Digital Commons Network^™

Effects Of Varying Ph, Temperature, And Sucrose Concentration On The Activity Of Invertase Enzyme, B. Rainwater, S. Pratihar

Journal of the Arkansas Academy of Science

The purpose of this research is to study the factors that affect the enzymatic activity of invertase, extracted from baker’s yeast, on hydrolysis of sucrose in aqueous medium. Invertase, a glycoprotein, is an enzyme in the glycoside hydrolase family. It catalyzes the hydrolysis of sucrose producing equimolar mixture of a-D-glucose and b-D-fructose. Invertase shows high affinity for the substrate, and is capable of both cleaving the glycosidic linkage in sucrose and transferring ab-D-O-fructofuranoside residue to an acceptor substrate. (Toledo et al. 2019). A detailed mechanism of the action of invertase was postulated by Shall et al. (Shall et al. 1971). …

Simulating Chemiluminescence Spectra Of Oh Radical Using Quantum Dynamical Simulations, Triet M. Cao

Research from the Berry Summer Thesis Institute, 2025

Chemiluminescence is a phenomenon of light emission that occurs when molecules transition from an excited state to the ground state. This phenomenon is widely utilized in applications ranging from quantifying product yields in chemical reactions to biological imaging and atmospheric chemistry studies. It has also been used in many crucial applications in the scarce conditions of heat and electricity, such as light sources for astronomy discovery or deep-sea diving. A notable example of such reactions is combustion, where highly reactive hydroxyl radicals (OH) are products. These radicals exhibit a chemiluminescence spectrum because of the interaction between their ground state and …

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 …

Investigating The Photophysical Dynamics Of Anthracene And Acridine Derivatives Using Time-Resolved Spectroscopy, Sophia Tiano

Open Access Dissertations

Anthracenes and acridines are among the simplest visible light absorbing heterocyclic and polycyclic aromatic hydrocarbons and as such are extensively used in a variety of applications including photosensitizers and fluorescent sensors. Although the photophysics of some derivatives have been studied in the past, there is still a lot of unknown fundamental information that is vital in order to optimize these molecules for particular applications. Transient absorption spectroscopy was used to study the photophysics of the 9-substituted methyl, hydroxymethyl and formyl derivatives of acridine and anthracene. The growth and decay of the triplet-triplet absorption peak were quantified for each dye in …

Intrinsic Gas-Phase Behavior Of Uranium Species: A Comprehensive Reactivity Study Of [O=U≡Ch]+ And [Uh]+, Justin Terhorst

Electronic Theses and Dissertations

The intrinsic chemistry of actinide elements, particularly uranium, remains a key challenge in understanding f-block reactivity due to the complexity introduced by solvent interactions, counter-ions, and complex equilibria in the condensed phase. In this dissertation, a systematic gas-phase study utilizing preparative tandem ion-trap mass spectrometry (PTMSⁿ) is presented, focusing on the reactivity of uranium-centered species, specifically [OUCH]⁺, an oxy uranium methylidyne species, and [UH]⁺ ions. By stripping away solvent effects and isolating the ions, PTMSⁿ provides a powerful platform to probe the fundamental chemical behavior of uranium species in their intrinsic state.

The …

Theoretical Studies Of Benzoquinone Reactivity In Acidic And Basic Environments, Natali Majoras

Honors Theses

Quinones are a class of organic compounds containing a six-membered unsaturated ring with two carbonyl groups. They are biologically relevant mostly due to their ability to participate in redox reactions. Prior experiments in our lab showed that quinones can induce protein modifications that are pH dependent. In an acidic environment the modifications were less significant than in a basic environment. Previous computational studies have also been carried out to model, in neutral solutions, the reaction between various quinones and various amines. Various amine groups are used as a model for the amino group of lysine to represent protein modification. The …

Heterogeneous Oxidation Of Multi-Component Aqueous Organic Aerosols: The Effect Of Transport Phenomena And Reaction Compartment On Reaction Kinetics., Tadini Wenyika Masaya

Graduate Theses, Dissertations, and Problem Reports (ETD)

The surface-bulk partitioning of small organic molecules in aqueous droplets was investigated using molecular dynamics. The air-particle interface was modeled using a 80-Å cubic water box containing series of organic molecules and surrounded by gaseous OH radicals. The properties of the organic solutes within the interface and the water-bulk were examined at a molecular-level using density profiles and radial pair distribution functions. Molecules containing only polar functional groups such as urea and glucose are found predominantly in the water bulk, forming an exclusion layer near the water surface. Substitution of a single polar group by an alkyl group in sugars …

Characterization Of The Ch Addition Product From Meta- And Ortho-Xylene + Ch Reaction And Direct Experimental Observation Of The Tetrabromine Cluster Br4 Using Synchrotron Photoionization Mass Spectrometry, Rory R. Mcclish

Master's Theses

This thesis is centered on the use of a unique gas-phase spectroscopy technique to characterize products and elucidate reaction mechanisms. Experiments were carried out at the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source located at the Lawrence Berkeley National Laboratory in Berkeley, CA. Computational work was performed on the scientific supercomputer at USF to supplement experimental findings. Chapter 1 contextualizes the work spurred in response to the deleterious interactions of anthropogenic emissions on Earth’s climate. Chapter 2 describes the theoretical manipulations foundational to the experimental design and interpretation. Chapter 3 delves into the physical details of the experimental …

Modeling Vitexin And Isovitexin Flavones As Corrosion Inhibitors For Aluminium Metal, Abdullahi Muhammad Ayuba, Umaru Umar

Karbala International Journal of Modern Science

Theoretically, the aluminium corrosion inhibitive performance of vitexin (VTX) and isovitexin (SVT) were evaluated with a view of establishing the mechanism of the inhibition process. Calculations which include the consideration of several global descriptors were studied to describe and correlate the reactivity of the molecules with the computed descriptors. First and second-order condensed Fukui functions were employed to analyze local reactivity parameters, while simulations involving the adsorbed molecules on Al (1 1 0) surface were conducted through quench dynamic simulations and the mechanism of physical adsorption was established with SVT relatively been a better inhibitor on Al surface than VTX.

Water-Mediated Peptide Bond Formation In The Gas Phase: A Model Prebiotic Reaction, George C. Shields, Ariel Gale, Tuguldur T. Odbadrakh, Tyler Ball

Chemistry Publications

The emergence of life on the prebiotic Earth must have involved the formation of polypeptides, yet the polymerization of amino acids is thermodynamically unfavorable under biologically relevant aqueous conditions because amino acids are zwitterions in solution and because of the production of a water molecule through a condensation reaction. Many mechanisms for overcoming this thermodynamic unfavorability have been proposed, but the role of gas phase water clusters has not been investigated. We present the thermodynamics of the water-mediated gas phase dimerization reaction of glycine as a model for the atmospheric polymerization of amino acids prior to the emergence of biological …

Computational Quantum Chemistry Studies Of The Interactions Of Amino Acids Side Chains With The Guanine Radical Cation., Edward Acheampong

Electronic Theses and Dissertations

Guanine is generally accepted as the most easily oxidized DNA base when cells are subjected to ionizing radiation, photoionization or photosensitization. At pH 7, the midpoint reduction potential is on the order of 0.2 – 0.3 V higher than those of the radicals of e.g. tyrosine, tryptophan cysteine and histidine, so that the radical “repair” (or at least, a thermodynamically favorable reaction) involving these amino acids is feasible. Computational quantum studies have been done on tyrosine, tryptophan, cysteine and histidine side chains as they appear in histones. Density functional theory was employed using B3LYP/6-31G+ (d, p) basis set to study …

Radical Chemistry In A Femtosecond Laser Plasma: Photochemical Reduction Of Ag+ In Liquid Ammonia Solution, Victoria K. Meader, Mallory G. John, Laysa M. Frias Batista, Syeda Ahsan, Katharine M. Tibbetts

Chemistry Publications

Plasmas with dense concentrations of reactive species such as hydrated electrons and hydroxyl radicals are generated from focusing intense femtosecond laser pulses into aqueous media. These radical species can reduce metal ions such as Au3+ to form metal nanoparticles (NPs). However, the formation of H2O2 by the recombination of hydroxyl radicals inhibits the reduction of Ag+ through back-oxidation. This work has explored the control of hydroxyl radical chemistry in a femtosecond laser-generated plasma through the addition of liquid ammonia. The irradiation of liquid ammonia solutions resulted in a reaction between NH3 and OH·, forming peroxynitrite and ONOO−, and significantly reducing …

Avoiding The Cubic Equation In Finding The Van Der Waals Fluid's Vapor Pressures, Carl W. David

Chemistry Education Materials

The van der Waals coexistence curve of liquid and vapor volumes as functions of the temperature (all in reduced coordinates) as well as the correspponding vapor pressures at these temperatures, is obtained using SageMath, a symbolic calculus/algebra computer programming language.The lack of correspondence of the coexistence locus’ analytical form as obtained herein and those of Lekner remains disconcerting.

Computational Quantum Chemistry Studies Of The Stabilities Of Radical Intermediates Formed During The Oxidation Of Melatonin, Constance E. Warden

Electronic Theses and Dissertations

Melatonin, a nontoxic natural antioxidant, is of interest as a possible spin trap for use in spectroscopic methods to observe and identify short-lived free radicals, which have been linked to oxidative stress that may result in serious health problems. However, the reaction mechanisms for the oxidation of melatonin to form the product N¹-acetyl-N²-formyl-5-methoxykynuramine are still not well understood. Computational quantum chemistry studies have been done on four proposed reaction mechanisms, involving the following major intermediate structures: a dioxetane, an epoxide, a melatonin radical cation, and a spin radical adduct. Molecular geometries were optimized at the …

Theoretical Study Of Photoelectrochemical Reactions And Ec-Sers On Spr Metallic Electrodes Of Silver And Gold, Yuan-Fei Wu, Ran Pang, Meng Zhang, Jian-Zhang Zhou, Bin Ren, Zhong-Qun Tian, De-Yin Wu

Journal of Electrochemistry

At present photoelectrochemistry has received much concern back to nanostructures of noble metals from semiconductor electrodes. This is due to the surface plasmon resonance (SPR) effect of metallic nanostructures, which can effectively convert the far-field light to the near-field light and concentrate the photonic energy to the local surface area with high energy density. Thus, the different enhancement mechanisms, such as the local optical field enhancement, the formation of light generated hot carriers (hot electron-hole pairs), or the photothermal effect, have been proposed in literatures. On the basis of the SPR enhancement effect, the surface-enhanced Raman spectroscopy (SERS) can be …

Computational Studies Of Spin Trapping Of Biologically Relevant Radicals By New Heteroaryl Nitrones, Eyram Asempa

Electronic Theses and Dissertations

Heteroaryl nitrone spin traps have been suggested to act as free radical scavengers. The geometry optimizations and the single-point energies of the spin trapping reactions of the heteroaryl nitrones, 5,5-dimethylpyrroline-N-oxide (DMPO) and α-phenyl-N-t-butylnitrone (PBN) have been computationally studied using ab initio (Hartree-Fock (HF) and second-order Møller-Plesset (MP2)) methods and Density Functional Theory (DFT) methods. The effects of new heteroaryl substituents on a parent nitrone spin trap have been examined at the HF and MP2 levels with the 6-31G*, and cc-pVnZ (n=D, T, Q) basis sets. The thermodynamics of the spin trapping at the C-site and O-site with •H, …

Electrochemical Behavior Of Dill Pipe In 31%(By Mass) Nacl Solution Based New Type Inhibitor, Fu-Guo Liu, Min Du, Qing-Zhang Wang

Journal of Electrochemistry

The inhibitive effect of compound inhibitor including emulsifier(P), zinc sulfate, sodium polyphosphate, Glucose Gluconate was studied in 31% NaCl (by mass) solution. The inhibitory mechanism was analyzed by polarization curve and EIS. The results showed that the compound inhibitor was anodic-type inhibitor and its inhibitive effect on anodic and cathodal reaction was the most obvious at 200×10-6g·L^-1. And the results of EIS revealed that the inhibition efficiency increased and the film formed on electrode surface was more and more compact with time. Inhibition mechanism was different with concentration of inhibitor.

Solution-Based Synthesis Of Nitride Fuels, Kenneth Czerwinski, Thomas Hartmann

Fuels Campaign (TRP)

A wide variety of fuel concepts are considered for advanced reactor technology including metals, metal oxides or metal nitrides as solid solutions or composite materials. Nitride fuels have appropriate properties for advanced fuels including high thermal conductivity, thermal stability, solid-state solubility of actinides, fissile metal density, and suitable neutronic properties. A drawback of nitride fuels involves their synthesis. A key parameter for preparing oxide fuels is the precipitation step in the sol-gel process. For nitride fuels, the current synthetic route is carbothermic reduction from the oxide to the nitride. This process step is based on solid phase reactions and for …

Atomic And Molecular-Perspectives In Electrochemical Interfaces, Zhaowu Tian

Journal of Electrochemistry

The following recent studies on the atomic and molecular-perspectives at electrochemical interfaces using Raman, IR, STM and quantum chemical methed by electrochemistry group in Xiamen University are briefly reviewed. 1.Orientation, charge transfer and bonding of adsorbed molecules. 2. Adsorption effect, electrode potential effect and adatom effect on the electron populations and strength of intramolec ular bonds of the adsorbed molecules. 3. Detailed classification into various types (e. g., competitive, chemically inductive, physical inductive etc.) of coadsorption on electrodes according to the above-mentioned effects.  4. Single crystal face structure effect and adatom effect on the kinetics and the mechanisms of electrocatalytic …

On The Mechanism Of The Diels-Alder Reaction--Dimerization Of Trans-Phenylbutadiene, Michael Ward Mcnicholas

Dissertations and Theses

The Diels-Alder dimerization of trans-1-substituted butadienes is expected to yield a cyclohexene adduct with the substituents in the 3 and 4 positions cis to one another. This prediction is based on past observations of other Diels-Alder additions. The cis-isomer is the only one consistent with a two-stage mechanism proposed by Woodward and Katz.

In the case of trans-phenylbutadiene, the expected adduct is cis-3-phenyl 1-4-(trans-styry1) cyclohexene. Alder, Haydn and Vogt, however, reported that the corresponding trans-isomer is the dimerization product. There is reason to believe that the observation of the trans-isomer may have been the result of product isomerization during purification. …

Water Chemistry Survey Of Boulder Basin, Lake Mead, P. R. Tramutt, Bureau Of Reclamation

Publications (WR)

The survey results indicate that the impoundment of water behind Hoover Dam has not adversely affected the dissolved oxygen (DO) content and that water quality and DO content were uniform regardless of depth. The study made in April-May 1964 will provide water quality data of Lake Mead prior to releases from Lake Powell as a basis for evaluating Lake Powell's effect on water quality and limnology of Lake Mead. The performance of a DO analyzer was tested and found unsatisfactory at depths below 150 ft. Parameters tested by standard chemical analyses of water samples in the Denver Laboratory and by …