To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
The Wuwei Basin is one of the most important oil-and gas-bearing basins in the Meso-Cenozoic basin groups in the Lower Yangtze River region.It has great shale gas resource prospects.The formation mechanism of this bas...The Wuwei Basin is one of the most important oil-and gas-bearing basins in the Meso-Cenozoic basin groups in the Lower Yangtze River region.It has great shale gas resource prospects.The formation mechanism of this basin is poorly studied for lack of constraining data for deep structures.In this paper,a crustal electrical structure model of the Wuwei Basin and the adjacent areas is constructed based on the two-dimensional inversion of a magnetotelluric(MT)sounding profile achieved with the nonlinear conjugate gradient method.The results show that large-scale low-resistance bodies have developed in the underlying middle and lower crust of the Wuwei Basin,and are different from the uplifts on the two sides according to their high-resistance electrical characteristics.The electrical structure and regional geological and geophysical data suggest that the peak zone of the Chuzhou-Chaohu foreland fold-and-thrust belt is located on the east bank of the Yangtze River(Wuhu Section),which,together with the main thrust fault belt in the east,forms a typical thrust structure belt.An early Yanshanian sinistral strike-slip fault developed in the deep part of the Wuwei Basin,which may have controlled the formation and evolution of the basin,whereas the tectonic inversion of the early-developed thrust faults is relatively weak.These findings provide a geophysical basis for future studies of basin tectonic evolution and regional tectonic frameworks.展开更多
目的比较心脏微气泡试验联合超声定位与腔内心电图定位在儿童经外周静脉置入中心静脉导管(peripherally inserted central catheter,PICC)尖端定位中的临床效果,明确微气泡技术的应用优势。方法采用前瞻性随机对照研究,纳入2023年8月至2...目的比较心脏微气泡试验联合超声定位与腔内心电图定位在儿童经外周静脉置入中心静脉导管(peripherally inserted central catheter,PICC)尖端定位中的临床效果,明确微气泡技术的应用优势。方法采用前瞻性随机对照研究,纳入2023年8月至2024年10月某三级甲等医院小儿外科收治的152例PICC置管患儿为研究对象,采用随机数字表法将其分为试验组(微气泡联合超声实时定位)与对照组(腔内心电图定位),每组各76例。比较两组患儿定位成功率、导管尖端准确率、操作时间、并发症发生率及医疗成本。结果试验组在定位成功率、尖端准确率、操作效率、置管成本、家属满意度等方面均优于对照组,而机械性静脉炎、导管相关血栓、血流感染发生率以及2次摄片率方面均低于对照组,差异均有统计学意义(均P<0.05)。结论心脏微气泡联合超声定位技术通过动态可视化监测可提升PICC导管定位精度,在提高操作安全性和降低并发症方面优势显著,尤其适用于需规避放射暴露的儿童群体,具有重要临床应用价值。展开更多
基金National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
基金jointly supported by China Geological Survey(Nos.DD20190030,DD20201164,DD20221638)China National Nonprofit Institute Research(Nos.JKYZD202329,AS2017Y05,JYYWF20180902).
文摘The Wuwei Basin is one of the most important oil-and gas-bearing basins in the Meso-Cenozoic basin groups in the Lower Yangtze River region.It has great shale gas resource prospects.The formation mechanism of this basin is poorly studied for lack of constraining data for deep structures.In this paper,a crustal electrical structure model of the Wuwei Basin and the adjacent areas is constructed based on the two-dimensional inversion of a magnetotelluric(MT)sounding profile achieved with the nonlinear conjugate gradient method.The results show that large-scale low-resistance bodies have developed in the underlying middle and lower crust of the Wuwei Basin,and are different from the uplifts on the two sides according to their high-resistance electrical characteristics.The electrical structure and regional geological and geophysical data suggest that the peak zone of the Chuzhou-Chaohu foreland fold-and-thrust belt is located on the east bank of the Yangtze River(Wuhu Section),which,together with the main thrust fault belt in the east,forms a typical thrust structure belt.An early Yanshanian sinistral strike-slip fault developed in the deep part of the Wuwei Basin,which may have controlled the formation and evolution of the basin,whereas the tectonic inversion of the early-developed thrust faults is relatively weak.These findings provide a geophysical basis for future studies of basin tectonic evolution and regional tectonic frameworks.
文摘目的比较心脏微气泡试验联合超声定位与腔内心电图定位在儿童经外周静脉置入中心静脉导管(peripherally inserted central catheter,PICC)尖端定位中的临床效果,明确微气泡技术的应用优势。方法采用前瞻性随机对照研究,纳入2023年8月至2024年10月某三级甲等医院小儿外科收治的152例PICC置管患儿为研究对象,采用随机数字表法将其分为试验组(微气泡联合超声实时定位)与对照组(腔内心电图定位),每组各76例。比较两组患儿定位成功率、导管尖端准确率、操作时间、并发症发生率及医疗成本。结果试验组在定位成功率、尖端准确率、操作效率、置管成本、家属满意度等方面均优于对照组,而机械性静脉炎、导管相关血栓、血流感染发生率以及2次摄片率方面均低于对照组,差异均有统计学意义(均P<0.05)。结论心脏微气泡联合超声定位技术通过动态可视化监测可提升PICC导管定位精度,在提高操作安全性和降低并发症方面优势显著,尤其适用于需规避放射暴露的儿童群体,具有重要临床应用价值。
