Assessment of the eutectic thorugh and properties of a multiphase alloy in the NiAl-Cr-W system

Mención Internacional en el título de doctorLos compuestos intermetálicos ordenados han ganado atención en la comunidad científica durante las últimas décadas, debido a la interesante combinación de propiedades que presentan, siendo candidatos perfectos como materiales estructurales para aplicaciones de alta temperatura. Especialmente prometedoras son las propiedades de los aluminuros metálicos, entre las que se cuentan: un alto punto de fusión, alta conductividad térmica, alto límite elástico, baja densidad, y una excelente resistencia a la oxidación, debido a la formación de alúmina en la superficie. De entre ellos, el NiAl fue señalado como el candidato más prometedor para mayores temperaturas. Sin embargo, su baja ductilidad y tenacidad a fractura a temperatura ambiente, así como su baja resistencia y resistencia a fluencia a alta temperatura, hicieron que se redujese el interés por este material. A pesar de ello, se continuó investigando para superar estas desventajas, y los materiales compuestos in situ de eutécticos de NiAl, como son NiAl-Cr, NiAl-W, etc., han mostrado los mejores resultados. Aún así, las aleaciones eutécticas binarias tienen una limitación intrínseca, ya que la composición está fijada, y por ello también lo está la fracción volumétrica de la fase reforzante. En este trabajo se exploró una manera de abordar esta limitación. A través de la introducción de un elemento específico, es posible obtener un material compuesto in situ eutéctico de NiAl, en el que la fracción volumétrica de la fase reforzante sea ajustable. Esto se debe a que los eutécticos binarios forman líneas eutécticas en el diagrama de fases ternario, en las que la composición y la fracción volumétrica de la fase reforzante es variable. Este planteamiento fue aplicado al sistema NiAl-Cr-W. Debido a la gran diferecia entre los elementos de dicho sistema, el procesado de las aleaciones tuvo que ser perfeccionado. Se investigó la producción y uso de prealeaciones como ruta de procesado, lo cual derivó en resultados satisfactorios tanto en colada como en solidificación direccional. Mediante la medida de la composición del microconstituyente eutéctico en las aleaciones, se evaluó de manera preliminar la línea eutéctica en el diagrama de fases pseudo-ternario. Los resultados indicaron la existencia de una línea eutéctica discontinua, de la que se determinaron dos secciones en las regiones de alto y bajo contenido en Cr, y además se confirmó la existencia de un hueco entre ambas. Dicha evaluación fue mejorada por medio de un análisis exhaustivo del recorrido de las aleaciones durante la solidificación, principalmente mediante una mejor caracterización de su microestructura y la composición de sus fases. Además se utilizaron cálculos asistidos por ordenador de forma complementaria. Este estudio demostró que la línea eutéctica discontinua se debe a la existencia de otra línea de reacción en el sistema pseudo-ternario, que no había sido detectada hasta el momento. Esta línea de reacción se forma a causa de la región de inmiscibilidad que presenta el diagrama de fases de Cr-W desde temperaturas muy altas, y se extiende a través del diagrama pseudo-ternario como una reacción peritéctica. La interacción de ambas secciones de la línea eutéctica con esta nueva línea de reacción, es la razón por la cual existe la discontinuidad, formando un punto de equilibrio de cuatro fases de clase II, también llamado reacción tipo U, en el sistema pseudo-ternario. Además, se estudió el efecto de la naturaleza cuaternaria del sistema, respecto al enfoque pseudo-ternario seguido en la investigación, confirmando la validez del método. Adicionalmente se estudió el comportamiento mecánico a alta temperatura de la aleación multifásica NiAl-20Cr-4.5W (en porcentage atómico), y los resultados indicaron que la aleación presenta unas propiedades a alta temperatura menores, pero comparables, con aquellas de las aleaciones de NiAl más avanzadas desarrolladas hasta el momento. Estos resultados animan a continuar la investigación de éste y otros sistemas de una manera similar, ya que la aleación estudiada no posee una microestructura optimizada como la de las avanzadas.Ordered intermetallic compounds have gained attention over the past decades in the research community, due to their interesting combination of properties, which make them attractive candidates as potential structural materials for high temperature applications. Especially promising are the properties of metal-aluminides, which include high melting point, high thermal conductivity, high yield strength, low density, and excellent oxidation resistance due to the formation of alumina scales. Among them, NiAl was initially identified as the most promising candidate for higher temperatures. However, its low ductility and fracture toughness at room temperature, as well as its low strength and creep resistance at high temperatures, reduced the interest in this material. In spite of this, further research has been carried out in order to improve the drawbacks, and in situ composites of NiAl-based eutectic alloys like NiAl-Cr, NiAl-W, and so on, have brought the best results. All the same, binary eutectic alloys present an inherent limitation, as the composition is fixed, and thus, the volume fraction of reinforcement phase is fixed as well. In this work, an approach to overcome this limitation is explored. By the introduction of another specific element, it is possible to obtain a NiAl-based fully-eutectic in situ composite with a tuneable reinforcement volume fraction. This is because fixed-composition binary eutectics form eutectic troughs in the ternary phase diagram, in which the composition and volume fraction of the reinforcement phase is variable. This approach was studied in the NiAl-Cr-W system. Due to the large differences between the elements in the system, the processing of the alloys had to be improved. A prealloy production route was investigated, which yielded satisfactory results in casting and directional solidification. Through the measurement of the composition of the eutectic constituent present in the alloys, the eutectic trough in the pseudo-ternary phase diagram was initially assessed. The results showed a discontinuous eutectic trough, in which two sections in the Cr-rich and Cr-lean regions were assessed, and a gap between both was acknowledged. The assessment was enhanced by thorough analysis of the path followed during solidification of the alloys, mainly by further characterization of their microstructure and phases composition. Complementary computer-aided calculations were also used. The study revealed that the discontinuous eutectic trough occurs due to the existence of a non-reported reaction line in the pseudo-ternary system. This line forms owing to the miscibility gap present in Cr-W phase diagram, which extends up to high temperatures in the pseudo-ternary diagram, and develops as a peritectic reaction. The interaction between the eutectic trough sections and this new reaction line is the cause of the discontinuity, forming a point of class II four-phase equilibria, or U-type reaction, in the pseudo-ternary system. Furthermore, the effect of the quaternary nature of the system in the pseudo-ternary approach used in the investigation was studied, and the method validity was confirmed. Additionally, the high temperature behavior of multiphase NiAl-20Cr-4.5W (in at.%) alloy was studied, and the results revealed that the alloy exhibits high-temperature properties which are inferior, but comparable, to those of the most advanced NiAl-based alloys developed so far. These results are encouraging for further research in this and other systems with a similar approach, as the tested alloy does not possess an optimized microstructure like that of advanced alloys.Programa Oficial de Doctorado en Ciencia e Ingeniería de MaterialesPresidente: Frank Stein.- Secretario: Mónica Campos Gómez.- Vocal: Easo Georg

Secuenciación de genomas de SARS-CoV-2: herramienta clave en esta pandemia

La pandemia causada por el nuevo coronavirus SARS-CoV-2 no sólo está afectando de manera muy sensible al modo de vida de miles de millones de personas, sino que, a la vez de reto científico y médico, está suponiendo un nuevo paradigma en la detección, caracterización y seguimiento epidemiológico del agente causal. Y sin lugar a duda la secuenciación completa del genoma de SARS-CoV-2 a partir de muestras clínicas es el estandarte de este nuevo paradigm

Emergence of Progressive Mutations in SARS-CoV-2 From a Hematologic Patient With Prolonged Viral Replication

We documented a hematologic patient with prolonged SARS-CoV-2 viral replication in whom emergence of viral mutations was documented after the consecutive use of antivirals and convalescent plasma. The virus detected in the last of 12 clinical samples (day 237) had accumulated 22 changes in amino acids and 29 in nucleotides. Some of these changes, such as the E484Q, were mutations of concern as defined by WHO. This finding represents an enormous epidemiological threat and poses a major clinical challenge. Combined antiviral strategies, as well as specific strategies related to the diagnostic approach of prolonged infections for this specific population, may be needed.This work has been financed by funds for research ad hoc COVID-19 from patronage provided by citizens and organizations to Hospital Clínic de Barcelona-Fundació Clínic per a la Recerca Biomèdica. This work received support from FONDO-COVID19 (ISCIII Grant number: COV20-00679), Instituto de Salud Carlos III (PI21/01640) and by European Region (ERDF, “A way to make Europe”). PP-A [JR20/00012 and PI21/00498], NG-P [FI19/00133], have also received research grants from the Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III. The funders had neither a specific role in study design or collection of data, nor in writing of the paper or decision to submit.S

Genomic characterisation of respiratory syncytial virus: a novel system for whole genome sequencing and full-length G and F gene sequences

To advance our understanding of respiratory syncytial virus (RSV) impact through genomic surveillance, we describe two PCR-based sequencing systems, (i) RSVAB-WGS for generic whole-genome sequencing and (ii) RSVAB-GF, which targets major viral antigens, G and F, and is used as a complement for challenging cases with low viral load. These methods monitor RSV genetic diversity to inform molecular epidemiology, vaccine effectiveness and treatment strategies, contributing also to the standardisation of surveillance in a new era of vaccines.This research was partially funded by Instituto de Salud Carlos III through the Project PI18/00167, PI21CIII/00019 (MPY 439-21) and PI21/00377, and partially by UNESPA donation- “COVIDSEQUNESPA” (grant number MPY 226/22). Also, funding was received from grant MSD MISP: IISP 60255.S

ARIA 2016: Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

Abstract The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma and rhinitis and (3) to develop guidelines with all stakeholders that could be used globally for all countries and populations. ARIA—disseminated and implemented in over 70 countries globally—is now focusing on the implementation of emerging technologies for individualized and predictive medicine. MASK [MACVIA (Contre les Maladies Chroniques pour un Vieillissement Actif)-ARIA Sentinel NetworK] uses mobile technology to develop care pathways for the management of rhinitis and asthma by a multi-disciplinary group and by patients themselves. An app (Android and iOS) is available in 20 countries and 15 languages. It uses a visual analogue scale to assess symptom control and work productivity as well as a clinical decision support system. It is associated with an inter-operable tablet for physicians and other health care professionals. The scaling up strategy uses the recommendations of the European Innovation Partnership on Active and Healthy Ageing. The aim of the novel ARIA approach is to provide an active and healthy life to rhinitis sufferers, whatever their age, sex or socio-economic status, in order to reduce health and social inequalities incurred by the disease

ARIA 2016:Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma and rhinitis and (3) to develop guidelines with all stakeholders that could be used globally for all countries and populations. ARIA-disseminated and implemented in over 70 countries globally-is now focusing on the implementation of emerging technologies for individualized and predictive medicine. MASK [MACVIA (Contre les Maladies Chroniques pour un Vieillissement Actif)-ARIA Sentinel NetworK] uses mobile technology to develop care pathways for the management of rhinitis and asthma by a multi-disciplinary group and by patients themselves. An app (Android and iOS) is available in 20 countries and 15 languages. It uses a visual analogue scale to assess symptom control and work productivity as well as a clinical decision support system. It is associated with an inter-operable tablet for physicians and other health care professionals. The scaling up strategy uses the recommendations of the European Innovation Partnership on Active and Healthy Ageing. The aim of the novel ARIA approach is to provide an active and healthy life to rhinitis sufferers, whatever their age, sex or socio-economic status, in order to reduce health and social inequalities incurred by the disease

ARIA 2016 : Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma and rhinitis and (3) to develop guidelines with all stakeholders that could be used globally for all countries and populations. ARIA-disseminated and implemented in over 70 countries globally-is now focusing on the implementation of emerging technologies for individualized and predictive medicine. MASK [MACVIA (Contre les Maladies Chroniques pour un Vieillissement Actif)-ARIA Sentinel NetworK] uses mobile technology to develop care pathways for the management of rhinitis and asthma by a multi-disciplinary group and by patients themselves. An app (Android and iOS) is available in 20 countries and 15 languages. It uses a visual analogue scale to assess symptom control and work productivity as well as a clinical decision support system. It is associated with an inter-operable tablet for physicians and other health care professionals. The scaling up strategy uses the recommendations of the European Innovation Partnership on Active and Healthy Ageing. The aim of the novel ARIA approach is to provide an active and healthy life to rhinitis sufferers, whatever their age, sex or socio-economic status, in order to reduce health and social inequalities incurred by the disease.Peer reviewe

ARIA 2016: Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma a

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three genomic nomenclature systems to all sequence data from the World Health Organization European Region available until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation, compare the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2

Positioning the principles of precision medicine in care pathways for allergic rhinitis and chronic rhinosinusitis - A EUFOREA-ARIA-EPOS-AIRWAYS ICP statement.

Precision medicine (PM) is increasingly recognized as the way forward for optimizing patient care. Introduced in the field of oncology, it is now considered of major interest in other medical domains like allergy and chronic airway diseases, which face an urgent need to improve the level of disease control, enhance patient satisfaction and increase effectiveness of preventive interventions. The combination of personalized care, prediction of treatment success, prevention of disease and patient participation in the elaboration of the treatment plan is expected to substantially improve the therapeutic approach for individuals suffering from chronic disabling conditions. Given the emerging data on the impact of patient stratification on treatment outcomes, European and American regulatory bodies support the principles of PM and its potential advantage over current treatment strategies. The aim of the current document was to propose a consensus on the position and gradual implementation of the principles of PM within existing adult treatment algorithms for allergic rhinitis (AR) and chronic rhinosinusitis (CRS). At the time of diagnosis, prediction of success of the initiated treatment and patient participation in the decision of the treatment plan can be implemented. The second-level approach ideally involves strategies to prevent progression of disease, in addition to prediction of success of therapy, and patient participation in the long-term therapeutic strategy. Endotype-driven treatment is part of a personalized approach and should be positioned at the tertiary level of care, given the efforts needed for its implementation and the high cost of molecular diagnosis and biological treatment