Strain-engineering of twist-angle in graphene/hBN superlattice devices

This is the author accepted manuscript. The final version is available on open access from American Chemical Society via the DOI in this recordThe observation of novel physical phenomena such as Hofstadter’s butterfly, topological currents, and unconventional superconductivity in graphene has been enabled by the replacement of SiO2 with hexagonal boron nitride (hBN) as a substrate and by the ability to form superlattices in graphene/hBN heterostructures. These devices are commonly made by etching the graphene into a Hall-bar shape with metal contacts. The deposition of metal electrodes, the design, and specific configuration of contacts can have profound effects on the electronic properties of the devices possibly even affecting the alignment of graphene/hBN superlattices. In this work, we probe the strain configuration of graphene on hBN in contact with two types of metal contacts, two-dimensional (2D) top-contacts and one-dimensional edge-contacts. We show that top-contacts induce strain in the graphene layer along two opposing leads, leading to a complex strain pattern across the device channel. Edge-contacts, on the contrary, do not show such strain pattern. A finite-elements modeling simulation is used to confirm that the observed strain pattern is generated by the mechanical action of the metal contacts clamped to the graphene. Thermal annealing is shown to reduce the overall doping while increasing the overall strain, indicating an increased interaction between graphene and hBN. Surprisingly, we find that the two contact configurations lead to different twist-angles in graphene/hBN superlattices, which converge to the same value after thermal annealing. This observation confirms the self-locking mechanism of graphene/hBN superlattices also in the presence of strain gradients. Our experiments may have profound implications in the development of future electronic devices based on heterostructures and provide a new mechanism to induce complex strain patterns in 2D materials.Engineering and Physical Sciences Research Council (EPSRC)Royal SocietyNewton FundLeverhulme TrustHigher Committee for Education Development in Iraq (HCED)Royal Academy of Engineerin

The Profitability of Using Pegged Currencies in Carry Trade: A Case of Saudi Riyal

This paper examines the profitability of using pegged currencies in carry trade. Conducting this exercise on Saudi riyal against six floating currencies has proven to be very rewarding especially when enhanced with forecasting methods. Carry trade is a very popular currency speculation strategy among traders, where they borrow low-interest currencies and invest in high-interest currencies. It is a strategy that takes advantage of interest rate differentials between two currencies. Such strategy should not work under uncovered interest parity (UIP), since according to UIP high interest rate currencies should depreciate against low interest rate currencies by the interest rate differential itself. But studies have shown that UIP does not stand and carry traders are profiting from it. As a result of its failure, carry traders are making returns matching the returns of the S&P 500 and outperforming it in terms of the Sharpe ratio

Novel circuit design for high-impedance and non-local electrical measurements of two-dimensional materials

This is the author accepted manuscript. The final version is available from AIP Publishing via the DOI in this recordTwo-dimensional materials offer a novel platform for the development of future quantum technologies. However, the electrical characterisation of topological insulating states, non-local resistance and bandgap tuning in atomically thin materials, can be strongly affected by spurious signals arising from the measuring electronics. Common-mode voltages, dielectric leakage in the coaxial cables and the limited input impedance of alternate-current amplifiers can mask the true nature of such high-impedance states. Here, we present an optical isolator circuit which grants access to such states by electrically decoupling the current-injection from the voltagesensing circuitry. We benchmark our apparatus against two state-of-the-art measurements: the non-local resistance of a graphene Hall bar and the transfer characteristic of a WS2 field-effect transistor. Our system allows the quick characterisation of novel insulating states in two-dimensional materials with potential applications in future quantum technologies.J.D.M. acknowledges financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom, via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1). S.F.R acknowledges financial support from the Higher Committee for Education Development in Iraq (HCED). S.R. and M.F.C. 13 acknowledge financial support from EPSRC (Grant no. EP/K010050/1, EP/M001024/1, EP/M002438/1), from Royal Society international Exchanges Scheme 2016/R1, from The Leverhulme trust (grant title ”Quantum Revolution”). A.D.S, S.R. and M.F.C. acknowledge financial support from Royal Society international Exchanges Grant ”Energy Harvesting Fabric”

Graphene coated fabrics by ultrasonic spray coating for wearable electronics and smart textiles

This is the author accepted manuscript. The final version is available on open access from IOP Publishing via the DOI in this recordThe seamless incorporation of electronics in textiles have the potential to enable various applications ranging from sensors for the internet of things to personalised medicine and human-machine interfacing. Graphene electronic textiles are a current focus for the research community due to the exceptional electrical and optical properties combined with the high flexibility of this material, which makes it the most effective strategy to achieve ultimate mechanical robustness of electronic devices for textile integrated electronics. An efficient way to create electronic textiles is to fabricate devices directly on the fabric. This can be done by coating the textile fabric with graphene to make it conductive. Here we discuss successful and efficient methods for coating graphene nanoplatelets (GNPs) on textile substrates of nylon, polyester and meta-aramid using ultrasonic spray coating technique. These coatings are characterised by scanning electron microscopy, contact angle and electrical conductivity measurements in order to identify the optimal textile electrode. Our study provides the foundation for the large-area fabrication of graphene electronic textiles.Engineering and Physical Sciences Research Council (EPSRC

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

EVALITA Evaluation of NLP and Speech Tools for Italian - December 17th, 2020

Welcome to EVALITA 2020! EVALITA is the evaluation campaign of Natural Language Processing and Speech Tools for Italian. EVALITA is an initiative of the Italian Association for Computational Linguistics (AILC, http://www.ai-lc.it) and it is endorsed by the Italian Association for Artificial Intelligence (AIxIA, http://www.aixia.it) and the Italian Association for Speech Sciences (AISV, http://www.aisv.it)

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Building a WordNet for Arabic

This paper introduces a recently initiated project that focuses on building a lexical resource for Modern Standard Arabic based on the widely used Princeton WordNet for English (Fellbaum, 1998). Our aim is to develop a linguistic resource with a deep formal semantic foundation in order to capture the richness of Arabic as described in Elkateb (2005). Arabic WordNet is being constructed following methods developed for EuroWordNet (Vossen, 1998). In addition to the standard wordnet representation of senses, word meanings are also being defined with a machine understandable semantics in first order logic. The basis for this semantics is the Suggested Upper Merged Ontology and its associated domain ontologies (Niles and Pease, 2001). We will greatly extend the ontology and its set of mappings to provide formal terms and definitions for each synset. Tools to be developed as part of this effort include a lexicographer's interface modeled on that used for EuroWordNet, with added facilities for Arabic script, following Black and Elkateb's earlier work (2004)

Graphene coated fabrics by ultrasonic spray coating for wearable electronics and smart textiles

The seamless incorporation of electronics in textiles have the potential to enable various applications ranging from sensors for the internet of things to personalised medicine and human-machine interfacing. Graphene electronic textiles are a current focus for the research community due to the exceptional electrical and optical properties combined with the high flexibility of this material, which makes it the most effective strategy to achieve ultimate mechanical robustness of electronic devices for textile integrated electronics. An efficient way to create electronic textiles is to fabricate devices directly on the fabric. This can be done by coating the textile fabric with graphene to make it conductive. Here we discuss successful and efficient methods for coating graphene nanoplatelets on textile substrates of nylon, polyester and meta-aramid using ultrasonic spray coating technique. These coatings are characterised by scanning electron microscopy, contact angle and electrical conductivity measurements in order to identify the optimal textile electrode. Our study provides the foundation for the large-area fabrication of graphene electronic textiles