Effects of soiling and cleaning on the reflectance and solar heat gain of a light-colored roofing membrane

A roof with high solar reflectance and high thermal emittance (e.g., a white roof) stays cool in the sun, reducing cooling power demand in a conditioned building and increasing summertime comfort in an unconditioned building. The high initial solar reflectance of a white membrane roof (circa 0.8) can be lowered by deposition of soot, dust, and/or biomass (e.g., fungi or algae) to about 0.6; degraded solar reflectances range from 0.3 to 0.8, depending on exposure. We investigate the effects of soiling and cleaning on the solar spectral reflectances and solar absorptances of 15 initially white or light-gray polyvinyl chloride membrane samples taken from roofs across the United States. Black carbon and organic carbon were the two identifiable strongly absorbing contaminants on the membranes. Wiping was effective at removing black carbon, and less so at removing organic carbon. Rinsing and/or washing removed nearly all of the remaining soil layer, with the exception of (a) thin layers of organic carbon and (b) isolated dark spots of biomass. Bleach was required to clear these last two features. At the most soiled location on each membrane, the ratio of solar reflectance to unsoiled solar reflectance (a measure of cleanliness) ranged from 0.41 to 0.89 for the soiled samples; 0.53 to 0.95 for the wiped samples; 0.74 to 0.98 for the rinsed samples; 0.79 to 1.00 for the washed samples; and 0.94 to 1.02 for the bleached samples. However, the influences of membrane soiling and cleaning on roof heat gain are better gauged by fractional variations in solar absorptance. Solar absorptance ratios (indicating solar heat gain relative to that of an unsoiled membrane) ranged from 1.4 to 3.5 for the soiled samples; 1.1 to 3.1 for the wiped samples; 1.0 to 2.0 for the rinsed samples; 1.0 to 1.9 for the washed samples; and 0.9 to 1.3 for the bleached samples.     

原子吸收光谱仪的背景校正

介绍了原子吸收光谱仪的５种主要的背景校正技术（邻近谱线技术，连续光源法，塞曼法，自吸法及连续光源单色器波长调节法ＣＥＷＭ）及其主要产品，分析评述了各种校正技术的原理，特点及其应用状况。     

利用焦炭吸附进行燃煤烟气脱硫脱氮技术的研究

介绍一种干法烟气脱硫脱氮工艺方法 ,利用一种非常容易获得炭质吸附材料经过简单的工艺处理后 ,达到燃煤烟气脱硫脱氮效果 ,整个过程不产生二次污染     

人工养殖与野生扬子鳄卵中重金属含量分析

以原子吸收分光光度法，测定了人工养殖与野生的扬子鳄卵中Cu、Zn、Cd、Pb等重金属元素的含量，并对上述4种元素的分布状况和差异性进行了探讨。实验表明，人工繁殖卵中重金属元素含量高于野生卵，人工饲养过程中所提供的饮水和饲料中重金属元素含量高于自然界，值得关注和重视。     

甲酯大气污染防治的研究

采用十三烷吸收大气中的MA（或MMA），实验表明，该方法处理MA（或MMA）的大气污染是行之有效的。处理的最佳工艺条件为吸收温度20℃，吸收压力0．1MPa，气流速度以低速为宜，当吸收剂十三烷中MA浓度低于8．11％，（若MMA则低于9．00％），排放的尾气中MA（MMA）浓度小于10mg／L。     

伏安法测定地下水中的氟

本文采用三电极系统（工作电极：玻碳电极；参比电极：甘汞电极；辅助电极：铂电极）研究了Pr（Ⅲ）－ALC－F体系吸附波的特性。在pH＝1．0的六次甲基四胺、硝酸溶液中，峰电位Ep＝-0.66V（vs．SCE）处，峰电流与F浓度在1×10－7至1×10－5mol／L范围内呈线性关系，检出限为：8×10－8mol／L，精密度为；0．7％。本法适用于各种样品的分析，具有灵敏度高，抗干扰能力强，试验简便无毒的特点。用该方法测定了地下水中的氟离子，结果令人满意。     

石墨炉原子吸收光谱法测定水中痕量铜、铅、镉

用石墨炉原子吸收分光光度法对水中痕量铜、铅、镉样品进行测定。结果表明,采用合适的仪器和石墨管升温程序条件,并注意进样针位置调节和石墨管的选择,测定的精密度和准确度好,灵敏度高,能满足水中痕量样品的分析。     

火焰原子吸收分光光度法检测矿区环境的常见重金属

在红河州某矿区周围的土壤、池塘、鱼塘采集若干土壤、水样品.用氢氟酸-高氯酸-浓硝酸消化土壤样品,用硝酸处理水样品.实验中,原子吸收分光光度法的平均相关系数≧0.99906;测定元素的相对标准差从0.27%～1.67%,其平均相对标准偏差为1.005%;样品的回收率在102,8%～111.5%之间,表明该法可用于环境中的土壤样品和水样品中重金属元素的准确测定.在仪器的最佳工作状态,使用FAAS法检测矿区环境中的铅(Pb)、铜(Cu)、铬(Cr)、汞(Hg)的含量;依此来发现矿区周围环境的重金属分布规律和周围环境的安全性.     

Stability of green fluorescent protein using luminescence spectroscopy: is GFP applicable to field analysis of contaminants?

Green fluorescent protein (GFP) was first isolated in the early 1970s for experimental use from coelenterates or the Pacific jellyfish. Aequorea victoria (Morin and Hastings, 1971). GFP has since become a favored biomarker in the photophysical analysis of molecular and cell biology because of its strong intrinsic visible fluorescence and the feasibility of fusing it to other proteins without affecting their normal functions (Creemers et al., 2000). Here we report using Bacillus subtilis expressing GFP to evaluate the influence of different environmental pH conditions on GFP fluorescence. Emission acquisitions were configured to excite at 471 nm and detect at an emission from 490 to 650 nm at 1-nm increments. Fluorescence intensity was significantly better at pH 7 (4.2 x 105 cps; P-value < 0.01) than at acid or alkaline conditions. GFP is a good biomarker for environments near netural conditions: however, GFP may be unsuitable where soils or waters are below or above pH 7 because of loss in fluorescence intensity. Alternative fluorescent markers and delivery systems must be examined in different environments to optimize responses from bioreporter molecules.     

A simple method for estimating dermal absorption of chemicals in water

A semiempirical mathematical model is proposed for estimating the dermal absorption of chemicals from dilute aqueous solutions, such as bath water. Absorption depends on the concentration of the chemical in water, the area of skin exposed, the time of exposure, and a permeation coefficient that depends importantly on the relative solubility of the material in lipids and water, among other factors not so easily modeled.