The preferential proton reduction over zinc-ion deposition in aqueous batteries arises from dual yet conflicting roles of water as charge carrier and parasitic reactant,posing persistent interfacial challenges.Althoug...The preferential proton reduction over zinc-ion deposition in aqueous batteries arises from dual yet conflicting roles of water as charge carrier and parasitic reactant,posing persistent interfacial challenges.Although cosolvent engineering has shown promise in mitigating water activity through hydrogenbond network modulation,prevailing strategies remain limited by their narrow focus on electronic and functional group properties,neglecting the stereochemical influence on molecular assembly.In this work,we uncover how molecular chirality dictates the hierarchical organization of hydrogen-bonding networks between cosolvents and water,which is a critical but previously unrecognized determinant of interfacial stability.By interrogating enantiomeric pairs(L-/D-carnitine),we demonstrate that chiral constraints steer the spatial arrangement of hydration structures through stereoselective hydrogenbonding geometries.Combined spectroscopic and molecular dynamics analyses reveal that L-carnitine(L-CN)forms a three-dimensional hydrogen-bonded matrix with water,exhibiting superior directional connectivity relative to its D-isomer.This stereo-dependent architecture simultaneously reinforces Zn2+solvation shells via bridging H-bond interactions and generates a self-adaptive interfacial structure that kinetically isolates water from the zinc anode surface.This stereochemical optimization enables Zn||Zn symmetric cells with unprecedented cycling stability exceeding 2000 h at 0.5 mA cm^(-2)/0.5 mAh cm^(-2).Corresponding Zn||Cu asymmetric cells maintain a high average Coulombic efficiency of 99.7%over 500 cycles at 3.0 mA cm^(-2)/3.0 mAh cm^(-2).This study pioneers a stereochemical design framework for aqueous electrolytes,elucidating chiral recognition mechanisms in solvation structures and establishing molecular topology engineering as a transformative strategy for high-efficiency energy storage systems.展开更多
Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in v...Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in various photonic systems,and it guides the behavior of these singularities,including the generation and annihilation of BICs.This work theoretically reveals the simultaneous generation of two distinct polarization singularity types,which include off-Γaccidental BICs and Dirac-type band degeneracy points.The generation is driven by a quadratic degeneracy of symmetry-protected BICs in a photonic crystal slab.It should be noted that this is achieved through continuously tuning a geometric parameter without breaking symmetry.Importantly,the generation of both singularity types can be explained by the topological charge conservation law.This adherence ensures the stability of these singularities and allows for continuous tuning of their positions in momentum space by continuously tuning a geometric parameter while preserving symmetry.This study presents a novel framework for synthesizing and manipulating complex polarization states by combining polarization singularities from both BICs and band degeneracies and holds promise for application in other wave systems beyond photonics.展开更多
Soil microbiomes play a crucial role in maintaining ecological functions and are of great importance for soil health.Some of them could bring benefits to plants for growth promotion.Despite numerous studies have focus...Soil microbiomes play a crucial role in maintaining ecological functions and are of great importance for soil health.Some of them could bring benefits to plants for growth promotion.Despite numerous studies have focused on specific beneficial bacteria and their interactions with soils and plants,we still lack a comprehensive understanding of beneficial communities in plant–soil continuums and their responses to agricultural activities.To address this gap,we carried out a microcosm experiment using 16S rRNA amplicon sequencing to explore the effects of organic fertilization on beneficial communities in plant–soil continuums and assess their potential multifunctionality.Our findings reveal that organic fertilization had a positive impact on the beneficial functionality of bacterial communities in plant–soil continuums.This improvement was primarily attributed to the optimized soil physicochemical conditions resulting from organic fertilization.Additionally,organic fertilization increased the complexity of bacterial co-occurrence networks in both soils and the endosphere.Keystone taxa in the endosphere undergone a shift of functions toward pathogen suppression as the result of organic fertilization.Furthermore,this study revealed that plants exhibited a preference for internalizing beneficial bacteria over other type of bacteria.We also provided new insights for evaluating the multifunctionality of microbiomes,and found that the functionality of beneficial communities in plant–soil continuums is enhanced by organic fertilization.All these findings suggested that organic fertilization can be an effective strategy for maintaining plant and soil health.展开更多
Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enh...Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enhance their advantages and maximize their performance.This study presents a design for a dielectric metasurface that achieves dual-band BICs in the terahertz(THz)range.By adjusting two asym-metry parameters of the structure,independent control of the two symmetry-protected BICs is achieved.Fur-thermore,by varying the shape of the silicon holes,the design's robustness to geometric variations is demon-strated.Finally,the test results show that the figures of merit(FOMs)for both BICs reach 109.This work provides a new approach for realizing and tuning dual-frequency BICs,offering expanded possibilities for applications in multimode lasers,nonlinear optics,multi-channel filtering,and optical sensing.展开更多
Numerous experiments have been designed to investigate the Cosmic Dawn(CD)and Epoch of Reionization(EoR)by examining redshifted 21 cm emissions from neutral hydrogen.Detecting the global spectrum of redshifted 21 cm s...Numerous experiments have been designed to investigate the Cosmic Dawn(CD)and Epoch of Reionization(EoR)by examining redshifted 21 cm emissions from neutral hydrogen.Detecting the global spectrum of redshifted 21 cm signals is typically achieved through single-antenna experiments.However,this global 21 cm signal is deeply embedded in foreground emissions,which are about four orders of magnitude stronger.Extracting this faint signal is a significant challenge,requiring highly precise instrumental calibration.Additionally,accurately modelling receiver noise in single-antenna experiments is inherently complex.An alternative approach using a short-spacing interferometer is expected to alleviate these difficulties because the noise in different receivers is uncorrelated and averages to zero upon cross-correlation.The Short-spacing Interferometer Array for Global 21 cm Signal Detection(SIGMA)is an upcoming experiment aimed at detecting the global CD/EoR signal using this approach.We describe the SIGMA system with a focus on optimal antenna design and layout,and propose a framework to address cross-talk between antennas in future calibrations.The SIGMA system is intended to serve as a prototype to gain a better understanding of the system’s instrumental effects and to optimize its performance further.展开更多
Local precise drug delivery is conducive to improving therapeutic efficacy and minimizing off-target toxicity.Current local delivery approaches are focused mostly on superficial or postoperative tumor lesions,due to t...Local precise drug delivery is conducive to improving therapeutic efficacy and minimizing off-target toxicity.Current local delivery approaches are focused mostly on superficial or postoperative tumor lesions,due to the challenges posed by the inaccessibility of deep-seated tumors.Herein,we report a magnetic continuum soft robot capable of non-invasive and site-specific delivery of prodrug nanoassemblies-loaded hydrogel.The nanoassemblies are co-assembled from redox-responsive docetaxel prodrug and oxaliplatin prodrug,and subsequently embedded into a hydrogel matrix.The hydrogel precursor and crosslinker are synchronously delivered using the soft robot under magnetic guidance and in situ crosslinked at the gastric cancer lesions,forming a drug depot for sustained release and long-lasting treatment.As the hydrogel gradually degrades,the nanoassemblies are internalized by tumor cells.The redox response ability enables them to be selectively activatedwithin tumor cells to trigger the release of docetaxel and oxaliplatin,exerting a synergistic anti-tumor effect.We find that the combination effectively induces immunogenic cell death of gastric tumor,enhancing antitumor immune responses.This strategy offers an intelligent and controllable integration platform for precise drug delivery and combined chemo-immunotherapy.展开更多
Deconvolution in radio interferometry faces challenges due to incomplete sampling of the visibilities in the spatial frequency domain caused by a limited number of antenna baselines,resulting in an ill-posed inverse p...Deconvolution in radio interferometry faces challenges due to incomplete sampling of the visibilities in the spatial frequency domain caused by a limited number of antenna baselines,resulting in an ill-posed inverse problem.Reconstructing dirty images into clean ones is crucial for subsequent scientific analysis.To address these challenges,we propose a U-Net based method that extracts high-level information from the dirty image and reconstructs a clean image by effectively reducing artifacts and sidelobes.The U-Net architecture,consisting of an encoder-decoder structure and skip connections,facilitates the flow of information and preserves spatial details.Using simulated data of radio galaxies,we train our model and evaluate its performance on the testing set.Compared with the CLEAN method and the visibility and image conditioned denoising diffusion probabilistic model,our proposed model can effectively reconstruct both extended sources and faint point sources with higher values in the structural similarity index measure and the peak signal-to-noise ratio.Furthermore,we investigate the impact of noise on the model performance,demonstrating its robustness under varying noise levels.展开更多
The design and analysis of continuum robots have consistently been a prominent research focus in the field of mechanics.However,portable continuum robots with minimal spatial occupancy,which have great potential for a...The design and analysis of continuum robots have consistently been a prominent research focus in the field of mechanics.However,portable continuum robots with minimal spatial occupancy,which have great potential for applications such as search and rescue,are scarcely available.This paper presents a novel helical-coiled multi-segment flexible continuum robot featuring helical deployment and compact design,with an integrated framework for structural design,kinematic modeling,and experimental validation.The design of the helical-coiled multi-segment flexible continuum robot for unstructured environment detection,including a flexible body,an actuation module,a feed module,and a sensing module,is presented systematically.Kinematic models of both single-and multisegment continuum robots were established based on the constant curvature model to analyze the parameter mapping relationship from the end-effector position and orientation to the driving inputs.Furthermore,the feedforward motion of the robot was examined,and an uncoiling strategy based on S-curve compensation was employed to complete the kinematic analysis.Finally,the accuracy of the kinematic model considering the active uncoiling feed motion was validated through experimental analysis,demonstrating the motion characteristics of the continuum robot.Altogether,this study provides a framework for the design and analysis of helical-coiled continuum robots.展开更多
Introduction: Reducing and maintaining viral load is crucial to reducing morbidity and mortality associated with HIV infection in children. The aim of this study was to determine the factors influencing the maintenanc...Introduction: Reducing and maintaining viral load is crucial to reducing morbidity and mortality associated with HIV infection in children. The aim of this study was to determine the factors influencing the maintenance of children and adolescents on antiretroviral therapy in the continuum of care. Methodology: This was a descriptive and analytical cross-sectional study conducted from August 1 to August 31, 2023. It included all children living with HIV, under 15 years of age, with at least two viral load results and whose parents consented to participate in the study. Participants were recruited during their child’s treatment renewal consultations. Results: The study included 143 children, mostly boys (55.2%), with a mean age of 11.54 years (±2.8). More than half (55.2) were unaware of their HIV-positive status, and most treatments were administered by parents (60.8%). Of the 99 children with an undetectable viral load at the first test, 23 (23.2%) showed a viral rebound at the last test, mainly due to poor treatment compliance (p Conclusion: Virological rebound after suppression in children is worrying. It is crucial that the national AIDS program improves Therapeutic Education, trains health workers to communicate results and encourages ongoing dialogue with young people to reinforce adherence and maintain viral suppression.展开更多
Anaerobic ammonium oxidation coupled to iron(III)reduction(Feammox)process has recently been recognized as an important pathway for removing ammonium in various natural habitats.However,our understanding for Feammox i...Anaerobic ammonium oxidation coupled to iron(III)reduction(Feammox)process has recently been recognized as an important pathway for removing ammonium in various natural habitats.However,our understanding for Feammox in river–estuary continuum is limited.In this study,stable isotope tracers and high-throughput amplicon sequencing were employed to determine Feammox rates and identify associated microbial communities in sediments along the Yangtze river–estuary continuum.Feammox rates averaged 0.0058±0.0069 mg N/(kg·d)and accounted for approximately 22.3%of the ammonium removed from the sediments.Sediment Fe(III),ammonium(NH_(4)^(+)),total organic carbon(TOC),and pH were identified as important factors influencing Feammox rates.Additionally,Spirochaeta,Caldilineaceae_uncultured,and Ignavibacterium were found potentially associated with Feammox,which had not been documented as Feammox-associated microbial taxa previously.This study demonstrates that Feammox plays a vital role in ammonium removal within the Yangtze river–estuary continuum,providing greater insight into nitrogen removal and cycling in aquatic ecosystems.展开更多
This paper presents a continuum manipulator inspired by the anatomical characteristics of the elephant trunk.Specifically,the manipulator mimics the conoid profile of the elephant trunk,which helps to enhance its stre...This paper presents a continuum manipulator inspired by the anatomical characteristics of the elephant trunk.Specifically,the manipulator mimics the conoid profile of the elephant trunk,which helps to enhance its strength.The design features two concentric parts:inner pneumatically actuated bellows and an outer tendon-driven helical spring.The tendons control the omnidirectional bending of the manipulator,while the fusion of the pneumatic bellows with the tendon-driven spring results in an antagonistic actuation mechanism that provides the manipulator with variable stiffness and extensibility.This paper presents a new design for extensible manipulator and analyzes its stiffness and motion characteristics.Experimental results are consistent with theoretical analysis,thereby demonstrating the validity of the theoretical approach and the versatile practical mechanical properties of the continuum manipulator.The impressive extensibility and variable stiffness of the manipulator were further demonstrated by performing a pin-hole assembly task.展开更多
The resonance generated by different mechanisms naturally has different characteristics in sensing,and these differences increase the potential for specific detection.We designed a metasurface with both a quasi-bound ...The resonance generated by different mechanisms naturally has different characteristics in sensing,and these differences increase the potential for specific detection.We designed a metasurface with both a quasi-bound state in continuum(QBIC)resonance and dipole resonance by conducting physical analyses such as electric field,current distribution,and multiple expansions on a dual-split-ring resonance with dipole resonance and a variant structure with symmetry breaking.On the other hand,the edge length of the slit was extended through a tilted split design,which further enhanced the QBIC resonance signal of the metasurface.In the sensing experiment of hyaluronic acid(HA),the limit of detection(LOD)obtained through frequency shift was 0.958 pmol∕μL,whereas the LOD obtained through the change in transmittance was 0.02 pmol∕μL.Our research findings contribute to the design of multiple resonant metasurfaces with different resonance modes,promoting further development in metasurface research and biosensing.展开更多
Megahertz-peaked spectra(MPS)pulsars are referred as cases whose radio spectra turn over around 100 MHz.We identified 53 MPS pulsars based on the spectral data from the literature,and statistically analyzed the spatia...Megahertz-peaked spectra(MPS)pulsars are referred as cases whose radio spectra turn over around 100 MHz.We identified 53 MPS pulsars based on the spectral data from the literature,and statistically analyzed the spatial location distribution,the magnetic field-period distribution,peak frequencies,spectral indices,and dispersion measures of these MPS pulsars.We found that there is a strong positive correlation between the dispersion measures and the peak frequencies of MPS pulsars,and negative correlations of the dispersion measures with spectral indices and the ages are also found.Such correlations suggest that the interstellar medium is an important factor that affects observational properties of MPS pulsars.展开更多
In this study,an end-to-end deep learning method is proposed to improve the accuracy of continuum estimation in low-resolution gamma-ray spectra.A novel process for generating the theoretical continuum of a simulated ...In this study,an end-to-end deep learning method is proposed to improve the accuracy of continuum estimation in low-resolution gamma-ray spectra.A novel process for generating the theoretical continuum of a simulated spectrum is established,and a convolutional neural network consisting of 51 layers and more than 105 parameters is constructed to directly predict the entire continuum from the extracted global spectrum features.For testing,an in-house NaI-type whole-body counter is used,and 106 training spectrum samples(20%of which are reserved for testing)are generated using Monte Carlo simulations.In addition,the existing fitting,step-type,and peak erosion methods are selected for comparison.The proposed method exhibits excellent performance,as evidenced by its activity error distribution and the smallest mean activity error of 1.5%among the evaluated methods.Additionally,a validation experiment is performed using a whole-body counter to analyze a human physical phantom containing four radionuclides.The largest activity error of the proposed method is−5.1%,which is considerably smaller than those of the comparative methods,confirming the test results.The multiscale feature extraction and nonlinear relation modeling in the proposed method establish a novel approach for accurate and convenient continuum estimation in a low-resolution gamma-ray spectrum.Thus,the proposed method is promising for accurate quantitative radioactivity analysis in practical applications.展开更多
In the paper we derive new solutions for the discrete and continuous Schwarzian Korteweg–de Vries(SKd V)equations.These solutions are characterized by trigonometric functions as backgrounds.For the discrete SKd V equ...In the paper we derive new solutions for the discrete and continuous Schwarzian Korteweg–de Vries(SKd V)equations.These solutions are characterized by trigonometric functions as backgrounds.For the discrete SKd V equation,its solutions are derived by using trigonometric function seeds and B?cklund transformation.Solutions for the continuous SKd V equation are obtained by taking continuum limits.展开更多
Ionospheric scintillation behaves as the random fluctuation of amplitude and phase of the traveling electromagnetic wave caused by irregularities of the Earth ionosphere.In the radio waveband,it influences the perform...Ionospheric scintillation behaves as the random fluctuation of amplitude and phase of the traveling electromagnetic wave caused by irregularities of the Earth ionosphere.In the radio waveband,it influences the performance of satellite navigation systems and radio astronomy observations.Here,the 3.2 m radio telescope located at Sun Yat-sen University(SYSU 3.2 m radio telescope)in Zhuhai is used to observe the radio signal from the geosynchronous Earth orbit satellite C0_(3) of the Beidou navigation system at 1561.098±3 MHz.Fluctuations of intensity in the dynamic spectra,i.e.,the standard deviation S_(4)index,are analyzed to study the scintillation of the ionosphere.The results are compared with those from global navigation satellite system(GNSS)receivers and a GPStation-6 scintillation monitor located at the same place.GNSS receiver and GPStation-6 observations confirm the scintillation events observed by the SYSU 3.2 m radio telescope.The radio telescope observations provide insights into the impact of ionospheric scintillation on astronomical observations.展开更多
In this research,we introduce an innovative approach that combines the Continuum Damage Mechanics-Finite Element Method(CDM-FEM)with the Particle Swarm Optimization(PSO)-based technique,to predict the Medium-Low-Cycle...In this research,we introduce an innovative approach that combines the Continuum Damage Mechanics-Finite Element Method(CDM-FEM)with the Particle Swarm Optimization(PSO)-based technique,to predict the Medium-Low-Cycle Fatigue(MLCF)life of perforated structures.First,fatigue tests are carried out on three center-perforated structures,aiming to assess their fatigue life under various strengthening conditions.These tests reveal significant variations in fatigue life,accompanied by an examination of crack initiation through the analysis of fatigue fracture surfaces.Second,an innovative fatigue life prediction methodology is applied to perforated structures,which not only forecasts the initiation of fatigue cracks but also traces the progression of damage within these structures.It leverages an elastoplastic constitutive model integrated with damage and a damage evolution model under cyclic loads.The accuracy of this approach is validated by comparison with test results,falling within the three times error band.Finally,we explore the impact of various strengthening techniques,including cross-sectional reinforcement and cold expansion,on the fatigue life and damage evolution of these structures.This is achieved through an in-depth comparative analysis of both experimental data and computational predictions,which provides valuable insights into the behavior of perforated structures under fatigue conditions in practical applications.展开更多
A previous paper showed that the real numbers between 0 and 1 could be represented by an infinite tree structure, called the ‘infinity tree’, which contains only a countably infinite number of nodes and arcs. This p...A previous paper showed that the real numbers between 0 and 1 could be represented by an infinite tree structure, called the ‘infinity tree’, which contains only a countably infinite number of nodes and arcs. This paper discusses how a finite-state Turing machine could, in a countably infinite number of state transitions, write all the infinite paths in the infinity tree to a countably infinite tape. Hence it is argued that the real numbers in the interval [0, 1] are countably infinite in a non-Cantorian theory of infinity based on Turing machines using countably infinite space and time. In this theory, Cantor’s Continuum Hypothesis can also be proved. And in this theory, it follows that the power set of the natural numbers P(ℕ) is countably infinite, which contradicts the claim of Cantor’s Theorem for the natural numbers. However, this paper does not claim there is an error in Cantor’s arguments that [0, 1] is uncountably infinite. Rather, this paper considers the situation as a paradox, resulting from different choices about how to represent and count the continuum of real numbers.展开更多
The traditional topology optimization method of continuum structure generally uses quadrilateral elements as the basic mesh.This approach often leads to jagged boundary issues,which are traditionally addressed through...The traditional topology optimization method of continuum structure generally uses quadrilateral elements as the basic mesh.This approach often leads to jagged boundary issues,which are traditionally addressed through post-processing,potentially altering the mechanical properties of the optimized structure.A topology optimization method of Movable Morphable Smooth Boundary(MMSB)is proposed based on the idea of mesh adaptation to solve the problem of jagged boundaries and the influence of post-processing.Based on the ICM method,the rational fraction function is introduced as the filtering function,and a topology optimization model with the minimum weight as the objective and the displacement as the constraint is established.A triangular mesh is utilized as the base mesh in this method.The mesh is re-divided in the optimization process based on the contour line,and a smooth boundary parallel to the contour line is obtained.Numerical examples demonstrate that the MMSB method effectively resolves the jagged boundary issues,leading to enhanced structural performance.展开更多
A robust generalized continuum model called the wavelength-dependent strain gradient continuum model(WDSGM)has been proposed to predict dispersion properties of two-dimensional(2D)periodic lattice metamaterials.The ke...A robust generalized continuum model called the wavelength-dependent strain gradient continuum model(WDSGM)has been proposed to predict dispersion properties of two-dimensional(2D)periodic lattice metamaterials.The key idea lies in replacing the classical Taylor expansion of displacement fields with a wavelength-dependent one,naturally leading to new equations of motion and therefore a significantly improved capability of predicting dispersion characteristics.For different 2D lattices,dispersion results derived from the proposed WDSGM are verified by comparing with those obtained from the discrete model and the existing strain gradient continuum model(SGM)in the irreducible Brillouin zone.Based on the proposed model,the effects of SG orders have been investigated.Results suggest that considering the wavelength-dependent Taylor expansion and increasing the SG order are beneficial to improving the predictive performance of continuum models.The proposed model is free of any instability issue which is challenging for many existing SG methods.Under given parameters,the proposed WDSGM with eighth-order truncation is enough to predict the dispersion relation of three lattices,i.e.,the square,triangular and hexagonal lattices throughout the irreducible Brillouin zone.展开更多
基金supported by the National Natural Science Foundation of China(52402316)the Natural Science Foundation of Zhejiang Province(LQ23B030002)the Start-up Foundation of Zhejiang University of Science and Technology(ZUST)。
文摘The preferential proton reduction over zinc-ion deposition in aqueous batteries arises from dual yet conflicting roles of water as charge carrier and parasitic reactant,posing persistent interfacial challenges.Although cosolvent engineering has shown promise in mitigating water activity through hydrogenbond network modulation,prevailing strategies remain limited by their narrow focus on electronic and functional group properties,neglecting the stereochemical influence on molecular assembly.In this work,we uncover how molecular chirality dictates the hierarchical organization of hydrogen-bonding networks between cosolvents and water,which is a critical but previously unrecognized determinant of interfacial stability.By interrogating enantiomeric pairs(L-/D-carnitine),we demonstrate that chiral constraints steer the spatial arrangement of hydration structures through stereoselective hydrogenbonding geometries.Combined spectroscopic and molecular dynamics analyses reveal that L-carnitine(L-CN)forms a three-dimensional hydrogen-bonded matrix with water,exhibiting superior directional connectivity relative to its D-isomer.This stereo-dependent architecture simultaneously reinforces Zn2+solvation shells via bridging H-bond interactions and generates a self-adaptive interfacial structure that kinetically isolates water from the zinc anode surface.This stereochemical optimization enables Zn||Zn symmetric cells with unprecedented cycling stability exceeding 2000 h at 0.5 mA cm^(-2)/0.5 mAh cm^(-2).Corresponding Zn||Cu asymmetric cells maintain a high average Coulombic efficiency of 99.7%over 500 cycles at 3.0 mA cm^(-2)/3.0 mAh cm^(-2).This study pioneers a stereochemical design framework for aqueous electrolytes,elucidating chiral recognition mechanisms in solvation structures and establishing molecular topology engineering as a transformative strategy for high-efficiency energy storage systems.
基金supported by the National Natural Science Foundation of China(Nos.11974259 and 12274241)。
文摘Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in various photonic systems,and it guides the behavior of these singularities,including the generation and annihilation of BICs.This work theoretically reveals the simultaneous generation of two distinct polarization singularity types,which include off-Γaccidental BICs and Dirac-type band degeneracy points.The generation is driven by a quadratic degeneracy of symmetry-protected BICs in a photonic crystal slab.It should be noted that this is achieved through continuously tuning a geometric parameter without breaking symmetry.Importantly,the generation of both singularity types can be explained by the topological charge conservation law.This adherence ensures the stability of these singularities and allows for continuous tuning of their positions in momentum space by continuously tuning a geometric parameter while preserving symmetry.This study presents a novel framework for synthesizing and manipulating complex polarization states by combining polarization singularities from both BICs and band degeneracies and holds promise for application in other wave systems beyond photonics.
基金supported by the State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products(No.2021DG700024-KF202307).
文摘Soil microbiomes play a crucial role in maintaining ecological functions and are of great importance for soil health.Some of them could bring benefits to plants for growth promotion.Despite numerous studies have focused on specific beneficial bacteria and their interactions with soils and plants,we still lack a comprehensive understanding of beneficial communities in plant–soil continuums and their responses to agricultural activities.To address this gap,we carried out a microcosm experiment using 16S rRNA amplicon sequencing to explore the effects of organic fertilization on beneficial communities in plant–soil continuums and assess their potential multifunctionality.Our findings reveal that organic fertilization had a positive impact on the beneficial functionality of bacterial communities in plant–soil continuums.This improvement was primarily attributed to the optimized soil physicochemical conditions resulting from organic fertilization.Additionally,organic fertilization increased the complexity of bacterial co-occurrence networks in both soils and the endosphere.Keystone taxa in the endosphere undergone a shift of functions toward pathogen suppression as the result of organic fertilization.Furthermore,this study revealed that plants exhibited a preference for internalizing beneficial bacteria over other type of bacteria.We also provided new insights for evaluating the multifunctionality of microbiomes,and found that the functionality of beneficial communities in plant–soil continuums is enhanced by organic fertilization.All these findings suggested that organic fertilization can be an effective strategy for maintaining plant and soil health.
文摘Compared to traditional single-frequency bound states in the continuum(BIC),dual-band BIC of-fers higher degrees of freedom and functionality.Moveover,implementing independent control of dual-band BICs can further enhance their advantages and maximize their performance.This study presents a design for a dielectric metasurface that achieves dual-band BICs in the terahertz(THz)range.By adjusting two asym-metry parameters of the structure,independent control of the two symmetry-protected BICs is achieved.Fur-thermore,by varying the shape of the silicon holes,the design's robustness to geometric variations is demon-strated.Finally,the test results show that the figures of merit(FOMs)for both BICs reach 109.This work provides a new approach for realizing and tuning dual-frequency BICs,offering expanded possibilities for applications in multimode lasers,nonlinear optics,multi-channel filtering,and optical sensing.
基金supported by the National SKA Program of China(No.2020SKA0110200 and No.2020SKA0110100)Y.Y.acknowledges the support of the Key Program of National Natural Science Foundation of China(12433012)。
文摘Numerous experiments have been designed to investigate the Cosmic Dawn(CD)and Epoch of Reionization(EoR)by examining redshifted 21 cm emissions from neutral hydrogen.Detecting the global spectrum of redshifted 21 cm signals is typically achieved through single-antenna experiments.However,this global 21 cm signal is deeply embedded in foreground emissions,which are about four orders of magnitude stronger.Extracting this faint signal is a significant challenge,requiring highly precise instrumental calibration.Additionally,accurately modelling receiver noise in single-antenna experiments is inherently complex.An alternative approach using a short-spacing interferometer is expected to alleviate these difficulties because the noise in different receivers is uncorrelated and averages to zero upon cross-correlation.The Short-spacing Interferometer Array for Global 21 cm Signal Detection(SIGMA)is an upcoming experiment aimed at detecting the global CD/EoR signal using this approach.We describe the SIGMA system with a focus on optimal antenna design and layout,and propose a framework to address cross-talk between antennas in future calibrations.The SIGMA system is intended to serve as a prototype to gain a better understanding of the system’s instrumental effects and to optimize its performance further.
基金supported by National Natural Science Foundation of China(No.82161138029)Liaoning Revitalization Talents Program(No.XLYC2402040)the Project of China-Japan Joint International Laboratory of Advanced Drug Delivery System Research and Translation of Liaoning Province(No.2024JH2/102100007).
文摘Local precise drug delivery is conducive to improving therapeutic efficacy and minimizing off-target toxicity.Current local delivery approaches are focused mostly on superficial or postoperative tumor lesions,due to the challenges posed by the inaccessibility of deep-seated tumors.Herein,we report a magnetic continuum soft robot capable of non-invasive and site-specific delivery of prodrug nanoassemblies-loaded hydrogel.The nanoassemblies are co-assembled from redox-responsive docetaxel prodrug and oxaliplatin prodrug,and subsequently embedded into a hydrogel matrix.The hydrogel precursor and crosslinker are synchronously delivered using the soft robot under magnetic guidance and in situ crosslinked at the gastric cancer lesions,forming a drug depot for sustained release and long-lasting treatment.As the hydrogel gradually degrades,the nanoassemblies are internalized by tumor cells.The redox response ability enables them to be selectively activatedwithin tumor cells to trigger the release of docetaxel and oxaliplatin,exerting a synergistic anti-tumor effect.We find that the combination effectively induces immunogenic cell death of gastric tumor,enhancing antitumor immune responses.This strategy offers an intelligent and controllable integration platform for precise drug delivery and combined chemo-immunotherapy.
基金supported by the National SKA Program of China(2020SKA0110300,2020SKA0110201)the National Natural Science Foundation of China(NSFC,grant Nos.12433012 and 12373097)+1 种基金the Guangdong Province Project of the Basic and Applied Basic Research Foundation(2024A1515011503)the Guangzhou Science and Technology Funds(2023A03J0016).
文摘Deconvolution in radio interferometry faces challenges due to incomplete sampling of the visibilities in the spatial frequency domain caused by a limited number of antenna baselines,resulting in an ill-posed inverse problem.Reconstructing dirty images into clean ones is crucial for subsequent scientific analysis.To address these challenges,we propose a U-Net based method that extracts high-level information from the dirty image and reconstructs a clean image by effectively reducing artifacts and sidelobes.The U-Net architecture,consisting of an encoder-decoder structure and skip connections,facilitates the flow of information and preserves spatial details.Using simulated data of radio galaxies,we train our model and evaluate its performance on the testing set.Compared with the CLEAN method and the visibility and image conditioned denoising diffusion probabilistic model,our proposed model can effectively reconstruct both extended sources and faint point sources with higher values in the structural similarity index measure and the peak signal-to-noise ratio.Furthermore,we investigate the impact of noise on the model performance,demonstrating its robustness under varying noise levels.
基金Supported by National Natural Science Foundation of China(Grant Nos.52305003,52175019)National Key R&D Program of China(Grant No.2023YFD2001100)+2 种基金Beijing Natural Science Foundation(Grant No.L222038)Beijing Nova Programme Interdisciplinary Cooperation Project(Grant No.20240484699)Project“Vice President of Science and Technology”of Changping District of Beijing.
文摘The design and analysis of continuum robots have consistently been a prominent research focus in the field of mechanics.However,portable continuum robots with minimal spatial occupancy,which have great potential for applications such as search and rescue,are scarcely available.This paper presents a novel helical-coiled multi-segment flexible continuum robot featuring helical deployment and compact design,with an integrated framework for structural design,kinematic modeling,and experimental validation.The design of the helical-coiled multi-segment flexible continuum robot for unstructured environment detection,including a flexible body,an actuation module,a feed module,and a sensing module,is presented systematically.Kinematic models of both single-and multisegment continuum robots were established based on the constant curvature model to analyze the parameter mapping relationship from the end-effector position and orientation to the driving inputs.Furthermore,the feedforward motion of the robot was examined,and an uncoiling strategy based on S-curve compensation was employed to complete the kinematic analysis.Finally,the accuracy of the kinematic model considering the active uncoiling feed motion was validated through experimental analysis,demonstrating the motion characteristics of the continuum robot.Altogether,this study provides a framework for the design and analysis of helical-coiled continuum robots.
文摘Introduction: Reducing and maintaining viral load is crucial to reducing morbidity and mortality associated with HIV infection in children. The aim of this study was to determine the factors influencing the maintenance of children and adolescents on antiretroviral therapy in the continuum of care. Methodology: This was a descriptive and analytical cross-sectional study conducted from August 1 to August 31, 2023. It included all children living with HIV, under 15 years of age, with at least two viral load results and whose parents consented to participate in the study. Participants were recruited during their child’s treatment renewal consultations. Results: The study included 143 children, mostly boys (55.2%), with a mean age of 11.54 years (±2.8). More than half (55.2) were unaware of their HIV-positive status, and most treatments were administered by parents (60.8%). Of the 99 children with an undetectable viral load at the first test, 23 (23.2%) showed a viral rebound at the last test, mainly due to poor treatment compliance (p Conclusion: Virological rebound after suppression in children is worrying. It is crucial that the national AIDS program improves Therapeutic Education, trains health workers to communicate results and encourages ongoing dialogue with young people to reinforce adherence and maintain viral suppression.
基金supported by the National Natural Science Foundation of China(Nos.U2040201,32201334,92251304,and 42271126),the Project of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou,No.GML20220017),the Outstanding Postdoctoral Project in Jiangsu Province(No.2022ZB455),the Chinese Postdoctoral Science Foundation(No.2022M721661)and the Project of State Key Laboratory of Lake Science and Environment(No.2022SKL019).
文摘Anaerobic ammonium oxidation coupled to iron(III)reduction(Feammox)process has recently been recognized as an important pathway for removing ammonium in various natural habitats.However,our understanding for Feammox in river–estuary continuum is limited.In this study,stable isotope tracers and high-throughput amplicon sequencing were employed to determine Feammox rates and identify associated microbial communities in sediments along the Yangtze river–estuary continuum.Feammox rates averaged 0.0058±0.0069 mg N/(kg·d)and accounted for approximately 22.3%of the ammonium removed from the sediments.Sediment Fe(III),ammonium(NH_(4)^(+)),total organic carbon(TOC),and pH were identified as important factors influencing Feammox rates.Additionally,Spirochaeta,Caldilineaceae_uncultured,and Ignavibacterium were found potentially associated with Feammox,which had not been documented as Feammox-associated microbial taxa previously.This study demonstrates that Feammox plays a vital role in ammonium removal within the Yangtze river–estuary continuum,providing greater insight into nitrogen removal and cycling in aquatic ecosystems.
基金supported by the National Key R&D Program of China(No.2018YFB1305400)the Major Research Plan of the National Natural Science Foundation of China(No.92048301)+1 种基金the National Natural Science Foundation of China(No.52025054)the Joint Research Fund between the National Natural Science Foundation of China(NSFC)and Shen Zhen(No.U1713201).
文摘This paper presents a continuum manipulator inspired by the anatomical characteristics of the elephant trunk.Specifically,the manipulator mimics the conoid profile of the elephant trunk,which helps to enhance its strength.The design features two concentric parts:inner pneumatically actuated bellows and an outer tendon-driven helical spring.The tendons control the omnidirectional bending of the manipulator,while the fusion of the pneumatic bellows with the tendon-driven spring results in an antagonistic actuation mechanism that provides the manipulator with variable stiffness and extensibility.This paper presents a new design for extensible manipulator and analyzes its stiffness and motion characteristics.Experimental results are consistent with theoretical analysis,thereby demonstrating the validity of the theoretical approach and the versatile practical mechanical properties of the continuum manipulator.The impressive extensibility and variable stiffness of the manipulator were further demonstrated by performing a pin-hole assembly task.
文摘The resonance generated by different mechanisms naturally has different characteristics in sensing,and these differences increase the potential for specific detection.We designed a metasurface with both a quasi-bound state in continuum(QBIC)resonance and dipole resonance by conducting physical analyses such as electric field,current distribution,and multiple expansions on a dual-split-ring resonance with dipole resonance and a variant structure with symmetry breaking.On the other hand,the edge length of the slit was extended through a tilted split design,which further enhanced the QBIC resonance signal of the metasurface.In the sensing experiment of hyaluronic acid(HA),the limit of detection(LOD)obtained through frequency shift was 0.958 pmol∕μL,whereas the LOD obtained through the change in transmittance was 0.02 pmol∕μL.Our research findings contribute to the design of multiple resonant metasurfaces with different resonance modes,promoting further development in metasurface research and biosensing.
基金supported in part by Chunhui plan international cooperation project of China Education Ministry under grants 202201406 and HZKY20220171.
文摘Megahertz-peaked spectra(MPS)pulsars are referred as cases whose radio spectra turn over around 100 MHz.We identified 53 MPS pulsars based on the spectral data from the literature,and statistically analyzed the spatial location distribution,the magnetic field-period distribution,peak frequencies,spectral indices,and dispersion measures of these MPS pulsars.We found that there is a strong positive correlation between the dispersion measures and the peak frequencies of MPS pulsars,and negative correlations of the dispersion measures with spectral indices and the ages are also found.Such correlations suggest that the interstellar medium is an important factor that affects observational properties of MPS pulsars.
基金supported by the National Natural Science Foundation of China(No.12005198).
文摘In this study,an end-to-end deep learning method is proposed to improve the accuracy of continuum estimation in low-resolution gamma-ray spectra.A novel process for generating the theoretical continuum of a simulated spectrum is established,and a convolutional neural network consisting of 51 layers and more than 105 parameters is constructed to directly predict the entire continuum from the extracted global spectrum features.For testing,an in-house NaI-type whole-body counter is used,and 106 training spectrum samples(20%of which are reserved for testing)are generated using Monte Carlo simulations.In addition,the existing fitting,step-type,and peak erosion methods are selected for comparison.The proposed method exhibits excellent performance,as evidenced by its activity error distribution and the smallest mean activity error of 1.5%among the evaluated methods.Additionally,a validation experiment is performed using a whole-body counter to analyze a human physical phantom containing four radionuclides.The largest activity error of the proposed method is−5.1%,which is considerably smaller than those of the comparative methods,confirming the test results.The multiscale feature extraction and nonlinear relation modeling in the proposed method establish a novel approach for accurate and convenient continuum estimation in a low-resolution gamma-ray spectrum.Thus,the proposed method is promising for accurate quantitative radioactivity analysis in practical applications.
基金supported by the NSF of China(Grant No.12271334)。
文摘In the paper we derive new solutions for the discrete and continuous Schwarzian Korteweg–de Vries(SKd V)equations.These solutions are characterized by trigonometric functions as backgrounds.For the discrete SKd V equation,its solutions are derived by using trigonometric function seeds and B?cklund transformation.Solutions for the continuous SKd V equation are obtained by taking continuum limits.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.42150105,12273062 and12473095)the CAS-JSPS Joint Research Project(No.178GJHZ2023180MI)+1 种基金the National SKA Program of China(grant No.2022SKA0120101)the China Manned Space Project(No.CMS-CSST-2021-B09 and No.CMS-CSST-2021-B12)。
文摘Ionospheric scintillation behaves as the random fluctuation of amplitude and phase of the traveling electromagnetic wave caused by irregularities of the Earth ionosphere.In the radio waveband,it influences the performance of satellite navigation systems and radio astronomy observations.Here,the 3.2 m radio telescope located at Sun Yat-sen University(SYSU 3.2 m radio telescope)in Zhuhai is used to observe the radio signal from the geosynchronous Earth orbit satellite C0_(3) of the Beidou navigation system at 1561.098±3 MHz.Fluctuations of intensity in the dynamic spectra,i.e.,the standard deviation S_(4)index,are analyzed to study the scintillation of the ionosphere.The results are compared with those from global navigation satellite system(GNSS)receivers and a GPStation-6 scintillation monitor located at the same place.GNSS receiver and GPStation-6 observations confirm the scintillation events observed by the SYSU 3.2 m radio telescope.The radio telescope observations provide insights into the impact of ionospheric scintillation on astronomical observations.
基金support from the National Natural Science Foundation of China(No.12472072)the Fundamental Research Funds for the Central Universities,China.
文摘In this research,we introduce an innovative approach that combines the Continuum Damage Mechanics-Finite Element Method(CDM-FEM)with the Particle Swarm Optimization(PSO)-based technique,to predict the Medium-Low-Cycle Fatigue(MLCF)life of perforated structures.First,fatigue tests are carried out on three center-perforated structures,aiming to assess their fatigue life under various strengthening conditions.These tests reveal significant variations in fatigue life,accompanied by an examination of crack initiation through the analysis of fatigue fracture surfaces.Second,an innovative fatigue life prediction methodology is applied to perforated structures,which not only forecasts the initiation of fatigue cracks but also traces the progression of damage within these structures.It leverages an elastoplastic constitutive model integrated with damage and a damage evolution model under cyclic loads.The accuracy of this approach is validated by comparison with test results,falling within the three times error band.Finally,we explore the impact of various strengthening techniques,including cross-sectional reinforcement and cold expansion,on the fatigue life and damage evolution of these structures.This is achieved through an in-depth comparative analysis of both experimental data and computational predictions,which provides valuable insights into the behavior of perforated structures under fatigue conditions in practical applications.
文摘A previous paper showed that the real numbers between 0 and 1 could be represented by an infinite tree structure, called the ‘infinity tree’, which contains only a countably infinite number of nodes and arcs. This paper discusses how a finite-state Turing machine could, in a countably infinite number of state transitions, write all the infinite paths in the infinity tree to a countably infinite tape. Hence it is argued that the real numbers in the interval [0, 1] are countably infinite in a non-Cantorian theory of infinity based on Turing machines using countably infinite space and time. In this theory, Cantor’s Continuum Hypothesis can also be proved. And in this theory, it follows that the power set of the natural numbers P(ℕ) is countably infinite, which contradicts the claim of Cantor’s Theorem for the natural numbers. However, this paper does not claim there is an error in Cantor’s arguments that [0, 1] is uncountably infinite. Rather, this paper considers the situation as a paradox, resulting from different choices about how to represent and count the continuum of real numbers.
基金supported by the National Natural Science Foundation of China(Grant 12472113).
文摘The traditional topology optimization method of continuum structure generally uses quadrilateral elements as the basic mesh.This approach often leads to jagged boundary issues,which are traditionally addressed through post-processing,potentially altering the mechanical properties of the optimized structure.A topology optimization method of Movable Morphable Smooth Boundary(MMSB)is proposed based on the idea of mesh adaptation to solve the problem of jagged boundaries and the influence of post-processing.Based on the ICM method,the rational fraction function is introduced as the filtering function,and a topology optimization model with the minimum weight as the objective and the displacement as the constraint is established.A triangular mesh is utilized as the base mesh in this method.The mesh is re-divided in the optimization process based on the contour line,and a smooth boundary parallel to the contour line is obtained.Numerical examples demonstrate that the MMSB method effectively resolves the jagged boundary issues,leading to enhanced structural performance.
基金supported by the National Natural Science Foundation of China(Grand No.12472066).
文摘A robust generalized continuum model called the wavelength-dependent strain gradient continuum model(WDSGM)has been proposed to predict dispersion properties of two-dimensional(2D)periodic lattice metamaterials.The key idea lies in replacing the classical Taylor expansion of displacement fields with a wavelength-dependent one,naturally leading to new equations of motion and therefore a significantly improved capability of predicting dispersion characteristics.For different 2D lattices,dispersion results derived from the proposed WDSGM are verified by comparing with those obtained from the discrete model and the existing strain gradient continuum model(SGM)in the irreducible Brillouin zone.Based on the proposed model,the effects of SG orders have been investigated.Results suggest that considering the wavelength-dependent Taylor expansion and increasing the SG order are beneficial to improving the predictive performance of continuum models.The proposed model is free of any instability issue which is challenging for many existing SG methods.Under given parameters,the proposed WDSGM with eighth-order truncation is enough to predict the dispersion relation of three lattices,i.e.,the square,triangular and hexagonal lattices throughout the irreducible Brillouin zone.
