Late-stage modification of complex molecules via site-selective hydrodefluorination is a challenging endeavor.The selective activation of carbon-fluorine(C-F) bonds in the presence of multiple C-F bonds is of importan...Late-stage modification of complex molecules via site-selective hydrodefluorination is a challenging endeavor.The selective activation of carbon-fluorine(C-F) bonds in the presence of multiple C-F bonds is of importance in organic synthesis and drug discovery.Herein,we describe the activation of C-F bonds via multiphoton photoredox catalysis to selectively produces a series of hydrodefluorinated compounds by simply tuning the reaction conditions.Moreover,this protocol was successfully applied to the late-stage functionalization of different drug-derivatives and the corresponding mono-,di-,and tri-defluorinated products were obtained in good to excellent yields.A detailed mechanistic investigation provides insight into the unprecedented hydrodefluorination pathway.展开更多
The designing and manufacturing of micro/nanoscale tools for delivery,diagnostic,and therapeutic are essential for their multiscale integration in the precision medicine field.Conventional three-dimensional(3D)printin...The designing and manufacturing of micro/nanoscale tools for delivery,diagnostic,and therapeutic are essential for their multiscale integration in the precision medicine field.Conventional three-dimensional(3D)printing approaches are not suitable for such kind of tools due to the accuracy limitation.Multiphoton polymerization(MPP)-based micro/nanomanufacturing is a noncontact,high-precision molding technology that has been widely used in the micro/nano field is a promising tool for micro/nanoscale related precision medicine.In this article the fundamentals of MPP-based technology and the required materials in precision medicine are overviewed.The biomedical applications in various scenarios are then summarized and categorized as delivery systems,microtissue modeling,surgery,and diagnosis.Finally,the existing challenges and future perspectives on MPP-based micro/nanomanufacturing for precision medicine are discussed,focusing on material design,process optimization,and practical applications to overcome its current limitations.展开更多
Traumatic penumbra(TP)is a region with recoverable potential around the primary lesion of brain injury.Rapid and accurate imaging for identifying TP is essential for treating traumatic brain injury(TBI).In this study,...Traumatic penumbra(TP)is a region with recoverable potential around the primary lesion of brain injury.Rapid and accurate imaging for identifying TP is essential for treating traumatic brain injury(TBI).In this study,we first established traumatic brain injuries(TBIs)in rats using a modified Feeney method,followed by label-free imaging of brain tissue sections with multiphoton fluorescence microscopy.The results showed that the technique effectively imaged normal and traumatic brain tissues,and revealed pathological features such as extracellular matrix changes,vascular cell proliferation,and intracellular edema in the traumatic penumbra.Compared with normal brain tissue,the extracellular matrix in the TP was sparse,cells were disorganized,and hyperplastic vascular cells emitted higher two-photon excited fluorescence(TPEF)signals.Our research demonstrates the potential of multiphoton fluorescence technology in the rapid diagnosis and therapeutic evaluation of TBI.展开更多
We developed an imaging technique combining two-photon computed super-resolution microscopy and suction-based stabilization to achieve the resolution of the single-cell level and organelles in vivo.To accomplish this,...We developed an imaging technique combining two-photon computed super-resolution microscopy and suction-based stabilization to achieve the resolution of the single-cell level and organelles in vivo.To accomplish this,a conventional two-photon microscope was equipped with a 3D-printed holders,which stabilize the tissue surface within the focal plane of immersion objectives.Further computational image stabilization and noise reduction were applied,followed by superresolution radial fluctuations(SRRF)analysis,doubling image resolution,and enhancing signal-to-noise ratios for in vivo subcellular process investigation.Stabilization of<1μm was obtained by suction,and<25 nm were achieved by subsequent algorithmic image stabilization.A Mito-Dendra2 mouse model,expressing green fluorescent protein(GFP)in mitochondria,demonstrated the potential of long-term intravital subcellular imaging.In vivo mitochondrial fission and fusion,mitochondrial status migration,and the effects of alcohol consumption(modeled as an alcoholic liver disease)and berberine treatment on hepatocyte mitochondrial dynamics are directly observed intravitally.Suction-based stabilization in two-photon intravital imaging,coupled with computational super-resolution holds promise for advancing in vivo subcellular imaging studies.展开更多
AIM: To evaluate the feasibility of using multiphoton microscopy(MPM) to assess a tumor regression grading(TRG) system.METHODS: Fresh specimens from seven patients with colorectal carcinoma undergoing neoadjuvant radi...AIM: To evaluate the feasibility of using multiphoton microscopy(MPM) to assess a tumor regression grading(TRG) system.METHODS: Fresh specimens from seven patients with colorectal carcinoma undergoing neoadjuvant radiochemotherapy at the Fujian Medical University Union Hospital were obtained immediately after proctectomy.Specimens were serially sectioned(10 μm thickness) and used for MPM or stained with hematoxylin and eosin for comparison.Sections were imaged by MPM using 810 nm excitation, and images were collected in two wavelength channels corresponding to second-harmonic generation(SHG) and two-photon excited fluorescence(TPEF) signals.The ratio of these signal intensities was used to distinguish fibrosis from normal mucosal and serosal tissues.RESULTS: TRG of specimens assessed by MPMwere in complete agreement with histologic grading performed by a consulting pathologist.SHG and TPEF images clearly revealed collagen fibers and fragmented elastic fibers in the muscularis propria specimens following neoadjuvant radiochemotherapy.Additionally, blood vessel hyperplasia was observed as thickening and fibrosis of the intima and media, which was accompanied by minimal inflammatory cell infiltration.Furthermore, the SHG/TPEF ratio in stromal fibrosis(4.15 ± 0.58) was significantly higher than those in the normal submucosal(2.31 ± 0.52) and serosal(1.47 ± 0.10) tissues(P < 0.001 for both).Analysis of emission spectra from cancerous tumor cells revealed two peaks corresponding to nicotinamide adenine dinucleotide hydrogen and flavin adenine dinucleotide signals; the ratio of these values was 1.19 ± 0.02, which is close to a normal metabolic state.CONCLUSION: MPM can be used to perform realtime diagnosis of tumor response after neoadjuvant treatment, and can be applied to evaluate TRG.展开更多
Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical mu...Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical multiphoton resonance spectra that can be compared with the experimental data. We also obtain the time evolution of the final state in different microwave fields.展开更多
Multiphoton microscopy(MPM),with the advantages of improved penetration depth,decreased photo-damage,and optical sectioning capability,has become an indispensable tool for biomedical imaging.The combination of multiph...Multiphoton microscopy(MPM),with the advantages of improved penetration depth,decreased photo-damage,and optical sectioning capability,has become an indispensable tool for biomedical imaging.The combination of multiphoton fluorescence(MF)and second-harmonic generation(SHG)microscopy is particularly effective in imaging tissue structures of the ocular surface.This work is intended to be a review of advances that MPM has made in ophthalmic imaging.The MPM not only can be used for the label-free imaging of ocular structures,it can also be applied for investigating the morphological alterations in corneal pathologies,such as keratoconus,infected keratitis,and corneal scar.Furthermore,the corneal wound healing process after refractive surgical procedures such as conductive keratoplasty(CK)can also be studied with MPM.Finally,qualitative and quantitative SHG microscopy is effective for characterizing corneal thermal denaturation.With additional development,multiphoton imaging has the potential to be developed into an effective imaging technique for in vivo studies and clinical diagnosis in ophthalmology.展开更多
The elaborate energy and momentum spectra of ionized electrons from atoms in laser fields suggest that the ionization dynamics described by tunneling theory should be modified. Although great efforts have been carried...The elaborate energy and momentum spectra of ionized electrons from atoms in laser fields suggest that the ionization dynamics described by tunneling theory should be modified. Although great efforts have been carried out within semiclassical models, there are few discussions describing the multiphoton absorption process within a quantum framework. Comparing the results obtained with the time-dependent Schr?dinger equation(TDSE)and the Keldysh–Faisal–Reiss(KFR) theory, we study the nonperturbative effects of ionization dynamics beyond the KFR theory. The difference in momentum spectra between multiphoton and tunneling regimes is understood in a unified picture with virtual multiphoton absorption processes. For the multiphoton regime, the momentum spectra can be obtained by coherent interference of each periodic contribution. However, the interference of multiphoton absorption peaks will result in a complex structure of virtual multiphoton bands in the tunneling regime. It is shown that the virtual spectra will be almost continuous in the tunneling regime instead of the discrete levels found in the multiphoton regime. Finally, with a model combining the TDSE and the KFR theory,we try to understand the different effects of virtual multiphoton processes on ionization dynamics.展开更多
We study the ionization probabilities of atoms by a short laser pulse with three different theoretical methods, i.e., the numerical solution of the time-dependent SchrSdinger equation （TDSE）, the Perelomov-Popov Ter...We study the ionization probabilities of atoms by a short laser pulse with three different theoretical methods, i.e., the numerical solution of the time-dependent SchrSdinger equation （TDSE）, the Perelomov-Popov Terent＇ev （PPT） theory, and the Ammosov-Delone-Krainov （ADK） theory. Our results show that laser intensity dependent ionization probabilities of several atoms （i.e., H, He, and Ne） obtained from the PPT theory accord quite well with the TDSE results both in the multiphoton and tunneling ionization regimes, while the ADK results fit well to the TDSE data only in the tunneling ionization regime. Our calculations also show that laser intensity dependent ionization probabilities of a H atom at three different laser wavelengths of 600 nm, 800 nm, and 1200 nm obtained from the PPT theory are also in good agreement with those from the TDSE, while the ADK theory fails to give the wavelength dependence of ionization probability. Only when the laser wavelength is long enough, will the results of ADK be close to those of TDSE.展开更多
We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Sch...We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Schr ¨odinger equation. The photoelectron momentum distributions display many ring-like patterns for the three-photon ionization, which vary dramatically with the change of the laser wavelength. We show that the wavelength-dependent photoelectron energy spectrum can be used to effectively identify the resonant and nonresonant ionization pathways. We also find an abnormal ellipticity dependence of the electron yield for the(2+1) resonance-enhanced ionization via the 4d intermediate state, which is relevant to the two-photon excitation probability from the ground state to the 4d state.展开更多
Multiphoton microscopy, relying on the simultaneous absorption of two or more photons by a fluorophore, has come to occupy a prominent place in modern biomedical research with its ability to allow real-time observatio...Multiphoton microscopy, relying on the simultaneous absorption of two or more photons by a fluorophore, has come to occupy a prominent place in modern biomedical research with its ability to allow real-time observation of a single cell and molecules in intact tissues. Multiphoton microscopy exhibits nonlinear optical contrast properties, which can make it possible to provide an exceptionally large depth penetration with less phototoxicity. This system becomes more and more an inspiring tool for a non-invasive imaging system to realize "optical biopsy" and to examine the functions of living cells. In this review, we briefly present the physical principles and properties of multiphoton microscopy as well as the current applications in biological fields. In addition, we address what we see as the future potential of multiphoton microscopy for gastroenterologic research.展开更多
The infrared multiphoton dissociation(IRMPD)spectrum of the protonated heterodimer of Pro Phe H+,in the range of 2700-3700 cm^-1,has been obtained with a Fourier-transform ion cyclotron mass spectrometer combined with...The infrared multiphoton dissociation(IRMPD)spectrum of the protonated heterodimer of Pro Phe H+,in the range of 2700-3700 cm^-1,has been obtained with a Fourier-transform ion cyclotron mass spectrometer combined with an IR OPO laser.The experimental spectrum shows one peak at 3565 cm^-1 corresponding to the free carboxyl O-H stretching vibration,and two broad peaks centered at 2935 and 3195 cm^-1.Theoretical calculations were performed on the level of M062 X/6-311++G(d,p).Results show that the most stable isomer is characterized by a charge-solvated structure in which the proton is bound to the unit of proline.Its predicted spectrum is in good agreement with the experimental one,although the coexistence of salt-bridged structures cannot be entirely excluded.展开更多
To date,numerous studies have been performed to elucidate the complex cellular dynamics in skin diseases,but few have attempted to characterize these cellular events under conditions similar to the native environment....To date,numerous studies have been performed to elucidate the complex cellular dynamics in skin diseases,but few have attempted to characterize these cellular events under conditions similar to the native environment.To address this challenge,a three-dimensional(3D)multimodal analysis platform was developed for characterizing in vivo cellular dynamics in skin,which was then utilized to process in vivo wound healing data to demonstrate its applicability.Special attention is focused on in vivo biological parameters that are difficult to study with ex vivo analysis,including 3D cell tracking and techniques to connect biological information obtained from different imaging modalities.These results here open new possibilities for evaluating 3D cellular dynamics in vivo,and can potentially provide new tools for characterizing the skin microenvironment and pathologies in the future.展开更多
Multifocal multiphoton microscopy(MMM)has recently become an important tool in biomedicine for performing three-dimensional fastfluorescence imaging.Using various beamsplitting techniques,MMM splits the near-infrared ...Multifocal multiphoton microscopy(MMM)has recently become an important tool in biomedicine for performing three-dimensional fastfluorescence imaging.Using various beamsplitting techniques,MMM splits the near-infrared laser beam into multiple beamlets and produces a multifocal array on the sample for parallel multiphoton excitation and then recordsfluorescence signal from all foci simultaneously with an area array detector,which significantly improves the imaging speed of multiphoton microscopy and allows for high efficiency in use of the excitation light.In this paper,we discuss the features of several MMM setups using different beamsplitting devices,including a Nipkow spinning disk,a microlens array,a set of beamsplitting mirrors,or a diffractive optical element(DOE).In particular,we present our recent work on the development of an MMM using a spatial light modulator(SLM).展开更多
We report highly efficient avalanche multiphoton luminescence(MPL)from ordered-arrayed gold nanowires(NWs).The time-average excitation intensity I_(exc) is as low as 5.0-9.1 kW/cm^2.The intensity of avalanche MPL I_(M...We report highly efficient avalanche multiphoton luminescence(MPL)from ordered-arrayed gold nanowires(NWs).The time-average excitation intensity I_(exc) is as low as 5.0-9.1 kW/cm^2.The intensity of avalanche MPL I_(MPL) is about 10~4 times larger than that of three-photon luminescence,the slope ■logI_(MPL)/■logI_(exc) of avalanche MPL reaches as high as 18.3 and the corresponding polarization dependence of I_(MPL) has a form of cos^(50)■_p.The emission dynamics of avalanche MPL and three-photon luminesc...展开更多
Multiphoton excitations and nonlinear optical properties of exciton states in GaAs/AlxGa1-xAs coupled quantum well structure have been theoretically investigated under the influence of a time-varying high-intensity te...Multiphoton excitations and nonlinear optical properties of exciton states in GaAs/AlxGa1-xAs coupled quantum well structure have been theoretically investigated under the influence of a time-varying high-intensity terahertz(THz)laser field.Non-perturbative Floquet theory is employed to solve the time-dependent equation of motion for the laser-driven excitonic quantum well system.The response to the field parameters,such as intensity and frequency of the laser electric field on the state populations,can be used in various optical semiconductor device applications,such as photodetectors,sensors,all-optical switches,and terahertz emitters.展开更多
In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photo...In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photoelectron images are detected. The channel switching and above-threshold ionization(ATI) effect are also confirmed. The kinetic energy spectrum(KES) and the photoelectron angular distributions(PADs) are obtained through the anti-Abel transformation from the original images, and then three ionization channels are confirmed successfully according to the Freeman resonance effect in a relatively low laser intensity region. In the excitation process, the intermediate resonance Rydberg states are C^1 A 1(6 + 2 photons process), B^1 E(6 + 2 photons process) and C^1 A 1(7 + 2 photons process), respectively. At the same time, we also find that the photoelectron angular distributions are independent of laser intensity. In addition, the electrons produced by different processes interfere with each other and they can produce a spider-like structure. We also find ac-Stark movement according to the Stark-shift-induced resonance effect when the laser intensity is relatively high.展开更多
A single particle magneto-confined in a one-dimensional （1D） quantum wire experiences a harmonic potential, and imposing a sharply focused laser beam on an appropriate site shapes a δ potential. The theoretical inv...A single particle magneto-confined in a one-dimensional （1D） quantum wire experiences a harmonic potential, and imposing a sharply focused laser beam on an appropriate site shapes a δ potential. The theoretical investigation has demonstrated that for a sufficiently strong δ pulse the quantum motional stationary state of the particle is one of the eigenstates of the free harmonic oscillator, and it is determined by the site of the laser beam uniquely, namely a quantum state is admissible if and only if the laser site is one of its nodes. The numerical computation shows that all the nodes of the lower energy states with quantum numbers n ≤ 20, except the coordinate origin, are mutually different. So we can manipulate the multiphoton transitions between the quantum states by adjusting the position of the laser δ pulse and realize the transition from an unknown higher excitation state to a required lower energy state.展开更多
Using the numerical solution of the time-dependent SchrSdinger equation of a one-dimensional model atom in a two-colour laser field, we have investigated the effects of the potential models on coherent control of atom...Using the numerical solution of the time-dependent SchrSdinger equation of a one-dimensional model atom in a two-colour laser field, we have investigated the effects of the potential models on coherent control of atomic multiphoton ionization. It is found that the photoelectron spectra are obviously different for the long-range （Coulomb-like） and short-range （with no excited bound states） potential model atoms, which are produced by two-colour coherent control of atomic multiphoton ionization in a few laser cycles. Our results indicate that two-colour coherent control of atomic multiphoton ionization can be observed in simulations, depending on the choice of the model potentials.展开更多
This paper studies the multiphoton resonant ionization by two-colour laser pulses in the hydrogen atom by solving the time-dependent Schroedinger equation. By fixing the parameters of fundamental laser field and scann...This paper studies the multiphoton resonant ionization by two-colour laser pulses in the hydrogen atom by solving the time-dependent Schroedinger equation. By fixing the parameters of fundamental laser field and scanning the frequency of second laser field, it finds that the ionization probability shows several resonance peaks and is also much larger than the linear superposition of probabilities by applying two lasers separately. The enhancement of the ionization happens when the system is resonantly pumped to the excited states by absorbing two or more colour photons non-sequentially.展开更多
文摘Late-stage modification of complex molecules via site-selective hydrodefluorination is a challenging endeavor.The selective activation of carbon-fluorine(C-F) bonds in the presence of multiple C-F bonds is of importance in organic synthesis and drug discovery.Herein,we describe the activation of C-F bonds via multiphoton photoredox catalysis to selectively produces a series of hydrodefluorinated compounds by simply tuning the reaction conditions.Moreover,this protocol was successfully applied to the late-stage functionalization of different drug-derivatives and the corresponding mono-,di-,and tri-defluorinated products were obtained in good to excellent yields.A detailed mechanistic investigation provides insight into the unprecedented hydrodefluorination pathway.
基金the National Natural Science Foundation of China(52275294)the National Key Research and Development Program of China(2018YFA0703000).
文摘The designing and manufacturing of micro/nanoscale tools for delivery,diagnostic,and therapeutic are essential for their multiscale integration in the precision medicine field.Conventional three-dimensional(3D)printing approaches are not suitable for such kind of tools due to the accuracy limitation.Multiphoton polymerization(MPP)-based micro/nanomanufacturing is a noncontact,high-precision molding technology that has been widely used in the micro/nano field is a promising tool for micro/nanoscale related precision medicine.In this article the fundamentals of MPP-based technology and the required materials in precision medicine are overviewed.The biomedical applications in various scenarios are then summarized and categorized as delivery systems,microtissue modeling,surgery,and diagnosis.Finally,the existing challenges and future perspectives on MPP-based micro/nanomanufacturing for precision medicine are discussed,focusing on material design,process optimization,and practical applications to overcome its current limitations.
基金funded by the Science and Technology Research Program of Chongqing Municipal Education Commission(KJZD-K202301105,KJQN202201107)the Scienti¯c and Technological Transformative Program of Chongqing Banan District(KY202208161124020).
文摘Traumatic penumbra(TP)is a region with recoverable potential around the primary lesion of brain injury.Rapid and accurate imaging for identifying TP is essential for treating traumatic brain injury(TBI).In this study,we first established traumatic brain injuries(TBIs)in rats using a modified Feeney method,followed by label-free imaging of brain tissue sections with multiphoton fluorescence microscopy.The results showed that the technique effectively imaged normal and traumatic brain tissues,and revealed pathological features such as extracellular matrix changes,vascular cell proliferation,and intracellular edema in the traumatic penumbra.Compared with normal brain tissue,the extracellular matrix in the TP was sparse,cells were disorganized,and hyperplastic vascular cells emitted higher two-photon excited fluorescence(TPEF)signals.Our research demonstrates the potential of multiphoton fluorescence technology in the rapid diagnosis and therapeutic evaluation of TBI.
基金supported by the Ministry of Science,ICT and Future Planning(MSIP)through the National Research Foundation of Korea(NRF)(RS-2024-00450201)supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute(KHIDI),funded by the Ministry of Health and Welfare,Republic of Korea(HI22C1374).
文摘We developed an imaging technique combining two-photon computed super-resolution microscopy and suction-based stabilization to achieve the resolution of the single-cell level and organelles in vivo.To accomplish this,a conventional two-photon microscope was equipped with a 3D-printed holders,which stabilize the tissue surface within the focal plane of immersion objectives.Further computational image stabilization and noise reduction were applied,followed by superresolution radial fluctuations(SRRF)analysis,doubling image resolution,and enhancing signal-to-noise ratios for in vivo subcellular process investigation.Stabilization of<1μm was obtained by suction,and<25 nm were achieved by subsequent algorithmic image stabilization.A Mito-Dendra2 mouse model,expressing green fluorescent protein(GFP)in mitochondria,demonstrated the potential of long-term intravital subcellular imaging.In vivo mitochondrial fission and fusion,mitochondrial status migration,and the effects of alcohol consumption(modeled as an alcoholic liver disease)and berberine treatment on hepatocyte mitochondrial dynamics are directly observed intravitally.Suction-based stabilization in two-photon intravital imaging,coupled with computational super-resolution holds promise for advancing in vivo subcellular imaging studies.
基金Supported by Program for Changjiang Scholars and Innovative Research Team in University,No.IRT1115the National Natural Science Foundation of China,No.81271620+2 种基金the Natural Science Foundation for Distinguished Young Scholars of Fujian Province,No.2014J06016the Youth Scientific Research Foundation of Fujian Provincial Department of Health(2013-2-36)National Clinical Key Specialty Construction Project(General Surgery)
文摘AIM: To evaluate the feasibility of using multiphoton microscopy(MPM) to assess a tumor regression grading(TRG) system.METHODS: Fresh specimens from seven patients with colorectal carcinoma undergoing neoadjuvant radiochemotherapy at the Fujian Medical University Union Hospital were obtained immediately after proctectomy.Specimens were serially sectioned(10 μm thickness) and used for MPM or stained with hematoxylin and eosin for comparison.Sections were imaged by MPM using 810 nm excitation, and images were collected in two wavelength channels corresponding to second-harmonic generation(SHG) and two-photon excited fluorescence(TPEF) signals.The ratio of these signal intensities was used to distinguish fibrosis from normal mucosal and serosal tissues.RESULTS: TRG of specimens assessed by MPMwere in complete agreement with histologic grading performed by a consulting pathologist.SHG and TPEF images clearly revealed collagen fibers and fragmented elastic fibers in the muscularis propria specimens following neoadjuvant radiochemotherapy.Additionally, blood vessel hyperplasia was observed as thickening and fibrosis of the intima and media, which was accompanied by minimal inflammatory cell infiltration.Furthermore, the SHG/TPEF ratio in stromal fibrosis(4.15 ± 0.58) was significantly higher than those in the normal submucosal(2.31 ± 0.52) and serosal(1.47 ± 0.10) tissues(P < 0.001 for both).Analysis of emission spectra from cancerous tumor cells revealed two peaks corresponding to nicotinamide adenine dinucleotide hydrogen and flavin adenine dinucleotide signals; the ratio of these values was 1.19 ± 0.02, which is close to a normal metabolic state.CONCLUSION: MPM can be used to perform realtime diagnosis of tumor response after neoadjuvant treatment, and can be applied to evaluate TRG.
基金the National Natural Science Foundation of China under，教育部科学技术研究项目
文摘Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical multiphoton resonance spectra that can be compared with the experimental data. We also obtain the time evolution of the final state in different microwave fields.
基金support of the National Research Program of Genomic Medicine(NRPGM)of the National Science Council(NSC)in Taiwan.
文摘Multiphoton microscopy(MPM),with the advantages of improved penetration depth,decreased photo-damage,and optical sectioning capability,has become an indispensable tool for biomedical imaging.The combination of multiphoton fluorescence(MF)and second-harmonic generation(SHG)microscopy is particularly effective in imaging tissue structures of the ocular surface.This work is intended to be a review of advances that MPM has made in ophthalmic imaging.The MPM not only can be used for the label-free imaging of ocular structures,it can also be applied for investigating the morphological alterations in corneal pathologies,such as keratoconus,infected keratitis,and corneal scar.Furthermore,the corneal wound healing process after refractive surgical procedures such as conductive keratoplasty(CK)can also be studied with MPM.Finally,qualitative and quantitative SHG microscopy is effective for characterizing corneal thermal denaturation.With additional development,multiphoton imaging has the potential to be developed into an effective imaging technique for in vivo studies and clinical diagnosis in ophthalmology.
基金the National Natural Science Foundation of China under Grant Nos 11725417 and 11575027the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics under Grant No U1730449,and the Science Challenge Project under Grant No TZ2018005
文摘The elaborate energy and momentum spectra of ionized electrons from atoms in laser fields suggest that the ionization dynamics described by tunneling theory should be modified. Although great efforts have been carried out within semiclassical models, there are few discussions describing the multiphoton absorption process within a quantum framework. Comparing the results obtained with the time-dependent Schr?dinger equation(TDSE)and the Keldysh–Faisal–Reiss(KFR) theory, we study the nonperturbative effects of ionization dynamics beyond the KFR theory. The difference in momentum spectra between multiphoton and tunneling regimes is understood in a unified picture with virtual multiphoton absorption processes. For the multiphoton regime, the momentum spectra can be obtained by coherent interference of each periodic contribution. However, the interference of multiphoton absorption peaks will result in a complex structure of virtual multiphoton bands in the tunneling regime. It is shown that the virtual spectra will be almost continuous in the tunneling regime instead of the discrete levels found in the multiphoton regime. Finally, with a model combining the TDSE and the KFR theory,we try to understand the different effects of virtual multiphoton processes on ionization dynamics.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11044007,11164025,and 11064013)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos.20096203110001 and 20116203120001)the Foundation of Northwest Normal University,China (Grant No. NWNU-KJCXGC-03-62)
文摘We study the ionization probabilities of atoms by a short laser pulse with three different theoretical methods, i.e., the numerical solution of the time-dependent SchrSdinger equation （TDSE）, the Perelomov-Popov Terent＇ev （PPT） theory, and the Ammosov-Delone-Krainov （ADK） theory. Our results show that laser intensity dependent ionization probabilities of several atoms （i.e., H, He, and Ne） obtained from the PPT theory accord quite well with the TDSE results both in the multiphoton and tunneling ionization regimes, while the ADK results fit well to the TDSE data only in the tunneling ionization regime. Our calculations also show that laser intensity dependent ionization probabilities of a H atom at three different laser wavelengths of 600 nm, 800 nm, and 1200 nm obtained from the PPT theory are also in good agreement with those from the TDSE, while the ADK theory fails to give the wavelength dependence of ionization probability. Only when the laser wavelength is long enough, will the results of ADK be close to those of TDSE.
基金supported by National Key Research and Development Program of China (Grant No. 2019YFA0308300)the National Natural Science Foundation of China (Grant Nos. 12021004 and 61475055)。
文摘We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Schr ¨odinger equation. The photoelectron momentum distributions display many ring-like patterns for the three-photon ionization, which vary dramatically with the change of the laser wavelength. We show that the wavelength-dependent photoelectron energy spectrum can be used to effectively identify the resonant and nonresonant ionization pathways. We also find an abnormal ellipticity dependence of the electron yield for the(2+1) resonance-enhanced ionization via the 4d intermediate state, which is relevant to the two-photon excitation probability from the ground state to the 4d state.
文摘Multiphoton microscopy, relying on the simultaneous absorption of two or more photons by a fluorophore, has come to occupy a prominent place in modern biomedical research with its ability to allow real-time observation of a single cell and molecules in intact tissues. Multiphoton microscopy exhibits nonlinear optical contrast properties, which can make it possible to provide an exceptionally large depth penetration with less phototoxicity. This system becomes more and more an inspiring tool for a non-invasive imaging system to realize "optical biopsy" and to examine the functions of living cells. In this review, we briefly present the physical principles and properties of multiphoton microscopy as well as the current applications in biological fields. In addition, we address what we see as the future potential of multiphoton microscopy for gastroenterologic research.
基金supported by the National Natural Science Foundation of China(No.21627810)the Fundamental Research Funds for the Central Universities,Nankai University(No.63191523)。
文摘The infrared multiphoton dissociation(IRMPD)spectrum of the protonated heterodimer of Pro Phe H+,in the range of 2700-3700 cm^-1,has been obtained with a Fourier-transform ion cyclotron mass spectrometer combined with an IR OPO laser.The experimental spectrum shows one peak at 3565 cm^-1 corresponding to the free carboxyl O-H stretching vibration,and two broad peaks centered at 2935 and 3195 cm^-1.Theoretical calculations were performed on the level of M062 X/6-311++G(d,p).Results show that the most stable isomer is characterized by a charge-solvated structure in which the proton is bound to the unit of proline.Its predicted spectrum is in good agreement with the experimental one,although the coexistence of salt-bridged structures cannot be entirely excluded.
基金funded in part by grants from the National Institutes of Health(1R01CA213149,5R01EB023232)the National Science Foundation(CBET 18-41539).
文摘To date,numerous studies have been performed to elucidate the complex cellular dynamics in skin diseases,but few have attempted to characterize these cellular events under conditions similar to the native environment.To address this challenge,a three-dimensional(3D)multimodal analysis platform was developed for characterizing in vivo cellular dynamics in skin,which was then utilized to process in vivo wound healing data to demonstrate its applicability.Special attention is focused on in vivo biological parameters that are difficult to study with ex vivo analysis,including 3D cell tracking and techniques to connect biological information obtained from different imaging modalities.These results here open new possibilities for evaluating 3D cellular dynamics in vivo,and can potentially provide new tools for characterizing the skin microenvironment and pathologies in the future.
基金This work has been partially supported by NIH(SC COBRE P20RR021949 and Career Award 1k25hl088262-01)NSF(MRI CBET-0923311 and SC EPSCoR RII EPS-0903795 through SC GEAR program)+3 种基金The National Natural Science Foundation of China(31171372,61078067)Guangdong Province Science and Technology Project(2010B060300002)Shenzhen University Application Technology Development Project(201136,CXB201104220021A,JC201005250032A,200854)the Fundamental Research Funds for the Central Universities(K50510050006).
文摘Multifocal multiphoton microscopy(MMM)has recently become an important tool in biomedicine for performing three-dimensional fastfluorescence imaging.Using various beamsplitting techniques,MMM splits the near-infrared laser beam into multiple beamlets and produces a multifocal array on the sample for parallel multiphoton excitation and then recordsfluorescence signal from all foci simultaneously with an area array detector,which significantly improves the imaging speed of multiphoton microscopy and allows for high efficiency in use of the excitation light.In this paper,we discuss the features of several MMM setups using different beamsplitting devices,including a Nipkow spinning disk,a microlens array,a set of beamsplitting mirrors,or a diffractive optical element(DOE).In particular,we present our recent work on the development of an MMM using a spatial light modulator(SLM).
文摘We report highly efficient avalanche multiphoton luminescence(MPL)from ordered-arrayed gold nanowires(NWs).The time-average excitation intensity I_(exc) is as low as 5.0-9.1 kW/cm^2.The intensity of avalanche MPL I_(MPL) is about 10~4 times larger than that of three-photon luminescence,the slope ■logI_(MPL)/■logI_(exc) of avalanche MPL reaches as high as 18.3 and the corresponding polarization dependence of I_(MPL) has a form of cos^(50)■_p.The emission dynamics of avalanche MPL and three-photon luminesc...
文摘Multiphoton excitations and nonlinear optical properties of exciton states in GaAs/AlxGa1-xAs coupled quantum well structure have been theoretically investigated under the influence of a time-varying high-intensity terahertz(THz)laser field.Non-perturbative Floquet theory is employed to solve the time-dependent equation of motion for the laser-driven excitonic quantum well system.The response to the field parameters,such as intensity and frequency of the laser electric field on the state populations,can be used in various optical semiconductor device applications,such as photodetectors,sensors,all-optical switches,and terahertz emitters.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574116,11534004,10704028,and 11474123)
文摘In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photoelectron images are detected. The channel switching and above-threshold ionization(ATI) effect are also confirmed. The kinetic energy spectrum(KES) and the photoelectron angular distributions(PADs) are obtained through the anti-Abel transformation from the original images, and then three ionization channels are confirmed successfully according to the Freeman resonance effect in a relatively low laser intensity region. In the excitation process, the intermediate resonance Rydberg states are C^1 A 1(6 + 2 photons process), B^1 E(6 + 2 photons process) and C^1 A 1(7 + 2 photons process), respectively. At the same time, we also find that the photoelectron angular distributions are independent of laser intensity. In addition, the electrons produced by different processes interfere with each other and they can produce a spider-like structure. We also find ac-Stark movement according to the Stark-shift-induced resonance effect when the laser intensity is relatively high.
基金Project supported by the National Natural Science Foundation of China （Grant No 10575034）, and the Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics of China （Grant No T152504）.
文摘A single particle magneto-confined in a one-dimensional （1D） quantum wire experiences a harmonic potential, and imposing a sharply focused laser beam on an appropriate site shapes a δ potential. The theoretical investigation has demonstrated that for a sufficiently strong δ pulse the quantum motional stationary state of the particle is one of the eigenstates of the free harmonic oscillator, and it is determined by the site of the laser beam uniquely, namely a quantum state is admissible if and only if the laser site is one of its nodes. The numerical computation shows that all the nodes of the lower energy states with quantum numbers n ≤ 20, except the coordinate origin, are mutually different. So we can manipulate the multiphoton transitions between the quantum states by adjusting the position of the laser δ pulse and realize the transition from an unknown higher excitation state to a required lower energy state.
基金Project supported by the National Natural Science Foundation of China （Grant No 10674112） and the Young Teachers Foundation of Northwest Normal University （Grant No NWNU-QN-04-25）.
文摘Using the numerical solution of the time-dependent SchrSdinger equation of a one-dimensional model atom in a two-colour laser field, we have investigated the effects of the potential models on coherent control of atomic multiphoton ionization. It is found that the photoelectron spectra are obviously different for the long-range （Coulomb-like） and short-range （with no excited bound states） potential model atoms, which are produced by two-colour coherent control of atomic multiphoton ionization in a few laser cycles. Our results indicate that two-colour coherent control of atomic multiphoton ionization can be observed in simulations, depending on the choice of the model potentials.
基金supports by the Beijing Key Laboratory for Nano-Photonics and Nano-Structure
文摘This paper studies the multiphoton resonant ionization by two-colour laser pulses in the hydrogen atom by solving the time-dependent Schroedinger equation. By fixing the parameters of fundamental laser field and scanning the frequency of second laser field, it finds that the ionization probability shows several resonance peaks and is also much larger than the linear superposition of probabilities by applying two lasers separately. The enhancement of the ionization happens when the system is resonantly pumped to the excited states by absorbing two or more colour photons non-sequentially.
