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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Market penetration of biodiesel and ethanol

Szulczyk, Kenneth Ray 17 September 2007 (has links)
This dissertation examines the influence that economic and technological factors have on the penetration of biodiesel and ethanol into the transportation fuels market. This dissertation focuses on four aspects. The first involves the influence of fossil fuel prices, because biofuels are substitutes and have to compete in price. The second involves biofuel manufacturing technology, principally the feedstock-to-biofuel conversion rates, and the biofuel manufacturing costs. The third involves prices for greenhouse gas offsets. The fourth involves the agricultural commodity markets for feedstocks, and biofuel byproducts. This dissertation uses the Forest and Agricultural Sector Optimization Model-Greenhouse Gas (FASOM-GHG) to quantitatively examine these issues and calculates equilibrium prices and quantities, given market interactions, fossil fuel prices, carbon dioxide equivalent prices, government biofuel subsidies, technological improvement, and crop yield gains. The results indicate that for the ranges studied, gasoline prices have a major impact on aggregate ethanol production but only at low prices. At higher prices, one runs into a capacity constraint that limits expansion on the capacity of ethanol production. Aggregate biodiesel production is highly responsive to gasoline prices and increases over time. (Diesel fuel price is proportional to the gasoline price). Carbon dioxide equivalent prices expand the biodiesel industry, but have no impact on ethanol aggregate production when gasoline prices are high again because of refinery capacity expansion. Improvement of crop yields shows a similar pattern, expanding ethanol production when the gasoline price is low and expanding biodiesel. Technological improvement, where biorefinery production costs decrease over time, had minimal impact on aggregate ethanol and biodiesel production. Finally, U.S. government subsidies have a large expansionary impact on aggregate biodiesel production, but only expand the ethanol industry at low gasoline prices. All of these factors increase agricultural welfare with most expanding producer surplus and mixed effects on consumers.
72

Dynamics of innovation of biofuel ethanol. three decades of experience in the U.S. and in Brazil

Berger, Elena M. 15 November 2010 (has links)
This dissertation draws on the burgeoning field of innovation of low carbon technologies. Using the functions of innovation systems, this study explores the process of innovation of biofuel ethanol in the U.S. and in Brazil. It uses "process theory" to build a narrative of historical events that represent the innovation trajectory of ethanol biofuel in the U.S. and in Brazil over a period of thirty years. The data is drawn from newspaper articles from the New York Times, Washington Post, and O Estado de Sao Paulo published between 1975 and 2008. Results of this research confirm findings published previously that innovation performs better when the main actors in the innovation process act under clear and well defined policy targets, and when the innovation environment contributes to building positive expectations about the technology. The empirical findings build upon the literature and validate early claims that the alignment of goals between technology producers and users is an inducer of innovation. Moreover, the analysis presented shows that by developing new capabilities, technology users in the downstream market broaden the innovation environment and facilitate the adoption of the emerging technology by new users and markets. For example, the automobile sector has been participating actively in the ethanol technological innovation system in Brazil, facilitating the innovation flow between upstream and the downstream market. This has not been the case in the U.S., where the automobile sector has not found incentives to participate in the ethanol technological innovation systems.
73

Acute and chronic ethanol effects on liver p42/44 mitogen activated protein kinase /

Weng, Yu-I, January 2001 (has links)
Thesis (Ph. D.)--University of Missouri--Columbia, 2001. / "December 2001." Typescript. Vita. Includes bibliographical references (leaves 181-193). Also available on the Internet.
74

Ethanol dependence in Drosophila larvae

Robinson, Brooks Gregory 15 October 2013 (has links)
Addiction to alcohol is a disease of changed behavior that is uniquely human in it's complexity. Because of this, researchers have strived to develop animal models of individual endophenotypes of alcoholism in hopes that the larger picture will eventually come into focus. Recent studies in Drosophila have shown that many complex alcohol-related behaviors are conserved in this genetic model system. The series of projects presented in this dissertation outline the first account of physiological ethanol dependence in Drosophila. We first show that Drosophila larvae are able to form conditioned associations between an aversive heat stimulus and an attractive odor. We then show that an acute, low-dose ethanol exposure disrupts this learning ability. Finally, we present data that demonstrate that larvae adapt to the presence of chronic ethanol to the point that they only perform normally in the learning assay when ethanol is present in the animal. We then propose that the major mechanism for this dependence involves ethanol regulating the acetylation level and therefore expression level of a large number of genes by inhibiting histone deacetylase enzymes. These experiments set the groundwork for the analysis of a network of genes, connected through interactions with histone deacetylase enzymes, that are involved in producing ethanol dependence. / text
75

Gait transitions in C. elegans

Topper, Stephen Matthew 17 February 2014 (has links)
The ability to switch between different forms of locomotion is critical to many aspects of survival, whether it is switching from walking to running to evade predators, or switching to a slower gait to obtain food. Uncovering the mechanisms behind gait transitions has implications for many fields, from treating Parkinson Disease to understanding the impact of drugs of abuse on movement. However, the mechanisms of gait transitions are not well understood. The experiments outlined in this thesis sought to understand the neuronal basis for gait switching. This work employed the nematode Caenorhabditis elegans, a unique model organism chosen for its genetic tractability and fully characterized nervous system. C. elegans displays different forms of motion: crawling on land and swimming in liquid. First, I sought to determine the mechanisms for switching between these forms of motion in collaboration with Dr. Andres Vidal-Gadea. In the process, we discovered that crawling and swimming actually represent distinct gaits in contrast to recent reports that suggested they were merely a single gait. We further elucidated mechanisms for gait transition in C. elegans. For instance, we found that the transition to crawling required viii the D1-like dopamine receptors DOP-1 and DOP-4; and activation of dopamine neurons via the light-activated cation channel Channelrhodopsin2 was sufficient to induce crawling behavior in worms immersed in liquid. Conversely, photoactivation of serotonergic neurons expressing Channelrhodopsin2 induced swim-like behavior on land. Finally, laser microablation of dopaminergic or serotonergic neurons was sufficient to impair the transition to crawl or swim, respectively. Together these results show that transitions to crawling and swimming are controlled by dopamine and serotonin respectively. Next I wanted to better understand how gait transitions are impaired by a drug of abuse, alcohol. I found that, as in other organisms, ethanol disrupts gait transitions, causing worms in water to inappropriately transition from swim to crawl and to display other land-specific behaviors. Animals lacking the D1-like dopamine receptor DOP-1 were resistant to the ethanol-induced transition to crawl. Finally, I found that several interneurons required for the transition to crawl. Specifically, laser microablation of the DOP-4 receptor-expressing neuron RID or the DOP-1-expressing neurons PQR or RIS resulted in a significant impairment in the time to crawl onset. Overall, the findings presented in this thesis represent the first evidence that C. elegans uses an evolutionarily conserved mechanism to transition between gaits and provides the beginning of a molecular description of gait transitions. / text
76

Exploring Pretreatment Methods and Enzymatic Hydrolysis of Oat Hulls

Perruzza, Amanda 13 January 2011 (has links)
This thesis describes a way to achieve higher conversion rates of sugars from lignocellulosic biomass that can then be used for cellulosic ethanol production. Using oat hulls as the biomass, several chemical and physical pretreatment techniques were explored to overcome the recalcitrance and allow access to cellulose and hemicellulose. Experimentation with enzyme cocktails and dosing was done to obtain the highest conversions of cellulose and xylan to produce sugars. High solids-loading of the substrate, 14-16%, enabled higher conversion rates and would amount to lower cost of production in a commercial facility; however, end-product inhibition by the accumulation of inhibitors is also realized. To remove inhibition, a solid-liquid separation step was implemented which allowed enzymes to operate at a higher efficiency. The best combination of pretreatment and enzymatic hydrolysis led to a glucose of 89% and xylose yield of 84%, for trials conducted in a 20L bioreactor.
77

Efficiency and Emissions Study of a Residential Micro–cogeneration System Based on a Stirling Engine and Fuelled by Diesel and Ethanol

Farra, Nicolas 31 December 2010 (has links)
This study examined the performance of a residential micro–cogeneration system based on a Stirling engine and fuelled by diesel and ethanol. An extensive number of engine tests were conducted to ensure highly accurate and reproducible measurement techniques. Appropriate energy efficiencies were determined by performing an energy balance for each fuel. Particulate emissions were measured with an isokinetic particulate sampler, while a flame ionization detector was used to monitor unburned hydrocarbon emissions. Carbon monoxide, nitric oxide, nitrogen dioxide, carbon dioxide, water, formaldehyde, acetaldehyde and methane emissions were measured using a Fourier transform infrared spectrometer. When powered by ethanol, the system had slightly higher thermal efficiency, slightly lower power efficiency and considerable reductions in emission levels during steady state operation. To further study engine behaviour, parametric studies on primary engine set points, including coolant temperature and exhaust temperature, were also conducted.
78

Efficiency and Emissions Study of a Residential Micro–cogeneration System Based on a Stirling Engine and Fuelled by Diesel and Ethanol

Farra, Nicolas 31 December 2010 (has links)
This study examined the performance of a residential micro–cogeneration system based on a Stirling engine and fuelled by diesel and ethanol. An extensive number of engine tests were conducted to ensure highly accurate and reproducible measurement techniques. Appropriate energy efficiencies were determined by performing an energy balance for each fuel. Particulate emissions were measured with an isokinetic particulate sampler, while a flame ionization detector was used to monitor unburned hydrocarbon emissions. Carbon monoxide, nitric oxide, nitrogen dioxide, carbon dioxide, water, formaldehyde, acetaldehyde and methane emissions were measured using a Fourier transform infrared spectrometer. When powered by ethanol, the system had slightly higher thermal efficiency, slightly lower power efficiency and considerable reductions in emission levels during steady state operation. To further study engine behaviour, parametric studies on primary engine set points, including coolant temperature and exhaust temperature, were also conducted.
79

Exploring Pretreatment Methods and Enzymatic Hydrolysis of Oat Hulls

Perruzza, Amanda 13 January 2011 (has links)
This thesis describes a way to achieve higher conversion rates of sugars from lignocellulosic biomass that can then be used for cellulosic ethanol production. Using oat hulls as the biomass, several chemical and physical pretreatment techniques were explored to overcome the recalcitrance and allow access to cellulose and hemicellulose. Experimentation with enzyme cocktails and dosing was done to obtain the highest conversions of cellulose and xylan to produce sugars. High solids-loading of the substrate, 14-16%, enabled higher conversion rates and would amount to lower cost of production in a commercial facility; however, end-product inhibition by the accumulation of inhibitors is also realized. To remove inhibition, a solid-liquid separation step was implemented which allowed enzymes to operate at a higher efficiency. The best combination of pretreatment and enzymatic hydrolysis led to a glucose of 89% and xylose yield of 84%, for trials conducted in a 20L bioreactor.
80

Composition and yield of eight switchgrass cultivars in Alabama

Crider, Lindsay J., Bransby, David I., January 2009 (has links)
Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 29-30).

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