Consejos amigables a Don Diego de Torres...

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Fecha y lugar de imp. tomadas de licenciaPort. con orla tip

Solar image denoising with convolutional neural networks

The topology and dynamics of the solar chromosphere are greatly affected by the presence of magnetic fields. The magnetic field can be inferred by analyzing polarimetric observations of spectral lines. Polarimetric signals induced by chromospheric magnetic fields are, however, particularly weak, and in most cases very close to the detection limit of current instrumentation. Because of this, there are only few observational studies that have successfully reconstructed the three components of the magnetic field vector in the chromosphere. Traditionally, the signal-to-noise ratio of observations has been improved by performing time-averages or spatial averages, but in both cases, some information is lost. More advanced techniques, like principal-component-analysis, have also been employed to take advantage of the sparsity of the observations in the spectral direction. In the present study, we propose to use the spatial coherence of the observations to reduce the noise using deep-learning techniques. We design a neural network that is capable of recovering weak signals under a complex noise corruption (including instrumental artifacts and non-linear post-processing). The training of the network is carried out without a priori knowledge of the clean signals, or an explicit statistical characterization of the noise or other corruption. We only use the same observations as our generative model. The performance of this method is demonstrated on both, synthetic experiments and real data. We show examples of the improvement in typical signals obtained in current telescopes such as the Swedish 1-meter Solar Telescope. The presented method can recover weak signals equally well no matter on what spectral line or spectral sampling is used. It is especially suitable for cases when the wavelength sampling is scarce.Comment: 13 pages; accepted for publication in A&

Simultaneous determination of iron and copper using screen-printed carbon electrodes by adsorptive stripping voltammetry with o-phenanthroline.

The simultaneous voltammetric determination of iron and copper was accomplished by an unmodified screen-printed carbon electrode based on the complexation with o-phenanthroline assisted by the reducing agent ferrocyanide. The detection limits were 3.74 and 0.34 µg L−1 for iron and copper, respectively, and a linear response was observed from 12.5 to 400 µg L−1 for iron and from 1.14 to 400 µg L−1 for copper. This method successfully avoids interferences between iron and copper while allowing the simultaneous determination of both low and high metal concentrations usually found in the environment. Finally, a certified wastewater reference material was successfully analyzed, confirming the precision and accuracy of the proposed method

Chitosan coating surface properties as affected by plasticizer, surfactant and polymer concentrations in relation to the surface properties of tomato and carrot

The objectives of this work were to determine the effects of the concentrations of glycerol and sorbitol (as hydrophilic plasticizers), Tween 80 (as surfactant) and chitosan on the wettability of Cuban chitosan-based edible coatings in view of their application on tomato and carrot and to develop a model allowing the optimization of coating composition. The values of the polar and dispersive components of the superficial tension of the foods were determined to be 3.04 and 25.67 mN/m, respectively, for tomato, and 0.34 and 26.13 mN/m, respectively, for carrot, the sum of the two components being the superficial tensions of tomato and carrot (28.71 and 26.48 mN/m, respectively). The skins of both foods are therefore low-energy surfaces, meaning that the Zisman method for the determination of wettability could be applied. The best experimental values of wettability were obtained for the following coating composition: 1.5% (w/v) of chitosan and 0.1% (w/w) of Tween 80. The increase in the concentration of chitosan and glycerol or sorbitol as plasticizers decreased the values of wettability and adhesion coefficients. The results of wettability were adjusted to a polynomial model that describes the dependence of the adhesion coefficient (Wa), cohesion coefficient (Wc) and spreading coefficient (Ws) on chitosan and Tween 80 concentrations. The optima calculated by the model equations were in excellent agreement (relative error below 3%) with the experimental values.Coordenação Aperfeicoamento de Pessoal de Nível Superior (CAPES, Brazil).aLFA VALNATURA Project of Europe Aid Cooperation Office

Chitosan coating surface and permeation properties as affected by plasticizer, surfactant and polymer concentration-application to vegetables

Edible coatings can act as moisture, lipid, and gas barriers and can improve the textural properties of foods or serve as carriers of functional agents such as colors, flavors, antioxidants, nutrients and antimicrobials. The objectives of this work were to study the potentialities of chitosan (obtained from lobster of the cuban coasts) coating to extend the shelf life of fruits. To do so, the surface properties of tomato and carrot were characterized and the wettability properties of chitosan edible coatings were studied. In such coatings, parameters such as chitosan concentration and effects of type and concentration of hydrophilic plasticizer or surfactant on wettability of chitosan coatings were evaluated, as well as the respective barriers properties to gases. It was possible to determine the values of the polar and dispersive components of the superficial tension, that are 3.32 and 25.24 mN/m, respectively, for the tomato and 0.48 and 25.62 mN/m, respectively, for the carrot; being the superficial tensions of the tomato and carrot the sum of the two components (28.55 and 26.40 mN/m) respectively. Both are therefore, low energy surfaces. The results of wettability determinations allowed to adjust one factorial model that suggests an increase of the spreading coefficient as the chitosan concentration decreases and Tween concentration increases. The best values of wettability correspond to the following coating composition: 1.5 % (w/v) of chitosan and 0.1 % (w/w) of Tween 80. A correlation has been found between the water vapor, oxygen and carbon dioxide permeability coefficients, and glycerol concentration (while keeping Tween and chitosan concentrations constant). In the absence of glycerol, a decreased permeability to the gases was observed. An increase of the chitosan concentration decreases a lightness and increase yellow color of coatings. The chitosan coatings with glycerol showed high values lightness and were more transparent and yellowier than those without glycerol

Chitosan coating and films : evaluation of surface, permeation, mechanical and thermal propertiess

The potentialities of chitosan (from lobster of the cuban coasts) coating to extend the shelf life of vegetables were evaluated. To do so, the surface properties of tomato and carrot were characterized and the wettability properties of chitosan coatings were studied. In such coatings, chitosan concentration and effects of type and concentration of plasticizer or surfactant on wettability of chitosan coatings were evaluated, as well as the respective barrier and mechanical properties. Additionally, a blend of chitosan and clay microparticles was performed and the films obtained were characterized in terms of barrier, mechanical and thermal properties. The values of the polar and dispersive components of the superficial tension for the tomato and the carrot were determined, being the superficial tensions of the tomato and carrot 28.55 and 26.40 mN/m, respectively. The results of wettability determinations allowed the construction of one factorial model. The best values of wettability correspond to the following coating composition: 1.5 % (w/v) of chitosan and 0.1 % (w/w) of Tween 80. Acorrelation has been found between the gas permeability coefficients and chitosan concentration (while keeping Tween concentrations constant). The water vapour barrier property of the chitosan films was significantly improved by incorporation of clay, the tensile strength increased significantly with increasing chitosan and clay concentrations, while the values of elongation decreased slightly for high values of chitosan concentration. The obtained models are meant to predict the properties of chitosan/clay films to be prepared.Las potencialidades del empleo de coberturas de quitosana (obtenida a partir de langosta) para extender la vida de anaquel de los vegetales fueron evaluadas. En este sentido fueron determinadas las propiedades de superficie del tomate y la zanahoria y el efecto de la concentración de polímero, tipo y concentración de plastificante, así como la concentración de agente surfactante sobre la humectabi-lidad de las coberturas de quitosana. Las coberturas que mostraron mejor humectabilidad fueron ca-racterizadas en relación a sus propiedades de barrera y mecánicas. Adicionalmente fueron obtenidas películas de quitosana/arcilla y caracterizadas sus propiedades de barrera, mecánicas y térmicas Los valores de las componentes polar y dispersiva de la tensión superficial del tomate y la zanahoria fueron determinados, siendo la tensión superficial de los mismos 28.55 y 26.40 mN/m, respectivamente. Los resultados de las determinaciones de humectabilidad se ajustaron a un modelo factorial. Los mejores valores en términos de humectabilidad correspondieron a la cobertura con una composición de: quitosana 1.5% (m/v) y 0.1 % (m/v) de Tween 80. Una incidencia de la concentración de quitosana (concentración de Tween constante) sobre las propiedades mecánicas y de barreras de las coberturas fue encontrada. La permeabilidad al vapor de agua de las películas de quitosana fue significativamente mejorada con la adición de arcilla en su composición. El esfuerzo tensil aumentó significativamente con el aumento de la concentración de quitosana y arcilla, mientras que la elongación disminuyó ligeramente. Los modelos obtenidos permiten predecir las propiedades de las películas de quitosana/arcilla que se quie-ran preparar

Occurrence of pharmaceuticals and personal care products in the urban aquifer of Zaragoza (Spain) and its relationship with intensive shallow geothermal energy exploitation

A steady increase in the consumption of pharmaceuticals and personal-care products worldwide is increasing their occurrence in the biosphere. The current study describes the abundance of 42 selected emerging organic contaminants (EOCs), including human and veterinary antibiotics, UV-filters and analgesics in the groundwater of the urban aquifer of Zaragoza (Spain), which is affected by intensive exploitation of shallow geothermal resources. The presence of groundwater heat pump systems in the aquifer studied offered the opportunity to study the occurrence of EOCs in relation to groundwater temperature and other physicochemical effects derived from this technology. Analysis of the data obtained allowed us to identify statistically significant relationships between the presence of EOCs and temperature, as well as other physicochemical and geochemical properties of groundwater. The results obtained suggest that temperature is a minor factor controlling the degradation of the organic compounds analysed compared to the oxygen input from groundwater heat pump systems which is possibly increasing the aerobic redox conditions, thus preventing the degradation of organic pollutants. Intensive use of shallow geothermal resources therefore seems to contribute in the prevalence of such compounds in the aquifer close to geothermal systems

Mass matrix Ansatz and lepton flavor violation in the THDM-III

Predictive Higgs-fermion couplings can be obtained when a specific texture for the fermion mass matrices is included in the general two-Higgs doublet model. We derive the form of these couplings in the charged lepton sector using a Hermitian mass matrix Ansatz with four-texture zeros. The presence of unconstrained phases in the vertices phi-li-lj modifies the pattern of flavor-violating Higgs interactions. Bounds on the model parameters are obtained from present limits on rare lepton flavor violating processes, which could be extended further by the search for the decay tau -> mu mu mu and mu-e conversion at future experiments. The signal from Higgs boson decays phi -> tau mu could be searched at the large hadron collider (LHC), while e-mu transitions could produce a detectable signal at a future e mu-collider, through the reaction e mu -> h0 -> tau tau.Comment: 17 pages, 9 figure

Considerations on the use of spectroelectrochemistry in reflection mode for quantitative analysis: Study of the Fe(III)/Fe(II) - orthophenanthroline system

Theoretical and experimental considerations are made about possible analytical applications of spectroelectrochemistry (SEC) in reflection mode using screen-printed electrodes. The system Fe(III)/Fe(II) - orthophenanthroline is taken as a model of electrochemical generation and consumption of a substance that is strongly absorbing: the Fe(II) - orthophenanthroline complex. Different possibilities of quantification are discussed, including cathodic and anodic peaks in cyclic voltammetry and both electrochemical and optical signals acquired in chronoamperometric experiments. Among these, the evolution of absorbance with the square root of time at a constant potential has shown interesting possibilities for the determination of Fe(III)-ion at micromolar level (LOD = 2 10-6 mol L-1). Moreover, this method appears to be resistant to the presence of other electroactive species such as Cu(II)-ions