动脉粥样硬化是心血管疾病重要的病理生理基础,延缓和防治动脉粥样硬化对于减少和降低心血管疾病的发病率及病死率具有重要意义。高密度脂蛋白(high density lipoprotein,HDL)通过参与介导胆固醇逆向转运(reverse cholesterol transport...动脉粥样硬化是心血管疾病重要的病理生理基础,延缓和防治动脉粥样硬化对于减少和降低心血管疾病的发病率及病死率具有重要意义。高密度脂蛋白(high density lipoprotein,HDL)通过参与介导胆固醇逆向转运(reverse cholesterol transport,RCT)在抗动脉粥样硬化的形成和进展中发挥了重要作用。Preβ-1高密度脂蛋白(prebeta-1 high density lipoprotein,Preβ-1HDL)作为HDL的一种亚类,是外周细胞移出胆固醇的最初接受体,直接参与了RCT的起始步骤,并在随后的胆固醇酯化及转运中起着重要作用。本文就Preβ-1HDL的结构、代谢及其与心血管疾病的关系作一简要综述。展开更多
以陕西某地钒钛磁铁矿金属化球团为研究对象,基于"磨矿磁选-预酸浸"处理技术,研究了联合处理工艺下钛的富集规律,利用扫描电子显微镜(SEM)和X射线电子衍射仪(XRD)等表征分析了实验前、后样品及富钛料成分和物相组成,确定了&qu...以陕西某地钒钛磁铁矿金属化球团为研究对象,基于"磨矿磁选-预酸浸"处理技术,研究了联合处理工艺下钛的富集规律,利用扫描电子显微镜(SEM)和X射线电子衍射仪(XRD)等表征分析了实验前、后样品及富钛料成分和物相组成,确定了"磨矿磁选-预酸浸"联合工艺下适宜的钛富集工艺参数。结果表明,采用"磨矿磁选-预酸浸"联合工艺技术可以成功实现钛的富集;最佳工艺参数为磨矿粒度74~106μm,磁选强度80 m T,浸出剂盐酸初始浓度4.5 mol/L,浸出温度60℃。在此工艺条件下,得到的富钛料中Ti O2品位达80%以上,可直接作为后续提钛工艺原料。展开更多
There are limited studies in the literature about machinability of bulk metallic glass （BMG）. As a novel and promising structural material, BMG material machining characteristics need to be verified before its utili...There are limited studies in the literature about machinability of bulk metallic glass （BMG）. As a novel and promising structural material, BMG material machining characteristics need to be verified before its utilization. In this paper, the effects of cutting speed, feed rate, depth of cut, abrasive particle size/type on the BMG grinding in dry conditions were experimentally investigated. The experimental evaluations were carried out using cubic boron nitride （CBN） and A1203 cup wheel grinding tools. The parameters were evaluated along with the results of cutting force, temperature and surface roughness measurements, X-ray, scanning electron microscope （SEM） and surface roughness analyse. The results demonstrated that the grinding forces reduced with the increasing cutting speed as specific grinding energy increased. The effect of feed rate was opposite to the cutting speed effect, and increasing feed rate caused higher grinding forces and substantially lower specific energy. Some voids like cracks parallel to the grinding direction were observed at the edge of the grinding tracks. The present investigations on ground surface and grinding chips morphologies showed that material removal and surface formation of the BMG were mainly due to the ductile chip formation and ploughing as well as brittle fracture of some particles from the edge of the tracks. The roughness values obtained with the CBN wheels were found to be acceptable for the grinding operation of the structural materials and were in the rangeof 0.34-0.58 lam. This study also demonstrates that con- ventional A1203 wheel is not suitable for grinding of the BMG in dry conditions.展开更多
文摘动脉粥样硬化是心血管疾病重要的病理生理基础,延缓和防治动脉粥样硬化对于减少和降低心血管疾病的发病率及病死率具有重要意义。高密度脂蛋白(high density lipoprotein,HDL)通过参与介导胆固醇逆向转运(reverse cholesterol transport,RCT)在抗动脉粥样硬化的形成和进展中发挥了重要作用。Preβ-1高密度脂蛋白(prebeta-1 high density lipoprotein,Preβ-1HDL)作为HDL的一种亚类,是外周细胞移出胆固醇的最初接受体,直接参与了RCT的起始步骤,并在随后的胆固醇酯化及转运中起着重要作用。本文就Preβ-1HDL的结构、代谢及其与心血管疾病的关系作一简要综述。
文摘以陕西某地钒钛磁铁矿金属化球团为研究对象,基于"磨矿磁选-预酸浸"处理技术,研究了联合处理工艺下钛的富集规律,利用扫描电子显微镜(SEM)和X射线电子衍射仪(XRD)等表征分析了实验前、后样品及富钛料成分和物相组成,确定了"磨矿磁选-预酸浸"联合工艺下适宜的钛富集工艺参数。结果表明,采用"磨矿磁选-预酸浸"联合工艺技术可以成功实现钛的富集;最佳工艺参数为磨矿粒度74~106μm,磁选强度80 m T,浸出剂盐酸初始浓度4.5 mol/L,浸出温度60℃。在此工艺条件下,得到的富钛料中Ti O2品位达80%以上,可直接作为后续提钛工艺原料。
文摘There are limited studies in the literature about machinability of bulk metallic glass （BMG）. As a novel and promising structural material, BMG material machining characteristics need to be verified before its utilization. In this paper, the effects of cutting speed, feed rate, depth of cut, abrasive particle size/type on the BMG grinding in dry conditions were experimentally investigated. The experimental evaluations were carried out using cubic boron nitride （CBN） and A1203 cup wheel grinding tools. The parameters were evaluated along with the results of cutting force, temperature and surface roughness measurements, X-ray, scanning electron microscope （SEM） and surface roughness analyse. The results demonstrated that the grinding forces reduced with the increasing cutting speed as specific grinding energy increased. The effect of feed rate was opposite to the cutting speed effect, and increasing feed rate caused higher grinding forces and substantially lower specific energy. Some voids like cracks parallel to the grinding direction were observed at the edge of the grinding tracks. The present investigations on ground surface and grinding chips morphologies showed that material removal and surface formation of the BMG were mainly due to the ductile chip formation and ploughing as well as brittle fracture of some particles from the edge of the tracks. The roughness values obtained with the CBN wheels were found to be acceptable for the grinding operation of the structural materials and were in the rangeof 0.34-0.58 lam. This study also demonstrates that con- ventional A1203 wheel is not suitable for grinding of the BMG in dry conditions.
