Membrane Permeability and Stability of Liposomes Suspended in Shear Flow

The 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposome has been characterized in its stability and membrane permeability to 5(6)-carboxyfluorescein (CF) in the shear flow generated in the cone-and-plate geometry. The CF-containing liposomes (CFLs) were 101–323 nm in the mean diameter D _P as measured with the dynamic light scattering (DLS) method. Adsorption of lipids to the cone-and-plate was observed, which clearly depended on the shear stress applied at the shear rate γ up to 1.5 × 10³ s^?1. The permeability of CFLs with D _P of 101 and 117 nm definitely increased at the maximum γ value where the adsorption was negligible. The permeability coefficient of CF at 40°C in the shear flow was 5.7 times larger than that in the static liquid system. The DLS measurements revealed that the size distribution of CFLs with D _P of 101–189 nm was practically unchanged under the shear stress even at 55°C. The results obtained show that the shear stress can permeabilize the CFL membranes with neither structural collapse nor coalescence.     

直流电场对水驱油藏油水相对渗透率的影响研究

研究、分析了直流电场强度、方向等因素对油藏岩石油水相对渗透率的影响及其作用机理.实验表明,在直流电场作用下,岩心呈强水湿性,束缚水饱和度增大,残余油饱和度降低;随着电场强度的增加,油相相对渗透率增大,水相相对渗透率降低;其极性相和非极性相各自呈现的不同渗流特性、壁面双电层结构变化以及原油的电粘效应等都是影响油水相对渗透率的因素.     

Fluorescent Nitrogen-Doped Carbon Dots for Label Live Elder Blood-Stage Plasmodium falciparum through New Permeability Pathways

To verify the size and emergence time of new permeability pathways (NPPs) in malaria parasites, the permeability of the Plasmodium falciparum-infected erythrocytes was tested with different particle sizes of nanomaterials by flow cytometry assay. The results confirmed the permeability of the host cell membrane increases with parasite maturation for the stage-development evolution of NPPs, and especially found that a particle size of about 50 nm had higher efficiency. As a kind of the novel nanomaterials, nitrogen-doped carbon dots (NCDs) showed no toxicity, specificity binding ability to the malaria parasites, and could label live elder blood-stage P. falciparum through NPPs, indicating the potential application in cell imaging. NPPs and some nanomaterials such as NCDs deserve more attention and exploration for the elimination and prevention of malaria.     

Permeability relationships of polyimide copolymers

The permeability of the homopolymers 6FDA-3BDAF and 6FDA-4BDAF and of the copolymers 6FDA-4/2BDAF, 6FDA-4/3BDAF, and 6FDA-4/3/2BDAF to He, CO₂, and CH₄ was measured at 35.0°C and at pressures up to 10 atm. The experimental values of the permeability coefficients for the copolymers are in satisfactory agreement with the values estimated from the permeability coefficients for the constituent homopolymers and their weight fractions. The synthesis of the fluorine-containing diamine 2BDAF is reported for the first time. © 1994 John Wiley & Sons, Inc.     

含聚二甲基硅氧烷短支链的聚酰亚胺的合成及其透氧性的研究

介绍了在甲撑二苯胺的亚甲基上接上聚二甲基硅氧烷短链，并用含二甲基硅氧烷短链的二苯胺单体和均苯四甲酸二酐反应制取聚酰亚胺的方法。实验结果表明，在含三硅量相同的情况下，支链型的改性聚酰亚胺的机械强度高。氧的透过系数随支链长度的增加而增加，当二甲基硅氧烷短链的硅原子由１增加到４时，透氧系数由３．６５Ｂａｒｒｅ增加到１２．０Ｂａｒｒｅ，而Ｏ２／Ｎ２分离系数则由６．４降到３．５。     

聚酯聚氨酯透气性的正电子研究

用正电子湮没寿命谱(PALS)研究了温度和PEG含量对以聚己二酸丁二醇酯(PBA)为软段的聚酯聚氨酯的自由体积特性和透气性的影响.实验结果表明,自由体积空洞的体积随着温度的升高而增加,分布变宽,导致透气性增大.不同PEG含量的聚酯聚氨酯PBA-10,PBA-15和PBA-20的水汽渗透系数(WVP)基本相同.结果表明,在这类聚氨酯中,影响透气性的主要因素不仅是自由体积,而且与材料的亲水性有关.     

A Bunch‐Like Tertiary Amine Grafted Polysulfone Membrane for VRFBs with Simultaneously High Proton Conductivity and Low Vanadium Ion Permeability

Novel polysulfone membranes with bunch‐like tertiary amine groups are synthesized with high ion selectivity and outstanding chemical stability for vanadium redox flow batteries (VRFBs). The bunch‐like tertiary amine groups simultaneously act as an ionic conductor for proton hopping and vanadium ion transport obstacles. The performance of the membrane is tuned via controlling the grafting degree of the chloromethylated polysulfone. The results show that membranes show increasing proton over vanadium ion (σ/p ) selectivity with increasing functional tertiary groups. VRFBs assembled with the prepared membranes demonstrate an impressive Coulombic efficiency of 98.9% and energy efficiency of 90.9% at a current density of 50 mA cm⁻². Furthermore, the prepared membrane reported in this work shows excellent stability in 1 m VO₂ ⁺ solution at 35 °C over 240 h. Overall, the synthesized polymers provide a new insight into the design of high‐performance membranes toward VRFB applications.

     

分子结构对聚芳醚酮薄膜透气性的影响

分子结构对聚芳醚酮薄膜透气性的影响王忠刚，陈天禄，徐纪平（中国科学院长春应用化学研究所长春１３００２２）关键词聚芳醚酮，气体分离膜，结构－性能关系为了改善聚合物薄膜的透气性能，开发具有高透气性和高选择性的膜材料，人们对膜分子结构与透气性能间的关系进行...     

无电渗流的毛细管电泳

无电渗流毛细管电泳是毛细管电泳的一种新技术。本文对基产生条件及其在毛细管区带电泳与胶束电动毛细管色谱中的分离特点进行了详细介绍。     

Study on the Gas Permeability of Nickel(II) Polyurethane Complexes

Ionic polyurethanes (PUs) were prepared from hydroxyl‐terminated polybutadiene (HTPB) and 4,4′‐dicyclohexylmethane diisocyanate (H₁₂MDI) by a two‐stage method. The ionic group was introduced by adding 4,8‐diazaundecanediamide (L‐2,3,2) as the chain extender of which the tertiary amines and carbonyl groups were complexed with nickel ions. It was found that the binding of hard segments and the flexibility of soft segments had subtle effects on the gas permeability. The effects of hard segment content and the amount of nickel ion on the gas permeability and morphological properties were investigated. Fourier transform infrared (FTIR) spectroscopy was utilized to identify the segregation between hard and soft segments and structure change, which affect the transport properties. The hydrogen bonding index (HBI), frequency difference, and shift as a measure of the phase segregation and the average strength of the interpolymer hydrogen bonds were utilized to study the intermolecular interaction and transport property of the prepared PUs. The oxygen and nitrogen permeabilities of membranes were determined by using gas permeability analyzer. The results of FTIR, differential scanning calorimetry and thermogravimetric analysis measurements explain the complexation and, hence, the gas permeability.     

Gas transport in polybutadiene treated with aqueous bromine

Diffusion, solubility, and permebility coefficients were measured for He, Co₂, Ar, and CH₄ in polybutadiene (PB) and in polybutadiene reacted in the solid state to various extents with aqueous bromine. Analysis of the sorption curves and X-ray emission spectra showed that the bromination created a heterogeneous membrane with an outer brominated skin and an unreacted core. At relatively low extent of bromination, the diffusion and permeability coefficients for CO₂, Ar, and CH₄ decreased by two orders of magnitude, while the transport coefficients for He were virtually unchanged. The permeability coefficients for CO₂, Ar, and CH₄ became immeasurably small after about 3% bromination. The ideal separation factor for gas pairs with different molecular size increased with bromination, suggesting applications in gas separation processes. © 1993 John Wiley & Sons, Inc.     

Flow through Porous Media XVI: Electrokinetic Transport Coefficients of Aqueous Solutions of Mercuric Chloride and Glycine through a Sintered Disc Impregnated with a Cellulose Acetate Membrane under a Magnetic Field

The effect of the magnetic field on the electrokinetic transport coefficients (permeability coefficient and electro-osmotic permeability coefficient) of water and aqueous solutions of mercuric chloride and glycine through a sintered disc impregnated with cellulose acetate at different potentials, concentrations, and magnetic fields varying up to 21 kg/cm² are reported at 308.15 K. The phenomenological coefficients characterizing the electro-osmotic flow and the membrane characteristics are also estimated for the various solutions with the object of determining the efficiencies of electrokinetic energy conversion and ζ potential. The effect of magnetic field has been attributed to the molecular orientation of dipoles in solutions and to the change in the structure of the membrane.     

Permeability of polymer/clay nanocomposites: A review

This is a review of the existing studies on the permeability of gas molecules in nanocomposite materials that consist of inorganic platelet-shaped fillers in polymeric matrices. We describe the dominant mechanisms for the transport of small molecules in polymers and polymer nanocomposites, as well as the procedures for the measurement of the permeability and the diffusivity. The emphasis is given on the various models that have been proposed for the prediction of permeability in polymer-clay nanocomposites. The influence of the characteristics of the inorganic particles on the barrier properties of the composite membrane is discussed and tested using the model and the available experimental data. Some aspects on the methods of improving the barrier properties of the nanocomposite are examined and a few applications of these materials as gas barriers are presented.     

Synthesis and Gas Permeability of Cyclotetrasiloxane-Containing Methacrylate Copolymers

Abstract

Synthesis and gas permeability of random and block copolymers of a cyclotetrasiloxane-containing methacrylate have been studied in comparison with those of tris(trimethylsiloxy)silane-containing methacrylate (MTTS) copolymers. Random and block copolymers of 3-(heptamethyl cyclotetrasiloxanyl) propyl methacrylate (HCPM) and methyl methacrylate (MMA) were prepared by radical copolymerization using 2,2′-azobisisobutyronitrile and a poly(azoinitiator), poly(1,6-hexamethylene 4,4′-azobiscyanopentanoate), respectively. Differential scanning calorimetry (DSC) revealed that HCPM-MMA block copolymers exhibited heterogeneous phases, as evidenced by two distinct glass transition temperatures due to poly-HCPM (PHCPM) block and PMMA block, while the single glass transition temperatures in the homogeneous phases in HCPM-MMA random copolymers lowered with HCPM content. The oxygen and nitrogen gas permeability coefficients of HCPM-MMA random copolymer films measured at 23°C were found to steeply increase with HCPM contents, although those of HCPM-MMA block copolymers slightly increased. The permeability coefficients of MTTS-MMA random copolymers prevailed over those of HCPM-MMA random copolymers despite the same four Si atoms, probably because of its free volume effect. Further, the HCPM content dependency on the diffusion and solubility coefficients, and the effect of crosslinking on their gas permeability were also discussed.     

改善细胞通透性促进1,3-丙二醇生物合成

克雷伯杆菌发酵生产1,3-丙二醇(1,3-PD)的过程中, 通过加入表面活性剂可改善细胞通透性, 以减少产物和副产物对细胞生长与代谢的抑制作用, 从而促进细菌生长和1,3-PD产出. 对比研究了吐温-80 (Tween-80)、曲拉通X-100 (Triton X-100)、壬基酚聚氧乙烯醚-10 (OP-10)和十六烷基三甲基溴化铵(CTAB)等对发酵中甘油脱氢酶(GDH)、1,3-丙二醇氧化还原酶(PDOR)和甘油脱水酶(GDHt)等3种关键酶活的影响. 实验表明OP-10能较好改善细胞通透性, 胞内释放核酸浓度随添加OP-10量的增加有明显提高. 低浓度的OP-10对GDH, PDOR活性及细胞生长有较好的促进作用; 发酵8～12 h时添加1.0 g•L－1的OP-10可使1,3-PD浓度和摩尔转化率有较大提高. 结合透射电镜发现非离子表面活性剂OP-10损伤膜结构, 致细胞通透性改变, 有利于充分发挥细胞内酶的催化活性, 对细菌生长和1,3-丙二醇的合成有较大促进作用.     

Extracts Prepared from Feed Supplements Containing Wood Lignans Improve Intestinal Health by Strengthening Barrier Integrity and Reducing Inflammation

Lignans are known to exhibit a broad spectrum of biological activities, indicating their potential as constituents of feed supplements. This study investigated two extracts derived from the feed supplements ‘ROI’ and ‘Protect’—which contain the wood lignans magnolol and honokiol (‘ROI’), or soluble tannins additional to the aforementioned lignans (‘Protect’)—and their impact on selected parameters of intestinal functionality. The antioxidant and anti-inflammatory properties of the extracts were determined by measuring their effects on reactive oxygen species (ROS) and pro-inflammatory cytokine production in vitro. The impact on intestinal barrier integrity was evaluated in Caco-2 cells and Drosophila melanogaster by examining leaky gut formation. Furthermore, a feeding trial using infected piglets was conducted to study the impact on the levels of superoxide dismutase, glutathione and lipid peroxidation. The Protect extract lowered ROS production in Caco-2 cells and reversed the stress-induced weakening of barrier integrity. The ROI extract inhibited the expression or secretion of interleukin-8 (IL-8), interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα). Moreover, the ROI extract decreased leaky gut formation and mortality rates in Drosophila melanogaster. Dietary supplementation with Protect improved the antioxidant status and barrier integrity of the intestines of infected piglets. In conclusion, wood lignan-enriched feed supplements are valuable tools that support intestinal health by exerting antioxidant, anti-inflammatory and barrier-strengthening effects.     

Self-Assembling Drug Formulations with Tunable Permeability and Biodegradability

This review focuses on key topics in the field of drug delivery related to the design of nanocarriers answering the biomedicine criteria, including biocompatibility, biodegradability, low toxicity, and the ability to overcome biological barriers. For these reasons, much attention is paid to the amphiphile-based carriers composed of natural building blocks, lipids, and their structural analogues and synthetic surfactants that are capable of self-assembly with the formation of a variety of supramolecular aggregates. The latter are dynamic structures that can be used as nanocontainers for hydrophobic drugs to increase their solubility and bioavailability. In this section, biodegradable cationic surfactants bearing cleavable fragments are discussed, with ester- and carbamate-containing analogs, as well as amino acid derivatives received special attention. Drug delivery through the biological barriers is a challenging task, which is highlighted by the example of transdermal method of drug administration. In this paper, nonionic surfactants are primarily discussed, including their application for the fabrication of nanocarriers, their surfactant-skin interactions, the mechanisms of modulating their permeability, and the factors controlling drug encapsulation, release, and targeted delivery. Different types of nanocarriers are covered, including niosomes, transfersomes, invasomes and chitosomes, with their morphological specificity, beneficial characteristics and limitations discussed.     

由聚合物结构预测气体的透过性能

本文利用基团加和法,对20多种常见聚合物的自由体积和内聚能进行了计算。发现氧气和氮气在聚合物膜中的透过率与自由体积和内聚能的比值有直接关系。此比值越大,气体的透过率越大,透过率的对数与自由体积和内聚能的比值基本呈线性关系。据此,对未知聚合物可根据其化学结构,从已有的基团数据计算该比值,从而预测它对氧气和氮气的透过性能。     

生物分配色谱:高通量筛选药物膜通透性和活性

生物分配色谱是指在色谱系统中引入类生物膜结构,以色谱学方法仿真药物与生物膜的相互作用,现已成为评估药物膜通透性和活性的高通量筛选模型。根据最新进展并结合课题组研究内容,对其理论基础、分类及应用进行了评述,并对这一领域的发展和前景进行了展望。