Computational Quantum Chemistry Studies Of The Interactions Of Amino Acids Side Chains With The Guanine Radical Cation., 2018 East Tennessee State Universtiy
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 ...
Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, 2018 University of Kentucky
Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman
Chemistry Faculty Publications
Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic ...
Hydrogen-Deuterium Exchange Mass Spectrometry And Molecular Dynamics Simulations For Studying Protein Structure And Dynamics, 2018 The University of Western Ontario
Hydrogen-Deuterium Exchange Mass Spectrometry And Molecular Dynamics Simulations For Studying Protein Structure And Dynamics, Yiming Xiao
Electronic Thesis and Dissertation Repository
Deciphering properties of proteins are essential for human health and aiding in the development of new pharmaceuticals. This dissertation uses hydrogen-deuterium exchange (HDX) mass spectrometry (MS) and molecular dynamics (MD) simulations to study protein dynamics, for improving the understanding of protein folding/unfolding mechanisms, and ligand binding and allosteric regulation.
Chapter 2 uses HDX-MS for probing the conformational dynamics of myoglobin in the presence of N2 bubbles. We propose a dynamic model that reproduces the observed data: “semi-unfolded” “native” “globally unfolded” -> “aggregated”. Chapter 3 focuses on osteoprotegerin (OPG), which hinders bone resorption by inhibiting RANK/RANKL interactions. The dimerization ...
Mechanism Of Protein Charging And Supercharging In Electrospray Ionization: Molecular Dynamics Simulations And Experimental Investigations, 2018 The University of Western Ontario
Mechanism Of Protein Charging And Supercharging In Electrospray Ionization: Molecular Dynamics Simulations And Experimental Investigations, Haidy S. Metwally
Electronic Thesis and Dissertation Repository
Electrospray ionization mass spectrometry (ESI-MS) is a powerful technique for investigating protein structures, conformations, and interactions. Despite its widespread use, many fundamental aspects of ESI remain poorly understood. In this thesis, we use a combination of molecular dynamics (MD) simulations and experiments to gain insights into the hidden complexities of ESI-MS.
Chapter 2 discusses the topic of salt-induced protein signal degradation. Salts such as NaCl, CsCl, and tetrabutyl ammonium chloride (NBu4Cl) interfere with MS data acquisition, leading to adduct formation and signal suppression. MD simulations provide an explanation for these salt interferences. Signal suppression can be broken down ...
An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, 2018 University of Kentucky
An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman
Chemistry Faculty Publications
Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric ...
Nuclear Magnetic Resonance Studies Of Imidazolium-Based Ionic Liquids And Garnet-Type Li7la3zr2o12, 2018 The Graduate Center, City University of New York
Nuclear Magnetic Resonance Studies Of Imidazolium-Based Ionic Liquids And Garnet-Type Li7la3zr2o12, Shen Lai
All Dissertations, Theses, and Capstone Projects
Advancements in electrochemical energy storage materials are critical in the development and utilization of renewable energy technologies. These advancements involve obtaining a better understanding of electrochemical mechanisms and properties through scientific research towards an improved energy storage technology. Nuclear magnetic resonance (NMR), is a sensitive and selective method to probe particle dynamics (magnetic relaxation, diffusometry, etc.) and material structures (spectroscopy) down to the atomic level. In this work, several NMR techniques are employed to study imidazolium-based ionic liquids and garnet-type inorganic materials. These are being studied due to their potential use as safer alternatives to organic solvent-based electrolytes in lithium-ion ...
Nascent O2 (A1ΔG, V = 0, 1) Rotational Distributions From The Photodissociation Of Jet‐Cooled O3 In The Hartley Band, 2018 Texas A & M University - College Station
Nascent O2 (A1ΔG, V = 0, 1) Rotational Distributions From The Photodissociation Of Jet‐Cooled O3 In The Hartley Band, Michelle L. Warter, Carolyn E. Gunthardt, Wei Wei, George Mcbane, Simon W. North
Peer Reviewed Articles
We report rotational distributions for the O2 (a 1Δg) fragment from photodissociation of jet‐cooled O3 at 248, 266, and 282 nm. The rotational distributions show a population alternation that favors the even states, as previously reported for a 300 K sample by Valentini et al. (J. Chem. Phys. 86, 6745 (1987)). The alternation from the jet‐cooled precursor is much stronger than that observed by Valentini et al., and in contrast to their observations does not depend strongly on O2 (a 1Δg) vibrational state or photolysis wavelength. The odd/even alternation diminishes ...
Building On Nature: Spectroscopic Studies Of Photosynthesis-Inspired Pigments, Fused Light Harvesting Proteins, And Bacterial Reaction Center Mutants, 2018 Washington University in St. Louis
Building On Nature: Spectroscopic Studies Of Photosynthesis-Inspired Pigments, Fused Light Harvesting Proteins, And Bacterial Reaction Center Mutants, Kaitlyn Faries
Arts & Sciences Electronic Theses and Dissertations
Photosynthesis is the dominant form of solar energy conversion on the planet, making it critical to understand the fundamentals of the process in order to effectively mimic and improve upon it for human energy needs. The initial stages of photosynthesis include light harvesting and chemical conversion of that harvested energy via electron transport, with both of these stages relying on pigments (or chromophores) such as chlorophyll and specific protein architectures for the processes. In this work, the fundamental underpinnings of photosynthetic light harvesting and electron transport are explored via spectroscopy of various photosynthetic systems with altered natural pigments and proteins ...
Materials Characterization By Dynamic Nuclear Polarization Enhanced Solid-State Nmr Spectroscopy, 2018 Iowa State University and Ames Laboratory
Materials Characterization By Dynamic Nuclear Polarization Enhanced Solid-State Nmr Spectroscopy, Aaron Rossini
High-resolution solid-state NMR spectroscopy is a powerful tool for the study of organic and inorganic materials because it can directly probe the symmetry and structure at nuclear sites, the connectivity/bonding of atoms and precisely measure inter-atomic distances. However, NMR spectroscopy is hampered by intrinsically poor sensitivity, consequently, the application of NMR spectroscopy to many solid materials is often infeasible. High-field dynamic nuclear polarization (DNP) has emerged as a technique to routinely enhance the sensitivity of solid-state NMR experiments by one to three orders of magnitude. This perspective gives a general overview of how DNP enables advanced solid-state NMR experiments ...
Cation-Π Interactions Of Selected Alkali Metal Ions With Two Benzene Rings Connected Through Linear Chains, 2018 Clark Atlanta University
Cation-Π Interactions Of Selected Alkali Metal Ions With Two Benzene Rings Connected Through Linear Chains, Nouf Alshamrani
Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University
Quantum chemical calculations at M06-2X/6-311+G(2d,2p) level were employed to examine the structures, dissociation energies and vibrational spectra of complexes formed by Li+, Na+ and K+ with diphenylmethane, 1,2-diphenylethane, 1,3-diphenylpropane, [2.2]paracyclophane and [3.3]paracyclophane molecules. The effect of heteroatom substitution in the connecting chains of 1,3-diphenylpropane and [3.3]paracyclophane molecules on the binding affinity of cations with ligands was also included in this study. The complexes of [3.3] paracyclophane based molecules seem to have weak cation-pi interactions with metal ions Na+ and K+ when they were placed between two ...
Enhanced Acidity Of Acetic And Pyruvic Acids On The Surface Of Water, 2018 University of Kentucky
Enhanced Acidity Of Acetic And Pyruvic Acids On The Surface Of Water, Alexis J. Eugene, Elizabeth A. Pillar, Agustín J. Colussi, Marcelo I. Guzman
Chemistry Faculty Publications
Understanding the acid–base behavior of carboxylic acids on aqueous interfaces is a fundamental issue in nature. Surface processes involving carboxylic acids such as acetic and pyruvic acids play roles in (1) the transport of nutrients through cell membranes, (2) the cycling of metabolites relevant to the origin of life, and (3) the photooxidative processing of biogenic and anthropogenic emissions in aerosols and atmospheric waters. Here, we report that 50% of gaseous acetic acid and pyruvic acid molecules transfer a proton to the surface of water at pH 2.8 and 1.8 units lower than their respective acidity constants ...
Infra-Red Microwave Spectra, Overtones, Degeneracy And Thermal Populations All In One Diagram, 2018 University of Connecticut
Infra-Red Microwave Spectra, Overtones, Degeneracy And Thermal Populations All In One Diagram, Carl W. David
Chemistry Education Materials
An old drawing, which had an error in it, is re-presented (corrected) for understanding the relationships in diatomic vibrational-rotational interactions at the introductory level.
Novel Relative Spontaneous Ignition Temperature Determination Using Carbon Dioxide Onset With Sta/Ir, 2018 Stephen F. Austin State University
Novel Relative Spontaneous Ignition Temperature Determination Using Carbon Dioxide Onset With Sta/Ir, Antonio David Trevino
Electronic Theses and Dissertations
Simultaneous thermal analysis, coupled with infrared spectroscopy (STA/IR), was utilized to monitor the evolution of gaseous products during the thermal degradation of samples from Triadica sebifera (Chinese tallow), Ligustrum sinense (Chinese privet), and Ilex vomitoria (yaupon) plants. Identification of carbon dioxide was successful with a spectral match of 90.2 percent and further used in the determination of relative spontaneous ignition temperature, or RSIT. The RSIT value during the growing season for Chinese tallow, Chinese tallow stem, Chinese privet, and Yaupon were 208.4°C, 250.3°C, 210.1°C, and 232.3°C respectively. During the dormant ...
Modern Electronic Structure Theory: The Search For Chemical Accuracy, 2018 Boise State University
Modern Electronic Structure Theory: The Search For Chemical Accuracy, Jonathan Prince
Boise State University Theses and Dissertations
Electronic structure theory has progressed significantly within the last few decades, venturing far from the early days of the Hartree-Fock self-consistent field method. Modern electronic structure theory focuses on compound methods, which operate under the idea that we can take a lower level of theory computation (typically, a result from Hartree-Fock, Configuration Interaction, Coupled Cluster or Moller-Plesset perturbation theory) and add in higher level of the theory corrections such as extrapolations to the infinite basis set limit, as well as, relativistic effects.
Using the Gaussian-n, Complete Basis Set and Weizmann compound methods, we were able to provide theoretical evidence to ...
Nmr Spectroscopic Properties Of Nucleotides, And A New Method Of Numeric Calculation Of Raman Intensities For Organic Molecules, 2018 Missouri State University
Nmr Spectroscopic Properties Of Nucleotides, And A New Method Of Numeric Calculation Of Raman Intensities For Organic Molecules, William R. Ehrhardt
MSU Graduate Theses
General and accurate computational methodologies are currently lacking for large chemical systems. This is primarily due to the computational expense required to perform calculations on systems with one hundred or more atoms. Calculated spectroscopic properties could aid in the process of elucidating structural features of large biologically relevant molecules if accurate and inexpensive methods are developed. Towards this end the first steps were taken to design a general methodology for predicting NMR chemical shifts of large nucleic acid systems. It was found that HF and semi-empirical methods were not sufficient for optimization of nucleobases, and therefore larger nucleotide or nucleic ...
Ultrafast And Nonlinear Spectroscopy Of Nanomaterials, 2018 Louisiana State University and Agricultural and Mechanical College
Ultrafast And Nonlinear Spectroscopy Of Nanomaterials, Rami Anthony Khoury
LSU Doctoral Dissertations
Ultrafast and nonlinear spectroscopies are implemented in the investigation of excited-state dynamics and structural properties of materials and nanomaterials. In the first study, the excited-state dynamics of size-dependent colloidal TiO2-Au nanocomposites are investigated using ultrafast transient absorption spectroscopy. The dynamics corresponding to the plasmon depletion band are characterized by electron-phonon and phonon-phonon coupling lifetimes that are observed to be independent of the gold nanocluster shell thickness. The excited-state dynamics corresponding to the interband transition of gold is also spectrally overlapped with the interfacial electron transfer lifetime, which is shown to decrease as the nanocluster shell thickness increases. In ...
The Commutator Of The Runge Lenz Vector With Other Operators Of The H-Atoms Physics Using Maxima, 2018 University of Connecticut
The Commutator Of The Runge Lenz Vector With Other Operators Of The H-Atoms Physics Using Maxima, Carl W. David
Chemistry Education Materials
Commutators of components of the Runge-Lenz vector and constants of the motion and ladder operators for the H-atom problem are evaluated using brute force calculus and Maxima.
Investigation Of Vaporization Enthalpies And Vapor Pressures Of Organic Compounds By Correlation Gas Chromatography, 2018 University of Missouri, St. Louis
Investigation Of Vaporization Enthalpies And Vapor Pressures Of Organic Compounds By Correlation Gas Chromatography, Carissa Nelson
Thermodynamic properties of organic compounds are useful to scientists and manufacturers in many areas of research and technology. This work focuses on measuring and reporting these properties on materials of commercial, environmental and scientific interest. Vaporization enthalpies and vapor pressures of several organic compounds have been studied using correlation gas chromatography (CGC) and are reported here as well as in recent publications. The CGC method allows for the indirect measurement of these properties in instances where these materials are available only in mixtures or in very small amounts.
The qualities of these measurements for any chosen target are directly related ...
The Photodynamic And Structural Analyses Of Advanced Materials For Solar Fuel Conversion, 2018 Marquette University
The Photodynamic And Structural Analyses Of Advanced Materials For Solar Fuel Conversion, Brian Pattengale
Dissertations (2009 -)
Mitigating the current and future climate and pollution issues that have been brought on by the combustion of fossil fuels is of utmost importance and will rely on, in part, the availability of renewable fuel sources. Of the possible sources of energy, solar is abundant, but must be harnessed efficiently and stored as a solar fuel to overcome the current storage issues that limit photovoltaic cells. One such fuel, H2(g), represents a carbon-neutral source of energy if it can be efficiently liberated from water via the water splitting reaction. Thus, much attention is focused on designing materials to perform ...
Study Of The Visual Adaptation Mechanism In Marine Species With The Change Of Habitation Depth., 2018 Physical-Technical High School
Study Of The Visual Adaptation Mechanism In Marine Species With The Change Of Habitation Depth., Demid Osipov, Daniil Moshnikov
The International Student Science Fair 2018
The goal of our work was to determine the principal mechanisms that provide the difference in visual perception of two marine species that live on different depths: T. Pacificus and O. Vulgaris. In nature, visual perception of species that live deeper is shifted towards the blue region. This is related to the fact that red, orange and yellow light is absorbed more strongly by water than the blue light. On the other hand, the visual perception spectrum of an animal is determined by the absorption spectrum of the "light sensor" located in rods and cones of its eye retina. These ...