Superior pinning properties in nano-engineered YBa2Cu3O7-δ

Large electrical current transport in the absence of energy losses is the key factor in commercial applications of high temperature superconductors. This thesis demonstrates an easy and inexpensive bottom-up technique to produce self assembled nanorods, segmented nanorods as well as nanoparticles in YBa2Cu3O7-δ thin films grown by pulsed laser deposition. The structural and morphological characteristic of the pinning landscapes produced are investigated and correlated to their effects on the superconducting properties of the thin films. In particular two pinning landscapes are investigated: Ba2YNbO6 nanorods are grown in YBa2Cu3O7-δ thin films using a Ba2YNbO6 doped YBa2Cu3O7-δ pulsed laser deposition targets and Ba2(Y/Gd)(Nb/Ta)O6 segmented nanorods together with (Y/Gd)2O3 nanoparticles are grown in (Y/Gd)Ba2Cu3O7-δ thin films using a Ba2YNbO6 + Gd3TaO7 doped YBa2Cu3O7-δ pulsed laser deposition targets. The Ba2YNbO6 + YBa2Cu3O7-δ is deeply characterised and the effects of the deposition parameters are analysed. Ba2YNbO6 is demonstrated to be an interesting novel pinning addition capable to increase the critical current and to reduce the YBa2Cu3O7-δ critical currents angular dependencies anisotropy. The Ba2YNbO6 + Gd3TaO7 + YBa2Cu3O7-δ is found to produce a new complex pinning landscape extremely effective. At high fields the synergetic combination of the different defects typology is shown to generate an interesting new feature in the critical current angular dependencies. Chapter 1 is an introduction to superconductivity, the fundamentals of the field are briefly presented. In chapter 2 the discussion in focused on pinning in high temperature superconductors. Cuprates and in particular YBa2Cu3O7-δ are presented. The pinning phenomenon and the practical pinning engineering in thin films is also discussed in this chapter. Chapter 3 describes the thin films preparation methods and the characterisation techniques used in the research work. Chapter 4 and 5 are focused on the Ba2YNbO6 doped YBa2Cu3O7-δ thin films. Chapter 4 is an introduction to Ba2YNbO6 doped YBa2Cu3O7-δ, the preliminary results obtained on Ba2YNbO6 doped YBa2Cu3O7-δ thin films are shown in this chapter. The crystalline structure, the morphology and the superconducting properties of thin films deposited adopting different deposition parameters are analysed and discussed in chapter 5. In chapter 6 the new complex pinning landscape of Ba2(Y/Gd)(Nb/Ta)O6 and (Y/Gd)2O3 in (Y/Gd)Ba2Cu3O7-δ is presented. Concluding remarks on the research described in the work ends the thesis in a brief final chapter 7.The work described in this dissertetion was supported by NESPA, Nano-Engineered Superconductors for Power Application, a framework of the Marie Curie Research Training Network, funded within the EUs 6th framework program

Twinkle -- a small satellite spectroscopy mission for the next phase of exoplanet science

With a focus on off-the-shelf components, Twinkle is the first in a series of cost competitive small satellites managed and financed by Blue Skies Space Ltd. The satellite is based on a high-heritage Airbus platform that will carry a 0.45 m telescope and a spectrometer which will provide simultaneous wavelength coverage from 0.5-4.5 $\rm{\mu m}$. The spacecraft prime is Airbus Stevenage while the telescope is being developed by Airbus Toulouse and the spectrometer by ABB Canada. Scheduled to begin scientific operations in 2025, Twinkle will sit in a thermally-stable, sun-synchronous, low-Earth orbit. The mission has a designed operation lifetime of at least seven years and, during the first three years of operation, will conduct two large-scale survey programmes: one focused on Solar System objects and the other dedicated to extrasolar targets. Here we present an overview of the architecture of the mission, refinements in the design approach, and some of the key science themes of the extrasolar survey.Comment: Presented at SPIE Astronomical Telescopes & Instrumentation 202

Allergic Rhinitis and its Impact on Asthma (ARIA) Phase 4 (2018) : Change management in allergic rhinitis and asthma multimorbidity using mobile technology

Allergic Rhinitis and its Impact on Asthma (ARIA) has evolved from a guideline by using the best approach to integrated care pathways using mobile technology in patients with allergic rhinitis (AR) and asthma multimorbidity. The proposed next phase of ARIA is change management, with the aim of providing an active and healthy life to patients with rhinitis and to those with asthma multimorbidity across the lifecycle irrespective of their sex or socioeconomic status to reduce health and social inequities incurred by the disease. ARIA has followed the 8-step model of Kotter to assess and implement the effect of rhinitis on asthma multimorbidity and to propose multimorbid guidelines. A second change management strategy is proposed by ARIA Phase 4 to increase self-medication and shared decision making in rhinitis and asthma multimorbidity. An innovation of ARIA has been the development and validation of information technology evidence-based tools (Mobile Airways Sentinel Network [MASK]) that can inform patient decisions on the basis of a self-care plan proposed by the health care professional.Peer reviewe

Nickel Based Electrospun Materials with Tuned Morphology and Composition

Nickel is set to play a crucial role to substitute the less-abundant platinum in clean electrochemical energy conversion and storage devices and catalysis. The controlled design of Ni nanomaterials is essential to fine-tune their properties to match these applications. A systematic study of electrospinning and thermal post-treatment parameters has been performed to synthesize Ni materials and tune their morphology (fibers, ribbons, and sponge-like structures) and composition (metallic Ni, NiO, Ni/C, Ni3N and their combinations). The obtained Ni-based spun materials have been characterized by scanning and transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. The possibility of upscaling and the versatility of electrospinning open the way to large-scale production of Ni nanostructures, as well as bi- and multi-metal systems for widened applications

Recent developments in electrocatalyst design thrifting noble metals in fuel cells

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Multilayer Hierarchical Nanofibrillar Electrodes with Tunable Lacunarity with 2D like Pt Deposits for PEMFC

International audienceHere we present a novel approach to electrocatalyst layer design for PEMFC. Pt is conformally electrodeposited around the surface of carbon nanotubes grown on a self-standing nanofibrous electrode (NFE). We found that by combining two cost-effective and up-scalable techniques, electrospinning and electrodeposition it is possible to produce a layered electrode with tunable lacunarity and engineer the surface area distribution along the electrode thickness and in turn the Pt content distribution. It is possible to obtain an electrocatalyst with outstanding Pt exploitation and high durability while minimizing fabrication complexity. We produced hierarchical 3D electrocatalyst layers with tunable morphology that can be used directly in a membrane electrode assembly, allowing the complete exploitation of their highly porous structure, in a similar fashion to other 3D macroscopic assembly techniques

Nickel Based Electrospun Materials with Tuned Morphology and Composition

International audienceNickel is set to play a crucial role to substitute the less-abundant platinum in clean electrochemical energy conversion and storage devices and catalysis. The controlled design of Ni nanomaterials is essential to fine-tune their properties to match these applications. A systematic study of electrospinning and thermal post-treatment parameters has been performed to synthesize Ni materials and tune their morphology (fibers, ribbons, and sponge-like structures) and composition (metallic Ni, NiO, Ni/C, Ni 3 N and their combinations). The obtained Ni-based spun materials have been characterized by scanning and transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. The possibility of upscaling and the versatility of electrospinning open the way to large-scale production of Ni nanostructures, as well as bi-and multi-metal systems for widened applications

Surface-Limited Electrodeposition of Continuous Platinum Networks on Highly Ordered Pyrolytic Graphite

Continuous thin platinum nanoplatelet networks and thin films were obtained on the flat surface of highly ordered pyrolytic graphite (HOPG) by high overpotential electrodeposition. By increasing the deposition time, the morphology of the Pt deposits can be progressively tuned from isolated nanoplatelets, interconnected nanostructures, and thin large flat islands. The deposition is surface-limited and the thickness of the deposits, equivalent to 5 to 12 Pt monolayers, is not time dependent. The presence of Pt (111) facets is confirmed by High Resolution Transmission Electron Microscopy (HRTEM) and evidence for the early formation of a platinum monolayer is provided by Scanning Transmission Electron Microscopy and Energy Dispersive X-rays Spectroscopy (STEM-EDX) and X-ray Photoelectron Spectroscopy (XPS) analysis. The electroactivity towards the oxygen reduction reaction of the 2D deposits is also assessed, demonstrating their great potential in energy conversion devices where ultra-low loading of Pt via extended surfaces is a reliable strategy

Preparation of Ni@Pt core@shell conformal nanofibre oxygen reduction electrocatalysts via microwave-assisted galvanic displacement

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Highly Stable PEMFC Electrodes Based on Electrospun Antimony-Doped SnO 2

International audienceHigh durability and activity for the oxygen reduction reaction (ORR) was demonstrated for oxide-supported platinum catalysts. The supports were antimony doped SnO2 (ATO) fibres-in-tubes obtained by electrospinning and subsequent calcination. The doping with antimony instead of the already reported niobium, allowed the preparation of tin oxide with electrical conductivity similar to carbon, as well as an increased electrocatalyst loading. Platinum nanoparticles supported on electrospun ATO demonstrated higher electrochemical stability and comparable mass activity to commercial Pt/C during ex situ potential cycling. The in situ fuel cell tests also revealed an improved corrosion resistance with no noticeable degradation of the oxide based membrane electrode assembly (MEA), but a slightly lower performance compared to the MEA with carbon-supported catalysts