[Microplastic Characteristics and Risk Assessment in Multigate Dam-type River].

Microplastics pose a serious ecological threat to rivers in China, and the construction of a large number of dams has complicated this problem. Ten dams of the Shaying River were chosen to investigate the abundance and composition of microplastics in surface water and sediments of the reservoir and upstream river. Ecological risk was evaluated using species sensitive distribution （SSD） and pollution load index （PLI）. The results showed that the Shaying River was exposed to a severe risk of microplastics from upstream to downstream. The construction of dams did not significantly affect the distribution of microplastics in the river. River sediments became a sink for microplastics in the surface water； however, the ecological risk posed by microplastics in the surface water was greater, and the comparison of the two assessment methods showed that the species sensitivity distribution assessment better reflected the accumulation and feeding behavior of organisms to pollutants compared to the pollution load index.

PKM2 allosteric converter: A self-assembly peptide for suppressing renal cell carcinoma and sensitizing chemotherapy.

Stronger intrinsic Warburg effect and resistance to chemotherapy are the responses to high mortality of renal cell carcinoma (RCC). Pyruvate kinase M2 (PKM2) plays an important role in this process. Promoting PKM2 conversion from dimer to tetramer is a critical strategy to inhibit Warburg effect and reverse chemotherapy resistance. Herein, a PKM2 allosteric converter (PAC) is constructed based on the "in vivo self-assembly" strategy, which is able to continuously stimulate PKM2 tetramerization. The PAC contains three motifs, a serine site that is protected by enzyme cleavable ß-N-acetylglucosamine, a self-assembly peptide and a AIE motif. Once PAC nanoparticles reach tumor site via the EPR effect, the protective and hydrophilic ß-N-acetylglucosamine will be removed by over-expressed O-GlcNAcase (OGA), causing self-assembled peptides to transform into nanofibers with large serine (PKM2 tetramer activator) exposure and long-term retention, which promotes PKM2 tetramerization continuously. Our results show that PAC-induced PKM2 tetramerization inhibits aberrant metabolism mediated by Warburg effect in cytoplasm. In this way, tumor proliferation and metastasis behavior could be effectively inhibited. Meanwhile, PAC induced PKM2 tetramerization impedes the nuclear translocation of PKM2 dimer, which restores the sensitivity of cancer cells to first-line anticancer drugs. Collectively, the innovative PAC effectively promotes PKM2 conversion from dimer to tetramer, and it might provide a novel approach for suppressing RCC and enhancing chemotherapy sensitivity.

[Formation process of nitrogenous disinfection byproduct trichloronitromethane in drinking water and its influencing factors].

A novel method is described in this paper, which uses methyl tertiary butyl ether (MTBE) as extractant and 1,2-dibromopropane as internal standard for the determination of nitrogenous disinfection byproduct trichloronitromethane (TCNM) by gas chromatography mass spectrometry (GC-MS). The formation process of TCNM and its influencing factors were evaluated with methylamine as the precursor during chlorination. The results indicated that the TCNM amount produced under alkaline condition was higher than those produced under the neutral and acidic conditions, and the TCNM amount increased with the increase of pH value. It was found that the TCNM amount increased with the increase of chlorine addition when the chlorine dosage was in the range of 2-8 mmol x L(-1). However, the TCNM amount was reduced when the chlorine dosage was enhanced from 8 mmol x L(-1) to 12 mmol x L(-1), under which conditions the concentration of free chlorine was higher and methylamine was turned into nitriles and aldehydes through other reactions. It was also found that the TCNM amount increased with the increase of methylamine addition when the methylamine dosage was in the range of 0.5-4 mmol x L(-1). Temperature was another important factor that affected the TCNM formation from methylamine especially in the range of 10-30 degrees C and the higher the temperature, the more the TCNM amount produced. The formation process of TCNM from methylamine by chlorination was in accordance with the mechanism of an electrophilic reaction, in which HClO and ClO(-) could be used as the electrophilic reagents to attack methylamine and then to form TCNM.