Novel topological phases of matter are fruitful platforms for the discovery of unconventional electromagnetic phenomena. Higher-fold topology is one example, where the low-energy description goes ...beyond standard model analogs. Despite intensive experimental studies, conclusive evidence remains elusive for the multigap topological nature of higher-fold chiral fermions. In this Letter, we leverage a combination of fine-tuned chemical engineering and photoemission spectroscopy with photon energy contrast to discover the higher-fold topology of a chiral crystal. We identify all bulk branches of a higher-fold chiral fermion for the first time, critically important for allowing us to explore unique Fermi arc surface states in multiple interband gaps, which exhibit an emergent ladder structure. Through designer chemical gating of the samples in combination with our measurements, we uncover an unprecedented multigap bulk boundary correspondence. Our demonstration of multigap electronic topology will propel future research on unconventional topological responses.
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From the view of nanostructures, hierarchical lamellar heterostructures are one of the ideal candidates for high-performance electrode materials. Herein, hierarchical lamellar Co3O4–CoMoO4 ...heterostructures (Co3O4–CoMoO4 HLHs) are synthesized via a facile solvothermal approach with subsequent annealing treatment. The obtained HLHs consist of lamellar parallel stacked CoMoO4 nanosheets, where Co3O4 nanoflakes uniformly grow into an array on the surface of CoMoO4 nanosheets. The formation mechanism of Co3O4–CoMoO4 HLHs can be attributed to the sequential precipitation of CoMoO4 and Co3O4 precursors during the solvothermal process. The early nucleated parallel stacked 2D nanosheets serve as templates for the growth of Co hydroxide nanoflake arrays. Owing to the structural advantage, the as-obtained Co3O4–CoMoO4 HLHs endow the constructed electrode with enhanced electrochemical activity, high specific capacity and long-term cycling stability.
Superconductors with kagome lattices have been identified for over 40 years, with a superconducting transition temperature Tc up to 7 K. Recently, certain kagome superconductors have been found to ...exhibit an exotic charge order, which intertwines with superconductivity and persists to a temperature being one order of magnitude higher than Tc. In this work, we use scanning tunneling microscopy to study the charge order in kagome superconductor Rb V3 Sb5. We observe both a 2×2 chiral charge order and nematic surface superlattices (predominantly 1×4). We find that the 2×2 charge order exhibits intrinsic chirality with magnetic field tunability. Defects can scatter electrons to introduce standing waves, which couple with the charge order to cause extrinsic effects. While the chiral charge order resembles that discovered in KV3 Sb5, it further interacts with the nematic surface superlattices that are absent in KV3 Sb5 but exist in Cs V3 Sb5.
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The manipulation of topological states in quantum matter is an essential pursuit of fundamental physics and next-generation quantum technology. Here we report the magnetic manipulation of Weyl ...fermions in the kagome spin-orbit semimetal Co_{3}Sn_{2}S_{2}, observed by high-resolution photoemission spectroscopy. We demonstrate the exchange collapse of spin-orbit-gapped ferromagnetic Weyl loops into paramagnetic Dirac loops under suppression of the magnetic order. We further observe that topological Fermi arcs disappear in the paramagnetic phase, suggesting the annihilation of exchange-split Weyl points. Our findings indicate that magnetic exchange collapse naturally drives Weyl fermion annihilation, opening new opportunities for engineering topology under correlated order parameters.
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The emerging outbreak of monkeypox is closely associated with the viral infection and spreading, threatening global public health. Virus‐induced cell migration facilitates viral transmission. ...However, the mechanism underlying this type of cell migration remains unclear. Here we investigate the motility of cells infected by vaccinia virus (VACV), a close relative of monkeypox, through combining multi‐omics analyses and high‐resolution live‐cell imaging. We find that, upon VACV infection, the epithelial cells undergo epithelial–mesenchymal transition‐like transformation, during which they lose intercellular junctions and acquire the migratory capacity to promote viral spreading. After transformation, VACV‐hijacked RhoA signaling significantly alters cellular morphology and rearranges the actin cytoskeleton involving the depolymerization of robust actin stress fibers, leading‐edge protrusion formation, and the rear‐edge recontraction, which coordinates VACV‐induced cell migration. Our study reveals how poxviruses alter the epithelial phenotype and regulate RhoA signaling to induce fast migration, providing a unique perspective to understand the pathogenesis of poxviruses.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Materials with promising mechanical performance generally demonstrate requirements for the critical sizes of their key building units,
e.g.
entanglements and crystal grains. Herein, only with van der ...Waals interaction, viscoelasticity with broad tunability has been facilely achieved below the critical size limits: the dimers of ∼1 nm polyhedral oligomeric silsesquioxane (POSS) with
M
w
< 4 kD and size < 5 nm, which demonstrate distinct material physics compared to that of polymer nanocomposites of POSS. The dimeric POSSs are confirmed by scattering and calorimetrical measurements to be intrinsic glassy materials with glass transition temperatures (
T
g
s) lower than room temperature. From rheological studies, their viscoelasticity can be broadly tuned through the simple tailoring of the dimer linker structures above their
T
g
. In dimer bulks, each POSS cluster is spatially confined by the POSSs from other dimers and therefore, the correlation of the dynamics of the two linked POSS clusters, which, as indicated by dynamics analysis, is regulated by the length and flexibilities of linkers, contributes to the caging dynamics of POSS confined by their neighbours and the resulting unique viscoelasticity. Our discoveries update the understanding of the structural origin of viscoelasticity and open avenues to fabricate structural materials from the design of sub-nanoscale building blocks.
The critical size limit for general structural material design is challenged in the dimers of sub-nm molecular clusters that possess small sizes (<5 nm) and broadly tunable viscoelasticity.
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47.
Russian-Doll-Like Molecular Cubes Liu, Die; Li, Kaixiu; Chen, Mingzhao ...
Journal of the American Chemical Society,
02/2021, Volume:
143, Issue:
6
Journal Article
Peer reviewed
Nanosized cage-within-cage compounds represent a synergistic molecular self-assembling form of three-dimensional architecture that has received particular research focus. Building multilayered ...ultralarge cages to simulate complicated virus capsids is believed to be a tough synthetic challenge. Here, we synthesize two large double-shell supramolecular cages by facile self-assembly of presynthesized metal–organic hexatopic terpyridine ligands with metal ions. Differing from the mixture of prisms formed from the inner tritopic ligand, the redesigned metal–organic hexatopic ligands bearing high geometric constraints that led to the exclusive formation of discrete double-shell structures. These two unique nested cages are composed of inner cubes (5.1 nm) and outer huge truncated cubes (12.0 and 13.2 nm) with six large bowl-shape subcages distributed on six faces. The results with molecular weights of 75 232 and 77 667 Da were among the largest synthetic cage-in-cage supramolecules reported to date. The composition, size and shape were unambiguously characterized by a combination of 1H NMR, DOSY, ESI-MS, TWIM-MS, TEM, AFM, and SAXS. This work provides an interesting model for functional recognition, delivery, and detection of various guest molecules in the field of supramolecular materials.
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Single‐atom catalysts have drawn considerable attention because of their unique catalytic properties. However, the high surface energy of single atoms restricts their fabrication and creates ...significant challenges for further developments. In order to overcome this problem, metal organic framework (MOF)‐derived carbon materials can be served as ideal supports to anchor atomically dispersed metal atoms, due to their tunable particle size and shape features, by providing high surface area, porosity, thermal, and chemical stability. This review highlights the recent advances in i) different types of construction strategies for MOF‐derived carbon‐supported single‐atom catalysts, and ii) the catalytic applications of these MOF‐derived carbon‐supported single‐atom catalysts. Further, this review offers a valuable insight into the current challenges and future opportunities for MOF‐derived carbon‐supported single‐atom catalysts.
Metal organic framework (MOF)‐derived carbon materials are ideal supports to anchor atomically dispersed metal atoms. This review highlights the recent advances in the construction strategies and catalytic applications of the MOF‐derived carbon‐supported single‐atom catalysts. Further, this review offers a valuable insight into the current challenges and future opportunities in this rapidly ongoing area.
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The development of stimuli‐responsive circularly polarized luminescence (CPL) materials is quite attractive but challenging. Here, a pair of atomically precise enantiomers R/S‐Ag20 nanoclusters has ...been synthesized using chiral acid ligands. And then, stimuli‐responsive CPL materials were developed by assembling the chiral silver nanoclusters with an achiral bridging ligand. The atomically precise silver cluster‐assembled materials produce CPL with a dissymmetry factor (|glum|) of 1 × 10−3, through the high‐efficiency chiral induction process. More interestingly, the single CPL band at room temperature could quickly transform into highly separated dual CPL emissions at low temperature. This study provides a new strategy for the rational functionalization of chiral silver clusters in preparing cluster‐based CPL emitters and enriches the types of stimuli‐responsive CPL materials.
The temperature‐triggered dynamic circularly polarized luminescence materials were constructed by the coordination assembly of chiral silver nanoclusters and luminophor linkers.
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Hydrogen sulfide (H2S) is highly toxic and corrosive, and its selective removal from fuel and flue gases is of significance. It is a challenge to develop a dual-role material for efficient H2S ...capture as well as selective H2S oxidation. In the present work, we designed a class of nitrogen-decorated ordered mesoporous carbon spheres (denoted herein as N-OMCS-T, where T stands for carbonization temperature) for such an end. The N-OMCS-T with ordered mesopores are large in BET surface area (1201–1500 m2/g), and enriched with nitrogen sites of pyridinic and pyrrolic nature, and exhibit strong interaction with H2S as verified in DFT calculations. With large BET surface areas, ordered mesopores, and abundant nitrogen sites, the N-OMCS-T materials show extraordinary efficacy for the capture of H2S: H2S capacities are up to 13.4 mmol/g (0 °C, 1 bar), and the Ideal Adsorption Solution Theory selectivity in cases of H2S/CO2, H2S/CH4, and H2S/N2 is 2.1–8.5, 11.0–25.5, and 30.4–81.7, respectively, much higher than those of porous materials such as activated carbon, OMCS, Zeolite A, UiO-66, and SBA-15. Moreover, N-OMCS-T could act as efficient and long-lived metal-free catalysts for selective oxidation of the captured H2S to sulfur under mild conditions.
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