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Search Results: 1 - 10 of 402416 matches for " Juan Manuel SáNCHEZ-Yá?EZ "
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MODELO EXPERIMENTAL DE DIFUSIóN DE BIOGáS EN RAíCES VEGETALES
Eduardo BALTIERRA-TREJO,Liliana MáRQUEZ-BENAVIDES,Juan Manuel SáNCHEZ-Yá?EZ
Revista internacional de contaminación ambiental , 2012,
Abstract: La digestión anaerobia (DA) de la fracción orgánica (FO) de los residuos sólidos urbanos (RSU) en los rellenos sanitarios (RESA), genera biogás que tiene efecto negativo sobre algunas de las plantas que ahí crecen. Sin embargo no existe metodología para evaluarla, ni información del da o del biogás sobre la fisiología vegetal. Es necesario un modelo que simule su difusión sobre el sistema radical de plantas para determinar con precisión el efecto del biogás en función de la concentración en el sitio de exposición. El objetivo de esta investigación fue dise ar un modelo experimental ex situ para analizar el efecto del biogás sobre las raíces de calabaza (Cucurbita pepo L.). Para ello se dise ó y construyó un sistema de simulación de la DA de la FO de los RSU que difunde biogás en un suelo, donde creció la calabaza. El efecto del biogás sobre esa planta se midió con las variables respuesta: porcentaje de germinación, peso fresco y seco foliar y radical. Los resultados mostraron que la difusión de biogás en el suelo artificial provocó la inhibición de la germinación de semillas de calabaza y su crecimiento a nivel de plántula en comparación con la misma planta sin exponer a biogás, que germinó y creció sin signos de estrés.
Microorganismos Benéficos Asociados a Meloidogyne incognita (Kofoid y White) Chitwood en Guayabo (Psidium guajava L.) de Calvillo, Aguascalientes, México
Gallegos-Morales, Gabriel;Cepeda-Siller, Melchor;Hernández-Castillo, Francisco Daniel;Acosta-Zamarripa, Ana María;Velásquez-Valle, Rodolfo;González-Gaona, Ernesto;Sánchez-Yánez, Juan Manuel;
Revista mexicana de fitopatología , 2009,
Abstract: the root-knot nematode species meloidogyne incognita was identified as the one species that parasites guava orchards in the calvillo region (aguascalientes, mexico). beneficent fungi and bacteria were isolated as well, associated to soil and roots collected from the cerro blanco, mesa grande, la labor and malpaso locations. twenty different meloidogyne sp., samples were identified taking adult female perinea pattern characteristics into account, as well as the male anterior region observation. the meloidogyne incognita species was identified in all the samples. the isolated beneficent microorganisms and associated to guava rhizosphere with a potential use in biological control, belong to the bacillus cereus, b. subtilis b. megaterium and paecilomyces farinosus species. furthermore, the rhabditis and mononchus soil nematodes were identified in the samples.
Role of the Zinc Nutritional Status on Main Physiological Bioindicators of the Pecan Tree  [PDF]
Angélica Anahí Acevedo-Barrera, Esteban Sánchez, Rosa María Yá?ez-Mu?oz, Juan Manuel Soto-Parra, ángel Lagarda-Murrieta, Vicente de Paul álvarez-Reyna, Eduardo Madero-Tamargo, Alejandro Moreno-Resendez
Agricultural Sciences (AS) , 2017, DOI: 10.4236/as.2017.812096
Abstract: The purpose of this study was to analyze the effect of Zn nutritional status on the content of pigments, nonstructural carbohydrates, foliage proteins and amino acids of the pecan tree, as possible bioindicators of Zn deficiency. The experimental design was completely random with three Zn nutritional statuses: Normal, Intermediate and Deficient, being selected considering visual symptomatology. On all three nutritional statuses, the concentration of photosynthetic pigments was determined as well as of total soluble proteins and amino acids. Obtained results indicate that Zn deficient nutritional status was characterized by minimum photosynthetic pigment, protein concentrations, maximum amino acid and nonstructural carbohydrate concentrations. While the normal Zn nutritional status presented maximum photosynthetic pigments, proteins concentrations, minimum amino acids and carbohydrate concentrations. On the other hand, intermediate Zn nutritional status was characterized by a medium level between the other two Zn nutritional statuses. Finally, we stress the fact that pigments, proteins, amino acids and nonstructural carbohydrates may be good physiological indicators related to Zn nutritional status on pecan trees.
Biomasa, actividad enzimática y compuestos nitrogenados en plantas de frijol ejotero bajo diferentes dosis de potasio
Sánchez Chávez, Esteban;Soto Parra, Juan Manuel;Ruiz Sáez, Juan Manuel;Romero Monreal, Luis;
Agricultura técnica en México , 2006,
Abstract: one of the main factors regulating biomass production, enzymatic activity and the amount of nitrogen compounds in roots and leaves of snap beans (phaseolus vulgaris l.) is the nutritional status of k, hence the objective of this research was to understand the effect of different potassium concentration on these physiological plant responses. the experiment was carried out with the snap bean cv. strike in growth chambers during the spring of 2000 in granada, spain. the controlled environment conditions were: relative humidity 60-80%, temperature 28/22 °c (day/night), photoperiod 16/8 h (day/night) and luminosity of 350 μmol m-2 s-1. potassium was applied as nutrient solution of koh in increasing concentrations: k1= 1.0 mm, k2= 2.0 mm, k3= 4.0 mm, k4= 8.0 mm, k5= 12.0 mm, and k6=16.0 mm of k+. results indicated that both deficiencies and excess of k affected the nitrogen metabolism in the same way that the effect caused by n stress. under k+ deficiencies (k1 and k2) there was a decrease in the content of enzymes related to n assimilation such as nitrate reducíase, nitrite reductase, glutamine sintetase, glutamine sintase, and phosphoenolpyruvate carboxylase, causing in the plant low concentrations of amino acids, proteins, nitrogen organic compounds, all of which diminished biomass production in 15% when compared to k3. treatments with higher concentrations of k+ such as k4, k5 and k6 had the greater concentrations of no3- and nh4+, increased assimilation of n and higher concentration of nitrogen compounds. however, these increments were not related to biomass, acummulation, on the contrary, dry weight of roots and shoots were diminished in 35% due to the toxic effects observed in treatments k5 and k6. therefore, k+ doses above the optimal were detrimental for root and shoot growth, being the shoot more diminished.
La Criptogamia: ciencia complemento de la Arqueología
López Sáez, José Antonio,Diez Fernández, Pedro Manuel,Sánchez Villapadierna, José Juan
Trabajos de Prehistoria , 1991,
Abstract: The importance that Cryptogamy might have as an auxiliar y source of Archaeology can be glimpsed from the large amount of data of criptogamic plants in ecological and palinological studies. The relation between these kind of plants and man has been observed in different cultures. Therefore, its use for paleoenvironmental investigations, as complementary indicators of human presence, could be really interesting in order to establish with more precision the habitat in which man has developed. La importancia que la Criptogamia debe tener como fuente auxiliar de la Arqueología, queda de manifiesto por el numeroso número de datos que desde la Ecología y la Palinología nos facilitan las criptógamas. La relación entre éstas y el hombre ha sido puesta de manifiesto en distintas culturas, por lo que su utilización en estudios paleoambientales puede jugar un papel sumamente interesante para delimitar con mayor precisión el hábitat en que se desenvolvió el hombre.
Variación espacial y estacional de grupos funcionales de bacterias cultivables del suelo de un bosque tropical seco en México Spatial and seasonal variation of soil culturable-bacterial functional groups in a Mexican tropical dry forest
Noé Manuel Monta?o,Ana Lidia Sandoval-Pérez,Maribel Nava-Mendoza,Juan Manuel Sánchez-Ya?ez
Revista de Biología Tropical , 2013,
Abstract: Los bosques tropicales secos tienen una amplia heterogeneidad ambiental y por lo tanto se podría esperar una variación temporal y espacial en la abundancia y tipo de grupos bacterianos activos. Se evaluó, durante dos a os consecutivos, el efecto de la estacionalidad de la lluvia sobre algunos grupos bacterianos cultivables y nutrimentos del suelo en dos posiciones topográficas (crestas vs laderas) en el bosque tropical seco, Chamela Jalisco, México. La hipótesis fue que la variación temporal y espacial de la disponibilidad de recursos afectaría la abundancia de los grupos bacterianos funcionales (heterótrofas totales, celulolíticas, solubilizadores de fosfatos y nitrificantes) del suelo. En las crestas, el suelo fue más orgánico y con mayor concentración de nutrimentos totales y C orgánico lábil que en la ladera, registrando más bacterias heterótrofas y solubilizadoras de fosfato. En ambas posiciones topográficas la concentración de C y nutrimentos, así como el número de bacterias heterótrofas y solubilizadoras de P, decrecieron de la estación seca a la lluviosa en ambos a os. En contraste, las bacterias nitrificantes fueron mayores en el suelo de la ladera, y al igual que las celulolíticas, tuvieron un patrón estacional opuesto a las bacterias heterótrofas, asociado a la disminución del C lábil y de la calidad de la materia orgánica. En conclusión, se sugiere que el relieve, la estacionalidad y la variación inter-anual de la lluvia regulan interactivamente la relación entre el C disponible y la estructura de las comunidades bacterianas del suelo en el bosque tropical seco de Chamela. Microbial biomass and activity in soils are frequently studied in tropical dry forests, but scarce information is available about the relationships between functional bacterial groups and soil fertility, where relief interacts with rainfall seasonality. The culturable-bacterial groups and nutrients were studied during two consecutive years in soils from two topographic areas of different relief (hilltop vs hillslope) in a tropical dry forest from Chamela Jalisco, Mexico. We expected that seasonal and spatial variation in soil resources availability affects the abundance of functional culturable-bacterial groups. To evaluate this, fifteen soil cores (1kg), 0-5cm depth, were taken in the dry, early rainy and rainy seasons, from each of the ten replicate plots in hilltop and hillslope areas located in three microbasins. We found that hilltop soils were more organic and had higher concentration of labile C and total nutrient forms than hillslope soils, for which these soils had
Volatile Organic Compounds Produced by Human Skin Cells
ACEVEDO,CRISTIAN A; SáNCHEZ,ELIZABETH Y; REYES,JUAN G; YOUNG,MANUEL E;
Biological Research , 2007, DOI: 10.4067/S0716-97602007000400009
Abstract: skin produces volatile organic compounds (vocs) released to the environment with emission patterns characteristic of climatic conditions. it could be thought that these compounds are intermediaries in cell metabolism, since many intermediaries of metabolic pathways have a volatile potential. in this work, using gas chromatography, we answered the question of whether voc profiles of primary cultures of human dermal fibroblasts were affected by the type of culture conditions. vocs were determined for different types of culture, finding significant differences between skin cells grown in classical monolayer culture -2d- compared with 3d matrix immobilized cultures. this indicates that voc profiles could provide information on the physiological state of skin cells or skin
Volatile Organic Compounds Produced by Human Skin Cells
CRISTIAN A ACEVEDO,ELIZABETH Y SáNCHEZ,JUAN G REYES,MANUEL E YOUNG
Biological Research , 2007,
Abstract: Skin produces volatile organic compounds (VOCs) released to the environment with emission patterns characteristic of climatic conditions. It could be thought that these compounds are intermediaries in cell metabolism, since many intermediaries of metabolic pathways have a volatile potential. In this work, using gas chromatography, we answered the question of whether VOC profiles of primary cultures of human dermal fibroblasts were affected by the type of culture conditions. VOCs were determined for different types of culture, finding significant differences between skin cells grown in classical monolayer culture -2D- compared with 3D matrix immobilized cultures. This indicates that VOC profiles could provide information on the physiological state of skin cells or skin
Lernmatrix de Steinbuch: Avances Teóricos
Sánchez Garfias, Flavio A;Díaz de León S, Juan Luis;Yá?ez Márquez, Cornelio;
Computación y Sistemas , 2004,
Abstract: this paper follows the work presented in (sánchez-garfias et al, 2002) and shows the advances of developing a theoretical framework which describes the behavior of the lernmatrix. the lernmatrix is an associative memory created in 1961 by the german scientific karl steinbuch. the obtained results allow to position the lernmatrix as a good alternative for pattern recognition and classification, even after four decades from its creation.
Cuantificación del Error en las Mediciones Debido a la Frecuencia de Muestreo
Sánchez F., Luis Pastor;Díaz de León, Juan Luis;Yá?ez M., Cornelio;Herrera Charles, Roberto;
Computación y Sistemas , 2004,
Abstract: the sampling frequency is essential by their influence in the measurement's accuracy. their effect is decisive when it is necessary to obtain the signal pick values. the methods to improve the quality of the acquired data are related with system operation in real time or if it is admitted to carry out samples taking and later on the data analysis. this paper presents the mathematical expressions of maximum error in measuring the peak values of a continuous and sinusoidal signal according to the sampling frequency. such expressions can be applied in signals where one or several main harmonics are relevant. this paper also shows the relationship between the sampling frequency and the accuracy of statistical calculations, used by peak values, with experimental data of the water level in wave generation laboratories. it is interpolated by using fourier fast transform (fft) and cubic splines. both methods are compared in programming and signal analysis environments, where they are available, like the lab view and the matlab.
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