Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"gas-phase chemistry"”.
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Gas-Phase Covalent And Non-Covalent Ion/ion Chemistry Of Biological Macromolecules
<p>Gas-phase ion/ion chemistry involves the interaction of oppositely charged ions inside of the mass spectrometer. During this gas-phase chemistry, particle transfer (i.e., proton and electron) or synthesis can occur at rapid reaction rates. Particle transfer represents a mature area of ion/ion …
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Development and Evaluation of a Comprehensive Tropospheric Chemistry Model for Regional and Global Applications
… emissions must employ a tropospheric chemistry model that predicts realistic distributions of aerosols of all types. The need for a such a comprehensive yet computationally efficient tropospheric chemistry model is addressed in this research via systematic development of the various …
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Formation of ozone and growth of aerosols in young smoke plumes from biomass burning
… biomass is a major source of atmospheric trace gases and aerosols. Regional and global-scale models of atmospheric chemistry and climate take estimates for these emissions and arbitrarily "mix" them into grid boxes with horizontal scales of 10-200 km. This procedure ignores the complex …
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Modeling reactive rarefied flows in Chemical Vapor Infiltration using Direct Simulation Monte Carlo
… silicon carbide (SiC) matrix composites. Gas-phase precursors flow into a porous fiber, react, and deposit to form the ceramic matrix. Deposition quality and rate are strongly influenced by surface reactions, depending on temperature, gas flow, and reactor pressure. This study applies a …
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High Fidelity Chemistry And Radiation Modeling For Oxy-Combustion Scenarios
… in an oxy-combustion atmosphere, several refined gas-phase chemistry and radiative property models have been formulated for laminar to highly turbulent systems. This thesis examines the accuracies of several chemistry and radiative property models employed in computational fluid dynamic (CFD) …
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Exploring the contributions of liquid-phase sulfur chemistry to the mass-independent sulfur fractionation of the Archean rock record
… and despite a number of recent studies on the gas-phase chemistry of sulfur, no definite overall picture has emerged to date as to the precise origin and preservation of the Archean mass-independent sulfur signal. The interpretation of the Archean sulfur MIF as a strong constraint for …
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A study of the tropospheric oxidation of volatile organic compounds using chemical ionization mass spectrometry
… The ability to accurately model tropospheric chemistry depends on kinetic and mechanistic information for a wide variety of species. The gas-phase chemistry of the troposphere is dominated by the oxidation of trace species such as methane. One important intermediate in the oxidation of methane …
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Exploring the Chemistry of Methoxide with Oxygen through Photoelectron Imaging Spectroscopy
… imaging spectroscopy is employed to probe the gas-phase chemistry between methoxide (CH3O) and oxygen, including evidence of previously unexplored reaction paths and providing further insight into the fundamentals of chemical bonding. First, the known reaction of CH3O and O2 to produce the …
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Mass spectrometric characterization of peptide radical ions and implication for radical chemistry
<p>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 …
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Investigation into the Hydrothermal Treatment of Sugarcane Bagasse under Near- and Supercritical Conditions
… additives and their effects on a single product phase. This research examined the influence of temperature, residence time, biomass concentration, and particle size on volatiles production from the hydrothermal conversion of sugarcane bagasse. Temperature had the greatest impact on volatile …
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Detailed Population Balance Modelling of Titanium Dioxide Nanoparticle Synthesis
… obtained from a fully-coupled simulation with gas-phase chemistry, flow dynamics and a simple particle model. The new methodology addresses a previously unidentified issue in employing the post-processing step to simulate flames with steep temperature gradients. A corrective sample volume …
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Modeling The Evolution Of Vehicle Exhaust Plume Near Road And In Laboratory Dilution Systems Using The Ctag Model
… the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model. CTAG is designed to simulate the transport and transformation of multiple air pollutants in various environments. For near-road applications, CTAG couples the major turbulent mixing processes with gas-phase chemistry and …
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Design of a high pressure flow reactor for gas phase kinetics
… characterize chemical kinetics with respect to gas phase chemistry, specifically to increase the operating parameters in order to study fuels in engine like conditions (high temperatures, pressures, and fast residence times). This desire to study fuels at such extreme conditions stems from the …
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Morphology and polymorphism of TiO2 nanoparticles prepared in premixed stagnation flames
… closure (MoMIC) and is fully coupled with the gas-phase chemistry and flow models. The model predictions are compared against literature data which reveals a good agreement for particle size but some discrepancy in particle geometric standard deviation (GSD). This suggests that the particle …
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Coal gasification for fuel synthesis: Multiphysics modeling and new concepts
<p>Fuel synthesis through gasification of carbonaceous materials (e.g. coal and biomass) has the potential to provide a solution to the increasing demand for energy and liquid transportation fuels. To theoretically understand the complex physical and chemical processes in a gasifier and to identify …
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Idealized particle-resolved large-eddy simulations to evaluate the impact of emissions spatial heterogeneity on CCN activity
… concentration fields of primary aerosol and gas-phase species instead of spatially heterogeneous concentrations. Aerosol processes such as gas-particle partitioning and coagulation are concentration-dependent in a non-linear manner, and thus the representation of spatially heterogeneous …
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Investigation of condensed and early stage gas phase hypergolic reactions
… In order to achieve ignition, condensed phase fuel and oxidizer must undergo simultaneous physical mixing and chemical reaction. This process generates heat, intermediate condensed phase species, and gas phase species, which then may continue to react and generate more heat until ignition …
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The aging of organic aerosol in the atmosphere : chemical transformations by heterogeneous oxidation
… has left the general field of condensed-phase atmospheric organic chemistry relatively under-developed when compared with either gas-phase chemistry or the formation of inorganic compounds. In this work, we endeavor to improve the general understanding of the narrow class of oxidation …
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Improving the understanding of the influence of emissions of biogenic volatile organic compounds on climate.
… magnitude and sign. An important factor is the gas phase chemistry of BVOCs since this influences atmospheric oxidising capacity and thus radiative forcing from CH4, O3, aerosol and clouds. Recent advances in the understanding of BVOC oxidation chemistry, which reduce the oxidant depletion …
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Modelling the optical, kinetic, and thermodynamic properties of soot precursor molecules
… cross-linked PAHs. These studies help model the gas phase chemistry that leads to the formation of these different types of PAHs, and also help assess their relevance to the formation of soot. The optical band gaps (OBGs) of curved, cross-linked, and radical PAHs are computed using a DFT method …
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