Influence of environmental street characteristics on walking route choice of elderly people

Walking is an important source of outdoor physical activity among elderly people. In order to devise measures aimed at encouraging walking among the elderly it is important to understand how the local environment influences the walking behaviour of elderly people. Here, a model describing the influence of environmental street characteristics on the walking route choice of elderly people is presented. Techniques adapted from the field of transportation research were employed within the model. Data concerning the walking route choice to specific destinations reported by 364 independently living elderly residents (55–80 years) from three Dutch urban districts were collected. Route choice was modelled within a ‘Geographic Information System’ (GIS) database by using ‘resistance factors’ to describe the resistance to walking of street sections (i.e. links) within the street network. These factors were optimized by minimizing the difference between the estimated and the reported number of trips along each link. This is, to the authors' knowledge the first time that this technique has been applied within this context. The influence of link characteristics on link resistance was investigated by multivariate linear regression. The first results of the route choice model and the influence of street characteristics on route choice are reported and discussed.     

Simultaneous gas chromatographic determination of chlorpyrifos and its impurity sulfotep in liquid pesticide formulations

An analytical method for simultaneous determination of the active substance (chlorpyrifos) and its relevant impurity (sulfotep) in commercial pesticide formulations has been developed and validated. The proposed method entails extraction of the analytes from samples by sonication with acetone and analysis by gas chromatography-flame ionization detection (GC-FID). The proposed method was characterized by satisfactory accuracy and precision. The repeatability expressed as relative standard deviation (RSD) was lower than the acceptable values calculated from the modified Horwitz equation whereas individual recoveries were in the range of 98–102% and 80–120% for chlorpyrifos and sulfotep, respectively. The limit of quantification (LOQ) for the impurity (sulfotep) was 0.003 mg mL^?1 corresponding to the maximum permitted level according to Food and Agricultural Organization of the United Nations (FAO) specifications for the active substance (chlorpyrifos) being 3 g kg^?1 of the chlorpyrifos content found. The main advantage of the proposed method was a considerable reduction in the analysis time since both analytes were determined based on a single injection into the GC-FID. Analysis of real samples of commercial pesticide formulations confirmed fitness-for-purpose of the proposed method.     

Solid olive waste in environmental cleanup: oil recovery and carbon production for water purification

A potentially-economic three-fold strategy, to use solid olive wastes in water purification, is presented. Firstly, oil remaining in solid waste (higher than 5% of waste) was recovered by the Soxhlet extraction technique, which can be useful for the soap industry. Secondly, the remaining solid was processed to yield relatively high-surface area active carbon (AC). Thirdly, the resulting carbon was employed to reversibly adsorb chromate ions from water, aiming to establish a water purification process with reusable AC. The technique used here enabled oil recovery together with the production of a clean solid, suitable for making AC. This process also has the advantage of low production cost.     

Passive monitoring of nitrogen dioxide in urban air: a case study of Durban metropolis, South Africa

To devise and implement strategies to manage the quality of urban air, a metropolis needs air pollution data on which an air quality management plan can be formulated. Although air pollutants can come from several sources, many reports suggest that nitrogen dioxide from motor vehicle emissions is the major contributor to air pollution in cities. Since vehicles stop or move slowly through traffic intersections, concentrations of nitrogen dioxide (NO(2)) are expected to be relatively high at these sites. Inexpensive Ogawa passive samplers were placed at selected traffic intersections in the Durban Metropolis to trap the NO(2) which was then analysed by a sensitive laboratory-based method. The data obtained by this method was compared with data from sophisticated system comprising an active sampler cum on-line chemiluminescence detector. The sampling was done over a twelve month period to cover all seasons. Statistical analysis of the data showed that there was no significant difference between the means for the two methods. This study has established that an Ogawa passive sampler may be used as an economical and reliable collector for NO(2) in ambient air under varying climatic conditions. Further, the analysis method using a UV-Visible spectrophotometer was sensitive enough to detect NO(2) at the 10-20 ppb level. The cost of the method should be well within the budgets of most municipalities and it would motivate them to develop policies to alleviate traffic congestion.     

活性焦烟气脱硫技术的探讨

本文主要介绍了活性焦的微晶结构、微孔结构、活性焦性能、活性焦烟气脱硫技术工艺及特点。该技术具有流程简单、净化效果好、排烟温度高、节水、不产生二次污染、可回收硫资源等优点。活性焦烟气脱硫技术符合我国国情和经济可持续发展的要求,应加快推广应用,解决我国大气污染的同时回收宝贵的硫资源。     

Dynamics of dust explosions suppression by means of extinguishing powder in various industrial conditions

In industrial conditions, there are different kinds of installations endangered by an explosion of dust–gas mixtures. In order to prevent them from any consequences of potential explosions, active protection systems which use extinguishing powders, as the suppressing material, are more and more widely applied. It often happens that the industrial installations are additionally endangered by an action of mechanical vibrations. In the above-mentioned conditions, the extinguishing powder tends to aggregate, making the process of dispersing it in the protected areas more difficult.

The results of research into optimization of the shape, number of igniters and miniaturization of the explosive charge mass are presented. In case of occurrence of the mechanical vibrations in the installations that cause aggregation of the suppressing powder, the best solution was modification of the perforated combustion chamber located inside the extinguisher. As a result of that, a certain amount of gases generated in the course of combustion of the main charge is directed over the membrane, where the gases crash a layer of aggregated powder. Thus, the process of pushing the powder out from a container towards the dispersing head improves considerably and consequently increases the efficiency of the explosion-suppressing process.     

上海花园饭店污水处理装置的改进

1 概况 上海花园饭店,污水处理装置的全套设备从日本进口,占地面积约636m~2,采用接触曝气法处理污水。整套设施的主要技术指标包括:纳污量:800m~3/d;进水BOD≤250mg/L;进水SS≤250mg/L;出水BOD≤20mg/L;出水中大肠菌≤3000个/;制作泥饼307kg/d。     

Kinetic study on photocatalytic degradation of Acid Orange 52 in a baffled reactor using TiO2 nanoparticles

In this study, a baffled photocatalytic reactor was used for the treatment of colored wastewater containing the azo dye of Acid Orange 52(AO52). A study on the active species of the photocatalytic process using TiO_2 nanoparticles indicated that hydroxyl radical and superoxide have the greatest contribution to the dye degradation process respectively.Given that a level of biological oxygen demand/chemical oxygen demand(BOD5/COD) equal to 0.4 was achieved after about 5 hr from the beginning of the experiment, the reactor seems to be capable of purifying the wastewater containing AO52 dye after this time in order to discharge into a biological treatment system to continue the treatment process.The results of the liquid chromatography-mass spectrometry(LC-MS) test showed that during the first 4 hr of the experiment, with the breakdown of the azo bond, the contaminant was decomposed into the benzene annular compounds with less toxicity indicating a reduction in the toxicity of wastewater after removing the dye agent. The study on the kinetics of these reactions followed the pseudo-first-order kinetic model in all conditions and corresponded well to Langmuir–Hinshelwood model. According to the kinetic model for the simultaneous occurrence of possible pathways, the kinetic constant of production and degradation of intermediate products in optimal conditions was estimated to be between 0.0029 and 0.0391 min~(-1).     

地震和断裂活动对青藏铁路高原多年冻土区铁路影响分析

青藏铁路是世界上海拔最高的铁路。通过沿线青海及西藏的地震情况和西大滩断裂带、昆仑山垭口断裂以及不冻泉断裂带的多年观测数据和青藏铁路线路的实际穿越段的地质特点,可以看出,青藏铁路格尔木—拉萨段沿线地震活动频繁、断裂大量发育,不同性质、不同类型、不同特点的活动断裂给青藏铁路的工程安全带来不同程度的影响,并产生和诱发不同类型的地质灾害。一旦在铁路下方沿活动断层形成移动冰丘,将导致铁路路基隆起和铁轨变形。断裂运动不仅孕育了地震,还诱发了不均匀冻胀、构造裂缝、移动冰丘等地质灾害,影响线路工程的安全,增加维护费用。笔者着重4方面分析地震断裂活动对青藏铁路的危害性:断裂活动导致路面变形和工程破坏;断裂活动与非均匀冻胀造成路基强烈变形;构造裂缝带及其工程危害;冻土地区的地震和断裂与保护冻土的工程措施产生矛盾,给出了设计和施工中应该考虑的问题并提出从铁路的勘察设计、施工组织、施工过程中采用各种措施将地震以及断裂活动对铁路的损害程度降低到最小。     

活性污泥膨胀上浮的原因分析与对策

污泥膨胀是活性污泥法污水处理的一个难题，尤其在处理高负荷的石化污水中。文章分析了引起污泥膨胀、上浮的主要原因，对引起污泥上浮的因素进行了探讨，提出了控制污泥膨胀、上浮的几种对策。