侧基差异对聚乙烯基衍生物特性黏数和极性的影响

基于改进的构象-构型统计方法,推导了计算均方电偶极矩和均方回转半径的通用公式,应用于研究侧基的结构和极性对聚乙烯醇(PVA),聚乙烯基甲基醚(PVME)和聚醋酸乙烯酯(PVAc)等链物理性质的影响.计算得到其全同链均方电偶极矩特征比分别为2.51、2.15和1.39,间同链温度系数差异达到5.68×10-3K-1,并且均方电偶极矩与侧基极性的方向和链构型、均方回转半径与侧基尺寸和柔性有明显相关性.通过比较特征比对构象能的微分值,发现PVA、PVAc和PVME侧基的相互作用能对特征比的影响比聚乙烯吡硌烷酮的影响更大,如PVME微分值可达到-81.2×10-2mol/J.通过对照特性黏数,观察到聚丙烯酸甲酯的值比PVAc的值更为多变.     

Quantitative analysis of costunolide and dehydrocostuslactone in rat plasma by ultraperformance liquid chromatography–electrospray ionization–mass spectrometry

Costunolide and dehydrocostuslactone are well‐known sesquiterpene lactones contained in many plants used as popular herbs, such as Saussurea lappa and Laurus novocanariensis, and have been considered as potential candidates for the treatment of various types of tumor. In the present work, a sensitive UPLC‐MS/MS for the quantification of costunolide and dehydrocostuslactone in biological matrices has been developed. The method is based on protein precipitation with acetonitrile followed by isocratic ultraperformance liquid chromatographic separation using methanol–formic acid (0.1% in water; 70:30, v/v) mobile phase. Detection was performed by ESI mass spectrometry in MRM mode with the precursor‐to‐product ion transitions m/z 233–187 and m/z 231–185, respectively. The calibration curves of analytes showed good linearity within the established range 0.19–760 ng/mL for costunolide and 0.23–908 ng/mL for dehydrocostuslactone. The lower limits of quantification of costunolide and dehydrocostuslactone were found to be 0.19 and 0.23 ng/mL, respectively. The intra‐day and inter‐day presicions of this method for the entire validation were less than coefficient of variation of 7% and the accuracy was within ±8% (relative error). The mean extraction recoveries were 73.8 and 75.3%, respectively. The method was found to be precise, accurate and specific during the study, and was successfully used to analyze the pharmacokinetics of costunolide and dehydrocostuslactone. Copyright © 2010 John Wiley & Sons, Ltd.     

Picosecond pulse of variable duration by phase matching frequency doubling crystal

Report on a semiconductor saturable absorber mirror (SESAM) passively mode-locked picosecond Nd:YVO₄ laser, with adjustable durations between 8.7 and 70 ps. The pulse duration was adjustable by varying the length of type II phase matching KTiOPO₄ (KTP) crystal. Type II phase matched second harmonic interaction in combination with the anisotropic emission characteristic of Nd:YVO₄ introduced additional bandwidth limiting through birefringent filtering.     

NMR spectroscopic studies on the mechanism of cellulose dissolution in alkali solutions

It was considered that the dissolution of cellulose in alkali solutions is mainly due to the breakage of hydrogen bonds. As an alkali hydroxide, KOH can provide OH^? just like LiOH and NaOH; but it is well known that LiOH and NaOH can dissolve cellulose, whereas KOH can only swell cellulose. The inability of KOH to dissolve cellulose was investigated and the mechanism of cellulose dissolving in alkali solutions was proposed. The dissolution behavior of cellulose and cellobiose in LiOH, NaOH and KOH were studied by means of ¹H and ¹³C NMR as well as longitudinal relaxation times. The structure and properties of the three alkali solutions were compared. The results show that alkali share the same interaction mode with cellobiose and with the magnitude of LiOH > NaOH > KOH; the alkalis influence the structure of water also in the same order LiOH > NaOH > KOH. The different behavior of the three alkalis lies in the different structure of the cation hydration ions. Li⁺ and Na⁺ can form two hydration shells, while K⁺ can only form loose first hydration shell. The key to the alkali solution can or cannot dissolve cellulose is whether the cation hydration ions can form stable complex with cellulose or not. K⁺ cannot form stable complex with cellulose result in the KOH solution can only swell cellulose.     

Tandem white organic light-emitting diodes adopting a C60：rubrene charge generation layerTandem white organic light-emitting diodes adopting a C60：rubrene charge generation layer

Organic bulk heterojunction fullerence （C60） doped 5, 6, 11, 12-tetraphenylnaphthacene （rubrene） as the high quality charge generation layer （CGL） with high transparency and superior charge generating capability for tandem organic light emitting diodes （OLEDs） is developed. This CGL shows excellent optical transparency about 90%, which can reduce the optical interference effect formed in tandem OLEDs. There is a stable white light emission including 468 nm and 500 nm peaks from the blue emitting layer and 620 nm peak from the red emitting layer in tandem white OLEDs. A high efficiency of about 17.4 cd/A and CIE coordinates of （0.40, 0.35） at 100 cd/m2 and （0.36, 0.34） at 1000 cd/m2 have been demonstrated by employing the developed CGL, respectively.     

NUMERICAL SIMULATIONS OF HYDRODYNAMIC BEHAVIORS IN CONICAL SPOUTED BEDS

The axial and radial distributions of static pressures and vertical particle velocities of conical spouted beds have been simulated and compared with experimental data. Simulation results show that, among all factors investigated, the Actual Pressure Gradient (the APG term) in conical spouted beds, introduced as the default gravity term plus an empirical axial solid phase source term, has the most significant influence on static pressure profiles, followed by the restitution coefficient and frictional viscosity, while other factors almost have no effect. Apart from the solid bulk viscosity, almost all other factors affect the radial distribution of the axial particle velocity, although the influence of the APG term is less significant. For complex systems such as conical spouted beds where a fluidized spout region and a defluidized annulus region co-exist, the new term introduced in this work can improve the CFD simulation. Furthermore, for other systems with the Actual Pressure Gradient different from either fluidized beds or packed beds, the new approach can also be applied.     

液滴与可变形固面撞击的二维非线性激波模型

在传统的关于液固撞击的激波理论模型中，引入矢量分析的方法，考虑到高速度撞击时，液体运动的迁移性和非线性效应，以及固体的可变形性，提出了一个适用于高撞击马赫数的无量纲激波理论模型。该模型能够计算出所有撞击参数，计算结果与实验数据吻合良好。模型所导出的计算方法物理意义明确，简明准确，适用范围宽广，且便于工程上制成图表查用。     

LOCAL BIFURCATION ANALYSIS OF STRONGLY NONLINEAR DUFFING SYSTEM

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