Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 96-105).

Described here are detailed kinetic studies probing the structural elements which are crucial for the catalytic activity of dinuclear Zn(II) complexes towards phosphate diester cleavage. First, two sets of dinuclear Zn(II) complexes (a member with and without a bridging oxyanion linker group) were synthesized and their ability to promote the cyclization of 2-hydroxypropyl-p-nitrophenyl phosphate, a common model for RNA, was compared. Kinetic studies indicated that the complexes without the oxyanion linker were more active in promoting the cyclization in methanol under pH controlled conditions at 25 degrees. Quantitative energetics analysis shows that the rate reduction is attributable to a decrease in the second-order rate constant for the cyclization reaction, which adds 3.7 and 6.5 kcal/mol of activation energy to the respective reactions mediated by the complex with the oxyanion linker. Secondly, we have investigated a series of dinuclear Zn(II) complexes that incorporate various substituents including hydrophobic and hydrogen-bonding ones. Analysis of the data at the pH optimum for each reaction indicates that the presence of the H-bonding groups and alkyl groups provides similar increases (at least an order of magnitude) of the kcat terms over the unfunctionalized complex. There is also no clear trend that H-bonding groups or the alkyl groups provide stronger binding to the substrate than the parent complex. We also describe here the preparation and kinetic analysis of a series of solid supported transition metal catalysts for the cleavage of P=O chemical warfare simulants and P=S pesticides. We report a kinetic study of a 1,10-phenanthroline:Zn(II) complex immobilized on macroporous polystyrene which is capable of accelerating the cleavage of G-agent and V-agent simulants in methanol at neutral and ambient temperature by up to one hundred thousand-fold. The materials are recoverable and can be recycled at least ten times. We have also devised a methodology for simple immobilization of an ortho-palladated dimethylbenzylamine complex on macroporous polystyrene and amorphous silica gel. We report the catalyst preparation and a detailed kinetic study of their catalysis of the methanolysis of five P=S pesticides at neutral and ambient temperature. The polymeric catalysts give over billion-fold acceleration compared to the uncatalyzed background reaction at the same pH. / Thesis (Ph.D, Chemistry) -- Queen's University, 2010-11-23 12:18:46.936

A series of SNS ligands have been successfully synthesised and characterised by IR, NMR and MS. The ligands are divided into two groups and represented by the general formulae: 2,6- bis(RSCH2)pyridine [R= methyl, ethyl, butyl, cyclohexyl, phenyl] and bis(RSCH2CH2)amine [R= ethyl, butyl, decyl]. Cobalt complexes of the respective ligands with the general formulae Co[2,6-bis(RSCH2)pyridine]Cl2 and Co[bis(RSCH2CH2)amine]Cl2 were synthesised and characterised by IR, elemental analysis and X-ray crystallography (for selected complexes). Thus, to investigate the electronic and steric effects of the ligand structure on the chemistry and reactivity of the complexes, the substituents bonded to the two sulfur donor atoms were sequentially varied and two different nitrogen sources were chosen. Crystal structures of Co[2,6- bis(CH2SCH2)pyridine]Cl2 (Ia), Co[2,6-bis(CH2CH2SCH2) pyridine]Cl2 (IIa) and Co[2,6- bis(CH2CH2CH2CH2SCH2)pyridine]Cl2 (IIIa) were obtained. It was found that complex Ia exists as a molecular dimer linked through two chloride bridges resulting in an octahedral geometry around each metal centre, while complexes IIa and IIIa are monomers exhibiting a trigonal bypyrimidal geometry. The complexes were tested as catalysts for the activation of paraffinic C−H bonds towards the formation of oxygenated products: octanol, octanone, octanal and octanoic acid from the substrate n-octane. Gas chromatography was utilised to quantify the products formed and also to calculate the conversion and selectivity of each catalyst system. The catalytic testing revealed that the ketone products were the most dominant with selectivities of ca. 90%. The catalyst that was the most active was Co[bis(CH2CH2SCH2CH2)amine]Cl2 (Ib) with a total n-octane conversion of 23%. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2012.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [239]-246).

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 62-64). Also available in electronic version. Access restricted to campus users.

Thesis (M. S.)--Biomedical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: DeWeerth, Stephen P.; Committee Co-Chair: Ting, Lena H.; Committee Member: Burkholder, Thomas J.; Committee Member: Nichols, T. Richard; Committee Member: Tresch, Matthew C.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 97-106).

Several series of novel diamido, diamino and diimino ligands containing different spacers and heterocyclic donors have been synthesised. The spacers include the flexible biphenyl, the rigid 1,1 O-phenanthroline and various acyclic moieties, while the heterocyclic donors comprise pyridine, imidazole or benzimidazole groups. These ligands have been designed to complex copper and act as biomimetic models of the active site of the enzyme, tyrosinase, and their complexes with copper, cobalt, nickel and platinum have been analysed using microanalytical, IR, UV-Visible and cyclic voltammetric techniques. Attempted reduction of the biphenyl-based diimino ligands resulted in an unexpected intramolecular cyclisation affording azepine derivatives, the structures of which were elucidated with the aid of single crystal X-ray analysis of cobalt and nickel complexes. Computer modelling methods have been used to explore the conformational options of the copper complexes, and to assess the accessibility of the dinuclear copper site to substrate molecules. Computer modelling has also been used, in conjunction with the available analytical data, to visualise the possible structures of selected ligands and complexes. The copper complexes, although predominantly polymeric, were evaluated as biomimetic catalysts using 3,5-di-t-butylphenol and 3,5-di-t-butylcatechol as substrates. Some of the complexes clearly displayed biomimetic potential, exhibiting both phenolase and catecholase activity.

Understanding why fish move the way in which they do has applications far outside of biology. Biological propulsion has undergone millions of years of refinement, far outpacing the capabilities of anything created by man. Research in the areas of unsteady/biological propulsion has been increasing in the last several decades with advances in technology. Researchers are currently conducting experiments using pitching and heaving airfoils, mechanized fish, and numerical fish. However, the surrogate propulsors that are being used in experiments are driven analytically, whereas in this study, a method has been developed to exactly follow the motion of swimming fish. The research described in this thesis couples the image analysis of swimming fish with computational fluid dynamics to accurately simulate a virtual fish. Videos of two separate fish swimming modes were analyzed. The two swimming modes are termed `free-stream swimming' and the `Kármán gait'. Free-stream swimming is how fish swim in a section of water that is free of disturbances, while Kármán gait swimming is how fish swim in the presence of a vortex street. Each swimming mode was paired with two simulation configurations, one that is free of obstructions, and one that contains a vortex street generating D-section cylinder. Data about the efficiency of swimming, power output, and thrust production were calculated during the simulations. The results showed that the most efficient mode of swimming was the Kármán gait in the presence of a Kármán vortex street. Evidence corroborating this has been found in the literature. The second most efficient means of swimming was found to be free-stream swimming in the absence of obstructions. The other two configurations, which are not observed in experiments, performed very poorly in regard to swimming efficiency.

The slippery zone of the carnivorous (animal eating) plants Nepenthes alata located inside the pitcher shows pronounced anti-adhesive properties. Even insects with highly developed adhesive systems cannot adhere to the slippery zone. This zone consists of three hierarchically structured levels. Lunate cells (length scale of several dozens micrometers) as the first level are covered by two waxy layers representing the second and third hierarchical levels. Inspired by the anti-adhesive properties of the slippery zone, artificial surfaces consisting of polymeric monolithic microsphere arrays within the diameter range 0.4 - 90 µm were developed. These microsphere arrays having approximately the same dimensions as the level 1 lunate cells were prepared by a double replication procedure. For preparation of synthetic anti-adhesives, two different designs, polystyrene (PS) microsphere arrays for dry adhesion and porous polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) microsphere arrays for wet adhesion tests, respectively, were investigated. The adhesion measurements showed that such surfaces exhibit pronounced anti-adhesive properties to rigid as well as to sticky and compliant counterpart surfaces. Moreover, cell culturing experiments suggest that surface topographies promote anti-fouling properties. The bioinspired design strategy reported here may provide access to bioinspired surfaces with tailored contact mechanics by simple modifications of straightforward production processes. Furthermore, the results presented here may improve understanding of the contact mechanics of biological models.