A dual motion combined by radial and tangential fretting was achieved on a modified hydraulic fretting wear test rig. The dual motion fretting tests of medical pure titanium （TA2） and Ti6Al7Nb alloy in artificial sa...A dual motion combined by radial and tangential fretting was achieved on a modified hydraulic fretting wear test rig. The dual motion fretting tests of medical pure titanium （TA2） and Ti6Al7Nb alloy in artificial saliva were carried out under varied contact inclined angles （45° and 60°）, and the maximum imposed load varied from 200 to 400 N at a constant loading speed of 6 mm/min. The effects of the cyclic vertical force and the inclined angle were investigated in detail. Dynamic analysis in combination with microscopic examinations shows that the wear scar and plastic deformation accumulation present a strong asymmetry. The Ti6Al7Nb has better wear resistance than TA2 in artificial saliva at the same test parameters, and with the increase of inclined angle and decrease of imposed load, the wear reduces accordingly. The wear mechanisms of pure titanium TA2 and Ti6Al7Nb alloy under the condition of dual motion fretting in artificial saliva are abrasive wear, oxidative wear and delamination.展开更多
生物小分子是指生物体内分子量较小的单体物质,植物小分子种类繁多,包括离子、植物激素和代谢物等。了解植物体内这些小分子的动态变化,有助于解析相关的生理功能和调控网络,并为植物细胞学的精确观察创造新的机遇。基于Förster共...生物小分子是指生物体内分子量较小的单体物质,植物小分子种类繁多,包括离子、植物激素和代谢物等。了解植物体内这些小分子的动态变化,有助于解析相关的生理功能和调控网络,并为植物细胞学的精确观察创造新的机遇。基于Förster共振能量转移(Förster resonance energy transfer,FRET)原理设计的基因编码荧光生物传感器/探针,为活体内观察这些小分子的动态变化提供了强有力的工具。通过FRET传感器/探针,能够可视化细胞内特定小分子化合物的浓度,并实时获取高分辨率图像。这一技术因其独特的优势而被广泛应用于植物生理学、发育生物学和环境科学等研究领域。该文总结了近年来植物学研究中使用的FRET传感器/探针,概述了它们的主要设计思路,并阐述了其在检测离子、植物激素及代谢物方面的应用与研究进展,旨在为植物中生物小分子的功能研究提供实用的技术手段和可能的研究方向。展开更多
The continuous mutation and rapid spread of the severe acute respiratory syndrome coronavirus 2(SARSCoV-2)have led to the ineffectiveness of many antiviral drugs targeting the original strain.To keep pace with the vi...The continuous mutation and rapid spread of the severe acute respiratory syndrome coronavirus 2(SARSCoV-2)have led to the ineffectiveness of many antiviral drugs targeting the original strain.To keep pace with the virus’evolutionary speed,there is a crucial need for the development of rapid,cost-effective,and efficient inhibitor screening methods.In this study,we created a novel approach based on fluorescence resonance energy transfer(FRET)technology for in vitro detection of inhibitors targeting the interaction between the SARS-CoV-2 spike protein RBD(s-RBD)and the virus receptor angiotensin-converting enzyme 2(ACE2).Utilizing crystallographic insights into the s-RBD/ACE2 interaction,we modified ACE2 by fusing SNAP tag to its N-terminus(resulting in SA740)and Halo tag to s-RBD’s C-terminus(producing R525H and R541H),thereby ensuring the proximity(<10 nm)of labeled FRET dyes.We found that relative to the R541H fusion protein,R525H exhibited higher FRET efficiency,which attributed to the shortened distance between FRET dyes due to the truncation of s-RBD.Utilizing the sensitive FRET effect between SA740 and R525H,we evaluated its efficacy in detecting inhibitors of SARS-CoV-2 entry in solution and live cells.Ultimately,this FRET-based detection method was demonstrated high sensitivity,rapidity,and simplicity in solution and held promise for high-throughput screening of SARS-CoV-2 inhibitors.展开更多
The effects of nanosecond laser shock peening without coating(LSPwC)and nanosecond stacked femtosecond laser shock peening compound strengthening(LSP-CS)on the surface integrity and fretting fatigue lifetime at 500℃o...The effects of nanosecond laser shock peening without coating(LSPwC)and nanosecond stacked femtosecond laser shock peening compound strengthening(LSP-CS)on the surface integrity and fretting fatigue lifetime at 500℃of GH 4169 dovetail component were investigated.The results show that LSP treatment does not significantly lead to changes in the grain size of GH 4169 alloy,but it introduces a large number of dislocations,resulting in the formation of a plastic deformation layer and residual compressive stress layer.The surface microhardness increased by 20.5%and 28.6%after being treated by LSPwC and LSP-CS,respectively.The surface residual compressive stresses were(-306.5±42.5)MPa and(-404.3±34.7)MPa,respectively;The depth of both the hardening layer and the residual compressive stress layer is 400μm,and along the cross-section with 0-100μm region after LSP-CS treatment has higher hardness and greater residual compressive stress.The fretting fatigue lifetime of the GH 4169 dovetail component at 500℃was increased by 346.8%and 494.9%,which is the result of the combined effects of the hardening layer and the residual stress layer.The LSP-CS treatment can effectively make up for the disadvantage of the LSPwC treatment,and further enhance the fretting fatigue lifetime of the GH 4169 dovetail component at high temperature.展开更多
The evolution of fretting wear behavior of zirconium alloy cladding tubes mated with dimples under the gross slip regime(GSR)was investigated.The findings revealed that the primary wear mechanisms under GSR were delam...The evolution of fretting wear behavior of zirconium alloy cladding tubes mated with dimples under the gross slip regime(GSR)was investigated.The findings revealed that the primary wear mechanisms under GSR were delamination,surface fatigue wear and abrasive wear,and the fretting damage rate mainly depends on delamination.The cross-sectional microstructure of the worn area could be divided into the third-body layer,tribologically transformed structure layer,and general deformation layer,with their formation mechanisms analyzed.Furthermore,the mechanism of wear-induced grain refinement was identified as dynamic recrystallization(DRX),including both continuous DRX and discontinuous DRX.Additionally,the processes of fretting wear and DRX were discussed.展开更多
Submerged Abrasive Waterjet Peening(SAWJP)shows great application potential in augmenting the fatigue properties of metallic parts.Thus,the present work aims to investigate the influence of SAWJP on the Surface Integr...Submerged Abrasive Waterjet Peening(SAWJP)shows great application potential in augmenting the fatigue properties of metallic parts.Thus,the present work aims to investigate the influence of SAWJP on the Surface Integrity(SI)and Fretting Fatigue(FF)properties of Inconel 718(IN718)superalloy and illustrate the microstructural evolution,FF life improvement,and fretting wear mechanism.First,the SI of the IN718 specimen was examined following treatment via SAWJP.Results showed that the specimen subjected to SAWJP formed a total plastic deformation layer of 56μm.The maximum microhardness and Compressive Residual Stress(CRS)measured across the depth of the SAWJP-treated specimens exhibited an increase in values ranging between 522 HV and 541 HV and 1171–1380 MPa,respectively.The FF test results of the specimen before and after SAWJP treatment at ambient temperatures indicated that the FF life of the SAWJP-treated specimen surpassed that of the as-received specimen by a factor of 2.81.The examination of the FF fracture,contact surface,and crack propagation behavior revealed the crucial factors contributing to the enhanced FF resistance of the IN718 specimen,including the gradient nanostructure characterized by ultra-refined grains,substantial CRS,and elevated microhardness,which were all induced by the SAWJP treatment.展开更多
Red fluorescent proteins with large Stokes shift(LSS-RFPs)are advantageous for multicolor imaging applications that allow simultaneous visualizations of multiple biological events.But it is difficult to develop LSS-RF...Red fluorescent proteins with large Stokes shift(LSS-RFPs)are advantageous for multicolor imaging applications that allow simultaneous visualizations of multiple biological events.But it is difficult to develop LSS-RFPs by extending the emission wavelength of RFPs to far-red region.Here,we employed Forster resonance energy transfer(FRET)strategy to engineer the far-red fluorescent proteins with large Stokes shift.LSS-m Apple and LSS-mCherry were constructed by fusing HaloTag to m Apple and mCherry,allowing the fluorophore TMSi R to be connected to these RFPs.FRET between RFPs and TMSi R enabled them to apply the excitation of donor RFPs to emit far-red fluorescence of acceptor TMSi R.The Stokes shifts of LSS-m Apple and LSS-mCherry were 97 nm and 75 nm,respectively.The high FRET efficiency of LSS-mCherry(E_(FRET)=83.7%)can greatly reduce the fluorescence from the donor channel,which did not affect co-imaging with mCherry.In addition,LSS-mCherry also showed excellent photostability(t_(1/2)=449.3 s),enabling stable confocal fluorescence imaging for 15 min under continuous strong excitation.Furthermore,LSS-mCherry was applied for fluorescence labeling and imaging of the nucleus,mitochondria,lysosomes,and endoplasmic reticulum in living cells.Finally,we applied LSS-mCherry to perform multi-color bioimaging of 2–4 channels,and there was no obvious crosstalk between these channels.展开更多
CrN coatings are also employed to protect structural materials in nuclear power plants.It should be noted that the preparation process utilizing physical vapor deposition(PVD)techniques inevitably entails certain defe...CrN coatings are also employed to protect structural materials in nuclear power plants.It should be noted that the preparation process utilizing physical vapor deposition(PVD)techniques inevitably entails certain defects.Such a phenomenon will affect the protective properties of CrN coatings.In this study,low-energy laser shock peening(LE-LSP)with varying energies was employed for the post-treatment of CrN coatings.The effects of different laser energy LE-LSP treatments on the surface morphology,crystal structure and fretting wear properties of CrN coatings were investigated.The results revealed that the surface of the CrN coatings subjected to LE-LSP underwent significant plastic deformation and displayed a regular texture structure.The surface roughness and Vickers hardness of the CrN coatings exhibit a significant increase.Under a laser energy of 150 mJ,the surface hardness exhibits a maximum increase of 2.35 times.The residual stress of CrN coatings diminishes with the augmentation of laser energy due to the formation of surface cracks.Following LE-LSP treatment,the columnar crystal structure of the CrN coating was disrupted and fragmented into fine grains due to the impact force.As the laser energy augments,the fragmented CrN grains undergo further compaction.During fretting wear,all specimens were in the gross slip regime.The wear mechanism of the CrN coating,120 and 150 mJ specimens are primarily dominated by abrasive wear,and accompanied by oxidative wear.For specimens treated with 30,60 and 90 mJ,the predominant wear mechanisms are mainly peeling and abrasive wear,and accompanied by oxidative wear.Both the wear area and wear volume initially increase and then decrease as the laser energy increases.The 150 mJ specimen exhibited the smallest wear area and wear volume of all tested specimens.The wear volume was reduced by 76.32%when compared to that of the CrN coating.This study complements the existing research on PVD/LSP composite strengthening techniques.Introduces a novel post-treatment methodology for PVD coatings.Provides certain theoretical support for subsequent PVD/LSP composite strengthening.展开更多
The discovery of Piezo channels has advanced the understanding of mechanobiology,which acts as mechanosensitive cation channels in sensing mechanical stimuli and regulating various physiological functions.Despite the ...The discovery of Piezo channels has advanced the understanding of mechanobiology,which acts as mechanosensitive cation channels in sensing mechanical stimuli and regulating various physiological functions.Despite the electrophysiological current recording,localized Piezo activation measurement in cells still faces challenges.In this study,we developed a Piezo1-Ca^(2+)biosensor based on Förster Resonance Energy Transfer(FRET)technology by fusing a calcium-sensing module closely to the channel pores,hence to dynamically detect Piezo1 activation.The biosensor expressed in 293T cells showed~120%FRET change to the specific chemical agonist Yoda1,whose response to Piezo1 activation was evaluated with its key-point mutation(L1342G/L1345G).By comparing cytoplasmic and Lyn-tagged membrane calcium biosensors,Piezo1-Ca^(2+)FRET biosensor primarily reflects localized calcium signals near the plasma membrane.Furthermore,by combining Piezo1-Ca^(2+)FRET imaging with varying microfluidic shear conditions,the biosensor exhibited significant yet transient responses to shear stress(~70%FRET change at 2.8 dyn/cm^(2)),with a threshold of effective activation around 1.0 dyn/cm^(2)(i.e.,10μN/cm^(2)).In conclusion,the developed Piezo1-Ca^(2+)FRET biosensor demonstrated Piezo1 activation by chemical agonist and shear force,which provides an imaging tool with improved spatiotemporal resolution for elucidating the mechanosensitivity of Piezo1 channels.The local specificity for Piezo1-Ca^(2+)signal detection by the biosensor requires individual interpretations under different scenarios.展开更多
The torsional fretting wear tests of 7075 aluminum alloy flat against 52100 steel ball in dry condition were carried out on a new high-precision torsional fretting-wear tester.The kinetics behaviors and damage mechani...The torsional fretting wear tests of 7075 aluminum alloy flat against 52100 steel ball in dry condition were carried out on a new high-precision torsional fretting-wear tester.The kinetics behaviors and damage mechanism of 7075 aluminum alloy under different angular displacement amplitudes were investigated in detail.The results show that the torsional fretting running behaviors of 7075 aluminum alloy can be defined by three fretting regimes(i.e.partial slip regime(PSR),mixed fretting regime(MFR) and slip regime(SR)) with the increase of angular displacement amplitudes.In PSR,the damage occurs at the lateral portion of the contact zone with a slight annular shape.However,in MFR and SR,more severe damages are observed and the debris layer covers the wear scars.Friction torque and dissipation energy which are strongly dependent upon the imposed angular displacement amplitudes and presented in three stages were discussed in detail.The mechanisms of torsional fretting wear of aluminum alloy are mainly oxidative wear,abrasive wear and delamination in the three fretting regimes.In addition,the oxidative debris plays an important role during the torsional fretting wear processes.展开更多
Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes rang...Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.展开更多
荧光共振能量转移(Fluorescence Resonance Energy Transfer,FRET)技术被广泛应用于活细胞中生物大分子构象变化和分子间动态相互作用的实时研究.针对光谱串扰和供体受体间的浓度比等困扰FRET效率定量检测的两大难题,已经发展了多种定...荧光共振能量转移(Fluorescence Resonance Energy Transfer,FRET)技术被广泛应用于活细胞中生物大分子构象变化和分子间动态相互作用的实时研究.针对光谱串扰和供体受体间的浓度比等困扰FRET效率定量检测的两大难题,已经发展了多种定量检测FRET效率的方法.作者结合自己的研究结果介绍了多种FRET效率定量检测技术在细胞信号转导机制研究中的应用.展开更多
The fretting wear behavior of 0Cr20Ni32AlTi alloy was investigated with crossed cylinder contact under 80 N at 300 and 400 °C.Wear scar and debris were analyzed systematically by scanning electron microscopy and ...The fretting wear behavior of 0Cr20Ni32AlTi alloy was investigated with crossed cylinder contact under 80 N at 300 and 400 °C.Wear scar and debris were analyzed systematically by scanning electron microscopy and X-ray photoelectron spectroscopy.The results show that the friction logs are mixed fretting regime and gross slip regime with the magnitudes of displacement of 10 and 20 μm,respectively.Severe wear and friction oxidation occur on the material surface.A large number of granular debris produced in the fretting process can be easily congregated and adhered at the contact zone after repeated crushes.The resultant of friction oxidation is mainly composed of Fe3O4,Fe2O3,Cr2O3 and NiO.Temperature and friction are the major factors affecting the oxidation reaction rate.The fretting friction effect can enhance the oxidation reaction activity of surface atoms of 0Cr20Ni32AlTi alloy and reduce the oxidation activation energy.As result,the oxidation reaction rate is accelerated.展开更多
Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and tre...Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and treated titanium, as well as its alloys, against a ZrO2 ball contact were performed on a torsional fretting wear test rig using a simulated physiological medium of serum solution. The treated surfaces were characterized, and the effect of implantation dose on torsional fretting behavior was discussed in detail. The results showed that the torsional fretting running and damage behavior of titanium and its alloys were strongly dependent on the dose of the implanted nitrogen ions and the angular displacement amplitude. The torsional fretting running boundary moved to smaller angular displacement amplitude, and the central light damage zone decreased, as the ion dose increased. The wear mechanisms of titanium and its alloys were oxidative wear, abrasive wear and delamination, with abrasive wear as the most common mechanism of the ion implantation layers.展开更多
基金Project(81170996)supported by the National Natural Science Foundation of China
文摘A dual motion combined by radial and tangential fretting was achieved on a modified hydraulic fretting wear test rig. The dual motion fretting tests of medical pure titanium （TA2） and Ti6Al7Nb alloy in artificial saliva were carried out under varied contact inclined angles （45° and 60°）, and the maximum imposed load varied from 200 to 400 N at a constant loading speed of 6 mm/min. The effects of the cyclic vertical force and the inclined angle were investigated in detail. Dynamic analysis in combination with microscopic examinations shows that the wear scar and plastic deformation accumulation present a strong asymmetry. The Ti6Al7Nb has better wear resistance than TA2 in artificial saliva at the same test parameters, and with the increase of inclined angle and decrease of imposed load, the wear reduces accordingly. The wear mechanisms of pure titanium TA2 and Ti6Al7Nb alloy under the condition of dual motion fretting in artificial saliva are abrasive wear, oxidative wear and delamination.
文摘生物小分子是指生物体内分子量较小的单体物质,植物小分子种类繁多,包括离子、植物激素和代谢物等。了解植物体内这些小分子的动态变化,有助于解析相关的生理功能和调控网络,并为植物细胞学的精确观察创造新的机遇。基于Förster共振能量转移(Förster resonance energy transfer,FRET)原理设计的基因编码荧光生物传感器/探针,为活体内观察这些小分子的动态变化提供了强有力的工具。通过FRET传感器/探针,能够可视化细胞内特定小分子化合物的浓度,并实时获取高分辨率图像。这一技术因其独特的优势而被广泛应用于植物生理学、发育生物学和环境科学等研究领域。该文总结了近年来植物学研究中使用的FRET传感器/探针,概述了它们的主要设计思路,并阐述了其在检测离子、植物激素及代谢物方面的应用与研究进展,旨在为植物中生物小分子的功能研究提供实用的技术手段和可能的研究方向。
基金supported by the National Natural Science Foundation of China(Nos.22225806,22378385,22078314,22278394)Dalian Institute of Chemical Physics(Nos.DICPI202142,DICPI202436,DMU-1&DICP UN202301).
文摘The continuous mutation and rapid spread of the severe acute respiratory syndrome coronavirus 2(SARSCoV-2)have led to the ineffectiveness of many antiviral drugs targeting the original strain.To keep pace with the virus’evolutionary speed,there is a crucial need for the development of rapid,cost-effective,and efficient inhibitor screening methods.In this study,we created a novel approach based on fluorescence resonance energy transfer(FRET)technology for in vitro detection of inhibitors targeting the interaction between the SARS-CoV-2 spike protein RBD(s-RBD)and the virus receptor angiotensin-converting enzyme 2(ACE2).Utilizing crystallographic insights into the s-RBD/ACE2 interaction,we modified ACE2 by fusing SNAP tag to its N-terminus(resulting in SA740)and Halo tag to s-RBD’s C-terminus(producing R525H and R541H),thereby ensuring the proximity(<10 nm)of labeled FRET dyes.We found that relative to the R541H fusion protein,R525H exhibited higher FRET efficiency,which attributed to the shortened distance between FRET dyes due to the truncation of s-RBD.Utilizing the sensitive FRET effect between SA740 and R525H,we evaluated its efficacy in detecting inhibitors of SARS-CoV-2 entry in solution and live cells.Ultimately,this FRET-based detection method was demonstrated high sensitivity,rapidity,and simplicity in solution and held promise for high-throughput screening of SARS-CoV-2 inhibitors.
基金Project(2022YFB3401900)supported by the the National Key R&D of ChinaProject(2025YFHZ0163)supported by the the Science and Technology Projects in Sichuan Province,ChinaProject(2682024GF004)supported by Fundamental Research Funds for the Centeral University,China。
文摘The effects of nanosecond laser shock peening without coating(LSPwC)and nanosecond stacked femtosecond laser shock peening compound strengthening(LSP-CS)on the surface integrity and fretting fatigue lifetime at 500℃of GH 4169 dovetail component were investigated.The results show that LSP treatment does not significantly lead to changes in the grain size of GH 4169 alloy,but it introduces a large number of dislocations,resulting in the formation of a plastic deformation layer and residual compressive stress layer.The surface microhardness increased by 20.5%and 28.6%after being treated by LSPwC and LSP-CS,respectively.The surface residual compressive stresses were(-306.5±42.5)MPa and(-404.3±34.7)MPa,respectively;The depth of both the hardening layer and the residual compressive stress layer is 400μm,and along the cross-section with 0-100μm region after LSP-CS treatment has higher hardness and greater residual compressive stress.The fretting fatigue lifetime of the GH 4169 dovetail component at 500℃was increased by 346.8%and 494.9%,which is the result of the combined effects of the hardening layer and the residual stress layer.The LSP-CS treatment can effectively make up for the disadvantage of the LSPwC treatment,and further enhance the fretting fatigue lifetime of the GH 4169 dovetail component at high temperature.
基金supported by the National Natural Science Foundation of China(No.52105221)the Postdoctoral Fellowship Program(Grade C)of China Postdoctoral Science Foundation(No.GZC20232749)the Youth Innovation Promotion Assessment CAS(No.2022187)and the IMR Innovation Fund(No.2024-PY13).
文摘The evolution of fretting wear behavior of zirconium alloy cladding tubes mated with dimples under the gross slip regime(GSR)was investigated.The findings revealed that the primary wear mechanisms under GSR were delamination,surface fatigue wear and abrasive wear,and the fretting damage rate mainly depends on delamination.The cross-sectional microstructure of the worn area could be divided into the third-body layer,tribologically transformed structure layer,and general deformation layer,with their formation mechanisms analyzed.Furthermore,the mechanism of wear-induced grain refinement was identified as dynamic recrystallization(DRX),including both continuous DRX and discontinuous DRX.Additionally,the processes of fretting wear and DRX were discussed.
基金financially supported by the National Key Research and Development Project,China(Nos.2018YFA0703300,2022YFB4600019)the National Natural Science Foundation of China(Nos.52275148,52405154)+2 种基金the Innovation Program Phase II of AECC Commercial Aircraft Engine Co.Ltd,China(No.HT-3RJC1053-2020)support by the Postdoctoral Fellowship Program of CPSF,China(No.GZB20240219)the Shanghai Sailing Program,China(No.24YF2708100).
文摘Submerged Abrasive Waterjet Peening(SAWJP)shows great application potential in augmenting the fatigue properties of metallic parts.Thus,the present work aims to investigate the influence of SAWJP on the Surface Integrity(SI)and Fretting Fatigue(FF)properties of Inconel 718(IN718)superalloy and illustrate the microstructural evolution,FF life improvement,and fretting wear mechanism.First,the SI of the IN718 specimen was examined following treatment via SAWJP.Results showed that the specimen subjected to SAWJP formed a total plastic deformation layer of 56μm.The maximum microhardness and Compressive Residual Stress(CRS)measured across the depth of the SAWJP-treated specimens exhibited an increase in values ranging between 522 HV and 541 HV and 1171–1380 MPa,respectively.The FF test results of the specimen before and after SAWJP treatment at ambient temperatures indicated that the FF life of the SAWJP-treated specimen surpassed that of the as-received specimen by a factor of 2.81.The examination of the FF fracture,contact surface,and crack propagation behavior revealed the crucial factors contributing to the enhanced FF resistance of the IN718 specimen,including the gradient nanostructure characterized by ultra-refined grains,substantial CRS,and elevated microhardness,which were all induced by the SAWJP treatment.
基金supported by the National Natural Science Foundation of China(Nos.22225806,22078314,22278394,22378385)Dalian Institute of Chemical Physics(Nos.DICPI202142,DICPI202436)。
文摘Red fluorescent proteins with large Stokes shift(LSS-RFPs)are advantageous for multicolor imaging applications that allow simultaneous visualizations of multiple biological events.But it is difficult to develop LSS-RFPs by extending the emission wavelength of RFPs to far-red region.Here,we employed Forster resonance energy transfer(FRET)strategy to engineer the far-red fluorescent proteins with large Stokes shift.LSS-m Apple and LSS-mCherry were constructed by fusing HaloTag to m Apple and mCherry,allowing the fluorophore TMSi R to be connected to these RFPs.FRET between RFPs and TMSi R enabled them to apply the excitation of donor RFPs to emit far-red fluorescence of acceptor TMSi R.The Stokes shifts of LSS-m Apple and LSS-mCherry were 97 nm and 75 nm,respectively.The high FRET efficiency of LSS-mCherry(E_(FRET)=83.7%)can greatly reduce the fluorescence from the donor channel,which did not affect co-imaging with mCherry.In addition,LSS-mCherry also showed excellent photostability(t_(1/2)=449.3 s),enabling stable confocal fluorescence imaging for 15 min under continuous strong excitation.Furthermore,LSS-mCherry was applied for fluorescence labeling and imaging of the nucleus,mitochondria,lysosomes,and endoplasmic reticulum in living cells.Finally,we applied LSS-mCherry to perform multi-color bioimaging of 2–4 channels,and there was no obvious crosstalk between these channels.
基金Supported by National Key R&D Projects(Grant No.2022YFB3401900)Sichuan Provincial Science and Technology Projects(Grant No.2022JDJQ0019)Fundamental Research Funds for the Central University(Grant No.2682024GF004).
文摘CrN coatings are also employed to protect structural materials in nuclear power plants.It should be noted that the preparation process utilizing physical vapor deposition(PVD)techniques inevitably entails certain defects.Such a phenomenon will affect the protective properties of CrN coatings.In this study,low-energy laser shock peening(LE-LSP)with varying energies was employed for the post-treatment of CrN coatings.The effects of different laser energy LE-LSP treatments on the surface morphology,crystal structure and fretting wear properties of CrN coatings were investigated.The results revealed that the surface of the CrN coatings subjected to LE-LSP underwent significant plastic deformation and displayed a regular texture structure.The surface roughness and Vickers hardness of the CrN coatings exhibit a significant increase.Under a laser energy of 150 mJ,the surface hardness exhibits a maximum increase of 2.35 times.The residual stress of CrN coatings diminishes with the augmentation of laser energy due to the formation of surface cracks.Following LE-LSP treatment,the columnar crystal structure of the CrN coating was disrupted and fragmented into fine grains due to the impact force.As the laser energy augments,the fragmented CrN grains undergo further compaction.During fretting wear,all specimens were in the gross slip regime.The wear mechanism of the CrN coating,120 and 150 mJ specimens are primarily dominated by abrasive wear,and accompanied by oxidative wear.For specimens treated with 30,60 and 90 mJ,the predominant wear mechanisms are mainly peeling and abrasive wear,and accompanied by oxidative wear.Both the wear area and wear volume initially increase and then decrease as the laser energy increases.The 150 mJ specimen exhibited the smallest wear area and wear volume of all tested specimens.The wear volume was reduced by 76.32%when compared to that of the CrN coating.This study complements the existing research on PVD/LSP composite strengthening techniques.Introduces a novel post-treatment methodology for PVD coatings.Provides certain theoretical support for subsequent PVD/LSP composite strengthening.
基金funded by National Natural Science Foundation of China(NSFC 12372312)Project of"iangsu Specially-appointed Professor"(MO)National Natural Science Foundation of China(NSFC 12272063)(LD).
文摘The discovery of Piezo channels has advanced the understanding of mechanobiology,which acts as mechanosensitive cation channels in sensing mechanical stimuli and regulating various physiological functions.Despite the electrophysiological current recording,localized Piezo activation measurement in cells still faces challenges.In this study,we developed a Piezo1-Ca^(2+)biosensor based on Förster Resonance Energy Transfer(FRET)technology by fusing a calcium-sensing module closely to the channel pores,hence to dynamically detect Piezo1 activation.The biosensor expressed in 293T cells showed~120%FRET change to the specific chemical agonist Yoda1,whose response to Piezo1 activation was evaluated with its key-point mutation(L1342G/L1345G).By comparing cytoplasmic and Lyn-tagged membrane calcium biosensors,Piezo1-Ca^(2+)FRET biosensor primarily reflects localized calcium signals near the plasma membrane.Furthermore,by combining Piezo1-Ca^(2+)FRET imaging with varying microfluidic shear conditions,the biosensor exhibited significant yet transient responses to shear stress(~70%FRET change at 2.8 dyn/cm^(2)),with a threshold of effective activation around 1.0 dyn/cm^(2)(i.e.,10μN/cm^(2)).In conclusion,the developed Piezo1-Ca^(2+)FRET biosensor demonstrated Piezo1 activation by chemical agonist and shear force,which provides an imaging tool with improved spatiotemporal resolution for elucidating the mechanosensitivity of Piezo1 channels.The local specificity for Piezo1-Ca^(2+)signal detection by the biosensor requires individual interpretations under different scenarios.
基金Project(2007CB714704) supported by the National Basic Research Program of ChinaProjects(50775192,50821063) supported by the National Natural Science Foundation of China
文摘The torsional fretting wear tests of 7075 aluminum alloy flat against 52100 steel ball in dry condition were carried out on a new high-precision torsional fretting-wear tester.The kinetics behaviors and damage mechanism of 7075 aluminum alloy under different angular displacement amplitudes were investigated in detail.The results show that the torsional fretting running behaviors of 7075 aluminum alloy can be defined by three fretting regimes(i.e.partial slip regime(PSR),mixed fretting regime(MFR) and slip regime(SR)) with the increase of angular displacement amplitudes.In PSR,the damage occurs at the lateral portion of the contact zone with a slight annular shape.However,in MFR and SR,more severe damages are observed and the debris layer covers the wear scars.Friction torque and dissipation energy which are strongly dependent upon the imposed angular displacement amplitudes and presented in three stages were discussed in detail.The mechanisms of torsional fretting wear of aluminum alloy are mainly oxidative wear,abrasive wear and delamination in the three fretting regimes.In addition,the oxidative debris plays an important role during the torsional fretting wear processes.
基金supported by the National Natural Science Foundation of China (No 50875252)the Program for New Century Excellent Talents in Universities (NoNCET-06-0479)the Natural Science Foundation of Jiangsu Province (NoBK2008005)
文摘Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.
文摘荧光共振能量转移(Fluorescence Resonance Energy Transfer,FRET)技术被广泛应用于活细胞中生物大分子构象变化和分子间动态相互作用的实时研究.针对光谱串扰和供体受体间的浓度比等困扰FRET效率定量检测的两大难题,已经发展了多种定量检测FRET效率的方法.作者结合自己的研究结果介绍了多种FRET效率定量检测技术在细胞信号转导机制研究中的应用.
基金Project (51075342) supported by the National Natural Science Foundation of ChinaProject (2007CB714704) supported by the National Basic Research Program of China
文摘The fretting wear behavior of 0Cr20Ni32AlTi alloy was investigated with crossed cylinder contact under 80 N at 300 and 400 °C.Wear scar and debris were analyzed systematically by scanning electron microscopy and X-ray photoelectron spectroscopy.The results show that the friction logs are mixed fretting regime and gross slip regime with the magnitudes of displacement of 10 and 20 μm,respectively.Severe wear and friction oxidation occur on the material surface.A large number of granular debris produced in the fretting process can be easily congregated and adhered at the contact zone after repeated crushes.The resultant of friction oxidation is mainly composed of Fe3O4,Fe2O3,Cr2O3 and NiO.Temperature and friction are the major factors affecting the oxidation reaction rate.The fretting friction effect can enhance the oxidation reaction activity of surface atoms of 0Cr20Ni32AlTi alloy and reduce the oxidation activation energy.As result,the oxidation reaction rate is accelerated.
基金Projects(U1530136,51375407)supported by the National Natural Science Foundation of China
文摘Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and treated titanium, as well as its alloys, against a ZrO2 ball contact were performed on a torsional fretting wear test rig using a simulated physiological medium of serum solution. The treated surfaces were characterized, and the effect of implantation dose on torsional fretting behavior was discussed in detail. The results showed that the torsional fretting running and damage behavior of titanium and its alloys were strongly dependent on the dose of the implanted nitrogen ions and the angular displacement amplitude. The torsional fretting running boundary moved to smaller angular displacement amplitude, and the central light damage zone decreased, as the ion dose increased. The wear mechanisms of titanium and its alloys were oxidative wear, abrasive wear and delamination, with abrasive wear as the most common mechanism of the ion implantation layers.
文摘铁是生命必需的微量元素,ferroportin(Fpn)是小肠吸收细胞铁释放的重要蛋白。新近发现肝脏分泌的抗菌多肽hepcidin具有调节肠铁吸收的重要作用,但目前尚缺少Fpn和hepcidin发生作用的实验依据。应用荧光共振能量转移技术(fluorescence resonance energy transfer,FRET)对hepcidin和Fpn之间的作用关系进行了深入研究。首先进行了hepcidin-CF P融合蛋白表达载体的构建及表达鉴定;然后对含YFP,Fpn-YFP基因动物细胞表达载体的构建、表达和FRET检测。实验结果证实hepcidin和Fpn之间存在直接的相互作用,并发现两种蛋白发生相互作用后hepcidin也在细胞质中有分布。为临床治疗铁代谢紊乱性疾病提供了新的治疗策略和重要理论依据。
