Structure determination of selaginellins G and H from Selaginella pulvinata by NMR spectroscopy

Selaginellins G ( 1 ) and H ( 2 ), two new selaginellin derivatives, were isolated from the whole plant of Selaginella pulvinata. Their structures were elucidated, and complete assignments of the ¹H and ¹³C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, COSY and ROESY). Compound 1 displayed good antifungal activity against Candida albicans with an IC₅₀ value of 5.3 µg/ml. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and structure of a bowl-like molecule by threefold metathesis reactions

A bowl-like molecule was designed and efficiently synthesized by threefold metathesis reactions, and its structure was determined by NMR, MALDI-TOF MS spectrum, and X-ray crystallographic analysis.     

A Blue Light-inducible Phosphodiesterase Activity in the Cyanobacterium Synechococcus elongatus

A blue light-inducible phosphodiesterase (PDE) activity, specific for the hydrolysis of cyclic di-GMP (c-di-GMP), has been identified in a recombinant protein from Synechococcus elongatus. Blue light (BL) activation is accomplished by a light, oxygen, voltage (LOV) domain, found in plant phototropins and bacterial BL photoreceptors. The genome of S. elongatus contains two genes coding for proteins with LOV domains fused to EAL domains (SL1 and SL2). In both cases, a GGDEF motif is placed in between the LOV and the EAL motifs. Such arrangement is frequently found with diguanylate-cyclase (DGC) functions that form c-di-GMP. Cyclic di-GMP acts as a second messenger molecule regulating biofilm formation in many microbial species. Both enzyme activities modulate the intracellular level of this second messenger, although in most proteins only one of the two enzyme functions is active. Both S. elongatus LOV-GGDEF-EAL proteins were expressed in full length or as truncated proteins. Only the SL2 protein, expressed as a LOV-GGDEF-EAL construct, showed an increase of PDE activity upon BL irradiation, demonstrating this activity for the first time in a LOV-domain protein. Addition of GTP or c-di-GMP did not affect the observed enzymatic activity. In none of the full-length or truncated proteins was a DGC activity detected.     

Solitary wave solutions and kink wave solutions for a generalized KDV-mKDV equation

Bifurcation method of dynamical systems is employed to investigate solitary wave solutions and kink wave solutions of the generalized KDV-mKDV equation. Under some parameter conditions, their explicit expressions are obtained.     

Synthesis of propylene carbonate from carbon dioxide using trans‐dichlorotetrapyridineru‐ thenium(II) as catalyst

trans‐Dichlorotetrapyridineruthenium(II) [trans‐RuCl₂(py)₄] was synthesized and the structure was determined by single crystal X‐ray crystallography. Highly efficient formation of propylene carbonate (PC) from carbon dioxide and propylene oxide was achieved by using a catalyst system composed of trans‐RuCl₂(py)₄ and hexadecyl trimethyl ammonium bromide under mild conditions (4h, 80 °C, 3.0 MPa). PC was obtained in nearly 100% selectivity without the formation of a polymer. The catalyst could be recycled constantly many times without any significant loss of its catalytic activity. On the basis of the results, a mechanism for the reaction was proposed. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

A facile method for the preparation of monodisperse hollow silica spheres with controlled shell thickness

This article presents a facile, effective, mild synthesis process for well‐defined hollow spheres by using cationic polystyrene (PS) submicro‐particles as templates. In this approach, the cationic PS templates can be first prepared via emulsifier‐free polymerization by using the cationic monomer 2‐(methacryloyloxy) ethyltrimethylammonium chloride as comonomer, then, the silica shells from the sol‐gel process of tetraethoxysilane were coated on the surfaces of template particles via electrostatic interaction, finally the PS was dissolved in situ by modification of the reaction conditions in the same medium to form monodisperse hollow silica spheres with controlled shell thickness. Fourier transform‐infrared spectroscopy, thermogravimetric analysis, Brunauer‐Emmett‐Teller, transmission electron microscopy, and scanning electron microscope measurements were used to characterize these hollow silica spheres. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1332–1338, 2010     

Novel Method for Preparing NH4NiPO4·6H2O: Hydrogen Bonding Coacervate Selective Self-assembly

The single phase NH₄NiPO₄·6H₂O was synthesized by solid‐state reaction at room temperature using NiSO₄·6H₂O and (NH₄)₃PO₄·3H₂O as raw materials. The NH₄NiPO₄·6H₂O and its calcined products were characterized using X‐ray powder diffraction (XRD), thermogravimetry and differential thermal analyses (TG/DTA), Fourier transform IR (FT‐IR), ultraviolet‐visible (UV‐vis) absorption spectroscopy, and scanning electron microscopy (SEM). The results showed that the product dried at 80°C for 3 h was orthorhombic NH₄NiPO₄·6H₂O [space group Pmm2(25)], and surfactant polyethylene glycol (PEG)‐400 can direct growth of crystal NH₄NiPO₄·6H₂O. The thermal process of NH₄NiPO₄·6H₂O experienced three steps, which involve the dehydration of the five crystal water molecules at first, and then deamination, dehydration of the one crystal water, intramolecular dehydration of the protonated phosphate groups together, at last crystallization of Ni₂P₂O₇. The product of thermal decomposition at 150°C for 2 h, orthorhombic NH₄NiPO₄·H₂O, is layered compound with an interlayer distance of 0.8370 nm.     

中等组分网状结构局部微变对功能梯度板三维动力特性的影响

利用细观元方法根据材料实际金相图片信息进行材料参数输入,对发生局部网格变化的功能梯度板件进行三维动力特性分析,完成了材料细观结构与构件宏观响应间的跨尺度分析.细观元法在结构的常规有限元内部设置密集的细观单元来反映材料细观构造,此方法可实现材料细观结构到构件宏观响应的直接过渡分析,为具有细观结构微观变化的功能梯度板件的分析提供一种新的工具.利用细观元法对具有中等组分网状结构发生局部微变的功能梯度板进行三维动力特性分析,给出其固有频率及振型的三维分布,特别是功能梯度板应力振型的平面等值线图差异,得到较好的结果.     

Erratum to "Aerosol pollution in China: Present and future impact on environment"

PARTICUOLOGY regrets that the above paper was mistakenly classified as a ‘Review’ rather than an ‘Invited paper’ when originally published in volume 7, issue 6, 426–431.