Cheng, Lai Fung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaf 79). / Abstracts in English and Chinese. / Cheng, Lai Fung. / Chapter Chapter1 --- Introduction --- p.1 / Chapter 1.1 --- Phase diagram determination --- p.1 / Chapter 1.2 --- Formation of a hump in the free energy curve of L in a eutectic alloy --- p.2 / Chapter 1.3 --- Spinodal decomposition --- p.2 / Chapter 1.4 --- Early experience --- p.3 / Chapter 1.5 --- Bulk metallic glasses (BMG) --- p.5 / Chapter 1.6 --- Metal matrix composites (MMC) --- p.6 / Chapter 1.7 --- Liquid state phase separation and the formation of metal matrix comosites by fluxing --- p.6 / Chapter Chapter2 --- Experimental --- p.15 / Chapter 2.1 --- Introduction --- p.15 / Chapter 2.2 --- Preparation of fused silica tube --- p.15 / Chapter 2.3 --- Sample Preparation --- p.16 / Chapter 2.3.1 --- Alloying --- p.16 / Chapter 2.3.2 --- Fluxing --- p.16 / Chapter 2.4 --- Liquidus of Fe-C-Si specimens --- p.16 / Chapter 2.5 --- Microstructure Analysis --- p.17 / Chapter 2.6 --- Mechanical properties --- p.18 / Chapter 2.6.1 --- Hardness test --- p.18 / Chapter 2.6.2 --- Compressive strength --- p.18 / Chapter Chapter3 --- Formation and mechanical properties of Fe86Si14 network alloys --- p.23 / Chapter 3.1 --- Abstract --- p.23 / Chapter 3.2 --- Introduction --- p.24 / Chapter 3.3 --- Experimental --- p.25 / Chapter 3.4 --- Results --- p.27 / Chapter 3.5 --- Discussion --- p.33 / Chapter Chapter4 --- Dependence of mechanical behavior on C concentration in Fe-C-Si network alloys --- p.63 / Chapter 4.1 --- Abstract --- p.63 / Chapter 4.2 --- Introduction --- p.64 / Chapter 4.3 --- Experimental --- p.66 / Chapter 4.4 --- Results --- p.68 / Chapter 4.5 --- Discussions --- p.76

A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in the Department of Chemical Engineering, University of the Witwatersrand. / This work was undertaken to study the growth rate of APT crystals and hence obtain some information on the nucleation rate [Abbreviated Abstract. Open document to view full version] / AC2017

Recent technological advances in computer science have contributed to immense data generation in many critical areas of biology. These data can be used in intelligent information systems to better understand biological processes from the atomic details of biological molecules to the interaction of species in an ecosystem. This thesis presents My Crystal Diary (MCD), an integrated software application designed for use in an intelligent decision-support system for planning novel crystallisation experiments. PostgreSQL database server is the information repository containing both the experimental data and general knowledge. Web-based interfaces developed in Plone provide remote access to the database by utilizing a Zope Web application server.

Recently, we reported the extraction, purification and amino acid sequence of ansocalcin, the major goose eggshell matrix protein. In vitro studies showed that ansocalcin induces spherical calcite crystal aggregates. We designed two peptides using the unique features of the sequence of ansocalcin and the role of these peptides in CaCO₃ crystallization was investigated. The peptides showed similar activities as compared to ansocalcin, but at a higher concentration. The full characterization of the peptides and a rational for the observed morphology for the calcite crystals are discussed in detail. / Singapore-MIT Alliance (SMA)

Thesis (Ph. D.)--School of Pharmacy and Dept. of Chemistry. University of Missouri--Kansas City, 2005. / "A dissertation in pharmaceutical sciences and chemistry." Advisor: Steven H. Neau and Thomas P. Johnston. Typescript. Vita. Description based on contents viewed Mar. 12, 2007; title from "catalog record" of the print edition. Includes bibliographical references (leaves 97-108). Online version of the print edition.

In this study, crystal formation of polypropylene (PP) and poly lactic acid (PLA) in the presence of CO2 in foam extrusion process was investigated using a visualization chamber and a CCD camera. The role of pre-existing crystals on the foaming behavior of PP and PLA were studied by characterizing the foam morphology. Visualization results showed that crystals formed within the die before foaming and these crystals affect the cell nucleation behavior and expansion ratio of PP and PLA significantly. Due to the fast crystallization kinetics of PP, crystallinity should be optimum to achieve uniform cell structure with high cell density and high expansion ratio. In PLA, enhancement of crystallinity is crucial for getting foam with a high expansion ratio. It was also visualized that CO2 significantly suppresses the crystallization temperature in PP through the plasticization effect as well as its influence on flow induced crystallinity.

In this study, crystal formation of polypropylene (PP) and poly lactic acid (PLA) in the presence of CO2 in foam extrusion process was investigated using a visualization chamber and a CCD camera. The role of pre-existing crystals on the foaming behavior of PP and PLA were studied by characterizing the foam morphology. Visualization results showed that crystals formed within the die before foaming and these crystals affect the cell nucleation behavior and expansion ratio of PP and PLA significantly. Due to the fast crystallization kinetics of PP, crystallinity should be optimum to achieve uniform cell structure with high cell density and high expansion ratio. In PLA, enhancement of crystallinity is crucial for getting foam with a high expansion ratio. It was also visualized that CO2 significantly suppresses the crystallization temperature in PP through the plasticization effect as well as its influence on flow induced crystallinity.

The irradiation of metallic glasses to induce nanocrystallization was studied in two metallic glass compositions, Cu50Zr45Ti5 and Zr55Cu30Al10Ni5. Atomic mobility was described using a model based on localized excess free volume due to displace- ment cascades created by energetic particle irradiation. Due to the di erence in cascade size among di erent masses of projectiles, a mass-dependent study was per- formed. Metallic glass ribbon samples produced by melt-spinning were bombarded with electron, He, Ar, and Cu particles. Electron irradiation and characterization was performed "in-situ" by means of transmission electron microscopy. The di erent metallic glasses showed dissimilar levels of radiation stability under electron irradi- ation by Cu50Zr45Ti5 forming crystals 1-10 nm in diameter embedded in the amor- phous matrix after about 30 minutes of irradiation, while Zr55Cu30Al10Ni5 showed no such crystallization. Increasing projectile mass caused an increase in the maximum nanocrystal diameter up to approximately 100 nm in Cu irradiated Zr55Cu30Al10Ni5. Studies of di raction patterns of irradiated specimens showed nucleation of Cu10Zr7 phases in both specimens, as well as evidence of CuZr2 in Cu50Zr45Ti5 and both CuZr2 and NiZr2 in Zr55Cu30Al10Ni5. Crystal sizes in irradiated Zr55Cu30Al10Ni5 specimens showed bimodal distribution with many large (50-100 nm) crystals and many small (1-5 nm) crystals. The small crystals in irradiated Zr55Cu30Al10Ni5 were determined to be NiZr2 phase because of the low abundance of Ni. After exposure to 2 keV Ar ions, areas of composition roughly Cu10Zr7 were found by energy-dispersive X-ray spectroscopy but no crystallization was found. Further crystallization was achieved in decomposed specimens after electron irradiation. This shows that atomic segregation is a necessary step before nucleation in metallic glasses.

Colloidal crystallization in sedimenting systems is an incompletely understood process, where the influence of interparticle forces on the three-dimensional (3-D) microstructure remains to be fully elucidated. This dissertation outlines work that is intended to improve our knowledge of this subject by studying sedimentation equilibrium and phase behavior for electrostatically repulsive systems, as well as the interfacial crystallization of attractive depletion systems. Towards this end, several analytical and experimental tools have been developed to explore the thermodynamic behavior of these systems. For example, the experimental challenges necessitated the development and implementation of the following in this work: (1) core/shell silica particles incorporating molecular fluorophores or semiconductor nanocrystals; (2) modification of silica particle surfaces; (3) the design of specialized sedimentation cells; and (4) the development of a novel fluorescent intensity-based approach to quantifying colloidal sediments. Analysis of the experimental data required the use of the following tools: (1) location of particle centers from images; (2) deconvolution of intensity profiles using a novel Monte Carlo-type algorithm; and (3) prediction of colloidal phase diagrams using perturbation theory. On the basis of this work’s experimental and simulation data, it is concluded that competing orientations of crystal grains may suppress crystallization at grain boundaries, resulting in a non-uniform depth of the fluid/solid transition. Also, it was demonstrated that the grain size in depletion crystals formed from quantum dot-coated silica particles can be increased by localized annealing with the confocal microscope’s laser. Additional findings include the ability of the intensity-based approach to measure interparticle forces in colloidal sediments, as well as the inability to use perturbation theory to predict two-dimensional colloidal fluid/solid transitions. While significant progress has been achieved, work on 3-D imaging of colloidal depletion crystals in a refractive index-match medium is ongoing. This work improves our understanding of 3-D colloidal crystallization at interfaces, as well as provides new tools for future research. Also, this work demonstrates a potential route for zone refining of colloidal crystals, a technique that may be important in the search for low-defect 3-D arrays that can be used as templates for photonic bandgap materials.

Thesis (Ph. D.)--University of North Texas, Aug., 2009. / Title from title page display. Includes bibliographical references.