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Puebla de Zaragoza, Mexico

Jaime V.B.J.,Puebla Institute of Technology
International Journal of ChemTech Research | Year: 2014

A series of ferrocenylmono-and dichalcone derivatives have been synthesized under solvent-free conditions via Claisen-Schmidt condensations between aryl/ferrocenyl ketones and aryl/ferrocenyl aldehydes by just grinding in an agate mortar. All the reactions occur in a short time with excellent yields (>85%) of steroselective trans-conformation in the chalcones. The structures of all the compounds have been characterized by FT-IR, 1H NMR, 13C NMR and EI-MS and elemental analyses.

Santacruz-Vazquez V.,Autonomous University of Puebla | Santacruz-Vazquez C.,Autonomous University of Puebla | Laguna Cortes J.O.,Puebla Institute of Technology
Vitae | Year: 2015

Background: Foams are colloidal dispersions of a gas suspended in a dispersing phase, which consisting of a semi-freeze-dried or viscous liquid phase. The physical properties of food foams are the result of the bubble characteristics and their spatial arrangement. Objectives: The aim of this work was to obtain foams of A. vera gel and guar gum and describe the changes in their physical properties and microstructure during freeze-drying using the fractal dimension concept and image analysis techniques. Methods: The porosity, density, and volume expansion factor of the fresh foams that were based on the A. vera foams were determined. The kinetics of foam texture, color, porosity and microstructure of the freeze-dried foams were obtained. The fractal texture dimension of surface (FDSDBC) and microstructure (FDESEM) of the foams were determined as indicators of structural changes after freeze-drying. The guar gum concentrations used to obtain the A. vera prefoam were expressed in w/w as F1 (control sample without gum), F2 (2%), F3 (4%) and F4 (6%). Results: We obtained stable freeze-dried foams of Aloe vera gel and guar gum. The porosity, density and volume expansion factor of the fresh and freeze-dried foams were affected by the addition of the guar gum. Changes in the topology of the freeze-dried foam surface during the drying process resulted in a high rugosity compared with the original smooth surface. The microstructure of the dried foam samples suggested a relationship between the gum concentration of the prefoam A. vera gel mixture and the physical properties before and after freeze-drying, such as an increase in the microstructural alterations and surface roughness during freeze-drying. The roughness of the freeze-dried foam surface, described by the FDSDBC represented the macroscopic physical changes of the samples and correlated with the changes in the foam microstructure, which were described by the fractal dimension of the Environmental Scanning Electron Microscopy ESEM microphotographs (FDESEM). Conclusions: The digital analysis of the structure and porosity of the freeze-dried foam can be used to quantify the effect of gum concentrations on the morphological features and physical properties of foams during freeze-drying. © 2015, Universidad de Antioquia. All rights reserved.

Estrada-Medina H.,Autonomous University of Yucatan | Graham R.C.,University of California at Riverside | Allen M.F.,University of California at Riverside | Jimenez-Osornio J.J.,Autonomous University of Yucatan | Robles-Casolco S.,Puebla Institute of Technology
Plant and Soil | Year: 2013

Background and Aims: With limited soil depth in northern Yucatán (<30 cm), roots grow deeper through rock fractures and dissolution karst features (i. e., cavities, including soil-filled ones known as soil pockets). We assessed the importance of limestone bedrock and dissolution karst features on tree root growth. Methods: Fieldwork was conducted in a limestone quarry where the relative proportions of rock matrix, empty cavities, and soil pockets were calculated by observing recently exposed walls. Physical properties of rocks, topsoil, and soil pockets were analyzed. Root distribution was assessed and roots identified. Results: Soil pockets represented 9% of the rock matrix. The physical properties of rock layers were different with depth. Available water capacity is higher in soil (0. 11 m-3 m-3) than in rock layers (<0. 05 m-3 m-3). But potential available water was much higher in subsurface features than top soil. Conclusions: Dissolution karts features allow roots to grow deep into the bedrock, tapping water stored there. Although the limestone upper layer in northern Yucatan is highly restrictive to root growth, subsurface limestone layers and soil pockets are not restrictive and can hold important amounts of water. © 2012 Springer Science+Business Media B.V.

Valdez S.,National Autonomous University of Mexico | Pech-Canul M.I.,CINVESTAV | Ascencio-Gutierrez J.A.,National Autonomous University of Mexico | Casolco S.R.,Puebla Institute of Technology
International Journal of Electrochemical Science | Year: 2013

The chemical composition of metallic AlZnAg alloy is related with microstructure in order to know their influence on electrochemical degradation. The microstructure has been characterized by high transmission electron microscopy with energy-dispersive X-ray. The electrochemical behavior has been tested by potentiodynamic polarization tests. In addition, weight loss analysis was carried out for the corrosion rate. In electrochemical tests the results showed the significant influence of silver concentration on the dissolution reactions of Al-matrix, solid solution rich-Zn, and AgZn3 precipitate phase. The electrochemical investigation shows that the corrosion rate increases with the silver additions. Likewise, it was moreover evidenced the development of a film passive layer for the maximum silver content alloys; the passivity of this cover could be broken due to the existence of precipitate phase AgZn3. Based on this behavior the AgZn3 particles, and microstructural phases play a significant role in the corrosion process for the metallic AlZn alloys. © 2013 by ESG.

Ayon-Beato E.,CINVESTAV | Ayon-Beato E.,Austral University of Chile | Bravo-Gaete M.,University of Talca | Correa F.,Leibniz University of Hanover | And 5 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

The aim of this paper is to confirm in new concrete examples that the semiclassical entropy of a three-dimensional Lifshitz black hole can be recovered through an anisotropic generalization of the Cardy formula derived from the growth of the number of states of a boundary nonrelativistic field theory. The role of the ground state in the bulk is played by the corresponding Lifshitz soliton obtained by a double Wick rotation. In order to achieve this task, we consider a scalar field nonminimally coupled to new massive gravity for which we study different classes of Lifshitz black holes as well as their respective solitons, including new solutions for a dynamical exponent z=3. The masses of the black holes and solitons are computed using the quasilocal formulation of conserved charges recently proposed by Gim et al. and based on the off-shell extension of the ADT formalism. We confirm the anisotropic Cardy formula for each of these examples, providing a stronger base for its general validity. Consistently, the first law of thermodynamics together with a Smarr formula are also verified. © 2015 American Physical Society.

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