目的研究一种绿色环保的表面处理方法,以提高镁合金的耐蚀性。方法采用化学浸泡法,以硝酸钇为成膜物质,在AZ31B镁合金表面成功制备一种新型稀土盐转化膜,并以氧化石墨烯为阻隔剂对该转化膜进行复合掺杂。采用扫描电镜(SEM)对膜层的表面...目的研究一种绿色环保的表面处理方法,以提高镁合金的耐蚀性。方法采用化学浸泡法,以硝酸钇为成膜物质,在AZ31B镁合金表面成功制备一种新型稀土盐转化膜,并以氧化石墨烯为阻隔剂对该转化膜进行复合掺杂。采用扫描电镜(SEM)对膜层的表面形貌进行观察,采用析氢实验和电化学测试对不同试样在3.5%Na Cl溶液中的耐蚀性进行了研究。结果镁合金钇盐转化膜表面平整均一,覆盖良好。氧化石墨烯掺杂后的钇盐膜层表面出现了大小不均一的瘤状物质,膜层完整,未出现裂痕。析氢实验结果显示,经过处理的转化膜试样可以极大地抑制腐蚀反应的发生。由极化曲线可知,钇盐转化膜的存在使镁合金的腐蚀电位发生了明显正移,正移了150 m V;而氧化石墨烯掺杂的钇盐膜层的腐蚀电位相对于掺杂前变化不大,但其腐蚀电流密度是掺杂前的1/28。电化学交流阻抗谱的测试结果显示,氧化石墨烯掺杂钇盐转化膜的电荷转移电阻最大,Rct为2485?·cm2;钇盐转化膜的电荷转移电阻次之,Rct为1224?·cm2。两者的电荷转移电阻相对于未经处理的镁合金都有明显提升。结论钇盐转化膜可以明显提高AZ31B镁合金的耐蚀性,氧化石墨烯的加入可以进一步提高转化膜层的耐蚀性。展开更多
Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines...Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength, which are under different conditions, including pure bending and bending combined with internal pressure. Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes. In parametric analysis, a series of parameters,including pipe geometrical dimension, pipe material properties and internal pressure, were selected to study their influences on the critical bending moment, critical compressive stress and critical compressive strain of pipes.Especially the hardening exponent of pipe material was introduced to the parameter analysis by using the Ramberg–Osgood constitutive model. Results showed that geometrical dimensions, material and internal pressure can exert similar effects on the critical bending moment and critical compressive stress, which have different, even reverse effects on the critical compressive strain. Based on these analyses, more accurate design models of critical bending moment and critical compressive stress have been proposed for high-strength pipelines under bendingconditions, which provide theoretical methods for highstrength pipeline engineering.展开更多
Background The result would be disastrous if the superior pulmonary sulcus tumor （Pancoast tumor） was misdiagnosed as degenerative cervical spine diseases. The aim of this study was to investigate the differential d...Background The result would be disastrous if the superior pulmonary sulcus tumor （Pancoast tumor） was misdiagnosed as degenerative cervical spine diseases. The aim of this study was to investigate the differential diagnosis methods of cervical radiculopathy and superior pulmonary sulcus tumor. Methods Clinical manifestations, physical, and radiological findings of 10 patients, whose main complaints were radiating shoulder and arm pain and later were diagnosed with superior pulmonary sulcus tumor, were reviewed and compared with those of cervical radiculopathy. Results Superior pulmonary sulcus tumor patients have shorter mean history and fewer complaints of neck pain or limitation of neck movement. Physical examination showed almost normal cervical spine range of motion. Spurling＇s neck compression test was negative in all patients. Anteroposterior cervical radiographs showed the lack of pulmonary air at the top of the affected lung in all cases and first rib encroachment in one case. The diagnosis of superior pulmonary sulcus tumor can be further confirmed by CT and MRI. Conclusions By the method of combination of history, physical examination, and radiological findings, superior pulmonary sulcus tumor can be efficiently differentiated from cervical radiculopathy. Normal motion range of the cervical spine, negative Spurling＇s neck compression test, and the lack of pulmonary air at the top of the affected lung in anteroposterior cervical radiographs should be considered as indications for further chest radiograph examinations.展开更多
目的检索并获取临床护理交接班的最佳证据,为医务人员临床实践提供参考。方法根据“6 S”证据模型,计算机检索BMJ Best Practice、Up To Date、Cochrane library、JBI、NICE、Pub Med、Web of Science、EMbase、CINAHL、中国知网、中国...目的检索并获取临床护理交接班的最佳证据,为医务人员临床实践提供参考。方法根据“6 S”证据模型,计算机检索BMJ Best Practice、Up To Date、Cochrane library、JBI、NICE、Pub Med、Web of Science、EMbase、CINAHL、中国知网、中国生物医学文献数据库、万方、维普等数据库关于护理交接的相关证据,检索时限为建库至2022年2月19日。由2~5名研究者独立对相关文献进行质量评价、证据提取与汇总。结果纳入文献20篇(1篇指南、3篇证据总结、13篇系统评价、3篇最佳循证实践),提取证据72条,归纳为6个类别35条最佳证据,含标准化/结构化交接、交接场景、交接管理、交接培训、交接实施和交接质控监督与反馈。结论本研究总结了护理交接班最佳证据,旨在为临床护理交接提供循证依据,但在交接过程中应根据医院及科室具体情况,选择性地使用相关证据,以提高临床护理交接质量。展开更多
文摘目的研究一种绿色环保的表面处理方法,以提高镁合金的耐蚀性。方法采用化学浸泡法,以硝酸钇为成膜物质,在AZ31B镁合金表面成功制备一种新型稀土盐转化膜,并以氧化石墨烯为阻隔剂对该转化膜进行复合掺杂。采用扫描电镜(SEM)对膜层的表面形貌进行观察,采用析氢实验和电化学测试对不同试样在3.5%Na Cl溶液中的耐蚀性进行了研究。结果镁合金钇盐转化膜表面平整均一,覆盖良好。氧化石墨烯掺杂后的钇盐膜层表面出现了大小不均一的瘤状物质,膜层完整,未出现裂痕。析氢实验结果显示,经过处理的转化膜试样可以极大地抑制腐蚀反应的发生。由极化曲线可知,钇盐转化膜的存在使镁合金的腐蚀电位发生了明显正移,正移了150 m V;而氧化石墨烯掺杂的钇盐膜层的腐蚀电位相对于掺杂前变化不大,但其腐蚀电流密度是掺杂前的1/28。电化学交流阻抗谱的测试结果显示,氧化石墨烯掺杂钇盐转化膜的电荷转移电阻最大,Rct为2485?·cm2;钇盐转化膜的电荷转移电阻次之,Rct为1224?·cm2。两者的电荷转移电阻相对于未经处理的镁合金都有明显提升。结论钇盐转化膜可以明显提高AZ31B镁合金的耐蚀性,氧化石墨烯的加入可以进一步提高转化膜层的耐蚀性。
基金supported by the National ScienceTechnology Support Plan Projects of China, under Award No. 2015BAK16B02
文摘Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load. This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength, which are under different conditions, including pure bending and bending combined with internal pressure. Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes. In parametric analysis, a series of parameters,including pipe geometrical dimension, pipe material properties and internal pressure, were selected to study their influences on the critical bending moment, critical compressive stress and critical compressive strain of pipes.Especially the hardening exponent of pipe material was introduced to the parameter analysis by using the Ramberg–Osgood constitutive model. Results showed that geometrical dimensions, material and internal pressure can exert similar effects on the critical bending moment and critical compressive stress, which have different, even reverse effects on the critical compressive strain. Based on these analyses, more accurate design models of critical bending moment and critical compressive stress have been proposed for high-strength pipelines under bendingconditions, which provide theoretical methods for highstrength pipeline engineering.
文摘Background The result would be disastrous if the superior pulmonary sulcus tumor （Pancoast tumor） was misdiagnosed as degenerative cervical spine diseases. The aim of this study was to investigate the differential diagnosis methods of cervical radiculopathy and superior pulmonary sulcus tumor. Methods Clinical manifestations, physical, and radiological findings of 10 patients, whose main complaints were radiating shoulder and arm pain and later were diagnosed with superior pulmonary sulcus tumor, were reviewed and compared with those of cervical radiculopathy. Results Superior pulmonary sulcus tumor patients have shorter mean history and fewer complaints of neck pain or limitation of neck movement. Physical examination showed almost normal cervical spine range of motion. Spurling＇s neck compression test was negative in all patients. Anteroposterior cervical radiographs showed the lack of pulmonary air at the top of the affected lung in all cases and first rib encroachment in one case. The diagnosis of superior pulmonary sulcus tumor can be further confirmed by CT and MRI. Conclusions By the method of combination of history, physical examination, and radiological findings, superior pulmonary sulcus tumor can be efficiently differentiated from cervical radiculopathy. Normal motion range of the cervical spine, negative Spurling＇s neck compression test, and the lack of pulmonary air at the top of the affected lung in anteroposterior cervical radiographs should be considered as indications for further chest radiograph examinations.
文摘目的检索并获取临床护理交接班的最佳证据,为医务人员临床实践提供参考。方法根据“6 S”证据模型,计算机检索BMJ Best Practice、Up To Date、Cochrane library、JBI、NICE、Pub Med、Web of Science、EMbase、CINAHL、中国知网、中国生物医学文献数据库、万方、维普等数据库关于护理交接的相关证据,检索时限为建库至2022年2月19日。由2~5名研究者独立对相关文献进行质量评价、证据提取与汇总。结果纳入文献20篇(1篇指南、3篇证据总结、13篇系统评价、3篇最佳循证实践),提取证据72条,归纳为6个类别35条最佳证据,含标准化/结构化交接、交接场景、交接管理、交接培训、交接实施和交接质控监督与反馈。结论本研究总结了护理交接班最佳证据,旨在为临床护理交接提供循证依据,但在交接过程中应根据医院及科室具体情况,选择性地使用相关证据,以提高临床护理交接质量。
