硝基苯类化合物在铜电极上的电还原特性和还原机理

采用循环伏安法,对硝基苯类化合物在铜电极表面上的电还原特性进行了研究,评价了它们在铜电极上的电还原反应活性,分析了此类化合物在铜电极上的还原机理,并且讨论了电还原反应活性和此类化合物结构之间的关系．结果表明,硝基苯类化合物在铜电极表面有还原电位,也就是说,能在铜电极表面被直接还原．     

2009年姚安6.0级地震强震动应急观测的数据处理及其震害启示

对2009年7月9日云南姚安6.0级地震应急流动观测获取的强余震记录进行了处理和分析,包括记录的滤波及零漂处理,5.2级、4.7级、4.6级三次强余震的PGA、PGV、PGD及PSV、PSD以及对应的谱烈度(St)与相对持时(Td)等的计算及其分析.结果表明:这些强余震近场记录的滤波处理对高频成份影响较大,对低频部分影...     

足尺钢桁架连梁恢复力模型试验研究

对4个足尺的钢桁架连梁模型进行了低周反复荷载试验,研究了结构的破坏形态、滞回性能。利用试验数据进行回归分析,建立了骨架曲线恢复力模型;对滞回曲线进行了分析,研究了连梁的刚度退化规律,建立了循环荷载作用下结构的恢复力模型。模型和试验曲线较为吻合,可用于结构的弹塑性分析。     

Using retro-reflective cloth to enhance drivers’ judgment of pedestrian walking direction at night-time

Purpose: Fatal pedestrian collisions are over-represented at night and poor conspicuity is believed to be a leading causative factor. Retro-reflective clothing enhances pedestrian conspicuity, particularly when placed in a biological motion or “biomotion” configuration. In this study, we explored how various retro-reflective clothing configurations affected the ability to judge the direction of a pedestrian walking across the road, which has important implications for collision avoidance. Methods: Participants included 21 young drivers (mean age 21.6 ± 2.0 years) with normal vision. A closed-road circuit was used to assess the accuracy of drivers’ judgement of the direction of walking of a pedestrian at night-time wearing one of five different clothing configurations: four with retro-reflective materials placed in different locations (Biomotion, Legs + Torso, Torso Only, Legs Only), and a control wearing only black clothing (Street). Participants were seated in a stationary vehicle with low beam headlamps, 135 m from a pedestrian, who walked across the road from both sides, in different directions (towards the car, straight across the road, or away from the car). Outcome measures included drivers’ response accuracy and confidence ratings for judging pedestrian walking direction. Results: Accuracy in judging pedestrian walking direction differed significantly across the clothing configurations (p < 0.001). Response accuracy was significantly higher for the Biomotion configuration (80% correct), compared to the other retro-reflective (Legs + Torso 64%; Torso Only 53%; Legs Only 50%) and Street configurations (33%). Similar trends were noted for confidence ratings across the clothing conditions, yet the relationship between confidence ratings and response accuracy within each clothing configurations was poor. Conclusions: The use of retro-reflective clothing in a biomotion configuration facilitated the highest accuracy and confidence in drivers’ judgment of pedestrian walking direction, compared to other configurations. These findings highlight the importance of using biomotion clothing for pedestrians at night, to not only facilitate drivers’ earlier recognition of pedestrians, but also increase their accuracy in determining the walking direction of pedestrians as they cross the road. Practical applications: The use of clothing incorporating retro-reflective material in a biomotion configuration for pedestrians crossing roads at night provides enhanced cues for drivers regarding the presence and walking direction of pedestrians.     

光催化反应器中臭氧产量及其影响因素研究

二氧化钛光催化降解染料废水具有反应迅速、降解彻底的优点.文章以悬浮态TiO2作为自制紫外光催化反应器(145W,185W)的催化剂,处理通有定量夺气的清水来产生微量的臭氧,通过改变臭氧捕捉方式、初始pH值、反应时间、TiO2用量及光照强度,研究纯水中臭氧产量及pH与上述因素之间的关系,并以循环伏安法作为对照.单因素实验...     

排水循环灌溉下稻田磷素时空分布特征

排水循环灌溉具有提高降水资源利用率和减少农田面源污染的潜力,为缓解我国南方地区降雨分布与水稻作物需水时间不匹配和农田磷流失污染的问题,开展了排水循环灌溉条件下稻田磷素时空分布规律研究.采用田间试验的方法,监测藕塘水和鱼塘水循环灌溉下水稻田面水和渗漏水中总磷、可溶性磷和可溶性反应磷的质量浓度,及土壤剖面总磷与Olsen-P含量的变化.结果表明,排水循环灌溉下水稻田面水和渗漏水中不同形态磷素质量浓度沿程降低,尤其渗漏水磷质量浓度的减少趋势更为显著,排水循环灌溉水源中磷质量浓度在一定范围内的变化不会增加田面水和渗漏水中的磷质量浓度.田面水和渗漏水中不同形态磷质量浓度在不同灌溉时期的变化较大,8月田面水和渗漏水的磷质量浓度明显低于其它时期.表土Olsen-P含量随距进水口的距离的增加而减少,并随排水循环灌溉水中磷质量浓度的增加而增加;土壤剖面TP含量受排水循环灌溉的影响不明显.在8月水稻需肥高峰期进行排水循环灌溉或延长灌溉水的流程,可明显改善排水循环灌溉下稻田的磷素去除效率.     

钢铁行业循环经济与清洁生产技术评价方法研究

在分析钢铁行业循环经济与清洁生产技术范围与特点的基础上,通过循环经济3R原则、清洁生产技术评价的方法调研并结合生命周期理论,建立了钢铁行业循环经济与清洁生产技术的分析评价方法模型,并采用德尔菲方法进行专家多轮讨论修正,完善了模型的评价体系,为我国钢铁行业推行循环经济与清洁生产技术提供理论和技术支持。     

环甲基硅氧烷的环境分布、行为与效应研究进展

近年来,挥发性环甲基硅氧烷(cVMS)在生产和生活过程中的广泛使用导致其环境和人体暴露风险日益增加,由于其具有持久性、潜在的生物积累性和毒性而被受关注。目前,人们对cVMS在全球各种环境介质中的赋存、行为及效应有一定的了解。排入环境中的cVMS大部分进入大气,在水体、沉积物、土壤和生物体中也有一定的含量。研究表明,希腊室内空气降尘中总的环硅氧烷含量中位数最高(1 380 ng·g~(-1)),其次为中国(362 ng·g~(-1));中国污水处理厂总的硅氧烷年人均通量(10 g·y~(-1))低于英国(D4~D6 48.3 g·y~(-1))和美国(D4~D6 93.5 g·y~(-1)),其中大连市一家采用CWSBR工艺的污水处理厂进水中cVMS的总浓度(1.05μg·L~(-1))普遍低于希腊(5.14μg·L~(-1))、西班牙(9.2μg·L~(-1))、加拿大(44μg·L~(-1))和一些北欧国家(17μg·L~(-1));我国大部分废水处理厂污泥中甲基硅氧烷的含量(0.1~lμg·g~(-1)dw)比一些北欧国家(26μg·g~(-1)dw)、希腊(20μg·g~(-1)dw)和加拿大(64μg·g~(-1)dw)等要低得多。中国普通居民吸入+摄食D4~D6的PELs中位数(173 ng·d~(-1))远低于中国普通人群的皮肤暴露(中位数18.5μg·d~(-1)),更低于英国成人日暴露量(1.875 mg·d~(-1))和美国妇女对总硅氧烷的日暴露量(307 mg·d~(-1))。环境中cVMS的行为和效应取决于其理化性质和具体的环境条件。进入大气的cVMS会与·NO_3、O_3和·OH反应,而与·OH反应脱去甲基生成硅醇是其主要的消除机制。污水处理过程中,大部分cVMS被污泥吸附固定,D6吸附污泥的能力最强,其次为D5和D4。挥发、吸附和非生物降解是cVMS在土壤中主要的环境行为。D4和D5可能存在生物放大作用。评估cVMS的TMF(trophic magnification factor)研究结果相互矛盾,且与BCF、BMF和BSAF的评估结果相反。总之,国内外对污水处理过程中cVMS的赋存状态和迁移、转化行为的研究比较多,且以进、出水和剩余污泥为主,而对整个工艺流程中具体变化的细化研究很少,对其生物积累特征、降解机制和降解产物更缺乏深入研究。因此,今后需要补充对其他环境介质、尤其是和人们居住、工作密切相关环境中cVMS分布规律的研究,深入探索其在实际环境中的降解过程,包括其降解产物或中间产物的环境行为,进一步评估其生态环境效应和人类健康风险。     

Effects of climate and exurban development on nest predation and predator presence in the southern Appalachian Mountains (USA)

In the eastern United States, land-use and climate change have likely contributed to declines in the abundance of Neotropical migrant birds that occupy forest interiors, but the mechanisms are not well understood. We conducted a nest-predation experiment in southern Appalachian Mountain forests (North Carolina, U.S.A.) during the 2009 and 2010 breeding seasons to determine the effects of exurban development and temperature on predator presence and the average number of days until eggs in an artificial nest were disturbed by predators. We baited artificial nests with quail (Excalfactoria chinensi) eggs and monitored them for 18 days. We used clay eggs, track plates, and motion-triggered cameras to detect and identify nest predators. The average number of days a nest was undisturbed decreased as mean temperature increased and, to a lesser extent, as the density of buildings increased. Nests on the ground were more often depredated than those in trees, likely due to increased predation by opossum (Didelphis virginiana) and other carnivores. Raccoons (Procyon lotor), opossums, corvids (Corvus brachyrhynchos and Cyanocitta cristata), chipmunks (Tamias striatus), black bears (Ursus americanus), and domestic cats (Felis catus) were the most commonly detected predators. Presence of these predators did not vary as a function of mean temperature. Domestic cats and corvids were detected more frequently in plots with high rather than low densities of buildings. Forest-interior specialists and Neotropical migrants often nest in cool, high-elevation areas with low housing density. These bird species, especially those that nest on the ground, may be most vulnerable to increased nest predation if temperature and exurban development increase at higher elevations as anticipated.     

带乘员及约束系统汽车正面碰撞的有限元法仿真研究

采用计算机模拟的方法,对国产某轿车发生正面碰撞时,乘员在佩带三点式安全带的约束状态下的运动响应进行研究,从乘员的运动响应情况、乘员舱的变形情况、假人的HIC值等几个方面分析了该车型的乘员保护安全性能.模拟结果表明,该车达到了安全法规的要求.并探讨了运用有限元法对带乘员及约束系统的整车正面碰撞的计算机模拟方法.