围生期双酚A暴露对子代大鼠脾脏免疫功能的影响

为了研究围生期双酚A(BPA)暴露对子代脾脏免疫功能的影响,选择F344大鼠,按体重随机分为对照、低、中、高4个剂量组(BPA暴露剂量分别为0、4、40、400mg·kg-1·d-1),从雌鼠妊娠第0天开始至子鼠出生后30天,每天灌胃染毒1次,观察子鼠脾脏组织形态学的变化,并采用实时定量PCR检测IL-2、IL-12、IFN-γ、TNF-α4种细胞因子mRNA表达的改变.结果表明,1)与对照组相比,低剂量组子鼠脾重、脾脏指数均显著增加(p<0.05),体重无显著变化(p>0.05);中剂量组子鼠脾脏指数显著增加(p<0.05),体重和脾重无显著变化(p>0.05);高剂量组子鼠体重、脾重均显著降低(p<0.05),脾脏指数无显著变化(p>0.05).2)与对照组相比,各暴露组子鼠脾脏IL-2、IL-12、IFN-γ、TNF-α4种细胞因子mRNA表达均显著降低(p<0.01).以上结果提示,BPA可能能够透过胎盘屏障并通过乳汁传递给子代,降低子代的机体免疫功能.     

Inclusion of phone use while driving data in predicting distraction-affected crashes

Introduction: Given the tremendous number of lives lost or injured, distracted driving is an important safety area to study. With the widespread use of cellphones, phone use while driving has become the most common distracted driving behavior. Although researchers have developed safety performance functions (SPFs) for various crash types, SPFs for distraction-affected crashes are rarely studied in the literature. One possible reason is the lack of critical distracted behavior information in the commonly used safety data (i.e., roadway inventory, traffic, and crash counts). Recently, the frequency of phone use while driving (referred to as phone use data) is recorded by mobile application companies and has become available to safety researchers. The primary objective of this study is to examine if phone use data can potentially predict distracted-affected crashes. Method: The authors first integrated phone use data with roadway inventory, traffic, and crash data in Texas. Then, the Random Forest (RF) algorithm was applied to assess the significance of the feature - phone use while driving - for predicting the number of distraction-affected crashes on a road segment. Further, this study developed two SPFs for distraction-affected crashes with and without the phone use data, separately. Both SPFs were assessed in terms of model fitting and prediction performances. Results: RF results rank the frequency of phone use as an important factor contributing to the number of distraction-affected crashes. Performance evaluations indicated that the inclusion of phone use data in the SPFs consistently improved both fitting and prediction abilities to predict distracted-affected crashes. Practical Applications: The phone use data provide new insights into the safety analyses of distraction-affected crashes, which cannot be achieved by only using the conventional roadway inventory and crash data. Therefore, safety researchers and practitioners are encouraged to incorporate the emerging data sources in reducing distraction-affected crashes.     

环境监测在环境影响评价中的影响分析

环境监测贯穿于整个环境影响评价体系中,环境影响评价中的评价初期、建设期、运行期以及后评价期,均由环境监测数据来支撑结果,是环境影响评价的技术基础,同时具有较强的监督功能。     

阜新市生态地质环境质量模糊综合评价

生态地质环境质量评价,实为生态地质环境的适宜性评价。本文以地貌类型、森林覆盖率、人口密度等16个指标为主要影响因子,确定了生态地质环境质量评价指标的单因素评价模型和评价指标体系。采用模糊数学方法,对阜新市生态地质环境质量进行了综合评价。结果表明阜新地区生态地质环境质量总体良好。经验证,定量评价与定性评价结果较吻合,证明该套基于模糊综合评判技术的生态地质环境质量的定量评价是切实可行的．结论是可信的。     

深部孤岛工作面区段煤柱冲击地压的试验研究

以冲击启动理论为基础,结合覆岩空间结构思想,采用相似模拟试验方法,研究了孤岛工作面上覆岩层空间结构特点及采动围岩应力场的分布、变化规律,进一步探讨了孤岛工作面区段煤柱冲击地压发生机理。结果表明,两侧充分开采的孤岛工作面上覆岩层呈"C"型覆岩空间结构,工作面承受上部岩层及两侧采空区上覆岩层转移过来的部分岩层重量,在工作面两侧形成应力集中区域,导致采动围岩应力场达到极限平衡状态,该集中应力可视为采动围岩近场极限平衡系统的静载荷。孤岛工作面开采过程中"C"型覆岩空间结构逐渐演化形成"W"型空间结构,极限平衡系统静载荷发生转移和改变,最终由上下区段煤柱全部承担上覆岩层重量,系统载荷增至最大,处于临界失稳状态。"W"型覆岩空间结构大面积失稳,为系统提供了外动载荷,系统在动载荷的扰动下突破平衡极限,从而发生区段煤柱冲击。最后,基于孤岛工作面应力分布规律确定了区段煤柱的合理尺寸。     

基于城市面板数据的PM2.5对公共健康的影响

基于Grossman健康生产函数,利用2008~2017年全国280个城市的面板数据,以PM_2.5为空气污染的代表指标,探讨中国空气污染与公共健康之间的动态关系,考虑到公共健康的空间效应,采用空间计量模型进行实证研究.结果表明,在未考虑空间效应的情况下,PM_2.5浓度每增加1%,城市总人口死亡率增加0.040%;考虑空间效应后,PM_2.5浓度每增加1%,城市总人口死亡率增加0.0606%.PM_2.5污染对公共健康具有显著的负面影响,由于存在空间溢出效应,PM_2.5污染对城市公共健康水平的影响程度增加,表明忽视空间相关性的存在,会低估PM_2.5污染对公众健康的影响;而经济发展水平的提高以及产业结构的调整对公共健康有较强的改善作用.     

雾霾污染的空间外溢与治理政策的检验分析

以2006~2016年城市层面数据为样本,结合空间扩散效应深入探究雾霾污染的影响机理,并对已出台治霾政策的治理效果和传导机制进行识别.研究发现：考察期内我国雾霾污染具有一定时滞性、空间相关性和时空“警示作用”;以往环境规制由于诱发污染产业地区间就近转移对减霾贡献并未达到预期效果.“大气十条”的治霾效果明显,到2016年该政策的实施使重点关注的三大经济带PM_2.5显著降低约7.1%,其中,中部和东部区域政策实施城市治理效果最为显著;政策实施以来各地区环保部门通过对重污染企业的限产整治取得了降霾的短期治理效果,但对重污染企业的创新激励传导作用并不显著.因此,未来雾霾治理政策更需注重如何通过激发企业绿色技术创新从而建立根治雾霾污染的长效机制.     

Environmental impact and health risk assessment of volatile organic compound emissions during different seasons in Beijing

Volatile organic compounds (VOCs) are major contributors to air pollution. Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer from 21 July to 25 August 2016 in Beijing, the environmental impact and health risk of VOC were assessed. In the winter polluted days, the secondary organic aerosol formation potential (SOAP) of VOC (199.70 ± 15.05 μg/m³) was significantly higher than that on other days. And aromatics were the primary contributor (98.03%) to the SOAP during the observation period. Additionally, the result of the ozone formation potential (OFP) showed that ethylene contributed the most to OFP in winter (26.00% and 27.64% on the normal and polluted days). In summer, however, acetaldehyde was the primary contributor to OFP (22.00% and 21.61% on the normal and polluted days). Simultaneously, study showed that hazard ratios and lifetime cancer risk values of acrolein, chloroform, benzene, 1,2-dichloroethane, acetaldehyde and 1,3-butadiene exceeded the thresholds established by USEPA, thereby presenting a health risk to the residents. Besides, the ratio of toluene-to-benzene indicated that vehicle exhausts were the main source of VOC pollution in Beijing. The ratio of m-/p-xylene-to-ethylbenzene demonstrated that there were more prominent atmospheric photochemical reactions in summer than that in winter. Finally, according to the potential source contribution function (PSCF) results, compared with local pollution sources, the spread of pollution from long-distance VOCs had a greater impact on Beijing.     

基于“三生空间”的土地利用功能转型及生态服务价值研究——以福州新区为例

分析土地利用功能转型及带来的生态服务价值转变,是快速城镇化地区土地资源开发利用和“三生空间”管控的重要依据。论文基于福州新区2000、2009和2015年3期Landsat ETM+/OLI遥感数据和“三生”土地利用主导功能分类体系,应用GIS定量研究了福州新区15 a土地利用功能转型特征及生态系统服务价值时空演变,结果表明： 1）15 a间福州新区的生活生产空间增长迅速,面积增加了11 224.63 hm²,增长率达82.31%;生态生产空间面积出现先下降后增长趋势,总体增长了19.94%;生活生产空间的增长源于对生态空间和生产生态空间的侵占,生态生产空间的增长源于对湿地、海域等生态空间的侵占。2）15 a间福州新区生态系统服务价值下降了21.69%,其中生态空间下降总量最大,减少了6.822 8亿元,生活生产空间下降幅度最大,下降了92.10%。3）区域生态系统服务价值存在提高和下降两种相反趋势,导致研究区生态系统服务价值降低的主要原因是生活生产空间对生态空间和生产生态空间的侵占,贡献率分别达38.60%和18.77%,其次为生态生产空间对生态空间的侵占。4）推进福州新区“三生空间”协同布局,应加强区内生态林地、闽江河口、海岸线等重点生态空间的保护,稳步推进新区核心区域生活空间基础设施优化,集约利用生产空间,增加产出效益。     

直升机主减反共振隔振系统中附加阻尼器的影响分析

目的分析阻尼参数对共振峰抑制与反共振隔振有效频率范围的影响。方法在主减共振梁上安装阻尼器,改变阻尼大小进行仿真分析。结果随着阻尼系数的增大,共振峰值逐渐降低,反共振点频率基本不变,隔振效率有所下降,有效隔振效率范围有所拓宽。建议把阻尼大小设为0.01最为有效。结论通过安装阻尼器并改变阻尼大小可以有效地调节减震效率及反共振隔振有效频率范围。