Browsing by Author "Villarroel, M."
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- ItemAssessing the effect of fish size on species distribution model performance in southern Chilean rivers(2019) Zamorano, D.; Labra, F.A.; Villarroel, M.; Lacy, S.; Mao, Luca; Olivares, M.A.; Peredo Parada, M.
- ItemCorrosion products of reinforcement in concrete in marine and industrial environments(ELSEVIER SCIENCE SA, 2009) Vera, R.; Villarroel, M.; Carvajal, A. M.; Vera, E.; Ortiz, C.The corrosion products formed on embedded steel in concrete under simulated marine and industrial conditions and natural marine environment were studied. A 0.50 water/cement ratio concrete was used concrete 3.5% NaCl and 180 g L(-1) of H(2)SO(4) with 70 ppm of chloride ions solutions were used to simulate the synthetic medium. The initial electrochemical variables of the steel and pH, chlorides and sulfates profiles were measured according to the concrete depth. The morphology of the corrosive attack was determined electron microscopy (SEM), and the composition of the corrosion products was determined via scanning zer and an X-ray diffractorneter (XRD). The protective power of the corrosion products was evaluated through anodic polarization curves in a saturated Ca(OH)(2) Solution. The results from XRD and SEM show that all the resulting corrosion products correspond to lepidocrocite, goethite and magnetite mixtures: moreover, akaganeite was also identified under natural and simulated marine environments. Siderite was only detected in samples exposed to a natural marine environment. Concerning the protective nature of the corrosion products, these show lower performance in a simulated industrial environment, where the corrosion rate of the steel is up to 1.48 mu m year(-1). (C) 2008 Elsevier B.V. All rights reserved.
- ItemDURACON: Effect of the Environment on Reinforced Concrete Durability. Results of Chile after 5 years of Exposure(PONTIFICIA UNIV CATOLICA CHILE, ESCUELA CONSTRUCCION CIVIL, 2009) Vera, R.; Villarroel, M.; Delgado, D.; Carvajal, A. M.; De Barbieri, F.; Troconis, O.This study presents the results obtained in Chile under the international project "Influence of Environmental Action in the durability of concrete, DURACON" that joins 11 countries (Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Mexico, Spain, Uruguay, Portugal and Venezuela) that began in 2002. The project considers the exposure of reinforced concrete specimens for at least 5 years at stations located in the marine environment (Valparaiso-PUCV) and urban (PUC-Santiago). The concrete specimens were designed with w/c 0.45 and 0.65 and characterized by determining the compressive strength and tensile strength, elastic modulus, resistivity, capillary absorption, absorption and total porosity. The corrosion of steel was evaluated by corrosion potential and corrosion current and depth of carbonation in the concrete to determine the critical onset corrosion.
- ItemDURACON: influencia de la acción del medio ambiente en la durabilidad del concreto. Parte 2. Resultados de Chile después de 5 años de exposición(2009) Vera, Raúl; Villarroel, M.; Delgado, D.; Carvajal Guerra, Ana María; De Barbieri, F.
- ItemSUPPORT EFFECT ON CONVERSION OF QUINOLINE OVER ReS2 CATALYST(2016) Bassi, R.; Villarroel, M.; Gil-Llambias, F. J.; Baeza, P.; Garcia-Fierro, J. L.; Martinez, N.; Olivera, P.; Leiva, K.; Escalona, N.The conversion of quinoline over ReS2 supported on gamma-Al2O3, SiO2, ZrO2 and TiO2 catalysts in a batch reactor at 300 degrees C and 5 MPa of hydrogen pressure was studied. The catalysts were prepared by wet impregnation with a loading of 1.5 atoms of Re per nm(2) of support. The catalysts were characterized by N-2 adsorption, X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD). The Re(x)/supports catalysts displayed high activities for the conversion of quinoline, although negligible formation of N-free compounds (hydrodenitrogenation) were observed. The intrinsic activities of ReS2 were modified by the support decreased in the order: Re/TiO2 > Re/ZrO2 > Re/SiO2 > Re/g-Al2O3. The highest activity displayed by the Re/TiO2 catalyst was correlated with the Re dispersion and formation of ReS2 species. Meanwhile, the lower conversion of quinoline over the Re/ZrO2, Re/SiO2 and Re/g-Al2O3 catalysts was related to the combined effect of the textural properties of catalysts and the formation of ReS(2-x) species on the supports.
- ItemSynergism of Extruded and Monolithic Co-Mo/γ-AL2O3-Sepiolite Catalytic Systems in the Hydrodesulphurization Reaction(2016) Baeza, P.; Villarroel, M.; Villanueva, R.; Gil Llambías, Francisco Javier; Ávila, P.
- ItemThe effects of differential shortening and competent blocks on the structural development of Andean fold-and-thrust belts at 32°-34°S: Insights from analogue models(2023) Jara, P.; Herrera, S.; Villarroel, M.; Pinto, L.; Yagupsky, D.; Guzman, C.; Gutiwrrez, M.Andean fold-and-thrust belts (FTBs) in the western border of South America show important along-strike variations in their structural style (thin- or thick-skinned) and shortening magnitudes, among others. These variations can arise from multiple factors, such as depth-to-detachment, geometry, and thickness of underlying basins, structural highs, the competence of the units involved in deformation, pre-orogenic structure of the basement, the rheological state of the upper crust or latitudinal gradients in shortening, among others. We carry out a set of new analogue models to understand how two of these factors affect the development and the geometry of the thrust systems within the Andean Principal Cordillera and adjacent fold-and-thrust belts at 32 & DEG;-34 & DEG;S (La Ramada and Aconcagua FTBs). In this contribution, we present the results of analogue modeling of doubly-vergent thrust systems with a built-in heterogeneity that allow us to evaluate the influence of differential shortening and presence of competent blocks (of relatively higher cohesion) in the generation, evolution, and structural setting of Andean FTBs. We highlight that despite the similar pattern of differential shortening in the models, the presence of the competent block has a significant influence on the structural configuration and leads to greater topographic uplift. Differential shortening plays a role in accommodating deformation, but when a competent block is present, the faults bounding the block control the deformation, producing a notable curvature of the FTBs. Summarizing, the presence of a competent block significantly influences the structural configuration within a doubly-vergent thrust system, emphasizing the role of inherited architecture in the orogenic growth of the Southern Central Andes.