查看更多>>摘要：Quantum Hall effect,the quantized transport phenomenon of electrons under strong magnetic fields,remains one of the hottest research topics in condensed matter physics since its discovery in 2D elec-tronic systems.Recently,as a great advance in the research of quantum Hall effects,the quantum Hall effect in 3D systems,despite its big challenge,has been achieved in the bulk ZrTe5 and Cd3As2 materials.Interestingly,Cd3As2 is a Weyl semimetal,and quantum Hall effect is hosted by the Fermi arc states on opposite surfaces via the Weyl nodes of the bulk,and induced by the unique edge states on the bound-aries of the opposite surfaces.However,such intriguing edge state distribution has not yet been experi-mentally observed.Here,we aim to reveal experimentally the unusual edge states of Fermi arcs in acoustic Weyl system with the aid of pseudo-magnetic field.Benefiting from the macroscopic nature of acoustic crystals,the pseudo-magnetic field is introduced by elaborately designed the gradient on-site energy,and the edge states of Fermi arcs on the boundaries of the opposite surfaces are unambigu-ously demonstrated in experiments.Our system serves as an ideal and highly tunable platform to explore the Hall physics in 3D system,and has the potential in the application of new acoustic devices.
查看更多>>摘要：Exceptional bound(EB)states represent a unique new class of robust bound states protected by the defectiveness of non-Hermitian exceptional points.Conceptually distinct from the more well-known topological states and non-Hermitian skin states,they were recently discovered as a novel source of neg-ative entanglement entropy in the quantum entanglement context.Yet,EB states have been physically elusive,being originally interpreted as negative probability eigenstates of the propagator of non-Hermitian Fermi gases.In this work,we show that EB states are in fact far more ubiquitous,also arising robustly in broad classes of systems whether classical or quantum.This hinges crucially on a newly-discovered spectral flow that rigorously justifies the EB nature of small candidate lattice systems.As a highlight,we present their first experimental realization through an electrical circuit,where they man-ifest as prominent stable resonant voltage profiles.Our work brings a hitherto elusive but fundamentally distinctive quantum phenomenon into the realm of classical metamaterials,and provides a novel path-way for the engineering of robust modes in otherwise sensitive systems.
查看更多>>摘要：There is a pressing demand for the development of novel birefringent crystals tailored for compact optical components,especially for crystals exhibiting large birefringence across a range of temperatures.This has commonly been achieved by introducing various deformable groups with high polarizability anisotropy.In this study,we combined both rigid and deformable groups to synthesise a new birefringent crystal,Al2Te2MoO10,which demonstrates an exceptional birefringence value of 0.29@550 nm at room temper-ature.Not only is this higher birefringence than that of commercial crystals,but Al2Te2MoO10 exhibits excellent birefringence stability over a wide temperature range,from 123 to 503 K.In addition,the first-principles theory calculations and structural analyses suggest that although the rigid AlO6 groups do not make much contribution to the prominent birefringence,they nonetheless played a role in main-taining the structural anisotropy at elevated temperatures.Based on these findings,this paper proposes a novel structural design strategy to complement conventional approaches for developing optimal birefrin-gent crystals under various environmental conditions.
查看更多>>摘要：Two-dimensional(2D)ordered carbon-nitrogen binary compounds(CxNy)show great potential in many fields owing to their diverse structures and outstanding properties.However,the scalable and selective synthesis of 2D CxNy compounds remain a challenge due to the variable C/N stoichiometry induced coex-istence of graphitic,pyridinic,and pyrrolic N species and the competitive growth of graphene.Here,this work systematically explored the mechanism of selective growth of a series of 2D ordered CxNy com-pounds,namely,the g-C3N4,C2N,C3N,and C5N,on various epitaxial substrates via first-principles calcu-lations.By establishing the thermodynamic phase diagram,it is revealed that the individualized surface interaction and symmetry match between 2D CxNy compounds and substrates together enable the selec-tive epitaxial growth of single crystal 2D CxNy compounds within distinct chemical potential windows of feedstock.The kinetics behaviors of the diffusion and attachment of the decomposed feedstock C/N atoms to the growing CxNy clusters further confirmed the feasibility of the substrate mediated selective growth of 2D CxNy compounds.Moreover,the optimal experimental conditions,including the temperature and partial pressure of feedstock,are suggested for the selective growth of targeted 2D CxNy compound on individual epitaxial substrates by carefully considering the chemical potential of carbon/nitrogen as the functional of experimental parameters based on the standard thermochemical tables.This work pro-vides an insightful understanding on the mechanism of selective epitaxial growth of 2D ordered CxNy compounds for guiding the future experimental design.
查看更多>>摘要：Flexible pressure sensors with high sensitivity and linearity are highly desirable for robot sensing and human physiological signal detection.However,the current strategies for stabilizing axial microstruc-tures(e.g.,micro-pyramids)are mainly susceptible to structural stiffening during compression,thereby limiting the realization of high sensitivity and linearity.Here,we report a bending-induced non-equilibrium compression process that effectively enhances the compressibility of microstructures,thereby crucially improving the efficiency of interfacial area growth of electric double layer(EDL).Based on this principle,we fabricate an iontronic flexible pressure sensor with vertical graphene(VG)array electrodes.Ultra-high sensitivity(185.09 kPa-1)and linearity(R2=0.9999)are realized over a wide pressure range(0.49 Pa-66.67 kPa).It also exhibits remarkable mechanical stability during compression and bending.The sensor is successfully employed in a robotic gripping task to recognize the targets of different materials and shapes based on a multilayer perception(MLP)neural network.It opens the door to realizing haptic sensing capabilities for robotic hands and prosthetic limbs.
查看更多>>摘要：Perovskite light-emitting diodes(PeLEDs)exhibit remarkable potential in the field of displays and solid-state lighting.However,blue PeLEDs,a key element for practical applications,still lag behind their green and red counterparts,due to a combination of strong nonradiative recombination losses and unoptimized device structures.In this report,we propose a buried interface modification strategy to address these challenges by focusing on the bottom-hole transport layer(HTL)of the PeLEDs.On the one hand,a mul-tifunctional molecule,aminoacetic acid hydrochloride(AACl),is introduced to modify the HTL/perovskite interface to regulate the perovskite crystallization.Experimental investigations and theoretical calcula-tions demonstrate that AACl can effectively reduce the nonradiative recombination losses in bulk per-ovskites by suppressing the growth of low-n perovskite phases and also the losses at the bottom interface by passivating interfacial defects.On the other hand,a self-assembly nanomesh structure is ingeniously developed within the HTLs.This nanomesh structure is meticulously crafted through the blending of poly-(9,9-dioctyl-fluorene-co-N-(4-butyl phenyl)diphenylamine)and poly(n-vinyl car-bazole),significantly enhancing the light outcoupling efficiency in PeLEDs.As a result,our blue PeLEDs achieve remarkable external quantum efficiencies,20.4％at 487 nm and 12.5％at 470 nm,which are among the highest reported values.Our results offer valuable insights and effective methods for achiev-ing high-performance blue PeLEDs.
查看更多>>摘要：The rhesus macaque(Macaca mulatta)is a crucial experimental animal that shares many genetic,brain organizational,and behavioral characteristics with humans.A macaque brain atlas is fundamental to biomedical and evolutionary research.However,even though connectivity is vital for understanding brain functions,a connectivity-based whole-brain atlas of the macaque has not previously been made.In this study,we created a new whole-brain map,the Macaque Brainnetome Atlas(MacBNA),based on the anatomical connectivity profiles provided by high angular and spatial resolution ex vivo diffusion MRI data.The new atlas consists of 248 cortical and 56 subcortical regions as well as their structural and functional connections.The parcellation and the diffusion-based tractography were evaluated with invasive neuronal-tracing and Nissl-stained images.As a demonstrative application,the structural con-nectivity divergence between macaque and human brains was mapped using the Brainnetome atlases of those two species to uncover the genetic underpinnings of the evolutionary changes in brain structure.The resulting resource includes:(1)the thoroughly delineated Macaque Brainnetome Atlas(MacBNA),(2)regional connectivity profiles,(3)the postmortem high-resolution macaque diffusion and T2-weighted MRI dataset(Brainnetome-8),and(4)multi-contrast MRI,neuronal-tracing,and histological images collected from a single macaque.MacBNA can serve as a common reference frame for mapping multifaceted features across modalities and spatial scales and for integrative investigation and character-ization of brain organization and function.Therefore,it will enrich the collaborative resource platform for nonhuman primates and facilitate translational and comparative neuroscience research.
查看更多>>摘要：Heparan sulfate proteoglycan 2(HSPG2)gene encodes the matrix protein Perlecan,and genetic inactivation of this gene creates mice that are embryonic lethal with severe neural tube defects(NTDs).We discovered rare genetic variants of HSPG2 in 10％cases compared to only 4％in controls among a cohort of 369 NTDs.Endorepellin,a peptide cleaved from the domain V of Perlecan,is known to promote angiogenesis and autophagy in endothelial cells.The roles of enderepellin in neurodevelopment remain unclear so far.Our study revealed that endorepellin can migrate to the neuroepithelial cells and then be recognized and bind with the neuroepithelia receptor neurexin in vivo.Through the endocytic pathway,the interac-tion of endorepellin and neurexin physiologically triggers autophagy and appropriately modulates the differentiation of neural stem cells into neurons as a blocker,which is necessary for normal neural tube closure.We created knock-in(KI)mouse models with human-derived HSPG2 variants,using sperm-like stem cells that had been genetically edited by CRISPR/Cas9.We realized that any HSPG2 variants that affected the function of endorepellin were considered pathogenic causal variants for human NTDs given that the severe NTD phenotypes exhibited by these KI embryos occurred in a significantly higher response frequency compared to wildtype embryos.Our study provides a paradigm for effectively con-firming pathogenic mutations in other genetic diseases.Furthermore,we demonstrated that using autop-hagy inhibitors at a cellular level can repress neuronal differentiation.Therefore,autophagy agonists may prevent NTDs resulting from failed autophagy maintenance and neuronal over-differentiation caused by deleterious endorepellin variants.
查看更多>>摘要：Expanding the network of connected and resilient protected areas(PAs)for climate change adaptation can help species track suitable climate conditions and safeguard biodiversity.This is often overlooked when expanding PAs and quantifying their benefits,resulting in an underestimate of the benefits of expanding PAs.We expanded PAs through terrestrial mammalian species distribution hotspots,Key Biodiversity Areas(KBAs),and wilderness areas.Then,we constructed climate connectivity networks using a resistance-based approach and further quantified the network resilience to propose resilient cli-mate response strategies in China.The results showed that existing PAs suffered from location biases with important biodiversity areas.The existing PAs represented about half of the KBAs and wilderness areas,yet only 12.08％of terrestrial mammalian species distribution hotspots were located within exist-ing PAs.Compared with the existing PA network,the network efficiency and resilience of the expanded PAs'climate connectivity increased to 1.80 times and 1.78 times,respectively.With 56％of the nodes remaining,the network efficiency of the expanded PAs was equivalent to that of the existing PAs with all nodes.The network resilience of preferentially protecting and restoring low human footprint patches was approximately 1.5-2 times that of the random scenario.These findings highlighted that confronted with the unoptimistic situation of global warming,nature conservation based on existing PAs was no longer optimal.It was critical to construct a connected and resilient conservation network relying on both important biodiversity areas and low human footprint patches.
查看更多>>摘要：A"once-in-a-millennium"super rainstorm battered Zhengzhou,central China,from 07/17/2021 to 07/22/2021(named"7.20"Zhengzhou rainstorm).It killed 398 people and caused billions of dollars in damage.A pressing question is whether rainstorms of this intensity can be effectively documented by geological archives to understand better their historical variabilities beyond the range of meteorological data.Here,four land snail shells were collected from Zhengzhou,and weekly to daily resolved snail shellδ18O records from June to September of 2021 were obtained by gas-source mass spectrometry and sec-ondary ion mass spectrometry.The daily resolved records show a dramatic negative shift between 06/18/2021 and 09/18/2021,which has been attributed to the"7.20"Zhengzhou rainstorm.Moreover,the measured amplitude of this shift is consistent with the theoretical value estimated from the flux balance model and instrumental data for the"7.20"Zhengzhou rainstorm.Our results suggest that the ultra-high resolution δ18O of land snail shells have the potential to reconstruct local synoptic scale rainstorms quantitatively,and thus fossil snail shells in sedimentary strata can be valuable material for investigating the historical variability of local rainstorms under different climate backgrounds.
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