Physical Sciences and Mathematics Commons^™

Evaluation Of Electron Donor Materials Used To Create Subsurface Permeable Reactive Barriers For Enhanced Reductive Dechlorination Of Chlorinated Ethenes, Elizabeth S. Semkiw

Dissertations

Chlorinated ethenes (CEs) are widespread ground water contaminants, apparently due to their extensive migration from numerous contamination source points. In this study, a long-term field investigation and aquifer microcosm experiments were combined to evaluate the effectiveness of electron donor materials used to create and maintain subsurface permeable reactive barriers (PRBs) for the enhanced in-situ biodegradation of CEs. The laboratory component includes the first side-by-side comparison of electron donor materials dairy whey, lactate syrup, and Hydrogen Release Compound® (HRC), in which dechlorination rates, fermentation product distributions, and H₂ production were monitored as measures of substrate efficiency. Field study allowed the …

Switch On And Switch Off Nanosensors For The Detection Of Nerve Gas Agents, Shankar Varaganti

Dissertations

The central hypothesis of this research is the development of novel nanosensors by a bottom-up approach for the detection of nerve gas agents. The nanosensor assembly consists of four main parts; nanoparticles (N), Monomer (M), Complex (C) and Receptor (R). Two novel Ru (II)-bipyridyl and zinc complexes with tryptophan receptors either in 4,4' or 5,5' position of the bipyridyl ring have been synthesized and characterized by using ¹H NMR, ¹³C NMR, mass spectrometry and absorption spectroscopy. Silica nanoparticles or quantum dots are used as a platform for the nanosensors. Highly conjugated stilbene type compounds are used as monomers. …

Reduction Of Toxicity In The Premature Neonate Addociated With Aluminum As A Contaminant Of Total Parenteral Nutrition Solution, Sujittra Srisung

Dissertations

Aluminum (Al) is the third most common element in the Earth?s crust. It is widely consumed in water, foods, and drugs. However, in humans, the uptake of aluminum into the body and its deposition in tissues has been linked to conditions of medical concern, including many neurological disorders such as dialysis dementia, Alzheimer?s disease, Parkinson?s dementia and Down?s syndrome. Premature neonates who receive intravenous feeding (TPN) are at a high risk for Al toxicity because the TPN solutions are contaminated with Al3+, which is not excreted effectively due to poor kidney development in these patients. The FDA has recommended regulations …

On The Rolling Motion Of Viscous Fluid On A Rigid Surface, Xinli Wang

Dissertations

This thesis considers two closely related problems. First, the influence of insoluble surfactant at a moving contact line is considered. This work is mostly motivated by the air entrainment during the coating process where there is a three-phase contact point (e.g., air, liquid and solid). For moving contact line problems, when the fluid is assumed to be an incompressible Newtonian fluid and a no-slip boundary condition is enforced at the solid boundary, the non-integrable stress singularity arises at the contact line, which is physically unrealistic. The contact angle of 180° is considered as a special case in which the singularity …

A Mathematical And Computational Exploration Of The Effect Of The A-Current In Determining The Activity Phase Of Follower Neurons, Yu Zhang

Dissertations

Bursting oscillations are prevalent in neurons of central pattern generators (CPGs) that produce rhythmic motor activity, and the activity phase plays an important role in determining the normal or dysfunctional network output. The activity phase is the delay time-with respect to some reference time in each cycle and normalized by the oscillation cycle period-of the onset of action potentials by a neuron. This dissertation investigates how the A-current, in conjunction with other intrinsic properties, sets the activity phase of a neuron driven by inhibition.

This dissertation is divided into two major components. In the first component, methods of dynamical systems …

Flexible Electronics : Materials And Sensor Fabrication, Katherine J. Duncan

Dissertations

This dissertation demonstrates how to fabricate piezoelectric/pyroelectric thin films by using different printing techniques. These techniques could replace vacuum techniques for manufacturing piezoelectric/pyroelectric sensors. Ink-jet, screen and stencil printing techniques were developed to print these devices.

This work outlines attempts to develop a solution processable conductive ink for ink-jet printing. It then details the printing of commercial conductive ink on flexible substrates employing the three printing methods. Raman spectroscopy and Fourier transform infrared spectroscopy, are both used to investigate the structure of the P(VDF-TrFE) films. Optical microscopy is used to investigate the thickness and uniformity of the deposited films. The …

Remote Sensing Studies For The Assessment Of Geohazards: Toxic Algal Blooms In The Lower Great Lakes, And The Land Subsidence In The Nile Delta, Richard H. Becker

Dissertations

Remote sensing techniques provide valuable tools for assessing a wide variety of environmental phenomena. They have been used for monitoring and assessment of various types of geologic and environmental hazards occurring on land, in the air, or in oceans. I present results from two studies, the first of which examines the spatial and temporal distribution of algal blooms in the Great Lakes; the second measures subsidence in the Nile Delta.

In the first study, methodologies to investigate the extent and distribution (temporally and spatially) of algal blooms in Lake Erie and Lake Ontario are studied. Millions of people in the …

Understanding Similarity: Bridging Geometric And Numeric Contexts For Proportional Reasoning, Dana Christine Cox

Dissertations

The concept of similarity is uniquely situated at the crossroads of geometric and numerical proportional reasoning. Although studies have documented the existence and nature of student difficulties with this topic, there exists a gap between documented visual insights of younger children and the quantitative inadequacies of older ones. Using a revised version of the Similarity Perception Test followed by 21 clinical interviews, this study investigated the visual and analytical strategies that are used by middle-school students to differentiate and construct similar figures.

New strategies for construction and differentiation were identified, and three overarching conclusions were drawn from the work. First, …

Identification Of Two Distinct Glutaminyl Cyclase Isoforms In Drosophila Melanogaster, Amanda Thigpen Parker

Dissertations

Sequence analyses revealed two putative glutaminyl cyclase genes in Drosophila melanogaster with greater than 60% amino acid sequence identity to previously identified glutaminyl cyclase in humans. Expression, purification, and characterization of both putative proteins revealed two enzymatically active glutaminyl cyclase enzymes. Comparison of the Drosophila melanogaster glutaminyl cyclase enzymes to the published human glutaminyl cyclase revealed the enzymes were very similar. The Km values obtained were identical to those of human glutaminyl cyclase for three different substrates tested. However, the Drosophila glutaminyl cyclases demonstrated lower turnover numbers. Both Drosophila glutaminyl cyclase isoforms were inhibited by imidazole, imidazole derivatives, and metal …

Towards Development Of A Fully Synthetic Conjugate Vaccine: Investigation Of Structural Analogs Of Streptococcus Pneumoniae Serogroup 6, Archana R. Parameswar

Dissertations

Involvement of complex glycostructures in a variety of damaging and healing processes has already been acknowledged by development of carbohydrate-based vaccines and therapeutics. The bacteria Streptococcus pneumoniae (SPn) have become one of the most frequent causes of pneumonia, bacteremia, and meningitis in the elderly, immunocompromised, and, especially, in young children. SPn has one of the largest public health and economic impacts amongst all bacterial infectious diseases. Over 2 million children die annually worldwide due to pneumonia, accounting for almost 20% of deaths under age five with more than half of these deaths attributed to SPn. Amongst over ninety elucidated SPn …

Synthesis Of Α-Hydroxy And Fluoro Phosphonates And Cyclic Ether-Containing Natural Products, Nongnuch Sutivisedsak

Dissertations

A number of important classes of natural product (eg. amphidinolide C, (-)-centrolobine, etc) contain common structural features of tetrahydrofurans and tetrahydropyrans. This study involved the development of stereoselective mothods for the synthesis of tetrahydrofurans and tetrahydropyrans including the application of allylic hydroxy phosphonates and their derivatives as chiral, non racemic building blocks for the synthesis of biological active molecules. The enantiomeric excess of non racemic α-hydroxy phosphonates and carbonate derivatives prepared via the asymmetric Pudovik reaction can be improved by kinetic resolution. Both chemical and enzyme catalysts were utilized in the kinetic resolution of phosphonates. Enantioselective acylation of a variety …

The Effect Of Active Site Mutations On The Homodimeric Behavior Of The Pvuii Restriction Endonuclease, Grigorios A. Papadakos

Dissertations

The PvuII restriction endonuclease, a homodimer of two 18 kDa subunits, belongs to the type II family of restriction enzymes. Located in the active site of PvuII, Tyrosine 94 has previously been shown to be involved in the metal ion binding by the enzyme. The profile of the Ca2+ dependence of the DNA binding to the Y94F variant is shown to be clearly biphasic. The application of a sequential binding model yielded a coupling energy (ΔGcoop) at -0.54 for the upper phase and -1.15 kcal/mole for the lower phase. The similar metal binding pattern between the Y94F and the WT …

Mechanistic Studies Of Specific Dna Cleavage By Pvuii Restriction Endonuclease, Xie Fuqian

Dissertations

PvuII restriction endonuclease is a homodimeric protein which recognizes and cleaves the palindromic sequence (CAG?CTG) in the presence of Mg(II) ions. Starting with PvuII as a model system, pKa calculations with crystallographically defined metal ligated water are applied to PD?D/ExK motif metallonucleases in order to investigate the activation of nucleophile in metal dependent DNA hydrolysis. These results establish the electrostatic contributions of the metal ions and the conserved Lys in lowering water pKa. The calculated pKa values of metal ligands have been used to simulate the pH dependence of Mg(II) binding to PvuII. The bell shaped pH-rate profile is dissected …

Synthesis, Characterization, And Catalytic Application Of Gold Nanoparticles, Junhyung Kim

Dissertations

Properties of nanometer-sized gold(Au) particles, especially those that are protected by a monolayer coating of thiolate ligands, called 'Monolayer Protected Clusters' (MPCs), are of rigorous multidisciplinary interest for their potential applications in catalysis and electronics due to their variation with size.

In larger core diameter sizes (>1.5nm) AuMPCs show metallic behavior as observed from electrochemical measurements. On the other hand, sub-nanometer ([approximate]1.1nm) AuMPCs exhibit molecule-like electronic behavior which is typical of Au38 nanoparticles. The various alkane chain thiols(C4 S-C12 S) capped Au38 MPCs have been examined with independent analytical tools, producing a remarkably consistent picture of these materials.

The …

Exploration Of The Chemical And Biological Processes Through Molecular Dynamics Simulation And Blocklocalized Wavefunction Method, Yuchun Lin

Dissertations

Computer simulation plays a crucial role in interpreting, unifying and guiding experimental observations. In this dissertation, molecular dynamics (MD) simulations and the block-localized wavefunction (BLW) method have been used to explore the chemical and biological processes.

Detailed MD simulations were performed to study the transportation of NH₄⁺, NH₃ and H₂O through the Escherichia coli ammonium transporter (AmtB) membrane protein. A periplasmic recruitment vestibule was identified and the entrance of an NH₄⁺ into this vestibule requires only 3.1 kcal/mol. In the end of this vestibule, the phenyl ring of Phe107 dynamically opens and …

Remote Sensing Solutions For Estimating Runoff And Recharge In Arid Environments, Adam M. Milewski

Dissertations

Efforts to understand and to quantify the interplay between precipitation, runoff, and recharge are often hampered by the paucity of appropriate monitoring systems. We developed methodologies for rainfall-runoff and groundwater recharge computations that heavily rely on observations extracted from a wide-range of global remote sensing data sets (TRMM, SSM/I, AVHRR, and AMSR-E,) using the arid Sinai Peninsula (SP; area: 61,000 km²) and the Eastern Desert (ED; area: 220,000 km²) of Egypt as our test sites. A two-fold exercise was conducted. Temporal remote sensing data (TRMM, AVHRR and AMSR-E) were extracted from global data sets over the …

The Role Of Short Term Synamptic Plasticity In Temporal Coding Of Neuronal Networks, Lakshmi Chandrasekaran

Dissertations

Short term synaptic plasticity is a phenomenon which is commonly found in the central nervous system. It could contribute to functions of signal processing namely, temporal integration and coincidence detection by modulating the input synaptic strength. This dissertation has two parts. First we study the effects of short term synaptic plasticity in enhancing coincidence detecting ability of neurons in the avian auditory brainstem. Coincidence detection means a target neuron has a higher firing rate when it receives simultaneous inputs from different neurons as opposed to inputs with large phase delays. This property is used by birds in sound localization. When …

Projecting Land Use Changes Using Parcel-Level Data : Model Development And Application To Hunterdon County, New Jersey, Florencio C. Ballesteros Jr.

Dissertations

This dissertation is to develop a parcel-based spatial land use change prediction model by coupling various machine learning and interpretation algorithms such as cellular automata (CA) and decision tree (DT). CA is a collection of cells that evolves through a number of discrete time steps according to a set of transition rules based on the state of each cell and the characteristics of its neighboring cells. DT is a data mining and machine learning tool that extracts the patterns of decision process from observed cell behaviors and their affecting factors. In this dissertation, CA is used to predict the future …

Roles Of Gap Junctions In Neuronal Networks, Joon Ha

Dissertations

This dissertation studies the roles of gap junctions in the dynamics of neuronal networks in three distinct problems. First, we study the circumstances under which a network of excitable cells coupled by gap junctions exhibits sustained activity. We investigate how network connectivity and refractory length affect the sustainment of activity in an abstract network. Second, we build a mathematical model for gap junctionally coupled cables to understand the voltage response along the cables as a function of cable diameter. For the coupled cables, as cable diameter increases, the electrotonic distance decreases, which cause the voltage to attenuate less, but the …

Synthesis And Characterization Of Plasma Enhanced Chemically Vapor Deposited Tantalum Films, Weizhong Chen

Dissertations

A low temperature inorganic plasma-enhanced chemical vapor deposition (PECVD) process has been developed for the growth of Ta using tantalum pentachloride (TaC15) as the preferred precursor and hydrogen as the reactant gas. Ta coatings were deposited at substrate temperature of 370-400 °C, reactor working pressures of 0.7-2 Ton, hydrogen carrier flow rate of 10-20 sccm, hydrogen reactant flow rates of 500 sccm, and plasma power ranging from 60 to 100W. Ta coatings were characterized with respect to their chemical, structural, and morphological properties by Auger electron spectroscopy (AES), x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), scanning …

Appropriation Of Privacy Management Within Social Networking Sites, Catherine Dwyer

Dissertations

Social networking sites have emerged as one of the most widely used types of interactive systems, with memberships numbering in the hundreds of millions around the globe. By providing tools for their members to manage an ever-changing set of relationships, social networking sites push a constant expansion of social boundaries. These sites place less emphasis on tools that limit social boundaries to enable privacy.

The rapid expansion of online social boundaries has caused privacy shockwaves. Privacy offline is enabled by constraints of time and space. Online, powerful search engines and long term digital storage means private data have no expiration …

Instabilities Of Volatile Films And Drops, Nebojsa Murisic

Dissertations

We report on instabilities during spreading of volatile liquids, with emphasis on the novel instability observed when isopropyl alcohol (IPA) is deposited on a monocrystalline silicon (Si) wafer. This instability is characterized by emission of drops ahead of the expanding front, with each drop followed by smaller, satellite droplets, forming the structures which we nickname “octopi” due to their appearance. A less volatile liquid, or a substrate of larger heat conductivity, suppress this instability. In addition, we examine the spreading of drops of water (DJW)-JPA mixtures on both Si wafers and plain glass slides, and describe the variety of contact …

Signal Transmission In Epithelial Layers, Filippo Posta

Dissertations

Cell signaling is at the basis of many biological processes such as development, tissue repair, and homeostasis. It can be carried out by different mechanisms. Here we are focusing on ligand mediated cell-to-cell signaling in which a molecule (ligand) is free to move into the extra-cellular medium. On the cell layer surface, it can bind to its molecule-specific receptors located on the cell plasma membrane. This mechanism is the subject of many experimental and theoretical studies on many model biological systems, such as the follicular epithelium of the Drosophila egg, which motivates this work.

Here, we present a general mathematical …

Data Allocation In Disk Arrays With Multiple Raid Levels, Jun Xu

Dissertations

There has been an explosion in the amount of generated data, which has to be stored reliably because it is not easily reproducible. Some datasets require frequent read and write access. like online transaction processing applications. Others just need to be stored safely and read once in a while, as in data mining. This different access requirements can be solved by using the RAID (redundant array of inexpensive disks) paradigm. i.e., RAIDi for the first situation and RAID5 for the second situation. Furthermore rather than providing two disk arrays with RAID 1 and RAID5 capabilities, a controller can be postulated …

The Impact Of Cultural Differences In Temporal Perception On Global Software Development Teams, Richard William Egan

Dissertations

This dissertation investigated the impact of cultural differences in temporal perception on globally dispersed software development teams. Literature and anecdotal evidence suggest that these temporal differences affect individual communication quality, which in turn will affect individual satisfaction and trust within global teams. Additionally, the temporal dispersion of the team was expected to affect an individual's sense of temporal disruption which, in turn, was expected to affect individual satisfaction and trust. Differences in temporal perception were expected to moderate this impact on perceived temporal disruption. A Fortune 100 Company that carried out software testing in Ireland, the United States, China and …

Dynamics Of Online Chat, Mihai Moldovan

Dissertations

Millions of people use online synchronous chat networks on a daily basis for work, play and education. Despite their widespread use, little is known about their user dynamics. For example, one does not know how many users are typically co-present and actively engaged in public interaction in the individual chat rooms of any of the numerous public Internet Relay Chat (IRC) networks found on the Internet; or what are the factors that constrain the boundaries of user activity inside those chat rooms. Failure to collect and present such data means there is a lack of a good understanding of the …

Perception Gaps And The Adoption Of Information Technology In The Clinical Healthcare Environment, Karen Hare

Dissertations

Implementation of information systems has lagged in many areas of clinical healthcare for a variety of reasons. Economics, data complexity and resistance are among the often quoted roadblocks. Research suggests that physicians play a major part in the adoption, use and diffusion of information technology (IT) in clinical settings. There are also other healthcare professionals, clinical and non-clinical, who play important roles in making decisions about the acquisition of information technology. In addition to these groups there are information technology professionals providing the services required within the healthcare field. Finally within this group are those IT professionals who have sufficient …

Broadband Dielectric Spectroscopy Studies Of Nafion, David Walter Rhoades

Dissertations

In light of available literature regarding Nafion® materials, it is apparent that an information gap exists between the current state of understanding of Nafion relaxations and the dielectric behavior of these materials. Although the currently available dielectric relaxation data is accurate it is very limited in its scope—specifically in-depth broadband analyses are not available. As a result, very little information is available regarding the dependence of the relaxation processes on frequency and temperature. This presents an important opportunity for the exploration of the dielectric broadband relaxation behavior of Nafion® materials. The primary intent of this research is to quantify the …

Photopolymerization And Characterization Of Crosslinked Thiol-Ene Networks And Poss/Thiol-Ene Nanocomposites, Tolecia Sharonda Shaunee Clark

Dissertations

Interests in the area of thiol-ene photopolymerization are rapidly expanding due to the numerous advantages over the polymers produced by traditional solvent based polymerizations. Although current research of photoinitiated thiol-ene polymerization is diverse, numerous opportunities are available for investigating structure/property and structure/reactivity relationships and novel material applications. This research in this dissertation includes a fundamental study of the effect of monomelic thiol functionality on thiol-ene polymerization kinetics and formation of the thiol-ene network structure, and an investigation of the development of novel silicate based thiol-ene nanocomposites. The first fundamental study investigates the effect of thiol functionality on the kinetics and …

The Design, Synthesis, And Controlled Polymerization Of Cationic And Zwitterionic Norbornene Derivatives, David Allen Rankin

Dissertations

Ring-opening metathesis polymerization (ROMP) has been exploited for the controlled polymerization of cationic and zwitterionic norbornene-based monomers and employed in the preparation of homo- and block-copolymer systems in homogeneous organic media without the use of post-polymerization modification or protecting group chemistries. Relying on previous knowledge of certain halogenated alcoholic organic solvents capable of solubilizing hydrophilic monomers, the first study, describes the synthesis and controlled polymerization of a series of new permanently cationic ammonium exo-7- oxanorbornene derivatives M31 via ROMP, with the first generation Grubbs catalyst 17, in a novel solvent mixture comprised of 1:1 vol/vol 2,2,2-trifluoroethanol (TFE)/methylene chloride (CH2CI2). This …