Trace water in a BF3·OEt2 system: a facile access to sulfinyl alkenylsulfones from alkynes and sodium sulfinates.

A highly efficient and operationally simple method for the synthesis of ß-sulfinyl alkenylsulfones through a BF3·OEt2-promoted reaction of alkynes and sodium sulfinates is developed, successfully avoiding the complicated anhydrous treatment before the reaction and greatly simplifying the reaction conditions. As a facile and selective route to the targets, it features good functional group compatibility, mild conditions, easily available starting materials, and excellent yields. Notably, the trace water in solvent plays a key role in promoting the reaction, which provides a more practical pathway for the utilization of the BF3·OEt2 catalytic system.

Fine-tuning benzazole-based probe for the ultrasensitive detection of Hg2+ in water samples and seaweed samples.

Developing potentially toxic metal ion probes is significant for environment and food safety. Although Hg2+ probes have been extensively studied, small molecule fluorophores that can integrate two applications of visual detection and separation into one unit remain challenging to access. Herein, by incorporating triphenylamine (TPA) into tridentate skeleton with an acetylene bridge, 2,6-bisbenzimidazolpyridine-TPA (4a), 2,6-bisbenzothiazolylpyridine-TPA (4b) and 2,6-bisbenzothiazolylpyridine-TPA (4c) were first constructed, expectably showing distinct solvatochromism and dual-state emission properties. Since the diverse emission properties, the fluorescence detection of 4a-4b can be achieved with an ultrasensitive response (LOD = 10-11 M) and efficient removal of Hg2+. More interestingly, 4a-4b can not only be developed into paper/film sensing platform, but also reliably detect Hg2+ in real water and seaweed samples, with recoveries ranging from 97.3% to 107.8% and a relative standard deviation of less than 5%, indicating that they have excellent application potential in the field of environmental and food chemistry.

Regulating donor-acceptor system toward highly efficient dual-state emission for sensitive response of nitroaromatic explosives.

Dual-state emission luminogens (DSEgens) as fluorophores emit efficiently in solution and solid forms have gained increasing concern in the field of chemical sensing. Recent efforts by our group led to the identification of DSEgens as an easy-to-visualize nitroaromatic explosives (NAEs) detection platform. However, none of the previously studied NAEs probes show effective improvement in sensitivity. Here, we designed a series of benzoxazole-based DSEgens through multiple strategies driven by theoretical calculations, revealing their improved detecting performance on NAEs. Compounds 4a-4e exhibit thermal- and photo-stability, large Stokes shift as well as sensitivity solvatochromism (except for 4a and 4b). A subtle balance between rigid conjugation and distorted conformation endows these D-A type fluorophores 4a-4e with DSE properties. Furthermore, 4d and 4e show aggregation-induced emission phenomenon caused by distorted molecular conformation and restricted intramolecular rotation. Interestingly, DSEgen 4e displays anti-interference and sensitivity towards NAEs with a detection limit of 10-8 M. It can be applied for expedient and distinct visual identification of NAEs not only in solution but also on filter paper and film, supporting this new DSEgen as reliable NAEs chemoprobe.

An investigation on catalytic nitrite reduction reaction by bioinspired CuII complexes.

Catalytic nitrite reductions by CuII complexes containing anionic Me2Tp, neutral Me2Tpm, or neutral iPrTIC ligands in the presence of L-ascorbic acid, which served as an electron donor and proton source, were investigated. The results showed that auxiliary ligands are important for copper-mediated catalytic nitrite reduction. Furthermore, the electronic effects of the ligand govern the nitrite reduction efficiency, which should be considered at two control points: one is the susceptibility of the LCuI-nitrite species to protonation and the other is the susceptibility of LCuII to reduction giving LCuI. In addition, an external strong acid leads to the production of nitrous acid, which may suggest that the reactivity of nitrous acid toward the LCuI species is a third control point.

Rational Design and Facile Synthesis of Dual-State Emission Fluorophores: Expanding Functionality for the Sensitive Detection of Nitroaromatic Compounds.

Six novel benzimidazole-based D-π-A compounds 4 a-4 f were concisely synthesized by attaching different donor/acceptor units to the skeleton of 1,3-bis(1H-benzimidazol-2-yl)benzene on its 5-position through an ethynyl link. Due to the twisted conformation and effective conjugation structure, these dual-state emission (DSE) molecules show intense and multifarious photoluminescence, and their fluorescence quantum yields in solution and solid state can be up to 96.16 and 69.82 %, respectively. Especially, for excellent photostability, obvious solvatofluorochromic and extraordinary wide range of solvent compatibility, DSE molecule 4 a is a multifunctional fluorescent probe for the visual detection of nitroaromatic compounds (NACs) with the limit of detection as low as 10-7 M. The quenching mechanism has been proved as the results of photoinduced electron transfer and fluorescence resonance energy transfer processes. Importantly, probe 4 a can sensitively detect NACs not only in real water samples, but also on 4 a-coated strips and 4 a@PBAT thin films.

Simple inorganic base promoted C-N and C-C formation: synthesis of benzo[4,5]imidazo[1,2-a]pyridines as functional AIEgens used for detecting picric acid.

Metal-free catalyzed intermolecular tandem Michael addition/cyclization has been developed for the synthesis of benzo[4,5]imidazo[1,2-a]pyridines from α-bromocinnamaldehyde and 2-substituted benzimidazoles. The reaction promoted by a simple inorganic base displays moderate to good yields and good functional group tolerance. The optical properties of some typical products have been investigated. We found that, due to the presence of the benzene ring at the C1-position of benzo[4,5]imidazo[1,2-a]pyridines which restricts intramolecular motion, as a new type of aggregation-induced emission (AIE) luminogen (AIEgen), they show very good solid-state fluorescence with quantum yields up to 88.80%. Importantly, the AIE performance of compound 3b can be useful to detect the nitroaromatic explosive picric acid (PA) with a detection limit and quenching constant of 42.5 nM and 7.27 × 104 M-M, respectively.

High-Affinity Sulfate Transporter Sultr1;2 Is a Major Transporter for Cr(VI) Uptake in Plants.

Chromate (Cr[VI]) is a highly phytotoxic contaminant that is ubiquitous in soils. However, how Cr(VI) is taken up by plant roots remains largely unknown. Here, we show that the high-affinity sulfate transporter Sultr1;2 is responsible for Cr(VI) uptake by the roots of Arabidopsis thaliana. Sultr1;2 showed a much higher transport activity for Cr(VI) than Sultr1;1 when expressed in yeast cells. Knockdown of Sultr1;2 expression in Arabidopsis markedly reduced the Cr(VI) uptake rate, whereas knockout of Sultr1;1 had no or little effect. A double-knockout mutant (DKO) of the two genes lost the ability of Cr(VI) uptake almost completely. The Sultr1;2 knockdown mutant or DKO plants displayed higher resistance to Cr(VI) under normal sulfate conditions as a consequence of the lower tissue Cr accumulation. Overexpression of Sultr1;2 substantially increased Cr(VI) uptake with shoot Cr concentration being 1.6-2.0 times higher than that in the wild-type. These results indicate that Sultr1;2 is a major transporter responsible for Cr(VI) uptake in Arabidopsis, while Sultr1;1 plays a negligible role. Taken together, our study has identified a major transporter for Cr(VI) uptake in plants, providing potential strategies for engineering plants with low Cr accumulation and consequently enhanced Cr(VI) resistance and also plants with enhanced accumulation of Cr for the purpose of phytoremediation.

Microbial Processes Mediating the Evolution of Methylarsine Gases from Dimethylarsenate in Paddy Soils.

Arsenic (As) biovolatilization is an important component of the global As biogeochemical cycle. Soils can emit various methylarsine gases, but the underlying microbial processes remain unclear. Here, we show that the addition of molybdate (Mo), an inhibitor of sulfate-reducing bacteria, greatly enhanced dimethylarsine evolution from dimethylarsenate [DMAs(V)] added to two paddy soils. Molybdate addition significantly affected the microbial community structure. The aerobic enrichment cultures from both soils volatilized substantial amounts of dimethylarsine from DMAs(V) in the presence of Mo, whereas the anaerobic enrichment cultures did not. A Bacillus strain (CZ-2) capable of reducing DMAs(V) to dimethylarsine was isolated from the aerobic enrichment culture, and its volatilization ability was enhanced by Mo. RNA-seq analysis identified 10 reductase genes upregulated by Mo. Addition of the reducing agent NADH increased dimethylarsine volatilization by strain CZ-2, suggesting that DMAs(V) reductase is an NADH-dependent enzyme. The strain could not methylate arsenite or convert monomethylarsenate and DMAs(V) to trimethylarsine. Our results show that dimethylarsine evolution from DMAs(V) is independent of the As methylation pathway and that Mo enhances dimethylarsine evolution from paddy soils by shifting the microbial community structure and enhancing the reduction of DMAs(V) to dimethylarsine, possibly through upregulating the expression of DMAs(V) reductase gene(s).

A highly sensitive fluorescent chemosensor for selective detection of zinc (II) ion based on the oxadiazole derivative.

A novel fluorescent chemosensor based on the oxadiazole, 2-(2-hydroxyphenyl)-5-(4-methoxyphenyl)-1,3,4-oxadiazole, was designed and synthesized. The interaction of the oxadiazole with different metal ions had been investigated through UV-vis absorption and fluorescence spectra in 9:1 (v/v) ethanol-water (pH=7.0) solution. The oxadiazole showed a pronounced fluorescence enhancement at 430nm upon addition of Zn2+ in aqueous solution, whereas it had no apparent interference from other metal ions. The results indicated that the oxadiazole possessed high selectivity and sensitivity to Zn2+ ion. The stoichiometric ratio between the oxadiazole and Zn2+ ion was calculated to be 2:1 by Job plot experiment, meanwhile their binding modes was confirmed by 1H NMR and mass spectrometry. Their association constant was determined to be 1.95×105M-1 and the detection limit for Zn2+ ion was 6.14×10-7mol/L.

[Investigation of intestinal nematode infections in Hongze County, Jiangsu Province].

OBJECTIVE: To understand the situation of intestinal nematode infections and assess the preventive effects, so as to provide the evidence for formulating the further measures of prevention. METHODS: Five villages from 5 townships of different geographical locations were selected and 500 residents of each village were surveyed. The eggs of intestinal nematodes were detected by the Kato-Katz technique, and 50 students and 50 residents per village were investigated by questionnaires about health education. RESULTS: Among 3 011 people detected, 17 persons were infected with intestinal nematodes and the total infection rate was 0.56%. The rates of Ascaris lumbricoides, hookworm, Trichuris trichiura, Enterobius vermicularis, and Trichostrongylus were 0.10%, 0.33%, 0.03%, 0.03% and 0.07%, respectively. The awareness rate of health knowledge was 97.80% and the formation rate of health behavior was 97.00%. CONCLUSION: The infection rates of intestinal nematodes, the awareness rate of health knowledge and the formation rate of health behavior in the population of Hongze County have achieved the criteria of effective control of intestinal parasitic diseases.

Transcriptome analysis reveals unique C4-like photosynthesis and oil body formation in an arachidonic acid-rich microalga Myrmecia incisa Reisigl H4301.

BACKGROUND: Arachidonic acid (ArA) is important for human health because it is one of the major components of mammalian brain membrane phospholipids. The interest in ArA inspired the search for a new sustainable source, and the green microalga Myrmecia incisa Reisigl H4301 has been found a potential ArA-producer due to a high content of intracellular ArA. To gain more molecular information about metabolism pathways, including the biosynthesis of ArA in the non-model microalga, a transcriptomic analysis was performed. RESULTS: The 454 pyrosequencing generated 371,740 high-quality reads, which were assembled into 51,908 unique sequences consisting of 22,749 contigs and 29,159 singletons. A total of 11,873 unique sequences were annotated through BLAST analysis, and 3,733 were assigned to Gene Ontology (GO) categories. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis uncovered a C4-like photosynthesis pathway in M. incisa. The biosynthesis pathways of lipid particularly those of ArA and triacylglycerol (TAG) were analyzed in detail, and TAG was proposed to be accumulated in oil bodies in the cytosol with the help of caleosin or oil globule-associated proteins. In addition, the carotenoid biosynthesis pathways are discussed. CONCLUSION: This transcriptomic analysis of M. incisa enabled a global understanding of mechanisms involved in photosynthesis, de novo biosynthesis of ArA, metabolism of carotenoids, and accumulation of TAG in M. incisa. These findings provided a molecular basis for the research and possibly economic exploitation of this ArA-rich microalga.

[Study on potential risks of schistosomiasis transmission in Grand Canal West water diversion route of eastern route project of South-to-North Water Diversion Project].

OBJECTIVE: To understand the potential risks of Oncomelania hupensis diffusion and schistosomiasis transmission in the Grand Canal west water diversion route of the eastern route project of the South-to-North Water Diversion Project. METHODS: The engineering layout from Nanyun west floodgate to Hongze Lake, the aquaculture along Hongze Lake, and the data of hydrology and transferred water were investigated. The investigations on Oncomelania hupensis and schistosomiasis were carried out in the surveillance sites of Jinbao Channel and Hongze Lake. The possibilities of snail spreading and schistosomiasis transmission were researched. RESULTS: Oncomelania snails lacked their breeding environment and ecological condition in the Hongze Lake region. The engineering facilities of the Jinhu and Hongze pumping stations went against the snail spreading. The water levels at all steps decreased gradually from Hongze Lake to Jinbao Channel. Therefore, the pumping stations were necessary when the water transferred to Hongze Lake. The multi-year average diverted water volume reached 2.558 billion cubic meters a year in the Jinbao Channel. Of the total diverted water volume, there was 75% of the volume in drought years. The Oncomelania snails were not found in the surveillance sites of the Jinbao Channel and the Hongze Lake region from 2008 to 2011. A total of 3 088 residents were examined with the serology tests and the positive rate was 0.29% in 2008. Totally 4 758 overwater flow people were examined with the serology tests and the positive rate was 2.42% from 2008 to 2011. The serum positive rate was higher in the overwater flow people than that in the residents (chi2 = 0.083, P < 0.01). The stool examinations were all negative in the above mentioned serum positive people. CONCLUSIONS: The Hongze Lake area has still no Oncomelania snail breeding and schistosomiasis endemic so far. There are also no schistosomiasis re-prevalent signs in the Jinbao Channel area where schistosomiasis was once prevalent. The Oncomelania snail breeding and diffusion, and schistosomiasis endemic are unlikely to appear in the Grand Canal west water diversion route of the eastern route project of the South-to-North Water Diversion and Hongze Lake area.