Browsing by Subject "Biomimetics"
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Item Effect of Secondary Interactions on the Fundamental Properties of Small Molecule Models of the Diiron Hydrogenase Active Site(2012-02-14) Singleton, Michael LeeThe unique active site of [FeFe]-hydrogenase has inspired over 300 small molecule models derived from the classical organometallic complex, (?-SRS-)[Fe(CO)3]2. However, no model complex has yet reproduced the hydrogen production capabilities of the enzyme. One reason for this is that the model complexes are not subject to the large number of second coordination sphere interactions that are present in the active site. This work represents two approaches to explore the importance of non-covalent interactions on the properties of small molecule models, (?-SRS)[Fe(CO)3]2 and (?-SRS[Fe(CO)2L]2, of the enzyme active site. First, a series of diiron models with additional steric bulk built into the dithiolate linker that connects the two irons were synthesized. While the electron donating ability of the dithiolate is not drastically altered, as evidenced by infrared spectroscopy, variable temperature - NMR studies show that the energy barrier for certain intramolecular dynamic processes, important in modeling the enzyme active site, is significantly lowered. Electrochemical studies on the all-CO derivatives showed no significant differences in the redox properties of the sterically bulky complexes compared to complexes without added steric bulk. For substituted complexes in which CO is replaced by strong donor ligands greater electrochemical changes were observed, with some events being more accessible by up to 230 mV. One electron oxidation of the disubstituted complexes has produced a series of rare mixed-valent FeIFeII complexes. An X-ray crystal structure of one of these complexes, (?-SCH2C(CH3)2CH2S-)[Fe(CO)2PMe3]2PF6 shows both a semi-bridging carbonyl and an open site similar to the 2-Fe subsite in the Hox state of the enzyme active site. Another method for studying secondary interactions on the model complexes used a host-guest approach to provide an artificial protein environment. Reaction of an aryl sulfonate-containing diiron complex with natural ?-cyclodextrin results in encapsulation of the model. The X-ray crystal structure of the inclusion complex, Na (?-SCH2N(C6H4SO3-)CH2S-)[Fe(CO)3]2?2 ?-cyclodextrin shows complete enclosure of the diiron model within two cyclodextrin units. Solution studies support the formation of an inclusion complex and show that the cyclodextrin is capable of producing significant redox changes to the model complex in H2O. This work has provided a new highly modifiable method for affecting change in the properties of model complexes through intermolecular interactions.Item iFemea (Intelligent Facade Engineered thru Morpho-Ecogenetic Aggregates)(2012-05) Diaz, Rob; Pongratz, Christian; Perbellini, Maria; Park, KuhnThe subject of this thesis is an investigation on an intelligent building skin that improves cross-ventilation (natural) through an embodied space. Intelligent refers to a composite system that either responds to an external energy or a system that can be manipulated and fabricated through a bio-mimetic process. Precedent building skin systems examined in this research provide various technical approaches used to ventilate the building as a "ventilative" device; a means to filter or circulate fresh air from one space to the other. A "mechanical" system will be integrated into a material, controlling possible aperture movements for element (light and/or air) absorption and transmission. The exact configuration will be determined based on the study of biomimicry in plants; which inherits a structure and circulatory system known as the study of morpho-ecogenetics. The aim of this work is to synthesize a membrane with a reinforced mechanical device to influence an aperture operation (open and close) that could be applied to both an external and internal skin of a facade. The term "skin" refers to a light membrane composite that is transparent and malleable and acts as a protective barrier to an interiorly occupied space. The design research will include several test phases that examine the material properties, structure, and applicability when methods such as mechanical, operational, and morphology are integrated.Item Machine Learning Based Classification of Textual Stimuli to Promote Ideation in Bioinspired Design(2013-08-09) Glier, Michael WBioinspired design uses biological systems to inspire engineering designs. One of bioinspired design?s challenges is identifying relevant information sources in biology for an engineering design task. Currently information can be retrieved by searching biology texts or journals using biology-focused keywords that map to engineering functions. However, this search technique can overwhelm designers with unusable results. This work explores the use of text classification tools to identify relevant biology passages for design. Further, this research examines the effects of using biology passages as stimuli during idea generation. Four human-subjects studies are examined in this work. Two surveys are performed in which participants evaluate sentences from a biology corpus and indicate whether each sentence prompts an idea for solving a specific design problem. The surveys are used to develop and evaluate text classification tools. Two idea generation studies are performed in which participants generate and record solutions for designing a corn shucker using either different sets of biology passages as design stimuli, or no stimuli. Based 286 sentences from the surveys, a k Nearest Neighbor classifier is developed that is able to identify helpful sentences relating to the function ?separate? with a precision of 0.62 and recall of 0.48. This classifier could potentially double the number of helpful results found using a keyword search. The developed classifier is specific to the function ?separate? and performs poorly when used for another function. Classifiers developed using all sentences and participant responses from the surveys are not able to reliably identify helpful sentences. From the idea generation studies, we determine that using any biology passages as design stimuli increases the quantity and variety of participant solutions. Solution quantity and variety are also significantly increased when biology passages are presented one at a time instead of all at once. Quality and variety are not significantly affected by the presence of design stimuli. Biological stimuli are also found to lead designers to types of solution that are not typically produced otherwise. This work develops a means for designers to find more useful information when searching biology and demonstrates several ways that biology passages can improve ideation.