海洋石油平台钢结构在建造过程中,不恰当的焊接方法或不按规定进行的焊接操作,会使焊缝内部产生危害性的焊接缺陷,横向缺陷是其中一种危害性极大的焊接缺陷,但是超声波检验过程往往存在横向缺陷漏检现象,给海洋石油平台的长周期运转带...海洋石油平台钢结构在建造过程中,不恰当的焊接方法或不按规定进行的焊接操作,会使焊缝内部产生危害性的焊接缺陷,横向缺陷是其中一种危害性极大的焊接缺陷,但是超声波检验过程往往存在横向缺陷漏检现象,给海洋石油平台的长周期运转带来安全隐患。为了避免在超声波检验过程中出现横向缺陷漏检现象,该文基于超声波横向缺陷扫查技术,从海洋石油平台钢结构无损检验常用的API RP 2X标准规范着手,分析超声波检验在进行海洋石油平台钢结构焊缝的横向缺陷扫查时,对检验时机、检验对象、扫查灵敏度、扫查方式的相关要求,明确横向缺陷检出的验收准则,提出横向缺陷返修时注意事项和相关参数,总结超声波横向缺陷检验的检出、判定、返修技术。展开更多
Since Isaacson and Wright first reported on the extranodal marginal zone B-cell lymphoma of the stomach in 1983,following studies have clarified many aspects of this disease.We now know that the stomach is the most af...Since Isaacson and Wright first reported on the extranodal marginal zone B-cell lymphoma of the stomach in 1983,following studies have clarified many aspects of this disease.We now know that the stomach is the most affected organ by this disease,and approximately90% of gastric mucosa-associated lymphoid tissue(MALT) lymphomas are related to Helicobacter pylori(H.pylori) infection.This implies that approximately 10% of gastric MALT lymphomas occur independent of H.pylori infection.The pathogenesis of these H.pylori-negative gastric MALT lymphomas remains unclear.To date,there have been several speculations.One possibility is that genetic alterations result in nuclear factor-kappa B(NF-κB) activation.Among these alterations,t(11;18)(q21;q21) is more frequently observed in H.pylori-negative gastric MALT lymphomas,and such translocation results in the synthesis of fusion protein API2-MALT1,which causes canonical and noncanonical NF-κB activation.Another possibility is infection with bacteria other than H.pylori.This could explain why H.pylori eradication therapy can cure some proportions of H.pylori-negative gastric MALT lymphoma patients,although the bacteria responsible for MALT lymphomagenesis are yet to be defined.Recent advances in endoscopy suggest magnifying endoscopy with narrow band imaging as a useful tool for both detecting gastric MALT lymphoma lesions and judging the response to treatment.A certain proportion of H.pylori-negative gastric MALT lymphoma patients respond to eradication therapy; hence,H.pylori eradication therapy could be considered as a first-line treatment for gastric MALT lymphomas regardless of their H.pylori infection status.展开更多
文摘海洋石油平台钢结构在建造过程中,不恰当的焊接方法或不按规定进行的焊接操作,会使焊缝内部产生危害性的焊接缺陷,横向缺陷是其中一种危害性极大的焊接缺陷,但是超声波检验过程往往存在横向缺陷漏检现象,给海洋石油平台的长周期运转带来安全隐患。为了避免在超声波检验过程中出现横向缺陷漏检现象,该文基于超声波横向缺陷扫查技术,从海洋石油平台钢结构无损检验常用的API RP 2X标准规范着手,分析超声波检验在进行海洋石油平台钢结构焊缝的横向缺陷扫查时,对检验时机、检验对象、扫查灵敏度、扫查方式的相关要求,明确横向缺陷检出的验收准则,提出横向缺陷返修时注意事项和相关参数,总结超声波横向缺陷检验的检出、判定、返修技术。
文摘Since Isaacson and Wright first reported on the extranodal marginal zone B-cell lymphoma of the stomach in 1983,following studies have clarified many aspects of this disease.We now know that the stomach is the most affected organ by this disease,and approximately90% of gastric mucosa-associated lymphoid tissue(MALT) lymphomas are related to Helicobacter pylori(H.pylori) infection.This implies that approximately 10% of gastric MALT lymphomas occur independent of H.pylori infection.The pathogenesis of these H.pylori-negative gastric MALT lymphomas remains unclear.To date,there have been several speculations.One possibility is that genetic alterations result in nuclear factor-kappa B(NF-κB) activation.Among these alterations,t(11;18)(q21;q21) is more frequently observed in H.pylori-negative gastric MALT lymphomas,and such translocation results in the synthesis of fusion protein API2-MALT1,which causes canonical and noncanonical NF-κB activation.Another possibility is infection with bacteria other than H.pylori.This could explain why H.pylori eradication therapy can cure some proportions of H.pylori-negative gastric MALT lymphoma patients,although the bacteria responsible for MALT lymphomagenesis are yet to be defined.Recent advances in endoscopy suggest magnifying endoscopy with narrow band imaging as a useful tool for both detecting gastric MALT lymphoma lesions and judging the response to treatment.A certain proportion of H.pylori-negative gastric MALT lymphoma patients respond to eradication therapy; hence,H.pylori eradication therapy could be considered as a first-line treatment for gastric MALT lymphomas regardless of their H.pylori infection status.
