161,011 research outputs found
Arrhythmogenic Cardiomyopathy: Mechanotransduction Going Wrong
No full textArrhythmogenic cardiomyopathy (AC) is a genetic disorder characterized by
high risk of life-threatening ventricular arrhythmias, sudden cardiac death,
and progressive heart failure. Currently, there is evidence that AC includes
a spectrum of cardiomyopathy phenotypes, ranging from the classical form of arrhythmogenic
right ventricular cardiomyopathy (ARVC) to more recently identified
forms of arrhythmogenic left ventricular cardiomyopathy
Effect of LaNbO4 addition on the mechanical properties of ceria-tetragonal zirconia polycrystal matrices
No full textThe formation of needle-like grains of LaNbO4 in CeO2-stabilized tetragonal zirconia (Ce-TZP) matrices was studied using powders produced by different methods. The amount as well as the aspect ratio of the elongated grains is a function of the sintering temperature and the way the powders have been produced. The formation of these needles is triggered by the presence of silica in the starting powders and, therefore, by the occurrence of a liquid phase. During sintering, also diffusion of Ce in LaNbO4 occurs. The matrices are therefore depleted in stabiliser's content affecting their transformability. Because of the elongated nature of the grains enhanced crack wake bridging occur, this bridging should be also accounted for the observed increase of strength and toughness. (C) 1998 Elsevier Science Limited. All rights reserved
La vulnerabilità della “Green economy”
No full textThe transition to a low-carbon economy is accelerating also thanks to the 2016 Paris Agreement and the Sustainable Development Goals, adopted by the United Nations General Assembly in 2015. The conditions are therefore in place for reducing by 2050 the production of energy using coal or natural gas to a minimum or to zero. Unfortunately, however, the new “clean” or “green” energy technologies depend very much on the availability and cost of certain elements called rare earths. The availability of some of these materials is at risk due to their inaccessibility, their vulnerability to supply interruptions and the lack of suitable substitutes. This work briefly examines the industrial demand for these elements, some of their applications and the geological and geopolitical difficulties for their supply.
La transizione verso un’economia a basse emissioni di Carbonio sta accelerando, in parte supportata dall’accordo di Parigi del 2016 e dagli obiettivi di sviluppo sostenibile, adottati dall'Assemblea generale delle Nazioni Unite nel 2015. Ci sono quindi le condizioni affinché sia possibile raggiungere entro il 2050 una situazione in cui la produzione di energia, usando carbone o gas naturale, sarà ridotta al minimo o azzerata. Purtroppo però le nuove tecnologie energetiche “pulite” o “verdi” dipendono per ora moltissimo dalla disponibilità e dal costo di certi elementi chiamati Terre rare. La disponibilità di alcuni di questi materiali è a rischio a causa della loro localizzazione, della loro vulnerabilità a interruzioni di fornitura e alla mancanza di idonei sostituti. Questo lavoro esamina brevemente la richiesta industriale di questi elementi, alcune loro applicazioni e le difficoltà geologiche e geopolitiche per il loro approvvigionamento
Current understanding of the role of cytoskeletal cross-linkers in the onset and development of cardiomyopathies
No full textCardiomyopathies affect individuals worldwide, without regard to age, sex and ethnicity and are associated with significant morbidity and mortality. Inherited cardiomyopathies account for a relevant part of these conditions. Although progresses have been made over the years, early diagnosis and curative therapies are still challenging. Understanding the events occurring in normal and diseased cardiac cells is crucial, as they are important determinants of overall heart function. Besides chemical and molecular events, there are also structural and mechanical phenomena that require to be investigated. Cell structure and mechanics largely depend from the cytoskeleton, which is composed by filamentous proteins that can be cross-linked via accessory proteins. Alpha-actinin 2 (ACTN2), filamin C (FLNC) and dystrophin are three major actin cross-linkers that extensively contribute to the regulation of cell structure and mechanics. Hereby, we review the current understanding of the roles played by ACTN2, FLNC and dystrophin in the onset and progress of inherited cardiomyopathies. With our work, we aim to set the stage for new approaches to study the cardiomyopathies, which might reveal new therapeutic targets and broaden the panel of genes to be screened
Mechanical properties and microstructure of (CeO2)-stabilised ZrO2/Al2O3 composites
No full textIn this investigation a series of Al2O3-ZrO2 composites materials were prepared using unstabilised ZrO2 or different amount of either Y2O3 or CeO2 for stabilising the ZrO2 in its metastable tetragonal form. The mechanical properties (hardness, bend strength and toughness) were measured and the influence of the different micro structure obtained as well as the role of phase transformation and micro cracks has been assessed
Application of a dielectric barrier discharge plasma for heating plastic materials
No full textDielectric barrier discharge (DBD) plasma is usually referred in literature as a form of cold plasma. Many applications of DBD plasma rely on this characteristic, which allow to treat also sensitive materials, including biological tissues, to exploit a range of different effects. Atmospheric pressure plasma treatment is regularly used on polymers to enhance surface properties such as wettability and adhesion. However, in the present work, we show that DBD plasma can also be used as an alternative for heating polymeric based materials, as an initial step for further industrial processing such as thermo-forming. In particular, the efficiency of the heating process has been measured, and a novel heating mechanism has been proposed based on the experimental result
Microprobe fluorescence spectroscopy evaluation of stress fields developed along a propagating crack in an Al2O3 center dot CaO-6Al(2)O(3) ceramic composite
No full textThe fracture behavior upon stable crack propagation in bending was investigated for a ceramic matrix composite comprising 15 vol% of calcium hexaluminate (CaAl12O19 or "CA6") in an Al2O3 matrix and compared to the crack bridging stresses as measured by microprobe fluorescence spectroscopy. In addition, piezospectroscopy coefficients of -4.57 and -3.79 cm(-1) GPa(-1) were determined for the peaks located at 14488 and 14528 cm(-1), respectively, for monolithic CA6. It was concluded that the macroscopic R-curve behavior of the composite could be predicted from microscopic bridging stress data and indicated microprobe fluorescence spectroscopy to be a significant experimental tool for the investigation of fracture micromechanisms in ceramic materials
System level optimization and design of the high speed machining process using ceramic cutting tools
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