Characteristics of major secondary ions in typical polluted atmospheric aerosols during autumn in central Taiwan

In autumn of 2008, the chemical characteristics of major secondary ionic aerosols at a suburban site in central Taiwan were measured during an annually occurring season of high pollution. The semicontinuous measurement system measured major soluble inorganic species, including NH(4)(+), NO(3)(-), and SO(4)(2-), in PM(10) with a 15 min resolution time. The atmospheric conditions, except for the influences of typhoons, were dominated by the local sea-land breeze with clear diurnal variations of meteorological parameters and air pollutant concentrations. To evaluate secondary aerosol formation at different ozone levels, daily ozone maximum concentration (O(3,daily max)) was used as an index of photochemical activity for dividing between the heavily polluted period (O(3,daily max) ≧80 ppb) and the lightly polluted period (O(3,daily max)<80 ppb). The concentrations of PM(10), NO(3)(-), SO(4)(2-), NH(4)(+) and total major ions during the heavily polluted period were 1.6, 1.9, 2.4, 2.7 and 2.3 times the concentrations during the lightly polluted period, respectively. Results showed that the daily maximum concentrations of PM(10) occurred around midnight and the daily maximum ozone concentration occurred during daytime. The average concentration of SO(2) was higher during daytime, which could be explained by the transportation of coastal industry emissions to the sampling site. In contrast, the high concentration of NO(2) at night was due to the land breeze flow that transport inland urban air masses toward this site. The simulations of breeze circulations and transitions were reflected in transports and distributions of these pollutants. During heavily polluted periods, NO(3)(-) and NH(4)(+) showed a clear diurnal variations with lower concentrations after midday, possibly due to the thermal volatilization of NH(4)NO(3) during daytime and transport of inland urban plume at night. The diurnal variation of PM(10) showed the similar pattern to that of NO(3)(-) and NH(4)(+) aerosols. This indicated that the formatted secondary aerosols in the inland urban area could be transported to the coastal area by the weak land breeze and deteriorated the air quality in the coastal area at night.     

多相催化臭氧氧化技术机理研究进展

多相催化臭氧氧化技术能够有效去除水中的微量有机物。尽管有越来越多的研究致力于多相催化臭氧氧化技术领域,以及各种新的催化剂的引入,但对于多相催化臭氧氧化技术机理尚不清楚。因此,本文针对多相催化臭氧氧化技术中常用的负载型金属、负载型金属氧化物以及活性炭三类催化剂的反应机理进行了探讨。此外还对机理研究中存在的问题进行了探讨。     

消防水幕对有害气体阻隔效果的试验研究

为研究消防水幕对有害气体的阻隔效果,通过大型和小型2种尺度的试验,测定大型真实水幕对液化石油气的阻隔效果,并建立实验室小尺寸水幕模型,测定水幕对液化石油气、氯气、氨气、二氧化碳等气体的阻隔效果。此外,在小尺寸模型中,添加特定化学药剂测定水幕对氨气和氯气的阻隔效果。结果表明:消防水幕可以有效地阻隔和稀释有害气体;在水源中添加特定的化学药剂,可以有效地提高水幕阻隔和稀释的效果,阻隔效率达到90%以上。为消防部队今后处置化学事故提供切实可靠的数据支撑。     

某桥墩承台病害分析与处理

桥墩病害的正确分析处理,事关桥梁的安危。介绍了某桥墩承台病害,分析了产生病害的主要原因是混凝土碱骨料反应。据碱骨料反应产生的条件,提出了桥墩承台病害采用优料加大截面隔绝法的处理方案,经由实施,使桥梁重获新生。所提桥墩承台病害处理方案正确,处理效果良好,对类似桥墩的分析处理具借鉴意义。     

Quantitative analysis of microbial biomass yield in aerobic bioreactor

We have studied the integrated model of reaction rate equations with thermal energy balance in aerobic bioreactor for food waste decomposition and showed that the integrated model has the capability both of monitoring microbial activity in real time and of analyzing biodegradation kinetics and thermal-hydrodynamic properties. On the other hand, concerning microbial metabolism, it was known that balancing catabolic reactions with anabolic reactions in terms of energy and electron flow provides stoichiometric metabolic reactions and enables the estimation of microbial biomass yield (stoichiometric reaction model). We have studied a method for estimating real-time microbial biomass yield in the bioreactor during food waste decomposition by combining the integrated model with the stoichiometric reaction model. As a result, it was found that the time course of microbial biomass yield in the bioreactor during decomposition can be evaluated using the operational data of the bioreactor (weight of input food waste and bed temperature) by the combined model. The combined model can be applied to manage a food waste decomposition not only for controlling system operation to keep microbial activity stable, but also for producing value-added products such as compost on optimum condition.     

连续搅拌釜式反应器放热反应失控事故预防

运用敏感度方法研究连续搅拌釜式反应器(CSTR)放热反应的参数敏感性行为及规律,探讨CSTR反应器的安全操作区域和敏感操作区域。研究发现:无因次活化能小于4的反应系统,其整个操作参数空间都是安全的;无因次活化能大于4的反应系统,只有选择无因次活化能小于其临界值,反应系统才能安全、稳定地运行;临界无因次反应热的值与无因次丹克莱尔数和无因次反应热有关;丹克莱尔数和无因次反应热越大,则临界无因次反应热越小,安全操作区域也越小。     

Development of non-invasive fetal DNA diagnosis from maternal blood

Several attempts have been made to detect and retrieve fetal nucleated cells including nucleated erythrocytes (NRBCs), leukocytes, and trophoblasts in maternal blood. We have recently developed a new method for non-invasive fetal DNA diagnosis from maternal blood. Peripheral blood granulocytes including NRBCs were isolated by a discontinuous density gradient method using Percoll (Pharmasia). NRBCs were found and retrieved at a single cell level using a micromanipulator under a microscope. To determine whether the origin of the NRBCs was maternal or fetal, the NRBCs were analysed by polymerase chain reaction (PCR) amplification to determine the presence of a Y-chromosome-specific repeat sequence in mothers carrying male fetuses. We were successful in predicting fetal sex accurately in 10 out of 11 samples taken from maternal blood. This new technique opens up fetal DNA diagnosis from maternal blood during the first trimester of pregnancy to the whole population because there is no risk to the fetus or the mother.     

高温吸收剂喷射对尘粒性质的影响

本文综述了现有的高温吸收剂喷射对粒子性质影响的研究成果．总结了现有的有关高温吸收剂喷射对尘粒的比电阻、粒子分布、粒子结构形态的影响以及由此产生的对除尘器性能的影响．     

C2H6/CO2组分构成对瓦斯着火延迟时间的影响规律研究

为进一步研究多种不同性质的气体对瓦斯着火过程的影响,采用CHEMKIN-PRO Release软件,选择CH_4燃烧化学反应机理USC Mech 2.0模型对不同组分构成的C_2H_6/CO_2与甲烷混合气体进行数值模拟,然后分析不同组分下瓦斯着火延迟时间的变化趋势,并利用SENKIN程序对其进行敏感性分析。计算结果表明:当C_2H_6百分比小于CO_2百分比时,随着CO_2百分比的增加,瓦斯着火延迟时间略有增加,且其在T=1200K下延长了17.0%,在T=2200K下延长了8.4%,同时抑制CH_4生成的关键反应步敏感性系数下降幅度略大,其协同抑制瓦斯爆炸;当C_2H_6百分比大于CO_2百分比时,随着C_2H_6百分比的增加,瓦斯着火延迟时间大幅缩短,且其在T=1200K下缩短了63.7%,在T=2200K下缩短了35.5%,同时促进CH_4生成的关键反应步敏感性系数下降幅度大,其协同促进瓦斯爆炸。     

Functional relationship between ammonia-oxidizing bacteria and ammonia-oxidizing archaea populations in the secondary treatment system of a full-scale municipal wastewater treatment plant

The abundance of ammonia-oxidizing bacteria and archaea and their amoA genes from the aerobic activated sludge tanks, recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant (WWTP) was determined. Polymerase chain reaction and denaturing gradient gel electrophoresis were used to generate diversity profiles, which showed that each population had a consistent profile although the abundance of individual members varied. In the aerobic tanks, the ammonia-oxidizing bacterial (AOB) population was more than 350 times more abundant than the ammonia-oxidizing archaeal (AOA) population, however in the digesters, the AOA population was more than 10 times more abundant. Measuring the activity of the amoA gene expression of the two populations using RT-PCR also showed that the AOA amoA gene was more active in the digesters than in the activated sludge tanks. Using batch reactors and ddPCR, amoA activity could be measured and it was found that when the AOB amoA activity was inhibited in the anoxic reactors, the expression of the AOA amoA gene increased fourfold. This suggests that these two populations may have a cooperative relationship for the oxidation of ammonia.