Information on the density of hydrocarbons at high pressures and temperatures is of great importance in many fields, such as the study of ultra-deep reservoirs up to ~240 MPa and 250°C. However, density data at such high pressures and temperatures are often not available in the literature. In this study, experimental densities are reported for n-pentane, n-octane, 2,2,4-trimethylpentane, cyclooctane, n-decane, and toluene to ~280 MPa and ~250°C. These experimental densities are in good agreement with available literature data, although the literature data for many of these fluids do not extend to the pressures and temperatures utilized in this study.

Metal oxides containing ruthenium have a surprisingly varied range of low-temperature physical properties including the superconductor Sr2RuO4 and the metallic ferromagnet SrRuO3. The exceptionally broad manifold of itinerate and localised electronic phenomena is derived from broad Ru 4d bands and a wide number of Ru and O containing crystallographic structures. High-pressure is a powerful tool for manipulating crystal structures and tuning the associated electronic and magnetic properties. In this body of work, pressure has been utilised in two roles for the study of ternary ruthenates with perovskite and pyrochlore structures; as a synthetic method and for in situ studies (crystallographic or physical) of existing compounds. Chapter 3 details pressure dependent changes in the crystal structure of the perovskite PbRuO3 by powder x-ray diffraction up to 46 GPa and down to 20 K. PbRuO3 transformed on cooling, from orthorhombic spacegroup (Pnma) to an orbitally ordered low temperature phase, which is also an orthorhombic space group (Imma) and applied pressure reduced the critical temperature totally inhibiting the transition at 5.5 GPa. Additionally PbRuO3 was found to undergo a reversible pressure induced structural phase transition at 30 GPa and 290 K with a 10 % reduction in unit-cell volume. Indexing indicated an orthorhombic symmetry with a Pnna spacegroup. Pnna is not a spacegroup associated with perovskite or related perovskite structures despite the √2 x 2 x √2 perovskite superstructure being maintained across the transition. high-pressure resistivity and Raman measurements indicated that a metal-insulator transition accompanied the structural transition. In Chapter 4 high-pressure high-temperature (HP-HT) synthesis has been used to isolate dense phases that could not be produced at ambient pressure. The ortho-perovskite LaRuO3 with space group Pnma (# 62) was synthesised by conventional solid state methods. However to extend the series by substituting the smaller rare-earth cations, Ln3+ on the A-site of the same perovskite structure HP-HT (10 GPa and 1200° C) conditions were required. A powder diffraction study confirmed the Pnma structure of LnRuO3 where, Ln = Pr, Nd, Sm, Eu, Gd, Dy and Ho, of which the later rare-earth compounds, where Ln = Sm to Ho have not been synthesised before. Neutron powder diffraction studies of LnRuO3 where Ln = La, Pr and Nd down to 7 K suggests a ~ 10 % non-stoichiometry on the Ru site, leading to the adjusted formula LnRu0.9O3 with an unusually low Ru3.3+ valency. A possible exception to the low Ru oxidation state is EuRuO3, which has a larger unit-cell, suggesting a Eu2+Ru4+O3 charge distribution with the more common Ru4+, however, this is not concordant with magnetisation measurements. Additionally neutron diffraction suggests that the RuO6 octahedra are distorted by spin-orbit coupling. Magnetometry and resistivity measurements indicate that the compounds are semiconducting paramagnets down to 7 K. Finally in Chapter 5 is presented the analysis of a high-pressure powder x-ray diffraction experiment of the pyrochlore Tl2Ru2O7. Carried out at synchrotron facilities, we have extended the pressure-temperature phase diagram to 3.7 GPa and 25 K. Previously it had been reported that, when cooled, Tl2Ru2O7 undergoes a structural phase transition from a cubic (Fd-3m) phase to a low temperature, orthorhombic (Pnma) phase that forms Haldane chains - an unusual one-dimensional orbital ordering. As for PbRuO3 high-pressure conditions are found to inhibit the orbital ordering, to reduce the critical temperature and to suppress the transition at pressures exceeding 3.0 GPa.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisors: Suresh G. Advani, Dept. of Mechanical Engineering, and Eric D. Wetzel, Army Research Laboratory. Includes bibliographical references.

The traditional way of processing milk is the application of heat to destroy undesirable microorganisms. Though heat is an effective means of doing the job, it is associated with several limitations. High pressure (HP) processing has the potential for eliminating microorganisms without affecting the natural quality of the raw material. As a result, it has become a promising technique in recent years. Many factors are reported to influence HP destruction of microorganisms, the most important ones include food composition (i.e., lipid, carbohydrate and protein contents), water activity, process temperature, and mode of pressure treatment. Therefore, the objectives of this research were to: (a) evaluate the effect of milk composition on destruction of E. coli by HP, (b) evaluate kinetic models for spoilage and pathogenic microorganism in milk and the effect of different pressure mode (pulse and static) on the destruction rates; and (c) to evaluate the effect of milk type (UHT and raw milk) and temperate on destruction of microorganism.

Two classes of parameters are important in product quality control and process design: thermo-physical and rheological properties. Reliable estimates of thermal properties (thermal conductivity, diffusivity, density, specific heat, and glass transition temperature) are needed to model the rate of heat transfer during food processing. Measurements of rheological parameters like viscosity and elasticity have been recognized as important tools to provide fundamental insights on structural organization of the food. Small amplitude oscillatory testing is useful in evaluation of gel characteristics and texture development in different food products. Proper design of industrial plants, modeling and automation in food process industry require data on these properties for better quality control and improve the shelf life. Thermal processing has been a traditionally accepted method for developing safe and shelf-stable products. However, a disadvantage of thermal treatment is the reduced sensory and nutritional qualities. High pressure (HP) treatment, a novel non-thermal preservation technique, is used for producing high quality products. HP processing can also be used to achieve products with better textural properties and improved nutrition when supplemented with proteins. / This research was carried out in two parts. In first part, experiments with mango pulp were carried out at four temperatures (20, 40, 60 and 80°C) and total soluble solids concentrations (15, 20, 30 and 40°Brix) and their rheological and thermo-physical properties were evaluated and modeled. Thermal properties of mango puree were primarily dependent on the moisture content of the sample, and increased with temperature and decreased with concentration. Density showed a reverse trend. Glass transition temperatures increased with an increase in concentration indicating better stability. Separate models were developed for each thermal property as a function of temperature and concentration (R2 >0.90). Mango puree exhibited pseudoplaticity during steady shear measurements, and the power law model well described their flow behavior. Consistency coefficient increased with concentration and decreased with temperature. The flow behavior index decreased with concentration and generally increased with temperature beyond 40°C. Dynamic oscillation shear measurements revealed that mango puree behaved like a weak gel and demonstrated visco-elastic properties. / In the second part, experiments were divided in to two parts. In first part, the original soluble solids in mango puree (28°Brix) was lowered to 20, 23 and 26°Brix and each was supplemented with 2, 5 and 8% of whey protein. Effect of HP treatment at 425, 500, and 575 MPa with 0, 3 and 6 min holding times on rheological properties were evaluated. Pressure treatment resulted in a positive effect on elastic (G') and viscous modulii (G") as well as complex viscosity (eta*). Values of G' were higher than G" demonstrating the product to behave more and more like a gel. The changes in rheological parameters at 500 MPa were modeled based on soluble solids and protein content. In the second part of the experiments, the protein (P) and soluble solids concentrations (S) were simultaneously varied maintaining a total solids content at 28% (same as in the original mango puree) and their combined influence (P/S: 2/26, 3/25, 5/23, 7/21 and 8/20) on the rheology of the product after selected HP treatments (425-575 MPa, 0-6 min) were evaluated. The effects of holding time and pressure level were similar to those observed previously in first part of this study. However, the positive effect of added protein was over dominated by negative effect of the simultaneous decrease in the soluble solids concentration, resulting in an overall decreasing effect as protein content increased (with a same magnitude decrease in soluble solids content). Developed models well predicted the combined influence of protein and soluble solids concentration on rheological parameters (R2>0.85). / Sensory evaluation of mango puree supplemented with protein (2, 5 and 8%) was performed before and after high pressure treatment (500MPa/3min) using a nine point hedonic scale. The quality parameters chosen were color, sweetness, mouthfeel, flavor and acceptability. Sensory evaluation results indicated that protein enrichment up to 5% level did not adversely affect the sensory qualities.

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No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University. / Vita. Abstract. Includes bibliographical references (leaves 130-136). Also available via the Internet.

Thesis (M.Eng.Sc) - University of Queensland, / Includes bibliography.

Neutron diffraction is an extremely powerful technique in condensed matter research; it can be used to measure crystallographic structures, including some of those undeterminable using X-rays. It is also perhaps the most powerful technique for determining magnetic structures, and for probing the strength of magnetic interactions, revealing information beyond that extractable from a magnetometer. High pressure is used by many condensed matter researchers as an additional thermodynamic variable, or tool to perturb otherwise stable systems, and has been used with neutron diffraction for many years. When coupled with low temperatures, this has led to the discovery of an enormous range of non-ambient phases of matter, with a range of exotic properties, some of which are discussed in this thesis. Pressure has a very strong effect on the magnetic properties of a material, with many of the most unusual magnetic phases existing only at extremely low temperatures, or pressures which can only be reached on very small samples. The main topic for this thesis is the study, development, and implementation of new techniques to combine low temperatures, high pressures, and neutron diffraction measurements from micro sized samples. A new pressure cell has been designed, tested, and commissioned with neutron beam time on the WISH diffractometer at the ISIS neutron facility. The cell is compact, with a total mass of approximately 5 kg, and is capable of generating large loads in excess of 4.5 tonnes force. Depending on the sample size used with the cell, the opposed anvil system is capable of generating a range of different pressures beyond what is widely available for low temperature neutron diffraction measurements. To save wasted experimental time in cooling and warming the device, the cell is capable of varying the applied load continuously down to 5 K, whilst the sample pressure can also be measured in-situ using a compact spectrometer system. Obtaining refineable neutron diffraction data from the small samples (< 1mm3) possible in an opposed anvil pressure cell is challenging due to extremely low ratios of signal-to-background when compared with large volume pressure cells. Finite element analysis (FEA) was performed to minimise the mass of the cell, whilst also minimising the amount of supporting material in the beam. Despite this, the signal from the sample is typically very weak; to overcome this, a novel 3D printed device has been designed and tested to collimate extremely small samples, removing much of the background signal from the surrounding material. It has enabled neutron data to be collected from samples an order of magnitude smaller than previously measurable in the cell. To maximise the pressures achievable in the pressure cell, for a given sample volume, an extended FEA study was performed to understand the evolutions of stresses in the cell, and understand the limitations of using sapphire as an anvil material. To complement this work, a compact piston cylinder cell has also been designed for a combination of different measurements. One of the key challenges in high pressure research is in knowing, or ensuring, that the conditions the sample is under are approximately the same for a variety of different measurements. Since different instruments, and techniques, may not allow for the same apparatus to be used between them, this is not always possible. A compact clamped piston cylinder cell has been designed, suitable for in-situ electrical measurements, with additional potential for simultaneous neutron diffraction measurements. The device is demonstrated through an ultrasonic characterisation of the compound UGe2. In addition to the information obtainable from neutron diffraction, much can be learnt from studying the transport properties of a material. This information can be used alongside neutron data to provide a full understanding of how a material behaves. One technique of interest measures how the electrical properties of a material changes under applied magnetic field. This is difficult to achieve under pressure due to the often anisotropic construction of the pressure cell affecting the magnetic field on the sample in different orientations, and the challenge in getting wires to the sample under pressure. This thesis presents the design, and preliminary testing, of an ultra compact high symmetry piston cylinder cell designed to be taken to sub-Kelvin temperatures and rotationally oriented in applied magnetic field. The spherical construction of the cell means that the field on the sample position is, to a very close approximation, identical in all orientations. Finally, this thesis presents a study of the binary alloy Pd3Fe under pressure. Pd3Fe was recently reported to undergo a large-volume collapse under high pressure at room temperature, resulting in near zero thermal expansion]. There are several competing theories on the mechanism behind this process. To investigate further, a series of single crystal Pd3Fe samples were grown, cut, prepared, and extensively analysed. The results of this study suggest that the cause for the large volume collapse may not be magnetic in nature, as previously expected.