Chemistry Commons^™

The Effects Of Solution Ph, Temperature And Redox Environment On Corrosion And Oxide Formation On Inconel X-750, Mohsen Bahrami

Electronic Thesis and Dissertation Repository

Nickel-based superalloys have a wide range of applications in different industries due to their exceptional mechanical and corrosion-resistance properties. These alloys are widely employed in the nuclear industry. Inside a nuclear reactor, these alloys are exposed to a continuous flux of gamma-radiation. When exposed to gamma-radiation, water decomposes, resulting in the production of oxidizing and reducing species. These species have a considerable effect on the redox chemistry of the solution, which controls the overall corrosion behaviour of nickel-based superalloys.

Corrosion of metals and alloys involves several elementary steps. A comprehensive understanding of these steps and how they influence each other …

A Computational Study On A Globular Protein And An Intrinsically Disordered Protein, Cecilia Chavez Garcia

Electronic Thesis and Dissertation Repository

We present molecular dynamics (MD) simulations of two protein targets for drug design: Triosephosphate isomerase (TIM) and Methyl CpG binding protein 2 (MeCP2). First, we studied three TIM proteins: TcTIM, TbTIM and a chimeric protein (Mut1). The first two are homologous enzymes with high sequence similarity, albeit different biophysical parameters. The chimeric protein has TbTIM’s sequence and 13 single point mutations, which are sufficient to obtain TcTIM-like behaviour in reactivation experiments. We analyzed the residue interaction networks observed in the all-atom MD simulations, as well as their electrostatic interactions and the impact of simulation length on them. A conserved salt …

Mechanism Of Thermal Protein Aggregation: Experiments And Molecular Dynamics Simulations On The High-Temperature Behavior Of Myoglobin., Yuen Ki Ng, Nastaran N Tajoddin, Pablo M Scrosati, Lars Konermann

Chemistry Publications

Proteins that encounter unfavorable solvent conditions are prone to aggregation, a phenomenon that remains poorly understood. This work focuses on myoglobin (Mb) as a model protein. Upon heating, Mb produces amorphous aggregates. Thermal unfolding experiments at low concentration (where aggregation is negligible), along with centrifugation assays, imply that Mb aggregation proceeds via globally unfolded conformers. This contrasts studies on other proteins that emphasized the role of partially folded structures as aggregate precursors. Molecular dynamics (MD) simulations were performed to gain insights into the mechanism by which heat-unfolded Mb molecules associate with one another. A prerequisite for these simulations was the …

Metal Release From A Biomedical Cocrmo Alloy In Mixed Protein Solutions Under Static And Sliding Conditions: Effects Of Protein Aggregation And Metal Precipitation, Zheng Wei, Valentine Romanovski, Luimar Filho, Cecilia Persson, Yolanda S. Hedberg

Chemistry Publications

Biomedical materials made of cobalt-chromium-molybdenum (CoCrMo) alloys are commonly used in artificial prostheses and dental implants, which are exposed to friction and load. The release of Co, Cr, and Mo from these surfaces is governed by physical and chemical processes. The extent of measured metal release from biomedical CoCrMo alloys into mixed protein solutions may be influenced by protein aggregation and metal precipitation effects. Metal release from, and the surface composition of, a CoCrMo alloy was investigated in physiological relevant solutions (phosphate buffered saline, PBS, with varying concentrations of fibrinogen from bovine plasma and/or bovine serum albumin) at pH 7.3 …

In Situ Study Of Geological Fluid Inclusions Using 23na Nuclear Magnetic Resonance Spectroscopy, Stephen Pilar

Electronic Thesis and Dissertation Repository

²³Na Magic Angle Spinning Solid State Nuclear Magnetic Resonance (MAS SS NMR) spectroscopy has been used to study natural geological samples of halite, fluorite, and quartz to evaluate the efficacy of NMR spectroscopy for in situ fluid inclusion analysis. NaCl calibration standards yielded a strong linear correlation (R²=0.9919) for salinity, albeit only over a ~1 ppm breadth of chemical shift. Fluid inclusions were successfully identified in all three types of minerals studied using MAS NMR. Chemical analysis with Inductively Coupled Plasma -- Mass Spectrometry (ICP-MS) was employed to quantify elemental contaminants in halite samples. Powder X-Ray Diffraction …

Metal Ligand Cooperative Complexes For Acceptorless Dehydrogenation Of Amines, Matthew D. Hoffman

Electronic Thesis and Dissertation Repository

Complexes of the type [M(Cp/Cp*)(MeCN)(P^R₂N^R′₂)]PF₆ (M = Fe, Ru) were synthesized and/or tested towards acceptorless dehydrogenation (AD) of amines. The primary amine benzylamine can undergo AD to form a mixture of products, and a selection of catalysts were employed in an attempt to control product selectivity. As a result, trends in product distribution were observed by modifying the primary and secondary coordination spheres on the catalyst. A new complex, [Fe(Cp)(MeCN)(P^Ph₂N^Ph₂)]PF₆ (3a) was synthesized and characterized and was found to be a completely selective dehydrogenation …

Effects Of Gamma-Radiation On The Evolution Of Copper Corrosion Dynamics In Deep Geological Repository Solution Environments, Lindsay J. Grandy

Electronic Thesis and Dissertation Repository

The Canadian plan for permanent disposal of used nuclear fuel involves a used fuel container (UFC), a carbon steel vessel with a copper coating to provide the corrosion protection. The corrosion conditions for the copper layer of the UFC are expected to involve small, stagnant water volumes, pH values between 6 and 9, and a continuous flux of γ-radiation emitted from the radionuclides trapped in the fuel matrix. While γ-radiation does not affect the copper metal directly, humid air and water will radiolytically decompose into redox-active and acidic species which will be produced at constant concentrations and can alter the …

Characterization Of Ovarian Cancer-Derived Extracellular Vesicles By Surface-Enhanced Raman Spectroscopy., Nina M. Culum, Tyler T. Cooper, Gilles A. Lajoie, Thamara Dayarathna, Stephen H. Pasternak, Jiahui Liu, Yangxin Fu, Francois Lagugne-Labarthet, Lynne Marie Postovit

Chemistry Publications

Ovarian cancer is the most lethal gynecological malignancy, owing to the fact that most cases are diagnosed at a late stage. To improve prognosis and reduce mortality, we must develop methods for the early diagnosis of ovarian cancer. A step towards early and non-invasive cancer diagnosis is through the utilization of extracellular vesicles (EVs), which are nanoscale, membrane-bound vesicles that contain proteins and genetic material reflective of their parent cell. Thus, EVs secreted by cancer cells can be thought of as cancer biomarkers. In this paper, we present gold nanohole arrays for the capture of ovarian cancer (OvCa)-derived EVs and …

The Synthesis And Application Of Polyglyoxylamides, Quinton Ea Sirianni

Electronic Thesis and Dissertation Repository

Self-immolative polymers (SIPs) are a subset of degradable polymers that can be triggered to fully depolymerize with a single stimulus event. This amplifying behaviour makes them ideal for real-world applications including sensors, recyclable plastics, and drug delivery vehicles. Polyglyoxylates (PGs) are a class of SIPs that can be synthesized in a one-pot reaction and designed to respond to different stimuli including light, heat, reduction, and oxidation. However, with the exception of poly(ethyl glyoxylate) (PEtG), the various glyoxylate monomers must be prepared and purified before polymerization, which can be difficult. Furthermore, PGs typically possess properties such as water-insolubility and low glass …

Polyglyoxylamides With A Ph-Mediated Solubility And Depolymerization Switch, Quinton E. A. Sirianni, Xiaoli Liang, Georgina K. Such, Elizabeth Gillies

Chemistry Publications

Self-immolative polymers (SIPs) are characterized by their ability to depolymerize in response to the cleavage of a single end-cap or backbone moiety, making them attractive for numerous applications including sensors, transient plastics, and delivery vehicles. For many applications, it would be desirable to have an SIP capable of depolymerizing selectively under mildly acidic aqueous conditions. However, the poor solubility of most SIPs in water, accompanied by the competing effects of end-cap cleavage and depolymerization mechanisms, has made this a challenge. Here, we describe the development of polyglyoxylamides (PGAms) with pendent amino groups to achieve solubility switching at mildly acidic pH, …

Using Covalent Modifications To Distinguish Protein Electrospray Mechanisms: Charged Residue Model (Crm) Vs. Chain Ejection Model (Cem), Lars Konermann, Douglas J. D. Pimlott

Chemistry Publications

Different mechanisms have been proposed for the formation of gaseous protein ions during electrospray ionization (ESI). In the charged residue model (CRM) ions are produced upon nanodroplet evaporation to dryness. This mechanism is thought to dominate in native ESI, where proteins retain compact conformations, with charge states close to the Rayleigh charge of protein-sized aqueous droplets. Much higher charge states are generated from proteins that are unfolded in solution. The chain ejection model (CEM) has been proposed for ESI under such denaturing conditions. In the CEM proteins are gradually expelled, while mobile H⁺ equilibrate between the droplet and its …

Structural Tuning And Spectroscopic Characterizations Of Polysulfide As Battery Materials, Daiqiang Liu

Electronic Thesis and Dissertation Repository

Polysulfide materials have drawn extensive attention for next-generation battery development since the current lithium-ion battery has almost reached its limit regarding energy density and safety issues. Many phosphorus and sodium sulfide materials have been used in different battery types, such as solid-state and sodium-sulfur batteries. However, there are still issues that prevent these techniques from applications. In recent years, there has been increasing attention on investigations of the structural and phase transformations of electrode and electrolyte materials under high pressure. Many studies have shown that external pressure can affect structural properties and influence electrical properties. In this study, three battery-related …

Hydrogen/Deuterium Exchange Measurements May Provide An Incomplete View Of Protein Dynamics: A Case Study On Cytochrome, Pablo M Scrosati, Victor Yin, Lars Konermann

Chemistry Publications

Many aspects of protein function rely on conformational fluctuations. Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) provides a window into these dynamics. Despite the widespread use of HDX-MS, it remains unclear whether this technique provides a truly comprehensive view of protein dynamics. HDX is mediated by H-bond-opening/closing events, implying that HDX methods provide an H-bond-centric view. This raises the question if there could be fluctuations that leave the H-bond network unaffected, thereby rendering them undetectable by HDX-MS. We explore this issue in experiments on cytochrome

Post-Polymerization ‘Click’ End-Capping Of Polyglyoxylate Self-Immolative Polymers, Peter G. Maschmeyer, Xiaoli Liang, Allison Hung, Oksana Ahmadzai, Annmaree L. Kenny, Yuan C. Luong, Timothy N. Forder, Haoxiang Zeng, Elizabeth R. Gillies, Derrick A. Roberts

Chemistry Publications

No abstract provided.

Self-Immolative Dendron Hydrogels, Karanpreet Gill, Xueli Mei, Elizabeth Gillies

Chemistry Publications

Smart hydrogels are of great interest in areas such as drug delivery and sensing. Dendrimer-based hydrogels can exhibit tunable properties due to their structural precision. We prepared hydrogels from self-immolative dendrons. Controlled hydrogel degradation in response to light was demonstrated and the hydrogel properties as a function of dendron generation were compared.

Characterization Of Extracellular Vesicles By Surface-Enhanced Raman Spectroscopy, Nina M. Culum

Electronic Thesis and Dissertation Repository

Extracellular vesicles (EVs), which are nanoscale vesicles secreted by cells into biofluids, are of research interest due to their roles in intercellular communication. EVs released from mesenchymal stromal cells (MSCs) have tremendous potential in cell-free regenerative medicine, while EVs released from diseased cells are being studied as biomarkers for minimally invasive and early disease detection. Presented in this thesis are gold nanohole arrays for the capture and sensitive detection of EVs by surface-enhanced Raman spectroscopy (SERS), a plasmonic technique capable of single molecule detection. Herein, we have characterized EVs released from MSCs and ovarian cancer cells, with a focus on …

Functional Nanoparticles: Tin Monoxide And Molybdenum Disulfide Quantum Dots On Graphene Nanosheets, Denys Vidish

Electronic Thesis and Dissertation Repository

Light harvesting can be referred to the use of an ensemble of different nanoparticles, or quantum dots, or other absorbers to optimize the ability to capture a given spectrum of electromagnetic radiation (for example the solar spectrum under specific atmospheric conditions) in a light-absorbing system. To this end, different nanoparticles play complementary functions within the system and absorb or scatter light at different wavelength intervals. Light harvesting finds applications in fields as diverse as solar cells, photosynthesis and photocatalysis. Graphene supporting a set of different semiconducting nanoparticles has often been proposed as light harvesters. To further this concept, my thesis …

Atomistic Insights Into The Formation Of Nonspecific Protein Complexes During Electrospray Ionization., Elnaz Aliyari, Lars Konermann

Chemistry Publications

Native electrospray ionization (ESI)-mass spectrometry (MS) is widely used for the detection and characterization of multi-protein complexes. A well-known problem with this approach is the possible occurrence of nonspecific protein clustering in the ESI plume. This effect can distort the results of binding affinity measurements, and it can even generate gas-phase complexes from proteins that are strictly monomeric in bulk solution. By combining experiments and molecular dynamics (MD) simulations, the current work for the first time provides detailed insights into the ESI clustering of proteins. Using ubiquitin as a model system, we demonstrate how the entrapment of more than one …

Pressure-Induced Polymorphic Transformations Of Ethylenediamine Bisborane, Rongfeng Guan, Pan Wang, Yang Song, Viktor N. Staroverov

Chemistry Publications

Pressure-induced phase transitions of crystalline ethylenediamine bisborane (EDAB), a prospective hydrogen storage material, are investigated using vibrational spectroscopy, X-ray diffraction, evolutionary crystal structure prediction, and density functional theory. The results indicate that EDAB undergoes two transitions in the 0–17 GPa pressure range: the first one is near 1 GPa, from the orthorhombic ambient-pressure Pbca structure (phase I) to a monoclinic structure of P21/c symmetry (phase II); the second is near 7 GPa, from phase II to another P21/c structure (phase III). The latter coexists with phase II and remains the most stable form of EDAB up …

Systematic And Collaborative Approach To Problem Solving Using X-Ray Photoelectron Spectroscopy, Neal Fairley, Vincent Fernandez, Mireille Richard-Plouet, Catherine Guillot-Deudon, John Walton, Emily Smith, Delphine Flahaut, Mark Greiner, Mark Biesinger, Sven Tougaard, David Morgan, Jonas Baltrusaitis

Chemistry Publications

The methodology presented within this work is a result of years of interactions between many junior and senior X-ray Photoelectron Spectroscopy (XPS) users operating within the CasaXPS spectral processing and interpretation program framework. In particular, discussions arising from a series of workshops have been a significant source for developing the overall XPS data processing concept and are the motivation for creating this work. These workshops organized by the Institut des Matériaux Jean Rouxel (IMN), Nantes gather both experienced and novice users of XPS for a week of discourse in conceptual experiment design and the resulting data processing. However, the framework …

Bioaccessibility And Reactivity Of Alloy Powders Used In Powder Bed Fusion Additive Manufacturing, Yolanda S. Hedberg

Chemistry Publications

Exposure to metal particles via the inhalation route unavoidably takes place at occupational settings during additive manufacturing of metals and alloys. This calls for investigations on possible adverse health effects. This study focuses on virgin and reused powders of three iron- and nickel-based alloy powders (316L, IN718, 18Ni300) widely used in additive manufacturing, and dust powder of 18Ni300 generated during laser melting. Investigations were performed from a physico-chemical and toxicological perspective assessing their bioaccessibility in artificial lysosomal fluid (ALF, simulating lung exposure to respirable particles), corrosion behavior, surface morphology and composition, microstructure, hydrodynamic size distribution in ALF, and in-vitro toxicity …

Synthesis And Characterization Of Re(I) Tricarbonyl Complexes Of 1,8-Naphthalimide, Priyanka Jagadeesa Prabhu

Electronic Thesis and Dissertation Repository

1,8-Naphthalimide fluorophores with amino-substituents absorb and emit in the visible region. The photophysical properties of this class of fluorophores can be modulated by altering the degree of Intramolecular Charge Transfer (ICT) in the excited state. Thus, several metal complexes with the 1,8-naphthalimide motif have been developed as cell imaging agents. In this project, four 1,8-naphthalimide ligands were synthesized by incorporating rigid linkers. Among these, three ligands also allowed the extension of π-conjugation to the naphthalimide moiety. In addition, a ligand was also synthesized without the use of a linker. Re(I) tricarbonyl complexes of these ligands were also synthesized and their …

Lithium Dubbed Cspbbr3 Perovskite Nanocrystals, Siena Idoine

Undergraduate Student Research Internships Conference

No abstract provided.

Structural Tuning Of Two-Dimensional Perovskites At High Pressure, Lauren A. Diloreto

Undergraduate Student Research Internships Conference

Two-Dimensional Perovskites are semiconductors and are of interest to researchers as the class of materials show great promise for innovating improvements to solar cells. The purpose of this experiment is to determine if a metastable change will occur in the materials: DPDAPbI4 and CMA2PbI4 upon compression to approximately 9 GPa. The experiment was conducted using diamond anvil cells (DAC) to apply static pressure to the materials. The pressure of the sample was then measured using ruby fluorescence. Then, FTIR or Raman spectroscopy acquisitions were obtained at various pressures. Subsequently, the data suggests that a metastable change did not occur. Additionally, …

A Photoswitchable Hydrogen Bond Array, Kristen L. Perry, Fereshteh Davoud, James A. Wisner

Undergraduate Student Research Internships Conference

No abstract provided.

Synthesis Of Photoluminescent Metal-Chalcogen Clusters For Potential Oled Applications, Aaron Mitchell

Undergraduate Student Research Internships Conference

No abstract provided.

Synthesis Of Nucleotide Prodrugs As Potential Antiviral Agents, Mohammed Attaelmanan

Undergraduate Student Research Internships Conference

No abstract provided.

Synchrotron X-Ray Characterizations Of Black Phosphorus: Preparation, Doping And Applications In Energy Storage, Minsi Li

Electronic Thesis and Dissertation Repository

Black phosphorus (BP), as a two-dimensional material, has attracted interest in recent decades due to its unique properties—tunable band gap and high carrier mobility. Specifically, BP shows ultra-high theoretical capacity of 2595 mA h g^-1, resulting in high potential practical applications in lithium-ion batteries (LIBs). However, several challenges limit the development of BP in the energy storage field and LIBs: 1) The cost of the current synthesis methods of BP is too high to support extensive research studies and practical applications; 2) The electrical conductivity of BP is insufficient in LIBs; 3) The huge volume change of BP …

The Design And Characterization Of Advanced Li Metal Anodes For Next-Generation Batteries, Keegan R. Adair

Electronic Thesis and Dissertation Repository

Li metal batteries have been widely regarded as the next stage of energy storage technology, which is enabled by the low electrochemical potential (-3.04 V vs. the standard hydrogen electrode) and high specific capacity (3860 mAh g^-1) of the Li metal anode. However, the implementation of Li metal anodes has been hindered by several issues including parasitic side reactions with electrolyte, large volume fluctuations, and dendrite formation which can cause short-circuits and safety issues. This thesis will cover some novel Li anode stabilization strategies while using advanced characterization techniques to provide critical information on the working mechanisms of …

Skin Permeation Of Nickel, Cobalt And Chromium Salts In Ex Vivo Human Skin, Visualized Using Mass Spectrometry Imaging, Lina Hagvall, Masoumeh Dowlatshahi Pour, Jiabao Feng, Moshtak Karma, Yolanda Hedberg, Per Malmberg

Chemistry Publications

Skin permeation and distribution of three of the most common skin sensitizers was investigated using a previ-ously developed animal-free exposure method combined with imaging mass spectrometry. Nickel, cobalt, and chromium (III) salts were dissolved in a buffer and exposed to human skin ex vivo, to be analyzed using time of flight secondary ion mass spectrometry (ToF-SIMS). Our findings demonstrate that metal haptens mainly accumulated in the stratum corneum, however all three metal sensitizers could also be detected in the epidermis. Cobalt and chromium (III) species penetrated into the epidermis to a larger extent than nickel species. The degree of penetration …