1,141 research outputs found
Josephson current via an isolated Majorana zero mode
No full textWe study the equilibrium dc Josephson current in a junction between an s-wave and a topological superconductor. Cooper pairs from the s-wave superconducting lead can transfer to the topological side either via an unpaired Majorana zero mode localized near the junction or via the above-gap continuum states. We find that the Majorana contribution to the supercurrent can be switched on when time-reversal symmetry in the conventional lead is broken, e.g., by an externally applied magnetic field inducing a Zeeman splitting. Moreover, if the magnetic field has a component in the direction of the effective spin-orbit field, there will be a Majorana-induced anomalous supercurrent at zero phase difference. These behaviors may serve as a signature characteristic of Majorana zero modes and are accessible to devices with only superconducting contacts.QRD/Wimmer GroupBUS/Quantum Delf
Sujet, mémoire et quotidien dans les récits de Valérie Mréjen
No full textWriter, visual artist and video artist Valérie Mréjen writes texts and screenplays that portray the everyday reality of her autofictional narrator and her characters. Everyday life, everyday incidents and mealtime routines, reading and grandparents' stories are, for example, among the subjects covered in the Trois quartiers trilogy (including Mon grand-père (Allia 1999), Agrume (Allia 2001), and Eau sauvage (Allia 2004), published together in 2005 by J'ai lu). Her discreetly autobiographical narratives continue in Forêt noire (POL 2012), a novel in which she recalls stories heard in the past, and in Troisième personne (POL 2017), in which she explores the changes in a family after the arrival of a child. In all her stories and novels, the author goes in search of the most intimate and concrete memories, which she reproduces in small narrative forms, recounting the most banal realities and the greatest truths of life and interpersonal relationships. Drawing on Henry Lefevbre's and Michel de Certeau's reflections on the everyday, as well as Michael Sheringham's, and reading Valérie Mréjen's narratives, the article explores the banality of the everyday in the light of the following questions: how does the narrator/speaker construct him/herself as a person by rubbing shoulders with the real? could we envisage a will of the narrator/speaker to be the subject of a narrative of his/her everyday life?Écrivaine, plasticienne et vidéaste, Valérie Mréjen écrit des textes et des scénarios qui mettent en scène la réalité quotidienne de sa narratrice autofictionnelle et de ses personnages. La vie de tous les jours, les petits incidents quotidiens et la routine des repas, les lectures et les récits des grands-parents sont, par exemple, parmi les sujets abordés dans la trilogie Trois quartiers (comprenant Mon grand-père (Allia 1999), Agrume (Allia 2001), et Eau sauvage (Allia 2004), publiés ensemble en 2005 par J’ai lu). Ses narrations discrètement autobiographiques se poursuivent ensuite avec Forêt noire (POL 2012), roman où elle se remémore d’histoires entendues dans le passé et dans Troisième personne (POL 2017) où elle sonde les changements intervenus dans une famille après l’arrivée d’un enfant. Dans tous ses récits et romans, l’autrice s’élance à la recherche des souvenirs les plus intimes et les plus concrets qu’elle reproduit dans des petites formes narratives, en racontant la réalité la plus banale et les plus grandes vérités de la vie et des relations interpersonnelles. À partir des réflexions sur le quotidien d’Henry Lefevbre et de Michel de Certeau ainsi que de celles de Michael Sheringham, par la lecture des récits de Valérie Mréjen l'article sonde la banalité du quotidien à la lumière des questionnements suivants : comment le sujet narrateur/locuteur se construit-il en tant que personne par le frottement avec le réel ? est-ce que nous pourrions envisager une volonté d’enquêter sur le sujet contemporain par le récit de son quotidien ? est-ce que le récit du quotidien peut raconter les personnes qui le vivent
Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates
No full textThis is the accepted version of the following article: Matsude A., Hirano K., Miura M.. Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates. Advanced Synthesis and Catalysis 362, 518 (2020), which has been published in final form at https://doi.org/10.1002/adsc.201901398. This article may be used for non-commercialpurposes in accordance with the Wiley Self-ArchivingPolicy [https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html]A palladium-catalyzed intramolecular Mizoroki-Heck-type reaction of diarylmethyl tert-butyl carbonates has been developed. The reaction proceeds under external base-free, neutral conditions to form the corresponding methyleneindanes in good yields only with liberation of CO2 and tBuOH. The resulting exo-methylene moiety is reactive and thus a good synthetic handle for further manipulations. Additionally, the asymmetric synthesis is also possible through a Pd/chiral Mandyphos ligand-mediated kinetic resolution. To the best of our knowledge, this is the first successful example of catalytic enantioselective Mizoroki-Heck-type reaction of secondary benzyl electrophiles. (Figure presented.)
Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates
No full textThis is the accepted version of the following article: Matsude A., Hirano K., Miura M.. Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates. Advanced Synthesis and Catalysis 362, 518 (2020), which has been published in final form at https://doi.org/10.1002/adsc.201901398. This article may be used for non-commercialpurposes in accordance with the Wiley Self-ArchivingPolicy [https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html]A palladium-catalyzed intramolecular Mizoroki-Heck-type reaction of diarylmethyl tert-butyl carbonates has been developed. The reaction proceeds under external base-free, neutral conditions to form the corresponding methyleneindanes in good yields only with liberation of CO2 and tBuOH. The resulting exo-methylene moiety is reactive and thus a good synthetic handle for further manipulations. Additionally, the asymmetric synthesis is also possible through a Pd/chiral Mandyphos ligand-mediated kinetic resolution. To the best of our knowledge, this is the first successful example of catalytic enantioselective Mizoroki-Heck-type reaction of secondary benzyl electrophiles. (Figure presented.)
Information handling in astronomy : beyond technologies and methodologies
No full textA few comments are offered in the light of about thirty years of activities linked to the information flow in astronomy and of about two decades of blossoming of electronic networks and tools including the World-Wide Web. Some points are emphasized (such as the changing sociology of data centres) and wrong expectations are pointed out (such as the all-electronic era)
Semi-síntese de derivados dos triterpenos a e ß-amirina e síntese de estirilpironas via arilação de Heck com sais de arenodiazônio
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química.Neste trabalho relatamos a obtenção de derivados sintéticos de uma mistura dos triterpenos ? e ?-amirina, os quais foram avaliados quanto aos seus efeitos leishmanicida e citotóxico. Os derivados 31 e 45 exibiram efeito leishmanicida 5 vezes mais potente que a anfotericina B e os derivados 35 e 36 exibiram significante efeito citotóxico contra células tumorais testadas. Além disso, foram realizados experimentos na tentativa de determinar o mecanismo de ação antinociceptiva do derivado octanoato de ? e ?-amirina. A segunda parte do trabalho trata de um estudo da relação entre a estrutura das estirilpironas naturais, previamente isoladas de Polygala sabulosa, e sua afinidade pelo sítio bezodiazepínico. O estudo foi realizado utilizando o funcional de densidade (DFT) como ferramenta teórica. Estes resultados nos orientaram no planejamento e síntese de análogos das estirilpironas naturais visando aumentar a afinidade pelo sítio benzodiazepínico. Desta forma, foi desenvolvida uma nova metodologia, em colaboração com o grupo do Prof. Dr. Carlos R. D. Correia, da UNICAMP, via arilação de Heck com sais de arenodiazônio. Foram preparados 12 compostos diretamente através da reação de Heck-Matsuda e mais 5 compostos via reações de hidrogenação catalítica e demetilação dos adutos de Heck. Estes compostos não exibiram efeito tóxico em células tumorais na concentração de 50,0 µM
Carbon dioxide pressure induced heterogeneous and homogeneous Heck and Sonogashira coupling reactions using fluorinated palladium complex catalysts
No full textThe Heck reaction of iodobenzene and methyl acrylate was investigated with CO2-philic Pd complex catalysts having fluorous ponytails and the organic base triethylamine (Et3N) in the presence of CO2 under solventless conditions at 80℃. The catalysts are not soluble in the organic phase in the absence of CO2 and the reaction occurs in a solid-liquid biphasic system. When the organic liquid mixture is pressurized by CO2, CO2 is dissolved into the organic phase and this promotes the dissolution of the Pd complex catalysts. As a result, the Heck reaction occurs homogeneously in the organic phase, which enhances the rate of reaction. This positive effect of CO2 pressurization competes with the negative effect that the reacting species are diluted by an increasing amount of CO2 molecules dissolved. Thus, the maximum conversion appears at a CO2 pressure of around 4 MPa under the present reaction conditions. The catalysts are separated in the solid granules by depressurization and are recyclable without loss of activity after washing with n-hexane and/or water. When the washing is made with hexane alone, the catalytic activity tends to increase on the repeated Heck reactions, probably due to the accumulation of such a base adduct as Et3NHI on the catalysts. When the washing is further made with water, however. the base adduct is taken off from the catalysts and they show similar activity levels in the repeated runs. The potential of CO2 pressure tunable heterogeneous/homogeneous reaction system has also been investigated for Sonogashira reactions of iodobenzene and phenylacetylene under similar conditions
Unified numerical approach to topological semiconductor-superconductor heterostructures
No full textWe develop a unified numerical approach for modeling semiconductor-superconductor heterostructures. All the key physical ingredients of these systems - orbital effect of magnetic field, superconducting proximity effect, and electrostatic environment - are taken into account on equal footing in a realistic device geometry. As a model system, we consider indium arsenide (InAs) nanowires with an epitaxial aluminum (Al) shell, which is one of the most promising platforms for Majorana zero modes. We demonstrate qualitative and quantitative agreement of the obtained results with the existing experimental data. Finally, we characterize the topological superconducting phase emerging in a finite magnetic field and calculate the corresponding topological phase diagram.QRD/Wimmer Grou
Flow Heck Reactions Using Extremely Low Loadings of Phosphine-Free Palladium Acetate
No full textHigh-yielding Heck reactions are demonstrated using 0.05 mol % Pd(OAc)2 without phosphine ligands. These reactions are run in a mesoscale flow reactor which allows precise control of reaction times and temperatures. Profiling yield and selectivity versus Pd loading shows 500 ppm to be optimal for aryl iodides; higher loadings favor side reactions caused by Pd(II) species. Aryl halides are examined via concise Design of Experiment to expand the scope and optimize conditions
Long-term effects of catheter ablation for lone atrial fibrillation: progressive atrial electroanatomic substrate remodeling despite successful ablation
No full textBackgroundWhether curative ablation can prevent progression of the atrial electroanatomic remodeling associated with atrial fibrillation (AF) is not known.ObjectiveThe purpose of this study was to determine whether successful radiofrequency ablation (RFA) of AF can prevent progression of the atrial substrate associated with AF.MethodsDetailed right atrial electroanatomic maps from 11 patients without apparent structural heart disease undergoing RFA of AF at baseline and ≥6 months following successful RFA were compared to 11 control patients undergoing electrophysiologic evaluation of supraventricular tachycardia. Bipolar voltage, conduction, effective refractory periods (ERPs), and signal complexity were assessed.ResultsAt baseline compared with the control group, the AF group demonstrated (1) lower voltage (P ConclusionPatients with lone AF demonstrate evidence of an abnormal atrial substrate at baseline compared to control patients without AF. This substrate does not appear to reverse even after successful catheter ablation. These findings may have implications for long-term outcomes of ablation and for timing of ablative intervention.Andrew W. Teh, Peter M. Kistler, Geoffrey Lee, Caroline Medi, Patrick M. Heck, Steven J. Spence, Joseph B. Morton, Prashanthan Sanders and Jonathan M. Kalma
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