Browsing by Title Facultad de Ciencias

Now showing items 4117-4136 of 8181

    • A hybrid organic-inorganic layered TiO2 based nanocomposite for sunlight photocatalysis 
      Benavente Espinosa, Eglantina; Maldonado, Carlos; Devis, Sindy; Díaz, Leslie; Lozano, Harold; Sotomayor Torres, Clivia; González Moraga, Guillermo (The Royal Society of Chemistry, 2016)
      A novel hybrid nanocomposite constituted of single TiO2 nanosheets sandwiched between stearic acid self-assembled monolayers was synthesized and tested in the photodegradation of methylene blue under sunlight. The product ...
    • Hybridization in the Genus Baccharis : Baccharis linearis χ B. macraei 
      Faini, Francesca; Hellwlg, Frank; Labbé, Cecilia; Castillo, Mariano (1991)
      On morphological, chemical composition and field distribution studies, the hybrid condition of Baccharis χ intermedia DC. is discussed. B. linearis (Ruiz et Pavón) Pers. and B. macraei Hook, et Arn. are the parental species. ...
    • Hydraulic lift in three shrub species from the Chilean coastal desert 
      Muñoz, M. R.; Squeo, F. A.; León, M. F.; Tracol, Y.; Gutiérrez, J. R. (ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2008-05)
      Hydraulic lift is defined as the passive movement of water through roots from wetter, deeper soil layers into drier shallower layers along a gradient in soil water potential. This process is generally found in plant species ...
    • Hydroclimatic conditions trigger record harmful algal bloom in western Patagonia (summer 2016) 
      León Muñoz, Jorge; Urbina, Mauricio A.; Garreaud Salazar, René; Iriarte, José Luis (Nature Publishing Group, 2018)
      A harmful algal bloom (HAB) of the raphidophyta alga Pseudochattonella cf. verruculosa during the 2016 austral summer (February-March) killed nearly 12% of the Chilean salmon production, causing the worst mass mortality ...
    • Hydrogen Bond Contribution to Preferential Solvation in SNAr Reactions 
      Ormazábal Toledo, Rodrigo; Santos, José G.; Ríos, Paulina; Castro, Enrique A.; Campodónico, Paola R.; Contreras Ramos, Renato (American Chemical Society, 2013)
      Preferential solvation in aromatic nucleophilic substitution reactions is discussed using a kinetic study complemented with quantum chemical calculations. The model system is the reaction of a series of secondary ...
    • Hydrogen bonding and dissociation effects on the gas phase proton transfer reactions of ozone 
      Contreras Ramos, Renato; Safont, Vincent S.; Andrés, J.; Pérez, Patricia; Aizman, Arie; Tapia, O. (Springer New York LLC, 1998)
      © Springer-Verlag 1998. Recently, the proton affinity (PA) of ozone was experimentally determined by Cacace and Speranza [Science (1994) 265: 208] using a bracketing technique that involved the proton transfer (PT) reactions: ...
    • Hydrogen bonds and asymmetrical heat diffusion in alpha-helices. A computational analysis 
      Miño Galaz, Germán; Gutiérrez Gallardo, Gonzalo (Elsevier, 2015)
      In this work, we report the heat rectifying capability of a-helices. Using molecular dynamics simulations we show an increased thermal diffusivity in the C-Terminal to N-Terminal direction of propagation. The origin of ...
    • Hydrogen bonds and heat diffusion in α‑helices: a computational study 
      Miño, Germán; Barriga, Raúl; Gutiérrez Gallardo, Gonzalo (American Chemical Society, 2014)
      Recent evidence has shown a correlation between the heat diffusion pathways and the known allosteric communication pathways in proteins. Allosteric communication in proteins is a central, yet unsolved, problem in ...
    • Hydrogen peroxide increases during endodormancy and decreases during budbreak in grapevine (Vitis vinifera L.) buds 
      Pérez Correa, Francisco; Noriega, Ximena; Rubio Vargas, Sebastián (MDPI, 2021)
      Changes in the level of hydrogen peroxide (H2O2) is a good indicator to monitor fluctuations in cellular metabolism and in the stress responses. In this study, the changes in H2O2 content during bud endodormancy (ED) and ...
    • Hydrogen Storage in Palladium Hollow Nanoparticles 
      Valencia, Felipe; González, Rafael I.; Tramontina, Diego; Rogan Castillo, José; Valdivia Hepp, Juan; Kiwi Tichauer, Miguel; Bringa, Eduardo (American Chemical Society, 2016-10-20)
      The potential and properties of palladium hollow nano particles (hNPs) as a possible H storage material are explored by means of classical molecular dynamics (MD) simulations. First, we study the stability of pure Pd hNPs ...
    • Hydrogen-bonded supramolecular array in the crystal structure of ethyl 7-hydroxy-2-oxo-2h-chromene-3-carboxylate ... 
      Galdámez, Antonio; García Beltrán, Olimpo; Cassels Niven, Bruce (Sociedad Chilena de Quimica, 2011)
      The crystal structure of ethyl 7-hydroxy-2-oxo-2H-chromene-3-carboxylate monohydrate (1), C12H10O5.H2O, was established by X-ray crystallographic analysis. The molecule of the title compound is essentially planar except ...
    • Hydrolyses of terpenoid diphosphates. Effects of azide ion on products of hydrolysis 
      Alarcón, Maritza; Cori, Osvaldo; Rojas, M. Cecilia; Pavez, Hernán; Bacaloglu, Radu; Bunton, Clifford A. (1992)
      Hydrolysis of geranyl diphosphate (GPP) at pH 7 in water gives largely linalool (LOH) + geraniol (GOH) in the ratio of 3:1. Added N−3 generates mixed acylic allylic azides and increases the LOH GOH ratio to 15:1 in 2 M ...
    • Hydroxamic acid content in wild and cultivated gramineae 
      Zúñiga, Gustavo E.; Argandoña, Víctor H.; Niemeyer, Hermann M.; Corcuera, Luis J. (1983)
      The content of two hydroxamic acids, 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), in cultivated and wild species of Gramineae was determined. Zea mays and Triticum ...
    • Hydroxamic acid content of perennial triticeae 
      Copaja Castillo, Sylvia; Barria, Bernardita N.; Niemeyer Marich, August (1991)
      Ninety-four accessions of perennial Triticeae were examined for content of the hydroxamic acids DIBOA and DIMBOA. Levels of DIBOA (up to 44 mmolkg-1 fr. wt) were higher than those of DIMBOA (up to 4.5 mmol kg-1 fr.wt). The ...
    • Hydroxamic acid content of triticum species 
      Niemeyer, Hermann M. (Kluwer Academic Publishers, 1988)
      Fifty-five accessions of Triticum species were analyzed for content of hydroxamic acids (Hx), a natural resistance factor against various organisms. Hx were found in all accessions analyzed. Extreme values were found in ...
    • Hydroxamic acid glucosides in honeydew of aphids feeding on wheat 
      Givovich, A.; Morse, S.; Cerda, H.; Niemeyer, H. M.; Wratten, S. D.; Edwards, P. J. (Kluwer Academic Publishers-Plenum Publishers, 1992)
      DIMBOA glucoside (2-O-/gb-D-glucopyranosyl-4-hydroxy-7-meth-oxy-1,4-benzoxazin-3-one), the main hydroxamic acid (Hx) in intact wheat plants, was detected in the honey dew of Rhopalosiphum padi feeding on seedlings of six ...
    • Hydroxamic acids (4-hydroxy-1,4-benzoxazin-3-ones), defence chemicals in the gramineae 
      Niemeyer Marich, August (1988)
      Hydroxamic acids of the type 4-hydroxy-1,4-benzoxazm-3-ones constitute one of the most extensively studied secondary metabolites m relation to host plant resistance to pests and diseases They play a maJor role in the defence ...
    • Hydroxamic acids accumulation by wheat callus 
      Zúñiga, Gustavo E.; Copaja, Sylvia V.; Bravo, Hector R.; Argandoña, Victor H. (1990)
      Hydroxamic acids were quantified by HPLC in leaves of one-week-old seedlings and in 30 day-old callus tissues of four wheat cultivars. Leaves accumulated preferentially 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA). ...
    • Hydroxamic acids affecting barley yellow dwarf virus transmission by the aphid Rhopalosiphum padi 
      Givovich,; Niemeyer, (1991)
      2,4‐Dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one (DIMBOA), a hydroxamic acid (Hx) occurring in wheat, was shown to deter feeding by the aphid Rhopalosiphum padi (L.), and to reduce BYDV transmission to the plant. Dual choice ...
    • Hydroxamic acids derived from 2-hydroxy-2h-1,4-benzoxazin-3(4h)-one: Key defense chemicals of cereals 
      Niemeyer, Hermann M. (2009)
      Many cereals accumulate hydroxamic acids derived from 2-hydroxy-2H-1,4- benzoxazin-3(4H)-one. These benzoxazinoid hydroxamic acids are involved in defense of maize against various lepidopteran pests, most notably the ...