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Experimental methods were developed and used to quantify the behavior of composite materials during heating to support development of heat and mass transfer pyrolysis models. Methods were developed to measure specific heat capacity, kinetic parameters, microstructure changes, porosity, and permeability. Specific heat and gravimetric data for kinetic parameters were measured with a simultaneous differential scanning calorimeter (DSC) / thermogravimetric analyzer (TGA). Experimental techniques were developed for quantitative specific heat measurement based on ASTM standards with modifications for accurate measurements of decomposing materials. An environmental scanning electron microscope (ESEM) was used in conjunction with a heating platform to record real-time video of microstructural changes of materials during decomposition and cooling following decomposition. A gas infusion technique was devised to measure porosity, in which nitrogen was infused into the pores of permeable material samples and used to determine the open-pore porosity of the material. Permeability was measured using a standard pressure differential gas flow technique with improvements over past sealing techniques and modifications to allow for potential high temperature use. Experimental techniques were used to measure the properties of composite construction materials commonly used in naval applications: E-glass vinyl ester laminates and end-grain balsa wood core. The simultaneous DSC/TGA was used to measure the apparent specific heat required to heat the decomposing sample. ESEM experiments captured microstructural changes during decomposition for both E-glass vinyl ester laminate and balsa wood samples. Permeability and porosity changes during decomposition appeared to depend on microstructural changes in addition to mass fraction. / Master of Science

No description available.

The use of polymers in orthopaedics is steadily increasing. In some markets, such as spinal fusion and soft tissue anchors, the polymer polyetheretherketone (PEEK) is already the material of choice in the majority of implants. Despite PEEK’s widespread use, it is often associated with poor osseointegration, which can lead to implant loosening and ultimately failure of the device. Many attempts have been explored to improve the osseointegration of PEEK but none have had widespread clinical success. In this dissertation, a novel surface porous structure has been created, where limiting the porosity to the surface maintains adequate mechanical properties for load bearing applications while providing a surface for improved osseointegration. Careful control of the processing parameters resulted in tunable porous microstructures optimized for bone ingrowth: highly interconnected 200-500µm pores with porosity ranging from 60-85% and pore layers from 300-6000µm thick. Mechanical characterization, including monotonic tensile and compression, tensile fatigue, shear, and abrasion tests, were used to probe the effects of the surface porosity on the relevant mechanical properties of the material. In addition, the effect of surface porosity and surface roughness on the mechanical properties of a range of thermoplastics with varying chemistries and crystallinities was explored. This research showed that there is a great disparity in the notch sensitivity of polymers that correlates to the polymers fracture toughness as well as trends in the monotonic stress-strain curve. The results illustrate that care must be taken in the design of polymeric implants, especially when introducing topographical changes to promote osseointegration, in order to ensure they maintain adequate load-bearing capacity. Finally, preliminary in vitro and in vivo data demonstrated the ability of surface porous PEEK (PEEK-SP) to promote osseointegration. Cells grown on PEEK-SP demonstrated enhanced mineralization and differentiation, suggesting the ability of PEEK-SP to facilitate bone ingrowth. The potential of PEEK-SP was further demonstrated by implantation in a rat femoral segmental defect model which demonstrated bone ingrowth and reduced formation of a fibrous capsule.

No description available.

My work articulates experiences of intimacy and porosity with regard to domestic space. I think of these paintings as fields of interrelatedness which work to dismantle the perceived thresholds between things. The following text brings together the research of my studio practice and a survey of artists, writers, and filmmakers who have charted related spaces of the ordinary, domestic, and porous.

Metal-Organic Materials (MOMs) represent an important division of coordination chemistry. They are self-assembled through the linking of metals with organic ligands. They gained their spotlight among scientists for their aptitude for design and facile synthesis via their multi-component coordination, and their readiness to functionalization. MOMs have been targeted for specific industrial and environmental applications such as gas storage, catalysis and CO2 sequestration. Throughout the past decade, studies have been conducted to develop systematic approaches toward the design and synthesis of functional MOMs. Their synthesis from targeted building units has facilitated their rational design and functionalization. The Molecular Building Block (MBB) approach was first developed to direct the design of MOMs from preset building blocks with specific connectivity amenable to form the overall MOM structure with the desired topology. These building blocks are easily constructed in situ through the chelation of multifunctional ligands (i.e, carboxylic acid, amine, etc) to single ion or cluster metals such as dinuclear copper paddlewheel, and basic zinc acetate. As complexity and applications for MOMs increased, a new approach was developed through the utilization of Supermolecular Building Blocks (SBBs) for the assembly of more complex and higher connected MOM structures. The SBB approach is implemented through the formation of highly coordinated metal-organic polyhedra (i.e, small rhombihexahedron, cuboctahedron, etc) which are further linked by organic ligands to construct functional porous materials with the desired net topology. In this work, we focus on the implementation of a new design approach based on utilizing targeted [M(R-BDC)]n 2D layers as building blocks, i.e Supermolecular Building Layers (SBLs). We target well-known 2D layers that are amenable to pillaring through organic building blocks with specific geometries (i.e quadrangular, hexangular) in order to rationally design and synthesize functional porous metal-organic materials. These SBLs are derived from multifunctional ligands capable of both directing the formation of the 2D layers and pillaring to construct the overall targeted 3D structures with the desired topology (i.e, tbo-MOMs, eed-MOMs, mmm-MOMs, bor-MOMs, and eef-MOMs). Ultimately, we construct isostructural, and isoreticular materials which show potential for many applications such as gas storage, gas separation, and catalysis. These materials have been targeted through the rational choice of specific ligands and proper metals which we recognized to have the capability and the functionality to direct the construction of the desired functional materials and to reach our research goals.

Air-filled porosity (AFP) affected the suppressiveness of organically based plant growth media against Pythium ultimum infection. AFP also interacted with microbial activity, moisture levels altered by covering/uncovering media and water severity of pythium damping-off. It has not been possible to determine a narrow range of AFP required to achieve consistently suppressive media, as AFP has been found to interact with many factors such as microbial activity, temperature shock of media and plants and moisture levels modified by covering and uncovering media, or using different pot heights to modify WHC. The use of different batches of compost and ageing of compost in the seven experiments reported here may also account for some of the different effects of AFP on the severity of Pythium disease. It is not recommended that AFP be used for controlling Pythium damping-off, unless certain conditions, such as microbial activity, can be controlled to a range of specifications also. Variability of compost is one of the principal factors limiting its widespread use, so therefore, improving the quality control during the composting process would be the principal factor which should be investigated in future. / Master of Science (Hons)

This thesis tests the theories of Porosity which are part of my ongoing investigation into the revision and extension of public space in the city. Porosity Research seeks to classify spaces which exist deep within the skin or fabric of privately owned city buildings. The primary vehicle for this interrogation is the use of public art in the form of a set of games called Porosity Games ??? Snakes and Ladders, Hide and Seek and Jenga. These games are played out or performed within the territory of my Australian Research Foundation Discovery Grant outcomes. Their aim is to prove the validity of the research and to provoke interrogation of that research. The marginality of public art makes it ideally suited to the task of commenting on or contradicting the main body of the text of public space in the city. This contradiction is central to the work of this thesis. One of the vital needs or reasons for this work lies in finding ways of preventing cities from being shut down as a result of rampant capitalism in the ???Age of Terror???. Porosity as a strategy attacks this trend. It seeks the dissolution of architecture through a type of mapping which dissolves existing boundaries associated with rights of access. Capitalism needs to be continually measured by mapping or defining what is public against what is private. It can be argued that the social construction of a city is as important as its physical manifestation as buildings. It can also then be argued that a city which allows public space to penetrate its private space enables a healthier social construction. Fundamental to this thesis is the idea that the survival of the Western city depends on an increased density of public space and multiple ground planes as opposed to one. This creates three dimensional public access and alleviates congestion at the level of the street both for cars and for pedestrians. The Porosity Games are a first step in the transformation of the city through their successful reinvention of internal circulation spaces as game space. Game 1: Snakes and Ladders and Game 2: Hide and Seek both operate without interruption by the propriety of the buildings. Game 3: Jenga then intentionally heightened the risk of capture and eviction of the players for transgression within the climate of fear. Both the framework of surveillance and the intention to claim private space for public use, make the performances and the Porosity Research a useful progression in the project of transformation and the city as a plastic medium for the artist to interrogate.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.