The Ring-Opening Reaction of 7,7’-Dimethyl-2, 5-bis(trimethylsilyl)-dithieno[2,3-b:3’,2’-d]silole in the Presence of NXS (X = Cl, Br, I)

In this paper, the synthetic method for making 7,7’-dimethyl-2,5-bis(trimethylsilyl)-dithieno[2,3-b:3’,2’-d] silole (1) was developed by using 2,2’-dibromo-5,5’-bis-trimethyl-silanyl[3,3’]bithiophenyl as starting material in one pot reaction. In the presence of NXS (X = Cl, Br, I), a novel ring-opening reation was occurred on the silole ring of 1 in DMF or THF. By using such kind of reaction, two types of ring opened products, (2’-halo-5,5’-bis(trimethylsilanyl)[3,3’]bithiophenyl-2-yl)-dimethylsilanols and 2,2’-dihalo-5,5’-bis(trimethylsi- lanyl)[3,3’]bithiophenyls were obtained efficiently.

Quantifying the contribution of activity patterns to PM_(2.5)exposure inequity between urban and rural residents by a novel method

PM_(2.5)pollution variations in different microenvironments would result in PM_(2.5)exposure inequity between rural and urban residents.In this study,the real-time PM_(2.5)exposure of urban and rural residents in China was examined based on portable PM_(2.5)sensors together with activity patterns derived from questionnaire surveys,with a focus on students and senior citizens who are sensitive to air pollution.The results showed that PM_(2.5)exposure varied significantly among different resident groups,with higher PM_(2.5)exposure of rural residents than those of urban residents.PM_(2.5)exposure peaks mostly occurred during(Accompanied)cooking activities owing to strong emissions.Sleeping and resting were the main activities that affected PM_(2.5)exposures of different resident groups,accounting for 60.7%-94.5%of total daily exposures.Furthermore,the long duration of sleeping makes it the predominant activity contributing to PM 25 exposure inequity.It is necessary to obtain point-to-point respiratory volume(respiratory rate)data when measuring real-time PM_(2.5)exposure data and incorporate respiratory volume(respiratory rate)into the analysis of PM_(2.5)exposure.For the first time,this study quantified the PM_(2.5)exposure inequality based on a novel method and can provide useful information for further studies on the exposure inequity.

Characteristics of chemical components in PM2.5 at a plateau city, South-west China

A sampling campaign including summer, autumn and winter of 2014 and spring of 2015 was accomplished to obtain the characteristic of chemical components in PM2.5 at three sites ofKunming, a plateau city in South-west China. Nine kinds of water-soluble inorganic ions （WSI）, organic and element carbon （OC and EC） in PM2.5 were analyzed by ion chromatography and thermal optical reflectance method, respectively. Results showed that the average concentrations of total WSI, OC and EC were 22.85±10.95 μg.m -3, 17.83±9.57 μg.m-3 and 5.114-4.29 μg.m-3, respectively. They totally accounted for 53.0% of PM2.5. Secondary organic and inorganic aerosols （SOA and SIA） were also assessed by the minimum ratio of OC/EC, nitrogen and sulfur oxidation ratios. The annual average concentrations of SOA and SIA totally accounted for 28.3% of the PM2.5 concentration. The low proportion suggested the primary emission was the main source of PM2.5 in Kunming. However, secondary pollution in the plateau city should also not be ignorable, due to the appropriate temperature and strong solar radiation, which can promote the atmospheric photochemical reactions.

Particle-bound polycyclic aromatic hydrocarbons in typical urban of Yunnan-Guizhou Plateau:Characterization,sources and risk assessment

Monthly particle-phase ambient samples collected at six sampling locations in Yuxi,a high-altitude city on the edge of Southeast Asia,were measured for particle-associated PAHs.As trace substances,polycyclic aromatic hydrocarbons(PAHs)are susceptible to the influences of meteorological conditions,emissions,and gas-particulate partitioning and it is challenging job to precise quantify the source and define the transmission path.The daily concentrations of total PM_(2.5)-bound PAHs ranged from 0.65 to 80.76 ng/m^(3),with an annual mean of 11.94 ng/m^(3).Here,we found that the concentration of PM_(2.5)-bound PAHs in winter was significantly higher than that in summer,which was mainly due to source and meteorology influence.The increase of fossil combustion and biomass burning in cold season became the main contributors of PAHs,while precipitation and low temperature exacerbated this difference.According to the concentration variation trend of PM_(2.5)-bound PAHs and their relationship with meteorological conditions,a new grouping of PAHs is applied,which suggested that PAHs have different environmental fates and migration paths.A combination of source analysis and trajectory model supported local sources from combustion of fossil fuel and vehicle exhaust contributed to the major portion on PAHs in particle,but on the Indochina Peninsula the large number of pollutants emitted by biomass burning during the fire season would affect the composition of PAHs through long-range transporting.Risk assessment in spatial and temporal variability suggested that citizens living in industrial areas were higher health risk caused by exposure the PM_(2.5)-bound PAHs than that in other regions,and the risk in winter was three times than in summer.