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Malomed BA. Discrete and Semi-Discrete Multidimensional Solitons and Vortices: Established Results and Novel Findings. Entropy (Basel) 2024; 26:137. [PMID: 38392392 PMCID: PMC10887582 DOI: 10.3390/e26020137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/24/2024]
Abstract
This article presents a concise survey of basic discrete and semi-discrete nonlinear models, which produce two- and three-dimensional (2D and 3D) solitons, and a summary of the main theoretical and experimental results obtained for such solitons. The models are based on the discrete nonlinear Schrödinger (DNLS) equations and their generalizations, such as a system of discrete Gross-Pitaevskii (GP) equations with the Lee-Huang-Yang corrections, the 2D Salerno model (SM), DNLS equations with long-range dipole-dipole and quadrupole-quadrupole interactions, a system of coupled discrete equations for the second-harmonic generation with the quadratic (χ(2)) nonlinearity, a 2D DNLS equation with a superlattice modulation opening mini-gaps, a discretized NLS equation with rotation, a DNLS coupler and its PT-symmetric version, a system of DNLS equations for the spin-orbit-coupled (SOC) binary Bose-Einstein condensate, and others. The article presents a review of the basic species of multidimensional discrete modes, including fundamental (zero-vorticity) and vortex solitons, their bound states, gap solitons populating mini-gaps, symmetric and asymmetric solitons in the conservative and PT-symmetric couplers, cuspons in the 2D SM, discrete SOC solitons of the semi-vortex and mixed-mode types, 3D discrete skyrmions, and some others.
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Affiliation(s)
- Boris A Malomed
- Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica 1000000, Chile
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2
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Saravanakumar SM, Cicek PV. Microfluidic Mixing: A Physics-Oriented Review. Micromachines (Basel) 2023; 14:1827. [PMID: 37893264 PMCID: PMC10609072 DOI: 10.3390/mi14101827] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 09/22/2023] [Accepted: 09/24/2023] [Indexed: 10/29/2023]
Abstract
This comprehensive review paper focuses on the intricate physics of microfluidics and their application in micromixing techniques. Various methods for enhancing mixing in microchannels are explored, with a keen emphasis on the underlying fluid dynamics principles. Geometrical micromixers employ complex channel designs to induce fluid-fluid interface distortions, yielding efficient mixing while retaining manufacturing simplicity. These methods synergize effectively with external techniques, showcasing promising potential. Electrohydrodynamics harnesses electrokinetic phenomena like electroosmosis, electrophoresis, and electrothermal effects. These methods offer dynamic control over mixing parameters via applied voltage, frequency, and electrode positioning, although power consumption and heating can be drawbacks. Acoustofluidics leverages acoustic waves to drive microstreaming, offering localized yet far-reaching effects. Magnetohydrodynamics, though limited in applicability to certain fluids, showcases potential by utilizing magnetic fields to propel mixing. Selecting an approach hinges on trade-offs among complexity, efficiency, and compatibility with fluid properties. Understanding the physics of fluid behavior and rationalizing these techniques aids in tailoring the most suitable micromixing solution. In a rapidly advancing field, this paper provides a consolidated understanding of these techniques, facilitating the informed choice of approach for specific microfluidic mixing needs.
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Affiliation(s)
| | - Paul-Vahe Cicek
- Microtechnologies Integration & Convergence Research Group, Université du Québec à Montréal (UQAM), Montreal, QC H2X 3Y7, Canada
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3
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Mayorga-Martinez CC, Zelenka J, Klima K, Kubanova M, Ruml T, Pumera M. Multimodal-Driven Magnetic Microrobots with Enhanced Bactericidal Activity for Biofilm Eradication and Removal from Titanium Mesh. Adv Mater 2023; 35:e2300191. [PMID: 36995927 DOI: 10.1002/adma.202300191] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 03/12/2023] [Indexed: 06/09/2023]
Abstract
Modern micro/nanorobots can perform multiple tasks for biomedical and environmental applications. Particularly, magnetic microrobots can be completely controlled by a rotating magnetic field and their motion powered and controlled without the use of toxic fuels, which makes them most promising for biomedical application. Moreover, they are able to form swarms, allowing them to perform specific tasks at a larger scale than a single microrobot. In this work, they developed magnetic microrobots composed of halloysite nanotubes as backbone and iron oxide (Fe3 O4 ) nanoparticles as magnetic material allowing magnetic propulsion and covered these with polyethylenimine to load ampicillin and prevent the microrobots from disassembling. These microrobots exhibit multimodal motion as single robots as well as in swarms. In addition, they can transform from tumbling to spinning motion and vice-versa, and when in swarm mode they can change their motion from vortex to ribbon and back again. Finally, the vortex motion mode is used to penetrate and disrupt the extracellular matrix of Staphylococcus aureus biofilm colonized on titanium mesh used for bone restoration, which improves the effect of the antibiotic's activity. Such magnetic microrobots for biofilm removal from medical implants could reduce implant rejection and improve patients' well-being.
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Affiliation(s)
- Carmen C Mayorga-Martinez
- Center for Advanced Functional Nanorobots, Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, Prague, 166 28, Czech Republic
| | - Jaroslav Zelenka
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technicka 5, Prague, 166 28, Czech Republic
| | - Karel Klima
- Department of Stomatology - Maxillofacial Surgery, General Teaching Hospital and First Faculty of Medicine, Charles University, Prague, 12808, Czech Republic
| | - Michaela Kubanova
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technicka 5, Prague, 166 28, Czech Republic
| | - Tomas Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technicka 5, Prague, 166 28, Czech Republic
| | - Martin Pumera
- Center for Advanced Functional Nanorobots, Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, Prague, 166 28, Czech Republic
- Faculty of Electrical Engineering and, Computer Science, VSB - Technical University of Ostrava, 17. listopadu 2172/15, Ostrava, 70800, Czech Republic
- Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
- Department of Medical Research, China Medical University Hospital, China Medical University, No. 91 Hsueh-Shih Road, Taichung, 40402, Taiwan
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4
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Feng S, Pan C, Ye H, Liu W, Yang W, Lv Y, Tao S. Magnetic Non-Spherical Particles Inducing Vortices in Microchannel for Effective Mixing. Small 2023; 19:e2207383. [PMID: 36775909 DOI: 10.1002/smll.202207383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 01/20/2023] [Indexed: 05/11/2023]
Abstract
Mixing in microfluidic channels is dominated by diffusion owing to the absence of chaotic flow. However, high-efficiency microscale mixing over short distances is desired for the development of lab-on-chip systems. Here, enhanced mixing in microchannels achieved using magnetic nonspherical particles (MNSPs), is reported. Benefiting from the nonspherical shape of the MNSPs, secondary vortices exhibiting cyclical characteristics appear in microchannels when the MNSPs rotate under an external magnetic field. Increasing the rotation rate enlarges the secondary vortices, expanding the mixing zone and enhancing the mixing, resulting in a mixing efficiency exceeding 0.9 at Re of 0.069-0.69. Complementary micro-particle image velocimetry (µPIV) for flow field analysis clarifies the mixing mechanism. In addition, a chaotic vortex area is generated in the presence of two MNSPs, which shortens the distance required for achieving an appropriate mixing efficiency. This study demonstrates the potential of employing MNSPs as efficient mixers in lab-on-chip devices.
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Affiliation(s)
- Shi Feng
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials Oriented Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
- Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Cunliang Pan
- Department of Engineering Mechanics, State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Hongfei Ye
- Department of Engineering Mechanics, State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Wendong Liu
- Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Wenbo Yang
- Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Yingdi Lv
- Xi'an Modern Chemistry Research Institute, Xi'an, 710065, P. R. China
| | - Shengyang Tao
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials Oriented Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
- Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China
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5
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Diaz-Arriba D, Jardin T, Gourdain N, Pons F, David L. Experiments and numerical simulations on hovering three-dimensional flexible flapping wings. Bioinspir Biomim 2022; 17:065006. [PMID: 36055251 DOI: 10.1088/1748-3190/ac8f06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
In this paper, the applicability and accuracy of high-fidelity experimental and numerical approaches in the analysis of three-dimensional flapping (revolving and pitching) wings operating under hovering flight conditions, i.e. where unsteady and three-dimensional rotational effects are strong, are assessed. Numerical simulations are then used to explore the role of mass and frequency ratios on aerodynamic performance, wing dynamics and flow physics. It is shown that time-averaged lift increases with frequency ratio, up to a certain limit that depends on mass ratio and beyond which upward wing bending and flexibility induced phase lag between revolving an pitching motions at stroke reversal become strong and contribute to phases of negative lift that counterbalances the initial lift increase. This wing dynamics, which is dominated by spanwise bending, also affects wing-wake interactions and, in turn, leading edge vortex formation.
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Affiliation(s)
- D Diaz-Arriba
- ISAE-Supaero, Université de Toulouse, France
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, Poitiers, France
| | - T Jardin
- ISAE-Supaero, Université de Toulouse, France
| | - N Gourdain
- ISAE-Supaero, Université de Toulouse, France
| | - F Pons
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, Poitiers, France
| | - L David
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, Poitiers, France
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Chen Z, Li T, Yang J, Zuo C. The Effect of the Swimmer's Trunk Oscillation on Dolphin Kick Performance Using a Computational Method with Multi-Body Motion: A Case Study. Int J Environ Res Public Health 2022; 19:ijerph19094969. [PMID: 35564363 PMCID: PMC9100937 DOI: 10.3390/ijerph19094969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/17/2022] [Accepted: 04/18/2022] [Indexed: 12/04/2022]
Abstract
The effect of a specific Chinese swimmer’s trunk oscillation on dolphin kick was investigated in order to optimize competitive swimming movement. Using a numerical simulation method based on multi-body motion, different swimmer’s trunk oscillation during a dolphin kick was analyzed. The simulation was conducted using 3D incompressible Navier−Stokes equations and renormalization group k-ε turbulence model, combined with the Volume of Fluid method to capture the water surface. The simulation’s results were evaluated by comparing them with experimental data and with previous studies. The net streamwise forces, mean swimming velocity, and joint moments were also investigated. There was a positive correlation between the mean swimming velocity and the amplitudes of the swimmer’s trunk oscillation, where the Pearson correlation coefficient was 0.986 and the selected model was statistically significant (p < 0.05). In addition, as the mean swimming velocity increased from 1.42 m/s in Variant 1 to 2 m/s in Variant 5, the maximum positive moments of joints increased by about 24.7% for the ankles, 27.4% for the knees, −3.9% for the hips, and 5.8% for the upper waist, whereas the maximum negative moments of joints increased by about 64.5% for the ankles, 28.1% for the knees, 23.1% for the hips, and 10.1% for the upper waist. The relationship between the trunk oscillation and the vortices was also investigated. Therefore, it is recommended that swimmers should try to increase the amplitudes of trunk oscillation to increase their swimming velocity. In order to achieve this goal, swimmers should increase strength training for the ankles, knees, and upper waist during the upkick. Moreover, extra strength training is warranted for the ankles, knees, hips, and upper waist during the downkick.
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Affiliation(s)
- Zhiya Chen
- School of Industrial Design and Ceramic Art, Foshan University, Foshan 528011, China;
| | - Tianzeng Li
- School of Industrial Design and Ceramic Art, Foshan University, Foshan 528011, China;
- Correspondence:
| | - Jin Yang
- Institute of Physical Education, Hunan University, Changsha 410082, China;
| | - Chuan Zuo
- School of Sports Science, Shanghai University of Sport, Shanghai 200438, China;
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7
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Zambrano BA, Gharahi H, Lim CY, Lee W, Baek S. Association of vortical structures and hemodynamic parameters for regional thrombus accumulation in abdominal aortic aneurysms. Int J Numer Method Biomed Eng 2022; 38:e3555. [PMID: 34859615 PMCID: PMC8858872 DOI: 10.1002/cnm.3555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/18/2021] [Accepted: 11/27/2021] [Indexed: 05/08/2023]
Abstract
The intraluminal thrombus (ILT) has been shown to negatively impact the progression of the abdominal aortic aneurysms (AAAs). The formation of this thrombus layer has been connected to the local flow environment within AAAs, but the specific mechanisms leading to thrombus formation are still not fully understood. Our study investigated the association between vortical structures, near-wall hemodynamic metrics (e.g., time averaged wall shear stress (TAWSS) and oscillatory shear index (OSI)), and ILT accumulation in a longitudinal cohort of 14 AAAs (53 scans total). Vortices and hemodynamic parameters were estimated using hemodynamic simulations performed to each scan of each patient and compared to local 3D changes of ILT thickness between two consecutive scans (ΔILT). Results showed that vortices formed and remained strong and close to the lumen surface in AAAs without an ILT, while in AAAs with ILTs these detached from the lumen surface and dissipated nearby wall region where an increase in ILT thickness was observed. Although low TAWSS was observed in regions with and without ILT accumulation, an inverse correlation between ∆ILT and TAWSS was observed within the regions that experienced a thrombus growth. Our results support the idea that vortical structures might be playing a role modulating ILT accumulation into specific wall regions. Also, it submits the idea that the low TAWSS will be modulating the growth of thrombus within these preferred ILT accumulated regions.
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Affiliation(s)
- Byron A Zambrano
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA
| | - Hamidreza Gharahi
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
| | - Chae Young Lim
- Department of Statistics, Seoul National University, Seoul, Korea
| | - Whal Lee
- Department of Radiology, Seoul National University, Seoul, Korea
| | - Seungik Baek
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
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8
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Seamone SG, Syme DA. The ocellate river stingray (Potamotrygon motoro) exploits vortices of sediment to bury into the substrate. J Fish Biol 2021; 99:1729-1734. [PMID: 34184266 DOI: 10.1111/jfb.14833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 06/13/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Particle image velocimetry and video analysis were employed to determine the pectoral-fin mechanism used by the stingray Potamotrygon motoro to bury into sand. Rapid oscillations of the body and folding motions of the posterior portion of the pectoral fin suspended sediment beneath the pectoral disc and directed vortices of sediment onto the dorsal surface, where they dissipated and the sediment settled. Body coverage was increased by increased fin displacement and speed and also by the occasional collision of vortices that redirected sediment flow towards the head and tail.
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Affiliation(s)
- Scott G Seamone
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Douglas A Syme
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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9
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Jiao WH, Xu XF, Jiang H, Xu ZA, Chen QH, Cao GH. Possible Evidence for Berezinskii-Kosterlitz-Thouless Transition in Ba(Fe 0.914Co 0.086) 2As 2 Crystals. Materials (Basel) 2021; 14:6294. [PMID: 34771819 DOI: 10.3390/ma14216294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/11/2021] [Accepted: 10/16/2021] [Indexed: 11/24/2022]
Abstract
In this study, we measure the in-plane transport properties of high-quality Ba(Fe0.914Co0.086)2As2 single crystals. Signatures of vortex unbinding Berezinskii–Kosterlitz–Thouless (BKT) transition are shown from both the conventional approach and the Fisher–Fisher–Huse dynamic scaling analysis, in which a characteristic Nelson–Kosterlitz jump is demonstrated. We also observe a non-Hall transverse signal exactly at the superconducting transition, which is explained in terms of guided motion of unbound vortices.
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Huang JC, Xiao H, Chen Z, Zheng W, Huang CC, Wu ST, Xie Z, Zhuang N. Static Retention of Dynamic Chiral Arrangements for Achiral Shear Thinning Metal-Organic Colloids. Chemistry 2021; 27:14017-14024. [PMID: 34312920 DOI: 10.1002/chem.202102068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Indexed: 11/06/2022]
Abstract
Chiral compounds are known to be important not only because they are the fundamental components of living organisms, but also for their unique chiroptical properties. In recent years, scientists have fabricated several chiral organic supramolecular aggregates by using chiral physical fields, such as vortex flow. Herein, the relationship between dynamic chiroptical properties and rheological nature is discussed, suggesting the shear thinning properties of non-Newtonian fluids might help colloidal particles adopt a chiral arrangement in vortices. Furthermore, the storage modulus of colloids could be increased by adding a linking agent, which successfully kept the dynamic chiroptical properties in the static state. Moreover, the salt effect on the host-guest interaction involved in the colloids was studied, the results suggested a significant enhancement of the transferred dynamic circular dichroism for the achiral guest molecule.
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Affiliation(s)
- Jian-Cai Huang
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China.,Fujian Science & Technology Innovation Laboratory for, Optoelectronic Information of China, Fuzhou, Fujian, 350002 (P. R., China
| | - Hui Xiao
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China.,Fujian Science & Technology Innovation Laboratory for, Optoelectronic Information of China, Fuzhou, Fujian, 350002 (P. R., China
| | - Zhixin Chen
- Fujian College Association Instrumental Analysis Center of Fuzhou University, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China
| | - Wenxu Zheng
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China
| | - Chang-Cang Huang
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China
| | - Shu-Ting Wu
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China.,Fujian Science & Technology Innovation Laboratory for, Optoelectronic Information of China, Fuzhou, Fujian, 350002 (P. R., China
| | - Zenghong Xie
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China
| | - Naifeng Zhuang
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350116, P. R. China
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Mattheck C, Greiner C, Bethge K, Tesari I, Weber K. The Force Cone Method Applied to Explain Hidden Whirls in Tribology. Materials (Basel) 2021; 14:3894. [PMID: 34300813 DOI: 10.3390/ma14143894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/09/2021] [Accepted: 07/10/2021] [Indexed: 11/16/2022]
Abstract
In tribologically loaded materials, folding instabilities and vortices lead to the formation of complex internal structures. This is true for geological as well as nanoscopic contacts. Classically, these structures have been described by Kelvin–Helmholtz instabilities or shear localization. We here introduce an alternative explanation based on an intuitive approach referred to as the force cone method. It is considered how whirls are situated near forces acting on a free surface of an elastic or elastoplastic solid. The force cone results are supplemented by finite element simulations. Depending on the direction of the acting force, one or two whirls are predicted by the simplified force cone method. In 3D, there is always a ring shaped whirl present. These modelling findings were tested in simple model experiments. The results qualitatively match the predictions and whirl formation was found. The force cone method and the experiments may seem trivial, but they are an ideal tool to intuitively understand the presence of whirls within a solid under a tribological load. The position of these whirls was found at the predicted places and the force cone method allows a direct approach to understand the complex processes in the otherwise buried interfaces of tribologically loaded materials.
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12
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Ziesen A, Hassler F. Low-energy in-gap states of vortices in superconductor-semiconductor heterostructures. J Phys Condens Matter 2021; 33:294001. [PMID: 33971638 DOI: 10.1088/1361-648x/abff93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/10/2021] [Indexed: 06/12/2023]
Abstract
The recent interest in the low-energy states in vortices of semiconductor-superconductor heterostructures are mainly fuelled by the prospects of using Majorana zero modes for quantum computation. The knowledge of low-lying states in the vortex core is essential as they pose a limitation on the topological computation with these states. Recently, the low-energy spectra of clean heterostructures, for superconducting-pairing profiles that vary slowly on the scale of the Fermi wavelength of the semiconductor, have been analytically calculated. In this work, we formulate an alternative method based on perturbation theory to obtain concise analytical formulas to predict the low-energy states including explicit magnetic-field and gap profiles. We provide results for both a topological insulator (with a linear spectrum) as well as for a conventional electron gas (with a quadratic spectrum). We discuss the spectra for a wide range of parameters, including both the size of the vortex and the chemical potential of the semiconductor, and thereby provide a tool to guide future experimental efforts. We compare these findings to numerical results.
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Affiliation(s)
- Alexander Ziesen
- JARA Institute for Quantum Information, RWTH Aachen University, Aachen, Germany
| | - Fabian Hassler
- JARA Institute for Quantum Information, RWTH Aachen University, Aachen, Germany
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13
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Lode AUJ, Dutta S, Lévêque C. Dynamics of Ultracold Bosons in Artificial Gauge Fields-Angular Momentum, Fragmentation, and the Variance of Entropy. Entropy (Basel) 2021; 23:392. [PMID: 33806185 PMCID: PMC8067171 DOI: 10.3390/e23040392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/26/2021] [Accepted: 03/11/2021] [Indexed: 11/16/2022]
Abstract
We consider the dynamics of two-dimensional interacting ultracold bosons triggered by suddenly switching on an artificial gauge field. The system is initialized in the ground state of a harmonic trapping potential. As a function of the strength of the applied artificial gauge field, we analyze the emergent dynamics by monitoring the angular momentum, the fragmentation as well as the entropy and variance of the entropy of absorption or single-shot images. We solve the underlying time-dependent many-boson Schrödinger equation using the multiconfigurational time-dependent Hartree method for indistinguishable particles (MCTDH-X). We find that the artificial gauge field implants angular momentum in the system. Fragmentation-multiple macroscopic eigenvalues of the reduced one-body density matrix-emerges in sync with the dynamics of angular momentum: the bosons in the many-body state develop non-trivial correlations. Fragmentation and angular momentum are experimentally difficult to assess; here, we demonstrate that they can be probed by statistically analyzing the variance of the image entropy of single-shot images that are the standard projective measurement of the state of ultracold atomic systems.
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Affiliation(s)
- Axel U. J. Lode
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany
| | - Sunayana Dutta
- Department of Mathematics, University of Haifa, Haifa 3498838, Israel;
- Haifa Research Center for Theoretical Physics and Astrophysics, University of Haifa, Haifa 3498838, Israel
| | - Camille Lévêque
- Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria;
- Wolfgang Pauli Institute c/o Faculty of Mathematics, University of Vienna, Oskar-Morgenstern Platz 1, 1090 Vienna, Austria
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Abstract
In 2016, the Nottingham group detected the rotational superradiance effect. While this experiment demonstrated the robustness of the superradiance process, it still lacks a complete theoretical description due to the many effects at stage in the experiment. In this paper, we shine new light on this experiment by deriving an estimate of the reflection coefficient in the dispersive regime by means of a Wentzel-Kramers-Brillouin analysis. This estimate is used to evaluate the reflection coefficient spectrum of counter-rotating modes in the Nottingham experiment. Our finding suggests that the vortex flow in the superradiance experiment was not purely absorbing, contrary to the event horizon of a rotating black hole. While this result increases the gap between this experimental vortex flow and a rotating black hole, it is argued that it is in fact this gap that is the source of novel ideas. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.
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Affiliation(s)
- Theo Torres
- Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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15
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Lillie SE, Broadway DA, Dontschuk N, Scholten SC, Johnson BC, Wolf S, Rachel S, Hollenberg LCL, Tetienne JP. Laser Modulation of Superconductivity in a Cryogenic Wide-field Nitrogen-Vacancy Microscope. Nano Lett 2020; 20:1855-1861. [PMID: 32017577 DOI: 10.1021/acs.nanolett.9b05071] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We realize a cryogenic wide-field nitrogen-vacancy microscope and use it to image Abrikosov vortices and transport currents in a superconducting Nb film. We observe the disappearance of vortices upon increase of laser power and their clustering about hot spots upon decrease, indicating local quenching of superconductivity by the laser. Resistance measurements confirm the presence of large temperature gradients across the film. We then investigate the effect of such gradients on transport currents where the current path is seen to correlate with the temperature profile even in the fully superconducting phase. In addition to highlighting the role of temperature inhomogeneities in superconductivity phenomena, this work establishes that under sufficiently low laser power conditions wide-field nitrogen-vacancy microscopy enables imaging over mesoscopic scales down to 4 K with submicrometer spatial resolution, providing a new platform for spatially resolved investigations of a range of systems from topological insulators to van der Waals ferromagnets.
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Affiliation(s)
- Scott E Lillie
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - David A Broadway
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Nikolai Dontschuk
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Sam C Scholten
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Brett C Johnson
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Sebastian Wolf
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Stephan Rachel
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Lloyd C L Hollenberg
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC 3010, Australia
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16
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Krueger PS, Hahsler M, Olinick EV, Williams SH, Zharfa M. Quantitative classification of vortical flows based on topological features using graph matching. Proc Math Phys Eng Sci 2019; 475:20180897. [PMID: 31534418 DOI: 10.1098/rspa.2018.0897] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 07/10/2019] [Indexed: 11/12/2022] Open
Abstract
Vortical flow patterns generated by swimming animals or flow separation (e.g. behind bluff objects such as cylinders) provide important insight to global flow behaviour such as fluid dynamic drag or propulsive performance. The present work introduces a new method for quantitatively comparing and classifying flow fields using a novel graph-theoretic concept, called a weighted Gabriel graph, that employs critical points of the velocity vector field, which identify key flow features such as vortices, as graph vertices. The edges (connections between vertices) and edge weights of the weighted Gabriel graph encode local geometric structure. The resulting graph exhibits robustness to minor changes in the flow fields. Dissimilarity between flow fields is quantified by finding the best match (minimum difference) in weights of matched graph edges under relevant constraints on the properties of the edge vertices, and flows are classified using hierarchical clustering based on computed dissimilarity. Application of this approach to a set of artificially generated, periodic vortical flows demonstrates high classification accuracy, even for large perturbations, and insensitivity to scale variations and number of periods in the periodic flow pattern. The generality of the approach allows for comparison of flows generated by very different means (e.g. different animal species).
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Affiliation(s)
- Paul S Krueger
- Department of Mechanical Engineering, Information, and Systems, Southern Methodist University, Dallas, TX 75275, USA
| | - Michael Hahsler
- Department of Engineering Management, Information, and Systems, Southern Methodist University, Dallas, TX 75275, USA
| | - Eli V Olinick
- Department of Engineering Management, Information, and Systems, Southern Methodist University, Dallas, TX 75275, USA
| | - Sheila H Williams
- Department of Mechanical Engineering, Information, and Systems, Southern Methodist University, Dallas, TX 75275, USA
| | - Mohammadreza Zharfa
- Department of Mechanical Engineering, Information, and Systems, Southern Methodist University, Dallas, TX 75275, USA
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Abstract
The aim of this study was to provide a fundamental understanding of how the hands create swim propulsion by applying Newton's Laws to observations of the behaviour of water in simple demonstrations. Using a video recorder, we captured a series of straight and curved pulls made near and under the pool surface. The pulls were performed using a plastic disc or a human hand/arm. Videos from the demonstrations showed that masses of water accelerate from the dorsal side of the hand/plastic disc, and in a straight pull, generates a reaction force moving the body forward, consistent with Newton's Laws. Demonstrations conducted on the curvilinear pull indicated that changes in the pull direction result in an interaction with the water to accelerate water backwards to generate a force thrusting the body forward.
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Affiliation(s)
| | - Ross Sanders
- Faculty of Health Sciences, The University of Sydney, Exercise and Sport Science, Cumberland Campus, Sydney, Australia
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18
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Abstract
We have performed device-based tunneling spectroscopy of NbSe2 in the vortex state with a magnetic field applied both parallel and perpendicular to the a- b plane. Our devices consist of layered semiconductors placed on top of exfoliated NbSe2 using the van der Waals transfer technique. At zero field, the spectrum exhibits a hard gap, and the quasiparticle peak is split into low- and high-energy features. The two features, associated with the effective two-band nature of superconductivity in NbSe2, exhibit markedly distinct responses to the application of magnetic field, suggesting an order-of-magnitude difference in the spatial extent of the vortex cores of the two bands. At energies below the superconducting gap, the hard gap gives way to vortex-bound Caroli-de Gennes-Matricon states, allowing the detection of individual vortices as they enter and exit the junction. Analysis of the subgap spectra upon application of parallel magnetic field allows us to track the process of vortex surface formation and spatial rearrangement in the bulk.
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Affiliation(s)
- Tom Dvir
- The Racah Institute of Physics , The Hebrew University of Jerusalem , Givat Ram , Jerusalem 91904 , Israel
| | - Marco Aprili
- Laboratoire de Physique des Solides (CNRS UMR 8502) , Btiment 510, Universit Paris-Sud/Université Paris-Saclay , 91405 Orsay , France
| | - Charis H L Quay
- Laboratoire de Physique des Solides (CNRS UMR 8502) , Btiment 510, Universit Paris-Sud/Université Paris-Saclay , 91405 Orsay , France
| | - Hadar Steinberg
- The Racah Institute of Physics , The Hebrew University of Jerusalem , Givat Ram , Jerusalem 91904 , Israel
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Geng W, Guo X, Zhu Y, Tang Y, Feng Y, Zou M, Wang Y, Han M, Ma J, Wu B, Hu W, Ma X. Rhombohedral-Orthorhombic Ferroelectric Morphotropic Phase Boundary Associated with a Polar Vortex in BiFeO 3 Films. ACS Nano 2018; 12:11098-11105. [PMID: 30352155 DOI: 10.1021/acsnano.8b05449] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Strongly correlated oxides exhibit multiple degrees of freedoms, which can potentially mediate exotic phases with exciting physical properties, such as the polar vortex recently found in ferroelectric oxide films. A polar vortex is stabilized by competition between charge, lattice, and/or orbital degrees of freedom, which displays vortex-ferroelectric phase transitions and emergent chirality, making it a potential candidate for designing information storage and processing devices. Here, by a combination of controlled film growth and aberration-corrected scanning transmission electron microscopy, we obtain nanoscale vortex arrays in [110]-oriented BiFeO3 films. These vortex arrays are stabilized in ultrathin BiFeO3 layers sandwiched by two coherently grown orthorhombic scandate layers, exhibiting a ferroelectric morphotropic phase boundary constituted by a mixed-phase structure of polar orthorhombic BiFeO3 and rhombohedral BiFeO3. Clear polarization switching and piezoelectric signals were observed in these multilayers as revealed by piezoresponse force microscopy. This work presents a feature of a polar vortex in BiFeO3 films showing morphotropic phase boundary character, which offers a potential degree of manipulating phase components and properties of ferroelectric topological structures.
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Affiliation(s)
- Wanrong Geng
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Science and Technology of China , Jinzhai Road 96 , 230026 Hefei , China
| | - Xiangwei Guo
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Science and Technology of China , Jinzhai Road 96 , 230026 Hefei , China
| | - Yinlian Zhu
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
| | - Yunlong Tang
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
| | - Yanpeng Feng
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Chinese Academy of Sciences , Yuquan Road 19 , 100049 Beijing , China
| | - Minjie Zou
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Science and Technology of China , Jinzhai Road 96 , 230026 Hefei , China
| | - Yujia Wang
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
| | - Mengjiao Han
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Chinese Academy of Sciences , Yuquan Road 19 , 100049 Beijing , China
| | - Jinyuan Ma
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Science and Technology of China , Jinzhai Road 96 , 230026 Hefei , China
- State Key Lab of Advanced Processing and Recycling on Non-ferrous Metals , Lanzhou University of Technology , Langongping Road 287 , 730050 Lanzhou , China
| | - Bo Wu
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Science and Technology of China , Jinzhai Road 96 , 230026 Hefei , China
| | - Wentao Hu
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- University of Science and Technology of China , Jinzhai Road 96 , 230026 Hefei , China
| | - Xiuliang Ma
- Shenyang National Laboratory for Materials Science , Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72 , 110016 Shenyang , China
- State Key Lab of Advanced Processing and Recycling on Non-ferrous Metals , Lanzhou University of Technology , Langongping Road 287 , 730050 Lanzhou , China
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20
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Veretenov NA, Fedorov SV, Rosanov NN. Topological three-dimensional dissipative optical solitons. Philos Trans A Math Phys Eng Sci 2018; 376:rsta.2017.0367. [PMID: 29891495 PMCID: PMC6000154 DOI: 10.1098/rsta.2017.0367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/17/2018] [Indexed: 05/20/2023]
Abstract
This article presents a review of recent investigations of topological three-dimensional (3D) dissipative optical solitons in homogeneous laser media with fast nonlinearity of amplification and absorption. The solitons are found numerically, with their formation, by embedding two-dimensional laser solitons or their complexes in 3D space after their rotation around a vortex straight line with their simultaneous twist. After a transient, the 'hula-hoop' solitons can form with a number of closed and unclosed infinite vortex lines, i.e. the solitons are tangles in topological notation. They are attractors and are characterized by extreme stability. The solitons presented here can be realized in lasers with fast saturable absorption and are promising for information applications. The tangle solitons of the type described present an example of self-organization that can be found not only in optics but also in various distributed dissipative systems of different types.This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 1)'.
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Affiliation(s)
- N A Veretenov
- Vavilov State Optical Institute, Theoretical Department, St. Petersburg, Russia
- ITMO University, Institute of Photonics and Optoinformatics, St. Petersburg, Russia
| | - S V Fedorov
- ITMO University, Institute of Photonics and Optoinformatics, St. Petersburg, Russia
| | - N N Rosanov
- Vavilov State Optical Institute, Theoretical Department, St. Petersburg, Russia
- ITMO University, Institute of Photonics and Optoinformatics, St. Petersburg, Russia
- Ioffe Institute, Laboratory of Atomic Radiospectroscopy, St. Petersburg, Russia
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Zhang J, Luo X. Mixing Performance of a 3D Micro T-Mixer with Swirl-Inducing Inlets and Rectangular Constriction. Micromachines (Basel) 2018; 9:E199. [PMID: 30424132 PMCID: PMC6187579 DOI: 10.3390/mi9050199] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 11/16/2022]
Abstract
In this paper, three novel 3D micro T-mixers, namely, a micro T-mixer with swirl-inducing inlets (TMSI), a micro T-mixer with a rectangular constriction (TMRC), and a micro T-mixer with swirl-inducing inlets and a rectangular constriction (TMSC), were proposed on the basis of the original 3D micro T-mixer (OTM). The flow and mixing performance of these micromixers was numerically analyzed using COMSOL Multiphysics package at a range of Reynolds numbers from 10 to 70. Results show that the three proposed 3D micro T-mixers have achieved better mixing performance than OTM. Due to the coupling effect of two swirl-inducing inlets and a rectangular constriction, the maximum mixing index and pressure drop appeared in TMSC among the four micromixers especially; the mixing index of TMSC reaches 91.8% at Re = 70, indicating that TMSC can achieve effective mixing in a short channel length, but has a slightly higher pressure drop than TMSI and TMRC.
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Affiliation(s)
- Jinxin Zhang
- School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China.
| | - Xiaoping Luo
- School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China.
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22
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Feng W, Stanislavova M. On the vortices for the nonlinear Schrödinger equation in higher dimensions. Philos Trans A Math Phys Eng Sci 2018; 376:rsta.2017.0189. [PMID: 29507174 PMCID: PMC5869610 DOI: 10.1098/rsta.2017.0189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/05/2018] [Indexed: 06/08/2023]
Abstract
We consider the nonlinear Schrödinger equation in n space dimensions [Formula: see text]and study the existence and stability of standing wave solutions of the form [Formula: see text]and [Formula: see text]For n=2k, (rj ,θj ) are polar coordinates in [Formula: see text], j=1,2,…,k; for n=2k+1, (rj ,θj ) are polar coordinates in [Formula: see text], (rk ,θk ,z) are cylindrical coordinates in [Formula: see text], j=1,2,…,k-1. We show the existence of functions ϕw , which are constructed variationally as minimizers of appropriate constrained functionals. These waves are shown to be spectrally stable (with respect to perturbations of the same type), if 1<p<1+4/nThis article is part of the theme issue 'Stability of nonlinear waves and patterns and related topics'.
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Affiliation(s)
- Wen Feng
- Department of Mathematics, University of Kansas, 1460 Jayhawk Boulevard, Lawrence, KS 66045-7523, USA
| | - Milena Stanislavova
- Department of Mathematics, University of Kansas, 1460 Jayhawk Boulevard, Lawrence, KS 66045-7523, USA
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23
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Abstract
We present a detailed analysis of the interaction between two nanocrystals capped with ligands consisting of hydrocarbon chains by united atom molecular dynamics simulations. We show that the bonding of two nanocrystals is characterized by ligand textures in the form of vortices. These results are generalized to nanocrystals of different types (differing core and ligand sizes) where the structure of the vortices depends on the softness asymmetry. We provide rigorous calculations for the binding free energy, show that these energies are independent of the chemical composition of the cores, and derive analytical formulas for the equilibrium separation. We discuss the implications of our results for the self-assembly of single-component and binary nanoparticle superlattices. Overall, our results show that the structure of the ligands completely determines the bonding of nanocrystals, fully supporting the predictions of the recently proposed Orbifold topological model.
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Affiliation(s)
- Curt Waltmann
- Department of Materials Science and Engineering and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
| | - Nathan Horst
- Department of Materials Science and Engineering and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
| | - Alex Travesset
- Department of Materials Science and Engineering and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
- Department of Physics and Astronomy and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
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Abstract
Fishes often live in environments characterized by complex flows. To study the mechanisms of how fishes interact with unsteady flows, the periodic shedding of vortices behind cylinders has been employed to great effect. In particular, fishes that hold station in a vortex street (i.e., Kármán gaiting) show swimming kinematics that are distinct from their patterns of motion during freestream swimming in uniform flows, although both behaviors can be modeled as an undulatory body wave. Kármán gait kinematics are largely preserved across flow velocities. Larger fish have a shorter body wavelength and slower body wave speed than smaller fish, in contrast to freestream swimming where body wavelength and wave speed increases with size. The opportunity for Kármán gaiting only occurs under specific conditions of flow velocity and depends on the length of the fish; this is reflected in the highest probability of Kármán gaiting at intermediate flow velocities. Fish typically Kármán gait in a region of the cylinder wake where the velocity deficit is about 40% of the nominal flow. The lateral line plays a role in tuning the kinematics of the Kármán gait, since blocking it leads to aberrant kinematics. Vision allows fish to maintain a consistent position relative to the cylinder. In the dark, fish do not show the same preference to hold station behind a cylinder though Kármán gait kinematics are the same. When oxygen consumption level is measured, it reveals that Kármán gaiting represents about half of the cost of swimming in the freestream.
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Affiliation(s)
- James C Liao
- The Whitney Laboratory for Marine Bioscience, Department of Biology, University of Florida
| | - Otar Akanyeti
- Department of Computer Science, Aberystwyth University
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25
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Abstract
Microtubules (MTs) are protein filaments that provide structure to the cytoskeleton of cells and a platform for the movement of intracellular substances. The spatial organization of MTs is crucial for a cell's form and function. MTs interact with a class of proteins called motor proteins that can transport and position individual filaments, thus contributing to overall organization. In this paper, we study the mathematical properties of a coupled partial differential equation (PDE) model, introduced by White et al. in 2015, that describes the motor-induced organization of MTs. The model consists of a nonlinear coupling of a hyperbolic PDE for bound motor proteins, a parabolic PDE for unbound motor proteins, and a transport equation for MT dynamics. We locally smooth the motor drift velocity in the equation for bound motor proteins. The mollification is not only critical for the analysis of the model, but also adds biological realism. We then use a Banach Fixed Point argument to show local existence and uniqueness of mild solutions. We highlight the applicability of the model by showing numerical simulations that are consistent with in vitro experiments.
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Affiliation(s)
- Thomas Hillen
- a Department of Mathematical and Statistical Sciences , Centre for Mathematical Biology, University of Alberta , Edmonton , AB , Canada
| | - Diana White
- b Aix-Marseille University, Institute of Mathematics , Marseille , France
| | - Gerda de Vries
- a Department of Mathematical and Statistical Sciences , Centre for Mathematical Biology, University of Alberta , Edmonton , AB , Canada
| | - Adriana Dawes
- c Department of Mathematics , Ohio State University , Columbus , OH , USA
- d Department of Molecular Genetics , Ohio State University , Columbus , OH , USA
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Abstract
A number of bewildering paradoxes arise in the field of nanoparticle self-assembly: nominal low density superlattices, strong stability of low coordination sites, and a clear but imperfect correlation between lattice stability and the maximum of hard sphere packing, despite the fact that that nanocrystals themselves are, through their ligands, very much compressible. In this study, I show that by regarding nanocrystals as pseudotopological objects ("soft skyrmions"), it is possible to identify and classify the ligand textures that determine their bonding. These textures consist of interacting vortices, where the total vorticity defines a spontaneous valence (coordination). Furthermore, skyrmion interactions are governed by two simple assumptions, which lead to a set of selection rules for superlattice structure. Besides resolving all the above paradoxes, the predictions are completely supported by more than one hundred sixty experiments gathered from the literature, including a wide range of nanocrystal cores and ligands (saturated or unsaturated hydrocarbons, amines, polystyrene, etc.). How those results can be used for addressing more complex structures and guiding future experiments is also addressed.
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Affiliation(s)
- Alex Travesset
- Department of Physics and Astronomy and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
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Rey-Martinez J, McGarvie L, Pérez-Fernández N. Computing simulated endolymphatic flow thermodynamics during the caloric test using normal and hydropic duct models. Acta Otolaryngol 2017; 137:270-274. [PMID: 27739351 DOI: 10.1080/00016489.2016.1242775] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
CONCLUSION The obtained simulations support the underlying hypothesis that the hydrostatic caloric drive is dissipated by local convective flow in a hydropic duct. OBJECTIVE To develop a computerized model to simulate and predict the internal fluid thermodynamic behavior within both normal and hydropic horizontal ducts. METHODS This study used a computational fluid dynamics software to simulate the effects of cooling and warming of two geometrical models representing normal and hydropic ducts of one semicircular horizontal canal during 120 s. RESULTS Temperature maps, vorticity, and velocity fields were successfully obtained to characterize the endolymphatic flow during the caloric test in the developed models. In the normal semicircular canal, a well-defined endolymphatic linear flow was obtained, this flow has an opposite direction depending only on the cooling or warming condition of the simulation. For the hydropic model a non-effective endolymphatic flow was predicted; in this model the velocity and vorticity fields show a non-linear flow, with some vortices formed inside the hydropic duct.
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Jemmett-Smith BC, Marsham JH, Knippertz P, Gilkeson CA. Quantifying global dust devil occurrence from meteorological analyses. Geophys Res Lett 2015; 42:1275-1282. [PMID: 26681815 PMCID: PMC4670712 DOI: 10.1002/2015gl063078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 01/28/2015] [Indexed: 06/05/2023]
Abstract
UNLABELLED Dust devils and nonrotating dusty plumes are effective uplift mechanisms for fine particles, but their contribution to the global dust budget is uncertain. By applying known bulk thermodynamic criteria to European Centre for Medium-Range Weather Forecasts (ECMWF) operational analyses, we provide the first global hourly climatology of potential dust devil and dusty plume (PDDP) occurrence. In agreement with observations, activity is highest from late morning into the afternoon. Combining PDDP frequencies with dust source maps and typical emission values gives the best estimate of global contributions of 3.4% (uncertainty 0.9-31%), 1 order of magnitude lower than the only estimate previously published. Total global hours of dust uplift by dry convection are ∼0.002% of the dust-lifting winds resolved by ECMWF, consistent with dry convection making a small contribution to global uplift. Reducing uncertainty requires better knowledge of factors controlling PDDP occurrence, source regions, and dust fluxes induced by dry convection. KEY POINTS Global potential dust devil occurrence quantified from meteorological analyses Climatology shows realistic diurnal cycle and geographical distribution Best estimate of global contribution of 3.4% is 10 times smaller than the previous estimate.
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Affiliation(s)
- Bradley C Jemmett-Smith
- Institute for Climate and Atmospheric Science, School of Earth and Environment, University of LeedsLeeds, UK
| | - John H Marsham
- Institute for Climate and Atmospheric Science, School of Earth and Environment, University of LeedsLeeds, UK
- National Centre for Atmospheric ScienceLeeds, UK
| | - Peter Knippertz
- Institute for Meteorology and Climate Research, Karlsruhe Institute of TechnologyKarlsruhe, Germany
| | - Carl A Gilkeson
- Institute of Thermofluids, School of Mechanical Engineering, University of LeedsLeeds, UK
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Khosla S, Oren L, Ying J, Gutmark E. Direct simultaneous measurement of intraglottal geometry and velocity fields in excised larynges. Laryngoscope 2014; 124 Suppl 2:S1-13. [PMID: 24510612 DOI: 10.1002/lary.24512] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Accepted: 11/04/2013] [Indexed: 11/09/2022]
Abstract
OBJECTIVES/HYPOTHESIS Current theories regarding the mechanisms of phonation are based on assumptions about the aerodynamics between the vocal folds during the closing phase of vocal fold vibration. However, many of these fundamental assumptions have never been validated in a tissue model. In this study, the main objective was to determine the aerodynamics (velocity fields) and the geometry of the medial surface of the vocal folds during the closing phase of vibration. The main hypothesis is that intraglottal vortices are produced during vocal fold closing when the glottal duct has a divergent shape and that these vortices are associated with negative pressures. STUDY DESIGN Experiments using seven excised canine larynges. METHODS The particle imaging velocimetry (PIV) method was used to determine the velocity fields at low, mid-, and high subglottal pressures for each larynx. Modifications were made to previously described PIV methodology to allow the measurement of both the intraglottal velocity fields and the position of the medial aspects of the vocal fold. RESULTS At relatively low subglottal pressures, little to no intraglottal vortices were seen. At mid- and high subglottal pressures, the flow separation vortices occurred and produced maximum negative pressures, relative to atmospheric, of -2.6 to -14.6 cm H2 O. Possible physiological and surgical implications are discussed. CONCLUSIONS Intraglottal vortices produce significant negative pressures at mid- and high subglottal pressures. These vortices may be important in increasing maximum flow declination rate and acoustic intensity. LEVEL OF EVIDENCE N/A.
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Affiliation(s)
- Sid Khosla
- Department of Otolaryngology/Head & Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, U.S.A
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30
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Abstract
In order to understand the physical mechanisms of the production of nanometer-sized particulate generated from cooking oils, the ventilation of kitchen hoods was studied by determining the particle concentration, particle size distribution, particle dimensions, and hood's flow characteristics under several cooking scenarios. This research varied the temperature of the frying operation on one cooking operation, with three kinds of commercial cooking oils including soybean oil, olive oil, and sunflower oil. The variations of particle concentration and size distributions with the elevated cooking oil temperatures were presented. The particle concentration increases as a function of temperature. For oil temperatures ranging between 180°C and 210°C, a 5°C increase in temperature increased the number concentration of ultrafine particles by 20-50%. The maximum concentration of ultrafine particles was found to be approximately 6 × 10(6) particles per cm(3) at 260°C. Flow visualization techniques and particle distribution measurement were performed for two types of hood designs, a wall-mounted range hood and an island hood, at a suction flow rate of 15 m(3) min(-1). The flow visualization results showed that different configurations of kitchen hoods induce different aerodynamic characteristics. By comparing the results of flow visualizations and nanoparticle measurements, it was found that the areas with large-scale turbulent vortices are more prone to dispersion of ultrafine particle leakage because of the complex interaction between the shear layers and the suction movement that results from turbulent dispersion. We conclude that the evolution of ultrafine particle concentration fluctuations is strongly affected by the location of the hood, which can alter the aerodynamic features. We suggest that there is a correlation between flow characteristics and amount of contaminant leakage. This provides a comprehensive strategy to evaluate the effectiveness of kitchen hoods in capturing cooking oil fumes, which is based on an assessment of the entire hood face exposure instead of on breathing-zone sampling alone.
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Affiliation(s)
- Li-Ching Tseng
- Institute of Occupational Medicine and Industrial Hygiene, National Yang Ming University, Taipei, Taiwan.
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