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111.
We study the disordered, multispiral solutions of two-dimensional oscillatory media for parameter values at which the single-spiral/vortex solution is fully stable. Using the complex Ginzburg-Landau (CGLE) equation, we show that these states, heretofore believed to be static, actually evolve extremely slowly. This is achieved via a reduction of the CGLE to the evolution of the sole vortex coordinates. This true defect-mediated turbulence occurs in two distinct phases, a vortex liquid characterized by normal diffusion of spirals, and a slowly relaxing, intermittent, "vortex glass." 相似文献
112.
Transport effects in a monolayer consisting of a binary granular mixture, confined in a horizontally vibrating circular dish, are studied experimentally and compared with a reduced theoretical model. Depending on the ratio of the particles' material density and size, migration of the larger particles occurs either towards the boundary or to the center of the circular container. These directed motions show similarities to the Brazil-nut effect and its reverse form. 相似文献
113.
We present a way of tiling the plane with a regular hexagonal network of defects. The network is stable and follows in consequence of the three-junctions that appear in a model of two real scalar fields that presents Z3 symmetry. The Z3 symmetry is effective in both the vacuum and defect sectors, and no supersymmetry is required to build the network. 相似文献
114.
A. Alves L. Brito M.H. Caldeira J.M. Domingos P. Martins H. Pascoal J. Da Providência M.C. Ruivo E.M. Silva C.A. De Sousa J. Urbano 《Nuclear Physics A》1977,284(3):420-424
A simple criterion for the approximate validity of the single projection Peierls-Yoccoz method is discussed. A procedure for chosing the generator coordinate is proposed. 相似文献
115.
Feifel R Gel'mukhanov F Baev A Agren H Piancastelli MN Bässler M Miron C Sorensen SL Naves De Brito A Björneholm O Karlsson L Svensson S 《Physical review letters》2002,89(10):103002
An interference quenching of the nu(")=1 vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N2 is observed and analyzed. The intensity ratio between the nu(")=1 and nu(")=0 vibrational levels of the X2Sigma(+)(g) final state shows a surprising nonmonotonous variation as a function of frequency detuning, going through a minimum with a complete suppression of nu(")=1. We have developed a simple model which shows a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance R(0)(c) of the core-excited state. A new way is thus established of determining the equilibrium bond distance for the core-excited state with a precision deltaR(0)(c)<10(-3) A. 相似文献
116.
Ultrasonic Doppler velocimetry in liquid gallium 总被引:5,自引:0,他引:5
Daniel Brito Henri-Claude Nataf Philippe Cardin Julien Aubert Jean-Paul Masson 《Experiments in fluids》2001,31(6):653-663
For the first time, flow velocity is measured in a vortex of liquid gallium, using the pulsed Doppler shift ultrasonic method.
At the top of a copper cylinder filled with liquid gallium, we spin a disk and create a turbulent vortex with a dominant nearly
axisymmetric velocity field with little variation in the axial direction. The velocity profiles are shown to be well resolved
and in quantitative agreement with earlier observations. Reliable velocity measurements in liquid gallium could be obtained
only after serious problems due to the formation of oxides were solved. This work opens the way to performing accurate velocity
measurements in other liquid metals; preliminary results for liquid sodium are shown.
Received: 14 January 2000 / Accepted: 12 January 2001 相似文献
117.
Davi Marcelo Soares Dr. Santanu Mukherjee Prof. Gurpreet Singh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(29):6320-6341
Atomically thin sheets of two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted interest as high capacity electrode materials for electrochemical energy storage devices owing to their unique properties (high surface area, high strength and modulus, faster ion diffusion, and so on), which arise from their layered morphology and diversified chemistry. Nevertheless, low electronic conductivity, poor cycling stability, large structural changes during metal-ion insertion/extraction along with high cost of manufacture are challenges that require further research in order for TMDs to find use in commercial batteries and supercapacitors. Here, a systematic review of cutting-edge research focused on TMD materials beyond the widely studied molybdenum disulfide or MoS2 electrode is reported. Accordingly, a critical overview of the recent progress concerning synthesis methods, physicochemical and electrochemical properties is given. Trends and opportunities that may contribute to state-of-the-art research are also discussed. 相似文献
118.
119.
Tert‐butyl hydroperoxide‐promoted guanylation of amines with benzoylthioureas: Mechanistic insights by HRMS and 1H NMR
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Henrique Esteves Tiago Oliveira Brito Renato Ribeiro‐Viana Ângelo de Fátima Fernando Macedo Jr. 《Journal of Physical Organic Chemistry》2017,30(12)
Herein, we present a mechanistic study on tert‐butyl hydroperoxide‐promoted guanylation of thioureas by monitoring short lifetime intermediates using electrospray ionisation/time‐of‐flight high resolution mass spectrometry (ESI‐Q‐TOF HRMS). Moreover, 1H nuclear magnetic resonance data allowed us to access kinetic parameters for the main species involved which, allied to the HRMS results, furnished valuable insights over previously reported observations. The results suggested an addition/elimination mechanism involving the aminoiminomethanesulphinic acid, RNC(SO2H)NHR′, and the nucleophilic amine as the main pathway to yield the guanidine. Noteworthy, benzoylthiourea consumption rate presented a nonlinear kinetic behaviour, while tBuOOH and the nucleophilic amine consumptions were found to follow second‐order kinetics. 相似文献
120.
In this work we consider an application of the deformation procedure that enables us to construct, systematically, scalar field models supporting multikinks. We introduce a new deformation function in order to realize this task. We exemplify the procedure with three different starting models already known in the literature, and the resulting deformed models have rich minima structures which are responsible for the appearance of multikink configurations. We have also considered an application to braneworld scenarios, where we have obtained interesting configurations corresponding to the multikink solutions. 相似文献