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CD containing a copy of the thesis, software and extra documentation is held with print copy. / Nuclear Magnetic Resonance (NMR) is a relatively complex technique and normally requires expensive equipment. However, with advances in computing, electronics and permanent magnet technologies, NMR is becoming more feasible as a non-invasive tool for industry. The strength of NMR is its ability to probe at the molecular level and hence gain information about molecular structure, organisation, abundance and orientation. This thesis describes the development of an instrumentation platform technology that is compact and therefore portable. It has been produced to aid the development of NMR based tools or sensors for research and industry and will lead to a series of low cost, portable NMR systems for the non-destructive testing of materials such as polymer composites, rubber, timber, bricks and concrete. The instrumentation is largely electronics based and consists of a series of modules that can be interconnected to produce a solution. The first of two main modules is called the system core. What is common to all NMR applications is the generation of precisely timed signals, the capturing of signals and the processing/display of data. This has been implemented by developing a general purpose Digital Signal Processor (DSP) based instrumentation and control module that uses a Universal Serial Bus interface to communicate with a host computer. A graphical user interface is provided by an application running under Windows® XP. The second main module is a radio frequency transceiver that has been developed using digital receiver technology. The signals, after some amplification, are digitized with a 14-bit, 62.5MH.z analogue to digital converter. The sampled signal is then mixed digitally with synthesized sine and cosine functions to generate lower frequency quadrature outputs which are then digitally filtered and decimated before being passed onto the DSP for further processing and storage. A direct digital synthesizer with an analogue output is used to generate any required excitation signals. All synthesizers have phase and frequency hopping capabilities and are phase locked to each other and the DSP. The system was designed to interface to a range of NMR probes. The type of probe is determined by the intended application and each probe has specific requirements such as the type of radio frequency power amplifier, duplexer and preamplifier needed. This results in a number of instrumentation variations and a modular instrument enclosure was used to cater for these variations. The instrument was first configured for an NMR probe called the NMR-MOUSE. Tests were performed with this probe to verify the correct operation and performance of the instrument. The instrument was then reconfigured for a new probe called the NMR-MOLE and further testing was performed. This probe was still undergoing development and had not been previously tested. Finally, a dedicated compact instrument measuring 360 x 240 x 55 mm and weighing 3.6 kg was developed for the NMR-MOUSE probe.

The hydrophobicity of a surface is an important property in many areas of science and engineering. This is especially the case in mineral processing, where differences in surface hydrophobicity lie at the heart of the separation process of flotation. Chemicals are used to increase and decrease the natural hydrophobicity of minerals to attain a better separation between valuable and worthless material. Polymers are often used to reduce mineral surface hydrophobicity. Decades of empirically based decision making have produced a list of effective depressants. However the detailed study of how these polymer depressants affect surface hydrophobicity and mineral recovery lags behind applied investigations. The aim of this thesis was to study the adsorption of commonly used depressants on model surfaces and to interrogate the action of these polymers in reducing surface hydrophobicity. We have modelled the degree of hydrophobicity of common minerals in order to study polymer depressants with methods not commonly used in studies of surface characterisation in flotation. The model surfaces (self-assembled monolayers, SAMs) allowed us to use the quartz crystal microbalance with dissipation monitoring (QCM-D) to study the adsorption of polymers. The QCM-D can be used to obtain adsorption isotherms, adsorption kinetics, water content of adsorbed layers, and information on the conformation of the adsorbed polymer. The results from the QCM-D were correlated with the contact angle data from the captive bubble measurements, with which we assessed the hydrophobicity of the surface before and after polymer adsorption. Three of the polymers layers were probed with dynamic dewetting studies, in order to test other modes of depressant action. Three types of polymers were studied - a polyacrylamide (Polymer-H), a polyelectrolyte CMC (carboxymethyl cellulose) and a group of dextrins (Dextrin-TY, a phenyl succinate substituted dextrin (PS Dextrin) and a styrene oxide substituted dextrin (SO Dextrin)). These polymers are commonly used or have potential to be used in the depression of talc and graphite. Polymer-H was used to investigate the hydrophobic bonding between a non-ionic polymer depressant and chemically inert and non charged surfaces by probing the influence of substrate hydrophobicity on polymer adsorption and reduction of contact angle. Three different model surfaces were used (mixed self-assembled 0.5 SAM, 0.7 SAM or single self-assembled 1.0 SAM monolayers) with advancing contact angles between 75?? and 119??. The study of Polymer-H found that the substrate hydrophobicity is an important factor in adsorption of this polymer and the change in contact angle upon adsorption depends on adsorbed amount. The effectiveness of Polymer-H to reduce surface hydrophobicity was established to correlate with its conformation and morphology. CMC was investigated to find out how a stimulus responsive polymer depressant can be used in flotation. It was established that the adsorbed amount and rate of adsorption of CMC increase with decreasing of pH or increasing of ionic strength. It was shown that the surface hydrophobicity of a CMC pre-adsorbed layer changes with the environment and these alterations are fully reversible. A switch of ionic strength (from 10-2 M KCl to 10-1 M KCl) caused partial dehydration of the adsorbed layer and a decrease of the receding contact angle by 20??. A pH switch (pH = 9 to pH = 3) resulted in a 40?? change in receding contact angle. The CMC investigation showed that the use of a stimulus responsive polymer presents opportunities for exploiting solution conditions as a means to effect a better mineral separation in flotation The adsorption of three dextrin-based polymers on a model hydrophobic surface has been characterized using the quartz crystal microbalance with dissipation monitoring (QCM-D). The three polymers (one standard dextrin and two dextrins with different aromatic group substitutions) exhibited varying affinities and capacity for adsorption on the hydrophobic substrate. The effect of the three polymers on the static contact angle of the surface was studied using captive bubble contact angle measurements. The three polymers were seen to reduce the receding contact angle by similar amounts (approximately 14 degrees) in spite of having varying adsorbed amounts and differences in adsorbed layer water content. Although no differences were observed in the ability of the polymers to reduce the static contact angle, measurements of the dewetting dynamics between a rising air bubble and the polymer covered substrate yielded stark differences between the polymers, with one polymer slowing the dewetting dynamics by an order of magnitude more than the other two polymers. The differences in dewetting behaviour correlate with the adsorbed layer characteristics determined by QCM-D. / Thesis (PhD)--University of South Australia, 2010

The hydrophobicity of a surface is an important property in many areas of science and engineering. This is especially the case in mineral processing, where differences in surface hydrophobicity lie at the heart of the separation process of flotation. Chemicals are used to increase and decrease the natural hydrophobicity of minerals to attain a better separation between valuable and worthless material. Polymers are often used to reduce mineral surface hydrophobicity. Decades of empirically based decision making have produced a list of effective depressants. However the detailed study of how these polymer depressants affect surface hydrophobicity and mineral recovery lags behind applied investigations. The aim of this thesis was to study the adsorption of commonly used depressants on model surfaces and to interrogate the action of these polymers in reducing surface hydrophobicity. We have modelled the degree of hydrophobicity of common minerals in order to study polymer depressants with methods not commonly used in studies of surface characterisation in flotation. The model surfaces (self-assembled monolayers, SAMs) allowed us to use the quartz crystal microbalance with dissipation monitoring (QCM-D) to study the adsorption of polymers. The QCM-D can be used to obtain adsorption isotherms, adsorption kinetics, water content of adsorbed layers, and information on the conformation of the adsorbed polymer. The results from the QCM-D were correlated with the contact angle data from the captive bubble measurements, with which we assessed the hydrophobicity of the surface before and after polymer adsorption. Three of the polymers layers were probed with dynamic dewetting studies, in order to test other modes of depressant action. Three types of polymers were studied - a polyacrylamide (Polymer-H), a polyelectrolyte CMC (carboxymethyl cellulose) and a group of dextrins (Dextrin-TY, a phenyl succinate substituted dextrin (PS Dextrin) and a styrene oxide substituted dextrin (SO Dextrin)). These polymers are commonly used or have potential to be used in the depression of talc and graphite. Polymer-H was used to investigate the hydrophobic bonding between a non-ionic polymer depressant and chemically inert and non charged surfaces by probing the influence of substrate hydrophobicity on polymer adsorption and reduction of contact angle. Three different model surfaces were used (mixed self-assembled 0.5 SAM, 0.7 SAM or single self-assembled 1.0 SAM monolayers) with advancing contact angles between 75?? and 119??. The study of Polymer-H found that the substrate hydrophobicity is an important factor in adsorption of this polymer and the change in contact angle upon adsorption depends on adsorbed amount. The effectiveness of Polymer-H to reduce surface hydrophobicity was established to correlate with its conformation and morphology. CMC was investigated to find out how a stimulus responsive polymer depressant can be used in flotation. It was established that the adsorbed amount and rate of adsorption of CMC increase with decreasing of pH or increasing of ionic strength. It was shown that the surface hydrophobicity of a CMC pre-adsorbed layer changes with the environment and these alterations are fully reversible. A switch of ionic strength (from 10-2 M KCl to 10-1 M KCl) caused partial dehydration of the adsorbed layer and a decrease of the receding contact angle by 20??. A pH switch (pH = 9 to pH = 3) resulted in a 40?? change in receding contact angle. The CMC investigation showed that the use of a stimulus responsive polymer presents opportunities for exploiting solution conditions as a means to effect a better mineral separation in flotation The adsorption of three dextrin-based polymers on a model hydrophobic surface has been characterized using the quartz crystal microbalance with dissipation monitoring (QCM-D). The three polymers (one standard dextrin and two dextrins with different aromatic group substitutions) exhibited varying affinities and capacity for adsorption on the hydrophobic substrate. The effect of the three polymers on the static contact angle of the surface was studied using captive bubble contact angle measurements. The three polymers were seen to reduce the receding contact angle by similar amounts (approximately 14 degrees) in spite of having varying adsorbed amounts and differences in adsorbed layer water content. Although no differences were observed in the ability of the polymers to reduce the static contact angle, measurements of the dewetting dynamics between a rising air bubble and the polymer covered substrate yielded stark differences between the polymers, with one polymer slowing the dewetting dynamics by an order of magnitude more than the other two polymers. The differences in dewetting behaviour correlate with the adsorbed layer characteristics determined by QCM-D. / Thesis (PhD)--University of South Australia, 2010

Dendritic spines are fundamental units of information processing within the nervous system, responsible for independent modulation of synaptic input to neurons. Filopodia, often morphologically indistinguishable from spines, are involved in formation of synapses during neuronal development. Despite the importance of these structures for neuronal function, no detailed study of their presence on motoneurons has yet been made. Here, the presence of spines on hypoglossal motoneurons (HMs) is described at three developmental stages: at P0–2 and P9–11, spines are present at an average density of ~0.1 spines/micron, but at P19 spine density becomes negligible. In P0–2 and P9–11, spines are nonuniformly distributed, occuring in clusters, and at lower density in the most proximal and distal regions to the soma than at intermediate regions. HM spines coincide with a decrease in cell input resistance, which reduces excitability during development. Thus one may speculate that these spines are involved in the formation of new synapses required to maintain adequate excitatory drive. A major difficulty for the study of spines is their small size, which complicates measurement using optical methods. Here, I present a novel method for reconstructing spine morphology using geometric models based on a priori knowledge of spine structure. Tests of the technique using simulated data indicate that it has a resolving capability of up to 40 nm (limited by noise). The technique has been used to measure dendritic spines on HMs, showing that these structures have necks as small as 0.22 micron. For purely passive modulation of synaptic strength, spine necks need to be <~ 0.15 micron. These data suggest that if modulation of synaptic input occurs, biochemical and/or active electrical processes are needed. The methods developed in this Thesis, which have here been applied to HMs, are generally applicable to the study of spine morphology, and its effect on synaptic processing, in all classes of neurons.

Dendritic spines are fundamental units of information processing within the nervous system, responsible for independent modulation of synaptic input to neurons. Filopodia, often morphologically indistinguishable from spines, are involved in formation of synapses during neuronal development. Despite the importance of these structures for neuronal function, no detailed study of their presence on motoneurons has yet been made. Here, the presence of spines on hypoglossal motoneurons (HMs) is described at three developmental stages: at P0–2 and P9–11, spines are present at an average density of ~0.1 spines/micron, but at P19 spine density becomes negligible. In P0–2 and P9–11, spines are nonuniformly distributed, occuring in clusters, and at lower density in the most proximal and distal regions to the soma than at intermediate regions. HM spines coincide with a decrease in cell input resistance, which reduces excitability during development. Thus one may speculate that these spines are involved in the formation of new synapses required to maintain adequate excitatory drive. A major difficulty for the study of spines is their small size, which complicates measurement using optical methods. Here, I present a novel method for reconstructing spine morphology using geometric models based on a priori knowledge of spine structure. Tests of the technique using simulated data indicate that it has a resolving capability of up to 40 nm (limited by noise). The technique has been used to measure dendritic spines on HMs, showing that these structures have necks as small as 0.22 micron. For purely passive modulation of synaptic strength, spine necks need to be <~ 0.15 micron. These data suggest that if modulation of synaptic input occurs, biochemical and/or active electrical processes are needed. The methods developed in this Thesis, which have here been applied to HMs, are generally applicable to the study of spine morphology, and its effect on synaptic processing, in all classes of neurons.

Dendritic spines are fundamental units of information processing within the nervous system, responsible for independent modulation of synaptic input to neurons. Filopodia, often morphologically indistinguishable from spines, are involved in formation of synapses during neuronal development. Despite the importance of these structures for neuronal function, no detailed study of their presence on motoneurons has yet been made. Here, the presence of spines on hypoglossal motoneurons (HMs) is described at three developmental stages: at P0–2 and P9–11, spines are present at an average density of ~0.1 spines/micron, but at P19 spine density becomes negligible. In P0–2 and P9–11, spines are nonuniformly distributed, occuring in clusters, and at lower density in the most proximal and distal regions to the soma than at intermediate regions. HM spines coincide with a decrease in cell input resistance, which reduces excitability during development. Thus one may speculate that these spines are involved in the formation of new synapses required to maintain adequate excitatory drive. A major difficulty for the study of spines is their small size, which complicates measurement using optical methods. Here, I present a novel method for reconstructing spine morphology using geometric models based on a priori knowledge of spine structure. Tests of the technique using simulated data indicate that it has a resolving capability of up to 40 nm (limited by noise). The technique has been used to measure dendritic spines on HMs, showing that these structures have necks as small as 0.22 micron. For purely passive modulation of synaptic strength, spine necks need to be <~ 0.15 micron. These data suggest that if modulation of synaptic input occurs, biochemical and/or active electrical processes are needed. The methods developed in this Thesis, which have here been applied to HMs, are generally applicable to the study of spine morphology, and its effect on synaptic processing, in all classes of neurons.

Dendritic spines are fundamental units of information processing within the nervous system, responsible for independent modulation of synaptic input to neurons. Filopodia, often morphologically indistinguishable from spines, are involved in formation of synapses during neuronal development. Despite the importance of these structures for neuronal function, no detailed study of their presence on motoneurons has yet been made. Here, the presence of spines on hypoglossal motoneurons (HMs) is described at three developmental stages: at P0–2 and P9–11, spines are present at an average density of ~0.1 spines/micron, but at P19 spine density becomes negligible. In P0–2 and P9–11, spines are nonuniformly distributed, occuring in clusters, and at lower density in the most proximal and distal regions to the soma than at intermediate regions. HM spines coincide with a decrease in cell input resistance, which reduces excitability during development. Thus one may speculate that these spines are involved in the formation of new synapses required to maintain adequate excitatory drive. A major difficulty for the study of spines is their small size, which complicates measurement using optical methods. Here, I present a novel method for reconstructing spine morphology using geometric models based on a priori knowledge of spine structure. Tests of the technique using simulated data indicate that it has a resolving capability of up to 40 nm (limited by noise). The technique has been used to measure dendritic spines on HMs, showing that these structures have necks as small as 0.22 micron. For purely passive modulation of synaptic strength, spine necks need to be <~ 0.15 micron. These data suggest that if modulation of synaptic input occurs, biochemical and/or active electrical processes are needed. The methods developed in this Thesis, which have here been applied to HMs, are generally applicable to the study of spine morphology, and its effect on synaptic processing, in all classes of neurons.