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Chemical engineering

Materials Science and Engineering

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Full-Text Articles in Engineering

Synthesis And Characterization Of Nanostructured Aluminas , Weihua Deng Jan 2005

Synthesis And Characterization Of Nanostructured Aluminas , Weihua Deng

Retrospective Theses and Dissertations

In the work, mesoporous aluminas were produced by nonionic supramolecular templating and characterized to determine the stability of their physical structure during extended calcination at elevated temperatures. The effect of synthesis temperature on the physical structure of these materials and the resulting thermal evolution from synthesized aluminum hydroxide to transitional alumina was studied using thermogravimetric analysis. A high resolution multiple quantum magic angle spinning NMR spectroscopy method was used to determine quantitatively the evolution of the aluminum coordination during the thermal processing. The mesoporous alumina exhibited high stability upon prolonged heating, which is essential for their future applications in catalytic ...


Theoretical And Experimental Explorations In Atomic Force Microscopy , Anil Gannepalli Jan 2004

Theoretical And Experimental Explorations In Atomic Force Microscopy , Anil Gannepalli

Retrospective Theses and Dissertations

Nanotechnology is the capability to build by controlling the arrangement of individual atoms and molecules. Such a technology would be founded on the ability to control, manipulate and investigate matter at the atomic scale. The invention of atomic force microscope (AFM) and the advances in micro-cantilever based scanning probe technology have significantly enhanced the experimental capability to probe and modify matter at the nanoscale. However, it is still severely limited in achieving the necessary bandwidth, sensitivity and resolution. To further the advances in this field an in-depth understanding of the nature and effects of the tip-sample interactions is imperative. A ...


Analysis And Design Of A Calcium-Based Sulfur Sorbent For Applications In Integrated Gasification Combined Cycle Energy Systems , David Johann Ludwig Hasler Jan 2003

Analysis And Design Of A Calcium-Based Sulfur Sorbent For Applications In Integrated Gasification Combined Cycle Energy Systems , David Johann Ludwig Hasler

Retrospective Theses and Dissertations

The reactivity of various Ca-based sorbent materials in pelletized form with H2S or CO2 was investigated at high temperatures (750--880°C). An extensive study was conducted to compare the performance of sorbent pellets derived from plaster of Paris and limestone. Multicycle absorption and regeneration tests showed that plaster-based pellets out performed the limestone-based pellets primarily due to a higher surface area and mesoporosity.;The effect of pore-modifiers on the reactivity of limestone with H 2S was investigated by incorporating additives such as cornstarch, graphite and polyvinylalcohol (PVA) in the sorbent. Multicycle sulfidation and regeneration tests of the modified sorbent showed ...


Behavior Of Interfacial Micro-Defects In Aluminum And Its Oxide Film , Renchun Huang Jan 2003

Behavior Of Interfacial Micro-Defects In Aluminum And Its Oxide Film , Renchun Huang

Retrospective Theses and Dissertations

In this dissertation, numerical simulation was used to calculate the equilibrium solution composition of cylindrical nanopores in surface oxide films as a step to evaluate their possible roles in the breakdown of protective oxide films. The solution composition of such nanopores is of interest from a corrosion perspective, since they play prominent roles in several mechanisms for the breakdown of passive films leading to pitting corrosion. The chemical composition of the pore solution would determine whether rapid dissolution at the pore could initiate. The effects of nanoscale pore dimensions, solution pH and adsorbing ion borate concentration on the solution composition ...


Development Of Novel Polymeric Materials For Gene Therapy And Ph-Sensitive Drug Delivery: Modeling, Synthesis, Characterization, And Analysis , Brian Curtis Anderson Jan 2002

Development Of Novel Polymeric Materials For Gene Therapy And Ph-Sensitive Drug Delivery: Modeling, Synthesis, Characterization, And Analysis , Brian Curtis Anderson

Retrospective Theses and Dissertations

The aim of this work was to obtain a fundamental understanding of drug release mechanisms from polymers that undergo thermoreversible gelation and to synthesize new polymers based on these that exhibit both pH and temperature sensitivity. Novel block and random copolymers with cationic character have been developed for drug delivery and gene therapy applications. The development of these materials began with a study of the mechanism of drug release from poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) block copolymers. This study revealed the release rates of drugs from water-soluble hydrogels composed of the PEO-PPO-PEO block copolymer PluronicRTM F127 ...


Mechanistic Understanding Of Miscibility Effects On Fracture Strength Of Polymer Interfaces , Russell E. Gorga Jan 2002

Mechanistic Understanding Of Miscibility Effects On Fracture Strength Of Polymer Interfaces , Russell E. Gorga

Retrospective Theses and Dissertations

This research has provided a fundamental framework based on both experiment and theory to understand the fracture behavior as a function of system miscibility for nonreinforced polymer interfaces. The system chosen for study was polystyrene (PS) and the statistically random copolymer poly (styrene-r-4-bromostyrene) (PBS), where the volume fraction of bromine in the copolymer, f, and the degree of polymerization, N, control the miscibility. The phase behavior of thin film blends of PS and PBS as a function of f and N was studied using atomic force microscopy (AFM) and small angle X-ray scattering (SAXS). Simulations based on the Flory-Huggins theory ...


A Study Of Rheology, Processing And Phase Behavior Of Engineered Inorganic Glass-Organic Polymer Hybrid Materials , Peter Christopher Guschl Jan 2002

A Study Of Rheology, Processing And Phase Behavior Of Engineered Inorganic Glass-Organic Polymer Hybrid Materials , Peter Christopher Guschl

Retrospective Theses and Dissertations

Due to the consequence of expensive development costs that arise with manufacturing and synthesizing new polymers, interest in polymer blends has gained considerable attention in recent years. It is well known that the production of miscible and immiscible blends of polymers can lead to composite materials with special chemical, thermal, mechanical, and rheological properties. The morphology of immiscible polymer blends arises during mixing and is affected by the processing conditions, particular interactions, and the interfacial tension and viscosity ratio between the components. The significance of the interfacial energy between the blend components and its inherent effect on the rheology is ...


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 ...


Characterizing Growth Rates And Growth Rate Dispersion Of Secondary Nuclei As A Function Of Supersaturation , Christopher Michael Jones Jan 1999

Characterizing Growth Rates And Growth Rate Dispersion Of Secondary Nuclei As A Function Of Supersaturation , Christopher Michael Jones

Retrospective Theses and Dissertations

The growth rates of secondary crystal nuclei determine the number of crystals that will reach a size large enough to contribute to the final product mass in a crystallization process. Contact nuclei were chosen for study because crystals nucleated under conditions of low supersaturation are formed by contact or secondary nucleation. High supersaturation levels are required for primary nucleation to occur. Growth rate dispersion complicates the prediction of growth rates and product size distributions. Having growth rate dispersion in a crystallizing system means that despite the population of crystals having all been nucleated and grown under identical conditions, they grow ...


High Pressure Crystallization Of Purafect® Subtilisin , Ruta Yeshwant Waghmare Jan 1999

High Pressure Crystallization Of Purafect® Subtilisin , Ruta Yeshwant Waghmare

Retrospective Theses and Dissertations

The aim of this work was to study the effect of high pressure on kinetics of subtilisin crystallization and to use high pressure as a means to better understand the mechanism of crystallization;It is known that the effect of hydrostatic pressure on conformation varies with the protein being studied. To determine the effect of high pressure on the conformation of subtilisin, activity assays were used in addition to FTIR spectroscopy. Pressures up to 100 MPa were found to cause no irreversible conformational changes in subtilisin;To study the effect of high pressure on subtilisin crystallization, a factorial experiment was ...


Organometallic Chemical Vapor Deposition Of Copper Oxide Thin Films , Yu-Neng Chang Jan 1992

Organometallic Chemical Vapor Deposition Of Copper Oxide Thin Films , Yu-Neng Chang

Retrospective Theses and Dissertations

Copper oxide thin films were prepared by organometallic chemical vapor deposition (OMCVD or MOCVD) technique. This MOCVD process uses copper acetylacetonate (Cu(acac)[subscript]2) as the copper precursor. Spectroscopic (X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and infrared spectroscopy (IR)) and diffraction (X-ray diffraction (XRD)) methods were employed to analyze the chemical composition and oxidation state of copper in these films. According to spectroscopic results, the composition of these MOCVD film primarily depends on the deposition temperature and partial pressures of the reactants. As indicated by XPS and XRD results, Cu[subscript]2O films were prepared at 360 ...


Capillary-Reservoir Diffusion Studies In Hg-In Alloys Utilizing Continuous Resistivity Measurement Of Composition , Robert Hamilton Kaiser Jan 1971

Capillary-Reservoir Diffusion Studies In Hg-In Alloys Utilizing Continuous Resistivity Measurement Of Composition , Robert Hamilton Kaiser

Retrospective Theses and Dissertations

No abstract provided.


A Loop For Circulating Liquid Lead-Bismuth Mixtures: Corrosion Studies And Operation , John Charles Clifford Jan 1960

A Loop For Circulating Liquid Lead-Bismuth Mixtures: Corrosion Studies And Operation , John Charles Clifford

Retrospective Theses and Dissertations

No abstract provided.


The Use Of Some Agricultural Products As Raw Materials In The Plastic Industry , James Alvin Johnston Jan 1938

The Use Of Some Agricultural Products As Raw Materials In The Plastic Industry , James Alvin Johnston

Retrospective Theses and Dissertations

Studies were made of suitable methods of producing plastics from furfural and hydrolyzed cornstalks. It was found that hard, black plastics with a pleasing appearance, high impact strength, and satisfactory water resistance can be produced from a mixture of hydrolyzed cornstalks, furfural, aniline and lime. This material absorbed slightly more than one percent of water in twenty-four hours but it was not discolored, swollen or cracked from the immersion in water. It was estimated that the raw material costs of this plastic would be less than three cents a pound;It was found that hard, black plastics with a pleasing ...


Plastics From High Pentosanocellulosic Material , William Donald Harris Jan 1934

Plastics From High Pentosanocellulosic Material , William Donald Harris

Retrospective Theses and Dissertations

The investigational work was divided into two parts. In the first part, information was obtained as to the nature of the reactions of the individual constituents of high pentosanocellulosic materials with phenol or the cresols in the presence of a catalyst;Cellulose was found to act in two ways; it would either dissolve in phenol and zinc chloride, the zinc chloride acting as a solvent instead of catalyst, or it would undergo decomposition and condense with phenol to form a black, resinous material. Sulfuric acid served also as catalyst in the condensation, while sodium hydroxide did not. The presence of ...