This thesis will introduce the study of methane as a mineral. Along with ammonia and water, methane is one of the main planetary-forming materials in the outer solar system. The topic of `new mineralogy of the outer solar system' is outlined and introduced, and previous studies in the area are discussed. This review identities a lack of highpressure structural knowledge on methane when compared to ammonia and water. The significance of this knowledge for the study of the planets Neptune and Uranus is discussed. The crystal structures of methane above 5.2 GPa were, prior to this thesis, unknown. To tackle this long-standing problem an integrated approach of high-pressure diffraction techniques had to be used. The dominance of hydrogen within the structures of methane necessitated the use of neutron diffraction. The difficulties and limitations of highpressure neutron powder diffraction are presented. It will be shown that the complexity of the subsequent structures required the use of single-crystal x-ray diffraction. Using a combination of x-ray and neutron diffraction the structures of methane phase A (5.2 - 10 GPa) and B (10 - 25 GPa) were solved. The structure of phase A, was shown to conform to an indexing from literature [Nakahata 99] of a rhombohedral unit cell with α ≈ 89.3° and a ≈ 8.6 Å. Powder data were insufficient to determine atomic positions for this phase, and a single-crystal xray diffraction study was undertaken. The process of growing samples for this study is described as well as data collection. As a result of these studies the carbon atoms were located within methane phase A, and the density of the structure confined. The heavy atom structure, of phase A, was refined against neutron powder diffraction data, enabling positions of hydrogen atoms to be found. Preliminary powder diffraction studies of methane phase B found that the structure did not conform to the unit cell described within the literature. The phase was instead assigned to a cubic unit cell with a ≈ 11.73 Å. Similarly to the studies of phase A, a single-crystal x-ray diffraction study was undertaken. This was complicated by the presence of a contaminant within the sample area. This contaminant was shown to have no effect on the structural results. From a single-crystal study the heavy atom structure of phase B was found. The thesis charts the attempt, but ultimate failure, to obtain neutron powder diffraction on this phase. Comparisons of phase B with the higher pressure phase HP (25 GPa +) led to the conclusion that there would still be some disorder within the hydrogen atoms of phase B. Other studies have been carried out on the methane phase diagram. A Raman spectroscopy study, in the literature, on the low-temperature and high-pressure region of the phase diagrams (20 K up to 30 GPa) had suggested the existence of 3 additional phases of methane. A low-temperature, high-pressure neutron diffraction experiment was undertaken to try and characterise these phases. It was found that the phase A structure persisted under all conditions (to 20 K and 5 GPa) throwing the original results into question. During the growth of single-crystals for the above studies on phase A and B, a high-temperature solid-solid phase transition was observed. This transition line was mapped out and the phase resulting from it characterised with high-temperature single-crystal x-ray diffraction.

Recent studies have demonstrated that applied hydrostatic pressure can affect the functional properties of whey protein isolate (WPI). In this work, the effects of applied hydrostatic pressure on the tertiary and secondary structure of whey proteins were investigated by spectroscopic and rheological techniques to elucidate the molecular basis of such pressure-induced changes in protein functionality. The individual protein components of WPI and various samples of WPI obtained from different sources were subjected to different single-cycle pressure treatments of up to 400 MPa in 100 MPa increments with 30-min holding time as well as to pressures ranging from 450 to 650 MPa without a holding time. Electrospray ionization-mass spectrometry, circular dichroism, and Fourier transform Raman spectroscopic studies of pressure-treated samples of beta-lactoglobulin, the major protein component of WPI, revealed significant changes in tertiary structure. Fourier transform infrared spectroscopic studies revealed that the secondary structure of beta-lactoglobulin was also sensitive to applied pressure and holding time. The secondary and tertiary structure of alpha-lactalbumin, the second most prevalent protein in WPI, was unaffected by applied hydrostatic pressure. The spectroscopic behaviour of the various samples of WPI subjected to pressure treatment was variable and indicated that the response of WPI to applied hydrostatic pressure is dependent on the method used to isolate the WPI from whey. The rheological profiles of beta-lactoglobulin, alpha-lactalbumin, and WPI samples after various pressure treatments were also recorded. Both beta-lactoglobulin and WPI exhibited marked increases in viscosity with increasing pressure, whereas alpha-lactalbumin remained solutions exhibited no significant change in viscosity. These studies have furthered the understanding of the effects of applied hydrostatic pressure on the molecular structure and rheological pr

Accurate determination of soot emissions from combustion is of interest in both fundamental research and industries that rely on combustion. Laser-induced incandescence of soot particles is a young technique that allows unobtrusive measurements of both soot volume fraction and particulate size. An apparatus utilizing this technique has been brought to function for both atmospheric and high pressure measurements. Proof of concept measurements of an atmospheric ethylene-air laminar diffusion flame at 35, 42, and 47 mm above the burner exit correlate well with literature findings. Profile trends of a methane-air diffusion flame at 10, 20, and 40 atm at 6 mm above the burner are similar to reports in literature and are compared to trends from spectral soot emission measurements. Particle size is found to be roughly proportional to pressure. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus are herein.

An experimental study was conducted using axisymmetric co-flow laminar diffusion flames of methane-air, methane-oxygen and ethylene-air to examine the effect of pressure on soot formation and the structure of the temperature field. A liquid fuel burner was designed and built to observe the sooting behavior of methanol-air and n-heptane-air laminar diffusion flames at elevated pressures up to 50 atm. A non-intrusive, line-of-sight spectral soot emission (SSE) diagnostic technique was used to determine the temperature and the soot volume fraction of methane-air flames up to 60 atm, methane-oxygen flames up to 90 atm and ethylene-air flames up to 35 atm. The physical flame structure of the methane-air and methane-oxygen diffusion flames were characterized over the pressure range of 10 to 100 atm and up to 35 atm for ethylene-air flames. The flame height, marked by the visible soot radiation emission, remained relatively constant for methane-air and ethylene-air flames over their respected pressure ranges, while the visible flame height for the methane-oxygen flames was reduced by over 50 % between 10 and 100 atm. During methane-air experiments, observations of anomalous occurrence of liquid material formation at 60 atm and above were recorded. The maximum conversion of the carbon in the fuel to soot exhibited a strong power-law dependence on pressure. At pressures 10 to 30 atm, the pressure exponent is approximately 0.73 for methane-air flames. At higher pressures, between 30 and 60 atm, the pressure exponent is approximately 0.33. The maximum fuel carbon conversion to soot is 12.6 % at 60 atm. For methane-oxygen flames, the pressure exponent is approximately 1.2 for pressures between 10 and 40 atm. At pressures between 50 and 70 atm, the pressure exponent is about -3.8 and approximately -12 for 70 to 90 atm. The maximum fuel carbon conversion to soot is 2 % at 40 atm. For ethylene-air flames, the pressure exponent is approximately 1.4 between 10 and 30 atm. The maximum carbon conversion to soot is approximately 6.5 % at 30 atm and remained constant at higher pressures.

Accurate determination of soot emissions from combustion is of interest in both fundamental research and industries that rely on combustion. Laser-induced incandescence of soot particles is a young technique that allows unobtrusive measurements of both soot volume fraction and particulate size. An apparatus utilizing this technique has been brought to function for both atmospheric and high pressure measurements. Proof of concept measurements of an atmospheric ethylene-air laminar diffusion flame at 35, 42, and 47 mm above the burner exit correlate well with literature findings. Profile trends of a methane-air diffusion flame at 10, 20, and 40 atm at 6 mm above the burner are similar to reports in literature and are compared to trends from spectral soot emission measurements. Particle size is found to be roughly proportional to pressure. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus are herein.

Fuel flexibility in gas turbines is of particular importance because of the main fuel source, natural gas. Blends of methane, ethane, and propane are big constituents in natural gas and consequently are of particular interest. With this level of importance comes the need for baseline data such as laminar flame speed of said fuels. While flame speeds at standard temperature and pressure have been extensively studied in the literature, experimental data at turbine-like conditions are still lacking currently. This thesis discusses the theory behind laminar flames; new data acquisition techniques; temperature and pressure capability improvements; measured flame speeds; and a discussion of the results including stability analysis. The measured flame speeds were those of methane, ethane, and propane fuel blends, as well as pure methane, at an elevated pressure of 5 atm and temperatures of 298 and 473 K, using a constant-volume, cylindrical combustion vessel. The current Aramco mechanism developed in conjunction with National University of Ireland Galway compared favorably with the data, while the literature data showed discrepancies at stoichiometric to rich conditions. An in-depth flame speed uncertainty analysis yielded a wide range of values from 0.5 cm/s to 21.5 cm/s. It is well known that high-pressure experiments develop flame instabilities when air is used as the oxidizer. In this study, the hydrodynamic instabilities were restrained by using a high diluent-to-oxygen ratio. The thermal-diffusive instabilities were inhibited by using helium as the diluent. To characterize this flame stability, the Markstein length and Lewis number were calculated for the presented conditions. The resultant positive Markstein lengths showed a low propensity of flame speed to flame stretch, while the larger-than-unity Lewis numbers showed the relatively higher diffusivity of helium to that of nitrogen.

Thermal processing is the primary mode of preservation of mango products, which can be considerably damaging to the delicate quality of mango. HP processing could thus be a potential alternative for extending the shelf-life of mango products. Establishing HP processing technology need data on microbial inactivation kinetics and shelf-life study of the product. The objective of this research was therefore to evaluate the application of HP treatment for inactivation of microorganisms (pathogenic and spoilage type) and to evaluate the shelf-life of HP treated mango juice. / HP destruction kinetics of three common spoilage microorganisms, Leuconostoc mesenteroides, Zygosaccharomyces bailii and Pichia membranaefaciens and two pathogenic microorganisms, Escherichia coli O157:H7 and Listeria monocytogenes Scott A, were evaluated at 250-550 MPa with 0-60 min holding time at room temperature with species specific initial counts between 10 6 to 108 CFU/mL.

Bibliography: leaves 213-223. / xv, 223 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis examines the cell-fluid interactions that occur during homogenization and combines them with an investigation of the mechanical properties of the cell. This results in a predictive model for cell-disruption efficiency during high-pressure homogenization. The mechanical properties of individual cells are characterised using a micro-manipulation technique. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1997

Thesis (Ph.D.)--University of Tulsa, 1975. / Bibliography: leaves 35-36.

Thesis (Ph.D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 136-142).