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Articles 1 - 16 of 16
Full-Text Articles in Physical Chemistry
Probing Charge Transport Mechanisms In 2d Semiconductive Metal Organic Framewoks, James Nyakuchena
Probing Charge Transport Mechanisms In 2d Semiconductive Metal Organic Framewoks, James Nyakuchena
Dissertations (1934 -)
Metal organic frameworks (MOFs) are a class of highly porous crystalline materials constructed from metal nodes connected by multitopic organic ligands. Due to their unique properties such as large surface area, tunable pore structure, and structural diversity, they have demonstrated potential in a wide array of applications including gas storage and separation, sensing, catalysis, and drug delivery. However, there are only a handful of MOFs reported that have electrical conductivity, which prevents their applications in photoelectronic and photocatalytic applications. This is because hard metals and redox inactive ligands with terminal hard linking bases such as carboxylates are often used in …
Metal Organic Frameworks (Mofs) Supported Single Atom Catalysts (Sacs) For Solar Fuel Conversion, Humphrey Chiromo
Metal Organic Frameworks (Mofs) Supported Single Atom Catalysts (Sacs) For Solar Fuel Conversion, Humphrey Chiromo
Dissertations (1934 -)
The continual reliance on non-renewable energy sources from fossil fuels to meet the world’s energy demand is causing serious environmental problems such as air pollution and global warming, hence there is a need of an alternative clean sustainable energy source. Exploration of clean sustainable renewable energies shows great promise to replace fossil fuels to meet global energy needs. Among the renewable energy sources, solar energy represents one of the most promising alternative energy sources due to its abundance and sustainability. However, the major challenge is the harvesting and storage of solar energy. One of the promising approaches to resolve these …
The Photodynamic And Structural Analyses Of Advanced Materials For Solar Fuel Conversion, Brian Pattengale
The Photodynamic And Structural Analyses Of Advanced Materials For Solar Fuel Conversion, Brian Pattengale
Dissertations (1934 -)
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 the …
Nucleotide-Dependent Preferential Localization Of Ras In Model Membranes With Lipid Raft Nanodomains, Anna Shishina
Nucleotide-Dependent Preferential Localization Of Ras In Model Membranes With Lipid Raft Nanodomains, Anna Shishina
Dissertations (1934 -)
Membrane proteins constitute a third of all proteins in the cell and more than 50% of drug targets. However, the analysis of membrane proteins has many challenges owing to their partially hydrophobic surfaces, flexibility and lack of stability. One example of an essential membrane protein is Ras superfamily. Ras is a small monomeric GTPase involved in regulation of cell growth, proliferation and differentiation. Therefore, Ras and its effectors are among the most important targets for cancer therapy. A detailed knowledge of the processes occurring during signal propagation via Ras might help to elucidate the mechanisms of the involved signal cascades. …
Mixed Quantum/Classical Theory (Mqct) For Rotationally And Vibrationally Inelastic Scattering And Its Application To The Molecules Of Astrochemical Importance, Alexander Semenov
Mixed Quantum/Classical Theory (Mqct) For Rotationally And Vibrationally Inelastic Scattering And Its Application To The Molecules Of Astrochemical Importance, Alexander Semenov
Dissertations (1934 -)
This thesis presents developments and applications of the mixed quantum/classical theory (MQCT) for inelastic scattering. In this approach, translational motion of collision partners is treated classically, while the internal degrees of freedom – rotational and/or vibrational motion – are treated quantum mechanically. Within this framework calculations of rotationally inelastic cross sections are carried out in a broad range of collision energies and results are compared against the exact full quantum data for several real systems. For CO +He, N2 + Na and H2 + He the agreement is excellent through six orders of magnitude range of cross sections values and …
Functional And Structural Studies Of Cytochromes P450 By Resonance Raman Spectroscopy, Yilin Liu
Functional And Structural Studies Of Cytochromes P450 By Resonance Raman Spectroscopy, Yilin Liu
Dissertations (1934 -)
Cytochrome P450 is a broad class of heme monooxygenase enzymes which catalyze various oxidative transformations. There are two main kinds of mammalian P450s: steroidogenic and drug metabolizing P450s. The first project involves a steroidogenic P450, CYP17A1, occupying a central role in the biosynthesis of steroid hormones. It catalyzes hydroxylation reaction on pregnenolone and progesterone, generating 17OH-pregnenolone and 17OH-progesterone, presumably utilizing a “Compound I” species. However, these hydroxylated products can be further processed in a second oxidative cycle to cleave the C17–C20 bond to form dehydroepiandrosterone or androstenedione, respectively, a crucial step in androgen production. Interestingly, it is well known that …
On The Structure And Properties Of S-Nitrosated Cysteine Models: A Computational Study, Dmitry Khomyakov
On The Structure And Properties Of S-Nitrosated Cysteine Models: A Computational Study, Dmitry Khomyakov
Dissertations (1934 -)
S-Nitrosation of cysteine (Cys) residues, a covalent modification of its S atom by NO group, is a major post-translational modification of proteins. Despite the importance of S-nitrosoproteins in numerous physiological processes, lability of the S-nitrosothiol (-SNO) group hinders the research progress. In this work, computational chemistry methods were applied to S-nitrosated cysteine (CysNO) models to gain a deeper insight into its structure and properties. First, we obtained the most accurate at the moment computational estimation of the molecular structure and properties of CH3SNO model molecule using Feller-Peterson-Dixon (FPD) ab initio protocol. The S–N bond length in cis- CH3SNO is calculated …
Theoretical Study Of Ozone Forming Recombination Reaction And Anomalous Isotope Effect Associated With It, Alexander Teplukhin
Theoretical Study Of Ozone Forming Recombination Reaction And Anomalous Isotope Effect Associated With It, Alexander Teplukhin
Dissertations (1934 -)
The ozone forming recombination reaction stands out among many chemical processes that take place in the atmosphere. This reaction is responsible for the reconstruction of ozone layer, which protects life on Earth from harmful ultra-violate radiation and is a source of so-called anomalous isotope effect in ozone. The reaction was intensively studied, but at a very basic level. There were only couple of papers where the recombination rate coefficient was computed and found to roughly agree with the experimental data. In this dissertation, the recombination process in ozone is approached using new and efficient method, which includes several modern techniques. …
Computational Modeling Of S-Thiolation Reaction: Toward Discovering The Enzymatic Mechanisms Of Endogenous Hno Formation, Elena Ivanova
Computational Modeling Of S-Thiolation Reaction: Toward Discovering The Enzymatic Mechanisms Of Endogenous Hno Formation, Elena Ivanova
Dissertations (1934 -)
S-nitrosothiols (RSNOs) have long been proposed as potential sources of the elusive endogenous nitroxyl (HNO) via S-thiolation reaction with thiols. It is however not clear how S-thiolation can compete with the trans-S-nitrosation pathway commonly observed in vitro. Based on the insights into the highly unusual, antagonistic chemical nature of RSNO molecules, we hypothesize that, while difficult in vitro, S-thiolation could easily lend itself to enzymatic catalysis. To explore this possibility, we adopted a bottom-up computational approach that aims to identify possible catalytic mechanisms able to steer the RSNO + thiol reaction toward HNO production. Inspired by recent discovery of small …
An Investigation Of The Requirements For Excimer Formation And Charge Stabilization In Model Pi-Stacked Assemblies, Brandon Uhler
An Investigation Of The Requirements For Excimer Formation And Charge Stabilization In Model Pi-Stacked Assemblies, Brandon Uhler
Dissertations (1934 -)
Formation of -stacked excimers plays an important role in many systems, ranging from biological phenomena and polymer formation and function to photovoltaic devices and organic molecular electronics. In these systems, the geometrical reorganization of the ground state upon photoexcitation is still a subject of debate. In this work, we compare the dynamics of excimer formation and hole (charge) stabilization in fluorene and fluorene-based model systems. We use a variety of gas-phase methods to examine the spectroscopy and dynamics of these systems, including Two-Color Resonant Two-Photon Ionization (2CR2PI), Hole-Burning (HB), Laser Induced Fluorescence (LIF), and Dispersed Fluorescence (DF). In order to …
Resonance Raman Studies Of Oxygenated Forms Of Myoglobin And Cyp2b4 And Their Mutants, Ying Wang
Resonance Raman Studies Of Oxygenated Forms Of Myoglobin And Cyp2b4 And Their Mutants, Ying Wang
Dissertations (1934 -)
Important oxidative heme enzymes use hydrogen peroxide or activate molecular oxygen to generate highly reactive peroxo-, hydroperoxo- and feryl intermediates resulting from heterolytic O-O bond cleavage. Members of the cytochrome P450 superfamily catalyze difficult chemical transformations, including hydroxylations and C-C bond cleavage reactions. In mammals, these enzymes function to reliably produce important steroids with the required high degree of structural precision. On the other hand, certain other mammalian P450s serve a different role, efficiently metabolizing xenobiotics, including pharmaceuticals and environmental pollutants. Though so important, the precise mechanisms involved in such transformations are incompletely understood, because of difficulties in structurally characterizing …
Novel Numerical Models Of Electrostatic Interactions And Their Application To S-Nitrosothiol Simulations, Maxim Vadimovich Ivanov
Novel Numerical Models Of Electrostatic Interactions And Their Application To S-Nitrosothiol Simulations, Maxim Vadimovich Ivanov
Dissertations (1934 -)
Atom-centered point charge model of the molecular electrostatics remains a major workhorse in the atomistic biomolecular simulations. However, this approximation fails to reproduce anisotropic features of the molecular electrostatic potential (MEP), and the existing methods of the charge derivation are often associated with the numerical instabilities. This work provides an in-depth analysis of these limitations and offers a novel approach to describe electrostatic interactions that paves the way toward efficient next-generation force fields. By analyzing the charge fitting problem from first principles, as an example of the mathematical inverse problem, we show that the numerical instabilities of the charge-fitting problem …
Mixed Valent Metal Pincer Complexes And Reactivity Of Metal Complexes Of Extended Pincer Ligands, Jeewantha Sampath Hewage
Mixed Valent Metal Pincer Complexes And Reactivity Of Metal Complexes Of Extended Pincer Ligands, Jeewantha Sampath Hewage
Dissertations (1934 -)
Historically, the study of mixed valence complexes has been critical for advancing our understanding of electron transfer processes in biological and abiological systems. The recent use of mixed valence complexes in electrochromic materials, and the promise of their use in future technological or molecular electronic applications, has spurred further interest in this class of compound. Previous studies by our research group have shown that gallium(III) or tricarbonylrhenium(I) complexes of pincer-type ligands with diarylamido anchors and either pyrazol-1-yl (pz) or diarylphosphino (PAr2) flanking donors are electroactive species with quasi reversible ligand-centered oxidations. Moreover, the one-electron oxidized derivative with pz flankers, [Ga(L)(L+)]2+ …
S-Nitrosothiols: Electronic Structure And Substituent Effects, Matthew Flister
S-Nitrosothiols: Electronic Structure And Substituent Effects, Matthew Flister
Dissertations (1934 -)
S-nitrosothiols (RSNOs) are biologically important molecules involved in the storage and transport of nitric oxide (NO) and account for much of its signaling activity in living organisms. RSNOs have significant impact on NO signaling through, S-nitrosation, a major post-translational modification of proteins. These unstable thiol derivatives readily undergo homolytic dissociation of the S–N bond to release NO. RSNOs have potential therapeutic applications as NO donors, although the development of novel RSNOs has been slow due to the complex electronic structure of the –SNO group. A specific focus on the impact of the –R group on RSNO properties via substituent effect …
With Vibrationally Excited Thiophosgene Molecule And Double-Well Ion Traps, Dmytro Shyshlov
With Vibrationally Excited Thiophosgene Molecule And Double-Well Ion Traps, Dmytro Shyshlov
Dissertations (1934 -)
For practical realization of quantum information processing we need a quantum system that provides reliable preparation of the initial state, high-fidelity quantum gate operations, error tolerance, readout of the result of quantum computation and scalability of the system to increase the number of qubits. In this dissertation we show how these requirements can be addressed for molecular quantum computer. For computational study of quantum information processing with molecules we employ thiophosgene (SCCl2) molecule that has been used as a test system for quantum control experiments [Mol. Phys. 105, 1999 (2007)]. We investigate the gateway scheme of control in which transitions …
Resonant Two-Photon Ionization Studies Of Non Covalent Interactions In Halo Aromatic Clusters And Spin-Orbit Coupling Modeling In Mono-Halocarbenes, Silver Nyambo
Dissertations (1934 -)
Non-covalent interactions in halobenzenes (PhX) (X=F, Cl, Br) and phenylamine (C6 H5 NH2 ) have been studied here using resonance two-photon ionization (R2PI) spectroscopy combined with a linear TOF-mass spectrometer. Their interaction with polar molecules in form of ammonia (NH 3 ) and trifluorohalomethanes (CF3 X) has also been studied. DFT and TD-DFT calculations using M06-2X functionals were carried out on different cluster conformations to compliment experimental results. A general trend of broadness in homogenous dimers (PhX)2 , has been attributed to mainly the presence of multiple cluster isomers and Frank-Condon activity in the low …