Physical Sciences and Mathematics Commons^™

Single Molecule Electrophoresis And Optical Detection Using Thermoplastic Nanofluidic Devices: An Experimental And Simulation Study, Kumuditha Madushanka Weerakoon Ratnayake

LSU Doctoral Dissertations

Nanofludic devices provide a great platform for single molecular analysis. The unique phenomena in nanoscale gained such interest in investigating the single molecular behavior in nanochannels. Sizes less than 200 nm in one or two-dimensional structures have lead to fascinating observations not accessible in microscale. When a single molecule translocates through a nanotube it interacts with channel walls by adsorption/ desorption, van der Waals interactions and hydrophilic interactions providing a mechanism for separation without any extra additives. Moreover, double layer thickness governed by the background electrolyte plays a vital role. We report single molecular electrophoresis phenomena in nanochannels and nanoslits …

Development Of Transition Metal-Catalyzed Polymerization Reactions And Their Applications For The Preparation Of Well-Defined Conjugated Polymer Architectures, Carlos Anthony Chavez

LSU Doctoral Dissertations

The synthesis of conjugated polymers and design of complex materials based on them have become increasingly popular as the demand for low-cost efficient and processible optoelectronic and semiconducting devices escalates. While advanced applications of polymeric materials require some degree of sophistication, success can be achieved through careful consideration of polymerization techniques and methodologies. Controlling critical aspects of the polymerization process allows for synthesis of complex macromolecular architectures possessing unique and novel properties that may be worth of further comprehensive investigation. This dissertation primarily focuses on the development and preparation of well-defined hierarchical macromolecular architectures. The foundation of this work encompasses …

Pattern Mining And Events Discovery In Molecular Dynamics Simulations Data, Shobhit Sandesh Shakya

LSU Doctoral Dissertations

Molecular dynamics simulation method is widely used to calculate and understand a wide range of properties of materials. A lot of research efforts have been focused on simulation techniques but relatively fewer works are done on methods for analyzing the simulation results. Large-scale simulations usually generate massive amounts of data, which make manual analysis infeasible, particularly when it is necessary to look into the details of the simulation results. In this dissertation, we propose a system that uses computational method to automatically perform analysis of simulation data, which represent atomic position-time series. The system identifies, in an automated fashion, the …

Exploring Superconductivity In Chiral Structured Aube, Drew Jared Rebar

LSU Doctoral Dissertations

AuBe is a noncentrosymmetric superconductor with the B20 FeSi-type structure. Noncentrosymmetric superconductors are expected to give rise to unconventional superconductivity due to spin orbit coupling and a mixed spin-singlet, spin-triplet state. The B20 structure of AuBe is particularly interesting since this is one of the only known crystal structures for bulk magnetic skyrmions in materials such as MnSi and Cu2OSeO3. The superconducting state was characterized by specific heat, dc magnetization, ac susceptibility, and resistivity. Specific heat revealed AuBe to host an isotropic gap characteristic of predominantly s-wave spin-singlet pairing in the weak coupling limit. Magnetization and susceptibility measurements revealed a …

Magnetic Susceptibility Of North American Ordovician Epicontinental Seas: Spatial Variability And Sandbian-Katian Boundary Correlation, Thomas J. Schramm

LSU Doctoral Dissertations

Magnetic susceptibility (χ) has gained increased usage as a stratigraphic correlation tool. This project evaluates the utility of a χ correlation tool, including its shortcomings, and attempts its integration with other datasets. The Upper Ordovician of eastern North America represent the stratigraphic interval in which these experiments were conducted. 4566 samples were collected for the purposes of this study, and χ was measured on 3345 of the samples. This project includes three major facets, 1) the spatial variability of χ, 2) correlation of Sandbian-Katian boundary interval strata in eastern North America using χ, and 3) utility of χ for interpreting …

Seismic Velocity Characteristics Of Partially Saturated Unconsolidated Sediments, Jie Shen

LSU Doctoral Dissertations

Seismic velocity models of the near-surface (< 30 m) better explain seismic velocities when all elements of total effective stress are considered, particularly in materials with large cohesive and soil suction stress such as clays. Traditional constitutive elastic models assume interparticle and soil suction stresses are negligible. This study proposes a new methodology which corrects total effective stress in Hertz-Mindlin theory for interparticle and soil suction and calculates the elastic moduli by extending Biot-Gassmann theory to include pressure effects induced by water saturation changes and cohesion. The proposed model predicts seismic velocities that correlate well with measured field velocities from the literature. Soil density, porosity, elastic moduli and the soil-water characteristic curve (SWCC) are important properties for soil characterization. Currently, geotechnical and laboratory tests for soil properties are costly and limited to point sampling sites. Seismic surveys can potentially provide laterally continuous soil property values that may complement geotechnical borehole tests with low cost. We propose a new method to invert for soil properties and the SWCC from seismic P- and S-wave velocity-vs.-depth profiles interpreted from shallow (< 25 m depth) unconsolidated sediments under conditions of near-full saturation (> 99%). The results from seismic soil property inversion are validated by comparison to geotechnical and laboratory results conducted independently in the same area as the seismic survey. Knowledge of homogeneous and heterogeneous fluid-distribution patterns is important for the estimation of oil reserves, reservoir simulation, the interpretation of time-lapse seismic, and the selection of remediation techniques for groundwater contamination. Problems exist in determining in-situ fluid-distribution patterns in unconsolidated sediments because laboratory tests on core samples may not be representative of in-situ conditions. We propose a new method to determine in-situ fluid-distribution patterns by inverting …

Development Of New Linking Chemistry With The Fac-{Re(Co)3}+ Core For Eventual Applications In Radiopharmaceuticals In Imaging And Therapy, Aponsu Meregngna Pramuditha Lakmi Abhayawardhana

LSU Doctoral Dissertations

The facile labeling of biomolecules with a radionuclide is a key goal in radiopharmaceutical development. This study explores two different ligand systems for fac-[Re(CO)3L]+ complexes, that could be used in bioconjugation. The first approach uses a tridentate ligand having a sulfonamide linkage and modeled on previously evaluated fac-[Re(CO)3(N(SO2R)dpa)]PF6 complexes. The present goal was to develop new related sulfonamide complexes with more hydrophilic ligands designed to avoid the bioavailability problems that would plague the N(SO2R)dpa ligand system. A series of fac-[Re(CO)3(N(SO2R)dien)]PF6 complexes with different R groups linked to the central nitrogen of a symmetric tridentate sulfonamides were synthesized with the aim …

Boron Functionalization Of Bodipy Dyes, And Their Evaluation As Bioimaging Agents, Alex Long Nguyen

LSU Doctoral Dissertations

BODIPY, also known as “porphyrin’s little sister,” belongs to a class of fluorescent dyes. It contains a dipyrromethene π-system with a disubstituted boron atom. The basic 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is known for its numerous useful applications in the fields of biology and materials. Modification of this well-known fluorophore has been shown to change its photophysical and chemical properties. There has been great interest in the modification at the boron center in recent years for synthesizing new dyads and cascade-type dyes. This work focuses on functionalization at the boron center with carbon and oxygen nucleophiles for further investigation as bioimaging agents. Chapter …

Design And Validation Of A Prototype Collimation System With Reduced Applicator Weights For Elekta Electron Therapy Beams, Garrett Michael Pitcher

LSU Doctoral Dissertations

The objective of this study was to design an electron collimation system for Elekta Infinity accelerators with significantly reduced applicator weights, while maintaining acceptable in-field beam flatness and out-of-field leakage dose. The design was restricted to 6-20 MeV beams for 6x6 to 25x25 cm2 applicators at 100 cm SSD with the MLCi2 treatment head. In Aim1, measured off-axis profiles showed that the current Elekta collimation system met dose flatness (4%) and IEC leakage dose specifications in the patient plane for custom 7, 13, and 20 MeV beams at MBPCC. Also, Monte Carlo (MC) calculations based on MBPCC beam models sufficiently …

Classification In The Presence Of Ordered Classes And Weighted Evaluative Attributes, Forrest Justin Osterman

LSU Doctoral Dissertations

We are interested in an important family of problems in the interface of the Multi-Attribute Decision-Making and Data Mining fields. This is a special case of the general classification problem, in which records describing entities of interest have been expressed in terms of a number of evaluative attributes. These attributes are associated with weights of importance, and both the data and the classes are ordinal. Our goal is to use historical records and the corresponding decisions to best estimate the class values of new data points in a way consistent with prior classification decisions, without knowledge of the weights of …

Excluding Two Minors Of The Petersen Graph, Adam Beau Ferguson

LSU Doctoral Dissertations

In this dissertation, we begin with a brief survey of the Petersen graph and its role in graph theory. We will then develop an alternative decomposition to clique sums for 3-connected graphs, called T-sums. This decomposition will be used in Chapter 2 to completely characterize those graphs which have no P_3 minor, where P_3 is a graph with 7 vertices, 12 edges, and is isomorphic to the graph created by contracting three edges of a perfect matching of the Petersen Graph. In Chapter 3, we determine the structure of any large internally 4-connected graph which has no P_2 minor, where …

Knots, Skein Theory And Q-Series, Mustafa Hajij

LSU Doctoral Dissertations

The tail of a sequence {P_n(q)} of formal power series in Z[q^{-1}][[q]], if it exists, is the formal power series whose first $n$ coefficients agree up to a common sign with the first n coefficients of P_n. The colored Jones polynomial is link invariant that associates to every link in S^3 a sequence of Laurent polynomials. In the first part of this work we study the tail of the unreduced colored Jones polynomial of alternating links using the colored Kauffman skein relation. This gives a natural extension of a result by Kauffman, Murasugi, and Thistlethwaite regarding the highest and lowest …

I. Synthesis Of Ascarosides For Chemical Biology Studies In Caenorhabditis Elegans, Ii. A Photochemical Approach To Delavayine, And Iii. Remote Hydroxylation By Radical Translocation And Polar Crossover, Kyle Allen Hollister

LSU Doctoral Dissertations

The foci of this dissertation are the synthesis of analogs for chemical biology studies, synthetic chemistry method development (with an emphasis on photochemistry), and the application of these methods toward total synthesis. Chapter 1 outlines the synthesis of an array of pheromone analogs that are derivatives of the dideoxy sugar ascarylose. Referred to as ascarosides, such compounds have recently been shown to influence important biological processes in the model organism Caenorhabditis elegans. C. elegans secretes ascarosides into its environment, where the compounds then act as signaling molecules by providing information on factors like population density. Chapter 2 describes the biological …

Analysis Of Nonlinear Dispersive Model Equations, Jacob Grey

LSU Doctoral Dissertations

In this work we begin with a brief survey of the classical fluid dynamics problem of water waves, and then proceed to derive well known evolution equations via a Hamiltonian Variational approach. This method was first introduced in the seminal work of Walter Craig, et al. \cite{CG}. The distinguishing feature of this scheme is that the Dirichlet-Neumann operator of the fluid domain appears explicitly in the Hamiltonian. In the second and third chapters, we utilize the Hamiltonian perturbation theory introduced in \cite{CG} to derive the Benjamin-Bona-Mahony (BBM) and Benjamin-Bona-Mahony-Kadomtsev-Petviashvili (BBM-KP)equations. Finally, we briefly review the existence theory for their corresponding …

Rényi Quantum Conditional Mutual Information And Parity Quantum Optical Metrology, Kaushik Parasuram Seshadreesan

LSU Doctoral Dissertations

This is a two-part thesis strung together by a common underlying theme—quantum correlations. We present some new characterizations and quantifications of quantum correlations and an application of one such correlation—entanglement—for quantum technology.

In Part I of the thesis, we use a Rényi generalization of the quantum conditional mutual information (QCMI) to define and study new measures of quantum entanglement and quantum discord. In particular, using a quantity derived from a Rényi QCMI, we introduce: a) the geometric squashed entanglement, a faithful entanglement measure, which is a lower bound on the squashed entanglement and which reduces to the geometric measure of …

Towards The Realization Of Systematic, Self-Consistent Typical Medium Theory For Interacting Disordered Systems, Chinedu Ekuma Ekuma

LSU Doctoral Dissertations

This work is devoted to the development of a systematic method for studying electron localization. The developed method is Typical Medium Dynamical Cluster Approximation (TMDCA) using the Anderson-Hubbard model. The TMDCA incorporates non-local correlations beyond the local typical environment in a self-consistent way utilizing the momentum resolved typical-density-of-states and the non-local hybridization function to characterize the localization transition. For the (non-interacting) Anderson model, I show that the TMDCA provides a proper description of the Anderson localization transition in one, two, and three dimensions. In three-dimensions, as a function of cluster size, the TMDCA systematically recovers the re-entrance behavior of the …

Left-Orderability, Cyclic Branched Covers And Representations Of The Knot Group, Ying Hu

LSU Doctoral Dissertations

A group G is called left-orderable if one can find a total order on G, which is preserved under left multiplication. In this paper we first give a sufficient condition for the fundamental group of the nth cyclic branched cover of the three sphere over a prime knot K to be left-orderable, in terms of representations of the knot group. Then we make use of this criterion to study the left-orderability of fundamental groups of cyclic branched covers over two-bridge knots and satellite knots.

Using Trace Fossils To Determine The Role Of Oceanic Anoxic Event Ii On The Cretaceous Western Interior Seaway Paleoenvironment, Jacob Frederick Grosskopf

LSU Doctoral Dissertations

Did well-oxygenated benthic conditions exist in all parts of the Cretaceous Western Interior Seaway (CWIS) during the deposition of Bed 63 at the onset Oceanic Anoxic Event II (OAE II), as suggested by findings from two cores from the central portion of the CWIS? This problem was approached by categorizing the bioturbation that is prevalent through Bed 63 into oxygen-related ichnofabrics (ORI) in order to describe benthic oxygen conditions. These data were collected from outcrop and core among seven different sites along West–East and North–South transects that traversed portions of the CWIS with differing depositional settings and proximities to the …

On The Development Of Analytical Methodologies To Interrogate The Lipid Dynamics And Phase Transition Resulting From The Reduction Of Stimuli-Responsive Vesicles, James Edward Winter

LSU Doctoral Dissertations

The potential is great for liposome drug delivery systems that provide specific contents release at diseased tissue sites upon activation by upregulated enzymes; however, this potential will only come to fruition with mechanistic knowledge of the contents release process. NAD(P)H:quinone oxidoreductase type 1 (NQO1) is a target for reductively-responsive liposomes, as it is an enzyme upregulated in numerous cancer tissues and is capable of reducing quinone propionic acid (QPA) trigger groups to hydroquinones that self-cleave from dioleolylphosphatidylethanolamine (DOPE) liposome surfaces, thereby initiating contents release. This research targets the development of analytical methodologies to observe and characterize the dynamics and resulting …

Photoelectrons And Recombining Electrons In Atomic And Molecular Systems, Kristen D'Ann Fulfer

LSU Doctoral Dissertations

This work in this dissertation explores how photoelectrons enter and exit atoms and molecules. The electron rescattering events which may occur during photoionization or photorecombination processes play a dominant role in the understanding of how photoelectrons enter and exit molecules, which is intrinsically linked to how chemical reactions occur. Chapters 3-4 of this dissertation present evidence of vibrational mode specific breakdown of the Franck-Condon Principle in the photoionization of low symmetry molecules, acrolein and the singly halogenated thiophenes, due to resonant and non-resonant electron rescattering dynamics. In Chapters 5-6, the disentanglement of the valence electronic structure, as well as evidence …

Nanoscale Gumbos: Size-Control, Characterization, And Applications As Enantioselective Molecularly Imprinted Polymers And Fluorescent Materials, Suzana Hamdan

LSU Doctoral Dissertations

Nanomaterials derived from a group of uniform materials based on organic salts (GUMBOS) have been introduced into the scientific literature through many analytical, biological, and technological applications. These nanomaterials, referred to as nanoGUMBOS, have been shown to display a number of interesting properties including fluorescence, magnetism, tumor targeting, and optoelectronic properties. Herein, we present major studies on nanoGUMBOS including synthesis and size-control, chiral molecular imprinting in polymers, as well as investigation of optical properties and quantum yield of fluorescent semiconductor-based nanoGUMBOS. Various strategies were introduced for production of well-defined nanoGUMBOS. Specifically, several methods based on sonochemistry, microwave, cyclodextrin, and surfactant-assisted …

Platinum Complexes With Tridentate Ligands As Models For Active Monofunctional Anticancer Drugs, Chase Koby Andrepont

LSU Doctoral Dissertations

Pt(II) complexes bind preferentially at N7 of G residues of DNA, causing DNA structural distortions associated with anticancer activity. Some distortions induced by difunctional cisplatin are also found for monofunctional Pt(II) complexes with carrier ligands having bulk projecting toward the guanine base. This ligand bulk can be correlated with impeded rotation about the Pt–N7(guanine) bond. The objective of this study is to understand the influences of in-plane bulk of Pt(Ltri)G adducts (Ltri = tridentate carrier ligand, G = guanine derivative bound to a metal, but not tethered to another nucleobase). NMR spectroscopy provided conclusive evidence that Pt(Ltri)G (Ltri = di-(2-picolyl)amine …

Gumbos As Matrices For Matrix-Assisted Laser Desorption Ionization Time Of Flight Mass Spectrometry, Hashim Abdullah Al Ghafly

LSU Doctoral Dissertations

This work involves the investigation of a group of uniform materials based on organic salts (GUMBOS) as matrices for matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF) for analysis of hydrophobic biomolecules. GUMBOS are new class of materials that show great promise as MALDI matrices because they are able to form a thin-layer on the MS target, thereby enhancing the sample homogeneity, signal intensity, and shot-to-shot reproducibility. The detection of hydrophobic peptides using MALDI-TOF MS remains a challenge because the majority of matrices utilized are hydrophilic thereby exhibiting low affinity for hydrophobic molecules. To address this, I …

Anisotropic Spacetimes And Black Hole Interiors In Loop Quantum Gravity, Anton Joe

LSU Doctoral Dissertations

This thesis deals with understanding quantum gravitational effects in those anisotropic spacetimes which serve as black hole interiors. Two types of spacetime are investigated. Kantowski-Sachs spacetime and Bianchi-III LRS spacetime. The former, in vacuum, is the interor spacetime for Schwarzschild black holes. The latter is the interior for higher genus black holes. These spacetimes are studied in the context of loop quantum cosmology. Using effective dynamics of loop quantum cosmology, the behavior of expansion and shear scalars in different proposed quantizations of the Kantowski-Sachs spacetime with matter is investigated. It is found that out of the various proposed choices, there …

Synthesis, Characterization, And Evaluation Of Small Molecule-Based Fluorogenic Probes For The Detection Of Cellular Thiols, Rasika Ranatunga Nawimanage

LSU Doctoral Dissertations

Fluorescence methods for disease diagnosis and detection of important analytes are becoming popular route as a technique, as they offer a simple non-invasive approach. Recently, many novel fluorophores and probes have been reported for selectively and sensitively detecting low abundance biological species in disease pathways. Biological thiols, such as glutathione, cysteine, and homocysteine, along with the smallest member hydrogen sulfide, are key thiol analytes in biological environments, and they play a vital role in living systems by maintaining the redox homeostasis of cells. Alteration of their ratios can cause cellular dysfunction and cell death. Furthermore, thiol levels in cells and …

Synthetic Methods Development Towards The Total Synthesis Of Chlorosulfolipids, Andres Villalpando

LSU Doctoral Dissertations

The focus of this dissertation is the development of a novel chlorination reaction utilizing a triphosgene-amine based mixture towards the total synthesis of chlorosulfolipids, a subclass of naturally occurring organohalogen natural products. This novel, mild chlorination reaction will be utilized under a global chlorination strategy to chlorinate multiple alcohol substituents in one synthetic operation. Chapter one details the history of chlorosulfolipids from the early stages of their isolation, relevant structural elucidation techniques, appropriate biosynthetic discoveries, and their biological relevance to a thorough investigation of the total syntheses completed to date. These compounds demonstrate a range of biological activities and have …

Polycyclic Aromatic Hydrocarbons Dynamics In The Northern Gulf Of Mexico, Puspa Lal Adhikari

LSU Doctoral Dissertations

Polycyclic aromatic hydrocarbons (PAHs) are introduced into the marine environment via oil seeps/spills, riverine discharges, continental runoff, coastal erosion, and atmospheric deposition. An estimated 2.1 x 1010g of PAHs entered into the northern Gulf of Mexico (GOM) during the Deepwater Horizon (DWH) oil spill in 2010. It became evident following the oil spill that accurate quantification of ultimate fate of these potentially carcinogenic and/or mutagenic organic pollutants is extremely challenging. In general, very little is known about PAHs fate, distribution and accumulation in the open ocean ecosystems. This study determines the upper ocean vertical fluxes and sedimentary PAHs accumulation rates …

Game Theoretic Analyses Of The United States-Canada Softwood Lumber Trade, Rajan Parajuli

LSU Doctoral Dissertations

The ongoing softwood lumber trade dispute between the United States (U.S.) and Canada is one of the most contentious and largest bilateral trade battles over the recent decades. The bilateral trade debate is mostly because of the different forestland ownership systems in the U.S. and Canada, and the alleged timber subsidies by provincial governments to Canadian lumber producers. The Softwood Lumber Agreement (SLA) 2006 between the U.S. and Canada is the latest transitory solution of this dispute, entailing Canada to impose mandatory export charges on its lumber shipments to the U.S. In order to understand this trade dispute from a …

Optimized Aperiodic Multilayer Structures For Absorbers And Thermal Emitters, Christopher H. Granier

LSU Doctoral Dissertations

In this dissertation, we begin with a brief introduction to nanophotonics. In particular, we will focus on the theory of computational electricity and magnetism, specifically, the method used for this research, the transfer-matrix method. We will also provide discussions of the principles which motivate the analysis of the multilayer structures: Planck's blackbody distribution, Kirchoff's law, and thermodynamics. Finally, we will provide a brief discussion of computer-based optimization algorithms, specifically NLOPT (a library which provides computational packages for nonlinear optimization) and genetic algorithms. This background information is necessary to understand discussions which occur in later chapters.

Chapter 2 will discuss multilayer …

Attosecond Transient Absorption In Gases And High Harmonic Generation In Solids, Mengxi Wu

LSU Doctoral Dissertations

We present a theoretical study of attosecond transient absorption in gases and high harmonic generation in solids. In this thesis, different features in the attosecond transient absorption laser-dressed spectrum are studied, including features near bright (dipole allowed) atomic states and features that appear approximately one or two laser photons away from the bright states due to the laser-induced coupling to dark (non-dipole allowed) states. The calculations are carried out using both numerical and analytic solutions to the time-dependent Schr\"odinger equation (TDSE). From these solutions, several models of time-dependent absorption and electron dynamics at the femtosecond time scale are presented. We …