缺血后处理对大鼠肠缺血-再灌注损伤肠黏膜细胞线粒体的影响

目的探讨缺血后处理对大鼠肠缺血-再灌注损伤肠黏膜细胞线粒体的影响。方法SD大鼠32只随机分为4组(n=8):假手术(S)组、缺血-再灌注(I/R)组、缺血预处理(IPC)组、缺血后处理(I-post)组。应用透射电子显微镜、四甲基偶氮唑蓝(MTT)比色法、激光共聚焦扫描显微镜分别观测各组大鼠肠黏膜细胞线粒体的形态结构、呼吸功能以及线粒体跨膜电位的变化。结果与I/R组相比,I-post组和IPC组大鼠肠黏膜细胞线粒体形态结构改变明显减轻,线粒体呼吸功能和线粒体跨膜电位明显升高(P<0.05);I-post组与IPC组相比,差异无统计学意义(P>0.05)。结论缺血后处理抗大鼠肠缺血-再灌注损伤的作用机制可能与改善肠黏膜细胞线粒体的形态结构和呼吸功能及提高线粒体跨膜电位有关。     

不同提取工艺的酸枣仁油对小鼠镇静催眠作用的影响

目的研究不同工艺(压榨与超临界CO2萃取)所得酸枣仁油对小鼠镇静、催眠作用的影响,并对两种工艺酸枣仁油的作用进行了等效性检验。方法利用光电计数法观察灌胃给予酸枣仁油(1.8 g/kg3、.6 g/kg)对小鼠自主活动的影响,以及重复使用对小鼠自主活动耐受性的影响;利用戊巴比妥钠阈上剂量睡眠实验和阈下剂量睡眠诱导实验,观察两种工艺酸枣仁油(1.8 g/kg、3.6 g/kg)的催眠作用;用地西泮进行平行对照实验。结果压榨与超临界CO2萃取的酸枣仁油均能减少小鼠的自主活动次数;缩短阈上剂量戊巴比妥钠小鼠的睡眠潜伏期,延长睡眠持续期;增加阈下剂量戊巴比妥钠引起的小鼠入睡例数。研究还表明,不同工艺提取的酸枣仁油对小鼠的镇静、催眠作用均具有等效性。重复使用酸枣仁油对小鼠自主活动的抑制作用随用药时间的延长而增强,无耐受现象。结论两种工艺所得酸枣仁油具有等效的镇静、催眠作用,重复使用无耐受现象。     

Toxicity to the normal hemocytes by ALA-PDT for the ex vivo purging of hematopoietic stem cell grafts

Objective To study the toxic effects of 5-amionlevulinic acid-based photodynamic therapy (ALA-PDT) on human peripheral blood mononuclear cells (PBMCs), cord blood mononuclear cells (CBMCs) and peripheral blood stem cells (PBSCs), and furthermore, to understand the possible causes of this response. Methods We used MTT assay to detect the survival rate of PBMCs, CBMCs and PBSCs after treated by ALA-PDT under the optimum experiment conditions with U937 as control;Annexin V-FITC/PI was used to detect the pattern of cell death induced by ALA-PDT. By using flow cytometry, we detected intracellular PpIX fluorescence intensity. Results After ALA-PDT treatment the survival rate of PBMCs had no significant change;however in PBSCs and CBMCs, the survival rate reduced to 70%, and the survival rate of leukemia cell U937 was the lowest, about 30%. After incubation with ALA,except for PBMCs, intraceUuiar PplX fluorescence intensity of the other two kinds of normal haemocytes and U937 increased obviously. These results combined with the flow cytometry suggested that the main pattern of cell death here was apoptosts. Conclusion Under the optimum experiment conditions, ALA-PDT has a slight effect on normal haemocytes but excellent depletions of leukemia cells. Therefore, it can effectively purify autologons bone marrow or stem cell grafts.     

交通影响分析中路网可靠性研究

将路网可靠性的宏观理论微观化,应用到建设项目交通影响分析中,并根据交通影响分析的特性给出了适用性较强的计算方法.结合某商业场所交通影响分析的具体实例,验证了可靠性理论评价分析交通通行状况的合理性,并分析了路网可靠度与饱和度的关系.     

美国城市交通模型立法的历史背景

中国近年来经济快速增长,带来了全面性的城市交通建设.在促进经济发展和社会进步的同时,中国城市交通的发展正面临着许多挑战.如何有效地评估适应新挑战的交通政策措施,并确保交通政策的妥善执行,是中国相关政府部门刻不容缓的课题.通过对已有50年经验的美国运输规划与交通需求预测程序相关立法资料的整理,认为包括数据收集、数据分析、交通需求预测以及替代方法评估的城市交通规划程序可以有效地协助政府部门与专家面对这些新兴的挑战.同时指出,一个定期修订以反映社会发展变化的全国交通建设与发展法,可规范一定比例的资金预算,规定城市交通规划程序与执行的规划组织,并要求制定人员培训计划以有效地执行交通政策.     

Effect of radial interference on torque capacity of press- and shrink-fit gears

Some gears in an automobile transmission have to be mounted by being press-fitted on a shaft instead of splines. The torque capacity of the press-fitted gear will be proportional to the radial interference. The excessive interference, however, will increase the gear radial deformation. In this paper, the press- and shrink-fit and the subsequent torque capacity test were investigated by finite element analysis, theoretically and experimentally. The static and dynamic coefficient of friction were determined.     

基于拓扑优化的油船货舱结构设计研究

研究油船货舱结构拓扑优化设计和普通构件级结构拓扑优化设计的不同点:如设计变量数目多、约束条件多、计算工况多以及计算工况之间应变能差异等。为使普通计算机也能运行舱段结构拓扑优化计算并得到清晰拓扑构型的结果,有必要对舱段拓扑优化设计的优化对象、单元类型、初始板厚、工具方法、约束条件、体积分数、工况加权权值等主要控制参数进行研究。文中给出工程上适用的舱段拓扑优化基结构建模方法和计算方法,并以某一单纵舱壁型VLCC为例,分别采用SIMP法和BESO法给出舱段主要支撑结构拓扑优化的清晰构型。     

An elastic-plastic iceberg material model considering temperature gradient effects and its application to numerical study

To simulate the FPSO-iceberg collision process more accurately, an elastic-plastic iceberg material model considering temperature gradient effects is proposed and applied. The model behaves linearly elastic until it reaches the ‘Tsai-Wu’ yield surfaces, which are a series of concentric elliptical curves of different sizes. Decreasing temperature results in a large yield surface. Failure criteria, based on the influence of accumulated plastic strain and hydrostatic pressure, are built into the model. Based on published experimental data on the relationship between depth and temperature in icebergs, three typical iceberg temperature profiles are proposed. According to these, ice elements located at different depths have different temperatures. The model is incorporated into LS-DYNA using a user-defined subroutine and applied to a simulation of FPSO collisions with different types of iceberg. Simulated area-pressure curves are compared with design codes to validate the iceberg model. The influence of iceberg shape and temperature on the collision process is analyzed. It is indicated that FPSO structural damage not only depends on the relative strength between the iceberg and the structure, but also depends on the local shape of the iceberg.     

基于DCS的机油冷却器液压疲劳试验SCADA系统实现

介绍了一种基于DCS机理的内燃机机油冷却器液压脉动疲劳试验的数据采集与监视控制(SCADA)系统。该系统以IPC为监控管理级,以嵌入式控制器应用于现场直接数字控制级,具有配置灵活、运行可靠、实时性好、试验信息管理和维护方便等特点。介绍了该系统的基本结构、功能设计、工作流程、软硬件平台设计和系统实现过程等。