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Droplet Size (droplet + size)
Terms modified by Droplet Size Selected AbstractsA Blind Trial Evaluation of a Crime Scene Methodology for Deducing Impact Velocity and Droplet Size from Circular Bloodstains,JOURNAL OF FORENSIC SCIENCES, Issue 1 2007Lee Hulse-Smith M.S. ABSTRACT: In a previous study, mechanical engineering models were utilized to deduce impact velocity and droplet volume of circular bloodstains by measuring stain diameter and counting spines radiating from their outer edge. A blind trial study was subsequently undertaken to evaluate the accuracy of this technique, using an applied, crime scene methodology. Calculations from bloodstains produced on paper, drywall, and wood were used to derive surface-specific equations to predict 39 unknown mock crime scene bloodstains created over a range of impact velocities (2.2,5.7 m/sec) and droplet volumes (12,45 ,L). Strong correlations were found between expected and observed results, with correlation coefficients ranging between 0.83 and 0.99. The 95% confidence limit associated with predictions of impact velocity and droplet volume was calculated for paper (0.28 m/sec, 1.7 ,L), drywall (0.37 m/sec, 1.7 ,L), and wood (0.65 m/sec, 5.2 ,L). [source] Investigation of a New Approach to Measuring Contact Angles for Hydrophilic Impression MaterialsJOURNAL OF PROSTHODONTICS, Issue 2 2007Gerard Kugel DMD Purpose: The purpose of this investigation was to examine the initial water contact angles of seven unset impression materials using commercially available equipment, in an effort to determine whether polyether impression materials (Impregum) have lower contact angles and are, therefore, more hydrophilic than VPS impression materials. Materials and Methods: The hydrophilic properties of unset polyether and VPS impression materials were analyzed with respect to their water contact angle measurements using the commercially available Drop Shape Analysis System DSA 10. Twenty-five data points per second were collected via video analysis. There was no delay from start of measurement and data collection. Data was collected for approximately 12 s. Droplet size was determined on the thickness of canula. If the droplets became too small in volume, the water that evaporated during the measurement was large in comparison to the volume of the droplet. Therefore, 5 ,l was chosen as the lowest volume. Five trials were conducted per series for each featured material. Contact angles were calculated using the circle fitting method. Three tests using this technique were designed to control the variables of contact angle measurement with regard to time, the varying amount of fluid in contact with impression material during clinical use, and material thickness. Sample thickness of impression material was controlled by stripping the paste flat on a glass plate using a marking template to ensure a constant film thickness. Tests were conducted in a climatized room at 24°C ± 1°C. Deionized water was used as the fluid. The device was calibrated according to manufacturer's instruction for Young,Laplace fitting prior to the measurements. Results were analyzed using One-Way ANOVA, Tukey test, and t -test, as appropriate. Results: Comparing the fast setting impression materials by One-Way ANOVA and Tukey tests (p < .05) revealed the initial contact angles to range from 66.2 ± 1.5° to 127.5 ± 4.4°, of which the polyether material was the lowest after 45 s (66.2 ± 1.5°), 120 s (70.3 ± 2.8°), and 24 h (80.3 ± 1.0°) after start of the mix. The selected times represent the different stages of unset material, ranging from 45 s as the earliest practical data collection time to 24 h, at which a stone model would be poured. The polyether materials tested exhibited lower contact angles and, thus, significantly higher initial hydrophilicity than all measured VPS materials. Additionally, Impregum impression materials are more hydrophilic in the unset stage than in the set stage. VPS may show a stepwise development of hydrophilicity in the set stage that was not observed in the unset stage. Conclusions: The polyether impression materials tested were significantly more hydrophilic before, during, and after setting than that of VPS impression materials. Regardless of the amount of water in contact with the impression material, the polyether impression materials showed a significantly higher hydrophilicity in the unset stage than the VPS materials. The initial contact angle was not dependent on the thickness of the material. All parameters, including variation of time, volume of water droplet, and thickness of material, resulted in different absolute contact angles, but did not lead to a dramatic change in the ranking of the materials with regard to their hydrophilic behavior. [source] Effect of Ultra-high-pressure Homogenization on Structure and on Rheological Properties of Soy Protein-stabilized EmulsionsJOURNAL OF FOOD SCIENCE, Issue 9 2002J. Floury ABSTRACT: An ultra high-pressure homogenizer (20 to 350 MPa) was used to realize fine food emulsions stabilized by soy proteins. The first aim of the work was to understand how dynamic high-pressure processing affects soybean globulin conformation. Then, the effect of homogenizing pressure on the emulsions structure and rheology was investigated. High-pressure homogenization caused denaturation of proteins due to strong mechanical forces and high temperatures encountered in the valve. Droplet sizes of emulsions were greatly reduced with high-pressure homogenization and Newtonian liquid emulsions were converted into shear-thinning emulsion gels by homogenization at pressures above 250 MPa. Hydrophobic interactions between proteins were supposed to cause the gel-like network structure of emulsions. [source] An investigation of human brain tumour lipids by high-resolution magic angle spinning 1H MRS and histological analysisNMR IN BIOMEDICINE, Issue 7 2008Kirstie S. Opstad Abstract NMR-visible lipid signals detected in vivo by 1H MRS are associated with tumour aggression and believed to arise from cytoplasmic lipid droplets. High-resolution magic angle spinning (HRMAS) 1H MRS and Nile Red staining were performed on human brain tumour biopsy specimens to investigate how NMR-visible lipid signals relate to viable cells and levels of necrosis across different grades of glioma. Presaturation spectra were acquired from 24 adult human astrocytoma biopsy samples of grades II (8), III (2) and IV (14) using HRMAS 1H MRS and quantified using LCModel to determine lipid concentrations. Each biopsy sample was then refrozen, cryostat sectioned, and stained with Nile Red, to determine the number of lipid droplets and droplet size distribution, and with Haematoxylin and Eosin, to determine cell density and percentage necrosis. A strong correlation (R,=,0.92, P,<,0.0001) was found between the number of Nile Red-stained droplets and the ,1.3,ppm lipid proton concentration by 1H MRS. Droplet sizes ranged from 1 to 10,µm in diameter, and the size distribution was constant independent of tumour grade. In the non-necrotic biopsy samples, the number of lipid droplets correlated with cell density, whereas in the necrotic samples, there were greater numbers of droplets that showed a positive correlation with percentage necrosis. The correlation between 1H MRS lipid signals and number of Nile Red-stained droplets, and the presence of lipid droplets in the non-necrotic biopsy specimens provide good evidence that the in vivo NMR-visible lipid signals are cytoplasmic in origin and that formation of lipid droplets precedes necrosis. Copyright © 2008 John Wiley & Sons, Ltd. [source] Assessment of fire protection performance of water mist applied in exhaust ducts for semiconductor fabrication processFIRE AND MATERIALS, Issue 5 2005Yi-Liang Shu Abstract Fume exhaust pipes used in semiconductor facilities underwent a series of fire tests to evaluate the performance of a water mist system. The parameters considered were the amount of water that the mist nozzles used, the air flow velocity, the fire intensity and the water mist system operating pressure. In order to make a performance comparison, tests were also performed with a standard sprinkler system. The base case served as a reference and applied a single water mist nozzle (100 bar operating pressure, 7.3 l/min water volume flux and 200 µm mean droplet size) installed in the pipe (60 cm in diameter) subjected to a 350°C air flow with an average velocity of 2 m/s. In such a case, the temperature in the hot flow dropped sharply as the water mist nozzle was activated and reached a 60°C saturation point. Under the same operating conditions, four mist nozzles were applied, and made no further contribution to reducing the fire temperature compared with the case using only a single nozzle. Similar fire protection performances to that in the base case were still retained when the exhaust flow velocity increased to 3 m/s and the inlet air temperature was increased to 500°C due to a stronger input fire scenario, respectively. Changing to a water mist system produced a better performance than a standard sprinkler. With regard to the effect of operating pressure of water mist system, a higher operating pressure can have a better performance. The results above indicate that the droplet size in a water-related fire protection system plays a critical role. Copyright © 2005 John Wiley & Sons, Ltd. [source] Skin moisturization by hydrogenated polyisobutene,Quantitative and visual evaluationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2010N. Dayan J. Cosmet. Sci., 60, 15,24 (January/February 2009) Synopsis Hydrogenated polyisobutene (HP) is used in topically applied cosmetic/personal care formulations as an emollient that leaves a pleasing skin feel when applied, and rubbed in after application. This effect, although distinguishable to the user, is difficult to define and quantify. Recognizing that some of the physical properties of HP such as film formation and wear resistance may contribute, in certain mechanisms, to skin moisturization, we designed a short-term pilot study to follow changes in skin moisturization. HP's incorporation into an o/w emulsion at 8% yielded increased viscosity and reduced emulsion droplet size as compared to the emollient ester CCT (capric/caprylic triglyceride) or a control formulation. Quantitative data indicate that application of the o/w emulsion formulation containing either HP or CCT significantly elevated skin moisture content and thus reduced transepidermal water loss (TEWL) by a maximal ,33% against the control formulation within 3 h and maintained this up to 6 h. Visual observation of skin treated with the HP-containing formulation showed fine texture and clear contrast as compared to the control or the CCT formulation, confirming this effect. As a result of increased hydration, skin conductivity, as measured in terms of corneometer values, was also elevated significantly by about tenfold as early as 20 min after HP or CCT application and was maintained throughout the test period. Throughout the test period the HP formulation was 5,10% more effective than the CCT formulation both in reduction of TEWL as well as in increased skin conductivity. Thus, compared to the emollient ester (CCT), HP showed a unique capability for long-lasting effect in retaining moisture and improving skin texture. [source] The characterization of the semi-solid W/O/W emulsions with low concentrations of the primary polymeric emulsifierINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2005D. Vasiljevic Synopsis Semi-solid multiple W/O/W emulsions with low concentrations (0.8, 1.6 and 2.4% w/w) of lipophilic polymeric primary emulsifier PEG-30-dipolyhydroxystearate (PDHS) have been formulated. Both emulsions, primary and multiple, were prepared with high content of inner phase (,1 = ,2 = 0.8). All the formulations differ only in the lipophilic emulsifier concentration. Evaluating several parameters such as macroscopic and microscopic aspect, droplet size, accelerated stability under centrifugation and flow and oscillatory rheological behaviour, assessed the multiple systems. It is possible to formulate the semi-solid W/O/W multiple emulsions with low concentrations of PDHS as the primary emulsifier. It appeared that the highest long-term stable multiple emulsion with the lowest droplet size, the highest apparent viscosity and highest elastic characteristic, was the sample with the highest concentration (2.4% w/w) of the primary emulsifier. Résumé Les émulsions H/L/H semi-solides ont été formulées avec les concentrations basses (0.8, 1.6 et 2.4% m/m) de l'émulsifiant lipophile polymèrique PEG-30-dipolyhydroxystearate. Les émulsions simples et multiples ont été préparées avec la teneur élevée en phase intérieure (,1 = ,2 = 0.8). La teneur en émulsifiant lipophile était la seule différence entre ces formulations. L'aspect macroscopique et microscopique, la taille de globules, la stabilité physique déterminée par le test de centrifugation ainsi que le comportement rhéologique (rhéologie d'écoulement et oscillatoire) ont permis l'évaluation des émulsions multiples. Il est possible de formuler les émulsions H/L/H semi-solides multiples avec les concentrations basses de PEG-30-dipolyhydroxystearate comme émulsifiant primaire. Il a été découvert que l'émulsion H/L/H multiple avec le plus grand pourcentage (2.4% m/m) de l'émulsifiant primaire a le diamètre de globule le plus petit, la plus grande viscosité apparente et le plus grand module élastique ainsi que la plus longue stabilité. [source] The rheological behaviour of low fat soy-based salad dressingINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2008Chi Zhang Summary Low fat soy-based salad dressings were formulated with different oil levels (3%, 13% and 23%) and emulsifiers (whey protein concentrate, soy-lecithin and sodium caseinate) using either blender or ultra-turrax (UT) homogeniser. Results showed that the rheological behaviour of these samples were highly dependent on the oil content, emulsifiers and blending methods. The UT method produced samples with better viscosity and have droplet size of 2,100 ,m. Samples containing higher oil level have higher viscosity, smaller droplet size, larger G, and G, values. All samples show a shear-thinning effect and larger G, than G,, indicating the elastic nature of the samples. A quantity Q(t)% was applied to estimate the elasticity and the values were found to be in the range 22.8,85.2%. G, and G, were found to decrease with increased temperature. However, tan , increased slightly with temperature; the values ranged from 0.2 to 0.4 at 5 °C to 0.3,0.5 at 25 °C. Current results demonstrated that the formulated samples have good stability compared with commercial products. [source] EFFECT OF FLAXSEED GUM ON QUALITY AND STABILITY OF A MODEL SALAD DRESSING,JOURNAL OF FOOD QUALITY, Issue 4 2000S. STEWART ABSTRACT Flaxseed gum was evaluated for its application as a stabilizer for salad dressing. It was found that for stabilization to occur the concentration of gum had to be higher than 0.45% (w/w). Solvent quality affected the stability of model oil-in-water emulsions. Flaxseed gum stabilized emulsions were stable at pHs greater than 2.8. Lower values caused the polysaccharide to have a compact configuration or caused cleavage of the polymer creating instability. Larger mean droplet size and creaming were observed when the pH was too low or the gum concentration was not sufficient for coverage. Salt addition greatly affected the rheological properties of the polysaccharide; however, the electrolyte improved the emulsifying capabilities of the egg yolk protein. Aging weakened the polymer network structure as shown by a decrease in Newtonian viscosity with a corresponding increase in phase angle confirming the transformation to a more fluid system. [source] A descriptive force-balance model for droplet formation at microfluidic Y-junctionsAICHE JOURNAL, Issue 10 2010Maartje L. J. Steegmans Abstract In a previous article, we studied the basics of emulsification in microfluidic Y-junctions, however, without considering the effect of viscosity of the disperse phase. As it is known from investigations on many different microstructures that viscosity and viscosity ratio are governing parameters for droplet size, we here investigate whether this is also the case for microfluidic Y-junctions and do so for a wide range of process conditions. The investigated Y-junctions have a width of 19.9 or 12.8 ,m and a depth of 5.0 ,m, and the formed monodisperse droplets (CV < 1%) are between 3 and 20 ,m. We varied the disperse-phase viscosity using different oils (1,105 mPa s), and continuous-phase viscosity using glycerol,water and ethanol,water mixtures (1.0,6.2 mPa s), which corresponds to disperse-to-continuous-phase viscosity ratios from 0.4 to 105.0. Through the variation of the liquids, also a range in interfacial tensions (12,55 mN m,1) is assessed. The disperse-phase flow rate is varied from 0.039 to 18.0 ,L h,1, the continuous-phase flow rate from 1.39 ,L h,1 to 0.41 mL h,1, and this corresponds to flow rate ratios from 1.1 × 10,3 to 0.14, which is once again based on wide range of conditions. For all these conditions, in which droplets are formed in the dripping and jetting regime, the droplet size could be described with a model based on the existing force-balance model, but now extended to incorporate the cross-sectional area of the droplet and the resistance with the wall. Surprisingly enough, it was found that the droplet size is not influenced by the disperse-phase viscosity, or the viscosity ratio, but it is dominated by the resistance with the wall and the continuous-phase properties. Because of this, emulsification with Y-junctions is intrinsically simpler than any other shear-based method as droplet size is only determined by the continuous phase. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Liquid,liquid two-phase flow in pore array microstructured devices for scaling-up of nanoparticle preparationAICHE JOURNAL, Issue 12 2009Shaowei Li Abstract Nanoparticles have been produced by a T-junction microchannel device in our previous work (Li et al., Langmuir. 2008;24:4194-4199). As a scaling-up strategy, pore array microstructured devices were designed to prepare nanoparticles in this article. H2SO4 and BaCl2, respectively, in two phases to form BaSO4 nanoparticles was used as a test system. The characteristics of a well controlled liquid,liquid two-phase flow in the pore array microstructured devices were presented. Nanoparticles with small size and good dispersibility were produced through drop or disk flows in the microstructured devices. The influence of mass transfer and chemical reaction on interfacial tension and flow patterns was discussed based on the experiments. Meanwhile, the effect of the two phase flow patterns on the nanoparticle size was discussed. It was found that the increase of the amount of mass transfer and chemical reaction could change the flow patterns from disk flow to drop flow. The droplet diameter could be changed in a wide range. Flow patterns could be distinguished based on the measured interfacial tension in different concentrations. The prepared nanoparticles were ranged from 10 nm to 30 nm. Apparently the particle size was decreased with the increase of the droplet size in both the drop flow region and the disk flow region whereas it had a reverse trend in the transition region. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Characterization of dynamical emulsification process in concentrated conditionsAICHE JOURNAL, Issue 8 2007Christophe Baravian Abstract Emulsification at constant shear rate in concentrated conditions (50% in volume fraction) is investigated experimentally by measuring simultaneously the droplet size and the global shear stress using a specially designed rheo-optical "Steady Light Transport" apparatus. The capillary number is varied by changing the continuous phase viscosity, corresponding to disperse to continuous phase viscosity ratios between 0.02 and 2. We show that when the capillary number is large enough (>0.35), emulsification occurs. At constant shear rate, this time-dependant process can be separated into four steps: (1) flow start-up, (2) premix formation, (3) a progressive reduction in droplet size, associated with an increase in shear stress, (4) changes in droplet size and shear stress stop at a well-defined emulsification time. Step (3), called dynamical emulsification, is fully controlled by the critical capillary number and the mechanism of drop size reduction stops when viscous dissipation dominates the droplet elongation and break-up mechanism. This approach accurately describes both the variation in shear stress with droplet size during Stage (3) and the final state of the emulsion in terms of droplet size and viscosity. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] Core,shell structure and segregation effects in composite droplet polymer blendsAICHE JOURNAL, Issue 4 2003Joël Reignier Core,shell morphology formation within the dispersed phase was studied for composite droplet polymer-blend systems comprising a high-density polyethylene matrix, polystyrene shell and different molecular weights of poly(methyl methacrylate) core material. The blends were prepared in the melt using an internal mixer, and the morphology was analyzed by electron microscopy. Changing the viscoelastic properties of the core in the dispersed phase dramatically affects PS-PMMA segregation within the dispersed composite droplet itself. A high-molecular-weight-PMMA core contains a large quantity of occluded PS inclusions, while the low-molecular-weight PMMA results in a perfectly segregated PS shell and PMMA core. These phenomena were attributed to the viscosity of the PMMA. Using the latter system, a direct microscopic study of the shell formation process demonstrates unambiguously that under conditions of perfect segregation, the onset of complete shell formation corresponds to a shell thickness that is close to two times the radius of gyration of polystyrene. Thus, the thinnest possible shell in such a system possesses a molecular-scale thickness. The system with the high-molecular-weight-PMMA core demonstrates an onset of complete shell formation that is displaced to higher concentrations due to the poor segregation effect. By counterbalancing the effects of viscosity ratio and interfacial effects on the composite droplet size, it is possible to generate perfectly segregated core,shell dispersed-phase morphologies of almost identical size with a controlled shell thickness ranging from 40 to 300 nm. [source] Calixarene-entrapped nanoemulsion for uranium extraction from contaminated solutionsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2010Aurélie Spagnul Abstract Accidental cutaneous contamination by actinides such as uranium occurring to nuclear power plant workers can lead to their dissemination in other tissues and induce severe damages. Until now, no specific emergency treatment for such contamination has been developed. The aim of the present work was to formulate a tricarboxylic calix[6]arene molecule, known to exhibit good affinity and selectivity for complexing uranium, within a topical delivery system for the treatment of skin contamination. Since calixarene was shown to reduce oil/water interfacial tension, we have designed an oil-in-water nanoemulsion, taking advantage of the small droplet size offering a high contact surface with the contaminated aqueous medium. Characterization of the calixarene nanoemulsion was performed by determination of the oily droplet size, zeta potential and pH, measured as a function of the calixarene concentration. The obtained results have confirmed the surface localization of calixarene molecules being potentially available to extract uranyl ions from an aqueous contaminated solution. In a preliminary experiments, the calixarene nanoemulsion was used for the removal of free uranium from an aqueous contaminated solution. Results showed that the calixarene nanoemulsion extracted up to 80,±,5% of uranium, which demonstrates the potential interest of this delivery system for uranium skin decontamination. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1375,1383, 2010 [source] Extractive bioconversion in a four-phase external-loop airlift bioreactorAICHE JOURNAL, Issue 7 2000Lidija Sajc The integration of biosynthesis and product separation can increase the productivity of immobilized plant cells in airlift bioreactors. Extractive bioconversion of anthraquinones was studied in an external-loop airlift bioreactor consisting of a riser, a downcomer, and two horizontal sections, while containing alginate-immobilized Frangula alnus cells, a continuous aqueous phase (nutrient solution), dispersed solvent phase (n-hexadecane or silicone oil), and gas bubbles. A simple mathematical model was developed to describe the cocurrent liquid-liquid extraction in the riser section of the bioreactor and to rationalize the measured product concentrations in the aqueous and solvent phase. The model equations were solved analytically in a dimensionless form and used to study the effects of flow conditions, solvent properties, product formation rate, droplet size, and contactor length on the extraction efficiency and product concentration profiles in the continuous and dispersed phase. [source] Cytotoxicity and apoptosis enhancement in brain tumor cells upon coadministration of paclitaxel and ceramide in nanoemulsion formulationsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2008Ankita Desai Abstract The objective of this study was to examine augmentation of therapeutic activity in human glioblastoma cells with combination of paclitaxel (PTX) and the apoptotic signaling molecule, C6 -ceramide (CER), when administered in novel oil-in-water nanoemulsions. The nanoemulsions were formulated with pine-nut oil, which has high concentrations of essential polyunsaturated fatty acid (PUFA). Drug-containing nanoemulsions were characterized for particle size, surface charge, and the particle morphology was examined with transmission electron microscopy (TEM). Epi-fluorescent microscopy was used to analyze nanoemulsion-encapsulated rhodamine-labeled PTX and NBD-labeled CER uptake and distribution in U-118 human glioblastoma cells. Cell viability was assessed with the MTS (formazan) assay, while apoptotic activity of PTX and CER was evaluated with caspase-3/7 activation and flow cytometry. Nanoemulsion formulations with the oil droplet size of approximately 200 nm in diameter were prepared with PTX, CER, and combination of the two agents. When administered to U-118 cells, significant enhancement in cytotoxicity was observed with combination of PTX and CER as compared to administration of individual agents. The increase in cytotoxicity correlated with enhancement in apoptotic activity in cells treated with combination of PTX and CER. The results of these studies show that oil-in-water nanoemulsions can be designed with combination therapy for enhancement of cytotoxic effect in brain tumor cells. In addition, PTX and CER can be used together to augment therapeutic activity, especially in aggressive tumor models such as glioblastoma. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:2745,2756, 2008 [source] IPM/DOSS/water microemulsions as reactors for silver sulfadiazine nanocrystal synthesisJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2005Jerry Nesamony Abstract The first goal of this work was the preparation of a water-in-oil microemulsion from components generally regarded as safe for use in humans. Stable formulations without need of a co-surfactant were prepared from isopropyl myristate (IPM), dioctyl sodium sulfosuccinate (DOSS), and water. A ternary phase diagram was prepared for the IPM/DOSS/water system. The IPM/DOSS/water microemulsions were characterized by conductivity and dynamic laser light scattering (DLS). The results obtained from conductivity experiments indicate conductivity values of less than 1 ,S/cm and were consistent with the formation of w/o microemulsions. The DLS results showed that the emulsified water droplets had an average diameter range of 9.2 to 19.7 nm, depending on composition. Modulation of the droplet size is possible by varying the water to DOSS molar ratio and DOSS to IPM ratio. The second goal of this work was the preparation of silver sulfadiazine (AgSD) nanoparticles. It was hypothesized that two separate microemulsions containing dispersed aqueous droplets of either sodium sulfadiazine or silver nitrate would react when mixed. The DLS results are consistent with the successful formation of submicron AgSD crystals. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1310,1320, 2005 [source] Developing a hybrid emulsion polymerization system to synthesize Fe3O4/polystyrene latexes with narrow size distribution and high magnetite contentJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2007Longlan Cui Abstract A hybrid emulsion polymerization was formulated for synthesizing Fe3O4/polystyrene composite latex. This system, containing binary droplets that are magnetic (Mag)-droplets with a diameter of 100,200 nm and styrene (St)-droplets with a diameter of 3,4 ,m, was obtained by mixing Mag-miniemulsion and St-macroemulsion. With extremely low surfactants concentration (,critical micelle concentration, CMC), the nucleated loci are selectively controlled in the Mag-droplets, as the result of smaller droplet size and larger surface ratio. Both water-soluble potassium persulfate (KPS) and oil-soluble 2,2,-azobis(2-isobutyronitrile) was adopted to initiate the polymerization. In the presence of KPS, magnetic polystyrene latices with particles size of 60,200 nm, narrow size distribution, and high magnetite content (86 wt % measured by TGA) were attained successfully. The synthesized magnetic Fe3O4/polystyrene latices assembled into well-ordered hexagonal structure in the surface of a carbon supported copper grid. The influence of various parameters on various aspects of the as-synthesized Fe3O4/polystyrene was investigated in detail: type of initiator on composite morphology, feed ratio of Mag-miniemulsion and St-macroemulsion on magnetite content, and hydrophobic agent or amount of surfactant on size and size distribution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5285,5295, 2007 [source] Model salad dressing emulsion stability as affected by the type of the lupin seed protein isolateJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2006Evdoxia Papalamprou Abstract Model salad dressing emulsions of an oil volume fraction of 0.50 were prepared using two types of lupin seed protein isolate (LSPI) differing in the method applied for their isolation and their protein composition. The dressing stability against creaming and droplet coalescence were studied and correlated with data on oil droplet size, rheological characteristics and the amount of protein adsorption at the droplet surfaces. Model salad dressing emulsions containing the isolate, mainly composed of lupin globulins, exhibited higher stability and more pronounced rheological characteristics compared to those prepared with the isolate enriched in albumins or with the mixture of the two isolates. The lupin albumins appeared to displace the globulins from the droplet surfaces, following competitive adsorption from mixtures of the two types of the lupin isolates. The results are discussed in terms of droplet interaction and rearrangement as they are influenced by the presence of the adsorbed protein molecules and aggregates which appear to determine long-term stability of the emulsion systems. Copyright © 2006 Society of Chemical Industry [source] Cryogen spray cooling: Effects of droplet size and spray density on heat removalLASERS IN SURGERY AND MEDICINE, Issue 2 2001Brian M. Pikkula BS Abstract Background and Objective Cryogen spray cooling (CSC) is an effective method to reduce or eliminate non-specific injury to the epidermis during laser treatment of various dermatological disorders. In previous CSC investigations, fuel injectors have been used to deliver the cryogen onto the skin surface. The objective of this study was to examine cryogen atomization and heat removal characteristics of various cryogen delivery devices. Study Design/Materials and Methods Various cryogen delivery device types including fuel injectors, atomizers, and a device currently used in clinical settings were investigated. Cryogen mass was measured at the delivery device output orifice. Cryogen droplet size profiling for various cryogen delivery devices was estimated by optically imaging the droplets in flight. Heat removal for various cryogen delivery devices was estimated over a range of spraying distances by temperature measurements in an skin phantom used in conjunction with an inverse heat conduction model. Results A substantial range of mass outputs were measured for the cryogen delivery devices while heat removal varied by less than a factor of two. Droplet profiling demonstrated differences in droplet size and spray density. Conclusions Results of this study show that variation in heat removal by different cryogen delivery devices is modest despite the relatively large difference in cryogen mass output and droplet size. A non-linear relationship between heat removal by various devices and droplet size and spray density was observed. Lasers Surg. Med. 28:103,112, 2001. © 2001 Wiley-Liss, Inc. [source] Polymerisable Miniemulsions Using Rotor-Stator HomogenisersMACROMOLECULAR REACTION ENGINEERING, Issue 4 2008Ula El-Jaby Abstract The use of a rotor-stator mixer as a homogenisation device to make miniemulsion droplets with industrially pertinent solid contents was investigated. Methyl methacrylate/butyl acrylate (50:50 w/w ratio) miniemulsions with droplet diameters from 2 µm to 300 nm and polydispersity indices from 1.2 to 3.6 were used. Miniemulsions with three different mean droplet diameters (300, 400, 600 nm) were polymerised and the evolution of particle size was observed. When 300 nm droplets were polymerised they yielded particles of similar diameter to the original droplets, whereas particle coalescence of the growing particles with a loss of control over the particle size distribution was observed for the 400 and 600 nm droplets. The influence of costabiliser, agitation speed, solid content, colloidal protectors and surface coverage on the evolution of the droplet size and size distribution as well as on the evolution of the average particle size and its distribution were examined. It was observed that changing the above parameters had no impact on the evolution of the particle size, suggesting we have a very robust miniemulsion system. [source] Oxidation products of polyunsaturated fatty acids in infant formulas compared to human milk , A preliminary studyMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 12 2008Marie-Caroline Michalski Abstract Information about lipid oxidation in fresh and stored human milk compared with infant formulas is scarce. We aimed to assess n -6 and n -3 PUFA oxidation in these milks by measuring the 4-hydroxynonenal (4-HNE) and 4-hydroxyhexenal (4-HHE) content. Human milk samples (n = 4), obtained from volunteer mothers, were analyzed fresh and after 1 wk at 4°C or 24 h at 18°C. Vitamin E and malondialdehyde (MDA) were measured by HPLC and fatty acid profile by GC. The 4-HHE and 4-HNE contents were measured by GC-MS. Infant formulas (n = 10) were tested; their fat droplet size was measured by laser light scattering and observed by confocal laser scanning microscopy. Human milk samples contained 31.0 ± 6.3 g/L of lipids and 1.14 ± 0.26 mg/L of vitamin E. Fat droplets were smaller in infant formulas than reported in human milk. The (4-HHE/n -3 PUFA) ratio was 0.19 ± 0.01 ,g/g in fresh human milk (unchanged after storage) versus 3.6 ± 3.1 ,g/g in dissolved powder formulas and 4.3 ± 3.8 ,g/g in liquid formula. (4-HNE/n -6 PUFA) was 0.004 ± 0.000 ,g/g in fresh milk (0.03 ± 0.01 ,g/g after storage) versus 1.1 ± 1.0 ,g/g in dissolved powder formulas and 0.2 ± 0.3 ,g/g in liquid formula. Infant formulas also contained more MDA than human milk. n -3 PUFA were more prone to oxidation than n -6 PUFA. Whether threshold levels of 4-HHE and 4-HNE would be of health concern should be elucidated. [source] Inkjet printed, conductive, 25 ,m wide silver tracks on unstructured polyimidePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009Henning Meier Abstract 25 ,m wide, conductive silver tracks on untreated and unstructured polyimide have been produced by inkjet printing using standard 10 pL printheads. This was achieved by reducing the droplet size to ,2 pL by tailoring the waveform and by heating the print cartridge and the substrate to 55 °C. A simple formula was used to predict the track width. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The influence of matrix viscosity and composition on the morphology, rheology, and mechanical properties of thermoplastic elastomer nanocomposites based on EPDM/PPPOLYMER COMPOSITES, Issue 12 2008Ghasem Naderi The morphological and rheological properties of thermoplastic elastomer nanocomposites (TPE nanocomposites) were studied using different viscosities of polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) rubber content (20, 40, 60 wt%). The components, namely EPDM, PP, Cloisite 15A, and maleic anhydride-modified PP as compatibilizer, were compounded by a one-step melt mixing process in a laboratory internal mixer. The structure of the nanocomposites was characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and rheometry in small amplitude oscillatory shear. The distribution state of the clay between the two phases (PP and EPDM) was found to be dependent on the viscosity ratio of PP to EPDM. In the nanocomposites prepared based on low viscosity PP (LVP) and EPDM, the clay was mostly dispersed into the PP phase and the size of the dispersed rubber particles decreased in comparison with unfilled but otherwise similar blends. However, the dispersed elastomer droplet size in the high viscosity PP (HVP) blends containing 40 and 60% EPDM increased with the introduction of the clay. For TPE nanocomposites, the dependence of the storage modulus (G,) on angular frequency (,) followed a clear nonterminal behavior. The increase in the storage modulus and the decrease in the terminal zone slope of the elastic modulus curve were found to be larger in the LVP nanocomposite in comparison with the HVP sample. The yield stress of nanoclay-filled blends prepared with LVP increased more than that of HVP samples. The tensile modulus improved for all nanocomposites but a higher percentage of increase was observed in the case of LVP samples. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Selected experimental methods for determining droplet parameters from the intensity distribution of scattered light: A reviewPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003N. Roth The present paper summarizes some experimental methods, which have been developed using the results of calculations based on the theory of Gustav Mie. As examples two regions of the scattered light are considered in more detail. The intensity distribution in the forward hemisphere for scattering angles 30 , , , 60 shows maxima, which can be identified as regular fringes on a screen. The spacing between the fringes is a measure for the droplet size. In the intensity distribution of the backward hemisphere the region of the first rainbow can be found. In the rainbow region a main maximum, subsidiary maxima and a ripple structure can be identified. The angular position of the main maximum is a measure for the refractive index of the droplet. The angular distance between the subsidiary maxima and the angular distance between the ripples both are a function of droplet size. A comparison with other size measurement methods gives information about the sphericity of the droplet. An evaporating droplet shows for instance oscillations of the rainbow position due to morphology dependent resonances. The oscillation frequency is proportional to the evaporation rate. [source] Prediction of Droplet Velocities and Rain Out in Horizontal Isothermal Free Jet Flows of Air and Viscous Liquid in Stagnant Ambient AirCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2007S. Al Rabadi Abstract Two-dimensional phase Doppler anemometer measurements of droplet size and velocity conducted under several nozzle conditions and a systematic variation of the air mass flow quality and liquid phase viscosity show that the air entrainment process is enhanced when keeping all test conditions constant except for increasing the Newtonian liquid viscosity above of that of water. A two-zone entrainment model based on a variable two-phase entrainment coefficient is proposed with the normalized axial distance allowing for a change in the jet angle. Thus, the jet perimeter is lower and the breakup length is longer in the case of air/relatively higher viscosity liquid phase. It provides the most accurate reproduction of the experimental droplet velocity in comparison with that of other models in the literature and, hence, is recommended for the prediction of the droplet velocity in the case of two-phase air/liquid phase free jet flow in stagnant ambient air. A model for predicting the droplet rain out, considering the droplet trajectories in the free jet flow, allows also for an adequate reproduction of the experimental data. [source] Production of Emulsions in High-Pressure Homogenizers , Part I: Disruption and Stabilization of DropletsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2003S. Tesch In continuous mechanical emulsification, disruption and stabilization of droplets determine the resulting droplet size and, thus, the emulsion's microstructure. Without the need of adding any stabilizer, w/o emulsions provide the possibility of a high viscosity of the continuous phase and, in consequence, of decreasing the probability of coalescence. The present work presents investigations on the production of w/o emulsions in high-pressure homogenizers: the different geometries of standard valve, microfluidizer and orifice valve are compared to each other with reference to disruption and stabilization of droplets. [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] Evaporation of pyrolysis oil: Product distribution and residue char analysisAICHE JOURNAL, Issue 8 2010Guus van Rossum Abstract The evaporation of pyrolysis oil was studied at varying heating rates (,1,106°C/min) with surrounding temperatures up to 850°C. A total product distribution (gas, vapor, and char) was measured using two atomizers with different droplet sizes. It was shown that with very high heating rates (,106°C/min) the amount of char was significantly lowered (,8%, carbon basis) compared to the maximum amount, which was produced at low heating rates using a TGA (,30%, carbon basis; heating rate 1°C/min). The char formation takes place in the 100,350°C liquid temperature range due to polymerization reactions of compounds in the pyrolysis oil. All pyrolysis oil fractions (whole oil, pyrolytic lignin, glucose and aqueous rich/lean phase) showed charring behavior. The pyrolysis oil chars age when subjected to elevated temperatures (,700°C), show similar reactivity toward combustion and steam gasification compared with chars produced during fast pyrolysis of solid biomass. However, the structure is totally different where the pyrolysis oil char is very light and fluffy. To use the produced char in conversion processes (energy or syngas production), it will have to be anchored to a carrier. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [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] | ||||||||||||||||||||||