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Repulsion-attraction switching of nematic colloids formed by liquid crystal dispersions of polygonal prisms

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arXiv 2017年

作者： Senyuk, B. Liu, Q. Nystrom, P.D. Smalyukh, I.I. Dept. of Physics and Soft Materials Research Center Univ. of Colorado at Boulder BoulderCO80309 United States Materials Science and Engineering Program Univ. of Colorado at Boulder BoulderCO80309 United States Dept. of Electrical Computer and Energy Engineering Univ. of Colorado at Boulder BoulderCO80309 United States Renewable and Sustainable Energy Institute National Renewable Energy Laboratory Univ. of Colorado at Boulder BoulderCO80309 United States

Self-assembly of colloidal particles due to elastic interactions in nematic liquid crystals promises tunable composite materials and can be guided by exploiting surface functionalization, geometric shape and topology, though these means of controlling self-assembly remain limited. Here, we realize low-symmetry achiral and chiral elastic colloids in the nematic liquid crystals using colloidal polygonal concave and convex prisms. We show that the controlled pinning of disclinations at the prisms edges alters the symmetry of director distortions around the prisms and their orientation with respect to the far-field director. The controlled localization of the disclinations at the prism's edges significantly influences anisotropy of the diffusion properties of prisms dispersed in liquid crystals and allows one to modify their self-assembly. We show that elastic interactions between polygonal prisms can be switched between repulsive and attractive just by controlled re-pinning the disclinations at different edges using laser tweezers. Our findings demonstrate that elastic interactions between colloidal particles dispersed in nematic liquid crystals are sensitive to the topologically equivalent but geometrically rich controlled configurations of the particle-induced defects. Copyright © 2017, The Authors. All rights reserved.

关键词： Topology

Erratum: “Growth and characterization of β-Ga2O3 thin films by molecular beam epitaxy for deep-UV photodetectors” [J. Appl. Phys. 122, 095302 (2017)]

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Journal of Applied Physics 2018年第13期124卷

作者： Susmita Ghose Shafiqur Rahman Liang Hong Juan Salvador Rojas-Ramirez Hanbyul Jin Kibog Park Robert Klie Ravi Droopad 1Material Science Engineering and Commercialization Program Texas State University San Marcos Texas 78666 USA 2Department of Physics University of Illinois at Chicago Chicago Illinois 60607 USA 3Ingram School of Engineering Texas State University San Marcos Texas 78666 USA 4School of Electrical and Computer Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 South Korea 5Department of Physics Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 South Korea

We noticed an omission of the acknowledgment and provide it here with apologies:1

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Tuning and switching a plasmonic quantum dot 'sandwich' in a nematic line defect

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arXiv 2017年

作者： Mundoor, Haridas Sheetah, Ghadah Park, Sungoh Ackerman, Paul J. Smalyukh, Ivan I. Van De Lagemaat, Jao Department of Physics University of Colorado BoulderCO80309 United States Materials Science and Engineering Program University of Colorado BoulderCO80309 United States Soft Materials Research Center Department of Electrical Computer and Energy Engineering University of Colorado BoulderCO80309 United States Renewable and Sustainable Energy Institute National Renewable Energy Laboratory University of Colorado BoulderCO80309 United States National Renewable Energy Laboratory GoldenCO80401 United States

We study the quantum-mechanical effects arising in a single semiconductor core/shell quantum dot controllably sandwiched between two plasmonic nanorods. Control over the position and the "sandwich" confinement structure is achieved by the use of a linear-trap, liquid-crystal line defect and laser tweezers that 'push' the sandwich together. This arrangement allows for the study of exciton-plasmon interactions in a single structure, unaltered by ensemble effects or the complexity of dielectric interfaces. We demonstrate the effect of plasmonic confinement on the photonantibunching behavior of the quantum dot and its luminescence lifetime. The quantum dot behaves as a single emitter when nanorods are far away from the quantum dot but shows possible multiexciton emission and a significantly decreased lifetime when tightly confined in a plasmonic 'sandwich'. These findings demonstrate that liquid crystal defects, combined with laser tweezers, enable a versatile platform to study plasmonic coupling phenomena in a nanoscale laboratory, where all elements can be arranged almost at will. Copyright © 2017, The Authors. All rights reserved.

关键词： Semiconductor quantum dots

Impact of carrier localization on recombination in InGaN quantum wells and the efficiency of nitride light-emitting diodes: Insights from theory and numerical simulations

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arXiv 2017年

作者： Jones, Christina M. Teng, Chu-Hsiang Yan, Qimin Ku, Pei-Cheng Kioupakis, Emmanouil Applied Physics Program University of Michigan 450 Church St Ann ArborMI48109 United States Electrical Engineering and Computer Science Department University of Michigan 1301 Beal Ave Ann ArborMI48109 United States Department of Physics Temple University 1925 N. 12th St PhiladelphiaPA19122 United States Materials Science and Engineering Department University of Michigan 2300 Hayward St Ann ArborMI48109 United States

We examine the effect of carrier localization due to random alloy fluctuations on the radiative and Auger recombination rates in InGaN quantum wells as a function of alloy composition, crystal orientation, carrier density, and temperature. Our results show that alloy fluctuations reduce individual transition matrix elements by the separate localization of electrons and holes, but this effect is overcompensated by the additional transitions enabled by translational symmetry breaking and the resulting lack of momentum conservation. Hence, we find that localization increases both radiative and Auger recombination rates, but that Auger recombination rates increase by one order of magnitude more than radiative rates. Furthermore, we demonstrate that localization has an overall detrimental effect on the efficiency-droop and green-gap problems of InGaN LEDs. Copyright © 2017, The Authors. All rights reserved.

关键词： Crystal orientation

Choreographic and somatic approaches for the development of expressive robotic systems

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arXiv 2017年

作者： LaViers, Amy Cuan, Catie Heimerdinger, Madison Huzaifa, Umer Maguire, Catherine McNish, Reika Nilles, Alexandra Pakrasi, Ishaan Bradley, Karen Mata, Kim Brooks Chakraborty, Novoneel Vidrin, Ilya Zurawski, Alexander Mechanical Science and Engineering Department University of Illinois Urbana-Champaign United States Aerospace Engineering Department University of Illinois Urbana-Champaign United States Laban/Bartenieff Institute of Movement Studies Kinesiology and Community Health Department University of Illinois Urbana-Champaign United States Computer Science Department University of Illinois Urbana-Champaign United States Dance Program University of Virginia Integrated Movement Studies Centre for Dance Research Coventry University Department of Theatre Dance and Media Harvard University

As robotic systems are moved out of factory work cells into human-facing environments questions of choreography become central to their design, placement, and application. With a human viewer or counterpart present, a system will automatically be interpreted within context, style of movement, and form factor by human beings as animate elements of their environment. The interpretation by this human counterpart is critical to the success of the system’s integration: "knobs" on the system need to make sense to a human counterpart;an artificial agent should have a way of notifying a human counterpart of a change in system state, possibly through motion profiles;and the motion of a human counterpart may have important contextual clues for task completion. Thus, professional choreographers, dance practitioners, and movement analysts are critical to research in robotics. They have design methods for movement that align with human audience perception;they can help identify simplified features of movement that will effectively accomplish human-robot interaction goals;and they have detailed knowledge of the capacity of human movement. This article provides approaches employed by one research lab, specific impacts on technical and artistic projects within, and principles that may guide future such work. The background section reports on choreography, somatic perspectives, improvisation, the Laban/Bartenieff Movement System, and robotics. From this context methods including embodied exercises, writing prompts, and community building activities have been developed to facilitate interdisciplinary research. The results of this work is presented as an overview of a smattering of projects in areas like high-level motion planning, software development for rapid prototyping of movement, artistic output, and user studies that help understand how people interpret movement. Finally, guiding principles for other groups to adopt are posited. Copyright © 2017, The Authors. All rights reserv

关键词： Robotics

Plasmon-Exciton interactions probed using spatial coentrapment of nanoparticles by topological singularities

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arXiv 2017年

作者： Ackerman, P.J. Mundoor, Haridas Smalyukh, I.I. Lagemaat, Jao Vande Department of Physics University of Colorado BoulderCO80309 United States Department of Electrical Computer and Energy Engineering University of Colorado BoulderCO80309 United States Liquid Crystal Materials Research Center and Materials Science and Engineering Program University of Colorado BoulderCO80309 United States Renewable and Sustainable Energy Institute National Renewable Energy Laboratory University of Colorado BoulderCO80309 United States National Renewable Energy Laboratory GoldenCO80401 United States

We study *** interaction by using topological singularities to spatially confine, selectively deliver, cotrap and optically probe colloidal semiconductor and plasmonic nanoparticles. The interaction is monitored in a single quantum system in the bulk of a liquid crystal medium where nanoparticles are manipulated and nanoconfined far from dielectric interfaces using laser tweezers and topological configurations containing singularities. When quantum dot-in-a-rod particles are spatially colocated with a plasmonic gold nanoburst par-ticle in a topological singularity core, its uorescence in-creases because blinking is significantly suppressed and the radiative decay rate increases by nearly an order of magni-tude owing to the Purcell effect. We argue that the blinking suppression is the result of the radiative rate change that mitigates Auger recombination and quantum dot ionization, consequently reducing nonradiative recombination. Our work demonstrates that topological singularities are an effec-tive platform for studying and controlling *** interactions. Copyright © 2017, The Authors. All rights reserved.

关键词： Semiconductor quantum dots

Authenticated secret sharing scheme based on GMEMD

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Lecture Notes in Computer Science (including subseries Lectu...

Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2016年 9569卷 395-405页

作者： Kuo, Wen-Chung Kuo, Shao-Hung Chang, Hong-Yi Wuu, Lih-Chyau Department of Computer Science and Information Engineering National Yunlin University of Science and Technology Douliu Taiwan Graduate School of Engineering Science and Technology Doctoral Program National Yunlin University of Science and Technology Douliu Taiwan

ISBN: (纸本)9783319319599

In secret image sharing schemes, all legal participants provide legitimate shared images and then they can extract the correct secret message. Recently, Wu et al. proposed a high quality data hiding secret sharing scheme with authentication ability. The major contribution of this scheme maintains good stego image quality while being able to verify secret message integrity. However, to ensure the process can work, the secret image’s pixel values larger than 250 must be changed to 250 for Wu’s scheme. Otherwise, extracting the secret image may fail. In other words, for a secret image, a few errors do not make the big difference but it could be distorted severely for some sensitive secrets. In order to improve this shortcoming, a secret image sharing scheme based on General Multi-Exploiting Modification Direction (GMEMD) data hiding technology will be proposed in this paper. According to simulation results and analysis, we can show that the stego image quality in Wu et al.’s scheme or our proposed scheme is larger than 43dB. We also demonstrate the authentication capability to find unauthorized participants. Furthermore, if all participants are legitimate, then the proposed scheme can extract the secret completely without any distortion. © Springer International Publishing Switzerland 2016.

关键词： Authentication

An Energy Efficient Hybrid Clustering Routing Protocol for Underwater WSNs

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An Energy Efficient Hybrid Clustering Routing Protocol for U...

International Workshop on Bio and Intelligent Computing

作者： Mudassir Ejaz Nadeem Javaid Hammad Maqsood Usman Shakeel Zahoor Ali Khan Umar Qasim Department of Computer Science COMSATS Institute of Information Technology Internetworking Program Faculty of Engineering Dalhousie University Cameron Library University of Alberta

ISBN: (纸本)9781509024629

Underwater acoustic communications are a hastily growing field of research and engineering, which once were exclusively for military applications are now extending into commercial fields. Underwater Wireless Sensor Networks (UWSNs) appeal the research community, facing challenges as sensor nodes have energy constraint and radio signals are not suitable for underwater wireless communication. This paper explores an Energy Efficient Hybrid Clustering routing protocol (EEHC) for UWSNs, depicted from Depth-Based Energy-Balanced Hybrid (DB-EBH) routing protocol with integrated clustering technique.

关键词： Acoustic Communication Underwater Wireless Sensor Networks (UWSNs) Energy Efficient Hybrid Clustering (EEHC) Depth-Based Energy-Balanced Hybrid (DB-EBH)

Exploring low internal reorganization energies for silicene nanoclusters

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arXiv 2017年

作者： Pablo-Pedro, Ricardo Lopez-Rios, Hector Mendoza-Cortes, Jose-L Kong, Jing Fomine, Serguei van Voorhis, Troy Dresselhaus, Mildred S. Department of Chemistry Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Instituto de Investigaciones en Materiales Universidad Nacional Autónoma de México Apartado Postal 70-360 CU Coyoacán Ciudad de México04510 Mexico Department of Chemical & Biomedical Engineering Florida A&M University Florida State University Joint College of Engineering Tallahassee FL32310 United States Scientific Computing Department Materials Science and Engineering Program High Performance Material Institute Condensed Matter Theory National High Magnetic Field Laboratory Florida State University TallahasseeFL32310 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States

High-performance materials rely on small reorganization energies to facilitate both charge separation and charge transport. Here, we performed DFT calculations to predict small reorganization energies of rectangular silicene nanoclusters with hydrogen-passivated edges denoted by H-SiNC. We observe that across all geometries, H-SiNCs feature large electron affinities and highly stabilized anionic states, indicating their potential as n-type materials. Our findings suggest that fine-tuning the size of H-SiNCs along the "zigzag" and "armchair" directions may permit the design of novel n-type electronic materials and spinctronics devices that incorporate both high electron affinities and very low internal reorganization energies. Copyright © 2017, The Authors. All rights reserved.

关键词： Silicene