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topological phases

Helene Feuillatre, Jean-Claude Nunes, Christine Toumoulin, Helene Feuillatre, Jean-Claude Nunes, Christine Toumoulin, Jean-Claude Nunes, Helene Feuillatre, Christine Toumoulin
Coronary tree matching is applied to plan percutaneous vascular procedures. This work, which allows following each segment of non-isomorphic coronary trees over time, precedes the determination of the best 2D angiography view from C-arm acquisition system for angioplasty procedure. To match two 3D coronary trees which represent two successive cardiac phases, we adapted a reference inexact tree matching algorithm based on association graph and maximum clique. To improve the pair-wise matching performance of our approach, artificial nodes are introduced to take into account the topology variation between 3D vascular trees...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Hui-Lin Huang, Wen-Yen Huang, Sue-Lein Wang
Reproducing inorganic modules in situ for pore augmentation of pure inorganic frameworks is challenging but can be a key to rational synthesis. After the first success of using monoamine of varied lengths as template in producing the same set of building blocks that led to a series of growing channels up to 72-membered ring (72R), we have continued to delve into those building blocks to seek any new topologies from them. In this study, we have discovered another type of template that can control the same building blocks to form in situ repeatedly...
February 22, 2017: Chemistry: a European Journal
Ratnadwip Singha, Arnab Kumar Pariari, Biswarup Satpati, Prabhat Mandal
Whereas the discovery of Dirac- and Weyl-type excitations in electronic systems is a major breakthrough in recent condensed matter physics, finding appropriate materials for fundamental physics and technological applications is an experimental challenge. In all of the reported materials, linear dispersion survives only up to a few hundred millielectronvolts from the Dirac or Weyl nodes. On the other hand, real materials are subject to uncontrolled doping during preparation and thermal effect near room temperature can hinder the rich physics...
February 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
B Dubiel, P Indyka, T Moskalewicz, A Kruk, M Zubko, I Kalemba-Rec, K Berent
A combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning-transmission electron microscopy (STEM) using high-angle annular-dark-field (HAADF) imaging, focussed ion beam- scanning electron microscopy (FIB-SEM) tomography, selected area electron diffraction with beam precession (PED), as well as spatially resolved energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS), was used to investigate topologically close-packed (TCP) phases, occurring in the CMSX-4 superalloy subjected to high temperature annealing and creep deformation...
February 20, 2017: Journal of Microscopy
Svitlana Kondovych, Igor Luk'yanchuk, Tatyana I Baturina, Valerii M Vinokur
The two-dimensional (2D) logarithmic character of Coulomb interaction between charges and the resulting logarithmic confinement is a remarkable inherent property of high dielectric constant (high-κ) thin films with far reaching implications. Most and foremost, this is the charge Berezinskii-Kosterlitz-Thouless transition with the notable manifestation, low-temperature superinsulating topological phase. Here we show that the range of the confinement can be tuned by the external gate electrode and unravel a variety of electrostatic interactions in high-k films...
February 20, 2017: Scientific Reports
Yue Zhang, Bryan E G Lucier, Victor V Terskikh, Renlong Zheng, Yining Huang
Ga-MIL-53 is a metal-organic framework (MOF) that exhibits a "breathing effect," in which the pore size and overall MOF topology can be influenced by temperature, pressure, and host-guest interactions. The phase control afforded by this flexible framework renders Ga-MIL-53 a promising material for guest storage and sensing applications. In this work, the structure and behavior of four Ga-MIL-53 phases (as, ht, enp and lt), along with CO2 adsorbed within Ga-MIL-53 at various loading levels, has been investigated using (69/71)Ga solid-state NMR (SSNMR) experiments at 21...
January 31, 2017: Solid State Nuclear Magnetic Resonance
A Zazunov, F Buccheri, P Sodano, R Egger
We study Majorana devices featuring a competition between superconductivity and multichannel Kondo physics. Our proposal extends previous work on single-channel Kondo systems to a topologically nontrivial setting of a non-Fermi liquid type, where topological superconductor wires (with gap Δ) represent leads tunnel coupled to a Coulomb-blockaded Majorana box. On the box, a spin degree of freedom with Kondo temperature T_{K} is nonlocally defined in terms of Majorana states. For Δ≫T_{K}, the destruction of Kondo screening by superconductivity implies a 4π-periodic Josephson current-phase relation...
February 3, 2017: Physical Review Letters
José A Carrasco, Federico Finkel, Artemio González-López, Miguel A Rodríguez
We study the critical behavior and the ground-state entanglement of a large class of su(1|1) supersymmetric spin chains with a general (not necessarily monotonic) dispersion relation. We show that this class includes several relevant models, with both short- and long-range interactions of a simple form. We determine the low temperature behavior of the free energy per spin, and deduce that the models considered have a critical phase in the same universality class as a (1+1)-dimensional conformal field theory (CFT) with central charge equal to the number of connected components of the Fermi sea...
January 2017: Physical Review. E
Debsankha Manik, Martin Rohden, Henrik Ronellenfitsch, Xiaozhu Zhang, Sarah Hallerberg, Dirk Witthaut, Marc Timme
We introduce the concept of network susceptibilities quantifying the response of the collective dynamics of a network to small parameter changes. We distinguish two types of susceptibilities: vertex susceptibilities and edge susceptibilities, measuring the responses due to changes in the properties of units and their interactions, respectively. We derive explicit forms of network susceptibilities for oscillator networks close to steady states and offer example applications for Kuramoto-type phase-oscillator models, power grid models, and generic flow models...
January 2017: Physical Review. E
Tommy Dessup, Christophe Coste, Michel Saint Jean
We study the path toward equilibrium of pairs of solitary wave envelopes (bubbles) that modulate a regular zigzag pattern in an annular channel. We evidence that bubble pairs are metastable states, which spontaneously evolve toward a stable single bubble. We exhibit the concept of topological frustration of a bubble pair. A configuration is frustrated when the particles between the two bubbles are not organized in a modulated staggered row. For a nonfrustrated (NF) bubble pair configuration, the bubbles interaction is attractive, whereas it is repulsive for a frustrated (F) configuration...
January 2017: Physical Review. E
Chongpu Zhai, Dorian Hanaor, Yixiang Gan
In this paper we apply lattice models of finite binary percolation networks to examine the effects of network configuration on macroscopic network responses. We consider both square and rectangular lattice structures in which bonds between nodes are randomly assigned to be either resistors or capacitors. Results show that for given network geometries, the overall normalised frequency-dependent electrical conductivities for different capacitor proportions are found to converge at a characteristic frequency. Networks with sufficiently large size tend to share the same convergence point uninfluenced by the boundary and electrode conditions, can be then regarded as homogeneous media...
2017: PloS One
Hailiang Zhao, Xiaotong Jiang, Lin Du
Methane sulfonic acid (MSA) is present in substantial concentrations in the gas phase over oceans and coastal regions. We present an investigation into the contribution of MSA to new particle formation with the common atmospheric aerosol nucleation precursors including MSA, methanol, formic acid, acetone, dimethylether, formaldehyde, methyl formate, by making use a quantum chemical approach. Density functional theory calculations indicate that these bimolecular complexes are characterized by the presence of strong inter-molecular hydrogen bonds (SOH⋯O) with large binding energies and thermodynamic equilibrium constants...
February 7, 2017: Chemosphere
Martin Urbanski, Catherine G Reyes, JungHyun Noh, Anshul Sharma, Yong Geng, Venkata Subba Rao Jampani, Jan P F Lagerwall
The extraordinary responsiveness and large diversity of self-assembled structures of liquid crystals are well documented and they have been extensively used in devices like displays. For long, this application route strongly influenced academic research, which frequently focused on the performance of liquid crystals in display-like geometries, typically between flat, rigid substrates of glass or similar solids. Today a new trend is clearly visible, where liquid crystals confined within curved, often soft and flexible, interfaces are in focus...
February 15, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Tim A Wezendonk, Quirinus S E Warringa, Vera P Santos, Adam Chojecki, Matthijs Ruitenbeek, Garry Meima, Michiel Makkee, Freek Kapteijn, Jorge Gascon
The structure and elementary composition of various commercial Fe-based MOFs used as precursors for Fischer-Tropsch synthesis (FTS) catalysts have a large influence on the high-temperature FTS activity and selectivity of the resulting Fe on carbon composites. The selected Fe-MOF topologies (MIL-68, MIL-88A, MIL-100, MIL-101, MIL-127, and Fe-BTC) differ from each other in terms of porosity, surface area, Fe and heteroatom content, crystal density and thermal stability. They are re-engineered towards FTS catalysts by means of simple pyrolysis at 500 °C under a N2 atmosphere and afterwards characterized in terms of porosity, crystallite phase, bulk and surface Fe content, Fe nanoparticle size and oxidation state...
February 14, 2017: Faraday Discussions
Yunfeng Li, Elisabeth Prince, Sangho Cho, Alinaghi Salari, Youssef Mosaddeghian Golestani, Oleg D Lavrentovich, Eugenia Kumacheva
An important goal of the modern soft matter science is to discover new self-assembly modalities to precisely control the placement of small particles in space. Spatial inhomogeneity of liquid crystals offers the capability to organize colloids in certain regions such as the cores of the topological defects. Here we report two self-assembly modes of nanoparticles in linear defects-disclinations in a lyotropic colloidal cholesteric liquid crystal: a continuous helicoidal thread and a periodic array of discrete beads...
February 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
M Barrio, J Huguet, I B Rietveld, B Robert, R Céolin, J Ll Tamarit
Understanding the polymorphic behavior of active pharmaceutical ingredients is important for formulation purposes and regulatory reasons. Metacetamol is an isomer of paracetamol and it similarly exhibits polymorphism. In the present paper, it has been found that one of the polymorphs of metacetamol is only stable under increased pressure, which has led to the conclusion that metacetamol like paracetamol is a monotropic system under ordinary (= laboratory) conditions and that it becomes enantiotropic under pressure with the I-II-L triple point coordinates for metacetamol TI-II-L = 535±10 K and PI-II-L = 692±70 MPa...
February 9, 2017: Journal of Pharmaceutical Sciences
Sung Hyun Yoo, Hee-Seung Lee
The wide range of fascinating supramolecular architectures found in nature, from DNA double helices to giant protein shells, inspires researchers to mimic the diverse shapes and functions of natural systems. Thus, a variety of artificial molecular platforms have been developed by assembling DNA-, peptide-, and protein-based building blocks for medicinal and biological applications. There has also been a significant interest in the research of non-natural oligomers (i.e., foldamers) that fold into well-defined secondary structures analogous to those found in proteins, because the assemblies of foldamers are expected not only to form biomimetic supramolecular architectures that resemble those of nature but also to display unique functions and unprecedented topologies at the same time due to their different folding propensities from those of natural building blocks...
February 13, 2017: Accounts of Chemical Research
M Mogi, M Kawamura, R Yoshimi, A Tsukazaki, Y Kozuka, N Shirakawa, K S Takahashi, M Kawasaki, Y Tokura
The axion insulator which may exhibit an exotic quantized magnetoelectric effect is one of the most interesting quantum phases predicted for the three-dimensional topological insulator (TI). The axion insulator state is expected to show up in magnetically doped TIs with magnetizations pointing inwards and outwards from the respective surfaces. Towards the realization of the axion insulator, we here engineered a TI heterostructure in which magnetic ions (Cr) are modulation-doped only in the vicinity of the top and bottom surfaces of the TI ((Bi,Sb)2Te3) film...
February 13, 2017: Nature Materials
S Eley, M Miura, B Maiorov, L Civale
Superconductors are excellent testbeds for studying vortices, topological excitations that also appear in superfluids, liquid crystals and Bose-Einstein condensates. Vortex motion can be disruptive; it can cause phase transitions, glitches in pulsars, and losses in superconducting microwave circuits, and it limits the current-carrying capacity of superconductors. Understanding vortex dynamics is fundamentally and technologically important, and the competition between thermal energy and energy barriers defined by material disorder is not completely understood...
February 13, 2017: Nature Materials
Aleksandre Japaridze, Georgi Muskhelishvili, Fabrizio Benedetti, Agni Gavriilidou, Renato Zenobi, Paolo De Los Rios, Giovanni Longo, Giovanni Dietler
Bacterial chromosome has a compact structure that dynamically changes its shape in response to bacterial growth rate and growth phase. Determining how chromatin remains accessible to DNA binding proteins and transcription machinery is crucial to understand the link between genetic regulation, DNA structure and topology. Here, we study very large supercoiled dsDNA using high-resolution characterization, theoretical modelling and molecular dynamics calculations. We unveil a new type of highly ordered DNA organization forming in the presence of attractive DNA-DNA interactions, which we call hyperplectonemes...
February 13, 2017: Nano Letters
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