Physical Sciences and Mathematics Commons^™

Vibrational Imaging At The Nanoscale: Surpassing The Diffraction Limit Using Tip-Enhanced Raman Spectroscopy, Farshid Pashaee

Electronic Thesis and Dissertation Repository

A deep understanding of the chemical composition of surfaces, interfaces or nanoscale structure with a high spatial resolution is an important goal in nanoscience and nanotechnology. Structural information can be collected using a variety of high spatial resolution techniques such as atomic force microscopy (AFM), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), or transmission electron microscopy (TEM). Nevertheless, these methods do not offer molecular information such as vibrational spectroscopy techniques that allow one to collect molecular or lattice vibrations yielding to a precise picture of the molecular interactions in bulk materials as well as in surfaces and interfaces. Unfortunately …

Solvothermal Synthesis And Characterization Of Cuins2, Cuinse2 And Agins2 Nanoparticles From Single Source Precursors, Xuzhao Zhao

Electronic Thesis and Dissertation Repository

Nanoscale semiconductors have emerged as alternative candidates for the absorber layer in solar cells. Group 11-13-16 semiconductors have received a lot attention because of their direct band gap energies, high absorption coefficients and environmental friendly nature. To date, CuInS₂, CuInSe₂ and AgInS₂ semiconductors are three of the main ternary nanomaterials investigated. Besides the application in solar cells, these nanoscale semiconductors can also be applied in areas such as biosensors and hydro catalysis.

However, it is often challenging to prepare small-sized nanoparticles with uniform size and shape, especially for large scale production. In this thesis, the synthesis …

High Pressure Studies Of Nanostructured Tio2 And Li4ti5o12 Using Raman Spectroscopy And Synchrotron X-Ray Radiation, Fengping Xiao

Electronic Thesis and Dissertation Repository

Nanomaterials have been extensively studied due to their distinctive properties such as surface effect, small-size effect and quantum size effect. In recent year, investigations of the structural and phase transformations of nanomaterials under high pressure are receiving increasing attentions. In addition to composition and synthetic routes, pressure provides a clean way to adjust interatomic distance and hence affect the crystal structure and thus properties of the nanostructured materials.Two nanomaterials (i.e. TiO₂ and Li₄Ti₅O₁₂) with different morphologies are studied in this thesis.

In part I, the high-pressure behaviours of four hydrothermal synthesized 1D rutile …

The Influence Of Alloying Elements On The Crevice Corrosion Behaviour Of Ni-Cr-Mo Alloys, Nafiseh Ebrahimi

Electronic Thesis and Dissertation Repository

To enhance its corrosion resistance in aggressive media, Ni is alloyed with various amounts of Cr and Mo along with small amounts of other alloying elements such as W, Cu, and Fe. While the resulting alloys (known as Ni superalloys) show excellent passive behaviour, the function of individual alloying elements in resisting localized corrosion processes, in particular crevice corrosion is not fully understood. This study focuses on the electrochemistry and corrosion of a series of Ni-Cr-Mo (W) alloys with various Cr and Mo contents. Several electrochemical and surface characterization techniques were used to investigate the role of major alloying elements …

The Corrosion Behaviour Of Cu In Irradiated And Non-Irradiated Humid Air, Balsam Ibrahim

Electronic Thesis and Dissertation Repository

The present management scenario for the permanent disposal of high level nuclear waste in Canada is to seal it in metallic containers and bury it in a deep stable geologic repository. For thick-walled containers radiation fields on the outside of the container would have a negligible influence on container corrosion. However, to overcome fabrication issues and to reduce costs, steel containers with a thin outer copper coating are being designed making a reassessment of the influence of gamma radiation on container corrosion a potential licensing requirement.

The behaviour of Cu in an aerated vapour phase environment in equilibrium with condensed …

Mass Spectrometric Analyses Of Surface Proteins From Candida Albicans After Treatment With Histatin 5, Shirley Fan

Electronic Thesis and Dissertation Repository

Current drug therapies have lost their effectiveness in controlling the fungal species known as C. albicans; therefore, the need for newer drugs becomes crucial. Histatin 5 (Hst 5), a naturally occurring peptide found in the oral cavity, has demonstrated strong effects on controlling candidiasis. Here, we have proposed that the adhesion of cells through surface proteins is an important process. To allow the analysis of surface proteins, the concept of on-whole cell tryptic digestions were developed. This on-target approach allows for isolation of the peptides of interest, while greatly reducing digestion times.

To study the effects of Histatin 5 …

Optimization Of Cu2znsns4 Nanocrystal Composition And Thin Film Fabrication For Photovoltaic Applications, Saghar Khoshmashrab

Electronic Thesis and Dissertation Repository

In this work Cu2ZnSnS4 (CZTS) nanocrystals (NCs) were prepared via a solvothermal, one-pot method. Given that the composition affects the electronic properties of this p-type semiconductor, comparative compositional analysis was done from various designed and synthesized analogues. EXAFS studies indicated that the stoichiometries with lower Cu-contents (Cu Sn+Zn

The effects of Cu were further studied, using Cu-poor and Cu-stoichiometric NCs.This time the precursor content of Zn was also increased to yield samples with Zn rich compositions. NCs in which the Cu concentration was below stoichiometric (Cu1.8Zn1.1Sn1.0S4.8) were more crystalline and yielded a higher photoresponse (~53 μA/cm2).

The compositionally optimized CZTS …

Dynamic Studies Of Guest Molecules In Metal-Organic Frameworks Using Solid-State Nmr, Yuanjun Lu

Electronic Thesis and Dissertation Repository

Metal-organic frameworks (MOFs) are a new class of porous materials that possess large three-dimensional voids in their structures. In this work, Solid-state NMR (SSNMR) is used to examine the dynamics of guest molecules at various temperatures in MOFs that possess different types of channels. Chapter 2 introduces the ¹³CO₂ adsorption behavior in α-Mg formate studied by ¹³C SSNMR in conjunction with molecular dynamic simulation. ¹H-¹³C cross polarization technique has successfully determined the adsorption sites of CO₂ in this type of MOF to be hydrogen atoms. The dynamic analysis detects that at low temperature, …

Reactions Between Zinc Metallothionein And Carbonic Anhydrase, Tyler B. J. Pinter

Electronic Thesis and Dissertation Repository

More than 25% of proteins require metal ion cofactors for structure or function. The interactions between metalloproteins have largely been overlooked, though these interactions ultimately govern metal localization and control metal ion homeostasis. Mammalian metallothionein (MT) is a small, cysteine-rich metalloprotein that binds numerous metal ions per protein strand. Up to seven divalent metals, such as zinc or cadmium, are wrapped into a clustered two-domain structure. This unusually high metal content places MT as an attractive candidate for studying interactions with other metal-binding proteins. This present study investigates the metal transfer reactions between MTs and other metalloproteins, using carbonic anhydrase …

Functional –Esime3 Containing Reagents: From Organo-Polychalcogenolates To Nhc Ligated M-E-Sime3, Mahmood Azizpoor Fard

Electronic Thesis and Dissertation Repository

The reaction of M[ESiMe₃] (M = Li/Na; E = S, Se) with polyorganobromides, has afforded polychalcogenotrimethylsilane complexes Ar(CH₂ESiMe₃)_n: 1,4-(Me₃SiECH₂)₂(C₆Me₄) (E = S, 1; E = Se, 2), 1,3,5-(Me₃SiECH₂)₃(C₆Me₃) (E = S, 3; E = Se, 4) and 1,2,4,5-(Me₃SiECH₂)₄(C₆H₂)(E = S, 5; E = Se, 6). The powerful potential of these complexes as precursor to combine with …

The Development Of Cyclic Rgd Peptides Stabilized Through 99mtc/Re(Co)3+, Aagam Patel

Electronic Thesis and Dissertation Repository

Protein secondary structure can be mimicked by incorporating structural constraints into peptides and this can be facilitated by metal coordination. The objective of this project is to establish a chelation system with a cancer targeting peptide sequence, where the coordination to a metal centre results in a cyclic metallopeptide. Cyclic RGD peptides are antagonists for α_vβ₃ and other integrins, which are present during tumour angiogenesis. Arg-Gly-Asp (RGD) sequence is employed in the peptide backbone, with an un-natural amino acid (3-Pal) and a chelating molecule (pyridyl-triazole, pyta) present on opposite ends of the peptide sequence to form a …

Design And Fabrication Of Integrated Plasmonic Platforms For Ultra-Sensitive Molecular And Biomolecular Detections, Mohammadali Tabatabaei

Electronic Thesis and Dissertation Repository

One of the major challenges in analytical and biological sciences is to develop a device to obtain unambiguous chemical and structural properties of a material or a probe biomolecule with high reproducibility and ultra-high sensitivity. Moreover, in addition to such a high sensitivity, other cases such as minimum intrusiveness, small amounts of analyte, and short acquisition time and high reproducibility are key parameters that can be valued in any analytical measurements. Among the promising methods to achieve such endeavor, plasmon-mediated surface-enhanced spectroscopic techniques, such as surface-enhanced Raman spectroscopy (SERS), are considered as suitable options. Such techniques take advantage of the …

X-Ray Absorption Fine Structure Studies Of Calcium Silicate Hydrate Biomaterials In Drug Delivery, Xiaoxuan Guo

Electronic Thesis and Dissertation Repository

Calcium silicate hydrate (CSH), a new type of bioceramics, has gained significant attention in hard tissue restoration because of their impressive role in the stimulation of osteoblast proliferation and differentiation in vitro. The further development of mesoporous bioceramics opens up new opportunities for drug delivery in hard tissue therapies. In this thesis, interaction mechanisms of drug molecules with CSH of different morphologies and CSH/polymer composites, imaging of drug distributions in CSH carriers in nanoscale, and the biomineralization mechanisms of CSH in vitro during drug release are extensively investigated using X-ray absorption near edge structure (XANES) and scanning transmission X-ray …

In Situ High-Pressure Study Of Metal-Organic Frameworks And Their Performance For Co2 Storage Probed By Vibrational Spectroscopy, Yue Hu

Electronic Thesis and Dissertation Repository

Metal-organic frameworks (MOFs) are an important class of porous materials, owing to their potential applications in a variety of areas, including gas storage, molecular separations, catalysis, sensors and so on. Most importantly, their extraordinary surface areas, tunable pore properties and potential for industrial scale production have made MOFs a promising material for clean energy applications, such as CO₂ storage. The chemical and mechanical stabilities of MOFs play a crucial role in their CO₂ storage performance, which require extreme loading pressures that are far beyond ambient pressure at times. Application of high external pressure (e.g., in gigapascal range) on …

Study Of The Secondary Metabolites Of Black Aspergilli From Canadian Vineyards, Tianyu Qi

Electronic Thesis and Dissertation Repository

Ochratoxin A (OTA) and fumonisin are mycotoxins produced by black Aspergilli that contaminate wine in many countries around the world. Both OTA and fumonisins are possible carcinogens to humans. There is limited data about the occurrence of OTA and fumonisins in Canadian vineyards. Therefore, a survey of the black Aspergilli from 2012-2014 has been conducted. In the mycotoxin study, high performance liquid chromatography-mass spectrometry was used to screen and quantify OTA and fumonisins from both black Aspergilli isolated on artificial media and grape samples. OTA was only detected from one fungal isolate and not on any grapes. Fumonisin B_{2 …}

Self-Assembly And Stimuli-Responsive Properties Of Amphiphilic Self-Immolative Block Co-Polymers, Thomas Mackenzie Gungor

Electronic Thesis and Dissertation Repository

In recent years, degradable polymers have become increasingly researched for their applications in drug delivery systems, adhesives, and tissue engineering. Self-immolative polymers (SIPs) are of particular utility due to predictable end-to-end backbone depolymerization after a stimuli-responsive end-cap cleavage. There are examples of incorporating a hydrophobic SIP into an amphiphilic block-copolymer, followed by self-assembly in aqueous media forming various nanoparticle morphologies. However, their self-assembly behaviour has not been described in detail, and there are no general synthetic methods that allow for their synthesis with good control over the relative hydrophilic block ratio, the major factor controlling their morphology. This thesis presents …

Metal-Ligand Cooperative Catalysis And Methods For Metal Removal From Organic Transformations, John-Paul J. Bow

Electronic Thesis and Dissertation Repository

Organometallic catalysis has revolutionized the synthesis of complex organic molecules. Methods for C-C, C-X and C-H bond formation and cleavage are exploited throughout the areas of fine chemicals synthesis, with major applications for pharmaceuticals. This situation raises duel challenges: 1) high-performance catalysts for environmentally and economically sustainable synthesis and 2) efficient methods of catalyst (i.e. metal) removal must be identified. This work tackles both of these areas. The highly tunable cooperative P^R₂N^R'₂ ligands have been implemented for the first time for catalytic organic transformations. I show that [Ru(Cp)(P^tBu₂N^Bn₂)(MeCN)][PF_{6 …}

Mechanistic Studies Of Donor-Acceptor Cyclopropanes, Tristan Chidley

Electronic Thesis and Dissertation Repository

Cyclopropane 1,1-diesters have been investigated as a source of donor-acceptor cyclopropanes, providing an understanding of the mechanism of reaction between these cyclopropanes and nitrosoarenes, as well as azo dicarboxylates. Cross-over experiments have been utilized to provide key pieces of experimental evidence that help generate a theoretical model of the reactions. By understanding these reactions with precision, the avenue to expand the reaction scope and develop other useful reactions is opened up. This allows the chemistry to be better utilized, providing easier access to important molecules when needed, and contributes to advancing the field of synthetic organic chemistry.

In addition, cyclobutane …

Stimuli-Responsive Polymersomes And Surface Functionalized Dendrimersomes: Platforms For Biomedical Applications, J Trevor Mcintosh

Electronic Thesis and Dissertation Repository

Amphiphilic block copolymers (BCPs) and dendrimers are known to self-assemble in aqueous solution to form a number of aggregate morphologies. These different architectures are largely a function of the hydrophilic volume or weight fractions of the different components of the polymer system. One possible morphology is a vesicle, also referred to as a polymersome or dendrimersome when BCPs or dendrimers, respectively, are used. Vesicles are multi-functional, supramolecular, bilayer assemblies, whose potential for stimuli-responsiveness and surface functionalization make them promising materials for a variety of biomedical applications. This thesis demonstrates the use of UV-sensitive block copolymers forming photodegradable vesicles, as well …

Coinage Metal Silylphosphido Complexes Stabilized By N-Heterocyclic Carbene Ligands, Bahareh Khalili Najafabadi

Electronic Thesis and Dissertation Repository

N-Heterocyclic carbenes (NHCs) are strong σ-donating ligands and thus, promising candidates for decorating and stabilizing metal-phosphide nanoclusters. While much research has been focused on the coordination of NHC ligands to different coinage metal centers in order to synthesize mononuclear organometallic complexes, their application in nanocluster chemistry has been relatively unexplored. The work described in this thesis involves employment of NHC ligands for stabilizing coinage metal t-butylthiolate and silylphosphido complexes. These complexes are promising molecular precursors for formation of larger NHC-stabilized nanoclusters.

In particular, the ligation of NHCs to [CuS^tBu] and [AgS^tBu] was developed as an …

Computational Studies Of Compressed Diborane And Engineered Narrow-Gap Semiconductors, Amin Torabi

Electronic Thesis and Dissertation Repository

The research contained in this thesis is two-fold: understanding the behavior of diborane under pressure, and engineering wide-gap semiconductors in order to promote their optical eciency. Each of these themes are further explained below.

Diborane (B₂H₆), is a prototypical electron-deficient molecule and has received a great deal of attention in recent years due to its unique and peculiar structure, as well as its potential applications as a hydrogen-storage material. At high pressures, vibrational spectroscopy analysis have revealed several changes in the spectral profile that suggest occurrence of polymorphic transformations; however, the new crystal structures at high …

Field Scale Application Of Nanoscale Zero Valent Iron: Mobility, Contaminant Degradation, And Impact On Microbial Communities, Chris M.D. Kocur

Electronic Thesis and Dissertation Repository

This thesis began by verifying that nanoscale zero valent iron (nZVI) synthesis methods could be scaled up and implemented at the field scale in a safe manner. This led to successful demonstration of nZVI injection and mobility under constant head gravity injection into a contaminated utility corridor in Sarnia, Ontario. Where field studies have fallen short in the past was linking the somewhat qualitative field geochemical parameters to other evidence of nZVI transport. Definitive nZVI detection was elusive in previous field studies due to the highly reactive nature of the particles caused by their high surface area. nZVI was detected …

Strategies For Photochemical And Thermal Modification Of Materials, Sara Ghiassian

Electronic Thesis and Dissertation Repository

The modification of materials/surfaces is central to numerous applications ranging from opto-electronic devices to biomedical implants and drug delivery. Thus, there exists a high motivation for improving the methodologies which can be employed in order to modify surfaces in a selective and efficient fashion. One of the major goals of surface engineering is to control the chemical composition at the material interface. The fine control of the surface properties is a field of intense research as the performance of functional materials is strongly related to the processes and interactions that are occurring at the materials’ interface.

In general, the modification …

Complementary Mass Spectrometry Methods For Characterizing Protein Folding, Structure, And Dynamics, Siavash Vahidi

Electronic Thesis and Dissertation Repository

Proteins are involved in virtually every biochemical process. A comprehensive characterization of factors that govern protein function is essential for understanding the biomedical aspects of human health. This dissertation aims to develop complementary mass spectrometry-based methods and apply them to solve problems pertaining to the area of protein structure, folding and dynamics.

‎Chapter 1 uses fast photochemical oxidation of proteins (FPOP) to characterize partially disordered conformers populated under semi-denaturing conditions. In FPOP, ·OH generated by laser photolysis of H₂O₂ introduces oxidative modifications at solvent accessible side chains. By contrast, buried sites are protected from radical attack. Using …

Hydrogen Exchange Mass Spectrometry For Studying Protein-Ligand Interactions, Modupeola A. Sowole

Electronic Thesis and Dissertation Repository

Hydrogen deuterium exchange (HDX) coupled with mass spectrometry is widely used for probing protein structure and dynamics. Protein-ligand interactions usually induce a reduction in the measured HDX rates an effect that may be ascribed to stabilization of the protein structure. This work aims to improve the general understanding of the changes in HDX patterns associated with ligand binding.

We initially applied HDX for studying differences between oxy-hemoglobin (Oxy-Hb) and aquomet-hemoglobin (Chapter 2). The results show that the α and β subunits respond differently to the oxy to aquomet transition with the heme binding pocket being destabilized in both cases. The …

From Solution Into The Gas Phase: Studying Protein Hydrogen Exchange And Electrospray Ionization Using Molecular Dynamics Simulation, Robert G. Mcallister

Electronic Thesis and Dissertation Repository

Here, we apply Molecular Dynamics (MD) simulations to investigate fundamental aspects of structural mass spectrometry (MS). We first examine microscopic phenomena underlying Hydrogen/Deuterium exchange (HDX). HDX interrogates structural dynamics of proteins by measuring the rate of Deuterium uptake into backbone amides. We perform microsecond MD simulations on ubiquitin to investigate this process. We find that HDX protection often cannot be explained by H‑bonding or solvent accessibility considerations. These findings caution against non-critical use of HDX data in structural contexts. We next use MD to examine the Electrospray ionization (ESI) mechanism of proteins. ESI is a soft ionization technique resulting in …

Using Ion Mobility Spectrometry To Study Protein Conformations In The Gas Phase, Yu Sun

Electronic Thesis and Dissertation Repository

The question whether electrosprayed protein ions retain solution-like conformations remains a matter of debate. One way to address this issue involves comparisons of collision cross sections measured by travelling wave ion mobility spectrometry (TWIMS) with the values calculated for model structures. It is often implied that nanoESI is more conducive for the retention of solution structure than regular ESI. Focusing on four different proteins we demonstrated that collision cross section values and collisional unfolding profiles are virtually indistinguishable under both conditions. Calibration can be challenging because differences in the extent of collisional activation for TWIMS and drift tube calibrant data …

Exploring The Chemistry Of Phosphorus For Photopolymer Applications, Ryan Guterman

Electronic Thesis and Dissertation Repository

Prior to this thesis, phosphorus-containing polymers and photopolymerization represented two distinct, non-overlapping fields of study. This thesis examined the prospect of combining these two approaches to create a system possessing the benefits of both techniques. By exploiting the chemistry of phosphorus, and using photopolymerization as a fabrication method, new materials were developed and assessed for their use in various applications.

Among the many phosphorus compounds that may be used in polymer science, phosphonium salts and primary phosphines were of specific focus. First, highly fluorinated phosphonium monomers were developed to create photopolymerized hydrophobic surfaces. A structure-activity relationship was established, as both …

Exploring The Chemistry Of Η5-Cyclopentadienyl-Cobalt-Η4-Cyclobutadiene Containing Polymers; Synthesis, Properties, And Self-Assembly, Mahboubeh Hadadpour

Electronic Thesis and Dissertation Repository

Metal containing polymers (metallopolymers) bring together the synthetic efficiency and versatility of conventional organic polymers with unique redox, responsive, and catalytic properties of inorganic metals. Over the last decade, metallopolymers have gained increased attention because of their unique physical and chemical properties that arise from the incorporation of metal centers into a polymer. Since the first report on a metallocene-based metallopolymer in 1955, there has been growing interest in this class of material. Ferrocene-based metallopolymers represent the vast majority of metallocene containing polymers in the literature. In 1992, the Manners Group established a major milestone in the field of metallopolymers …

Design, Synthesis, And Reactivity Of Bimetallic Complexes Of Dimethylplatinum(Ii) Containing Ditopic Ligands, Matthew S. Mccready

Electronic Thesis and Dissertation Repository

This thesis describes a study of monometallic and bimetallic dimethylplatinum(II) complexes containing ditopic nitrogen donor ligands. This work details the design and synthesis of side-to-side and cofacial arranged ligands and their respective coordination chemistry. The study of the synthesis, characterization and reaction mechanisms of the various dimethylplatinum(II) complexes is outlined in detail with special emphasis focused on the reactivity of the complexes towards oxidative addition.

The ditopic ligand 6-dppd, 1,4-di(2-pyridyl)-5,6,7,8,9,10-hexahydrocycloocta[d]pyridazine, was observed to coordinate only a single equivalent of a platinum(II) center. The inability to coordinate a second equivalent, even through an assisted bridging atom, is presumed to be due …