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Enhanced secondary organic aerosol formation during dust episodes by photochemical reactions in the winter in Wuhan

Journal of Environmental Sciences 2023年第11期133卷 70-82页

作者： Kai Xu Yafei Liu Chenlu Li Chen Zhang Xingang Liu Qijie Li Min Xiong Yujun Zhang Shijie Yin Yu Ding State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China Wuhan Municipality Environmental Monitoring Center Wuhan 430015China College of Environment and Ecology Chongqing UniversityChongqing 400030China

To investigate the effect of frequently occurring mineral dust on the formation of secondary organic aerosol(SOA),106 volatile organic compounds(VOCs),trace gas pollutants and chemical components of PM_(2.5) were measured continuously in January 2021 in Wuhan,Central China.The observation period was divided into two stages that included a haze period and a following dust period,based on the ratio of PM_(2.5) and PM_(10) concentrations.The average ratio of secondary organic carbon(SOC)to elemental carbon(EC)was 1.98 during the dust period,which was higher than that during the haze period(0.69).The contribution of SOA to PM_(2.5) also increased from 2.75% to 8.64%.The analysis of the relationships between the SOA and relative humidity(RH)and the odd oxygen(e.g.,O_(X)=O_(3)+NO_(2))levels suggested that photochemical reactions played a more important role in the enhancement of SOA production during the dust period than the aqueous-phase reactions.The heterogeneous photochemical production of OH radicals in the presence of metal oxides during the dust period was believed to be enhanced.Meanwhile,the ratios of trans-2-butene to cis-2-butene and m-/p-xylene to ethylbenzene(X/E)dropped significantly,confirming that stronger photochemical reactions occurred and SOA precursors formed efficiently.These results verified the laboratory findings that metal oxides in mineral dust could catalyse the oxidation of VOCs and induce higher SOA production.

关键词： VOCs Mineral dust Metal oxides SOA photochemical reactions

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photochemical reactions of Microcystin-LR Following Irradiation with UV Light

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Open Journal of Physical Chemistry 2016年第4期6卷 79-85页

作者： Yoshihiro Mizukami Faculty of Liberal Arts and Education Shiga University Otsu Japan

photochemical reactions of microcystin-LR, a toxic compound produced by some blue green algae, were investigated. Ultraviolet absorption of microcystin-LR was assessed. Time-dependent density functional theory (TDDFT) calculations indicated that absorption peak at 238 nm was mainly due to excitation of electrons from the linear chain structure Adda of microcystin-LR. Irradiation of microcystin-LR with UV light resulted in the reduction of the 238 nm absorption peak and the appearance of a new peak at 300 nm. Density functional theory (DFT) and TDDFT calculations with a model molecule suggested that this 300 nm peak was due to tricyclo-Adda microcystin-LR, an intermediate in photochemical reactions of microcystin-LR. Analysis of the rate of this photochemical reaction showed that it was a first order reaction.

关键词： Microcystin-LR UV Irradiation UV Spectra DFT Calculations photochemical reactions

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Multiple Resonance Thermally Activated Delayed Fluorescence Sensitizers Enable Green-toUltraviolet Photon Upconversion:Application in photochemical Transformations

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CCS Chemistry 2022年第12期4卷 3852-3863页

作者： Yaxiong Wei Ke Pan Xiaosong Cao Yuanming Li Xiaoguo Zhou Chuluo Yang Shenzhen Key Laboratory of Polymer Science and Technology College of Materials Science and EngineeringShenzhen UniversityShenzhen 518060 School of Physics and Electronic Information Anhui Normal UniversityWuhuAnhui 241000 Department of Chemical Physics University of Science and Technology of ChinaHefeiAnhui 230026

Efficient visible-to-ultraviolet(UV)triplet-triplet annihilation upconversion(TTA-UC)with large anti-Stokes shift is highly promising for solar-powered and indoor applications.Nonetheless,the excitationwavelengthis confined to the blue region(reactions even under excitation of low-power-density green light-emitting diode light,revealing the broad utility of thesemolecular upconverters.This work unlocks the huge potential of MR-TADF-type sensitizers in upconversion applications.

关键词： triplet-triplet annihilation upconversion visible-to-ultraviolet upconversion multiple resonance photochemical reactions

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Ambient levels of atmospheric carbonyls in Beijing during the 2008 Olympic Games

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Journal of Environmental Sciences 2010年第9期22卷 1348-1356页

作者： Zhu Xu Junfeng Liu Yujie Zhang Peng Liang Yujing Mu Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Graduate School of Chinese Academy of Sciences Beijing 100039 China

The measurements of atmospheric carbonyls concentrations in Beijing were conducted from 12 July to 8 October, 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. Six carbonyls, including formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, and hexaldehyde, were identified in all air samples. The total average concentrations of these carbonyls before, during, and after traffic restriction were （48.1 ± 15.2）, （36.6 ± 14.5） and （23.4± 12.3） μg/m^3, respectively. Compared with the period after traffic restriction, the distinct high concentrations of the carbonyls before and during traffic restriction were primarily ascribed to the remarkable contribution of photochemical reactions. With respect to our previous investigation in the summer of 2005, the reductions of formaldehyde, acetaldehyde and acetone during traffic restriction period were about 64%, 47% and 27%, respectively, indicating that the air cleaning actions adopted by the Chinese government for the two games were efficient. The lowest levels of atmospheric carbonyls and the extremely high composition proportion of acetone after the traffic restriction were mainly attributed to the long-term effect of the control measures for the two games.

关键词： Olympic Games Paralympic Games carbonyl compounds traffic restriction photochemical reactions vehicular exhaust

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An updated overview on the development of new photosensitizers for anticancer photodynamic therapy

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Acta Pharmaceutica Sinica B 2018年第2期8卷 137-146页

作者： Juan Zhang Chengshi Jiang Joao Paulo Figueiró Longo Ricardo Bentes Azevedo Hua Zhang Luis Alexandre Muehlmann School of Biological Science and Technology University of Jinan Institute of Biological Sciences University of Brasilia Faculty of Ceilandia University of Brasilia

Photodynamic therapy(PDT), based on the photoactivation of photosensitizers(PSs), has become a well-studied therapy for cancer. Photofrin~?, belonging to the first generation of PS, is still widely used for the treatment of different kinds of cancers; however, it has several drawbacks that significantly limit its general clinical use. Consequently, there has been extensive research on the design of PS molecules with optimized pharmaceutical properties, with aiming of overcoming the disadvantages of traditional PS, such as poor chemical purity, long half-life, excessive accumulation into the skin, and low attenuation coefficients. The rational design of novel PS with desirable properties has attracted considerable research in the pharmaceutical field. This review presents an overview on the classical photosensitizers and the most significant recent advances in the development of PS with regard to their potential application in oncology.

关键词： Anti-cancer Photosensitizers Photodynamic therapy photochemical reactions Oncology BODIPY

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ACTIVE INTERMEDIATES IN PHOTORADICAL AGING OF POLYMERS

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Chinese Journal of Polymer Science 2001年第2期19卷 167-173页

作者： M.Ya.Mel’nikov Department of Chemistry M. V.Lomonosov Moscow State University Moscow 119899 Russia

The data referring to the mechanism and efficiency of electronically excited macroradical and radical anionreactions, the important role of photochemical chain reactions in polymers are presented, It was found that by varying photonenergy, temperature, photolysis time and competition between thermal and photochemical reactions, it is possible to change the functional composition and molecular weight distribution of polymers.

关键词： Macroradicals Radical anions photochemical reactions Aging

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Nitrogen Dioxide and Ozone Pollution in the Chicago Metropolitan Area

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Journal of Environmental Protection 2020年第8期11卷 551-569页

作者： Zixian Wang Jennifer L. Anthony Larry E. Erickson Michael J. Higgins Gregory L. Newmark Tim Taylor Department of Chemical Engineering Kansas State University Manhattan KS USA Department of Statistics Kansas State University Manhattan KS USA Department of Landscape Architecture/Regional and Community Planning Kansas State University Manhattan KS USA

Ground-level ozone is a harmful air pollutant associated with several health issues. Ozone concentrations have exceeded the National Ambient Air Quality Standards (NAAQS) in the Chicago metropolitan area on hot summer days for many years because of nitrogen oxide and volatile organic compound emissions. Annual fourth highest 8-hour ozone concentrations have been between 0.070 and 0.084 ppm at several monitoring sites in Cook county, during the 2016-2018 time period. The continuous measurement of nitrogen dioxide (NO2) and ozone (O3) was conducted in several communities in Chicago in 2017. The air pollution impacts the health of all who live in the area. The data were used to analyze correlations between the O3 distribution and its association with ambient concentrations of NO2 from transportation emissions. Higher concentrations in NO2 and O3 occurred in succession in the daytime. The diurnal variation of O3 concentration was analyzed. The daily cycle of NO2 concentration reaches a maximum in the late morning and has smaller nighttime concentrations. The daily cycle of ozone concentration reaches the maximum in the afternoon and also becomes smaller for nighttime concentrations. In addition, relationships were found between O3 and NO2. Monthly variations of ozone and NO2 are presented. Some options to reduce ozone pollution are presented.

关键词： Volatile Organic Compounds Health Vehicle Emissions Daily Transient Cycles Ozone Precursors photochemical reactions

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