School of Chemistry - Theses
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ItemModel chemistry relevant to the molybdenum copper active site of CO dehydrogenase(University of Melbourne, 2007)
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ItemToward the synthesis and analysis of selenium-containing glucocorticoid prodrugs(University of Melbourne, 2007)
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ItemNMR studies of amyloid ab-peptide in membranes(University of Melbourne, 2006)
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ItemSynthesis and optical properties of CdSe core and core/shell nanocrystals( 2008)The synthesis of nanocrystals is unique compared to the formation of larger micron-sizesspecies as the final crystal sizes are not much larger than the primary nuclei. As a consequencethe final outcome of a nanocrystal synthesis i.e mean crystal size, concentrationand standard deviation is almost solely determined by the end of the nucleation phase. Directingthe growth of crystals beginning from aggregates of only tens of atoms into maturemonodisperse nanocrystals requires that the governing kinetics are strictly controlled at everymoment of the reaction. To effect this task various different ligands need to be employed,each performing a particular function during both nucleation and growth. (For complete abstract open document)
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ItemThe adsorption of polydisperse nonionic surfactants at the solid/aqueous interface( 1987)A high resolution capillary gas chromatography technique has been adapted to the analysis of polydisperse non-ionic surfactants. This technique has enabled the complete characterization of the oligomer distributions of very small samples of surfactants (typically 0.1 µg to 0.5 µg). It has made possible the determination of changes in the oligomer distribution on adsorption of surfactant at the solid/aqueous interface. Isotherms have been measured for the adsorption of a series of polyoxyethylene nonylphenol surfactants from aqueous solution on to various solids. These isotherms indicate that the surfactant – surface interaction increases with an increase in the hydrophobicity of the adsorbent. They also show a dependence upon the average length of the ethylene oxide chain and the ratio of the surface area/solution volume. These latter factors affect both the total partition of surfactant between the surface and the solution, and also the selectivity of the solid surface. A detailed study of the adsorption of N8 (a commercial non-ionic surfactant) by a precipitated silica at various surface area/solution ratios, has been undertaken, where the equilibrium surfactant oligomer distributions in the adsorbed and solution phases have been determined. At surfactant concentrations above the critical micelle concentration, the phase separation approach has been used to estimate the surfactant oligomer distributions in free monomer solution and in micelles. This information has been combined with a surface phase model to interpret the results of the adsorption distribution studies.
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ItemThe structure of the oxide/aqueous electrolyte interface( 1975)The structure of the oxide/aqueous electrolyte interface has been studied. The surface porosity of several oxides to ions is evaluated and the contribution of such porosity to the double layer properties determined by surface charge measurements. The oxides studied are B.D.H. precipitated silica, before and after heat treatment, rutile, goethite, hematite and amorphous ferric oxide. The surface porosity was evaluated using nitrogen adsorption for physical porosity, tritium exchange for surface hydration and dissolution for surface crystallinity. It is found that the surfaces of metal oxides may be divided into two categories; those that are porous to ions and those that are non-porous. Of those studied only the precipitated silica and the amorphous ferric oxide are porous. The porosity is probably due to an easily permeated layer of hydrolysed oxidic material. It does lead to exceptionally high surface charges. However the non-porous oxides also exhibit high surface charges so that while surface porosity may, in some cases, contribute to oxide double layer properties, it cannot be a general explanation of the high differential capacities observed. A site-binding model for non-porous oxide/aqueous electrolyte interfaces is introduced, in which it is proposed that the adsorbed counter ions form interfacial ion pairs with discrete charged surface groups. This model is used to calculate theoretical surface charge densities and potentials at the Outer Helmholtz Plane. The calculated values are consistent with experimental data for oxides provided a high value of the inner zone capacity is accepted. An explanation is provided for the difference between silica and most other oxides in terms of the dissociation constants of the surface groups.
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ItemSpectroscopic studies of gas phase ion-neutral interactions( 2007-10)Gas phase experimental and computational investigations are described for F--H2 and the halide-methane complexes and clusters, F--(CH4)n and Cl--(CH4)n. Vibrational predissociation spectroscopy in conjunction with tandem mass spectrometry are used to obtain mid-infrared spectra of each complex in the ligand’s hydrogen stretch region. Ab initio calculations are used to predict structures, binding energies and vibrational frequencies and intensities. By examining the changes in both the vibrational frequencies and intensities of the neutral moiety upon complexation with the anion, and comparing these with the theoretical predictions, structures are able to be inferred. (For complete abstract open document)
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ItemThe coordination of nickel in hyperaccumulating plants( 2007-10)The co-ordination of Ni in hyperaccumulator plants was investigated using a number of mass spectrometry (MS)-based analytical techniques. Initial field studies on nickeliferous (lateritic) soils in Western Australia failed to identify plants containing elevated metal concentrations. For this reason, Ni-hyperaccumulators were collected from known ultramafic sites in New Caledonia, as well as grown under controlled conditions. Using electrospray ionization MS a Ni-nicotianamine (Ni-NA) complex [NiII(C12H20N3O6)]+ was identified in the South African Ni-hyperaccumulator Berkheya coddii. The association between Ni and NA was examined further in a range of Thlaspi species which accumulate different concentrations of Ni and Zn in their foliar tissues. In order to quantitate the concentration of NA a new liquid chromatography-MS (LC-MS) based analytical protocol was developed which allowed the quantification of NA and free amino acids. From the analysis of the leaf tissue in Thlaspi a strong correlation emerged between Ni and NA but not Zn. This suggested that NA plays a role in the transport of Ni in Ni-hyperaccumulating Thlaspi plants. An inverse proportionality was found between Fe and Ni. Higher NA production could be related to maintenance of Fe homeostasis. A correlation was also found between Zn and asparagine. These results are consistent with the operation of separate transport mechanisms for Ni and Zn. Further extreme examples of Ni-hyperaccumulation were also examined using LC-MS and metabolite profiling based on gas chromatography-MS (GC-MS). (For complete abstract open document)
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ItemIon trap studies of single microparticles: optical resonances and mass spectrometry( 2006-12)Microparticle experiments conducted using a newly commissioned quadrupole ion trap (QIT) are reported. Single polystyrene microparticles are confined using three dimensional electrodynamic quadrupole fields and characterised by their fluorescence emission and secular frequency measurements. The advantages of this confinement technique are that single particle properties can be measured free from ensemble averaging effects and unperturbed by solvents and (or) substrates. (For complete abstract open document)
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ItemHigh power carbon-based supercapacitors( 2006)Energy storage devices are generally evaluated on two main requirements; power and energy. In supercapacitors these two performance criteria are altered by the capacitance, resistance and voltage. (For complete abstract open document)