Physical Sciences and Mathematics Commons^™

Combustion Soot Nanoparticles: Mechanism Of Restructuring And Mechanical Properties, Ali Hasani

Dissertations

Soot, a product of incomplete combustion of fossil fuels, is a global warming agent. The effect of soot particles on climate depends on their morphology. Freshly released soot particles are fractal lacey aggregates, but they often appear collapsed in atmospheric samples collected away from emission sources. A body of work has concluded that the collapse is caused by liquid shells when they form by vapor condensation around soot aggregates. However, some recent studies argue that soot remains fractal even when engulfed by the shells, collapsing only when the shells evaporate. To reconcile this disagreement, the effects of the condensation and …

Non-Traditional Methods For The Green Synthesis Of Fine Chemicals, Tara Renée Mooney

Graduate Masters Theses

Herein, the advancement of microwave-assisted flow synthesis is reviewed and the green nitration of arenes is investigated. First, microwave-assisted flow systems are described, followed by their synthetic and environmental applications. Microwave-assisted flow synthesis has been applied successfully in organic, inorganic, material, and biochemical syntheses as well as environmental applications such as water desalination and the removal of volatile organic compounds from the atmosphere. In the second part of the Thesis, the methodological development of the first catalyst and solvent-free nitration of m-xylene using only nitric acid is detailed. This environmentally friendly reaction proceeds without the use of harsh Brønsted acids, …

Metallacycle-Mediated Cross-Coupling As An Enabling Tool For Studies In Carbocycle Synthesis And Functionalization, Adam Barry Millham

Dartmouth College Ph.D Dissertations

Natural products, specifically complex, carbocyclic natural products, have served as the inspiration for novel methods development for decades. Over that time, metallacycle-mediated cross-coupling has arisen as a powerful means for the synthesis of fused carbocycles. This work details three methods for the synthesis and functionalization of carbocyclic motifs that have been enabled by Ti-mediated cross-coupling reactions. The first of these studies include a complementary method to the Pauson–Khand reaction for the synthesis of highly substituted cyclopentenones via Ti-mediated alkyne–β-ketoester coupling. The second project, a modern approach to steroidal tetracycles, will be discussed that features: (1) an alkoxide-directed metallacycle-mediated [2+2+2] annulation …

Speciated Isotope Dilution Mass Spectrometry In Combination With Thor’S Hammer Metaspike Technology For The Assessment Of Low-Level Biomarkers For Human Health Evaluation, Ashley Ebert

Electronic Theses and Dissertations

Our research team has been focused on quantifying important biological analytes in human blood samples to delineate the biochemical processes underlying certain states of dysfunction and evaluate treatment efficacy. These efforts have been guided by laboratory measurements with the input of medical experts. Speciated isotope dilution mass spectrometry (SIDMS) explained in detail in EPA Method 6800 has been successfully applied in the quantification of an important biomarker analyte for immune function and detoxification processes: glutathione. Past research has proven the molecule a biomarker for autism spectrum disorder (ASD) in the form of the reduced/oxidized glutathione (GSH/GSSG) ratio, and literature has …

Quantum Computations And Molecular Dynamics Simulations: From The Fundamentals Of Antimicrobial Resistance To Neurological Diseases, Angel Tamez

Electronic Theses and Dissertations

Biophysical phenomena are modeled using a combination of quantum and classical methods to interpret and supplement three distinct and diverse problems in this dissertation. In the first project, decarboxylation reactions are ubiquitous across chemical and biological disciplines, yet the origin of non-catalytic solvent effects remains elusive. Specific solvent structure and energetics have not been well described for the monoanion of malonate, nor corrected from the gas-phase charge-assisted intramolecular hydrogen bond model known as “pseudochair”. In the aqueous phase, a low-lying energy conformer known as the “orthogonal conformation” is computed to be preferred by a three-water cluster of hydrogen bonding over …

Gold (I) Tetrathiomolybdate Clusters: Synthesis, Characterization, Computational Studies, And Reactivity With Thiophenol And Selenophenol, Dhirgam Humaidy

Electronic Theses and Dissertations

This thesis describes the synthesis and reactivity of heterometallic complexes containing medicinally active Au(I) and tetrathiomolybdate, [MoS₄]^2-. The research is motivated by the idea of multifunctional drugs, which are designed to treat diseases through two or more mechanisms of action. Five clusters of the general form, [MoS₄(AuL)₂] were prepared: C-1 (L=IPr), C-2 (L=IBzMe), C-3 (L=IMes), C-4 (L=PPh₃), and C-5 (L=PEt₃). The clusters with NHC ligands, C-1, C-2, and C-3 were prepared for the first time and thoroughly characterized by ¹H NMR,¹³C{¹H} …

Acetylacetone Oxidation At Room Temperature: A Multiplexed Photoionization Mass Spectrometric Investigation, Study Of The Russell Intermediates In Gas Phase Reactions, And The Investigation Of Oxidation Reaction Products Of Ethanol At Room Temperature, Sara Gallarati

Master's Theses

This thesis presents the combustion study of acetyl acetone using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at 298 K. The experiments were performed at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source of the Lawrence Berkeley National Laboratory. The reaction of acetyl acetone with chlorine (Cl) radicals was analyzed based on their photoionization spectra and reaction kinetic profiles.

Additionally, a study of the Russell intermediate has been performed. Previous to experimentation at the Advanced Light Source, computational analysis has been investigated to evaluate compounds that could possibly lead to the formation of a stable species. The …

Sunflower Oil-Based Polyol In Flame-Retardant Rigid Polyurethane Foams, Magdalene Asare

Electronic Theses & Dissertations

The current shift from solely depending on petroleum sources to seeking renewable alternatives is due to their fast depletion, spike in prices, and the need to reduce our carbon footprint. For instance, the polyurethane industry currently calls for renewable and less toxic polyols and isocyanates for their synthesis over the traditionally used ones. To tackle an aspect of this matter, this work investigates the generation of polyol from sunflower oil, and further probes their use in rigid foams, one of the widely utilized polyurethanes. Epoxidation and ring-opening reactions were used to convert the sunflower oil into a more reactive form, …

Bio-Based Uv-Curable Films And The Effect Of Bio-Content On The Properties Of The Films, Sahilkumar Chaudhary

Electronic Theses & Dissertations

The use of renewable resources in film formation has become a new focal point for industry because it is abundantly available and has less carbon emission during production than traditional ones. This has drawn researchers to investigate the functionality of bio-based raw materials and their end-usage. By modifying their chemical structures, the properties of these films like thermal resistance, impact resistance, and chemical resistance can be increased. In this research, limonene was used as a partial replacement for petroleum-based chemicals in film formation. A two-step chemical process was carried out to modify the limonene and the final product was used …

Development Of Novel Nucleophile-Intercepted Beckmann Fragmentations And Progress Toward The Total Synthesis Of 2(S)-Cathafoline, Evan M. Dunkley

Dartmouth College Master’s Theses

This thesis is comprised of two chapters, the first being the discovery of a novel nucleophile-intercepted Beckmann fragmentation of [2.2.1] indoline systems that resulted in highly stereo- and regioselective reactions. Chapter one details the exploration of this reaction as well as its relevant background information detailing its significance. Chapter two describes the application of the novel nucleophile-intercepted Beckmann fragmentation in the context of a total synthesis of akuammilline alkaloid 2(S)-cathafoline. While the target natural product was never synthesized, unpredicted reactivity resulted in interesting discoveries worthy of discussion.

Local Spectroscopy Data Infrastructure: Solid State Nmr Crystallography With Experiment, First-Principal Analysis And Machine Learning, He Sun

Arts & Sciences Electronic Theses and Dissertations

Solid-state magnetic resonance (SSNMR) spectroscopy is a powerful tool for obtaining precise information about the local bonding and morphology of materials. The detailed local structure of crystalline materials cannot be easily solved by traditional experimental methods such as X-ray diffraction (XRD). SSNMR combined with first principal calculation methods such as density functional theory (DFT) can be of great use in this research area. The methodology that is called “NMR crystallography” today has been widely applied to the determination of a wide range of solid materials with an increasing amount of computationally simulated NMR spectra. The construction of a well-established computational …

Development Of Redox-Responsive Phenazine-Based Foldamers. Acylative Kinetic Resolution Of Hydroxamic Acids, Jingwei Yin

Arts & Sciences Electronic Theses and Dissertations

Two different research directions have been presented in this thesis. The first project is about phenazine-based foldamers as molecular actuators. Researchers have been interested in the design and synthesis of foldamers and molecular actuators for years. We began our exploration by demonstrating that phenazine-1,6-dicarboxamides can function as redox-responsive molecular switches. We then designed and synthesized two generations of phenazine-based interleafed foldamers and studied their stability and redox behaviors under chemical and electrochemical conditions. In the second project, we have developed the first acylative kinetic resolution on hydroxamic acids. Although chiral hydroxamic acids have extensive applications, synthetic methods towards them are …

The Effect Of Ionization Density In Applications Of Radiation Detection, Dosimetry, And Therapy, Daniel Mulrow

Arts & Sciences Electronic Theses and Dissertations

This dissertation covers a wide range of topics but is linked by the common theme of radiation interacting with materials and studying the result of those interactions. The introduction describes the fundamentals of how radiation interacts with material and how we are able to detect that radiation and the application of how we use those interactions in radiation oncology. The thesis starts with a chapter detailing the temperature dependence of the photophysics in two organic scintillators. This chapter is the foundation for a future study that will look the degree to which these scintillators can distinguish between gammas and neutrons …

Toward Enhancing The Synthesis Of Renewable Polymers: Feedstock Conversions And Functionalizable Copolymers, Tedd Casey Wiessner

Arts & Sciences Electronic Theses and Dissertations

This thesis describes research under the rubric of the Center for Sustainable Polymers that is aimed at two separate goals. The goal of the first project (Chapters 1 and 2) was to develop a deeper mechanistic understanding of a method for the synthesis of linear α-olefins, while the second aimed at synthesizing statistical copolymers that incorporate olefin-containing monomers through ring-opening transesterification polymerization and showing that these copolymers could be functionalized. In Chapter 1, published methods for the conversion of fatty acids to linear α-olefins are reviewed to provide context for the mechanistic work we accomplished (Chapter 2). In Chapter 2 …

Effects Of Surface Ligation On Charge Extraction From Wurtzite Cadmium Selenide Quantum Platelets And Quantum Belts, Hailey Meyer

Arts & Sciences Electronic Theses and Dissertations

This dissertation presents the synthesis of flat, colloidal wurtzite CdSe quantum platelets and quantum belts for ligand exchange to novel and existing organic and inorganic L-, X-, and Z- type ligands. Use of these ligands in conjunction with the semiconductor nanocrystals allows for examination of their ligand exchange abilities, photoluminescence quenching efficiencies, and charge transfer properties.

First, zinc and cadmium dithiocarbamate compounds [M(S2CNR1R2)2] are used as ligands on wurtzite CdSe quantum belts. Complete ligand exchange is achieved when the belts are initially ligated with Cd(oleate)2, a Z-type ligand, prior to the exchange, as opposed to n-octylamine or ammonia, which are …

Functionalized Plasmonic Nanostructures For Ultrasensitive Single Cell Analysis, Priya Rathi

Arts & Sciences Electronic Theses and Dissertations

Ultrasensitive detection and quantification of soluble, secreted and cell surface-bound proteins is critical for advancing our understanding of cellular systems, enabling effective drug development, novel therapies, and bio-diagnostics. However, exiting technologies are largely limited by their sensitivity, making the detection and quantification of low-abundant proteins extremely challenging. This forms a major barrier in various fields of biology and biomedical sciences. In this work, we introduce novel cellular analysis methodologies based on plasmon-enhanced fluorescence for analyzing cell structure and probing surface and secreted proteins from cells. In the first part, we introduce plasmon-enhanced expansion microscopy and demonstrate the effectiveness of employing …

An Imaging Mass Spectrometry Investigation Into The N-Linked Glycosylation Landscape Of Pancreatic Ductal Adenocarcinoma And The Development Of Associated Tools For Enhanced Glycan Separation And Characterization, Colin Mcdowell

MUSC Theses and Dissertations

The severity of pancreatic ductal adenocarcinoma (PDAC) is largely attributed to a failure to detect the disease before metastatic spread has occurred. CA19-9, a carbohydrate biomarker, is used clinically to surveille disease progression, but due to specificity challenges is not suitable for early discovery. As CA19-9 and other prospective markers are glycan epitopes, there is great clinical interest in understanding the glycobiology of pancreatic cancer. Unfortunately, few studies have been able to link glycosylation changes directly to pancreatic tumors and instead have focused on peripheral glycan alterations in the serum of PDAC patients. To address this gap in our understanding, …

The Chemistry And Catalytic Activity Of Dehydrogenative Silylation And Hydroboration Of Complexes Bearing Semirigid Ligands With Group 14 Elements, Niroshani S. Abeynayake

Theses and Dissertations

Incorporation of silicon in the ligand backbone would yield electron-rich metal complexes upon coordination to transition metal complexes. The coordination chemistry of semirigid benzyl phosphines bearing a single or multiple phosphorus atoms and varying number of Si−H moieties has gained interest in recent years. This dissertation focuses on synthesizing silyl and germyl transition metal complexes of groups 9 and 10. Chapter II presents the synthesis of a family of four coordinated 14-electron rhodium complexes. The newly synthesized complexes were characterized in solution by multinuclear NMR spectroscopy and in the solid-state by single-crystal X-ray diffraction. These d⁶ complexes possess sawhorse …

Molecular Insights Into The Redox Of Atmospheric Mercury Through Laser Spectroscopy, Rongrong Wu Cohen

Theses and Dissertations

The widespread pollution of mercury motivates research into its atmospheric chemistry and transport. Gaseous elemental mercury (Hg(0)) dominates mercury emission to the atmosphere, but the rate of its oxidation to mercury compound (Hg(II)) plays a significant role in controlling where and when mercury deposits to ecosystems. Atomic bromine is regarded as the main oxidant for Hg(0) oxidation, known to initiate the oxidation via a two-step process in the atmosphere – formation of BrHg (R1) and subsequent reactions of BrHg with abundant free radicals Y, i.e., NO2, HOO, etc. (R2), where the reaction of BrHg +Y could also lead to the …

The Design, Synthesis, And Investigation Into Small Molecule Modulators Of The Src Homology 2 Domain-Containing Inositol 5’-Phosphatase (Ship), Shea Thomas Meyer

Dissertations - ALL

The PI3K pathway is a major cell signaling pathway that influences survival and longevity in eukaryotic cells. Abnormal signaling of this pathway has been implicated in a number of disorders, including Alzheimer's disease and cancer. The PI3K pathway utilizes the inositolphospholipid PI(3,4,5)P3 as a key secondary messenger in the transmission of signals from outside the cell to the nucleus. The SRC Homology 2 containing Inositol 5’-Phosphatase (SHIP) also plays a key role in the PI3K pathway, mediating hydrolysis of the inositol phospholipid PI(3,4,5)P3 to PI(3,4)P2. Early testing has shown modulation of SHIP activity through the use of small molecule modulators …

Standardization Of A Latent Blood Visualizer Based Upon Dna Degradation, Kailey M. Van 'T Hoff

Honors Projects

Latent blood visualizers have been used in forensic science since 1937 beginning with Luminol. These visualizers through different types of reactions react with trace amounts of blood that cannot be seen with the naked human eye. These different reactions produce color that can then be seen by examiners. The four types of latent blood visualizers that were compared is luminol, leuco crystal violet, fluorescein, and bluestar. Luminol and bluestar use chemiluminescence, fluorescein uses florescent, and leuco crystal violet uses oxidation to react with iron in hemoglobin. At crime scenes when blood is detected which includes with the blood visualizers the …

Computer Simulation Of The Light Absorption Band Of The Jumping Spider Isorhodopsin, Noah Zoldak

Honors Projects

In order to simulate the photoisomerization of the 9-cis Jumping Spider Isorhodopsin (JSiR-1) it is necessary to first simulate its light-absorption band. Here we report on the absorption band simulated using protein models constructed using the advanced Automatic Rhodopsin Modeling (a-ARM) program. A population of S₀ models was created and the corresponding S₀ to S₁ transitions were determined for each member of the resulting population. The calculation resulted in a Gaussian plot showing that the wavelength of the absorption maximum of 560 nm (a violet color) that is consistent, but red-shifted, with respect the experimentally observed value.

Efforts Towards The Asymmetric De Novo Synthesis Of Lanostanes And Euphanes, Htoo Tint Wai

Dartmouth College Ph.D Dissertations

Tetracyclic triterpenoids are ubiquitous in nature and biology, with members displaying a wide range of medically relevant properties and occupying rather distinct regions of chemical space. Members of this large class include well-known steroid hormones and sterols as well as structurally interesting subclasses such as lanostanes and euphanes, among others. Comprised of the tetracyclic skeleton with three stereodefined quaternary centers at ring-junction positions, lanostanes and euphanes present synthetic challenges that are different from those encountered in efforts targeting the structurally less complex steroid hormones. Lanostanes, in particular, stand as a historically important class of compounds as significant attention has been …

Synthesis And Surface Modification Of Azide Decorated Silver Nanoclusters, Alexander H. Stöckli

Electronic Thesis and Dissertation Repository

In nanocluster research, easy modification of the cluster surface while maintaining the cluster core remains a key challenge. Herein we report the synthesis, structure, and properties of four targeted Ag₂₀ nanoclusters (NCs) with surface azide moieties, two of which have 8 azide moieties, [CO₃@Ag₂₀(S^tBu)₁₀(m-N₃-C₆H₄COO)₈(DMF)₄] and [CO₃@Ag₂₀(S^tBu)₁₀(p-N₃-C₆H₄COO)₈(DMF)₄], and two of which have 6 azide moieties, [CO₃@Ag₂₀(S …

Elucidating The Importance Of Structure, Surfaces, And Interfaces In Polymer Nanoparticles And Nanocomposites, Jacob E. Fischer

Doctoral Dissertations

This dissertation details research conducted to elucidate the importance of structure, surfaces, and interfaces in both polymeric nanoparticles and polymer nanocomposites. The fundamental understanding that is garnered in these studies provides a foundation to rationally develop nanocomposites tailored for unique functionalities, performance and applications.

Soft polymeric nanoparticles, have shown to imbue non-traditional diffusive properties, the strength of which decreases with crosslinking density of the nanoparticle. The crosslinking dependent morphology of these nanoparticles is first characterized in a dilute solution of good solvent (Chapter 2). The scattering results revealed that the structure ranges from a swollen polymer in good solvent (0% …

Controlling Polymer Molecular Structure And Morphology: From Illumination Of Conjugated Polymers To Polymer Chain Depolymerization, Josh Moncada

Doctoral Dissertations

Polymers remain a prominent component of our lives, and finding methods to control their structure or morphology are needed to tune material properties. This dissertation reports methods to alter the conformation, morphology, or structure of polymeric materials. Chapter two describes the impact of exposure to white light during annealing of conjugated polymer blends on their morphology and optoelectronic performance. The observed changes in the morphology correlate strongly to the variation in photoluminescence (PL) with illumination, including that the PL varies less with illumination at higher Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] loadings, offering foundational understanding to guide the structure and optoelectronic performance of conjugated polymer …

Intra-Skeletal Variation In Stable Isotopes Through Non-Destructive Approaches: Applications Of The Patterns Of Skeletal Remodeling To Biological Anthropology, Armando Anzellini

Doctoral Dissertations

Stable isotope analysis is a well-established method in biological anthropology used to deliver data on residence, diet, and life history. Samples for these analyses are often collected from the diaphyses of long bones with an assumption of an expected rate of turnover between five and ten years, depending on the skeletal element. However, the biological foundations of this assumption are still uncertain, especially concerning the intra-skeletal and intra-element variation of isotopic signatures that may relate to patterns of remodeling. Exploring these gaps in intra-element isotopic variation requires fine-grained work using multiple bones from multiple individuals, but such work is limited …

Light Matter Interactions: A Study Of Soft Materials Using Linear And Nonlinear Spectroscopy, Muhammad Redwan Hassan

Doctoral Dissertations

The adoption of complex fluids for various industrial applications is becoming normal. Complex fluids offer tunability, wide range solubility, and chemical and thermal stability which are the factors that conventional polar and non-polar solvents often lack. However, fundamental studies of these fluid systems are still lacking which is limiting the appropriate use of these complex fluids in many applications. The goal of this dissertation was to study and characterize complex fluids for application in electrolytes for redox flow batteries. Chapter 3 and chapter 4 feature the study of microemulsions and deep eutectic solvents (DES) by fluorescence techniques. Fluorescence studies of …

Analytical Techniques For The Analysis Of Uranium Bearing Materials, Nathaniel D. Fletcher

Doctoral Dissertations

The interest in the use of nuclear power has increased drastically in recent years. This is due to significantly increased efficiency at producing energy when compared to fossil fuels. With the increased use of nuclear power comes an increased need to for monitor for uranium bearing materials outside of regulatory control. This dissertation covers four projects aimed at improving the analysis of these materials. The first projects aims to develop a method that allows for the analysis of elements that exist in nature as anions by triple quadrupole ICP – MS. This would allow for the ability to measure more …

Transition Metal Computational Catalysis: Mechanistic Approaches And Development Of Novel Performance Metrics, Brett Anthony Smith

Doctoral Dissertations

Computational catalysis is an ever-growing field, thanks in part to the incredible progression of computational power and the efficiency offered by our current methodologies. Additionally, the accuracy of computation and the emergence of new methods that can decompose energetics and sterics into quantitative descriptors has allowed for researchers to begin to identify important structure-function relationships that predict the properties of unexplored subspaces within the overall chemical space. Catalytic descriptors have been used frequently in data driven high-throughput computational screenings. With the use of machine learning, a large portion of the chemical space an be predicted in matter of minutes or …