Physical Sciences and Mathematics Commons^™

Adsorption Of Propane On The Magnesium Oxide (100) Surface And Synthesis Of Anodized Aluminum Oxide, Michael John Felty

Doctoral Dissertations

This work is divided into two parts: the adsorption of propane on the magnesium oxide (100) surface and the synthesis of anodized aluminum oxide. The adsorption properties of propane on the MgO (100) surface were investigated using high-resolution volumetric isotherm techniques and a computational study was accomplished using Materials Studio. From the adsorption work, the two-dimensional isothermal compressibility, the isosteric heat of adsorption, the differential enthalpy, and the differential entropy of adsorption can be calculated. Three distinct layers of propane were observed to form on the MgO (100) surface and it was determined that a phase transition occurs at 162 …

Molecular Hydrogen Adsorbed On Mgo (100) Surfaces: A Thermodynamic Study, Lillian Ruth Frazier

Doctoral Dissertations

The thermodynamics of molecular hydrogen adsorbed on MgO (100) surfaces has been examined using high resolution volumetric adsorption isotherm techniques. These studies were undertaken using highly perfect, narrow size distributed MgO nanocubes with essentially single (100) facet exposure and extremely high chemical purity. A narrowly spaced (in temperature) series of isotherms were performed between the temperatures of ~7K and the triple point (13.8 K) using H₂ and D₂ gas.

A minimum of five, and in some cases seven, discrete adsorption steps are clearly observed in each isotherm trace. Analysis of these data indicate that the monolayer film forms …

New Carbon-Carbon Bond Forming Reactions Mediated By Boron And Transition Metal Halides, Travis R. Quick

Doctoral Dissertations

This dissertation summarizes the recent use of boron and transition metal halides to form new carbon-carbon bonds. Several novel reactions have been discovered. These include the haloallylation of aryl aldehydes with boron trihalide; alkyne-aldehyde couplings mediated by boron trihalide to give either (Z,Z)-1,5-dihaloalkenes or (Z,E)-1,5- dihaloalkenes; dehydroxylation of benzylic alcohols and in situ generated benzylic alcohol salts with iron(III) chloride and triethylsilane to afford diarylmethanes; and, the alkenylation of allylic, benzylic, and propargylic alcohols with phenylacetylenes and titanium(IV) halide. The results of these studies strongly imply a cationic mechanism. The reaction methodology of the research described herein can be characterized …

Synthesis Of Two Thiol-Terminated Disaccharides And A Mannose-Branched Glycodendrimer, Chao Wang

Doctoral Dissertations

The glycocalix, a complex structure of lipids and glycoproteins, forms the cellular surface of all cells and serves to mediate a variety of events such as cell–virus recognition, cell–cell recognition, immunological response, metastasis, and fertilization. Moreover, the glycocalix is specific for a particular species, cell type, and developmental status. Alterations in the glycocalix have been found in association with many pathological conditions such as cancer and tuberculosis. Investigation of the interactions between the glycocalix and its associated proteins will lead to a fundamental understanding of these important processes.

Multivalent interactions are characterized by the simultaneous binding of multiple ligands on …

Advancing Data Analysis For Spectroscopic Imaging By Combining Wavelet Compression With Chemometrics, Robert Daryl Luttrell

Doctoral Dissertations

Spectroscopic imaging is a vital tool for studying heterogeneous samples such as bacteria and tissue. Its ability to acquire spatially resolved information allows for identification and classification of the various constituents within a sample. Spectroscopic imagers quickly acquire thousands to tens of thousands of spectra per measurement. These data are often arranged in the form of a 3-dimensional (3D) data cube which contains two spatial dimensions and one spectral dimension. This large amount of data is beneficial for gaining a thorough understanding about the distributions of chemical information. If too little information is measured, important chemical behavior may be overlooked. …

The Rational Design And Lithographic Fabrication Of Surface Enhanced Raman Spectroscopy Substrates, Jenny M. Oran

Doctoral Dissertations

The analytical capabilities of surface-enhanced Raman spectroscopy (SERS) reside in the performance characteristics of the SERS-active substrate. Signal enhancement observed in SERS is attributable to the presence of noble metal nanostructures on substrate surfaces. The rational design and control of variables such as shape and size, and distribution, density, and spacing of these nanostructures can lead to substrates that have greater analytical sensitivity and yield more reproducible enhancement. Through systematic control of the morphology of our SERS substrates, we have created ordered periodic arrays as well as random aggregates of nanoscale particles using electron beam lithography (EBL). A unique aspect …

Poly(Ethylenedioxythiophene) Based Electronic Devices For Sensor Applications, Jie Liu

Doctoral Dissertations

Organic electronic devices, based on Poly (3,4-ethylenedioxythiophene)-Poly (styrene sulfonic acid) (PEDOT-PSS) as the active layer for sensor applications, have been studied. Two sets of sensors have been developed. In one case, sensors consisting of PEDOT-PSS resistors have been realized and demonstrated for soil moisture monitoring. The resistor model for the soil moisture sensor enables the sensor device to be fabricated at low cost and easily tested with a simple structure. Unlike the large dimension device used in Time Domain Reflectometry (TDR), the sensors are small and are capable of capturing microscale behavior of moisture in soil which is useful for …

Novel Approaches To Prepare And Utilize Sers Substrates: Multiplex Microfluidics And Nanotransfer Printing, Nahla A. Abu-Hatab

Doctoral Dissertations

Over the past few decades, surface enhanced Raman spectroscopy (SERS) has garnered respect as an analytical technique with significant chemical and biological applications. SERS is important for the life sciences because it can provide trace level detection and a high level of molecular structure information. The development of quantitative, highly sensitive substrates requires control over size, shape, and position of metal nanoparticles which function as the SERS active medium. Thus, creating and successfully implementing a sensitive, reproducible, and robust SERS active substrate continues to be a challenging ask. Its future development depends critically on techniques for lithography and nanofabrication. Herein, …

Approaches To Generating Selectivity In Microcantilever Sensors, Peter J. Chapman

Doctoral Dissertations

Microcantilever (MC) sensors have emerged as sensing transducers that offer greater sensitivity than comparable sensors due in large part to their very small dimensions. MCs have been utilized in many chemical sensing applications. Not only do MCs demonstrate greater sensitivity, but they also are relatively low in cost, they can be used in an array format, and they can be integrated into on-chip electronic circuitry.

While MC sensors demonstrate great sensitivity, an area of weakness that MC sensors must overcome is that of selectivity. The response of a MC sensor to analyte is mechanical; these mechanical responses lack the information …

Materials Chemistry Of Nanocubes And Mesoporous Silicas: Characterization And Adsorption Studies, Sami Ziad Chanaa

Doctoral Dissertations

Metal oxides (MO) and their surfaces play a vital role in numerous phenomena, including metal surface passivation, catalysis, integrated optoelectronic technology, and pollution monitoring via solid-state gas sensing. This experimental study seeks to aid in the development of accurate and predictive theoretical models of the potential energy surfaces described in the interaction of these small molecules with the magnesium oxide (MgO) substrate. MgO, with its structural simplicity and capacity to be fabricated with a predominantly (100) exposed face, is an ideal representative of the MO family popular for both experimental and theoretical studies. Using high-resolution volumetric adsorption isotherms, a thermodynamic …

Establishment Of A Structure-Activity Relationship In Heterogeneous Titanosilicate Catalysts For Olefin Epoxidation Via A Building Block Method, Geoffrey T. Eldridge

Doctoral Dissertations

The non-aqueous building block (NABB) method is a synthetic method that has the goal of producing atomically dispersed, well-defined, single-site heterogeneous catalysts. The active sites of these catalysts are able to be structured on the nanometer scale using the process of sequential additions. The method is designed in such a manner that it should be able to produce a series of catalysts each with a unique, well-defined, single active site. This series of catalysts can then be used to elucidate the structure-activity relationship for the active site in a particular chemical reaction.

In this dissertation a new building block, …

Synthesis, Characterization, And Applications Of Responsive Polymer Brush-Grafted Particles, Dejin Li

Doctoral Dissertations

In this dissertation, I present the synthesis, characterization, and applications of responsive polymer brush-grafted silica/crosslinked polymeric particles. The polymer brush-grafted particles were synthesized by surface-initiated "living"/controlled radical polymerizations from initiator-functionalized particles in the presence of free initiators. Two types of core particles were used in my research. One was silica particles, which were synthesized by Stöber method. The other one was crosslinked PtBA particles, which were prepared by seeded emulsion polymerization. The responsive properties of the grafted polymer brushes were characterized with ¹H NMR and Dynamic Light Scattering.

Synthesis And Evaluation Of Vegetable (Soybean) Oil Based Epoxy Resin For Beverage Can Coating And Enzymatic Synthesis And Characterization Of Tailored N&C End Protected Oligopeptides, Ying Gao

Doctoral Dissertations

"Research described in this dissertation covers two topics. Part-I is related to the development of a soybean oil based epoxy resin and its application in beverage can coatings. Interior surfaces of beverage can are invariably coated with polymer coating. The most commonly used coatings at present are derived from bisphenol A (BPA) based epoxy reins. However, due to perceived endocrine disrupting nature of BPA and consequential adverse effects on humans and wildlife concerns for the use of BPA based coatings and its leaching into beverages have been expressed. The research in the first part describes the synthesis and evaluation of …

The Effect Of Free Chlorine And Monochloramine On Lead In Drinking Water And Epitaxial Electrodeposition Of Tin Sulfide, Sansanee Boonsalee

Doctoral Dissertations

"Electrochemical deposition is utilized in various electronic and photovoltaic applications and in the protective coating industries. This dissertation primarily addresses the environmental aspects of electrochemical deposition. In the first part of this study, Pb dissolution in drinking water was investigated in the presence of two disinfectants: free chlorine (in the form of HOCI/OCr) and monochloramine (NH₂Cl). In the second part of this study, epitaxial SnS nanodisks were electrodeposited onto a Au(100) substrate. Water utility systems use either free chlorine or monochloramine in their disinfection program. Whereas free chlorine reacts with natural organic matter in the water to produce halogenated organic …

A Tour-De-Force In Polymer Crosslinked Aerogels, Sudhir Mulik

Doctoral Dissertations

"In the quest of building mechanically strong materials with low density and high porosity, polymer crosslinked aerogels stand as the most promising nano-engineered examples. Covalent attachment of polymers and bridging of skeletal nanoparticles of typical aerogels is demonstrated by using surface initiated polymerization (SIP) with a bidentate free-radical initiator structurally related to azobisisobutyronitrile (AIBN) and confined on mesoporous silica surfaces. Different monomers were introduced in the mesopores and upon heating at 70⁰C, all mesoporous surfaces throughout the entire skeletal framework were coated conformally with a 10-12 nm thick polymer layer indistinguishable spectroscopically from the respective commercial bulk materials. The new …