Two compounds of [dmenH(2)(2+)][M(2)(HCOO)(6)(2-)] (M = Mn(II) and Co(II)), synthesized using N,N'-dimethylethylenediammonium (dmenH(2)(2+)) as the template, possess anionic metal formate frameworks of a novel binodal 6-connected (4(12).6(3))(4(9).6(6)) topology. They are the first coordination examples of this unique network closely related to niccolite and colquiriite and exhibit 3D long-range antiferromagnetic ordering with small spin canting.

Commonly used energy storage devices include stacked layers of active materials on two-dimensional sheets, and the limited specific surface area restricts the further development of energy storage. Three-dimensional (3D) structures with high specific surface areas would improve device performance. Herein, we present a novel procedure to fabricate macroscopic, high-quality, nitrogen-doped, 3D graphene/nanoparticle aerogels. The procedure includes vacuum filtration, freeze-drying, and plasma treatment, which can be further expanded for large-scale production of nitrogen-doped, graphene-based aerogels. The behavior of the supercapacitor is investigated using a typical nitrogen-doped graphene/Fe3O4 nanoparticle 3D structure (NG/Fe3O4). Compared with 3D graphene/Fe3O4 structures prepared by the traditional hydrothermal method, the NG/Fe3O4 supercapacitor prepared by the present method has a 153% improvement in specific capacitance, and there is no obvious decrease in specific capacitance after 1000 cycles. The present work provides a new and facile method to produce large-scale, 3D, graphene-based materials with high specific capacitance for energy storage.

Lithium ion batteries (LIBs) are widely used storage devices, which have a wide range of applications in electrical devices, hybrid electric vehicles, and for harvesting of renewable energy. [1] However, increasing demands for high-performance energy storage are unlikely to be satisfied by the theoretical capacities of the LIBs. [2] In particular, alternative cathode materials are required. [3] Recently, lithium-sulfur (Li-S) batteries have received attention owing to their high theoretical specificCarbon materials have received considerable attention as host cathode materials for sulfur in lithium-sulfur batteries; N-doped carbon materials show particularly high electrocatalytic activity. Efforts are made to synthesize N-doped carbon materials by introducing nitrogen-rich sources followed by sintering or hydrothermal processes. In the present work, an in situ hollow cathode discharge plasma treatment method is used to prepare 3D porous frameworks based on N-doped graphene as a potential conductive matrix material. The resulting N-doped graphene is used to prepare a 3D porous framework with a S content of 90 wt% as a cathode in lithium-sulfur cells, which delivers a specific discharge capacity of 1186 mAh g −1 at 0.1 C, a coulombic efficiency of 96% after 200 cycles, and a capacity retention of 578 mAh g −1 at 1.0 C after 1000 cycles. The performance is attributed to the flexible 3D structure and clustering of pyridinic N-dopants in graphene. The N-doped graphene shows high electrochemical performance and the flexible 3D porous stable structure accommodates the considerable volume change of the active material during lithium insertion and extraction processes, improving the long-term electrochemical performance.

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BackgroundGenome streamlining has emerged as an effective strategy to boost the production efficiency of bio-based products. Many efforts have been made to construct desirable chassis cells by reducing the genome size of microbes. It has been reported that the genome-reduced Bacillus subtilis strain MBG874 showed clear advantages for the production of several heterologous enzymes including alkaline cellulase and protease. In addition to enzymes, B. subtilis is also used for the production of chemicals. To our best knowledge, it is still unknown whether genome reduction could be used to optimize the production of chemicals such as nucleoside products.ResultsIn this study, we constructed a series of genome-reduced strains by deleting non-essential regions in the chromosome of B. subtilis 168. These strains with genome reductions ranging in size from 581.9 to 814.4 kb displayed markedly decreased growth rates, sporulation ratios, transformation efficiencies and maintenance coefficients, as well as increased cell yields. We re-engineered the genome-reduced strains to produce guanosine and thymidine, respectively. The strain BSK814G2, in which purA was knocked out, and prs, purF and guaB were co-overexpressed, produced 115.2 mg/L of guanosine, which was 4.4-fold higher compared to the control strain constructed by introducing the same gene modifications into the parental strain. We also constructed a thymidine producer by deleting the tdk gene and overexpressing the prs, ushA, thyA, dut, and ndk genes from Escherichia coli in strain BSK756, and the resulting strain BSK756T3 accumulated 151.2 mg/L thymidine, showing a 5.2-fold increase compared to the corresponding control strain.ConclusionsGenome-scale genetic manipulation has a variety of effects on the physiological characteristics and cell metabolism of B. subtilis. By introducing specific gene modifications related to guanosine and thymidine accumulation, respectively, we demonstrated that genome-reduced strains had greatly improved properties compared to the wild-type strain as chassis cells for the production of these two products. These strains also have great potential for the production of other nucleosides and similar derived chemicals.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-016-0494-7) contains supplementary material, which is available to authorized users.

Black phosphorus nanoparticles (BP NPs) possess great advantages in photocatalysis owing to the rich surface active sites, extremely high carrier mobility, and strong visible–near-infrared light response. However, the complex preparation process, poor stability, and rapid carrier recombination restrict their successful application in photocatalysis. Herein, the above problems are resolved by preparing BP NPs through a facile sonication-assisted hydrothermal method. To further improve the stability and photocatalytic activity, BP NPs are tightly anchored onto ZnS to prepare ZnS–BP porous nanosheets. With the Zn–P coordination bond built between them, higher stability, enhanced carrier transport ability, and excellent hydrogen adsorption and desorption equilibrium of photocatalysts are achieved. An efficient and recyclable photocatalytic hydrogen evolution rate of 1561 μmol h–1 g–1 is obtained under visible-light irradiation, which is superior to that of previously reported BP-based photocatalysts. Besides, the photocatalytic mechanism is investigated based on the theoretical calculations and experimental characterizations. The charge transfer dynamics are studied by surface photovoltage (SPV), ultrafast transient absorption (TA), X-ray absorption spectra (XAS), electrochemical impedance spectroscopy (EIS), and steady-state photoluminescence (PL) spectra. This work set a reference for the design of high-performance BP-related nanomaterials in solar energy storage and conversion.

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