Evaluation of military helmets and roof padding on head injury potential from vertical impacts

Objective: Soldiers in military vehicles subjected to underbelly blasts can sustain traumatic head and neck injuries due to a head impact with the roof. The severity of head and neck trauma can be influenced by the amount of head clearance available to the occupant as well as factors such as wearing a military helmet or the presence of padding on the interior roof. The aim of the current study was to examine the interaction between a Hybrid III headform, the helmet system, and the interior roof of the vehicle under vertical loading.

Methods: Using a head impact machine and a Hybrid III headform, tests were conducted on a rigid steel plate in a number of different configurations and velocities to assess helmet shell and padding performance, to evaluate different vehicle roof padding materials, and to determine the relative injury mitigating contributions of both the helmet and the roof padding. The resultant translational head acceleration was measured and the head injury criterion (HIC) was calculated for each impact.

Results: For impacts with a helmeted headform hitting the steel plate only, which represented a common scenario in an underbelly blast event, velocities of ≤6 m/s resulted in HIC values below the FMVSS 201U threshold of 1,000, and a velocity of 7 m/s resulted in HIC values well over the threshold. Roof padding was found to reduce the peak translational head acceleration and the HIC, with rigid IMPAXX foams performing better than semirigid ethylene vinyl acetate (EVA) foam. However, the head injury potential was reduced considerably more by wearing a helmet than by the addition of roof padding.

Conclusions: The results of this study provide initial quantitative findings that provide a better understanding of helmet–roof interactions in vertical impacts and the contributions of the military helmet and roof padding to mitigating head injury potential. Findings from this study will be used to inform further testing with the future aim of developing a new minimum head clearance standard for occupants of light armored vehicles.     

鲤体内芳香烃受体的分离纯化及其与葸的相互作用

从暴露于污染物蒽的鲤肝脏中提取出芳香烃受体,并采用紫外可见分光光度计进行最大吸收波长扫描,再通过离子交换层析法分离纯化鲤体内的芳香烃受体,并采用聚丙烯酰胺凝胶电泳对受体进行鉴定,最后通过傅里叶变换红外光谱探讨芳香烃受体与蒽结合后的结构变化.结果表明,提取的芳香烃受体在280 nm处有特征吸收峰,测得质量浓度为27.3 mg/mL.通过离子交换层析法纯化了单一组分的受体蛋白质,其相对分子质量约为110 kD.测定了芳香烃受体的红外光谱,与蒽结合后其在一定波段的谱峰发生了明显位移,表明污染物配体蒽能与芳香烃受体结合,并对其蛋白二级结构产生明显影响.     

Colloid‐facilitated transport of metolachlor through intact soil columns

Abstract

This study evaluated the role of water dispersible colloids with diverse physicochemical and mineralogical characteristics in facilitating the transport of metolachlor through macropores of intact soil columns. The soil columns represented upper solum horizons of an Alfisol in the Bluegrass region of Kentucky. Three different colloid suspensions tagged with metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl)acetamide] were introduced at a constant flux into undisturbed soil columns. The eluents were collected and analyzed periodically for colloid and metolachlor concentrations. Colloid recovery in the eluents ranged from 54 to 90 %. The presence of colloids enhanced the transport of metolachlor by 22 to 70 % depending on the colloid type and mobility. Colloids with higher pH, organic carbon, cation exchange capacity (CEC), total exchangeable bases (TEB), surface area (SA), and electrophoretic mobility (EM), showed better mobility, greater affinity for interaction with the herbicide and, thus, greater potential to co‐transport metolachlor. In contrast, increased level of kaolinite, Fe, and Al inhibited metolachlor adsorption and transport. In spite of the increased transportability of metolachlor by the presence of soil colloids, the colloid bound herbicide portion accounted for a very small part of the observed increase. This suggests that surface site exclusion mechanisms and preferential sorption induced by the presence of colloids are more important than ion exchange phenomena in promoting herbicide mobility in subsurface environments.     

煤层底板隐伏陷落柱突水预测及采前注浆加固评价

华北型煤矿开采受底板岩溶强含水层威胁，通过对淮南张集矿1613A工作面底板隐伏岩溶陷落柱突水危险性分析，采用FLAC3D方法模拟采动条件下岩溶陷落柱活化过程。模拟结果显示:陷落柱上方的煤层底板岩体发生塑性变形，导致陷落柱附近岩体失稳，陷落柱筒壁产生局部剪切破坏，剪切破坏位置易导致奥灰强含水层发生陷落柱突水。采前采用注浆方法改造岩溶陷落柱，对改造后的陷落柱进行数值模拟分析，其内部注浆岩体对陷落柱筒壁具有良好的支撑作用，抑制了筒壁位置剪切破坏的发生，使有效隔水层厚度增大，降低了陷落柱突水的危险性。     

水泥厂清库作业必须用好安全绳

简述了水泥厂贮存生料和熟料的直筒库清库作业中常常发生人身伤害事故的原因,提出了预防事故的措施。     

辽河入海口及城市段柱状沉积物金属元素含量及分布特征

通过对辽河入海口地区(LN-2)和沈阳地区(LN-5)柱状沉积物粒度组成、TOC、TN、C/N比值和金属元素的分析,结合沉积物~(210)Pb的年代测定,探讨了有机质和金属元素的垂直变化特征及其影响因素,对沉积物有机质来源进行了初步分析,并采用地质累积指数法(I_(geo))和富集因子法(EFs)对沉积物中金属进行污染评价.研究表明,LN-2和LN-5均以粉砂为主,LN-2粒度组成和有机质含量垂向分布变化不大,LN-5则呈波动变化.通过C/N比值对沉积物有机质来源进行分析,结果显示LN-2中C/N比值范围在5.24~7.93之间,具有机质来源以河流自身为主,LN-5中C/N比值范围在9.94~14.21之间,以陆源输入为主.Al、Ca、Fe、Mn、Ni、Cu、Zn、Cd、Pb和Cr在两个柱状沉积物垂向上变化规律有所不同,LN-2沉积物中Ni和Zn元素以及LN-5沉积物中Pb和Zn元素受自然作用和人为因素共同影响,其他元素均与有机质分布规律相似,表明这些元素主要受自然作用和有机质影响.研究地区金属元素污染评价结果显示,Ni、Zn和Pb的污染程度较其他元素严重.结合辽宁省和研究地区近20年的经济发展情况,探讨了人类活动对环境的影响.     

Two-year measurements of surface ozone at Dangxiong, a remote highland site in the Tibetan Plateau

Measurements of surface O3 and carbon monoxide(CO) were made from September 2009 to August 2011 at Dangxiong(30.48°N, 91.10°E, 4187 m a.s.l.), a remote highland site in a southern valley of the Nyainqêntanglha Mountains in the Tibetan Plateau, China. The monthly mean O3 mixing ratio ranged from 29.1 to 51.4 ppb, with an average of 38.5 ppb, and the maximum value was observed in May. The average diurnal cycle of O3 concentration showed a minimum in early morning and a maximum in the afternoon, with a broader "high platform" from the late morning to the late afternoon, and resembled that of surface wind speed. The concentration of surface O3 was highly significantly correlated with tropospheric column O3 over the regions surrounding Dangxiong and with that of surface O3 observed at a site north of the Nyainqêntanglha Mountains, suggesting a good regional representativeness of surface O3 at Dangxiong. In the afternoon when stronger winds blew, surface air showed distinct features of free-atmospheric air, with higher O3, lower CO, and lower relative humidity(RH). The negative O3–CO and O3–RH correlations in most months indicate a significant influence of air masses from the free troposphere. Trajectory analysis suggests that air masses originating from the south of the site make a negative net contribution to surface O3 and a positive contribution to CO and humidity, and those from the northwest sector contribute conversely to the respective quantities.     

渭河陕西段潜流带沉积物重金属变化初步分析

为厘清潜流带沉积物重金属时空变化及与水量交换、沉积物颗粒结构间的关系,于2013年春夏两季对渭河陕西段5个研究断面66个测试点位沉积物的野外原位渗透系数、颗粒粒径、重金属含量进行分析.结果表明:影响渭河沉积物渗透系数的主要因素是沉积物粒径,同时沉积物垂向分层、排列组合也影响其渗透性能;沉积物重金属Cu、Zn、Pb、Cd质量分数在垂向上不同深度其含量大小不同,在时间上总体呈现春季夏季,富集系数(EF指数)分析结果显示春季Cu、Zn(除华县)、Pb(除眉县)、Cd富集严重且主要受人为输入源影响,夏季除Cd元素外,Cu、Zn、Pb的EF值均1.5,说明其含量主要来源于地壳和岩石圈的自然风化过程;Pearson相关分析发现粘土与粉砂(粒径0.075 mm)百分比与沉积物重金属质量分数呈弱相关,重金属粒径效应不显著,粒径不是控制重金属含量的主要环境影子;对单一重金属垂向不同深度含量进行相关性研究发现除Cd外,其余3种重金属在垂向上的相关系数均0.5(p0.01),说明单一重金属在垂向上具有同源性且存在相互迁移与转化.     

城市区域近地表灰尘及重金属沉降垂向季节变化

随着城市高层建筑的出现,人类日常生活的垂向空间范围逐渐向上延伸,近地表灰尘及重金属沉降垂向分布的季节特征值得关注.本研究分别在春、夏、秋、冬四季采集贵阳市某生活-文教区近地表不同空间高度平台上的灰尘样品,分析灰尘沉降通量及灰尘中Ca、Fe、Cd、Cr、Cu、Ni、Pb和Zn含量,探讨灰尘沉降通量及元素含量随空间高度的变化,揭示区域近地表灰尘及重金属沉降垂向分布的季节变化特征.结果表明,空间高度灰尘沉降通量季节变化总体上表现为冬季灰尘沉降通量最大,春季次之,夏季最低;冬季灰尘沉降通量沿垂向空间高度的分布差异最大,其次是夏季,春秋两季灰尘沉降通量垂向空间差异较小;季节变化对低层空间平台灰尘沉降通量影响大于高层空间;春季灰尘中元素含量最高,秋季灰尘重元素含量相对较低;元素含量随时空变化最大的是Zn,变化较小的是Ca.冬、春季节大气逆温层可能是灰尘沉降量和Pb、Zn等元素含量升高的原因之一.     

南京夏季城市冠层大气 CO2浓度时空分布规律的观测

城市是CO2重要排放源,直接观测城市中大气CO2浓度对于研究人类活动对大气温室气体的贡献至关重要,而在城市中多个站点、多个高度上观测大气CO2浓度则有助于认识城市CO2浓度的时空变化规律,确定其影响机制.本研究于2014年7月18日至7月25日在南京主城区东、西、南、北和中共5个方位(100 m左右高度),2014年8月3日至2014年8月9日在南京主城区中部站点的3个高度(30、65和110 m)观测CO2浓度.结果表明:1南京主城区垂直方向上CO2浓度存在明显梯度,近地面30 m处CO2浓度受人为活动影响明显,平均值达427.3×10-6(±18.2×10-6)(摩尔分数,下同),高层65m、110 m处CO2浓度混合均匀,平均值分别为411.8×10-6(±15.0×10-6)和410.9×10-6(±14.6×10-6).大气层结越稳定,CO2浓度越高,垂直梯度越大.2南京主城区CO2浓度的水平分布受风和大气稳定度的控制.观测期间盛行东北风向,导致CO2浓度分布整体呈现西南高,东北低的格局,城市主城区上下风向CO2浓度差为7.8×10-6.而且水平风速越大,越有助于将上风向的CO2传输至城市的下风向,CO2浓度差就越小.大气层结越稳定,整体CO2浓度越高.3南京主城区5个站点CO2浓度均有明显的日变化,日最高值出现在交通早高峰期间,谷值在17:00左右,在19:00左右有时会因交通晚高峰而出现次高值.