基于漂浮有机液滴凝固液相微萃取的黄酮类化合物分配系数及含量测定

以漂浮有机液滴凝固液相微萃取（SFODLPME）对中药中黄酮类化合物进行富集,建立SFODLPME-HPLC快速测定中药材样品中低丰度黄酮类化学成分含量的方法. 并讨论了黄酮类化合物富集倍数与浓度之间的关系、富集倍数与供相体积之间的关系,定义和阐述了EF1μg?mL-1及其物理意义,计算了漂浮有机液滴凝固相体积及黄酮类化合物的表观分配系数. 在SFODLPME的优化条件下结合高效液相色谱测得8种黄酮类成分的线性范围均为0.01~10.00μg/ml;检测限在1.0~0.01ng/mL;精密度RSD<7.0%;药材中分析物的回收率在96.0% ~104.2%. 当加入萃取溶剂体积为40μl 时,形成漂浮有机液滴凝固相体积为52±14μl;8种黄酮类成分的表观分配系数在44.8~243.9之间.     

A thermodynamically consistent numerical method for a phase field model of solidification

A discretization is presented for the initial boundary value problem of solidification as described in the phase-field model developed by Penrose and Fife (1990) [1] and Wang et al. (1993) [2]. These are models that are completely derived from the laws of thermodynamics, and the algorithms that we propose are formulated to strictly preserve them. Hence, the discrete solutions obtained can be understood as discrete dynamical systems satisfying discrete versions of the first and second laws of thermodynamics. The proposed methods are based on a finite element discretization in space and a midpoint-type finite-difference discretization in time. By using so-called discrete gradient operators, the conservation/entropic character of the continuum model is inherited in the numerical solution, as well as its Lyapunov stability in pure solid/liquid equilibria.     

Eutectic structures in the Ni–Co–Cr–Al system obtained by plasma spraying and by Bridgman growth

Formation of a regular fibrous two-phase microstructure was found in low-pressure plasma spray (LPPS) deposited Ni–Co–Cr–Al–Y coatings by transmission electron microscopy and analyzed by energy dispersive spectroscopy. The structure is compared to aligned lamellar three-phase structures of an Ni–Co–Cr–Al alloy obtained on Bridgman growth under slow unidirectional solidification (UDS) conditions. The composition of the Ni–Co–Cr–Al alloy for UDS experiments has been identified by DTA. The conditions for the formation of both the LPPS and the UDS structures are discussed.     

液态金属Al凝固过程中的团簇结构与幻数特性

采用分子动力学方法,对含有100000个Al原子的液态金属系统在凝固过程中团簇结构的形成特性进行了模拟研究,并采用原子团类型指数法(CTIM)来描述各种类型的团簇结构组态.研究结果显示:在液态金属Al的凝固过程中,只有与1551键型相关的二十面体原子团(12 0 12 0)及其组合形成的各种团簇结构,对微结构的演变起着关键的、决定性的作用;由不同数目、不同类型基本原子团组成的各种层次的团簇结构,都在一定的原子数区段内呈现出峰值,即幻数点;系统的幻数序列为:13(13), 19(21), 25～28(27), 31～33(29～30) ,37、39,…(括号内为液态时对应的幻数值),与Harris等人的实验结果甚为相符.本模拟研究所用的团簇结构按层次区段来研究幻数序列的方法,可为实验结果提供更为合理的模型解释.     

Preconcentration of valsartan by dispersive liquid–liquid microextraction based on solidification of floating organic drop and its determination in urine sample: Central composite design

In this work, a fast, easy, and efficient dispersive liquid–liquid microextraction method based on solidification of floating organic drop followed by high‐performance liquid chromatography with UV detection was developed for the separation/preconcentration and determination of the drug valsartan. Experimental design was applied for the optimization of the effective variables (such as volume of extracting and dispersing solvents, ionic strength, and pH) on the extraction efficiency of valsartan from urine samples. The optimized values were 250.0 μL ethanol, 65.0 μL 1‐dodecanol, 4.0% w/v NaCl, pH 3.8, 1.0 min extraction time, and 4.0 min centrifugation at 4000 rpm min^?1. The linear response (r² = 0.997) was obtained in the range of 0.013–10.0 μg mL^?1 with a limit of detection of 4.0 ng mL^?1 and relative standard deviations of less than 5.0 % (n = 6).     

Efficiencies of Various in situ Polymerizations of Liquid Electrolytes and the Practical Implications for Quasi Solid-state Batteries

In situ polymerization of liquid electrolytes is currently the most feasible way for constructing solid-state batteries, which, however, is affected by various interfering factors of reactions and so the electrochemical performance of cells. To disclose the effects from polymerization conditions, two types of generally used in situ polymerizing reactions of ring-opening polymerization (ROP) and double bond radical polymerization (DBRP) were investigated on the aspects of monomer conversion and electrochemical properties (Li⁺-conductivity and interfacial stability). The ROP generated poly-ester and poly-carbonate show a high monomer conversion of ≈90 %, but suffer a poor Li⁺-conductivity of lower than 2×10⁻⁵ S cm⁻¹ at room temperature (RT). Additionally, the terminal alkoxy anion derived from the ROP is not resistant to high-voltage cathodes. While, the DBRP produced poly-VEC(vinyl ethylene carbonate) and poly-VC(vinylene carbonate) show lower monomer conversions of 50–80 %, delivering relatively higher Li⁺-conductivities of 2×10⁻⁴ S cm⁻¹ at RT. Compared two polymerizing reactions and four monomers, the VEC-based F-containing copolymer possesses advantages in Li⁺-conductivity and antioxidant capacity, which also shows simultaneous stability towards Li-metal with the help of LiF-based passivating layer, allowing a long-term stable cycling of high-voltage quasi solid-state cells.     

Levitation of metallic melt by using the simultaneous imposition of the alternating and the static magnetic fields

This study developed a new levitation method, which used the simultaneous imposition of static and alternating magnetic fields. Dynamic behavior was measured for pure Cu and pure Ni melts levitated by the proposed method. The oscillation due to surface tension and convection in levitated Cu melts were hardly observed at static magnetic fields exceeding 1 T. Only the rotation of this axis parallel to the static magnetic field was observed under high static magnetic fields. The proposed method demonstrated that metallic melt could be statically levitated like a solid sphere. It was also found that stable levitation of paramagnetic Ni melt was rather difficult at static magnetic fields exceeding 5 T, because of the magnetization force.     

Growths of bubble/pore sizes in solid during solidification—an in situ measurement and analysis

The sizes of a bubble trapped in solid after nucleation on the solidification front during an upward freezing of water containing a dissolved oxygen or carbon dioxide gas are experimentally measured and quantitatively predicted in this work. The sizes of the bubble include the height, radius and contact angle of the cap on the solidification front and the length of the bubble in the solid. From in situ measurements of bubble shapes in solid at cold temperatures of −25° and −15°C, it quantitatively shows that pore formation can be divided into five regimes: (1) nucleation on the solidification front, (2) spherical growth, (3) solidification rate-controlled elongation, (4) disappearance of the bubbles, and (5) formation of the pores in solid. To interpret experimental results, equations incorporated with the growth rate of a spherical bubble and solidification rate to predict bubble shapes in the solid during the spherical growth and solidification rate-controlled elongation are successfully proposed. It is found that the time to reach the regime of solidification rate-controlled elongation corresponding to the maximum radius of the bubble is increased by decreasing solidification rate and increasing spherical growth rate of the bubble. Experimental data show the effects of initial gas concentration and solidification rate on geometries of the bubble in solid. Valuable database for more systematical studies of pore formation in solids are provided.     

用差热分析(DTA)法对环氧树脂固化条件的研究

用热分析方法研究了环氧树脂与乙二胺,二乙胺三胺,三乙醇胺,六次甲基四胺,邻苯二甲酸酐及顺丁烯二酸酐的固化条件。     

Solidification behavior of falling germanium droplets produced by pulsated orifice ejection method

In order to clarify containerless solidification mechanism of falling semiconductor microdroplets, the monosized droplets of germanium in the size range from 200 to 500 μm were ejected by pulsated orifice ejection apparatus method. The density of grains in the resultant particles was dramatically reduced by decreasing the ejection temperature, i.e. initial temperature. A surface observation and orientation imaging microscopy analysis proposed that such microstructural transition was derived from the dependency of preferred growth direction on the undercooling level: the initial temperature determined the solidification undercooling. Numerical calculation with the classical nucleation theory was performed to discuss this phenomenon, but could not sufficiently elucidate the effect of initial temperature obtained experimentally.