Physical Chemistry Commons^™

Characterization Of L-Band Resonators And Relaxation Times Of Soₓ- Radicals At X-Band, Georgina Naa Odey Amassah

Electronic Theses and Dissertations

Electron Paramagnetic Resonance (EPR) analysis requires resonators optimized for specific experimental challenges. Volume resonators enclose samples, while surface coil resonators allow imaging of larger subjects. For in vivo studies, L-band frequencies are commonly used because they offer a good balance between signal-to-noise ratio (S/N) and the ability to penetrate tissue. Rapid Scan (RS) EPR at L-band frequencies was chosen for my studies of resonators because of this balance but presents a challenge for sensitivity.

The spatial position dependence of signal intensity was evaluated for selected paramagnetic samples using 10 mm and 30 mm surface coils. The 10 mm coil, with …

Effect Of Bond Strength Variation And Ionizing Radiation On Mutations In Cytosine-Guanine Islands, Joshua Robert Bedwell, Yan Poniatovskyi, Vola Andrianarijaona

Achieve

Ionizing radiation produces free electrons within cells which then ionizes DNA and has the potential to cause carcinogenic mutations. Cytosine-Guanine (CpG) islands are regions that are rich in cytosine and guanine bases and are common sites of single point mutations and strand breaks. In this study, density function theory (DFT) is used to calculate the potential energy of DNA nucleotide dimers varying bond lengths in five different ionized states. Crossing between two ionized states can be seen in the potential energy curves, indicating the possibility of natural transition between the two states. Potential energy curves are used to determine bond …

Analyzing The Strength Of The Amine Bond Of Guanine Via Potential Curve Analysis: A Computational Approach, Yan Poniatovskyi, Joshua Robert Bedwell, Vola Andrianarijaona

Achieve

The deamination of guanine can be a cause of single point DNA mutations. In this study, the strength of the amine bond was examined using DFT and B3LYP to map out the bond’s potential curves under conditions of various charges being imposed on the molecule. Such an approach yielded a few potential curves that do not exhibit the expected behavior and rather, show crossings in potential energy curves. Discussions regarding the suspected causes of these unexpected behaviors are included in the poster presentation. The Mulliken charge analysis of guanine under these conditions is coherent with the proposition that the deamination …

Efficient Decontamination Of Organophosphate-Based Pesticides And Nerve Agent Simulants Mediated By N-Containing Nucleophiles, Emmanuel Kingsley Darkwah, Puspa Aryal, Saidulu Todeti, Jared Kenik, Samuel Insall, V. Prakash Reddy, Chariklia Sotiriou-Leventis

Chemistry Faculty Research & Creative Works

There is a growing interest in developing safer and more effective decontaminating agents for organophosphate-based pesticides and nerve agents. In this study, we present an effective method for the nonaqueous decontamination of these compounds using small-molecule-based decontaminating agents under ambient conditions. Our approach utilizes aryl and heteroaryl carboxaldehyde hydrazones and hydrazides to effectively hydrolyze nerve agent simulants into their nontoxic degradation products. The effectiveness of this method was evaluated using a range of nerve agent simulants, including dimethyl 4-nitrophenyl phosphate (DMNP), dimethyl methyl phosphonate (DMMP), and triphenyl phosphate (TPhP). In the presence of the heteroaryl hydrazone, the rate of hydrolysis …

Dynamic Mutational Profiling Of Binding Interactions And Allosteric Networks In Conformational Ensembles Of The Sars-Cov-2 Spike Protein Complexes With Classes Of Antibodies Targeting Cryptic Binding Sites: Confluence Of Binding And Allostery Determines Molecular Mechanisms And Hotspots Of Immune Escape, Mohammed Alshahrani, Vedant Parikh, Brandon Foley, Gennady M. Verkhivker

Mathematics, Physics, and Computer Science Faculty Articles and Research

The ongoing evolution of SARS-CoV-2 variants has underscored the need to understand not only the structural basis of antibody recognition but also the dynamic and allosteric mechanisms that could underlie complexity of broad and escape-resistant neutralization. In this study, we employed a multi-scale approach integrating structural analysis, hierarchical molecular simulations, mutational scanning and network-based allosteric modeling to dissect how Class 4 antibodies (represented by S2X35, 25F9, and SA55) and Class 5 antibodies (represented by S2H97, WRAIR-2063 and WRAIR-2134) can modulate conformational behavior, binding energetics, allosteric interactions and immune escape patterns of the SARS-CoV-2 spike protein. Using hierarchical simulations of the …

Assembly Of Non-Close-Packed Poly(N-Isopropylacrylamide) Microgels On Metal Halide Perovskite Films, Amal Alruwaili, Osama M. Alkhudhari, Ran Wang, Zhenyu Jia, Jennifer M. Saunders, Eugenio Picheo, Daniel T.W. Toolan, L. Andrew Lyon, Brian R. Saunders

Engineering Faculty Articles and Research

Hypothesis

Experiments

Computational Investigation Of Energetic Materials: Influence Of Electronic And Steric Properties On Sensitivity And Decomposition Mechanisms, Elizabeth Ruth Zengel

Chemistry & Biochemistry Theses & Dissertations

Developing novel high energy density materials (HEDMs) requires knowledge of the causes and mechanisms of detonation. These chemical events are almost instantaneous and involve the release of a large amount of energy, which limits the experimental studies that can be performed on them. Computational methods including density functional theory (DFT) and molecular dynamics (MD) simulations have been used to investigate trigger bonds, those which break to initiate detonation. These bonds are commonly found within explosophores, substituents that increase the explosive potential of a molecule.

The Wiberg bond index (WBI) is an estimation of orbital overlap and bond strength between two …

Numerical Simulation Of The Pitting Corrosion Behavior Of Stainless Steel Bellows Influenced By Varying Liquid Film Thicknesses, Lu-Jun Ren, Guo-Min Li, Zhen-Xiao Zhu, Hai-Yan Xiong, Bing Li

Journal of Electrochemistry

To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions, this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses. The model incorporates localized electrochemical reactions, oxygen concentration, and homogeneous solution reactions. For improved computational accuracy, the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions. Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions. With …

Research Progress On Thermal Management Of Lithium-Ion Batteries, Hong-Da Li, Qiu-Wan Shen, Zhao-Yang Zhang, Xin-Yue Zhao, Yuan Wei, Shi-An Li

Journal of Electrochemistry

Nowadays, new energy technologies are developing rapidly, energy storage systems are widely used, and lithium-ion batteries occupy a dominant position among them. Therefore, it is also very important to ensure their performance, safety and service life through thermal management technology. In this paper, the causes of thermal runaway of lithium batteries are reviewed firstly, and three commonly used thermal management technologies, namely, air cooling, liquid cooling and phase change material cooling, are compared according to relevant literature in recent years. Air cooling technology has been widely studied because of its simple structure and low cost, but its temperature control effect …

Regulating The Amount Of Graphene Oxide For Enhanced Capacitive Energy Storage Of Mof Derived Materials, Yong-Ji Qin, Jing-Quan Yang, Hao Wang, Mei-Ling Lian, Pei-Pei Jia, Jun Luo, Xi-Jun Liu, Jun-Feng Liu

Journal of Electrochemistry

In pursuit of more efficient and stable electrochemical energy storage materials, composite materials consisting of metal oxides and graphene oxide have garnered significant attention due to their unique structures and exceptional properties. Graphene oxide (GO), a two-dimensional material with an extremely high specific surface area and excellent conductivity, offers new possibilities for enhancing the electrochemical performance of metal oxides. In this work, we synthesized metal- organic framework (MOF) and GO composites by regulating the amount of GO, and successfully prepared composites of metal oxides supported by nitrogen-doped carbon frameworks and GO through a simple one-step calcination process. Based on the …

Ionic Liquid Enhanced Proton Transfer For Neutral Oxygen Evolution Reaction, Ming-Xing Chen, Nian Liu, Zi-He Dua, Jing Qi, Rui Cao

Journal of Electrochemistry

The development of highly active catalyst in pH-neutral media for oxygen evolution reaction (OER) is critical in the field of renewable energy storage and conversion. Nevertheless, the slow kinetics of proton-coupled electron transfer (PCET) hinders the overall OER efficiency. Herein, we report an ionic liquid (IL) modified CoSn(OH)₆ nanocubes (denoted as CoSn(OH)₆-IL), which could be prepared through a facile strategy. The modified IL would not change the structural characteristics of CoSn(OH)₆, but could effectively regulate the local proton activity near the active sites. The CoSn(OH)₆-IL exhibited higher intrinsic OER performances than the pristine …

A Study Of Machine Learning Techniques In Solving Biochemical And Chemical Problems, Kenneth Micheal Plackowski

Chemistry and Chemical Biology ETDs

Data-driven approaches to solving problems in biology and chemistry require utilization of reliable techniques and machine learning algorithms are the modern reliable approach. This work presents three problems that involve use of supervised learning techniques when classification is the goal and unsupervised learning techniques when global data representation is the goal.

In the first problem, we demonstrate the use of unsupervised clustering techniques, self-organizing maps and K-means, to ascertain analyte detection capabilities of carbon nitride dots. In the second problem, we add scalability features to a functional group classification model applied to infrared data and evaluate its ability to inform …

Nanoporous Gold Nanoparticles And Model Membrane Systems Applied To The Study Of Lipopolysaccharide (Lps), Dhanbir Lingden

Dissertations

Lipopolysaccharide (LPS), a key structural component of Gram-negative bacteria, is a major trigger of sepsis and septic shock, the systemic inflammatory conditions responsible for millions of deaths annually. Even at concentrations as low as 1 ng/mL, LPS can activate the immune system and initiate inflammatory cascades. According to the Global Burden of Disease Study 2017, sepsis accounted for 48.9 million cases globally, with 11 million deaths, emphasizing the urgent need for improved diagnostic and therapeutic strategies.

Accurate and rapid detection of LPS is vital for early intervention and improved clinical outcomes. While traditional detection methods are still widely used, modern …

Modified 2-Quinolinones For Photocatalysis: The Fluorescence Quantum Yield (Φf) Of Novel 2-Quinolinone Derivatives, Reggina Moreno Trevino, Graham Griffin

DePaul Discoveries

The photophysical properties of novel 2-quinolinone derivatives were examined to evaluate their potential as photocatalysts using fluorescence and UV-Vis absorbance spectroscopy. The fluorescence quantum yields were determined via the relative comparative method, using target absorbance values at a specific wavelength to prepare solutions and comparing these measurements to the reference molecule carbostyril-124. Molar absorptivity values were also calculated to assess the light absorption properties for each compound. Among the derivatives, PAV-3 presented with the highest molar absorptivity and fluorescence quantum yield values (ε= 15297.3 M-1 cm-1, ΦF= 17.1%), while PAV-5 showed the lowest (ε= 4796.2 M-1 cm-1, ΦF= 2.3%). The …

Vacuum Consistent Electrochemistry In Ionic Liquid Combined With Oxide Epitaxy, Yuji Matsumoto

Journal of Electrochemistry

We introduce our state-of-the art of “vacuum consistent electrochemistry” to an investigation of the interfaces between oxides and ionic liquid (IL). Pulsed laser deposition (PLD) has been one of the powerful and sophisticated techniques to realize nanoscale preparation of high-quality epitaxial oxide thin films. On the other hand, electrochemistry is a simple, very sensitive, and non-destructive analysis technique for solid-liquid interfaces. To ensure the reproducibility in experiment of the interfaces of such epitaxial oxide films, as well as bulk oxide single-crystals, with IL, we employ a home-built PLD-electrochemical (EC) system with IL as an electrolyte. The system allows one to …

Pm Irras Studies Of Organized Molecular Films At A Gold Electrode Surface, Zhang-Fei Su, Ai-Cheng Chen, Jacek Lipkowski

Journal of Electrochemistry

This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) to provide molecular-level information about the structure, orientation and conformation of constituents of thin films at electrode surfaces. PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced, while the s-polarized beam is attenuated at the metal surface. The difference between p- and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential. In contrast, two other popular in situ IR spectroscopic techniques, namely, subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) …

Redox-Active Monolayers On Ito Prepared By Post-Amidation And Direct Esterification And Their Spectroelectrochemical Characterization, Takamasa Sagara, Sae Nakai, Ryusuke Yofu, Shota Kojin

Journal of Electrochemistry

A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing. The necessity for its sophistication arises from the availability of multi-dimensional sensing signals. Simultaneous monitoring of the redox current and color change synchronized with the oxidation state change significantly enhances sensitivity and selectivity. This study aimed to elucidate the modification of an indium tin oxide (ITO) electrode with a viologen monolayer with an ordered orientation. Novel methods were developed to immobilize a viologen molecule bearing a carboxyl group to form assembled monolayers through a condensation reaction using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide with N-hydroxy-succinimide (EDC/NHS). In the two methods …

A Promising Statistical Approach For Studying The Collisional Excitation Induced By Co: Application To The Cs-Co System, Amélie Godard Palluet, Richard Dawes, Ernesto Quintas-Sánchez, Adrian Batista-Planas, François Lique

Chemistry Faculty Research & Creative Works

The calculations of rate coefficients for the interpretation of molecular spectra are a recognized computationally expensive task. This is particularly true for media like comets, where the dominant species (CO, CO₂, and H₂O) have relatively high masses. Currently, no clear methodology exists to treat the collisional excitation of heavy species at low temperatures, thus limiting the number of collisional studies on such species. We present here a promising statistical approach to determine collisional rate coefficients of heavy systems as an alternative to fully quantum calculations when heavy projectiles such as CO are considered. This is illustrated …

Ambient Co2 Capture And Valorization Enabled By Tandem Electrolysis Using Solid-State Electrolyte Reactor, Yan-Bo Hua, Bao-Xin Ni, Kun Jiang

Journal of Electrochemistry

Electrocatalytic carbon dioxide reduction is a promising technology for addressing global energy and environmental crises. However, its practical application faces two critical challenges: the complex and energy-intensive process of separating mixed reduction products and the economic viability of the carbon sources (reactants) used. To tackle these challenges simultaneously, solid-state electrolyte (SSE) reactors are emerging as a promising solution. In this review, we focus on the feasibility of applying SSE for tandem electrochemical CO₂ capture and conversion. The configurations and fundamental principles of SSE reactors are first discussed, followed by an introduction to its applications in these two specific areas, …

Characterizing Electrospray Performance Of Hydroxylammonium Nitrate (Han) And 2-Hydroxyethylhydrazinium Nitrate (Hehn) Ionic Liquids By Mass Spectrometry And Dynamics Simulations, Wenjing Zhou

Dissertations, Theses, and Capstone Projects

Dual-mode propulsion combines chemical and electric propulsion methods into a single compact system by sharing hardware and propellant for both modes, offering complementary advantages tailored to specific mission needs. A promising propellant candidate for dual-mode propulsion is a binary mixture of hydroxylammonium nitrate (HAN) and 2-hydroxyethylhydrazinium nitrate (HEHN) ionic liquids (ILs). Each of the two ILs was developed as a greener alternative to the traditional, yet toxic, hydrazine monopropellant used in chemical propulsion. Recently, their potentials in electrospray propulsion have garnered attention. This thesis focused on the investigation of reaction dynamics and kinetics of HAN, HEHN and their binary mixture …