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The effect of scale on the conversion to products in flash vacuum pyrolysis experiments was studied using four model reactions. Overall, conversion was dependent on rection scale up to 0.5 g, but above 0.5 g, the effect was minimal and within experimental error. This effect was shown to be due to variations in contact time of the molecules in the furnace tube. Altering the furnace tube diameter had the effect of increasing the conversion to product. The pyrolysis of ortho-anilinomethylene Meldrum’s acid derivatives was investigated. Typically the 8-substituted quinolin-4-one was obtained as the major product, with a few exceptions. Certain substituents (such as nitro) were found to react with the ketene produced in the reaction to give alternative products, while others (such as chloro- and N-unsubstituted amides) gave the 3-substituted quinolin-4- ones via ipso-cyclisation and migration of the substituent. The regioselectivity of the pyrolysis of meta-anilinomethylene Meldrum’s acid derivatives, to give 5- and 7-substituted quinolin-4-ones, was studied. In general a 3:1 – 4:1 ratio of regioisomers was obtained, in favour of the 7-substituted quinolin-4-one. Substituents capable of hydrogen bonding, such as hydroxy-, were shown to give the 5-substituted quinolin-4-one exclusively and DFT calculations were employed to show that, in these examples, the 5-substituted product was favoured energetically. The pyrolysis of the methylene Meldrum’s acid derivative of 3-aminophenol gave 8-hydroxyquinolizinone as the sole product at low temperatures, with 5- hydroxyquinolinone as the major product formed at higher temperatures. The mechanism involves a regioselective electrocyclisation, followed by a hydrogen transfer and generation of a new ketene. Cyclisation of this ketene gives the quinolizinone. The scope of this reaction was explored, with a number of derivatives synthesised, and substitution on the aminophenol and the ketene generator was tolerated. The reactivity of the quinolizinones was also explored. The hydroxygroup was found to be phenol-like and underwent similar reactions, such as alkylations and acetylations. The compound was found to be highly reactive towards electrophiles, reacting in the 1- and 3- positions of the ring system, often in both positions. The pyrolysis of the aminomethylene Meldrum’s acid derivatives of certain pyridazinones was shown to give pyridopyrazidinediones. In some examples, a 4 second product based on a pyrrolopyridazine ring system was observed and DFT calculations show that the mechanism involves probably an electrocyclisation, followed by a decarboxylation reaction. Pyrolysis of amino acid ester derivatives of methylene Meldrum’s acid were shown to give N-unsubstituted 3-hydroxypyrroles and 1H-pyrrol-3(2H)-ones. Different amino acids were tolerated in the reaction, as were different electronwithdrawing groups in place of the amino acid ester. DFT calculations were employed to explore the mechanism of the reaction. 3-Hydroxypyrrole was also synthesised from the pyrolysis of Meldrum’s acid derivative of glycine tert-butyl ester, and the reactivity of the compound explored for the first time. The compound was found to be reactive towards electrophiles, such as diazonium salts, and could be O-acetylated under appropriate conditions.

Since the civilization, population and living standards of the peoples of the world have increased in such gigantic proportions, especially in the last fifty years; and since the supply of natural resources cannot meet the demand, we have of necessity had to find new materials to take their place. These new materials must fulfill two purposes; namely, to take the place of the natural resources so wantonly destroyed and to meet requirements that the natural materials are not able to meet. Foremost among these new materials are the synthetic resinous materials known as plastics. Plastics are one way of getting around the fact that Nature has not thought of everything. The ability of man to imagine things that he does not see and to fashion these things from what he finds around him is responsible for what we call progress -- and for plastics.

Highly conjugated, extended heterocycles are recognized as important materials for use in electronic applications, and therefore the synthesis and characterization of new molecules of this type are necessary. One method of forming extended heterocycles relies on the dual cyclizations of the hetero-ene-ene-yne motif. By controlling the reaction conditions, these systems can be made to selectively undergo either a pericyclic reaction to form a cinnoline or a coarctate cyclization to form an isoindazole. The ability of the hetero-ene-ene-yne motif to produce two different heterocycles with distinct properties makes it an attractive system to study. Another method of forming extended heterocycles with tunable properties is by fusing aromatic hydrocarbons with aromatic heterocycles such as thiophene. Chapter I introduces the coarctate reaction and gives an overview of the Haley lab's work in this area. Chapter II explores the dual cyclizations of a phenanthrene-based system. In Chapter III an anthraquinone-based cyclization precursor is used to make diazaheterocycle analogs of tetracene. In Chapter IV isoindazoles were joined by an ethynyl linker to either phenyltriazenes and phenyldiazenes to yield molecules that could undergo both coarctate ring-forming and coarcate ring-opening reactions. Chapter V presents the synthesis and characterization of a series of indacenedithiophenes. Chapter VI advances the synthetic methodology of making larger heteroacenes by presenting work toward heterocyclic pentacene analogs. This dissertation includes both previously published and unpublished co-authored material. / 10000-01-01

Thesis (M.Sc.Eng.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Synthetic jet is a quasi-steady jet of fluid generated by oscillating pressure drop across an orifice, produced by a piston-like actuator. A unique advantage of the synthetic jet is that it is able to transfer linear momentum without requiring an external fluid source, and has therefore attracted much research within the past decade. Principal applications include aerodynamic flow boundary-layer separation control, heat transfer enhancement, mixing enhancement, and flow-generated sound minimization. In this thesis, the method of deriving the volume flux equation for a duct is first reviewed, combined with this method, a simplified synthetic jet model is presented, based on the principles of aerodynamic sound, the pressure fluctuation in the acoustic far field is predicted. This model is then been used to predict the minimum synthetic jet cavity resonance frequency, acoustic power, acoustic efficiency, root-mean-square jet speed, acoustic spectrum and their dependence on the following independent parameters: the duct length and radius, the aperture radius, the piston vibration frequency, and the maximum piston velocity. / 2031-01-01

The emerging field of synthetic biology evolved from biological research much the same way synthetic chemistry evolved from chemical research; with accumulated knowledge of the structure of single genes and proteins and the methodologies to manipulate them, researchers turn to forward engineer complex biological systems to effectively manipulate living systems. Much like in the case of enzyme engineering, a rationally designed biological network is currently beyond our reach, and we turn to directed evolution to circumvent this gap in knowledge. Yet the unique nature of live biological networks uncovered new challenges previously unmet by single-gene molecular technologies, and extrapolation of current technologies to the manipulation of multi-component has proven laborious and inefficient. To establish engineering technologies for living cells, novel directed evolution techniques are sought for that are compatible with simultaneous manipulation of multiple biological components in vivo. In this work, we explore techniques for library DNA mutagenesis in the context of single and multiple genes. Chapter 1 provides an overview of the challenges in expanding current in vivo directed evolution methods from single enzymes, to the design pathways and cells. Chapter 2 describes the design and characterization of an assay for combinatorial directed evolution of a single metabolic enzyme. In Chapter 3 we present the utilization of our DNA assembly system, Reiterative Recombination, for attenuation of metabolic pathways. We use a library of promoters to combinatorially vary the expression of genes in the heterologous lycopene biosynthetic pathway in S. cerevisiae. Finally, Chapter 4 explores the calibration of the dynamic range of genetic selection, using metabolic enzyme activity as probe for cell survival.

With the rapid development of DNA synthesis technologies, synthetic biology has made tremendous progress in the past 15 years, in particular for synthetic genomics. Synthetic genomics is a nascent field of synthetic biology, which aims to design new biological systems/organisms to satisfy human needs. Conventional synthetic biology focuses on the redesign, construction and modeling of biological parts, pathways or genomes that do not exist in nature, while synthetic genomics encompasses technologies that allow the generation of chemically synthesized larger parts of genomes or whole genomes, with simultaneous redesign of an organism's genetic material. Synthetic genomics is painting a blueprint for a new era of biology and holds great potential for a multitude of applications, such as pharmaceuticals, biofuels and rapid generation of vaccines against emerging diseases. Chapter One gives an introduction of the current state of the art and challenges of synthetic genomics and the objectives of this study. Chapter Two demonstrates the design and construction strategy of two megabase-long synthetic yeast chromosomes, SynII and SynVII. Chapter Three describes the full characterization of SynII and SynVII. Chapter Four introduces the SCRaMbLE (Synthetic Chromosome Rearrangement and Modification by LoxPsym-mediated Evolution) system and its application in SynII and SynVII. Taken together, this work demonstrates the utility of synthetic yeast for understanding biological systems and its potential for industrial applications.

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