Enantioselective cycloadditions with alpha,beta-disubstituted acrylimides

[reaction: see text] The use of N-H imide templates provides a solution to the problem of rotamer control in Lewis acid catalyzed reactions of alpha,beta-disubstituted acryloyl imides. Reactions proceed through the s-cis rotamer and with improved reactivity because A(1,3) strain is avoided. Enantioselective nitrone, nitrile oxide, and Diels-Alder cycloadditions demonstrate the principle.     

Molecular modeling of quantitative structure retention relationship studies: retention behavior of polychlorinated dibenzofurans on gas chromatographic stationary phases of varying polarity by a novel molecular distance edge vector

Chemical structures of polychlorinated dibenzodioxin (PCDD) congeners are described by a novel molecular distance edge vector (VMDE), developed in our laboratory, that consists of the modified molecular distance edge parameters based on the identical group as a pseudo-atom instead of a traditional atom. Quantitative structure retention relationships (QSRRs) between the new VMDE parameters and the gas chromatographic retention behavior of PCDDs are then generated by a multiple linear regression method for nonpolar, moderately polar, and polar stationary phases. All QSRR models with a high correlation (R > 0.99) are developed for nonpolar, moderately polar, and polar columns (DB-5, SP-2100, SE-54, and OV-1701). Cross validation with the leave-one-out procedure is performed, and satisfactory results are obtained with high correlation. The obtained results show that the new VMDE vector is adapted to characterize the chemical structure and model the retention behavior of PCDDs on various polar stationary phases.     

有机磷化合物的质谱研究：ⅢO—乙基—N_异丙基（取代硫脲基）硫代磷酰胺酯

本文对新合成的19个O-乙基-N-异丙基(取代硫脲基)硫代磷酰胺醋进行了质谱研究。讨论了P—N键的断裂,包括简单断裂和重排反应、失HS·反应及硫脲N上不同取代基的影响等问题。在亚稳态测定和高分辨精确质量测量的基础上得到了这类化合物的断裂规律和质谱特征。     

Guest-responsive polaritons in a porous framework: chromophoric sponges in optical QED cavities

Introducing porous material into optical cavities is a critical step toward the utilization of quantum-electrodynamical (QED) effects for advanced technologies, e.g. in the context of sensing. We demonstrate that crystalline, porous metal–organic frameworks (MOFs) are well suited for the fabrication of optical cavities. In going beyond functionalities offered by other materials, they allow for the reversible loading and release of guest species into and out of optical resonators. For an all-metal mirror-based Fabry–Perot cavity we yield strong coupling (∼21% Rabi splitting). This value is remarkably large, considering that the high porosity of the framework reduces the density of optically active moieties relative to the corresponding bulk structure by ∼60%. Such a strong response of a porous chromophoric scaffold could only be realized by employing silicon-phthalocyanine (SiPc) dyes designed to undergo strong J-aggregation when assembled into a MOF. Integration of the SiPc MOF as active component into the optical microcavity was realized by employing a layer-by-layer method. The new functionality opens up the possibility to reversibly and continuously tune QED devices and to use them as optical sensors.

A phthalocyanine-based porous material in optical cavity exhibited strong coupling and guest responsive polariton feature.     

盐酸黄连素示波电位滴定法的研究

黄连素(小檗碱)是一种重要的抗菌素药,用于治疗细菌性痢疾和一般炎症。现行的分析方法为碘量法,比较烦琐。本文将示波电位滴定法中的金属片电极涂上一层含活性物质的PVC膜,使电极对黄连素等有机药物产生一定的响应,可用于四苯硼酸钠直接滴定黄连素的终点指示。该方法比药典法、直接电位法更简便、直观,易推广使用,同时也扩大了示波电位滴定法的应用范围。     

Morphology and permeability of membranes of polysulfone-graft-poly(tert-butyl acrylate) and derivatives

Polysulfone-graft-poly(tert-butyl acrylate) (PSf-g-PtBA) membranes with PtBA weight fraction ranging from 19.7% to 34% were prepared from the mixing at different ratios of two PSf-g-PtBA samples, which have approximately one PtBA branch per PSf chain but different PtBA chain lengths. PSf-g-PAA membranes, where PAA denotes poly(acrylic acid), were prepared either from the in situ hydrolysis of PtBA in pre-formed PSf-g-PtBA membranes or from casting solutions of PSf-g-PAA. Neutralization of PAA with tetraalkylammonium hydroxide yields PSf-g-P(AA-TAA), where P(AA-TAA) denotes poly(tetraalkylammonium acrylate). Casting solutions of PSf-g-P(AA-TAA) yielded PSf-g-P(AA-TAA) membranes. This paper investigates the variation in the permeability of water and 2-chloroethyl ethyl sulfide (CEES) vapor across the membranes as a function the weight fraction of PtBA, PAA, or P(AA-TAA), where CEES is used as a simulant for the chemical warfare agent sulfur mustard bis(2-chloroethyl) sulfide. Also presented are the TEM images of thin sections of the different membranes revealing the morphology of the PtBA, PAA, and P(AA-TAA) domains.     

3D-CE-TOF-SPGR对静脉性颅神经血管压迫综合征的应用

探讨3D-CE-TOF-SPGR序列在诊断静脉性颅神经血管压迫综合征中的临床应用价值。研究对象为我院收治的经手术证实且行磁共振断层血管成像(MRTA)检查的198例中7例静脉性颅神经血管压迫综合征患者,并与微血管减压术(MVD)中所见进行对照,其中原发性三叉神经痛5例、面肌痉挛2例。MRTA包括3D-FIESTA、3D-TOF-SPGR和3D-CE-TOF-SPGR序列,颅神经受压与责任静脉血管3D-FIESTA序列显示1例、3D-TOF-SPGR序列显示1例、3D-CE-TOF-SPGR序列显示6例,独立应用3D-CE-TOF-SPGR序列显示能力最佳(6/7,85.71%)。因此,MRTA成像技术中,3D-CE-TOF-SPGR序列能清楚显示目标颅神经及相应颅神经受压的静脉性责任血管,对指导临床MVD手术具有重要价值。     

Facile deacylation of N-acyl-2,3-dihydrobenzo-1,4-thiazine 1-oxide and 1,1 dioxide

The title amides react easily with methanolic sodium methoxide at room temperature affording 2,3-dihydrobenzo-1,4-thiazine 1-oxide and 1,1-dioxide and methylacetate. An unusual mechanism of deacylation is proposed.     

超细碳化钨及其复合粉末的制备

超细碳化钨(WC)是近年发展起来的硬质合金材料，本文根据超细碳化钨粉末在还原碳化过程中是否连续，将其制备方法分成一步法和两步法进行综述。同时，归纳了超细WC-Co复合粉末的主要制备方法，其中喷雾干燥-流化床法具有操作过程连续、复合粉与反应气体接触充分、复合粉末的活性高、反应温度低和最终粉末的晶粒细小均匀等优点，可望作为制备超细碳化钨及其复合粉末的重要方法。     

Simultaneous determination of six alkaloids in tobacco and tobacco products by direct analysis of real‐time triple quadrupole mass spectrometry with a modified pretreatment method

In order to determine six alkaloids (mass fraction) of nicotine, nornicotine, myosmine, anatabine, anabasine, and nicotyrine in tobacco and tobacco products quickly, accurately, and simultaneously, a novel method based on direct analysis of real‐time model in situ ionization technique combined tandem mass spectrometry with a modified sample pretreatment was established, in which experimental parameters such as the type and amount of extraction solvent and injection rate were optimized, respectively. The samples of five commercial cigarettes and five kinds of tobacco leaves were analyzed by the established method, and the determined values were compared with those obtained using a gas chromatography with mass spectrometry method: (1) Under optimized conditions (30 mL ultrapure water as extraction solvent and with extraction rate of 0.6 mm/s), analysis could be completed within 10 min. (2) The linear range of the method was 0.002–2000 μg/g with, the recovery ranged from 86.8 to 105.6%, and the limit of detection and the limit of quantification were 0.004–0.835 μg/g and 0.013–2.787 μg/g, respectively. (3) The relative standard deviation between direct analysis of real‐time method and the gas chromatography with mass spectrometry method was 0.34–8.83%. The established method is rapid, reliable, and suitable for the ultrafast determination of six alkaloids in tobacco and tobacco products.