Physical Sciences and Mathematics Commons^™

A Systematic Multiscale Investigation Of Nanoparticle-Assisted Co2 Enhanced Oil Recovery (Eor) Process For Shale Oil Reservoirs, Dayo A. Afekare

LSU Doctoral Dissertations

Shale oil reservoirs are prolific on the short term due to hydraulic fracturing and horizontal drilling but experience significant production decline, leading to poor ultimate recovery and leaving billions of barrels of oil buried in the ground. In this study, a systematic multi-scale investigation of an enhanced oil recovery (EOR) process using relatively inexpensive silicon dioxide nanoparticles and carbon dioxide for shale oil reservoirs was conducted. Using the Tuscaloosa Marine Shale (TMS) as a case study, aqueous dispersions of nanosilica in conjunction with CO₂ were investigated at nano-to-core scales. At the nanoscale, atomic force microscope was used to investigate …

Investigations Of The Structure And Protein-Protein Interactions Of Chlamydia Trachomatis Scc4, Thilini Oshadhi Senarath Ukwaththage

LSU Doctoral Dissertations

Chlamydia trachomatis (CT) is the most common, sexually transmitted bacterial disease (STD) in the world. In the developmental cycle of CT, specific chlamydia chaperone 4 (Scc4) is a unique protein with essential and multiple roles. Hence, Scc4 is significant as a virulence target for therapeutic approaches to treat chlamydial infections. A novel approach was discovered to purify tag free Scc4 by utilizing a 6X-histidine-tag on Scc1 in the co-expressed Scc4:Scc1 complex by capturing the complex on nickel-charged immobilized metal affinity chromatography resin, followed by dissociation of Scc4 with sarkosyl. Using triple resonance NMR experiments, backbone and sidechain resonances …

Development Of Engineered Soil Surrogates For Modeling Natural Soil Sorption Behavior, Ghada Yehia Abdalla

LSU Doctoral Dissertations

The land produces more than 95% of the global food supply, and with a continuously growing population, we need to optimize the use of the available agricultural land. Soil organic matter (SOM) is an essential component of soils, especially concerning their fertility and sorption behavior. The chemical composition of the SOM consists of lipids, lignin, and cellulose. However, the heterogeneous and complex nature of SOM, and real soils, makes their study challenging and introduces uncontrollable factors.

Therefore, structural mimics of natural soils with increasing complexity representing the real soil functionality were synthesized and evaluated for bulk properties related to their …

Deep-Ultraviolet Laser Ablation For Biomolecular Analysis, Oluwaremilekun Omowunmi Lawal

LSU Doctoral Dissertations

New sampling and ionization techniques were developed using a deep-ultraviolet (DUV) laser at 193 nm wavelength for analysis of large biomolecules. A micrometer spatial resolution DUV laser ablation and capture system was constructed to sample tissue biomolecules. The spot size measurements of the focused beam showed that subcellular spots with ca. 2 μm diameter can be readily achieved with this wavelength. To demonstrate the extraction of tissue biomolecules with the DUV laser, regions of tissue sections were ablated and captured for offline proteomic and genomic analysis. The proteomic studies revealed that the tissue proteins were ejected without fragmentation and that …

Structure And Dynamics Of Phospholipid Vesicles And The Dependence On Nanoscale Interactions With Molecules Of Varying Complexity, Lakshapathy Widanelage Judith Upeka De Mel

LSU Doctoral Dissertations

In this dissertation, molecular interactions and changes imposed by nano-scale structures on phospholipid vesicles were investigated. 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) large unilamellar vesicles (LUVs) were used as the model system. Understanding changes of the bilayer structure, interfacial properties, lipid dynamics, and self-assembly, allows bridging relationships between biological cell membrane structure and dynamics to cellular functionalities. For example, membrane curvature changes are linked to membrane protein functions, although the exact mechanisms of control are not yet understood. Moreover, the knowledge gained from vesicle models allows exploring novel strategies for drug delivery applications. To achieve this, DOPC LUVs were synthesized and characterized by a …

Antimicrobial Strategies For Topical Applications, Kelsey Marie Lopez

LSU Doctoral Dissertations

Bacteria can thrive in diverse environments and are often harmless or beneficial. Bacteria in digestive tracts is one example of beneficial bacteria; however, bacteria can be harmful and when this type proliferates, it can cause infections within hosts. Bacterial infections are easily treated with antibiotics in most cases. However, bacteria are also capable of developing mutations which could cause them to become multi-drug resistant and eventually, “superbugs.” Therefore, the development of novel antimicrobial agents and materials capable of combating drug-resistant bacteria is necessary. Research presented in this dissertation focuses on different strategies for minimizing and preventing topical bacterial infections using …

Synthesis, Characterization, And Investigation Of Metal Ion Quenching In Fluorescent Carbon Dot Surrogates For Particulate Matter Black Carbon And Evaluation Of Cellular Health Effects Due To The Surrogate Materials, Christopher Lee Sumner Jr

LSU Doctoral Dissertations

Black carbon (BC) is an environmental pollutant of particular concern to many international organizations for both its health effects and environmental effects. Probing health effects of BC as produced in the environment is difficult due to the complex nature of environmental pollutants found in their naturally occurring state. Fluorescent carbon dots (FCDs) were chosen to be used as a surrogate for BC. In the process of examining FCDs and their behavior as surrogates, information was gained on the health effects and behavior of FCDs as a class of nanomaterials for cell and tissue studies, which is outlined in this dissertation. …

Assessment Of Soil Protein And Refractory Soil Organic Matter Across Two Chronosequences Of Newly Developing Marshes In Coastal Louisiana, Usa, Stuart Alexander Mcclellan

LSU Doctoral Dissertations

The impacts of sea-level rise and hydrologic manipulation are threatening the stability of coastal marshes throughout the world, thereby increasing the potential for re-mineralization of soil organic matter (SOM) in these systems. Such threats have prompted marsh restoration efforts, particularly in coastal Louisiana, yet it is unclear how the slowly decomposing (refractory) and quickly decomposing (labile) fractions of SOM may be differentially affected by different approaches to marsh restoration. Additionally, otherwise labile compounds may accumulate in the soil via a range of protective mechanisms, including rapid burial and association with organic compounds that are thought to enhance soil aggregation, such …

The Effects Of Temperature On The Yields Of Aliphatic And Aromatic Products From The Supercritical Pyrolysis Of 1-Octene, Elizabeth Anne Hurst

LSU Doctoral Dissertations

Prior to their combustion, fuels for future high-speed aircraft are expected to experience supercritical conditions, leading to the production of polycyclic aromatic hydrocarbons (PAH), precursors to solid carbonaceous deposits, via pyrolytic reactions. These solid deposits can clog fuel-transfer lines, causing unsafe aircraft operation. To prevent the formation of fuel-line deposits, it is critical to understand the reaction pathways that lead to PAH formation in the supercritical fuel pyrolysis environment.

To better understand the role of large 1-alkenes in PAH formation, supercritical pyrolysis experiments with model fuel 1-octene, a representative 1-alkene product from supercritical n-alkane pyrolysis, have been performed. The …

Electrification Ionization: Fundamentals And Applications, Bijay Kumar Banstola

LSU Doctoral Dissertations

Electrification ionization is a method to produce ions from solid samples by charge separation. This separation of charge can be enhanced by organic molecules known as matrix compounds to produce highly charged molecules. In this research, new methods were developed for the application of electrification ionization for surface analysis and the ionization mechanism was investigated. First, an electrification ionization matrix was used for tissue imaging using laser ablation. A two-component matrix of 2-nitrophloroglucinol and silica nanoparticles was found to increase the number of multiply charged ions from the tissue. Images of mouse brain with multiply charged ions were obtained. In …

Quartz Crystal Microbalance Based Sensors For Detection And Discrimination Of Volatile Organic Compounds Using Ionic Materials, Stephanie R. Vaughan

LSU Doctoral Dissertations

Volatile organic compounds (VOCs) are prevalent in everyday life, ranging from household chemicals, naturally occurring scents from common plants and animals, to industrial-scale chemicals. Many of these VOCs are known to cause adverse health and environmental effects and require regulation to prevent pollution. Detecting VOCs plays a critical role in food quality control, environmental quality control, medical diagnostics, and explosives detection. Thus, development of adequate sensing devices for detection and discrimination of VOCs is of great importance. In recent years, use of quartz crystal microbalance (QCM) based sensor arrays for analyses of VOCs has attracted significant interest. Detection of VOCs …

In Vitro Evaluation Of Ovarian Cancer Tumorigenesis As A Function Of Quinone Oxidoreducatse-1 And Cell Phenotype, Milcah S. Jackson

LSU Doctoral Dissertations

In vitro multicellular spheroids are attractive model systems for assessing genetic and epigenetic changes that occur in diseased tissues. Understanding how such alterations in gene and subsequent protein expression affect disease progression and metastasis, drug resistance, and recurrence is of great interest in cancer research. In this regard, examining expression and activity of proteins, such as those with cytoprotective ability that are overexpressed in cancer cells, in addition to cell phenotype (i.e., stem-like, epithelial, mesenchymal, or mixed), are two ways to evaluate genetic and epigenetic changes. Moreover, determining the impact that cytoprotective proteins and cell phenotype have on tumor formation …

Chemical Approaches For Nanofabrication Based On Colloidal Lithography With Organosilanes, Nanoparticles And Nickel Films: The Role Of Water In Directing Surface Self-Assembly, Neepa Malsi Kumari Kuruppu Arachchige

LSU Doctoral Dissertations

The capabilities for accomplishing fundamental surface studies with molecular systems are demonstrated in this dissertation using measurement and imaging modes of scanning probe microscopy. Model systems were chosen for investigations of surface self-assembly mechanisms, with an emphasis on understanding the role of interfacial water in surface reactivity. A key strategy for molecular level studies was to prepare nanostructures using protocols with colloidal lithography and scanning probe-based lithography (SPL). Nanofabricated samples were characterized ex situ with contact and tapping-mode atomic force microscopy (AFM) after key reaction steps, providing direct views of changes in surface morphology at the nanoscale. Magnetic sample modulation …

Photo-Physical Properties Of Novel Gumbos For Optoelectronic Applications, Thenahandi Prasanthi Deepthika De Silva

LSU Doctoral Dissertations

Organic Light Emitting Diodes (OLEDs) are predicted to revolutionize next generation consumer electronics by offering many advantageous device characteristics, including low power consumption, low heat dissipation, a tunable and wider color gamut, high resolution and contrast, light weight, flexibility, and semi-transparency. However, a major limiting factor for OLEDs to reach their full potential is that only a few known blue OLED emitters with substantial spectral purity and longevity are available to date. Therefore, focus of this research is on understanding and addressing limitations of OLED emitters, with an emphasis on improving the characteristics of blue emitters.

The work presented in …

Infrared Laser Ablation For Biomolecule Sampling, Kelin Wang

LSU Doctoral Dissertations

In this research, an infrared laser at a wavelength of 3 µm was used to ablate material from tissue sections for biomolecule analysis. Pulsed infrared (IR) irradiation of tissue with a focused laser beam efficiently removed biomolecules, such as proteins, enzymes, DNA, and RNA from tissue sections for further analysis. In a proteomics project, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) was used to determine regions of interest (ROI) for laser ablation. The matrix was then washed off. By overlaying the MSI generated heat-map, the section was sampled using IR laser ablation and custom stage-control software. Two ROI were selected …

Improving Coupled Enzyme Assays With Capillary Electrophoresis, Thu Hoai Nguyen

LSU Doctoral Dissertations

The goal of this project is to address limitations of coupled enzyme assays using capillary electrophoresis (CE). In some enzyme assays, it is ineffective to directly detect products and substrates spectroscopically (absorption or fluorescence). Coupling the enzyme-catalyzed reaction of interest with another enzyme-catalyzed reaction allows for indirect detection of product formation or substrate depletion for the target enzyme. While conventional coupled enzyme assays are facile for kinetic measurements, they can be problematic for inhibition screening due to spectral and inhibitor interferences. To address these limitations of coupled assays, CE has been used to develop enzyme assays for acetyl-coenzyme A carboxylase …

Atomic Force Microscopy Tip-Enhanced Laser Ablation, Fan Cao

LSU Doctoral Dissertations

In the present work, an apertureless atomic force microscope (AFM) tip-enhanced laser ablation (TELA) system was developed and investigated. An AFM was coupled to an optical parametric oscillator (OPO) wavelength tunable laser for sample ablation with a submicron sampling size. The AFM was used to image the surface and hold the AFM tip 10 nm above the sample surface. The AFM tip is coated with a layer of gold with a thickness of 35 nm. The incident laser wavelength was tuned in the visible and near-infrared (IR) region and focused on the AFM tip. With the tip-enhancement effect, ablation craters …

Influence Of Salinity, Sunlight, And Sediment On The Toxicity Of Pesticides In Three Non-Target Organisms, Emily Noelle Vebrosky

LSU Doctoral Dissertations

Pesticides used in the United States must undergo registration by the United States Environmental Protection Agency (USEPA), after a multitude of analyses ranging from environmental fate to aquatic toxicological impacts to human risk exposure. Testing varies for each chemical, some requiring more testing than others. In many cases, environmental factors are restricted in the analysis of chemical behavior and organismal testing is limited to larvae. Many pesticides are formulated to breakdown in the environment by means of photolysis, hydrolysis, or oxidation, either to ensure low-persistence, limited transport, or to form the active ingredient (pro-pesticides). Environmental influences on chemical behaviors include …

Nmr Structural Investigation Of Chlamydial Protein Complex And Lysine Glycomimetic For Drug Design, Abigael Chebichiy Songok

LSU Doctoral Dissertations

Research and design of drugs for treatment against microbial infections require the study of pathogenic proteins involved during infection and replication. Drugs can be designed to interfere with the interaction network of these pathogenic proteins and inhibit the infection process. Determination of the structure and ligands of the target proteins in microbes is essential for designing mechanistic-based drugs. Two Chlamydia proteins involved in host cell invasion were investigated in this study. The goal is to identify amino acids involved at the binding interface of Chlamydia chaperon proteins Scc1 and Scc4 by solution NMR spectroscopy. This information will give a lead …

Visualization And Quantification Of Cancer-Associated Enzymes With Fluorescent Small-Molecule Substrate Probes, Zhenhua Shen

LSU Doctoral Dissertations

Fluorescence imaging can be used both as a tool to diagnose diseases and guide treatment in clinical settings, and as a technique to monitor dynamic events or biological species in basic research. Therefore, there is a great need for the development of a multitude of fluorescent probes that can be incorporated with fluorescence imaging techniques to track and report endogenous enzymes with high specificity and selectivity. In contrast to always-on and targeted always-on fluorescent probes that continually emit light, activity-based substrate probes either emit low numbers of photons or are completely quenched. They can be converted to highly fluorescent reporters …

Chemotherapeutic Applications Of Rhodamine Based Nanogumbos, Nimisha Bhattarai

LSU Doctoral Dissertations

The work presented in this dissertation employs nanomaterials derived from a group of uniform materials based on organic salts (GUMBOS) for selective chemotherapeutic applications. GUMBOS, similar to ionic liquids, are organic salts consisting of a bulky cationic and anionic moiety. In contrast to ionic liquids, these materials have melting points ranging from 25–250 °C, making them solid phase at room temperature. Similar to ionic liquids, GUMBOS display tunable properties, such as hydrophobicity and solubility, through counter ion variation. These tunable properties provide a variety of applications for these GUMBOS, including selective chemotherapeutics applications. The …

Biomedical Applications Of Hydrogels And Gumbos, Kelsey Elizabeth Mcneel

LSU Doctoral Dissertations

Sodium deoxycholate (NaDC) is a small bile salt that was used in this dissertation to produce gelation of tris(hydroxymethyl)amino-methane (TRIS) solutions above, below, and near the pKa of NaDC. These solutions respectively yielded a neutral gelator, a charged gelator, and a mixture of each. Impacts of ionic interactions on gel formation were studied in detail and showed that pH can be used to modify many hydrogel properties including sol-gel temperature, crystallinity, and mechanical strength. It was also observed that pH modification of the hydrogels affected nanoparticle formation. Nanoparticles derived from a Group of Uniform Materials Based on Organic Salts (nanoGUMBOS), …

Nanopatterns Of Zinc Phthalocyanines, Gold Nanoparticles, And Porphyrins Prepared Using Particle Lithography: Characterization Of Patterning Steps With Scanning Probe Microscopy, Ashley Marie Taylor

LSU Doctoral Dissertations

The growth and self-assembly of molecules on surfaces can be directly visualized at the molecular level using studies which combine nanoscale lithography and high-resolution imaging. Nanopatterning provides a unique and practical approach for direct views of surface changes after the key chemical steps of nanopatterning, providing landmarks and baselines for measuring growth in vertical and lateral dimensions. Controlling the arrangement of materials on surfaces at the nanoscale can be achieved using particle lithography. Arrays of well-defined nanostructures can be prepared with reproducible geometries and arrangement. Results for the preparation of nanopatterns produced with particle lithography are presented using high resolution …

Self-Assembly Mechanisms Of Organosilanes And Porphyrins Investigated With Scanning Probe Microscopy, Phillip Charles Chambers Ii

LSU Doctoral Dissertations

This dissertation details the development of new fabrication strategies for the preparation of spatially selective surfaces by combining techniques of particle lithography and scanning probe microscopy (SPM). This combination of lithography and nanoscale surface characterization was applied to study the mechanisms of molecular level surface-assembly of organosilanes and porphyrin on surfaces of Si(111). Particle lithography was used to investigate the surface assembly of 4-chloromethylphenyltrichlorosilane (CMPS) within exposed sites of nanoholes in selected solvents and at selected temperatures to gain insight into the details of self-polymerization. Nanopillars of CMPS were generated under selected conditions of solvent and temperature and characterized with …