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Wood and Resin Composite Extrusion for Additive Manufacturing
No full textAdditive manufacturing is a quickly growing manufacturing technique with a multitude of applications. It has the ability to rapidly manufacturing geometries that other techniques cannot. Additionally, it produces very little waste material and can use recycled materials. Additive manufacturing is becoming popular in the building construction industry. Currently, concrete is the primary additive manufacturing material being used in the construction industry. Wood-based composites have yet to be used in additive manufacturing for the construction industry because a method to use high wood content composites in additive manufacturing has not been developed. This study details the development of a wood-based composite extrusions method for additive manufacturing. A screw extruder was designed and constructed that could extrude wood-based composites with high wood content. This extruder produced many composite samples of various wood element sizes and resin content that were then cured. The cured sample sets were tested using a 3-point bend test. Samples were oven cured at different temperatures and time periods. It was determined that the rate at which the samples were cured did not affect the bending properties of the composite. For a sample made with wood element size less than 40 mesh and cured for two days at 50°C, the bending strength and Young’s modulus were 24.7 MPa and 4.6 GPa respectively. These mechanical properties are relatively close to OSB and fiber board. Thus, the extruded wood-based composites are suitable to replace traditional composites based on strength and modulus performance. Capillary rheology was performed to test the properties of the wood-based composite during extrusion. A custom capillary rheometer was designed and fabricated to perform these tests. The viscosity of the composite was found to be non-Newtonian and shear-thinning. A power-law model was used to characterize the viscosity. The power-law model was then used in a CFD model to simulate the capillary rheology extrusion. The CFD model was able to simulate the extrusion pressure of the capillary rheometer within 1.6% error, compared to the experimental value.masters, M.S., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2021-0
Radiation Effects on Metal Fe and Core-Shell Ti-TiO2 Nanoparticles by Molecular Dynamics Simulation
No full textNanoparticles, due to their small size and radiation absorption property, are widely used in nano nuclear nanotechnology as well as radiation environment. Radiation-induced defects could negatively affect mechanical properties, potentially leading to accidents. In this study, the molecular dynamics (MD) method, as a powerful atomic-level simulation tool, is applied to investigate and characterize the formation and evolution of point defects in irradiated Fe nanoparticle (NP) and core-shell Ti-TiO2 NP by using a recent updated many-body interatomic potential. MD especially helps us gain access to length and time scales that are not accessible experimentally and learn more about the multi-scale phenomena that occur during the irradiation of nanomaterials. Computer simulations provide information at the microscopic level, acting as a bridge to the experimental observations and giving insights into processes that take place at small time and length scales. The increasing computer capabilities in combination with recently developed scalable codes, and the availability of realistic potentials set the stage to perform large scale simulations, approaching phenomena that take place at the atomistic and mesoscopic scale in a more realistic way. This dissertation has focused on understanding the atomic-level mechanism of irradiation damages and defect formations in Fe nanoparticle (NP) and core-shell Ti-TiO2 NP. To test the NPs compatibility for several neutron energy and temperature stability, a series of MD simulations have been done for Fe NP and core-shell Ti-TiO2 NP. The results from the simulation provide the defect orientation on NP after irradiation and can be used to predict the experimental results.doctoral, Ph.D., Physics -- University of Idaho - College of Graduate Studies, 2021-1
FUNGAL RESISTANCE AND LEACHABILITY OF GENIPIN-CROSSLINKED CHITOSAN TREATED WOOD
No full textAs a natural antimicrobial compound, chitosan (C) has been widely explored for wood protection against numerous deteriorating organisms and has proven its effectiveness. However, the application of chitosan as a biobased preservative has been significantly limited due to its high leachability from treated wood. Genipin is a biobased crosslinking agent that can crosslink with chitosan in very mild conditions. The objective of this study was to examine the decay resistance and leachability of genipin-crosslinked chitosan (GC) treated wood against common wood-decaying fungi. The formation of GC was confirmed using Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). The antifungal efficacy of GC against two brown-rot fungi, Gloeophyllum trabeum (G.t.) and Rhodonia placenta (R.p.) and two white-rot fungi, Trametes versicolor (T.v.) and Irpex lacteus (I.l.) was first determined using malt-gar as substrate, which revealed that GC inhibited the growth of all fungi studied and exhibited similar efficacy to those of C treatment levels. Micrographs from the light and fluorescence microscopy showed changes in fungi morphology and nuclei deformation due to the effect of GC. Upon impregnation, GC-treated wood samples show an increased retention and mass gain as the function of treating concentrations, which were as high as 21 kg/m2 and 3.6%, representatively. However, cross-linking chitosan with genipin did not reduce the leaching rate of chitosan. GC treated wood samples generally show a significantly lower mass loss than those of the control groups regardless of the leaching test.masters, M.S., Natural Resources -- University of Idaho - College of Graduate Studies, 2021-1
Design and Nuclear Criticality Safety Evaluation of the Fuel Salt Preparation and Handling Processes for the Molten Salt Nuclear Battery Design
No full textA Nuclear Criticality Safety Evaluation was performed for the proposed FLiNaK-UF4 fuel salt preparation and handling processes to be used in the Molten Salt Nuclear Battery concept. The fuel salt is a mixture of purified eutectic LiF-NaF-KF (respectively 46.5, 11.5, and 42 mole %) and UF4 fuel with a fuel loading of 18 mole % UF4 and enrichment of 19.75 mole % 235U. The DOE-STD-3007-2017 technical standard was followed while performing this evaluation to be compliant with the ANSI/ANS-8 series of criticality safety standards. The Monte-Carlo nuclear code Serpent 2, version 2.1.31, was used to perform the calculations for this evaluation to estimate the effective neutron multiplication factor, keff, of the processes under normal and credible abnormal conditions. The results of this evaluation show that the processes will remain subcritical under both normal and credible abnormal conditions by not exceeding an upper subcritical limit of 0.95. The maximum keff under normal conditions was 0.58737 ± 0.00085 (95 % confidence) during the transportation of the fuel salt vessels. The maximum keff under abnormal conditions was 0.82013 ± 0.00134. Any controls and assumptions used for these processes are discussed.masters, M.S., Nuclear Engineering -- University of Idaho - College of Graduate Studies, 2021-0
Regional Habitat Variation for Pygmy Rabbits
No full textThe pygmy rabbit (Brachylagus idahoensis) is a sensitive species endemic to the sagebrush steppe ecosystem of the western USA. As ecosystem engineers and sagebrush obligates, pygmy rabbits and their connection to sagebrush have made the species fascinating to study. In Idaho, federal and state agencies are currently focusing on conservation and restoration of sagebrush habitats, and for certain species like pygmy rabbits, information about their distribution and habitat relationships is incomplete. Sagebrush habitats available to pygmy rabbits across their range are diverse, and a better understanding of the characteristics that influence their presence is necessary for future conservation actions. This thesis investigates how habitat relationships of pygmy rabbits differ across five ecological regions in Idaho and how certain environmental characteristics influence habitat suitability. We modeled predicted species distribution for five distinct ecological regions in Idaho, identifying environmental characteristics that influence suitable habitat for the species, while also identifying areas of predicted suitable habitat within each region. We created inductive species distribution models (SDMs) using maximum entropy methods that included a suite of environmental predictor variables representing topography, vegetation, climate, and soil characteristics. Results of the regional models identified substantial variation in habitat associations across the five regions, with each retaining a unique set of environmental predictors. Bioclimatic variables were the most influential environmental parameters in all five regions, but the specific variables differed among all regions. The models that were developed at regional extents predicted smaller areas of habitat (an average of 15% less for suitable habitat and 80% less for primary habitat) than predictions generated from a model developed at the extent of the entire range of the species. Lastly, we projected the regional models using future climate scenarios to explore how future climate conditions might affect predicted suitable habitat for pygmy rabbits. Significant reductions in suitable habitat were projected across the study area, but variation among regions also was apparent. Although these projections should be interpreted with caution, they suggest that climate-driven changes in the environment could have large and varying effects on persistence of habitat for pygmy rabbits in Idaho.masters, M.S., Natural Resources -- University of Idaho - College of Graduate Studies, 2021-0
Creep Fatigue Crack Growth Behavior of Wrought and Additive Manufactured IN718 at Elevated Temperature
No full textThis study focuses on the fatigue crack growth, creep fatigue crack growth, and creep crack growth behavior of wrought and additive manufactured IN718 at 600oC. Task Group on Elevated Temperature Crack Growth (E08.06.05) initiated a round robin, ASTM Interlaboratory Study Program (ILS) assigned program number 1679, in validation of ASTM Standard E2760 using wrought IN718 compact tension specimens which were tested under fatigue crack growth and creep fatigue crack growth conditions with hold times of 0, 60 and 600 seconds. The study showed that for a hold time of 60s to an infinite hold time crack growth rate was independent of number of applied cycles and dependent on time. Additive manufactured (AM) compact tension specimens were also tested under similar conditions. The AM specimens were machined in three different orientations with respect to build direction and the results showed anisotropic behavior. Wrought and AM IN718 crack growth rates were compared and showed that for lower values of stress intensity the AM IN718 had lower crack growth rates but at higher values of stress intensity the AM IN718 material exhibited higher crack growth rates than the wrought IN718. Fracture surface analysis of wrought IN718 shows a transition from transgranular to intergranular fracture mode from the pre-crack to the creep fatigue crack growth region. The fracture surface of the various AM IN718 orientations did not resemble the fracture surface of the wrought IN718.masters, M.S., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2021-1
Indentation of Solid Nitrogen Between 30 K and 40 K
No full textThis research was completed in support of the proposed NASA mission, Triton Hopper, whose intended mission is to land on Triton, a moon of Neptune. Flight over Tritons surface is to be provided by repurposing in situ resources; where solidified nitrogen is gathered, heated, and used as a gaseous propellant. Mechanical property data of solid nitrogen at Triton surface conditions is almost nonexistent. A system was designed to gather hardness data via flat punch indentation of cryocooler formed solidified nitrogen samples. The system was used to collect data at temperatures between 30 and 40K at 1-degree increments. Hardness averages ranged from 0.35 Mpa to 2.26 Mpa as temperature decreased, the data were approximately 3 to 4 times harder than prior data. The system was modified and used to conduct rotary shear testing. Based on the results, suggestions for further work are provided.masters, M.S., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2021-1
Mesic Meadow Responses to Variation in Grazing Management Practices: Balancing Sage-Grouse Resources with Livestock Production
No full textMesic meadows across the arid western United States play an integral role in providing water and forage resources for wildlife and domesticated livestock. Greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse), a species of conservation concern, depend upon mesic meadows because they support key forb species of high nutritional importance to juveniles during late-brood rearing. Additionally, mesic meadows provide valuable forage and water resources to domesticated livestock, especially as summer progresses and adjacent upland vegetation begins to desiccate. Due to the limited geographic extent (masters, M.S., Natural Resources -- University of Idaho - College of Graduate Studies, 2021-0
FROM KURDISTAN TO LONDON AND NASHVILLE: IDENTITY NEGOTIATION AND THE EMERGENCE OF KURDISH CULTURAL IDENTITY IN DIASPORA
No full textThe Kurdish people are a unique ethnic group whose origins can be traced from the Zagros Mountains in ancient Media (864 BCE), migrating into what is now Turkey, Iraq, and Syria. From the sixth century (CE), Kurds have inhabited the ancient Mesopotamian plains and the highlands of southern Turkey. There are also significant populations of Kurds in Armenia, Germany, the United Kingdom, and the United States of America. For over 2000 years, Kurds have been in an almost perpetual state of conflict throughout the Middle East. In response to numerous incidents of genocide, sectarian violence, and cultural oppression, Kurdish migrants have fled their native lands in three consecutive waves, establishing diasporic communities in nations around the world. This thesis explores Kurdish identity in Kurdistan and within the diasporic communities of London, United Kingdom, and Nashville, Tennessee, U.S.A. Interviews with Kurdish emigrants from Iraq, Syria, Turkey, and Iran, combined with demographic and quantitative information obtained from an online questionnaire, suggest an identity negotiation that is both fractured and suppressed in Kurdistan; yet rediscovered and emergent in the comparative safety and freedom of diaspora.masters, M.A., Anthropology -- University of Idaho - College of Graduate Studies, 2021-1
Characterizing Antibody Escape Variants in the Respiratory Syncytial Virus Fusion Glycoprotein
No full textMonoclonal antibodies (mAbs) are becoming more commonly used as prophylactics or therapeutics for viral infections. While the binding specificity of the mAb may provide adequate protection against the wild-type virus, natural selection will favor viral genomes that acquire mutations leading to amino acid changes in viral proteins where mAbs normally bind. This results in a phenomenon known as antibody escape. This thesis project focuses on the mAb D25 and its interaction with the respiratory syncytial virus (RSV) fusion glycoprotein (F). F mediates viral entry into host cells and fusion between neighboring cells, while D25 neutralizes the ability of F to function in entry kinetics. However, F readily mutates to evade the neutralizing effects of mAbs including D25, resulting in variants that lead to antibody escape. A D25 mutational library encompassing 30 sites within the D25 binding epitope of F was built with the help of molecular modeling. We developed a high-throughput pipeline to screen these variants for antibody escape using methodologies such as deep mutational scanning and retroviral gene expression systems. Several individual variants within the D25 library were also assessed for antibody binding differences using flow cytometry and in-cell ELISA. Along with molecular modeling predictions of F mutations that give rise to antibody escape, our lab previously identified three mutations via deep sequencing after several passages of RSV in HEp-2 cells with varying concentrations of the D25 mAb. These mutations, Q202R, N208Y, and N208K were identified, where N208Y and N208K were both predicted by molecular modeling. This project allows for the identification and characterization of potential escape mutations in F by screening all potential amino acid variants at the 30 sites within the D25 binding epitope. We can use our findings to assist in viral variant surveillance for RSV, first using a broad deep mutational scanning – based screen to find potential escape mutants and then by validating those findings using individual-based binding assays.masters, M.S., Biology -- University of Idaho - College of Graduate Studies, 2021-0