This critical review highlights recent advances in the structurally modified (thio)urea-based receptors for anion complexation and sensing. Modifications of the (thio)urea structure are aimed at a better anion binding in terms of higher binding constant, anion selectivity and feasibility. Major (thio)urea receptors are reviewed as N-alkyl, N-aryl and N-amido/N-amino (thio)ureas. Hints for designing (thio)urea-based receptors for anions are discussed (102 references).
Nitrous acid (HONO) is a major precursor of tropospheric hydroxyl radical (OH) that accelerates the formation of secondary pollutants. The HONO sources, however, are not well understood, especially in polluted areas. Based on a comprehensive winter field campaign conducted at a rural site of the North China Plain, a box model (MCM v3.3.1) was used to simulate the daytime HONO budget and nitrate formation. We found that HONO photolysis acted as the dominant source for primary OH with a contribution of more than 92%. The observed daytime HONO could be well explained by the known sources in the model. The heterogeneous conversion of NO2 on ground surfaces and the homogeneous reaction of NO with OH were the dominant HONO sources with contributions of more than 36% and 34% to daytime HONO, respectively. The contribution from the photolysis of particle nitrate and the reactions of NO2 on aerosol surfaces were found to be negligible in clean periods (2%) and slightly higher during polluted periods (8%). The relatively high OH levels due to fast HONO photolysis at the rural site remarkably accelerated gas-phase reactions, resulting in the fast formation of nitrate as well as other secondary pollutants in the daytime.
Halogen atoms affect the budget of ozone and the fate of pollutants such as hydrocarbons and mercury. Yet their sources and significances in polluted continental regions are poorly understood. Here we report the observation of unprecedented levels (averaging to 60 parts per trillion) of bromine chloride (BrCl) at a mid-latitude site in North China during winter. Widespread coal burning in rural households and a photo-assisted process were the primary source of BrCl and other bromine gases. BrCl contributed about 55% of both bromine (Br) and chlorine (Cl) atoms. The halogen atoms increased the abundance of ‘conventional’ tropospheric oxidants (OH, HO2, and RO2) by 26–73%, and enhanced oxidation of hydrocarbon by nearly a factor of two and the net ozone production by 55%. Our study reveals the significant role of reactive halogen in winter atmospheric chemistry and the deterioration of air quality in continental regions where uncontrolled coal combustion is prevalent.
SUMMARY:The regulatory mechanism of miRNA induction in response to Mycobacterium tuberculosis (MTB) infection has not been clearly established. Autophagy has recently been identified as an effective way to control intracellular survival of MTB. In the present study, we demonstrate a novel role of miR-30A in the negative regulation of the autophagy-mediated anti-MTB response. We found that overexpression of miR-30A suppresses the elimination of intracellular MTB through the inhibition of autophagy. Furthermore, there was a negative correlation between concentrations of miR-30A and beclin-1 in MTB positive patients and miR-30A expression decreased after anti-TB treatment. Our results indicate that miR-30A plays a key role in immune response against MTB and, therefore, may serve as a potential target for future treatments of tuberculosis infection.
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