Particulate matter(PM)capture tests were carried out on clean diesel particulate filters(DPFs)under different loads(25%,50%,75%and 100%).DPFs were regenerated by a non-thermal plasma(NTP)injection device.Raman spectro...Particulate matter(PM)capture tests were carried out on clean diesel particulate filters(DPFs)under different loads(25%,50%,75%and 100%).DPFs were regenerated by a non-thermal plasma(NTP)injection device.Raman spectroscopy and x-ray photoelectron spectroscopy were used to investigate changes in the microstructure and element occurrence state of the sediment in DPF channel before and after regeneration.The order of the PM samples decreased before NTP treatment as the load increased;the amorphous carbon content was high,and the oxidationactivity was higher.After NTP treatment,the carbon atoms at the edge of the microcrystalline structure in the ash-PM samples were oxidized,and the structure was reorganized;in addition,the amorphous carbon content decreased,and the structure was more diversified.Before NTP,the C element of PM samples was the main component,and the content of the O element was relatively low.The C element occurred in the form of C–C,C–OH,and O–C=O functional groups,and O atoms were mainly combined with C–O.After NTP,the content of Na,P,S,Ca,and other inorganic elements in ash-PM samples was prominent because C atoms were removed by NTP active substances.There were two forms of S element occurrence(SO42-and SO32-);the proportion of SO42-was approximately 40%,and the proportion of SO32-was approximately60%.Study of the microstructure and element occurrence of the residues in the DPF channels improved our understanding of the mechanism of the low-temperature regeneration of DPFfrom NTP.展开更多
The resistivities of vanadium-doped semi-insulating 4H-SiC wafers were measured by a contactless resistivity measurement system. Anomalous resistivity was found in semi-insulating 4H-SiC wafer. Raman spectra of semi-i...The resistivities of vanadium-doped semi-insulating 4H-SiC wafers were measured by a contactless resistivity measurement system. Anomalous resistivity was found in semi-insulating 4H-SiC wafer. Raman spectra of semi-insulating4H-SiC wafer indicated that the anomalous resistivity was caused by polytype inclusion. Based on the activation energies of different SiC polytypes calculated from resistivity versus temperature data measured by COREMA-VT, the resistivities in the vanadium-doped semi-insulating 4H-SiC wafer with 6H polytype inclusion were calculated. The calculated resistivities are quite consistent with the measured resistivities. Furthermore, the compensation mechanism for the formation of anomalous resistivity was proposed.展开更多
目的:基于文献计量学软件CiteSpace和VOSviewer探讨角膜塑形镜领域的研究现状及热点。方法:文献计量学研究。于2024年11月检索中国知网数据库及Web of Science核心数据库2005—2024年角膜塑形镜相关的文献。采用Endnote X9对纳入文献进...目的:基于文献计量学软件CiteSpace和VOSviewer探讨角膜塑形镜领域的研究现状及热点。方法:文献计量学研究。于2024年11月检索中国知网数据库及Web of Science核心数据库2005—2024年角膜塑形镜相关的文献。采用Endnote X9对纳入文献进行管理核对;运用Microsoft Office Excel 2019对数据进行管理统计,并对频次数据制作图形。利用CiteSpace和VOSviewer软件系统构建文献作者、机构、国家或地区、期刊及关键词的可视化图谱并进行分析。结果:最终获取有效中文文献232篇,英文文献887篇。英文文献发表总量明显多于中文文献,中英文发文量自2015年后均呈逐年上升趋势,与角膜塑形镜使用逐渐普及相关。国家或地区之间形成了分别以美国、澳大利亚、中国台湾、英国等为中心的聚类团体,各团体内部科研合作频繁,中国角膜塑形镜发文量大,对角膜塑形镜的关注研究多于国外其他国家,但团体与团体之间相互合作很少,各机构之间的合作力度也相对缺乏。角膜塑形镜相关研究热点主要集中在近视-角膜塑形镜-离焦学说的相关延伸及角膜塑形镜控制近视进展的疗效、安全性、不良反应、后续潜在影响方面。当前角膜塑形镜的研究热点已拓展至视觉质量优化领域,重点聚焦于镜片偏心对视觉成像质量的影响机制及其防控效果的系统评估,同时延伸探索其与视功能训练、低浓度阿托品等联合干预策略的协同作用研究。结论:角膜塑形镜的传统研究聚焦于疗效、安全性及离焦理论验证;当前研究热点转向视觉质量优化(镜片偏心影响机制)及联合疗法(视功能训练或低浓度阿托品)协同效应探索。展开更多
基金supported by National Natural Science Foundation of China(No.51806085)China Postdoctoral Science Foundation(No.2018M642175)+2 种基金Jiangsu Planned Projects for Postdoctoral Research Fund(No.2018K101C)Open Research Subject of Key Laboratory of automotive measurement,control and safety(Xihua University)(No.QCCK2021-007)Graduate Student Innovation Fund Project of Jiangsu Province(No.KYCX213354)。
文摘Particulate matter(PM)capture tests were carried out on clean diesel particulate filters(DPFs)under different loads(25%,50%,75%and 100%).DPFs were regenerated by a non-thermal plasma(NTP)injection device.Raman spectroscopy and x-ray photoelectron spectroscopy were used to investigate changes in the microstructure and element occurrence state of the sediment in DPF channel before and after regeneration.The order of the PM samples decreased before NTP treatment as the load increased;the amorphous carbon content was high,and the oxidationactivity was higher.After NTP treatment,the carbon atoms at the edge of the microcrystalline structure in the ash-PM samples were oxidized,and the structure was reorganized;in addition,the amorphous carbon content decreased,and the structure was more diversified.Before NTP,the C element of PM samples was the main component,and the content of the O element was relatively low.The C element occurred in the form of C–C,C–OH,and O–C=O functional groups,and O atoms were mainly combined with C–O.After NTP,the content of Na,P,S,Ca,and other inorganic elements in ash-PM samples was prominent because C atoms were removed by NTP active substances.There were two forms of S element occurrence(SO42-and SO32-);the proportion of SO42-was approximately 40%,and the proportion of SO32-was approximately60%.Study of the microstructure and element occurrence of the residues in the DPF channels improved our understanding of the mechanism of the low-temperature regeneration of DPFfrom NTP.
基金financially supported by National Basic Research Program of China (No. 2011CB301904)the Natural Science Foundation of China (Nos. 11134006 and 61327808)
文摘The resistivities of vanadium-doped semi-insulating 4H-SiC wafers were measured by a contactless resistivity measurement system. Anomalous resistivity was found in semi-insulating 4H-SiC wafer. Raman spectra of semi-insulating4H-SiC wafer indicated that the anomalous resistivity was caused by polytype inclusion. Based on the activation energies of different SiC polytypes calculated from resistivity versus temperature data measured by COREMA-VT, the resistivities in the vanadium-doped semi-insulating 4H-SiC wafer with 6H polytype inclusion were calculated. The calculated resistivities are quite consistent with the measured resistivities. Furthermore, the compensation mechanism for the formation of anomalous resistivity was proposed.
