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Dynamic self-stiffening in liquid crystal elastomers
Mimicking the behaviour of biological tissues requires finding biocompatible materials that can strengthen in response to external forces. Agrawal et al. show that polydomain nematic liquid crystal elastomers become unexpectedly stiffer when subjected to a small amplitude and repetitive compression.
- Aditya Agrawal
- , Alin C. Chipara
- & Rafael Verduzco
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| Open AccessNear-ideal theoretical strength in gold nanowires containing angstrom scale twins
Low-dimensional materials containing defects such as twin boundaries are known to fail well below their theoretical strength due to surface imperfections. Here, Wang et al. observe strengths close to the ideal limit in gold nanowires with angstrom scale twins, where homogeneous dislocation nucleation controls deformation.
- Jiangwei Wang
- , Frederic Sansoz
- & Scott X. Mao
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High-strength and thermally stable bulk nanolayered composites due to twin-induced interfaces
Nanostructured metals are known to exhibit poor thermal stability, reducing their high strength at elevated temperatures. Here, Zheng et al. fabricate a bulk two-phase bimetal composite that retains its high strength after annealing at 500 °C for 1 h.
- Shijian Zheng
- , Irene J. Beyerlein
- & Nathan A. Mara
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| Open AccessCritical fictive temperature for plasticity in metallic glasses
Toughness of metallic glasses varies widely, with values spanning from very brittle to exceptionally tough. Kumar et al.report a characteristic fictive temperature, which can explain this widespread behaviour and provide guidelines for synthesis of ductile metallic glasses.
- Golden Kumar
- , Pascal Neibecker
- & Jan Schroers
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Athermal photofluidization of glasses
Glasses are solid when cold, but when mixed with the correct dye can be fluidized by light. Fang et al.show that each photon absorbed in an azobenzen-based molecule layer produces an efficient local heating up to 800 K to melt the glass but without altering the average temperature.
- G.J. Fang
- , J.E. Maclennan
- & N.A. Clark
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Blood-clotting-inspired reversible polymer–colloid composite assembly in flow
Blood clotting is caused by biopolymer-mediated aggregation of platelets and is enhanced by fast shear flows. Chen et al. find a similar process that arises during the self-assembly of polymer–colloid composites—a process that can be controlled and even reversed by flow rate and interparticle interaction.
- Hsieh Chen
- , Mohammad A. Fallah
- & Alfredo Alexander-Katz
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Supercooled liquids with enhanced orientational order
Medium-range structural ordering is expected to exist in supercooled liquids yet direct probes of this are difficult to achieve. Capponi et al.report a new metastable phase of organic molecular glasses exhibiting long-living, highly enhanced orientational order above its glass transition temperature.
- Simona Capponi
- , Simone Napolitano
- & Michael Wübbenhorst
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Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases
The mechanical properties of structural ceramics are characterized by a high degree of fragility and brittleness. This study demonstrates that, contrary to expectation, their brittleness can be reduced substantially by introducing nanopores together with weak grain boundary phases.
- K. Madhav Reddy
- , J.J. Guo
- & M.W. Chen
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| Open AccessOptical detection of a single rare-earth ion in a crystal
The optical transitions that occur in rare-earth-doped crystals offer promise for quantum information storage and processing. Kolesovet al.report the optical detection of a single praseodymium ion residing in a crystal host by using an excited-state absorption process to enhance its fluorescence yield.
- R. Kolesov
- , K. Xia
- & J. Wrachtrup
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| Open AccessRoles of icosahedral and crystal-like order in the hard spheres glass transition
The dynamics and structure of the glass transition in liquids is still debated. Using particle-level confocal microscopy, Leocmach and Tanaka investigate supercooled colloidal liquids and distinguish different scenarios for glassy slow dynamics, suggesting that local ordering may only play a minor role.
- Mathieu Leocmach
- & Hajime Tanaka
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| Open AccessApproaching the ideal elastic limit of metallic glasses
The elastic limit represents the maximum stress and strain a material can withstand and is well characterized in many crystalline solids, yet remains elusive for metallic glasses. Here, this limit is investigated in submicron metallic glass structures and is found to be twice as high as that of bulk samples.
- Lin Tian
- , Yong-Qiang Cheng
- & Evan Ma
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Interface engineering of quantum Hall effects in digital transition metal oxide heterostructures
Topological insulators are a class of materials with an unusual band structure that makes them metallic at the surface and insulating in the bulk. Okamoto and co-workers use electronic structure calculations to predict a new family of possible topological insulators based on transition-metal oxides.
- Di Xiao
- , Wenguang Zhu
- & Satoshi Okamoto
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Band structure engineering in (Bi1−xSbx)2Te3 ternary topological insulators
The unique band structure of topological insulators gives rise to insulating bulk and unusual metallic surface properties. By tuning the content of Sb in the ternary compound (Bi1–xSbx)2Te3, Wang and collaborators show it is possible to control the precise features of the band structure in a continuous fashion.
- Jinsong Zhang
- , Cui-Zu Chang
- & Yayu Wang
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| Open AccessA new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum
Mechanical annealing is a process through which the dislocation density in submicrometre metal crystals can be removed purely by applying a mechanical stress. This study shows that mechanical annealing occurs in body centred cubic molybdenum, and not only in face centred crystals as previously thought.
- Ling Huang
- , Qing-Jie Li
- & Evan Ma
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Rational design of a binary metal alloy for chemical vapour deposition growth of uniform single-layer graphene
Graphene may be used in nanoscale electronics and devices, but the ability to synthesise uniform graphene with well-controlled layer numbers is necessary for these applications. Using a Ni–Mo alloy, this study demonstrates single-layer graphene growth with 100% surface coverage and tolerance to variations in growth conditions.
- Boya Dai
- , Lei Fu
- & Zhongfan Liu
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| Open AccessEvidence of superdense aluminium synthesized by ultrafast microexplosion
At extreme temperature and pressure, materials can form new dense phases with unusual physical properties. Here, laser-induced microexplosions are used to produce a superdense, stable, body-centred-cubic form of aluminium, which was previously predicted to exist at pressures above 380GPa.
- Arturas Vailionis
- , Eugene G. Gamaly
- & Saulius Juodkazis
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Helium penetrates into silica glass and reduces its compressibility
SiO2 glass and helium are important in various fields of science and engineering. Sato et al. show SiO2glass to be less compressible in helium under high pressure, which may be relevant for the interpretation of high-pressure experiments and in the design of new materials.
- Tomoko Sato
- , Nobumasa Funamori
- & Takehiko Yagi
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Cooperative material transport during the early stage of sintering
Sintering is the basis for the production of many metallic and composite materials. Gruppet al. use a new technique to measure the rotation of microscopic copper particles during sintering and find intrinsic rotations to be the dominant movement.
- R. Grupp
- , M. Nöthe
- & J. Banhart
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| Open AccessPatterns and flow in frictional fluid dynamics
Pattern-forming processes in simple fluids and suspensions are well understood, but displacement morphologies in frictional fluids and granular mixtures have not been studied extensively. Sandneset al. consider the effects of Coulomb friction and compressibility on the fluid dynamics of granular mixtures.
- B. Sandnes
- , E.G. Flekkøy
- & H. See
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| Open AccessGapless spin liquid of an organic triangular compound evidenced by thermodynamic measurements
Frustrated magnetic systems can form an exotic quantum spin-liquid ground state, in which strongly correlated spins fluctuate in the spin lattices. Here, the low-temperature electronic state of a charge-transfer compound is found to form a gapless spin liquid.
- Satoshi Yamashita
- , Takashi Yamamoto
- & Reizo Kato
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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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Tablet-level origin of toughening in abalone shells and translation to synthetic composite materials
The mechanism responsible for the toughness of nacre, the hierarchical iridescent material in seashells, is still unknown. Espinosa and colleagues show that the waviness of its tablets leads to interfacial hardening, and ultimately to energy dissipation, when the material is stressed.
- Horacio D. Espinosa
- , Allison L. Juster
- & Pablo D. Zavattieri
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Cyclic hardening in bundled actin networks
Materials such as rubber tend to soften when cyclically deformed. Here, however, the authors find that bundled actin networks can show cyclic hardening and retain a memory of the maximum strain they have been subjected to.
- K. M. Schmoller
- , P. Fernández
- & A. R. Bausch
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Nanostructural hierarchy increases the strength of aluminium alloys
Improving the properties of metallic alloys is important to develop new lightweight materials. In this paper, we show that an aluminium (Al) alloy containing a hierarchy of nanostructures in a solid solution with a high density of dislocations is capable of beating strength records for Al alloys while maintaining good ductility.
- Peter V. Liddicoat
- , Xiao-Zhou Liao
- & Simon P. Ringer