Home About us Contact
|
Home About us Contact | ||
|
|
||
Oil Droplets (oil + droplet)
Selected AbstractsHisto-cytochemistry and scanning electron microscopy of lavender glandular trichomes following conventional and microwave-assisted hydrodistillation of essential oils: a comparative studyFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2006Marcello Iriti Abstract The conventional hydrodistillation method (HD) has been compared with three different variants of the microwave-assisted hydrodistillation technique (MADH), on Lavandula angustifolia flowers, both in terms of oil yield and effects on the glandular trichome morpho-structure. The amount and composition of essential oil extracted in 4 h by HD was similar to that obtained in only 20 min by MADH and even lower than that extracted with a steam variant (MASD) of MADH itself. Histo-cytochemical investigations and scanning electron microscopy showed that glandular trichome, after 4 h of HD, appeared swollen, with a deeply wrinkled surface and empty of essential oil, however maintaining the integrity of their cuticle. Many oil droplets were stuck to the outside of the trichome cuticle, sometimes arranged in large aggregates. After 20 min of MADH or MASD, trichomes appeared empty as well, but also particularly disrupted, or at least with holes in their head cuticle. Oil droplets were present outside the glands and in the inter-rib regions of the flower calyx, except in the case of MASD. After this extraction method, neither oil droplets nor other lipid staining were present in the samples, confirming the effectiveness of this particular MADH technique. These investigations suggest that the rapidity of MADH and MASD in extracting essential oil is mainly due to the collapse of trichome structure and the consequent direct release of its content, without which it has to slowly permeate through membranes and cuticle, as in the case of HD. Copyright © 2006 John Wiley & Sons, Ltd. [source] Modeling and simulation of polymeric nanocapsule formation by emulsion diffusion methodAICHE JOURNAL, Issue 8 2009M. Hassou Abstract The objective of this work is to develop a predictive dynamical model of a nanoencapsulation process using an emulsion diffusion method. This model describes the formation of the polymeric membrane around the oil droplet and its size reduction due to the solvent diffusion. To this end, we assume that the phase separation is only due to purely diffusive mechanism. This work is illustrated on the formation of poly-,-caprolactone (PCL) around the oily core formed of labrafac from the initial homogeneous polymer-solvent-nonsolvent solution (PCL, ethyl acetate, and labrafac). The polymeric membrane formation, the size reduction of the nanocapsule after the solvent diffusion, and the morphology of nanocapsules are experimentally investigated. It is shown that the results obtained in simulation from the dynamical model are in agreement with the experimental ones. The model is then used to predict the effect of the initial composition on the nanocapsule morphology. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Morphology, characterization, and distribution of retinal photoreceptors in the Australian lungfish Neoceratodus forsteri (Krefft, 1870)THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2006Helena J. Bailes Abstract The Australian lungfish Neoceratodus forsteri (Dipnoi) is an ancient fish that has a unique phylogenetic relationship among the basal Sarcopterygii. Here we examine the ultrastructure, histochemistry, and distribution of the retinal photoreceptors using a combination of light and electron microscopy in order to determine the characteristics of the photoreceptor layer in this living fossil. Similar proportions of rods (53%) and cones (47%) reveal that N. forsteri optimizes both scotopic and photopic sensitivity according to its visual demands. Scotopic sensitivity is optimized by a tapetum lucidum and extremely large rods (18.62 ± 2.68 ,m ellipsoid diameter). Photopic sensitivity is optimized with a theoretical spatial resolving power of 3.28 ± 0.66 cycles degree,1, which is based on the spacing of at least three different cone types: a red cone containing a red oil droplet, a yellow cone containing a yellow ellipsoidal pigment, and a colorless cone containing multiple clear oil droplets. Topographic analysis reveals a heterogeneous distribution of all photoreceptor types, with peak cone densities predominantly found in temporal retina (6,020 rods mm,2, 4,670 red cones mm,2, 900 yellow cones mm,2, and 320 colorless cones mm,2), but ontogenetic changes in distribution are revealed. Spatial resolving power and the diameter of all photoreceptor types (except yellow cones) increases linearly with growth. The presence of at least three morphological types of cones provides the potential for color vision, which could play a role in the clearer waters of its freshwater environment. J. Comp. Neurol. 494:381,397, 2006. © 2005 Wiley-Liss, Inc. [source] Application of toxicity identification evaluation procedures for characterizing produced water using the tropical mysid, Metamysidopsis insularisENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2004Najila Elias-Samlalsingh Abstract Toxicity identification evaluations (TIEs) were performed on seven produced water (PW) effluents from inland discharge facilities operated in Trinidad and Tobago, a Caribbean tropical country with one of the oldest commercial oil industries in the world. The research was performed to determine the presence and magnitude of toxicity and characterize which toxicants are responsible for observed effects. Marine effluent toxicity characterizations with Metamysidopsis insularis revealed high whole acute toxic-unit response for produced water ranged from 8.1 to >17.0 acute toxic-unit (initial toxicity test) and 5.7 to 1,111 acute toxic-unit (baseline toxicity test). Toxicity test results for all sites except one, which had the highest toxicity, are comparative with similar studies on produced water. The toxicological causality of this complex mixture differed for each PW with nonpolar organics being consistently toxic in all samples. Other potential toxicants contributing to overall toxicity to a much lesser extent were metals, ammonia, and volatile organic compounds. With the use of sodium thiosulfate and filtration manipulations for only PW6 sample, there was very slight reduction in toxicity; therefore, oxidants and filterable materials were not a great contributing factor. Whole effluent toxicity also can be attributed to ionic imbalance and the very stable oil-in-water emulsion that consists of fine oil droplets (less than 0.1,10 ,m with an average diameter of 2.5 ,m). This investigation is the first of its type in Trinidad and demonstrates clearly the applicability of this test method and local test species for evaluating complex effluents in tropical environments. [source] Histo-cytochemistry and scanning electron microscopy of lavender glandular trichomes following conventional and microwave-assisted hydrodistillation of essential oils: a comparative studyFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2006Marcello Iriti Abstract The conventional hydrodistillation method (HD) has been compared with three different variants of the microwave-assisted hydrodistillation technique (MADH), on Lavandula angustifolia flowers, both in terms of oil yield and effects on the glandular trichome morpho-structure. The amount and composition of essential oil extracted in 4 h by HD was similar to that obtained in only 20 min by MADH and even lower than that extracted with a steam variant (MASD) of MADH itself. Histo-cytochemical investigations and scanning electron microscopy showed that glandular trichome, after 4 h of HD, appeared swollen, with a deeply wrinkled surface and empty of essential oil, however maintaining the integrity of their cuticle. Many oil droplets were stuck to the outside of the trichome cuticle, sometimes arranged in large aggregates. After 20 min of MADH or MASD, trichomes appeared empty as well, but also particularly disrupted, or at least with holes in their head cuticle. Oil droplets were present outside the glands and in the inter-rib regions of the flower calyx, except in the case of MASD. After this extraction method, neither oil droplets nor other lipid staining were present in the samples, confirming the effectiveness of this particular MADH technique. These investigations suggest that the rapidity of MADH and MASD in extracting essential oil is mainly due to the collapse of trichome structure and the consequent direct release of its content, without which it has to slowly permeate through membranes and cuticle, as in the case of HD. Copyright © 2006 John Wiley & Sons, Ltd. [source] Superoleophobic Surfaces: Bioinspired Design of a Superoleophobic and Low Adhesive Water/Solid Interface (Adv. Mater.ADVANCED MATERIALS, Issue 6 20096/2009) The inside cover shows a bionic strategy to create a low-adhesive and superoleophobic interface via the oil/water/solid three-phase system, which was inspired by the antiwetting behavior of the oil droplets on the fish scales in water, as reported by Lei Jiang and co-workers on p.665. Such antiwetting behavior provides an insight into why many seabirds but few fish are killed when oil tanker spills occur. [source] Bioinspired Design of a Superoleophobic and Low Adhesive Water/Solid Interface,ADVANCED MATERIALS, Issue 6 2009Mingjie Liu The wetting/antiwetting behavior of liquid droplets on a solid surface is not an apparent or simple contact between two phases, but among three phases. Inspired by the antiwetting behavior of oil droplets on fish scales in water, a superoleophobic and low-adhesive interface is created on a solid substrate with micro/nanohierarchical structures, using oil/water/solid three-phase systems. [source] Snap-off of a liquid drop immersed in another liquid flowing through a constricted capillaryAICHE JOURNAL, Issue 8 2009T. J. Peña Abstract Emulsions are encountered at different stages of oil production processes, often impacting many aspects of oilfield operations. Emulsions may form as oil and water come in contact inside the reservoir rock, valves, pumps, and other equipments. Snap-off is a possible mechanism to explain emulsion formation in two-phase flow in porous media. Quartz capillary tubes with a constriction (pore neck) served to analyze snap-off of long ("infinite") oil droplets as a function of capillary number and oil-water viscosity ratio. The flow of large oil drops through the constriction and the drop break-up process were visualized using an optical microscope. Snap-off occurrence was mapped as a function of flow parameters. High oil viscosity suppresses the breakup process, whereas snap-up was always observed at low dispersed-phase viscosity. At moderate viscosity oil/water ratio, snap-off was observed only at low capillary number. Mechanistic explanations based on competing forces in the liquid phases were proposed. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Control of the morphology and the size of complex coacervate microcapsules during scale-upAICHE JOURNAL, Issue 6 2009C. Y. G. Lemetter Abstract Scale-up of complex coacervation, a fat encapsulation technology, is not trivial since the microcapsules morphology and size are highly affected by the processing conditions. So far it has been achieved empirically (trial and error approach). The goal of this study was to produce at various scale capsules with a single-oil droplet as the core material and small enough to be below sensory threshold. The turbulence level was identified as the main scale-up criterium and a master-curve could be drafted showing the capsule mean diameter as function of the Reynolds number, independent of the level of production scale. From a parent emulsion with specific oil droplets size (12,15 ,m), the Reynolds number had to be maintained above a critical value (15,000) to avoid capsules agglomeration with multiple oil cores and large particle sizes. To avoid aggregation, this turbulence level had to be kept until the temperature dropped below a critical value (14°C for a cooling rate of 35°C/2 h). Applying these learning led to a successful scale-up from bench (2 L) to a pilot plant scale of 50 L. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Effects of sand and process water pH on toluene diluted heavy oil in water emulsions in turbulent flowAICHE JOURNAL, Issue 1 2009Chandra W. Angle Abstract The presence of sand in heavy oil production is known to enhance oil recovery. Sand can also be detrimental depending on the properties of the sand,water interface. In this process, the water soluble material interacts with both sand and oil droplets and affects emulsion stability. The formation and stability of heavy oil-in-water emulsions during turbulent flow using batch process stirred-tank mixing of oil, sand, and water were investigated at three pH. Size distributions were measured by laser diffraction. High-speed video photomicrography was used to observe the process during mixing. Results showed that the presence of sand enhanced formation of stable, fine emulsion at basic pH 8.5. When the pH of the water was reduced below 6.5 both sand and droplets surface properties changed, the emulsions became less stable and coalescence was apparent. The sand grains acted as coalescers at low pH and enhanced breakage at high pH. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources, 2008 AIChE J, 2009 [source] Size distributions and stability of toluene diluted heavy oil emulsionsAICHE JOURNAL, Issue 3 2006Chandra W. Angle Abstract The sizes and stability of oil droplets created from various concentrations of heavy oil-in-toluene at a fixed oil:water ratio were investigated during turbulent flow in model process water. The Reynolds number (Re) ranged from 17,000 to 34,500 and was obtained by stirred tank mixing with a Rushton turbine. The droplet sizes were monitored using laser light scattering. Results showed that at high Re and low oil concentrations (that is, low drop-surface coverage), breakage of the droplets was the dominant process, but as Re was reduced, coalescence was dominant. Droplets were less prone to breakage as the oil concentrations in toluene increased, and droplet sizes approached a steady state quickly during mixing. Their size distributions broadened and stability increased as heavy oil in toluene increased. Stability was attributed to a surface coverage by asphaltenes and the consequent interfacial elasticity that provided resilience to breakage. Equilibrium interfacial tension ,E was determined by fitting a diffusion-limited kinetic mathematical model to the data. The Gibbs adsorption model gave a monolayer surface coverage of 3 nm2/mol asphaltenes, consistent with other published results. High zeta potential of the droplets also hindered coalescence. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] A review of the background, operating parameters and applications of microemulsion liquid chromatography (MELC)JOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2005A. Marsh Abstract Microemulsions are dispersions of nanometre-sized droplets of an immiscible liquid within another liquid. Droplet formation is facilitated by the addition of surfactants and often also cosurfactants. Microemulsions are classified as either oil-in-water (O/W) (oil droplets such as octane dispersed throughout aqueous buffer) or water-in-oil (W/O) (aqueous droplets in oil such as hexane). Both microemulsion types have been used as mobile phases for separation in microemulsion HPLC (MELC). There has been a recent increase of interest in this area with new applications and developments such as gradient elution and optimisation of methods using experimental design. O/W microemulsions have been employed as eluents for RP-HPLC while W/O microemulsions have been used for normal phase chromatography. Separations can have superior speed and efficiency to conventional HPLC modes while offering a unique selectivity with excellent resolution. The capability for quantitative and stability-indicating analysis has also been demonstrated. Specific advantages include the ability to operate at low UV wavelengths and elimination of the need for an equilibration rinse between gradients. Operational issues associated with the use of MELC have been identified including the need to add salt to the gradient eluent, relatively high back-pressures and increased need for equipment cleaning compared to conventional RP eluent. This report details the different microemulsion types and compositions used and their reported applications. The use of gradient and isocratic elution is described. The effects on separations of varying operating parameters such as temperature, oil type and concentration, surfactant type and concentration, sample solvent, column type, and organic solvent addition will be discussed and illustrated. [source] Emulsifying properties of gum kondagogu (Cochlospermum gossypium), a natural biopolymerJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2009Ganga Modi Naidu Vegi Abstract BACKGROUND: Natural polymers are widely used as emulsifying agents in the food and pharmaceutical industries because of their low cost, biocompatibility and non-toxic nature. In the present study, emulsifying properties of the novel natural biopolymer gum kondagogu (GKG) were investigated. GKG solutions of different concentrations (0.1,0.6% w/v) were prepared in water and emulsified with liquid paraffin oil (40% v/v) in a high-speed homogeniser. Flow properties of the emulsions were measured using a rheometer. Emulsion stability and droplet size distribution were determined by visual observation, photomicrography and laser-scattering particle size distribution analysis. RESULTS: The emulsions prepared with GKG showed pseudoplastic behaviour. The size of oil droplets and the viscosity of emulsions at concentrations of 0.4,0.6% w/v showed little change over time (up to 30 days), indicating that the emulsions were stable. Measurements of the zeta potential of emulsions adjusted to different pH, with and without added electrolyte, showed that the stabilisation of emulsions with GKG was due to mutual repulsion between electrical double layers of particles and adsorption of macromolecules on oil droplets. CONCLUSION: The results of this experimental investigation show that GKG is a good emulsifying agent even at low concentrations, with many potential applications in the food and pharmaceutical industries. Copyright © 2009 Society of Chemical Industry [source] Emulsifying properties of gelatin conjugated to pectin under alkaline conditionsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2005Nickolaos G Diftis Abstract Gelatin,pectin mixed solution incubated under mild alkaline conditions for a period of 4 h exhibited an improvement of emulsion stability in terms of both droplet coalescence and serum separation. Application of SDS,PAGE provided evidence for gelatin,pectin hybrid formation possibly due to amide bonds between the lysine group residues of protein and the esterified carboxyl groups of the polysaccharide. The superior stabilizing properties of the heat-treated protein,polysaccharide conjugate is attributed to the enhancement of the repulsive steric forces operating between emulsion oil droplets, as a result of conjugate adsorption through their protein moiety. Copyright © 2004 Society of Chemical Industry [source] The complexity of the visual cells and visual pathways of the sturgeonMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2004Marong Fang Abstract The visual cells in the retinae of the sturgeon were studied by scanning electron microscopy and transmission electron microscopy. Our investigations revealed the presence of rods, two types of single cones, one type of double cone (two nonidentical cone components adhered together), and one type of twin cone (two identical cone components adhered together). In some of the cones, large glycogen bodies were present in the inner segments and all cones contained oil droplets. Such cone morphology was very similar to that described in the retinae of higher vertebrates, for example the chicken. DiI tracing of retinofugal pathways following uniocular injection demonstrated their bilateral localization and extensive termination in the diencephalon and mesencephalon of both sides. Fibers also crossed over from one side to another through commissures, including the posterior commissure. The complexity of the pathway surpassed that of the teleosts and further indicated the evolutionary importance of this fish. Microsc. Res. Tech. 65:122,129, 2004. © 2004 Wiley-Liss, Inc. [source] Development of a new high-efficiency simple structure cycloneTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Z. Tan Abstract A novel uniflow cyclone design was evaluated using three prototype cyclones. For the first two, the efficiency and Euler number were determined using airborne solid particles with a number mean diameter of 12.5 µm. Then a larger scale prototype based on the optimized geometry was compared with an existing conventional high efficiency cyclone and a vane-induced uniflow cyclone, using mineral oil droplets with a number mean diameter of 8.9 µm. Both sets of experiments showed that the newly designed cyclone had a higher efficiency at a higher pressure requirement, in addition to the feature of a small footprint. Un nouveau modèle de cyclone uniflow a été évalué à l'aide de trois cyclones prototypes. Pour les deux premiers cyclones, l'efficacité et la perte de charge ont été déterminées avec des particules solides transportées par le gaz de diamètre moyen en nombre de 12,5 micromètres. Puis un prototype à plus grande échelle basé sur la géométrie optimisée a été comparé à un cyclone conventionnel existant à haute efficacité et à un cyclone uniflow à ailettes, en utilisant des gouttelettes d'huile minérale d'un diamètre moyen en nombre de 8,9 micromètres. Les deux séries d'expériences montrent que le nouveau modèle de cyclone a une plus grande efficacité ou une demande de pression moins grande, en plus d'être plus compact. [source] Morphology, characterization, and distribution of retinal photoreceptors in the Australian lungfish Neoceratodus forsteri (Krefft, 1870)THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2006Helena J. Bailes Abstract The Australian lungfish Neoceratodus forsteri (Dipnoi) is an ancient fish that has a unique phylogenetic relationship among the basal Sarcopterygii. Here we examine the ultrastructure, histochemistry, and distribution of the retinal photoreceptors using a combination of light and electron microscopy in order to determine the characteristics of the photoreceptor layer in this living fossil. Similar proportions of rods (53%) and cones (47%) reveal that N. forsteri optimizes both scotopic and photopic sensitivity according to its visual demands. Scotopic sensitivity is optimized by a tapetum lucidum and extremely large rods (18.62 ± 2.68 ,m ellipsoid diameter). Photopic sensitivity is optimized with a theoretical spatial resolving power of 3.28 ± 0.66 cycles degree,1, which is based on the spacing of at least three different cone types: a red cone containing a red oil droplet, a yellow cone containing a yellow ellipsoidal pigment, and a colorless cone containing multiple clear oil droplets. Topographic analysis reveals a heterogeneous distribution of all photoreceptor types, with peak cone densities predominantly found in temporal retina (6,020 rods mm,2, 4,670 red cones mm,2, 900 yellow cones mm,2, and 320 colorless cones mm,2), but ontogenetic changes in distribution are revealed. Spatial resolving power and the diameter of all photoreceptor types (except yellow cones) increases linearly with growth. The presence of at least three morphological types of cones provides the potential for color vision, which could play a role in the clearer waters of its freshwater environment. J. Comp. Neurol. 494:381,397, 2006. © 2005 Wiley-Liss, Inc. [source] Early ontogeny of the spotted wolffish (Anarhichas minor Olafsen)AQUACULTURE RESEARCH, Issue 12 2003Inger-Britt Falk-Petersen Abstract This study illustrates the embryo development of the spotted wolffish (Anarhichas minor Olafsen), an interesting candidate for cold-water aquaculture. The egg morphology (semitransparent, yellow-white with numerous oil droplets in the yolk), size (5.4,6.5 mm) and long embryogenesis (c. 800,1000 d°, depending on temperature) of A. minor are very similar to Anarhichas lupus. Cleavage is slow, and the first cell divisions take place at 12 h at 8°C. After 12 days the 2-mm embryo with the first somites is laid down and the blastopore starts closing. The fat globules in the yolk fuse into one after 22 days, and after 30 days eye pigmentation is noticeable. After 44 days, eye pigmentation is strong, the digestive tract folded and a green gall bladder can be noted in the now 11-mm-long embryo. One week later the blood is brightly red, the intestine is pigmented and the lower jaw is well developed. Premature hatching may occur from this stage. After 58 days vascularization of the yolk is complete, capillaries are noted in the fin fold, the first ray rudiments are established in the tail and pectoral fins, and the four gill arches are covered by the operculum. The preanal finfold is reduced after 72 days, stomach and gill filaments are formed, and six pigmented rows are noted on the 17-mm-long embryo body. After 86 days all fin rays are seen and the digestive tract is intensely pigmented and folded. Hatching (normal) starts after 110 days and may last for 2,3 weeks. Late embryos and early larvae of A. minor have more distinct bands of pigment along the body compared with the closely related A. lupus. An increase in both length and weight of the embryos in individual batches occurs during the hatching period. [source] Enhancement of oil droplet removal from o/w emulsion by adding methylated milk casein in flotation techniqueASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Hideo Maruyama Abstract To clarify oil-in-water (o/w) emulsion, flotation experiments were conducted by adding methylated milk casein (MeCS), which is a biodegradable flocculant. Emulsion used in this study was prepared by ultrasonic emulsification of heavy oil (bunker-A) and sodium dodecyl sulfate (SDS) solution. It was found that addition of MeCS enhanced clarification of oil droplets from o/w emulsion solution due to floc formation by adding MeCS. An optimum dosage of MeCS to form effective floc was determined by the relative turbidity in a clarification experiment. In flotation experiments, clarification ability was evaluated by removal rate constant, k, obtained by fitting of turbidity data to a pseudo-first-order kinetic equation. In case of varying dosage of MeCS and keeping superficial gas velocity, Ug, at constant value (5.48 × 10,2 cm/s), removal rate was greatly influenced by amount of MeCS dosage. The maximum value of k was also obtained at the most optimum dosage of MeCS, and k decreased with adding lesser or larger amount of MeCS than the optimum dosage. On the other hand, in case of keeping the dosage of MeCS at the optimum dosage, and varying superficial gas velocity, up to Ug < ca. 0.2 cm/s, k was increased with increasing superficial gas velocity, and increase in removal rate of oil droplets was mostly proportional with increase in bubble surface area production rate. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Intravitreal silicone oil droplets following pegaptanib injectionACTA OPHTHALMOLOGICA, Issue 2 2010Mehmet Selim Kocabora No abstract is available for this article. [source] | ||||||||||||||||