(9,521 - 9,540 of 10,081)
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Title
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Investigation of Novel Solid Polymer Electrolytes and Lithium Salts for Rechargeable Lithium Batteries
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Creator
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Zhao, Wendy
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Date
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2021
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Description
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Lithium-ion batteries (LIBs) are extensively used in many consumer electronic products. LIBs have great potential for application in electric...
Show moreLithium-ion batteries (LIBs) are extensively used in many consumer electronic products. LIBs have great potential for application in electric vehicles by virtue of their high power density and charge cycles. Research and development in this area has been focused on all around the globe. The major challenges include high cost, safety issues of the solvent based electrolytes, and low conductivities at ambient temperature of the solid polymer electrolytes (SPEs).This dissertation describes four novel electrolyte systems and a series of low lattice energy lithium salts synthesized and characterized for applications in LIBs. First, a new SPE has been derived from oligomeric poly(ethylene oxide) (PEO)-grafted crosslinked polystyrene (XPS) microspheres containing 1-2 lithium sulfonate moieties. This SPE possesses amorphous character with a glass transition temperature (Tg) around 135 ºC, displayed a good electrochemical stability with excellent ionic conductivity in excess of 10^-4 S/cm at 25ºC, and no significant thermal decomposition until 420 ºC. Second, a hybrid composite polymer electrolyte (CPE) was constructed with a gel matrix formed through hydrogen bonding by incorporating nanoparticles of fumed silica into the nanoscale network of PEO-XPS. Fumed silica with large surface modification group like polysiloxane formed an ideal gel structure offering significant high mechanical strength above 10^4 Pa, and a good ionic conductivity at 25°C. Third, a nonvolatile x-linked gel membrane electrolyte was synthesized with amino methacrylate, to introduce hemi-labile ligands as ionic liquid, into the polymer network. This new material exhibited improved salt solubility and ionic conductivity, due to the fast ligand exchange that facilitates the lithium ion structural transport, and also displayed an excellent electrochemical stability(4.8 V vs, Li/Li+). Fourth, a self-healing and thermal reversible polymer electrolyte designed based on Diels-Alder conjugation between multi-maleimides (2M-3M) and multi-furans (2F-4F) was synthesized. The reversible x-linking was realized through Diels-Alder (DA) and Retro-DA reactions by applying heating (>130°C)/cooling (<90°C) cycles. Last, new lithium salts with star and branch structures containing 1-4 of imide or methide moieties were synthesized and evaluated in PEO electrolyte system. These salts demonstrated good ambient temperature ionic conductivity at low concentrations, and the electrochemical stabilities were equal to or better than the most commonly used lithium salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).
Synthesis and characterization, including electrochemical properties, thermal and electrochemical stabilities, mechanical behaviors and surface morphologies of these new materials are described and discussed.
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Title
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Using population-level data to examine between-group health differences among transgender and cisgender United States military veterans
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Creator
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Woodward, Honor
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Date
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2021
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Description
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Some subgroups of military veterans, including those with marginalized identities, may be especially vulnerable to poor health. This...
Show moreSome subgroups of military veterans, including those with marginalized identities, may be especially vulnerable to poor health. This hypothesis is supported by the Minority Stress Theory framework, which posits that disparities in health can be attributed to the stress that minority individuals experience as a result of discrimination, prejudice, and oppression (Meyer, 1995; Meyer, 2003). A specific, potentially marginalized group of veterans that is under-explored regarding health is transgender veterans. Using data from the 2019 U.S. Behavioral Risk Factor Surveillance System (BRFSS), the current study hypothesized that transgender U.S. military veterans will report worse health than cisgender U.S. military veterans. Using case control matching, groups of transgender veterans (n = 124) and cisgender veterans (n = 104) were compared on several population-relevant health outcome measures. Chi-square tests of independence were conducted to test for significant differences between transgender and cisgender military veterans on the likelihood of experiencing certain health conditions, engaging in certain health behaviors, and utilizing health care services. Independent samples t-tests were used to test continuous health outcomes, such as self-reported mental health, physical health, and access to health care services. Gender identity was significantly associated with only one health outcome variable, with transgender veterans being more likely than cisgender veterans to have received a formal depression diagnosis (p = .01, phi = .17). No significant differences emerged between transgender and cisgender veterans on continuous health outcome variables. This suggests that previous literature on health disparities between transgender and cisgender individuals may not be generalizable to transgender veterans.
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Title
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Home Run!! (Bill's Blast-Off)...
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Date
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1997-09
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Description
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Hand-colored laser print of the outfield fence, bleachers, and scoreboard at Comiskey Park in Chicago. Drawn originally in August 1982, hand...
Show moreHand-colored laser print of the outfield fence, bleachers, and scoreboard at Comiskey Park in Chicago. Drawn originally in August 1982, hand colored in September 1997.
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Collection
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Robert Philip Gordon papers, 1963-2010
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Title
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Groundbreaking for Engineering building, Illinois Institute of Technology, Chicago, Illinois, August 29, 1966
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Date
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1966-08-29
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Description
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Photograph of the groundbreaking ceremony for the Engineering building known as Engineering 1 from its construction until 2015, now known as...
Show morePhotograph of the groundbreaking ceremony for the Engineering building known as Engineering 1 from its construction until 2015, now known as John T. Rettaliata Engineering Center. Pictured are Dr. John T. Rettaliata, Maynard P. Venema, Dr. Ralph G. Owens, and Axel A. Hofgren. Photographer unknown.
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Collection
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Office of Communications and Marketing photographs, 1905-1999
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