基于三维网络模型的水驱油微观渗流机理研究

利用逾渗网络模型在微观水平进行随机模拟来研究水驱油的微观渗流规律,通过模型计 算结果与油水稳态相对渗透率驱替实验结果对比验证了网络模拟的有效性. 在此基础上,讨 论了在不同润湿条件下、水驱不同阶段的剩余油微观分布规律. 将剩余油分布形态归纳为4 种状态：孤粒/孤滴状、斑块状、网络状和油水混合状态. 研究表明,网络状剩余油的块数 较少,但所占体积比例较大. 随着剩余油饱和度的降低,最大网络状油所占孔隙数减少,剩 余油饱和度在40{\%}$\sim$50{\%}附近开始以较快速度减少. 润湿性不仅影响驱油效率,也影响剩余油分布形态. 在驱替过程中,剩余油分布总的变化趋势是逐渐趋于分散.     

Catalytic cyclometalation reaction of unsaturated compounds in synthesis of magnesa- and aluminacarbocycles

The investigation results on design and application of the new catalytic cyclometalation reaction of olefins, dienes, acetylenes and allenes with Al, Mg and halogen alkyls mediated by Ti or Zr based metallocene catalysts to produce novel classes of cyclic organometallics namely aluminacyclopropanes, aluminacyclopropenes, aluminacyclopentanes, aluminacyclopentenes, aluminacyclopenta-2,4-dienes, magnesacyclopentanes, magnesacyclopentenes, magnesacyclopenta-2,4-dienes as well as metallamacrocycles are summarized and systematized. Selected literature data on thermal synthesis of cyclic organoaluminum and organomagnesium compounds for comparison the efficiencies of catalytic and classic synthetic methods are given. Mechanistic aspects of catalytic cyclometalation of unsaturated compounds and chemical transformations of Al and Mg metallacycles are discussed.     

Numerical analysis of a finite volume scheme for a seawater intrusion model with cross‐diffusion in an unconfined aquifer

We consider a degenerate parabolic system modeling the flow of fresh and saltwater in a porous medium in the context of seawater intrusion. We propose and analyze a finite volume scheme based on two‐point flux approximation with upwind mobilities. The scheme preserves at the discrete level the main features of the continuous problem, namely the nonnegativity of the solutions, the decay of the energy and the control of the entropy and its dissipation. Based on these nonlinear stability results, we show that the scheme converges toward a weak solution to the problem. Numerical results are provided to illustrate the behavior of the model and of the scheme.     

二维非饱和水流的全离散广义差分格式分析及其数值模拟

建立二维非饱和水流问题的全离散广义差分格式,讨论了全离散广义差分解的存在唯一性,并给出最优误差估计的证明．最后给出数值算例,验证方法的有效性.     

Effect of clay silylation on curing and mechanical and thermal properties of unsaturated polyester/montmorillonite nanocomposites

This work focuses on the chemical modification of montmorillonite (MMT) (Cloisite® Na) with compatible silanes, vinyltriethoxysilane (CVTES) and γ-methacryloxypropyltrimethoxysilane (CMPS) in order to prevent agglomeration and to improve montmorillonite interaction with an unsaturated polyester resin matrix seeking to achieve a multifunctional composite. Clays were dispersed in the resin by mechanical stirring and sonication and the nanocomposites were prepared by resin transfer into a mold. The mechanical, morphological, thermal and flammability properties of the obtained composites were compared with those prepared using commercial Cloisite® 30B (C30B) and Cloisite® 15A (C15A) clays. Advantages of using silane-modified clays (CVTES and CMPS) as compared with organic-modified clays (C30B and C15A) can be summarized as similar flexural strength and linear burning rate but higher storage modulus and improved adhesion to the polyester resin with consequent higher thermal deflection temperature and reinforcement effectiveness at higher temperatures. However, organic modified clays showed better dispersion (tendency to exfoliate) and consequently delayed thermal volatilization due to the clay barrier effect.     

Morphology and non-isothermal crystallization of dynamically vulcanized PP/EPDM blends in situ compatibilized via magnesium dimethacrylate

Polypropylene/ethylene-propylene-diene rubber (PP/EPDM) blends in situ compatibilized by magnesium dimethacrylate (MDMA) were fabricated via peroxide-induced dynamic vulcanization. Scanning electron microscope observation indicated that the size of cross-linked EPDM particles decreased with incorporation of MDMA. Polarizing Optical Microscope (POM) analysis suggested that the spherulite size of PP phase decreased sharply with incorporation of MDMA during dynamic vulcanization. The Pseudo-Avrami, Ozawa and Mo's models were applied to analyze the non-isothermal crystallization kinetics of the composites. The analyzed data indicated that the crosslinked EPDM particles and homopolymerized MDMA acted as heterogeneous nucleating agents, which enhanced the crystallizability and decreased the spherulite size of the PP phase. In addition, the non-isothermal crystallization activation energy (ΔE) was calculated through the Kissinger and Friedman methods, and the ΔE value was found increase with incorporation of MDMA.     

The Reaction of 1-Aryl-2-(4-nitrophenylsulfonyl)ethanones with α,β-Unsaturated Esters

1-Aryl-2-(4-nitrophenylsulfonyl)ethanones (1) reacted with one equiv. of α,β-unsaturated esters at 60°C to afford the tandem addition-rearrangement products (3), while at 75°C 1a reacted with two equiv. of methyl acrylate and gave an unexpected addition-rearrangement-addition-annulation product which is dimethyl 4-hydroxyl-1-(4-nitrophenyl)-4-phenyl-1,3-cyclohexyldicarboxylate (4). A mechanism is suggested.     

NOVEL 2-THIOXOHYDANTOIN KETENE DITHIOACETALS: VERSATILE INTERMEDIATES FOR SYNTHESIS OF METHYLSULFANYLIMIDAZO- [4,5-C]PYRAZOLES AND METHYLSULFANYLPYRROLO- [1,2-C]IMIDAZOLES

ABSTRACT

The novel 2-thioxohydantoin ketene S,S-acetals 3a,b were prepared by the reaction of 2-thioxohydantoins 1a,b with carbon disulfide, followed by alkylation with methyl iodide of the produced sodium dithiolate salts 2a,b. The reaction of compounds 3a,b with nucleophiles afforded different fused methylsulfanylimidazoles.     

A robust Ru-PNNP catalyst system for the asymmetric hydrogenation of α,β-unsaturated ketones to allylic alcohol

A robust and stable Ru-Biphosphinobioxazoline catalyst system is discovered for the highly enantioselective hydrogenation of enones to allylic alcohols. A series of acyclic α,β-unsaturated ketones react well affording the desired products in high yields (up to 98%) and enantioselectivities (up to 98% ee). Simple manipulation process and tolerance of water and air make this catalysis more practical and appealing.     

Antimicrobial activity of new bicyclic lactones with three or four methyl groups obtained both synthetically and biosynthetically

Ten new derivatives of isophorone were obtained through a five-step synthesis. Among the products were several unsaturated, bicyclic lactones with three or four methyl groups. These lactones were used as the substrates for biotransformation mediated by selected fungal strains (Fusarium species, Syncephalastrum racemosum, Cunninghamella japonica, Penicillium species, Absidia species, and Pleurotus ostreatus). Four new hydroxylactones were obtained as a result of biotransformation. Because the unsaturated lactone with four methyl groups was a diastereoisomeric mixture, a structural analysis was conducted. The hydroxylactones were also included in this analysis. Both the unsaturated lactones and hydroxylactones were examined for their antimicrobial activity. It was found that some of these compounds exhibited growth inhibition against pathogenic strains of bacteria (Staphylococcus aureus, Pseudomonas fluorescens), yeasts (Candida albicans) and filamentous fungi (Alternaria sp., Penicillium sp.). All obtained compounds were also subjected to scent analysis.