Physical Sciences and Mathematics Commons^™

Polymer Nanocomposite Analysis And Optimization For Renewable Energy And Materials, Nathan Walter Henry

Doctoral Dissertations

Polymer nanocomposites are an important research interest in the area of engineering and functional materials, including the search for more environmentally materials for renewable energy and materials. The ability to analyze and optimize morphology is crucial to realizing their potential, since the distribution of materials in the composite strongly influences its properties. This dissertation presents research into three different polymer nanocomposite systems with three different applications that underscore the need to understand and control the composite morphology to succeed.

The first project details work on development of a copolymer compatibilizer to enhance the dispersion of the plant-derived biopolymer lignin in …

Adsorption Of Hydrogen Onto Bare And Metal Decorated Metal Oxides, Paige Elizabeth Landry

Doctoral Dissertations

Catalytically relevant metal clusters were deposited on metal oxide supports. Palladium and gold were deposited on mixed morphology ZnO, and palladium was deposited on MgO(100). The materials were characterized with electron microscopy, photoluminescent spectroscopy, and X-ray photoelectron spectroscopy. The behavior of hydrogen on these materials, as well as bare ZnO, was studied using volumetric isotherms. The isotherms were used to determine the monolayer gas coverage, surface

area, and heats of adsorption of hydrogen on these materials over the temperature range of approximately 8-13 K. At the temperatures and pressures studied, hydrogen physically adsorbed onto the materials. Additional investigations with inelastic …

Targeted Synthesis And Characterization Of Nanostructured Silicate Building Block Supports And Heterogeneous Catalysts With Tungsten(Vi) Or Zirconium(Iv) Centers, Michael Edward Peretich

Doctoral Dissertations

Catalysts play a vital role in almost every aspect of our lives and are used in the production of fuels, polymers, chemicals, foods, and pharmaceuticals. One challenge facing the heterogeneous catalysis community is the targeted synthesis of dispersed catalyst ensembles.

The Barnes research group has developed a general methodology for the synthesis of nanostructured silicate building block supports and heterogeneous catalysts. This methodology provides researchers with the ability to control the dispersion of surface functionality, the dispersion of metal cation centers, the number of linkages from the metal cation center to the support, the surface area of the support, and …

Development And Application Of Liquid Chromatography-Tandem Mass Spectrometry Methods To The Understanding Of Metabolism And Cell-Cell Signaling In Several Biological Systems, Jessica Renee Gooding

Doctoral Dissertations

Liquid chromatography tandem mass spectrometry has become a powerful tool for investigating biological systems. Herein we describe the development of both isotope dilution mass spectrometry methods and targeted metabolomics methods for the study of metabolic and cell-cell signaling applications.

A putative yeast enzyme was characterized by discovery metabolite profiling, kinetic flux profiling, transcriptomics and structural biology. These experiments demonstrated that the enzyme shb17 was a sedoheptulose bisphosphatase that provides a thermodynamically dedicated step towards riboneogenesis, leading to the redefinition of the canonical pentose phosphate pathway.

An extension of metabolic profiling and kinetic flux profiling methods was developed for a set …

Development Of A Glycoconjugate Tool Set For The Assembly And Presentation Of Carbohydrate Ligands On Surfaces, Irene Esah Abia

Doctoral Dissertations

Carbohydrate and protein interactions are often essential in viral and bacterial infection, the immune response, cell differentiation and development, and the progression of tumor cell metastasis. Therefore, an understanding of carbohydrate–protein interactions at the molecular level would lead to a better insight into the biological process of living systems and assist in the development of therapeutic and diagnostic strategies. Our goal was to synthesize different mannose derivatives, immobilize them on nano-patterned surfaces and carry out binding studies with mannose-binding lectins in order to characterize carbohydrate–protein interactions.

Different derivatives of D-mannose (monosaccharide, (1→2)-linked disaccharide, (1→3)-linked disaccharide, and (1→2, 1→3)-linked trisaccharide) with …

Computational Studies Of Ion Transport In Polymer Electrolytes, Hui Wu

Doctoral Dissertations

Improving ionic conductivity and lithium mobility in polymer electrolytes is important for their practical use for battery electrolytes. In this study, a combination of molecular dynamics and Monte Carlo simulations was used to bring insight into lithium ion transport in poly(ethylene oxide) (PEO) with plasticizers and also next to alumina solid surface doped with lithium salt. The simulations were performed using a moderately high molecular weight polymer (Mn = 10,000 g/mol) at an EO:Li ratio of 15. For the plasticized system, the PEO with LiN(CF3SO 2)2 (LiTFSI) was mixed with 10 wt% plasticizers that included either cyclic ethylene carbonate …

Advanced Techniques In Mass Spectrometry For Qualitative And Quantitative Protein Characterization, Andrew Boissy Dykstra

Doctoral Dissertations

Though mass spectrometry has earned a central role in the field of proteomics due to its versatility in a wide range of experiments, challenges and complications are still encountered when using mass spectrometry to characterize protein structures, post-translational modifications (PTMs), and abundances. In this dissertation, analytical methods utilizing mass spectrometry have been developed to address challenges associated with both qualitative and quantitative protein characterization. The effectiveness of using multiple pepsin-like proteases, both separately and in mixtures, combined with online proteolysis using a special triaxial probe has been demonstrated on an amyloid beta peptide related to the onset of Alzheimer’s disease. …

Liquid Extraction Based Surface Sampling: Liquid Microjunction Surface Sampling Probes Coupled With Mass Spectrometry, Matthew John Walworth

Doctoral Dissertations

The direct sampling of analytes from surfaces under atmospheric conditions followed by mass spectrometric analysis is an ever expanding area of scientific research. Atmospheric pressure surface sampling and ionization techniques for mass spectrometry (MS) offer the ability to interrogate samples that could not be studied under vacuum conditions required of more traditional MS surface analysis techniques. The geometry and nature of materials or surfaces that can be analyzed has been greatly expanded as a result. This dissertation characterizes and shows applications of liquid microjunction surface sampling probe (LMJ-SSP) electrospray ionization systems. The presented work compares traditional analytical work flows with …

Homogeneous And Heterogeneous Approaches To 1,2,4-Triazine-Accelerated Copper-Catalyzed Azide-Alkyne Cycloadditions, Ashleigh Lauren Prince

Doctoral Dissertations

Over the last decade, the domain of click chemistry has grown exponentially and has significantly impacted the fields of organic synthesis, medicinal chemistry, molecular biology, and materials science. The ideal model of a click reaction has become the copper-catalyzed azide-alkyne cycloaddition (CuAAC). Inherent limitations of CuAAC, including high temperatures, long reaction times, and difficult purifications, have been minimized by the development of nitrogen-based ligands. Herein, we present a novel application of 1,2,4-triazines by investigating their use as accelerants for CuAAC.

A diverse library of 1,2,4-triazines were synthesized in order to examine the molecular determinants of their catalytic activity. These ligands …

The Elucidation Of Stationary Phase Treatment Effects In Enantiomeric Separations, Joel Garrett Putnam

Doctoral Dissertations

Acid/base modifiers are sometimes used as additives in the elution on columns packed with amylose tris(3,5-dimethylphenylcarbamate) stationary phase to separate enantiomers. When modifiers are removed from the mobile phase, the stationary phase is affected in ways that are not understood because of the lack of systematic studies, making the scale-up of preparative separations difficult to predict. Once a column has been exposed to these modifiers, the selectivity of certain pairs of enantiomers may change, for the better or the worse. Numerous pairs of molecules affected by this phenomenon are listed in the literature. Five pairs of these molecules were chosen, …

Thermally Robust Ald And Silver Nanocube Based Plasmonic Probe For High Temperature And Microfluidic Sers Measurement, Joshy Francis John

Doctoral Dissertations

Raman spectroscopy is normally a non-destructive, highly selective technique that has become an ubiquitous tool for analytical chemists. One of the primary limitations of Raman spectroscopy, however, is the relatively low cross-section of the technique. With signal enhancements relative to normal Raman scattering as high as 1011, the ultra-trace detection of adsorbates down to the single molecule level has been achieved with SERS. Despite the dramatic improvement in the sensitivity and the high selectivity afforded by the SERS method, the acceptance of SERS as a general analytical tool has been hindered by a lack of stability and reproducibility in the …

Thermo- And Ph-Sensitive Hydrophilic Block Copolymers: Synthesis, Micellization, Gelation, And Application, Thomas G. O'Lenick

Doctoral Dissertations

This dissertation presents the synthesis of a series of thermo- and pH-sensitive hydrophilic block copolymers and the study of their solution behavior in water. By incorporating a small amount of weak acid or base groups into the thermosensitive block(s) of a hydrophilic block copolymer, the LCST of the thermosensitive block(s) can be modified by changing the solution pH. Accordingly, the critical micellization temperature (CMT) and the sol-gel transition temperature (Tsol-gel) of the block copolymer in water can be tuned. Chapter 1 describes the synthesis of thermo- and pH-sensitive poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid)-b-PEO-bpoly( methoxydi(ethylene glycol) methacrylate co-methacrylic acid) and the study …

Surface-Enhanced Raman Scattering: Substrate Development And Applications In Analytical Detection, Deepak Bhandari

Doctoral Dissertations

To advance the capabilities of surface-enhanced Raman scattering (SERS), we developed a silver modified polypropylene filter (AgPPF) substrate which acts as a pseudo stationary phase in harvesting SERS signatures of so called "phytochemical estrogens" and other environmentally significant chemicals. To augment electron beam lithography (EBL) in SERS research, we also introduced an interesting nanotransfer printing (nTP) technique which could circumvent the low throughput and extremely high resolution (< 10 nm) limitations of EBL in designing advanced SERS substrates. In our study, a nominal average thickness of 10 nm silver on the polypropylene microfiber produced nanoglobules of less than 100 nm in diameter. This noble metal nanoroughened layer allowed AgPPF to serve as a SERS active substrate, onto which the noted endocrine disrupting chemicals were passed through and harvested. The intense, multifeatured vibrational Raman spectra of very rarely SERS studied chemical species collected indicates the potential for useful detection via this approach of creating SERS substrates. AgPPF substrates were also used in characterizing the adsorption behavior of hydroxyl complexes of uranium. Interestingly, hydroxyl group on the uranium complexes showed slow sorption kinetics on the nanostructured silver surfaces. Understanding the adsorption behavior of aqueous solution of uranium on nanostructured silver surfaces has opened up the possibilities of SERS detection of these environmental and non-proliferation concerned species without any surface modifications. nTP is a high resolution printing technique and relies on interfacial chemistries to control the transfer of thin metal film from a "stamp" to a "substrate". In our research, high-aspect-ratio AutoCAD designed nanopatterns were created on silicon wafers using e-beam lithography and reactive ion etching. Silicon relief pillars based stamps were then used to integrate a variety of nanostructures on different dielectric materials. Thus created nanopatterns have shown their promise to hold their inherent SERS activity. For its simplicity, cost-effectiveness, and ease of operation, this hyphenated nTP-SERS technique is impressive in the selection of suitable supporting-films for better SERS enhancements and also to manipulate gap between nanodiscs (gap-plasmonic SERS effect).

Fluorescent Receptors For Biomolecules, Chi-Linh Do-Thanh

Doctoral Dissertations

The development of synthetic receptors capable of high-affinity complexation of biologically relevant analytes in competitive solvent systems represents an ongoing challenge in molecular recognition. Anion recognition is particularly problematic, which is significant since numerous biological processes are regulated by anions, such as those resulting from phosphorylation. In this dissertation, we present the design and synthesis of a fluorescent sensor containing two cyclen groups that are preorganized to form a binding cleft for anion complexation. The receptor design includes a rigid acridine backbone, which is also exploited for fluorescence signal transduction. Furthermore, click chemistry is employed to facilitate receptor synthesis, and …

Synthesis And Binding Studies Of Peptide Mimetics, Anion Receptors, And Kinase Inhibitors, Nanditha G. Nair

Doctoral Dissertations

"A series of novel purine-based fluoroaryl triazoles were synthesized and assayed for their neuroprotective effects of hippocampal slice culture exposed to amyloid beta (Aß) oligomers. A monofluorinated triazole has been identified which has comparable neuroprotective effect as that of flavopiridol and roscovitine against the Aß induced neurotoxicity. Carnosine and histidine are biologically interesting antioxidants. In order to probe whether they exert their antioxidant effect through metal ion chelation, the Cu(ll) ion chelating abilities of these compounds were measured by UV-vis spectroscopy. Amyloid beta, the major component of senile plaques in Alzheimer's disease, is known to complex transition metal ions through …

Part-I Characterization Of Phorbol Ester; The Predominant Toxic Component Of Jathropha Curcas And Development Of An Efficient Process For The Detoxification Of Jathropha Curcas Meal Part-Ii Quantification Of 2-Hydroxy-4-(Methylthio) Butanoic Acid And Pantothenic Acid In Bovine Serum And Sea Water Matrices, Balaji Viswanathan

Doctoral Dissertations

"Jatropha curcas is has often been touted as the most sustainable biofuel source. Jatropha curcas is a drought resistant perennial plant belonging to the Euphorbiaceae family. Interest in this plant as a biofuel source is related to high lipid (triglyceride) content of its seeds. However, economics of jatropha as a biofuel source has been marred by the toxicity of the oil and its protein rich meal. As a result of high toxicity the protein rich meal is used only as a very low or no economic value organic fertilizer. Economic return from jatropha can be dramatically enhanced through development of …

Epitaxial Electrodeposition Of Metal Oxide Films And Superlattices Which Exhibit Resistance Switching, Rakesh V. Gudavarthy

Doctoral Dissertations

"This dissertation presents an investigation of the electrodeposition of metal oxide films and superlattices on conducting polycrystalline and single crystal substrates. In the first part of the study, electrodeposition of magnetite (Fe₃O₄) films and superlattices in the magnetite/zinc ferrite system which exhibit resistance switching is studied. Paper I reports the electrodeposition of superlattices in the magnetite/zinc ferrite system and shows that only superlattices exhibit multistate resistance switching. In paper II, simple polycrystalline magnetite films electrodeposited on stainless steel crystals exhibit multistate resistance switching which can be tuned by controlling the composition of the films. Paper II describes the epitaxial electrodeposition …

Interfacial Effects On Dielectric Properties Of Polymer-Particle Nanocomposites, Sasidhar Siddabattuni

Doctoral Dissertations

"Dielectric materials that are capable of efficiently storing large amounts of electrical energy are desirable for many electronic and power devices. Since the electrical energy density in a dielectric material is limited to εV_b²/2, where ε is the dielectric permittivity of the material and V_b is the breakdown strength, increased permittivity and breakdown strength are required for large energy storage density. Interfacial effects can influence the dielectric properties, especially dielectric breakdown resistance in polymer-particle nanocomposites. Several functional organophosphates were used to modify the surface of titania and barium titanate nanofiller particles in order to achieve covalent interface …

Development Of A Versatile Man-Portable Obscurant Aerosol Generator: Characterization Of Aerosols In Laboratory And Field Environments, Robert William Schaub

Doctoral Dissertations

"The objective of research presented in this dissertation was to develop a readily deployable and environmentally benign obscurant system operating with a single liquid for the visible and near infrared regions. To achieve this objective, research efforts were directed in two areas: i. Evaluating suitable biogenic oils to replace the United States Army's "Fog Oil" as the obscurant fluid. ii. Design, fabrication and validation of a prototype man-portable / vehicle mountable modular obscurant aerosol generator. Petroleum middle distillate - "Fog Oil" has been the material of choice for wide area obscuration for several decades. Large quantities (thousands gallons) of the …

Investigation Of Occurrence, Elimination And Degradation Of Pharmaceutical And Personal Care Products In Drinking Water Using Liquid Chromatography-Tandem Mass Spectrometry, Chuan Wang

Doctoral Dissertations

"Pharmaceutical and personal care products have benefited humans and animals around the world. However, their presence in natural and treated water system as emerging contaminates may have potentially adverse effects on the aquatic environment and cause development of bacterial resistance. In this research project, a comprehensive liquid chromatography tandem mass spectrometry method has been developed and validated for the analysis of sixteen pharmaceutical compounds using solid phase extraction. Treated and untreated water samples collected across Missouri from water treatment facilities were analyzed to access the distribution of sixteen pharmaceutical compounds in both winter and summer seasons. The results of the …

Aerogels And Films Through Free Radical Polymerization, Anand G. Sadekar

Doctoral Dissertations

"Aerogels are porous lightweight materials, unique among all solids in terms of low density, low thermal conductivity, low dielectric constants and high acoustic attenuation. The penalty for those exceptional properties is fragility. That issue has been addressed by bridging covalently (crosslinking) the elementary nanoscopic building blocks of silica aerogels with polymers. To streamline the crosslinking process we synthesized a bidentate free radical initiator (Si-AIBN) that gets attached on the skeletal nanoparticles and induces crosslinking by surface initiated polymerization (SIP). Here, we extend the scope of Si-AIBN in two directions: (a) we demonstrate extremely adhering, covalently attached polymer coatings on oxidized …

Preliminary Model Development Of Metal Complexation Of Polyester Derivatives Of 2,2'-Biimidazole, Shelonda Rena Taylor Finch

Doctoral Dissertations

"The objective of this study was to develop a chemical model for metal ion complex formation by a macroligand system with multi-metal binding sites using 2,2'-biimidazole as the starting molecule of the ligand system. Prior studies in this laboratory guided the selection of diesters and hydroxyethyl derivatives of 2,2'-biimidazole as model monomers. In addition, metal ion complexation studies with 2,2'-biimidazole derivatives were conducted. As a result, crystal structures of 1,1'-di(methylpropionato)-2,2-biimidazole, 2,2'-bis(1H-imidazolium) dinitrate and silver 2,2'-bis(1H-imidazolium) trinitrate, were reported. The crystal structures indicated a dependence upon the binding ability of the protonated 2,2'-biimidazole and counter ions. transesterification of the diesters and …

One Pot Synthesis Of Metal, Carbides And Polymeric Aerogels, Naveen K. Chandrasekaran

Doctoral Dissertations

"Ultra-low density, three-dimensional assemblies of nanoparticles are referred to as aerogels, and typically are derived from supercritical fluid (SCF) drying of wet-gels. Aerogels are generally fragile materials, but that issue has been addressed successfully by X-aerogels, in which the inorganic nanoparticle framework plays the role of the template for the accumulation of polymer that connects covalently and crosslinks the nanoparticles. The resulting materials can be 300x stronger than the native network, for a nominal increase in density by a factor of 3x. Since the exceptional mechanical properties of X-aerogels are traced to the conformal polymer coating, it was reasonable to …