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Desarrollo de la metodología MEPAM para la determinación de la conexión hidráulica entre una zona de recarga y una de descarga, caso Joya de Luna y Guaxcamá, San Luis Potosí.
Get PDF"En la región Centro-Oriente de México existen zonas con extensos afloramientos de rocas calcáreas plegadas formando sistemas montañosos con intenso desarrollo cárstico. El abastecimiento de agua en esta región se logra en una parte importante a partir de acuíferos controlados por dichos sistemas, por lo que es importante en-tender el comportamiento y dirección de las corrientes de agua subterránea en los sistemas acuíferos de la región. En este trabajo se analiza el flujo subterráneo entre la localidad de Joya de Luna (municipio de Cerritos, San Luis Potosí) y Guaxcamá (municipio de Villa Juárez, S.L.P.) para analizar la posible conexión entre ambas zonas (recarga y descarga) por medio del uso de diversas metodologías, conocidas y nuevas.
Se propone la implementación de un método novedoso, eficaz y factible denomi-nado MEPAM (Metodología Polínica Ambiental) para el estudio de conectividad de acuíferos en medios cársticos, en especial en la identificación de la conectividad entre la zona de recarga y de descarga, utilizando granos de polen como trazadores.
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De manera complementaria, para contrastar y examinar la validación de este mé-todo se emplearon isotopos estables de Deuterio y Oxigeno-18; se empleó además el exceso de deuterio como un factor para el análisis hidrogeológico. Se documentó mediante un levantamiento de la vegetación presente en ambas zonas de estudio, en un radio de 5 km, el tipo de familias existentes en la zona de recarga Joya de Luna y la de descarga en Guaxcamá, y se generó una base de datos con 41 espe-cies polínicas, para la caracterización morfológica. Posteriormente, se hizo una re-colecta de 135 muestras de agua subterránea donde se encontraban suspendidos los granos de polen en los 15 diferentes aprovechamientos de norias y manantiales. El análisis de especies mostró que granos de polen de las especies de Zea mays (Zeama), Avena sativa (Avesa), Cicer arietinum (Cicar) y Quercus sp., característi-cos solo de la zona de recarga se presentaban en la zona de descarga. Los resul-tados polínicos fueron congruentes con la técnica isotópica y el exceso de deuterio en donde se identificaron dos rutas con conexión hidráulica G1 y G2. La ruta G1 conecta a la muestra 11 de la zona de recarga y las muestras 1, 4 y 6 de la zona de descarga. La ruta G2 muestra la conexión hidráulica entre la muestra 15 de la zona de recarga y las muestras 5, 7 y 10 de la zona de descarga. En ambas zonas se presentaron granos de Zeama, Avesa y Cicar. El polen de la familia Quercus sp., propio también de la zona montañosa alta, se detectó en las muestras de los puntos 11, 12 y 15 de la zona de recarga y en los puntos 1, 4, 5, 6, 7, 9 y 10 de la zona de descarga.
Adicionalmente, se documenta en este trabajo otro caso de flujo de agua subterrá-nea con condiciones distintas, en las subcuencas de Santa Catarina y Ocampo-
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Paraíso, en la zona media de San Luis Potosí, 40 km al sur de Joya de Luna, donde la caracterización hidrogeoquímica ha permitido identificar los tipos de aguas sub-terráneas y diversos procesos de interacción agua-roca. La composición del agua subterránea en cada una de estas cuencas refleja la disolución por el agua de lluvia de los minerales de carbonato y magnesio de las rocas carbonatadas de la Forma-ción El Abra (Cretácico medio) y el flujo subterráneo a través de un medio granular con fuerte influencia de material volcánico. Las aguas de tipo Ca-HCO3 y Ca-Mg-HCO3 se modifican durante el flujo subterráneo mediante la incorporación de iones de Na+ y SO-4.
Ambas metodologías han permitido identificar las direcciones de flujo subterráneo, la interacción agua-roca, además MEPAM permitió determinar la conectividad hi-dráulica entre Joya de Luna y Guaxcamá.""In the Central-Eastern region of Mexico there are areas with extensive outcrops of folded calcareous rocks forming mountainous systems with intense karstic develop-ment. The water supply in this region is accomplished in an important part from aq-uifers controlled by these systems, so it is important to understand the behavior and direction of groundwater flows in the aquifer systems of the region. In this work, the underground flow between the town of Joya de Luna (municipality of Cerritos, San Luis Potosi) and Guaxcama (municipality of Villa Juarez, SLP) is analyzed to analyze the possible connection between both zones (recharge and discharge) of the use with different, known and new methodologies. It is proposed the implementation of a novel, effective and feasible method called MEPAM (Environmental Poll Methodology) for the study of connectivity of aquifers in karst environments, especially in the identification of connectivity between the re-charge and discharge zones, using grains of pollen as tracers. In a complementary way, stable isotopes of Deuterium and Oxygen-18 were used to contrast and exam-ine the validation of this method; In addition, excess deuterium was used as a factor for the hydrogeological analysis. It was documented by means of a survey of the vegetation present in both study zones, within a radius of 5 km, the type of families existing in the recharge zone Joya de Luna and the discharge in Guaxcama, and a database with 41 pollen species, for morphological characterization. Subsequently, a collection of 135 groundwater samples of was made where the pollen grains were suspended in the 15 different uses of norias and springs. Species analysis showed that pollen grains of Zea mays (Zeama), Avena sativa (Avesa), Cicer arietinum (Cicar) and Quercus sp., are characteristic species only of the recharge zone, were present in the discharge zone. The pollen results were consistent with the isotopic technique and the deuterium excess in which two routes with hydraulic connection G1 and G2 were identified. Route G1 connects to sample 11 of the recharge zone and samples 1, 4 and 6 of the discharge area. Route G2 shows the hydraulic connection between sample 15 of the recharge zone and samples 5, 7 and 10 of the discharge area. Grains of Zeama, Avesa, and Cicar were presented in both zones. The pollen of the family Quercus sp., also typical of the high mountainous area, was detected in the samples points11, 12 and 15 of the recharge zone and in points 1, 4, 5, 6, 7, 9 and 10 from the discharge area. Additionally, another case of groundwater flow with different conditions is docu-mented in this work, in the sub-basins of Santa Catarina and Ocampo-Paraíso, in the middle zone of San Luis Potosí, 40 km to the south of Joya de Luna, where the hydrogeochemistry characterization has allowed to identify the types of groundwater and various water-rock interaction processes. The composition of the groundwater in each of these basins reflects the dissolution by rainwater of the carbonate and XVII magnesium minerals of the carbonate rocks of the Formation El Abra (Middle Creta-ceous) and the underground flow through a granular medium with strong influence of volcanic material. The waters of type Ca-HCO3 and Ca-Mg-HCO3 are modified during the underground flow by the incorporation of Na + and SO-4 ions. Both methodologies have allowed to identify the directions of underground flow, the water-rock interaction, in addition MEPAM to determine the hydraulic connectivity between Joya de Luna and Guaxcama.
Generation of Sporothrix schenckii mutants expressing the green fluorescent protein suitable for the study of host-fungus interactions
Get PDF"Sporotrichosis is an infection caused by members of the Sporothrix genus, and among them, Sporothrix schenckii is one of the etiological agents. Both, the disease and the causative agent have gained interest in the recent years, because of the report of epidemic outbreaks, and the description of the disease transmission from animals to human beings. Despite the relevance of S. schenckii in the clinical field, there are basic aspects of its biology poorly explored. So far, Agrobacterium tumefaciens-mediated transformation has been reported as an alternative for genetic manipulation of this fungal pathogen. Here, we report the optimization of the transformation method and used this to generate insertional mutants that express the green fluorescent protein in S. schenckii. We obtained five mutant strains that showed mitotic stability and expression of the reporter gene. The strains displayed normal cell wall composition, and a similar ability to interact ex vivo with human monocytes and monocyte-derived macrophages. Moreover, the virulence in larvae of Galleria mellonella was similar to that obtained with the wild-type control strains. These data indicate that these fluorescent mutants with normal ability to interact with the host could be used in bioimaging to track the host-Sporothrix interaction in vivo.
Acorn weight as determinant of germination in red and white oaks: evidences from a common-garden greenhouse experiment
Get PDF"Key message
In Mexican oaks, germination increases with acorn fresh weight across oak species. Within species, these relationships are stronger in red oaks than in white oaks. In both oak groups, fresh weight of acorns increases with their dry biomass.
Context
Mexican oaks are phylogenetically grouped in red and white oaks. White oaks produce heavier acorns than red ones, but no studies have assessed whether this leads to different germination patterns.
Aims
This study was aimed to determine the influence of the fresh weight of acorns on their germination.
Methods
Acorns of red and white oaks were hydrated, weighed, and sowed under greenhouse conditions to assess whether their fresh weight was related with germination. We also assessed whether fresh weight of acorns was related with their dry biomass and/or water accumulation capability.
Results
Hydrated acorns of white oaks were heavier and germinated faster than those of red oaks. Germination percentages increased with acorn fresh weight across oak species. Within species, germination probability increased with acorn fresh weight, but these relationships were more marked in red oaks. Germination speed decreased with acorn fresh weight in red oaks, but these relationships were not found in white oaks. Fresh weight was positively related with acorn dry biomass in all oak species, but it was not related with water content.
Conclusion
Increasing acorn fresh weight enhances germination across oak species. Within species, however, this trait seems to have more influence in red than in white oaks.
Bistable behavior via switching dissipative systems with unstable dynamics and its electronic design
Get PDF"In this work we present a design of a bistable system and its electronic circuit which is generated by a switching system. The switching system is comprised by dissipative subsystems with unstable dynamics based on the jerk equation. For this system with unstable dynamics, it is necessary to use a switching control law in order to change the equilibrium point of the linear part and get bounded trajectories. Also the dynamics of the piecewise linear (PWL) system is illustrated by numerical simulations to depict the bistable states. We present an easy electronic design of the proposed system by employing resistors, capacitors and comparators, to exhibit the capability to generate bistable behavior.
Enhancing saccharification of Agave tequilana bagasse by oxidative delignification and enzymatic synergism for the production of hydrogen and methane
Get PDF"Agave tequilana bagasse is a suitable lignocellulosic residue for energy production. However, the presence of lignin and the heterogeneous structure of hemicellulose may hinder the availability of polysaccharides. In this work, the pretreatment of A. tequilana bagasse with alkaline hydrogen peroxide (AHP) followed by enzymatic saccharification with hemicellulases and cellulases was assessed for the removal of lignin and extraction of fermentable sugars, respectively. Results of the AHP pretreatment indicated that it is possible to attain up to 97% delignification and recover 88% of cellulose and hemicellulose after only 1.5 h of treatment. Regarding the saccharification process, the total sugar yield and productivity were both increased by 2-fold using an enzymatic mixture (cellulases + hemicellulases) compared to single enzyme hydrolysis (cellulases), evidencing synergism. Further evaluation of the hydrolyzates as substrate for hydrogen and methane production, resulted in yields 1.5 and 3.6-times (215.14 ± 13 L H2 and 393.4 ± 13 L CH4 per kg bagasse, respectively) superior to those obtained with hydrolyzates of non-pretreated bagasse processed with a single enzyme. Overall, using AHP pretreatment and subsequent hydrolysis with enzymatic mixtures improves the saccharification of A. tequilana bagasse enhancing the production of hydrogen and methane.
Magnetostructural transitions and magnetocaloric effects in Ni50Mn35In14.25B0.75 ribbons
Get PDF"The structural, thermal, and magnetic behaviors, as well as the martensitic phase transformation and related magnetocaloric response of Ni50Mn35In14.25B0.75 annealed ribbons have been investigated using room-temperature X-ray diffraction (XRD), differential scanning calorimetry (DSC), and magnetization measurements. Ni50Mn35In14.25B0.75 annealed ribbons show a sharper change in magnetization at the martensitic transition, resulting in larger magnetic entropy changes in comparison to bulk Ni50Mn35In14.25B0.75. A drastic shift in the martensitic transformation temperature (TM) of 70 K to higher temperature was observed for the annealed ribbons relative to that of the bulk (TM = 240 K). The results obtained for magnetic, thermal, structural, and magnetocaloric properties of annealed ribbons have been compared to those of the corresponding bulk alloys.
Down-regulation of arginine decarboxylase gene-expression results in reactive oxygen species accumulation in Arabidopsis
Get PDF"Arabidopsis amiR:ADC-L2 is a non-lethal line with several developmental defects, it is characterized by a drastic reduction in free polyamine content. Herein, we found that catalase application had growth-promoting effects in amiR:ADC-L2 and parental Ws seedlings. Differences in ROS content between amiR:ADC-L2 and Ws seedlings were detected. Increased H2O2 levels were found in the amiR:ADC-L2, as well as low AtCAT2 gene expression and reduced catalase activity. Estimation of polyamine oxidase activity in amiR:ADC-L2 line indicated that the over-accumulation of H2O2 is independent of polyamine catabolism. However, increments in NADPH oxidase activity and O2•? content could be associated to the higher H2O2 levels in the amiR:ADC-L2 line. Our data suggest that low polyamine levels in Arabidopsis seedlings are responsible for the accumulation of ROS, by altering the activities of enzymes involved in ROS production and detoxification.
Estudio teórico experimental de compósitos de Y2O3 -GO
Get PDF"El Y2O3 es el compuesto mas abundante de este elemento, el cual ha sido estudia- do por sus propiedades cerámicas y electro-ópticas, sin embargo, recientemente se ́ ha comenzado a reportar el uso de este oxido metálico en conjunto con materiales a ́ base de carbono como el oxido de grafeno para la modificación de electrodos, esto ́ con el fin de evaluar la respuesta en el sensado electroquímico de fármacos. En este trabajo se aborda el estudio del material desde dos perspectivas. La primera para obtener y caracterizar un compósito óxido de grafeno-Y2O3 que tenga buena estabilidad y características experimentales para su aplicación y la segunda desde un punto de vista teórico-computacional con el fin de elucidar algunas propiedades fisicoquímicas que ayuden a develar la simbiosis de estos materiales. Entre los resultados obtenidos fue posible caracterizar un material con una fase estable que tiene una respuesta electroquímica dentro del rango de los valores hasta ahora reportados en la literatura, ademas de confirmar algunas propiedades relacionadas con su excitación, interacción electrónica y energías de adsorción mediante la teoría de funcionales de densidad.""Y2O3
is the most abundant
chemical component of this rare earth, it has been studied for its ceramic properties,
electro-optics mainly. Nevertheless, recently this metalic oxide have many reports
about the use with carbon materials like graphene oxide for implementation on paste
carbon electrodes in order to evaluate the response in the electrochemical sensing of
drugs. In this work the study of the material from two perspectives is approached. The
first to obtain and characterize a graphene oxide-Y2O3 composite that has good stability
and experimental characteristics for its application and the second from a theoreticalcomputational
point of view in order to elucidate some physicochemical properties that
help unveil the symbiosis of these materials. Among the results obtained, it was possible
to characterize a material with a stable phase that has an electrochemical response
within the range of values reported in literature, in addition to confirming some properties
related to its excitation, electronic interaction and adsorption energies through the
theory of functional density.
Microalga como fuente de biomasa para la producción de biogás
Get PDF"La biomasa microalgal es un sustrato idóneo para la producción de biocombustibles carbono neutrales, que
representan una alternativa al uso de combustibles fósiles, entre ellos se encuentra el biogás. El biogás es una
mezcla de 55-75% (CH4) y 45-25% (CO2) y se obtiene por medio de un proceso denominado digestión
anaerobia. En el caso de la biomasa microalgal, es necesaria la aplicación de un pretratamiento a dicha
biomasa para liberar los compuestos orgánicos susceptibles de convertirse en biocombustible, y así favorecer
el proceso de digestión anaerobia. Cuando la digestión anaerobia se realiza en condiciones alcalinas el
porcentaje de CH4 en el biogás será mayor que el obtenido a pH neutro, debido al equilibrio de fases a pH
alcalino entre el CO2 producido por la DA y su disolución como bicarbonato en el líquido. Por tanto,
resultaría conveniente aplicar un pretratamiento alcalino a la biomasa microalgal y posteriormente realizar la
producción de metano en condiciones alcalinas, y evitar el uso de reactivos para neutralizar el pH de la
biomasa pretratada. Además el acoplamiento de la digestión anaerobia con el cultivo de biomasa microalgal
presenta la capacidad de secuestrar CO2 ya sea atmosférico, del propio biogás o del generado durante su
combustión, así como de reciclar nutrientes (N y P). El presente trabajo tuvo como objetivo determinar la
factibilidad de utilizar biomasa microalgal pretratada en condiciones alcalinas como sustrato para la
producción de biogás. Se evaluaron diferentes pretratamientos termoalcalinos con distintos álcalis y
condiciones de temperatura (NaOH y CaO); además se usó peróxido de hidrógeno alcalino (PHA). Los
pretratamientos se realizaron sobre 2 lotes diferentes de biomasa microalgal de Scenedesmus obtusiusculus.
Después de aplicar los diferentes pretratamientos termoalcalinos, se observó un aumento en la solubilización
de materia orgánica de 10.8 a 19.5% con los diferentes pretratamientos. La digestión anaerobia en
condiciones alcalinas requirió la aclimatación gradual de un lodo a pH 9, la cual se llevó a cabo en un reactor
UASB de 1.25 L con un TRH 27.2 h. Las pruebas de potencial de metano se realizaron con un pH inicial de 9
en donde el rendimiento de producción más alto se obtuvo con PHA 1.5% a 50°C por 1.5 h para el Lote 1 y
con NaOH 4 M a 120°C por 20 min tanto para el Lote 2 de biomasa microalgal (320.6 mL CH4/g SV y 227.1
mL CH4/g SV respectivamente). En cuanto a la velocidad de producción de metano no se encontraron
diferencias significativas (p>0.5) entre la biomasa pretratada y sin pretratar en el Lote 1, para el Lote 2 la
velocidad de producción más alta se obtuvo con NaOH 4M (28.8 mL/g SV·d). El porcentaje de metano
presente en los ensayos de potencial de metano estuvo entre 78 a 100% a pH 9 y no fue necesaria la
neutralización del hidrolizado ya que se contaba con lodo aclimatado a condiciones alcalinas.""Microalgal biomass is an ideal substrate for the production of neutral carbon biofuels, such as biogas, which
represents an alternative to the use of fossil fuels. Biogas is a mixture of 55-75% (CH4) and 45-25% (CO2)
and is obtained by anaerobic digestion. In order to digest the microalgal biomass it is necessary to apply a pretreatment
to release the organic compounds susceptible to be transformed into biofuel, and thus favor the
anaerobic digestion process. If the anaerobic digestion is carried out under alkaline conditions, the CH4
content in the biogas will be higher than that obtained at neutral pH, due to the phase equilibrium reached
between the CO2 produce by the anaerobic digestion and its dissolution as bicarbonate in the liquid phase.
Therefore, it would be convenient to apply an alkaline pretreatment to the microalgal biomass and
subsequently to produce methane under alkaline conditions, and avoid the use of reagents to neutralize the pH
of the pre-treated biomass. Besides the coupling of anaerobic digestion with microalgal biomass culture has
the ability to sequester atmospheric CO2 and CO2 from the combustion process, as well as recycling nutrients
(N and P). The aim of this work was to determine the feasibility of using pre-treated microalgal biomass as a
substrate for the production of biogas under alkaline conditions. Therefore, different thermoalkaline
pretreatments were evaluated with different conditions of temperature and alkalis NaOH and CaO; alkaline
hydrogen peroxide (PHA) was also used for alkaline pretreatment. After applying the different thermoalkaline
pretreatments to two lots of the microalgae Scenedesmus obtusiusculus (1 and 2), an increase in the
solubilization of organic matter was observed from 10.8 to 19.5% with the different pretreatments. Anaerobic
digestion under alkaline conditions required the gradual acclimatization of the anaerobic sludge at pH 9,
which was carried out in a UASB reactor of 1.25 L with a HRT of 27.2 h. The methane potential tests were
performed with an initial pH of 9 where the highest production yield was obtained with PHA 1.5% at 50 °C
for 1.5 h for Lot 1 and with the pretreatment 4 M NaOH at 120 ° C for 20 min for Lot 2 (320.6 mL CH4 / g
SV and 227.1 mL CH4 / g SV respectively). Regarding the rate of methane production, no significant
differences were found (p> 0.5) between pretreated and untreated biomass in Lot 1, for Lot 2 the highest
production rate was obtained with 4M NaOH (28.8 mL/g SV·d). The percentage of methane present in the
methane potential tests varied from 78 to 100% at pH 9 and the neutralization of the hydrolysate was not
necessary because an acclimated inoculum to alkaline pH was used.
Modification of porous nickel electrodes with silver nanoparticles for hydrogen production
Get PDF"Silver nanoparticles were electrodeposited into the surface of a macroporous Ni electrode. The developed electrodes were characterized morphologically by confocal laser scanning microscopy and field emission scanning electron microscopy. The activity of the developed electrodes towards the hydrogen evolution reaction was assessed by pseudo-steady-state polarization curves and electrochemical impedance spectroscopy in alkaline solutions at different temperatures. The incorporation of the silver nanoparticles on the surface of the electrode improved the catalytic activity towards the hydrogen evolution reaction due to an improvement in the electrochemically active surface area rather than in the intrinsic catalytic activity.