流动注射分光光度法测定微量硫氰酸根

基于３，５－Ｂｒ２－ＰＡＤＡＰ硫氰酸根分别与重铬酸根，铈（ＩＶ）在硫酸介质中反应成不稳定的蓝色产物，建立了两种测定微量硫氰酸根的流动注射分光光度新方法，在前一方法中，硫氰酸根含量在０．８０～７．２０ｍｇ／Ｌ范围内可定量测定，检出限为０．２７ｍｇ／Ｌ在后一方法中，硫氰酸根含量在０．８０～６．４０ｍｇ／Ｌ范围内呈线性，检出限为０．３０ｍｇ／Ｌ。当进样体积为１００μＬ时，进样频率为６０次／ｈ，所建立的两     

Comparison on effect of hydrophobicity on the antibacterial and antifungal activities of α-helical antimicrobial peptides

HPRP-A1, a 15-mer α-helical cationic peptide, was derived from N-terminus of ribosomal protein L1 (RpL1) of Helicobacter pylori. In this study, HPRP-A1 was used as a framework to obtain a series of peptide analogs with different hydrophobicity by single amino acid substitutions in the center of nonpolar face of the amphipathic helix in order to systematically study the effect of hydrophobicity on biological activities of -helical antimicrobial peptides. Hydrophobicity and net charge of peptides played key roles in the biological activities of these peptide analogs; HPRP-A1 and peptide analogs with relative higher hydrophobicity exerted broad spectrum antimicrobial activity against Gram-negative bacteria, Gram-positive bacteria and pathogenic fungi, but also showed stronger hemolytic activity; the change of hydrophobicity and net charge of peptides had similar effects with close trend and extent on antibacterial activities and antifungal activities. This indicated that there were certain correlations between the antibacterial mode of action and the antifungal mode of action of these peptides in this study. The peptides exhibited antimicrobial specificity for bacteria and fungi, which provided potentials to develop new antimicrobial drugs for clinical practices.     

电沉积表面修饰对染料敏化太阳电池微观性能影响机理研究

为了改善染料敏化太阳电池内电子的传输复合过程, 研究者尝试不同方法制备或改性TiO₂薄膜. 对TiO₂薄膜进行后处理, 在其表面引入一层小颗粒层, 是一种有效的方法并被广泛研究. 通过对TiO₂薄膜不同时间的电沉积表面修饰, 细致研究了表面修饰后染料敏化太阳电池微观性能的变化机制. 采用阳极氧化法在TiCl₃水溶液中对TiO₂薄膜进行电沉积后处理, 将溶液pH值调至2.2, 装置的反应速率由恒电位仪控制. 不同沉积时间电池带边移动以及电子传输复合的动力学过程, 借助强度调制光电流谱(IMPS)/强度调制光电压谱(IMVS)和电化学阻抗谱(EIS)等探测技术表征. 研究表明, 电沉积在TiO₂薄膜表面引入了大量浅能级陷阱态, 以致电势较高时电容随沉积时间延长增加明显. 不同时间的电沉积表面修饰在TiO₂薄膜表面形成了新的小颗粒层并改善了TiO₂颗粒间接触, 在改善电子注入及收集过程的同时, 也有效抑制了内部电子复合. IMPS/IMVS结果表明, 电沉积对动力学过程改善的效果受光强影响明显, 弱光下作用更为突出. 此外, 电池开路电压主要受带边移动及内部复合变化影响, 随沉积时间延长, 表面电荷的增多使TiO₂薄膜带边逐渐正移, 有效改善了光电流却限制了开路电压的提升. 在适合的电沉积时间下, 电沉积表面修饰可以同时改善光电流和光电压.     

Binary and ternary poly(lactic acid)/poly(ϵ-caprolactone) blends: The effects of oligo-ϵ-caprolactones upon mechanical properties

Oligo-ε-caprolactones(o-CL) have been utilized as principle secondary components within poly(lactic acid)[PLA]-based blends as well as additives within larger-sized PCL/PLA blends in an effort to fully complement the mechanical attributes of the respective polyesters. Dynamic mechanical thermal analysis(DMTA) shows that the presence of o-CL plasticizes the PLA non-crystalline phase with a more pronounced effect seen as the size of o-CL is reduced. Moreover, it appears that the size of o-CL could also affect the static mechanical properties of the ternary systems as material stiffness and strength reside between those properties measured for high molecular weight PCL/PLA binary blends and the PLA homopolyester. Future work will examine the ability of these blends to sustain these properties during hydrolytic exposure.     

双峰泡孔结构聚苯乙烯材料的制备

以超临界二氧化碳(Sc-CO2)为物理发泡剂,在高压釜中采用两种温度设定方式和降压对聚苯乙烯(PS)进行发泡,测试、分析发泡样品的泡孔结构、泡体密度和断面润湿性能.结果表明,仅通过降压只获得单峰的泡孔结构,而升温与降压协同作用可获得双峰的泡孔结构,大、小泡孔分别在升温和降压阶段成核形成;在发泡温度100℃、饱和温度30~70℃下制备的发泡样品中,大、小泡孔的平均直径分别为50~216和10~15μm.大泡孔的直径较大和密度较高都有利于降低样品的泡体密度,最低达0.15 g/cm3.单峰泡孔结构能在一定程度上提高样品断面的疏水性,使静态接触角(CA)从PS的本征值(87.1°)增大至138.8°;双峰泡孔结构可赋予样品断面更高的CA(155.1°),呈现超疏水特性.     

Copper-catalyzed dehydrogenative cross-coupling reaction between unactivated ethers and simple ketones mediated by pyrrolidine

A copper-catalyzed dehydrogenative cross-coupling reaction between unactivated ethers and simple ketones mediated by pyrrolidine has been developed. Under the catalysis of CuBr₂ and in the presence of pyrrolidine, either tetrahydrofuran 2a or tetrahydropyran 2b can react smoothly with a series of methyl aryl ketones 1a–m to give desired coupling products 3aa–mb using TBHP as an oxidant. The advantages of the dehydrogenative cross-coupling reaction are adoption of unmodified ethers as substrates, good tolerance of many functional groups and use of cheap copper salt as a catalyst. A plausible radical mechanism through enamine attack is proposed.     

Supramolecular organogelators based on Janus type AT nucleosides

J-AT nucleoside-based organogelators 1a and 1b were designed and synthesized. They were endowed with unparalleled superiority to natural nucleobase analogues 2–6 to gelate aromatic solvents due to their excellent self-assembly properties. The J-AT nucleoside-based organogelators showed a specific self-complementary base pair recognition characteristic. The gel stabilities of 1a and 1b were drastically influenced by adenine analogue 2, hardly affected by thymine analogue 3, uracil analogue 4, cytosine analogue 5, and mildly interrupted by guanine analogue 6.     

Transition-metal-free approach to synthesis of indolines from N-(ortho-chloromethyl)aryl amides and iodonium ylides

A transition-metal-free method for the synthesis of indolines has been developed. In the presence of K₂CO₃, the cyclization reaction of N-(ortho-chloromethyl)aryl amides and iodonium ylides proceeded smoothly at room temperature in moderate to good yields.     

Battery-triggered ultrasensitive electrochemiluminescence detection on microfluidic paper-based immunodevice based on dual-signal amplification strategy

Dual-signal amplification strategy for ultrasensitive electrochemiluminescence (ECL) multiplexed immunoassay on microfluidic paper-based analytical devices (μ-PADs) was demonstrated. This dual-signal amplification technique was achieved by employing graphene oxide-chitosan/gold nanoparticles (GCA) immunosensing platform and [4,4′-(2,5-dimethoxy-1,4-phenylene)bis(ethyne-2,1-diyl) dibenzoic acid] (P-acid) functionalized nanoporous silver (P-acid/NPS) signal amplification label. For further low-cost and disposable applications, battery-triggered constant-potential ECL (+1.0 V for P-acid label (vs. Ag/AgCl auxiliary electrode)) was applied on this paper-based immunodevice with the aid of a home-made voltage-tunable power device, allowing the traditional electrochemical workstation to be abandoned. We found that two tumor markers could be sequentially detected in the linear ranges of 0.003–20 and 0.001–10 ng mL⁻¹ with the detection limits down to 1.0 and 0.8 pg mL⁻¹, respectively, by simply reversing the connection mode on two working electrodes. The results exhibited excellent precision and high sensitivity of such immunoassay, and it also demonstrated that this battery-triggered ECL paper-based immunodevice could provide a rapid, simple and simultaneous multiplex immunoassay with high throughput, low-cost and low detection limits for point-of-care testing.