred from the velocity distribution. There are few populations that could not be explained by the known mechanisms

  13. Proton beam writing of submicrometer structures at LIPSION

    NASA Astrophysics Data System (ADS)

    Menzel, F.; Spemann, D.; Petriconi, S.; Lenzner, J.; Butz, T.

    2007-07-01

    We report on the current status of proton beam writing (PBW) at LIPSION. At present, minimal feature sizes of 130 nm were obtained in SU-8. For this purpose 10 μm thick SU-8 was irradiated with 2.25 MeV protons under STIM conditions (˜1 fA) using a dedicated scan program. These structures have an aspect ratio of 77. However, artefacts from beam spot fluctuations and instabilities due to their large height are noticeable. Furthermore, Ni grids of different sizes and pitches were produced by electroplating. The corresponding templates were written in a negative resist called ma-N 440, which can be removed much more easily compared to SU-8 after the plating step and therefore offers the advantage of a large area Ni grow and a better control of the plating current density. This results in a higher quality concerning the homogeneity of the Ni-layer. In addition, an experimental setup for the electrochemical etching of silicon was constructed and Si structures were created by proton beam writing of Si, reaching minimal lateral dimensions of 1.2 μm.

  14. Systematic Structural Elucidation for the Protonated Form of Rare Earth Bis(porphyrinato) Double-Decker Complexes: Direct Structural Evidence of the Location of the Attached Proton.

    PubMed

    Yamashita, Ken-Ichi; Sakata, Naoya; Ogawa, Takuji

    2016-09-01

    Direct structural evidence of the presence and location of the attached proton in the protonated form of rare earth bis(porphyrinato) double-decker complexes is obtained from an X-ray diffraction study of single crystals for a series of protonated forms of bis(tetraphenylporphyrinato) complexes [M(III)(tpp)(tppH)] (M = Tb, Y, Sm, Nd, and La). When CHCl3 is used as a solvent for crystallization of the complexes, their nondisordered molecular structures are obtained and the attached proton is identified on one of the eight nitrogen atoms. Use of other solvents affords another type of crystal, in which the position of the proton is disordered and thus the molecular structure is averaged. La complex also affords the disordered average structure even when CHCl3 is used for crystallization. A variable-temperature diffraction study for the Tb complex reveals that the dynamics of the proton in the nondisordered crystal is restricted. PMID:27541189

  15. Spin Structure Functions from Electron Scattering

    SciTech Connect

    Seonho Choi

    2012-09-01

    The spin structure of the nucleon can play a key testing ground for Quantum Chromo-Dynamics (QCD) at wide kinematic ranges from smaller to large four momentum transfer Q{sup 2}. The pioneering experiments have confirmed several QCD sum rules at high Q{sup 2} where a perturbative picture holds. For a full understanding of QCD at various scales, various measurements were made at intermediate and small Q{sup 2} region and their interpretation would be a challenging task due to the non-perturbative nature. Jefferson Lab has been one of the major experimental facilities for the spin structure with its polarized electron beams and various polarized targets. A few QCD sum rules have been compared with the measured spin structure functions g{sub 1}(x, Q{sup 2}) and g{sub 2}(x, Q{sup 2}) at low Q{sup 2} and surprising results have been obtained for the spin polarizabilities, {gamma}{sub 0} and {delta}{sub LT} . As for the proton spin structure functions, the lack of data for g{sub 2}(x,Q{sup 2}) structure functions has been complemented with a new experiment at Jefferson Lab, SANE. The results from SANE will provide a better picture of the proton spin structure at a wide kinematic range in x and Q{sup 2}.

  16. Local conformational fluctuations can modulate the coupling between proton binding and global structural transitions in proteins

    PubMed Central

    Whitten, Steven T.; García-Moreno E., Bertrand; Hilser, Vincent J.

    2005-01-01

    Local conformational fluctuations in proteins can affect the coupling between ligand binding and global structural transitions. This finding was established by monitoring quantitatively how the population distribution in the ensemble of microstates of staphylococcal nuclease was affected by proton binding. Analysis of acid unfolding and proton-binding data with an ensemble-based model suggests that local fluctuations: (i) can be effective modulators of ligand-binding affinities, (ii) are important determinants of the cooperativity of ligand-driven global structural transitions, and (iii) are well represented thermodynamically as local unfolding processes. These studies illustrate how an ensemble-based description of proteins can be used to describe quantitatively the interdependence of local conformational fluctuations, ligand-binding processes, and global structural transitions. This level of understanding of the relationship between conformation, energy, and dynamics is required for a detailed mechanistic understanding of allostery, cooperativity, and other complex functional and regulatory properties of macromolecules. PMID:15767576

  17. Static and dynamic aspect of covariant density functional theory in proton rich nuclei

    SciTech Connect

    Ring, P.; Lalazissis, G. A.; Paar, N.; Vretenar, D.

    2007-11-30

    Proton rich nuclei are investigated in the framework of Covariant Density Functional Theory (CDFT). The Relativistic Hartree Bogoliubov (RHB) model is used to study the proton drip line in the region of heavy and superheavy nuclei. The dynamical behavior of nuclei with a large proton excess is studied within the Relativistic Quasiparticle Random Phase Approximation (RQRPA). Low lying El-strength is observed and it is shown that it corresponds to an oscillation of the proton skin against the isospin saturated neutron-proton core. This mode is in full analogy to the neutron pygmy resonances found in many nuclei with neutron excess.

  18. Structure of an Inward Proton-Transporting Anabaena Sensory Rhodopsin Mutant: Mechanistic Insights.

    PubMed

    Dong, Bamboo; Sánchez-Magraner, Lissete; Luecke, Hartmut

    2016-09-01

    Microbial rhodopsins are light-activated, seven-α-helical, retinylidene transmembrane proteins that have been identified in thousands of organisms across archaea, bacteria, fungi, and algae. Although they share a high degree of sequence identity and thus similarity in structure, many unique functions have been discovered and characterized among them. Some function as outward proton pumps, some as inward chloride pumps, whereas others function as light sensors or ion channels. Unique among the microbial rhodopsins characterized thus far, Anabaena sensory rhodopsin (ASR) is a photochromic sensor that interacts with a soluble 14-kDa cytoplasmic transducer that is encoded on the same operon. The sensor itself stably interconverts between all-trans-15-anti and 13-cis-15-syn retinal forms depending on the wavelength of illumination, although only the former participates in a photocycle with a signaling M intermediate. A mutation in the cytoplasmic half-channel of the protein, replacing Asp217 with Glu (D217E), results in the creation of a light-driven, single-photon, inward proton transporter. We present the 2.3 Å structure of dark-adapted D217E ASR, which reveals significant changes in the water network surrounding Glu217, as well as a shift in the carbon backbone near retinal-binding Lys210, illustrating a possible pathway leading to the protonation of Glu217 in the cytoplasmic half-channel, located 15 Å from the Schiff base. Crystallographic evidence for the protonation of nearby Glu36 is also discussed, which was described previously by Fourier transform infrared spectroscopy analysis. Finally, two histidine residues near the extracellular surface and their possible role in proton uptake are discussed. PMID:27602724

  19. Parkin structure and function

    PubMed Central

    Seirafi, Marjan; Kozlov, Guennadi; Gehring, Kalle

    2015-01-01

    Mutations in the parkin or PINK1 genes are the leading cause of the autosomal recessive form of Parkinson’s disease. The gene products, the E3 ubiquitin ligase parkin and the serine/threonine kinase PINK1, are neuroprotective proteins, which act together in a mitochondrial quality control pathway. Here, we review the structure of parkin and mechanisms of its autoinhibition and function as a ubiquitin ligase. We present a model for the recruitment and activation of parkin as a key regulatory step in the clearance of depolarized or damaged mitochondria by autophagy (mitophagy). We conclude with a brief overview of other functions of parkin and considerations for drug discovery in the mitochondrial quality control pathway. PMID:25712550

  20. Proton Transport in Imidazoles: Unraveling the Role of Supramolecular Structure

    DOE PAGESBeta

    Cosby, James T.; Holt, Adam P.; Griffin, Phillip; Wang, Yangyang; Sangoro, Joshua R.

    2015-09-18

    The impact of supramolecular hydrogen bonded networks on dynamics and charge transport in 2-ethyl-4-methylimidazole (2E4MIm), a model proton-conducting system, is investigated by broadband dielectric spectroscopy, depolarized dynamic light scattering, viscometry, and calorimetry. It is observed that the slow, Debye-like relaxation reflecting the supramolecular structure in neat 2E4MIm is eliminated upon the addition of minute amounts of levulinic acid. This is attributed to the dissociation of imidazole molecules and the breaking down of hydrogen-bonded chains, which leads to a 10-fold enhancement of ionic conductivity.

  1. Insulin structure and function.

    PubMed

    Mayer, John P; Zhang, Faming; DiMarchi, Richard D

    2007-01-01

    Throughout much of the last century insulin served a central role in the advancement of peptide chemistry, pharmacology, cell signaling and structural biology. These discoveries have provided a steadily improved quantity and quality of life for those afflicted with diabetes. The collective work serves as a foundation for the development of insulin analogs and mimetics capable of providing more tailored therapy. Advancements in patient care have been paced by breakthroughs in core technologies, such as semisynthesis, high performance chromatography, rDNA-biosynthesis and formulation sciences. How the structural and conformational dynamics of this endocrine hormone elicit its biological response remains a vigorous area of study. Numerous insulin analogs have served to coordinate structural biology and biochemical signaling to provide a first level understanding of insulin action. The introduction of broad chemical diversity to the study of insulin has been limited by the inefficiency in total chemical synthesis, and the inherent limitations in rDNA-biosynthesis and semisynthetic approaches. The goals of continued investigation remain the delivery of insulin therapy where glycemic control is more precise and hypoglycemic liability is minimized. Additional objectives for medicinal chemists are the identification of superagonists and insulins more suitable for non-injectable delivery. The historical advancements in the synthesis of insulin analogs by multiple methods is reviewed with the specific structural elements of critical importance being highlighted. The functional refinement of this hormone as directed to improved patient care with insulin analogs of more precise pharmacology is reported. PMID:17410596

  2. Effective Hyperfine-structure Functions of Ammonia

    NASA Astrophysics Data System (ADS)

    Augustovičová, L.; Soldán, P.; Špirko, V.

    2016-06-01

    The hyperfine structure of the rotation-inversion (v 2 = 0+, 0‑, 1+, 1‑) states of the 14NH3 and 15NH3 ammonia isotopomers is rationalized in terms of effective (ro-inversional) hyperfine-structure (hfs) functions. These are determined by fitting to available experimental data using the Hougen’s effective hyperfine-structure Hamiltonian within the framework of the non-rigid inverter theory. Involving only a moderate number of mass independent fitting parameters, the fitted hfs functions provide a fairly close reproduction of a large majority of available experimental data, thus evidencing adequacy of these functions for reliable prediction. In future experiments, this may help us derive spectroscopic constants of observed inversion and rotation-inversion transitions deperturbed from hyperfine effects. The deperturbed band centers of ammonia come to the forefront of fundamental physics especially as the probes of a variable proton-to-electron mass ratio.

  3. Proton electroreduction catalyzed by cobaloximes: functional models for hydrogenases.

    PubMed

    Razavet, Mathieu; Artero, Vincent; Fontecave, Marc

    2005-06-27

    Cobaloximes have been examined as electrocatalysts for proton reduction in nonaqueous solvent in the presence of triethylammonium chloride. [Co(III)(dmgH)2pyCl], working at moderate potentials (-0.90 V/(Ag/AgCl/3 mol x L(-1) NaCl) and in neutral conditions, is a promising catalyst as compared to other first-row transition metal complexes which generally function at more negative potentials and/or at lower pH. More than 100 turnovers can be achieved during controlled-potential electrolysis without detectable degradation of the catalyst. Cyclic voltammograms simulation is consistent with a heterolytic catalytic mechanism and allowed us to extract related kinetic parameters. Introduction of an electron-donating (electron-withdrawing) substituent in the axial pyridine ligand significantly increases (decreases) the rate constant of the catalytic cycle determining step. This effect linearly correlates with the Hammet coefficients of the introduced substituents. The influence of the equatorial glyoxime ligand was also investigated and the capability of the stabilized BF2-bridged species [Co(dmgBF2)2(OH2)2] for electrocatalyzed hydrogen evolution confirmed. PMID:15962987

  4. Solvation structures of protons and hydroxide ions in water

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Huang, Congcong; Waluyo, Iradwikanari; Nordlund, Dennis; Weng, Tsu-Chien; Sokaras, Dimosthenis; Weiss, Thomas; Bergmann, Uwe; Pettersson, Lars G. M.; Nilsson, Anders

    2013-04-01

    X-ray Raman spectroscopy (XRS) combined with small-angle x-ray scattering (SAXS) were used to study aqueous solutions of HCl and NaOH. Hydrated structures of H+ and OH- are not simple mirror images of each other. While both ions have been shown to strengthen local hydrogen bonds in the hydration shell as indicated by XRS, SAXS suggests that H+ and OH- have qualitatively different long-range effects. The SAXS structure factor of HCl (aq) closely resembles that of pure water, while NaOH (aq) behaves similar to NaF (aq). We propose that protons only locally enhance hydrogen bonds while hydroxide ions induce tetrahedrality in the overall hydrogen bond network of water.

  5. DNA structure and function.

    PubMed

    Travers, Andrew; Muskhelishvili, Georgi

    2015-06-01

    The proposal of a double-helical structure for DNA over 60 years ago provided an eminently satisfying explanation for the heritability of genetic information. But why is DNA, and not RNA, now the dominant biological information store? We argue that, in addition to its coding function, the ability of DNA, unlike RNA, to adopt a B-DNA structure confers advantages both for information accessibility and for packaging. The information encoded by DNA is both digital - the precise base specifying, for example, amino acid sequences - and analogue. The latter determines the sequence-dependent physicochemical properties of DNA, for example, its stiffness and susceptibility to strand separation. Most importantly, DNA chirality enables the formation of supercoiling under torsional stress. We review recent evidence suggesting that DNA supercoiling, particularly that generated by DNA translocases, is a major driver of gene regulation and patterns of chromosomal gene organization, and in its guise as a promoter of DNA packaging enables DNA to act as an energy store to facilitate the passage of translocating enzymes such as RNA polymerase. PMID:25903461

  6. Density Functional Theory Investigation of Proton Diffusion in Tungsten Oxide And Its Hydrates

    NASA Astrophysics Data System (ADS)

    Lin, Hao

    Fast proton conduction mechanism is of key importance for achieving high performance in fuel cell membranes, batteries, supercapacitors, and electrochromic materials. Enhanced proton diffusion is often observed in hydrated materials where it is thought to occur via the famous Grotthuss mechanism through pathways formed by structural water. Using first-principles calculations, we demonstrate that proton diffusion in tungsten oxide dihydrate (WO3·2H 2O), a known good proton conductor, takes place within the layers of corner-sharing WO6 octahedra without direct involvement of structural water. The calculated proton migration barrier in WO3·2H 2O is in good agreement with the experimental value inferred from the temperature dependence of conductivity. The preferred proton diffusion path in WO3·2H2O is essentially the same as in gamma-WO 3. In contrast to the small intercalation voltages calculated for WO 3 and WO3·2H2O, we find that proton absorption in the monohydrate WO3·H2O is energetically highly favorable. However, strong proton-proton repulsion limits the equilibrium H content at zero voltage. We find a fast one-dimensional diffusion channel in WO3·H2O at dilute proton concentrations, but much higher barriers are expected at near-equilibrium concentrations due to strong repulsive interactions with other protons. Our results illustrate that low proton diffusion barriers and low insertion voltages both contribute to fast proton transport in bulk WO3·2H2O and gamma-WO 3.

  7. A Proton Wire and Water Channel Revealed in the Crystal Structure of Isatin Hydrolase

    PubMed Central

    Bjerregaard-Andersen, Kaare; Sommer, Theis; Jensen, Jan K.; Jochimsen, Bjarne; Etzerodt, Michael; Morth, J. Preben

    2014-01-01

    The high resolution crystal structures of isatin hydrolase from Labrenzia aggregata in the apo and the product state are described. These are the first structures of a functionally characterized metal-dependent hydrolase of this fold. Isatin hydrolase converts isatin to isatinate and belongs to a novel family of metalloenzymes that include the bacterial kynurenine formamidase. The product state, mimicked by bound thioisatinate, reveals a water molecule that bridges the thioisatinate to a proton wire in an adjacent water channel and thus allows the proton released by the reaction to escape only when the product is formed. The functional proton wire present in isatin hydrolase isoform b represents a unique catalytic feature common to all hydrolases is here trapped and visualized for the first time. The local molecular environment required to coordinate thioisatinate allows stronger and more confident identification of orthologous genes encoding isatin hydrolases within the prokaryotic kingdom. The isatin hydrolase orthologues found in human gut bacteria raise the question as to whether the indole-3-acetic acid degradation pathway is present in human gut flora. PMID:24917679

  8. Protonation-deprotonation and structural dynamics of antidiabetic drug metformin.

    PubMed

    Hernández, Belén; Pflüger, Fernando; Kruglik, Sergei G; Cohen, Régis; Ghomi, Mahmoud

    2015-10-10

    Since the late 1950s, metformin is the worldwide first-line pharmacologic treatment for type 2 diabetes. Beyond the fact that the mode of action of this drug has always been very difficult to elucidate, little is known about its physicochemical properties in aqueous solution. Herein, we focus on the protonation-deprotonation features of metformin by using jointly Raman scattering and theoretical calculations. Vibrational markers evidence the fact that within a wide pH interval extended at either side of the physiological one, i.e. ∼7 ± 4, metformin is mainly monoprotonated. Although the biprotonated form appears as major population at very low pH values (<1.5), Raman markers of neutral species do not dominate even at very high pH values (>13), presumably because of the extreme basicity of metformin as described by recent NMR measurements. Density functional theory calculations using both explicit and implicit hydration models, have led to presume a possible coexistence of two possible monoprotonated forms in aqueous environment. In conclusion, the biophysical features of this molecule and the amount used in clinical practice might certainly explain the pleiotropic actions toward several targets where metformin could be a permanent cationic partner, a proton donor/acceptor, as well as a good candidate for stabilizing the so-called π→π interactions. PMID:26004226

  9. Angular dependence in proton-proton correlation functions in central 40Ca + 40Ca and 48Ca + 48Ca reactions

    NASA Astrophysics Data System (ADS)

    Henzl, V.; Kilburn, M. A.; Chajęcki, Z.; Henzlova, D.; Lynch, W. G.; Brown, D.; Chbihi, A.; Coupland, D. D. S.; Danielewicz, P.; Desouza, R. T.; Famiano, M.; Herlitzius, C.; Hudan, S.; Lee, Jenny; Lukyanov, S.; Rogers, A. M.; Sanetullaev, A.; Sobotka, L. G.; Sun, Z. Y.; Tsang, M. B.; Vander Molen, A.; Verde, G.; Wallace, M. S.; Youngs, M.

    2012-01-01

    The angular dependence of proton-proton correlation functions is studied in central 40Ca+40Ca and 48Ca+48Ca nuclear reactions at E/A=80 MeV. Measurements were performed with the High Resolution Array (HiRA) complemented by the 4π Array at the National Superconducting Cyclotron Laboratory. A striking angular dependence in the laboratory frame is found within proton-proton correlation functions for both systems that greatly exceeds the measured and expected isospin dependent difference between the neutron-rich and neutron-deficient systems. Sources measured at backward angles reflect the participant zone of the reaction, while much larger sources observed at forward angles reflect the expanding, fragmenting, and evaporating projectile remnants. The decrease of the size of the source with increasing momentum is observed at backward angles while a weaker trend in the opposite direction is observed at forward angles. The results are compared to the theoretical calculations using the Boltzmann-Uehling-Uhlenbeck (BUU) transport model.

  10. Multi-functional composite structures

    DOEpatents

    Mulligan, Anthony C.; Halloran, John; Popovich, Dragan; Rigali, Mark J.; Sutaria, Manish P.; Vaidyanathan, K. Ranji; Fulcher, Michael L.; Knittel, Kenneth L.

    2010-04-27

    Fibrous monolith processing techniques to fabricate multifunctional structures capable of performing more than one discrete function such as structures capable of bearing structural loads and mechanical stresses in service and also capable of performing at least one additional non-structural function.

  11. Multi-functional composite structures

    DOEpatents

    Mulligan, Anthony C.; Halloran, John; Popovich, Dragan; Rigali, Mark J.; Sutaria, Manish P.; Vaidyanathan, K. Ranji; Fulcher, Michael L.; Knittel, Kenneth L.

    2004-10-19

    Fibrous monolith processing techniques to fabricate multifunctional structures capable of performing more than one discrete function such as structures capable of bearing structural loads and mechanical stresses in service and also capable of performing at least one additional non-structural function.

  12. Neutron spin structure with polarized deuterons and spectator proton tagging at EIC

    DOE PAGESBeta

    Cosyn, W.; Guzey, V.; Higinbotham, D. W.; Hyde, C.; Kuhn, S.; Nadel-Turonski, P.; Park, K.; Sargsian, M.; Strikman, M.; Weiss, C.

    2014-10-27

    The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Thus, traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR << several 100 MeV in the nucleusmore » rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.« less

  13. Neutron spin structure with polarized deuterons and spectator proton tagging at EIC

    SciTech Connect

    Cosyn, W.; Guzey, V.; Higinbotham, D. W.; Hyde, C.; Kuhn, S.; Nadel-Turonski, P.; Park, K.; Sargsian, M.; Strikman, M.; Weiss, C.

    2014-10-27

    The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Thus, traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR << several 100 MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.

  14. Nuclear-structure effects in proton evaporation spectra

    SciTech Connect

    Sarantites, D.G.; Baktash, C.; Nicolis, N.G.; Garcia-Bermudez, G.; Abenante, V.; Beene, J.R.; Johnson, N.R.; Halbert, M.L.; Hensley, D.C.; McGowan, F.K.; Griffin, H.C.; Lee, I.Y.; Majka, Z.; Riley, M.A.; Semkow, T.M.; Stracener, D.W.; Virtanen, A. Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109)

    1990-04-30

    Energy spectra and angular distributions of evaporated protons from the reaction {sup 52}Cr({sup 34}S, 2{ital p}2{ital n}){sup 82}Sr at 130 MeV were measured in coincidence with discrete {gamma} transitions. Large shifts and changes in the shape of the proton spectra were observed when high-spin states in different rotational bands are populated. They are interpreted as due to near-yrast stretched proton emission, which preferentially populates the yrast band by subbarrier protons.

  15. Experimental moments of the nucleon structure function F2

    SciTech Connect

    Mikhail Osipenko; W. Melnitchouk; Silvano Simula; Sergey Kulagin; Giovanni Ricco

    2007-12-01

    Experimental data on the F2 structure functions of the proton and deuteron, including recent results from CLAS at Jefferson Lab, have been used to construct their n<=12 moments. A comprehensive analysis of the moments in terms of the operator product expansion has been performed to separate the moments into leading and higher twist contributions. Particular attention was paid to the issue of nuclear corrections in the deuteron, when extracting the neutron moments from data. The difference between the proton and neutron moments was compared directly with lattice QCD simulations. Combining leading twist moments of the neutron and proton we found the d/u ratio at x->1 approaching 0, although the precision of the data did not allow to exclude the 1/5 value. The higher twist components of the proton and neutron moments suggest that multi-parton correlations are isospin independent.

  16. Nuclear structure functions at small x

    SciTech Connect

    Jalilian-Marian, Jamal

    2009-11-15

    I study the nuclear structure function F{sub 2}{sup A} and its logarithmic derivative in the high-energy limit (small-x region) using the color glass condensate formalism. In this limit the structure function F{sub 2} depends on the quark-antiquark dipole-target scattering cross section N{sub F}(x{sub bj},r{sub t},b{sub t}). The same dipole cross section appears in single-hadron and hadron-photon production cross sections in the forward rapidity region in deuteron (proton)-nucleus collisions at high energy, that is, at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). I use a parametrization of the dipole cross section, which has successfully been used to describe the deuteron-gold data at the RHIC, to compute the nuclear structure function F{sub 2}{sup A} and its log Q{sup 2} derivative (which is related to gluon distribution function in the double log limit). I provide a quantitative estimate of the nuclear shadowing of F{sub 2}{sup A} and the gluon distribution function in the kinematic region relevant to a future electron-ion collider.

  17. Higher-order proton structure corrections to the Lamb shift in muonic hydrogen

    SciTech Connect

    Carlson, Carl E.; Vanderhaeghen, Marc

    2011-08-15

    The recent conundrum with the proton charge radius inspires reconsideration of the corrections that enter into determinations of the proton size. We study the two-photon proton-structure corrections, with special consideration of the nonpole subtraction term in the dispersion relation and using fits to modern data to evaluate the energy contributions. We find that individual contributions change more than the total and present results with error estimates.

  18. Hybrid Functional Calculations of Acceptor Doping in Protonic Conductor SrZrO3

    NASA Astrophysics Data System (ADS)

    Weston, Leigh; Janotti, Anderson; Cui, Xiangyuan; Stampfl, Catherine; van de Walle, Chris

    2015-03-01

    Perovskite oxides such as SrZrO3 (SZO), which exhibit high temperature proton conductivity, are promising electrolyte materials for use in solid oxide fuel cells (SOFCs). Proton conductivity in SZO is typically achieved via acceptor doping with trivalent cations substituting at the Zr site, where the formation of charge compensating oxygen vacancies facilitates proton solvation. We present a detailed study of Sc and Y dopants in SZO based on first-principles, hybrid density functional calculations. When substituting at the Zr site, both dopants form deep acceptors, where the neutral charge state forms a localized hole polaron state. Under certain growth conditions Sc and Y will form auto-compensating donor species by substituting at the Sr site, which would inhibit proton solubility. Moreover, the proton - dopant association was found to be strong, with proton binding energies of -0.41 eV and -0.31 eV for Sc Zr- and Y Zr- respectively, indicating that proton transport is limited by trapping. These new results will be useful in the development of zirconate based proton conducting electrolyte materials for solid oxide fuel cells.

  19. Ab Initio Molecular Dynamics Simulations of an Excess Proton in a Triethylene Glycol-Water Solution: Solvation Structure, Mechanism, and Kinetics.

    PubMed

    McDonnell, Marshall T; Xu, Haixuan; Keffer, David J

    2016-06-16

    We investigate the solvation shell structures, the distribution of protonic defects, mechanistic details, kinetics, and dynamics of proton transfer for an excess proton in bulk water and for an excess proton in an aqueous solution of triethylene glycol (TEG) via Car-Parrinello molecular dynamics simulations. The PW91, PBE, and PBE with the Tkatchenko-Scheffler (TS) density-dependent dispersion functionals were used and compared for bulk water and the TEG-water mixtures. The excess proton is found to reside predominantly on water molecules but also resides on hydroxyl groups of TEG. The lifetimes associated with structural diffusion time scales of the protonated water were found to be on the order of ∼1 ps. All three functionals studied support the presolvation requirement for structural diffusion. The highest level of theory shows a reduction in the free energy barrier for water-water proton transfer in TEG-water mixtures compared to bulk water. The effect of TEG shows no strong change in the kinetics for TEG-water mixtures compared to bulk water for this same level of theory. The excess proton displays burst-rest behavior in the presence of TEG, similar to that found in bulk water. We find that the TEG chain disrupts the hydrogen-bond network, causing the solvation shell around water to be populated by TEG chain groups instead of other waters, reducing the rigidity of the hydrogen-bond network. Methylene is a dominant hydrogen bond donor for the protonated water in hydrogen-bond networks associated with proton transfer and structural diffusion. This is consistent with previous studies that have found the hydronium ion to be amphiphilic in nature and to have higher proton mobility at oil-water interfaces. PMID:27218455

  20. Vortex Dust Structures in the Track Plasma of a Proton Beam

    SciTech Connect

    Fortov, V.E.; Filinov, V.S.; Vladimirov, V.I.; Deputatova, L.V.; Petrov, O.F.; Molotkov, V.I.; Rykov, V.A.; Budnik, A.P.; D'yachenko, P.P.; Rykov, K.V.; Khudyakov, A.V.

    2005-07-15

    Results are presented from experimental and theoretical investigations of the behavior of dust grains in a track plasma produced by a beam of accelerated protons. The dynamic ordered dust structures in a proton-beam-produced plasma are obtained for the first time. The processes leading to the formation of such structures are simulated numerically. The experimentally obtained dynamic vortex dust structures in a track plasma of a proton beam are explained theoretically, and the theoretical model developed to describe such a plasma is verified experimentally. Numerical investigations carried out by the method of Brownian dynamics made it possible to qualitatively explain the characteristic features of the formation of vortex dust structures.

  1. Proton Structure in High-Energy High-Multiplicity p-p Collisions

    NASA Astrophysics Data System (ADS)

    Głazek, Stanisław D.; Kubiczek, Patryk

    2016-06-01

    A few-body proton image, expected to be derivable from QCD in the renormalization group procedure for effective particles, is used within the Monte Carlo Glauber model to calculate the anisotropy coefficients in the initial collision-state of matter in high-energy high-multiplicity proton-proton interaction events. We estimate the ridge-like correlations in the final hadronic state by assuming their proportionality to the initial collision-state anisotropy. In our estimates, some distinct few-body proton structures appear capable of accounting for the magnitude of p-p ridge effect, with potentially discernible differences in dependence on multiplicity.

  2. Microdosimetry of the full slowing down of protons using Monte Carlo track structure simulations.

    PubMed

    Liamsuwan, T; Uehara, S; Nikjoo, H

    2015-09-01

    The article investigates two approaches in microdosimetric calculations based on Monte Carlo track structure (MCTS) simulations of a 160-MeV proton beam. In the first approach, microdosimetric parameters of the proton beam were obtained using the weighted sum of proton energy distributions and microdosimetric parameters of proton track segments (TSMs). In the second approach, phase spaces of energy depositions obtained using MCTS simulations in the full slowing down (FSD) mode were used for the microdosimetric calculations. Targets of interest were water cylinders of 2.3-100 nm in diameters and heights. Frequency-averaged lineal energies ([Formula: see text]) obtained using both approaches agreed within the statistical uncertainties. Discrepancies beyond this level were observed for dose-averaged lineal energies ([Formula: see text]) towards the Bragg peak region due to the small number of proton energies used in the TSM approach and different energy deposition patterns in the TSM and FSD of protons. PMID:25904698

  3. The HP-1 maquette: From an apoprotein structure to a structured hemoprotein designed to promote redox-coupled proton exchange

    PubMed Central

    Huang, Steve S.; Koder, Ronald L.; Lewis, Mitchell; Wand, A. Joshua; Dutton, P. Leslie

    2004-01-01

    Synthetic heme-binding four-α-helix bundles show promise as working model systems, maquettes, for understanding heme cofactor–protein assembly and function in oxidoreductases. Despite successful inclusion of several key functional elements of natural proteins into a family of heme protein maquettes, the lack of 3D structures, due principally to conformational heterogeneity, has prevented them from achieving their full potential. We report here the design and synthesis of HP-1, a disulfide-bridged two-α-helix peptide that self-assembles to form an antiparallel twofold symmetric diheme four-α-helix bundle protein with a stable conformation on the NMR time-scale. The HP-1 design strategy began with the x-ray crystal structure of the apomaquette L31M, an apomaquette derived from the structurally heterogeneous tetraheme-binding H10H24 prototype. L31M was functionally redesigned to accommodate two hemes ligated to histidines and to retain the strong coupling of heme oxidation-reduction to glutamate acid–base transitions and proton exchange that was characterized in molten globule predecessors. Heme insertion was modeled with angular constraints statistically derived from natural proteins, and the pattern of hydrophobic and hydrophilic residues on each helix was then altered to account for this large structural reorganization. The transition to structured holomaquette involved the alteration of 6 of 31 residues in each of the four identical helices and, unlike our earlier efforts, required no design intermediates. Oxidation-reduction of both hemes displays an unusually low midpoint potential (–248 mV vs. normal hydrogen electrode at pH 9.0), which is strongly coupled to proton binding, as designed. PMID:15056758

  4. Proton imaging of an electrostatic field structure formed in laser-produced counter-streaming plasmas

    NASA Astrophysics Data System (ADS)

    Morita, T.; Kugland, N. L.; Wan, W.; Crowston, R.; Drake, R. P.; Fiuza, F.; Gregori, G.; Huntington, C.; Ishikawa, T.; Koenig, M.; Kuranz, C.; Levy, M. C.; Martinez, D.; Meinecke, J.; Miniati, F.; Murphy, C. D.; Pelka, A.; Plechaty, C.; Presura, R.; Quirós, N.; Remington, B. A.; Reville, B.; Ross, J. S.; Ryutov, D. D.; Sakawa, Y.; Steele, L.; Takabe, H.; Yamaura, Y.; Woolsey, N.; Park, H.-S.

    2016-03-01

    We report the measurements of electrostatic field structures associated with an electrostatic shock formed in laser-produced counter-streaming plasmas with proton imaging. The thickness of the electrostatic structure is estimated from proton images with different proton kinetic energies from 4.7 MeV to 10.7 MeV. The width of the transition region is characterized by electron scale length in the laser-produced plasma, suggesting that the field structure is formed due to a collisionless electrostatic shock.

  5. Structural Influences: Cholesterol, Drug, and Proton Binding to Full-Length Influenza A M2 Protein.

    PubMed

    Ekanayake, E Vindana; Fu, Riqiang; Cross, Timothy A

    2016-03-29

    The structure and functions of the M2 protein from Influenza A are sensitive to pH, cholesterol, and the antiinfluenza drug Amantadine. This is a tetrameric membrane protein of 97 amino-acid residues that has multiple functions, among them as a proton-selective channel and facilitator of viral budding, replacing the need for the ESCRT proteins that other viruses utilize. Here, various amino-acid-specific-labeled samples of the full-length protein were prepared and mixed, so that only interresidue (13)C-(13)C cross peaks between two differently labeled proteins representing interhelical interactions are observed. This channel is activated at slightly acidic pH values in the endosome when the His(37) residues in the middle of the transmembrane domain take on a +2 or +3 charged state. Changes observed here in interhelical distances in the N-terminus can be accounted for by modest structural changes, and no significant changes in structure were detected in the C-terminal portion of the channel upon activation of the channel. Amantadine, which blocks proton conductance by binding in the aqueous pore near the N-terminus, however, significantly modifies the tetrameric structure on the opposite side of the membrane. The interactions between the juxtamembrane amphipathic helix of one monomer and its neighboring monomer observed in the absence of drug are disrupted in its presence. However, the addition of cholesterol prevents this structural disruption. In fact, strong interactions are observed between cholesterol and residues in the amphipathic helix, accounting for cholesterol binding adjacent to a native palmitoylation site and near to an interhelix crevice that is typical of cholesterol binding sites. The resultant stabilization of the amphipathic helix deep in the bilayer interface facilitates the bilayer curvature that is essential for viral budding. PMID:27028648

  6. Defect Chemistry, Oxygen Ion Conduction, and Proton Conduction of Oxides with Brownmillerite and Related Structures.

    NASA Astrophysics Data System (ADS)

    Zhang, Guobin

    This dissertation presents a study on defect structure, oxygen ion conductivity, proton conductivity, electronic conductivity, and high temperature equilibrium redox properties of brownmillerite related oxides with general formula A _{rm n}B _{rm n}O_ {rm 3n-1} (n = 2 to infty ). A defect chemistry model is proposed for the brownmillerite oxides with high oxygen ion conductivity. Ba_2 In_2O_5 was chosen as the model material and its electrical conductivity and transport properties have been studied in detail. The oxygen ion conduction above the order-disorder temperature, T_{rm d} ~ 925^circC, and a mixed ionic-electronic conduction below T _{rm d}, was studied by conductivity and EMF measurements as a function of temperature and oxygen activity. The main defects are intrinsic anion Frenkel defects below T_{rm d}, and above T_{rm d} the oxide can be treated as acceptor doped perovskite with extrinsic oxygen vacancies. Charge compensation involves only ionic defects over the whole P(O_2 ) range used in this study. The formation and mobility enthalpies of the Frenkel defects, the redox enthalpies, and the band gap have been obtained for this oxide. A similar study has been done for other compositions in Ba _{rm n}In _2Zr_{rm n-2} O_{rm 3n-1} system. The proposed model is in good agreement with the experimental results. Evidence for protonic conduction was also found in these materials, especially at low temperatures. Three regions of protonic conduction in the Arrhenius plot have been observed and analyzed. The proton formation and mobility enthalpies have been obtained. The observed proton conductivity transition at the oxygen order-disorder transition temperature directly confirms the proton formation mechanism by incorporation of H_2O molecules into oxygen vacancies. A defect chemistry study was also conducted for the brownmillerite oxides with high electronic conductivity with Ca_2(Al_{ rm x}Fe_{rm 2-x})O_5 chosen as the model system. The main defects are

  7. Toward proton MR spectroscopic imaging of stimulated brain function

    SciTech Connect

    Singh, M. . Dept. of Radiology)

    1992-08-01

    With the objective of complementing local cerebral metabolic studies of PET, and as a prelude to spectroscopic imaging, the authors have performed the first localized proton spectroscopic study of the stimulated human auditory cortex. Water suppressed localized spectroscopy (voxel size 3cm [times] 3cm [times] 3cm enclosing the auditory cortex, Te = 272ms, Tr = 3s) was performed on a 1.5T MRI/MRS system and spectra were acquired during stimulation with a 1kHz tone presented at 2Hz. Measurements were conducted for 30-40 min with a temporal resolution of 3.2 min (64 averages per time block). Results included in this paper from six subjects show a lactate peak which increases during stimulation compared to baseline values. These results suggest an increase in anaerobic glycolysis during stimulation and provide unique and valuable information that should complement glucose metabolism and flood flow studies of PET.

  8. High-x structure function of the virtually free neutron

    NASA Astrophysics Data System (ADS)

    Cosyn, Wim; Sargsian, Misak M.

    2016-05-01

    The pole extrapolation method is applied to the semi-inclusive inelastic electron scattering off the deuteron with tagged spectator protons to extract the high-x structure function of the neutron. This approach is based on the extrapolation of the measured cross sections at different momenta of the spectator proton to the nonphysical pole of the bound neutron in the deuteron. The advantage of the method is in the possibility of suppression of the nuclear effects in a maximally model-independent way. The neutron structure functions obtained in this way demonstrate a surprising x dependence at x ≥0.6 and 1.6 ≤Q2≤3.38 GeV2 , indicating a possible rise of the neutron-to-proton structure functions ratio. If the observed rise is valid in the true deep inelastic region then it may indicate new dynamics in the generation of high-x quarks in the nucleon. One such mechanism we discuss is the possible dominance of short-range isosinglet quark-quark correlations that can enhance the d -quark distribution in the proton.

  9. The Spin Structure of the Proton in the Resonance Region

    SciTech Connect

    Renee Fatemi

    2002-01-01

    Inclusive double spin asymmetries have been measured for {rvec p}({rvec e},e{prime}) using the CLAS detector and a polarized {sup 15}NH{sub 3} target at Jefferson Lab in 1998. The virtual photon asymmetry A{sub 1}, the longitudinal spin structure function, g{sub 1} (x, Q{sup 2}), and the first moment {Gamma}{sub 1}{sup p}, have been extracted for a Q{sup 2} range of 0.15-2.0 GeV{sup 2}. These results provide insight into the low Q{sup 2} evolution of spin dependent asymmetries and structure functions as well as the transition of {Gamma}{sub 1}{sup p} from the photon point, where the Gerasimov, Drell and Hearn Sum Rule is expected to be satisfied, to the deep inelastic region.

  10. Structure of light neutron-rich nuclei and mechanism of elastic proton scattering

    SciTech Connect

    Ibraeva, E. T.; Zhusupov, M. A.; Imambekov, O.

    2011-11-15

    Differential cross sections for elastic p{sup 6}He, p{sup 8}Li, and p{sup 9}Li scattering at two energies of 70 and 700 MeV per nucleon were calculated within the Glauber theory of multiple diffractive scattering. Threeparticle wave functions ({alpha}-n-n for {sup 6}He, {alpha}-t-n for {sup 8}Li, and {sup 7}Li-n-n for {sup 9}Li) were used for realistic potentials of intercluster interactions. The sensitivity of elastic scattering to proton-nucleus interaction and to the structure of nuclei was explored. In particular, the dependence of the differential cross section on the contribution of higher order collisions, on scattering on the core and peripheral nucleons, and on the contribution of small wave-function components and their asymptotic behavior was determined. A comparison with available experimental data and with the results of calculations within different formalisms was performed.

  11. Using AN Organic Scaffold to Modulate the Quantum Structure of AN Intramolecular Proton Bond: Cryogenic Vibrational Predissociation Spectroscopy of H2 on Protonated 8-NAPHTHALENE-1-AMINE

    NASA Astrophysics Data System (ADS)

    Deblase, Andrew F.; Guasco, Timothy L.; Leavitt, Christopher M.; Johnson, Mark A.; Lectka, Thomas

    2011-06-01

    The quantum structure of the intermolecular proton bond is a key aspect in understanding proton transfer events that govern the efficiency of fuel cells and various biological membranes. Previously, we have constructed a soft binding motif, that consists of a "point contact" between the lone pairs of two small molecules (combinations of ethers, alcohols, ammonia, and water) that are linked by a shared proton [Science 2007, 613, 249]. Although the frequency of the shared proton vibration has been correlated with effects of acid and base structure, such as proton affinities and dipole moments, the spatial arrangement of the proton donor and acceptor remains unexplored. Towards this aim, we have obtained a molecule of rigid topology that contains a proton donor and acceptor capable of intramolecular proton-bonding (protonated 8-flouronaphthalene-1-amine). Using electrospray ionization coupled with a novel cryogenic mass spectrometry scheme, we employ vibrational predissociation spectroscopy of H2 tagged ions to elucidate how a forced spatial configuration of the acid and base perturbs the energetics of the proton bond.

  12. Bound-state quark and gluon contributions to structure functions in QCD

    SciTech Connect

    Brodsky, S.J.

    1990-08-01

    One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic bound-valence'' and extrinsic non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs.

  13. Structured Functional Principal Component Analysis

    PubMed Central

    Shou, Haochang; Zipunnikov, Vadim; Crainiceanu, Ciprian M.; Greven, Sonja

    2015-01-01

    Summary Motivated by modern observational studies, we introduce a class of functional models that expand nested and crossed designs. These models account for the natural inheritance of the correlation structures from sampling designs in studies where the fundamental unit is a function or image. Inference is based on functional quadratics and their relationship with the underlying covariance structure of the latent processes. A computationally fast and scalable estimation procedure is developed for high-dimensional data. Methods are used in applications including high-frequency accelerometer data for daily activity, pitch linguistic data for phonetic analysis, and EEG data for studying electrical brain activity during sleep. PMID:25327216

  14. Structured functional principal component analysis.

    PubMed

    Shou, Haochang; Zipunnikov, Vadim; Crainiceanu, Ciprian M; Greven, Sonja

    2015-03-01

    Motivated by modern observational studies, we introduce a class of functional models that expand nested and crossed designs. These models account for the natural inheritance of the correlation structures from sampling designs in studies where the fundamental unit is a function or image. Inference is based on functional quadratics and their relationship with the underlying covariance structure of the latent processes. A computationally fast and scalable estimation procedure is developed for high-dimensional data. Methods are used in applications including high-frequency accelerometer data for daily activity, pitch linguistic data for phonetic analysis, and EEG data for studying electrical brain activity during sleep. PMID:25327216

  15. Functional Insights from Structural Genomics

    SciTech Connect

    Forouhar,F.; Kuzin, A.; Seetharaman, J.; Lee, I.; Zhou, W.; Abashidze, M.; Chen, Y.; Montelione, G.; Tong, L.; et al

    2007-01-01

    Structural genomics efforts have produced structural information, either directly or by modeling, for thousands of proteins over the past few years. While many of these proteins have known functions, a large percentage of them have not been characterized at the functional level. The structural information has provided valuable functional insights on some of these proteins, through careful structural analyses, serendipity, and structure-guided functional screening. Some of the success stories based on structures solved at the Northeast Structural Genomics Consortium (NESG) are reported here. These include a novel methyl salicylate esterase with important role in plant innate immunity, a novel RNA methyltransferase (H. influenzae yggJ (HI0303)), a novel spermidine/spermine N-acetyltransferase (B. subtilis PaiA), a novel methyltransferase or AdoMet binding protein (A. fulgidus AF{_}0241), an ATP:cob(I)alamin adenosyltransferase (B. subtilis YvqK), a novel carboxysome pore (E. coli EutN), a proline racemase homolog with a disrupted active site (B. melitensis BME11586), an FMN-dependent enzyme (S. pneumoniae SP{_}1951), and a 12-stranded {beta}-barrel with a novel fold (V. parahaemolyticus VPA1032).

  16. Crystal structure of the sodium–proton antiporter NhaA dimer and new mechanistic insights

    PubMed Central

    Lee, Chiara; Yashiro, Shoko; Dotson, David L.; Uzdavinys, Povilas; Iwata, So; Sansom, Mark S.P.; von Ballmoos, Christoph

    2014-01-01

    Sodium–proton antiporters rapidly exchange protons and sodium ions across the membrane to regulate intracellular pH, cell volume, and sodium concentration. How ion binding and release is coupled to the conformational changes associated with transport is not clear. Here, we report a crystal form of the prototypical sodium–proton antiporter NhaA from Escherichia coli in which the protein is seen as a dimer. In this new structure, we observe a salt bridge between an essential aspartic acid (Asp163) and a conserved lysine (Lys300). An equivalent salt bridge is present in the homologous transporter NapA, but not in the only other known crystal structure of NhaA, which provides the foundation of most existing structural models of electrogenic sodium–proton antiport. Molecular dynamics simulations show that the stability of the salt bridge is weakened by sodium ions binding to Asp164 and the neighboring Asp163. This suggests that the transport mechanism involves Asp163 switching between forming a salt bridge with Lys300 and interacting with the sodium ion. pKa calculations suggest that Asp163 is highly unlikely to be protonated when involved in the salt bridge. As it has been previously suggested that Asp163 is one of the two residues through which proton transport occurs, these results have clear implications to the current mechanistic models of sodium–proton antiport in NhaA. PMID:25422503

  17. Structure Of Rare-Earth Nuclei Around The Proton Drip Line

    SciTech Connect

    Rykaczewski, K.P.; Gross, C.J.; Yu, C.H.; Grzywacz, R.K.; Bingham, C.R.; Danchev, M.; Mazzocchi, C.; Tantawy, M.N.; Batchelder, J.C.; Karny, M.; Krolas, W.; Fong, D.; Hamilton, J.H.; Ramayya, A.V.; Piechaczek, A.; Zganjar, E.; Winger, J.A.; Ginter, T.N.; Stolz, A.; Hagino, K.

    2005-04-05

    Decay studies on rare earth nuclei around the proton drip line have been performed by means of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility in Oak Ridge. The proton emission from the odd-odd N=77 isotone 146Tm was reinvestigated, resulting in the assignment of the 1.01 MeV proton line to the decay of a short-lived 146Tm state. A new proton radioactivity of 144Tm was identified. The decays of isomeric levels in the N=77 isotones, 140Eu, 142Tb and 144Ho were remeasured using {gamma} and electron detectors. The analysis of the structure of studied nuclei, which accounts for the coupling between the protons and neutrons and for core excitations, is presented.

  18. Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS.

    PubMed

    Fatemi, R; Skabelin, A V; Burkert, V D; Crabb, D; De Vita, R; Kuhn, S E; Minehart, R; Adams, G; Anciant, E; Anghinolfi, M; Asavapibhop, B; Audit, G; Auger, T; Avakian, H; Bagdasaryan, H; Ball, J P; Barrow, S; Battaglieri, M; Beard, K; Bektasoglu, M; Bellis, M; Bertozzi, W; Bianchi, N; Biselli, A S; Boiarinov, S; Bonner, B E; Bosted, P E; Bouchigny, S; Bradford, R; Branford, D; Brooks, W K; Butuceanu, C; Calarco, J R; Carman, D S; Carnahan, B; Cetina, C; Ciciani, L; Clark, R; Cole, P L; Coleman, A; Connelly, J; Cords, D; Corvisiero, P; Crannell, H; Cummings, J P; De Sanctis, E; Degtyarenko, P V; Denizli, H; Dennis, L; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Eckhause, M; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Empl, A; Eugenio, P; Farhi, L; Feuerbach, R J; Freyberger, A; Ficenec, J; Forest, T A; Frolov, V; Funsten, H; Gaff, S J; Garçon, M; Gavalian, G; Gilad, S; Gilfoyle, G P; Giovanetti, K L; Girard, P; Gordon, C I O; Griffioen, K A; Guidal, M; Guillo, M; Guo, L; Gyurjyan, V; Hadjidakis, C; Hancock, D; Hardie, J; Heddle, D; Heimberg, P; Hersman, F W; Hicks, K; Hicks, R S; Holtrop, M; Hu, J; Hyde-Wright, C E; Ilieva, Y; Ito, M M; Jenkins, D; Joo, K; Keith, C; Kelley, J H; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Klusman, M; Kossov, M; Koubarovski, V; Kramer, L H; Kuang, Y; Kuhn, J; Lachniet, J; Laget, J M; Lawrence, D; Li, Ji; Livingston, K; Longhi, A; Lukashin, K; Major, W; Manak, J J; Marchand, C; McAleer, S; McNabb, J W C; Mecking, B A; Mehrabyan, S; Mestayer, M D; Meyer, C A; Mikhailov, K; Mirazita, M; Miskimen, R; Morand, L; Morrow, S A; Muccifora, V; Mueller, J; Mutchler, G S; Napolitano, J; Nasseripour, R; Nelson, S O; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'Brien, J T; O'Rielly, G V; Osipenko, M; Park, K; Pasyuk, E; Peterson, G; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Rock, S E; Ronchetti, F; Rossi, P; Rowntree, D; Rubin, P D; Sabatié, F; Sabourov, K; Salgado, C; Santoro, J P; Sapunenko, V; Sargsyan, M; Schumacher, R A; Seely, M; Serov, V S; Sharabian, Y G; Shaw, J; Simionatto, S; Smith, E S; Smith, T; Smith, L C; Sober, D I; Sorrel, L; Spraker, M; Stavinsky, A; Stepanyan, S; Stoler, P; Strauch, S; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Todor, L; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weller, H; Weygand, D P; Whisnant, C S; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zhang, B; Zhao, J; Zhou, Z

    2003-11-28

    Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value. PMID:14683231

  19. Structure functions and parton distributions

    SciTech Connect

    Martin, A.D.; Stirling, W.J.; Roberts, R.G.

    1995-07-01

    The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.

  20. Fine Structure in the Decay of Deformed Proton Emitters: Nonadiabatic Approach

    SciTech Connect

    Kruppa, A. T.; Barmore, B.; Nazarewicz, W.; Vertse, T. [Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, H-4001, Debrecen,

    2000-05-15

    The coupled-channel Schroedinger equation with outgoing wave boundary conditions is employed to study the fine structure seen in the proton decay of deformed even-N , odd-Z rare earth nuclei {sup 131}Eu and {sup 141}Ho . Experimental lifetimes and proton-decay branching ratios are reproduced. Variations with the standard adiabatic theory are discussed. (c) 2000 The American Physical Society.

  1. Reversible proton-switchable fluorescence controlled by conjugation effect in an organically-functionalized polyoxometalate

    PubMed Central

    Lv, Chunlin; Chen, Kun; Hu, Junjie; Zhang, Jin; Khan, Rao Naumaan Nasim; Wei, Yongge

    2016-01-01

    A novel monosubstituted organoimido hexamolybdate containing 6-nitroquinoline moiety has been successfully synthesized. This organically-functionalized polyoxometalate exhibits proton-induced switchable fluorescence property in aqueous acetonitrile solution at room temperature. Experimental and theoretical investigations of this reversible “on” and “off” switching mechanism have been carried out, and it is found that the protonation and deprotonation at the heterocyclic nitrogen atom within quinoline fragment leads to the breaking and reformation of the conjugation through strong d-π interaction between the hexamolybdate anionic cluster and the quinoline moiety, resulting in “on” and “off” luminescence signal. PMID:27321576

  2. Reversible proton-switchable fluorescence controlled by conjugation effect in an organically-functionalized polyoxometalate.

    PubMed

    Lv, Chunlin; Chen, Kun; Hu, Junjie; Zhang, Jin; Khan, Rao Naumaan Nasim; Wei, Yongge

    2016-01-01

    A novel monosubstituted organoimido hexamolybdate containing 6-nitroquinoline moiety has been successfully synthesized. This organically-functionalized polyoxometalate exhibits proton-induced switchable fluorescence property in aqueous acetonitrile solution at room temperature. Experimental and theoretical investigations of this reversible "on" and "off" switching mechanism have been carried out, and it is found that the protonation and deprotonation at the heterocyclic nitrogen atom within quinoline fragment leads to the breaking and reformation of the conjugation through strong d-π interaction between the hexamolybdate anionic cluster and the quinoline moiety, resulting in "on" and "off" luminescence signal. PMID:27321576

  3. Structural Plasticity and Hippocampal Function

    PubMed Central

    Leuner, Benedetta; Gould, Elizabeth

    2010-01-01

    The hippocampus is a region of the mammalian brain that shows an impressive capacity for structural reorganization. Preexisting neural circuits undergo modifications in dendritic complexity and synapse number, and entirely novel neural connections are formed through the process of neurogenesis. These types of structural change were once thought to be restricted to development. However, it is now generally accepted that the hippocampus remains structurally plastic throughout life. This article reviews structural plasticity in the hippocampus over the lifespan, including how it is investigated experimentally. The modulation of structural plasticity by various experiential factors as well as the possible role it may have in hippocampal functions such as learning and memory, anxiety, and stress regulation are also considered. Although significant progress has been made in many of these areas, we highlight some of the outstanding issues that remain. PMID:19575621

  4. Structural insights into the proton pumping by unusual proteorhodopsin from nonmarine bacteria.

    PubMed

    Gushchin, Ivan; Chervakov, Pavel; Kuzmichev, Pavel; Popov, Alexander N; Round, Ekaterina; Borshchevskiy, Valentin; Ishchenko, Andrii; Petrovskaya, Lada; Chupin, Vladimir; Dolgikh, Dmitry A; Arseniev, Alexander S; Arseniev, Alexander A; Kirpichnikov, Mikhail; Gordeliy, Valentin

    2013-07-30

    Light-driven proton pumps are present in many organisms. Here, we present a high-resolution structure of a proteorhodopsin from a permafrost bacterium, Exiguobacterium sibiricum rhodopsin (ESR). Contrary to the proton pumps of known structure, ESR possesses three unique features. First, ESR's proton donor is a lysine side chain that is situated very close to the bulk solvent. Second, the α-helical structure in the middle of the helix F is replaced by 3(10)- and π-helix-like elements that are stabilized by the Trp-154 and Asn-224 side chains. This feature is characteristic for the proteorhodopsin family of proteins. Third, the proton release region is connected to the bulk solvent by a chain of water molecules already in the ground state. Despite these peculiarities, the positions of water molecule and amino acid side chains in the immediate Schiff base vicinity are very well conserved. These features make ESR a very unusual proton pump. The presented structure sheds light on the large family of proteorhodopsins, for which structural information was not available previously. PMID:23872846

  5. Electron and proton absorption calculations for a graphite/epoxy composite model. [large space structures

    NASA Technical Reports Server (NTRS)

    Long, E. R., Jr.

    1979-01-01

    The Bethe-Bloch stopping power relations for inelastic collisions were used to determine the absorption of electron and proton energy in cured neat epoxy resin and the absorption of electron energy in a graphite/epoxy composite. Absorption of electron energy due to bremsstrahlung was determined. Electron energies from 0.2 to 4.0 MeV and proton energies from 0.3 to 1.75 MeV were used. Monoenergetic electron energy absorption profiles for models of pure graphite, cured neat epoxy resin, and graphite/epoxy composites are reported. A relation is determined for depth of uniform energy absorption in a composite as a function of fiber volume fraction and initial electron energy. Monoenergetic proton energy absorption profiles are reported for the neat resin model. A relation for total proton penetration in the epoxy resin as a function of initial proton energy is determined. Electron energy absorption in the composite due to bremsstrahlung is reported. Electron and proton energy absorption profiles in cured neat epoxy resin are reported for environments approximating geosynchronous earth orbit.

  6. Alpha-particles as probes of nuclear shape and structure effects in proton evaporation spectra

    SciTech Connect

    Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M. ); Baktash, C.; Beene, J.R.; Garcia-Bermudez, G.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Virtanen, A. ); Griffin, H.C. )

    1990-01-01

    The emission barriers and subbarrier anisotropies in the alpha-particle decay with respect to the spin direction on Sn and rare earth compound nuclei are examined in the light of recent calculations incorporating deformation effects in the decay process. For the Sn systems the spectral shapes and anisotropies can be examined without involving deformation. For the rare earth systems deformation which increases with spin is necessary to explain the data. Energy spectra and angular correlations of evaporated protons from the {sup 52}Cr ({sup 34}S, 2p2n){sup 82}Sr reaction were measured in coincidence with discrete transitions. Large shifts in proton spectra were observed when high spin states in different rotational bands are populated. These effects cannot be explained by statistical model calculations that do not include explicitly nuclear structure effects in the deexcitation process. They are interpreted as due to near-yrast stretched proton emission, which preferentially populates the yrast band by subbarrier protons.

  7. On the complex structural diffusion of proton holes in nanoconfined alkaline solutions within slit pores

    PubMed Central

    Muñoz-Santiburcio, Daniel; Marx, Dominik

    2016-01-01

    The hydroxide anion OH−(aq) in homogeneous bulk water, that is, the solvated proton hole, is known to feature peculiar properties compared with excess protons solvated therein. In this work, it is disclosed that nanoconfinement of such alkaline aqueous solutions strongly affects the key structural and dynamical properties of OH−(aq) compared with the bulk limit. The combined effect of the preferred hypercoordinated solvation pattern of OH−(aq), its preferred perpendicular orientation relative to the confining surfaces, the pronounced layering of nanoconfined water and the topology of the hydrogen bond network required for proton hole transfer lead to major changes of the charge transport mechanism, in such a way that the proton hole migration mechanism depends exquisitely on the width of the confined space that hosts the water film. Moreover, the anionic Zundel complex, which is of transient nature in homogeneous bulk solutions, can be dynamically trapped as a shallow intermediate species by suitable nanoconfinement conditions. PMID:27550616

  8. On the complex structural diffusion of proton holes in nanoconfined alkaline solutions within slit pores.

    PubMed

    Muñoz-Santiburcio, Daniel; Marx, Dominik

    2016-01-01

    The hydroxide anion OH(-)(aq) in homogeneous bulk water, that is, the solvated proton hole, is known to feature peculiar properties compared with excess protons solvated therein. In this work, it is disclosed that nanoconfinement of such alkaline aqueous solutions strongly affects the key structural and dynamical properties of OH(-)(aq) compared with the bulk limit. The combined effect of the preferred hypercoordinated solvation pattern of OH(-)(aq), its preferred perpendicular orientation relative to the confining surfaces, the pronounced layering of nanoconfined water and the topology of the hydrogen bond network required for proton hole transfer lead to major changes of the charge transport mechanism, in such a way that the proton hole migration mechanism depends exquisitely on the width of the confined space that hosts the water film. Moreover, the anionic Zundel complex, which is of transient nature in homogeneous bulk solutions, can be dynamically trapped as a shallow intermediate species by suitable nanoconfinement conditions. PMID:27550616

  9. Factor XIII: Structure and Function.

    PubMed

    Schroeder, Verena; Kohler, Hans P

    2016-06-01

    Over the last two decades, it became evident that factor XIII (FXIII) is not only a crucial determinant of clot characteristics but also has potentially important functions in many various fields such as bone biology, immunity, and adipogenesis. In this review, we aim to summarize the latest findings regarding structure and function of FXIII. In regard to FXIII structure, much progress has been made recently to understand how its subunits are held together. In the A subunit, the activation peptide has a crucial role in the formation of FXIII-A2 dimers. In the B subunit, Sushi domains that are involved in binding to the A subunit and in B2 dimer formation have been identified. In regard to FXIII function, interactions with immune cells and the complement system have been described. A novel function of FXIII-A in adipogenesis has been suggested. The role of FXIII-A in osteoblast differentiation has been further investigated; however, a novel double knockout mouse deficient in both FXIII-A and transglutaminase 2 showed normal bone formation. Thus, more research, in particular, into the cellular functions of FXIII-A is still required. PMID:27019464

  10. Fragmentation functions of the pion, kaon, and proton in the NLO approximation: Laplace transform approach

    NASA Astrophysics Data System (ADS)

    Zarei, M.; Taghavi-Shahri, F.; Tehrani, S. Atashbar; Sarbishei, M.

    2015-10-01

    Using the repeated Laplace transform, we find an analytical solution for Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations for extracting the pion, kaon, and proton fragmentation functions at next-to-leading-order approximation. We also study the symmetry breaking of the sea quarks fragmentation functions Dq¯ h(z ,Q2) and simply separate them according to their mass ratio. Finally, we calculate the total fragmentation functions of these hadrons and compare them with experimental data and those from global fits. Our results show a good agreement with the fragmentation functions obtained from global parametrizations as well as with the experimental data.

  11. Survey of the high resolution frequency structure of the fast magnetosonic mode and proton energy diffusion associated with these waves

    NASA Astrophysics Data System (ADS)

    Boardsen, S. A.; Hospodarsky, G. B.; Kletzing, C.; Santolik, O.; Wygant, J. R.; MacDonald, E.; Pfaff, R. F., Jr.; Kurth, W. S.; Khazanov, G. V.

    2015-12-01

    The fast magnetosonic mode, also referred to as equatorial noise, occurs at frequencies mainly between the proton cyclotron frequency (fcp) and the lower hybrid frequency. The wave properties of this mode are characterized by a strong magnetic compressional component. These waves are observed around the magnetic equator in the Earth's inner magnetosphere. Case studies of the spectra of these waves have found the emissions to be composed of 1) harmonics, usually with spacing near the local fcp, 2) broad band hiss-like structure, or 3) a superposition of the two spectral types. No statistical studies of the frequency structure of these waves have been made. Using ~600,000 burst mode wave captures from the EMFISIS Wave Form Receiver and the EFW instrument on the Van Allen Probes spacecraft this mode will be identified in the high resolution frequency spectra and its frequency structure will be characterized. The variation of the frequency structure will be investigated as a function of normalized frequency, location, and geomagnetic conditions, and with spacecraft separation. The frequency structure will be compared with path integrated gain using proton ring distributions as the wave source. Recently the modulation of the fast magnetosonic mode has been reported, with modulation periods in the range of 30s to 240s. It has been proposed that frequency drift observed during each modulation is due to strong inward diffusion in energy of the proton ring distributions that generate these waves. As the inner edge of the ring distribution diffuses towards lower energies the band of unstable harmonics increases in frequency. If in the source region, for modulations with periods greater than say 100s, the inward energy diffusion should be observable in the HOPE proton data which has a cycle time of 24s.

  12. Encapsulating Mobile Proton Carriers into Structural Defects in Coordination Polymer Crystals: High Anhydrous Proton Conduction and Fuel Cell Application.

    PubMed

    Inukai, Munehiro; Horike, Satoshi; Itakura, Tomoya; Shinozaki, Ryota; Ogiwara, Naoki; Umeyama, Daiki; Nagarkar, Sanjog; Nishiyama, Yusuke; Malon, Michal; Hayashi, Akari; Ohhara, Takashi; Kiyanagi, Ryoji; Kitagawa, Susumu

    2016-07-13

    We describe the encapsulation of mobile proton carriers into defect sites in nonporous coordination polymers (CPs). The proton carriers were encapsulated with high mobility and provided high proton conductivity at 150 °C under anhydrous conditions. The high proton conductivity and nonporous nature of the CP allowed its application as an electrolyte in a fuel cell. The defects and mobile proton carriers were investigated using solid-state NMR, XAFS, XRD, and ICP-AES/EA. On the basis of these analyses, we concluded that the defect sites provide space for mobile uncoordinated H3PO4, H2PO4(-), and H2O. These mobile carriers play a key role in expanding the proton-hopping path and promoting the mobility of protons in the coordination framework, leading to high proton conductivity and fuel cell power generation. PMID:27324658

  13. TORC2 Structure and Function.

    PubMed

    Gaubitz, Christl; Prouteau, Manoel; Kusmider, Beata; Loewith, Robbie

    2016-06-01

    The target of rapamycin (TOR) kinase functions in two multiprotein complexes, TORC1 and TORC2. Although both complexes are evolutionarily conserved, only TORC1 is acutely inhibited by rapamycin. Consequently, only TORC1 signaling is relatively well understood; and, at present, only mammalian TORC1 is a validated drug target, pursued in immunosuppression and oncology. However, the knowledge void surrounding TORC2 is dissipating. Acute inhibition of TORC2 with small molecules is now possible and structural studies of both TORC1 and TORC2 have recently been reported. Here we review these recent advances as well as observations made from tissue-specific mTORC2 knockout mice. Together these studies help define TORC2 structure-function relationships and suggest that mammalian TORC2 may one day also become a bona fide clinical target. PMID:27161823

  14. Structure and functions of angiotensinogen

    PubMed Central

    Lu, Hong; Cassis, Lisa A; Kooi, Craig W Vander; Daugherty, Alan

    2016-01-01

    Angiotensinogen (AGT) is the sole precursor of all angiotensin peptides. Although AGT is generally considered as a passive substrate of the renin–angiotensin system, there is accumulating evidence that the regulation and functions of AGT are intricate. Understanding the diversity of AGT properties has been enhanced by protein structural analysis and animal studies. In addition to whole-body genetic deletion, AGT can be regulated in vivo by cell-specific procedures, adeno-associated viral approaches and antisense oligonucleotides. Indeed, the availability of these multiple manipulations of AGT in vivo has provided new insights into the multifaceted roles of AGT. In this review, the combination of structural and functional studies is highlighted to focus on the increasing recognition that AGT exerts effects beyond being a sole provider of angiotensin peptides. PMID:26888118

  15. Structural and Electrical Characterization of Protonic Acid Doped Polyaniline

    NASA Astrophysics Data System (ADS)

    Shaktawat, Vinodini; Saxena, Narendra S.; Sharma, Kananbala; Sharma, Thaneshwar P.

    2008-04-01

    Polyaniline doped with different protonic acids were chemically synthesized using ammonium persulfate (APS) as an oxidant. These samples were characterized through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, which confirms the amorphous nature and acid doping, respectively. Electrical conduction in these samples has been studied through the measurement of I-V characteristics at room temperature as well as in the temperature range from 313 K to 413 K. So obtained characteristic curves were found to be nonlinear. The conductivity of phosphoric acid doped polyaniline sample is higher as compared to HCl doped polyaniline and pure polyaniline. Temperature dependence of conductivity suggests a semiconducting nature with increase in temperature. Activation energies have been found to be 50.86, 25.74 and 21.05 meV for pure polyaniline (base), polyaniline doped with hydrochloric, phosphoric acid, respectively.

  16. Structure and Function of Glucansucrases

    NASA Astrophysics Data System (ADS)

    Dijkstra, B. W.; Vujičić-Žagar, A.

    2008-03-01

    Glucansucrases are relatively large (~160 kDa) extracellular enzymes produced by lactic acid bacteria. Using sucrose as a substrate they synthesize high molecular mass glucose polymers, called α-glucans, which allow the bacteria to adhere to surfaces and create a biofilm. The glucan polymers are of importance for the food and dairy industry as thickening and jellying agents. An overview is given of the current insights into the structure and functioning of these and related enzymes.

  17. Proton channel models

    PubMed Central

    Pupo, Amaury; Baez-Nieto, David; Martínez, Agustín; Latorre, Ramón; González, Carlos

    2014-01-01

    Voltage-gated proton channels are integral membrane proteins with the capacity to permeate elementary particles in a voltage and pH dependent manner. These proteins have been found in several species and are involved in various physiological processes. Although their primary topology is known, lack of details regarding their structures in the open conformation has limited analyses toward a deeper understanding of the molecular determinants of their function and regulation. Consequently, the function-structure relationships have been inferred based on homology models. In the present work, we review the existing proton channel models, their assumptions, predictions and the experimental facts that support them. Modeling proton channels is not a trivial task due to the lack of a close homolog template. Hence, there are important differences between published models. This work attempts to critically review existing proton channel models toward the aim of contributing to a better understanding of the structural features of these proteins. PMID:24755912

  18. Understanding structure, function, and mutations in the mitochondrial ATP synthase

    PubMed Central

    Xu, Ting; Pagadala, Vijayakanth; Mueller, David M.

    2015-01-01

    The mitochondrial ATP synthase is a multimeric enzyme complex with an overall molecular weight of about 600,000 Da. The ATP synthase is a molecular motor composed of two separable parts: F1 and Fo. The F1 portion contains the catalytic sites for ATP synthesis and protrudes into the mitochondrial matrix. Fo forms a proton turbine that is embedded in the inner membrane and connected to the rotor of F1. The flux of protons flowing down a potential gradient powers the rotation of the rotor driving the synthesis of ATP. Thus, the flow of protons though Fo is coupled to the synthesis of ATP. This review will discuss the structure/function relationship in the ATP synthase as determined by biochemical, crystallographic, and genetic studies. An emphasis will be placed on linking the structure/function relationship with understanding how disease causing mutations or putative single nucleotide polymorphisms (SNPs) in genes encoding the subunits of the ATP synthase, will affect the function of the enzyme and the health of the individual. The review will start by summarizing the current understanding of the subunit composition of the enzyme and the role of the subunits followed by a discussion on known mutations and their effect on the activity of the ATP synthase. The review will conclude with a summary of mutations in genes encoding subunits of the ATP synthase that are known to be responsible for human disease, and a brief discussion on SNPs. PMID:25938092

  19. Measuring Form Factors and Structure Functions with CLAS

    SciTech Connect

    G.P. Gilfoyle

    2007-09-10

    The physics program at the Thomas Jefferson National Accelerator Facility includes a strong effort to measure form factors and structure functions to probe the structure of hadronic matter, reveal the nature of confinement, and develop an understanding of atomic nuclei using quark-gluon degrees of freedom. The CLAS detector is a large acceptance device occupying one of the end stations. We discuss here two programs that use CLAS; measuring the magnetic form factor of the neutron and the virtual photon asymmetry of the proton. The form factor has been measured with unprecedented kinematic coverage and precision up to Q2=4.7 GeV2 and is consistent within 5%-10% of the dipole parameterization. The proton virtual photon asymmetry has been measured across a wide range in Bjorken x. The data exceed the SU(6)-symmetric quark prediction and show evidence of a smooth approach to the scaling limit prescribed by perturbative QCD.

  20. Highly ordered surface structure of large-scale porphyrin aggregates assembled from protonated TPP and water

    NASA Astrophysics Data System (ADS)

    Udal'tsov, Alexander V.; Bolshakova, Anastasia V.; Vos, Johannes G.

    2014-05-01

    Large-scale aggregates assembled from protonated meso-tetraphenylporphine (TPP) dimers and water have been investigated by IR and resonance Raman spectroscopy and also by scanning electron microscopy (SEM). It was found that the properties of water confined in the aggregates depend on the physical state of the support. When the aggregates were deposited on a solid CaF2 plate, they showed properties consistent with a quasi-crystalline structure. But when the aggregates were dispersed in oil, their IR characteristics were different; the vibration bands of the confined water were like those of water in liquid state. A doublet at about 1000 cm-1, components of which have been attributed to specific vibrations of H3O+ and H2O bound in the structure of water-porphyrin dimeric complex, was found in IR and resonance Raman spectra (λex = 441.6 nm) of protonated TPP aggregates. This doublet indicates the hydrogen ion involving in the vibrational system of water-porphyrin dimeric complex with hydrogen bonding by similar way as in so-called Zundel cation. The resonance Raman spectrum shows evidence for proton sharing between protonated water dimer and N groups of the pyrrole rings. SEM results indicate that the large-scale aggregates of the protonated porphyrin possess highly ordered structure, are only observed when using extremely pure water.

  1. The proton FL dipole approximation in the KMR and the MRW unintegrated parton distribution functions frameworks

    NASA Astrophysics Data System (ADS)

    Modarres, M.; Masouminia, M. R.; Hosseinkhani, H.; Olanj, N.

    2016-01-01

    In the spirit of performing a complete phenomenological investigation of the merits of Kimber-Martin-Ryskin (KMR) and Martin-Ryskin-Watt (MRW) unintegrated parton distribution functions (UPDF), we have computed the longitudinal structure function of the proton, FL (x, Q2), from the so-called dipole approximation, using the LO and the NLO-UPDF, prepared in the respective frameworks. The preparation process utilizes the PDF of Martin et al., MSTW2008-LO and MSTW2008-NLO, as the inputs. Afterwards, the numerical results are undergone a series of comparisons against the exact kt-factorization and the kt-approximate results, derived from the work of Golec-Biernat and Stasto, against each other and the experimental data from ZEUS and H1 Collaborations at HERA. Interestingly, our results show a much better agreement with the exact kt-factorization, compared to the kt-approximate outcome. In addition, our results are completely consistent with those prepared from embedding the KMR and MRW UPDF directly into the kt-factorization framework. One may point out that the FL, prepared from the KMR UPDF shows a better agreement with the exact kt-factorization. This is despite the fact that the MRW formalism employs a better theoretical description of the DGLAP evolution equation and has an NLO expansion. Such unexpected consequence appears, due to the different implementation of the angular ordering constraint in the KMR approach, which automatically includes the resummation of ln ⁡ (1 / x), BFKL logarithms, in the LO-DGLAP evolution equation.

  2. Characterizing the modulation transfer functions (MTFs) of proton & carbon radiography using GEANT4 monte carlo simulations

    NASA Astrophysics Data System (ADS)

    Oumano, Michael

    Proton and carbon therapy are expanding in popularity as a clinical modality of external beam radiotherapy due to their finite range in tissue. However, patient setup, tumor tracking, and range uncertainties all continue to cause problems in delivering treatment. The development of proton/carbon radiography offers the potential to rectify all three of these problems. Imaging the patient immediately before (or even during) treatment would aid in patient setup and tumor tracking. Radiographs can also provide range information, which would reduce range uncertainties. Finally, both proton and carbon beams deliver a smaller absorbed dose to patients than their photon counterparts, when used to produce images. The aim of this study was to investigate the spatial resolution of both proton (230 MeV and 330 MeV) and carbon (400MeV/nucleon) radiography via monte carlo simulations. This was done for both cases by characterizing their modulation transfers functions (MTFs) and taking the 10% points. Our results indicate that both types of radiography yield sub-millimeter resolution and that carbon yields the better spatial resolution.

  3. Theoretical study of the structures of flavin in different oxidation and protonation states

    SciTech Connect

    Zheng, Y.J.; Ornstein, R.L.

    1996-10-02

    Ab initio molecular orbital theory was used to investigate the structure of flavin in different oxidation and protonation states using lumiflavin as a model compound. According to our study. oxidized flavin is planar no matter what its protonation state or whether it participates in hydrogen bonding. The structures of flavin semiquinone radicals are planar or very close to planar, but the reduced flavin H{sub 3}Fl{sub red} (9) is bent with a ring puckering angle of 27.3{degree} along the N5 and N10 axis. The calculations indicate that N1 is the site of protonation for oxidized flavin, which is in agreement with several crystallographic studies. The calculated spin density distribution for flavin semiquinone radicals is also consistent with experimental results. Electrostatic potential derived charges at the RHF/6-31G{sup *} level of theory are also provided for both oxidized and reduced flavins. 34 refs., 4 figs., 5 tabs.

  4. Single-proton resonant states and the isospin dependence investigated by Green’s function relativistic mean field theory

    NASA Astrophysics Data System (ADS)

    Sun, T. T.; Niu, Z. M.; Zhang, S. Q.

    2016-08-01

    The relativistic mean field theory formulated with Green’s function method (RMF-GF) is applied to investigate single-proton resonant states and isospin dependence. The calculated energies and widths for the single-proton resonant states in {}120{{Sn}} are in good agreement with previous investigations. The single-proton resonant states of the Sn isotopes and the N = 82 isotones are systematically studied and it is shown that the calculated energies and widths decrease monotonically with the increase of neutron number while increase monotonically with the increase of proton number. To further examine the evolutions of the single-proton resonant states, their dependence on the depth, radius and diffuseness of nuclear potential is investigated with the help of an analytic Woods-Saxon potential, and it is found that the increase of radius plays the most important role in the cross phenomenon appearing in the single-proton resonant states of the Sn isotopes.

  5. Structural Determinants of Arrestin Functions

    PubMed Central

    Gurevich, Vsevolod V.; Gurevich, Eugenia V.

    2015-01-01

    Arrestins are a small protein family with only four members in mammals. Arrestins demonstrate an amazing versatility, interacting with hundreds of different G protein-coupled receptor (GPCR) subtypes, numerous nonreceptor signaling proteins, and components of the internalization machinery, as well as cytoskeletal elements, including regular microtubules and centrosomes. Here, we focus on the structural determinants that mediate various arrestin functions. The receptor-binding elements in arrestins were mapped fairly comprehensively, which set the stage for the construction of mutants targeting particular GPCRs. The elements engaged by other binding partners are only now being elucidated and in most cases we have more questions than answers. Interestingly, even very limited and imprecise identification of structural requirements for the interaction with very few other proteins has enabled the development of signaling-biased arrestin mutants. More comprehensive understanding of the structural underpinning of different arrestin functions will pave the way for the construction of arrestins that can link the receptor we want to the signaling pathway of our choosing. PMID:23764050

  6. The structure and function of fungal cells

    NASA Technical Reports Server (NTRS)

    Nozawa, Y.

    1984-01-01

    The structure and function of fungal cell walls were studied with particular emphasis on dermatophytes. Extraction, isolation, analysis, and observation of the cell wall structure and function were performed. The structure is described microscopically and chemically.

  7. New nanocomposite hybrid inorganic-organic proton-conducting membranes based on functionalized silica and PTFE.

    PubMed

    Di Noto, Vito; Piga, Matteo; Giffin, Guinevere A; Negro, Enrico; Furlan, Claudio; Vezzù, Keti

    2012-09-01

    Two types of new nanocomposite proton-exchange membranes, consisting of functionalized and pristine nanoparticles of silica and silicone rubber (SR) embedded in a polytetrafluoroethylene (PTFE) matrix, were prepared. The membrane precursor was obtained from a mechanical rolling process, and the SiO₂ nanoparticles were functionalized by soaking the membranes in a solution of 2-(4-chlorosulfonylphenyl)ethyl trichlorosilane (CSPhEtCS). The membranes exhibit a highly compact morphology and a lack of fibrous PTFE. At 125 °C, the membrane containing the functionalized nanoparticles has an elastic modulus (2.2 MPa) that is higher than that of pristine Nafion (1.28 MPa) and a conductivity of 3.6×10⁻³  S cm⁻¹ despite a low proton-exchange capacity (0.11 meq g⁻¹). The good thermal and mechanical stability and conductivity at T>100 °C make these membranes a promising low-cost material for application in proton-exchange membrane fuel cells operating at temperatures higher than 100 °C. PMID:22807005

  8. High energy proton-proton elastic scattering at the Large Hadron Collider and nucleon structure

    NASA Astrophysics Data System (ADS)

    Luddy, Richard Joseph

    To gain insight into the structure of the nucleon, we pursue the development of the phenomenological model of Islam et al. (IIFS model) for high energy elastic pp and p¯p scattering. We determine the energy dependence of the parameters of the IIFS model using the available elastic differential cross section data from SPS Collider and Tevatron and the known asymptotic behavior of sigmatot (s) and rho(s) from dispersion relation calculations and more recent analyses of Cudell et al. (COMPETE Collaboration). Next, we incorporate a high energy elastic valence quark-quark scattering amplitude into the model based on BFKL pomeron to describe small impact parameter (large | t|) pp collisions. Finally, we predict the pp elastic differential cross section at the unprecedented c.m. energy of s = 14.0 TeV at the Large Hadron Collider (LHC). This prediction assumes crucial significance---because of an approved experiment at LHC: TOTal and Elastic Measurement (TOTEM). The TOTEM group plans to measure pp elastic dsigma/dt at 14.0 TeV all the way from momentum transfer |t| = 0 to |t| ≃ 10 GeV 2. Their measurement will stringently test not only the diffraction and o-exchange descriptions of the original IIFS model, but also the additional valence quark-quark scattering contribution that we find to be dominant for large |t|. Successful quantitative verification of the predicted dsigma/dt will mean that our picture of the nucleon with an outer cloud of qq¯ condensed ground state, an inner core of topological baryonic charge, and a still smaller core of massless valence quarks provides a realistic description of nucleon structure.

  9. Functional nanometer-scale structures

    NASA Astrophysics Data System (ADS)

    Chan, Tsz On Mario

    Nanometer-scale structures have properties that are fundamentally different from their bulk counterparts. Much research effort has been devoted in the past decades to explore new fabrication techniques, model the physical properties of these structures, and construct functional devices. The ability to manipulate and control the structure of matter at the nanoscale has made many new classes of materials available for the study of fundamental physical processes and potential applications. The interplay between fabrication techniques and physical understanding of the nanostructures and processes has revolutionized the physical and material sciences, providing far superior properties in materials for novel applications that benefit society. This thesis consists of two major aspects of my graduate research in nano-scale materials. In the first part (Chapters 3--6), a comprehensive study on the nanostructures based on electrospinning and thermal treatment is presented. Electrospinning is a well-established method for producing high-aspect-ratio fibrous structures, with fiber diameter ranging from 1 nm--1 microm. A polymeric solution is typically used as a precursor in electrospinning. In our study, the functionality of the nanostructure relies on both the nanostructure and material constituents. Metallic ions containing precursors were added to the polymeric precursor following a sol-gel process to prepare the solution suitable for electrospinning. A typical electrospinning process produces as-spun fibers containing both polymer and metallic salt precursors. Subsequent thermal treatments of the as-spun fibers were carried out in various conditions to produce desired structures. In most cases, polymer in the solution and the as-spun fibers acted as a backbone for the structure formation during the subsequent heat treatment, and were thermally removed in the final stage. Polymers were also designed to react with the metallic ion precursors during heat treatment in some

  10. Neutron Crystal Structure of RAS GTPase Puts in Question the Protonation State of the GTP γ-Phosphate.

    PubMed

    Knihtila, Ryan; Holzapfel, Genevieve; Weiss, Kevin; Meilleur, Flora; Mattos, Carla

    2015-12-25

    RAS GTPase is a prototype for nucleotide-binding proteins that function by cycling between GTP and GDP, with hydrogen atoms playing an important role in the GTP hydrolysis mechanism. It is one of the most well studied proteins in the superfamily of small GTPases, which has representatives in a wide range of cellular functions. These proteins share a GTP-binding pocket with highly conserved motifs that promote hydrolysis to GDP. The neutron crystal structure of RAS presented here strongly supports a protonated γ-phosphate at physiological pH. This counters the notion that the phosphate groups of GTP are fully deprotonated at the start of the hydrolysis reaction, which has colored the interpretation of experimental and computational data in studies of the hydrolysis mechanism. The neutron crystal structure presented here puts in question our understanding of the pre-catalytic state associated with the hydrolysis reaction central to the function of RAS and other GTPases. PMID:26515069

  11. How well do we know the neutron structure function?

    SciTech Connect

    J. Arrington, J. G. Rubin, W. Melnitchouk

    2012-06-01

    We present a detailed analysis of the uncertainty in the neutron F{sub 2}n structure function extracted from inclusive deuteron and proton deep-inelastic scattering data. The analysis includes experimental uncertainties as well as uncertainties associated with the deuteron wave function, nuclear smearing, and nucleon off-shell corrections. Consistently accounting for the Q{sup 2} dependence of the data and calculations, and restricting the nuclear corrections to microscopic models of the deuteron, we find significantly smaller uncertainty in the extracted F{sub 2}n/F{sub 2}p ratio than in previous analyses. In addition to yielding an improved extraction of the neutron structure function, this analysis also provides an important baseline that will allow future, model-independent extractions of neutron structure to be used to examine nuclear medium effects in the the deuteron.

  12. Understanding the proton radius puzzle: Nuclear structure effects in light muonic atoms

    NASA Astrophysics Data System (ADS)

    Ji, Chen; Hernandez, Oscar Javier; Nevo Dinur, Nir; Bacca, Sonia; Barnea, Nir

    2016-03-01

    We present calculations of nuclear structure effects to the Lamb shift in light muonic atoms. We adopt a modern ab-initio approach by combining state-of-the-art nuclear potentials with the hyperspherical harmonics method. Our calculations are instrumental to the determination of nuclear charge radii in the Lamb shift measurements, which will shed light on the proton radius puzzle.

  13. {gamma}-strength functions in {sup 60}Ni from two-step cascades following proton capture

    SciTech Connect

    Voinov, A.; Grimes, S. M.; Brune, C. R.; Massey, T. N.; Schiller, A.; Guttormsen, M.; Larsen, A. C.; Siem, S.

    2010-02-15

    The two-step cascade method previously used in neutron-capture experiments is now applied to a proton-capture reaction. The spectrum of two-step cascades populating the first 2{sup +} level of {sup 60}Ni has been measured with the {sup 59}Co(p,2{gamma}){sup 60}Ni reaction. The simulation technique used for the spectrum analysis allows one to reveal the range of possible shapes of both E1 and M1 {gamma}-strength functions. The low-energy enhancement previously observed in {sup 3}He-induced reactions is seen to appear in M1 strength functions of {sup 60}Ni.

  14. Toward a chemical mechanism of proton pumping by the B-type cytochrome c oxidases: Application of Density Functional Theory to cytochrome ba3 of Thermus thermophilus

    PubMed Central

    Fee, James A.; Case, David A.; Noodleman, Louis

    2009-01-01

    A mechanism for proton pumping by the B-type cytochrome c oxidases is presented in which one proton is pumped in conjunction with the weakly-exergonic, two-electron reduction of Fe-bound O2 to the Fe-Cu bridging peroxodianion, and three protons are pumped in conjunction with the highly-exergonic, two-electron reduction of Fe(III)-−O-O−-Cu(II) to form water and the active oxidized enzyme, Fe(III)-−OH, Cu(II). The scheme is based on the active site structure of cytochrome ba3 from Thermus thermophilus, which is considered to be both necessary and sufficient for coupled O2 reduction and proton pumping when appropriate gates are in place (not included in the model). Fourteen detailed structures obtained from DFT geometry optimization are presented that are reasonably thought to occur during the four-electron reduction of O2. Each proton pumping step takes place when a proton resides on the imidazole ring of I-His376 and the large active site cluster has a net charge of +1 due to an uncompensated, positive charge formally associated with CuB. Density functional theory (DFT) of four types was applied to determine the energy of each intermediate, and standard thermochemical approaches were used to obtain the reaction free energies for each step in the catalytic cycle. This application of DFT generally conforms with previously suggested criteria for a valid model [P. E. M. Siegbahn & M. A. R. Blomberg (2000) 100 421 - 437] and, shows how the chemistry of O2-reduction in the heme a3-CuB dinuclear center can be harnessed to generate an electrochemical proton gradient across the lipid bilayer. PMID:18928258

  15. Fine structure in proton radioactivity: An accurate tool to ascertain the breaking of axial symmetry in {sup 145}Tm

    SciTech Connect

    Arumugam, P.; Ferreira, L. S.; Maglione, E.

    2008-10-15

    With a proper formalism for proton emission from triaxially deformed nuclei, we perform exact calculations of decay widths for the decays to ground and first excited 2{sup +} states in the daughter nucleus. Our results for rotational spectrum, decay width and fine structure in the case of the nucleus {sup 145}Tm lead for the first time to an accurate identification of triaxial deformation using proton emission. This work also puts in evidence the advantage of proton emission over the conventional probes to study nuclear structure at the proton drip-line.

  16. Controlled protonation of iron-molybdenum cofactor by nitrogenase: a structural and theoretical analysis.

    PubMed Central

    Durrant, M C

    2001-01-01

    Qualitative molecular modelling has been used to identify possible routes for transfer of protons from the surface of the nitrogenase protein to the iron-molybdenum cofactor (FeMoco) and to substrates during catalysis. Three proton-transfer routes have been identified; a water-filled channel running from the protein exterior to the homocitrate ligand of FeMoco, and two hydrogen-bonded chains to specific FeMoco sulphur atoms. It is suggested that the water channel is used for multiple proton deliveries to the substrate, as well as in diffusion of products and substrates between FeMoco and the bulk solvent, whereas the two hydrogen-bonded chains each allow a single proton to be added to, and subsequently depart from, FeMoco during the catalytic cycle. Possible functional differences in the proton-transfer channels are discussed in terms of assessment of the protein environment and specific hydrogen-bonding effects. The implications of these observations are discussed in terms of the suppression of wasteful production of dihydrogen by nitrogenase and the Lowe-Thorneley scheme for dinitrogen reduction. PMID:11311117

  17. Color transparency and the structure of the proton in quantum chromodynamics

    SciTech Connect

    Brodsky, S.J.

    1989-06-01

    Many anomalies suggest that the proton itself is a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrivial proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trivial oscillatory structure. The data seems also to be suggesting that the intrinsic'' bound state structure of the proton has a non-negligible strange and charm quark content, in addition to the extrinsic'' sources of heavy quarks created in the collision itself. As we shall see in this lecture, the apparent discrepancies with experiment are not so much a failure of QCD, but rather symptoms of the complexity and richness of the theory. An important tool for analyzing this complexity is the light-cone Fock state representation of hadron wavefunctions, which provides a consistent but convenient framework for encoding the features of relativistic many-body systems in quantum field theory. 121 refs., 44 figs., 1 tab.

  18. Structure and substrate ion binding in the sodium/proton antiporter PaNhaP

    PubMed Central

    Wöhlert, David; Kühlbrandt, Werner; Yildiz, Özkan

    2014-01-01

    Sodium/proton antiporters maintain intracellular pH and sodium levels. Detailed structures of antiporters with bound substrate ions are essential for understanding how they work. We have resolved the substrate ion in the dimeric, electroneutral sodium/proton antiporter PaNhaP from Pyrococcus abyssi at 3.2 Å, and have determined its structure in two different conformations at pH 8 and pH 4. The ion is coordinated by three acidic sidechains, a water molecule, a serine and a main-chain carbonyl in the unwound stretch of trans-membrane helix 5 at the deepest point of a negatively charged cytoplasmic funnel. A second narrow polar channel may facilitate proton uptake from the cytoplasm. Transport activity of PaNhaP is cooperative at pH 6 but not at pH 5. Cooperativity is due to pH-dependent allosteric coupling of protomers through two histidines at the dimer interface. Combined with comprehensive transport studies, the structures of PaNhaP offer unique new insights into the transport mechanism of sodium/proton antiporters. DOI: http://dx.doi.org/10.7554/eLife.03579.001 PMID:25426802

  19. Role of the bound-state wave function in capture-loss rates: Slow proton in an electron gas

    SciTech Connect

    Alducin, M.; Nagy, I.

    2003-07-01

    Capture and loss rates for protons moving in an electron gas are calculated using many-body perturbation theory. The role of the form of the bound-state wave function for weakly bound states around the proton is analyzed. We find significant differences (up to a factor of 2 higher) in the values of Auger capture and loss rates when using Hulthen-type instead of hydrogenic wave functions. Its relevance in stopping power is briefly discussed.

  20. Structures and Functions of Oligosaccharins

    SciTech Connect

    Albersheim, Peter

    1995-12-01

    We have made considerable progress during the 2.5 year funding period just ending in our studies of the structures and functions of oligosaccharide signal molecules (oligosaccharins). We have emphasized studies of the enzymes that solubilize, process, and degrade oligosaccharins and of the proteins that inhibit those enzymes. We have been especially interested in elucidating how oligosaccharins and their processing enzymes participate in determining the outcome of challenges to plants by pathogenic microbes. We have studied, to a lesser extent, the roles of oligosaccharins in plant growth and development. Abstracts of papers describing results acquired with support from this grant that have been published, submitted, or in preparation are presented to summarize the progress made during the last two and one half years. The report highlights the most important contributions made in our oiigosaccharin research during this time period, and the corresponding abstract is referenced. Results of work in progress are described primarily in conjunction with our application for continued support.

  1. Functional evolution of nuclear structure

    PubMed Central

    Dawson, Scott C.

    2011-01-01

    The evolution of the nucleus, the defining feature of eukaryotic cells, was long shrouded in speculation and mystery. There is now strong evidence that nuclear pore complexes (NPCs) and nuclear membranes coevolved with the endomembrane system, and that the last eukaryotic common ancestor (LECA) had fully functional NPCs. Recent studies have identified many components of the nuclear envelope in living Opisthokonts, the eukaryotic supergroup that includes fungi and metazoan animals. These components include diverse chromatin-binding membrane proteins, and membrane proteins with adhesive lumenal domains that may have contributed to the evolution of nuclear membrane architecture. Further discoveries about the nucleoskeleton suggest that the evolution of nuclear structure was tightly coupled to genome partitioning during mitosis. PMID:22006947

  2. Interfacial Structure and Proton Conductivity of Nafion at the Pt-Deposited Surface.

    PubMed

    Ono, Yutaro; Nagao, Yuki

    2016-01-12

    Understanding the Nafion-Pt interface structure is important because fuel cell reactions occur at the three-phase boundary. Infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) technique was used to investigate the in-plane (IP) and out-of-plane (OP) spectra in the identical substrate. Our previous study revealed that the proton conductivity of the Nafion thin films decreased at the MgO and SiO2 surfaces. We proposed that the origin for the lower proton conductivity can be derived from the highly oriented structure at the interface. However, the interface structure of the Nafion-Pt interface remains unclear. In this study, Nafion thin films were prepared by spin-coating on a Pt-deposited MgO substrates. The IP spectrum exhibited a well-known spectrum, but the OP spectrum was quite differed considerably from the IP spectrum. Furthermore, thickness dependence of the degree of orientation for this OP band was observed at the Nafion-Pt interface. This OP band can be assigned as the vibration mode of the mixture of the CF2 and sulfonic acid groups. At the low-RH region, proton conductivity of the Nafion thin film on the Pt-deposited surface was 1 order of magnitude higher than that on the SiO2 surface. Furthermore, the activation energy was 0.4-0.5 eV, which is lower than that of the SiO2 surface. These results, which suggest that the Pt surface influenced the proton transport property of Nafion thin film, can contribute to understand the relationship between the proton transport property and thin film structure on the Pt-deposited surface at the three-phase boundary for fuel cells. PMID:26653839

  3. Rotavirus gene structure and function.

    PubMed Central

    Estes, M K; Cohen, J

    1989-01-01

    Knowledge of the structure and function of the genes and proteins of the rotaviruses has expanded rapidly. Information obtained in the last 5 years has revealed unexpected and unique molecular properties of rotavirus proteins of general interest to virologists, biochemists, and cell biologists. Rotaviruses share some features of replication with reoviruses, yet antigenic and molecular properties of the outer capsid proteins, VP4 (a protein whose cleavage is required for infectivity, possibly by mediating fusion with the cell membrane) and VP7 (a glycoprotein), show more similarities with those of other viruses such as the orthomyxoviruses, paramyxoviruses, and alphaviruses. Rotavirus morphogenesis is a unique process, during which immature subviral particles bud through the membrane of the endoplasmic reticulum (ER). During this process, transiently enveloped particles form, the outer capsid proteins are assembled onto particles, and mature particles accumulate in the lumen of the ER. Two ER-specific viral glycoproteins are involved in virus maturation, and these glycoproteins have been shown to be useful models for studying protein targeting and retention in the ER and for studying mechanisms of virus budding. New ideas and approaches to understanding how each gene functions to replicate and assemble the segmented viral genome have emerged from knowledge of the primary structure of rotavirus genes and their proteins and from knowledge of the properties of domains on individual proteins. Localization of type-specific and cross-reactive neutralizing epitopes on the outer capsid proteins is becoming increasingly useful in dissecting the protective immune response, including evaluation of vaccine trials, with the practical possibility of enhancing the production of new, more effective vaccines. Finally, future analyses with recently characterized immunologic and gene probes and new animal models can be expected to provide a basic understanding of what regulates the

  4. Next-to-leading-order constituent quark structure and hadronic structure functions

    NASA Astrophysics Data System (ADS)

    Arash, Firooz; Khorramian, Ali N.

    2003-04-01

    We utilize the existing next-to-leading-order (NLO) formalism to calculate the partonic structure of a constituent quark. The structure of any hadron can be obtained thereafter using a convolution method. Such a procedure is used to generate the structure functions of protons and pions in NLO, neglecting certain corrections to ΛQCD. It is shown that while the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contribution coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the SU(2) symmetry breaking of the nucleon sea and the observed violation of the Gottfried sum rule. These effects are calculated. We obtained an excellent agreement with the experimental data in a wide range of x=[10-6,1] and Q2=[0.5,5000] GeV2 for the proton structure function. We have also calculated pion structure and compared it with the existing data. Again, the model calculations agree rather well with the data from experiment.

  5. Transport properties of proton-exchange membranes: Effect of supercritical-fluid processing and chemical functionality

    NASA Astrophysics Data System (ADS)

    Pulido Ayazo

    conductivity, even with blends of these and blends with Nafion membranes. Other alternative studied was the functionalization of the membranes SIBS with metallic cations, which decreased the methanol permeability in the membranes containing the cations Mg2+, Zn2+ and Al 3+, while the proton conductivity was maintained more or less constant. The permeation of methanol vapor was investigated and the behavior through the membranes studied followed a pattern of Fick's Law, while the pattern shown by the permeation in liquid phase was non-Fickian.

  6. Airway Gland Structure and Function.

    PubMed

    Widdicombe, Jonathan H; Wine, Jeffrey J

    2015-10-01

    Submucosal glands contribute to airway surface liquid (ASL), a film that protects all airway surfaces. Glandular mucus comprises electrolytes, water, the gel-forming mucin MUC5B, and hundreds of different proteins with diverse protective functions. Gland volume per unit area of mucosal surface correlates positively with impaction rate of inhaled particles. In human main bronchi, the volume of the glands is ∼ 50 times that of surface goblet cells, but the glands diminish in size and frequency distally. ASL and its trapped particles are removed from the airways by mucociliary transport. Airway glands have a tubuloacinar structure, with a single terminal duct, a nonciliated collecting duct, then branching secretory tubules lined with mucous cells and ending in serous acini. They allow for a massive increase in numbers of mucus-producing cells without replacing surface ciliated cells. Active secretion of Cl(-) and HCO3 (-) by serous cells produces most of the fluid of gland secretions. Glands are densely innervated by tonically active, mutually excitatory airway intrinsic neurons. Most gland mucus is secreted constitutively in vivo, with large, transient increases produced by emergency reflex drive from the vagus. Elevations of [cAMP]i and [Ca(2+)]i coordinate electrolyte and macromolecular secretion and probably occur together for baseline activity in vivo, with cholinergic elevation of [Ca(2+)]i being mainly responsive for transient increases in secretion. Altered submucosal gland function contributes to the pathology of all obstructive diseases, but is an early stage of pathogenesis only in cystic fibrosis. PMID:26336032

  7. STAS Domain Structure and Function

    PubMed Central

    Sharma, Alok K.; Rigby, Alan C.; Alper, Seth L.

    2011-01-01

    Pendrin shares with nearly all SLC26/SulP anion transporters a carboxy-terminal cytoplasmic segment organized around a Sulfate Transporter and Anti-Sigma factor antagonist (STAS) domain. STAS domains of divergent amino acid sequence exhibit a conserved fold of 4 β strands interspersed among 5 α helices. The first STAS domain proteins studied were single-domain anti-sigma factor antagonists (anti-anti-σ). These anti-anti-σ indirectly stimulate bacterial RNA polymerase by inactivating inhibitory anti-σ kinases, liberating σ factors to direct specific transcription of target genes or operons. Some STAS domains are nucleotide-binding phosphoproteins or nucleotidases. Others are interaction/transduction modules within multidomain sensors of light, oxygen and other gasotransmitters, cyclic nucleotides, inositol phosphates, and G proteins. Additional multidomain STAS protein sequences suggest functions in sensing, metabolism, or transport of nutrients such as sugars, amino acids, lipids, anions, vitamins, or hydrocarbons. Still other multidomain STAS polypeptides include histidine and serine/threonine kinase domains and ligand-activated transcription factor domains. SulP/SLC26 STAS domains and adjacent sequences interact with other transporters, cytoskeletal scaffolds, and with enzymes metabolizing transported anion substrates, forming putative metabolons. STAS domains are central to membrane targeting of many SulP/SLC26 anion transporters, and STAS domain mutations are associated with at least three human recessive diseases. This review summarizes STAS domain structure and function. PMID:22116355

  8. Computer Modeling of the Earliest Cellular Structures and Functions

    NASA Astrophysics Data System (ADS)

    Pohorille, Andrew

    2000-03-01

    In the absence of extinct or extant record of protocells (the earliest ancestors of contemporary cells), the most direct way to test ourunderstanding of the origin of cellular life is to construct laboratory models of protocells. Such efforts are currently underway in the NASA Astrobiology Program. They are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures and developing designs for molecules that perform protocellular functions. Many of these functions, such as import of nutrients, capture and storage of energy, and response to changes in the environment are carried out by proteins bound to membranes. We will discuss a series of large-scale, molecular-level computer simulations which demonstrate (a) how small proteins (peptides)organize themselves into ordered structures at water-membrane interfaces and insert into membranes, (b) how these peptides aggregate to form membrane-spanning structures (e.g. channels), and (c) by what mechanisms such aggregates perform essential protocellular functions, such as proton transport of protons across cell walls, a key step in cellular bioenergetics. The simulations were performed using the molecular dynamics method, in which Newton's equations of motion for each atom in the system are solved iteratively. The problems of interest required simulations on multi-nanosecond time scales, which corresponded to 10^6-10^8 time steps.

  9. Computer Modeling of the Earliest Cellular Structures and Functions

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Chipot, Christophe; Schweighofer, Karl

    2000-01-01

    In the absence of extinct or extant record of protocells (the earliest ancestors of contemporary cells). the most direct way to test our understanding of the origin of cellular life is to construct laboratory models of protocells. Such efforts are currently underway in the NASA Astrobiology Program. They are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures and developing designs for molecules that perform proto-cellular functions. Many of these functions, such as import of nutrients, capture and storage of energy. and response to changes in the environment are carried out by proteins bound to membrane< We will discuss a series of large-scale, molecular-level computer simulations which demonstrate (a) how small proteins (peptides) organize themselves into ordered structures at water-membrane interfaces and insert into membranes, (b) how these peptides aggregate to form membrane-spanning structures (eg. channels), and (c) by what mechanisms such aggregates perform essential proto-cellular functions, such as proton transport of protons across cell walls, a key step in cellular bioenergetics. The simulations were performed using the molecular dynamics method, in which Newton's equations of motion for each item in the system are solved iteratively. The problems of interest required simulations on multi-nanosecond time scales, which corresponded to 10(exp 6)-10(exp 8) time steps.

  10. Proton stopping using a full conserving dielectric function in plasmas at any degeneracy

    SciTech Connect

    Barriga-Carrasco, Manuel D.

    2010-10-15

    In this work, we present a dielectric function including the three conservation laws (density, momentum and energy) when we take into account electron-electron collisions in a plasma at any degeneracy. This full conserving dielectric function (FCDF) reproduces the random phase approximation (RPA) and Mermin ones, which confirms this outcome. The FCDF is applied to the determination of the proton stopping power. Differences among diverse dielectric functions in the proton stopping calculation are minimal if the plasma electron collision frequency is not high enough. These discrepancies can rise up to 2% between RPA values and the FCDF ones, and to 8% between the Mermin ones and FCDF ones. The similarity between RPA and FCDF results is not surprising, as all conservation laws are also considered in RPA dielectric function. Even for plasmas with low collision frequencies, those discrepancies follow the same behavior as for plasmas with higher frequencies. Then, discrepancies do not depend on the plasma degeneracy but essentially do on the value of the plasma collision frequency.

  11. Constructing Ionic Liquid-Filled Proton Transfer Channels within Nanocomposite Membrane by Using Functionalized Graphene Oxide.

    PubMed

    Wu, Wenjia; Li, Yifan; Chen, Pingping; Liu, Jindun; Wang, Jingtao; Zhang, Haoqin

    2016-01-13

    Herein, nanocomposite membranes are fabricated based on functionalized graphene oxides (FGOs) and sulfonated poly(ether ether ketone) (SPEEK), followed by being impregnated with imidazole-type ionic liquid (IL). The functional groups (acidic group or basic group) on FGOs generate strong interfacial interactions with SPEEK chains and then adjust their motion and stacking. As a result, the nanocomposite membranes possess tunable interfacial domains as determined by its free volume characteristic, which provides regulated location for IL storage. The stored ILs act as hopping sites for water-free proton conduction along the FGO-constructed interfacial channels. The microstructure at SPEEK-FGO interface governs the IL uptake and distribution in nanocomposite membrane. Different from GO and vinyl imidazole functionalized GO (VGO), the presence of acidic (-SO3H) groups confers the p-styrenesulfonic acid functionalized GO (SGO) incorporated nanocomposite membrane loose interface and strong electrostatic attraction with imidazole-type IL, imparting an enhanced IL uptake and anhydrous proton conductivity. Nanocomposite membrane containing 7.5% SGO attains the maximum IL uptake of 73.7% and hence the anhydrous conductivity of 21.9 mS cm(-1) at 150 °C, more than 30 times that of SPEEK control membrane (0.69 mS cm(-1)). In addition, SGOs generate electrostatic attractions to the ILs confined within SGO-SPEEK interface, affording the nanocomposite membrane enhanced IL retention ability. PMID:26666712

  12. Functional and Photochemical Characterization of a Light-Driven Proton Pump from the Gammaproteobacterium Pantoea vagans.

    PubMed

    Sudo, Yuki; Yoshizawa, Susumu

    2016-05-01

    Photoactive retinal proteins are widely distributed throughout the domains of the microbial world (i.e., bacteria, archaea, and eukarya). Here we describe three retinal proteins belonging to a phylogenetic clade with a unique DTG motif. Light-induced decrease in the environmental pH and its inhibition by carbonyl cyanide m-chlorophenylhydrazone revealed that these retinal proteins function as light-driven outward electrogenic proton pumps. We further characterized one of these proteins, Pantoea vagans rhodopsin (PvR), spectroscopically. Visible spectroscopy and high-performance liquid chromatography revealed that PvR has an absorption maximum at 538 nm with the retinal chromophore predominantly in the all-trans form (>90%) under both dark and light conditions. We estimated the pKa values of the protonated Schiff base of the retinal chromophore and its counterion as approximately 13.5 and 2.1, respectively, by using pH titration experiments, and the photochemical reaction cycle of PvR was measured by time-resolved flash-photolysis in the millisecond timeframe. We observed a blue-shifted and a red-shifted intermediate, which we assigned as M-like and O-like intermediates, respectively. Decay of the M-like intermediate was highly sensitive to environmental pH, suggesting that proton uptake is coupled to decay of the M-like intermediate. From these results, we propose a putative model for the photoreaction of PvR. PMID:26970049

  13. Technique for sparing previously irradiated critical normal structures in salvage proton craniospinal irradiation

    PubMed Central

    2013-01-01

    Background Cranial reirradiation is clinically appropriate in some cases but cumulative radiation dose to critical normal structures remains a practical concern. The authors developed a simple technique in 3D conformal proton craniospinal irradiation (CSI) to block organs at risk (OAR) while minimizing underdosing of adjacent target brain tissue. Methods Two clinical cases illustrate the use of proton therapy to provide salvage CSI when a previously irradiated OAR required sparing from additional radiation dose. The prior radiation plan was coregistered to the treatment planning CT to create a planning organ at risk volume (PRV) around the OAR. Right and left lateral cranial whole brain proton apertures were created with a small block over the PRV. Then right and left lateral “inverse apertures” were generated, creating an aperture opening in the shape of the area previously blocked and blocking the area previously open. The inverse aperture opening was made one millimeter smaller than the original block to minimize the risk of dose overlap. The inverse apertures were used to irradiate the target volume lateral to the PRV, selecting a proton beam range to abut the 50% isodose line against either lateral edge of the PRV. Together, the 4 cranial proton fields created a region of complete dose avoidance around the OAR. Comparative photon treatment plans were generated with opposed lateral X-ray fields with custom blocks and coplanar intensity modulated radiation therapy optimized to avoid the PRV. Cumulative dose volume histograms were evaluated. Results Treatment plans were developed and successfully implemented to provide sparing of previously irradiated critical normal structures while treating target brain lateral to these structures. The absence of dose overlapping during irradiation through the inverse apertures was confirmed by film. Compared to the lateral X-ray and IMRT treatment plans, the proton CSI technique improved coverage of target brain tissue

  14. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

    PubMed Central

    Boughlala, Zakaria; Fonseca Guerra, Célia

    2016-01-01

    Abstract We have analyzed the structure and bonding of gas‐phase Cl−X and [HCl−X]+ complexes for X+= H+, CH3 +, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl− and HCl for the various cations. The Cl−X bond becomes longer and weaker along X+ = H+, CH3 +, Li+, and Na+. Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn–Sham molecular orbital (KS‐MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities. PMID:27551660

  15. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

    PubMed

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities. PMID:27551660

  16. A-dependence of weak nuclear structure functions

    SciTech Connect

    Haider, H.; Athar, M. Sajjad; Simo, I. Ruiz

    2015-05-15

    Effect of nuclear medium on the weak structure functions F{sub 2}{sup A}(x, Q{sup 2}) and F{sub 3}{sup A}(x, Q{sup 2}) have been studied using charged current (anti)neutrino deep inelastic scattering on various nuclear targets. Relativistic nuclear spectral function which incorporate Fermi motion, binding and nucleon correlations are used for the calculations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, F{sub i}{sup A}/F{sub i}{sup proton} and F{sub i}{sup A}/F{sub i}{sup deuteron}(i=2,3, A={sup 12}C, {sup 16}O, CH and H{sub 2}O) are obtained.

  17. Tracking the Structural and Electronic Configurations of a Cobalt Proton Reduction Catalyst in Water.

    PubMed

    Moonshiram, Dooshaye; Gimbert-Suriñach, Carolina; Guda, Alexander; Picon, Antonio; Lehmann, C Stefan; Zhang, Xiaoyi; Doumy, Gilles; March, Anne Marie; Benet-Buchholz, Jordi; Soldatov, Alexander; Llobet, Antoni; Southworth, Stephen H

    2016-08-24

    X-ray transient absorption spectroscopy (X-TAS) has been used to study the light-induced hydrogen evolution reaction catalyzed by a tetradentate macrocyclic cobalt complex with the formula [LCo(III)Cl2](+) (L = macrocyclic ligand), [Ru(bpy)3](2+) photosensitizer, and an equimolar mixture of sodium ascorbate/ascorbic acid electron donor in pure water. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analysis of a binary mixture of the octahedral Co(III) precatalyst and [Ru(bpy)3](2+) after illumination revealed in situ formation of a Co(II) intermediate with significantly distorted geometry and electron-transfer kinetics of 51 ns. On the other hand, X-TAS experiments of the complete photocatalytic system in the presence of the electron donor showed the formation of a square planar Co(I) intermediate species within a few nanoseconds, followed by its decay in the microsecond time scale. The Co(I) structural assignment is supported by calculations based on density functional theory (DFT). At longer reaction times, we observe the formation of the initial Co(III) species concomitant to the decay of Co(I), thus closing the catalytic cycle. The experimental X-ray absorption spectra of the molecular species formed along the catalytic cycle are modeled using a combination of molecular orbital DFT calculations (DFT-MO) and finite difference method (FDM). These findings allowed us to assign the full mechanistic pathway, followed by the catalyst as well as to determine the rate-limiting step of the process, which consists in the protonation of the Co(I) species. This study provides a complete kinetics scheme for the hydrogen evolution reaction by a cobalt catalyst, revealing unique information for the development of better catalysts for the reductive side of hydrogen fuel cells. PMID:27452370

  18. Proton-insertion-enhanced pseudocapacitance based on the assembly structure of tungsten oxide.

    PubMed

    Zhu, Minshen; Meng, Wenjun; Huang, Yan; Huang, Yang; Zhi, Chunyi

    2014-11-12

    The capacitances of supercapacitors with carbon and metal oxides as electrodes are usually associated with the available surface areas of the electrode materials. However, in this paper, we report that proton insertion, an unusual capacitive mechanism, may effectively enhance the capacitance of metal oxides with low surface area but specific structures. Tungsten trioxide (WO3) as the electrode material for supercapacitors has always suffered from low capacitance. Nevertheless, enhanced by the proton insertion mechanism, we demonstrate that electrodes fabricated by an assembly structure of hexagonal-phase WO3 (h-WO3) nanopillars achieve a high capacitance of up to 421.8 F g(-1) under the current density of 0.5 A g(-1), which is the highest capacitance achieved with pure WO3 as the electrodes so far, to the best of our knowledge. Detailed analyses indicate that proton insertion dominates the electrochemical behavior of h-WO3 and plays the key role in reaching high capacitance by excluding other mechanisms. In addition, a thorough investigation on the temperature-dependent electrochemical performance reveals excellent performance stability at different temperatures. This study provides a new approach to achieving high capacitance by effective proton insertion into ordered tunnels in crystallized metal oxides, which is primarily important for the fabrication of compact high-performance energy storage devices. PMID:25280251

  19. Effect of a tensor force on the proton bubble structure of 206Hg

    NASA Astrophysics Data System (ADS)

    Wang, Y. Z.; Hou, Z. Y.; Zhang, Q. L.; Tian, R. L.; Gu, J. Z.

    2015-01-01

    The proton density distribution of 206Hg is calculated in the framework of the Skyrme-Hartree-Fock approach with the SLy5, SLy5 + T, and SLy5 + Tw interactions. It is shown that the central density drops strongly with the SLy5 and SLy5 + T interactions due to the vacancy of the 3 s1 /2 orbital. This means that the density depression in the interior of the nucleus is not so much influenced by the tensor force of the SLy5 + T interaction. However, with the SLy5 + Tw interaction the bubble structure does not exist because the tensor force effect of this interaction leads to the inversion between the single-proton states 3 s1 /2 and 1 h11 /2 (3 s1 /2-1 h11 /2 inversion) so that the 3 s1 /2 state is fully occupied by protons. In addition, a detailed discussion on the antibubble effect from the pairing interaction is performed by using the Skyrme-Hartree-Fock-Bogoliubov approach. It is found that a proton bubble structure in 206Hg is unlikely to appear because of the paring correlation.

  20. Protonation of Glu135 Facilitates the Outward-to-Inward Structural Transition of Fucose Transporter

    PubMed Central

    Liu, Yufeng; Ke, Meng; Gong, Haipeng

    2015-01-01

    Major facilitator superfamily (MFS) transporters typically need to alternatingly sample the outward-facing and inward-facing conformations, in order to transport the substrate across membrane. To understand the mechanism, in this work, we focused on one MFS member, the L-fucose/H+ symporter (FucP), whose crystal structure exhibits an outward-open conformation. Previous experiments imply several residues critical to the substrate/proton binding and structural transition of FucP, among which Glu135, located in the periplasm-accessible vestibule, is supposed as being involved in both proton translocation and conformational change of the protein. Here, the structural transition of FucP in presence of substrate was investigated using molecular-dynamics simulations. By combining the equilibrium and accelerated simulations as well as thermodynamic calculations, not only was the large-scale conformational change from the outward-facing to inward-facing state directly observed, but also the free energy change during the structural transition was calculated. The simulations confirm the critical role of Glu135, whose protonation facilitates the outward-to-inward structural transition both by energetically favoring the inward-facing conformation in thermodynamics and by reducing the free energy barrier along the reaction pathway in kinetics. Our results may help the mechanistic studies of both FucP and other MFS transporters. PMID:26244736

  1. Identification of the sulfoxide functionality in protonated analytes via ion/molecule reactions in linear quadrupole ion trap mass spectrometry.

    PubMed

    Sheng, Huaming; Williams, Peggy E; Tang, Weijuan; Zhang, Minli; Kenttämaa, Hilkka I

    2014-09-01

    A mass spectrometric method utilizing gas-phase ion/molecule reactions of 2-methoxypropene (MOP) has been developed for the identification of the sulfoxide functionality in protonated analytes in a LQIT mass spectrometer. Protonated sulfoxide analytes react with MOP to yield an abundant addition product (corresponding to 37-99% of the product ions), which is accompanied by a much slower proton transfer. The total efficiency (percent of gas-phase collisions leading to products) of the reaction is moderate (3-14%). A variety of compounds with different functional groups, including sulfone, hydroxylamino, N-oxide, aniline, phenol, keto, ester, amino and hydroxy, were examined to probe the selectivity of this reaction. Most of the protonated compounds with proton affinities lower than that of MOP react mainly via proton transfer to MOP. The formation of adduct-MeOH ions was found to be characteristic for secondary N-hydroxylamines. N-Oxides formed abundant MOP adducts just like sulfoxides, but sulfoxides can be differentiated from N-oxides based on their high reaction efficiencies. The reaction was tested by using the anti-inflammatory drug sulindac (a sulfoxide) and its metabolite sulindac sulfone. The presence of a sulfoxide functionality in the drug but a sulfone functionality in the metabolite was readily demonstrated. The presence of other functionalities in addition to sulfoxide in the analytes was found not to influence the diagnostic reactivity. PMID:24968187

  2. Structure and functions of fungal cell surfaces

    NASA Technical Reports Server (NTRS)

    Nozawa, Y.

    1984-01-01

    A review with 24 references on the biochemistry, molecular structure, and function of cell surfaces of fungi, especially dermatophytes: the chemistry and structure of the cell wall, the effect of polyene antibiotics on the morphology and function of cytoplasmic membranes, and the chemical structure and function of pigments produced by various fungi are discussed.

  3. Research of nanocomposite structure of boron nitride at proton radiation

    NASA Astrophysics Data System (ADS)

    Borodin, Y. V.; Ermolaev, D. S.; Pak, V.; Zhang, K.

    2016-02-01

    Using roentgen diffraction and electron microscopy, the influence of nanosecond irradiation by ion beams of high energy on forming of self-organized nanoblocks in near surface's layers of boron nitride (BN) has been studied. It was shown that low temperature transitions from hexagonal to wrutz boron nitrides is associated with changes of shape and sizes of self-organized particles consisting the nanoblocks. We have calculated the parameters of nanoblocks using the meanings of interplane distances and properties of subreflexes orders. The collective shifting deformations of layers in nanoblocks provides phase transition under the screen and forming the set of nanotubes with escaping of five order axes of symmetry. It has been realized that pentagons and stars arranged in points of entrance of five order axis of symmetry are associated with peculiarity of self-organization of the spiral-cyclic structures.

  4. Next-to leading order analysis of target mass corrections to structure functions and asymmetries

    SciTech Connect

    L. T. Brady, A. Accardi, T. J. Hobbs, W. Melnitchouk

    2011-10-01

    We perform a comprehensive analysis of target mass corrections (TMCs) to spin-averaged structure functions and asymmetries at next-to-leading order. Several different prescriptions for TMCs are considered, including the operator product expansion, and various approximations to it, collinear factorization, and xi-scaling. We assess the impact of each of these on a number of observables, such as the neutron to proton F{sub 2} structure function ratio, and parity-violating electron scattering asymmetries for protons and deuterons which are sensitive to gamma-Z interference effects. The corrections from higher order radiative and nuclear effects on the parity-violating deuteron asymmetry are also quantified.

  5. Next-to-leading order analysis of target mass corrections to structure functions and asymmetries

    SciTech Connect

    Brady, L. T.; Accardi, A.; Hobbs, T. J.; Melnitchouk, W.

    2011-10-01

    We perform a comprehensive analysis of target mass corrections to spin-averaged structure functions and asymmetries at next-to-leading order. Several different prescriptions for target mass corrections are considered, including the operator product expansion, and various approximations to it, collinear factorization, and {xi}-scaling. We assess the impact of each of these on a number of observables, such as the neutron to proton F{sub 2} structure function ratio, and parity-violating electron scattering asymmetries for protons and deuterons which are sensitive to {gamma}Z interference effects. The corrections from higher order radiative and nuclear effects on the parity-violating deuteron asymmetry are also quantified.

  6. Study of structure-activity relationship of enantiomeric, protonated and deprotonated forms of warfarin via vibrational spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Mishra, Alok; Srivastava, Sunil Kumar; Swati, D.

    2013-09-01

    The structure-activity relationship of the anticoagulant drug warfarin were studied by studying two enantiomeric forms (S-form and R-form) of warfarin and its protonated as well as deprotonated structures in aqueous media using density functional theory (DFT). Theoretically computed Raman and IR spectra of all the computed structures were compared and their specific vibrational spectroscopic signatures were discussed. The percentage contributions of individual normal modes of warfarin, which provides direct evidence of the different molecular activity due to change in relative atomic position of atoms in molecule, were investigated through potential energy distribution (PED). The optimized energy and molecular electrostatic potential (MEP) maps show that the S-form of the drug molecules warfarin is energetically more stable than R-form and provides higher docking opportunity for the molecular binding with the receptors in the bio-systems.

  7. Synthetic Models for the [FeFe]-Hydrogenase: Catalytic Proton Reduction and the Structure of the Doubly Protonated Intermediate

    PubMed Central

    Carroll, Maria E.; Barton, Bryan E.; Rauchfuss, Thomas B.; Carroll, Patrick J.

    2012-01-01

    This report compares biomimetic HER catalysts with and without the amine cofactor (adtNH): Fe2(adtNH)(CO)2(dppv)2 (1NH) and Fe2(pdt)(CO)2(dppv)2 (2; (adtNH)2− = (HN(CH2S)22−, pdt2− = 1,3-(CH2)3S22−). These compounds are spectroscopically, structurally, and stereodynamically very similar but exhibit very different catalytic properties. Protonation of 1NH and 2 each give three isomeric hydrides beginning with the kinetically favored terminal hydride, which converts sequentially to sym and unsym isomers of the bridging hydrides. In the case of the amine, the corresponding ammonium-hydrides are also observed. In the case of the terminal amine hydride [t-H1NH]BF4, the ammonium/amine-hydride equilibrium is sensitive to counteranions and solvent. The species [t-H1NH2](BF4)2 represents the first example of a crystallographically characterized terminal hydride produced by protonation. The NH--HFe distance of 1.88(7) Å indicates dihydrogen bonding. The bridging hydrides [µ-H1NH]+ and [µ-H2]+ reduce near −1.8 V, about 150 mV more negative than the reductions of the terminal hydride [t-H1NH]+ and [t-H2]+ at −1.65 V. Reductions of the amine hydrides [t-H1NH]+ and [t-H1NH2]2+ are irreversible. For the pdt analog, the [t-H2]+/0 couple is unaffected by weak acids (pKaMeCN 15.3) but exhibits catalysis with HBF4•Et2O, albeit with a TOF around 4 s−1 and an overpotential greater than 1 V. The voltammetry of [t-H1NH]+ is strongly affected by relatively weak acids and proceeds at 5000 s−1 with an overpotential of 0.7 V. The ammonium-hydride [t-H1NH2]2+ is a faster catalyst with an estimated TOF of 58,000 s−1 and an overpotential of 0.5 V. PMID:23126330

  8. Reinvestigation of the Structure of Protonated Lysine Dimer

    NASA Astrophysics Data System (ADS)

    Kong, Xianglei

    2014-03-01

    To better understand inconsistencies between the predicted infrared (IR) spectra of previously suggested isomers of Lys2H+ reported by Wu et al. (J. Am. Soc. Mass Spectrom. 22:1651-1659, 18) and the experimental IR photon dissociation (IRPD) spectrum obtained by Oh et al. (J. Am. Chem. Soc. 127:4076-4083, 4), the structure of Lys2H+ was reinvestigated using IRPD spectroscopy in the extended region 2700-3700 cm-1 and theoretical calculations. The new experimental IRPD spectrum is in good agreement with Oh's spectrum in the corresponding wavelength range. Based on calculations at the MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p) and MP2/6-31 + G(d,p)//MP2/6-31 + G(d,p) levels, a new salt-bridged isomer, ZW1, was found to be the most stable isomer; it is more energetically favored than the previously suggested charge-solvated isomer LL-CS01 by 10 or 26 kJ mol-1. Although the calculated IR spectrum of ZW1 is in good agreement with the experimental one in the range 2700-3700 cm-1, it is in poor agreement with the previous IRPD spectrum in the range 1000-1900 cm-1. This investigation shows that the intermolecular interactions inside the dimer are more complex than previously supposed. It is possible that both salt-bridged and charge-solvated isomers of Lys2H+ are stable in the gas phase, and the isomers generated during ionization are sensitive to the experimental conditions.

  9. Density functional investigation of photo induced Intramolecular Proton Transfer (IPT) in Indole-7-carboxaldehyde and its experimental verification

    NASA Astrophysics Data System (ADS)

    Singla, Nidhi; Chowdhury, Papia

    2013-08-01

    A detail theoretical study has been performed using Density functional theory (DFT) and Time dependent DFT (TDDFT) to investigate the Intramolecular Proton Transfer (IPT) mechanism in Indole-7-carboxaldehyde (I7C) from its normal (I*) to zwitterion (II*) form. B3LYP/6-311++G (d, p) basis set has been used to obtain structural parameters and relative energies in the ground state (S0) and excited state (S1). Atoms in Molecules (AIMs), Mulliken and Natural bond orbitals (NBOs) analysis proves the existence of intramolecular hydrogen bonding (IHB). The electron density (ρ) at Bond critical points (BCPs) on a hydrogen bridge (N15sbnd H12⋯O18) certify IHB and possibility of IPT from acidic (N15sbnd H12) to basic (lbond2 C16dbnd O18) group and creation of II*. Transition state (TS) with dual minima in the Potential energy surface (PES) confirms the I* → TS → II* transition due to excited state Intramolecular Proton Transfer (ESIPT). Photo-physical pathway from I* → II* agrees well with computed/experimental emission peaks.

  10. A divergent route to core- and peripherally functionalized diazacoronenes that act as colorimetric and fluorescence proton sensors

    SciTech Connect

    He, Bo; Dai, Jing; Zherebetskyy, Danylo; Chen, Teresa L.; Zhang, Benjamin A.; Teat, Simon J.; Zhang, Qichun; Wang, Linwang; Liu, Yi

    2015-03-31

    Combining core annulation and peripheral group modification, we have demonstrated a divergent synthesis of a family of highly functionalized coronene derivatives from a readily accessible dichlorodiazaperylene intermediate. Various reactions, such as aromatic nucleophilic substitution, Kumada coupling and Suzuki coupling proceed effectively on α-positions of the pyridine sites, giving rise to alkoxy, thioalkyl, alkyl or aryl substituted polycyclic aromatic hydrocarbons. In addition to peripheral group modulation, the aromatic core structures can be altered by annulation with thiophene or benzene ring systems. Corresponding single crystal X-ray diffraction and optical studies indicate that the heteroatom linkages not only impact the solid state packing, but also significantly influence the optoelectronic properties. Moreover, these azacoronene derivatives display significant acid-induced spectroscopic changes, suggesting their great potential as colorimetric and fluorescence proton sensors.

  11. A divergent route to core- and peripherally functionalized diazacoronenes that act as colorimetric and fluorescence proton sensors

    DOE PAGESBeta

    He, Bo; Dai, Jing; Zherebetskyy, Danylo; Chen, Teresa L.; Zhang, Benjamin A.; Teat, Simon J.; Zhang, Qichun; Wang, Linwang; Liu, Yi

    2015-03-31

    Combining core annulation and peripheral group modification, we have demonstrated a divergent synthesis of a family of highly functionalized coronene derivatives from a readily accessible dichlorodiazaperylene intermediate. Various reactions, such as aromatic nucleophilic substitution, Kumada coupling and Suzuki coupling proceed effectively on α-positions of the pyridine sites, giving rise to alkoxy, thioalkyl, alkyl or aryl substituted polycyclic aromatic hydrocarbons. In addition to peripheral group modulation, the aromatic core structures can be altered by annulation with thiophene or benzene ring systems. Corresponding single crystal X-ray diffraction and optical studies indicate that the heteroatom linkages not only impact the solid state packing,more » but also significantly influence the optoelectronic properties. Moreover, these azacoronene derivatives display significant acid-induced spectroscopic changes, suggesting their great potential as colorimetric and fluorescence proton sensors.« less

  12. Polarized Structure Function of Nucleon and Orbital Angular Momentum

    NASA Astrophysics Data System (ADS)

    Arash, Firooz; Taghavi-Shahri, Fatemeh

    2007-06-01

    We have utilized the concept of valon model to calculate the spin structure function of a constituent quark. This structure is universal and arises from perturbative dressing of a valence quark in QCD. With a convolution method the polarized structure functions of proton, neutron, and deuteron are obtained. Our results agree rather well with all available experimental data. It suggests that the sea quark contribution to the spin of nucleon is consistent with zero, in agreement with HERMES data. It also reveals that while the total quark contribution to the spin of a constituent quark, or valon, is almost constant and equal to one, the gluon contribution grows with the increase of Q2, and hence, requiring a sizable negative angular momentum contribution. This component, as well as singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD. We speculate that the gluon contribution to the spin of proton is in the order of 50%. Furthermore, we have determined the polarized valon distribution in a nucleon.

  13. Investigation of the structure of light exotic nuclei by proton elastic scattering in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V.; Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.

    2015-05-01

    In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the 6He, 8He, 11Li, and 14Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the 8Li, 9Li, and 12Be nuclei.

  14. Proton Quark Helicity Structure via W-Boson Production in PP Collision @ Phenix

    NASA Astrophysics Data System (ADS)

    Giordano, F.

    2016-02-01

    The spin structure of the proton has been long studied in the past decades, but, while the contributions to the proton spin from valence quarks is by now precisely known, large uncertainties are still affecting our knowledge of the sea quark contributions. The measurement of single-spin asymmetries of the parity violating W production in pp collision allows a (quasi-)model independent access to the flavor-dependent light sea quark contributions. Being maximally parity violating, the W charge can be directly realted to the quark and antiquark flavor, and in addition, moving from forward to backward rapidities with respect to the polarized proton beam direction it is possible to change the relative contributions of u, d, anti-u, anti-d quarks, thus accessing each light-quark spin alignment with respect to the proton spin. At PHENIX, the W boson produced in pp collision at center of mass energies of about 500 GeV is accessed via its decays into electron (muon) at central (forward) rapidities. Here the status of the analysis and the most updated results is reported.

  15. Fine structure in the transition region: reaction force analyses of water-assisted proton transfers.

    PubMed

    Yepes, Diana; Murray, Jane S; Santos, Juan C; Toro-Labbé, Alejandro; Politzer, Peter; Jaque, Pablo

    2013-07-01

    We have analyzed the variation of the reaction force F(ξ) and the reaction force constant κ(ξ) along the intrinsic reaction coordinates ξ of the water-assisted proton transfer reactions of HX-N = Y (X,Y = O,S). The profile of the force constant of the vibration associated with the reactive mode, k ξ (ξ), was also determined. We compare our results to the corresponding intramolecular proton transfers in the absence of a water molecule. The presence of water promotes the proton transfers, decreasing the energy barriers by about 12 - 15 kcal mol(-1). This is due in part to much smaller bond angle changes being needed than when water is absent. The κ(ξ) profiles along the intrinsic reaction coordinates for the water-assisted processes show striking and intriguing differences in the transition regions. For the HS-N = S and HO-N = S systems, two κ(ξ) minima are obtained, whereas for HO-N = O only one minimum is found. The k ξ (ξ) show similar behavior in the transition regions. We propose that this fine structure reflects the degree of synchronicity of the two proton migrations in each case. PMID:22733272

  16. Investigation of the structure of light exotic nuclei by proton elastic scattering in inverse kinematics

    SciTech Connect

    Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V. Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.

    2015-05-15

    In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the {sup 6}He, {sup 8}He, {sup 11}Li, and {sup 14}Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the {sup 8}Li, {sup 9}Li, and {sup 12}Be nuclei.

  17. Surface Protonation at the Rutile (110) Interface: Explicit Incorporation of Solvation Structure within the Refined MUSIC Model Framework

    SciTech Connect

    Machesky, Michael L.; Predota, M.; Wesolowski, David J

    2008-11-01

    The detailed solvation structure at the (110) surface of rutile ({alpha}-TiO{sub 2}) in contact with bulk liquid water has been obtained primarily from experimentally verified classical molecular dynamics (CMD) simulations of the ab initio-optimized surface in contact with SPC/E water. The results are used to explicitly quantify H-bonding interactions, which are then used within the refined MUSIC model framework to predict surface oxygen protonation constants. Quantum mechanical molecular dynamics (QMD) simulations in the presence of freely dissociable water molecules produced H-bond distributions around deprotonated surface oxygens very similar to those obtained by CMD with nondissociable SPC/E water, thereby confirming that the less computationally intensive CMD simulations provide accurate H-bond information. Utilizing this H-bond information within the refined MUSIC model, along with manually adjusted Ti-O surface bond lengths that are nonetheless within 0.05 {angstrom} of those obtained from static density functional theory (DFT) calculations and measured in X-ray reflectivity experiments (as well as bulk crystal values), give surface protonation constants that result in a calculated zero net proton charge pH value (pHznpc) at 25 C that agrees quantitatively with the experimentally determined value (5.4 {+-} 0.2) for a specific rutile powder dominated by the (110) crystal face. Moreover, the predicted pH{sub znpc} values agree to within 0.1 pH unit with those measured at all temperatures between 10 and 250 C. A slightly smaller manual adjustment of the DFT-derived Ti-O surface bond lengths was sufficient to bring the predicted pH{sub znpc} value of the rutile (110) surface at 25 C into quantitative agreement with the experimental value (4.8 {+-} 0.3) obtained from a polished and annealed rutile (110) single crystal surface in contact with dilute sodium nitrate solutions using second harmonic generation (SHG) intensity measurements as a function of ionic

  18. Surface protonation at the rutile (110) interface: explicit incorporation of solvation structure within the refined MUSIC model framework.

    PubMed

    Machesky, Michael L; Predota, Milan; Wesolowski, David J; Vlcek, Lukas; Cummings, Peter T; Rosenqvist, Jörgen; Ridley, Moira K; Kubicki, James D; Bandura, Andrei V; Kumar, Nitin; Sofo, Jorge O

    2008-11-01

    The detailed solvation structure at the (110) surface of rutile (alpha-TiO2) in contact with bulk liquid water has been obtained primarily from experimentally verified classical molecular dynamics (CMD) simulations of the ab initio-optimized surface in contact with SPC/E water. The results are used to explicitly quantify H-bonding interactions, which are then used within the refined MUSIC model framework to predict surface oxygen protonation constants. Quantum mechanical molecular dynamics (QMD) simulations in the presence of freely dissociable water molecules produced H-bond distributions around deprotonated surface oxygens very similar to those obtained by CMD with nondissociable SPC/E water, thereby confirming that the less computationally intensive CMD simulations provide accurate H-bond information. Utilizing this H-bond information within the refined MUSIC model, along with manually adjusted Ti-O surface bond lengths that are nonetheless within 0.05 A of those obtained from static density functional theory (DFT) calculations and measured in X-ray reflectivity experiments (as well as bulk crystal values), give surface protonation constants that result in a calculated zero net proton charge pH value (pHznpc) at 25 degrees C that agrees quantitatively with the experimentally determined value (5.4+/-0.2) for a specific rutile powder dominated by the (110) crystal face. Moreover, the predicted pHznpc values agree to within 0.1 pH unit with those measured at all temperatures between 10 and 250 degrees C. A slightly smaller manual adjustment of the DFT-derived Ti-O surface bond lengths was sufficient to bring the predicted pHznpcvalue of the rutile (110) surface at 25 degrees C into quantitative agreement with the experimental value (4.8+/-0.3) obtained from a polished and annealed rutile (110) single crystal surface in contact with dilute sodium nitrate solutions using second harmonic generation (SHG) intensity measurements as a function of ionic strength

  19. Design summary of the magnet support structures for the proton storage ring injection line upgrade

    SciTech Connect

    Bernardin, J.D.; Ledford, J.E.; Smith, B.G.

    1997-05-01

    This report summarizes the technical engineering and design issues associated with the Proton Storage Ring (PSR) Injection Line upgrade of the Los Alamos Neutron Science Center (LANSCE). The main focus is on the engineering design calculations of several magnet support structures. The general procedure based upon a set number of design criteria is outlined, followed by a case-by-case summary of the engineering design analyses, reutilization or fabrication callouts and design safety factors.

  20. Protonation of bridging sulfur in cubanoid Fe4S4 clusters causes large geometric changes: the theory of geometric and electronic structure.

    PubMed

    Dance, Ian

    2015-03-14

    Density functional calculations indicate that protonation of a μ3-S atom in cubanoid clusters [Fe4S4X4](2-) leads to a large extension of one Fe-S(H) bond such that the SH ligand is doubly-bridging, μ-SH. Triply-bridging SH in these clusters is unstable, relative to μ-SH. The theory for the geometric and electronic structures of the protonated [Fe4S4X4](2-) clusters (X = Cl, SEt, SMe, SPh, OMe, OPh) is presented in this paper. The principal results are (1) the unique Fe atom in [Fe4S3(SH)X4](-) is three-coordinate, with planar or approximately planar stereochemistry, (2) approximately equi-energetic endo and exo isomers occur for pyramidal μ-SH, (3) the structural changes caused by protonation reverse without barrier on deprotonation, (4) the most stable electronic states have S = 0 and oppositely signed spin densities on the Fe atoms bearing the μ-SH bridge, (5) interconversions between endo and exo isomers, and between ground and excited states, occur through concerted lengthenings and shortenings of Fe-S(H) interactions, on relatively flat energy surfaces, (6) protonation of an X ligand does not change the characteristics of protonation of μ3-S. Experimental tests of this theory are suggested, and applications discussed. PMID:25664573

  1. Molecular hydrogen messengers can lead to structural infidelity: A cautionary tale of protonated glycine

    NASA Astrophysics Data System (ADS)

    Masson, Antoine; Williams, Evan R.; Rizzo, Thomas R.

    2015-09-01

    The effects of tagging protonated glycine with either He or between 1 and 14 H2 molecules on the infrared photodissociation spectra and the ion structure were investigated. Differences in the IR spectra with either a single He atom or H2 molecule attached indicate that even a single H2 molecule can affect the frequencies of some vibrational bands of this simple ion. The protonation site is the preferred location of the tag with He and with up to two H2 molecules, but evidence for H2 attachment to the hydrogen atom of the uncharged carboxylic acid is observed for ions tagged with three or more H2 molecules. This results in a 55 cm-1 red shift in the carboxylic acid OH stretch, and evidence for some structural isomers where the hydrogen bond between the protonated nitrogen and the carbonyl oxygen is partially broken; as a result H2 molecules attached to this site are observed. These results are supported by theory, which indicates that H2 molecules can effectively break this weak hydrogen bond with three or more H2 molecules. These results indicate that large spectral shifts as a result of H2 molecules attaching to sites remote from the charge can occur and affect stretching frequencies as a result of charge transfer, and that tagging with multiple H2 molecules can change the structure of the ion itself.

  2. Disgust: Evolved Function and Structure

    ERIC Educational Resources Information Center

    Tybur, Joshua M.; Lieberman, Debra; Kurzban, Robert; DeScioli, Peter

    2013-01-01

    Interest in and research on disgust has surged over the past few decades. The field, however, still lacks a coherent theoretical framework for understanding the evolved function or functions of disgust. Here we present such a framework, emphasizing 2 levels of analysis: that of evolved function and that of information processing. Although there is…

  3. Structure and function of vanadium compounds in living organisms.

    PubMed

    Rehder, D

    1992-01-01

    Vanadium has been recognized as a metal of biological importance only recently. In this mini-review, its main functions uncovered during the past few years are addressed. These encompass (i) the regulation of phosphate metabolizing enzymes (which is exemplified for the inhibition of ribonucleases by vanadate), (ii) the halogenation of organic compounds by vanadate-dependent non-heme peroxidases from seaweeds, (iii) the reductive protonation of nitrogen (nitrogen fixation) by alternative, i.e. vanadium-containing, nitrogenases from N2-fixing bacteria, (iv) vanadium sequestering by sea squirts (ascidians), and (v) amavadine, a low molecular weight complex of V(IV) accumulated in the fly agaric and related toadstools. The function of vanadium, while still illusive in ascidians and toadstools, begins to be understood in vanadium-enzyme interaction. Investigations into the structure and function of model compounds play an increasingly important role in elucidating the biological significance of vanadium. PMID:1392470

  4. Characteristics of velocity distribution functions and entry mechanisms of protons in the near-lunar wake from SWIM/SARA on Chandrayaan-1

    NASA Astrophysics Data System (ADS)

    Dhanya, M. B.; Barabash, Stas; Wieser, Martin; Holmström, Mats; Bhardwaj, Anil; Wurz, Peter; Alok, Abhinaw; Futaana, Yoshifumi

    2016-07-01

    Moon is an airless body with no global magnetic field, although regions of crustal magnetic fields known as magnetic anomalies exist on Moon. Solar wind, the magnetized plasma flow from the Sun, continuously impinges on Moon. Due to the high absorption of solar wind plasma on the lunar dayside, a large scale wake structure is formed downstream of the Moon. However, recent in-situ observations have revealed the presence of protons in the near-lunar wake (100 km to 200 km from the surface). The source of these protons have been found to be the solar wind that enter the wake either directly or after interaction with the lunar surface or with the magnetic anomalies. Using the entire data from the SWIM sensor, which was an ion-mass analyzer, of the SARA experiment onboard Chandrayaan-1, the characteristics of velocity distribution of these protons were investigated to understand the entry mechanisms to near lunar wake. The velocity distribution functions were computed in the two dimensional velocity space, namely in the directions parallel and perpendicular to the IMF (v_allel and v_perp) in the solar wind rest frame. Several proton populations were identified from the velocity distribution and their possible entry mechanism were inferred based on the characteristics of the velocity distribution. These entry mechanisms include (i) diffusion of solar wind protons into the wake along IMF, (ii) the solar wind protons with finite gyro-radii that are aided by the wake boundary electric field, (iii) solar wind protons with gyro-radii larger than lunar radii from the tail of the solar wind velocity distribution, and (iv) scattering of solar wind protons from the dayside lunar surface or from magnetic anomalies. In order to gain more insight into the entry mechanisms associated with different populations, the trajectories of the protons were computed backward in time (backtracing) for each of these populations. For most of the populations, the source mechanism obtained from

  5. Functional keratin as structural platforms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wool with up to 95% keratin by weight is a rich and pure source of proteinous biomaterial. As polymeric polyamide it exhibits high functionality through amide, carboxyl, sulfoxide, sulfide, and thiosulfide functions. Solubilized wool was transformed into keratin morphologies with the unique characte...

  6. Stories: The Function of Structure.

    ERIC Educational Resources Information Center

    Mandler, Jean M.

    The differences between story grammar and story schema are outlined and discussed based on research on story understanding by children and adults. The contention of all story grammars is that stories have a relatively invariant structure despite great differences in story content. The importance of structure within folk tales, and the ways in…

  7. Spherical proton-neutron structure of isomeric states in {sup 128}Cd

    SciTech Connect

    Caceres, L.; Gorska, M.; Grawe, H.; Sieja, K.; Geissel, H.; Gerl, J.; Kojouharov, I.; Kurz, N.; Montes, F.; Martinez-Pinedo, G.; Prokopowicz, W.; Schaffner, H.; Tashenov, S.; Wollersheim, H. J.; Jungclaus, A.; Pfuetzner, M.; Werner-Malento, E.; Nowacki, F.

    2009-01-15

    The {gamma}-ray decay of isomeric states in the even-even nucleus {sup 128}Cd has been observed. The nucleus of interest was produced both by the fragmentation of {sup 136}Xe and the fission of {sup 238}U primary beams. The level scheme was unambiguously constructed based on {gamma}{gamma} coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the N=82 shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to {pi}{nu} interaction in overlapping orbitals for both proton and neutron holes.

  8. Study of the proton structure by measurements of polarization transfers in real Compton scattering at Jlab

    SciTech Connect

    Fanelli, Cristiano Fanelli; Cisbani, Evarostp; Hamilton, David; Salme, G.; Wojtsekhowski, Bogdan B.

    2014-03-01

    A preliminary analysis of polarization-transfer data at large scattering angle (70°), obtained in an experiment of real Compton scattering on proton, performed in Hall-C of Jefferson Lab, is presented. It is also discussed the relevance of this kind of experiments for shedding light on the non-perturbative structure of the proton, at low energy, and on the transition from the non-perturbative regime to the perturbative one, that occurs at high energy. Moreover, the possibility to extract Compton form factors and the Generalized Parton Distributions, one of the most promising theoretical tool to determine the total angular momentum contribution of quarks and gluons to nucleon spin, is emphasized.

  9. Identification of excited structures in proton unbound nuclei 173,175,177Au: shape co-existence and intruder bands

    NASA Astrophysics Data System (ADS)

    Kondev, F. G.; Carpenter, M. P.; Janssens, R. V. F.; Abu Saleem, K.; Ahmad, I.; Amro, H.; Cizewski, J. A.; Danchev, M.; Davids, C. N.; Hartley, D. J.; Heinz, A.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Ma, W. C.; Poli, G. L.; Ressler, J.; Reviol, W.; Riedinger, L. L.; Seweryniak, D.; Smith, M. B.; Wiedenhöver, I.

    2001-07-01

    Excited states in the proton-unbound 173,175,177Au nuclei were identified for the first time. Level structures associated with three different shapes were observed in 175Au. While the yrast lines of 175Au and 177Au consist of a prolate band built upon the intruder 1/2+[660] (i13/2) proton orbital, no sign of collectivity was observed in the lighter 173Au isotope. Implications for the deformation associated with these structures are discussed with a focus on shape co-existence in the vicinity of the proton-drip line.

  10. From the HINDAS Project: Excitation Functions for Residual Nuclide Production by Proton-Induced Reactions

    SciTech Connect

    Michel, R.; Gloris, M.; Protoschill, J.; Uosif, M.A.M.; Weug, M.; Herpers, U.; Kuhnhenn, J.; Kubik, P.-W.; Schumann, D.; Synal, H.-A.; Weinreich, R.; Leya, I.; David, J.C.; Leray, S.; Duijvestijn, M.; Koning, A.; Kelic, A.; Schmidt, K.H.; Cugnon, J.

    2005-05-24

    A survey is given about efforts undertaken during the HINDAS project to investigate the energy dependence of residual nuclide production by proton-induced reactions from thresholds up to 2.6 GeV. For proton-induced reactions, our experiments aimed to further develop and complete the cross-section database that was established by our collaboration in recent years. It was extended to the heavy-target elements Ta, W, Pb, and Bi for energies up to 2.6 GeV. In addition, new measurements for the target element iron were performed up to 2.6 GeV and for natural uranium for energies from 21 MeV to 69 MeV. For the target element lead, a comprehensive set of excitation functions published recently was completed by AMS-measurements of cross sections for the production of the long-lived radionuclides Be-10, Al-26, Cl-36, and I-129 and by mass spectrometric measurements for stable and radioactive rare gas isotopes of He, Ne, Ar, Kr, and Xe. Comprehensive tests of the nuclear-reaction codes TALYS and INCL4+ABLA, which were developed within the HINDAS project, were performed with the new experimental results over the entire energy range.

  11. Estolides: From Structure and Function to Structured and Functionalized

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oligomeric fatty acid esters, known as estolides, have been studied for close to a century. It has only been in the last dozen or so years, however, that efficient methods for preparing estolides have been developed that also allow for a modicum of control over their molecular structures. By varyi...

  12. Quantum effect on the internal proton transfer and structural fluctuation in the H+ 5 cluster.

    PubMed

    Ohta, Yasuhito; Ohta, Koji; Kinugawa, Kenichi

    2004-12-01

    The thermal equilibrium state of H+(5) is investigated by means of an ab initio path integral molecular dynamics (PIMD) method, in which degrees of freedom of both nuclei and electrons at finite temperature are quantized within the adiabatic approximation. The second-order Moller-Plesset force field has been employed for the present ab initio PIMD. At 5-200 K, H+(5) is shown to have the structure that the proton is surrounded by the two H(2) units without any exchange of an atom between the central proton and the H(2) unit. At 5 K, the quantum tunneling of the central proton occurs more easily when the distance between the two H(2) units is shortened. At the high temperature of 200 K, the central proton is more delocalized in space between the two H(2) units, with less correlation with the stretching of the distance between the two H(2) units. As for the rotation of the H(2) units around the C(2) axis of H+(5) , the dihedral angle distribution is homogeneous at all temperatures, suggesting that the two H(2) units freely rotate around the C(2) axis, while this quantum effect on the rotation of the H(2) units becomes more weakened with increasing temperature. The influence of the structural fluctuation of H+(5) on molecular orbital energies has been examined to conclude that the highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap is largely reduced with the increase of temperature because of the spatial expansion of the whole cluster. PMID:15634048

  13. Proton and deuteron induced reactions on natGa: Experimental and calculated excitation functions

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Adam-Rebeles, R.; Tárkányi, F.; Takács, S.; Ditrói, F.

    2015-09-01

    Cross-sections for reactions on natGa, induced by protons (up to 65 MeV) and deuterons (up to 50 MeV), producing γ-emitting radionuclides with half-lives longer than 1 h were measured in a stacked-foil irradiation using thin Ga-Ni alloy (70-30%) targets electroplated on Cu or Au backings. Excitation functions for generation of 68,69Ge, 66,67,68,72Ga and 65,69mZn on natGa are discussed, relative to the monitor reactions natAl(d,x)24,22Na, natAl(p,x)24,22Na, natCu(p,x)62Zn and natNi(p,x)57Ni. The results are compared to our earlier measurements, the scarce literature values and to the results of the code TALYS 1.6 (online database TENDL-2014).

  14. From structure to function, via dynamics

    NASA Astrophysics Data System (ADS)

    Stetter, O.; Soriano, J.; Geisel, T.; Battaglia, D.

    2013-01-01

    Neurons in the brain are wired into a synaptic network that spans multiple scales, from local circuits within cortical columns to fiber tracts interconnecting distant areas. However, brain function require the dynamic control of inter-circuit interactions on time-scales faster than synaptic changes. In particular, strength and direction of causal influences between neural populations (described by the so-called directed functional connectivity) must be reconfigurable even when the underlying structural connectivity is fixed. Such directed functional influences can be quantified resorting to causal analysis of time-series based on tools like Granger Causality or Transfer Entropy. The ability to quickly reorganize inter-areal interactions is a chief requirement for performance in a changing natural environment. But how can manifold functional networks stem "on demand" from an essentially fixed structure? We explore the hypothesis that the self-organization of neuronal synchronous activity underlies the control of brain functional connectivity. Based on simulated and real recordings of critical neuronal cultures in vitro, as well as on mean-field and spiking network models of interacting brain areas, we have found that "function follows dynamics", rather than structure. Different dynamic states of a same structural network, characterized by different synchronization properties, are indeed associated to different functional digraphs (functional multiplicity). We also highlight the crucial role of dynamics in establishing a structure-to-function link, by showing that whenever different structural topologies lead to similar dynamical states, than the associated functional connectivities are also very similar (structural degeneracy).

  15. New tetracobalt cluster compounds for electrocatalytic proton reduction: syntheses, structures, and reactivity.

    PubMed

    Li, Ping; Zaffaroni, Riccardo; de Bruin, Bas; Reek, Joost N H

    2015-03-01

    Reaction of Co2(CO)8 and 1,3-propanedithiol in a 1:1 molar ratio in toluene affords a novel tetracobalt complex, [(μ2-pdt)2(μ3-S)Co4(CO)6] (pdt = -SCH2CH2CH2S-, 1), which possesses some of the structural features of the active site of [FeFe]-hydrogenase. Carbonyl displacement reaction of complex 1 in the presence of mono- or diphosphine ligands leads to the formation of [(μ2-pdt)2(μ3-S)Co4(CO)5(PCy3)] (2) and [(μ2-pdt)2(μ3-S)Co4(CO)4(L)] [L = Ph2PCH=CHPPh2, 3; Ph2PCH2N(Ph)CH2PPh2, 4; Ph2PCH2N(iPr)CH2PPh2, 5]. Complexes 1-5 have been fully characterized by spectroscopy and single-crystal X-ray diffraction studies. Cyclic voltammetry has revealed that complexes 1-5 show a reversible first reduction wave and are active for electrocatalytic proton reduction in the presence of CF3COOH. Protonation reactions have been monitored by (31)P and (1)H NMR and infrared spectroscopies, which revealed the formation of different protonated species. The mono-reduced species of 1-5 have been spectroscopically characterized by EPR and spectro-electro-infrared techniques. PMID:25639914

  16. Structure-Independent Proton Transport in Cerium(III) Phosphate Nanowires.

    PubMed

    Pusztai, Péter; Haspel, Henrik; Tóth, Ildikó Y; Tombácz, Etelka; László, Krisztina; Kukovecz, Ákos; Kónya, Zoltán

    2015-05-13

    Understanding of water-related electrical conduction is of utmost importance in applications that utilize solid-state proton conductors. However, in spite of the vast amount of theoretical and experimental work published in the literature, thus far its mechanism remained unsolved. In this study, the structure-related ambient temperature electrical conduction of one-dimensional hydrophilic nanostructures was investigated. Cerium phosphate nanowires with monoclinic and hexagonal crystal structures were synthesized via the hydrothermal and ambient temperature precipitation routes, and their structural and surface properties were examined by using high-resolution transmission electron microscopy, X-ray diffractometry, nitrogen and water sorption, temperature-programmed ammonia desorption, and potentiometric titration techniques. The relative humidity (RH)-dependent charge-transport processes of hexagonal and monoclinic nanowires were investigated by means of impedance spectroscopy and transient ionic current measurement techniques to gain insight into their atomistic level mechanism. Although considerable differences in RH-dependent conductivity were first found, the distinct characteristics collapsed into a master curve when specific surface area and acidity were taken into account, implying structure-independent proton conduction mechanism in both types of nanowires. PMID:25859883

  17. Structures of intermediate transport states of ZneA, a Zn(II)/proton antiporter.

    PubMed

    Pak, John Edward; Ekendé, Elisabeth Ngonlong; Kifle, Efrem G; O'Connell, Joseph Daniel; De Angelis, Fabien; Tessema, Meseret B; Derfoufi, Kheiro-Mouna; Robles-Colmenares, Yaneth; Robbins, Rebecca A; Goormaghtigh, Erik; Vandenbussche, Guy; Stroud, Robert M

    2013-11-12

    Efflux pumps belonging to the ubiquitous resistance-nodulation-cell division (RND) superfamily transport substrates out of cells by coupling proton conduction across the membrane to a conformationally driven pumping cycle. The heavy metal-resistant bacteria Cupriavidus metallidurans CH34 relies notably on as many as 12 heavy metal efflux pumps of the RND superfamily. Here we show that C. metallidurans CH34 ZneA is a proton driven efflux pump specific for Zn(II), and that transport of substrates through the transmembrane domain may be electrogenic. We report two X-ray crystal structures of ZneA in intermediate transport conformations, at 3.0 and 3.7 Å resolution. The trimeric ZneA structures capture protomer conformations that differ in the spatial arrangement and Zn(II) occupancies at a proximal and a distal substrate binding site. Structural comparison shows that transport of substrates through a tunnel that links the two binding sites, toward an exit portal, is mediated by the conformation of a short 14-aa loop. Taken together, the ZneA structures presented here provide mechanistic insights into the conformational changes required for substrate efflux by RND superfamily transporters. PMID:24173033

  18. Fabrication of sulfonated poly(ether ether ketone)-based hybrid proton-conducting membranes containing carboxyl or amino acid-functionalized titania by in situ sol-gel process

    NASA Astrophysics Data System (ADS)

    Yin, Yongheng; Xu, Tao; He, Guangwei; Jiang, Zhongyi; Wu, Hong

    2015-02-01

    Functionalized titania are used as fillers to modify the sulfonated poly(ether ether ketone) (SPEEK) membrane for improved proton conductivity and methanol barrier property. The functionalized titania sol which contains proton conductive carboxylic acid groups or amino acid groups are derived from a facile chelation method using different functional additives. Then the novel SPEEK/carboxylic acid-functionalized titania (SPEEK/TC) and SPEEK/amino acid-functionalized titania (SPEEK/TNC) hybrid membranes are fabricated via in situ sol-gel method. The anti-swelling property and thermal stability of hybrid membranes are enhanced owing to the formation of electrostatic force between SPEEK and titania nanoparticles. The hybrid membranes exhibit higher proton conductivity than plain SPEEK membrane because more proton transfer sites are provided by the functionalized titania nanoparticles. Particularly, the proton conductivity of SPEEK/TNC membrane with 15% filler content reaches up to 6.24 × 10-2 S cm-1, which is 3.5 times higher than that of the pure SPEEK membrane. For methanol permeability, the SPEEK/TNC membranes possess the lowest values because the acid-base interaction between sulfonic acid groups in SPEEK and amino groups in functionalized titania leads to a more compact membrane structure.

  19. Response functions of Fuji imaging plates to monoenergetic protons in the energy range 0.6-3.2 MeV

    SciTech Connect

    Bonnet, T.; Denis-Petit, D.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Aleonard, M. M.

    2013-01-15

    We have measured the responses of Fuji MS, SR, and TR imaging plates (IPs) to protons with energies ranging from 0.6 to 3.2 MeV. Monoenergetic protons were produced with the 3.5 MV AIFIRA (Applications Interdisciplinaires de Faisceaux d'Ions en Region Aquitaine) accelerator at the Centre d'Etudes Nucleaires de Bordeaux Gradignan (CENBG). The IPs were irradiated with protons backscattered off a tantalum target. We present the photo-stimulated luminescence response of the IPs together with the fading measurements for these IPs. A method is applied to allow correction of fading effects for variable proton irradiation duration. Using the IP fading corrections, a model of the IP response function to protons was developed. The model enables extrapolation of the IP response to protons up to proton energies of 10 MeV. Our work is finally compared to previous works conducted on Fuji TR IP response to protons.

  20. X-ray-induced catalytic active-site reduction of a multicopper oxidase: structural insights into the proton-relay mechanism and O2-reduction states.

    PubMed

    Serrano-Posada, Hugo; Centeno-Leija, Sara; Rojas-Trejo, Sonia Patricia; Rodríguez-Almazán, Claudia; Stojanoff, Vivian; Rudiño-Piñera, Enrique

    2015-12-01

    During X-ray data collection from a multicopper oxidase (MCO) crystal, electrons and protons are mainly released into the system by the radiolysis of water molecules, leading to the X-ray-induced reduction of O2 to 2H2O at the trinuclear copper cluster (TNC) of the enzyme. In this work, 12 crystallographic structures of Thermus thermophilus HB27 multicopper oxidase (Tth-MCO) in holo, apo and Hg-bound forms and with different X-ray absorbed doses have been determined. In holo Tth-MCO structures with four Cu atoms, the proton-donor residue Glu451 involved in O2 reduction was found in a double conformation: Glu451a (∼7 Å from the TNC) and Glu451b (∼4.5 Å from the TNC). A positive peak of electron density above 3.5σ in an Fo - Fc map for Glu451a O(ℇ2) indicates the presence of a carboxyl functional group at the side chain, while its significant absence in Glu451b strongly suggests a carboxylate functional group. In contrast, for apo Tth-MCO and in Hg-bound structures neither the positive peak nor double conformations were observed. Together, these observations provide the first structural evidence for a proton-relay mechanism in the MCO family and also support previous studies indicating that Asp106 does not provide protons for this mechanism. In addition, eight composite structures (Tth-MCO-C1-8) with different X-ray-absorbed doses allowed the observation of different O2-reduction states, and a total depletion of T2Cu at doses higher than 0.2 MGy showed the high susceptibility of this Cu atom to radiation damage, highlighting the importance of taking radiation effects into account in biochemical interpretations of an MCO structure. PMID:26627648

  1. Structure and Function in Soil Hydrology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Structure of soil and soil cover is the major control of soil hydrologic functioning, being in turn controlled with multiple feedbacks. Existing methods and parameters to characterize both soil/soil cover structure and soil hydrologic functioning are scale-dependent. The purpose of this presentation...

  2. Correlation Functions and Glass Structure

    NASA Astrophysics Data System (ADS)

    Chergui, Y.; Nehaoua, N.; Telghemti, B.; Guemid, S.; Deraddji, N. E.; Belkhir, H.; Mekki, D. E.

    2011-04-01

    This work presents the use of molecular dynamics (MD) and the code of Dl Poly, in order to study the structure of fluoride glass after melting and quenching. We are realized the processing phase liquid-phase, simulating rapid quenching at different speeds to see the effect of quenching rate on the operation of the devitrification. This technique of simulation has become a powerful tool for investigating the microscopic behaviour of matter as well as for calculating macroscopic observable quantities. As basic results, we calculated the interatomic distance, angles and statistics, which help us to know the geometric form and the structure of PbF2. These results are in experimental agreement to those reported in literature.

  3. Molecular hydrogen messengers can lead to structural infidelity: A cautionary tale of protonated glycine

    SciTech Connect

    Masson, Antoine Rizzo, Thomas R. E-mail: thomas.rizzo@epfl.ch; Williams, Evan R. E-mail: thomas.rizzo@epfl.ch

    2015-09-14

    The effects of tagging protonated glycine with either He or between 1 and 14 H{sub 2} molecules on the infrared photodissociation spectra and the ion structure were investigated. Differences in the IR spectra with either a single He atom or H{sub 2} molecule attached indicate that even a single H{sub 2} molecule can affect the frequencies of some vibrational bands of this simple ion. The protonation site is the preferred location of the tag with He and with up to two H{sub 2} molecules, but evidence for H{sub 2} attachment to the hydrogen atom of the uncharged carboxylic acid is observed for ions tagged with three or more H{sub 2} molecules. This results in a 55 cm{sup −1} red shift in the carboxylic acid OH stretch, and evidence for some structural isomers where the hydrogen bond between the protonated nitrogen and the carbonyl oxygen is partially broken; as a result H{sub 2} molecules attached to this site are observed. These results are supported by theory, which indicates that H{sub 2} molecules can effectively break this weak hydrogen bond with three or more H{sub 2} molecules. These results indicate that large spectral shifts as a result of H{sub 2} molecules attaching to sites remote from the charge can occur and affect stretching frequencies as a result of charge transfer, and that tagging with multiple H{sub 2} molecules can change the structure of the ion itself.

  4. Structure-function investigations of bacterial photosynthetic reaction centers.

    PubMed

    Leonova, M M; Fufina, T Yu; Vasilieva, L G; Shuvalov, V A

    2011-12-01

    During photosynthesis light energy is converted into energy of chemical bonds through a series of electron and proton transfer reactions. Over the first ultrafast steps of photosynthesis that take place in the reaction center (RC) the quantum efficiency of the light energy transduction is nearly 100%. Compared to the plant and cyanobacterial photosystems, bacterial RCs are well studied and have relatively simple structure. Therefore they represent a useful model system both for manipulating of the electron transfer parameters to study detailed mechanisms of its separate steps as well as to investigate the common principles of the photosynthetic RC structure, function, and evolution. This review is focused on the research papers devoted to chemical and genetic modifications of the RCs of purple bacteria in order to study principles and mechanisms of their functioning. Investigations of the last two decades show that the maximal rates of the electron transfer reactions in the RC depend on a number of parameters. Chemical structure of the cofactors, distances between them, their relative orientation, and interactions to each other are of great importance for this process. By means of genetic and spectral methods, it was demonstrated that RC protein is also an essential factor affecting the efficiency of the photochemical charge separation. Finally, some of conservative water molecules found in RC not only contribute to stability of the protein structure, but are directly involved in the functioning of the complex. PMID:22339599

  5. The structure and function of catalytic RNAs.

    PubMed

    Wu, QiJia; Huang, Lin; Zhang, Yi

    2009-03-01

    Before the discovery of ribozymes, RNA had been proposed to function as a catalyst, based on the discovery that RNA folded into high-ordered structures as protein did. This hypothesis was confirmed in the 1980s, after the discovery of Tetrahymena group I intron and RNase P ribozyme. There have been about ten ribozymes identified during the past thirty years, as well as the fact that ribosomes function as ribozymes. Advances have been made in understanding the structures and functions of ribozymes, with numerous crystal structures resolved in the past years. Here we review the structure-function relationship of both small and large ribozymes, especially the structural basis of their catalysis. ribozyme, structure, catalysis. PMID:19294348

  6. Nanohydration of uracil: emergence of three-dimensional structures and proton-induced charge transfer.

    PubMed

    Bacchus-Montabonel, Marie-Christine; Calvo, Florent

    2015-04-21

    Stepwise hydration of uracil has been theoretically revisited using different methods ranging from classical force fields to quantum chemical approaches. Hydration initially begins within the uracil plane but proceeds at four molecules into three-dimensional configurations or even water clusters next to the nucleobase. The relative stability between the various structures is significantly affected by zero-point energy and finite temperature (entropy) effects and also gives rise to markedly different responses to an excitation by an impinging high-energy proton. In particular, charge transfer to the molecular complex is dramatically altered in collisions toward the coating cluster but barely modified for peripheral hydration patterns. PMID:25793649

  7. Structure of proton centers and associated nonthermal bursts at microwave frequencies

    NASA Technical Reports Server (NTRS)

    Enome, S.; Tanaka, H.

    1973-01-01

    A very broad band of electromagnetic radiation is emitted during solar flares, especially at the explosive phase. The existence of a large variety of plasmas with various densities and a wide range of temperatures or energies is proposed as the initiating agent. The manner in which the plasmas are heated and accelerated to subrelativistic and relativistic energies is discussed. Observational evidence on the characteristics of active regions which produced proton flares and on the structure of the associated nonthermal microwave bursts of the sun is presented. The behavior of subrelativistic electrons on the sun is described.

  8. Medium-spin structure of single valence-proton nucleus {sup 133}Sb

    SciTech Connect

    Urban, W.; Kurcewicz, W.; Korgul, A.; Daly, P. J.; Bhattacharyya, P.; Zhang, C. T.; Durell, J. L.; Leddy, M. J.; Jones, M. A.; Phillips, W. R.

    2000-08-01

    Excited states in the nucleus {sup 133}Sb, populated in spontaneous fission of {sup 248}Cm, were studied with EUROGAM2. Medium-spin structure, described as the {nu}(f{sub 7/2}h{sub 11/2}{sup -1}) multiplet of the {sup 132}Sn core coupled to the odd proton in the g{sub 7/2} orbital, has been identified in this nucleus. Levels corresponding to the octupole excitations of the {sup 132}Sn core were also identified. Some uncertainties concerning isomeric decays in {sup 133}Sb, observed in previous works, have been resolved. (c) 2000 The American Physical Society.

  9. Weak-coupling structure of proton resonant states in 23Al studied with RI beam at CNS

    NASA Astrophysics Data System (ADS)

    He, J. J.; Kubono, S.; Teranishi, T.; Notani, M.; Michimasa, S.; Baba, H.; Nishimura, S.; Nishimura, M.; Yanagisawa, Y.; Hokoiwa, N.; Kibe, M.; Gono, Y.; Moon, J. Y.; Lee, J. H.; Lee, C. S.; Iwasaki, H.; Kato, S.

    2006-07-01

    Proton resonances in 23Al have been investigated for the first time by the resonant elastic and inelastic scattering of 22Mg+p by using a 4.38 MeV/nucleon 22Mg beam bombarding a thick Hydrogen target. The low-energy 22Mg beam was separated by the CNS radioactive ion beam separator (CRIB). A new resonant state due to elastic scattering was observed at Ex = 3.00 MeV with a Jπ = (3/2+) assignment. Other three excited states due to resonant inelastic scattering at 3.14, 3.26 and 3.95 MeV were identified and all mainly decay to the first excited state in 22Mg by the proton emissions. The newly observed 3.95-MeV state probably has a spin-parity of Jπ = (7/2+). The resonant properties were determined from an R-matrix analysis of the excitation functions. The weak-coupling structure in 23Al is discussed in conjunction with a shell-model calculation.

  10. Study of proton resonance structure in 27P via resonant elastic scattering of 26Si+p

    NASA Astrophysics Data System (ADS)

    Jung, H. S.; Lee, C. S.; Kwon, Y. K.; Moon, J. Y.; Lee, J. H.; Yun, C. C.; Kubono, S.; Yamaguchi, H.; Hashimoto, T.; Kahl, D.; Hayakawa, S.; Choi, Seonho; Kim, M. J.; Kim, Y. H.; Kim, Y. K.; Park, J. S.; Kim, E. J.; Moon, C.-B.; Teranishi, T.; Wakabayashi, Y.; Iwasa, N.; Yamada, T.; Togano, Y.; Kato, S.; Cherubini, S.; Rapisarda, G. G.

    2012-11-01

    A measurement of resonant elastic scattering of 26Si+p was performed with a thick target using a 26Si radioactive ion beam at the CRIB (CNS Radioactive Ion Beam separator) of the Center for Nuclear Study (CNS), the University of Tokyo. The excitation function of 27P was measured successfully with the inverse kinematics method through a covered the range of excitation energies from Ex ~ 2.3 to 3.8 MeV, providing information about the resonance structure of this nucleus. The properties of these resonances are important to better determine the production rates of 26Si(p,g)27P reaction, which is one of the astrophysically important nuclear reactions to understand the production of the 26Al. Some new resonant states have been investigated, and determined their resonance parameters, such as excitation energies, proton partial widths, and spin-parities by R-matrix calculation.