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120440 results, page 1 of 10

EVALUACIÓN DE LAS COMPETENCIAS EN EL MANEJO DE LAS TECNOLOGÍAS DE INFORMACIÓN Y COMUNICACIÓN DE LOS DOCENTES EN EL ÁREA DE LAS CIENCIAS BIOMÉDICAS

JOSE ALFREDO ACOSTA FAVELA Jesus Rodarte Rene Noriega (2015)

Dentro de las instituciones educativas existimos profesionistas insertados en la docencia, sin los suficientes conocimientos filosóficos, pedagógicos y tecnológicos necesarios para vincularlos con el proceso de enseñanza aprendizaje, de tal manera que no existe una formación docente uniforme, con las competencias básicas para la enseñanza en la educación superior. Esta investigación tiene como objetivo principal, evaluar el dominio de las Competencias en el Manejo de las Tecnologías de Información y Comunicación (CMTIC´s) de los docentes del área de las ciencias biomédicas, que serán resultantes de un análisis situacional por medio de un cuestionario de autoevaluación aplicado de forma aleatoria a los docentes.

Article

Artículo

INGENIERÍA Y TECNOLOGÍA; MEDICINA Y CIENCIAS DE LA SALUD Competencias; Docentes, TICs INGENIERÍA Y TECNOLOGÍA MEDICINA Y CIENCIAS DE LA SALUD

Evaluación de la actividad citotóxica de limonoides de semillas de cítricos extraídos con co2 supercrítico

GUSTAVO CASTILLO HERRERA (2015)

En el proceso de industrialización de los cítricos se obtienen semillas como subproducto, éstas contienen limonoides, que están relacionadas con el amargor de los cítricos, además muestran bioactividades interesantes como anticancerígenos, antivirales y antitumorales. Para la obtención de limonoides existe un proceso definido mediante solventes y con extracción tipo shoxhlet, pero no existe un proceso optimizado. Por lo que el objetivo de este trabajo fue evaluar como se afecta de citotoxicidad de extractos de semillas de Citrus aurantifolia swingle, Citrus sinesis y Citrus reticulata utilizando dos tipos de solventes (metanol y acetona) y dos tiempos de extracción (5 y 8 horas) sobre linfoblastos in vitro de L5178Y encontrando la semilla de mayor citotoxicidad para evaluar en un proceso innovador de extracción como la extracción supercrítica.

Doctoral thesis

INGENIERÍA Y TECNOLOGÍA

Monitoring lipase/esterase activity by stopped flow in a sequential injection analysis system using p-nitrophenyl butyrate

Enrique J Herrera López (2015)

Lipases and esterases are biocatalysts used at the laboratory and industrial level. To obtain the maximum yield in a bioprocess, it is important to measure key variables, such as enzymatic activity. The conventional method for monitoring hydrolytic activity is to take out a sample from the bioreactor to be analyzed off-line at the laboratory. The disadvantage of this approach is the long time required to recover the information from the process, hindering the possibility to develop control systems. New strategies to monitor lipase/esterase activity are necessary. In this context and in the first approach, we proposed a lab-made sequential injection analysis system to analyze off-line samples from shake flasks. Lipase/esterase activity was determined using p-nitrophenyl butyrate as the substrate. The sequential injection analysis allowed us to measure the hydrolytic activity from a sample without dilution in a linear range from 0.05–1.60 U/mL, with the capability to reach sample dilutions up to 1000 times, a sampling frequency of five samples/h, with a kinetic reaction of 5 min and a relative standard deviation of 8.75%. The results are promising to monitor lipase/esterase activity in real time, in which optimization and control strategies can be designed

Article

monitoring; lipase/esterase activity; sequential injection analysis; stopped flow; p-nitrophenyl esters INGENIERÍA Y TECNOLOGÍA

Selección de microalgas a partir de agua eutrofizada de Guadalajara, medición de crecimiento y ciantificación de lípidos.

CRISTOBAL CAMARENA BERNARD (2013)

El objetivo de este trabajo fue aislar especies de microalgas nativas a partir de ambientes eutrofizados de Guadalajara Jalisco, para evaluar su cinética de crecimiento y determinar la concentración de lípidos a partir del uso de agua residual tratada como medio de cultivo. Se realizaron colectas en tres puntos cercanos a Guadalajara reconocidos por su alto nivel de contaminación y se aislaron las microalgas que mejor y más rápido respondieron al cultivo en laboratorio. De este aislamiento se obtuvieron 4 especies que fue con las que se realizó el trabajo. Chlorella vulgaris, Chlorella saccarophila, Scenedesmus dimosphus y Chlamydomonas gloeopara

Master thesis

INGENIERÍA Y TECNOLOGÍA

Mathematical modeling of coffee bean roasting in a novel spouted multistage system

GUADALUPE MARIA GUATEMALA MORALES (2015)

Background: Arriola[1] has developed a novel spouted bed multistage system that has several advantages over previous designs.

It has a novel configuration without dead zones or moving parts, hydrodynamic stability, scale up advantages, operation and

control simplicity, low pressure drop, very simple column start-up and shutdown procedures/conditions, continuous withdrawal

of solids from the bottom stage through an “S-valve” [2], and intense and controlled air-grain contact. This system

can be used for heat and mass transfer, as well as chemical reaction processes [1], such as coffee roasting. To describe the process

it is necessary to develop a mathematical model that takes into account not only the transport phenomena (or/and chemical

reaction), but also considers the contact scheme in the system [3].

Aim: The focus of this project is to develop a mathematical model that describes the coffee bean roasting process in a vertical

multistage spouted bed system designed by Arriola[1].

Method: The main component lost during the roasting process is water; a drying model of the process was considered appropriate.

Fick’s equation was solved, and the results were combined with the RTD (Residence Time Distribution) function selected

by Arriola[4], which comprises a compartment model of two flow regimes (plug and mixed). The model was fitted to the moisture

kinetics obtained from experimental runs where a 3-stage column was used. Airflow and temperature were 110 L/min and

450°C, and the solids flow was varied between 1.9 x10-3 and 7.5 x10-3 kg/s.

Results: Drying kinetics obtained by Fick’s equation, where an effective diffusion coefficient was estimated (Deff = 2.45 x

10-8 m2/sec), fitted experimental data fairly well (R2 = 0.95). Using this model and the RTD, we estimated the number of stages

needed and the corresponding tp (plug flow average residence time) and tM (mixed flow tank average residence time), for drying

from initial moisture content to a final average moisture content. Results found indicate that in order to reach moisture content

of 7%, a column of 10 stages should be used, and the values of tp and tM are 30.95% and 69.05, respectively.

Conclusions: Fick’s equation combined with the RTD function generated an adequate model to predict the average

moisture of the roasted coffee beans at the exit of the multistage spouted bed system.

Conference poster

mathematical modeling, multistage system, coffee bean roasting, hydrodynamic stability INGENIERÍA Y TECNOLOGÍA

Modelo empírico para el cambio en la coloración del café durante el tostado en un sistema de lechos fuente en multietapa

GUADALUPE MARIA GUATEMALA MORALES (2013)

La clave del café de mejor calidad está en el proceso de tostado. Durante este proceso los

cambios en la coloración son evidentes y se deben principalmente a la descomposición

térmica y la pirólisis de los compuestos orgánicos acompañada de destilación seca. A fin de

producir una bebida de calidad es importante que el tostado se realice de la manera correcta

y uniforme. Por otra parte, el sistema de lechos fuente en multietapa presenta un buen

mezclado y un contacto efectivo fluido-partícula, que posibilita el uso de aire de

calentamiento a altas temperaturas, proporcionando un producto tostado uniforme y limpio

(Guatemala 2007). En el presente trabajo se desarrolló un modelo empírico para describir,

dentro del rango de operaciones utilizado, el comportamiento del cambio en la coloración

respecto al tiempo (t) y a la temperatura del aire (TA). Para tal efecto se llevaron a cabo

experimentos utilizando temperaturas del aire de tostado de 400-500 °C. Para medir la

coloración del café se utilizó el espacio de color CIE 1976 L*a*b* (iluminante D65 y

observador patrón a 10°). De los tres parámetros probados, sólo la luminosidad, L*,

presentó un comportamiento definido a través de las diferentes temperaturas de aire. Los

resultados experimentales mostraron que, para este sistema, la temperatura de inicio de

tostado se encuentra cuando la temperatura del grano es de l86 °C. El modelo desarrollado

dentro intervalo experimentado representa a los datos en un 95%.

Conference proceedings

lechos fuente; tostado de café; modelo empírico; color. INGENIERÍA Y TECNOLOGÍA

Tensile Properties of Thermoplastic-Laminated Composites Based on a Polypropylene Matrix Reinforced with Continuous Twaron Fibers

PEDRO IVAN GONZALEZ CHI (2013)

The present paper focuses on a semiempirical macroscopic

approach for the prediction of the tensile properties (modulus and strength) of

thermoplastic laminates based on polypropylene (PP) reinforced with Twaron

fibers. The influence of fiber content on the orthotropic stiffnesses and strengths

of the unidirectional composite was experimentally determined; then, these

orthotropic properties were the input data for the prediction, by means of the

classical lamination theory, of the tensile effective properties of several

PP/Twaron laminates. Good agreement was found between the predicted and

experimental tensile data of the laminates.

Article

INGENIERÍA Y TECNOLOGÍA

Membranes from rigid block hexafluoro copolyaramides: Effect of block lengths on gas permeation and ideal separation factors

MANUEL DE JESUS AGUILAR VEGA (2013)

Dense membranes were prepared from three different rigid block copolyaramides, one block bearing two

bulky hexafluoro (–CF3) groups and a lateral tert-butyl group (–C–(CH3)3), and the second block without

the lateral tert-butyl group. The effect of block length, at constant comonomer concentration, on thermal

properties as well as gas permeability coefficients and separation factors is analyzed. The results indicate

that block copolyaramide membranes present a density that is quite similar but slightly lower, as the

length of the blocks that form the copolymer increase, that falls in between the density of the

homopolyamides. The fractional free volume, FFV, increases in the block copolymers as the block length

increases. This result is attributed to an inefficient packing of the copolymer molecules as the block

length gets larger. As a result, the permeability and diffusion coefficients in the block copolymers are

larger than those in the parent homopolymers. The gas separation factors remain with a minimum

change even though there is a gain in gas permeability; therefore, block copolymerization using highly

rigid blocks, due to differences in packing, presents the advantage of a higher gas permeability coefficient

with a minimum loss in selectivity. The rigidity of these copolymers presents advantages for high

temperature applications.

Article

INGENIERÍA Y TECNOLOGÍA

Tensile piezoresistivity and disruption of percolation in singlewall and multiwall carbon nanotube/polyurethane composites

FRANCIS AVILES CETINA (2013)

Carbon nanotube elastomeric composite films were fabricated by solution casting using singlewall

and multiwall carbon nanotubes (SWCNTs and MWCNTs) and two thermoplastic-elastomers polymer

matrices, an in-house synthesized segmented polyurethane and a commercial one. The CNTs are first

characterized and the electrical conductivity, mechanical properties and piezoresistive response of the

SWCNT and MWCNT composites with 8 wt% are evaluated. For both polymer matrices, the electrical

conductivity of composites made from MWCNTs is higher than that achieved for composites made from

SWCNTs. Evaluation of the strain–electrical resistance relationship of the composites shows a dependency

of the piezoresistive sensitivity on the kind of CNT (SWCNT or MWCNT) and matrix electrical and

mechanical properties. Above a specific strain threshold, electrical percolation is disrupted under tensile

loading. The strain level at which this happens is larger for composites made with MWCNTs than for

composites made with SWCNTs.

Article

INGENIERÍA Y TECNOLOGÍA