Solution Processable Carbon-Based Electronics

Fabricating electronic devices using solution-based processing methods opens up a broad range of potential applications that are inaccessible to conventional semiconductor fabrication technologies. The chemically diverse family of carbon-based materials are suitable for this purpose with almost limitless possibilities for molecular tailoring. The present work is a study of some of the materials for and device physics of field-effect transistors based on solution processable layers. Each aspect of this work is chosen to address a current difficulty in the development solution-processable carbon-based electronics. For portable and battery-powered applications, low-power circuits are required. This can be achieved by using a complementary logic circuit architecture (that requires both electron and hole transporting semiconductors) where the discrete devices operate at low voltages. Practically, this requires a high capacitance gate dielectric which is compatible with solution processing of a range of semiconductor materials. One family of molecules suitable for this purpose are self-assembling phosphonic acids that can form molecular monolayers. In the present study, molecular tailoring of this family of molecules is investigated as a route towards improving the compatibility of these dielectrics with solution processed semiconductors. One of the difficulties with utilising a complementary logic circuit architecture is the requirement of a suitable electron transporting semiconductor. This semiconductor must be solution-processable, exhibit a high electron mobility and be stable against degradation upon atmospheric exposure. Although many p-channel semiconductors fulfil these requirements, equivalent performance in many families of n-channel semiconductors remains challenging. In the present study, the use of fullerenes, a widely used family of semiconductors, is explored for implementation as an n-channel material in field-effect transistors. Their electronic structure is controlled by chemical tailoring of each molecule and the impact of this parameter variation on the air-stability of these fullerenes is assessed. Graphene, potentially one of the most important materials for future electronics, is currently impractical to prepare over large areas. Chemical derivation routes are sought which allow processing of graphene from solution. One of the most important routes is solution phase exfoliation of graphene oxide followed by thermal or chemical reduction. Unfortunately this introduces a high density of defects within the final graphene layer which ultimately limits the charge-carrier mobility. Here, a milder oxidation with surfactant-assisted solution phase exfoliation is investigated as a route to improving the quality of graphene films following reduction. The electronic properties of thin- films of these chemically-derived graphene layers are explored as the active layer in field-effect transistors

L^2 part of the heavy-quark potential from dual QCD and heavy-quark spectroscopy

We use the classical approximation to the dual QCD field equations to calculate the term in the heavy-quark potential that is proportional to angular momentum squared. This potential combined with the potentials obtained in our earlier work gives a result which is essentially the dual of the potential acting between a monopole-antimonopole pair carrying Dirac electric dipole moments and rotating in a relativistic superconductor. These potentials are used to fit the masses of the low-lying states of the cc̅ and bb̅ systems. The agreement, achieved with only four parameters, two of which are roughly determined in advance, is better than 1%. We also predict the masses of the lightest cb̅ states

Mode-matching analysis of a shielded rectangular dielectric-rod waveguide

Rectangular cross-section dielectric waveguides are widely used at millimeter wavelengths. In addition, shielded dielectric resonators having a square cross-section are often used as filter elements, however there is almost no information available on the effect of the shield. Rectangular or square dielectric waveguide is notoriously difficult to analyze, because of the singular behaviour of the fields at the corners. Most published analyses are for materials with a low dielectric constant, and do not include the effects of a shield. This paper describes a numerically efficient mode matching method for the analysis of shielded dielectric rod waveguide, which is applicable to both low and high dielectric constant materials. The effect of the shield on the propagation behaviour is studied. The shield dimensions may be selected such that the shield has a negligible effect, so that results can be compared with free space data. The results are verified by comparison with several sets of published data, and have been confirmed by measurement for a nominal 'e' r of 37.4

"A Munich situation": pragmatic cooperation and the Johannesburg Non-European Affairs Department during the early stages of apartheid

M.A. Uinversity of the Witwatersrand, Faculty of Humanities, 2012This dissertation aims to reveal and explain how the evolving relationship between the Johannesburg City Council and the Native Affairs Department affected urban African administration during the early stages of Apartheid. It will add detail to a selection of key disputes between the levels of Government in the mid 1950s and examine the Department’s onslaught against the Council towards the end of the decade. It will trace the emergence of a culture of pragmatic cooperation during the early 1960s and analyse internal divisions within the United Party group in Council. It will finish by tracing the emergence of the Administration Board system and suggesting that the period of pragmatic cooperation played a role in delaying the ultimate decision to remove urban African administration from local authorities. Throughout this dissertation the influence of key personalities like W.J.P Carr, Manager of the Johannesburg Non-European Affairs Department and Patrick Lewis, the Chairman of the Non-European Affairs Committee, will be explored

Hitting the Bullseye: The Influence of Technical Debt on the Accuracy of Effort Estimation in Agile Projects

As firms rapidly develop solutions in order to increase revenue and market share, software development decisions considered to be temporary shortcuts and/or compromises may be implemented. These shortcuts represent “technical debt,” a metaphor which succinctly describes a software solution that should be “paid in full” or remediated in the future. Software architects and developers intend to resolve the “debt” in future product releases, but practitioners recognize that the challenge of always innovating may indefinitely postpone this remediation effort. Further, the accumulation of technical debt may have long term impact on the product’s maintainability by the software development teams and, consequently, impact the effort estimate delivered to management for forecasting product delivery timelines and product revenue expectations. While there are multiple publications that have studied effort estimation in traditional and agile software development strategies, there is limited research which considers technical debt during the estimation effort. As a result, the purpose of this dissertation is to design and propose a research model intended to determine whether or not the consideration of technical debt during the effort estimation process will improve the accuracy of the effort estimate in an agile project

Alien Registration- James, Lillian (Camden, Knox County)

https://digitalmaine.com/alien_docs/15127/thumbnail.jp

From the Temporal to the Eternal: The Normative Philosophy of Anselm of Canterbury

The purpose of this thesis is to examine the extent to which Anselm of Canterbury can be described to have possessed a consistent normative philosophy which coherently addressed the question of how the individual ought to act. By so doing it will seek to extend the contemporary commentary of Anselm’s ethical philosophy beyond the abstract and meta-ethical and analyse the ways in which Anselm’s letter collection can be used to show pragmatic approaches to ethical questions. In examining this field, this thesis contains what amounts to two interdependent parts. The first will deal almost exclusively with Anselm’s anthropology, theory of will, and ethical philosophy. The second will, broadly speaking, examine the impact of his theology and ethical philosophy upon his societal and political beliefs. This will by no means amount to an exhaustive study of Anselm’s normative thought; rather, it will provide key examples of how such an approach opens up new lines of research and furthers the field of Anselm studies, addressing several past issues of contention

One Dimensional Chemistry and the Generalised Local Density Approximation

In this thesis we explore two distinct topics: a unique model of one dimensional chemistry and the development of the generalised local density approximation. The specific one dimensional system we study is one in which three dimensional particles, both electrons and nuclei, have been strictly confined to move on a line. This means we retain the Coulomb interaction of the three dimensional particles. This is problematic, the singularity of this interaction is exceptionally strong in one dimension and requires special techniques be used to circumvent it. In our study we employ the Dirichlet boundary conditions, which require the wavefunction to vanish whenever two particles touch. This brings some severe consequences including, most controversially, that the nuclei are impenetrable to the electrons. However it does permit finite binding energies of electrons to nuclei and has a number of unique features which make it an interesting system to study for insight into electron behaviour. Here we explore the mechanics of chemistry within this model. We construct an unusual periodic table for one dimensional elements and explore the mechanisms by which they bind into molecules. Ultimately, we are able to develop a set of simple rules with which one can easily predict the outcome of a reaction in this unique model. The generalised local density approximation is a new method for constructing density functional approximations. The local density approximation, the most simplistic of all density functionals, is built off the properties of the infinite uniform electron gas and as result replicates them exactly. It is also possible to construct finite uniform electron gases and, contrary to expectations, the regular local density approximation is unable to model these finite gases correctly. The generalised local density approximation incorporates these finite gases into its construction. We account for their differences from the infinite gases by introducing a new parameter which measures the proximity of electrons at a point in space. We can then construct a correlation functional for one dimensional systems using a method which closely resembles that used for previous local density approximations. Because of the definition of the new parameter, one would formally consider this functional to be a meta-GGA functional. However it retains the exceptionally simple form of a local density approximation. This new functional is observed to have greatly improved accuracy compared to the standard local density approximation when tested against a variety of systems, including reactions of the one dimensional molecules identified earlier. Although we only construct a one dimensional functional here, the method is easily generalised to other dimensions

Development of new methods in solid-state NMR

Many chemically important nuclei are quadrupolar with half-integer spin (i.e., spin I = 1.5, 2.5, etc.) The presence of quadrupolar broadening for such nuclei can limit the information that may be extracted using NMR. MAS is able to remove first-order quadrupolar broadening but can only reduce the second-order contribution to the linewidth. The MQMAS and STMAS techniques have enabled high-resolution NMR spectra of half-integer quadrupolar nuclei in the solid state to be obtained by two-dimensional correlation under MAS conditions. Both of these experiments have several well-known limitations. One is that the conversion pulses in particular are very inefficient and the other is that the longer acquisition times required for two-dimensional experiments can be a limiting factor. Both of these disadvantages are addressed in this thesis. For the former case, existing composite pulse schemes designed to improve the efficiency of the conversion of multiple-quantum coherences are compared using 27Al and 87Rb MQMAS NMR of a series of crystalline and amorphous materials. In the latter case, a new experiment, named STARTMAS, is introduced that enables isotropic spectra of spin I = 1.5 spectra to be acquired in real time. The theoretical basis of the technique is explained and its applicability demonstrated using 23Na and 87Rb NMR of a wide range of solids. The nuclear Overhauser effect (NOE) is one of the most widely exploited phenomena in NMR and is now widely used for molecular structure determination in solution. NOEs in the solid state are rare and those to quadrupolar nuclei rarer still, this being due to the general absence of motion on the correct timescale and the usual efficiency of quadrupolar T1 relaxation, respectively. In this thesis, 11B{1H} transient NOE results are presented for a range of solid borane adducts. A comparison is made of the 11B NMR enhancements observed under MAS and static conditions and a rationale is proposed for the behaviour in the latter case