Objective: To investigate the clinical efficacy of the cement-screw technique in repairing tibial plateau bone defects in total knee arthroplasty (TKA) recipients and summarize the preoperative prehabilitation strateg...Objective: To investigate the clinical efficacy of the cement-screw technique in repairing tibial plateau bone defects in total knee arthroplasty (TKA) recipients and summarize the preoperative prehabilitation strategies for such surgeries. Methods: A total of 33 TKA recipients (45 knees) in our department underwent repair of unilateral or bilateral tibial defects using the cement-screw technique. The subjects were divided into two groups based on the differences in preoperative interventions. The control group received routine preoperative health education according to the consensus, while the observation group received instructive and standardized prehabilitation exercises for four weeks in addition to the routine education. Scale scores, intraoperative parameters, and postoperative recovery indicators were recorded at different time pointsand subjected to statistical analysis for intra-group and inter-group differences. All subjects underwent long-term follow-up for at least 24 months. Results: Within each group at different time points, there were statistically significant differences in VAS, ROM, and HSS scores (p Conclusions: Cement-screw technique for repairing tibial plateau bone defects in TKA recipients can significantly relieve pain, and improve joint function. Prehabilitation can improve preoperative rehabilitation reserves in these patients, accelerate postoperative recovery, and contribute to better short-term clinical outcomes.展开更多
The Western Subarctic Gyre(WSG)is one of the two gyre-systems in the subarctic North Pacific known for high nutrient and low-chlorophyll waters.However,the bacterioplankton in marine water of this area,either in terms...The Western Subarctic Gyre(WSG)is one of the two gyre-systems in the subarctic North Pacific known for high nutrient and low-chlorophyll waters.However,the bacterioplankton in marine water of this area,either in terms of the taxonomic composition or functional structure,remains relatively unexplored.A total of 22 sampling sites from two water layers(surface water,SW and 50-m layer water,FW)were collected in this area.The physiochemical parameters of waters,Synechococcus,and bacterial density,as well as the bacterioplankton community composition and distribution pattern,were analyzed.The nutrient concentrations of DIN,DIP,and DSi,Chl-a concentration,and the average abundance of heterobacteria in FW were higher than those in SW.However,temperature and the average abundance of Synechococcus and pico-eukaryotes were higher in SW.A total of 3269 OTUs were assigned,and 2123OTUs were commonly shared;moreover,similar alpha diversity patterns were observed in both SW and FW.The bacterioplankton community showed significantly obvious correlation with salinity,DIP,DIN,and Chl a in both SW and FW.Proteobacteria,Cyanobacteria,Bacteroidota,Actinobacteriota,and Firmicutes were the main phyla while Synechococcus_CC9902,Psychrobacter,and Sulfitobacter were the dominant genera in each sampling site.Most correlations that happened between the OTUs in the cooccurrence network were positive and inter-module.Higher edges and graph density were found in SW,indicating that more correlations occurred,and the community was more complex in SW.This study provided novel knowledge on the bacterioplankton community structure and the correlation characteristics in WSG.展开更多
According to the practices in the field of ecological compensation for water conservancy in Zhejiang Province,this article points out the problems and shortcomings in the ecological compensation mechanism for water co...According to the practices in the field of ecological compensation for water conservancy in Zhejiang Province,this article points out the problems and shortcomings in the ecological compensation mechanism for water conservancy,analyzes the obstacles to the effective running of the mechanism,explains the internal reasons for the implementation process of the mechanism,and discusses the countermeasures for developing this mechanism.展开更多
A continuous hot embossing method is reported in this paper. The continuous means that the extruder and the hot embossing equipment is used in series, the polymer film is embossed after extrusion immediately. The basi...A continuous hot embossing method is reported in this paper. The continuous means that the extruder and the hot embossing equipment is used in series, the polymer film is embossed after extrusion immediately. The basic principle of this method, the key design point and the corresponding operate process of the embossing equipment is described in this paper. The polymer diffuser with micro-lens matrix on its surface is designed and the optical properties are simulated. Then, the diffuser is fabricated by the embossing equipment. The optical properties of the diffuser are tested and compared with the results of the simulation to verify the reproducibility of the equipment. By this method, the diffuser with large area can be fabricated with high precision of graphic replication, high efficiency and low cost.展开更多
基于二维纳米材料MXene的导电水凝胶,已成为柔性可穿戴传感器领域的非常有前景的材料.在这些应用中,制备同时具有高韧性、超弹性、低滞后性、自粘性和多种感官功能的凝胶至关重要.然而,MXene纳米片在水介质中容易重新堆积,不可避免会被...基于二维纳米材料MXene的导电水凝胶,已成为柔性可穿戴传感器领域的非常有前景的材料.在这些应用中,制备同时具有高韧性、超弹性、低滞后性、自粘性和多种感官功能的凝胶至关重要.然而,MXene纳米片在水介质中容易重新堆积,不可避免会被氧化,以及MXene和凝胶网络之间薄弱的界面结合等问题,使得MXene基水凝胶几乎不可能实现上述多种性能.在文中,我们将明胶改性的MXene引入到聚丙烯酰胺(PAAm)水凝胶中,制备了一种导电的MXene-复合聚合物(MCP)水凝胶,用于制造多功能传感器.明胶的存在不仅通过形成一个保护鞘大大改善了MXene纳米片的稳定性,而且作为分子胶还在很大程度上增强了MXene和水凝胶网络之间的界面相互作用.因此,MCP水凝胶表现出高强度(430 k Pa)、显著的可拉伸性(1100%)、低滞后性(在500%的循环拉伸下滞后率<10%)和良好的可重复粘附性.所得的基于MCP水凝胶的多功能传感器显示出高应变灵敏度,工作范围大(GF=8.83,最高1000%),实现了对各种人体运动的检测.此外,所制备的传感器还具有卓越的热敏能力(1.110/℃),可用于测量体温.这一策略为设计高性能MXene基水凝胶提供了新的思路.展开更多
We demonstrate an ultra-broadband high temporal contrast infrared laser source based on cascaded optical parametric amplification,hollow-core fiber(HCF)and second harmonic generation processes.In this setup,the spectr...We demonstrate an ultra-broadband high temporal contrast infrared laser source based on cascaded optical parametric amplification,hollow-core fiber(HCF)and second harmonic generation processes.In this setup,the spectrum of an approximately 1.8μm laser pulse has near 1μm full bandwidth by employing an argon gas-filled HCF.Subsequently,after frequency doubling with cascaded crystals and dispersion compensation by a fused silica wedge pair,9.6 fs(~3cycles)and 150μJ pulses centered at 910 nm with full bandwidth of over 300 nm can be generated.The energy stability of the output laser pulse is excellent with 0.8%(root mean square)over 20 min,and the temporal contrast is>10^(12)at-10 ps before the main pulse.The excellent temporal and spatial characteristics and stability make this laser able to be used as a good seed source for ultra-intense and ultrafast laser systems.展开更多
The development of high-intensity ultrafast laser facilities provides the possibility to create novel physical phenomena and matter states.The timing fluctuation of the laser pulses is crucial for pump–probe experime...The development of high-intensity ultrafast laser facilities provides the possibility to create novel physical phenomena and matter states.The timing fluctuation of the laser pulses is crucial for pump–probe experiments,which is one of the vital means to observe the ultrafast dynamics driven by intense laser pulses.In this paper,we demonstrate the timing fluctuation characterization and control of the front end of a 100-PW laser that is composed of a high-contrast optical parametric amplifier(seed)and a 200-TW optical parametric chirped pulse amplifier(preamplifier).By combining the timing jitter measurement with a feedback system,the laser seed and preamplifier are synchronized to the reference with timing fluctuations of 1.82 and 4.48 fs,respectively.The timing system will be a key prerequisite for the stable operation of 100-PW laser facilities and provide the basis for potential pump–probe experiments performed on the laser.展开更多
In this Letter, we experimentally explore the pulse-contrast degradation caused by surface reflection in optical parameter chirped-pulse amplification. Different pump-to-signal conversion efficiencies and post-pulses ...In this Letter, we experimentally explore the pulse-contrast degradation caused by surface reflection in optical parameter chirped-pulse amplification. Different pump-to-signal conversion efficiencies and post-pulses with different intensities are obtained by changing the seed-pulse or pump-pulse energy and inserting etalons with different reflection coefficients, respectively. The contrast measurements show that the generated first pre-pulse intensity is proportional to the product of the surface reflection intensity ratio and the square of the pump-to-signal conversion efficiency.展开更多
Lithium sulfide(Li_(2)S)is a promising cathode for a practical lithium-sulfur battery as it can be coupled with various safe lithium-free anodes.However,the high activation potential(>3.5 V)together with the shuttl...Lithium sulfide(Li_(2)S)is a promising cathode for a practical lithium-sulfur battery as it can be coupled with various safe lithium-free anodes.However,the high activation potential(>3.5 V)together with the shuttling of lithium polysulfides(LiPSs)bottleneck its practical uses.We are trying to present a catalysis solution to solve both problems simultaneously,specially with twinborn heterostructure to shoot off the trouble in interfacial contact between two solids,catalyst and Li_(2)S.As a typical example,a Co9S8/Li_(2)S heterostructure is reported here as a novel self-catalytic cathode through a co-recrystallization followed by a one-step carbothermic conversion.Co9S8 as the catalyst effectively lowers the Li_(2)S activation potential(<2.4 V)due to fully integrated and contacted interfaces and consistently promotes the conversion of LiPSs to suppress the shuttling.The obtained freestanding cathode of Co9S8/Li_(2)S heterostructures encapsulated in three-dimensional graphene shows a high capacity,reaching 92.6%of Li_(2)S theoretical capacity,high rate performance(739 mAh g1 at 2 C),and a low capacity fading(0.039%per cycle at 1 C over 900 cycles).Even under a high Li_(2)S loading of 12 mg cm^(-2)and a low E/S ratio of 5μL mgLi_(2)S^(-1),86%of theoretical capacity can be utilized.展开更多
We report on a vortex laser chirped-pulse amplification(CPA)system that delivers pulses with a peak power of 45 TW.A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplif...We report on a vortex laser chirped-pulse amplification(CPA)system that delivers pulses with a peak power of 45 TW.A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplification scheme.Compared with other schemes of strong-field vortex generation with high energy flux but narrowband vortex-converting elements at the end of the laser,an important advantage of our scheme is that we can use a broadband but size-limited q-plate to realize broadband mode-converting in the front end of the CPA system,and achieve high-power amplification with a series of amplifiers.This method is low cost and can be easily implemented in an existing laser system.The results have verified the feasibility to obtain terawatt and even petawatt vortex laser amplification by a CPA system,which has important potential applications in strong-field laser physics,for example,generation of vortex particle beams with orbital angular momentum,fast ignition for inertial confinement fusion and simulation of the extreme astrophysical environment.展开更多
Here,we report the recent progress on the front end developed for the 100 PW-class laser facility.Using 3 stages of optical parametric chirped-pulse amplification(OPCPA)based on lithium triborate(LBO)crystals,we reali...Here,we report the recent progress on the front end developed for the 100 PW-class laser facility.Using 3 stages of optical parametric chirped-pulse amplification(OPCPA)based on lithium triborate(LBO)crystals,we realized a 5.26 J/0.1 Hz amplified output with a bandwidth over 200 nm near the center wavelength of 925 nm.After the compressor,we obtained a pulse duration of 13.4 fs.As the compression efficiency reached 67%,this OPCPA front end could potentially support a peak power of 263 TW at a repetition rate of 0.1 Hz.To the best of our knowledge,among all the 100 TW-level OPCPA systems,it shows the widest spectral width,the shortest pulse duration,and it is also the first OPCPA system working at a repetition-rate mode.展开更多
Degradation of a metallic film under harsh thermal-mechanical-electrical coupling field conditions determines its service temperature and lifetime.In this work,the self-heating degradation behaviors of Pt thin films a...Degradation of a metallic film under harsh thermal-mechanical-electrical coupling field conditions determines its service temperature and lifetime.In this work,the self-heating degradation behaviors of Pt thin films above 1000℃were studied in situ by TEM at the nanoscale.The Pt films degraded mainly through void nucleation and growth on the Pt-SiN_(x)interface.Voids preferentially formed at the grain boundary and triple junction intersections with the interface.At temperatures above 1040℃,the voids nucleated at both the grain boundaries and inside the Pt grains.A stress simulation of the suspended membrane suggests the existence of local tensile stress in the Pt film,which promotes the nucleation of voids at the Pt-Si Nxinterface.The grain-boundary-dominated mass transportation renders the voids grow preferentially at GBs and triple junctions in a Pt film.Additionally,under the influence of an applied current,the voids that nucleated inside Pt grains grew to a large size and accelerated the degradation of the Pt film.展开更多
We demonstrate a high-contrast, joule-level Nd:glass laser system operating at 0.5 Hz repetition rate based on a double chirped pulse amplification(CPA) scheme. By injecting high-contrast, high-energy seed pulses into...We demonstrate a high-contrast, joule-level Nd:glass laser system operating at 0.5 Hz repetition rate based on a double chirped pulse amplification(CPA) scheme. By injecting high-contrast, high-energy seed pulses into the Nd:glass CPA stage, the pulse energy is amplified to 1.9 J through two optical parametric CPA stages and two Nd:glass amplifiers. The temporal contrast of compressed pulse is measured down to the level of 10^(-8)at tens of ps, and 10^(-10) near 200 ps before the main pulse, respectively.展开更多
We report dispersion management based on a mismatched-grating compressor for a 100 PW level laser,which utilizes optical parametric chirped pulse amplification and also features large chirped pulse duration and an ult...We report dispersion management based on a mismatched-grating compressor for a 100 PW level laser,which utilizes optical parametric chirped pulse amplification and also features large chirped pulse duration and an ultra-broadband spectrum.The numerical calculation indicates that amplified pulses with 4 ns chirped pulse duration and 210 nm spectral bandwidth can be directly compressed to sub-13 fs,which is close to the Fourier-transform limit(FTL).More importantly,the tolerances of the mismatched-grating compressor to the misalignment of the stretcher,the error of the desired grating groove density and the variation of material dispersion are comprehensively analyzed,which is crucially important for its practical application.The results demonstrate that good tolerances and near-FTL compressed pulses can be achieved simultaneously,just by keeping a balance between the residual second-,third-and fourth-order dispersions in the laser system.This work can offer a meaningful guideline for the design and construction of 100 PW level lasers.展开更多
The traditional intrusion detection system has the problem of high false positive rate and false negative rate.This paper deeply analyzes the differences of statistical features between single-flow and multi-flow on t...The traditional intrusion detection system has the problem of high false positive rate and false negative rate.This paper deeply analyzes the differences of statistical features between single-flow and multi-flow on the database network,and presents a group of features that are easy to acquire and can be used to detect the anomaly in database network efficiently.By applying this group of features in Fisher algorithm for anomaly detection,the false positive rate and false negative rate are dramatically reduced.Simultaneously,the model made by using the group of features has the advantages of low algorithm complexity,good detection result and strong generalization ability.Experimental results show that there is higher accuracy when using the features of single-flow and multiflow to construct the anomaly detection model than only using single-flow features.展开更多
文摘Objective: To investigate the clinical efficacy of the cement-screw technique in repairing tibial plateau bone defects in total knee arthroplasty (TKA) recipients and summarize the preoperative prehabilitation strategies for such surgeries. Methods: A total of 33 TKA recipients (45 knees) in our department underwent repair of unilateral or bilateral tibial defects using the cement-screw technique. The subjects were divided into two groups based on the differences in preoperative interventions. The control group received routine preoperative health education according to the consensus, while the observation group received instructive and standardized prehabilitation exercises for four weeks in addition to the routine education. Scale scores, intraoperative parameters, and postoperative recovery indicators were recorded at different time pointsand subjected to statistical analysis for intra-group and inter-group differences. All subjects underwent long-term follow-up for at least 24 months. Results: Within each group at different time points, there were statistically significant differences in VAS, ROM, and HSS scores (p Conclusions: Cement-screw technique for repairing tibial plateau bone defects in TKA recipients can significantly relieve pain, and improve joint function. Prehabilitation can improve preoperative rehabilitation reserves in these patients, accelerate postoperative recovery, and contribute to better short-term clinical outcomes.
基金Supported by the National Key Research and Development Program of China(No.2019YFD0901401)the Natural Science Foundation of Shandong Province(No.ZR202102280248)+1 种基金the National Natural Science Foundation of China(No.81900630)the Outstanding Youth Project of Yunnan Provincial Department of Science and Technology(No.2019F1019)。
文摘The Western Subarctic Gyre(WSG)is one of the two gyre-systems in the subarctic North Pacific known for high nutrient and low-chlorophyll waters.However,the bacterioplankton in marine water of this area,either in terms of the taxonomic composition or functional structure,remains relatively unexplored.A total of 22 sampling sites from two water layers(surface water,SW and 50-m layer water,FW)were collected in this area.The physiochemical parameters of waters,Synechococcus,and bacterial density,as well as the bacterioplankton community composition and distribution pattern,were analyzed.The nutrient concentrations of DIN,DIP,and DSi,Chl-a concentration,and the average abundance of heterobacteria in FW were higher than those in SW.However,temperature and the average abundance of Synechococcus and pico-eukaryotes were higher in SW.A total of 3269 OTUs were assigned,and 2123OTUs were commonly shared;moreover,similar alpha diversity patterns were observed in both SW and FW.The bacterioplankton community showed significantly obvious correlation with salinity,DIP,DIN,and Chl a in both SW and FW.Proteobacteria,Cyanobacteria,Bacteroidota,Actinobacteriota,and Firmicutes were the main phyla while Synechococcus_CC9902,Psychrobacter,and Sulfitobacter were the dominant genera in each sampling site.Most correlations that happened between the OTUs in the cooccurrence network were positive and inter-module.Higher edges and graph density were found in SW,indicating that more correlations occurred,and the community was more complex in SW.This study provided novel knowledge on the bacterioplankton community structure and the correlation characteristics in WSG.
基金Supported by Zhejiang Social Sciences Research Project in 2011(2011B051)Hangzhou Philosophy and Social Science Planning Project in2012(B12YJ15)
文摘According to the practices in the field of ecological compensation for water conservancy in Zhejiang Province,this article points out the problems and shortcomings in the ecological compensation mechanism for water conservancy,analyzes the obstacles to the effective running of the mechanism,explains the internal reasons for the implementation process of the mechanism,and discusses the countermeasures for developing this mechanism.
文摘A continuous hot embossing method is reported in this paper. The continuous means that the extruder and the hot embossing equipment is used in series, the polymer film is embossed after extrusion immediately. The basic principle of this method, the key design point and the corresponding operate process of the embossing equipment is described in this paper. The polymer diffuser with micro-lens matrix on its surface is designed and the optical properties are simulated. Then, the diffuser is fabricated by the embossing equipment. The optical properties of the diffuser are tested and compared with the results of the simulation to verify the reproducibility of the equipment. By this method, the diffuser with large area can be fabricated with high precision of graphic replication, high efficiency and low cost.
基金supported by the National Natural Science Foundation of China(22102139,21872119,and 22072127)the Natural Science Foundation of Hebei Province(B2021203001 and B2021203016)+1 种基金the Science and Technology Project of Hebei Education Department(ZD2022147)the Special Project for Local Science and Technology Development Guided by the Central Government of China(216Z1301G and 226Z1401G)。
文摘基于二维纳米材料MXene的导电水凝胶,已成为柔性可穿戴传感器领域的非常有前景的材料.在这些应用中,制备同时具有高韧性、超弹性、低滞后性、自粘性和多种感官功能的凝胶至关重要.然而,MXene纳米片在水介质中容易重新堆积,不可避免会被氧化,以及MXene和凝胶网络之间薄弱的界面结合等问题,使得MXene基水凝胶几乎不可能实现上述多种性能.在文中,我们将明胶改性的MXene引入到聚丙烯酰胺(PAAm)水凝胶中,制备了一种导电的MXene-复合聚合物(MCP)水凝胶,用于制造多功能传感器.明胶的存在不仅通过形成一个保护鞘大大改善了MXene纳米片的稳定性,而且作为分子胶还在很大程度上增强了MXene和水凝胶网络之间的界面相互作用.因此,MCP水凝胶表现出高强度(430 k Pa)、显著的可拉伸性(1100%)、低滞后性(在500%的循环拉伸下滞后率<10%)和良好的可重复粘附性.所得的基于MCP水凝胶的多功能传感器显示出高应变灵敏度,工作范围大(GF=8.83,最高1000%),实现了对各种人体运动的检测.此外,所制备的传感器还具有卓越的热敏能力(1.110/℃),可用于测量体温.这一策略为设计高性能MXene基水凝胶提供了新的思路.
基金supported by the National Key R&D Program of China(2017YFE0123700)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB1603)+3 种基金the National Natural Science Foundation of China(61925507,62075227,12004402,61635012)the Program of Shanghai Academic/Technology Research Leader(18XD1404200)the Shanghai Municipal Science and Technology Major Project(2017SHZDZX02)the Youth Innovation Promotion Association CAS(2020248)
文摘We demonstrate an ultra-broadband high temporal contrast infrared laser source based on cascaded optical parametric amplification,hollow-core fiber(HCF)and second harmonic generation processes.In this setup,the spectrum of an approximately 1.8μm laser pulse has near 1μm full bandwidth by employing an argon gas-filled HCF.Subsequently,after frequency doubling with cascaded crystals and dispersion compensation by a fused silica wedge pair,9.6 fs(~3cycles)and 150μJ pulses centered at 910 nm with full bandwidth of over 300 nm can be generated.The energy stability of the output laser pulse is excellent with 0.8%(root mean square)over 20 min,and the temporal contrast is>10^(12)at-10 ps before the main pulse.The excellent temporal and spatial characteristics and stability make this laser able to be used as a good seed source for ultra-intense and ultrafast laser systems.
基金supported by the Shanghai High Repetition Rate XFEL and Extreme Light Facility (SHINE) projectthe National Natural Science Foundation of China (62105346)+2 种基金the CAS Project for Young Scientists in Basic Research(YSBR-059)the 100 Talents Program of CASthe Basic Research Project of the Shanghai Science and Technology Innovation Action Plan (20JC1416000)
文摘The development of high-intensity ultrafast laser facilities provides the possibility to create novel physical phenomena and matter states.The timing fluctuation of the laser pulses is crucial for pump–probe experiments,which is one of the vital means to observe the ultrafast dynamics driven by intense laser pulses.In this paper,we demonstrate the timing fluctuation characterization and control of the front end of a 100-PW laser that is composed of a high-contrast optical parametric amplifier(seed)and a 200-TW optical parametric chirped pulse amplifier(preamplifier).By combining the timing jitter measurement with a feedback system,the laser seed and preamplifier are synchronized to the reference with timing fluctuations of 1.82 and 4.48 fs,respectively.The timing system will be a key prerequisite for the stable operation of 100-PW laser facilities and provide the basis for potential pump–probe experiments performed on the laser.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB1603)the International S&T Cooperation Program of China(No.2016YFE0119300)the National Natural Science Foundation of China(NSFC)(Nos.61521093 and 61505234)
文摘In this Letter, we experimentally explore the pulse-contrast degradation caused by surface reflection in optical parameter chirped-pulse amplification. Different pump-to-signal conversion efficiencies and post-pulses with different intensities are obtained by changing the seed-pulse or pump-pulse energy and inserting etalons with different reflection coefficients, respectively. The contrast measurements show that the generated first pre-pulse intensity is proportional to the product of the surface reflection intensity ratio and the square of the pump-to-signal conversion efficiency.
基金National Key Research and Development Program of China,Grant/Award Numbers:2018YFE0124500,2021YFF0500600National Natural Science Foundation of China,Grant/Award Numbers:52022041,51932005+1 种基金The Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program,Grant/Award Number:2017BT01N111Shenzhen Basic Research Project,Grant/Award Number:JCYJ20180508152037520。
文摘Lithium sulfide(Li_(2)S)is a promising cathode for a practical lithium-sulfur battery as it can be coupled with various safe lithium-free anodes.However,the high activation potential(>3.5 V)together with the shuttling of lithium polysulfides(LiPSs)bottleneck its practical uses.We are trying to present a catalysis solution to solve both problems simultaneously,specially with twinborn heterostructure to shoot off the trouble in interfacial contact between two solids,catalyst and Li_(2)S.As a typical example,a Co9S8/Li_(2)S heterostructure is reported here as a novel self-catalytic cathode through a co-recrystallization followed by a one-step carbothermic conversion.Co9S8 as the catalyst effectively lowers the Li_(2)S activation potential(<2.4 V)due to fully integrated and contacted interfaces and consistently promotes the conversion of LiPSs to suppress the shuttling.The obtained freestanding cathode of Co9S8/Li_(2)S heterostructures encapsulated in three-dimensional graphene shows a high capacity,reaching 92.6%of Li_(2)S theoretical capacity,high rate performance(739 mAh g1 at 2 C),and a low capacity fading(0.039%per cycle at 1 C over 900 cycles).Even under a high Li_(2)S loading of 12 mg cm^(-2)and a low E/S ratio of 5μL mgLi_(2)S^(-1),86%of theoretical capacity can be utilized.
基金supported by the National Natural Science Foundation of China(Nos.92050203,61925507,12174264,12004261,62075138,and 61827815)the Natural Science Foundation of Guangdong Province(Nos.2021A1515011909 and 2022A1515011457)the Shenzhen Fundamental Research Projects(Nos.JCYJ20200109105606426,JCYJ20190808164007485,JCYJ20190808121817100,JCYJ20190808143419622,and JCYJ20190808115601653).
文摘We report on a vortex laser chirped-pulse amplification(CPA)system that delivers pulses with a peak power of 45 TW.A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplification scheme.Compared with other schemes of strong-field vortex generation with high energy flux but narrowband vortex-converting elements at the end of the laser,an important advantage of our scheme is that we can use a broadband but size-limited q-plate to realize broadband mode-converting in the front end of the CPA system,and achieve high-power amplification with a series of amplifiers.This method is low cost and can be easily implemented in an existing laser system.The results have verified the feasibility to obtain terawatt and even petawatt vortex laser amplification by a CPA system,which has important potential applications in strong-field laser physics,for example,generation of vortex particle beams with orbital angular momentum,fast ignition for inertial confinement fusion and simulation of the extreme astrophysical environment.
基金Shanghai Municipal Science and Technology Major Project(2017SHZDZX02)Natural Science Foundation of Shanghai(20ZR1464600)+5 种基金This work is funded by the National Key R&D Program of China(2017YFE0123700)Program of Shanghai Academic/Technology Research Leader(18XD1404200)and International Partnership Program of Chinese Academy of Sciences(181231KYSB20200040)Shanghai Sailing Program(19YF1453100)National Natural Science Foundation of China(61925507)Youth Innovation Promotion Association of the Chinese Academy of Sciences The Strategic Priority Research Program of the Chinese Academy of Sciences(XDB1603)。
文摘Here,we report the recent progress on the front end developed for the 100 PW-class laser facility.Using 3 stages of optical parametric chirped-pulse amplification(OPCPA)based on lithium triborate(LBO)crystals,we realized a 5.26 J/0.1 Hz amplified output with a bandwidth over 200 nm near the center wavelength of 925 nm.After the compressor,we obtained a pulse duration of 13.4 fs.As the compression efficiency reached 67%,this OPCPA front end could potentially support a peak power of 263 TW at a repetition rate of 0.1 Hz.To the best of our knowledge,among all the 100 TW-level OPCPA systems,it shows the widest spectral width,the shortest pulse duration,and it is also the first OPCPA system working at a repetition-rate mode.
基金financially supported by the Basic Science Center Program for Multiphase Evolution in Hyper-gravity of the National Natural Science Foundation of China(51988101)NSFC Programs(Nos.52071003,91860202,11604006)+3 种基金the Beijing Municipal Education Commission Project(Nos.PXM2020014204000021 and PXM201901420400032)the Beijing Outstanding Young Scientists Projects(No.BJJWZYJH01201910005018)the Beijing Natural Science Foundation(No.Z180014)the“111 Project(No.DB18015)。
文摘Degradation of a metallic film under harsh thermal-mechanical-electrical coupling field conditions determines its service temperature and lifetime.In this work,the self-heating degradation behaviors of Pt thin films above 1000℃were studied in situ by TEM at the nanoscale.The Pt films degraded mainly through void nucleation and growth on the Pt-SiN_(x)interface.Voids preferentially formed at the grain boundary and triple junction intersections with the interface.At temperatures above 1040℃,the voids nucleated at both the grain boundaries and inside the Pt grains.A stress simulation of the suspended membrane suggests the existence of local tensile stress in the Pt film,which promotes the nucleation of voids at the Pt-Si Nxinterface.The grain-boundary-dominated mass transportation renders the voids grow preferentially at GBs and triple junctions in a Pt film.Additionally,under the influence of an applied current,the voids that nucleated inside Pt grains grew to a large size and accelerated the degradation of the Pt film.
文摘We demonstrate a high-contrast, joule-level Nd:glass laser system operating at 0.5 Hz repetition rate based on a double chirped pulse amplification(CPA) scheme. By injecting high-contrast, high-energy seed pulses into the Nd:glass CPA stage, the pulse energy is amplified to 1.9 J through two optical parametric CPA stages and two Nd:glass amplifiers. The temporal contrast of compressed pulse is measured down to the level of 10^(-8)at tens of ps, and 10^(-10) near 200 ps before the main pulse, respectively.
基金supported by the National Natural Science Foundation of China (61925507)National Key R&D Program of China (2017YFE0123700)+6 种基金Strategic Priority Research Program of Chinese Academy of Sciences (XDB1603)Shanghai Municipal Science and Technology Major Project (2017SHZDZX02)Shanghai Natural Science Foundation (20ZR1464600)Program of Shanghai Academic/Technology Research Leader (18XD1404200)Shanghai Sailing Program (21YF1453800)International Partnership Program of Chinese Academy of Sciences (181231KYSB20200040)Youth Innovation Promotion Association of CAS。
文摘We report dispersion management based on a mismatched-grating compressor for a 100 PW level laser,which utilizes optical parametric chirped pulse amplification and also features large chirped pulse duration and an ultra-broadband spectrum.The numerical calculation indicates that amplified pulses with 4 ns chirped pulse duration and 210 nm spectral bandwidth can be directly compressed to sub-13 fs,which is close to the Fourier-transform limit(FTL).More importantly,the tolerances of the mismatched-grating compressor to the misalignment of the stretcher,the error of the desired grating groove density and the variation of material dispersion are comprehensively analyzed,which is crucially important for its practical application.The results demonstrate that good tolerances and near-FTL compressed pulses can be achieved simultaneously,just by keeping a balance between the residual second-,third-and fourth-order dispersions in the laser system.This work can offer a meaningful guideline for the design and construction of 100 PW level lasers.
基金supported by the Key Project in the National Science and Technology Pillar Program (No.2008BAH37B04)the 111 Project (No.B08004).
文摘The traditional intrusion detection system has the problem of high false positive rate and false negative rate.This paper deeply analyzes the differences of statistical features between single-flow and multi-flow on the database network,and presents a group of features that are easy to acquire and can be used to detect the anomaly in database network efficiently.By applying this group of features in Fisher algorithm for anomaly detection,the false positive rate and false negative rate are dramatically reduced.Simultaneously,the model made by using the group of features has the advantages of low algorithm complexity,good detection result and strong generalization ability.Experimental results show that there is higher accuracy when using the features of single-flow and multiflow to construct the anomaly detection model than only using single-flow features.