The turbulence structure in the stirred tank with a deep hollow blade(semi-ellispe) disc turbine(HEDT) was investigated by using time-resolved particle image velocimetry(TRPIV) and traditional PIV.In the stirred tank,...The turbulence structure in the stirred tank with a deep hollow blade(semi-ellispe) disc turbine(HEDT) was investigated by using time-resolved particle image velocimetry(TRPIV) and traditional PIV.In the stirred tank,the turbulence generated by blade passage includes the periodic components and the random turbulent ones.Traditional PIV with angle-resolved measurement and TRPIV with wavelet analysis were both used to obtain the random turbulent kinetic energy as a comparison.The wavelet analysis method was successfully used in this work to separate the random turbulent kinetic energy.The distributions of the periodic kinetic energy and the random turbulent kinetic energy were obtained.In the impeller region,the averaged random turbulent kinetic energy was about 2.6 times of the averaged periodic one.The kinetic energies at different wavelet scales from a6 to d1 were also calculated and compared.TRPIV was used to record the sequence of instantaneous velocity in the impeller stream.The evolution of the impeller stream was observed clearly and the sequence of the vorticity field was also obtained for the identification of vortices.The slope of the energy spectrum was approximately-5/3 in high frequency representing the existence of inertial subrange and some isotropic properties in stirred tank.From the power spectral density(PSD) ,one peak existed evidently,which was located at f0(blade passage frequency) generated by the blade passage.展开更多
We performed a quantitative analysis of time-resolved laser-induced breakdown air plasma spectra to obtain the evolution of temperatures and species relative fractions.The air plasma was generated by focusing a 100 mJ...We performed a quantitative analysis of time-resolved laser-induced breakdown air plasma spectra to obtain the evolution of temperatures and species relative fractions.The air plasma was generated by focusing a 100 mJ Nd:YAG laser pulse,and the time-resolved spectra were recorded by an intensified charge-coupled device camera with incremental delay.The attention was mainly focused on the emission spectra of the first negative system of nitrogen(N_(2)^(+),B^(2)Σ-(u)^(-)-X^(2)Σ^(+)g)and the violet system of carbon nitride(CN,B^(2)Σ^(+)-X^(2)Σ^(+))located at 383-396 nm.A custom-built model was developed to perform the simulation and fitting of the N_(2)^(+)and the CN spectra from the air plasma.The model was verified by comparing to a published model with a 0.9860 Spearman correlation coefficient.With this model,the time-resolved non-equilibrium temperatures and relative fractions of N_(2)^(+)and CN were obtained with a fitting correlation coefficient higher than 0.9108.展开更多
Photoswitchable fluorescent polymeric nanoparticles were widely concerned because of their excellent features including the flexible design,easy preparation and functionalization,and thus exhibited great application p...Photoswitchable fluorescent polymeric nanoparticles were widely concerned because of their excellent features including the flexible design,easy preparation and functionalization,and thus exhibited great application potential in information encryption,anti-counterfeiting,but remained challenging in improving the security.Herein,we described a self-erased time-resolved information encryption via using photoswitchable dual-color fluorescent polymeric nanoparticles(PDFPNs)containing two fluorescence dyes(blue and red)and photochromic spiroxazine derivatives.In view of the different thermo-induced isomerization rates of photochromic spiroxazine derivatives in different flexible substrates,the decoloration rate of PDFPNs can be programmatically tuned by regulating ratio between rigid polymer and flexible polymer.Therefore,after ultraviolet light(UV)irradiation,correct information could only be recognized in preestablished time during the self-erased process.Our results indicated that PDFPNs exhibited fast photo-responsibility(2 min),high fluorescence contrast,well-pleasing photo-reversibility(>20 times),and programmable thermo-responsiveness(24 s-6 h).We thus demonstrated their application in the selferased time-resolved information encryption and anti-counterfeiting with high security.展开更多
Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell paramet...Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell parameter thereby providing a unique approach for high-throughput cell counting and screening.Differences in fluorescence lifetime were detected and this was associated with sensitivity to the commonly prescribed therapeutic tamoxifen.Differences in fluorescence lifetime are attributed to the binding states of the autofluorescent metabolite NAD(P)H.The function of NAD(P)H is well described and in general involves cycling from a reduced to oxidized state to facilitate electron transport for the conversion of pyruvate to lactate.NAD(P)H fluorescence lifetimes depend on the bound or unbound state of the metabolite,which also relates to metabolic transitions between oxidative phosphorylation and glycolysis.To determine if fundamental metabolic profiles differ for cells that are sensitive to tamoxifen compared to those that are resistant,large populations of MCF-7 breast cancer cells were screened and fluorescence lifetimes were quantified.Additionally,metabolic differences associated with tamoxifen sensitivity were measured with a Seahorse HS mini metabolic analyzer(Agilent Technologies Inc.Santa Clara,CA)and confocal imaging.Results show that tamoxifen-resistant breast cancer cells have increased utilization of glycolysis for energy production compared to tamoxifen-sensitive breast cancer cells.This work is impacting because it establishes an early step toward developing a reliable screening technology in which large cell censuses can be differentiated for drug sensitivity in a label-free fashion.展开更多
Compared with the conventional first near-infrared(NIR-I,700900 nm)window,the short-wave infrared region(SWIR,900—1700nm)possesses the merits of the increasing tissue penetration depths and the suppression of scatter...Compared with the conventional first near-infrared(NIR-I,700900 nm)window,the short-wave infrared region(SWIR,900—1700nm)possesses the merits of the increasing tissue penetration depths and the suppression of scattering background,leading to great potential for in vivo imaging.Based on the limitations of the common spectral domain,and the superiority of the time-dimension,time-resolved imaging eliminates the auto-fuorescence in the biological tissue,thus supporting higher signal-to-noise ratio and sensitivities.The imaging technique is not affected by the difference in tissue composition or thickness and has the practical value of quan-titative in vivo detection.Almost all the relevant time-resolved imaging was carried out around lanthanide-doped upconversion nanomaterials,owing to the advantages of ultralong luminescence lifetime,excellent photostability,controllable morphology,easy surface modification and various strategies of regulating lifetime.Therefore,this review presents the research progress of SWIR time-resolved imaging technology based on nanomaterials doped with lanthanide ions as luminescence centers in recent years.展开更多
We measure the time-resolved terahertz spectroscopy of GeSn thin film and studied the ultrafast dynamics of its photo-generated carriers.The experimental results show that there are photo-generated carriers in GeSn un...We measure the time-resolved terahertz spectroscopy of GeSn thin film and studied the ultrafast dynamics of its photo-generated carriers.The experimental results show that there are photo-generated carriers in GeSn under femtosecond laser excitation at 2500 nm,and its pump-induced photoconductivity can be explained by the Drude–Smith model.The carrier recombination process is mainly dominated by defect-assisted Auger processes and defect capture.The firstand second-order recombination rates are obtained by the rate equation fitting,which are(2.6±1.1)×10^(-2)ps^(-1)and(6.6±1.8)×10^(-19)cm^(3)·ps^(-1),respectively.Meanwhile,we also obtain the diffusion length of photo-generated carriers in GeSn,which is about 0.4μm,and it changes with the pump delay time.These results are important for the GeSn-based infrared optoelectronic devices,and demonstrate that Ge Sn materials can be applied to high-speed optoelectronic detectors and other applications.展开更多
In this paper,self-designed multi-hollow needle electrodes are used as a high-voltage electrode in a packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and ac...In this paper,self-designed multi-hollow needle electrodes are used as a high-voltage electrode in a packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large-volume stable discharge.The dynamic characteristics of the plasma,the generated active species,and the energy transfer mechanisms in both positive discharge(PD)and negative discharge(ND)are investigated by using fast-exposure intensified charge coupled device(ICCD)images and time-resolved optical emission spectra.The experimental results show that the discharge intensity,number of discharge channels,and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multihollow needle electrode.During a single voltage pulse period,PD mainly develops in a streamer mode,which results in a stronger discharge current,luminous intensity,and E/N compared with the diffuse mode observed in ND.In PD,as the gap between dielectric beads changes from 0 to250μm,the discharge between the dielectric bead gap changes from a partial discharge to a standing filamentary micro-discharge,which allows the plasma to leave the local area and is conducive to the propagation of surface streamers.In ND,the discharge only appears as a diffusionlike mode between the gap of dielectric beads,regardless of whether there is a discharge gap.Moreover,the generation of excited states N_(2)^(+)(B^(2)∑_(u)^(+))and N2(C^(3)Π_(u))is mainly observed in PD,which is attributed to the higher E/N in PD than that in ND.However,the generation of the OH(A^(2)∑^(+))radical in ND is higher than in PD.It is not directly dominated by E/N,but mainly by the resonant energy transfer process between metastable N_(2)(A^(3)∑_(u)^(+))and OH(X^(2)Π).Furthermore,both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration,and no vibration-to-rotation energy relaxation process is observed.展开更多
[Objectives]This study was conducted to explore rapid and large-scale screening and detection of peste des petits ruminants(PPR),so as to provide important technical means for prevention,control and purification of PP...[Objectives]This study was conducted to explore rapid and large-scale screening and detection of peste des petits ruminants(PPR),so as to provide important technical means for prevention,control and purification of PPR.[Methods]Soluble N protein and NH fusion protein were successfully obtained in an Escherichia coli expression system by optimizing E.coli codon and expression conditions.Furthermore,based on purified soluble N protein and NH fusion protein,a double-antigen sandwich time-resolved fluorescence immunoassay method for detection of peste des petits ruminants virus(PPRV)was established.[Results]The method has high sensitivity and specificity and can specifically detect the antibody against PPRV in sheep serum,and it has no cross reaction with other related diseases.The method was used to detect 292 clinical samples,and compared with French IDVET competition ELISA kit.The coincidence rates of positive samples and negative samples from the two kinds of test kits were 92.47%and 97.26%,respectively,and the overall coincidence rate was 94.86%.The intra-group and inter-group coefficients of variation in the repeatability test were less than 10%.[Conclusions]Compared with the traditional ELISA method,the double-antigen sandwich time-resolved fluorescence immunoassay for detection of PPRV has equivalent sensitivity and specificity,and simple and rapid operation,and thus high application and popularization value.展开更多
基金Supported by the National Natural Science Foundation of China（20776008 20821004 20990224） the National Basic Research Program of China（2007CB714300）
文摘The turbulence structure in the stirred tank with a deep hollow blade(semi-ellispe) disc turbine(HEDT) was investigated by using time-resolved particle image velocimetry(TRPIV) and traditional PIV.In the stirred tank,the turbulence generated by blade passage includes the periodic components and the random turbulent ones.Traditional PIV with angle-resolved measurement and TRPIV with wavelet analysis were both used to obtain the random turbulent kinetic energy as a comparison.The wavelet analysis method was successfully used in this work to separate the random turbulent kinetic energy.The distributions of the periodic kinetic energy and the random turbulent kinetic energy were obtained.In the impeller region,the averaged random turbulent kinetic energy was about 2.6 times of the averaged periodic one.The kinetic energies at different wavelet scales from a6 to d1 were also calculated and compared.TRPIV was used to record the sequence of instantaneous velocity in the impeller stream.The evolution of the impeller stream was observed clearly and the sequence of the vorticity field was also obtained for the identification of vortices.The slope of the energy spectrum was approximately-5/3 in high frequency representing the existence of inertial subrange and some isotropic properties in stirred tank.From the power spectral density(PSD) ,one peak existed evidently,which was located at f0(blade passage frequency) generated by the blade passage.
基金Project supported by the National Natural Science Foundation of China(Grant No.62305087)。
文摘We performed a quantitative analysis of time-resolved laser-induced breakdown air plasma spectra to obtain the evolution of temperatures and species relative fractions.The air plasma was generated by focusing a 100 mJ Nd:YAG laser pulse,and the time-resolved spectra were recorded by an intensified charge-coupled device camera with incremental delay.The attention was mainly focused on the emission spectra of the first negative system of nitrogen(N_(2)^(+),B^(2)Σ-(u)^(-)-X^(2)Σ^(+)g)and the violet system of carbon nitride(CN,B^(2)Σ^(+)-X^(2)Σ^(+))located at 383-396 nm.A custom-built model was developed to perform the simulation and fitting of the N_(2)^(+)and the CN spectra from the air plasma.The model was verified by comparing to a published model with a 0.9860 Spearman correlation coefficient.With this model,the time-resolved non-equilibrium temperatures and relative fractions of N_(2)^(+)and CN were obtained with a fitting correlation coefficient higher than 0.9108.
基金financially supported by the National Key R&D Program of China(Nos.2023YFB3812400,2023YFB3812403)National Natural Foundation of China(Nos.52273206,52350233)+1 种基金Hunan Provincial Natural Science Foundation(No.2021JJ10029)Huxiang High-level Talent Gathering Project(No.2022RC4039).
文摘Photoswitchable fluorescent polymeric nanoparticles were widely concerned because of their excellent features including the flexible design,easy preparation and functionalization,and thus exhibited great application potential in information encryption,anti-counterfeiting,but remained challenging in improving the security.Herein,we described a self-erased time-resolved information encryption via using photoswitchable dual-color fluorescent polymeric nanoparticles(PDFPNs)containing two fluorescence dyes(blue and red)and photochromic spiroxazine derivatives.In view of the different thermo-induced isomerization rates of photochromic spiroxazine derivatives in different flexible substrates,the decoloration rate of PDFPNs can be programmatically tuned by regulating ratio between rigid polymer and flexible polymer.Therefore,after ultraviolet light(UV)irradiation,correct information could only be recognized in preestablished time during the self-erased process.Our results indicated that PDFPNs exhibited fast photo-responsibility(2 min),high fluorescence contrast,well-pleasing photo-reversibility(>20 times),and programmable thermo-responsiveness(24 s-6 h).We thus demonstrated their application in the selferased time-resolved information encryption and anti-counterfeiting with high security.
基金the National Institute of Health for supporting this research under grants NIH R35GM152076,NIH 1SC1GM127175-01,NIH T32GM148394.
文摘Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell parameter thereby providing a unique approach for high-throughput cell counting and screening.Differences in fluorescence lifetime were detected and this was associated with sensitivity to the commonly prescribed therapeutic tamoxifen.Differences in fluorescence lifetime are attributed to the binding states of the autofluorescent metabolite NAD(P)H.The function of NAD(P)H is well described and in general involves cycling from a reduced to oxidized state to facilitate electron transport for the conversion of pyruvate to lactate.NAD(P)H fluorescence lifetimes depend on the bound or unbound state of the metabolite,which also relates to metabolic transitions between oxidative phosphorylation and glycolysis.To determine if fundamental metabolic profiles differ for cells that are sensitive to tamoxifen compared to those that are resistant,large populations of MCF-7 breast cancer cells were screened and fluorescence lifetimes were quantified.Additionally,metabolic differences associated with tamoxifen sensitivity were measured with a Seahorse HS mini metabolic analyzer(Agilent Technologies Inc.Santa Clara,CA)and confocal imaging.Results show that tamoxifen-resistant breast cancer cells have increased utilization of glycolysis for energy production compared to tamoxifen-sensitive breast cancer cells.This work is impacting because it establishes an early step toward developing a reliable screening technology in which large cell censuses can be differentiated for drug sensitivity in a label-free fashion.
基金the National Natural Science Foundation of China(No.81971704)the National Key ResearchandDevelopment Program of China(No.2017YFA0205304)the Translational Medicine Research Fund of National Facility for Translational Medicine(Shanghai)(No.TMSK-2021-117)。
文摘Compared with the conventional first near-infrared(NIR-I,700900 nm)window,the short-wave infrared region(SWIR,900—1700nm)possesses the merits of the increasing tissue penetration depths and the suppression of scattering background,leading to great potential for in vivo imaging.Based on the limitations of the common spectral domain,and the superiority of the time-dimension,time-resolved imaging eliminates the auto-fuorescence in the biological tissue,thus supporting higher signal-to-noise ratio and sensitivities.The imaging technique is not affected by the difference in tissue composition or thickness and has the practical value of quan-titative in vivo detection.Almost all the relevant time-resolved imaging was carried out around lanthanide-doped upconversion nanomaterials,owing to the advantages of ultralong luminescence lifetime,excellent photostability,controllable morphology,easy surface modification and various strategies of regulating lifetime.Therefore,this review presents the research progress of SWIR time-resolved imaging technology based on nanomaterials doped with lanthanide ions as luminescence centers in recent years.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12004067,11974070,62027807,and 52272137)the National Key R&D Program of China(Grant No.2022YFA1403000)。
文摘We measure the time-resolved terahertz spectroscopy of GeSn thin film and studied the ultrafast dynamics of its photo-generated carriers.The experimental results show that there are photo-generated carriers in GeSn under femtosecond laser excitation at 2500 nm,and its pump-induced photoconductivity can be explained by the Drude–Smith model.The carrier recombination process is mainly dominated by defect-assisted Auger processes and defect capture.The firstand second-order recombination rates are obtained by the rate equation fitting,which are(2.6±1.1)×10^(-2)ps^(-1)and(6.6±1.8)×10^(-19)cm^(3)·ps^(-1),respectively.Meanwhile,we also obtain the diffusion length of photo-generated carriers in GeSn,which is about 0.4μm,and it changes with the pump delay time.These results are important for the GeSn-based infrared optoelectronic devices,and demonstrate that Ge Sn materials can be applied to high-speed optoelectronic detectors and other applications.
基金supported by National Natural Science Foundations of China(Nos.51977023 and 52077026)the Fundamental Research Funds for the Central Universities(No.DUT23YG227)。
文摘In this paper,self-designed multi-hollow needle electrodes are used as a high-voltage electrode in a packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large-volume stable discharge.The dynamic characteristics of the plasma,the generated active species,and the energy transfer mechanisms in both positive discharge(PD)and negative discharge(ND)are investigated by using fast-exposure intensified charge coupled device(ICCD)images and time-resolved optical emission spectra.The experimental results show that the discharge intensity,number of discharge channels,and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multihollow needle electrode.During a single voltage pulse period,PD mainly develops in a streamer mode,which results in a stronger discharge current,luminous intensity,and E/N compared with the diffuse mode observed in ND.In PD,as the gap between dielectric beads changes from 0 to250μm,the discharge between the dielectric bead gap changes from a partial discharge to a standing filamentary micro-discharge,which allows the plasma to leave the local area and is conducive to the propagation of surface streamers.In ND,the discharge only appears as a diffusionlike mode between the gap of dielectric beads,regardless of whether there is a discharge gap.Moreover,the generation of excited states N_(2)^(+)(B^(2)∑_(u)^(+))and N2(C^(3)Π_(u))is mainly observed in PD,which is attributed to the higher E/N in PD than that in ND.However,the generation of the OH(A^(2)∑^(+))radical in ND is higher than in PD.It is not directly dominated by E/N,but mainly by the resonant energy transfer process between metastable N_(2)(A^(3)∑_(u)^(+))and OH(X^(2)Π).Furthermore,both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration,and no vibration-to-rotation energy relaxation process is observed.
基金Supported by National Key R&D Program for the Prevention and Control of Major Exotic Animal Diseases(2022YFD1800500)National Mutton Sheep Industrial Technology System(CARS39)+2 种基金Key Research and Development Program of Shandong Province(Major Science and Technology Innovation Project)(2021CXGC011306)Scientific Research Project of General Administration of Customs(2024HK033)Scientific Research Project of Jinan Customs(2023JK005).
文摘[Objectives]This study was conducted to explore rapid and large-scale screening and detection of peste des petits ruminants(PPR),so as to provide important technical means for prevention,control and purification of PPR.[Methods]Soluble N protein and NH fusion protein were successfully obtained in an Escherichia coli expression system by optimizing E.coli codon and expression conditions.Furthermore,based on purified soluble N protein and NH fusion protein,a double-antigen sandwich time-resolved fluorescence immunoassay method for detection of peste des petits ruminants virus(PPRV)was established.[Results]The method has high sensitivity and specificity and can specifically detect the antibody against PPRV in sheep serum,and it has no cross reaction with other related diseases.The method was used to detect 292 clinical samples,and compared with French IDVET competition ELISA kit.The coincidence rates of positive samples and negative samples from the two kinds of test kits were 92.47%and 97.26%,respectively,and the overall coincidence rate was 94.86%.The intra-group and inter-group coefficients of variation in the repeatability test were less than 10%.[Conclusions]Compared with the traditional ELISA method,the double-antigen sandwich time-resolved fluorescence immunoassay for detection of PPRV has equivalent sensitivity and specificity,and simple and rapid operation,and thus high application and popularization value.
