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Initial Particle Size (initial + particle_size)
Selected AbstractsSynthesis and characterization of hybrid nanocomposites comprising poly(vinyl alcohol) and colloidal silicaADVANCES IN POLYMER TECHNOLOGY, Issue 3 2008Mousumi De Sarkar Abstract Organic,inorganic hybrid composite films were developed using poly(vinyl alcohol) (PVA) and an aqueous dispersion of colloidal silica of initial particle size of 15,30 nm. The hybrid films, prepared with varied proportion of colloidal silica (10,90 phr), were found to be transparent, indicating the nanolevel dispersion of the inorganic component over the polymer. Morphological studies further revealed no significant agglomeration of the silica domains embedded into the polymer matrix. A depression in glass transition temperature of PVA is observed with increasing proportion of silica. The degree of crystallinity also showed a decreasing trend with increasing amount of silica. However, the composite films demonstrated superior mechanical performances, higher resistances to dissolution in boiling water, and lower permeability compared with virgin PVA, owing to the better interaction between PVA and silica as well as the reinforcing action of nanosilica particles in the polymer matrix. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:152,162, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20129 [source] Nanoparticle formation through solid-fed flame synthesis: Experiment and modelingAICHE JOURNAL, Issue 4 2009W. Widiyastuti Abstract The preparation of silica nanoparticles through solid-fed flame synthesis was investigated experimentally and theoretically. Monodispersed submicrometer- and micrometer-sized silica powders were selected as solid precursors for feeding into a flame reactor. The effects of flame temperature, residence time, and precursor particle size were investigated systematically. Silica nanoparticles were formed by the nucleation, coagulation, and surface growth of the generated silica vapors due to the solid precursor evaporation. Numerical modeling was conducted to describe the mechanism of nanoparticle formation. Evaporation of the initial silica particles was considered in the modeling, accounting for its size evolution. Simultaneous mass transfer modeling due to the silica evaporation was solved in combination with a general dynamics equation solution. The modeling and experimental results were in agreement. Both results showed that the methane flow rate, carrier gas flow rate, and initial particle size influenced the effectiveness of nanoparticle formation in solid-fed flame synthesis. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] A practical approach to the use of nanoparticles for vaccine deliveryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2006Janet Wendorf Abstract The objective of this work was to obtain a nanoparticle formulation that could be sterile filtered, lyophilized, and resuspended to the initial size with excipients appropriate for use as a vaccine formulation. Poly(lactide-co-glycolide) (PLG) polymers were used to create nanoparticles ranging in size from 110 to 230 nm. Protein antigens were adsorbed to the particles; the protein-nanoparticles were then lyophilized with the excipients. Vaccine compatible excipient combinations of sugars alone, surfactants alone, and sugars and surfactants were tested to find conditions where initial particle size was recovered. Sterile filtration of smaller nanoparticles led to minimal PLG losses and allowed the particle preparation to be a nonaseptic process. We found that the smaller nanoparticles of size ,,120 nm, required higher surfactant concentration to resuspend postlyophilization than slightly larger (,220 nm) particles. To resuspend 120 nm nanoparticles formulations of poly(vinyl alcohol) (PVA) with sucrose/mannitol or dioctyl sodium sulfosuccinate (DSS) with trehalose/mannitol were sufficient. The protein-nanoparticles resuspension with the same excipients was dependent on the protein and protein loading level. The nanoparticle formulations in vivo were either similar or had enhanced immunogenicity compared to aluminum hydroxide formulations. A lyophilized nanoparticle formulation with adsorbed protein antigen and minimal excipients is an effective vaccine delivery system. Copyright © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:2738,2750, 2006 [source] The effect of an enzymatic pretreatment on the hydrolysis and size reduction of fat particles in slaughterhouse wastewaterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2001L Masse Abstract The effect of an enzymatic pretreatment, Pancreatic Lipase 250 (PL-250), on the hydrolysis and size reduction of fat particles in slaughterhouse wastewater was characterised for enzyme doses ranging from 125 to 1000,mg,dm,3 and initial particle sizes (Din) varying between 53 and 383,µm. Treatment with PL-250 significantly reduced the size of pork fat particles in slaughterhouse wastewater. Particle size reduction increased with Din, possibly due to the more filamentous and plate-like configuration of the larger fat particles, which could be easily broken at weak points. The smaller particles were observed to be denser and more spherical. Size reduction also increased with enzyme concentration, but the benefit of adding more enzyme diminished greatly as enzyme dose was increased. The maximum long-chain fatty acid (LCFA) concentration in filtered samples was detected after 4,7,h of treatment and ranged from 8.2 to 34.9,mg,dm,3. The linear rate of LCFA released in solution during enzymatic pretreatment ranged from 39.4 to 169.9,mg,dm,3 d,1, and increased with enzyme concentration up to 500,mg,dm,3. At a PL-250 concentration of 1000,mg,dm,3, the LCFA release rate decreased, maybe due to excessive layering of adsorbed enzyme on the fat particles or increased degradation of released LCFAs. The pretreatment appeared to be more efficient with beef than pork fat particles. However, the effect of an enzymatic pretreatment on a downstream anaerobic treatment of slaughterhouse wastewater containing fat particles remains to be tested. © 2001 Society of Chemical Industry [source] Catalytic decomposition of methane over supported Ni catalysts with different particle sizesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Sun Yunfei Abstract Methane decomposition on ,-Al2O3 -supported Ni catalysts, as a method for the production of carbon nanofibers (CNFs) and CO-free hydrogen, has been investigated to show the effect of catalyst particle size on the rate and yield of CNFs formation. The catalysts were prepared by deposition,precipitation with different calcination temperature ranging from 725 to 1025 K so as to have different initial particle sizes. The results show that catalysts with smaller initial particle sizes had higher initial growth rate but experienced fast deactivation. The lifetime of the catalyst, ending at the inflection point on the rate curve of CNFs growth, could well represent the yield of CNFs of the catalyst, and the maximal yield of CNFs was achieved on the Ni catalysts calcinated at 823 K and with a particle size of around 56 nm. However, the diameters of the grown CNFs were not directly related to the initial size of the catalysts, because of particle sintering and breaking during catalyst reduction or CNFs formation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||