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Chiral Metamaterials: Room‐Temperature Active Modulation of Valley Dynamics in a Monolayer Semiconductor through Chiral Purcell Effects (Adv. Mater. 49/2019)

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Advanced materials 2019年第49期31卷

作者： Zilong Wu Jingang Li Xiaotian Zhang Joan M. Redwing Yuebing Zheng Walker Department of Mechanical Engineering Materials Science and Engineering Program and Texas Materials Institute The University of Texas at Austin Austin TX 78712 USA Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA 2D Crystal Consortium Materials Research Institute The Pennsylvania State University University Park PA 16802 USA

Graphene/Ni Wire Foam with Multivalent Manganese Oxide Catalysts for Li-O2 Battery Cathode

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Graphene/Ni Wire Foam with Multivalent Manganese Oxide Catal...

MRS Advances

作者： Liu, Chueh Li, Changling Mutlu, Zafer Ozkan, Cengiz S. Ozkan, Mihrimah Materials Science and Engineering Program University of California RiversideCA United States Department of Electrical Engineering University of California RiversideCA United States Department of Mechanical Engineering University of California RiversideCA United States

Herein, commercial Ni foam coated with self-assembled and linearly-aligned Ni wires is utilized as a cost-effective current collector for application in Li-O2 battery. The Ni wires are furthered deposited with graphene layers (g-Ni wire) to improve electrical conductivity. Multivalent Mn oxides consisting of Mn3O4, Mn2O3 and MnCO3 are used as effective oxygen reduction (ORR) and evolution reaction (OER) catalysts deposited on g-Ni wire current collectors. Specific capacities are respective ∼100 and ∼170 mAh g-1 without or with O2 introduction into the cell. The relative facile synthesis process requiring merely solution-based synthesis at ambient pressure, low temperature and short process time renders the Mn oxides/g-Ni wire electrode promising for Li-O2 battery application. © 2017 materials Research Society.

关键词： Oxides

Probing hyperbolic polaritons using infrared attenuated total reflectance micro-spectroscopy

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arXiv 2018年

作者： Folland, Thomas G. Maß, Tobias W.W. Matson, Joseph R. Ryan Nolen, J. Liu, Song Watanabe, Kenji Taniguchi, Takashi Edgar, James H. Taubner, Thomas Caldwell, Joshua D. Department of Mechanical Engineering Vanderbilt University NashvilleTN37212 United States RWTH Aachen University Aachen52056 Germany Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN37212 Department of Chemical Engineering Kansas State University ManhattanKS66506 United States National Institute for Materials Science Tsukuba Japan

Hyperbolic polariton modes are highly appealing for a broad range of applications in nanophotonics, including surfaced enhanced sensing, sub-diffractional imaging and reconfigurable metasurfaces. The existence of this type of mode depends on extreme anisotropy in the optical properties of a natural or artificial material. However, due to their high in-plane momentum (short polariton wavelength), these hyperbolic polaritons cannot be launched by light propagating in free space. Here we show that attenuated total reflectance micro-spectroscopy (ATR) using standard spectroscopic tools can launch hyperbolic polaritons in a Kretschmann-Raether configuration. We measure multiple hyperbolic and dielectric modes within the naturally hyperbolic material hexagonal boron nitride as a function of different isotopic enrichments and flake thickness. This overcomes the technical challenges of measurement approaches based on nanostructuring, or scattering scanning nearfield optical microscopy. Ultimately, our ATR approach allows us to compare the optical properties of small-scale materials prepared by different techniques systematically. Copyright © 2018, The Authors. All rights reserved.

关键词： Photons

mechanical acceleration of capture and detection rate of DNA molecules by motorizing bio-opto-plasmonic microsensors

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arXiv 2018年

作者： Guo, Jianhe Kim, Kwanoh Vandeventer, Peter Fan, Donglei Materials Science and Engineering Program Texas Materials Institute University of Texas at Austin AustinTX78712 United States Department of Mechanical Engineering University of Texas at Austin AustinTX78712 United States Defense Threat Reduction Agency Fort BelvoirVA22060 United States

Efficient capture and detection of minute amount of deoxyribonucleic acid (DNA) molecules are pivotal for an array of modern gene technologies which are widely utilized in medical, forensic and defense applications, including DNA extraction, preconcentration, and separation. In this work, we propose a rational mechanism to substantially accelerate the capture and detection efficiency of DNA molecules by actively motorizing designed Raman microsensors. At least 4-fold enhancement has been achieved on the microsensors rotating at 1200 rpm. The process is monitored dynamically and in-situ from the biosilica based microsensors, owing to the ultrasensitivity provided by the opto-plasmonic enhancement. The fundamental working mechanism is investigated systematically, and can be attributed to the Nernst diffusion layer thinning effect induced by mechanical motions. This research initiated a new and reliable approach for remarkably enhancing the capture and detection efficiency of biomolecules, which could make far-reaching impact to biosensing, DNA technologies, and microfluidic Total Analysis Systems. Copyright © 2018, The Authors. All rights reserved.

关键词： Micromotors

High-entropy high-hardness metal carbides discovered by entropy descriptors

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arXiv 2018年

作者： Sarker, Pranab Harrington, Tyler Toher, Cormac Oses, Corey Samiee, Mojtaba Maria, Jon-Paul Brenner, Donald W. Vecchio, Kenneth S. Curtarolo, Stefano Department of Mechanical Engineering and Materials Science Duke University DurhamNC27708 United States Materials Science and Engineering Program University of California San Diego La JollaCA92093 United States Department of NanoEngineering University of California San Diego La JollaCA92093 United States Department of Materials Science and Engineering North Carolina State University RaleighNC27695 United States Materials Science Electrical Engineering Physics and Chemistry Duke University DurhamNC27708 United States Fritz-Haber-Institut der Max-Planck-Gesellschaft Berlin-Dahlem14195 Germany

High-entropy materials have attracted considerable interest due to the combination of useful properties and promising applications. Predicting their formation remains the major hindrance to the discovery of new systems. Here we propose a descriptor — entropy forming ability — for addressing synthesizability from first principles. The formalism, based on the energy distribution spectrum of randomized calculations, captures the accessibility of equally-sampled states near the ground state and quantifies configurational disorder capable of stabilizing high-entropy homogeneous phases. The methodology is applied to disordered refractory 5-metal carbides — promising candidates for high-hardness applications. The descriptor correctly predicts the ease with which compositions can be experimentally synthesized as rock-salt high-entropy homogeneous phases, validating the ansatz, and in some cases, going beyond intuition. Several of these materials exhibit hardness up to 50% higher than rule of mixtures estimations. The entropy descriptor method has the potential to accelerate the search for high-entropy systems by rationally combining first principles with experimental synthesis and characterization. Copyright © 2018, The Authors. All rights reserved.

关键词： Entropy

Stretchable Electronics: Biaxially Stretchable Ultrathin Si Enabled by Serpentine Structures on Prestrained Elastomers (Adv. Mater. Technol. 1/2019)

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Advanced materials Technologies 2019年第1期4卷

作者： Kyoseung Sim Yuhang Li Jizhou Song Cunjiang Yu Materials Science and Engineering Program University of Houston Houston TX 77204 USA Institute of Solid Mechanics Beihang University Beijing 100191 China Department of Engineering Mechanics Soft Matter Research Center and Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University Hangzhou Zhejiang 310027 China Department of Mechanical Engineering Department of Electrical and Computer Engineering Department of Biomedical Engineering Materials Science and Engineering Program Texas Center for Superconductivity at the University of Houston University of Houston Houston TX 77204 USA

Multifunctional stimuli responsive polymer-gated iron and gold-embedded silica nano golf balls:Nanoshuttles for targeted on-demand theranostics

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Bone Research 2017年第4期5卷 343-356页

作者： Liping Wang Grace Jang Deependra Kumar Ban Vrinda Sant Jay Seth Sami Kazmi Nirav Patel Qingqing Yang Joon Lee Woraphong Janetanakit Shanshan Wang Brian P Head Gennadi Glinsky Ratneshwar Lai School of Biomedical Engineering Shanghai Jiaotong UniverityShanghaiChina Department of Mechanical and Aerospace Engineering La JollaCAUSA Materials Science and Engineering Program La JollaCAUSA Department of Nanoengineering La JollaCAUSA Department of Chemical Engineering University of California San DiegoLa JollaCAUSA Departrnenf of Bioengineering La JollaCAUSA Department of Anesthesiology La JollaCAUSA Veterans Affairs San Diego Healthcare System San DiegoCAUSA Institute of Engineering in Medicine La JollaCAUSA

Multi-functional nanoshuttles for remotely targeted and on-demand delivery of therapeutic molecules and imaging to defined tissues and organs hold great potentials in personalized medicine, including precise early diagnosis, efficient prevention and therapy without toxicity. Yet, in spite of 25 years of research, there are still no such shuttles available. To this end, we have designed magnetic and gold nanoparticles （NP）-embedded silica nanoshuttles （MGNSs） with nanopores on their surface. Fluorescently labeled Doxombicin （DOX）, a cancer drug, was loaded in the MGNSs as a payload. DOX loaded MGNSs were encapsulated in heat and pH sensitive polymer P（NIPAM-co- MAA） to enable controlled release of the payload. Magnetically-guided transport of MGNSs was examined in：（a） a glass capillary tube to simulate their delivery via blood vessels; and （b） porous hydrogels to simulate their transport in composite human tissues, including bone, cartilage, tendon, muscles and blood-brain barrier {BBB）. The viscoelastic properties of hydrogels were examined by atomic force microscopy （AFM）. Cellular uptake of DOX- loaded MGNSs and the subsequent pH and temperature-mediated release were demonstrated in differentiated human neurons derived from induced pluripotent stem cells （iPSCs） as well as epithelial HeLa cells. The presence of embedded iron and gold NPs in silica shells and polymer-coating are supported by SEM and TEM. Fluorescence spectroscopy and microscopy documented DOX loading in the MGNSs. Time-dependent transport of MGNSs guided by an external magnetic field was observed in both glass capillary tubes and in the porous hydrogel. AFM results affirmed that the stiffness of the hydrogels model the rigidity range from soft tissues to bone. pH and temperature-dependent drug release analysis showed stimuli responsive and gradual drug release. Cells＇ viability MTT assays showed that MGNSs are non-toxic. The cell death from on-demand DOX release was observed in both neurons and ep

关键词： Multifunctional stimuli responsive polymer-gated iron

Ultrafast Intercalation Enabled by Strong Solvent–Host Interactions: Understanding Solvent Effect at the Atomic Level

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Angewandte Chemie 2019年第48期131卷

作者： Yue Zhu Yujin Ji Zhengyu Ju Kang Yu Paulo J. Ferreira Yuanyue Liu Guihua Yu Materials Science and Engineering Program and Department of Mechanical Engineering The University of Texas at Austin Austin TX 78712 USA International Iberian Nanotechnology Laboratory Braga 4715-330 Portugal Mechanical Engineering Department and IDMEC Instituto Superior Técnico University of Lisbon Av. Rovisco Pais Lisboa 1049-001 Portugal

Solvents play an essential role in many areas of chemistry and is the cornerstone of understanding reactivity in solution‐phase reactions. Solvent effects have been widely observed in intercalation reactions; however, understanding of the influence of solvents on the thermodynamics and kinetics remains largely elusive in intercalation chemistry. Now, the solvent‐dependent kinetics of ferrocene intercalation into a layered vanadyl phosphate (VOPO 4 ⋅2 H 2 O) host is presented, with a special focus on primary alcohols. From methanol to 1‐hexnaol, the intercalation rate peaks in 1‐propanol (80 times faster than the slowest case in methanol). Similar kinetics of exfoliation are also found in these solvents without ferrocene. The correlation between intercalation and exfoliation is understood at atomic level by DFT calculations, which reveal the role of pre‐intercalated solvent molecules play in intralayer interactions, interlayer expansion, and layer sliding.

关键词： Exfoliation Lösungsmitteleffekte Lösungsmittel-Präinterkalation Lösungsmittel-Wirt-Wechselwirkungen Ultraschnelle Interkalation

Giant thermal Hall conductivity from neutral excitations in the pseudogap phase of cuprates

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arXiv 2019年

作者： Grissonnanche, G. Legros, A. Badoux, S. Lefrançois, E. Zatko, V. Lizaire, M. Laliberté, F. Gourgout, A. Zhou, J.-S. Pyon, S. Takayama, T. Takagi, H. Ono, S. Doiron-Leyraud, N. Taillefer, L. Institut quantique Département de physique & RQMP Université de Sherbrooke SherbrookeQCJ1K 2R1 Canada SPEC CEA CNRS-UMR3680 Université Paris-Saclay Gif-sur-Yvette Cedex91191 France Materials Science and Engineering Program Mechanical Engineering University of Texas at Austin AustinTX78712 United States Department of Advanced Materials University of Tokyo Kashiwa277-8561 Japan Central Research Institute of Electric Power Industry Kanagawa240-0196 Japan Canadian Institute for Advanced Research TorontoONM5G 1Z8 Canada

The nature of the pseudogap phase of cuprates remains a major puzzle. Although there are indications that this phase breaks various symmetries, there is no consensus on its fundamental nature1. Although Fermi-surface2, transport3 and thermodynamic4 signatures of the pseudogap phase are reminiscent of a transition into a phase with antiferromagnetic order5,6, there is no evidence for an associated long-range magnetic order. Here we report measurements of the thermal Hall conductivity κxy in the normal state of four different cuprates (La1.6-xNd0.4SrxCuO4, La1.8-xEu0.2SrxCuO4, La2-xSrxCuO4, and Bi2Sr2-xLaxCuO6+δ) and show that a large negative κxy signal is a property of the pseudogap phase, appearing with the onset of that phase at the critical doping p*. Since it is not due to charge carriers – as it persists when the material becomes an insulator, at low doping – or magnons – as it exists in the absence of magnetic order – or phonons – since skew scattering is very weak, we attribute this κxy signal to exotic neutral excitations, presumably with spin chirality7. The thermal Hall conductivity in the pseudogap phase of cuprates is reminiscent of that found in insulators with spin-liquid states8,9,10. In the Mott insulator La2CuO4, it attains the highest known magnitude of any insulator11. Copyright © 2019, The Authors. All rights reserved.

关键词： Copper compounds