Ultrabright femtosecond X-ray pulses generated by X-ray free-electron lasers(XFELs)enable the high-resolution determination of nanoparticle structures without crystallization or freezing.As each particle that interact...Ultrabright femtosecond X-ray pulses generated by X-ray free-electron lasers(XFELs)enable the high-resolution determination of nanoparticle structures without crystallization or freezing.As each particle that interacts with the pulse is destroyed,an aerodynamic lens(ADL)is used to update the particles by focusing them into a narrow beam in real time.Current single-particle imaging(SPI)experiments are limited by an insufficient number of diffraction patterns;therefore,optimized ADLs are required to improve the hit rate and signal-to-noise ratio,particularly for small particles.Herein,an efficient and simple method for designing ADLs and a new ADL specifically designed for SPI using this method are presented.A new method is proposed based on the functional relationship between a key parameter and its influencing parameters in the ADL,which is established through theoretical analysis and numerical simulations.A detailed design process for the new ADL is also introduced.Both simulations and experiments are performed to characterize the behavior of the particles in the ADL.The results show that particles with diameters ranging from 30 to 500 nm can be effectively focused into a narrow beam.In particular,particles smaller than 100 nm exhibit better performance at lower flow rates than the injector currently used in SPI.The new ADL increases the beam density and reduces the gas background noise.This new method facilitates the design of ADLs for SPI and has potential applications in other fields that utilize focused aerosol beams.展开更多
Modern chromatography is increasingly focused on miniaturization and integration. Compared to conventional liquid chromatography, microfluidic chip liquid chromatography(microchip-LC) has the potential due to its zero...Modern chromatography is increasingly focused on miniaturization and integration. Compared to conventional liquid chromatography, microfluidic chip liquid chromatography(microchip-LC) has the potential due to its zero-dead volume connection and ease of integration. Nano-sized packings have the potential to significantly enhance separation performance in microchip-LC. However, their application has been hindered by packing difficulties. This study presents a method for packing nano-sized silica particles into a microchannel as the stationary phase. The microchip-LC packed column was prepared by combining the weir and the porous silica single-particle as frit to retain the packing particles. A surface tensionbased single-particle picking technique was established to insert porous single-particle frit into glass microchannels. Additionally, we developed a slurry packing method that utilizes air pressure to inject nano-sized packing into the microchannel. Pressure-driven chromatographic separation was performed using this nano-packed column integrated into a glass microchip. The mixture of four PAHs was successfully separated within just 8 min using a 5 mm separation channel length, achieving high theoretical plates(10~6plates/m). Overall, these findings demonstrate the potential of utilizing nano-sized packings for enhancing chromatographic performance in microchip systems.展开更多
In the present study,the nanofliud natural convection is investigated by the energy-conserving dissipative particle dynamics(eDPD)method,where the nanoparticles are considered at the single-particle level.The thermal ...In the present study,the nanofliud natural convection is investigated by the energy-conserving dissipative particle dynamics(eDPD)method,where the nanoparticles are considered at the single-particle level.The thermal expansion coefficientβand the viscosityμof the simulated system containing nanoparticles are calculated and found to be in close alignment with the previous simulation results.The single-particle hydrodynamics in e DPD enables simulations of nanofluid natural convection with higher Rayleigh numbers and greater nanoparticle volume fractions.Additionally,this approach is utilized to simulate the nanoparticle distribution during the enhanced heat transfer process in the nanofluid natural convection.The localized aggregation of nanoparticles enhances the heat transfer performance of the nanofluid under specific Rayleigh numbers and nanoparticles volume fractions.展开更多
Under hydrothermal environment,we synthesized lanthanide ions doped sodium yttrium fluoride(NaYF4:Er,Tm@NaYF4:Ce,Tb) luminescent microcrystals via an epitaxial growth technique.The structure and morphology of these mi...Under hydrothermal environment,we synthesized lanthanide ions doped sodium yttrium fluoride(NaYF4:Er,Tm@NaYF4:Ce,Tb) luminescent microcrystals via an epitaxial growth technique.The structure and morphology of these microcrystals were examined by SEM,TEM,EDS and XRD measurements.These particles show dual-mode emissions with red upconversion(UC) and green down conversion(DC) as single particles level.The mean length and diameter of these microparticles increase from 0.43 to2.26 μm and from 1.33 to 1.86 μm,respectively.Most interestingly,the photoluminescence properties of NaYF4:Er,Tm@NaYF4:Ce,Tb phosphor crystals are highly dependent on the crystallite size.The microcrystals fluoresce emit dual-mode emissions when they are solid or dispersed in solvents.Benefiting its intensive fluorescence and uniform morphology,these materials hold great potential for security and anti-counterfeiting applications.展开更多
Carbon dots(CDs), because of their unique properties, are being rapidly developed as important luminescent materials for imaging, sensing, and use in photonic devices. However, most of the reported fundamental propert...Carbon dots(CDs), because of their unique properties, are being rapidly developed as important luminescent materials for imaging, sensing, and use in photonic devices. However, most of the reported fundamental properties of the CDs are results of investigations conducted in the solution state, which may be completely different from those conducted in the solid state. In this work, we study the luminescence properties, photostability, and the dynamics of CDs in different matrix environments, from ensemble to the single-particle level. We observed that the properties associated with the emission centers and photostability of CDs were extremely sensitive to the local chemical environment. A better understanding of the dependence of the spectroscopic properties of CDs on the complex local chemical environment is an important step toward finding new ways of controlling the optical properties of CDs and optimizing their use in various applications.展开更多
Single-particle resonances in the continuum are crucial for studies of exotic nuclei.In this study,the Green’s function approach is employed to search for single-particle resonances based on the relativistic-mean-fie...Single-particle resonances in the continuum are crucial for studies of exotic nuclei.In this study,the Green’s function approach is employed to search for single-particle resonances based on the relativistic-mean-field model.Taking^(120)Sn as an example,we identify singleparticle resonances and determine the energies and widths directly by probing the extrema of the Green’s functions.In contrast to the results found by exploring for the extremum of the density of states proposed in our recent study[Chin.Phys.C,44:084105(2020)],which has proven to be very successful,the same resonances as well as very close energies and widths are obtained.By comparing the Green’s functions plotted in different coordinate space sizes,we also found that the results very slightly depend on the space size.These findings demonstrate that the approach by exploring for the extremum of the Green’s function is also very reliable and effective for identifying resonant states,regardless of whether they are wide or narrow.展开更多
The observation of single-particle surface-enhanced Raman scattering(SERS) has generated considerable interest both in the nanomaterials filed and in the single-particle spectroscopy community.It is a challenge to rea...The observation of single-particle surface-enhanced Raman scattering(SERS) has generated considerable interest both in the nanomaterials filed and in the single-particle spectroscopy community.It is a challenge to realize rapid,facile,and high throughput SERS at single nanoparticle level.Here,without the complex experimental device and difficult experimental operations,a general single-particle SERS technique has been achieved by using dark-field-assisted surface-enhanced Raman spectroscopy(DFSERS).This advanced method provides in-situ characterization of the chemical reaction performance at single gold nanorod.展开更多
Real-time exploring the cellular endocytic pathway of viral capsid proteins(VCPs)functionalized nanocargos at the single-particle level can provide deep insight into the kinetic information involved in virus infection...Real-time exploring the cellular endocytic pathway of viral capsid proteins(VCPs)functionalized nanocargos at the single-particle level can provide deep insight into the kinetic information involved in virus infection.In this work,porcine circovirus type 2(PCV2)VCPs with different functions are modified onto the surface of upconversion nanoparticles(VCPs-UCNPs)to investigate the cellular internalization process in real-time.Clathrin-mediated endocytosis is found to be the essential uptake mechanism for these VCPs-UCNPs.Besides,it is verified that P_(1)-UCNPs(PCV2 VCPs with nuclear localization signal,namely P1)can be easily assembled close to the perinuclear area,which is different from that of P_(2)-UCNPs(PCV2 VCPs without nuclear localization signal,namely P_(2)).Interestingly,multistep entry processes are observed.Particularly,confined diffusion is observed during the transmembrane process.The intracellular transport of VCPs-UCNPs is dependent on microtubules toward the cell interior.During this process,P_(1)-UCNPs display increased velocities with active transport,while diffusion much faster around the perinuclear area.But for P_(2)-UCNPs,there are only two phases involved in their endocytosis process.This study presents distinct dynamic mechanisms for the nanocargos with different functions,which would make a useful contribution to the development of robust drug delivery systems.展开更多
Single-particle microbeam is uniquely capable of precisely delivering a preset number of charged particles to individual cells or sub-cellular targets to be determined in vitro, It is crucial to find a reference point...Single-particle microbeam is uniquely capable of precisely delivering a preset number of charged particles to individual cells or sub-cellular targets to be determined in vitro, It is crucial to find a reference point that relates the microbeam＇s location to the microscope＇s plane, and align individual targets at this reference point for cell irradiation. To choose an appropriate reference point, an approach based on analysing the intensity distribution of fluorescence in a thin scintillator excited by traversing particles is newly developed using the CAS-LIBB single-particle microbeam, which features decisive physical signification and sufficient resolution. As its bonus, this on-line analysis provides precise and fast response to the determination of beam profile and potentially optimizes the microbeam quality by further adjusting hardware setup.展开更多
The Experiments, methods and results of obtaining micron beam in the Microbeam Facility of the Institute of Plasma Physics were discussed in this paper. The H+2 beam was accelerated by the Van de GraafF electrostatic ...The Experiments, methods and results of obtaining micron beam in the Microbeam Facility of the Institute of Plasma Physics were discussed in this paper. The H+2 beam was accelerated by the Van de GraafF electrostatic accelerator, and the collimator at the end of the beam line is a 60 μm thick stainless steel chip. And as a result, particle tracks on the solid track probes (CR39 film) etched in the solution of NaOH showed that the beam can go through the collimator with a small aperure (2000, 300, 55, 30, or 10 μm) and 3.5 μm thick vacuum film (Mylar). Besides the CR39 method, the beam was measured by an energy spectrum detector after the 10 μm diameter aperture and the 3.5 μm thick vacuum film too.展开更多
Single-particle microbeam as a powerful tool can open a research field to find answers to many enigmas in radiobiology. A single-particle microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioen...Single-particle microbeam as a powerful tool can open a research field to find answers to many enigmas in radiobiology. A single-particle microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering （LIBB）, Chinese Academy of Sciences （CAS）, China. However there has been less research activities in this field concerning the original process of the interaction between low-energy ions and complicated organisms. To address this challenge, an in situ multi-dimensional quantitative fluorescence microscopy system combined with the CAS-LIBB single-particle microbeam II endstation is proposed. In this article, the rationale, logistics and development of many aspects of the proposed system are discussed.展开更多
The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.T...The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.展开更多
We study the level structures of N = 7 - 9 isotones and their mirror nuclei in the framework of the single-particle potential model. Considering the limitation of the conventional potential-model calculation, the isos...We study the level structures of N = 7 - 9 isotones and their mirror nuclei in the framework of the single-particle potential model. Considering the limitation of the conventional potential-model calculation, the isospindependent 12 coupling is newly introduced in the average potential. The modified model gives a unified description for the structures of all studied nuclei. Galculations self-consistently produce the s-d level inversion in N = 9 isotones and their mirror nuclei. Meanwhile, the s-p level inversion in the mirror nuclei ^11Be and ^11N is reproduced. The study confirms the neutron halo structures in ^11Be（2s1/2）, ^11Be（1p1/2）, ^12B（2s1/2）, ^14B（2s1/2）, ^13C（2sl/2）, ^15C（2s1/2） and the proton halo structure in ^17F（2s1/2）. The agreement between theory and experiment indicates that the inclusion of the i2 coupling is a feasible way to explain the abnormal structures of exotic light nuclei.展开更多
The proposed multi-dimensional quantitative fluorescence microscopy for the CASLIBB single-particle microbeam II endstation is a CCD-based imaging system. We systematically analyse the theoretical and the practical co...The proposed multi-dimensional quantitative fluorescence microscopy for the CASLIBB single-particle microbeam II endstation is a CCD-based imaging system. We systematically analyse the theoretical and the practical considerations pertinent to choosing the right CCD camera and unveiling the principles underlying multifarious parameters. Therefore, this analysis can be a valuable tool in scrutinizing each parameter and clarifying proper usage of a scientific CCD camera.展开更多
Planar assemblies of plasmonic nanoparticles have provided opportunities in various fields.This study exploits the self-assembly of gold nanorods(AuNRs)into planar,layered chiral superstructures(dodecamer)using DNA or...Planar assemblies of plasmonic nanoparticles have provided opportunities in various fields.This study exploits the self-assembly of gold nanorods(AuNRs)into planar,layered chiral superstructures(dodecamer)using DNA origami technology.Due to the collective plasmonic coupling modes,the dodecamers exhibit g-factors of up to+0.06,which is 4-5 times higher than those of the dextrodimers.The chiroptical property of the superstructures proved to be strongly size-dependent,exhibiting enhanced g-factors with increasing the size of AuNRs.Moreover,by excluding the averaging and close-to-racemic effects in the ensemble colloids,circular differential scattering(CDS)and circularly polarized luminescence(CPL)were studied at the single-particle level,revealing the essential role of the structural chirality of superstructure in correlating single-particle scattering with nearby dye emission.The observed correlated CDS and CPL show g-factors up to−0.17 and−0.6,respectively.These results highlight the potential of DNA origami-directed plasmonic assemblies for nanoscale chirality engineering,with applications in biosensing,chiral photonics,and metamaterials.展开更多
Facet-dependent semiconductor photocatalysts exhibit immense potential in solar energy conversion and environmental purification.Variations in composition,morphology,atomic arrangement,and surface defects among differ...Facet-dependent semiconductor photocatalysts exhibit immense potential in solar energy conversion and environmental purification.Variations in composition,morphology,atomic arrangement,and surface defects among different nanomaterials result in significant diversities in photocatalytic activities.Nevertheless,the structural diversity covered by integrity and uniformity is detrimental to highlighting the relationship between material and activity,compromising the logical design and optimization of photocatalysts.Fortunately,the“temporally-spatially”resolved single-particle fluorescence spectroscopy imaging technique paves the way for an in-depth exploration of facet-dependent carrier separation and transfer processes at different sites of single nanoparticle,thus providing a profound understanding of the photocatalytic reaction mechanism.In this review,we briefly introduce the imaging principle of single-particle fluorescence spectroscopy.Subsequently,we focus on the recent advancements in single-particle fluorescence spectroscopy technology to characterize the structural complexity and heterogeneity of facetdependent semiconductor photocatalysts,as well as its application in revealing the interfacial interactions between catalysts and reactants.Finally,we provide outlooks on the development prospects of single-particle fluorescence spectroscopy in the field of photocatalysis.展开更多
Understanding the mechanisms of degradation in lead halide perovskite nanocrystals is critical for their future application in optoelectronic devices.We report single-particle measurements of the photoluminescence fro...Understanding the mechanisms of degradation in lead halide perovskite nanocrystals is critical for their future application in optoelectronic devices.We report single-particle measurements of the photoluminescence from cesium lead bromide nanocrystals coated with a silica shell(CsPbBr_(3)@SiO_(2)).Through correlative imaging,we quantified changes in the fluorescence intensity trajectories of the same nanocrystals before and after annealing them at different temperatures.We observe that nearly equal numbers of CsPbBr_(3)@SiO_(2) nanocrystals exhibit an increase versus decrease in the amount of time they spend in an emissive state after annealing at temperatures of 70 and 100℃.On the other hand,annealing at 120℃ produces a decrease in the on-fraction for most nanocrystals and,correspondingly,a substantial decrease in the photoluminescence intensity for a thin film annealed at this temperature.We attribute the differences in behavior among individual nanocrystals to heterogeneity in the distribution of trap states that are initially present.X-ray photoelectron,time-resolved photoluminescence,and transient absorption spectroscopies performed on thin films of CsPbBr_(3)@SiO_(2) nanocrystals indicate that thermal annealing heals electron traps by passivating surface Pb ions and simultaneously creates hole traps through the formation of Pb and Cs vacancies.The relative rates of these parallel processes depend on the annealing temperature,which are important to account for when developing passivation strategies for lead halide perovskite nanocrystals in optoelectronic devices that will operate at elevated temperatures.展开更多
The plasma membrane is a sophisticated,organized,and highly heterogeneous structure that compartmentalizes cellular processes.To decipher the biological processes involving membrane proteins,it is necessary to analyze...The plasma membrane is a sophisticated,organized,and highly heterogeneous structure that compartmentalizes cellular processes.To decipher the biological processes involving membrane proteins,it is necessary to analyze their spatiotemporal dynamics.However,it is difficult to directly assess the dynamics and interactions of biomolecules in living cells using traditional biochemical methods.Singleparticle tracking (SPT)methods for imaging and tracking single particles conjugated with fluorescent probes offer an ideal approach to acquire valuable and complementary information about dynamic intracellular processes.SPT can be used to quantitatively monitor the diverse motions of individual particles in living cells.SPT also provides super-spatiotemporal resolution that allows early-stage or rapid response information to be obtained for a better understanding of molecular basis of associated signal transduction processes.More importantly,SPT can be used to detect the motion paths of individual biomolecules in vivo and in situ,thus unveiling the dynamic behavior of the biomolecules that support developmental processes in living cells.In this review,we give an overview of SPT methods,from image acquisition to the detection of single particles,as well as tracking and data analysis.We also discuss recent applications of SPT methods in the field ofplant biology to reveal the complex biological functions of membrane proteins.展开更多
Lipid-based nanomedicines(LBNMs),including liposomes,lipid nanoparticles(LNPs)and extracellular vesicles(EVs),are recognized as one of the most clinically acceptable nano-formulations.However,the bench-to-bedside tran...Lipid-based nanomedicines(LBNMs),including liposomes,lipid nanoparticles(LNPs)and extracellular vesicles(EVs),are recognized as one of the most clinically acceptable nano-formulations.However,the bench-to-bedside translation efficiency is far from satisfactory,mainly due to the lack of in-depth understanding of their physical and biochemical attributes at the single-particle level.In this review,we first give a brief introduction of LBNMs,highlighting some milestones and related scientific and clinical achievements in the past several decades,as well as the grand challenges in the characterization of LBNMs.Next,we present an overview of each category of LB-NMs as well as the core properties that largely dictate their biological characteristics and clinical performance,such as size distribution,particle concentration,morphology,drug encapsulation and surface properties.Then,the recent applications of several analytical techniques including electron microscopy,atomic force microscopy,fluorescence microscopy,Raman microscopy,nanoparticle tracking analysis,tunable resistive pulse sensing and flow cytometry on the single-particle characterization of LBNMs are thoroughly discussed.Particularly,the com-parative advantages of the newly developed nano-flow cytometry that enables quantitative analysis of both the physical and biochemical characteristics of LBNMs smaller than 40 nm with high throughput and statistical ro-bustness are emphasized.The overall aim of this review article is to illustrate the importance,challenges and achievements associated with single-particle characterization of LBNMs.展开更多
The positive-parity single-neutron levels in an axially-deformed relativistic quadrupole Woods-Saxon potential are analyzed. Neutron states are obtained as the solutions of the corresponding single-particle Dirac equa...The positive-parity single-neutron levels in an axially-deformed relativistic quadrupole Woods-Saxon potential are analyzed. Neutron states are obtained as the solutions of the corresponding single-particle Dirac equation, using the coupled-channels method in the coordinate space. The evolution of the levels close to the continuum threshold and, in particular, the occurrence of singleneutron resonant states as the functions of the axial deformation parameter 0 β 0.5, are examined using the eigenphase representation. Calculations are performed for different values of the radius of the potential (R/r 0 ) 3 , corresponding to a variation of the mass number A.展开更多
基金supported by the Major State Basic Research Development Program of China(No.2022YFA1603703)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB 37040303)+1 种基金National Natural Science Foundation of China(No.12335020)Shanghai Soft X-ray Free Electron Laser Facility beamline project.
文摘Ultrabright femtosecond X-ray pulses generated by X-ray free-electron lasers(XFELs)enable the high-resolution determination of nanoparticle structures without crystallization or freezing.As each particle that interacts with the pulse is destroyed,an aerodynamic lens(ADL)is used to update the particles by focusing them into a narrow beam in real time.Current single-particle imaging(SPI)experiments are limited by an insufficient number of diffraction patterns;therefore,optimized ADLs are required to improve the hit rate and signal-to-noise ratio,particularly for small particles.Herein,an efficient and simple method for designing ADLs and a new ADL specifically designed for SPI using this method are presented.A new method is proposed based on the functional relationship between a key parameter and its influencing parameters in the ADL,which is established through theoretical analysis and numerical simulations.A detailed design process for the new ADL is also introduced.Both simulations and experiments are performed to characterize the behavior of the particles in the ADL.The results show that particles with diameters ranging from 30 to 500 nm can be effectively focused into a narrow beam.In particular,particles smaller than 100 nm exhibit better performance at lower flow rates than the injector currently used in SPI.The new ADL increases the beam density and reduces the gas background noise.This new method facilitates the design of ADLs for SPI and has potential applications in other fields that utilize focused aerosol beams.
基金supported by the National Natural Science Foundation of China (No.21936001)the Beijing Outstanding Young Scientist Program (No.BJJWZYJH01201910005017)。
文摘Modern chromatography is increasingly focused on miniaturization and integration. Compared to conventional liquid chromatography, microfluidic chip liquid chromatography(microchip-LC) has the potential due to its zero-dead volume connection and ease of integration. Nano-sized packings have the potential to significantly enhance separation performance in microchip-LC. However, their application has been hindered by packing difficulties. This study presents a method for packing nano-sized silica particles into a microchannel as the stationary phase. The microchip-LC packed column was prepared by combining the weir and the porous silica single-particle as frit to retain the packing particles. A surface tensionbased single-particle picking technique was established to insert porous single-particle frit into glass microchannels. Additionally, we developed a slurry packing method that utilizes air pressure to inject nano-sized packing into the microchannel. Pressure-driven chromatographic separation was performed using this nano-packed column integrated into a glass microchip. The mixture of four PAHs was successfully separated within just 8 min using a 5 mm separation channel length, achieving high theoretical plates(10~6plates/m). Overall, these findings demonstrate the potential of utilizing nano-sized packings for enhancing chromatographic performance in microchip systems.
基金Project supported by the National Natural Science Foundation of China(Nos.11872283 and 2002212)the Sailing Program of Shanghai,China(No.20YF1432800)。
文摘In the present study,the nanofliud natural convection is investigated by the energy-conserving dissipative particle dynamics(eDPD)method,where the nanoparticles are considered at the single-particle level.The thermal expansion coefficientβand the viscosityμof the simulated system containing nanoparticles are calculated and found to be in close alignment with the previous simulation results.The single-particle hydrodynamics in e DPD enables simulations of nanofluid natural convection with higher Rayleigh numbers and greater nanoparticle volume fractions.Additionally,this approach is utilized to simulate the nanoparticle distribution during the enhanced heat transfer process in the nanofluid natural convection.The localized aggregation of nanoparticles enhances the heat transfer performance of the nanofluid under specific Rayleigh numbers and nanoparticles volume fractions.
基金Project supported by the National Natural Science Foundation of China (21271074,51372091)the Teamwork Projects funded by the Guangdong Natural Science Foundation (S2013030012842)+1 种基金Guangdong Provincial Science&Technology Project (2015B090903074)Guangzhou Science&Technology Project (201605030005)。
文摘Under hydrothermal environment,we synthesized lanthanide ions doped sodium yttrium fluoride(NaYF4:Er,Tm@NaYF4:Ce,Tb) luminescent microcrystals via an epitaxial growth technique.The structure and morphology of these microcrystals were examined by SEM,TEM,EDS and XRD measurements.These particles show dual-mode emissions with red upconversion(UC) and green down conversion(DC) as single particles level.The mean length and diameter of these microparticles increase from 0.43 to2.26 μm and from 1.33 to 1.86 μm,respectively.Most interestingly,the photoluminescence properties of NaYF4:Er,Tm@NaYF4:Ce,Tb phosphor crystals are highly dependent on the crystallite size.The microcrystals fluoresce emit dual-mode emissions when they are solid or dispersed in solvents.Benefiting its intensive fluorescence and uniform morphology,these materials hold great potential for security and anti-counterfeiting applications.
基金financial support from National Natural Science Foundation of China (No.22073046)Fundamental Research Funds for the Central Universities。
文摘Carbon dots(CDs), because of their unique properties, are being rapidly developed as important luminescent materials for imaging, sensing, and use in photonic devices. However, most of the reported fundamental properties of the CDs are results of investigations conducted in the solution state, which may be completely different from those conducted in the solid state. In this work, we study the luminescence properties, photostability, and the dynamics of CDs in different matrix environments, from ensemble to the single-particle level. We observed that the properties associated with the emission centers and photostability of CDs were extremely sensitive to the local chemical environment. A better understanding of the dependence of the spectroscopic properties of CDs on the complex local chemical environment is an important step toward finding new ways of controlling the optical properties of CDs and optimizing their use in various applications.
基金supported by the National Natural Science Foundation of China(No.U2032141)the Natural Science Foundation of Henan Province(No.202300410479,No.202300410480)+1 种基金the Foundation of Fundamental Research for Young Teachers of Zhengzhou University(No.JC202041041)the Physics Research and Development Program of Zhengzhou University(No.32410217).
文摘Single-particle resonances in the continuum are crucial for studies of exotic nuclei.In this study,the Green’s function approach is employed to search for single-particle resonances based on the relativistic-mean-field model.Taking^(120)Sn as an example,we identify singleparticle resonances and determine the energies and widths directly by probing the extrema of the Green’s functions.In contrast to the results found by exploring for the extremum of the density of states proposed in our recent study[Chin.Phys.C,44:084105(2020)],which has proven to be very successful,the same resonances as well as very close energies and widths are obtained.By comparing the Green’s functions plotted in different coordinate space sizes,we also found that the results very slightly depend on the space size.These findings demonstrate that the approach by exploring for the extremum of the Green’s function is also very reliable and effective for identifying resonant states,regardless of whether they are wide or narrow.
基金supported by the National Natural Science Foundation of China(Nos.21421004,21834001)sponsored by National Ten Thousand Talent Program for young top-notch talent。
文摘The observation of single-particle surface-enhanced Raman scattering(SERS) has generated considerable interest both in the nanomaterials filed and in the single-particle spectroscopy community.It is a challenge to realize rapid,facile,and high throughput SERS at single nanoparticle level.Here,without the complex experimental device and difficult experimental operations,a general single-particle SERS technique has been achieved by using dark-field-assisted surface-enhanced Raman spectroscopy(DFSERS).This advanced method provides in-situ characterization of the chemical reaction performance at single gold nanorod.
基金financial support from the National Natural Science Foundation of China(Nos.22174079,21974073).
文摘Real-time exploring the cellular endocytic pathway of viral capsid proteins(VCPs)functionalized nanocargos at the single-particle level can provide deep insight into the kinetic information involved in virus infection.In this work,porcine circovirus type 2(PCV2)VCPs with different functions are modified onto the surface of upconversion nanoparticles(VCPs-UCNPs)to investigate the cellular internalization process in real-time.Clathrin-mediated endocytosis is found to be the essential uptake mechanism for these VCPs-UCNPs.Besides,it is verified that P_(1)-UCNPs(PCV2 VCPs with nuclear localization signal,namely P1)can be easily assembled close to the perinuclear area,which is different from that of P_(2)-UCNPs(PCV2 VCPs without nuclear localization signal,namely P_(2)).Interestingly,multistep entry processes are observed.Particularly,confined diffusion is observed during the transmembrane process.The intracellular transport of VCPs-UCNPs is dependent on microtubules toward the cell interior.During this process,P_(1)-UCNPs display increased velocities with active transport,while diffusion much faster around the perinuclear area.But for P_(2)-UCNPs,there are only two phases involved in their endocytosis process.This study presents distinct dynamic mechanisms for the nanocargos with different functions,which would make a useful contribution to the development of robust drug delivery systems.
文摘Single-particle microbeam is uniquely capable of precisely delivering a preset number of charged particles to individual cells or sub-cellular targets to be determined in vitro, It is crucial to find a reference point that relates the microbeam＇s location to the microscope＇s plane, and align individual targets at this reference point for cell irradiation. To choose an appropriate reference point, an approach based on analysing the intensity distribution of fluorescence in a thin scintillator excited by traversing particles is newly developed using the CAS-LIBB single-particle microbeam, which features decisive physical signification and sufficient resolution. As its bonus, this on-line analysis provides precise and fast response to the determination of beam profile and potentially optimizes the microbeam quality by further adjusting hardware setup.
基金The project supported by the National Science Foundation of in Anhui Province,China(No.01046201)
文摘The Experiments, methods and results of obtaining micron beam in the Microbeam Facility of the Institute of Plasma Physics were discussed in this paper. The H+2 beam was accelerated by the Van de GraafF electrostatic accelerator, and the collimator at the end of the beam line is a 60 μm thick stainless steel chip. And as a result, particle tracks on the solid track probes (CR39 film) etched in the solution of NaOH showed that the beam can go through the collimator with a small aperure (2000, 300, 55, 30, or 10 μm) and 3.5 μm thick vacuum film (Mylar). Besides the CR39 method, the beam was measured by an energy spectrum detector after the 10 μm diameter aperture and the 3.5 μm thick vacuum film too.
文摘Single-particle microbeam as a powerful tool can open a research field to find answers to many enigmas in radiobiology. A single-particle microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering （LIBB）, Chinese Academy of Sciences （CAS）, China. However there has been less research activities in this field concerning the original process of the interaction between low-energy ions and complicated organisms. To address this challenge, an in situ multi-dimensional quantitative fluorescence microscopy system combined with the CAS-LIBB single-particle microbeam II endstation is proposed. In this article, the rationale, logistics and development of many aspects of the proposed system are discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60501019,10775139 and 60971073)
文摘The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.
基金National Natural Science Foundation of China under Grant Nos.10535010 and 10775068the State Key Basic Research Program under Grant No.2007CB815004+1 种基金the CAS Knowledge Innovation Project under Grant No.KJCX2-SW-N02the Research Fund of High Education under Grant No.20010284036
文摘We study the level structures of N = 7 - 9 isotones and their mirror nuclei in the framework of the single-particle potential model. Considering the limitation of the conventional potential-model calculation, the isospindependent 12 coupling is newly introduced in the average potential. The modified model gives a unified description for the structures of all studied nuclei. Galculations self-consistently produce the s-d level inversion in N = 9 isotones and their mirror nuclei. Meanwhile, the s-p level inversion in the mirror nuclei ^11Be and ^11N is reproduced. The study confirms the neutron halo structures in ^11Be（2s1/2）, ^11Be（1p1/2）, ^12B（2s1/2）, ^14B（2s1/2）, ^13C（2sl/2）, ^15C（2s1/2） and the proton halo structure in ^17F（2s1/2）. The agreement between theory and experiment indicates that the inclusion of the i2 coupling is a feasible way to explain the abnormal structures of exotic light nuclei.
基金supported by the the National Major Technologies R&D Programme of China during the 10th Five-Year Plan Period(No.2001BA302B)the National Science Foundation for Distinguished Young Scholars(No.10225526)+1 种基金the Knowledge Innovation Programme of the Chinese Academy of Sciences(No.KSCX2-SW-324)the Foundation for University Key Teacher by the Ministry of Education(No.2005jq1135).
文摘The proposed multi-dimensional quantitative fluorescence microscopy for the CASLIBB single-particle microbeam II endstation is a CCD-based imaging system. We systematically analyse the theoretical and the practical considerations pertinent to choosing the right CCD camera and unveiling the principles underlying multifarious parameters. Therefore, this analysis can be a valuable tool in scrutinizing each parameter and clarifying proper usage of a scientific CCD camera.
基金the financial support from the National Key Research and Development Program of China(No.2021YFA1200300)the National Natural Science Foundation of China(Nos.22372031 and 22074102).
文摘Planar assemblies of plasmonic nanoparticles have provided opportunities in various fields.This study exploits the self-assembly of gold nanorods(AuNRs)into planar,layered chiral superstructures(dodecamer)using DNA origami technology.Due to the collective plasmonic coupling modes,the dodecamers exhibit g-factors of up to+0.06,which is 4-5 times higher than those of the dextrodimers.The chiroptical property of the superstructures proved to be strongly size-dependent,exhibiting enhanced g-factors with increasing the size of AuNRs.Moreover,by excluding the averaging and close-to-racemic effects in the ensemble colloids,circular differential scattering(CDS)and circularly polarized luminescence(CPL)were studied at the single-particle level,revealing the essential role of the structural chirality of superstructure in correlating single-particle scattering with nearby dye emission.The observed correlated CDS and CPL show g-factors up to−0.17 and−0.6,respectively.These results highlight the potential of DNA origami-directed plasmonic assemblies for nanoscale chirality engineering,with applications in biosensing,chiral photonics,and metamaterials.
基金supported by the National Natural Science Foundation of China(22222202,U23A20136,22072072)the Natural Science Foundation of Shandong Province(ZR2021JQ06)+2 种基金the National Key Research and Development Program of China(2020YFA0710301)the Shandong University Multidisciplinary Research and Innovation Team of Young Scholars(2020QNQT11,2020QNQT012)the Outstanding Young Scholars Projects of Shandong University。
文摘Facet-dependent semiconductor photocatalysts exhibit immense potential in solar energy conversion and environmental purification.Variations in composition,morphology,atomic arrangement,and surface defects among different nanomaterials result in significant diversities in photocatalytic activities.Nevertheless,the structural diversity covered by integrity and uniformity is detrimental to highlighting the relationship between material and activity,compromising the logical design and optimization of photocatalysts.Fortunately,the“temporally-spatially”resolved single-particle fluorescence spectroscopy imaging technique paves the way for an in-depth exploration of facet-dependent carrier separation and transfer processes at different sites of single nanoparticle,thus providing a profound understanding of the photocatalytic reaction mechanism.In this review,we briefly introduce the imaging principle of single-particle fluorescence spectroscopy.Subsequently,we focus on the recent advancements in single-particle fluorescence spectroscopy technology to characterize the structural complexity and heterogeneity of facetdependent semiconductor photocatalysts,as well as its application in revealing the interfacial interactions between catalysts and reactants.Finally,we provide outlooks on the development prospects of single-particle fluorescence spectroscopy in the field of photocatalysis.
基金supported by the National Science Foundation(NSF)under grant No.CHE-1753344 to B.S.and grant No.DMR-1905751 to R.A.L.D.M.N.acknowledges the Center for Solar Energy and Energy Storage at the McKelvey School of Engineering at Washington University in Saint Louis for financial support.performed at the Institute of Materials Science&Engineering at Washington University.X-ray diffraction was performed in the Department of Earth,Environmental,and Planetary Sciences at Washington University.
文摘Understanding the mechanisms of degradation in lead halide perovskite nanocrystals is critical for their future application in optoelectronic devices.We report single-particle measurements of the photoluminescence from cesium lead bromide nanocrystals coated with a silica shell(CsPbBr_(3)@SiO_(2)).Through correlative imaging,we quantified changes in the fluorescence intensity trajectories of the same nanocrystals before and after annealing them at different temperatures.We observe that nearly equal numbers of CsPbBr_(3)@SiO_(2) nanocrystals exhibit an increase versus decrease in the amount of time they spend in an emissive state after annealing at temperatures of 70 and 100℃.On the other hand,annealing at 120℃ produces a decrease in the on-fraction for most nanocrystals and,correspondingly,a substantial decrease in the photoluminescence intensity for a thin film annealed at this temperature.We attribute the differences in behavior among individual nanocrystals to heterogeneity in the distribution of trap states that are initially present.X-ray photoelectron,time-resolved photoluminescence,and transient absorption spectroscopies performed on thin films of CsPbBr_(3)@SiO_(2) nanocrystals indicate that thermal annealing heals electron traps by passivating surface Pb ions and simultaneously creates hole traps through the formation of Pb and Cs vacancies.The relative rates of these parallel processes depend on the annealing temperature,which are important to account for when developing passivation strategies for lead halide perovskite nanocrystals in optoelectronic devices that will operate at elevated temperatures.
基金the National Natural Science Foundation of China (31622005,31530084) the Programme of Introducing Talents of Discipline to Universities (111project,B13007).
文摘The plasma membrane is a sophisticated,organized,and highly heterogeneous structure that compartmentalizes cellular processes.To decipher the biological processes involving membrane proteins,it is necessary to analyze their spatiotemporal dynamics.However,it is difficult to directly assess the dynamics and interactions of biomolecules in living cells using traditional biochemical methods.Singleparticle tracking (SPT)methods for imaging and tracking single particles conjugated with fluorescent probes offer an ideal approach to acquire valuable and complementary information about dynamic intracellular processes.SPT can be used to quantitatively monitor the diverse motions of individual particles in living cells.SPT also provides super-spatiotemporal resolution that allows early-stage or rapid response information to be obtained for a better understanding of molecular basis of associated signal transduction processes.More importantly,SPT can be used to detect the motion paths of individual biomolecules in vivo and in situ,thus unveiling the dynamic behavior of the biomolecules that support developmental processes in living cells.In this review,we give an overview of SPT methods,from image acquisition to the detection of single particles,as well as tracking and data analysis.We also discuss recent applications of SPT methods in the field ofplant biology to reveal the complex biological functions of membrane proteins.
基金We are grateful to the National Natural Science Foundation of China(21934004,21627811)the National Key R&D Program of China(2021YFA0909400)the Natural Science Foundation of Fujian Province(2022J01329)for financial support.
文摘Lipid-based nanomedicines(LBNMs),including liposomes,lipid nanoparticles(LNPs)and extracellular vesicles(EVs),are recognized as one of the most clinically acceptable nano-formulations.However,the bench-to-bedside translation efficiency is far from satisfactory,mainly due to the lack of in-depth understanding of their physical and biochemical attributes at the single-particle level.In this review,we first give a brief introduction of LBNMs,highlighting some milestones and related scientific and clinical achievements in the past several decades,as well as the grand challenges in the characterization of LBNMs.Next,we present an overview of each category of LB-NMs as well as the core properties that largely dictate their biological characteristics and clinical performance,such as size distribution,particle concentration,morphology,drug encapsulation and surface properties.Then,the recent applications of several analytical techniques including electron microscopy,atomic force microscopy,fluorescence microscopy,Raman microscopy,nanoparticle tracking analysis,tunable resistive pulse sensing and flow cytometry on the single-particle characterization of LBNMs are thoroughly discussed.Particularly,the com-parative advantages of the newly developed nano-flow cytometry that enables quantitative analysis of both the physical and biochemical characteristics of LBNMs smaller than 40 nm with high throughput and statistical ro-bustness are emphasized.The overall aim of this review article is to illustrate the importance,challenges and achievements associated with single-particle characterization of LBNMs.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10775004 and 10975008)the Major State 973Program (Grant No. 2007CB815000)
文摘The positive-parity single-neutron levels in an axially-deformed relativistic quadrupole Woods-Saxon potential are analyzed. Neutron states are obtained as the solutions of the corresponding single-particle Dirac equation, using the coupled-channels method in the coordinate space. The evolution of the levels close to the continuum threshold and, in particular, the occurrence of singleneutron resonant states as the functions of the axial deformation parameter 0 β 0.5, are examined using the eigenphase representation. Calculations are performed for different values of the radius of the potential (R/r 0 ) 3 , corresponding to a variation of the mass number A.
