基于行人碰撞事故重建的颅脑损伤准则效能研究

为了深入研究不同颅脑损伤准则对道路交通事故中行人颅脑损伤的预测与评价性能,从已有的交通事故调查数据库中选出可以用于进行事故虚拟重建且具有详细人体颅脑伤情记录的10例行人车辆碰撞事故案例,采用多刚体动力学和有限元分析方法,对事故中人和车辆运动学响应及行人颅脑损伤情况进行虚拟重建,在此基础上,采用LASSO回归分析方法分析了多个基于人体头部运动学响应的颅脑损伤准则与事故中行人颅脑损伤的相关性;借助文献中的损伤风险曲线,分析了不同基于脑组织应变的损伤准则与行人典型颅脑损伤（弥散性轴索损伤和脑挫伤）之间的关系。研究结果表明：在多个基于人体头部运动学响应的颅脑损伤评价准则中,同时考虑头部线性和旋转运动,且体现头部碰撞功率的头部碰撞能量（HIP）准则能最有效地评价真实的颅脑损伤;基于脑组织应变的颅脑损伤准则中,累计应变损伤测量（CSDM）准则相对于最大主应变（MPS）准则能更有效地评价典型弥散性脑损伤（DAI）,而扩张损伤测量（DDM）准则所反映的脑挫伤程度远低于真实的损伤状况,所以该准则难以准确预测脑挫伤的损伤风险。     

Ports in Proximity – Competition and Coordination among Adjacent Seaports,edited by Theo Notteboom,Cesar Ducruet,and Peter de Langen

The summer minimum extent of Arctic sea ice shrank drastically in these years, and the opportunity on Arctic international shipping emerged. The Northern Sea Route (NSR), formerly blocked by permanent ice, was completely ice-free in September in the past 3 years. Because this route is much shorter than conventional Asia–Europe shipping lane, many maritime countries have paid attention to exploit the enormous potential of the Arctic Ocean from economical consideration. This study measured the economical advantage of the seasonal NSR by calculating the shipping cost saved.     

弥漫性轴索损伤后内质网钙释放对轴突内早期钙离子浓度的影响

目的研究弥漫性轴索损伤(diffuse axonal injury,DAI)后内质网(endoplasmic reticulum,ER)钙释放的变化,以及对轴突内早期钙离子浓度的影响,并探讨造成ER钙释放的可能分子机制。方法使用体外培养7¹2d的小鼠神经元行轴突牵拉损伤建立体外DAI模型,根据是否行牵拉损伤分为损伤组及对照组。使用ER Tracker Red标记ER,观察ER在轴突损伤前后的分布。通过Fluo-4AM钙探针及激光共聚焦钙成像技术测量单个轴突内钙离子浓度的变化,并使用20mmol/L咖啡因作用于细胞,使ER内钙离子快速排空,测量轴突部位咖啡因作用前后的钙离子浓度变化,从而间接观察ER内钙存量的变化。结果 ER Tracker Red荧光结果显示ER存在于神经元轴突部位中,损伤后的轴突肿胀部位存在ER聚集的现象。神经元牵拉损伤后,被牵拉的轴突钙离子浓度明显升高,与对照组比较,差异有统计学意义(P<0.05),受损的轴突表现出肿胀及"串珠样"变性等病理学改变。除损伤后2min外,使用无钙细胞外液虽然明显降低了牵拉损伤导致的轴突的钙离子浓度升高,但在212d的小鼠神经元行轴突牵拉损伤建立体外DAI模型,根据是否行牵拉损伤分为损伤组及对照组。使用ER Tracker Red标记ER,观察ER在轴突损伤前后的分布。通过Fluo-4AM钙探针及激光共聚焦钙成像技术测量单个轴突内钙离子浓度的变化,并使用20mmol/L咖啡因作用于细胞,使ER内钙离子快速排空,测量轴突部位咖啡因作用前后的钙离子浓度变化,从而间接观察ER内钙存量的变化。结果 ER Tracker Red荧光结果显示ER存在于神经元轴突部位中,损伤后的轴突肿胀部位存在ER聚集的现象。神经元牵拉损伤后,被牵拉的轴突钙离子浓度明显升高,与对照组比较,差异有统计学意义(P<0.05),受损的轴突表现出肿胀及"串珠样"变性等病理学改变。除损伤后2min外,使用无钙细胞外液虽然明显降低了牵拉损伤导致的轴突的钙离子浓度升高,但在2³0min时间段中钙离子浓度升高依然存在,与对照组比较,差异有统计学意义(P<0.05)。对照组中未经牵拉损伤的神经元轴突可被20mmol/L咖啡因激起一个明显的轴突钙离子浓度升高,而牵拉损伤后的轴突对咖啡因的这种钙升高反应程度明显下降,与对照组比较,差异有统计学意义(P<0.05)。结论 DAI后的轴突钙离子浓度升高不仅由细胞外钙内流引起,细胞内钙释放同样参与其中。ER是引起这种DAI后轴突内钙释放的细胞器来源。     

综合考虑高温后RC柱失效路径的可靠性分析

引入高温后混凝土和钢筋强度折减系数,建立4面受火后偏心受压柱的抗力模型和极限状态方程,利用蒙特卡罗法对高温后钢筋混凝土偏压柱综合考虑失效路径下的可靠性进行了数值模拟分析.综合考虑了单一失效路径和2种失效路径下受火后偏压柱的可靠性.结果表明,随着受火时间的增加,柱的可靠性指标逐渐变小;偏心距较小时,考虑2种失效路径下对受火后柱进行可靠性评估是不安全的;在偏心距较大时,考虑单一失效路径对受火后柱进行可靠性评估是不安全的,所以综合考虑高温后RC柱失效路径的可靠性比只考虑单一因素更符合真实情况.     

Protective effect of glutamine pretreatment on ischemia-reperfusion injury of spinal cord in rabbits

Objective To investigate the effect of glutamine (Gln) on the content of reduced glutathione hormone (GSH) and aminoglutaminic acid (Glu) of spinal cord following ischemia-reperfusion injury. Methods Totally 40 healthy adult male rabbits were randomly divided into five groups: sham-operation group (S group), ischemia-reperfusion injury group (I/R group), low-dose glutamine group (L Gln group), median-dose glutamine group (M Gln group) and high-dose glutamine group (H Gln group). After glutamine preconditioning, the model of spinal cord ischemia-reporfasion injury was established according to Zivin's method. The general status of animals was observed and the changes of Jacobs scoring were recorded in each group. Malondialdehydes (MDA), GSH, Glu and superoxide dismutase (SOD) activity in lumbar spinal cord tissues were determined using chemical colorimetry. The neuron number and deviation rate in spinal cord anterior horn were observed histopathologically. Results There was no significant difference between L Gin group and I/R group in behavior scoring, SOD activity, content of MDA and Glu, neuron number and deviation rate of spinal cord (P>0.05); however, there was a significant difference in GSH content of spinal cord (P<0.05). M Gln group and I/R group differed significantly (P<0.05) in behavior scoring, SOD activity, content of MDA, Glu, GSH, neuron number and deviation rate of spinal cord. Between H Gln group and M Gln group, there was no significant difference in behavior scoring, content of MDA and Glu, SOD activity, neuron number and aberration rate in spinal cord (P>0.05), whereas there was a significant difference in SOD activity and Giu content (P<0.05). Conclusion Pretreatment with medium-dose glutamine has a protective effect on spinal cord ischemia-reporfasion injury in rabbits, which may be related to the maintenance of GSH content, increase of SOD activity and reduction of MDA.     

Effect of ulinastatin on hepatic ischemia-reperfusion injury in rats

Objective To investigate the effect of ulinastatin (UTI) on hepatic ischemia-reperfusion injury in rats. Methods Totally 24 adult Sprague-Dawley rats were randomly divided into 3 groups: sham-operated control group (SO group), ischemia-reperfusion group (I/R group) and ulinastatin group (UTI group). Liver in I/R group underwent 1 h of reperfasion after 30 min of ischemia. In UTI group, UTI (2×104 U/kg) was administered to rats 30 min before modeling. The levels of alanine aminotransferase, aspartate aminotransferase and tumor necrosis factor-alpha (TNF-α) in serum were measured and the levels of nitric oxide and malondialdehyde in liver were determined. The histological changes of liver were observed. Results The levels of alanine aminotransferase, aspartate aminotransferase and TNF-α in serum were significantly increased in I/R group compared with those in UTI group (P<0.05). The levels of nitric oxide and malondialdehyde in liver were significantly higher in I/R group than in UTI group (P<0.05).Histological examination of liver indicated that the damages were more severe in I/R group than in UTI group.Conclusion UTI has the ability to inhibit the production of TNF-α and oxyradical, and ameliorate microcirculatory dysfunction in rats with hepatic ischemia-reperfasion injury.     

“易”轮CO2间火灾事故的分析与思考

文章通过对＂易＂轮CO2间火灾事故的分析,提醒广大船员在日常工作和生活中必须遵守船舶防火安全规定,增强防火意识,将船舶火灾预防工作真正落实到实际行动上。     

SBS改性沥青粘结防水层的作用和施工控制

通过作者在高速公路大中修的实践,分析SBS改性沥青粘结防水层在预防水损坏起到的作用和施工过程的控制.     

自动驾驶中座椅旋转速度对乘员的影响

为提高自动驾驶车辆的安全性,提出用一种旋转速度曲线把座椅旋转至指定角度,研究此旋转速度下的乘员生物力学响应.首先,根据所建立的碰撞模型与假人试验数据进行对比验证;其次,改变座椅旋转方向和速度研究乘员旋转至指定位置乘员的生物力学响应.结果表明:在200 ms内采用等腰梯形旋转速度曲线旋转至±45°和±90°不会引起乘员额...     

考虑潜在类别的老年行人交通事故严重程度致因分析

人口老龄化问题日益突出，老年行人的出行安全同样引起各界重视。本文基于潜在类别聚类分析和随机参数Logit模型相结合的两步法深入探究影响老年行人交通事故严重程度的诱因。对北卡罗来纳州2007—2019年65岁及以上老年行人与机动车的碰撞数据进行清洗。为消除碰撞数据中固有的未观察到的异质性，首先进行潜在类别聚类分析，依据拟合优度指标确定最佳聚类数，将数据分成3个集群，分别对每个集群进行特征描述。然后，分别对每个集群建立随机参数Logit模型，以进一步探索集群内部未观察到的异质性，同时计算各显著变量的边际效应，量化其对事故严重程度概率的影响。结果显示，随机参数Logit模型具有更好的拟合优度；不同集群参数估计结果有所差异，一些变量只在特定集群内是显著的；集群1中，“救护车援助”为随机变量，集群2中“事故发生在城市”为随机变量，集群3中未发现随机变量，退化为多项Logit模型。本文研究结果可为交通工程师和政策制定者提供更可靠准确的老年行人交通事故严重程度诱因信息，为老年行人出行安全改善方案的制定提供理论支撑和技术支持。