Bile Enhances Cell Surface Hydrophobicity and Biofilm Formation of Bifidobacteria

Twenty-four human bifidobacterial strains were analysed for cell surface hydrophobicity (CSH) using a salt aggregation test (SAT) and a Congo red binding (CRB) assay. Three strains were selected for a systematic study on the CSH and biofilm formation: Bifidobacterium breve 46, Bifidobacterium animalis ssp. lactis 8:8 and a reference strain B. animalis ssp. lactis JCM 10602. CRB of the B. breve 46 and B. animalis ssp. lactis JCM 10602 was significantly enhanced (P?<?0.05) when grown in deMan–Rogosa–Sharpe cysteine (MRSC) broth supplemented with taurocholic acid (TA) or native porcine bile (PB). An enhanced CSH of the strains grown with PB and gastric mucin correlated with an increased mucin binding and an enhanced biofilm formation in prebiotic oligosaccharide-supplemented cultures. The three strains showed late bile-induced biofilm (72 h) under an anaerobic growth condition, and both B. animalis ssp. lactis strains showed a late bile-induced biofilm formation under aerobic conditions shown by crystal violet staining. These two strains were thus considered to be oxygen tolerant and more robust. Furthermore, enhanced biofilm formation of these robust bifidobacterial strains in the presence of prebiotics may allow for strong colonisation in the gastrointestinal tract when administered to in vivo models as a “synbiotic supplement”.     

pH-Responsive Aqueous Foams of Oleic Acid/Oleate Solution

Aqueous foams of oleic acid/oleate solution were found to be pH-responsive with pH changes. Detailed characterization of the aqueous foams of oleic acid/oleate solution was conducted with respect to their stability, structure, and pH response. The pH values required for foam circulation were studied through pH adjustment. The foaming and defoaming activities of oleic acid/oleate solution were explained by microscopic analysis and oil defoaming mechanisms. Because of the reversibility of oleic acid losing or receiving protons, the foaming and defoaming cycles could be readily repeated many times.      

分子模拟方法考察泡沫生成能力

采用分子模拟的方法研究表面活性剂的泡沫生成能力, 以界面形成能作为考察泡沫体系中液膜界面积的量化依据, 研究了泡沫液膜厚度、表面活性剂分子界面密度以及表面活性剂类型对泡沫液膜界面形成能计算的影响. 通过与实验结果相对应, 建立了界面形成能和泡沫生成能力之间的联系.     

十二烷基硫酸钠与甜菜碱在气液和油水界面的复配协同作用研究

研究了十二烷基硫酸钠（SDS）和甜菜碱（Betaine）以及复配体系在油水界面和气液界面的排布行为,探讨了温度、无机盐和复配比例对表面活性剂界面活性和泡沫稳定性的影响,重点探讨了多价无机阳离子对表面活性剂界面吸附行为和复配协同加合增效作用的影响,得到了海水为介质条件下两方面性能均较好的体系,取得的认识为高盐条件下低张力泡沫驱油体系的设计与应用提供理论依据和指导.     

Drainage of aqueous film-forming foam stabilized by different foam stabilizers

The present study focuses on the drainage property of aqueous film-forming foam stabilized by different types and concentrations of foam stabilizers. Aqueous film-forming foam (AFFF) formulation concentrates are prepared based on the main components of fluorocarbon surfactant, hydrocarbon surfactant, and organic solvents. Carboxymethylcellulose sodium (CS), xanthan gum (XG), and lauryl alcohol (LA) are selected as foam stabilizers of the AFFF. Surface tension, viscosity, and foamability tests of the AFFF solutions are conducted to evaluate the effect of foam stabilizers on the properties of AFFF solutions. Particularly, an apparatus is established based on the law of connected vessel in order to obtain the instantaneous mass of liquids drained from foams. The drainage features of the AFFFs containing different foam stabilizers are analyzed and compared with each other. The results indicate that AFFF drainage is significantly affected by the type and the concentration of foam stabilizers. The addition of CS and XG to AFFF results in a deceleration of foam drainage, while foam drainage is accelerated by the addition of LA. The variations of surface tension, viscosity, and liquid fraction of foams are the main reasons for the varying foam drainage rate. This study provides a direct connection between chemical components and fundamental properties of AFFF.     

智能水基泡沫研究进展

作为典型的软物质,水基泡沫因具有较小的粒径、较大的比表面积和良好的流动性而广泛应用于洗涤剂、化妆品、食品工程、油气开采等领域。在实际应用中,泡沫的稳定性起着制约性作用。近年来,在环境因素刺激下,能在稳定和非稳定状态之间转变的可控智能泡沫引起了极大关注。针对近年来智能水基泡沫的研究进展,本文综述了基于温度、磁场、光、pH和CO₂响应等智能水基泡沫体系,讨论了不同类型的智能水基泡沫的形成机理及相应性能,展望了智能水基泡沫的应用前景和发展方向。     

丝光沸石的疏水化研究

采用不同的脱铝方法得到Ｓｉ／Ａｌ比为１５～１１２的丝光沸石，用ＩＲ方法测定了样品的脱铝空穴含量，并考察样品的热稳定性和疏水性，实验结果表明，脱铝后形成的大量末端硅羟基仍有亲水性，因而单纯酸脱铝疏水化效果有限，用水蒸汽处理或（ＮＨ４）２ＳｉＦ６补硅的方法使沸石表面硅羟基转变成≡Ｓｉ－Ｏ－Ｓｉ≡键，能显著地提高沸石疏水性。     

介孔分子筛的表面硅烷化与疏水性

介孔分子筛的表面硅烷化与疏水性;介孔分子筛;有机硅烷化;疏水性;抗水解稳定性;废水处理     

Investigation on properties of aqueous foams stabilized by aliphatic alcohols and polypropylene glycol

Foams stabilized by nonionic surfactants are usually moderately stable due to high drainage rate and intense bubble coalescence and coarsening. This study aimed to investigate comparatively the foam properties of aliphatic alcohols (methyl isobutyl carbinol (MIBC) and 2-octanol) and polypropylene glycol (PPG400). Experiments were conducted using the FoamScan method at various surfactant concentrations and gas flow rates where the foam volume, liquid content of foam and foam half-life were determined. The results showed that both foamability and foam stability of surfactant solution increased with increasing gas flow rate and surfactant concentration for all tested surfactants. PPG400 was an unusually strong surfactant having the largest surface activity compared with MIBC and 2-octanol, which exhibited the maximum foaming performance and foam stability at all tested gas flow rates and concentrations. The present study suggested that foam properties depended primarily on the type of surfactant and its concentration and secondarily on the gas flow rate. In addition, properties of interface are closely related to that of foam, which is a significant point if one wants to produce foams for specific applications.     

Thermal Analysis of Micro- and Nano-Lignocellulosic Reinforced Styrene Maleic Anhydride Composite Foams

The aim of this study was to measure the thermal properties of foamed nano/macro filler–reinforced styrene maleic anhydride (SMA) composites. SMA (66%) as a polymer matrix (10% maleic anhydride content) and various fillers including wood flour, starch, α-cellulose, microcrystalline cellulose and cellulose nanofibrils as reinforcing agents (30%) and lubricant (4%) were used to manufacture the composites in a twin-screw extruder. According to the thermogravimetric analysis (TGA) results, thermal degradation of all the foamed composites was found to be lower than that of SMA composites. The storage modulus values were negatively affected with a second time foaming (reprocessing [recycling] the initially processed composites a second time), as were loss modulus and T_g. As a result, second-time-foamed composite modulus values were lower than those of the foamed composites. According to the melt flow index (MFI) results, viscosity of the SMA was found to increase with the addition of fillers.     

Influence of Temperature,Concentration, and Gas/Liquid Ratios on the Gas-Mobility Reduction of Foams in Porous Media

The gas-mobility reduction capability of sodium dodecylbenzene sulfonate foams was studied in sandpacks as a function of temperature at different surfactant concentrations and gas/liquid ratios. Increasing the temperature decreased the gas mobility at a given surfactant concentration and gas/liquid ratio. At any given temperature, the gas-mobility reduction was not increased beyond a certain limit with increasing surfactant concentration. While increasing the gas/liquid ratio improved the gas-mobility reduction at 20°C, at higher temperatures the reduction capability decreased after reaching a maximum at a gas/liquid ratio of 9. All the foams became weak at temperatures of 150°C and higher.     

Interfacial and Emulsion Stabilizing Properties of Indigenous Acidic and Esterified Asphaltenes

This article describes interfacial properties of acidic asphaltenes and their ability to stabilize emulsions. Asphaltenes extracted from crude oil were esterified with methanol to prevent ionization of carboxylic acid at high pH. Interfacial tension (IFT) between water and asphaltenes in xylene was significantly lower in basic than in acidic and neutral media, while the elasticity of the corresponding films was higher. These results are consistent with much more stable asphaltene-based emulsions in basic medium. For ester-asphaltenes, the IFT only showed a slight decrease under basic conditions and the interfacial elasticity was close to that in acidic solutions and only slightly higher than for neutral medium. While the asphaltene-stabilized emulsions showed a strong increase in stability in basic medium, this increase was much less for ester-asphaltene emulsions. Salt influenced the interfacial properties and generally reduced emulsion stability.     

Interfacial molecular array behaviors of mixed surfactant systems based on sodium laurylglutamate and the effect on the foam properties

The foam properties of mixtures of an eco-friendly amino-acid derived surfactant sodium lauroylglutamate (LGS) interacting with cationic surfactant dodecyl trimethyl ammonium bromide (DTAB), nonionic surfactant laurel alkanolamide (LAA) and anionic surfactant sodium dodecyl sulfonate (SDS), were investigated, respectively. It was amazing that the three investigated binary-mixed systems all showed obviously synergism effect on foaming, though LGS/DTAB catanionic mixture showed remarkable synergistic effect with no surprise. The equilibrium and dynamic surface activity, along with the interfacial molecular array behaviors of binary-mixed systems with different molar ratios at air/water surface were also studied. Moreover, the theoretical simulation was employed to investigate how the interfacial behaviors of surfactants at air/water surface affected the foam properties. The study might provide the meaningful guidance for utilizing the LGS-based systems, especially in constructing eco-friendly foam systems in the application areas of cosmetics, medicine and detergent.     

超低密度琼脂-明胶复合泡沫的研制

在探讨体系凝胶温度、冷冻速率、干燥温度及真空度等影响泡沫微观结构诸因素的基础上，确定出了琼脂－明胶复合泡沫制备工艺参数。以水作溶剂，成功地制得了密度≤1.0mg/cm^3,孔径≤100μm的琼脂－明胶泡沫；以水／1，4－二氧环己烷作混合溶剂，成功地制得了密度≤2mg/cm^3,孔径≤30μm的琼脂－明胶泡沫。热重－差热（TG－DSC）分析发现，琼脂－明胶复合泡沫的热稳定性可达－200℃。     

SIMULTANEOUS POLV(V1NVL ACETATE)/SILICA NETWORKS. INFLUENCE OF CROSSLINKING AGENTS

The modification of the rate or formation of interpenetrant simultaneous inorsjanic-organic (SIPIN) networks of poly(vinyl acetate) (PVAc)-SiO; was studied. The P(VAc) network was formod by radical polymerization with benzoyl peroxide in the presence of a crosslinked monomer, diethylen glycol bis maleate. SiO: network was obtained by sol-gel reaction of tetraethoxysilane (TEOS) catalyzed by radical polymeriznble acids: maleic acid (MA) and acrylic acid (AA) The reaction medium was the ethylic alcohol-water mixture. The formation rate of SIPIN depends on the ratio of initial organic over aqueous phases in case of caialysis by MA. The yelling limes for MA are higher than those for AA. This behavior inversely proponional to the acid strength is assigned to the selective interaction of the acids wiih the hydrocarbonated or aqueous zone of initial systems. Crotonic acid (CrA) is partitioned in the hydrocarbonate zone where TEOS also lies The glass transition temperature of organic network, P(VAc) increases with the increase of crosslinking agent concentration. It is higher in the network prepared in presence of MA owing to the higher number of hydrogen bonds induced by COOH.     

Spectral Properties of Foams and Emulsions

The optical and spectral properties of foams and emulsions provide information about their micro-/nanostructures, chemical and time stability and molecular data of their components. Foams and emulsions are collections of different kinds of bubbles or drops with particular properties. A summary of various surfactant and emulsifier types is performed here, as well as an overview of methods for producing foams and emulsions. Absorption, reflectance, and vibrational spectroscopy (Fourier Transform Infrared spectroscopy-FTIR, Raman spectroscopy) studies are detailed in connection with the spectral characterization techniques of colloidal systems. Diffusing Wave Spectroscopy (DWS) data for foams and emulsions are likewise introduced. The utility of spectroscopic approaches has grown as processing power and analysis capabilities have improved. In addition, lasers offer advantages due to the specific properties of the emitted beams which allow focusing on very small volumes and enable accurate, fast, and high spatial resolution sample characterization. Emulsions and foams provide exceptional sensitive bases for measuring low concentrations of molecules down to the level of traces using spectroscopy techniques, thus opening new horizons in microfluidics.     

Polymer Foams Stabilized by Particles Adsorbed at the Air/Polymer Interface

In aqueous systems, partially hydrophobic particles are known to stabilize foams even in the absence of any added surfactant. This paper shows that the same principle can be applied to polymeric systems: particles that are partially wetted by a polymer melt can stabilize a foam of that polymer. The foam stability is attributable to the adsorption of the particles at the air/polymer interface. Remarkably, stable foams are realized even from polymers that are liquid at room temperature, and hence are otherwise unfoamable. The implications of this result to practical foaming operations are discussed.

     

Effect of Lipid Phase State and Foam Film Type on the Properties of DMPG Stabilized Foams

The drainage and stability of DMPG (l-α-phosphatidyl-dl-glycerol dimyristoyl) foams were studied by a microconductivity method under conditions where three different foam film types could be formed—thin foam films (TFF), common black foam films (CBF), and Newton black foam films (NBF). Foaming properties were investigated at 20 and 28°C where DMPG is in the gel and liquid-crystalline states. Higher conductivity signals were observed at the higher temperature where DMPG was in the liquid-crystalline state, which is indicative of wetter or more stable foams under these conditions. This effect was observed independent of foam film type. However, for a given phase state, the type of foam films formed significantly influenced the stability and rate of drainage of the foam. Indeed, the water content of the foams, obtained under conditions for formation of different foam films, is ranked in the order TFF > CBF > NBF. When the temperature was increased to 28°C (i.e., in the liquid-crystalline state), CBF and NBF showed a slight decrease in film thickness and an increase in film lifetime and surface molecular diffusion coefficient in the adsorbed layer. It is likely that the fluidity of the interfacial layer is an important factor contributing to DMPG foam stabilization.     

Determination of Halogenated Hydrocarbons in Insulating Polymeric Foams

A simultaneous thermal analysis/mass spectroscopy system was used for the determination of halogenated hydrocarbons in polymeric foam insulation materials. The investigation of ten different polymeric foams show that this equipment is a sensitive and reliable tool for the identification and determination of the bubbling agent. The results are compared with the Purge and Trap method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal and mechanical interfacial properties of the DGEBA/PMR-15 blend system

In this work, the blend system of diglycidyl ether of bisphenol A and PMR-15 polyimide is investigated in terms of thermal and dynamic mechanical interfacial properties of the casting specimens. The thermal stabilities are studied by thermogravimetric and thermomechanical analyses, and the dynamic mechanical properties are carried out by dynamic mechanical analysis. The results show that the thermal stabilities based on the initial decomposition temperature, the integral procedural decomposition temperature, and the glass transition temperature are increased with increasing PMR-15 content. The crosslinking density (rho) of the blend system is increased at 10 phr of PMR-15, compared with that of neat epoxy. Mechanical interfacial properties measured in the context of critical stress intensity factor and critical strain energy release rate show similar behaviors with E(a) and rho, probably due to the increase in intermolecular interactions or hydrogen bondings in polymer chains.