This work mainly focuses on the mineralogical study of particulate matter(PM10) in Beijing. Samples were collected on polycarbonate filter from April, 2002 to March, 2003 in Beijing urban area. Scanning electronic m...This work mainly focuses on the mineralogical study of particulate matter(PM10) in Beijing. Samples were collected on polycarbonate filter from April, 2002 to March, 2003 in Beijing urban area. Scanning electronic microscopy coupled with energy dispersive X-ray(SEM/EDX) was used to investigate individual mineral particles in Beijing PM10. 1454 individual mineral particulates from 48 samples were analysed by SEM/EDX. The results revealed that mineral particulates were complex and heterogeneous. 38 kinds of minerals in PM10 were identified. The clay minerals, of annual average percentage of 30.1%, were the main composition among the identified minerals, and illite/smectite was the main composition in clay minerals, reaching up to 35%. Annual average percentage of quartz, calcite, compound particulates, carbonates were 13.5%, 10.9%, 11.95%, 10.31%, respectively. Annual average percentage less than 10% were gypsum, feldspar, dolomite, and so on. Fluorite, apatite, halite, barite and chloridize zinc(ZnCl2) were firstly identified in Beijing PM10. Sulfurization was found on surface of mineral particles, suggested extensive atmospheric reaction in air during summer.展开更多
Background Turbulent shear stress (TSS) plays an important role in the research of fluid dynamics of heart valves. This study aimed to perform a quantitative study of TSS downstream of porcine artificial mitral valv...Background Turbulent shear stress (TSS) plays an important role in the research of fluid dynamics of heart valves. This study aimed to perform a quantitative study of TSS downstream of porcine artificial mitral valves in order to verify the correlation of hot-film anemometry (HFA) and Doppler echocardiography combined with computer-aided image analysis for the detection of TSS. Methods A porcine model of mitral valve replacement was established. HFA and Doppler ultrasound techniques were used to directly and indirectly measure TSS-relevant parameters of the artificial mitral valve following different mitral valve replacements: different approaches were used to reserve the subvalvular apparatus of the mitral valve. A correlation analysis was then carried out. Results There was a significant correlation between the HFA and Doppler ultrasound combined with computer-aided image analysis of the TSS at the same time and at the same site. No significant difference was found in the TSS measured by the two methods. Conclusions Compared with HFA, Doppler echocardiography combined with computer-aided image analysis is a safe, non-invasive, and real-time method that enables accurate and quantitative detection of TSS downstream in vivo, objectively reflecting the flow field downstream of the artificial mitral valve. Doppler ultrasound combined with computer- aided image analysis can be employed for quantitatively evaluating the downstream hemodynamic performance of the mitral valve.展开更多
基金The National Natural Science Foundation of China(No.40275040) and the Shanghai Leading Academic Disciplines(No. T0105)
文摘This work mainly focuses on the mineralogical study of particulate matter(PM10) in Beijing. Samples were collected on polycarbonate filter from April, 2002 to March, 2003 in Beijing urban area. Scanning electronic microscopy coupled with energy dispersive X-ray(SEM/EDX) was used to investigate individual mineral particles in Beijing PM10. 1454 individual mineral particulates from 48 samples were analysed by SEM/EDX. The results revealed that mineral particulates were complex and heterogeneous. 38 kinds of minerals in PM10 were identified. The clay minerals, of annual average percentage of 30.1%, were the main composition among the identified minerals, and illite/smectite was the main composition in clay minerals, reaching up to 35%. Annual average percentage of quartz, calcite, compound particulates, carbonates were 13.5%, 10.9%, 11.95%, 10.31%, respectively. Annual average percentage less than 10% were gypsum, feldspar, dolomite, and so on. Fluorite, apatite, halite, barite and chloridize zinc(ZnCl2) were firstly identified in Beijing PM10. Sulfurization was found on surface of mineral particles, suggested extensive atmospheric reaction in air during summer.
基金This study was supported by grants from the National Natural Science Foundation of China (No. 30860297) and the United Specialized Foundation of Science and Technology Agency of Yunnan Province and Kunming Medical University (No. 2011FB 185).
文摘Background Turbulent shear stress (TSS) plays an important role in the research of fluid dynamics of heart valves. This study aimed to perform a quantitative study of TSS downstream of porcine artificial mitral valves in order to verify the correlation of hot-film anemometry (HFA) and Doppler echocardiography combined with computer-aided image analysis for the detection of TSS. Methods A porcine model of mitral valve replacement was established. HFA and Doppler ultrasound techniques were used to directly and indirectly measure TSS-relevant parameters of the artificial mitral valve following different mitral valve replacements: different approaches were used to reserve the subvalvular apparatus of the mitral valve. A correlation analysis was then carried out. Results There was a significant correlation between the HFA and Doppler ultrasound combined with computer-aided image analysis of the TSS at the same time and at the same site. No significant difference was found in the TSS measured by the two methods. Conclusions Compared with HFA, Doppler echocardiography combined with computer-aided image analysis is a safe, non-invasive, and real-time method that enables accurate and quantitative detection of TSS downstream in vivo, objectively reflecting the flow field downstream of the artificial mitral valve. Doppler ultrasound combined with computer- aided image analysis can be employed for quantitatively evaluating the downstream hemodynamic performance of the mitral valve.