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Refractory Ceramics Synthesis by Solid-State Reaction Between CaCO3 (Mollusk Shell) And Al2O3 Powders

JOSE GUADALUPE MIRANDA HERNANDEZ MAYAHUEL ORTEGA AVILES Héctor Herrera Hernández CARLOS OMAR GONZALEZ MORAN GEORGINA GARCIA PACHECO ENRIQUE ROCHA RANGEL (2018)

Calcium aluminate-based refractory ceramic was developed as an innovative refractory material, using garden snail (Helix aspersa) shells as a natural source of CaCO3. A 1:1 molar ratio mixture of CaC O3 from snail shells and commercial Al2O3 powder was prepared by means of high-energy mechanical milling. The mixed powder was compacted in cylindrical samples (disks) and consolidated by sintering at 1450°C and 1500°C for 1h. The density and porosity were evaluated using the Archimedes principle, while the mechanical properties (hardness, fracture toughness, and shear modulus) were determined by indentation and ultrasonic methods, respectively. The thermal shock resistance was tested by heating samples to temperatures between 900 and 1400°C and subsequent quenching in water at room temperature. X-ray diffraction patterns of sintered samples indicate the formation of different calcium aluminate phases, such as CaAl12O (krotite/monoclinic),CaAl4O7 (grossite/monoclinic) and CaAl2O (hibonite-5H/hexagonal). The fracture toughness and shear modulus values of materials sintered at 1450°C were higher (0.48 MPa•m1/2)) and 59 GPa, respectively than those of materials sintered at 1500°C (0.43 MPa•m1/ 2 and 55 GPa, respectively). Also changes in the bulk density, hardness and thermal shock resistance values were observed in materials sintered at 1450°C and 1500°C.

Article

Refractories Calcite Alumina Snail shells (mollusk shells) Refractory calcium aluminate ceramics Sintering process Mechanical properties Thermal shock resistance BIOLOGÍA Y QUÍMICA

Cerámica Reforzada con Fibras de Alúmina; Material para Aplicación en la Construcción

SILVERIO HERNANDEZ MORENO (2012)

El artículo presenta un estudio, el cual se desarrolló en el laboratorio un nuevo material de tipo compuesto, de matriz cerámica y reforzado con fibras de alúmina, las cuales también son de manufactura cerámica. El trabajo inició con el desarrollo de un método particular de selección y evaluación de materiales, para aplicaciones en la construcción de edificios, siendo este método la base principal del estudio, es decir, del desarrollo del nuevo material. Este nuevo material se decidió llamarlo Reforcer®, y como se ha señalado, es un material cerámico de tipo compuesto, que contiene como punto innovador, que está reforzado con fibras cerámicas de alúmina, lo cual hace que se mejoren muchas propiedades y características de las cerámicas tradicionales, sobre todo aspectos de resistencia mecánica, térmica y acústica; lo que nos permite utilizarlo en aplicaciones especiales y diversas en la construcción de edificios en México.

This article presents a case of study in which a new composite material was developed in the laboratory containing a ceramic base material, and it is reinforced with alumina fibers, which are also derived from ceramic materials. This study began with a development of a method to select and to evaluate building materials, thus the method is important part in the study of the development of this new material. It was decided to call this ceramic material Reforcer®, because it has been reinforced with ceramic alumina fibers, which improves several properties of the traditional ceramics, like mechanic, thermal and acoustical properties, therefore, this material can be used in special and diverse applications in the building construction industry in Mexico.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Evaluación de materiales Materiales de construcción Cerámicos Evaluation of materials Materials of construction Ceramics

Canales de potasio (MAXI-K y K ATP ) en la actividad eléctrica neuronal

JUAN JOSE ACEVEDO FERNANDEZ (2001)

En este trabajo se estudia la participación de los canales de potasio activados por calcio y la de los sensibles ATP en la actividad eléctrica de las neuronas secretoras del acocil Procambarus clarkii (crustáceo decápodo). Se describe y discute la participación de cada canal en el potencial de membrana, así como su contribución relativa en la corriente saliente total. Los registros del potencial de membrana y de la corriente total de la célula fueron obtenidos mediante la técnica de parche perforado con nistatina en dos modos de registro: fijación de corriente y fijación de voltaje, respectivamente.

Book

BIOLOGÍA Y QUÍMICA Channels, Potassium Calcium Calcio Neuronas Procambarus clarkii

Development and Characterization of Edible Films Based on Mucilage of Opuntia ficus-indica (L.)

MIGUEL ESPINO DIAZ JOSE DE JESUS ORNELAS PAZ MIGUEL ANGEL MARTINEZ TELLEZ (2010)

Mucilage of Opuntia ficus-indica (OFI) was extracted and characterized by its composition and molecular weight distribution. Mucilage film-forming dispersions were prepared under different pHs (3, 4, 5.6, 7, and 8) and calcium concentration (0% and 30% of CaCl2, with respect to mucilage’s weight), and their particle size determined. Mucilage films with and without calcium (MFCa and MF, respectively) were prepared. The effect of calcium and pH on mucilage films was evaluated determining thickness, color, water vapor permeability (WVP), tensile strength (TS), and percentage of elongation (%E). The average molecular weight of the different fractions of mucilage was: 3.4 × 106 (0.73%), 1 × 105 (1.46%), 1.1 × 103 (45.79%), and 2.4 × 102 Da (52.03%). Aqueous mucilage dispersions with no calcium presented particles with an average size d(0.5) of 15.4 μm, greater than the dispersions with calcium, 13.2 μm. MFCa films showed more thickness (0.13 mm) than the MF films (0.10 mm). The addition of calcium increased the WVP of the films from 109.94 to 130.45 gmm/m2dkPa. Calcium and pH affected the mechanical properties of the films; the largest TS was observed on MF films, whereas the highest %E was observed on MFCa films. The highest differences among MF and MFCa films were observed at pHs 5.6 and 7 for TS and at pHs 4 and 8 for %E. No effect of pH and calcium was observed on luminosity and hue angle. Chroma values were higher for MF when compared with MFCa, and increased as pH of the films increased.

Conference proceedings

Calcium Mucilage CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA OTRAS ESPECIALIDADES FÍSICAS OTRAS

Regulation of the slow vacuolar channel by luminal potassium: Role of surface charge

MANUEL MARTINEZ ESTEVEZ (2005)

Voltage-dependent activation of slow vacuolar (SV) channels has been studied on isolated patches from red beet (Beta vulgaris L.) vacuoles. Isoosmotic variation of vacuolar K+ from 10 to 400 mM in Ca 2+-free solutions at the vacuolar side shifted the SV channel activation threshold to more positive voltages. The effect of K+ could be mimicked by additions of choline or N-methyl D-glucamine and could be explained by unspecific screening of the negative surface charge. Fitting the dependence of voltage shift on K+ concentration to the Gouy-Chapman model yields a surface charge density of 0.36 ± 0.05 e -/nm2. Negative surface potential also tended to increase the local concentration of permeable ions (K+), resulting in anomalously high single-channel conductance, ∼200 pS in 10 mM KCl. An increase of ionic strength due to addition of impermeable cations greatly reduced the unitary conductance. Large positive shift of the SV channel voltage dependence, caused by physiological (0.5 mM) free vacuolar Ca2+, was partly ameliorated by increasing luminal K+. We interpreted these results as follows: K+ induced a reduction of surface potential, hence i) causing a positive shift of the voltage dependence and ii) a dilution of Ca2+ in the membrane vicinity, thus reducing the inhibitory effect of vacuolar Ca2+ and causing a negative shift of the SV channel voltage dependence, with a sum of the two shifts being negative.

Article

 CALCIUM PATCH CLAMP POTASSIUM SLOW VACUOLAR CHANNEL VACUOLE VOLTAGE GATING BIOLOGÍA Y QUÍMICA

Transferencia nutrimental y crecimiento de pinos neotropicales con hongos comestibles ectomicorrízicos en dos sustratos

MA. CONCEPCION RENTERIA CHAVEZ (2015)

Tesis (Maestría en Ciencias, especialista en Edafología).- Colegio de Postgraduados, 2015.

La ectomicorriza es una simbiosis mutualista de enorme importancia en la producción de árboles de interés forestal. Uno de los criterios de selección de los hongos empleados de gran interés actualmente, es su comestibilidad, por la importancia económica, ecológica y cultural de los hongos comestibles ectomicorrízicos (HCE) como un producto forestal no maderable. Se evaluó el efecto de la inoculación con 3 HCE, ampliamente comercializados en México, en el crecimiento y contenido nutrimental de Pinus greggii, crecido en un sustrato experimental, y un sustrato comercial enriquecido con un fertilizante de liberación lenta. Dos años después de la siembra, se observaron conspicuas diferencias en altura, biomasa aérea y radical y contenido de macro y micronutrimentos entre plantas inoculadas y no inoculadas, independientemente de la especie fúngica y del sustrato. A pesar de que plantas crecidas en sustrato comercial, tuvieron mayor crecimiento y contenido nutrimental, sus porcentajes de colonización fueron conspicuamente menores que plantas crecidas en sustrato experimental. Existieron evidentes diferencias en la transferencia nutrimental a la parte aérea de los pinos inoculados, entre las especies fúngicas. La transferencia de Ca por Laccaria laccata; de Na por L. bicolor y de Mn por Hebeloma leucosarx registradas en el sustrato experimental; constituyen uno de los pocos reportes conocidos de transferencia de dichos nutrimentos en gimnospermas por HCE. Se demuestra que la selección de sustratos, constituye un factor clave en la producción de plantas ectomicorrizadas y que las 3 especies de HCE evaluados tienen un enorme potencial en la producción de P. greggii. Adicionalmente se efectuaron bioensayos iniciales con Pinus patula y P. ayacahuite. _______________ NUTRIENT TRANSFER AND GROWTH OF NEOTROPICAL PINES WITH EDIBLE ECTOMYCORRHIZAL MUSHROOMS IN TWO SUBSTRATES. ABSTRACT: The ectomycorrhiza is a mutualistic symbiosis of paramount importance in the production of trees with importance in forestry. Currently, one the selection criteria of ectomycorrhizal fungi of great importance is their edibility, due to the economic, ecologic and cultural relevance of the edible ectomycorrhizal mushrooms (EEM) as a non-timber forest product. The effect of the inoculation with 3 EEM, widely sold in Mexico, on the growth and nutrient contents of Pinus greggii, grown in an experimental substrate and a commercial substrate enriched with a slow-release fertilizer, was evaluated. Two years after sowing, conspicuous differences in terms of height, shoot and root biomass and macro and micronutrient contents between inoculated and non-inoculated plants, were recorded, independently of the fungal species and the substrate. Despite the fact that plants grown in commercial substrate had higher growth and nutrient contents, their ectomycorrhizal colonization percentages were conspicuously smaller than those of plants grown in experimental substrate. Evident differences in the nutrient transfer to the inoculated plant shoots among the evaluated fungal species were recorded. Ca mobilization by Laccaria bicolor, Na by L. bicolor and Mn by Hebeloma leucosarx recorded in the plants growing in experimental substrate, constitute one of the few known reports of transference of these nutrients in gymnosperms by EEM. It is demonstrated that the selection of substrates, constitutes an important factor in the production of ectomycorrhizal plants and that the 3 evaluated species of EEM have an enormous potential in the production of P. greggii. Additionally, some preliminary bioassays with Pinus patula and Pinus ayacahuite were carried out.

Master thesis

Hongos comestibles ectomicorrízicos Biotecnología forestal Transferencia nutrimental Sodio Calcio Magnesio Edible ectomycorrhizal mushrooms Biotechnological forestry Nutrient transfer Sodium Calcium Magnesium Edafología Maestría SILVICULTURA

Síntesis y caracterización de nanopartículas de fosfato dicálcico y su evaluación en pollos de engorda

DIANA ANGELICA GUTIERREZ ARENAS (2015)

Tesis (Doctorado en Ciencias, especialista en Ganadería).- Colegio de Postgraduados, 2015.

El fosfato dicálcico (FD) es comúnmente utilizado como fuente de fósforo (P) en la alimentación avícola y una posible mejora en la disponibilidad del FD, puede resultar del uso de nanopartículas de FD (NPFD), por lo que en el presente estudio se empleó el método de coprecipitación para la obtención de estas. La síntesis se llevó a cabo mediante el uso de dos precursores: fosfato de sodio (Na2HPO4) y cloruro de calcio (CaCl2) a temperatura ambiente, con agitación constante y pH controlado. Se utilizó como agente disgregante el polímero polivinilpirrolidona (PVP) y se llevó a cabo un lavado de sales por centrifugación. La obtención de sólidos se realizó por liofilización a -46°C y se caracterizaron por Microscopia Electrónica de Barrido y de Transmisión, Dispersión dinámica de Luz, Espectroscopia de energía dispersa, Espectroscopia de infrarrojo con transformadas de Fourier y Difracción de rayos X. Se obtuvieron nanopartículas de forma prismática con un diámetro de 20 a 80 nm compuestas en su mayoría de fosfato de calcio en su fase monetita (FD anhidro) con algunos restos de hidroxiapatita. Las NPFD cumplen con la estequiometria Ca:P de 1:1.1, lo cual confirma la sustancia obtenida con formula CaHPO4. Estos resultados dan a las NPFD buenas características fisicoquímicas para ser utilizadas en la alimentación avícola. _______________ SYTHESIS AND CHARACTERIZATION OF DICALCIUM PHOSPHATE NANOPARTICLES FOR APPLICATION IN POULTRY NUTRITION. ABSTRACT: Dicalcium phosphate (DAP) is commonly used as a source of phosphorous (P) in the poultry feed and a possible improvement in the availability of the FD can result from use of nanoparticles FD (NPFD), so in this study the method used coprecipitation to obtain these. The synthesis was carried out using two precursors: sodium phosphate (Na2HPO4) and calcium chloride (CaCl2) at room temperature with constant stirring and controlled pH. It was used as the disintegrating agent polyvinylpyrrolidone polymer (PVP) and is carried out by centrifugation washed salt. The solid obtained was performed by lyophilization to -46 ° C and they were characterized by transmission and Scanning Electron Microscopy, Dynamic Light Scattering, energy dispersive spectroscopy, infrared spectroscopy characterized with Fourier transform and X-ray diffraction. Prismatic nanoparticles were obtained with a diameter of 20 to 80 nm composed mostly of calcium phosphate in its phase monetite (FD anhydrous) with some traces of hydroxyapatite. NPFD meet the stoichiometric Ca: P of 1: 1.1, which confirms the substance obtained with formulated CaHPO4. These results give the NPFD good characteristics for use in poultry feed.

Doctoral thesis

Nanotecnología Fosfato de calcio Innovación tecnológica Avicultura Nanotechnology Poultry nutrition Calcium phosphate Technological innovation Poultry farming Ganadería Doctorado CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS PRODUCCIÓN ANIMAL AVICULTURA

El karst de Yucatán: su origen, morfología y biología

The karst of Yucatan: its origin, morphology and biology

HECTOR ESTRADA MEDINA JUAN JOSE MARIA JIMENEZ OSORNIO OSCAR OMAR ALVAREZ RIVERA Roberto Carlos Barrientos Medina (2019)

El karst del estado de Yucatán, México,tiene su origen en los arrecifes coralinos y sedimentos marinos que, al exponerse a la superficie, formaron la roca caliza. Los procesos de solubilización-precipitación de esta roca han promovido la ausencia de corrientes de agua superficiales, un relieve ligeramente ondulado con planicies, depresiones y montículos, afloramientos y presencia de cenotes. Los diferentes grados de porosidad y dureza de la roca han permitido la formación desde pequeñas oquedades y acumulaciones de suelo, hasta complejos sistemas de cuevas secas y húmedas. El manejo de este tipo de áreas debe partir del conocimiento de su origen, morfología y biología para garantizar el uso sustentable de los recursos naturales. Se requiere especial atención en el manejo de la extracción de roca caliza, las actividades turísticas y productivas relacionadas con el uso de agua del acuífero, así como el volumen y calidad de las descargas de aguas residuales al suelo, cenotes y el mar

The karstic environment of the state of Yucatán, Méxicohas its origin on the coral reefs and marine sediments that, after being exposed to surface conditions, formed limestone. Solubility and precipitation processes of this rock have promoted the absence of surface water currents, a slightly undulated relief with plains, depressions and mounds, fractured outcrops and presence of sinkholes. The different levels of porosity and hardness of the rock have allowed the formation of small hollows, soil pockets hollows, as well as complex systems of dry and wet caves. The management of this kind of areas must consider its origin, morphology and biology to guarantee the sustainable use of the natural resources. Special attention needs to be paid on the management of the extraction of limestone rocks, the touristic and productive activities related to the use of water from the aquifer, as well as the volume and quality of the water discharges to soil and sinkholes

Article

BIOLOGÍA Y QUÍMICA Paisaje kárstico Roca calcárea Roca caliza Carbonato de calcio Cenotes Karstic landscape Calcareous rock Llimestone Calcium carbonate Sinkholes

Identification of calcium stress induced genes in amaranth leaves through suppression subtractive hybridization

HUGO SERGIO AGUILAR HERNANDEZ MARTHA LETICIA SANTOS MARTINEZ MA. FABIOLA LEON GALVAN ALBERTO BARRERA PACHECO EDUARDO ESPITIA RANGEL ANTONIO DE LEON RODRIGUEZ RAMON GERARDO GUEVARA GONZALEZ ANA PAULINA BARBA DE LA ROSA (2011)

"Calcium (Ca2+) is a critical ion for the growth and development of plants and plays an important role in signal transduction pathways in response to biotic and abiotic stresses. We investigated the Ca2+ stress responsive-genes in amaranth leaves by using the suppression subtractive hybridization technique. Screening of the libraries generated 420 up-regulated transcripts and 199 down-regulated transcripts. The differentially expressed transcripts were associated with general stress response, transcription factors, gene regulation, signal transduction, and some other with unknown function. Selected genes were used to study their differential regulation by sqRT-PCR. Among the up-regulated transcripts, a fragment containing the motif of C3HC4-type RING-Zinc family was further characterized. The ORF of amaranth zinc finger protein (AhZnf) has a closer relationship with its ortholog from Ricinus communis while is distantly related to the Arabidopsis thaliana C3HC4-type ortholog. We have identified a novel putative zinc finger protein along with other novel proteins such as the wall associated kinase, phosphoinositide binding protein, and rhomboid protease involved in response to Ca2+ stress in amaranth leaves."

Article

Amaranthus hypochondriacus Calcium stress Subtractive cDNA libraries Zinc finger protein BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA)

Síntesis y caracterización de un recubrimiento de tipo PMMA-CaO

ANA MARIA ARIZMENDI MORQUECHO (2010)

En este trabajo se reporta el desarrollo de un material compuesto de polimetacrilato de metilo (PMMA) con óxido de

calcio, mediante una síntesis sencilla para su aplicación como posible recubrimiento biocompatible en insertos de

polietileno de ultra alto peso molecular (UHMWPE) de prótesis de rodilla. La obtención del óxido de calcio se llevó a

cabo por descomposición térmica de la cáscara de huevo, mientras que la síntesis del PMMA se realizó por medio de la

polimerización del monómero metacrilato de metilo (MMA). La preparación del recubrimiento se llevó a cabo por

inmersión del sustrato de UHMWPE en PMMA y posteriormente en una solución de CaO, obteniendo un recubrimiento

denso con 97 μm de espesor y buena adherencia.

Conference proceedings

PMMA Calcium oxide BIOLOGÍA Y QUÍMICA QUÍMICA OTRAS ESPECIALIDADES QUÍMICAS OTRAS