Gene Cloning,Expression, and Characterization of an Exo-inulinase from Paenibacillus polymyxa ZJ-9

An inulinase-producing strain, Paenibacillus polymyxa ZJ-9, was isolated from natural sources to produce R,R-2,3-butanediol via one-step fermentation of raw inulin extracted from Jerusalem artichoke tubers. The inulinase gene from P. polymyxa ZJ-9 was cloned and overexpressed in Escherichia coli BL21 (DE3), and the purified recombinant inulinase was estimated to be approximately 56 kDa by both sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE) and gel filtration chromatography. This result suggests that the active form of the inulinase is probably a monomer. Terminal hydrolysis fructose units from the inulin indicate that enzymes are exo-inulinase. The purified recombinant enzyme showed maximum activity at 25 °C and pH 6.0, which indicate its extreme suitability for industrial applications. Zn²⁺, Fe²⁺, and Mg²⁺ stimulated the activity of the purified enzyme, whereas Co²⁺, Cu²⁺, and Ni²⁺ inhibited enzyme activity. The K _m and V _max values for inulin hydrolysis were 1.72 mM and 21.69 μmol min^?1 mg^?1 protein, respectively. The same parameters toward sucrose were 41.09 mM and 78.7 μmol min^?1 mg^?1 protein, respectively. Considering its substrate specificity and other enzymatic characteristics, we believe that this inulinase gene from P. polymyxa ZJ-9 could be transformed into other special bacterial strains to allow inulin conversion to other biochemicals and bioenergy through one-step fermentation.     

Single-Molecule Magnetism in Dy2 Cluster Based on a Schiff Base Ligand

Two dinuclear Ln^III-based clusters, namely [Dy₂L₂(NO₃)₂(DME)₄] ( 1 ) and [Gd₂L₂(NO₃)₂(DME)₄] ( 2 ) [H₂L = (E)-2-((2-hydroxybenzylidene)amino)phenol] were obtained under hydrothermal condition. Two Ln^III ions are bridged by two phenolic hydroxyl oxygen atoms, and the distances of them are 3.829 Å (Dy1–Dy1A) and 3.860 Å (Gd1–Gd1A). Two Dy1–O–Dy1A and Gd1–O–Gd1A angles are 109.4° and 109.8°, respectively. Magnetic studies reveal a weak antiferromagnetic interaction between Gd ions in complex 2 , and single-molecule magnet behavior for 1 with U_eff = 49.9 K and τ₀ = 1.54 × 10^–6 s.     

N-Confused Phlorin-Prodigiosin Chimera: meso-Aryl Oxidation and π-Extension Triggered by Peripheral Coordination

An N-confused phlorin isomer bearing a dipyrrin moiety at the α-position of the confused pyrrole ring ( 1 ) was synthesized. Pd^II and B^III coordination at the peripheral prodigiosin-like moiety of 1 afforded the corresponding complexes 2 and 3 . Reflux of 2 in triethylamine (TEA) converted the meso-phenyl into the Pd^II-coordinating phenoxy group to afford 4 . Under the same reaction conditions, TEA was linked to the α-position of the dipyrrin unit in 3 as an N,N-diethylaminovinyl group to afford 5 . Furthermore, peripheral coordination of B^III in 3 and 5 improved the planarity of the phlorin macrocycle and thus facilitated the coordination of Ag^III at the inner cavity to afford 3-Ag and 5-Ag , respectively. These results provide an effective approach for developing unique porphyrinoids through peripheral coordination.     

单层类水滑石纳米片的可控合成及规模生产展望

水滑石(LDHs)是一种阴离子黏土材料,由于其主体层板厚度的可调性,使其在光/电催化、电池、超级电容器、传感器以及生物医药等领域都具有广泛应用。降低层厚至单层可使材料的物理化学性质发生根本改变,从而优化催化性能。近期研究表明,利用自上而下,自下而上的方法,可以实现单层LDHs类材料的合成,但是受限于产量(g级)以及成本设备等问题,目前规模化制备高质量单层LDHs类材料还没有工业案例。成核晶化隔离法是目前唯一规模化合成纳米LDHs的工业化方法,具有成本低,产量可吨级放大等优点。本综述从合成方法、表征手段、应用三个角度讨论了单层及超薄LDHs的精准调控,详细论述了近期关于单层及超薄LDHs合成突破以及LDHs的规模化生产进展,并对其性能进行了总结,为后续设计高性能单层LDHs提供思路。     

磺酰脲类化合物在水稻田中的除草性能

水稻是我国重要的粮食作物,但杂草对水稻的产量和品质产生了严重影响。 化学防除是治理水稻田杂草最有效的途径。 文中设计合成了苯环2,6-取代和2,5-取代两个系列磺酰脲类化合物,并通过核磁共振波谱仪(NMR)和高分辨质谱仪(HRMS)等对其进行了结构表征。 通过水稻田除草活性和安全性测试发现化合物在水稻田中具有较好的除草活性,尤其是化合物10a对水稻田中的主要杂草稗草和醴肠除草活性(目测初筛防效大于90%)优于对照药醚苯磺隆和氯磺隆,安全性与之相当。     

The Redox Coupling Effect in a Photocatalytic RuII‐PdII Cage with TTF Guest as Electron Relay Mediator for Visible‐Light Hydrogen‐Evolving Promotion

A nanocage coupling effect from a redox Ru^II‐Pd^II metal–organic cage (MOC‐16) is demonstrated for efficient photochemical H₂ production by virtue of redox–guest modulation of the photo‐induced electron transfer (PET) process. Through coupling with photoredox cycle of MOC‐16, tetrathiafulvalene (TTF) guests act as electron relay mediator to improve the overall electron transfer efficiency in the host–guest system in a long‐time scale, leading to significant promotion of visible‐light driven H₂ evolution. By contrast, the presence of larger TTF‐derivatives in bulk solution without host–guest interactions results in interference with PET process of MOC‐16, leading to inefficient H₂ evolution. Such interaction provides an example to understand the interplay between the redox‐active nanocage and guest for optimization of redox events and photocatalytic activities in a confined chemical nanoenvironment.     

Three‐Dimensional Cuprous Lead Bromide Framework with Highly Efficient and Stable Blue Photoluminescence Emission

Considering the instability and low photoluminescence quantum yield (PLQY) of blue‐emitting perovskites, it is still challenging and attractive to construct single crystalline hybrid lead halides with highly stable and efficient blue light emission. Herein, by rationally introducing d¹⁰ transition metal into single lead halide as new structural building unit and optical emitting center, we prepared a bimetallic halide of [(NH₄)₂]CuPbBr₅ with new type of three‐dimensional (3D) anionic framework. [(NH₄)₂]CuPbBr₅ exhibits strong band‐edge blue emission (441 nm) with a high PLQY of 32 % upon excitation with UV light. Detailed photophysical studies indicate [(NH₄)₂]CuPbBr₅ also displays broadband red light emissions derived from self‐trapped states. Furthermore, the 3D framework features high structural and optical stabilities at extreme environments during at least three years. To our best knowledge, this work represents the first 3D non‐perovskite bimetallic halide with highly efficient and stable blue light emission.     

最小二乘法在液体粘滞系数实验中的应用

本文用多管落球法测得原始实验数据,运用最小二乘法进行处理,求得无限广延液体粘滞系数,并与直接作图法进行比较。     

同位素稀释结合固相萃取快速测定动物组织中β2-兴奋剂

本文采用同位素稀释结合固相萃取技术,测定动物组织中特布他林、克伦特罗、沙丁胺醇、莱克多巴胺4种β2-兴奋剂。动物组织加同位素内标D3-沙丁胺醇和D9-克伦特罗,经甲醇提取后,正己烷脱脂,过SLS离子交换固相萃取柱净化,用BSTFA 1%(φ)TMCS衍生,采用GC/MS进行测定,内标法定量。实验表明,动物组织中添加2.0~10.0μg/kg浓度水平的β2-兴奋剂,方法回收率在72.5%~97.9%,相对标准偏差1.0%~11.4%,线性范围为12.5~500μg/L,样品中特布他林、克伦特罗、沙丁胺醇、莱克多巴胺最低检出限分别为0.5μg/kg、1.0μg/kg、0.5μg/kg和1.0μg/kg。     

作为细胞微载体的明胶基缓释微球的制备

用改良的乳化冷凝法制备载牛血清蛋白(BSA)的大粒径明胶微球. 结果表明, 明胶水溶液的质量分数为25%、水相与油相体积比3∶20、搅拌速度300 r/min、交联剂用0.1 mL质量分数为25%的戊二醛、 表面活性剂用0.1 g span-80为制备平均直径约250 μm明胶微球的理想条件. 所制备微球的后处理方法不同, 则明胶微球的表面形貌也不同, 细胞粘附率不同. 空白明胶微球在体外可以完全降解, 载BSA的明胶微球对BSA具有良好的缓释性, 释放时间可长达30 d. 显微镜观察成纤维细胞在明胶微载体上生长良好.