oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 10 )

2018 ( 47 )

2017 ( 48 )

2016 ( 63 )

Custom range...

Search Results: 1 - 10 of 26844 matches for " Jorge Abraham Tamayo Cortez "
All listed articles are free for downloading (OA Articles)
Page 1 /26844
Display every page Item
Extraction and Stability of Anthocyanins Present in the Skin of the Dragon Fruit (Hylocereus undatus)  [PDF]
María de Lourdes Vargasy Vargas, Jorge Abraham Tamayo Cortez, Enrique Sauri Duch, Andrés Pech Lizama, Carlos Hernán Herrera Méndez
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.412156
Abstract:

The extraction of anthocyanins present in the skin of the dragon fruit was performed using trifluoroacetic acid (TFA) plus a mixture of methanol, acetic acid and water; the anthocyanins were then purified with a LC-18 cartridge, using methanol acidified with TFA as eluent, reaching concentrations of 44.3865 ± 1.3125 mg/100g of sample. The extracts were put through stability tests under different storage conditions, modifying the pH of the extracts (pH of 1, 4 and 6), the temperature (4℃, 25℃ and 68℃) and the absence and presence of light for a time period of 4 days; the tests indiated that anthocyanins remain more stable at a temperature of 4℃ with a pH of 4 in the absence of light, retaining up to 80% of the pigment. Three anthocyanins were partially identified in the extracts by high performance liquid chromatography (HPLC); they were: cyanidin 3-O-glucoside, cyanidin 3,5 O-glucoside and pelargonidin 3,5 O-glucoside.

Identification and Quantification of Monosaccharides in Aloe vera Gel by Acid and Enzymatic Hydrolysis and Wet Heat Treatment  [PDF]
Dianeli Madera Pi?a, Carlos Hernán Herrera Méndez, Lourdes Vargas y Vargas, Herbert Loria Sunza, Jorge Tamayo Cortez
Food and Nutrition Sciences (FNS) , 2017, DOI: 10.4236/fns.2017.88060
Abstract: Aloe vera (Aloe barbadensis Miller) possesses curative and therapeutic properties attributed to the polysaccharides found in its tissue. This work aimed to study hydrolyzed (chemical and enzymatical) Aloe vera gel extracts using ultrafiltration membranes with a pore size of 0.22 micron (μm). Nine chemical treatments were achieved with H2SO4 and three wet heat treatments were carried out at a pressure of 1.2 lbf/in2 for 15 minutes; in both cases, three different concentrations of Aloe vera gel juice (AGJ) were used: 1.5%, 2.5% and 3.5% w/w. The concentrations of H2SO4 were 0.10%, 0.25% and 0.40% w/w. Chemical experiments are performed over a factorial 32 design and results were analyzed using SPSS software (version 17, SPSS Inc.), finding the one labeled T7 (15 ml of AGJ 3.5% with 15 ml of H2SO4 0.10% added) the best of them, as it leaded to 0.0446 mg/ml of liberated glucose. Among the three wet heat treatments, the one labeled TC3 (15 ml of AGJ 3.5% with 15 ml of H2O added) was the best-performing one, as it leaded to 0.292 mg/ml of liberated glucose. Furthermore, an enzymatic hydrolysis was carried out using Novozymes’ Pectinex? AR and Viscozyme?. Hydrolisis with both enzymes yield to better results than acid hydrolysis: in the treatment with Pectinex? AR, 3.282 mg/ml of liberated glucose were obtained and 3.302 mg/ml in the treatment with Viscozyme?. The hydrolyzed substances obtained by acid and enzymatic hydrolysis, as well as by wet heat treatment, were subsequently analyzed by thin layer chromatography (TLC), using glucose, galactose and arabinose 1000 ppm solutions as reference patterns. Among the treatments by H2SO4, the one labeled T4 obtained an Rf value of 50, the same as on the galactose reference pattern.
Purification and Partial Characterization of Polyphenol Oxidase from Sapodilla Plum (Achras sapota)  [PDF]
Jorge Tamayo Cortez, Carlos Hernán Herrera Méndez, Enrique Sauri Duch, María de Lourdes Vargas y Vargas, Sara Solís Pereira
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.47093
Abstract: The browning of fruits can be considered as an enzymatic oxidation which is believed to be one of the main causes of quality loss during post-harvest handling. The enzymes responsible for this are the oxidoreductases; the polyphenol oxidase (PPO) (monophenol, o-diphenol, oxygen oxidoreductase; EC 1.14.18.1) belongs to this group. This enzyme, which is found in the sapodilla plum (Achras sapota), was purified using a phenylsepharose and a SephacrylS-200 columns. The molecular weight of the purified enzyme was estimated to be about 66 kDa by gel filtration and 29 kDa by SDS-PAGE. A single protein band was found using the latter system (SDS-PAGE), which shows that the PPO of the pulp of the sapodilla plum may be composed of two protein subunits with similar molecular weight. The optimum pH was 7.0 and the optimum temperature 60. The most effective inhibitors tested were ascorbic acid, sodium metabisulfite and acetic acid.
Main Polysaccharides Isolated and Quantified of Aloe vera Gel in Different Seasons of the Year  [PDF]
Berenice Aranda Cuevas, Carlos Hernán Herrera Méndez, Ignacio Islas Flores, Sara Solís-Pereira, Luis Cuevas-Glory, Gerardo Rivera Mu?oz, María de Lourdes Vargas y Vargas, Jorge Tamayo Cortez
Food and Nutrition Sciences (FNS) , 2016, DOI: 10.4236/fns.2016.76046
Abstract: We developed and implemented a methodology that allowed extracting and evaluating high molecular weight polysaccharides present in the gel of Aloe barbadensis Miller. One of the fractions evaluated revealed the presence of high molecular weight carbohydrates (200 kDa) with a behavior similar to that of acemannan and another fraction with compounds of molecular weights between 17 and 47 kDa. We quantified the concentration of acemannan for two different growing periods. The concentration of acemannan in the high molecular weight fraction was 99.97 ppm in the rainy season and 106.03 ppm in the dry season. The concentration of acemannan in the fraction of low molecular weight was 9.364 ppm during the season of greatest rainfall and 26.939 ppm in the dry season.
Comportamiento de los materiales bajo carga repetida
Tamayo Tamayo Jorge
Ingeniería e Investigación , 1985,
Abstract: Este es un trabajo presentado al V Simposio Colombiano sobre Ingeniería de Pavimentos, realizado en Cúcuta en octubre de 1983.
Mejoramiento del comportamiento de suelos y materiales con la incorporación de aditivos no convencionales: evaluación preliminar
Tamayo Tamayo Jorge
Ingeniería e Investigación , 1985,
Abstract: Es muy poco lo que se puede hacer por conocer las características intrínsecas de los aditivos ya que se trata de productos de composición compleja sobre la cual existe reserva y no se proporciona ninguna información determinante; respecto al campo de aplicación, corre a cargo de los productores. En consecuencia la primera actividad a acometer es la evaluación y verificación de las propiedades y características de los materiales tratados. El objeto de este trabajo es el de presentar los primeros resultados de trabajos de evaluación y verificación que a manera de proyectos de grado se han realizado en el Laboratorio de Ensayo de Materiales de la Facultad de Ingeniería de la Universidad Nacional de Colombia, Bogotá.
Estudio de la incidencia de las propiedades índices en la calidad de las mezclas asfálticas
Tamayo Tamayo Jorge
Ingeniería e Investigación , 1983,
Abstract: EI comportamiento de las mezclas asfálticas depende fundamentalmente de las características que presenten, sus principales componentes: los agregados pétreos, dentro de estas características se destacan sus propiedades índices: granulometría, índices de forma y textura superficial, reflejados estos dos últimos en el índice de trituración, aunque no de una manera totalmente aceptable y contundente. Otras propiedades índices inciden igualmente en la calidad de las mezclas asfálticas pero no son analizadas en el presente escrito. Se presentan algunas consideraciones referidas a la selección adecuada de la granulometría ya la incorporación del índice de trituración como indicador básico en las evaluaciones preliminares de las fuentes materiales. Finalmente se presentan algunos resultados de un trabajo realizado sobre el mismo tema, a manera de proyecto de grado en la Universidad Nacional de Colombia.
Bases biológicas de la dependencia de las drogas: hacia un enfoque integral del proglema Biologic bases of drug dependence: toward an integral approach of the problem
Jorge Mario Tamayo
Iatreia , 1998,
Abstract: El abuso y la dependencia de las drogas son problemas complejos y costosos que requieren una intervención terapéutica polimodal e integral. En los últimos a os se han dado varios descubrimientos científicos relacionados con las bases biológicas de estos trastornos. Ello ha permitido desarrollar programas que incluyen el uso de diferentes psicofármacos y técnicas psicoterapéuticas que posibilitan una modulación de las vías neuronales disfuncionales. La investigación del sistema mesolímbico dopaminérgico y de los receptores opioides del tallo cerebral y del núcleo accumbens sumada al develamiento de los diferentes mecanismos intraneuronales, han permitido comprender me. jorlos cambios cerebrales ycomportamentales debidos al consumo agudo y crónico de drogas. Tales hallazgos biológicos son el propósito de esta revisión basada en una búsqueda de artículos a través de MEDLINE.. Drugs abuse and dependence are complex and expensive disorders that require a polymodal and integral therapeutic intervention. Several scientific discoveries related to the biological bases of these disorders have recently arisen. These discoveries guide the design of programs that include different psychotropic drugs and psychotherapeutic technics that allow a modulation of the neuronal dysfunction process. Research on the mesolimbic dopaminergic system and the opioid receptors in the brain stem and the nucleus accumbens added to new knowledge of different intraneuronal mechanisms, allow a better understanding of cerebral and behavioral changes due to acute and chronic consumption of drugs. Such biological findings are the purpose of this review based on a MEDLINE search of articles.
La modernización de la policía en la dictadura de Ibá ez. Funciones y tareas asignadas a la Policía a principios del siglo XX
Jorge Tamayo Cabello
Divergencia , 2012,
Abstract: El objetivo del presente trabajo es exponer las diferentes funciones y tareas asignadas a la policía a inicios del siglo XX, comparando las asignadas a Carabineros de Chile, en su fundación (1927), y las cumplidas por las entidades que antecedieron a dicha institución. De este modo, se buscó dilucidar cuáles siguieron cumpliendo los “nuevos” carabineros, y cuáles fueron desechadas o entregadas a otras entidades del Estado. Para ello se presto especial atención en el contexto dictatorial de la fundación de Carabineros de Chile, consultándose principalmente revistas y boletines institucionales de las policías para analizar los cambios y continuidades en las ideas directrices y los objetivos buscados por la policía en la época estudiada.
Al margen del III Congreso [Nacional] de Geografía. Resultados y finalidades de este importante evento cultural
Jorge L. Tamayo
Investigaciones geográficas , 2003,
Abstract:
Page 1 /26844
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.