Adsorptive polyHIPE composites based on biosorbent immobilized nanoclay: Effects of immobilization techniques

Styrene/divinyl benzene‐based macroporous polyHIPE composites were prepared from water‐in‐oil (w/o) high internal phase emulsion (HIPE) templates by using both organo‐modified montmorillonite (MMT) and a nonionic surfactant. For this purpose, Spirulina (Sp) microalgae was immobilized onto Na‐MMT clay by using two different modification techniques. They are based on conventional adsorption in solution (SOL) and novel cryoscopic expansion (C‐XP) assisted adsorption. Highly porous nanocomposites were prepared by using different percentages of modified nanoclays (SpSOLM/SpXPM) with a constant internal phase volume of 80%. The emulsion stability, morphology, and dye adsorption capacities were discussed by paying attention to nanoclay immobilization techniques, clay loading degree and surfactant concentration. The critical amount of nonionic surfactant for formation of the stable neat HIPE template was found to be only 5 vol% with respect to volume of organic phase. However, this amount was further reduced to much less value (2 vol%) with Sp immobilized nanoclays via help of cooperative interactions of Sp and MMT nanoclay. The C‐XP assisted modification of clay led to nanocomposites with 580% higher adsorption capacity for cationic dye. This remarkable benefit was obtained with even 0.5% clay loading and only 2% surfactant concentration. POLYM. ENG. SCI., 58:1229–1240, 2018. © 2017 Society of Plastics Engineers     

Porous dye affinity beads for albumin separation from human plasma

Porous polymeric beads were obtained by the suspension polymerization of 2‐hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA). Poly(HEMA–EGDMA) beads were characterized by surfacearea measurements, swelling studies, FTIR, scanning electron microscopy (SEM), and elemental analysis. Poly (HEMA–EGDMA) beads had a specific surface area of 56 m²/g. SEM observations showed that the poly(HEMA–EGDMA) beads abounded macropores. Poly(HEMA–EGDMA) beads with a swelling ratio of 55%, and containing different amounts of Reactive Red 120 (9.2–39.8 μmol/g) were used in the adsorption/desorption of human serum albumin (HSA) from aqueous solutions and human plasma. The nonspecific adsorption of HSA was very low (0.2 mg/g). The maximum HSA adsorption amount from aqueous solution in phosphate buffer was 60.1 mg/g at pH 5.0. Higher HSA adsorption value was obtained from human plasma (up to 95.7 mg/g) with a purity of 88%. The equilibrium monolayer adsorption amount, Q_max was determined as 172.4 mg/g. The dimensionless separation factor (R_L) value shows that the adsorption behavior of HSA onto the Reactive Red 120 attached poly(HEMA–EGDMA) beads was favorable (0 < R_L < 1). Desorption of HSA from Reactive Red 120 attached poly (HEMA–EGDMA) beads was performed using 0.1M Tris/HCl buffer containing 0.5M NaCl. It was observed that HSA could be repeatedly adsorbed and desorbed with Reactive Red 120‐attached poly(HEMA–EGDMA) beads without significant loss in the adsorption amount. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Bio‐based polymer nanocomposites based on layered silicates having a reactive and renewable intercalant

Soybean oil‐based polymer nanocomposites were synthesized from acrylated epoxidized soybean oil (AESO) combined with styrene monomer and montmorillonite (MMT) clay by using in situ free radical polymerization reaction. Special attention was paid to the modification of MMT clay, which was carried out by methacryl‐functionalized and quaternized derivative of methyl oleate intercalant. It was synthesized from olive oil triglyceride, as a renewable intercalant. The resultant nanocomposites were characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of increased nanofiller loading in thermal and mechanical properties of the nanocomposites was investigated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The nanocomposites exhibited improved thermal and dynamic mechanical properties compared with neat acrylated epoxidized soybean oil based polymer matrix. The desired exfoliated nanocomposite structure was achieved when the OrgMMT loading was 1 and 2 wt % whereas partially exfoliated nanocomposite was obtained in 3 wt % loading. It was found that about 400 and 500% increments in storage modulus at glass transition and rubbery regions, respectively were achieved at 2 wt % clay loading compared to neat polymer matrix while the lowest thermal degradation rate was gained by introducing 3 wt % clay loading. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2031–2041, 2013     

Effects of the nature and combinations of solvents in the intercalation of clay with block copolymers on the properties of polymer nanocomposites

Polystyrene (PS) nanocomposites were prepared by the free‐radical polymerization of styrene in the presence of organically modified montmorillonite (MMT) clays. MMT clay was modified with a low‐molecular‐weight and quarternized block copolymer of styrene and 4‐vinylpyridine [poly(styrene‐b‐4‐vinylpyridine) (SVP)] with 36.4 wt % PS and 63.6 wt % poly(4‐vinylpyridine) (P4VP). Special attention was paid to the modification, which was carried out in different compositions of a solvent mixture of tetrahydrofuran (THF) and water. The swelling behavior of the MMT clay was studied by an X‐ray diffraction technique. The diffraction peak shifted to lower 2θ angles for all of the modified clays, which indicated the intercalation of the quarternized SVP copolymer into the MMT layers in different degrees. Higher interlayer distances, which showed a high degree of block copolymer insertion, were obtained for solvent compositions with THF in water. The resultant nanocomposites were characterized by X‐ray diffraction, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, and dynamic mechanical analysis. The desired exfoliated nanocomposite structure was achieved when the MMT modification was conducted in 50 or 66 wt % THF, whereas the other modifications all resulted in intercalated structures. The resulting exfoliated nanocomposite was found to have better thermal stability and dynamic mechanical performance compared to the others, even with 2% clay loading. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Redirection of Pyruvate Pathway of Lactic Acid Bacteria to Improve Cheese Quality

Metabolic engineering in Lactic acid bacteria (LAB) has focused on changing of pyruvate metabolism to increase production of desired flavor compounds. A constructed mutant strain should contain no foreign DNA and antibiotic resistance genes. Therefore, food grade lactate dehydrogenase (ldh ^d) and diacetyl reductase (dar ^d) mutant strains were created using two plasmid system in this study. Metabolic end products (pyruvate, lactate, formate and acetoin) of these strains in glucose medium and in cheese were determined using HPLC. Created mutant and wild type strains were used as a starter culture in cheese. Compared to the wild type strain, different levels of metabolites were observed in cheese during three weeks of ripening. The ldh ^d strains produced less lactate but high acetoin as a result of gene deletion. Deletion of dar gene decreased the production of acetoin. The dar deficient strains have low diacetyl reductase activity and are able to reduce significant amounts of acetoin but not terminate it completely. Genetic modification made the shift from homolactic to mixed acid fermentation, but the desired compound production hardly improved. The basis of these results and techniques are promising for the further studies.     

蜂蜜对代谢综合征的作用机制研究进展

代谢综合征是机体以胰岛素抵抗为核心,发生碳水化合物、脂肪、蛋白质等物质代谢紊乱,进而导致肥胖、血脂异常、心血管疾病等症候群的病理状态,现已成为威胁人类健康的重要因素。蜂蜜富含糖类、酚类等营养成分,具有抗氧化、抗炎、抑菌等多种生物活性,大量研究表明蜂蜜可以缓解代谢综合征,并对肠道菌群有调节作用。本文从胰岛素抵抗、调节糖脂蛋白代谢途径的机制和调节肠道菌群等方面阐述蜂蜜及其活性成分对代谢综合征的缓解作用,综述蜂蜜对代谢综合征作用机理的相关研究进展,旨在为代谢综合征的综合防治和功能性蜂蜜产品的开发提供理论依据。     

NREL VI rotor blade: numerical investigation and winglet design and optimization using CFD

The main objectives of this study were to aerodynamically design and optimize a winglet for a wind turbine blade by using computational fluid dynamics (CFD) and to investigate its effect on the power production. For validation and as a baseline rotor, the National Renewable Energy Laboratory Phase VI wind turbine rotor blade is used. The Reynolds‐averaged Navier–Stokes equations are solved, and k–ε Launder–Sharma turbulence model was used. The numerical results have shown a considerable agreement with the experimental data. The genetic algorithm was used as the optimization technique with the help of artificial neural network to reduce the computational cost. In the winglet design, the variable parameters are the cant and twist angles of the winglet and the objective function the torque. Multipoint optimization is carried out for three different operating wind speeds, and a total of 24 CFD cases are run in the design. The final optimized winglet showed around 9% increase in the power production. Copyright © 2013 John Wiley & Sons, Ltd.     

快速配体交换法制备水溶性磁性Fe3O4纳米粒子

为了获得水溶性Fe_3O_4纳米粒子,以聚乙二醇(PEG)磷酸酯为亲水性配体,在甲苯/四氢呋喃/水三元混合溶剂体系下通过快速配体交换法将油酸包覆的油溶性磁性Fe_3O_4纳米粒子转变成聚乙二醇磷酸酯包覆的水溶性Fe_3O_4纳米粒子。考察了四氢呋喃等溶剂在实现快速配体交换中所起到的作用。利用透射电子显微镜(TEM)、动态光散射(DLS)、X射线粉末衍射仪(XRD)、傅立叶红外光谱仪(FTIR)、振动样品磁强计(VSM)对磁性Fe_3O_4纳米粒子进行了分析表征。结果表明:四氢呋喃可以促进PEG磷酸酯与Fe_3O_4纳米粒子表面的有效接触并使得油酸分子从纳米粒子表面快速地脱附下来,此外,还消除了配体交换过程中出现的乳化效应。四氢呋喃的应用实现了快速配体交换法制备水溶性PEG磷酸酯包覆的磁性纳米粒子。     

进排气结构参数对微型自由活塞发动机扫气过程影响的数值模拟研究

在微型自由活塞动力装置单缸压燃的研究下,结合单次冲击燃烧可视化试验,针对简化模型的进排气口间距L、进气道倾角α、排气道倾角β,进气道孔径Din及排气道孔径Dout展开数值模拟计算以应用于双气缸研究中,使整个运行工况更加平稳且高效.当进、排气口间距不断增大,其换气过程的扫气效率逐渐下降;进气口与排气口的扫气角成一定夹角时...