The first goal of this thesis is to validate a detailed co-flow flame soot formation model for high pressure applications. The second goal is to use this detailed model to understand the effect pressure has on soot formation. The third goal is to note any deficiencies in the model, and the fourth is to remedy these issues. The thesis is divided into two research studies. The first study validates the model for high pressure use against ethane-air co-flow diffusion flames from 2 to 15 atm. After validation, the results are used to determine the impact pressure has on the three main soot formation processes. It is determined that the original model could not account for the flame pre-heating effect. The second study addresses this issue by adapting the model to extend below the fuel tube exit plane, and includes conjugate heat transfer (CHT) between the fluid streams and solid fuel tube.

Common brown colour in natural diamond forms by plastic deformation during storage in the subcontinental lithospheric mantle (SCLM). Dislocation movement generates vacancies, which aggregate into clusters of perhaps 30–60 vacancies. Positron annihilation lifetime spectroscopy (PALS) and electron energy loss spectroscopy (EELS) support such vacancy clusters as the cause of brown colour. Brief treatment in a high-pressure–high-temperature (HPHT) vessel at 1800–2700 °C can destroy the brown colour. There has been speculation that similar colour removal should occur continuously at depth in the SCLM. Diamonds are stored at 900–1400 °C in the SCLM, according to inclusion thermometry. The effect of temperature on the time required to destroy brown colour has been calculated from published data. The activation energy for the breakup of vacancy clusters is a critical component. The time required to destroy brown colour in the SCLM is significant at the scale of geological time. Brown diamonds should easily maintain their colour for millions of years during cooler mantle storage at or below about 1000 °C. Warmer temperatures toward the base of the lithosphere may be able to reduce or eliminate brown colour within thousands of years. The survival of brown colour in the lithospheric mantle does not require the colour to be formed late in the storage history nor does it require metastable storage in the graphite stability field. Crystal strain is preserved upon loss of brown colour during HPHT treatment. Inhomogeneous crystal strain was measured in 18 natural diamonds using micro-X-ray diffraction (μXRD) χ-dimension peak widths. There is a correlation between strain and depth of brown colour. None of the colourless diamonds examined have high strain, as should be expected for a diamond that has gained and lost brown colour. This suggests that removal of brown colour is not a common natural occurrence. Infrared spectroscopy was used to determine nitrogen concentration and aggregation state in 60 natural diamonds. A loose association was found between brown colour and lower total nitrogen content. Within single diamonds, regions with less nitrogen tend to exhibit more anomalous birefringence due to strain. Colour zoned diamonds tend to have less nitrogen in the darker brown regions. This supports the hypothesis that diamonds with less nitrogen are more susceptible to plastic deformation and the development of brown colour. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2009-09-17 17:10:11.078

The application of high pressure (HP) processing on trout and shrimps was investigated in order to study its effect on their quality attributes. Five levels of pressure, holding time and temperature were selected using a central composite rotatable design (CCRD), the central point being. 200 MPa, 30 min and 10°C. This design was used in order to permit the measurement and modeling of changes in various quality parameters as a result of changes in the process variables. The color parameters (L*, a*, and b* values), physical attributes (drip-loss, protein leaching and water holding capacity) and texture parameters (firmness and springiness) in each case were evaluated, and modeled as second order polynomial equations. / Artificial Neural Network modeling was employed to investigate its ability in predicting the quality changes in both pressure-treated trout fillets and shrimp samples, and its performance was with statistical models. / High pressure (HP) kinetics of the microbial destruction in both trout and shrimp was also studied. (Abstract shortened by UMI.)

High pressure (HP) processing, a novel technology, has excellent potential for non-thermal preservation of apple juice, the largest consumed fruit juice in North America. The objective of this research was to evaluate the application of HP treatment for inactivation of enzymes and destruction of microorganisms in apple juice. HP inactivation kinetics of selected enzymes (amylase, pectin methyl esterase and polyphenol oxidase) and microorganisms [Leuconostoc mesenteroides, Pichia membranaefaciens and Zygosaccharomyces badii, Escherichia coli (29055) and Escherichia coli (O157:H7)] in apple juice were evaluated under various test conditions (100--400 MPa, 0--60 min and 6--40°C) using a central composite design of experiments. The enzymes selected were of importance in apple juice preparation and/or storage stability of the processed juice. Microorganisms included those that are responsible for spoilage and/or public health concern as well as those that are indicative of unsanitary handling conditions. / Enzyme inactivation and microbial destruction due to pressure followed a dual-effect model consisting of a pressure pulse effect (PE) and a subsequent semi-logarithmic (first order) inactivation during the pressure hold-time. In general, results showed that inactivation of enzymes and destruction of microorganisms was more prominent at higher-pressure levels, higher temperature and longer treatment times, and at lower pH levels of juice. Pressure pulse effect was dependent on pressure level, with higher PE achieved at higher pressures. During the pressure-hold, as expected, the associated decimal reduction times (D values) decreased with an increase in pressure. Pressure dependency of D values was well described by the conventional death time model. The pressure resistance of enzymes and microorganisms varied, but complete inactivation of enzymes and destruction of microorganisms was possible with the combination of lower pH, higher pressure and higher temperatures. / Commercial PME from a citrus source was more pressure sensitive than PME from microbial source. Spoilage bacteria (L. mesenteroides) were more pressure resistant than the yeasts. E. coli enumerated on an enrichment media (supporting both injured and healthy cells) showed larger survivors and a greater resistance than on a more selective media. An increasing number of cells got injured than killed with the application of pressure treatment until they were all finally injured or killed. High-pressure treatment (pulse at 400 MPa or by holding about 10 min at 350 MPa and 30°C) resulted in complete destruction of the pathogenic microorganism E. coli (O157:H7) ensuring the public health safety of the process.

Hydrostatic pressure has been demonstrated to induce major changes in secondary structure of whey proteins resulting in an increased digestibility in vitro, and possibly an improvement of the glutathione (GSH) inducing effect of whey proteins in vivo. Micro filtration and ion-exchange, two commonly used processing techniques in whey protein manufacture, generate whey proteins with different compositions. Two animal studies were designed to compare the digestibility and GSH inducing effects of whey protein isolates (WPIs) treated with three repeated pulse cycling of pressure (3-cycle) or single pulse of high pressure (1-cycle) and pressurized microfiltrated and ion-exchange WPIs. The results indicate that special hydrostatic pressure treatment on the proteins improves its growth stimulating effect, but does not enhance the GSH-inducing effect of WPI in the healthy growing rats. Difference among commercial whey protein products is also an important factor that affects the biological properties of the pressurized whey proteins. In conclusion, both proper pressure treatment and product composition should be considered in order to find the most bio-effective whey protein preparation.

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