Sorption of tylosin and sulfamethazine on solid humic acid

Tylosin(TYL) and sulfamethazine(SMT) are ionizable and polar antimicrobial compounds,which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid(HA) may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions(pH, ionic strength) was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing p H(2.0–7.5), implying that the primary sorption mechanism could be due to cation exchange interactions between TYL~+/SMT~+ species and the functional groups of HA.Increasing ionic strength resulted in a considerable reduction in the K_d values of TYL and SMT,hinting that interactions between H bonds and π–π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared(FT-IR) and ~13C-nuclear magnetic resonance(NMR) analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds,respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions.     

开封市公园地表灰尘PAHs污染与健康风险评价

应用气相色谱-质谱联用仪(GC-MS)测定了开封市相国寺、铁塔公园、龙亭公园、清明上河园等4个公园的53个地表灰尘样品中的16种优控多环芳烃(PAHs)含量,并分析了PAHs的来源、组成、污染水平和健康风险.结果表明:样品∑PAHs含量在332.20~7535.10μg·kg-1之间,平均值为1320.10μg·kg-1,其中,单体PAHs以菲、蒽、荧蒽、芘、苯并(a)蒽、苯并(b)荧蒽和苯并(a)芘等4~5环化合物含量较高;相国寺、铁塔公园、龙亭公园灰尘分别达到重度、中度、轻度PAHs污染,清明上河园未检测到PAHs污染.终生癌症风险增量模型(ILCRs)评价结果显示,儿童健康风险高于成人,皮肤接触灰尘PAHs是导致儿童和成人高风险的最主要暴露途径,其次是手口摄入途径.灰尘PAHs综合致癌风险(CR)的顺序为相国寺铁塔公园龙亭公园清明上河园,其中,相国寺的CR超过10-6,存在人体可耐受的致癌风险,其他公园不存在健康风险.影响公园灰尘PAHs含量、污染程度和健康风险的因素非常复杂,是建园时间、地理位置、公园性质、游客密度及周边环境状况等多种因素综合的结果.灰尘PAHs主要来源于石油、煤和生物质不完全燃烧,以及石油泄漏等.     

湘西金矿沃溪矿区通风系统改造研究

基于矿井目前通风系统存在的问题,运用子域分区单元子系统通风方式、不同类型的中段通风网路、风流净化、入风流预冷、自然风压的合理利用等技术对通风系统进行 了优化改造.系统改造后,风量充足,风流稳定,通风能力与生产能力相适应,较好地解决了深部通风问题,取得了显著的技术效果和节能效益.     

Moisture distribution in sludges based on di erent testing methods

Moisture distributions in municipal sewage sludge, printing and dyeing sludge and paper mill sludge were experimentally studied based on four di erent methods, i.e., drying test, thermogravimetric-di erential thermal analysis (TG-DTA) test, thermogravimetricdi erential scanning calorimetry (TG-DSC) test and water activity test. The results indicated that the moistures in the mechanically dewatered sludges were interstitial water, surface water and bound water. The interstitial water accounted for more than 50% wet basis (wb) of the total moisture content. The bond strength of sludge moisture increased with decreasing moisture content, especially when the moisture content was lower than 50% wb. Furthermore, the comparison among the four di erent testing methods was presented. The drying test was advantaged by its ability to quantify free water, interstitial water, surface water and bound water; while TG-DSC test, TG-DTA test and water activity test were capable of determining the bond strength of moisture in sludge. It was found that the results from TG-DSC and TG-DTA test are more persuasive than water activity test.     

离子色谱检测在火电厂水汽品质监督中的应用

针对火力发电厂水汽品质,运用离子色谱分析技术进行查定。应用结果表明:离子色谱分析技术具有分析速度快、灵敏度高、结果准确的优点,对监督现场化学设备运行水平具有重要意义。     

五氯酚(PCP)高效降解菌Psendomonas sp.CS5的研究

从曾受五氯酚(pentachlorophenol,简称PCP,下同)污染废水的活性污泥中,经驯化富集和分离筛选获得一株PCP降解菌,菌号为CS-W-98-5.在24h内该菌降解w(PCP)=400×10     

基于居民视角的应急避难所优化配置研究

以虚拟区域和哈尔滨市道里区经纬街为研究区,以满足居民避难需求为目标,分别构建居民避难行动效率模型与应急避难所服务范围模型,并将二者进行耦合。先以虚拟区域说明利用耦合模型的适用性与可行性,再以研究区探讨居民避难所效率与应急避难所优化配置。研究结果表明:研究区现状应急避难所配置,在研究区有2处是应急避难所服务无法覆盖的范围。以耦合模型为基础,确定需要增加2个应急避难所,才能满足居民避难需求。该研究方法不仅为我国应急避难所优化配置理论与方法作了补充,其结果也为研究区及其他地区应急避难所优化配置提供了参考依据。     

Attack vulnerability of self-organizing networks

There are several self-organizing networks in the real world, and these networks severely affect the development of the modern society. This paper investigates the vulnerability of self-organizing networks subject to malicious attacks according to a new framework. Assuming the initial load of node i as L_i=αk_i+(1-α)∑_j∈Γik_j with k_i and Γ_i being the degree and the set of neighbor nodes of the node i, where α is a tunable parameter and control the strength of the initial loads of nodes. The node with the maximum degree is considered as the attacked node, and with the changes of the parameter α, cascading failures will be investigated in this paper. Local redistribution rule has been adopted to study the cascading breakdowns of the US power grid and IEEE-118 networks. Additionally, the capacity of the node i is defined as C_i = (1 + β)L_i, the critical threshold β_c of the US power grid and IEEE-118 networks will be obtained from the evolutional process of cascading failures. Finally, an optimal design of US power grid network is given in this paper.     

安全生产标准化在胜利油田的实施建义

2004年,国家安全监管局印发了《关于开展安全质量标准化活动的指导意见》,煤矿、非煤矿山、危险化学品、烟花爆竹、冶金、机械等行业均     

常州酸焦油的无害化焚烧处理方法探索

以一种典型的液态危险废弃物--常州酸焦油为研究对象,添加一定比例的电石渣混合以后,通过管式炉不同工况下的焚烧实验来研究烟气中污染物的排放特性.实验结果表明,二氧化硫的排放受焚烧温度影响很大,700℃以下未能检测到有SO2析出,800℃以上硫转化率曲线呈快速上升趋势,900℃时物料中约1/5的硫转化为气态,至1000%时,有一半的硫转化为气态.同时,增大空气流量会对SO2排放产生一定的正面影响.