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Mexico City, Mexico

Rodriguez-Perez M.,CINVESTAV | Chacon C.,CICATA IPN | Palacios-Gonzalez E.,Mexican Institute of Petroleum | Rodriguez-Gattorno G.,CINVESTAV | Oskam G.,CINVESTAV
Electrochimica Acta | Year: 2014

Phase-pure WO3 materials with different crystal structures and morphologies are prepared using alcoholysis and partial hydrolysis under solvothermal conditions, and their promise for photoelectrochemical water oxidation is evaluated under simulated sunlight. The materials are obtained in the hexagonal, orthorhombic and monoclinic structures. Electrophoretic deposition under ambient conditions is used to prepare mechanically stable and well-adhered films on transparent conducting glass substrates. Photoelectrochemical characterization of the films illustrates that sufficient electrical interconnectivity is achieved; however, a heat treatment at 500 °C dramatically improves the photocurrent, which is related to the passivation of defects and traps of the WO3 materials. The orthorhombic and monoclinic materials, the latter depending on the morphology and texture, achieve the highest photocurrents corresponding to water oxidation, while the hexagonal material has the lowest photocurrents. The novel orthorhombic material prepared in this work shows good promise for water oxidation, also because of the low density of electron traps as inferred from experiments under modulated illumination using a chopper. The properties of the monoclinic material depend on the morphology, in particular the texture. The electrochemical properties for a rod morphology with texture defined by the (002) or (020) reflections are characterized by lower photocurrents and a higher trap density, while a square platelets type of morphology with a texture characterized by the (002) reflection results in the highest photocurrents. The results indicate that electrophoretically deposited films of WO3 materials with shapes corresponding to two or three dimensions have better photoelectrochemical properties than one dimensional shapes such as rods and wires. © 2014 Elsevier Ltd. All rights reserved. Source

Vazquez-Carrillo M.G.,INIFAP CEVAMEX | Santiago-Ramos D.,PROPAC | Gaytan-Martinez M.,PROPAC | Morales-Sanchez E.,CICATA IPN | Guerrero-Herrera M.D.J.,INIFAP CIRNO
LWT - Food Science and Technology | Year: 2015

The objective of this study was to assess thermal, rheological and quality properties of grain, masa (ground nixtamalized corn), and tortillas made with high-oil maize hybrids and compare them with landraces. Grains of high-oil hybrids were harder (flotation index 10-36) with high onset, peak and final gelatinization temperatures, which were reflected in lower masa and tortilla yield. However, the tortillas had higher oil content (3.2-4.5g/100g) than those made with landraces (2.9-3.0 g/100g). Tortillas made with the yellow hybrids were softer (1.8 N). Pepitilla had the highest viscosity in grain, masa and tortillas, reflected in greater water absorption and masa and tortilla yield (1.61 kg/kg maize). A close relationship was found between G' and G″ and retained pericarp and oil content in masa; higher content of natural gums produced firmer masa with higher viscoelasticity. The high oil content in tortillas reduced their water absorption and starch swelling capacity but inhibited starch retrogradation, so they remained softer during storage. © 2014 Elsevier Ltd. Source

Marcano G.,University of Los Andes, Venezuela | Rincn C.,University of Los Andes, Venezuela | Lpez S.A.,University of Los Andes, Venezuela | Snchez Prez G.,University of Los Andes, Venezuela | And 3 more authors.
Solid State Communications | Year: 2011

The Raman-active phonons in semiconductor Cu2SnSe3 that crystallizes in the monoclinic structure with space group Cc were studied by measuring unpolarized Raman spectrum. The experimental Raman line wave numbers for the phonon modes were compared to those reported and to the results of lattice dynamical calculations based on simplified current models reported in the literature. From the factor group analysis of the zone-center vibrational modes, the symmetry of the observed Raman lines were tentatively assigned. The most intense A′ mode at 178 cm-1; the lowest- and highest-frequency A′ modes at 83 and 244 cm-1, respectively; A″ modes at 204, 231 and 291 cm-1; and a band at about 363 cm-1 which probably corresponds to an overtone on the strong peak at 178 cm-1, have been observed in this compound. © 2010 Elsevier Ltd. All rights reserved. Source

Terven J.R.,CICATA IPN | Raducanu B.,CVC | Meza M.-E.,UAQ | Salas J.,CICATA IPN
Proceedings of the IEEE International Conference on Computer Vision | Year: 2016

Mirroring occurs when one person tends to mimic the non-verbal communication of their counterparts. Even though mirroring is a complex phenomenon, in this study, we focus on the detection of head-nodding as a simple non-verbal communication cue due to its significance as a gesture displayed during social interactions. This paper introduces a computer vision-based method to detect mirroring through the analysis of head gestures using wearable cameras (smart glasses). In addition, we study how such a method can be used to explore perceived competence. The proposed method has been evaluated and the experiments demonstrate how static and wearable cameras seem to be equally effective to gather the information required for the analysis. © 2015 IEEE. Source

Garay-Ramirez B.,CICATA IPN | Cruz-Orea A.,CINVESTAV | San Martin-Martinez E.,CICATA IPN
International Journal of Thermophysics | Year: 2015

Sodium acetate trihydrate (SAT) is used as a phase change material (PCM) because of its high latent heat of fusion. Mixtures were prepared with SAT, a blend of the polymer sodium carboxymethil cellulose (CMC) and silica gel, silver nanoparticles (AgNPs), and anhydrous sodium sulfate to form a composite-PCM (c-PCM) based on SAT; the relative proportions of CMC/silica gel in the blend and AgNP content were varied according to a central composite experimental design. The thermal properties were determined for raw SAT, CMC, Na2SO4, and c-PCM samples. The thermal effusivity (es) of samples was evaluated by the inverse photopyroelectric technique. The thermal diffusivity (Ds) was obtained for samples by the open photoacoustic cell technique. The thermal conductivity (ks) was calculated from the obtained es and Ds values. To assess the thermal performance of the c-PCM compared to raw SAT, samples were studied through differential scanning calorimetry which served to determine the latent heat recovery (LHR). Properties es, Ds, ks, and LHR were analyzed by response surface methodology and compared. The SAT-based c-PCM was found to be more thermally conductive than raw SAT. The best LHR with good thermal diffusivity and thermal conductivity was identified in the region of the central composite experimental design with medium–low AgNPs and higher proportions of CMC in the polymer blend. © 2015, Springer Science+Business Media New York. Source

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