Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulatio...Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals;and the grinding force,coefficient of friction,stress distribution,plastic damage behaviors,and abrasive damage were systematically investigated.The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction.The grinding force,grinding induced stress,subsurface damage depth,and abrasive wear increase as the transverse interacted distance increases.However,there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length.Appropriate interacted distances between abrasives can decrease grinding force,coefficient of friction,grinding induced stress,subsurface damage depth,and abrasive wear during the grinding process.The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results,i.e.amorphous atoms,high-pressure phase transition,dislocations,stacking faults,and lattice distortions.The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.展开更多
To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF_(2) single crystals,nanoscratch tests of MgF_(2) single crystals with different crystal planes a...To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF_(2) single crystals,nanoscratch tests of MgF_(2) single crystals with different crystal planes and directions were systematically performed,and surface morphologies of the scratched grooves under different conditions were analyzed.The experimental results indicated that anisotropy considerably affected the damage evolution in the machining process of MgF_(2) single crystals.A stress field model induced by the scratch was developed by considering the anisotropy,which indicated that during the loading process,median cracks induced by the tensile stress initiated and propagated at the front of the indenter.Lateral cracks induced by tensile stress initiated and propagated on the subsurface during the unloading process.In addition,surface radial cracks induced by the tensile stress were easily generated during the unloading process.The stress change led to the deflection of the propagation direction of lateral cracks.Therefore,the lateral cracks propagated to the workpiece surface,resulting in brittle removal in the form of chunk chips.The plastic deformation parameter indicated that the more the slip systems were activated,the more easily the plastic deformation occurred.The cleavage fracture parameter indicated that the cracks propagated along the activated cleavage planes,and the brittle chunk removal was owing to the subsurface cleavage cracks propagating to the crystal surface.Under the same processing parameters,the scratch of the(001)crystal plane along the[100]crystal-orientation was found to be the most conducive to achieving plastic machining of MgF_(2) single crystals.The theoretical results agreed well with the experimental results,which will not only enhance the understanding of the anisotropy dependence of the damage evolution and removal process during the machining of MgF_(2) crystals,but also provide a theoretical foundation for achieving the high-efficiency and low-damage processing of anisotropic single crystals.展开更多
A systems biology approach was employed to gain insight into tick biology and interactions between vectors and pathogens.Haemaphysalis longicornis serves as one of the primary vectors of Babesia microti,significantly ...A systems biology approach was employed to gain insight into tick biology and interactions between vectors and pathogens.Haemaphysalis longicornis serves as one of the primary vectors of Babesia microti,significantly impacting human and animal health.Obtaining more information about their relationship is crucial for a comprehensive un-derstanding of tick and pathogen biology,pathogen transmission dynamics,and potential control strategies.RNA sequencing of uninfected and B.microti-infected ticks resulted in the identification of 15056 unigenes.Among these,1051 were found to be differentially expressed,with 796 being upregulated and 255 downregulated(P<0.05).Integrated tran-scriptomics datasets revealed the pivotal role of immune-related pathways,including the Toll,Janus kinase/signal transducer and activator of transcription(JAK-STAT),immunod-eficiency,and RNA interference(RNAi)pathways,in response to infection.Consequently,3 genes encoding critical transcriptional factor Dorsal,Relish,and STAT were selected for RNAi experiments.The knockdown of Dorsal,Relish,and STAT resulted in a substantial increase in Babesia infection levels compared to the respective controls.These findings significantly advanced our understanding of tick–Babesia molecular interactions and pro-posed novel tick antigens as potential vaccine targets against tick infestations and pathogen transmission.展开更多
Metal halide perovskites have become one of the most competitive new-generation optoelectronic materials due to their excellent optoelectronic properties. Vacuum evaporation can produce high-purity and large-area film...Metal halide perovskites have become one of the most competitive new-generation optoelectronic materials due to their excellent optoelectronic properties. Vacuum evaporation can produce high-purity and large-area films, leading to the wide application of this method in the semiconductor industry and optoelectronics field. However, the electroluminescent performance of vacuum-evaporated perovskite light-emitting diodes(PeLEDs) still lags behind those counterparts fabricated by solution methods. Herein, based on vacuum evaporation, 3D perovskite films are obtained by three-source co-evaporation.Considering the unique quantum well structure of quasi-2D perovskite can significantly enhance the exciton binding energy and improve the radiative recombination rate, leading to a high photoluminescence quantum yield(PLQY). Subsequently,the highly stable and low-defect-density quasi-2D perovskite is introduced into 3D perovskite films through post-treatment with phenethylammonium chloride(PEACl). To minimize the degradation of film quality caused by PEACl treatment, a layer of guanidinium bromide(GABr) is vacuum evaporated on top of PEACl treatment to further improve the quality of emitting layer. Finally, under the synergistic post-processing modification of PEACl and GABr, blue PeLEDs with a maximum external quantum efficiency(EQE) of 6.09% and a maximum brightness of 1325 cd/m^(2) are successfully obtained. This work deepens the understanding of 2D/3D heterojunctions and provides a new approach to construct PeLEDs with high performance.展开更多
Ultra-precision parallel grinding is widely used in the machining of complex optic components with high tolerance and excellent surface finish.However,the micro-waviness raised from the relative motion error of the gr...Ultra-precision parallel grinding is widely used in the machining of complex optic components with high tolerance and excellent surface finish.However,the micro-waviness raised from the relative motion error of the grinding tool is frequently involved in the grinding process despite the fine dressing and dynamic balance work carried out,which posed a remarkable impact on the surface quality and form accuracy.Therefore,it is essential to investigate the evolution mechanism of the micro-waviness error and determine a relevant strategy to suppress this kind of error.In this paper,a model of the distribution of grinding points corresponding to the relative motion error of the grinding wheel is developed by considering the phase effect.A close relationship is found between the micro-waviness geometry and the distribution of grinding points.This indicates that the phase shift is a significant parameter to determine the waviness pattern,and the uniform distribution of grinding points is beneficial to suppress the micro-waviness in parallel grinding.Finally,an error-suppression strategy is proposed by adjusting the wheel speed to maintain an appropriate phase shift to suppress the micro-waviness error.This work provides a new method to control the micro-waviness and reduce the effect of the waviness error on the surface generation.展开更多
基金supported by the National Natural Science Foundation of China(52375420,52005134 and51675453)Natural Science Foundation of Heilongjiang Province of China(YQ2023E014)+5 种基金Self-Planned Task(No.SKLRS202214B)of State Key Laboratory of Robotics and System(HIT)China Postdoctoral Science Foundation(2022T150163)Young Elite Scientists Sponsorship Program by CAST(No.YESS20220463)State Key Laboratory of Robotics and System(HIT)(SKLRS-2022-ZM-14)Open Fund of Key Laboratory of Microsystems and Microstructures Manufacturing(HIT)(2022KM004)Fundamental Research Funds for the Central Universities(Grant Nos.HIT.OCEF.2022024 and FRFCU5710051122)。
文摘Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals;and the grinding force,coefficient of friction,stress distribution,plastic damage behaviors,and abrasive damage were systematically investigated.The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction.The grinding force,grinding induced stress,subsurface damage depth,and abrasive wear increase as the transverse interacted distance increases.However,there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length.Appropriate interacted distances between abrasives can decrease grinding force,coefficient of friction,grinding induced stress,subsurface damage depth,and abrasive wear during the grinding process.The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results,i.e.amorphous atoms,high-pressure phase transition,dislocations,stacking faults,and lattice distortions.The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.
基金supported by the National Natural Science Foundation of China (52005134&51975154)China Postdoctoral Science Foundation (2022T150163, 2020M670901)+4 种基金Self-Planned Task (No. SKLRS202214B) of State Key Laboratory of Robotics and System (HIT)Heilongjiang Postdoctoral Fund (LBH-Z20016)Shenzhen Science and Technology Program (GJHZ20210705142804012)Fundamental Research Funds for the Central Universities(FRFCU5710051122)Open Fund of ZJUT Xinchang Research Institute
文摘To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF_(2) single crystals,nanoscratch tests of MgF_(2) single crystals with different crystal planes and directions were systematically performed,and surface morphologies of the scratched grooves under different conditions were analyzed.The experimental results indicated that anisotropy considerably affected the damage evolution in the machining process of MgF_(2) single crystals.A stress field model induced by the scratch was developed by considering the anisotropy,which indicated that during the loading process,median cracks induced by the tensile stress initiated and propagated at the front of the indenter.Lateral cracks induced by tensile stress initiated and propagated on the subsurface during the unloading process.In addition,surface radial cracks induced by the tensile stress were easily generated during the unloading process.The stress change led to the deflection of the propagation direction of lateral cracks.Therefore,the lateral cracks propagated to the workpiece surface,resulting in brittle removal in the form of chunk chips.The plastic deformation parameter indicated that the more the slip systems were activated,the more easily the plastic deformation occurred.The cleavage fracture parameter indicated that the cracks propagated along the activated cleavage planes,and the brittle chunk removal was owing to the subsurface cleavage cracks propagating to the crystal surface.Under the same processing parameters,the scratch of the(001)crystal plane along the[100]crystal-orientation was found to be the most conducive to achieving plastic machining of MgF_(2) single crystals.The theoretical results agreed well with the experimental results,which will not only enhance the understanding of the anisotropy dependence of the damage evolution and removal process during the machining of MgF_(2) crystals,but also provide a theoretical foundation for achieving the high-efficiency and low-damage processing of anisotropic single crystals.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,National Natural Science Foundation of China(32170142,81971917,81271792,81471571)Jiangsu Natural Science Foundation(BK20211310),and funding from Suzhou International Joint Laboratory for Diagnosis and Treatment of Brain Diseases.
文摘A systems biology approach was employed to gain insight into tick biology and interactions between vectors and pathogens.Haemaphysalis longicornis serves as one of the primary vectors of Babesia microti,significantly impacting human and animal health.Obtaining more information about their relationship is crucial for a comprehensive un-derstanding of tick and pathogen biology,pathogen transmission dynamics,and potential control strategies.RNA sequencing of uninfected and B.microti-infected ticks resulted in the identification of 15056 unigenes.Among these,1051 were found to be differentially expressed,with 796 being upregulated and 255 downregulated(P<0.05).Integrated tran-scriptomics datasets revealed the pivotal role of immune-related pathways,including the Toll,Janus kinase/signal transducer and activator of transcription(JAK-STAT),immunod-eficiency,and RNA interference(RNAi)pathways,in response to infection.Consequently,3 genes encoding critical transcriptional factor Dorsal,Relish,and STAT were selected for RNAi experiments.The knockdown of Dorsal,Relish,and STAT resulted in a substantial increase in Babesia infection levels compared to the respective controls.These findings significantly advanced our understanding of tick–Babesia molecular interactions and pro-posed novel tick antigens as potential vaccine targets against tick infestations and pathogen transmission.
基金supported by the National Key Research and Development Program of China(No.2022YFA1204800)the National Natural Science Foundation of China(Grant No.U2001219)+1 种基金Hubei Provincial Natural Science Foundation of China(No.2023AFA034)the Key R&D program of Hubei Province(No.2023BAB102).
文摘Metal halide perovskites have become one of the most competitive new-generation optoelectronic materials due to their excellent optoelectronic properties. Vacuum evaporation can produce high-purity and large-area films, leading to the wide application of this method in the semiconductor industry and optoelectronics field. However, the electroluminescent performance of vacuum-evaporated perovskite light-emitting diodes(PeLEDs) still lags behind those counterparts fabricated by solution methods. Herein, based on vacuum evaporation, 3D perovskite films are obtained by three-source co-evaporation.Considering the unique quantum well structure of quasi-2D perovskite can significantly enhance the exciton binding energy and improve the radiative recombination rate, leading to a high photoluminescence quantum yield(PLQY). Subsequently,the highly stable and low-defect-density quasi-2D perovskite is introduced into 3D perovskite films through post-treatment with phenethylammonium chloride(PEACl). To minimize the degradation of film quality caused by PEACl treatment, a layer of guanidinium bromide(GABr) is vacuum evaporated on top of PEACl treatment to further improve the quality of emitting layer. Finally, under the synergistic post-processing modification of PEACl and GABr, blue PeLEDs with a maximum external quantum efficiency(EQE) of 6.09% and a maximum brightness of 1325 cd/m^(2) are successfully obtained. This work deepens the understanding of 2D/3D heterojunctions and provides a new approach to construct PeLEDs with high performance.
基金The National Natural Science Foundation of China(52105481)China Postdoctoral Science Foundation(2019M663681)+4 种基金National Science Fund for Excellent Young Scholars(51722509)National Key Research and Development Program of China(2017YFB1104700)Program for Science and Technology Innovation Group of Shaanxi Province(2019TD-011)Key Research and Development Program of Shaanxi Province(2020ZDLGY04-02)Natural Science Foundation of Zhejiang Province(LQ21E050010).
文摘Ultra-precision parallel grinding is widely used in the machining of complex optic components with high tolerance and excellent surface finish.However,the micro-waviness raised from the relative motion error of the grinding tool is frequently involved in the grinding process despite the fine dressing and dynamic balance work carried out,which posed a remarkable impact on the surface quality and form accuracy.Therefore,it is essential to investigate the evolution mechanism of the micro-waviness error and determine a relevant strategy to suppress this kind of error.In this paper,a model of the distribution of grinding points corresponding to the relative motion error of the grinding wheel is developed by considering the phase effect.A close relationship is found between the micro-waviness geometry and the distribution of grinding points.This indicates that the phase shift is a significant parameter to determine the waviness pattern,and the uniform distribution of grinding points is beneficial to suppress the micro-waviness in parallel grinding.Finally,an error-suppression strategy is proposed by adjusting the wheel speed to maintain an appropriate phase shift to suppress the micro-waviness error.This work provides a new method to control the micro-waviness and reduce the effect of the waviness error on the surface generation.
