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Hernandez-Campos F.J.,Zacatepec Institute of Technology | Brito-De La Fuente E.,Fresenius Kabi Deutschland GmbH | Torrestiana-SANCHEZ B.,Instituto Tecnologico De Veracruz
Journal of Agricultural and Food Chemistry | Year: 2010

Immunoglobulin Y (IgY) was purified from hen egg yolk water-soluble protein fraction by ultrafiltration-diafiltration with different membranes. The effect of changing solution properties (pH and Ionic strength) on purification factor (P), process selectivity (ψ), and IgY recovery (RIgy) was studied. Salt presence (150 and 1500 mM) decreased the selectivity and purity factor. This effect was more evident at pH values closer to or higher than the IgY's isoelectric point. The best results were obtained in the absence of salt at pH values of 5.7 and 6.7 using poliethersulfone (PES) and modified PES (MPES), respectively. Process selectivity was doubled, and IgY's purification factors were increased in more than 1 order of magnitude when diafiltration was used. Results from this work show the potential of membrane technology for the purification of IgY from hen's egg yolk. © 2009 American Chemical Society.

Lopez-Chavez R.,National Autonomous University of Mexico | Lopez-Chavez R.,Zacatepec Institute of Technology | Cuentas-Gallegos A.K.,National Autonomous University of Mexico
Journal of New Materials for Electrochemical Systems | Year: 2013

In the present work we show results related with the influence of the binder type used to elaborate active electrodes made of activated carbon (DLC) for the assembly of supercapacitor cells. A Nafion 5%w solution and/or Kinar Flex (Polyvinylidene fluoride, PVDF) were used as binders at different concentrations, using DLC carbon as the active material to make the electrodes by aerography, and carbon paper as support and current collector. Thickness of the electrodes was controlled by the weight of active material (DLC carbon). Cyclic voltammetry technique was used to investigate the intrinsic capacitive nature of these electrodes, increasing this value from 120 F/g to 245 F/g at 20 mV/s just by improving the type and amount of binder, and the thickness of the electrode. Symmetric 2-electrode cells assembled with binder-free electrodes were electrochemically characterized by galvanostatic cycling, showing capacitance values of 38F/g and a stable behavior during 7000 charge-discharge cycles. © J. New Mat. Electrochem. Systems.

Romero Ugalde H.M.,CNRS Systems and Information Sciences Lab LSIS | Romero Ugalde H.M.,CENIDET | Carmona J.-C.,CNRS Systems and Information Sciences Lab LSIS | Alvarado V.M.,CENIDET | Reyes-Reyes J.,Zacatepec Institute of Technology
Neurocomputing | Year: 2013

In this paper a dedicated recurrent neural network design and a model reduction approach are proposed in order to improve the balance between complexity and quality of black box nonlinear system identification models. The proposed neural network design, based on a three-layers architecture, helps to reduce the number of parameters of the model after the training phase without any significant loss of estimation accuracy. Nevertheless, the proposed architecture remains sufficiently general to provide a wide range of models among the most encountered in the literature. This reduction, achieved by a convenient choice of the activation functions and the initial conditions of the synaptic weights, is developed in two steps. The first step is to train the proposed architecture under two reasonable assumptions. Then the recurrent three-layers neural network is transformed into a representation of two-layer with less number of neurons, that is, a significant reduced number of parameters. The constructed architecture provided models with reasonable reduced number of parameters with a convenient estimation accuracy. To validate the proposed approach, we identify the Wiener-Hammerstein benchmark nonlinear system proposed in SYSID2009 [1]. © 2012 Elsevier B.V.

Alvarado-Juarez R.,CENIDET | Xaman J.,CENIDET | Alvarez G.,CENIDET | Hernandez-Lopez I.,CENIDET | Hernandez-Lopez I.,Zacatepec Institute of Technology
Desalination | Year: 2015

The numerical study of double-diffusive natural convection in an inclined rectangular cavity, that simulates a solar still, is carried out. Surface thermal radiation and heat conduction in a glass cover are considered. The study analyzes the effect of the glass cover, the aspect ratio (5≤A≤20) and the tilt angle (15°≤θ≤35°). The value of A is related to the Rayleigh number. The values analyzed were 9.29×104≤Ra≤6.56×106, where the minimum value of Ra corresponds to A=20 and the maximum value of Ra corresponds to A=5. Streamlines, isotherms, iso-concentration of H2O, condensate of H2O and Nusselt and Sherwood numbers are presented. Results show that the energy transmitted through the glass cover causes asymmetry, increases the velocity near the walls, and modifies the flow pattern, and the heat and mass transfer. When A decreases, the multi-cell pattern decreases, and the convective heat and mass transfer increase up to 41%. As the tilt angle increases, the Sherwood and Nusselt numbers increase up to 3.8% and the condensate of water increases about 3% when the one-cell pattern prevails; when the multi-cell pattern decreases from θ=15° to θ=20° the Sherwood and Nusselt numbers decrease up to 22% and the condensate of water decreases up to 43%. © 2014 Elsevier B.V.

Alvarado-Juarez R.,CENIDET | Alvarez G.,CENIDET | Xaman J.,CENIDET | Hernandez-Lopez I.,CENIDET | Hernandez-Lopez I.,Zacatepec Institute of Technology
Desalination | Year: 2013

Double-diffusive natural convection and surface thermal radiation in an inclined cavity that simulates a solar still device is studied numerically. The parameters considered were 103≤RaT (RaM)≤106, 8≤A≤16 and 15°≤θ≤35°. The steady state 2-D governing equations have been solved by the finite volume method. Streamlines, isotherms, isolines of water vapor, mass flow rate of distillate and average Nusselt and Sherwood numbers as a function of Rayleigh number for different inclination angle are presented. The results show that surface thermal radiation modifies the fluid flow from one-cell to multi-cellular pattern due to the surface thermal radiation increases the velocity near the walls, as a consequence the average convective Nusselt number, the total Nusselt number and the Sherwood number were increased about 25%, 175% and 15%, respectively. The mass flow rate of distillate increases as A, Ra and θ increase. The most suitable case for a solar still device is that for RaT=106, A=16 and θ≤25°. © 2013 Elsevier B.V.

Villa-Corrales L.,CENIDET | Flores-Prieto J.J.,CENIDET | Xaman-Villasenor J.P.,CENIDET | Garcia-Hernandez E.,Zacatepec Institute of Technology
Journal of Food Engineering | Year: 2010

A theoretical and experimental study for the drying kinetics of Ataulfo mango slices was carried out. In the study different thicknesses, air drying temperature, maturity degree and non-isotropic mass diffusion were considerate. The 2D temperature and moisture distributions inside the slice were predicted by using a theoretical model. The water effective diffusion coefficient, the convective heat and mass transfer coefficients, the drying curves and the center temperature were getting by the experimental model. A parametric study was carried out in the ranging of air drying temperatures from 50 to 70 °C, slices with thickness of 2-5 mm and maturity degree from 13.2 to 22°Brix. It was found from the experimental results that slices of Ataulfo mango present an isotropic behavior with an uncertainty of 2.47%. The drying rate reduces in 4.5% as 1 mm thickness increase, and decreases in 8.0% for each 1°Brix increased. © 2010 Elsevier Ltd. All rights reserved.

Cazarez-Candia O.,Mexican Institute of Petroleum | Cazarez-Candia O.,Zacatepec Institute of Technology | Benitez-Centeno O.C.,National Research Center y Desarrollo Tecnologico | Espinosa-Paredes G.,Metropolitan Autonomous University
International Journal of Heat and Fluid Flow | Year: 2011

In this work it is presented a transient, one-dimensional, adiabatic model for slug flow simulation, which appears when liquid (mixture of oil and water) and gas flow simultaneously through pipes. The model is formed by space and time averaged conservation equations for mass, momentum and energy for each phase, the numerical solution is based on the finite difference technique in the implicit scheme. Velocity, pressure, volumetric fraction and temperature profiles for both phases were predicted for inclination angles from the horizontal to the vertical position (unified model) and ascendant flow. Predictions from the model were validated using field data and ten correlations commonly used in the oil industry. The effects of gas heating or cooling, due to compression and expansion processes, on the predictions and numerical stability, were studied. It was found that when these effects are taken into account, a good behavior of temperature predictions and numerical stability are obtained. The model presents deviations lower than 14% regarding field data and it presents better predictions than most of the correlations. © 2011 Elsevier Inc.

Gomez V.,Zacatepec Institute of Technology | Garrido S.E.,Instituto Mexicano Of Tecnologia Del Agua
One Century of the Discovery of Arsenicosis in Latin America (1914-2014): As 2014 - Proceedings of the 5th International Congress on Arsenic in the Environment | Year: 2014

Arsenic (As) is particularly known for its toxic effect, especially due to its carcinogenic action and significant effects on the skin. Food and water are the primary sources of ingesting As. The search for low-cost adsorbents that are easily available has led to investigations on organic materials. Thus, a bioadsorbent medium was developed to remove arsenic from water for human consumption, using orange albedo coated with Fe(III). The bioadsorbent medium had a surface area of 0.0216 m2 g-1 for the case of uncoated pectin and 0.0894 m2 g-1 for pectin coated with Fe(III) ions. The active groups present in the surface of the solid adsorbent were identified using infrared spectroscopy with Fourier Transform (FTIR). A composition analysis was conducted by X Ray Diffraction (XRD) and sweep electronic microscopy. Adsorption capacity obtained was 0.5498 g mg-1 min-1 for Fe(III)-coated pectin. © 2014 Taylor & Francis Group.

Sanchez-Rivera M.M.,National Polytechnic Institute of Mexico | Almanza-Benitez S.,Zacatepec Institute of Technology | Bello-Perez L.A.,National Polytechnic Institute of Mexico | Mendez-Montealvo G.,National Polytechnic Institute of Mexico | And 3 more authors.
Carbohydrate Polymers | Year: 2013

The effect of iodine concentration on the acetylation of starches with low and moderate degree of substitution (DS < 0.5) and its impact on the physicochemical feature and structural features was evaluated. The acetylated starches were prepared with 0.03 mol anhydroglucose unit, 0.12 mol of anhydride acetic, and 0.6, 0.9 or 1.4 mM of molecular iodine as catalyst in a sealed Teflon vessel using microwave heating (600 W/2 min). Pasting profile and rheological properties were obtained under steady flow; dynamic oscillatory test was used. Structural features were obtained by HPSEC-RI. In acetylated starches, DS and acetyl groups increased when the iodine concentration increased, corn starch showed higher values than banana starch. The viscosity of acetylated starches decreased relative to unmodified starches while, acetylated corn starch had lower value than acetylated banana starch. In the flow curves, a non-Newtonian pattern (shear-thinning) was shown in the pastes of native and modified starches. Storage modulus (G') and loss modulus (G") showed low dependence on frequency (G' α ω0.1; G" α ω0.2) on frequency sweep test, which is characteristic of a viscoelastic gel. Debranched native banana and corn starches presented trimodal chain-length distribution. The pattern was maintained in the acetylated starches, but with different level of short and long chains. The structural differences in native and acetylated samples explain the rheological characteristics in both starches. © 2012 Elsevier Ltd.

Zamudio-Flores P.B.,National Polytechnic Institute of Mexico | Torres A.V.,Zacatepec Institute of Technology | Salgado-Delgado R.,Zacatepec Institute of Technology | Bello-Perez L.A.,National Polytechnic Institute of Mexico
Journal of Applied Polymer Science | Year: 2010

Banana starch was oxidized at three different levels and afterwards acetylated. The double-modified starch was used for film preparation with the addition of chitosan. The physical, mechanical, and barrier properties were tested. The oxidation level increased the moisture content of the film, but the acetylation and the addition of chitosan decreased this characteristic. The oxidation level increased the whiteness of the film, but the second modification (acetylation) and the addition of chitosan to the blend did not affect this parameter. The solubility increased with the temperature and the oxidation level but decreased with the storage time of the film. The oxidation increased and the acetylation reduced the solubility with respect to the native starch film. The dual modification produced a solubility value less than that of its oxidized counterpart, and the addition of chitosan produced the highest solubility value. The addition of chitosan increased the tensile strength of the film, and the effect was higher with the oxidation level and longest storage time. The addition of chitosan produced a higher elongation value than that of its double-modified film, but at the longest storage time, this parameter decreased. The water vapor permeability increased with the oxidation level because of the hydrophilic character, but the acetylation reduced this parameter because the acetylation increased the hydrophobic character of the starch due to the ester group. Films prepared with the double-modified banana starch and the addition of chitosan had some improved physical, mechanical, and barrier properties, and they may be used in specific applications. © 2009 Wiley Periodicals, Inc.

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