Manipulation of density and viscosity for the optimization of DNAPL recovery by alcohol flooding

Laboratory experiments demonstrate that in situ recovery of pooled tetrachloroethene (PCE) from porous media may be accomplished more efficiently using multiple-step alcohol floods than with single alcohol floods. To optimize flooding efficiency while maintaining a low risk of downward DNAPL mobilization, a three-step flooding process is developed employing an isobutanol preflood, a composite alcohol mainflood, and a polymer solution postflood. The density and viscosity of these solutions are manipulated to prevent the onset and propagation of viscous and gravitational fingers, while maintaining phase behavior critical for efficient miscible NAPL displacement. An aqueous partitioning preflood solution of 10% by volume (10% v) isobutanol reduces the NAPL density in situ to approximately 1.00 g/ml by swelling the NAPL prior to miscible displacement induced by the mainflood. The composite alcohol mainflood, containing 65% v ethylene glycol and 35% v 1-propanol maintains miscibility while achieving neutral buoyancy and near stable displacement of the NAPL. Aqueous solutions of xanthan gum polymer efficiently displace the mainflood, reducing viscous fingering associated with waterfloods. Two-dimensional experiments using the multiple-step technique achieve 99.8% DNAPL mass recovery using a total of 0.45 pore volumes of alcohol, illustrating greater recovery efficiency than previous alcohol flooding formulations under comparable conditions.     

HYDROLOGIC DESIGN CONSIDERATIONS OF CONSTRUCTED WETLANDS FOR URBAN STORMWATER RUNOFF1

ABSTRACT: The successful design of constructed wetlands requires a continuous supply of water or vegetation that can withstand drought conditions. Having a constant water source is the best alternative to insure species diversity throughout the season. Consequently, detention structure designs should be based on times between events as well as on hydrologic return periods, since between events is when most evaporation and infiltration losses are likely to occur. In arid or semi-arid environments, this is a difficult process because of long interevent times and seasonal changes in precipitation patterns. This discussion is predicated on the assumption that phytoplankton, epiphytic algae, and emergent vegetation require moist conditions to be effective at removing nutrients, metals and other pollutants. There are drought tolerant species of vegetation that can be used in constructed wetlands but it may take several days to re-establish the attached bacteria communities necessary for optimum pollutant removal. This paper examines a stochastic framework to examine the probability of extended dry periods based on historic rainfall data. The number of consecutive dry days is selected for a specified level of assurance. By multiplying this value by the sum of daily system losses, an overall pond volume can be determined that ensures a minimum depth of water. To illustrate the utility of the approach, the method is applied to a site in Spokane, Washington.     

脉冲放电等离子体治理甲苯废气放大试验研究

应用脉冲放电等离子体技术,在线板式反应器内对低浓度甲苯废气的治理进行放大试验.采用闸流管开关脉冲电源,其最大输出功率1kW,最大脉冲电压峰值100kV. 试验规模4～16m³·h^-1. 试验考察了峰值电压、重复频率、进口浓度和处理气量对甲苯去除率的影响.结果表明:峰值电场强度在9～12kV·cm^-1范围内增加,甲苯去除率相应明显提高;当处理气量为4 m³·h^-1、脉冲电压峰值69kV、进口浓度1 180mg·m^-3、重复频率300pps时, 甲苯的去除率可达88%;反应器的能量利用率在16g·(kW·h)^-1左右;甲苯的降解产物主要是CO₂和H₂O,还有少量CO. 结合甲苯去除率与能量密度、甲苯进口浓度的关系,建立反应器动力学模型,获得甲苯的反应速率常数为0.00356 L·J^-1. 为进一步优化放大反应器设计及与电源匹配提供了基础数据.     

保暖鞋鞋底保暖结构研究

本文结合鞋靴保暖功效学原理,重点研究了支撑式鞋垫和橡胶双密度胶底结构。通过实验确定了鞋底发泡层视密度的范围在0.75g/cm3～0.85g/cm3之间,发泡橡胶的拉伸和导热性能达到平衡,兼顾了保暖鞋的耐穿和防寒隔热性能。     

酒精蒸气/烟草粉尘两相混合体系最小点火能试验研究

在烟草加工的加香工序,挥发的酒精和搅拌混料产生的烟草粉尘形成气粉混合体系,其燃爆特性相较于单相烟草粉尘有较大变化。对20 L爆炸球进行了部分改造,可完成20℃～80℃环境温度、100%LEL以下酒精蒸气浓度、最大2 J电火花能量组合的气粉混合物的最小点火能测试。选用烘丝和加香烟草粉尘做对比,探究了环境温度和酒精蒸气浓度对酒精蒸气/烟草粉尘两相混合体系点火能的影响规律。结果表明：相同环境温度下,加香烟草粉尘的最小点火能比烘丝烟草粉尘低;加香粉尘、烘丝粉尘及混合体系的最小点火能随环境温度变化的趋势一致,均随温度的升高而降低;加入10%LEL的酒精蒸气后,相同温度下气粉混合体系的最小点火能低于单相烟草粉尘。随着环境温度的升高,二者的差值逐渐减小,酒精蒸气诱导烟草粉尘最小点火能降低的能力逐步减小甚至消失;在电点火条件下,当酒精蒸气浓度低于50%LEL时,气粉混合体系较难被点燃,当酒精蒸气浓度高于75%LEL时,混合体系较易被点燃。     

圆锥形喷嘴出口直径对水射流冲击动力特性的影响研究

为探讨喷嘴结构对水射流冲击动力特性的影响,以圆锥形喷嘴为研究对象,基于COMSOL数值模拟软件,建立不同出口直径的圆锥形喷嘴模型,研究出口直径对水射流冲击动力特性的影响。研究结果表明：圆锥形喷嘴水射流冲击煤岩体过程中,不同喷嘴出口直径下水射流流场分布特征相似,整个流场可分为集中区、发散区、回流区和卷吸区4个区域,随喷嘴出口直径增大,卷吸区逐渐消失,其余3个区域分布也明显减弱;煤岩体应力分布可分为中心应力集中区和两侧应力集中区,随喷嘴出口直径不断增大,中心应力集中区与两侧应力集中区的范围逐渐减小,当喷嘴出口直径为6 mm时,两侧应力集中区基本消失;主体段入口速度恒定条件下,圆锥形喷嘴优选以2～3 mm出口直径为宜,此时水射流冲击煤岩体效果较佳,且不会对喷嘴产生结构破坏。     

Fall-related emergency department visits involving alcohol among older adults

Problem: Falls are the leading cause of injury deaths among adults aged 65 years and older. Characteristics of these falls may vary with alcohol use. Objective: Describe and compare characteristics of older adult fall-related emergency department (ED) visits with indication of alcohol to visits with no indication. Methods: Using nationally-representative 2015 National Electronic Injury Surveillance System-All Injury Program data, we compared demographic characteristics for fall-related ED visits by indication of alcohol consumption. Alcohol-indicated ED visits were matched on age group, sex, treatment month, and treatment day to ED visits with no alcohol indication using a 1:4 ratio and injury characteristics (i.e., diagnosis, body part injured, disposition) were compared. Results and discussion: Of 38,640 ED records, 906 (1.9%) indicated use of alcohol. Fall-related ED visits among women were less likely to indicate alcohol (1.0%) compared to ED visits among men (3.8%). ED visits indicating alcohol decreased with age from 4.1% for those 65–74 years to 1.5% for those 75–84 and <1% for those 85+. After controlling for age-group, sex, and month and day of treatment, 17.0% of ED visits with no alcohol indication had a traumatic brain injury compared to 34.8% of alcohol-indicated ED visits. Practical applications: Alcohol-indicated fall ED visits resulted in more severe head injury than those that did not indicate alcohol. To determine whether alcohol use should be part of clinical risk assessment for older adult falls, more routinely collected data and detailed information on the amount of alcohol consumed at the time of the fall are needed.     

滆湖藻密度的时空分布及驱动因子分析

在2年内分季度调查滆湖浮游植物种群和水环境因子,分析藻密度的空间分布状况以及按时间序列的藻密度变化和浮游植物优势种群变化,分别采用"多元线性逐步回归法"和"偏相关系数法"进行藻密度驱动因子识别。结果表明,滆湖藻密度空间分布趋势为由北向南逐渐升高,年际间季节差异极显著。浮游植物的演替规律为冬、春季节以绿藻和硅藻为主,夏、秋季节蓝藻占绝对优势。通过比较2种统计方法的计算结果,确定全湖及中、南部湖区藻密度的驱动因子是温度和高锰酸盐指数,北部湖区藻密度的驱动因子是温度和硝酸盐氮,所有驱动因子对滆湖藻密度的影响均为正效应。在富营养化严重的滆湖,N,P营养盐已经不再是浮游植物生长的主要驱动因子,从统计方法的角度解释了部分环境因子没有入选为驱动因子的原因,并推断了其他可能的驱动因子。     

Ozone tolerance in Phaseolus vulgaris depends on more than one mechanism

Two bean cultivars with different sensitivity to ozone, i.e. the O₃-sensitive Cannellino and the O₃-tolerant Top Crop, were exposed to acute O₃-stress (165 nL L⁻¹) with the aim of evaluating physiological and biochemical traits that may confer O₃-tolerance. Stomatal conductance was smaller and the ability to dissipate excess energy, via regulated and unregulated nonphotochemical quenching mechanisms was greater in Top Crop than in Cannellino. These morphological and physiological-traits allowed the O₃-tolerant cultivar to compensate for the light-induced declines in Φ_PSII, to preserve photosystem II from excitation-energy, and likely to prevent the generation of ROS to a superior degree than the O₃-sensitive cultivar. Furthermore, the potential capacities to reducing the superoxide anion and H₂O₂ were significantly greater in Top Crop than in Cannellino. These findings are consistent with the early accumulation of H₂O₂, the almost complete disruption of cell structure, and irreversible damages to the photosynthetic apparatus observed in the O₃-sensitive cultivar.     

金沙江头塘小流域人工林有机碳及其剖面分布特征

采用野外调查、室内分析并结合相关的方法,研究探讨了金沙江头塘小流域7种不同植被恢复人工林土壤剖面层次有机碳(SOC)含量、有机碳密度(SOCD)和有机碳储量及分布特征。结果表明,不同林分类型及土层间土壤SOC含量存在明显差异:就整个土层(0~100 cm)而言,7种林分土壤SOC平均含量介于6.46±1.67~24.95±2.32 g·kg–1,大小依次为柳杉林旱冬瓜林圆柏林栓皮栎林圣诞树林墨西哥林藏柏林,且差异显著(p0.05);7种林分土壤SOC含量均出现表聚现象,从表层到深层都呈现递减趋势,且具有一定的规律性;7种林分土壤容重总体上均表现为随土层深度的增加逐渐增加,土壤容重表现为:柳杉林栓皮栎林圣诞树林圆柏林旱冬瓜林墨西哥柏林、藏柏林;7种林分土壤有机碳密度垂直分布和土壤有机碳含量垂直分布特征一致,随土层深度增加土壤有机碳密度减少,以表土10 cm的土壤有机碳密度最大;有机碳储量均随着土层加深所占比例逐渐降低,同时土壤有机碳主要集中于土层0~40 cm内,分别占总有机碳的65.60%(圣诞树林)、63.16%(旱冬瓜林)、54.41%(墨西哥柏林)、58.56%(圆柏林)、62.96%(藏柏林)、61.70%(栓皮栎林)和56.37%(柳杉林),0~40 cm土层土壤有机碳占总有机碳的百分比均达到50%以上。