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Smaller Droplets (smaller + droplet)
Selected AbstractsEffects of surfactant and molecular weight of polyol on grating formation and switching of holographic PDLCPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11 2008S. S. Shim Abstract The interposition of surfactants between polymer and liquid crystal (LC) droplets was theoretically predicted by the positive spreading coefficient (0,<,,31) and utilized to interpret the morphology, grating formation kinetics, diffraction efficiency, and switching of the holographic polymer dispersed liquid crystal (HPDLC), prepared from various types (octanoic acid, poly oxyethylene octyl phenyl ether, and perfluoro-1-butanesulfonyl fluoride) and amounts (0,9 wt%) of surfactant and molecular weights of polyol (PPG). Regardless of the surfactant type, diffraction efficiency increased with the addition and increasing amount of surfactant, a tendency consistent with increasing value of spreading coefficient, which is determined by the formulations of grating formation. In contrast, diffraction efficiency showed a maximum with the polypropylene glycol (PPG) molecular weight. Surfactant effectively reduced the anchoring energy and electrically drove the film which otherwise was not driven. Overall, surfactant with greater ,31 gave smaller droplet, greater diffraction efficiency, driving voltage, contrast ratio, and smaller response time. Copyright © 2008 John Wiley & Sons, Ltd. [source] Flexibility in the composition and concentration of amino acids in honeydew of the drepanosiphid aphid Tuberculatus quercicolaECOLOGICAL ENTOMOLOGY, Issue 6 2002Izumi Yao Abstract 1. Mutualistic interactions between aphids and ants are mediated by honeydew that aphids produce. Previous work showed that when attended by the ant Formica yessensis Forel (Hymenoptera: Formicidae), nymphs of the aphid Tuberculatus quercicola (Matsumura) (Homoptera: Aphididae) developed into significantly smaller adults with lower fecundity than did nymphs that were not ant attended. 2. This study tested the hypothesis that this cost of ant attendance arises through changes in the quality and quantity of honeydew. Ant-attended and ant-excluded aphid colonies were prepared in the field. The composition and concentration of amino acids were compared between the honeydew produced by ant-attended colonies and that produced by ant-excluded colonies. 3. The aphids excreted smaller droplets of honeydew, but also excreted them more frequently, in ant-attended colonies than in ant-excluded colonies. The honeydew of ant-attended aphids contained more types of amino acid, and a significantly higher total concentration of amino acids, than did the honeydew of ant-excluded aphids. 4. These results suggest that the increase in the concentration of amino acids in honeydew leads to a shortage of nitrogen available for aphid growth and reproduction, resulting in lower performance under ant attendance. 5. With the advance of seasons, a significant reduction was found in both the total free amino acid concentration in phloem sap and the frequency of honeydew excretion; however the total concentration of amino acids in the honeydew did not vary significantly during the seasons, suggesting that aphids keep the quality of honeydew constant in order to maintain ant visitation. [source] Effect of oil content and processing conditions on the thermal behaviour and physicochemical stability of oil-in-water emulsionsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2009Megan Tippetts Summary The destabilisation mechanism of oil-in-water (o/w) emulsions was studied as a function of oil content (20% and 40% o/w), homogenisation conditions and crystallisation temperatures (10, 5, 0, ,5 and ,10 °C). A mixture of anhydrous milk fat and soya bean oil was used as the lipid phase and whey protein isolate (2 wt%) as emulsifier. Crystallisation and melting behaviours were analysed using differential scanning calorimetry. Physicochemical stability was measured with a vertical scan macroscopic analyser. Emulsions with 20% oil were found to be less stable than those with 40% oil. For 20% o/w emulsions, the crystallisation was delayed and inhibited in emulsions with smaller droplets and promoted in emulsions with larger droplets when compared with 40% o/w emulsions. Depending on the droplet sizes in the emulsion, the formation of lipid crystals (in combination with the emulsifier) either stabilises (small droplets) or destabilises (big droplets) the emulsion. [source] Microencapsulation of hydrophilic solid powder as fire retardant agent with epoxy resin by droplet coalescence methodJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Masanori Takahashi Abstract To give water resistance to Bistetrazol,diammonium (BHT,2NH3) as a fire retardant agent, microencapsulation with epoxy resin was tried by the droplet coalescence method. In this method, two kinds of epoxy resin droplets were prepared; one is the larger epoxy resin droplet containing BHT,2NH3 as a core material and the other the smaller droplets containing Imidazole as a gelation agent. The larger epoxy resin droplets were made to coalesce with the many smaller droplets during the microencapsulation process to prepare microcapsules. In the experiment, the agitation velocities for preparation of the droplets and for coalescence were mainly changed. With increase in the impeller speed, the content of core material increased, became maximum because of increase in the coalescence frequency, and then decreased because of breakup of droplets. With increase in the impeller speed, the leakage ratio of core material decreased, became minimum, and then increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008. [source] Recovery of lipase by adsorption at the n -hexadecane,water interfaceJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2003Hui-Min Wang Abstract A novel separation process based on the hydrophobic adsorption at the n -hexadecane,water interface was developed for the recovery of Acinetobacter radioresistens lipase from a pre-treated fermentation broth. In a mixture containing water, lipase and n -hexadecane, a water-in-oil emulsion was formed when the n -hexadecane-to-water ratio (o/w ratio) was larger than 3, and a large amount of lipase was found to be adsorbed at the interface. Compared with the oil-in-water emulsion (occurring when o/w ratio < 3), the water-in-oil emulsion generated smaller droplets and larger interfacial area, and was more stable. The harvested emulsion phase could be centrifuged to give an aqueous, concentrated lipase solution. Adsorption of lipase at the interface could be described by the Langmuir isotherm. For lipase concentrations ranging from 8.4 to 87.2 U cm,3, a single-stage adsorption resulted in a six- to four-fold concentration and 16,45% activity recovery, where lipase concentration was the dominant factor. A method using data from a single-stage adsorption to predict multiple-stage operation was described, and the agreement between the experimental and the predicted results was good. To improve the enzyme recovery, a multiple-run adsorption process was proposed. The use of salts enhanced the hydrophobic interaction between lipase and n -hexadecane. Advantages of the proposed process include simple operation, low operational cost, environmentally friendly, no requirement for pre-concentration of the enzyme solution, and negligible enzyme denaturation. Copyright © 2003 Society of Chemical Industry [source] | |||||||||||||