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Full-Text Articles in Physical Sciences and Mathematics

Application Of Biomass Derived Materials In Nanocomposites And Drilling Fluids, Kunlin Song Jan 2016

Application Of Biomass Derived Materials In Nanocomposites And Drilling Fluids, Kunlin Song

LSU Doctoral Dissertations

Tar is inevitably produced from biomass thermochemical processes, and is often disposed as an industrial waste, leading to environmental pollution. As a result of its high carbon content, tar was expected to be a promising precursor for manufacturing carbon materials. Consequently, low-cost porous carbon nanofibers (CNFs) using tar, polyacrylonitrile (PAN), and silver nanoparticles was fabricated through electrospinning and subsequent stabilization and carbonization processes. The continuous electrospun nanofibers were obtained with diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased fiber diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. …


Temporal Dynamics Of Benthic Responses To Habitat Disturbance In Coastal Plain Headwaters Of Southwestern Louisiana, Catherine Elizabeth Murphy Jan 2016

Temporal Dynamics Of Benthic Responses To Habitat Disturbance In Coastal Plain Headwaters Of Southwestern Louisiana, Catherine Elizabeth Murphy

LSU Doctoral Dissertations

Weak biotic responses to habitat gradients within Northern Gulf of Mexico streams have been attributed to spatial and temporal variability. Landscape and in-stream habitat descriptions are presented for watersheds within Pleistocene terraces of the Coastal Plains geomorphic province of Louisiana, USA. Geologic influences on stream habitat were inferred by comparing multivariate ordinations on physicochemical measurements between terraces. Seasonal variability was assessed during a drought year (2011) and a typical water year (2013). Within coastal plains of Louisiana, stream condition was more similar within terraces than within river basins. Permutational MANOVA models indicated significantly different stream habitat between Uplands and Prairie, …


Quantitative Oil Source-Fingerprinting Techniques And Their Application To Differentiating Crude Oil In Coastal Marsh Sediments, Buffy Marie Meyer Jan 2016

Quantitative Oil Source-Fingerprinting Techniques And Their Application To Differentiating Crude Oil In Coastal Marsh Sediments, Buffy Marie Meyer

LSU Doctoral Dissertations

Oil source-fingerprinting is an environmental forensics technique that uses analytical chemistry to determine the origin of oil residues in environmental samples by comparison to a known or suspected source oil. Currently, the only standardized method for oil source fingerprinting is a qualitative approach that is very effective in almost every oil spill response situation. However, the need for quantitative oil source-fingerprinting methods to complement the qualitative determinations is extremely desired. The research herein aims to utilize data generated by gas chromatography/mass spectrometry (GC/MS) methodologies to test two different quantitative techniques: diagnostic biomarker ratio analysis and chemometrics. The most common crude …


Ecological-Hydrological Feedback In Forested Wetlands, Scott Thomas Allen Jan 2016

Ecological-Hydrological Feedback In Forested Wetlands, Scott Thomas Allen

LSU Doctoral Dissertations

In forested wetlands, the biotic and abiotic consequences of water level variability is not well understood. The effects of flooding on carbon and water exchanges are important knowledge gaps where progress could benefit management of natural resources and predicting of changes in surface geophysical cycles. Two specific needs are a better understanding of (1) wetland tree responses to hydrologic variations, and (2) the effects of the forest and associated tree stressors on surface energy and water fluxes. Objectives were to determine effects of flooding on evaporation rates and energy dynamics, tree water use and growth responses to river-floodplain connectivity and …


Arsenic Speciation And Phytoremediation Modeling For Environmental Management, Sidney Joseph Marlborough Jan 2016

Arsenic Speciation And Phytoremediation Modeling For Environmental Management, Sidney Joseph Marlborough

LSU Doctoral Dissertations

Arsenic has been used throughout recorded history but during the industrial revolution widespread use led to global environmental impact. The two forms that should be considered in environment management are arsenate and arsenite. The calculations of environmental risk for arsenic exposure relies the toxicity of arsenite however, in well aeriated surface soils arsenate may be the predominate form. Ecological risk assessments based on arsenite studies will lead to restrictive remediation requirements that do not adequately reflect the level of risk. Arsenate resembles phosphate and as such has a greater affinity for phytoremediation. Phytoremediation is one of the most viable and …


Vegetation Influences Microbial Community Structure And Methane Emissions In Southeastern Louisiana Wetlands, Anthony Jason Rietl Jan 2016

Vegetation Influences Microbial Community Structure And Methane Emissions In Southeastern Louisiana Wetlands, Anthony Jason Rietl

LSU Doctoral Dissertations

Methane has a warming potential 28 times that of carbon dioxide and has been increasing in the Earth’s atmosphere since 1750. An understanding of the dynamics of methane emissions from natural sources is becoming increasingly important as we may need to mitigate emissions from these sources in the future to help reduce the effects of climate change. Wetlands are the single largest natural source of methane; however, little attention has been given to how plant species, biota, and interactions between above and belowground communities and microbial communities may affect methane emissions. First, microbial community structure and function was assessed for …


Immune Gene Variation And Susceptibility To Upper Respiratory Tract Disease In Gopher Tortoises, Jean Pierre Elbers Jan 2016

Immune Gene Variation And Susceptibility To Upper Respiratory Tract Disease In Gopher Tortoises, Jean Pierre Elbers

LSU Doctoral Dissertations

The immune system defends the host from bacteria, fungi, parasites, and viruses. The immune system is partially under genetic control through immune response genes, such as those of the major histocompatibility complex (MHC) whose nucleotide variation influences the host’s ability to recognize foreign pathogens and can influence disease susceptibility. Populations of threatened species generally possess low levels of genetic variation, and genetically depauperate hosts may be at greater risk of infectious disease contributing to extirpations because they also possess low immunogenetic variation. My dissertation examines the relationship between immunogenetic variation and disease susceptibility and the factors that influence innate immune …


Biomass Gasification For Electricity Generation: An Integrated Approach For Development Of Forest Residue-Based Projects In Rural India, Anand Mishra Jan 2016

Biomass Gasification For Electricity Generation: An Integrated Approach For Development Of Forest Residue-Based Projects In Rural India, Anand Mishra

LSU Doctoral Dissertations

Biomass gasification is generally regarded as a promising technology for various advanced application in energy production. Biomass is the only carbon-based sustainable option among the renewable energy sources. This study is focused on fostering biomass gasification for electricity generation sector in India. The study addresses four broad aspects of biomass gasification for electricity generation - feedstock properties and gasification technology, policy and regulatory framework governing the sector, financial evaluation of electricity generation from biomass gasification, and feedstock supply. The study is divided in four chapters, each of which addresses one aspect of electricity generation through biomass gasification. Based on literature, …