Physical Sciences and Mathematics Commons^™

Hydroxy Polybenzimidazoles For High Temperature Fuel Cells And The Solution Polymerization Of Polybenzimidazole, Kayley Fishel

Theses and Dissertations

In this dissertation, two different hompolymers of polybenzimidazole (PBI) containing hydroxyl functional units were synthesized via the PPA Process to produce gel membranes. These polymers and their phosphoric acid doped membranes were characterized to further explore structure-property relationships in functionalized PBI's. Fuel cell performance of the doped membranes was evaluated and compared to previously reported PBI membrane chemistries. Copolymers of p-OH PBI and para-PBI were prepared at five different copolymer compositions to examine the effects of hydroxy content on membrane properties and compared to the respective homopolymers. The reactivity of the hydroxy groups and the formation of phosphate bridges were …

Defining The Effects Of Gdf-2 On TgfB Signaling In Tumorigenic Epithelial Cells, Tirthankar Bandyopadhyay

Theses and Dissertations

Cancer cells can be viewed as such cells, which have disrupted/aberrant signaling pathways for maintaining cellular homoeostasis. Identifying such altered signaling mechanisms can help us target these pathways in a better way. GDF-2 (Growth and differentiation factor – 2) or BMP9 (Bone morphogenetic protein – 9), a multifunctional cytokine, is a member of the Bone Morphogenetic Protein subfamily, under TGFβ superfamily, with roles distinct from BMP2/4/7. While GDF-2 is known to be one of the most potent ectopic inducers of bone and cartilage formation, it rose to significance with the identification of its receptor ALK1 in endothelial cells. TGFβ’s role …

Optimized Spectral Processing Of Infrared Diffuse Reflection Spectra For The Detection Of Blood On Fabric, Stephanie Ann Dejong

Theses and Dissertations

The detection of bodily fluids such as blood on interfering backgrounds is important to the forensic community. Luminol, which participates in a chemiluminescent reaction with the heme groups of blood, is one of the most commonly used presumptive tests. Luminol has a few drawbacks, including the requirement of use in a dark environment and potential to degrade the amount of recoverable DNA in blood stains. A potential complementary method is infrared (IR) spectroscopy. These two methods are compared in this work. Infrared diffuse reflection (DR) spectroscopy works well to measure the IR spectrum of samples that are highly absorbing or …

Two-Dimensional Transient Spectroscopy Measuring Heterogeneity In Electronic And Rotational Dynamics, Haorui Wu

Theses and Dissertations

Multiple population-period transient spectroscopy (MUPPETS) is a picosecond, time resolved experiment that uses a sequence of six laser pulses. It was previously known that MUPPETS could measure heterogeneity in electronic-state decay. This dissertation presents two projects that extend MUPPETS to new processes. One process is the extension from 2-level system into 3-level system, another new process extends the kinetics from electronic decay to rotational decay. In addition, a third, ongoing project on rotational dynamics in ionic liquids will also be discussed briefly. The first project consisted of two main parts. The first part focused on the biexciton decay in semiconductor …

Optimization Of Shell Growth And Influence Of Surface Ligands For Colloidal Cdse/Cds Core/Shell Quantum Dots, Rui Tan

Theses and Dissertations

Progress in the colloidal synthesis of semiconductor quantum dots (QDs) has triggered a burst of research toward applications in QD based light emitting diodes, biological imaging as fluorescent tags, and advanced solar cell designs. In order to adjust and optimize the photo physical properties of QDs, QD heterostructures have been introduced and widely explored. This dissertation is focused on studies of growth of semiconductor colloidal CdSe/CdS core/shell quantum dots and the influences of neutral surface ligands to their photo-physical properties. Chapter 1 provides an introduction of the concept of semiconductor colloidal nanoparticles, core/shell heterostructures and the synthesis methods as well …

Applications Of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy For Forensic Analysis, Zhenyu Lu

Theses and Dissertations

Blood stains, which are among the traces encountered most frequently at crime scenes, are important for potential extraction and amplification of DNA for suspect identification, as well for spatter pattern analysis to reveal a sequence of events. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used in detection of blood stains and age estimation because of signature absorbances in the mid-infrared region at 3300 cm-1 (Amide A), 2800-3000 cm-1 (Amide B), ~1650 cm-1 (Amide I), ~1540 cm-1 (Amide II) ,and 1200-1350 cm-1 (Amide III). Position and intensity shifts for amide peaks were observed due to aging changes occurring as …

Approaching Aromatic Interactions With Small Molecule Model Systems: Assessing N-Heteroarene In ∏ -Stacking And Ch-∏ Interactions, Crystal Engineering Of Atropisomeric Rotors, And Developing Responsive Organic Charge-Transfer Complex, Ping Li

Theses and Dissertations

Non-covalent interactions involving aromatic species are important in many areas in chemistry, biochemistry, and materials sciences. During the past two decades, small molecule model systems have emerged as a powerful tool to advance our knowledge of the stability trends for aromatic interactions in the condensed phase. Among these, the Cshape N-arylimide molecular balances developed by our laboratory have proven to be one most successful and versatile model systems that can be readily adapted to investigate various types of aromatic interactions. These molecular balances are particularly apt at isolating and accurately measuring the targeted weak aromatic interaction energies for different geometries. …

Optical Spectroscopy And Chemometrics For Discrimination Of Dyed Textile Fibers And Magnetic Audio Tapes, Nathan C. Fuenffinger

Theses and Dissertations

This dissertation focuses on the application of both novel and standard chemometric approaches toward societal problems of interest in the areas of forensic science and cultural heritage preservation. Microspectrophotometry (MSP), a technique enabling measurements of absorption of electromagnetic radiation by microscopic materials in the ultraviolet-visible (UV-Vis) region, is widely used by forensic examiners for comparisons of metameric textile fibers. These comparisons are often hindered, however, by the raw or normalized spectra showing little detail or having few points of comparison. Derivative preprocessing can enhance structure in some instances. We have demonstrated through the use of multivariate statistics that derivatives are …

Spectroscopy And Chemometrics For Cultural Heritage And Forensics: Conservation Of Magnetic Tape By Identifying Degraded Polymer Signatures; And Characterizing The Chemiluminescent Reaction Of Luminol With Blood, Brianna Marie Cassidy

Theses and Dissertations

The first half of this manuscript focuses on the identification of degraded magnetic tape using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and multivariate statistics. For several decades before the digital era, magnetic tape was the dominant audio and visual recording medium. A majority of magnetic tapes contain polyester urethane (PEU) binders, which are known to degrade via hydrolysis, making the retrieval of recorded data difficult and at times impossible. Degraded tapes are currently identified through visual inspection followed by playback on vintage equipment. However, if degraded tapes are played, they are likely to stick and shed onto player …

Supramolecular Coordination Networks Of S- And F-Block Metals Featuring The 1,8-Naphthalimide Tecton, Andrew Paul Leitner

Theses and Dissertations

The reactions of (S)-2-(1,8-naphthalimido)propanoic acid (HLala), and (S)-2-(1,8- naphthalimido)-3-hydroxypropanoic acid (HLser), protonated forms of ligands that contain a carboxylate donor group, an enantiopure chiral center and a 1,8-naphthalimide π...π stacking supramolecular tecton and in the case of HLser an alcohol functional group, with the appropriate alkali metal hydroxide followed by a variety of crystallization methods leads to the formation of crystalline K(Lala)(MeOH) (1), K(Lala)(H2O) (2), Na(Lala)(H2O) (3), KLser (4), CsLser (5) and CsLala (6). Each of these new complexes has a solid state structure based on six-coordinate metals linked into homochiral helical rod SBU central cores. In addition to the …

Sustainable Polymeric Materials Derived From Novel Soybean Based Monomers And Polymers: From Synthesis To Applications, Nathan Trenor

Theses and Dissertations

In this thesis, monomers and polymers derived from high oleic soybean oil are investigated. The properties of these monomers and polymeric materials are characterized and discussed. Chapter 1 describes an overall background of bio-based resources, monomers, polymers, and their potential impact on society. Polymerization techniques are introduced, and the overall objective of my research is described. Chapter 2 outlines the large scale preparation of a soybean based monomer and the use of this monomer in thermoset elastomers. The synthetic procedures and characterizations of the monomers and polymers are discussed. A model study using oleic acid is described and proved to …

Novel Block Copolymer Architectures For Lithography-Relevant Self-Assembly, Jeffery Hakim Hayat

Theses and Dissertations

This dissertation is focused on the synthesis, characterization, self-assembly, and materials processing of various functionalized block copolymer systems. A variety of monomers were prepared and polymerized through various polymerization techniques including atom transfer radical polymerization, reversible addition-fragmentation chain transfer polymerization, and ring-opening metathesis polymerization. Self-assembly of the functionalized block copolymers led to well-defined nanostructures in bulk and thin films. These materials have the capability to be utilized in various applications including ordered catalysts and templates for nanolithography. In Chapter 1, the overall background of diblock and triblock copolymers and their preparation methods is in this dissertation. Major research objectives of …

Facile Method For Large Scale Alignment Of One Dimensional Nanoparticles And Its Biomedical Application, Sheng Feng

Theses and Dissertations

Topographical cues can profoundly affect cellular behaviors. This thesis investigate how to utilize the topographical cues generated by two techniques, flow assembly and electrospinning, to regulate cellular behaviors.

First of all, a facile and robust method to align one-dimensional (1D) nanoparticles (NPs) in large scale has been developed. Using flow assembly, representative rod-like nanoparticles, including tobacco mosaic virus (TMV), gold nanorods and bacteriophage M13, have been aligned inside capillaries by controlling flow rate and substrate surface properties. The properties of 1D NPs, such as stiffness and aspect ratio, play a critical role in the alignment. Furthermore, these hierarchically organized structures …

Metals On Titania/Hopg As Models For Heterogeneous Catalysts, Randima Piyumalie Galhenage

Theses and Dissertations

The work done in this thesis is mainly focused on understanding the nanoscale morphology and activity of model heterogeneous catalysts. In order to do this we design and prepare model catalytic surfaces in ultrahigh vacuum (UHV) and study these surfaces using electron and ion based microscopies and spectroscopies. The nucleation, growth and chemical activity of mono and bimetallic clusters on TiO₂(110) were investigated in order to understand how activity is influenced by cluster sizes, interactions with the oxide support and surface compositions of the bimetallic clusters. For example, Au-based and Pt-based bimetallic clusters such as Co-Au, Co-Pt, and …

Impact Of Ocean Acidification On Aphotic Biogeochemical Production Of Reactive Oxygen Species, Sarah Ann Murphy

Theses and Dissertations

Reactive oxygen species (ROS) are critical to global maintenance of the global organic carbon cycle, sulfur cycle, oxygen cycle, and transition metal cycles. The primary source of ROS is commonly considered to be photolysis or photochemically driven reactions, however ROS also exist in aphotic zones. A geochemical mechanism for the same in dark environments based on the tidally driven, episodic movement of anoxic groundwaters through oxidized, Fe(III) rich sediments is shown. Predictive models were developed based on in vitro experiments and tested using sediment samples collected from a saline tidal creek in the estuary at Murrell’s Inlet, South Carolina. These …

Applications Of Organic Probes For Imaging And Analysis Of Different Cancer Cell Models, Hong Guan

Theses and Dissertations

Novel techniques for better studying cancer cell behavior and progression are extremely important. Our lab is interested in synthesizing specifically designed organic reagents and applying them in the studies of cancers. In this dissertation, we used organic probes to investigate cancer cells in the following topics: determination of amino acid concentration in different types of cancers, tumor toxicity of organic probes towards HER2 positive breast cancer cells, glycoproteins identification in breast cancer cells and development of enzyme activity assay for colon cancer cells.

The first chapter was focused on the determination of cysteine/homocysteine concentrations using turn-on sensors in cancer cells. …

Modification Of Nanoparticles For Designed Interfaces, Tony Lee Neely, Jr.

Theses and Dissertations

The work contained herein, is focused on the design, synthesis, and characterization of polymer nanocomposite interfaces and the property enhancement afforded from said interface design. Through the use of reversible addition fragmentation chain transfer (RAFT) polymerization for the grafting of polymer chains to silica nanoparticles, the surface of silica nanoparticles can be manipulated to tune the properties of the nanocomposite as a whole.

In the first part of this work, heterogeneity is introduced onto the surface of silica nanoparticles via a sequential RAFT polymerization to afford a bimodal brush system. A densely grafted, short brush population is polymerized from the …

Illuminating The Interactions And Functions Of Glutaredoxins, Bola Proteins, And Erv1 In Iron Homeostasis, Adrian Colleen Dlouhy

Theses and Dissertations

Iron is a redox-active protein cofactor required for essential cellular functions such as respiration, however excess intracellular iron can generate damaging reactive oxygen species. Understanding how cells regulate iron levels is critical for treatment of human diseases that span from anemia to iron overload disorders. Glutaredoxins (Grxs) with a CGFS active site are highly conserved proteins shown to have roles in iron homeostasis and iron-sulfur cluster assembly, thus earning them the title “the Iron Whores”. They can exist either as a [2Fe-2S] cluster-bound dimer or an apo monomer, suggesting conservation of structure and function. In addition, Grxs interact with the …

The Development Of Efficient Geminal-Based Methods For Quantum Chemical Calculations, Brett Allen Cagg

Theses and Dissertations

Incorporation of electron correlation to improve the accuracy of computations remains a driving force in quantum chemical method development. Traditionally, electron correlation effects are divided into static and dynamic correlation parts, and the inclusion of both results in methods that are impractical for large chemical systems. The goal of this doctoral research is to develop a method that efficiently accounts for both components of electron correlation in a separate but balanced manner. The approach focuses on combining a geminal method, called the antisymmetrized product of singlet-type, strongly orthogonal geminals (SSG), with dynamic correlation by either density functionals or a recently …

Chemical Processes Governing The Equilibrium Between Organic And Inorganic Carbon: Probing The Mechanisms Of Iron Catalyzed Reactive Oxygen Species Production, Joy Kelechi Ihekweazu

Theses and Dissertations

This study examines the oxidation of organic carbon that occurs concurrently with the autoxidation of Fe(II) to determine the role that geochemical constituents have on both the autoxidation of Fe(II) and subsequent ROS production. The reaction between reduced carbon and oxygen is thermodynamically favorable, but kinetically proceeds slowly. Fe(II) facilitates the equilibration of reduced carbon and oxygen. This equilibration occurs naturally in saline estuaries, where oxygen rich seawater mixes with anoxic groundwater. We characterized a saline estuary at the Baruch Institute and used those characterizations to recreate natural water conditions in the lab. Using simulated natural water we then examined …

A Silylation-Based Kinetic Resolution Of Hydroxy Lactones And Lactams With Subsequent Mechanistic Investigations, Robert W. Clark

Theses and Dissertations

The work contained herein focuses on the methodology and design of new reactions for the production of stereoenriched compounds. The primary focus of research discussed is kinetic resolution, a classic and powerful methodology for the separation of a single enantiomer from a racemic mixture. In 2011, a silylation-based resolution catalyzed by a chiral isothiourea produced synthetically useful selectivity factors for mono-functional secondary alcohols. In chapter 2, this methodology was subsequently expanded to include α-hydroxy lactones with selectivity factors up to 100. This study resulted in the most selective reaction reported to date for the aforementioned silylation-based resolution. In addition to …

Iridium – Bismuth Carbonyl Cluster Complexes: New Directions For Chemistry And Selective Oxidation Catalysis, Gaya R. Elpitiya

Theses and Dissertations

CHAPTER 2 The reaction of Ir3(CO)9(μ3-Bi), 2.1, with BiPh3 has yielded a iridium−bismuth cluster complex Ir5(CO)10(μ3-Bi)2(μ4-Bi), 2.2. The first examples of bimetallic iridium−bismuth nanoparticles have been subsequently synthesized from 2.1 and 2.2, and these have been securely anchored onto the inner walls of mesoporous silica. These isolated, bimetallic iridium−bismuth nanoparticles display a superior catalytic performance, when compared to their analogous monometallic counterparts and equivalent physical mixtures, in the C−H activation of 3-picoline to yield niacin.

CHAPTER 3 The reaction of Ir3(CO)9(μ3-Bi) with Ph3GeH yielded the compound Ir3(CO)6(GePh3)3(μ3-Bi)(μ-H)3 3.1 When 3.1 was heated to reflux in hexane, it was transformed into …

Assessing The Magnitude And Impact Of Seawater/Pore Water Exchange In Salt Marsh Systems, Carrie Lee Milliken

Theses and Dissertations

Submarine groundwater discharge is a hydrological process that is important to study and understand as it impacts biogeochemical processes and hydrological cycles. Particularly in coastal salt marsh systems, it is an important process to analyze as these systems serve as crucial interfaces between terrestrial and marine waters and particulates. There is evidence that these systems, typically thought to have little exchange across the interface due to impermeable sediments, could actually allow for significant flow of water and particulates at shallow depths. In order to measure and quantify this flow, a method using 224Ra as a tracer has been tested. The …

The Role Of Intermembrane Space Redox Factors In Glutathione Metabolism And Intracellular Redox Equilibrium, Hatice Kubra Ozer

Theses and Dissertations

The mitochondrial intermembrane space (IMS) is a unique subcellular compartment that houses key thiol-dependent redox pathways such as protein transport, mitochondrial respiration, and detoxification of ROS (reactive oxygen species). These pathways are all dependent on cysteine-rich proteins, thus maintaining thiol-disulfide balance in this organelle is crucial for cellular functions. An IMS protein import pathway called the Mia40-Erv1 disulfide relay system uses disulfide bond formation for the import and retention of substrate proteins in the IMS. Erv1 is also suggested to be involved in maturation of cytosolic Fe-S cluster proteins and regulation of iron homeostasis in S. cerevisiae. However, these studies …

Novel Sustainable Polymers Derived From Renewable Rosin And Fatty Acids, Perry Wilbon

Theses and Dissertations

In the work of this dissertation, polymers derived from renewable bio-based resources prepared by various polymerization techniques were investigated. The properties of these polymeric materials were characterized and discussed. Rosin was first converted into acrylate or methacrylate monomers for atom transfer radical polymerization (ATRP). Second, rosin was combined with vegetable oil to produce completely renewable novel polyesters by acyclic diene metathesis (ADMET) polymerization. Third, degradable block copolymers were synthesized composed of polycaprolactone and rosin grafted polycaprolactone with the aid of ring-opening polymerization (ROP). Finally, degradable polyesters were produced using vegetable oil derivatives as starting materials. These new rosin and fatty …