聚丙烯酰胺凝胶过程的影响因素

探讨了在高浓度氧化剂溶液中使用三价铬离子作交联剂制备聚丙烯酰胺凝胶的影响因素。研究了聚丙烯酰胺的用量、交联剂的配制、交联温度的影响、成胶粘度的变化等相关因素。     

聚乙烯醇缩丁醛冻胶化温度的测定方法

探讨了聚乙烯醇缩丁醛(PVB)冻胶化温度测定的方法。发现了用PVB甲醇溶液测定冻胶化温度较乙醇溶液更灵敏。方法准确可行。     

海藻酸凝胶性质对蛋白质扩散的影响

通过观察冷冻干燥海藻酸凝胶的断面扫描电镜(SEM)照片与卵清蛋白从海藻酸凝胶中的释放试验,分析了海藻酸凝胶性质对蛋白质在凝胶中扩散的影响。凝胶的SEM照片可见,海藻酸钙的冷冻干燥颗粒内为较大的圆孔,海藻酸锌凝胶内为较小的长孔,表明海藻酸锌高分子链在凝胶颗粒中的体积分率相对较大同时刚性较强;卵清蛋白从海藻酸凝胶颗粒中释放的试验结果表明,由于上述海藻酸锌凝胶的特性,导致海藻酸锌对卵清蛋白扩散阻滞作用相对较强;根据试验数据计算得卵清蛋白在海藻酸钙、海藻酸锌凝胶颗粒中的扩散系数分别为1.19×10-7、0.07×10-7cm2/s,利用阻滞模型计算得海藻酸锌高分子链在凝胶颗粒中体积分率约为海藻酸钙高分子链在凝胶颗粒中体积分率的1.7倍。     

Oxygen diffusivity in alginate/chitosan microcapsules

BACKGROUND: Oxygen diffusion properties affect the proliferation and metabolism of cells cultured in microcapsules with a polyelectrolyte complex membrane. The effective diffusion coefficient (De) of oxygen in alginate/chitosan (AC) microcapsules under different preparation conditions was calculated, and a mathematic model was developed to investigate the effect of oxygen diffusion on cell loading in the microcapsules. RESULTS: Oxygen De in AC microcapsules was independent of alginate solution concentration, intrinsic viscosity of alginate and different polyelectrolyte complex membranes. De decreased from 2.1 ± 0.3 × 10^?9 to 0.17 ± 0.01 × 10^?9 m² s^?1 as microcapsule diameter decreased from 1800 to 45 0 µm. Microcapsule density was increased from 1.013 ± 0.000 to 1.034 ± 0.003 g mL^?1 as diameter decreased from 1775 to 430 µm. The mathematic model results showed that critical CHO cell loadings were 1.8 × 10⁸ or 1.1 × 10⁸ cells mL^?1 in microcapsules with 450 or 1800 µm diameter, respectively. CONCLUSIONS: No significant difference was found of oxygen De between calcium alginate beads and AC microcapsules. The decrease of De with diameter was attributed to the increasing density and compact degree on the surface. The model results indicated that risk on necrosis rose with the increasing diameter. Microcapsules with smaller diameters may have more advantages on cell culture. © 2012 Society of Chemical Industry     

Self‐diffusion measurements of organic molecules in PDMS and water in sodium alginate membranes

The self‐diffusion of some organic molecules in silicone rubber and of water and water–ethanol mixtures in sodium alginate membranes was investigated to obtain information on the transport behavior in these systems. The temperature dependence of self‐diffusion was examined by the pulsed field gradient NMR technique. The experimental data confirm the homogeneous amorphous nature of PDMS and the affinity of silicone rubber to apolar solvents. The interrelations between solvent and polymer structures of the sodium alginate membrane varying the temperature have been obtained using differential scanning calorimetric. The results have been compared with the trend of self‐diffusion coefficients, and structure modifications of the membranes have been evidenced. The overall results confirm the potentialities of the technique used in measuring transport parameter in polymeric membranes. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1119–1128, 1999     

Gelling behavior of MgAl2O4 slurries with a common dispersant

MgAl₂O₄ transparent ceramics were shaped by a commonly used polyacrylic acid (PAA), which acted as both dispersant and gelling agent. The spinel slurries were prepared by ball-milling MgAl₂O₄ powder, PAA, and water in an attrition mill. The gelling of slurries happened at room temperature in air atmosphere without any other organic additive. The gelling mechanism was the formation of chelates between Mg²⁺ and carboxyl groups (-COO⁻) of PAA. The frequency-based testing method was applied to investigate the gelling process of the as-prepared slurry. In addition, a novel in situ characterization method based on a modified indentation testing was invented to better understand the strengthening of the wet green body with time and to guide when demolding could be carried out. After sintering, transparent MgAl₂O₄ ceramics with high in-line transmittance were resulted.     

高强度海藻酸盐纤维的制备

采用湿法纺丝方法制备高强度海藻酸盐纤维,研究了影响纤维断裂强度的因素。结果表明:海藻酸钠的β-D-甘露糖醛酸单元(M)/α-L-古罗糖醛酸单元(G)质量比越高,纤维断裂强度越低。采用M/G值为0.32的海藻酸钠为原料,氯化钙水溶液为凝固液,纺丝液质量分数为5.0%,凝固浴质量分数为4.5%,凝固浴温度为40℃,纤维烘干温度为30℃,可制得断裂强度达4.675 cN/dtex的高强度海藻酸盐纤维。     

Characterization of the structure and diffusion behavior of calcium alginate gel beads

A simple and novel method using gel shrinkage to indirectly characterize the structure of calcium alginate gel (CAG) beads during the calcium alginate gelation process was presented in this study. The effect of preparation process parameters (gelling cations, bead diameter, and alginate M _w and concentration) on the structure of the CAG bead formation process was thoroughly investigated. It was found that (a) the concentration of the Na⁺ and Ca²⁺ ion in gel bath was found to be the determining factor in the gel structure formation process by regulating the dissociation of alginate and the complexation of the calcium; (b) Na⁺ acts as a competitor with calcium and a screen in the electrostatic repulsion; (c) the effect of beads size below 700 μm on the structure of CAG beads can be neglected; and (d) the sodium alginate concentration has no significant effect on the gel formation process. Furthermore, the diffusion of bovine serum albumin (BSA) was controlled by the density of CAG bead. Consequently, a faster diffusion rate of BSA within the looser structure of beads can be observed. These results are keys to understanding the behavior and performance of beads in their utilization medium. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48923.     

胶凝剂对煤矸石多孔材料性能的影响

以周源山煤矿煤矸石作原料,硅溶胶作胶凝剂、十二烷基硫酸钠作发泡剂制备密度0.6 g/cm3的煤矸石多孔材料.研究了水固比对煤矸石料浆粘度和煤矸石多孔坯体干燥行为的影响,促凝剂对胶凝剂胶凝时间的影响,胶凝剂加入量对煤矸石多孔坯体与烧结体强度的影响,考察了样品断面的气孔形貌.结果表明,水固比为0.3时煤矸石料浆粘度为558.2 mPa·s、促凝剂占胶凝剂0.75wt％～1.0wt％,硅溶胶与煤矸石质量比为0.5时,泡沫浆料的胶凝时间满足操作要求,坯体干燥时不开裂;烧结体抗压强度为1.82 MPa,总气孔率72.6％,气孔分布均匀、孔径大小较为均一、约为100 μm.     

凝胶剂用量对胶印油墨性能的影响

采用有机铝型凝胶剂制备凝胶型连接料和胶印油墨,并研究了不同凝胶剂用量对连接料和胶印油墨的流变性能、印刷适性和乳化率的影响。试验结果表明:随着凝胶剂用量的增加,连接料和油墨的流动性能、黏弹性和触变性提高,并可有效减少飞墨,提高抗乳化能力,改善水墨平衡性能,使胶印油墨的流变性能更加适应高速印刷的要求。     

Regeneration of NADH in a bioreactor using yeast cells immobilised in alginate fibre. II: Detailed results

Saccharomyces cerevisiae cells were immobilised in calcium alginate fibres and used in a reactor as a source of alcohol dehydrogenase for the NAD⁺ to NADH reaction. Kinetic parameters were established for both the free enzyme and the fibre reactor. Detailed calculations for the free enzyme studies established the superiority of the Elmore–Kingston–Shields computer calculation of the initial rates. There was little difference between the Cornish-Bowden and the Hanes methods for subsequent generation of the kinetic parameters. Initial reaction rates that were obtained for the free enzyme gave kinetic parameters which were 65–80% below those obtained in the bioreactor. It is apparent that the diffusion limited the rate of reaction in the immobilised system. The bioreactor operated at high conversions at relatively low inlet concentrations of substrates. As the substrate concentration was raised the percentage conversion fell even though the amount of product produced overall rose substantially.     

改性壳聚糖水面溢油凝油剂的合成与性能

以壳聚糖、油酸酰氯、氯乙酸为、主要原料,合成了一种改性壳聚糖水面溢油凝油剂,并用IR对其结构进行了表征。实验结果表明：当壳聚糖：油酸酰氯：氯乙酸的摩尔比为1：1．3：1．5,油酰化温度为0-5℃,反应时间为3h,羧甲基化温度为50℃,反应时间为4h时,得到的凝油剂具有较好的凝油性能和较强的适应性,用于水面柴油、机油、苯、二甲苯的回收处理,不但回收处理效果好,而且基本不受水盐度的影响。     

Effect of bacterial alginate on growth of mesenchymal stem cells

Abstract

Capsular alginate was synthesized using bacteria Azotobacter agile 12 in order to test its potential for use in biotechnology and tissue engineering. Capsular bacterial alginate was isolated and purified using EDTA treatment and dialysis. Calcium alginate spheres were produced and their effect on growth of mesenchymal stem cells was studied. Bacterial alginate shows significantly lower cytotoxicity than commercial alginate isolated from algae.     

酸液胶凝剂丙烯酰胺/二甲基二烯丙基氯化铵的合成及性能评价

以二甲基二烯丙基氯化铵（DMDAAC）和丙烯酰胺（AM）为单体采用水溶液聚合的方法合成了一种酸液胶凝剂。研究了合成条件对该共聚物分子参数的影响，并对该共聚物用作酸液胶凝剂进行了评价实验。     

Physical Properties of Biodegradable Films of Soy Protein Concentrate/Gelling Agent Blends

Soy protein concentrate (SPC) is modified by blending with gelling agents such as agar, Agargel, and Phytagel and the properties of the blended films are characterized. Gelling agent addition significantly improves the mechanical properties, thermal stability, and moisture resistance. SPC blended with 30% PG show over 180% increase in the tensile stress and Young's modulus and the moisture regain decreases from 17.9 to 13.9%. The glass transition temperature of the SPC films increases from 132 to 148 °C after blending with Agargel and Phytagel. IPN‐like structure formation after adding gelling agents is responsible for the improvements. The results also suggest that the gelling agent chemistry determines the amount of gelling agent required to form IPN‐like structures.

     

Polymers beyond standard optical fibres – fabrication of microstructured polymer optical fibres

This paper reports the overall fabrication process of microstructured polymer optical fibres (mPOFs). mPOF fabrication involves a two‐step process: on the one hand, the design and creation of a preform containing a large‐scale version of the desired fibre and, on the other, the precise heating and drawing of the preform to the final fibre. The preforms are produced either by an improved drilling technique or by capillary stacking. For a correct and accurate drawing of the fibre, a controlled and precise heating unit has to be designed, an issue that will be explained in detail in this work. The quality and optical performance of the final mPOF depends strongly on key factors such as the preform annealing, the accuracy of the technique selected for the creation of the preform structure, the heating stage, as well as on the drawing parameters. All of them are analysed in detail and some drawn mPOFs of interest are reported as well. © 2018 Society of Chemical Industry     

Chemical analysis and microstructure examination of extended-pour alginate impression versus conventional one (characterization of dental extended-pour alginate)

Alginate impressions are not dimensionally stable. The recommended storage time for a conventional alginate is maximum 30?min. However, extended-pour alginate exhibits dimensional stability up to 100?h. For better understanding of the nature of extended-pour alginate, chemical analysis was performed by X-ray florescence spectrometer, compared to conventional alginate. Fourier transform infrared spectroscopy was used to determine the functional groups of both alginates. The organic content weights and microstructures were assessed. The higher Ca:Na ratio, lower organic content, and higher powder: water ratio might contribute in increasing the dimensional stability of the extended-pour alginate. Neither the functional groups nor the microstructure differed between both types.     

Absorption characteristics of alginate wound dressings

This study describes an investigation on the absorption characteristics of alginate wound dressings. The fluid that is absorbed by the dressing is divided into that which is held inside the fiber in the fiber structure and that which is held between the fibers in the textile structure. A number of dressings with different fiber structure and textile structure were studied and their effects on the absorption characteristics of the dressings were analyzed. It was found that a significant part of the absorption took place inside the fiber structure, in addition to the liquid held between fibers in the textile structure. High M alginate and high G calcium/sodium alginate fibers absorbed more fluid into the fiber than high G calcium alginate fiber, resulting in a better gelling ability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 953–957, 2004     

磷酸酯胶凝剂的合成及油基压裂液性能评价

探讨了油基压裂液胶凝剂磷酸酯的合成条件 ,进而对配制的压裂液性能进行了评价。实验结果表明 ,用所合成的磷酸酯胶凝剂配制的柴油基压裂液具有较快的交联速度、良好的耐温性能和耐温耐剪切性能以及快速破胶等综合性能 ,可用于强水敏性、低压低渗透地层的压裂改造。