Measurement of diffraction dissociation cross sections in pp collisions at $$\\sqrt{s}$$ = 7 TeV

DOE PAGES

Khachatryan, Vardan

2015-07-06

Measurements of diffractive dissociation cross sections in pp collisions at √s=7 TeV are presented in kinematic regions defined by the masses M X and M Y of the two final-state hadronic systems separated by the largest rapidity gap in the event. The differential cross sections are measured as a function of ξ X = M2 X /s in the region -5.5 < log 10ξ X < -2.5, for log 10M Y < 0.5, dominated by single dissociation (SD), and 0.5 < log10M Y < 1.1, dominated by double dissociation (DD), where M X and M Y are given in GeV.more » The inclusive pp cross section is also measured as a function of the width of the central pseudorapidity gap Δη for Δη > 3, log 10 M X > 1.1, and log 10M Y > 1.1, a region dominated by DD. The cross sections integrated over these regions are found to be, respectively, 2.99 ± 0.02(stat) +0.32 -0.29(syst) mb, 1.18 ± 0.02(stat) ± 0.13(syst) mb, and 0.58 ± 0.01(stat) +0.13 -0.11(syst) mb, and are used to extract extrapolated total SD and DD cross sections. In addition, the inclusive differential cross section, dσ/dΔη F, for events with a pseudorapidity gap adjacent to the edge of the detector, is measured over Δη F = 8.4 units of pseudorapidity. The results are compared to those of other experiments and to theoretical predictions and found compatible with slowly rising diffractive cross sections as a function of center-of-mass energy.« less

Measurement of diffractive dissociation cross sections in p p collisions at √{s }=7 TeV

NASA Astrophysics Data System (ADS)

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Krätschmer, I.; Liko, D.; Mikulec, I.; Rabady, D.; Rahbaran, B.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Bansal, M.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Knutsson, A.; Luyckx, S.; Ochesanu, S.; Rougny, R.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Daci, N.; Heracleous, N.; Keaveney, J.; Lowette, S.; Maes, M.; Olbrechts, A.; Python, Q.; Strom, D.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Dobur, D.; Favart, L.; Gay, A. P. R.; Grebenyuk, A.; Léonard, A.; Mohammadi, A.; Perniè, L.; Reis, T.; Seva, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Zenoni, F.; Adler, V.; Beernaert, K.; Benucci, L.; Cimmino, A.; Costantini, S.; Crucy, S.; Dildick, S.; Fagot, A.; Garcia, G.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Salva Diblen, S.; Sigamani, M.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Beluffi, C.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; Da Silveira, G. G.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Nuttens, C.; Pagano, D.; Perrini, L.; Pin, A.; Piotrzkowski, K.; Popov, A.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Aldá Júnior, W. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Dos Reis Martins, T.; Mora Herrera, C.; Pol, M. E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Malbouisson, H.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santaolalla, J.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Aleksandrov, A.; Genchev, V.; Iaydjiev, P.; Marinov, A.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Hadjiiska, R.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Du, R.; Jiang, C. H.; Plestina, R.; Tao, J.; Wang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Zou, W.; Avila, C.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; Gomez Moreno, B.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Kadija, K.; Luetic, J.; Mekterovic, D.; Sudic, L.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Bodlak, M.; Finger, M.; Finger, M.; Assran, Y.; Ellithi Kamel, A.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Murumaa, M.; Raidal, M.; Tiko, A.; Eerola, P.; Fedi, G.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Baffioni, S.; Beaudette, F.; Busson, P.; Charlot, C.; Dahms, T.; Dalchenko, M.; Dobrzynski, L.; Filipovic, N.; Florent, A.; Granier de Cassagnac, R.; Mastrolorenzo, L.; Miné, P.; Mironov, C.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Paganini, P.; Regnard, S.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Veelken, C.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Chabert, E. C.; Collard, C.; Conte, E.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Goetzmann, C.; Le Bihan, A.-C.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Beaupere, N.; Boudoul, G.; Bouvier, E.; Brochet, S.; Carrillo Montoya, C. A.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Ruiz Alvarez, J. 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J.; Bergholz, M.; Bethani, A.; Borras, K.; Burgmeier, A.; Cakir, A.; Calligaris, L.; Campbell, A.; Choudhury, S.; Costanza, F.; Diez Pardos, C.; Dooling, S.; Dorland, T.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Flucke, G.; Garay Garcia, J.; Geiser, A.; Gunnellini, P.; Hauk, J.; Hempel, M.; Horton, D.; Jung, H.; Kalogeropoulos, A.; Kasemann, M.; Katsas, P.; Kieseler, J.; Kleinwort, C.; Krücker, D.; Lange, W.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Lutz, B.; Mankel, R.; Marfin, I.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Nayak, A.; Novgorodova, O.; Ntomari, E.; Perrey, H.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Ribeiro Cipriano, P. M.; Roland, B.; Ron, E.; Sahin, M. Ö.; Salfeld-Nebgen, J.; Saxena, P.; Schmidt, R.; Schoerner-Sadenius, T.; Schröder, M.; Seitz, C.; Spannagel, S.; Vargas Trevino, A. D. R.; Walsh, R.; Wissing, C.; Aldaya Martin, M.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Erfle, J.; Garutti, E.; Goebel, K.; Görner, M.; Haller, J.; Hoffmann, M.; Höing, R. S.; Kirschenmann, H.; Klanner, R.; Kogler, R.; Lange, J.; Lapsien, T.; Lenz, T.; Marchesini, I.; Ott, J.; Peiffer, T.; Pietsch, N.; Poehlsen, J.; Poehlsen, T.; Rathjens, D.; Sander, C.; Schettler, H.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Seidel, M.; Sola, V.; Stadie, H.; Steinbrück, G.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Barth, C.; Baus, C.; Berger, J.; Böser, C.; Butz, E.; Chwalek, T.; De Boer, W.; Descroix, A.; Dierlamm, A.; Feindt, M.; Frensch, F.; Giffels, M.; Hartmann, F.; Hauth, T.; Husemann, U.; Katkov, I.; Kornmayer, A.; Kuznetsova, E.; Lobelle Pardo, P.; Mozer, M. U.; Müller, Th.; Nürnberg, A.; Quast, G.; Rabbertz, K.; Ratnikov, F.; Röcker, S.; Simonis, H. J.; Stober, F. M.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weiler, T.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Markou, A.; Markou, C.; Psallidas, A.; Topsis-Giotis, I.; Agapitos, A.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Stiliaris, E.; Aslanoglou, X.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Bencze, G.; Hajdu, C.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Molnar, J.; Palinkas, J.; Szillasi, Z.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Swain, S. K.; Beri, S. B.; Bhatnagar, V.; Gupta, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, M.; Kumar, R.; Mittal, M.; Nishu, N.; Singh, J. B.; Kumar, Ashok; Kumar, Arun; Ahuja, S.; Bhardwaj, A.; Choudhary, B. C.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, V.; Banerjee, S.; Bhattacharya, S.; Chatterjee, K.; Dutta, S.; Gomber, B.; Jain, Sa.; Jain, Sh.; Khurana, R.; Modak, A.; Mukherjee, S.; Roy, D.; Sarkar, S.; Sharan, M.; Abdulsalam, A.; Dutta, D.; Kailas, S.; Kumar, V.; Mohanty, A. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Banerjee, S.; Bhowmik, S.; Chatterjee, R. M.; Dewanjee, R. K.; Dugad, S.; Ganguly, S.; Ghosh, S.; Guchait, M.; Gurtu, A.; Kole, G.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Mohanty, G. B.; Parida, B.; Sudhakar, K.; Wickramage, N.; Bakhshiansohi, H.; Behnamian, H.; Etesami, S. M.; Fahim, A.; Goldouzian, R.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Barbone, L.; Calabria, C.; Chhibra, S. S.; Colaleo, A.; Creanza, D.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Selvaggi, G.; Silvestris, L.; Singh, G.; Venditti, R.; Zito, G.; Abbiendi, G.; Benvenuti, A. C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Primavera, F.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Travaglini, R.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Gallo, E.; Gonzi, S.; Gori, V.; Lenzi, P.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Tropiano, A.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Ferretti, R.; Ferro, F.; Lo Vetere, M.; Robutti, E.; Tosi, S.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Gerosa, R.; Ghezzi, A.; Govoni, P.; Lucchini, M. T.; Malvezzi, S.; Manzoni, R. A.; Martelli, A.; Marzocchi, B.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Ragazzi, S.; Redaelli, N.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; Di Guida, S.; Fabozzi, F.; Iorio, A. O. M.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Azzi, P.; Bacchetta, N.; Bisello, D.; Branca, A.; Dall'Osso, M.; Dorigo, T.; Galanti, M.; Gasparini, F.; Giubilato, P.; Gozzelino, A.; Kanishchev, K.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. 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G.; Vernieri, C.; Barone, L.; Cavallari, F.; D'imperio, G.; Del Re, D.; Diemoz, M.; Grassi, M.; Jorda, C.; Longo, E.; Margaroli, F.; Meridiani, P.; Micheli, F.; Nourbakhsh, S.; Organtini, G.; Paramatti, R.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Soffi, L.; Traczyk, P.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bellan, R.; Biino, C.; Cartiglia, N.; Casasso, S.; Costa, M.; Degano, A.; Demaria, N.; Finco, L.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Musich, M.; Obertino, M. M.; Ortona, G.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Potenza, A.; Romero, A.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Tamponi, U.; Belforte, S.; Candelise, V.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Gobbo, B.; La Licata, C.; Marone, M.; Schizzi, A.; Umer, T.; Zanetti, A.; Chang, S.; Kropivnitskaya, A.; Nam, S. K.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Kong, D. J.; Lee, S.; Oh, Y. D.; Park, H.; Sakharov, A.; Son, D. C.; Kim, T. J.; Kim, J. 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V.; Moisenz, P.; Palichik, V.; Perelygin, V.; Shmatov, S.; Smirnov, V.; Tikhonenko, E.; Zarubin, A.; Golovtsov, V.; Ivanov, Y.; Kim, V.; Levchenko, P.; Murzin, V.; Oreshkin, V.; Smirnov, I.; Sulimov, V.; Uvarov, L.; Vavilov, S.; Vorobyev, A.; Vorobyev, An.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Kirsanov, M.; Krasnikov, N.; Pashenkov, A.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Safronov, G.; Semenov, S.; Spiridonov, A.; Stolin, V.; Vlasov, E.; Zhokin, A.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Leonidov, A.; Mesyats, G.; Rusakov, S. V.; Vinogradov, A.; Belyaev, A.; Boos, E.; Ershov, A.; Gribushin, A.; Khein, L.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Lukina, O.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Tourtchanovitch, L.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Ekmedzic, M.; Milosevic, J.; Rekovic, V.; Alcaraz Maestre, J.; Battilana, C.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Domínguez Vázquez, D.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro De Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Albajar, C.; de Trocóniz, J. F.; Missiroli, M.; Moran, D.; Brun, H.; Cuevas, J.; Fernandez Menendez, J.; Folgueras, S.; Gonzalez Caballero, I.; Brochero Cifuentes, J. A.; Cabrillo, I. J.; Calderon, A.; Duarte Campderros, J.; Fernandez, M.; Gomez, G.; Graziano, A.; Lopez Virto, A.; Marco, J.; Marco, R.; Martinez Rivero, C.; Matorras, F.; Munoz Sanchez, F. J.; Piedra Gomez, J.; Rodrigo, T.; Rodríguez-Marrero, A. Y.; Ruiz-Jimeno, A.; Scodellaro, L.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Bachtis, M.; Baillon, P.; Ball, A. H.; Barney, D.; Benaglia, A.; Bendavid, J.; Benhabib, L.; Benitez, J. F.; Bernet, C.; Bianchi, G.; Bloch, P.; Bocci, A.; Bonato, A.; Bondu, O.; Botta, C.; Breuker, H.; Camporesi, T.; Cerminara, G.; Colafranceschi, S.; D'Alfonso, M.; d'Enterria, D.; Dabrowski, A.; David, A.; De Guio, F.; De Roeck, A.; De Visscher, S.; Di Marco, E.; Dobson, M.; Dordevic, M.; Dorney, B.; Dupont-Sagorin, N.; Elliott-Peisert, A.; Eugster, J.; Franzoni, G.; Funk, W.; Gigi, D.; Gill, K.; Giordano, D.; Girone, M.; Glege, F.; Guida, R.; Gundacker, S.; Guthoff, M.; Hammer, J.; Hansen, M.; Harris, P.; Hegeman, J.; Innocente, V.; Janot, P.; Kousouris, K.; Krajczar, K.; Lecoq, P.; Lourenço, C.; Magini, N.; Malgeri, L.; Mannelli, M.; Marrouche, J.; Masetti, L.; Meijers, F.; Mersi, S.; Meschi, E.; Moortgat, F.; Morovic, S.; Mulders, M.; Musella, P.; Orsini, L.; Pape, L.; Perez, E.; Perrozzi, L.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Pimiä, M.; Piparo, D.; Plagge, M.; Racz, A.; Rolandi, G.; Rovere, M.; Sakulin, H.; Schäfer, C.; Schwick, C.; Sharma, A.; Siegrist, P.; Silva, P.; Simon, M.; Sphicas, P.; Spiga, D.; Steggemann, J.; Stieger, B.; Stoye, M.; Takahashi, Y.; Treille, D.; Tsirou, A.; Veres, G. I.; Vlimant, J. R.; Wardle, N.; Wöhri, H. K.; Wollny, H.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Renker, D.; Rohe, T.; Bachmair, F.; Bäni, L.; Bianchini, L.; Buchmann, M. A.; Casal, B.; Chanon, N.; Dissertori, G.; Dittmar, M.; Donegà, M.; Dünser, M.; Eller, P.; Grab, C.; Hits, D.; Hoss, J.; Lustermann, W.; Mangano, B.; Marini, A. C.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meister, D.; Mohr, N.; Nägeli, C.; Nessi-Tedaldi, F.; Pandolfi, F.; Pauss, F.; Peruzzi, M.; Quittnat, M.; Rebane, L.; Rossini, M.; Starodumov, A.; Takahashi, M.; Theofilatos, K.; Wallny, R.; Weber, H. A.; Amsler, C.; Canelli, M. F.; Chiochia, V.; De Cosa, A.; Hinzmann, A.; Hreus, T.; Kilminster, B.; Lange, C.; Millan Mejias, B.; Ngadiuba, J.; Robmann, P.; Ronga, F. J.; Taroni, S.; Verzetti, M.; Yang, Y.; Cardaci, M.; Chen, K. H.; Ferro, C.; Kuo, C. M.; Lin, W.; Lu, Y. J.; Volpe, R.; Yu, S. S.; Chang, P.; Chang, Y. 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R.; Luthra, A.; Malberti, M.; Nguyen, H.; Olmedo Negrete, M.; Shrinivas, A.; Sumowidagdo, S.; Wimpenny, S.; Andrews, W.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; D'Agnolo, R. T.; Evans, D.; Holzner, A.; Kelley, R.; Klein, D.; Lebourgeois, M.; Letts, J.; Macneill, I.; Olivito, D.; Padhi, S.; Palmer, C.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Sudano, E.; Tadel, M.; Tu, Y.; Vartak, A.; Welke, C.; Würthwein, F.; Yagil, A.; Barge, D.; Bradmiller-Feld, J.; Campagnari, C.; Danielson, T.; Dishaw, A.; Flowers, K.; Franco Sevilla, M.; Geffert, P.; George, C.; Golf, F.; Gouskos, L.; Incandela, J.; Justus, C.; Mccoll, N.; Richman, J.; Stuart, D.; To, W.; West, C.; Yoo, J.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Duarte, J.; Mott, A.; Newman, H. B.; Pena, C.; Rogan, C.; Spiropulu, M.; Timciuc, V.; Wilkinson, R.; Xie, S.; Zhu, R. Y.; Azzolini, V.; Calamba, A.; Carlson, B.; Ferguson, T.; Iiyama, Y.; Paulini, M.; Russ, J.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Ford, W. T.; Gaz, A.; Luiggi Lopez, E.; Nauenberg, U.; Smith, J. G.; Stenson, K.; Ulmer, K. A.; Wagner, S. R.; Alexander, J.; Chatterjee, A.; Chu, J.; Dittmer, S.; Eggert, N.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Ryd, A.; Salvati, E.; Skinnari, L.; Sun, W.; Teo, W. D.; Thom, J.; Thompson, J.; Tucker, J.; Weng, Y.; Winstrom, L.; Wittich, P.; Winn, D.; Abdullin, S.; Albrow, M.; Anderson, J.; Apollinari, G.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gao, Y.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hanlon, J.; Hare, D.; Harris, R. M.; Hirschauer, J.; Hooberman, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Kaadze, K.; Klima, B.; Kreis, B.; Kwan, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, T.; Lykken, J.; Maeshima, K.; Marraffino, J. M.; Martinez Outschoorn, V. I.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mishra, K.; Mrenna, S.; Musienko, Y.; Nahn, S.; Newman-Holmes, C.; O'Dell, V.; Prokofyev, O.; Sexton-Kennedy, E.; Sharma, S.; Soha, A.; Spalding, W. J.; Spiegel, L.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vidal, R.; Whitbeck, A.; Whitmore, J.; Yang, F.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Carver, M.; Cheng, T.; Curry, D.; Das, S.; De Gruttola, M.; Di Giovanni, G. P.; Field, R. D.; Fisher, M.; Furic, I. K.; Hugon, J.; Konigsberg, J.; Korytov, A.; Kypreos, T.; Low, J. F.; Matchev, K.; Milenovic, P.; Mitselmakher, G.; Muniz, L.; Rinkevicius, A.; Shchutska, L.; Snowball, M.; Sperka, D.; Yelton, J.; Zakaria, M.; Hewamanage, S.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Adams, T.; Askew, A.; Bochenek, J.; Diamond, B.; Haas, J.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Prosper, H.; Veeraraghavan, V.; Weinberg, M.; Baarmand, M. M.; Hohlmann, M.; Kalakhety, H.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Bazterra, V. E.; Berry, D.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Khalatyan, S.; Kurt, P.; Moon, D. H.; O'Brien, C.; Silkworth, C.; Turner, P.; Varelas, N.; Albayrak, E. A.; Bilki, B.; Clarida, W.; Dilsiz, K.; Duru, F.; Haytmyradov, M.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Rahmat, R.; Sen, S.; Tan, P.; Tiras, E.; Wetzel, J.; Yetkin, T.; Yi, K.; Barnett, B. A.; Blumenfeld, B.; Bolognesi, S.; Fehling, D.; Gritsan, A. V.; Maksimovic, P.; Martin, C.; Swartz, M.; Baringer, P.; Bean, A.; Benelli, G.; Bruner, C.; Kenny, R. P.; Malek, M.; Murray, M.; Noonan, D.; Sanders, S.; Sekaric, J.; Stringer, R.; Wang, Q.; Wood, J. S.; Barfuss, A. F.; Chakaberia, I.; Ivanov, A.; Khalil, S.; Makouski, M.; Maravin, Y.; Saini, L. K.; Shrestha, S.; Skhirtladze, N.; Svintradze, I.; Gronberg, J.; Lange, D.; Rebassoo, F.; Wright, D.; Baden, A.; Belloni, A.; Calvert, B.; Eno, S. C.; Gomez, J. A.; Hadley, N. J.; Kellogg, R. G.; Kolberg, T.; Lu, Y.; Marionneau, M.; Mignerey, A. C.; Pedro, K.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Barbieri, R.; Bauer, G.; Busza, W.; Cali, I. A.; Chan, M.; Di Matteo, L.; Dutta, V.; Gomez Ceballos, G.; Goncharov, M.; Gulhan, D.; Klute, M.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Ma, T.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Stephans, G. S. F.; Stöckli, F.; Sumorok, K.; Velicanu, D.; Veverka, J.; Wyslouch, B.; Yang, M.; Zanetti, M.; Zhukova, V.; Dahmes, B.; Gude, A.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Mans, J.; Pastika, N.; Rusack, R.; Singovsky, A.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Gonzalez Suarez, R.; Keller, J.; Knowlton, D.; Kravchenko, I.; Lazo-Flores, J.; Malik, S.; Meier, F.; Snow, G. R.; Zvada, M.; Dolen, J.; Godshalk, A.; Iashvili, I.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Haley, J.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Trocino, D.; Wang, R.-J.; Wood, D.; Zhang, J.; Hahn, K. A.; Kubik, A.; Mucia, N.; Odell, N.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Sung, K.; Velasco, M.; Won, S.; Brinkerhoff, A.; Chan, K. M.; Drozdetskiy, A.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Luo, W.; Lynch, S.; Marinelli, N.; Pearson, T.; Planer, M.; Ruchti, R.; Valls, N.; Wayne, M.; Wolf, M.; Woodard, A.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Hill, C.; Hughes, R.; Kotov, K.; Ling, T. Y.; Puigh, D.; Rodenburg, M.; Smith, G.; Winer, B. L.; Wolfe, H.; Wulsin, H. W.; Driga, O.; Elmer, P.; Hebda, P.; Hunt, A.; Koay, S. A.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Piroué, P.; Quan, X.; Saka, H.; Stickland, D.; Tully, C.; Werner, J. S.; Zuranski, A.; Brownson, E.; Mendez, H.; Ramirez Vargas, J. E.; Barnes, V. E.; Benedetti, D.; Bortoletto, D.; De Mattia, M.; Gutay, L.; Hu, Z.; Jha, M. K.; Jones, M.; Jung, K.; Kress, M.; Leonardo, N.; Lopes Pegna, D.; Maroussov, V.; Miller, D. H.; Neumeister, N.; Radburn-Smith, B. C.; Shi, X.; Shipsey, I.; Silvers, D.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Yoo, H. D.; Zablocki, J.; Zheng, Y.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Ecklund, K. M.; Geurts, F. J. M.; Li, W.; Michlin, B.; Padley, B. P.; Redjimi, R.; Roberts, J.; Zabel, J.; Betchart, B.; Bodek, A.; Covarelli, R.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Ferbel, T.; Garcia-Bellido, A.; Goldenzweig, P.; Han, J.; Harel, A.; Khukhunaishvili, A.; Petrillo, G.; Vishnevskiy, D.; Ciesielski, R.; Demortier, L.; Goulianos, K.; Lungu, G.; Mesropian, C.; Arora, S.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Kaplan, S.; Lath, A.; Panwalkar, S.; Park, M.; Patel, R.; Salur, S.; Schnetzer, S.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Rose, K.; Spanier, S.; York, A.; Bouhali, O.; Castaneda Hernandez, A.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Khotilovich, V.; Krutelyov, V.; Montalvo, R.; Osipenkov, I.; Pakhotin, Y.; Perloff, A.; Roe, J.; Rose, A.; Safonov, A.; Sakuma, T.; Suarez, I.; Tatarinov, A.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kovitanggoon, K.; Kunori, S.; Lee, S. W.; Libeiro, T.; Volobouev, I.; Appelt, E.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Johns, W.; Maguire, C.; Mao, Y.; Melo, A.; Sharma, M.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Arenton, M. W.; Boutle, S.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Lin, C.; Neu, C.; Wood, J.; Clarke, C.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Sturdy, J.; Belknap, D. A.; Carlsmith, D.; Cepeda, M.; Dasu, S.; Dodd, L.; Duric, S.; Friis, E.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Lazaridis, C.; Levine, A.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ross, I.; Sarangi, T.; Savin, A.; Smith, W. H.; Taylor, D.; Verwilligen, P.; Vuosalo, C.; Woods, N.; CMS Collaboration

2015-07-01

Measurements of diffractive dissociation cross sections in p p collisions at √{s }=7 TeV are presented in kinematic regions defined by the masses MX and MY of the two final-state hadronic systems separated by the largest rapidity gap in the event. Differential cross sections are measured as a function of ξX=MX2/s in the region -5.5 3 , log10MX>1.1 , and log10MY>1.1 , a region dominated by DD. The cross sections integrated over these regions are found to be, respectively, 2.99 ±0.02 (stat)-0.29+0.32(syst) mb , 1.18 ±0.02 (stat) ±0.13 (syst) mb , and 0.58 ±0.01 (stat)-0.11+0.13(syst) mb , and are used to extract extrapolated total SD and DD cross sections. In addition, the inclusive differential cross section, d σ /d Δ ηF , for events with a pseudorapidity gap adjacent to the edge of the detector, is measured over Δ ηF=8.4 units of pseudorapidity. The results are compared to those of other experiments and to theoretical predictions and found compatible with slowly rising diffractive cross sections as a function of center-of-mass energy.

CO₂ processing and hydration of fruit and vegetable tissues by clathrate hydrate formation.

PubMed

Takeya, Satoshi; Nakano, Kohei; Thammawong, Manasikan; Umeda, Hiroki; Yoneyama, Akio; Takeda, Tohoru; Hyodo, Kazuyuki; Matsuo, Seiji

2016-08-15

CO2 hydrate can be used to preserve fresh fruits and vegetables, and its application could contribute to the processing of carbonated frozen food. We investigated water transformation in the frozen tissue of fresh grape samples upon CO2 treatment at 2-3 MPa and 3°C for up to 46 h. Frozen fresh bean, radish, eggplant and cucumber samples were also investigated for comparison. X-ray diffraction indicated that after undergoing CO2 treatment for several hours, structure I CO2 hydrate formed within the grape tissue. Phase-contrast X-ray imaging using the diffraction-enhanced imaging technique revealed the presence of CO2 hydrate within the intercellular spaces of these tissues. The carbonated produce became effervescent because of the dissociation of CO2 hydrate through the intercellular space, especially above the melting point of ice. In addition, suppressed metabolic activity resulting from CO2 hydrate formation, which inhibits water and nutrient transport through intercellular space, can be expected. Copyright © 2016 Elsevier Ltd. All rights reserved.

Observation of quantum interferences via light-induced conical intersections in diatomic molecules

DOE PAGES

Natan, Adi; Ware, Matthew R.; Prabhudesai, Vaibhav S.; ...

2016-04-07

We observe energy-dependent angle-resolved diffraction patterns in protons from strong-field dissociation of the molecular hydrogen ion H + 2. The interference is a characteristic of dissociation around a laser-induced conical intersection (LICI), which is a point of contact between two surfaces in the dressed 2-dimensional Born-Oppenheimer potential energy landscape of a diatomic molecule in a strong laser field. The interference magnitude and angular period depend strongly on the energy difference between the initial state and the LICI, consistent with coherent diffraction around a cone-shaped potential barrier whose width and thickness depend on the relative energy of the initial state andmore » the cone apex. As a result, these findings are supported by numerical solutions of the time-dependent Schrodinger equation for similar experimental conditions.« less

Observation of quantum interferences via light-induced conical intersections in diatomic molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Natan, Adi; Ware, Matthew R.; Prabhudesai, Vaibhav S.

We observe energy-dependent angle-resolved diffraction patterns in protons from strong-field dissociation of the molecular hydrogen ion H + 2. The interference is a characteristic of dissociation around a laser-induced conical intersection (LICI), which is a point of contact between two surfaces in the dressed 2-dimensional Born-Oppenheimer potential energy landscape of a diatomic molecule in a strong laser field. The interference magnitude and angular period depend strongly on the energy difference between the initial state and the LICI, consistent with coherent diffraction around a cone-shaped potential barrier whose width and thickness depend on the relative energy of the initial state andmore » the cone apex. As a result, these findings are supported by numerical solutions of the time-dependent Schrodinger equation for similar experimental conditions.« less

Dynamics of reflection high-energy electron diffraction intensity oscillations during molecular beam epitaxial growth of GaAs on (111)B GaAs substrates

NASA Astrophysics Data System (ADS)

Yen, M. Y.; Haas, T. W.

1990-06-01

We have observed intensity oscillations in reflection high-energy electron diffraction during molecular beam epitaxial growth of GaAs on (111)B GaAs substrates. These oscillations only exist over a narrow range of growth conditions and their behavior is strongly dependent on the migration kinetics of group III and the molecular dissociative reaction of group V elements.

Elastic and Diffractive Scattering - Proceedings of the International Conference on Vth Blois Workshop

NASA Astrophysics Data System (ADS)

Kang, K.; Fried, H. M.; Tan, C.-I.

1994-02-01

The Table of Contents for the book is as follows: * Preface * `Overview' on Elastic Scattering and Total Cross-Sections * A Precise Measurement of the Real Part of the Elastic Scattering Amplitude at the {S bar{p}pS} * Luminosity Dependent Measurement of the p bar{p} Total Cross Section at √{s} = 541 GeV * Status of Fermilab E-710 * Luminosity-Independent Measurement of bar{p}p Elastic Scattering, Single Diffraction, Dissociation and Total Cross Section at √{s} = 546 and 1800 GeV * Phase Relations Revisited: A Challenge for SSC and LHC * Status of Near-Forward Elastic Scattering * bar{p}p Collisions at √{s} = 1.8 TeV: p, σt and B * p bar{p} Forward Scattering Parameters Results from Fermilab E760 * Photoproduction Results from H1 at HERA * Total and Jet Photoproduction Cross Sections at HERA and Fermilab * Minijet Model for High Energy γp Cross Sections * The Pomeron as Massive Gluons * Large N Theories with Glueball-like Spectra * Unitarity Relations for Gluonic Pomeron * The Donnachie-Landshoff Pomeron vs. QCD * The Odderon Intercept in Perturbative QCD * Theoret. and Phenomenol. Aspects of the Odderon * First Theorist's Gaze at HERA Data at Low xB * H1 Results for Structure Functions at Small x * Partial Photoproduction Cross Sections at √{s} ≈prox 180 GeV and First Results on F2 of the Proton from the ZEUS Experiment * Observation of a New Class of Events in Deep Inelastic Scattering * Jet Production in Muon-Proton and Muon-Nuclei Scattering at Fermilab-E665 * D0 Studies of Perturbative QCD * Large Rapidity Gaps and Single Diffraction Dissociation in High Energy pp and bar{p}p Collisions * Hadron and Reggeon Structure in High Energy Collisions * Monte Carlo Studies of Diffractive Processes in Deep Inelastic Scattering * Elastic Parton-Parton Amplitudes in Geometrical Models * Non-Perturbative QCD Calculations of High-Energy Observables * Effective Field Theory for Diffractive QCD Processes * High Energy Behavior of σtot, ρ, and B - Asymptotic Amplitude Analysis and a QCD-Inspired Analysis * Rapidity Gaps and Multiplicity Fluctuations * Branching Processes and Multi-Particle Production * High Energy Elastic Scattering and Nucleon as a Topological Soliton * The Behavior of Cross Sections at Very High Energies * The Pomeron and QCD with Many Light Quarks * Heterotic Pomeron: High Energy Hadronic Collisions in QCD * CDF Results on Electroweak Physics * DØ Results on Electroweak Physics * Search for the Top Quark and Other New Particles at DØ * Rapidity Gaps and Forward Physics at DØ * High Energy Asymptotics of Perturbative Multi-Color QCD * Rapidity Gaps in e+e- Collisions * Large Rapidity Gap, Jet Events at HERA: a PQCD Approach * High Energy Parton-Parton Elastic Scattering in QCD * Parton-Parton Elastic Scattering and Rapidity Gaps at Tevatron Energies * Hard Elastic Scattering * Hard Diffractive Processes * Three Successful Tests of Color Transparency and Nuclear Filtering * New KNO in QCD * A Chiral Condensate Search at the Tevatron * Cosmic Ray Evidences for Aligned High Energy Jets at Supertevatron Energy and Hard DDD * "New Hadronic State" Observed in Extremely High Energy Cosmic-Ray Interactions * Meson and Nucleon Form Factors in PQCD * Elastic Charge Form Factors for Pseudoscalar Mesons * The Ultimate Experiment * Search for Coherent Charm Production in 800 GeV/c Proton-Silicon Interactions * Chiral Quark Model and Hadron Scattering * Elastic Spin Experiments at UNK, Fermilab and SSC * Spin-Flip in Elastic and Diffractive Scattering * FNAL Polarized Beams and Spin Dependence at RHIC * Particle Tracking in the Close-to-Forward Region (η > 5.5) * Blois V: Experimental Summary * Blois V: Summary Talk * List of Participants

Influence of Crystallinity and Energetics on Charge Separation in Polymer–Inorganic Nanocomposite Films for Solar Cells

PubMed Central

Bansal, Neha; Reynolds, Luke X.; MacLachlan, Andrew; Lutz, Thierry; Ashraf, Raja Shahid; Zhang, Weimin; Nielsen, Christian B.; McCulloch, Iain; Rebois, Dylan G.; Kirchartz, Thomas; Hill, Michael S.; Molloy, Kieran C.; Nelson, Jenny; Haque, Saif A.

2013-01-01

The dissociation of photogenerated excitons and the subsequent spatial separation of the charges are of crucial importance to the design of efficient donor-acceptor heterojunction solar cells. While huge progress has been made in understanding charge generation at all-organic junctions, the process in hybrid organic:inorganic systems has barely been addressed. Here, we explore the influence of energetic driving force and local crystallinity on the efficiency of charge pair generation at hybrid organic:inorganic semiconductor heterojunctions. We use x-ray diffraction, photoluminescence quenching, transient absorption spectroscopy, photovoltaic device and electroluminescence measurements to demonstrate that the dissociation of photogenerated polaron pairs at hybrid heterojunctions is assisted by the presence of crystalline electron acceptor domains. We propose that such domains encourage delocalization of the geminate pair state. The present findings suggest that the requirement for a large driving energy for charge separation is relaxed when a more crystalline electron acceptor is used. PMID:23524906

Dissociative Functions in the Normal Mourning Process.

ERIC Educational Resources Information Center

Kauffman, Jeffrey

1994-01-01

Sees dissociative functions in mourning process as occurring in conjunction with integrative trends. Considers initial shock reaction in mourning as model of normal dissociation in mourning process. Dissociation is understood to be related to traumatic significance of death in human consciousness. Discerns four psychological categories of…

Doped indium nitride thin film by sol-gel spin coating method

NASA Astrophysics Data System (ADS)

Lee, Hui San; Ng, Sha Shiong; Yam, Fong Kwong

2017-12-01

In this study, magnesium doped indium nitride (InN:Mg) thin films grown on silicon (100) substrate were prepared via sol-gel spin coating method followed by nitridation process. A custom-made tube furnace was used to perform the nitridation process. Through this method, the low dissociation temperature issue of InN:Mg thin films can be solved. The deposited InN:Mg thin films were investigated using various techniques. The X-rays diffraction results revealed that two intense diffraction peaks correspond to wurtzite structure InN (100), and InN (101) were observed at 29° and 33.1° respectively. Field emission scanning electron microscopy images showed that the surface of the films exhibits densely packed grains. The elemental composition of the deposited thin films was analyzed using energy dispersive X-rays spectroscopy. The detected atomic percentages for In, N, and Mg were 43.22 %, 3.28 %, and 0.61 % respectively. The Raman spectra showed two Raman- and infrared-active modes of E2 (High) and A1 (LO) of the wurtzite InN. The band gap obtained from the Tauc plot showed around 1.74 eV. Lastly, the average surface roughness measured by AFM was around 0.133 µm.

A theoretical study of the structure and thermochemical properties of alkali metal fluoroplumbates MPbF3.

PubMed

Boltalin, A I; Korenev, Yu M; Sipachev, V A

2007-07-19

Molecular constants of MPbF3 (M=Li, Na, K, Rb, and Cs) were calculated theoretically at the MP2(full) and B3LYP levels with the SDD (Pb, K, Rb, and Cs) and cc-aug-pVQZ (F, Li, and Na) basis sets to determine the thermochemical characteristics of the substances. Satisfactory agreement with experiment was obtained, including the unexpected nonmonotonic dependence of substance dissociation energies on the alkali metal atomic number. The bond lengths of the theoretical CsPbF3 model were substantially elongated compared with experimental estimates, likely because of errors in both theoretical calculations and electron diffraction data processing.

Cognitive processes in dissociation: comment on Giesbrecht et al. (2008).

PubMed

Bremner, J Douglas

2010-01-01

In their recent review "Cognitive Processes in Dissociation: An Analysis of Core Theoretical Assumptions," published in Psychological Bulletin, Giesbrecht, Lynn, Lilienfeld, and Merckelbach have challenged the widely accepted trauma theory of dissociation, which holds that dissociative symptoms are caused by traumatic stress. In doing so, the authors have outlined a series of links between various constructs--such as fantasy proneness, cognitive failures, absorption, suggestibility, altered information-processing, dissociation, and amnesia--claiming that these linkages lead to the false conclusion that trauma causes dissociation. A review of the literature, however, shows that these are not necessarily related constructs. Careful examination of their arguments reveals no basis for the conclusion that there is no association between trauma and dissociation. The current comment offers a critical review and rebuttal of Giesbrecht et al.'s argument that there is no relationship between trauma and dissociation.

Dissociative tendencies and facilitated emotional processing.

PubMed

Oathes, Desmond J; Ray, William J

2008-10-01

Dissociation is a process linked to lapses of attention, history of abuse or trauma, compromised emotional memory, and a disintegrated sense of self. It is theorized that dissociation stems from avoiding emotional information, especially negative emotion, to protect a fragile psyche. The present study tested whether or not dissociaters do actually avoid processing emotion by asking groups scoring high or low on the Dissociative Experiences Scale to judge the affective valence of several types of emotional stimuli. Manipulations of valence, modality (pictures or words), task complexity, and personal relevance lead to results suggesting that dissociation is linked to facilitated rather than deficient emotional processing. Our results are consistent with a theory that sensitivity to emotional material may be a contributing factor in subsequent dissociation to avoid further elaboration of upsetting emotion in these individuals. The findings for dissociation further exemplify the influence of individual differences in the link between cognition and emotion. (c) 2008 APA, all rights reserved

Cognitive Processes in Dissociation: An Analysis of Core Theoretical Assumptions

ERIC Educational Resources Information Center

Giesbrecht, Timo; Lilienfield, Scott O.; Lynn, Steven Jay; Merckelbach, Harald

2008-01-01

Dissociation is typically defined as the lack of normal integration of thoughts, feelings, and experiences into consciousness and memory. The present article critically evaluates the research literature on cognitive processes in dissociation. The authors' review indicates that dissociation is characterized by subtle deficits in neuropsychological…

Speech-Language Dissociations, Distractibility, and Childhood Stuttering

PubMed Central

Conture, Edward G.; Walden, Tedra A.; Lambert, Warren E.

2015-01-01

Purpose This study investigated the relation among speech-language dissociations, attentional distractibility, and childhood stuttering. Method Participants were 82 preschool-age children who stutter (CWS) and 120 who do not stutter (CWNS). Correlation-based statistics (Bates, Appelbaum, Salcedo, Saygin, & Pizzamiglio, 2003) identified dissociations across 5 norm-based speech-language subtests. The Behavioral Style Questionnaire Distractibility subscale measured attentional distractibility. Analyses addressed (a) between-groups differences in the number of children exhibiting speech-language dissociations; (b) between-groups distractibility differences; (c) the relation between distractibility and speech-language dissociations; and (d) whether interactions between distractibility and dissociations predicted the frequency of total, stuttered, and nonstuttered disfluencies. Results More preschool-age CWS exhibited speech-language dissociations compared with CWNS, and more boys exhibited dissociations compared with girls. In addition, male CWS were less distractible than female CWS and female CWNS. For CWS, but not CWNS, less distractibility (i.e., greater attention) was associated with more speech-language dissociations. Last, interactions between distractibility and dissociations did not predict speech disfluencies in CWS or CWNS. Conclusions The present findings suggest that for preschool-age CWS, attentional processes are associated with speech-language dissociations. Future investigations are warranted to better understand the directionality of effect of this association (e.g., inefficient attentional processes → speech-language dissociations vs. inefficient attentional processes ← speech-language dissociations). PMID:26126203

Cognitive Processes in Dissociation: Comment on Giesbrecht et al. (2008)

ERIC Educational Resources Information Center

Bremner, J. Douglas

2010-01-01

In their recent review "Cognitive Processes in Dissociation: An Analysis of Core Theoretical Assumptions," published in "Psychological Bulletin", Giesbrecht, Lynn, Lilienfeld, and Merckelbach (2008) have challenged the widely accepted trauma theory of dissociation, which holds that dissociative symptoms are caused by traumatic stress. In doing so,…

Cognitive Processes in Dissociation: Comment on Giesbrecht et al. (2008)

PubMed Central

Bremner, J. Douglas

2010-01-01

In “Cognitive Processes in Dissociation: An Analysis of Core Theoretical Assumptions,” published in Psychological Bulletin, Giesbrecht, Lynn, Lilienfeld, and Merckelbach (2008) have challenged the widely accepted trauma theory of dissociation, which holds that dissociative symptoms are caused by traumatic stress. In doing so the authors outline a series of links between various constructs, such as fantasy proneness, cognitive failures, absorption, suggestibility, altered information-processing, dissociation, and amnesia, claiming that these linkages lead to the false conclusion that trauma causes dissociation. A review of the literature, however, shows that these are not necessarily related constructs. Careful examination of their arguments reveals no basis for the conclusion that there is no association between trauma and dissociation. The current comment offers a critical review and rebuttal of the argument of Giesbrecht et al. that there is no relationship between trauma and dissociation. PMID:20063920

Cognitive processes in dissociation: an analysis of core theoretical assumptions.

PubMed

Giesbrecht, Timo; Lynn, Steven Jay; Lilienfeld, Scott O; Merckelbach, Harald

2008-09-01

Dissociation is typically defined as the lack of normal integration of thoughts, feelings, and experiences into consciousness and memory. The present article critically evaluates the research literature on cognitive processes in dissociation. The authors' review indicates that dissociation is characterized by subtle deficits in neuropsychological performance (e.g., heightened distractibility). Some of the cognitive phenomena (e.g., weakened cognitive inhibition) associated with dissociation appear to be dependent on the emotional or attentional context. Contrary to a widespread assumption in the clinical literature, dissociation does not appear to be related to avoidant information processing. Rather, it is associated with an enhanced propensity toward pseudo-memories, possibly mediated by heightened levels of interrogative suggestibility, fantasy proneness, and cognitive failures. Evidence for a link between dissociation and either memory fragmentation or early trauma based on objective measures is conspicuously lacking. The authors identify a variety of methodological issues and discrepancies that make it difficult to articulate a comprehensive framework for cognitive mechanisms in dissociation. The authors conclude with a discussion of research domains (e.g., sleep-related experiences, drug-related dissociation) that promise to advance our understanding of cognition and dissociation.

Hadron production in diffractive deep-inelastic scattering

NASA Astrophysics Data System (ADS)

H1 Collaboration; Adloff, C.; Aid, S.; Anderson, M.; Andreev, V.; Andrieu, B.; Arkadov, V.; Arndt, C.; Ayyaz, I.; Babaev, A.; Bähr, J.; Bán, J.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Bassler, U.; Bate, P.; Beck, M.; Beglarian, A.; Behrend, H.-J.; Beier, C.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bertrand-Coremans, G.; Beyer, R.; Biddulph, P.; Bizot, J. C.; Borras, K.; Boudry, V.; Braemer, A.; Braunschweig, W.; Brisson, V.; Brown, D. P.; Brückner, W.; Bruel, P.; Bruncko, D.; Brune, C.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Calvet, D.; Campbell, A. J.; Carli, T.; Chabert, E.; Charlet, M.; Clarke, D.; Clerbaux, B.; Cocks, S.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; de Roeck, A.; de Wolf, E. A.; Delcourt, B.; Diaconu, C.; Dirkmann, M.; Dixon, P.; Dlugosz, W.; Donovan, K. T.; Dowell, J. D.; Droutskoi, A.; Ebert, J.; Eckerlin, G.; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Elsen, E.; Enzenberger, M.; Erdmann, M.; Fahr, A. B.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flügge, G.; Fomenko, A.; Formánek, J.; Foster, J. M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gayler, J.; Gebauer, M.; Gerhards, R.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Gorelov, I.; Grab, C.; Grässler, H.; Greenshaw, T.; Griffiths, R. K.; Grindhammer, G.; Gruber, C.; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, T.; Hampel, M.; Haustein, V.; Haynes, W. J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herynek, I.; Hewitt, K.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Höppner, M.; Hoffmann, D.; Holtom, T.; Horisberger, R.; Hudgson, V. L.; Hütte, M.; Ibbotson, M.; Isolarş Sever, Ç.; Itterbeck, H.; Jacquet, M.; Jaffre, M.; Janoth, J.; Jansen, D. M.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kander, M.; Kant, D.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kaufmann, O.; Kausch, M.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhne, J. H.; Kolanoski, H.; Kolya, S. D.; Korbel, V.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Küpper, A.; Küster, H.; Kuhlen, M.; Kurča, T.; Laforge, B.; Lahmann, R.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Lebedev, A.; Lehmann, M.; Lehner, F.; Lemaitre, V.; Levonian, S.; Lindstroem, M.; Lipinski, J.; List, B.; Lobo, G.; Lubimov, V.; Lüke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Krüger, H.; Malinovski, E.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martin, G.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Maxfield, S. J.; McMahon, S. J.; McMahon, T. R.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Migliori, A.; Mikocki, S.; Milstead, D.; Moeck, J.; Mohr, R.; Mohrdieck, S.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, D.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Négri, I.; Newman, P. R.; Newton, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Niggli, H.; Nix, O.; Nowak, G.; Nunnemann, T.; Oberlack, H.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panaro, E.; Panitch, A.; Pascaud, C.; Passaggio, S.; Patel, G. D.; Pawletta, H.; Peppel, E.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pöschl, R.; Pope, G.; Povh, B.; Rabbertz, K.; Reimer, P.; Reisert, B.; Rick, H.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Schacht, P.; Scheins, J.; Schiek, S.; Schleif, S.; Schleper, P.; von Schlippe, W.; Schmidt, D.; Schmidt, G.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwab, B.; Sefkow, F.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Sloan, T.; Smirnov, P.; Smith, M.; Solochenko, V.; Soloviev, Y.; Specka, A.; Spiekermann, J.; Spitzer, H.; Squinabol, F.; Steffen, P.; Steinberg, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Stolze, K.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Swart, M.; Tapprogge, S.; Taševský, M.; Tchernyshov, V.; Tchetchelnitski, S.; Theissen, J.; Thompson, G.; Thompson, P. D.; Tobien, N.; Todenhagen, R.; Truöl, P.; Tsipolitis, G.; Turnau, J.; Tzamariudaki, E.; Udluft, S.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; van Esch, P.; van Mechelen, P.; Vazdik, Y.; Villet, G.; Wacker, K.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wiesand, S.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wittmann, E.; Wobisch, M.; Wollatz, H.; Wünsch, E.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zini, P.; Zomer, F.; Zsembery, J.; Zurnedden, M.

1998-05-01

Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the photon dissociation system: the hadronic energy flow, the Feynman-x (xF) variable for charged particles, the squared transverse momentum of charged particles (pT*2), and the mean pT*2 as a function of xF. These distributions are compared with results in the γ*p centre-of-mass frame from inclusive deep-inelastic scattering in the fixed-target experiment EMC, and also with the predictions of several Monte Carlo calculations. The data are consistent with a picture in which the partonic structure of the diffractive exchange is dominated at low Q2 by hard gluons.

Phase transformation from cubic ZnS to hexagonal ZnO by thermal annealing

NASA Astrophysics Data System (ADS)

Mahmood, K.; Asghar, M.; Amin, N.; Ali, Adnan

2015-03-01

We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by high-temperature thermal annealing. The ZnS thin films were grown on Si (001) substrate by thermal evaporation system using ZnS powder as source material. The grown films were annealed at different temperatures and characterized by X-ray diffraction (XRD), photoluminescence (PL), four-point probe, scanning electron microscope (SEM) and energy dispersive X-ray diffraction (EDX). The results demonstrated that as-deposited ZnS film has mixed phases but high-temperature annealing leads to transition from ZnS to ZnO. The observed result can be explained as a two-step process: (1) high-energy O atoms replaced S atoms in lattice during annealing process, and (2) S atoms diffused into substrate and/or diffused out of the sample. The dissociation energy of ZnS calculated from the Arrhenius plot of 1000/T versus log (resistivity) was found to be 3.1 eV. PL spectra of as-grown sample exhibits a characteristic green emission at 2.4 eV of ZnS but annealed samples consist of band-to-band and defect emission of ZnO at 3.29 eV and 2.5 eV respectively. SEM and EDX measurements were additionally performed to strengthen the argument.

Distinct water activation on polar/non-polar facets of ZnO nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, He; Sun, Junming; Liu, Changjun

2015-11-01

ZnO nanoparticles with differing dominant facets were prepared and characterized by a complimentary of techniques such as X-ray diffraction, electron microscopy, temperature programmed desorption of H2O, and Fourier transform infrared spectroscopy analysis of adsorbed D2O. For the first time, water interaction/activation is compared on ZnO polar and non-polar facets. We report that non-polar facets exhibit high activity in water activation, which favors reactions such as ketonization and steam reforming in which dissociated water is involved. The distinct water dissociation on ZnO non-polar facets could be related to its facile formation of oxygen vacancies under realistic reaction conditions.

ab initio calculation of the rate of vibrational relaxation and thermal dissociation of hydrogen by helium at high temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dove, J.E.; Raynor, S.

The master equation for the thermal dissociation of para-H/sub 2/ infinitely dilute in He, was solved for temperatures of 1000 to 10,000/sup 0/K. Transition probabilities, used in the master equation, were obtained, in the case of energy transfer transitions, from distorted wave and quasi-classical trajectory calculations and, for dissociative processes, from trajectory calculations alone. An ab initio potential was used. From the solution, values of the dissociation rate constant, vibrational relaxation times, and incubation times for dissociation and vibrational relaxation were calculated. The sensitivity of the calculated results to variations in the transition probabilities was examined. Vibrational relaxation is mostmore » sensitive to simultaneous transitions in vibration and rotation (VRT processes); pure rotational (RT) transitions also have a substantial effect. Dissociation is most strongly affected by RT processes, but changes in VRT and groups of dissociative transitions also have a significant effect. However complete suppression of all dissociative transitions except those from levels immediately next to the continuum lowers the dissociation rates only by a factor of about 2. The location of the dissociation ''bottleneck'' is discussed. 5 figures, 3 tables.« less

Signature of dislocations and stacking faults of face-centred cubic nanocrystals in coherent X-ray diffraction patterns: a numerical study.

PubMed

Dupraz, Maxime; Beutier, Guillaume; Rodney, David; Mordehai, Dan; Verdier, Marc

2015-06-01

Crystal defects induce strong distortions in diffraction patterns. A single defect alone can yield strong and fine features that are observed in high-resolution diffraction experiments such as coherent X-ray diffraction. The case of face-centred cubic nanocrystals is studied numerically and the signatures of typical defects close to Bragg positions are identified. Crystals of a few tens of nanometres are modelled with realistic atomic potentials and 'relaxed' after introduction of well defined defects such as pure screw or edge dislocations, or Frank or prismatic loops. Diffraction patterns calculated in the kinematic approximation reveal various signatures of the defects depending on the Miller indices. They are strongly modified by the dissociation of the dislocations. Selection rules on the Miller indices are provided, to observe the maximum effect of given crystal defects in the initial and relaxed configurations. The effect of several physical and geometrical parameters such as stacking fault energy, crystal shape and defect position are discussed. The method is illustrated on a complex structure resulting from the simulated nanoindentation of a gold nanocrystal.

Signature of dislocations and stacking faults of face-centred cubic nanocrystals in coherent X-ray diffraction patterns: a numerical study1

PubMed Central

Dupraz, Maxime; Beutier, Guillaume; Rodney, David; Mordehai, Dan; Verdier, Marc

2015-01-01

Crystal defects induce strong distortions in diffraction patterns. A single defect alone can yield strong and fine features that are observed in high-resolution diffraction experiments such as coherent X-ray diffraction. The case of face-centred cubic nanocrystals is studied numerically and the signatures of typical defects close to Bragg positions are identified. Crystals of a few tens of nanometres are modelled with realistic atomic potentials and ‘relaxed’ after introduction of well defined defects such as pure screw or edge dislocations, or Frank or prismatic loops. Diffraction patterns calculated in the kinematic approximation reveal various signatures of the defects depending on the Miller indices. They are strongly modified by the dissociation of the dislocations. Selection rules on the Miller indices are provided, to observe the maximum effect of given crystal defects in the initial and relaxed configurations. The effect of several physical and geometrical parameters such as stacking fault energy, crystal shape and defect position are discussed. The method is illustrated on a complex structure resulting from the simulated nanoindentation of a gold nanocrystal. PMID:26089755

Information processing of an acquaintance rape scenario among high- and low-dissociating college women.

PubMed

Sandberg, D A; Lynn, S J; Matorin, A I

2001-07-01

To assess the impact of dissociation on information processing, 66 college women with high and low levels of trait dissociation were studied with regard to how they unitized videotape segments of an acquaintance rape scenario (actual assault not shown) and a nonthreatening control scenario. Unitization is a paradigm that measures how actively people process stimuli by recording how many times they press a button to indicate that they have seen a significant or meaningful event. Trait dissociation was negatively correlated with participants' unitization of the acquaintance rape videotape, unitization was positively correlated with danger cue identification, and state dissociation was negatively correlated with dangerousness ratings.

Influence of Au and TiO2 structures on hydrogen dissociation over TiO2/Au(100)

NASA Astrophysics Data System (ADS)

Nakamura, I.; Mantoku, H.; Furukawa, T.; Takahashi, A.; Fujitani, T.

2012-11-01

We performed H2-D2 exchange reactions over TiOx/Au(100) and compared the observed reaction kinetics with those reported for TiOx/Au(111) in order to clarify the influence of the Au and TiO2 structures on dissociation of H2 molecules. Low energy electron diffraction observations showed that the TiO2 produced on Au(100) was disordered, in contrast to the comparatively ordered TiO2 structure formed on Au(111). The activation energies and the turnover frequencies for HD formation over TiO2/Au(100) agreed well with those for TiO2/Au(111), clearly indicating that the hydrogen dissociation sites created over TiO2/Au(100) were the perimeter interface between stoichiometric TiO2 and Au, as was previously concluded for TiO2/Au(111). We concluded that the creation of active sites for hydrogen dissociation was independent of the Au and TiO2 structures consisting perimeter interface, and that local bonds that formed between Au and O atoms of stoichiometric TiO2 were essential for the creation of active sites.

Process dissociation and mixture signal detection theory.

PubMed

DeCarlo, Lawrence T

2008-11-01

The process dissociation procedure was developed in an attempt to separate different processes involved in memory tasks. The procedure naturally lends itself to a formulation within a class of mixture signal detection models. The dual process model is shown to be a special case. The mixture signal detection model is applied to data from a widely analyzed study. The results suggest that a process other than recollection may be involved in the process dissociation procedure.

Surface-induced dissociation of methanol cations: A non-ergodic process

DOE PAGES

Shukla, Anil K.

2017-09-01

Here, dissociation of methanol molecular cations, CH 3OH +, to CH 2OH + on collision with a self-assembled monolayer surface of fluorinated alkyl thiol on gold 111 crystal has been studied at 12.5 eV collision energy. Two energetically and spatially distinct processes contribute to the dissociation process: one involving loss of very large amount of energy approaching the initial kinetic energy of the primary ions with scattering of fragment ions over a broad angular range between surface normal and surface parallel while the second process results from small amount of energy loss with fragment ions scattered over a narrow angularmore » range close to the surface parallel. There is a third process with relatively small contribution to total dissociation whose characteristics are very similar to the low energy loss process. Finally, these results demonstrate that surface-induced dissociation of methanol cations via hydrogen loss is non-ergodic.« less

Surface-induced dissociation of methanol cations: A non-ergodic process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shukla, Anil K.

Here, dissociation of methanol molecular cations, CH 3OH +, to CH 2OH + on collision with a self-assembled monolayer surface of fluorinated alkyl thiol on gold 111 crystal has been studied at 12.5 eV collision energy. Two energetically and spatially distinct processes contribute to the dissociation process: one involving loss of very large amount of energy approaching the initial kinetic energy of the primary ions with scattering of fragment ions over a broad angular range between surface normal and surface parallel while the second process results from small amount of energy loss with fragment ions scattered over a narrow angularmore » range close to the surface parallel. There is a third process with relatively small contribution to total dissociation whose characteristics are very similar to the low energy loss process. Finally, these results demonstrate that surface-induced dissociation of methanol cations via hydrogen loss is non-ergodic.« less

Different urea stoichiometries between the dissociation and denaturation of tobacco mosaic virus as probed by hydrostatic pressure.

PubMed

Santos, Jose L R; Aparicio, Ricardo; Joekes, Inés; Silva, Jerson L; Bispo, Jose A C; Bonafe, Carlos F S

2008-05-01

Viruses are very efficient self-assembly structures, but little is understood about the thermodynamics governing their directed assembly. At higher levels of pressure or when pressure is combined with urea, denaturation occurs. For a better understanding of such processes, we investigated the apparent thermodynamic parameters of dissociation and denaturation by assuming a steady-state condition. These processes can be measured considering the decrease of light scattering of a viral solution due to the dissociation process, and the red shift of the fluorescence emission spectra, that occurs with the denaturation process. We determined the apparent urea stoichiometry considering the equilibrium reaction of TMV dissociation and subunit denaturation, which furnished, respectively, 1.53 and 11.1 mol of urea/mol of TMV subunit. The denaturation and dissociation conditions were arrived in a near reversible pathway, allowing the determination of thermodynamic parameters. Gel filtration HPLC, electron microscopy and circular dichroism confirmed the dissociation and denaturation processes. Based on spectroscopic results from earlier papers, the calculation of the apparent urea stoichiometry of dissociation and denaturation of several other viruses resulted in similar values, suggesting a similar virus-urea interaction among these systems.

Owning the past, claiming the present: perspectives on the treatment of dissociative patients.

PubMed

Middleton, Warwick

2005-03-01

From the early 1990s there has been a growing awareness in Australia of dissociative processes and dissociative disorders. The objective in this paper is to provide a selective overview of the context and process of treatment based on the substantive dissociative disorders literature, ongoing clinical experience and research, and over 8 years as director of a trauma and dissociation unit at Belmont Hospital, Brisbane. The construct of individual selfhood is of direct relevance in illustrating the psychological damage sustained by patients who have relied on dissociative defences to survive, and in highlighting issues and areas that are a particular focus of informed treatment.

Temperature Dependence of Dissociative Electron Attachment to Halogenated Hydrocarbons

NASA Astrophysics Data System (ADS)

Wang, Yicheng; Christophorou, Loucas G.

1996-10-01

Most of the gas mixtures currently in use for plasma processing of semiconductors involve halogenated hydrocarbons such as the strongly electronegative gases CCl4 and CFCl_3, the weakly electronegative gas CF_2Cl2 and the very weakly electronegative gases CHF3 and CF_4. Many dissociation processes are known to occur for these molecules. One of these dissociation reactions which is particularly effective for the strongly electronegative hydrocarbons is dissociative electron attachment. Even for weakly electron attaching gases, molecular dissociation via dissociative electron attachment at low energies can be an efficient dissociation process if the gas temperature is higher than ambient. Dissociative electron attachment is known to increase with increasing temperature above room temperature for many such compounds. In this paper, we report our measurements on the increases of the total electron attachment rate constant for CF_2Cl2 with increasing gas temperature from room temperature to about 600 K. -Research sponsored in part by the U.S. Air Force Wright Laboratory under contract F33615-96-C-2600 with the University of Tennessee. Also, Department of Physics, The University of Tennessee, Knoxville, TN.

EXAFS characterisation of metal bonding in highly luminescent, UV stable, water-soluble and biocompatible lanthanide complexes

NASA Astrophysics Data System (ADS)

Kalyakina, A.; Utochnikova, V.; Trigub, A.; Zubavichus, Y.; Kuzmina, N.; Bräse, S.

2016-05-01

The combination of X-ray diffraction with EXAFS was employed to assess the coordination environment of lanthanide complexes in solutions. This method is based on the assumption that the local structure of lanthanide complexes in solution combines elements of the crystal structure of the complex in the solid state (single- or polycrystalline) and the elements of the local structure of a lanthanide salt, completely dissociated in the solvent (usually chlorides). The success of this approach is demonstrated with the lanthanide (III) 2,3,4,5,6-pentafluorobenzoate complexes, where the local structure in aqueous and methanol solutions were estimated. Moreover, the dissociation degree of the complexes in aqueous and methanol solutions was evaluated.

Lost in dissociation: The main paradigms in unconscious cognition.

PubMed

Augusto, Luis M

2016-05-01

Contemporary studies in unconscious cognition are essentially founded on dissociation, i.e., on how it dissociates with respect to conscious mental processes and representations. This is claimed to be in so many and diverse ways that one is often lost in dissociation. In order to reduce this state of confusion we here carry out two major tasks: based on the central distinction between cognitive processes and representations, we identify and isolate the main dissociation paradigms; we then critically analyze their key tenets and reported findings. Copyright © 2016 Elsevier Inc. All rights reserved.

Dancing with the Muses: dissociation and flow.

PubMed

Thomson, Paula; Jaque, S Victoria

2012-01-01

This study investigated dissociative psychological processes and flow (dispositional and state) in a group of professional and pre-professional dancers (n=74). In this study, high scores for global (Mdn=4.14) and autotelic (Mdn=4.50) flow suggest that dancing was inherently integrating and rewarding, although 17.6% of the dancers were identified as possibly having clinical levels of dissociation (Dissociative Experiences Scale-Taxon cutoff score≥20). The results of the multivariate analysis of variance indicated that subjects with high levels of dissociation had significantly lower levels of global flow (p<.05). Stepwise linear regression analyses demonstrated that dispositional flow negatively predicted the dissociative constructs of depersonalization and taxon (p<.05) but did not significantly predict the variance in absorption/imagination (p>.05). As hypothesized, dissociation and flow seem to operate as different mental processes.

Does dissociation offer a useful explanation for psychopathology?

PubMed

Jureidini, Jon

2004-01-01

Dissociation is often conceptualised as an altered state of consciousness, a trance-like state in which normal barriers between conscious and unconscious memories, desires and beliefs break down and other amnestic barriers emerge. This review explores whether it is likely that there is a neurophysiology of pathological dissociative processes that will elucidate management. A critical reading of current research, sourced through Medline and Psychinfo searches from 1990 to 2002, using subject headings: dissociative disorders, hypnosis and stress disorder (post-traumatic), as well as keywords: dissociation, hypnosis and trance. Current knowledge does not support the notion of dissociation as a discrete brain state or process. Psychiatric and neurophysiological research and theory development are better directed towards individual components that contribute to dissociative experience. Copyright (c) 2004 S. Karger AG, Basel.

A process dissociation approach to objective-projective test score interrelationships.

PubMed

Bornstein, Robert F

2002-02-01

Even when self-report and projective measures of a given trait or motive both predict theoretically related features of behavior, scores on the 2 tests correlate modestly with each other. This article describes a process dissociation framework for personality assessment, derived from research on implicit memory and learning, which can resolve these ostensibly conflicting results. Research on interpersonal dependency is used to illustrate 3 key steps in the process dissociation approach: (a) converging behavioral predictions, (b) modest test score intercorrelations, and (c) delineation of variables that differentially affect self-report and projective test scores. Implications of the process dissociation framework for personality assessment and test development are discussed.

Contemporary concepts of dissociation.

PubMed

Avdibegović, Esmina

2012-10-01

The concept of dissociation was developed in the late 19th century by Pierre Janet for conditions of "double consciousness" in hypnosis, hysteria, spirit possession and mediumship. He defined dissociation as a deficit in the capacity of integration of two or more different "systems of ideas and functions that constitute personality", and suggested that it can be related to a genetic component, to severe illness and fatigue, and particularly to experiencing adverse, potentially traumatizing events. By the late 20th century, various and often contradictory concepts of dissociation were suggested, which were either insufficient or exceedingly including when compared to the original idea. Currently, dissociation is used to describe a wide range of normal and abnormal phenomena as a process in which behaviour, thoughts and emotions can become separated one from another. A complete presentation of mechanisms involved in dissociation is still unknown. Scientific research on basic processes of dissociation is derived mainly from studies of hypnosis and post-traumatic stress disorder. Given the controversies in modern concepts of dissociation, some researchers and theorists suggest return to the original understanding of dissociation as a basic premise for the further development of the concept of dissociation.

An evaluation of nonclinical dissociation utilizing a virtual environment shows enhanced working memory and attention.

PubMed

Saidel-Goley, Isaac N; Albiero, Erin E; Flannery, Kathleen A

2012-02-01

Dissociation is a mental process resulting in the disruption of memory, perception, and sometimes identity. At a nonclinical level, only mild dissociative experiences occur. The nature of nonclinical dissociation is disputed in the literature, with some asserting that it is a beneficial information processing style and others positing that it is a psychopathological phenomenon. The purpose of this study was to further the understanding of nonclinical dissociation with respect to memory and attention, by including a more ecologically valid virtual reality (VR) memory task along with standard neuropsychological tasks. Forty-five undergraduate students from a small liberal arts college in the northeast participated for course credit. The participants completed a battery of tasks including two standard memory tasks, a standard attention task, and an experimental VR memory task; the VR task included immersion in a virtual apartment, followed by incidental object-location recall for objects in the virtual apartment. Support for the theoretical model portraying nonclinical dissociation as a beneficial information processing style was found in this study. Dissociation scores were positively correlated with working memory scores and attentional processing scores on the standard neuropsychological tasks. In terms of the VR task, dissociation scores were positively correlated with more false positive memories that could be the result of a tendency of nonclinical highly dissociative individuals to create more elaborative schemas. This study also demonstrates that VR paradigms add to the prediction of cognitive functioning in testing protocols using standard neuropsychological tests, while simultaneously increasing ecological validity.

Separating Item and Order Information through Process Dissociation

ERIC Educational Resources Information Center

Nairne, James S.; Kelley, Matthew R.

2004-01-01

In the present paper, we develop and apply a technique, based on the logic of process dissociation, for obtaining numerical estimates of item and order information. Certain variables, such as phonological similarity, are widely believed to produce dissociative effects on item and order retention. However, such beliefs rest on the questionable…

Rate coefficients for dissociative attachment and resonant electron-impact dissociation involving vibrationally excited O{sub 2} molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laporta, V.; Celiberto, R.; Tennyson, J.

Rate coefficients for dissociative electron attachment and electron-impact dissociation processes, involving vibrationally excited molecular oxygen, are presented. Analytical fits of the calculated numerical data, useful in the applications, are also provided.

Hydrogen dissociation in the deposition of GaN films with ECR-PECVD process

NASA Astrophysics Data System (ADS)

Fu, S. L.; Wang, C. A.; Ding, L. C.; Qin, Y. X.

2018-05-01

The hydrogen dissociation and its effect on the GaN film growth in the ECR-PECVD process are investigated in this paper. We use N2 and trimethylgallium (TMG) as N and Ga sources respectively in the ECR- PECVD process. The results show that the rate of hydrogen dissociation increases with the microwave power and it becomes higher at high microwave power (> 500 W). However, this population increase of the H species dissociated from the TMG gas in ECR plasma is not enough to change the growth condition from Ga-rich to N-rich.

Diffractive dijet production in p̄p collisions at √s=1.96 TeV

DOE PAGES

Aaltonen, T.; Albrow, M.; Álvarez González, B.; ...

2012-08-17

We report on a study of diffractive dijet production in p̄p collisions at s√=1.96 TeV using the CDF II detector at the Fermilab Tevatron p̄p collider. A data sample from 310 pb⁻¹ of integrated luminosity collected by triggering on a high transverse energy jet, EjetT, in coincidence with a recoil antiproton detected in a Roman pot spectrometer is used to measure the ratio of single-diffractive to inclusive-dijet event rates as a function of x p̄ of the interacting parton in the antiproton, the Bjorken-x, x p̄ Bj, and a Q²≈(E jet T)² in the ranges 10⁻³p̄ Bj<10⁻¹ and 10²p̄<0.09 andmore » a four-momentum transfer squared t p̄>-4 GeV². The t p̄ dependence is measured as a function of Q² and x p̄ Bj and compared with that of inclusive single diffraction dissociation. We find weak x p̄ Bj and Q² dependencies in the ratio of single diffractive to inclusive event rates, and no significant Q² dependence in the diffractive t p̄ distributions.« less

Dissociative symptoms and dissociative disorder comorbidity in patients with obsessive-compulsive disorder.

PubMed

Belli, Hasan; Ural, Cenk; Vardar, Melek Kanarya; Yesılyurt, Sema; Oncu, Fatıh

2012-10-01

The present study attempted to assess the dissociative symptoms and overall dissociative disorder comorbidity in patients with obsessive-compulsive disorder (OCD). In addition, we examined the relationship between the severity of obsessive-compulsive symptoms and dissociative symptoms. All patients admitted for the first time to the psychiatric outpatient unit were included in the study. Seventy-eight patients had been diagnosed as having OCD during the 2-year study period. Patients had to meet the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for OCD. Most (76.9%; n = 60) of the patients were female, and 23.1% (n = 18) of the patients were male. Dissociation Questionnaire was used to measure dissociative symptoms. The Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Dissociative Disorders interviews and Yale-Brown Obsessive Compulsive Checklist and Severity Scale were used. Eleven (14%) of the patients with OCD had comorbid dissociative disorder. The most prevalent disorder in our study was dissociative depersonalization disorder. Dissociative amnesia and dissociative identity disorder were common as well. The mean Yale-Brown score was 23.37 ± 7.27 points. Dissociation Questionnaire scores were between 0.40 and 3.87 points, and the mean was 2.23 ± 0.76 points. There was a statistically significant positive correlation between Yale-Brown points and Dissociation Questionnaire points. We conclude that dissociative symptoms among patients with OCD should alert clinicians for the presence of a chronic and complex dissociative disorder. Clinicians may overlook an underlying dissociative process in patients who have severe symptoms of OCD. However, a lack of adequate response to cognitive-behavioral and drug therapy may be a consequence of dissociative process. Copyright © 2012 Elsevier Inc. All rights reserved.

Analysis of Memory Formation during General Anesthesia (Propofol/Remifentanil) for Elective Surgery Using the Process-dissociation Procedure.

PubMed

Hadzidiakos, Daniel; Horn, Nadja; Degener, Roland; Buchner, Axel; Rehberg, Benno

2009-08-01

There have been reports of memory formation during general anesthesia. The process-dissociation procedure has been used to determine if these are controlled (explicit/conscious) or automatic (implicit/unconscious) memories. This study used the process-dissociation procedure with the original measurement model and one which corrected for guessing to determine if more accurate results were obtained in this setting. A total of 160 patients scheduled for elective surgery were enrolled. Memory for words presented during propofol and remifentanil general anesthesia was tested postoperatively by using a word-stem completion task in a process-dissociation procedure. To assign possible memory effects to different levels of anesthetic depth, the authors measured depth of anesthesia using the BIS XP monitor (Aspect Medical Systems, Norwood, MA). Word-stem completion performance showed no evidence of memory for intraoperatively presented words. Nevertheless, an evaluation of these data using the original measurement model for process-dissociation data suggested an evidence of controlled (C = 0.05; 95% confidence interval [CI] 0.02-0.08) and automatic (A = 0.11; 95% CI 0.09-0.12) memory processes (P < 0.01). However, when the data were evaluated with an extended measurement model taking base rates into account adequately, no evidence for controlled (C = 0.00; 95% CI -0.04 to 0.04) or automatic (A = 0.00; 95% CI -0.02 to 0.02) memory processes was obtained. The authors report and discuss parallel findings for published data sets that were generated by using the process-dissociation procedure. Patients had no memories for auditory information presented during propofol/remifentanil anesthesia after midazolam premedication. The use of the process-dissociation procedure with the original measurement model erroneously detected memories, whereas the extended model, corrected for guessing, correctly revealed no memory.

Cognitive Processes, Trauma, and Dissociation--Misconceptions and Misrepresentations: Reply to Bremner (2010)

ERIC Educational Resources Information Center

Giesbrecht, Timo; Lynn, Steven J.; Lilienfeld, Scott O.; Merckelbach, Harald

2010-01-01

In a recent review (Giesbrecht, Lynn, Lilienfeld, & Merckelbach, 2008), we critically evaluated the research literature on cognitive processes in dissociation. In a comment, Bremner (2010) has voiced reservations about our contention that evidence for the causal role of trauma in dissociation is limited. In this reply, we argue that Bremner's…

Dissociation and Association of the Embodied Representation of Tool-Use Verbs and Hand Verbs: An fMRI Study

ERIC Educational Resources Information Center

Yang, Jie; Shu, Hua; Bi, Yanchao; Liu, Youyi; Wang, Xiaoyi

2011-01-01

Embodied semantic theories suppose that representation of word meaning and actual sensory-motor processing are implemented in overlapping systems. According to this view, association and dissociation of different word meaning should correspond to dissociation and association of the described sensory-motor processing. Previous studies demonstrate…

Dissociative Experience and Cultural Neuroscience: Narrative, Metaphor and Mechanism

PubMed Central

Kirmayer, Laurence J.

2016-01-01

Approaches to trance and possession in anthropology have tended to use outmoded models drawn from psychodynamic theory or treated such dissociative phenomena as purely discursive processes of attributing action and experience to agencies other than the self. Within psychology and psychiatry, understanding of dissociative disorders has been hindered by polemical “either/or” arguments: either dissociative disorders are real, spontaneous alterations in brain states that reflect basic neurobiological phenomena, or they are imaginary, socially constructed role performances dictated by interpersonal expectations, power dynamics and cultural scripts. In this paper, we outline an approach to dissociative phenomena, including trance, possession and spiritual and healing practices, that integrates the neuropsychological notions of underlying mechanism with sociocultural processes of the narrative construction and social presentation of the self. This integrative model, grounded in a cultural neuroscience, can advance ethnographic studies of dissociation and inform clinical approaches to dissociation through careful consideration of the impact of social context. PMID:18213511

Dissociative experience and cultural neuroscience: narrative, metaphor and mechanism.

PubMed

Seligman, Rebecca; Kirmayer, Laurence J

2008-03-01

Approaches to trance and possession in anthropology have tended to use outmoded models drawn from psychodynamic theory or treated such dissociative phenomena as purely discursive processes of attributing action and experience to agencies other than the self. Within psychology and psychiatry, understanding of dissociative disorders has been hindered by polemical "either/or" arguments: either dissociative disorders are real, spontaneous alterations in brain states that reflect basic neurobiological phenomena, or they are imaginary, socially constructed role performances dictated by interpersonal expectations, power dynamics and cultural scripts. In this paper, we outline an approach to dissociative phenomena, including trance, possession and spiritual and healing practices, that integrates the neuropsychological notions of underlying mechanism with sociocultural processes of the narrative construction and social presentation of the self. This integrative model, grounded in a cultural neuroscience, can advance ethnographic studies of dissociation and inform clinical approaches to dissociation through careful consideration of the impact of social context.

Dissociation of doubly charged clusters of lithium acetate: Asymmetric fission and breakdown of the liquid drop model: Dissociation of doubly charged clusters of lithium acetate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shukla, Anil

2016-06-08

Unimolecular and collision-induced dissociation of doubly charged lithium acetate clusters, (CH3COOLi)nLi22+, demonstrated that Coulomb fission via charge separation is the dominant dissociation process with no contribution from the neutral evaporation processes for all such ions from the critical limit to larger cluster ions, although latter process have normally been observed in all earlier studies. These results are clearly in disagreement with the Rayleigh’s liquid drop model that has been used successfully to predict the critical size and explain the fragmentation behavior of multiply charged clusters.

The production of CO(+) (B2Sigma +) from dissociative photoionization excitation of CO2

NASA Technical Reports Server (NTRS)

Wu, C. Y. R.; Judge, D. L.

1986-01-01

The dissociative photoionization excitation process in CO2 is studied. In contrast to previous studies, attention is focused on the vibrational and rotational levels produced in fragment ions, partial cross-section measurements for producing such fragment ions in a specific quantum state, and the mechanisms that govern the dissociative ionization excitation processes. The partial fluorescence cross section for the production of CO(+) (B2Sigma +) from CO2 over a wide wavelength range was measured. It is concluded that the production of the CO(+) (B2Sigma +) fragment near the threshold is through a direct dissociative photoionization process.

Observation of a J(PC)=1-+ exotic resonance in diffractive dissociation of 190   GeV/c π- into π- π- π+.

PubMed

Alekseev, M G; Alexakhin, V Yu; Alexandrov, Yu; Alexeev, G D; Amoroso, A; Austregesilo, A; Badełek, B; Balestra, F; Ball, J; Barth, J; Baum, G; Bedfer, Y; Bernhard, J; Bertini, R; Bettinelli, M; Birsa, R; Bisplinghoff, J; Bordalo, P; Bradamante, F; Bravar, A; Bressan, A; Brona, G; Burtin, E; Bussa, M P; Chapiro, A; Chiosso, M; Chung, S U; Cicuttin, A; Colantoni, M; Crespo, M L; Dalla Torre, S; Dafni, T; Das, S; Dasgupta, S S; Denisov, O Yu; Dhara, L; Diaz, V; Dinkelbach, A M; Donskov, S V; Doshita, N; Duic, V; Dünnweber, W; Efremov, A; El Alaoui, A; Eversheim, P D; Eyrich, W; Faessler, M; Ferrero, A; Finger, M; Finger, M; Fischer, H; Franco, C; Friedrich, J M; Garfagnini, R; Gautheron, F; Gavrichtchouk, O P; Gazda, R; Gerassimov, S; Geyer, R; Giorgi, M; Gobbo, B; Goertz, S; Grabmüller, S; Grajek, O A; Grasso, A; Grube, B; Gushterski, R; Guskov, A; Haas, F; von Harrach, D; Hasegawa, T; Heckmann, J; Heinsius, F H; Hermann, R; Herrmann, F; Hess, C; Hinterberger, F; Horikawa, N; Höppner, Ch; d'Hose, N; Ilgner, C; Ishimoto, S; Ivanov, O; Ivanshin, Yu; Iwata, T; Jahn, R; Jasinski, P; Jegou, G; Joosten, R; Kabuss, E; Kang, D; Ketzer, B; Khaustov, G V; Khokhlov, Yu A; Kisselev, Yu; Klein, F; Klimaszewski, K; Koblitz, S; Koivuniemi, J H; Kolosov, V N; Komissarov, E V; Kondo, K; Königsmann, K; Konopka, R; Konorov, I; Konstantinov, V F; Korzenev, A; Kotzinian, A M; Kouznetsov, O; Kowalik, K; Krämer, M; Kral, A; Kroumchtein, Z V; Kuhn, R; Kunne, F; Kurek, K; Lauser, L; Le Goff, J M; Lednev, A A; Lehmann, A; Levorato, S; Lichtenstadt, J; Liska, T; Maggiora, A; Maggiora, M; Magnon, A; Mallot, G K; Mann, A; Marchand, C; Marroncle, J; Martin, A; Marzec, J; Massmann, F; Matsuda, T; Maximov, A N; Meyer, W; Michigami, T; Mikhailov, Yu V; Moinester, M A; Mutter, A; Nagaytsev, A; Nagel, T; Nassalski, J; Negrini, T; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Olshevsky, A G; Ostrick, M; Padee, A; Panknin, R; Panzieri, D; Parsamyan, B; Paul, S; Pawlukiewicz-Kaminska, B; Perevalova, E; Pesaro, G; Peshekhonov, D V; Piragino, G; Platchkov, S; Pochodzalla, J; Polak, J; Polyakov, V A; Pontecorvo, G; Pretz, J; Quintans, C; Rajotte, J-F; Ramos, S; Rapatsky, V; Reicherz, G; Reggiani, D; Richter, A; Robinet, F; Rocco, E; Rondio, E; Ryabchikov, D I; Samoylenko, V D; Sandacz, A; Santos, H; Sapozhnikov, M G; Sarkar, S; Savin, I A; Sbrizzai, G; Schiavon, P; Schill, C; Schlüter, T; Schmitt, L; Schopferer, S; Schröder, W; Shevchenko, O Yu; Siebert, H-W; Silva, L; Sinha, L; Sissakian, A N; Slunecka, M; Smirnov, G I; Sosio, S; Sozzi, F; Srnka, A; Stolarski, M; Sulc, M; Sulej, R; Takekawa, S; Tessaro, S; Tessarotto, F; Teufel, A; Tkatchev, L G; Uhl, S; Uman, I; Venugopal, G; Virius, M; Vlassov, N V; Vossen, A; Weitzel, Q; Windmolders, R; Wiślicki, W; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M; Zhao, J; Zhuravlev, N; Zvyagin, A

2010-06-18

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1  GeV2/c2. The well-known resonances a1(1260), a2(1320), and π2(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC)=1-+ at 1.66  GeV/c2 decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC)=2-+ and 1++ waves. From a mass-dependent fit a resonance mass of (1660±10(-64)(+0))  MeV/c2 and a width of (269±21(-64)(+42))  MeV/c2 are deduced, with an intensity of (1.7±0.2)% of the total intensity.

Water dissociation on Mn(1×1)/Ag(100)

DOE PAGES

Arble, Chris; Tong, Xiao; Giordano, Livia; ...

2016-08-19

In this work we utilize experimental and simulation techniques to examine the molecular level interaction of water with a MnO(1×1) thin film deposited onto Ag(100). The formation of MnO(1×1)/Ag(100) was characterized by low energy electron diffraction and scanning tunneling microscopy. Density functional theory (DFT) shows MnO(1×1) is thermodynamically more stable than MnO(2×1) by –0.4 eV per MnO. Upon exposure to 2.5 Torr water vapor at room temperature, X-ray photoemission spectroscopy results show extensive surface hydroxylation attributed to reactivity at MnO(1×1) terrace sites. DFT calculations of a water monomer on MnO(1×1)/Ag(100) show the dissociated form is energetically more favorable than molecularmore » adsorption, with a hydroxylation activation barrier 0.4 eV per H 2O. Lastly, these results are discussed and contrasted with previous studies of MgO/Ag(100) which show a stark difference in behavior for water dissociation.« less

Theoretical study on the cooperative exciton dissociation process based on dimensional and hot charge-transfer state effects in an organic photocell

NASA Astrophysics Data System (ADS)

Shimazaki, Tomomi; Nakajima, Takahito

2016-06-01

This paper discusses the exciton dissociation process at the donor-acceptor interface in organic photocells. In our previous study, we introduced a local temperature to handle the hot charge-transfer (CT) state and calculated the exciton dissociation probability based on the 1D organic semiconductor model [T. Shimazaki and T. Nakajima, Phys. Chem. Chem. Phys. 17, 12538 (2015)]. Although the hot CT state plays an essential role in exciton dissociations, the probabilities calculated are not high enough to efficiently separate bound electron-hole pairs. This paper focuses on the dimensional (entropy) effect together with the hot CT state effect and shows that cooperative behavior between both effects can improve the exciton dissociation process. In addition, we discuss cooperative effects with site-disorders and external-electric-fields.

True and false recall and dissociation among maltreated children: the role of self-schema.

PubMed

Valentino, Kristin; Cicchetti, Dante; Rogosch, Fred A; Toth, Sheree L

2008-01-01

The current investigation addresses the manner through which trauma affects basic memory and self-system processes. True and false recall for self-referent stimuli were assessed in conjunction with dissociative symptomatology among abused (N=76), neglected (N=92), and nonmaltreated (N=116) school-aged children. Abused, neglected, and nonmaltreated children did not differ in the level of processing self-schema effect or in the occurrence and frequency of false recall. Rather, differences in the affective valence of false recall emerged as a function of maltreatment subtype and age. Regarding dissociation, the abused children displayed higher levels of dissociative symptomatology than did the nonmaltreated children. Although abused, neglected, and nonmaltreated children did not exhibit differences in the valence of their self-schemas, positive and negative self-schemas were related to self-integration differently among the subgroups of maltreatment. Negative self-schemas were associated with increased dissociation among the abused children, whereas positive self-schemas were related to increased dissociation for the neglected children. Thus, positive self-schemas displayed by the younger neglected children were related to higher dissociation, suggestive of defensive self-processing. Implications for clinical intervention are underscored.

Theory of time-resolved x-ray photoelectron diffraction from transient conformational molecules

NASA Astrophysics Data System (ADS)

Tsuru, Shota; Sako, Tokuei; Fujikawa, Takashi; Yagishita, Akira

2017-04-01

We formulate x-ray photoelectron diffraction (XPD) from molecules undergoing photochemical reactions induced by optical laser pulses, and then apply the formula to the simulation of time-dependent XPD profiles from both dissociating I2 molecules and bending C S2 molecules. The dependence of nuclear wave-packet motions on the intensity and shape of the optical laser pulses is examined. As a result, the XPD simulations based on such nuclear wave-packet calculations are observed to exhibit characteristic features, which are compared with the XPD profiles due to classical trajectories of nuclear motions. The present study provides a methodology toward creating "molecular movies" of ultrafast photochemical reactions by means of femtosecond XPD with x-ray free-electron lasers.

State selectivity and dynamics in dissociative electron attachment to CF₃I revealed through velocity slice imaging.

PubMed

Ómarsson, Frímann H; Mason, Nigel J; Krishnakumar, E; Ingólfsson, Oddur

2014-11-03

In light of its substantially more environmentally friendly nature, CF3I is currently being considered as a replacement for the highly potent global-warming gas CF4, which is used extensively in plasma processing. In this context, we have studied the electron-driven dissociation of CF3I to form CF3(-) and I, and we compare this process to the corresponding photolysis channel. By using the velocity slice imaging (VSI) technique we can visualize the complete dynamics of this process and show that electron-driven dissociation proceeds from the same initial parent state as the corresponding photolysis process. However, in contrast to photolysis, which leads nearly exclusively to the (2)P(1/2) excited state of iodine, electron-induced dissociation leads predominantly to the (2)P(3/2) ground state. We believe that the changed spin state of the negative ion allows an adiabatic dissociation through a conical intersection, whereas this path is efficiently repressed by a required spin flip in the photolysis process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Psychiatric symptoms and dissociation in conversion, somatization and dissociative disorders.

PubMed

Espirito-Santo, Helena; Pio-Abreu, Jose Luis

2009-03-01

Conversion, dissociation and somatization are historically related in the long established concept of hysteria. Somewhere along the way they were separated due to the Cartesian dualistic view. The aim of the present study was to compare these pathologies and investigate whether symptoms of these pathologies overlap in their clinical appearance in a Portuguese sample. Twenty-six patients with conversion disorder, 38 with dissociative disorders, 40 with somatization disorder, and a comparison group of 46 patients having other psychiatric disorders answered questions about dissociation (Dissociative Experiences Scale), somatoform dissociation (Somatoform Dissociation Questionnaire), and psychopathological symptoms (Brief Symptom Inventory). Dissociative and somatoform symptoms were significantly more frequent in dissociative and conversion disorder than in somatization disorder and controls. There were no significant differences between dissociative and conversion patients. Conversion disorder is closely related to dissociative disorders. These results support the ICD-10 categorization of conversion disorder among dissociative disorders and the hypothesis of analogous psychopathological processes in conversion and dissociative disorders versus somatization disorder.

Trauma-Related Dissociation Is Linked With Maladaptive Personality Functioning

PubMed Central

Granieri, Antonella; Guglielmucci, Fanny; Costanzo, Antonino; Caretti, Vincenzo; Schimmenti, Adriano

2018-01-01

Background: Extensive research has demonstrated the positive associations among the exposure to traumatic experiences, the levels of dissociation, and the severity of psychiatric symptoms in adults. However, it has been hypothesized in clinical literature that an excessive activation of the dissociative processes following multiple traumatic experiences may jeopardize the psychological and behavioral functioning of the individuals, fostering higher levels of maladaptive personality functioning. Methods: The study involved 322 adult volunteers from Italy. Participants completed measures on traumatic experiences, dissociation, and maladaptive personality traits. Results: The number of traumatic experiences reported by participants were positively associated with dissociation scores and maladaptive personality scores. Mediation analyses showed that dissociation acted as a partial mediator in the relationship between traumatic experiences and overall maladaptive personality functioning. Regression curve analyses showed that the positive association between maladaptive personality functioning and dissociation was stronger among participants with higher exposure to traumatic experiences. Conclusion: Exposure to multiple traumatic experiences may increase the risk for an excessive activation of the dissociative processes, which in turn may generate severe impairments in multiple domains of personality functioning. PMID:29887807

Theoretical study on the cooperative exciton dissociation process based on dimensional and hot charge-transfer state effects in an organic photocell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shimazaki, Tomomi; Nakajima, Takahito

2016-06-21

This paper discusses the exciton dissociation process at the donor–acceptor interface in organic photocells. In our previous study, we introduced a local temperature to handle the hot charge-transfer (CT) state and calculated the exciton dissociation probability based on the 1D organic semiconductor model [T. Shimazaki and T. Nakajima, Phys. Chem. Chem. Phys. 17, 12538 (2015)]. Although the hot CT state plays an essential role in exciton dissociations, the probabilities calculated are not high enough to efficiently separate bound electron–hole pairs. This paper focuses on the dimensional (entropy) effect together with the hot CT state effect and shows that cooperative behaviormore » between both effects can improve the exciton dissociation process. In addition, we discuss cooperative effects with site-disorders and external-electric-fields.« less

Relations between childhood traumatic experiences, dissociation, and cognitive models in obsessive compulsive disorder.

PubMed

Selvi, Yavuz; Besiroglu, Lutfullah; Aydin, Adem; Gulec, Mustafa; Atli, Abdullah; Boysan, Murat; Celik, Cihat

2012-03-01

Previous studies have indicated that obsessive compulsive disorder (OCD) is associated with childhood traumatic experiences and higher levels of dissociation. Dissociative tendency may arise when individual attempt to incorporate adverse experiences into cognitive schema. We investigated the possible links among childhood trauma, dissociation, and cognitive processes. We evaluated 95 patients with OCD using the Beck Depression Inventory (BDI), Thought-Action Fusion Scale (TAFS), Metacognitions Questionnaire (MCQ-30), White Bear Suppression Inventory (WBSI), Dissociative Experiences Scale (DES), and Childhood Trauma Questionnaire (CTQ-28). The CTQ-28 total scores were not associated with Y-BOCS total, Y-BOCS insight, BDI, TAFS, MCQ-30, and WBSI scores. The TAFS Total, MCQ-30, WBSI, and BDI scores were significantly associated with DES scores. Regression analysis revealed that MCQ-30 and WBSI scores significantly predicted the DES scores. These results suggest that in spite of pathological connotation of dissociative experiences, dissociation may primarily constitute a cognitive trait which is strongly associated with cognitive processes.

Dissociative Ionization of Benzene by Electron Impact

NASA Technical Reports Server (NTRS)

Huo, Winifred; Dateo, Christopher; Kwak, Dochan (Technical Monitor)

2002-01-01

We report a theoretical study of the dissociative ionization (DI) of benzene from the low-lying ionization channels. Our approach makes use of the fact that electron motion is much faster than nuclear motion and DI is treated as a two-step process. The first step is electron-impact ionization resulting in an ion with the same nuclear geometry as the neutral molecule. In the second step the nuclei relax from the initial geometry and undergo unimolecular dissociation. For the ionization process we use the improved binary-encounter dipole (iBED) model. For the unimolecular dissociation step, we study the steepest descent reaction path to the minimum of the ion potential energy surface. The path is used to analyze the probability of unimolecular dissociation and to determine the product distributions. Our analysis of the dissociation products and the thresholds of the productions are compared with the result dissociative photoionization measurements of Feng et al. The partial oscillator strengths from Feng et al. are then used in the iBED cross section calculations.

Distinct dissociation kinetics between ion pairs: Solvent-coordinate free-energy landscape analysis.

PubMed

Yonetani, Yoshiteru

2015-07-28

Different ion pairs exhibit different dissociation kinetics; however, while the nature of this process is vital for understanding various molecular systems, the underlying mechanism remains unclear. In this study, to examine the origin of different kinetic rate constants for this process, molecular dynamics simulations were conducted for LiCl, NaCl, KCl, and CsCl in water. The results showed substantial differences in dissociation rate constant, following the trend kLiCl < kNaCl < kKCl < kCsCl. Analysis of the free-energy landscape with a solvent reaction coordinate and subsequent rate component analysis showed that the differences in these rate constants arose predominantly from the variation in solvent-state distribution between the ion pairs. The formation of a water-bridging configuration, in which the water molecule binds to an anion and a cation simultaneously, was identified as a key step in this process: water-bridge formation lowers the related dissociation free-energy barrier, thereby increasing the probability of ion-pair dissociation. Consequently, a higher probability of water-bridge formation leads to a higher ion-pair dissociation rate.

A study of increasing radical density and etch rate using remote plasma generator system

NASA Astrophysics Data System (ADS)

Lee, Jaewon; Kim, Kyunghyun; Cho, Sung-Won; Chung, Chin-Wook

2013-09-01

To improve radical density without changing electron temperature, remote plasma generator (RPG) is applied. Multistep dissociation of the polyatomic molecule was performed using RPG system. RPG is installed to inductively coupled type processing reactor; electrons, positive ions, radicals and polyatomic molecule generated in RPG and they diffused to processing reactor. The processing reactor dissociates the polyatomic molecules with inductively coupled power. The polyatomic molecules are dissociated by the processing reactor that is operated by inductively coupled power. Therefore, the multistep dissociation system generates more radicals than single-step system. The RPG was composed with two cylinder type inductively coupled plasma (ICP) using 400 kHz RF power and nitrogen gas. The processing reactor composed with two turn antenna with 13.56 MHz RF power. Plasma density, electron temperature and radical density were measured with electrical probe and optical methods.

Psychophysiology of dissociated consciousness.

PubMed

Bob, Petr

2014-01-01

Recent study of consciousness provides an evidence that there is a limit of consciousness, which presents a barrier between conscious and unconscious processes. This barrier likely is specifically manifested as a disturbance of neural mechanisms of consciousness that through distributed brain processing, attentional mechanisms and memory processes enable to constitute integrative conscious experience. According to recent findings a level of conscious integration may change during certain conditions related to experimental cognitive manipulations, hypnosis, or stressful experiences that can lead to dissociation of consciousness. In psychopathological research the term dissociation was proposed by Pierre Janet for explanation of processes related to splitting of consciousness due to traumatic events or during hypnosis. According to several recent findings dissociation of consciousness likely is related to deficits in global distribution of information and may lead to heightened levels of "neural complexity" that reflects brain integration or differentiation based on numbers of independent neural processes in the brain that may be specifically related to various mental disorders.

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

ERIC Educational Resources Information Center

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

2012-01-01

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

The impact of dissociation on perceptual priming and intrusions after listening to auditory narratives.

PubMed

Dorahy, Martin J; Peck, Rowan K; Huntjens, Rafaele J C

2016-01-01

This study investigates the causal role of dissociation in intrusive memory development and possible underlying aberrant memory processes (e.g., increased perceptual priming). Using an audio-only adaption of the trauma film paradigm, we divided 60 participants into 3 conditions and presented them with different visual tasks-mirror staring, dot staring, or neutral images. The former 2 conditions were hypothesized to induce dissociation. Postaudio, a number of factors were assessed, including state dissociation, perceptual priming and conceptual priming, as well as intrusions over 3 days. Participants in the dissociation conditions displayed an increase in perceptual priming compared to those in the control condition and reported more distressing intrusions. No differences were found in conceptual priming and the overall number of intrusions between conditions. Findings contribute to the growing knowledge on the impact of dissociation and cognitive processing in the etiology of posttraumatic stress disorder intrusions.

Ordinal Process Dissociation and the Measurement of Automatic and Controlled Processes

ERIC Educational Resources Information Center

Hirshman, Elliot

2004-01-01

The process-dissociation equations (L. Jacoby, 1991) have been applied to results from inclusion and exclusion tasks to derive quantitative estimates of the influence of controlled and automatic processes on memory. This research has provoked controversies (e.g., T. Curran & D. Hintzman, 1995) regarding the validity of specific assumptions…

Process Dissociation and Mixture Signal Detection Theory

ERIC Educational Resources Information Center

DeCarlo, Lawrence T.

2008-01-01

The process dissociation procedure was developed in an attempt to separate different processes involved in memory tasks. The procedure naturally lends itself to a formulation within a class of mixture signal detection models. The dual process model is shown to be a special case. The mixture signal detection model is applied to data from a widely…

Dissociation in trauma: a new definition and comparison with previous formulations.

PubMed

Nijenhuis, Ellert R S; van der Hart, Onno

2011-01-01

Amid controversy regarding the psychobiological construct of dissociation, efforts to formulate a precise definition of dissociation are rare. Some understandings of dissociation are so broad that a host of common psychobiological phenomena would qualify as dissociative. Overly narrow conceptualizations of dissociation exclude phenomena that originally, and for good reasons, have been regarded as dissociative. A common lack of conceptual distinctions between dissociation as process, organization, deficit, psychological defense, and symptom adds to the current confusion. In previous publications, we criticized many of these perspectives and proposed a detailed psychobiological theory of dissociation in trauma. However, what has remained missing is a precise definition of dissociation in trauma. This article first presents such a definition and elucidates its various components. Next the new definition is compared with several other major definitions of the concept. The strengths of the new formulation are highlighted and discussed.

Dissociation Energetics and Mechanisms of Leucine Enkephalin (M + H)+ and (2M + X)+ Ions (X = H, Li, Na, K, and Rb) Measured by Blackbody Infrared Radiative Dissociation

PubMed Central

Schnier, Paul D.; Price, William D.; Strittmatter, Eric F.; Williams, Evan R.

2005-01-01

The dissociation kinetics of protonated leucine enkephalin and its proton and alkali metal bound dimers were investigated by blackbody infrared radiative dissociation in a Fourier-transform mass spectrometer. From the temperature dependence of the unimolecular dissociation rate constants, Arrhenius activation parameters in the zero-pressure limit are obtained. Protonated leucine enkephalin dissociates to form b4 and (M−H2O)+ ions with an average activation energy (Ea) of 1.1 eV and an A factor of 1010.5 s−1. The value of the A factor indicates that these dissociation processes are rearrangements. The b4 ions subsequently dissociate to form a4 ions via a process with a relatively high activation energy (1.3 eV), but one that is entropically favored. For the cationized dimers, the thermal stability decreases with increasing cation size, consistent with a simple electrostatic interaction in these noncovalent ion–molecule complexes. The Ea and A factors are indistinguishable within experimental error with values of ~1.5 eV and 1017 s−1, respectively. Although not conclusive, results from master equation modeling indicate that all these BIRD processes, except for b4 → a4, are in the rapid energy exchange limit. In this limit, the internal energy of the precursor ion population is given by a Boltzmann distribution and information about the energetics and dynamics of the reaction are obtained directly from the measured Arrhenius parameters. PMID:16554908

[Clinical Handling of Patients with Dissociative Disorders].

PubMed

Okano, Kenichiro

2015-01-01

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

Self-referenced coherent diffraction x-ray movie of Ångstrom- and femtosecond-scale atomic motion

DOE PAGES

Glownia, J. M.; Natan, A.; Cryan, J. P.; ...

2016-10-03

Time-resolved femtosecond x-ray diffraction patterns from laser-excited molecular iodine are used to create a movie of intramolecular motion with a temporal and spatial resolution of 30 fs and 0.3 Å. This high fidelity is due to interference between the nonstationary excitation and the stationary initial charge distribution. The initial state is used as the local oscillator for heterodyne amplification of the excited charge distribution to retrieve real-space movies of atomic motion on ångstrom and femtosecond scales. This x-ray interference has not been employed to image internal motion in molecules before. In conclusion, coherent vibrational motion and dispersion, dissociation, and rotationalmore » dephasing are all clearly visible in the data, thereby demonstrating the stunning sensitivity of heterodyne methods.« less

Treatment of trauma- and abuse-related dissociative symptom disorders in children and adolescents.

PubMed

Weber, Scott

2009-02-01

Dissociation is believed to be one of the most common underlying psychological processes among children and adolescents receiving mental health treatment, but most of the dissemination of information about dissociation has occurred among psychiatrists and psychologists. Modes of treatment for dissociation as it affects children and adolescents are described. Current research and practice scholarly articles on treatment of children and adolescents for dissociation and dissociative symptom disorders were accessed and critically reviewed. Prognosis in children and adolescents can vary widely among patients and between the specific types of dissociation disorder; however, expert clinicians and researchers agree that early, intense treatment offers the greatest possibility of full recovery.

Dissociations in Processing Derivational Morphology: The Right Basal Ganglia Involvement

ERIC Educational Resources Information Center

Marangolo, Paola; Piras, Fabrizio

2008-01-01

In the neuropsychological literature, there is converging evidence for a dominant role of the left hemisphere in morphological processing. However, two right hemisphere patients were described with a clear dissociation between impaired derivational morphology and preserved inflectional processing. A recent fMRI experiment confirmed the involvement…

Tandem mass spectrometry of large biomolecule ions by blackbody infrared radiative dissociation.

PubMed

Price, W D; Schnier, P D; Williams, E R

1996-03-01

A new method for the dissociation of large ions formed by electrospray ionization is demonstrated. Ions trapped in a Fourier transform mass spectrometer at pressures below 10(-)(8) Torr are dissociated by elevating the vacuum chamber to temperatures up to 215 °C. Rate constants for dissociation are measured and found to be independent of pressure below 10(-)(7) Torr. This indicates that the ions are activated by absorption of blackbody radiation emitted from the chamber walls. Dissociation efficiencies as high as 100% are obtained. There is no apparent mass limit to this method; ions as large as ubiquitin (8.6 kDa) are readily dissociated. Thermally stable ions, such as melittin 3+ (2.8 kDa), did not dissociate at temperatures up to 200 °C. This method is highly selective for low-energy fragmentation, from which limited sequence information can be obtained. From the temperature dependence of the dissociation rate constants, Arrhenius activation energies in the low-pressure limit are obtained. The lowest energy dissociation processes for the singly and doubly protonated ions of bradykinin are loss of NH(3) and formation of the b(2)/y(7) complementary pair, with activation energies of 1.3 and 0.8 eV, respectively. No loss of NH(3) is observed for the doubly protonated ion; some loss of H(2)O occurs. These results show that charge-charge interactions not only lower the activation energy for dissociation but also can dramatically change the fragmentation, most likely through changes in the gas-phase conformation of the ion. Dissociation of ubiquitin ions produces fragmentation similar to that obtained by IRMPD and SORI-CAD. Higher charge state ions dissociate to produce y and b ions; the primary fragmentation process for low charge state ions is loss of H(2)O.

A cognitive model for multidigit number reading: Inferences from individuals with selective impairments.

PubMed

Dotan, Dror; Friedmann, Naama

2018-04-01

We propose a detailed cognitive model of multi-digit number reading. The model postulates separate processes for visual analysis of the digit string and for oral production of the verbal number. Within visual analysis, separate sub-processes encode the digit identities and the digit order, and additional sub-processes encode the number's decimal structure: its length, the positions of 0, and the way it is parsed into triplets (e.g., 314987 → 314,987). Verbal production consists of a process that generates the verbal structure of the number, and another process that retrieves the phonological forms of each number word. The verbal number structure is first encoded in a tree-like structure, similarly to syntactic trees of sentences, and then linearized to a sequence of number-word specifiers. This model is based on an investigation of the number processing abilities of seven individuals with different selective deficits in number reading. We report participants with impairment in specific sub-processes of the visual analysis of digit strings - in encoding the digit order, in encoding the number length, or in parsing the digit string to triplets. Other participants were impaired in verbal production, making errors in the number structure (shifts of digits to another decimal position, e.g., 3,040 → 30,004). Their selective deficits yielded several dissociations: first, we found a double dissociation between visual analysis deficits and verbal production deficits. Second, several dissociations were found within visual analysis: a double dissociation between errors in digit order and errors in the number length; a dissociation between order/length errors and errors in parsing the digit string into triplets; and a dissociation between the processing of different digits - impaired order encoding of the digits 2-9, without errors in the 0 position. Third, within verbal production, a dissociation was found between digit shifts and substitutions of number words. A selective deficit in any of the processes described by the model would cause difficulties in number reading, which we propose to term "dysnumeria". Copyright © 2017 Elsevier Ltd. All rights reserved.

ReaxFF Grand Canonical Monte Carlo simulation of adsorption and dissociation of oxygen on platinum (111)

NASA Astrophysics Data System (ADS)

Valentini, Paolo; Schwartzentruber, Thomas E.; Cozmuta, Ioana

2011-12-01

Atomic-level Grand Canonical Monte Carlo (GCMC) simulations equipped with a reactive force field (ReaxFF) are used to study atomic oxygen adsorption on a Pt(111) surface. The off-lattice GCMC calculations presented here rely solely on the interatomic potential and do not necessitate the pre-computation of surface adlayer structures and their interpolation. As such, they provide a predictive description of adsorbate phases. In this study, validation is obtained with experimental evidence (steric heats of adsorption and isotherms) as well as DFT-based state diagrams available in the literature. The ReaxFF computed steric heats of adsorption agree well with experimental data, and this study clearly shows that indirect dissociative adsorption of O2 on Pt(111) is an activated process at non-zero coverages, with an activation energy that monotonically increases with coverage. At a coverage of 0.25 ML, a highly ordered p(2 × 2) adlayer is found, in agreement with several low-energy electron diffraction observations. Isotherms obtained from the GCMC simulations compare qualitatively and quantitatively well with previous DFT-based state diagrams, but are in disagreement with the experimental data sets available. ReaxFF GCMC simulations at very high coverages show that O atoms prefer to bind in fcc hollow sites, at least up to 0.8 ML considered in the present work. At moderate coverages, little to no disorder appears in the Pt lattice. At high coverages, some Pt atoms markedly protrude out of the surface plane. This observation is in qualitative agreement with recent STM images of an oxygen covered Pt surface. The use of the GCMC technique based on a transferable potential is particularly valuable to produce more realistic systems (adsorbent and adsorbate) to be used in subsequent dynamical simulations (Molecular Dynamics) to address recombination reactions (via either Eley-Rideal or Langmuir-Hinshelwood mechanisms) on variously covered surfaces. By using GCMC and Molecular Dynamics simulations, the ReaxFF force field can be a valuable tool for understanding heterogeneous catalysis on a solid surface. Finally, the use of a reactive potential is a necessary requirement to investigate problems where dissociative adsorption occurs, as typical of many important catalytic processes.

Fast Nitrogen Atoms from Dissociative Excitation of N2 by Electron Impact

NASA Technical Reports Server (NTRS)

Ajello, Joseph M.; Ciocca, Marco

1996-01-01

The Doppler profiles of one of the fine structure lines of the N I (1200 A) g (sup 4)S(sup 0)-(sup 4)P multiplet and of the N II (1085 A) g (sup 3)p(sup O)-(sup 3)D multiplet have been measured. Excitation of the multiplets is produced by electron impact dissociative excitation of N2. The experimental line profiles are evaluated by fast Fourier transform (FFT) techniques and analysis of the profiles yields the kinetic energy distribution of fragments. The full width at half maximum (FWHM) of N I (1200 A) increases from 27+/-6 mA at 30 eV to 37+/-4 mA at 100 eV as the emission cross section of the dissociative ionization excitation process becomes more important relative to the dissociative excitation process. The FWHM of the N II (1085 A) line is 36+/-4 mA at 100 eV. For each multiplet the kinetic energy distribution function of each of the two fragment N atoms (ions) is much broader than thermal with a mean energy above 1.0 eV. The dissociation process with the largest cross section is predissociation and predominantly produces N atoms with kinetic energy distributions having mean energies above 0.5 eV. Dissociative processes can lead to a substantial escape flux of N I atoms from the satellites, Titan and Triton of the outer planets.

Patterns of linguistic and numerical performance in aphasia.

PubMed

Rath, Dajana; Domahs, Frank; Dressel, Katharina; Claros-Salinas, Dolores; Klein, Elise; Willmes, Klaus; Krinzinger, Helga

2015-02-04

Empirical research on the relationship between linguistic and numerical processing revealed inconsistent results for different levels of cognitive processing (e.g., lexical, semantic) as well as different stimulus materials (e.g., Arabic digits, number words, letters, non-number words). Information of dissociation patterns in aphasic patients was used in order to investigate the dissociability of linguistic and numerical processes. The aim of the present prospective study was a comprehensive, specific, and systematic investigation of relationships between linguistic and numerical processing, considering the impact of asemantic vs. semantic processing and the type of material employed (numbers compared to letters vs. words). A sample of aphasic patients (n = 60) was assessed with a battery of linguistic and numerical tasks directly comparable for their cognitive processing levels (e.g., perceptual, morpho-lexical, semantic). Mean performance differences and frequencies of (complementary) dissociations in individual patients revealed the most prominent numerical advantage for asemantic tasks when comparing the processing of numbers vs. letters, whereas the least numerical advantage was found for semantic tasks when comparing the processing of numbers vs. words. Different patient subgroups showing differential dissociation patterns were further analysed and discussed. A comprehensive model of linguistic and numerical processing should take these findings into account.

Peas, please: a case report and neuroscientific review of dissociative amnesia and fugue.

PubMed

MacDonald, Kai; MacDonald, Tina

2009-01-01

Dissociative amnesia that encompasses one's entire life and identity is a rare disorder, as is dissociative fugue. In evaluating such cases, a dichotomy is often invoked between functional and organic etiologies. However, this dichotomy suffers from both conceptual and ethical flaws. Conceptually, putative brain-based, organic etiologies for many dissociative disorders-including dissociative amnesia-exist. Ethically, such dichotomies may result in dismissive care for patients with distress-based disorders like dissociative amnesia. In support of humane, neurobiologically informed treatment of patients with dissociative amnesia, we present excerpts from 2 post-event interviews with a patient who suffered and recovered from an episode of dissociative amnesia and fugue. Following this, we review current neurobiological models of dissociative amnesia that undermine the dichotomy of functional versus organic, and suggest that the crucial distinction in such cases is between a patient's willful, conscious deceit and processes that occur without conscious intent.

Dissociation energetics and mechanisms of leucine enkephalin (M + H)+ and (2M + X)+ ions (X = H, Li, Na, K, and Rb) measured by blackbody infrared radiative dissociation.

PubMed

Schnier, P D; Price, W D; Strittmatter, E F; Williams, E R

1997-08-01

The dissociation kinetics of protonated leucine enkephalin and its proton and alkali metal bound dimers were investigated by blackbody infrared radiative dissociation in a Fourier-transform mass spectrometer. From the temperature dependence of the unimolecular dissociation rate constants, Arrhenius activation parameters in the zero-pressure limit are obtained. Protonated leucine enkephalin dissociates to form b(4) and (M-H(2)O)(+) ions with an average activation energy (E(a)) of 1.1 eV and an A factor of 10(10.5) s(-1). The value of the A factor indicates that these dissociation processes are rearrangements. The b(4) ions subsequently dissociate to form a(4) ions via a process with a relatively high activation energy (1.3 eV), but one that is entropically favored. For the cationized dimers, the thermal stability decreases with increasing cation size, consistent with a simple electrostatic interaction in these noncovalent ion-molecule complexes. The E(a) and A factors are indistinguishable within experimental error with values of approximately 1.5 eV and 10(17) s(-1), respectively. Although not conclusive, results from master equation modeling indicate that all these BIRD processes, except for b(4) --> a(4), are in the rapid energy exchange limit. In this limit, the internal energy of the precursor ion population is given by a Boltzmann distribution and information about the energetics and dynamics of the reaction are obtained directly from the measured Arrhenius parameters.

Reduced amygdala reactivity and impaired working memory during dissociation in borderline personality disorder.

PubMed

Krause-Utz, Annegret; Winter, Dorina; Schriner, Friederike; Chiu, Chui-De; Lis, Stefanie; Spinhoven, Philip; Bohus, Martin; Schmahl, Christian; Elzinga, Bernet M

2018-06-01

Affective hyper-reactivity and impaired cognitive control of emotional material are core features of borderline personality disorder (BPD). A high percentage of individuals with BPD experience stress-related dissociation, including emotional numbing and memory disruptions. So far little is known about how dissociation influences the neural processing of emotional material in the context of a working memory task in BPD. We aimed to investigate whole-brain activity and amygdala functional connectivity (FC) during an Emotional Working Memory Task (EWMT) after dissociation induction in un-medicated BPD patients compared to healthy controls (HC). Using script-driven imagery, dissociation was induced in 17 patients ('BPD_D'), while 12 patients ('BPD_N') and 18 HC were exposed to neutral scripts during fMRI. Afterwards, participants performed the EWMT with neutral vs. negative IAPS pictures vs. no distractors. Main outcome measures were behavioral performance (reaction times, errors) and whole-brain activity during the EWMT. Psychophysiological interaction analysis was used to examine amygdala connectivity during emotional distraction. BPD patients after dissociation induction showed overall WM impairments, a deactivation in bilateral amygdala, and lower activity in left cuneus, lingual gyrus, and posterior cingulate than BPD_N, along with stronger left inferior frontal gyrus activity than HC. Furthermore, reduced amygdala FC with fusiform gyrus and stronger amygdala FC with right middle/superior temporal gyrus and left inferior parietal lobule was observed in BPD_D. Findings suggest that dissociation affects reactivity to emotionally salient material and WM. Altered activity in areas associated with emotion processing, memory, and self-referential processes may contribute to dissociative states in BPD.

Childhood emotional abuse, dissociation, and suicidality among patients with drug dependency in Turkey.

PubMed

Tamar-Gurol, Defne; Sar, Vedat; Karadag, Figen; Evren, Cuneyt; Karagoz, Mustafa

2008-10-01

The aim of the present study was to determine the prevalence and correlates of dissociative disorders among patients with drug dependency. The Dissociative Experiences Scale (DES) was used to screen 104 consecutive patients at an addiction treatment center. Thirty-seven patients who had scores >or=30 were compared with 21 patients who scored <10 on the DES. Both groups were then evaluated using the Dissociative Disorders Interview Schedule and the Structured Clinical Interview for Dissociative Disorders (SCID-D). The interviewers were blind to the DES scores. Twenty-seven patients (26.0%) had a dissociative disorder according to the SCID-D. Dissociative patients were younger than the non-dissociative group. History of suicide attempt and/or childhood emotional abuse was significant predictors of a dissociative disorder. The majority (59.3%) of dissociative drug users reported that dissociative experiences had existed prior to substance use. More patients in the dissociative disorder than in the non-dissociative group stopped their treatment prematurely. A considerable proportion of drug users have a dissociative disorder, which may also interfere with treatment process. The relatively young age of this subgroup of patients and frequent reports of childhood emotional abuse underline potential preventive benefits of early intervention among adolescents with developmental trauma history and dissociative psychopathology.

The contribution of dissociative processes to the production of atomic lines in hydrogen plasmas

NASA Technical Reports Server (NTRS)

Kunc, J. A.

1985-01-01

The contribution of molecular dissociative processes to the production of atomic lines is considered for a steady-state hydrogen plasma. If the contribution of dissociative processes is dominant, a substantial simplification in plasma diagnostics can be achieved. Numerical calculations have been performed for the production of Balmer alpha, beta, and gamma lines in hydrogen plasmas with medium and large degrees of ionization (x greater than about 0.0001) and for electron temperatures of 5000-45,000 K and electron densities of 10 to the 10th to 10 to the 16th/cu cm.

Dissociation of a Dynamic Protein Complex Studied by All-Atom Molecular Simulations.

PubMed

Zhang, Liqun; Borthakur, Susmita; Buck, Matthias

2016-02-23

The process of protein complex dissociation remains to be understood at the atomic level of detail. Computers now allow microsecond timescale molecular-dynamics simulations, which make the visualization of such processes possible. Here, we investigated the dissociation process of the EphA2-SHIP2 SAM-SAM domain heterodimer complex using unrestrained all-atom molecular-dynamics simulations. Previous studies on this system have shown that alternate configurations are sampled, that their interconversion can be fast, and that the complex is dynamic by nature. Starting from different NMR-derived structures, mutants were designed to stabilize a subset of configurations by swapping ion pairs across the protein-protein interface. We focused on two mutants, K956D/D1235K and R957D/D1223R, with attenuated binding affinity compared with the wild-type proteins. In contrast to calculations on the wild-type complexes, the majority of simulations of these mutants showed protein dissociation within 2.4 μs. During the separation process, we observed domain rotation and pivoting as well as a translation and simultaneous rolling, typically to alternate and weaker binding interfaces. Several unsuccessful recapturing attempts occurred once the domains were moderately separated. An analysis of protein solvation suggests that the dissociation process correlates with a progressive loss of protein-protein contacts. Furthermore, an evaluation of internal protein dynamics using quasi-harmonic and order parameter analyses indicates that changes in protein internal motions are expected to contribute significantly to the thermodynamics of protein dissociation. Considering protein association as the reverse of the separation process, the initial role of charged/polar interactions is emphasized, followed by changes in protein and solvent dynamics. The trajectories show that protein separation does not follow a single distinct pathway, but suggest that the mechanism of dissociation is common in that it initially involves transitions to surfaces with fewer, less favorable contacts compared with those seen in the fully formed complex. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Dissociation in hysteria and hypnosis: evidence from cognitive neuroscience.

PubMed

Bell, Vaughan; Oakley, David A; Halligan, Peter W; Deeley, Quinton

2011-03-01

Jean-Martin Charcot proposed the radical hypothesis that similar brain processes were responsible for the unexplained neurological symptoms of 'hysteria', now typically diagnosed as 'conversion disorder' or 'dissociative (conversion) disorder', and the temporary effects of hypnosis. While this idea has been largely ignored, recent cognitive neuroscience studies indicate that (i) hypnotisability traits are associated with a tendency to develop dissociative symptoms in the sensorimotor domain; (ii) dissociative symptoms can be modelled with suggestions in highly hypnotisable subjects; and (iii) hypnotic phenomena engage brain processes similar to those seen in patients with symptoms of hysteria. One clear theme to emerge from the findings is that 'symptom' presentation, whether clinically diagnosed or simulated using hypnosis, is associated with increases in prefrontal cortex activity suggesting that intervention by the executive system in both automatic and voluntary cognitive processing is common to both hysteria and hypnosis. Nevertheless, while the recent literature provides some compelling leads into the understanding of these phenomena, the field still lacks well controlled systematically designed studies to give a clear insight into the neurocognitive processes underlying dissociation in both hysteria and hypnosis. The aim of this review is to provide an agenda for future research.

Dissociative and double photoionization of CO from threshold to 90 A

NASA Technical Reports Server (NTRS)

Masuoka, T.; Samson, J. A. R.

1981-01-01

Partial cross sections for molecular photoionization (CO(+)), dissociative photoionization (C(+) and O(+)), and dissociative double photoionization (C(2+)) in CO have been measured from their thresholds to 90 A using techniques of mass spectrometry. The results are compared with data reported previously. Several peaks observed in the cross section curves for dissociated fragments are tentatively assigned by comparing with those in the photoelectron spectra reported for CO. It is concluded that the shoulder in the total absorption cross section curve between 400 and 90 A results solely from the dissociative ionization processes.

Electron-Driven Processes: From Single Collision Experiments to High-Pressure Discharge Plasmas

NASA Astrophysics Data System (ADS)

Becker, Kurt

2001-10-01

Plasmas are complex systems which consist of various groups of interacting particles (neutral atoms and molecules in their ground states and in excite states, electrons, and positive and negative ions). In principle, one needs to understand and describe all interactions between these particles in order to model the properties of the plasma and to predict its behavior. However, two-body interactions are often the only processes of relevance and only a subset of all possible collisional interactions are important. The focus of this talk is on collisional and radiative processes in low-temperature plasmas, both at low and high pressures. We will limit the discussion (i) to ionization and dissociation processes in molecular low-pressure plasmas and (ii) to collisional and radiative processes in high-pressure plasmas in rare gases and mixtures of rare gases and N2, O2, and H2. Electron-impact dissociation processes can be divided into dissociative excitation and dissociation into neutral ground-state fragments. Neutral molecular dissociation has only recently received attention from experimentalists and theorists because of the serious difficulties associated with the investigation of these processes. Collisional and radiative processes in high-pressure plasmas provide a fertile environment to the study of interactions that go beyond binary collisions involving ground-state species. Step-wise processes and three-body collisions begin to dominate the behavior of such plasmas. We will discuss examples of such processes as they relate to high-pressure rare gas discharge plasmas. Work supported by NSF, DOE, DARPA, NASA, and ABA Inc.

Enhanced reactive adsorption of hydrogen sulfide on the composites of graphene/graphite oxide with copper (hydr)oxychlorides.

PubMed

Mabayoje, Oluwaniyi; Seredych, Mykola; Bandosz, Teresa J

2012-06-27

Composites of copper (hydr)oxychlorides with graphite oxide or graphene were synthesized and used as adsorbents of hydrogen sulfide at dynamic conditions at ambient temperatures. The materials were extensively characterized before and after adsorption in order to link their performance to the surface features. X-ray diffraction, FTIR, thermal analysis, TEM, SEM/EDX, and adsorption of nitrogen were used. It was found that the composite with graphene has the most favorable surface features enhancing reactive adsorption of hydrogen sulfide. The presence of moisture in the H2S stream has a positive effect on the removal process owing to the dissociation process. H2S is retained on the surface via a direct replacement of OH groups and via acid-base reactions with the copper (hydr)oxide. Highly dispersed reduced copper species on the surface of the composite with graphene enhance activation of oxygen and cause formation of sulfites and sulfates. Higher conductivity of the graphene phase than that of graphite oxide helps in electron transfer in redox reactions.

Correlations between plasma variables and the deposition process of Si films from chlorosilanes in low pressure RF plasma of argon and hydrogen

NASA Technical Reports Server (NTRS)

Avni, R.; Carmi, U.; Grill, A.; Manory, R.; Grossman, E.

1984-01-01

The dissociation of chlorosilanes to silicon and its deposition on a solid substrate in a RF plasma of mixtures of argon and hydrogen were investigated as a function of the macrovariables of the plasma. The dissociation mechanism of chlorosilanes and HCl as well as the formation of Si in the plasma state were studied by sampling the plasma with a quadrupole mass spectrometer. Macrovariables such as pressure, net RF power input and locations in the plasma reactor strongly influence the kinetics of dissociation. The deposition process of microcrystalline silicon films and its chlorine contamination were correlated to the dissociation mechanism of chlorosilanes and HCl.

Dissociations among judgments do not reflect cognitive priority: an associative explanation of memory for frequency information in contingency learning.

PubMed

Vadillo, Miguel A; Luque, David

2013-03-01

Previous research on causal learning has usually made strong claims about the relative complexity and temporal priority of some processes over others based on evidence about dissociations between several types of judgments. In particular, it has been argued that the dissociation between causal judgments and trial-type frequency information is incompatible with the general cognitive architecture proposed by associative models. In contrast with this view, we conduct an associative analysis of this process showing that this need not be the case. We conclude that any attempt to gain a better insight on the cognitive architecture involved in contingency learning cannot rely solely on data about these dissociations.

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

NASA Astrophysics Data System (ADS)

Kokkonen, E.; Jänkälä, K.; Patanen, M.; Cao, W.; Hrast, M.; Bučar, K.; Žitnik, M.; Huttula, M.

2018-05-01

Photon-induced fragmentation of a full set of chlorinated methanes (CH3Cl, CH2Cl2, CHCl3, CCl4) has been investigated both experimentally and computationally. Using synchrotron radiation and electron-ion coincidence measurements, the dissociation processes were studied after chlorine 2p electron excitation. Experimental evidence for CH3Cl and CH2Cl2 contains unique features suggesting that fast dissociation processes take place. By contrast, CHCl3 and CCl4 molecules do not contain the same features, hinting that they experience alternative mechanisms for dissociation and charge migration. Computational work indicates differing rates of charge movement after the core-excitation, which can be used to explain the differences observed experimentally.

Role of ultrafast dissociation in the fragmentation of chlorinated methanes.

PubMed

Kokkonen, E; Jänkälä, K; Patanen, M; Cao, W; Hrast, M; Bučar, K; Žitnik, M; Huttula, M

2018-05-07

Photon-induced fragmentation of a full set of chlorinated methanes (CH 3 Cl, CH 2 Cl 2 , CHCl 3 , CCl 4 ) has been investigated both experimentally and computationally. Using synchrotron radiation and electron-ion coincidence measurements, the dissociation processes were studied after chlorine 2p electron excitation. Experimental evidence for CH 3 Cl and CH 2 Cl 2 contains unique features suggesting that fast dissociation processes take place. By contrast, CHCl 3 and CCl 4 molecules do not contain the same features, hinting that they experience alternative mechanisms for dissociation and charge migration. Computational work indicates differing rates of charge movement after the core-excitation, which can be used to explain the differences observed experimentally.

Quantum vs Classical Mechanics for a 'Simple' Dissociation Reaction. Should They Give the Same Results?

NASA Astrophysics Data System (ADS)

Holloway, Stephen

1997-03-01

When performing molecular dynamical simulations on light systems at low energies, there is always the risk of producing data that bear no similarity to experiment. Indeed, John Barker himself was particularly anxious about treating Ar scattering from surfaces using classical mechanics where it had been shown experimentally in his own lab that diffraction occurs. In such cases, the correct procedure is probably to play the trump card "... well of course, quantum effects will modify this so that....." and retire gracefully. For our particular interests, the tables are turned in that we are interested in gas-surface dynamical studies for highly quantized systems, but would be interested to know when it is possible to use classical mechanics in order that a greater dimensionality might be treated. For molecular dissociation and scattering, it has been oft quoted that the greater the number of degrees of freedom, the more appropriate is classical mechanics, primarily because of the mass averaging over the quantized dimensions. Is this true? We have been investigating the dissociation of hydrogen molecules at surfaces and in this talk I will present quantum results for dissociation and scattering, along with a novel method for their interpretation based upon adiabatic potential energy surfaces. Comparison with classical calculations will be made and conclusions drawn. a novel method for their interpretation based upon adiabatic potential energy surfaces

Exciton-dissociation and charge-recombination processes in pentacene/C60 solar cells: theoretical insight into the impact of interface geometry.

PubMed

Yi, Yuanping; Coropceanu, Veaceslav; Brédas, Jean-Luc

2009-11-04

The exciton-dissociation and charge-recombination processes in organic solar cells based on pentacene/C(60) heterojunctions are investigated by means of quantum-mechanical calculations. The electronic couplings and the rates of exciton dissociation and charge recombination have been evaluated for several geometrical configurations of the pentacene/C(60) complex, which are relevant to bilayer and bulk heterojunctions. The results suggest that, irrespective of the actual pentacene-fullerene orientation, both pentacene-based and C(60)-based excitons are able to dissociate efficiently. Also, in the case of parallel configurations of the molecules at the pentacene/C(60) interface, the decay of the lowest charge-transfer state to the ground state is calculated to be very fast; as a result, it can compete with the dissociation process into mobile charge carriers. Since parallel configurations are expected to be found more frequently in bulk heterojunctions than in bilayer heterojunctions, the performance of pentacene/C(60) bulk-heterojunction solar cells is likely to be more affected by charge recombination than that of bilayer devices.

Thermal behaviour and microanalysis of coal subbituminus

NASA Astrophysics Data System (ADS)

Heriyanti; Prendika, W.; Ashyar, R.; Sutrisno

2018-04-01

Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) is used to study the thermal behaviour of sub-bituminous coal. The DSC experiment was performed in air atmosphere up to 125 °C at a heating rate of 25 °C min1. The DSC curve showed that the distinct transitional stages in the coal samples studied. Thermal heating temperature intervals, peak and dissociation energy of the coal samples were also determined. The XRD analysis was used to evaluate the diffraction pattern and crystal structure of the compounds in the coal sample at various temperatures (25-350 °C). The XRD analysis of various temperatures obtained compounds from the coal sample, dominated by quartz (SiO2) and corundum (Al2O3). The increase in temperature of the thermal treatment showed a better crystal formation.

Stochastic Approaches to Understanding Dissociations in Inflectional Morphology

ERIC Educational Resources Information Center

Plunkett, Kim; Bandelow, Stephan

2006-01-01

Computer modelling research has undermined the view that double dissociations in behaviour are sufficient to infer separability in the cognitive mechanisms underlying those behaviours. However, all these models employ "multi-modal" representational schemes, where functional specialisation of processing emerges from the training process.…

Using Dual-Task Methodology to Dissociate Automatic from Nonautomatic Processes Involved in Artificial Grammar Learning

ERIC Educational Resources Information Center

Hendricks, Michelle A.; Conway, Christopher M.; Kellogg, Ronald T.

2013-01-01

Previous studies have suggested that both automatic and intentional processes contribute to the learning of grammar and fragment knowledge in artificial grammar learning (AGL) tasks. To explore the relative contribution of automatic and intentional processes to knowledge gained in AGL, we utilized dual-task methodology to dissociate automatic and…

Childhood Traumatic Experiences, Dissociative Symptoms, and Dissociative Disorder Comorbidity Among Patients With Panic Disorder: A Preliminary Study.

PubMed

Ural, Cenk; Belli, Hasan; Akbudak, Mahir; Tabo, Abdulkadir

2015-01-01

This study assessed childhood trauma history, dissociative symptoms, and dissociative disorder comorbidity in patients with panic disorder (PD). A total of 92 psychotropic drug-naive patients with PD, recruited from outpatient clinics in the psychiatry department of a Turkish hospital, were involved in the study. Participants were assessed using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D), Dissociation Questionnaire, Panic and Agoraphobia Scale, Panic Disorder Severity Scale, and Childhood Trauma Questionnaire. Of the patients with PD, 18 (19%) had a comorbid dissociative disorder diagnosis on screening with the SCID-D. The most prevalent disorders were dissociative disorder not otherwise specified, dissociative amnesia, and depersonalization disorders. Patients with a high degree of dissociation symptoms and dissociative disorder comorbidity had more severe PD than those without (p < .05). All of the childhood trauma subscales used were correlated with the severity of symptoms of dissociation and PD. Among all of the subscales, the strongest relationship was with childhood emotional abuse. Logistic regression analysis showed that emotional abuse and severity of PD were independently associated with dissociative disorder. In our study, a significant proportion of the patients with PD had concurrent diagnoses of dissociative disorder. We conclude that the predominance of PD symptoms at admission should not lead the clinician to overlook the underlying dissociative process and associated traumatic experiences among these patients.

A reconsideration of the clinical work of Harold Searles.

PubMed

Benatar, May

2008-01-01

A rereading of the work of Harold Searles in light of the more contemporary paradigm of dissociation refreshes our insights into transference and countertransference phenomena with patients who rely heavily on dissociation. Searles's perspective on the dependence of the analyst (therapist) on his or her patients, the reality of patients' projections, and patients' need to cure their analyst can be helpful in resolving conundrums and impasses in the treatment of dissociative disordered patients. The reciprocity of dissociative phenomena between patients and therapists, wherein therapists must own the reality of their own dissociative processes in the therapeutic transaction, recontextualizes Searles's clinical contributions.

Elastic and inelastic photoproduction of J/ ψ mesons at HERA

NASA Astrophysics Data System (ADS)

Aid, S.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Bähr, J.; Bán, J.; Ban, Y.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bispham, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Burton, M. J.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Charlet, M.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Cocks, S.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Cousinou, M.-C.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; Davis, C. L.; Delcourt, B.; De Roeck, A.; De Wolf, E. A.; Dirkmann, M.; Dixon, P.; Di Nezza, P.; Dlugosz, W.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Fahr, A. B.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Genzel, H.; Gerhards, R.; Glazov, A.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Golec-Biernat, K.; Gonzalez-Pineiro, B.; Gorelov, I.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Griffiths, R.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hampel, M.; Haynes, W. J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herynek, I.; Hess, M. F.; Hildesheim, W.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Hoffmann, D.; Holtom, T.; Horisberger, R.; Hudgson, V. L.; Hütte, M.; Hufnagel, H.; Ibbotson, M.; Itterbeck, H.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jöhnson, L.; Johannsen, K.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kander, M.; Kant, D.; Kaschowitz, R.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kaufmann, O.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhler, T.; Köhne, J. H.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Krüner-Marquis, U.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Lacour, D.; Laforge, B.; Lander, R.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Laporte, J.-F.; Lebedev, A.; Lehner, F.; Leverenz, C.; Levonian, S.; Ley, Ch.; Lindström, G.; Lindstroem, M.; Link, J.; Linsel, F.; Lipinski, J.; List, B.; Lobo, G.; Lohmander, H.; Lomas, J. W.; Lopez, G. C.; Lubimov, V.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, G.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Merz, T.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Migliori, A.; Mikocki, S.; Milstead, D.; Moeck, J.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, D.; Müller, G.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Niggli, H.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Pawletta, H.; Peppel, E.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pope, G.; Prell, S.; Prosi, R.; Rabbertz, K.; Rädel, G.; Raupach, F.; Reimer, P.; Reinshagen, S.; Rick, H.; Riech, V.; Riedlberger, J.; Riepenhausen, F.; Riess, S.; Rizvi, E.; Robertson, S. M.; Robmann, P.; Roloff, H. E.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Sahlmann, N.; Sankey, D. P. C.; Schacht, P.; Schiek, S.; Schleif, S.; Schleper, P.; von Schlippe, W.; Schmidt, D.; Schmidt, G.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Sefkow, F.; Seidel, M.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Solochenko, V.; Soloviev, Y.; Specka, A.; Spiekermann, J.; Spielman, S.; Spitzer, H.; Squinabol, F.; Starosta, R.; Steenbock, M.; Steffen, P.; Steinberg, R.; Steiner, H.; Stella, B.; Stellberger, A.; Stier, J.; Stiewe, J.; Stöβlein, U.; Stolze, K.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Taševský, M.; Tchernyshov, V.; Tchetchelnitski, S.; Theissen, J.; Thiebaux, C.; Thompson, G.; Truöl, P.; Turnau, J.; Tutas, J.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Vandenplas, D.; Van Esch, P.; Van Mechelen, P.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Walther, A.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wünsch, E.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zimmer, M.; Zomer, F.; Zsembery, J.; Zuber, K.; zurNedden, M.; H1 Collaboration

1996-02-01

Results on J/ ψ production in ep interactions in the H1 experiment at HERA are presented. The J/ ψ mesons are produced by almost real photons ( Q2 ≈ 0) and detected via their leptonic decays. The data have been taken in 1994 and correspond to an integrated luminosity of 2.7 pb -1. The γp cross section for elastic J/ ψ production is observed to increase strongly with the center of mass energy. The cross section for diffractive J/ ψ production with proton dissociation is found to be of similar magnitude as the elastic cross section. Distributions of transverse momentum and decay angle are studied and found to be in accord with a diffractive production mechanism. For inelastic J/ ψ production the total γp cross section, the distribution of transverse momenta, and the elasticity of the J/ ψ are compared to NLO QCD calculations in a colour singlet model and agreement is found. Diffractive ψ' production has been observed and a first estimate of the ratio to J/ ψ production in the HERA energy regime is given.

Experimental Study and Mathematical Modeling of Self-Sustained Kinetic Oscillations in Catalytic Oxidation of Methane over Nickel.

PubMed

Lashina, Elena A; Kaichev, Vasily V; Saraev, Andrey A; Vinokurov, Zakhar S; Chumakova, Nataliya A; Chumakov, Gennadii A; Bukhtiyarov, Valerii I

2017-09-21

The self-sustained kinetic oscillations in the oxidation of CH 4 over Ni foil have been studied at atmospheric pressure using an X-ray diffraction technique and mass spectrometry. It has been shown that the regular oscillations appear under oxygen-deficient conditions; CO, CO 2 , H 2 , and H 2 O are detected as the products. According to in situ X-ray diffraction measurements, nickel periodically oxidizes to NiO initiating the reaction-rate oscillations. To describe the oscillations, we have proposed a five-stage mechanism of the partial oxidation of methane over Ni and a corresponding three-variable kinetic model. The mechanism considers catalytic methane decomposition, dissociative adsorption of oxygen, transformation of chemisorbed oxygen to surface nickel oxide, and reaction of adsorbed carbon and oxygen species to form CO. Analysis of the kinetic model indicates that the competition of two processes, i.e., the oxidation and the carbonization of the catalyst surface, is the driving force of the self-sustained oscillations in the oxidation of methane. We have compared this mechanism with the detailed 18-stage mechanism described previously by Lashina et al. (Kinetics and Catalysis 2012, 53, 374-383). It has been shown that both kinetic mechanisms coupled with a continuous stirred-tank reactor model describe well the oscillatory behavior in the oxidation of methane under non-isothermal conditions.

Evidence of automatic processing in sequence learning using process-dissociation

PubMed Central

Mong, Heather M.; McCabe, David P.; Clegg, Benjamin A.

2012-01-01

This paper proposes a way to apply process-dissociation to sequence learning in addition and extension to the approach used by Destrebecqz and Cleeremans (2001). Participants were trained on two sequences separated from each other by a short break. Following training, participants self-reported their knowledge of the sequences. A recognition test was then performed which required discrimination of two trained sequences, either under the instructions to call any sequence encountered in the experiment “old” (the inclusion condition), or only sequence fragments from one half of the experiment “old” (the exclusion condition). The recognition test elicited automatic and controlled process estimates using the process dissociation procedure, and suggested both processes were involved. Examining the underlying processes supporting performance may provide more information on the fundamental aspects of the implicit and explicit constructs than has been attainable through awareness testing. PMID:22679465

First-principles analysis of C2H2 molecule diffusion and its dissociation process on the ferromagnetic bcc-Fe110 surface.

PubMed

Ikeda, Minoru; Yamasaki, Takahiro; Kaneta, Chioko

2010-09-29

Using the projector-augmented plane wave method, we study diffusion and dissociation processes of C(2)H(2) molecules on the ferromagnetic bcc-Fe(110) surface and investigate the formation process of graphene created by C(2)H(2) molecules. The most stable site for C(2)H(2) on the Fe surface is a hollow site and its adsorption energy is - 3.5 eV. In order to study the diffusion process of the C(2)H(2) molecule, the barrier height energies for the C atom, C(2)-dimer and CH as well as the C(2)H(2) molecule are estimated using the nudged elastic band method. The barrier height energy for C(2)H(2) is 0.71 eV and this indicates that the C(2)H(2) diffuses easily on this FM bcc-Fe(110) surface. We further investigate the two step dissociation process of C(2)H(2) on Fe. The first step is the dissociation of C(2)H(2) into C(2)H and H, and the second step is that of C(2)H into C(2) and H. Their dissociation energies are 0.9 and 1.2 eV, respectively. These energies are relatively small compared to the dissociation energy 7.5 eV of C(2)H(2) into C(2)H and H in the vacuum. Thus, the Fe surface shows catalytic effects. We further investigate the initial formation process of graphene by increasing the coverage of C(2)H(2). The formation process of the benzene molecule on the FM bcc(110) surface is also discussed. We find that there exists a critical coverage of C(2)H(2) which characterizes the beginning of the formation of the graphene.

Pathways for Energization of Ca in Mercury's Exosphere

NASA Technical Reports Server (NTRS)

Killen, Rosemary M.

2015-01-01

We investigate the possible pathways to produce the extreme energy observed in the calcium exosphere of Mercury. Any mechanism must explain the facts that Ca in Mercury's exosphere is extremely hot, that it is seen almost exclusively on the dawnside of the planet, and that its content varies seasonally, not sporadically. Simple diatomic molecules or their clusters are considered, focusing on calcium oxides while acknowledging that Ca sulfides may also be the precursor molecules. We first discuss impact vaporization to justify the assumption that CaO and Ca-oxide clusters are expected from impacts on Mercury. Then we discuss processes by which the atomic Ca is energized to a 70,000 K gas. The processes considered are (1) electron-impact dissociation of CaO molecules, (2) spontaneous dissociation of Ca-bearing molecules following impact vaporization, (3) shock-induced dissociative ionization, (4) photodissociation and (5) sputtering. We conclude that electron-impact dissociation cannot produce the required abundance of Ca, and sputtering cannot reproduce the observed spatial and temporal variation that is measured. Spontaneous dissociation is unlikely to result in the high energy that is seen. Of the two remaining processes, shock induced dissociative ionization produces the required energy and comes close to producing the required abundance, but rates are highly dependent on the incoming velocity distribution of the impactors. Photodissociation probably can produce the required abundance of Ca, but simulations show that photodissociation cannot reproduce the observed spatial distribution.

Mechanism of reactant and product dissociation from the anthrax edema factor: a locally enhanced sampling and steered molecular dynamics study.

PubMed

Martínez, Leandro; Malliavin, Thérèse E; Blondel, Arnaud

2011-05-01

The anthrax edema factor is a toxin overproducing damaging levels of cyclic adenosine monophosphate (cAMP) and pyrophosphate (PPi) from ATP. Here, mechanisms of dissociation of ATP and products (cAMP, PPi) from the active site are studied using locally enhanced sampling (LES) and steered molecular dynamics simulations. Various substrate conformations and ionic binding modes found in crystallographic structures are considered. LES simulations show that PPi and cAMP dissociate through different solvent accessible channels, while ATP dissociation requires significant active site exposure to solvent. The ionic content of the active site directly affects the dissociation of ATP and products. Only one ion dissociates along with ATP in the two-Mg(2+) binding site, suggesting that the other ion binds EF prior to ATP association. Dissociation of reaction products cAMP and PPi is impaired by direct electrostatic interactions between products and Mg(2+) ions. This provides an explanation for the inhibitory effect of high Mg(2+) concentrations on EF enzymatic activity. Breaking of electrostatic interactions is dependent on a competitive binding of water molecules to the ions, and thus on the solvent accessibility of the active site. Consequently, product dissociation seems to be a two-step process. First, ligands are progressively solvated while preserving the most important electrostatic interactions, in a process that is dependent on the flexibility of the active site. Second, breakage of the electrostatic bonds follows, and ligands diffuse into solvent. In agreement with this mechanism, product protonation facilitates dissociation.

The dissociation and recombination rates of CH4 through the Ni(111) surface: The effect of lattice motion

NASA Astrophysics Data System (ADS)

Wang, Wenji; Zhao, Yi

2017-07-01

Methane dissociation is a prototypical system for the study of surface reaction dynamics. The dissociation and recombination rates of CH4 through the Ni(111) surface are calculated by using the quantum instanton method with an analytical potential energy surface. The Ni(111) lattice is treated rigidly, classically, and quantum mechanically so as to reveal the effect of lattice motion. The results demonstrate that it is the lateral displacements rather than the upward and downward movements of the surface nickel atoms that affect the rates a lot. Compared with the rigid lattice, the classical relaxation of the lattice can increase the rates by lowering the free energy barriers. For instance, at 300 K, the dissociation and recombination rates with the classical lattice exceed the ones with the rigid lattice by 6 and 10 orders of magnitude, respectively. Compared with the classical lattice, the quantum delocalization rather than the zero-point energy of the Ni atoms further enhances the rates by widening the reaction path. For instance, the dissociation rate with the quantum lattice is about 10 times larger than that with the classical lattice at 300 K. On the rigid lattice, due to the zero-point energy difference between CH4 and CD4, the kinetic isotope effects are larger than 1 for the dissociation process, while they are smaller than 1 for the recombination process. The increasing kinetic isotope effect with decreasing temperature demonstrates that the quantum tunneling effect is remarkable for the dissociation process.

In vitro analysis of human immunodeficiency virus particle dissociation: gag proteolytic processing influences dissociation kinetics.

PubMed

Müller, Barbara; Anders, Maria; Reinstein, Jochen

2014-01-01

Human immunodeficiency virus particles undergo a step of proteolytic maturation, in which the main structural polyprotein Gag is cleaved into its mature subunits matrix (MA), capsid (CA), nucleocapsid (NC) and p6. Gag proteolytic processing is accompanied by a dramatic structural rearrangement within the virion, which is necessary for virus infectivity and has been proposed to proceed through a sequence of dissociation and reformation of the capsid lattice. Morphological maturation appears to be tightly regulated, with sequential cleavage events and two small spacer peptides within Gag playing important roles by regulating the disassembly of the immature capsid layer and formation of the mature capsid lattice. In order to measure the influence of individual Gag domains on lattice stability, we established Förster's resonance energy transfer (FRET) reporter virions and employed rapid kinetic FRET and light scatter measurements. This approach allowed us to measure dissociation properties of HIV-1 particles assembled in eukaryotic cells containing Gag proteins in different states of proteolytic processing. While the complex dissociation behavior of the particles prevented an assignment of kinetic rate constants to individual dissociation steps, our analyses revealed characteristic differences in the dissociation properties of the MA layer dependent on the presence of additional domains. The most striking effect observed here was a pronounced stabilization of the MA-CA layer mediated by the presence of the 14 amino acid long spacer peptide SP1 at the CA C-terminus, underlining the crucial role of this peptide for the resolution of the immature particle architecture.

Posture-based processing in visual short-term memory for actions.

PubMed

Vicary, Staci A; Stevens, Catherine J

2014-01-01

Visual perception of human action involves both form and motion processing, which may rely on partially dissociable neural networks. If form and motion are dissociable during visual perception, then they may also be dissociable during their retention in visual short-term memory (VSTM). To elicit form-plus-motion and form-only processing of dance-like actions, individual action frames can be presented in the correct or incorrect order. The former appears coherent and should elicit action perception, engaging both form and motion pathways, whereas the latter appears incoherent and should elicit posture perception, engaging form pathways alone. It was hypothesized that, if form and motion are dissociable in VSTM, then recognition of static body posture should be better after viewing incoherent than after viewing coherent actions. However, as VSTM is capacity limited, posture-based encoding of actions may be ineffective with increased number of items or frames. Using a behavioural change detection task, recognition of a single test posture was significantly more likely after studying incoherent than after studying coherent stimuli. However, this effect only occurred for spans of two (but not three) items and for stimuli with five (but not nine) frames. As in perception, posture and motion are dissociable in VSTM.

Dissociation as a mediator of child abuse across generations.

PubMed

Egeland, B; Susman-Stillman, A

1996-11-01

To test the hypothesis that dissociative process is the mechanism that accounts for the transmission of maltreatment across generations, a group of mothers who were abused and maltreated their children were compared to a group of mothers who broke the cycle of abuse. Mothers who were abused and are abusing their children were rated higher on idealization, inconsistency, and escapism in their description of their childhood and they scored higher on the Dissociative Experience Scale compared to mothers who broke the cycle. Mothers who were abused and abused their children recalled the care they received as children in a fragmented and disconnected fashion whereas those who broke the cycle integrated their abusive experience into a more coherent view of self. Even after partialing out the effects of IQ, large differences were found indicating that dissociative process plays a part in the transmission of maltreatment across generations. Possible reasons why some maltreated individuals coped with the trauma by dissociating and others integrate the experience were discussed.

In-situ visual observation for the formation and dissociation of methane hydrates in porous media by magnetic resonance imaging.

PubMed

Zhao, Jiafei; Lv, Qin; Li, Yanghui; Yang, Mingjun; Liu, Weiguo; Yao, Lei; Wang, Shenglong; Zhang, Yi; Song, Yongchen

2015-05-01

In this work, magnetic resonance imaging (MRI) was employed to observe the in-situ formation and dissociation of methane hydrates in porous media. Methane hydrate was formed in a high-pressure cell with controlled temperature, and then the hydrate was dissociated by thermal injection. The process was photographed by the MRI, and the pressure was recorded. The images confirmed that the direct visual observation was achieved; these were then employed to provide detailed information of the nucleation, growth, and decomposition of the hydrate. Moreover, the saturation of methane hydrate during the dissociation was obtained from the MRI intensity data. Our results showed that the hydrate saturation initially decreased rapidly, and then slowed down; this finding is in line with predictions based only on pressure. The study clearly showed that MRI is a useful technique to investigate the process of methane hydrate formation and dissociation in porous media. Copyright © 2015 Elsevier Inc. All rights reserved.

The effects of dissociation on information processing for analogue trauma and neutral stimuli: a laboratory study.

PubMed

Olsen, Shira A; Beck, J Gayle

2012-01-01

This study investigated the effects of high and low levels of dissociation on information processing for analogue trauma and neutral stimuli. Fifty-four undergraduate females who reported high and low levels of trait dissociation were presented with two films, one depicting traumatic events, the other containing neutral material. Participants completed a divided attention task (yielding a proxy measure of attention), as well as explicit memory (free-recall) and implicit memory (word-stem completion) tasks for both films. Results indicated that the high DES group showed less attention and had poorer recall for the analogue trauma stimuli, relative to the neutral stimuli and the low DES group. These findings suggest that high levels of trait dissociation are associated with reductions in attention and memory for analogue trauma stimuli, relative to neutral stimuli and relative to low trait dissociation. Implications for the role of cognitive factors in the etiology of negative post-trauma responses are discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

Subliminal processes, dissociation and the 'I'.

PubMed

Bob, Petr

2003-06-01

The study of unconscious processes leads to the hypothesis of the limit of consciousness, which involves two main kinds of psychic activity. The first represents psychic contents which are subliminal for their low energy, the second subliminal contents which are inaccessible to consciousness because they are dissociated in the subliminal region. Dissociation is a concept introduced by Pierre Janet for splitting consciousness due to traumatic events or during hypnosis. It takes a more general form in Hilgard's neo-dissociation theory of hypnotic phenomena and also in Jung's theory of the collective unconscious. Further generalization links it to the modern findings of explicit and implicit perception, leading to a shift in dissociation from hypothesis to clinical, experimental and theoretical reality. Studies in hypnosis also point to the existence of an integrative psychic entity, that comprises the conscious 'I'. Hilgard called this the hidden observer, and his findings represent empirical confirmation of Jung's term for the Self as mirror 'I', which leads to many important consequences for self-discovery and the meaning of life.

Dissociable effects of motivation and expectancy on conflict processing: an fMRI study.

PubMed

Soutschek, Alexander; Stelzel, Christine; Paschke, Lena; Walter, Henrik; Schubert, Torsten

2015-02-01

Previous studies suggest that both motivation and task difficulty expectations activate brain regions associated with cognitive control. However, it remains an open question whether motivational and cognitive determinants of control have similar or dissociable impacts on conflict processing on a neural level. The current study tested the effects of motivation and conflict expectancy on activity in regions related to processing of the target and the distractor information. Participants performed a picture-word interference task in which we manipulated the size of performance-dependent monetary rewards (level of motivation) and the ratio of congruent to incongruent trials within a block (level of conflict expectancy). Our results suggest that motivation improves conflict processing by facilitating task-relevant stimulus processing and task difficulty expectations mainly modulate the processing of distractor information. We conclude that motivation and conflict expectancy engage dissociable control strategies during conflict resolution.

Dissociative Ionization and Product Distributions of Benzene and Pyridine by Electron Impact

NASA Technical Reports Server (NTRS)

Dateo, Christopher E.; Huo, Winifred M.; Fletcher, Graham D.

2003-01-01

We report a theoretical study of the dissociative ionization (DI) and product distributions of benzene (C6H6) and pyridine (C5H5N) from their low-lying ionization channels. Our approach makes use of the fact that electronic motion is much faster than nuclear motion allowing DI to be treated as a two-step process. The first step is the electron-impact ionization resulting in an ion with the same nuclear geometry as the neutral molecule. In the second step, the nuclei relax from the initial geometry and undergo unimolecular dissociation. For the ionization process we use the improved binary-encounter dipole (iBED) model [W.M. Huo, Phys. Rev. A64,042719-I (2001)]. For the unimolecular dissociation, we use multiconfigurational self-consistent field (MCSCF) methods to determine the steepest descent pathways to the possible product channels. More accurate methods are then used to obtain better energetics of the paths which are used to determine unimolecular dissociation probabilities and product distributions. Our analysis of the dissociation products and the thresholds of their productions for benzene are compared with the recent dissociative photoionization meausurements of benzene by Feng et al. [R. Feng, G. Cooper, C.E. Brion, J. Electron Spectrosc. Relat. Phenom. 123,211 (2002)] and the dissociative photoionization measurements of pyridine by Tixier et al. [S. Tixier, G. Cooper, R. Feng, C.E. Brion, J. Electron Spectrosc. Relat. Phenom. 123,185 (2002)] using dipole (e,e+ion) coincidence spectroscopy.

Ion/Neutral, Ion/Electron, Ion/Photon, and Ion/Ion Interactions in Tandem Mass Spectrometry: Do we need them all? Are they enough?

PubMed Central

McLuckey, Scott A.; Mentinova, Marija

2011-01-01

A range of strategies and tools has been developed to facilitate the determination of primary structures of analyte molecules of interest via tandem mass spectrometry (MS/MS). The two main factors that determine the primary structural information present in an MS/MS spectrum are the type of ion generated from the analyte molecule and the dissociation method. The ion-type subjected to dissociation is determined by the ionization method/conditions and ion transformation processes that might take place after initial gas-phase ion formation. Furthermore, the range of analyte-related ion types can be expanded via derivatization reactions prior to mass spectrometry. Dissociation methods include those that simply alter the population of internal states of the mass-selected ion (i.e., activation methods like collision-induced dissociation) as well as processes that rely on transformation of the ion-type prior to dissociation (e.g., electron capture dissociation). A variety of ionic interactions has been studied for the purpose of ion dissociation and ion transformation that include ion/neutral, ion/photon, ion/electron, and ion/ion interactions. A wide range of phenomena has been observed, many of which have been explored/developed as means for structural analysis. The techniques arising from these phenomena are discussed within the context of the elements of structure determination in tandem mass spectrometry, viz., ion-type definition and dissociation. Unique aspects of the various ion interactions are emphasized along with any barriers to widespread implementation. PMID:21472539

Weakly Bound Free Radicals in Combustion: "Prompt" Dissociation of Formyl Radicals and Its Effect on Laminar Flame Speeds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Labbe, Nicole J.; Sivaramakrishnan, Raghu; Goldsmith, C. Franklin

2016-01-07

Weakly bound free radicals have low-dissociation thresholds such that at high temperatures, timescales for dissociation and collisional relaxation become comparable, leading to significant dissociation during the vibrational-rotational relaxation process. Here we characterize this “prompt” dissociation of formyl (HCO), an important combustion radical, using direct dynamics calculations for OH + CH2O and H + CH2O (key HCO-forming reactions). For all other HCO-forming reactions, presumption of a thermal incipient HCO distribution was used to derive prompt dissociation fractions. Inclusion of these theoretically derived HCO prompt dissociation fractions into combustion kinetics models provides an additional source for H-atoms that feeds chain branching reactions.more » Simulations using these updated combustion models are therefore shown to enhance flame propagation in 1,3,5-trioxane and acetylene. The present results suggest that HCO prompt dissociation should be included when simulating flames of hydrocarbons and oxygenated molecules and that prompt dissociations of other weakly bound radicals may also impact combustion simulations« less

Predictors of expressive writing content and posttraumatic stress following a mass shooting.

PubMed

Reddy, Madhavi K; Seligowski, Antonia V; Rabenhorst, Mandy M; Orcutt, Holly K

2015-05-01

This study examined relations among experiential avoidance, state dissociation during writing, cognitive-emotional processing, and posttraumatic stress in the context of an expressive writing task among 58 undergraduate females who were students at a large midwestern university that had recently experienced a mass shooting. Experiential avoidance significantly predicted reported suppression during the writing task. Additionally, posttraumatic stress symptoms (PTSS) at the time of the writing task were significantly associated with state dissociation, suppression, and the use of positive emotion words during the writing. Finally, at the zero-order level, prospective PTSS were associated with state dissociation and suppression during the earlier writing task. However, in a full regression model, only experiential avoidance and PTSS at the time of the writing task significantly predicted prospective PTSS. Supplemental analyses suggest processes may operate differently across levels of exposure. Findings from the present study provide further support for the role of experiential avoidance, state dissociation during writing, and cognitive-emotional processing in predicting PTSS. Additionally, experiential avoidance may play an important role in how individuals use cognitive-emotional processing to narrate a traumatic event. (c) 2015 APA, all rights reserved).

Pain, dissociation and subliminal self-representations.

PubMed

Bob, Petr

2008-03-01

According to recent evidence, neurophysiological processes coupled to pain are closely related to the mechanisms of consciousness. This evidence is in accordance with findings that changes in states of consciousness during hypnosis or traumatic dissociation strongly affect conscious perception and experience of pain, and markedly influence brain functions. Past research indicates that painful experience may induce dissociated state and information about the experience may be stored or processed unconsciously. Reported findings suggest common neurophysiological mechanisms of pain and dissociation and point to a hypothesis of dissociation as a defense mechanism against psychological and physical pain that substantially influences functions of consciousness. The hypothesis is also supported by findings that information can be represented in the mind/brain without the subject's awareness. The findings of unconsciously present information suggest possible binding between conscious contents and self-functions that constitute self-representational dimensions of consciousness. The self-representation means that certain inner states of own body are interpreted as mental and somatic identity, while other bodily signals, currently not accessible to the dominant interpreter's access are dissociated and may be defined as subliminal self-representations. In conclusion, the neurophysiological aspects of consciousness and its integrative role in the therapy of painful traumatic memories are discussed.

Laser-induced dissociation processes of protonated glucose: dehydration reactions vs cross-ring dissociation

NASA Astrophysics Data System (ADS)

Dyakov, Y. A.; Kazaryan, M. A.; Golubkov, M. G.; Gubanova, D. P.; Bulychev, N. A.; Kazaryan, S. M.

2018-04-01

Studying the processes occurring in biological systems under irradiation is critically important for understanding the principles of working of biological systems. One of the main problems, which stimulate interest to the processes of photo-induced excitation and ionization of biomolecules, is the necessity of their identification by various mass spectrometry (MS) methods. While simple analysis of small molecules became a standard MS technique long time ago, recognition of large molecules, especially carbohydrates, is still a difficult problem, and requires sophisticated techniques and complicated computer analysis. Due to the large variety of substances in the samples, as far as the complexity of the processes occurring after excitation/ionization of the molecules, the recognition efficiency of MS technique in terms of carbohydrates is still not high enough. Additional theoretical and experimental analysis of ionization and dissociation processes in various kinds of polysaccharides, beginning from the simplest ones, is necessary. In our work, we extent previous theoretical and experimental studies of saccharides, and concentrate our attention to protonated glucose. In this article we paid the most attention to the cross-ring dissociation and water loss reactions due to their importance for identification of various isomers of hydrocarbon molecules (for example, distinguish α- and β-glucose).

Dissociating sensory from decision processes in human perceptual decision making.

PubMed

Mostert, Pim; Kok, Peter; de Lange, Floris P

2015-12-15

A key question within systems neuroscience is how the brain translates physical stimulation into a behavioral response: perceptual decision making. To answer this question, it is important to dissociate the neural activity underlying the encoding of sensory information from the activity underlying the subsequent temporal integration into a decision variable. Here, we adopted a decoding approach to empirically assess this dissociation in human magnetoencephalography recordings. We used a functional localizer to identify the neural signature that reflects sensory-specific processes, and subsequently traced this signature while subjects were engaged in a perceptual decision making task. Our results revealed a temporal dissociation in which sensory processing was limited to an early time window and consistent with occipital areas, whereas decision-related processing became increasingly pronounced over time, and involved parietal and frontal areas. We found that the sensory processing accurately reflected the physical stimulus, irrespective of the eventual decision. Moreover, the sensory representation was stable and maintained over time when it was required for a subsequent decision, but unstable and variable over time when it was task-irrelevant. In contrast, decision-related activity displayed long-lasting sustained components. Together, our approach dissects neuro-anatomically and functionally distinct contributions to perceptual decisions.

Dissociating sensory from decision processes in human perceptual decision making

PubMed Central

Mostert, Pim; Kok, Peter; de Lange, Floris P.

2015-01-01

A key question within systems neuroscience is how the brain translates physical stimulation into a behavioral response: perceptual decision making. To answer this question, it is important to dissociate the neural activity underlying the encoding of sensory information from the activity underlying the subsequent temporal integration into a decision variable. Here, we adopted a decoding approach to empirically assess this dissociation in human magnetoencephalography recordings. We used a functional localizer to identify the neural signature that reflects sensory-specific processes, and subsequently traced this signature while subjects were engaged in a perceptual decision making task. Our results revealed a temporal dissociation in which sensory processing was limited to an early time window and consistent with occipital areas, whereas decision-related processing became increasingly pronounced over time, and involved parietal and frontal areas. We found that the sensory processing accurately reflected the physical stimulus, irrespective of the eventual decision. Moreover, the sensory representation was stable and maintained over time when it was required for a subsequent decision, but unstable and variable over time when it was task-irrelevant. In contrast, decision-related activity displayed long-lasting sustained components. Together, our approach dissects neuro-anatomically and functionally distinct contributions to perceptual decisions. PMID:26666393

Phase diagram of the Pr-Mn-O system in composition-temperature-oxygen pressure coordinates

NASA Astrophysics Data System (ADS)

Vedmid', L. B.; Yankin, A. M.; Fedorova, O. M.; Kozin, V. M.

2016-05-01

The phase relations in the Pr-Mn-O system were studied by the static method at lowered oxygen pressure in combination with thermal analysis and high-temperature X-ray diffraction. The equilibrium oxygen pressure in dissociation of PrMn2O5 and PrMnO3 was measured, and the thermodynamic characteristics of formation of these compounds from elements were calculated. The P- T- x phase diagram of the Pr-Mn-O system was constructed in the "composition-oxygen pressure-temperature" coordinates.

Superconductivity under high pressure in the binary compound CaLi2

NASA Astrophysics Data System (ADS)

Debessai, M.; Matsuoka, T.; Hamlin, J. J.; Gangopadhyay, A. K.; Schilling, J. S.; Shimizu, K.; Ohishi, Y.

2008-12-01

Feng predicted for CaLi2 highly anomalous properties with possible superconductivity under very high pressures, including for the hcp polymorph a significant lattice bifurcation at pressures above 47 GPa. More recently, however, Feng suggested that for pressures exceeding 20 GPa CaLi2 may dissociate into elemental Ca and Li. Here we present for hcp CaLi2 measurements of the electrical resistivity and ac susceptibility to low temperatures under pressures as high as 81 GPa. Pressure-induced superconductivity is observed in the pressure range of 11-81 GPa, with Tc reaching values as high as 13 K. X-ray diffraction studies to 54 GPa at 150 K reveal that hcp CaLi2 undergoes a structural phase transition above 23 GPa to orthorhombic but does not dissociate into elemental Ca and Li. In the hcp phase a fit of the equation of state with the Murnaghan equation yields the bulk modulus Bo=15(2)GPa and dBo/dP=3.2(6) .

H2S adsorption and decomposition on the gradually reduced α-Fe2O3(001) surface: A DFT study

NASA Astrophysics Data System (ADS)

Lin, Changfeng; Qin, Wu; Dong, Changqing

2016-11-01

Reduction of iron based desulfurizer occurs during hot gas desulfurization process, which will affect the interaction between H2S and the desulfurizer surface. In this work, a detailed adsorption behavior and dissociation mechanism of H2S on the perfect and reduced α-Fe2O3(001) surfaces, as well as the correlation between the interaction characteristic and reduction degree of iron oxide, have been studied by using periodic density functional theory (DFT) calculations. Results demonstrate that H2S firstly chemisorbs on surface at relatively higher oxidation state (reduction degree χ < 33%), then dissociative adsorption occurs and becomes the main adsorption type after χ > 33%. Reduction of iron oxide benefits the H2S adsorption. Further, dissociation processes of H2S via molecular and dissociative adsorption were investigated. Results show that after reduction of Fe2O3 into the oxidation state around FeO and Fe, the reduced surface exhibits very strong catalytic capacity for H2S decomposition into S species. Meanwhile, the overall dissociation process on all surfaces is exothermic. These results provide a fundamental understanding of reduction effect of iron oxide on the interaction mechanism between H2S and desulfurizer surface, and indicate that rational control of reduction degree of desulfurizer is essential for optimizing the hot gas desulfurization process.

"I Feel Like I do Not Exist:" A Study of Dissociative Experiences Among War-Traumatized Refugee Youth.

PubMed

Gušić, Sabina; Malešević, Andrea; Cardeña, Etzel; Bengtsson, Hans; Søndergaard, Hans Peter

2017-11-20

War-traumatized refugee children and adolescents have been overlooked in research on trauma-related dissociation, and whatever research has been conducted has relied almost exclusively on questionnaires. The present study was an exploration of dissociative experiences in multitraumatized war-refugee youth. In this study, we used a mixed-method approach by grouping participants according to a Western-based dissociation measure (the Adolescent Dissociative Experiences Scale; Armstrong, Putnam, Carlson, Libero, & Smith, 1997), and conducting qualitative and quantitative analyses of their verbal descriptions of mental experiences related to dissociation in the aftermath of war and resettlement. The sample included 40 refugee youth, ages 13 to 21, 19 girls and 21 boys resettled in Sweden because of war and persecution. Severe trauma-related dissociation was a problem for a considerable subgroup of the sample. Some dissociative experiences were present in all the sample; others were restricted to the most dissociative group. The correlates of severe dissociation included high frequency and severity of emotional dysregulation and intensity, negative self- and body-perception, depressive mood, and experiences of detachment. Clinicians are urged to be aware of and assess trauma-related dissociation in war-refugee youth, and consider not only dissociative phenomena, but also other important processes such as emotional dysregulation. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Dissociative Identity Disorder

PubMed Central

2009-01-01

A brief description of the controversies surrounding the diagnosis of dissociative identity disorder is presented, followed by a discussion of the proposed similarities and differences between dissociative identity disorder and borderline personality disorder. The phenomenon of autohypnosis in the context of early childhood sexual trauma and disordered attachment is discussed, as is the meaning of alters or alternate personalities. The author describes recent neurosciences research that may relate the symptoms of dissociative identity disorder to demonstrable disordered attention and memory processes. A clinical description of a typical patient presentation is included, plus some recommendations for approaches to treatment. PMID:19724751

Direct measurement of exciton dissociation energy in polymers

NASA Astrophysics Data System (ADS)

Toušek, J.; Toušková, J.; Chomutová, R.; Paruzel, B.; Pfleger, J.

2017-01-01

Exciton dissociation energy was obtained based on the comparison of thickness of the space charge region estimated from the measurement of capacitance of prepared Schottky diode and from the measurement of photovoltage spectra. While the capacitance measurements provide information about the total width of the space charge region (SCR) the surface photovoltaic effect brings information only about the part of the SCR where electric field is sufficiently high to cause dissociation. For determination of the dissociation energy it is sufficient to find the electric potential in the SCR where the process starts.

Dissociative states in dreams and brain chaos: implications for creative awareness

PubMed Central

Bob, Petr; Louchakova, Olga

2015-01-01

This article reviews recent findings indicating some common brain processes during dissociative states and dreaming with the aim to outline a perspective that neural chaotic states during dreaming can be closely related to dissociative states that may manifest in dreams scenery. These data are in agreement with various clinical findings that dissociated states can be projected into the “dream scenery” in REM sleep periods and dreams may represent their specific interactions that may uncover unusual psychological potential of creativity in psychotherapy, art, and scientific discoveries. PMID:26441729

General features of the dissociative recombination of polyatomic molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pratt, S. T.; Jungen, Ch.; Schneider, I. F.

We discuss some aspects of a simple expression for the low-energy dissociative recombination cross section that applies when the recombination process is dominated by the indirect mechanism. In most previous applications, this expression has been applied to capture into vibrationally excited Rydberg states with the assumption that capture is always followed by prompt dissociation. Here we consider the dissociative recombination of larger polyatomic ions and electrons. More specifically, we consider capture into electronically core-excited Rydberg states, and begin to assess its potential importance for larger systems.

Dissociative recombination in aeronomy

NASA Technical Reports Server (NTRS)

Fox, J. L.

1989-01-01

The importance of dissociative recombination in planetary aeronomy is summarized, and two examples are discussed. The first is the role of dissociative recombination of N2(+) in the escape of nitrogen from Mars. A previous model is updated to reflect new experimental data on the electronic states of N produced in this process. Second, the intensity of the atomic oxygen green line on the nightside of Venus is modeled. Use is made of theoretical rate coefficients for production of O (1S) in dissociative recombination from different vibrational levels of O2(+).

General features of the dissociative recombination of polyatomic molecules

DOE PAGES

Pratt, S. T.; Jungen, Ch.; Schneider, I. F.; ...

2015-01-29

We discuss some aspects of a simple expression for the low-energy dissociative recombination cross section that applies when the recombination process is dominated by the indirect mechanism. In most previous applications, this expression has been applied to capture into vibrationally excited Rydberg states with the assumption that capture is always followed by prompt dissociation. Here we consider the dissociative recombination of larger polyatomic ions and electrons. More specifically, we consider capture into electronically core-excited Rydberg states, and begin to assess its potential importance for larger systems.

Single- and Dual-Process Models of Biased Contingency Detection.

PubMed

Vadillo, Miguel A; Blanco, Fernando; Yarritu, Ion; Matute, Helena

2016-01-01

Decades of research in causal and contingency learning show that people's estimations of the degree of contingency between two events are easily biased by the relative probabilities of those two events. If two events co-occur frequently, then people tend to overestimate the strength of the contingency between them. Traditionally, these biases have been explained in terms of relatively simple single-process models of learning and reasoning. However, more recently some authors have found that these biases do not appear in all dependent variables and have proposed dual-process models to explain these dissociations between variables. In the present paper we review the evidence for dissociations supporting dual-process models and we point out important shortcomings of this literature. Some dissociations seem to be difficult to replicate or poorly generalizable and others can be attributed to methodological artifacts. Overall, we conclude that support for dual-process models of biased contingency detection is scarce and inconclusive.

Method and apparatus for dissociating metals from metal compounds extracted into supercritical fluids

DOEpatents

Wai, Chien M.; Hunt, Fred H.; Smart, Neil G.; Lin, Yuehe

2000-01-01

A method for dissociating metal-ligand complexes in a supercritical fluid by treating the metal-ligand complex with heat and/or reducing or oxidizing agents is described. Once the metal-ligand complex is dissociated, the resulting metal and/or metal oxide form fine particles of substantially uniform size. In preferred embodiments, the solvent is supercritical carbon dioxide and the ligand is a .beta.-diketone such as hexafluoroacetylacetone or dibutyldiacetate. In other preferred embodiments, the metals in the metal-ligand complex are copper, silver, gold, tungsten, titanium, tantalum, tin, or mixtures thereof. In preferred embodiments, the reducing agent is hydrogen. The method provides an efficient process for dissociating metal-ligand complexes and produces easily-collected metal particles free from hydrocarbon solvent impurities. The ligand and the supercritical fluid can be regenerated to provide an economic, efficient process.

Chemistry at molecular junctions: Rotation and dissociation of O2 on the Ag(110) surface induced by a scanning tunneling microscope.

PubMed

Roy, Sharani; Mujica, Vladimiro; Ratner, Mark A

2013-08-21

The scanning tunneling microscope (STM) is a fascinating tool used to perform chemical processes at the single-molecule level, including bond formation, bond breaking, and even chemical reactions. Hahn and Ho [J. Chem. Phys. 123, 214702 (2005)] performed controlled rotations and dissociations of single O2 molecules chemisorbed on the Ag(110) surface at precise bias voltages using STM. These threshold voltages were dependent on the direction of the bias voltage and the initial orientation of the chemisorbed molecule. They also observed an interesting voltage-direction-dependent and orientation-dependent pathway selectivity suggestive of mode-selective chemistry at molecular junctions, such that in one case the molecule underwent direct dissociation, whereas in the other case it underwent rotation-mediated dissociation. We present a detailed, first-principles-based theoretical study to investigate the mechanism of the tunneling-induced O2 dynamics, including the origin of the observed threshold voltages, the pathway dependence, and the rate of O2 dissociation. Results show a direct correspondence between the observed threshold voltage for a process and the activation energy for that process. The pathway selectivity arises from a competition between the voltage-modified barrier heights for rotation and dissociation, and the coupling strength of the tunneling electrons to the rotational and vibrational modes of the adsorbed molecule. Finally, we explore the "dipole" and "resonance" mechanisms of inelastic electron tunneling to elucidate the energy transfer between the tunneling electrons and chemisorbed O2.

EEG source reconstruction evidence for the noun-verb neural dissociation along semantic dimensions.

PubMed

Zhao, Bin; Dang, Jianwu; Zhang, Gaoyan

2017-09-17

One of the long-standing issues in neurolinguistic research is about the neural basis of word representation, concerning whether grammatical classification or semantic difference causes the neural dissociation of brain activity patterns when processing different word categories, especially nouns and verbs. To disentangle this puzzle, four orthogonalized word categories in Chinese: unambiguous nouns (UN), unambiguous verbs (UV), ambiguous words with noun-biased semantics (AN), and ambiguous words with verb-biased semantics (AV) were adopted in an auditory task for recording electroencephalographic (EEG) signals from 128 electrodes on the scalps of twenty-two subjects. With the advanced current density reconstruction (CDR) algorithm and the constraint of standardized low-resolution electromagnetic tomography, the spatiotemporal brain dynamics of word processing were explored with the results that in multiple time periods including P1 (60-90ms), N1 (100-140ms), P200 (150-250ms) and N400 (350-450ms), noun-verb dissociation over the parietal-occipital and frontal-central cortices appeared not only between the UN-UV grammatical classes but also between the grammatically identical but semantically different AN-AV pairs. The apparent semantic dissociation within one grammatical class strongly suggests that the semantic difference rather than grammatical classification could be interpreted as the origin of the noun-verb neural dissociation. Our results also revealed that semantic dissociation occurs from an early stage and repeats in multiple phases, thus supporting a functionally hierarchical word processing mechanism. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Therapist concerns and process issues in grappling with functional autobiographical amnesia.

PubMed

Tripathi, Ravikesh; Bharath, Srikala; Desai, Geetha; Mehrotra, Seema

2013-07-01

Dissociative amnesia is relatively rare form of the dissociative disorder. This paper aims at describing the salient features of a case of functional autobiographical amnesia in a young adult and the approach adopted in the psychological management of this case. The case highlights concerns of the therapist at various stages of the therapy process.

A Symptom-Focused Hypnotic Approach to Accessing and Processing Previously Repressed/Dissociated Memories.

ERIC Educational Resources Information Center

Ratican, Kathleen L.

1996-01-01

The kinesthetic track back technique accesses the origins of current symptoms and may uncover previously repressed/dissociated material, if such material exists in the client's unconscious mind, is relevant to the symptoms, and is ready to be processed consciously. Case examples are given to illustrate proper use of this technique. (LSR)

Correlated ion and neutral time of flight technique combined with velocity map imaging: Quantitative measurements for dissociation processes in excited molecular nano-systems

NASA Astrophysics Data System (ADS)

Berthias, F.; Feketeová, L.; Della Negra, R.; Dupasquier, T.; Fillol, R.; Abdoul-Carime, H.; Farizon, B.; Farizon, M.; Märk, T. D.

2018-01-01

The combination of the Dispositif d'Irradiation d'Agrégats Moléculaire with the correlated ion and neutral time of flight-velocity map imaging technique provides a new way to explore processes occurring subsequent to the excitation of charged nano-systems. The present contribution describes in detail the methods developed for the quantitative measurement of branching ratios and cross sections for collision-induced dissociation processes of water cluster nano-systems. These methods are based on measurements of the detection efficiency of neutral fragments produced in these dissociation reactions. Moreover, measured detection efficiencies are used here to extract the number of neutral fragments produced for a given charged fragment.

Process dissociation between contextual retrieval and item recognition.

PubMed

Weis, Susanne; Specht, Karsten; Klaver, Peter; Tendolkar, Indira; Willmes, Klaus; Ruhlmann, Jürgen; Elger, Christian E; Fernández, Guillén

2004-12-22

We employed a source memory task in an event related fMRI study to dissociate MTL processes associated with either contextual retrieval or item recognition. To introduce context during study, stimuli (photographs of buildings and natural landscapes) were transformed into one of four single-color-scales: red, blue, yellow, or green. In the subsequent old/new recognition memory test, all stimuli were presented as gray scale photographs, and old-responses were followed by a four-alternative source judgment referring to the color in which the stimulus was presented during study. Our results suggest a clear-cut process dissociation within the human MTL. While an activity increase accompanies successful retrieval of contextual information, an activity decrease provides a familiarity signal that is sufficient for successful item recognition.

Programed dynamical ordering in self-organization processes of a nanocube: a molecular dynamics study.

PubMed

Harada, Ryuhei; Mashiko, Takako; Tachikawa, Masanori; Hiraoka, Shuichi; Shigeta, Yasuteru

2018-04-04

Self-organization processes of a gear-shaped amphiphile molecule (1) to form a hexameric structure (nanocube, 16) were inferred from sequential dissociation processes by using molecular dynamics (MD) simulations. Our MD study unveiled that programed dynamic ordering exists in the dissociation processes of 16. According to the dissociation processes, it is proposed that triple π-stacking among three 3-pyridyl groups and other weak molecular interactions such as CH-π and van der Waals interactions, some of which arise from the solvophobic effect, were sequentially formed in stable and transient oligomeric states in the self-organization processes, i.e.12, 13, 14, and 15. By subsequent analyses on structural stabilities, it was found that 13 and 14 are stable intermediate oligomers, whereas 12 and 15 are transient ones. Thus, the formation of 13 from three monomers and of 16 from 14 and two monomers via corresponding transients is time consuming in the self-assembly process.

The influence of porosity and structural parameters on different kinds of gas hydrate dissociation

PubMed Central

Misyura, S. Y.

2016-01-01

Methane hydrate dissociation at negative temperatures was studied experimentally for different artificial and natural samples, differing by macro- and micro-structural parameters. Four characteristic dissociation types are discussed in the paper. The internal kinetics of artificial granule gas hydrates and clathrate hydrates in coal is dependent on the porosity, defectiveness and gas filtration rate. The density of pores distribution in the crust of formed ice decreases by the several orders of magnitude and this change significantly the rate of decay. Existing models for describing dissociation at negative temperatures do not take into account the structural parameters of samples. The dissociation is regulated by internal physical processes that must be considered in the simulation. Non-isothermal dissociation with constant external heat flux was simulated numerically. The dissociation is simulated with consideration of heat and mass transfer, kinetics of phase transformation and gas filtering through a porous medium of granules for the negative temperatures. It is shown that the gas hydrate dissociation in the presence of mainly microporous structures is fundamentally different from the disintegration of gas hydrates containing meso and macropores. PMID:27445113

Is there a complex relation between social anxiety disorder, childhood traumatic experiences and dissociation?

PubMed

Belli, Hasan; Akbudak, Mahir; Ural, Cenk; Solmaz, Mustafa; Dogan, Zuhal; Konkan, Ramazan

2017-01-01

A possible relationship has been suggested between social anxiety and dissociation. Traumatic experiences, especially childhood abuse, play an important role in the aetiology of dissociation. This study assesses childhood trauma history, dissociative symptoms, and dissociative disorder comorbidity in patients with social anxiety disorder (SAD). The 94 psychotropic drug-naive patients participating in the study had to meet DSM-IV criteria for SAD. Participants were assessed using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D), the Dissociation Questionnaire (DIS-Q), the Liebowitz Social Anxiety Scale (LSAS), and the Childhood Trauma Questionnaire (CTQ). Patients were divided into two groups using the DIS-Q, and the two groups were compared. The evaluation found evidence of at least one dissociative disorder in 31.91% of participating patients. The most prevalent disorders were dissociative disorder not otherwise specified (DDNOS), dissociative amnesia, and depersonalization disorders. Average scores on LSAS and fear and avoidance sub-scale averages were significantly higher among the high DIS-Q group (p < .05). In a logistic regression taking average LSAS scores as the dependent variable, the five independent variables DIS-Q, CTQ-53 total score, emotional abuse, sexual abuse, and emotional neglect were associated with average LSAS scores among patients with SAD (p < .05). It is concluded that, on detecting SAD symptoms during hospitalization, the clinician should not neglect underlying dissociative processes and traumatic experiences among these patients.

Phase behaviour of methane clathrate under conditions relevant to Titan's interior

NASA Astrophysics Data System (ADS)

Sclater, G.; Wood, I. G.; Tucker, M. G.; Crawford, I. A.; Fortes, A. D.

2013-09-01

Microporous gas hydrates - known as clathrates - are common on the Earth and are also thought to be abundant in the outer Solar System [1]. The conditions for the existence of clathrates prevail throughout the Solar System and they are considered to be abundant from the Martian permafrost to the surfaces and interiors of many icy satellites [7]. These materials have been extensively studied in the range 0 - 5 GPa at ambient temperatures [2-5]; however, their behaviour in the range close to the dissociation (or melting) point is not well known at all, with some suggesting the occurrence of a facecentred cubic (sII) phase, and others that the clathrate becomes unstable with respect to mixtures of solid methane and ice. The high-pressure behaviour underpins planetary modelling; for example, the behaviour of methane hydrate in the ranges 0-6 GPa and 100-400 K is crucial to accurate modelling of Saturn's largest moon, Titan where clathrates are hypothesised to be the source of CH4 in Titan's atmosphere [6]. In order to address these problems we are carrying out a program of investigation using neutron diffraction to investigate the phase behaviour of methane clathrate close to its dissociation temperature in the 0.6-2.5 GPa region. Our goals were to obtain data to provide the first in-situ diffraction-based evidence for the phase behaviour of methane clathrate near to its high-pressure dissociation temperature (along with a control measurement at room temperature for comparison with other workers), to obtain P-V curves along two isotherms for each of the phases observed, and to complete structure refinements of all three clathrate polymorphs, thereby allowing us to carry out a full audit of the methane concentration in each phase as a function of pressure (including cage occupancies). Thus far we have successfully completed our RT measurements and will make the higher temperature observations in July 2013; we anticipate being able to report our findings from this second experimental run at the EPSC.

Weak "A" blood subgroup discrimination by a rheo-optical method: a new application of laser backscattering

NASA Astrophysics Data System (ADS)

Rasia, Rodolfo J.; Rasia-Valverde, Juana R.; Stoltz, Jean F.

1996-01-01

Laser backscattering is an excellent tool to investigate size and concentration of suspended particles. It was successfully applied to the analysis of erythrocyte aggregation. A method is proposed that applies laser backscattering to the evaluation of the strength of the immunologic erythrocyte agglutination by approaching the energy required for the mechanical dissociation of agglutinates. Mills and Snabre have proposed a theory of laser backscattering for erythrocyte aggregation analysis. It is applied here to analyze the dissociation process of erythrocyte agglutinates performed by imposing a constant shear rate to the agglutinate suspension in a couette viscometer until a dispersion of isolated red cells is attained. Experimental verifications of the method were performed on the erythrocytes of the ABO group reacting against an anti-A test serum in twofold series dilutions. Spent energy is approached by a numerical process carried out on the backscattered intensity data registered during mechanical dissociation. Velocities of agglutination and dissociation lead to the calculation of dissociation parameters These values are used to evaluate the strength of the immunological reaction and to discriminate weak subgroups of ABO system.

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

NASA Astrophysics Data System (ADS)

Wlazło, M.; Majewski, J. A.

2018-03-01

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

Dissociation and Internal Excitation of Molecular Nitrogen Due to N + N2 Collisions Using Direct Molecular Simulation

NASA Technical Reports Server (NTRS)

Grover, Maninder S.; Schwartzentruber, Thomas E.; Jaffe, Richard L.

2017-01-01

In this work we present a molecular level study of N2+N collisions, focusing on excitation of internal energy modes and non-equilibrium dissociation. The computation technique used here is the direct molecular simulation (DMS) method and the molecular interactions have been modeled using an ab-initio potential energy surface (PES) developed at NASA's Ames Research Center. We carried out vibrational excitation calculations between 5000K and 30000K and found that the characteristic vibrational excitation time for the N + N2 process was an order of magnitude lower than that predicted by the Millikan and White correlation. It is observed that during vibrational excitation the high energy tail of the vibrational energy distribution gets over populated first and the lower energy levels get populated as the system evolves. It is found that the non-equilibrium dissociation rate coefficients for the N + N2 process are larger than those for the N2 + N2 process. This is attributed to the non-equilibrium vibrational energy distributions for the N + N2 process being less depleted than that for the N2 +N2 process. For an isothermal simulation we find that the probability of dissociation goes as 1/T(sub tr) for molecules with internal energy (epsilon(sub int)) less than approximately 9.9eV, while for molecules with epsilon (sub int) greater than 9.9eV the dissociation probability was weakly dependent on translational temperature of the system. We compared non-equilibrium dissociation rate coefficients and characteristic vibrational excitation times obtained by using the ab-initio PES developed at NASA's Ames Research Center to those obtained by using an ab-initio PES developed at the University of Minnesota. Good agreement was found between the macroscopic properties and molecular level description of the system obtained by using the two PESs.

Dissociative symptoms are associated with reduced neuropsychological performance in patients with recurrent depression and a history of trauma exposure

PubMed Central

Frewen, Paul A.; Oremus, Carolina; Lanius, Ruth A.; McKinnon, Margaret C.

2016-01-01

Background Although preliminary work suggests that dissociative symptoms may impact neuropsychological performance in trauma-exposed populations, the relation between dissociation and cognitive performance has not been explored in patients with depression. Objective The present study examined dissociative symptoms in relation to neuropsychological performance in participants with a primary diagnosis of recurrent major depressive disorder (MDD) and a history of trauma exposure. Method Twenty-three participants with MDD and 20 healthy controls who did not differ in age, sex, education, or IQ were assessed. In addition to a standardized neuropsychological battery assessing frontotemporally mediated cognitive processes, participants completed clinical measures assessing dissociative symptoms, illness severity, and past history of trauma exposure. Results Among participants with MDD, greater severity of derealization was associated with reduced performance on measures of delayed visuospatial recall and recognition on a task of verbal memory recognition. In addition, more severe depersonalization was associated with slower processing speed and a response style lending itself toward better performance in a less active environment. Conclusions These findings point toward dissociative symptoms as a transdiagnostic factor associated with neuropsychological dysfunction in patients with depression and a history of trauma. Limitations and recommendations for future research are discussed. PMID:26927902

Identifying dissociative identity disorder: a self-report and projective study.

PubMed

Scroppo, J C; Drob, S L; Weinberger, J L; Eagle, P

1998-05-01

This study compared 21 female adult psychiatric patients diagnosed with dissociative identity disorder (DID) with 21 female adult nondissociative psychiatric patients to determine whether DID patients exhibit a distinguishing set of clinical features, and perceptual, attentional, and cognitive processes. Participants were assessed with the Dissociative Disorders Interview Schedule to assess diagnostic status. Group scores on the Dissociative Experiences Scale, Tellegen Absorption Scale, Childhood Trauma Questionnaire, Brief Symptom Inventory, and the Rorschach test were compared. DID participants reported earlier and more severe childhood trauma, more dissociative symptoms, and a greater propensity for altered states of consciousness. The DID participants also exhibited increased projective and imaginative activity, a diminished ability to integrate mental contents, a complex and driven cognitive style, and a highly unconventional view of reality.

Dissociative identity disorder: a controversial diagnosis.

PubMed

Gillig, Paulette Marie

2009-03-01

A brief description of the controversies surrounding the diagnosis of dissociative identity disorder is presented, followed by a discussion of the proposed similarities and differences between dissociative identity disorder and borderline personality disorder. The phenomenon of autohypnosis in the context of early childhood sexual trauma and disordered attachment is discussed, as is the meaning of alters or alternate personalities. The author describes recent neurosciences research that may relate the symptoms of dissociative identity disorder to demonstrable disordered attention and memory processes. A clinical description of a typical patient presentation is included, plus some recommendations for approaches to treatment.

Dissociative Ionization of Pyridine by Electron Impact

NASA Technical Reports Server (NTRS)

Dateo, Christopher; Huo, Winifred; Kwak, Dochan (Technical Monitor)

2002-01-01

In order to understand the damage of biomolecules by electrons, a process important in radiation damage, we undertake a study of the dissociative ionization (DI) of pyridine (C5H5N) from the low-lying ionization channels. The methodology used is the same as in the benzene study. While no experimental DI data are available, we compare the dissociation products from our calculations with the dissociative photoionization measurements of Tixier et al. using dipole (e, e(+) ion) coincidence spectroscopy. Comparisons with the DI of benzene is also made so as to understand the difference in DI between a heterocyclic and an aromatic molecule.

An integrated experimental and theoretical reaction path search: analyses of the multistage reaction of an ionized diethylether dimer involving isomerization, proton transfer, and dissociation.

PubMed

Matsuda, Yoshiyuki; Xie, Min; Fujii, Asuka

2018-05-30

An ionization-induced multistage reaction of an ionized diethylether (DEE) dimer involving isomerization, proton transfer, and dissociation is investigated by combining infrared (IR) spectroscopy, tandem mass spectrometry, and a theoretical reaction path search. The vertically-ionized DEE dimer isomerizes to a hydrogen-bonded cluster of protonated DEE and the [DEE-H] radical through barrierless intermolecular proton transfer from the CH bond of the ionized moiety. This isomerization process is confirmed by IR spectroscopy and the theoretical reaction path search. The multiple dissociation pathways following the isomerization are analyzed by tandem mass spectrometry. The isomerized cluster dissociates stepwise into a [protonated DEE-acetaldehyde (AA)] cluster, protonated DEE, and protonated AA. The structure of the fragment ion is also analyzed by IR spectroscopy. The reaction map of the multistage processes is revealed through a harmony of these experimental and theoretical methods.

Revealing the Self-Degradation Mechanisms in Methylammonium Lead Iodide Perovskites in Dark and Vacuum.

PubMed

Gunasekaran, Rajendra Kumar; Chinnadurai, Deviprasath; Selvaraj, Aravindha Raja; Rajendiran, Rajmohan; Senthil, Karuppanan; Prabakar, Kandasamy

2018-06-19

Organic-inorganic lead halide perovskite phases segregate (and their structures degrade) under illumination, exhibiting a poor stability with hysteresis and producing halide accumulation at the surface.In this work, we observed structural and interfacial dissociation in methylammonium lead iodide (CH 3 NH 3 PbI 3 ) perovskites even under dark and vacuum conditions. Here, we investigate the origin and consequences of self-degradation in CH 3 NH 3 PbI 3 perovskites stored in the dark under vacuum. Diffraction and photoelectron spectroscopic studies reveal the structural dissociation of perovskites into PbI 2 , which further dissociates into metallic lead (Pb 0 ) and I 2 - ions, collectively degrading the perovskite stability. Using TOF-SIMS analysis, AuI 2 - formation was directly observed, and it was found that an interplay between CH 3 NH 3 + , I 3 - , and mobile I - ions continuously regenerates more I 2 - ions, which diffuse to the surface even in the absence of light. Besides, halide diffusion causes a concentration gradient between Pb 0 and I 2 - and creates other ionic traps (PbI 2 - , PbI - ) that segregate as clusters at the perovskite/gold interface. A shift of the onset of the absorption band edge towards shorter wavelengths was also observed by absorption spectroscopy, indicating the formation of defect species upon aging in the dark under vacuum. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cognitive abuse within the incestuous family as a factor in the development of dissociative identity disorder.

PubMed

Reed-Gavish, Maya

2013-01-01

The polarized nature of the ongoing controversies surrounding the genesis and validity of dissociative identity disorder pit advocates who see and work with dissociative identity disorder sufferers against skeptics who claim it to be an artificial iatrogenically produced phenomenon. This paper suggests that such a dichotomy is unwarranted and that, in fact, both sides of the argument have merit. A short description of the controversy that rages among professionals is followed by a personal-experiential review of the development of dissociative identities in the author. Using sociocognitive conceptualizations and describing the iatrogenic intrafamilial processes that led to the "choice" of dissociation as a strategy for coping with a traumatic reality, this paper shows how both sides of the conflict complement each other and suggests a new way of understanding the developmental pathway of dissociative identity disorder.

Unresolved mourning, supernatural beliefs and dissociation: a mediation analysis.

PubMed

Thomson, Paula; Jaque, S Victoria

2014-01-01

Unresolved mourning is marked by disorganized behavior and states of mind. In this study, we speculated that pathological dissociation would mediate the effects of unresolved mourning on supernatural beliefs. This hypothesis was determined based on findings that indicate an association between higher levels of dissociation, stronger beliefs in the supernatural and unresolved mourning. We examined two groups of participants, one classified as non-unresolved (non-U) (n = 56) and the other as unresolved (n = 26) (U) with respect to past loss/trauma as measured by the Adult Attachment Interview (AAI). Two self-report instruments were administered to measure supernatural beliefs and dissociation. As hypothesized, the multivariate analysis of variance indicated mean differences between the two groups. The unresolved group had greater belief in the supernatural and more pathological dissociative processes. The mediation analysis demonstrated that pathological dissociation fully mediated the effects of unresolved mourning on supernatural beliefs.

Dissociation between melodic and rhythmic processing during piano performance from musical scores.

PubMed

Bengtsson, Sara L; Ullén, Fredrik

2006-03-01

When performing or perceiving music, we experience the melodic (spatial) and rhythmic aspects as a unified whole. Moreover, the motor program theory stipulates that the relative timing and the serial order of the movement are invariant features of a motor program. Still, clinical and psychophysical observations suggest independent processing of these two aspects, in both production and perception. Here, we used functional magnetic resonance imaging to dissociate between brain areas processing the melodic and the rhythmic aspects during piano playing from musical scores. This behavior requires that the pianist decodes two types of information from the score in order to produce the desired piece of music. The spatial location of a note head determines which piano key to strike, and the various features of the note, such as the stem and flags determine the timing of each key stroke. We found that the medial occipital lobe, the superior temporal lobe, the rostral cingulate cortex, the putamen and the cerebellum process the melodic information, whereas the lateral occipital and the inferior temporal cortex, the left supramarginal gyrus, the left inferior and ventral frontal gyri, the caudate nucleus, and the cerebellum process the rhythmic information. Thus, we suggest a dissociate involvement of the dorsal visual stream in the spatial pitch processing and the ventral visual stream in temporal movement preparation. We propose that this dissociate organization may be important for fast learning and flexibility in motor control.

Equations for calculating the properties of dissociated steam

NASA Astrophysics Data System (ADS)

Aminov, R. Z.; Gudym, A. A.

2017-08-01

The equations of state for dissociated steam have been developed in the temperature and pressure ranges of 1250-2300 K and 0.01-10.00 MPa for calculating thermodynamic processes in thermal power units operating on high-temperature steam. These equations are based on the property tables for dissociated steam derived at a reference temperature of 0 K. It is assumed that the initial substance is steam, the dissociation of which—in accordance with the most likely chemical reactions—results in formation of molecules of hydrogen, oxygen, steam, hydroxyl, and atoms of oxygen and hydrogen. Differential thermodynamic correlations, considering a change in the chemical potential and the composition of the mixture, during the steam dissociation are used. A reference temperature of 0.01°C used in the calculation of parameters of nondissociated steam has been adopted to predict processes in thermal power units without matching the reference temperatures and to account for transformation of dissociated steam into its usual form for which there is the international system of equations with the water triple point of 0.01°C taken as the reference. In the investigated region, the deviation of dissociated steam properties from those of nondissociated steam, which increases with decreasing the pressure or increasing the temperature, was determined. For a pressure of 0.02 MPa and a temperature of 2200 K, these deviations are 512 kJ/kg for the enthalpy, 0.2574 kJ/(kg K) for the entropy, and 3.431 kJ/(kg K) for the heat capacity at constant pressure. The maximum deviation of the dissociated steam properties calculated by the developed equations from the handbook values that these equations are based on does not exceed 0.03-0.05%.

Superior colliculus resting state networks in post-traumatic stress disorder and its dissociative subtype.

PubMed

Olivé, Isadora; Densmore, Maria; Harricharan, Sherain; Théberge, Jean; McKinnon, Margaret C; Lanius, Ruth

2018-01-01

The innate alarm system (IAS) models the neurocircuitry involved in threat processing in posttraumatic stress disorder (PTSD). Here, we investigate a primary subcortical structure of the IAS model, the superior colliculus (SC), where the SC is thought to contribute to the mechanisms underlying threat-detection in PTSD. Critically, the functional connectivity between the SC and other nodes of the IAS remains unexplored. We conducted a resting-state fMRI study to investigate the functional architecture of the IAS, focusing on connectivity of the SC in PTSD (n = 67), its dissociative subtype (n = 41), and healthy controls (n = 50) using region-of-interest seed-based analysis. We observed group-specific resting state functional connectivity between the SC for both PTSD and its dissociative subtype, indicative of dedicated IAS collicular pathways in each group of patients. When comparing PTSD to its dissociative subtype, we observed increased resting state functional connectivity between the left SC and the right dorsolateral prefrontal cortex (DLPFC) in PTSD. The DLPFC is involved in modulation of emotional processes associated with active defensive responses characterising PTSD. Moreover, when comparing PTSD to its dissociative subtype, increased resting state functional connectivity was observed between the right SC and the right temporoparietal junction in the dissociative subtype. The temporoparietal junction is involved in depersonalization responses associated with passive defensive responses typical of the dissociative subtype. Our findings suggest that unique resting state functional connectivity of the SC parallels the unique symptom profile and defensive responses observed in PTSD and its dissociative subtype. Hum Brain Mapp 39:563-574, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Initial mechanisms for the dissociation of carbon from electronically-excited nitrotoluene molecules

NASA Astrophysics Data System (ADS)

Yuan, Bing; Eilers, Hergen

2017-12-01

We calculated the photoinduced decomposition of various nitrotoluene molecules, resulting in the formation of atomic carbon, at the B3LYP/6-311++G(d,p) level of theory using Gaussian 09. In addition, we used TD-DFT (B3LYP/6-311++G(d,p)) to calculate the excitation energies. The results confirm our previously reported experimental results. Specifically, we show that the absorption of 226 nm (5.49 eV) light can lead to the decomposition of nitrotoluene molecules and the formation of atomic carbon. One 226 nm photon is sufficient for the dissociation of carbon from 2-NT and 4-NT molecules. During the dissociation process, the CH3 group provides the dissociated carbon atom and the NO2 group accepts the H atoms from either the CH3 group or the benzene ring before carbon exits the molecular system. For the second and third carbon dissociation of 2-NT, the energy barriers are 6.70 eV and 7.43 eV, respectively, and two 226 nm photons would need to be absorbed by the molecule. If extra NO is present during the first carbon dissociation of 2-NT, it gets involved in the last two decomposition steps and forms a C=NH-N=O structure which stabilizes the decomposition products and lowers the energy barrier from 5.22 eV to 4.70 eV. However, for the second and third carbon dissociation of 2-NT, the NO molecules have no apparent effect. For nitrotoluene molecules with two or three NO2 groups (i.e., 2,4-DNT, 2,6-DNT, 3,4-DNT, and 2,4,6-TNT), the first carbon dissociation energies are between 5.26 eV and 5.57 eV. The carbon dissociation pathways for these molecules are similar to those of 2-NT. In 2,4-DNT, the lowest energy barriers for the second and third carbon dissociation are 6.54 eV and 6.60 eV, respectively, which are about 1 eV higher than the energy barrier for the first carbon dissociation. In case of 2,4-DNT/NO and 2,4,6-TNT/NO, NO acts as a catalyst in the first carbon dissociation processes and forms a C=NH-N=O structure which lowers the energy barriers by 0.48 eV and 0.89 eV, respectively.

Cross sections for the dissociative attachment of electrons to NO

NASA Technical Reports Server (NTRS)

Krishnakumar, E.; Srivastava, S. K.

1988-01-01

Cross sections for the production of O(-) by electron attachment to NO are reported. It is found that the maximum value of the cross section is about 52 percent higher than the measurement of Rapp and Briglia (1965). Cross sections for the process of polar dissociation, e + NO yields N(+) + O(_), have also been measured, and the threshold energy for this process has been obtained.

Structural brain aberrations associated with the dissociative subtype of post-traumatic stress disorder.

PubMed

Daniels, J K; Frewen, P; Theberge, J; Lanius, R A

2016-03-01

One factor potentially contributing to the heterogeneity of previous results on structural grey matter alterations in adult participants suffering from post-traumatic stress disorder (PTSD) is the varying levels of dissociative symptomatology. The aim of this study was therefore to test whether the recently defined dissociative subtype of PTSD characterized by symptoms of depersonalization and derealization is characterized by specific differences in volumetric brain morphology. Whole-brain MRI data were acquired for 59 patients with PTSD. Voxel-based morphometry was carried out to test for group differences between patients classified as belonging (n = 15) vs. not belonging (n = 44) to the dissociative subtype of PTSD. The correlation between dissociation (depersonalization/derealization) severity and grey matter volume was computed. Patients with PTSD classified as belonging to the dissociative subtype exhibited greater grey matter volume in the right precentral and fusiform gyri as well as less volume in the right inferior temporal gyrus. Greater dissociation severity was associated with greater volume in the right middle frontal gyrus. The results of this first whole-brain investigation of specific grey matter volume in dissociative subtype PTSD indentified structural aberrations in regions subserving the processing and regulation of emotional arousal. These might constitute characteristic biomarkers for the dissociative subtype PTSD. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Line Profile of H Lyman (alpha) from Dissociative Excitation of H2 with Application to Jupiter

NASA Technical Reports Server (NTRS)

Ajello, Joseph M.; Kasnik, Isik; Ahmed, Syed M.; Clarke, John T.

1995-01-01

Observations of the H Lyman(alpha) (Ly-alpha) emission from Jupiter have shown pronounced emissions, exceeding solar fluorescence, in the polar aurora and equatorial "bulge" regions. The H Ly-alpha line profiles from these regions are broader than expected, indicating high-energy processes producing fast atoms as determined from the observed Doppler broadening. Toward understanding that process a high-resolution ultraviolet (UV) spectrometer was employed for the first measurement of the H Ly-alpha emission Doppler profile from dissociative excitation of H2 by electron impact. Analysis of the deconvolved line profile reveals the existence of a narrow central peak of 40 +/- 4 mA full width at half maximum and a broad pedestal base about 240 mA wide. Two distinct dissociation mechanisms account for this Doppler structure. Slow H(2p) atoms characterized by a distribution function with peak energy near 80 meV produce the peak profile, which is nearly independent of the electron impact energy. Slow H(2p) atoms arise from direct dissociation and predissociation of singly excited states which have a dissociation limit of 14.68 eV. The wings of H Ly-alpha arise from dissociative excitation of a series of doubly excited states which cross the Franck-Condon region between 23 and 40 eV. The profile of the wings is dependent on the electron impact energy, and the distribution function of fast H(2p) atoms is therefore dependent on the electron impact energy. The fast atom kinetic energy distribution at 100 eV electron impact energy spans the energy range from 1 to 10 eV with a peak near 4 eV. For impact energies above 23 eV the fast atoms contribute to a slightly asymmetric structure of the line profile. The absolute cross sections of the H Ly-alpha line peak and wings were measured over the range from 0 to 200 eV. Analytic model coefficients are given for the measured cross sections which can be applied to planetary atmosphere auroral and dayglow calculations. The dissociative excitation process, while one contributing process, appears insufficient by itself to explain the line broadening observed at Jupiter.

Errors and conflict at the task level and the response level.

PubMed

Desmet, Charlotte; Fias, Wim; Hartstra, Egbert; Brass, Marcel

2011-01-26

In the last decade, research on error and conflict processing has become one of the most influential research areas in the domain of cognitive control. There is now converging evidence that a specific part of the posterior frontomedian cortex (pFMC), the rostral cingulate zone (RCZ), is crucially involved in the processing of errors and conflict. However, error-related research has focused primarily on a specific error type, namely, response errors. The aim of the present study was to investigate whether errors on the task level rely on the same neural and functional mechanisms. Here we report a dissociation of both error types in the pFMC: whereas response errors activate the RCZ, task errors activate the dorsal frontomedian cortex. Although this last region shows an overlap in activation for task and response errors on the group level, a closer inspection of the single-subject data is more in accordance with a functional anatomical dissociation. When investigating brain areas related to conflict on the task and response levels, a clear dissociation was perceived between areas associated with response conflict and with task conflict. Overall, our data support a dissociation between response and task levels of processing in the pFMC. In addition, we provide additional evidence for a dissociation between conflict and errors both at the response level and at the task level.

Visuomotor 'immunity' to perceptual illusion: a mismatch of attentional demands cannot explain the perception-action dissociation.

PubMed

Dewar, Michaela T; Carey, David P

2006-01-01

Recent findings of visuomotor immunity to perceptual illusions have been attributed to a perception-action division of labour within two anatomically segregated streams in the visual cortex. However, critics argue that such experimental findings are not valid and have suggested that the perception-action dissociations can be explained away by differential attentional/processing demands, rather than a functional dissociation in the neurologically intact brain: perceptual tasks require processing of the entire illusion display while visuomotor tasks only require processing the target that is acted upon. The present study examined whether grasping of the Müller-Lyer display would remain immune to the illusion when the task required the direction of attention or a related resource towards both Müller-Lyer shafts. Twelve participants were required to match and grasp two Müller-Lyer shafts bimanually (i.e. one with each hand). It was found that bimanual grasping was not significantly affected by the illusion, while there was a highly significant illusion effect on perceptual estimation by matching. Furthermore, it was established that this dissociation did not result from a differing baseline rate of change in manual estimation and grasping aperture to a change in physical object size. These findings provide further support for the postulated perception-action dissociation and fail to uphold the idea that grasping 'immunity' to the Müller-Lyer illusions merely represents an experimental artefact.

Measuring automatic retrieval: a comparison of implicit memory, process dissociation, and speeded response procedures.

PubMed

Horton, Keith D; Wilson, Daryl E; Vonk, Jennifer; Kirby, Sarah L; Nielsen, Tina

2005-07-01

Using the stem completion task, we compared estimates of automatic retrieval from an implicit memory task, the process dissociation procedure, and the speeded response procedure. Two standard manipulations were employed. In Experiment 1, a depth of processing effect was found on automatic retrieval using the speeded response procedure although this effect was substantially reduced in Experiment 2 when lexical processing was required of all words. In Experiment 3, the speeded response procedure showed an advantage of full versus divided attention at study on automatic retrieval. An implicit condition showed parallel effects in each study, suggesting that implicit stem completion may normally provide a good estimate of automatic retrieval. Also, we replicated earlier findings from the process dissociation procedure, but estimates of automatic retrieval from this procedure were consistently lower than those from the speeded response procedure, except when conscious retrieval was relatively low. We discuss several factors that may contribute to the conflicting outcomes, including the evidence for theoretical assumptions and criterial task differences between implicit and explicit tests.

Single- and Dual-Process Models of Biased Contingency Detection

PubMed Central

2016-01-01

Abstract. Decades of research in causal and contingency learning show that people’s estimations of the degree of contingency between two events are easily biased by the relative probabilities of those two events. If two events co-occur frequently, then people tend to overestimate the strength of the contingency between them. Traditionally, these biases have been explained in terms of relatively simple single-process models of learning and reasoning. However, more recently some authors have found that these biases do not appear in all dependent variables and have proposed dual-process models to explain these dissociations between variables. In the present paper we review the evidence for dissociations supporting dual-process models and we point out important shortcomings of this literature. Some dissociations seem to be difficult to replicate or poorly generalizable and others can be attributed to methodological artifacts. Overall, we conclude that support for dual-process models of biased contingency detection is scarce and inconclusive. PMID:27025532

Relative impact of H 2 O and O 2 in the oxidation of UO 2 powders from 50 to 300 °C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong

Here, we studied the reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO 2) powder at elevated temperature by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). We observed and quatified oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Relative impact of H2O and O2 in the oxidation of UO2 powders from 50 to 300 °C

NASA Astrophysics Data System (ADS)

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong; Roberts, Sarah K.; Nelson, Art J.

2017-12-01

The reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO2) powder at elevated temperature was studied by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). Oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice was observed and quantified. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Relative impact of H 2 O and O 2 in the oxidation of UO 2 powders from 50 to 300 °C

DOE PAGES

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong; ...

2017-10-04

Here, we studied the reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO 2) powder at elevated temperature by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). We observed and quatified oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Hemispheric association and dissociation of voice and speech information processing in stroke.

PubMed

Jones, Anna B; Farrall, Andrew J; Belin, Pascal; Pernet, Cyril R

2015-10-01

As we listen to someone speaking, we extract both linguistic and non-linguistic information. Knowing how these two sets of information are processed in the brain is fundamental for the general understanding of social communication, speech recognition and therapy of language impairments. We investigated the pattern of performances in phoneme versus gender categorization in left and right hemisphere stroke patients, and found an anatomo-functional dissociation in the right frontal cortex, establishing a new syndrome in voice discrimination abilities. In addition, phoneme and gender performances were most often associated than dissociated in the left hemisphere patients, suggesting a common neural underpinnings. Copyright © 2015 Elsevier Ltd. All rights reserved.

Products of Dissociative Recombination in the Ionosphere

NASA Technical Reports Server (NTRS)

Cosby, Philip

1996-01-01

SRI International undertook a novel experimental measurement of the product states formed by dissociative ro-combination (DR) of C2(+), NO(+), and N2(+) as a function of both electron energy and reactant ion vibrational level. For these measurements we used a recently developed experimental technique for measuring dissociation product distributions that allows both the branching ratios to be accurately determined and the electronic and ro-vibrational state composition of the reactant ions to be specified. DR is the dominant electron loss mechanism in all regions of the ionosphere. In this process, electron attachment to the molecular ion produces an unstable neutral molecule that rapidly dissociates.

Dissociated neural basis of two behavioral hallmarks of holistic face processing: The whole-part effect and composite-face effect.

PubMed

Li, Jin; Huang, Lijie; Song, Yiying; Liu, Jia

2017-07-28

It has been long proposed that our extraordinary face recognition ability stems from holistic face processing. Two widely-used behavioral hallmarks of holistic face processing are the whole-part effect (WPE) and composite-face effect (CFE). However, it remains unknown whether these two effects reflect similar or different aspects of holistic face processing. Here we investigated this question by examining whether the WPE and CFE involved shared or distinct neural substrates in a large sample of participants (N=200). We found that the WPE and CFE showed hemispheric dissociation in the fusiform face area (FFA), that is, the WPE was correlated with face selectivity in the left FFA, while the CFE was correlated with face selectivity in the right FFA. Further, the correlation between the WPE and face selectivity was largely driven by the FFA response to faces, whereas the association between the CFE and face selectivity resulted from suppressed response to objects in the right FFA. Finally, we also observed dissociated correlation patterns of the WPE and CFE in other face-selective regions and across the whole brain. These results suggest that the WPE and CFE may reflect different aspects of holistic face processing, which shed new light on the behavioral dissociations of these two effects demonstrated in literature. Copyright © 2017 Elsevier Ltd. All rights reserved.

Direct graphene growth on MgO: origin of the band gap.

PubMed

Gaddam, Sneha; Bjelkevig, Cameron; Ge, Siping; Fukutani, Keisuke; Dowben, Peter A; Kelber, Jeffry A

2011-02-23

A 2.5 monolayer (ML) thick graphene film grown by chemical vapor deposition of thermally dissociated C(2)H(4) on MgO(111), displays a significant band gap. The apparent six-fold low energy electron diffraction (LEED) pattern actually consists of two three-fold patterns with different 'A' and 'B' site diffraction intensities. Similar effects are observed for the LEED patterns of a 1 ML carbon film derived from annealing adventitious carbon on MgO(111), and for a 1.5 ML thick graphene film grown by sputter deposition on the 1 ML film. The LEED data indicate different electron densities at the A and B sites of the graphene lattice, suggesting that the observed band gap results from lifting the graphene HOMO/LUMO degeneracy at the Dirac point. The data also indicate that disparities in A site/B site LEED intensities decrease with increasing carbon overlayer thickness, suggesting that the graphene band gap size decreases with increasing number of graphene layers on MgO(111). © 2011 IOP Publishing Ltd

Filming nuclear dynamics of iodine using x-ray diffraction at the LCLS

NASA Astrophysics Data System (ADS)

Ware, Matthew; Natan, Adi; Glownia, James; Cryan, James; Bucksbaum, Phil

2017-04-01

We will provide an overview of our analysis of the nuclear dynamics of iodine. At the LCLS, we pumped a gas cell of iodine with a weak 520nm, 50 fs pulse, and the nuclear dynamics are then probed with 9 keV, 40 fs x-rays with variable time delay. This allows us to simultaneously image nuclear wavepackets on the dissociating A state, on the bound B state, and even Raman wavepackets in the ground electronic state. We will explain at length how we isolate each of these signals using a Legendre decomposition of our x-ray data and the selection rules for each of the transitions. Likewise, we will discuss how we convert the x-ray diffraction patterns into real-space movies of the nuclear dynamics. Research supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Atomic, Molecular, and Optical Science Program. Use of LCLS supported under DOE Contract No. DE-AC02-76F00515.

Search for dilute excited states in 16O

NASA Astrophysics Data System (ADS)

Ogloblin, A. A.; Danilov, A. N.; Demyanova, A. S.; Goncharov, S. A.; Belyaeva, T. L.

2016-11-01

The root mean square radii of 16O in the short-lived 0+ excited states were experimentally deduced for the first time from the analyses of α +16O diffraction scattering. Differential cross sections of the elastic and inelastic α +16O and 16O+16O scattering in the incident energy range from a few MeV/nucleon up to 100 MeV/nucleon were analyzed by the modified diffraction model. No significant radius enhancement in any state in comparison with the ground state was observed. This concerns, in particular, the 15.1-MeV 06+ state of 16O, located in the vicinity of the four-α -particle complete dissociation threshold, for which we did not confirm the "gigantic" size predicted by the α -particle condensation model. This result does not support the idea that 16O in the 06+ state has a dilute structure and can be considered as an analog of the famous 7.65-MeV 02+ Hoyle state of 12C.

Statistical mechanical models for dissociative adsorption of O2 on metal(100) surfaces with blocking, steering, and funneling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, James W.; Liu, Da-Jiang

We develop statistical mechanical models amenable to analytic treatment for the dissociative adsorption of O2 at hollow sites on fcc(100) metal surfaces. The models incorporate exclusion of nearest-neighbor pairs of adsorbed O. However, corresponding simple site-blocking models, where adsorption requires a large ensemble of available sites, exhibit an anomalously fast initial decrease in sticking. Thus, in addition to blocking, our models also incorporate more facile adsorption via orientational steering and funneling dynamics (features supported by ab initio Molecular Dynamics studies). Behavior for equilibrated adlayers is distinct from those with finite adspecies mobility. We focus on the low-temperature limited-mobility regime wheremore » analysis of the associated master equations readily produces exact results for both short- and long-time behavior. Kinetic Monte Carlo simulation is also utilized to provide a more complete picture of behavior. These models capture both the initial decrease and the saturation of the experimentally observed sticking versus coverage, as well as features of non-equilibrium adlayer ordering as assessed by surface-sensitive diffraction.« less

Statistical mechanical models for dissociative adsorption of O{sub 2} on metal(100) surfaces with blocking, steering, and funneling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, James W.; Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011; Liu, Da-Jiang

We develop statistical mechanical models amenable to analytic treatment for the dissociative adsorption of O{sub 2} at hollow sites on fcc(100) metal surfaces. The models incorporate exclusion of nearest-neighbor pairs of adsorbed O. However, corresponding simple site-blocking models, where adsorption requires a large ensemble of available sites, exhibit an anomalously fast initial decrease in sticking. Thus, in addition to blocking, our models also incorporate more facile adsorption via orientational steering and funneling dynamics (features supported by ab initio Molecular Dynamics studies). Behavior for equilibrated adlayers is distinct from those with finite adspecies mobility. We focus on the low-temperature limited-mobility regimemore » where analysis of the associated master equations readily produces exact results for both short- and long-time behavior. Kinetic Monte Carlo simulation is also utilized to provide a more complete picture of behavior. These models capture both the initial decrease and the saturation of the experimentally observed sticking versus coverage, as well as features of non-equilibrium adlayer ordering as assessed by surface-sensitive diffraction.« less

Dissociation coefficients of protein adsorption to nanoparticles as quantitative metrics for description of the protein corona: A comparison of experimental techniques and methodological relevance.

PubMed

Hühn, Jonas; Fedeli, Chiara; Zhang, Qian; Masood, Atif; Del Pino, Pablo; Khashab, Niveen M; Papini, Emanuele; Parak, Wolfgang J

2016-06-01

Protein adsorption to nanoparticles is described as a chemical reaction in which proteins attach to binding sites on the nanoparticle surface. This process is defined by a dissociation coefficient, which tells how many proteins are adsorbed per nanoparticle in dependence of the protein concentration. Different techniques to experimentally determine dissociation coefficients of protein adsorption to nanoparticles are reviewed. Results of more than 130 experiments in which dissociation coefficients have been determined are compared. Data show that different methods, nanoparticle systems, and proteins can lead to significantly different dissociation coefficients. However, we observed a clear tendency of smaller dissociation coefficients upon less negative towards more positive zeta potentials of the nanoparticles. The zeta potential thus is a key parameter influencing protein adsorption to the surface of nanoparticles. Our analysis highlights the importance of the characterization of the parameters governing protein-nanoparticle interaction for quantitative evaluation and objective literature comparison. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simulating the effect of hydrate dissociation on wellhead stability during oil and gas development in deepwater

NASA Astrophysics Data System (ADS)

Li, Qingchao; Cheng, Yuanfang; Zhang, Huaiwen; Yan, Chuanliang; Liu, Yuwen

2018-02-01

It is well known that methane hydrate has been identified as an alternative resource due to its massive reserves and clean property. However, hydrate dissociation during oil and gas development (OGD) process in deep water can affect the stability of subsea equipment and formation. Currently, there is a serious lack of studies over quantitative assessment on the effects of hydrate dissociation on wellhead stability. In order to solve this problem, ABAQUS finite element software was used to develop a model and to evaluate the behavior of wellhead caused by hydrate dissociation. The factors that affect the wellhead stability include dissociation range, depth of hydrate formation and mechanical properties of dissociated hydrate region. Based on these, series of simulations were carried out to determine the wellhead displacement. The results revealed that, continuous dissociation of hydrate in homogeneous and isotropic formations can causes the non-linear increment in vertical displacement of wellhead. The displacement of wellhead showed good agreement with the settlement of overlying formations under the same conditions. In addition, the shallower and thicker hydrate formation can aggravate the influence of hydrate dissociation on the wellhead stability. Further, it was observed that with the declining elastic modulus and Poisson's ratio, the wellhead displacement increases. Hence, these findings not only confirm the effect of hydrate dissociation on the wellhead stability, but also lend support to the actions, such as cooling the drilling fluid, which can reduce the hydrate dissociation range and further make deepwater operations safer and more efficient.

A general mechanism for competitor-induced dissociation of molecular complexes

PubMed Central

Paramanathan, Thayaparan; Reeves, Daniel; Friedman, Larry J.; Kondev, Jane; Gelles, Jeff

2014-01-01

The kinetic stability of non-covalent macromolecular complexes controls many biological phenomena. Here we find that physical models of complex dissociation predict that competitor molecules will in general accelerate the breakdown of isolated bimolecular complexes by occluding rapid rebinding of the two binding partners. This prediction is largely independent of molecular details. We confirm the prediction with single-molecule fluorescence experiments on a well-characterized DNA strand dissociation reaction. Contrary to common assumptions, competitor–induced acceleration of dissociation can occur in biologically relevant competitor concentration ranges and does not necessarily implyternary association of competitor with the bimolecular complex. Thus, occlusion of complex rebinding may play a significant role in a variety of biomolecular processes. The results also show that single-molecule colocalization experiments can accurately measure dissociation rates despite their limited spatio temporal resolution. PMID:25342513

Dissociative recombination of HCl+

NASA Astrophysics Data System (ADS)

Larson, Åsa; Fonseca dos Santos, Samantha; E. Orel, Ann

2017-08-01

The dissociative recombination of HCl+, including both the direct and indirect mechanisms, is studied. For the direct process, the relevant electronic states are calculated ab initio by combining electron scattering calculations to obtain resonance positions and autoionization widths with multi-reference configuration interaction calculations of the ion and Rydberg states. The cross section for the direct dissociation along electronic resonant states is computed by solution of the time-dependent Schrödinger equation. For the indirect process, an upper bound value for the cross section is obtained using a vibrational frame transformation of the elements of the scattering matrix at energies just above the ionization threshold. Vibrational excitations of the ionic core from the ground vibrational state, v = 0 , to the first three excited vibrational states, v = 1 , v = 2 , and v = 3 , are considered. Autoionization is neglected and the effect of the spin-orbit splitting of the ionic potential energy upon the indirect dissociative recombination cross section is considered. The calculated cross sections are compared to measurements.

Process for analyzing CO.sub.2 in seawater

DOEpatents

Atwater, James E.; Akse, James R.; DeHart, Jeffrey

1997-01-01

The process of this invention comprises providing a membrane for separating CO.sub.2 into a first CO.sub.2 sample phase and a second CO.sub.2 analyte phase. CO.sub.2 is then transported through the membrane thereby separating the CO.sub.2 with the membrane into a first CO.sub.2 sample phase and a second CO.sub.2 analyte liquid phase including an ionized, conductive, dissociated CO.sub.2 species. Next, the concentration of the ionized, conductive, dissociated CO.sub.2 species in the second CO.sub.2 analyte liquid phase is chemically amplified using a water-soluble chemical reagent which reversibly reacts with undissociated CO.sub.2 to produce conductivity changes therein corresponding to fluctuations in the partial pressure of CO.sub.2 in the first CO.sub.2 sample phase. Finally, the chemically amplified, ionized, conductive, dissociated CO.sub.2 species is introduced to a conductivity measuring instrument. Conductivity changes in the chemically amplified, ionized, conductive, dissociated CO.sub.2 species are detected using the conductivity measuring instrument.

Dissociative recombination of HCl.

PubMed

Larson, Åsa; Fonseca Dos Santos, Samantha; E Orel, Ann

2017-08-28

The dissociative recombination of HCl + , including both the direct and indirect mechanisms, is studied. For the direct process, the relevant electronic states are calculated ab initio by combining electron scattering calculations to obtain resonance positions and autoionization widths with multi-reference configuration interaction calculations of the ion and Rydberg states. The cross section for the direct dissociation along electronic resonant states is computed by solution of the time-dependent Schrödinger equation. For the indirect process, an upper bound value for the cross section is obtained using a vibrational frame transformation of the elements of the scattering matrix at energies just above the ionization threshold. Vibrational excitations of the ionic core from the ground vibrational state, v = 0, to the first three excited vibrational states, v = 1, v = 2, and  v = 3, are considered. Autoionization is neglected and the effect of the spin-orbit splitting of the ionic potential energy upon the indirect dissociative recombination cross section is considered. The calculated cross sections are compared to measurements.

Edge reactivity and water-assisted dissociation on cobalt oxide nanoislands

DOE PAGES

Fester, J.; García-Melchor, M.; Walton, A. S.; ...

2017-01-30

Here, transition metal oxides show great promise as Earth-abundant catalysts for the oxygen evolution reaction in electrochemical water splitting. However, progress in the development of highly active oxide nanostructures is hampered by a lack of knowledge of the location and nature of the active sites. Here we show, through atom-resolved scanning tunnelling microscopy, X-ray spectroscopy and computational modelling, how hydroxyls form from water dissociation at under coordinated cobalt edge sites of cobalt oxide nanoislands. Surprisingly, we find that an additional water molecule acts to promote all the elementary steps of the dissociation process and subsequent hydrogen migration, revealing the importantmore » assisting role of a water molecule in its own dissociation process on a metal oxide. Inspired by the experimental findings, we theoretically model the oxygen evolution reaction activity of cobalt oxide nanoislands and show that the nanoparticle metal edges also display favourable adsorption energetics for water oxidation under electrochemical conditions.« less

Infrared laser dissociation of single megadalton polymer ions in a gated electrostatic ion trap: the added value of statistical analysis of individual events.

PubMed

Halim, Mohammad A; Clavier, Christian; Dagany, Xavier; Kerleroux, Michel; Dugourd, Philippe; Dunbar, Robert C; Antoine, Rodolphe

2018-05-07

In this study, we report the unimolecular dissociation mechanism of megadalton SO 3 -containing poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) polymer cations and anions with the aid of infrared multiphoton dissociation coupled to charge detection ion trap mass spectrometry. A gated electrostatic ion trap ("Benner trap") is used to store and detect single gaseous polymer ions generated by positive and negative polarity in an electrospray ionization source. The trapped ions are then fragmented due to the sequential absorption of multiple infrared photons produced from a continuous-wave CO 2 laser. Several fragmentation pathways having distinct signatures are observed. Highly charged parent ions characteristically adopt a distinctive "stair-case" pattern (assigned to the "fission" process) whereas low charge species take on a "funnel like" shape (assigned to the "evaporation" process). Also, the log-log plot of the dissociation rate constants as a function of laser intensity between PAMPS positive and negative ions is significantly different.

CO2 hydrate: Synthesis, composition, structure, dissociation behavior, and a comparison to structure I CH4 hydrate

USGS Publications Warehouse

Circone, S.; Stern, L.A.; Kirby, S.H.; Durham, W.B.; Chakoumakos, B.C.; Rawn, C.J.; Rondinone, A.J.; Ishii, Y.

2003-01-01

Structure I (sI) carbon dioxide (CO2) hydrate exhibits markedly different dissociation behavior from sI methane (CH4) hydrate in experiments in which equilibrated samples at 0.1 MPa are heated isobarically at 13 K/h from 210 K through the H2O melting point (273.15 K). The CO2 hydrate samples release only about 3% of their gas content up to temperatures of 240 K, which is 22 K above the hydrate phase boundary. Up to 20% is released by 270 K, and the remaining CO2 is released at 271.0 plusmn; 0.5 K, where the sample temperature is buffered until hydrate dissociation ceases. This reproducible buffering temperature for the dissociation reaction CO2??nH2O = CO2(g) + nH2O(1 to s) is measurably distinct from the pure H2O melting point at 273.15 K, which is reached as gas evolution ceases. In contrast, when si CH4 hydrate is heated at the same rate at 0.1 MPa, >95% of the gas is released within 25 K of the equilibrium temperature (193 K at 0.1 MPa). In conjunction with the dissociation study, a method for efficient and reproducible synthesis of pure polycrystalline CO2 hydrate with suitable characteristics for material properties testing was developed, and the material was characterized. CO2 hydrate was synthesized from CO2 liquid and H2O solid and liquid reactants at pressures between 5 and 25 MPa and temperatures between 250 and 281 K. Scanning electron microscopy (SEM) examination indicates that the samples consist of dense crystalline hydrate and 50-300 ??m diameter pores that are lined with euhedral cubic hydrate crystals. Deuterated hydrate samples made by this same procedure were analyzed by neutron diffraction at temperatures between 4 and 215 K; results confirm that complete conversion of water to hydrate has occurred and that the measured unit cell parameter and thermal expansion are consistent with previously reported values. On the basis of measured weight gain after synthesis and gas yields from the dissociation experiments, approximately all cages in the hydrate structure are filled such that n ??? 5.75.

Tandem mass spectrometry of nitric oxide and hydrogen sulfide releasing aspirins: a hint into activity behavior.

PubMed

Crestoni, Maria Elisa; Chiavarino, Barbara; Guglielmo, Stefano; Lilla, Valentina; Fornarini, Simonetta

2013-01-01

Aspirin (acetylsalicylic acid, ASA) is the most popular non-steroidal anti-inflammatory drug. However, due to its action on cyclooxygenase and its acid nature, aspirin is associated with adverse gastrointestinal effects. In an effort to minimize these side effects, NO-donor and H2S-donor ASA co-drugs have been designed and tested. Their mass spectrometric behavior is now analyzed and reported. Positive ions were obtained by electrospray ionization involving protonation or alkali metal attachment. Their dissociation processes have been studied by collision induced dissociation in a triple quadrupole instrument. High mass accuracy measurements have been recorded on a Fourier transform ion cyclotron resonance mass spectrometer. The protonated molecules dissociate by an exclusive or largely prevailing path leading to acetyloxy-substituted benzoyl cation, namely an ASA unit. The process is reminiscent of the enzymatic hydrolysis, releasing intact ASA to a large extent. Only at higher collision energy does the formal ketene loss disrupt the ASA moiety. The gas phase chemistry of protonated ASA-releasing drugs develops along elementary dissociation steps analogous to the reactive processes in complex biological environments. This notion may provide a tool for preliminary testing of new compounds.

Influence of surface vacancy defects on the carburisation of Fe 110 surface by carbon monoxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakrabarty, Aurab, E-mail: aurab.chakrabarty@qatar.tamu.edu; Bouhali, Othmane; Mousseau, Normand

Adsorption and dissociation of gaseous carbon monoxide (CO) on metal surfaces is one of the most frequently occurring processes of carburisation, known as primary initiator of metal dusting corrosion. Among the various factors that can significantly influence the carburisation process are the intrinsic surface defects such as single surface vacancies occurring at high concentrations due to their low formation energy. Intuitively, adsorption and dissociation barriers of CO are expected to be lowered in the vicinity of a surface vacancy, due to the strong attractive interaction between the vacancy and the C atom. Here the adsorption energies and dissociation pathways ofmore » CO on clean and defective Fe 110 surface are explored by means of density functional theory. Interestingly, we find that the O adatom, resulting from the CO dissociation, is unstable in the electron-deficit neighbourhood of the vacancy due to its large electron affinity, and raises the barrier of the carburisation pathway. Still, a full comparative study between the clean surface and the vacancy-defected surface reveals that the complete process of carburisation, starting from adsorption to subsurface diffusion of C, is more favourable in the vicinity of a vacancy defect.« less

Causes of dissociation between subjective workload measures and performance - Caveats for the use of subjective assessments

NASA Technical Reports Server (NTRS)

Vidulich, M. A.; Wickens, C. D.

1985-01-01

Dissociations between subjective workload assessments and performance were investigated. The difficulty of a Sternberg memory search task was manipulated by varying stimulus presentation rate, stimulus discernibility, value of good performance, and automaticity of performance. All Sternberg task conditions were performed both alone and concurrently with a tracking task. Bipolar subjective workload assessments were collected. Dissociations between workload and performance were found related to automaticity, presentation rate, and motivation level. The results were interpreted as supporting the hypothesis that the specific cognitive processes responsible for subjective assessments can differ from those responsible for performance. The potential contamination these dissociations could inflict on operational workload assessments is discussed.

Electron-temperature dependence of dissociative recombination of electrons with N2/+/.N2 dimer ions

NASA Technical Reports Server (NTRS)

Whitaker, M.; Biondi, M. A.; Johnsen, R.

1981-01-01

The variation with electron temperature of the dissociative recombination of electrons with N2(+).N2 dimer ions is investigated in light of the importance of such ions in the lower ionosphere and in laser plasmas. Dissociative recombination coefficients were determined by means of a microwave afterglow mass spectrometer technique for electron temperatures from 300-5600 K and an ion and neutral temperature of 300 K. The recombination coefficient is found to be proportional to the -0.41 power of the electron temperature in this range, similar to that observed for the CO(+).CO dimer ion and consistent with the expected energy dependence for a fast dissociative process.

Repressed ghosts and dissociated vampires in the enacted dimension of psychoanalytic treatment.

PubMed

Katz, Gil

2015-04-01

One of the most evocative uses of the metaphor of a ghost in psychoanalytic writing was crafted by Hans Loewald in "On the Therapeutic Action of Psycho-Analysis" (1960). In this seminal work, Loewald likened the process of psychoanalytic change to that of transforming psychic ghosts into ancestors. In the present paper, the author supplements the metaphor of ghosts that haunt with the metaphor of vampires that menace, and links these two alien experiences to two psychological processes: repression and dissociation. Descriptions of ghosts and vampires in folklore, and the ways they are experienced in analytic treatment, are followed by an explication of the enacted dimension of analytic process-the arena of treatment in which all demons are inevitably revivified, "recognized," and ultimately laid to rest. The paper includes a clinical illustration of a dissociated vampire: a Holocaust trauma transmitted across three generations of survivors. © 2015 The Psychoanalytic Quarterly, Inc.

[Processes of logical thought in a case of cerebral vascular lesion].

PubMed

Blanco Men ndez, R; Aguado Balsas, A M

Reasoning and logical thought processes have traditionally been attributed to frontal lobe function or,on the other hand, have been considered as diffuse functions of the brain. However, there is today evidence enough about the possibility to find dissociations in thought processes, depending on logical structure of the experimental tasks and referring to different areas of the brain, frontal and post rolandic ones. To study possible dissociations between thought structures corresponding to categorical and relational logic, on one hand, and propositional logic on the other hand. The case of a brain injured patient with vascular etiology, localized in left frontal parietal cortex, is presented. A specific battery of reasoning tests has been administered. . A differential performance at some reasoning experimental tasks has been found depending on such logical conceptual structures. The possibility of establishing dissociations among certain logical thought and intelectual functions depending on localization of possible brain lesion (frontal versus temporal) is discussed.

Dissociative identity disorder and prepulse inhibition of the acoustic startle reflex

PubMed Central

Dale, Karl Yngvar; Flaten, Magne Arve; Elden, Åke; Holte, Arne

2008-01-01

A group of persons with dissociative identity disorder (DID) was compared with a group of persons with other dissociative disorders, and a group of nondiagnosed controls with regard to prepulse inhibition (PPI) of the acoustic startle reflex. The findings suggest maladaptive attentional processes at a controlled level, but not at a preattentive automatic level, in persons with DID. The prepulse occupied more controlled attentional resources in the DID group compared with the other two groups. Preattentive automatic processing, on the other hand, was normal in the DID group. Moreover, startle reflexes did not habituate in the DID group. In conclusion, increased PPI and delayed habituation is consistent with increased vigilance in individuals with DID. The present findings of reduced habituation of startle reflexes and increased PPI in persons with DID suggest the operation of a voluntary process that directs attention away from unpleasant or threatening stimuli. Aberrant voluntary attentional processes may thus be a defining characteristic in DID. PMID:18830396

The Association among Childhood Trauma, Pathological Dissociation and Gambling Severity in Casino Gamblers.

PubMed

Imperatori, Claudio; Innamorati, Marco; Bersani, Francesco Saverio; Imbimbo, Francesca; Pompili, Maurizio; Contardi, Anna; Farina, Benedetto

2017-01-01

The aim of the present study was to explore the role of pathological dissociation in mediating the association between childhood trauma (CT) and gambling severity. One hundred seventy-one (134 men and 37 women) gamblers recruited in gambling environments (i.e., two Italian casinos) have been enrolled in the study. Psychopathological assessments included the Childhood Trauma Questionnaire (CTQ), the Dissociative Experiences Scale-Taxon (DES-T), the South Oaks Gambling Screen (SOGS), the CAGE and the Hospital Anxiety and Depression Scale. A mediational model, analyzing the direct and indirect effects of CTQ on SOGS through the mediating role of DES-T, showed that the relation between CTQ and SOGS was fully mediated by DES-T scores (b = 0.07; se = 0.15; p < 0.001). This finding raises the possibility that CT explains gambling severity through the presence of pathological dissociative symptoms and dissociative pathogenetic processes. Copyright © 2015 John Wiley & Sons, Ltd. Gambling severity is associated with both childhood trauma and pathological dissociation in casino gamblers. A mediational model shows that the effect of childhood trauma on gambling severity is entirely mediated by pathological dissociation. From a clinical point of view, our results highlight the importance of assessing, and possibly treating, dissociative symptoms in individuals with gambling disorder. Copyright © 2015 John Wiley & Sons, Ltd.

What Hinders Electron Transfer Dissociation (ETD) of DNA Cations?

NASA Astrophysics Data System (ADS)

Hari, Yvonne; Leumann, Christian J.; Schürch, Stefan

2017-12-01

Radical activation methods, such as electron transfer dissociation (ETD), produce structural information complementary to collision-induced dissociation. Herein, electron transfer dissociation of 3-fold protonated DNA hexamers was studied to gain insight into the fragmentation mechanism. The fragmentation patterns of a large set of DNA hexamers confirm cytosine as the primary target of electron transfer. The reported data reveal backbone cleavage by internal electron transfer from the nucleobase to the phosphate linker leading either to a•/ w or d/ z• ion pairs. This reaction pathway contrasts with previous findings on the dissociation processes after electron capture by DNA cations, suggesting multiple, parallel dissociation channels. However, all these channels merely result in partial fragmentation of the precursor ion because the charge-reduced DNA radical cations are quite stable. Two hypotheses are put forward to explain the low dissociation yield of DNA radical cations: it is either attributed to non-covalent interactions between complementary fragments or to the stabilization of the unpaired electron in stacked nucleobases. MS3 experiments suggest that the charge-reduced species is the intact oligonucleotide. Moreover, introducing abasic sites significantly increases the dissociation yield of DNA cations. Consequently, the stabilization of the unpaired electron by π-π-stacking provides an appropriate rationale for the high intensity of DNA radical cations after electron transfer. [Figure not available: see fulltext.

Foveated Wide Field-of-View Imaging for Missile Warning/Tracking using Adaptive Optics

DTIC Science & Technology

2007-11-30

their melting temperatures are relatively high because of their long molecular conjugation. To lower the melting points, we have formulated eutectic ...compounds during recrystallization processes. 3. Polar, partially dissociated like organic acids, phenols or bases. Their dissociation level depends on the

Characterizations of GaN film growth by ECR plasma chemical vapor deposition

NASA Astrophysics Data System (ADS)

Fu, Silie; Chen, Junfang; Zhang, Hongbin; Guo, Chaofen; Li, Wei; Zhao, Wenfen

2009-06-01

The electron cyclotron resonance plasma-enhanced metalorganic chemical vapor deposition technology (ECR-MOPECVD) is adopted to grow GaN films on (0 0 0 1) α-Al2O3 substrate. The gas sources are pure N2 and trimethylgallium (TMG). Optical emission spectroscopy (OES) and thermodynamic analysis of GaN growth are applied to understand the GaN growth process. The OES of ECR plasma shows that TMG is significantly dissociated in ECR plasma. Reactants N and Ga in the plasma, obtained easily under the self-heating condition, are essential for the GaN growth. They contribute to the realization of GaN film growth at a relatively low temperature. The thermodynamic study shows that the driving force for the GaN growth is high when N2:TMG>1. Furthermore, higher N2:TMG flow ratio makes the GaN growth easier. Finally, X-ray diffraction, photoluminescence, and atomic force microscope are applied to investigate crystal quality, morphology, and roughness of the GaN films. The results demonstrate that the ECR-MOPECVD technology is favorable for depositing GaN films at low temperatures.

Synthesis and formation mechanism of pinnoite in sulfated-type boron concentrated brine by dilution method

NASA Astrophysics Data System (ADS)

Peng, Jiaoyu; Bian, Shaoju; Lin, Feng; Wang, Liping; Dong, Yaping; Li, Wu

2017-10-01

The synthesis of pinnoite (MgB2O(OH)6) in boron-containing brine was established with a novel dilution method. Effects of temperature, precipitation time, boron concentration and mass dilution ratio on the formation of pinnoite were investigated. The products obtained were characterized by X-ray diffraction (XRD), Raman, thermogravimetric and differential scanning calorimeter (TG-DSC), and scanning electron microscopy. The transformation mechanism of pinnoite with different dilution ratios was assumed by studying the crystal growth of pinnoite. The results showed that pinnoite was synthesized above 60 °C in the diluted brine. There were two reaction steps - precipitation of amorphous solid and the formation of pinnoite crystals - during the whole reaction process of pinnoite when the dilution ratio is more than 1.0 at 80 °C. While in the 0.5 diluted brine, only one reaction step of pinnoite crystal formation was observed and its transformation mechanism was discussed based on dissociation of polyborates in brine. Besides, the origin of pinnoite mineral deposited on salt lake bottom was proposed.

Dissociative recombination in interstellar clouds

NASA Technical Reports Server (NTRS)

Black, John H.; Van Dishoeck, Ewine F.

1989-01-01

Molecular ions play a significant role in the chemistry and evolution of interstellar molecular clouds, even though these regions are overwhelmingly neutral. The dissociative recombination (DR) process governs the abundances of many of these ions and of related neutral species. The gas-phase ion-molecule chemistry of the simplest species is summarized, with emphasis on those problems which are most sensitive to uncertain rates or product branching ratios of DR processes. Examples of the kinds of information needed about DR processes are presented. The importance of the H3(+) ion and prospects for its direct observation are discussed.

Interaction of SO2 and CO with the Ti2O3(101¯2) surface

NASA Astrophysics Data System (ADS)

Smith, Kevin E.; Henrich, Victor E.

1985-10-01

The interaction of sulfur dioxide with the nearly perfect (101¯2) surface of the corundum transition-metal oxide Ti2O3 has been studied using ultraviolet and x-ray photoemission spectroscopies and low-energy electron diffraction. The reaction of SO2 with Ti2O3 is found to be extremely vigorous, with SO2 adsorbing dissociatively and catalyzing the complete oxidation of the surface to TiO2 and TiS2. This result is significant since exposure to large amounts of O2 does not result in the production of large amounts of TiO2 at the Ti2O3 surface. Dissociative adsorption of SO2 continues for exposures up to at least 104 L (1 L=10-6Torr sec). The reaction is accompanied by large scale surface disorder and by an increase in the work function of 1.32 eV. In contrast, CO adsorbs molecularly for exposures >=105 L, with an extramolecular relaxation-polarization shift of 3.0 eV. For CO exposures <=104 L, the chemisorption mechanism is tentatively identified as dissociative adsorption at defect sites. Inclusive of this study, the interaction of four oxygen-containing molecules (SO2, CO, H2O, and O2) with Ti2O3(101¯2) surfaces has been studied, and their behavior is compared and trends isolated with a view to understanding the oxidation of Ti2O3.

Calculation of rates of exciton dissociation into hot charge-transfer states in model organic photovoltaic interfaces

NASA Astrophysics Data System (ADS)

Vázquez, Héctor; Troisi, Alessandro

2013-11-01

We investigate the process of exciton dissociation in ordered and disordered model donor/acceptor systems and describe a method to calculate exciton dissociation rates. We consider a one-dimensional system with Frenkel states in the donor material and states where charge transfer has taken place between donor and acceptor. We introduce a Green's function approach to calculate the generation rates of charge-transfer states. For disorder in the Frenkel states we find a clear exponential dependence of charge dissociation rates with exciton-interface distance, with a distance decay constant β that increases linearly with the amount of disorder. Disorder in the parameters that describe (final) charge-transfer states has little effect on the rates. Exciton dissociation invariably leads to partially separated charges. In all cases final states are “hot” charge-transfer states, with electron and hole located far from the interface.

Multiple exciton dissociation in CdSe quantum dots by ultrafast electron transfer to adsorbed methylene blue.

PubMed

Huang, Jier; Huang, Zhuangqun; Yang, Ye; Zhu, Haiming; Lian, Tianquan

2010-04-07

Multiexciton generation in quantum dots (QDs) may provide a new approach for improving the solar-to-electric power conversion efficiency in QD-based solar cells. However, it remains unclear how to extract these excitons before the ultrafast exciton-exciton annihilation process. In this study we investigate multiexciton dissociation dynamics in CdSe QDs adsorbed with methylene blue (MB(+)) molecules by transient absorption spectroscopy. We show that excitons in QDs dissociate by ultrafast electron transfer to MB(+) with an average time constant of approximately 2 ps. The charge separated state is long-lived (>1 ns), and the charge recombination rate increases with the number of dissociated excitons. Up to three MB(+) molecules per QD can be reduced by exciton dissociation. Our result demonstrates that ultrafast interfacial charge separation can effectively compete with exciton-exciton annihilation, providing a viable approach for utilizing short-lived multiple excitons in QDs.

Domain-Specific Control Mechanisms for Emotional and Nonemotional Conflict Processing

ERIC Educational Resources Information Center

Soutschek, Alexander; Schubert, Torsten

2013-01-01

Recent neuroimaging studies suggest that the human brain activates dissociable cognitive control networks in response to conflicts arising within the cognitive and the affective domain. The present study tested the hypothesis that nonemotional and emotional conflict regulation can also be dissociated on a functional level. For that purpose, we…

Dissociation reactions of potassiated glucose: deionization, potassium hydroxide loss, and cross-ring dissociation

NASA Astrophysics Data System (ADS)

Dyakov, Y. A.; Kazaryan, M. A.; Golubkov, M. G.; Gubanova, D. P.; Asratyan, A. A.

2018-04-01

Photochemical properties of carbohydrates, including mono- and polysaccharides, as well as various kinds of glycoproteins, proteoglycans, and glycolipids, take great attention last decades due to their significance for clarifying physical and chemical processes happening in biological molecules under irradiation. Understanding of excitation and ionization processes is important for interpretation of mass spectrometric (MS) experiments, which is the main instrument for quick and reliable analysis of biological samples. While polynucleotides and simple proteins can be easily studied by standard MS techniques (MALDI, ESI, and CID), carbohydrates and complicated biomolecules containing oligosaccharide residues are difficult to be ionized. Carbohydrates give a low signal yield. Their detection and analysis requires the special equipment and technology. Therefore, the development of new efficient methods for identification of carbohydrates in biological samples currently is the critical scientific and technical problem. In this work we study dissociation processes taking place in potassiated α- and β-glucose, which can be concerned as the modelling molecule for investigation of wide range of carbohydrates and carbohydrate fragments of biomolecules containing potassium ion as the ionization source. Here we compare deionization process with H2O and KOH elimination channels, as far as their competition with cross-ring dissociation processes. Potential energy surface were optimized by the density functional B3LYP/6-31G* method. Single point energy calculations in minima and transition state points were performed by G3(MP2,CCSD) ab initio method.

Electro-Optical Properties of Hydrogenated Si-Doped CdO

NASA Astrophysics Data System (ADS)

Dakhel, A. A.

2018-01-01

The optoelectronic properties of CdO films could be controlled and improved for transparent conducting (TC) purposes by means of doping. In the present work, several sets of CdO thin films hydrogenated and doped with different amounts of silicon were prepared on glass substrates by a thermal deposition technique in order to improve their TC properties. The x-ray diffraction method was used to study the crystal structural variations in CdO films as a consequence of Si(H) doping. Optical properties were studied by means of optical absorption and reflection spectroscopy. The observed blue-shifting in the optical bandgap by Si(H) doping was attributed to the Moss-Burstein effect with reduced structural bandgap by point defects created during the process of doping. The mechanism of the hydrogenation process was explained by the dissociation of hydrogen molecules into atoms/ions, which in turn interacted with structural oxygen ions leading to the creation of oxygen vacancies. The creation of oxygen vacancies caused increases in electron concentration ( N el) and electrical conductivity ( σ). The results showed that Si(H) doping of host CdO films significantly increased their conductivity, mobility, and carrier concentration by ˜ 69, 5.6, and 12.3 times, respectively. The results confirm that Si(H) doping is effective for using CdO films in transparent conducting oxide applications.

Performance assessment of low pressure nuclear thermal propulsion

NASA Technical Reports Server (NTRS)

Gerrish, Harrold P., Jr.; Doughty, Glen E.

1993-01-01

An increase in Isp for nuclear thermal propulsion systems is desirable for reducing the propellant requirements and cost of future applications, such as the Mars Transfer Vehicle. Several previous design studies have suggested that the Isp could be increased substantially with hydrogen dissociation/recombination. Hydrogen molecules (H2), at high temperatures and low pressures, will dissociate to monatomic hydrogen (H). The reverse process (i.e., formation of H2 from H) is exothermic. The exothermic energy in a nozzle increases the kinetic energy and therefore, increases the Isp. The low pressure nuclear thermal propulsion system (LPNTP) system is expected to maximize the hydrogen dissociation/recombination and Isp by operating at high chamber temperatures and low chamber pressures. The process involves hydrogen flow through a high temperature, low pressure fission reactor, and out a nozzle. The high temperature (approximately 3000 K) of the hydrogen in the reactor is limited by the temperature limits of the reactor material. The minimum chamber pressure is about 1 atm because lower pressures decrease the engines thrust to weight ratio below acceptable limits. This study assumes that hydrogen leaves the reactor and enters the nozzle at the 3000 K equilibrium dissociation level. Hydrogen dissociation in the reactor does not affect LPNTP performance like dissociation in traditional chemical propulsion systems, because energy from the reactor resupplies energy lost due to hydrogen dissociation. Recombination takes place in the nozzle due primarily to a drop in temperature as the Mach number increases. However, as the Mach number increases beyond the nozzle throat, the static pressure and density of the flow decreases and minimizes the recombination. The ideal LPNTP Isp at 3000 K and 10 psia is 1160 seconds due to the added energy from fast recombination rates. The actual Isp depends on the finite kinetic reaction rates which affect the amount of monatomic hydrogen recombination before the flow exits the nozzle. A LPNTP system has other technical issues (e.g. flow instability and two-phase flow) besides hydrogen dissociation/recombination which affect the systems practicality. In this study, only the effects of hydrogen dissociation/recombination are examined.

Combustion of Methane Hydrate

NASA Astrophysics Data System (ADS)

Roshandell, Melika

A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding from the experimental component of the research was that hydrates can burn completely, and that they burn most rapidly just after ignition and then burn steadily when some of the water in the dissociated zone is allowed to drain away. Excessive surfactant in the water creates a foam layer around the hydrate that acts as an insulator. The layer prevents sufficient heat flux from reaching the hydrate surface below the foam to release additional methane and the hydrate flame extinguishes. No self-healing or ice-freezing processes were observed in any of the combustion experiments. There is some variability, but a typical hydrate flame is receiving between one and two moles of water vapor from the liquid dissociated zone of the hydrate for each mole of methane it receives from the dissociating solid region. This limits the flame temperature to approximately 1800 K. In the theoretical portion of the study, a physical model using an energy balance from methane combustion was developed to understand the energy transfer between the three phases of gas, liquid and solid during the hydrate burn. Also this study provides an understanding of the different factors impacting the hydrate's continuous burn, such as the amount of water vapor in the flame. The theoretical study revealed how the water layer thickness on the hydrate surface, and its effect on the temperature gradient through the dissociated zone, plays a significant role in the hydrate dissociation rate and methane release rate. Motivated by the above mentioned observation from the theoretical analysis, a 1-D two-phase numerical simulation based on a moving front model for hydrate dissociation from a thermal source was developed. This model was focused on the dynamic growth of the dissociated zone and its effect on the dissociation rate. The model indicated that the rate of hydrate dissociation with a thermal source is a function of the dissociated zone thickness. It shows that in order for a continuous dissociation and methane release, some of the water from the dissociated zone needs to be drained. The results are consistent with the experimental observations. The understanding derived from the experiments and the numerical model permitted a brief exploration into the potential effects of pressure on the combustion of methane hydrates. The prediction is that combustion should improve under high pressure conditions because the evaporation of water is suppressed allowing more energy into the dissociation. Future experiments are needed to validate these initial findings.

Exact and conceptual repetition dissociate conceptual memory tests: problems for transfer appropriate processing theory.

PubMed

McDermott, K B; Roediger, H L

1996-03-01

Three experiments examined whether a conceptual implicit memory test (specifically, category instance generation) would exhibit repetition effects similar to those found in free recall. The transfer appropriate processing account of dissociations among memory tests led us to predict that the tests would show parallel effects; this prediction was based upon the theory's assumption that conceptual tests will behave similarly as a function of various independent variables. In Experiment 1, conceptual repetition (i.e., following a target word [e.g., puzzles] with an associate [e.g., jigsaw]) did not enhance priming on the instance generation test relative to the condition of simply presenting the target word once, although this manipulation did affect free recall. In Experiment 2, conceptual repetition was achieved by following a picture with its corresponding word (or vice versa). In this case, there was an effect of conceptual repetition on free recall but no reliable effect on category instance generation or category cued recall. In addition, we obtained a picture superiority effect in free recall but not in category instance generation. In the third experiment, when the same study sequence was used as in Experiment 1, but with instructions that encouraged relational processing, priming on the category instance generation task was enhanced by conceptual repetition. Results demonstrate that conceptual memory tests can be dissociated and present problems for Roediger's (1990) transfer appropriate processing account of dissociations between explicit and implicit tests.

X-ray-induced dissociation of H.sub.2O and formation of an O.sub.2-H.sub.2 alloy at high pressure

DOEpatents

Mao, Ho-kwang [Washington, DC; Mao, Wendy L [Washington, DC

2011-11-29

A novel molecular alloy of O.sub.2 and H.sub.2 and a method of producing such a molecular alloy are provided. When subjected to high pressure and extensive x-radiation, H.sub.2O molecules cleaved, forming O--O and H--H bonds. In the method of the present invention, the O and H framework in ice VII was converted into a molecular alloy of O.sub.2 and H.sub.2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrate that this crystalline solid differs from previously known phases.

Quantum lithography beyond the diffraction limit via Rabi-oscillations

NASA Astrophysics Data System (ADS)

Liao, Zeyang; Al-Amri, Mohammad; Zubairy, M. Suhail

2011-03-01

We propose a quantum optical method to do the sub-wavelength lithography. Our method is similar to the traditional lithography but adding a critical step before dissociating the chemical bound of the photoresist. The subwavelength pattern is achieved by inducing the multi-Rabi-oscillation between the two atomic levels. The proposed method does not require multiphoton absorption and the entanglement of photons. This method is expected to be realizable using current technology. This work is supported by a grant from the Qatar National Research Fund (QNRF) under the NPRP project and a grant from the King Abdulaziz City for Science and Technology (KACST).

Convergent paradigms for visual neuroscience and dissociative identity disorder.

PubMed

Manning, Mark L; Manning, Rana L

2009-01-01

Although dissociative identity disorder, a condition in which multiple individuals appear to inhabit a single body, is a recognized psychiatric disorder, patients may yet encounter health professionals who declare that they simply "do not believe in multiple personalities." This article explores the proposal that resistance to the disorder represents a failure to apply an appropriate paradigm from which the disorder should be interpreted. Trauma and sociocognitive explanations of dissociative identity disorder are contrasted. The trauma hypothesis is further differentiated into paradigms in which trauma affects a defense mechanism, and one in which trauma serves to inhibit the normal integration sequence of parallel processes of the self in childhood. This latter paradigm is shown to be broadly consistent with current models of cortical processing in another system, the cortical visual system.

Acting without seeing: eye movements reveal visual processing without awareness.

PubMed

Spering, Miriam; Carrasco, Marisa

2015-04-01

Visual perception and eye movements are considered to be tightly linked. Diverse fields, ranging from developmental psychology to computer science, utilize eye tracking to measure visual perception. However, this prevailing view has been challenged by recent behavioral studies. Here, we review converging evidence revealing dissociations between the contents of perceptual awareness and different types of eye movement. Such dissociations reveal situations in which eye movements are sensitive to particular visual features that fail to modulate perceptual reports. We also discuss neurophysiological, neuroimaging, and clinical studies supporting the role of subcortical pathways for visual processing without awareness. Our review links awareness to perceptual-eye movement dissociations and furthers our understanding of the brain pathways underlying vision and movement with and without awareness. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dissociative recombination of N2/+/ in the ionosphere

NASA Technical Reports Server (NTRS)

Torr, M. R.; Torr, D. G.

1979-01-01

N2(+) ion measurements are examined which were made with the Atmospheric Explorer-C satellite during a phase of solar activity in 1978 that was significantly higher than near the earlier minimum. It is found that the major source of N2(+) is photoionization, rather than charge exchange with O(+) (2D), and that the major loss process above 300 km is dissociative recombination with electrons. A data sample for which the electron temperature (T sub e) covered the range from 1000 to 3400 K is used to evaluate the rate constant, alpha, for the dissociative-recombination process. The results show good agreement with laboratory measurements given by the expression: alpha = 1.8 x 10 to the -7th (T sub e/300) to the -0.39th cu cm/sec.

Acting without seeing: Eye movements reveal visual processing without awareness Miriam Spering & Marisa Carrasco

PubMed Central

Spering, Miriam; Carrasco, Marisa

2015-01-01

Visual perception and eye movements are considered to be tightly linked. Diverse fields, ranging from developmental psychology to computer science, utilize eye tracking to measure visual perception. However, this prevailing view has been challenged by recent behavioral studies. We review converging evidence revealing dissociations between the contents of perceptual awareness and different types of eye movements. Such dissociations reveal situations in which eye movements are sensitive to particular visual features that fail to modulate perceptual reports. We also discuss neurophysiological, neuroimaging and clinical studies supporting the role of subcortical pathways for visual processing without awareness. Our review links awareness to perceptual-eye movement dissociations and furthers our understanding of the brain pathways underlying vision and movement with and without awareness. PMID:25765322

Effects of molecular dissociation on the hydrogen equation of state

NASA Astrophysics Data System (ADS)

Bonev, Stanimir; Schwegler, Eric; Galli, Giulia; Gygi, Francois

2002-03-01

It has been suggested recently(François Gygi and G. Galli, submitted to Phys. Rev. Lett.) that the physical mechanism behind the larger compressibility of liquid deuterium observed in laser shock experiments as compared to ab initio simulations may be related to shock-induced electronic excitations. A possible result of such non-adiabatic processes is hindering of the molecular dissociation. This has motivated us to study the importance of molecular dissociation on the hydrogen equation of state. To this end, we have carried out ab initio molecular dynamics simulations of liquid deuterium where intramolecular dissociation is prevented by the use of bond length contraints. Simulations at both fixed thermodynamic conditions and dynamical simulations of shocked deuterium will be discussed.

Diffracted diffraction radiation and its application to beam diagnostics

NASA Astrophysics Data System (ADS)

Goponov, Yu. A.; Shatokhin, R. A.; Sumitani, K.; Syshchenko, V. V.; Takabayashi, Y.; Vnukov, I. E.

2018-03-01

We present theoretical considerations for diffracted diffraction radiation and also propose an application of this process to diagnosing ultra-relativistic electron (positron) beams for the first time. Diffraction radiation is produced when relativistic particles move near a target. If the target is a crystal or X-ray mirror, diffraction radiation in the X-ray region is expected to be diffracted at the Bragg angle and therefore be detectable. We present a scheme for applying this process to measurements of the beam angular spread, and consider how to conduct a proof-of-principle experiment for the proposed method.

Solar-thermal fluid-wall reaction processing

DOEpatents

Weimer, Alan W.; Dahl, Jaimee K.; Lewandowski, Allan A.; Bingham, Carl; Buechler, Karen J.; Grothe, Willy

2006-04-25

The present invention provides a method for carrying out high temperature thermal dissociation reactions requiring rapid-heating and short residence times using solar energy. In particular, the present invention provides a method for carrying out high temperature thermal reactions such as dissociation of hydrocarbon containing gases and hydrogen sulfide to produce hydrogen and dry reforming of hydrocarbon containing gases with carbon dioxide. In the methods of the invention where hydrocarbon containing gases are dissociated, fine carbon black particles are also produced. The present invention also provides solar-thermal reactors and solar-thermal reactor systems.

Solar-Thermal Fluid-Wall Reaction Processing

DOEpatents

Weimer, A. W.; Dahl, J. K.; Lewandowski, A. A.; Bingham, C.; Raska Buechler, K. J.; Grothe, W.

2006-04-25

The present invention provides a method for carrying out high temperature thermal dissociation reactions requiring rapid-heating and short residence times using solar energy. In particular, the present invention provides a method for carrying out high temperature thermal reactions such as dissociation of hydrocarbon containing gases and hydrogen sulfide to produce hydrogen and dry reforming of hydrocarbon containing gases with carbon dioxide. In the methods of the invention where hydrocarbon containing gases are dissociated, fine carbon black particles are also produced. The present invention also provides solar-thermal reactors and solar-thermal reactor systems.

Subunit interactions in horse spleen apoferritin. Dissociation by extremes of pH

PubMed Central

Crichton, Robert R.; Bryce, Charles F. A.

1973-01-01

1. The dissociation of horse spleen apoferritin as a function of pH was analysed by sedimentation-velocity techniques. The oligomer is stable in the range pH2.8–10.6. Between pH2.8 and 1.6 and 10.6 and 13.0 both oligomer and subunits can be detected. At pH values between 1.6 and 1.0 the subunit is the only species observed, although below pH1.0 aggregation of the subunits to a particle sedimenting much faster than the oligomer occurs. 2. When apoferritin is first dissociated into subunits at low pH values and then dialysed into buffers of pH1.5–5.0, the subunit reassociates to oligomer in the pH range 3.1–4.3. 3. U.v.-difference spectroscopy was used to study conformational changes occurring during the dissociation process. The difference spectrum in acid can be accounted for by the transfer of four to five tyrosine residues/subunit from the interior of the protein into the solvent. This process is reversed on reassociation, but shows the same hysteresis as found by sedimentation techniques. The difference spectrum in alkali is more complex, but is consistent with the deprotonation of tyrosine residues, which appear to have rather high pK values. 4. In addition to the involvement of tyrosine residues in the conformational change at low pH values, spectral evidence is presented that one tryptophan residue/subunit also changes its environment before dissociation and subsequent to reassociation. 5. Analysis of the dissociation and reassociation of apoferritin at low pH values suggests that this is a co-operative process involving protonation and deprotonation of at least two carboxyl functions of rather low intrinsic pK. The dissociation at alkaline pH values does not appear to be co-operative. 6. Of the five tyrosine residues/subunit only one can be nitrated with tetranitromethane. Guanidination of lysine residues results in the modification of seven out of a total of nine residues/subunit. Nine out of the ten arginine residues/subunit react with cyclohexanedione. PMID:4737425

Encoding-related brain activity dissociates between the recollective processes underlying successful recall and recognition: a subsequent-memory study.

PubMed

Sadeh, Talya; Maril, Anat; Goshen-Gottstein, Yonatan

2012-07-01

The subsequent-memory (SM) paradigm uncovers brain mechanisms that are associated with mnemonic activity during encoding by measuring participants' neural activity during encoding and classifying the encoding trials according to performance in the subsequent retrieval phase. The majority of these studies have converged on the notion that the mechanism supporting recognition is mediated by familiarity and recollection. The process of recollection is often assumed to be a recall-like process, implying that the active search for the memory trace is similar, if not identical, for recall and recognition. Here we challenge this assumption and hypothesize - based on previous findings obtained in our lab - that the recollective processes underlying recall and recognition might show dissociative patterns of encoding-related brain activity. To this end, our design controlled for familiarity, thereby focusing on contextual, recollective processes. We found evidence for dissociative neurocognitive encoding mechanisms supporting subsequent-recall and subsequent-recognition. Specifically, the contrast of subsequent-recognition versus subsequent-recall revealed activation in the Parahippocampal cortex (PHc) and the posterior hippocampus--regions associated with contextual processing. Implications of our findings and their relation to current cognitive models of recollection are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Native-language N400 and P600 predict dissociable language-learning abilities in adults

PubMed Central

Qi, Zhenghan; Beach, Sara D.; Finn, Amy S.; Minas, Jennifer; Goetz, Calvin; Chan, Brian; Gabrieli, John D.E.

2018-01-01

Language learning aptitude during adulthood varies markedly across individuals. An individual’s native-language ability has been associated with success in learning a new language as an adult. However, little is known about how native-language processing affects learning success and what neural markers of native-language processing, if any, are related to success in learning. We therefore related variation in electrophysiology during native-language processing to success in learning a novel artificial language. Event-related potentials (ERPs) were recorded while native English speakers judged the acceptability of English sentences prior to learning an artificial language. There was a trend towards a double dissociation between native-language ERPs and their relationships to novel syntax and vocabulary learning. Individuals who exhibited a greater N400 effect when processing English semantics showed better future learning of the artificial language overall. The N400 effect was related to syntax learning via its specific relationship to vocabulary learning. In contrast, the P600 effect size when processing English syntax predicted future syntax learning but not vocabulary learning. These findings show that distinct neural signatures of native-language processing relate to dissociable abilities for learning novel semantic and syntactic information. PMID:27737775

pH dependence of the dissociation of multimeric hemoglobin probed by high hydrostatic pressure.

PubMed

Bispo, Jose A C; Santos, Jose L R; Landini, Gustavo F; Goncalves, Juliana M; Bonafe, Carlos F S

2007-02-01

We investigated the thermodynamic features of the classic alkaline dissociation of multimeric hemoglobin (3.1 MDa) from Glossoscolex paulistus (Annelidea) using high hydrostatic pressure. Light scattering measurements up to microscopic thermodynamic equilibrium indicated a high pH dependency of dissociation and association. Electron microscopy and gel filtration corroborated these findings. The volume change of dissociation decreased in absolute values from -48.0 mL/mol of subunit at pH 6.0 to -19.2 mL/mol at pH 9.0, suggesting a lack of protein interactions under alkaline conditions. Concomitantly, an increase in pH reduced the Gibbs free energy of dissociation from 37.7 to 27.5 kJ/mol of subunit. The stoichiometry of proton release calculated from the pressure-induced dissociation curves was +0.602 mol of H(+)/mol of subunit. These results provide a direct quantification of proton participation in stabilizing the aggregated state of the hemoglobin, and contribute to our understanding of protein-protein interactions and of the surrounding conditions that modulate the process of aggregation.

Enhancement of burning velocity by dissociated oxygen atoms

NASA Astrophysics Data System (ADS)

Akashi, Haruaki; Yoshinaga, Tomokazu; Sasaki, Koichi

2015-09-01

Green technology, such as preventing global warming, has been developed for years. Researches on plasma assisted combustion is one of the technologies and have been done for investigating more efficient combustion, more efficient use of fossil fuel with plasmas or applying electric fields. In the ignition time delay analyses with the dissociated oxygen atoms which is generated by non-equilibrium plasma had significant effect on the ignition time. In this paper, dissociated oxygen could effect on burning velocity or not has been examined using CHEMKIN. As a result, no effect can be seen with dissociation degree of lower than 10-3. But there is an effect on the enhancement of burning velocity with higher degree of 10-3. At the dissociation degree of 5×10-2, the burning velocity is enhanced at a factor of 1.24. And it is found that the distributions of each species in front of preheat zone are completely different. The combustion process is proceeded several steps in advance, and generation of H2O, CO and CO2 can be seen before combustion in higher dissociation case. This work was supported by KAKENHI (22340170).

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

NASA Astrophysics Data System (ADS)

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

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

Molecular Determinants and Bottlenecks in the Dissociation Dynamics of Biotin-Streptavidin.

PubMed

Tiwary, Pratyush

2017-12-07

Biotin-streptavidin is a very popular system used to gain insight into protein-ligand interactions. In its tetrameric form, it is well-known for its exceptionally high kinetic stability, being one of the strongest known noncovalent interactions in nature, and it is heavily used across the biotechnological industry. In this work, we gain understanding of the molecular determinants and bottlenecks in the dissociation of the dimeric biotin-streptavidin system in wild type and with a point mutation. Using recently proposed enhanced sampling methods with full atomistic resolution, we reproduce the experimentally reported effect of the mutation on the dissociation rate. We also answer a longstanding question regarding cause/effect in the coupled events of bond stretching and bond hydration during dissociation and establish that in this system, it is the bond stretching and not hydration which forms the bottleneck in the early parts of the dissociation process. We believe these calculations represent a step forward in the use of atomistic simulations to study pharmacokinetics. An improved understanding of biotin-streptavidin dissociation dynamics should also have direct benefits in biotechnological and nanobiotechnological applications.

Recollection of episodic memory within the medial temporal lobe: behavioural dissociations from other types of memory.

PubMed

Easton, Alexander; Eacott, Madeline J

2010-12-31

In recent years there has been significant debate about whether there is a single medial temporal lobe memory system or dissociable systems for episodic and other types of declarative memory. In addition there has been a similar debate over the dissociability of recollection and familiarity based processes in recognition memory. Here we present evidence from recent work using episodic memory tasks in animals that allows us to explore these issues in more depth. We review studies that demonstrate triple dissociations within the medial temporal lobe, with only the hippocampal system being necessary for episodic memory. Similarly we review behavioural evidence for a dissociation in a task of episodic memory in rats where animals with lesions of the fornix are only impaired at recollection of the episodic memory, not recognition within the same trial. This work, then, supports recent models of dissociable neural systems within the medial temporal lobe but also raises questions for future investigation about the interactions of these medial temporal lobe memory systems with other structures. Copyright © 2009 Elsevier B.V. All rights reserved.

Dissociation of Recombinant Prion Protein Fibrils into Short Protofilaments: Implications for the Endocytic Pathway and Involvement of the N-Terminal Domain

PubMed Central

Qi, Xu; Moore, Roger A.; McGuirl, Michele A.

2012-01-01

Fibril dissociation is necessary for efficient conversion of normal prion protein to its misfolded state and continued propagation into amyloid. Recent studies have revealed that conversion occurs along the endocytic pathway. To better understand the dissociation process, we have investigated the effect of low pH on the stability of recombinant prion fibrils. We show that under conditions that mimic the endocytic environment, amyloid fibrils made from full length prion protein dissociate both laterally and axially to form protofilaments. About 5% of the protofilaments are short enough to be considered soluble and contain ~100–300 monomers per structure; these also retain the biophysical characteristics of the filaments. We propose that protonation of His residues and charge repulsion in the N-terminal domain trigger fibril dissociation. Our data suggest that lysosomes and late endosomes are competent milieus for propagating the misfolded state not only by destabilizing the normal prion protein, but by accelerating fibril dissociation into smaller structures that may act as seeds. PMID:22591453

Specific cationic emission of cisplatin following ionization by swift protons

NASA Astrophysics Data System (ADS)

Moretto-Capelle, Patrick; Champeaux, Jean-Philippe; Deville, Charlotte; Sence, Martine; Cafarelli, Pierre

2016-05-01

We have investigated collision-induced ionization and fragmentation by 100 keV protons of the radio sensitizing molecule cisplatin, which is used in cancer treatments. A large emission of HCl+ and NH2+ is observed, but surprisingly, no cationic fragments containing platinum are detected, in contrast to ionization-dissociation induced by electronic collision. Theoretical investigations show that the ionization processes take place on platinum and on chlorine atoms. We propose new ionization potentials for cisplatin. Dissociation limits corresponding to the measured fragmentation mass spectrum have been evaluated and the theoretical results show that the non-observed cationic fragments containing platinum are mostly associated with low dissociation energies. We have also investigated the reaction path for the hydrogen transfer from the NH3 group to the Cl atom, as well as the corresponding dissociation limits from this tautomeric form. Here again the cations containing platinum correspond to lower dissociation limits. Thus, the experimental results suggest that excited states, probably formed via inner-shell ionization of the platinum atom of the molecule, correlated to higher dissociation limits are favored.

Dissociated language functions: a matter of atypical language lateralization or cerebral plasticity?

PubMed

Acioly, Marcus Andre; Gharabaghi, Alireza; Zimmermann, Christoph; Erb, Michael; Heckl, Stefan; Tatagiba, Marcos

2014-01-01

The left hemisphere is generally considered to harbor language functions. Atypical cortical language lateralization is mainly demonstrated in left-handed and ambidextrous individuals, whereas dissociated language functions have been reported in association with brain injuries as a part of the reorganization process. We present a thoughtful discussion on the underlying mechanisms of dissociated language functions through an illustrative case of dissociated expressive language. A 31-year-old left-handed woman presented with a recurrent left frontal glioma. Preoperative language functional magnetic resonance imaging (fMRI) panel revealed right-sided dominance for two different language tasks (verbal fluency and visual naming), and the word chain task demonstrated maximal activation in the left hemisphere at the posterior margin of the tumor. The patient was operated on awake to assess language functions intraoperatively. Preoperative fMRI findings were confirmed revealing a task-specific dissociation of expressive language functions. Surgical resection was taken to the functional boundaries. Postoperatively, no language dysfunction occurred. Dissociated language functions are prone to occur in long-standing lesions. Different patterns of dissociation may be encountered due to interindividual particularities and cerebral plasticity. The presented patient is unique by demonstrating new insight into expressive language dissociation, emphasizing the role of a preoperative language fMRI panel and the capability of intraoperative language mapping for identifying special language networks. Georg Thieme Verlag KG Stuttgart · New York.

Interfacial disorder drives charge separation in molecular semiconductors

NASA Astrophysics Data System (ADS)

Willard, Adam

One of the fundamental microscopic processes in photocurrent generation is the dissociation of neutral photo-excitations (i.e., Frenkel excitons) into free charge carriers (i.e., electrons and holes). This process requires the physical separation of oppositely charged electrons and holes, which are held to together by an attractive electrostatic binding energy. In traditional inorganic-based photovoltaic (PV) materials, this binding energy is generally small and easily overcome, however, in organic-based PVs (OPVs) the exciton binding energy can significantly exceed thermal energies. The inability of bound charges to overcome this large binding energy has been implicated as a primary source of efficiency loss in OPVs. Here I present results from our recent efforts to explore the role of static molecular disorder in mediating this process. Using a simple lattice model of exciton dynamics we demonstrate that random spatial variations in the energetic landscape can mitigate the attractive Coulomb interaction between electrons and holes. We show that this effect manifests as a reduction in the free energy barrier for exciton dissociation that grows more pronounced with increasing disorder. By considering the competition between this thermodynamic effect and the disorder-induced slowing of dissociation kinetics we demonstrate that exciton dissociation yields are expected to depend non-monotonically on the degree of static disorder.

CH4 dissociation in the early stage of graphene growth on Fe-Cu(100) surface: Theoretical insights

NASA Astrophysics Data System (ADS)

Tian, Baoyang; Liu, Tianhui; Yang, YanYan; Li, Kai; Wu, Zhijian; Wang, Ying

2018-01-01

The mechanism of CH4 dissociation and carbon nucleation process on the Fe doped Cu(100) surface were investigated systematically by using the density functional theory (DFT) calculations and microkinetic model. The activity of the Cu(100) surface was improved by the doped Fe atom and the atomic Fe on the Fe-Cu(100) surface was the reaction center due to the synergistic effect. In the dissociation process of CH4, CH3 → CH2 + H was regarded as the rate-determining step. The results obtained from the microkinetic model showed that the coverage of CHx(x = 1-3) was gradually decreased with the temperature increasing and CH3 was always the major intermediate at the broad range of the temperature (from 1035 to 1080 °C) and the ratio of H2/CH4 (from 0 to 5). It is also found that the reaction rates were increased with the temperature increasing. However, the reaction rates were reduced (or increased) at the range of H2/CH4 = 0-0.2 (or H2/CH4 > 0.2). It is noted that controlling the H2 partial pressure was an effective method to regulate the major intermediates and reaction rates of CH4 dissociation and further influence the growing process of graphene.

Evaluating Computational Models in Cognitive Neuropsychology: The Case from the Consonant/Vowel Distinction

ERIC Educational Resources Information Center

Knobel, Mark; Caramazza, Alfonso

2007-01-01

Caramazza et al. [Caramazza, A., Chialant, D., Capasso, R., & Miceli, G. (2000). Separable processing of consonants and vowels. "Nature," 403(6768), 428-430.] report two patients who exhibit a double dissociation between consonants and vowels in speech production. The patterning of this double dissociation cannot be explained by appealing to…

Dissociative attachment of electrons to N2O

NASA Technical Reports Server (NTRS)

Krishnakumar, E.; Srivastava, S. K.

1990-01-01

Cross sections for the production of O(-) from N2O by the process of dissociative electron attachment have been measured for electron-impact energies ranging from 0 to 50 eV. Three new O(-) peaks are observed. The present data above 5-eV electron-impact energy differ considerably from the previous measurements.

Functional Dissociation between Perception and Action Is Evident Early in Life

ERIC Educational Resources Information Center

Hadad, Bat-Sheva; Avidan, Galia; Ganel, Tzvi

2012-01-01

The functional distinction between vision for perception and vision for action is well documented in the mature visual system. Ganel and colleagues recently provided direct evidence for this dissociation, showing that while visual processing for perception follows Weber's fundamental law of psychophysics, action violates this law. We tracked the…

Contributions of 3'-overhang to the dissociation of small interfering RNAs from the PAZ domain: molecular dynamics simulation study.

PubMed

Lee, Hui Sun; Lee, Soo Nam; Joo, Chul Hyun; Lee, Heuiran; Lee, Han Saem; Yoon, Seung Yong; Kim, Yoo Kyum; Choe, Han

2007-03-01

RNA interference (RNAi) is a 'knock-down' reaction to reduce expression of a specific gene through highly regulated, enzyme-mediated processes. Small interfering RNAs (siRNAs) are RNA molecules that play an effector role in RNAi and can bind the PAZ domains present in Dicer and RISC. We investigated the interaction between the PAZ domain and the siRNA-like duplexes through dissociation molecular dynamics (DMD) simulations. Specifically, we focused on the response of the PAZ domain to various 3'-overhang structures of the siRNA-like duplexes. We found that the siRNA-like duplex with the 3' UU-overhang made relatively more stable complex with the PAZ domain compared to those with 3' CC-, AA-, and GG-overhangs. The siRNA-like duplex with UU-overhang was easily dissociated from the PAZ domain once the structural stability of the complex is impaired. Interestingly, the 3' UU-overhang spent the least time at the periphery region of the binding pocket during the dissociation process, which can be mainly attributable to UU-overhang's smallest number of hydrogen bonds.

Process for analyzing CO[sub 2] in air and in water

DOEpatents

Atwater, J.E.; Akse, J.R.; DeHart, J.

1999-06-08

The process of this invention comprises providing a membrane for separating CO[sub 2] into a first CO[sub 2] sample phase and a second CO[sub 2] analyte phase. CO[sub 2] is then transported through the membrane thereby separating the CO[sub 2] with the membrane into a first CO[sub 2] sample phase and a second CO[sub 2] analyte liquid phase including an ionized, conductive, dissociated CO[sub 2] species. Next, the concentration of the ionized, conductive, dissociated CO[sub 2] species in the second CO[sub 2] analyte liquid phase is chemically amplified using a water-soluble chemical reagent which reversibly reacts with undissociated CO[sub 2] to produce conductivity changes therein corresponding to fluctuations in the partial pressure of CO[sub 2] in the first CO[sub 2] sample phase. Finally, the chemically amplified, ionized, conductive, dissociated CO[sub 2] species is introduced to a conductivity measuring instrument. Conductivity changes in the chemically amplified, ionized, conductive, dissociated CO[sub 2] species are detected using the conductivity measuring instrument. 43 figs.

Process for analyzing CO.sub.2 in air and in water

DOEpatents

Atwater, James E.; Akse, James R.; DeHart, Jeffrey

1999-01-01

The process of this invention comprises providing a membrane for separating CO.sub.2 into a first CO.sub.2 sample phase and a second CO.sub.2 analyte phase. CO.sub.2 is then transported through the membrane thereby separating the CO.sub.2 with the membrane into a first CO.sub.2 sample phase and a second CO.sub.2 analyte liquid phase including an ionized, conductive, dissociated CO.sub.2 species. Next, the concentration of the ionized, conductive, dissociated CO.sub.2 species in the second CO.sub.2 analyte liquid phase is chemically amplified using a water-soluble chemical reagent which reversibly reacts with undissociated CO.sub.2 to produce conductivity changes therein corresponding to fluctuations in the partial pressure of CO.sub.2 in the first CO.sub.2 sample phase. Finally, the chemically amplified, ionized, conductive, dissociated CO.sub.2 species is introduced to a conductivity measuring instrument. Conductivity changes in the chemically amplified, ionized, conductive, dissociated CO.sub.2 species are detected using the conductivity measuring instrument.

Dissociation of dicyclohexyl phthalate molecule induced by low-energy electron impact

NASA Astrophysics Data System (ADS)

Lacko, Michal; Papp, Peter; Matejčík, Štefan

2018-06-01

Experimental investigation of electron ionization (EI) of and electron attachment (EA) onto dicyclohexyl phthalate (DCHP) was carried out using a crossed electron and molecular beam technique. Formation of positive and negative ions by EI and EA with the corresponding dissociation processes was studied and discussed. Due to a low ion yield of the parent positive ion, we were not able to estimate the ionization energy of DCHP. However, we estimated the appearance energies for the protonated phthalate anhydride (m/z 149) to be 10.5 eV and other significant ionic fragments of m/z 249 [DCHP—(R—2H)]+, m/z 167 [DCHP—(2R—3H)]+, and m/z 83 [C6H11]+. The reaction mechanisms of the dissociative ionization process were discussed. In the case of negative ions, we estimated the relative cross sections for a transient negative ion (TNI) and for several detected ions. At low electron energies (close to 0 eV), the TNI of DCHP molecules was the dominant ion, with products of dissociative EA dominating in broad resonances at 7.5 and 8.5 eV.

Process for analyzing CO{sub 2} in seawater

DOEpatents

Atwater, J.E.; Akse, J.R.; DeHart, J.

1997-07-01

The process of this invention comprises providing a membrane for separating CO{sub 2} into a first CO{sub 2} sample phase and a second CO{sub 2} analyte phase. CO{sub 2} is then transported through the membrane thereby separating the CO{sub 2} with the membrane into a first CO{sub 2} sample phase and a second CO{sub 2} analyte liquid phase including an ionized, conductive, dissociated CO{sub 2} species. Next, the concentration of the ionized, conductive, dissociated CO{sub 2} species in the second CO{sub 2} analyte liquid phase is chemically amplified using a water-soluble chemical reagent which reversibly reacts with undissociated CO{sub 2} to produce conductivity changes therein corresponding to fluctuations in the partial pressure of CO{sub 2} in the first CO{sub 2} sample phase. Finally, the chemically amplified, ionized, conductive, dissociated CO{sub 2} species is introduced to a conductivity measuring instrument. Conductivity changes in the chemically amplified, ionized, conductive, dissociated CO{sub 2} species are detected using the conductivity measuring instrument. 43 figs.

Measurement of Neutrino-Induced Coherent Pion Production and the Diffractive Background in MINERvA

NASA Astrophysics Data System (ADS)

Gomez, Alicia; Minerva Collaboration

2015-04-01

Neutrino-induced coherent charged pion production is a unique neutrino-nucleus scattering process in which a muon and pion are produced while the nucleus is left in its ground state. The MINERvA experiment has made a model-independent differential cross section measurement of this process on carbon by selecting events with a muon and a pion, no evidence of nuclear break-up, and small momentum transfer to the nucleus | t | . A similar process which is a background to the measurement on carbon is diffractive pion production off the free protons in MINERvA's scintillator. This process is not modeled in the neutrino event generator GENIE. At low | t | these events have a similar final state to the aforementioned process. A study to quantify this diffractive event contribution to the background is done by emulating these diffractive events by reweighting all other GENIE-generated background events to the predicted | t | distribution of diffractive events, and then scaling to the diffractive cross section.

Dissociating interference-control processes between memory and response.

PubMed

Bissett, Patrick G; Nee, Derek Evan; Jonides, John

2009-09-01

The ability to mitigate interference is of central importance to cognition. Previous research has provided conflicting accounts about whether operations that resolve interference are singular in character or form a family of functions. Here, the authors examined the relationship between interference-resolution processes acting on working memory representations versus responses. The authors combined multiple forms of interference into a single paradigm by merging a directed-forgetting task, which induces proactive interference, with a stop-signal task, which taps response inhibition processes. The results demonstrated that proactive interference and response inhibition produced distinct behavioral signatures that did not interact. By contrast, combining two different measures of response inhibition by merging a go/no-go task variant and a stop signal produced overadditive behavioral interference, demonstrating that different forms of response inhibition tap the same processes. However, not all forms of response conflict interacted, suggesting that inhibition-related functions acting on response selection are dissociable from those acting on response inhibition. These results suggest that inhibition-related functions for memory and responses are dissociable. (c) 2009 APA, all rights reserved.

The parietal cortex in sensemaking: the dissociation of multiple types of spatial information.

PubMed

Sun, Yanlong; Wang, Hongbin

2013-01-01

According to the data-frame theory, sensemaking is a macrocognitive process in which people try to make sense of or explain their observations by processing a number of explanatory structures called frames until the observations and frames become congruent. During the sensemaking process, the parietal cortex has been implicated in various cognitive tasks for the functions related to spatial and temporal information processing, mathematical thinking, and spatial attention. In particular, the parietal cortex plays important roles by extracting multiple representations of magnitudes at the early stages of perceptual analysis. By a series of neural network simulations, we demonstrate that the dissociation of different types of spatial information can start early with a rather similar structure (i.e., sensitivity on a common metric), but accurate representations require specific goal-directed top-down controls due to the interference in selective attention. Our results suggest that the roles of the parietal cortex rely on the hierarchical organization of multiple spatial representations and their interactions. The dissociation and interference between different types of spatial information are essentially the result of the competition at different levels of abstraction.

The Parietal Cortex in Sensemaking: The Dissociation of Multiple Types of Spatial Information

PubMed Central

Sun, Yanlong; Wang, Hongbin

2013-01-01

According to the data-frame theory, sensemaking is a macrocognitive process in which people try to make sense of or explain their observations by processing a number of explanatory structures called frames until the observations and frames become congruent. During the sensemaking process, the parietal cortex has been implicated in various cognitive tasks for the functions related to spatial and temporal information processing, mathematical thinking, and spatial attention. In particular, the parietal cortex plays important roles by extracting multiple representations of magnitudes at the early stages of perceptual analysis. By a series of neural network simulations, we demonstrate that the dissociation of different types of spatial information can start early with a rather similar structure (i.e., sensitivity on a common metric), but accurate representations require specific goal-directed top-down controls due to the interference in selective attention. Our results suggest that the roles of the parietal cortex rely on the hierarchical organization of multiple spatial representations and their interactions. The dissociation and interference between different types of spatial information are essentially the result of the competition at different levels of abstraction. PMID:23710165

Synthesis, crystal structure, DFT studies, acid dissociation constant, and antimicrobial activity of methyl 2-(4-chlorophenyl)-7a-((4-chlorophenyl)carbamothioyl)-1-oxo-5,5-diphenyl-3-thioxo-hexahydro-1H-pyrrolo[1,2-e]imidazole-6-carboxylate

NASA Astrophysics Data System (ADS)

Nural, Yahya; Gemili, Muge; Seferoglu, Nurgul; Sahin, Ertan; Ulger, Mahmut; Sari, Hayati

2018-05-01

A novel bicyclic thiohydantoin fused to pyrrolidine compound, methyl 2-(4-chlorophenyl)-7a-((4-chlorophenyl)carbamothioyl)-1-oxo-5,5-diphenyl-3-thioxo-hexahydro-1H-pyrrolo[1,2-e]imidazole-6-carboxylate, was synthesized by the cyclization reaction of dimethyl 5,5-diphenylpyrrolidine-2,4-dicarboxylate and 4-chlorophenyl isothiocyanate in the presence of 4-(dimethylamino)pyridine to form methyl 2-(4-chlorophenyl)-1-oxo-5,5-diphenyl-3-thioxo-hexahydro-1H-pyrrolo[1,2-e]imidazole-6-carboxylate with concomitant addition reaction of the 4-chlorophenyl isothiocyanate in 79% yield. The structural characterization was performed by NMR, FT-IR, MS and HRMS techniques, and the stereochemistry of the compound was determined by single crystal X-ray diffraction study. In addition, the molecular structure and 1H and 13C NMR chemical shifts of the compound were obtained with the density functional theory and Hartree-Fock calculations. Acid dissociation constants of the compound were determined using potentiometric titration method in 25% (v/v) dimethyl sulfoxide-water hydroorganic solvent at 25 ± 0.1 °C, at an ionic background of 0.1 mol/L of NaCl using the HYPERQUAD computer program. Four acid dissociation constants were obtained for the compound, and we suggest that these acid dissociation constants are related to the NH, for two groups of enthiols and enol groups. Antimicrobial activity study was performed against S. aureus, B. subtilis, A. hydrophila, E. coli and A. baumannii as bacterial standard strains, and against M. tuberculosis H37Rv as mycobacterial strain. The compound exhibited antibacterial activity in the range of 31.25-62.5 μg/mL, and antimycobacterial activity with a MIC value of 40 μg/mL against the indicated strains.

Hemispheric Asymmetry of Visual Scene Processing in the Human Brain: Evidence from Repetition Priming and Intrinsic Activity

PubMed Central

Kahn, Itamar; Wig, Gagan S.; Schacter, Daniel L.

2012-01-01

Asymmetrical specialization of cognitive processes across the cerebral hemispheres is a hallmark of healthy brain development and an important evolutionary trait underlying higher cognition in humans. While previous research, including studies of priming, divided visual field presentation, and split-brain patients, demonstrates a general pattern of right/left asymmetry of form-specific versus form-abstract visual processing, little is known about brain organization underlying this dissociation. Here, using repetition priming of complex visual scenes and high-resolution functional magnetic resonance imaging (MRI), we demonstrate asymmetrical form specificity of visual processing between the right and left hemispheres within a region known to be critical for processing of visual spatial scenes (parahippocampal place area [PPA]). Next, we use resting-state functional connectivity MRI analyses to demonstrate that this functional asymmetry is associated with differential intrinsic activity correlations of the right versus left PPA with regions critically involved in perceptual versus conceptual processing, respectively. Our results demonstrate that the PPA comprises lateralized subregions across the cerebral hemispheres that are engaged in functionally dissociable yet complementary components of visual scene analysis. Furthermore, this functional asymmetry is associated with differential intrinsic functional connectivity of the PPA with distinct brain areas known to mediate dissociable cognitive processes. PMID:21968568

Hemispheric asymmetry of visual scene processing in the human brain: evidence from repetition priming and intrinsic activity.

PubMed

Stevens, W Dale; Kahn, Itamar; Wig, Gagan S; Schacter, Daniel L

2012-08-01

Asymmetrical specialization of cognitive processes across the cerebral hemispheres is a hallmark of healthy brain development and an important evolutionary trait underlying higher cognition in humans. While previous research, including studies of priming, divided visual field presentation, and split-brain patients, demonstrates a general pattern of right/left asymmetry of form-specific versus form-abstract visual processing, little is known about brain organization underlying this dissociation. Here, using repetition priming of complex visual scenes and high-resolution functional magnetic resonance imaging (MRI), we demonstrate asymmetrical form specificity of visual processing between the right and left hemispheres within a region known to be critical for processing of visual spatial scenes (parahippocampal place area [PPA]). Next, we use resting-state functional connectivity MRI analyses to demonstrate that this functional asymmetry is associated with differential intrinsic activity correlations of the right versus left PPA with regions critically involved in perceptual versus conceptual processing, respectively. Our results demonstrate that the PPA comprises lateralized subregions across the cerebral hemispheres that are engaged in functionally dissociable yet complementary components of visual scene analysis. Furthermore, this functional asymmetry is associated with differential intrinsic functional connectivity of the PPA with distinct brain areas known to mediate dissociable cognitive processes.

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

PubMed

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

2017-01-01

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

Mechanism of Phosphine Dissociation on the Si(001) Surface

NASA Astrophysics Data System (ADS)

Warschkow, Oliver; Schofield, Steven R.; Smith, Phil V.

2005-03-01

The continued down-scaling of electronic devices to the atomic scale increasingly requires an atomic-level understanding of the elementary processes of semiconductor doping. We present a combined experimental and theoretical investigation into the dissociation mechanism of phosphine (PH3) on the Si(001) surface. As reported by us elsewhere in this conference, a number of prominent intermediate species of PH3 dissociation observed in STM experiments have been structurally characterized as PH2+H, PH+2H and P+3H species respectively. In this poster we present detailed quantum chemical calculations of these and other short-lived intermediates as well as the transition (kinetic) barriers between them. This leads us to formulate a step-by-step mechanism for the complete dissociation of PH3 on the Si(001) surface.

Simplified model to describe the dissociative recombination of linear polyatomic ions of astrophysical interest

NASA Astrophysics Data System (ADS)

Douguet, N.; Fonseca dos Santos, S.; Kokoouline, V.; Orel, A. E.

2015-01-01

We present results of a theoretical study on dissociative recombination of the HCNH+, HCO+ and N2H+ linear polyatomic ions at low energies using a simple theoretical model. In the present study, the indirect mechanism for recombination proceeds through the capture of the incoming electron in excited vibrational Rydberg states attached to the degenerate transverse modes of the linear ions. The strength of the non-adiabatic coupling responsible for dissociative recombination is determined directly from the near-threshold scattering matrix obtained numerically using the complex Kohn variational method. The final cross sections for the process are compared with available experimental data. It is demonstrated that at low collision energies, the major contribution to the dissociative recombination cross section is due to the indirect mechanism.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Országh, Juraj; Danko, Marián; Čechvala, Peter

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

Domain-specific control mechanisms for emotional and nonemotional conflict processing.

PubMed

Soutschek, Alexander; Schubert, Torsten

2013-02-01

Recent neuroimaging studies suggest that the human brain activates dissociable cognitive control networks in response to conflicts arising within the cognitive and the affective domain. The present study tested the hypothesis that nonemotional and emotional conflict regulation can also be dissociated on a functional level. For that purpose, we examined the effects of a working memory and an emotional Go/Nogo task on cognitive control in an emotional and a nonemotional variant of the Stroop paradigm. The data confirmed the hypothesized dissociation: Working memory efforts selectively suppressed conflict regulation in the nonemotional Stroop task, while the demands of an emotional Go/Nogo task impaired only conflict regulation in the emotional Stroop task. We conclude that these findings support a modular architecture of cognitive control with domain-specific conflict regulation processes. Copyright © 2012 Elsevier B.V. All rights reserved.

Processes of conscious and unconscious memory: evidence from current research on dissociation of memories within a test.

PubMed

Cheng, Chao-Ming; Huang, Chin-Lan

2011-01-01

The processes of conscious memory (CM) and unconscious memory (UM) are explored, based on the results of the current and previous studies in which the 2 forms of memory within a test were separated by either the process dissociation or metacognition-based dissociation procedure. The results assessing influences of shallow and deep processing, association, and self-generation on CM in explicit and implicit tests are taken as evidence that CM in a test is driven not only conceptually but also by the driving nature of the test, and CM benefits from an encoding condition to the extent that information processing for CM recapitulates that engaged in the encoding condition.Those influences on UM in explicit and implicit tests are taken to support the view that UM in a test is driven by the nature of the test itself, and UM benefits from an encoding condition to the extent that the cognitive environments at test and at study match to activate the same type of information (e.g., visual, lexical, or semantic) about memory items or the same content of a preexisting association or categorical structure.

Aggregation-induced chemical reactions: acid dissociation in growing water clusters.

PubMed

Forbert, Harald; Masia, Marco; Kaczmarek-Kedziera, Anna; Nair, Nisanth N; Marx, Dominik

2011-03-23

Understanding chemical reactivity at ultracold conditions, thus enabling molecular syntheses via interstellar and atmospheric processes, is a key issue in cryochemistry. In particular, acid dissociation and proton transfer reactions are ubiquitous in aqueous microsolvation environments. Here, the full dissociation of a HCl molecule upon stepwise solvation by a small number of water molecules at low temperatures, as relevant to helium nanodroplet isolation (HENDI) spectroscopy, is analyzed in mechanistic detail. It is found that upon successive aggregation of HCl with H(2)O molecules, a series of cyclic heteromolecular structures, up to and including HCl(H(2)O)(3), are initially obtained before a precursor state for dissociation, HCl(H(2)O)(3)···H(2)O, is observed upon addition of a fourth water molecule. The latter partially aggregated structure can be viewed as an "activated species", which readily leads to dissociation of HCl and to the formation of a solvent-shared ion pair, H(3)O(+)(H(2)O)(3)Cl(-). Overall, the process is mostly downhill in potential energy, and, in addition, small remaining barriers are overcome by using kinetic energy released as a result of forming hydrogen bonds due to aggregation. The associated barrier is not ruled by thermal equilibrium but is generated by athermal non-equilibrium dynamics. These "aggregation-induced chemical reactions" are expected to be of broad relevance to chemistry at ultralow temperature much beyond HENDI spectroscopy.

Validation of the Italian version of the dissociative experience scale for adolescents and young adults.

PubMed

De Pasquale, Concetta; Sciacca, Federica; Hichy, Zira

2016-01-01

The Dissociative Experience Scale for adolescent (A-DES), a 30-item, multidimensional, self-administered questionnaire, was validated using a large sample of American young people sample. We reported the linguistic validation process and the metric validity of the Italian version of A-DES in the Italy. A set of questionnaires was provided to a total of 633 participants from March 2015 to April 2016. The participants consisted of 282 boys and 351 girls, and their average age was between 18 and 24 years old. The translation process consisted of two consecutive steps: forward-backward translation and acceptability testing. The psychometric testing was applied to Italian students who were recruited from the Italian Public Schools and Universities in Sicily. Informed consent was obtained from all participants at the research. All individuals completed the A-DES. Reliability and validity were tested. The translated version was validated on a total of 633 Italian students. The reliability of A-DES total is .926. It is composed by 4 subscales: Dissociative amnesia, Absorption and imaginative involvement, Depersonalization and derealization, and Passive influence. The reliability of each subscale is: .756 for dissociative amnesia, .659 for absorption and imaginative involvement, .850 for depersonalization and derealization, and .743 for passive influence. The Italian version of the A-DES constitutes a useful instrument to measure dissociative experience in adolescents and young adults in Italy.

Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS3 experiments.

PubMed

Boukerche, Toufik Taalibi; Alves, Sandra; Le Faouder, Pauline; Warnet, Anna; Bertrand-Michel, Justine; Bouchekara, Mohamed; Belbachir, Mohammed; Tabet, Jean-Claude

2016-12-01

Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA (*D) and LAA (*E) ). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA (*D/*E) +H)-C 2 H 5 OH] + product ions dissociate via distinct pathways in sequential MS 3 experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA (*D), whereas LAA (*E) leads to the [*E+H-H 2 O] + anhydride. The former releases ammonia to provide acylium, which gives the C n H (2n-1) and C n H (2n-3) carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MS n experiments.

Body knowledge in brain-damaged children: a double-dissociation in self and other's body processing.

PubMed

Frassinetti, Francesca; Fiori, Simona; D'Angelo, Valentina; Magnani, Barbara; Guzzetta, Andrea; Brizzolara, Daniela; Cioni, Giovanni

2012-01-01

Bodies are important element for self-recognition. In this respect, in adults it has been recently shown a self vs other advantage when small parts of the subjects' body are visible. This advantage is lost following a right brain lesion underlying a role of the right hemisphere in self body-parts processing. In order to investigate the bodily-self processing in children and the development of its neuronal bases, 57 typically developing healthy subjects and 17 subjects with unilateral brain damage (5 right and 12 left sided), aged 4-17 years, were submitted to a matching-to-sample task. In this task, three stimuli vertically aligned were simultaneously presented at the centre of the computer screen. Subjects were required which of two stimuli (the upper or the lower one) matched the central target stimulus, half stimuli representing self and half stimuli representing other people's body-parts and face-parts. The results showed that corporeal self recognition is present since at least 4 years of age and that self and others' body parts processing are different and sustained by separate cerebral substrates. Indeed, a double dissociation was found: right brain damaged patients were impaired in self but not in other people's body parts, showing a self-disadvantage, whereas left brain damaged patients were impaired in others' but not in self body parts processing. Finally, since the double dissociation self/other was found for body-parts but not for face parts, the corporal self seems to be dissociated for body and face-parts. This opens the possibility of independent and lateralized functional modules for the processing of self and other body parts during development. Copyright © 2011 Elsevier Ltd. All rights reserved.

RECOGNIZING AND IDENTIFYING PEOPLE: A neuropsychological review

PubMed Central

Barton, Jason J S; Corrow, Sherryse L

2016-01-01

Recognizing people is a classic example of a cognitive function that involves multiple processing stages and parallel routes of information. Neuropsychological data have provided important evidence for models of this process, particularly from case reports; however, the quality and extent of the data varies widely between studies. In this review we first discuss the requirements and logical basis of the types of neuropsychological evidence to support conclusions about the modules in this process. We then survey the adequacy of the current body of reports to address two key issues. First is the question of which cognitive operation generates a sense of familiarity: the current debate revolves around whether familiarity arises in modality-specific recognition units or later amodal processes. Key evidence on this point comes from the search for dissociations between familiarity for faces, voices and names. The second question is whether lesions can differentially affect the abilities to link diverse sources of person information (e.g. face, voice, name, biographic data). Dissociations of these linkages may favour a distributed-only model of the organization of semantic knowledge, whereas a ‘person-hub’ model would predict uniform impairments of all linkages. While we conclude that there is reasonable evidence for dissociations in name, voice and face familiarity in regards to the first question, the evidence for or against dissociated linkages between information stores in regards to the second is tenuous at best. We identify deficiencies in the current literature that should motivate and inform the design of future studies. PMID:26773237

Atmospheric opacity in the Schumann-Runge bands and the aeronomic dissociation of water vapor

NASA Technical Reports Server (NTRS)

Frederick, J. E.; Hudson, R. D.

1980-01-01

Knowledge of the aeronomic production of odd hydrogen in the dissociation of water vapor is limited by uncertainties in the penetration of solar irradiance in the Schumann-Runge bands of O2 and by incomplete information concerning the products of photolysis at Lyman alpha. Consideration of all error sources involved in computing the H2O dissociation rate in the wavelength region 175-200 nm leads to an estimated uncertainty of plus or minus 35% at an altitude of 90 km for an overhead sun. The uncertainty increases with decreasing altitude such that the true dissociation rate at 60 km for an overhead sun lies between 0.45 and 1.55 times the results computed using the best input parameters currently available. Calculations of the H2O dissociation rate by Lyman alpha should include the variation in O2 opacity across the solar line width. Neglect of this can lead to errors as large as 50% at altitudes where the process is the major source of odd hydrogen.

Knowledge-based probabilistic representations of branching ratios in chemical networks: The case of dissociative recombinations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plessis, Sylvain; Carrasco, Nathalie; Pernot, Pascal

Experimental data about branching ratios for the products of dissociative recombination of polyatomic ions are presently the unique information source available to modelers of natural or laboratory chemical plasmas. Yet, because of limitations in the measurement techniques, data for many ions are incomplete. In particular, the repartition of hydrogen atoms among the fragments of hydrocarbons ions is often not available. A consequence is that proper implementation of dissociative recombination processes in chemical models is difficult, and many models ignore invaluable data. We propose a novel probabilistic approach based on Dirichlet-type distributions, enabling modelers to fully account for the available information.more » As an application, we consider the production rate of radicals through dissociative recombination in an ionospheric chemistry model of Titan, the largest moon of Saturn. We show how the complete scheme of dissociative recombination products derived with our method dramatically affects these rates in comparison with the simplistic H-loss mechanism implemented by default in all recent models.« less

Knowledge-based probabilistic representations of branching ratios in chemical networks: the case of dissociative recombinations.

PubMed

Plessis, Sylvain; Carrasco, Nathalie; Pernot, Pascal

2010-10-07

Experimental data about branching ratios for the products of dissociative recombination of polyatomic ions are presently the unique information source available to modelers of natural or laboratory chemical plasmas. Yet, because of limitations in the measurement techniques, data for many ions are incomplete. In particular, the repartition of hydrogen atoms among the fragments of hydrocarbons ions is often not available. A consequence is that proper implementation of dissociative recombination processes in chemical models is difficult, and many models ignore invaluable data. We propose a novel probabilistic approach based on Dirichlet-type distributions, enabling modelers to fully account for the available information. As an application, we consider the production rate of radicals through dissociative recombination in an ionospheric chemistry model of Titan, the largest moon of Saturn. We show how the complete scheme of dissociative recombination products derived with our method dramatically affects these rates in comparison with the simplistic H-loss mechanism implemented by default in all recent models.

Organic photovoltaics: elucidating the ultra-fast exciton dissociation mechanism in disordered materials.

PubMed

Heitzer, Henry M; Savoie, Brett M; Marks, Tobin J; Ratner, Mark A

2014-07-14

Organic photovoltaics (OPVs) offer the opportunity for cheap, lightweight and mass-producible devices. However, an incomplete understanding of the charge generation process, in particular the timescale of dynamics and role of exciton diffusion, has slowed further progress in the field. We report a new Kinetic Monte Carlo model for the exciton dissociation mechanism in OPVs that addresses the origin of ultra-fast (<1 ps) dissociation by incorporating exciton delocalization. The model reproduces experimental results, such as the diminished rapid dissociation with increasing domain size, and also lends insight into the interplay between mixed domains, domain geometry, and exciton delocalization. Additionally, the model addresses the recent dispute on the origin of ultra-fast exciton dissociation by comparing the effects of exciton delocalization and impure domains on the photo-dynamics.This model provides insight into exciton dynamics that can advance our understanding of OPV structure-function relationships. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dissociation of Subtraction and Multiplication in the Right Parietal Cortex: Evidence from Intraoperative Cortical Electrostimulation

ERIC Educational Resources Information Center

Yu, Xiaodan; Chen, Chuansheng; Pu, Song; Wu, Chenxing; Li, Yongnian; Jiang, Tao; Zhou, Xinlin

2011-01-01

Previous research has consistently shown that the left parietal cortex is critical for numerical processing, but the role of the right parietal lobe has been much less clear. This study used the intraoperative cortical electrical stimulation approach to investigate neural dissociation in the right parietal cortex for subtraction and…

A Validation Study of the Adolescent Dissociative Experiences Scale

ERIC Educational Resources Information Center

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

2004-01-01

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

Affective Association: An Effective Intervention in Countering Fragmentation and Dissociation

ERIC Educational Resources Information Center

Hart, Carolyn

2008-01-01

This paper is concerned with the processes, both psychoanalytic and neuroscientific, involved in the undoing of dissociation in a 3-year-old, who was seen weekly over a nine month period. A neuroscientific and psychoanalytic developmental framework is used to follow a sequence of phenomena that emerged over the duration of relatively brief once…

Data processing software suite SITENNO for coherent X-ray diffraction imaging using the X-ray free-electron laser SACLA.

PubMed

Sekiguchi, Yuki; Oroguchi, Tomotaka; Takayama, Yuki; Nakasako, Masayoshi

2014-05-01

Coherent X-ray diffraction imaging is a promising technique for visualizing the structures of non-crystalline particles with dimensions of micrometers to sub-micrometers. Recently, X-ray free-electron laser sources have enabled efficient experiments in the `diffraction before destruction' scheme. Diffraction experiments have been conducted at SPring-8 Angstrom Compact free-electron LAser (SACLA) using the custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors. In the experiments, ten thousands of single-shot diffraction patterns can be collected within several hours. Then, diffraction patterns with significant levels of intensity suitable for structural analysis must be found, direct-beam positions in diffraction patterns determined, diffraction patterns from the two CCD detectors merged, and phase-retrieval calculations for structural analyses performed. A software suite named SITENNO has been developed to semi-automatically apply the four-step processing to a huge number of diffraction data. Here, details of the algorithm used in the suite are described and the performance for approximately 9000 diffraction patterns collected from cuboid-shaped copper oxide particles reported. Using the SITENNO suite, it is possible to conduct experiments with data processing immediately after the data collection, and to characterize the size distribution and internal structures of the non-crystalline particles.

Data processing software suite SITENNO for coherent X-ray diffraction imaging using the X-ray free-electron laser SACLA

PubMed Central

Sekiguchi, Yuki; Oroguchi, Tomotaka; Takayama, Yuki; Nakasako, Masayoshi

2014-01-01

Coherent X-ray diffraction imaging is a promising technique for visualizing the structures of non-crystalline particles with dimensions of micrometers to sub-micrometers. Recently, X-ray free-electron laser sources have enabled efficient experiments in the ‘diffraction before destruction’ scheme. Diffraction experiments have been conducted at SPring-8 Angstrom Compact free-electron LAser (SACLA) using the custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors. In the experiments, ten thousands of single-shot diffraction patterns can be collected within several hours. Then, diffraction patterns with significant levels of intensity suitable for structural analysis must be found, direct-beam positions in diffraction patterns determined, diffraction patterns from the two CCD detectors merged, and phase-retrieval calculations for structural analyses performed. A software suite named SITENNO has been developed to semi-automatically apply the four-step processing to a huge number of diffraction data. Here, details of the algorithm used in the suite are described and the performance for approximately 9000 diffraction patterns collected from cuboid-shaped copper oxide particles reported. Using the SITENNO suite, it is possible to conduct experiments with data processing immediately after the data collection, and to characterize the size distribution and internal structures of the non-crystalline particles. PMID:24763651

Analyzing angular distributions for two-step dissociation mechanisms in velocity map imaging.

PubMed

Straus, Daniel B; Butler, Lynne M; Alligood, Bridget W; Butler, Laurie J

2013-08-15

Increasingly, velocity map imaging is becoming the method of choice to study photoinduced molecular dissociation processes. This paper introduces an algorithm to analyze the measured net speed, P(vnet), and angular, β(vnet), distributions of the products from a two-step dissociation mechanism, where the first step but not the second is induced by absorption of linearly polarized laser light. Typically, this might be the photodissociation of a C-X bond (X = halogen or other atom) to produce an atom and a momentum-matched radical that has enough internal energy to subsequently dissociate (without the absorption of an additional photon). It is this second step, the dissociation of the unstable radicals, that one wishes to study, but the measured net velocity of the final products is the vector sum of the velocity imparted to the radical in the primary photodissociation (which is determined by taking data on the momentum-matched atomic cophotofragment) and the additional velocity vector imparted in the subsequent dissociation of the unstable radical. The algorithm allows one to determine, from the forward-convolution fitting of the net velocity distribution, the distribution of velocity vectors imparted in the second step of the mechanism. One can thus deduce the secondary velocity distribution, characterized by a speed distribution P(v1,2°) and an angular distribution I(θ2°), where θ2° is the angle between the dissociating radical's velocity vector and the additional velocity vector imparted to the product detected from the subsequent dissociation of the radical.

Vibrational studies of flexible solid polymer electrolyte based on PCL-EC incorporated with proton conducting NH4SCN

NASA Astrophysics Data System (ADS)

Woo, H. J.; Arof, A. K.

2016-05-01

A flexible solid polymer electrolyte (SPE) system based on poly(ε-caprolactone) (PCL), a FDA approved non-toxic and biodegradable material in the effort to lower environmental impact was prepared. Ammonium thiocyanate (NH4SCN) and ethylene carbonate (EC) were incorporated as the source of charge carriers and plasticizing agent, respectively. When 50 wt.% of ethylene carbonate (EC) was added to PCL-NH4SCN system, the conductivity increased by two orders from of 3.94 × 10- 7 Scm- 1 to 3.82 × 10- 5 Scm- 1. Molecular vibrational analysis via infrared spectroscopy had been carried out to study the interaction between EC, PCL and NH4SCN. The relative percentage of free ions, ion pairs and ion aggregates was calculated quantitatively by deconvoluting the SCN- stretching mode (2030-2090 cm- 1). This study provides fundamental insight on how EC influences the free ion dissociation rate and ion mobility. The findings are also in good agreement to conductivity, differential scanning calorimetry and X-ray diffraction results. High dielectric constant value (89.8) of EC had made it an effective ion dissociation agent to dissociate both ion pairs and ion aggregates, thus contributing to higher number density of free ions. The incorporation of EC had made the polymer chains more flexible in expanding amorphous domain. This will facilitate the coupling synergy between ionic motion and polymer segmental motion. Possible new pathway through EC-NH4+ complex sites for ions to migrate with shorter distance has been anticipated. This implies an easier ion migration route from one complex site to another.

Phase diagram and high-pressure boundary of hydrate formation in the ethane-water system.

PubMed

Kurnosov, Alexander V; Ogienko, Andrey G; Goryainov, Sergei V; Larionov, Eduard G; Manakov, Andrey Y; Lihacheva, Anna Y; Aladko, Eugeny Y; Zhurko, Fridrikh V; Voronin, Vladimir I; Berger, Ivan F; Ancharov, Aleksei I

2006-11-02

Dissociation temperatures of gas hydrate formed in the ethane-water system were studied at pressures up to 1500 MPa. In situ neutron diffraction analysis and X-ray diffraction analysis in a diamond anvil cell showed that the gas hydrate formed in the ethane-water system at 340, 700, and 1840 MPa and room temperature belongs to the cubic structure I (CS-I). Raman spectra of C-C vibrations of ethane molecules in the hydrate phase, as well as the spectra of solid and liquid ethane under high-pressure conditions were studied at pressures up to 6900 MPa. Within 170-3600 MPa Raman shift of the C-C vibration mode of ethane in the hydrate phase did not show any discontinuities, which could be evidence of possible phase transformations. The upper pressure boundary of high-pressure hydrate existence was discovered at the pressure of 3600 MPa. This boundary corresponds to decomposition of the hydrate to solid ethane and ice VII. The type of phase diagram of ethane-water system was proposed in the pressure range of hydrate formation (0-3600 MPa).

Effects of a TiC substrate on the catalytic activity of Pt for NO reduction.

PubMed

Chu, Xingli; Fu, Zhaoming; Li, Shasha; Zhang, Xilin; Yang, Zongxian

2016-05-11

Density functional theory calculations are used to elucidate the catalytic properties of a Pt monolayer supported on a TiC(001) substrate (Pt/TiC) toward NO reduction. It is found that the compound system of Pt/TiC has a good stability due to the strong Pt-TiC interaction. The diverse dissociation paths (namely the direct dissociation mechanism and the dimeric mechanism) are investigated. The transition state searching calculations suggest that NO has strong diffusion ability and small activation energy for dissociation on the Pt/TiC. For NO reduction on the Pt/TiC surface, we have found that the direct dissociation mechanisms (NO + N + O → NO2 + N and NO + N + O → N2 + O + O) are easier with a smaller dissociation barrier than those on the Pt(111) surface; and the dimeric process (NO + NO → (NO)2 → N2O + O → N2 + O + O) is considered to be dominant or significant with even a lower energy barrier than that of the direct dissociation. The results show that Pt/TiC can serve as an efficient catalyst for NO reduction.

Disorganized attachment in young adulthood as a partial mediator of relations between severity of childhood abuse and dissociation.

PubMed

Byun, Sooyeon; Brumariu, Laura E; Lyons-Ruth, Karlen

2016-01-01

Disorganized attachment has been proposed as a mediating mechanism in the relation between childhood abuse and dissociation. However, support for mediation has been mixed when interview or self-report measures of attachment have been used. In the current work, relations among severity of abuse, attachment disorganization, and dissociation were assessed in young adulthood using both interview and interaction-based measures of attachment. A total of 112 low-income young adults were assessed for socioeconomic stresses, abusive experiences in childhood, and attachment disorganization at age 20. Attachment disorganization was assessed with the Adult Attachment Interview, coded independently for Unresolved states of mind and for Hostile-Helpless states of mind. Attachment disorganization was also measured using a newly validated assessment of young adult-parent interaction during a conflict discussion. Mediation analyses revealed that the link between childhood abuse and dissociation was partially explained by disturbances in young adult-parent interaction. Narrative disturbances on the Adult Attachment Interview were related to abuse and to dissociation but did not mediate the link between the two. Results are discussed in relation to the role of parent-child communication processes in pathways to dissociation.

Double dissociation between first- and second-order processing.

PubMed

Allard, Rémy; Faubert, Jocelyn

2007-04-01

To study the difference of sensitivity to luminance- (LM) and contrast-modulated (CM) stimuli, we compared LM and CM detection thresholds in LM- and CM-noise conditions. The results showed a double dissociation (no or little inter-attribute interaction) between the processing of these stimuli, which implies that both stimuli must be processed, at least at some point, by separate mechanisms and that both stimuli are not merged after a rectification process. A second experiment showed that the internal equivalent noise limiting the CM sensitivity was greater than the one limiting the carrier sensitivity, which suggests that the internal noise occurring before the rectification process is not limiting the CM sensitivity. These results support the hypothesis that a suboptimal rectification process partially explains the difference of LM and CM sensitivity.

Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakrabarty, Aurab, E-mail: aurab.chakrabarty@qatar.tamu.edu; Bouhali, Othmane; Mousseau, Normand

Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structuralmore » defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from finite-size effects.« less

Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

NASA Astrophysics Data System (ADS)

Chakrabarty, Aurab; Bouhali, Othmane; Mousseau, Normand; Becquart, Charlotte S.; El-Mellouhi, Fedwa

2016-08-01

Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structural defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from finite-size effects.

Imagining the future: The core episodic simulation network dissociates as a function of timecourse and the amount of simulated information

PubMed Central

Thakral, Preston P.; Benoit, Roland G.; Schacter, Daniel L.

2017-01-01

Neuroimaging data indicate that episodic memory (i.e., remembering specific past experiences) and episodic simulation (i.e., imagining specific future experiences) are associated with enhanced activity in a common set of neural regions, often referred to as the core network. This network comprises the hippocampus, parahippocampal cortex, lateral and medial parietal cortex, lateral temporal cortex, and medial prefrontal cortex. Evidence for a core network has been taken as support for the idea that episodic memory and episodic simulation are supported by common processes. Much remains to be learned about how specific core network regions contribute to specific aspects of episodic simulation. Prior neuroimaging studies of episodic memory indicate that certain regions within the core network are differentially sensitive to the amount of information recollected (e.g., the left lateral parietal cortex). In addition, certain core network regions dissociate as a function of their timecourse of engagement during episodic memory (e.g., transient activity in the posterior hippocampus and sustained activity in the left lateral parietal cortex). In the current study, we assessed whether similar dissociations could be observed during episodic simulation. We found that the left lateral parietal cortex modulates as a function of the amount of simulated details. Of particular interest, while the hippocampus was insensitive to the amount of simulated details, we observed a temporal dissociation within the hippocampus: transient activity occurred in relatively posterior portions of the hippocampus and sustained activity occurred in anterior portions. Because the posterior hippocampal and lateral parietal findings parallel those observed previously during episodic memory, the present results add to the evidence that episodic memory and episodic simulation are supported by common processes. Critically, the present study also provides evidence that regions within the core network support dissociable processes. PMID:28324695

Computational Study of Electron-Molecule Collisions Related to Low-Temperature Plasmas.

NASA Astrophysics Data System (ADS)

Huo, Winifred M.

1997-10-01

Computational study of electron-molecule collisions not only complements experimental measurements, but can also be used to investigate processes not readily accessible experimentally. A number of ab initio computational methods are available for this type of calculations. Here we describe a recently developed technique, the finite element Z-matrix method. Analogous to the R-matrix method, it partitions the space into regions and employs real matrix elements. However, unlike the implementation of the R-matrix method commonly used in atomic and molecular physics,(C. J. Gillan, J. Tennyson, and P. G. Burke, Chapter 10 in Computational Methods for Electron-Molecule Collisions), W. M. Huo and F. A. Gianturco, Editors, Plenum, New York (1995), p. 239. the Z-matrix method is fully variational.(D. Brown and J. C. Light, J. Chem. Phys. 101), 3723 (1994). In the present implementation, a mixed basis of finite elements and Gaussians is used to represent the continuum electron, thus offering full flexibility without imposing fixed boundary conditions. Numerical examples include the electron-impact dissociation of N2 via the metastable A^3Σ_u^+ state, a process which may be important in the lower thermosphere, and the dissociation of the CF radical, a process of interest to plasma etching. To understand the dissociation pathways, large scale quantum chemical calculations have been carried out for all target states which dissociate to the lowest five limits in the case of N_2, and to the lowest two limits in the case of CF. For N_2, the structural calculations clearly show the preference for predissociation if the initial state is the ground X^1Σ_g^+ state, but direct dissociation appears to be preferable if the initial state is the A^3Σ_u^+ state. Multi-configuration SCF target functions are used in the collisional calculation,

Native-language N400 and P600 predict dissociable language-learning abilities in adults.

PubMed

Qi, Zhenghan; Beach, Sara D; Finn, Amy S; Minas, Jennifer; Goetz, Calvin; Chan, Brian; Gabrieli, John D E

2017-04-01

Language learning aptitude during adulthood varies markedly across individuals. An individual's native-language ability has been associated with success in learning a new language as an adult. However, little is known about how native-language processing affects learning success and what neural markers of native-language processing, if any, are related to success in learning. We therefore related variation in electrophysiology during native-language processing to success in learning a novel artificial language. Event-related potentials (ERPs) were recorded while native English speakers judged the acceptability of English sentences prior to learning an artificial language. There was a trend towards a double dissociation between native-language ERPs and their relationships to novel syntax and vocabulary learning. Individuals who exhibited a greater N400 effect when processing English semantics showed better future learning of the artificial language overall. The N400 effect was related to syntax learning via its specific relationship to vocabulary learning. In contrast, the P600 effect size when processing English syntax predicted future syntax learning but not vocabulary learning. These findings show that distinct neural signatures of native-language processing relate to dissociable abilities for learning novel semantic and syntactic information. Copyright © 2016 Elsevier Ltd. All rights reserved.

The origins of levels-of-processing effects in a conceptual test: evidence for automatic influences of memory from the process-dissociation procedure.

PubMed

Bergerbest, Dafna; Goshen-Gottstein, Yonatan

2002-12-01

In three experiments, we explored automatic influences of memory in a conceptual memory task, as affected by a levels-of-processing (LoP) manipulation. We also explored the origins of the LoP effect by examining whether the effect emerged only when participants in the shallow condition truncated the perceptual processing (the lexical-processing hypothesis) or even when the entire word was encoded in this condition (the conceptual-processing hypothesis). Using the process-dissociation procedure and an implicit association-generation task, we found that the deep encoding condition yielded higher estimates of automatic influences than the shallow condition. In support of the conceptual processing hypothesis, the LoP effect was found even when the shallow task did not lead to truncated processing of the lexical units. We suggest that encoding for meaning is a prerequisite for automatic processing on conceptual tests of memory.

Electron beam induced deposition of silacyclohexane and dichlorosilacyclohexane: the role of dissociative ionization and dissociative electron attachment in the deposition process.

PubMed

P, Ragesh Kumar T; Hari, Sangeetha; Damodaran, Krishna K; Ingólfsson, Oddur; Hagen, Cornelis W

2017-01-01

We present first experiments on electron beam induced deposition of silacyclohexane (SCH) and dichlorosilacyclohexane (DCSCH) under a focused high-energy electron beam (FEBID). We compare the deposition dynamics observed when growing pillars of high aspect ratio from these compounds and we compare the proximity effect observed for these compounds. The two precursors show similar behaviour with regards to fragmentation through dissociative ionization in the gas phase under single-collision conditions. However, while DCSCH shows appreciable cross sections with regards to dissociative electron attachment, SCH is inert with respect to this process. We discuss our deposition experiments in context of the efficiency of these different electron-induced fragmentation processes. With regards to the deposition dynamics, we observe a substantially faster growth from DCSCH and a higher saturation diameter when growing pillars with high aspect ratio. However, both compounds show similar behaviour with regards to the proximity effect. With regards to the composition of the deposits, we observe that the C/Si ratio is similar for both compounds and in both cases close to the initial molecular stoichiometry. The oxygen content in the DCSCH deposits is about double that of the SCH deposits. Only marginal chlorine is observed in the deposits of from DCSCH. We discuss these observations in context of potential approaches for Si deposition.

Organic solar cells: understanding the role of Förster resonance energy transfer.

PubMed

Feron, Krishna; Belcher, Warwick J; Fell, Christopher J; Dastoor, Paul C

2012-12-12

Organic solar cells have the potential to become a low-cost sustainable energy source. Understanding the photoconversion mechanism is key to the design of efficient organic solar cells. In this review, we discuss the processes involved in the photo-electron conversion mechanism, which may be subdivided into exciton harvesting, exciton transport, exciton dissociation, charge transport and extraction stages. In particular, we focus on the role of energy transfer as described by F¨orster resonance energy transfer (FRET) theory in the photoconversion mechanism. FRET plays a major role in exciton transport, harvesting and dissociation. The spectral absorption range of organic solar cells may be extended using sensitizers that efficiently transfer absorbed energy to the photoactive materials. The limitations of F¨orster theory to accurately calculate energy transfer rates are discussed. Energy transfer is the first step of an efficient two-step exciton dissociation process and may also be used to preferentially transport excitons to the heterointerface, where efficient exciton dissociation may occur. However, FRET also competes with charge transfer at the heterointerface turning it in a potential loss mechanism. An energy cascade comprising both energy transfer and charge transfer may aid in separating charges and is briefly discussed. Considering the extent to which the photo-electron conversion efficiency is governed by energy transfer, optimisation of this process offers the prospect of improved organic photovoltaic performance and thus aids in realising the potential of organic solar cells.

An ERP Study of Good Production vis-à-vis Poor Perception of Tones in Cantonese: Implications for Top-Down Speech Processing

PubMed Central

Law, Sam-Po; Fung, Roxana; Kung, Carmen

2013-01-01

This study investigated a theoretically challenging dissociation between good production and poor perception of tones among neurologically unimpaired native speakers of Cantonese. The dissociation is referred to as the near-merger phenomenon in sociolinguistic studies of sound change. In a passive oddball paradigm, lexical and nonlexical syllables of the T1/T6 and T4/T6 contrasts were presented to elicit the mismatch negativity (MMN) and P3a from two groups of participants, those who could produce and distinguish all tones in the language (Control) and those who could produce all tones but specifically failed to distinguish between T4 and T6 in perception (Dissociation). The presence of MMN to T1/T6 and null response to T4/T6 of lexical syllables in the dissociation group confirmed the near-merger phenomenon. The observation that the control participants exhibited a statistically reliable MMN to lexical syllables of T1/T6, weaker responses to nonlexical syllables of T1/T6 and lexical syllables of T4/T6, and finally null response to nonlexical syllables of T4/T6, suggests the involvement of top-down processing in speech perception. Furthermore, the stronger P3a response of the control group, compared with the dissociation group in the same experimental conditions, may be taken to indicate higher cognitive capability in attention switching, auditory attention or memory in the control participants. This cognitive difference, together with our speculation that constant top-down predictions without complete bottom-up analysis of acoustic signals in speech recognition may reduce one’s sensitivity to small acoustic contrasts, account for the occurrence of dissociation in some individuals but not others. PMID:23342146

An ERP study of good production vis-à-vis poor perception of tones in Cantonese: implications for top-down speech processing.

PubMed

Law, Sam-Po; Fung, Roxana; Kung, Carmen

2013-01-01

This study investigated a theoretically challenging dissociation between good production and poor perception of tones among neurologically unimpaired native speakers of Cantonese. The dissociation is referred to as the near-merger phenomenon in sociolinguistic studies of sound change. In a passive oddball paradigm, lexical and nonlexical syllables of the T1/T6 and T4/T6 contrasts were presented to elicit the mismatch negativity (MMN) and P3a from two groups of participants, those who could produce and distinguish all tones in the language (Control) and those who could produce all tones but specifically failed to distinguish between T4 and T6 in perception (Dissociation). The presence of MMN to T1/T6 and null response to T4/T6 of lexical syllables in the dissociation group confirmed the near-merger phenomenon. The observation that the control participants exhibited a statistically reliable MMN to lexical syllables of T1/T6, weaker responses to nonlexical syllables of T1/T6 and lexical syllables of T4/T6, and finally null response to nonlexical syllables of T4/T6, suggests the involvement of top-down processing in speech perception. Furthermore, the stronger P3a response of the control group, compared with the dissociation group in the same experimental conditions, may be taken to indicate higher cognitive capability in attention switching, auditory attention or memory in the control participants. This cognitive difference, together with our speculation that constant top-down predictions without complete bottom-up analysis of acoustic signals in speech recognition may reduce one's sensitivity to small acoustic contrasts, account for the occurrence of dissociation in some individuals but not others.

Activation of Peptide ions by blackbody radiation: factors that lead to dissociation kinetics in the rapid energy exchange limit.

PubMed

Price, W D; Williams, E R

1997-11-20

Unimolecular rate constants for blackbody infrared radiative dissociation (BIRD) were calculated for the model protonated peptide (AlaGly)(n) (n = 2-32) using a variety of dissociation parameters. Combinations of dissociation threshold energies ranging from 0.8 to 1.7 eV and transition entropies corresponding to Arrhenius preexponential factors ranging from very "tight" (A(infinity) = 10(9.9) s(-1)) to "loose" (A(infinity) = 10(16.8) s(-1)) were selected to represent dissociation parameters within the experimental temperature range (300-520 K) and kinetic window (k(uni) = 0.001-0.20 s(-1)) typically used in the BIRD experiment. Arrhenius parameters were determined from the temperature dependence of these values and compared to those in the rapid energy exchange (REX) limit. In this limit, the internal energy of a population of ions is given by a Boltzmann distribution, and kinetics are the same as those in the traditional high-pressure limit. For a dissociation process to be in this limit, the rate of photon exchange between an ion and the vacuum chamber walls must be significantly greater than the dissociation rate. Kinetics rapidly approach the REX limit either as the molecular size or threshold dissociation energy increases or as the transition-state entropy or experimental temperature decreases. Under typical experimental conditions, peptide ions larger than 1.6 kDa should be in the REX limit. Smaller ions may also be in the REX limit depending on the value of the threshold dissociation energy and transition-state entropy. Either modeling or information about the dissociation mechanism must be known in order to confirm REX limit kinetics for these smaller ions. Three principal factors that lead to the size dependence of REX limit kinetics are identified. With increasing molecular size, rates of radiative absorption and emission increase, internal energy distributions become relatively narrower, and the microcanonical dissociation rate constants increase more slowly over the energy distribution of ions. Guidelines established here should make BIRD an even more reliable method to obtain information about dissociation energetics and mechanisms for intermediate size molecules.

Activation of Peptide Ions by Blackbody Radiation: Factors That Lead to Dissociation Kinetics in the Rapid Energy Exchange Limit

PubMed Central

Price, William D.

2005-01-01

Unimolecular rate constants for blackbody infrared radiative dissociation (BIRD) were calculated for the model protonated peptide (AlaGly)n (n = 2–32) using a variety of dissociation parameters. Combinations of dissociation threshold energies ranging from 0.8 to 1.7 eV and transition entropies corresponding to Arrhenius preexponential factors ranging from very “tight” (A∞ = 109.9 s−1) to “loose” (A∞ = 1016.8 s−1) were selected to represent dissociation parameters within the experimental temperature range (300–520 K) and kinetic window (kuni = 0.001–0.20 s−1) typically used in the BIRD experiment. Arrhenius parameters were determined from the temperature dependence of these values and compared to those in the rapid energy exchange (REX) limit. In this limit, the internal energy of a population of ions is given by a Boltzmann distribution, and kinetics are the same as those in the traditional high-pressure limit. For a dissociation process to be in this limit, the rate of photon exchange between an ion and the vacuum chamber walls must be significantly greater than the dissociation rate. Kinetics rapidly approach the REX limit either as the molecular size or threshold dissociation energy increases or as the transition-state entropy or experimental temperature decreases. Under typical experimental conditions, peptide ions larger than 1.6 kDa should be in the REX limit. Smaller ions may also be in the REX limit depending on the value of the threshold dissociation energy and transition-state entropy. Either modeling or information about the dissociation mechanism must be known in order to confirm REX limit kinetics for these smaller ions. Three principal factors that lead to the size dependence of REX limit kinetics are identified. With increasing molecular size, rates of radiative absorption and emission increase, internal energy distributions become relatively narrower, and the microcanonical dissociation rate constants increase more slowly over the energy distribution of ions. Guidelines established here should make BIRD an even more reliable method to obtain information about dissociation energetics and mechanisms for intermediate size molecules. PMID:16604162

Trait Dissociation and the Subjective Affective, Motivational, and Phenomenological Experience of Self-Defining Memories

PubMed Central

Sutin, Angelina R.; Stockdale, Gary D.

2010-01-01

The present research reports two studies that examine the relation between non-pathological trait dissociation and the subjective affect, motivation, and phenomenology of self-defining memories. In Study 1 (N=293), participants retrieved and rated the emotional and motivational experience of a general and a positive and negative achievement-related memory. Study 2 (N=449) extended these ratings to relationship-related memories and the phenomenological experience of the memory. Dissociation was associated with incongruent affect in valenced memories (e.g., positive affect in a negative memory) and memories that were visually incoherent and saturated with power motivation, hubristic pride, and shame, regardless of valence or domain. The present findings demonstrate that autobiographical memories, which integrate emotional, motivational, and phenomenological components, reflect the emotional and motivational processes inherent to dissociation. PMID:21204840

Observing electron localization in a dissociating H2+ molecule in real time

PubMed Central

Xu, H.; Li, Zhichao; He, Feng; Wang, X.; Atia-Tul-Noor, A.; Kielpinski, D.; Sang, R. T.; Litvinyuk, I. V.

2017-01-01

Dissociation of diatomic molecules with odd number of electrons always causes the unpaired electron to localize on one of the two resulting atomic fragments. In the simplest diatomic molecule H2+ dissociation yields a hydrogen atom and a proton with the sole electron ending up on one of the two nuclei. That is equivalent to breaking of a chemical bond—the most fundamental chemical process. Here we observe such electron localization in real time by performing a pump–probe experiment. We demonstrate that in H2+ electron localization is complete in just 15 fs when the molecule’s internuclear distance reaches 8 atomic units. The measurement is supported by a theoretical simulation based on numerical solution of the time-dependent Schrödinger equation. This observation advances our understanding of detailed dynamics of molecular dissociation. PMID:28621332

When concepts lose their color: A case of object color knowledge impairment

PubMed Central

Stasenko, Alena; Garcea, Frank E.; Dombovy, Mary; Mahon, Bradford Z.

2014-01-01

Color is important in our daily interactions with objects, and plays a role in both low- and high-level visual processing. Previous neuropsychological studies have shown that color perception and object-color knowledge can doubly dissociate, and that both can dissociate from processing of object form. We present a case study of an individual who displayed an impairment for knowledge of the typical colors of objects, with preserved color perception and color naming. Our case also presented with a pattern of, if anything, worse performance for naming living items compared to nonliving things. The findings of the experimental investigation are evaluated in light of two theories of conceptual organization in the brain: the Sensory Functional Theory and the Domain-Specific Hypothesis. The dissociations observed in this case compel a model in which sensory/motor modality and semantic domain jointly constrain the organization of object knowledge. PMID:25058612

Dissociating Stimulus-Set and Response-Set in the Context of Task-Set Switching

PubMed Central

Kieffaber, Paul D.; Kruschke, John K.; Cho, Raymond Y.; Walker, Philip M.; Hetrick, William P.

2014-01-01

The primary aim of the present research was to determine how stimulus-set and response-set components of task-set contribute to switch costs and conflict processing. Three experiments are described wherein participants completed an explicitly cued task-switching procedure. Experiment 1 established that task switches requiring a reconfiguration of both stimulus- and response-set incurred larger residual switch costs than task switches requiring the reconfiguration of stimulus-set alone. Between-task interference was also drastically reduced for response-set conflict compared with stimulus-set conflict. A second experiment replicated these findings and demonstrated that stimulus- and response-conflict have dissociable effects on the “decision time” and “motor time” components of total response time. Finally, a third experiment replicated Experiment 2 and demonstrated that the stimulus- and response- components of task switching and conflict processing elicit dissociable neural activity as evidence by event-related brain potentials. PMID:22984990

Simplified model to describe the dissociative recombination of linear polyatomic ions of astrophysical interest

NASA Astrophysics Data System (ADS)

Fonseca Dos Santos, Samantha; Douguet, Nicolas; Kokoouline, Viatcheslav; Orel, Ann

2013-05-01

We will present theoretical results on the dissociative recombination (DR) of the linear polyatomic ions HCNH+, HCO+ and N2H+. Besides their astrophysical importance, they also share the characteristic that at low electronic impact energies their DR process happens via the indirect DR mechanism. We apply a general simplified model successfully implemented to treat the DR process of the highly symmetric non-linear molecules H3+, CH3+, H3O+ and NH4+ to calculated cross sections and DR rates for these ions. The model is based on multichannel quantum defect theory and accounts for all the main ingredients of indirect DR. New perspectives on dissociative recombination of HCO+ will also be discussed, including the possible role of HOC+ in storage ring experimental results. This work is supported by the DOE Office of Basic Energy Science and the National Science Foundation, Grant No's PHY-11-60611 and PHY-10-68785.

Dissociations among functional subsystems governing melody recognition after right-hemisphere damage.

PubMed

Steinke, W R; Cuddy, L L; Jakobson, L S

2001-07-01

This study describes an amateur musician, KB, who became amusic following a right-hemisphere stroke. A series of assessments conducted post-stroke revealed that KB functioned in the normal range for most verbal skills. However, compared with controls matched in age and music training, KB showed severe loss of pitch and rhythmic processing abilities. His ability to recognise and identify familiar instrumental melodies was also lost. Despite these deficits, KB performed remarkably well when asked to recognise and identify familiar song melodies presented without accompanying lyrics. This dissociation between the ability to recognise/identify song vs. instrumental melodies was replicated across different sets of musical materials, including newly learned melodies. Analyses of the acoustical and musical features of song and instrumental melodies discounted an explanation of the dissociation based on these features alone. Rather, the results suggest a functional dissociation resulting from a focal brain lesion. We propose that, in the case of song melodies, there remains sufficient activation in KB's melody analysis system to coactivate an intact representation of both associative information and the lyrics in the speech lexicon, making recognition and identification possible. In the case of instrumental melodies, no such associative processes exist; thus recognition and identification do not occur.

Acid-base characterization of 5-hydroxypyrazine-2-carboxylic acid and the role of ionic equilibria in the optimization of some process conditions for its biocatalytic production.

PubMed

Sak-Bosnar, M; Kovar, K

2005-10-01

This paper describes the use of potentiometric titration to determine the relevant acid-base properties of 5-hydroxypyrazine-2-carboxylic acid (5OH-PYCA), an important intermediate in the production of tuberculostatics. The data obtained were used for calculation of the dissociation constants of 5OH-PYCA. It was found that 5OH-PYCA dissociates in two steps, with the corresponding dissociation constants pK (a1)=3.42 and pK (a2)=7.96, designating 5OH-PYCA as a medium weak acid (1st step). The distribution diagram of dissociated species and the buffer-strength diagram of 5OH-PYCA provide useful information about its behaviour at different pH. The ionic equilibria data obtained can be used for selection of the optimum pH for biotransformation of pyrazine-2-carboxylic acid (PYCA) and for prediction of pH changes during the biotransformation. These data can also be used for selection of the optimum pH for precipitating 5OH-PYCA in downstream processing. All computations have been optimized by mathematical modelling using Solver.

Comparison of electromagnetic and nuclear dissociation of 17Ne

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

Revealing the favorable dissociation pathway of type II kinase inhibitors via enhanced sampling simulations and two-end-state calculations.

PubMed

Sun, Huiyong; Tian, Sheng; Zhou, Shunye; Li, Youyong; Li, Dan; Xu, Lei; Shen, Mingyun; Pan, Peichen; Hou, Tingjun

2015-02-13

How does a type II inhibitor bind to/unbind from a kinase target is still a confusing question because the small molecule occupies both the ATP pocket and the allosteric pocket of the kinase binding site. Here, by using enhanced sampling simulations (umbrella sampling, US) and two-end-state free energy calculations (MM/GSBA), we systemically studied the dissociation processes of two distinct small molecules escaping from the binding pocket of p38 MAP kinase through the allosteric channel and the ATP channel. The results show that the unbinding pathways along the allosteric channel have much lower PMF depths than those along the ATP channel, suggesting that the allosteric channel is more favorable for the dissociations of the two inhibitors and thereby supporting the general understanding that the largest channel of a target is usually the entry/exit pathway for the binding/dissociation of small molecules. Interestingly, the MM/GBSA approach yielded similar PMF profiles compared with those based on US, a much time consuming approach, indicating that for a general study, such as detecting the important transition state of a ligand binding/unbinding process, MM/GBSA may be a feasible choice.

A comparison of conscious and automatic memory processes for picture and word stimuli: a process dissociation analysis.

PubMed

McBride, Dawn M; Anne Dosher, Barbara

2002-09-01

Four experiments were conducted to evaluate explanations of picture superiority effects previously found for several tasks. In a process dissociation procedure (Jacoby, 1991) with word stem completion, picture fragment completion, and category production tasks, conscious and automatic memory processes were compared for studied pictures and words with an independent retrieval model and a generate-source model. The predictions of a transfer appropriate processing account of picture superiority were tested and validated in "process pure" latent measures of conscious and unconscious, or automatic and source, memory processes. Results from both model fits verified that pictures had a conceptual (conscious/source) processing advantage over words for all tasks. The effects of perceptual (automatic/word generation) compatibility depended on task type, with pictorial tasks favoring pictures and linguistic tasks favoring words. Results show support for an explanation of the picture superiority effect that involves an interaction of encoding and retrieval processes.

What can individual differences reveal about face processing?

PubMed Central

Yovel, Galit; Wilmer, Jeremy B.; Duchaine, Brad

2014-01-01

Faces are probably the most widely studied visual stimulus. Most research on face processing has used a group-mean approach that averages behavioral or neural responses to faces across individuals and treats variance between individuals as noise. However, individual differences in face processing can provide valuable information that complements and extends findings from group-mean studies. Here we demonstrate that studies employing an individual differences approach—examining associations and dissociations across individuals—can answer fundamental questions about the way face processing operates. In particular these studies allow us to associate and dissociate the mechanisms involved in face processing, tie behavioral face processing mechanisms to neural mechanisms, link face processing to broader capacities and quantify developmental influences on face processing. The individual differences approach we illustrate here is a powerful method that should be further explored within the domain of face processing as well as fruitfully applied across the cognitive sciences. PMID:25191241

Beyond the dual pathway model: evidence for the dissociation of timing, inhibitory, and delay-related impairments in attention-deficit/hyperactivity disorder.

PubMed

Sonuga-Barke, Edmund; Bitsakou, Paraskevi; Thompson, Margaret

2010-04-01

The dual pathway model explains neuro-psychological heterogeneity in Attention Deficit/Hyperactivity Disorder (ADHD) in terms of dissociable cognitive and motivational deficits each affecting some but not other patients. We explore whether deficits in temporal processing might constitute a third dissociable neuropsychological component of ADHD. Nine tasks designed to tap three domains (inhibitory control, delay aversion and temporal processing) were administered to ADHD probands (n=71; ages 6 to 17 years), their siblings (n=71; 65 unaffected by ADHD) and a group of non-ADHD controls (n=50). IQ and working memory were measured. Temporal processing, inhibitory control and delay-related deficits represented independent neuropsychological components. ADHD children differed from controls on all factors. For ADHD patients, the co-occurrence of inhibitory, temporal processing and delay-related deficits was no greater than expected by chance with substantial groups of patients showing only one problem. Domain-specific patterns of familial co-segregation provided evidence for the validity of neuropsychological subgroupings. The current results illustrate the neuropsychological heterogeneity in ADHD and initial support for a triple pathway model. The findings need to be replicated in larger samples.

Radical molecule and ion-molecule mechanisms in the polymerization of hydrocarbons and chlorosilanes in R.F. plasmas at low pressures (below 1.0 Torr)

NASA Technical Reports Server (NTRS)

Avni, R.; Carmi, U.; Inspektor, A.; Rosenthal, I.

1984-01-01

The ion-molecule and the radical-molecule mechanisms are responsible for the dissociation of hydrocarbons, and chlorosilane monomers and the formation of polymerized species, respectively, in the plasma state of a RF discharge. In the plasma, of a mixture of monomer with Ar, the rate determining step for both dissociation and polymerization is governed by an ion-molecular type interaction. Additions of H2 or NH3 to the monomer Ar(+) mixture transforms the rate determining step from an ion-molecular interaction to a radical-molecule type interaction for both monomer dissociation and polymerization processes.

Radical and ion molecule mechanisms in the polymerization of hydrocarbons and chlorosilanes in RF plasmas at low pressures ( 1.0 torr)

NASA Technical Reports Server (NTRS)

Avni, R.; Carmi, U.; Inspektor, A.; Rosenthal, I.

1984-01-01

The ion-molecule and the radical-molecule mechanisms are responsible for the dissociation of hydrocarbons, and chlorosilane monomers and the formation of polymerized species, respectively, in the plasma state of a RF discharge. In the plasma, of a mixture of monomer with Ar, the rate determining step for both dissociation and polymerization is governed by an ion-molecular type interaction. Additions of H2 or NH3 to the monomer Ar(+) mixture transforms the rate determining step from an ion-molecular interaction to a radical-molecule type interaction for both monomer dissociation and polymerization processes.

Fuzzy-trace theory: dual processes in memory, reasoning, and cognitive neuroscience.

PubMed

Brainerd, C J; Reyna, V F

2001-01-01

Fuzzy-trace theory has evolved in response to counterintuitive data on how memory development influences the development of reasoning. The two traditional perspectives on memory-reasoning relations--the necessity and constructivist hypotheses--stipulate that the accuracy of children's memory for problem information and the accuracy of their reasoning are closely intertwined, albeit for different reasons. However, contrary to necessity, correlational and experimental dissociations have been found between children's memory for problem information that is determinative in solving certain problems and their solutions of those problems. In these same tasks, age changes in memory for problem information appear to be dissociated from age changes in reasoning. Contrary to constructivism, correlational and experimental dissociations also have been found between children's performance on memory tests for actual experience and memory tests for the meaning of experience. As in memory-reasoning studies, age changes in one type of memory performance do not seem to be closely connected to age changes in the other type of performance. Subsequent experiments have led to dual-process accounts in both the memory and reasoning spheres. The account of memory development features four other principles: parallel verbatim-gist storage, dissociated verbatim-gist retrieval, memorial bases of conscious recollection, and identity/similarity processes. The account of the development of reasoning features three principles: gist extraction, fuzzy-to-verbatim continua, and fuzzy-processing preferences. The fuzzy-processing preference is a particularly important notion because it implies that gist-based intuitive reasoning often suffices to deliver "logical" solutions and that such reasoning confers multiple cognitive advantages that enhance accuracy. The explanation of memory-reasoning dissociations in cognitive development then falls out of fuzzy-trace theory's dual-process models of memory and reasoning. More explicitly, in childhood reasoning tasks, it is assumed that both verbatim and gist traces of problem information are stored. Responding accurately to memory tests for presented problem information depends primarily on verbatim memory abilities (preserving traces of that information and accessing them when the appropriate memory probes are administered). However, accurate solutions to reasoning problems depend primarily on gist-memory abilities (extracting the correct gist from problem information, focusing on that gist during reasoning, and accessing reasoning operations that process that gist). Because verbatim and gist memories exhibit considerable dissociation, both during storage and when they are subsequently accessed on memory tests, dissociations of verbatim-based memory performance from gist-based reasoning are predictable. Conversely, associations are predicted in situations in which memory and reasoning are based on the same verbatim traces (Brainerd & Reyna, 1988) and in situations in which memory and reasoning are based on the same gist traces (Reyna & Kiernan, 1994). Fuzzy-trace theory's memory and reasoning principles have been applied in other research domains. Four such domains are developmental cognitive neuroscience studies of false memory, studies of false memory in brain-damaged patients, studies of reasoning errors in judgment and decision making, and studies of retrieval mechanisms in recall. In the first domain, the principles of parallel verbatim-gist storage, dissociated verbatim-gist retrieval, and identity/similarity processes have been used to explain both spontaneous and implanted false reports in children and in the elderly. These explanations have produced some surprising predictions that have been verified: false reports do not merely decline with age during childhood but increase under theoretically specified conditions; reports of events that were not experienced can nevertheless be highly persistent over time; and false reports can be suppressed by retrieving verbatim traces of corresponding true events. In the second domain, the same principles have been invoked to explain why some forms of brain damage lead to elevated levels of false memory and other forms lead to reduced levels of false memory. In the third domain, the principles of gist extraction, fuzzy-to-verbatim continua, and fuzzy-processing preferences have been exploited to formulate a general theory of loci of processing failures in judgment and decision making, cluminating in a developmental account of degrees of rationality that distinguishes more and less advanced reasoning. This theory has in turn been used to formulate local models, such as the inclusion illusions model, that explain the characteristic reasoning errors that are observed on specific judgment and decision-making tasks. Finally, in the fourth domain, a dual-process conception of recall has been derived from the principles of parallel verbatim-gist storage and dissociated verbatim-gist retrieval. In this conception, which has been used to explain cognitive triage effects in recall and robust false recall, targets are recalled either by directly accessing their verbatim traces and reading the retrieved information out of consciousness or by reconstructively processing their gist traces.

Use of Computed X-ray Tomographic Data for Analyzing the Thermodynamics of a Dissociating Porous Sand/Hydrate Mixture

DOE R&D Accomplishments Database

Freifeld, Barry M.; Kneafsey, Timothy J.; Tomutsa, Liviu; Stern, Laura A.; Kirby, Stephen H.

2002-02-28

X-ray computed tomography (CT) is a method that has been used extensively in laboratory experiments for measuring rock properties and fluid transport behavior. More recently, CT scanning has been applied successfully to detect the presence and study the behavior of naturally occurring hydrates. In this study, we used a modified medical CT scanner to image and analyze the progression of a dissociation front in a synthetic methane hydrate/sand mixture. The sample was initially scanned under conditions at which the hydrate is stable (atmospheric pressure and liquid nitrogen temperature, 77 K). The end of the sample holder was then exposed to the ambient air, and the core was continuously scanned as dissociation occurred in response to the rising temperature. CT imaging captured the advancing dissociation front clearly and accurately. The evolved gas volume was monitored as a function of time. Measured by CT, the advancing hydrate dissociation front was modeled as a thermal conduction problem explicitly incorporating the enthalpy of dissociation, using the Stefan moving-boundary-value approach. The assumptions needed to perform the analysis consisted of temperatures at the model boundaries. The estimated value for thermal conductivity of 2.6 W/m K for the remaining water ice/sand mixture is higher than expected based on conduction alone; this high value may represent a lumped parameter that incorporates the processes of heat conduction, methane gas convection, and any kinetic effects that occur during dissociation. The technique presented here has broad implications for future laboratory and field testing that incorporates geophysical techniques to monitor gas hydrate dissociation.

Fate of MgSiO3 Post-Perovskite at Terapascal Pressures

NASA Astrophysics Data System (ADS)

Wentzcovitch, R. M.; Umemoto, K.; Wu, S.; Ho, K. M.; Ji, M.; Wang, C. Z.

2016-12-01

Understanding the fate of MgSiO3 post-perovskite (ppv) under TPa pressures should provide insights into the nature of the interiors of Super-Earths-type exoplanets. The prediction that ppv should dissociate into the elementary oxides MgO and SiO2 at TPa pressures [1] has been confirmed by all ab initio computational studies so far [2-4]. The most recent high pressure and high temperature (PT) studies agree that at 2.2 TPa the dissociation process should be completed [2,3]. These studies also agree that the final dissociation phase boundary has a negative Clapeyron slope [1-3], irrespective of the dissociation paths, suggesting a barrier to whole mantle convection possibly leading to chemical stratification in the deep mantle of these planets. The dissociation paths identified more recently [2-4] involve partial dissociation into MgO, SiO2, and Mg- and Si-rich intermediate compounds whose compositions are temperature dependent. Here we re-investigate the high PT phase diagram of the MgO-SiO2 system and identify novel phase fields and dissociation paths that push the final dissociation boundary to 3 TPa. 1) K. Umemoto, R. M. Wentzcovitch, & P. B. Allen, Dissociation of MgSiO3 in the cores of Gas Giants and Terrestrial Exoplanets, Science 311, 983 (2006). 2) K. Umemoto & R. M. Wentzcovitch, Two-stage dissociation of MgSiO3 post- perovskite, Earth & Planet. Sc. Lett. 311, 225 (2011). 3) H. Niu, A. R. Oganov, X.-C. Chen, & D. Li, Prediction of novel stable compounds in the Mg-Si-O system under exoplanet pressures, Sc. Rep. 5, 18347 (2015). 4) S. Q. Wu, M. Ji, C. Z. Wang, M. C. Nguye, X. Zhao, K. Umemoto, R. M. Wentzcovitch, & K. M. Ho, Adaptive genetic algorithm for crystal structure prediction, J. Phys.: Condens. Matter 26, 035402 (2014).

Force and Stress along Simulated Dissociation Pathways of Cucurbituril-Guest Systems.

PubMed

Velez-Vega, Camilo; Gilson, Michael K

2012-03-13

The field of host-guest chemistry provides computationally tractable yet informative model systems for biomolecular recognition. We applied molecular dynamics simulations to study the forces and mechanical stresses associated with forced dissociation of aqueous cucurbituril-guest complexes with high binding affinities. First, the unbinding transitions were modeled with constant velocity pulling (steered dynamics) and a soft spring constant, to model atomic force microscopy (AFM) experiments. The computed length-force profiles yield rupture forces in good agreement with available measurements. We also used steered dynamics with high spring constants to generate paths characterized by a tight control over the specified pulling distance; these paths were then equilibrated via umbrella sampling simulations and used to compute time-averaged mechanical stresses along the dissociation pathways. The stress calculations proved to be informative regarding the key interactions determining the length-force profiles and rupture forces. In particular, the unbinding transition of one complex is found to be a stepwise process, which is initially dominated by electrostatic interactions between the guest's ammoniums and the host's carbonyl groups, and subsequently limited by the extraction of the guest's bulky bicyclooctane moiety; the latter step requires some bond stretching at the cucurbituril's extraction portal. Conversely, the dissociation of a second complex with a more slender guest is mainly driven by successive electrostatic interactions between the different guest's ammoniums and the host's carbonyl groups. The calculations also provide information on the origins of thermodynamic irreversibilities in these forced dissociation processes.

Significant Quantum Effects in Hydrogen Activation

DOE PAGES

Kyriakou, Georgios; Davidson, Erlend R. M.; Peng, Guowen; ...

2014-03-31

Dissociation of molecular hydrogen is an important step in a wide variety of chemical, biological, and physical processes. Due to the light mass of hydrogen, it is recognized that quantum effects are often important to its reactivity. However, understanding how quantum effects impact the reactivity of hydrogen is still in its infancy. Here, we examine this issue using a well-defined Pd/Cu(111) alloy that allows the activation of hydrogen and deuterium molecules to be examined at individual Pd atom surface sites over a wide range of temperatures. Experiments comparing the uptake of hydrogen and deuterium as a function of temperature revealmore » completely different behavior of the two species. The rate of hydrogen activation increases at lower sample temperature, whereas deuterium activation slows as the temperature is lowered. Density functional theory simulations in which quantum nuclear effects are accounted for reveal that tunneling through the dissociation barrier is prevalent for H 2 up to ~190 K and for D 2 up to ~140 K. Kinetic Monte Carlo simulations indicate that the effective barrier to H 2 dissociation is so low that hydrogen uptake on the surface is limited merely by thermodynamics, whereas the D 2 dissociation process is controlled by kinetics. These data illustrate the complexity and inherent quantum nature of this ubiquitous and seemingly simple chemical process. Here, examining these effects in other systems with a similar range of approaches may uncover temperature regimes where quantum effects can be harnessed, yielding greater control of bond-breaking processes at surfaces and uncovering useful chemistries such as selective bond activation or isotope separation.« less

Murine Ia-associated invariant chain's processing to complex oligosaccharide forms and its dissociation from the I-Ak complex.

PubMed

Holt, G D; Swiedler, S J; Freed, J H; Hart, G W

1985-07-01

The processing of murine invariant chain (Ii) to a cell surface form bearing complex N-linked oligosaccharides has been demonstrated in the B cell lymphoma, AKTB-1b. In addition, the rate of processing of pulse-labeled Ii has been determined relative to its rate of dissociation from the alpha/beta complex of I-Ak. Ii, alpha-, and beta-chains were immunoprecipitated with anti-I-Ak or anti-Ii monoclonal antibodies. The heretofore uncharacterized complex oligosaccharide form of Ii (Ii-c) was identified in gel-purified immunoprecipitates by peptide mapping with reverse-phase HPLC. Ii-c is resistant to deglycosylation by Endo H, which is specific for high-mannose N-linkages, but can be digested with Endo F, a glycosidase capable of cleaving both complex and high-mannose N-linked oligosaccharides. Immunoprecipitation of surface iodinated cells indicates that Ii-c is expressed on the plasma membrane. Pulse-chase metabolic labeling data show that the processing of Ii to Ii-c occurs with a t1/2 of about 120 min. In contrast, the processing of both alpha- and beta-chains of I-Ak to complex forms occurs with a t1/2 of 15 to 20 min. Our data show that Ii-hm begins to dissociate rapidly from the I-Ak complex after 100 to 120 min of chase. Only a small amount (less than 5% on a per mole basis) of Ii-c was found associated with the I-Ak complexes after 300 min of continuous metabolic labeling. These results are consistent with Ii serving as a carrier for Ia antigens as they are transported to the cell surface. In addition, they suggest that the processing of Ii to Ii-c, or a late processing event of the alpha- and beta-chains, such as their sialylation, may be a possible mechanism for inducing the dissociation of Ii from the I-Ak complex.

Dissolution of Lignocelluloses with a High Lignin Content in a N-Methylmorpholine-N-oxide Monohydrate Solvent System via Simple Glycerol-Swelling and Mechanical Pretreatments.

PubMed

Zhang, Lili; Lu, Hailong; Yu, Juan; Wang, Zhiguo; Fan, Yimin; Zhou, Xiaofan

2017-11-08

Lignocelluloses (LCs) with various amounts of lignin (even as high as 18.4%) were successfully dissolved in N-methylmorpholine-N-oxide monohydrate (NMMO/H 2 O) solution with stirring at 85 °C within 5 h. For the developmental dissolution methods of LCs with a high lignin content in NMMO/H 2 O solution, the following two pretreatment steps of LCs were necessary: (1) glycerol swelling and (2) mechanical extrusion. The mechanical extrusion pretreatment under glycerol swelling dissociated the fiber bundles of LCs to thinner fibers and, thus, enhanced the accessibility and solubility of the LCs in NMMO/H 2 O. The crystal structure of the pretreated LCs had no significant transformation during pretreatment, while the diameters of the fiber bundles were reduced from 50-60 to 10-12 μm, as investigated by X-ray diffraction and scanning electron microscopy. After the dissolution-regeneration process of LCs, the fiber bundles of the LCs disappeared and the crystal type of cellulose in the LCs was transformed from cellulose I to cellulose II, which indicated the complete dissolution of LCs.

Aggregation and Gelation of Aromatic Polyamides with Parallel and Anti-parallel Alignment of Molecular Dipole Along the Backbone

NASA Astrophysics Data System (ADS)

Zhu, Dan; Shang, Jing; Ye, Xiaodong; Shen, Jian

2016-12-01

The understanding of macromolecular structures and interactions is important but difficult, due to the facts that a macromolecules are of versatile conformations and aggregate states, which vary with environmental conditions and histories. In this work two polyamides with parallel or anti-parallel dipoles along the linear backbone, named as ABAB (parallel) and AABB (anti-parallel) have been studied. By using a combination of methods, the phase behaviors of the polymers during the aggregate and gelation, i.e., the forming or dissociation processes of nuclei and fibril, cluster of fibrils, and cluster-cluster aggregation have been revealed. Such abundant phase behaviors are dominated by the inter-chain interactions, including dispersion, polarity and hydrogen bonding, and correlatd with the solubility parameters of solvents, the temperature, and the polymer concentration. The results of X-ray diffraction and fast-mode dielectric relaxation indicate that AABB possesses more rigid conformation than ABAB, and because of that AABB aggregates are of long fibers while ABAB is of hairy fibril clusters, the gelation concentration in toluene is 1 w/v% for AABB, lower than the 3 w/v% for ABAB.

Stability of iron-bearing carbonates in the deep Earth’s interior

DOE PAGES

Cerantola, Valerio; Bykova, Elena; Kupenko, Ilya; ...

2017-07-19

The presence of carbonates in inclusions in diamonds coming from depths exceeding 670 km are obvious evidence that carbonates exist in the Earth’s lower mantle. However, their range of stability, crystal structures and the thermodynamic conditions of the decarbonation processes remain poorly constrained. We investigate the behaviour of pure iron carbonate at pressures over 100 GPa and temperatures over 2,500 K using single-crystal X-ray diffraction and Mossbauer spectroscopy in laser-heated diamond anvil cells. On heating to temperatures of the Earth’s geotherm at pressures to B 50 GPa FeCO 3 partially dissociates to form various iron oxides. Furthermore, at higher pressures FeCO 3 forms two new structures— tetrairon(III) orthocarbonate Femore » $$3+\\atop{4}$$C 3O 12 and diiron(II) diiron(III) tetracarbonate Fe$$2+\\atop{2}$$ Fe$$3+\\atop{2}$$C 4 O 13, both phases containing CO 4 tetrahedra. Fe 4 C 4 O 13 is stable at conditions along the entire geotherm to depths of at least 2,500 km, thus demonstrating that self-oxidation-reduction reactions can preserve carbonates in the Earth’s lower mantle.« less

In Situ Graphene Growth Dynamics on Polycrystalline Catalyst Foils

PubMed Central

2016-01-01

The dynamics of graphene growth on polycrystalline Pt foils during chemical vapor deposition (CVD) are investigated using in situ scanning electron microscopy and complementary structural characterization of the catalyst with electron backscatter diffraction. A general growth model is outlined that considers precursor dissociation, mass transport, and attachment to the edge of a growing domain. We thereby analyze graphene growth dynamics at different length scales and reveal that the rate-limiting step varies throughout the process and across different regions of the catalyst surface, including different facets of an individual graphene domain. The facets that define the domain shapes lie normal to slow growth directions, which are determined by the interfacial mobility when attachment to domain edges is rate-limiting, as well as anisotropy in surface diffusion as diffusion becomes rate-limiting. Our observations and analysis thus reveal that the structure of CVD graphene films is intimately linked to that of the underlying polycrystalline catalyst, with both interfacial mobility and diffusional anisotropy depending on the presence of step edges and grain boundaries. The growth model developed serves as a general framework for understanding and optimizing the growth of 2D materials on polycrystalline catalysts. PMID:27576749

Dissociated emergent-response system and fine-processing system in human neural network and a heuristic neural architecture for autonomous humanoid robots.

PubMed

Yan, Xiaodan

2010-01-01

The current study investigated the functional connectivity of the primary sensory system with resting state fMRI and applied such knowledge into the design of the neural architecture of autonomous humanoid robots. Correlation and Granger causality analyses were utilized to reveal the functional connectivity patterns. Dissociation was within the primary sensory system, in that the olfactory cortex and the somatosensory cortex were strongly connected to the amygdala whereas the visual cortex and the auditory cortex were strongly connected with the frontal cortex. The posterior cingulate cortex (PCC) and the anterior cingulate cortex (ACC) were found to maintain constant communication with the primary sensory system, the frontal cortex, and the amygdala. Such neural architecture inspired the design of dissociated emergent-response system and fine-processing system in autonomous humanoid robots, with separate processing units and another consolidation center to coordinate the two systems. Such design can help autonomous robots to detect and respond quickly to danger, so as to maintain their sustainability and independence.

Highly efficient and autocatalytic H2₂ dissociation for CO₂ reduction into formic acid with zinc.

PubMed

Jin, Fangming; Zeng, Xu; Liu, Jianke; Jin, Yujia; Wang, Lunying; Zhong, Heng; Yao, Guodong; Huo, Zhibao

2014-03-28

Artificial photosynthesis, specifically H2O dissociation for CO2 reduction with solar energy, is regarded as one of the most promising methods for sustainable energy and utilisation of environmental resources. However, a highly efficient conversion still remains extremely challenging. The hydrogenation of CO2 is regarded as the most commercially feasible method, but this method requires either exotic catalysts or high-purity hydrogen and hydrogen storage, which are regarded as an energy-intensive process. Here we report a highly efficient method of H2O dissociation for reducing CO2 into chemicals with Zn powder that produces formic acid with a high yield of approximately 80%, and this reaction is revealed for the first time as an autocatalytic process in which an active intermediate, ZnH(-) complex, serves as the active hydrogen. The proposed process can assist in developing a new concept for improving artificial photosynthetic efficiency by coupling geochemistry, specifically the metal-based reduction of H2O and CO2, with solar-driven thermochemistry for reducing metal oxide into metal.

A functional dissociation of conflict processing within anterior cingulate cortex.

PubMed

Kim, Chobok; Kroger, James K; Kim, Jeounghoon

2011-02-01

Goal-directed behavior requires cognitive control to regulate the occurrence of conflict. The dorsal anterior cingulate cortex (dACC) has been suggested in detecting response conflict during various conflict tasks. Recent findings, however, have indicated not only that two distinct subregions of dACC are involved in conflict processing but also that the conflict occurs at both perceptual and response levels. In this study, we sought to examine whether perceptual and response conflicts are functionally dissociated in dACC. Thirteen healthy subjects performed a version of the Stroop task during functional magnetic resonance imaging (fMRI) scanning. We identified a functional dissociation of the caudal dACC (cdACC) and the rostral dACC (rdACC) in their responses to different sources of conflict. The cdACC was selectively engaged in perceptual conflict whereas the rdACC was more active in response conflict. Further, the dorsolateral prefrontal cortex (DLPFC) was coactivated not with cdACC but with rdACC. We suggest that cdACC plays an important role in regulative processing of perceptual conflict whereas rdACC is involved in detecting response conflict. Copyright © 2010 Wiley-Liss, Inc.

Highly efficient and autocatalytic H2O dissociation for CO2 reduction into formic acid with zinc

PubMed Central

Jin, Fangming; Zeng, Xu; Liu, Jianke; Jin, Yujia; Wang, Lunying; Zhong, Heng; Yao, Guodong; Huo, Zhibao

2014-01-01

Artificial photosynthesis, specifically H2O dissociation for CO2 reduction with solar energy, is regarded as one of the most promising methods for sustainable energy and utilisation of environmental resources. However, a highly efficient conversion still remains extremely challenging. The hydrogenation of CO2 is regarded as the most commercially feasible method, but this method requires either exotic catalysts or high-purity hydrogen and hydrogen storage, which are regarded as an energy-intensive process. Here we report a highly efficient method of H2O dissociation for reducing CO2 into chemicals with Zn powder that produces formic acid with a high yield of approximately 80%, and this reaction is revealed for the first time as an autocatalytic process in which an active intermediate, ZnH− complex, serves as the active hydrogen. The proposed process can assist in developing a new concept for improving artificial photosynthetic efficiency by coupling geochemistry, specifically the metal-based reduction of H2O and CO2, with solar-driven thermochemistry for reducing metal oxide into metal. PMID:24675820

Dissociative electron attachments to ethanol and acetaldehyde: A combined experimental and simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xu-Dong; Xuan, Chuan-Jin; Feng, Wen-Ling

Dissociation dynamics of the temporary negative ions of ethanol and acetaldehyde formed by the low-energy electron attachments is investigated by using the anion velocity map imaging technique and ab initio molecular dynamics simulations. The momentum images of the dominant fragments O{sup −}/OH{sup −} and CH{sub 3}{sup −} are recorded, indicating the low kinetic energies of O{sup −}/OH{sup −} for ethanol while the low and high kinetic energy distributions of O{sup −} ions for acetaldehyde. The CH{sub 3}{sup −} image for acetaldehyde also shows the low kinetic energy. With help of the dynamics simulations, the fragmentation processes are qualitatively clarified. Amore » new cascade dissociation pathway to produce the slow O{sup −} ion via the dehydrogenated intermediate, CH{sub 3}CHO{sup −} (acetaldehyde anion), is proposed for the dissociative electron attachment to ethanol. After the electron attachment to acetaldehyde molecule, the slow CH{sub 3}{sup −} is produced quickly in the two-body dissociation with the internal energy redistributions in different aspects before bond cleavages.« less

Molecular Basis of Ligand Dissociation from G Protein-Coupled Receptors and Predicting Residence Time.

PubMed

Guo, Dong; IJzerman, Adriaan P

2018-01-01

G protein-coupled receptors (GPCRs) are integral membrane proteins and represent the largest class of drug targets. During the past decades progress in structural biology has enabled the crystallographic elucidation of the architecture of these important macromolecules. It also provided atomic-level visualization of ligand-receptor interactions, dramatically boosting the impact of structure-based approaches in drug discovery. However, knowledge obtained through crystallography is limited to static structural information. Less information is available showing how a ligand associates with or dissociates from a given receptor, whose importance is in fact increasingly recognized by the drug research community. Owing to recent advances in computer power and algorithms, molecular dynamics stimulations have become feasible that help in analyzing the kinetics of the ligand binding process. Here, we review what is currently known about the dynamics of GPCRs in the context of ligand association and dissociation, as determined through both crystallography and computer simulations. We particularly focus on the molecular basis of ligand dissociation from GPCRs and provide case studies that predict ligand dissociation pathways and residence time.

Incorporation of {sup 13}C-labeled intermediates into developing lignin revealed by analytical pyrolysis and CuO oxidation in combination with IRM-GC-MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eglinton, T.I.; Goni, M.A.; Boon, J.J.

1995-12-31

Tissue samples from Ginkgo shoots (Ginkgo biloba L.) and Rice grass (Oryzasitiva sp.) incubated in the presence of {sup 13}C-labeled substrates such as coniferin (postulated to be biosynthetic intermediates in lignin biosynthesis) were studied using thermal and chemical dissociation methods in combination with molecular-level isotopic measurements. The aim of the study was (1) to investigate dissociation mechanisms, and (2) to examine and quantify the proportions of labeled material incorporated within each sample. Isotopic analysis of specific dissociation products revealed the presence of the label in its original positions, and only within lignin-derived (phenolic) products. Moreover, the distribution and isotopic compositionmore » of the dissociation products strongly suggest an origin from newly-formed lignin. These results clearly indicate that there is no {open_quotes}scrambling{close_quotes} of carbon atoms as a result of the dissociation process, thereby lending support to this analytical approach. In addition, the data provide confidence in the selective labeling approach for elucidation of the structure and biosynthesis of lignin.« less

Dissociations between Expectancy and Performance in Simple and Two-Choice Reaction-Time Tasks: A Test of Associative and Nonassociative Explanations

ERIC Educational Resources Information Center

Barrett, Louise C.; Livesey, Evan J.

2010-01-01

Perruchet, Cleeremans, and Destrebecqz (2006) reported a striking dissociation between trends in the conscious expectancy of an event and the speed of a response that is cued by that event. They argued that this indicates the operation of independent processes in human associative learning. However, there remains a strong possibility that this…

EEG and chaos: Description of underlying dynamics and its relation to dissociative states

NASA Technical Reports Server (NTRS)

Ray, William J.

1994-01-01

The goal of this work is the identification of states especially as related to the process of error production and lapses of awareness as might be experienced during aviation. Given the need for further articulation of the characteristics of 'error prone state' or 'hazardous state of awareness,' this NASA grant focused on basic ground work for the study of the psychophysiology of these states. In specific, the purpose of this grant was to establish the necessary methodology for addressing three broad questions. The first is how the error prone state should be conceptualized, and whether it is similar to a dissociative state, a hypnotic state, or absent mindedness. Over 1200 subjects completed a variety of psychometric measures reflecting internal states and proneness to mental lapses and absent mindedness; the study suggests that there exists a consistency of patterns displayed by individuals who self-report dissociative experiences such that those individuals who score high on measures of dissociation also score high on measures of absent mindedness, errors, and absorption, but not on scales of hypnotizability. The second broad question is whether some individuals are more prone to enter these states than others. A study of 14 young adults who scored either high or low on the dissociation experiences scale performed a series of six tasks. This study suggests that high and low dissociative individuals arrive at the experiment in similar electrocortical states and perform cognitive tasks (e.g., mental math) in a similar manner; it is in the processing of internal emotional states that differences begin to emerge. The third question to be answered is whether recent research in nonlinear dynamics, i.e., chaos, offer an addition and/or alternative to traditional signal processing methods, i.e., fast Fourier transforms, and whether chaos procedures can be modified to offer additional information useful in identifying brain states. A preliminary review suggests that current nonlinear dynamical techniques such as dimensional analysis can be successfully applied to electrocortical activity. Using the data set developed in the study of the young adults, chaos analyses using the Farmer algorithm were performed; it is concluded that dimensionality measures reflect information not contained in traditional EEG Fourier analysis.

A combined thermal dissociation and electron impact ionization source for RIB generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alton, G.D.; Williams, C.

1995-12-31

The probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecular feed materials with conventional, hot-cathode, electron-impact ion sources is low and consequently, the ion beams from these sources often appear as mixtures of several molecular sideband beams. This fragmentation process leads to dilution of the intensity of the species of interest for RIB applications where beam intensity is at a premium. We have conceived an ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high ionization efficiency characteristics of an electron impact ionization source that will, in principle, overcome thismore » handicap. The source concept will be evaluated as a potential candidate for use for RIB generation at the Holifield Radioactive Ion Beam Facility (HRIBF), now under construction at the Oak Ridge National Laboratory. The design features and principles of operation of the source are described in this article.« less

Dissociative recombination by frame transformation to Siegert pseudostates: A comparison with a numerically solvable model

NASA Astrophysics Data System (ADS)

Hvizdoš, Dávid; Váňa, Martin; Houfek, Karel; Greene, Chris H.; Rescigno, Thomas N.; McCurdy, C. William; Čurík, Roman

2018-02-01

We present a simple two-dimensional model of the indirect dissociative recombination process. The model has one electronic and one nuclear degree of freedom and it can be solved to high precision, without making any physically motivated approximations, by employing the exterior complex scaling method together with the finite-elements method and discrete variable representation. The approach is applied to solve a model for dissociative recombination of H2 + in the singlet ungerade channels, and the results serve as a benchmark to test validity of several physical approximations commonly used in the computational modeling of dissociative recombination for real molecular targets. The second, approximate, set of calculations employs a combination of multichannel quantum defect theory and frame transformation into a basis of Siegert pseudostates. The cross sections computed with the two methods are compared in detail for collision energies from 0 to 2 eV.

Hypnotizability in acute stress disorder.

PubMed

Bryant, R A; Guthrie, R M; Moulds, M L

2001-04-01

This study investigated the relationship between acute dissociative reactions to trauma and hypnotizability. Acutely traumatized patients (N=61) with acute stress disorder, subclinical acute stress disorder (no dissociative symptoms), and no acute stress disorder were administered the Stanford Hypnotic Clinical Scale within 4 weeks of their trauma. Although patients with acute stress disorder and patients with subclinical acute stress disorder displayed comparable levels of nondissociative psychopathology, acute stress disorder patients had higher levels of hypnotizability and were more likely to display reversible posthypnotic amnesia than both patients with subclinical acute stress disorder and patients with no acute stress disorder. The findings may be interpreted in light of a diathesis-stress process mediating trauma-related dissociation. People who develop acute stress disorder in response to traumatic experience may have a stronger ability to experience dissociative phenomena than people who develop subclinical acute stress disorder or no acute stress disorder.

Control of photodissociation and photoionization of the NaI molecule by dynamic Stark effect.

PubMed

Han, Yong-Chang; Yuan, Kai-Jun; Hu, Wen-Hui; Cong, Shu-Lin

2009-01-28

The diabatic photodissociation and photoionization processes of the NaI molecule are studied theoretically using the quantum wave packet method. A pump laser pulse is used to prepare a dissociation wave packet that propagates through both the ionic channel (NaI-->Na(+)+I(-)) and the covalent channel (NaI-->Na+I). A Stark pulse is used to control the diabatic dissociation dynamics and a probe pulse is employed to ionize the products from the two channels. Based on the first order nonresonant nonperturbative dynamic Stark effect, the dissociation probabilities and the branching ratio of the products from the two channels can be controlled. Moreover the final photoelectron kinetic energy distribution can also be affected by the Stark pulse. The influences of the delay time, intensity, frequency, and carrier-envelope phase of the Stark pulse on the dissociation and ionization dynamics of the NaI molecule are discussed in detail.

Visualizing and Steering Dissociative Frustrated Double Ionization of Hydrogen Molecules

NASA Astrophysics Data System (ADS)

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

2017-12-01

We experimentally visualize the dissociative frustrated double ionization of hydrogen molecules by using few-cycle laser pulses in a pump-probe scheme, in which process the tunneling ionized electron is recaptured by one of the outgoing nuclei of the breaking molecule. Three internuclear distances are recognized to enhance the dissociative frustrated double ionization of molecules at different instants after the first ionization step. The recapture of the electron can be further steered to one of the outgoing nuclei as desired by using phase-controlled two-color laser pulses. Both the experimental measurements and numerical simulations suggest that the Rydberg atom is favored to emit to the direction of the maximum of the asymmetric optical field. Our results on the one hand intuitively visualize the dissociative frustrated double ionization of molecules, and on the other hand open the possibility to selectively excite the heavy fragment ejected from a molecule.

Functional brain imaging in 14 patients with dissociative amnesia reveals right inferolateral prefrontal hypometabolism.

PubMed

Brand, Matthias; Eggers, Carsten; Reinhold, Nadine; Fujiwara, Esther; Kessler, Josef; Heiss, Wolf-Dieter; Markowitsch, Hans J

2009-10-30

Dissociative amnesia is a condition usually characterized by severely impaired retrograde memory functioning in the absence of structural brain damage. Recent case studies nevertheless found functional brain changes in patients suffering from autobiographical-episodic memory loss in the cause of dissociative amnesia. Functional changes were demonstrated in both resting state and memory retrieval conditions. In addition, some but not all cases also showed other neuropsychological impairments beyond retrograde memory deficits. However, there is no group study available that examined potential functional brain abnormalities and accompanying neuropsychological deteriorations in larger samples of patients with dissociative retrograde amnesia. We report functional imaging and neuropsychological data acquired in 14 patients with dissociative amnesia following stressful or traumatic events. All patients suffered from autobiographical memory loss. In addition, approximately half of the patients had deficits in anterograde memory and executive functioning. Accompanying functional brain changes were measured by [18F]fluorodeoxyglucose positron emission tomography (FDG-PET). Regional glucose utilization of the patients was compared with that of 19 healthy subjects, matched for age and gender. We found significantly decreased glucose utilization in the right inferolateral prefrontal cortex in the patients. Hypometabolism in this brain region, known to be involved in retrieval of autobiographical memories and self-referential processing, may be a functional brain correlate of dissociative amnesia.

Dissociative excitation of H2, HD, and D2 by electron impact

NASA Technical Reports Server (NTRS)

Carnahan, B. L.; Zipf, E. C.

1977-01-01

Time-of-flight techniques have been used to investigate the electron-impact dissociation of H2, HD, and D2 in order to determine the effect of isotopic mass variation in the target molecule on the dissociative excitation process. At incident electron energies near 100 eV, the time-of-flight spectrum produced from each molecule consists of atoms in the metastable 2s state and in high-lying long-lived Rydberg levels. The individual time-of-flight distributions, kinetic-energy spectra, and relative differential cross sections for these two species resulting from each molecule have been measured. The kinetic-energy spectrum of the Rydberg atoms produced from dissociative excitation of H2 was notably dissimilar in shape from the corresponding distributions produced from HD and D2. Also the 2s and Rydberg production cross sections differed between the three molecules. In the dissociation of the heteronuclear HD molecule, the ratio of fast H(2s) atoms to D(2s) atoms was about 1 to 1, while the same ratio comparing the Rydberg atoms was nearly 2 to 1. These differences indicate the influence of the mass variation on the position of the Franck-Condon region in the production of 2s atoms and on the competition between autoionization and dissociation in the formation of Rydberg fragments.

Ab initio reaction pathways for photodissociation and isomerization of nitromethane on four singlet potential energy surfaces with three roaming paths

NASA Astrophysics Data System (ADS)

Isegawa, Miho; Liu, Fengyi; Maeda, Satoshi; Morokuma, Keiji

2014-06-01

Photodissociation pathways of nitromethane following π → π* electronic excitation are reported. The potential energy surfaces for four lowest singlet states are explored, and structures of many intermediates, dissociation limits, transition states, and minimum energy conical intersections were determined using the automated searching algorism called the global reaction route mapping strategy. Geometries are finally optimized at CASSCF(14e,11o) level and energies are computed at CAS(14o,11e)PT2 level. The calculated preferable pathways and important products qualitatively explain experimental observations. The major photodissociation product CH3 and NO2 (2B2) is formed by direct dissociation from the S1 state. Important pathways involving S1 and S0 states for production of various dissociation products CH3NO + O (1D), CH3O(X2E) + NO (X2Π), CH2NO + OH, and CH2O + HNO, as well as various isomerization pathways have been identified. Three roaming processes also have been identified: the O atom roaming in O dissociation from CH3NO2, the OH radical roaming in OH dissociation from CH2N(O)(OH), and the NO roaming in NO dissociation from CH3ONO.

Ab initio reaction pathways for photodissociation and isomerization of nitromethane on four singlet potential energy surfaces with three roaming paths.

PubMed

Isegawa, Miho; Liu, Fengyi; Maeda, Satoshi; Morokuma, Keiji

2014-06-28

Photodissociation pathways of nitromethane following π → π(*) electronic excitation are reported. The potential energy surfaces for four lowest singlet states are explored, and structures of many intermediates, dissociation limits, transition states, and minimum energy conical intersections were determined using the automated searching algorism called the global reaction route mapping strategy. Geometries are finally optimized at CASSCF(14e,11o) level and energies are computed at CAS(14o,11e)PT2 level. The calculated preferable pathways and important products qualitatively explain experimental observations. The major photodissociation product CH3 and NO2 ((2)B2) is formed by direct dissociation from the S1 state. Important pathways involving S1 and S0 states for production of various dissociation products CH3NO + O ((1)D), CH3O(X(2)E) + NO (X(2)Π), CH2NO + OH, and CH2O + HNO, as well as various isomerization pathways have been identified. Three roaming processes also have been identified: the O atom roaming in O dissociation from CH3NO2, the OH radical roaming in OH dissociation from CH2N(O)(OH), and the NO roaming in NO dissociation from CH3ONO.

Electron induced dissociation in condensed-phase nitromethane I: desorption of ionic fragments.

PubMed

Bazin, Marc; Ptasińska, Sylwia; Bass, Andrew D; Sanche, Léon

2009-03-14

Low energy electron induced dissociation of condensed nitromethane was investigated by measuring the electron stimulated desorption of anions and cations from multilayer films of CH(3)NO(2) and CD(3)NO(2), using a recently constructed, high sensitivity time of flight mass spectrometer. The desorbed yields were measured as a function of incident electron energy in the range between 1 to 20 eV and as function of coverage on Pt and Xe substrates. In anion desorption experiments, the following ions were observed: H(-) (D(-)), O(-), OH(-) (OD(-)), CN(-), NCO(-), NO(2)(-), CHNO(2)(-) (CDNO(2)(-)), CH(2)NO(2)(-) (CD(2)NO(2)(-)). Resonant structure seen in all anion yield functions, is attributed to dissociative electron attachment (DEA), though certain anion signals [e.g., OH(-) (OD(-)) and CH(2)NO(2)(-) (CD(2)NO(2)(-))] are likely the result of reactive scattering by O(-) ions. The dominant desorbed cation signals are CD(3)(+) and NO(+), and the appearance potentials of these species were measured to be 12.2 and 11.5 eV, respectively. The present measurements provide information on how the electron-induced dissociation processes of this proto-typical explosive molecule are modulated by the condensed environment and on how initial dissociation events occurring on a particular molecule, may induce further dissociation.

Laser induced fluorescence spectrum analysis of OH from photo-dissociation of water in gas phase

NASA Astrophysics Data System (ADS)

Li, Guohua; Ye, Jingfeng; Zhang, Zhengrong; Wang, Sheng; Hu, Zhiyun; Zhao, Xinyan

2017-05-01

The OH can be generated from photo-dissociation of water in the gas phase, and the generated OH has served in tagging velocimetry using the time-flight method. The hydroxyl tagging mechanism has the advantages of non-seeding, kindly flow following character, but its application in the reaction region is limited for the fluorescence interference from nascent OH. In this paper, we explored the laser induced fluorescence spectrum of OH both from burning and photodissociation. A photo-dissociation laser induced fluorescence (PD-LIF) system with optical multichannel analysis instrument (OMA) for spectrum analysis was developed. Based on multichannel mechanism, the LIF spectrum of OH from photo-dissociation and burning were acquired simultaneously. The temporal spectrum profiles of dissociation OH both in flame and air were taken by varying the pump-probe delay. The normalized emission spectrum in flame showed a process of rotational relaxation while in air the spectrum was almost not changed. The fluorescence intensity was precisely proportional to the base states population, so we can get certain states that the OH from dissociation was predominant from the fluorescence intensity ratio of OH. This result can be further utilized for hydroxyl tagging velocimetry technology (HTV) which was less affected by burning OH.

Atomic Beam Scattering Methods to Study Overlayer Structures and H-Surface Interaction Relevant to Astrophysics

NASA Astrophysics Data System (ADS)

Lin, Jingsu

In this thesis we present results of experimental methods for studying surface structures of ultra-thin films and describe a new apparatus to study the recombination of atomic hydrogen on well characterized low temperature surface using atomic and molecular beam methods. We have used atomic beam scattering (ABS) to characterize the growth of mercury and lead overlayers on Cu(001) surface. The structures of ordered phases have been identified using ABS and low-energy electron diffraction (LEED). A model to analyze diffraction data from these phases is presented. The new apparatus we are going to describe includes a high performance atomic hydrogen source using radio-frequency (RF) dissociation. The dissociation efficiency can be as high as 90% in the optimized pressure range. An atomic hydrogen beam line has been added to our ultra-high vacuum (UHV) scattering apparatus. We have also designed and constructed a low temperature sample manipulator for experiments at liquid helium temperatures. The manipulator has one degree of freedom of rotation and the capability of heating the sample to 700K and cooling down to 12K. The first sample studied was a single graphite surface. We have used a He beam to characterize the sample surface and to monitor deposition of H on the sample surface in real time. A series of "adsorption curves" have been obtained at different temperature and doses. We found that at temperatures below 16K, both H and H_2 have formed a partial layer on the surface. From adsorption curve, we deduce that the initial sticking coefficient for H is about 0.06 when surface at 16K. When the H beam is interrupted, the He specularly reflected beam recovers partially, indicating that hydrogen atoms desorb, while others remain on the surface. The residual coverage of H is estimated to be about 2% of a monolayer.

Electrically-programmable diffraction grating

DOEpatents

Ricco, Antonio J.; Butler, Michael A.; Sinclair, Michael B.; Senturia, Stephen D.

1998-01-01

An electrically-programmable diffraction grating. The programmable grating includes a substrate having a plurality of electrodes formed thereon and a moveable grating element above each of the electrodes. The grating elements are electrostatically programmable to form a diffraction grating for diffracting an incident beam of light as it is reflected from the upper surfaces of the grating elements. The programmable diffraction grating, formed by a micromachining process, has applications for optical information processing (e.g. optical correlators and computers), for multiplexing and demultiplexing a plurality of light beams of different wavelengths (e.g. for optical fiber communications), and for forming spectrometers (e.g. correlation and scanning spectrometers).

Addition agents effects on hydrocarbon fuels burning

NASA Astrophysics Data System (ADS)

Larionov, V. M.; Mitrofanov, G. A.; Sakhovskii, A. V.

2016-01-01

Literature review on addition agents effects on hydrocarbon fuels burning has been conducted. The impact results in flame pattern and burning velocity change, energy efficiency increase, environmentally harmful NOx and CO emission reduction and damping of self-oscillations in flow. An assumption about water molecules dissociation phenomenon existing in a number of practical applications and being neglected in most explanations for physical- chemical processes taking place in case of injection of water/steam into combustion zone has been noted. The hypothesis about necessity of water dissociation account has been proposed. It can be useful for low temperature combustion process control and NOx emission reduction.

CO2 Dissociation by Low Current Gliding Discharge in the Reverse Vortex Flow

NASA Astrophysics Data System (ADS)

Gutsol, Alexander

2012-10-01

If performed with high energy efficiency, plasma-chemical dissociation of carbon dioxide can be a way of converting and storing energy when there is an excess of electric energy, for example generated by solar elements of wind turbines. CO2 dissociation with efficiency of up to 90% was reported earlier for low pressure microwave discharge in supersonic flow. A new plasma-chemical system uses a low current gliding discharge in the reverse vortex flow of plasma gas. The system is a development of the Gliding Arc in Tornado reactor. The system was used to study dissociation of CO2 in wide ranges of the following experimental parameters: reactor pressure (15-150 kPa), discharge current (50-500 mA), gas flow rate (3-30 liters per minute), and electrode gap length (1-10 cm). Additionally, the effect of thermal energy recuperation on CO2 dissociation efficiency was tested. Plasma chemical efficiency of CO2 dissociation is very low (about 3%) in a short discharge at low pressures (about 15 kPa) when it is defined by electronic excitation. The highest efficiency (above 40%) was reached at pressures 50-70 kPa in a long discharge with thermal energy recuperation. It means that the process is controlled by thermal dissociation with subsequent effective quenching. Plasma chemical efficiency was determined from the data of chromatographic analysis and oscilloscope electric power integration, and also was checked calorimetrically by the thermal balance of the system.

Selfconsistent vibrational and free electron kinetics for CO2 dissociation in cold plasmas

NASA Astrophysics Data System (ADS)

Capitelli, Mario

2016-09-01

The activation of CO2 by cold plasmas is receiving new theoretical interest thanks to two European groups. The Bogaerts group developed a global model for the activation of CO2 trying to reproduce the experimental values for DBD and microwave discharges. The approach of Pietanza et al was devoted to understand the dependence of electron energy distribution function (eedf) of pure CO2 on the presence of concentrations of electronically and vibrationally excited states taken as parameter. To understand the importance of the vibrational excitation in the dissociation process Pietanza et al compared an upper limit to the dissociation process from a pure vibrational mechanism (PVM) with the corresponding electron impact dissociation rate, the prevalence of the two models depending on the reduced electric field and on the choice of the electron molecule cross section database. Improvement of the Pietanza et al model is being considered by coupling the time dependent Boltzmann solver with the non equilibrium vibrational kinetics of asymmetric mode and with simplified plasma chemistry kinetics describing the ionization/recombination process and the excitation-deexcitation of a metastable level at 10.5eV. A new PVM mechanism is also considered. Preliminary results, for both discharge and post discharge conditions, emphasize the action of superelastic collisions involving both vibrationally and electronically excited states in affecting the eedf. The new results can be used to plan a road map for future developments of numerical codes for rationalizing existing experimental values, as well as, for indicating new experimental situations.

Nonequilibrium shock-heated nitrogen flows using a rovibrational state-to-state method

NASA Astrophysics Data System (ADS)

Panesi, M.; Munafò, A.; Magin, T. E.; Jaffe, R. L.

2014-07-01

A rovibrational collisional model is developed to study the internal energy excitation and dissociation processes behind a strong shock wave in a nitrogen flow. The reaction rate coefficients are obtained from the ab initio database of the NASA Ames Research Center. The master equation is coupled with a one-dimensional flow solver to study the nonequilibrium phenomena encountered in the gas during a hyperbolic reentry into Earth's atmosphere. The analysis of the populations of the rovibrational levels demonstrates how rotational and vibrational relaxation proceed at the same rate. This contrasts with the common misconception that translational and rotational relaxation occur concurrently. A significant part of the relaxation process occurs in non-quasi-steady-state conditions. Exchange processes are found to have a significant impact on the relaxation of the gas, while predissociation has a negligible effect. The results obtained by means of the full rovibrational collisional model are used to assess the validity of reduced order models (vibrational collisional and multitemperature) which are based on the same kinetic database. It is found that thermalization and dissociation are drastically overestimated by the reduced order models. The reasons of the failure differ in the two cases. In the vibrational collisional model the overestimation of the dissociation is a consequence of the assumption of equilibrium between the rotational energy and the translational energy. The multitemperature model fails to predict the correct thermochemical relaxation due to the failure of the quasi-steady-state assumption, used to derive the phenomenological rate coefficient for dissociation.

Organic Solar Cells: Understanding the Role of Förster Resonance Energy Transfer

PubMed Central

Feron, Krishna; Belcher, Warwick J.; Fell, Christopher J.; Dastoor, Paul C.

2012-01-01

Organic solar cells have the potential to become a low-cost sustainable energy source. Understanding the photoconversion mechanism is key to the design of efficient organic solar cells. In this review, we discuss the processes involved in the photo-electron conversion mechanism, which may be subdivided into exciton harvesting, exciton transport, exciton dissociation, charge transport and extraction stages. In particular, we focus on the role of energy transfer as described by Förster resonance energy transfer (FRET) theory in the photoconversion mechanism. FRET plays a major role in exciton transport, harvesting and dissociation. The spectral absorption range of organic solar cells may be extended using sensitizers that efficiently transfer absorbed energy to the photoactive materials. The limitations of Förster theory to accurately calculate energy transfer rates are discussed. Energy transfer is the first step of an efficient two-step exciton dissociation process and may also be used to preferentially transport excitons to the heterointerface, where efficient exciton dissociation may occur. However, FRET also competes with charge transfer at the heterointerface turning it in a potential loss mechanism. An energy cascade comprising both energy transfer and charge transfer may aid in separating charges and is briefly discussed. Considering the extent to which the photo-electron conversion efficiency is governed by energy transfer, optimisation of this process offers the prospect of improved organic photovoltaic performance and thus aids in realising the potential of organic solar cells. PMID:23235328

The role of exciton ionization processes in bulk heterojunction organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Zou, Yunlong; Holmes, Russell

2015-03-01

Dissociating photogenerated excitons into their constituent charges is essential for efficient photoconversion in organic semiconductors. Organic photovoltaics cells (OPV) widely adopt a heterojunction architecture where dissociation is facilitated by charge transfer at a donor-acceptor (D-A) interface. Interestingly, recent work on MoOx/C60 Schottky OPVs has demonstrated that excitons in C60 may also undergo bulk-ionization to generate photocurrent, driven by the built-in field at the MoOx/C60 interface. Here, we show that bulk-ionization processes also contribute to the photocurrent in bulk heterojunction (BHJ) OPVs with fullerene-rich compositions. The short-circuit current density (JSC) in a MoOx/C60 Schottky OPVs shows almost no dependence on temperature down to 80 K. This characteristic of bulk-ionization allows the use of temperature-dependent measurements of JSC to distinguish dissociation by bulk-ionization from charge transfer at a D-A interface. For BHJ OPVs constructed using the D-A pairing of boron subphthalocyanine chloride (SubPc)-C60, bulk-ionization is found to contribute >10% of the total photocurrent and >30% of the photocurrent from C60. We further find that fullerene-rich SubPc-C60 BHJ OPVs show a larger open-circuit voltage (VOC) than evenly mixed BHJs due to the presence of bulk-ionization. This talk will examine the dependence of JSC and VOC on the relative fraction of dissociation by charge transfer and bulk-ionization processes.

Photodissociation pathways and lifetimes of protonated peptides and their dimers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aravind, G.; Klaerke, B.; Rajput, J.

2012-01-07

Photodissociation lifetimes and fragment channels of gas-phase, protonated YA{sub n} (n = 1,2) peptides and their dimers were measured with 266 nm photons. The protonated monomers were found to have a fast dissociation channel with an exponential lifetime of {approx}200 ns while the protonated dimers show an additional slow dissociation component with a lifetime of {approx}2 {mu}s. Laser power dependence measurements enabled us to ascribe the fast channel in the monomer and the slow channel in the dimer to a one-photon process, whereas the fast dimer channel is from a two-photon process. The slow (1 photon) dissociation channel in themore » dimer was found to result in cleavage of the H-bonds after energy transfer through these H-bonds. In general, the dissociation of these protonated peptides is non-prompt and the decay time was found to increase with the size of the peptides. Quantum RRKM calculations of the microcanonical rate constants also confirmed a statistical nature of the photodissociation processes in the dipeptide monomers and dimers. The classical RRKM expression gives a rate constant as an analytical function of the number of active vibrational modes in the system, estimated separately on the basis of the equipartition theorem. It demonstrates encouraging results in predicting fragmentation lifetimes of protonated peptides. Finally, we present the first experimental evidence for a photo-induced conversion of tyrosine-containing peptides into monocyclic aromatic hydrocarbon along with a formamide molecule both found in space.« less

IDATEN and G-SITENNO: GUI-assisted software for coherent X-ray diffraction imaging experiments and data analyses at SACLA.

PubMed

Sekiguchi, Yuki; Yamamoto, Masaki; Oroguchi, Tomotaka; Takayama, Yuki; Suzuki, Shigeyuki; Nakasako, Masayoshi

2014-11-01

Using our custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors, cryogenic coherent X-ray diffraction imaging experiments have been undertaken at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility. To efficiently perform experiments and data processing, two software suites with user-friendly graphical user interfaces have been developed. The first is a program suite named IDATEN, which was developed to easily conduct four procedures during experiments: aligning KOTOBUKI-1, loading a flash-cooled sample into the cryogenic goniometer stage inside the vacuum chamber of KOTOBUKI-1, adjusting the sample position with respect to the X-ray beam using a pair of telescopes, and collecting diffraction data by raster scanning the sample with X-ray pulses. Named G-SITENNO, the other suite is an automated version of the original SITENNO suite, which was designed for processing diffraction data. These user-friendly software suites are now indispensable for collecting a large number of diffraction patterns and for processing the diffraction patterns immediately after collecting data within a limited beam time.

A pipeline for comprehensive and automated processing of electron diffraction data in IPLT.

PubMed

Schenk, Andreas D; Philippsen, Ansgar; Engel, Andreas; Walz, Thomas

2013-05-01

Electron crystallography of two-dimensional crystals allows the structural study of membrane proteins in their native environment, the lipid bilayer. Determining the structure of a membrane protein at near-atomic resolution by electron crystallography remains, however, a very labor-intense and time-consuming task. To simplify and accelerate the data processing aspect of electron crystallography, we implemented a pipeline for the processing of electron diffraction data using the Image Processing Library and Toolbox (IPLT), which provides a modular, flexible, integrated, and extendable cross-platform, open-source framework for image processing. The diffraction data processing pipeline is organized as several independent modules implemented in Python. The modules can be accessed either from a graphical user interface or through a command line interface, thus meeting the needs of both novice and expert users. The low-level image processing algorithms are implemented in C++ to achieve optimal processing performance, and their interface is exported to Python using a wrapper. For enhanced performance, the Python processing modules are complemented with a central data managing facility that provides a caching infrastructure. The validity of our data processing algorithms was verified by processing a set of aquaporin-0 diffraction patterns with the IPLT pipeline and comparing the resulting merged data set with that obtained by processing the same diffraction patterns with the classical set of MRC programs. Copyright © 2013 Elsevier Inc. All rights reserved.

A pipeline for comprehensive and automated processing of electron diffraction data in IPLT

PubMed Central

Schenk, Andreas D.; Philippsen, Ansgar; Engel, Andreas; Walz, Thomas

2013-01-01

Electron crystallography of two-dimensional crystals allows the structural study of membrane proteins in their native environment, the lipid bilayer. Determining the structure of a membrane protein at near-atomic resolution by electron crystallography remains, however, a very labor-intense and time-consuming task. To simplify and accelerate the data processing aspect of electron crystallography, we implemented a pipeline for the processing of electron diffraction data using the Image Processing Library & Toolbox (IPLT), which provides a modular, flexible, integrated, and extendable cross-platform, open-source framework for image processing. The diffraction data processing pipeline is organized as several independent modules implemented in Python. The modules can be accessed either from a graphical user interface or through a command line interface, thus meeting the needs of both novice and expert users. The low-level image processing algorithms are implemented in C++ to achieve optimal processing performance, and their interface is exported to Python using a wrapper. For enhanced performance, the Python processing modules are complemented with a central data managing facility that provides a caching infrastructure. The validity of our data processing algorithms was verified by processing a set of aquaporin-0 diffraction patterns with the IPLT pipeline and comparing the resulting merged data set with that obtained by processing the same diffraction patterns with the classical set of MRC programs. PMID:23500887

Phase-retrieval attack free cryptosystem based on cylindrical asymmetric diffraction and double-random phase encoding

NASA Astrophysics Data System (ADS)

Wang, Jun; Li, Xiaowei; Hu, Yuhen; Wang, Qiong-Hua

2018-03-01

A phase-retrieval attack free cryptosystem based on the cylindrical asymmetric diffraction and double-random phase encoding (DRPE) is proposed. The plaintext is abstract as a cylinder, while the observed diffraction and holographic surfaces are concentric cylinders. Therefore, the plaintext can be encrypted through a two-step asymmetric diffraction process with double pseudo random phase masks located on the object surface and the first diffraction surface. After inverse diffraction from a holographic surface to an object surface, the plaintext can be reconstructed using a decryption process. Since the diffraction propagated from the inner cylinder to the outer cylinder is different from that of the reversed direction, the proposed cryptosystem is asymmetric and hence is free of phase-retrieval attack. Numerical simulation results demonstrate the flexibility and effectiveness of the proposed cryptosystem.

On the role of electron-driven processes in planetary atmospheres and comets

NASA Astrophysics Data System (ADS)

Campbell, L.; Brunger, M. J.

2009-11-01

After the presence of ionized layers in the Earth's atmosphere was inferred, it took 50 years to quantitatively understand them. The electron density could not be accounted for until Sir David Bates first suggested (along with Sir Harrie Massey) that the main electron-loss process was dissociative recombination with molecular ions, and he and colleagues then developed a theory to predict those rates of dissociative recombination. However, electron impact processes, particularly excitation, have been considered insignificant in most situations, in both planetary and cometary atmospheres. Here we describe cases where recent calculations have shown that electron impact excitation of molecules is important, suggesting that, just as in the time of Sir David Bates, electron-driven processes remain fundamental to our quantitative understanding of atmospheric and cometary phenomena.

Surface-induced dissociation: a unique tool for studying energetics and kinetics of the gas-phase fragmentation of large ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laskin, Julia

2015-01-01

Surface-induced dissociation (SID) is valuable tool for investigating activation and dissociation of large ions in tandem mass spectrometry. This account summarizes key findings from studies of the energetics and mechanisms of complex ion dissociation, in which SID experiments were combined with Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the experimental data. These studies used time- and collision-energy-resolved SID experiments and SID combined with resonant ejection of selected fragment ions on a specially designed Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Fast ion activation by collision with a surface combined with the long and variable timescale of a FT-ICR MS is perfectlymore » suited for studying the energetics and dynamics of complex ion dissociation in the gas phase. Modeling of time- and collision-energy-resolved SID enables accurate determination of energy and entropy effects in the dissociation process. It has been demonstrated that entropy effects play an important role in determining the dissociation rates of both covalent and non-covalent bonds in large gaseous ions. SID studies have provided important insights on the competition between charge-directed and charge-remote fragmentation in even-electron peptide ions and the role of charge and radical site on the energetics of the dissociation of odd-electron peptide ions. Furthermore, this work examined factors that affect the strength of non-covalent binding, as well as the competition between covalent and non-covalent bond cleavages and between proton and electron transfer in model systems. Finally, SID studies have been used to understand the factors affecting nucleation and growth of clusters in solution and the gas phase.« less

Ionization Cross Sections and Dissociation Channels of DNA Bases by Electron Collisions

NASA Technical Reports Server (NTRS)

Huo, Winifred M.; Dateo, Christopher E.; Fletcher, Graham D.

2004-01-01

Free secondary electrons are the most abundant secondary species in ionizing radiation. Their role in DNA damage, both direct and indirect, is an active area of research. While indirect damage by free radicals, particularly by the hydroxyl radical generated by electron collision with water. is relatively well studied, damage by direct electron collision with DNA is less well understood. Only recently Boudaiffa et al. demonstrated that electrons at energies well below ionization thresholds can induce substantial yields of single- and double-strand breaks in DNA by a resonant, dissociative attachment process. This study attracted renewed interest in electron collisions with DNA, especially in the low energy region. At higher energies ionization becomes important. While Monte Carlo track simulations of radiation damage always include ionization, the probability of dissociative ionization, i.e., simultaneous ionization and dissociation, is ignored. Just like dissociative attachment, dissociative ionization may be an important contributor to double-strand breaks since the radicals and ions produced by dissociative ionization, located in the vicinity of the DNA coil, can readily interact with other parts of the DNA. Using the improved binary-encounter dipole (iBED) formulation, we calculated the ionization cross sections of the four DNA bases, adenine, cytosine, guanine, and thymine, by electrons at energies from threshold to 1 KeV. The present calculation gives cross sections approximately 20% lower than the results by Bemhardt and Paretzke using the Deutsch-Mark and Binary-Encounter-Bethe (BEB) formalisms. The difference is most likely due to the lack of a shielding term in the dipole potential used in the Deutsch-Mark and BEB formalisms. The dissociation channels of ionization for the bases are currently being studied.

Process dissociation of familiarity and recollection in children: response deadline affects recollection but not familiarity.

PubMed

Koenig, Laura; Wimmer, Marina C; Hollins, Timothy J

2015-03-01

According to dual-process theories, recollection (slow and associated with contextual details) and familiarity (fast and automatic) are two independent processes underlying recognition memory. An adapted version of the process dissociation paradigm was used to measure recognition memory in 5-, 7-, and 11-year-olds and adults. In Experiment 1, it was found that 5-year-olds already recollect details of items (i.e., number). Recollection increased particularly between 5 and 7 years. Familiarity differed between 5 years and adulthood. In Experiment 2, under limited response time during retrieval, recollection was eliminated in 5-year-olds and reduced across all ages, whereas familiarity was left unaffected. Together, these findings are consistent with dual-process theories of recognition memory and provide support for two processes underlying recognition memory from a developmental perspective. Copyright © 2014 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2018-06-01

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

Dissociative electron attachment and vibrational excitation of CF{sub 3}Cl: Effect of two vibrational modes revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tarana, Michal; JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440; Houfek, Karel

We present a study of dissociative electron attachment and vibrational excitation processes in electron collisions with the CF{sub 3}Cl molecule. The calculations are based on the two-dimensional nuclear dynamics including the C-Cl symmetric stretch coordinate and the CF{sub 3} symmetric deformation (umbrella) coordinate. The complex potential energy surfaces are calculated using the ab initio R-matrix method. The results for dissociative attachment and vibrational excitation of the umbrella mode agree quite well with experiment whereas the cross section for excitation of the C-Cl symmetric stretch vibrations is about a factor-of-three too low in comparison with experimental data.

Dissociative and double photoionization of CO2 from threshold to 90 A

NASA Technical Reports Server (NTRS)

Masuoka, T.; Samson, J. A. R.

1979-01-01

The molecular photoionization, dissociative photoionization and double photoionization cross sections for CO2 were measured from their onsets down to 90 A by using various combinations of mass spectrometers (a coincidence time-of-flight mass spectrometer and a magnetic mass spectrometer) and light sources (synchrotron radiation, and glow and spark discharge). It is concluded that the one broad peak and the three shoulders in the total adsorption cross section curve between 640 and 90 A are caused completely by dissociative ionization processes. Several peaks observed in the cross section curve for the total fragmentation CO(+)3, O(+) and C(+) are compared with those in the photoelectron spectrum reported for CO2.

Effects of chemical equilibrium on turbine engine performance for various fuels and combustor temperatures

NASA Technical Reports Server (NTRS)

Tran, Donald H.; Snyder, Christopher A.

1992-01-01

A study was performed to quantify the differences in turbine engine performance with and without the chemical dissociation effects for various fuel types over a range of combustor temperatures. Both turbojet and turbofan engines were studied with hydrocarbon fuels and cryogenic, nonhydrocarbon fuels. Results of the study indicate that accuracy of engine performance decreases when nonhydrocarbon fuels are used, especially at high temperatures where chemical dissociation becomes more significant. For instance, the deviation in net thrust for liquid hydrogen fuel can become as high as 20 percent at 4160 R. This study reveals that computer central processing unit (CPU) time increases significantly when dissociation effects are included in the cycle analysis.

Advanced MRI in Acute Military TBI

DTIC Science & Technology

2013-09-01

state up to 24 h, post-traumatic amnesia up to 24 h and the absence of abnormalities in computed tomography or conventional magnetic resonance imaging...Mukherjee, P., Ghajar, J., Johnson, C.E., Kolster, R., Lee, H., Suh, M., Zimmerman, R.D., Manley, G.T., McCandliss, B.D., 2008. Structural dissociation ...Greicius, M.D., 2007. Dissociable intrinsic connectivity networks for salience process- ing and executive control. J. Neurosci. 27, 2349–2356

REACTOR NOZZLE ASSEMBLY

DOEpatents

Capuder, F.C.; Dearwater, J.R.

1959-02-10

An improved nozzle assembly useful in a process for the direct reduction of uranium hexafluoride to uranium tetrafluoride by means of dissociated ammonia in a heated reaction vessel is descrlbed. The nozzle design provides for intimate mixing of the two reactants and at the same time furnishes a layer of dissociated ammonia adjacent to the interior wall of the reaction vessel, thus preventing build-up of the reaction product on the vessel wall.

Laser Photochemistry.

DTIC Science & Technology

1981-07-01

continuum and is the important parameter for determining the dissociation yield (Grant et al., 1978). The phenomenon of infrared MPE and MPD seems well under...incoherent absorption processes in MPE and MPD? What is the magnitude of the absorption cross section and how does it change with molecular parameters ...iv) What is the dynamics of the dissociation event and what are the parameters that determine the rate of unimolecular decom- position? (v) How can

Understanding Phonological Memory Deficits in Boys with Attention-Deficit/Hyperactivity Disorder (ADHD): Dissociation of Short-Term Storage and Articulatory Rehearsal Processes

ERIC Educational Resources Information Center

Bolden, Jennifer; Rapport, Mark D.; Raiker, Joseph S.; Sarver, Dustin E.; Kofler, Michael J.

2012-01-01

The current study dissociated and examined the two primary components of the phonological working memory subsystem--the short-term store and articulatory rehearsal mechanism--in boys with ADHD (n = 18) relative to typically developing boys (n = 15). Word lists of increasing length (2, 4, and 6 words per trial) were presented to and recalled by…

Words, Hemispheres, and Dissociable Subsystems: The Effects of Exposure Duration, Case Alternation, Priming, and Continuity of Form on Word Recognition in the Left and Right Visual Fields

ERIC Educational Resources Information Center

Ellis, Andrew W.; Ansorge, Lydia; Lavidor, Michal

2007-01-01

Three experiments explore aspects of the dissociable neural subsystems theory of hemispheric specialisation proposed by Marsolek and colleagues, and in particular a study by [Deason, R. G., & Marsolek, C. J. (2005). A critical boundary to the left-hemisphere advantage in word processing. "Brain and Language," 92, 251-261]. Experiment 1A showed…

Associations of emotional arousal, dissociation and symptom severity with operant conditioning in borderline personality disorder.

PubMed

Paret, Christian; Hoesterey, Steffen; Kleindienst, Nikolaus; Schmahl, Christian

2016-10-30

Those with borderline personality disorder (BPD) display altered evaluations regarding reward and punishment compared to others. The processing of rewards is basal for operant conditioning. However, studies addressing operant conditioning in BPD patients are rare. In the current study, an operant conditioning task combining learning acquisition and reversal was used. BPD patients and matched healthy controls (HCs) were exposed to aversive and neutral stimuli to assess the influence of emotion on learning. Picture content, dissociation, aversive tension and symptom severity were rated. Error rates were measured. Results showed no group interactions between aversive versus neutral scenes. The higher emotional arousal, dissociation and tension, the worse the acquisition, but not reversal, scores were for BPD patients. Scores from the Borderline Symptom List were associated with more errors in the reversal, but not the acquisition phase. The results are preliminary evidence for impaired acquisition learning due to increased emotional arousal, dissociation and tension in BPD patients. A failure to process punishment in the reversal phase was associated with symptom severity and may be related to neuropsychological dysfunctioning involving the ventromedial prefrontal cortex. Conclusions are limited due to the correlational study design and the small sample size. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Catalytic water dissociation by greigite Fe3S4 surfaces: density functional theory study

PubMed Central

Roldan, A.; de Leeuw, N. H.

2016-01-01

The iron sulfide mineral greigite, Fe3S4, has shown promising capability as a hydrogenating catalyst, in particular in the reduction of carbon dioxide to produce small organic molecules under mild conditions. We employed density functional theory calculations to investigate the {001},{011} and {111} surfaces of this iron thiospinel material, as well as the production of hydrogen ad-atoms from the dissociation of water molecules on the surfaces. We systematically analysed the adsorption geometries and the electronic structure of both bare and hydroxylated surfaces. The sulfide surfaces presented a higher flexibility than the isomorphic oxide magnetite, Fe3O4, allowing perpendicular movement of the cations above or below the top atomic sulfur layer. We considered both molecular and dissociative water adsorption processes, and have shown that molecular adsorption is the predominant state on these surfaces from both a thermodynamic and kinetic point of view. We considered a second molecule of water which stabilizes the system mainly by H-bonds, although the dissociation process remains thermodynamically unfavourable. We noted, however, synergistic adsorption effects on the Fe3S4{001} owing to the presence of hydroxyl groups. We concluded that, in contrast to Fe3O4, molecular adsorption of water is clearly preferred on greigite surfaces. PMID:27274698

Electrically-programmable diffraction grating

DOEpatents

Ricco, A.J.; Butler, M.A.; Sinclair, M.B.; Senturia, S.D.

1998-05-26

An electrically-programmable diffraction grating is disclosed. The programmable grating includes a substrate having a plurality of electrodes formed thereon and a moveable grating element above each of the electrodes. The grating elements are electrostatically programmable to form a diffraction grating for diffracting an incident beam of light as it is reflected from the upper surfaces of the grating elements. The programmable diffraction grating, formed by a micromachining process, has applications for optical information processing (e.g. optical correlators and computers), for multiplexing and demultiplexing a plurality of light beams of different wavelengths (e.g. for optical fiber communications), and for forming spectrometers (e.g. correlation and scanning spectrometers). 14 figs.

Demonstrating the effects of phonological similarity and frequency on item and order memory in Down syndrome using process dissociation.

PubMed

Smith, Elizabeth; Jarrold, Christopher

2014-12-01

It is important to distinguish between memory for item information and memory for order information when considering the nature of verbal short-term memory (vSTM) performance. Although other researchers have attempted to make this distinction between item and order memory in children, none has done so using process dissociation. This study shows that such an approach can be particularly useful and informative. Individuals with Down syndrome (DS) tend to experience a vSTM deficit. These two experiments explored whether phonological similarity (Experiment 1) and item frequency (Experiment 2) affected vSTM for item and order information in a group of individuals with DS compared with typically developing (TD) vocabulary-matched children. Process dissociation was used to obtain measures of item and order memory via Nairne and Kelley's procedure (Journal of Memory and Language, 50 (2004) 113-133). Those with DS were poorer than the matched TD group for recall of both item and order information. However, in both populations, phonologically similar items reduced order memory but enhanced item memory, whereas high-frequency items resulted in improvements in both item and order memory-effects that are in line with previous research in the adult literature. These results indicate that, despite poorer vSTM performance in DS, individuals experience phonological coding of verbal input and a contribution of long-term memory knowledge to recall. These findings inform routes for interventions for those with DS, highlighting the need to enhance both item and order memory. Moreover, this work demonstrates that process dissociation is applicable and informative for studying special populations and children. Copyright © 2014 Elsevier Inc. All rights reserved.

Dissociation energies of Ag–RG (RG = Ar, Kr, Xe) and AgO molecules from velocity map imaging studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, Graham A.; Gentleman, Alexander S.; Iskra, Andreas

2015-09-28

The near ultraviolet photodissociation dynamics of silver atom—rare gas dimers have been studied by velocity map imaging. Ag–RG (RG = Ar, Kr, Xe) species generated by laser ablation are excited in the region of the C ({sup 2}Σ{sup +})←X ({sup 2}Σ{sup +}) continuum leading to direct, near-threshold dissociation generating Ag* ({sup 2}P{sub 3/2}) + RG ({sup 1}S{sub 0}) products. Images recorded at excitation wavelengths throughout the C ({sup 2}Σ{sup +})←X ({sup 2}Σ{sup +}) continuum, coupled with known atomic energy levels, permit determination of the ground X ({sup 2}Σ{sup +}) state dissociation energies of 85.9 ± 23.4 cm{sup −1} (Ag–Ar), 149.3 ±more » 22.4 cm{sup −1} (Ag–Kr), and 256.3 ± 16.0 cm{sup −1} (Ag–Xe). Three additional photolysis processes, each yielding Ag atom photoproducts, are observed in the same spectral region. Two of these are markedly enhanced in intensity upon seeding the molecular beam with nitrous oxide, and are assigned to photodissociation of AgO at the two-photon level. These features yield an improved ground state dissociation energy for AgO of 15 965 ± 81 cm{sup −1}, which is in good agreement with high level calculations. The third process results in Ag atom fragments whose kinetic energy shows anomalously weak photon energy dependence and is assigned tentatively to dissociative ionization of the silver dimer Ag{sub 2}.« less

The photodissociation dynamics of the ethyl radical, C2H5, investigated by velocity map imaging.

PubMed

Steinbauer, Michael; Giegerich, Jens; Fischer, Kathrin H; Fischer, Ingo

2012-07-07

The photodissociation dynamics of the ethyl radical C(2)H(5) has been investigated by velocity map imaging. Ethyl was produced by flash pyrolysis from n-propyl nitrite and excited to the à (2)A(') (3s) Rydberg state around 250 nm. The energetically most favorable reaction channel in this wavelength region is dissociation to C(2)H(4) (ethene) + H. The H-atom dissociation products were ionized in a [1+1(')] process via the 1s-2p transition. The observed translational energy distribution is bimodal: A contribution of slow H-atoms with an isotropic angular distribution peaks at low translational energies. An expectation value for the fraction of excess energy released into translation of = 0.19 is derived from the data, typical for statistical dissociation reactions. In addition, a fast H-atom channel is observed, peaking around 1.8 eV. The latter shows an anisotropic distribution with β = 0.45. It originates from a direct dissociation process within less than a rotational period. Time-delay scans with varying extraction voltages indicate the presence of two rates for the formation of H-atoms. One rate with a sub-nanosecond time constant is associated with H-atoms with large translational energy; a second one with a time constant on the order of 100 ns is associated with H-atoms formed with low translational energy. The data confirm and extend those from previous experiments and remove some inconsistencies. Possible mechanisms for the dissociation are discussed in light of the new results as well as previous ones.

Dissociation free-energy profiles of specific and nonspecific DNA-protein complexes.

PubMed

Yonetani, Yoshiteru; Kono, Hidetoshi

2013-06-27

DNA-binding proteins recognize DNA sequences with at least two different binding modes: specific and nonspecific. Experimental structures of such complexes provide us a static view of the bindings. However, it is difficult to reveal further mechanisms of their target-site search and recognition only from static information because the transition process between the bound and unbound states is not clarified by static information. What is the difference between specific and nonspecific bindings? Here we performed adaptive biasing force molecular dynamics simulations with the specific and nonspecific structures of DNA-Lac repressor complexes to investigate the dissociation process. The resultant free-energy profiles showed that the specific complex has a sharp, deep well consistent with tight binding, whereas the nonspecific complex has a broad, shallow well consistent with loose binding. The difference in the well depth, ~5 kcal/mol, was in fair agreement with the experimentally obtained value and was found to mainly come from the protein conformational difference, particularly in the C-terminal tail. Also, the free-energy profiles were found to be correlated with changes in the number of protein-DNA contacts and that of surface water molecules. The derived protein spatial distributions around the DNA indicate that any large dissociation occurs rarely, regardless of the specific and nonspecific sites. Comparison of the free-energy barrier for sliding [~8.7 kcal/mol; Furini J. Phys. Chem. B 2010, 114, 2238] and that for dissociation (at least ~16 kcal/mol) calculated in this study suggests that sliding is much preferred to dissociation.

Effects of Charge State on Fragmentation Pathways, Dynamics, and Activation Energies of Ubiquitin Ions Measured by Blackbody Infrared Radiative Dissociation

PubMed Central

Jockusch, Rebecca A.; Schnier, Paul D.; Price, William D.; Strittmatter, Eric. F.; Demirev, Plamen A.; Williams*, Evan R.

2005-01-01

Blackbody infrared radiative dissociation spectra of the (M + 5H)5+ through (M + 11H)11+ ions of the protein ubiquitin (8.6 kDa) formed by electrospray ionization were measured in a Fourier-transform mass spectrometer. The 5+ ion dissociates exclusively by loss of water and/or ammonia, whereas the 11+ charge state dissociates only by formation of complementary y and b ions. These two processes are competitive for intermediate charge state ions, with the formation of y and b ions increasingly favored for the higher charge states. The y and b ions are formed by cleavage of the backbone amide bond on the C-terminal side of acidic residues exclusively, with cleavage adjacent to aspartic acid favored. Thermal unimolecular dissociation rate constants for the dissociation of each of these charge states were measured. From the temperature dependence of these rates, Arrhenius activation parameters in the rapid energy exchange limit are obtained. The activation energies (Ea) and preexponential factors (A) for the 5+, 8+, and 9+ ions are 1.2 eV and 1012 s−1, respectively. These values for the 6+ and 7+ ions are 0.9–1.0 eV and 109 s−1, and those for the 10+ and 11+ ions are 1.6 eV and 1016–1017 s−1. Thus, with the exception of the 5+ ion, the higher charge states of ubiquitin have larger dissociation activation energies than the lower charge states. The different A factors observed for production of y and b ions from different precursor charge states indicate that they are formed by different mechanisms, ranging from relatively complex rearrangements to direct bond cleavages. These results clearly demonstrate that the relative dissociation rates of large biomolecule ions by themselves are not necessarily a reliable indicator of their relative dissociation energies, even when similar fragment ions are formed. PMID:9075403

Effects of charge state on fragmentation pathways, dynamics, and activation energies of ubiquitin ions measured by blackbody infrared radiative dissociation.

PubMed

Jockusch, R A; Schnier, P D; Price, W D; Strittmatter, E F; Demirev, P A; Williams, E R

1997-03-15

Blackbody infrared radiative dissociation spectra of the (M + 5H)5+ through (M + 11H)11+ ions of the protein ubiquitin (8.6 kDa) formed by electrospray ionization were measured in a Fourier-transform mass spectrometer. The 5+ ion dissociates exclusively by loss of water and/or ammonia, whereas the 11+ charge state dissociates only by formation of complementary y and b ions. These two processes are competitive for intermediate charge state ions, with the formation of y and b ions increasingly favored for the higher charge states. The y and b ions are formed by cleavage of the backbone amide bond on the C-terminal side of acidic residues exclusively, with cleavage adjacent to aspartic acid favored. Thermal unimolecular dissociation rate constants for the dissociation of each of these charge states were measured. From the temperature dependence of these rates, Arrhenius activation parameters in the rapid energy exchange limit are obtained. The activation energies (Ea) and preexponential factors (A) for the 5+, 8+, and 9+ ions are 1.2 eV and 10(12) s-1, respectively. These values for the 6+ and 7+ ions are 0.9-1.0 eV and 10(9) s-1, and those for the 10+ and 11+ ions are 1.6 eV and 10(16)-10(17) s-1. Thus, with the exception of the 5+ ion, the higher charge states of ubiquitin have larger dissociation activation energies than the lower charge states. The different A factors observed for production of y and b ions from different precursor charge states indicate that they are formed by different mechanisms, ranging from relatively complex rearrangements to direct bond cleavages. These results clearly demonstrate that the relative dissociation rates of large biomolecule ions by themselves are not necessarily a reliable indicator of their relative dissociation energies, even when similar fragment ions are formed.

Far-infrared image restoration analysis of the protostellar cluster in S140

NASA Technical Reports Server (NTRS)

Lester, D. F.; Harvey, P. M.; Joy, M.; Ellis, H. B., Jr.

1986-01-01

Image restoration techniques are applied to one-dimensional scans at 50 and 100 microns of the protostellar cluster in S140. These measurements resolve the surrounding nebula clearly, and Fourier methods are used to match the effective beam profiles at these wavelengths. This allows the radial distribution of temperature and dust column density to be derived at a diffraction limited spatial resolution of 23 arcsec (0.1 pc). Evidence for heating of the S140 molecular cloud by a nearby ionization front is established, and the dissociation of molecules inside the ionization front is spatially well correlated with the heating of the dust. The far-infrared spectral distribution of the three near-infrared sources within 10 arcsesc of the cluster center is presented.

Transition from overlayer growth to alloying growth of Ga on Si(111)-alpha-(sqrt[3]xsqrt[3])-Au.

PubMed

Yamanaka, T; Ino, S

2002-11-04

Atomic depth distribution and growth modes of Ga on an Si(111)-alpha-(sqrt[3]xsqrt[3])-Au surface at room temperature were studied after each monolayer deposition of Ga via reflection high-energy electron diffraction and characteristic x-ray spectroscopy measurements as functions of glancing angle theta(g) of the incident electron beam. One monolayer of Ga grew on the Au layer, and the sqrt[3]xsqrt[3] periodicity was conserved below the Ga overlayer. Above a critical Ga coverage of about one monolayer, this growth mode drastically changed; i.e., Au atoms dissociated from the sqrt[3]xsqrt[3] structure and Ga grew into islands of Ga-Au alloy.

Effect of Cobalt Particle Size on Acetone Steam Reforming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Junming; Zhang, He; Yu, Ning

2015-06-11

Carbon-supported cobalt nanoparticles with different particle sizes were synthesized and characterized by complementary characterization techniques such as X-ray diffraction, N-2 sorption, acetone temperature-programmed desorption, transmission electron microscopy, and CO chemisorption. Using acetone steam reforming reaction as a probe reaction, we revealed a volcano-shape curve of the intrinsic activity (turnover frequency of acetone) and the CO2 selectivity as a function of the cobalt particle size with the highest activity and selectivity observed at a particle size of approximately 12.8nm. Our results indicate that the overall performance of acetone steam reforming is related to a combination of particle-size-dependent acetone decomposition, water dissociation,more » and the oxidation state of the cobalt nanoparticles.« less

Device and method for separating oxygen isotopes

DOEpatents

Rockwood, Stephen D.; Sander, Robert K.

1984-01-01

A device and method for separating oxygen isotopes with an ArF laser which produces coherent radiation at approximately 193 nm. The output of the ArF laser is filtered in natural air and applied to an irradiation cell where it preferentially photodissociates molecules of oxygen gas containing .sup.17 O or .sup.18 O oxygen nuclides. A scavenger such as O.sub.2, CO or ethylene is used to collect the preferentially dissociated oxygen atoms and recycled to produce isotopically enriched molecular oxygen gas. Other embodiments utilize an ArF laser which is narrowly tuned with a prism or diffraction grating to preferentially photodissociate desired isotopes. Similarly, desired mixtures of isotopic gas can be used as a filter to photodissociate enriched preselected isotopes of oxygen.

Automatic and controlled components of judgment and decision making.

PubMed

Ferreira, Mario B; Garcia-Marques, Leonel; Sherman, Steven J; Sherman, Jeffrey W

2006-11-01

The categorization of inductive reasoning into largely automatic processes (heuristic reasoning) and controlled analytical processes (rule-based reasoning) put forward by dual-process approaches of judgment under uncertainty (e.g., K. E. Stanovich & R. F. West, 2000) has been primarily a matter of assumption with a scarcity of direct empirical findings supporting it. The present authors use the process dissociation procedure (L. L. Jacoby, 1991) to provide convergent evidence validating a dual-process perspective to judgment under uncertainty based on the independent contributions of heuristic and rule-based reasoning. Process dissociations based on experimental manipulation of variables were derived from the most relevant theoretical properties typically used to contrast the two forms of reasoning. These include processing goals (Experiment 1), cognitive resources (Experiment 2), priming (Experiment 3), and formal training (Experiment 4); the results consistently support the author's perspective. They conclude that judgment under uncertainty is neither an automatic nor a controlled process but that it reflects both processes, with each making independent contributions.

Eye Tracking and Pupillometry are Indicators of Dissociable Latent Decision Processes

PubMed Central

Cavanagh, James F.; Wiecki, Thomas V.; Kochar, Angad; Frank, Michael J.

2014-01-01

Can you predict what someone is going to do just by watching them? This is certainly difficult: it would require a clear mapping between observable indicators and unobservable cognitive states. In this report we demonstrate how this is possible by monitoring eye gaze and pupil dilation, which predict dissociable biases during decision making. We quantified decision making using the Drift Diffusion Model (DDM), which provides an algorithmic account of how evidence accumulation and response caution contribute to decisions through separate latent parameters of drift rate and decision threshold, respectively. We used a hierarchical Bayesian estimation approach to assess the single trial influence of observable physiological signals on these latent DDM parameters. Increased eye gaze dwell time specifically predicted an increased drift rate toward the fixated option, irrespective of the value of the option. In contrast, greater pupil dilation specifically predicted an increase in decision threshold during difficult decisions. These findings suggest that eye tracking and pupillometry reflect the operations of dissociated latent decision processes. PMID:24548281

Energetics and dynamics through time-resolved measurements in mass spectrometry

NASA Astrophysics Data System (ADS)

Lifshitz, Chava

Results of recent work on time-resolved photoionization and electron ionization mass spectrometry carried out in Jerusalem are reviewed. Time-resolved photoionization mass spectrometry in the vacuum ultraviolet is applied to polycyclic aromatic hydrocarbons, for example naphthalene, pyrene and fluoranthene as well as to some bromo derivatives (bromonaphthalene and bromoanthracene). Time-resolved photoionization efficiency curves are modelled by Rice-Ramsperger-Kassel-Marcus QET rate-energy k ( E ) dependences of the unimolecular dissociative processes and by the rate process infrared radiative relaxation k . Experimental results are augmented by time-resolved photorad dissociation data for the same species, whenever available. Kinetic shifts, conventional and intrinsic (due to competition between dissociative and radiative decay), are evaluated. Activation parameters (activation energies and entropies) are deduced. Thermochemical information is obtained including bond energies and ionic heats of formation. Fullerenes, notably C , are studied by time-resolved electron ionization and a large intrinsic shift, due to competition with black-bodylike radiative decay in the visible is discussed.

Reactive molecular dynamics simulation of solid nitromethane impact on (010) surfaces induced and nonimpact thermal decomposition.

PubMed

Guo, Feng; Cheng, Xin-lu; Zhang, Hong

2012-04-12

Which is the first step in the decomposition process of nitromethane is a controversial issue, proton dissociation or C-N bond scission. We applied reactive force field (ReaxFF) molecular dynamics to probe the initial decomposition mechanisms of nitromethane. By comparing the impact on (010) surfaces and without impact (only heating) for nitromethane simulations, we found that proton dissociation is the first step of the pyrolysis of nitromethane, and the C-N bond decomposes in the same time scale as in impact simulations, but in the nonimpact simulation, C-N bond dissociation takes place at a later time. At the end of these simulations, a large number of clusters are formed. By analyzing the trajectories, we discussed the role of the hydrogen bond in the initial process of nitromethane decompositions, the intermediates observed in the early time of the simulations, and the formation of clusters that consisted of C-N-C-N chain/ring structures.

Deconstructing the brain’s moral network: dissociable functionality between the temporoparietal junction and ventro-medial prefrontal cortex

PubMed Central

Mobbs, Dean; Dalgleish, Tim

2014-01-01

Research has illustrated that the brain regions implicated in moral cognition comprise a robust and broadly distributed network. However, understanding how these brain regions interact and give rise to the complex interplay of cognitive processes underpinning human moral cognition is still in its infancy. We used functional magnetic resonance imaging to examine patterns of activation for ‘difficult’ and ‘easy’ moral decisions relative to matched non-moral comparators. This revealed an activation pattern consistent with a relative functional double dissociation between the temporoparietal junction (TPJ) and ventro-medial prefrontal cortex (vmPFC). Difficult moral decisions activated bilateral TPJ and deactivated the vmPFC and OFC. In contrast, easy moral decisions revealed patterns of activation in the vmPFC and deactivation in bilateral TPJ and dorsolateral PFC. Together these results suggest that moral cognition is a dynamic process implemented by a distributed network that involves interacting, yet functionally dissociable networks. PMID:23322890

Dissociation and Convergence of the Dorsal and Ventral Visual Streams in the Human Prefrontal Cortex

PubMed Central

Takahashi, Emi; Ohki, Kenichi; Kim, Dae-Shik

2012-01-01

Visual information is largely processed through two pathways in the primate brain: an object pathway from the primary visual cortex to the temporal cortex (ventral stream) and a spatial pathway to the parietal cortex (dorsal stream). Whether and to what extent dissociation exists in the human prefrontal cortex (PFC) has long been debated. We examined anatomical connections from functionally defined areas in the temporal and parietal cortices to the PFC, using noninvasive functional and diffusion-weighted magnetic resonance imaging. The right inferior frontal gyrus (IFG) received converging input from both streams, while the right superior frontal gyrus received input only from the dorsal stream. Interstream functional connectivity to the IFG was dynamically recruited only when both object and spatial information were processed. These results suggest that the human PFC receives dissociated and converging visual pathways, and that the right IFG region serves as an integrator of the two types of information. PMID:23063444

Coherent control at its most fundamental: carrier-envelope-phase-dependent electron localization in photodissociation of a H2(+) molecular ion beam target.

PubMed

Rathje, T; Sayler, A M; Zeng, S; Wustelt, P; Figger, H; Esry, B D; Paulus, G G

2013-08-30

Measurements and calculations of the absolute carrier-envelope-phase (CEP) effects in the photodissociation of the simplest molecule, H2(+), with a 4.5-fs Ti:sapphire laser pulse at intensities up to (4±2)×10(14)  W/cm2 are presented. Localization of the electron with respect to the two nuclei (during the dissociation process) is controlled via the CEP of the ultrashort laser pulses. In contrast to previous CEP-dependent experiments with neutral molecules, the dissociation of the molecular ions is not preceded by a photoionization process, which strongly influences the CEP dependence. Kinematically complete data are obtained by time- and position-resolved coincidence detection. The phase dependence is determined by a single-shot phase measurement correlated to the detection of the dissociation fragments. The experimental results show quantitative agreement with ab initio 3D time-dependent Schrödinger equation calculations that include nuclear vibration and rotation.

Phase stability of iron germanate, FeGeO3, to 127 GPa

NASA Astrophysics Data System (ADS)

Dutta, R.; Tracy, S. J.; Stan, C. V.; Prakapenka, V. B.; Cava, R. J.; Duffy, T. S.

2018-04-01

The high-pressure behavior of germanates is of interest as these compounds serve as analogs for silicates of the deep Earth. Current theoretical and experimental studies of iron germanate, FeGeO3, are limited. Here, we have examined the behavior of FeGeO3 to 127 GPa using the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. Upon compression at room temperature, the ambient-pressure clinopyroxene phase transforms to a disordered triclinic phase [FeGeO3 (II)] at 18 GPa in agreement with earlier studies. An additional phase transition to FeGeO3 (III) occurs above 54 GPa at room temperature. Laser-heating experiments ( 1200-2200 K) were conducted at three pressures (33, 54, and 123 GPa) chosen to cover the stability regions of different GeO2 polymorphs. In all cases, we observe that FeGeO3 dissociates into GeO2 + FeO at high pressure and temperature conditions. Neither the perovskite nor the post-perovskite phase was observed up to 127 GPa at ambient or high temperatures. The results are consistent with the behavior of FeSiO3, which also dissociates into a mixture of the oxides (FeO + SiO2) at least up to 149 GPa.

Celecoxib:Nicotinamide Dissociation: Using Excipients to Capture the Cocrystal's Potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Remenar,J.; Peterson, M.; Stephens, P.

2007-01-01

The cocrystal of celecoxib and nicotinamide (Cel:Nic) was crystallized from chloroform in a 1:1 ratio, and the structure has been solved from powder X-ray diffraction data. The dissolution and solubility of Cel:Nic are medium dependent and can be attributed to differences in conversion of Cel:Nic to celecoxib polymorphs I and III (Cel-I and Cel-III). The presence of low concentrations of surfactants facilitates the rapid conversion of neat Cel:Nic to large aggregates of Cel-III that dissolve more slowly than commercial Cel-III into 1% SDS solution. In contrast, combinations of Cel:Nic with both 1-10% solid SDS and PVP wet rapidly and convertmore » to a mixture of amorphous celecoxib and a micron-sized crystalline celecoxib form IV (Cel-IV), which has recently been shown to be up to 4-fold more bioavailable than marketed Cel-III. More than 90% of the suspended material dissolves within 2 min at 37 C when transferred to 1% SDS solution. This example highlights the importance of exploring the form conversion of cocrystals in aqueous media prior to pharmacokinetic studies, and illustrates the potential of simple formulations to overcome the limitations caused by rapid dissociation of cocrystals and recrystallization of poorly soluble forms in aqueous media.« less

CCl 4 chemistry on the reduced selvedge of a α-Fe 2O 3(0 0 0 1) surface: a scanning tunneling microscopy study

NASA Astrophysics Data System (ADS)

Rim, Kwang Taeg; Fitts, Jeffrey P.; Müller, Thomas; Adib, Kaveh; Camillone, Nicholas; Osgood, Richard M.; Joyce, S. A.; Flynn, George W.

2003-09-01

Scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) were used to study the degradation of CCl 4 on the reduced selvedge of a natural single crystal α-Fe 2O 3(0 0 0 1) surface in ultrahigh vacuum. Before exposure to CCl 4, STM images indicate that approximately 85% of the reduced surface exhibits a Fe 3O 4(1 1 1) 2 × 2 termination, while the remaining 15% is terminated by 1 × 1 and superstructure phases. Images obtained after room temperature dosing with CCl 4 and subsequent flashing to 600 K reveal that chlorine atoms are adsorbed only on surface regions with the Fe 3O 4(1 1 1) 2 × 2 termination, not on 1 × 1 and superstructure regions. Chlorine atoms from dissociative adsorption of CCl 4 are observed to occupy two distinct positions located atop lattice protrusions and in threefold oxygen vacancy sites. However, in companion chemical labeling experiments, chlorine atoms provided by room temperature, dissociative Cl 2 adsorption on this surface are found to occupy sites atop lattice protrusions exclusively. The clear dissimilarity in STM feature shape and brightness at the two distinct chlorine adsorption sites arising from CCl 4 dissociation as well as the results of the Cl 2 chemical labeling experiments are best explained via reactions on a Fe 3O 4(1 1 1) 2 × 2 selvedge terminated by a 1/4 monolayer of tetrahedrally coordinated iron atoms. On this surface, adsorption atop an iron atom occurs for both the CCl 4 and Cl 2 dissociative reactions. A second adsorption site, assigned as binding to second layer iron atoms left exposed following surface oxygen atom abstraction resulting in the formation of phosgene (COCl 2), only appears in the case of reaction with CCl 4. The reaction mechanism and active site requirements for CCl 4 degradation on iron oxide surfaces are discussed in light of this evidence and in the context of our previously reported results from Auger electron spectroscopy (AES), LEED, temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy studies.

Cucurbit[6]uril: A Possible Host for Noble Gas Atoms.

PubMed

Pan, Sudip; Mandal, Subhajit; Chattaraj, Pratim K

2015-08-27

Density functional and ab initio molecular dynamics studies are carried out to investigate the stability of noble gas encapsulated cucurbit[6]uril (CB[6]) systems. Interaction energy, dissociation energy and dissociation enthalpy are calculated to understand the efficacy of CB[6] in encapsulating noble gas atoms. CB[6] could encapsulate up to three Ne atoms having dissociation energy (zero-point energy corrected) in the range of 3.4-4.1 kcal/mol, whereas due to larger size, only one Ar or Kr atom encapsulated analogues would be viable. The dissociation energy value for the second Ar atom is only 1.0 kcal/mol. On the other hand, the same for the second Kr is -0.5 kcal/mol, implying the instability of the system. The noble gas dissociation processes are endothermic in nature, which increases gradually along Ne to Kr. Kr encapsulated analogue is found to be viable at room temperature. However, low temperature is needed for Ne and Ar encapsulated analogues. The temperature-pressure phase diagram highlights the region in which association and dissociation processes of Kr@CB[6] would be favorable. At ambient temperature and pressure, CB[6] may be used as an effective noble gas carrier. Wiberg bond indices, noncovalent interaction indices, electron density, and energy decomposition analyses are used to explore the nature of interaction between noble gas atoms and CB[6]. Dispersion interaction is found to be the most important term in the attraction energy. Ne and Ar atoms in one Ng entrapped analogue are found to stay inside the cavity of CB[6] throughout the simulation at 298 K. However, during simulation Ng2 units in Ng2@CB[6] flip toward the open faces of CB[6]. After 1 ps, one Ne atom of Ne3@CB[6] almost reaches the open face keeping other two Ne atoms inside. At lower temperature (77 K), all the Ng atoms in Ngn@CB[6] remain well inside the cavity of CB[6] throughout the simulation time (1 ps).

Dissociation of neural mechanisms underlying orientation processing in humans

PubMed Central

Ling, Sam; Pearson, Joel; Blake, Randolph

2009-01-01

Summary Orientation selectivity is a fundamental, emergent property of neurons in early visual cortex, and discovery of that property [1, 2] dramatically shaped how we conceptualize visual processing [3–6]. However, much remains unknown about the neural substrates of these basic building blocks of perception, and what is known primarily stems from animal physiology studies. To probe the neural concomitants of orientation processing in humans, we employed repetitive transcranial magnetic stimulation (rTMS) to attenuate neural responses evoked by stimuli presented within a local region of the visual field. Previous physiological studies have shown that rTMS can significantly suppress the neuronal spiking activity, hemodynamic responses, and local field potentials within a focused cortical region [7, 8]. By suppressing neural activity with rTMS, we were able to dissociate components of the neural circuitry underlying two distinct aspects of orientation processing: selectivity and contextual effects. Orientation selectivity gauged by masking was unchanged by rTMS, whereas an otherwise robust orientation repulsion illusion was weakened following rTMS. This dissociation implies that orientation processing relies on distinct mechanisms, only one of which was impacted by rTMS. These results are consistent with models positing that orientation selectivity is largely governed by the patterns of convergence of thalamic afferents onto cortical neurons, with intracortical activity then shaping population responses contained within those orientation-selective cortical neurons. PMID:19682905

Increased binding of 5-HT1A receptors in a dissociative amnesic patient after the recovery process.

PubMed

Kitamura, Soichiro; Yasuno, Fumihiko; Inoue, Makoto; Kosaka, Jun; Kiuchi, Kuniaki; Matsuoka, Kiwamu; Kishimoto, Toshifumi; Suhara, Tetsuya

2014-10-30

Dissociative amnesia is characterized by an inability to retrieve information already saved in memories. 5-HT has some role in neural regulatory control and may be related to the recovery from dissociative amnesia. To examine the role of 5-HT1A receptors in the recovery from dissociative amnesia, we performed two positron emission tomography (PET) scans on a 30-year-old patient of dissociative amnesia using [(11)C]WAY-100635, the first at amnesic state, and the second at the time he had recovered. Exploratory voxel-based analysis (VBA) was performed using SPM software. 5-HT1A BPND images were compared between the patient at amnesic and recovery states and healthy subjects (14 males, mean age 29.8 ± 6.45) with Jack-knife analysis. 5-HT1A receptor bindings of the patient at the recovery state were significantly higher than those of healthy subjects in the right superior and middle frontal cortex, left inferior frontal and orbitofrontal cortex and bilateral inferior temporal cortex. The increase in BPND values of recovery state was beyond 10% of those of amnesia state in these regions except in the right superior frontal cortex. We considered that neural regulatory control by the increase of 5-HT1A receptors in cortical regions played a role in the recovery from dissociative amnesia. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Ab initio reaction pathways for photodissociation and isomerization of nitromethane on four singlet potential energy surfaces with three roaming paths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isegawa, Miho; Liu, Fengyi; Morokuma, Keiji

2014-06-28

Photodissociation pathways of nitromethane following π → π{sup *} electronic excitation are reported. The potential energy surfaces for four lowest singlet states are explored, and structures of many intermediates, dissociation limits, transition states, and minimum energy conical intersections were determined using the automated searching algorism called the global reaction route mapping strategy. Geometries are finally optimized at CASSCF(14e,11o) level and energies are computed at CAS(14o,11e)PT2 level. The calculated preferable pathways and important products qualitatively explain experimental observations. The major photodissociation product CH{sub 3} and NO{sub 2} ({sup 2}B{sub 2}) is formed by direct dissociation from the S{sub 1} state. Importantmore » pathways involving S{sub 1} and S{sub 0} states for production of various dissociation products CH{sub 3}NO + O ({sup 1}D), CH{sub 3}O(X{sup 2}E) + NO (X{sup 2}Π), CH{sub 2}NO + OH, and CH{sub 2}O + HNO, as well as various isomerization pathways have been identified. Three roaming processes also have been identified: the O atom roaming in O dissociation from CH{sub 3}NO{sub 2}, the OH radical roaming in OH dissociation from CH{sub 2}N(O)(OH), and the NO roaming in NO dissociation from CH{sub 3}ONO.« less

Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

USGS Publications Warehouse

Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

2013-01-01

As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

A Combined Theoretical and Experimental Study of Dissociation of Charge Transfer States at the Donor-Acceptor Interface of Organic Solar Cells.

PubMed

Tscheuschner, Steffen; Bässler, Heinz; Huber, Katja; Köhler, Anna

2015-08-13

The observation that in efficient organic solar cells almost all electron-hole pairs generated at the donor-acceptor interface escape from their mutual coulomb potential remains to be a conceptual challenge. It has been argued that it is the excess energy dissipated in the course of electron or hole transfer at the interface that assists this escape process. The current work demonstrates that this concept is unnecessary to explain the field dependence of electron-hole dissociation. It is based upon the formalism developed by Arkhipov and co-workers as well as Baranovskii and co-workers. The key idea is that the binding energy of the dissociating "cold" charge-transfer state is reduced by delocalization of the hole along the polymer chain, quantified in terms of an "effective mass", as well as the fractional strength of dipoles existent at the interface in the dark. By covering a broad parameter space, we determine the conditions for efficient electron-hole dissociation. Spectroscopy of the charge-transfer state on bilayer solar cells as well as measurements of the field dependence of the dissociation yield over a broad temperature range support the theoretical predictions.

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

PubMed

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

2016-05-05

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

The dissociation of subjective measures of mental workload and performance

NASA Technical Reports Server (NTRS)

Yeh, Y. H.; Wickens, C. D.

1984-01-01

Dissociation between performance and subjective workload measures was investigated in the theoretical framework of the multiple resources model. Subjective measures do not preserve the vector characteristics in the multidimensional space described by the model. A theory of dissociation was proposed to locate the sources that may produce dissociation between the two workload measures. According to the theory, performance is affected by every aspect of processing whereas subjective workload is sensitive to the amount of aggregate resource investment and is dominated by the demands on the perceptual/central resources. The proposed theory was tested in three experiments. Results showed that performance improved but subjective workload was elevated with an increasing amount of resource investment. Furthermore, subjective workload was not as sensitive as was performance to differences in the amount of resource competition between two tasks. The demand on perceptual/central resources was found to be the most salient component of subjective workload. Dissociation occurred when the demand on this component was increased by the number of concurrent tasks or by the number of display elements. However, demands on response resources were weighted in subjective introspection as much as demands on perceptual/central resources. The implications of these results for workload practitioners are described.

Undergraduate Experiment with Fractal Diffraction Gratings

ERIC Educational Resources Information Center

Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

2011-01-01

We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

Mechanisms and energetics of hydride dissociation reactions on surfaces of plasma-deposited silicon thin films

NASA Astrophysics Data System (ADS)

Singh, Tejinder; Valipa, Mayur S.; Mountziaris, T. J.; Maroudas, Dimitrios

2007-11-01

We report results from a detailed analysis of the fundamental silicon hydride dissociation processes on silicon surfaces and discuss their implications for the surface chemical composition of plasma-deposited hydrogenated amorphous silicon (a-Si:H) thin films. The analysis is based on a synergistic combination of first-principles density functional theory (DFT) calculations of hydride dissociation on the hydrogen-terminated Si(001)-(2×1) surface and molecular-dynamics (MD) simulations of adsorbed SiH3 radical precursor dissociation on surfaces of MD-grown a-Si :H films. Our DFT calculations reveal that, in the presence of fivefold coordinated surface Si atoms, surface trihydride species dissociate sequentially to form surface dihydrides and surface monohydrides via thermally activated pathways with reaction barriers of 0.40-0.55eV. The presence of dangling bonds (DBs) results in lowering the activation barrier for hydride dissociation to 0.15-0.20eV, but such DB-mediated reactions are infrequent. Our MD simulations on a-Si :H film growth surfaces indicate that surface hydride dissociation reactions are predominantly mediated by fivefold coordinated surface Si atoms, with resulting activation barriers of 0.35-0.50eV. The results are consistent with experimental measurements of a-Si :H film surface composition using in situ attenuated total reflection Fourier transform infrared spectroscopy, which indicate that the a-Si :H surface is predominantly covered with the higher hydrides at low temperatures, while the surface monohydride, SiH(s ), becomes increasingly more dominant as the temperature is increased.

Isotherm-Based Thermodynamic Models for Solute Activities of Organic Acids with Consideration of Partial Dissociation.

PubMed

Nandy, Lucy; Ohm, Peter B; Dutcher, Cari S

2016-06-23

Organic acids make up a significant fraction of the organic mass in atmospheric aerosol particles. The calculation of gas-liquid-solid equilibrium partitioning of the organic acid is therefore critical for accurate determination of atmospheric aerosol physicochemical properties and processes such as new particle formation and activation to cloud condensation nuclei. Previously, an adsorption isotherm-based statistical thermodynamic model was developed for capturing solute concentration-activity relationships for multicomponent aqueous solutions over the entire concentration range (Dutcher et al. J. Phys. Chem. C/A 2011, 2012, 2013), with model parameters for energies of adsorption successfully related to dipole-dipole electrostatic forces in solute-solvent and solvent-solvent interactions for both electrolytes and organics (Ohm et al. J. Phys. Chem. A 2015). However, careful attention is needed for weakly dissociating semivolatile organic acids. Dicarboxylic acids, such as malonic acid and glutaric acid are treated here as a mixture of nondissociated organic solute (HA) and dissociated solute (H(+) + A(-)). It was found that the apparent dissociation was greater than that predicted by known dissociation constants alone, emphasizing the effect of dissociation on osmotic and activity coefficient predictions. To avoid additional parametrization from the mixture approach, an expression was used to relate the Debye-Hückel hard-core collision diameter to the adjustable solute-solvent intermolecular distance. An improved reference state treatment for electrolyte-organic aqueous mixtures, such as that observed here with partial dissociation, has also been proposed. This work results in predictive correlations for estimation of organic acid and water activities for which there is little or no activity data.

Dissociation of Heme–Globin Complexes by Blackbody Infrared Radiative Dissociation: Molecular Specificity in the Gas Phase?

PubMed Central

Gross, Deborah S.; Zhao, Yuexing; Williams, Evan R.

2005-01-01

The temperature dependence of the unimolecular kinetics for dissociation of the heme group from holo-myoglobin (Mb) and holo-hemoglobin α-chain (Hb-α) was investigated with blackbody infrared radiative dissociation (BIRD). The rate constant for dissociation of the 9 + charge state of Mb formed by electrospray ionization from a “pseudo-native” solution is 60% lower than that of Hb-α at each of the temperatures investigated. In solutions of pH 5.5–8.0, the thermal dissociation rate for Mb is also lower than that of HB-α (Hargrove, M. S. et al. J. Biol. Chem. 1994, 269, 4207–4214). Thus, Mb is thermally more stable with respect to heme loss than Hb-α both in the gas phase and in solution. The Arrhenius activation parameters for both dissociation processes are indistinguishable within the current experimental error (activation energy 0.9 eV and pre-exponential factor of 108–10 s−1). The 9+ to 12+ charge states of Mb have similar Arrhenius parameters when these ions are formed from pseudo-native solutions. In contrast, the activation energies and pre-exponential factors decrease from 0.8 to 0.3 eV and 107 to 102 s−1, respectively, for the 9 + to 12 + charge states formed from acidified solutions in which at least 50% of the secondary structure is lost. These results demonstrate that gas-phase Mb ions retain clear memory of the composition of the solution from which they are formed and that these differences can be probed by BIRD. PMID:16479269

Dissociation of heme-globin complexes by blackbody infrared radiative dissociation: molecular specificity in the gas phase?

PubMed

Gross, D S; Zhao, Y; Williams, E R

1997-05-01

The temperature dependence of the unimolecular kinetics for dissociation of the heme group from holo-myoglobin (Mb) and holo-hemoglobin alpha-chain (Hb-alpha) was investigated with blackbody infrared radiative dissociation (BIRD). The rate constant for dissociation of the 9 + charge state of Mb formed by electrospray ionization from a "pseudo-native" solution is 60% lower than that of Hb-alpha at each of the temperatures investigated. In solutions of pH 5.5-8.0, the thermal dissociation rate for Mb is also lower than that of HB-alpha (Hargrove, M. S. et al. J. Biol. Chem.1994, 269, 4207-4214). Thus, Mb is thermally more stable with respect to heme loss than Hb-alpha both in the gas phase and in solution. The Arrhenius activation parameters for both dissociation processes are indistinguishable within the current experimental error (activation energy 0.9 eV and pre-exponential factor of 10(8-10) s(-1)). The 9+ to 12+ charge states of Mb have similar Arrhenius parameters when these ions are formed from pseudo-native solutions. In contrast, the activation energies and pre-exponential factors decrease from 0.8 to 0.3 eV and 10(7) to 10(2) s(-1), respectively, for the 9 + to 12 + charge states formed from acidified solutions in which at least 50% of the secondary structure is lost. These results demonstrate that gas-phase Mb ions retain clear memory of the composition of the solution from which they are formed and that these differences can be probed by BIRD.

Functional connectivity of dissociation in patients with psychogenic non-epileptic seizures.

PubMed

van der Kruijs, Sylvie J M; Bodde, Nynke M G; Vaessen, Maarten J; Lazeron, Richard H C; Vonck, Kristl; Boon, Paul; Hofman, Paul A M; Backes, Walter H; Aldenkamp, Albert P; Jansen, Jacobus F A

2012-03-01

Psychogenic non-epileptic seizures (PNES) resemble epileptic seizures, but lack epileptiform brain activity. Instead, the cause is assumed to be psychogenic. An abnormal coping strategy may be exhibited by PNES patients, as indicated by their increased tendency to dissociate. Investigation of resting-state networks may reveal altered routes of information and emotion processing in PNES patients. The authors therefore investigated whether PNES patients differ from healthy controls in their resting-state functional connectivity characteristics and whether these connections are associated with the tendency to dissociate. 11 PNES patients without psychiatric comorbidity and 12 healthy controls underwent task-related paradigms (picture-encoding and Stroop paradigms) and resting-state functional MRI (rsfMRI). Global cognitive performance was tested using the Raven's Matrices test and participants completed questionnaires for evaluating dissociation. Functional connectivity analysis on rsfMRI was based on seed regions extracted from task-related fMRI activation maps. The patients displayed a significantly lower cognitive performance and significantly higher dissociation scores. No significant differences were found between the picture-encoding and Stroop colour-naming activation maps between controls and patients with PNES. However, functional connectivity maps from the rsfMRI were statistically different. For PNES patients, stronger connectivity values between areas involved in emotion (insula), executive control (inferior frontal gyrus and parietal cortex) and movement (precentral sulcus) were observed, which were significantly associated with dissociation scores. The abnormal, strong functional connectivity in PNES patients provides a neurophysiological correlate for the underlying psychoform and somatoform dissociation mechanism where emotion can influence executive control, resulting in altered motor function (eg, seizure-like episodes).

Deficit in figure-ground segmentation following closed head injury.

PubMed

Baylis, G C; Baylis, L L

1997-08-01

Patient CB showed a severe impairment in figure-ground segmentation following a closed head injury. Unlike normal subjects, CB was unable to parse smaller and brighter parts of stimuli as figure. Moreover, she did not show the normal effect that symmetrical regions are seen as figure, although she was able to make overt judgments of symmetry. Since she was able to attend normally to isolated objects, CB demonstrates a dissociation between figure ground segmentation and subsequent processes of attention. Despite her severe impairment in figure-ground segmentation, CB showed normal 'parallel' single feature visual search. This suggests that figure-ground segmentation is dissociable from 'preattentive' processes such as visual search.

Insights into dissociative electron transfer in esterified shikonin semiquinones by in situ ESR/UV-Vis spectroelectrochemistry.

PubMed

Armendáriz-Vidales, G; Frontana, C

2015-11-21

In this work, electrogenerated anion and dianion species from shikonin and its ester derivative isovalerylshikonin were characterized by means of ESR/UV-Vis spectroelectrochemistry. Analysis of the spectra supported the proposal that stepwise dissociative electron transfer (DET) takes place during the second reduction process of the esterified compound. Quantum chemical calculations were performed for validating the occurrence of this mechanistic pathway and for obtaining thermodynamic information on the electron transfer process; ΔG(cleavage)(0) was estimated to be -0.45 eV, considering that the two possible products of the overall reaction scheme are both a quinone and carboxylate anions.

Revisiting Fromm's passions as presaging contemporary views of affect and dissociation.

PubMed

Harrell, Valentina

2002-01-01

Fromm viewed intrapsychic dynamic processes as having their origin in a generalized organic life force that gets transformed into psychic energy called passions. He is acknowledged as one of the most original, creative writers of the mid-20th century whose fertile mind and humanistic sensibilities synthesized the domains of psychoanalysis, social philosophy, and politics. His unyielding belief that the development of the individual psyche is inseparable from its two-way interaction with a lived relational and cultural context presaged the evolution of the relational perspective in psychoanalysis, and his concept of passions foreshadowed contemporary neuroscientific theories of affect and its role in intrapsychic life and self-identity formation. Damasio's theory of emotions is reviewed as a specific example of the current revamping of psychoanalytic theory as bottom-up information processing, that is, the integrating and synthesizing of affective experience and memory (preverbal mentalization) as fueling the creation of a narrative self. Fromm's discussions of dissociation are linked both to Damasio's core self experiences and to Bromberg's conceptualization of psychoanalysis of dissociative experience as a process of "standing in the spaces." And finally, Fromm's descriptions of psychoanalysis as an art are linked to Schon's action-oriented theory of practical knowledge.

Body-part specific interactions of action verb processing with motor behaviour.

PubMed

Klepp, Anne; Niccolai, Valentina; Sieksmeyer, Jan; Arnzen, Stephanie; Indefrey, Peter; Schnitzler, Alfons; Biermann-Ruben, Katja

2017-06-15

The interaction of action-related language processing with actual movement is an indicator of the functional role of motor cortical involvement in language understanding. This paper describes two experiments using single action verb stimuli. Motor responses were performed with the hand or the foot. To test the double dissociation of language-motor facilitation effects within subjects, Experiments 1 and 2 used a priming procedure where both hand and foot reactions had to be performed in response to different geometrical shapes, which were preceded by action verbs. In Experiment 1, the semantics of the verbs could be ignored whereas Experiment 2 included semantic decisions. Only Experiment 2 revealed a clear double dissociation in reaction times: reactions were facilitated when preceded by verbs describing actions with the matching effector. In Experiment 1, by contrast, there was an interaction between verb-response congruence and a semantic variable related to motor features of the verbs. Thus, the double dissociation paradigm of semantic motor priming was effective, corroborating the role of the motor system in action-related language processing. Importantly, this effect was body part specific. Copyright © 2017 Elsevier B.V. All rights reserved.

Preserved processing of musical structure in a person with agrammatic aphasia.

PubMed

Slevc, L Robert; Faroqi-Shah, Yasmeen; Saxena, Sadhvi; Okada, Brooke M

2016-12-01

Evidence for shared processing of structure (or syntax) in language and in music conflicts with neuropsychological dissociations between the two. However, while harmonic structural processing can be impaired in patients with spared linguistic syntactic abilities (Peretz, I. (1993). Auditory atonalia for melodies. Cognitive Neuropsychology, 10, 21-56. doi:10.1080/02643299308253455), evidence for the opposite dissociation-preserved harmonic processing despite agrammatism-is largely lacking. Here, we report one such case: HV, a former musician with Broca's aphasia and agrammatic speech, was impaired in making linguistic, but not musical, acceptability judgments. Similarly, she showed no sensitivity to linguistic structure, but normal sensitivity to musical structure, in implicit priming tasks. To our knowledge, this is the first non-anecdotal report of a patient with agrammatic aphasia demonstrating preserved harmonic processing abilities, supporting claims that aspects of musical and linguistic structure rely on distinct neural mechanisms.

A neuroconstructivist model of past tense development and processing.

PubMed

Westermann, Gert; Ruh, Nicolas

2012-07-01

We present a neural network model of learning and processing the English past tense that is based on the notion that experience-dependent cortical development is a core aspect of cognitive development. During learning the model adds and removes units and connections to develop a task-specific final architecture. The model provides an integrated account of characteristic errors during learning the past tense, adult generalization to pseudoverbs, and dissociations between verbs observed after brain damage in aphasic patients. We put forward a theory of verb inflection in which a functional processing architecture develops through interactions between experience-dependent brain development and the structure of the environment, in this case, the statistical properties of verbs in the language. The outcome of this process is a structured processing system giving rise to graded dissociations between verbs that are easy and verbs that are hard to learn and process. In contrast to dual-mechanism accounts of inflection, we argue that describing dissociations as a dichotomy between regular and irregular verbs is a post hoc abstraction and is not linked to underlying processing mechanisms. We extend current single-mechanism accounts of inflection by highlighting the role of structural adaptation in development and in the formation of the adult processing system. In contrast to some single-mechanism accounts, we argue that the link between irregular inflection and verb semantics is not causal and that existing data can be explained on the basis of phonological representations alone. This work highlights the benefit of taking brain development seriously in theories of cognitive development. Copyright 2012 APA, all rights reserved.

Unconscious gender bias in fame judgments?

PubMed

Buchner, A; Wippich, W

1996-01-01

In two experiments the conditions of, and the processes leading to, gender biases in fame judgments were investigated. In Experiment 1, the gender bias was not reduced in a condition that alerted participants to the gender of the names. In Experiment 2, participants' sex-role orientation, but not their gender, was related to the gender bias. The process dissociation procedure was used in both experiments in an attempt to separate conscious and unconscious memory processes contributing to the gender bias. Using L.L. Jacoby's 1991) original measurement model there appeared to be evidence for unconscious influences on the gender bias in fame judgments. Unfortunately, this evidence disappeared when a model was used that takes guessing and, hence, response biases into account, which confirms that measurement models that ignore response biases in the process dissociation procedure may lead to erroneous conclusions.

Natural Memory Beyond the Storage Model: Repression, Trauma, and the Construction of a Personal Past

PubMed Central

Axmacher, Nikolai; Do Lam, Anne T. A.; Kessler, Henrik; Fell, Juergen

2010-01-01

Naturally occurring memory processes show features which are difficult to investigate by conventional cognitive neuroscience paradigms. Distortions of memory for problematic contents are described both by psychoanalysis (internal conflicts) and research on post-traumatic stress disorder (PTSD; external traumata). Typically, declarative memory for these contents is impaired – possibly due to repression in the case of internal conflicts or due to dissociation in the case of external traumata – but they continue to exert an unconscious pathological influence: neurotic symptoms or psychosomatic disorders after repression or flashbacks and intrusions in PTSD after dissociation. Several experimental paradigms aim at investigating repression in healthy control subjects. We argue that these paradigms do not adequately operationalize the clinical process of repression, because they rely on an intentional inhibition of random stimuli (suppression). Furthermore, these paradigms ignore that memory distortions due to repression or dissociation are most accurately characterized by a lack of self-referential processing, resulting in an impaired integration of these contents into the self. This aspect of repression and dissociation cannot be captured by the concept of memory as a storage device which is usually employed in the cognitive neurosciences. It can only be assessed within the framework of a constructivist memory concept, according to which successful memory involves a reconstruction of experiences such that they fit into a representation of the self. We suggest several experimental paradigms that allow for the investigation of the neural correlates of repressed memories and trauma-induced memory distortions based on a constructivist memory concept. PMID:21151366

Dissociation of heavy quarkonium in hot QCD medium in a quasiparticle model

NASA Astrophysics Data System (ADS)

Agotiya, Vineet Kumar; Chandra, Vinod; Jamal, M. Yousuf; Nilima, Indrani

2016-11-01

Following a recent work on the effective description of the equations of state for hot QCD obtained from a hard thermal loop expression for the gluon self-energy, in terms of the quasigluons and quasiquarks and antiquarks with respective effective fugacities, the dissociation process of heavy quarkonium in hot QCD medium has been investigated. This has been done by investigating the medium modification to a heavy quark potential. The medium-modified potential has a quite different form (a long-range Coulomb tail in addition to the usual Yukawa term) in contrast to the usual picture of Debye screening. The flavor dependence binding energies of the heavy quarkonia states and the dissociation temperature have been obtained by employing the Debye mass for pure gluonic and full QCD case computed employing the quasiparticle picture. Thus, estimated dissociation patterns of the charmonium and bottomonium states, considering Debye mass from different approaches in the pure gluonic case and full QCD, have shown good agreement with the other potential model studies.

Theoretical study of the photodissociation of Li(2)+ in one-color intense laser fields.

PubMed

Li, Yuanjun; Jiang, Wanyi; Khait, Yuriy G; Hoffmann, Mark R

2011-05-07

A theoretical treatment of the photodissociation of the molecular ion Li(2) (+) in one-color intense laser fields, using the time-dependent wave packet approach in a Floquet Born-Oppenheimer representation, is presented. Six electronic states 1,2 (2)Σ(g)(+), 1,2 (2)Σ(u)(+), 1 (2)Π(g), and 1 (2)Π(u) are of relevance in this simulation and have been included. The dependences of the fragmental dissociation probabilities and kinetic energy release (KER) spectra on pulse width, peak intensity, polarization angle, wavelength, and initial vibrational level are analyzed to interpret the influence of control parameters of the external field. Three main dissociation channels, 1 (2)Σ(g)(+) (m = -1), 2 (2)Σ(g)(+) (m = -2), and 2 (2)Σ(u)(+) (m = -3), are seen to dominate the dissociation processes under a wide variety of laser conditions and give rise to well separated groups of KER features. Different dissociation mechanisms for the involved Floquet channels are discussed.

A combined thermal dissociation and electron impact ionization source for radioactive ion beam generation{sup a}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alton, G.D.; Williams, C.

1996-04-01

The probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecular feed materials with conventional, hot-cathode, electron-impact ion sources is low and consequently, the ion beams from these sources often appear as mixtures of several molecular sideband beams. This fragmentation process leads to dilution of the intensity of the species of interest for radioactive ion beam (RIB) applications where beam intensity is at a premium. We have conceived an ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high ionization efficiency characteristics of an electron impact ionization source that will, inmore » principle, overcome this handicap. The source concept will be evaluated as a potential candidate for use for RIB generation at the Holifield Radioactive Ion Beam Facility, now under construction at the Oak Ridge National Laboratory. The design features and principles of operation of the source are described in this article. {copyright} {ital 1996 American Institute of Physics.}« less

A combined thermal dissociation and electron impact ionization source for radioactive ion beam generation (abstract){sup a}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alton, G.D.; Williams, C.

1996-03-01

The probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecular feed materials with conventional, hot-cathode, electron-impact ion sources is low and consequently, the ion beams from these sources often appear as mixtures of several molecular sideband beams. This fragmentation process leads to dilution of the intensity of the species of interest for radioactive ion beam (RIB) applications where beam intensity is at a premium. We have conceived an ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high ionization efficiency characteristics of an electron impact ionization source that will, inmore » principle, overcome this handicap. The source concept will be evaluated as a potential candidate for use for RIB generation at the Holifield Radioactive Ion Beam Facility, now under construction at the Oak Ridge National Laboratory. The design features and principles of operation of the source are described in this article. {copyright} {ital 1996 American Institute of Physics.}« less

Forgetting heart break: a fascinating case of transient left ventricular apical ballooning syndrome associated with dissociative amnesia.

PubMed

Toussi, Amir; Bryk, Jodie; Alam, Abdulkader

2014-01-01

Transient left ventricular apical ballooning syndrome (TLVABS), also known as takotsubo cardiomyopathy, is characterized by transient left ventricular dysfunction, electrocardiographic changes, and release of myocardial enzymes that mimic acute myocardial infarction in patients without angiographic evidence of coronary artery disease. Most patients are post-menopausal women and an emotional or physiologic stressor frequently precedes the presentation. Psychogenic or dissociative amnesia is a memory disorder characterized by sudden retrograde memory loss with inability to recall personal information said to occur for a period of time ranging from hours to years after a stressful event. Interestingly, the mechanism of both disorders has been linked to plasma elevation in catecholamines. Here we present the case of a 66-year-old female diagnosed with both TLVABS and dissociative amnesia following the sudden unexpected death of her sister. To our knowledge, this is surprisingly the first report of the co-occurrence of TLVABS and dissociative amnesia, two processes with a potential shared underlying etiology. © 2013.

On the ion-pair dissociation mechanisms in the small NaCl·(H2 O)6 cluster: A perspective from reaction path search calculations.

PubMed

Takayanagi, Toshiyuki; Nakatomi, Taiki; Yonetani, Yoshiteru

2018-04-20

We performed reaction path search calculations for the NaCl·(H 2 O) 6 cluster using the global reaction route mapping (GRRM) code to understand the atomic-level mechanisms of the NaCl → Na +  + Cl - ionic dissociation induced by water solvents. Low-lying minima, transition states connecting two local minima and corresponding intrinsic reaction coordinates on the potential energy surface are explored. We found that the NaCl distances at the transitions states for the dissociation pathways were distributed in a relatively wide range of 2.7-3.7 Å and that the NaCl distance at the transition state did not correlate with the commonly used solvation coordinates. This suggests that the definition of the transition states with specific structures as well as good reaction coordinate is very difficult for the ionic dissociation process even in a small water cluster. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Process for producing high purity isoolefins and dimers thereof by dissociation of ethers

DOEpatents

Smith, L.A. Jr.; Jones, E.M. Jr.; Hearn, D.

1984-05-08

Alkyl tertiary butyl ether or alkyl tertiary amyl ether is dissociated by vapor phase contact with a cation acidic exchange resin at temperatures in the range of 150 to 250 F at LHSV of 0.1 to 20 to produce a stream consisting of unreacted ether, isobutene or isoamylene and an alcohol corresponding to the alkyl radical. After the alcohol is removed, the ether/isoolefin stream may be fractionated to obtain a high purity isoolefin (99+%) or the ether/isoolefin stream can be contacted in liquid phase with a cation acidic exchange resin to selectively dimerize the isoolefin in a highly exothermic reaction, followed by fractionation of the dimerization product to produce high purity diisoolefin (97+%). In the case where the alkyl is C[sub 3] to C[sub 6] and the corresponding alcohol is produced on dissociation of the ether, combined dissociation-distillation may be carried out such that isoolefin is the overhead product and alcohol the bottom. 2 figs.

Process for producing high purity isoolefins and dimers thereof by dissociation of ethers

DOEpatents

Smith, Jr., Lawrence A.; Jones, Jr., Edward M.; Hearn, Dennis

1984-01-01

Alkyl tertiary butyl ether or alkyl tertiary amyl ether is dissociated by vapor phase contact with a cation acidic exchange resin at temperatures in the range of 150.degree. to 250.degree. F. at LHSV of 0.1 to 20 to produce a stream consisting of unreacted ether, isobutene or isoamylene and an alcohol corresponding to the alkyl radical. After the alcohol is removed, the ether/isoolefin stream may be fractionated to obtain a high purity isoolefin (99+%) or the ether/isoolefin stream can be contacted in liquid phase with a cation acidic exchange resin to selectively dimerize the isoolefin in a highly exothermic reaction, followed by fractionation of the dimerization product to produce high purity diisoolefin (97+%). In the case where the alkyl is C.sub.3 to C.sub.6 and the corresponding alcohol is produced on dissociation of the ether, combined dissociation-distillation may be carried out such that isoolefin is the overhead product and alcohol the bottom.

N-type molecular electrical doping in organic semiconductors: formation and dissociation efficiencies of charge transfer complex

NASA Astrophysics Data System (ADS)

Kim, Jae-Min; Yoo, Seung-Jun; Moon, Chang-Ki; Sim, Bomi; Lee, Jae-Hyun; Lim, Heeseon; Kim, Jeong Won; Kim, Jang-Joo

2016-09-01

Electrical doping is an important method in organic electronics to enhance device efficiency by controlling Fermi level, increasing conductivity, and reducing injection barrier from electrode. To understand the charge generation process of dopant in doped organic semiconductors, it is important to analyze the charge transfer complex (CTC) formation and dissociation into free charge carrier. In this paper, we correlate charge generation efficiency with the CTC formation and dissociation efficiency of n-dopant in organic semiconductors (OSs). The CTC formation efficiency of Rb2CO3 linearly decreases from 82.8% to 47.0% as the doping concentration increases from 2.5 mol% to 20 mol%. The CTC formation efficiency and its linear decrease with doping concentration are analytically correlated with the concentration-dependent size and number of dopant agglomerates by introducing the degree of reduced CTC formation. Lastly, the behavior of dissociation efficiency is discussed based on the picture of the statistical semiconductor theory and the frontier orbital hybridization model.

Lexical and semantic processing in the absence of word reading: evidence from neglect dyslexia.

PubMed

Làdavas, E; Umiltà, C; Mapelli, D

1997-08-01

Nine patients with left-sided neglect and nine matched control patients performed three tasks on horizontal (either normal or mirror-reversed) letter strings. The tasks were: reading aloud, making a lexical decision (word vs non-word), and making a semantic decision (living vs non-living item). Relative to controls, neglect patients performed very poorly in the reading task, whereas they performed nearly normally in the lexical and semantic tasks. This was considered to be a dissociation between direct tasks, rather than a dissociation between explicit and implicit knowledge. The explanation offered for the dissociation is in terms of both a dual-route model for reading aloud and a degraded representation of the letter string.

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

NASA Astrophysics Data System (ADS)

Jana, Irina; Nandi, Dhananjay

2018-04-01

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

An analysis of combustion studies in shock expansion tunnels and reflected shock tunnels

NASA Technical Reports Server (NTRS)

Jachimowski, Casimir J.

1992-01-01

The effect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in high-speed flows for a simulated Mach 17 flight condition was investigated by analyzing the results of comparative combustion experiments performed in a reflected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes finite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and the presence of the nonequilibrium partially dissociated oxygen in the reflected shock tunnel enhances the combustion. Methods of compensating for the effect of dissociated oxygen are discussed.

Prompt and delayed Coulomb explosion of doubly ionized hydrogen chloride molecules in intense femtosecond laser fields

NASA Astrophysics Data System (ADS)

Ma, Junyang; Li, Hui; Lin, Kang; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Li, Hanxiao; Sun, Fenghao; Qiang, Junjie; Lu, Peifen; Gong, Xiaochun; Zeng, Heping; Wu, Jian

2018-06-01

We experimentally investigate the dissociative double ionization of hydrogen chloride (HCl) molecules in intense femtosecond laser pulses. In addition to the prompt dissociation channels which occur on femtosecond timescales, long-lived hydrogen chloride dications which Coulomb-explode in flight towards the detector are clearly identified in the photoion-photoion coincidence spectrum. Different pathways leading to these prompt and delayed dissociation channels involving various bound and repulsive states of the HCl dication are discussed based on the observed kinetic energy release and momentum distributions. Our results indicate that the specific features of the HCl dication potential energy curves are responsible for the generation of the delayed fragmentation channels, which are expected to be general processes for the hydrogen halides.

Cell membrane antigen-antibody complex dissociation by the widely used glycine-HCL method: an unreliable procedure for studying antibody internalization.

PubMed

Tsaltas, G; Ford, C H

1993-02-01

Methods following the process of binding and internalization of antibodies to cell surface antigens have often employed low pH isoosmolar buffers in order to dissociate surface antigen-antibody complexes. One of the most widely used buffers is a 0.05 M glycine-HCL buffer pH 2.8. Since the efficacy of action of this buffer was critical to a series of internalization experiments employing monoclonal antibodies (Mabs) to carcinoembryonic antigen (CEA) expressing cancer cell lines in this laboratory, we tested its performance in a number of different assays. Our results indicate that this buffer only partially dissociates antigen-antibody bonds and therefore can introduce major inaccuracies in internalization experiments.

Is there a dissociative process in sleepwalking and night terrors?

PubMed Central

Hartman, D; Crisp, A; Sedgwick, P; Borrow, S

2001-01-01

The enduring and contentious hypothesis that sleepwalking and night terrors are symptomatic of a protective dissociative mechanism is examined. This is mobilised when intolerable impulses, feelings and memories escape, within sleep, the diminished control of mental defence mechanisms. They then erupt but in a limited motoric or affective form with restricted awareness and subsequent amnesia for the event. It has also been suggested that such processes are more likely when the patient has a history of major psychological trauma. In a group of 22 adult patients, referred to a tertiary sleep disorders service with possible sleepwalking/night terrors, diagnosis was confirmed both clinically and polysomnographically, and only six patients had a history of such trauma. More commonly these described sleepwalking/night terrors are associated with vivid dream-like experiences or behaviour related to flight from attack. Two such cases, suggestive of a dissociative process, are described in more detail.
The results of this study are presented largely on account of the negative findings. Scores on the dissociation questionnaire (DIS-Q) were normal, although generally higher in the small "trauma" subgroup. These were similar to scores characterising individuals with post-traumatic stress disorder. This "trauma" group also scored particularly highly on the anxiety, phobic, and depression scales of the Crown-Crisp experiential index. In contrast the "no trauma" group scored more specifically highly on the anxiety scale, along with major trends to high depression and hysteria scale scores. Two cases are presented which illustrate exceptional occurrence of later onset of sleepwalking/night terrors with accompanying post-traumatic symptoms during wakefulness. It is concluded that a history of major psychological trauma exists in only a minority of adult patients presenting with sleepwalking/night terror syndrome. In this subgroup trauma appears to dictate the subsequent content of the attacks. However, the symptoms express themselves within the form of the sleepwalking/night terror syndrome rather than as rapid eye movement sleep related nightmares. The main group of subjects with the syndrome and with no history of major psychological trauma show no clinical or DIS-Q evidence of dissociation during wakefulness. The proposition that, within the character structure of this group, the mechanism still operates but exclusively within sleep remains a possibility.


Keywords: sleepwalking; night terrors; dissociation; post-traumatic stress disorder PMID:11264487

Kinetic Investigation of Homogeneous H(2)-D(2) Equilibration Catalyzed by Pt-Au Cluster Compounds. Characterization of the Cluster [(H)Pt(AuPPh(3))(9)](NO(3))(2).

PubMed

Rubinstein, Leon I.; Pignolet, Louis H.

1996-11-06

The new Pt-Au hydrido cluster compound [(H)Pt(AuPPh(3))(9)](NO(3))(2) (3) has been synthesized and characterized by NMR, FABMS, and single-crystal X-ray diffraction [triclinic, P&onemacr;, a = 17.0452(1) Å, b = 17.4045(2) Å, c = 55.2353(1) Å, alpha = 89.891(1) degrees, beta = 85.287(1) degrees, gamma = 75.173(1) degrees, V = 15784.0(2) Å(3), Z = 4 (two molecules in asymmetric unit), residual R = 0.089 for 45 929 observed reflections and 3367 variables, Mo Kalpha radiation]. The Pt(AuP)(9) core geometry is a distorted icosahedron with three vertices vacant. The Pt-Au, Au-Au, and Au-P distances are within the normal ranges observed in other Pt-Au clusters. This cluster is a catalyst for H(2)-D(2) equilibration in homogeneous solution phase and has been used in a general mechanistic study of this reaction catalyzed by Pt-Au clusters. We previously proposed that a key step in the mechanism for catalytic H(2)-D(2) equilibration is the dissociation of a PPh(3) ligand to give a cluster with an open Au site for bonding of H(2) or D(2). This was based on qualitative observations that PPh(3) inhibited the rate of HD production with [Pt(AuPPh(3))(8)](NO(3))(2) (1) as catalyst. In order to test this hypothesis, phosphine inhibition (on the rate of HD production) and phosphine ligand exchange kinetic experiments were carried out with [(H)(PPh(3))Pt(AuPPh(3))(7)](NO(3))(2) (2) and 3. In this paper we show that the rate constant for phosphine dissociation determined from the PPh(3) inhibition rate study of H(2)-D(2) equilibration with cluster 2 is nearly identical to the rate constant for dissociative phosphine ligand exchange. The slower rate for H(2)-D(2) equilibration observed with 3 compared with 2 (5.5 x 10(-3) vs 7.7 x 10(-2) turnover s(-1)) is explained by its smaller rate constant for phosphine dissociation (2.8 x 10(-5) vs 2.9 x 10(-4) s(-1)). The fact that clusters 2 and 3 show similar kinetic behaviors suggests that the PPh(3) dissociation step in the catalytic H(2)-D(2) equilibration is general for 18-electron hydrido Pt-AuPPh(3) clusters.

[Antigen differences of genetic variants Abent+ and Abent- poliovirus vaccine strain of III type].

PubMed

Shyrobokov, V P; Kostenko, I H; Nikolaienko, I V

2003-01-01

Hybridomes--producers of monoclonal antibodies (MAB) were obtained able to differentiate the variants Abent+ and Abent- poliovirus vaccine strain in the virus neutralizing reaction. Using the obtained panel the changes of the epitope structure of capsid proteins of poliovirus variants (dissociants) were found which appeared during reproduction in cell culture. It proves the fact that there exist essential antigenic differences of superficial virion's proteins, which appear during the process of dissociation.

Destruction of Peptides and Nucleosides in Reactions with Low-Energy Electrons

NASA Astrophysics Data System (ADS)

Muftakhov, M. V.; Shchukin, P. V.

2018-05-01

Mass-spectrometry of negative ions is used to study dissociative electron capture by molecules of several nucleosides, simplest di- and tripeptides, and modified dipeptides. Energy domains and efficiencies of dissociative capture are determined for the objects under study, and threshold energies of several fragmentation processes are estimated. It is shown that cytidine and peptides are stable against fragmentation due to simple bond breaking at electron energies ranging from 0 to 1 eV.

Association/Dissociation Processes in Dense Gases.

DTIC Science & Technology

1985-08-16

temperature 0 and generally lies 1 0 ke below the dissociation limit (taken as zero energy). The central block E of highly excited " bound levels is...approximate solution of (1.1) with general V(R) "* a large body of literature (see ref. 7) exists on various schemes based on Green’s function,8...be obtained for general mass systems provided the new basic expression introduced here - for RAD(t) is adopted. A The microscopic basis of the

Quaternary Structure Heterogeneity of Oligomeric Proteins: A SAXS and SANS Study of the Dissociation Products of Octopus vulgaris Hemocyanin

PubMed Central

Spinozzi, Francesco; Mariani, Paolo; Mičetić, Ivan; Ferrero, Claudio; Pontoni, Diego; Beltramini, Mariano

2012-01-01

Octopus vulgaris hemocyanin shows a particular self-assembling pattern, characterized by a hierarchical organization of monomers. The highest molecular weight aggregate is a decamer, the stability of which in solution depends on several parameters. Different pH values, buffer compositions, H2O/D2O ratios and Hofmeister’s salts result in modifications of the aggregation state of Octopus vulgaris hemocyanin. The new QUAFIT method, recently applied to derive the structure of the decameric and the monomeric assembly from small-angle scattering data, is used here to model the polydisperse system that results from changing the solution conditions. A dataset of small-angle X-rays and neutron scattering curves is analysed by QUAFIT to derive structure, composition and concentration of different assemblies present in solution. According to the hierarchy of the association/dissociation processes and the possible number of different aggregation products in solution, each sample has been considered as a heterogeneous mixture composed of the entire decamer, the dissociated “loose” monomer and all the intermediate dissociation products. Scattering curves corresponding to given experimental conditions are well fitted by using a linear combination of single particle form factors. QUAFIT has proved to be a method of general validity to describe solutions of proteins that, even after purification processes, result to be intrinsically heterogeneous. PMID:23166737

Thermally regenerative hydrogen/oxygen fuel cell power cycles

NASA Technical Reports Server (NTRS)

Morehouse, J. H.

1986-01-01

Two innovative thermodynamic power cycles are analytically examined for future engineering feasibility. The power cycles use a hydrogen-oxygen fuel cell for electrical energy production and use the thermal dissociation of water for regeneration of the hydrogen and oxygen. The TDS (thermal dissociation system) uses a thermal energy input at over 2000 K to thermally dissociate the water. The other cycle, the HTE (high temperature electrolyzer) system, dissociates the water using an electrolyzer operating at high temperature (1300 K) which receives its electrical energy from the fuel cell. The primary advantages of these cycles is that they are basically a no moving parts system, thus having the potential for long life and high reliability, and they have the potential for high thermal efficiency. Both cycles are shown to be classical heat engines with ideal efficiency close to Carnot cycle efficiency. The feasibility of constructing actual cycles is investigated by examining process irreversibilities and device efficiencies for the two types of cycles. The results show that while the processes and devices of the 2000 K TDS exceed current technology limits, the high temperature electrolyzer system appears to be a state-of-the-art technology development. The requirements for very high electrolyzer and fuel cell efficiencies are seen as determining the feasbility of the HTE system, and these high efficiency devices are currently being developed. It is concluded that a proof-of-concept HTE system experiment can and should be conducted.

Measurement of inelastic, single- and double-diffraction cross sections in proton-proton collisions at the LHC with ALICE.

PubMed

Abelev, B; Adam, J; Adamová, D; Adare, A M; Aggarwal, M M; Aglieri Rinella, G; Agocs, A G; Agostinelli, A; Aguilar Salazar, S; Ahammed, Z; Ahmad Masoodi, A; Ahmad, N; Ahn, S A; Ahn, S U; Akindinov, A; Aleksandrov, D; Alessandro, B; Alfaro Molina, R; Alici, A; Alkin, A; Almaráz Aviña, E; Alme, J; Alt, T; Altini, V; Altinpinar, S; Altsybeev, I; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Anson, C; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arbor, N; Arcelli, S; Arend, A; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Asryan, A; Augustinus, A; Averbeck, R; Awes, T C; Äystö, J; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bailhache, R; Bala, R; Baldini Ferroli, R; Baldisseri, A; Baldit, A; Baltasar Dos Santos Pedrosa, F; Bán, J; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batyunya, B; Baumann, C; Bearden, I G; Beck, H; Behera, N K; Belikov, I; Bellini, F; Bellwied, R; Belmont-Moreno, E; Bencedi, G; Beole, S; Berceanu, I; Bercuci, A; Berdnikov, Y; Berenyi, D; Bergognon, A A E; Berzano, D; Betev, L; Bhasin, A; Bhati, A K; Bhom, J; Bianchi, N; Bianchi, L; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Bjelogrlic, S; Blanco, F; Blanco, F; Blau, D; Blume, C; Boccioli, M; Bock, N; Böttger, S; Bogdanov, A; Bøggild, H; Bogolyubsky, M; Boldizsár, L; Bombara, M; Book, J; Borel, H; Borissov, A; Bose, S; Bossú, F; Botje, M; Botta, E; Boyer, B; Braidot, E; Braun-Munzinger, P; Bregant, M; Breitner, T; Browning, T A; Broz, M; Brun, R; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Busch, O; Buthelezi, Z; Caballero Orduna, D; Caffarri, D; Cai, X; Caines, H; Calvo Villar, E; Camerini, P; Canoa Roman, V; Cara Romeo, G; Carena, F; Carena, W; Carlin Filho, N; Carminati, F; Casanova Díaz, A; Castillo Castellanos, J; Castillo Hernandez, J F; Casula, E A R; Catanescu, V; Cavicchioli, C; Ceballos Sanchez, C; Cepila, J; Cerello, P; Chang, B; Chapeland, S; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Chawla, I; Cherney, M; Cheshkov, C; Cheynis, B; Chibante Barroso, V; Chinellato, D D; Chochula, P; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Coccetti, F; Colamaria, F; Colella, D; Conesa Balbastre, G; Conesa Del Valle, Z; Constantin, P; Contin, G; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortese, P; Cortés Maldonado, I; Cosentino, M R; Costa, F; Cotallo, M E; Crescio, E; Crochet, P; Cruz Alaniz, E; Cuautle, E; Cunqueiro, L; Dainese, A; Dalsgaard, H H; Danu, A; Das, D; Das, K; Das, I; Dash, S; Dash, A; De, S; de Barros, G O V; De Caro, A; de Cataldo, G; de Cuveland, J; De Falco, A; De Gruttola, D; Delagrange, H; Deloff, A; Demanov, V; De Marco, N; Dénes, E; De Pasquale, S; Deppman, A; D Erasmo, G; de Rooij, R; Diaz Corchero, M A; Di Bari, D; Dietel, T; Di Giglio, C; Di Liberto, S; Di Mauro, A; Di Nezza, P; Divià, R; Djuvsland, Ø; Dobrin, A; Dobrowolski, T; Domínguez, I; Dönigus, B; Dordic, O; Driga, O; Dubey, A K; Dubla, A; Ducroux, L; Dupieux, P; Dutta Majumdar, M R; Dutta Majumdar, A K; Elia, D; Emschermann, D; Engel, H; Erazmus, B; Erdal, H A; Espagnon, B; Estienne, M; Esumi, S; Evans, D; Eyyubova, G; Fabris, D; Faivre, J; Falchieri, D; Fantoni, A; Fasel, M; Fearick, R; Fedunov, A; Fehlker, D; Feldkamp, L; Felea, D; Fenton-Olsen, B; Feofilov, G; Fernández Téllez, A; Ferretti, A; Ferretti, R; Festanti, A; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Francescon, A; Frankenfeld, U; Fuchs, U; Furget, C; Fusco Girard, M; Gaardhøje, J J; Gagliardi, M; Gago, A; Gallio, M; Gangadharan, D R; Ganoti, P; Garabatos, C; Garcia-Solis, E; Garishvili, I; Gerhard, J; Germain, M; Geuna, C; Gheata, M; Gheata, A; Ghidini, B; Ghosh, P; Gianotti, P; Girard, M R; Giubellino, P; Gladysz-Dziadus, E; Glässel, P; Gomez, R; Ferreiro, E G; González-Trueba, L H; González-Zamora, P; Gorbunov, S; Goswami, A; Gotovac, S; Grabski, V; Graczykowski, L K; Grajcarek, R; Grelli, A; Grigoras, C; Grigoras, A; Grigoriev, V; Grigoryan, S; Grigoryan, A; Grinyov, B; Grion, N; Gros, P; Grosse-Oetringhaus, J F; Grossiord, J-Y; Grosso, R; Guber, F; Guernane, R; Guerra Gutierrez, C; Guerzoni, B; Guilbaud, M; Gulbrandsen, K; Gunji, T; Gupta, A; Gupta, R; Gutbrod, H; Haaland, Ø; Hadjidakis, C; Haiduc, M; Hamagaki, H; Hamar, G; Han, B H; Hanratty, L D; Hansen, A; Harmanová-Tóthová, Z; Harris, J W; Hartig, M; Hasegan, D; Hatzifotiadou, D; Hayrapetyan, A; Heckel, S T; Heide, M; Helstrup, H; Herghelegiu, A; Herrera Corral, G; Herrmann, N; Hess, B A; Hetland, K F; Hicks, B; Hille, P T; Hippolyte, B; Horaguchi, T; Hori, Y; Hristov, P; Hřivnáčová, I; Huang, M; Humanic, T J; Hwang, D S; Ichou, R; Ilkaev, R; Ilkiv, I; Inaba, M; Incani, E; Innocenti, P G; Innocenti, G M; Ippolitov, M; Irfan, M; Ivan, C; Ivanov, A; Ivanov, M; Ivanov, V; Ivanytskyi, O; Jachołkowski, A; Jacobs, P M; Jang, H J; Janik, R; Janik, M A; Jayarathna, P H S Y; Jena, S; Jha, D M; Jimenez Bustamante, R T; Jirden, L; Jones, P G; Jung, H; Jusko, A; Kaidalov, A B; Kakoyan, V; Kalcher, S; Kaliňák, P; Kalliokoski, T; Kalweit, A; Kang, J H; Kaplin, V; Karasu Uysal, A; Karavichev, O; Karavicheva, T; Karpechev, E; Kazantsev, A; Kebschull, U; Keidel, R; Khan, P; Khan, S A; Khan, M M; Khanzadeev, A; Kharlov, Y; Kileng, B; Kim, S; Kim, B; Kim, T; Kim, D J; Kim, D W; Kim, J H; Kim, J S; Kim, M; Kim, M; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Klay, J L; Klein, J; Klein-Bösing, C; Kliemant, M; Kluge, A; Knichel, M L; Knospe, A G; Koch, K; Köhler, M K; Kollegger, T; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Konevskikh, A; Korneev, A; Kour, R; Kowalski, M; Kox, S; Koyithatta Meethaleveedu, G; Kral, J; Králik, I; Kramer, F; Kraus, I; Krawutschke, T; Krelina, M; Kretz, M; Krivda, M; Krizek, F; Krus, M; Kryshen, E; Krzewicki, M; Kucheriaev, Y; Kugathasan, T; Kuhn, C; Kuijer, P G; Kulakov, I; Kumar, J; Kurashvili, P; Kurepin, A B; Kurepin, A; Kuryakin, A; Kushpil, V; Kushpil, S; Kvaerno, H; Kweon, M J; Kwon, Y; Ladrón de Guevara, P; Lakomov, I; Langoy, R; La Pointe, S L; Lara, C; Lardeux, A; La Rocca, P; Lea, R; Le Bornec, Y; Lechman, M; Lee, S C; Lee, G R; Lee, K S; Lefèvre, F; Lehnert, J; Lenhardt, M; Lenti, V; León, H; Leoncino, M; León Monzón, I; León Vargas, H; Lévai, P; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Liu, L; Loggins, V R; Loginov, V; Lohn, S; Lohner, D; Loizides, C; Loo, K K; Lopez, X; López Torres, E; Løvhøiden, G; Lu, X-G; Luettig, P; Lunardon, M; Luo, J; Luparello, G; Luquin, L; Luzzi, C; Ma, K; Ma, R; Madagodahettige-Don, D M; Maevskaya, A; Mager, M; Mahapatra, D P; Maire, A; Malaev, M; Maldonado Cervantes, I; Malinina, L; Mal'Kevich, M V D; Malzacher, P; Mamonov, A; Mangotra, L; Manko, V; Manso, F; Manzari, V; Mao, Y; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Marín, A; Marin Tobon, C A; Markert, C; Marquard, M; Martashvili, I; Martinengo, P; Martínez, M I; Martínez Davalos, A; Martínez García, G; Martynov, Y; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Massacrier, L; Mastroserio, A; Matthews, Z L; Matyja, A; Mayer, C; Mazer, J; Mazzoni, M A; Meddi, F; Menchaca-Rocha, A; Mercado Pérez, J; Meres, M; Miake, Y; Milano, L; Milosevic, J; Mischke, A; Mishra, A N; Miśkowiec, D; Mitu, C; Mlynarz, J; Mohanty, B; Molnar, L; Montaño Zetina, L; Monteno, M; Montes, E; Moon, T; Morando, M; Moreira De Godoy, D A; Moretto, S; Morsch, A; Muccifora, V; Mudnic, E; Muhuri, S; Mukherjee, M; Müller, H; Munhoz, M G; Musa, L; Musso, A; Nandi, B K; Nania, R; Nappi, E; Nattrass, C; Naumov, N P; Navin, S; Nayak, T K; Nazarenko, S; Nazarov, G; Nedosekin, A; Nicassio, M; Niculescu, M; Nielsen, B S; Niida, T; Nikolaev, S; Nikolic, V; Nikulin, S; Nikulin, V; Nilsen, B S; Nilsson, M S; Noferini, F; Nomokonov, P; Nooren, G; Novitzky, N; Nyanin, A; Nyatha, A; Nygaard, C; Nystrand, J; Ochirov, A; Oeschler, H; Oh, S; Oh, S K; Oleniacz, J; Oppedisano, C; Ortiz Velasquez, A; Ortona, G; Oskarsson, A; Ostrowski, P; Otwinowski, J; Oyama, K; Ozawa, K; Pachmayer, Y; Pachr, M; Padilla, F; Pagano, P; Paić, G; Painke, F; Pajares, C; Pal, S K; Palaha, A; Palmeri, A; Papikyan, V; Pappalardo, G S; Park, W J; Passfeld, A; Pastirčák, B; Patalakha, D I; Paticchio, V; Pavlinov, A; Pawlak, T; Peitzmann, T; Pereira Da Costa, H; Pereira De Oliveira Filho, E; Peresunko, D; Pérez Lara, C E; Perez Lezama, E; Perini, D; Perrino, D; Peryt, W; Pesci, A; Peskov, V; Pestov, Y; Petráček, V; Petran, M; Petris, M; Petrov, P; Petrovici, M; Petta, C; Piano, S; Piccotti, A; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Pitz, N; Piyarathna, D B; Planinic, M; Płoskoń, M; Pluta, J; Pocheptsov, T; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polák, K; Polichtchouk, B; Pop, A; Porteboeuf-Houssais, S; Pospíšil, V; Potukuchi, B; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puchagin, S; Puddu, G; Pulvirenti, A; Punin, V; Putiš, M; Putschke, J; Quercigh, E; Qvigstad, H; Rachevski, A; Rademakers, A; Räihä, T S; Rak, J; Rakotozafindrabe, A; Ramello, L; Ramírez Reyes, A; Raniwala, S; Raniwala, R; Räsänen, S S; Rascanu, B T; Rathee, D; Read, K F; Real, J S; Redlich, K; Reichelt, P; Reicher, M; Renfordt, R; Reolon, A R; Reshetin, A; Rettig, F; Revol, J-P; Reygers, K; Riccati, L; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Rodrigues Fernandes Rabacal, B; Rodríguez Cahuantzi, M; Rodriguez Manso, A; Røed, K; Rohr, D; Röhrich, D; Romita, R; Ronchetti, F; Rosnet, P; Rossegger, S; Rossi, A; Roy, P; Roy, C; Rubio Montero, A J; Rui, R; Russo, R; Ryabinkin, E; Rybicki, A; Sadovsky, S; Šafařík, K; Sahoo, R; Sahu, P K; Saini, J; Sakaguchi, H; Sakai, S; Sakata, D; Salgado, C A; Salzwedel, J; Sambyal, S; Samsonov, V; Sanchez Castro, X; Šándor, L; Sandoval, A; Sano, M; Sano, S; Santo, R; Santoro, R; Sarkamo, J; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schreiner, S; Schuchmann, S; Schukraft, J; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, R; Segato, G; Selyuzhenkov, I; Senyukov, S; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, N; Sharma, S; Rohni, S; Shigaki, K; Shimomura, M; Shtejer, K; Sibiriak, Y; Siciliano, M; Sicking, E; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simatovic, G; Simonetti, G; Singaraju, R; Singh, R; Singha, S; Singhal, V; Sinha, B C; Sinha, T; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Son, H; Song, M; Song, J; Soos, C; Soramel, F; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stan, I; Stefanek, G; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Stolpovskiy, M; Strabykin, K; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Sukhorukov, M; Sultanov, R; Šumbera, M; Susa, T; Symons, T J M; 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Weber, M; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, A; Wilk, G; Williams, M C S; Windelband, B; Xaplanteris Karampatsos, L; Yaldo, C G; Yamaguchi, Y; Yang, H; Yang, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yoo, I-K; Yoon, J; Yu, W; Yuan, X; Yushmanov, I; Zaccolo, V; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, X; Zhang, H; Zhou, D; Zhou, Y; Zhou, F; Zhu, J; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M; Zyzak, M

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X <200 GeV/ c 2 ) [Formula: see text], and [Formula: see text], respectively at centre-of-mass energies [Formula: see text]; for double diffraction (for a pseudorapidity gap Δ η >3) σ DD / σ INEL =0.11±0.03,0.12±0.05, and [Formula: see text], respectively at [Formula: see text]. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: [Formula: see text] mb at [Formula: see text] and [Formula: see text] at [Formula: see text]. The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and proton-proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

Selective interference reveals dissociation between memory for location and colour.

PubMed

Vuontela, V; Rämä, P; Raninen, A; Aronen, H J; Carlson, S

1999-08-02

The aim was to study whether there is indication of a dissociation in processing of visuospatial and colour information in working memory in humans. Experimental subjects performed visuospatial and colour n-back tasks with and without visuospatial and colour distractive stimuli presented in the middle of the delay period to specifically affect mnemonic processing of task-related information. In the high memory-load condition, the visuospatial, but not the colour, task was selectively disrupted by visuospatial but not colour distractors. When subvocal rehearsal of the memoranda in the colour task was prevented by articulatory suppression; colour task performance was also selectively disrupted by distractors qualitatively similar to the memoranda. The results support the suggestion that visual working memory for location is processed separate from that for colour.

The Two Sides of Beauty: Laterality and the Duality of Facial Attractiveness

ERIC Educational Resources Information Center

Franklin, Robert G., Jr.; Adams, Reginald B., Jr.

2010-01-01

We hypothesized that facial attractiveness represents a dual judgment, a combination of reward-based, sexual processes, and aesthetic, cognitive processes. Herein we describe a study that demonstrates that sexual and nonsexual processes both contribute to attractiveness judgments and that these processes can be dissociated. Female participants…

A full understanding of oxygen reduction reaction mechanism on Au(1 1 1) surface

NASA Astrophysics Data System (ADS)

Yang, Yang; Dai, Changqing; Fisher, Adrian; Shen, Yanchun; Cheng, Daojian

2017-09-01

Oxygen reduction and hydrogen peroxide reduction are technologically important reactions in energy-conversion devices. In this work, a full understanding of oxygen reduction reaction (ORR) mechanism on Au(1 1 1) surface is investigated by density functional theory (DFT) calculations, including the reaction mechanisms of O2 dissociation, OOH dissociation, and H2O2 dissociation. Among these ORR mechanisms on Au(1 1 1), the activation energy of \\text{O}2* hydrogenation reaction is much lower than that of \\text{O}2* dissociation, indicating that \\text{O}2* hydrogenation reaction is more appropriate at the first step than \\text{O}2* dissociation. In the following, H2O2 can be formed with the lower activation energy compared with the OOH dissociation reaction, and finally H2O2 could be generated as a detectable product due to the high activation energy of H2O2 dissociation reaction. Furthermore, the potential dependent free energy study suggests that the H2O2 formation is thermodynamically favorable up to 0.4 V on Au(1 1 1), reducing the overpotential for 2e - ORR process. And the elementary step of first H2O formation becomes non-spontaneous at 0.4 V, indicating the difficulty of 4e - reduction pathway. Our DFT calculations show that H2O2 can be generated on Au(1 1 1) and the first electron transfer is the rate determining step. Our results show that gold surface could be used as a good catalyst for small-scale manufacture and on-site production of H2O2.

Fractionating the unitary notion of dissociation: disembodied but not embodied dissociative experiences are associated with exocentric perspective-taking

PubMed Central

Braithwaite, Jason J.; James, Kelly; Dewe, Hayley; Medford, Nick; Takahashi, Chie; Kessler, Klaus

2013-01-01

It has been argued that hallucinations which appear to involve shifts in egocentric perspective (e.g., the out-of-body experience, OBE) reflect specific biases in exocentric perspective-taking processes. Via a newly devised perspective-taking task, we examined whether such biases in perspective-taking were present in relation to specific dissociative anomalous body experiences (ABE) – namely the OBE. Participants also completed the Cambridge Depersonalization Scale (CDS; Sierra and Berrios, 2000) which provided measures of additional embodied ABE (unreality of self) and measures of derealization (unreality of surroundings). There were no reliable differences in the level of ABE, emotional numbing, and anomalies in sensory recall reported between the OBE and control group as measured by the corresponding CDS subscales. In contrast, the OBE group did provide significantly elevated measures of derealization (“alienation from surroundings” CDS subscale) relative to the control group. At the same time we also found that the OBE group was significantly more efficient at completing all aspects of the perspective-taking task relative to controls. Collectively, the current findings support fractionating the typically unitary notion of dissociation by proposing a distinction between embodied dissociative experiences and disembodied dissociative experiences – with only the latter being associated with exocentric perspective-taking mechanisms. Our findings – obtained with an ecologically valid task and a homogeneous OBE group – also call for a re-evaluation of the relationship between OBEs and perspective-taking in terms of facilitated disembodied experiences. PMID:24198776

Shock tube study of dissociation and relaxation in 1,1-difluoroethane and vinyl fluoride.

PubMed

Xu, Hui; Kiefer, John H; Sivaramakrishnan, Raghu; Giri, Binod R; Tranter, Robert S

2007-08-21

This paper reports measurements of the thermal dissociation of 1,1-difluoroethane in the shock tube. The experiments employ laser-schlieren measurements of rate for the dominant HF elimination using 10% 1,1-difluoroethane in Kr over 1500-2000 K and 43 < P < 424 torr. The vinyl fluoride product of this process then dissociates affecting the late observations. We thus include a laser schlieren study (1717-2332 K, 75 < P < 482 torr in 10 and 4% vinyl fluoride in Kr) of this dissociation. This latter work also includes a set of experiments using shock-tube time-of-flight mass spectrometry (4% vinyl fluoride in neon, 1500-1980 K, 500 < P < 1300 torr). These time-of-flight experiments confirm the theoretical expectation that the only reaction in vinyl fluoride is HF elimination. The dissociation experiments are augmented by laser schlieren measurements of vibrational relaxation (1-20% C(2)H(3)F in Kr, 415-1975 K, 5 < P < 50 torr, and 2 and 5% C(2)H(4)F(2) in Kr, 700-1350 K, 6 < P < 22 torr). These experiments exhibit very rapid relaxation, and incubation delays should be negligible in dissociation. An RRKM model of dissociation in 1,1-difluoroethane based on a G3B3 calculation of barrier and other properties fits the experiments but requires a very large DeltaE(down) of 1600 cm(-1), similar to that found in a previous examination of 1,1,1-trifluoroethane. Dissociation of vinyl fluoride is complicated by the presence of two parallel HF eliminations, both three-center and four-center. Structure calculations find nearly equal barriers for these, and TST calculations show almost identical k(infinity). An RRKM fit to the observed falloff again requires an unusually large DeltaE(down) and the experiments actually support a slightly reduced barrier. These large energy-transfer parameters now seem routine in these large fluorinated species. It is perhaps a surprising result for which there is as yet no explanation.

Numerical analysis of wellbore instability in gas hydrate formation during deep-water drilling

NASA Astrophysics Data System (ADS)

Zhang, Huaiwen; Cheng, Yuanfang; Li, Qingchao; Yan, Chuanliang; Han, Xiuting

2018-02-01

Gas hydrate formation may be encountered during deep-water drilling because of the large amount and wide distribution of gas hydrates under the shallow seabed of the South China Sea. Hydrates are extremely sensitive to temperature and pressure changes, and drilling through gas hydrate formation may cause dissociation of hydrates, accompanied by changes in wellbore temperatures, pore pressures, and stress states, thereby leading to wellbore plastic yield and wellbore instability. Considering the coupling effect of seepage of drilling fluid into gas hydrate formation, heat conduction between drilling fluid and formation, hydrate dissociation, and transformation of the formation framework, this study established a multi-field coupling mathematical model of the wellbore in the hydrate formation. Furthermore, the influences of drilling fluid temperatures, densities, and soaking time on the instability of hydrate formation were calculated and analyzed. Results show that the greater the temperature difference between the drilling fluid and hydrate formation is, the faster the hydrate dissociates, the wider the plastic dissociation range is, and the greater the failure width becomes. When the temperature difference is greater than 7°C, the maximum rate of plastic deformation around the wellbore is more than 10%, which is along the direction of the minimum horizontal in-situ stress and associated with instability and damage on the surrounding rock. The hydrate dissociation is insensitive to the variation of drilling fluid density, thereby implying that the change of the density of drilling fluids has a minimal effect on the hydrate dissociation. Drilling fluids that are absorbed into the hydrate formation result in fast dissociation at the initial stage. As time elapses, the hydrate dissociation slows down, but the risk of wellbore instability is aggravated due to the prolonged submersion in drilling fluids. For the sake of the stability of the wellbore in deep-water drilling through hydrate formation, the drilling fluid with low temperatures should be given priority. The drilling process should be kept under balanced pressures, and the drilling time should be shortened.

Early stage oxynitridation process of Si(001) surface by NO gas: Reactive molecular dynamics simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Haining; Kim, Seungchul; Lee, Kwang-Ryeol, E-mail: krlee@kist.re.kr

2016-03-28

Initial stage of oxynitridation process of Si substrate is of crucial importance in fabricating the ultrathin gate dielectric layer of high quality in advanced MOSFET devices. The oxynitridation reaction on a relaxed Si(001) surface is investigated via reactive molecular dynamics (MD) simulation. A total of 1120 events of a single nitric oxide (NO) molecule reaction at temperatures ranging from 300 to 1000 K are statistically analyzed. The observed reaction kinetics are consistent with the previous experimental or calculation results, which show the viability of the reactive MD technique to study the NO dissociation reaction on Si. We suggest the reaction pathwaymore » for NO dissociation that is characterized by the inter-dimer bridge of a NO molecule as the intermediate state prior to NO dissociation. Although the energy of the inter-dimer bridge is higher than that of the intra-dimer one, our suggestion is supported by the ab initio nudged elastic band calculations showing that the energy barrier for the inter-dimer bridge formation is much lower. The growth mechanism of an ultrathin Si oxynitride layer is also investigated via consecutive NO reactions simulation. The simulation reveals the mechanism of self-limiting reaction at low temperature and the time evolution of the depth profile of N and O atoms depending on the process temperature, which would guide to optimize the oxynitridation process condition.« less

Dissociation between awareness and spatial coding: evidence from unilateral neglect.

PubMed

Treccani, Barbara; Cubelli, Roberto; Sellaro, Roberta; Umiltà, Carlo; Della Sala, Sergio

2012-04-01

Prevalent theories about consciousness propose a causal relation between lack of spatial coding and absence of conscious experience: The failure to code the position of an object is assumed to prevent this object from entering consciousness. This is consistent with influential theories of unilateral neglect following brain damage, according to which spatial coding of neglected stimuli is defective, and this would keep their processing at the nonconscious level. Contrary to this view, we report evidence showing that spatial coding and consciousness can dissociate. A patient with left neglect, who was not aware of contralesional stimuli, was able to process their color and position. However, in contrast to (ipsilesional) consciously perceived stimuli, color and position of neglected stimuli were processed separately. We propose that individual object features, including position, can be processed without attention and consciousness and that conscious perception of an object depends on the binding of its features into an integrated percept.

Double dissociation of 'what' and 'where' processing in auditory cortex.

PubMed

Lomber, Stephen G; Malhotra, Shveta

2008-05-01

Studies of cortical connections or neuronal function in different cerebral areas support the hypothesis that parallel cortical processing streams, similar to those identified in visual cortex, may exist in the auditory system. However, this model has not yet been behaviorally tested. We used reversible cooling deactivation to investigate whether the individual regions in cat nonprimary auditory cortex that are responsible for processing the pattern of an acoustic stimulus or localizing a sound in space could be doubly dissociated in the same animal. We found that bilateral deactivation of the posterior auditory field resulted in deficits in a sound-localization task, whereas bilateral deactivation of the anterior auditory field resulted in deficits in a pattern-discrimination task, but not vice versa. These findings support a model of cortical organization that proposes that identifying an acoustic stimulus ('what') and its spatial location ('where') are processed in separate streams in auditory cortex.

An ion mobility-mass spectrometry investigation of monocyte chemoattractant protein-1

NASA Astrophysics Data System (ADS)

Schenauer, Matthew R.; Leary, Julie A.

2009-10-01

In the present article we describe the gas-phase dissociation behavior of the dimeric form of monocyte chemoattractant protein-1 (MCP-1) using quadrupole-traveling wave ion mobility spectrometry-time of flight mass spectrometry (q-TWIMS-TOF MS) (Waters Synapt(TM)). Through investigation of the 9+ charge state of the dimer, we were able to monitor dissociation product ion (monomer) formation as a function of activation energy. Using ion mobility, we were able to observe precursor ion structural changes occurring throughout the activation process. Arrival time distributions (ATDs) for the 5+ monomeric MCP-1 product ions, derived from the gas-phase dissociation of the 9+ dimer, were then compared with ATDs obtained for the 5+ MCP-1 monomer isolated directly from solution. The results show that the dissociated monomer is as compact as the monomer arising from solution, regardless of the trap collision energy (CE) used in the dissociation. The solution-derived monomer, when collisionally activated, also resists significant unfolding within measure. Finally, we compared the collisional activation data for the MCP-1 dimer with an MCP-1 dimer non-covalently bound to a single molecule of the semi-synthetic glycosaminoglycan (GAG) analog Arixtra(TM); the latter a therapeutic anti-thrombin III-activating pentasaccharide. We observed that while dimeric MCP-1 dissociated at relatively low trap CEs, the Arixtra-bound dimer required much higher energies, which also induced covalent bond cleavage in the bound Arixtra molecule. Both the free and Arixtra-bound dimers became less compact and exhibited longer arrival times with increasing trap CEs, albeit the Arixtra-bound complex at slightly higher energies. That both dimers shifted to longer arrival times with increasing activation energy, while the dissociated MCP-1 monomers remained compact, suggests that the longer arrival times of the Arixtra-free and Arixtra-bound dimers may represent a partial breach of non-covalent interactions between the associated MCP-1 monomers, rather than extensive unfolding of individual subunits. The fact that Arixtra preferentially binds MCP-1 dimers and prevents dimer dissociation at comparable activation energies to the Arixtra-free dimer, may suggest that the drug interacts across the two monomers, thereby inhibiting their dissociation.

Biexciton relaxation associated with dissociation into a surface polariton pair in semiconductor films

NASA Astrophysics Data System (ADS)

Mitsumori, Yasuyoshi; Matsuura, Shimpei; Uchiyama, Shoichi; Saito, Kentarao; Edamatsu, Keiichi; Nakayama, Masaaki; Ajiki, Hiroshi

2018-04-01

We study the biexciton relaxation process in CuCl films ranging from 6 to 200 nm. The relaxation time is measured as the dephasing time and the lifetime. We observe a unique thickness dependence of the biexciton relaxation time and also obtain an ultrafast relaxation time with a timescale as short as 100 fs, while the exciton lifetime monotonically decreases with increasing thickness. By analyzing the exciton-photon coupling energy for a surface polariton, we theoretically calculate the biexciton relaxation time as a function of the thickness. The calculated dependence qualitatively reproduces the observed relaxation time, indicating that the biexciton dissociation into a surface polariton pair is one of the major biexciton relaxation processes.

Effects of contaminants in CO2 lasers.

NASA Technical Reports Server (NTRS)

Smith, N. S.

1973-01-01

A theoretical model which includes the effects of contaminants is developed for the high flow electric discharge CO2-N2-He laser. The model couples the excitation and relaxation processes, CO2 dissociation, and negative ion formation with the flow processes. An analysis of the effects of CO, O2, NO, and N2O impurities on the average small signal gain is presented. CO decreases the gain by collisional depopulation of the upper laser level, and O2, NO, and N2O reduce the gain by decreasing the electron density by forming stable negative ions. In particular, N2O exhibits a strong quenching effect because of its large dissociation cross section for the formation of O(-).

Dehydrogenation involved Coulomb explosion of molecular C2H4FBr in an intense laser field

NASA Astrophysics Data System (ADS)

Pei, Minjie; Yang, Yan; Zhang, Jian; Sun, Zhenrong

2018-04-01

The dissociative double ionization (DDI) of molecular 1-fluo-2-bromoethane (FBE) in an intense laser field has been investigated by dc-slice imaging technology. The DDI channels involved with dehydrogenation are revealed and it's believed both the charge distribution and the bound character of real potential energy surfaces of parent ions play important roles in the dissociation process. The relationship between the potential energy surfaces of the precursor species and the photofragment ejection angles are also discussed and analyzed. Furthermore, the competition between the DDI channels has been studied and the Csbnd C bond cleavages dominate the DDI process at relative higher laser intensity.

Distorted estimates of implicit and explicit learning in applications of the process-dissociation procedure to the SRT task.

PubMed

Stahl, Christoph; Barth, Marius; Haider, Hilde

2015-12-01

We investigated potential biases affecting the validity of the process-dissociation (PD) procedure when applied to sequence learning. Participants were or were not exposed to a serial reaction time task (SRTT) with two types of pseudo-random materials. Afterwards, participants worked on a free or cued generation task under inclusion and exclusion instructions. Results showed that pre-experimental response tendencies, non-associative learning of location frequencies, and the usage of cue locations introduced bias to PD estimates. These biases may lead to erroneous conclusions regarding the presence of implicit and explicit knowledge. Potential remedies for these problems are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

VUV dissociative excitation cross sections of H2O, NH3, and CH4 by electron impact. [Vacuum Ultra-Violet

NASA Technical Reports Server (NTRS)

Morgan, H. D.; Mentall, J. E.

1974-01-01

Absolute excitation functions for excited fragments resulting from electron bombardment of H2O, NH3, and CH4 by low-energy electrons (0 to 300 eV) have been measured in the vacuum ultraviolet (1100 to 1950 A). The predominant emission for each molecule was the H Lyman-alpha line, while the O I, N I, C I, and C II emissions were at least an order of magnitude weaker. Absolute cross sections at 100 eV are given along with the appearance potential of the various processes and the possible dissociative-excitation channels through which such processes proceed.

Are major dissociative disorders characterized by a qualitatively different kind of dissociation?

PubMed

Rodewald, Frauke; Dell, Paul F; Wilhelm-Gossling, Claudia; Gast, Ursula

2011-01-01

A total of 66 patients with a major dissociative disorder, 54 patients with nondissociative disorders, and 30 nonclinical controls were administered the Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised, the Dissociative Experiences Scale, the Multidimensional Inventory of Dissociation, and the Symptom Checklist 90-Revised. Dissociative patients reported significantly more dissociative and nondissociative symptoms than did nondissociative patients and nonclinical controls. When general psychopathology was controlled, the dissociation scores of dissociative patients were still significantly higher than those of both other groups, whereas the dissociation scores of nondissociative patients and nonclinical controls no longer differed. These findings appear to be congruent with a typological model of dissociation that distinguishes between 2 qualitatively different kinds of dissociation. Specifically, the results of this study suggest that the dissociation that occurs in major dissociative disorders (i.e., dissociative identity disorder [DID] and dissociative disorder not otherwise specified, Type 1 [DDNOS-1]) is qualitatively different from the dissociation that occurs in persons who do not have a dissociative disorder. In contrast to previous research, the dissociation of persons who do not have a dissociative disorder is not limited to absorption; it covers a much wider range of phenomena. The authors hypothesize that different mechanisms produce the dissociation of persons with DID and DDNOS-1 as opposed to the dissociation of persons who do not have a dissociative disorder.

Construction of a Visible Diode Laser Source for Free Radical Photochemistry and Spectroscopy Experiments

NASA Technical Reports Server (NTRS)

Newman, Bronjelyn; Halpern, Joshua B.

1997-01-01

Tunable diode lasers are reliable sources of narrow-band light and comparatively cheap. Optical feedback simplifies frequency tuning of the laser diodes. We are building an inexpensive diode laser system incorporating optical feedback from a diffraction grating. The external optical cavity can be used with lasers that emit between 2 and 100 mW, and will also work if they are pulsed, although this will significantly degrade the bandwidth. The diode laser output power and bandwidth are comparable to CW dye lasers used in kinetics and dynamics experiments. However, their cost and maintenance will be much less as will alignment time. We intend to use the diode lasers to investigate CN and C2 kinetics as well as to study dissociation dynamics of atmospherically important molecules.

Mechanism of H adatoms improving the O2 reduction reaction on the Zn-modified anatase TiO2 (101) surface studied by first principles calculation.

PubMed

Liu, Liangliang; Li, Chongyang; Jiang, Man; Li, Xiaodong; Huang, Xiaowei; Wang, Zhu; Jia, Yu

2018-06-05

First principles calculations were performed to cast insight into the mechanism of the improvement of O2 reduction reaction (ORR) activity by Zn and H interstitials on the anatase TiO2 (101) surface. For the Zn-modified anatase TiO2 (101) surface, both surface and subsurface Zn interstitials could contribute to O2 adsorption and dissociation, but the dissociation barriers of O2 molecules are still too high, which limits the ORR activity. After a H adatom is introduced onto the Zn-modified anatase TiO2 (101) surface, the highest energy barriers are greatly reduced compared with those of the Zn-modified surface. Meanwhile, it is observed that the dissociation barriers decrease almost linearly with the increase of the charge difference of adsorption O2 between initial and transition state configurations. Specifically, subsurface Zn and surface H interstitials facilitate O2 dissociation and subsequent oxidation reactions, and further frequency analysis shows that these dissociation processes are frequent even at the room temperature of 300 K. In a word, this work provides a theoretical support to design a high ORR activity catalyst of the TiO2 nanocrystal comparable to precious Pt catalysts.

Mechanistic Study on Electronic Excitation Dissociation of the Cellobiose-Na+ Complex

NASA Astrophysics Data System (ADS)

Huang, Yiqun; Pu, Yi; Yu, Xiang; Costello, Catherine E.; Lin, Cheng

2016-02-01

The recent development of electron activated dissociation (ExD) techniques has opened the door for high-throughput, detailed glycan structural elucidation. Among them, ExD methods employing higher-energy electrons offer several advantages over low-energy electron capture dissociation (ECD), owing to their applicability towards chromophore-labeled glycans and singly charged ions, and ability to provide more extensive structural information. However, a lack of understanding of these processes has hindered rational optimization of the experimental conditions for more efficient fragmentation as well as the development of informatics tools for interpretation of the complex glycan ExD spectra. Here, cellobiose-Na+ was used as the model system to investigate the fragmentation behavior of metal-adducted glycans under irradiation of electrons with energy exceeding their ionization potential, and served as the basis on which a novel electronic excitation dissociation (EED) mechanism was proposed. It was found that ionization of the glycan produces a mixture of radical cations and ring-opened distonic ions. These distonic ions then capture a low-energy electron to produce diradicals with trivial singlet-triplet splitting, and subsequently undergo radical-induced dissociation to produce a variety of fragment ions, the abundances of which are influenced by the stability of the distonic ions from which they originate.

Electron-hole pair effects in methane dissociative chemisorption on Ni(111)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Xuan; Jiang, Bin, E-mail: bjiangch@ustc.edu.cn; Juaristi, J. Iñaki

The dissociative chemisorption of methane on metal surfaces has attracted much attention in recent years as a prototype of gas-surface reactions in understanding the mode specific and bond selective chemistry. In this work, we systematically investigate the influence of electron-hole pair excitations on the dissociative chemisorption of CH{sub 4}/CH{sub 3}D/CHD{sub 3} on Ni(111). The energy dissipation induced by surface electron-hole pair excitations is modeled as a friction force introduced in the generalized Langevin equation, in which the independent atomic friction coefficients are determined within the local-density friction approximation. Quasi-classical trajectory calculations for CH{sub 4}/CH{sub 3}D/CHD{sub 3} have been carried outmore » on a recently developed twelve-dimensional potential energy surface. Comparing the dissociation probabilities obtained with and without friction, our results clearly indicate that the electron-hole pair effects are generally small, both on absolute reactivity of each vibrational state and on the mode specificity and bond selectivity. Given similar observations in both water and methane dissociation processes, we conclude that electron-hole pair excitations would not play an important role as long as the reaction is direct and the interaction time between the molecule and metal electrons is relatively short.« less

Growth of Well-Aligned ZnO Nanorod Arrays and Their Application for Photovoltaic Devices

NASA Astrophysics Data System (ADS)

Yuan, Zhaolin; Yao, Juncai

2017-11-01

We have fabricated well-aligned ZnO nanorod arrays (ZNRAs) on indium tin oxide-coated glass substrates by a facile chemical bath deposition method. We used field-emission scanning electron microscope, x-ray diffraction and UV-Vis absorption spectroscopy to study the morphology, crystalline structure and optical absorption of the fabricated ZNRAs, respectively. The results showed that ZnO nanorods stood almost perpendicularly on the substrate, were about 30-50 nm in diameter and 800-900 nm in length, and were wurtzite-structured (hexagonal) ZnO. In addition, well-aligned ZNRAs exhibited a weak absorption in the visible region and had an optical band gap value of 3.28 eV. Furthermore, a hybrid ZNRAs/polymer photovoltaic device was made, under 1 sun AM 1.5 illumination (light intensity, ˜100 mW/cm2), and the device showed an open circuit voltage ( V oc) of 0.32 V, a short circuit current density ( J sc) of 7.67 mA/cm2, and a fill factor ( FF) of 0.37, yielding an overall power conversion efficiency of 0.91%. Also, the exciton dissociation and transportation processes of charge carriers in the device under illumination were explained according to its current density-voltage ( J- V) curve and the energy level diagram.

Dissociation of {sup 10}C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mamatkulov, K. Z.; Kattabekov, R. R.; Alikulov, S. S.

2013-10-15

The charge topology in the fragmentation of {sup 10}C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon is studied. In the coherent dissociation of {sup 10}C nuclei, about 82% of events are associated with the channel {sup 10}C {yields} 2{alpha}+ 2p. The angular distributions and correlations of product fragments are presented for this channel. It is found that among {sup 10}C {yields} 2{alpha}+ 2p events, about 30% are associated with the process in which dissociation through the ground state of the unstable {sup 9}Be{sub g.s.} nucleus is followed by {sup 8}Be{sub g.s.} + pmore » decays.« less

Change in heart rate variability after the adult attachment interview in dissociative patients.

PubMed

Farina, Benedetto; Speranza, Anna Maria; Imperatori, Claudio; Quintiliani, Maria Isabella; Della Marca, Giacomo

2015-01-01

The aim of this study was to assess heart rate variability (HRV) in individuals with dissociative disorders (DD) before and after the Adult Attachment Interview (AAI). Electrocardiograms were recorded before, during, and after the AAI in 13 individuals with DD and 13 healthy participants matched for age and gender. Significant change in HRV was observed only in the DD group. After the AAI, those with DD showed significant increases in the low frequency/high frequency ratio (pre-AAI = 1.91 ± 1.19; post-AAI = 4.03 ± 2.40; Wilcoxon test = -2.76, p = .005). Our results suggest that the retrieval of childhood attachment experiences in individuals with DD is associated with a change in HRV patterns that could reflect the emotion dysregulation of dissociative psychopathological processes.

The OI/1S/ state - Its quenching by O2 and formation by the dissociative recombination of vibrationally excited O2/+/ ions

NASA Technical Reports Server (NTRS)

Zipf, E. C.

1979-01-01

The rate coefficient for the quenching of metastable O(1S) atoms by O2 was measured as a function of temperature from 250 to 550 K. The resulting Arrhenius expression correlates well with previous laboratory work. It is suggested that the much larger value of the rate coefficient inferred from an analysis of artificial auroral experiment, Precede, may be explained by overestimation of the contribution of O(1S) production from O2(+) dissociative recombination. The possibility that O(1S) atoms are produced only by the dissociative recombination of vibrationally excited O2(+) ions is examined; such excited ions would not exist in the Precede experiment because of the rapid cooling of the ions by resonant charge transfer processes.

Déjà vecu for news events but not personal events: A dissociation between autobiographical and non-autobiographical episodic memory processing.

PubMed

Turner, Martha S; Shores, E Arthur; Breen, Nora; Coltheart, Max

2017-02-01

In déjà vu, the feeling that what we are currently experiencing we have experienced before is fleeting and is not accepted as true. In contrast, in déjà vecu or "recollective confabulation", the sense of déjà vu is persistent and convincing, and patients genuinely believe that they have lived through the current moment at some previous time. In previous reports of cases of déjà vecu, both personal events and non-personal, world events gave rise to this experience. In this paper we describe a patient whose déjà vecu experiences are entirely restricted to non-personal events, suggesting that autobiographical and non-autobiographical episodic memory processing can dissociate. We suggest that this dissociation is secondary to differences in the degree to which personal and emotional associations are formed for these two different types of event, and offer a two-factor theory of déjà vecu. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Study of acoustic fingerprinting of nitromethane and some triazole derivatives using UV 266 nm pulsed photoacoustic pyrolysis technique

NASA Astrophysics Data System (ADS)

Rao, K. S.; Chaudhary, A. K.; Yehya, F.; Kumar, A. Sudheer

2015-08-01

We report a comparative study of acoustic fingerprints of nitromethane, nitrobenzene and some nitro rich triazole derivatives using pulsed photoacoustic technique. UV 266 nm wavelength i.e. Fourth harmonic of Q-switched Nd: YAG laser having pulse duration 7 ns and 10 Hz repetition rate is employed to record the time resolved PA spectrum. The PA fingerprint is produced due to absorption of incident UV light by molecule itself and photo dissociation of nitromethane and nitrobenzene at room temperature while in case of triazole it is attributed to the combination of thermal and photo-dissociation process. The entire dissociation process follows the root of cleavage of C-NO2 bond to produce free NO, NO2 and other by product gases due to π∗ ← n excitation. In addition, we have studied the thermal stability criteria of nitro rich triazoles based on the quality factor of acoustic resonance frequencies of the PA cavity. We have also studied the effect of data acquisition time to ascertain the decay behavior of HEMs samples.

Study of acoustic fingerprinting of nitromethane and some triazole derivatives using UV 266 nm pulsed photoacoustic pyrolysis technique.

PubMed

Rao, K S; Chaudhary, A K; Yehya, F; Kumar, A Sudheer

2015-08-05

We report a comparative study of acoustic fingerprints of nitromethane, nitrobenzene and some nitro rich triazole derivatives using pulsed photoacoustic technique. UV 266 nm wavelength i.e. Fourth harmonic of Q-switched Nd: YAG laser having pulse duration 7 ns and 10 Hz repetition rate is employed to record the time resolved PA spectrum. The PA fingerprint is produced due to absorption of incident UV light by molecule itself and photo dissociation of nitromethane and nitrobenzene at room temperature while in case of triazole it is attributed to the combination of thermal and photo-dissociation process. The entire dissociation process follows the root of cleavage of C-NO₂ bond to produce free NO, NO₂ and other by product gases due to π(∗)←n excitation. In addition, we have studied the thermal stability criteria of nitro rich triazoles based on the quality factor of acoustic resonance frequencies of the PA cavity. We have also studied the effect of data acquisition time to ascertain the decay behavior of HEMs samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Eye tracking and pupillometry are indicators of dissociable latent decision processes.

PubMed

Cavanagh, James F; Wiecki, Thomas V; Kochar, Angad; Frank, Michael J

2014-08-01

Can you predict what people are going to do just by watching them? This is certainly difficult: it would require a clear mapping between observable indicators and unobservable cognitive states. In this report, we demonstrate how this is possible by monitoring eye gaze and pupil dilation, which predict dissociable biases during decision making. We quantified decision making using the drift diffusion model (DDM), which provides an algorithmic account of how evidence accumulation and response caution contribute to decisions through separate latent parameters of drift rate and decision threshold, respectively. We used a hierarchical Bayesian estimation approach to assess the single trial influence of observable physiological signals on these latent DDM parameters. Increased eye gaze dwell time specifically predicted an increased drift rate toward the fixated option, irrespective of the value of the option. In contrast, greater pupil dilation specifically predicted an increase in decision threshold during difficult decisions. These findings suggest that eye tracking and pupillometry reflect the operations of dissociated latent decision processes. PsycINFO Database Record (c) 2014 APA, all rights reserved.

"That part of the body is just gone": understanding and responding to dissociation and physical health.

PubMed

Haven, Terri J

2009-01-01

The past 2 decades have brought a significant surge in interest and research regarding the ways in which psychological trauma relates to the physical body. Researchers now understand a great deal about how the brain and the body process traumatic experiences, as well as the increased likelihood of an array of physical health consequences associated with both childhood and adult trauma and posttraumatic stress disorder. Experts are increasingly challenging mind-body dualism through solid theoretical and clinical bases for the central importance of listening to and communicating with trauma clients' bodies as part of reducing the suffering and long-lasting consequences of trauma. This article integrates this growing body of knowledge through a particular focus on trauma-induced dissociation and the implications of the physical and neurological processes and consequences of dissociation on clients' ability to participate in caring for their own bodies. The author utilizes an in-depth clinical example of expanding relational trauma psychotherapy to include a focus on working directly with trauma-related sensorimotor and physiological sensations and patterns.

Dissociation between morality and disgust: an event-related potential study.

PubMed

Yang, Qun; Li, An; Xiao, Xiao; Zhang, Ye; Tian, Xuehong

2014-10-01

This study explored the neural correlates of morality and disgust, particularly, how the mechanisms that mediate our avoidance of physically disgusting and morally abhorrent behaviors are neurologically dissociated during the time-course of processing. Twelve participants were asked to judge the acceptability of different types of behaviors, which varied in their level of moral wrongness and physical disgust, while event-related potentials (ERPs) were recorded. The main results showed that the two morally wrong conditions elicited greater amplitudes of P300-400 at frontal sites than the neutral condition and the physically disgusting, but not morally wrong, condition. The physically disgusting conditions (with and without moral content) elicited significantly more positive deflections in the 500-600 ms timeframe than the neutral condition at central-posterior sites. These findings indicate that our aversion to harmful substances in the physical environment and offensive behaviors in the social environment may be neurologically dissociable in the temporal dimension. Furthermore, the detection of moral violations may be processed earlier in time than that of physical disgust. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication of amplitude-phase type diffractive optical elements in aluminium films

NASA Astrophysics Data System (ADS)

Fomchenkov, S. A.; Butt, M. A.

2017-11-01

In the course of studies have been conducted a method of forming the phase diffractive optical elements (DOEs) by direct laser writing in thin films of aluminum. The quality of the aluminum films were investigated depending on the parameters of magnetron sputtering process. Moreover, the parameters of the laser writing process in thin films of aluminum were optimized. The structure of phase diffractive optical elements was obtained by the proposed method.

Protein-Protein Förster Resonance Energy Transfer Analysis of Nucleosome Core Particles Containing H2A and H2A.Z

PubMed Central

Hoch, Duane A.; Stratton, Jessica J.; Gloss, Lisa M.

2007-01-01

A protein-protein Förster resonance energy transfer (FRET) system, employing probes at multiple positions, was designed to specifically monitor the dissociation of the H2A-H2B dimer from the nucleosome core particle (NCP). Tryptophan donors and Cys-AEDANS acceptors were chosen because, in comparison to fluorophores used in previous NCP FRET studies, they: 1) are smaller and less hydrophobic which should minimize perturbations of histone and NCP structure; and 2) have an R0 of 20 Å, which is much less than the dimensions of the NCP (~50 Å width and ~100 Å diameter). CD and FL equilibrium protein unfolding titrations indicate that the donor and acceptor moieties have minimal effects on the stability of the H2A-H2B dimer and (H3-H4)2 tetramer. NCPs containing the various FRET pairs were reconstituted with the 601 artificial positioning DNA sequence. Equilibrium NaCl-induced dissociation of the modified NCPs showed that the 601 sequence stabilized the NCP to dimer dissociation as compared to previous studies using weaker positioning sequences. This finding implies a significant role for the H2A-H2B dimers in determining the DNA sequence dependence of NCP stability. The free energy of dissociation determined from reversible and well-defined sigmoidal transitions revealed two distinct phases reflecting the dissociation of each H2A-H2B dimer, confirming cooperativity in dimer dissociation. While cooperativity in the association/dissociation of the H2A-H2B dimers has been suggested previously, these data allow its quantitative description. The protein-protein FRET system was then used to study the effects of the histone variant H2A.Z on NCP stability; previous studies have reported both destabilizing and stabilizing effects. Comparison of the H2A and H2A.Z FRET NCP dissociation transitions suggest a slight increase in stability but a significant increase in cooperativity for dimer dissociation from H2A.Z NCPs. Thus, the utility of this protein-protein FRET system to monitor the effects of histone variants on NCP dynamics has been demonstrated, and the system appears equally well-suited for dissection of the kinetic processes of dimer association and dissociation from the NCP. PMID:17597150

The evolution of the deformation substructure in a Ni-Co-Cr equiatomic solid solution alloy

DOE PAGES

Miao, Jiashi; Slone, C. E.; Smith, T. M.; ...

2017-05-15

The equiatomic NiCoCr alloy exhibits an excellent combination of strength and ductility, even greater than the FeNiCrCoMn high entropy alloy, and also displays a simultaneous increase in strength and ductility with decreasing the testing temperature. To systemically investigate the origin of the exceptional properties of NiCoCr alloy, which are related to the evolution of the deformation substructure with strain, interrupted tensile testing was conducted on the equiatomic NiCoCr single-phase solid solution alloy at both cryogenic and room temperatures at five different plastic strain levels of 1.5%, 6.5%, 29%, 50% and 70%. The evolution of deformation substructure was examined using electronmore » backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), conventional transmission electron microscopy (CTEM), diffraction contrast imaging using STEM (DCI-STEM) and atomic resolution scanning transmission electron microscopy. While the deformation substructure mainly consisted of planar dislocation slip and the dissociation of dislocations into stacking faults at small strain levels (≤6.5%), at larger strain levels, additional substructures including nanotwins and a new phase with hexagonal close packed (HCP) lamellae also appeared. The volume fraction of the HCP lamellae increases with increasing deformation, especially at cryogenic temperature. First principles calculations at 0 K indicate that the HCP phase is indeed energetically favorable relative to FCC for this composition. In conclusion, the effects of the nanotwin and HCP lamellar structures on hardening rate and ductility at both cryogenic and room temperature are qualitatively discussed.« less

Brain oscillatory subsequent memory effects differ in power and long-range synchronization between semantic and survival processing.

PubMed

Fellner, Marie-Christin; Bäuml, Karl-Heinz T; Hanslmayr, Simon

2013-10-01

Memory crucially depends on the way information is processed during encoding. Differences in processes during encoding not only lead to differences in memory performance but also rely on different brain networks. Although these assumptions are corroborated by several previous fMRI and ERP studies, little is known about how brain oscillations dissociate between different memory encoding tasks. The present study therefore compared encoding related brain oscillatory activity elicited by two very efficient encoding tasks: a typical deep semantic item feature judgment task and a more elaborative survival encoding task. Subjects were asked to judge words either for survival relevance or for animacy, as indicated by a cue presented prior to the item. This allowed dissociating pre-item activity from item-related activity for both tasks. Replicating prior studies, survival processing led to higher recognition performance than semantic processing. Successful encoding in the semantic condition was reflected by a strong decrease in alpha and beta power, whereas successful encoding in the survival condition was related to increased alpha and beta long-range phase synchrony. Moreover, a pre-item subsequent memory effect in theta power was found which did not vary with encoding condition. These results show that measures of local synchrony (power) and global long range-synchrony (phase synchronization) dissociate between memory encoding processes. Whereas semantic encoding was reflected in decreases in local synchrony, increases in global long range synchrony were related to elaborative survival encoding, presumably reflecting the involvement of a more widespread cortical network in this task. Copyright © 2013 Elsevier Inc. All rights reserved.

High-Pressure-Driven Reversible Dissociation of α-Synuclein Fibrils Reveals Structural Hierarchy.

PubMed

Piccirilli, Federica; Plotegher, Nicoletta; Ortore, Maria Grazia; Tessari, Isabella; Brucale, Marco; Spinozzi, Francesco; Beltramini, Mariano; Mariani, Paolo; Militello, Valeria; Lupi, Stefano; Perucchi, Andrea; Bubacco, Luigi

2017-10-17

The analysis of the α-synuclein (aS) aggregation process, which is involved in Parkinson's disease etiopathogenesis, and of the structural feature of the resulting amyloid fibrils may shed light on the relationship between the structure of aS aggregates and their toxicity. This may be considered a paradigm of the ground work needed to tackle the molecular basis of all the protein-aggregation-related diseases. With this aim, we used chemical and physical dissociation methods to explore the structural organization of wild-type aS fibrils. High pressure (in the kbar range) and alkaline pH were used to disassemble fibrils to collect information on the hierarchic pathway by which distinct β-sheets sequentially unfold using the unique possibility offered by high-pressure Fourier transform infrared spectroscopy. The results point toward the formation of kinetic traps in the energy landscape of aS fibril disassembly and the presence of transient partially folded species during the process. Since we found that the dissociation of wild-type aS fibrils by high pressure is reversible upon pressure release, the disassembled molecules likely retain structural information that favors fibril reformation. To deconstruct the role of the different regions of aS sequence in this process, we measured the high-pressure dissociation of amyloids formed by covalent chimeric dimers of aS (syn-syn) and by the aS deletion mutant that lacks the C-terminus, i.e., aS (1-99). The results allowed us to single out the role of dimerization and that of the C-terminus in the complete maturation of fibrillar aS. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors

PubMed Central

Thorman, Rachel M; Kumar T. P., Ragesh; Fairbrother, D Howard

2015-01-01

Summary Focused electron beam induced deposition (FEBID) is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (<100 eV) secondary electrons generated by interactions of the primary beam with the substrate. These low-energy electrons are abundant both inside and outside the area of the primary electron beam and are associated with reactions causing incomplete ligand dissociation from FEBID precursors. As it is not possible to directly study the effects of secondary electrons in situ in FEBID, other means must be used to elucidate their role. In this context, gas phase studies can obtain well-resolved information on low-energy electron-induced reactions with FEBID precursors by studying isolated molecules interacting with single electrons of well-defined energy. In contrast, ultra-high vacuum surface studies on adsorbed precursor molecules can provide information on surface speciation and identify species desorbing from a substrate during electron irradiation under conditions more representative of FEBID. Comparing gas phase and surface science studies allows for insight into the primary deposition mechanisms for individual precursors; ideally, this information can be used to design future FEBID precursors and optimize deposition conditions. In this review, we give a summary of different low-energy electron-induced fragmentation processes that can be initiated by the secondary electrons generated in FEBID, specifically, dissociative electron attachment, dissociative ionization, neutral dissociation, and dipolar dissociation, emphasizing the different nature and energy dependence of each process. We then explore the value of studying these processes through comparative gas phase and surface studies for four commonly-used FEBID precursors: MeCpPtMe3, Pt(PF3)4, Co(CO)3NO, and W(CO)6. Through these case studies, it is evident that this combination of studies can provide valuable insight into potential mechanisms governing deposit formation in FEBID. Although further experiments and new approaches are needed, these studies are an important stepping-stone toward better understanding the fundamental physics behind the deposition process and establishing design criteria for optimized FEBID precursors. PMID:26665061

The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors.

PubMed

Thorman, Rachel M; Kumar T P, Ragesh; Fairbrother, D Howard; Ingólfsson, Oddur

2015-01-01

Focused electron beam induced deposition (FEBID) is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (<100 eV) secondary electrons generated by interactions of the primary beam with the substrate. These low-energy electrons are abundant both inside and outside the area of the primary electron beam and are associated with reactions causing incomplete ligand dissociation from FEBID precursors. As it is not possible to directly study the effects of secondary electrons in situ in FEBID, other means must be used to elucidate their role. In this context, gas phase studies can obtain well-resolved information on low-energy electron-induced reactions with FEBID precursors by studying isolated molecules interacting with single electrons of well-defined energy. In contrast, ultra-high vacuum surface studies on adsorbed precursor molecules can provide information on surface speciation and identify species desorbing from a substrate during electron irradiation under conditions more representative of FEBID. Comparing gas phase and surface science studies allows for insight into the primary deposition mechanisms for individual precursors; ideally, this information can be used to design future FEBID precursors and optimize deposition conditions. In this review, we give a summary of different low-energy electron-induced fragmentation processes that can be initiated by the secondary electrons generated in FEBID, specifically, dissociative electron attachment, dissociative ionization, neutral dissociation, and dipolar dissociation, emphasizing the different nature and energy dependence of each process. We then explore the value of studying these processes through comparative gas phase and surface studies for four commonly-used FEBID precursors: MeCpPtMe3, Pt(PF3)4, Co(CO)3NO, and W(CO)6. Through these case studies, it is evident that this combination of studies can provide valuable insight into potential mechanisms governing deposit formation in FEBID. Although further experiments and new approaches are needed, these studies are an important stepping-stone toward better understanding the fundamental physics behind the deposition process and establishing design criteria for optimized FEBID precursors.

Dissociable Stages of Problem Solving (II): First Evidence for Process-Contingent Temporal Order of Activation in Dorsolateral Prefrontal Cortex

ERIC Educational Resources Information Center

Ruh, Nina; Rahm, Benjamin; Unterrainer, Josef M.; Weiller, Cornelius; Kaller, Christoph P.

2012-01-01

In a companion study, eye-movement analyses in the Tower of London task (TOL) revealed independent indicators of functionally separable cognitive processes during problem solving, with processes of building up an internal representation of the problem preceding actual planning processes. These results imply that processes of internalization and…

Processing and error compensation of diffractive optical element

NASA Astrophysics Data System (ADS)

Zhang, Yunlong; Wang, Zhibin; Zhang, Feng; Qin, Hui; Li, Junqi; Mai, Yuying

2014-09-01

Diffractive optical element (DOE) shows high diffraction efficiency and good dispersion performance, which makes the optical system becoming light-weight and more miniature. In this paper, the design, processing, testing, compensation of DOE are discussed, especially the analyzing of compensation technology which based on the analyzing the DOE measurement date from Taylor Hobson PGI 1250. In this method, the relationship between shadowing effect with diamond tool and processing accuracy are analyzed. According to verification processing on the Taylor Hobson NANOFORM 250 lathe, the results indicate that the PV reaches 0.539 micron, the surface roughness reaches 4nm, the step position error is smaller than λ /10 and the step height error is less than 0.23 micron after compensation processing one time.

PREFACE: Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications

NASA Astrophysics Data System (ADS)

Wolf, Andreas; Lammich, Lutz; Schmelcher, Peter

2005-01-01

Dissociative recombination between electrons and molecular ions is an elementary reaction in electron-induced chemistry attracting strong attention across discipline boundaries, from fundamental questions of intramolecular dynamics to astrophysics, plasma science, as well as atmospheric and planetary physics. The process is explored on the level of atomic quantum dynamics both experimentally and theoretically, employing cold collisions at temperatures down to 10 Kelvin involving small molecules or also very large systems ranging up to biomolecules. Dissociative recombination (DR) and related processes, such as dissociative excitation, collisional cooling of vibrations and rotations, photodissociation via high-lying electronic states, resonant electron attachment, and electron-induced processes in large molecules and clusters, are studied by a variety of experimental methods, including stored and trapped molecular ions, plasma techniques such as stationary and flowing afterglow, and laser spectroscopic diagnostic of molecular excitations. The Sixth International Conference on Dissociative Recombination: Theory, Experiments and Applications (DR2004) was organized by the Research Group on Atomic and Molecular Physics with Stored Ions at the Max-Planck Institute for Nuclear Physics in Heidelberg, Germany, and held near Heidelberg in the town of Mosbach in July 2004. It was attended by about 90 scientists working in atomic and molecular physics, astrophysics, plasma- and biophysics. International Conferences on Dissociative Recombination and related processes were held before at Lake Louise, Alberta, Canada (1988), Saint Jacut, Brittany, France (1992), Ein Gedi, Israel (1995), Nässlingen, Stockholm Archipelago, Sweden (1999), and last within a symposium at the American Chemical Society meeting in Chicago, USA (2001). The presentations of this conference document a strong development of theoretical ideas towards the understanding of DR in particular in polyatomic systems. Strong attention was given to the elementary triatomic benchmark system H3+, characterized by ambitious, complementary experimental projects. Interaction of experiment and theory improves in particular the understanding of non-adiabatic molecular interactions involving electronic continuum states. New experimental techniques focus on a detailed control of the internal molecular excitation on the level of single quantum states, which gives increasing importance to laser interactions and ion storage at cryogenic temperatures. Apart from its place in the series of "DR conferences", this meeting is also the final assembly of the EU Research Training Network "Electron Transfer Reactions" (ETR) which in the period from 2000 to 2004 helped to establish many invaluable links between 15 experimental and theoretical institutes active in the field of DR and related processes. We express our gratitude to the EU for the support through the Research Training Network Programme, which has made possible the attendance of many students and young researchers. Furthermore, generous financial support for this conference was provided by the Max-Planck Institute for Nuclear Physics in Heidelberg. The efficient support of the conference center "Alte Mälzerei", operated by the city of Mosbach, is gratefully acknowledged. Finally we warmly thank the staff and the students of the Max-Planck Institute for Nuclear Physics for the dedicated help during the conference.

Task-related modulation of effective connectivity during perceptual decision making: dissociation between dorsal and ventral prefrontal cortex.

PubMed

Akaishi, Rei; Ueda, Naoko; Sakai, Katsuyuki

2013-01-01

The dorsal and ventral parts of the lateral prefrontal cortex have been thought to play distinct roles in decision making. Although its dorsal part such as the frontal eye field (FEF) is shown to play roles in accumulation of sensory information during perceptual decision making, the role of the ventral prefrontal cortex (PFv) is not well-documented. Previous studies have suggested that the PFv is involved in selective attention to the task-relevant information and is associated with accuracy of the behavioral performance. It is unknown, however, whether the accumulation and selection processes are anatomically dissociated between the FEF and PFv. Here we show that, by using concurrent TMS and EEG recording, the short-latency (20-40 ms) TMS-evoked potentials after stimulation of the FEF change as a function of the time to behavioral response, whereas those after stimulation of the PFv change depending on whether the response is correct or not. The potentials after stimulation of either region did not show significant interaction between time to response and performance accuracy, suggesting dissociation between the processes subserved by the FEF and PFv networks. The results are consistent with the idea that the network involving the FEF plays a role in information accumulation, whereas the network involving the PFv plays a role in selecting task relevant information. In addition, stimulation of the FEF and PFv induced activation in common regions in the dorsolateral and medial frontal cortices, suggesting convergence of information processed in the two regions. Taken together, the results suggest dissociation between the FEF and PFv networks for their computational roles in perceptual decision making. The study also highlights the advantage of TMS-EEG technique in investigating the computational processes subserved by the neural network in the human brain with a high temporal resolution.

Investigation on the Oxidation and Reduction of Titanium in Molten Salt with the Soluble TiC Anode

NASA Astrophysics Data System (ADS)

Wang, Shulan; Wan, Chaopin; Liu, Xuan; Li, Li

2015-12-01

To reveal the oxidation process of titanium from TiC anode and the reduction mechanism of titanium ions in molten NaCl-KCl, the polarization curve of TiC anode in molten NaCl-KCl and cyclic voltammograms of the molten salt after polarization were studied. Investigation on the polarization curve shows that titanium can be oxidized and dissociated from the TiC anode at very low potential. The cyclic voltammograms demonstrated that the reduction reaction of titanium ions in the molten salt is a one-step process. By potentiostatic electrolysis, dendritic titanium is obtained on the steel plate. The work promotes the understanding on the process of electrochemical oxidization/dissociation of titanium from TiC anode and the reduction mechanism of titanium ions in molten salt.

Construction of a coarse-grain quasi-classical trajectory method. II. Comparison against the direct molecular simulation method

NASA Astrophysics Data System (ADS)

Macdonald, R. L.; Grover, M. S.; Schwartzentruber, T. E.; Panesi, M.

2018-02-01

This work presents the analysis of non-equilibrium energy transfer and dissociation of nitrogen molecules (N2(g+1Σ) ) using two different approaches: the direct molecular simulation (DMS) method and the coarse-grain quasi-classical trajectory (CG-QCT) method. The two methods are used to study thermochemical relaxation in a zero-dimensional isochoric and isothermal reactor in which the nitrogen molecules are heated to several thousand degrees Kelvin, forcing the system into strong non-equilibrium. The analysis considers thermochemical relaxation for temperatures ranging from 10 000 to 25 000 K. Both methods make use of the same potential energy surface for the N2(g+1Σ ) -N2(g+1Σ ) system taken from the NASA Ames quantum chemistry database. Within the CG-QCT method, the rovibrational energy levels of the electronic ground state of the nitrogen molecule are lumped into a reduced number of bins. Two different grouping strategies are used: the more conventional vibrational-based grouping, widely used in the literature, and energy-based grouping. The analysis of both the internal state populations and concentration profiles show excellent agreement between the energy-based grouping and the DMS solutions. During the energy transfer process, discrepancies arise between the energy-based grouping and DMS solution due to the increased importance of mode separation for low energy states. By contrast, the vibrational grouping, traditionally considered state-of-the-art, captures well the behavior of the energy relaxation but fails to consistently predict the dissociation process. The deficiency of the vibrational grouping model is due to the assumption of strict mode separation and equilibrium of rotational energy states. These assumptions result in errors predicting the energy contribution to dissociation from the rotational and vibrational modes, with rotational energy actually contributing 30%-40% of the energy required to dissociate a molecule. This work confirms the findings discussed in Paper I [R. L. Macdonald et al., J. Chem. Phys. 148, 054309 (2018)], which underlines the importance of rotational energy to the dissociation process, and demonstrates that an accurate non-equilibrium chemistry model must accurately predict the deviation of rovibrational distribution from equilibrium.

Construction of a coarse-grain quasi-classical trajectory method. II. Comparison against the direct molecular simulation method.

PubMed

Macdonald, R L; Grover, M S; Schwartzentruber, T E; Panesi, M

2018-02-07

This work presents the analysis of non-equilibrium energy transfer and dissociation of nitrogen molecules (N 2 (Σg+1)) using two different approaches: the direct molecular simulation (DMS) method and the coarse-grain quasi-classical trajectory (CG-QCT) method. The two methods are used to study thermochemical relaxation in a zero-dimensional isochoric and isothermal reactor in which the nitrogen molecules are heated to several thousand degrees Kelvin, forcing the system into strong non-equilibrium. The analysis considers thermochemical relaxation for temperatures ranging from 10 000 to 25 000 K. Both methods make use of the same potential energy surface for the N 2 (Σg+1)-N 2 (Σg+1) system taken from the NASA Ames quantum chemistry database. Within the CG-QCT method, the rovibrational energy levels of the electronic ground state of the nitrogen molecule are lumped into a reduced number of bins. Two different grouping strategies are used: the more conventional vibrational-based grouping, widely used in the literature, and energy-based grouping. The analysis of both the internal state populations and concentration profiles show excellent agreement between the energy-based grouping and the DMS solutions. During the energy transfer process, discrepancies arise between the energy-based grouping and DMS solution due to the increased importance of mode separation for low energy states. By contrast, the vibrational grouping, traditionally considered state-of-the-art, captures well the behavior of the energy relaxation but fails to consistently predict the dissociation process. The deficiency of the vibrational grouping model is due to the assumption of strict mode separation and equilibrium of rotational energy states. These assumptions result in errors predicting the energy contribution to dissociation from the rotational and vibrational modes, with rotational energy actually contributing 30%-40% of the energy required to dissociate a molecule. This work confirms the findings discussed in Paper I [R. L. Macdonald et al., J. Chem. Phys. 148, 054309 (2018)], which underlines the importance of rotational energy to the dissociation process, and demonstrates that an accurate non-equilibrium chemistry model must accurately predict the deviation of rovibrational distribution from equilibrium.

Dissociative Ionization of Aromatic and Heterocyclic Molecules

NASA Technical Reports Server (NTRS)

Huo, Winifred M.

2003-01-01

Space radiation poses a major health hazard to humans in space flight. The high-energy charged particles in space radiation ranging from protons to high atomic number, high-energy (HZE) particles, and the secondary species they produce, attack DNA, cells, and tissues. Of the potential hazards, long-term health effects such as carcinogenesis are likely linked to the DNA lesions caused by secondary electrons in the 1 - 30 eV range. Dissociative ionization (DI) is one of the electron collision processes that can damage the DNA, either directly by causing a DNA lesion, or indirectly by producing radicals and cations that attack the DNA. To understand this process, we have developed a theoretical model for DI. Our model makes use of the fact that electron motion is much faster than nuclear motion and assumes DI proceeds through a two-step process. The first step is electron-impact ionization resulting in a particular state of the molecular ion in the geometry of the neutral molecule. In the second step the ion undergoes unimolecular dissociation. Thus the DI cross section sigma(sup DI)(sub a) for channel a is given by sigma(sup DI)(sub a) = sigma(sup I)(sub a) P(sub D) with sigma(sup I)(sub a) the ionization cross section of channel a and P(sub D) the dissociation probability. This model has been applied to study the DI of H2O, NH3, and CH4, with results in good agreement with experiment. The ionization cross section sigma(sup I)(sub a) was calculated using the improved binary encounter-dipole model and the unimolecular dissociation probability P(sub D) obtained by following the minimum energy path determined by the gradients and Hessians of the electronic energy with respect to the nuclear coordinates of the ion. This model is used to study the DI from the low-lying channels of benzene and pyridine to understand the different product formation in aromatic and heterocyclic molecules. DI study of the DNA base thymine is underway. Solvent effects will also be discussed.

Applications of density functional theory calculations to selected problems in hydrocarbon processing

NASA Astrophysics Data System (ADS)

Nabar, Rahul

Recent advances in theoretical techniques and computational hardware have made it possible to apply Density Functional Theory (DFT) methods to realistic problems in heterogeneous catalysis. Hydrocarbon processing is economically, and strategically, a very important industrial sector in today's world. In this thesis, we employ DFT methods to examine several important problems in hydrocarbon processing. Fischer Tropsch Synthesis (FTS) is a mature technology to convert synthesis gas derived from coal, natural-gas or biomass into liquid fuels, specifically diesel. Iron is an active FTS catalyst, but the absence of detailed reaction mechanisms make it difficult to maximize activity and optimize product distribution. We evaluate thermochemistry, kinetics and Rate Determining Steps (RDS) for Fischer Tropsch Synthesis on several models of Fe catalysts: Fe(110), Fe(211) and Pt promoted Fe(110). Our studies indicated that CO-dissociation is likely to be the RDS under most reaction conditions, but the DFT-calculated activation energy ( Ea) for direct CO dissociation was too large to explain the observed catalyst activity. Consequently we demonstrate that H-assisted CO-dissociation pathways are competitive with direct CO dissociation on both Co and Fe catalysts and could be responsible for a major fraction of the reaction flux (especially at high CO coverages). We then extend this alternative mechanistic model to closed-packed facets of nine transition metal catalysts (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt). H-assisted CO dissociation offers a kinetically easier route on each of the metals studied. DFT methods are also applied to another problem from the petroleum industry: discovery of poison-resistant, bimetallic, alloy catalysts (poisons: C, S, CI, P). Our systematic screening studies identify several Near Surface Alloys (NSAs) that are expected to be highly poison-resistant yet stable and avoiding adsorbate induced reconstruction. Adsorption trends are also correlated with electronic structure. Eventually we extend this work to compile a database of Binding Energies for 17 adsorbates of catalytic interest on a set of 17 transition metals and their NSAs. Practical examples of how such a database, in conjunction with screening criteria, can be fruitfully utilized for rational catalyst design, are also provided.

CO2 Dissociation using the Versatile Atmospheric Dielectric Barrier Discharge Experiment (VADER)

NASA Astrophysics Data System (ADS)

Lindon, Michael Allen

As of 2013, the Carbon Dioxide Information Analysis Center (CDIAC) estimates that the world emits approximately 36 trillion metric tons of Carbon Dioxide (CO2) into the atmosphere every year. These large emissions have been correlated to global warming trends that have many consequences across the globe, including glacial retraction, ocean acidification and increased severity of weather events. With green technologies still in the infancy stage, it can be expected that CO2 emissions will stay this way for along time to come. Approximately 41% of the emissions are due to electricity production, which pump out condensed forms of CO2. This danger to our world is why research towards new and innovative ways of controlling CO2 emissions from these large sources is necessary. As of now, research is focused on two primary methods of CO2 reduction from condensed CO2 emission sources (like fossil fuel power plants): Carbon Capture and Sequestration (CCS) and Carbon Capture and Utilization (CCU). CCS is the process of collecting CO2 using absorbers or chemicals, extracting the gas from those absorbers and finally pumping the gas into reservoirs. CCU on the other hand, is the process of reacting CO2 to form value added chemicals, which can then be recycled or stored chemically. A Dielectric Barrier discharge (DBD) is a pulsed, low temperature, non-thermal, atmospheric pressure plasma which creates high energy electrons suitable for dissociating CO2 into its components (CO and O) as one step in the CCU process. Here I discuss the viability of using a DBD for CO2 dissociation on an industrial scale as well as the fundamental physics and chemistry of a DBD for CO2 dissociation. This work involved modeling the DBD discharge and chemistry, which showed that there are specific chemical pathways and plasma parameters that can be adjusted to improve the CO2 reaction efficiencies and rates. Experimental studies using the Versatile Atmospheric dielectric barrier Discharge ExpeRiment (VADER) demonstrated how different factors, like voltage, frequency and the addition of a photocatalyst, change the efficiency of CO2 dissociation in VADER and the plasma chemistry involved.

Phase stability of iron germanate, FeGeO 3, to 127 GPa

DOE PAGES

Dutta, R.; Tracy, S. J.; Stan, C. V.; ...

2017-11-15

The high-pressure behavior of germanates is of interest as these compounds serve as analogs for silicates of the deep Earth. Current theoretical and experimental studies of iron germanate, FeGeO 3, are limited. Here in this paper, we have examined the behavior of FeGeO 3 to 127 GPa using the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. Upon compression at room temperature, the ambient-pressure clinopyroxene phase transforms to a disordered triclinic phase [FeGeO 3 (II)] at ~ 18 GPa in agreement with earlier studies. An additional phase transition to FeGeO 3 (III) occurs above 54 GPa atmore » room temperature. Laser-heating experiments (~ 1200–2200 K) were conducted at three pressures (33, 54, and 123 GPa) chosen to cover the stability regions of different GeO 2 polymorphs. In all cases, we observe that FeGeO 3 dissociates into GeO 2 + FeO at high pressure and temperature conditions. Neither the perovskite nor the post-perovskite phase was observed up to 127 GPa at ambient or high temperatures. The results are consistent with the behavior of FeSiO 3, which also dissociates into a mixture of the oxides (FeO + SiO 2) at least up to 149 GPa.« less

High-resolution crystal structure of Streptococcus pyogenes β-NAD⁺ glycohydrolase in complex with its endogenous inhibitor IFS reveals a highly water-rich interface.

PubMed

Yoon, Ji Young; An, Doo Ri; Yoon, Hye Jin; Kim, Hyoun Sook; Lee, Sang Jae; Im, Ha Na; Jang, Jun Young; Suh, Se Won

2013-11-01

One of the virulence factors produced by Streptococcus pyogenes is β-NAD(+) glycohydrolase (SPN). S. pyogenes injects SPN into the cytosol of an infected host cell using the cytolysin-mediated translocation pathway. As SPN is toxic to bacterial cells themselves, S. pyogenes possesses the ifs gene that encodes an endogenous inhibitor for SPN (IFS). IFS is localized intracellularly and forms a complex with SPN. This intracellular complex must be dissociated during export through the cell envelope. To provide a structural basis for understanding the interactions between SPN and IFS, the complex was overexpressed between the mature SPN (residues 38-451) and the full-length IFS (residues 1-161), but it could not be crystallized. Therefore, limited proteolysis was used to isolate a crystallizable SPNct-IFS complex, which consists of the SPN C-terminal domain (SPNct; residues 193-451) and the full-length IFS. Its crystal structure has been determined by single anomalous diffraction and the model refined at 1.70 Å resolution. Interestingly, our high-resolution structure of the complex reveals that the interface between SPNct and IFS is highly rich in water molecules and many of the interactions are water-mediated. The wet interface may facilitate the dissociation of the complex for translocation across the cell envelope.

Impact of pentacene film thickness on the photoresponse spectra: Determination of the photocarrier generation mechanism

NASA Astrophysics Data System (ADS)

Gorgolis, S.; Giannopoulou, A.; Anastassopoulos, D.; Kounavis, P.

2012-07-01

Photocurrent response, optical absorption, and x-ray diffraction (XRD) measurements in pentacene films grown on glass substrates are performed in order to obtain an insight into the mobile photocarriers generation mechanism. For film thickness of the order of 50 nm and lower, the photocurrent response spectra are found to follow the optical absorption spectra demonstrating the so-called symbatic response. Upon increasing the film thickness, the photoresponse demonstrates a transition to the so-called antibatic response, which is characterized by a maximum and minimum photocurrent for photon energies of minimum and maximum optical absorption, respectively. The experimental results are not in accordance with the model of important surface recombination rate. By taking into account the XRD patterns, the experimental photoresponse spectra can be reproduced by model simulations assuming efficient exciton dissociation at a narrow layer of the order of 20 nm near the pentacene-substrate interface. The simulated spectra are found sensitive to the film thickness, the absolute optical absorption coefficient, and the diffusion exciton length. By comparing the experimental with the simulated spectra, it is deduced that the excitons, which are created by optical excitation in the spectral region of 1.7-2.2 eV, diffuse with a diffusion length of the order of 10-80 nm to the pentacene-substrate interface where efficiently dissociate into mobile charge carriers.

Childhood trauma and eating psychopathology: a mediating role for dissociation and emotion dysregulation?

PubMed

Moulton, Stuart J; Newman, Emily; Power, Kevin; Swanson, Vivien; Day, Kenny

2015-01-01

The present study examined the relationship between different forms of childhood trauma and eating psychopathology using a multiple mediation model that included emotion dysregulation and dissociation as hypothesised mediators. 142 female undergraduate psychology students studying at two British Universities participated in this cross-sectional study. Participants completed measures of childhood trauma (emotional abuse, physical abuse, sexual abuse, emotional neglect and physical neglect), eating psychopathology, dissociation and emotion dysregulation. Multiple mediation analysis was conducted to investigate the study's proposed model. Results revealed that the multiple mediation model significantly predicted eating psychopathology. Additionally, both emotion dysregulation and dissociation were found to be significant mediators between childhood trauma and eating psychopathology. A specific indirect effect was observed between childhood emotional abuse and eating psychopathology through emotion dysregulation. Findings support previous research linking childhood trauma to eating psychopathology. They indicate that multiple forms of childhood trauma should be assessed for individuals with eating disorders. The possible maintaining role of emotion regulation processes should also be considered in the treatment of eating disorders. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamics of Singlet Fission and Electron Injection in Self-Assembled Acene Monolayers on Titanium Dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Justin C; Pace, Natalie A; Arias, Dylan H

We employ a combination of linear spectroscopy, electrochemistry, and transient absorption spectroscopy to characterize the interplay between electron transfer and singlet fission dynamics in polyacene-based dyes attached to nanostructured TiO2. For triisopropyl silylethynyl (TIPS)-pentacene, we find that the singlet fission time constant increases to 6.5 ps on a nanostructured TiO2 surface relative to a thin film time constant of 150 fs, and that triplets do not dissociate after they are formed. In contrast, TIPS-tetracene singlets quickly dissociate in 2 ps at the molecule/TiO2 interface, and this dissociation outcompetes the relatively slow singlet fission process. The addition of an alumina layermore » slows down electron injection, allowing the formation of triplets from singlet fission in 40 ps. However, the triplets do not inject electrons, which is likely due to a lack of sufficient driving force for triplet dissociation. These results point to the critical balance required between efficient singlet fission and appropriate energetics for interfacial charge transfer.« less

Entropic-elasticity-controlled dissociation and energetic-elasticity-controlled rupture induce catch-to-slip bonds in cell-adhesion molecules.

PubMed

Wei, YuJie

2008-03-01

We develop a physical model to describe the kinetic behavior in cell-adhesion molecules. Unbinding of noncovalent biological bonds is assumed to occur by both bond dissociation and bond rupture. Such a decomposition of debonding processes is a space decomposition of the debonding events. Dissociation under thermal fluctuation is nondirectional in a three-dimensional space, and its energy barrier to escape is not influenced by a tensile force, but the microstates that could lead to dissociation are changed by the tensile force; rupture happens along the tensile force direction. An applied force effectively lowers the energy barrier to escape along the loading direction. The lifetime of the biological bond, due to the two concurrent off rates, may grow with increasing tensile force to a moderate amount and then decrease with further increasing load. We hypothesize that a catch-to-slip bond transition is a generic feature in biological bonds. The model also predicts that catch bonds in a more flexible molecular structure have longer lifetimes and need less force to be fully activated.

Communication: Direct evidence for sequential dissociation of gas-phase Fe(CO)5 via a singlet pathway upon excitation at 266 nm

PubMed Central

Leitner, T.; Mazza, T.; Schröder, H.; Kunnus, K.; Schreck, S.; Radcliffe, P.; Düsterer, S.; Meyer, M.; Föhlisch, A.

2017-01-01

We prove the hitherto hypothesized sequential dissociation of Fe(CO)5 in the gas phase upon photoexcitation at 266 nm via a singlet pathway with time-resolved valence and core-level photoelectron spectroscopy with an x-ray free-electron laser. Valence photoelectron spectra are used to identify free CO molecules and to determine the time constants of stepwise dissociation to Fe(CO)4 within the temporal resolution of the experiment and further to Fe(CO)3 within 3 ps. Fe 3p core-level photoelectron spectra directly reflect the singlet spin state of the Fe center in Fe(CO)5, Fe(CO)4, and Fe(CO)3 showing that the dissociation exclusively occurs along a singlet pathway without triplet-state contribution. Our results are important for assessing intra- and intermolecular relaxation processes in the photodissociation dynamics of the prototypical Fe(CO)5 complex in the gas phase and in solution, and they establish time-resolved core-level photoelectron spectroscopy as a powerful tool for determining the multiplicity of transition metals in photochemical reactions of coordination complexes. PMID:28595420

Cognition and belief in paranormal phenomena: gestalt/feature-intensive processing theory and tendencies toward ADHD, depression, and dissociation.

PubMed

Sharps, Matthew J; Matthews, Justin; Asten, Janet

2006-11-01

Belief in paranormal phenomena and cryptids--unknown animals such as Bigfoot--may predispose individuals to interpret real-world objects and events in the same way that eyewitness identification can be biased by unrelated information (P. James and N. Thorpe, 1999). Psychological tendencies toward attention deficit hyperactivity disorder (ADHD), dissociation, and depression, even at subclinical levels, may be associated systematically with particular paranormal or cryptozoological beliefs. The authors evaluated these psychological tendencies using the Conners Adult ADHD Rating Scales (C. K. Conners, D. Erhardt, and E. Sparrow, 1999), the Dissociative Experiences Scale (L. Coleman & J. Clark, 1999), and the Beck Depression Inventory-II (A. T. Beck, 1996). They performed regression analyses against beliefs in ghosts, unidentified flying objects (UFOs), extrasensory perception (ESP), astrology, and cryptids. ADHD, dissociation, and depression were associated with enhanced tendencies toward paranormal and cryptozoological beliefs, although participants who believed in each of the phenomena differed from one another in predictable and psychologically distinguishable ways. Cognitively biasing influences of preexisting psychological tendencies may predispose individuals to specific perceptual and cognitive errors during confrontation of real-world phenomena.

Theoretical studies of association and dissociation of Feshbach molecules in a microgravity environment

NASA Astrophysics Data System (ADS)

D'Incao, Jose; Williams, Jason

2017-04-01

NASA's Cold Atom Laboratory (CAL) is a multi-user facility scheduled for launch to the ISS in 2017. Our flight experiments with CAL will characterize and mitigate leading-order systematics in dual-atomic-species atom interferometers in microgravity relevant for future fundamental physics missions in space. As part of the initial state preparation for interferometry studies, here, we study the RF association and dissociation of weakly bound heteronuclear Feshbach molecules for expected parameters relevant for the microgravity environment of CAL. This includes temperatures on the pico-Kelvin range and atomic densities as low as 108/cm3. We show that under such conditions, thermal and loss effects can be greatly suppressed, resulting in high efficiency in both association and dissociation of extremely weakly bound Feshbach molecules and allowing for high accuracy determination coherent properties of such processes. In addition we study the possibility to implement delta-kick cooling techniques for weakly bound heteronuclear molecules and explore numerically other methods for molecular association and dissociation including the effects of three-body interactions. This research is supported by the National Aeronautics and Space Administration.

A thermal extrapolation method for the effective temperatures and internal energies of activated ions

NASA Astrophysics Data System (ADS)

Meot-Ner (Mautner), Michael; Somogyi, Árpád

2007-11-01

The internal energies of dissociating ions, activated chemically or collisionally, can be estimated using the kinetics of thermal dissociation. The thermal Arrhenius parameters can be combined with the observed dissociation rate of the activated ions using kdiss = Athermalexp(-Ea,thermal/RTeff). This Arrhenius-type relation yields the effective temperature, Teff, at which the ions would dissociate thermally at the same rate, or yield the same product distributions, as the activated ions. In turn, Teff is used to calculate the internal energy of the ions and the energy deposited by the activation process. The method yields an energy deposition efficiency of 10% for a chemical ionization proton transfer reaction and 8-26% for the surface collisions of various peptide ions. Internal energies of ions activated by chemical ionization or by gas phase collisions, and of ions produced by desorption methods such as fast atom bombardment, can be also evaluated. Thermal extrapolation is especially useful for ion-molecule reaction products and for biological ions, where other methods to evaluate internal energies are laborious or unavailable.

UV-Vis spectrophotometric studies of self-oxidation/dissociation of quaternary ammonium permanganates (QAP) - impact of solvent polarity

NASA Astrophysics Data System (ADS)

Bank, Suraj Prakash; Guru, Partha Sarathi; Dash, Sukalyan

2015-05-01

Self-oxidation/dissociation of some quaternary ammonium permanganates (QAPs), such as cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), have been studied spectrophotometrically in six different organic solvent media of different polarities wherein the compounds show good solubility and stability. The optical densities of the substrates at zero time (ODo) and first-order rate constants of dissociation (k1) have been determined from their successive scanning for 40 min. At comparable experimental conditions, absorption capabilities of the substrates are compared from the ODo values in various organic media; the stability of the solutions is compared from the successive scan spectra in those media. The ODo values and the k1 values have been plotted against some solvent parameters to understand their effects on the absorbance and reactivity of the QAPs. These data are also subjected to multiple regression analysis to explain the influence of various solvent parameters on the ion-pairing properties of the substrates, thus elucidating their effects on the process of self-oxidation/dissociation of the substrates.