1. Science: Polarity compensation mechanisms on the perovskite surface KTaO3(001)The use of scanning probe microscopy and density functional theory by Martin Setvin (Corresponding author) of the Vienna University of Technology, et al. studied the compensation mechanism of the perovskite potassium niobate (KTaO3) (001) surface with increasing degrees of freedom. The surface that is cut in vacuum is fixed in place, but it can respond immediately to insulator-to-metal transitions and possible ferroelectric lattice distortions. Annealing in vacuum forms separate oxygen vacancies, then the top layer is completely rearranged into ordered KO and TaO2 stripe patterns. The best solution was ultimately found by forming a hydroxylated cover layer with the desired geometry and charge and then placed in water vapor.Polarity compensation mechanisms on the perovskite surface KTaO3(001) (Science, 2018, DOI:10.1126/science.aar2287)2. Science: Atomic-resolution transmission electron microscopy of electron beam-sensitive crystalline materialsDaliang Zhang, Kun Li, and Professor Han Yu (co-corresponding correspondents) of King Abdullah University of Science and Technology have developed a series of strategies to solve the current challenges of high-resolution imaging of electron beam sensitive materials. The group’s design method uses a direct observation electronic computation (DDEC) camera to analyze a series of electron beam sensitive materials including a variety of metal-organic framework materials on the premise of limiting the overall electron dose. Using this strategy, the researchers observed the coexistence of benzene rings in UiO-66 and surface ligand-free and surface ligand capping. Thus, the results demonstrate that transmission electron microscopy imaging of atomic resolution for electron beam sensitive materials can be achieved using the above strategy.Atomic-resolution transmission electron microscopy of electron beam-sensitive crystalline materials (Science, 2018, DOI: 10.1126/science.aao0865)3, Science: Infrared hyperbolic metasurface based on nanostructured van der Waals materialsRainer Hillenbrand (Corresponding author) et al. of the University of Basque, Spain developed a mid-infrared hyperbolic facet by nanostructured thin layers of hexahedral boron nitride that support deep subwavelength-scale phonon polaritons. In-plane hyperbolic dispersion spreads together. By applying infrared nano-imaging technology, the concave (irregular) wavefront of the divergent polarized beamlets can be seen, which represents the hallmark signature of the hyperbolic polaron. These results illustrate how near-field microscopy can be used to reveal the external wavefronts of polaritons in anisotropic materials and demonstrate that nanostructured van der Waals materials can form highly variable and compact platforms for hyperbolic infrared conversion devices and circuits.Infrared hyperbolic metasurface based on nanostructured van der Waals materials (Science, 2018, DOI:10.1126/science.aaq1704)4, Science: Wrapping with a splash: High-speed encapsulation with ultrathin sheetsThe elastic film can rely on the hair suction to create an independent package on the droplets, and the intuitive observation of the process is very important. Narayanan Menon (Corresponding author) of the University of Massachusetts, USA, studied the inclusion of oil droplets in ultra-thin polymer films in the aqueous phase. The researchers obtained the 3D shape of the coating layer by polymerizing the 2D cutting edge of the film, and demonstrated the universality of the technology through both water-in-oil and oil-in-water films.Wrapping with a splash: High-speed encapsulation with ultrathin sheets (Science, 2018, DOI: 10.1126/science.aao1290)5. Nature: Catalytic assembly-point functionalization of carbyne equivalents with substitute chemicalsMarcos G. Suero (Corresponding author) and others of the Barcelona Institute of Science and Technology have realized that the intrinsic feature of carbyne is the continuous formation of three new covalent bonds. It is speculated that catalytic methods that produce carbon alkyne or other carbon forms that are relatively stable can This is achieved by constructing an assembly point separation method for a chiral center. The research group designed a new catalytic method that utilizes a visible light photo-oxidation-reduction catalyst to generate diazomethyl free radicals as analogs for carbyne. These carbyne analogs can induce site selection for carbon-hydrogen bond cleavage on the aromatic ring, resulting in an effective diazomethane methylation reaction, which can stabilize the sequencing control of the functionalization of late-stage assembly of pharmaceutical chemicals. This method provides an effective path for bioactive molecules to adjust the site of the chiral center, and can also perform an effective post-functionalization process.Catalytic assembly-point functionalization of carbyne equivalents with substitute chemicals (Nature, 2018, doi:10.1038/nature25185)6. Nature: Processing bulk natural wood into a high-performance structural materialThe University of Maryland Hu Liangbing and Teng Li (Common Communications) and others have developed a simple and effective strategy to directly convert blocky natural wood into high-performance structural materials with a tenfold increase in strength, toughness and ballistic resistance. Greater dimensional stability. Partial removal of lignin and hemicellulose from natural wood by boiling in an aqueous mixture of NaOH and Na2SO3, followed by hot pressing, results in the complete collapse of cell walls and complete densification of natural wood and highly consistent cellulose nanofibers. . This strategy has proven to be universally valid for all types of wood, which has a higher specific strength than most structural metals and alloys, making it a low-cost, high-performance, lightweight alternative.Processing bulk natural wood into a high-performance structural material (Nature, 2018, DOI:10.1038/nature25476)7. Nature: A new discovery of crystal disordered transformation to eliminate defectsThe article entitled “Freezing on a sphere” by the team of Paul M. Chaikin (Corresponding author) of New York University shows that the freezing of the sphere surface is formed by forming a single, “continent” containing crystals, which forcefully divides the defects into parts. 12 isolated “oceans.” Using this broken symmetry – align the vertices of the icosahedron with the defect “sea” and unfold these faces onto a plane and construct a new ordered parameter to reveal the potential long-range orientation order of the lattice. The effect of geometry on crystallization can be taken into account in the design of nanoscale and microscale structures in which movable defects are segregated into self-aligned arrays. In addition, the separation of defects at symmetrical locations and the concomitant mobility near these locations have been shown to be useful when designing specific regions for structures that require rigidity and flowability.References: Freezing on a sphere (Nature, 2018, DOI: 10.1038/nature25468)8, Nature: Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfideNorthwestern University Mark C. Hersam (Corresponding author) and others used polycrystalline single-layer molybdenum disulfide (MoS2) to experimentally implement multi-terminal hybrid memory resistors and transistors. Two-dimensional MoS2 memristors exhibit gated adjustability in a single resistive state. In addition, the six-terminal MoS2 memristor transistor also has a gated heterogeneity synapse function. The device helps to study complex neuromorphological learning and defect dynamics in two-dimensional materials.Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfide (Nature, 2018, DOI:10.1038/nature25747)9, Nature: Skin electronics from scalable fabrication of an intrinsically stretchable transistor arrayProf. Bao Zhennan (Corresponding author) of Stanford University designed a method for mass production and uniform preparation of various intrinsic extensible electronic polymers. The prepared electronic equipment can realize intrinsic elastic polymer transistor arrays. Density up to 347 transistors per square centimeter. At the same time, the conductivity and sensitivity of the transistor, which stretches the strain 1000 times, have not decreased significantly. It is possible to construct elastic stretchable electronic skin with sensor arrays and digital circuits. The reported preparation method can also be applied to the application of other intrinsic elastic polymer materials to prepare a new generation of elastic stretchable electronic skin devices.Skin electronics from scalable fabrication of an intrinsically stretchable transistor array (Nature, 2018, DOI: 10.1038/nature25494)
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