Mapping CD20 molecules on the lymphoma cell surface using atomic force microscopy

Atomic force microscopy (AFM) was used to locate CD20 molecules on the surface of lymphoma Raji cells. Rituximab (a monoclonal antibody against CD20) molecules were linked onto the AFM tip via a polyethylene glycol (PEG) linker. Raji cells were adsorbed onto glass slides coated with poly-L-lysine. First, the CD20 distribution in a local area of the cell surface was visualized using the AFM lift scan mode. Second, 16 × 16 force curves were obtained from the same cell area to construct the CD20-rituximab binding force map. Finally, free rituximab was added to block the CD20 molecules on the cell surface and the lift phase image and CD20-rituximab force map were obtained again. The experimental results indicated that when the lift height was greater than the length of the PEG linker, no recognition sites were observed in the lift phase image. However, as the lift height decreased to the length of the PEG linker, some recognition sites were observed in the lift phase image and these sites were generally consistent with the pixels in the force map. After blocking, both the recognition sites in the lift phase image and the gray pixels in the binding force map decreased markedly. These results can improve our understanding of the distribution of protein molecules on the cell surface and facilitate further investigations into cellular functions.     

Features of intervertebral disc degeneration in rat’s aging process

Objective: The age-related change is important part of degenerative disc disease. However, no appropriate animal model or objective evaluation index is available. This study aimed to investigate the features of intervertebral disc degeneration in aging process of rats. Methods: 22-month-old Sprague-Dawley (SD) rats were used as spontaneously occurring intervertebral disc degeneration models and 6-month-old rats as young controls. Expression of collagen types II and X was measured by immunohistochemistry. Degenerations of intervertebral discs were scored according to Miyamoto’s method. Numbers and areas of afferent vascular buds were measured. The thicknesses of non-calcified and calcified layers were measured and statistically analyzed. Results: There were less collagen type II expression and more collagen type X expression in the calcified layer of the cartilage endplates and nucleus pulposus in the rats of the aged group than in the young control. There were fewer and smaller afferent vascular buds in the rats of the aged group than in the young control group. The ratio of the non-calcified to the calcified layers in the rats of the aged group significantly decreased, compared with that of the young control group (P<0.01). Conclusion: Rats can spontaneously establish intervertebral disc age-related degeneration. The expression of collagen types II and X, numbers and areas of afferent vascular buds, the ratio of the non-calcified to the calcified layers, and water and glycosaminoglycan contents in the nucleus pulposus are sensitive indexes of intervertebral disc degeneration.     

工业炉旋风预燃器煤粉颗粒运动轨迹

在预燃器冷态模型流场内，考虑气流曳引力、重力和Magnus旋转升力，建立颗粒的运动微分方程，并考察颗粒与壁面相互碰撞过程，采用龙格库塔法进行数值求解，得到不同粒径的颗粒在4种流场工部中的运动和停留时间，经计算，还可得出以下结论。⑴颗粒的运动轨迹主要受气相流场分布、颗粒粒径和颗粒初始速度等因素的影响。⑵颗粒粒径较小时，可以忽略上升力和重力的影响，但大颗粒与壁面碰撞后，必须连同考虑颗粒旋转及Magnus升力的作用。⑶选择合适的入口-二次风量比（Q2/Q1）和颗粒的初始速度，可延长颗粒在预燃器内的停留时间，能分离大于30μm的颗粒，该结果能为粉煤旋风预燃器的优化设计提供理论依据。     

基于RTCC原理的精确定时研究与应用

介绍了一种基于RTCC的精确定时原理与方法，通过对PIC单片机其参数合理的设置、程序结构的合理安排以及配套算法的合理应用，实现了误差为零的精确定时方法，弥补了PIC系列特别是低端无中断MCU的精确定时的空白．并将此方法成功应用于实际工业环境中，取得了满意的结果．     

地铁车辆段DMS系统深化设计探讨

针对深圳轨道交通4号线二期工程龙华车辆段深化设计的实际情况，详细介绍了机电设备管理系统（DMS）在项目深化设计中的整体思路，分析了系统在深化设计阶段遇到的技术难点、解决办法及需要注意的事项，对其他类似项目在深化设计阶段的实施具有较好的参照意义。     

英语汉语思维模式差异对跨文化交际的影响

英汉思维差异的形成是由其语言本身以及其使用的文化背景和主体产生的.忽视这种差异会导致跨文化交际的失误,从而加深文化冲突.因此必须了解这种差异性并找到处理跨文化交际差异性的方法,最终避免交际中语用失误和文化冲突.     

浅析元白判文

唐代中期，元白的判文盛行一时，他们的判文在内容和风格上极为相似。并被广大学子引为判文之圭臬，竞相仿作。究其原因，无非是时代的因素和元白判文的精妙所造就。文章从元白判文的内容和艺术特色等方面进行了研究，从而揭示了元白判文盛行的原因所在。     

无意识笼罩下的俄狄浦斯情结——《雷雨》中男性人物的心理分析

用精神分析中的无意识方法分析了《雷雨》中三个男性人物的行为和心理，从中审视作者的创作心理，揭示了二者的内在联系。     

山西省黄土风情旅游研究

文章利用层次分析法这一定性和定量相结合的方法对山西省黄土风情旅游进行了分析,得出山西黄土风情旅游资源品质高,特征独特文化底蕴深厚,奇特度、美感度较高,但山西的旅游环境和交通设施以及人员素质都需提高的结论.文章在此基础上提出了对策,为山西旅游业可持续发展提供了思路和依据.     

基于规范文本的特征词提取技术研究

文本特征词提取是一种提炼文本重要信息的实用技术,同时也为文本聚类、自动分类、信息抽取等相关课题提供了技术支持。在规范文本上,利用文本篇章结构的特征,以此为基础设计了一个特征词的加权函数,综合考虑了词频、词长和位置因子,并对比分析了各种位置因子对系统的贡献度。