银络合物在催化核上的还原反应

研究了尿嘧啶银络合物在胶态金属及其硫化物核上被对苯二酚还原的反应，并以Ａｇ和Ｐｔ电极代替催化核与对苯二酚显影剂和银络合物组成原电池作为电化学模型，分别测定该络合物阴极反应和对苯二酚阳极反应的电流。结果表明，原电池的电流大小与反应速度成正比关系，从而为物理显影电极理论提供实验依据。     

Polyelectrolyte microcapsules templated on poly(styrene sulfonate)-doped CaCO3 particles for loading and sustained release of daunorubicin and doxorubicin

A strategy to incorporate and release anti-cancer drugs of daunorubicin (DNR) and doxorubicin (DOX) in preformed microcapsules is introduced, which is based on charge interaction mechanism. Oppositely charged poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) were assembled onto PSS doped-CaCO₃ colloidal particles in a layer-by-layer manner to yield core-shell particles. After removal of the carbonate cores, hollow microcapsules with entrapped PSS were fabricated, which showed spontaneous loading ability of positively charged DNR and DOX. The drug loading was confirmed quantitatively by observations under confocal laser scanning microscopy, transmission electron microscopy and scanning force microscopy. Quantification of the drug loading was performed under different conditions, revealing that a larger amount of drugs could be incorporated at higher drug feeding concentrations and higher salt concentrations. However, putting additional polyelectrolyte layers on the microcapsules after core removal resulted in weaker drug loading efficiency. The drug release behaviors from the microcapsules with different layer numbers were studied too, revealing a diffusion controlled release mechanism at the initial stage (4 h).     

Preparation and evaluation of a large-volume radial flow monolithic column

In this study, a 38 mL monolith with homogeneous porous structure was produced by a single polymerization from glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) in the presence of porogens and an initiator. The uniform temperature distribution within the reaction system was achieved by adding reactant mixture continuously and enhancing the heat transfer ability of the polymerization system. Homogeneous porous structure in the monolith was proved by SEM and the pore size distribution profiles measured by mercury intrusion porosimetry. Experimental results from proteins separation indicated that the dynamic capacity and resolution of radial flow monolithic column were independent of flow rates. Furthermore, the pressure drop on the column was linearly dependent on the flow rate and did not exceed 1.7 MPa even at a flow rate of 50 mL/min, which proved that the prepared monolith could be used in the quick separation and preparation of biopolymers.     

Comparison of standard addition and conventional isotope dilution mass spectrometry for the quantification of endogenous progesterone in milk

In this study, a standard addition–isotope dilution mass spectrometry (SA-IDMS) method for quantification of endogenous progesterone in milk has been described. The method validation results, linearity, limits of detection and quantification, recovery and uncertainty were fit for the purpose of assigning reference mass fractions to proficiency testing schemes. The developed technique was compared to the isotope dilution mass spectrometry (IDMS) method already existing in the laboratory. Analytical results of two milk samples were (1.377 ± 0.048) μg/kg and (4.457 ± 0.155) μg/kg by SA-ID-LC/MS method, while the results were (1.355 ± 0.019) μg/kg and (4.359 ± 0.059) μg/kg by ID-LC/MS, respectively. Since SA-IDMS was an effective quantitative method that overcame matrix effect, similar quantitative results from IDMS and SA-IDMS indicated that the quantification of progesterone in milk was barely influenced by matrix. Both IDMS and SA-IDMS could be used to assign reference mass fractions to progesterone in milk inter-laboratory proficiency testing schemes.     

High-efficiency α-benzoyloxylation and hydroxylation of β-keto amides by phase transfer catalysis

A facile and efficient protocol for α-benzoyloxylation and α-hydroxylation of β-keto amides by phase-transfer catalysis is presented. This methodology provides mild and practical access to a variety ofα-oxygenated β-keto amides. Furthermore, α-benzoyloxylation products can be easily converted into α-hydroxylation compounds, which are useful synthetic precursors of biological targets.     

Validation of an LC-MS/MS method for the quantitative determination of a novel fungicide: pyraoxystrobin in rat plasma and its application to a toxicokinetics study

A simple, sensitive, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of pyraoxystrobin in rat plasma and applied to a toxicokinetics study. The separation was performed by gradient elution on a Luna 5 μ C18 (2) 100 Å column (50?×?4.6 mm I.D., 5 μm) with mobile phase: water (0.1 % formic acid, v/v)/acetonitrile (0.1 % formic acid, v/v), followed by quantification with a mass detector in multiple reaction monitoring (MRM) mode using ESI as an interface. The calibration curve was linear over a concentration range of 1.00–200 ng/mL. The recovery for pyraoxystrobin ranged from 101.4 to 108.2 %. The intraday bias and precision ranged from ?9.3 to 8.1 % and from 0.7 to 8.4 %, respectively, and the interday bias and precision ranged from ?0.3 to 4.0 % and from 4.4 to 7.2 %, respectively. The toxicokinetics of pyraoxystrobin after single 100 and 1,000 mg/kg oral doses were studied in rats. Figure

The chromatogram of pyraoxystrobin highest calibration standard (ULOQ) extract.     

铱单原子和纳米粒子在N2O分解反应中的协同催化

原子捕获法是在高温条件下制备高热稳定单原子催化剂的有效方法之一. 但该方法制备的单原子催化剂通常面临着催化活性低、 反应适用范围窄的问题. 因此, 拓展这类单原子催化剂的应用是亟待解决的难点. 本文采用高温捕获法制备的铱(Ir)单原子催化剂在氮氧化物分解反应中的催化活性较低, 但是在继续负载纳米粒子后, 单原子与纳米粒子之间表现出显著的协同催化作用. X射线光电子能谱(XPS)和CO吸附的原位漫反射红外光谱(CO-DRIFTs)表征结合反应动力学分析揭示了反应的活性中心是金属态的Ir纳米粒子. 虽然氧化态的Ir单原子不能直接活化N₂O分子, 但是可以改变Ir纳米粒子的电子结构和吸附性能. 氧气程序升温脱附(O₂-TPD)实验证实, 单原子的存在可以促进O₂从Ir纳米粒子上脱附, 从而提高催化剂的反应活性.     

高效液相色谱-二极管阵列检测法测定小麦粉及面粉改良剂中福美双

福美双是重要的二硫代氨基甲酸酯(DTC)杀菌剂,在小麦中使用限量以1 mg/kg二硫化碳(CS₂)计。目前我国相关检测方法是针对二硫代氨基甲酸酯一类的化合物,二硫代氨基甲酸酯通过与酸反应生成CS₂,采用光谱法或色谱法测定CS₂,间接实现二硫代氨基甲酸酯测定。该方法无法特异性实现对福美双的检测,因此开展小麦粉中福美双检测方法的研究具有重要意义。研究建立了高效液相色谱-二极管阵列检测(HPLC-DAD)测定小麦粉及面粉改良剂中福美双的分析方法。小麦粉及面粉改良剂样品用乙腈溶剂提取后,经涡旋、振荡、冰水浴超声和静置后取上清液过滤,供高效液相色谱测定。采用ZORBAX plus-C18色谱柱(150 mm×4.6 mm, 5 μm)分离,以水-乙腈为流动相洗脱分析,在波长280 nm下检测。实验优化了提取溶剂及其体积、振荡超声条件、色谱柱、检测波长、流动相等条件。该方法采用保留时间和紫外光谱图定性,外标法定量。该方法在线性范围内(0.30~30.0 μg/mL)线性关系良好,相关系数(r²)为0.99999。对小麦粉及面粉改良剂进行1.5、3.0、15 mg/kg 3个水平的加标回收试验,福美双的回收率为89.6%~98.3%,相对标准偏差为1.6%~3.9%(n=6)。方法的检出限和定量限分别为0.5 mg/kg和1.5 mg/kg。该方法采用溶剂提取,操作简单,分析时间短,特异性好,具有精密度高、重复性好、检出限低等特点,适用于小麦粉及面粉改良剂中福美双快速、准确的定量检测。     

Nucleophilic Difluoromethylation of Epoxides with PhSO(NTBS)CF2H by a Preorganization Strategy

Unlike the facile synthesis of β‐monofluoromethyl alcohols by nucleophilic monofluoromethylation of epoxides, the synthesis of β‐difluoromethyl alcohols by nucleophilic difluoromethylation of epoxides still remains a challenge. Herein, studies on tackling this problem with PhSO(NTBS)CF₂H ( 2 ; TBS=tert‐butyldimethylsilyl) are reported. The preorganization of 2 and epoxides with BF₃ ? Et₂O was found to be crucial for the reaction. The reaction shows excellent regioselectivity and has a broad substrate scope. The facile transformation of the ring‐opened products to β‐difluoromethyl, γ‐difluoromethyl, and β‐difluoromethylenyl alcohols demonstrates the synthetic utility of the reaction.     

Unsymmetrical N and/or O-bridged calixarene derivatives: synthesis,structure and encapsulation of solvent molecules in the solid state

Eight unsymmetrical N and/or O-bridged calixarene derivatives were obtained by 1 (naphthalene-2,7-diol), 2 (bis(4-hydroxyphenyl)methanone), 3 (4,4′-methylenedianiline), 4 (3,3′-methylenedianiline), 5 (4,4′-oxydianiline) and 6 (4,4′-(perfluoropropane-2,2-diyl)dianiline) reacting with fragment a (4,4′-bis(dichloro-s-triazinyloxy)propane-2,2-diyldibenzene) and b (N,N′-bis(dichloro-s-triazinyl)-4,4′-methylenedianiline) under very mild reaction conditions via efficient fragment coupling strategy. We also obtained the crystal structure of 1a (tetraoxocalix[2](propane-2,2-diyldibenzene,naphthalene)[2]triazine) which can form a molecular capsule by two dimers with C–H?N and C–H?O quadruple hydrogen bonds, and it has the encapsulation ability toward solvent molecules.