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Full-Text Articles in Engineering

Development Of A Regenerable Calcium-Based Sorbent For Hot Gas Cleanup , Tetteh Akiti Jan 2001

Development Of A Regenerable Calcium-Based Sorbent For Hot Gas Cleanup , Tetteh Akiti

Retrospective Theses and Dissertations

Experiments were conducted to develop a regenerable calcium-based sorbent for hot coal gas desulfurization. Spherical sorbent pellets were fabricated in a novel core-in-shell configuration. All pellets were prepared using a bench-scale pelletizer. In accordance with the core-in-shell concept, a reactive calcium compound (CaO) was surrounded by a strong shell consisting of a composite material. Limestone (CaCO3) and hemihydrate (CaSO4ยท0.5 H2O) were used as starting materials that were eventually decomposed to produce CaO. Different types of cements and aluminas were investigated as strength enhancing shell materials.;The sorbent pellets were characterized by measuring their compressive strength, surface area, pore ...


The Roles Of The Surface Oxide Film And Metal-Oxide Interfacial Defects In Corrosion Initiation On Aluminum , Huiquan Wu Jan 2001

The Roles Of The Surface Oxide Film And Metal-Oxide Interfacial Defects In Corrosion Initiation On Aluminum , Huiquan Wu

Retrospective Theses and Dissertations

In the first part, a mathematical model was developed for oxide thickness and faradaic current, assuming high-field conduction and a uniform oxide layer thickness, and incorporating as input the measured potential. Electrochemical current and potential transients were measured during anodic oxidation of aluminum. The ratio of the experimental faradaic current density to the predicted one using high field model, p, was calculated. The measured faradaic current is about 104 times smaller than that predicted by this model initially, but the two converge after the initial period of time when p approaches 1. This discrepancy may be caused by several reasons ...


Investigation Of The Peroxovanadate Sol-Gel Process And Characterization Of The Gels , Craig Joseph Fontenot Jan 2001

Investigation Of The Peroxovanadate Sol-Gel Process And Characterization Of The Gels , Craig Joseph Fontenot

Retrospective Theses and Dissertations

Vanadium oxide gels derived from aqueous solution of V2O 5 and H2O2 have been investigated using in situ 51V NMR and laser Raman spectroscopic techniques. On the basis of this characterization, a pathway for peroxovanadate decomposition has been proposed, including the presence of two peroxovanadate dieters. New Raman bands and assignments for these species are reported. Experimental 51V NMR evidence suggested the VO2+ species was directly involved in the formation of the gel. The vanadia xerogels were studied using 51V and 17O MAS NMR, 17 O 3QMAS NMR, TGA, DSC, XRD, SEM and laser Raman spectroscopy. Based primarily on the ...


Computational Fluid Dynamics For Design And Optimization Of Tubular Low-Density Polyethylene Reactors , Nitin Hiralalsa Kolhapure Jan 2001

Computational Fluid Dynamics For Design And Optimization Of Tubular Low-Density Polyethylene Reactors , Nitin Hiralalsa Kolhapure

Retrospective Theses and Dissertations

Polymer reactor models often assume that the reactants are mixed rapidly and thus the concentrations can be considered to be uniform at small scales. However, for fast reactions or for viscous systems, poor mixing of chemical species significantly affects the reactor performance while adversely affecting product quality. The purpose of this research is to formulate a generalized algorithm based on state-of-the-art computational fluid dynamics (CFD) techniques such as full or presumed probability density function (PDF) methods to better understand the role of micromixing in mixing-sensitive chemical processes. The impressive capabilities of the algorithm are investigated using an industrial test-case of ...


Surface And Solvent Influences On Protein Crystallization , Xiaojing Pan Jan 2001

Surface And Solvent Influences On Protein Crystallization , Xiaojing Pan

Retrospective Theses and Dissertations

The role of water in protein crystallization was explored by investigating the effects of three factors (salts, point mutations and pressure) on subtilisin crystallization.;Solubility and growth kinetics of three subtilisin mutants in three salt solutions were measured. The decrease of the solubility of Properase RTM and PurafectRTM subtilisin followed the reverse order of the Hofmeister series: SCN- > NO3- > Cl-. The solubility of ProperaseRTM was higher than other two mutants. Crystal morphology changed with the nature of salts and the substitution of surface residues. The required supersaturation (c-s)/s for a given growth rate increased when solubility was decreased. The ...


Study Of Transport And Dissolution Of A Nonaqueous Phase Liquid In Porous Media: Effects Of Low-Frequency Pulsations And Surfactants , Mirrya Mosier Fontenot Jan 2001

Study Of Transport And Dissolution Of A Nonaqueous Phase Liquid In Porous Media: Effects Of Low-Frequency Pulsations And Surfactants , Mirrya Mosier Fontenot

Retrospective Theses and Dissertations

The transport and dissolution of residual non aqueous phase liquids (NAPLs) trapped in water saturated porous media is a problem pertinent to both environmental and petrochemical industries. In this work we have quantitatively examined the complete dissolution of residual entrapped NAPL at the pore-scale in three dimensions using refractive index matching techniques along with planar laser induced fluorescence. The results yielded pore-scale information regarding ganglia volume, surface area, and position over time at various Capillary numbers. We found that with increasing Capillary numbers, the time for total dissolution decreased. In addition, it appears that large ganglia exhibit fractal area to ...


Pathway And Surface Mechanism Studies Of 1,3-Butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts , William David Schroeder Jan 2001

Pathway And Surface Mechanism Studies Of 1,3-Butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts , William David Schroeder

Retrospective Theses and Dissertations

The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9--14 m2/g, and compositions were within the solid solution regime, i.e. below 15.0 mol% MoO3/(MoO3 + V2O 5). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V+4 and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to malefic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The ...


Effects Of Fluid-Induced Shear Stress On Articular Cartilage Regeneration Under Simulated Aspects Of Microgravity , David James Wendt Jan 2001

Effects Of Fluid-Induced Shear Stress On Articular Cartilage Regeneration Under Simulated Aspects Of Microgravity , David James Wendt

Retrospective Theses and Dissertations

Because a true microgravity environment results in a reduction of mechanical forces on the human body, possibly at each level of physiological organization, we have investigated the effects of applying a stimulus in the form of fluid-induced shear stress to regenerating articular cartilage cultured in an environment hypothesized to simulate aspects of microgravity. Significant alterations to the NASA-designed rotating wall vessel were made to create a unique bioreactor specifically designed for this study. This distinctive reactor not only allowed us to apply fluid-induced shear stress to tissue constructs, it allowed for control of its magnitude, and for independent control of ...