Thermal Healing of Realistic Flaws in Glass

For any given environmental conditions the tensile strength of glass is a function of the geometry of the critical flaw and the residual stresses in the vicinity of the flaw. The strength of heat treated glass is conventionally considered to be equal to the sum total of the residual stress and the extrinsic strength of annealed glass. Recent experiments Suggest that there is an additional contribution to strength due to crack healing. In order to quantify it, uniaxial and equibiaxial strength tests on both as-received and carefully annealed glass specimens were performed for different edge geometries and edge finishes. The results show that strength recovery due to healing is significant and this strength gain appears to correlate with the quality of the edge finish. Possible explanations of this phenomenon are provided. Independently of healing effects, it was also found that the edge quality has a marginal effect on the mean strength, but has a significant positive effect at low fractile values often used in design applications.The contribution of Chris Cavanagh to part of the experimental testing, Trend Marine Ltd and Engineering and Physical Sciences Research Council (EPSRC) is gratefully acknowledge

Collaboration between a human group and artificial intelligence can improve prediction of multiple sclerosis course. A proof-of-principle study

Background: Multiple sclerosis has an extremely variable natural course. In most patients, disease starts with a relapsing-remitting (RR) phase, which proceeds to a secondary progressive (SP) form. The duration of the RR phase is hard to predict, and to date predictions on the rate of disease progression remain suboptimal. This limits the opportunity to tailor therapy on an individual patient's prognosis, in spite of the choice of several therapeutic options. Approaches to improve clinical decisions, such as collective intelligence of human groups and machine learning algorithms are widely investigated. Methods: Medical students and a machine learning algorithm predicted the course of disease on the basis of randomly chosen clinical records of patients that attended at the Multiple Sclerosis service of Sant'Andrea hospital in Rome. Results: A significant improvement of predictive ability was obtained when predictions were combined with a weight that depends on the consistence of human (or algorithm) forecasts on a given clinical record. Conclusions: In this work we present proof-of-principle that human-machine hybrid predictions yield better prognoses than machine learning algorithms or groups of humans alone. To strengthen this preliminary result, we propose a crowdsourcing initiative to collect prognoses by physicians on an expanded set of patients

Electrospun materials for energy applications: from Lithium-ion batteries to electrets

The aim of this work is focused on the application of electrospinning technology, an innovative manufacturing technique to design nanostructured polymers, for energy storage, energy harvesting and sensor applications. These nanostructures are suitable to increase specific performances of components: from the reduction of internal resistance of Lithium-ion batteries to the increase of specific electrical response of materials for energy harvesting. The increase of specific power of Lithium-ion batteries represents one of the key factors for the development of competitive storage systems for automotive and power grid. Indeed, electrochemical performances at high currents significantly decay, strongly limiting the competitiveness on the market beyond portable applications. Furthermore, recovery of dissipated energy will be one of the most promising challenges for the establishment of green technologies and for the reduction in power consumption. Finally, health monitoring and/or impact sensors could represent suitable technologies for the growth of smart materials. This Ph.D. thesis covers the study of PVdF-based polymers to develop enhanced materials for Lithium-ion batteries and energy harvesters.Questa tesi verte sull’applicazione della tecnica dell’electrospinning per realizzare polimeri nanostrutturati da impiegare nel campo dell’accumulo energetico, del recupero dell’energia dissipata e della sensoristica. Queste nanostrutture possono incrementare la risposta specifica dei componenti: dalla riduzione della resistenza interna delle batterie Litio-ione all’incremento della risposta elettrica specifica di materiali per il recupero dell’energia. L’incremento della potenza specifica delle batterie Litio-ione rappresenta una delle maggiori sfide per lo sviluppo di sistemi di taglia elevata, per applicazioni nel settore “automotive” e per l’accumulo in rete. Infatti le prestazioni elettrochimiche ad elevate correnti decadono significativamente, limitando fortemente la competitività di tali accumulatori al di fuori delle applicazioni portatili. Inoltre il recupero dell’energia dissipata rappresenta una delle strategie più promettenti per lo sviluppo di tecnologie a basso impatto ambientale e per la riduzione dei consumi energetici. Infine sensori di impatto o sistemi per l’”health monitoring” realizzati mediante tali nanostrutture possono contribuire sensibilmente allo sviluppo di “smart materials”. Questa tesi di Dottorato concerne dunque lo studio di polimeri fluorurati a base PVdF per lo sviluppo di materiali innovativi per batterie Litio-ione e per dispositivi per il recupero dell’energia

Effect of oxide nanoparticles on thermal and mechanical properties of electrospun separators for lithium-ion batteries

This study reports the fabrication and characterization of poly(ethylene oxide) (PEO) and poly(vinylidenefluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) nanofibrous separators for lithium-ion batteries loaded with different amounts of fumed-silica and tin oxide nanoparticles. Membrane morphological characterization (SEM, TEM) showed the presence of good-quality nanofibres containing nanoparticles. Thermal degradation and membrane mechanical properties were also investigated, and a remarkable effect of nanoparticle addition on membrane mechanical properties was found. In particular, PEO membranes were strengthened by the addition of metal oxide, whereas PVDF-CTFE membranes acquired ductility

Menadione-induced oxidative stress re-shapes the oxylipin profile of Aspergillus flavus and its lifestyle

Aspergillus flavus is an efficient producer of mycotoxins, particularly aflatoxin B1, probably the most hepatocarcinogenic naturally-occurring compound. Although the inducing agents of toxin synthesis are not unanimously identified, there is evidence that oxidative stress is one of the main actors in play. In our study, we use menadione, a quinone extensively implemented in studies on ROS response in animal cells, for causing stress to A. flavus. For uncovering the molecular determinants that drive A. flavus in challenging oxidative stress conditions, we have evaluated a wide spectrum of several different parameters, ranging from metabolic (ROS and oxylipin profile) to transcriptional analysis (RNA-seq). There emerges a scenario in which A. flavus activates several metabolic processes under oxidative stress conditions for limiting the ROS-associated detrimental effects, as well as for triggering adaptive and escape strategies

Outcome of acute type A aortic dissection: single-center experience from 1998 to 2007

Introduction. Acute aortic dissection (AAD) is a serious disease of the aorta with high mortality and morbidity, which requires emergency surgical treatment in order to close the site of the dissection and direct blood flow into the true lumen. Improvements in surgical technique have led to better management of patients with reduced operative mortality, although it still remains high. The aim of this study is to evaluate early and late outcomes of the surgical treatment of acute type A aortic dissection at the hospital of Lecce between 1998 and 2007. We also aim to establish a correlation between these outcomes and pre-operative conditions, surgical procedures and location of the site of the tear. Methods. From 1998 to 2007, 100 patients (69 males and 31 females, average age 62.2 ? 12.3 years, range 22-85 years) underwent surgery for acute AAD at the center. Surgical techniques included replacement of the ascending aorta (Asc Ao) with or without valve replacement (including five patients who underwent the Bentall/De Bono procedure) and replacement of the Asc Ao with or without arch or hemiarch replacement. Results. In-hospital mortality was 22%, with different results between surgery for replacement of the aorta and for aorta with valve replacement (respectively, 16% and 23%). Different mortality rates were found between the distal surgical treatments, with rates of 20.8% and 18.2% respectively between replacements of the Asc Ao and of Asc Ao with arch/hemiarch, although they were not statistically significant. A different mortality rate that was subject to the patient\u27s preoperative condition has also been found (33.3% of mortality in patients in unstable or highrisk condition vs 13.8% in patients in stable condition). The peak reached 43.5% mortality in patients taken to the operating room while in shock or cardiac tamponade. The location of the site of the tear is another factor that distinguishes mortality rates, which are 17.8% if localized at the proximal ascending aorta and 22.2% in the aortic arch. Assessment of the outcome (10 years after surgery), has shown that four patients died several years later but for reasons unrelated to the surgery. Conclusions. The surgery of dissection is still an intervention with a relatively high in-hospital mortality risk, and whose outcome, which has been steady in the last 20 years, can be predicted according to the preoperative condition of the patient. This underlines the need to reduce the time of diagnosis indicating immediate surgical treatment