Doctor of Philosophy, The Ohio State University, 2024, Materials Science and Engineering

Superwood is a densified, chemically altered form of wood that provides tensile strength similar to steel while having a lower density than aluminum. This material is lightweight and renewable, a promising alternative to many structural materials in areas such as the automotive industry looking to reduce their environmental impact. To truly make use of the material, it needs to be able to join to other materials such as aluminum. Two common methods of joining materials in the automotive industry are adhesive bonding and self-pierce riveting (SPR). Adhesive bonding of superwood with pre-existing adhesives requires testing of the effects of surface treatment on adhesive bonding and penetration. The densification of superwood alters the wood structure by collapsing vessels, reducing the ability of adhesive to penetrate into the surface as is common in bonding of natural wood. The compression also leads to a surface similar to burnished wood, further reducing wettability and penetration. Surface treatments and curing conditions were studied using lab-scale experiment and examined using SEM to address these issues. Self-pierce riveting is common in automotive bonding due to creating a strong mechanical bond without requiring pre-drilled holes that necessitate additional processing steps in assembly. Superwood is a natural composite as is natural wood, leading to risks of damage during the SPR process as fibers are separated by the rivet. Study was done on both lab scale testing and finite element modelling of the SPR process in LS-DYNA to determine the best parameters for riveting of superwood, such as rivet geometry, die geometry, and insertion speed. The quality of different joint preparations was determined by analysis of the cross-section geometry focusing on the rivet spread and minimum sheet thickness. These results were combined with adhesive bonding to find optimal conditions for rivbonded (riveted and adhesive) joints. Superwood was also tested for u (open full item for complete abstract)

Committee: Alan Luo (Advisor); Xun Liu (Committee Member); Jenifer Locke (Committee Member) Subjects: Materials Science

Master of Science, Miami University, 2014, Microbiology

Methanosarcina acetivorans is a methanogenic archaeon capable of utilizing monomethylamine (MMA), dimethylamine (DMA) and trimethylamine (TMA) for methanogenesis. The mtmP, mtbP, mttP1 and mttP2 genes were predicted to encode MMA, DMA, TMA and TMA permeases, respectively, based on their genomic context and bioinformatic analysis. We investigated the roles of these predicted permeases in growth on methylamines. The ΔmtmP, ΔmtbP, and ΔmttP1/ΔmttP2 deletion strains were created using a markerless genetic exchange method. Unaltered growth phenotypes of the mutants on their respective methylamines, except for an extended lag phase in the ΔmtmP mutant, suggest the respective substrates are still transported in the absence of the predicted permeases. These results could be due to broad substrate specificity of the permeases or due to alternative permease activity when grown in pure culture under laboratory conditions of substrate concentration. The ΔmtmP/ΔmtbP and ΔmtbP/ΔmttP1/ΔmttP2 deletion strains show some defect in DMA-dependent growth suggesting cross-reactivity between methylamine permeases.

Committee: Donald J. Ferguson Jr. (Advisor); Annette Bollmann (Committee Member); Gary R. Janssen (Committee Member) Subjects: Microbiology; Molecular Biology

Doctor of Philosophy, The Ohio State University, 2002, Chemical Engineering

Unsaturated polyester and vinylester resins are used in a wide variety of applications. These materials provide high structural stability, increased resistance to solvent and temperature, and improved mechanical stability. Low profile additives have been found highly effective in eliminating the polymerization shrinkage of unsaturated polyester resins in high temperature molding processes such as compression molding of SMC and injection molding of BMC. In recent years, the improvement focuses on the development of low temperature and low-pressure fabrication techniques, such as low temperature/low pressure SMC, RTM, SCRIMP, to significantly reduce the tooling cost. However, poor performance of low profile additives and high residual reactivity in low temperature molding processes unavoidably undermine further applications of unsaturated polyester and vinylester resins. Therefore, there is considerable potential for improving the process through greater technical understanding of reaction and volume shrinkage control mechanism in low temperature cure of unsaturated polyester and vinylester resins. An integrated analysis is carried out in this study to investigate the reaction kinetics and shrinkage control of unsaturated polyester or vinylester resins with low profile additives cured at low temperatures. A differential scanning calorimeter (DSC), a Fourier transform infrared spectrometer (FTIR), and a rheometrics dynamic analyzer (RDA) are used to study the reaction kinetics and rheological behaviors. A dilatometer is applied to study the volume change. A scanning electron microscopy (SEM) and an optical microscopy are employed to investigate the structure and morphology evolution during curing. The effects of curing agents including initiator, promoter, and comonomer on the low temperature polymerization are investigated. These experiments are designed to provide information regarding the polymerization mechanism and microstructure evolution throughout the free radi (open full item for complete abstract)

Committee: Li Lee (Advisor) Subjects:

Master of Music (MM), Bowling Green State University, 2012, Music Ethnomusicology

In this project, I studied the music used in Ultimate Fighting Championship (UFC) events and connect it to greater themes and aspects of social study. By examining the events of the UFC and how music is used, I focused primarily on three issues that create a multi-layered understanding of Mixed Martial Arts (MMA) fighters and the cultivation of identity. First, I examined ideas of identity formation and cultivation. Since each fighter in UFC events enters his fight to a specific, and self-chosen, musical piece, different aspects of identity including race, political views, gender ideologies, and class are outwardly projected to fans and other fighters with the choice of entrance music. This type of musical representation of identity has been discussed (although not always in relation to sports) in works by past scholars (Kun, 2005; Hamera, 2005; Garrett, 2008; Burton, 2010; Mcleod, 2011). Second, after establishing a deeper sense of socio-cultural fighter identity through entrance music, this project examined ideas of nationalism within the UFC. Although traces of nationalism fall within the purview of entrance music and identity, the UFC aids in the nationalistic representations of their fighters by utilizing different tactics of marketing and fighter branding. Lastly, this project built upon the above-mentioned issues of identity and nationality to appropriately discuss aspects of how the UFC attempts to depict fighter character to create a “good vs. bad” marketable binary. Although the UFC and its fighters vehemently craft and cultivate a specific projection of who and what they are, the ultimate goal is to convince and sell these projections to UFC fans. And as a result, fights often mark a conflict of not only two fighters, but two contrasting identities as well. In conclusion, it is my hope that the project I propose here will add to the canon of studies involving music and spectacle, and introduces to music scholarship a previously unexplored area within the (open full item for complete abstract)

Committee: Megan Rancier (Advisor); Kara Attrep (Committee Member) Subjects: Music

Master of Science (MS), Bowling Green State University, 2012, Applied Statistics (ASOR)

Latent Curve Analysis (LCA) is a statistical technique used for longitudinal studies that combines the methods of factor analysis with linear models. The purpose of LCA is to allow the modeler to combine common variables into a smaller number of random variables. The random variables are then regressed linearly to allow the modeler to express how the variables change over time. Due to the complexity of LCA, a researcher is forced to choose between a one growth curve model, or spend countless hours attempted to locate a better model. The purpose of this study is to create general methods that will allow future researchers the ability to create more adequate LCA models than the one growth curve model in a timelier manner. The data used for the thesis came from a longitudinal study dated 2000 to 2004. The study was a positive orientation survey that measured seven characteristics of positive orientation for 45 males and 81 female participants over three time periods. Using the program LISREL, a one growth curve LCA model was first analyzed by a group of researchers named Guido Alessandri, Gian Vittorio Caprara, and John Tisak. Using a variety approaches, a total four techniques were created in effort to solve the problem. Using a chi square test, two of the techniques resulted in models that were statistically significantly better than the one LCA model. These two models are discussed in detail within the paper. Though only two of the four techniques produced a better model than the one growth curve LCA model, each of the four methods could prove helpful for future researchers attempting to solve this problem.

Committee: Nancy Boudreau Dr (Advisor); John Tisak Dr (Committee Chair); Maria Rizzo Dr (Committee Chair) Subjects: Statistics

Doctor of Philosophy, University of Akron, 2005, Engineering

The polymer industry has become one of the fastest growing areas in the materials industry for several decades, and would be continue to do so in the foreseeable future. However, due to growing environmental and health concern, the polymer manufacturers have faced increasing pressure to apply environmentally benign technologies in order to accommodate tightened environmental regulations. In the process of searching for clean and low emission polymerization techniques, supercritical fluid technology and sonochemistry have attracted more and more interest because of their unique advantages over conventional techniques. The present study is to expand our knowledge of polymer synthesis processes involving supercritical fluid, sonochemistry and microemulsion technologies. This study included three affiliated projects as supercritical dispersion polymerization, ultrasonically initiated polymerization in near-critical environment and ultrasound assisted microemulsion polymerization in aqueous solution. The success of projects will significantly broaden the application potential for these advanced chemical processes in both conventional and unconventional systems. In the study of dispersion polymerization in scCO2, a new PDMS macromonomer has been successfully applied as surfactant to stabilize the polymerization process. The polymerization results indicated that the conversion is increasing with the increasing of stabilizer concentration, and the particle morphology become more uniform at the same time. In the study of ultrasound irradiation in high-pressure medium, it has been confirmed that sonication alone could initiate the polymerization process. The monomer: CO2 ratio and ultrasound irradiation time appeared to have impact on the molecular weight and its distribution of the polymeric products. Discrete morphology from SEM image suggested that the polymer particles could be stabilized without surfactant during the polymerization process. In the study of ultrasound ass (open full item for complete abstract)

Committee: Henry Cheung (Advisor) Subjects: Engineering, Chemical