Forest Sciences Commons^™

Characterization Of Lignin Structural Variability And The Associated Application In Genome Wide Association Studies, Nathan D. Bryant

Doctoral Dissertations

Poplar (Populus sp.) is a promising biofuel feedstock due to advantageous features such as fast growth, the ability to grow on marginal land, and relatively low lignin content. However, there is tremendous variability associated with the composition of biomass. Understanding this variability, especially in lignin, is crucial to developing and implementing financially viable, integrated biorefineries. Although lignin is typically described as being comprised of three primary monolignols (syringyl, guaiacyl, p-hydroxyphenyl), it is a highly irregular biopolymer that can incorporate non-canonical monolignols. It is also connected by a variety of interunit linkages, adding to its complexity. Secondary cell wall …

Quantifying Spatial Heterogeneity Of Wild Blueberries And Crop Water Stress Monitoring Using Remote Sensing Technologies, Kallol Barai

Electronic Theses and Dissertations

The wild blueberry is one of the major crops of Maine, with significant economic value and potential health benefits. Due to global climate change, drought impacts have been increasing significantly in recent years in the northeast region of the USA, causing significant economic losses in the agricultural sectors. It has been predicted to increase further in the future. Changing patterns of the elevated atmospheric temperatures, increased rainfall variabilities, and more frequent drought events have made the wild blueberry industry of Maine vulnerable, suggesting the adoption of novel approaches to mitigate the negative impacts of global climate changes. Also, wild blueberry …

Recovering And Upgrading Kraft Lignin For Application In Flexible Polyurethane Foam, Peng Quan

Dissertations, Master's Theses and Master's Reports

Lignin is the second abundant natural polymer and has been highlighted as a potential substitute for fossil-based raw materials. However, the inherent molecular heterogeneity and the complex recovery processes result in the challenge of controlling the molecular properties and value-added applications of lignin in large scale. To address those issues, a novel acid-liquefaction process was developed in this study to recover Kraft lignin with improved molecular homogeneity directly from black liquor.

In the first study, the liquefaction parameters were screened based on yield and molecular weight properties of the recovered lignin. Then, the recovered lignin samples were used to replace …

Understanding The Adhesion Mechanism In Mycelium-Assisted Wood Bonding, Wenjing Sun

Electronic Theses and Dissertations

The increasing environmental awareness has led to an increased interest in developing more sustainable materials as alternatives to petroleum-derived products. Among different nature-based products, fungal-mycelium-based bio-composites have gained considerable attention in various applications. Multiple materials with different densities and structures and potential applications can be fabricated by inoculating filamentous white-rot fungi in lignocellulosic materials and other substrates. Different from lower-density as-grown foam-like mycelium composites, higher-density mycelium-lignocellulosic panels have the potential to replace commercial particleboard and fiberboard bonded by petroleum-based resins. This kind of composite can be produced by directly adding heat and pressure to the low-density foams or by assembling …

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …

Valorization Of Xylan In Agroforestry Waste Streams, Harrison Appiah

Graduate Theses, Dissertations, and Problem Reports

Valorization of Xylan in Agroforestry Waste Streams.

Harrison Appiah

Microwave-assisted deep eutectic solvent and gamma-valerolactone metallic chloride catalyzed conversion of xylan to furfural were investigated using a 2x3 factorial experimental design at two levels of percent microwave power, reaction time, and catalyst concentration. The levels of each factor studied were (20%, 60% microwave power, 2, 4 minutes, and 10, 20mg) respectively. The effect of three metallic chloride catalysts (LiCl, FeCl3.6H20, CuCl2) on the conversion of xylan to furfural was also investigated. The gamma-valerolactone-ferric chloride sent system exhibited the highest mean yield of furfural (56.50%). The next highest furfural yield of …

Lignocellulosic Biomass Derived Activated Carbon For Energy Storage And Adsorption, Changle Jiang

Graduate Theses, Dissertations, and Problem Reports

Lignocellulosic biomass has been converted to hierarchical porous carbon materials which possess macro-, meso- and micro-pores. The natural structure of porous lignocellulosic structure was preserved during activation with further developed porosity by the activation. The activated carbon can be well applied to electrochemical double layer capacitor for transportation storage of ions as well as adsorbent materials for metal ion removal from wastewater.

The first chapter of this dissertation presents an introduction of biomass derived carbon and its applications. In the second chapter, both direct and indirect activation methods using carbon dioxide were adopted in this study. The results show that …

Characteristics Of Activated Carbons Produced From Herbaceous Biomass Feedstock, Oluwatosin Jerry Oginni

Graduate Theses, Dissertations, and Problem Reports

Energy security and environmental protection are at the forefront of research due to the forecasted depletion of fossil fuel reserves and the growing concern of its adverse environmental impacts. The use of renewable sources for energy applications has centered on the use of biomass feedstocks and this include from herbaceous, woody, agricultural waste, forest residues and municipal wastes. The thermochemical conversion (pyrolysis) of these biomass feedstocks has potential to produce liquid fuel, a solid residue (biochar) and non-condensable gas. The biochar is primarily composed of renewable porous carbon and other inorganic compounds. The biochar is used for soil amendment, adsorption …

A Risk-Based Method For Estimating The Carbon Sequestration Budget For A Mixed Hardwood Forest, Erin Cooper

Chemical Engineering Undergraduate Honors Theses

Carbon Dioxide (CO₂) levels in the atmosphere have risen from approximately 310 ppm in the 1950’s to over 400 ppm as of 2015. This rise in CO₂ has likely resulted in the observed warming trend of the earth’s atmosphere in the same time frame, causing significant concern in the scientific community. Several mitigation strategies have arisen to combat the upward trend of CO₂ emissions in recent decades, among them being carbon sequestration- the process of capturing CO₂ from the atmosphere and holding it for an extended period of time. This study used the U.S. Forest …

Long-Term Effects Of Forestry Best Management Practices On Hydrology And Water Chemistry In Three Appalchian Headwater Catchments, Kameryn I. Wright

Theses and Dissertations--Biosystems and Agricultural Engineering

In 1982, a study was initiated in the Field Branch watershed, in the University of Kentucky’s Robinson Forest, to evaluate forestry best management practice (BMP) effectiveness after intensive harvesting. The study utilized a paired watershed approach on three adjacent Field Branch subcatchments. One subcatchment was left as the control, one had BMPs implemented (including a 50-ft undisturbed buffer along the stream), and one was clear-cut to the stream’s banks without the use of BMPs (i.e. logger’s choice). Prior research has shown that logging can negatively impact watershed functions by altering stream hydrology, geomorphology, water quality, and instream habitat. Thus, the …

Measuring The Adhesive Bond Quality Of Vinyl Ester-Glass Composites On Novolak Hmr Treated Wood, Leopold Eisenheld

Electronic Theses and Dissertations

The objectives of this research were to 1) reduce the drying time of novolak-based HMR coupling agent, 2) reinforce wood samples with E-glasslvinyl ester resin composite using the SCRIMPThq process, 3) evaluate the durability and strength properties of the FRP-wood composites, and 4) evaluate the bonding strength of wood-to-wood bonding using vinyl ester resin. To reduce the drying time of HMR-treated wood laminates, a randomized complete three factorial experiment was used to evaluate five HMR drying times, two HMR spread rates, and two HMR solids contents. The experiment evaluated the sensitivity of the HMR treatment process to accelerated drying. The …

Effects Of Strand Geometry On Selected Properties Of Long-Stand Structural Composite Lumber Made From Northeastern Hardwoods, Russell Edgar

Electronic Theses and Dissertations

Structural composite lumber (SCL) products often possess significantly higher design values than the top grades of solid lumber, making it a popular choice for both residential and commercial applications. The enhanced mechanical properties of SCL are mainly due to defect randomization and densification of the wood fiber, both largely functions of the size, shape and composition (species) of the wood element. Traditionally, SCL manufacturers have used thin, rectangular elements produced from either moderate density softwoods or low density hardwoods. Higher density hardwood species have been avoided, as they require higher pressures to adequately densify and consolidate the wood furnish. These …

Localization Of Expansin Expression During Adventitious And Lateral Rooting In Response To Auxin In Loblolly Pine, Fuyu Xu

Electronic Theses and Dissertations

Loblolly Pine is the most important and widely cultivated timber species in the southern United States. Due to its fast growth, it is extensively planted for lumber and pulpwood. Vegetative propagation will enhance gains from genetic improvement of tree species. Rooted-cutting is at present the most reliable non-somatic embryogenesis method for cloning specific genotypes. However, an abrupt decline of adventitious rooting capacity has hindered the application of vegetative propagation in loblolly pine. Unraveling the rooting mechanism may facilitate a way to overcome this barrier. Regulation of lateral and adventitious root formation by auxin has been demonstrated through the application of …

Evaluating The Durability Of Wood/Frp Bonds Through Chemical Kinetics Using A Range Of Mechanical Test Methods, Jonathan Philip Alexander

Electronic Theses and Dissertations

Hybrid composites of wood and fiber reinforced polymers (FRP) exhibit a flexibility of design properties through choices in fiber type, amount, orientation and resin type. With this flexibility comes the need to measure the durability of the composite material system, especially the bond between these two materials due to their markedly different responses to moisture. This study is two-fold; the first section examines methods for the mechanical testing and durability of wood/FRP laminations. Six mechanical tests were evaluated and a modified block shear method was identified as the most suitable due to its ability to provide representative results independent of …