No description available.

Abstract not available

For thesis abstract select View Thesis Title, Contents and Abstract

Quartz particles of various discrete particle size ranges have been methylated to varying known mounts using trimethylchlorosilane and their flotation behaviour has been assessed in a modification of the Hallimond tube. For each particle size there is a definite degree of. surface coverage below which the particles do not float. A 'flotation domain' is identified which shorvs that both coarse (-100pm) and fine (-10pm) particles require a greater degree of surface coverage to initiate flotation than do intermediate (-40pm) particles. Water contact angles have been measured on quartz plates and powders which have been methylated (under the same conditions) with trimethylchlorosilane. Both advancing and receding water contact angles measured on quartz plates as a function of degree of surface methylationare in good agreement with the angles predicted by the Cassie equation. Advancing water contact angles measured on quartz particles as a function of degree of surface methylation are also in good agreement with angles predicted by the Cassie equation up to surface coverages of'about 70%. The angles measured at higher surface coverages are less than those anticipated by the Cassie equation. The flotation behaviour of the particles has been compared with that predicted by existing flotation theories. It has been shown that coarse particle behaviour is predicted by the kinetic theory of flotation proposed by Schulze. Fine particle behaviour, however, only qualitatively agrees with Scheludko's theory of fine particle behaviour. Calculated induction times, in conjunction with observed flotation behaviour, indicate that the bubble-particle attachment process is most efficient for particles of about 38pm in diameter ander the set experimental conditions used in this study. Flotation rate trials were performed for three particle size ranges and rate constants were evaluated for the various degrees of surface coverage. It was found that the dependence of rate constant on particle size is essentially linear.

No description available.

In this work a plasma torch system has been setup. Using the methane as gas source, carbon atoms were ionized and diamond nanoparticles were synthesized. Argon or nitrogen gas was applied as carrying gas for dilution methane. By means of Field-emission scanning electron microscopy (FE-SEM), X-ray Diffraction (XRD), Raman Scattering, Transmission Electron Microscopy (TEM) and Transmission Electron Diffraction (TED) diamond nanoparticles were characterized. The system is characteristic structured with a MP system interior with an antenna. The microwave was guided in chamber and to the antenna tip, and induced the microwave energy gather on the tip then induces plasma under higher pressure. Expect sample N01 that used nitrogen carrying gas and gas flow rate was 0.6 L/min, the particles all have the size between 25-50nm from the analysis of the morphology of the particles by SEM. The particles size increased along with the carrying gas flow rate as well as the pressure increased. The materials structure has been analyzed by Raman, XRD. The natural diamond structure has been found synthesizing the nanoparticles under the high pressure or the higher catalyst gas flow rate. And as carrying gas effect, nitrogen is better than Argon. The electron beam energy would destroy the structure of diamond nanoparticles during TEM analysis and diamond nanoparticles changed from single crystal to amorphous has been observed by TED analysis.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 110-114).

Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. Includes bibliographical references (leaves 120-126).

The spray freezing into liquid (SFL) and thin film freezing (TFF) processes were utilized to produce 300 nm protein particles with surface areas on the order of 31 - 73 m²/g and 100% protein activities. Despite a cooling rate of ~10²-10³ K/s in SFL and TFF, the particle sizes and surface areas were similar to those observed in the widely reported process, spray freeze-drying (SFD), where cooling rates reach 10⁶ K/s. In SFL and TFF, the thin liquid channels between the ice domains were sufficiently thin and freezing rates of the thin channels sufficiently fast to achieve the similar particle morphologies. Therefore, the extremely rapid cooling rate in the SFD process was not necessary to form the desired submicron protein particles. In SFL and TFF the surface area/volume ratio of the gas-liquid formed on the liquid protein formulations (46-600 cm⁻¹) was 1-2 orders of magnitude lower than in SFD (6000 cm⁻¹), leading to far less protein adsorption and aggregation. This larger exposure to the gas-liquid interface resulted in lower protein activities in SFD. Although protein stabilities are high in conventional lyophilization, cooling rates are on the order of 1 K/min resulting in large 30 to 100 [mu]m sized particles. Thus, the intermediate cooling rate regime for SFL and TFF, relative to SFD and lyophilization, offers a promising route to form stable submicron protein particles of interest in pulmonary and parenteral delivery applications. The rod-shaped protein particles produced by SFL and TFF are beneficial for forming suspensions stable against settling in hydrofluoroalkanes (HFA) for pressurized metered dose inhaler (pMDI) delivery. The flocculated rods are templated by atomized HFA droplets that evaporate and shrink to form particles with optimal aerodynamic diameters for deep lung delivery. Fine particle fractions of 38-48% were achieved. This novel concept for forming stable suspensions of flocs of rod shaped particles, and templating and shrinking the flocs to produce particles for efficient pMDI deep lung delivery is applicable to a wide variety of drugs. / text