In materials science, the traditional methodological framework is the identification of the composition-processing-structure-property causal pathways that link hierarchical structure to properties. However, all the properties of materials can be derived ultimately from structure and bonding, and so the properties of a material are interrelated to varying degrees. The work presented in this thesis, employed artificial neural networks (ANNs) to explore the correlations of different material properties with several examples in different fields. Those including 1) to verify and quantify known correlations between physical parameters and solid solubility of alloy systems, which were first discovered by Hume-Rothery in the 1930s. 2) To explore unknown crossproperty correlations without investigating complicated structure-property relationships, which is exemplified by i) predicting structural stability of perovskites from bond-valence based tolerance factors tBV, and predicting formability of perovskites by using A-O and B-O bond distances; ii) correlating polarizability with other properties, such as first ionization potential, melting point, heat of vaporization and specific heat capacity. 3) In the process of discovering unanticipated relationships between combination of properties of materials, ANNs were also found to be useful for highlighting unusual data points in handbooks, tables and databases that deserve to have their veracity inspected. By applying this method, massive errors in handbooks were found, and a systematic, intelligent and potentially automatic method to detect errors in handbooks is thus developed. Through presenting these four distinct examples from three aspects of ANN capability, different ways that ANNs can contribute to progress in materials science has been explored. These approaches are novel and deserve to be pursued as part of the newer methodologies that are beginning to underpin material research.

The conventional materials discovery is a kind of empirical (“trial and error”) science that of handling one sample at a time in the processes of synthesis and characterization. However, combinatorial methodologies present the possibility of a vastly increased rate of discovery of novel materials which will require a great deal of conventional laboratory work. The work presented in this thesis, involved the practice of a conceptual framework of combinatorial research on BaTiO3-based positive temperature coefficient resistor (PTCR) materials. Those including (i) fabrication of green BaTiO3 base discs via high-throughput dip-pen printing method. Preparation and formulation of BaTiO3 inks (selection of dispersant and binder/volume fraction) were studied. The shape of drying residues and the morphogenesis control of droplet drying were discussed. (ii) investigation of a fast droplet-doping method, which induced the dopant precursor solution infiltrating into the porous BT base disc. Various characterization methods were used to examine the dopant distribution in the body of disc. (iii) devising a high-throughput electrical measurement system including an integrated unit of temperature control and automatic measurement operation, and an arrayed multichannel jig. (iv) synthesis of donor-doped BaTiO3 libraries, which involved lanthanum, erbium, yttrium as donor elements and manganese as an acceptor dopant element respectively. Their temperature dependant resistivities were also explored. The work successfully developed an integrated tool including high-throughput synthesis of a large batch of libraries and high-throughput electrical property measurement for combinatorial research on BaTiO3-based PTCR ceramics. The Abstract ii combinatorial method, thus validated, has the potential to deliver dopant-doped BTbased PTCR libraries rapidly with a very wide range of dopant mixtures and concentrations for electrical property measurement and deserves to be applied to other low level dopant ceramic systems. These approaches are novel and paving the way for other new materials selection and materials research.

This thesis concerns the fabrication and modification of novel oxygen and glucose biosensors as well as the application of these biosensors in oxygen and glucose transport research in cell constructs. In Chapter 1, the principle and development of biosensors has been reviewed. Particular attention is paid to oxygen and glucose mass transport research in cell constructs which are crucial for bio-scaffold design in tissue engineering. Chapter 2 details the materials and methods in oxygen and glucose sensor fabrication, modification and characterization. Chapter 3 presents research into practical challenges in oxygen and glucose sensors. For oxygen sensor, membrane biofouling and sensitivity to stirring effect have been detected and successful progresses have been made to reduce their effects. For glucose sensor, membrane biofouling and oxygen tension reliance affect their performance. Remarkable contributions have been made to improve glucose sensors’ stability and reliability. In particular, micro-biosensors have been introduced in the interests of better sensor adaptability for further biomedical applications. Chapter 4 is the experimental section for biosensor applications, and thus provides a detailed description of the cell culture models used in the thesis. Chapter 5 describes the oxygen partial pressure and glucose concentration measurements using biosensors. 2D and 3D cell culture constructs are investigated and results are discussed in this section. It deserves to be mentioned that the modified oxygen and glucose sensor in this thesis are excellent for in vitro biomedical applications, the simultaneously investigation of PO2 and glucose concentration gradient in 3D cell constructs is also a pioneering work in this research field. Chapter 6 illustrates the overall conclusions resulting from the experiments described in the thesis and points out possible future research directions.

The increasing availability of nanopowders and nanotubes combined with new processing techniques is enabling the development of new multifunctional materials. Carbon Nanotubes (CNTs) are one of the recently discovered allotropic forms of carbon. They have exceptional mechanical, electrical and thermal properties. The application of CNTs in the reinforcement of ceramic nanocomposites has not yet been fully investigated and is the subject of this study. Alumina is the main matrix used in this study. CNTs need to be de-agglomerated and homogeneously distributed in ceramic nanocomposites. Dimethylformamide (DMF) produces fine and stable CNT and alumina dispersions. All nanocomposites were sintered by Spark Plasma Sintering (SPS). Nanocomposites prepared using DMF dispersions showed better dispersions, higher electrical conductivity and mechanical properties as compared to those prepared using ethanol dispersions. The addition of CNTs or Carbon Black (CB) to alumina significantly aids its densification. The CNTs produce significant grain growth retardation. CNTs were found to be well preserved in alumina after being SPSed up to 1900 oC. Structural preservation of CNTs in ceramic nanocomposites depends on the nature of ceramic and SPS processing conditions. The electrical conductivity of alumina – CNT nanocomposites is four times higher as compared to alumina – CB nanocomposites due to the fibrous nature and high aspect ratio of CNTs. Alumina coated CNTs were used for better interfacial adhesion with the matrix. Oxidative resistance of CNTs was increased by coating them with alumina and by decreasing the grain boundary area in alumina – CNT nanocomposites. Coated and uncoated CNTs showed higher mechanical reinforcement in alumina nanocomposite as compared to CB. The future for ceramic – CNT nanocomposites is very bright, especially for applications associated with the electrical and thermal properties. Apart from a good understanding of nanocomposites, the commercial development of CNT based technologies heavily relies on the availability and price of CNTs.

<p> Three dimensional fiber reinforced foam cores (3DFRFC) can have improved mechanical properties under specific strain rates and fiber volumes. This study explored different manufacturing techniques for the 3DFRFC and tested the specimens at dynamic loading rates of 69&ndash;10³ s^&ndash;1. Flexural bend test showed that glass fibers made the samples stronger yet more brittle while quasi-static compression tests showed a decrease in performance with 3DFRFC. High strain impact tests validated previously published studies by showing an 18&ndash;20% reduction in the maximum force experienced by the fiber reinforced core and its ability to dissipate the impact force in the foam core sandwich panel. The results show potential for the cost-effective manufacturing method used in this study to produce an improved composite foam core sandwich panel for armored applications where high strain rates are present and reduce the overall weight of vehicles while maintaining the desired strength performance.</p><p>

Source: Dissertation Abstracts International, Volume: 40-02, Section: B, page: 0875. / Thesis (Ph.D.)--The Florida State University, 1978.

Source: Dissertation Abstracts International, Volume: 34-09, Section: B, page: 4490. / Thesis (Ph.D.)--The Florida State University, 1973.

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