铂电极响应非电对离子的机理研究(Ⅱ)

预处理的铂电极对一系列金属离子Ｍ＾２＋活度阶梯变化的响应都是非单一突跃型瞬时信号。提出了离子交换反应历程,认为离子水合吉氏自由能－ΔＧ＾０ｈ（Ｍ＾２＋）相当于离子交换反应的活化能。用离子交换过程ΔＧ＾－ｈ（Ｐ＾２＋ｔ）与ΔＧ＾０ｈ（Ｍ＾２＋）之差合理地解释了不同离子瞬时信号峰高的次序。证明电极瞬时电位不是决定于离子扩散速度而是决定于离子交换速度。     

工业Mo-Ni/USY-Al_2O_3失活催化剂的再生行为

用ESCA ,XRD ,SEM及TPR等手段表征了不同条件下再生的工业失活加氢裂化催化剂 .结果表明 ,Mo Ni/USY Al2 O3 失活催化剂在实验室装置中快速再生优于慢速再生 ;再生温度对催化剂的结构与性能有影响 .480℃再生能将失活催化剂中绝大部分的碳和氮烧掉 ,且比表面积恢复率最高 ;6 0 0℃再生时 ,催化剂的毛细孔口明显减少 ,且产生少量聚结态 β NiMoO4 晶相     

Determination of bisphenol A, 4‐octylphenol,and 4‐nonylphenol in soft drinks and dairy products by ultrasound‐assisted dispersive liquid–liquid microextraction combined with derivatization and high‐performance liquid chromatography with fluorescence detection

A novel hyphenated method based on ultrasound‐assisted dispersive liquid–liquid microextraction coupled to precolumn derivatization has been established for the simultaneous determination of bisphenol A, 4‐octylphenol, and 4‐nonylphenol by high‐performance liquid chromatography with fluorescence detection. Different parameters that influence microextraction and derivatization have been optimized. The quantitative linear range of analytes is 5.0–400.0 ng/L, and the correlation coefficients are more than 0.9998. Limits of detection for soft drinks and dairy products have been obtained in the range of 0.5–1.2 ng/kg and 0.01–0.04 μg/kg, respectively. Relative standard deviations of intra‐ and inter‐day precision for retention time and peak area are in the range of 0.47–2.31 and 2.76–8.79%, respectively. Accuracy is satisfactory in the range of 81.5–118.7%. Relative standard deviations of repeatability are in the range of 0.35–1.43 and 2.36–4.75% for retention time and peak area, respectively. Enrichment factors for bisphenol A, 4‐octylphenol, and 4‐nonylphenol are 170.5, 240.3, and 283.2, respectively. The results of recovery and matrix effect are in the range of 82.7–114.9 and 92.0–109.0%, respectively. The proposed method has been applied to the determination of bisphenol A, 4‐octylphenol, and 4‐nonylphenol in soft drinks and dairy products with much higher sensitivity than many other methods.     

糖类衍生物在毛细管区带电泳下的分离研究

以新合成的1-萘基-3-甲基-5-吡唑啉酮(NMP)为柱前衍生试剂,采用毛细管区带电泳模式考察并优化了糖类衍生物的分离条件。实验采用58.5cm×50μmi.d.毛细管(有效柱长50cm),55mmol/L硼酸盐缓冲溶液(pH9.46),柱温20℃,分离电压22kV,进样10s,在不加任何添加剂的情况下,高效、快速地实现了9种糖的基线分离,并在最优化条件下进行了唐古特白刺实际样品的分离分析,结果令人满意。     

Tumor‐Exocytosed Exosome/Aggregation‐Induced Emission Luminogen Hybrid Nanovesicles Facilitate Efficient Tumor Penetration and Photodynamic Therapy

The development of novel photosensitizing agents with aggregation‐induced emission (AIE) properties has fueled significant advances in the field of photodynamic therapy (PDT). An electroporation method was used to prepare tumor‐exocytosed exosome/AIE luminogen (AIEgen) hybrid nanovesicles (DES) that could facilitate efficient tumor penetration. Dexamethasone was then used to normalize vascular function within the tumor microenvironment (TME) to reduce local hypoxia, thereby significantly enhancing the PDT efficacy of DES nanovesicles, and allowing them to effectively inhibit tumor growth. The hybridization of AIEgen and biological tumor‐exocytosed exosomes was achieved for the first time, and combined with PDT approaches by normalizing the intratumoral vasculature as a means of reducing local tissue hypoxia. This work highlights a new approach to the design of AIEgen‐based PDT systems and underscores the potential clinical value of AIEgens.     

Daphnilongerine, an unprecedented fused pentacyclic ring system alkaloid from Daphniphyllum longeracemosum Rosenth.

An unusual yuzurine-type alkaloid daphnilongerine (1), with an unprecedented fused pentacyclic skeleton in addition to seven known ones, daphnigracine (2), daphnezomine R, daphnigraciline, yuzurine, longistylumphyllines A, daphnilongeranin C, and calycinine A, was isolated from the fruits of Daphniphyllum longeracemosum. The structure and relative stereochemistry of 1 were determined by spectroscopic analysis.     

(3R,5R)-3,5-二羟基-6-取代己酸不对称合成研究进展

概述近 2 0年来 ( 3R ,5R) 3 ,5 二羟基 6 取代己酸不对称合成进展 ,并提出其研究方向 .     

Sulfamic acid as a cost-effective catalyst instead of metal-containing acids for acetolysis of cyclic ethers

Sulfamic acid has been used as an efficient catalyst and green alternative for metal-containing acidic materials to promote the acetolysis reaction of THF to produce 1,4-diacetoxybutane. This method is also applicable to the acetolysis of other cyclic ethers, such as methyl substituted THF and tetrahydropyran and 1,4-dioxane, which is less reactive.     

Eremophilane Sesquiterpenes from Cacalia Roborowskii

Themajorityofphytochemicalstudiesonsenencioneace(compositae)specieshavebeenconcentratedonthepyrrolizidinealkaloidsandsesquiteIPenesbecauseoftheirpotentialbioactivitiesandCytotoalcactivities.lCacaliaroborowskii(maxim)LinginslongbeenusedasfolkremedyinnorthwestemChina.Recently,wehadisolatedseveralneweremophilenolides'fromtherootsofthisplant.Asacontinuahonofourinvestigationontillsspecies,wenowpresenttileisolationandsmicturalelucid.ltionoffouraddihonalneweremophilanesesquiterpenes.Theirsmicturesw…     

Separation and determination of flavone and xanthone glycosides in Tibetan folk medicinal species Swertia mussotii and S. franchetiana by capillary electrophoresis

The contents of five pharmacologically active flavone and xanthone glycosides, namely, swertianolin, swertisin, isoorientin, mangiferin, and 7-O-[α-L-rhamnopyranosyl-(1 → 2)-β-D-xylopyranosyl]-1,8-dihydroxy-3-methoxyxanthone, extracted from Tibetan folk medicinal species Swertia mussotii and S. franchetiana were determined by capillary electrophoresis with diode-array detection. The separation of five components has been optimized with a capillary column with a total length of 48.5 cm and effective length of 40 cm (50 μm i.d). The influence of the running buffer, the sodium dodecyl sulfonate (SDS) concentration, organic modifier, etc. on the resolution was evaluated. The background electrolyte contained 30 mM borate buffer, 28 mM SDS, 1.0% (v/v) acetonitrile, and was adjusted to pH 9.0 with 0.1 M NaOH. A good baseline resolution was obtained for the separation of five components within 5 min with the working voltage of 24 kV and a column temperature of 25°C. The established method was rapid and reproducible for the separation and determination of five flavone and xanthone glycosides from the extracts of S. mussotii and franchetiana plant samples. The text was submitted by the authors in English.