Currently,laser-induced structural modifications in optical materials have been an active field of research.In this paper,we reported structural modifications in the bulk of sapphire due to picosecond(ps)laser filamen...Currently,laser-induced structural modifications in optical materials have been an active field of research.In this paper,we reported structural modifications in the bulk of sapphire due to picosecond(ps)laser filamentation and analyzed the ionization dynamics of the filamentation.Numerical simulations uncovered that the high-intensity ps laser pulses generate plasma through multi-photon and avalanche ionizations that leads to the creation of two distinct types of structural changes in the material.The experimental bulk modifications consist of a void like structures surrounded by cracks which are followed by a submicrometer filamentary track.By increasing laser energy,the length of the damage and filamentary track appeared to increase.In addition,the transverse diameter of the damage zone increased due to the electron plasma produced by avalanche ionizations,but no increase in the filamentary zone diameter was observed with increasing laser energy.展开更多
The transient dynamics of anisotropic properties of Ga As was systematically studied by polarization-dependent ultrafast time-resolved transient absorption.Our findings revealed that the anisotropy of reflectivity was...The transient dynamics of anisotropic properties of Ga As was systematically studied by polarization-dependent ultrafast time-resolved transient absorption.Our findings revealed that the anisotropy of reflectivity was enhanced in both pump-induced and probe-induced processes,suggesting an extraordinary resonance absorption of photon-phonon coupling(PPC)with intrinsic anisotropic characteristic in carrier relaxation,regardless of the concrete crystallinity and orientation of GaAs sample.The results,delivering in-depth cognition about the polarization-dependent ultrafast carrier dynamics,also proved the paramount importance of interaction between polarized laser and semiconductor.展开更多
Ultrafast laser filamentation results from the interaction of ultrafast laser with Kerr media.During filamentary propagation,the transparent medium is altered by numerous linear and nonlinear effects of ultrashort las...Ultrafast laser filamentation results from the interaction of ultrafast laser with Kerr media.During filamentary propagation,the transparent medium is altered by numerous linear and nonlinear effects of ultrashort laser pulses.Filamentation can cause material modification in solids through laser energy deposition and ionization processes,which creates a new opportunity for ultrafast laser processing of materials when combined with filamentary propagation characteristics,such as intensity champing and long propagation distance.This paper reviews the research on ultrafast laser filamentation in solids for micro-and nano-processing,including the fundamental physics,filamentation characteristics,and applications in solids for ultrafast laser filamentation-induced processing.Additionally highlighted are the difficulties and potential applications for solid-based filamentation-induced processing.展开更多
The self-mixing interferometry(SMI)technique is an emerging sensing technology in microscale particle classification.However,due to the nature of the SMI effect raised by a microscattering particle,the signal analysis...The self-mixing interferometry(SMI)technique is an emerging sensing technology in microscale particle classification.However,due to the nature of the SMI effect raised by a microscattering particle,the signal analysis suffers from many problems compared with a macro target,such as lower signal-to-noise ratio(SNR),short transit time,and time-varying modulation strength.Therefore,the particle sizing measurement resolution is much lower than the one in typical displacement measurements.To solve these problems,in this paper,first,a theoretical model of the phase variation of a singleparticle SMI signal burst is demonstrated in detail.The relationship between the phase variation and the particle size is investigated,which predicts that phase observation could be another alternative for particle detection.Second,combined with continuous wavelet transform and Hilbert transform,a novel phase-unwrapping algorithm is proposed.This algorithm can implement not only efficient individual burst extraction from the noisy raw signal,but also precise phase calculation for particle sizing.The measurement shows good accuracy over a range from 100 nm to 6μm with our algorithm,proving that our algorithm enables a simple and reliable quantitative particle characteristics retrieval and analysis methodology for microscale particle detection in biomedical or laser manufacturing fields.展开更多
Zirconia(ZrO_(2))ceramics have potential applications in the field of oral medicine owing to their desirable me-chanical properties,biocompatibility,chemical stability,and aesthetic properties.To realize clinical appl...Zirconia(ZrO_(2))ceramics have potential applications in the field of oral medicine owing to their desirable me-chanical properties,biocompatibility,chemical stability,and aesthetic properties.To realize clinical applications,ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics for all-ceramic dental implants were prepared using vat photopolymerization 3D printing technology,and their process optimization,microstructure,mechanics,tribology,and biological proper-ties were studied.The results indicate that when the sintering temperature and holding time are 1600℃and 3 h,respectively,the density of ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics reaches 98.79%,and its Vickers hardness,compressive strength,flexural strength,and fracture toughness also reach their maximum values.Furthermore,the in vitro sim-ulated oral environment wear tests showed that artificial saliva provides a lubricating effect on ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics and improves wear resistance.The biosafety of ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics was evaluated and ZrO_(2)(3Y)/Al_(2)O_(3)had no obvious cytotoxicity and promoted cell proliferation,growth,and adhesion.In addition,its surface has appropriate roughness and good wettability.In conclusion,ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics prepared by vat photopolymerization are promising biomaterials with broad application prospects in dental restoration.展开更多
The regeneration of the injured nerve and recovery of its function have brought attention in the medical field. Electrical stimulation(ES) can enhance the cellular biological behavior and has been widely studied in th...The regeneration of the injured nerve and recovery of its function have brought attention in the medical field. Electrical stimulation(ES) can enhance the cellular biological behavior and has been widely studied in the treatment of neurological diseases. Microfluidic technology can provide a cell culture platform with the well-controlled environment. Here a novel microfluidic/microelectrode composite microdevice was developed by embedding the microelectrodes to the microfluidic platform, in which microfluidics provided a controlled cell culture platform, and ES promoted the NSCs proliferation. We performed ES on rat neural stem cells(NSCs) to observe the effect on their growth, differentiation, proliferation, and preliminary explored the ES influence on cells in vitro. The results of immunofluorescence showed that ES had no significant effect on the NSCs specific expression, and the NSCs specific expression reached 98.9%± 0.4% after three days of ES. In addition, ES significantly promoted cell growth and the cell proliferation rate reached 49.41%. To conclude, the microfluidic/microelectrode composite microdevice can play a positive role in the nerve injury repair and fundamental research of neurological diseases.展开更多
基金National Natural Science Foundation of China(51575013,51275011)National Key R&D Program of China(2018 YFB1107500)
文摘Currently,laser-induced structural modifications in optical materials have been an active field of research.In this paper,we reported structural modifications in the bulk of sapphire due to picosecond(ps)laser filamentation and analyzed the ionization dynamics of the filamentation.Numerical simulations uncovered that the high-intensity ps laser pulses generate plasma through multi-photon and avalanche ionizations that leads to the creation of two distinct types of structural changes in the material.The experimental bulk modifications consist of a void like structures surrounded by cracks which are followed by a submicrometer filamentary track.By increasing laser energy,the length of the damage and filamentary track appeared to increase.In addition,the transverse diameter of the damage zone increased due to the electron plasma produced by avalanche ionizations,but no increase in the filamentary zone diameter was observed with increasing laser energy.
基金Project(51975017) supported by the National Natural Science Foundation of ChinaProject(KZ202110005012) supported by the Scientific Research Project of Beijing Educational Committee+1 种基金ChinaProject(2018YFB1107500) supported by the National Key R&D Program of China。
基金supported by the National Natural Science Foundation of China(Grant Nos.51875006 and 51705009)。
文摘The transient dynamics of anisotropic properties of Ga As was systematically studied by polarization-dependent ultrafast time-resolved transient absorption.Our findings revealed that the anisotropy of reflectivity was enhanced in both pump-induced and probe-induced processes,suggesting an extraordinary resonance absorption of photon-phonon coupling(PPC)with intrinsic anisotropic characteristic in carrier relaxation,regardless of the concrete crystallinity and orientation of GaAs sample.The results,delivering in-depth cognition about the polarization-dependent ultrafast carrier dynamics,also proved the paramount importance of interaction between polarized laser and semiconductor.
基金supported by the National Natural Science Foundation of China (no.51975017)the National Key R&D Program of China (no.2018YFB1107500)the Scientific Research Project of Beijing Educational Committee (no.KZ202110005012)。
文摘Ultrafast laser filamentation results from the interaction of ultrafast laser with Kerr media.During filamentary propagation,the transparent medium is altered by numerous linear and nonlinear effects of ultrashort laser pulses.Filamentation can cause material modification in solids through laser energy deposition and ionization processes,which creates a new opportunity for ultrafast laser processing of materials when combined with filamentary propagation characteristics,such as intensity champing and long propagation distance.This paper reviews the research on ultrafast laser filamentation in solids for micro-and nano-processing,including the fundamental physics,filamentation characteristics,and applications in solids for ultrafast laser filamentation-induced processing.Additionally highlighted are the difficulties and potential applications for solid-based filamentation-induced processing.
基金supported by the National Natural Science Foundation of China(Nos.61905005 and 52175375)the General Program of Science and Technology Development Project of Beijing Municipal Education Commission(No.KM202110005004)。
文摘The self-mixing interferometry(SMI)technique is an emerging sensing technology in microscale particle classification.However,due to the nature of the SMI effect raised by a microscattering particle,the signal analysis suffers from many problems compared with a macro target,such as lower signal-to-noise ratio(SNR),short transit time,and time-varying modulation strength.Therefore,the particle sizing measurement resolution is much lower than the one in typical displacement measurements.To solve these problems,in this paper,first,a theoretical model of the phase variation of a singleparticle SMI signal burst is demonstrated in detail.The relationship between the phase variation and the particle size is investigated,which predicts that phase observation could be another alternative for particle detection.Second,combined with continuous wavelet transform and Hilbert transform,a novel phase-unwrapping algorithm is proposed.This algorithm can implement not only efficient individual burst extraction from the noisy raw signal,but also precise phase calculation for particle sizing.The measurement shows good accuracy over a range from 100 nm to 6μm with our algorithm,proving that our algorithm enables a simple and reliable quantitative particle characteristics retrieval and analysis methodology for microscale particle detection in biomedical or laser manufacturing fields.
基金supported by Beijing Municipal Science and Tech-nology Project(Grant No.KM202010005003)General Program of Science and Technology Development Project of the Beijing Municipal Education Commission.
文摘Zirconia(ZrO_(2))ceramics have potential applications in the field of oral medicine owing to their desirable me-chanical properties,biocompatibility,chemical stability,and aesthetic properties.To realize clinical applications,ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics for all-ceramic dental implants were prepared using vat photopolymerization 3D printing technology,and their process optimization,microstructure,mechanics,tribology,and biological proper-ties were studied.The results indicate that when the sintering temperature and holding time are 1600℃and 3 h,respectively,the density of ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics reaches 98.79%,and its Vickers hardness,compressive strength,flexural strength,and fracture toughness also reach their maximum values.Furthermore,the in vitro sim-ulated oral environment wear tests showed that artificial saliva provides a lubricating effect on ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics and improves wear resistance.The biosafety of ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics was evaluated and ZrO_(2)(3Y)/Al_(2)O_(3)had no obvious cytotoxicity and promoted cell proliferation,growth,and adhesion.In addition,its surface has appropriate roughness and good wettability.In conclusion,ZrO_(2)(3Y)/Al_(2)O_(3)bioceramics prepared by vat photopolymerization are promising biomaterials with broad application prospects in dental restoration.
基金financially supported by the Key Scientific and Technological Projects of the Beijing Education Commission (No.KZ201910005009)。
文摘The regeneration of the injured nerve and recovery of its function have brought attention in the medical field. Electrical stimulation(ES) can enhance the cellular biological behavior and has been widely studied in the treatment of neurological diseases. Microfluidic technology can provide a cell culture platform with the well-controlled environment. Here a novel microfluidic/microelectrode composite microdevice was developed by embedding the microelectrodes to the microfluidic platform, in which microfluidics provided a controlled cell culture platform, and ES promoted the NSCs proliferation. We performed ES on rat neural stem cells(NSCs) to observe the effect on their growth, differentiation, proliferation, and preliminary explored the ES influence on cells in vitro. The results of immunofluorescence showed that ES had no significant effect on the NSCs specific expression, and the NSCs specific expression reached 98.9%± 0.4% after three days of ES. In addition, ES significantly promoted cell growth and the cell proliferation rate reached 49.41%. To conclude, the microfluidic/microelectrode composite microdevice can play a positive role in the nerve injury repair and fundamental research of neurological diseases.