Influences of combustion improver content and motionless time on the stability of two-phase emulsions

The heavy molecular bonds of liquid fuels can be broken with the assistance of a nitromethane fuel additive by virtue of its explosive and flammable properties to obtain greater heat release. Because of the immiscibility between nitromethane and petro-diesel, two-phase emulsions of nitromethane dispersed in the oil phase of a mixture of diesel and biodiesel were prepared. The experimental results show that microwave irradiation produced an emulsion with a larger number of dispersed nitromethane droplets in the continuous oil mixture, a smaller mean droplet size, and lower turbidity than magnetic stirring, and thus was a better method for preparation of the two-phase emulsion. The increase in the nitromethane weight fraction increased the number of dispersed nitromethane droplets and the emulsion turbidity. In addition, allowing the emulsion preparation to remain motionless for a longer period of time after either method resulted in an obvious reduction in the emulsification stability (ES).     

环氧-聚氨酯复合乳液的合成及表征

以甲苯二异氰酸酯(TDI-80)、聚醚二醇(N220)、二羟甲基丙酸(DMPA)、环氧树脂为主要原料,合成了环氧-聚氨酯复合乳液。主要讨论了环氧树脂对水性聚氨酯乳液及其涂膜性能的影响。实验结果表明,环氧-聚氨酯乳液的表面张力、粘度,涂膜的硬度、耐水性及力学性能随着环氧树脂用量的增大而增强,但乳液外观和稳定性变差,故适宜的环氧树脂添加量为4%～8%。采用傅里叶变换红外光谱、粒径分析仪、凝胶渗透色谱(GPC)、透射电镜(TEM)对乳液和涂膜进行了表征。傅里叶变换红外光谱分析表明,环氧树脂的环氧基和羟基都参与了反应。粒径分析仪和凝胶渗透色谱分析显示,加入环氧树脂后,水性聚氨酯(WPU)分散体粒径和分子量增大,粒径分布和分子量分布均变宽。     

Polymeric porogens used in the preparation of novel monodispersed macroporous polymeric separation media for high-performance liquid chromatography.

A novel approach to monosized macroporous polymeric separation media with vastly enhanced pore size distributions and chromatographic properties has been developed. Key to this approach is the combined use of monodispersed polymeric particles and suitable solvents as porogens in the copolymerization of styrene and divinylbenzene. Following polymerization, the polymeric porogen is dissolved, leaving behind the monosized beads with a controlled pore structure. The exact pore size and pore size distribution of the final beads are largely controlled by the amount of soluble polymer in the polymerizing mixture: the larger the proportion of soluble polymer in the system, the larger the pores. The uniformly sized macroporous beads prepared with an optimized ratio of polymeric and low molecular weight porogens proved to be very efficient even in short columns for the separation of polystyrene standards in the SEC mode and the separation of proteins in the reversed-phase mode. The relationship between pore size and specific surface area, on one hand, and chromatographic properties of the stationary phase, on the other, have been clearly documented.     

Molecularly imprinted polymer beads: suspension polymerization using a liquid perfluorocarbon as the dispersing phase

A suspension polymerization technique suitable for molecular imprinting is described, based on the use of a liquid perfluorocarbon as the dispersing phase. This dispersant does not interfere with the interactions between functional monomers and print molecules required for the recognition process during molecular imprinting. The method produces polymer beads, with almost quantitative yield, which can be used after only a simple washing step. An acrylate polymer with perfluorocarbon and poly(oxyethylene) ester groups was used to stabilize an emulsion of functional monomer, cross-linker, print molecule, initiator, and porogenic solvent in perfluoro(methylcyclohexane). Initiation of polymerization by UV irradiation resulted in polymer beads. The average bead size could be controlled between about 50 and 5 μm by varying the amount of stabilizing polymer. SEM of the beads indicated spherical particles with morphology typical of beads made by suspension polymerization. The technique was applicable to a range of conditions typically used for molecular imprinting. A detailed chromatographic study of the polymer beads confirmed that α values and resolution factors were similar to those achieved with traditional ground and sieved imprinted polymers. Small (5 μm) beaded packings gave low back pressure and rapid diffusion, giving good separation even at high flow rates.     

环氧树脂改性水性聚氨酯的合成研究

采用甲苯二异氰酸酯(TDI-80)、聚醚二醇(N220)、二羟甲基丙酸(DMPA)、环氧树脂和丙烯酸羟丙酯(HPA),合成了环氧改性的双键封端水性聚氨酯乳液.乳液由于含有不饱和双键而具有感光性能,故此乳液可用作水性紫外光固化涂料或胶粘剂的预聚物.实验结果表明,随着环氧树脂用量的增大,涂膜的硬度、耐水性、耐溶剂性及力学性能增强,但乳液外观和稳定性变差,故适宜的环氧树脂添加量为4%～8%.通过傅立叶变换红外光谱、粒径分析仪、凝胶渗透色谱(GPC)和透射电镜(TEM)等对乳液进行了表征.粒径分析仪分析显示,加入环氧树脂后,水性聚氨酯(WPU)分散体粒径增大,粒径分布变宽.凝胶渗透色谱分析表明环氧树脂改性水性聚氨酯提高了聚氨酯的分子量.     

Removal of organic compounds by alginate gel beads with entrapped activated carbon

The adsorption of alginate gel (AG) beads and AG with activated carbon entrapped (AG–AC) beads prepared using different types of metal ions were investigated by measuring the removal of several organic compounds with different charges and size. AG–AC beads prepared in a CaCl₂ solution adsorbed strongly positively charged compounds as well as electrically neutral and low molecular weight compounds such as p-chlorophenol. However, a high molecular weight humic acid was not adsorbed by AG–AC. The AG–AC selectively adsorbed p-chlorophenol from a humic acid solution. The adsorption capacity obtained from the adsorption isotherm of AC entrapped in AG was compared with that of AC. The AG–AC beads prepared in a solution of FeCl₃ were able to specifically adsorb negatively charged gallic acid. Thus, entrapping AC into AG resulted in the selective adsorption.     

复合表面活性剂对油包水型高内相乳状液流变性和稳定性的影响

为了研究复合表面活性剂对油包水型高内相乳状液流变性和稳定性的影响,选用由PIBSA-TEA和油酸二乙醇酰胺、椰子油酸二乙醇酰胺、失水山梨醇单油酸酯等小分子表面活性剂组成的复合表面活性剂制备HCEs,并检测所制得HCEs的流变性和储存稳定性。结果表明:表面活性剂对HCEs的剪切应力和储能模量有较大的影响。采用复合表面活性剂制备的HCEs具有较高的剪切应力和储能模量。但是,复合表面活性剂制备的HCEs储存稳定性明显下降。在油相黏度比较高时,复合表面活性剂制备的HCEs储存稳定性有一定的提高。     

Development of a Novel Parenteral Formulation for Tetrazepam Using a Lipid Emulsion

A novel parenteral formulation for tetrazepam (10 mg/ml) was developed using lipid emulsions. This formulation utilized a new lipid emulsion formulation, which was developed by changing the polarity of the oil phase. It was found that increasing the polarity of the oil phase resulted in enhanced solubility of tetrazepam. Tetrazepam showed higher solubility in a mixture of castor oil and middle-chain triglycerides (MCTs) (1:1) than in any other oil investigated. This mixture resulted in low interfacial tension and moderate viscosity, which seemed to be the optimum oil phase. In addition, to increase the concentration of tetrazepam, an emulsion formulation containing 30% oil phase was produced and optimized. The drug-free emulsion formulation showed fine particle sizes with an imperceptible change in physicochemical properties after more than 2 years on the shelf. As a result, it was possible to produce a parenteral emulsion formulation containing 10 mg/ml tetrazepam. No change in the physicochemical properties of the emulsion was observed after the addition of tetrazepam. The tetrazepam emulsion showed stable behavior during the autoclaving process and good shelf stability for at least 10 months as well. Tetrazepam itself also displayed good stability during the autoclaving process and also showed good shelf stability in this emulsion formulation.     

A new controlled-release liquid delivery system based on diclofenac potassium and low molecular weight chitosan complex solubilized in polysorbates

A complex of low molecular weight chitosan (LMWC) with oleic acid and diclofenac potassium (DP) was prepared and dispersed in high concentrations of polysorbate 20, 60 and 80 in water to form a solution which releases its components slowly. The formed complex was characterized using different analytical methods. The size of the resulted nanoparticles and the effect of tweens on size were followed using dynamic light scattering (DLS). The release of DP from this delivery system was monitored by altering the molecular weight of chitosan and the type and concentration of the polysorbates used. The most suitable preparation consisted of DP, LMWC 13?kDa, and oleic acid. This was dispersed in 5% Tween 80 and the release was followed by the adaptation of USP II apparatus using a cellophane bag. This preparation offers a release of up to 24?h.     

Remediation of groundwater contaminated with DNAPLs by biodegradable oil emulsion

Emulsion-based remediation with biodegradable vegetable oils was investigated as an alternative technology for the treatment of subsurface DNAPLs (dense non-aqueous phase liquids) such as TCE (trichloroethylene) and PCE (perchloroethylene). Corn and olive oil emulsions obtained by homogenization at 8000rpm for 15min were used. The emulsion droplets prepared with corn and olive oil gave a similar size distribution (1-10microm) and almost all of initially injected oil, >90%, remained in a dispersed state. In batch experiments, 2% (v/v) oil emulsion could adsorb up to 11,000ppm of TCE or 18,000ppm of PCE without creating a free phase. Results of one-dimensional column flushing studies indicated that contaminants with high aqueous solubility could be efficiently removed by flushing with vegetable oil emulsions. Removal efficiencies exceeded 98% for TCE and PCE with both corn and olive oil emulsions. The results of this study show that flushing with biodegradable oil emulsion can be used for the remediation of groundwater contaminated by DNAPLs.     

Removal of dyes and their mixtures from aqueous solution using liquid emulsion membrane

Extraction of dyes from aqueous solution was studied using liquid emulsion membrane. Study was carried out using two dyes, namely, crystal violet (CV) and methylene blue (MB). Extraction of single component system of each dye and their binary mixture were investigated. Liquid emulsion membrane was formed using n-heptane as membrane phase, sodium hydroxide solution as the internal phase and dye solution as the external phase. Surfactant span 80 was used as the emulsion stabilizer. Effects of concentration of span 80, concentration of NaOH, stirring speed, composition of feed solution and the volume ratio of the oil phase to the aqueous phase (O/A) were studied in detail both for single and binary system. Maximum extraction of MB was found to be 99% and that for CV was about 95% in single component system. In binary mixture, these values were 97% and 90%, respectively.     

Pulsed laser spot welding of intersection points for Zircaloy-4 spacer grid assembly

A pulsed laser spot welding technology has been developed for joining intersection points of 0.457 mm-thick Zircaloy-4 straps. Weld beads size, mechanical properties and microstructure characterization of the weld beads were investigated. The results indicate that peak power of the pulsed laser has significant influence on the penetration depth of weld beads. Pulse width and number of shots should be taken into consideration mainly to control the weld width. The average value of ultimate tensile loads of the intersection points are continuously increasing as the penetration depth and weld width of weld beads increase. Fracture was located at the fusion line and the fracture surface could be characterized as a mixture of ductile and cleavage feature. Column grains and equiaxed grains were observed in fusion zone and heat affected zone, respectively. The fusion zone consists of a mixture of α-Zr and β-Zr phases among which lamellar Widmanstatten structure α-Zr + Zr₃Fe was distributed. The Zr(Fe, Cr)₂ second phase particles were precipitated inter and intragranular of α-Zr grains.     

Chitosan composite films. Biomedical applications

Chitosan acetate films have been prepared using chitosans from shrimps (Pleuroncodes monodon) of low and high molecular weight (LMv = 68,000 g/mol and HMv = 232,000 g/mol) and deacetylation degree of 80 and 100%, respectively. The chitosan films were obtained by addition of several additives to acetic acid chitosan solutions, such as: glycerol, oleic acid and linoleic acid in different proportions. The pH of the solutions before casting ranged from 5.0 to 6.0. The composite film thickness are reported. The films have been analyzed by FTIR showing characteristic bands corresponding to the additives. The scanning electron microscopy (SEM) studies reveals the different morphology of the composite films. The films exhibit different physical properties depending upon the additives and/or mixture of them. The addition of glycerol to composite improves the elasticity of the films. The swelling in glucose and saline solutions for several films was evaluated, being higher in the glucose solution. The bactericide test against Staphylococcus aureus, Pseudomona aeruginosa and Acinetobacter baumanii in plates with either blood and or agar tripticase showed that the molecular weight influences on the bactericidal properties of the chitosan composite films and over its effect against gram positive and gram negative bacteria. Medical applications of the composite films were done in patients with burns, ulcers and injuries, the films containing glycerol showed good adhesion in comparison with those without it. The composite films tested were mainly three (1) chitosan acetate with glycerol, (2) chitosan acetate with oleic acid and (3) chitosan acetate with glycerol and oleic acid. Excellent results in the skin recovery were obtained after 7–10 days. Since the chitosan is biodegradable by the body enzymes it does not need to be removed and increases the gradual grows of the damage tissues.     

丙烯酸酯对水性聚氨酯乳液及其塑料凹版油墨的性能的影响

采用乳液共聚法制备了聚氨酯-聚丙烯酸酯(PUA)复合乳液,并以酞菁蓝为颜料配制了塑料凹版水性油墨,讨论了乙烯基单体甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)对PUA 乳液及其水性油墨的性能的影响.结果表明,随着MMA含量的增加,PUA复合乳液的粘度先减小然后增大.随着m(BA)/m(MMA)的增加,PUA乳液的粘度先变大随后减小.用固含量为30%(质量分数,后同)的PUA乳液配制的水性油墨的粘度随时间推移而增大.水性油墨的初干性随MMA与聚氨酯(PU)的质量比的增加而变好,但随着m(BA)/m(MMA)的增加而变差.当MMA与PU的质量比达到0.25后,水性油墨不仅对PET薄膜具有优异的附着牢度,对OPP薄膜也有良好的附着牢度,同时具有良好的耐水耐酸性能.     

Effect of Surfactant Agents on the in Vitro Release of Insulin from DL-PLA Microspheres

This paper describes the effect of surfactants on the in vitro release profile of bovine insulin from DL-polyacetic acid (DL-PLA) microspheres prepared by the double-emulsion technique. The surfactants, Tween®-80 and Span®-60, were included in the water and oil phases, respectively, of the first emulsion. The presence of these agents affected the burst effect but not the subsequent release phase. The latter is more controllable by PLA molecular weight selection, with slower release being achieved as the molecular weight increases.     

Effects of three parameters on the diameter of electrospun poly(ethylene oxide) nanofibers

The combined use of two techniques namely electrospray and spinning is made use in a highly versatile technique called electrospinning, which produces the diameter of polymer fibers range from nanometer to sub-micron. In this work, we have studied effects of adding LiCl on the morphology and diameter of electrospun poly(ethylene oxide), and we have also evaluated systematically the effect of three important solution parameters on the morphology of electrospun poly(ethylene oxide): molecular weight, solution viscosity and electrical conductivity. We find that molecular weight is strongly correlated with the formation of bead defects in the fibers, the smaller molecular weight, the more beads defect density. As a result, the fibers have beads-in-string structures. Electrical conductivity increases, then decreases as molecular weight increases. Solution viscosity has been found to most strongly affect fiber size, with fibers diameter increasing with increasing solution viscosity according to a power law relationship. In addition, we find evidence that solution viscosity and electrical conductivity affect the interesting morphology of the electrospun nanofibers, and result in doubling and forming membrances phenomena.     

Oleic-acid-coated CoFe2O4 nanoparticles synthesized by co-precipitation and hydrothermal synthesis

Oleic-acid-coated CoFe₂O₄ nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism dominates to the region where mono-domain ferrimagnetism dominates the magnetic properties.     

油水相界面张力对乳化炸药性能的影响

采用白金环法测定了乳化炸药复合油相与硝酸铵水溶液的界面张力,并研究了乳化剂质量分数、温度、分子结构和热值对油水相界面张力的影响以及界面张力对乳胶基质微观结构和储存稳定性的影响。结果表明,随着乳化剂质量分数的升高,界面张力先下降后保持恒定;随着温度升高,界面张力呈线性下降趋势;复合蜡组分的异构化烷烃含量越高,环状化合物越少,热值越低,油水相界面张力越低。随着界面张力和临界质量分数的降低,乳胶基质的粒径减小。乳胶基质的储存稳定性随着油相材料界面张力的降低而增强。     

Characterisation of physico-mechanical properties and degradation potential of calcium alginate beads for use in embolisation

High molecular weight alginate beads with 59% mannuronic acid content or 68% guluronic acid were prepared using a droplet generator and crosslinked in calcium chloride. The alginate beads were compared to current embolisation microspheres for compressibility and monitored over 12 weeks for size and weight change at 37°C in low volumes of ringers solutions. A sheep uterine model was used to analyse bead degradation and inflammatory response over 12 weeks. Both the in vitro and in vivo data show good delivery, with a compressibility similar to current embolic beads. In vitro, swelling was noted almost immediately and after 12 weeks the first signs of degradation were noted. No difference was noted in vivo. This study has shown that high molecular weight alginate gel beads were well tolerated by the body, but beads associated with induced thrombi were susceptible to inflammatory cell infiltration. The beads were shown to be easy to handle and were still observable after 3 months in vivo. The beads were robust enough to be delivered through a 2.7 Fr microcatheter. This study has demonstrated that high molecular weight, high purity alginate bead can be considered as semi-permanent embolisation beads, with the potential to bioresorb over time.     

表面活性剂浓度对乳胶基质平均粒径的影响和机理分析

乳胶基质内相液滴的平均粒径大小直接反映了可燃剂和氧化剂的混合均匀程度,是影响乳化炸药爆炸性能和稳定性能的重要因素。主要研究了油相中表面活性剂浓度对乳胶基质内相液滴平均粒径的影响。使用5种含有不同表面活性剂浓度的外相材料制备乳胶基质,并且使用激光粒度仪测试了所有样品的平均粒径。实验结果表明:油相材料中表面活性剂的浓度越大,则制备出的乳胶基质平均粒径越小。然后通过表面张力的理论分析和外相动力粘度的实验测试,进而分析出增加表面活性剂降低乳胶基质的平均粒径的机理:表面活性剂的增加导致了外相材料的动力粘度的增大,进而使乳胶基质平均粒径变小,和表面张力无关。