目的探讨棕榈酰化修饰调节非受体酪氨酸激酶Fyn活性的分子机制。方法利用荧光共振能量转移(fluorescence resonance energy transfer,FRET)技术实时检测细胞中的Fyn活性,并结合棕榈酰化位点缺失和共转染蛋白质酪氨酸激酶(C-terminal Src...目的探讨棕榈酰化修饰调节非受体酪氨酸激酶Fyn活性的分子机制。方法利用荧光共振能量转移(fluorescence resonance energy transfer,FRET)技术实时检测细胞中的Fyn活性,并结合棕榈酰化位点缺失和共转染蛋白质酪氨酸激酶(C-terminal Src kinase,CSK)表达质粒研究其分子机制。结果实验发现,(C3,C6)任一位点的棕榈酰化缺失能引起Fyn的高活性表达,且C6位点影响更显著。已知CSK激活后发生膜转移,FRET检测证实其对细胞中的Fyn活性有下调作用,但不能有效调控(C3,C6)棕榈酰化位点缺失的Fyn(GSS)活性。结论本文结果初步支持了Fyn活性受细胞内的物理空间定位分布的一种调控机制假设,即棕榈酰化缺失的Fyn(GSS)受细胞膜上CSK抑制性的调节作用被减弱,从而促进了组成性的高活性表达。展开更多
In pressurized water reactor(PWR),fretting wear is one of the main causes of fuel assembly failure.Moreover,the operation condition of cladding is complex and harsh.A unique fretting damage test equipment was develope...In pressurized water reactor(PWR),fretting wear is one of the main causes of fuel assembly failure.Moreover,the operation condition of cladding is complex and harsh.A unique fretting damage test equipment was developed and tested to simulate the fretting damage evolution process of cladding in the PWR environment.It can simulate the fretting wear experiment of PWR under different temperatures(maximum temperature is 350℃),displacement amplitude,vibration frequency,and normal force.The fretting wear behavior of Zr-4 alloy under different temperature environments was tested.In addition,the evolution of wear scar morphology,profile,and wear volume was studied using an optical microscope(OM),scanning electron microscopy(SEM),and a 3D white light interferometer.Results show that higher water temperature evidently decreased the cladding wear volume,the wear mechanism of Zr-4 cladding changed from abrasive wear to adhesive wear and the formation of an oxide layer on the wear scar reduced the wear volume and maximum wear depth.展开更多
In this paper,a numerical model of fretting fatigue analysis of cablewire and the fretting fatigue damage constitutive model considering the multi-axis effect were established,and the user material subroutine UMAT was...In this paper,a numerical model of fretting fatigue analysis of cablewire and the fretting fatigue damage constitutive model considering the multi-axis effect were established,and the user material subroutine UMAT was written.Then,the constitutive model of wear morphology evolution of cable wire and the constitutive model of pitting evolution considering the mechanical-electrochemical effect were established,respectively.The corresponding subroutines UMESHMOTION_Wear and UMESHMOTION_Wear_Corrosion were written,and the fretting fatigue lifewas further predicted.The results showthat the numerical simulation life obtained by the programin this paper has the same trend as the tested one;the error is only about 0.7%in the medium life area;When the normal contact force increases from 120 to 240 N,the fretting life of cable wire decreases by 25%;When the evolution of wear morphology and corrosion effect are considered simultaneously,the depth of the wear zone exceeds 0.08mm after 600,000 loads,which ismuch larger than 0.04 mmwhen only the evolution of wear morphology is considered.When the evolution of wear morphology and corrosion morphology is considered simultaneously,the damage covers the whole contact surface after 300,000 loads,and the penetrating damage zone forms after 450,000 loads,which is obviously faster than that when only the wearmorphology evolution is considered.Themethod proposed in this paper can provide a feasible numerical simulation scheme for the visualization of the damage process and accurate life prediction of cable-supported bridges.展开更多
目的探索Jurkat T细胞中胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)活性动力学以及基质刚度对ERK活性的影响。方法利用荧光共振能量转移(fluorescence resonance energy transfer,FRET)技术实时观测Jurkat细胞中ER...目的探索Jurkat T细胞中胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)活性动力学以及基质刚度对ERK活性的影响。方法利用荧光共振能量转移(fluorescence resonance energy transfer,FRET)技术实时观测Jurkat细胞中ERK活性的变化,或细胞处于I型胶原基质胶中检测其影响。结果部分Jurkat细胞中存在ERK活性脉冲现象,频率约为3次/h,FRET振幅变化约为20%。在抗体激活T细胞抗原受体(T-cell receptor,TCR)的条件下,ERK脉冲依然存在,频率和振幅无显著变化。当细胞处于I型胶原水凝胶中,随着胶基质刚度增加,脉冲频率有所下调。结论Jurkat T细胞中存在自发的ERK活性脉冲现象,初步实验显示其频率受基质刚度影响。而该信号波动的生理意义和分子机制仍有待探索。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 introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component （such as carbon, nitrogen, sulphur and oxygen, ...The introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component （such as carbon, nitrogen, sulphur and oxygen, etc） thermo-chemical treatment（LTGMTT） can overcome the brittleness of nitriding process, and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly. However, there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now, which limits the applications of fretting. So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50 （0.48%C） steel prepared by low temperature gas multi-component thermo-chemical treatment （LTGMTT） technology. The fretting wear tests of the modified layer flat specimens and its substrate （LZ50 steel） against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2 μm to 40 μm. Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope（SEM）, optical microscope（OM）, X-ray diffraction（XRD） and surface profilometer. The experimental results showed that the modified layer with a total thickness of 60 μm was consisted of three parts, i.e., loose layer, compound layer and diffusion layer. Compared with the substrate, the range of the mixed fretting regime（MFR） of the LTGMTT modified layer diminished, and the slip regime（SR） of the modified layer shifted to the direction of smaller displacement amplitude. The coefficient of friction（COF） of the modified layer was lower than that of the substrate in the initial stage. For the modified layer, the damage in partial slip regime（PSR） was very slight. The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination. The modified layer presented better wear resistance than the substrate in PSR and MFR; however, in SR, the wear resistance of the modified layer decreased with the increase of the displacement amplitudes. The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.展开更多
This study investigated the fretting wear and fatigue of full-scale railway axles.Fatigue tests were conducted on full-scale railway axles,and the fretting wear and fretting fatigue in the fretted zone of the railway ...This study investigated the fretting wear and fatigue of full-scale railway axles.Fatigue tests were conducted on full-scale railway axles,and the fretting wear and fretting fatigue in the fretted zone of the railway axles were analysed.Three-dimensional finite element models were established based on the experimental results.Then,multi-axial fatigue parameters and a linear elastic fracture mechanics-based approach were used to investigate the fretting fatigue crack initiation and propagation,respectively,in which the role of the fretting wear was taken into account.The experimental and simulated results showed that the fretted zone could be divided into zones I-III according to the surface damage morphologies.Fretting wear alleviated the stress concentration near the wheel seat edge and resulted in a new stress concentration near the worn/unworn boundary in zone II,which greatly promoted the fretting crack initiation at the inner side of the fretted zone.Meanwhile,the stress concentration also increased the equivalent stress intensity factor range DKeq below the mating surface,and thus promoted the propagation of fretting fatigue crack.Based on these findings,the effect of the stress redistribution resulting from fretting wear is suggested to be taken into account when evaluating the fretting fatigue in railway axles.展开更多
基金Supported by National Key R&D Program of China(Grant No.2022YFB3401901)Key Program of National Natural Science Foundation of China(Grant No.U2067221)+2 种基金Sichuan Provincial Science and Technology Planning Project(Grant Nos.2022JDJQ0019 and 2022ZYD0029)Funds for China Postdoctoral Science Foundation(Grant No.2022M713008)Sichuan Provincial Innovative Talent Funding Project for Postdoctoral Fellows(Grant No.BX202225).
文摘In pressurized water reactor(PWR),fretting wear is one of the main causes of fuel assembly failure.Moreover,the operation condition of cladding is complex and harsh.A unique fretting damage test equipment was developed and tested to simulate the fretting damage evolution process of cladding in the PWR environment.It can simulate the fretting wear experiment of PWR under different temperatures(maximum temperature is 350℃),displacement amplitude,vibration frequency,and normal force.The fretting wear behavior of Zr-4 alloy under different temperature environments was tested.In addition,the evolution of wear scar morphology,profile,and wear volume was studied using an optical microscope(OM),scanning electron microscopy(SEM),and a 3D white light interferometer.Results show that higher water temperature evidently decreased the cladding wear volume,the wear mechanism of Zr-4 cladding changed from abrasive wear to adhesive wear and the formation of an oxide layer on the wear scar reduced the wear volume and maximum wear depth.
基金supported by the grant from National Key Research and Development Program of China (Grant No.2021YFF0602005)National Natural Science Foundation of China (No.51678135),which are gratefully acknowledged.
文摘In this paper,a numerical model of fretting fatigue analysis of cablewire and the fretting fatigue damage constitutive model considering the multi-axis effect were established,and the user material subroutine UMAT was written.Then,the constitutive model of wear morphology evolution of cable wire and the constitutive model of pitting evolution considering the mechanical-electrochemical effect were established,respectively.The corresponding subroutines UMESHMOTION_Wear and UMESHMOTION_Wear_Corrosion were written,and the fretting fatigue lifewas further predicted.The results showthat the numerical simulation life obtained by the programin this paper has the same trend as the tested one;the error is only about 0.7%in the medium life area;When the normal contact force increases from 120 to 240 N,the fretting life of cable wire decreases by 25%;When the evolution of wear morphology and corrosion effect are considered simultaneously,the depth of the wear zone exceeds 0.08mm after 600,000 loads,which ismuch larger than 0.04 mmwhen only the evolution of wear morphology is considered.When the evolution of wear morphology and corrosion morphology is considered simultaneously,the damage covers the whole contact surface after 300,000 loads,and the penetrating damage zone forms after 450,000 loads,which is obviously faster than that when only the wearmorphology evolution is considered.Themethod proposed in this paper can provide a feasible numerical simulation scheme for the visualization of the damage process and accurate life prediction of cable-supported bridges.
文摘目的探索Jurkat T细胞中胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)活性动力学以及基质刚度对ERK活性的影响。方法利用荧光共振能量转移(fluorescence resonance energy transfer,FRET)技术实时观测Jurkat细胞中ERK活性的变化,或细胞处于I型胶原基质胶中检测其影响。结果部分Jurkat细胞中存在ERK活性脉冲现象,频率约为3次/h,FRET振幅变化约为20%。在抗体激活T细胞抗原受体(T-cell receptor,TCR)的条件下,ERK脉冲依然存在,频率和振幅无显著变化。当细胞处于I型胶原水凝胶中,随着胶基质刚度增加,脉冲频率有所下调。结论Jurkat T细胞中存在自发的ERK活性脉冲现象,初步实验显示其频率受基质刚度影响。而该信号波动的生理意义和分子机制仍有待探索。
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supported by National Natural Science Foundation of China (Grant No. 50521503)National Basic Research Program of China (973 Program, Grant No. 2007CB714704)National Hi-tech Research and Development Program of China (863 Program, Grant No. 2006AA04Z406)
文摘The introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component （such as carbon, nitrogen, sulphur and oxygen, etc） thermo-chemical treatment（LTGMTT） can overcome the brittleness of nitriding process, and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly. However, there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now, which limits the applications of fretting. So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50 （0.48%C） steel prepared by low temperature gas multi-component thermo-chemical treatment （LTGMTT） technology. The fretting wear tests of the modified layer flat specimens and its substrate （LZ50 steel） against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2 μm to 40 μm. Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope（SEM）, optical microscope（OM）, X-ray diffraction（XRD） and surface profilometer. The experimental results showed that the modified layer with a total thickness of 60 μm was consisted of three parts, i.e., loose layer, compound layer and diffusion layer. Compared with the substrate, the range of the mixed fretting regime（MFR） of the LTGMTT modified layer diminished, and the slip regime（SR） of the modified layer shifted to the direction of smaller displacement amplitude. The coefficient of friction（COF） of the modified layer was lower than that of the substrate in the initial stage. For the modified layer, the damage in partial slip regime（PSR） was very slight. The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination. The modified layer presented better wear resistance than the substrate in PSR and MFR; however, in SR, the wear resistance of the modified layer decreased with the increase of the displacement amplitudes. The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.
基金the Independent Research Project of the State Key Laboratory of Traction Power(No.2018TPL_Z01)the National Natural Science Foundation of China(No.51375406)the Fundamental Research Funds for the Central Universities(No.2682018CX68).
文摘This study investigated the fretting wear and fatigue of full-scale railway axles.Fatigue tests were conducted on full-scale railway axles,and the fretting wear and fretting fatigue in the fretted zone of the railway axles were analysed.Three-dimensional finite element models were established based on the experimental results.Then,multi-axial fatigue parameters and a linear elastic fracture mechanics-based approach were used to investigate the fretting fatigue crack initiation and propagation,respectively,in which the role of the fretting wear was taken into account.The experimental and simulated results showed that the fretted zone could be divided into zones I-III according to the surface damage morphologies.Fretting wear alleviated the stress concentration near the wheel seat edge and resulted in a new stress concentration near the worn/unworn boundary in zone II,which greatly promoted the fretting crack initiation at the inner side of the fretted zone.Meanwhile,the stress concentration also increased the equivalent stress intensity factor range DKeq below the mating surface,and thus promoted the propagation of fretting fatigue crack.Based on these findings,the effect of the stress redistribution resulting from fretting wear is suggested to be taken into account when evaluating the fretting fatigue in railway axles.
