The microstructure evolution of secondary austenite in 2507 duplex stainless steel was investigated by means of optical metallography,scanning electron microscopy and confocal scanning laser microscopy.Four types of s...The microstructure evolution of secondary austenite in 2507 duplex stainless steel was investigated by means of optical metallography,scanning electron microscopy and confocal scanning laser microscopy.Four types of secondary austenite(γ2)morphologies including partially transformed austenite,grain boundary austenite,Widmannstätten austenite(WA)and intragranular austenite could be formed during cooling after solution treatment.It was concluded that secondary austenite morphology was mainly dependent on cooling rates.Two mechanisms of WA formation were proposed.WA nucleated at grain boundary of ferrite or at the formed phase boundary.Transmission electron microscopy(TEM)analysis displayed that WA grew in parallel to the ferrite.The effects of Cr_(2)N on secondary austenite precipitation were discussed in detail.Once Cr_(2)N was involved,a mechanism was proposed that secondary austenite formed by element diffusion,leading to the migration of the austenite–ferrite interface.Cr_(2)N acted as the nucleation sites forγ2 and provided the nitrogen for the transformation;meanwhile,the precipitation of Cr_(2)N during the rapid cooling was captured by TEM.A process of nucleation followed by diffusion was concluded to be the formation of secondary austenite with no Cr_(2)N precipitated.The decomposition of secondary austenite was also studied,which was found to be a diffusion mechanism followed by displacement in connection with the element distribution.展开更多
Background: Ischemic stroke accounts for approximately 80% of all cases of stroke and has the highest rates of morbidity,disability,mortality,and recurrence. The neutrophil-to-lymphocyte ratio (NLR) is a novel,feasibl...Background: Ischemic stroke accounts for approximately 80% of all cases of stroke and has the highest rates of morbidity,disability,mortality,and recurrence. The neutrophil-to-lymphocyte ratio (NLR) is a novel,feasible marker representing an integrated response to inflammation. The purpose of the current review is to evaluate all available evidence from clinical observational trials about the relationships between NLR and ischemic stroke. Methods: We searched PubMed,Embase,and CNKI for clinical observational trials on NLR published up to August 1,2018,and made a brief summary about the predictive value of the correlation between NLR and ischemic stroke. Results: A high NLR is associated with increased risk of developing stroke and is a new addition to the traditional risk factors of atrial fibrillation and carotid artery stenosis. NLR on admission is an independent predictor of short- and long-term mortality in patients with acute ischemic stroke. In patients receiving recombinant tissue plasminogen activator or endovascular treatments,high NLR was reported with higher mortality or major disability. Conclusion: NLR provides an easy,useful method to predict the incidence,severity,and prognosis of ischemic stroke;thus,it can emerge as a new potential target for anti-inflammatory treatment and development of therapeutic strategies.展开更多
基金This work was supported by the National Key Research and Development Program of China(No.2016YFB0300201)has received funding from the Key Research and Innovation Program in Zhejiang Province,China(Grant agreement No.2020C01007).
文摘The microstructure evolution of secondary austenite in 2507 duplex stainless steel was investigated by means of optical metallography,scanning electron microscopy and confocal scanning laser microscopy.Four types of secondary austenite(γ2)morphologies including partially transformed austenite,grain boundary austenite,Widmannstätten austenite(WA)and intragranular austenite could be formed during cooling after solution treatment.It was concluded that secondary austenite morphology was mainly dependent on cooling rates.Two mechanisms of WA formation were proposed.WA nucleated at grain boundary of ferrite or at the formed phase boundary.Transmission electron microscopy(TEM)analysis displayed that WA grew in parallel to the ferrite.The effects of Cr_(2)N on secondary austenite precipitation were discussed in detail.Once Cr_(2)N was involved,a mechanism was proposed that secondary austenite formed by element diffusion,leading to the migration of the austenite–ferrite interface.Cr_(2)N acted as the nucleation sites forγ2 and provided the nitrogen for the transformation;meanwhile,the precipitation of Cr_(2)N during the rapid cooling was captured by TEM.A process of nucleation followed by diffusion was concluded to be the formation of secondary austenite with no Cr_(2)N precipitated.The decomposition of secondary austenite was also studied,which was found to be a diffusion mechanism followed by displacement in connection with the element distribution.
文摘Background: Ischemic stroke accounts for approximately 80% of all cases of stroke and has the highest rates of morbidity,disability,mortality,and recurrence. The neutrophil-to-lymphocyte ratio (NLR) is a novel,feasible marker representing an integrated response to inflammation. The purpose of the current review is to evaluate all available evidence from clinical observational trials about the relationships between NLR and ischemic stroke. Methods: We searched PubMed,Embase,and CNKI for clinical observational trials on NLR published up to August 1,2018,and made a brief summary about the predictive value of the correlation between NLR and ischemic stroke. Results: A high NLR is associated with increased risk of developing stroke and is a new addition to the traditional risk factors of atrial fibrillation and carotid artery stenosis. NLR on admission is an independent predictor of short- and long-term mortality in patients with acute ischemic stroke. In patients receiving recombinant tissue plasminogen activator or endovascular treatments,high NLR was reported with higher mortality or major disability. Conclusion: NLR provides an easy,useful method to predict the incidence,severity,and prognosis of ischemic stroke;thus,it can emerge as a new potential target for anti-inflammatory treatment and development of therapeutic strategies.
