查看更多>>摘要：The Jahn-Teller effect(JTE)arising from lattice-electron coupling is a fascinating phenomenon that profoundly affects important physical properties in a number of transition-metal compounds.Controlling JT distortions and their corresponding electronic structures is highly desirable to tailor the functionalities of materials.Here,we propose a local coordinate strategy to regulate the JTE through quantifying occupancy in the dz2 and dx2-y2 orbitals of Mn and scrutinizing the symmetries of the ligand oxygen atoms in MnO6 octahedra in LiMn2O4 and Li0.5Mn2O4.The effectiveness of such a strategy has been demonstrated by constructing P2-type NaLixMn1-xO2 oxides with different Li/Mn ordering schemes.In addition,this strategy is also tenable for most 3d transition-metal compounds in spinel and perovskite frameworks,indicating the universality of local coordinate strategy and the tunability of the lattice-orbital coupling in transition-metal oxides.This work demonstrates a useful strategy to regulate JT distortion and provides useful guidelines for future design of functional materials with specific physical properties.
查看更多>>摘要：Ni-rich LiNixCoyMn2O2(NCMxyz,x+y+z=1,x≥ 0.8)layered oxide materials are considered the main cathode materials for high-energy-density Li-ion batteries.However,the endless cracking of polycrystalline NCM materials caused by stress accelerates the loss of active materials and electrolyte decomposition,limiting the cycle life.Hence,understanding the chemo-mechanical evolution during(de)lithiation of NCM materials is crucial to performance improvement.In this work,an optical fiber withμε resolution is designed to in operando detect the stress evolution of a polycrystalline LiNi0.8Co0.1Mn0.1O2(P-NCM811)cathode during cycling.By integrating the sensor inside the cathode,the stress variation of P-NCM811 is completely transferred to the optical fiber.We find that the anisotropy of primary particles leads to the appearance of structural stress,inducing the formation of microcracks in polycrystalline particles,which is the main reason for capacity decay.The isotropy of primary particles reduces the structural stress of polycrystalline particles,eliminating the generation of microcracks.Accordingly,the P-NCM811 with an ordered arrangement structure delivered high electrochemical performance with capacity retention of 82％over 500 cycles.This work provides a brand-new perspective with regard to understanding the operando chemo-mechanical evolution of NCM materials during battery operation,and guides the design of electrode materials for rechargeable batteries.
查看更多>>摘要：Crystalline matters with periodically arranged atoms found wide applications in modern science and technology.To facilitate the design of new materials and the advancement of existing ones,accurate and efficient models without relying too much on known inputs for predicting the functionalities are essential.Here,we propose an analytical approach for such a purpose,with only the knowledge of the structural chemistry of crystals.Based on the electrostatic interaction between periodically arranged atoms,the 1st,2nd and 3rd derivatives of interatomic potential,respectively,enable a prediction of ten kinds in total of mechanical,acoustical and thermal properties.Over a thousand measurements are collected from～500 literatures,this results in the symmetric mean percentage error(SMPE)within±25％and the symmetric mean absolute percentage error(SMAPE)ranging from 22％～74％across all properties predicted,which further enables a revelation of bond characteristics as the most important but implicit origin for functionalities.
查看更多>>摘要：The current-carrying friction characteristics are crucial for the performance of a sliding electrical contact,which plays critical roles in numerous electrical machines and devices.However,these characteristics are influenced by multiple factors such as material surface quality,chemical reactions,and atmospheric environment,leading to a challenge for researchers to comprehensively consider these impacts.Structural superlubricity(SSL),a state of nearly zero friction and no wear between contact solid surfaces,provides an ideal experimental system for these studies.Here,with microscale graphite flakes on atomic-flattened Au surface under applied voltages,we observed two opposite friction phenomena,depending only on whether the edge of graphite flake was in contact with the Au substrate.When in contact the friction force would increase with an increasing voltage,otherwise,the friction force would decrease.Notably,when the voltage was turned off,the friction force quickly recovered to its original level,indicating the absence of wear.Through atmosphere control and molecular dynamics simulations,we revealed the mechanism to be the different roles played by the water molecules confined at the interface or adsorbed near the edges.Our experimental results demonstrate the remarkable tunable and robust frictional properties of SSL under an electrical field,providing an ideal system for the fundamental research of not only sliding electrical contacts,but also novel devices which demand tunable frictions.
查看更多>>摘要：The confinement of waves within a waveguide can enable directional transmission of signals,which has found wide applications in communication,imaging,and signal isolation.Extending this concept to static systems,where material deformation is piled up along a spatial trajectory,remains elusive due to the sensitivity of localized deformation to structural defects and impurities.Here,we propose a general framework to characterize localized static deformation responses in two-dimensional generic static mechanical metamaterials,by exploiting the duality between space in static systems and time in one-dimensional non-reciprocal wave systems.An internal time-reverse symmetry is developed by the space-time duality.Upon breaking this symmetry,quasi-static load-induced deformation can be guided to travel along a designated path,thereby realizing a stress guide.A combination of time-reverse and inversion symmetries discloses the parity-time symmetry inherent in static systems,which can be leveraged to achieve directional deformation shielding.The tailorable stress guides can find applications in various scenarios,ranging from stress shielding and energy harvesting in structural tasks to information processing in mechanical computing devices.
查看更多>>摘要：The stability of complex systems is profoundly affected by underlying structures,which are often modeled as networks where nodes indicate system components and edges indicate pairwise interactions between nodes.However,such networks cannot encode the overall complexity of networked systems with higher-order interactions among more than two nodes.Set structures provide a natural description of pairwise and higher-order interactions where nodes are grouped into multiple sets based on their shared traits.Here we derive the stability criteria for networked systems with higher-order interactions by employing set structures.In particular,we provide a simple rule showing that the higher-order interactions play a double-sided role in community stability—networked systems with set structures are stabilized if the expected number of common sets for any two nodes is less than one.Moreover,although previous knowledge suggests that more interactions(i.e.complexity)destabilize networked systems,we report that,with higher-order interactions,networked systems can be stabilized by forming more local sets.Our findings are robust with respect to degree heterogeneous structures,diverse equilibrium states and interaction types.
查看更多>>摘要：Neural networks demonstrate vulnerability to small,non-random perturbations,emerging as adversarial attacks.Such attacks,born from the gradient of the loss function relative to the input,are discerned as input conjugates,revealing a systemic fragility within the network structure.Intriguingly,a mathematical congruence manifests between this mechanism and the quantum physics'uncertainty principle,casting light on a hitherto unanticipated interdisciplinarity.This inherent susceptibility within neural network systems is generally intrinsic,highlighting not only the innate vulnerability of these networks,but also suggesting potential advancements in the interdisciplinary area for understanding these black-box networks.
查看更多>>摘要：Surgical robotics application in the field of minimally invasive surgery has developed rapidly and has been attracting increasingly more research attention in recent years.A common consensus has been reached that surgical procedures are to become less traumatic and with the implementation of more intelligence and higher autonomy,which is a serious challenge faced by the environmental sensing capabilities of robotic systems.One of the main sources of environmental information for robots are images,which are the basis of robot vision.In this review article,we divide clinical image into direct and indirect based on the object of information acquisition,and into continuous,intermittent continuous,and discontinuous according to the target-tracking frequency.The characteristics and applications of the existing surgical robots in each category are introduced based on these two dimensions.Our purpose in conducting this review was to analyze,summarize,and discuss the current evidence on the general rules on the application of image technologies for medical purposes.Our analysis gives insight and provides guidance conducive to the development of more advanced surgical robotics systems in the future.
查看更多>>摘要：Physical science has undergone an evolutional transition in research focus from solid bulks to surfaces,culminating in numerous prominent achievements.Currently,it is experiencing a new exploratory phase—interfacial science.Many a technology with a tremendous impact is closely associated with a functional interface which delineates the boundary between disparate materials or phases,evokes complexities that surpass its pristine comprising surfaces,and thereby unveils a plethora of distinctive properties.Such an interface may generate completely new or significantly enhanced properties.These specific properties are closely related to the interfacial states formed at the interfaces.Therefore,establishing a quantitative relationship between the interfacial states and their functionalities has become a key scientific issue in interfacial science.However,interfacial science also faces several challenges such as invisibility in characterization,inaccuracy in calculation,and difficulty in precise construction.To tackle these challenges,people must develop new strategies for precise detection,accurate computation,and meticulous construction of functional interfaces.Such strategies are anticipated to provide a comprehensive toolbox tailored for future interfacial science explorations and thereby lay a solid scientific foundation for several key future technologies.
查看更多>>摘要：Organ injuries,such as acute kidney injury,ischemic stroke,and spinal cord injury,often result in complications that can be life-threatening or even fatal.Recently,many nanomaterials have emerged as promising agents for repairing various organ injuries.In this review,we present the important developments in the field of nanomaterial-based repair medicine,herein referred to as'nanorepair medicine'.We first introduce the disease characteristics associated with different types of organ injuries and highlight key examples of relevant nanorepair medicine.We then provide a summary of existing strategies in nanorepair medicine,including organ-targeting methodologies and potential countermeasures against exogenous and endogenous pathologic risk factors.Finally,we offer our perspectives on current challenges and future expectations for the advancement of nanomedicine designed for organ injury repair.
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