An unprecedented 2D → 3D metal-organic polyrotaxane framework constructed from cadmium and a flexible star-like ligand

An unprecedented 2D → 3D metal-organic polyrotaxane framework, based on a new star-like tri(4-imidazolylphenyl)amine ligand, has been synthesized and characterized, which represents the first example of 2D → 3D polyrotaxane entangled in a parallel fashion.     

Effect of saponins on cell surface properties of Penicillium simplicissimum: performance on adsorption of cadmium(II)

Previous studies about the effect of biosurfactants on cell surface properties mainly focus on cell surface hydrophobicity. In the present study, the effects of plant-derived biosurfactants saponins on cell surface charge and the adsorption of cadmium(II) by Penicillium simplicissimum were studied. The pretreatment of saponins changed the optimal pH from 6 to 5 for Cd(II) adsorption. All the adsorption processes by the intact and saponins-pretreated biomasses followed the Langmuir isotherms better than the Freundlich isotherms. According to the Langmuir isotherms, the maximum adsorption of Cd(II) (qmax) was increased from 51.6 to 74.6 mg/l by the pretreatment of 0.025% saponins. The mechanisms were also analyzed by Fourier transform infrared spectrometer (FTIR), energy dispersive X-ray (EDAX), and scanning electron microscope (SEM) analysis. The results indicated that the pretreatment of saponins changed the cell surface charge of P. simplicissimum and therefore influenced the adsorption of cadmium(II).     

Redesign the α/β Fold to Enhance the Stability of Mannanase Man23 from <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

In this work, we engineered the α/β fold of mannanase Man23 based on its molecular structure analysis to obtain more stable variants. By introducing 31 single-site mutations in the α/β fold and shuffling them, the incorporation of four mutations (K178R, K207R, N340R, and S354R) displayed a good balance between high activity and stability at higher temperature and broader pH. This quartet variant was characterized by an almost threefold increased activity and a sevenfold increased stability compared to native mannanase Man23. Our results suggest that such work is safe to increase our target protein stability with no loss of activity.     

A Functional Electrocatalyst of Coordination Polymer Derived from Di-nuclear Nickel(II)-Glycine Cations and Wells–Dawson Polyoxoanions

Journal of Cluster Science - A new organic–inorganic hybrid, namely [Ni2(en)4(C2H3NO2)(H2O)][Ni(en)3][Ni(en)2][P2W18O62]·6H2O (1, en?=?1,2-ethylenediamine), was synthesized...     

有机试剂对锶火焰原子吸收光谱分析的增感机理

研究了火焰原子吸收光谱法中甲醇、甲醛、甲酸等6种有机试剂对元素Sr的增感行为,发现甲酸效果最佳。在选定的相对最佳条件下,增感效果高达70%。研究表明,甲酸所产生的增感效应主要在于其与Sr形成甲酸锶,改变了常规原子化机理,提高了火焰原子化效率。这一机理同样适用于甲酸存在下Ca、Ba等元素的火焰原子化。实验表明,甲酸对这两种碱土元素的增感效果分别达到54%和55%。甲酸对Sr的增感应用于高纯BaCO3中Sr含量测定,回收率达到100%～106%。     

阳离子选择性耗尽进样-胶束扫集法测定尿液中的麻黄碱和可待因

联用选择性耗尽进样和胶束扫集两种在线富集技术,建立了尿样中麻黄碱和可待因含量测定的灵敏方法,并通过日内、日间、柱间实验考察了方法的稳定性.胶束扫集电动色谱缓冲体系为80 mmol/L 十二烷基磺酸钠(SDS)-20 mmol/L NaH2PO4(pH 2.20)-18%乙腈(V/V),分离电压-20 kV,进样电压10 kV,进样时间150 s,测量波长200 nm.同时讨论了pH值、SDS浓度、选择性耗尽进样萃取液电导、进样电压、进样时间和进水长度等对分离效果的影响.结果显示,方法富集功能很强,对麻黄碱和可待因含的富集倍数分别达5800和2490以上.在优化条件下,方法线性关系良好(r=0.9999),麻黄碱和可待因的线性范围分别为0.500～16.0 μg/L和2.00～48.0 μg/L,检出限分别为0.10和0.80 μg/L.方法稳定性良好,日内、日间和柱间的RSD分别为2.6%,5.9%和6.6%.应用于实际尿样分析,回收率在96.8%～106%之间,RSD≤4.7%,结果比较满意.     

CO2-based Biodegradable Supramolecular Polymers with Well-tunable Adhesive Properties

Supramolecular adhesives that enable debonding on-demand are of significant research interest for the development of adaptive and smart materials,yet,biodegrable supramolecular adhesives have been rarely exploited.Herein,telechelic,three-armed and four-armed CO₂-based polyols with close molecular weights and various content(or carbonate unite content)have been synthesized via a zinc-cobalt double metal cyanide complex catalyzed ring-opening copolymerization of CO₂ and propylene oxide,and further exploited as sustainable and biodegradable building blocks for supramolecular polymers(SMPs)with 2-ureido-4[1H]-pyrimidinone(UPy)motifs.Notably,the orthogonal modulation of the CO₂ content and the topology of CO₂-based polyols provide a unique opportunity to fine-tune the surface energy as well as the cohesive strength of the resulting CO₂-based SMPs.Notably,a three-armed SMP with 44%CO₂(3UPy-CO₂-44%)can well balance the trade-off between surface energy and cohesive strength,therefore bestowing a high adhesive strength of 7.5 and 9.7 MPa towards stainless steel and wood substrates respectively by testing the corresponding single lap joints.Moreover,the light-responsive adhesion property of 3UPy-CO₂-44%has been demonstrated exemplarily by blending with a UV sensitizer.     

Magnetic graphene nanocomposite as an efficient catalyst for hydrogenation of nitroarenes

Graphene-Fe₃O₄ nanocomposite（G-Fe₃O₄） was synthesized by a chemical co-precipitation method which was used as an efficient catalyst for the reduction of nitroarenes with hydrazine hydrate.The method has been applied to a broad range of compounds with different properties and the yields were in the range of 75%-92%.The G-Fe₃O₄ catalyst can be readily recovered and reused 5 times without significant loss of the catalytic activity.     

Cu(OTf)2 catalyzed cross-coupling reaction of 1,3-dicarbonyl derivatives with 2-oxo-1-pyrrolidine compounds

An efficient method for the cross-coupling reactions of 1,3-dicarbonyl compounds with 2-oxo-1-pyrrolidine compounds 1 was developed. Cu(OTf)₂ catalyzed C–C bond forming reactions using substrates 1 with 1,3-dicarbonyl compounds in chloroform, providing the corresponding compounds of 2-oxo-1-pyrrolidine bearing 1,3-dicarbonyl moiety in moderate to good yields.