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DOES NUTRITION KNOWLEDGE MODERATE THE ASSOCIATION BETWEEN PERFECTIONISM AND EATING DISORDER SYMPTOMATOLOGY?
Title
DOES NUTRITION KNOWLEDGE MODERATE THE ASSOCIATION BETWEEN PERFECTIONISM AND EATING DISORDER SYMPTOMATOLOGY?
Creator
Schwartz, Natalie
Date
2017, 2017-05
Description
The trait of perfectionism is a psychological factor linked with the development of disordered eating, though the relation is unclear with...
Show moreThe trait of perfectionism is a psychological factor linked with the development of disordered eating, though the relation is unclear with some studies pointing to perfectionism as a predictor of eating disorder symptoms, while other studies have failed to find a statistically significant association. These discrepant findings suggest a need for understanding other factors that could be impacting the association. Research has suggested that individuals with eating disorders perform better than controls on knowledge of sources of nutrients and that while individuals with eating disorders spend more time reading about nutrition, this knowledge tends to be selective and skewed towards the aspects that maintain the eating disorder. The current study aimed to investigate the role of nutrition knowledge as a factor that may significantly influence the association between perfectionism and disordered eating attitudes. College women (N=122) completed several questionnaires related to disordered eating, nutrition knowledge, and perfectionism. The main research questions were: 1) whether perfectionism was related to disordered eating attitudes, 2) whether nutrition knowledge was related to disordered eating attitudes, and 3) whether nutrition knowledge moderated the relation between perfectionism and disordered eating attitudes. Results supported a positive association between perfectionism and disordered eating attitudes, in line with previous research. Despite a non-significant association between nutrition knowledge and disordered eating attitudes, there was found to be trend level significance (p<.07) for one moderation model. Specifically, the model assessing overall body dissatisfaction accounted for 33.34% of the variance, with a significant main effect for the level of perfectionism,suggesting the greater the degree of perfectionism traits, the greater the level of body dissatisfaction. While more research is needed to further develop an understanding of the link between perfectionism and disordered eating, nutrition knowledge is one possible avenue to explore in order to develop more effective prevention and intervention efforts.
M.S. in Psychology, May 2017
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INVESTIGATION OF ANION EXCHANGE MEMBRANES FOR ELECTROCHEMICAL ENERGY CONVERSION AND STORAGE SYSTEMS
Title
INVESTIGATION OF ANION EXCHANGE MEMBRANES FOR ELECTROCHEMICAL ENERGY CONVERSION AND STORAGE SYSTEMS
Creator
Wang, Lihui
Date
2017, 2017-05
Description
The alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N-...
Show moreThe alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N- dimethylhexylammmonium (DMH+) and trimethylammonium (TMA+) cation groups were investigated in poly (2,6- dimethyl 1,4-phenylene) oxide (PPO) and Udel® polysulfone (PSF) polymers. Previous studies have demonstrated that quaternary ammonium and phosphonium groups trigger backbone degradation in commercially available poly (arylene ether)-based AEMs, despite the base polymers’ resilience to alkaline solutions. Herein, I demonstrate that the electron withdrawing or donating character in the poly (arylene ether) backbone ultimately dictates whether the prepared AEMs will become brittle in alkaline media due to cation-triggered backbone degradation (Arges, Parrondo, Johnson, Nadhan, & Ramani, 2012a; Christopher G. Arges, Lihui Wang, Javier Parrondo, & Vijay Ramani, 2013). Mitigation of cation-triggered backbone degradation was only achieved when electron withdrawing substituents (not including the cation), such as sulfone or bromine, were eliminated from the polymer backbone (or, alternately, when electron donating groups were present). Hence, PPO AEMs prepared through chloromethylation, rather than free radical bromination, were resistant to backbone hydrolysis in alkaline media because each cation-functionalized repeat unit had two electron-donating methyl groups rather than a single methyl group. This study presents some design rules for preparing mechanically stable poly (arylene ether) AEMs from low cost, commercially available polymers for alkaline electrochemical devices.
Ph.D. in Chemical Engineering, May 2017
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Structural Studies of Degradation Mechanism of Lithium Rich Manganese, Nickel, and Iron Based Cathodes
Title
Structural Studies of Degradation Mechanism of Lithium Rich Manganese, Nickel, and Iron Based Cathodes
Creator
Aryal, Shankar
Date
2018
Description
Layered oxide compounds are superior with respect to discharge voltage and discharge specific capacity compared to other families of cathodes....
Show moreLayered oxide compounds are superior with respect to discharge voltage and discharge specific capacity compared to other families of cathodes. Therefore, LiCoO2 and LiMnxNiyCozO2, are the most commonly used cathodes since the commercialization of lithium ion battery. Recently, Li rich Ni, Mn, and Co oxide composite cathodes have been introduced with some improvements. As Co is toxic and expensive, attempts have been made to replace Co with cheap and environmentally friendly Fe. This dissertation reports that comparable discharge specific capacity and discharge voltage can be achieved by replacing Co with Fe and optimizing the composition of Mn, Ni, and Fe. However, the capacity and voltage fading on cycling are still remaining challenges. Structural change on electrochemical cycling is the main reason behind this fading. X-ray absorption spectroscopy (XAS), the specific element probe technique to study local structure and X-ray diffraction (XRD) to study the crystallographic phase information are utilized to understand the degradation/aging mechanism. A series of Li rich Mn, Ni, and Fe oxide composite cathode materials Li1.2Mn(0.30+x)Ni(0.40-x)Fe0.10O2 for x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25 were prepared using a sol-gel synthesis method. Rhombohedral and monoclinic crystal phases are found in Li rich Mn, Ni, and Fe composite oxide materials, but pure rhombohedral phase cannot be obtained without excess Li in the stoichiometric LiMO2 form. The pure monoclinic phase Li2MnO3 is also synthesized to confirm its presence in the composite oxide cathodes. Particle size and surface morphology are studied with scanning electron microscopy. The composite cathodes are cycled to over 100 cycles at 0.3C, for C = 250 mAhg-1 rate. XAS before and after 100 electrochemical cycles of Li rich Mn-Ni-Fe based cathodes is reported for the first time. The determination of fractional contents of monoclinic and rhombohedral phases in the composite oxide cathodes is not possible by powder XRD analysis, however, Li2MnO3 content decreases on decreasing Mn content and on increasing Ni content. The composition with higher Ni content has a higher degree of cation mixing. The synergistic effect of rhombohedral and monoclinic phases in Li rich Mn, Ni, and Fe based cathode is critical for stable electrochemical performance. The Li1.2Mn0.50Ni0.20Fe0.10O2 cathode showed the most stable cyclability performance (194 mAhg-1 first discharge capacity with 94 % capacity retention after 100 cycles at 0.3C rate) however, Li1.2Mn0.40Ni0.30Fe0.10O2 (220 mAhg-1 first discharge capacity with 57 % capacity retention) and Li1.2Mn0.55Ni0.15Fe0.10O2 (241 mAhg-1 first discharge capacity with 68 % capacity retention) cathodes showed higher 1st discharge capacity but poor cyclability under the same charge/discharge cycling.The XAS at Mn K-edge is used to explain the mechanism of Li2MnO3 activation for the improved electrochemical performance of Li rich Mn, Ni, and Fe oxide composite cathode, however Li2MnO3 contributed differently in different compositions. Synchrotron XRD and XAS measurements probed the lattice size expansion, which decreases the chemical potential of Li ions in the cathode on cycling leading to lower discharge voltage after cycling.
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