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Articles 1 - 30 of 50
Full-Text Articles in Physical Sciences and Mathematics
Investigation Of Antimonide Structure Types And The Structural Studies Of Molybdates, Dixie Plaisance Gautreaux
Investigation Of Antimonide Structure Types And The Structural Studies Of Molybdates, Dixie Plaisance Gautreaux
LSU Doctoral Dissertations
This dissertation highlights the investigation of ternary lanthanide antimonide structure types and their physical properties. In particular, these ternary phases allow for the systematic investigation of the structure in an effort to correlate structure and properties. The ternary antimonides are layered structures with two-dimensional square sheets or nets, which influence the properties of these materials. In an effort to determine how structural changes influence the physical properties, various single crystals of compounds relating to the orthorhombic CeNiSb3 structure have been grown and characterized. The layered CeNiSb3 structure consists of Sb sheets, NiSb6 distorted octahedra, and CeSb9 monocapped square anti-prisms. LnNi(Sn,Sb)3 …
Synthesis And Surface Characterization Of Silica-Polypeptide Composite Particles, Erick Isael Soto-Cantu
Synthesis And Surface Characterization Of Silica-Polypeptide Composite Particles, Erick Isael Soto-Cantu
LSU Doctoral Dissertations
The synthesis and sequential surface characterization of silica-polypeptide composite particles is described. Nearly monodisperse colloidal silica cores were obtained by the alkaline hydrolysis of tetraethyl orthosilicate (TEOS). The hydrodynamic radius can be easily controlled in the range of ƒî 20-140 nm by the water/TEOS ratio in the starting reaction mixture. The surface of the synthesized silica cores was further passivated/functionalized (P/F) by a mixture of (3-aminopropyl) trimethoxysilane (APS) and methyl-trimethoxysilane (MTMS). The amino groups were quantified using UV-Vis spectrometry after reaction with ninhydrin. The use of zeta potential measurements of the P/F silica particles at low pH is presented as …
Landscape Analysis Of Vegetation Change In Coastal Louisiana Following Hurricanes Katrina And Rita, Gregory Dean Steyer
Landscape Analysis Of Vegetation Change In Coastal Louisiana Following Hurricanes Katrina And Rita, Gregory Dean Steyer
LSU Doctoral Dissertations
Investigations of hurricane disturbances on coastal vegetated communities are common, but relatively few are comprehensive across broad geographic regions. The 2005 hurricanes, Katrina and Rita, exposed Louisiana coastal landscapes to physical modifications and extensive and prolonged flooding, resulting in measurable physicochemical changes. This research used remote sensing and field investigations to regionally assess (1) porewater salinity and sulfide impacts to and recovery of coastal Louisiana vegetation communities, and (2) the importance of mineral sediment deposition on accretionary processes. Hurricane effects were most direct and prominent in eastern Louisiana from Katrina and western Louisiana from Rita, compared to central Louisiana exposed …
Solid-Phase Synthesis Of Asymmetrically Substituted Phthalocyanines, Sultan Sibel Erdem
Solid-Phase Synthesis Of Asymmetrically Substituted Phthalocyanines, Sultan Sibel Erdem
LSU Doctoral Dissertations
Phthalocyanines (Pcs) are excellent candidates for use as fluorophores for near-infrared (near-IR) fluorescent tagging of biomolecules and as photodynamic therapy (PDT) agents. Synthesis of Pcs with asymmetrical substitution on the periphery is often difficult due to the problems during the purification of the Pc mixtures obtained. The objective of this project is to design and synthesize chemically robust near-IR fluorophores for bioanalytical applications and to develop new synthetic methods for rapid synthesis of the target compounds. A novel synthetic route was developed utilizing a hydrophilic, polyethylene glycol-based (PEG) support with different types of linkers. The Pcs were functionalized with either …
Surgery Description Of Colored Knots, Steven Daniel Wallace
Surgery Description Of Colored Knots, Steven Daniel Wallace
LSU Doctoral Dissertations
By a knot, or link, we mean a circle, or a collection of circles, embedded in the three-sphere S3. The study of knots is a very rich subject and plays a key role in the area of low-dimensional topology. In fact, a theorem of W.B.R. Lickorish and A.D. Wallace states that any three-dimensional manifold may be described by Dehn surgery along a link which is the process of removing the link from S3 and then gluing it back in a way that possibly changes the resulting manifold. In this dissertation, we will be interested in the pair (K, ρ) consisting …
Stochastic And Copula Models For Credit Derivatives, Chao Meng
Stochastic And Copula Models For Credit Derivatives, Chao Meng
LSU Doctoral Dissertations
We prove results relating to the exit time of a stochastic process from a region in N-dimensional space. We compute certain stochastic integrals involving the exit time. Taking a Gaussian copula model for the hitting time behavior, we prove several results on the sensitivity of quantities connected with the hitting times to parameters of the model, as well as the large-N behavior. We discuss the relationship of these results to certain credit derivative instruments. Relevant simulations are presented.
Exploration Of New Ternary Gallides And Investigation Of Their Structure-Property Relationships, Jung Young Cho
Exploration Of New Ternary Gallides And Investigation Of Their Structure-Property Relationships, Jung Young Cho
LSU Doctoral Dissertations
This dissertation focuses on the investigation of new ternary intermetallic gallides, which may exhibit exotic physical properties such as heavy-fermion behavior, large magnetoresistance, and even superconductivity. In particular, the Ln-Cu-Ga (Ln = lanthanides) system has been systematically investigated by changing a reaction ratio and/or using a different temperature profile to optimize desired phases. Single crystals of Ln2MGa12 (Ln = La, Ce; M = Ni, Cu) have been synthesized using Ga flux and compared to their Pd analogues. Interestingly, Ce2MGa12 (M = Ni, Cu) show enhanced Sommerfeld coefficient of ¡Ö 191 mJmol-1K-2 and ¡Ö 69 mJmol-1K-2 for Ni and Cu compounds, …
Revolutionizing Genomic Analyses: Mutation Analyses Using Novel Enzyme-Based Assays With Laser-Induced Fluorescence And Polymeric Microfluidic Devices As Electrophoretic Platforms, Rondedrick Deshaun Sinville
Revolutionizing Genomic Analyses: Mutation Analyses Using Novel Enzyme-Based Assays With Laser-Induced Fluorescence And Polymeric Microfluidic Devices As Electrophoretic Platforms, Rondedrick Deshaun Sinville
LSU Doctoral Dissertations
Polymer-based microelectrophoresis was investigated to analyze known (mutation detection) and unknown (mutation scanning) low-abundant mutations in genomic DNA with high diagnostic value for colorectal cancers. For our mutation detection assays, point mutations in the K-ras oncogene were identified using the ligase detection reaction (LDR). For the mutation scanning assay, which searches for sporadic mutations, an EndoV-LDR assay was utilized with mutations in the p53 tumor suppressor gene used as a model. A poly(methylmethacrylate), PMMA, microchip filled with a 4% linear polyacrylamide (LPA) gel was used to electrophoretically sort products formed from LDRs, which produced oligonucleotides <65 bp in length. Using microchip electrophoresis with the LPA, a 44 bp ligation product was resolved from a 100-fold molar excess of unligated primers (25 bp) in approximately 120 s, which was ~17 times faster than conventional capillary gel electrophoresis. In order to simplify the electrophoretic process and further reduce development time, the LDR products were sorted in the absence of the sieving gel using free solution conjugate electrophoresis (FSCE). FSCE incorporated polyamide “drag-tags” onto LDR primers, which provided DNA fragment mobilities in free solution that were dependent upon their size. LDR/drag-tagged (LDR-dt) products could be formed in a multiplexed format for mutant-to-wild-type ratios as low as 1 to 100 with single base resolution. Separations were conducted using capillary array electrophoresis (CAE) and PMMA microchips filled with only a TRIS buffer. Analysis times for the LDR-dt products were less than 11 min using CAE and ~85 s for PMMA microchips with high reproducible migration times within and between microchips. PMMA-based microchips were also evaluated for the identification of sporadic mutations using an endonuclease V – LDR (Endo V/LDR) technique. Endo V cleaves heteroduplexed DNA one base 3’ of single-base mismatched sites as well as nicking DNA at some matched sites as LDR reseals miscleaved sites to reduce false positive signals. Results suggested that Endo V/LDR products from p53 mutations could be successfully separated and detected using a PMMA microfluidic chip filled with a sparsely cross-linked replaceable polyacrylamide gel in less than 6 min, which was approximately 10-fold shorter compared to CAE.
Novel Devices And Protocols Enabling Isolation And Enumeration Of Low Abundant Biological Cells From Complex Matrices, Andre Antonio Adams
Novel Devices And Protocols Enabling Isolation And Enumeration Of Low Abundant Biological Cells From Complex Matrices, Andre Antonio Adams
LSU Doctoral Dissertations
The dimensions of microfluidic devices closely parallel those of biological cells; thusly, they are excellent platforms for the speciation, transport, manipulation, and analysis of cells. Electrokinetic transport of Escherichia coli and Saccharomyces cerevisiae was evaluated in microfluidic devices fabricated in pristine and UV-modified poly(methylmethacrylate) and polycarbonate. The magnitude and direction of transport of the cells was dictated by the buffer composition, conduit surface chemistry, and intrinsic cellular electrical properties. Baker’s yeast in all devices migrated toward the cathode, because of their smaller electrophoretic mobility compared to the electroosmotic flow of the polymer. E. coli cells suspended in 20 mM PBS …
Identification Of Quantitative Trait Loci Influencing Early Height Growth In Longleaf Pine (Pinus Palustris Mill), Lisha Wu
LSU Doctoral Dissertations
The delay in early height growth (EHG) has been a limiting factor for artificial regeneration of longleaf pine (Pinus palustris Mill.). Simple Sequence Repeat (SSR) markers have been used to map the genome and quantitative trait loci controlling the EHG in a backcross family (longleaf pine x slash pine) x longleaf pine. A total of 228 locus specific SSR markers were screened against 6 longleaf pine recurrent parents and a sample of 7 longlef x slash pine hybrid parents. In total, 135 polymorphic markers were identified. Based on the genetic variance in EHG, available sample size, and the number of …
Elucidating Marine Pore Water Exchange And Fresh Aquifer Sources In Estimates Of Submarine Groundwater Discharge To A Coastal Lagoon, Christopher Gerald Smith
Elucidating Marine Pore Water Exchange And Fresh Aquifer Sources In Estimates Of Submarine Groundwater Discharge To A Coastal Lagoon, Christopher Gerald Smith
LSU Doctoral Dissertations
Dynamic balances between fresh groundwater, saline groundwater, and surface water control the physics and chemistry of subterranean estuaries. Investigations were performed in a subterranean estuary on physical processes contributing to fresh groundwater and saline water mixing, vertical and lateral positioning of this mixing zone, and how this mixing affects spatial and temporal distributions of 234,238U, 226Ra, and 222Rn. The subterranean estuary is located in an unconfined aquifer beneath Indian River Lagoon, Florida, USA, where I could examine redox responses to altered flow regimes. Continuous groundwater and surface water level measurements suggest a strong hydrologic connection between this …
Space-Time Multiresolution Approach To Atomistic Visualization, Dipesh Bhattarai
Space-Time Multiresolution Approach To Atomistic Visualization, Dipesh Bhattarai
LSU Doctoral Dissertations
Time-varying three-dimensional positional atomistic data are rich in spatial and temporal information. The problem is to understand them. This work offers multiple approaches that enable such understanding. An interactive atomistic visualization system is developed integrating complex analyses with visualization to present the data on space-time multiresolution basis facilitating the information extraction and generate understanding. This work also shows the usefulness of such an integrated approach. The information obtained from the analyses represents the system at multiple length and time scales. Radial distribution function (RDF) provides a complete average spatial map of the distribution of the atoms in the system which …
Effect Of Hydrology On The Structure And Function Of Mangrove Ecosystems In The Can Gio Mangrove Biosphere Reserve, Vietnam, Loi Tan Le
LSU Doctoral Dissertations
The influence of hydrology on the mangrove forests of Vietnam has received little scientific attention, even though hydrology is recognized as the primary forcing function in mangrove ecosystems worldwide. The purpose of this dissertation research was to determine the effects of hydrology on specific structural attributes and functional processes within the mangrove forests of Can Gio, a province in southeastern Vietnam. Khe Vinh (KV) and Mui O (MO), two locations within compartment 17 of the Can Gio Mangrove Biosphere Reserve, were chosen as study sites. This research addressed two questions: (1) What are the characteristics of the hydrological regime at …
Differential Geometry In Cartesian Closed Categories Of Smooth Spaces, Martin Laubinger
Differential Geometry In Cartesian Closed Categories Of Smooth Spaces, Martin Laubinger
LSU Doctoral Dissertations
The main categories of study in this thesis are the categories of diffeological and Fr\"olicher spaces. They form concrete cartesian closed categories. In Chapter 1 we provide relevant background from category theory and differentiation theory in locally convex spaces. In Chapter 2 we define a class of categories whose objects are sets with a structure determined by functions into the set. Fr\"olicher's $M$-spaces, Chen's differentiable spaces and Souriau's diffeological spaces fall into this class of categories. We prove cartesian closedness of the two main categories, and show that they have all limits and colimits. We exhibit an adjunction between the …
Utilization Of Aptamers As Affinity Probes In Polymeric Microdevices For Disease Management And The Production Of A Recombinant Membrane Protein, Anne Obubuafo
LSU Doctoral Dissertations
Aptamers have emerged as potential affinity agents that rival or complement antibodies in developing diagnostic assays for disease detection. We have demonstrated the use of PMMA microfluidic devices for conducting rapid affinity microchip CGE of a target protein using aptamers as the affinity probes with an electrophoresis development time of <2 min. Migration times were reproducible for thrombin complexes and free aptamers in CGE buffer with device-to-device RSD variations below 10%. By removing salts from plasma and adding an unlabeled random sequence oligonucleotide to the plasma, thrombin was detected in plasma. This method can be easily adapted to high-throughput parallel screening of plasma samples in multi-channel polymeric microdevices. The expression of rEpCAM in bacteria and mammalian cells was investigated with results showing successful expression in the mammalian systems, while protein expression in the bacteria was inhibited. Higher and prolonged expression levels were obtained in Cos 7 cells as compared to BHK and Hep2 cells due to episomal expression in Cos 7 cells. By combining a one-step IMAC procedure with electrophoresis and electro elution a more selective approach to obtaining electrophoretically pure rEpCAM was achieved. We developed dual-aptamer sandwich assays for thrombin and PDGF-BB targets on PMMA substrate using UV modification with a one-step EDC/NHS coupling reaction. Results indicate that the use of high EDC concentrations lead to faster immobilization and increased coverage density with a shorter sandwich assay development time. The assays were sensitive for both proteins and showed linearity in fluorescence response to changing protein concentration. Single molecule detection methods provide high sensitivity techniques in which aptamers can find use. We have demonstrated the use of two aptamers in a FRET-based assay for the detection of low levels of thrombin. Sensitivity and reliability of the aptamer smFRET assay depends on complex formation and stability. Due to the dissociation constants of the aptamers, single molecule events detected were below the calculated value for a 6 pM concentration of thrombin. Future work will involve adjusting the single molecule system by the use of pinholes to enable analysis of higher sample concentrations.
Swamp Ecology In A Dynamic Coastal Landscape: An Investigation Through Field Study And Simulation Modeling, Susanne Sigrid Hoeppner
Swamp Ecology In A Dynamic Coastal Landscape: An Investigation Through Field Study And Simulation Modeling, Susanne Sigrid Hoeppner
LSU Doctoral Dissertations
Increased flooding, nutrient and sediment deprivation, and saltwater intrusion have been implicated as probable causes of coastal swamp deterioration in the Mississippi Delta. An understanding of the interactive effects of these factors is required to enable successful planning of wetland restoration activities. I used field data collected from 2000 till 2005 at forty study sites to characterize the baseline conditions of the Maurepas swamp. I used a cluster analysis to identify four swamp habitat clusters, and characterized the clusters on the basis of soil properties, salinity, basal area, stem density, and other tree-related variables. ANOVA and related statistical techniques showed …
Assessment Of Oxygen Sources And Sinks In The Northern Gulf Of Mexico Using Stable Oxygen Isotopes, Zoraida Jazmin Quinones-Rivera
Assessment Of Oxygen Sources And Sinks In The Northern Gulf Of Mexico Using Stable Oxygen Isotopes, Zoraida Jazmin Quinones-Rivera
LSU Doctoral Dissertations
Coastal hypoxia (< 2 mg O2L-1) represents a global problem that continues to worsen as nutrient fluxes to these areas increase. The second largest zone of human-induced hypoxia is located on the Louisiana continental shelf where hypoxic bottom waters commonly occur during summertime. This region is strongly impacted by the large flux of freshwater and nutrients from the Mississippi River, which influences both biological and physical processes that control oxygen dynamics. Yet, based on oxygen concentration measurements alone, it is difficult to separate the effects of biological factors from physical factors. To address this problem, I used a dual budget approach to assess the importance of oxygen sources and sinks on the Louisiana continental shelf. The dual budget was based on using stable oxygen isotopes (ä18O) in combination with conventional oxygen concentration measurements. To analyze temporal trends, surface and bottom water samples were collected monthly between July 2001 and July 2003 along an onshore-offshore transect. For better spatial resolution, shelfwide sampling was conducted extending from the Mississippi River Delta to the Louisiana-Texas border in the month of July of 2001, 2002, and 2003. Oxygen saturations values ranged between 180% at the surface and almost 0% close to the bottom with a corresponding range of ä18O values from 15‰ to 50‰. Biological parameters were important during all seasons for surface oxygen dynamics. The effects of physical factors were less apparent, except during severe physical disturbances. Bottom water oxygen dynamics showed clear seasonal signals of high oxygen depletion and larger contributions of benthic respiration during the summer, which corresponded to the strong stratification of the water column. In bottom waters, summer oxygen depletion was predominantly due to benthic respiration, accounting for about 73%, 80% and 60% of the total oxygen loss for 2001, 2002 and 2003 respectively. Model estimates of production/respiration (P/R) ratio during the July shelfwide cruises indicated that surface waters were productive with an average calculated P/R above 1. Depth stratified sampling (5 m intervals), which started in July 2002, showed that productivity in the mixed layer (5 to 10 m) was not homogeneous. Calculated P/R exceeded 1 only in the surface layer, while at 5 m P/R was approximately 1 and at a depth of 10 m, P/R was less than 1. Additionally, hypoxic conditions were only detected within 5 m of the bottom sediments. The dual budget approach yielded new estimates of productivity dynamics in surface waters and of sediment oxygen demand in bottom waters. For the first time, this study provided routine insight into productivity and respiration dynamics over large temporal and spatial scales. This could not have been accomplished using traditional methods because they commonly rely on time-consuming incubations. The study has shown that respiration dynamics in bottom waters vary seasonally with higher contribution of benthic respiration during stratified summer conditions and prevalent water column respiration during fall and winter. In contrast, seasonality in surface waters was less pronounced as productivity was more dependent on (salinity-inferred) nutrient supply than climatic forcing.
A Century Of Land Use And Water Quality In Watersheds Of The Continental U.S., Whitney P. Broussard Iii
A Century Of Land Use And Water Quality In Watersheds Of The Continental U.S., Whitney P. Broussard Iii
LSU Doctoral Dissertations
Human endeavors, particularly the agricultural and industrial activities of the last half century, now produce more biologically available nitrogen (N) than all other natural sources combined. The increased N availability can have consequences for the health of aquatic biota on the local, regional, and global scales. One manifestation of this problem is the formation of coastal hypoxic zones where terrestrial N loading creates eutrophic conditions in coastal waters. This dissertation examines a century of changes in land use and water quality to quantify the relationships between agricultural land use practices and riverine N yields in the Mississippi River Basin and …
Off-Line Maldi Mass Spectrometry Of Bioaerosols, Jae-Kuk Kim
Off-Line Maldi Mass Spectrometry Of Bioaerosols, Jae-Kuk Kim
LSU Doctoral Dissertations
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used for off-line analysis of bioaerosols. The overall goal of the work is to develop methods and instrumentation to minimize sample treatment and maximize sensitivity and selectivity for bioaerosol analysis. This work is divided into three parts: sample preparation, test bioaerosol analysis, and instrument development. Untreated silicon wafer substrates were used as an alternate to conventional stainless steel targets and proved to be excellent substrates for large molecule analyses as well as small molecule analyses with excellent spot-to-spot and shot-to-shot reproducibility, which is useful for high-throughput and automated sample analysis. MALDI sample preparation …
Investigation Of Superconductivity And Physical Properties Of Intermetallic Compounds: Mon, Mo₃Sb₇, Mgcni₃ And Transition Metal Diborides, Amar Bahadur Karki
Investigation Of Superconductivity And Physical Properties Of Intermetallic Compounds: Mon, Mo₃Sb₇, Mgcni₃ And Transition Metal Diborides, Amar Bahadur Karki
LSU Doctoral Dissertations
In this dissertation work, I report on the interesting results of our detailed investigations of the synthesis, structural, electrical and magnetic characterization of three different classes of intermetallic systems. Mo3Sb7 wires, thin films and microfibers exhibit the highest Tc ~ 8 K, which is substantially higher than the 2.2 K reported for the single crystal and powder of Mo3Sb7. The suppression of the spin fluctuations in Mo3Sb7 is evident by the absence of a parabolic dependence of magnetic susceptibility at 1 T. MoN wires, thin films and coated microfibers …
Visual Language Representation For Use Case Evolution And Traceability, Coretta Willis Douglas
Visual Language Representation For Use Case Evolution And Traceability, Coretta Willis Douglas
LSU Doctoral Dissertations
The primary goal of this research is to assist non-technical stakeholders involved in requirements engineering with a comprehensible method for managing changing requirements within a specific domain. An important part of managing evolving requirements over time is to maintain a temporal ordering of the changes and to support traceability of the modifications. This research defines a semi-formal syntactical and semantic definition of such a method using a visual language, RE/TRAC (Requirements Evolution with Traceability), and a supporting formal semantic notation RE/TRAC-SEM. RE/TRAC-SEM is an ontological specification employing a combination of models, including verbal definitions, set theory and a string language …
Dactyls Reveal Evolutionary Patterns In Decapod Crustaceans, Jeffrey Guy Agnew
Dactyls Reveal Evolutionary Patterns In Decapod Crustaceans, Jeffrey Guy Agnew
LSU Doctoral Dissertations
Because of their high preservation potential and uses in foraging and defense, decapod crustacean dactyls (movable fingers of claws) are potentially excellent test subjects for an ongoing debate concerning the relative importance of top-down (predators) and bottom-up (prey) controls on morphologic diversification and evolution. The utility of dactyls for inferring evolutionary patterns were evaluated using living and subfossil xanthoid crabs sampled from the southeast U.S. Atlantic and Gulf of Mexico coasts, and were used to: (1) distinguish the roles of selection and constraint on dactyl morphology through allometric and shape comparisons in the context of the crab’s phylogenetic relationships and …
Rice Straw Fiber Polymer Composites: Thermal And Mechanical Performance, Fei Yao
Rice Straw Fiber Polymer Composites: Thermal And Mechanical Performance, Fei Yao
LSU Doctoral Dissertations
Rice straw fiber can be considered as important potential reinforcing filler for thermoplastic composite because of its lignocellulosic characteristics. It is thus of practical significance to understand and predict the thermal decomposition process of rice straw fibers. A method proposed by Málek, Šesták, and co-workers was used to investigate and model thermal decomposition process of common natural fibers with detailed analysis on rice straw system. Assuming a global model occurring within the entire degradation of natural fibers with consideration of fiber as one pseudo-component, model can be used to describe both isothermal and non-isothermal degradation process of most selected fibers …
Fast Marching Methods - Parallel Implementation And Analysis, Maria Cristina Tugurlan
Fast Marching Methods - Parallel Implementation And Analysis, Maria Cristina Tugurlan
LSU Doctoral Dissertations
Fast Marching represents a very efficient technique for solving front propagation problems, which can be formulated as partial differential equations with Dirichlet boundary conditions, called Eikonal equation: $F(x)|\nabla T(x)|=1$, for $x \in \Omega$ and $T(x)=0$ for $x \in \Gamma$, where $\Omega$ is a domain in $\mathbb{R}^n$, $\Gamma$ is the initial position of a curve evolving with normal velocity F>0. Fast Marching Methods are a necessary step in Level Set Methods, which are widely used today in scientific computing. The classical Fast Marching Methods, based on finite differences, are typically sequential. Parallelizing Fast Marching Methods is a step forward for …
Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne
Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne
LSU Doctoral Dissertations
A diverse set of human diseases is associated with the misfolding of proteins into insoluble fibrillar structures that have predominantly β-sheet secondary structure. Thus it is imperative to elucidate the structural elements that contribute to β-sheet formation and stability. Peptides that autonomously form β-sheets are ideal models to study principles of protein folding and design. Gellman and coworkers first introduced an automonously folded β-hairpin (H-Arg-Tyr-Val-Glu-Val-Yyy-Xxx-Orn-Lys-Ile-Leu-Gln-NH2) that remained monomeric up to ~1 mM. Circular dichroism (CD) and nuclear magnetic resonance (NMR) analyses revealed that incorporation of non-stereogenic Aib-Xxx dipeptidyl sequences into i+1 and i+2 positions of a model peptide nucleates a …
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For The Analysis Of Collected Bioaerosols, Alton John Dugas
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For The Analysis Of Collected Bioaerosols, Alton John Dugas
LSU Doctoral Dissertations
The goal of this dissertation was to demonstrate collection, detection and identification of microorganisms from bioaerosols using offline matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the analysis of proteins. MALDI-MS intact bacteria techniques were adapted for use with an orthogonal MALDI quadrupole-time-of-flight mass spectrometer. Results indicate the instrument is capable of analyzing intact whole-cells. The first phase was to evaluate three bioaerosol samplers, an Andersen N6 single-stage impactor (AI), a cyclone impactor, and a vacuum filter system. The samplers collected test bioaerosols using a constructed bioaerosol exposure chamber (BEC). The BEC allowed all three samplers to operate in parallel. Each …
Limit On The Muon Neutrino Magnetic Moment And A Measurement Of The Ccpip To Ccqe Cross Section Ratio, Serge Arisitde Ouedraogo
Limit On The Muon Neutrino Magnetic Moment And A Measurement Of The Ccpip To Ccqe Cross Section Ratio, Serge Arisitde Ouedraogo
LSU Doctoral Dissertations
A search for the muon neutrino magnetic moment was conducted using the Mini- BooNE low energy neutrino data. The analysis was performed by analyzing the elastic scattering interactions of muon neutrinos on electrons. The analysis looked for an excess of elastic scattering events above the Standard Model prediction from which a limit on the neutrino magnetic could be set. In this thesis, we report an excess of 15.3}6.6(stat)}4.1(syst) elastic scattering events above the expected background. At 90% C.L., we derived a limit on the muon neutrino magnetic moment of 12.7~ 10−10ƒÊB. The other analysis reported in this thesis is a …
Gas-Phase Formation Of Environmentally Persistent Free Radicals From Thermal Degradation Of Catechol, Hydroquinone, Phenols And Tobacco, Julien Gnonlonfoun Adounkpe
Gas-Phase Formation Of Environmentally Persistent Free Radicals From Thermal Degradation Of Catechol, Hydroquinone, Phenols And Tobacco, Julien Gnonlonfoun Adounkpe
LSU Doctoral Dissertations
Catechol, hydroquinone and Phenol are major constituents of the mainstream tobacco smoke. The toxicity of tobacco has been attributed to the ability of catechol and hydroquinone to undergo endogenous or exogenous redox cycling to form semiquinone type radicals responsible of Reactive Oxygen Species (ROS) formation. ROS such as hydroxyl radicals can cause severe oxidative stress on biological tissues and can provoke severe signaling pathways leading to cardiovascular and pulmonary dysfunctions and carcinogenesis. Given that semiquinone type radicals are organic radicals, characterized by their high instability and reactivity; it is somewhat surprising that they can live long enough mostly when associated …
Chemical Analysis Of Polymer Blends Via Synchrotron X-Ray Tomography, Heath Alan Barnett
Chemical Analysis Of Polymer Blends Via Synchrotron X-Ray Tomography, Heath Alan Barnett
LSU Doctoral Dissertations
Material properties of industrial polymer blends are of great importance. X-ray tomography has been used to obtain spatial chemical information about various polymer blends. The spatial images are acquired with synchrotron X-ray tomography because of its rapidity, good spatial resolution, large field-of-view, and elemental sensitivity. The spatial absorption data acquired from X-ray tomography experiments is converted to spatial chemical information via a linear least squares fit of multi-spectral X-ray absorption data. A fiberglass-reinforced polymer blend with a new-generation flame retardant is studied with multi-energy synchrotron X-ray tomography to assess the blend homogeneity. Relative to other composite materials, this sample is …
Growth And Properties Of Metal-On-Metal Nanostructures: Ag On Cu(110) And Co On Ag(110), Indrajith Chandima Senevirathne
Growth And Properties Of Metal-On-Metal Nanostructures: Ag On Cu(110) And Co On Ag(110), Indrajith Chandima Senevirathne
LSU Doctoral Dissertations
Heteroepitaxial nanostructures have a diverse array of applications and show novel phenomena that arise from the exotic physics exhibited in reduced dimensions. We have investigated two nano-structured systems in order to gain insights into the dynamics of their nucleation, growth and have observed striking differences, due in part to a competition between lattice strain, surface and interfacial free energies. When Ag is deposited on clean, single-crystal Cu(110), it initially wets the surface with a (111) monolayer, and spontaneously nucleates nanowires as the coverage is increased. The nanowires nucleate at defects and step edges and grow aligned along the [1–10] direction. …