Chemistry Commons^™

The Influence Of Long-Term Gamma-Radiation And Initially Dissolved Chemicals On Aqueous Kinetics And Interfacial Processes, Pamela A. Yakabuskie

University of Western Ontario - Electronic Thesis and Dissertation Repository

This thesis presents work focusing on the long-term effect of gamma-radiation on aqueous solution kinetics. Ionizing radiation drives the decomposition of water to form both oxidizing (•OH, O₂, H₂O₂) and reducing (•e_aq⁻, •O₂⁻, •H, H₂) chemical species. Over time, these radiolysis products can react with dissolved solutes and participate in interfacial reactions. This can lead to significant changes in the eventual solution redox condition, and gas phase composition, and in certain cases result in the formation of solid species. Understanding the long-term solution kinetics for radiolysis systems is particularly important for the improvement ...

A Comparative Study Of The Oxidation Characteristics Of Two Gasoline Fuels And An N-Heptane/Iso-Octane Surrogate Mixture, Tamour Javed, Ehson F. Nasir, Et-Touhami Es-Sebbar, Aamir Farooq

Dr. Et-touhami Es-sebbar

Ignition delay times and CO, H2O, OH and CO2 time-histories were measured behind reflected shock waves for two FACE (Fuels for Advanced Combustion Engines) gasolines and one PRF (Primary Reference Fuel) blend. The FACE gasolines chosen for this work are primarily paraffinic and have the same octane rating (∼RON = 84) as the PRF blend, but contain varying amounts of iso- and n-paraffins. Species time-histories and ignition delay times were measured using laser absorption methods over a temperature range of 1350–1550 K and pressures near 2 atm. Measured species time-histories and ignition delay times of the PRF blend and the ...

Application Of Colloidal Gas Aphron Suspensions Produced From Sapindus Mukorossi For Arsenic Removal From Contaminated Soil, Soumyadeep Mukhopadhyay Dr, Sumona Mukherjee Ms, Mohd Ali Hashim Dr, Bhaskar Sen Gupta Dr

Soumyadeep Mukhopadhyay Dr

Colloidal gas aphron dispersions (CGAs) can be described as a system of microbubbles suspended homogenously in a liquid matrix. This work examines the performance of CGAs in comparison to surfactant solutions for washing low levels of arsenic from an iron rich soil. Sodium Dodecyl Sulfate (SDS) and saponin, a biodegradable surfactant, obtained from Sapindus mukorossi or soapnut fruit were used for generating CGAs and solutions for soil washing. Column washing experiments were performed in down-flow and up flow modes at a soil pH of 5 and 6 using varying concentration of SDS and soapnut solutions as well as CGAs. Soapnut ...

Targeted Cancer Therapy Systems: An In Silico Study Of Radiohalogenated Ligands In The Estrogen Receptor And The Synthesis Of A Molecular Toolkit For The Fabrication Of Customizable Nanoparticles, Kelton Kerry Barnsley

Chemistry Master's Theses

Chemotherapy is often limited by off-target toxicity and the development of multi-drug resistance in response to treatment. Strategies which reduce off-target toxicity by passively or actively targeting cancer cells may improve the efficacy of chemotherapy. Herein, two projects relating to targeted therapy are described. In the first project, the binding modes of 1,1-bis(4-hydroxyphenyl)-2-phenylethylenes (THPEs), a class of synthetic estrogens previously developed by our group, in the human estrogen receptor alpha-ligand binding domain were studied using molecular modeling programs YASARA AutoDock and Schrodinger Glide. The results were internally consistent and supported the observation that a bromine or iodine ...

Development Of Methods For The Analysis Of Protein Post-Translational Modifications: Isoaspartic Acid And Protein Crosslinking, Min Liu

Chemistry Dissertations

Analysis of protein posttranslational modifications (PTMs) plays pivotal roles for the understanding of their biological importance. Isoaspartic acid (isoAsp) as the smallest PTM is observed in vivo and in vitro. No mass difference and subtle difference in physiochemical property between isoAsp and Asp pose a great challenging for sensitive detection and ambiguous location of isoAsp site in complex samples. A novel assay of isoAsp by exploiting methylation specificity of protein isoaspartate methyltransferase (PIMT) at isoAsp and subsequent ¹⁸O-incorporation during methyl ester hydrolysis is presented for sensitive detection and unambiguous site location of several isoAsp residues in IgG1 (Anal Chem ...

Application Of De Novo Methodology For The Synthesis Of Vineomycins And Oligosaccharides, Yashan Zhong

Chemistry Dissertations

Vineomycin/Fridamycin antibiotics constitute a class of antitumor antibiotics that have been of particular interest to both the synthetic and biological communities. These natural compounds consist of an anthraquinone nucleus bearing one or more sugar moieties via O- or C-glycosidic bond. Acid-catalyzed methanolysis of biologically active Vineomycin B₂ would afford its aglycone Vineomycinone B₂ methyl ester. Our first project developed an effectively convergent route to successfully synthesize Vineomycinone B₂ methyl ester from commercially available anthrarufin. The key steps of the synthesis included Sharpless dihydroxylation, regio- and stereoselective Coates carbonylation, and Lewis acid catalyzed C-glycosylation.

In ...

Exploring The Reactivity Of Donor-Acceptor Cyclopropanes And The Synthesis Of (+/-)-Quebrachamine, Huck K. Grover

University of Western Ontario - Electronic Thesis and Dissertation Repository

The development and utility of cyclopropanes is an ever-growing field within organic chemistry. In particular, donor-acceptor cyclopropanes have been used in a vast array of methods to access a variety of different hetero and carbocyclic molecular scaffolds. Recently, we have developed a Zn(NTf2)2 catalyzed tandem reaction consisting of a nucleophilic ringopening of 1,1-cyclopropanediesters by 2-alkynyl indoles followed by a Conia-ene ring closure, resulting in the efficient one-step synthesis of tetrahydrocarbazoles. These adducts may be further elaborated to carbazoles. The scope and limitations of this method were determined along with a mechanistic study into the function of the ...

Bidentate Ferrocenyl-Dithiol Reagents For Nanocluster Surface Functionalization, Yiyi Liu

University of Western Ontario - Electronic Thesis and Dissertation Repository

Previous work using monodentate ferrocenyl-chalcogen reagents for nanocluster surface functionalization has indicated an effective way to involve ferrocene moieties onto the surface of these frameworks. However, the abilities of the large polynuclear nanocluster with ferrocene rich surface to form crystalline materials suitable for single crystal X-ray analysis proved to be limited. New bidentate ferrocenyl-chalcogen reagents have been synthesized and characterized in order to probe their ability in this case.

The preparation of new bidentate ferrocenyl chalcogen reagents 1,1’-fc(C{O}OCH₂CH₂SH)₂ (fc = ferrocenyl) and 1,1’-fc(C{O}NHCH₂CH_{2 ...}

Scale-Up Methodology For Bench-Scale Slurry Photocatalytic Reactors Using Combined Irradiation And Kinetic Modelling, Patricio J. Valades Pelayo

University of Western Ontario - Electronic Thesis and Dissertation Repository

The present study focuses on developing a predictive methodology to scale-up a slurry annular photoreactor using a TiO₂ Degussa P25 from the bench-scale to a pilot-plant scale. The bench-scale photoreactor is a Photo-CREC-Water II, a 2.65 L internally-irradiated slurry annular photocatalytic reactor. The pilot-plant scale photoreactor is a Photo-CREC Water Solar Simulator, a 9.8 L pilot-plant photoreactor, externally irradiated by eight lamps.

The adopted methodology allows the independent validation of radiative and kinetic models avoiding cross-correlation issues. The proposed approach involves two Monte Carlo methods, to model the Radiative Transfer Equation (RTE) inside each photoreactor. With this ...

Analysis Of Drug Interactions With Lipoproteins By High Performance Affinity Chromatography, Matthew R. Sobansky

Student Research Projects, Dissertations, and Theses - Chemistry Department

High density lipoprotein (HDL), low density lipoprotein (LDL), and very low density lipoprotein (VLDL) are lipoproteins previously shown to bind many basic and neutral hydrophobic drugs in serum. These interactions impact the distribution, delivery, metabolism, and excretion of drugs and are important in determining drug activity, pharmacokinetics, and toxicity in the human body. Information about drug-lipoprotein interactions and the strength of these interactions can be useful in determining the distribution of drugs following administration.

The research presented in this dissertation uses high performance affinity chromatography (HPAC) and packed columns to study binding of the drug propranolol to immobilized lipoproteins such ...

A Novel Method For Confirming The Presence Of Volatile Reduced Sulfide Compounds Via Inductively Coupled Plasma-Optical Emission Spectroscopy, Krystal Lynne Parker

Master's Theses

Millions of dollars in destruction in the past decade have resulted from the use of Chinese drywall in homes. There are also potential health hazards related to this corrosive material. As such, it is important to find a way to identify Chinese drywall. Drywall can be tested for certain markers, such as strontium, sulfur, and carbonates to identify it as corrosive Chinese drywall. The laboratory preparation and analysis should be efficient and cost effective. The methods previously used, such as an X-ray fluorescence gun have had issues with getting a proper reading due to the layers of other materials found ...

Development And Application Of Combined Quantum Mechanical And Molecular Mechanical Methods, Rui Lai

Student Research Projects, Dissertations, and Theses - Chemistry Department

Compromising of computational cost and accuracy, combined quantum mechanical and molecular mechanical (QM/MM) methods are practical methods for studying large molecular systems. The use of induced dipole polarizable force fields can significantly improve the accuracy of MM and QM/MM methods. However, induced dipole models tend to overestimate the polarization energy at short interaction distances. Damping functions can be applied to reduce the over polarization. MM-MM damping schemes have been developed to correct the overestimated polarization between MM atoms; QM-MM damping scheme has not been developed. In this thesis, a QM-MM damping scheme is developed for the damping of ...

Utilization Of Aqueous Raft Prepared Copolymers To Improve Anticancer Drug Efficacy, Andrew Christopher Holley

Dissertations

The advent of controlled radical polymerization (CRP) techniques, along with advancements in facile conjugation chemistry, now allow synthetic tailoring of precise, polymeric architectures necessary for drug/gene delivery. Reversible addition- fragmentation chain transfer (RAFT) polymerization and its aqueous counterpart (aRAFT) afford quantitative control over key synthetic parameters including block length, microstructure, and placement of structo-pendent and structo-terminal functionality for conjugation of active agents and targeting moieties. The relevance of water-soluble and amphiphilic (co)polymers synthesized by RAFT for in vitro delivery of therapeutics in biological fluids is an especially attractive feature. In many cases, polymerization, binding ...

The Identification Of Amino Acids By Interpretation Of Titration Curves: An Undergraduate Experiment For Biochemistry, Cassidy M. Dobson, Nathan S. Winter

Chemistry Faculty Publications

Undergraduate biochemistry students should have great familiarity with titration curves. These curves allow the prediction of protonation states, charges, and isoelectric points. Here we describe an experiment in which students identify four amino acids based on their titration behavior. Students make solutions of each unknown amino acid and monitor the change in pH upon adding aliquots of a strong base. They identify the amino acids based on the shapes of the curves. They annotate the plots with isoelectric points, pKas, buffering regions and the structures of the amino acids.

Microchip Thermal Gradient Gas Chromatography, Anzi Wang

All Theses and Dissertations

Although the airbath oven is a reliable heating method for gas chromatography (GC), resistive heating is needed for higher analytical throughput and on-site chemical analysis because of size, heating rate and power requirements. In the last thirty years, a variety of resistive heating methods were developed and implemented for both benchtop and portable GC systems. Although fast heating rates and low power consumption have been achieved, losses in column efficiency and resolution, complex construction processes and difficulties experienced in recovering damaged columns have also become problematic for routine use of resistively heated columns. To solve these problems, a new resistively ...

Empirical Demonstration Of Environmental Sensing In Catalytic Rna: Evolution Of Interpretive Behavior At The Origins Of Life, Niles Lehman, Tess Bernhard, Brian C. Larson, Andrew J.N. Robinson, Christopher C.B. Southgate

Chemistry Faculty Publications and Presentations

Background

The origins of life on the Earth required chemical entities to interact with their environments in ways that could respond to natural selection. The concept of interpretation, where biotic entities use signs in their environment as proxy for the existence of other items of selective value in their environment, has been proposed on theoretical grounds to be relevant to the origins and early evolution of life. However this concept has not been demonstrated empirically.

Results

Here, we present data that certain catalytic RNA sequences have properties that would enable interpretation of divalent cation levels in their environment. By assaying ...

Photo-Switchable Control Of Membrane Properties Of Liposomes And Biochemical Processes, Andrew Michael Bayer

Doctoral Dissertations

Liposomes are promising agents for drug delivery. They have the ability to encapsulate therapeutic drugs, resulting in decreased toxicity and prolonged circulation time. However, many obstacles to achieving broad utility in liposomal drug delivery still exist, including the ability to control release of therapeutic drugs and modulate surface reactivity. A primary focus of this dissertation involves the development of synthetic photocleavable lipids for controlled release from membranes.

Phosphatidylcholine (PC) is a natural lipid that comprises the majority of structural membranes. It contributes heavily to the formation of lipid bilayers in cell membranes, and modifications to the bilayer can induce membrane ...

Investigations Into Ambient Ionization Mechanisms: Electrospray Ionization And Direct Analysis In Real Time Mass Spectrometry, Stephen Colin Gibson

Doctoral Dissertations

Mass spectrometry (MS) is an important tool for chemical analyses. Despite the MS requirement for generation of analyte gas-phase ions, many ion source designs afford little-to-no fragmentation, allowing characterization of intact molecules. However, this does not assure that detected ions are representative of the analytes’ natural state. Ionization mechanisms are generally complex and rarely fully understood. Fundamental research into these mechanisms provides greater insight into the relationship between solution chemistry and mass spectra. Work herein addresses aspects of two ambient ionization mechanisms: electrospray ionization (ESI) and Direct Analysis in Real Time (DART).

Ions produced by ESI are dispersed into a ...

The Detection Of Peroxynitrite Using 19f Magnetic Resonance Probes, Kevin Bruemmer

Engaged Learning Collection

The following report presents the work done by Kevin Bruemmer for his Engaged Learning project. The 19F magnetic resonance probes 5-uoroisatin and 6-uoroisatin were reacted with ONOO- to yield anthranilic acid derivatives through a novel oxidative decarbonyaltion reaction. Utilizing 19F NMR spectroscopy techniques, the presence of ONOO- can be determined through a chemical shift switching signal. 5-uoroisatin was subsequently used to detect ONOO- in living lung epithelial cells.

Synthesis Of Hydrogenated Thiol-Silanes For Selective Reactions, Macartney Welborn

Engaged Learning Collection

The intention of this experiment is to show the creation of multifunctional thiols from the reaction between various hydrochlorosilanes and mercaptoethanol in an attempt to utilize their distinct properties for practical applications. Multifunctional thiols have many useful applications including use in high-refractive-index lenses, ¹ heavy metal chelation, ² and degradable plastics³. Previous work, ⁵ in our lab has explored a class of reactions key to the synthesis of these compounds: the reaction between methylated chlorosilanes with mercaptoalcohols. We extended this reaction to include hydrogenated chlorosilanes. This allows us to produce multifunctional thiols with an additional functionalizable position at the ...