Search results for " Phase"

showing 10 items of 1862 documents

Mean-field theory for superconductivity in twisted bilayer graphene

2018

Recent experiments show how a bilayer graphene twisted around a certain magic angle becomes superconducting as it is doped into a region with approximate flat bands. We investigate the mean-field s-wave superconducting state in such a system and show how the state evolves as the twist angle is tuned, and as a function of the doping level. We argue that part of the experimental findings could well be understood to result from an attractive electron-electron interaction mediated by electron-phonon coupling, but the flat-band nature of the excitation spectrum also makes the superconductivity quite unusual. For example, as the flat-band states are highly localized around certain spots in the st…

superconducting phase transitionsuperconducting gapsuprajohtavuusCondensed Matter::Superconductivitygrafeenisuperconducting order parameter
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Superfluid weight and Berezinskii-Kosterlitz-Thouless transition temperature of twisted bilayer graphene

2019

We study superconductivity of twisted bilayer graphene with local and non-local attractive interactions. We obtain the superfluid weight and Berezinskii-Kosterlitz-Thouless (BKT) transition temperature for microscopic tight-binding and low-energy continuum models. We predict qualitative differences between local and non-local interaction schemes which could be distinguished experimentally. In the flat band limit where the pair potential exceeds the band width we show that the superfluid weight and BKT temperature are determined by multiband processes and quantum geometry of the band.

suprajohtavuusINSULATORsuperfluid densitymultiband superconductivityFOS: Physical sciences02 engineering and technologyBKT transition01 natural sciences114 Physical sciencessuperconducting phase transitionSuperconductivity (cond-mat.supr-con)SuperfluidityMAGIC-ANGLEsuperconducting fluctuationsnanorakenteetCondensed Matter::SuperconductivityMesoscale and Nanoscale Physics (cond-mat.mes-hall)0103 physical sciencesgrafeeni010306 general physicsQuantumPhysicsSuperconductivityCondensed Matter::Quantum GasesCondensed matter physicsCondensed Matter - Mesoscale and Nanoscale PhysicsCondensed Matter::OtherSUPERCONDUCTIVITYCondensed Matter - SuperconductivityORDER021001 nanoscience & nanotechnologySTATEsuperconducting RFKosterlitz–Thouless transitionPairingDENSITYBerry connection and curvature0210 nano-technologyBilayer graphene
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Surfactant self-assembling in the gas phase: bis(2-ethylhexyl)- sulfosuccinate divalent metal ion anionic aggregates

2012

RATIONALE: Investigation of fundamental aspects driving surfactant self-assembling and of the capability of including guest molecules or ions in their micellar aggregates is an exciting research field for theoretical and technological reasons. In this light, assembling and chelating properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) towards divalent metal ion chlorides have been investigated in the gas phase by electrospray ionization mass spectrometry in negative ion mode, tandem mass spectrometry and energy-resolved mass spectrometry. METHODS:Water/methanol solutions of AOTNa and chloride salts of nickel, magnesium, calcium and manganese, with different AOTNa/metal salt ratios, …

surfactant self-assembling gas phase divalent metal ion anionic aggregates mass spectrometrySettore CHIM/06 - Chimica Organica
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Gas Phase Charged Aggregates of Bis(2-ethylhexyl)sulfo-succinate (AOT) and Divalent Metal Ions. First evidence of AOT solvated aggregates

2011

Assembling and chelating properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) towards divalent metal ions have been investigated in the gas phase by electrospray ionization mass spectrometry. A variety of positively charged monometallated and mixed metal aggregates are formed. Interestingly, several ions contain solvent (MeOH, H2O) molecules and constitute the most abundant AOT cationic aggregates not containing sodium. These species are the first example of solvated AOT-metal ion aggregates in the gas phase. By increasing the surfactant aggregation number, the abundance of solvated species becomes lower than that of unsolvated ones. Decompositions of ionic species have been studied…

surfactantAOTGas phase aggregateelectrosprayenergy resolved mass spectrometrySettore CHIM/02 - Chimica Fisica
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Review: Mass spectrometry of surfactant aggregates

2011

In contrast with the enormous amount of literature produced during many decades in the field of surfactant aggregation in liquid, liquid crystalline and solid phases, only a few investigations concerning surfactant self-assembling in the gas phase as charged aggregates have been carried out until now. This lack of interest is disappointing in view of the remarkable theoretical and practical importance of the inherent knowledge. The absence of surfactant–solvent interactions makes it easier to study the role of surfactant–surfactant forces in determining their peculiar self-assembling features as well as the ability of these assemblies to incorporate selected solubilizate molecules. Thus, th…

surfactants charged aggregates gas phase reverse micelles mass spectrometry ESI-MS
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Computing the Trace

2001

So far we have been interested in the general expression for the WKB-propagation function. Now we turn our attention to the trace of that propagator, since we want to exhibit the energy eigenvalues of a given potential. From earlier discussions we know that the energy levels of a given Hamiltonian are provided by the poles of the Green’s function:

symbols.namesakeTheoretical physicsComputer sciencesymbolsPropagatorStationary phase approximationGeneral expressionHamiltonian (quantum mechanics)Eigenvalues and eigenvectors
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Convolutional neural networks in skin cancer detection using spatial and spectral domain

2019

Skin cancers are world wide deathly health problem, where significant life and cost savings could be achieved if detection of cancer can be done in early phase. Hypespectral imaging is prominent tool for non-invasive screening. In this study we compare how use of both spectral and spatial domain increase classification performance of convolutional neural networks. We compare five different neural network architectures for real patient data. Our models gain same or slightly better positive predictive value as clinicians. Towards more general and reliable model more data is needed and collection of training data should be systematic. peerReviewed

ta113Training setskin cancerArtificial neural networkComputer sciencebusiness.industryspektrikuvausHyperspectral imagingspectral imagingSpectral domainPattern recognitionneuroverkotmedicine.diseaseneural networksWorld wideConvolutional neural networkihosyöpämedicineArtificial intelligenceSkin cancerEarly phasebusinessta217
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Il primo concorso per il Palazzo di Giustizia a Roma del 1884. Ricostruzione critica del progetto di Ernesto Basile

2019

1. Breve descrizione dell’oggetto di studio Il concorso del Palazzo di Giustizia di Roma si svolge in quattro fasi svolte tra il 1884 e il 1887. Il progetto per il primo concorso, del 1884, redatto dall’allora giovanissimo Ernesto Basile (Palermo 1857-1932), rivela una grande perizia progettuale che trasforma il complesso programma funzionale in un austero edificio in stile neofiorentino. I disegni originari dell’opera, non realizzata, conservati presso la Dotazione Basile del Dipartimento di Architettura dell’Università di Palermo, sono stati oggetto di studio propedeutico alle fasi di analisi, interpretazione e ricostruzione congetturale del modello digitale. 2. Stato dell’arte e riferime…

the spatiality of the great vestibule• elaboration of axonometric and perspective view• choice of interpretation criteria in case of project incongruitiethe vaulted arcades.the space of the main courtyard which Basile outlines in a sketch• elaboration of analytical drawings (modular functional compositional volumetric schemes)• modular study and flat vectorization• application of rendering techniques consistent with the available information. 4. Objectives pursued and achieved Conjectural reconstruction achieved the following results: • formulation of analytical documents which show how the planimetric and altimetric articulation are perfectly consistent with the functional program• definition of the level of uncertainty1. Brief description of the object of study The competition of the Palace of Justice in Rome takes place in four phases between 1884 and 1887. The project for the first competition in 1884 drawn up by the then very young Ernesto Basile (Palermo 1857-1932) reveals a great deal of design expertise that transforms the complex functional program into an austere building in neo-florentine style. The original drawings of the building not realized kept in the Basile Endowment of the Department of Architecture of the University of Palermo have been the subject of preliminary study to the phases of analysis interpretation and conceptual reconstruction of the digital model. 2. State of the art and main bibliographical references The conjectural reconstruction on the basis of drawings and archival documents is a well-established and codified practice thanks to various disciplinary contributions at national and international level. See: F. I. Apollonio Classification Schemes for Visualization of Uncertainty in Digital Hypothetical Reconstruction in M. Sander P. Mieke P. Kuroczyński M. Ioannides 3D Research Challenges in Cultural Heritage II Cham (CH) 2016. G. Antista M. Cannella Ricostruire. Architettura - Storia – Rappresentazione Palermo 2015. For studies related to the examinated project see: E. Mauro E. Sessa I disegni della Collezione Basile Roma 2015. E. Sessa Ernesto Basile. Dall'eclettismo Classicista al Modernismo Palermo 2002. 3. Definition of the methodologies adopted in the research Methodological phases: • historical analysi• survey of the original drawings and dimensional verification of the flat scanSettore ICAR/17 - Disegno• construction of perspective views deduced from the original drawings that highlight: the volumetric hierarchy and the function of the bugnate in the scanning of the masonry ma• three-dimensional modeling
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Modeling and experimental approaches for the characterization of phase equilibria in polymer solutions

2012

thermodynamicoptical measurementsliquid-liquid phase separationPolymer solution
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Calculation of ternary polymer solution phase diagram via compressible lattice fluid model extended to specific interactions

2012

Ternary polymer solutions are currently employed for the production of porous structures (e.g. membranes and scaffolds for tissue engineering) via liquid-liquid phase separation techniques. The relation between processing conditions and thermodynamic features of the considered polymeric system determines the morphology of the as-prepared membrane. Therefore, in order to achieve a better control on a porous structure, a deep characterization of the phase behavior of a polymer solution is needed. The experimental derivation of phase diagrams is highly cost and time consuming, thus usually the cloud point curves of the system are directly measured. In this work, the compressible lattice fluid …

thermodynamicpolymer solutionliquid-liquid phase separation
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