There are many brands of activated alumina powders in the market and the products from different manufacturers exist subtle differences. In this work, four brands of activated alumina powder which are the mainstream p...There are many brands of activated alumina powders in the market and the products from different manufacturers exist subtle differences. In this work, four brands of activated alumina powder which are the mainstream products in China with the same marked particle size of 2-3 μm were added to corundum castables to investigate the effect of different activated alumina powder on properties of corundum castables. It is found that the multi-peak distribution, round-shape particle,low impurities content of alumina powder are of great benefit to the improvement of the overall performance of castables.Obvious CA6 frame structure formed in castables matrix is conductive to improving the thermal shock resistance and high temperature strength of castables. One kind of domestic alumina micropowder studied in this work has good application value and prospect in corundum castables because of the excellent comprehensive performance.展开更多
To study the effect of the particle size of industrial alumina powder on the properties of active alumina micropowder(α-Al_(2)O_(3) micropowder),the fine powders with the median diameter of 50,30,10,and 5 pm,respecti...To study the effect of the particle size of industrial alumina powder on the properties of active alumina micropowder(α-Al_(2)O_(3) micropowder),the fine powders with the median diameter of 50,30,10,and 5 pm,respectively,were obtained by grinding industrial alumina powder(the median diameter of 80 pm),and the active alumina micropowders were prepared by firing the industrial alumina powders before and after grinding at 1320℃ for 5 h.The effect of the particle size of the industrial alumina powder on the microstructure and properties of the active alumina micropowder was researched.The results indicate that the initial particle size of the industrial alumina powder has a great influence on the grain morphology of the active alumina micropowder;when the median diameter is larger than 30 pm,the α-Al_(2)O_(3) grains show wormlike aggregates state after calcination and when it is around or less than 10 pm,the α-Al_(2)O_(3) are round,spherical and well dispersed grains with the particle size of 0.3-1.0 pm.With the initial particle size of the industrial alumina powder decreasing,the α-Al_(2)O_(3) phase transition rate increases and the true density gradually increases;moreover,the α-Al_(2)O_(3) powder shows better dispersity and flowability.展开更多
Objective To explore the relationship of phospholipase A2 receptor(PLA2R)expression in renal tissue with clinical characteristics,prognosis of idiopathic membranous nephropathy(IMN)patients.Methods 134 patients diagno...Objective To explore the relationship of phospholipase A2 receptor(PLA2R)expression in renal tissue with clinical characteristics,prognosis of idiopathic membranous nephropathy(IMN)patients.Methods 134 patients diagnosed as nephropathy proven by biopsy were selected as subjects of this research,including 98 patients with IMN patients,10 patients with secondary membranous nephropathy and 26 patients with other renal glomerular diseases.The expression of PLA2R antigen in renal tissue was detected by immuno-fluorescence chemistry staining.Results The positive rate of renal PLA2R expression in IMN patients was higher than that in SMN patients(91.84% vs 40.00%,P<0.01),whereas there was no expression in other glomerular diseases.The PLA2R negative group was mainly stage I membranous nephropathy,and positive group was mainly in stage Ⅱ.The distribution of pathological stage between the two groups was statistically significant(P<0.01).Compared with the positive group,the negative group was manifested with higher eGFR[(115.91±23.32)ml · min-1 ·(1.73 m^2)-1vs(94.06±27.38)ml·min^-1·(1.73 m^2)^-1,P=0.031],associated with the higher 12-month complete remission rate(87.50% vs 44.07%,P=0.021).Conclusion The expression of PLA2R antigen in renal tissue plays an important role in the diagnosis,disease evaluation and prognosis of IMN.The negative PLA2R in kidney tissue of IMN may indicate a good clinical prognosis.展开更多
文物古迹是北京历史文化的“金名片”,全面掌握区域文物古迹时空分布特征与规律,是推动其系统保护的基础和前提。对此,基于北京市全国第三次文物普查和北京市文物局统计数据,利用图示分析法和地理信息系统(Geographic Information Syste...文物古迹是北京历史文化的“金名片”,全面掌握区域文物古迹时空分布特征与规律,是推动其系统保护的基础和前提。对此,基于北京市全国第三次文物普查和北京市文物局统计数据,利用图示分析法和地理信息系统(Geographic Information System,GIS),重点探究了区域文物古迹的空间、类型和年代分布特征与规律,以期为其保护利用提供参考借鉴。研究表明:北京文物古迹空间分布规律,中心城区文物古迹密度最高;呈大聚集、成片区的格局,成片分布于山前平原、盆地和谷地等平坦地带,并明显聚集于三大文化带和几个典型区域。类型多样,涵盖文物古迹所有遗产形态,以古建筑数量最多,约占总量41%;年代和空间分布根据文物类型而不同。年代跨度大、完整性和聚集性强,以明清两代数量最多,约占总量60%;随着年代变迁,类型由古遗址、古墓葬向古建筑和近现代文物转变,空间分布由周边山区向中心城区过渡。展开更多
文摘There are many brands of activated alumina powders in the market and the products from different manufacturers exist subtle differences. In this work, four brands of activated alumina powder which are the mainstream products in China with the same marked particle size of 2-3 μm were added to corundum castables to investigate the effect of different activated alumina powder on properties of corundum castables. It is found that the multi-peak distribution, round-shape particle,low impurities content of alumina powder are of great benefit to the improvement of the overall performance of castables.Obvious CA6 frame structure formed in castables matrix is conductive to improving the thermal shock resistance and high temperature strength of castables. One kind of domestic alumina micropowder studied in this work has good application value and prospect in corundum castables because of the excellent comprehensive performance.
文摘To study the effect of the particle size of industrial alumina powder on the properties of active alumina micropowder(α-Al_(2)O_(3) micropowder),the fine powders with the median diameter of 50,30,10,and 5 pm,respectively,were obtained by grinding industrial alumina powder(the median diameter of 80 pm),and the active alumina micropowders were prepared by firing the industrial alumina powders before and after grinding at 1320℃ for 5 h.The effect of the particle size of the industrial alumina powder on the microstructure and properties of the active alumina micropowder was researched.The results indicate that the initial particle size of the industrial alumina powder has a great influence on the grain morphology of the active alumina micropowder;when the median diameter is larger than 30 pm,the α-Al_(2)O_(3) grains show wormlike aggregates state after calcination and when it is around or less than 10 pm,the α-Al_(2)O_(3) are round,spherical and well dispersed grains with the particle size of 0.3-1.0 pm.With the initial particle size of the industrial alumina powder decreasing,the α-Al_(2)O_(3) phase transition rate increases and the true density gradually increases;moreover,the α-Al_(2)O_(3) powder shows better dispersity and flowability.
文摘Objective To explore the relationship of phospholipase A2 receptor(PLA2R)expression in renal tissue with clinical characteristics,prognosis of idiopathic membranous nephropathy(IMN)patients.Methods 134 patients diagnosed as nephropathy proven by biopsy were selected as subjects of this research,including 98 patients with IMN patients,10 patients with secondary membranous nephropathy and 26 patients with other renal glomerular diseases.The expression of PLA2R antigen in renal tissue was detected by immuno-fluorescence chemistry staining.Results The positive rate of renal PLA2R expression in IMN patients was higher than that in SMN patients(91.84% vs 40.00%,P<0.01),whereas there was no expression in other glomerular diseases.The PLA2R negative group was mainly stage I membranous nephropathy,and positive group was mainly in stage Ⅱ.The distribution of pathological stage between the two groups was statistically significant(P<0.01).Compared with the positive group,the negative group was manifested with higher eGFR[(115.91±23.32)ml · min-1 ·(1.73 m^2)-1vs(94.06±27.38)ml·min^-1·(1.73 m^2)^-1,P=0.031],associated with the higher 12-month complete remission rate(87.50% vs 44.07%,P=0.021).Conclusion The expression of PLA2R antigen in renal tissue plays an important role in the diagnosis,disease evaluation and prognosis of IMN.The negative PLA2R in kidney tissue of IMN may indicate a good clinical prognosis.
文摘文物古迹是北京历史文化的“金名片”,全面掌握区域文物古迹时空分布特征与规律,是推动其系统保护的基础和前提。对此,基于北京市全国第三次文物普查和北京市文物局统计数据,利用图示分析法和地理信息系统(Geographic Information System,GIS),重点探究了区域文物古迹的空间、类型和年代分布特征与规律,以期为其保护利用提供参考借鉴。研究表明:北京文物古迹空间分布规律,中心城区文物古迹密度最高;呈大聚集、成片区的格局,成片分布于山前平原、盆地和谷地等平坦地带,并明显聚集于三大文化带和几个典型区域。类型多样,涵盖文物古迹所有遗产形态,以古建筑数量最多,约占总量41%;年代和空间分布根据文物类型而不同。年代跨度大、完整性和聚集性强,以明清两代数量最多,约占总量60%;随着年代变迁,类型由古遗址、古墓葬向古建筑和近现代文物转变,空间分布由周边山区向中心城区过渡。
