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Because the deep Earth is not directly accessible, geoscientists rely on laboratory experiments and computer models in order to understand the properties of minerals at the extreme pressure and temperature conditions of deep crust, the mantle and the core. In the field of high-pressure mineral physics and chemistry, we use our understanding of mineral properties, stress–strain relationships in multiphase rocks, and processes such as partial melting at high pressures and temperatures, to interpret geophysical observations of the deep Earth. Studies have constrained the pressure sensitivity of deformation of minerals such as olivine under subduction zone conditions, and the effect of pressure on slip systems in high-pressure minerals such as wadsleyite and perovskite. These results have important implications for the variation of mantle viscosity with depth, the geodynamic interpretation of seismic anisotropy, and changes in mantle rheology as a function of composition. However, the rheology and dynamics of the deep Earth are still poorly understood. Fortunately, technical development has been undertaken over the past 10 years in the USA, and scientific advances have been helped by the development of high-P–T deformation apparatus, such as the large volume multi-anvil deformation apparatus known as the D-DIA. This has opened up the possibility of determining physical and chemical processes in the upper mantle, and into the mantle transition zone. To participate in this exciting new area of research, we are now developing a high-pressure facility at the Australian Synchrotron. In this overview paper, we describe the background and current research that is being conducted in other synchrotron high-pressure facilities and what will now be possible for the Australian Synchrotron. [ABSTRACT FROM PUBLISHER]

Crisp expanded wafers were produced from extruded pellets containing specialty starches and flours derived from peas, lentils, corn and blends of lentils and corn. The density, hardness and consumer acceptability of the wafers varied with the different ingredients. The most acceptable products were produced from corn, lentils and blends of these two ingredients. The weight, density, stiffness and hardness of the wafers increased with the proportion of lentil flour used to make them. Sensory analysis suggested that consumer acceptability was optimal for blends containing between 40 and 80% of lentil flour. Stiffness and fracture force measured by texture profile analysis were correlated with the sensory attributes of hardness and toughness. The glycemic potential measured by in vitro digestion of the wafers was lower for the 100% lentil wafers compared with the 100% corn wafers because of the amount of starch in the grain. For combinations of corn and lentils, the carbohydrate digestion rate, and hence the glycemic potential, was lower than for either 100% corn or 100% lentil wafers. Blending of selected cereal flour ingredients should be a useful method for reducing the glycemic impact of cooked starchy snacks. [ABSTRACT FROM AUTHOR]

A host of fascinating and useful magnetic phenomena are found in composites containing magnetizable particles in viscoelastic solids. Embedding magnetically soft iron particles in natural rubber produces a class of magnetostrictive composites sometimes termed magnetorheological (MR) elastomers. We have previously shown that these materials can exhibit viscoelastic moduli that increase substantially in an applied magnetic field. In this paper, we incorporate MR elastomers in a simple resonant structure called a tuned vibration absorber to measure the complex dynamic shear moduli of these materials at high frequencies. We find that the field-induced modulus increase in MR elastomers is substantial even at kilohertz mechanical frequencies. As in previous measurements at low frequencies, the moduli are generally found to decrease with strain amplitude. We also report preliminary measurements of the relatively large elongation of these materials in applied magnetic fields. [ABSTRACT FROM AUTHOR]