Physical Sciences and Mathematics Commons^™

Migration Behaviour Of Discontinuous Buffers In Capillary Electrophoresis During Protein Enrichment, Ting Li

Electronic Thesis and Dissertation Repository

To enrich protein at sub-microliter sample volumes, our group has developed a discontinuous buffer system which consists of an acid and a base inside a capillary. Upon voltage application, the protein moves towards and stacks at the pH junction. Prior to this work, we only focused on the protein enrichment and have not investigated the migration behaviour of various ions in this system. However, it is important to understand the mechanism of the migration of these ions, because the pH junction formation and further the protein enrichment are based on it. In this work, the ion migration patterns at the …

The Multicomponent Synthesis Of Pyrroles From Cylcopropane S Using A One Pot Pd(0) Catalyzed Dehydrocarbonylation Protocol, William J. Humenny

Electronic Thesis and Dissertation Repository

Previous work done by the Kerr group has shown that tetrahydro-1,2-oxazines can be efficiently synthesized using a three component coupling reaction between a hydroxylamine, aldehyde and cyclopropane diester. This affords the desired heterocycle efficiently with a wide variety of substitution. When one esters bears an allyl group a Tsuji dehydrocarbonylation reaction may take place resulting in the formation of a 4,5-dihydro-1,2-oxazine. This motif contains a vinylogously acidic proton which is extremely labile and easily deprotonated. Under basic conditions this proton is removed and consequently the N-O bond is cleaved and subsequent condensation occurs forming a pyrrole. Using a sequence of …

X-Ray Absorption Fine Structure And X-Ray Excited Optical Luminescence Studies Of One-Dimensional Nanomaterials, Lijia Liu

Electronic Thesis and Dissertation Repository

One dimensional nanomaterials have attracted extensive attention in recent years due to their superior electrical, optical, mechanical and chemical properties compared to their bulk counterparts. In this thesis, electronic structure and optical properties of three types of nanomaterials are investigated using synchrotron based X-ray absorption spectroscopy: X-ray absorption fine structure (XAFS) and X-ray excited optical luminescence (XEOL).

Si nanowire arrays are synthesized using electroless chemical etching, and coated with platinum and gold nanoparticles. The interaction between metal nanoparticles and the nanowire substrate is investigated using X-ray absorption near-edge structure (XANES). The luminescence properties of thermally oxidized Si nanostructures, such as …

High-Pressure Study Of Molecular Solids And 1d Nanostructures By Vibrational Spectroscopy And Synchrotron X-Ray Diffraction, Zhaohui Dong

Electronic Thesis and Dissertation Repository

Pressure plays a critical role in regulating the structures and properties of materials. Since Percy Bridgeman was recognized by the 1946 Nobel Prize for his contribution to high-pressure physics, high-pressure research as an interdisciplinary area has attracted extensive attentions. Nowadays, the high-pressure research involves broad frontier areas, such as chemistry, physics, biology, material and earth science. For instance, brand new classes of inorganic materials of unusual stoichiometries and crystal structures, with wide range of optical, mechanical, electronic and magnetic properties, have been produced at high pressure. Pressure-induced structural transformations between crystalline and amorphous materials, as well as among insulators, conductors …

The Synthesis And Reactivity Of New Pnictogen(Iii) Cations, Allison L. Brazeau

Electronic Thesis and Dissertation Repository

Chelating nitrogen based ligands are well known for their use with transition metals while their chemistry with p-block elements has been relatively underdeveloped. This thesis examines the structure, bonding and reactivity of group 15 elements supported by a pyridyl tethered 1,2-bis(imino)acenaphthene (“clamshell”) and various homo- and heteroleptic guanidinate frameworks.

The unique “clamshell” ligand contains a pendant Lewis base and has been used to support N-heterocyclic phosphenium and arsenium cations. Reactivity studies with the phosphorus analogue demonstrate the ability of the ligand to act as a Lewis base, while the phosphorus centre provides a Lewis acidic site, showing the amphoteric …

Complementary And Self-Complementary Hydrogen Bond Double Helical Complexes, Bhanu P. Mudraboyina

Electronic Thesis and Dissertation Repository

The design of artificial or synthetic strands that self-assemble to form double-helical complexes have been of great interest to chemists and researchers since the discovery of the double helical DNA structure in 1953 by Watson and Crick. Most of the complexes were self-complementary double-helical homodimers and while few heterodimer complexes are also known. The present thesis describes the design, synthesis and characterization of complementary and self-complementary hydrogen bond arrays built from heterocycles such as pyridine, thiazine dioxide and indole connected in different sequences. The sequence-based stabilities, insolubility issues, substitution and preorganization effects in these arrays have been studied in detail. …

Heme Binding And Transfer In The Isd Heme Scavenging Pathway Of Staphylococcus Aureus, Michael T. Tiedemann

Electronic Thesis and Dissertation Repository

The antibiotic resistant bacterium Staphylococcus aureus is a significant problem in hospitals and communities worldwide. Survival of the bacterium in the host is reliant on iron scavenging. Staphylococcus aureus has adopted specialized mechanisms for scavenging iron from the host. The cell wall and membrane-associated iron regulated surface determinant (Isd) proteins allow Staphylococcus aureus to scavenge iron from the heme in hemoglobin. There are nine Isd proteins (IsdH, IsdB, IsdA, IsdC, IsdE, IsdD, IsdF, IsdG and IsdI) located at different depths in the cell wall and membrane. Magnetic circular dichroism (MCD) spectroscopy and electrospray ionization mass spectrometry (ESI-MS) have been used …

Electrohydrodynamic Enhancement Of Heat Transfer And Mass Transport In Gaseous Media, Bulk Dielectric Liquids And Dielectric Thin Liquid Films, Seyed Reza Mahmoudi

Electronic Thesis and Dissertation Repository

Controlling transport phenomena in liquid and gaseous media through electrostatic forces has brought new important scientific and industrial applications. Although numerous EHD applications have been explored and extensively studied so far, the fast-growing technologies, mainly in the semiconductor industry, introduce new challenges and demands. These challenges require enhancement of heat transfer and mass transport in small scales (sometimes in molecular scales) to remove highly concentrated heat fluxes from reduced size devices. Electric field induced flows, or electrohydrodynamics (EHD), have shown promise in both macro and micro-scale devices.

Several existing problems in EHD heat transfer enhancements were investigated in this thesis. …

Kinetics Of O2 Reduction On Oxide-Covered Ni-Cr-Mo Alloys, Xiangrong (Sarah) Zhang

Electronic Thesis and Dissertation Repository

Ni-Cr-Mo alloys exhibit exceptional corrosion resistance and are widely used in chemical processing industries. The reliable performance of these alloys under extreme industrial conditions, are generally attributed to the presence of a passive film on the alloy surface. O₂ reduction is the most likely cathodic process able to sustain metal oxidation (corrosion) in industrial environments. However, the kinetics of O₂ reduction on these oxide-covered alloys has hardly been studied, despite the possibility it may be the rate controlling process for corrosion, especially localized corrosion. The objectives of this research are to characterize the properties of the oxide film …

Structural Motifs Of Novel Metallothionein Proteins, Duncan E K Sutherland

Electronic Thesis and Dissertation Repository

Metallothioneins (MT) are a family of small cysteine rich proteins, which have been implicated in toxic metal detoxification, protection against oxidative stress, and as a metallochaperone. The most well studied member of the family is the mammalian MT, which consists of two domains: a β-domain with 9 cysteine residues, which sequesters 3 Cd²⁺/Zn²⁺, and an α-domain with 11 cysteine residues, which sequesters 4 Cd²⁺/Zn²⁺. The exact functions of MT are unknown but must relate to its metalation status. Several areas that could lead to the assignment of function include 1) the determination …

Solid-State Nuclear Magnetic Resonance Spectroscopy Of Unreceptive Quadrupolar Nuclei In Inorganic Materials, Andre Sutrisno

Electronic Thesis and Dissertation Repository

Preparation and characterization of inorganic materials is a crucial practice because understanding the relationship between structure and property is important for improving current performance and developing novel materials. Many metal centers in technologically and industrially important materials are unreceptive low-γ quadrupolar nuclei (i.e., possessing low natural abundance, low NMR frequencies and large quadrupole moments) and they usually give rise to very broad NMR resonances and low signal-to-noise ratios, making it difficult to acquire their solid-state NMR spectra. This thesis focuses on the characterization of inorganic materials using solid-state NMR (SSNMR) spectroscopy at very high magnetic field of …

Enhancing Raman And Fluorescence Spectroscopies With Nanosphere Lithography Platforms, Shabila Fayyaz

Electronic Thesis and Dissertation Repository

Localized surface plasmon resonance (LSPR) is of particular interest to enhance the limit of detection for spectroscopic techniques such as Raman and fluorescence via a surface enhancement from metallic nanostructures. In this study, using nanosphere lithography (NSL) technique, a series of gold nanostructures over glass surfaces are prepared. These nanostructures are used to record the surface enhanced Raman scattering (SERS) spectrum of benzenethiol and azobenzene thiol and the vibrational modes are compared to literature. Once protected with an ultrathin layer of SiO₂, the gold nanostructures are investigated using scanning confocal fluorescence microscopy to detect the fluorescence from a …

Synthesis Of Self-Immolative Monomers And Their Applications In Polymeric Materials, Matthew A. Dewit

Electronic Thesis and Dissertation Repository

Self-immolative spacers are a unique class of molecules employed in a variety of applications, particularly in the biomedical field. Most commonly, they are molecules containing two reactive termini with a capping group at one terminus and a substrate of interest at the other. Upon removal of the capping group, the spacer undergoes an intramolecular reaction that results in its removal from the molecule and liberation of the substrate. These spacers have been extensively studied in monomeric form within prodrugs, as well as to form dendrimers that have been used for applications such as signal amplification, molecular logic gates and amplified …

Progress Towards The Total Synthesis Of Amphidinolide C, Nicholas A. Morra

Electronic Thesis and Dissertation Repository

A second generation catalyst for the Mukaiyama oxidative cyclization for the formation of trans-THF rings is described. Co(nmp)₂, displays increased stability to the reaction conditions, resulting in lower catalyst loadings, lower reaction temperatures, and significantly higher purity and yields of the products. Three procedures have been developed with this new water-soluble catalyst that greatly simplifies the post-reaction purification, making this procedure the premier method of forming trans-THF rings.

This new catalyst has been applied towards the total synthesis of the potently bioactive macrocycle, Amphidinolide C. Herein we report the successful synthesis of several fragments of the …

Synthesis Of (±)-Quebrachamine, Tetrahydroisoquinocarbazoles, And Progress Towards Biselide A And E, Barbora Morra

Electronic Thesis and Dissertation Repository

A variety of methodologies developed in our research group have inspired the three separate projects reported. First, the total synthesis of (±)-quebrachamine was performed in 13 steps and 17.8% overall yield. Highlights of the synthesis include an efficient preparation of a functionalized indole core via a [3+2] annulation cycloaddition reaction between a functionalized nitrile and donor-acceptor cyclopropane and a photo induced 9-membered ring closure.

Secondly, we have reported the most efficent and highest yielding route to several tetrahydroisoquinocarbazoles, where the core was prepared in six steps from tryptophol in 51% overall yield. This work highlights for the first time the …

Scanning Probe Microscopy Studies Of The Properties Of Conducting Polymers, Kevin D. O'Neil

Electronic Thesis and Dissertation Repository

Electronically conducting polymers (ECPs) have been growing in interest as important materials for a variety of different applications such as charge storage devices and photovoltaics. However, in all of these applications, the performance of conducting polymers are strongly dependent upon their local properties such as morphology, local conductivity and carrier mobility, local chemical composition, etc. All polymer materials feature a distribution of these parameters and therefore, they are considered heterogeneous. In this work, we use atomic force microscopy (AFM) and its related techniques such as current-sensing AFM (CS-AFM), Kelvin probe force microscopy (KFM) and phase imaging (PI-AFM) to directly investigate …

Miniaturized Fractionation And Purification Of Analytes Of Interest In Complex Mixtures: Protein Enrichment And Purification With Capillary Electrophoresis And Identification Of Pesticide Chemicals In Bio-Oils, Christina J. Booker

Electronic Thesis and Dissertation Repository

The ability to isolate and detect an analyte of interest is vital for many different facets of life today, from disease detection to environmental safety. The goal of the method development discussed within this thesis is to isolate and identify unique analytes from complex matrices and to do so in a scaled down approach. Removal of an analyte from a diverse background of molecules is often required for successful detection and determination of analyte properties. As well, many samples are only available at low volumes and at trace levels so miniaturized techniques that only require small sample volumes are designed …

Syntheses, Hydrogen Bonding, And Metal Coordination Studies Of New Ferrocene Peptide Conjugates, Craig D. Colquhoun

Electronic Thesis and Dissertation Repository

The main goal of the research was the synthesis of new ferrocene peptideconjugates, to study the role of hydrogen bonding interactions, and the coordinationproperties of these systems. Ferrocene peptide conjugates have been extensivelystudied as models of protein secondary structures. Of particular interest weredisubstituted ferrocene derivatives such as ferrocene dicarboxylic acid, which have beenshown to be important in the design of peptide mimics. The inter-ring spacing betweentwo cyclopentadienyl rings in ferrocene has shown to be appropriate for forminghydrogen bonds between conjugated peptide chains, which are attached to the twocyclopentadienyl rings. Inter-ring spacing has proven to be of great importance for theformation …

Transition Metal Complexes With Reactive Trimethylsilylchalcogenolate Ligands: Precursors For The Preparation Of Ternary Nanoclusters, Chhatra Bahadur Khadka

Electronic Thesis and Dissertation Repository

The Co²⁺ and Mn²⁺ complexes (N,N´-tmeda)Co(ESiMe₃)₂ (E = S, 1a; E = Se, 1b), (3,5-Me₂C₅H₃N)₂Co(ESiMe₃)₂ (E = S, 2a; E = Se, 2b), [Li(N,N´-tmeda)]₂[(N,N´-tmeda)Mn₅(μ-ESiMe₃)₂(ESiMe₃)₄(μ₄-E)(μ₃-E)₂] (E = S, 3a; E = Se, 3b), [Li(N,N´-tmeda)]₂[Mn(SSiMe₃)₄] (4), [Li(N,N´-tmeda)]4[Mn₄(SeSiMe₃)₄(μ_{3 …}

Investigating Interfacial Reactions Of Silver-Containing Films Using Novel Methods, Sarah Danielle Pretty

Electronic Thesis and Dissertation Repository

This thesis presents work on the mechanism and kinetics of the surface film reactions involving the conversion of aqueous species on solid surfaces, and specifically, the reactions of iodide and bromide on silver oxide on silver substrate. These reactions provide a method of immobilizing unwanted halides and are particularly suited to control of hazardous radioactive iodine. Potential applications of this research include nuclear reactor safety and post-accident radioiodine management, and the safe production and use of the medical isotope ¹³¹I.

The aqueous-solid conversion of reaction Ag₂O with X^-(aq) to form AgX on a Ag substrate …

Reactivity Of Dimethylplatinum (Ii) Complexes, Muhieddine A. Safa

Electronic Thesis and Dissertation Repository

This thesis describes a study of dimethylplatinum(II) and dimethylplatinum(IV) complexes containing bidentate nitrogen donor ligands. This work deals with oxidative addition, and reductive elimination chemistry, and it focuses on synthesis, characterization, and reaction mechanisms in studies of these complexes.

The compound [PtMe₂(bpe)], bpe = 1,2-bis(2-pyridyl)ethane, is easily oxidized to give octahedral organoplatinum(IV) complexes and the subsequent chemistry is profoundly influenced by the accompanying strain induced in the 7-membered Pt(bpe) chelate ring. On reaction of [PtMe₂(bpe)] with HCl, the initial product [PtHClMe₂(bpe)] undergoes reductive elimination of methane to form [PtClMe(bpe)]. In contrast, methyl …

Structure And Dynamics Of The Membrane Protein Bacteriorhodopsin Studied By Mass Spectrometry, Yan Pan

Electronic Thesis and Dissertation Repository

Membrane proteins continue to represent a major challenge for most analytical techniques. Using bacteriorhodopsin (BR) as model system, this work aims to develop mass spectrometry (MS)-based approaches for exploring the structure, dynamics and folding of membrane proteins.

As the first step, BR in its native lipid environment was exposed to hydroxyl radicals, which were produced by laser photolysis of hydrogen peroxide. It was found that the resulting methionine (Met) labeling pattern was consistent with the known BR structure. This finding demonstrates that laser-induced oxidative Met labeling can provide structural information on membrane proteins. In subsequent experiments, the effects of different …

Electronic And Magnetic Excitations In Graphene And Magnetic Nano-Ribbons, Maher Zakaria Ahmed Selim

Electronic Thesis and Dissertation Repository

The discovery of graphene - a 2D material with superior physical properties - in 2004 was important for the intensive global research to find alternatives to three-dimensional (3D) semiconductor materials in industry. At the same time there have been exciting advances for 2D magnetic materials on the nanometer scale. The superior properties of graphene are mainly attributed to its crystal structure and its relatively short-range interactions. These properties show that natural and artificial 2D materials are promising for new applications.

In this thesis we have carried out a comprehensive investigation of the effects of the 2D lattice structures, the roles …

Development Of Single And Multimodality Imaging Probes For Pet, Spect And Fluorescence Imaging, Babak Behnam Azad

Electronic Thesis and Dissertation Repository

This dissertation is in an integrated format discussing three major projects centered around probe development. In the first project, novel metal-chelated and fluorinated GLP-1 derivatives were prepared all containing D-Ala-8, a modification known to improve resistance towards degradation by dipeptidyl-peptidase IV. The effect of increased distance between DOTA and the peptide chain was investigated using a spacer, in order to reduce steric effects imposed by DOTA. Placement of linker and DOTA moieties were varied within the GLP-1 sequence to test for optimal metal-complex location. Binding affinity of peptide derivatives was determined in vitro with CHO/GLP-1R cell line and shown to …

Uncovering New Bonding Motifs: The Synthesis Of Chalcogen And Phosphorus Complexes Supported By Nitrogen Based Ligands, Caleb D. Martin

Electronic Thesis and Dissertation Repository

The chemistry of the main group elements with nitrogen based ligands has been an area that has received little attention in comparison to transition metals. The preliminary investigations have focused on groups 13 and 14 revealing new bonding motifs and interesting reactivity. This has motivated us to synthesize group 15 and 16 derivatives in new bonding arrangements capable of activating small molecules.

In pursuit of isolating such species, the reactivity of sulfur dichloride and “S(OTf)2” with a series of diazabutadiene (DAB) ligands was explored. The substitution on the ligand was extremely influential on the outcome of the reaction. Alkyl groups …

Molecular Dynamics Simulations Of Charged Nanodroplets, Elias Ahadi

Electronic Thesis and Dissertation Repository

Charged nanodroplets represent a fascinating research area due to their unique dynamics and physical properties. These nanodroplets play a key role in electrospray mass spectrometry (ESI-MS), which is a method for analyzing organic/inorganic molecules as well as proteins and other biomolecular species. The mechanism whereby these analytes are transferred into the gas phase as intact ions remains incompletely understood. Two competing models have been proposed to explain the process, the charged residue model (CRM) and the ion evaporation model (IEM). Under the CRM, evaporation of the droplet proceeds until dryness, at which point the analyte ion is left behind. Under …

Rational Design And Advanced Fabrication Of Metallic Nanostructures For Surface-Enhanced Raman Spectroscopy, Betty Cristina Galarreta

Electronic Thesis and Dissertation Repository

One of the main challenges in analytical science and technology is to develop devices that provide unambiguously the chemical nature of the material of interest with the minimum intrusiveness, the smallest amount of analyte, and the shortest acquisition time. Among the promising methods for such purpose, optical spectroscopy such as surface-enhanced Raman scattering is considered a suitable option. This spectroscopic technique takes advantage of the interaction between an optical field and metallic nanostructures to magnify the electromagnetic field in the vicinity of the nanostructure, resulting in an amplified signal of the vibrational fingerprints of the adsorbed molecules onto the metallic …

Strategies For The Thermal And Photochemical Modification Of Gold Nanoparticles (Aunps) And The Fabrication Of Aunp Hybrid Materials, Hossein Ismaili

Electronic Thesis and Dissertation Repository

Among the existing approaches for the functionalization of the gold nanoparticle (AuNP), a direct interfacial organic reaction of terminal functional groups exposed on the surface of template nanoparticles with various reactants has been shown as a promising strategy to incorporate desired functionality onto the AuNP monolayer. In our own attempts to extend the types of reactions that can be utilized for efficient interfacial modifications of AuNPs, we examined uncatalyzed Huisgen 1,3-dipolar click-type cycloaddition of azide-modified AuNPs to terminal alkynes. These particular reactions were found to be generally too slow to be useful at ambient temperatures but it was shown that …

X-Ray Photoelectron Spectroscopy Studies On The Oxidation Processes Of Nickel, Chromium And Their Alloys, Bradley P. Payne

Electronic Thesis and Dissertation Repository

The reaction of polycrystalline Ni metal surfaces with low pressures (~ 130 Pa) of O₂ gas or H₂O vapour produced thin defective nickel oxide films containing both Ni²⁺ and Ni³⁺ species at 25^oC and 300^oC. Exposure of Ni metal samples to H₂O vapour resulted in a much slower reaction rate when compared to similar doses of O₂ gas. This difference was attributed to a slower place exchange with a surface hydroxyl (OH (ads)) intermediate compared to that of an adsorbed oxygen atom (O (ads)). This OH (ads) species …

Double Helical Hydrogen-Bonded Aaa-Ddd Complexes And Supramolecular Polymers, Hong-Bo Wang

Electronic Thesis and Dissertation Repository

The design and characterization of linear oligomers that self-assemble into double helical structures has been a subject of interest to chemists since the elucidation of the double helix structure of DNA in 1953. Transition metal templates have been widely used in the construction of artificial double helical complexes from linear multidentate ligands. The use of other non-covalent interactions as the driving force in the self-assembly of these types of complexes is less common. Aromatic stacking interactions, anion templates, and salt-bridges have all been applied in this context. The great majority of these investigations have been concerned with the dimerization of …