原位漫反射傅里叶变换红外光谱研究锰铁基催化剂上低温选择性催化还原反应机理简

采用自蔓延燃烧法制备了Ti_0.9Mn_0.05Fe_0.05O_2-δ催化剂,运用原位漫反射傅里叶变换红外光谱对该催化剂的NO和NH₃稳态吸附以及NO和NH₃瞬态反应进行了详细地分析与讨论. 结果表明,相比于Lewis酸性位,150℃时Brönsted酸性位吸附的NH₃更具有SCR活性;与双齿硝酸盐和桥式硝酸盐相比,NO吸附产生的单齿硝酸盐是主要的中间物种;该SCR反应遵循Eley-Rideal和Langmuir-Hinshelwood机理,但以后者为主. 另外,O₂的存在有利于NO的氧化和配位态NH₃的活化.     

pH-Sensitive Wettability Induced by Topologicaland Chemical Transition on the Self AssembledSurface of Block Copolymer简

pH-sensitive wettability of polystyrene-b-poly（4-vinylpyridine） （PS-b-P4VP） self assembled films, exhibiting superoleophobicity under water and hydrophilicity at low pH value, and oleophobicity under water and hydrophobicity at neutral condition, has been realized. The wettability properties resulted from the surface topological and chemical transition, which were confirmed by in situ AFM measurements under water at different pH. At low pH, P4VP chains, which were confined in the hexagonal-packed nanodomains, got protonated into a swollen state, while at high pH, P4VP chains were deprotonated into a collapsed state. The reversible protonation/deprotonation procedure on the molecular scale leads to surface topological and chemical transition, thereby pH-sensitive wettability.     

Mass Transfer Analysis of Growth and Substance Metabolism of NSCs Cultured in Collagen-Based Scaffold In Vitro

The aim of this study is to analyze the growth and substance metabolism of neural stem cells (NSCs) cultured in biological collagen-based scaffolds. Mass transfer and metabolism model of glucose, lactic acid, and dissolved oxygen (DO) were established and solved on MATLAB platform to obtain the concentration distributions of DO, glucose, and lactic acid in culture system, respectively. Calculation results showed that the DO influenced their normal growth and metabolism of NSCs mostly in the in vitro culture within collagen-based scaffolds. This study also confirmed that 2-mm thickness of collagen scaffold was capable of in vitro cultivation and growth of NSCs with an inoculating density of 1?×?10⁶ cells/mL.     

离子液体在锂离子电池中的应用研究进展

离子液体具有蒸汽压低、热稳定性好、不易挥发、溶解能力强、环境友好、电化学稳定窗口和液程范围宽等优点,在锂离子电池领域应用前景广泛。本文按照离子液体作为电解质溶剂、与传统电解质复配或与聚合物电解质结合的应用方式,总结其对电池的安全性和热稳定性的影响,并综述了近年来离子液体在锂离子电池电解质中的应用研究进展。     

泡沫塑料富集–石墨炉原子吸收光谱法测定贝类水产品中痕量铊

采取微波消解的前处理手段消解样品,经泡沫塑料分离富集后,用石墨炉原子吸收光谱法测定贝类水产品中痕量铊。以1.5 mL Fe3+,2 mL H2O2和5%王水介质作为吸附体系将样品中铊分离富集,再以硝酸钯、抗坏血酸作为基体改进剂进行测定。铊的质量浓度在0～50μg/L范围内线性良好,相关系数为0.999 7,方法的检出限可达0.07μg/g。测定结果的相对别准偏差为1.53%～4.01%(n=7),加标回收率为87.1%～98.3%。泡沫塑料富集–石墨炉子吸收光谱法测定贝类水产品中痕量铊是一种准确、安全、便捷的检测方法。     

Cu Nanoparticles Embedded in N‐Doped Carbon Materials for Oxygen Reduction Reaction

Development of eco‐friendly, cost‐effective, and high‐performance electrocatalysts to replace precious metal platinum for oxygen reduction reaction (ORR) has received increasing attention. Herein, we adopt a facile one‐pot strategy to embed Cu nanoparticles onto N‐doped carbon‐graphene (Cu@NC‐700). The Cu@NC‐700 exhibits robust and efficient ORR catalysis with positive half‐wave potential (~0.86 V vs. RHE) and low Tafel slope (33.9 mV?dec^–1) in 0.1 M KOH solution. Meanwhile, it manifests remarkable electrochemical stability, and strong tolerance to methanol crossover and carbon monoxide poisoning. The synergistic effect between Cu‐N‐C sites, Cu nanoparticles, and N‐doped carbon support speeds up ORR electrocatalysis.     

Synthesis of carbon dots with a tunable photoluminescence and their applications for the detection of acetone and hydrogen peroxide

Carbon dots(CDs) with multi-color emissive properties and a high photoluminescent quantum yield(PLQY) have attracted great attention recently due to their potential applications in chemical,environmental,biological and photo-electronic fields.Solvent-dependent effect in photoluminescence provides a facial and effective approach to tune the emission of CDs.In this study,green emissive nitrogen-doped carbon dots(N-CDs) are synthesized from p-hydroquinone and ethylenediamine through a simple hydrothermal method.The as-prepared N-CDs possess a robust excitation-independent green luminescence and a high PLQY of up to 15.9%.Further spectroscopic characterization indicates that the high PLQY is achieved by the balance of nitrogen doping states and the surface passivation extent in CDs.The N-CDs also exhibit solvent-dependent multi-color emissive property and distinct PLQY in different solvents(the maximum can reach up to 25.3%).Furthermore,the as-prepared N-CDs are applied as fluorescence probes to detect acetone and H2O2 in water.This method has exhibited a low detection limit of acetone(less than 0.1 %) and a quick and linear response to the H_2O_2 with the concentration from 0 to 120 μmol/L.This work broadens the knowledge of applying CDs as probes in the bio and chemical sensing fields.     

二茂铁骨架系列三齿配体的合成及其在铱催化不对称氢化中的应用

本文主要介绍了一系列基于二茂铁骨架的三齿配体:f-amphox、f-ampha、f-amphol和f-amphamide的合成及其应用。这四类手性膦氮配体的铱络合物可以高活性(TON高达1 000 000)、高转化率(>99%)、高对映选择性(>99% ee)地催化(官能团化)酮等底物的不对称氢化反应。该系列配体成功地应用于地诺帕明、苯福林和沙丁胺醇等手性医药中间体的不对称合成。与传统路线相比,这些合成方法更高效,副产物更少,“三废”排放量更低。     

Controllable Si−C Bond Activation Enables Stereocontrol in the Palladium‐Catalyzed [4+2] Annulation of Cyclopropenes with Benzosilacyclobutanes

A novel and unusual palladium‐catalyzed [4+2] annulation of cyclopropenes with benzosilacyclobutanes is reported. This reaction occurred through chemoselective Si?C(sp²) bond activation in synergy with ring expansion/insertion of cyclopropenes to form new C(sp²)?C(sp³) and Si?C(sp³) bonds. An array of previously elusive bicyclic skeleton with high strain, silabicyclo[4.1.0]heptanes, were formed in good yields with excellent diastereoselectivity under mild conditions. An asymmetric version of the reaction with a chiral phosphoramidite ligand furnished a variety of chiral bicyclic silaheterocycle derivatives with good enantioselectivity (up to 95.5:4.5 er). Owing to the mild reaction conditions, the good stereoselectivity profile, and the ready availability of the functionalized precursors, this process constitutes a useful and straightforward strategy for the synthesis of densely functionalized silacycles.     

Benzophenone glycosides from the pericarps of Aquilaria yunnanensis S. C. Huang

Abstract

Two new benzophenone glycosides, aquilarisides A (1) and B (2), together with six known analogues (3-8) were isolated from the pericarps of Aquilaria yunnanensis S. C. Huang. Their structures were elucidated on the basis of 1D and 2D NMR and mass spectroscopic analyses, and the absolute configuration of compound 1 was determined by experimental and calculated electronic circular dichroism (ECD) spectra. Anti-inflammatory activities of all compounds 1–8 were evaluated for their inhibitory activities against lipopolysaccharide (LPS)-stimulated induced nitric oxide (NO) production in RAW 264.7 cells using the Griess assay. Compound 2 indicated a weak inhibition of NO production.