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Full-Text Articles in Physical Sciences and Mathematics
Mass Spectrometric Characterization Of Peptide Radical Ions And Implication For Radical Chemistry, Lei Tan
Mass Spectrometric Characterization Of Peptide Radical Ions And Implication For Radical Chemistry, Lei Tan
Open Access Dissertations
Gas-phase radical ion chemistry has attracted increasing research interest from the mass spectrometry (MS) society because it provides new capabilities in bio-analysis which often complements traditional MS methods developed from even-electron ions. Fundamental studies of biomolecule related radical species are essential to broadening the scope of radical chemistry and pushing the frontiers of its analytical applications. This dissertation mainly discusses the gas-phase chemistry of peptide sulfinyl radicals (-SO·), which has been rarely studied before. In order to establish an effective research approach, a method that can generate site-specific peptide sulfinyl radical ion has been developed. This method is based on …
Studies Of Arctic Halogen Chemistry From The Snowpack To The Gas Phase, Kyle D Custard
Studies Of Arctic Halogen Chemistry From The Snowpack To The Gas Phase, Kyle D Custard
Open Access Dissertations
The temporary depletion of both tropospheric ozone and gaseous mercury during the Arctic springtime has been a focus of active research over the past several decades. Both of these phenomena have been linked to chemical reactions with halogen radicals. In particular, bromine atoms have been shown to act as the primary driver for these chemical depletions, although both chlorine and iodine atoms also contribute. Molecular bromine, along with its oxidation products, have been well studied in the Arctic, yet chlorine has not. Chlorine is known to impact the local oxidation capacity via its high reactivity with volatile organic compounds. Despite …
Polarization-Dependent Nonlinear Optical Microscopy Methods For The Analysis Of Crystals And Biological Tissues, Emma L. Kerian
Polarization-Dependent Nonlinear Optical Microscopy Methods For The Analysis Of Crystals And Biological Tissues, Emma L. Kerian
Open Access Dissertations
The ability to solve a high-resolution protein structure is largely dependent on the successful generation and identification of protein crystals prior to X-ray diffraction (XRD). For novel protein targets, high-throughput crystallography often involves generation of multiple targets and thousands of crystallization trials per target to generate diffraction-quality crystals. Second harmonic generation (SHG) imaging has been developed as a fast, non-destructive and sensitive method for the selective identification of protein crystals, even in highly scattering environments. Polarization-dependent SHG microscopy methods were developed to assess the presence of multidomain crystals to provide a handle on crystal quality. In addition, polarization-dependent two-photon excited …
A Bracketing Method For Proton Affinity Measurements Of Dehydro-And Didehydropyridines, Guannan Li
A Bracketing Method For Proton Affinity Measurements Of Dehydro-And Didehydropyridines, Guannan Li
Open Access Theses
Proton affinity (PA) is a fundamental property that is related to the structure and reactivity of a molecule. Currently, very few experimental PA values are available for organic radicals and none for biradicals. Equilibrium methods cannot be used for these measurements. The traditional bracketing method is based on monitoring reactions of different reference bases with known proton affinities with the protonated analyte for the occurrence of exothermic proton transfer to determine the upper and lower limits of proton affinity. However, the energy deposited into the precursor ions upon CAD when forming protonated radicals may cause endothermic proton transfer reactions occur …
Development Of Experimental And Instrumental Systems To Study Biological Systems, Amanda J Hemphill
Development Of Experimental And Instrumental Systems To Study Biological Systems, Amanda J Hemphill
Open Access Dissertations
Chapters 1-4 of this thesis describes the development of an experimental system to measure diffusion-limited reaction kinetics in a biological environment. About 100 years ago, the relationship between reaction rate and diffusion in homogenous solution, ie water or buffer, was described as a linear relationship by Smoluchowski. Applying this theory naively would suggest that since the diffusion coefficients drop by factors of 4-100 then the rates of reaction would drop by the same amount. However, recent theory and simulations suggest that this does not hold. Even though biological diffusion coefficients drop to 0.1-20% of that in buffer, these recent studies …
Molecular Diagnosis Of Cancer Using Ambient Ionization Mass Spectrometry, Kevin S Kerian
Molecular Diagnosis Of Cancer Using Ambient Ionization Mass Spectrometry, Kevin S Kerian
Open Access Dissertations
My dissertation focuses on advancing the development and application of ambient ionization mass spectrometry methodology and technology to the biomedical field. The primary ambient ionization method used in my studies is desorption electrospray ionization mass spectrometry (DESI-MS) imaging, which has been previously used to analyze and differentiate disease state (i.e. tumor and normal) and in some cases tumor subtype of human liver, kidney, bladder, testicular, prostate, and brain cancers. DESI-MS imaging is an ideal method for disease diagnosis, because it can be used to directly correlate disease state with histopathology to develop and validate MS libraries built using the molecular …
Laboratory Studies On The Production Of Alpha-Pinene-Derived Organic Nitrates And Their Atmospheric Fate, Joel David Rindelaub
Laboratory Studies On The Production Of Alpha-Pinene-Derived Organic Nitrates And Their Atmospheric Fate, Joel David Rindelaub
Open Access Dissertations
Currently, the formation yields of organic nitrates from the oxidation of biogenic volatile organic compounds, such as α-pinene, is highly uncertain, negatively impacting our knowledge on tropospheric ozone production and the fate of atmospheric NOx. To lower this uncertainty, we quantified the organic nitrate yield from the OH radical oxidation of α-pinene under high NOx conditions. The α-pinene- derived nitrates created in chamber experiments readily partitioned to the aerosol phase and underwent particle phase hydrolysis, indicating that these processes are likely a sink for atmospheric NOx. The hydrolysis of organic nitrates was found to be …
Structure-Activity Relationships For The Water-Gas Shift Reaction Over Supported Metal Catalysts, Kaiwalya D. Sabnis
Structure-Activity Relationships For The Water-Gas Shift Reaction Over Supported Metal Catalysts, Kaiwalya D. Sabnis
Open Access Dissertations
The Water-Gas Shift (WGS) reaction (CO + H2O → CO2 + H2) is an important chemical process for industrial hydrogen production. The overall goal of this project is to use kinetic experiments and in situ characterization techniques in tandem, in order to derive structure-activity relationships for various catalytic systems. These relationships facilitate the rational catalyst design by identification of catalyst descriptors. In order to establish such relationships, various studies were undertaken, such as (i) effect of transition admetals on the WGS catalysis by molybdenum carbide (ii) effect of residual oxygen content on the performance of …