ASMs模型中异养菌减衰系数之间的关系及其测定

国际水协(IAWQ)推出的ASM1、ASM2、ASM2D号模型中描述微生物的衰亡过程采用了死亡-再生模式,而ASM3号模型中描述微生物的衰亡则采用了传统减衰模式,文章从两种减衰模式的机理出发,指出了两者之间的区别与联系,并详细推导了两种减衰模式中各参数之间的关系,以此得出了异养菌传统减衰系数bH'和死亡-再生减衰系数bH的测定计算方法。文中在20℃条件下,对以印染废水为主的实际污水处理厂活性污泥的异养菌减衰系数bH'和bH进行了测定,所得结果分别为0.20和0.50。     

Prenatal diagnosis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency in a family with a previous fatal case of sudden unexpected death in childhood

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a potentially fatal inherited disease with a carrier frequency of approximately 1:100 in most Caucasian populations. The disease is implicated in sudden unexpected death in childhood. A prevalent disease-causing point mutation (A985G) in the MCAD gene has been characterized, thus rendering diagnosis easy in the majority of cases. Since the clinical spectrum of MCAD deficiency ranges from death in the first days of life to an asymptomatic life, there are probably other genetic factors—in addition to MCAD mutations—involved in the expression of the disease. Thus, families who have experienced the death of a child from MCAD deficiency might have an increased risk of a seriously affected subsequent child. In such a family we have therefore performed a prenatal diagnosis on a chorionic villus sample by a highly specific and sensitive polymerase chain reaction (PCR) assay for the G985 mutation. The analysis was positive and resulted in abortion. We verified the diagnosis by direct analysis on blood spots and other tissue material from the aborted fetus and from family members.     

Effects of mid-trimester induced abortion on the subsequent pregnancy

The outcome of the pregnancy following (a) a mid-trimester termination of pregnancy (TOP) for fetal neural tube defect (NTD) (77 women=group 1); (b) mid-trimester TOP for fetal Down's syndrome (13 women=group 2); (c) delivery of a baby with NTD (119 women=group 3) was studied. The prenatal fetal loss was relatively high in all groups. In group 1 it was similar to that found in other studies after first trimester TOP, in group 2 it was associated with advanced maternal age and the unexpected finding in group 3 was not attributable to advanced maternal age. It is suggested that a previous NTD per se might increase the risk of fetal loss in the next pregnancy. A previous mid-trimester TOP for NTD was not associated with an increase in premature labour, small for dates babies or congenital abnormality in the next pregnancy, but there was a slight increase in the number of babies weighing less than 2500 g.     

内蒙古癌死亡率与土壤环境中化学元素的关系

利用中国癌死亡率与土壤环境中化学元素的相关性研究成果，研究了内蒙古癌死亡率与土壤环境中化学元素：As、Cd、Co、Cu、Hg、Mn、Ni、Pb、Se、V、Li、Na、K、Rb、Cs、Mg、Ca、Sr、Ba、B、Al、Ga、In、Tl、Sc、Y、La、Ce、Pr、Nd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Th、U、Sn、Ti、Zr、Hf、Sb、Bi、Ta、Te、Mo、W、Br、I、Fe等52个元素含量的关系。     

TNT当量法预测某石化设备爆炸后果评价

以烃化反应器为模拟发生泄漏事故源,泄漏的物料形成爆炸性气体,发生爆炸事故,采用TNT当量法预测爆炸事故后果,通过公式,计算出因爆炸冲击波导致肺出血而引起死亡的概率为0.5的半径.     

NO参与铝诱导蚕豆保卫细胞死亡的调控

铝(Al)是地壳中含量最丰富的金属元素,是酸性土壤中导致植物生长抑制和作物产量下降的一个主要因素,但铝毒性作用机制尚不清楚.本文以蚕豆叶表皮为材料,研究铝胁迫对气孔保卫细胞活性的影响,探讨NO在铝诱导细胞死亡中的作用.结果表明,一定浓度的A1Cl3可诱导气孔保卫细胞活性降低,部分细胞死亡,且随着铝浓度的增高细胞死亡率增高.死细胞呈现核固缩、核崩解、凋亡小体等典型凋亡特征,且凋亡抑制剂Z-Asp-CH2-DCB能阻止AlCl3诱发的细胞死亡.用NO清除剂c-PTIO、NO合酶抑制剂L-NAME或硝酸还原酶抑制剂NaN3降低铝处理组胞内NO后,细胞死亡率显著降低,胞内ROS、Ca2+水平同期降低;NaN3还能降低铝处理组中具有程序性死亡特征的细胞比率.用ROS清除剂AsA清除铝处理组胞内ROS后,细胞死亡率显著降低,胞内Ca2+和NO水平亦显著降低;铝处理液中加入Ca2+通道抑制剂LaCl3后,细胞死亡率低于铝单独处理组,胞内ROS和NO水平无明显改变.研究结果表明,铝胁迫引起的胞内NO合成增加通过Ca2+信号途径介导了保卫细胞的程序性死亡.     

The use of technology to address patterns of risk among teenage drivers

INTRODUCTION: The crash risk of teens is high, with fatal crash rates of teen drivers higher than any other age group. New approaches to reduce teen traffic fatalities are clearly needed. METHOD: A possible approach to reduce the incidence of teen driver crashes and fatalities is through the use of vehicle-based intelligent driver support systems. To be most effective, the system should address the behaviors associated with an overwhelming number of teen fatal crashes: speed, low seatbelt use, and alcohol impairment. In-vehicle technology also offers an opportunity to address the issue of inexperience through enforcement of certain Graduated Driver's License provisions. RESULTS: To fully understand the capability of such technologies, there should be a concerted effort to further their development, and human factors testing should take place to understand their effects on the driver. IMPACT: If successfully implemented, a Teen Driver Support System (TDSS), such as the one described here, could significantly decrease the number of teens killed in traffic crashes.     

An Avoidable Tragedy at the Sea Cliff (Rincon) Oil Field

Three men were killed and four others were injured during a well drill operation on Hobson Well C-10A in the Sea Cliff Oil Field (also known as Rincon Oil Field), in Ventura County, California, United States, on August 10, 1994, as a result of errors made by the work supervisors at the site. The oil field was under management by Vintage Petroleum, Ltd., which was sued for negligence by the families of the deceased and injured. The coroner's autopsy examination concluded that the cause of the deaths was due to the inhalation of the toxic gas carbon monoxide (CO). This gas was assumed to have been released from the firing of high-energy guns (HEGs) using carbon-rich explosive pentaerythritol tetranitrate (PETN) in an oxygen-depleted environment, during a fracking operation by Schlumberger Corporation on Well C-10A. The author of this article was appointed as an expert witness by Schlumberger to evaluate if the coroner's conclusion was correct. A series of chemical analytical analyses were conducted on the vapor phase of samples, in addition to dissolved components in water from Well C-10A and two adjacent wells. Stable isotope analyses were also conducted on hydrogen (H₂), methane (CH₄), nitrogen (N₂), CO, and water (H₂O) 3 weeks after the accident, as well as on four additional occasions from September to December 1994. Control test analyses were performed on the products from HEG firings, using the same explosives as those used in the perforation of Well C-10A in control chambers at a Schlumberger facility in Houston, Texas. The conclusion reached was that the dominant products of PETN detonations are H₂, CH₄, CO, and N₂. However, the isotope ratios (D/H and ¹³C/¹²C) of methane in the control experiments were different in Well C-10A, following the detonation on August 10, 1994, than those resulting from controlled PETN explosions. The conclusion reached in this study was that the fracking of the well at a depth of around 2,150 ft had increased the permeability of the sediment layers in the Padres Zone at that depth to allow the rapid release of a large quantity of natural gas, primarily CH₄, which supersaturated the water in the well. This event caused the formation of a large bubble, which ballooned out of the well to the surface, displacing air in the location where the men were working, and thus causing asphyxiation, which resulted in the death of the three men. The judge accepted this interpretation.     

Fatal pedestrian crashes on interstates and other freeways in the United States

Introduction: More than 800 pedestrians die annually in crashes on interstates and other freeways in the United States, but few studies have examined their characteristics. Method: Data from the Fatality Analysis Reporting System on pedestrians fatally injured during 2015–2017 were analyzed. Chi-square tests compared characteristics of pedestrians killed on interstates and other freeways with those that died on other roads, and across crash types among freeway deaths. Land use characteristics of locations where pedestrians were killed while crossing freeways in a large state (California) were identified using Google Earth. Results: A larger proportion of pedestrians killed on freeways died on dark and unlit roads (48% vs. 32%), were male (78% vs. 68%), or were ages 20–44 (55% vs. 32%) compared with pedestrians killed on other roads. Crossing (42%) was the most common crash type among pedestrian deaths on freeways, followed by disabled-vehicle-related crashes (18%). Pedestrians who died while crossing more often had blood alcohol concentrations ≥ 0.08 g/dL (40%) than those in disabled-vehicle-related (22%) or other crashes (34%). Deaths in crossing crashes were more likely than other freeway deaths to occur on urban roads (81%), at speed limits ≤50 mph (13%), or between 18:00 and 23:59 (49%), and 58% of crossing crashes analyzed for land use were located between residential and other (e.g., commercial, recreational) uses. Over a third (37%) of deaths in disabled-vehicle-related crashes occurred at speed limits ≥70 mph. Conclusions: A surprising proportion of pedestrian deaths occur on controlled-access roads not designed for walking. Countermeasures for these crashes need to be implemented to see meaningful reductions in pedestrian fatalities overall. Practical applications: Improving roadway and vehicle lighting, requiring reflective warning devices for marking disabled vehicles, constructing pedestrian overpasses and underpasses in areas frequently crossed, and promoting alternative means of traveling between residential and commercial areas could help.     

Spatial and temporal patterns and the socioeconomic impacts of landslides in the tropical and mountainous Colombian Andes

Landslides are a natural hazard that presents a major threat to human life and infrastructure. Although they are a very common phenomenon in Colombia, there is a lack of analysis that entails national and comprehensive spatial, temporal, and socioeconomic evaluations of such events based on historical records. This study provides a detailed assessment of the spatial and temporal patterns and the socioeconomic impacts associated with landslides that occurred in the country between 1900 and 2018. Two national landslide databases were consulted and this information was complemented by local and regional landslide catalogues. A total of 30,730 landslides were recorded in the 118-year period. Rainfall is the most common trigger of landslides, responsible for 92 per cent of those registered, but most fatalities (68 per cent) are due to landslides caused by volcanic activity and earthquakes. An ‘fN curve’ revealed a very high frequency of small and moderate fatal landslides in the time frame.