Degradación de rojo congo en un fotorreactor tubular de tecnología excimer. Estudio cinético

Como ampliación al estudio realizado sobre la fotodegradación de rojo congo con lámparas discontinuas de tecnologíaexcimer de XeBr, KrCl y Cl2, en este trabajo se ha estudiado la fotodegradación de dicho colorante mediante un fotorreactor continuo de KrCl, con recirculación, con H2O2 y con reactivo Fenton. Del estudio de la influencia de las condiciones de operación, se han seleccionado los valores de caudal y de concentración inicial de rojo congo óptimos para su degradación. Adicionalmente, se ha comprobado que la degradación de rojo congo mejora al aumentar la cantidad de H2O2 adicionada al medio hasta una relación molar H2O2: rojo congo de 75:1 a partir de la cual ya no aumenta más. Además, la fotodegradación de rojo congo también se ve favorecida al aumentar la concentración de Fe2+ al utilizar el reactivo Fenton.El modelo modificado de pseudo primer orden propuestopreviamente se ha aplicado a este tipo de reactor. Delajuste del modelo, se ha obtenido la tendencia de la constantede velocidad (k), para las diferentes series experimentales.Además, los valores calculados con el modelopara la conversión de rojo congo se han comparado conlos experimentales, obteniéndose un buen ajuste lineal.Finalmente, se ha realizado un análisis ANOVA confirmándosela validez del modelo

Spectral Reconstruction and Noise Model Estimation Based on a Masking Model for Noise Robust Speech Recognition

An effective way to increase noise robustness in automatic speech recognition (ASR) systems is feature enhancement based on an analytical distortion model that describes the effects of noise on the speech features. One of such distortion models that has been reported to achieve a good trade-off between accuracy and simplicity is the masking model. Under this model, speech distortion caused by environmental noise is seen as a spectral mask and, as a result, noisy speech features can be either reliable (speech is not masked by noise) or unreliable (speech is masked). In this paper, we present a detailed overview of this model and its applications to noise robust ASR. Firstly, using the masking model, we derive a spectral reconstruction technique aimed at enhancing the noisy speech features. Two problems must be solved in order to perform spectral reconstruction using the masking model: (1) mask estimation, i.e. determining the reliability of the noisy features, and (2) feature imputation, i.e. estimating speech for the unreliable features. Unlike missing data imputation techniques where the two problems are considered as independent, our technique jointly addresses them by exploiting a priori knowledge of the speech and noise sources in the form of a statistical model. Secondly, we propose an algorithm for estimating the noise model required by the feature enhancement technique. The proposed algorithm fits a Gaussian mixture model to the noise by iteratively maximising the likelihood of the noisy speech signal so that noise can be estimated even during speech-dominating frames. A comprehensive set of experiments carried out on the Aurora-2 and Aurora-4 databases shows that the proposed method achieves significant improvements over the baseline system and other similar missing data imputation techniques

Assessment of Cutting Tool Condition by Acoustic Emission

AbstractAcoustic emission (AE) signals, generated during the machining of steel, were analyzed in order to extract information about the condition of the cutting tool. Drill bits with different cutting edge conditions were used to drill steel specimens while registering the AE generated during cutting. Artificial wear of the drill bits was produced by spark erosion and by mechanical means and was assessed by scanning electron microscopy (SEM). During cutting typical parameters and waveforms of AE and torque were recorded. The relationship between MARSE (Measured Area under the Rectified Signal Envelope) Mean Power (MP) and torque was studied for the different conditions of the drill bits. The evolution of the mobile variance of MP in terms of its moving average was also analyzed with interesting results for determining the condition of the tool. Furthermore, the waveform of AE signals was evaluated through the power spectrum and, from these and from previous results, it was possible to separate the contributions to MP from different AE sources

Extrapolating demography with climate, proximity and phylogeny: approach with caution

Plant population responses are key to understanding the effects of threats such as climate change and invasions. However, we lack demographic data for most species, and the data we have are often geographically aggregated. We determined to what extent existing data can be extrapolated to predict population performance across larger sets of species and spatial areas. We used 550 matrix models, across 210 species, sourced from the COMPADRE Plant Matrix Database, to model how climate, geographic proximity and phylogeny predicted population performance. Models including only geographic proximity and phylogeny explained 5-40% of the variation in four key metrics of population performance. However, there was poor extrapolation between species and extrapolation was limited to geographic scales smaller than those at which landscape scale threats typically occur. Thus, demographic information should only be extrapolated with caution. Capturing demography at scales relevant to landscape level threats will require more geographically extensive sampling

Evaluation of the presence of Vibrio parahaemolyticus in white shrimp (Litopenaeus vannamei) estuarine-wild from southern Sinaloa and northern Nayarit by microbiological analysis and PCR

Given the incidence of human poisonings attributed to raw shrimp consumption in southern of Sinaloa and northern of Nayarit in recent years, white shrimp (Litopenaeus vannamei) was sampled from three wildestuaries where it’s been captured and one sample was taken from a sale center in order to determine the possible presence of toxigenic Vibrio parahaemolyticus, from May to December of 2012. Samples were analyzed by Biochemical test and Polymerase Chain Reaction (PCR), they were also tested for the specific an toxicological identification, using molecular oligo nucleotides markers tlh, tdh and trh. The number of positives results were recorded to a table of most probable number (MPN).The number of samples positive for V. parahaemolyticus, weren’t toxigenic and it was demonstrated that they were below the limit established in the Mexican Official Standard NOM-242-SSA1-2009. In conclusion, the present study revealed that consumption of raw shrimp from the dates and sites sampled did not show to be a risk for human gastrointestinal diseases

First-order quasilinear canonical representation of the characteristic formulation of the Einstein equations

We prescribe a choice of 18 variables in all that casts the equations of the fully nonlinear characteristic formulation of general relativity in first--order quasi-linear canonical form. At the analytical level, a formulation of this type allows us to make concrete statements about existence of solutions. In addition, it offers concrete advantages for numerical applications as it now becomes possible to incorporate advanced numerical techniques for first order systems, which had thus far not been applicable to the characteristic problem of the Einstein equations, as well as in providing a framework for a unified treatment of the vacuum and matter problems. This is of relevance to the accurate simulation of gravitational waves emitted in astrophysical scenarios such as stellar core collapse.Comment: revtex4, 7 pages, text and references added, typos corrected, to appear in Phys. Rev.

Ordenadores en el aula: ¿estamos preparados los profesores?

Integrar les TIC a les aules de Física i Química suposa un gran repte i els factors involucrats són molts i complexos. El problema fonamental rau en com s'utilitzen les TIC per part dels estudiants i, en això, tenen un paper molt important l'escola i l'ús que els professors fan d'elles. Hem realitzat una investigació amb 138 professors de Física i Química per analitzar com utilitzen les TIC en el seu treball d'aula, la percepció que tenen sobre com les utilitzen seus alumnes i les dificultats que sorgeixen en tractar i integrar les TIC en el treball d'aula. Els resultats mostren que les TIC s'utilitzen poc i que el seu ús genera incertesa en molts professors, per el que es pot concloure que cal una formació que faciliti la seva integració a les aules.Integrating Information and Communication Technology (ICT) into Physics and Chemistry classroom poses an important challenge. Factors involved are numerous and complex. The key problem is how the students use ICT and their high-schools and the use that teachers make of these technologies in the classroom play a fundamental role. Research was carried out with 138 Physics and Chemistry teachers in order to analyze how they include ICT in their classroom work, their perception about how the students use ICT and the difficulties that arise when trying to incorporate it to their daily work. The results indicate that ICT is slightly integrated into the classroom work and that their use generates uncertainty in many teachers. It can be concluded that appropriate training of the teachers to facilitate their use in classroom is required.Integrar las TIC en las aulas de Física y Química supone un gran reto y los factores involucrados son muchos y complejos. El problema fundamental radica en cómo se utilizan las TIC por parte de los estudiantes y, en esto, tienen un papel muy importante la escuela y el uso que los profesores hacen de ellas. Hemos realizado una investigación con 138 profesores de Física y Química para analizar cómo utilizan las TIC en su trabajo de aula, la percepción que tienen sobre cómo las utilizan sus alumnos y las dificultades que surgen al tratar e integrar las TIC en el trabajo de aula. Los resultados muestran que las TIC se utilizan poco y que su uso genera incertidumbre en muchos profesores, por lo que se puede concluir que es necesaria una formación que facilite su integración en las aulas

Effects of foliar versus soil water application on ecophysiology, leaf anatomy and growth of pineapple

In the subtropics, pineapple [Ananas comosus (L.) Merr.] can be grown in plastic greenhouses to avoid low temperature, which is the main limiting factor to production outside of the tropics. Foliar water application and subsequent evaporative cooling can help avoid excessive leaf temperatures in greenhouses during the hot seasons. The effects of foliar versus soil irrigation on ecophysiology, leaf anatomy and leaf temperature of pineapple in protected culture were tested to determine if the crop could receive sufficient irrigation to avoid plant stress solely from misting the foliage. Materials and methods - Relative water content, relative chlorophyll content, normalized difference vegetation index, membrane stability, and cross sectional leaf anatomy were measured at periodic intervals. Pineapple plants were subjected to soil irrigation, misting and drought. At the beginning and at the end of the experiment, total leaf area, plant biomass and assimilate partitioning to leaves, stems and roots were measured. Results and discussion - The normalized difference vegetation index revealed differences among treatments after fifteen days without irrigation. Pineapple plants endured thirty days of water stress without membrane damage. Plants irrigated by applying water only to the leaves did not receive adequate water amounts and showed similar signs of drought stress as those of the non-irrigated treatment. Conclusion - Based on ecophysiological, anatomical and growth responses, soil water application alone is sufficient for avoiding water stress and excessively high leaf temperatures of pineapple plants grown in protected culture in the subtropics, whereas only misting the leaves does not provide adequate water supply to prevent water stress.Fil: Demarco, Paula. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Departamento de Produccion Vegetal.; ArgentinaFil: Gómez Herrera, Melanie Desirée. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Química Básica y Aplicada del Nordeste Argentino. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Química Básica y Aplicada del Nordeste Argentino; ArgentinaFil: Gonzalez, A.M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Alayón Luaces, Paula. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Departamento de Produccion Vegetal.; Argentin

Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV

Quasi-elastic scattering of 6He at E_lab=27 MeV from 197Au has been measured in the angular range of 6-72 degrees in the laboratory system employing LEDA and LAMP detection systems. These data, along with previously analysed data of 6He + 208Pb at the same energy, are analyzed using Optical Model calculations. The role of Coulomb dipole polarizability has been investigated. Large imaginary diffuseness parameters are required to fit the data. This result is an evidence for long range absorption mechanisms in 6He induced reactions.Comment: 10 pages, 10 figures, minor corrections. To appear in Nucl. Phys.