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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Role Of Defect Type In Optimizing Photoelectrochemical Hydrogen Production Catalysts, Mohamed Mahrous
Role Of Defect Type In Optimizing Photoelectrochemical Hydrogen Production Catalysts, Mohamed Mahrous
Theses and Dissertations
The search for new energy sources has become a global challenge due to the increasing demand for energy and the negative impact of traditional energy sources on the environment. The photoelectrochemical water splitting has emerged as a promising alternative source for producing hydrogen, which can be used as a clean fuel. However, it is necessary to tailor the properties of the light-active material that will be used to absorb sunlight and split water. This research project aimed at providing detailed insights into the effect of varying the type and concentration of defects on the optical and electronic properties of diamond …
Atomistic Assessment Of Drug-Phospholipid Interactions Consequent To Cancer Treatment: A Study Of Anthracycline Cardiotoxicity, Yara Elsayed Ahmed
Atomistic Assessment Of Drug-Phospholipid Interactions Consequent To Cancer Treatment: A Study Of Anthracycline Cardiotoxicity, Yara Elsayed Ahmed
Theses and Dissertations
Despite being one of the most effective chemotherapeutic agents developed to date, Anthracyclines are notorious for their cardiotoxicity. Their clinical use is frequently limited both in dosage and in prescription due to the severe cardiac damage they cause. The mechanism of anthracycline-induced cardiotoxicity is not yet fully understood. However, it is hypothesized that interactions with the myocardial membrane play an important role in imparting cardiotoxicity. In this study, we use molecular dynamics simulations and density functional theory calculations to study the anthracycline drug molecules and the interactions that they have with the myocardial membrane. We construct a myocardial membrane model …
Structural Analysis Of [Ni(Dippe)] Fragment Using Computational Methods, Jennifer L. Sanchez
Structural Analysis Of [Ni(Dippe)] Fragment Using Computational Methods, Jennifer L. Sanchez
Theses and Dissertations
The structural analysis of the Nickel (Bisdiisopropylphospino)ethane, also known as [Ni(dippe)H]2, has been heavily studied in our group in collaboration with William D. Jones's group. A computational analysis of the [Ni(dippe)] fragment was performed to determine the structural relationship between the nickel center and its phosphine ligand, due to phosphines having both electronic and steric properties. The reactivity of the Nickel will be most dependent on the dippe ligand. A conformational search generated 244 conformers after a thorough minimization using Molecular Mechanic (MM) calculations where a thorough minimization was performed and then re-minimized using a SEED command until unique conformers …
Computationally Assisted Nmr Crystallography: A Path To Unusually High-Resolution Crystal Structures, Luther Wang
Computationally Assisted Nmr Crystallography: A Path To Unusually High-Resolution Crystal Structures, Luther Wang
Theses and Dissertations
Crystallography has traditionally been studied by diffraction methods involving X ray or neutron radiation. These methods have some limitations, from requiring the substance under study to form single crystals to the limited ability of X rays to locate hydrogen atoms. While neutron radiation can characterize hydrogens, it is expensive, not readily available and has its own particular limits on resolution. It this dissertation, it is demonstrated that NMR is extraordinarily sensitive to atomic positions, with variations of mere tens of femtometers creating statistically distinguishable chemical shift changes. To date, no other means of measurement can detect structural changes at this …
Quantum Capacitance Investigation Of Different Tas2 Polymorphs For Energy Storage Applications – First Principles Study, Mahmoud Elattar
Quantum Capacitance Investigation Of Different Tas2 Polymorphs For Energy Storage Applications – First Principles Study, Mahmoud Elattar
Theses and Dissertations
Energy is an essential requirement, which has a growing demand due to the growth of population and the world transformation into electronic. More than 70% of energy resources are fossil-fuel based which has an environmental impact due to the CO2 emissions. Energy hubs for Fossil-fuel to electric energy conversion, controlled CO2 emissions processing units, and energy storage system are key factors for a smooth transition to green energy without lack of energy supplies, where electrical energy storage systems (ESS) are key enablers to achieve that. One of the effective components which determines the ESS efficiency is the electrode …
Investigation Of The C—Cn Bond Activation Of Fluorinated Benzonitriles With [Ni(Dmpe)] And Dft Benchmarking Study With [Ni(Dippe)], Dominique C. Gallegos
Investigation Of The C—Cn Bond Activation Of Fluorinated Benzonitriles With [Ni(Dmpe)] And Dft Benchmarking Study With [Ni(Dippe)], Dominique C. Gallegos
Theses and Dissertations
Carbon-carbon bond activation has become a rapidly growing area of research due to its extensive range of applications. Despite the significant progress that has been made in this field, the cleavage of kinetically inert and thermodynamically stable C—C σ-bonds under mild homogeneous conditions remains a challenge. The activation is primarily limited to systems in which either relief of strain or aromatization serves as a driving force. A notable exception to this is the oxidative addition of unstrained C—CN bonds of nitriles. In this study, we are looking at the effect of fluoro substituents. We hypothesized …
Computational Study Of Radical Cation Rearrangements, Mi'kayla D. Word
Computational Study Of Radical Cation Rearrangements, Mi'kayla D. Word
Theses and Dissertations
A radical cation is a molecule that has one unpaired electron that holds a positive charge. The unpaired electron within a radical cation causes the molecule to be reactive. The high reactivity of these species allows for radical cations to be commonly studied experimentally using mass spectrometry and other multi-mass imaging techniques. However, these methods often cannot resolve the reaction mechanisms for these fast reactions. Specifically, radical cation rearrangement mechanisms are particularly unresolved within experiments. For this reason, radical cation rearrangements are computationally investigated to explain complex reaction pathways for processes to understand reactions leading to the initiation of detonation …
A Density Functional Theory Study Of Palladium Nanoparticles And Their Redox Properties On Graphene, Billie A. Radcliffe
A Density Functional Theory Study Of Palladium Nanoparticles And Their Redox Properties On Graphene, Billie A. Radcliffe
Theses and Dissertations
Nanoparticles exhibit characteristics that are different from bulk materials as well as from atoms resulting in their application in numerous fields of applied material science. In particular, small palladium nanoparticles supported on graphene have been found to be outstanding catalysts for the Suzuki cross-coupling reaction. One explanation as to why these supported nanoparticles are such outstanding catalysts is because they may act as both electron donors and acceptors. Charge donating ligands are known to lower the ionization energy of clusters, making the clusters better donors. In this project, it is hypothesized that graphene supports may also act like charge donating …
Computational Design And Analysis Of Molecular Ethylene Oligomerization Catalysts, Doo Hyun Kwon
Computational Design And Analysis Of Molecular Ethylene Oligomerization Catalysts, Doo Hyun Kwon
Theses and Dissertations
Linear alpha olefins (LAOs) are key petrochemical precursors for the synthesis of larger polymers, detergents, plasticizers, and lubricants. Most catalytic ethylene oligomerization processes generate a wide distribution of LAO carbon chain lengths. A major ongoing industrial challenge is to develop homogeneous catalysts that result in selective and tunable ethylene oligomerization to 1-hexene and 1-octene alkenes. Quantum mechanical calculations coupled with rapidly advancing technology have enabled the ability to calculate small molecule systems with high accuracy. Employing computational models to advance from empirical to quantitative prediction of product selectivities has become an active area of exploration. In this work, we demonstrate …
Electronic And Geometric Structure Of Alnom And Alnom +, Albert R. Armstrong
Electronic And Geometric Structure Of Alnom And Alnom +, Albert R. Armstrong
Theses and Dissertations
Generally, the electronic stability of aluminum clusters is associated with either closed electronic shells of delocalized electrons, or aluminum in the +3 state. To explore alternative routes for electronic stability in aluminum oxide clusters, theoretical methods were used to examine the geometric and electronic structure of AlnOm (2≤n≤7; 1≤m≤10) clusters. Two types of electronically stable clusters with large HOMO-LUMO gaps were identified the first being Al2nO3m clusters with a +3 oxidation state on the aluminum, and the second being planar clusters such as Al4O4, Al5O3, Al …
Computational Studies On Mechanisms And Reactivity Of Mercury And Cobalt Organometallic Reactions, Jack Terrell Fuller
Computational Studies On Mechanisms And Reactivity Of Mercury And Cobalt Organometallic Reactions, Jack Terrell Fuller
Theses and Dissertations
Density Functional Theory (DFT) is a powerful tool for treating large organometallic structures efficiently and accurately. DFT calculations on the Hg-catalyzed oxidation of methane to methyl bisulfate in sulfuric acid suggest the lowest energy pathway involves a closed-shell electrophilic C–H activation mechanism coupled with metal alkyl reductive functionalization and oxidation by SO3. Comparison to Tl, Zn, and Cd suggests that Hg is unique in its ability to catalyze this set of reaction steps. Comparison to K2S2O8 highlights the selectivity of this C–H activation reaction as opposed to radical conditions. In contrast, DFT calculations indicate that CoIII(TFA)3 oxidizes methane through a …
Zinc Environment In Proteins: The Flexible And Reactive Core Of Hiv-1 Ncp7 And The Inhibitory Site Of Caspase-3, A. Gerard Daniel
Zinc Environment In Proteins: The Flexible And Reactive Core Of Hiv-1 Ncp7 And The Inhibitory Site Of Caspase-3, A. Gerard Daniel
Theses and Dissertations
Zinc is an essential cofactor of several proteins. The roles of zinc in these proteins are classified as catalytic, structural or regulatory. Zinc present in structural sites is considered to be a chemically inert, static structural element. On the contrary, previous studies on a C2H2 type zinc finger model compound and the C3H type HIV-1 NCp7 C-terminal zinc knuckle have shown that zinc at these sites can undergo coordination sphere expansion under the influence of a Pt based electrophile. The pentacoordination observed around zinc in these experiments raises an important question: are the structural zinc motifs found in the proteins …
Binding Energies And Solvation Of Organic Molecular Ions, Reactions Of Transition Metal Ions With, And Plasma Discharge Ionization Of Molecular Clusters, Isaac Kwame Attah
Binding Energies And Solvation Of Organic Molecular Ions, Reactions Of Transition Metal Ions With, And Plasma Discharge Ionization Of Molecular Clusters, Isaac Kwame Attah
Theses and Dissertations
In this dissertation, different approaches have been employed to address the quest of understanding the formation and growth mechanisms of carbon-containing molecular ions with relevance to astrochemistry. Ion mobility mass spectrometry and DFT computations were used to investigate how a second nitrogen in the pyrimidine ring will affect the formation of a covalent bond between the benzene radical cation and the neutral pyrimidine molecule, after it was shown that a stable covalent adduct can be formed between benzene radical cation and the neutral pyridine. Evidence for the formation of a more stable covalent adduct between the benzene radical cation and …
Implementation Of Optical Spectra Calculations In Fireball: A Local-Orbital Density Functional Theory Approach, Ivan Grigoryevich Okhrimenko
Implementation Of Optical Spectra Calculations In Fireball: A Local-Orbital Density Functional Theory Approach, Ivan Grigoryevich Okhrimenko
Theses and Dissertations
We have expanded the capabilities of the ab initio tight-binding molecular dynamics package FIREBALL to include calculations of optical properties. Basic zero order approximation is based on transitions between Kohn-Sham states. Corrections for electron-electron interactions are based on time dependant density functional theory (TDDFT). Consistent with the FIREBALL approach, we use precalculated integrals and approximations to make the program faster.