Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus o...Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus on one unique quantum phase induced by the electron-hole interaction in two-dimensional systems,known as“exciton insulators”(EIs).Although this phase of matter has been studied for more than half a century,suitable platforms for its stable realization remain scarce.We provide an overview of the strategies to realize EIs in accessible materials and structures,along with a discussion on some unique properties of EIs stemming from the band structures of these materials.Additionally,signatures in experiments to distinguish EIs are discussed.展开更多
Based on the two-dimensional （2D） system theory, an integrated predictive iterative learning control （2D-IPILC） strategy for batch processes is presented. First, the output response and the error transition model ...Based on the two-dimensional （2D） system theory, an integrated predictive iterative learning control （2D-IPILC） strategy for batch processes is presented. First, the output response and the error transition model predictions along the batch index can be calculated analytically due to the 2D Roesser model of the batch process. Then, an integrated framework of combining iterative learning control （ILC） and model predictive control （MPC） is formed reasonably. The output of feedforward ILC is estimated on the basis of the predefined process 2D model. By min- imizing a quadratic objective function, the feedback MPC is introduced to obtain better control performance for tracking problem of batch processes. Simulations on a typical batch reactor demonstrate that the satisfactory tracking performance as well as faster convergence speed can be achieved than traditional proportion type （P- t-we） ILC despite the model error and disturbances.展开更多
A new approach of generating transient chaos from two-dimensional（2D） continuous autonomous systems within finite time is presented.Based on an absolute-value switching law,the phenomenon of transient chaos takes pl...A new approach of generating transient chaos from two-dimensional（2D） continuous autonomous systems within finite time is presented.Based on an absolute-value switching law,the phenomenon of transient chaos takes place by switching between three 2D systems.Basic dynamic behavior of the systems is investigated.Numerical examples illustrate the validity of the results.展开更多
This paper is concerned with further relaxations of the stability analysis of nonlinear Roesser-type two-dimensional （2D） systems in the Takagi-Sugeno fuzzy form. To achieve the goal, a novel slack matrix variable t...This paper is concerned with further relaxations of the stability analysis of nonlinear Roesser-type two-dimensional （2D） systems in the Takagi-Sugeno fuzzy form. To achieve the goal, a novel slack matrix variable technique, which is homogenous polynomially parameter-dependent on the normalized fuzzy weighting functions with arbitrary degree, is developed and the algebraic properties of the normalized fuzzy weighting functions are collected into a set of augmented matrices. Consequently, more information about the normalized fuzzy weighting functions is involved and the relaxation quality of the stability analysis is significantly improved. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed result.展开更多
We study the stability analysis and control synthesis of uncertain discrete-time two-dimensional（2D） systems.The mathematical model of the discrete-time 2D system is established upon the well-known Roesser model,and...We study the stability analysis and control synthesis of uncertain discrete-time two-dimensional（2D） systems.The mathematical model of the discrete-time 2D system is established upon the well-known Roesser model,and the uncertainty phenomenon,which appears typically in practical environments,is modeled by a convex bounded（polytope type） uncertain domain.The stability analysis and control synthesis of uncertain discrete-time 2D systems are then developed by applying the Lyapunov stability theory.In the processes of stability analysis and control synthesis,the obtained stability/stabilzaition conditions become less conservative by applying some novel relaxed techniques.Moreover,the obtained results are formulated in the form of linear matrix inequalities,which can be easily solved via standard numerical software.Finally,numerical examples are given to demonstrate the effectiveness of the obtained results.展开更多
This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional （2D） systems. Firstly, the fuzzy modeling method for the usual one-dimensional （1D） systems is extended to t...This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional （2D） systems. Firstly, the fuzzy modeling method for the usual one-dimensional （1D） systems is extended to the 2D ease so that the underlying nonlinear 2D system can be represented by the 2D Takagi Sugeno （TS） fuzzy model, which is convenient for implementing the stability analysis. Secondly, a new kind of fuzzy Lyapunov function, which is a homogeneous polynomially parameter dependent on fuzzy membership functions, is developed to conceive less conser- vative stability conditions for the TS Roesser-type 2D system. In the process of stability analysis, the obtained stability conditions approach exactness in the sense of convergence by applying some novel relaxed techniques. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is also given to demonstrate the effectiveness of the proposed approach.展开更多
The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an over...The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an overwhelming tendency,providing powerful tools for remote health monitoring and personal health management.Among many candidates,two-dimensional(2D)materials stand out due to several exotic mechanical,electrical,optical,and chemical properties that can be efficiently integrated into atomic-thin films.While previous reviews on 2D materials for biodevices primarily focus on conventional configurations and materials like graphene,the rapid development of new 2D materials with exotic properties has opened up novel applications,particularly in smart interaction and integrated functionalities.This review aims to consolidate recent progress,highlight the unique advantages of 2D materials,and guide future research by discussing existing challenges and opportunities in applying 2D materials for smart wearable biodevices.We begin with an in-depth analysis of the advantages,sensing mechanisms,and potential applications of 2D materials in wearable biodevice fabrication.Following this,we systematically discuss state-of-the-art biodevices based on 2D materials for monitoring various physiological signals within the human body.Special attention is given to showcasing the integration of multi-functionality in 2D smart devices,mainly including self-power supply,integrated diagnosis/treatment,and human–machine interaction.Finally,the review concludes with a concise summary of existing challenges and prospective solutions concerning the utilization of2D materials for advanced biodevices.展开更多
A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface...A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface area of 427 m^(2)·g^(-1)and rich surface active sites,which help restrain polysulfides(LiPSs)through good physi-cal and chemical adsorption,while simultaneously accelerating the nucleation and dissolution kinetics of Li_(2)S,effec-tively suppressing the shuttle effect.The assembled lithium-sulfur batteries(LSBs)employing the PVS-based inter-layer delivered a high initial discharge capacity of 1386 mAh·g^(-1)at 0.1C(167.5 mAh·g^(-1)),long-term cycling stabil-ity,and good rate property.展开更多
This paper investigates ruin,capital injection,and dividends for a two-dimensional risk model.The model posits that surplus levels of insurance companies are governed by a perturbed composite Poisson risk model.This m...This paper investigates ruin,capital injection,and dividends for a two-dimensional risk model.The model posits that surplus levels of insurance companies are governed by a perturbed composite Poisson risk model.This model introduces a dependence between the two surplus levels,present in both the associated perturbations and the claims resulting from common shocks.Critical levels of capital injection and dividends are established for each of the two risks.The surplus levels are observed discretely at fixed intervals,guiding decisions on capital injection,dividends,and ruin at these junctures.This study employs a two-dimensional Fourier cosine series expansion method to approximate the finite time expected discounted operating cost until ruin.The ensuing approximation error is also quantified.The validity and accuracy of the method are corroborated through numerical examples.Furthermore,the research delves into the optimal capital allocation problem.展开更多
Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major ch...Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major challenge for their practical application.The design of battery separators has become a key aspect in addressing the challenge.MXenes,a promising two-dimensional(2D)material,offer exceptional conductivity,large surface area,high mechanical strength,and active sites for surface reactions.When assembled into layered films,MXenes form highly tunable two-dimensional channels ranging from a few angstroms to over 1 nm.These nanoconfined channels are instrumental in facilitating lithium-ion transport while effectively impeding the shuttle effect of LiPSs,which are essential for improving the specific capacity and cyclic stability of Li-S batteries.Substantial progress has been made in developing MXenes-based separators for Li-S batteries,yet there remains a research gap in summarizing advancements from the perspective of interlayer engineering.This entails maintaining the 2D nanochannels of layered MXenes-based separators while modulating the physicochemical environment within the MXenes interlayers through targeted modifications.This review highlights advancements in in situ modification of MXenes and their integration with 0D,1D,and 2D materials to construct laminated nanocomposite separators for Li-S batteries.The future development directions of MXenes-based materials in Li-S energy storage devices are also outlined,to drive further advancements in MXenes for Li-S battery separators.展开更多
Environmental catalysis has been considered one of the important research topics.Some technologies(e.g.,photocatalysis and electrocatalysis)have been intensively developed with the advance of synthetic technologies of...Environmental catalysis has been considered one of the important research topics.Some technologies(e.g.,photocatalysis and electrocatalysis)have been intensively developed with the advance of synthetic technologies of catalytical materials.In 2019,we discussed the development trend of this field,and wrote a roadmap on this topic in Chinese Chemical Letters(30(2019)2065-2088).Nowadays,we discuss it again from a new viewpoint along this road.In this paper,several subtopics are discussed,e.g.,photocatalysis based on titanium dioxide,violet phosphorus,graphitic carbon and covalent organic frameworks,electrocatalysts based on carbon,metal-and covalent-organic framework.Finally,we hope that this roadmap can enrich the development of two-dimensional materials in environmental catalysis with novel understanding,and give useful inspiration to explore new catalysts for practical applications.展开更多
The pursuit of sustainable hydrogen production has positioned water electrolysis as a cornerstone technology for global carbon neutrality.However,sluggish kinetics,catalyst scarcity,and system integration challenges h...The pursuit of sustainable hydrogen production has positioned water electrolysis as a cornerstone technology for global carbon neutrality.However,sluggish kinetics,catalyst scarcity,and system integration challenges hinder its widespread deployment.Ultrathin two-dimensional(2D)materials,with their atomically exposed surfaces,tunable electronic structures,and defect-engineering capabilities,present unique opportunities for next-generation electrocatalysts.This review provides an integrated overview of ultrathin 2D electrocatalysts,discussing their structural diversity,synthetic routes,structure-activity relationships,and mechanistic understanding in water electrolysis processes.Special focus is placed on the translation of 2D materials from laboratory research to practical device implementation,emphasizing challenges such as scalable fabrication,interfacial engineering,and operational durability in realistic electrolyzer environments.The role of advanced characterization techniques in capturing dynamic structural changes and active site evolution is discussed.Finally,we outline future research directions,emphasizing the synergy of machine learning-driven materials discovery,advanced operando characterization,and scalable system integration to accelerate the industrial translation of 2D electrocatalysts for green hydrogen production.展开更多
Hydrogen evolution reaction(HER)plays a crucial role in developing clean and renewable hydrogen energy technologies.However,conventional HER catalysts rely on expensive and scarce noble metals,which is a significant c...Hydrogen evolution reaction(HER)plays a crucial role in developing clean and renewable hydrogen energy technologies.However,conventional HER catalysts rely on expensive and scarce noble metals,which is a significant challenge for practical application.Recently,twodimensional transition metal dichalcogenides(2D-TMDs)have emerged as attractive and cost-effective alternatives for efficient electrocatalysis in the HER.Substantial efforts have been dedicated to advancing the synthesis and application of 2D-TMDs.This review highlights the design and synthesis of high-performance 2D-TMDs-based HER electrocatalysts by combining theoretical calculations with experimental methods.Subsequently,recent advances in synthesizing different types of 2D TMDs with enhanced HER activity are summarized.Finally,the conclusion and perspectives of the 2D TMDs-based HER electrocatalysts are discussed.We expect that this review will provide new insights into the design and development of highly efficient 2D TMDs-based HER electrocatalysts for industrial applications.展开更多
We propose and investigate a novel stable two-dimensional(2D)AlO_(2)with anomalous stoichiometric ratios based on first-principles calculation.2D AlO_(2)has metallic properties.It possesses the rare in-plane and out-o...We propose and investigate a novel stable two-dimensional(2D)AlO_(2)with anomalous stoichiometric ratios based on first-principles calculation.2D AlO_(2)has metallic properties.It possesses the rare in-plane and out-of-plane negative Poisson's ratio(NPR)phenomenon,originating from its special sawtooth-like structure.The absolute value of the NPR decreases as the number of layers increases.The adsorption of volatile organic compounds(VOCs)including CH_(2)O,C_(2)H_(3)Cl and C_(6)H_(6)by AlO_(2)exhibit small adsorption distance,large adsorption energy,large charge transfer and significant density of states(DOS)changes,indicating the presence of strong interactions.The desorption time of each gas molecule on the AlO_(2)surface is also evaluated,and the results further suggest that the desorption of VOCs can be controlled by changing the temperature to achieve the recycling of AlO_(2).These interesting properties make 2D AlO_(2)a promising material for electronic,mechanical and sensing applications for VOCs.展开更多
This study explores the significance of using two-dimensional shear wave elastography(2D-SWE)to assess liver stiffness(LS)and spleen area(SPA)for predicting post-hepatectomy liver failure(PHLF).By providing a non-inva...This study explores the significance of using two-dimensional shear wave elastography(2D-SWE)to assess liver stiffness(LS)and spleen area(SPA)for predicting post-hepatectomy liver failure(PHLF).By providing a non-invasive method to measure LS,which correlates with the degree of liver fibrosis,and SPA,an indicator of portal hypertension,2D-SWE offers a comprehensive evaluation of a patient’s hepatic status.These advancements are particularly crucial in hepatic surgery,where accurate preoperative assessments are essential for optimizing surgical outcomes and minimizing complications.This letter highlights the prac-tical implications of integrating 2D-SWE into clinical practice,emphasizing its potential to improve patient safety and surgical precision by enhancing the ability to predict PHLF and tailor surgical approaches accordingly.展开更多
Controlled synthesis of two-dimensional covalent organic frameworks(2D COFs),including stoichiometric and sub-stoichiometric variations,is a topic of growing interest due to its potential in gas separation application...Controlled synthesis of two-dimensional covalent organic frameworks(2D COFs),including stoichiometric and sub-stoichiometric variations,is a topic of growing interest due to its potential in gas separation applications.In this study,we successfully synthesized three distinct 2D COFs by carefully adjusting solvent compositions and monomer ratios during the synthesis of[4+4]type COFs.These included a stoichiometric[4+4]type COF and two sub-stoichiometric[4+2]type COFs,featuring unreacted amino or formyl groups.The resulting COFs exhibit different gas adsorption and separation properties.Specifically,sub-stoichiometric COF-DA with residual amino groups shows comparable adsorption capacity for C_(2)H_(2),C_(2)H_(4),and CO_(2)to stoichiometric COF-DAPy.In contrast,sub-stoichiometric COF-Py with residual formyl groups displays enhanced adsorption selectivity for C_(2)H_(2)/C_(2)H_(4)and C_(2)H_(2)/CO_(2)separation,with the C_(2)H_(2)/C_(2)H_(4)selectivity being the highest among reported COFs,attributed to increased pore polarity resulting from the presence of formyl groups.This study not only offers an additional example of substoichiometric COF synthesis but also advocates for further exploration of sub-stoichiometric COF materials,particularly in the field of gas adsorption and separation.展开更多
In recent years,as the dimensions of the conventional semiconductor technology is approaching the physical limits,while the multifunction circuits are restricted by the relatively fixed characteristics of the traditio...In recent years,as the dimensions of the conventional semiconductor technology is approaching the physical limits,while the multifunction circuits are restricted by the relatively fixed characteristics of the traditional metal−oxide−semiconductor field-effect transistors,reconfigurable devices that can realize reconfigurable characteristics and multiple functions at device level have been seen as a promising method to improve integration density and reduce power consumption.Owing to the ultrathin structure,effective control of the electronic characteristics and ability to modulate structural defects,two-dimensional(2D)materials have been widely used to fabricate reconfigurable devices.In this review,we summarize the working principles and related logic applications of reconfigurable devices based on 2D materials,including generating tunable anti-ambipolar responses and demonstrating nonvolatile operations.Furthermore,we discuss the analog signal processing applications of anti-ambipolar transistors and the artificial intelligence hardware implementations based on reconfigurable transistors and memristors,respectively,therefore highlighting the outstanding advantages of reconfigurable devices in footprint,energy consumption and performance.Finally,we discuss the challenges of the 2D materials-based reconfigurable devices.展开更多
Titanium dioxide(TiO_(2))has been an important protective ingredient in mineral-based sunscreens since the 1990s.However,traditional TiO_(2)nanoparticle formulations have seen little improvement over the past decades ...Titanium dioxide(TiO_(2))has been an important protective ingredient in mineral-based sunscreens since the 1990s.However,traditional TiO_(2)nanoparticle formulations have seen little improvement over the past decades and continue to face persistent challenges related to light transmission,biosafety,and visual appearance.Here,we report the discovery of two-dimensional(2D)TiO_(2),characterized by a micro-sized lateral dimension(~1.6μm)and atomic-scale thickness,which fundamentally resolves these long-standing issues.The 2D structure enables exceptional light management,achieving 80%visible light transparency—rendering it nearly invisible on the skin—while maintaining UV-blocking performance comparable to unmodified rutile TiO_(2)nanoparticles.Its larger lateral size results in a two-orders-of-magnitude reduction in skin penetration(0.96 w/w%),significantly enhancing biosafety.Moreover,the unique layered architecture inherently suppresses the generation of reactive oxygen species(ROS)under sunlight exposure,reducing the ROS generation rate by 50-fold compared to traditional TiO_(2)nanoparticles.Through precise metal element modulation,we further developed the first customizable sunscreen material capable of tuning UV protection ranges and automatically matching diverse skin tones.The 2D TiO_(2)offers a potentially transformative approach to modern sunscreen formulation,combining superior UV protection,enhanced safety and a natural appearance.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDs),endowed with exceptional light-matter interaction strength,have become a pivotal platform in advanced optoelectronics,enabling atomically precise control of ex...Two-dimensional(2D)transition metal dichalcogenides(TMDs),endowed with exceptional light-matter interaction strength,have become a pivotal platform in advanced optoelectronics,enabling atomically precise control of excitonic phenomena and offering transformative potential for engineering next-generation optoelectronic devices.In contrast to the narrowband absorption characteristics of conventional band-edge excitons,which are limited by the bandgap energy,highenergy excitons not only demonstrate broad momentum matching capability in the ultraviolet regime due to band nesting effects,but also exhibit distinct absorption peak signatures owing to robust excitonic stabilization under 2D confinement.These unique photophysical properties have established such systems as a prominent research frontier in contemporary exciton physics.This review primarily outlines the distinctive physical characteristics of high-energy excitons in TMDs from the perspectives of band structure,excitonic characteristics,and optical properties.Subsequently,we systematically delineate cutting-edge developments in TMD-based photonic devices exploiting high-energy excitonic band-nesting phenomena,with dedicated emphasis on the strategic engineering of nanoscale heterostructures for tailored optoelectronic functionality.Finally,the discussion concludes with an examination of the challenges associated with the design of high-energy exciton devices and their potential future applications.展开更多
Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high ef...Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high efficiency and reliability.However,the ambiguity surrounding the output flow characteristics of individual two-dimensional pumps poses a significant challenge in achieving precise closed-loop control of the EHA positions.To address this issue,this study established a comprehensive numerical model that included gap leakage to analyze the impact of leakage on the output flow characteristics of a two-dimensional piston pump.The validity of the numerical analysis was indirectly confirmed through meticulous measurements of the leakage and volumetric efficiency,ensuring robust results.The research findings indicated that,at lower pump speeds,leakage significantly affected the output flow rate,leading to potential inefficiencies in the system.Conversely,at higher rotational speeds,the impact of leakage was less pronounced,implying that the influence of leakage on the pump outlet flow must be carefully considered and managed for EHAs to perform position servo control.Additionally,the research demonstrates that two-dimensional motion does not have a unique or additional effect on pump leakage,thus simplifying the design considerations.Finally,the study concluded that maintaining an oil-filled leakage environment is beneficial because it helps reduce the impact of leakage and enhances the overall volumetric efficiency of the pump system.展开更多
基金supported by the National Key Research&Development Program of China(Grant Nos.2022YFA1403500 and 2021YFA1400500)the National Science Foundation of China(Grant Nos.62321004,12234001,and 12474215)+1 种基金supported by New Cornerstone Science Foundationa fellowship and a CRF award from the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant Nos.HKUST SRFS2324-6S01 and C7037-22GF)。
文摘Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus on one unique quantum phase induced by the electron-hole interaction in two-dimensional systems,known as“exciton insulators”(EIs).Although this phase of matter has been studied for more than half a century,suitable platforms for its stable realization remain scarce.We provide an overview of the strategies to realize EIs in accessible materials and structures,along with a discussion on some unique properties of EIs stemming from the band structures of these materials.Additionally,signatures in experiments to distinguish EIs are discussed.
基金Supported in part by the State Key Development Program for Basic Research of China(2012CB720505)the National Natural Science Foundation of China(61174105,60874049)
文摘Based on the two-dimensional （2D） system theory, an integrated predictive iterative learning control （2D-IPILC） strategy for batch processes is presented. First, the output response and the error transition model predictions along the batch index can be calculated analytically due to the 2D Roesser model of the batch process. Then, an integrated framework of combining iterative learning control （ILC） and model predictive control （MPC） is formed reasonably. The output of feedforward ILC is estimated on the basis of the predefined process 2D model. By min- imizing a quadratic objective function, the feedback MPC is introduced to obtain better control performance for tracking problem of batch processes. Simulations on a typical batch reactor demonstrate that the satisfactory tracking performance as well as faster convergence speed can be achieved than traditional proportion type （P- t-we） ILC despite the model error and disturbances.
基金Project supported by the Natural Science Foundation of Liaoning Province,China (Grant No. 201102181)
文摘A new approach of generating transient chaos from two-dimensional（2D） continuous autonomous systems within finite time is presented.Based on an absolute-value switching law,the phenomenon of transient chaos takes place by switching between three 2D systems.Basic dynamic behavior of the systems is investigated.Numerical examples illustrate the validity of the results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61203057 and 51305066)
文摘This paper is concerned with further relaxations of the stability analysis of nonlinear Roesser-type two-dimensional （2D） systems in the Takagi-Sugeno fuzzy form. To achieve the goal, a novel slack matrix variable technique, which is homogenous polynomially parameter-dependent on the normalized fuzzy weighting functions with arbitrary degree, is developed and the algebraic properties of the normalized fuzzy weighting functions are collected into a set of augmented matrices. Consequently, more information about the normalized fuzzy weighting functions is involved and the relaxation quality of the stability analysis is significantly improved. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed result.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61104010)
文摘We study the stability analysis and control synthesis of uncertain discrete-time two-dimensional（2D） systems.The mathematical model of the discrete-time 2D system is established upon the well-known Roesser model,and the uncertainty phenomenon,which appears typically in practical environments,is modeled by a convex bounded（polytope type） uncertain domain.The stability analysis and control synthesis of uncertain discrete-time 2D systems are then developed by applying the Lyapunov stability theory.In the processes of stability analysis and control synthesis,the obtained stability/stabilzaition conditions become less conservative by applying some novel relaxed techniques.Moreover,the obtained results are formulated in the form of linear matrix inequalities,which can be easily solved via standard numerical software.Finally,numerical examples are given to demonstrate the effectiveness of the obtained results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60972164,60904101,and 61273029)the Key Project of Chinese Ministry of Education(Grant No.212033)+3 种基金the Key Technologies R & D Program of Liaoning Province (Grant No.2011224006)the Program for Liaoning Innovative Research Team in University(Grant No.LT2011019)the Program for Liaoning Excellent Talents in University(Grant No.LJQ2011137)the Science and Technology Program of Shenyang (Grant No.F11-264-1-70)
文摘This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional （2D） systems. Firstly, the fuzzy modeling method for the usual one-dimensional （1D） systems is extended to the 2D ease so that the underlying nonlinear 2D system can be represented by the 2D Takagi Sugeno （TS） fuzzy model, which is convenient for implementing the stability analysis. Secondly, a new kind of fuzzy Lyapunov function, which is a homogeneous polynomially parameter dependent on fuzzy membership functions, is developed to conceive less conser- vative stability conditions for the TS Roesser-type 2D system. In the process of stability analysis, the obtained stability conditions approach exactness in the sense of convergence by applying some novel relaxed techniques. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is also given to demonstrate the effectiveness of the proposed approach.
基金the support from the National Natural Science Foundation of China(22272004,62272041)the Fundamental Research Funds for the Central Universities(YWF-22-L-1256)+1 种基金the National Key R&D Program of China(2023YFC3402600)the Beijing Institute of Technology Research Fund Program for Young Scholars(No.1870011182126)。
文摘The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an overwhelming tendency,providing powerful tools for remote health monitoring and personal health management.Among many candidates,two-dimensional(2D)materials stand out due to several exotic mechanical,electrical,optical,and chemical properties that can be efficiently integrated into atomic-thin films.While previous reviews on 2D materials for biodevices primarily focus on conventional configurations and materials like graphene,the rapid development of new 2D materials with exotic properties has opened up novel applications,particularly in smart interaction and integrated functionalities.This review aims to consolidate recent progress,highlight the unique advantages of 2D materials,and guide future research by discussing existing challenges and opportunities in applying 2D materials for smart wearable biodevices.We begin with an in-depth analysis of the advantages,sensing mechanisms,and potential applications of 2D materials in wearable biodevice fabrication.Following this,we systematically discuss state-of-the-art biodevices based on 2D materials for monitoring various physiological signals within the human body.Special attention is given to showcasing the integration of multi-functionality in 2D smart devices,mainly including self-power supply,integrated diagnosis/treatment,and human–machine interaction.Finally,the review concludes with a concise summary of existing challenges and prospective solutions concerning the utilization of2D materials for advanced biodevices.
文摘A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface area of 427 m^(2)·g^(-1)and rich surface active sites,which help restrain polysulfides(LiPSs)through good physi-cal and chemical adsorption,while simultaneously accelerating the nucleation and dissolution kinetics of Li_(2)S,effec-tively suppressing the shuttle effect.The assembled lithium-sulfur batteries(LSBs)employing the PVS-based inter-layer delivered a high initial discharge capacity of 1386 mAh·g^(-1)at 0.1C(167.5 mAh·g^(-1)),long-term cycling stabil-ity,and good rate property.
基金supported by the Shihezi University High-Level Talents Research Startup Project(Project No.RCZK202521)the National Natural Science Foundation of China(Grant Nos.12271066,11871121,12171405)+1 种基金the Chongqing Natural Science Foundation Joint Fund for Innovation and Development Project(Project No.CSTB2024NSCQLZX0085)the Chongqing Normal University Foundation(Grant No.23XLB018).
文摘This paper investigates ruin,capital injection,and dividends for a two-dimensional risk model.The model posits that surplus levels of insurance companies are governed by a perturbed composite Poisson risk model.This model introduces a dependence between the two surplus levels,present in both the associated perturbations and the claims resulting from common shocks.Critical levels of capital injection and dividends are established for each of the two risks.The surplus levels are observed discretely at fixed intervals,guiding decisions on capital injection,dividends,and ruin at these junctures.This study employs a two-dimensional Fourier cosine series expansion method to approximate the finite time expected discounted operating cost until ruin.The ensuing approximation error is also quantified.The validity and accuracy of the method are corroborated through numerical examples.Furthermore,the research delves into the optimal capital allocation problem.
基金supported by Beijing Natural Science Foundation(Nos.2232037 and 2242035)the National Natural Science Foundation of China(Nos.22005012,22105012 and 51803183)+1 种基金Chunhui Plan Cooperative Project of Ministry of Education(No.202201298)the China Postdoctoral Science Foundation Funded Project(No.2023M733520).
文摘Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major challenge for their practical application.The design of battery separators has become a key aspect in addressing the challenge.MXenes,a promising two-dimensional(2D)material,offer exceptional conductivity,large surface area,high mechanical strength,and active sites for surface reactions.When assembled into layered films,MXenes form highly tunable two-dimensional channels ranging from a few angstroms to over 1 nm.These nanoconfined channels are instrumental in facilitating lithium-ion transport while effectively impeding the shuttle effect of LiPSs,which are essential for improving the specific capacity and cyclic stability of Li-S batteries.Substantial progress has been made in developing MXenes-based separators for Li-S batteries,yet there remains a research gap in summarizing advancements from the perspective of interlayer engineering.This entails maintaining the 2D nanochannels of layered MXenes-based separators while modulating the physicochemical environment within the MXenes interlayers through targeted modifications.This review highlights advancements in in situ modification of MXenes and their integration with 0D,1D,and 2D materials to construct laminated nanocomposite separators for Li-S batteries.The future development directions of MXenes-based materials in Li-S energy storage devices are also outlined,to drive further advancements in MXenes for Li-S battery separators.
基金supported by the National Natural Science Foundation of China(Nos.52272290,21972030,52073119,and 52373210)the Natural Science Foundation of Jilin Province(No.20230101029JC)+1 种基金the Fundamental Research Program of Shanxi Province(No.202303021212159)the Monash University Malaysia–ASEAN grant(No.ASE-000010)。
文摘Environmental catalysis has been considered one of the important research topics.Some technologies(e.g.,photocatalysis and electrocatalysis)have been intensively developed with the advance of synthetic technologies of catalytical materials.In 2019,we discussed the development trend of this field,and wrote a roadmap on this topic in Chinese Chemical Letters(30(2019)2065-2088).Nowadays,we discuss it again from a new viewpoint along this road.In this paper,several subtopics are discussed,e.g.,photocatalysis based on titanium dioxide,violet phosphorus,graphitic carbon and covalent organic frameworks,electrocatalysts based on carbon,metal-and covalent-organic framework.Finally,we hope that this roadmap can enrich the development of two-dimensional materials in environmental catalysis with novel understanding,and give useful inspiration to explore new catalysts for practical applications.
文摘The pursuit of sustainable hydrogen production has positioned water electrolysis as a cornerstone technology for global carbon neutrality.However,sluggish kinetics,catalyst scarcity,and system integration challenges hinder its widespread deployment.Ultrathin two-dimensional(2D)materials,with their atomically exposed surfaces,tunable electronic structures,and defect-engineering capabilities,present unique opportunities for next-generation electrocatalysts.This review provides an integrated overview of ultrathin 2D electrocatalysts,discussing their structural diversity,synthetic routes,structure-activity relationships,and mechanistic understanding in water electrolysis processes.Special focus is placed on the translation of 2D materials from laboratory research to practical device implementation,emphasizing challenges such as scalable fabrication,interfacial engineering,and operational durability in realistic electrolyzer environments.The role of advanced characterization techniques in capturing dynamic structural changes and active site evolution is discussed.Finally,we outline future research directions,emphasizing the synergy of machine learning-driven materials discovery,advanced operando characterization,and scalable system integration to accelerate the industrial translation of 2D electrocatalysts for green hydrogen production.
基金supported by the National Key Projects for Fundamental Research and Development of China(2021YFA1500803)the National Natural Science Foundation of China(51825205,52120105002,22088102,22279150,22209186)+1 种基金the Beijing Natural Science Foundation(2222080)the Youth Innovation Promotion Association of the CAS(Y2021011)。
文摘Hydrogen evolution reaction(HER)plays a crucial role in developing clean and renewable hydrogen energy technologies.However,conventional HER catalysts rely on expensive and scarce noble metals,which is a significant challenge for practical application.Recently,twodimensional transition metal dichalcogenides(2D-TMDs)have emerged as attractive and cost-effective alternatives for efficient electrocatalysis in the HER.Substantial efforts have been dedicated to advancing the synthesis and application of 2D-TMDs.This review highlights the design and synthesis of high-performance 2D-TMDs-based HER electrocatalysts by combining theoretical calculations with experimental methods.Subsequently,recent advances in synthesizing different types of 2D TMDs with enhanced HER activity are summarized.Finally,the conclusion and perspectives of the 2D TMDs-based HER electrocatalysts are discussed.We expect that this review will provide new insights into the design and development of highly efficient 2D TMDs-based HER electrocatalysts for industrial applications.
基金financially supported by National Natural Science Foundation of China(No.22275149)Fundamental Research Funds for the Central Universities(No.SWU118105)the Next-Generation Advanced Energy Materials Program of BatteroTech Co.,Ltd.
文摘We propose and investigate a novel stable two-dimensional(2D)AlO_(2)with anomalous stoichiometric ratios based on first-principles calculation.2D AlO_(2)has metallic properties.It possesses the rare in-plane and out-of-plane negative Poisson's ratio(NPR)phenomenon,originating from its special sawtooth-like structure.The absolute value of the NPR decreases as the number of layers increases.The adsorption of volatile organic compounds(VOCs)including CH_(2)O,C_(2)H_(3)Cl and C_(6)H_(6)by AlO_(2)exhibit small adsorption distance,large adsorption energy,large charge transfer and significant density of states(DOS)changes,indicating the presence of strong interactions.The desorption time of each gas molecule on the AlO_(2)surface is also evaluated,and the results further suggest that the desorption of VOCs can be controlled by changing the temperature to achieve the recycling of AlO_(2).These interesting properties make 2D AlO_(2)a promising material for electronic,mechanical and sensing applications for VOCs.
基金Supported by Guangdong Medical Science and Technology Research Fund Project,No.A2024475.
文摘This study explores the significance of using two-dimensional shear wave elastography(2D-SWE)to assess liver stiffness(LS)and spleen area(SPA)for predicting post-hepatectomy liver failure(PHLF).By providing a non-invasive method to measure LS,which correlates with the degree of liver fibrosis,and SPA,an indicator of portal hypertension,2D-SWE offers a comprehensive evaluation of a patient’s hepatic status.These advancements are particularly crucial in hepatic surgery,where accurate preoperative assessments are essential for optimizing surgical outcomes and minimizing complications.This letter highlights the prac-tical implications of integrating 2D-SWE into clinical practice,emphasizing its potential to improve patient safety and surgical precision by enhancing the ability to predict PHLF and tailor surgical approaches accordingly.
基金supported by the National Key Research and Development Project of China(No.2022YFE0113800)the National Natural Science Foundation of China(No.22375179)+1 种基金the startup grant(No.2019125016829)in Zhejiang University of Technologypartially supported by the National Innovation and Entrepreneurship Training Program(No.202310337063)。
文摘Controlled synthesis of two-dimensional covalent organic frameworks(2D COFs),including stoichiometric and sub-stoichiometric variations,is a topic of growing interest due to its potential in gas separation applications.In this study,we successfully synthesized three distinct 2D COFs by carefully adjusting solvent compositions and monomer ratios during the synthesis of[4+4]type COFs.These included a stoichiometric[4+4]type COF and two sub-stoichiometric[4+2]type COFs,featuring unreacted amino or formyl groups.The resulting COFs exhibit different gas adsorption and separation properties.Specifically,sub-stoichiometric COF-DA with residual amino groups shows comparable adsorption capacity for C_(2)H_(2),C_(2)H_(4),and CO_(2)to stoichiometric COF-DAPy.In contrast,sub-stoichiometric COF-Py with residual formyl groups displays enhanced adsorption selectivity for C_(2)H_(2)/C_(2)H_(4)and C_(2)H_(2)/CO_(2)separation,with the C_(2)H_(2)/C_(2)H_(4)selectivity being the highest among reported COFs,attributed to increased pore polarity resulting from the presence of formyl groups.This study not only offers an additional example of substoichiometric COF synthesis but also advocates for further exploration of sub-stoichiometric COF materials,particularly in the field of gas adsorption and separation.
基金support from the National Key Research and Development Program of China(Grant nos.2024YFA1409700 and 2023YFA1407000)the National Natural Science Foundation of China(Grant no.62374158).
文摘In recent years,as the dimensions of the conventional semiconductor technology is approaching the physical limits,while the multifunction circuits are restricted by the relatively fixed characteristics of the traditional metal−oxide−semiconductor field-effect transistors,reconfigurable devices that can realize reconfigurable characteristics and multiple functions at device level have been seen as a promising method to improve integration density and reduce power consumption.Owing to the ultrathin structure,effective control of the electronic characteristics and ability to modulate structural defects,two-dimensional(2D)materials have been widely used to fabricate reconfigurable devices.In this review,we summarize the working principles and related logic applications of reconfigurable devices based on 2D materials,including generating tunable anti-ambipolar responses and demonstrating nonvolatile operations.Furthermore,we discuss the analog signal processing applications of anti-ambipolar transistors and the artificial intelligence hardware implementations based on reconfigurable transistors and memristors,respectively,therefore highlighting the outstanding advantages of reconfigurable devices in footprint,energy consumption and performance.Finally,we discuss the challenges of the 2D materials-based reconfigurable devices.
基金supported by the National Key Research and Development Project(No.2019YFA0705403)the National Natural Science Foundation of China(No.T2293693,52273311)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2020B0301030002)and the Shenzhen Basic Research Project(Nos.WDZC20200824091903001,JSGG20220831105402004,JCYJ20220818100806014)Shenzhen Major Science and Technology Projects(Nos.KCXFZ20240903094013018,KCXFZ20240903094203005)。
文摘Titanium dioxide(TiO_(2))has been an important protective ingredient in mineral-based sunscreens since the 1990s.However,traditional TiO_(2)nanoparticle formulations have seen little improvement over the past decades and continue to face persistent challenges related to light transmission,biosafety,and visual appearance.Here,we report the discovery of two-dimensional(2D)TiO_(2),characterized by a micro-sized lateral dimension(~1.6μm)and atomic-scale thickness,which fundamentally resolves these long-standing issues.The 2D structure enables exceptional light management,achieving 80%visible light transparency—rendering it nearly invisible on the skin—while maintaining UV-blocking performance comparable to unmodified rutile TiO_(2)nanoparticles.Its larger lateral size results in a two-orders-of-magnitude reduction in skin penetration(0.96 w/w%),significantly enhancing biosafety.Moreover,the unique layered architecture inherently suppresses the generation of reactive oxygen species(ROS)under sunlight exposure,reducing the ROS generation rate by 50-fold compared to traditional TiO_(2)nanoparticles.Through precise metal element modulation,we further developed the first customizable sunscreen material capable of tuning UV protection ranges and automatically matching diverse skin tones.The 2D TiO_(2)offers a potentially transformative approach to modern sunscreen formulation,combining superior UV protection,enhanced safety and a natural appearance.
基金Project supported by the National Natural Science Foundation Fund for Distinguished Young Scholars(Grant No.52025022)the National Natural Science Foundation of China(Grant Nos.62574038,12474421,62275045,and 12074060)+1 种基金the National Key R&D Program of China(Grant No.2023YFB3610200)the Fund from Jilin Province(Grant Nos.JJKH20241413KJ and 20240601049RC)。
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDs),endowed with exceptional light-matter interaction strength,have become a pivotal platform in advanced optoelectronics,enabling atomically precise control of excitonic phenomena and offering transformative potential for engineering next-generation optoelectronic devices.In contrast to the narrowband absorption characteristics of conventional band-edge excitons,which are limited by the bandgap energy,highenergy excitons not only demonstrate broad momentum matching capability in the ultraviolet regime due to band nesting effects,but also exhibit distinct absorption peak signatures owing to robust excitonic stabilization under 2D confinement.These unique photophysical properties have established such systems as a prominent research frontier in contemporary exciton physics.This review primarily outlines the distinctive physical characteristics of high-energy excitons in TMDs from the perspectives of band structure,excitonic characteristics,and optical properties.Subsequently,we systematically delineate cutting-edge developments in TMD-based photonic devices exploiting high-energy excitonic band-nesting phenomena,with dedicated emphasis on the strategic engineering of nanoscale heterostructures for tailored optoelectronic functionality.Finally,the discussion concludes with an examination of the challenges associated with the design of high-energy exciton devices and their potential future applications.
基金Supported by National Natural Science Foundation of China(Grant No.52205072).
文摘Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high efficiency and reliability.However,the ambiguity surrounding the output flow characteristics of individual two-dimensional pumps poses a significant challenge in achieving precise closed-loop control of the EHA positions.To address this issue,this study established a comprehensive numerical model that included gap leakage to analyze the impact of leakage on the output flow characteristics of a two-dimensional piston pump.The validity of the numerical analysis was indirectly confirmed through meticulous measurements of the leakage and volumetric efficiency,ensuring robust results.The research findings indicated that,at lower pump speeds,leakage significantly affected the output flow rate,leading to potential inefficiencies in the system.Conversely,at higher rotational speeds,the impact of leakage was less pronounced,implying that the influence of leakage on the pump outlet flow must be carefully considered and managed for EHAs to perform position servo control.Additionally,the research demonstrates that two-dimensional motion does not have a unique or additional effect on pump leakage,thus simplifying the design considerations.Finally,the study concluded that maintaining an oil-filled leakage environment is beneficial because it helps reduce the impact of leakage and enhances the overall volumetric efficiency of the pump system.
