Chemistry Commons^™

Probing Biomolecular Structure And Dynamics Via Infrared Action Spectroscopy, Madeline Schultz

Open Access Dissertations

Biomolecular structure is supported by a network of inter- and intramolecular interactions, which can be inherently complex in the condensed phase. Isolating biomolecules from the condensed phase to vacuum, via electrospray ionization (ESI), can afford precise control over experimental conditions, yielding additional structural insight. However, the loss of solvation inherent to the ESI process can drive structural rearrangement, particularly at charge sites.

Microsolvation reagents can be used to partially mimic the solvation of charged moieties in solution as they are brought into the gas phase through complexation. This serves two primary functions: 1) reducing propensity for structural rearrangement of systems …

Characterization Of Methodological Variability In Compound Specific Isotope Analysis Of Amino Acids (Csia-Aa), Audreyana Brown-Nash

Open Access Dissertations

The use of isotopes in the natural sciences stems from the principle that chemical reactions predictably alter the isotopic composition of a given sample. Recent advances in compound specific isotope analysis of amino acids (CSIA-AA) have paved the way for studies of increasingly complex ecological relationships, including the identification and characterization of organismal physiology, consumer-resource linkages, biogeochemical cycling, and movement ecology. The analytical power of CSIA-AA has caused an exponential increase in the number of application-based studies since its inception in the 1990s. With the technique constantly evolving to accommodate new research goals, it is important to understand how variation …

Beyond The Phonon Gas Model (Pgm): Unraveling The Unique Mechanistic Processes Dictating Thermal Transport In Highly Anharmonic And Disordered Materials, Sandip Thakur

Open Access Dissertations

Thermal transport in nonmetallic solids has traditionally been described by the phonon gas model (PGM), in which heat is carried by weakly interacting phonon quasiparticles in an ordered crystalline lattice. However, this model breaks down in materials characterized by strong anharmonicity, dynamic disorder, or structural complexity, features prevalent in many next-generation materials used in energy conversion, optoelectronics, and thermal management. This dissertation investigates thermal transport in such complex materials, including metal halide perovskites (MHPs), covalent organic frameworks (COFs), metal organic frameworks (MOFs), and 2D-3D heterostructures, through large-scale molecular dynamics (MD) simulations and frequency-resolved spectral analyses.

In MHPs, the work reveals …

Perceptions, Efficacy, And Adaptation Of Online Learning In Physics And Chemistry Education, Fun Man Fung, Jia Yi Han, Min Xin Pua

Journal of Educational Technology Development and Exchange (JETDE)

The COVID-19 pandemic forced a sudden shift to online learning in Physics and Chemistry in Singapore. As restrictions eased, researchers explored its impact through interviews with instructors and analysis of student data made available through a data lake managed by the National University of Singapore’s Institute for Applied Learning Sciences and Educational Technology. Interviews focused on instructor adaptation and beliefs about online teaching, while the data investigated student perceptions and changes in teaching efficacy pre- and post-pandemic. Analysis of the students’ course feedback indicated that Course Code C005 received more positive feedback from students, particularly towards the instructor’s effectiveness in …

Open Path Spectroscopic Detection Of The Hydroxyl Radical: A Comparison Between Broadband Cavity-Enhanced Absorption Spectroscopy (Bbceas) And Bbceas Coupled With A Fabry-Pérot Interferometer (Bbceas-Fp), Callum Flowerday, Ryan Thalman, Matthew C. Asplund, Samuel A. Badstubner, Adam K. Cook, Philip Lundrigan, Jaron C. Hansen

ScholarsArchive Data

Data collected by the BBCEAS and BBCEAS-FP instruments described in the paper "Open Path Spectroscopic Detection of the Hydroxyl Radical: A Comparison Between Broadband Cavity-Enhanced Absorption Spectroscopy (BBCEAS) and BBCEAS coupled with a Fabry-Pérot Interferometer (BBCEAS-FP)"

Investigation Of Colorimetric Trends In Rare-Earth Co-Doped Ypo₄, Barit K. Essman

All Master's Theses

From detectors in scientific instrumentation to medical imaging devices and nuclear monitoring systems to LEDs seen in consumer products, phosphors are utilized in a myriad of applications experienced by both the general public and scientific community alike. For many phosphor applications, emission color and intensity are notably important features to consider. When phosphors are co-doped with rare-earth activators, the ability to predict emission intensity and color output becomes challenging due to competition kinetics and energy transfer between the dopants. During this study, correlation between trends in co-doped phosphor excitation and color output were analyzed to interpret optical behaviors originating from …

Phytochemistry Of Dalea Candida Var. Oligophylla, Ryan E. Galperin

All Master's Theses

The focus of this project was the plant Dalea candida and its phytochemistry. The plant compounds were isolated and purified by an array of chromatographic techniques. The structures of the pure compounds were determined by one-dimensional and two-dimensional ¹H and ¹³C NMR spectroscopy, supported by infrared and ultraviolet spectroscopy, experimental and calculated circular dichroism spectroscopy, and mass spectrometry. Plant parts were worked on separately since they typically differ in content. Purified compounds will be tested for biological activities. Based on our results, eight new or known compound were isolated, specifically four new compounds and four known compounds. Compound …

A Colorimetric Sensor Array For Differentiating Emerging Material Contaminants Based On Surface Chemistry, Ifunanya Chiamaka Ede

All Master's Theses

Emerging materials contaminants, such as microplastics (MPs) and engineered nanoparticles (ENPs), are now recognized to contaminate oceans, seas, freshwater, and drinking water through many different exposure pathways. The extent of the materials' water contamination problem has only begun to be properly appreciated in the last decade. While comprehensive global data on the exact quantity of nano- and microcontaminants in drinking water is challenging to ascertain, studies have shown that microplastics and nanoparticles can now be found in drinking water sources worldwide.  Indeed, a well-publicized recent study has shown that 93% of bottled water around the world contains microplastic contamination.

Detecting …

One Peak, Two Peaks: On The Effects Of Enhanced Evaporation In An Ammonium Sulfate And Succinic Acid Aerosol System, Julia Reynolds

Honors Theses

Aerosols, defined as suspensions of liquid or solid particles in a gaseous medium, are ubiquitous in both indoor and outdoor environments. They have significant impacts ranging from public health concerns to climate dynamics. In laboratory settings, aerosols are most often generated through a technique known as atomization. The atomization or nebulization is from dilute, aqueous solutions of various chemical compositions. This process typically produces a unimodal, lognormal particle size distribution with exceedingly rare exceptions. Colleagues in a different laboratory (Dr. Freedman’s Group at Pennsylvania State University), however, mentioned they observed a bimodal size distribution, a distribution with more than one …

Understanding The Prevalence Of Γ-Hydroxybutyric Acid In Hair For Clinical And Forensic Applications, Collin J. Kustera

Graduate Theses, Dissertations, and Problem Reports (ETD)

Sexual assault affects over 400,000 Americans annually, including 13% of college students, yet only 2.5% of assailants face incarceration. This disparity stems from significant challenges in evidence collection, particularly in drug-facilitated crimes (DFCs). Victims often delay reporting due to fear, self-blame, or unawareness of the assault which is common in cases involving substances like γ-hydroxybutyric acid (GHB). Current forensic standards rely on blood and urine, which offer detection windows of just 48 and 120 hours, respectively. These short timeframes frequently fail to capture critical toxicological evidence, leaving investigators with only victim testimony, which the judicial system struggles to act upon …

Refinement Of A Thermodynamic Model To Explain The Weathering Patterns Of Ignitable Liquids On Household Substrates At Elevated Temperatures, Chaney Ashlyn Ganninger

Graduate Theses, Dissertations, and Problem Reports (ETD)

ABSTRACT

Refinement of a thermodynamic model to explain the weathering patterns of ignitable liquids on household substrates at elevated temperatures

Chaney A. Ganninger

In 2021, arson caused more than 4,361 deaths in the United States. To aid in the differentiation between arson and accidental or natural causes, investigators often analyze fire debris for the presence of ignitable liquid residues using headspace concentration followed by gas chromatography-mass spectrometry (GC-MS). Classification of ignitable liquids can be confounded by weathering, which is the uneven evaporation of compounds in ignitable liquid residues. The Jackson group, among others, has developed a thermodynamic model to help …

Expanding The Vibrating Sharp-Edge Spray Ionization Toolkit For Oligonucleotide Characterization, Sultan Mahmud

Graduate Theses, Dissertations, and Problem Reports (ETD)

A gentle or soft Ionization process is a critical component in native mass spectrometry (MS) to lift the biomolecules from the bulk solution into the gas phase environment of the mass spectrometer preserving their shape, topology and non-covalent interactions. Electrospray ionization (ESI) facilitates structural preservation of proteins, nucleic acids and their complexes and as a result it has been extensively used in native MS. However, in negative ion mode, ESI is somewhat limited in sensitivity due to corona discharge effect resulting from the requirement of a high amount of voltage. This often disrupts the ESI process and may not preserve …

Forensic Characterization And Comparison Of Modern Nail Polish Products By Their Physical Features And Chemical Composition, Madison Meredith Lindung

Graduate Theses, Dissertations, and Problem Reports (ETD)

Nail polish can serve as valuable evidence in forensic investigations as it is often found on the hands and feet of individuals. Nail polish can break off and transfer easily during self-defense actions or forceful contact, such as in cases of kidnapping, sexual assault, or homicide. These residues can provide clues about who was at the scene, as well as where, when, and how the event evolved. However, compared to other types of paints commonly analyzed in forensic laboratories, limited forensic research has been conducted on the chemical composition and discrimination capabilities of popular nail products. The lack of information …

Introduction Of Polar Functional Groups To Pyridinedipyrrolide Zirconium Photosensitizers Through Post-Synthetic Modifications, Marisa Nicole Tordella

Graduate Theses, Dissertations, and Problem Reports (ETD)

Photosensitizers are vital components to applications such as photoredox catalysis, photodynamic therapy, and various avenues of solar energy production. The abilities of transition metal photosensitizers containing precious metals have been well studied over the years. However, because of the growing scarcity of these metals, there has been a shift in finding more earth abundant alternatives. To help fill this gap in the literature, the Milsmann group has developed and studied the photophysical properties of Zr(IV) complexes with various ligand systems. Due to the electron deficient metal center, these complexes exhibit ligand-to-metal charge transfer (LMCT), unlike the metal-to-ligand charge transfer commonly …

Effects Of Chain Length, Saturation, And Bases On Saponification, Sarah Fenik

Williams Honors College, Honors Research Projects

This project will analyze the effects of chain length and saturation of fatty acids on saponification processes, as well as the effects of the base used in the reaction. Stearic acid, lauric acid, and oleic acid will be used for the fatty acid comparisons, and sodium hydroxide and potassium hydroxide will be used for the base comparisons. Stearic acid is considered a long chain fatty acid, while lauric acid is considered a short chain fatty acid. Oleic acid is a monounsaturated fatty acid. Five soap products are be made: sodium stearate, sodium laurate, sodium oleate, potassium stearate, and potassium oleate. …

Cold Atmospheric Plasma Induced Degradation Of Organophosphate Pesticides On Kevlar Swatches, Ta Chun Lin, Victor Somtochukwu Mbanugo, Boluwatife Stephen Ojo, Yue-Wern Huang, Marek Locmelis, Frank Daoru Han

Biological Sciences Faculty Research & Creative Works

Cold atmospheric plasma (CAP) was evaluated for degrading organophosphate pesticide (OP) residues (acephate, malathion, and dimethoate) from Kevlar fabrics. Fourier transform-Infrared (FTIR) spectroscopy, scanning electron microscope (SEM) imaging and tensile strength testing confirmed that CAP treatment preserved Kevlar's structural integrity and mechanical properties. Results show degradation efficiency increased with higher power, shorter discharge gaps, and longer exposure duration. Hyperspectral imaging supported the detection of plasma-induced spectral changes, reinforcing the presence of reactive species. The strong oxidative potential of CAP facilitated the rapid breakdown of OPs into nontoxic byproducts. These findings demonstrate the potential of CAP as a portable, energy-efficient solution …

Metal-Free Photoredox Catalysis For The S-Trifluoromethylation Of Thiols, Raheemat Rafiu, Puspa Aryal, V. Prakash Reddy

Chemistry Faculty Research & Creative Works

The S-trifluoromethylation of thiols is accomplished using a simple and cost-effective organic catalyst (diacetyl) along with a bench-stable and environmentally friendly trifluoro methylating reagent (Langloi's reagent). Under optimized conditions (2.5 equivalents of Langlois reagent, Blue LED irradiation, 48-h reaction time at room temperature), the reaction yielded up to 81% S-trifluoro methylated product. This method's high yields, compatibility with a broad substrate scope (aliphatic, heteroaromatic, and aromatic thiols), and environmentally friendly conditions demonstrate its potential for broader synthetic applications. In contrast to traditional methods that rely on organometallic catalysts and environmentally hazardous reagents, this novel photoredox catalysis method offers a more …

Characterizing The Transient Emission Of Particles And Gases From A Single Puff Of Electronic Cigarette Smoke, Kashala Fabrice Kapiamba, Steven Achterberg, Ta Chun Lin, Philip D. Whitefield, Yue-Wern Huang, Yang Wang

Chemistry Faculty Research & Creative Works

This study employed high-time-resolution systems to examine the transient properties of aerosols and gases emitted from electronic cigarette (EC) puffs. Using a fast aerosol sizer, we measured particle size distributions (PSDs) across various EC brands (JUUL, VUSE, VOOPOO), revealing sizes ranging from 5 to 1000 nm at concentrations of 107 to 1010 cm-3. Most aerosols were found to be in the ultrafine range (below 100 nm), with JUUL-, VUSE-, and VOOPOO-producing aerosols with geometric mean sizes of 19.9, 47.3, and 29.4 nm, respectively. Applying the International Commission on Radiological Protection (ICRP) deposition model and assuming no further evolution of aerosols …

Formation Of Hydrocarbons And Carbon Oxides In Mxene Reactions With Water Under Varying Oxidative Conditions, Shuohan Huang, Guanglei Xiang, Vadym Mochalin

Chemistry Faculty Research & Creative Works

Titanium carbide / carbonitride MXenes have garnered significant attention due to their remarkable properties, versatile solution processability, and broad range of potential applications. However, when exposed to the environment, MXenes are susceptible to degradation, which ultimately leads to the formation of metal oxides, a process that may be regarded as either disadvantageous or beneficial, depending on the application of a MXene and our knowledge about the underlying mechanisms. Therefore, it is very important to understand the reactivity of MXenes in different environments and conditions. Although researchers have made efforts to understand MXene degradation in air and water, our knowledge of …

Instantaneous Hydrolysis Of Methyl Paraoxon Nerve Agent Simulant Is Catalyzed By Nontoxic Aminoguanidine Imines, Emmanuel Kingsley Darkwah, Puspa Aryal, Chi Zhang, Charles B. Musgrave, William A. Goddard, V. Prakash Reddy

Chemistry Faculty Research & Creative Works

Exposure to organophosphate-based nerve agents and pesticides poses health and security threats to civilians, soldiers, and first responders. Thus, there is a need to develop effective decontamination agents that are nonhazardous to human health. To address this, we demonstrate that instantaneous hydrolysis of methyl paraoxon (Me-POX), a nerve agent simulant, can be achieved in the presence of aminoguanidine imines at pH 10: ● the pyridine-4-aldehyde aminoguanidine-imine (1) and ● the 2,3-butanedione aminoguanidine-imine (2). The hydrolysis of Me-POX under these conditions is substantially faster than that of the state-of-the-art decontaminating agent, Dekon-139 (2,3-butanedione oxime, potassium salt). Furthermore, Dekon-139 shows adverse effects …

Synthesis And Characterization Of Free Radical Scavenging Dendrimer Nanogels Via Cross-Linking Reaction-Enabled Flash Nanoprecipitation, Lin Qi, Da Huang, Huari Kou, Anna Chernatynskaya, Nuran Ercal, Hu Yang

Chemistry Faculty Research & Creative Works

This work reports the development and evaluation of dendrimer-based nanogels based on Poly amidoamine (PAMAM) dendrimer generation 5, engineered to act as a carrier with reactive oxygen species (ROS)-scavenging capabilities. We developed a cross-linking reaction-enabled flash nanoprecipitation method in which the cross-linking reaction occurs during the flash nanoprecipitation process to form a cross-linked nanostructure. Using this approach, an N-hydroxy succinimide (NHS)-functionalized ROS-responsive thioketal cross-linker (TK-NHS) was synthesized and utilized to cross-link DAB-core PAMAM dendrimer G5, resulting in the formation of G5-TK nanogels. The resulting nanogels were characterized using dynamic light scattering and transmission electron microscopy, and their cytocompatibility, irritancy, cellular …

Pla-Based Bone Tissue Engineering Scaffolds Incorporating Hydroxyapatite And Bioactive Glass Using Digital Light Processing, Engin Gepek, Fateme Fayyazbakhsh, Lev Suliandziga, Vadym Mochalin, Osman Iyibilgin, Yue-Wern Huang, Ming C. Leu

Chemistry Faculty Research & Creative Works

Bone tissue engineering (BTE) aims to repair bone defects using biocompatible materials with tailored geometries and pore structures, providing appropriate mechanical support and control over biodegradation kinetics to promote bone growth. In this study, we utilized digital light processing (DLP) 3D printing to fabricate scaffolds with varying pore sizes using polymer–ceramic slurries composed of polylactic acid (PLA) as the main polymer matrix, incorporated with hydroxyapatite (HA) and bioactive borate glass (BBG) at various ratios. We studied the effect of composition on rheological behavior, printability, mechanical properties, bioactivity, degradation rate, and biocompatibility. While HA increased viscosity and reduced printing accuracy, it …

Unveiling Pseudocapacitance: A Kinetic Treatment Of The Pseudocapacitive Biosensor, Rokas Gerulskis, Egor Baiarashov, Maryam Karimi, Wassim El Housseini, Shelley D. Minteer

Chemistry Faculty Research & Creative Works

A kinetic framework is introduced for a pseudocapacitive potentiometric biosensor. Mathematical derivation and kinetic modeling demonstrate that experimentally observed linearity in analyte-OCP response arises from a dynamic equilibrium between competing redox reactions on a single electrode. This system can be expanded to develop a new generation of biosensors.

Mechanical And Thermal Characterization Of Additively Manufactured Carbon/Nylon 12 And Carbon/Peek Composites, Matik Heskin, Bradley Deuser, Thomas P. Schuman, K. Chandrashekhara, John Bayldon, Jeff Degrange, Steven Patterson, Neiko Levenhagen

Chemistry Faculty Research & Creative Works

This study explores additive manufacturing of carbon fiber-reinforced thermoplastic composites using the Composite-Based Additive Manufacturing (CBAM) process. Carbon/Nylon 12 and Carbon/PEEK composites were fabricated and evaluated through mechanical (compression, tensile, flexural, and impact) and thermal (DSC and TGA) tests. Carbon/PEEK exhibited superior mechanical performance, with 97.5% higher tensile strength, 79.8% higher elastic modulus, and 59.6% higher flexural strength compared to Carbon/Nylon 12. Thermal testing showed that Carbon/PEEK had higher thermal stability, beginning degradation at 350 °C versus 298 °C for Carbon/Nylon. These results indicate that CBAM-fabricated Carbon/PEEK composites are suitable for applications requiring high strength and temperature resistance.

Electrochemically Active Molybdenum Phosphate With Open-Framework Structure, Sutapa Bhattacharya, Milad Aghayi-Anaraki, Nikolay Gerasimchuk, Steven P. Kelley, Amitava Choudhury

Chemistry Faculty Research & Creative Works

Somewhat less investigated, lithium ion containing molybdenum phosphate compounds are synthesized via simple template free hydrothermal method. Single-crystal X-ray diffraction (SCXRD) study reveals that the compounds Li_0.89Mo₂O_1.89F_0.11(PO₄)2(H₂PO₄)·xH₂O (x ≈1) and Li₃Mo₂O₂(PO₄)₃·xH₂O (x ≈1) crystallize in monoclinic C2/m and C2/c space group, respectively. The structures are built of alternate corner-sharing of MoO₆ octahedra and PO₄ tetrahedra forming layers, which are pillared by phosphate groups creating a 3D framework with channels. These …

Atomistic Mechanisms Of Ti3alc2 Etching: Oxidation, Surface Stability, And Selectivity, Valentina Nesterova, Ana Maria Stratulat, Walter Malone, Vadym Mochalin, Majid Beidaghi, Konstantin Klyukin

Chemistry Faculty Research & Creative Works

Mechanisms governing MAX-phase etching set the properties and stability of resulting MXenes, yet the details of this complex process remain poorly understood. Combining thermodynamic analysis of surface chemistries with ab initio molecular dynamics and enhanced free-energy sampling, we directly model elementary steps at the MAX/etching solution interface. We find that purely thermodynamic analysis overestimates etching selectivity, which is governed by the kinetics of elementary reaction steps. Our calculations reveal that initial exposure to water drives localized, thermodynamically favored edge oxidation that seeds MXene-like terminations into the uppermost layers of Ti₃AlC₂ with oxygen occupying the interlayer space between …

Cloud Condensation Nuclei Activity Of Fresh And Aged Phenolic Acid Aerosol Particles, Emily A. Nortmann

Honors Undergraduate Theses

In recent years, the incidence of wildfires has considerably increased, with fire seasons starting earlier and ending later than usual due to changes in snowpack, precipitation, and temperature, which are attributed in part to climate change. Wildfires are responsible for the emission of a variety of gases and organic aerosol particles in the atmosphere with profound impacts on air quality, visibility, and human health. The aerosol particles produced by wildfires can contribute to climate change by scattering or absorbing solar radiation, affecting the radiative balance of the planet through cooling or warming effects, or by acting as cloud condensation nuclei …

Synthesis Of Novel Schiff Bases And Their Metal Complexes, Ryan J. Lukkarinen

Theses and Dissertations

Presented in this thesis is the synthesis and characterization of multiple thiosemicarbazones and dithiocarbazates, as well as their corresponding metal complexes. Chapter 1 is an introductory chapter exploring the significance and potential applications of this work. Chapter 2 focuses on thiosemicarbazone synthesis and characterization. Chapter 3 describes the synthesis and characterization of dithiocarbazates. Chapter 4 details metal complex synthesis using the previously described ligands. Chapter 5 summarizes the conclusions of the research and future work that may stem from it.

High Throughput, Solid Sample Analysis With Cone-Based Mass Spectrometric Ionization Sources, Emily J. Wiggins

Theses and Dissertations

The widespread presence of environmental and consumer-product contaminants (e.g. trace metals, opium alkaloids) has underscored the need for rapid, reliable, and high-throughput analytical techniques that are capable of handling complex solid samples. While traditional mass spectrometric (MS) methods tend to have high sensitivity and accuracy, they often require labor-intensive and time-consuming sample preparation steps that limit throughput and field applicability. This thesis investigates the use of 3D-Printed Cone Spray Ionization-Mass Spectrometry (3D-PCSI-MS) as an ambient ionization technique for the direct screening of contaminants from solid matrices, eliminating the need for traditional sample preparation and allowing for real-time analysis.

In …

Thermo-Rheological And Tribological Properties Of Low- And High-Oleic Vegetable Oils As Sustainable Bio-Based Lubricants, Abiodun Saka, Tobechukwu K. Abor, Anthony C. Okafor, Monday U. Okoronkwo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Vegetable oil-based lubricants have attracted increased research attention in recent decades as sustainable alternatives to conventional petroleum-based lubricants in metal machining. However, more studies are required to fully elucidate the thermo-rheological and tribological properties. This study presents an investigation of the thermo-rheological and tribological properties of different vegetable oils, including low- and high-oleic soybean oil, high-oleic sunflower, safflower, and canola oils. The lubricity, and evolution of viscosity and thermodynamic properties as a function of temperature were investigated to obtain important parameters including the viscosity index, flow behavior index, flow activation energy, specific heat capacity, thermal conductivity, coefficient of friction, contact …