Digital Commons Network^™

Nuclear Structure Of 26si And 32cl For Astrophysics, Liudmyla Afanasieva

LSU Doctoral Dissertations

We studied the nuclear structure of two isotopes, 26Si and 32Cl, important for understanding stellar explosions like novae and Type I X-ray bursts. The 31S(p,γ)32Cl reaction rate influences the enrichment of sulfur observed in some nova ejecta, but the uncertainty in the rate spans as much as an order of magnitude and arises from uncertainties in the properties of resonances corresponding to excited states in 32Cl. We populated states in 32Cl via the 10B(24Mg,2n)32Cl reaction using the Argonne Tandem-Linac Accelerator System (ATLAS), with a 75 MeV beam of 24Mg bombarding a 200 μg/cm2 10B target. Gamma rays emitted from recoiling …

Interpretation Of Geochemical Signatures From Modern Carbonate Springs To The Rock Record, Benjamin Maas

LSU Doctoral Dissertations

Despite the importance of carbonate aquifers as reservoirs of oil, of water, and of carbon dioxide, questions remain about the diagenetic processes that enhance porosity and permeability. Some of the questions are: 1) what are the water-rock interactions that control the geochemistry of spring waters; 2) are the geochemical signatures of saline-fresh water mixing zones preserved in the carbonate rock record; and 3) how much carbon dioxide outgases along spring runs? To address these questions, two field sites, one in Oklahoma (the site of an active saline-fresh water mixing zone) and the other in Colorado, the location of a former …

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 …

An Evaluation Of Close Reading For Fourth Grade Students Receiving Tier 2 Responsiveness To Intervention Services, Marcy Boudreaux-Johnson

LSU Doctoral Dissertations

The primary purpose of the present study was to evaluate the effectiveness of a close reading instructional routine (also known as analytical reading decades ago) that has been described in the literature and promoted as a process to help students reading complex text independently and proficiently. A single subject alternating treatments design was implemented with six fourth grade students who had been identified as at risk for academic failure and were receiving supplemental, small-group instruction in their rural public school. The alternating treatments design allowed for a direct comparison of the close reading instructional routine and a validated reading comprehension …

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 …

The Agronomic Use And Application Of Canopy Reflectance Within The Visible And Near-Infrared Wavebands And Its Relation With Nitrogen Fertilization In Energy Cane Production In Louisiana, Saoli Chanda

LSU Doctoral Dissertations

Spectral vegetation index-based models that are used to estimate yield potential are commonly developed from the relationship between early-season crop canopy reflectance readings and actual yield obtained at harvest. Plant population stand can influence cane yield potential and nutrient requirement. This study was conducted at LSU AgCenter Sugar Research Station in St. Gabriel, LA to evaluate (1) the relation between estimated early season biomass yield and the spectral vegetation indices acquired at the same time, (2) nitrogen (N) response pattern between early-season biomass production and yield at harvest, and (3) the relationship between coefficient of variation (CV) among normalized difference …

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 …

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 …

L'Essentiel Ou Lagniappe: The Ideology Of French Revitalization In Louisiana, Albert Camp

LSU Doctoral Dissertations

Louisiana’s French revitalization movement has received millions of dollars in taxpayer funding through its various initiatives such as music and cultural festivals, public school French immersion programs, and academic exchange programs, among others. Over forty years ago, the state of Louisiana created CODOFIL, a government agency dedicated to the promotion of Francophone language and culture in Louisiana, yet the number of Francophones in the state has continued to decline at an alarming rate according to the most reliable data available. My study investigates the ideology and demographics of those involved in French education programs in Louisiana’s public schools. Who decides …

Probabilistic Performance-Based Hurricane Engineering (Pbhe) Framework, Vipin Unnithan Unnikrishnan

LSU Doctoral Dissertations

In modern times, hurricanes have caused enormous losses to the communities worldwide both in terms of property damage and loss of life. In light of these losses, a comprehensive methodology is required to improve the quantification of risk and the design of structures subject to hurricane hazard. This research develops a probabilistic Performance-Based Hurricane Engineering (PBHE) framework for hurricane risk assessment. The proposed PBHE is based on the total probability theorem, similar to the Performance-Based Earthquake Engineering (PBEE) framework developed by the Pacific Earthquake Engineering Research (PEER) Center, and to the Performance-Based Wind Engineering (PBWE) framework. The methodology presented in …

Spectrum Allocation In Networks With Finite Sources And Data-Driven Characterization Of Users' Stochastic Dynamics, Ahsan-Abbas Ali

LSU Doctoral Dissertations

During emergency situations, the public safety communication systems (PSCSs) get overloaded with high traffic loads. Note that these PSCSs are finite source networks. The goal of our study is to propose techniques for an efficient allocation of spectrum in finite source networks that can help alleviate the overloading of PSCSs. In a PSCS, there are two system segments, one for the system-access control and the other for communications, each having dedicated frequency channels. The first part of our research, consisting of three projects, is based on modeling and analysis of finite source systems for optimal spectrum allocation, for both access-control …

Costa Rican Composer Luis Diego Herra And His Symphony I An Annotated Edition, Norman Armando Gamboa

LSU Doctoral Dissertations

Luis Diego Herra (b. 1952) is regarded as one of the most important and versatile Costa Rican musicians of the present generation. A pioneer in the orchestral conducting arena, he was one of the first Central American conductors to pursue formal studies abroad. He served as professor of orchestral conducting and composition at the University of Costa Rica School of Music. Herra is a prolific composer, arranger, editor, and pedagogue, with an extensive output of more than 50 works. This research will focus on one of his most relevant compositions, the Symphony I of 1990, which marked a new chapter …

Chemically Patterned Surfaces As Test Platforms To Study Magnetic And Solvent-Responsive Properties At The Nanoscale: Investigations Using Scanning Probe Microscopy, Shalaka Kulkarni

LSU Doctoral Dissertations

Chemically patterned surfaces were fabricated using a combination of molecular self-assembly and particle lithography to generate billions of nanostructures of organosilane self-assembled monolayers (SAMs). Monodisperse mesospheres were used as surface masks to prepare nanostructures on flat surfaces using the simple benchtop chemistry steps of mixing, centrifuging, evaporation, and drying. Periodic arrays of well-defined organosilane nanostructures serve as discrete surface sites for the selective deposition of polymers and magnetic nanoparticles.

In this dissertation, particle lithography approaches for surface patterning provide new directions for studying surface chemistry at the molecular-level using high resolution investigations with scanning probe microscopy (SPM). Atomic force microscopy …

Application Of Discrete Element Method And Computational Fluid Dynamics To Selected Dispersed Phase Flow Problems, Oladapo Olanrewaju Ayeni

LSU Doctoral Dissertations

A parallel discrete particle modelling framework (PAR_DPM3D) is applied to study three fundamental multiphase flow problems: The sedimentation of a cluster of particles in a viscous ambient fluid, multiphase flow in a bench-scale fluidized bed and granular segregation and mixing dynamics in a rotating drum. Various phenomena including torus formation and particle cluster breakup are reproduced. We provide new insights into the volume fraction dependence of the dynamic characteristics of a settling particle cluster and find a similar dependence in the simulations as in the theoretical predictions of Nitsche and Batchelor 1. Similarities in the interaction between a system of …

Experimental Designs For Model Discrimination And Uncertainty Reduction In Groundwater Modeling, Hai Van Pham

LSU Doctoral Dissertations

Groundwater systems are complex and subject to multiple interpretations due to a lack of sufficient information. Different propositions (or alternatives) are often proposed to represent uncertain model components resulted in many conceptual models using the same data. Yet considering too many models may lead to high prediction uncertainty and may lose the purpose of model development. To decrease the prediction uncertainty due to conceptual model uncertainty, two experimental designs are proposed. The first experimental design intends to identify model propositions in each uncertain model component. A discrimination criterion is developed based on posterior model probability. Bayesian model averaging (BMA) is …

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.

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 …

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 …

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 …

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 …

Numerical Simulation Of Cold Front-Related Hydrodynamics Of Wax Lake Delta, Qian Zhang

LSU Doctoral Dissertations

This study applies a three-dimensional numerical model ECOM-si to simulate the circulation in the Wax Lake delta under winter cold front conditions. This model uses real topography and bathymetry of the area to reproduce tides and the circulation between December 2012 and January 2013, which captures a total of seven cold front passages. The model results demonstrate that the circulation in the Wax Lake delta area is significantly affected by the winter cold fronts. The major findings are: (1) Water fluxes in the delta distributary network are not solely propagated within the channels but also between the channels, indicating inundation …

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 …

Design And Application Of Task-Specific Organic Salts For Chemical And Biochemical Sensing, Waduge Indika Subodha Galpothdeniya

LSU Doctoral Dissertations

There is an increasing demand for development of new sensors and sensor strategies for accurate detection and discrimination of various analytes. In this regard, colorimetric and fluorometric sensor approaches have attracted considerable attention, primarily because they represent facile and inexpensive analytical tools. In this dissertation, I discuss the design and application of sensors and sensor arrays using task specific organic salts: ionic liquids (ILs) and a group of uniform materials based on organic salts (GUMBOS). As compared to typical ionic compounds, these two classes of organic salts exhibit relatively lower melting points due to bulky organic cations and/or anions. Interestingly, …

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 …

On The Thermally Induced Failure Of Rolling Element Bearings, Jafar Takabi

LSU Doctoral Dissertations

This dissertation is devoted to the investigation of thermally induced seizure of rolling element bearings. A comprehensive thermal model of the rolling element bearings is developed which can predict the operating temperature of the bearing components in a wide range of operating conditions. The validity of this thermal model is verified by comparing the simulation results with a set of experiments. The results of simulations reveal that the rotational speed, oil viscosity and cooling rate of the housing have a significant influence on the operating temperature of the rolling bearings. To provide detailed information about all of the contact forces …

Investigating Wave Forces On Coastal Bridge Decks, Guoji Xu

LSU Doctoral Dissertations

Tsunamis and hurricane induced waves are responsible for many coastal bridge failures, especially in the last decade. In the current study, three countermeasures (reducing the entrapped air, elevating the structures and rigidifying the structures) are considered, two wave types (solitary wave theory and Stokes wave theory) are chosen, and two bridge types (single bridge deck and twin bridge decks) are taken into account. Parametric studies are conducted based on Computational Fluid Dynamics (CFD) software ANSYS Fluent. This dissertation comprises two broad themes according to the wave types adopted. The first one is to make a great effort to investigate solitary …

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 …

Coupled Gradient Enhanced Damage - Viscoplasticity Model Using Phase Field Method, Navid Mozaffari

LSU Doctoral Dissertations

The aim of this dissertation is developing a framework to describe damage evolution as a phase transformation in solid materials and couple it to the well-known Perzyna type viscoplastic model to account for inelastic behavior of ductile materials. To accomplish this task, the following steps have been performed. First, a new nonlocal, gradient based damage model is proposed for isotropic elastic damage using the phase field method in order to show the evolution of damage in brittle materials. The general framework of the phase field model (PFM) is discussed and the order parameter is related to the damage variable in …

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 …