acase@tulane.edu / 1 / hong zhang

Thesis (M.S.)--Oregon State University, 1971. / Typescript (photocopy). Includes bibliographical references. Also available online.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Darrin J. Pochan, Dept. of Materials Science & Engineering. Includes bibliographical references.

<p>In this study, the main objective was to investigate the tolerance of platinum based binary anode catalysts for CO poisoning from 10ppm up to1000ppm and to identify the<br /> best anode catalysts for PEMFCs that tolerates the CO fed with reformed hydrogen.</p>

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When Darwin introduced natural selection in 1859 as a key mechanism of evolution, little was known about the underlying cause of variation within a species. Today we know that this variation is caused by the acquired genomic differences between individuals. Polymorphism, defined as the existence of multiple alleles or forms at a genomic locus, is the technical term used for such genetic variations. Polymorphism, along with reproduction and inheritance of genetic traits, is a necessary condition for natural selection and is crucial in understanding how species evolve and adapt. Many questions regarding polymorphism, such as why certain species are more polymorphic than others or how different organisms tend to favor some types of polymorphism among others, when solved, have the potential to shed light on important problems in human medicine and disease research. Some of these studies require more diverse species and/or individuals to be sequenced. Of particular interest are species with the highest rates of polymorphisms. For instance, the sequencing of the sea squirt genome lead to exciting studies that would not be possible to conduct on species that possess lower levels of polymorphism. Such studies form the motivation of this thesis. Sequencing of genomes is, nonetheless, subject to its own research. Recent advances in DNA sequencing technology enabled researchers to lead an unprecedented amount of sequencing projects. These improvements in cost and abundance of sequencing revived a greater interest in advancing the algorithms and tools used for genome assembly. A majority of these tools, however, have no or little support for highly polymorphic genomes; which, we believe, require specialized methods. In this thesis, we look at challenges imposed by polymorphism on genome assembly and develop methods for polymorphic genome assembly via an overview of current and past methods. Though we borrow fundamental ideas from the literature, we introduce several novel concepts that can be useful not only for assembly of highly polymorphic genomes but also genome assembly and analysis in general.

This dissertation focuses on investigating the morphologies, optical and photoluminescence properties of porphyrin nanostructures prepared by the self-assembly method. The study is divided into three main parts. In the first part, a large variety of porphyrin nanostructures, including nanoplates, nanofibers, nanoparticles and nanowires, were obtained through direct acidification of tetra(p-carboxyphenyl)porphyrin (TCPP) in aqueous solution. Protonation of the carboxylate groups of TCPP resulted in the formation of nanoplates through the J-aggregation of the porphyrin. Further protonating the core nitrogens of TCPP formed the porphyrin diacids which organized into well-defined structures through their interactions with counter-anions in the solution. The structures of the resulting assemblies were found to be counterion dependent. In the second part of this work, we explored the optical memory effect of the porphyrin thin film. We found that the morphology and the emission of the porpyrin thin film on Si can be changed by varying the pH of its surrounding solution. The changing in morphology and light emission of the thin film resulted from the protonation or deprotonation of TCPP'S core nitrogens. By selectively deprotonating the TCPP dications in a confined region utilizing the water meniscus between an AFM tip and the surface, Fluorescence patterns can be generated on the thin film. The fluorescence patterns can be easily erased by re-protonating the porphyrin. In the third part of this study, porphynoid nanoparticles were deposited on a surface energy gradient, and then characterized by AFM in order to investigate how the surface energy influences thier morphologies. The surface energy gradient was prepared by selectively oxidizing a self-assembly monolayer of octadecyltrichlorosilane (OTS) by UV-ozone. The nanoparticles disassemble into smaller nanoparticles with narrower size distribution on the surface with higher surface energy. Lastly, we engaged in characterizing the morphologies of polymer nanocomposites prepared by layer-by-layer assembly for wettability control. The surface roughness of the nanocopmosite in air and in salt solutions was also measured to study the correlation between the wettability of the polymer surface and its surface roughness.

Taiwan semiconductor manufacturing industry ranks top in the world for the production and has a great contribution to Taiwan economics. However, the industry produces a significant amount of volatile organic compounds (VOC) into the air. According to EPA of Taiwan, the annual VOC emission amounts from the industry were approximately five thousand tons, a major stationary source of VOC emission. The EPA has implemented the air pollution control regulation for semiconductor industry, in which the VOC emission amount should be below <0.6 kg/hr or the removal efficiency should be >90% for each factory . The conventional control technologies for the VOC emissions was concentration using zeolite followed by thermal oxidation. However, the high boiling points of VOC is difficult to desorbed from zeolite and it required the water to wash the zeolite. This would reduce the removal efficiency of zeolite. This control processes have high operation cost and may produce byproducts required for further treatment. Advanced chemical oxidation process (AOP) recently has gained tremendous attention as an emerging control technology of VOC due to low treatment cost and few oxidation byproducts. The major oxidant of the technology is believed to be hydroxyl radicals, which can react organic compounds at very reaction rates. A majority of VOC emissions from the semiconductor industry are highly soluble and can be easily dissolved into water by scrubbing process. However, the wet scrubbing process can produce a significant amount of wastewater. The objective of this study was to investigate the feasibility of using wet scrubber and O3/H2O2/catalyst process on controlling the VOC emissions from the semiconductor manufacturing industry. A full scale of process of 1000 CMM flowrate was designed and built along with a semiconductor packaging facility. Results showed that major compounds of the VOC exhaust were iso-propanol, PGMEA, PGME and methyl ethyl keton. The inlet concentrations of THC significantly varied from 50 to 600 ppmv as methane. The AOP process can removed 90-95% of VOCs and the scrubbing water can be recycled and reused at least 95%. The capital cost of the system was NT20,000,000 with the annual operation cost of NT120,000 which was only 36-40% of it for the concentration using zeolite followed by thermal oxidation.

During micro packaging process, the products are almost manufactured by hand work. The development of the micro packaging system can reduce human error and automatic process is implemented. This paper describes a method of motion planning of sliding, and rotating manipulations by a adjustable gripper. In precision assembly tasks such as a screw insertion, the task accuracy required for each direction in the task space is different. This paper discusses the adjustable gripper applied on automatic assembly system. The accurate determination of the position and shape of the objects are analyzed and identified by machine vision. The package time is reduced and the product yield rate is raised.

The objective of this research is to investigate synthetic and polypeptide block copolymers, the structures they form, their response to various stimuli in solution and their capabilities for use in biomimicry. The self-assembled structures of both polymers will be used as a basis for the templating of hydrogels materials, both in the interior and on the surface of the vesicles. The resulting particles will be designed to show the structural and mechanical properties of living cells. The synthetic block copolymers are a polyethylene glycol and polybutadiene (PEO-b-PBd) copolymer and the polypeptide block copolymers are Lysine and Glysine (K-b-G) copolymers. Investigation of the structures synthetic block copolymers will focus on whether the polymer can form vesicles, how small of a vesicle structure can be made, and the formation of internal polymer networks. Subsequent investigations will look at the needed steps for biomimicry, using the synthetic block copolymers as a starting point and transitioning to a polypeptide block copolymer. The Lysine-Glysine copolymers are a new system of materials that form fluid vesicle structures. Therefore, we must characterize its assembly behavior and investigate how it responds to solution conditions, before we investigate how to make a cellular mimic from it. The size and mechanical behavior of the K-G vesicles will be measured to compare and contrast with the synthetic systems. The goals for creating a biomimic include a hollow sphere structure with a fluid bilayer, a vesicle that has controllable mechanical properties, and a vesicle with controllable surface chemistry. Overall, these experiments were a success; we showed that we can effectively control the size of vesicles created, the material properties of the vesicles, as well as the surface chemistry of the vesicles. Investigations into a novel polypeptide block copolymer were conducted and the block copolymer showed the ability to create vesicles that are responsive to changing salt and pH concentrations.