滨海盐渍土地基灌注桩承载性状试验研究

结合滨海盐渍土地基嵌岩灌注桩竖向静载试验。对桩身轴力传递、桩周围盐渍土层岩层侧摩阻力发挥性状以及桩端阻力变化规律进行了分析。讨论了对受施工质量影响的2^#试验桩桩身轴力传递规律和侧阻力发挥性状的异常情况，所得结果可供滨海盐渍土地基桩基工程的设计、施工和检测工作参考。     

一株菲降解细菌的分离及其特性

利用平板熏蒸和双氧加合酶活性测定的方法 ,从大庆油田水体中筛选出 1株对菲具有降解活性的细菌 ,Phx1.在LB培养基中 ,能将浓度为 10 0 μg/mL的菲在 2 4h内完全降解 .与无机盐培养基相比 ,LB和牛肉膏蛋白胨培养基能促进此菌对菲的降解 ,尤其能促进对中间产物的进一步转化 .经质粒消除证明 ,Phx1具有 2个质粒 ,且较大的 1个对菲的降解是必须的 .通过对其形态、生理生化特性 ,16SrDNA序列分析 ,鉴定Phx1为土壤杆菌属细菌 ,其 16SrDNA序列与Agrobacterium tumefaciensUP 3、Agrobacterium albertimagni的相似性最高 ,分别达到 97 8%和 96 6 % ,但对向日葵的致瘤实验为阴性 .     

Effects of drawdown scenario on retrogressive lateral erosion in a reservoir

The drawdown of reservoirs behind dams is an important management strategy (e.g., for removal of aging infrastructure, flushing of sediment), and an opportunity to study erosional processes. A numerical model was developed to examine retrogressive bank erosion across reservoir drawdown scenarios and to evaluate factors controlling the rate, volume, and mechanisms of lateral erosion. Modeled processes included dynamic drawdown of groundwater, sequential slope failures via limit equilibrium analysis, and retrogression considering stress interaction between failing blocks. Field measurements were coupled with Staged, Slow, and Rapid drawdown scenarios. Results highlight the importance of including retrogression as an avenue for lateral erosion, as sequential block failures were found to occur in all scenarios except Slow drawdown. This result indicates that bank stability models without some means of characterizing the evolution of slope failure during drawdown are likely underestimating bank failure rates and volumes. In contrast, dynamic groundwater was not found to be a dominant control for any drawdown scenario. Model results also demonstrate that the drawdown increment is a first-order control on slope instability via the development of drained or undrained conditions. A majority of failures occurred under undrained conditions. To maximize slope stability, using slow drawdown to activate internal friction under drained conditions is essential. The design of the drawdown rate created a tradeoff between the amount of impact created and when the impact is produced. The study also articulated the need for coupling models and field observations for rapidly changing systems.     

Monitoring heavy metal concentrations in leachates from a forest soil subjected to repeated applications of sewage sludge

The aim of the study was to establish whether the repeated application of sewage sludge to an acid forest soil (Dystric Cambisol) would lead to short-term groundwater contamination. Sludge was applied at four loading rates (0, 2.4, 17 and 60 Mg ha⁻¹) in two consecutive years and leachates were analysed. Heavy metal inputs to soils at the lowest dose were below EC regulations but, at higher doses, limits for Zn, Cd, Cr and Ni were exceeded. Repeated application of sludge at 60 Mg ha⁻¹ resulted in significantly (P < 0.05) higher concentrations of Zn, Cd, Cr and Ni in the leachates than with other treatments. The drinking water standards for Cd and Ni were surpassed in all treatments. Control plots were contaminated by groundwater flow despite the existence of buffer zones between plots. This complicated interpretation of the results, highlighting the importance of careful design of this type of experiment.     

Variable Source Area Hydrology Modeling with the Water Erosion Prediction Project Model

In nondegraded watersheds of humid climates, subsurface flow patterns determine where the soil saturates and where surface runoff is occurring. Most models necessarily use infiltration‐excess (i.e., Hortonian) runoff for predicting runoff and associated constituents because subsurface flow algorithms are not included in the model. In this article, we modify the Water Erosion Prediction Project (WEPP) model to simulate subsurface flow correctly and to predict the spatial and temporal location of saturation, the associated lateral flow and surface runoff, and the location where the water can re‐infiltrate. The modified model, called WEPP‐UI, correctly simulated the hillslope drainage data from the Coweeta Hydrologic Laboratory hillslope plot. We applied WEPP‐UI to convex, concave, and S‐shaped hillslope profiles, and found that multiple overland flow elements are needed to simulate distributed lateral flow and runoff well. Concave slopes had the greatest runoff, while convex slopes had the least. Our findings concur with observations in watersheds with saturation‐excess overland flow that most surface runoff is generated on lower concave slopes, whereas on convex slopes runoff infiltrates before reaching the stream. Since the WEPP model is capable of simulating both saturation‐excess and infiltration‐excess runoff, we expect that this model will be a powerful tool in the future for managing water quality.     

The effectiveness of lane departure warning systems—A reduction in real-world passenger car injury crashes

Objective: The objective of this study was to estimate the safety benefits of in vehicle lane departure warning (LDW) and lane keeping aid (LKA) systems in reducing relevant real-world passenger car injury crashes.

Methods: The study used an induced exposure method, where LDW/LKA-sensitive and nonsensitive crashes were compared for Volvo passenger cars equipped with and without LDW/LKA systems. These crashes were matched by car make, model, model year, and technical equipment; that is, low-speed autonomous emergency braking (AEB) called City Safety (CS). The data were extracted from the Swedish Traffic Accident Data Acquisition database (STRADA) and consisted of 1,853 driver injury crashes that involved 146 LDW-equipped cars, 11 LKA-equipped cars, and 1,696 cars without LDW/LKA systems.

Results: The analysis showed a positive effect of the LDW/LKA systems in reducing lane departure crashes. The LDW/LKA systems were estimated to reduce head-on and single-vehicle injury crashes on Swedish roads with speed limits between 70 and 120 km/h and with dry or wet road surfaces (i.e., not covered by ice or snow) by 53% with a lower limit of 11% (95% confidence interval [CI]). This reduction corresponded to a reduction of 30% with a lower limit of 6% (95% CI) for all head-on and single-vehicle driver injury crashes (including all speed limits and all road surface conditions).

Conclusions: LDW/LKA systems were estimated to lower the driver injury risk in crash types that the systems are designed to prevent; that is, head-on and single-vehicle crashes. Though these are important findings, they were based on a small data set. Therefore, further research is desirable to evaluate the effectiveness of LDW/LKA systems under real-world conditions and to differentiate the effectiveness between technical solutions (i.e., LDW and LKA) proposed by different manufacturers.     

邻苯二酚双加氧酶传感器的研究

洋葱伯克霍尔德氏菌L68的细胞裂解液经硫酸铵分级沉淀后,依次经DEAE-SepharoseFastFlow柱层析,Hydroxyapatite柱层析和SephadexG-150凝胶过滤分离,提取到邻苯二酚双加氧酶.经SDS-PAGE检测,达到电泳纯.将酶反应与氧电极偶联,研究了检测水体中邻苯二酚的邻苯二酚双加氧酶传感器.以100mmol/L磷酸钠标准缓冲液(pH7.24)作为该酶传感器的的工作介质,在25℃条件下测得传感器对邻苯二酚标准液的工作曲线线性范围为0.2～3mmol/L,检测限为0.05mmol/L,响应时间为1min,平均回收率达到1.03%.