Theses and Dissertations at Montana State University (MSU)
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Item Photonic applications of functionalized gold nanorods: progress towards nonlinear metamaterials(Montana State University - Bozeman, College of Letters & Science, 2016) Latterman, Ryan Eric Michael; Chairperson, Graduate Committee: Robert Walker; This dissertation contains one article of which Ryan Eric Michael Latterman is not the main author.Nonlinear processes are used to convert one color of laser light into another and are very useful to any research who needs multiple colors of light for basic research or commercial purposes. However, nonlinear processes are inherently very weak and require high input energy to utilize them. Using modeling, it was predicted that ordered arrays of gold nanorods (GNRs), acting as a metamaterial, could be used to fabricate a material that would exhibit field enhancement. Because nonlinear processes depend on the strength of the field in which they interact, enhancing the field strength while using the same amount of input power would make these processes much more efficient and useful. Progress towards these materials included the synthesis of GNRs and gold reactive polymers. These polymers were used to solubilize GNRs in organic solvents while also introducing attachment points for nonlinear chromophores. To study a material which resembled the one in our modeling predictions, flat gold and two dimensional arrays of gold nanopillars were functionalized with gold-reactive nonlinear organic chromophores and studied using sum frequency generation. It was found that flat gold samples functionalized with a nonlinear chromophore exhibited a tremendous SFG signal, but only in one input polarization configuration. However, gold nanopillar samples exhibited a significant SFG signal in both PPP and SSP polarization configurations. These data agree with our modeling results and indicate that the materials produced here have the potential to be used as a mirror-less optical parametric oscillator. Organic-soluble GNRs produced in this thesis were then used in an adjacent project to improve the efficiency of a diode-pumped solid state laser design. Nd:YAG lasers are routinely used to produced 1064 nm light by pumping at 808 nm with a semi-conductor diode laser. However, when 1064 nm light is reflected back into the laser cavity, a parasitic phenomenon called amplified spontaneous emission (ASE) occurs. ASE can be combatted by applying a material to the laser rod that absorbs at 1064 nm. GNRs were synthesized at a specific size to absorb at 1064 nm, solubilized in epoxy and applied to a Nd:YAG laser, increasing efficiency by almost two fold.Item Nanocomposites : a study of theoretical micromechanical behavior using finite element analysis(Montana State University - Bozeman, College of Engineering, 2009) Milliren, Eric Carlton; Chairperson, Graduate Committee: Christopher H. M. JenkinsCurrent research in nanotechnology has produced an increasing number of possibilities for advanced materials. Among those materials with potential advanced mechanical properties are fiber-reinforced composite laminates that utilize nanoscale fiber diameters. Through a combination of studying classic micromechanical models and modern computer-aided finite element analysis (FEA), the advantages for utilizing these nanofibers in advanced structural applications, such as space mirror backings, was investigated. The approach for modeling these composite structures was that of a Representative Volume Element (RVE). Using the program ABAQUS/CAE, a RVE was created with the goals of accurately comparing to the shear lag theory, effectively incorporating "interphase" zones that bond the constituents, and demonstrating effects of down-scaling fiber diameter. In this thesis, the progression of the ABAQUS model is thoroughly covered as it developed into a verified model correlating with the shear lag theory. The model produced was capable of utilizing interphase if desired, and was capable of off-axis loading scenarios. A MathCAD program was written in order to employ the published theoretical techniques, which were then compared to the FEA results for verification. The FEA model was found to work well in conjunction with the theory explored using MathCAD, after which the nanofiber FEA model showed some clear advantages over a conventional-sized model, specifically an increase in strength of the composite RVE. Finally, it was determined that the interfacial bonding strength plays a large role in the structure of the interphase zone, and thus the overall strength of the composite.Item Protein cage architectures for targeted therapeutic and imaging agent delivery(Montana State University - Bozeman, College of Letters & Science, 2006) Flenniken, Michelle Lynne; Chairperson, Graduate Committee: Trevor Douglas; Mark Young (co-chair)Protein cage architectures such as viral capsids, heat shock proteins, and ferritins are naturally occurring spherical structures that are potentially useful nanoscale platforms for biomedical applications. This dissertation work demonstrates the utility of protein cages including their use as therapeutic and imaging agent delivery systems. Protein cage architectures have clearly demarcated exterior, interior, and interface surfaces and their structures are known to atomic level resolution. This information is essential for the engineering of functionalized nanoparticles via both chemical and genetic modification. In the process of tailoring protein cage architectures for particular applications, fundamental information about the architectures themselves is gained. The present work describes endeavors toward the use of three different protein cage architectures, the Cowpea chlorotic mottle viral capsid (CCMV), a small heat shock protein (Hsp) architecture originally isolated from the hyperthermophilic archaeon Methanococcus jannaschii, and human H-chain ferritin, as cell-specific therapeutic and imaging agent delivery systems. Each protein cage is roughly spherical, but their sizes differ; CCMV is 28 nm in diameter, whereas Hsp and HFn are 12 nm in diameter.