Fabrication of bismuth-based photocatalytic heterojunctions for hydrogen generation

Das schnelle Bevölkerungswachstum und die Industrialisierung der letzten Jahrzehnte haben zu einer zunehmenden Umweltverschmutzung und einer hohen Nachfrage nach nicht erneuerbaren Energiequellen aus fossilen Brennstoffen geführt. Wasserstoff ist ein sauberer Energieträger, der aus der Dissoziation von Wasser und Sonnenenergie, einer erneuerbaren Quelle, gewonnen werden kann. Seit der Entdeckung der Wasserstoffentwicklung durch photoelektrochemische Wasserspaltung an n-Typ-TiO2-Elektroden wird die auf Halbleitern basierende photokatalytische Wasserspaltungstechnologie zur Erzeugung von Wasserstoff mit Hilfe von Sonnenenergie als einer der wichtigsten Ansätze zur Lösung der globalen Energiekrise angesehen. Die Entwicklung von Halbleiter-Photokatalysatoren ist daher in letzter Zeit Gegenstand erheblicher Forschungsanstrengungen gewesen. Die Synthese neuer, im sichtbaren Licht aktiver Photokatalysatoren mit hoher photokatalytischer Effizienz ist eine der größten Herausforderungen, bei der das Hauptproblem die schnelle Elektron-Loch-Rekombination ist. Das Design und die Herstellung von halbleitenden Heteroübergängen stellen eine Lösung für den Ladungsträgertransfer und die Trennung dar, um Reduktions- und Oxidationsreaktionen für die H2-Produktion zu erreichen. In der vorliegenden Arbeit wurden mit sichtbarem Licht betriebene Wismut-Heteroübergänge, die durch mechanisches Fräsen und thermisches Flammspritzen hergestellt wurden, für die photokatalytische Entwicklung von H2 in Gegenwart von Opferstoffen eingesetzt. Die Wirkung der Verarbeitungsparameter führte zu strukturellen Veränderungen, z.B. Gitterparameter, Kristallitgröße und Bindungsenergie, und damit zu Veränderungen ihrer optischen Eigenschaften, z.B. des Photolumineszenzsignals und der Bandlückenenergie, um die Oberflächenmodifikation und die Kopplung zwischen Halbleitern zu verstehen. Die Analyse der physikalisch-chemischen Eigenschaften dient dazu, den gewünschten Weg zur Synthese von Bi-basierten Heteroübergängen zu finden, die eine niedrige photogenerierte Elektron-Loch-Paar-Rekombination und eine hohe Absorption im sichtbaren Bereich des Sonnenspektrums nachahmen. In dieser Arbeit schlagen wir photokatalytische Reaktionsmechanismen für die H2-Evolution vor, die auf dem Bandkantenpotential jedes Halbleiters, der Bestimmung der photogenerierten Ladungsträger und der Erzeugung freier Radikale, gemessen durch paramagnetische Elektronenspektroskopie, basieren. Die Ergebnisse zeigen, dass der Aufbau eines Heteroübergangs in einer gestaffelten Technik wünschenswert ist, um den Ladungsträgertransfer und die Trennung zu verbessern. Die Stabilität des Halbleiters und einige physikochemische Eigenschaften wie Partikelgröße und Oberfläche dienen dazu, die Aktivität des Materials zu verbessern.Rapid population growth and industrialization in recent decades has led to increased environmental pollution and a high demand for non-renewable energy sources from fossil fuels. Hydrogen is a clean energy fuel that can be obtained from the dissociation of water and solar energy, a renewable source. Since the discovery of hydrogen evolution through photoelectrochemical water splitting on n-type TiO2 electrodes, semiconductor-based photocatalytic water splitting technology to produce hydrogen using solar energy has been considered as one of the most important approaches to solve the global energy crisis. Therefore, the development of semiconductor photocatalysts has recently been the subject of considerable research efforts. The synthesis of new visible-light active photocatalysts with high photocatalytic efficiencies is one of the main challenges in which the major problem is the fast electron-hole recombination. The design and fabrication of semiconducting heterojunctions represent a solution to address charge carrier transfer and separation to achieve reduction and oxidation reactions for H2 production. In the present work, visible light driven bismuth heterojunctions synthesized by mechanical milling and flame thermal spraying process were employed for the photocatalytic evolution of H2 in the presence of sacrificial agents. The effect of processing parameters induced structural modifications, for instance, lattice parameter, crystallite size, binding energy and thus led to changes in their optical properties, for instance, photoluminescence signal and band gap energy, to understand the surface modification and coupling between semiconductors. The analysis of physicochemical properties serves to achieve a desired route to synthesize Bi-based heterojunctions that lead to low photogenerated electron-hole pair recombination and high absorbance in the visible range of the solar spectrum. In this work, we propose photocatalytic reaction mechanisms for H2 evolution based on the band edge potential of each semiconductor, the determination of photogenerated charge carriers and free radical generation measured by electron paramagnetic spectroscopy. The results show that the construction of a heterojunction in a staggered engineering is desirable to improve charge carrier transfer and separation. The stability of the semiconductor and some physicochemical properties such as particle size and surface area serve to enhance the activity of the material

Measuring inequality and dependences between income sources with administrative data and survey data

Producción CientíficaThis paper aims at analyzing the effects of changing from survey to administrative data on inequality and its structure. Taking advantage of the Spanish Survey on Income and Living Conditions (ECV) that continued asking households for their income despite assigning them the income data provided by the Tax Agency and the Social Security administration, different analyses are carried out. By using copula functions we pay special attention to the effect on the dependences between income sources. We find a significant growth in the disposable income of households when using administrative data. The incomes of both tails of the distribution increase considerably more than middle incomes, and administrative data produce significantly lower levels of inequality. Using administrative instead of survey data also gives rise to changes in the structure of inequality by income sources, rising the contribution of capital income. Both methods of data collection also produce significant differences in the observed dependences between income sources.Economía Aplicad

Defensor del pueblo

Sección C) Los derechos humanos y el defensor del puebl

Detrás de la oscuridad, viene la luz (experiencias vividas por una enfermera)

Este relato describe una situación en la que la enfermera encargada de los cuidados a los demás se transforma de repente en una persona que tiene que ser cuidada de un grave problema de salud. Este súbito cambio de rol experimentado por esta enfermera constituye una fuente para que los profesionales sean capaces de ponerse en la piel de las personas que cuidan porque en cualquier momento pueden ser ellos los que tengan que ser cuidados.This story describes a situation in which the nurse in charge of care to others is suddenly transformed into a person who has to be careful of a serious health problem. This sudden change of role experienced by this nurse is a source for professionals to be able to step into the shoes of people who care porque en any time may be the ones that have to be maintained.Esta história descreve uma situação em que a enfermeira encarregada de cuidar do outro é subitamente transformado em uma pessoa que tem que ter cuidado com um grave problema de saúde. Esta súbita mudança de papel vivido por esta enfermeira é uma fonte de profissionais para ser capaz de entrar na pele de pessoas que se preocupam porque..en qualquer momento podem ser os que têm de ser mantidos

Factors associated with long COVID syndrome in a Colombian cohort

9 páginasAfter acute phase of SARS-CoV-2 infection, some patients persist with clinical symptoms, a phenomenon known as Long COVID syndrome. It is necessary to understand the factors associated with the persistence of these symptoms to develop individualized preventive approaches and effectively address this challenge.Maestría en EpidemiologíaMagíster en Epidemiologí

El análisis sociológico del consumo: una revisión histórica de sus desarrollos teóricos.

[Abstract] The article makes a route by the main currents and theoretical contributions in the sociological analysis of the consumption. From Veblen to the post... modern consumption, the Sociology of Comsumption is outstanding the social and cultural aspects that surround a so complex and relevant phenomenon in our capi... talist societies as it is the consumption. The author warns of the suitability to do this route considering the influence of the advances in social theory as well as the trans... formations of the capitalist society on the exposed expositions. In this sense the text is crossed by diverse controversies that have centered the interest of the sociological discipline like is the more or less active character of the social actors or the paper of the social classes in the societies outposts, and that makes comprehensible the slid... ing that the theoretical interpretations of consumption have shown from a concep... tion of consumption as mere marker or expression of the economic position to the idea of consumption as a process by means of which the personal and social identi... ty is formed.[Resumen] El artículo realiza un recorrido por las principales corrientes y aportaciones teóricas en el análisis sociológico del consumo. Desde el consumo ostentoso de Veblen hasta el consumo postmoderno, la Sociología del Consumo ha destacado los aspectos sociales y culturales que rodean un fenómeno tan complejo y relevante en nuestras sociedades capitalistas como éste. La autora advierte de la idoneidad de hacer este recorrido teniendo en cuenta la influencia de los avances en teoría social así como las transformaciones de la sociedad capitalista sobre los planteamientos expuestos. En este sentido el texto se ve atravesado por diversas controversias que han centrado el interés de la disciplina sociológica como es el carácter más o menos activo de los actores sociales o el papel de las clases sociales en las sociedades avan... zadas, y que hacen comprensible el deslizamiento que las interpretaciones teóricas del consumo han mostrado desde una concepción del consumo como mero marca... dor o expresión de la posición económica a la idea del consumo como un proceso a través del cual se configura la identidad personal y social

Innovación en educación física a través de las "otras" materias instrumentales: música, gesto y artes plásticas. Propuesta transdisciplinar de fomento de la cultura: "el caracol-la espiral"

La propuesta de innovación docente que presentamos se ha experimentado con los estudiantes de la especialidad de Educación Física en Magisterio. La idea globalizadora parte de un elemento físico (el caracol) y de un icono (la espiral), se apoya en un artista andaluz universal, Pablo Ruiz Picasso, y necesita recabar información sonora y visual. Con todo ello, la acción consiste en la elaboración por parte de los estudiantes de pósters que recojan la información y permitan hacer demostraciones prácticas a través del movimiento. Desde los ámbitos transdisciplinar y ecoformativo, ayudaremos a comprender el arte, la música, la expresión corporal, el movimiento y la actividad física. En definitiva, se trata de llegar a la cultura por medio de las materias que conforman el Departamento, en un proceso creativo, interdisciplinar e innovador que abarque también las competencias básicas.The proposal of educational innovation that we display in this contribution has been applied to university students of Physical Education (EF). The global idea departs from a physical element (the snail), an icon (the spiral) and an Andalusian and universal artist, Pablo Ruiz Picasso, to successfully obtain musical and artistic information. The action consists on the elaboration by the students of posters which collect information and allow realize practical demonstrations through movement. “The snail-the spiral” is an image that opens to the multisensory field and aids to understand art, music, corporal expression, movement and physical activity, from transdicisciplinary and ecopedagogical scopes. The aim is to obtain a cultural approach through the subjects which conform the Department, by means of a creative, interdisciplinary and innovative process which also includes the basic competencies

Seasonal changes in antioxidative/oxidative profile of mining and non-mining populations of Syrian beancaper as determined by soil conditions

Soil pollution by heavy metals/metalloids (HMMs) is a problem worldwide. To prevent dispersion of contaminated particles by erosion, the maintenance of a vegetative cover is needed. Successful plant establishment in multi-polluted soils can be hampered not only by HMM toxicities, but also by soil nutrient deficiencies and the co-occurrence of abiotic stresses. Some plant species are able to thrive under these multi-stress scenarios often linked to marked fluctuations in environmental factors. This study aimed to investigate the metabolic adjustments involved in Zygophyllum fabago acclimative responses to conditions prevailing in HMM-enriched mine-tailings piles, during Mediterranean spring and summer. To this end, fully expanded leaves, and rhizosphere soil, of three contrasting mining and non-mining populations of Z. fabago grown spontaneously in south-eastern Spain were sampled in two consecutive years. Approximately 50 biochemical, physiological and edaphic parameters were examined, including leaf redox components, primary and secondary metabolites, endogenous levels of salicylic acid, and physicochemical properties of soil (fertility parameters and total concentration of HMMs). Multivariate data analysis showed a clear distinction in antioxidative/oxidative profiles between and within the populations studied. Levels of chlorophylls, proteins and proline characterized control plants whereas antioxidant capacity and C- and S-based antioxidant compounds were biomarkers of mining plants. Seasonal variations were characterized by higher levels of alkaloids and PAL and soluble peroxidase activities in summer, and by soluble sugars and hydroxycinnamic acids in spring irrespective of the population considered. Although the antioxidant systems are subjected to seasonal variations, the way and the intensity with which every population changes its antioxidative/oxidative profile seem to be determined by soil conditions. In short, Z. fabago displays a high physiological plasticity that allow it to successfully shift its metabolism to withstand the multiple stresses that plants must cope with in mine tailings piles under Mediterranean climatic conditions.This work was supported by the Ministerio de Ciencia e Innovación [grant number CTM2011-23958]; Ministerio de Ciencia y Tecnología [grant number CGL2006-11569]; and Fundación Séneca [grant number FB/23/FS/02]. AL-O holds a grant from the Ministerio de Educación Cultura y Deporte [grant number AP2012-2559]. Part of this work was carried out at the Instituto de Biotecnología Vegetal, UPCT