Electrolito sólido polimérico: desde las pilas de combustible hasta la electrosíntesis orgánica

En este trabajo, en primer lugar, se presenta una nueva técnica desarrollada en nuestro laboratorio para el estudio electroquímico de las capas catalíticas de las pilas de combustible en células de tres electrodos, centrándonos en el proceso de electroxidación de ácido fórmico como reacción de test. Gracias a esta técnica se han estudiado parámetros de construcción como % en peso del metal, relación Nafion / sólidos totales y recubrimiento catalítico comprobando como la adsorción irreversible de adátomos de Bi sobre Pt soportado sobre Vulcan XC-72 favorece este proceso y como puede caracterizarse la capa catalítica de una pila de combustible de ácido fórmico (DFAFC) de forma integral utilizando estudios de sistemas nanoparticulados de Pt-Pd soportados sobre Vulcan XC-72 en el seno de ésta. En segundo lugar se ha introducido el concepto de PEMER (Polymer Electrolyte Membrane Electrochemical Reactor). De esta forma, una configuración electródica propia de las pilas de combustible se utiliza en electrosíntesis orgánica. Como reacciones test se han testeado la formación de 1-feniletanol como producto mayoritario por hidrogenación electrocatalítica de la acetofenona sobre nanopartículas de Pd soportadas sobre Vulcan XC-72 como electrocatalizador y, utilizando Pb (catalizador no noble) soportado sobre Vulcan XC-72, se ha estudiado la ruptura del puente disulfuro de L-cistina y N,N-diacetil-L-cistina (NNDAC) para obtener L-cisteína y N-acetil- L-cisteína (NAC). En ambas reacciones, hidrogenación y ruptura del puente disulfuro, se han analizado tanto parámetros constructivos de la capa catalítica como parámetros de proceso tanto a escala laboratorio con el uso de un reactor comercial de 25 cm² como a escala pre-piloto con la construcción de un reactor de 100 cm².

NO adsorption on Pt (111)/Bi surfaces

The adsorption of nitric oxide (NO) on a Pt (111) surface modified with irreversible adsorbed bismuth adatoms is reported. While the voltammetric results reveal a close interaction between the two co-adsorbed compounds. In-situ infrared spectroscopy and scanning tunnelling microscopy indicate the formation of segregated adlayers. Formation of compressed Bi adlayers with modified redox properties is proposed to reconcile both results. This agrees with the observation of Bi islands in the STM images when NO is coadsorbed, not observed in the absence of NO.

Study of dopamine reactivity on platinum single crystal electrode surfaces

Dopamine is the biological molecule responsible, among other functions, of the heart beat and blood pressure regulation. Its loss, in the human body, can result in serious diseases such as Parkinson's, schizophrenia or depression. Structurally, this molecule belongs to the group of catecholamines, together with epinephrine (adrenaline) and norepinephrine (noradrenaline). The hydroquinone moiety of the molecule can be easily oxidized to quinone, rendering the electrochemical methods a convenient approach for the development of dopamine biosensors. The reactivity of similar aromatic molecules, such as catechol and hydroquinone, at well-ordered platinum surfaces, has recently been investigated in our group. In this paper, we extend these studies to the structurally related molecule dopamine. The study has been performed in neutral pH, since this is closer to the natural conditions for these molecules in biological media. Cyclic voltammetry and in situ infra-red spectroscopy have been combined to extract information about the behavior of this molecule on well-defined platinum surfaces. Dopamine appears to be electrochemically active and reveals interesting adsorption phenomena at low potentials (0.15–0.25 V vs RHE), sensitive to the single crystal orientation. The adsorption of dopamine on these surfaces is very strong, taking place at much lower potentials than the electron transfer from solution species. Specifically, the voltammetry of Pt(1 1 1) and Pt(1 0 0) in dopamine solutions shows an oxidation peak at potentials close to the onset of hydrogen evolution, which is related to the desorption of hydrogen and the adsorption of dopamine. On the other hand, adsorption on Pt(1 1 0) is irreversible and the surface appears totally blocked. Spectroscopic results indicate that dopamine is adsorbed flat on the surface. At potentials higher than 0.6 V vs RHE the three basal planes show a common redox process. The initial formation of the quinone moiety is followed by a chemical step resulting in the formation of 5,6-dihydroxyindoline quinone as final product. This oxidation process has also been investigated by vibrational spectroscopy.

Femicidio y feminicidio: un análisis de las aportaciones en clave iberoamericana

La violencia contra las mujeres es una lacra de nuestra sociedad que no se consigue erradicar. En su versión extrema e irreversible terminar con la muerte de la víctima. Desde mediados de la década de los años 70, del siglo pasado y de la mano de Diane Russell se visibilizaron los femicidios como el asesinato de una mujer por el hecho de ser mujer. Posteriormente, en los años 90, Marcela Lagarde crea el neologismo feminicidio al traducir la obra de Rusell al español. Desde entonces ambos términos han creado un espacio de conocimiento, de investigación y de acción política. El propósito de este trabajo es averiguar cómo se ha abordado el femicidio / feminicidio en las ciencias sociales en el contexto iberoamericano. Para ello se ha optado por una revisión de la literatura especializada en español y en portugués, analizando el tratamiento que reciben así como el alcance de los términos.

Enhanced removal of 8-quinolinecarboxylic acid in an activated carbon cloth by electroadsorption in aqueous solution

The effect of the electrochemical treatment (potentiostatic treatment in a filter-press electrochemical cell) on the adsorption capacity of an activated carbon cloth (ACC) was analyzed in relation with the removal of 8-quinolinecarboxylic acid pollutant from water. The adsorption capacity of an ACC is quantitatively improved in the presence of an electric field (electroadsorption process) reaching values of 96% in comparison to 55% in absence of applied potential. In addition, the cathodic treatment results in higher removal efficiencies than the anodic treatment. The enhanced adsorption capacity has been proved to be irreversible, since the removed compound remains adsorbed after switching the applied potential. The kinetics of the adsorption processes is also improved by the presence of an applied potential.

Postproduciendo (casi) nada

Postproducción es un término extraído de la industria audiovisual que alude a todas las operaciones realizadas sobre un material YA grabado o existente: música, fotografías, videos, películas, pinturas, etc. Tiene mayoritariamente un carácter entrópico, de liberación continua e irreversible de energías y nuevos productos reprogramados que revisan productos ya anteriormente reprogramados, y así de manera sucesiva hasta el infinito. ¿Podríamos imaginar una postproducción de sentido contrario? ¿Una postproducción cuyo esfuerzo tienda a cero? ¿Y si ahora preferimos seguir postproduciendo pero haciéndolo desde (casi) nada? Si extrapolamos esta otra acepción directamente hacia la práctica arquitectónica, estaríamos reivindicando una forma explícita de eficacia donde la manera de proceder (la mejor opción, la más sostenible) puede ser precisamente ‘no hacer’ o ‘hacer muy poco’. Una semejanza que nos emparentaría con Bartleby, el personaje de Herman Melville y su célebre frase: “preferiría no hacerlo”.

Lesões de extravasamento de terapêutica intravenosa com propriedades vesicantes

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Surdez induzida pelo trauma acústico

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Repercussões cardiovasculares no adulto : pós reparação de tetralogia de Fallot

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Um caso de neuropatia óptica sifilítica irreversível

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

A European response to the resource and climate challenge. CHALLENGE EUROPE Issue 22 - Challenges and new beginnings: Priorities for the EU's new leadership, September 2014

The 20th Century was characterised by growth: the world population grew by four times and its economic output grew by 40 times. At the same time, the resource use and greenhouse gas emissions increased drastically. Only within the last two decades, the worldwide extraction of resources increased by over 50%. With the expectation that the demand of resources will triple by 2050 and the demand for food, feed and fibre is projected to increase by 70%, there is no doubt that we will exceed our planet's boundaries, the safe thresholds within which humanity can continue to develop and thrive for generations to come. Crossing these boundaries could generate abrubt or irreversible environmental changes. Respecting them reduces the risk that human society and ecosystems will face irreversible damages.

Forerunners or scaremongers? Germany to abandon nuclear power. OSW Commentary No. 58, 2011-07-21

The German government’s final decision to abandon nuclear power as of 2022 has been expected for months. However, instead of calming the waters, providing solutions and answering the question ‘What next?’, it has only fanned the flames. Even the adoption of legal amendments enforcing the government’s decision by the German parliament (both the Bundestag and the Bundesrat) in late June and early July has not calmed the situation. It is more than apparent that these decisions have been made under emotional pressure: there was not enough time for accurate calculations to be made and consideration to be given to the consequences of Germany abandoning nuclear power. Chancellor Angela Merkel has so far been unable to fully convince the public that the ‘energy shift is a huge opportunity’ and that this process will be carried out on condition that ‘the supplies remain secure, the climate protected and the whole process economically efficient’1. German economic associations have warned against a politically motivated, ill-judged and irreversible abandonment of nuclear energy. They are anxious about an increase in electricity prices, the instability of supplies and environmental damage. The government believes, however, that green technologies will become a new driving force for the German economy and its main export commodity. Before that happens the industry will have to increase its use of electricity produced from fossil fuels, mainly natural gas imported from Russia. This may be exploited by Gazprom which will try to strengthen its position on the German market, and thus in the entire EU.

European climate finance: securing the best return. Bruegel Policy Brief ISSUE 2015/03, 11 September 2015

Combating climate change is perhaps the most formidable public policy challenge of our times. Unmitigated climate change will be irreversible. It will place significant costs on future generations, and expose them to unexplored risks. To mitigate climate change, global coordination is indispensable. European Union citizens consider climate change a central problem. The EU and its member states have therefore put in place signficant and costly climate mitigation policies.

Energy Signaling in the Regulation of Gene Expression during Stress

Maintenance of homeostasis is pivotal to all forms of life. In the case of plants, homeostasis is constantly threatened by the inability to escape environmental fluctuations, and therefore sensitive mechanisms must have evolved to allow rapid perception of environmental cues and concomitant modification of growth and developmental patterns for adaptation and survival. Re-establishment of homeostasis in response to environmental perturbations requires reprogramming of metabolism and gene expression to shunt energy sources from growth-related biosynthetic processes to defense, acclimation, and, ultimately, adaptation. Failure to mount an initial 'emergency' response may result in nutrient deprivation and irreversible senescence and cell death. Early signaling events largely determine the capacity of plants to orchestrate a successful adaptive response. Early events, on the other hand, are likely to be shared by different conditions through the generation of similar signals and before more specific responses are elaborated. Recent studies lend credence to this hypothesis, underpinning the importance of a shared energy signal in the transcriptional response to various types of stress. Energy deficiency is associated with most environmental perturbations due to their direct or indirect deleterious impact on photosynthesis and/or respiration. Several systems are known to have evolved for monitoring the available resources and triggering metabolic, growth, and developmental decisions accordingly. In doing so, energy-sensing systems regulate gene expression at multiple levels to allow flexibility in the diversity and the kinetics of the stress response.

Risco de queda em idosos institucionalizados

Os idosos institucionalizados apresentam risco de queda aumentado, quando comparado com os idosos não institucionalizados. A questão das quedas deve ser encarada como um grave problema de saúde pública, dadas as suas consequências e os custos irreversíveis. Assim, o estudo pretende avaliar o risco de queda em idosos institucionalizados e determinar os fatores que lhe estão associados. Trata-se de um estudo transversal descritivo-correlacional e de natureza quantitativa, que utilizou uma amostra não probabilística por conveniência composta por 136 idosos, com idades que variam entre os 65 anos e os 99 anos de idade, com uma média de idades de 85,98 anos. Os dados foram recolhidos através de um questionário, que procurava obter uma caracterização sociodemográfica, e clínica dos idosos e conhecer a história e circunstâncias das quedas. Foram utilizadas as escalas de Funcionalidade Familiar, Escala de Avaliação da Dependência nos Autocuidados e por último a POMA I (Índice de Tinetti). Os resultados revelam risco de queda bastante considerável, uma vez que se verificou que cerca de 45,6% dos idosos apresenta elevado risco de queda, 16,2% médio risco e 38,2% baixo risco. Verificamos ainda que, ser do sexo feminino e ter um baixo grau de escolaridade são fatores relacionados com o aumento do risco de queda. O mesmo apuramos relativamente ao défice cognitivo, á presença de doenças neurológicas, osteoarticulares, diminuição da acuidade visual e auditiva. Contrariamente, os idosos mais autónomos na deambulação, tomar banho e na toma da medicação são aqueles que apresentam menor risco de queda. Palavras-chave: idosos, risco de queda, institucionalização, capacidade funcional e equilíbrio.