Transient electrophoresis of a charged porous particle

The starting electrophoretic motion of a porous, uniformly charged, spherical particle, which models a solvent-permeable and ion-penetrable polyelectrolyte coil or floc of nanoparticles, in an arbitrary electrolyte solution due to the sudden application of an electric field is studied for the first time. The unsteady Stokes/Brinkman equations with the electric force term governing the fluid velocity fields are solved by means of the Laplace transform. An analytical formula for the electrophoretic mobility of the porous sphere is obtained as a function of the dimensionless parameters , , , and , where a is the radius of the particle, κ is the Debye screening parameter, λ is the reciprocal of the square root of the fluid permeability in the particle, ρ_p and ρ are the mass densities of the particle and fluid, respectively, ν is the kinematic viscosity of the fluid, and t is the time. The electrophoretic mobility normalized by its steady-state value increases monotonically with increases in and , but decreases monotonically with an increase in , keeping the other parameters unchanged. In general, a porous particle with a high fluid permeability trails behind an identical porous particle with a lower permeability and a corresponding hard particle in the growth of the normalized electrophoretic mobility The normalized electrophoretic acceleration of the porous sphere decreases monotonically with an increase in the time and increases with an increase in from zero at .     

Cr-β沸石的合成与催化性能研究

在SiO₂-Cr₂O₃-(TEA)₂O-Na₂O-H₂O体系中，以四乙基氢氧化铵(TEAOH)为模板剂合成了Cr-β沸石，用XRD、IR、SEM及DTA-TGA等方法对样品进行了表征，探讨了反应混合物组成对Cr-β沸石晶化的影响，初步考查了Cr-β沸石催化苯酚与过氧化氢的羟基化反应活性。     

Sequential C–O decarboxylative vinylation/C–H arylation of cyclic oxalates via a nickel-catalyzed multicomponent radical cascade

A selective, sequential C–O decarboxylative vinylation/C–H arylation of cyclic alcohol derivatives enabled by visible-light photoredox/nickel dual catalysis is described. This protocol utilizes a multicomponent radical cascade process, i.e. decarboxylative vinylation/1,5-HAT/aryl cross-coupling, to achieve efficient, site-selective dual-functionalization of saturated cyclic hydrocarbons in one single operation. This synergistic protocol provides straightforward access to sp³-enriched scaffolds and an alternative retrosynthetic disconnection to diversely functionalized saturated ring systems from the simple starting materials.

A selective, sequential C–O decarboxylative vinylation/C–H arylation of cyclic alcohol derivatives enabled by visible-light photoredox/nickel dual catalysis has been described.     

用引发转移终止剂制备嵌段和接枝共聚物

介绍了引发转移终止剂(Iniferter)的概念及其引发“活性”自由基聚合的原理。综述了Iniferter在制备ABA型三嵌段共聚物和接枝共聚物中的应用和发展。     

有机锆交联剂的制备及其性能

随着油田深部调剖应用的不断推广，以及环保要求的提高，适用于深部调剖调驱体系的低污染有机锆交联剂逐渐受到关注。以ZrOCl₂·8H₂O、乳酸、乙二胺、硫脲为原料，制备了有机锆交联剂和HPAM-锆交联凝胶，其结构和性能经SEM和岩心驱替装置表征。并利用正交实验法优化了制备条件。结果表明：制备有机锆交联剂的最佳条件为：氧氯化锆、乳酸、乙二胺及硫脲的质量比为7.8/1/6.7/5，反应温度为70 ℃，反应时间为3 h。交联温度为60 ℃，HPAM浓度为2 g·L^-1、聚锆比为30/1时，聚合物凝胶成胶强度达到24968 mPa·s，成胶时间约8 h，凝胶体系可维持90 d不破胶。在级差为3.9的双管驱替岩心实验中，两管的岩心分流率均接近50%，剖面改善率达到66.77%。     

一种超支化阳离子聚合物的制备及其防膨性能

以顺丁烯二酸酐及二乙醇胺为原料，采用“一步熔融法”合成了端羟基超支化聚酯酰胺（HBP-OH）；以环氧氯丙烷改性HBP-OH制得端基为氯甲基的超支化聚酯酰胺（HBP-ECH）；以三乙胺改性HBP-ECH制得端基为季铵基的超支化聚酯酰胺（HBP-L），其结构经IR表征。研究了HBP-L的静态防膨率、耐水洗能力及对岩心的渗透伤害率。结果表明：HBP-L加量为1 wt%时，粘土防膨率为90.36%；经10次水洗后，其防膨率仍超过85%；模拟地层温度为45 ℃时，HBP-L对岩心的渗透伤害率仅3.86%。采用XRD和Zeta电位法分析了HBP-L对粘土水化膨胀及运移分散的抑制机理。结果表明：经1 wt%HBP-L处理的粘土，其晶层间距为6.91 nm，较去离子水处理层间距（4.71 nm）小；粘土表面的zeta电位由-39.2 mV升高至-19.6 mV。     

Sweet pregnane glycosides from Telosma procumbens

An intensely sweet polyoxypregnane glycoside, telosmoside A15 (15), was isolated from an Asian Asclepiadaceae plant, Telosma procumbens, collected in Vietnam. This is the first time a sweet pregnane glycoside has been found, and its sweetness intensity is 1000 times greater than that of sucrose. From the same plant, 17 other new glycosides were isolated, having the same aglycone; they are named telosmosides A1-A14 (1-14) and A16-A18 (16-18). Some of these glycosides are also sweet, but others are tasteless or bitter. Chemical structures of the 18 glycosides were determined, and the structure-taste relationship was discussed.     

Ion-ion reactions for charge reduction of biopolymer at atmospheric pressure ambient

Extractive electrospray ionization source(EESI)was adapted for ion-ion reaction,which was demonstrated by using a linear quadrupole ion trap mass spectrometer for the first ion-ion reaction of biopolymers in the atmospheric pressure ambient.     

钴希夫碱配合物的合成及其氧合机制的研究——Ⅰ.配合物及其氧加合物的合成和表征

本文合成了一系列以水杨醛或萘酚醛同多胺缩合的四齿(N₂O₂)或五齿(N₃O₂)希夫碱为配体的钴希夫碱配合物及它们的氧加合物,用元素分析、红外光谱、磁化率以及ESR谱进行了表征,在续篇中将继续讨论配合物的吸氧行为和氧合机制。     

Reversible wettability of a chemical vapor deposition prepared ZnO film between superhydrophobicity and superhydrophilicity

A superhydrophobic ZnO thin film was fabricated by the Au-catalyzed chemical vapor deposition method. The surface of the film exhibits hierarchical structure with nanostructures on sub-microstructures. The water contact angle (CA) was 164.3 degrees, turning into a superhydrophilic one (CA < 5 degrees) after UV illumination, which can be recovered through being placed in the dark or being heated. The film was attached tightly to the substrate, showing good stability and durability. The surface structures were characterized by scanning electron microscopy and atomic force microscopy.