Polymer-modified sulfonated PEEK ionomer membranes and the use of Ru3Pd6Pt as cathode catalyst for H2/O2 fuel cells

[EN] Nanocomposite membranes incorporating electrospun nanofibers of SPEEK, blended with 30 wt% PVB within a water-based matrix of SPEEK with 35 wt% PVA using water as solvent, were prepared and characterized for their application as Polymer Electrolyte Membrane Fuel Cells (PEMFCs) in H-2/O-2 operating at low temperatures. Compared with a dense bulk phase, an improvement of proton conductivity in the SPEEK-30PVB nanofiber framework was observed. The incorporation of the SPEEK-30PVB nanofibers provides mechanical improvement while the matrix phase of SPEEK-35PVA emphasizes the proton conductivity at crosslinking temperatures up to 140 degrees C. PEMFC performance tests showed promising results for the use of these novel low cost membranes. The nanocomposite membrane reached a power density which is 25% higher than that of Nafion117 membranes with MEAs constructed with Pt loading in anode and in cathode. However, when the Pt of the cathode is substituted by Ru3Pd6Pt, the power density is lower in Nafion117 MEAs than in the nanocomposite. When used commercial Pt-carbon cloth (Pt-ETEK) for the electrodes, the power density achieved is 1.4 times higher for the Nafion117 MEAs than SPEEK nano-composites. The differences observed in performance is attributed to the large polarization losses found in the composite membranes because of the interfacial phenomena associated with the use of commercial Nafion-based electrodes.This research is in the frame of Support Programme for Research and Development of the Polytechnic University of Valencia, and the Ministry of Science and for funding provided through the projects: ENE2015-69203-R. OSF thanks to CONACYT-Mexico for supporting this research with the grant 475920.Martínez-Casillas, D.; Solorza, O.; Mollá Romano, S.; Montero Reguera, ÁE.; Garcia Bernabe, A.; Compañ Moreno, V. (2019). Polymer-modified sulfonated PEEK ionomer membranes and the use of Ru3Pd6Pt as cathode catalyst for H2/O2 fuel cells. International Journal of Hydrogen Energy. 44(1):295-303. https://doi.org/10.1016/j.ijhydene.2018.09.217S29530344

Os mártires e a cristianização do território na América portuguesa, séculos XVI e XVII

O artigo investiga um grupo de atores sociais bastante relevante para viabilizar a cristianização na América portuguesa: os mártires cristãos, indivíduos muito especiais, dispostos a regar a terra com seu próprio sangue, de forma a tornar definitiva e irreversível a ocupação cristã do território. Os mártires - e principalmente a narrativa em torno deles - parecem ter sido bastante acionados para integrar a América portuguesa e seus habitantes nativos à temporalidade e territorialidade cristã. Os mártires dos séculos XVI e XVII, principalmente missionários, reeditavam os martírios do início da cristandade, que espalharam o cristianismo rumo a diversas partes do mundo na antiguidade. Dessa forma, viabilizaram a cristianização das novas fronteiras, consagrando o solo com seu sangue divino e viabilizando posteriores processos de urbanização. Além da função estratégica dos mártires para os cristãos, o texto mostra que eles também tiveram significado peculiar na interlocução com as culturas ameríndias, que tinha como um de seus principais personagens o grande guerreiro, disposto a perder seu sangue em prol de seu grupo.This paper looks into a group of social agents who played a significant role in the Christianization of Portuguese America, namely, the Christian martyrs - very special individuals who were ready to wet the land with their own blood in order to make possible a definitive and irreversible occupation of the territory by Christian settlers. The martyrs, and above all the stories told about them, seem to have been called upon to integrate Portuguese America and its native inhabitants into the temporalities and territory of Christendom. Mostly made up of missionaries, this group of 16th and 17th-century martyrs reedited the martyrdom of early Christians, who spread their creed across numerous parts of the Ancient World. They enabled the Christianization of new frontiers by consecrating the soil with their divine blood and paving the way for subsequent processes of urban development. In addition to their strategic significance for Christianity, the text also shows that their martyrdom played a specific role in the Christian settlers' interaction with Amerindian culture, whose main cults included the figure of the great warrior, ever ready to shed his own blood for his group

As capitanias hereditárias no mapa de Luís Teixeira

By means of the known map of Luís Teixeira, we analyze the evolution of the hereditary captaincies in their first 50 years. It was found that this map, despite its historical and cartographic value, has several mistakes and inconsistencies. There are errors with regard to the border lines, donatories and historical events. From the cartographic point of view, as other maps of the time, it is quite accurate in latitude but not in longitude. With regard to the dating, task made mainly by the examination of the names of the donatories, it can be said that coexist data from different times and the best explanation for this is that the author collected the most data in 1574 and then updated some information in 1586, but not all. To examine this question, we made an analysis of the evolution of these territories, whose information are dispersed. And this propitiated rectify some knowledge; by example the fact that the Bahia captaincy, in the first years, be constituted only by the city of Salvador; and about the categorization of village or cities, that is not made in the base of the greater or lesser size or importance, but by the fact of be created by the donatory or by the crown. These mistakes may perhaps be explained by the character of the map, similar to some roteiros of the time, and show in a practical way an interesting lesson, yet known theoretically: a map, no matter how beautiful and how historical it is, it can not be considered as an accurate portrayal of the reality or as a photography of the time: as any historical document, should be read carefully and with critical sense.Partindo do conhecido mapa de Luís Teixeira, apresenta-se a evolução das capitanias hereditárias nos primeiros 50 anos. Constatou-se que esse mapa, apesar de seu valor histórico e cartográfico, possui diversos equívocos e inconsistências. Há enganos com relação às linhas divisórias, aos donatários e aos acontecimentos. Do ponto de vista cartográfico, como outros mapas da época, ele é suficientemente acurado em latitude, mas pouco em longitude. Com relação à datação, feita principalmente examinando-se os nomes dos donatários, pode-se dizer que coexistem dados de diferentes épocas, e a melhor explicação é de que o autor coletou dados numa época (1574) e depois atualizou algumas informações (1586), mas não todas. Para examinar essa questão, foi feita uma breve análise das vicissitudes desses territórios, cujas informações se encontram dispersas. Isso permitiu retificar alguns conhecimentos, como, por exemplo, o fato de a Capitania da Bahia, nos primeiros anos, ser formada unicamente pela cidade de Salvador, e que a categorização em vilas ou cidades não se dá pelo maior ou menor tamanho ou importância, mas pelo fato de serem criadas ou pelo donatário ou pela coroa. Esses enganos talvez possam ser explicados pelo caráter do mapa, comparável a alguns "roteiros" da época, e podem mostrar de forma concreta uma interessante lição já conhecida teoricamente: um mapa, por mais belo e histórico que seja, e por mais louvado que tenha sido, não pode ser considerado simploriamente como um retrato fiel da realidade, uma fotografia da época: como qualquer documento histórico, deve ser lido com cuidado e sentido crítico

A ring-like accretion structure in M87 connecting its black hole and jet

The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation^{1,2}. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole^3. Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of 8.4_{-1.1}^{+0.5} Schwarzschild radii in diameter, approximately 50% larger than that seen at 1.3 mm. The outer edge at 3.5 mm is also larger than that at 1.3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects in addition to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow.Comment: 50 pages, 18 figures, 3 tables, author's version of the paper published in Natur

A ring-like accretion structure in M87 connecting its black hole and jet

The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation1,2. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole3. Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of [Formula: see text] Schwarzschild radii in diameter, approximately 50% larger than that seen at 1.3 mm. The outer edge at 3.5 mm is also larger than that at 1.3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects, in addition\ua0to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Iconografia tropical: motivos locais na arte colonial brasileira

Este artigo estuda a representação visual da natureza tropical na arte sacra do período colonial brasileiro, entre os séculos XVI e XVIII, época em que as artes visuais do país se desenvolveram no contexto do barroco introduzido pelos missionários católicos. Foi na decoração das igrejas que apareceram algumas das primeiras representações artísticas de elementos da natureza local, notadamente as frutas tropicais, produzindo novas combinações junto à tradicional ornamentação fitomórfica europeia, constituída de folhas de acantos e vinhas. Após um levantamento das ocorrências dessas manifestações da temática local na decoração dos templos presentes nas regiões nordeste e sudeste do país, este trabalho aborda, nos textos dos viajantes e missionários produzidos no período, as interpretações cristãs da natureza tropical que permitiram o aproveitamento desses motivos como parte da estratégia de pregação e conversão católica por meio da alegorização moral e religiosa da natureza do Novo Mundo.This paper studies the visual representation of local nature in the sacred art developed during the colonial period of Brazilian history. In this period, between the XVIth and the XVIIIth centuries, the visual arts in the country evolved in the context of the Baroque introduced by Catholic missionaries. It was in the decoration of the churches in which the first representations of aspects of local nature, mostly the tropical fruits, appeared in Brazilian visual arts, producing new combinations together with the traditional European phytomorphic ornamentation of acanthus leaves and grapes. This research draws upon texts written by travellers and missionaries during the period to demonstrate how the Europeans interpreted and represented tropical nature and used these representations as part of the Catholic preaching strategy by means of moral and religious allegorization of the New World nature