Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 46 for “"particle growth"”.
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Formation of uniform particles: Morphology and colloidal stability, and stable particle growth during precipitation from titanium alkoxides
The mechanisms of formation of uniform particles from hydrolysis and condensation of titanium alkoxides are investigated. Evidence is presented suggesting two separate processes are determining the success of precipitating uniform particles: generating and maintaining a stable suspension throughout …
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Precipitation of barium carbonate nanoparticles within water-in-oil microemulsion systems: relations between particle growth and surfactant environment
Contains fulltext : 72087.pdf (Publisher’s version ) (Open Access)
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RNA-Mediated Synthesis of Particles from Organometallic Palladium and Platinum Precursors
… sequences have been discovered that mediate the growth of hexagonal, cubic and spherical palladium and platinum containing particles. In vitro selection techniques were used to evolve an initial library of ˜ 3 x 10¹³ unique RNA sequences through six to ten cycles of selection to yield several …
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The precipitation of uniform silica particles through the controlled hydrolysis of silicon alkoxides
The formation of uniform silica particles by the alkoxide route has been investigated. Rates of chemical reactions involved in the precipitation are reported and linked to particle growth rates. Seeded growth experiments indicate that reactions between soluble species occur at rates that are …
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Synthesis and characterization of infrared quantum dots
… nanocrystal community, classical nucleation and growth is often invoked to explain size focusing. However, this model lacks predictive power and contradicts what is known about the chemistry of QD growth. I try to relate my experimental approach and my conclusions to our understanding of the …
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Vapor scavenging by atmospheric aerosol particles
Particle growth due to vapor scavenging was studied using both experimental and computational techniques. Vapor scavenging by particles is an important physical process in the atmosphere because it can result in changes to particle properties (e.g., size, shape, composition, and activity) and, …
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Solar receiver coating development: the synthesis and growth of copper chromite spinel particles across sol-gel routes and calcination profiles
… synthesis routes for the creation of CuCr2O4 particles that exhibit adequate sinterability for developing robust solar receiver coatings that can prevent oxidation. The Pechini and modified Pechini sol-gel methods were directly compared as two routes for nanoparticle creation. Particle growth …
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Ambient measurements of chemical and physical properties of organic aerosols: Insights into formation, growth, and heterogeneous chemistry
… Carolina. Two events were identified in which particle growth, presumably by gas-to-particle conversion, was dominated by accumulation of organic aerosol mass. Growth rates between 1.2 nm hr-1 and 4.9 nm hr-1 were observed. Using a mass-spectral deconvolution method coupled with linear …
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In-situ steric stabilization of ultrafine titania particles synthesized by a sol-gel process
… concerns the synthesis of ultra-fine titania particles starting with titanium ethoxide as a precursor. The particle size and morphology was controlled using polymeric stabilizers which imparted in-situ steric stability during the particle growth. An attempt was made to elucidate the factors …
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In-Situ Studies of Copper Nanoparticles Using a Novel Tandem Ultra-High Vacuum Particle Production Chamber Transmission Electron Microscope
Nanophase materials, a compaction of nano-particles, are arguably a new phase of matter whose high grain-boundary-to-volume ratio leads to new and enhanced material properties. Previously, these materials have been difficult to study because of their sensitivity to contaminating atmospheres. We …
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Molecular pathways of silica nanoparticle formation and biosilicification
Biosilicification and silica nanoparticle formation occur in many modem terrestrial environments and they also played an important role in ancient geological settings. This thesis presents results from (i) field studies in Icelandic geothermal waters that aimed at quantifying the parameters that …
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Synthesis and shape control of functionalized cadmium telluride nanoparticles
… and water soluble cadmium telluride nanoparticles by a facile hybrid solution high temperature method is presented. This method involves the reaction by the addition of an aqueous suspension or solution of a cadmium salt (chloride, acetate, nitrate or carbonate) to a freshly prepared …
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CFD Modeling of nanoparticle formation in a plasma synthesis reactor
… a quenching process. The model accounts for particle formation by nucleation and growth by condensation and brownian coagulation. Transport of particles occurs by convection, thermophoresis, and brownian diffusion. Axial and radial diffusion of particles are considered. The commercially …
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Influence of particle size and morphology of Pt₃Co/C on the oxygen reduction reaction
… understanding of the influence of Pt alloy particle size and active surface morphology on the ORR activity. The Pt alloy that was investigated was Pt₃Co/C. The surface morphology was modified by varying the Pt/Pt₃Co loading on a carbon support. The catalysts were prepared using thermally …
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Supercritical fluid spray processes for microencapsulation and formation of submicron aqueous dispersions of pharmaceutical compounds
… fluids that are capable of producing submicron particles. Novel variations of these basic processes have been examined to produce stable particles of various pharmaceutical compounds. PCA is an antisolvent precipitation technique where an organic solution of drug + polymer in solvent is atomized …
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Precipitation of ultrafine particles using liquid antisolvent with concentric ultrasonic nozzle and subcritical CO2
… fluids. Hence, it is necessary to reduce the particle size, which increases the interfacial surface area. This work focuses on micronization of class ii drug Griseofulvin which is poorly water soluble. Two processes namely, liquid antisolvent precipitation using ultrasonic nozzle and other …
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Electrospun carbon nanofiber electrodes decorated with palladium metal nanoparticles : fabrication and characterization
… amorphous carbon and precipitating nanoparticles of palladium in a homogeneous distribution throughout the electrode. The electrode was characterized using scanning electron microscopy (SEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), microprobe station, and x-ray …
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Sub 2 nm Particle Characterization in Systems with Aerosol Formation and Growth
… frontier is characterizing the initial stages of particle formation by real time measurement of particles below 2 nm in size. Sub 2 nm particles play important roles by acting as seeds for particle growth, ultimately determining the final properties of the generated particles. Tailoring …
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Synthesis and characterization of cathode catalysts for use in direct methanol fuels cells
… effectively reduced and deposited Pt nanoparticles onto different carbon supports. Functionalization of some of the supports was also successfully carried out through acid oxidative treatment which introduced carboxylic acid and hydroxyl groups onto the surface of the supporting material, …
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Particulate matter formation in spark-ignition engines
… the effect of transient engine conditions on particle growth and dynamics. Particle dynamics in diluted SI and compression ignition (Cl) engine exhaust are examined and discussed in the context of SI exhaust dilution. Temperature measurements in the exhaust pipe and dilution tunnel reveal the …
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