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Due to the merits of low cost, safety, environmental friendliness, and abundant sodium reserves, non-aqueous and aqueous sodium-ion batteries are wonderful alternatives for large-scale energy storage.

Nanorod-like TiO 2 photocatalysts with controllable particle size for hydrogen production were synthesized based on H 2 Ti 3 O 7 precursors using hydrothermal and ion exchange methods. The characteristics of TiO 2 photocatalysts, such as morphology, specific areas and crystalline quality, can be adjusted by changing hydrothermal conditions, thus optimizing its photocatalytic activity for hydrogen evolution. The TiO 2 nanorod possesses the highest photocatalytic activity, even higher than P25, when the hydrothermal temperature is 140 o C, which should be ascribed to its large specific area and good crystalline quality. Non-noble metal Cu as a substitute of Pt was loaded on the surface of TiO 2 nanorod to promote the photocatalytic hydrogen production. It was confirmed that, during the photocatalytic reaction process, Cu 0 rather than CuOx acted as active sites to enhance the photocatalytic activity. The highest photocatalytic H 2 evolution rate of Cu/TiO 2 reaches 1023.8 μmol•h-1 when the amount of loading is 0.1 wt%, reaching the 20 times of that of bare TiO 2 (49.4 μmol•h-1) and approaching that of Pt/TiO 2 (1161.7 μmol•h-1). Non-noble metal Cu not only facilitated the separation of carriers, but reduced the overpotential of hydrogen evolution, thus promoting the photocatalytic activity for hydrogen production.

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BackgroundBacillus thuringiensis X022, a novel strain isolated from soil in China, produces diamond-shaped parasporal crystals. Specific mineral nutrients, such as Mg, Cu, and Mn, influence insecticidal crystal proteins (ICP) expression and the effects of these elements vary significantly. However, the molecular mechanisms of the effects caused by mineral elements have yet to be reported.ResultsThe ICP are mainly composed of Cry1Ca, Cry1Ac, and Cry1Da, which have molecular weights of about 130 kDa. ICP production was most efficient when Cu2+ was added at concentrations ranging from 10−6 to 10−4 mol/L at an initial pH of 8.0. Addition of Cu2+ also evidently increased the toxicity of fermentation broth to Spodoptera exigua and Helicoverpa armigera. After analyzing changes in proteome and fermentation parameters caused by Cu2+ addition, we propose that Cu2+ increases PhaR expression and consequently changes the carbon flow. More carbon sources was used to produce intracellular poly-β-hydroxybutyrate (PHB). Increases in PHB as a storage material bring about increases of ICP production.ConclusionsBacillus thuringiensis X022 mainly expresses Cry1Ca, Cry1Ac, and Cry1Da. Cu2+ increases the expression of Cry1Da, Cry1Ca, and also enhances the toxicity of fermentation broth to S. exigua and H. armigera.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-015-0339-9) contains supplementary material, which is available to authorized users.

The miniaturized optical emission spectrometry (OES) devices based on various microplasma excitation sources provide reliable tools for on-site analysis of heavy metal pollution, while the development of convenient and efficient sample introduction approaches is essential to improve their performances for field analysis. Herein, a small activated carbon electrode tip is employed as solid support to preconcentrate heavy metals in water and subsequently served as an inner electrode of the coaxial dielectric barrier discharge (DBD) to generate microplasma. In this case, heavy metal analytes in water are first adsorbed on the surface of the activated carbon electrode tip via a simple liquid–solid phase transformation during the sample loading process, and then, fast released to produce OES during the DBD microplasma excitation process. The corresponding OES signals are synchronously recorded by a charge-coupled device (CCD) spectrometer for quantitative analysis. This activated carbon electrode tip provides a new tool for sample introduction into the DBD microplasma and facilitates “insert-and-go” in subsequent DBD-OES analysis. With a multiplexed activated carbon electrode tip array, a batch of water samples (50 mL) can be loaded in parallel within 5 min. After drying the activated carbon electrode tips for 5 min, the DBD-OES analysis is maintained at a rate of 6 s per sample. Under the optimized conditions, the detection limits of 0.03 and 0.6 μg L–1 are obtained for Cd and Pb, respectively. The accuracy and practicability of the present DBD-OES system have been verified by measuring several certified reference materials and real water samples. This analytical strategy not only simplifies the sample pretreatment steps but also significantly improves the sensitivity of the DBD-OES system for heavy metal detection. By virtue of the advantages of high sensitivity, fast analysis speed, simple operation, low cost, and favorable portability, the upgraded DBD-OES system provides a more powerful tool for on-site analysis of heavy metal pollution.

An enantioselective direct Mannich reaction of different acetophenone derivatives with various substituted seven‐membered cyclic imines using (S)‐azetidine‐2‐carboxylic acid as an organocatalyst is described, which provides an efficient access to optically active 11‐substituted‐10,11‐dihydrodibenzo[b,f][1,4]oxazepine derivatives with 87–95 % ee. For α,β‐unsaturated ketone benzalacetone, the desired Mannich product was obtained with 72 % ee. A plausible transition state is established to explain the observed absolute stereochemistry of the Mannich products. The reaction can also be performed on a gram scale with no adverse effects on the yield and enantioselectivity. Furthermore, some simple transformations involving the Wittig olefination and the decarboxylative reduction of the Mannich products were performed.