Surface particles growing in large aperture optical element （LAOE） have significant impact on LAOE＇s stable operation. It is a challenge for the online system to inspect the particles with long working distance, en...Surface particles growing in large aperture optical element （LAOE） have significant impact on LAOE＇s stable operation. It is a challenge for the online system to inspect the particles with long working distance, enough precision and high efficiency because of the system constraints. In this paper, an effective and portable inspection instrument is designed based on dark-field imaging principle. A Nikon lens and an industrial high definition （HD） camera are selected to construct the vision system to inspect particles of microns size spreading over hundreds of millimeters. Using two motors and other mechanical structure, the system can realize auto-focus and image rectification functions. The line light sources are installed on both sides of the LAOE in a sealed box while the vision system is portable and working outside the box. An adaptive binarization method is proposed to process the captured dark-field image. The distribution of particles on the LAOE＇s surface is investigated. Because of the high resolution of the captured image, the SSE2 instructions optimization method is used to reduce the time cost of the algorithm. Experiments show that the instrument can inspect LAOE effectively and accurately.展开更多
Real-time monitoring of reaction processes is helpful for understanding the reaction mechanisms. In this study we investigated the etching mechanism of gold nanopartides （AuNPs） by iodine on a single-nanopartide lev...Real-time monitoring of reaction processes is helpful for understanding the reaction mechanisms. In this study we investigated the etching mechanism of gold nanopartides （AuNPs） by iodine on a single-nanopartide level because AuNPs have become important nanoprobes with applications in sensing and bioimaging fields owing to their specific localized surface plasmon resonance （LSPR） properties. By using a scattered-light dark-field microscopic imaging （iDFM） technique, the in situ KI/I2-treated etching processes of various shapes of AuNPs, including nanospheres （AuNSs）, nanorods （AuNRs）, and nanotrigonal prisms （AuNTs）, were monitored in real time. It was found that the scattered light of the different shapes of AuNPs exhibited noticeable color changes upon exposure to the etching solution. The scattering spectra during the etching process showed obvious blue-shifts with decreasing scattered intensity owing to the oxidation of Au atoms into [AuI2]-. Both finite-difference time-domain （FDTD） simulations and monitoring of morphological variations proved that the etching was a thermodynamic-dependent process through a chamfering mechanism coupled with layer-by-layer peeling, resulting in isotropic spheres with decreased particle sizes.展开更多
Fabrication of high-quality optics puts a strong demand on high-throughput detection of macroscopic bulk defects in optical components.A dark-field line confocal imaging method is proposed with two distinct advantage...Fabrication of high-quality optics puts a strong demand on high-throughput detection of macroscopic bulk defects in optical components.A dark-field line confocal imaging method is proposed with two distinct advantages:(ⅰ)a point-to-line confocal scheme formed by a columnar elliptical mirror and an optical fiber bundle breaks through the constraint on light collection angle and field of view in the traditional line confocal microscopy using an objective,allowing for an extended confocal line field of more than 100 mm while maintaining a light collection angle of 27°;(ⅱ)the bulk defects are independently illuminated as a function of time to eliminate the cross talk in the direction of the confocal slit,thus preserving point confocality and showing the optical section thicknesses to be 162μm in the axial direction,and 19 and 22μm in the orthogonal transverse directions.The experimental results verify that the method has a minimum detectable bulk defect of less than 5μm and an imaging efficiency of 400 mm2/s.The method shows great potential in high-throughput and highsensitivity bulk defects detection.展开更多
Single scattering particles,especially noble metal(plasmonic) nanoparticles,based analytical techniques are attractive recently and becoming the research focus of the light scattering analytical techniques.In this min...Single scattering particles,especially noble metal(plasmonic) nanoparticles,based analytical techniques are attractive recently and becoming the research focus of the light scattering analytical techniques.In this mini review,we summarize the single scattering particles based analytical techniques in the past decade including single scattering particles counting,single plasmonic nanoparticles sensing,and single plasmonic nanoparticles tracking/imaging.We emphasize the discussion on the single plasmonic nanoparticles sensing that combines with dark-field microscopy and resonant Rayleigh scattering spectroscopy.展开更多
Background The benefits of early use of norepinephrine in endotoxemic shock remain unknown.We aimed to elucidate the effects of different doses of norepinephrine in early-stage endotoxemic shock using a clinically rel...Background The benefits of early use of norepinephrine in endotoxemic shock remain unknown.We aimed to elucidate the effects of different doses of norepinephrine in early-stage endotoxemic shock using a clinically relevant large animal model.Methods Vasodilatory shock was induced by endotoxin bolus in 30 Bama suckling pigs.Treatment included fluid resuscitation and administration of different doses of norepinephrine,to induce return to baseline mean arterial pressure(MAP).Fluid management,hemodynamic,microcirculation,inflammation,and organ function variables were monitored.All animals were supported for 6 h after endotoxemic shock.Results Infused fluid volume decreased with increasing norepinephrine dose.Return to baseline MAP was achieved more frequently with doses of 0.8µg/kg/min and 1.6µg/kg/min(P<0.01).At the end of the shock resuscitation period,cardiac index was higher in pigs treated with 0.8µg/kg/min norepinephrine(P<0.01),while systemic vascular resistance was higher in those receiving 0.4µg/kg/min(P<0.01).Extravascular lung water level and degree of organ edema were higher in animals administered no or 0.2µg/kg/min norepinephrine(P<0.01),while the percentage of perfused small vessel density(PSVD)was higher in those receiving 0.8µg/kg/min(P<0.05)and serum lactate was higher in the groups administered no and 1.6µg/kg/min norepinephrine(P<0.01).Conclusions The impact of norepinephrine on the macro-and micro-circulation in early-stage endotoxemic shock is dose-dependent,with very low and very high doses resulting in detrimental effects.Only an appropriate norepinephrine dose was associated with improved tissue perfusion and organ function.展开更多
X-ray dark-field imaging using a grating interferometer has shown potential benefits for a variety of applications in recent years.X-ray dark-field image is commonly retrieved by using discrete Fourier transform from ...X-ray dark-field imaging using a grating interferometer has shown potential benefits for a variety of applications in recent years.X-ray dark-field image is commonly retrieved by using discrete Fourier transform from the acquired phasestepping data.The retrieval process assumes a constant phase step size and a constant flux for each stepped grating position.However,stepping errors and flux fluctuations inevitably occur due to external vibrations and/or thermal drift during data acquisition.Previous studies have shown that those influences introduce errors in the acquired phase-stepping data,which cause obvious moiréartifacts in the retrieved refraction image.This work investigates moiréartifacts in x-ray dark-field imaging as a result of flux fluctuations.For the retrieved mean intensity,amplitude,visibility and dark-field images,the dependence of moiréartifacts on flux fluctuation factors is theoretically derived respectively by using a first-order Taylor series expansion.Results of synchrotron radiation experiments verify the validity of the derived analytical formulas.The spatial frequency characteristics of moiréartifacts are analyzed and compared to those induced by phase-stepping errors.It illustrates that moiréartifacts can be estimated by a weighted mean of flux fluctuation factors,with the weighting factors dependent on the moiréphase and different greatly for each retrieved image.Furthermore,moiréartifacts can even be affected by object’s features not displayed in the particular contrast.These results can be used to interpret images correctly,identify sources of moiréartifacts,and develop dedicated algorithms to remove moiréartifacts in the retrieved multi-contrast images.展开更多
Integrating discrete plasmonic nanoparticles into assemblies can induce plasmonic coupling that produces collective plasmonic properties,which are not available for single nanoparticles.Theoretical analysis revealed t...Integrating discrete plasmonic nanoparticles into assemblies can induce plasmonic coupling that produces collective plasmonic properties,which are not available for single nanoparticles.Theoretical analysis revealed that plasmonic coupling derived from assemblies could produce stronger electromagnetic field enhancement effects.Thus,plasmonic assemblies enable better performance in plasmon-based applications,such as enhanced fluorescence and Raman effects.This makes them hold great potential for trace analyte detection and nanomedicine.Herein,we focus on the recent advances in various plasmonic nanoassembles such as dimers,tetramers,and core-satellite structures,and discuss their applications in biosensing and cell imaging.The fabrication strategies for self-assembled plasmonic nanostructures are described,including top-down strategies,self-assembly methods linked by DNA,ligand,polymer,amino acid,or proteins,and chemical overgrowth methods.Thereafter,their applications in biosensor and cell imaging based on dark-field imaging,surface-enhanced Raman scattering,plasmonic circular dichroism,and fluorescence imaging are discussed.Finally,the remaining challenges and prospects are elucidated.展开更多
Magnesium-lithium alloys with high lithium content have been attracting significant attention because of their low density,high formability and corrosion resistance.These properties are dependent on the distribution o...Magnesium-lithium alloys with high lithium content have been attracting significant attention because of their low density,high formability and corrosion resistance.These properties are dependent on the distribution of lithium,which is difficult to map in the presence of magnesium.In this work,a ratio spectrum-imaging method with electron energy-loss spectroscopy(EELS)is demonstrated,which enables the mapping of lithium.In application to LAZ941(Mg-9Li-4Al-1Zn in wt.%),this technique revealed that a key precipitate in the microstructure,previously thought by some to be Mg_(17)Al_(12),is in fact rich in lithium.This result was corroborated with a structural investigation by high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),showing this phase to be Al_(1-x)Zn_(x)Li,with x<<1.This work indicates the potential offered by this technique for mapping lithium in materials.展开更多
In recent years, modern optical processing technologies, such as single point diamond turning, ion beam etching, and magneto-theological finishing, arc getting break- throughs. Machining precisions of super-smooth opt...In recent years, modern optical processing technologies, such as single point diamond turning, ion beam etching, and magneto-theological finishing, arc getting break- throughs. Machining precisions of super-smooth optics have also been significantly improved. However, with increasing demands for the optical surface quality,展开更多
With the discovery and further understanding of topoisomerases, it becomes clear that the supercoiling of double stranded DNA plays an important role in DNA replication, RNA transcription and even in the control of ge...With the discovery and further understanding of topoisomerases, it becomes clear that the supercoiling of double stranded DNA plays an important role in DNA replication, RNA transcription and even in the control of gene expression. Although the small circular DNA can be separated by means of density gradient centrifugation or gel electrophoresis and展开更多
Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved e...Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved electron energy-loss spectroscopy(EELS) analysis. The ceramics were pyrolyzed at1000℃ followed by further annealing in N2, and SiC nano-crystallites start to emerge at 1200℃ and dominate at 1500℃. Observed by high-angle annular dark-field imaging, bright and dark clusters were revealed as universal nano-structured features in ceramic matrices before and after nucleation, and the growth of cluster size saturated before reaching 5 nm at 1400℃. EELS analysis demonstrated the gradual development of bonding structures successively into SiC, graphetic BNCxand Si3N4 phases, as well as a constant presence of unexpected oxygen in the matrices. Furthermore, EELS profiling revealed the bright SiC clusters and less bright Si3N4-like clusters at 1200–1400℃. Since the amorphous matrix has already phase separated into SiCN and carbon clusters, another phase separation of SiCN into SiC and Si3N4-like clusters might occur by annealing to accompany their nucleation and growth, albeit one crystallized and another remained in amorphous structure. Hinderance of the cluster growth and further crystallization was owing to the formation of BNCxlayers that developed between SiC and Si3N4-like clusters as well as from the excessive oxygen to form the stable SiO2.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
Both the accurate distance measurement and positioning information at the nanoscale are important for the analysis of micro/nano interactions.Plasmon ruler has been an indispensable optical tool to detect the chemical...Both the accurate distance measurement and positioning information at the nanoscale are important for the analysis of micro/nano interactions.Plasmon ruler has been an indispensable optical tool to detect the chemical and biological dynamic processes via distance-dependent plasmon coupling in the nearly aggregated state.But it cannot disclose the detailed and accurate information of positions and dynamic movements of its two plasmonic components owing to the inherent diffraction limit.Herein,a plasmonic locator is presented which consists of a heterotypic pair of red/blue plasmonic components with significant wavelength difference(∼150 nm).Attributed to the detuned energy(∼0.64 eV)of the two components,the plasmonic locator has the ability of sub-diffraction-limited resolution(center to center,30 nm)and accurate positioning under conventional dark-field microscopy,making the relative dynamic information of nearby red/blue components be recorded accurately at video rate.As an important complement to the current aggregate science and technology of plasmonics,this newly developed plasmonic locator presents a facile means to realize super-resolution imaging,accurate positioning,and continuous tracing in chemical and biological interactions at the single-molecule level.展开更多
Identification of the catalytic dynamics and plasmonic effects plays a critical role in the design of heterogeneous catalysts.However,the knowledge of plasmonic effect on catalytic dynamics remains limited at the sing...Identification of the catalytic dynamics and plasmonic effects plays a critical role in the design of heterogeneous catalysts.However,the knowledge of plasmonic effect on catalytic dynamics remains limited at the single-particle level.Using the non-fluorescent amplex red to fluorescent resorufin as a model reaction,significant enhancement in catalytic efficiency from the coupled Au nanocube dimer(AuCD)was clearly revealed with the single-molecule fluorescence microscopy.AuCD exhibits noticeably higher catalytic efficiency than the monomer,which is attributed to the spontaneous dynamic surface restructuring.Spatiotemporally resolved dynamics suggest that the active catalytic sites essentially originate from the plasmonic nanogap where an electromagnetic(EM)hot spot exists.The enhanced EM field accelerates the generation of hot carriers and promotes the spontaneous surface restructuring by enhancing the lattice vibrations,which ultimately improves the catalytic activity.These microscopic views provide new insights into the effect of EM fields on surface restructuring dynamics of nanocatalysts.展开更多
Objective： Hemodilution changes the physical properties of blood by reducing its hematocrit and blood viscosity. We tested whether prolonged hypervolemic hemodilution （HHD） impairs functional capillary density （FC...Objective： Hemodilution changes the physical properties of blood by reducing its hematocrit and blood viscosity. We tested whether prolonged hypervolemic hemodilution （HHD） impairs functional capillary density （FCD） of ileal mucosa in healthy mechanically-ventilated pigs and if there is any correlation between changes in FCD of ileal and sublingual mucosas during HHD. Methods： Sixteen domestic female pigs were anesthetized, mechanically-ventilated, and randomly assigned to the HHD （20 ml/（kg.h） Hartmann＇s solution for 3 h） or fluid restrictive （5 ml/（kg-h） Hartmann＇s solution for 3 h） group. Microcirculations of sublingual and ileal mucosas via ileostomy were visualized using sidestream dark-field （SDF） imaging at baseline conditions （t=0 h） and at selected time intervals of fluid therapy （t=-l, 2, and 3 h）. Results： A significant decrease of ileal FCD （285 （278-292） cm/cm^2） in the HHD group was observed after the third hour of HHD when compared to the baseline （360 （350-370） cm/cm2） （P〈0.01）. This trend was not observed in the restrictive group, where the ileal mucosa FCD was significantly higher after the third hour of fluid therapy as compared to the HHD group （P〈0.01）. No correlation between microhemodynamic parameters obtained from sublingual and ileal mucosas was found throughout the study. Conclusions： Prolonged HHD established by crystalloid solution significantly decreased ileal villus FCD when compared to restrictive fluid regimen. An inappropriate degree of HHD can be harmful during uncomplicated abdominal surgery.展开更多
High-entropy alloys(HEAs)contain multiple principal alloying elements,but usually with simple crystal structures.Quasicrystals are structurally complex phases,but are generally dominated by only one element.However,ne...High-entropy alloys(HEAs)contain multiple principal alloying elements,but usually with simple crystal structures.Quasicrystals are structurally complex phases,but are generally dominated by only one element.However,nearequiatomic high-entropy quasicrystals have rarely been reported because they are difficult to prepare experimentally and predict theoretically.Therefore,the preparation and crystal structures of near-equiatomic high-entropy quasicrystals have drawn much interest.We report a quinary decagonal quasicrystal(DQC)with near-equiatomic alloying elements in Al20Si20Mn20Fe20Ga20 melt-spun ribbons,which is the first to our knowledge.Meanwhile,the structural features of the DQC are characterized in detail.The configurational entropy of both the alloy and DQC satisfies the entropy-based criterion for HEAs,suggesting a high-entropy DQC.Our findings provide a new strategy to develop high-entropy quasicrystals.展开更多
基金supported by National Natural Science Foundation of China(Nos.61473293,61227804 and 61303177)
文摘Surface particles growing in large aperture optical element （LAOE） have significant impact on LAOE＇s stable operation. It is a challenge for the online system to inspect the particles with long working distance, enough precision and high efficiency because of the system constraints. In this paper, an effective and portable inspection instrument is designed based on dark-field imaging principle. A Nikon lens and an industrial high definition （HD） camera are selected to construct the vision system to inspect particles of microns size spreading over hundreds of millimeters. Using two motors and other mechanical structure, the system can realize auto-focus and image rectification functions. The line light sources are installed on both sides of the LAOE in a sealed box while the vision system is portable and working outside the box. An adaptive binarization method is proposed to process the captured dark-field image. The distribution of particles on the LAOE＇s surface is investigated. Because of the high resolution of the captured image, the SSE2 instructions optimization method is used to reduce the time cost of the algorithm. Experiments show that the instrument can inspect LAOE effectively and accurately.
基金This work was financially supported by the National Natural Science Foundation of China （NSFC, No. 21535006）.
文摘Real-time monitoring of reaction processes is helpful for understanding the reaction mechanisms. In this study we investigated the etching mechanism of gold nanopartides （AuNPs） by iodine on a single-nanopartide level because AuNPs have become important nanoprobes with applications in sensing and bioimaging fields owing to their specific localized surface plasmon resonance （LSPR） properties. By using a scattered-light dark-field microscopic imaging （iDFM） technique, the in situ KI/I2-treated etching processes of various shapes of AuNPs, including nanospheres （AuNSs）, nanorods （AuNRs）, and nanotrigonal prisms （AuNTs）, were monitored in real time. It was found that the scattered light of the different shapes of AuNPs exhibited noticeable color changes upon exposure to the etching solution. The scattering spectra during the etching process showed obvious blue-shifts with decreasing scattered intensity owing to the oxidation of Au atoms into [AuI2]-. Both finite-difference time-domain （FDTD） simulations and monitoring of morphological variations proved that the etching was a thermodynamic-dependent process through a chamfering mechanism coupled with layer-by-layer peeling, resulting in isotropic spheres with decreased particle sizes.
基金supported by the National Natural Science Foundation of China(No.52275528)the Hefei Municipal Natural Science Foundation(No.2022018)+1 种基金the Open Foundation of Key Laboratory of High-Power Laser and Physics,Chinese Academy of Sciences(No.SGKF202108)the China Scholarship Council(No.202206695004)。
文摘Fabrication of high-quality optics puts a strong demand on high-throughput detection of macroscopic bulk defects in optical components.A dark-field line confocal imaging method is proposed with two distinct advantages:(ⅰ)a point-to-line confocal scheme formed by a columnar elliptical mirror and an optical fiber bundle breaks through the constraint on light collection angle and field of view in the traditional line confocal microscopy using an objective,allowing for an extended confocal line field of more than 100 mm while maintaining a light collection angle of 27°;(ⅱ)the bulk defects are independently illuminated as a function of time to eliminate the cross talk in the direction of the confocal slit,thus preserving point confocality and showing the optical section thicknesses to be 162μm in the axial direction,and 19 and 22μm in the orthogonal transverse directions.The experimental results verify that the method has a minimum detectable bulk defect of less than 5μm and an imaging efficiency of 400 mm2/s.The method shows great potential in high-throughput and highsensitivity bulk defects detection.
基金supported by the National Natural Science Foundation of China (21035005)the Ministry of Science and Technology of the People's Republic of China (2011CB933600)the Postgraduate Science and Technology Innovation Program of Southwest China University (ky2011006)
文摘Single scattering particles,especially noble metal(plasmonic) nanoparticles,based analytical techniques are attractive recently and becoming the research focus of the light scattering analytical techniques.In this mini review,we summarize the single scattering particles based analytical techniques in the past decade including single scattering particles counting,single plasmonic nanoparticles sensing,and single plasmonic nanoparticles tracking/imaging.We emphasize the discussion on the single plasmonic nanoparticles sensing that combines with dark-field microscopy and resonant Rayleigh scattering spectroscopy.
基金funded by the National Natural Science Foundation of China (Z.P.81560131)Subject Cultivation Project of Zhongnan Hospital of Wuhan University (Bo Hu,No.ZNXKPY2021002)+1 种基金Translational Medicine and Interdisciplinary Research Joint Fund of Zhongnan Hospital of Wuhan University (Bo Hu,No.ZNJC202011)Qinghai Province Key R&D and Transformation Projects (S.M.2019-SF-132).
文摘Background The benefits of early use of norepinephrine in endotoxemic shock remain unknown.We aimed to elucidate the effects of different doses of norepinephrine in early-stage endotoxemic shock using a clinically relevant large animal model.Methods Vasodilatory shock was induced by endotoxin bolus in 30 Bama suckling pigs.Treatment included fluid resuscitation and administration of different doses of norepinephrine,to induce return to baseline mean arterial pressure(MAP).Fluid management,hemodynamic,microcirculation,inflammation,and organ function variables were monitored.All animals were supported for 6 h after endotoxemic shock.Results Infused fluid volume decreased with increasing norepinephrine dose.Return to baseline MAP was achieved more frequently with doses of 0.8µg/kg/min and 1.6µg/kg/min(P<0.01).At the end of the shock resuscitation period,cardiac index was higher in pigs treated with 0.8µg/kg/min norepinephrine(P<0.01),while systemic vascular resistance was higher in those receiving 0.4µg/kg/min(P<0.01).Extravascular lung water level and degree of organ edema were higher in animals administered no or 0.2µg/kg/min norepinephrine(P<0.01),while the percentage of perfused small vessel density(PSVD)was higher in those receiving 0.8µg/kg/min(P<0.05)and serum lactate was higher in the groups administered no and 1.6µg/kg/min norepinephrine(P<0.01).Conclusions The impact of norepinephrine on the macro-and micro-circulation in early-stage endotoxemic shock is dose-dependent,with very low and very high doses resulting in detrimental effects.Only an appropriate norepinephrine dose was associated with improved tissue perfusion and organ function.
基金the Natural Science Foundation of China(Grant Nos.U1532113,11475170,and 11905041)Fundamental Research Funds for the Central Universities(Grant No.PA2020GDKC0024)Anhui Provincial Natural Science Foundation(Grant No.2208085MA18).
文摘X-ray dark-field imaging using a grating interferometer has shown potential benefits for a variety of applications in recent years.X-ray dark-field image is commonly retrieved by using discrete Fourier transform from the acquired phasestepping data.The retrieval process assumes a constant phase step size and a constant flux for each stepped grating position.However,stepping errors and flux fluctuations inevitably occur due to external vibrations and/or thermal drift during data acquisition.Previous studies have shown that those influences introduce errors in the acquired phase-stepping data,which cause obvious moiréartifacts in the retrieved refraction image.This work investigates moiréartifacts in x-ray dark-field imaging as a result of flux fluctuations.For the retrieved mean intensity,amplitude,visibility and dark-field images,the dependence of moiréartifacts on flux fluctuation factors is theoretically derived respectively by using a first-order Taylor series expansion.Results of synchrotron radiation experiments verify the validity of the derived analytical formulas.The spatial frequency characteristics of moiréartifacts are analyzed and compared to those induced by phase-stepping errors.It illustrates that moiréartifacts can be estimated by a weighted mean of flux fluctuation factors,with the weighting factors dependent on the moiréphase and different greatly for each retrieved image.Furthermore,moiréartifacts can even be affected by object’s features not displayed in the particular contrast.These results can be used to interpret images correctly,identify sources of moiréartifacts,and develop dedicated algorithms to remove moiréartifacts in the retrieved multi-contrast images.
基金supported by grants from the National Natural Science Foundation of China(Nos.22022412,22274076,21874155)the Primary Research&Development Plan of Jiangsu Province(No.BE2022793)。
文摘Integrating discrete plasmonic nanoparticles into assemblies can induce plasmonic coupling that produces collective plasmonic properties,which are not available for single nanoparticles.Theoretical analysis revealed that plasmonic coupling derived from assemblies could produce stronger electromagnetic field enhancement effects.Thus,plasmonic assemblies enable better performance in plasmon-based applications,such as enhanced fluorescence and Raman effects.This makes them hold great potential for trace analyte detection and nanomedicine.Herein,we focus on the recent advances in various plasmonic nanoassembles such as dimers,tetramers,and core-satellite structures,and discuss their applications in biosensing and cell imaging.The fabrication strategies for self-assembled plasmonic nanostructures are described,including top-down strategies,self-assembly methods linked by DNA,ligand,polymer,amino acid,or proteins,and chemical overgrowth methods.Thereafter,their applications in biosensor and cell imaging based on dark-field imaging,surface-enhanced Raman scattering,plasmonic circular dichroism,and fluorescence imaging are discussed.Finally,the remaining challenges and prospects are elucidated.
基金the Australian Research Council (ARC) for funding this work[Grant no.DP190103592]the use of instruments and scientific and technical assistance at the Monash Centre for Electron Microscopy,a Node of Microscopy Australiafunded by ARC grants LE110100223(F20),LE0454166(Titan)and LE170100118(Spectra-φ)。
文摘Magnesium-lithium alloys with high lithium content have been attracting significant attention because of their low density,high formability and corrosion resistance.These properties are dependent on the distribution of lithium,which is difficult to map in the presence of magnesium.In this work,a ratio spectrum-imaging method with electron energy-loss spectroscopy(EELS)is demonstrated,which enables the mapping of lithium.In application to LAZ941(Mg-9Li-4Al-1Zn in wt.%),this technique revealed that a key precipitate in the microstructure,previously thought by some to be Mg_(17)Al_(12),is in fact rich in lithium.This result was corroborated with a structural investigation by high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),showing this phase to be Al_(1-x)Zn_(x)Li,with x<<1.This work indicates the potential offered by this technique for mapping lithium in materials.
基金supported by the National Natural Science Foundation of China(Nos.61627825 and 11275172)the State Key Laboratory of Modern Optical Instrumentation Innovation Program(MOI)(No.MOI2015 B06)
文摘In recent years, modern optical processing technologies, such as single point diamond turning, ion beam etching, and magneto-theological finishing, arc getting break- throughs. Machining precisions of super-smooth optics have also been significantly improved. However, with increasing demands for the optical surface quality,
文摘With the discovery and further understanding of topoisomerases, it becomes clear that the supercoiling of double stranded DNA plays an important role in DNA replication, RNA transcription and even in the control of gene expression. Although the small circular DNA can be separated by means of density gradient centrifugation or gel electrophoresis and
基金financially supported by National Natural Science Foundation of China (Grant Nos. 51172255 and 51532006)
文摘Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved electron energy-loss spectroscopy(EELS) analysis. The ceramics were pyrolyzed at1000℃ followed by further annealing in N2, and SiC nano-crystallites start to emerge at 1200℃ and dominate at 1500℃. Observed by high-angle annular dark-field imaging, bright and dark clusters were revealed as universal nano-structured features in ceramic matrices before and after nucleation, and the growth of cluster size saturated before reaching 5 nm at 1400℃. EELS analysis demonstrated the gradual development of bonding structures successively into SiC, graphetic BNCxand Si3N4 phases, as well as a constant presence of unexpected oxygen in the matrices. Furthermore, EELS profiling revealed the bright SiC clusters and less bright Si3N4-like clusters at 1200–1400℃. Since the amorphous matrix has already phase separated into SiCN and carbon clusters, another phase separation of SiCN into SiC and Si3N4-like clusters might occur by annealing to accompany their nucleation and growth, albeit one crystallized and another remained in amorphous structure. Hinderance of the cluster growth and further crystallization was owing to the formation of BNCxlayers that developed between SiC and Si3N4-like clusters as well as from the excessive oxygen to form the stable SiO2.
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National Natural Science Foundation of China,Grant/Award Numbers:21605125,21874109,22134005Natural Science Foundation of Chongqing,Grant/Award Number:cstc2020jcyj-msxmX0992。
文摘Both the accurate distance measurement and positioning information at the nanoscale are important for the analysis of micro/nano interactions.Plasmon ruler has been an indispensable optical tool to detect the chemical and biological dynamic processes via distance-dependent plasmon coupling in the nearly aggregated state.But it cannot disclose the detailed and accurate information of positions and dynamic movements of its two plasmonic components owing to the inherent diffraction limit.Herein,a plasmonic locator is presented which consists of a heterotypic pair of red/blue plasmonic components with significant wavelength difference(∼150 nm).Attributed to the detuned energy(∼0.64 eV)of the two components,the plasmonic locator has the ability of sub-diffraction-limited resolution(center to center,30 nm)and accurate positioning under conventional dark-field microscopy,making the relative dynamic information of nearby red/blue components be recorded accurately at video rate.As an important complement to the current aggregate science and technology of plasmonics,this newly developed plasmonic locator presents a facile means to realize super-resolution imaging,accurate positioning,and continuous tracing in chemical and biological interactions at the single-molecule level.
基金This research was made possible by a generous grant from National Natural Science Foundation of China(NSFC,project no.21974073).
文摘Identification of the catalytic dynamics and plasmonic effects plays a critical role in the design of heterogeneous catalysts.However,the knowledge of plasmonic effect on catalytic dynamics remains limited at the single-particle level.Using the non-fluorescent amplex red to fluorescent resorufin as a model reaction,significant enhancement in catalytic efficiency from the coupled Au nanocube dimer(AuCD)was clearly revealed with the single-molecule fluorescence microscopy.AuCD exhibits noticeably higher catalytic efficiency than the monomer,which is attributed to the spontaneous dynamic surface restructuring.Spatiotemporally resolved dynamics suggest that the active catalytic sites essentially originate from the plasmonic nanogap where an electromagnetic(EM)hot spot exists.The enhanced EM field accelerates the generation of hot carriers and promotes the spontaneous surface restructuring by enhancing the lattice vibrations,which ultimately improves the catalytic activity.These microscopic views provide new insights into the effect of EM fields on surface restructuring dynamics of nanocatalysts.
基金Project (No. MZO 00179906) supported by the Ministry of Health,Czech Republic
文摘Objective： Hemodilution changes the physical properties of blood by reducing its hematocrit and blood viscosity. We tested whether prolonged hypervolemic hemodilution （HHD） impairs functional capillary density （FCD） of ileal mucosa in healthy mechanically-ventilated pigs and if there is any correlation between changes in FCD of ileal and sublingual mucosas during HHD. Methods： Sixteen domestic female pigs were anesthetized, mechanically-ventilated, and randomly assigned to the HHD （20 ml/（kg.h） Hartmann＇s solution for 3 h） or fluid restrictive （5 ml/（kg-h） Hartmann＇s solution for 3 h） group. Microcirculations of sublingual and ileal mucosas via ileostomy were visualized using sidestream dark-field （SDF） imaging at baseline conditions （t=0 h） and at selected time intervals of fluid therapy （t=-l, 2, and 3 h）. Results： A significant decrease of ileal FCD （285 （278-292） cm/cm^2） in the HHD group was observed after the third hour of HHD when compared to the baseline （360 （350-370） cm/cm2） （P〈0.01）. This trend was not observed in the restrictive group, where the ileal mucosa FCD was significantly higher after the third hour of fluid therapy as compared to the HHD group （P〈0.01）. No correlation between microhemodynamic parameters obtained from sublingual and ileal mucosas was found throughout the study. Conclusions： Prolonged HHD established by crystalloid solution significantly decreased ileal villus FCD when compared to restrictive fluid regimen. An inappropriate degree of HHD can be harmful during uncomplicated abdominal surgery.
基金the National Natural Science Foundation of China(51871015 and 51471024)the Selfdetermined Project of the State Key Laboratory for Advanced Metals and Materials(2016Z-13)。
文摘High-entropy alloys(HEAs)contain multiple principal alloying elements,but usually with simple crystal structures.Quasicrystals are structurally complex phases,but are generally dominated by only one element.However,nearequiatomic high-entropy quasicrystals have rarely been reported because they are difficult to prepare experimentally and predict theoretically.Therefore,the preparation and crystal structures of near-equiatomic high-entropy quasicrystals have drawn much interest.We report a quinary decagonal quasicrystal(DQC)with near-equiatomic alloying elements in Al20Si20Mn20Fe20Ga20 melt-spun ribbons,which is the first to our knowledge.Meanwhile,the structural features of the DQC are characterized in detail.The configurational entropy of both the alloy and DQC satisfies the entropy-based criterion for HEAs,suggesting a high-entropy DQC.Our findings provide a new strategy to develop high-entropy quasicrystals.
