基于离散元的不同轴截面形状下沙柳颗粒致密成型研究

为研究模具的结构形状对沙柳颗粒致密成型的影响,用离散元软件EDEM建立了沙柳颗粒模型,并将预先用Pro/E创建的3种不同结构的模具先后导入其中,在初始参数、条件设定完成后分别做了匀速压缩模拟。对比研究了3种模具下压缩力的做功,颗粒在竖直和水平方向的形变特征、受力过程,并通过后处理所得数据分析计算了各模具下成型燃料最终获得的密度和能量。结果表明:双弧度、双锥度、单锥度3种模具下压缩过程做功依次为48.86、56.93、66.02 J,燃料总能量分别是40.06、41.54、46.81 J,对应密度为1.23、1.19、1.17 g/cm3;竖直方向双弧度下燃料内部颗粒受到的接触力和发生的形变远大于其他两种模具,水平方向三者颗粒所受的接触力和发生的形变无太大差异;颗粒在3种模具下受到的粘接力均无明显不同,但各自所受的法向粘接力远大于切向粘接力。     

炎症反应与白细胞迁移

人体自我防御中,白细胞定向迁移是先天性免疫必不可少的步骤。然而白细胞在创伤部位的募集也导致了炎症反应的发生。白细胞的移动和它周围微环境的变化精确地调控着一系列级联事件。趋化因子在白细胞迁移过程中起着重要的作用,对介导细胞黏附和迁移的趋化因子的深入研究将有助于对疾病病理状态的了解和控制。     

Effects of Chlamydia pneumoniae infection on adhesion and migration of vascular smooth muscle cells

AIM: To investigate the effects of Chlamydia pneumoniae (C.pn) infection on the adhesion and migration of vascular smooth muscle cells (VSMCs). METHODS: Primary VSMCs, isolated from the aorta of SD rats, was infected with C.pn after the culture and propagation of C.pn in the HEp-2 cells. The morphological characteristics of C.pn inclusions in VSMCs were examined under the fluorescence microscope with acridine orange (AO) staining. The specific DNA fragment of C.pn was identified by polymerase chain reaction (PCR). Cell adhesion assay was performed to investigate the effect of C.pn infection on the adhesion of VSMCs to collagen I. Wound-healing assay and Transwell assay were performed to detect the effects of C.pn infection on VSMCs migration. RESULTS: The C.pn inclusions and infection spots were observed in VSMCs under fluorescence microscope with AO staining. The inclusions were larger than infection spots in volume, but were much lower in count. A 437 bp-specific fragment of C.pn DNA was detected in C.pn-infected VSMCs by PCR. In the cell adhesion assay, the absorbance values in C.pn infection group were far higher than those in control group 2 h after infection (P<0.01). The cell adhesion ratio in C.pn infection group was 134.38%. The migration distance of VSMCs infected with C.pn was significantly longer than that of the control cells 24 h after infection by a wound-healing assay (P<0.05). More migratory VSMCs infected with C.pn for 24 h were found in a Transwell assay than those in control group (P<0.01). CONCLUSION: C.pn infection significantly promotes the adhesion and migration of VSMCs.     

Effect of Aurora protein kinase inhibitor VX-680 on homogeneity adhesion and migration in human hepatoma HepG2 cell

AIM:To study the effect of Aurora protein kinase inhibitor VX-680 on homogeneous adhesion and migration ability in human hepatocellular carcinoma cell line HepG2. METHODS:The HepG2 cell were divided into experimental group and control group, respectively. VX-680 was used in experimental groups at 3 concentrations (3.125 μmol/L group, 6.25 μmol/L group and 12.5 μmol/L group). DMSO was used in the control group. The effects of VX-680 at different concentrations on the adhesion ability of human hepatocellular carcinoma HepG2 cells were observed by cell slow aggregation test and separation experiment. The effects of VX-680 at different concentrations on the migration ability of HepG2 cells was detected by wound healing assay. The expression of E-cadherin in HepG2 cells was detected by Western blot. RESULTS:The results of the slow aggregation test showed that compared with the control group, the number of cell clumps formed in experimental groups was significantly decreased (P<0.01). The results of separation experiment showed that the ratio of N_TC/N_TE gradually decreased with the increased concentration of VX-680. The results of wound healing assay showed that as the concentration of VX-680 increased, the cell scratch healing ability gradually weakened compared with control group. The results of Western blot showed that the protein expression of E-cadherin in the HepG2 cells increased with the increased concentration of VX-680 (P<0.05). CONCLUSION:VX-680 increases the homogeneous adhesion and inhibits the migration of HepG2 cells.     

模型铲刀表面的法向压力及其土壤粘附

采用模型试验法，利用模型铲刀和小型压力传感器对模型铲刀表面的法向压力分布规律及土壤流动、粘附情况进行了试验研究，拟合出模型铲刀表面法向压力的回归方程。研究结果表明，法向压力在模型铲刀表面呈二次曲面分布，在模型铲刀的中部取得最大值。法向压力的变化引起土壤变形区域的含水量发生改变，导致土壤粘附主要发生在模型铲刀的上部和下部。     

轮式和履带式拖拉机适应性对比分析

拖拉机作为农业动力机械,其选型涉及到配套农具、耕作制度等诸多因素,本文以轮式拖拉机JD 4450,Zetor 16245和履带拖拉机ДT 75为例,对其结构性能、滚动阻力、附着性能、接地压力和适应性等方面在黑龙江垦区进行了对比分析,并对其选型提出了具体建议和要求。     

土壤粘附机理的化学吸附分析

在对已有土壤粘附机理进行综合分析的基础上，从结构化学和量子力学的统计效应出发，对参与粘附的各种因素———土壤表面性质、触土部件表面特性、土壤水中各种离子的性质进行了全面分析，从化学吸附角度，提出了以化学吸附为主的土壤粘附机理。该模型认为土壤与触土部件金属材料表面的粘附力是由土壤与金属表面间的化学吸附力（包括物理吸附力）、土壤水在金属与土壤之间形成的化学吸附力（宏观上表现为毛细管力）和水的粘滞阻力三部分组成