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| Open AccessAdvantageous grain boundaries in iron pnictide superconductors
High critical temperature superconductors could be used to produce ideal electric power lines, but the misalignment of crystalline grain boundaries reduces current density. Here, pnictide superconductors are found to be more tolerant to misaligned grain boundaries than cuprates.
- Takayoshi Katase
- , Yoshihiro Ishimaru
- & Hideo Hosono
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| Open AccessMesoscale flux-closure domain formation in single-crystal BaTiO3
Flux-closure patterns are rarely observed in ferroelectric materials and almost exclusively form at the nanoscale. McQuaidet al. report mesoscopic dipole closure patterns formed in free-standing single-crystal lamellae of BaTiO3, thought to result from an unusual set of experimental conditions.
- R.G.P. McQuaid
- , L.J. McGilly
- & J.M. Gregg
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Encapsulation of single-molecule magnets in carbon nanotubes
Single-molecule magnets could be useful for the development of spintronic devices. Here single-molecule magnets are encapsulated in carbon nanotubes without affecting the properties of the guest molecules, which may be useful in the development of spintronic or high-density magnetic storage devices.
- Maria del Carmen Giménez-López
- , Fabrizio Moro
- & Andrei N. Khlobystov
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Confined propagation of covalent chemical reactions on single-walled carbon nanotubes
Covalent reactions on carbon nanotube surfaces typically occur at random positions on the hexagonal lattice. Denget al. show that Billups–Birch reductive alkylation takes place at, and propagates from, sp3defect sites, leading to confinement of the reaction fronts in the tubular direction.
- Shunliu Deng
- , Yin Zhang
- & YuHuang Wang
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Article
| Open AccessCascaded logic gates in nanophotonic plasmon networks
Optical computing, involving on-chip integrated logic units, could provide improved performance over semiconductor-based computing. Here, a binary NOR gate is developed from cascaded OR and NOT gates in four-terminal plasmonic nanowire networks; the work could lead to new optical computing technologies.
- Hong Wei
- , Zhuoxian Wang
- & Hongxing Xu
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Hierarchical MnMoO4/CoMoO4 heterostructured nanowires with enhanced supercapacitor performance
The construction of three-dimensional hierarchical heterostructures can lead to improved electrochemical properties. Maiet al. synthesize a three-dimensional multicomponent oxide, MnMoO4/CoMoO4, which is used to produce a supercapacitor with enhanced performance.
- Li-Qiang Mai
- , Fan Yang
- & Yan-Zhu Luo
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| Open AccessMediatorless high-power glucose biofuel cells based on compressed carbon nanotube-enzyme electrodes
Glucose biofuel cells can be used to produce clean energy from renewable sources, but their use is limited by poor stability and low power output. In this study, bioelectrodes are fabricated using carbon nanotubes and the resulting biofuel cells have improved stability and power.
- Abdelkader Zebda
- , Chantal Gondran
- & Serge Cosnier
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Imaging local electronic corrugations and doped regions in graphene
The unoccupied electronic levels of graphene are modified by corrugation, doping and presence of impurities. Here, the authors map discrete electronic domains within a single graphene sheet using scanning transmission X-ray microscopy and provide insight into the modification of unoccupied levels.
- Brian J. Schultz
- , Christopher J. Patridge
- & Sarbajit Banerjee
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Biologically inspired achromatic waveplates for visible light
Waveplates are used in optoelectronics to alter the polarization of light, but they do not typically perform achromatically, which is important for applications such as three-dimensional displays. Here, biologically inspired periodically multilayered structures are produced, which function as achromatic visible-light waveplates.
- Yi-Jun Jen
- , Akhlesh Lakhtakia
- & Jyun-Rong Lai
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Observing chaos for quantum-dot microlasers with external feedback
Optoelectronic devices such as conventional semiconductor lasers are used to study the chaotic behaviour of nonlinear systems. Here chaos is observed for quantum-dot microlasers operating close to the quantum limit with potential for new directions in the study of chaos in quantum systems.
- Ferdinand Albert
- , Caspar Hopfmann
- & Ido Kanter
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Collective fluorescence enhancement in nanoparticle clusters
Single nanoparticles are known to emit light intermittently, or 'blink', but the mechanisms describing this phenomenon are not fully understood. This study demonstrates that, for small clusters of blinking nanoparticles, the number of particles within a cluster dramatically influences blinking time.
- Siying Wang
- , Claudia Querner
- & Marija Drndic
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Article
| Open AccessPromotion of water-mediated carbon removal by nanostructured barium oxide/nickel interfaces in solid oxide fuel cells
Anodes composed of nickel/yttria-stabilized zirconia in solid oxide fuel cells are known to suffer from coking, which reduces their performance. Here, Yang and colleagues report a new barium oxide/nickel anode, which efficiently oxidizes fuel with minimum carbon buildup.
- Lei Yang
- , YongMan Choi
- & Meilin Liu
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A synthetic icosahedral DNA-based host–cargo complex for functional in vivo imaging
Encapsulating molecules within supramolecular frameworks for potential biological application is challenging. Bhatiaet al. incorporate a fluorescent polymer within an icosahedral DNA nanocapsule, and show that it can be used to target specific cells in vivoand map pH spatially and temporally.
- Dhiraj Bhatia
- , Sunaina Surana
- & Yamuna Krishnan
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An autonomous DNA nanomachine maps spatiotemporal pH changes in a multicellular living organism
Many synthetic DNA nanomachines have been developed and demonstratedin vitro, but their use in living organisms has not been reported. Now, a DNA nanomachine, the I-switch, is used to map spatiotemporal pH changes associated with endosomal maturation within coelomocytes of Caenorhabditis elegans.
- Sunaina Surana
- , Jaffar M. Bhat
- & Yamuna Krishnan
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| Open AccessDetermination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation
Nanoparticles continue to find research and industrial applications, but no single technique exists to characterise their physical properties. Now, an analytical ultracentrifugation method is described which allows the simulataneous determination of nanoparticle size, density and molecular weight distribution.
- Randy P. Carney
- , Jin Young Kim
- & Osman M. Bakr
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Experimental demonstration of low-loss optical waveguiding at deep sub-wavelength scales
Metal-based nanostructures offer a solution to scale down photonics to the nanoscale. Sorgeret al. directly demonstrate waveguiding of ultra-small propagating waves at visible and near-infrared frequencies using NSOM imaging, with the potential for nanoscale photonic applications such as bio-sensing.
- Volker J. Sorger
- , Ziliang Ye
- & Xiang Zhang
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| Open AccessNanoantenna-enhanced ultrafast nonlinear spectroscopy of a single gold nanoparticle
Optical nanoantennas can be used for spectroscopic investigations at previously unattainable dimensions. Schumacheret al.describe time-resolved antenna-enhanced ultrafast nonlinear optical spectroscopy and determine the transient absorption signal of a single gold nanoparticle.
- Thorsten Schumacher
- , Kai Kratzer
- & Markus Lippitz
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Stabilizing lithium–sulphur cathodes using polysulphide reservoirs
Lithium–sulphur batteries may achieve higher energy densities than conventional lithium-ion cells, but the dissolution of sulphur intermediates is a continuing challenge. Here this problem is overcome using a cathode with a mesoporous structure that is able to accommodate intermediate polysulphide anions.
- Xiulei Ji
- , Scott Evers
- & Linda F. Nazar
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Article
| Open AccessRevealing the molecular structure of single-molecule junctions in different conductance states by fishing-mode tip-enhanced Raman spectroscopy
The conductance of single-molecule junctions is affected by the structure of the molecule and how it is bound to the electrodes, which may be examined using Raman spectroscopy. Liuet al. have developed 'fishing-mode' tip-enhanced Raman spectroscopy, which allows the simultaneous determination of conductance and Raman spectra.
- Zheng Liu
- , Song-Yuan Ding
- & Zhong-Qun Tian
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| Open AccessLarge-scale single-chirality separation of single-wall carbon nanotubes by simple gel chromatography
Large-scale separation of single-wall carbon nanotubes into populations of single chirality is a significant challenge in the practical application of nanotubes. Now, using multicolumn gel chromatography, the large-scale separation of 13 different carbon nanotube species is achieved.
- Huaping Liu
- , Daisuke Nishide
- & Hiromichi Kataura
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| Open AccessTravelling-wave resonant four-wave mixing breaks the limits of cavity-enhanced all-optical wavelength conversion
Wave mixing in optical resonators suffers from strong bandwidth constraints, hindering practical implementation. Morichettiet al. report travelling-wave four-wavemixing in coupled ring resonators, which combines the efficiency enhancement of resonant propagation with a wide-band conversion process.
- Francesco Morichetti
- , Antonio Canciamilla
- & Andrea Melloni
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Two-dimensional enzyme diffusion in laterally confined DNA monolayers
Little is known about the effects of molecular crowding and confinement on biomolecule function. Castronovoet al. investigate the reactions of restriction enzymes with DNA confined in bushy matrices and find that the enzymes enter at the side of the matrix before diffusing two-dimensionally.
- Matteo Castronovo
- , Agnese Lucesoli
- & Giacinto Scoles
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Synthesis of hexagonal close-packed gold nanostructures
Solid gold is most stable as a face-centred cubic structure, and stable colloidal gold with hexagonal close packing has not been produced. Huanget al.prepare square gold sheets with hexagonal close packing that are stable under ambient conditions.
- Xiao Huang
- , Shaozhou Li
- & Hua Zhang
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Plasmonic beaming and active control over fluorescent emission
Nanometallic optical antennas can concentrate light into a deep-subwavelength volume for sensor and photovoltaic applications. Junet al. demonstrate an optical antenna design that achieves a high level of control over fluorescent emission for a wide range of nanoscale optical spectroscopy applications.
- Young Chul Jun
- , Kevin C.Y. Huang
- & Mark L. Brongersma
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A monolithically integrated plasmonic infrared quantum dot camera
Infrared cameras are used for night vision and in medical diagnostics, but currently only present monochrome images. Krishnaet al. demonstrate a monolithically intergrated plasmonic infrared quantum dot camera as a step towards coloured infrared imaging.
- Sang Jun Lee
- , Zahyun Ku
- & Sam Kyu Noh
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| Open AccessNano-engineered electron–hole exchange interaction controls exciton dynamics in core–shell semiconductor nanocrystals
Electron–hole exchange interaction is an intrinsic property of semiconductors, which affects their fine structure. Brovelliet al. demonstrate a nanoengineering-based approach that provides control over the exchange interaction energy at nearly constant emission energy, which cannot be carried out using core-only nanocrystals.
- S. Brovelli
- , R.D. Schaller
- & V.I. Klimov
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| Open AccessThe Meissner effect in a strongly underdoped cuprate above its critical temperature
In the pseudogap state of cuprates, although diamagnetic signals have been detected, a Meissner effect has never been observed. Morenzoni and colleagues probe the local diamagnetic response in the normal state of an underdoped layer showing that a 'barrier' layer exhibits a Meissner effect.
- Elvezio Morenzoni
- , Bastian M. Wojek
- & Ivan Božović
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| Open Access3D optical Yagi–Uda nanoantenna array
Nanoantennas may be important for future photonic circuits; they combine an emitter or detector with free-space propagation of light. Dregelyet al. fabricate an array of 3D optical Yagi–Uda nanoantennas and show that radiofrequency antenna array concepts applied to the optical regime can provide improved directional properties.
- Daniel Dregely
- , Richard Taubert
- & Harald Giessen
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Tip-enhanced photovoltaic effects in bismuth ferrite
Bismuth ferrite has photoelectric properties that make it an attractive alternative for use in photovoltaic devices. Here, using photoelectric atomic force microscopy, the authors show that photogenerated carriers can be collected by the tip and suggest that this can be used in photoelectric applications.
- Marin Alexe
- & Dietrich Hesse
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| Open AccessDevelopment of a universal stress sensor for graphene and carbon fibres
Embedding carbon fibres in polymer matrices provides significant gains in strength and stiffness. Here, the Raman G peak of carbon fibre is studied in relation to applied strain and referenced to graphene; the work could facilitate stress measurements of carbon fibre polymer composites.
- Otakar Frank
- , Georgia Tsoukleri
- & Costas Galiotis
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| Open AccessWhispering gallery microresonators for second harmonic light generation from a low number of small molecules
Small molecules can be detected by second harmonic light generation, but sensitive detection usually requires a large number of molecules and a high-power laser source. Here, relatively low numbers of molecules are detected using Q spherical microresonators and low average power.
- J.L. Dominguez-Juarez
- , G. Kozyreff
- & Jordi Martorell
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A nanomechanical interface to rapid single-molecule interactions
Single-molecule force spectroscopy is used to study single molecule interactions, but probing short-lived events is difficult. Here, a nanomechanical interface is developed, which allows the study of microsecond timescale interactions.
- Mingdong Dong
- & Ozgur Sahin
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Coherent electron–phonon coupling in tailored quantum systems
Graphene and InAs nanowires are both promising materials for coherent spin manipulation, but coupling between a quantum system and its environment leads to decoherence. Here, the contribution of electron–phonon coupling to decoherence in graphene and InAs nanowire is studied.
- P. Roulleau
- , S. Baer
- & T. Ihn
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Nanofriction in cold ion traps
Cold ion traps have not previously been used to study sliding friction between crystal lattices. Here, Benassiet al. use simulations to show that cold ion traps could be used for detailed investigation of atomic scale friction.
- A. Benassi
- , A. Vanossi
- & E. Tosatti
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| Open AccessObservation and electric current control of a local spin in a single-molecule magnet
In molecular spintronics, the spin state of a molecule may be switched by changing the molecular structure. Here, the spin of a single-molecule magnet is switched by applying an electric current using a scanning tunnelling microscope, which may aid in information coding at the single-molecule level.
- Tadahiro Komeda
- , Hironari Isshiki
- & Masahiro Yamashita
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Optical virtual imaging at 50 nm lateral resolution with a white-light nanoscope
Lenses are restricted by diffraction to imaging features roughly the size of visible wavelengths. Wanget al. develop a white-light nanoscope that uses optically transparent spherical silica lenses to virtually image, in the far-field, features down to 50 nm resolution.
- Zengbo Wang
- , Wei Guo
- & Minghui Hong
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| Open AccessA fast and low-power microelectromechanical system-based non-volatile memory device
New memory devices are being developed to overcome the limitations of conventional silicon-based flash memory. Here, a non-volatile memory design is reported that uses a micromechanical cantilever to charge and discharge a floating gate, which controls charge transport through a carbon nanotube field-effect transistor.
- Sang Wook Lee
- , Seung Joo Park
- & Yung Woo Park
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| Open AccessTransport spectroscopy of non-equilibrium many-particle spin states in self-assembled quantum dots
All-electrical quantum state manipulation is highly desirable for quantum information technologies. In this study, the authors demonstrate the preparation and detection of excited many-particle spin states in self-assembled quantum dots at 4 K, using only electrical means.
- B. Marquardt
- , M. Geller
- & A. Lorke
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Ionic polypeptides with unusual helical stability
Water-soluble peptides with stable α-helical conformations are desirable for a range of applications, but incorporating charged residues to improve solubility usually leads to reduced helical stability. Here, polypeptides produced from amino acids with elongated charged side chains are found to be water soluble and exhibit very high helical stability.
- Hua Lu
- , Jing Wang
- & Jianjun Cheng
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| Open AccessInterconnect-free parallel logic circuits in a single mechanical resonator
Eliminating wiring in transistors could lead to high integration densities and low power consumption. Here, multiple logic gates are implemented in a microelectromechanical resonator by parametrically mixing binary information channels corresponding to mechanical oscillations of the resonator at different frequencies.
- I. Mahboob
- , E. Flurin
- & H. Yamaguchi
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Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry
Polycrystalline substrates are a hindrance to the realization of high-definition plasmonic nanostructures. In this paper the authors chemically grow large and thin gold single crystals, and show that they can be coupled with top-down fabrication methods to produce high-quality nanostructures with good optical properties.
- Jer-Shing Huang
- , Victor Callegari
- & Bert Hecht
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Spherical hyperlens for two-dimensional sub-diffractional imaging at visible frequencies
Although hyperlenses made of metamaterials can image sub-diffraction-limited objects, they are limited to one-dimensional magnification and ultraviolet frequencies. Here, the authors demonstrate a spherical hyperlens for visible light far-field imaging, with a resolution of 160 nm in both lateral dimensions.
- Junsuk Rho
- , Ziliang Ye
- & Xiang Zhang
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| Open AccessDiscrete plasticity in sub-10-nm-sized gold crystals
Deformations in nanocrystals smaller than 10 nm are not well understood. The authors perform compression high-resolution transmission electron microscopy studies of gold nanoparticles, and determine that the nanoparticles deform through the emission of partial dislocations from free surfaces.
- He Zheng
- , Ajing Cao
- & Scott X. Mao
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Article
| Open AccessSingle-molecule identification via electric current noise
Molecular fluctuations are a source of noise that can impede single-molecule identification. Here, quantum-fluctuation-induced inelastic noise is observed as current fluctuations in individual molecules, suggesting that inelastic noise could be used as a molecular signature.
- Makusu Tsutsui
- , Masateru Taniguchi
- & Tomoji Kawai
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Article
| Open AccessField-induced water electrolysis switches an oxide semiconductor from an insulator to a metal
Water is composed of the electrochemically active species, H+ and OH−, but has not been used as an active electronic material. In this study, a field-effect transistor is developed that uses water-infiltrated nanoporous glass as the gate insulator; this new application of water may be useful in electronics and energy storage.
- Hiromichi Ohta
- , Yukio Sato
- & Hideo Hosono
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| Open AccessDimensionality-driven insulator–metal transition in A-site excess non-stoichiometric perovskites
Many technological applications would benefit from new ways of bringing complex materials near the insulator–metal transition region. The authors induce, in a Lantanum Strontium Titanate, a transition from insulating to metallic behaviour by structural intercalation of intrinsically insulating units, opening new avenues to engineer these materials.
- Zhongchang Wang
- , Masaki Okude
- & Yuichi Ikuhara
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Piezoelectric-nanowire-enabled power source for driving wireless microelectronics
Energy harvesting through mechanical actions of nanosized components could be useful for powering mobile electronics. Here, the authors grow lead zirconate nanowire arrays at comparatively low temperature and use them to power a macroscopic laser diode.
- Sheng Xu
- , Benjamin J. Hansen
- & Zhong Lin Wang
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One-by-one trap activation in silicon nanowire transistors
Flicker noise in nanoscale field effect transistors deviates from the simple frequency-dependent behaviour of macroscale objects. Here the authors show that Coulomb repulsion between nearby trap sites leads to an order of magnitude reduction in noise in these devices.
- N. Clément
- , K. Nishiguchi
- & D. Vuillaume
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| Open AccessStructural bases for the interaction of frataxin with the central components of iron–sulphur cluster assembly
Frataxin is an essential protein that has been linked to iron–sulphur cluster assembly, and reduced levels are associated with Friedrich's ataxia. In this study, a combination of techniques is used to probe the interactions of the bacterial frataxin orthologue CyaY with the iron–sulphur cluster assembly machinery.
- Filippo Prischi
- , Petr V. Konarev
- & Annalisa Pastore