Particles Confined by Fluid Interfaces: Imaging Particle Motion, Interface Deformation and Capillary Forces

Small solid particles, confined in two-dimensions by fluid interfaces, were studied by a variety of experimental methods to understand particle motion, menisci shapes near interface-supported particles, and capillary interactions among such particles. Unwanted evaporation was circumvented by adopting non-volatile ionic liquids to create the fluid interfaces. A related application, employment of ionic liquids to float cryo-microtomed polymer sections, was also developed. The Brownian motions of nanospheres and nanorods in free-standing ionic liquid films were visualized in situ by high resolution scanning electron microscopy, which images features almost 100× smaller than possible in an optical microscope. For suspensions that are dilute and films that are thick compared to the particle diameter, the translational and rotational diffusion coefficients determined by single-particle tracking agreed with existing theoretical predictions. In thinner films, a striking and unexpected dynamical pairing of nanospheres was observed, suggesting a balance of capillary and hydrodynamic interactions. Nanospheres at high concentration displayed subdiffusive caged motion and hexagonal-lattice crystallization. Concentrated nanorods in the thinner films transiently assembled into finite stacks but did not achieve high tetratic liquid crystalline order, perhaps because of spherical impurities. A small spherical microparticles on a cylindrically curved liquid interface, to maintain constant contact angle about its wetted periphery, locally induces a quadrupolar interface deformation. Measured by optical profilometry, this deformation was compared to a recent theoretical expression, and good agreement was noted. The interface quadrupoles lead to particle capillary interactions in analogy to a 2d electrostatic quadrupoles, and as one consequence, spheres on a cylindrical interface assemble tetragonally. The assembly was monitored in the optical microscope, with particles driven to assembly as predicted, into a tetragonal lattice aligned with the underlying cylindrical axis. Lastly, ionic liquids and their mixtures with low molecular weight solvents were applied as flotation liquids for cryo-ultramicrotomy. With control of glass transition temperature and liquid viscosity, flat and ultra-thin sections were reliably floated onto transmission electron microscopy grids at cryogenic temperature. Compared to established flotation media for soft polymer systems, the required time and skill are significantly reduced, and the operator was not exposed to noxious fumes

Bone mass and exercise in adult premenopausal women

This thesis reports the results of three studies investigating the links between exercise and bone mass in premenopausal women at or beyond the age of peak bone mass. In the first study, bone mass and body composition, historical physical activity, calcium intake and menstrual status were measured in 43 premenopausal swimmers (Australian Union of Senior Swimmers - AUSSI) and 44 controls to test the proposition that swimming has a detrimental effect on bone. In the second study, 152 adult premenopausal women provided data to elucidate important determinants of current bone mass. The third study tested the ability of home-based “impact” exercise programs (~ one year) to improve bone mass in adult premenopausal women identified as having low bone mass for age at the hip (proximal femur), lumbar spine and/or ultradistal radius in the first two studies. Women were randomly assigned to exercise or control groups and subsequently pair-matched on the bases of age, regional bone mass and body mass index. Physical activity, calcium intake and menopausal status were determined retrospectively. The results of the first study indicated that endurance-style swimming in women averaging over two hours per week (current) and ~1.5 hours per week (lifetime) had no negative effect on the skeleton. This conclusion was based upon finding: no significant differences between swimmers and controls for bone mass at any site; significantly more instances of low bone mass in controls; swimmers in the upper quartile for swimming participation had higher bone mass than those in the lowest quartile despite over a four hour per week difference in mean swimming participation (previous three years). The second investigation indicated that lean mass was a stronger independent predictor of bone mass than fat mass, age, weight or body mass index though none produced correlations of more than moderate strength. In terms of Historical physical activity, “Very hard physical activity” (> seven METS) undertaken during the second, third and fourth decades, was the best independent predictor of current bone mass while grip strength was the best predictor of current bone mass of all the functional tests carried out. Maximum oxygen uptake (unadjusted for body weight) was a significant independent predictor of bone mass in the lower extremities. University staff volunteers (20) were used to design the impact exercise programs which involved either dropping from various heights with bilateral or single foot landings or arresting falls onto both or a single hand (forceplate). Two protocols were designed which targeted low bone mass at the hip and spine or the distal radius, both employing unilateral landings. Exercisers achieved significant improvements from baseline and against controls at each of the target-bone sites even with relatively low exercise compliance. It was concluded that this form of exercise is a safe and effective means of improving low bone mass site-specifically with loads of approximately four times body weight (hip and spine) and one body weight (radius)

Multimetal smithing : An urban craft in rural settings?

Multimetal smithing should be defined as the use of more than one metal and/or different metalworking techniques within thesame crafts-milieu. This complex metalworking has long been linked to centrality, central places and urbanity in Scandinavia.It has been extensively argued that fine casting and smithing, as well as manufacture utilizing precious metals was exclusivelyundertaken within early urban settings or the “central places” pre-dating these. Furthermore, the presence of complex metalcraftsmanship has been used as a driving indicator of the political, social and economic superiority of certain sites, therebyenhancing their identity as “centralities”.Recent research has come to challenge the universality of this link between urbanity, centrality and complex metalworkingas sites in rural settings with evidence of multimetal smithing are being identified. This shows that the relationship between thecraft and centrality (urbanity) must be nuanced and that perhaps multimetal craftsmanship should be reconsidered as an urbanindicator.The thesis project “From Crucible and onto Anvil” started in 2015 and focuses on sites housing remains of multimetalcraftsmanship dating primarily from 500-1000 AD. Within the project a comprehensive survey of sites will be used to evaluate thepresence of multimetal craftsmanship in the landscape. Sites in selected target areas will also be subject to intra-site analysisfocusing on workshop organisation, production output, metalworking techniques and chronological variances.A key aim in the project is to elucidate the conceptual aspects of complex metalworking. The term multimetality is used toanalytically frame all the societal and economic aspects of multimetal craftsmanship. Through this inclusive perspective both thecraftsmanship and the metalworkers behind it are positioned within the overall socioeconomic framework. The metalworkers,their skills and competences as well as the products of their labour are viewed as dynamic actors in the landscape and on thearenas of political economy of the Late Iron Age.The survey has already revealed interesting aspects concerning multimetal smithing and urbanity. Although the multimetalsites do cluster against areas of early urban development there are also other patterns emerging. Multimetal craftsmanship – both as practice and concept – was well represented in both rural peripheral settings and urban crafts-milieus. This means that therole of multimetality as part of an “urban conceptual package” is crucial to investigate. Such an approach will have the dual endsof properly understanding the craft and its societal implications, but also further the knowledge of the phenomenon of urbanityas a whole. Was multimetal smithing part of an “urban package” that spread into the rural landscape? Did the multimetality differbetween urban and rural crafts-milieus? How does early urbanity relate to the chronology of multimetal craftsmanship?This paper aims to counter these questions using examples from the survey of multimetal sites conducted within the thesisproject. A comparison between selected sites will be presented. The purpose of this is to evaluate the role of multimetality withinthe “urban package” and discuss the role of complex metalworking in the establishment of urban arenas of interaction in LateIron Age Scandinavia