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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Computational Quantum Chemistry Studies Of The Interactions Of Amino Acids Side Chains With The Guanine Radical Cation., Edward Acheampong
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 …
Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman
Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman
Electronic Theses and Dissertations
Aggregation of polyglutamine (polyQ)-rich polypeptides in neurons is a marker for nine neurodegenerative diseases. The molecular process responsible for the formation of polyQ fibrils is not well understood and represents a growing area of study. To enable development of treatments that could interfere with aggregation of polyQ peptides, it is crucial to understand the molecular mechanisms by which polyQ peptides aggregate into fibrils. Many experimental techniques have been employed to probe polyQ aggregation, however, observations from these studies have not lead to a unified understanding of the properties of these systems, instead yielding competing, fragmented theories of polyQ aggregation. This …
Mechanistic Studies Of Reducible Metal Oxides As Hydrodeoxygenation Catalysts, Akbar Mahdavi Shakib
Mechanistic Studies Of Reducible Metal Oxides As Hydrodeoxygenation Catalysts, Akbar Mahdavi Shakib
Electronic Theses and Dissertations
Hydrodeoxygenation of phenol to benzene using ruthenium supported titania catalysts strongly varies depending on the support crystal structure and preparation conditions. Here, we performed spectroscopic characterization of titania supports to identify the surface impurities common to commercial and synthesized titania samples using a variety of spectroscopic methods. Sulfate impurities were detected for the commercial anatase samples and a procedure for their elimination was proposed so that inactive catalysts gained reactivity. Surface hydroxyls of different TiO2 samples (anatase, rutile, and pyrogenic) were identified using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments performed on vigorously cleaned surfaces and a facet-specific assignment …
Novel Relative Spontaneous Ignition Temperature Determination Using Carbon Dioxide Onset With Sta/Ir, Antonio David Trevino
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 seasons, the values for Chinese tallow stem, Chinese privet, and …
Steric Effects Of Alkyl Ammonium Salts On The Combustion Of Exchanged Smectite Clays, Celeste A. Keith
Steric Effects Of Alkyl Ammonium Salts On The Combustion Of Exchanged Smectite Clays, Celeste A. Keith
Electronic Theses and Dissertations
Bomb calorimetry was explored as a new method for determining the cation exchange capacity (CEC) of clays. Smectite clays were modified with several alkyl ammonium salts varying in number of carbons and the spatial orientation of the carbons about the central nitrogen atom. The clays used, standards purchased from the Source Clay Repository, have CECs of 44, 80, 88, and 120 meq/100 g. Theoretically, the combustion energy of the organo-clays should be approximately the same for each salt. Any differences in energy would be due to the different structures of the salts and how they are oriented in the interlamellar …
Surface Reaction And Diffusion Kinetics In Semiconducting Metal Oxide Film Gas Sensors, Aravind Reghu
Surface Reaction And Diffusion Kinetics In Semiconducting Metal Oxide Film Gas Sensors, Aravind Reghu
Electronic Theses and Dissertations
Chemiresistive metal oxide gas sensors based on materials such as SnO2, ZnO, and TiO2, have been investigated extensively by many researchers for a wide range of applications. The band bending model, based on the surface chemistry of highly reactive ionosorbed species (O2- or O-) and the semiconducting material properties of SnO2, TiO2 and ZnO, adequately predicts the dependence of the change in sensor conductivity (Δσ) as a function of target gas pressure and temperature. However, the band bending model is not applicable to gas sensors based on reducible oxides …
Computational Modeling Of Electronically Excited States In Cobalamin-Dependent Reactions., Brady D. Garabato
Computational Modeling Of Electronically Excited States In Cobalamin-Dependent Reactions., Brady D. Garabato
Electronic Theses and Dissertations
The current understanding of the photolytic properties of Vitamin B12 derivatives or cobalamins are summarized from a computational point of view. The focus is on two non-alkylcobalamins, cyanocobalamin (CNCbl) and hydroxocobalamin (HOCbl), two alkylcobalamins, methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), as well as the stable cob(II)alamin radical. Photolysis of alkylcobalamins involves low-lying singlet excited states where photo-dissociation of the Co-C bond forms singlet-born alkyl/cob(II)alamin radical pairs (RPs). Potential energy surfaces (PESs) of low-lying excited states as functions of both axial bonds provide the most reliable tool for analysis of photochemical and photophysical properties. Due to the size limitations associated with the …