Browsing by Author "Contreras, R."

Now showing 1 - 20 of 27
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    A machine learned classifier for RR Lyrae in the VVV survey
    (2016) Elorrieta López, Felipe; Eyheramendy Duerr, Susana; Jordán Colzani, Andrés Cristóbal; Dekany, Istvan; Catelan, Márcio; Angeloni, Rodolfo; Alonso, J.; Contreras, R.; Gran, F.; Hajdu, G.; Espinoza, N.; Saito, R.; Minniti, D.
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    A theoretical study on the relationship between nucleophilicity and ionization potentials in solution phase
    (2003) Contreras, R.; Andres, J.; Safont, V.S.; Campodónico Galdames, Paola Rossana; Santos Blanco, José Guillermo
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    Comparison between experimental and theoretical scales of electrophilicity in benzhydryl cations
    (2002) Perez, P.; Toro Labbé, Alejandro; Aizman, Andrés; Contreras, R.
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    D-serine released by astrocytes in brainstem regulates breathing response to CO2 levels
    (2017) Bernhardi Montgomery, Rommy von; Eugenin, J.; Llona, I.; Zúñiga, G.; Contreras, R.; Olivares, M.; Beltrán, S.
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    Experimental and theoretical study on the substitution reactions of aryl 2,4-dinitrophenyl carbonates with quinuclidines
    (2006) Castro R., Enrique; Campodónico Galdames, Paola Rossana; Contreras, R.; Fuentealba, P.; Santos Blanco, José Guillermo; Leis, J.R.; Garcia-Rio, L.; Saez, J.A.; Domingo, L.R.
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    Gutmann’s Donor Numbers Correctly Assess the Effect of the Solvent on the Kinetics of SNAr Reactions in Ionic Liquids
    (2016) Alarcon, J.; Contreras, R.; Tapia Apati, Ricardo; Campodónico Galdames, Paola Rossana
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    HSAB analysis of charge transfer in the gas-phase acid-base equilibria of alkyl-substituted alcohols
    (1999) Perez, Patricia; Toro Labbé, Alejandro; Contreras, R.
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    Kinetic and theoretical study on nucleofugality in the phenolysis of 3-nitrophenyl and 4-nitrophenyl 4-cyanophenyl thionocarbonates
    (2013) Castro R., Enrique; Cañete Molina, Álvaro; Campodónico Galdames, Paola Rossana; Cepeda, M.; Pavez Guerrero, Paulina Isabel; Contreras, R.; Santos, José G.
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    Mapping the outer bulge with RRab stars from the VVV Survey
    (2016) Gran Merino, Felipe Eduardo; Minniti, D.; Saito, R.; Zoccali, Manuela; Gonzalez, O.; Navarrete, C.; Catelan, Márcio; Contreras, R.; Elorrieta López, Felipe; Eyheramendy Duerr, Susana; Jordán Colzani, Andrés Cristóbal
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    Mechanism for the SNAr reaction of atrazine with endogenous thiols: experimental and theoretical study
    (2017) Calfumán, K.; Gallardo-Fuentes, S.; Contreras, R.; Tapia Apati, Ricardo; Campodónico Galdames, Paola Rossana
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    Mechanistic pathways of aromatic nucleophilic substitution in conventional solvents and ionic liquids
    (2014) Gazitúa López, Marcela Ivonne; Tapia Apati, Ricardo; Contreras, R.; Campodónico Galdames, Paola Rossana
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    MOONS: The New Multi-Object Spectrograph for the VLT
    (2020) Cirasuolo, M.; Fairley, A.; Rees, P.; González, O. A.; Taylor, W.; Maiolino, R.; Afonso, J.; Evans, C.; Flores, H.; Lilly, S.; Oliva, E.; Paltani, S.; Vanzi, L.; Abreu, M.; Accardo, M.; Adams, N.; Álvarez Méndez, D.; Amans, J. -P.; Amarantidis, S.; Atek, H.; Atkinson, D.; Banerji, M.; Barrett, J.; Barrientos, F.; Bauer, F.; Beard, S.; Béchet, C.; Belfiore, A.; Bellazzini, M.; Benoist, C.; Best, P.; Biazzo, K.; Black, M.; Boettger, D.; Bonifacio, P.; Bowler, R.; Bragaglia, A.; Brierley, S.; Brinchmann, J.; Brinkmann, M.; Buat, V.; Buitrago, F.; Burgarella, D.; Burningham, B.; Buscher, D.; Cabral, A.; Caffau, E.; Cardoso, L.; Carnall, A.; Carollo, M.; Castillo, R.; Castignani, G.; Catelan, Márcio; Cicone, C.; Cimatti, A.; Cioni, M. -R. L.; Clementini, G.; Cochrane, W.; Coelho, J.; Colling, M.; Contini, T.; Contreras, R.; Conzelmann, R.; Cresci, G.; Cropper, M.; Cucciati, O.; Cullen, F.; Cumani, C.; Curti, M.; Da Silva, A.; Daddi, E.; Dalessandro, E.; Dalessio, F.; Dauvin, L.; Davidson, G.; de Laverny, P.; Delplancke-Ströbele, F.; De Lucia, G.; Del Vecchio, C.; Dessauges-Zavadsky, M.; Di Matteo, P.; Dole, H.; Drass, H.; Dunlop, J.; Dünner, R.; Eales, S.; Ellis, R.; Enriques, B.; Fasola, G.; Ferguson, A.; Ferruzzi, D.; Fisher, M.; Flores, M.; Fontana, A.; Forchi, V.; Francois, P.; Franzetti, P.; Gargiulo, A.; Garilli, B.; Gaudemard, J.; Gieles, M.; Gilmore, G.; Ginolfi, M.; Gomes, J. M.; Guinouard, I.; Gutierrez, P.; Haigron, R.; Hammer, F.; Hammersley, P.; Haniff, C.; Harrison, C.; Haywood, M.; Hill, V.; Hubin, N.; Humphrey, A.; Ibata, R.; Infante, L.; Ives, D.; Ivison, R.; Iwert, O.; Jablonka, P.; Jakob, G.; Jarvis, M.; King, D.; Kneib, J. -P.; Laporte, P.; Lawrence, A.; Lee, D.; Li Causi, G.; Lorenzoni, S.; Lucatello, S.; Luco, Y.; Macleod, A.; Magliocchetti, M.; Magrini, L.; Mainieri, V.; Maire, C.; Mannucci, F.; Martin, N.; Matute, I.; Maurogordato, S.; McGee, S.; Mcleod, D.; McLure, R.; McMahon, R.; Melse, B. -T.; Messias, H.; Mucciarelli, A.; Nisini, B.; Nix, J.; Norberg, P.; Oesch, P.; Oliveira, A.; Origlia, L.; Padilla, N.; Palsa, R.; Pancino, E.; Papaderos, P.; Pappalardo, C.; Parry, I.; Pasquini, L.; Peacock, J.; Pedichini, F.; Pello, R.; Peng, Y.; Pentericci, L.; Pfuhl, O.; Piazzesi, R.; Popovic, D.; Pozzetti, L.; Puech, M.; Puzia, T.; Raichoor, A.; Randich, S.; Recio-Blanco, A.; Reis, S.; Reix, F.; Renzini, A.; Rodrigues, M.; Rojas, Felipe; Rojas-Arriagada, Á.; Rota, S.; Royer, F.; Sacco, G.; Sanchez-Janssen, R.; Sanna, N.; Santos, P.; Sarzi, M.; Schaerer, D.; Schiavon, R.; Schnell, R.; Schultheis, M.; Scodeggio, M.; Serjeant, S.; Shen, T. -C.; Simmonds, C.; Smoker, J.; Sobral, D.; Sordet, M.; Spérone, D.; Strachan, J.; Sun, X.; Swinbank, M.; Tait, G.; Tereno, I.; Tojeiro, R.; Torres, M.; Tosi, M.; Tozzi, A.; Tresiter, E.; Valenti, E.; Valenzuela Navarro, Á.; Vanzella, E.; Vergani, S.; Verhamme, A.; Vernet, J.; Vignali, C.; Vinther, J.; Von Dran, L.; Waring, C.; Watson, S.; Wild, V.; Willesme, B.; Woodward, B.; Wuyts, S.; Yang, Y.; Zamorani, G.; Zoccali, M.; Bluck, A.; Trussler, J.
    MOONS is the new Multi-Object Optical and Near-infrared Spectrograph currently under construction for the Very Large Telescope (VLT) at ESO. This remarkable instrument combines, for the first time, the collecting power of an 8-m telescope, 1000 fibres with individual robotic positioners, and both low- and high-resolution simultaneous spectral coverage across the 0.64-1.8 μm wavelength range. This facility will provide the astronomical community with a powerful, world-leading instrument able to serve a wide range of Galactic, extragalactic and cosmological studies. Construction is now proceeding full steam ahead and this overview article presents some of the science goals and the technical description of the MOONS instrument. More detailed information on the MOONS surveys is provided in the other dedicated articles in this Messenger issue....
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    Near-IR period-luminosity relations for pulsating stars in omega Centauri (NGC 5139)
    (2017) Navarrete Silva, Camila Andrea; Catelan, Márcio; Contreras, R.; Alonso, J.; Gran, F.; Dekany, Istvan; Minniti, D.
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    Platinum(II) complexes with dithiolates and phosphinites as ligands: Crystal structure of [Pt{S2CO}{P(OMe)Ph(2)}(2)]
    (PERGAMON-ELSEVIER SCIENCE LTD, 1996) Contreras, R.; Valderrama, M.; Riveros, O.; Moscoso, R.; Boys, D.
    Reaction of the complex [PtCl{P(O)Ph(2)} {P(OH)Ph(2)}(2)] with silver or thallium derivatives of dithiolate ligands led to neutral complexes of general formula [Pt{S-S} {P(O)Ph(2)} {P(OH)Ph(2)}], where {S-S}(-) ={S(2)CNEt(2)}(-) (1), {S2P(OEt)2}(-) (2) and {S(2)COEt}(-) (3). Complexes 2 and 3 reacted with an excess of NaI in acetone solution by dealkylation of the coordinated dithiolate ligand and formation of the compounds [Pt{S2P(O) (OEt)} {P(O)Ph(2)} {P(OH)Ph(2)}] Na (4) and [Pt{S2CO}{P(O)Ph(2)}{P(OH)Ph(2)}] Na (5), respectively. The corresponding tetraphenylphosphonium derivatives (6, 7) were prepared by a metathetical reaction of these complexes with Ph(4)PBr in acetone solution. Related dithiolate complexes were obtained by reaction of the complex [Pt{S-S}(2)] with P(OMe)Ph(2) in molar ratio 1:2. Thus, the reaction of [Pt{S(2)COEt}(2)] in dichloromethane solution at room temperature gave [Pt{S(2)COEt} {P(OMe)Ph(2)}(2)] Cl (8). This complex reacted with NaI in acetone to form the neutral compound [Pt{S2CO} {P(OMe)Ph(2)}(2)] (9). When the reaction was carried out in dichloromethane at reflux temperature using [Pt{S2P(OEt)(2)}(2)] as starting material, the neutral compound [Pt{S2P(O)(OEt)} {P(OMe)Ph(2)}(2)] (10) was obtained. The crystal structure of the complex 9 has been determined by X-ray diffraction. The neutral complex shows a nearly square-planar coordination of the metal and a planar dithiocarbonate ligand.
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    Rhodium(III) and ruthenium(II) complexes with the chiral phosphine-alcohol PH2PCH2CHMeCH2OH. Synthesis and characterisation
    (SOC CHILENA QUIMICA, 2002) Sanhueza, J.; Contreras, R.; Valderrama, M.
    Reaction of the dinuclear complex [{(eta(5)-C5Me5)RhCl}(2)(mu-Cl)(2)] with the chiral phosphine (R)-Ph2PCH2CHMeCH2OH leads to the complex [{(eta(5)-C5Me5)RhCl2(eta(1)-Ph2PCH2CHMeCH2OH-P)}](1). This reaction, in the presence of AgBF4, yields the cationic compound [{(eta(5)-C5Me5)RhCl(eta(2)-Ph2PCH2CHMeCH2OH-P,O)}]BF4 (2). Variable-temperature H-1 NMR and circular dichroism experiments support the stereoselective eta(2)-chelate coordination of the ligand and the proposed configuration for the metal centre. In a similar way, the reaction of the dimer [{(eta(6)-C6Me6)RuCl}(2)(mu-Cl)(2)] with the ligands (R)- and (S)-Ph2PCH2CHMeCH2OH afford the neutral complexes [(eta(6)-C6Me6)RuCl2{eta(1)-PPh2CH2CHMeCH2OH-P}] [R-ligand (3), S-ligand (4)], which in turn react with AgBF4 to give the cationic compounds [(eta(6)-C6Me6)RuCl{eta(2)-PPh2CH2CHMeCH2OH-P,O}]BF4 [R-ligand (5), S-ligand (6)]. All complexes have been characterised by elemental analysis, IR and multinuclear NMR spectroscopies.
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    RR Lyrae stars in M31 globular clusters: B514
    (2008) Contreras, R.; Federici, L.; Clementini, G.; Cacciari, C.; Merighi, R.; Kinemuchi, K.; Catelan , Marcio; Fusi Pecci, F.; Marconi, M.; Pritzl, B.; Smith, H.
    We present preliminary results of a variable star search in the metal-poor globular cluster B514 of the Andromeda galaxy (M31), based on Hubble Space Telescope Wide Field Planetary Camera 2 and Advanced Camera for Surveys observations. A large number of RR Lyrae stars have been identified for the first time in a globular cluster of M31. The average period of the RR Lyrae variables (< Pab > = 0.58 days and < Pc > = 0.35 days, for fundamental-mode and first-overtone pulsators, respectively) and the position in the period-amplitude diagram both suggest that B514 is likely an Oosterhoff I cluster, contrary to the general behaviour of the metal-poor globular clusters in the Milky Way, which show instead Oosterhoff type II pulsation properties....
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    RR Lyrae Stars: Period-Luminosity Relations and Oosterhoff Groups
    (2003) Smith, H. A.; Pritzl, B. J.; Catelan, Marcio; Sweigart, A. V.; De Lee, N.; Contreras, R.
    We use new observations and data from the literature to construct I band period-luminosity relations for RR Lyrae stars in globular clusters. We present synthetic horizontal branches made from theoretical evolutionary models to understand better the effect which horizontal branch morphology has upon the period-luminosity relations in I and several other passbands. We also use the observed relations to address the question of the prevalence of second overtone pulsators among the RR Lyrae stars. We will review an ongoing observational program designed to obtain photometry for variable stars in globular clusters that show the second parameter effect and that cannot be easily placed within the two usual Oosterhoff groups. We thank the National Science Foundation for partial support of this work....