溶剂/流速双梯度-HPLC整体柱分析三七中药配方颗粒中4种皂苷成分

建立一种新的溶剂/流速双梯度-整体柱高效液相色谱法快速测定三七中药配方颗粒中4种皂苷成分. 通过乙腈浓度、流速与被测物的lg k线性相关性, 预测被测组分三七皂苷R₁, 人参皂苷Rg₁与人参皂苷Re的适宜k值, 以测得的分离度为优化指标, 建立分离R₁, Rg₁, Re的最佳分离模式1和2|在此基础上, 通过考察乙腈浓度和流速随时间的变化率对分离人参皂苷Rb₁的影响, 以Rb₁与相邻杂质的分离度为优化指标, 得到分离R₁, Rg₁, Re, Rb₁的两种最佳模式. 应用色谱优化函数(COF)作为综合指标评价, 结果显示模式2优化效果更好. 采用模式2的色谱条件, 20 min内完成对三七配方颗粒中4种皂苷成分的质量分析, 结果表明该方法准确可行、快速.     

Hemin-Promoted Direct C−H Thiolation in the Synthesis of Diaryl Sulfides

Diaryl sulfides are a class of important synthetic chemical units. Herein, we report a new method for direct preparation of diphenyl sulfides using P-toluenesulfonyl chloride as an effective thiophenyl radical precursor with assistance from Hemin. Various substituted anisoles and benzenesulfonyl chlorides are well tolerated, resulting in moderate to good yields of diaryl sulfides. The potential of the proposed method is validated by good yields obtained in gram scale reactions.     

Ga(OTf)3-catalyzed Three-component Mannich Reaction in Water Promoted by Ultrasound Irradiation

Ga(OTf)₃‐catalyzed three‐component Mannich reaction of aromatic aldehydes, aromatic amines and cycloketones in water promoted by ultrasound gave the corresponding β‐amino cycloketones in good to excellent yields and good anti selectivities.     

Toxic effect of triphenyltin chloride on the alga Spirulina subsalsa

A previous study on the deleterious effect of triphenyltin chloride (TPTCl) on the alga Spirulina subsalsa reported on four physiological and biochemical indices (or parameters): growth rate, chlorophyll content, phycocyanin content and nitrate reductase activity. In the present study, further research was performed to confirm the findings reported in the previous paper, using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM images show significant changes in the screw‐pitch of S. subsalsa, suggesting that TPTCl may damage the inheritance characteristics of S. subsalsa. The TEM images illustrate that the external pectin theca, limiting membrane and inter photosynthetically active lamella in the S. subsalsa cell are those targets that can be easily damaged. Reversible and irreversible cell damage (cell necrosis) are also observed. Copyright © 2002 John Wiley & Sons, Ltd.     

Liquid-phase oxidation of toluene to benzaldehyde with molecular oxygen catalyzed by copper nanoparticles supported on graphene

Highly-dispersed copper nanoparticles (Cu NPs) were fabricated on the surface of reduced graphene oxide via direct hydrazine hydrate reduction of Cu²⁺ in aqueous solution. Scanning electron microscope and transmission electron microscope images show that the Cu NPs are distributed on the surface of graphene nanosheets, and the average particle size was about 40 nm. The Cu NPs supported on graphene have high reaction activity for the oxidation of toluene to corresponding benzaldehyde. It was found that the selectivity reached 66.5% and the conversion of toluene reached 11.5%.     

Promoted colorimetric response of spirooxazine derivative: a simple assay for sensitive mercury(II) detection

Research on Chemical Intermediates - A spirooxazine derivative 1,3-dihydro-1,3,3-trimethyl-spiro[2-H-indole-2-2′-[2H-1,4] oxazino [2,3-f] [1, 10] phenanthroline] (compound 1) was explored as...     

Titanium carbonitride films on cemented carbide cutting tool prepared by pulsed high energy density plasma

Hard films prepared by pulsed high energy density plasma (PHEDP) are characterized by high film/substrate adhesive strength, and high wear resistance. Titanium carbonitride (TiCN) films were deposited onto YG11C (ISO G20) cemented carbide cutting tool substrates by PHEDP at room temperature. XRD, XPS, SEM, AES, etc. were adopted to analyze the phases (elements) composition, microstructure and the interface of the films, respectively. The results show that, the uniform dense films are composed of grains ranging from 70 to 90 nm. According to the AES result, there is a broad transition layer between the film and the substrate, due to the ion implantation effect of the PHEDP. The transition layer is favorable for the film/substrate adhesion.     

由因式化L算子所构成的经典可积动力学体系

用因式化的L算子构造了一类在非周期边界条件下的可积模型.对体系的transfer矩阵取三角和标度极限情况下,得到了n维体系(n为奇数)的经典哈密顿量的具体形式.结果表明,这类可积体系与Calogero等人所发现的一系列可积体系是相类似的.     

STUDIES ON HIGH SOLID CONTENT AND STABLEEMULSIFIER-FREE EMULSION POLYMERIZATION

1.INTRODUCTIONEmulsifier-freeemulsionpolymerizationhasrecentlyreceivedmoreandmoreattentionduetoitsacademicandpracticalinterest.Latexesofmono-disperseandcleanthatwithoUtremovablesurfactantcanbeobtained.Inaddition,materialsofhigheradhesionandwaterresistancecanbeprepared.Especially,itcanavoidfromenvironmentalpollution.UPtodate,emulsifier-freeemulsionpolymeriZationismainlypreparedbyintroducingionicinitiators,*.Towhomcorrespondenceshouldbeaddressedamphiphilicoligomers,hydrophilic,nonionicori…