842 research outputs found

    H2 production by the photocatalytic reforming of cellulose and raw biomass using Ni, Pd, Pt and Au on titania

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    Here, we report a method for sustainable hydrogen production using sunlight and biomass. It is shown that cellulose can be photoreformed to produce hydrogen, even in solid form, by use of metal-loaded titania photocatalysts. The experiments performed verified that the process is enabled by initial hydrolysis via glucose, which itself is shown to be efficiently converted to produce hydrogen by photocatalysis. Importantly, it is shown that not only precious metals such as Pt, Pd and Au can be used as the metal component, but also much more economic and less environmentally damaging Ni is effective. Even more importantly, we show for the first time, to the best our knowledge, that fescue grass as raw biomass can be effective for hydrogen production without significant pretreatment. This provides additional benefits for the efficiency of biomass hydrogen production, because fewer processing steps for the raw material are required than in the production of purer forms of cellulose, for example

    Academic Burnout, Personality, and Academic Variables in University Students

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    This study examines academic burnout syndrome and its relation to personal and academic variables among university students in nursing and early childhood education programs in Spain. A total of 606 university students (primary education: 49.7%; nursing: 49.7%) of both sexes (71.5% female) with an average age of 20.68 years (SD = 1.65) participated. An ex post facto retrospective single-group design was planned. The instruments used were the Maslach Burnout Inventory-Student Survey (MBI-SS) and the NEO Five-Factor Inventory (NEO-FFI). Nursing students, who reported more study hours, less sleep, and lower grades, had higher academic burnout scores. Linear regression models were proposed to analyze the relationship between academic burnout, personality, and sociodemographic variables. Nursing students scored higher in emotional exhaustion and lower in cynicism, and they scored higher in neuroticism and openness. Furthermore, 16.1% of the variance in academic burnout was explained by personality variables as well as the degree studied, course year, and study hours. These findings suggest the importance of considering both academic and personality variables in understanding academic burnout in university students

    Microparticle movements in optical funnels and pods

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    Three-dimensional microparticle movements induced by laser beams with a funnel-and tubular pod-like structure, in the neighbourhood of the focal plane of an optical trapping setup, are experimentally studied. The funnel and pod beams constructed as coherent superpositions of helical Laguerre-Gaussian modes are synthesized by a computer generated hologram using a phase-only spatial light modulator. Particle tracking is achieved by in-line holography method which allows an accurate position measurement. It is experimentally demonstrated that the trapped particle follows different trajectories depending on the orbital angular momentum density of the beam. In particular applying the proposed pod beam the particle rotates in opposite directions during its movement in the optical trap. Possible applications of these single-beam traps for volumetric optical particle manipulation are discussed. © 2011 Optical Society of America.The financial support of the Spanish Ministry of Science and Innovation under projects TEC2008-04105, TEC2009-5545-E/TEC are acknowledged. J. A. Rodrigo and A. M. Caravaca-Aguirre gratefully thank a “Juan de la Cierva” grant and fellowship from “Obra Social Ibercaja (Beca Ibercaja de Investigación 2010)”, respectively. The authors appreciate valuable comments from J. R. Arias-González.Peer Reviewe

    Nutritional and functional advantages of the use of fermented black chickpea flour for semolina-pasta fortification

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    Pasta represents a dominant portion of the diet worldwide and its functionalization with high nutritional value ingredients, such as legumes, is the most ideal solution to shape consumers behavior towards healthier food choices. Aiming at improving the nutritional quality of semolina pasta, semi-liquid dough of a Mediterranean black chickpea flour, fermented with Lactiplantibacillus plantarum T0A10, was used at a substitution level of 15% to manufacture fortified pasta. Fermentation with the selected starter enabled the release of 20% of bound phenolic compounds, and the conversion of free compounds into more active forms (dihydrocaffeic and phloretic acid) in the dough. Fermented dough also had higher resistant starch (up to 60% compared to the control) and total free amino acids (almost 3 g/kg) contents, whereas antinutritional factors (raffinose, condensed tannins, trypsin inhibitors and saponins) significantly decreased. The impact of black chickpea addition on pasta nutritional, technological and sensory features, was also assessed. Compared to traditional (semolina) pasta, fortified pasta had lower starch hydrolysis rate (ca. 18%) and higher in vitro protein digestibility (up to 38%). Moreover, fortified cooked pasta, showing scavenging activity against DPPH and ABTS radicals and intense inhibition of linoleic acid peroxidation, was appreciated for its peculiar organoleptic profile. Therefore, fermentation technology appears to be a promising tool to enhance the quality of pasta and promote the use of local chickpea cultivars while preventing their genetic erosion

    Environmental changes and radioactive traces

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    Análisis del espesor coroideo en pacientes con queratocono

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    Objective. To determine and compare choroidal thickness (CT) in keratoconus (KC) patients using Enhanced Depth Imaging (EDI) OCT. Methods. A comparative cross-sectional study including 26 patients with KC and 26 healthy controls assessed with Pentacam and EDI-OCT. CT was measured manually with the Caliper function at thirteen locations at 500 µm regular intervals. Results. The average CT in T6 was 253.96 ± 88.95 μm in the KC group, and of 309.39 ± 94.11 μm in the control group (p <0.041). No significant differences in mean CT were observed in the rest of the points, including the subfoveal CT (M), 351.48 ± 106.3 vs 365.35 ± 114.6 μm, (p = 0.66). No correlation was observed between the mean subfoveal CT (M), the mean CT in the KC group, and the values of K1 (p = 0.977 and p = 0.498 respectively), K2 (p = 0.450 and p = 0.656), corneal asphericity (Q ) (p = 0.986 and p = 0.902), minimal pachymetry (Pachy) (p = 0.408 and p = 0.688), keratoconus index (KI) (p = 0.601 and p = 0.217), vertical asymmetry index (VAT) (p = 0.296 and p = 0.523), staging of KC (TKC) (p = 0.549 and p = 0.08) and corneal apex morphology. Conclusion. Significant lower CT was found in the KC group in T6 (3000 μm temporal to the fovea). No significant difference of CT values in KC patients and healthy subjects was found in the other twelve measurement locations.We found no association between the refractive and keratometric indexes obtained by corneal topography and subfoveal CT.Objetivo. Determinar y comparar el grosor de la coroides (CT) en pacientes con queratocono (KC) usando OCT con Enhanced Depth Imaging (EDI). Métodos. Estudio comparativo transversal que incluye 26 pacientes con KC y 26 controles sanos evaluados con Pentacam y EDI-OCT. El KC fue medido manualmente con la función Caliper en trece puntos a intervalos regulares de 500 µm. Resultados. El promedio de CT en T6 fue de 253,96 ± 88,95 μm en el grupo KC, y de 309,39 ± 94,11 μm en el grupo de control (p <0,041). No se observaron diferencias significativas en la media de CT en el resto de los puntos, incluyendo el CT subfoveal (M), 351.48 ± 106.3 vs 365.35 ± 114.6 μm, (p = 0.66). No se observó ninguna correlación entre la media de CT (M) subfoveal, la media de CT en el grupo KC, y los valores de K1 (p = 0,977 y p = 0,498 respectivamente), K2 (p = 0,450 y p = 0,656), la asfericidad corneal (Q) (p = 0,986 y p = 0. 902), paquimetría mínima (Pachy) (p = 0,408 y p = 0,688), índice de queratocono (KI) (p = 0,601 y p = 0,217), índice de asimetría vertical (VIA) (p = 0,296 y p = 0,523), estadificación del KC (TKC) (p = 0,549 y p = 0,08) y morfología del ápice corneal. Conclusión. Se observó un CT significativamente menor en el grupo KC en T6 (3000 μm temporal a la fóvea). No se encontraron diferencias significativas entre los valores del CT en los pacientes con KC y en los sujetos sanos en los 12 puntos de medida restantes. No se encontró ninguna asociación entre los índices refractivos y queratométricos obtenidos por la topografía corneal y el CT subfoveal

    HPLC-DAD-ESI-QTOF-MS and HPLC-FLD-MS as valuable tools for the determination of phenolic and other polar compounds in the edible part and by-products of avocado

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    Avocado is a tropical fruit increasingly cultivated around the world due to global interest and rising consumption. Thus, there is also a surge in avocado by-products that needs assessment. The aim of this work is to compare the phenolic profile of avocado pulp, peel and seed when the fruit is at optimal ripeness for consumption and when overripe. Two analytical techniques were used: (1) HPLC-DAD-ESI-QTOF-MS was used for the first time to determine phenolic and other polar compounds in avocado peel and seed. Phenolic compounds quantified with these methods were in higher concentration in overripe than in pulp and seed of optimally ripe fruit. (2) HPLC-FLD-MS was used to specifically determine flavan-3-ols. Procyanidins to degree of polymerization 13 have been quantified singularly here for the first time. In addition, A- and B-type procyanidins from the degree of polymerization 2 to 6 were differentiated and quantified. The procyanidin concentration increased after ripening probably due to the release of tannins linked to cell-wall structures. Because of this situation and the presence of A-type procyanidins, avocado peel and seed from overripe fruit, the main by-products of avocado processing, hold interest for developing functional foods, nutraceuticals and cosmetics

    Estudio de estabilidad de complejos atómicos en semiconductores del grupo IV mediante el modelo de Keating Anarmónico

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    Se presenta un estudio de energías de configuración de pequeños clusters de átomos de C, Ge y Sn en Si para posiciones sustitucionales, mediante el modelo de Keating anarmónico. Los resultados muestran en general tendencia a la nucleación excepto Cx en Si y una posible formación de estructuras complejas de 4 átomos en Si 158 - xGe C

    Evolution des exploitations ovines et caprines en Méditerranée durant les dix dernières années. I. Proposition d'une méthodologie d'étude

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    L’objectif de ce travail est l’élaboration d’une méthode d’analyse comparative interrégionale de la situation et des évolutions des systèmes de production ovine et caprine. Des questionnaires d’enquête différents sont élaborés à destination des éleveurs d’une part, des agents de développement puis des personnes chargées de la commercialisation d’autre part. Des analyses statistiques de variance sont utilisées pour construire des typologies d’exploitation sur la base de la situation actuelle et de l’évolution des exploitations au cours des 10 dernières années. La méthode d’analyse clinique des écosystèmes a pour objet : (i) de connaître les points forts et les points faibles des systèmes et les relations de cause à effet ; (ii) de prévoir de manière prospective l’évolution future de chaque type d’exploitation ; et (iii) de proposer des actions concrètes pour optimiser les perspectives favorables de chaque système. Cette démarche s’inscrit dans l’Observatoire des systèmes de production ovine et caprine du réseau FAO/CIHEAM de recherche coopérative sur les ovins et les caprins.“Evolution of the sheep and goat farms in the Mediterranean over the last ten years. I. Proposal of a study methodology”. The main objective of this paper is to develop a methodology that could be used in diverse regions to make a comparative analysis of situation and changes that may occur in goat and sheep sectors among different regions from the same or different countries. This process has been elaborated for breeders on one hand, for extension and commercial agents on the other. Statistical analysis of variance is used to build up a typology of farms on the basis of the actual situation and changes in farms for the 10 last years. The method of clinical analysis of variance of ecosystems is used to: (i) determine system strengths and weaknesses and the cause-result relationships; (ii) foresee system evolution based on the established cluster; and (iii) propose actions to optimize future evolution in every system according to real possibilities in each particular case. This initiative is an action of the Monitoring Body of sheep and goat production systems of the FAO/CIHEAM network of cooperative research on sheep and goats
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