Analytical three-dimensional renormalization for calculating effective permeabilities

The ability to calculate an effective permeability of a heterogeneous reservoir based on knowledge of its small-scale permeability is fundamental to practical numerical reservoir characterization. One elegant technique that forms the basis of this process is renormalization (King, P.R.: Transport Porous Med. 4, 37–58 (1989)). In two dimensions, renormalization can be implemented using a simple analytical formula. In three dimensions, however, no such analytical result exists, and renormalization must be performed using a numerical implementation. In this article, we present a simple analytical approximation to the method of renormalization in three dimensions. A detailed comparison with numerical results demonstrates its accuracy and highlights the significant reduction in computational cost achieved.     

Consolidation Statistics Investigation via Thin Layer Method Analysis

In this paper, the Thin Layer Method (TLM) is adapted for solving one-dimensional primary consolidation problems. It is also combined with a stochastic formulation integrating Monte Carlo simulations to investigate primary consolidation of a random heterogeneous soil profile. This latter is modeled as a set of superposed layers extending horizontally to infinity, and having random properties. Spatial variability of soil properties is considered in the vertical direction only. Soil properties of interest are elastic modulus and soil permeability, modeled herein as spatially random fields. Lognormal distribution is chosen because it is suitable for strictly non-negative random variables, and enables analyzing the large variability of such properties. The statistics regarding final settlement and its corresponding time are investigated by performing a parametric study, which integrates the influence of variation coefficient of both elastic modulus and soil permeability, and vertical correlation length. Obtained results indicate that heterogeneity significantly influences primary consolidation of the soil profile, generating a quite different way of soil grain rearrangement and water pressure dissipation in comparison to the homogeneous case, and causing a delay in the consolidation process.     

孔隙率和渗透率对LHP主芯性能影响研究

毛细多孔芯的结构参数对环路热管(LHP)主芯中的流动和传热有着重要影响.通过发展一个综合考虑了热传导、对流和蒸发多种传热效应的模型,以及利用数值模拟易于独立改变参数的特点,研究了孔隙率和渗透率这对参数组合对LHP主芯内部流场和性能的影响.模拟结果在一定范围内是合理的,且对于LHP实验研究和工程应用具有一定的参考意义.     

Structural characterization of agmatine at physiological conditions

The present work aims at determining the structure–activity relationships (SAR’s) which rule the biological function of agmatine (4-(aminobutyl)guanidinium, AGM), a biogenic amine produced by decarboxylation of arginine. Its structural preferences, both as an isolated molecule and in aqueous solution (namely at physiological conditions) were ascertained, by vibrational (Raman) spectroscopy coupled to theoretical (density functional) calculations. An evaluation of mitochondrial functions (membrane potential (ΔΨ), mitochondrial swelling, and cytochrome c release) in rat liver mitochondria (RLM) was also carried out. The results thus obtained, coupled to the conformational analysis performed for the distinct polyamine protonation states, allowed to individualize the agmatine structures which interact with the mitochondrial site responsible for its transport and for the protection against mitochondrial permeability transition (MPT) induction, as well as to gain information on the specific mechanisms involved.     

Synthesis and radical polymerization of dissymmetric fumarates with alkoxyethyl and bulky siloxy groups

Novel dissymmetric fumarate monomers ( 1a – c ) having both an alkoxyethyl group such as 2‐methoxyethyl ( a ), 2‐(2‐methoxyethoxy)ethyl ( b ), and 2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl ( c ) and a bulky 3‐[tris(trimethylsiloxy)silyl]propyl group were synthesized successfully, and their radical homopolymerizations and copolymerizations with styrene (St) were investigated. Monomer reactivities of the 1a – c in homopolymerizations were enhanced with an increase in the length of alkoxyethyl chains. The enhancement in the reactivity was explained with the suppression of the termination reaction, resulting from the increased steric hindrance induced by an increase in the size of alkoxyethyl chains. Copolymerizations of the 1a – c with St were carried out in bulk in the presence of AIBN at 60 °C, and their copolymerizations proceeded in a highly alternating tendency regardless of alkoxyethyl chain lengths. The Q, e values of the 1a – c were obtained as 0.48, +1.55 for the 1a , 0.66, +1.16 for the 1b , and 0.60, +1.16 for the 1c , respectively, from the terminal model reactivity ratios, and the 1a – c were found to be conjugative, electron‐accepting monomers. Membranes containing the 1a unit, prepared by the copolymerization of 1a with N‐vinylpyrrolidone (NVP) and terpolymerization of 1a , NVP, and 2‐hydroxyethyl methacrylate, have higher oxygen permeability than those containing no 1a unit, and also they have much better transparency compared with the membranes containing 3‐[tris(trimethylsilyloxy)silyl]propyl methacrylate unit. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 420–433, 2009     

Gas permeabilities of polyurethane films for fresh produce packaging: Response of O2 permeability to temperature and relative humidity

Thermoplastic shape memory polyurethane (SMPU) polymers were synthesized, cast to films, and their gas barrier properties were characterized. In addition, performance of an optical method was assessed by measuring oxygen permeability (P_O2) of the films. P_O2 of the SMPU film was at least two times higher than that of low density polyethylene (LDPE and increased at higher relative humidity. Permselectivity (P_CO2/P_O2) of the SMPU film was 15, which is approximately three times higher than for LDPE. The film absorbed circa 18% water vapor at 98% relative humidity. The optical method agreed very well (maximum 20% deviation) with a standard carrier gas method in P_O2 measurement. Overall our results show that SMPU is an attractive polymer for fresh produce packaging.     

Grafted polymer membranes with extractive agents for the extraction process of VO2+ ions

To conduct experiments related to the facilitated extraction phenomenon and recovery of vanadium ions VO₂⁺, two grafted polymer membranes were prepared; containing respectively cholic acid and azithromycin as extractive agents and the obtained membranes were characterized. All experiments for the facilitated extraction phenomenon of these ions were carried out. Kinetic and thermodynamic models, based on the interaction of the substrate S (VO₂⁺) with the extractive agent T, and the diffusion of the formed entity (TS) through the membrane were developed, to determine the macroscopic parameters, permeability P and initial fluxes J₀, and the microscopic parameters, association constants K_ass and apparent diffusion coefficients D*, related to the formation of entities TS and their diffusion. A clear evolution of these parameters, depending on various factors (substrate concentration C₀, extractive agent concentration and feed and receiving phases temperature), and high permeabilities for this extraction phenomenon of VO₂⁺ ions were observed for this membrane type. Copyright © 2016 John Wiley & Sons, Ltd.     

Polylactic acid-based polyurethane/polyamide 6,12 and graphene nanocomposite: Structure and physical property study for packaging application

This effort reports on novel polylactic acid-derived polyurethane (PU) and polyamide 6,12 (PA6,12)-based blends and graphene-reinforced nanocomposite. PU/PA6,12 (50:50) blend was opted as matrix based on molecular weight and shear stress performance. PU/PA6,12 with 5?wt% graphene (PU/PA6,12/graphene 3) showed improved T₀ and T_max of 515 and 541°C relative to neat blend. PU/PA6,12/graphene 3 also revealed significantly high tensile (53?MPa) and flexural strength (1,711?MPa). For Eschericia coli, Staphylococcus, and Pseudomonas bacterial strains, nanocomposite with higher graphene loading produced significant inhibitory effects. Novel nanocomposites displayed fine antimicrobial and barrier properties against O₂ and H₂O to be used as a packaging material.     

磺化聚苯醚酮质子交换膜的制备与表征

设计、合成了一种含氰基双氯单体,其结构特点是氰基分布在3个以间位醚键相连的苯环上。以此单体和2,5-二氯-3'-磺酸钠二苯甲酮为原料,利用Ni(0)催化偶联反应制备了微嵌段型质子交换膜材料(中等长度磺化聚苯-三氰基聚苯醚酮共聚物(m-SPP-co-PAEK 3CN x),x代表聚合物的离子交换容量)。结果表明,与相同离子交换容量的磺化聚合物相比,该类聚合物膜表现出较低的吸水、溶胀率和较低的甲醇渗透性能。以离子交换容量2.16为例,80℃下,m-SPP-co-PAEK 3CN 2.16的吸水率、溶胀率分别为29.7%、28.2%,而SPP-co-PAEK MO 2.33的吸水率、溶胀率分别为80.2%、37.2%。25℃下,二者的甲醇渗透系数分别为2.38和7.20。聚合物骨架结构中存在丰富的氰基基团,导致膜具有良好的尺寸稳定性和较低的甲醇渗透性能。基于这些优异的性能,新制备的膜材料在燃料电池领域显示了潜在的应用前景。     

中变质煤小分子相对煤的吸附及渗流特性影响

为研究煤中小分子对煤的瓦斯吸附及流动特性的影响,采用四氢呋喃溶剂萃取煤中可溶有机小分子,得到萃取后煤样(残煤)。对原煤和残煤分别进行甲烷等温吸附、解吸实验和径向渗流实验;同时,采用氮气吸附法测试了它们的孔隙结构参数。结果表明,残煤的饱和吸附量a值低于原煤,吸附常数b值增大,萃取小分子降低了煤对甲烷的吸附能力,提高了低压段(<4 MPa)煤对甲烷的解吸速率;原煤的孔体积和平均孔径高于残煤,比表面积和微孔孔体积却减少;萃取后,煤粒表面传质阻力和扩散阻力均减小,残煤甲烷解吸速率和解吸量均高于原煤;同一渗流条件下,残煤的渗透率明显高于原煤。分析认为,煤中部分小分子被溶解后,煤孔隙结构的改变,降低了煤对瓦斯的吸附能力,减小了甲烷在煤粒中的内外扩散阻力,扩大了瓦斯在煤中的流动通道,改变了煤层储运特性,为煤储层的化学增透提供依据。