Lutetium 177 ions were implanted in iron and nickel foils using a mass separator. The rotations of the angular correlation pattern caused by the hyperfine fields acting on the implanted nuclei were measured for the 71-250 keV and the 208-113 keV cascades in the beta-decay product Hafnium 177. Using measured data, the g-factor for the 250 keV spin 11/2, second excited state in Hf177 was determined, as were the internal fields acting on the Hf177 impurity in iron and nickel. The results are as follows: g11/2 = 0.277 ± 0.080 HFe(int) = -133 ± 7 k0e HNi(int) = -58.6 ± 8 k0e / Thesis / Master of Science (MSc)

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<p> The macroscopic mechanical behaviour of alloys is intimately related to their structure at the atomic level. The influence of small (<0.1μ) ordered coherent particles (𝛄') on the mechanical properties of Ni-Al alloys has been studied. The maximum strength of polycrystals occurs at 0.45 volume fraction 𝛄' and grain boundary embrittlement occurs at higher volume fractions. It was shown that long range order in the particles affects strength by increasing the anti-phase boundary energy. In monocrystals the deformation behaviour is strongly influenced by the amount of particles present. </p> <p> By growing very large particles of 𝛄' (~1.0μ) dislocation-particle interactions have been studied. Stacking faults have been observed in the particles whose bounding dislocation Burgers vectors were determined. By suitable heat treatment still larger 𝛄' particles (~10µ) were formed which had incoherent interfaces. The dislocation networks at the interfaces were analysed. </p> / Thesis / Doctor of Philosophy (PhD)

<p> The present work is aimed at studying the oxidation of thin films of nickel, nichrome and nickel phosphorous in air and water vapour at temperatures ranging from 100°C to 500°C. The optical constants, i.e., refractive index n and extinction coefficient k for these materials have been determined and their variation with temperature has been studied using ellipsometric technique. It has been shown that nickel oxide (NiO) is the more predominant phase in the oxides formed on these materials. It has also been found that within experimental error, the water vapour does not play a vital role in the oxidation process.</p> / Thesis / Master of Science (MSc)

<p> Conditions for the precipitation of nickel salicylaldoximate from homogeneous solution were examined and procedures were recommended for the determination of nickel when present alone or mixed with some diverse ions. </p> <p> The reaction between salicylaldehyde and hydroxylamine was studied in aqueous solution and some of the reaction parameters were evaluated. </p> / Thesis / Master of Science (MSc)

Nickel (Ni) is a metal that is anthropogenically enriched in aquatic settings. It has been reported as having three main modes of toxicity in freshwater animals (ionoregulatory disturbance, respiratory impairment, and the generation of oxidative damage), but there is little understanding of Ni toxicity in marine and estuarine environments. The mechanism(s) of Ni uptake and toxicity were investigated using three model species (adult green shore crab, Carcinus maenas; adult Atlantic killifish, Fundulus heteroclitus; early life-stages of the New Zealand sea urchin Evechinus chloroticus). In crabs, sea water protected against Ni accumulation and toxicity. In more dilute salinities, however, all three modes of Ni toxicity were identified at a sub-lethal level, with effects noted at Ni exposure levels as low as 8.2 µg/L, the US EPA environmental regulatory limit. In killifish, similar protective effects of SW were observed, however this species was much more resilient to Ni toxicity, with only minor changes in ionoregulation and oxidative stress noted, and no evidence of respiratory toxicity. Sea urchin larvae were found to be the most sensitive marine organisms to Ni toxicity yet reported, with a 96 h median effect concentration of 14.1 µg/L measured. Toxicity in this species was related to Ni impairment of calcium influx, consistent with proposed mechanisms of uptake observed in the other two models. Overall, the elevated ion levels associated with salinity were shown to be protective, suggesting a role for water chemistry in modifying Ni accumulation. However, physiology, which varies between species, developmental stages, and as a function of environmental salinity, also influenced organism sensitivity to Ni. These data contribute novel information regarding the relationships between water chemistry, Ni accumulation, and Ni toxicity, and as such, will be integral in the future development of predictive modelling tools for protecting marine and estuarine animals against environmental Ni. / Thesis / Doctor of Science (PhD)

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No description available.

No description available.

No description available.