Fluorescent sensors are attractive and versatile tools for both chemical sensing and biological imaging. Herein, a novel pyrene derivative fluorophore, Py-Cy, possessing the monomer/excimer conversion feature, was synthesized; and the design rationale for this fluorophore is combination of extending conjugation length and incorporating donor-π-acceptor structure. The positively charged Py-Cy shows quite good water solubility and exhibits absorption in the visible-light range, and its monomer and excimer emit red light and near-infrared light respectively, which is extremely beneficial for biosensing or bioimaging. To explore the potential utilization of this new fluorophore, we choose hypochlorite as a model analyte, which can break the double bond in the molecular structure, thereby generating the water-insoluble pyrenecarboxaldehyde; this process correspondingly leads to fluorescence changes and thus affords the ratiometric fluorescent detection of hypochlorite in real samples and cell imaging. The approach offers new insights for designing other fluorophores which emit red or near-infrared light and for devising technically simple ratiometric fluorescent sensors.

Mono- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans (mono- to octa-CDD/Fs) were determined in 14 stack gas samples from two municipal solid waste incinerators and two medical waste incinerators. The total PCDD/F concentrations were 5.1-390 ng/Nm(3), and the mono- to trichlorinated homologues contributed 53.2-94.5% of the total concentrations. The homologue profiles were dominated by the MoCDF, ranged from 1.51 to 113.1 ng/Nm(3), and the proportion that each PCDF homologue group contributed to the total concentration decreased with increasing chlorination level. The toxic equivalent concentrations (I-TEQs) were 0.01-2.81 ng I-TEQ/Nm(3), with 2,3,4,7,8-PeCDF being the biggest contributor, at 30.6-60.0%. Correlations were found among the PCDD/PCDF ratios (D/F ratios), the degree of chlorination, and the TEQ. Stack gases with low I-TEQs had higher proportions of the less chlorinated homologues and lower D/F ratios, which could be attributed to the removal of the more chlorinated isomers by the air pollution control systems used by the incinerators. 2,8-DiCDF, 2,4,8-TrCDF, DiCDF, and TrCDF can be used as TEQ indicators for monitoring PCDD/Fs. 2,8-DiCDF and 2,4,8-TrCDF correlated well with the TEQ because they strongly correlated with 2,3,4,7,8-PeCDF, implying possible correlations in their formation mechanisms.

An AIE-based fluorescent test strip (OPD-TPE-Py-2CN) for rapid and sensitive detection of gaseous phosgene was designed. The fluorescence changes from blue to green upon exposure to phosgene. And the detection limit (1.87 ppm) is lower than the "harmless" level of human response to acute phosgene exposure.

A ratiometric fluorescent system for CaE detection with AIE dots as the FRET donors was designed. Upon enzymatic reaction, electrostatic interaction between the cationic TPE-N(+) dots and the enzymatic reaction product - the negatively charged fluorescein molecules - allows the FRET process to proceed, thus affording the ratiometric fluorescence CaE assay.

Large amounts of heavy metals discharged by industrial cities that are located along the middle reach of Yellow River, China have detrimental impacts on both the ecological environment and human health. In this study, fourteen surface sediment samples were taken in the middle reach of the Yellow River. Contents of Zn, Pb, Ni, Cu, Cr, Cd, As were measured, and the pollution status was assessed using three widely used pollution assessment methods, including the single factor index method, Nemerow pollution index method and potential ecological risk index. The concentrations of the studied heavy metals

h i g h l i g h t sPCDD/Fs, PCBs, HxCBz, PeCBz and polychlorophenols in 2,4-D were analyzed. Relationship between the precursors and UPPOPs was discussed. Emissions of PCDD/Fs and dl-PCBs in China were evaluated. A suggestion on 2,4-D production was developed to reduce UPPOPs emission. a r t i c l e i n f o

Eight important heavy metals (As, Cr, Cu, Ni, Pb, Zn, Mn, and Hg) were investigated in surface soil samples collected from the Lhasa-Shigatse-Nam Co region, Tibetan Plateau, China. The mean contents of As, Cr, Cu, Ni, Pb, Zn, Mn, and Hg in the samples were 39.5, 57.4, 28.5, 48.2, 15.7, 79.2, 637 and 0.0175 mg/kg, respectively. All metals were divided into three clusters by cluster analysis. The results of geoaccumulation index indicated that no samples were polluted by Cr, Pb, Zn, and Mn, and samples were polluted with As, Cu, Ni, and Hg to different degrees. All surface soils had a low ecological risk with potential ecological risk index below 150, indicating a low ecological risk. As, Pb, and Hg were the primary contributors to potential ecological risk.

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