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641.
煤制甲醇厂的循环冷却水系统中因轻微泄漏出现泡沫和微小块状污垢,取样后通过光学显微观察、扫描电镜和化学显色分析表明,该污垢主要为细菌纤维素,并采用微生物学分离手段获得1株优势菌。经16S rDNA基因序列及BIOLOG碳源利用分析表明,该菌为木葡糖酸醋杆菌(Gluconacetobacter xylinus)。甲醇浓度和pH值对该菌产纤维素能力影响较大,甲醇浓度为15~25 mL/L时产纤维素最强,pH值为8~9时纤维素产量仅为pH值5.0时的50%。当与其他甲醇降解菌共同生长时,由于竞争性排除、生态位争夺等作用,该菌产纤维素能力下降超过37.9%。该发现为生物法控制煤制甲醇循环冷却水系统中的纤维素污垢提供科学依据。 相似文献
642.
Jianrui Niu Haobin Liu Hengli Qian Jie Liu Mengyuan M Erhong Duan Lei Yu 《环境科学学报(英文版)》2020,32(2):260-272
In order to study their synergistic catalytic effects in toluene degradation, CuMn_2O_4/HTS-1(HTS-1 was a titanium silicon molecular sieve), Cu_(0.7)Mn_2Y_(0.3)O_x/HTS-1 and Cu_(0.7)Mn_2Ce_(0.3)O_x/HTS-1 catalysts were prepared by the impregnation method.The textural properties, redox properties and acidity of the catalysts were characterized by X-ray diffractometer(XRD),transmission electron microscopy(TEM), scanning electron microscopy(SEM), H_2 temperature-programmed reduction(H_2-TPR), X-ray photoelectron spectroscopy(XPS),frustrated total internal reflection(FT-IR), ammonium temperature-programmed desorption(NH_3-TPD) and pyridine adsorption internal reflection(Py-IR) measurements.The potential roles of Lewis acid sites(activating dioxygen) were discussed, and the experimental results indicated that the most efficient route for toluene degradation over Cu_(0.7)Mn_2Ce_(0.3)O_x/HTS-1(toluene conversion rate of 90%(T99) = 295℃) was ascribed to regulation of the synergistic effects of redox properties(activating molecular toluene) and Lewis acid sites(activating dioxygen).The Mars–Van–Krevelen(MVK) model was adopted to describe the reaction process of toluene oxidation, which gave an in-depth view into the toluene degradation over CuMn_2O_4/HTS-1, Cu_(0.7)Mn_2Y_(0.3)O_x/HTS-1 and Cu_(0.7)Mn_2Ce_(0.3)O_x/HTS-1.In addition, the synergistic effects between redox properties and Lewis acid sites were studied in detail. 相似文献
643.
Shan Dan Wei Wang Jinghui Ren Yali Li Hua Hu Zhengfeng Xu Tze Kin Lau Jianhong Xie Weihua Zhao Hefeng Huang Jiansheng Xie Luming Sun Xiaohong Zhang Weipeng Wang Shixiu Liao Rong Qiang Jiangxia Cao Qiufang Zhang Yulin Zhou Haiyan Zhu Mei Zhong Yi Guo Linhua Lin Zhiying Gao Hong Yao Hongyun Zhang Lijian Zhao Fuman Jiang Fang Chen Hui Jiang Songgang Li Yingrui Li Jun Wang Jian Wang Tao Duan Yue Su Xiuqing Zhang 《黑龙江环境通报》2012,32(13):1225-1232
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646.
Duan Lei Yang Xiaohan Xie Jia Zhan Wenli Zhang Changbin Liu Hong Wei Mengru Tang Yuan Zhao Hongyu Luo Mingyong 《Food and environmental virology》2021,13(3):357-367
Food and Environmental Virology - Norovirus, the leading cause of non-bacterial acute gastroenteritis (AGE) worldwide, is constantly mutating. Continuous monitoring of the evolution of epidemic... 相似文献
647.
Air pollution and its control in China 总被引:2,自引:0,他引:2
Hao Jiming He Kebin Duan Lei Li Junhua Wang Litao 《Frontiers of Environmental Science & Engineering in China》2007,1(2):129-142
The rapid growth of China’s economy has led to severe air pollution characterized by acid rain, severe pollution in cities,
and regional air pollution. High concentrations are found for various pollutants such as sulfur dioxides (SO2), nitrogen oxides (NOx), and fine particulates. Great efforts have thus been undertaken for the control of air pollution in the country. This paper
discusses the development and application of appropriate technologies for reducing the major pollutants produced by coal and
vehicles, and investigates air quality modeling as an important support for policy-making. 相似文献
648.
An environmental impact assessment (EIA) system was established in 1979 in China. Although EIA was designed as a tool for pollution prevention, in practice it has been based on end-of-pipe (EOP) treatment control since it was first introduced. This approach has ensured an overwhelming focus by enterprises on the use of EOP treatment, rather than pollution prevention, to meet environmental standards, and it has produced a low rate of operation for EOP facilities. The low operation rate for EOP facilities can be traced to the traditional EIA system: it leads project proponents to develop large EOP treatment facilities, but once the main production lines are put into operation, proponents rarely have sufficient funds to operate the treatment facilities. This paper analyzes problems that exist in the EIA system in China, and it describes the Cleaner Production Index and Evaluation System, which is being proposed by environmental authorities in China to evaluate EIA projects based on cleaner production criteria. The paper also suggests how cleaner production analysis can be integrated into the EIA system to improve it. 相似文献
649.
Objective: Imitation of risky behaviors among drivers is a potentially dangerous threat to driving safety but is infrequently discussed in the existing literature. To enrich the understanding of drivers' imitation behaviors on the road, 2 experiments were designed for a simulated traffic environment. Methods: Safe and risky behaviors were demonstrated by model vehicles separately in the 2 experiments, and imitation behaviors of the participants were observed and analyzed. Results: From experiment 1 it was found that the following distance of participants (measured in time headway) was affected by the distance demonstrated by other vehicles on the road. The influence was stronger when the speed was low, and the participants imitated both risky and safe behavior models. When the speed was high, the participants tended to only learn safe behaviors. In experiment 2, when approaching yellow lights, it was examined whether a driver's decision (pass or stop) would be affected by the behavior of another vehicle (the model vehicle), which was designed to either pass through or stop at the intersection. When the model vehicle ran the yellow light, 65 percent of the participants did the same, even though they were 30?m behind the model vehicle. In contrast, if the model vehicle stopped at the intersection, only 25 percent of the participants decided to pass. Conclusions: It was found that both novice and experienced participants had the tendency to imitate what they saw but were rarely aware of the influence by other drivers in both scenarios. 相似文献
650.
Hengyi DUAN Xiaotu LIU Meilin YAN Yatao WU Zhaorong LIU 《Frontiers of Environmental Science & Engineering》2016,10(1):73-84
Volatile organic compounds (VOCs) and carbonyl compounds were measured both indoors and outdoors in 50 residences of Beijing in heating (December, 2011) and non-heating seasons (April/May, 2012). SUMMA canisters for VOCs and diffusive samplers for carbonyl compounds were deployed for 24 h at each site, and 94 compounds were quantified. Formaldehyde, acetone and acetaldehyde were the most abundant carbonyl compounds both indoors and outdoors with indoor median concentrations being 32.1, 21.7 and 15.3 μg·m−3, respectively. Ethane (17.6 μg·m−3), toluene (14.4 μg·m−3), propane (11.2 μg·m−3), ethene (8.40 μg·m−3), n-butane (6.87 μg·m−3), and benzene (5.95 μg·m−3) showed the high median concentrations in indoor air. Dichloromethane, p-dichlorobenzene (p-DCB) and toluene exhibited extremely high levels in some residences, which were related with a number of indoor emission sources. Moreover, isoprene, p-dichlorobenzene and carbonyls showed median indoor/outdoor (I/O) ratios larger than 3, indicating their indoor sources were prevailing. Chlorinated compounds like CFCs were mainly from outdoor sources for their I/O ratios being less than 1. In addition, indoor concentrations between two sampling seasons varied with different compounds. Carbonyl compounds and some chlorinated compounds had higher concentrations in the non-heating season, while alkanes, alkenes, aromatic compounds showed an increase in the heating season. Indoor concentration of VOCs and carbonyls were influenced by locations, interior decorations and indoor activities, however the specific sources for indoor VOCs and carbonyls could not be easily identified. The findings obtained in this study would significantly enhance our understandings on the prevalent and abundant species of VOCs as well as their concentrations and sources in Beijing residences. 相似文献