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Molecular modeling and expression analysis of a MADS-box cDNA from mango (Mangifera indica L.)
Get PDF"MADS-box genes are a large family of transcription factors initially discovered for their role during development of flowers and fruits. The MADS-box transcription factors from animals have been studied by X-ray protein crystallography but those from plants remain to be studied. In this work, a MADS-box cDNA from mango encoding a protein of 254 residues was obtained and compared. Based on phylogenetic analysis, it is proposed that the MADS-box transcription factor expressed in mango fruit (MiMADS1) belongs to the SEP clade of MADS-box proteins. MiMADS1 mRNA steady-state levels did not changed during mango fruit development and were up-regulated, when mango fruits reached physiological maturity as assessed by qRT-PCR. Thus, MiMADS1 could have a role during development and ripening of this fruit. The theoretical structural model of MiMADS1 showed the DNA-binding domain folding bound to a double-stranded DNA. Therefore, MiMADS1 is an interesting model for understanding DNA-binding for transcriptional regulation.
Carbonaceous and protein constituents in dairy wastewater lead to a differentiated current generation in microbial fuel cells (MFCs)
Get PDF"The effect of real dairy wastewater (DWW) additions on the current density generated by a bioanode was evaluated in a half cell configuration under potentiostatic control, thus simulating the anodic chamber of a Microbial Fuel Cell. Low substrate additions increased current density up to 1655 ± 136 mA m−2, forming a two-current peak pattern. Then the system was tested with a casein-lactose synthetic media. A high protein concentration reduced the current density; individual compounds led to the highest current (330.5 mA m−2 with casein; 1276 mA m−2 with lactose). Moreover, the protein reduced the current start up time.""Se evaluó la densidad de corriente de un bioánodo con adiciones de agua residual lacto-alimenticia. A menor volumen de substrato adicionado, se observó mayor producción de densidad de corriente (1655 ± 136 mA m−2), con un patrón de dos picos de corriente. El sistema evaluado con un medio sintético de caseína-lactosa mostró que una alta concentración de proteína afectó negativamente la corriente producida; los componentes individuales generaron los valores más altos de corriente (330.5 mA m−2 con caseína; 1276 mA m−2 con lactosa). Adicionalmente la proteína favoreció el inicio de generación de corriente.
Enriquecimiento de comunidades sulfato reductoras degradadoras de acetato en condiciones ácidas.
Get PDFTesis (Maestría en Ciencias Ambientales)"El drenaje ácido de mina (DAM) es un flujo de agua proveniente de jales mineros, que se caracteriza por presentar pH ácido y altas concentraciones de sulfatos y metales. Debido a sus características fisicoquímicas, el DAM es una amenaza para el ambiente y requiere ser tratado de una manera adecuada. Para su tratamiento, se pueden emplear reactores sulfato reductores. En estos procesos, las bacterias sulfato reductoras (BSR) aprovechan el sulfato y lo reducen a sulfuro, el cual es empleado para precipitar los metales presentes en el medio. El desarrollo de esta tecnología tiene dos limitantes: baja eficiencia en pH ácido y la acumulación de acetato. Ambas limitantes se deben a características propias de las BSR, por lo que se ha propuesto emplear comunidades sulfato reductoras en lugar de cepas puras. El objetivo de este trabajo fue establecer si es posible enriquecer comunidades sulfato reductoras que sean capaces de degradar acetato y desarrollarse en condiciones ácidas, empleando muestras ambientales como inóculo. Además, se intentó determinar la estructura de dichas comunidades mediante técnicas de biología molecular. Con este fin, se realizaron enriquecimientos empleando como inóculo un sedimento con un historial de exposición a DAM. En los enriquecimientos se examinaron los efectos de tres donadores de electrones: acetato, lactato y glicerol, los cuales fueron empleados en tres diferentes niveles de acidez, pH: 3, 4 y 5. Por último, se evaluaron dos técnicas de cultivo para enriquecimientos a pH = 3: aclimatación y presión selectiva. Para determinar el desempeño de la comunidad, se llevó a cabo un seguimiento de la producción de sulfuro y del consumo de acetato a lo largo del tiempo. Para determinar la estructura de las comunidades presentes en los enriquecimientos se empleó la técnica de PCR/T-RFLP. El desempeño de los enriquecimientos resultó estar estrechamente relacionado con el pH inicial, el donador de electrones y la técnica de cultivo. En los experimentos de presión selectiva, el glicerol resultó ser un sustrato adecuado para la sulfato reducción a los tres niveles de acidez, aunque favoreció la acumulación de acetato. En cambio, se observó inhibición del crecimiento cuando se empleó acetato (tratamientos con pH >5) y lactato (tratamientos con pH >4) como donadores de electrones.""The acid mine drainage (AMD) is the outflow of acidic water from mine tailings. It canreach extremely low pH values and usually contains elevated concentrations of heavy metals and sulfate. Therefore, acid mine drainages can be very recalcitrant and toxic, and should be treated appropriately. Recently, several efforts have been made to develop sulfate reduction-based processes in order to treat AMD. Sulfate reduction processes rely on the metabolic activities of sulfate-reducing bacteria (SRB), which are responsible for the sulfide production. The sulfide produced is used to precipitate the metals present in the AMD. The main limitations observed in sulfate-reducing processes are the acetate accumulation and the inhibition of SRB at low pH. Both limitations are related to the metabolism of SRB. Therefore, it has been proposed the use of sulfate reducing communities from naturally acidic environments to overcome these limitations. The objective of this work was to obtain acetate consuming-sulfate reducing communities at low pH, using environmental samples as inoculum. In order to achieve this goal, microbial cultures were enriched from sediments of a water curse generated from the tailings of an abandoned sulfur mine. The composition of the media was based on the minimum sulfate reduction medium. Enrichments were performed employing three electron donors (acetate, lactate or glycerol), and two cultivation strategies (acclimation or selection) during 90 days. Selective pressure enrichments were performed at three acidity levels (pH = 3, 4 and 5). Acclimated enrichments were developed as follows: samples were first incubated at pH 5 during 50 days and then at pH 4 for another 50 days. Finally samples were incubated at pH 3 for 90 days. At every change of pH, the medium was removed by decantation and fresh medium at the desired pH was added to the bottles. All microcosms were made by quintuplicates and sampled every 10 days to measure pH, sulfide production and acetate consumption in order to evaluate the performances of the enrichments. T-RFLP analyses were conducted to stablish the microbial communities’ structure present in the enrichments. The results showed that the performance of the microbial communities was closely related to the initial pH, electron donor, and cultivation technique employed during the enrichment process.
Síntesis de nanopartículas metálicas y su aplicación en la reducción de 4-nitrofenol por un consorcio microbiano anaerobio
Get PDF"Las nanopartículas metálicas de paladio pueden actuar como catalizadores y modificando los catalizadores con la adición de un segundo metal como el cobre aumentan el rendimiento de las reacciones. Para el tratamiento de aguas residuales se utilizan tratamientos biológicos anaerobios con los cuales se pretende remover contaminantes de los efluentes industriales. Este estudio se enfocó en la implementación de una técnica innovadora, dentro de la cual se adicionaron nanopartículas metálicas de paladio y paladio-cobre, sintetizadas químicamente, como catalizadores con la finalidad de acelerar las reacciones de degradación del p-nitrofenol dentro de un sistema biológico. Se evaluó el efecto de diferentes nanopartículas de Pd, y bimetálicas sintetizadas por dos métodos distintos (PdCu (1) y PdCu (2)), todos aplicados a una concentración de 20 ppm en los sistemas biológicos para determinar su actividad catalítica. Los sistemas se inocularon con un lodo granular anaerobio [2 g SSV/L] donde la fuente de carbono empleada fue una mezcla de etanol-lactato [1 g de DQO/L]. Todos los experimentos se realizaron en lote con un volumen de trabajo de 50 mL, temperatura de 30 °C y pH aproximado de 7.5 durante 50 horas. Los resultados obtenidos señalan que las nanopartículas de PdCu (2) presentan una actividad catalítica mayor, dando como resultado un valor de la constante de degradación (k) más alto en comparación con los demás tratamientos (k=0.1596 h-1). En todos los experimentos se obtuvo una completa reducción del p-nitrofenol, en contraste con lo obtenido para p-aminofenol, el cual fue recuperado en su totalidad únicamente en los sistemas con nanopartículas de PdCu, lo cual demuestra que la adición de cobre en el catalizador aumenta la selectividad hacia el producto deseado. Las nanopartículas obtenidas de Pd presentaron un tamaño promedio de ~10 nm; las de PdCu (1) un tamaño de ~3 nm y las de PdCu (2) tamaños alrededor de 2 - 12 nm, estos tamaños son idóneos para ser utilizados como catalizadores, debido a la gran área superficial por unidad de volumen que presentan, superficie en la cual se lleva a cabo la reacción. El presente trabajo sienta las bases para el desarrollo de un sistema de tratamiento basado en la actividad biológica de un consorcio anaerobio y en la actividad catalítica de nanopartículas metálicas para ser aplicado en la biodegradación de contaminantes presentes en aguas residuales industriales.""For the treatment of wastewater anaerobic biological systems are used with the purpose to remove pollutants from wastewater. Palladium metal nanoparticles can act as catalysts and modifying catalysts with the addition of a second metal such as copper increase the yield of the reactions. This study focuses on the application of an innovative technique, in which chemically synthesized nanoparticles of palladium and palladium-copper were added into biological systems in order to accelerate the rate of degradation of p-nitrophenol. The effect of different nanoparticles of Pd, PdCu (1) and PdCu (2) [20 ppm] were studied aiming its catalytic activity within biological systems. The systems were inoculated with granular anaerobic sludge [2 g VSS/L] using a mixture of ethanol-lactate [1 g COD/L] as the carbon source. All the experiments were conducted in batch (50 mL), temperature of 30°C, and pH of 7.5 for approximately 50 hours. The results showed that PdCu (2) nanoparticles have a greater catalytic activity, resulting in a value of the degradation constant (k) higher as compared to the other treatments (k = 0.1596 h-1). In all the experiments a complete removal of p-nitrophenol was achieved, in contrast with the results for p-aminophenol (reduction product), which was fully recovered only in systems containing PdCu nanoparticles, demonstrating that the addition of copper in the catalyst increases the selectivity to the desired product. Pd nanoparticles obtained showed an average size of 10 nm; PdCu (1) nanoparticles a size of ~ 3 nm and the PdCu (2) nanoparticles a size between 2 - 12 nm, these sizes are suitable for use of these nanoparticles as catalysts, due to the large surface area per unit volume that exhibit, surface in which the reaction takes place. The proposed technology, based on the biological activity of anaerobic consortia and the catalytic input of metallic nanoparticles, could be a promising strategy to selectively remove pollutants from industrial wastewaters.
Optimizing the curie temperature of pseudo-binary RxR'2-xFe17 (R,R' = rare earth) for magnetic refrigeration
Get PDF"Several pseudo-binary RxR2-x'Fe-17 alloys (with R = Y, Ce, Pr, Gd and Dy) were synthesized with rhombohedral Th2Zn17-type crystal structure determined from x-ray and neutron powder diffraction. The choice of compositions was done with the aim of tuning the Curie temperature (T-C) in the 270 +/- 20 K temperature range, in order to obtain the maximum magneto-caloric effect around room temperature. The investigated compounds exhibit broad isothermal magnetic entropy changes, Delta S-M(T), with moderate values of the refrigerant capacity, even though the values of Delta S-M(Peak) are relatively low compared with those of the R2Fe17 compounds with R = Pr or Nd. The reduction on the Delta S-M(Peak) is explained in terms of the diminution in the saturation magnetization value. Furthermore, the Delta S-M(T) curves exhibit a similar caret-like behavior, suggesting that the magneto-caloric effect is mainly governed by the Fe-sublattice. A single master curve for Delta S-M/Delta S-M(Peak)(T) under different values of the magnetic field change are obtained for each compound by rescaling of the temperature axis.
Effects of surface-engineered nanoparticle-based dispersants for marine oil spills on the model organism Artemia franciscana
Get PDF"Fine particles are under active consideration as alternatives to chemical dispersants for large-scale petroleum spills. Fine carbon particles with engineered surface chemistry have been shown to stabilize oil-in-water emulsions, but the environmental impacts of large-scale particle introduction to the marine environment are unknown. Here we study the impact of surface-engineered carbon-black materials on brine shrimp (Artemia franciscana) as a model marine microcrustacean. Mortality was characterized at 50–1000 mg/L, and levels of heat shock protein 70 (hsp70) were characterized at sublethal particle concentrations (25–50 mg/L). Functionalized carbon black (CB) nanoparticles were found to be nontoxic at all concentrations, while hydrophobic (annealed) and as-produced CB induced adverse effects at high concentrations. CB was also shown to adsorb benzene, a model hydrocarbon representing the more soluble and toxic low-molecular weight aromatic fraction of petroleum, but the extent of adsorption was insufficient to mitigate benzene toxicity to Artemia in coexposure experiments. At lower benzene concentrations (25–75 mg/L), coexposure with annealed and as-produced CB increased hsp70 protein levels. This study suggests that surface functionalization for increased hydrophilicity can not only improve the performance of CB-based dispersants but also reduce their adverse environmental impacts on marine organisms.
Consenso en arreglos maestro-seguidores de agentes inerciales
Get PDF"En este trabajo, investigamos el problema de consenso en arreglos maestro-seguidores de sistemas de múltiples agentes con dinámica de segundo orden e inercias significantemente diferentes (agentes inerciales), en redes dirigidas con pesos fijas. Discutimos, como motivación, cómo es posible describir la dinámica de movimiento de un actuador montado en un robot móvil con tracción diferencial, de forma similar a la de un agente inercial. Analizamos los problemas de consenso entre agentes y consenso en arreglos maestro-seguidores, en este último, asumimos que solo una porción (inclusive solo uno) de los agentes seguidores tiene acceso a los estados del maestro. Se dan condiciones necesarias y suficientes bajo las cuales ambos problemas son resueltos, en primer lugar, bajo la suposición de agentes idénticos (i.e. masas iguales) y en segundo, suponiendo que tienen masas diferentes. Los protocolos de consenso, son extendidos para garantizar la convergencia de estados de los agentes a un valor de desviación deseado. En todos los casos de estudio, se presentan simulaciones numéricas para ilustrar los resultados.""In this work, we investigate the consensus problem in master-slaves arrays on systems of multiple agents with second order dynamics and significant inertial differences (inertial agents), in fixed and weighted directed networks. We discus, as a motivation, how is possible to describe the movement dynamics of an actuator coupled on a differential mobile robot, the same way as an inertial agent. We analyze the consensus problem between agents and the consensus problem in master-slave arrays, in this last one, we assume that only a part (including only one) of the followers agents have access to the master’s states. Necessary and sufficient conditions are given to ensure that both problems are solved, in first place, under the supposition of identical agents (i.e. same mass), and in second place, assuming different masses. The consensus protocols are also extended to achieve relative state deviations to a desired value. In all this cases, numerical simulations are given as an illustration of the results.
Geofísica para la localización de agua subterránea en ambientes volcánicos áridos de la Mesa Central. Caso La Dulcita, Villa de Ramos, San Luis Potosí, México
Get PDF"Uno de los problemas más importantes en zonas áridas es el relacionado con la exploración y aprovechamiento de agua subterránea. En este trabajo se presenta el método magnético aéreo y terrestre como herramienta para la localización de zonas asociadas con permeabilidad (fracturamiento) mediante la interpretación de lineamientos y dominios magnéticos aéreos y terrestres. A partir de estas interpretaciones, se emplean métodos eléctricos por medio de secciones y sondeos eléctricos verticales para verificar si las zonas se correlacionan con humedad en el subsuelo. En los casos en que se cumplen ambas condiciones de permeabilidad y humedad, se consideran zonas con altas probabilidades para la localización de agua subterránea en las zonas áridas de la Mesa Central Mexicana. Se presenta la aplicación de estos métodos en una zona rural del Estado de San Luis Potosí, en donde existen problemas con la localización de estos recursos.""One of the most important problems in arid zones is the one related to the exploration and exploitation of groundwater. This paper presents the air and ground magnetic method as a tool for locating zones associated with permeability (fracturing), by means of the interpretation of alignments and of air and ground domains. Based on these interpretations, electrical methods by sections and vertical electrical soundings are used to verify if the zones are correlated to the moisture underground. If both permeability and moisture are met, they are considered as zones with high probability of locating groundwater in the Mexican Central Mesa arid zones. The application of this methodology is presented in a rural population in the State of San Luis Potosí, where problems with the location of these resources exist.
Modeling of groundwater flow and water use for San Luis Potosí Valley aquifer system
Get PDF"Land use changes are currently one of the indisputable factors in the alteration of processes and cycles of the aquifer system in the San Luis Potosí Valley. Due to its importance, is considered indispensable to investigate this detrimental factor of aquifers. The aim of this research is to use a numerical flow model to analyze the impact that land use changes have had on the aquifer. A finite differences numerical model was adapted to the size and hydrological properties of the aquifer system. It consisted of a regular grid with 30 columns and 34 rows with constant spacing of 1000 meters. It has two layers; the first includes the shallow aquifer and the second, the deep aquifer. The initial hydraulic head of the model corresponds to 1986 and was verified for 1995 and 2007. The model shows the development of a drawdown cone (central valley) extending toward the industrial area (southern valley). Piezometric water levels revealed a decrease of 0.6 to 1.6 meters annually during a period from 1977 to 2007. This work demonstrates that it is the consequence of land use changes and of the incessant overall decline in groundwater reserves. Based on the flow model, population growth projections and water use change, the calculated predictions indicate that by 2021, the total established volume of 136 Mm3/year for consume will be reached. The flow model of the San Luis Potosí Valley aquifer system shows a clear effect of the risks associated with aquifer mining.
Compensación del efecto de vaciado gástrico en el control de glucemia para diabéticos tipo 1.
Get PDFTesis (Maestría en Control y Sistemas Dinámicos)"La diabetes es un padecimiento multifactorial crónico que se ha convertido en un problema de salud pública a nivel mundial. Esto ha motivado muchos trabajos científicos; que abordan este problema desde distintos enfoques. En lo que se refiere a la Diabetes Mellitus Tipo 1 (DMT1), existen dos líneas de investigación importantes. La primera consiste en mejorar la calidad de la terapia por medio de inyecciones múltiples diarias de insulina. La segunda línea de investigación está dedicada al diseño del páncreas artificial. En este sentido, resultados recientes obtenidos mediante la teoría de control H1, logran el seguimiento de curvas de tolerancia de sujetos no diabéticos. Siendo que la principal perturbación a los niveles de glucosa en sangre es la ingesta, en esta investigación se estudiarán los efectos del vaciado gástrico y sus efectos dinámicos inducidos sobre la metabolización de carbohidratos en individuos con DMT1 controlados. Ya que se ha demostrado que personas diabéticas suelen presentar vaciado gástrico retardado, partiremos de los modelos que describen el fenómeno del vaciado gástrico, tanto lineales como no lineales reportados en la literatura. Analizaremos las características del vaciado gástrico de tal manera que podamos estudiar el efecto de variaciones paramétricas asociadas a la fuente de carbohidratos y al flujo gástrico. Para tal estudio se acopla el vaciado gástrico en el modelo del metabolismo glucosa-insulina de sujetos con DMT1. Una vez acoplado, el modelo de vaciado gástrico al modelo glucosa-insulina, se probar´a el desempeño de los controladores robustos propuestos en la literatura mediante la Teoría H1 ante distintos escenarios de vaciado gástrico. Los resultados mostrados en este trabajo se soportan solo con simulaciones numéricas.""Diabetes is a multifactorial chronic disease that has become in a worldwide health problem. This has motivated a great number of scientific studies; approaching this problem from different points of view. Regarding of type 1 Diabetes mellitus, there are two important lines of investigation. The first one consists in improving the quality of the therapy by multiple daily injections. The second line of investigation is focused on designing an artificial pancreas. In this way, recent outcomes obtained by H1 control theory, show the non-diabetic subject tolerance curves tracking. Being the main disturbance of glucose levels the oral intake, in this investigation the effects of gastric empty and its dynamic effects induced on carbohydrate metabolism in controlled T1DM subjects will be studied. Due the delay in gastric emptying in diabetic people has been experimentally proven, we’ll start off models describing the gastric empty, linear and nonlinear reported in the literature. We´ll analyze the gastric empty features in such way we could include parametric variations associated to the carbohydrates source and gastric flow in them. For such study, the gastric empty will be included in the glucoseinsulin metabolism model of subjects with T1DM. Once the gastric empty model is included in the glucose-insulin model, the performance of robust controllers proposed using H1 will be studied under different gastric emptying scenarios. Results shown in this work are supported only by numeric simulations.