Journal Customer services For ordering information,claims and any enquiry concerning your journal subscription please go to contact your nearest office.America:Tel:(401)515-4764 Europe,Middle East,Africa and Asia Paci...Journal Customer services For ordering information,claims and any enquiry concerning your journal subscription please go to contact your nearest office.America:Tel:(401)515-4764 Europe,Middle East,Africa and Asia Pacific:Email:asiaar@163.com;523404392@qq.com;434421224@qq.com Tel:+86-551-65148112 Annual subscription rate(12 issues):US$300.展开更多
This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematic...This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematical models of the tooth flanks for the face gear drives are established based on the gear skiving processes.Then,load tooth contact analysis(LTCA)model is established to calculate the contact performance data.Next,a two-stage optimization model is employed to determine the optimal parameters of the cutting edge with improved contact performances.The effectiveness of this method is validated through simulations and rolling tests.Compared with the traditional method,the proposed method can machine both the face gear and its mating pinion with a single cutter.Simulation results show that the proposed method avoids tooth surface edge contact,with the maximum tooth surface contact stress reduced by 31.7%,the contact ratio decreases by 21.5%,and the transmission error increases by 22.3%.Rolling tests verify the consistency of tooth surface contact patterns between simulations and experiments.The proposed method provides a reference for the cutting edge design of skiving cutters for face gear pairs.展开更多
MXene-based smart contact lenses demonstrate a cutting-edge advancement in wearable ophthalmic technology,combining real-time biosensing,therapeutic capabilities,and user comfort in a single platform.These devices tak...MXene-based smart contact lenses demonstrate a cutting-edge advancement in wearable ophthalmic technology,combining real-time biosensing,therapeutic capabilities,and user comfort in a single platform.These devices take the advantage of the exceptional electrical conductivity,mechanical flexibility,and biocompatibility of two-dimensional MXenes to enable noninvasive,tear-based monitoring of key physiological markers such as intraocular pressure and glucose levels.Recent developments focus on the integration of transparent MXene films into the conventional lens materials,allowing multifunctional performance including photothermal therapy,antimicrobial and anti-inflammation protection,and dehydration resistance.These innovations offer promising strategies for ocular disease management and eye protection.In addition to their multifunctionality,improvements in MXene synthesis and device engineering have enhanced the stability,transparency,and wearability of these lenses.Despite these advances,challenges remain in long-term biostability,scalable production,and integration with wireless communication systems.This review summarizes the current progress,key challenges,and future directions of MXene-based smart contact lenses,highlighting their transformative potential in next-generation digital healthcare and ophthalmic care.展开更多
The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfa...The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.展开更多
In this paper,our main goal is to study a new mathematical model which describes the frictional contact between a foundation and a deformable body which is composed of viscoplastic materials and where the process is c...In this paper,our main goal is to study a new mathematical model which describes the frictional contact between a foundation and a deformable body which is composed of viscoplastic materials and where the process is considered dynamic.The contact condition on the normal plane is modeled by a unilateral constraint condition for a version of normal velocity in which the memory effect and the adhesion are considered.On the tangential plane a frictional contact condition is governed by the Clarke subdifferential of a locally Lipschitz function,and the evolution of the bonding field is governed by an ordinary differential equation.We formulate this problem as coupled system that consists of two ordinary differential equations and a variational-hemivariational inequality.Then,the existence,uniqueness and continuous dependence of the solution on the data results concerning the abstract system are established.Finally,we use the abstract results to show the existence and uniqueness of the solution to the contact problem.展开更多
Objective: To develop an evidence-based plan for cleaning operating room and evaluate the impact on high-frequency contact surfaces. Method: The evidence application model of the JBI Evidence-Based Nursing Center was ...Objective: To develop an evidence-based plan for cleaning operating room and evaluate the impact on high-frequency contact surfaces. Method: The evidence application model of the JBI Evidence-Based Nursing Center was utilized to create a strategy, which was implemented in a tertiary-level hospital in Yunnan Province. The adenosine triphosphate (ATP) biological biofluorescence detection method was used to assess the quality of cleaning before and after the intervention. Results: A total of 17 quality review indicators were established in this study. Following the application of evidence, the implementation rate for 16 quality review indicators increased significantly, from a range of 0-65.8% to 81.5-100%. Moreover, the pass rate of ATP bioluminescence detection on high-frequency contact surfaces increased from 14.07% to 47.19%, with significant difference (p < 0.05). Conclusion: The evidence-based environmental cleaning program proved to enhance the overall cleanliness of operating room and reduce the risk of surgical infections. This strategy holds promise for effective cleaning of operating room.展开更多
This paper quantitatively discusses the influence of well contact on single-event transient(SET)in sub-20 nm FinFET by two-photon absorption(TPA)pulse laser.Two groups of inverter chains were designed to investigate t...This paper quantitatively discusses the influence of well contact on single-event transient(SET)in sub-20 nm FinFET by two-photon absorption(TPA)pulse laser.Two groups of inverter chains were designed to investigate the impact of well contact distance on the FinFET process.The experimental results show that the SET pulse width has a bimodal symmetric distribution,which is different from that of a bulk planar CMOS device.To investigate the detailed mechanism of the phenomenon,a high-precision FinFET TCAD model was established,in which both Id-Vd and Id-Vg errors were less than 10%compared to the SPICE model provided by the commercial process.TCAD simulation under heavy ion injection showed the mechanism of the abnormal phenomenon,where the well contact plays a major role in charge collection at the near-well contact distance,while the source plays a major role at the far distance.This phenomenon is completely different from that of planar CMOS devices.This indicates that the SET mechanism becomes more complicated during the FinFET process.Therefore,more effective SET hardening methods should be investigated for FinFET.展开更多
Piezoelectric semiconductor(PSC)materials exhibit strong electromechanical coupling affected by free carriers,which makes their contact behavior essential for sensors,actuators,and electronic devices.Analytical models...Piezoelectric semiconductor(PSC)materials exhibit strong electromechanical coupling affected by free carriers,which makes their contact behavior essential for sensors,actuators,and electronic devices.Analytical models for three-dimensional(3D)PSC contact problems are still scarce,especially for conductive indenters.This work develops a semi-analytical framework to study the 3D frictionless contact between a conductive indenter and a PSC half-space.Fundamental solutions under a unit force and a unit electric charge are derived,and the corresponding frequency response functions are combined with a discrete convolution-fast Fourier transform(DC-FFT)algorithm to achieve an efficient semi-analytical contact model.The numerical results demonstrate that an increase in the surface charge density reduces the indentation pressure and modifies the electric potential distribution.A higher steady carrier concentration enhances the screening effect,suppresses the electromechanical coupling,and shifts the system response toward purely elastic behaviors.The sensitivity analysis shows that the indentation depth is dominated by the elastic constants,while the electric potential is mainly affected by the piezoelectric coefficient.Although the analysis is carried out with spherical indenters,the model is not limited to a specific indenter shape.It provides an effective tool for investigating complex 3D PSC contact problems and offers useful insights into the design of PSC materials-based devices.展开更多
In rock engineering,natural cracks in rock masses subjected to external loads tend to initiate and propagate,leading to potential safety hazards.To investigate the effect of cracking behavior on the mechanical propert...In rock engineering,natural cracks in rock masses subjected to external loads tend to initiate and propagate,leading to potential safety hazards.To investigate the effect of cracking behavior on the mechanical properties of rocks,the cracking processes of pre-cracked rocks have been extensively studied using numerical modeling methods.The peridynamics(PD)exhibits advantages over other numerical methods due to the absence of the requirements for remeshing and external crack growth criterion.However,for modeling pre-cracked rock cracking processes under impact,current PD implementations lack generally applicable rock constitutive models and impact contact models,which leads to difficulties in determining rock material parameters and efficiently calculating impact loads.This paper proposes a non-ordinary state-based peridynamics(NOSBPD)modeling method integrating the Drucker-Prager(DP)plasticity model and an efficient contact model to address the above problems.In the proposed method,the Drucker-Prager plasticity model is integrated into the NOSBPD,thereby equipping NOSBPD with the capability to accurately characterize the nonlinear stress-strain relationship inherent in rocks.An efficient contact model between particles and meshes is designed to calculate the impact loads,which is essentially a coupling method of PD with the finite element method(FEM).The effectiveness of the proposed NOSBPD modeling method is verified by comparison with other numerical methods and experiments.Experimental results indicate that the proposed method can effectively and accurately predict the 3D cracking processes of pre-cracked cracks under impact loading,and the maximum principal stress is the key driver behind wing crack formation in pre-cracked rocks.展开更多
In-space cable-driven manipulators exhibit several advantages,such as a large range of motion,high dexterity,and lightweight structure.However,kinematic and dynamic analysis play an essential role in designing a cable...In-space cable-driven manipulators exhibit several advantages,such as a large range of motion,high dexterity,and lightweight structure.However,kinematic and dynamic analysis play an essential role in designing a cable-driven manipulator.In this paper,the kinematic analysis of a type of cable-driven manipulator is performed,and a motion planning scheme is conducted to actuate this manipulator.Moreover,a flexible multi-body dynamic model of a cable-driven manipulator considering the frictional contact between the cables and pulleys is established.To describe properties such as flexibility,vibration,and variable length of the cable,this paper utilizes reducedorder beam elements of the Absolute Nodal Coordinates Formulation(ANCF)in Arbitrary Lagrangian Eulerian(ALE)framework.Additionally,a virtual element is introduced to model the contact segment in the cable-pulley system.A tension decay factor is employed to account for the friction in the contact segment.To validate the proposed method,a semi-analytical model based on D'Alembert's principle is established.Cross-verification is performed to validate the accuracy of both models.The model is further applied to simulate the rotation of the cable-driven manipulator with different structural parameters and frictional factors.The results from the analyses provide valuable guidance for the design and motion control of the in-space cable-driven manipulator.Finally,a prototype of a single module is manufactured and tested.Ground experiments are carried out to verify the kinematic and dynamic models.展开更多
Droplet impact on solid surfaces plays a critical role in a wide range of applications,including inkjet printing,spray cooling,surface coatings,and microdroplet chemistry.Precise control of droplet–surface interactio...Droplet impact on solid surfaces plays a critical role in a wide range of applications,including inkjet printing,spray cooling,surface coatings,and microdroplet chemistry.Precise control of droplet–surface interactions is essential,but the fundamental mechanisms governing this process are still not fully understood.In this study,we demonstrate that large contact angle hysteresis(CAH)on hydrophobic nanoporous surfaces significantly amplifies post-impact droplet oscillations.This reveals the critical influence of CAH on the redistribution of impact energy and the modulation of droplet–surface interactions.Using shape mode decomposition via Legendre polynomials and fast Fourier transform spectral analysis,we show that surfaces with larger CAH excite and sustain higher-order droplet shape mode oscillations,leading to persistent capillary waves even after contact line pinning.The observed amplitude modulation and multiple frequency components within individual shape modes reveal nonlinear energy transfer between different modes.These amplified and coupled oscillations are shown to promote daughter droplet coalescence.This study presents a framework for understanding the role of CAH in storing and redistributing impact energy through nonlinear mode excitation and establishes CAH as a critical design parameter for controlling fluid dynamics on solid surfaces.展开更多
This study explores the dynamic contact response of a viscoelastic functionally graded material(FGM)-coated half-plane under a rigid flat punch subjected to a time-harmonic vertical force.The elastic modulus and mass ...This study explores the dynamic contact response of a viscoelastic functionally graded material(FGM)-coated half-plane under a rigid flat punch subjected to a time-harmonic vertical force.The elastic modulus and mass density of the FGM coating vary exponentially along the thickness direction.The FGM coating and the homogeneous half-plane possess viscoelastic properties,which are described by a linearly hysteretic damping model.By applying the asymptotic method and the Fourier integral transform technique,the contact problem is converted into a Cauchy singular integral equation.The effects of excitation frequency,gradient index,damping factor ratio,and punch width on the vertical impedance and dynamic contact stress are analyzed.The results indicate that adjusting the gradient index of the FGM coating can significantly affect the contact stress and vertical impedance.展开更多
The reliable operation of lithium-ion batteries(LIBs)in low temperatures has long been hindered by severe side reactions on graphite anodes.To develop a commercially viable low-temperature electrolyte,we design a solv...The reliable operation of lithium-ion batteries(LIBs)in low temperatures has long been hindered by severe side reactions on graphite anodes.To develop a commercially viable low-temperature electrolyte,we design a solvent-resistant Nitrate-coordinated electrolyte.The practical Ah-level graphite LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) pouch cell with the newly developed electrolyte demonstrates a significant breakthrough in cycling stability,exhibiting negligible capacity fade after 250 cycles at-30℃ and 0.1 C.NO_(3)^(-),as the functional additive,compresses the electric field around Li^(+)through electrostatic interactions,mimicking the Debye-screening effect and inducing the coordinative exclusion of free ethyl acetate molecules at low temperatures.The transformation from contact ion pairs(CIPs)formed by Pto solventseparated ion pairs is significantly restrained,which mitigates the continuous reactions between the electrolyte and inevitable lithium deposition at low temperature.Additionally,this customized inert CIPs form a solid electrolyte interphase on graphite that exhibits remarkable ionic conductivity and rigidity,preventing excessive Li dendrite growth.This finding offers new insights into the relationship of microstructure-performance for low-temperature electrolytes,demonstrating that relying solely on inert CIPs can also inhibit the decomposition of the interfacial electrolyte,and inspires a unique design concept for high-performance,commercially viable LIBs that operate reliably in sub-zero environments.展开更多
The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation...The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation supported by experimental evidence remains lacking. This work investigates the effects of fluorine incorporation and electrothermal annealing(ETA) on the current transport process at Ni/β-Ga_(2)O_(3) Schottky contacts. X-ray photoelectron spectroscopy and first-principles calculations confirm the presence of fluorine substitutions for oxygen and oxygen vacancies and their lowering effect on the Schottky barrier heights. Additionally, accurate electrothermal hybrid TCAD simulations validates the extremely short-duration high temperatures(683 K) induced by ETA, which facilitates lattice rearrangement and reduces interface trap states. The interface trap states are quantitatively resolved through frequency-dependent conductance technique, showing the trap density(DT)reduction from(0.88-2.48) × 10^(11) cm^(-2)·eV^(-1) to(0.46-2.09) × 10^(11) cm^(-2)·eV^(-1). This investigation offers critical insights into the β-Ga_(2)O_(3) contacts with the collaborative treatment and solids the promotion of high-performance β-Ga_(2)O_(3) power devices.展开更多
In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypro...In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.展开更多
The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the in...The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.展开更多
Magnesium and its alloys have gained relevance for their light-weight combined with a high value of strength-to-weight ratio,which makes them useful in fields such as aerospace,automotive as well as biomedical enginee...Magnesium and its alloys have gained relevance for their light-weight combined with a high value of strength-to-weight ratio,which makes them useful in fields such as aerospace,automotive as well as biomedical engineering.Unfortunately,the poor corrosion resistance of Mg-alloys limits their wide acceptance.Advanced composite coatings which are self-healing,superhydrophobic anti corrosive,and wear resistant are new synthetic materials for abating these challenges.The superimposed superhydrophobic surfaces help in minimizing their water contact,thus slowing down the electrochemical reactions on the surface of the alloys,while their self-healing characteristics autonomously aid in the repair of any induced micro-crack,defect or damage towards ensuring the metal's long-term protection.In addition,the integration of wear-resistant materials further improves the durability of coatings under mechanical stress.The most recent research efforts have been directed towards the preparation of multifunctional composites,with an emphasis on nanomaterials,functional polymers,and state-of-the-art fabrication techniques in order to take advantage of their synergistic effects.Some of the methods that have so far exhibited promising potentials in fabricating these materials include the sol-gel method,layer-by-layer assembly,and plasma treatments.However,most of the fabricated products are still faced with significant challenges ranging from long-term stability to homogeneous adhesion of the coatings and their scalability for industrial applications.This review discusses the recent progress and the relationship between corrosion inhibition and self-healing efficiencies of wear resistant polymer nanocomposite coatings.Some challenges related to optimizing coating performance were also discussed.In addition,future directions ranging from the consideration of bioinspired designs,novel hybrid nanocomposite materials,and environmentally sustainable solutions integrated with smart protective coatings were also proposed as new wave technologies that can potentially revolutionize the corrosion protection offered by Mg alloys while opening up prospects for improved performance and sustainability.展开更多
The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this pape...The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this paper constructs a transient rolling contact finite element model of the wheel-rail in switch under different ramps using ANSYS/LSDYNA method,and analyzes the tribology and damage characteristics when the wheel passes through the switch at a uniform speed.Our research findings reveal that the vibration induced in the switch rail during the wheel load transfer process leads to a step-like increase in the contact force.Moreover,the interaction between the wheel and the rail primarily involves slip contact,which may significantly contribute to the formation of corrugations on the switch rail.Additionally,the presence of large ramps exacerbates switch rail wear and rolling contact fatigue,resulting in a notable 13.2%increase in switch rail damage under 40‰ramp conditions compared to flat(0‰ramp)conditions.Furthermore,the large ramps can alter the direction of crack propagation,ultimately causing surface spalling of the rail.Therefore,large ramps intensify the dynamic interactions during the wheel load transfer process,further aggravating the crack and spalling damage to the switch rails.展开更多
The models constructed by particle flow simulation method can effectively simulate the heterogeneous substance characteristics and failure behaviors of rocks.However,existing contact models overlook the rock cracks,an...The models constructed by particle flow simulation method can effectively simulate the heterogeneous substance characteristics and failure behaviors of rocks.However,existing contact models overlook the rock cracks,and the various simulation methods that do consider cracks still exhibit certain limitations.In this paper,based on Flat-Joint model and Linear Parallel Bond model,a crack contact model considering linked substance in the crack is proposed by splitting the crack contact into two portions:linked portion and unlinked portion for calculation.The new contact model considers the influence of crack closure on the contact force-displacement law.And a better compressive tensile strength ratio(UCS/T)was obtained by limiting the failure of the contact bond to be solely controlled by the contact force and moment of the linked portion.Then,by employing the FISH Model tool within the Particle Flow Code,the contact model was constructed and verified through contact force–displacement experiments and loading-unloading tests with cracked model.Finally,the contact model was tested through simulations of rock mechanics experiments.The results indicate that the contact model can effectively simulate the axial and lateral strain laws of rocks simultaneously and has a relatively good reproduction of the bi-modularity of rocks.展开更多
文摘Journal Customer services For ordering information,claims and any enquiry concerning your journal subscription please go to contact your nearest office.America:Tel:(401)515-4764 Europe,Middle East,Africa and Asia Pacific:Email:asiaar@163.com;523404392@qq.com;434421224@qq.com Tel:+86-551-65148112 Annual subscription rate(12 issues):US$300.
基金Project(2024YFB3410402)supported by the National Key R&D Program of ChinaProject(52075558)supported by the National Natural Science Foundation of China+2 种基金Project(2021RC3012)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(2023CXQD050)supported by the Central South University Innovation-Driven Research Program,ChinaProject(CX20230255)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematical models of the tooth flanks for the face gear drives are established based on the gear skiving processes.Then,load tooth contact analysis(LTCA)model is established to calculate the contact performance data.Next,a two-stage optimization model is employed to determine the optimal parameters of the cutting edge with improved contact performances.The effectiveness of this method is validated through simulations and rolling tests.Compared with the traditional method,the proposed method can machine both the face gear and its mating pinion with a single cutter.Simulation results show that the proposed method avoids tooth surface edge contact,with the maximum tooth surface contact stress reduced by 31.7%,the contact ratio decreases by 21.5%,and the transmission error increases by 22.3%.Rolling tests verify the consistency of tooth surface contact patterns between simulations and experiments.The proposed method provides a reference for the cutting edge design of skiving cutters for face gear pairs.
文摘MXene-based smart contact lenses demonstrate a cutting-edge advancement in wearable ophthalmic technology,combining real-time biosensing,therapeutic capabilities,and user comfort in a single platform.These devices take the advantage of the exceptional electrical conductivity,mechanical flexibility,and biocompatibility of two-dimensional MXenes to enable noninvasive,tear-based monitoring of key physiological markers such as intraocular pressure and glucose levels.Recent developments focus on the integration of transparent MXene films into the conventional lens materials,allowing multifunctional performance including photothermal therapy,antimicrobial and anti-inflammation protection,and dehydration resistance.These innovations offer promising strategies for ocular disease management and eye protection.In addition to their multifunctionality,improvements in MXene synthesis and device engineering have enhanced the stability,transparency,and wearability of these lenses.Despite these advances,challenges remain in long-term biostability,scalable production,and integration with wireless communication systems.This review summarizes the current progress,key challenges,and future directions of MXene-based smart contact lenses,highlighting their transformative potential in next-generation digital healthcare and ophthalmic care.
基金National Natural Science Foundation of China(Grant No.52278121).
文摘The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.
基金supported by the NSF of Shanxi(202303021221168)the Industry-university-research project of Shanxi Datong University(2022CXY10,2022CXY13).
文摘In this paper,our main goal is to study a new mathematical model which describes the frictional contact between a foundation and a deformable body which is composed of viscoplastic materials and where the process is considered dynamic.The contact condition on the normal plane is modeled by a unilateral constraint condition for a version of normal velocity in which the memory effect and the adhesion are considered.On the tangential plane a frictional contact condition is governed by the Clarke subdifferential of a locally Lipschitz function,and the evolution of the bonding field is governed by an ordinary differential equation.We formulate this problem as coupled system that consists of two ordinary differential equations and a variational-hemivariational inequality.Then,the existence,uniqueness and continuous dependence of the solution on the data results concerning the abstract system are established.Finally,we use the abstract results to show the existence and uniqueness of the solution to the contact problem.
文摘Objective: To develop an evidence-based plan for cleaning operating room and evaluate the impact on high-frequency contact surfaces. Method: The evidence application model of the JBI Evidence-Based Nursing Center was utilized to create a strategy, which was implemented in a tertiary-level hospital in Yunnan Province. The adenosine triphosphate (ATP) biological biofluorescence detection method was used to assess the quality of cleaning before and after the intervention. Results: A total of 17 quality review indicators were established in this study. Following the application of evidence, the implementation rate for 16 quality review indicators increased significantly, from a range of 0-65.8% to 81.5-100%. Moreover, the pass rate of ATP bioluminescence detection on high-frequency contact surfaces increased from 14.07% to 47.19%, with significant difference (p < 0.05). Conclusion: The evidence-based environmental cleaning program proved to enhance the overall cleanliness of operating room and reduce the risk of surgical infections. This strategy holds promise for effective cleaning of operating room.
基金supported by Natural Science Foundation of China(Nos.62174180 and 62304258)National Key R&D Program of China(No.2023YFA1609000)。
文摘This paper quantitatively discusses the influence of well contact on single-event transient(SET)in sub-20 nm FinFET by two-photon absorption(TPA)pulse laser.Two groups of inverter chains were designed to investigate the impact of well contact distance on the FinFET process.The experimental results show that the SET pulse width has a bimodal symmetric distribution,which is different from that of a bulk planar CMOS device.To investigate the detailed mechanism of the phenomenon,a high-precision FinFET TCAD model was established,in which both Id-Vd and Id-Vg errors were less than 10%compared to the SPICE model provided by the commercial process.TCAD simulation under heavy ion injection showed the mechanism of the abnormal phenomenon,where the well contact plays a major role in charge collection at the near-well contact distance,while the source plays a major role at the far distance.This phenomenon is completely different from that of planar CMOS devices.This indicates that the SET mechanism becomes more complicated during the FinFET process.Therefore,more effective SET hardening methods should be investigated for FinFET.
基金Project supported by the National Natural Science Foundation of China(No.12402113)the Sichuan Science and Technology Program(No.2024NSFSC0037)。
文摘Piezoelectric semiconductor(PSC)materials exhibit strong electromechanical coupling affected by free carriers,which makes their contact behavior essential for sensors,actuators,and electronic devices.Analytical models for three-dimensional(3D)PSC contact problems are still scarce,especially for conductive indenters.This work develops a semi-analytical framework to study the 3D frictionless contact between a conductive indenter and a PSC half-space.Fundamental solutions under a unit force and a unit electric charge are derived,and the corresponding frequency response functions are combined with a discrete convolution-fast Fourier transform(DC-FFT)algorithm to achieve an efficient semi-analytical contact model.The numerical results demonstrate that an increase in the surface charge density reduces the indentation pressure and modifies the electric potential distribution.A higher steady carrier concentration enhances the screening effect,suppresses the electromechanical coupling,and shifts the system response toward purely elastic behaviors.The sensitivity analysis shows that the indentation depth is dominated by the elastic constants,while the electric potential is mainly affected by the piezoelectric coefficient.Although the analysis is carried out with spherical indenters,the model is not limited to a specific indenter shape.It provides an effective tool for investigating complex 3D PSC contact problems and offers useful insights into the design of PSC materials-based devices.
基金support from the National Natural Science Foundation of China(Grant Nos.42277161 and 42230709).
文摘In rock engineering,natural cracks in rock masses subjected to external loads tend to initiate and propagate,leading to potential safety hazards.To investigate the effect of cracking behavior on the mechanical properties of rocks,the cracking processes of pre-cracked rocks have been extensively studied using numerical modeling methods.The peridynamics(PD)exhibits advantages over other numerical methods due to the absence of the requirements for remeshing and external crack growth criterion.However,for modeling pre-cracked rock cracking processes under impact,current PD implementations lack generally applicable rock constitutive models and impact contact models,which leads to difficulties in determining rock material parameters and efficiently calculating impact loads.This paper proposes a non-ordinary state-based peridynamics(NOSBPD)modeling method integrating the Drucker-Prager(DP)plasticity model and an efficient contact model to address the above problems.In the proposed method,the Drucker-Prager plasticity model is integrated into the NOSBPD,thereby equipping NOSBPD with the capability to accurately characterize the nonlinear stress-strain relationship inherent in rocks.An efficient contact model between particles and meshes is designed to calculate the impact loads,which is essentially a coupling method of PD with the finite element method(FEM).The effectiveness of the proposed NOSBPD modeling method is verified by comparison with other numerical methods and experiments.Experimental results indicate that the proposed method can effectively and accurately predict the 3D cracking processes of pre-cracked cracks under impact loading,and the maximum principal stress is the key driver behind wing crack formation in pre-cracked rocks.
基金co-supported by the National Natural Science Foundation of China(Nos.12102034 and 12125201)the Open Fund of State Key Laboratory of Robotics and Systems(HIT),China。
文摘In-space cable-driven manipulators exhibit several advantages,such as a large range of motion,high dexterity,and lightweight structure.However,kinematic and dynamic analysis play an essential role in designing a cable-driven manipulator.In this paper,the kinematic analysis of a type of cable-driven manipulator is performed,and a motion planning scheme is conducted to actuate this manipulator.Moreover,a flexible multi-body dynamic model of a cable-driven manipulator considering the frictional contact between the cables and pulleys is established.To describe properties such as flexibility,vibration,and variable length of the cable,this paper utilizes reducedorder beam elements of the Absolute Nodal Coordinates Formulation(ANCF)in Arbitrary Lagrangian Eulerian(ALE)framework.Additionally,a virtual element is introduced to model the contact segment in the cable-pulley system.A tension decay factor is employed to account for the friction in the contact segment.To validate the proposed method,a semi-analytical model based on D'Alembert's principle is established.Cross-verification is performed to validate the accuracy of both models.The model is further applied to simulate the rotation of the cable-driven manipulator with different structural parameters and frictional factors.The results from the analyses provide valuable guidance for the design and motion control of the in-space cable-driven manipulator.Finally,a prototype of a single module is manufactured and tested.Ground experiments are carried out to verify the kinematic and dynamic models.
基金supported by the German Federal Ministry of Education and Research(BMBF)within the project H2Giga-SINEWAVE OxySep,grant no 03HY123Eand the Faculty of Mechanical Science and Engineering at TU Dresden.Pengfei Zhao would like to acknowledge the China Scholarship Council(CSC)+3 种基金supported by a Humboldt Research Fellowship from the Alexander von Humboldt Foundationthe financial support from Qinghai Province(No.2025ZY001,2024000060)Chinese Academy of Sciences(No.2023000024)funding from the Deutsche Forschungsgemeinschaft:Project ID 265191195-SFB1194 and 456180046.
文摘Droplet impact on solid surfaces plays a critical role in a wide range of applications,including inkjet printing,spray cooling,surface coatings,and microdroplet chemistry.Precise control of droplet–surface interactions is essential,but the fundamental mechanisms governing this process are still not fully understood.In this study,we demonstrate that large contact angle hysteresis(CAH)on hydrophobic nanoporous surfaces significantly amplifies post-impact droplet oscillations.This reveals the critical influence of CAH on the redistribution of impact energy and the modulation of droplet–surface interactions.Using shape mode decomposition via Legendre polynomials and fast Fourier transform spectral analysis,we show that surfaces with larger CAH excite and sustain higher-order droplet shape mode oscillations,leading to persistent capillary waves even after contact line pinning.The observed amplitude modulation and multiple frequency components within individual shape modes reveal nonlinear energy transfer between different modes.These amplified and coupled oscillations are shown to promote daughter droplet coalescence.This study presents a framework for understanding the role of CAH in storing and redistributing impact energy through nonlinear mode excitation and establishes CAH as a critical design parameter for controlling fluid dynamics on solid surfaces.
基金Project supported by the National Natural Science Foundation of China(Nos.12021002,12192212,and 12462007)。
文摘This study explores the dynamic contact response of a viscoelastic functionally graded material(FGM)-coated half-plane under a rigid flat punch subjected to a time-harmonic vertical force.The elastic modulus and mass density of the FGM coating vary exponentially along the thickness direction.The FGM coating and the homogeneous half-plane possess viscoelastic properties,which are described by a linearly hysteretic damping model.By applying the asymptotic method and the Fourier integral transform technique,the contact problem is converted into a Cauchy singular integral equation.The effects of excitation frequency,gradient index,damping factor ratio,and punch width on the vertical impedance and dynamic contact stress are analyzed.The results indicate that adjusting the gradient index of the FGM coating can significantly affect the contact stress and vertical impedance.
基金support from the Heilongjiang Touyan Innovation Team Program(HITTY-20190033)National Natural Science Foundation of China(22278096)Innovation Special Project on Science and Technology for Carbon Peaking and Carbon Neutrality in Jiangsu Province(WSSJH20230015)。
文摘The reliable operation of lithium-ion batteries(LIBs)in low temperatures has long been hindered by severe side reactions on graphite anodes.To develop a commercially viable low-temperature electrolyte,we design a solvent-resistant Nitrate-coordinated electrolyte.The practical Ah-level graphite LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) pouch cell with the newly developed electrolyte demonstrates a significant breakthrough in cycling stability,exhibiting negligible capacity fade after 250 cycles at-30℃ and 0.1 C.NO_(3)^(-),as the functional additive,compresses the electric field around Li^(+)through electrostatic interactions,mimicking the Debye-screening effect and inducing the coordinative exclusion of free ethyl acetate molecules at low temperatures.The transformation from contact ion pairs(CIPs)formed by Pto solventseparated ion pairs is significantly restrained,which mitigates the continuous reactions between the electrolyte and inevitable lithium deposition at low temperature.Additionally,this customized inert CIPs form a solid electrolyte interphase on graphite that exhibits remarkable ionic conductivity and rigidity,preventing excessive Li dendrite growth.This finding offers new insights into the relationship of microstructure-performance for low-temperature electrolytes,demonstrating that relying solely on inert CIPs can also inhibit the decomposition of the interfacial electrolyte,and inspires a unique design concept for high-performance,commercially viable LIBs that operate reliably in sub-zero environments.
基金supported by the National Natural Science Foundation of China (Grant Nos. 62174019, 52302046, L2424216)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515012139)+2 种基金the Major Program (JD) of Hubei Province (Grant No. 2023BAA009)the Knowledge Innovation Program of Wuhan-Shuguang Project (Grant No. 2023010201020262)the Basic Research Program of Jiangsu (Grant No. BK20230268)。
文摘The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation supported by experimental evidence remains lacking. This work investigates the effects of fluorine incorporation and electrothermal annealing(ETA) on the current transport process at Ni/β-Ga_(2)O_(3) Schottky contacts. X-ray photoelectron spectroscopy and first-principles calculations confirm the presence of fluorine substitutions for oxygen and oxygen vacancies and their lowering effect on the Schottky barrier heights. Additionally, accurate electrothermal hybrid TCAD simulations validates the extremely short-duration high temperatures(683 K) induced by ETA, which facilitates lattice rearrangement and reduces interface trap states. The interface trap states are quantitatively resolved through frequency-dependent conductance technique, showing the trap density(DT)reduction from(0.88-2.48) × 10^(11) cm^(-2)·eV^(-1) to(0.46-2.09) × 10^(11) cm^(-2)·eV^(-1). This investigation offers critical insights into the β-Ga_(2)O_(3) contacts with the collaborative treatment and solids the promotion of high-performance β-Ga_(2)O_(3) power devices.
文摘In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.
基金This work are supported by the Natural Science Foundation of China General Program(Grant No.12272157)the Natural Science Foundation of China Major Program(Grant No.12327901)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2023-ey05)the 111 Project(Grant No.B14044).
文摘The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.
文摘Magnesium and its alloys have gained relevance for their light-weight combined with a high value of strength-to-weight ratio,which makes them useful in fields such as aerospace,automotive as well as biomedical engineering.Unfortunately,the poor corrosion resistance of Mg-alloys limits their wide acceptance.Advanced composite coatings which are self-healing,superhydrophobic anti corrosive,and wear resistant are new synthetic materials for abating these challenges.The superimposed superhydrophobic surfaces help in minimizing their water contact,thus slowing down the electrochemical reactions on the surface of the alloys,while their self-healing characteristics autonomously aid in the repair of any induced micro-crack,defect or damage towards ensuring the metal's long-term protection.In addition,the integration of wear-resistant materials further improves the durability of coatings under mechanical stress.The most recent research efforts have been directed towards the preparation of multifunctional composites,with an emphasis on nanomaterials,functional polymers,and state-of-the-art fabrication techniques in order to take advantage of their synergistic effects.Some of the methods that have so far exhibited promising potentials in fabricating these materials include the sol-gel method,layer-by-layer assembly,and plasma treatments.However,most of the fabricated products are still faced with significant challenges ranging from long-term stability to homogeneous adhesion of the coatings and their scalability for industrial applications.This review discusses the recent progress and the relationship between corrosion inhibition and self-healing efficiencies of wear resistant polymer nanocomposite coatings.Some challenges related to optimizing coating performance were also discussed.In addition,future directions ranging from the consideration of bioinspired designs,novel hybrid nanocomposite materials,and environmentally sustainable solutions integrated with smart protective coatings were also proposed as new wave technologies that can potentially revolutionize the corrosion protection offered by Mg alloys while opening up prospects for improved performance and sustainability.
基金Project(2023YFB2604304)supported by the National Key R&D Program of ChinaProjects(52122810,51978586,51778542,U23A20666,52472458)supported by the National Natural Science Foundation of China+1 种基金Project(K2022G034)supported by the Technology Research and Development Program of China National Railway Group Co.Ltd.Projects(2020JDJQ0033,2023NSFSC0884)supported by Sichuan Province Science and Technology Support Program,China。
文摘The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this paper constructs a transient rolling contact finite element model of the wheel-rail in switch under different ramps using ANSYS/LSDYNA method,and analyzes the tribology and damage characteristics when the wheel passes through the switch at a uniform speed.Our research findings reveal that the vibration induced in the switch rail during the wheel load transfer process leads to a step-like increase in the contact force.Moreover,the interaction between the wheel and the rail primarily involves slip contact,which may significantly contribute to the formation of corrugations on the switch rail.Additionally,the presence of large ramps exacerbates switch rail wear and rolling contact fatigue,resulting in a notable 13.2%increase in switch rail damage under 40‰ramp conditions compared to flat(0‰ramp)conditions.Furthermore,the large ramps can alter the direction of crack propagation,ultimately causing surface spalling of the rail.Therefore,large ramps intensify the dynamic interactions during the wheel load transfer process,further aggravating the crack and spalling damage to the switch rails.
基金supported by the Natural Science Foundation of Heilongjiang Province(No.ZD2021E006)the National Natural Science Foundation of China(Nos.52174075 and 52074110).
文摘The models constructed by particle flow simulation method can effectively simulate the heterogeneous substance characteristics and failure behaviors of rocks.However,existing contact models overlook the rock cracks,and the various simulation methods that do consider cracks still exhibit certain limitations.In this paper,based on Flat-Joint model and Linear Parallel Bond model,a crack contact model considering linked substance in the crack is proposed by splitting the crack contact into two portions:linked portion and unlinked portion for calculation.The new contact model considers the influence of crack closure on the contact force-displacement law.And a better compressive tensile strength ratio(UCS/T)was obtained by limiting the failure of the contact bond to be solely controlled by the contact force and moment of the linked portion.Then,by employing the FISH Model tool within the Particle Flow Code,the contact model was constructed and verified through contact force–displacement experiments and loading-unloading tests with cracked model.Finally,the contact model was tested through simulations of rock mechanics experiments.The results indicate that the contact model can effectively simulate the axial and lateral strain laws of rocks simultaneously and has a relatively good reproduction of the bi-modularity of rocks.
