A non-classical Kirchhoff plate model is developed for the dynamic analysis of microscale plates based on the modified couple stress theory in which an internal material length scale parameter is included. Unlike the ...A non-classical Kirchhoff plate model is developed for the dynamic analysis of microscale plates based on the modified couple stress theory in which an internal material length scale parameter is included. Unlike the classical Kirchhoff plate model, the newly developed model can capture the size effect of microscale plates. Two boundary value problems of rectangular micro- plates are solved and the size effect on the lowest two natural frequencies is investigated. It is shown that the natural frequencies of the microscale plates predicted by the current model are size-dependent when the plate thickness is comparable to the material length scale parameter.展开更多
Bioprinting has been widely investigated for tissue engineering and regenerative medicine applications.However,it is still difficult to reconstruct the complex native cell arrangement due to the limited printing resol...Bioprinting has been widely investigated for tissue engineering and regenerative medicine applications.However,it is still difficult to reconstruct the complex native cell arrangement due to the limited printing resolution of conventional bioprinting techniques such as extrusion-and inkjet-based printing.Recently,an electrohydrodynamic(EHD)bioprinting strategy was reported for the precise deposition of well-organized cell-laden constructs with microscale filament size,whereas few studies have been devoted to developing bioinks that can be applied for EHD bioprinting and simultaneously support cell spreading.This study describes functionalized alginate-based bioinks for microscale EHD bioprinting using peptide grafting and fibrin incorporation,which leads to high cell viability(>90%)and cell spreading.The printed filaments can be further refined to as small as 30μm by incorporating polyoxyethylene and remained stable over one week when exposed to an aqueous environment.By utilizing the presented alginate-based bioinks,layer-specific cell alignment along the printing struts could be observed inside the EHD-printed microscale filaments,which allows fabricating living constructs with cell-scale filament resolution for guided cellular orientation.展开更多
Many structures and materials in nature and physiology have important ＂meso-scale＂ structures at the micron lengthscale whose tensile responses have proven difficult to characterize mechanically. Although techniques...Many structures and materials in nature and physiology have important ＂meso-scale＂ structures at the micron lengthscale whose tensile responses have proven difficult to characterize mechanically. Although techniques such as atomic force microscopy and micro- and nano-identation are mature for compression and indentation testing at the nano-scale, and standard uniaxial and shear rheometry techniques exist for the macroscale, few techniques are applicable for tensile-testing at the micrometre-scale, leaving a gap in our understanding of hierarchical biomaterials. Here, we present a novel magnetic mechanical testing （MMT） system that enables viscoelastic tensile testing at this critical length scale. The MMT system applies non-contact loading, avoiding gripping and surface interaction effects. We demonstrate application of the MMT system to the first analyses of the pure tensile responses of several native and engineered tissue systems at the mesoscale, showing the broad potential of the system for exploring micro- and meso-scale analysis of structured and hierarchical biological systems.展开更多
In situ microscale distributions of 02, H2S, pH and redox potential in sediments of Hongfeng Lake, SW China, were investigated using the powerful microsensor technique. Our results show that O2 was depleted within the...In situ microscale distributions of 02, H2S, pH and redox potential in sediments of Hongfeng Lake, SW China, were investigated using the powerful microsensor technique. Our results show that O2 was depleted within the top 3.9 mm in surface sediments, and H2S was subsequently detected at -6.0 mm depth, and reached its maximum concentrations at -25 mm. The degradation of organic matter and reduction of sulfate might be the major pathways of producing H2S in sediments, pH rapidly reduced in surface layers mainly due to H＋ release in the oxidation of organic matter. Eh also decreased sharply in surface sediments, probabl indicating the coexistence of Fe and Mn oxides with O2 in aerobic region. Furthermore, the programme of PROFILE was applied to model the 02 gradient, and good fit was obtained between the simulative values and the factual values both in sediments and in the diffusive boundary layer （DBL）. The results indicate that the depth-integrated O2 consumption rates within sediments were 0.083 and 0.134 nmol·m-3·s-1 in site S1 and site S2, respectively. In addition, there were distinct DBL in two sediment profiles, with 1.2 mm thickness in S1 and 0.9 mm thickness in S2. The diffusive fluxes of O2 within the DBL were 67.13 nmol·m-2·s-1 in S1 and 88.54 nmol·m-2·s-1 in S2.展开更多
Manipulating the fluid transport in the microscale pores and channels is playing a paramount role in the realization of the versatile functions of microfluidics.In recent years,using light to control the fluid behavio...Manipulating the fluid transport in the microscale pores and channels is playing a paramount role in the realization of the versatile functions of microfluidics.In recent years,using light to control the fluid behavior in the microchannels/pores has attracted many researchers'attention due to the advantages of light such as non-contact stimulation,tunable excitation,high spatial and temporal resolution.With efforts,great achievements and progresses have been achieved for photochemical effect driven microscale flow control,including fluid pumping,flow rate control,and fluid mixing,etc.In this review,we discuss the responsive mechanisms of photochemical effect driven fluid behavior control at the microscale.We also give a comprehensive review on the latest research progresses in photochemical effect controlled microfluid behaviors.Besides,prospective opportunities for the future development of light control of microscale flow are provided to attract scientific interest for the fast development and applications of various microchannel/pore systems.展开更多
The construction and characteristics of a microscale long-optical-path electrochemi- cal cell with a plug-in thin-layer electrode are described.Using ferricyanide as the test species,the thermodynamic parameters of el...The construction and characteristics of a microscale long-optical-path electrochemi- cal cell with a plug-in thin-layer electrode are described.Using ferricyanide as the test species,the thermodynamic parameters of electron transfer processes are determined at car- bon,plantinum,and gold electrodes.展开更多
Spacesuits and spacecraft must endure high velocity impacts from micrometeoroids. This work considers the impact of 100 μm diameter projectiles into composite targets at velocities from 0.5 km/s to 2 km/s.This work b...Spacesuits and spacecraft must endure high velocity impacts from micrometeoroids. This work considers the impact of 100 μm diameter projectiles into composite targets at velocities from 0.5 km/s to 2 km/s.This work begins by presenting an energy-based theoretical model relating depth of penetration(Do P)and impact force to impact velocity, characteristic time, and threshold velocity and force. Next, this work compares numerical simulations of normal impact on composites to the theoretical model. Numerical simulations are conducted with LS-DYNA and the well-known composite model, MAT-162. The numerical models consider unidirectional S2-glass fiber reinforced SC-15 epoxy composite laminates. The numerical model shows good correlation with the theoretical model. The numerical model also investigates lateral impact, parallel to the fiber direction, and oblique impact at angles from 30°to 82.5°.This work decomposes oblique impact into normal and lateral components, and compares them with normal and lateral impact results. The results show good correlation of the normal component of oblique results with the theoretical model. This numerical and theoretical study focuses on Do P, velocity, and penetration resistance force as functions of time. The theoretical model and numerical simulations are used to determine new Do P parameters: characteristic time of depth of penetration and threshold impact velocity. These models are a first step in developing the capability to predict Do P for oblique,microscale, high-speed impact on composite materials.展开更多
The exploration of Mars would heavily rely on Martian rocks mechanics and engineering technology.As the mechanical property of Martian rocks is uncertain,it is of utmost importance to predict the probability distribut...The exploration of Mars would heavily rely on Martian rocks mechanics and engineering technology.As the mechanical property of Martian rocks is uncertain,it is of utmost importance to predict the probability distribution of Martian rocks mechanical property for the success of Mars exploration.In this paper,a fast and accurate probability distribution method for predicting the macroscale elastic modulus of Martian rocks was proposed by integrating the microscale rock mechanical experiments(micro-RME),accurate grain-based modeling(AGBM)and upscaling methods based on reliability principles.Firstly,the microstructure of NWA12564 Martian sample and elastic modulus of each mineral were obtained by micro-RME with TESCAN integrated mineral analyzer(TIMA)and nanoindentation.The best probability distribution function of the minerals was determined by Kolmogorov-Smirnov(K-S)test.Secondly,based on best distribution function of each mineral,the Monte Carlo simulations(MCS)and upscaling methods were implemented to obtain the probability distribution of upscaled elastic modulus.Thirdly,the correlation between the upscaled elastic modulus and macroscale elastic modulus obtained by AGBM was established.The accurate probability distribution of the macroscale elastic modulus was obtained by this correlation relationship.The proposed method can predict the probability distribution of Martian rocks mechanical property with any size and shape samples.展开更多
A new method for selecting dimensionless relaxation time in the lattice Boltzmann model was proposed based on similarity criterion and gas true physical parameters.At the same time,the dimensionless relaxation time wa...A new method for selecting dimensionless relaxation time in the lattice Boltzmann model was proposed based on similarity criterion and gas true physical parameters.At the same time,the dimensionless relaxation time was modified by considering the influence of the boundary Knudsen layer.On this basis,the second-order slip boundary condition of the wall was considered,and the key parameters in the corresponding combined bounce-back/specular-reflection boundary condition were deduced to build a new model of unconventional gas microscale flow simulation based on the lattice Boltzmann method suitable for high temperatures and high pressures.The simulation results of methane gas flow driven by body force in infinite micro-channels and flow driven by inlet-outlet pressure differential in long straight channels were compared with the numerical and analytical solutions in the literature to verify the accuracy of the model,and the dimensionless relaxation time modification was formally optimized.The results show that the new model can effectively characterize the slippage effect,compression effect,gas density and the effect of boundary Knudsen layer in the micro-scale flow of unconventional natural gas.The new model can achieve a more comprehensive characterization of the real gas flow conditions and can be used as a basic model for the simulation of unconventional gas flow on the micro-nano scale.展开更多
Microscale stray grains(MSGs),which are composed of misoriented and fragmented high-ordered dendrite arms,small-sized equiaxed grains,and columnar grains,are a novel grain defect that occurs within the shrouds of sing...Microscale stray grains(MSGs),which are composed of misoriented and fragmented high-ordered dendrite arms,small-sized equiaxed grains,and columnar grains,are a novel grain defect that occurs within the shrouds of single-crystal(SC)blades made from Ni-based superalloy.State-of-the-art non-destructive testing methods are incapable of detecting this defect,resulting in a high-risk application of SC blades.This study aims to control this defect by systematically investigating directional solidification processing parameters,shroud dimensions,and rhenium(Re)content in the formation of MSG defects.The results reveal that the defect forms exclusively at the overhanging extremities of the upper shrouds on the back side of the blades that face the heater.Increasing the withdrawal rate reduces the occurrence of MSG defects.As the shroud dimensions increase,MSG defects appear in the transition area between the downward suspended extremity of the blade shroud and the side of the blade body,as well as near the corner of the downward suspended extremity of the shroud.The occurrence of MSG defects increases with increasing shroud dimensions.Varying Re content sharply decreases the formation of MSG defects.A concentration-attached Rayleigh-Taylor instability(RTI)superheating(CARTISH)model,considering solidification shrinkage,was proposed to comprehend the formation of MSG defects.Simulation results based on this model are consistent with the experimentally observed distribution and degree of MSG defects under different conditions.Effective control of the CARTISH is critical to managing MSG defects.展开更多
Loop Heat Pipe (LHP) performance strongly depends on the performance of a wick that is porous media inserted in an evaporator. In this paper, the visualization results of thermo-fluid behavior on the surface of the wi...Loop Heat Pipe (LHP) performance strongly depends on the performance of a wick that is porous media inserted in an evaporator. In this paper, the visualization results of thermo-fluid behavior on the surface of the wick with microscopic infrared thermography were reported. In this study, 2 different samples that simulated a part of wick in the evaporator were used. The wicks were made by different two materials: polytetrafluoroethylene (PTFE) and stainless steel (SUS). The pore radii of PTFE wick and SUS wick are 1.2 μm and 22.5 μm. The difference of thermo-fluid behavior that was caused by the difference of material was investigated. These two materials include 4 different properties: pore radius, thermal conductivity, permeability and porosity. In order to investigate the effect of the thermal conductivity on wick’s operating mode, the phase diagram on the q-k<sub>eff</sub> plane was made. Based on the temperature line profiles, two operating modes: mode of heat conduction and mode of convection were observed. The effective thermal conductivity of the porous media has strong effect on the operating modes. In addition, the difference of heat leak through the wick that was caused by the difference of the material was discussed.展开更多
Microscale chemistry is appealing to all levels of education.In contrast to conventional macroscale chemistry,only minute amount of chemicals are required to undertaking a chemical investigation.……
Microscale laboratory is environmentally benign as the amount of reagents,waste,energy and cost can be reduced dramatically,and exposure to potentially toxic chemicals is diminished.……
Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the o...Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.展开更多
The rapid rise of artificial intelligence(AI)-integrated electronics,has created an urgent demand for microscale energy storage systems that are not only compact but also capable of intelligent interaction,rapid respo...The rapid rise of artificial intelligence(AI)-integrated electronics,has created an urgent demand for microscale energy storage systems that are not only compact but also capable of intelligent interaction,rapid responsiveness,and seamless system-level integration.Traditional power sources struggle to meet the stringent requirements of miniaturized and multifunctional electronics,where device footprints shrink to the sub-centimeter or even millimeter scale while functionality expands toward adaptive sensing,and wireless communication.展开更多
Solid-state phosphorescent materials with stimulus-responsive properties have been widely developed for diverse applications.However,the task of generating excited states with long lifetimes in aqueous solution remain...Solid-state phosphorescent materials with stimulus-responsive properties have been widely developed for diverse applications.However,the task of generating excited states with long lifetimes in aqueous solution remains challenging due to the ultrafast deactivation of the triplet excitons and the difficulty in regulating stimulation sites in an aqueous environment.Additionally,most existing materials are primarily responsive to limited stimuli,such as light,oxygen,or temperature.Here,we present a microscale rigid framework engineering strategy that can be used to modulate the phosphorescence properties of carbon nanodots(CNDs),by brightening triplet excitons through ultrasound-enhanced rigidity in CNDs.Ultrasound-responsive phosphorescent CNDs with a lifetime of 1.25 seconds in an aqueous solution were achieved.The CNDs exhibit high sensitivity to surrounding ultrasound,showing a linear response to ultrasound exposure during the treatment period.The ultrasound-responsive phosphorescent CNDs demonstrate potential applications as sensing units in ultrasound radar detection and in vivo afterglow imaging.展开更多
CONSPECTUS:Electrochemical devices are typically designed for operation over a narrow pH range and are constrained in the choice of catalysts and operating potentials by the pH environment of the electrodes.This is th...CONSPECTUS:Electrochemical devices are typically designed for operation over a narrow pH range and are constrained in the choice of catalysts and operating potentials by the pH environment of the electrodes.This is the result of a heretofore lack of a viable strategy to maintain pH gradients between the electrodes over practically significant time durations with only a minimal impact on the device performance.While bipolar interfaces are wellknown,they typically result in high junction potential losses that make them impractical in real-life systems.We have demonstrated a way to overcome this long-standing challenge using our tailormade,microscale bipolar interfaces,which allows the use of acidic electrolytes at one electrode and alkaline electrolytes at the other,without mixing over time.展开更多
Since the invention of optical tweezers,optical manipulation has advanced significantly in scientific areas such as atomic physics,optics and biological science.Especially in the past decade,numerous optical beams and...Since the invention of optical tweezers,optical manipulation has advanced significantly in scientific areas such as atomic physics,optics and biological science.Especially in the past decade,numerous optical beams and nanoscale devices have been proposed to mechanically act on nanoparticles in increasingly precise,stable and flexible ways.Both the linear and angular momenta of light can be exploited to produce optical tractor beams,tweezers and optical torque from the microscale to the nanoscale.Research on optical forces helps to reveal the nature of light–matter interactions and to resolve the fundamental aspects,which require an appropriate description of momenta and the forces on objects in matter.In this review,starting from basic theories and computational approaches,we highlight the latest optical trapping configurations and their applications in bioscience,as well as recent advances down to the nanoscale.Finally,we discuss the future prospects of nanomanipulation,which has considerable potential applications in a variety of scientific fields and everyday life.展开更多
Based on constructal theory,the constructs of three"volume-point"heat conduction models with three-dimensional cylindrical element and rectangular and triangular elements on microscale and nanoscale are opti...Based on constructal theory,the constructs of three"volume-point"heat conduction models with three-dimensional cylindrical element and rectangular and triangular elements on microscale and nanoscale are optimized by taking minimum entransy dissipation rate as optimization objective.The optimal constructs of the three"volume-point"heat conduction models with minimum dimensionless equivalent thermal resistance are obtained.The results show that the optimal constructs of the three-dimensional cylindrical assembly based on the minimizations of dimensionless equivalent thermal resistance and dimensionless maximum thermal resistance are different,which is obviously different from the comparison between those of the corresponding two-dimensional rectangular assembly based on the minimizations of these two objectives.The optimal constructs based on rectangular and triangular elements on microscale and nanoscale when the size effect takes effect are obviously different from those when the size effect does not take effect.Because the thermal current density in the high conductivity channel of the rectangular and triangular second order assemblies are not linear with the length,the optimal constructs of these assemblies based on the minimization of entransy dissipation rate are different from those based on the minimization of maximum temperature difference.The dimensionless equivalent thermal resistance defined based on entransy dissipation rate reflects the average heat transfer performance of the construct.The studies on"volume-point"heat conduction constructal problems at three-dimensional conditions and microscale and nanoscale by taking minimum entransy dissipation rate as optimization objective extend the application range of the entransy dissipation extremum principle.展开更多
Background:Endometrial cancer is one of the most common malignancies of the reproductive system.Effective and cost-effective screening method for populations at high risk is not available.This study aimed to investiga...Background:Endometrial cancer is one of the most common malignancies of the reproductive system.Effective and cost-effective screening method for populations at high risk is not available.This study aimed to investigate specimen adequacy and the influencing factors in microscale endometrial sampling biopsy and to evaluate the diagnostic accuracy and medical cost of biopsy in endometrial cancer and atypical hyperplasia screenings in comparison with hysteroscopic endometrial biopsy.Methods:A total of 1551 patients at high risk for endometrial lesions who required hysteroscopic endometrial biopsy from November 2017 to August 2018 were included.Microscale endometrial sampling biopsy was performed,followed by hysteroscopic endometrial biopsy.We evaluated the specimen adequacy and influencing factors of microscale endometrial sampling.Diagnostic consistency between microscale endometrial sampling biopsy and hysteroscopic endometrial biopsy was evaluated.The sensitivity,specificity,positive predictive value,and negative predictive value of microscale endometrial sampling biopsy in screening for endometrial cancer and atypical hyperplasia were analyzed,and the medical costs of the two procedures were compared.Results:The specimen adequacy was 81.2%.Patient age,menopausal status,endometrial thickness,and endometrial lesion type were correlated with specimen adequacy.There was good consistency in distinguishing benign and malignant endometrial diseases between microscale endometrial sampling biopsy and hysteroscopic biopsy(kappa 0.950,95%CI 0.925-0.975).The sensitivity,specificity,positive predictive value,and negative predictive value of microscale endometrial sampling biopsy were 91.7%,100.0%,100.0%,and 99.3%for endometrial cancer screening,respectively,and 82.0%,100.0%,100.0%,and 99.4%for atypical hyperplasia screening.The medical cost of endometrial sampling biopsy was only 22.1%of the cost of hysteroscopic biopsy.Conclusions:Microscale endometrial sampling biopsy is a minimally invasive alternative technique for obtaining adequate endometrial specimens for histopathological examination.It has the potential to be used in detecting endometrial cancer and atypical hyperplasia with high efficiency and low cost.展开更多
文摘A non-classical Kirchhoff plate model is developed for the dynamic analysis of microscale plates based on the modified couple stress theory in which an internal material length scale parameter is included. Unlike the classical Kirchhoff plate model, the newly developed model can capture the size effect of microscale plates. Two boundary value problems of rectangular micro- plates are solved and the size effect on the lowest two natural frequencies is investigated. It is shown that the natural frequencies of the microscale plates predicted by the current model are size-dependent when the plate thickness is comparable to the material length scale parameter.
基金This work was financially supported by the National Key Research and Development Program of China(No.2018YFA0703003)the National Natural Science Foundation of China(No.52125501)+1 种基金the Key Research Project of Shaanxi Province(Nos.2021LLRH-08,2020GXLH-Y-021,and 2021GXLH-Z-028)the Youth InnovationTeam of Shaanxi Universities and the Fundamental Research Funds for the Central Universities.
文摘Bioprinting has been widely investigated for tissue engineering and regenerative medicine applications.However,it is still difficult to reconstruct the complex native cell arrangement due to the limited printing resolution of conventional bioprinting techniques such as extrusion-and inkjet-based printing.Recently,an electrohydrodynamic(EHD)bioprinting strategy was reported for the precise deposition of well-organized cell-laden constructs with microscale filament size,whereas few studies have been devoted to developing bioinks that can be applied for EHD bioprinting and simultaneously support cell spreading.This study describes functionalized alginate-based bioinks for microscale EHD bioprinting using peptide grafting and fibrin incorporation,which leads to high cell viability(>90%)and cell spreading.The printed filaments can be further refined to as small as 30μm by incorporating polyoxyethylene and remained stable over one week when exposed to an aqueous environment.By utilizing the presented alginate-based bioinks,layer-specific cell alignment along the printing struts could be observed inside the EHD-printed microscale filaments,which allows fabricating living constructs with cell-scale filament resolution for guided cellular orientation.
基金partially supported by the National Natural Science Foundation of China(Grants 11532009,11372243,and 11522219)the China Postdoctoral Science Foundation(Grant 2016M602810)This project was also supported by the Initiative Postdocs Supporting Program(Grant BX201600121)
文摘Many structures and materials in nature and physiology have important ＂meso-scale＂ structures at the micron lengthscale whose tensile responses have proven difficult to characterize mechanically. Although techniques such as atomic force microscopy and micro- and nano-identation are mature for compression and indentation testing at the nano-scale, and standard uniaxial and shear rheometry techniques exist for the macroscale, few techniques are applicable for tensile-testing at the micrometre-scale, leaving a gap in our understanding of hierarchical biomaterials. Here, we present a novel magnetic mechanical testing （MMT） system that enables viscoelastic tensile testing at this critical length scale. The MMT system applies non-contact loading, avoiding gripping and surface interaction effects. We demonstrate application of the MMT system to the first analyses of the pure tensile responses of several native and engineered tissue systems at the mesoscale, showing the broad potential of the system for exploring micro- and meso-scale analysis of structured and hierarchical biological systems.
基金supported by the National Natural Science Foundation of China (Nos.41173125 and 41403113)
文摘In situ microscale distributions of 02, H2S, pH and redox potential in sediments of Hongfeng Lake, SW China, were investigated using the powerful microsensor technique. Our results show that O2 was depleted within the top 3.9 mm in surface sediments, and H2S was subsequently detected at -6.0 mm depth, and reached its maximum concentrations at -25 mm. The degradation of organic matter and reduction of sulfate might be the major pathways of producing H2S in sediments, pH rapidly reduced in surface layers mainly due to H＋ release in the oxidation of organic matter. Eh also decreased sharply in surface sediments, probabl indicating the coexistence of Fe and Mn oxides with O2 in aerobic region. Furthermore, the programme of PROFILE was applied to model the 02 gradient, and good fit was obtained between the simulative values and the factual values both in sediments and in the diffusive boundary layer （DBL）. The results indicate that the depth-integrated O2 consumption rates within sediments were 0.083 and 0.134 nmol·m-3·s-1 in site S1 and site S2, respectively. In addition, there were distinct DBL in two sediment profiles, with 1.2 mm thickness in S1 and 0.9 mm thickness in S2. The diffusive fluxes of O2 within the DBL were 67.13 nmol·m-2·s-1 in S1 and 88.54 nmol·m-2·s-1 in S2.
基金supported by the National Natural Science Foundation of China(Nos.52025132,21975209 and 22005255)the National Key R&D Program of China(No.2018YFA0209500)+1 种基金the Overseas Expertise Introduction Project for Discipline Innovation(111Project,No.B16029)the Fundamental Research Funds for the Central Universities(No.20720190037)。
文摘Manipulating the fluid transport in the microscale pores and channels is playing a paramount role in the realization of the versatile functions of microfluidics.In recent years,using light to control the fluid behavior in the microchannels/pores has attracted many researchers'attention due to the advantages of light such as non-contact stimulation,tunable excitation,high spatial and temporal resolution.With efforts,great achievements and progresses have been achieved for photochemical effect driven microscale flow control,including fluid pumping,flow rate control,and fluid mixing,etc.In this review,we discuss the responsive mechanisms of photochemical effect driven fluid behavior control at the microscale.We also give a comprehensive review on the latest research progresses in photochemical effect controlled microfluid behaviors.Besides,prospective opportunities for the future development of light control of microscale flow are provided to attract scientific interest for the fast development and applications of various microchannel/pore systems.
文摘The construction and characteristics of a microscale long-optical-path electrochemi- cal cell with a plug-in thin-layer electrode are described.Using ferricyanide as the test species,the thermodynamic parameters of electron transfer processes are determined at car- bon,plantinum,and gold electrodes.
基金NASA/EPSCo R Research Infrastructure Development in Delaware (NASA Award NNX15AK34A)sponsored in part by the U.S. Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-12-2-0022 and W911NF-13-2-0027supported in part by funding from the U.S. Army Educational Outreach Program’s Undergraduate Research Apprentice Program, which funded an undergraduate student to gain research experience
文摘Spacesuits and spacecraft must endure high velocity impacts from micrometeoroids. This work considers the impact of 100 μm diameter projectiles into composite targets at velocities from 0.5 km/s to 2 km/s.This work begins by presenting an energy-based theoretical model relating depth of penetration(Do P)and impact force to impact velocity, characteristic time, and threshold velocity and force. Next, this work compares numerical simulations of normal impact on composites to the theoretical model. Numerical simulations are conducted with LS-DYNA and the well-known composite model, MAT-162. The numerical models consider unidirectional S2-glass fiber reinforced SC-15 epoxy composite laminates. The numerical model shows good correlation with the theoretical model. The numerical model also investigates lateral impact, parallel to the fiber direction, and oblique impact at angles from 30°to 82.5°.This work decomposes oblique impact into normal and lateral components, and compares them with normal and lateral impact results. The results show good correlation of the normal component of oblique results with the theoretical model. This numerical and theoretical study focuses on Do P, velocity, and penetration resistance force as functions of time. The theoretical model and numerical simulations are used to determine new Do P parameters: characteristic time of depth of penetration and threshold impact velocity. These models are a first step in developing the capability to predict Do P for oblique,microscale, high-speed impact on composite materials.
文摘The exploration of Mars would heavily rely on Martian rocks mechanics and engineering technology.As the mechanical property of Martian rocks is uncertain,it is of utmost importance to predict the probability distribution of Martian rocks mechanical property for the success of Mars exploration.In this paper,a fast and accurate probability distribution method for predicting the macroscale elastic modulus of Martian rocks was proposed by integrating the microscale rock mechanical experiments(micro-RME),accurate grain-based modeling(AGBM)and upscaling methods based on reliability principles.Firstly,the microstructure of NWA12564 Martian sample and elastic modulus of each mineral were obtained by micro-RME with TESCAN integrated mineral analyzer(TIMA)and nanoindentation.The best probability distribution function of the minerals was determined by Kolmogorov-Smirnov(K-S)test.Secondly,based on best distribution function of each mineral,the Monte Carlo simulations(MCS)and upscaling methods were implemented to obtain the probability distribution of upscaled elastic modulus.Thirdly,the correlation between the upscaled elastic modulus and macroscale elastic modulus obtained by AGBM was established.The accurate probability distribution of the macroscale elastic modulus was obtained by this correlation relationship.The proposed method can predict the probability distribution of Martian rocks mechanical property with any size and shape samples.
基金Supported by National Natural Science Foundation of China(Key Program)(51534006)National Natural Science Foundation of China(51874251)。
文摘A new method for selecting dimensionless relaxation time in the lattice Boltzmann model was proposed based on similarity criterion and gas true physical parameters.At the same time,the dimensionless relaxation time was modified by considering the influence of the boundary Knudsen layer.On this basis,the second-order slip boundary condition of the wall was considered,and the key parameters in the corresponding combined bounce-back/specular-reflection boundary condition were deduced to build a new model of unconventional gas microscale flow simulation based on the lattice Boltzmann method suitable for high temperatures and high pressures.The simulation results of methane gas flow driven by body force in infinite micro-channels and flow driven by inlet-outlet pressure differential in long straight channels were compared with the numerical and analytical solutions in the literature to verify the accuracy of the model,and the dimensionless relaxation time modification was formally optimized.The results show that the new model can effectively characterize the slippage effect,compression effect,gas density and the effect of boundary Knudsen layer in the micro-scale flow of unconventional natural gas.The new model can achieve a more comprehensive characterization of the real gas flow conditions and can be used as a basic model for the simulation of unconventional gas flow on the micro-nano scale.
基金supported by the National Youth Talent Support Program,the National Science and Technology Major Project(No.HT-J2019-VI-0020-0136)the Excellent Youth Foundation of Shaanxi Province of China(No.2021JC-08)+1 种基金the Natural Science Basic Research Plan in Shaanxi Province of China(No.2022JQ-553)the China Postdoctoral Science Foundation(No.2021M692555).
文摘Microscale stray grains(MSGs),which are composed of misoriented and fragmented high-ordered dendrite arms,small-sized equiaxed grains,and columnar grains,are a novel grain defect that occurs within the shrouds of single-crystal(SC)blades made from Ni-based superalloy.State-of-the-art non-destructive testing methods are incapable of detecting this defect,resulting in a high-risk application of SC blades.This study aims to control this defect by systematically investigating directional solidification processing parameters,shroud dimensions,and rhenium(Re)content in the formation of MSG defects.The results reveal that the defect forms exclusively at the overhanging extremities of the upper shrouds on the back side of the blades that face the heater.Increasing the withdrawal rate reduces the occurrence of MSG defects.As the shroud dimensions increase,MSG defects appear in the transition area between the downward suspended extremity of the blade shroud and the side of the blade body,as well as near the corner of the downward suspended extremity of the shroud.The occurrence of MSG defects increases with increasing shroud dimensions.Varying Re content sharply decreases the formation of MSG defects.A concentration-attached Rayleigh-Taylor instability(RTI)superheating(CARTISH)model,considering solidification shrinkage,was proposed to comprehend the formation of MSG defects.Simulation results based on this model are consistent with the experimentally observed distribution and degree of MSG defects under different conditions.Effective control of the CARTISH is critical to managing MSG defects.
文摘Loop Heat Pipe (LHP) performance strongly depends on the performance of a wick that is porous media inserted in an evaporator. In this paper, the visualization results of thermo-fluid behavior on the surface of the wick with microscopic infrared thermography were reported. In this study, 2 different samples that simulated a part of wick in the evaporator were used. The wicks were made by different two materials: polytetrafluoroethylene (PTFE) and stainless steel (SUS). The pore radii of PTFE wick and SUS wick are 1.2 μm and 22.5 μm. The difference of thermo-fluid behavior that was caused by the difference of material was investigated. These two materials include 4 different properties: pore radius, thermal conductivity, permeability and porosity. In order to investigate the effect of the thermal conductivity on wick’s operating mode, the phase diagram on the q-k<sub>eff</sub> plane was made. Based on the temperature line profiles, two operating modes: mode of heat conduction and mode of convection were observed. The effective thermal conductivity of the porous media has strong effect on the operating modes. In addition, the difference of heat leak through the wick that was caused by the difference of the material was discussed.
文摘 Microscale chemistry is appealing to all levels of education.In contrast to conventional macroscale chemistry,only minute amount of chemicals are required to undertaking a chemical investigation.……
基金the Ministry of Education, Culture, Sports, Science and Technology of Japan[Grants-in-Aid for Scientific Research Nos. 17011005, 19500716 and 21500863]
文摘 Microscale laboratory is environmentally benign as the amount of reagents,waste,energy and cost can be reduced dramatically,and exposure to potentially toxic chemicals is diminished.……
基金supported by the National Natural Science Foundation of China(No.22276219)the foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+1 种基金the major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0063).
文摘Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.
基金financially supported by the National Natural Science Foundation of China(grants 22479128,22125903,and 22439003)the National Key R&D Program of China(grant 2022YFA1504100)+3 种基金the United Foundation for Dalian Institute of Chemical Physics,Chinese Academy of Sciences,and Shenyang Institute of Automation,Chinese Academy of Sciences(DICP&SIA UN202501)the State Key Laboratory of Catalysis(no.2024SKL-A-001)the Energy Revolution S&T Program of Yulin Innovation Institute of Clean Energy(grant E412010508)the China National Postdoctoral Program for Innovative Talents(BX20240334).
文摘The rapid rise of artificial intelligence(AI)-integrated electronics,has created an urgent demand for microscale energy storage systems that are not only compact but also capable of intelligent interaction,rapid responsiveness,and seamless system-level integration.Traditional power sources struggle to meet the stringent requirements of miniaturized and multifunctional electronics,where device footprints shrink to the sub-centimeter or even millimeter scale while functionality expands toward adaptive sensing,and wireless communication.
基金supported by the National Natural Science Foundation of China(Grant Nos.12304474)Natural Science Foundation of Henan(252300421222),National Natural Science Foundation of China(Grant Nos.62477043,12247105,12474413,11935006,12421005)+3 种基金Key Research and Promotion Projects in Henan Province(232102231033)Joint Fund of Henan Province Science and Technology R&D Program(225200810071)Science and Technology Major Project of Henan Province(231100220800)The Henan Science and Technology Major Project of the Department of Science and Technology of Henan Province(241100210400).
文摘Solid-state phosphorescent materials with stimulus-responsive properties have been widely developed for diverse applications.However,the task of generating excited states with long lifetimes in aqueous solution remains challenging due to the ultrafast deactivation of the triplet excitons and the difficulty in regulating stimulation sites in an aqueous environment.Additionally,most existing materials are primarily responsive to limited stimuli,such as light,oxygen,or temperature.Here,we present a microscale rigid framework engineering strategy that can be used to modulate the phosphorescence properties of carbon nanodots(CNDs),by brightening triplet excitons through ultrasound-enhanced rigidity in CNDs.Ultrasound-responsive phosphorescent CNDs with a lifetime of 1.25 seconds in an aqueous solution were achieved.The CNDs exhibit high sensitivity to surrounding ultrasound,showing a linear response to ultrasound exposure during the treatment period.The ultrasound-responsive phosphorescent CNDs demonstrate potential applications as sensing units in ultrasound radar detection and in vivo afterglow imaging.
基金support from the University of Texas at San Antonio through a startup grantsupport from the Advanced Research Projects Agency−Energy(ARPA-E)IGNIITE program,U.S.Department of Energy,under Award No.DE-AR0001930support from the University of Alabama,Tuscaloosa through a startup grant.
文摘CONSPECTUS:Electrochemical devices are typically designed for operation over a narrow pH range and are constrained in the choice of catalysts and operating potentials by the pH environment of the electrodes.This is the result of a heretofore lack of a viable strategy to maintain pH gradients between the electrodes over practically significant time durations with only a minimal impact on the device performance.While bipolar interfaces are wellknown,they typically result in high junction potential losses that make them impractical in real-life systems.We have demonstrated a way to overcome this long-standing challenge using our tailormade,microscale bipolar interfaces,which allows the use of acidic electrolytes at one electrode and alkaline electrolytes at the other,without mixing over time.
基金support from the National University of Singapore(no.R-263-000-678-133)supported by the Spanish MINECO grants FIS2012-36113-C03-03,FIS2014-55563-REDC and FIS2015-69295-C3-1-P+2 种基金support from the National Natural Science Foundation of China(no.11504252)the Natural Science Foundation for the Youth of Jiangsu Province(no.BK20150306)the Natural Science Foundation for Colleges and Universities in Jiangsu Province of China(no.15KJB140008).
文摘Since the invention of optical tweezers,optical manipulation has advanced significantly in scientific areas such as atomic physics,optics and biological science.Especially in the past decade,numerous optical beams and nanoscale devices have been proposed to mechanically act on nanoparticles in increasingly precise,stable and flexible ways.Both the linear and angular momenta of light can be exploited to produce optical tractor beams,tweezers and optical torque from the microscale to the nanoscale.Research on optical forces helps to reveal the nature of light–matter interactions and to resolve the fundamental aspects,which require an appropriate description of momenta and the forces on objects in matter.In this review,starting from basic theories and computational approaches,we highlight the latest optical trapping configurations and their applications in bioscience,as well as recent advances down to the nanoscale.Finally,we discuss the future prospects of nanomanipulation,which has considerable potential applications in a variety of scientific fields and everyday life.
基金supported by the National Natural Science Foundation of China(Grant No.51176203)the Natural Science Foundation of Naval University of Engineering(Grant No.HGDYDJJ10011)the Natural Science Foundation for Youngsters of Naval University of Engineering(Grant No.HGDQNJJ10017)
文摘Based on constructal theory,the constructs of three"volume-point"heat conduction models with three-dimensional cylindrical element and rectangular and triangular elements on microscale and nanoscale are optimized by taking minimum entransy dissipation rate as optimization objective.The optimal constructs of the three"volume-point"heat conduction models with minimum dimensionless equivalent thermal resistance are obtained.The results show that the optimal constructs of the three-dimensional cylindrical assembly based on the minimizations of dimensionless equivalent thermal resistance and dimensionless maximum thermal resistance are different,which is obviously different from the comparison between those of the corresponding two-dimensional rectangular assembly based on the minimizations of these two objectives.The optimal constructs based on rectangular and triangular elements on microscale and nanoscale when the size effect takes effect are obviously different from those when the size effect does not take effect.Because the thermal current density in the high conductivity channel of the rectangular and triangular second order assemblies are not linear with the length,the optimal constructs of these assemblies based on the minimization of entransy dissipation rate are different from those based on the minimization of maximum temperature difference.The dimensionless equivalent thermal resistance defined based on entransy dissipation rate reflects the average heat transfer performance of the construct.The studies on"volume-point"heat conduction constructal problems at three-dimensional conditions and microscale and nanoscale by taking minimum entransy dissipation rate as optimization objective extend the application range of the entransy dissipation extremum principle.
基金supported by grants from the Special Projects for Strengthening Basic Research of Peking University(No.BMU2018JC005)the Application Research and Achievement Popularization of Clinical Characteristics in Capital from Beijing Municipal Science and Technology Commission(No.z161100000516227)。
文摘Background:Endometrial cancer is one of the most common malignancies of the reproductive system.Effective and cost-effective screening method for populations at high risk is not available.This study aimed to investigate specimen adequacy and the influencing factors in microscale endometrial sampling biopsy and to evaluate the diagnostic accuracy and medical cost of biopsy in endometrial cancer and atypical hyperplasia screenings in comparison with hysteroscopic endometrial biopsy.Methods:A total of 1551 patients at high risk for endometrial lesions who required hysteroscopic endometrial biopsy from November 2017 to August 2018 were included.Microscale endometrial sampling biopsy was performed,followed by hysteroscopic endometrial biopsy.We evaluated the specimen adequacy and influencing factors of microscale endometrial sampling.Diagnostic consistency between microscale endometrial sampling biopsy and hysteroscopic endometrial biopsy was evaluated.The sensitivity,specificity,positive predictive value,and negative predictive value of microscale endometrial sampling biopsy in screening for endometrial cancer and atypical hyperplasia were analyzed,and the medical costs of the two procedures were compared.Results:The specimen adequacy was 81.2%.Patient age,menopausal status,endometrial thickness,and endometrial lesion type were correlated with specimen adequacy.There was good consistency in distinguishing benign and malignant endometrial diseases between microscale endometrial sampling biopsy and hysteroscopic biopsy(kappa 0.950,95%CI 0.925-0.975).The sensitivity,specificity,positive predictive value,and negative predictive value of microscale endometrial sampling biopsy were 91.7%,100.0%,100.0%,and 99.3%for endometrial cancer screening,respectively,and 82.0%,100.0%,100.0%,and 99.4%for atypical hyperplasia screening.The medical cost of endometrial sampling biopsy was only 22.1%of the cost of hysteroscopic biopsy.Conclusions:Microscale endometrial sampling biopsy is a minimally invasive alternative technique for obtaining adequate endometrial specimens for histopathological examination.It has the potential to be used in detecting endometrial cancer and atypical hyperplasia with high efficiency and low cost.
