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Search Results: 1 - 10 of 432323 matches for " F.;Sánchez-Rivera "
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Some intrinsic and extrinsic factors of acetylated starches: morphological, physicochemical and structural characteristics
Nú?ez-Santiago, M.C.;García-Suárez, F.J.;Gutierrez-Meraz, F.;Sánchez-Rivera, M.M.;Bello-Pérez, L.A.;
Revista mexicana de ingeniería química , 2011,
Abstract: degree substitution (ds), morphological characteristics, x-ray diffraction (xrd), pasting properties, thermal properties and amylopectin chain length distribution were used to study the effect of botanical source (potato starch, ps; and maize starch, ms) and reagent type (acetic anhydride and vinyl acetate) on starch acetyration. the reagent type produced a different effect depending on the botanical source: for ms, the reaction with acetic anhydride produced higher ds than ps, whereas that in the reaction with vinyl acetate resulted in an inverse pattern. in general, modified starches had a maltase cross, except for ps when acetylated with acetic anhydride. native ps had the highest crystallinity level and trie acetylated starches had a decreased amount of crystallinity (between 10% and 12 %) compared to the native starches. acetylation produced a decrease in pasting temperature, and changes in the pasting characteristics were more evident wish higher ds. structural changes in starch components due to the acetylation reaction produced a decrease in the temperature and enthalpy of gelatinization. in general, acetylated starches had minor retrogradation. regardless of reagent used, acetylated ms had higher retrogradation than acetylated ps. higher ds values resulted in greater amounts of short chains in both starches.
Efecto de la temperatura en la reacción de oxidación del almidón de plátano (Musa paradisiaca L. ). estimación de la energía de activación
Sánchez-Rivera, M. M.;Bello-Pérez, L. A.;
Revista mexicana de ingeniería química , 2008,
Abstract: native banana (musa paradisiaca l.) starch was subjected to oxidation with sodium hypochlorite (naclo) at 2 % of active chlorine (p/v) at different temperatures (30, 40 and 50 °c) and two ph (7.0 and 8.5). the rate constants (k) and the activation energy (ea) were obtained from the concentration of hypochlorite clo-, (expressed as chlorine consumption) during the starch oxidation. first and second order equations were used to determine the reaction order, considering the initial concentrations of the starch [a]0 = 2.134 moles/l and the oxidant agent [b]0= 140.84 mmoles/l. as the temperature increased and at 40 minutes of reaction, practically all chlorine was consumed and in major amount at ph 8.5, obtaining values near to 20 mg cl2 / g of starch. more than 75 % of chlorine reacted during the five minutes, presumably with the starch pigments. the data were fit for a first order reaction and the reaction rate was higher at ph 7.0 than at 8.5, and it increased when temperature increased. the results allowed the calculation of the ea of 66.481 kj/mol (ph 8.5) and 51.082 kj/mol (ph 7.0).
Nicaraguan population data on LDLR, GYPA, D7S8, HBGG, GC and HLA-DQA1 loci
Bernal Morera,Gerardo Sánchez-Rivera,Gerardo Jiménez-Arce,Francesc Calafell
Revista de Biología Tropical , 2001,
Abstract: Nicaraguans have become the most numerous and fastest increasing minority in Costa Rica: at present they represent around 6 % of the total population of the country. We have analyzed the allele and genotype frequencies of six PCR-based genetic markers (LDLR, GYPA, HBGG, D7S8, GC, and HLA-DQA1) in 100 unrelated Nicaraguans living in Costa Rica. All loci studied were in Hardy-Weinberg equilibrium. Some statistical parameters of forensic interest were also calculated (h, PD and CE). Allele frequencies of the markers HLA-DQA1 and GYPAwere found to be significantly different between the populations of Nicaragua and Costa Rica. Nevertheless, genetic distances showed that Nicaragua is close to other Hispanic-admixed populations like those from Argentina, Chile, Colombia, Costa Rica, and USA Hispanics. The loci set was assessed to be useful for paternity testing and individual identification in the Nicaraguan population residing in Costa Rica Los nicaragüenses se han convertido en el grupo minoritario más numeroso y creciente en Costa Rica y en la actualidad representan alrededor del 6 % de la población total del país. Analizamos las frecuencias alélicas y genotípicas de seis marcadores genéticos (LDLR, GYPA, HBGG, D7S8, GC y HLA-DQA1) basados en la PCR en 100 nicaragüenses no emparentados, residentes en Costa Rica. Todos los loci estudiados cumplieron con el equilibrio de Hardy-Weinberg. También se calcularon algunos parámetros estadísticos de interés forense (h, PD y EC). Se encontró que las frecuencias alélicas de los marcadores HLA-DQA1 y GYPA presentan diferencias significativas entre las poblaciones de Nicaragua y Costa Rica. Sin embargo, el análisis de distancias genéticas mostró que la población de Nicaragua es cercana a otras de origen hispano mestizo como las poblaciones de Argentina, Chile, Colombia, Costa Rica y los hispanos de Estados Unidos. Este conjunto de loci fue validado como útil para la realización de pruebas de paternidad y para la identificación de individuos en la población nicaragüense residente en Costa Rica
Morphometric, Physicochemical, Thermal, and Rheological Properties of Rice (Oryza sativa L.) Cultivars Indica × Japonica  [PDF]
Laura Elizabeth Morales-Martínez, Luis Arturo Bello-Pérez, Mirna María Sánchez-Rivera, Elsa Ventura-Zapata, Antonio Ruperto Jiménez-Aparicio
Food and Nutrition Sciences (FNS) , 2014, DOI: 10.4236/fns.2014.53034
Abstract:

The anther culture technical was applied to produce haploid lines of rice (Oryza sativa L.). The hybrids (K/ A92VM061, K/A92VM067, K/A92VM0611, K/A92VM719, K/A92VM720 and K/A92VM721) were obtained in order to generate new varieties from Indica and Japonica cultivars. Morphometric parameters of the grains were evaluated by image analysis. Flours were prepared from the whole rice grains and physicochemical, thermal and rheological properties, X-ray diffraction pattern and evaluation of color using the CIELAB system were assessed. The hybrids lines showed long (061, 611, 721), medium (719 and 720) and short (067) grains. The rice samples presented lipids (2.6% - 3.2%), protein (11% - 15%), total dietary fiber (8.4% - 10.2%), total starch (65% - 74%) and apparent amylose (5% - 32%) contents. Gelatinization temperature (Tp) was found in the range of 66.1℃ - 79.4℃ with enthalpy (ΔH) value between 3.4 - 8.1 J/g. The retrogradation parameters (temperature and ΔH) were lower than those for gelatinization in all samples. The rice samples presented A-type X-ray diffraction pattern. Rice pastes showed a non-Newtonian behavior and the brightness (L*) characterize the color of the samples. Hybrid rice grains presented morphometric properties more similar to Japonica than Indica variety. Rice hybrid had higher protein content than Indica variety. Apparent amylose, viscosity and gelatinization temperature varied significantly among hybrids and varieties.

Nicaraguan population data on LDLR, GYPA, D7S8, HBGG, GC and HLA-DQA1 loci
Morera,Bernal; Sánchez-Rivera,Gerardo; Jiménez-Arce,Gerardo; Calafell,Francesc; Morales-Cordero,Ana Isabel;
Revista de Biología Tropical , 2001,
Abstract: nicaraguans have become the most numerous and fastest increasing minority in costa rica: at present they represent around 6 % of the total population of the country. we have analyzed the allele and genotype frequencies of six pcr-based genetic markers (ldlr, gypa, hbgg, d7s8, gc, and hla-dqa1) in 100 unrelated nicaraguans living in costa rica. all loci studied were in hardy-weinberg equilibrium. some statistical parameters of forensic interest were also calculated (h, pd and ce). allele frequencies of the markers hla-dqa1 and gypawere found to be significantly different between the populations of nicaragua and costa rica. nevertheless, genetic distances showed that nicaragua is close to other hispanic-admixed populations like those from argentina, chile, colombia, costa rica, and usa hispanics. the loci set was assessed to be useful for paternity testing and individual identification in the nicaraguan population residing in costa rica
Effect of chemical modification type on physicochemical and rheological characteristics of banana starch
Guerra-DellaValle, D.;Sánchez-Rivera, M. M.;Zamudio-Flores, P. B.;Méndez-Montealvo, G.;Bello-Pérez, L. A.;
Revista mexicana de ingeniería química , 2009,
Abstract: isolation of non-conventional starches has increased in the last decade; chemical modification of these no conventional starches may produce starches with improved physicochemical and functional properties that are not available from commercial starches. banana starch was acetylated and oxidized and the thermal, pasting and rheological characteristics were evaluated. the low carbonyl and carboxyl groups might be due to the starch source. the acetylated banana starch obtained had a low degree of substitution (0.04). the acetylated banana starch had lower temperature and enthalpy of gelatinization than oxidized and native banana starches, had higher peak viscosity in the viscoamylographic profile than its native counterpart. the oxidized starch produced the peak viscosity during the cooling step and the three starches had higher viscosity during the cooling step, showing a gel conformation. the native, acetylated and oxidized starches showed a non-newtonian behavior of the shear-thinning type. the rotational test showed that oxidized banana starch had a firmer gel than acetylated starch, which agrees with the viscoamylographic results.
Caracterización morfológica, molecular y fisicoquímica del almidón de plátano oxidado y lintnerizado
Rivas-González, Mayra;Méndez-Montealvo, M. Guadalupe C.;Sánchez-Rivera, Mirna M.;Nú?ez-Santiago, M. Carmen;Bello- Pérez, Luis A.;
Agrociencia , 2008,
Abstract: a morphological, molecular and physicochemical characterization was made of the starch extracted from the banana (musa paradisiaca l.), chemically modified by oxidation and by lintnerization. native banana starch was used as reference. the modification level was evaluated through polarized light microscopy, x-ray diffraction, infrared spectroscopy and the viscoamylographic profile. the oxidized starch presented a substitution degree of 0.13 and 0.03% of carbonyl and carboxyl groups. the native and modified starches presented the maltese cross (birefringence) indicating a crystalline organization. the three starches presented diffraction pattern between a- and b-types. infrared spectroscopy revealed the presence of a high level of organization within the granules: 1.678, 1.689 and 1.883 for the native, oxidized and lintnerized starches. there were no differences (p>0.05) in the viscosity profile of the native and oxidized starches, whereas the lintnerized starch presented lower values due to a probable hydrolysis provoked during the modification. the lintnerized starch also presented the least changes in its enthalpies (δh) of gelatinization and retrogradation, suggesting the formation of smaller and more imperfect crystals. the characterization made on the modified banana starches could suggest their possible industrial applications.
Inflammation, Oxidative Stress, and Obesity
Alba Fernández-Sánchez,Eduardo Madrigal-Santillán,Mirandeli Bautista,Jaime Esquivel-Soto,ángel Morales-González,Cesar Esquivel-Chirino,Irene Durante-Montiel,Graciela Sánchez-Rivera,Carmen Valadez-Vega,José A. Morales-González
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12053117
Abstract: Obesity is a chronic disease of multifactorial origin and can be defined as an increase in the accumulation of body fat. Adipose tissue is not only a triglyceride storage organ, but studies have shown the role of white adipose tissue as a producer of certain bioactive substances called adipokines. Among adipokines, we find some inflammatory functions, such as Interleukin-6 (IL-6); other adipokines entail the functions of regulating food intake, therefore exerting a direct effect on weight control. This is the case of leptin, which acts on the limbic system by stimulating dopamine uptake, creating a feeling of fullness. However, these adipokines induce the production of reactive oxygen species (ROS), generating a process known as oxidative stress (OS). Because adipose tissue is the organ that secretes adipokines and these in turn generate ROS, adipose tissue is considered an independent factor for the generation of systemic OS. There are several mechanisms by which obesity produces OS. The first of these is the mitochondrial and peroxisomal oxidation of fatty acids, which can produce ROS in oxidation reactions, while another mechanism is over-consumption of oxygen, which generates free radicals in the mitochondrial respiratory chain that is found coupled with oxidative phosphorylation in mitochondria. Lipid-rich diets are also capable of generating ROS because they can alter oxygen metabolism. Upon the increase of adipose tissue, the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), was found to be significantly diminished. Finally, high ROS production and the decrease in antioxidant capacity leads to various abnormalities, among which we find endothelial dysfunction, which is characterized by a reduction in the bioavailability of vasodilators, particularly nitric oxide (NO), and an increase in endothelium-derived contractile factors, favoring atherosclerotic disease.
Enfermedad celíaca y nefropatía membranosa
Soro,S.; Sánchez de la Nieta,M.; Rivera,F.;
Nefrología (Madrid) , 2009,
Abstract: celiac disease results from the interaction between gluten and immune, genetic, and environmental factors. although the main clinical manifestations are derived from gastrointestinal system, it has been described some renal diseases, especially chronic glomerulonephritis. we describe a young female patient with celiac disease which appears after delivery. moreover, she develops simultaneously nephrotic proteinuria and microhematuria as a result of membranous nephropathy. the treatment with gluten-free diet and other conservative measures (acei and statin) is followed by clinical improvement and simultaneous decrease of tissue antitransglutaminase iga-antibodies and complete remission of proteinuria. we review the relationship between celiac disease and membranous nephropathy and the role of diet in the management of both diseases.
Manejo Multidisciplinario del paciente diagnosticado con el Síndrome de Sj?gren
Rivera,H; Valero,L; Escalona,L; Roja-Sánchez,F; Ríos,MP;
Acta Odontológica Venezolana , 2009,
Abstract: sjogren syndrome (ss) is a chronic autoimmune exocrinopathy that primarily affects salivary and lacrimal glands. occasionally, could present extraglandular involvement. the most common oral findings include mucositis, glossitis, cheilitis, atrophic candidiasis and non specific chronic ulcers mainly produced by the severe decreased salivary flow rate. other manifestations include periodontal disease mainly gingivitis and cervical caries. a current review of the different modalities of treatment of the oral manifestations both local and systemic is presented for the first time. additionally, an updated multidisciplinary approach focused on periodontal, preventive and prosthetic is presented.
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