Biosorption of cesium（Ⅰ） from aqueous solution by a novel exopolymers secreted from Pseudomonas fluorescens C-2： Equilibrium and kinetic studies

The biosorption characteristics of Cs(I) ions from aqueous solution using exopolymers (PFC02) produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and initial concentration. pH played a major role in the adsorption process, and the optimum pH for the removal of Cs(I) was 8.0. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of the Cs(I) ions by PFC02. The Lagergren first-order, pseudo second-order kinetic and intraparticle diffusion models were used to test the kinetic data. Langmuir model and D-R model fitted the equilibrium data better than the Freundlich isotherm. The monolayer adsorption capacities of PFC02 as obtained from Langmuir isotherm at 25°C was found to be 32.63 mg/g. From the D-R isotherm model, the mean free energy was calculated as 26.73 kJ/mol, indicating that the biosorption of cesium was chemisorption. The biosorption process was rapid, and the kinetic rates were best fitted to the pseudo second-order model, which indicated the biosorption process operated through chemisorption mechanism. FT-IR analysis of PFC02 showed the possible functional groups responsible for cesium adsorption were hydroxyl, carboxyl, carbonyl and sulphonate groups. SEM analysis showed the porous structure of the material while EDX analysis confirmed the adsorption of Cs(I) on PFC02. Cesium adsorbed onto the PFC02 could be desorbed efficiently using 1 mol/L HNO3, and the enrichment factor was 50.0. Furthermore, PFC02 could be reused five times with only about 8.25% regeneration loss. The developed method was successfully utilized for the removal of Cs(I) ions from aqueous solution.     

Estimation and comparison of night-time OH levels in the UK urban atmosphere using two di erent analysis methods

Night-time OH levels have been determined for UK urban surface environments using two methods, the decay and steady state approximation methods. Measurement data from the UK National Environmental Technology Centre archive for four urban sites (Bristol, Harwell, London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study. Three reactive alkenes, namely isoprene, 1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method. Hourly measurements of NO, NO2, O3, CO and 20 VOCs were used to determine night-time OH level using the steady state approximation method. Our results showed that the night-time OH levels were in the range of 1 105–1 106 molecules/cm3 at these four urban sites in the UK. The application of a t-test of these analyses indicated that except Bristol, there was no significant di erence between the OH levels found from the decay and steady state approximation methods. Night-time levels of the OH radical appeared to peak in summer and spring time tracking the night-time O3 levels which also passed through a maximum at this time.     

阿拉巴马大学：推进研究中心

每年,20名航空和机械工程专业的学生可以用8个月时间来设计,建造,和试飞火箭,飞行高度可达1609米。 此前,学生建造了一枚约16公斤重,2．6米长的碳纤维火箭,搭载了先进的数据收集系统。     

基于WebGIS的包头市环境地理信息系统平台搭建

本文首先综述了包头市环境地理信息系统平台的总体结构、功能模块、数据构成等,然后着重阐述EGIS平台下的环保数据构成、异构异地数据集成的关键技术和空间数据库与多元数据库的关联接口,最后论述了建设该平台的设计方法和平台特点。     

怒吼的巨浪——海啸

给地球以重创的＂311＂日本9.0级地震引发的巨大海啸,至今令人惊魂未定,海啸这一名词则被越来越多的世人所点击和热议。海啸是由海底地震或风暴等造成的海面恶浪并伴随巨响的具有强大破坏力的现象。海啸在许多西方语言中被称为＂tsunami＂,该词源自日语＂津波＂,     

国家环境数据共享与服务体系研究

结合我国环境数据共享与服务面临的问题,对国家环境数据共享与服务体系的时代背景、概念和实质、技术框架、主要建设内容等进行了研究。指出国家环境数据共享与服务体系是政府主导建设的环境信息资源网,核心由三级环境数据中心、依托于四级专网的环境数据传输与交换平台以及分别依托于内网、专网和互联网的各级共享服务门户构成。     

一切均不可恃——"深水地平线"钻井平台爆炸事故的启示

北京时间2010年4月21日11:00,位于美国路易斯安那州墨西哥湾的"深水地平线"(Deepwater Horizon)钻井平台在钻进作业过程中发生爆炸,并随后引发大火。平台在持续燃烧36小时后沉入海底,造成11人失踪和17人受伤(其中7人重伤)。事故同时造成海底井控设备严重损坏,地下原油通过失去控制的井口持续外溢,累计时间长达87天。泄漏而出的原油对墨西哥湾生态环境的破     

自然贮存场自然环境剖面归纳处理

针对某自然贮存场近几年的自然环境因素数据,应用小波分析理论对温度数据的周期分量和随机分量进行了分离.在数据分离的基础上,根据阿仑尼斯方程对年温度数据的周期分量,进行了等效平均,获得以热天、冷天划分的年恒定温度剖面.根据Manson-coffin模型对温度数据的随机分量进行了等效循环处理,最后综合得到贮存场的试验室模拟试...     

低能耗 高增长 高产出 天津全年工业利润首次超过千亿元

天津市经济和信息化委员会提供的最新数据显示,2010年全市工业增加值总量达到4410亿元,增长23.7%,增速居全国第一,拉动全市生产总值增长11.7个百分点。利润首次超过千亿元,达到1136.4亿元,同比增长68.7%,     

基于眼动数据的管制员注意力特征评价

为提高管制员培训的针对性和有效性,提升管制过程的安全性,提出使用注意力稳定性、注意力分配与转移和注意力广度3个指标,作为注意力特征的评价指标;设计并开展管制过程模拟管制试验,采集分析36名成熟管制员的眼动数据;提出选取兴趣区访问次数方差(VVC)、马尔可夫转移概率(MTP)和特情反应时间(RT)3个参数,将其作为刻画注意力特征3个评价指标对应的量化参数值,再使用K-Means聚类分析法对管制员的注意力特征进行分类,得到管制员注意力特征的评价值的结果分类区间,并对比评价结果与教员打分结果。结果表明：根据注意力特征,将管制员分成4类,一类为最优,四类为最差。优秀管制员具有注意力稳定性好、注意力分配合理、注意广度大和对特情敏感的特点,其量化参数值包括：VVC为13.48～95.46,MTP为0.03～0.22,RT为3～31 s。