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  • Tunable room-temperature magnetic skyrmions in Ir/Fe/Co/Pt multilayers
    Nature Mater. (IF 39.737) Pub Date : 2017-07-17
    Anjan Soumyanarayanan, M. Raju, A. L. Gonzalez Oyarce, Anthony K. C. Tan, Mi-Young Im, A. P. Petrović, Pin Ho, K. H. Khoo, M. Tran, C. K. Gan, F. Ernult, C. Panagopoulos

    Magnetic skyrmions are nanoscale topological spin structures offering great promise for next-generation information storage technologies. The recent discovery of sub-100-nm room-temperature (RT) skyrmions in several multilayer films has triggered vigorous efforts to modulate their physical properties for their use in devices. Here we present a tunable RT skyrmion platform based on multilayer stacks of Ir/Fe/Co/Pt, which we study using X-ray microscopy, magnetic force microscopy and Hall transport techniques. By varying the ferromagnetic layer composition, we can tailor the magnetic interactions governing skyrmion properties, thereby tuning their thermodynamic stability parameter by an order of magnitude. The skyrmions exhibit a smooth crossover between isolated (metastable) and disordered lattice configurations across samples, while their size and density can be tuned by factors of two and ten, respectively. We thus establish a platform for investigating functional sub-50-nm RT skyrmions, pointing towards the development of skyrmion-based memory devices.

    更新日期:2017-07-22
  • Electrical pumping and tuning of exciton-polaritons in carbon nanotube microcavities
    Nature Mater. (IF 39.737) Pub Date : 2017-07-17
    Arko Graf, Martin Held, Yuriy Zakharko, Laura Tropf, Malte C. Gather, Jana Zaumseil

    Exciton-polaritons are hybrid light–matter particles that form upon strong coupling of an excitonic transition to a cavity mode. As bosons, polaritons can form condensates with coherent laser-like emission. For organic materials, optically pumped condensation was achieved at room temperature but electrically pumped condensation remains elusive due to insufficient polariton densities. Here we combine the outstanding optical and electronic properties of purified, solution-processed semiconducting (6,5) single-walled carbon nanotubes (SWCNTs) in a microcavity-integrated light-emitting field-effect transistor to realize efficient electrical pumping of exciton-polaritons at room temperature with high current densities (>10 kA cm−2) and tunability in the near-infrared (1,060 nm to 1,530 nm). We demonstrate thermalization of SWCNT polaritons, exciton-polariton pumping rates ~104 times higher than in current organic polariton devices, direct control over the coupling strength (Rabi splitting) via the applied gate voltage, and a tenfold enhancement of polaritonic over excitonic emission. This powerful material–device combination paves the way to carbon-based polariton emitters and possibly lasers.

    更新日期:2017-07-22
  • Dynamic surface self-reconstruction is the key of highly active perovskite nano-electrocatalysts for water splitting
    Nature Mater. (IF 39.737) Pub Date : 2017-07-17
    Emiliana Fabbri, Maarten Nachtegaal, Tobias Binninger, Xi Cheng, Bae-Jung Kim, Julien Durst, Francesco Bozza, Thomas Graule, Robin Schäublin, Luke Wiles, Morgan Pertoso, Nemanja Danilovic, Katherine E. Ayers, Thomas J. Schmidt

    The growing need to store increasing amounts of renewable energy has recently triggered substantial R&D efforts towards efficient and stable water electrolysis technologies. The oxygen evolution reaction (OER) occurring at the electrolyser anode is central to the development of a clean, reliable and emission-free hydrogen economy. The development of robust and highly active anode materials for OER is therefore a great challenge and has been the main focus of research. Among potential candidates, perovskites have emerged as promising OER electrocatalysts. In this study, by combining a scalable cutting-edge synthesis method with time-resolved X-ray absorption spectroscopy measurements, we were able to capture the dynamic local electronic and geometric structure during realistic operando conditions for highly active OER perovskite nanocatalysts. Ba0.5Sr0.5Co0.8Fe0.2O3−δ as nano-powder displays unique features that allow a dynamic self-reconstruction of the material’s surface during OER, that is, the growth of a self-assembled metal oxy(hydroxide) active layer. Therefore, besides showing outstanding performance at both the laboratory and industrial scale, we provide a fundamental understanding of the operando OER mechanism for highly active perovskite catalysts. This understanding significantly differs from design principles based on ex situ characterization techniques.

    更新日期:2017-07-22
  • Carbon nanotubes: Wiry matter–light coupling
    Nature Mater. (IF 39.737) Pub Date : 2017-07-17
    Jeremy J. Baumberg

    Carbon nanotubes: Wiry matter–light coupling Nature Materials, Published online: 17 July 2017; doi:10.1038/nmat4948 Electrical injection into polaritons, built from admixing excitons in carbon nanotubes with light in a surrounding microcavity, has been achieved.

    更新日期:2017-07-22
  • Excitation-wavelength-dependent small polaron trapping of photoexcited carriers in α-Fe2O3
    Nature Mater. (IF 39.737) Pub Date : 2017-07-10
    Lucas M. Carneiro, Scott K. Cushing, Chong Liu, Yude Su, Peidong Yang, A. Paul Alivisatos, Stephen R. Leone

    Small polaron formation is known to limit ground-state mobilities in metal oxide photocatalysts. However, the role of small polaron formation in the photoexcited state and how this affects the photoconversion efficiency has yet to be determined. Here, transient femtosecond extreme-ultraviolet measurements suggest that small polaron localization is responsible for the ultrafast trapping of photoexcited carriers in haematite (α-Fe2O3). Small polaron formation is evidenced by a sub-100 fs splitting of the Fe 3p core orbitals in the Fe M2,3 edge. The small polaron formation kinetics reproduces the triple-exponential relaxation frequently attributed to trap states. However, the measured spectral signature resembles only the spectral predictions of a small polaron and not the pre-edge features expected for mid-gap trap states. The small polaron formation probability, hopping radius and lifetime varies with excitation wavelength, decreasing with increasing energy in the t2g conduction band. The excitation-wavelength-dependent localization of carriers by small polaron formation is potentially a limiting factor in haematite’s photoconversion efficiency.

    更新日期:2017-07-12
  • Valley magnetoelectricity in single-layer MoS2
    Nature Mater. (IF 39.737) Pub Date : 2017-07-10
    Jieun Lee, Zefang Wang, Hongchao Xie, Kin Fai Mak, Jie Shan

    Valley magnetoelectricity in single-layer MoS2 Nature Materials, Published online: 10 July 2017; doi:10.1038/nmat4931 Valley magnetization in single-layer MoS2 is demonstrated by breaking the three-fold rotational symmetry via uniaxial stress. The results are consistent with a theoretical model of valley magnetoelectricity driven by Berry curvature effects.

    更新日期:2017-07-12
  • Strength of the repulsive part of the interatomic potential determines fragility in metallic liquids
    Nature Mater. (IF 39.737) Pub Date : 2017-07-10
    Christopher E. Pueblo, Minhua Sun, K. F. Kelton

    Strength of the repulsive part of the interatomic potential determines fragility in metallic liquids Nature Materials, Published online: 10 July 2017; doi:10.1038/nmat4935 Liquid fragility is a basic characteristic of glasses and there is debate as to what controls it. X-ray scattering of several metallic liquids now suggests that the strength of the repulsive part of the interatomic potential is key.

    更新日期:2017-07-12
  • Revealing crystalline domains in a mollusc shell single-crystalline prism
    Nature Mater. (IF 39.737) Pub Date : 2017-07-10
    F. Mastropietro, P. Godard, M. Burghammer, C. Chevallard, J. Daillant, J. Duboisset, M. Allain, P. Guenoun, J. Nouet, V. Chamard

    Biomineralization integrates complex processes leading to an extraordinary diversity of calcareous biomineral crystalline architectures, in intriguing contrast with the consistent presence of a sub-micrometric granular structure. Hence, gaining access to the crystalline architecture at the mesoscale, that is, over a few granules, is key to building realistic biomineralization scenarios. Here we provide the nanoscale spatial arrangement of the crystalline structure within the ‘single-crystalline’ prisms of the prismatic layer of a Pinctada margaritifera shell, exploiting three-dimensional X-ray Bragg ptychography microscopy. We reveal the details of the mesocrystalline organization, evidencing a crystalline coherence extending over a few granules. We additionally prove the existence of larger iso-oriented crystalline domains, slightly misoriented with respect to each other, around one unique rotation axis, and whose shapes are correlated with iso-strain domains. The highlighted mesocrystalline properties support recent biomineralization models involving partial fusion of oriented nanoparticle assembly and/or liquid droplet precursors.

    更新日期:2017-07-12
  • Dopant compensation in alloyed CH3NH3PbBr3−xClx perovskite single crystals for gamma-ray spectroscopy
    Nature Mater. (IF 39.737) Pub Date : 2017-07-03
    Haotong Wei, Dylan DeSantis, Wei Wei, Yehao Deng, Dengyang Guo, Tom J. Savenije, Lei Cao, Jinsong Huang

    Organic–inorganic halide perovskites (OIHPs) bring an unprecedented opportunity for radiation detection with their defect-tolerance nature, large mobility–lifetime product, and simple crystal growth from solution. Here we report a dopant compensation in alloyed OIHP single crystals to overcome limitations of device noise and charge collection, enabling γ-ray spectrum collection at room temperature. CH3NH3PbBr3 and CH3NH3PbCl3 are found to be p-type and n-type doped, respectively, whereas dopant-compensated CH3NH3PbBr2.94Cl0.06 alloy has over tenfold improved bulk resistivity of 3.6 × 109 Ω cm. Alloying also increases the hole mobility to 560 cm2 V−1 s−1, yielding a high mobility–lifetime product of 1.8 × 10−2 cm2 V−1. The use of a guard ring electrode in the detector reduces the crystal surface leakage current and device dark current. A distinguishable 137Cs energy spectrum with comparable or better resolution than standard scintillator detectors is collected under a small electric field of 1.8 V mm−1 at room temperature.

    更新日期:2017-07-05
  • Playing with defects in metals
    Nature Mater. (IF 39.737) Pub Date : 
    Xiuyan Li, K. Lu

    Playing with defects in metals Nature Materials, Published online: 27 June 2017; doi:10.1038/nmat4929 Xiuyan Li and K. Lu discuss a strategy, alternative to alloying, to tailor the mechanical properties of metals. By engineering defects, metals with bespoke performance might be obtained while reducing the materials' compositional complexity.

    更新日期:2017-07-02
  • Material Witness: Making anyon soup
    Nature Mater. (IF 39.737) Pub Date : 
    Philip Ball

    Material Witness: Making anyon soup Nature Materials, Published online: 27 June 2017; doi:10.1038/nmat4933

    更新日期:2017-07-02
  • Towards sustainable concrete
    Nature Mater. (IF 39.737) Pub Date : 
    Paulo J. M. Monteiro, Sabbie A. Miller, Arpad Horvath

    Towards sustainable concrete Nature Materials, Published online: 27 June 2017; doi:10.1038/nmat4930 Paulo J. M. Monteiro, Sabbie A. Miller and Arpad Horvath provide an overview of the challenges and accomplishments in reducing the environmental burden of concrete production.

    更新日期:2017-07-02
  • Produce and use with care
    Nature Mater. (IF 39.737) Pub Date : 

    Produce and use with care Nature Materials, Published online: 27 June 2017; doi:10.1038/nmat4928

    更新日期:2017-07-02
  • A sustainable material world
    Nature Mater. (IF 39.737) Pub Date : 

    A sustainable material world Nature Materials, Published online: 27 June 2017; doi:10.1038/nmat4932 By considering the environmental impact of materials through their whole life cycle, materials scientists can help develop more sustainable alternatives.

    更新日期:2017-07-02
  • Environmental life-cycle assessment
    Nature Mater. (IF 39.737) Pub Date : 
    Randolph E. Kirchain Jr, Jeremy R. Gregory, Elsa A. Olivetti

    Environmental life-cycle assessment Nature Materials, Published online: 27 June 2017; doi:10.1038/nmat4923 Concerns about the planet's health call for a careful evaluation of the environmental impact of materials choices. Life-cycle assessment is a tool that can help identify sustainable materials pathways by considering the burdens of materials both during production and as a product.

    更新日期:2017-07-02
  • Topological Kondo insulators: Negative pressure tuning
    Nature Mater. (IF 39.737) Pub Date : 
    Andrew P. Mackenzie, Clifford W. Hicks

    Topological Kondo insulators: Negative pressure tuning Nature Materials, Published online: 27 June 2017; doi:10.1038/nmat4925 Large tensile pressure applied to the putative topological Kondo insulator SmB6 results in an expansion of the lattice in all directions, and a huge increase in the temperature range over which surface-dominated conduction can be observed.

    更新日期:2017-07-02
  • Electrochemical strain microscopy probes morphology-induced variations in ion uptake and performance in organic electrochemical transistors
    Nature Mater. (IF 39.737) Pub Date : 2017-06-19
    R. Giridharagopal, L. Q. Flagg, J. S. Harrison, M. E. Ziffer, J. Onorato, C. K. Luscombe, D. S. Ginger

    Ionic transport phenomena in organic semiconductor materials underpin emerging technologies ranging from bioelectronics to energy storage. The performance of these systems is affected by an interplay of film morphology, ionic transport and electronic transport that is unique to organic semiconductors yet poorly understood. Using in situ electrochemical strain microscopy (ESM), we demonstrate that we can directly probe local variations in ion transport in polymer devices by measuring subnanometre volumetric expansion due to ion uptake following electrochemical oxidation of the semiconductor. The ESM data show that poly(3-hexylthiophene) electrochemical devices exhibit voltage-dependent heterogeneous swelling consistent with device operation and electrochromism. Our data show that polymer semiconductors can simultaneously exhibit field-effect and electrochemical operation regimes, with the operation modality and its distribution varying locally as a function of nanoscale film morphology, ion concentration and potential. Importantly, we provide a direct test of structure–function relationships by correlating strain heterogeneity with local stiffness maps. These data indicate that nanoscale variations in ion uptake are associated with local changes in polymer packing that may impede ion transport to different extents within the same macroscopic film and can inform future materials optimization.

    更新日期:2017-07-02
  • A sustainable material world
    Nature Mater. (IF 39.737) Pub Date : 2017-06-27

    By considering the environmental impact of materials through their whole life cycle, materials scientists can help develop more sustainable alternatives.

    更新日期:2017-07-01
  • Environmental life-cycle assessment
    Nature Mater. (IF 39.737) Pub Date : 2017-06-27
    Randolph E. Kirchain Jr, Jeremy R. Gregory, Elsa A. Olivetti

    Concerns about the planet's health call for a careful evaluation of the environmental impact of materials choices. Life-cycle assessment is a tool that can help identify sustainable materials pathways by considering the burdens of materials both during production and as a product.

    更新日期:2017-07-01
  • Towards sustainable concrete
    Nature Mater. (IF 39.737) Pub Date : 2017-06-27
    Paulo J. M. Monteiro, Sabbie A. Miller, Arpad Horvath

    Paulo J. M. Monteiro, Sabbie A. Miller and Arpad Horvath provide an overview of the challenges and accomplishments in reducing the environmental burden of concrete production.

    更新日期:2017-07-01
  • Playing with defects in metals
    Nature Mater. (IF 39.737) Pub Date : 2017-06-27
    Xiuyan Li, K. Lu

    Xiuyan Li and K. Lu discuss a strategy, alternative to alloying, to tailor the mechanical properties of metals. By engineering defects, metals with bespoke performance might be obtained while reducing the materials' compositional complexity.

    更新日期:2017-07-01
  • Topological Kondo insulators: Negative pressure tuning
    Nature Mater. (IF 39.737) Pub Date : 2017-06-27
    Andrew P. Mackenzie, Clifford W. Hicks

    Large tensile pressure applied to the putative topological Kondo insulator SmB6 results in an expansion of the lattice in all directions, and a huge increase in the temperature range over which surface-dominated conduction can be observed.

    更新日期:2017-07-01
  • Heterogeneous catalysis: Uniformity begets selectivity
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Dong Yang, Bruce C. Gates

    A Pd4 cluster, supported by a metal–organic framework and formed by post-synthesis methods, shows high catalytic activity and selectivity for carbene-mediated reactions. This crystallographically precise material may lead to a large class of catalysts.

    更新日期:2017-07-01
  • Semiconducting polymers: Probing the solid–liquid interface
    Nature Mater. (IF 39.737) Pub Date : 2017-06-19
    Xavier Crispin, Sergei V. Kalinin

    Exploring the minute mechanical deformations induced by electrical bias at the interface with electrolytes allows the identification of local crystallinity and distinguishing adsorption and intercalation of ions in electroactive polymers.

    更新日期:2017-07-01
  • Chalcogenide-based 2D materials: Intrinsic nanoscale patterning
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Joseph W. Lyding

    A method to realize regular patterns with nanometre precision during the synthesis of PtSe2 and CuSe monolayers has been developed.

    更新日期:2017-07-01
  • Surface-dominated conduction up to 240 K in the Kondo insulator SmB6 under strain
    Nature Mater. (IF 39.737) Pub Date : 2017-04-03
    A. Stern, M. Dzero, V. M. Galitski, Z. Fisk, J. Xia

    Surface-dominated conduction is found to dominate up to 240 K in the strongly correlated mixed-valence Kondo insulator SmB6 under the application of large strain.

    更新日期:2017-07-01
  • Electric field control of deterministic current-induced magnetization switching in a hybrid ferromagnetic/ferroelectric structure
    Nature Mater. (IF 39.737) Pub Date : 2017-04-03
    Kaiming Cai, Meiyin Yang, Hailang Ju, Sumei Wang, Yang Ji, Baohe Li, Kevin William Edmonds, Yu Sheng, Bao Zhang, Nan Zhang, Shuai Liu, Houzhi Zheng, Kaiyou Wang

    An electric field is shown to induce an in-plane effective magnetic field enabling the deterministic magnetization switching of a magnetic multilayer on a piezoelectric substrate.

    更新日期:2017-07-01
  • Intrinsically patterned two-dimensional materials for selective adsorption of molecules and nanoclusters
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    X. Lin, J. C. Lu, Y. Shao, Y. Y. Zhang, X. Wu, J. B. Pan, L. Gao, S. Y. Zhu, K. Qian, Y. F. Zhang, D. L. Bao, L. F. Li, Y. Q. Wang, Z. L. Liu, J. T. Sun, T. Lei, C. Liu, J. O. Wang, K. Ibrahim, D. N. Leonard, W. Zhou, H. M. Guo, Y. L. Wang, S. X. Du, S. T. Pantelides, H.-J. Gao

    PtSe2 and CuSe monolayers obtained by selenization of a metal substrate are shown to intrinsically form periodic patterns by varying the amount of Se atoms deposited. These patterns are used for the localized absorption of molecules and nanoclusters.

    更新日期:2017-07-01
  • Charge-transfer dynamics and nonlocal dielectric permittivity tuned with metamaterial structures as solvent analogues
    Nature Mater. (IF 39.737) Pub Date : 2017-06-05
    Kwang Jin Lee, Yiming Xiao, Jae Heun Woo, Eunsun Kim, David Kreher, André-Jean Attias, Fabrice Mathevet, Jean-Charles Ribierre, Jeong Weon Wu, Pascal André

    Charge transfer (CT) is a fundamental and ubiquitous mechanism in biology, physics and chemistry. Here, we evidence that CT dynamics can be altered by multi-layered hyperbolic metamaterial (HMM) substrates. Taking triphenylene:perylene diimide dyad supramolecular self-assemblies as a model system, we reveal longer-lived CT states in the presence of HMM structures, with both charge separation and recombination characteristic times increased by factors of 2.4 and 1.7—that is, relative variations of 140 and 73%, respectively. To rationalize these experimental results in terms of driving force, we successfully introduce image dipole interactions in Marcus theory. The non-local effect herein demonstrated is directly linked to the number of metal–dielectric pairs, can be formalized in the dielectric permittivity, and is presented as a solid analogue to local solvent polarity effects. This model and extra PH3T:PC60BM results show the generality of this non-local phenomenon and that a wide range of kinetic tailoring opportunities can arise from substrate engineering. This work paves the way toward the design of artificial substrates to control CT dynamics of interest for applications in optoelectronics and chemistry.

    更新日期:2017-07-01
  • Cast aluminium single crystals cross the threshold from bulk to size-dependent stochastic plasticity
    Nature Mater. (IF 39.737) Pub Date : 2017-05-29
    J. Krebs, S. I. Rao, S. Verheyden, C. Miko, R. Goodall, W. A. Curtin, A. Mortensen

    Metals are known to exhibit mechanical behaviour at the nanoscale different to bulk samples. This transition typically initiates at the micrometre scale, yet existing techniques to produce micrometre-sized samples often introduce artefacts that can influence deformation mechanisms. Here, we demonstrate the casting of micrometre-scale aluminium single-crystal wires by infiltration of a salt mould. Samples have millimetre lengths, smooth surfaces, a range of crystallographic orientations, and a diameter D as small as 6 μm. The wires deform in bursts, at a stress that increases with decreasing D. Bursts greater than 200 nm account for roughly 50% of wire deformation and have exponentially distributed intensities. Dislocation dynamics simulations show that single-arm sources that produce large displacement bursts halted by stochastic cross-slip and lock formation explain microcast wire behaviour. This microcasting technique may be extended to several other metals or alloys and offers the possibility of exploring mechanical behaviour spanning the micrometre scale.

    更新日期:2017-07-01
  • Electrochemical strain microscopy probes morphology-induced variations in ion uptake and performance in organic electrochemical transistors
    Nature Mater. (IF 39.737) Pub Date : 2017-06-19
    R. Giridharagopal, L. Q. Flagg, J. S. Harrison, M. E. Ziffer, J. Onorato, C. K. Luscombe, D. S. Ginger

    Ionic transport phenomena in organic semiconductor materials underpin emerging technologies ranging from bioelectronics to energy storage. The performance of these systems is affected by an interplay of film morphology, ionic transport and electronic transport that is unique to organic semiconductors yet poorly understood. Using in situ electrochemical strain microscopy (ESM), we demonstrate that we can directly probe local variations in ion transport in polymer devices by measuring subnanometre volumetric expansion due to ion uptake following electrochemical oxidation of the semiconductor. The ESM data show that poly(3-hexylthiophene) electrochemical devices exhibit voltage-dependent heterogeneous swelling consistent with device operation and electrochromism. Our data show that polymer semiconductors can simultaneously exhibit field-effect and electrochemical operation regimes, with the operation modality and its distribution varying locally as a function of nanoscale film morphology, ion concentration and potential. Importantly, we provide a direct test of structure–function relationships by correlating strain heterogeneity with local stiffness maps. These data indicate that nanoscale variations in ion uptake are associated with local changes in polymer packing that may impede ion transport to different extents within the same macroscopic film and can inform future materials optimization.

    更新日期:2017-07-01
  • An intrinsic growth instability in isotropic materials leads to quasi-two-dimensional nanoplatelets
    Nature Mater. (IF 39.737) Pub Date : 2017-04-03
    Andreas Riedinger, Florian D. Ott, Aniket Mule, Sergio Mazzotti, Philippe N. Knüsel, Stephan J. P. Kress, Ferry Prins, Steven C. Erwin, David J. Norris

    Colloidal nanoplatelets are atomically flat, quasi-two-dimensional sheets of semiconductor that can exhibit efficient, spectrally pure fluorescence. Despite intense interest in their properties, the mechanism behind their highly anisotropic shape and precise atomic-scale thickness remains unclear, and even counter-intuitive for commonly studied nanoplatelets that arise from isotropic crystal structures (such as zincblende CdSe and lead halide perovskites). Here we show that an intrinsic instability in growth kinetics can lead to such highly anisotropic shapes. By combining experimental results on the synthesis of CdSe nanoplatelets with theory predicting enhanced growth on narrow surface facets, we develop a model that explains nanoplatelet formation as well as observed dependencies on time and temperature. Based on standard concepts of volume, surface and edge energies, the resulting growth instability criterion can be directly applied to other crystalline materials. Thus, knowledge of this previously unknown mechanism for controlling shape at the nanoscale can lead to broader libraries of quasi-two-dimensional materials.

    更新日期:2017-07-01
  • Dynamic chemical expansion of thin-film non-stoichiometric oxides at extreme temperatures
    Nature Mater. (IF 39.737) Pub Date : 2017-05-08
    Jessica G. Swallow, Jae Jin Kim, John M. Maloney, Di Chen, James F. Smith, Sean R. Bishop, Harry L. Tuller, Krystyn J. Van Vliet

    Actuator operation in increasingly extreme and remote conditions requires materials that reliably sense and actuate at elevated temperatures, and over a range of gas environments. Design of such materials will rely on high-temperature, high-resolution approaches for characterizing material actuation in situ. Here, we demonstrate a novel type of high-temperature, low-voltage electromechanical oxide actuator based on the model material PrxCe1−xO2−δ (PCO). Chemical strain and interfacial stress resulted from electrochemically pumping oxygen into or out of PCO films, leading to measurable film volume changes due to chemical expansion. At 650 °C, nanometre-scale displacement and strain of >0.1% were achieved with electrical bias values <0.1 V, low compared to piezoelectrically driven actuators, with strain amplified fivefold by stress-induced structural deflection. This operando measurement of films ‘breathing’ at second-scale temporal resolution also enabled detailed identification of the controlling kinetics of this response, and can be extended to other electrochemomechanically coupled oxide films at extreme temperatures.

    更新日期:2017-07-01
  • Electron crystallography for determining the handedness of a chiral zeolite nanocrystal
    Nature Mater. (IF 39.737) Pub Date : 2017-05-01
    Yanhang Ma, Peter Oleynikov, Osamu Terasaki

    Chiral crystals can be exploited for applications in enantioselective separation and catalysis. However, the study of chirality at the atomic level in a sub-micrometre-sized crystal is difficult due to the lack of adequate characterization methods. Herein, we present two efficient and practical methods of characterization that are based on electron crystallography. These methods are successfully applied to reveal the handedness of a chiral, zeolite nanocrystal. The handedness is identified through either a comparison of two high-resolution transmission electron microscope images, taken from the same nanocrystal but along different zone axes by tilting it around its screw axis, or the intensity asymmetry of a Bijvoet pair of reflections in a single precession electron-diffraction pattern. These two approaches provide new ways to determine the handedness of small, chiral crystals.

    更新日期:2017-07-01
  • The MOF-driven synthesis of supported palladium clusters with catalytic activity for carbene-mediated chemistry
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Francisco R. Fortea-Pérez, Marta Mon, Jesús Ferrando-Soria, Mercedes Boronat, Antonio Leyva-Pérez, Avelino Corma, Juan Manuel Herrera, Dmitrii Osadchii, Jorge Gascon, Donatella Armentano, Emilio Pardo

    The development of catalysts able to assist industrially important chemical processes is a topic of high importance. In view of the catalytic capabilities of small metal clusters, research efforts are being focused on the synthesis of novel catalysts bearing such active sites. Here we report a heterogeneous catalyst consisting of Pd4 clusters with mixed-valence 0/+1 oxidation states, stabilized and homogeneously organized within the walls of a metal–organic framework (MOF). The resulting solid catalyst outperforms state-of-the-art metal catalysts in carbene-mediated reactions of diazoacetates, with high yields (>90%) and turnover numbers (up to 100,000). In addition, the MOF-supported Pd4 clusters retain their catalytic activity in repeated batch and flow reactions (>20 cycles). Our findings demonstrate how this synthetic approach may now instruct the future design of heterogeneous catalysts with advantageous reaction capabilities for other important processes.

    更新日期:2017-07-01
  • Tuning crystallization pathways through sequence engineering of biomimetic polymers
    Nature Mater. (IF 39.737) Pub Date : 2017-04-17
    Xiang Ma, Shuai Zhang, Fang Jiao, Christina J. Newcomb, Yuliang Zhang, Arushi Prakash, Zhihao Liao, Marcel D. Baer, Christopher J. Mundy, James Pfaendtner, Aleksandr Noy, Chun-Long Chen, James J. De Yoreo

    Two-step nucleation pathways in which disordered, amorphous, or dense liquid states precede the appearance of crystalline phases have been reported for a wide range of materials, but the dynamics of such pathways are poorly understood. Moreover, whether these pathways are general features of crystallizing systems or a consequence of system-specific structural details that select for direct versus two-step processes is unknown. Using atomic force microscopy to directly observe crystallization of sequence-defined polymers, we show that crystallization pathways are indeed sequence dependent. When a short hydrophobic region is added to a sequence that directly forms crystalline particles, crystallization instead follows a two-step pathway that begins with the creation of disordered clusters of 10–20 molecules and is characterized by highly non-linear crystallization kinetics in which clusters transform into ordered structures that then enter the growth phase. The results shed new light on non-classical crystallization mechanisms and have implications for the design of self-assembling polymer systems.

    更新日期:2017-07-01
  • EGFR and HER2 activate rigidity sensing only on rigid matrices
    Nature Mater. (IF 39.737) Pub Date : 2017-05-01
    Mayur Saxena, Shuaimin Liu, Bo Yang, Cynthia Hajal, Rishita Changede, Junqiang Hu, Haguy Wolfenson, James Hone, Michael P. Sheetz

    Epidermal growth factor receptor (EGFR) interacts with integrins during cell spreading and motility, but little is known about the role of EGFR in these mechanosensing processes. Here we show, using two different cell lines, that in serum- and EGF-free conditions, EGFR or HER2 activity increase spreading and rigidity-sensing contractions on rigid, but not soft, substrates. Contractions peak after 15–20 min, but diminish by tenfold after 4 h. Addition of EGF at that point increases spreading and contractions, but this can be blocked by myosin-II inhibition. We further show that EGFR and HER2 are activated through phosphorylation by Src family kinases (SFK). On soft surfaces, neither EGFR inhibition nor EGF stimulation have any effect on cell motility. Thus, EGFR or HER2 can catalyse rigidity sensing after associating with nascent adhesions under rigidity-dependent tension downstream of SFK activity. This has broad implications for the roles of EGFR and HER2 in the absence of EGF both for normal and cancerous growth.

    更新日期:2017-07-01
  • Semiconducting polymers: Probing the solid–liquid interface
    Nature Mater. (IF 39.737) Pub Date : 2017-06-19
    Xavier Crispin, Sergei V. Kalinin

    Exploring the minute mechanical deformations induced by electrical bias at the interface with electrolytes allows the identification of local crystallinity and distinguishing adsorption and intercalation of ions in electroactive polymers.

    更新日期:2017-07-01
  • Chalcogenide-based 2D materials: Intrinsic nanoscale patterning
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Joseph W. Lyding

    A method to realize regular patterns with nanometre precision during the synthesis of PtSe2 and CuSe monolayers has been developed.

    更新日期:2017-07-01
  • Intrinsically patterned two-dimensional materials for selective adsorption of molecules and nanoclusters
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    X. Lin, J. C. Lu, Y. Shao, Y. Y. Zhang, X. Wu, J. B. Pan, L. Gao, S. Y. Zhu, K. Qian, Y. F. Zhang, D. L. Bao, L. F. Li, Y. Q. Wang, Z. L. Liu, J. T. Sun, T. Lei, C. Liu, J. O. Wang, K. Ibrahim, D. N. Leonard, W. Zhou, H. M. Guo, Y. L. Wang, S. X. Du, S. T. Pantelides, H.-J. Gao

    PtSe2 and CuSe monolayers obtained by selenization of a metal substrate are shown to intrinsically form periodic patterns by varying the amount of Se atoms deposited. These patterns are used for the localized absorption of molecules and nanoclusters.

    更新日期:2017-07-01
  • Heterogeneous catalysis: Uniformity begets selectivity
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Dong Yang, Bruce C. Gates

    A Pd4 cluster, supported by a metal–organic framework and formed by post-synthesis methods, shows high catalytic activity and selectivity for carbene-mediated reactions. This crystallographically precise material may lead to a large class of catalysts.

    更新日期:2017-07-01
  • Emergence of an enslaved phononic bandgap in a non-equilibrium pseudo-crystal
    Nature Mater. (IF 39.737) Pub Date : 2017-06-19
    Nicolas Bachelard, Chad Ropp, Marc Dubois, Rongkuo Zhao, Yuan Wang, Xiang Zhang

    Material systems that reside far from thermodynamic equilibrium have the potential to exhibit dynamic properties and behaviours resembling those of living organisms. Here we realize a non-equilibrium material characterized by a bandgap whose edge is enslaved to the wavelength of an external coherent drive. The structure dynamically self-assembles into an unconventional pseudo-crystal geometry that equally distributes momentum across elements. The emergent bandgap is bestowed with lifelike properties, such as the ability to self-heal to perturbations and adapt to sudden changes in the drive. We derive an exact analytical solution for both the spatial organization and the bandgap features, revealing the mechanism for enslavement. This work presents a framework for conceiving lifelike non-equilibrium materials and emphasizes the potential for the dynamic imprinting of material properties through external degrees of freedom.

    更新日期:2017-07-01
  • Universal quinone electrodes for long cycle life aqueous rechargeable batteries
    Nature Mater. (IF 39.737) Pub Date : 2017-06-19
    Yanliang Liang, Yan Jing, Saman Gheytani, Kuan-Yi Lee, Ping Liu, Antonio Facchetti, Yan Yao

    Aqueous rechargeable batteries provide the safety, robustness, affordability, and environmental friendliness necessary for grid storage and electric vehicle operations, but their adoption is plagued by poor cycle life due to the structural and chemical instability of the anode materials. Here we report quinones as stable anode materials by exploiting their structurally stable ion-coordination charge storage mechanism and chemical inertness towards aqueous electrolytes. Upon rational selection/design of quinone structures, we demonstrate three systems that coupled with industrially established cathodes and electrolytes exhibit long cycle life (up to 3,000 cycles/3,500 h), fast kinetics (≥20C), high anode specific capacity (up to 200–395 mAh g−1), and several examples of state-of-the-art specific energy/energy density (up to 76–92 Wh kg−1/ 161–208 Wh l−1) for several operational pH values (−1 to 15), charge carrier species (H+, Li+, Na+, K+, Mg2+), temperature (−35 to 25 °C), and atmosphere (with/without O2), making them a universal anode approach for any aqueous battery technology.

    更新日期:2017-07-01
  • The MOF-driven synthesis of supported palladium clusters with catalytic activity for carbene-mediated chemistry
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Francisco R. Fortea-Pérez, Marta Mon, Jesús Ferrando-Soria, Mercedes Boronat, Antonio Leyva-Pérez, Avelino Corma, Juan Manuel Herrera, Dmitrii Osadchii, Jorge Gascon, Donatella Armentano, Emilio Pardo

    The development of catalysts able to assist industrially important chemical processes is a topic of high importance. In view of the catalytic capabilities of small metal clusters, research efforts are being focused on the synthesis of novel catalysts bearing such active sites. Here we report a heterogeneous catalyst consisting of Pd4 clusters with mixed-valence 0/+1 oxidation states, stabilized and homogeneously organized within the walls of a metal–organic framework (MOF). The resulting solid catalyst outperforms state-of-the-art metal catalysts in carbene-mediated reactions of diazoacetates, with high yields (>90%) and turnover numbers (up to 100,000). In addition, the MOF-supported Pd4 clusters retain their catalytic activity in repeated batch and flow reactions (>20 cycles). Our findings demonstrate how this synthetic approach may now instruct the future design of heterogeneous catalysts with advantageous reaction capabilities for other important processes.

    更新日期:2017-07-01
  • Tension stimulation drives tissue formation in scaffold-free systems
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Jennifer K. Lee, Le W. Huwe, Nikolaos Paschos, Ashkan Aryaei, Courtney A. Gegg, Jerry C. Hu, Kyriacos A. Athanasiou

    Scaffold-free systems have emerged as viable approaches for engineering load-bearing tissues. However, the tensile properties of engineered tissues have remained far below the values for native tissue. Here, by using self-assembled articular cartilage as a model to examine the effects of intermittent and continuous tension stimulation on tissue formation, we show that the application of tension alone, or in combination with matrix remodelling and synthesis agents, leads to neocartilage with tensile properties approaching those of native tissue. Implantation of tension-stimulated tissues results in neotissues that are morphologically reminiscent of native cartilage. We also show that tension stimulation can be translated to a human cell source to generate anisotropic human neocartilage with enhanced tensile properties. Tension stimulation, which results in nearly sixfold improvements in tensile properties over unstimulated controls, may allow the engineering of mechanically robust biological replacements of native tissue.

    更新日期:2017-07-01
  • Phagocytosis-inspired behaviour in synthetic protocell communities of compartmentalized colloidal objects
    Nature Mater. (IF 39.737) Pub Date : 2017-06-12
    Laura Rodríguez-Arco, Mei Li, Stephen Mann

    The spontaneous assembly of micro-compartmentalized colloidal objects capable of controlled interactions offers a step towards rudimentary forms of collective behaviour in communities of artificial cell-like entities (synthetic protocells). Here we report a primitive form of artificial phagocytosis in a binary community of synthetic protocells in which multiple silica colloidosomes are selectively ingested by self-propelled magnetic Pickering emulsion (MPE) droplets comprising particle-free fatty acid-stabilized apertures. Engulfment of the colloidosomes enables selective delivery and release of water-soluble payloads, and can be coupled to enzyme activity within the MPE droplets. Our results highlight opportunities for the development of new materials based on consortia of colloidal objects, and provide a novel microscale engineering approach to inducing higher-order behaviour in mixed populations of synthetic protocells.

    更新日期:2017-07-01
  • Charge-transfer dynamics and nonlocal dielectric permittivity tuned with metamaterial structures as solvent analogues
    Nature Mater. (IF 39.737) Pub Date : 2017-06-05

    Charge transfer (CT) is a fundamental and ubiquitous mechanism in biology, physics and chemistry. Here, we evidence that CT dynamics can be altered by multi-layered hyperbolic metamaterial (HMM) substrates. Taking triphenylene:perylene diimide dyad supramolecular self-assemblies as a model system, we reveal longer-lived CT states in the presence of HMM structures, with both charge separation and recombination characteristic times increased by factors of 2.4 and 1.7—that is, relative variations of 140 and 73%, respectively. To rationalize these experimental results in terms of driving force, we successfully introduce image dipole interactions in Marcus theory. The non-local effect herein demonstrated is directly linked to the number of metal–dielectric pairs, can be formalized in the dielectric permittivity, and is presented as a solid analogue to local solvent polarity effects. This model and extra PH3T:PC60BM results show the generality of this non-local phenomenon and that a wide range of kinetic tailoring opportunities can arise from substrate engineering. This work paves the way toward the design of artificial substrates to control CT dynamics of interest for applications in optoelectronics and chemistry.

    更新日期:2017-07-01
  • Cast aluminium single crystals cross the threshold from bulk to size-dependent stochastic plasticity
    Nature Mater. (IF 39.737) Pub Date : 2017-05-29
    J. Krebs, S. I. Rao, S. Verheyden, C. Miko, R. Goodall, W. A. Curtin, A. Mortensen

    Metals are known to exhibit mechanical behaviour at the nanoscale different to bulk samples. This transition typically initiates at the micrometre scale, yet existing techniques to produce micrometre-sized samples often introduce artefacts that can influence deformation mechanisms. Here, we demonstrate the casting of micrometre-scale aluminium single-crystal wires by infiltration of a salt mould. Samples have millimetre lengths, smooth surfaces, a range of crystallographic orientations, and a diameter D as small as 6 μm. The wires deform in bursts, at a stress that increases with decreasing D. Bursts greater than 200 nm account for roughly 50% of wire deformation and have exponentially distributed intensities. Dislocation dynamics simulations show that single-arm sources that produce large displacement bursts halted by stochastic cross-slip and lock formation explain microcast wire behaviour. This microcasting technique may be extended to several other metals or alloys and offers the possibility of exploring mechanical behaviour spanning the micrometre scale.

    更新日期:2017-07-01
  • Molecular engineering of chiral colloidal liquid crystals using DNA origami
    Nature Mater. (IF 39.737) Pub Date : 2017-05-22
    Mahsa Siavashpouri, Christian H. Wachauf, Mark J. Zakhary, Florian Praetorius, Hendrik Dietz, Zvonimir Dogic

    Establishing precise control over the shape and the interactions of the microscopic building blocks is essential for design of macroscopic soft materials with novel structural, optical and mechanical properties. Here, we demonstrate robust assembly of DNA origami filaments into cholesteric liquid crystals, one-dimensional supramolecular twisted ribbons and two-dimensional colloidal membranes. The exquisite control afforded by the DNA origami technology establishes a quantitative relationship between the microscopic filament structure and the macroscopic cholesteric pitch. Furthermore, it also enables robust assembly of one-dimensional twisted ribbons, which behave as effective supramolecular polymers whose structure and elastic properties can be precisely tuned by controlling the geometry of the elemental building blocks. Our results demonstrate the potential synergy between DNA origami technology and colloidal science, in which the former allows for rapid and robust synthesis of complex particles, and the latter can be used to assemble such particles into bulk materials.

    更新日期:2017-07-01
  • Produce and use with care
    Nature Mater. (IF 39.737) Pub Date : 2017-06-27

    更新日期:2017-06-28
  • Material Witness: Making anyon soup
    Nature Mater. (IF 39.737) Pub Date : 2017-06-27
    Philip Ball

    更新日期:2017-06-28
  • Direct 3D mapping of the Fermi surface and Fermi velocity
    Nature Mater. (IF 39.737) Pub Date : 2017-03-13
    K. Medjanik, O. Fedchenko, S. Chernov, D. Kutnyakhov, M. Ellguth, A. Oelsner, B. Schönhense, T. R. F. Peixoto, P. Lutz, C.-H. Min, F. Reinert, S. Däster, Y. Acremann, J. Viefhaus, W. Wurth, H. J. Elmers, G. Schönhense

    We performed a full mapping of the bulk electronic structure including the Fermi surface and Fermi-velocity distribution vF(kF) of tungsten. The 4D spectral function ρ(EB; k) in the entire bulk Brillouin zone and 6 eV binding-energy (EB) interval was acquired in ~3 h thanks to a new multidimensional photoemission data-recording technique (combining full-field k-microscopy with time-of-flight parallel energy recording) and the high brilliance of the soft X-rays used. A direct comparison of bulk and surface spectral functions (taken at low photon energies) reveals a time-reversal-invariant surface state in a local bandgap in the (110)-projected bulk band structure. The surface state connects hole and electron pockets that would otherwise be separated by an indirect local bandgap. We confirmed its Dirac-like spin texture by spin-filtered momentum imaging. The measured 4D data array enables extraction of the 3D dispersion of all bands, all energy isosurfaces, electron velocities, hole or electron conductivity, effective mass and inner potential by simple algorithms without approximations. The high-Z bcc metals with large spin–orbit-induced bandgaps are discussed as candidates for topologically non-trivial surface states.

    更新日期:2017-05-29
  • Photoelectrochemical water splitting in separate oxygen and hydrogen cells
    Nature Mater. (IF 39.737) Pub Date : 2017-03-13
    Avigail Landman, Hen Dotan, Gennady E. Shter, Michael Wullenkord, Anis Houaijia, Artjom Maljusch, Gideon S. Grader, Avner Rothschild

    Solar water splitting provides a promising path for sustainable hydrogen production and solar energy storage. One of the greatest challenges towards large-scale utilization of this technology is reducing the hydrogen production cost. The conventional electrolyser architecture, where hydrogen and oxygen are co-produced in the same cell, gives rise to critical challenges in photoelectrochemical water splitting cells that directly convert solar energy and water to hydrogen. Here we overcome these challenges by separating the hydrogen and oxygen cells. The ion exchange in our cells is mediated by auxiliary electrodes, and the cells are connected to each other only by metal wires, enabling centralized hydrogen production. We demonstrate hydrogen generation in separate cells with solar-to-hydrogen conversion efficiency of 7.5%, which can readily surpass 10% using standard commercial components. A basic cost comparison shows that our approach is competitive with conventional photoelectrochemical systems, enabling safe and potentially affordable solar hydrogen production.

    更新日期:2017-05-29
  • Controlling the growth of multiple ordered heteromolecular phases by utilizing intermolecular repulsion
    Nature Mater. (IF 39.737) Pub Date : 2017-03-13
    Caroline Henneke, Janina Felter, Daniel Schwarz, F. Stefan Tautz, Christian Kumpf

    Metal/organic interfaces and their structural, electronic, spintronic and thermodynamic properties have been investigated intensively, aiming to improve and develop future electronic devices. In this context, heteromolecular phases add new design opportunities simply by combining different molecules. However, controlling the desired phases in such complex systems is a challenging task. Here, we report an effective way of steering the growth of a bimolecular system composed of adsorbate species with opposite intermolecular interactions—repulsive and attractive, respectively. The repulsive species forms a two-dimensional lattice gas, the density of which controls which crystalline phases are stable. Critical gas phase densities determine the constant-area phase diagram that describes our experimental observations, including eutectic regions with three coexisting phases. We anticipate the general validity of this type of phase diagram for binary systems containing two-dimensional gas phases, and also show that the density of the gas phase allows engineering of the interface structure.

    更新日期:2017-05-29
  • Colony stimulating factor-1 receptor is a central component of the foreign body response to biomaterial implants in rodents and non-human primates
    Nature Mater. (IF 39.737) Pub Date : 2017-03-20
    Joshua C. Doloff, Omid Veiseh, Arturo J. Vegas, Hok Hei Tam, Shady Farah, Minglin Ma, Jie Li, Andrew Bader, Alan Chiu, Atieh Sadraei, Stephanie Aresta-Dasilva, Marissa Griffin, Siddharth Jhunjhunwala, Matthew Webber, Sean Siebert, Katherine Tang, Michael Chen, Erin Langan, Nimit Dholokia, Raj Thakrar, Meirigeng Qi, Jose Oberholzer, Dale L. Greiner, Robert Langer, Daniel G. Anderson

    Host recognition and immune-mediated foreign body response to biomaterials can compromise the performance of implanted medical devices. To identify key cell and cytokine targets, here we perform in-depth systems analysis of innate and adaptive immune system responses to implanted biomaterials in rodents and non-human primates. While macrophages are indispensable to the fibrotic cascade, surprisingly neutrophils and complement are not. Macrophages, via CXCL13, lead to downstream B cell recruitment, which further potentiated fibrosis, as confirmed by B cell knockout and CXCL13 neutralization. Interestingly, colony stimulating factor-1 receptor (CSF1R) is significantly increased following implantation of multiple biomaterial classes: ceramic, polymer and hydrogel. Its inhibition, like macrophage depletion, leads to complete loss of fibrosis, but spares other macrophage functions such as wound healing, reactive oxygen species production and phagocytosis. Our results indicate that targeting CSF1R may allow for a more selective method of fibrosis inhibition, and improve biomaterial biocompatibility without the need for broad immunosuppression.

    更新日期:2017-05-29
  • Synthesis of Ti3AuC2, Ti3Au2C2 and Ti3IrC2 by noble metal substitution reaction in Ti3SiC2 for high-temperature-stable Ohmic contacts to SiC
    Nature Mater. (IF 39.737) Pub Date : 2017-05-01
    Hossein Fashandi, Martin Dahlqvist, Jun Lu, Justinas Palisaitis, Sergei I. Simak, Igor A. Abrikosov, Johanna Rosen, Lars Hultman, Mike Andersson, Anita Lloyd Spetz, Per Eklund

    The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored. Here, we show formation of Ti3AuC2 and Ti3Au2C2 phases with up to 31% lattice swelling by a substitutional solid-state reaction of Au into Ti3SiC2 single-crystal thin films with simultaneous out-diffusion of Si. Ti3IrC2 is subsequently produced by a substitution reaction of Ir for Au in Ti3Au2C2. These phases form Ohmic electrical contacts to SiC and remain stable after 1,000 h of ageing at 600 °C in air. The present results, by combined analytical electron microscopy and ab initio calculations, open avenues for processing of noble-metal-containing layered ceramics that have not been synthesized from elemental sources, along with tunable properties such as stable electrical contacts for high-temperature power electronics or gas sensors.

    更新日期:2017-05-29
  • Dynamic chemical expansion of thin-film non-stoichiometric oxides at extreme temperatures
    Nature Mater. (IF 39.737) Pub Date : 2017-05-08
    Jessica G. Swallow, Jae Jin Kim, John M. Maloney, Di Chen, James F. Smith, Sean R. Bishop, Harry L. Tuller, Krystyn J. Van Vliet

    Actuator operation in increasingly extreme and remote conditions requires materials that reliably sense and actuate at elevated temperatures, and over a range of gas environments. Design of such materials will rely on high-temperature, high-resolution approaches for characterizing material actuation in situ. Here, we demonstrate a novel type of high-temperature, low-voltage electromechanical oxide actuator based on the model material PrxCe1−xO2−δ (PCO). Chemical strain and interfacial stress resulted from electrochemically pumping oxygen into or out of PCO films, leading to measurable film volume changes due to chemical expansion. At 650 °C, nanometre-scale displacement and strain of >0.1% were achieved with electrical bias values <0.1 V, low compared to piezoelectrically driven actuators, with strain amplified fivefold by stress-induced structural deflection. This operando measurement of films ‘breathing’ at second-scale temporal resolution also enabled detailed identification of the controlling kinetics of this response, and can be extended to other electrochemomechanically coupled oxide films at extreme temperatures.

    更新日期:2017-05-29
  • Multi-stimuli manipulation of antiferromagnetic domains assessed by second-harmonic imaging
    Nature Mater. (IF 39.737) Pub Date : 2017-05-08
    J.-Y. Chauleau, E. Haltz, C. Carrétéro, S. Fusil, M. Viret

    Sub-coercive electric fields and sub-picosecond light pulses are shown to enable low-power manipulation of antiferromagnetic domains in the multiferroic BiFeO3.

    更新日期:2017-05-29
  • Heteromolecular phases: Opposite interaction matters
    Nature Mater. (IF 39.737) Pub Date : 2017-03-13
    Christian Teichert

    Low-energy electron microscopy reveals how growth of multiple ordered heteromolecular phases can be steered by utilizing intermolecular repulsion.

    更新日期:2017-05-29
  • Colony stimulating factor-1 receptor is a central component of the foreign body response to biomaterial implants in rodents and non-human primates
    Nature Mater. (IF 39.737) Pub Date : 2017-03-20
    Joshua C. Doloff, Omid Veiseh, Arturo J. Vegas, Hok Hei Tam, Shady Farah, Minglin Ma, Jie Li, Andrew Bader, Alan Chiu, Atieh Sadraei, Stephanie Aresta-Dasilva, Marissa Griffin, Siddharth Jhunjhunwala, Matthew Webber, Sean Siebert, Katherine Tang, Michael Chen, Erin Langan, Nimit Dholokia, Raj Thakrar, Meirigeng Qi, Jose Oberholzer, Dale L. Greiner, Robert Langer, Daniel G. Anderson

    Host recognition and immune-mediated foreign body response to biomaterials can compromise the performance of implanted medical devices. To identify key cell and cytokine targets, here we perform in-depth systems analysis of innate and adaptive immune system responses to implanted biomaterials in rodents and non-human primates. While macrophages are indispensable to the fibrotic cascade, surprisingly neutrophils and complement are not. Macrophages, via CXCL13, lead to downstream B cell recruitment, which further potentiated fibrosis, as confirmed by B cell knockout and CXCL13 neutralization. Interestingly, colony stimulating factor-1 receptor (CSF1R) is significantly increased following implantation of multiple biomaterial classes: ceramic, polymer and hydrogel. Its inhibition, like macrophage depletion, leads to complete loss of fibrosis, but spares other macrophage functions such as wound healing, reactive oxygen species production and phagocytosis. Our results indicate that targeting CSF1R may allow for a more selective method of fibrosis inhibition, and improve biomaterial biocompatibility without the need for broad immunosuppression.

    更新日期:2017-05-29
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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