The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence...The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence is still lacking.To validate this framework,here we employ a programmable robotic platform,where a single light-controlled wheeled robot travels in an activity landscape.Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force.This result unambiguously confirms the theoretical predictions,thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter.展开更多
Interparticle frictional interactions are ubiquitous in colloidal systems,exerting a profound influence on their structural and physical attributes.In this study,we employed Brownian dynamics simulations to explore th...Interparticle frictional interactions are ubiquitous in colloidal systems,exerting a profound influence on their structural and physical attributes.In this study,we employed Brownian dynamics simulations to explore the non-equilibrium dynamics in colloidal systems,focusing particularly on the role of tangential friction and its influence on the macroscopic physical properties of colloids.We found that the disruption of instantaneous time-reversal symmetry by tangential frictional interactions can trigger the self-assembly of colloidal systems into intricate network configurations,and these novel structures exhibit unique depletion force and rheological properties that set them apart from traditional colloidal gel systems.These findings not only help deepen our comprehension of the self-assembly phenomena in non-equilibrium colloidal systems but also offer fresh insights for the development of colloidal materials with tailored characteristics.展开更多
We conduct optical-tweezers experiments to investigate the average potential energies of passive plates harmonically trapped in bacterial suspensions.Our results show that the mean potential energies along both the ma...We conduct optical-tweezers experiments to investigate the average potential energies of passive plates harmonically trapped in bacterial suspensions.Our results show that the mean potential energies along both the major and minor axes increase with bacterial concentration but decrease with trap stiffness.Notably,the average potential energy along the major axis consistently exceeds that along the minor axis.This discrepancy from equilibrium systems is primarily attributed to the distinct bacterial flow fields and direct bacterium–plate collisions near the major and minor axes,as evidenced by the higher orientational order around the plate along the major compared to the minor axis,despite identical bacterial densities in these regions.Our findings highlight the critical role of hydrodynamic interactions in determining the potential energy of passive objects immersed in an active bath.展开更多
By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanop...By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM） and vibrating sample magnetometer （VSM）, respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation （10 kGy） is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation （10 kGy） are mainly in small cubic shape and the size uniformity of these particles is good.展开更多
We quantify the mean potential energy of a passive colloidal particle harmonically confined in a bacterial solution using optical traps.We find that the average potential energy of the passive particle depends on the ...We quantify the mean potential energy of a passive colloidal particle harmonically confined in a bacterial solution using optical traps.We find that the average potential energy of the passive particle depends on the trap stiffness,in contrast to the equilibrium case where energy partition is independent of the external constraints.The constraint dependence of the mean potential energy originates from the fact that the persistent collisions between the passive particle and the active bacteria are influenced by the particle relaxation dynamics.Our experimental results are consistent with the Brownian dynamics simulations,and confirm the recent theoretical prediction.展开更多
An active system consisting of many self-spinning dimers is simulated, and a distinct local rotational jamming transition is observed as the density increases. In the low density regime, the system stays in an absorbi...An active system consisting of many self-spinning dimers is simulated, and a distinct local rotational jamming transition is observed as the density increases. In the low density regime, the system stays in an absorbing state,in which each dimer rotates independently subject to the applied torque;while in the high density regime,a fraction of the dimers become rotationally jammed into local clusters, and the system exhibits microphaseseparation like two-phase morphologies. For high enough densities, the system becomes completely jammed in both rotational and translational degrees of freedom. Such a simple system is found to exhibit rich and multiscale disordered hyperuniformities among the above phases: the absorbing state shows a critical hyperuniformity of the strongest class and subcritically preserves the vanishing density fluctuation scaling up to some length scale;the locally jammed state shows a two-phase hyperuniformity conversely beyond some length scale with respect to the phase cluster sizes;the totally jammed state appears to be a monomer crystal, but intrinsically loses large-scale hyperuniformity. These results are inspiring for designing novel phase-separation and disordered hyperuniform systems through dynamical organization.展开更多
Brownian motors and self-phoretic microswimmers are two typical micromotors,for which thermal fluctuations play different roles.Brownian motors utilize thermal noise to acquire unidirectional motion,while thermal fluc...Brownian motors and self-phoretic microswimmers are two typical micromotors,for which thermal fluctuations play different roles.Brownian motors utilize thermal noise to acquire unidirectional motion,while thermal fluctuations randomize the self-propulsion of self-phoretic microswimmers.Here we perform mesoscale simulations to study a composite micromotor composed of a self-thermophoretic Janus particle under a time-modulated external ratchet potential.The composite motor exhibits a unidirectional transport,whose direction can be reversed by tuning the modulation frequency of the external potential.The maximum transport capability is close to the superposition of the drift speed of the pure Brownian motor and the self-propelling speed of the pure self-thermophoretic particle.Moreover,the hydrodynamic effect influences the orientation of the Janus particle in the ratched potential,hence also the performance of the composite motor.Our work thus provides an enlightening attempt to actively exploit inevitable thermal fluctuations in the implementation of the self-phoretic microswimmers.展开更多
Diffusion of colloidal particles in microchannels has been extensively investigated,where the channel wall is either a no-slip or a slip-passive boundary.However,in the context of active fluids,driving boundary walls ...Diffusion of colloidal particles in microchannels has been extensively investigated,where the channel wall is either a no-slip or a slip-passive boundary.However,in the context of active fluids,driving boundary walls are ubiquitous and are expected to have a substantial effect on the particle dynamics.By mesoscale simulations,we study the diffusion of a chemically active colloidal particle in composite channels,which are constructed by alternately arranging the no-slip and diffusio-osmotic boundary walls.In this case,the chemical reaction catalyzed by the active colloidal particle creates a local chemical gradient along the channel wall,which drives a diffusio-osmotic flow parallel to the wall.We show that the diffusio-osmotic flow can significantly change the spatial distribution and diffusion dynamics of the colloidal particle in the composite channels.By modulating the surface properties of the channel wall,we can achieve different patterns of colloidal position distribution.The findings thus propose a novel possibility to manipulate colloidal diffusion in microfluidics,and highlight the importance of driving boundary walls in dynamics of colloidal particles in microchannels.展开更多
Thermophoresis and diffusiophoresis respectively refer to the directed drift of suspended particles in solutions with external thermal and chemical gradients, which have been widely used in the manipulation of mesosco...Thermophoresis and diffusiophoresis respectively refer to the directed drift of suspended particles in solutions with external thermal and chemical gradients, which have been widely used in the manipulation of mesoscopic particles. We here study a phoretic-like motion of a passive colloidal particle immersed in inhomogeneous active baths, where the thermal and chemical gradients are replaced separately by activity and concentration gradients of the active particles. By performing simulations, we show that the passive colloidal particle experiences phoretic-like forces that originate from its interactions with the inhomogeneous active fluid, and thus drifts along the gradient field, leading to an accumulation. The results are similar to the traditional phoretic effects occurring in passive colloidal suspensions, implying that the concepts of thermophoresis and diffusiophoresis could be generalized into active baths.展开更多
Topological edge flow and dissipationless odd viscosity are two remarkable features of chiral active fluids composed of active spinners.These features can significantly influence the dynamics of suspended passive part...Topological edge flow and dissipationless odd viscosity are two remarkable features of chiral active fluids composed of active spinners.These features can significantly influence the dynamics of suspended passive particles and the interactions between the particles.By computer simulations,we investigate the transport phenomenon of anisotropic passive objects and the self-assembly behavior of passive spherical particles in the active spinner fluid.It is found that in confined systems,nonspherical passive objects can stably cling to boundary walls and are unidirectionally and robustly transported by edge flow of spinners.Furthermore,in an unconfined system,passive spherical particles are able to form stable clusters that spontaneously and unidirectionally rotate as a whole.In these phenomena,strong particle-wall and interparticle effective attractions play a vital role,which originate from spinner-mediated depletion-like interactions and can be largely enhanced by odd viscosity of spinner fluids.Our results thus provide new insight into the robust transport of cargoes and the nonequilibrium self-assembly of passive intruders.展开更多
Due to the breaking of time-reversal and parity symmetries and the presence of non-conservative microscopic interactions,active spinner fluids and solids respectively exhibit nondissipative odd viscosity and nonstorag...Due to the breaking of time-reversal and parity symmetries and the presence of non-conservative microscopic interactions,active spinner fluids and solids respectively exhibit nondissipative odd viscosity and nonstorage odd elasticity,engendering phenomena unattainable in traditional passive or active systems.Here,we study the effects of odd viscosity and elasticity on phase behaviors of active spinner systems.We find the spinner fluid under a simple shear experiences an anisotropic gas-liquid phase separation driven by the odd-viscosity stress.This phase separation exhibits equilibrium-like behavior,with both binodal-like and spinodal curves and critical point.However,the formed dense liquid phase is unstable,since the odd elasticity instantly takes over the odd viscosity to condense the liquid into a solid-like phase.The unusual phase behavior essentially arises from the competition between thermal fluctuations and the odd response-induced effective attraction.Our results demonstrate that the cooperation of odd viscosity and elasticity can lead to exotic phase behavior,revealing their fundamental roles in phase transition.展开更多
The interaction between cell surface receptors and extracellular ligands is highly related to many physiological processes in living systems.Many techniques have been developed to measure the ligand-receptor binding k...The interaction between cell surface receptors and extracellular ligands is highly related to many physiological processes in living systems.Many techniques have been developed to measure the ligand-receptor binding kinetics at the single-cell level.However,few techniques can measure the physiologically relevant shear binding affinity over a single cell in the clinical environment.Here,we develop a new optical technique,termed single-cell rotational adhesion frequency assay(scRAFA),that mimics in vivo cell adhesion to achieve label-free determination of both homogeneous and heterogeneous binding kinetics of targeted cells at the subcellular level.Moreover,the scRAFA is also applicable to analyze the binding affinities on a single cell in native human biofluids.With its superior performance and general applicability,scRAFA is expected to find applications in study of the spatial organization of cell surface receptors and diagnosis of infectious diseases.展开更多
Understanding and controlling phase separation in nonequilibrium colloidal systems are of both fundamental and applied importance.In this article,we investigate the spatiotemporal control of phase separation in chemic...Understanding and controlling phase separation in nonequilibrium colloidal systems are of both fundamental and applied importance.In this article,we investigate the spatiotemporal control of phase separation in chemically active immotile colloids.We show that a population of silver colloids can spontaneously phase separate into dense clusters in hydrogen peroxide(H_(2)O_(2))due to phoretic attraction.The characteristic length of the formed pattern was quantified and monitored over time,revealing a growth and coarsening phase with different growth kinetics.By tuning the trigger frequency of light,the lengths and growth kinetics of the clusters formed by silver colloids in H_(2)O_(2)can be controlled.In addition,structured light was used to precisely control the shape,size,and contour of the phase-separated patterns.This study provides insight into the microscopic details of the phase separation of chemically active colloids induced by phoretic attraction,and presents a generic strategy for controlling the spatiotemporal evolution of the resulting mesoscopic patterns.展开更多
Mixtures of active self-propelled and passive colloidal particles promise rich assembly and dynamic states that are beyond reach via equilibrium routes.Yet,controllable transition between different dynamic states rema...Mixtures of active self-propelled and passive colloidal particles promise rich assembly and dynamic states that are beyond reach via equilibrium routes.Yet,controllable transition between different dynamic states remains rare.Here,we reveal a plethora of dynamic behaviors emerging in assemblies of chemically propelled snowman-like active colloids and passive spherical particles as the particle shape,size,and composition are tuned.For example,assembles of one or more active colloids with one passive particle exhibit distinct translating or orbiting states while those composed of one active colloid with 2 passive particles display persistent“8”-like cyclic motion or hopping between circling states around one passive particle in the plane and around the waist of 2 passive ones out of the plane,controlled by the shape of the active colloid and the size of the passive particles,respectively.These morphology-tailored dynamic transitions are in excellent agreement with state diagrams predicted by mesoscale dynamics simulations.Our work discloses new dynamic states and corresponding transition strategies,which promise new applications of active systems such as micromachines with functions that are otherwise impossible.展开更多
Using colloidal particles with different thermosensitivities,we observe the transition from a crystalline solid to a dis-ordered glass by tuning the size mismatch of the constituent particles in quasi-two-dimensional c...Using colloidal particles with different thermosensitivities,we observe the transition from a crystalline solid to a dis-ordered glass by tuning the size mismatch of the constituent particles in quasi-two-dimensional configurations.The transition is clearly identifiable by the correlation functions of the orientational order parameters and its susceptibilities.Different from typical order-to-disorder transitions such as melting,where the underlying mechanism involves the diffusion of defects,the disordered phase in the crystal-to-glass transition grows via a nucleation process.The disordered clusters grow in size as the particle mismatch increases,and eventually percolate the whole system,which signifies the qualitative change from an ordered crystal to a disordered glass.展开更多
Active matter refers to systems composed of individual units that consume locally stored energy to generate mechanical motion.Examples of active matter include biological entities such as schools of fish,flocks of bir...Active matter refers to systems composed of individual units that consume locally stored energy to generate mechanical motion.Examples of active matter include biological entities such as schools of fish,flocks of birds,bacterial colonies,and synthetic systems such as self-propelled colloidal particles and engineered nanobots.The study of active matter seeks to provide understanding for complex behaviors and emergent phenomena arising from interactions of these energy-consuming units,with implications for fields ranging from physics and biology to materials science and robotics.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.T2325027,12274448,T2350007,12404239,12174041,12325405,12090054,and T2221001)the National Key R&D Program of China (Grant No.2022YFF0503504)。
文摘The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence is still lacking.To validate this framework,here we employ a programmable robotic platform,where a single light-controlled wheeled robot travels in an activity landscape.Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force.This result unambiguously confirms the theoretical predictions,thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter.
基金the support of the National Natural Science Foundation of China(Grant Nos.12274448,12325405,and 12174390)the National Key R&D Program of China(Grant No.2022YFF0503504)。
文摘Interparticle frictional interactions are ubiquitous in colloidal systems,exerting a profound influence on their structural and physical attributes.In this study,we employed Brownian dynamics simulations to explore the non-equilibrium dynamics in colloidal systems,focusing particularly on the role of tangential friction and its influence on the macroscopic physical properties of colloids.We found that the disruption of instantaneous time-reversal symmetry by tangential frictional interactions can trigger the self-assembly of colloidal systems into intricate network configurations,and these novel structures exhibit unique depletion force and rheological properties that set them apart from traditional colloidal gel systems.These findings not only help deepen our comprehension of the self-assembly phenomena in non-equilibrium colloidal systems but also offer fresh insights for the development of colloidal materials with tailored characteristics.
基金supports of the National Natural Science Foundation of China(Grant Nos.12304245,12374205,12475031,and 12364029)the Science Foundation of China University of Petroleum,Beijing(Grant Nos.2462023YJRC031 and 2462024BJRC010)+4 种基金the National Key Laboratory of Petroleum Resources and Engineering(Grant No.PRE/DX-2407)the Natural Science Foundation of Shandong Province(Grant No.ZR2024YQ017)the Young Elite Scientist Sponsorship Program by BAST(Grant No.BYESS2023300)the Beijing Institute of Technology Research Fund Program for Young ScholarsThis work was also supported by Beijing National Laboratory for Condensed Matter Physics(Grant Nos.2023BNLCMPKF014 and 2024BNLCMPKF009).
文摘We conduct optical-tweezers experiments to investigate the average potential energies of passive plates harmonically trapped in bacterial suspensions.Our results show that the mean potential energies along both the major and minor axes increase with bacterial concentration but decrease with trap stiffness.Notably,the average potential energy along the major axis consistently exceeds that along the minor axis.This discrepancy from equilibrium systems is primarily attributed to the distinct bacterial flow fields and direct bacterium–plate collisions near the major and minor axes,as evidenced by the higher orientational order around the plate along the major compared to the minor axis,despite identical bacterial densities in these regions.Our findings highlight the critical role of hydrodynamic interactions in determining the potential energy of passive objects immersed in an active bath.
基金This work was supported by the Natural Science Foundation of Henan Province under grant No. 0611023900.
文摘By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM） and vibrating sample magnetometer （VSM）, respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation （10 kGy） is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation （10 kGy） are mainly in small cubic shape and the size uniformity of these particles is good.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874397,11674365,11774393,and 11774394).
文摘We quantify the mean potential energy of a passive colloidal particle harmonically confined in a bacterial solution using optical traps.We find that the average potential energy of the passive particle depends on the trap stiffness,in contrast to the equilibrium case where energy partition is independent of the external constraints.The constraint dependence of the mean potential energy originates from the fact that the persistent collisions between the passive particle and the active bacteria are influenced by the particle relaxation dynamics.Our experimental results are consistent with the Brownian dynamics simulations,and confirm the recent theoretical prediction.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11774393, 11404378, 12274448, 22272040, and T2325027)Youth Innovation Promotion Association of CAS (Grant No. 2017014)the National Key R&D Program of China (Grant Nos. 2022YFF0503504 and 2022YFA1203200)。
文摘An active system consisting of many self-spinning dimers is simulated, and a distinct local rotational jamming transition is observed as the density increases. In the low density regime, the system stays in an absorbing state,in which each dimer rotates independently subject to the applied torque;while in the high density regime,a fraction of the dimers become rotationally jammed into local clusters, and the system exhibits microphaseseparation like two-phase morphologies. For high enough densities, the system becomes completely jammed in both rotational and translational degrees of freedom. Such a simple system is found to exhibit rich and multiscale disordered hyperuniformities among the above phases: the absorbing state shows a critical hyperuniformity of the strongest class and subcritically preserves the vanishing density fluctuation scaling up to some length scale;the locally jammed state shows a two-phase hyperuniformity conversely beyond some length scale with respect to the phase cluster sizes;the totally jammed state appears to be a monomer crystal, but intrinsically loses large-scale hyperuniformity. These results are inspiring for designing novel phase-separation and disordered hyperuniform systems through dynamical organization.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874397 and 11674365).
文摘Brownian motors and self-phoretic microswimmers are two typical micromotors,for which thermal fluctuations play different roles.Brownian motors utilize thermal noise to acquire unidirectional motion,while thermal fluctuations randomize the self-propulsion of self-phoretic microswimmers.Here we perform mesoscale simulations to study a composite micromotor composed of a self-thermophoretic Janus particle under a time-modulated external ratchet potential.The composite motor exhibits a unidirectional transport,whose direction can be reversed by tuning the modulation frequency of the external potential.The maximum transport capability is close to the superposition of the drift speed of the pure Brownian motor and the self-propelling speed of the pure self-thermophoretic particle.Moreover,the hydrodynamic effect influences the orientation of the Janus particle in the ratched potential,hence also the performance of the composite motor.Our work thus provides an enlightening attempt to actively exploit inevitable thermal fluctuations in the implementation of the self-phoretic microswimmers.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874397,11674365,and 11774393)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)。
文摘Diffusion of colloidal particles in microchannels has been extensively investigated,where the channel wall is either a no-slip or a slip-passive boundary.However,in the context of active fluids,driving boundary walls are ubiquitous and are expected to have a substantial effect on the particle dynamics.By mesoscale simulations,we study the diffusion of a chemically active colloidal particle in composite channels,which are constructed by alternately arranging the no-slip and diffusio-osmotic boundary walls.In this case,the chemical reaction catalyzed by the active colloidal particle creates a local chemical gradient along the channel wall,which drives a diffusio-osmotic flow parallel to the wall.We show that the diffusio-osmotic flow can significantly change the spatial distribution and diffusion dynamics of the colloidal particle in the composite channels.By modulating the surface properties of the channel wall,we can achieve different patterns of colloidal position distribution.The findings thus propose a novel possibility to manipulate colloidal diffusion in microfluidics,and highlight the importance of driving boundary walls in dynamics of colloidal particles in microchannels.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11874397)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB33000000)。
文摘Thermophoresis and diffusiophoresis respectively refer to the directed drift of suspended particles in solutions with external thermal and chemical gradients, which have been widely used in the manipulation of mesoscopic particles. We here study a phoretic-like motion of a passive colloidal particle immersed in inhomogeneous active baths, where the thermal and chemical gradients are replaced separately by activity and concentration gradients of the active particles. By performing simulations, we show that the passive colloidal particle experiences phoretic-like forces that originate from its interactions with the inhomogeneous active fluid, and thus drifts along the gradient field, leading to an accumulation. The results are similar to the traditional phoretic effects occurring in passive colloidal suspensions, implying that the concepts of thermophoresis and diffusiophoresis could be generalized into active baths.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11874397,11774393,11774394,and 11974044)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33030300)。
文摘Topological edge flow and dissipationless odd viscosity are two remarkable features of chiral active fluids composed of active spinners.These features can significantly influence the dynamics of suspended passive particles and the interactions between the particles.By computer simulations,we investigate the transport phenomenon of anisotropic passive objects and the self-assembly behavior of passive spherical particles in the active spinner fluid.It is found that in confined systems,nonspherical passive objects can stably cling to boundary walls and are unidirectionally and robustly transported by edge flow of spinners.Furthermore,in an unconfined system,passive spherical particles are able to form stable clusters that spontaneously and unidirectionally rotate as a whole.In these phenomena,strong particle-wall and interparticle effective attractions play a vital role,which originate from spinner-mediated depletion-like interactions and can be largely enhanced by odd viscosity of spinner fluids.Our results thus provide new insight into the robust transport of cargoes and the nonequilibrium self-assembly of passive intruders.
基金the support of the National Natural Science Foundation of China(Nos.T2325027,12274448,12325405,and 12174390)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB33000000).
文摘Due to the breaking of time-reversal and parity symmetries and the presence of non-conservative microscopic interactions,active spinner fluids and solids respectively exhibit nondissipative odd viscosity and nonstorage odd elasticity,engendering phenomena unattainable in traditional passive or active systems.Here,we study the effects of odd viscosity and elasticity on phase behaviors of active spinner systems.We find the spinner fluid under a simple shear experiences an anisotropic gas-liquid phase separation driven by the odd-viscosity stress.This phase separation exhibits equilibrium-like behavior,with both binodal-like and spinodal curves and critical point.However,the formed dense liquid phase is unstable,since the odd elasticity instantly takes over the odd viscosity to condense the liquid into a solid-like phase.The unusual phase behavior essentially arises from the competition between thermal fluctuations and the odd response-induced effective attraction.Our results demonstrate that the cooperation of odd viscosity and elasticity can lead to exotic phase behavior,revealing their fundamental roles in phase transition.
基金Y.L.,H.D.,J.L.and Y.Z.acknowledge the financial support of National Institute of General Medical Sciences of the National Institutes of Health.(DP2GM128446)National Science Foundation(ECCS-2001650)X.L.,M.Y.acknowledge the financial support of National Natural Science Foundation of China(No.11874397).
文摘The interaction between cell surface receptors and extracellular ligands is highly related to many physiological processes in living systems.Many techniques have been developed to measure the ligand-receptor binding kinetics at the single-cell level.However,few techniques can measure the physiologically relevant shear binding affinity over a single cell in the clinical environment.Here,we develop a new optical technique,termed single-cell rotational adhesion frequency assay(scRAFA),that mimics in vivo cell adhesion to achieve label-free determination of both homogeneous and heterogeneous binding kinetics of targeted cells at the subcellular level.Moreover,the scRAFA is also applicable to analyze the binding affinities on a single cell in native human biofluids.With its superior performance and general applicability,scRAFA is expected to find applications in study of the spatial organization of cell surface receptors and diagnosis of infectious diseases.
基金supported by the Shenzhen Science and Technology Program(RCYX20210609103122038 and JCYJ20210324121408022)the National Natural Science Foundation of China(T2322006,T2325027,12274448,12225410 and 12074243)
文摘Understanding and controlling phase separation in nonequilibrium colloidal systems are of both fundamental and applied importance.In this article,we investigate the spatiotemporal control of phase separation in chemically active immotile colloids.We show that a population of silver colloids can spontaneously phase separate into dense clusters in hydrogen peroxide(H_(2)O_(2))due to phoretic attraction.The characteristic length of the formed pattern was quantified and monitored over time,revealing a growth and coarsening phase with different growth kinetics.By tuning the trigger frequency of light,the lengths and growth kinetics of the clusters formed by silver colloids in H_(2)O_(2)can be controlled.In addition,structured light was used to precisely control the shape,size,and contour of the phase-separated patterns.This study provides insight into the microscopic details of the phase separation of chemically active colloids induced by phoretic attraction,and presents a generic strategy for controlling the spatiotemporal evolution of the resulting mesoscopic patterns.
基金the Natural Science Foundation of Guangdong Province(Project No.2022A1515011800)the Science and Technology Innovation Commission of Shenzhen(JCYJ20220531103205012)+2 种基金the Key Project of Guangdong Provincial Department of Education(2023ZDZX3021)M.Y.acknowledges the support of the National Natural Science Foundation of China(Nos.12274448 and T2325027)the National Key R&D Program of China(No.2022YFF0503504).
文摘Mixtures of active self-propelled and passive colloidal particles promise rich assembly and dynamic states that are beyond reach via equilibrium routes.Yet,controllable transition between different dynamic states remains rare.Here,we reveal a plethora of dynamic behaviors emerging in assemblies of chemically propelled snowman-like active colloids and passive spherical particles as the particle shape,size,and composition are tuned.For example,assembles of one or more active colloids with one passive particle exhibit distinct translating or orbiting states while those composed of one active colloid with 2 passive particles display persistent“8”-like cyclic motion or hopping between circling states around one passive particle in the plane and around the waist of 2 passive ones out of the plane,controlled by the shape of the active colloid and the size of the passive particles,respectively.These morphology-tailored dynamic transitions are in excellent agreement with state diagrams predicted by mesoscale dynamics simulations.Our work discloses new dynamic states and corresponding transition strategies,which promise new applications of active systems such as micromachines with functions that are otherwise impossible.
基金supported by the National Natural Science Foundation of China(11874395 and 12174434)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB3300000).|。
文摘Using colloidal particles with different thermosensitivities,we observe the transition from a crystalline solid to a dis-ordered glass by tuning the size mismatch of the constituent particles in quasi-two-dimensional configurations.The transition is clearly identifiable by the correlation functions of the orientational order parameters and its susceptibilities.Different from typical order-to-disorder transitions such as melting,where the underlying mechanism involves the diffusion of defects,the disordered phase in the crystal-to-glass transition grows via a nucleation process.The disordered clusters grow in size as the particle mismatch increases,and eventually percolate the whole system,which signifies the qualitative change from an ordered crystal to a disordered glass.
文摘Active matter refers to systems composed of individual units that consume locally stored energy to generate mechanical motion.Examples of active matter include biological entities such as schools of fish,flocks of birds,bacterial colonies,and synthetic systems such as self-propelled colloidal particles and engineered nanobots.The study of active matter seeks to provide understanding for complex behaviors and emergent phenomena arising from interactions of these energy-consuming units,with implications for fields ranging from physics and biology to materials science and robotics.
