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  • Large anomalous Hall current induced by topological nodal lines in a ferromagnetic van der Waals semimetal
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-16
    Kyoo Kim, Junho Seo, Eunwoo Lee, K.-T. Ko, B. S. Kim, Bo Gyu Jang, Jong Mok Ok, Jinwon Lee, Youn Jung Jo, Woun Kang, Ji Hoon Shim, C. Kim, Han Woong Yeom, Byung Il Min, Bohm-Jung Yang, Jun Sung Kim

    Topological semimetals host electronic structures with several band-contact points or lines and are generally expected to exhibit strong topological responses. Up to now, most work has been limited to non-magnetic materials and the interplay between topology and magnetism in this class of quantum materials has been largely unexplored. Here we utilize theoretical calculations, magnetotransport and angle-resolved photoemission spectroscopy to propose Fe3GeTe2, a van der Waals material, as a candidate ferromagnetic (FM) nodal line semimetal. We find that the spin degree of freedom is fully quenched by the large FM polarization, but the line degeneracy is protected by crystalline symmetries that connect two orbitals in adjacent layers. This orbital-driven nodal line is tunable by spin orientation due to spin–orbit coupling and produces a large Berry curvature, which leads to a large anomalous Hall current, angle and factor. These results demonstrate that FM topological semimetals hold significant potential for spin- and orbital-dependent electronic functionalities.

    更新日期:2018-07-18
  • Structural evolution of titanium dioxide during reduction in high-pressure hydrogen
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-16
    Sencer Selcuk, Xunhua Zhao, Annabella Selloni

    The excellent photocatalytic properties of titanium oxide (TiO2) under ultraviolet light have long motivated the search for doping strategies capable of extending its photoactivity to the visible part of the spectrum. One approach is high-pressure and high-temperature hydrogenation, which results in reduced ‘black TiO2’ nanoparticles with a crystalline core and a disordered shell that absorbs visible light. Here we elucidate the formation mechanism and structural features of black TiO2 using first-principles-validated reactive force field molecular dynamics simulations of anatase TiO2 surfaces and nanoparticles at high temperature and under high hydrogen pressures. Simulations reveal that surface oxygen vacancies created upon reaction of H2 with surface oxygen atoms diffuse towards the bulk material but encounter a high barrier for subsurface migration on {001} facets of the nanoparticles, which initiates surface disordering. Besides confirming that the hydrogenated amorphous shell has a key role in the photoactivity of black TiO2, our results provide insight into the properties of the disordered surface layers that are observed on regular anatase nanocrystals under photocatalytic water-splitting conditions.

    更新日期:2018-07-18
  • Design rules for minimizing voltage losses in high-efficiency organic solar cells
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-16
    Deping Qian, Zilong Zheng, Huifeng Yao, Wolfgang Tress, Thomas R. Hopper, Shula Chen, Sunsun Li, Jing Liu, Shangshang Chen, Jiangbin Zhang, Xiao-Ke Liu, Bowei Gao, Liangqi Ouyang, Yingzhi Jin, Galia Pozina, Irina A. Buyanova, Weimin M. Chen, Olle Inganäs, Veaceslav Coropceanu, Jean-Luc Bredas, He Yan, Jianhui Hou, Fengling Zhang, Artem A. Bakulin, Feng Gao

    The open-circuit voltage of organic solar cells is usually lower than the values achieved in inorganic or perovskite photovoltaic devices with comparable bandgaps. Energy losses during charge separation at the donor–acceptor interface and non-radiative recombination are among the main causes of such voltage losses. Here we combine spectroscopic and quantum-chemistry approaches to identify key rules for minimizing voltage losses: (1) a low energy offset between donor and acceptor molecular states and (2) high photoluminescence yield of the low-gap material in the blend. Following these rules, we present a range of existing and new donor–acceptor systems that combine efficient photocurrent generation with electroluminescence yield up to 0.03%, leading to non-radiative voltage losses as small as 0.21 V. This study provides a rationale to explain and further improve the performance of recently demonstrated high-open-circuit-voltage organic solar cells.

    更新日期:2018-07-18
  • Surface distortion as a unifying concept and descriptor in oxygen reduction reaction electrocatalysis
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-16
    Raphaël Chattot, Olivier Le Bacq, Vera Beermann, Stefanie Kühl, Juan Herranz, Sebastian Henning, Laura Kühn, Tristan Asset, Laure Guétaz, Gilles Renou, Jakub Drnec, Pierre Bordet, Alain Pasturel, Alexander Eychmüller, Thomas J. Schmidt, Peter Strasser, Laetitia Dubau, Frédéric Maillard

    Tuning the surface structure at the atomic level is of primary importance to simultaneously meet the electrocatalytic performance and stability criteria required for the development of low-temperature proton-exchange membrane fuel cells (PEMFCs). However, transposing the knowledge acquired on extended, model surfaces to practical nanomaterials remains highly challenging. Here, we propose ‘surface distortion’ as a novel structural descriptor, which is able to reconciliate and unify seemingly opposing notions and contradictory experimental observations in regards to the electrocatalytic oxygen reduction reaction (ORR) reactivity. Beyond its unifying character, we show that surface distortion is pivotal to rationalize the electrocatalytic properties of state-of-the-art of PtNi/C nanocatalysts with distinct atomic composition, size, shape and degree of surface defectiveness under a simulated PEMFC cathode environment. Our study brings fundamental and practical insights into the role of surface defects in electrocatalysis and highlights strategies to design more durable ORR nanocatalysts.

    更新日期:2018-07-18
  • Intermixing and periodic self-assembly of borophene line defects
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-16
    Xiaolong Liu, Zhuhua Zhang, Luqing Wang, Boris I. Yakobson, Mark C. Hersam

    Two-dimensional (2D) boron (that is, borophene) was recently synthesized following theoretical predictions1,2,3,4,5. Its metallic nature and high in-plane anisotropy combine many of the desirable attributes of graphene6 and monolayer black phosphorus7. As a synthetic 2D material, its structural properties cannot be deduced from bulk boron, which implies that the intrinsic defects of borophene remain unexplored. Here we investigate borophene line defects at the atomic scale with ultrahigh vacuum (UHV) scanning tunnelling microscopy/spectroscopy (STM/STS) and density functional theory (DFT). Under suitable growth conditions, borophene phases that correspond to the v1/6 and v1/5 models are found to intermix and accommodate line defects in each other with structures that match the constituent units of the other phase. These line defects energetically favour spatially periodic self-assembly that gives rise to new borophene phases, which ultimately blurs the distinction between borophene crystals and defects. This phenomenon is unique to borophene as a result of its high in-plane anisotropy and energetically and structurally similar polymorphs. Low-temperature measurements further reveal subtle electronic features that are consistent with a charge density wave (CDW), which are modulated by line defects. This atomic-level understanding is likely to inform ongoing efforts to devise and realize applications based on borophene.

    更新日期:2018-07-18
  • Publisher Correction: Carbon nanotubes as emerging quantum-light sources
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-11
    X. He, H. Htoon, S. K. Doorn, W. H. P. Pernice, F. Pyatkov, R. Krupke, A. Jeantet, Y. Chassagneux, C. Voisin

    Publisher Correction: Carbon nanotubes as emerging quantum-light sources Publisher Correction: Carbon nanotubes as emerging quantum-light sources, Published online: 11 July 2018; doi:10.1038/s41563-018-0141-2 Publisher Correction: Carbon nanotubes as emerging quantum-light sources

    更新日期:2018-07-12
  • Impacts of surface depletion on the plasmonic properties of doped semiconductor nanocrystals
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-09
    Omid Zandi, Ankit Agrawal, Alex B. Shearer, Lauren C. Reimnitz, Clayton J. Dahlman, Corey M. Staller, Delia J. Milliron

    Degenerately doped semiconductor nanocrystals (NCs) exhibit a localized surface plasmon resonance (LSPR) in the infrared range of the electromagnetic spectrum. Unlike metals, semiconductor NCs offer tunable LSPR characteristics enabled by doping, or via electrochemical or photochemical charging. Tuning plasmonic properties through carrier density modulation suggests potential applications in smart optoelectronics, catalysis and sensing. Here, we elucidate fundamental aspects of LSPR modulation through dynamic carrier density tuning in Sn-doped In2O3 (Sn:In2O3) NCs. Monodisperse Sn:In2O3 NCs with various doping levels and sizes were synthesized and assembled in uniform films. NC films were then charged in an in situ electrochemical cell and the LSPR modulation spectra were monitored. Based on spectral shifts and intensity modulation of the LSPR, combined with optical modelling, it was found that often-neglected semiconductor properties, specifically band structure modification due to doping and surface states, strongly affect LSPR modulation. Fermi level pinning by surface defect states creates a surface depletion layer that alters the LSPR properties; it determines the extent of LSPR frequency modulation, diminishes the expected near-field enhancement, and strongly reduces sensitivity of the LSPR to the surroundings.

    更新日期:2018-07-10
  • Publisher Correction: Symmetry and magnetism allied
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-09
    Manfred Fiebig

    Publisher Correction: Symmetry and magnetism alliedPublisher Correction: Symmetry and magnetism allied, Published online: 09 July 2018; doi:10.1038/s41563-018-0145-yPublisher Correction: Symmetry and magnetism allied

    更新日期:2018-07-09
  • Coupling two order parameters in a quantum gas
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-02
    Andrea Morales, Philip Zupancic, Julian Léonard, Tilman Esslinger, Tobias Donner

    Controlling matter to simultaneously support coupled properties is of fundamental and technological importance1 (for example, in multiferroics2,3,4,5 or high-temperature superconductors6,7,8,9). However, determining the microscopic mechanisms responsible for the simultaneous presence of different orders is difficult, making it hard to predict material phenomenology10,11 or modify properties12,13,14,15,16. Here, using a quantum gas to engineer an adjustable interaction at the microscopic level, we demonstrate scenarios of competition, coexistence and mutual enhancement of two orders. For the enhancement scenario, the presence of one order lowers the critical point of the other. Our system is realized by a Bose–Einstein condensate that can undergo self-organization phase transitions in two optical resonators17, resulting in two distinct crystalline density orders. We characterize the coupling between these orders by measuring the composite order parameter and the elementary excitations and explain our results with a mean-field free-energy model derived from a microscopic Hamiltonian. Our system is ideally suited to explore quantum tricritical points18 and can be extended to study the interplay of spin and density orders19 as a function of temperature20.

    更新日期:2018-07-02
  • Non-specific interactions govern cytosolic diffusion of nanosized objects in mammalian cells
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-02
    Fred Etoc, Elie Balloul, Chiara Vicario, Davide Normanno, Domenik Liße, Assa Sittner, Jacob Piehler, Maxime Dahan, Mathieu Coppey

    The diffusivity of macromolecules in the cytoplasm of eukaryotic cells varies over orders of magnitude and dictates the kinetics of cellular processes. However, a general description that associates the Brownian or anomalous nature of intracellular diffusion to the architectural and biochemical properties of the cytoplasm has not been achieved. Here we measure the mobility of individual fluorescent nanoparticles in living mammalian cells to obtain a comprehensive analysis of cytoplasmic diffusion. We identify a correlation between tracer size, its biochemical nature and its mobility. Inert particles with size equal or below 50 nm behave as Brownian particles diffusing in a medium of low viscosity with negligible effects of molecular crowding. Increasing the strength of non-specific interactions of the nanoparticles within the cytoplasm gradually reduces their mobility and leads to subdiffusive behaviour. These experimental observations and the transition from Brownian to subdiffusive motion can be captured in a minimal phenomenological model.

    更新日期:2018-07-02
  • Sounds and hydrodynamics of polar active fluids
    Nat. Mater. (IF 39.235) Pub Date : 2018-07-02
    Delphine Geyer, Alexandre Morin, Denis Bartolo

    Spontaneously flowing liquids have been successfully engineered from a variety of biological and synthetic self-propelled units1,2,3,4,5,6,7,8,9,10,11. Together with their orientational order, wave propagation in such active fluids has remained a subject of intense theoretical studies12,13,14,15,16,17. However, the experimental observation of this phenomenon has remained elusive. Here, we establish and exploit the propagation of sound waves in colloidal active materials with broken rotational symmetry. We demonstrate that two mixed modes, coupling density and velocity fluctuations, propagate along all directions in colloidal-roller fluids. We then show how the six material constants defining the linear hydrodynamics of these active liquids can be measured from their spontaneous fluctuation spectrum, while being out of reach of conventional rheological methods. This active-sound spectroscopy is not specific to synthetic active materials and could provide a quantitative hydrodynamic description of herds, flocks and swarms from inspection of their large-scale fluctuations18,19,20,21.

    更新日期:2018-07-02
  • Pure spin currents find the off switch
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25
    Peter Wadley

    Pure spin currents find the off switchPure spin currents find the off switch, Published online: 25 June 2018; doi:10.1038/s41563-018-0125-2A means of reversibly switching spin conductance on or off is demonstrated and brings spintronics using pure spin currents — a prime candidate for the next generation of low-power microelectronic devices — a step closer.

    更新日期:2018-06-27
  • Long-range symmetry breaking in embedded ferroelectrics
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25
    Hugh Simons, Astri Bjørnetun Haugen, Anders Clemen Jakobsen, Søren Schmidt, Frederik Stöhr, Marta Majkut, Carsten Detlefs, John E. Daniels, Dragan Damjanovic, Henning Friis Poulsen

    The characteristic functionality of ferroelectric materials is due to the symmetry of their crystalline structure. As such, ferroelectrics lend themselves to design approaches that manipulate this structural symmetry by introducing extrinsic strain. Using in situ dark-field X-ray microscopy to map lattice distortions around deeply embedded domain walls and grain boundaries in BaTiO3, we reveal that symmetry-breaking strain fields extend up to several micrometres from domain walls. As this exceeds the average domain width, no part of the material is elastically relaxed, and symmetry is universally broken. Such extrinsic strains are pivotal in defining the local properties and self-organization of embedded domain walls, and must be accounted for by emerging computational approaches to material design.

    更新日期:2018-06-27
  • Mechanics-guided developmental fate patterning
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25
    Mukul Tewary, Peter W. Zandstra

    Mechanics-guided developmental fate patterningMechanics-guided developmental fate patterning, Published online: 25 June 2018; doi:10.1038/s41563-018-0121-6A micropatterned human pluripotent stem cell-based developmental model was utilized to demonstrate the role of biophysical cues such as cell size and cytoskeletal contractile forces in directing patterning of neuroepithelial and neural plate border cells.

    更新日期:2018-06-27
  • Seeing the forest and the trees
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25
    Hiroyuki Takenaka, Ilya Grinberg, Andrew M. Rappe

    Seeing the forest and the treesSeeing the forest and the trees, Published online: 25 June 2018; doi:10.1038/s41563-018-0117-2A paradigm relating ultrahigh piezoelectricity and multiscale inhomogeneous structure in relaxor ferroelectrics emerges from state-of-the-art neutron and X-ray diffuse scattering measurements.

    更新日期:2018-06-27
  • Biomaterials driving repair after stroke
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25
    Anup Tuladhar, Molly S. Shoichet

    Biomaterials driving repair after strokeBiomaterials driving repair after stroke, Published online: 25 June 2018; doi:10.1038/s41563-018-0124-3An injectable biomaterial with angiogenic and immune-modulatory properties was developed and shown to support brain tissue repair and functional recovery in a mouse model of stroke.

    更新日期:2018-06-27
  • Hydrogen to the rescue
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25

    Hydrogen to the rescueHydrogen to the rescue, Published online: 25 June 2018; doi:10.1038/s41563-018-0129-yLarge-scale, environmentally friendly hydrogen production will rely on steam methane reforming coupled with carbon capture and electrolysis, but solar fuels could have a disruptive role to play.

    更新日期:2018-06-27
  • The relation of local order to material properties in relaxor ferroelectrics
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25
    M. J. Krogstad, P. M. Gehring, S. Rosenkranz, R. Osborn, F. Ye, Y. Liu, J. P. C. Ruff, W. Chen, J. M. Wozniak, H. Luo, O. Chmaissem, Z.-G. Ye, D. Phelan

    Correlating electromechanical and dielectric properties with nanometre-scale order is the defining challenge for the development of piezoelectric oxides. Current lead (Pb)-based relaxor ferroelectrics can serve as model systems with which to unravel these correlations, but the nature of the local order and its relation to material properties remains controversial. Here we employ recent advances in diffuse scattering instrumentation to investigate crystals that span the phase diagram of PbMg1/3Nb2/3O3-xPbTiO3 (PMN-xPT) and identify four forms of local order. From the compositional dependence, we resolve the coupling of each form to the dielectric and electromechanical properties observed. We show that relaxor behaviour does not correlate simply with ferroic diffuse scattering; instead, it results from a competition between local antiferroelectric correlations, seeded by chemical short-range order, and local ferroic order. The ferroic diffuse scattering is strongest where piezoelectricity is maximal and displays previously unrecognized modulations caused by anion displacements. Our observations provide new guidelines for evaluating displacive models and hence the piezoelectric properties of environmentally friendly next-generation materials.

    更新日期:2018-06-27
  • Out of step with time
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-25
    Philip Ball

    Out of step with timeOut of step with time, Published online: 25 June 2018; doi:10.1038/s41563-018-0127-0Out of step with time

    更新日期:2018-06-27
  • Monatomic phase change memory
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-18
    Martin Salinga, Benedikt Kersting, Ider Ronneberger, Vara Prasad Jonnalagadda, Xuan Thang Vu, Manuel Le Gallo, Iason Giannopoulos, Oana Cojocaru-Mirédin, Riccardo Mazzarello, Abu Sebastian

    Phase change memory has been developed into a mature technology capable of storing information in a fast and non-volatile way1,2,3, with potential for neuromorphic computing applications4,5,6. However, its future impact in electronics depends crucially on how the materials at the core of this technology adapt to the requirements arising from continued scaling towards higher device densities. A common strategy to fine-tune the properties of phase change memory materials, reaching reasonable thermal stability in optical data storage, relies on mixing precise amounts of different dopants, resulting often in quaternary or even more complicated compounds6,7,8. Here we show how the simplest material imaginable, a single element (in this case, antimony), can become a valid alternative when confined in extremely small volumes. This compositional simplification eliminates problems related to unwanted deviations from the optimized stoichiometry in the switching volume, which become increasingly pressing when devices are aggressively miniaturized9,10. Removing compositional optimization issues may allow one to capitalize on nanosize effects in information storage.

    更新日期:2018-06-18
  • Symmetry and magnetism allied
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-18
    Manfred Fiebig

    Symmetry and magnetism allied Symmetry and magnetism allied, Published online: 18 June 2018; doi:10.1038/s41563-018-0113-6 By transferring the symmetry conditions of electric polarization patterns to the field of magnetism, a particularly stable magnetic configuration is obtained that could be interesting for voltage-controlled magnetic devices.

    更新日期:2018-06-18
  • Carbon nanotubes as emerging quantum-light sources
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-18
    X. He, H. Htoon, S. K. Doorn, W. H. P. Pernice, F. Pyatkov, R. Krupke, A. Jeantet, Y. Chassagneux, C. Voisin

    Progress in quantum computing and quantum cryptography requires efficient, electrically triggered, single-photon sources at room temperature in the telecom wavelengths. It has been long known that semiconducting single-wall carbon nanotubes (SWCNTs) display strong excitonic binding and emit light over a broad range of wavelengths, but their use has been hampered by a low quantum yield and a high sensitivity to spectral diffusion and blinking. In this Perspective, we discuss recent advances in the mastering of SWCNT optical properties by chemistry, electrical contacting and resonator coupling towards advancing their use as quantum light sources. We describe the latest results in terms of single-photon purity, generation efficiency and indistinguishability. Finally, we consider the main fundamental challenges stemming from the unique properties of SWCNTs and the most promising roads for SWCNT-based chip integrated quantum photonic sources.

    更新日期:2018-06-18
  • Single-element glass to record data
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-18
    Wei Zhang, Evan Ma

    Single-element glass to record data Single-element glass to record data, Published online: 18 June 2018; doi:10.1038/s41563-018-0114-5 Monatomic glassy antimony can now be achieved via melt-quenching in a nanoconfined volume in a device setting. In contrast to alloys currently used in phase-change memories, deviation from optimized composition is no longer an issue in this simple material.

    更新日期:2018-06-18
  • Observation of magnetic vortex pairs at room temperature in a planar α-Fe2O3/Co heterostructure
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-18
    F. P. Chmiel, N. Waterfield Price, R. D. Johnson, A. D. Lamirand, J. Schad, G. van der Laan, D. T. Harris, J. Irwin, M. S. Rzchowski, C.-B. Eom, P. G. Radaelli

    Vortices, occurring whenever a flow field ‘whirls’ around a one-dimensional core, are among the simplest topological structures, ubiquitous to many branches of physics. In the crystalline state, vortex formation is rare, since it is generally hampered by long-range interactions: in ferroic materials (ferromagnetic and ferroelectric), vortices are observed only when the effects of the dipole–dipole interaction are modified by confinement at the nanoscale1,2,3, or when the parameter associated with the vorticity does not couple directly with strain4. Here, we observe an unprecedented form of vortices in antiferromagnetic haematite (α-Fe2O3) epitaxial films, in which the primary whirling parameter is the staggered magnetization. Remarkably, ferromagnetic topological objects with the same vorticity and winding number as the α-Fe2O3 vortices are imprinted onto an ultra-thin Co ferromagnetic over-layer by interfacial exchange. Our data suggest that the ferromagnetic vortices may be merons (half-skyrmions, carrying an out-of plane core magnetization), and indicate that the vortex/meron pairs can be manipulated by the application of an in-plane magnetic field, giving rise to large-scale vortex–antivortex annihilation.

    更新日期:2018-06-18
  • Perovskites cover silicon textures
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    Anita Ho-Baillie

    Perovskites cover silicon textures Perovskites cover silicon textures, Published online: 11 June 2018; doi:10.1038/s41563-018-0122-5 A two-step deposition method has been developed that enables the conformal coating of textured surfaces with perovskite films. This allows the realization of perovskite/silicon tandem solar cells with increased short-circuit current density.

    更新日期:2018-06-12
  • Therapeutic luminal coating of the intestine
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    Yuhan Lee, Tara E. Deelman, Keyue Chen, Dawn S. Y. Lin, Ali Tavakkoli, Jeffrey M. Karp

    The gastrointestinal tract is the site of most drug delivery and therapeutic interventions for the management and treatment of numerous diseases. However, selective access to its mucosa, especially in the small bowel, is challenging. Here we develop an orally administered gut-coating formulation that provides a transient coating of the bowel. Through a materials screening campaign, we identified a sucrose octasulfate aluminium complex and further engineered the pH-dependent material into a complex coacervate formulation linked via pH-independent electrostatic interaction, which allowed an effective transient physical coating on the gastrointestinal mucosa, independent of gastric acid exposure. We tested the therapeutic values of this technology in two settings. Oral administration of this gut-coating formulation modulated the nutrient contact with bowel mucosa, which lowered the glucose responses in rodent models indicating a potential therapeutic utility in diabetes. Furthermore, the formulation protected biological agents from gastric acid exposure and degradation, which enabled oral delivery to the small bowel mucosa.

    更新日期:2018-06-12
  • Reversible adsorption of nitrogen dioxide within a robust porous metal–organic framework
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    Xue Han, Harry G. W. Godfrey, Lydia Briggs, Andrew J. Davies, Yongqiang Cheng, Luke L. Daemen, Alena M. Sheveleva, Floriana Tuna, Eric J. L. McInnes, Junliang Sun, Christina Drathen, Michael W. George, Anibal J. Ramirez-Cuesta, K. Mark Thomas, Sihai Yang, Martin Schröder

    Nitrogen dioxide (NO2) is a major air pollutant causing significant environmental1,2 and health problems3,4. We report reversible adsorption of NO2 in a robust metal–organic framework. Under ambient conditions, MFM-300(Al) exhibits a reversible NO2 isotherm uptake of 14.1 mmol g−1, and, more importantly, exceptional selective removal of low-concentration NO2 (5,000 to <1 ppm) from gas mixtures. Complementary experiments reveal five types of supramolecular interaction that cooperatively bind both NO2 and N2O4 molecules within MFM-300(Al). We find that the in situ equilibrium 2NO2 ↔ N2O4 within the pores is pressure-independent, whereas ex situ this equilibrium is an exemplary pressure-dependent first-order process. The coexistence of helical monomer–dimer chains of NO2 in MFM-300(Al) could provide a foundation for the fundamental understanding of the chemical properties of guest molecules within porous hosts. This work may pave the way for the development of future capture and conversion technologies.

    更新日期:2018-06-12
  • Still plenty to explore
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    Brian Gleeson

    Still plenty to explore Still plenty to explore, Published online: 11 June 2018; doi:10.1038/s41563-018-0119-0 Advanced characterization and modelling techniques provide unique insights into oxidant transport processes in growing scales of high-temperature alloys and alloy design for improving their degradation resistance in harsh environments.

    更新日期:2018-06-12
  • Homochiral porous nanosheets for enantiomer sieving
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    Bo Sun, Yongju Kim, Yanqiu Wang, Huaxin Wang, Jehan Kim, Xin Liu, Myongsoo Lee

    Protein pores are highly specific in binding to chiral substrates and in catalysing stereospecific reactions, because their active pockets are asymmetric and stereoselective1,2. Chiral binding materials from molecular-level pores with high specificity have not been achieved because of problems with pore deformation and blocking3. A promising solution is the self-assembly of single sheets where all pores are exposed to the environment, for example as metal–organic frameworks4, polymers5,6 or non-covalent aromatic networks7,8,9,10, but, typically, the pores are distant from the internal cavities with chirality. Here, we report the synthesis of homochiral porous nanosheets achieved by the 2D self-assembly of non-chiral macrocycles, with open/closed pore switching. Pore chirality is spontaneously induced by a twisted stack of dimeric macrocycles. The porous 2D structures can serve as enantiomer sieving membranes that exclusively capture a single enantiomer in a racemic mixture solution, with uptake capacity greater than 96%. Moreover, the entrapped guests inside the pores can be pumped out by pore closing triggered by external stimuli. This strategy could provide new opportunities for controlled molecule release, as well as for artificial cells.

    更新日期:2018-06-12
  • Interplay of water and reactive elements in oxidation of alumina-forming alloys
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    N. Mortazavi, C. Geers, M. Esmaily, V. Babic, M. Sattari, K. Lindgren, P. Malmberg, B. Jönsson, M. Halvarsson, J. E. Svensson, I. Panas, L. G. Johansson

    High-temperature alloys are crucial to many important technologies that underpin our civilization. All these materials rely on forming an external oxide layer (scale) for corrosion protection. Despite decades of research on oxide scale growth, many open questions remain, including the crucial role of the so-called reactive elements and water. Here, we reveal the hitherto unknown interplay between reactive elements and water during alumina scale growth, causing a metastable ‘messy’ nano-structured alumina layer to form. We propose that reactive-element-decorated, hydroxylated interfaces between alumina nanograins enable water to access an inner cathode in the bottom of the scale, at odds with the established scale growth scenario. As evidence, hydride-nanodomains and reactive element/hydrogen (deuterium) co-variation are observed in the alumina scale. The defect-rich alumina subsequently recrystallizes to form a protective scale. First-principles modelling is also performed to validate the RE effect. Our findings open up promising avenues in oxidation research and suggest ways to improve alloy properties.

    更新日期:2018-06-12
  • Re-entrant charge order in overdoped (Bi,Pb)2.12Sr1.88CuO6+δ outside the pseudogap regime
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    Y. Y. Peng, R. Fumagalli, Y. Ding, M. Minola, S. Caprara, D. Betto, M. Bluschke, G. M. De Luca, K. Kummer, E. Lefrançois, M. Salluzzo, H. Suzuki, M. Le Tacon, X. J. Zhou, N. B. Brookes, B. Keimer, L. Braicovich, M. Grilli, G. Ghiringhelli

    In the underdoped regime, the cuprate high-temperature superconductors exhibit a host of unusual collective phenomena, including unconventional spin and charge density modulations, Fermi surface reconstructions, and a pseudogap in various physical observables. Conversely, overdoped cuprates are generally regarded as conventional Fermi liquids possessing no collective electronic order. In partial contradiction to this widely held picture, we report resonant X-ray scattering measurements revealing incommensurate charge order reflections for overdoped (Bi,Pb)2.12Sr1.88CuO6+δ (Bi2201), with correlation lengths of 40–60 lattice units, that persist up to temperatures of at least 250 K. The value of the charge order wavevector decreases with doping, in line with the extrapolation of the trend previously observed in underdoped Bi2201. In overdoped materials, however, charge order coexists with a single, unreconstructed Fermi surface without nesting or pseudogap features. The discovery of re-entrant charge order in Bi2201 thus calls for investigations in other cuprate families and for a reconsideration of theories that posit an essential relationship between these phenomena.

    更新日期:2018-06-12
  • Fully textured monolithic perovskite/silicon tandem solar cells with 25.2% power conversion efficiency
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-11
    Florent Sahli, Jérémie Werner, Brett A. Kamino, Matthias Bräuninger, Raphaël Monnard, Bertrand Paviet-Salomon, Loris Barraud, Laura Ding, Juan J. Diaz Leon, Davide Sacchetto, Gianluca Cattaneo, Matthieu Despeisse, Mathieu Boccard, Sylvain Nicolay, Quentin Jeangros, Bjoern Niesen, Christophe Ballif

    Tandem devices combining perovskite and silicon solar cells are promising candidates to achieve power conversion efficiencies above 30% at reasonable costs. State-of-the-art monolithic two-terminal perovskite/silicon tandem devices have so far featured silicon bottom cells that are polished on their front side to be compatible with the perovskite fabrication process. This concession leads to higher potential production costs, higher reflection losses and non-ideal light trapping. To tackle this issue, we developed a top cell deposition process that achieves the conformal growth of multiple compounds with controlled optoelectronic properties directly on the micrometre-sized pyramids of textured monocrystalline silicon. Tandem devices featuring a silicon heterojunction cell and a nanocrystalline silicon recombination junction demonstrate a certified steady-state efficiency of 25.2%. Our optical design yields a current density of 19.5 mA cm−2 thanks to the silicon pyramidal texture and suggests a path for the realization of 30% monolithic perovskite/silicon tandem devices.

    更新日期:2018-06-12
  • Reducing localization
    Nat. Mater. (IF 39.235) Pub Date : 
    A. Alec Talin, François Léonard

    Reducing localization Reducing localization, Published online: 04 June 2018; doi:10.1038/s41563-018-0103-8 By inserting potassium into a 3D metal–organic framework band delocalization occurs, enabling mobilities and conductivities similar to organic polymers.

    更新日期:2018-06-05
  • Electron delocalization and charge mobility as a function of reduction in a metal–organic framework
    Nat. Mater. (IF 39.235) Pub Date : 
    Michael L. Aubrey, Brian M. Wiers, Sean C. Andrews, Tsuneaki Sakurai, Sebastian E. Reyes-Lillo, Samia M. Hamed, Chung-Jui Yu, Lucy E. Darago, Jarad A. Mason, Jin-Ook Baeg, Fernande Grandjean, Gary J. Long, Shu Seki, Jeffrey B. Neaton, Peidong Yang, Jeffrey R. Long

    Electron delocalization and charge mobility as a function of reduction in a metal–organic framework Electron delocalization and charge mobility as a function of reduction in a metal–organic framework, Published online: 04 June 2018; doi:10.1038/s41563-018-0098-1 A conducting metal–organic framework with charge delocalization by reductive potassium insertion is demonstrated. Integration into a field-effect transistor shows similar mobilities to semiconductors, with a mobility estimated to be at least 0.84 cm2 V–1 s–1.

    更新日期:2018-06-05
  • Terahertz-light quantum tuning of a metastable emergent phase hidden by superconductivity
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-04
    X. Yang, C. Vaswani, C. Sundahl, M. Mootz, P. Gagel, L. Luo, J. H. Kang, P. P. Orth, I. E. Perakis, C. B. Eom, J. Wang

    ‘Sudden’ quantum quench and prethermalization have become a cross-cutting theme for discovering emergent states of matter1,2,3,4. Yet this remains challenging in electron matter5,6,7,8,9, especially superconductors10,11,12,13,14. The grand question of what is hidden underneath superconductivity (SC)15 appears universal, but poorly understood. Here we reveal a long-lived gapless quantum phase of prethermalized quasiparticles (QPs) after a single-cycle terahertz (THz) quench of a Nb3Sn SC gap. Its conductivity spectra is characterized by a sharp coherent peak and a vanishing scattering rate that decreases almost linearly towards zero frequency, which is most pronounced around the full depletion of the condensate and absent for a high-frequency pump. Above a critical pump threshold, such a QP phase with coherent transport and memory persists as an unusual prethermalization plateau, without relaxation to normal and SC thermal states for an order of magnitude longer than the QP recombination and thermalization times. Switching to this metastable ‘quantum QP fluid’ signals non-thermal quench of coupled SC and charge-density-wave (CDW)-like orders and hints quantum control beneath the SC.

    更新日期:2018-06-05
  • Local immunomodulation with Fas ligand-engineered biomaterials achieves allogeneic islet graft acceptance
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-04
    Devon M. Headen, Kyle B. Woodward, María M. Coronel, Pradeep Shrestha, Jessica D. Weaver, Hong Zhao, Min Tan, Michael D. Hunckler, William S. Bowen, Christopher T. Johnson, Lonnie Shea, Esma S. Yolcu, Andrés J. García, Haval Shirwan

    Islet transplantation is a promising therapy for type 1 diabetes. However, chronic immunosuppression to control rejection of allogeneic islets induces morbidities and impairs islet function. T effector cells are responsible for islet allograft rejection and express Fas death receptors following activation, becoming sensitive to Fas-mediated apoptosis. Here, we report that localized immunomodulation using microgels presenting an apoptotic form of the Fas ligand with streptavidin (SA-FasL) results in prolonged survival of allogeneic islet grafts in diabetic mice. A short course of rapamycin treatment boosted the immunomodulatory efficacy of SA-FasL microgels, resulting in acceptance and function of allografts over 200 days. Survivors generated normal systemic responses to donor antigens, implying immune privilege of the graft, and had increased CD4+CD25+FoxP3+ T regulatory cells in the graft and draining lymph nodes. Deletion of T regulatory cells resulted in acute rejection of established islet allografts. This localized immunomodulatory biomaterial-enabled approach may provide an alternative to chronic immunosuppression for clinical islet transplantation.

    更新日期:2018-06-05
  • Electrifying model catalysts for understanding electrocatalytic reactions in liquid electrolytes
    Nat. Mater. (IF 39.235) Pub Date : 2018-06-04
    Firas Faisal, Corinna Stumm, Manon Bertram, Fabian Waidhas, Yaroslava Lykhach, Serhiy Cherevko, Feifei Xiang, Maximilian Ammon, Mykhailo Vorokhta, Břetislav Šmíd, Tomáš Skála, Nataliya Tsud, Armin Neitzel, Klára Beranová, Kevin C. Prince, Simon Geiger, Olga Kasian, Tobias Wähler, Ralf Schuster, M. Alexander Schneider, Vladimír Matolín, Karl J. J. Mayrhofer, Olaf Brummel, Jörg Libuda

    Electrocatalysis is at the heart of our future transition to a renewable energy system. Most energy storage and conversion technologies for renewables rely on electrocatalytic processes and, with increasing availability of cheap electrical energy from renewables, chemical production will witness electrification in the near future1,2,3. However, our fundamental understanding of electrocatalysis lags behind the field of classical heterogeneous catalysis that has been the dominating chemical technology for a long time. Here, we describe a new strategy to advance fundamental studies on electrocatalytic materials. We propose to ‘electrify’ complex oxide-based model catalysts made by surface science methods to explore electrocatalytic reactions in liquid electrolytes. We demonstrate the feasibility of this concept by transferring an atomically defined platinum/cobalt oxide model catalyst into the electrochemical environment while preserving its atomic surface structure. Using this approach, we explore particle size effects and identify hitherto unknown metal–support interactions that stabilize oxidized platinum at the nanoparticle interface. The metal–support interactions open a new synergistic reaction pathway that involves both metallic and oxidized platinum. Our results illustrate the potential of the concept, which makes available a systematic approach to build atomically defined model electrodes for fundamental electrocatalytic studies.

    更新日期:2018-06-05
  • Author Correction: Room-temperature ductile inorganic semiconductor
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-30
    Xun Shi, Hongyi Chen, Feng Hao, Ruiheng Liu, Tuo Wang, Pengfei Qiu, Ulrich Burkhardt, Yuri Grin, Lidong Chen

    Author Correction: Room-temperature ductile inorganic semiconductor Author Correction: Room-temperature ductile inorganic semiconductor, Published online: 30 May 2018; doi:10.1038/s41563-018-0111-8 Author Correction: Room-temperature ductile inorganic semiconductor

    更新日期:2018-05-31
  • Significant Dzyaloshinskii–Moriya interaction at graphene–ferromagnet interfaces due to the Rashba effect
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-28
    Hongxin Yang, Gong Chen, Alexandre A. C. Cotta, Alpha T. N’Diaye, Sergey A. Nikolaev, Edmar A. Soares, Waldemar A. A. Macedo, Kai Liu, Andreas K. Schmid, Albert Fert, Mairbek Chshiev

    The possibility of utilizing the rich spin-dependent properties of graphene has attracted much attention in the pursuit of spintronics advances. The promise of high-speed and low-energy-consumption devices motivates the search for layered structures that stabilize chiral spin textures such as topologically protected skyrmions. Here we demonstrate that chiral spin textures are induced at graphene/ferromagnetic metal interfaces. Graphene is a weak spin–orbit coupling material and is generally not expected to induce a sufficient Dzyaloshinskii–Moriya interaction to affect magnetic chirality. We demonstrate that indeed graphene does induce a type of Dzyaloshinskii–Moriya interaction due to the Rashba effect. First-principles calculations and experiments using spin-polarized electron microscopy show that this graphene-induced Dzyaloshinskii–Moriya interaction can have a similar magnitude to that at interfaces with heavy metals. This work paves a path towards two-dimensional-material-based spin–orbitronics.

    更新日期:2018-05-29
  • Spin colossal magnetoresistance in an antiferromagnetic insulator
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-28
    Zhiyong Qiu, Dazhi Hou, Joseph Barker, Kei Yamamoto, Olena Gomonay, Eiji Saitoh

    Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal–insulator transition and has inspired extensive studies for decades1,2. Here we demonstrate an analogous spin effect near the Néel temperature, TN = 296 K, of the antiferromagnetic insulator Cr2O3. Using a yttrium iron garnet YIG/Cr2O3/Pt trilayer, we injected a spin current from the YIG into the Cr2O3 layer and collected, via the inverse spin Hall effect, the spin signal transmitted into the heavy metal Pt. We observed a two orders of magnitude difference in the transmitted spin current within 14 K of the Néel temperature. This transition between spin conducting and non-conducting states was also modulated by a magnetic field in isothermal conditions. This effect, which we term spin colossal magnetoresistance (SCMR), has the potential to simplify the design of fundamental spintronics components, for instance, by enabling the realization of spin-current switches or spin-current-based memories.

    更新日期:2018-05-29
  • Self-assembled highly ordered acid layers in precisely sulfonated polyethylene produce efficient proton transport
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-28
    Edward B. Trigg, Taylor W. Gaines, Manuel Maréchal, Demi E. Moed, Patrice Rannou, Kenneth B. Wagener, Mark J. Stevens, Karen I. Winey

    Recent advances in polymer synthesis have allowed remarkable control over chain microstructure and conformation. Capitalizing on such developments, here we create well-controlled chain folding in sulfonated polyethylene, leading to highly uniform hydrated acid layers of subnanometre thickness with high proton conductivity. The linear polyethylene contains sulfonic acid groups pendant to precisely every twenty-first carbon atom that induce tight chain folds to form the hydrated layers, while the methylene segments crystallize. The proton conductivity is on par with Nafion 117, the benchmark for fuel cell membranes. We demonstrate that well-controlled hairpin chain folding can be utilized for proton conductivity within a crystalline polymer structure, and we project that this structure could be adapted for ion transport. This layered polyethylene-based structure is an innovative and versatile design paradigm for functional polymer membranes, opening doors to efficient and selective transport of other ions and small molecules on appropriate selection of functional groups.

    更新日期:2018-05-29
  • Holstein polaron in a valley-degenerate two-dimensional semiconductor
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-28
    Mingu Kang, Sung Won Jung, Woo Jong Shin, Yeongsup Sohn, Sae Hee Ryu, Timur K. Kim, Moritz Hoesch, Keun Su Kim

    Two-dimensional (2D) crystals have emerged as a class of materials with tunable carrier density1. Carrier doping to 2D semiconductors can be used to modulate many-body interactions2 and to explore novel composite particles. The Holstein polaron is a small composite particle of an electron that carries a cloud of self-induced lattice deformation (or phonons)3,4,5, which has been proposed to play a key role in high-temperature superconductivity6 and carrier mobility in devices7. Here we report the discovery of Holstein polarons in a surface-doped layered semiconductor, MoS2, in which a puzzling 2D superconducting dome with the critical temperature of 12 K was found recently8,9,10,11. Using a high-resolution band mapping of charge carriers, we found strong band renormalizations collectively identified as a hitherto unobserved spectral function of Holstein polarons12,13,14,15,16,17,18. The short-range nature of electron–phonon (e–ph) coupling in MoS2 can be explained by its valley degeneracy, which enables strong intervalley coupling mediated by acoustic phonons. The coupling strength is found to increase gradually along the superconducting dome up to the intermediate regime, which suggests a bipolaronic pairing in the 2D superconductivity.

    更新日期:2018-05-29
  • Rejuvenating zinc batteries
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23
    Enyuan Hu, Xiao-Qing Yang

    Rejuvenating zinc batteries Rejuvenating zinc batteries, Published online: 23 May 2018; doi:10.1038/s41563-018-0090-9 By using high-concentration salt in electrolyte, water is replaced in the zinc solvation-sheath and a zinc anode is developed with high reversibility and stability

    更新日期:2018-05-24
  • Tailor-made currents
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23
    Frank Freimuth

    Tailor-made currents Tailor-made currents, Published online: 23 May 2018; doi:10.1038/s41563-018-0086-5 Spin currents in magnetic trilayers exhibit an unexpected spin polarization that facilitates current-induced switching of magnetization.

    更新日期:2018-05-24
  • Dendritic cells in cancer immunotherapy
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23
    Camille M. Le Gall, Jorieke Weiden, Loek J. Eggermont, Carl G. Figdor

    Dendritic cells in cancer immunotherapy Dendritic cells in cancer immunotherapy, Published online: 23 May 2018; doi:10.1038/s41563-018-0093-6 Camille M. Le Gall, Jorieke Weiden, Loek J. Eggermont and Carl G. Figdor provide an overview of immunotherapeutics for cancer treatment that harness dendritic cells, their challenges in clinical use, and approaches employed to enhance their recruitment and activation to promote effective anti-tumour immunity.

    更新日期:2018-05-24
  • Material aid for vaccines
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23
    Darrell Irvine

    Material aid for vaccines Material aid for vaccines, Published online: 23 May 2018; doi:10.1038/s41563-018-0089-2 Darrell Irvine provides an overview of the recent advances in materials science that have enabled the use of innovative natural and synthetic compounds in vaccine development capable of regulating the potency and safety of new vaccines progressing towards the clinic.

    更新日期:2018-05-24
  • The big squeeze
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23
    Maria Maragkou

    The big squeeze The big squeeze, Published online: 23 May 2018; doi:10.1038/s41563-018-0100-y The big squeeze

    更新日期:2018-05-24
  • Cancer immunotherapy making headway
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23
    Amos Matsiko

    Cancer immunotherapy making headway Cancer immunotherapy making headway, Published online: 23 May 2018; doi:10.1038/s41563-018-0091-8 Cancer immunotherapy making headway

    更新日期:2018-05-24
  • Adoptive T cell cancer therapy
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23
    Karine N. Dzhandzhugazyan, Per Guldberg, Alexei F. Kirkin

    Adoptive T cell cancer therapy Adoptive T cell cancer therapy, Published online: 23 May 2018; doi:10.1038/s41563-018-0094-5 Tumour heterogeneity and off-target toxicity are current challenges of cancer immunotherapy. Karine Dzhandzhugazyan, Per Guldberg and Alexei Kirkin discuss how epigenetic induction of tumour antigens in antigen-presenting cells may form the basis for multi-target therapies.

    更新日期:2018-05-24
  • Cells and materials in immunotherapy
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-23

    Cells and materials in immunotherapy Cells and materials in immunotherapy, Published online: 23 May 2018; doi:10.1038/s41563-018-0102-9 As the interaction of the immune system with the tumour microenvironment becomes increasingly understood, more evidence indicates how immunotherapy can be employed to better eliminate cancers.

    更新日期:2018-05-24
  • Dual-function injectable angiogenic biomaterial for the repair of brain tissue following stroke
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-21
    Lina R. Nih, Shiva Gojgini, S. Thomas Carmichael, Tatiana Segura

    Stroke is the primary cause of disability due to the brain's limited ability to regenerate damaged tissue. After stroke, an increased inflammatory and immune response coupled with severely limited angiogenesis and neuronal growth results in a stroke cavity devoid of normal brain tissue. In the adult, therapeutic angiogenic materials have been used to repair ischaemic tissues through the formation of vascular networks. However, whether a therapeutic angiogenic material can regenerate brain tissue and promote neural repair is poorly understood. Here we show that the delivery of an engineered immune-modulating angiogenic biomaterial directly to the stroke cavity promotes tissue formation de novo, and results in axonal networks along thee generated blood vessels. This regenerated tissue produces functional recovery through the established axonal networks. Thus, this biomaterials approach generates a vascularized network of regenerated functional neuronal connections within previously dead tissue and lays the groundwork for the use of angiogenic materials to repair other neurologically diseased tissues.

    更新日期:2018-05-22
  • Designing natural and synthetic immune tissues
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-21
    Emily A. Gosselin, Haleigh B. Eppler, Jonathan S. Bromberg, Christopher M. Jewell

    Vaccines and immunotherapies have provided enormous improvements for public health, but there are fundamental disconnects between where most studies are performed—in cell culture and animal models—and the ultimate application in humans. Engineering immune tissues and organs, such as bone marrow, thymus, lymph nodes and spleen, could be instrumental in overcoming these hurdles. Fundamentally, designed immune tissues could serve as in vitro tools to more accurately study human immune function and disease, while immune tissues engineered for implantation as next-generation vaccines or immunotherapies could enable direct, on-demand control over generation and regulation of immune function. In this Review, we discuss recent interdisciplinary strategies that are merging materials science and immunology to create engineered immune tissues in vitro and in vivo. We also highlight the hurdles facing these approaches and the need for comparison to existing clinical options, relevant animal models, and other emerging technologies.

    更新日期:2018-05-22
  • An autonomously electrically self-healing liquid metal–elastomer composite for robust soft-matter robotics and electronics
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-21
    Eric J. Markvicka, Michael D. Bartlett, Xiaonan Huang, Carmel Majidi

    Large-area stretchable electronics are critical for progress in wearable computing, soft robotics and inflatable structures. Recent efforts have focused on engineering electronics from soft materials—elastomers, polyelectrolyte gels and liquid metal. While these materials enable elastic compliance and deformability, they are vulnerable to tearing, puncture and other mechanical damage modes that cause electrical failure. Here, we introduce a material architecture for soft and highly deformable circuit interconnects that are electromechanically stable under typical loading conditions, while exhibiting uncompromising resilience to mechanical damage. The material is composed of liquid metal droplets suspended in a soft elastomer; when damaged, the droplets rupture to form new connections with neighbours and re-route electrical signals without interruption. Since self-healing occurs spontaneously, these materials do not require manual repair or external heat. We demonstrate this unprecedented electronic robustness in a self-repairing digital counter and self-healing soft robotic quadruped that continue to function after significant damage.

    更新日期:2018-05-22
  • Mechanics-guided embryonic patterning of neuroectoderm tissue from human pluripotent stem cells
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-21
    Xufeng Xue, Yubing Sun, Agnes M. Resto-Irizarry, Ye Yuan, Koh Meng Aw Yong, Yi Zheng, Shinuo Weng, Yue Shao, Yimin Chai, Lorenz Studer, Jianping Fu

    Classic embryological studies have successfully applied genetics and cell biology principles to understand embryonic development. However, it remains unresolved how mechanics, as an integral driver of development, is involved in controlling tissue-scale cell fate patterning. Here we report a micropatterned human pluripotent stem (hPS)-cell-based neuroectoderm developmental model, in which pre-patterned geometrical confinement induces emergent patterning of neuroepithelial and neural plate border cells, mimicking neuroectoderm regionalization during early neurulation in vivo. In this hPS-cell-based neuroectoderm patterning model, two tissue-scale morphogenetic signals—cell shape and cytoskeletal contractile force—instruct neuroepithelial/neural plate border patterning via BMP-SMAD signalling. We further show that ectopic mechanical activation and exogenous BMP signalling modulation are sufficient to perturb neuroepithelial/neural plate border patterning. This study provides a useful microengineered, hPS-cell-based model with which to understand the biomechanical principles that guide neuroectoderm patterning and hence to study neural development and disease.

    更新日期:2018-05-22
  • The role of metal/oxide interfaces for long-range metal particle activation during CO oxidation
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-14
    Yuri Suchorski, Sergey M. Kozlov, Ivan Bespalov, Martin Datler, Diana Vogel, Zuzana Budinska, Konstantin M. Neyman, Günther Rupprechter

    The role of metal/oxide interfaces for long-range metal particle activation during CO oxidation The role of metal/oxide interfaces for long-range metal particle activation during CO oxidation, Published online: 14 May 2018; doi:10.1038/s41563-018-0080-y Electron microscopy and modelling are used to study CO oxidation on oxide-supported Pd. The perimeter of the metal/oxide interface is shown to affect CO tolerance of the entire particle, demonstrating a long-range effect over micrometre length scales.

    更新日期:2018-05-15
  • Electron–phonon interaction in efficient perovskite blue emitters
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-14
    Xiwen Gong, Oleksandr Voznyy, Ankit Jain, Wenjia Liu, Randy Sabatini, Zachary Piontkowski, Grant Walters, Golam Bappi, Sergiy Nokhrin, Oleksandr Bushuyev, Mingjian Yuan, Riccardo Comin, David McCamant, Shana O. Kelley, Edward H. Sargent

    Low-dimensional perovskites have—in view of their high radiative recombination rates—shown great promise in achieving high luminescence brightness and colour saturation. Here we investigate the effect of electron–phonon interactions on the luminescence of single crystals of two-dimensional perovskites, showing that reducing these interactions can lead to bright blue emission in two-dimensional perovskites. Resonance Raman spectra and deformation potential analysis show that strong electron–phonon interactions result in fast non-radiative decay, and that this lowers the photoluminescence quantum yield (PLQY). Neutron scattering, solid-state NMR measurements of spin–lattice relaxation, density functional theory simulations and experimental atomic displacement measurements reveal that molecular motion is slowest, and rigidity greatest, in the brightest emitter. By varying the molecular configuration of the ligands, we show that a PLQY up to 79% and linewidth of 20 nm can be reached by controlling crystal rigidity and electron–phonon interactions. Designing crystal structures with electron–phonon interactions in mind offers a previously underexplored avenue to improve optoelectronic materials' performance.

    更新日期:2018-05-15
  • Materials challenges for the Starshot lightsail
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-07
    Harry A. Atwater, Artur R. Davoyan, Ognjen Ilic, Deep Jariwala, Michelle C. Sherrott, Cora M. Went, William S. Whitney, Joeson Wong

    Materials challenges for the Starshot lightsail Materials challenges for the Starshot lightsail, Published online: 07 May 2018; doi:10.1038/s41563-018-0075-8 This Perspective explores the optical, mechanical and thermal properties required to successfully design an ultralight spacecraft that can reach Proxima Centauri b, which is the goal of the Starshot Breakthrough Initiative.

    更新日期:2018-05-08
  • Atomic origins of water-vapour-promoted alloy oxidation
    Nat. Mater. (IF 39.235) Pub Date : 2018-05-07
    Langli Luo, Mao Su, Pengfei Yan, Lianfeng Zou, Daniel K. Schreiber, Donald R. Baer, Zihua Zhu, Guangwen Zhou, Yanting Wang, Stephen M. Bruemmer, Zhijie Xu, Chongmin Wang

    The presence of water vapour, intentional or unavoidable, is crucial to many materials applications, such as in steam generators, turbine engines, fuel cells, catalysts and corrosion1,2,3,4. Phenomenologically, water vapour has been noted to accelerate oxidation of metals and alloys5,6. However, the atomistic mechanisms behind such oxidation remain elusive. Through direct in situ atomic-scale transmission electron microscopy observations and density functional theory calculations, we reveal that water-vapour-enhanced oxidation of a nickel–chromium alloy is associated with proton-dissolution-promoted formation, migration, and clustering of both cation and anion vacancies. Protons derived from water dissociation can occupy interstitial positions in the oxide lattice, consequently lowering vacancy formation energy and decreasing the diffusion barrier of both cations and anions, which leads to enhanced oxidation in moist environments at elevated temperatures. This work provides insights into water-vapour-enhanced alloy oxidation and has significant implications in other material and chemical processes involving water vapour, such as corrosion, heterogeneous catalysis and ionic conduction.

    更新日期:2018-05-08
  • An unusual continuous paramagnetic-limited superconducting phase transition in 2D NbSe 2
    Nat. Mater. (IF 39.235) Pub Date : 2018-04-30
    Egon Sohn, Xiaoxiang Xi, Wen-Yu He, Shengwei Jiang, Zefang Wang, Kaifei Kang, Ju-Hyun Park, Helmuth Berger, László Forró, Kam Tuen Law, Jie Shan, Kin Fai Mak

    Time reversal and spatial inversion are two key symmetries for conventional Bardeen–Cooper–Schrieffer (BCS) superconductivity1. Breaking inversion symmetry can lead to mixed-parity Cooper pairing and unconventional superconducting properties1,2,3,4,5. Two-dimensional (2D) NbSe2 has emerged as a new non-centrosymmetric superconductor with the unique out-of-plane or Ising spin–orbit coupling (SOC)6,7,8,9. Here we report the observation of an unusual continuous paramagnetic-limited superconductor–normal metal transition in 2D NbSe2. Using tunelling spectroscopy under high in-plane magnetic fields, we observe a continuous closing of the superconducting gap at the upper critical field at low temperatures, in stark contrast to the abrupt first-order transition observed in BCS thin-film superconductors10,11,12. The paramagnetic-limited continuous transition arises from a large spin susceptibility of the superconducting phase due to the Ising SOC. The result is further supported by self-consistent mean-field calculations based on the ab initio band structure of 2D NbSe2. Our findings establish 2D NbSe2 as a promising platform to explore novel spin-dependent superconducting phenomena and device concepts1, such as equal-spin Andreev reflection13 and topological superconductivity14,15,16.

    更新日期:2018-04-30
  • Motorizing fibres with geometric zero-energy modes
    Nat. Mater. (IF 39.235) Pub Date : 2018-04-30
    Arthur Baumann, Antoni Sánchez-Ferrer, Leandro Jacomine, Philippe Martinoty, Vincent Le Houerou, Falko Ziebert, Igor M. Kulić

    Responsive materials1,2,3 have been used to generate structures with built-in complex geometries4,5,6, linear actuators7,8,9 and microswimmers10,11,12. These results suggest that complex, fully functional machines composed solely from shape-changing materials might be possible13. Nonetheless, to accomplish rotary motion in these materials still relies on the classical wheel and axle motifs. Here we explore geometric zero-energy modes to elicit rotary motion in elastic materials in the absence of a rigid wheel travelling around an axle. We show that prestrained polymer fibres closed into rings exhibit self-actuation and continuous motion when placed between two heat baths due to elastic deformations that arise from rotational-symmetry breaking around the rod's axis. Our findings illustrate a simple but robust model to create active motion in mechanically prestrained objects.

    更新日期:2018-04-30
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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