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2007

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Articles 301 - 313 of 313

Full-Text Articles in Chemical Engineering

Sensors For The Detection Of Hazardous Emissions, Aidan O'Dwyer Jan 2007

Sensors For The Detection Of Hazardous Emissions, Aidan O'Dwyer

Conference papers

This contribution will detail recent developments in sensor technology for the detection of hazardous emissions. The accurate measurement of such emissions is necessary if they are to be controlled to the appropriate regulations.

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Electrodeposition Of Rare Earth-Transition Metal Alloy Thin Films And Nanostructures, Rohit Mishra Jan 2007

Electrodeposition Of Rare Earth-Transition Metal Alloy Thin Films And Nanostructures, Rohit Mishra

LSU Doctoral Dissertations

Rare earth-transition metal alloys are of interest in MEMS and magnetic storage industries because of their unique magnetic properties. However, the applications of these alloys have been limited to bulk and thin film architectures because of the limitations of the contemporary vapor deposition technique to fabricate high aspect ratio nanostructures. The objective of this study is to develop an electrochemical process to deposit rare earth-transition metal alloys thus making it possible to deposit high aspect ratio nanostructures such as nanowires and nanotubes, which helps to tune their properties for specific applications. Electrodeposition of rare earth-transition metal alloys was achieved from …

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Particle And Dredge-Scale Kinetic Studies Of Hydrophobic Organic Chemical Desorption From Sediment, Justin Edward Birdwell Jan 2007

Particle And Dredge-Scale Kinetic Studies Of Hydrophobic Organic Chemical Desorption From Sediment, Justin Edward Birdwell

LSU Doctoral Dissertations

The discharge of hydrophobic organic chemicals (HOCs) and other hazardous substances from anthropogenic sources to surface waters and the atmosphere has led to the widespread contamination of bottom sediments throughout the world. HOCs collect in sediments due to their affinity for organic matter and other sorbents present on and within their solid matrices. There is interest in the movement of HOCs from historically contaminated, resuspended sediments to surface waters due to the connection between chemical desorption and bioavailability. Quantitatively accurate predictions of contaminant concentrations in environmental media are needed for reliable risk assessment and to develop strategies for protection of …

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Measurement Of Metal Migration In Sediment Caps With X-Ray Fluorescene, Ming Yin Jan 2007

Measurement Of Metal Migration In Sediment Caps With X-Ray Fluorescene, Ming Yin

LSU Doctoral Dissertations

ABSTRACT Sand is often used as a passive barrier to slow release of metals from the sediment and to separate benthic organisms from the sediment. Materials that effectively adsorb metals have the potential to provide significantly greater effectiveness by further retarding metal release. In this thesis, the effectiveness of apatite and Phosphil®, which contain phosphate in a form that can absorb many metals, is evaluated with a series of sorption and migration column experiments using Cr, Cu, Zn and Pb. Langmuir shape isotherms were observed suggesting that the effectiveness of these materials decreases at high concentration. The sorption isotherm experiments …

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Mechanistic Modeling Of An Underbalanced Drilling Operation Utilizing Supercritical Carbon Dioxide, Faisal Abdullah Aladwani Jan 2007

Mechanistic Modeling Of An Underbalanced Drilling Operation Utilizing Supercritical Carbon Dioxide, Faisal Abdullah Aladwani

LSU Doctoral Dissertations

Mechanistic modeling of an underbalanced drilling operation using carbon dioxide has been developed in this research. The use of carbon dioxide in an underbalanced drilling operation eliminates some of the operational difficulties that arises with gaseous drilling fluids, such as generating enough torque to run a downhole motor. The unique properties of CO2, both inside the drill pipe and in the annulus are shown in terms of optimizing the drilling operation by achieving a low bottomhole pressure window. Typically CO2 becomes supercritical inside the drill pipe at this high density; it will generate enough torque to run …

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Experimental And Modeling Studies Of Contaminant Transport In Capped Sediments During Gas Bubble Ebullition, Qingzhong Yuan Jan 2007

Experimental And Modeling Studies Of Contaminant Transport In Capped Sediments During Gas Bubble Ebullition, Qingzhong Yuan

LSU Doctoral Dissertations

Fluxes of the three organics and eighteen metals from sediments were measured with diffusion chambers, and the effectiveness of a sand cap ascertained. The influence of sediment consolidation on contaminant flux and the mass transfer coefficient at the sediment-water interface was studied. A two-layer diffusion-advection model and consolidation model were coupled to elucidate the effect of sediment consolidation on chemical transport in the sediment-cap system. The model was tested and verified by the experimental data from microcosms, and then was used to predict phenanthrene flux under field conditions. The simulation results showed that consolidation could accelerate phenanthrene breakthrough and enhance …

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Cfd Simulation Of Contact Planarization, Shanti Vusirikala Jan 2007

Cfd Simulation Of Contact Planarization, Shanti Vusirikala

Masters Theses

"Semiconductor devices form the essential components of most electronic devices. The fabrication of circuit elements to manufacture these devices is done by a process known as photolithography, using photoresist layer deposition, optical masks, and etching. As feature sizes become smaller, higher optical precision is required, necessitating an optically flat surface on the photoresist layer. The surface of the photoresist layer can become uneven because of conformation to the topography of the layers underneath or a change in shape of the layer after evaporation of solvent. To combat this, Brewer Science, Inc. has developed a contact planarization process (CON-TACT®) in which …

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Enzymatic Synthesis And Characterization Of Oligopeptides, Co-Oligopeptides And Hydroxy Acid Capped Polypeptides In Mixed Aqueous Organic Media, Santhana Srinivasan Jan 2007

Enzymatic Synthesis And Characterization Of Oligopeptides, Co-Oligopeptides And Hydroxy Acid Capped Polypeptides In Mixed Aqueous Organic Media, Santhana Srinivasan

Doctoral Dissertations

"Proteolytic enzymes have been used for the synthesis of homo-oligomers and hydroxy acid capped peptides with amino acids and hydroxy acid esters as substrates in aqueous and aqueous organic biphasic and triphasic systems. However, successful incorporation of hydroxy acids in oligopeptide substrates has not been demonstrated. Use of monophasic media comprising of acetonitrile/water in which oligopeptide substrates were soluble was examined for the synthesis of oligomers of neutral and polar amino acids like Met, Tyr, Lys, Gly, Asp and Glu and tailored co-oligomers of Lys-Met and Arg-Met. Effect of reaction parameters such as starting substrate concentration, system composition, reaction time, …

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Heat And Mass Transport In Heat Pipe Wick Structures, Brian D. Iverson, Tyler W. Davis, Suresh V. Garimella, Mark T. North, Sukhvinder S. Kang Jan 2007

Heat And Mass Transport In Heat Pipe Wick Structures, Brian D. Iverson, Tyler W. Davis, Suresh V. Garimella, Mark T. North, Sukhvinder S. Kang

Faculty Publications

A novel experimental approach is developed for characterizing the performance of heat pipe wick structures. This approach simulates the actual operation of wick structures in a heat pipe. Open, partially submerged, sintered copper wicks of varying pore size are studied under the partially saturated conditions found in normal heat pipe operation. A vertical wick orientation, where the capillary lift is in opposition to gravity, is selected to test the wicks under the most demanding conditions. Mass transport measurements of the working fluid, in addition to the temperature field, are obtained for the porous wicks under the action of a discrete …

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Model Compound Study Of The Pathways For Aromatic Hydrocarbon Formation In Soot, Randall E. Winans, Nancy A. Tomczyk, Jerry E. Hunt, Mark S. Solum, Ronald J. Pugmire, Thomas H. Fletcher Jan 2007

Model Compound Study Of The Pathways For Aromatic Hydrocarbon Formation In Soot, Randall E. Winans, Nancy A. Tomczyk, Jerry E. Hunt, Mark S. Solum, Ronald J. Pugmire, Thomas H. Fletcher

Faculty Publications

As a follow-up of previous work on the flame pyrolysis of biphenyl and pyrene, a more detailed analysis of the pyrolytic products has been done using additional NMR data obtained on the whole soot sample correlated with detailed high-resolution and GC mass spectrometry data on the solvent-extracted portion of the same samples. These latter data complement the earlier NMR data with details of the pre-sooting structures, referred to as “young soot”, in pyrolyzed biphenyl samples collected at 1365, 1410, and 1470 K and pyrene at 1410 and 1470 K. The data reveal the roles played by free-radical-assisted polymerization reactions as …

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Effects Of Moisture On Ignition Behavior Of Moist California Chaparral And Utah Leaves, Thomas H. Fletcher, Brent M. Pickett, Steven G. Smith, Gregory S. Spittle, Megan M. Woodhouse, Elizabeth Haake, David R. Weise Jan 2007

Effects Of Moisture On Ignition Behavior Of Moist California Chaparral And Utah Leaves, Thomas H. Fletcher, Brent M. Pickett, Steven G. Smith, Gregory S. Spittle, Megan M. Woodhouse, Elizabeth Haake, David R. Weise

Faculty Publications

Individual cuttings from eight plant species native to California chaparral or Utah were burned in a well-controlled, well-instrumented facility. Gas temperatures above a flat-flame burner were controlled at 987 C and 10 mol% O2, resulting in a heat flux at the leaf surface varying from 80–140 kW/m2. High moisture leaves were observed to burst due to the rapid escape of vapor from the leaf interior. Bubbles in or on the leaf surface were observed for leaves with moderate moisture contents. A large number of leaf temperature measurements were made, along with measurements of the ignition time …

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Using Computational Fluid Dynamics Modeling To Improve The Performance Of A Solar Co2 Converter, Thomas H. Fletcher, Ralph J. Price, Reed J. Jensen Jan 2007

Using Computational Fluid Dynamics Modeling To Improve The Performance Of A Solar Co2 Converter, Thomas H. Fletcher, Ralph J. Price, Reed J. Jensen

Faculty Publications

A solar collector to convert CO2 to CO at high temperature was previously developed, achieving a product with 4-6 mol % CO from pure CO2. Modeling results showed that reactions occurred in the thermal boundary layer of the heated zirconia rod at temperatures greater than 2300 K. This paper describes results of computer modeling of advanced designs meant to increase the conversion of CO from CO2. Several design modifications were tested using the model, including changing the cool-down region configuration, increasing the zirconia rod diameter, and changing the zirconia rod shape. Several operational adjustments were also modeled, including reducing the …

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High-Pressure Turbine Deposition In Land-Based Gas Turbines From Various Synfuels, Thomas H. Fletcher Jan 2007

High-Pressure Turbine Deposition In Land-Based Gas Turbines From Various Synfuels, Thomas H. Fletcher

Faculty Publications

Ash deposits from four candidate power turbine synfuels were studied in an accelerated deposition test facility. The facility matches the gas temperature and velocity of modern first-stage high-pressure turbine vanes. A natural gas combustor was seeded with finely ground fuel ash particulate from four different fuels: straw, sawdust, coal, and petroleum coke. The entrained ash particles were accelerated to a combustor exit flow Mach number of 0.31 before impinging on a thermal barrier coating (TBC) target coupon at 1150°C. Postexposure analyses included surface topography, scanning electron microscopy, and x-ray spectroscopy. Due to significant differences in the chemical composition of the …

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