Micro/nanoplastics(M/NPs)have become pervasive environmental pollutants,posing significant risks to human health through various exposure routes,including ingestion,inhalation,and direct contact.This review systematic...Micro/nanoplastics(M/NPs)have become pervasive environmental pollutants,posing significant risks to human health through various exposure routes,including ingestion,inhalation,and direct contact.This review systematically examined the potential impacts of M/NPs on ocular health,focusing on exposure pathways,toxicological mechanisms,and resultant damage to the eye.Ocular exposure to M/NPs can occur via direct contact and oral ingestion,with the latter potentially leading to the penetration of particles through ocular biological barriers into ocular tissues.The review highlighted that M/NPs can induce adverse effects on the ocular surface,elevate intraocular pressure,and cause abnormalities in the vitreous and retina.Mechanistically,oxidative stress and inflammation are central to M/NP-induced ocular damage,with smaller particles often exhibiting greater toxicity.Overall,this review underscored the potential risks of M/NPs to ocular health and emphasized the need for further research to elucidate exposure mechanisms,toxicological pathways,and mitigation strategies.展开更多
Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always...Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.展开更多
Strategically coupling nanoparticle hybrids and internal thermosensitive molecular switches establishes an innovative paradigm for constructing micro/nanoscale-reconfigurable robots,facilitating energyefficient CO_(2)...Strategically coupling nanoparticle hybrids and internal thermosensitive molecular switches establishes an innovative paradigm for constructing micro/nanoscale-reconfigurable robots,facilitating energyefficient CO_(2) management in life-support systems of confined space.Here,a micro/nano-reconfigurable robot is constructed from the CO_(2) molecular hunters,temperature-sensitive molecular switch,solar photothermal conversion,and magnetically-driven function engines.The molecular hunters within the molecular extension state can capture 6.19 mmol g^(−1) of CO_(2) to form carbamic acid and ammonium bicarbonate.Interestingly,the molecular switch of the robot activates a molecular curling state that facilitates CO_(2) release through nano-reconfiguration,which is mediated by the temperature-sensitive curling of Pluronic F127 molecular chains during the photothermal desorption.Nano-reconfiguration of robot alters the amino microenvironment,including increasing surface electrostatic potential of the amino group and decreasing overall lowest unoccupied molecular orbital energy level.This weakened the nucleophilic attack ability of the amino group toward the adsorption product derivatives,thereby inhibiting the side reactions that generate hard-to-decompose urea structures,achieving the lowest regeneration temperature of 55℃ reported to date.The engine of the robot possesses non-contact magnetically-driven micro-reconfiguration capability to achieve efficient photothermal regeneration while avoiding local overheating.Notably,the robot successfully prolonged the survival time of mice in the sealed container by up to 54.61%,effectively addressing the issue of carbon suffocation in confined spaces.This work significantly enhances life-support systems for deep-space exploration,while stimulating innovations in sustainable carbon management technologies for terrestrial extreme environments.展开更多
Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and intro...Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and introducing CO_(2)nanobubble technology to improve the performance of cement-fly ash-based backfill materials(CFB).The properties including fluidity,setting time,uniaxial compressive strength,elastic modulus,porosity,microstructure and CO_(2)storage performance were systematically studied through methods such as fluidity evaluation,time test,uniaxial compression test,mercury intrusion porosimetry(MIP),scanning electron microscopy-energy dispersive spectroscopy analysis(SEM-EDS),and thermogravimetric-differential thermogravimetric analysis(TG-DTG).The experimental results show that the density and strength of the material are significantly improved under the synergistic effect of fractal dimension and CO_(2)nanobubbles.When the fractal dimension reaches 2.65,the mass ratio of coarse and fine aggregates reaches the optimal balance,and the structural density is greatly improved at the same time.At this time,the uniaxial compressive strength and elastic modulus reach their peak values,with increases of up to 13.46%and 27.47%,respectively.CO_(2)nanobubbles enhance the material properties by promoting hydration reaction and carbonization.At the microscopic level,CO_(2)nanobubble water promotes the formation of C-S-H(hydrated calcium silicate),C-A-S-H(hydrated calcium aluminium silicate)gel and CaCO_(3),which is the main way to enhance the performance.Thermogravimetric studies have shown that when the fractal dimension is 2.65,the dehydration of hydration products and the decarbonization process of CaCO_(3)are most obvious,and CO_(2)nanobubble water promotes the carbonization reaction,making it surpass the natural state.The CO_(2)sequestration quality of cement-fly ash-based materials treated with CO_(2)nanobubble water at different fractal dimensions increased by 12.4wt%to 99.8wt%.The results not only provide scientific insights for the design and implementation of low-carbon filling materials,but also provide a solid theoretical basis for strengthening green mining practices and promoting sustainable resource utilization.展开更多
Modern power systems increasingly depend on interconnected microgrids to enhance reliability and renewable energy utilization.However,the high penetration of intermittent renewable sources often causes frequency devia...Modern power systems increasingly depend on interconnected microgrids to enhance reliability and renewable energy utilization.However,the high penetration of intermittent renewable sources often causes frequency deviations,voltage fluctuations,and poor reactive power coordination,posing serious challenges to grid stability.Conventional Interconnection FlowControllers(IFCs)primarily regulate active power flowand fail to effectively handle dynamic frequency variations or reactive power sharing in multi-microgrid networks.To overcome these limitations,this study proposes an enhanced Interconnection Flow Controller(e-IFC)that integrates frequency response balancing and an Interconnection Reactive Power Flow Controller(IRFC)within a unified adaptive control structure.The proposed e-IFC is implemented and analyzed in DIgSILENT PowerFactory to evaluate its performance under various grid disturbances,including frequency drops,load changes,and reactive power fluctuations.Simulation results reveal that the e-IFC achieves 27.4% higher active power sharing accuracy,19.6% lower reactive power deviation,and 18.2% improved frequency stability compared to the conventional IFC.The adaptive controller ensures seamless transitions between grid-connected and islanded modes and maintains stable operation even under communication delays and data noise.Overall,the proposed e-IFCsignificantly enhances active-reactive power coordination and dynamic stability in renewable-integrated multi-microgrid systems.Future research will focus on coupling the e-IFC with tertiary-level optimization frameworks and conducting hardware-in-the-loop validation to enable its application in large-scale smart microgrid environments.展开更多
Transmission Electron Microscope (TEM) Technology was used to investigate the effect of 25,100 and 200 mg/kg copper on ultra-structure of root tip and leaf blade of wheat. Result showed that serious damage was found w...Transmission Electron Microscope (TEM) Technology was used to investigate the effect of 25,100 and 200 mg/kg copper on ultra-structure of root tip and leaf blade of wheat. Result showed that serious damage was found with Copper of 25,100 and 200 mg/kg. Plasmolysis,concentrated cytoplasm,chloroplast inflation,lamellar structure disturbance,capsule disappearance and disintegration,mitochondria structures ambiguity and vacuolization were all symptoms under Cu stress. There were positive correlation between concentration of coper stress and the degree of injury,and the degree of injury of copper were different in different organelles. Mitochondria were the most sensitive organelles,and there was patient difference in the same organelles of different parts.展开更多
Introduction The endothelial cells(ECs)lining every blood vessel wall constantly expose to the mechanical forces generated by the blood flow.The EC responses to these hemodynamic forces play a critical role in the hom...Introduction The endothelial cells(ECs)lining every blood vessel wall constantly expose to the mechanical forces generated by the blood flow.The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system.In addition to forming a transport barrier between the blood and vessel wall,vascular ECs play important roles in regulating circulation functions.Besides biochemical stimuli,blood flow induced(hemodynamic)mechanical stimuli,such as shear stress,pressure and circumferential stretch,modulate EC morphology and functions by activating mechanosensors,signaling pathways,and gene and protein expressions.The EC responses to the hemodynamic forces(mechano-sensing and transduction)are critical to maintaining normal vascular functions.Failure in the mechano-sensing and transduction leads to serious vascular diseases including hypertension,atherosclerosis,aneurysms and thrombosis,to name a few[1].On the luminal surface of our blood vessels,there is a thin layer called endothelial surface glycocalyx(ESG)which consists of proteoglycans,glycosaminoglycans(GAGs)and glycoproteins.The GAGs in the ESG are heparan sulfate(HS),hyaluronic acid(HA),chondroitin sulfate(CS),and sialic acid(SA)[2].In order to play important roles in vascular functions,such as being a mechanosensor and transducer for the endothelial cells(ECs)to sense the blood flow,a molecular sieve to maintain normal microvessel permeability and a barrier between the circulating cells and endothelial cells forming the vessel wall,the ESG should have an organized structure at the molecular level.Due to the limitations of optical and electron microscopy,the ultra-structure and organization of ESG has not been revealed until recent development of a super high resolution fluorescence optical microscope,STORM(Stochastic Optical Reconstruction Microscopy).The diffraction of a single fluorescence molecule can be described as the point spread function(PSF).When the light of wavelengthλexcites the fluorophore(emitter),the intensity profile of the spot is defined as the PSF with the width^0.6λ/NA,NA is the numerical aperture of the objective.The diffraction-limited image resolution,for a high numerical aperture objective lens,is^200 nm in the lateral direction and^500 nm in the axial direction,for a conventional fluorescence microscope.The key idea of the single-molecule localization microscopy is to light the molecule,in turn,to achieve the nanometer-level accuracy of their position and reconstruction into a super-resolution image,such as STORM.STORM employs photo-switching mechanisms to stochastically activate individual molecules(photo-switchable or photoactivatable fluorophores)within the diffraction-limited region at different times.Then images with sub-diffraction limit resolution are reconstructed from the measured positions of individual fluorophores[3].To trade the super spatial resolution(accuracy),STORM sacrifices its temporal resolution(efficiency)by switching the state and sequentially exciting the emitters at a high density.Rust et al[3]employed organic dyes and fluorescent proteins as photo-switchable emitters to trade temporal resolution for a super spatial resolution(~20 nm lateral and^50 nm axial at present,can go down to a couple of nanometers if using smaller peptides or antibody fragments instead of currently used whole anti-bodies),which is an order of magnitude higher than conventional confocal microscopy.In the current study,we employed STORM to reveal the major ultra-structural components of the ESG,HS and HA,and their organization at the surface of the cultured EC monolayer[4].Materials and methods We used newly acquired Nikon-STORM system to observe the ESG on in vitro EC(bEnd3,mouse brain microvascular endothelial cells)monolayers.After confluency,the bEnd3 cells were immunolabeled with anti-HS,fol-lowed by an ATT0488 conjugated goat anti-mouse IgG,and with biotinylated HA binding protein,followed by an AF647 conjugated anti-biotin.The ESG was then imaged by the STORM with a 100x/1.49 oil immersed lens.Multiple Reporters of ATT0488 and AF647 with alternating illumination were used to acquire the 3D images of HS and HA.The field of 256×256(40×40μm2)of HS and HA at the surface of ECs was obtained based on totally 40,000 of EM-CCD captured images for each reporter at a capturing speed of 19 ms/frame.Results HA is a long molecule weaving into a network which covers the endothelial luminal surface.The diameter of the HA segments is 185.3±44.7 nm,155.5±57.2 nm,and 156.9±56.1 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.In contrast,HS is a shorter molecule,perpendicular to the cell surface.HA and HS are partially overlapped with each other at the endothelial luminal surface.We quantified the length,diameter,orientation,and density of HS at the top,middle and bottom regions of the endothelial surface.The diameter of the observed HS is 191.0±46.0 nm,284.3±71.1 nm,and 184.2±59.6 nm,and the length of the HS is 621.0±75.7 nm,651.0±118.0 nm,and 575.2±105.6 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.For the HS orientation,its angle with the cell surface is 92.9±1.9,88.7±8.2,and 96.2±10.9 degree,respectively,at the top,middle and bottom regions.The angle of 90 degree is perfectly perpendicular to the cell surface.For the HS distribution,the average density is0.398 elements/μm2,0.345 elements/μm2 and 0.665 elements/μm2,respectively,and the distance between the adjacent HS is 1 694.4±628.1 nm,1 844.8±758.5 nm,and 1 221.9±450.7 nm,respectively,at the top,middle and bottom regions.Conclusions Our results suggest that HS plays a major role in mechanosensing and HA plays a major role in the molecular sieve,due to their organization,ultra-structure and distribution.展开更多
The mechanical behavior of cohesive soil is sensitized to drying-wetting cycles under confinements.However,the hydromechanical coupling effect has not been considered in current constitutive models.A macro-micro analy...The mechanical behavior of cohesive soil is sensitized to drying-wetting cycles under confinements.However,the hydromechanical coupling effect has not been considered in current constitutive models.A macro-micro analysis scheme is proposed in this paper to investigate the soil deformation behavior under the coupling of stress and drying-wetting cycles.A new device is developed based on CT(computerized tomography)workstation to apply certain normal and shear stresses on a soil specimen during drying-wetting cycles.A series of tests are conducted on a type of loess with various coupling of stress paths and drying-wetting cycles.At macroscopic level,stress sensor and laser sensor are used to acquire stress and strain,respectively.The shear and volumetric strain increase during the first few drying-wetting cycles and then become stable.The increase of the shear stress level or confining pressure would cause higher increase rate and the value of shear strain in the process of drying-wetting cycles.At microscopic level,the grayscale value(GSV)of CT scanning image is characterized as the proportion of soil particles to voids.A fabric state parameter is proposed to characterize soil microstructures under the influence of stress and drying-wetting cycle.Test results indicate that the macroand micro-responses show high consistence and relevance.The stress and drying-wetting cycles would both induce collapse of the soil microstructure,which dominants degradation of the soil mechanical properties.The evolution of the macro-mechanical property of soil exhibits a positive linear relationship with the micro-evolution of the fabric state parameter.展开更多
基金Supported by the Guangdong Provincial Natural Science Foundation(No.2114050001527).
文摘Micro/nanoplastics(M/NPs)have become pervasive environmental pollutants,posing significant risks to human health through various exposure routes,including ingestion,inhalation,and direct contact.This review systematically examined the potential impacts of M/NPs on ocular health,focusing on exposure pathways,toxicological mechanisms,and resultant damage to the eye.Ocular exposure to M/NPs can occur via direct contact and oral ingestion,with the latter potentially leading to the penetration of particles through ocular biological barriers into ocular tissues.The review highlighted that M/NPs can induce adverse effects on the ocular surface,elevate intraocular pressure,and cause abnormalities in the vitreous and retina.Mechanistically,oxidative stress and inflammation are central to M/NP-induced ocular damage,with smaller particles often exhibiting greater toxicity.Overall,this review underscored the potential risks of M/NPs to ocular health and emphasized the need for further research to elucidate exposure mechanisms,toxicological pathways,and mitigation strategies.
基金supported by Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2022QNRC001)the National Natural Science Foundation of China(No.52273053)the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.21CGA41)。
文摘Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.
基金supported by the National Natural Science Foundation of China(22168008,22378085)the Guangxi Natural Science Foundation(2024GXNSFDA010053)+1 种基金the Technology Development Project of Guangxi Bossco Environmental Protection Technology Co.,Ltd(202100039)Innovation Project of Guangxi Graduate Education(YCBZ2024065).
文摘Strategically coupling nanoparticle hybrids and internal thermosensitive molecular switches establishes an innovative paradigm for constructing micro/nanoscale-reconfigurable robots,facilitating energyefficient CO_(2) management in life-support systems of confined space.Here,a micro/nano-reconfigurable robot is constructed from the CO_(2) molecular hunters,temperature-sensitive molecular switch,solar photothermal conversion,and magnetically-driven function engines.The molecular hunters within the molecular extension state can capture 6.19 mmol g^(−1) of CO_(2) to form carbamic acid and ammonium bicarbonate.Interestingly,the molecular switch of the robot activates a molecular curling state that facilitates CO_(2) release through nano-reconfiguration,which is mediated by the temperature-sensitive curling of Pluronic F127 molecular chains during the photothermal desorption.Nano-reconfiguration of robot alters the amino microenvironment,including increasing surface electrostatic potential of the amino group and decreasing overall lowest unoccupied molecular orbital energy level.This weakened the nucleophilic attack ability of the amino group toward the adsorption product derivatives,thereby inhibiting the side reactions that generate hard-to-decompose urea structures,achieving the lowest regeneration temperature of 55℃ reported to date.The engine of the robot possesses non-contact magnetically-driven micro-reconfiguration capability to achieve efficient photothermal regeneration while avoiding local overheating.Notably,the robot successfully prolonged the survival time of mice in the sealed container by up to 54.61%,effectively addressing the issue of carbon suffocation in confined spaces.This work significantly enhances life-support systems for deep-space exploration,while stimulating innovations in sustainable carbon management technologies for terrestrial extreme environments.
基金financially supported by the China Scholarship Council(CSC)。
文摘Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and introducing CO_(2)nanobubble technology to improve the performance of cement-fly ash-based backfill materials(CFB).The properties including fluidity,setting time,uniaxial compressive strength,elastic modulus,porosity,microstructure and CO_(2)storage performance were systematically studied through methods such as fluidity evaluation,time test,uniaxial compression test,mercury intrusion porosimetry(MIP),scanning electron microscopy-energy dispersive spectroscopy analysis(SEM-EDS),and thermogravimetric-differential thermogravimetric analysis(TG-DTG).The experimental results show that the density and strength of the material are significantly improved under the synergistic effect of fractal dimension and CO_(2)nanobubbles.When the fractal dimension reaches 2.65,the mass ratio of coarse and fine aggregates reaches the optimal balance,and the structural density is greatly improved at the same time.At this time,the uniaxial compressive strength and elastic modulus reach their peak values,with increases of up to 13.46%and 27.47%,respectively.CO_(2)nanobubbles enhance the material properties by promoting hydration reaction and carbonization.At the microscopic level,CO_(2)nanobubble water promotes the formation of C-S-H(hydrated calcium silicate),C-A-S-H(hydrated calcium aluminium silicate)gel and CaCO_(3),which is the main way to enhance the performance.Thermogravimetric studies have shown that when the fractal dimension is 2.65,the dehydration of hydration products and the decarbonization process of CaCO_(3)are most obvious,and CO_(2)nanobubble water promotes the carbonization reaction,making it surpass the natural state.The CO_(2)sequestration quality of cement-fly ash-based materials treated with CO_(2)nanobubble water at different fractal dimensions increased by 12.4wt%to 99.8wt%.The results not only provide scientific insights for the design and implementation of low-carbon filling materials,but also provide a solid theoretical basis for strengthening green mining practices and promoting sustainable resource utilization.
基金the Deanship of Scientific Research at Northern Border University,Arar,Saudi Arabia,for funding this research work through the project number“NBU-FFR-2025-3623-11”.
文摘Modern power systems increasingly depend on interconnected microgrids to enhance reliability and renewable energy utilization.However,the high penetration of intermittent renewable sources often causes frequency deviations,voltage fluctuations,and poor reactive power coordination,posing serious challenges to grid stability.Conventional Interconnection FlowControllers(IFCs)primarily regulate active power flowand fail to effectively handle dynamic frequency variations or reactive power sharing in multi-microgrid networks.To overcome these limitations,this study proposes an enhanced Interconnection Flow Controller(e-IFC)that integrates frequency response balancing and an Interconnection Reactive Power Flow Controller(IRFC)within a unified adaptive control structure.The proposed e-IFC is implemented and analyzed in DIgSILENT PowerFactory to evaluate its performance under various grid disturbances,including frequency drops,load changes,and reactive power fluctuations.Simulation results reveal that the e-IFC achieves 27.4% higher active power sharing accuracy,19.6% lower reactive power deviation,and 18.2% improved frequency stability compared to the conventional IFC.The adaptive controller ensures seamless transitions between grid-connected and islanded modes and maintains stable operation even under communication delays and data noise.Overall,the proposed e-IFCsignificantly enhances active-reactive power coordination and dynamic stability in renewable-integrated multi-microgrid systems.Future research will focus on coupling the e-IFC with tertiary-level optimization frameworks and conducting hardware-in-the-loop validation to enable its application in large-scale smart microgrid environments.
基金Supported by Scientific and Technological Fund from China University of Mining and Technology (D200402)~~
文摘Transmission Electron Microscope (TEM) Technology was used to investigate the effect of 25,100 and 200 mg/kg copper on ultra-structure of root tip and leaf blade of wheat. Result showed that serious damage was found with Copper of 25,100 and 200 mg/kg. Plasmolysis,concentrated cytoplasm,chloroplast inflation,lamellar structure disturbance,capsule disappearance and disintegration,mitochondria structures ambiguity and vacuolization were all symptoms under Cu stress. There were positive correlation between concentration of coper stress and the degree of injury,and the degree of injury of copper were different in different organelles. Mitochondria were the most sensitive organelles,and there was patient difference in the same organelles of different parts.
基金supported by NIH-1SC1CA153325-01,NSF-MRI CBET 1337746 and 1UG3TR002151-01
文摘Introduction The endothelial cells(ECs)lining every blood vessel wall constantly expose to the mechanical forces generated by the blood flow.The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system.In addition to forming a transport barrier between the blood and vessel wall,vascular ECs play important roles in regulating circulation functions.Besides biochemical stimuli,blood flow induced(hemodynamic)mechanical stimuli,such as shear stress,pressure and circumferential stretch,modulate EC morphology and functions by activating mechanosensors,signaling pathways,and gene and protein expressions.The EC responses to the hemodynamic forces(mechano-sensing and transduction)are critical to maintaining normal vascular functions.Failure in the mechano-sensing and transduction leads to serious vascular diseases including hypertension,atherosclerosis,aneurysms and thrombosis,to name a few[1].On the luminal surface of our blood vessels,there is a thin layer called endothelial surface glycocalyx(ESG)which consists of proteoglycans,glycosaminoglycans(GAGs)and glycoproteins.The GAGs in the ESG are heparan sulfate(HS),hyaluronic acid(HA),chondroitin sulfate(CS),and sialic acid(SA)[2].In order to play important roles in vascular functions,such as being a mechanosensor and transducer for the endothelial cells(ECs)to sense the blood flow,a molecular sieve to maintain normal microvessel permeability and a barrier between the circulating cells and endothelial cells forming the vessel wall,the ESG should have an organized structure at the molecular level.Due to the limitations of optical and electron microscopy,the ultra-structure and organization of ESG has not been revealed until recent development of a super high resolution fluorescence optical microscope,STORM(Stochastic Optical Reconstruction Microscopy).The diffraction of a single fluorescence molecule can be described as the point spread function(PSF).When the light of wavelengthλexcites the fluorophore(emitter),the intensity profile of the spot is defined as the PSF with the width^0.6λ/NA,NA is the numerical aperture of the objective.The diffraction-limited image resolution,for a high numerical aperture objective lens,is^200 nm in the lateral direction and^500 nm in the axial direction,for a conventional fluorescence microscope.The key idea of the single-molecule localization microscopy is to light the molecule,in turn,to achieve the nanometer-level accuracy of their position and reconstruction into a super-resolution image,such as STORM.STORM employs photo-switching mechanisms to stochastically activate individual molecules(photo-switchable or photoactivatable fluorophores)within the diffraction-limited region at different times.Then images with sub-diffraction limit resolution are reconstructed from the measured positions of individual fluorophores[3].To trade the super spatial resolution(accuracy),STORM sacrifices its temporal resolution(efficiency)by switching the state and sequentially exciting the emitters at a high density.Rust et al[3]employed organic dyes and fluorescent proteins as photo-switchable emitters to trade temporal resolution for a super spatial resolution(~20 nm lateral and^50 nm axial at present,can go down to a couple of nanometers if using smaller peptides or antibody fragments instead of currently used whole anti-bodies),which is an order of magnitude higher than conventional confocal microscopy.In the current study,we employed STORM to reveal the major ultra-structural components of the ESG,HS and HA,and their organization at the surface of the cultured EC monolayer[4].Materials and methods We used newly acquired Nikon-STORM system to observe the ESG on in vitro EC(bEnd3,mouse brain microvascular endothelial cells)monolayers.After confluency,the bEnd3 cells were immunolabeled with anti-HS,fol-lowed by an ATT0488 conjugated goat anti-mouse IgG,and with biotinylated HA binding protein,followed by an AF647 conjugated anti-biotin.The ESG was then imaged by the STORM with a 100x/1.49 oil immersed lens.Multiple Reporters of ATT0488 and AF647 with alternating illumination were used to acquire the 3D images of HS and HA.The field of 256×256(40×40μm2)of HS and HA at the surface of ECs was obtained based on totally 40,000 of EM-CCD captured images for each reporter at a capturing speed of 19 ms/frame.Results HA is a long molecule weaving into a network which covers the endothelial luminal surface.The diameter of the HA segments is 185.3±44.7 nm,155.5±57.2 nm,and 156.9±56.1 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.In contrast,HS is a shorter molecule,perpendicular to the cell surface.HA and HS are partially overlapped with each other at the endothelial luminal surface.We quantified the length,diameter,orientation,and density of HS at the top,middle and bottom regions of the endothelial surface.The diameter of the observed HS is 191.0±46.0 nm,284.3±71.1 nm,and 184.2±59.6 nm,and the length of the HS is 621.0±75.7 nm,651.0±118.0 nm,and 575.2±105.6 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.For the HS orientation,its angle with the cell surface is 92.9±1.9,88.7±8.2,and 96.2±10.9 degree,respectively,at the top,middle and bottom regions.The angle of 90 degree is perfectly perpendicular to the cell surface.For the HS distribution,the average density is0.398 elements/μm2,0.345 elements/μm2 and 0.665 elements/μm2,respectively,and the distance between the adjacent HS is 1 694.4±628.1 nm,1 844.8±758.5 nm,and 1 221.9±450.7 nm,respectively,at the top,middle and bottom regions.Conclusions Our results suggest that HS plays a major role in mechanosensing and HA plays a major role in the molecular sieve,due to their organization,ultra-structure and distribution.
基金funded by National Key R&D Program of China(Grant No.2023YFC3007001)Beijing Natural Science Foundation(Grant No.8244053)China Postdoctoral Science Foundation(Grant No.2024M754065).
文摘The mechanical behavior of cohesive soil is sensitized to drying-wetting cycles under confinements.However,the hydromechanical coupling effect has not been considered in current constitutive models.A macro-micro analysis scheme is proposed in this paper to investigate the soil deformation behavior under the coupling of stress and drying-wetting cycles.A new device is developed based on CT(computerized tomography)workstation to apply certain normal and shear stresses on a soil specimen during drying-wetting cycles.A series of tests are conducted on a type of loess with various coupling of stress paths and drying-wetting cycles.At macroscopic level,stress sensor and laser sensor are used to acquire stress and strain,respectively.The shear and volumetric strain increase during the first few drying-wetting cycles and then become stable.The increase of the shear stress level or confining pressure would cause higher increase rate and the value of shear strain in the process of drying-wetting cycles.At microscopic level,the grayscale value(GSV)of CT scanning image is characterized as the proportion of soil particles to voids.A fabric state parameter is proposed to characterize soil microstructures under the influence of stress and drying-wetting cycle.Test results indicate that the macroand micro-responses show high consistence and relevance.The stress and drying-wetting cycles would both induce collapse of the soil microstructure,which dominants degradation of the soil mechanical properties.The evolution of the macro-mechanical property of soil exhibits a positive linear relationship with the micro-evolution of the fabric state parameter.
