Physical Sciences and Mathematics Commons^™

Preparation And Characterization Of Cellulose Nanoparticles And Their Application In Biopolymeric Nanocomposites, Jingquan Han

LSU Doctoral Dissertations

Regenerated cellulose nanoparticles (RCNs) including both elongated fiber and spherical structures were prepared from microcrystalline cellulose (MCC) and cotton using 1-butyl-3-methylimidazolium chloride followed by high-pressure homogenization. The RCN has a two-step pyrolysis, different from raw MCC and cotton that had a one-step process. The crystalline structure of RCNs was cellulose II in contrast to the cellulose I form of the starting materials. Also, the RCNs have decreased crystallinity and crystallite size. The elongated RCNs produced from cotton and MCC had average lengths of 123 ± 34 and 112 ± 42 nm, and mean widths of 12 ± 5 and 12 …

Earth Occultation Imaging Of The Low Energy Gamma-Ray Sky With The Fermi/Gamma-Ray Burst Monitor, James Craig Rodi

LSU Doctoral Dissertations

The hard X-ray/soft gamma-ray sky is highly variable as source intensities can vary on timescales from fractions of a second to years. The type of sources emitting at these energies often include compact objects such as white dwarfs, neutron stars, and black holes interacting with the surrounding environment, which enables the study of the properties and characteristics of these exotic objects. Because the interactions with the environment is often through accretion, most of the emission is in X-rays and gamma-rays Frank et al. 1992 making this energy range critical to understanding the relevant physical processes and mechanisms. Hard X-ray/soft gamma-ray …

Depositional History Of The Trinity-Tiger Shoals Region : A Transgressed Delta Complex Of The Middle Holocene Mississippi Delta, Clint Hoyt Edrington

LSU Doctoral Dissertations

The Holocene Mississippi River Delta is arguably the world’s most thoroughly researched deltaic system. However, much of this research has occurred predominantly within the present-day subaerial delta, whereas comparatively little research has been attempted downdip within the offshore, more difficult-to-reach parts. This study advances our understanding of the Holocene delta by examining deltaic sediments within the Trinity-Tiger Shoals Complex region, located ~ 30 – 40 km offshore of central Louisiana. Specifically, this study addresses two questions. Which delta complex prograded into this offshore region? Do the overlying transgressive deposits reflect that predicted by the prevailing transgressive depositional systems model? To …

Higher Algebraic K-Theory And Tangent Spaces To Chow Groups, Sen Yang

LSU Doctoral Dissertations

In this work, using higher algebraic K-theory, we provide an answer to the following question asked by Green-Griffiths in [13]: Can one define the Bloch-Gersten-Quillen sequence G_j on infinitesimal neighborhoods X_j so that Ker(G₁ &rarr G₀)= TG₀, Here TG₀ should be the Cousin resolution of TK_m(O_X) and X is any n-dimensional smooth projective variety over a field k, chark=0. Our main results are as follows. The existence of G_j is discussed in chapter 3, following [8] and [18]. The main theorems are theorem5.2.5, theorem 5.2.6 and theorem …

Numerical Investigations Of Holstein Phonons On The Periodic Anderson Model, Peng Zhang

LSU Doctoral Dissertations

In condensed matter physics, the idea of localized magnetic moments and the scattering of conduction electrons by those local moments are of central importance not only for explaining the transport of electrons at low temperature region but also for developing the related models and theories to extend our understanding of novel physics like non-conventional superconductor, quantum phase transition and non-Fermi liquid behavior. In the first chapter of this work, I will look back at the discovery of Kondo scattering, the introduction of Anderson impurity scenario, the extension to lattice version of the Anderson impurities, the periodic Anderson model, and how …

On Identifying Critical Nuggets Of Information During Classification Task, David Sathiaraj

LSU Doctoral Dissertations

In large databases, there may exist critical nuggets - small collections of records or instances that contain domain-specific important information. This information can be used for future decision making such as labeling of critical, unlabeled data records and improving classification results by reducing false positive and false negative errors. In recent years, data mining efforts have focussed on pattern and outlier detection methods. However, not much effort has been dedicated to finding critical nuggets within a data set. This work introduces the idea of critical nuggets, proposes an innovative domain-independent method to measure criticality, suggests a heuristic to reduce the …

Patterns And Pathways Of Wetland Sedimentation And Landscape Change In Coastal Louisiana, Andrew William Tweel

LSU Doctoral Dissertations

Coastal Louisiana wetlands exist in a dynamic physical environment and retracted dramatically in the last century. Here I examine the spatial and temporal variability of this landscape with an emphasis on the interactions between anthropogenic landscape modifications and geological processes.

The Mississippi River watershed underwent drastic changes during the past 200 years, beginning with widespread land clearing and, later, large-scale reservoir construction. These modifications caused increases in suspended sediment concentrations, then sharp decreases, and have remained relatively stable since 1960. I show how changes in land area of the Mississippi River birdfoot delta reflect these fluctuations, and that they are …

Synthesis, Characterization And Biological Studies Of Carboranyl-Porphyrin Bioconjugates For Treatment Of Brain Tumors, Naga Venkata Satya Dinesh Kumar Bhupathiraju

LSU Doctoral Dissertations

Chapter 1 gives a brief introduction to brain tumors, approaches to deliver drug across the blood brain barrier (BBB), boron neutron capture therapy (BNCT) for brain tumors, application of carboranyl derivatives in attempt to treat brain tumors using BNCT. Chapter 2 involves synthesis, characterization and toxicity studies (In vitro and In vivo) of high boron containing pegylated cobaltabisdicarbollide porphyrin for treatment of brain tumors using BNCT. To improve the selectivity towards brain tumors we attempted conjugate several peptides to this non-toxic pegylated cobaltabiscabollide porphyrin. In vivo studies were conducted in collaboration with Dr. David G. Baker at LSU veterinary Medicine. …

Contractional Tectonics : The Himalayan Orogen And Perdido Fold-Thrust Belt, Dian He

LSU Doctoral Dissertations

This dissertation focuses on the kinematic evolution of two major categories of contractional tectonics: collisional orogenic belts and toe structures of passive margins, which are characterized by fold-thrust belts that are hundreds of kilometer-scale and tens of kilometer-scale, respectively. The Himalayan orogen is an excellent example of collisional orogenic belts along convergent plate boundaries. It is commonly structurally defined as three stacked units separated by two fault systems: the Main Central thrust (MCT) and South Tibet detachment (STD). The development and emplacement of the middle unit, the Himalayan crystalline core, has long been debated within the extrusion framework, a process …

Molecular Products From The Thermal Degradation Of Selected Tobacco Components: Lignin, Tyrosine, Glutamic Acid, And Modeling Of Lignin Pyrolysis Using Chemkin Combustion Suite, Joshua Kiprotich Kibet

LSU Doctoral Dissertations

This study explores the thermal decomposition behavior of selected tobacco components: lignin, tyrosine, and glutamic acid using the system for thermal diagnostic studies (STDS) in an in-line gas chromatography-mass spectrometer analytical technique. The pyrolysis conditions employed in this study were a flowing atmosphere of nitrogen and 4% O2 in nitrogen at a residence time of 0.2 seconds for a total pyrolysis time of 3 minutes. The results identified common relationships between the two modes of reaction atmospheres, as well as some differences. While some products were favored by an inert regime, some were favored under an oxidative regime. Oxidative pyrolysis …

Application Of Helmholtz/Hodge Decomposition To Finite Element Methods For Two-Dimensional Maxwell's Equations, Zhe Nan

LSU Doctoral Dissertations

In this work we apply the two-dimensional Helmholtz/Hodge decomposition to develop new finite element schemes for two-dimensional Maxwell's equations. We begin with the introduction of Maxwell's equations and a brief survey of finite element methods for Maxwell's equations. Then we review the related fundamentals in Chapter 2. In Chapter 3, we discuss the related vector function spaces and the Helmholtz/Hodge decomposition which are used in Chapter 4 and 5. The new results in this dissertation are presented in Chapter 4 and Chapter 5. In Chapter 4, we propose a new numerical approach for two-dimensional Maxwell's equations that is based on …

Fluorescent Materials For Chemical Sensing, Brian Gerard Imsick

LSU Doctoral Dissertations

Materials incorporating fluorescent π-electron conjugated molecular species for sensing and imaging are advantageous over other detection or identification methods such as colorimetric reporters. Fluorescent materials offer easy recognition of binding events due to the highly sensitive nature of fluorescence techniques down to the single molecule level. The properties of fluorescent molecules allow for rapid attenuation of observable readout due to the facile transport of excited state energy via both inter- and intramolecular pathways. This dissertation primarily focused on the development and study of a general platform for ratiometric fluorescent chemosensing using surface-immobilized oligomers, as well as in depth explorations of …

Oligomers Of Beta-L-Arabinosides Of Hydroxyproline : Synthesis Of The Carbohydrate Epitope Of The Art V 1 Allergen, Ning Xie

LSU Doctoral Dissertations

The pollen of mugwort is a major contributor to hay fever in Europe and North America. The chemical structure of Art v 1, the major allergen of mugwort, has been elucidated. A notable motif in Art v 1 – characterized by clusters of contiguous â-arabinosides of hydroxyproline – was found to be a key recognition element for antibodies generated in response to the natural protein. This dissertation details the chemical synthesis of oligomers of â-arabinosides of hydroxyproline and the search to establish the minimal carbohydrate epitope of Art v 1. The â-arabinoside motif, being a 1,2-cis glycoside, presents a considerable …

Oligohaline Wetland Response And Recovery Following Storm-Driven Saltwater Intrusion In Coastal Louisiana, Whitney Marie Kiehn

LSU Doctoral Dissertations

Coastal ecosystems occupy an interface between land and ocean, making them vulnerable to a variety of natural and anthropogenic disturbances. Large, episodic disturbances (mega-disturbances) cause immediate and long-lasting changes to coastal wetland plant communities and soils by changing the environmental conditions in which they exist. Here I examined the impacts of storm-induced saltwater intrusion and post-intrusion conditions on the structure and growth of an oligohaline wetland plant community, and on wetland soil biogeochemistry and conditions during and after saltwater intrusion. In the greenhouse, a six-week saltwater intrusion reduced canopy cover and species richness. Once intrusion stress was alleviated, plant community …

Design, Synthesis, And Characterization Of Porphyrin Derivatives For Biological Applications, Raja Gabadage Waruna Eranga Jinadasa

LSU Doctoral Dissertations

Chapter 1 of this Dissertation presents a brief introduction to the basic properties of porphyrins and their derivatives (hydroporphyrins), their abundance and functions in the nature, and their applications in photodynamic therapy. Chapter 2 reports the synthesis, characterization, conformational analysis and cellular studies of novel mono conjugated regioisomers of chlorin e₆ derivatives that are promising photosensitizers for photodynamic therapy. All three regioisomers were synthesized from pheophytin a, which was extracted from the alga Spirulina pacifica. In vitro investigations using human carcinoma HEp2 cells show that the 15²-lysyl regioisomers accumulate the most within cells, and the most phototoxic …

A Study Of The Temporal And Spatial Distribution Of Ichthyoplankton And Post-Larval Penaeids Recruiting Into A Louisiana Tidal Pass, Matthew John Kupchik

LSU Doctoral Dissertations

This dissertation attempts to better understand astronomical, meteorological, and oceanographic forcing of offshore-spawned, estuarine-dependent species from continental shelf to estuarine waters through tidal passes. The vertical distribution of zoo-/ichthyoplankton within the inner continental shelf from the Louisiana Offshore Oil Platform monitoring project (1978-1995) provided an important offshore end member for the estuarine recruitment study, and is potentially useful in predicting vulnerabilities to past and future oil spills. The role that atmospheric cold front passages may have on densities and movement of zoo-/ichthyoplankton recruiting through the Bayou Tartellan tidal pass, Louisiana, were analyzed using a Generalized Additive Model. The pre-frontal phase, …

Silica Polypeptide-Based Colloids: Physical Properties And Novel Materials, Cornelia Rosu

LSU Doctoral Dissertations

The investigation of polypeptide composite particles, PCPs, is described. The production of mesoporous and polycolloid architectures is also addressed. PCPs were prepared by both growing form and grafting to method. They consist of a core made of silica, silica-coated magnetite or silica-coated cobalt. Some of the particles were covalently labeled with fluorescein isothiocyanate. Several polypeptides were chosen for attachment on the core: poly(γ-stearyl-L-glutamate), PSLG, poly(Nε-carbobenzyloxy-L-lysine), PCBL and poly(o-benzyl-L-tyrosine), PBTY. Attachment of a well-characterized alkyne-end terminated PSLG and PCBL to an azide- functionalized particle yielded PCPs with a desired sparse coverage. A blend of techniques such as FTIR, XPS, TEM, HTEM, …

Surface Studies Of Organic Thin Films Using Scanning Probe Microscopy And Nanofabrication, Venetia Denae Lyles

LSU Doctoral Dissertations

Porphyrins and metalloporphyrins have unique chemical and electronic properties and thus provide useful model structures for nanoscale studies of the role of chemical structure for electronic properties. Porphyrins have been proposed as viable materials for molecular-based information-storage devices, gas sensors, photovoltaic cells, organic light-emitting diodes and molecular wires. The function and efficiency of porphyrins in devices is largely attributable to molecular architecture and how the molecules are self-organized. Modifications of the porphyrin macrocycle, peripheral groups or bound metal ions can generate a range of electrical, photoelectrical or magnetic properties. The conductive properties are greatly influenced at the molecular level by …

Single-Crystal Metal Oxides And Supported Metal Nanoclusters As Model Catalyst Sytems, Matthew C. Patterson

LSU Doctoral Dissertations

We have investigated the morphology and electronic structure of two basic classes of systems: metal oxide surfaces that catalyze the formation of environmentally persistent free radicals (EPFRs) from aromatic precursors, and Au and Cu nanoparticles that may be suitable catalysts for the catalytic oxidation of CO or hydrogenation of CO2. First, we examine the adsorption behavior of phenol on rutile TiO2(110) and ultrathin films of alumina prepared on a NiAl(110) substrate. Electron paramagnetic resonance studies show that exposure of both γ-alumina and titania powder to phenol at 250°C results in the formation of persistent phenoxyl radicals. EELS studies of phenol …