查看更多>>摘要：The γ-ray emission from the W51 complex is widely acknowledged to be attributed to the interaction between the cosmic rays(CRs)accelerated by the shock of supernova remnant(SNR)W51C and the dense molecular clouds in the adjacent star-forming region,W51B.However,the maximum acceleration capa-bility of W51C for CRs remains elusive.Based on observations conducted with the Large High Altitude Air Shower Observatory(LHAASO),we report a significant detection of γ rays emanating from the W51 com-plex,with energies from 2 to 200 TeV.The LHAASO measurements,for the first time,extend the y-ray emission from the W51 complex beyond 100 TeV and reveal a significant spectrum bending at tens of TeV.By combining the"π0-decay bump"featured data from Fermi-LAT,the broadband y-ray spectrum of the W51 region can be well-characterized by a simple pp-collision model.The observed spectral bend-ing feature suggests an exponential cutoff at～400 TeV or a power-law break at～200 TeV in the CR pro-ton spectrum,most likely providing the first evidence of SNRs serving as CR accelerators approaching the PeV regime.Additionally,two young star clusters within W51B could also be theoretically viable to pro-duce the most energetic γ rays observed by LHAASO.Our findings strongly support the presence of extreme CR accelerators within the W51 complex and provide new insights into the origin of Galactic CRs.
查看更多>>摘要：Host-less lithium metal anode generally suffers from large volume changes and serious dendrite growth during cycling,which poses challenges for its practical application.Interpenetrating phase composites with continuous architectures offer a solution to enhance mechanical properties of materials.Herein,a robust composite Li anode(LBN)material is fabricated through the metallurgical reaction between Li and hexagonal boron nitride(h-BN)with the formation of interpenetrating LiB/Li3BN2 phases.As LiB fibers are anchored by Li3BN2 granules,the collapse and slippage of LiB fibers are suppressed whilst the mechanical strength and structural stability of LBN are reinforced.By rolling,ultrathin(15 pm),free-standing,and electrochemically stable LBN foil can be obtained.The LBN anode exhibits a high average Coulombic efficiency of 99.69％(1 mA cm-2,3 mAh cm-2)and a long lifespan of 2500 h(1 mA cm-2,1 mAh cm-2).Notably,the LiCoO2(with double-sided load 40 mg cm-2)|LBN pouch cell can operate over 450 cycles with a capacity retention of 90.1％.The exceptional cycling stability of LBN can be ascribed to the interpenetrating reinforcement architectures and synergistic electronic/ionic conductivity of the LiB/Li3BN2 dual-lithiophilic-phases.This work provides a new methodology for thin Li strip processing and reinforced-architecture design,with implications beyond battery applications.
查看更多>>摘要：The stabilization of the formamidinium lead iodide(FAPbI3)structure is pivotal for the development of efficient photovoltaic devices.Employing two-dimensional(2D)layers to passivate the three-dimensional(3D)perovskite is essential for maintaining the α-phase of FAPbI3 and enhancing the power conversion efficiency(PCE)of perovskite solar cells(PSCs).However,the role of bulky ligands in the phase management of 2D perovskites,crucial for the stabilization of FAPbI3,has not yet been elucidated.In this study,we synthesized nanoscale 2D perovskite capping crusts with<n>=1 and 2 Ruddlesden-Popper(RP)perovskite layers,respectively,which form a type-Ⅱ2D/3D heterostructure.This heterostruc-ture stabilizes the α-phase of FAPbI3,and facilitates ultrafast carrier extraction from the 3D perovskite network to transport contact layer.We introduced tri-fluorinated ligands to mitigate defects caused by the halide vacancies and uncoordinated Pb2+ions,thereby reducing nonradiative carrier recombination and extending carrier lifetime.The films produced were incorporated into PSCs that not only achieved a PCE of 25.39％but also maintained 95％of their initial efficiency after 2000 h of continuous light expo-sure without encapsulation.These findings underscore the effectiveness of a phase-pure 2D/3D heterostructure-terminated film in inhibiting phase transitions passivating the iodide anion vacancy defects,facilitating the charge carrier extraction,and boosting the performance of optoelectronic devices.
查看更多>>摘要：The vertical phase distribution of active layers plays a vital role in balancing exciton dissociation and charge transport for achieving efficient polymer solar cells(PSCs).The layer-by-layer(LbL)PSCs are com-monly prepared by using sequential spin-coating method from donor and acceptor solutions with dis-tinct solvents and solvent additives.The enhanced exciton dissociation is expected in the LbL PSCs with efficient charge transport in the relatively neat donor or acceptor layers.In this work,a series of LbL all-polymer solar cells(APSCs)were fabricated with PM6 as donor and PY-DT as acceptor,and triplet material m-Ir(CPmPB)3 is deliberately incorporated into PY-DT layer to prolong exciton lifetimes of active layers.The power conversion efficiency(PCE)of LbL APSCs is improved to 18.24％from 17.32％by incorporating 0.3 wt％m-Ir(CPmPB)3 in PY-DT layer,benefiting from the simultaneously enhanced short-circuit current density(Jsc)of 25.17 mA cm-2 and fill factor(FF)of 74.70％.The enhancement of PCE is attributed to the efficient energy transfer of m-Ir(CPmPB)3 to PM6 and PY-DT,resulting in the prolonged exciton lifetime in the active layer and the increased exciton diffusion distance.The efficient energy transfer from m-Ir(CPmPB)3 to PM6 and PY-DT layer can be confirmed by the increased photo-luminescence(PL)intensity and the prolonged PL lifetime of PM6 and PY-DT in PM6+m-Ir(CPmPB)3 and PY-DT+m-Ir(CPmPB)3 films.This study indicates that the triplet material as solid additive has great potential in fabricating efficient LbL APSCs by prolonging exciton lifetimes in active layers.
查看更多>>摘要：Electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)to 2,5-furandicarboxylic acid(FDCA),a sus-tainable strategy to produce bio-based plastic monomer,is always conducted in a high-concentration alkaline solution(1.0 mol L-1 KOH)for high activity.However,such high concentration of alkali poses challenges including HMF degradation and high operation costs associated with product separation.Herein,we report a single-atom-ruthenium supported on Co3O4(Ru1-Co3O4)as a catalyst that works effi-ciently in a low-concentration alkaline electrolyte(0.1 mol L-1 KOH),exhibiting a low potential of 1.191 V versus a reversible hydrogen electrode to achieve 10 mA cm-2 in 0.1 mol L-1 KOH,which outperforms previous catalysts.Electrochemical studies demonstrate that single-atom-Ru significantly enhances hydroxyl(OH-)adsorption with insufficient OH-supply,thus improving HMF oxidation.To showcase the potential of Ru1-Co3O4 catalyst,we demonstrate its high efficiency in a flow reactor under industrially relevant conditions.Eventually,techno-economic analysis shows that substitution of the conventional 1.0 mol L-1 KOH with 0.1 mol L-1 KOH electrolyte may significantly reduce the minimum selling price of FDCA by 21.0％.This work demonstrates an efficient catalyst design for electrooxidation of biomass working without using strong alkaline electrolyte that may contribute to more economic biomass electro-valorization.
查看更多>>摘要：Elastic strain in Cu catalysts enhances their selectivity for the electrochemical CO2 reduction reaction(eCO2RR),particularly toward the formation of multicarbon(C2+)products.However,the reasons for this selectivity and the effect of catalyst precursors have not yet been clarified.Hence,we employed a redox strategy to induce strain on the surface of Cu nanocrystals.Oxidative transformation was employed to convert Cu nanocrystals to CuxO nanocrystals;these were subsequently electrochemically reduced to form Cu catalysts,while maintaining their compressive strain.Using a flow cell configuration,a current density of 1 A/cm2 and Faradaic efficiency exceeding 80％were realized for the C2+products.The selec-tivity ratio of C2+/C1 was also remarkable at 9.9,surpassing that observed for the Cu catalyst under tensile strain by approximately 7.6 times.In-situ Raman and infrared spectroscopy revealed a decrease in the coverage of K+ion-hydrated water(K·H2O)on the compressively strained Cu catalysts,consistent with molecular dynamics simulations and density functional theory calculations.Finite element method sim-ulations confirmed that reducing the coverage of coordinated K·H2O water increased the probability of intermediate reactants interacting with the surface,thereby promoting efficient C-C coupling and enhancing the yield of C2+products.These findings provide valuable insights into targeted design strate-gies for Cu catalysts used in the eCO2RR.
查看更多>>摘要：Ion channel activation upon ligand gating triggers a myriad of biological events and,therefore,evolution of ligand gating mechanism is of fundamental importance.TRPM2,a typical ancient ion channel,is acti-vated by adenosine diphosphate ribose(ADPR)and calcium and its activation has evolved from a simple mode in invertebrates to a more complex one in vertebrates,but the evolutionary process is still unknown.Molecular evolutionary analysis of TRPM2s from more than 280 different animal species has revealed that,the C-terminal NUDT9-H domain has evolved from an enzyme to a ligand binding site for activation,while the N-terminal MHR domain maintains a conserved ligand binding site.Calcium gat-ing pattern has also evolved,from one Ca2+-binding site as in sea anemones to three sites as in human.Importantly,we identified a new group represented by olTRPM2,which has a novel gating mode and fills the missing link of the channel gating evolution.We conclude that the TRPM2 ligand binding or activa-tion mode evolved through at least three identifiable stages in the past billion years from simple to com-plicated and coordinated.Such findings benefit the evolutionary investigations of other channels and proteins.
查看更多>>摘要：In medical image segmentation,it is often necessary to collect opinions from multiple experts to make the final decision.This clinical routine helps to mitigate individual bias.However,when data is annotated by multiple experts,standard deep learning models are often not applicable.In this paper,we propose a novel neural network framework called Multi-rater Prism(MrPrism)to learn medical image segmenta-tion from multiple labels.Inspired by iterative half-quadratic optimization,MrPrism combines the task of assigning multi-rater confidences and calibrated segmentation in a recurrent manner.During this pro-cess,MrPrism learns inter-observer variability while taking into account the image's semantic properties and finally converges to a self-calibrated segmentation result reflecting inter-observer agreement.Specifically,we propose Converging Prism(ConP)and Diverging Prism(DivP)to iteratively process the two tasks.ConP learns calibrated segmentation based on multi-rater confidence maps estimated by DivP,and DivP generates multi-rater confidence maps based on segmentation masks estimated by ConP.Experimental results show that the two tasks can mutually improve each other through this recur-rent process.The final converged segmentation result of MrPrism outperforms state-of-the-art(SOTA)methods for a wide range of medical image segmentation tasks.The code is available at https://github.-com/WuJunde/MrPrism.
查看更多>>摘要：Rheumatoid arthritis(RA)is an inflammatory autoimmune disease triggered by antigenic peptides with environmental and genetic risk factors.It has been shown that antigen-specific targeting could be a promising therapeutical strategy for RA by restoring immune tolerance to self-antigens without compro-mising normal immunity.Citrullination of antigens enhances antigenic properties and induces autoim-mune responses.Here,we showed that citrullinated antigenic(citAg)vaccine ameliorated collagen-induced arthritis with decreased T-helper 1(Th1)and Th17 cells,downregulated proinflammatory cytokines including interlukin-6 and tumor necrosis factor-α,and inhibited antigen recall responses.B cell receptor sequencing further revealed that citAg vaccine could dampen the dysregulated V(D)J recom-bination,restoring the immune repertoire.Taken together,the results demonstrated that citAg vaccine might have a therapeutic effect on RA.
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