Substructure dynamics incorporate all features occurring on a subgrain-scale. The substructure governs the rheology of a rock, which in turn determines how it will respond to different processes during tectonic changes. This project details an in-depth study of substructural dynamics during post-deformational annealing, using single-crystal halite as an analogue for silicate materials. The study combines three different techniques; in-situ annealing experiments conducted inside the scanning electron microscope and coupled with electron backscatter diffraction, 3D X-ray diffraction coupled with in-situ heating conducted at the European Radiation Synchrotron Facility and numerical simulation using the microstructural modelling platform Elle. The main outcome of the project is a significantly refined model for recovery at annealing temperatures below that of deformation preceding annealing. Behaviour is highly dependent on the temperature of annealing, particularly related to the activation temperature of climb and is also strongly reliant on short versus long range dislocation effects. Subgrain boundaries were categorised with regard to their behaviour during annealing, orientation and morphology and it was found that different types of boundaries have different behaviour and must be treated as such. Numerical simulation of the recovery process supported these findings, with much of the subgrain boundary behaviour reproduced with small variation to the mobilities on different rotation axes and increase of the size of the calculation area to imitate long-range dislocation effects. Dislocations were found to remain independent to much higher misorientation angles than previously thought, with simulation results indicating that change in boundary response occurs at ~7º for halite. Comparison of 2D experiments to 3D indicated that general boundary behaviour was similar within the volume and was not significantly influenced by effects from the free surface. Boundary migration, however, occurred more extensively in the 3D experiment. This difference is interpreted to be related to boundary drag on thermal grooves on the 2D experimental surface. While relative boundary mobilities will be similar, absolute values must therefore be treated with some care when using a 2D analysis. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

In recent years, interest in using composites with natural fibres as reinforcement and/or filler has increased because of the advantages of natural fibres, such as low density, low cost, high mechanical properties, and biodegradability. Unmodified-hydrophilic natural fibres show poor compatibility with polymer matrix when they are used as reinforcement in polymer composites. <p> Several methods of modifications of natural fibres, such as chemical and plasma modification of natural fibres have been performed to improve the interfacial compatibility of natural fibre and matrix, and also to decrease water absorption of fibres. <p> The purpose of this study was to examine the effect of plasma treatment on Saskatchewan-grown oilseed flax fibre that can be used in biocomposites. For comparison, the fibres have also been chemically modified using sodium hydroxide and silane. A comparison has been made between the results from both cases.<p> In this thesis, both plasma and chemically modified flax fibre are characterized to understand its crystallinity, color changes, mechanical properties, morphological changes, and thermal properties. Techniques such as X-ray diffraction (XRD), color test, tensile test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and soft X - ray spectromicroscopy are used to study the structural changes of flax fibre after physical and chemical modifications. A fitting method with four Gaussian functions was used to determine crystallinity of cellulose. <p> Results showed that the crystallinity of cellulose in modified (physical or chemical) fibres decreased. Chemical treatment did not improve the tensile strength nor the stiffness of the fibres. Morphological studies showed that the fibre surface changes in both treatments were significant, however, the surfaces of flax fibres exposed to the plasma were modified in the near-surface regions. There was no trace of lignin before and after chemical treatment except in the one-hour chemically treated fibres. The color of the fibres became lighter after chemical treatment. Chemical bonding between resin and fibre was observed in the untreated fibres, the one-hour chemically modified fibres and two-hour chemically modified fibres.<p> Results of this research also showed that plasma treatment can be used as a surface modifying method for flax fibres, however there were some restrictions of utilizing the plasma modification method, e.g. sample size and non-uniformity of plasma gas.

Carbon dioxide removal from flue gases of power plants is critical for reduction of greenhouse gas emissions implicated in global warming. Metal Organic Frameworks (MOFs) promising potential applications in carbon dioxide capture due to their unique structural properties such as high porosity and high thermal stability. These MOFs have application in separation processes and gas storage. By the assembly of the organic ligands and metal oxide clusters, porous MOFs can be synthesized. The use of s-block metals such as calcium, magnesium and rubidium in porous materials is appealing because their ionic binding characters with organic ligands will general flexible MOFs. The bonding interaction of s-block metal centers with carboxylate oxygen atoms is mainly ionic in nature due to large differences in electronegativity. The s-block elements can form low density frameworks which could increase the gas uptake capacity of small molecules. This work focuses on synthesis of new metal organic frameworks (MOFs) using s-block metals. Different types of the carboxylic ligands were utilized for synthesis of MOFs. Four new calcium or rubdium metal organic frameworks, [Ca3(btc)2(H2O)12] (1) and [Ca2(btc)(pzc)(H2O)3] (2) (btc=benzene-1,3,5-tricarboxylate, pzc = pyrazine-2- carboxylate), [Ca(Hbtc)(H2O)]•H2O (6), and [Rb(Hbdc)] (7) have been synthesized using the hydro/solvothermal method and have been characterized using X-ray diffraction, IR, UV-vis, TGA and fluorescence analysis. The structures of compounds 1, 6 and 7are three-dimensional frameworks while that of compound 2 is a double layered network.

No description available.

In recent years, interest in using composites with natural fibres as reinforcement and/or filler has increased because of the advantages of natural fibres, such as low density, low cost, high mechanical properties, and biodegradability. Unmodified-hydrophilic natural fibres show poor compatibility with polymer matrix when they are used as reinforcement in polymer composites. <p> Several methods of modifications of natural fibres, such as chemical and plasma modification of natural fibres have been performed to improve the interfacial compatibility of natural fibre and matrix, and also to decrease water absorption of fibres. <p> The purpose of this study was to examine the effect of plasma treatment on Saskatchewan-grown oilseed flax fibre that can be used in biocomposites. For comparison, the fibres have also been chemically modified using sodium hydroxide and silane. A comparison has been made between the results from both cases.<p> In this thesis, both plasma and chemically modified flax fibre are characterized to understand its crystallinity, color changes, mechanical properties, morphological changes, and thermal properties. Techniques such as X-ray diffraction (XRD), color test, tensile test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and soft X - ray spectromicroscopy are used to study the structural changes of flax fibre after physical and chemical modifications. A fitting method with four Gaussian functions was used to determine crystallinity of cellulose. <p> Results showed that the crystallinity of cellulose in modified (physical or chemical) fibres decreased. Chemical treatment did not improve the tensile strength nor the stiffness of the fibres. Morphological studies showed that the fibre surface changes in both treatments were significant, however, the surfaces of flax fibres exposed to the plasma were modified in the near-surface regions. There was no trace of lignin before and after chemical treatment except in the one-hour chemically treated fibres. The color of the fibres became lighter after chemical treatment. Chemical bonding between resin and fibre was observed in the untreated fibres, the one-hour chemically modified fibres and two-hour chemically modified fibres.<p> Results of this research also showed that plasma treatment can be used as a surface modifying method for flax fibres, however there were some restrictions of utilizing the plasma modification method, e.g. sample size and non-uniformity of plasma gas.

The preparation and thermophysical properties of some In(I), Ga(I) and Ag(I) substituted NZP type materials were explored. Many compositions with the NZP framework show low and negative thermal expansion. Previously reported material, GaZr2(PO4(3, transforms from one NZP related phase into another NZP type phase due to oxidation under air above 300oC. In addition, it exhibits hysteresis under inert atmosphere; the cell parameters are different on heating and cooling cycles for a given temperature. The synthesis, and characterization of a new material, InZr2(PO4)3, is outlined. It crystallizes in space group R -3 c. In addition, as GaZr2(PO4)3, it oxidizes above 300oC under air and exhibits hysteresis under inert atmosphere. Furthermore, the synthesis of AgTixZr2-x(PO4)3 solid solution compositions, their ion exchange characteristics with Ga(I) and their thermophysical properties are described. Thermal expansion anisotropy (the difference between a and c ) of the solid solutions decreases as the bigger ion, Zr4+, is substituted by the smaller one, Ti4+. Thermal expansion characteristics of GaZr2(PO4)3, InZr2(PO4)3 and AgZr2(PO4)3 are compared with MZr2(PO4)3 ( M = Li, Na, K, Rb, Cs). Ionic radii for Ga(I) and In(I) in a six coordinate oxygen environment were proposed.

Nitrochemicals are widely used as explosives, biocides and drugs. In addition, 3-nitro-tyrosine and other nitrated protein residues are important markers for many cardiovascular, neurodegenerative, and malignant conditions. Because of the wide presence of the nitrocompounds as toxins, potential nitrogen/carbon sources, and metabolic intermediates, different organisms have evolved to produce enzymes that can biodegrade nitrocompounds. The structural studies of the enzymes, which catalyze the removal of nitro group from nitrochemicals, are of considerable interest for both applied and fundamental reasons. The insights into the reaction mechanism of these enzymes can be used for designing efficient biocatalysts for bioremediation and for developing antibiotics for disease resistant microbes. Nitroalkane oxidase (NAO) produced by

In this paper, polar free-standing (0002)GaN wafer were fabricated by using the hydride vapor phase epitaxy(HVPE) technique on (002) LiGaO2 substrates. Polar of The (0002) GaN affects its luminous efficiency, but compared to other surface between the substrate, it has the smallest lattice mismatch. With the high growth rate of HVPE, hoping to grow high quality GaN thick layer. In the self-designed reactor, Metallic gallium and NH3 were the source of Ga and N. Nitrogen and hydrogen were used as the carrier gases HCl and nitrogen was designed to pass through liquid Ga to form GaCl fully. GaN deposition was realized Efficaciously by conducted steady NH3 and GaCl flows to the substrate suface, accommodated with additional hydrogen and nitrogen atmosphere flows.The parameters set of research mainly focus on reaction pressure, temperature, and growth time. In order to obtain better crystal quality, more attempts were made to grow buffer layer by chemical vapor deposition first, then a thick GaN layer by HVPE. The next step is to do the experiment and analyze with various instruments. Scanning Electron Microscope and atomic force microscopy Atomic Force Microscpoic are used to observe the surface morphology. X-ray Diffracion and transmission electron microscopy are used to know the lattice structure, and to understand the interface between the substrate and the GaN film crystal structure and epitaxial relationship. Finally, Photoluminescence spectroscopy is used to measure its optical properties and compare its defects and epitaxial quality.

The group III nitride semiconductor grown on c-plane sapphire by radio frequency plasma assisted molecular beam epitaxy has been studied. To archive good quality GaN film, nitridation and low temperature buffer layer were applied to overcome the issue of lattice mismatch. Low temperature and long period nitridation process shows better improved of optical properties and crystal quality of GaN film. Buffer layer grown with slightly Ga-rich, substrate temperature at 522¢J, for 2 minutes leads to better GaN film. High substrate temperature and sufficient nitrogen to gallium ratio are two important factors to control the growth of the good quality GaN epilayer. Chemical etching and observation of surface reconstructions were used to characterize the polarity of group III nitrides. The Ga-polarity GaN film shows 2x surface reconstruction with high chemical resistance while the N-polarity is sensitive to chemical and displays the 3x reconstruction pattern. The process of indium incorporated with GaN is very sensitive to growth temperature. The indium content decreased with increasing the substrate temperature and also decreased along the growth direction. The N-polar GaN with an indium-facilitated growth technique was also studied. Upon the incorporation of indium during growth, the photoluminescence intensity and electron mobility of GaN has been enhanced by a factor of 15 and 6 respectively. The electron concentration drastically increases by several orders of magnitude. The biaxial strain of GaN film estimated with Micro-Raman technique reduces from 0.6729 to 0.5044GPa. The full-widths at half maximum of asymmetric (10-12) x-ray reflection which related to the density of overall threading dislocations increases from 593 to744 arcsec. In contrast, the symmetric (0002) reflection related only to threading dislocations having a non-zero c-component Burgers vectors reduces from 528 to 276 arcsec. The enhancement of GaN optical property is generally attributed to the reduction of non-zero c-component dislocations. The reduction in density is confirmed by cross-sectional transmission electron microscopy.

Composite propellants are mainly composed of: crystalline oxidizer, metallic fuel, and polymeric binder. Additives, such as plasticizers, catalysts, bonding agents and curing agents may also be incorporated to propellant compositions in small amounts. These ingredients should be mixed rigorously in order to obtain a uniform microstructure throughout the cast propellant profile. The quality of the propellant mixture has to be determined quantitatively to improve the product quality and to reduce costs. In this study, it was aimed to develop an easy, cost effective and rapid test method for determining the optimum mixing conditions for the manufacturing process of solid rocket propellants. An analytical method used in the literature for assessing mixing quality in highly filled polymeric systems is wide-angle x-ray diffractometry (WA-XRD). After finding out the concentration distribution of the components indirectly by WA-XRD, degree of mixing was identified using statistical methods. To accomplish this, series of samples were taken from various locations of the mixing chamber and analyzed by WA-XRD. Degree of mixing calculations based on ratio of intensity arising from aluminum phase over total crystal intensity, and the ratio of intensity arising from ammonium perchlorate phase over total crystal intensity gave satisfactory results. Radial mixing efficiency of planetary mixer was determined, and it was found that mixing at the center was more effective than mixing at the outer regions. Also, by scanning electron microscopy technique (SEM), interactions between binder and solid loading during mixing process were observed. It was seen that polymeric matrix gradually encloses solid particles during mixing.