Effect of the topology on the antibacterial activity of cationic polythioether synthesized by all-click chemistry

Cationic compounds often serve as antibacterial materials for a wide range of applications. However, the relationship of topology−antibacterial activity has been rarely revealed. Herein, three cationic polythioethers (CPTEs) with hyperbranched topologies are well designed and facilely synthesized via an all-click chemistry strategy (including thiol-ene and epoxy-amine additions). These as-prepared CPTEs were found to exhibited outstanding antibacterial activity against Escherichia coli and Staphylococcus aureus with minimum inhibitory concentrations against E. coli of 7.3, 14.6, and 14.6 μg ml⁻¹, and against S. aureus of 14.6, 29.2, and 29.2 μg ml⁻¹, respectively. The antibacterial activity is coincident with their degree of branching (DB, their DB values of 0.81, 0.48, and 0.27), which is mainly attributed to the inherent three-dimensional structure. The present strategy reveals the relationship of polymer topology and antibacterial activity, providing a novel possibility for designing and/or synthesis of high-efficiency antibacterial agents.     

离子液体功能高分子

离子液体功能高分子(ILFPs)是含离子液体结构的有机高分子,主要由不饱和单体聚合得到.此类高分子结合了离子液体所具有的独特性质,成为目前研究的热点.本文总结了近几年国内外有关ILFPs的最新研究成果,将现有的几十种ILFPs按与高分子链直接相连的离子的种类归为聚阳离子型、聚阴离子型和内盐型3类,介绍了各类ILFPs的合成方法及影响Tg大小的各种结构因素.此外,本文重点对ILFPs在聚合物电解质、表面活性剂、催化剂、生物酶载体及气体吸附剂等方面的应用进行了综述.最后提出了ILFPs的研究中尚待解决的诸如品种不多、结构表征不详等问题及今后可能的发展方向.     

Stereocontrol during photo-initiated controlled/living radical polymerization of acrylamide in the presence of Lewis acids

Poly(acrylamide) (PAM) with controlled molecular weight and tacticity was prepared by UV-irradiation-initiated controlled/living radical polymerization in the presence of dibenzyl trithiocarbonate (DBTTC) and Y(OTf)₃. The rapid and facile photo-initiated controlled/living polymerization at ambient temperature led to controlled molecular weight and narrow polydispersity (M_w/M_n = 1.12-1.24) of PAM. The coordination of Y(OTf)₃ with the last two amide groups in the growing chain radical effectively enhanced isotacticity of PAM. The isotactic sequence of dyads (m), triads (mm) and pentads (mmmm) in PAM were 70.32%, 50.95%, and 29.97%, respectively, which were determined by the resonance of methine (CH) groups in PAM under ¹³C NMR experiment. Factors affecting stereocontrol during the polymerization were studied, including the type of Lewis acids, concentration of Y(OTf)₃, and monomer conversion. It is intriguing that the meso tacticity increased gradually with chain propagation and quite higher isotacticity (m = 93.01%, mm = 86.57%) was obtained in the later polymerization stage (conversion 65-85%).     

The Asymptotic Expansion of Solutions for the Navier-Stokes Equations with Large Parameters

In this paper, we decomposite the coefficient matrix of the Navier-Stokes equations with large parameter in λ power. By factor analysis and energy estimation, the long time existence and asymptotic expansion of the solution tor the system are obtained. Key words Navier-Stokes equations; expansion; approximation.     

丰满坝溢流面裂缝问题研究

本文对丰满大坝溢流面新浇混凝土裂缝进行了表面调查、无损性态检测;采用有限元法模拟浇筑过程的应力分布。在现场调查、检测和理论研究相结合的基础上,对裂缝成因进行了较全面的分析,这将对寻求裂缝补强方法和东北寒冷地区大坝补强加固可行方案的提出具有参考价值。     

微波辐射下水相中3,5-双亚苄基哌啶-4-酮衍生物的合成

利用微波辐射, 以碳酸钾为催化剂, 快速于水相中合成了一系列3,5-双亚苄基哌啶-4-酮衍生物, 所合成化合物的结构经红外光谱、核磁共振光谱和高分辨率质谱予以确证.     

微波辐射下吡啶[2,3-d]嘧啶衍生物的高效合成

本文以等摩尔的芳醛,巴比妥酸（或1,3-二甲基巴比妥酸）,5-氨基-2-甲基苯[d]噻唑为原料,以醋酸和乙二醇为溶剂,微波辐射下多组分一锅法合成了一系列新的吡啶[2,3-d]嘧啶衍生物。这种方法具有产率高,操作简便,反应时间短等优点。     

Electrodeposition of CuInSe2 films by an alternating double-potentiostatic method using nearly neutral electrolytes

One step electrodeposition with an alternating double-potentiostatic(DPSED) program was used to prepare CuInSe₂ thin films in nearly neutral aqueous electrolytes with sodium citrate complex. Linear sweep voltammetry(LSV) was measured to probe voltammetric properties of electrolytes with respect to Cu, In and Se individual precursor and their mixed solutions. Compositional and structural characteristics of the as-deposited and annealed films at 400 °C in Ar atmosphere for 0.5 h were analyzed by XRD and XPS. The results showed that reduction of Cu²⁺ to Cu⁺ at one potential point of ?800 mV and subsequently formation of CuIn alloy as well as metal In and amorphous Se at the other potential point of ?1400 mV were responsible for synthesis of CISe chalcopyrite. Composition self-regulation made DPSED films have three elements co-deposition and more uniform element distribution, which promoted chalcopyrite CISe formation.     

Fabrication and characterization of nanocapsules containing <Emphasis Type="Italic">n</Emphasis>-dodecanol by miniemulsion polymerization using interfacial redox initiation

Phase change material nanocapsules with n-dodecanol as the core and styrene-butyl acrylate copolymer as the shell were prepared by miniemulsion polymerization using interfacial redox initiation. The morphology, particle size, polydispersity index, thermal properties, and structure of the nanocapsules were characterized by TEM, laser particle diameter analyzer, DSC, TGA, and FT-IR. When the monomers/n-dodecanol mass ratio of 1:1 was used, the phase change enthalpy and encapsulation efficiency of the nanocapsules reached to 109.2 J/g and 98.4%, respectively. The thermal decomposition temperature of the nanocapsules was about 195 °C. Spherical nanocapsules with a mean diameter of 100 nm and a phase change temperature of 18.4 °C were obtained, which have good energy storage potential.     

Preparation and evaluation of a mixed-bed immunoaffinity column for selective purification of sixteen sulfonamides in pork muscle

This paper describes the preparation of a novel mixed-bed immunoaffinity chromatography (IAC) column by coupling four monoclonal antibodies against different sulfonamides (SAs) to Sepharose 4B. The IAC column can be used to simultaneously extract and purify 16 SAs in pork muscle. The dynamic column capacities for all SAs in mixed standard solution were between 312 and 479 ng/mL gel. After simple extraction and IAC cleanup, the sample solution can be directly injected for liquid chromatography-ultraviolet analysis. The recoveries of SAs from spiked samples at levels of 25, 50 and 100 μg/kg ranged from 83.3 to 103.1% with variation coefficient less than 8.6%. The comparison of IAC with liquid-liquid extraction and solid phase extraction indicated that IAC has better purification effect and needs less organic solution than conventional methods, thus it would be an ideal method for selective purification of SAs in pork muscle.