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College and university campuses can play an important role in a student’s life, and campus outdoor spaces have the ability to positively impact various aspects of student health and well-being. It has long been understood that natural environments can promote health and well being, and in recent years research has

College and university campuses can play an important role in a student’s life, and campus outdoor spaces have the ability to positively impact various aspects of student health and well-being. It has long been understood that natural environments can promote health and well being, and in recent years research has begun to examine the impact of parks and landscapes in urban settings on subjective well-being (SWB). Subjective well-being (aka “happiness”) refers to
one’s self-reported measure of well-being and is thought of as having a high level of positive affect, low level of negative affect, and high degree of life satisfaction (Diener, 1984).

This study was conducted to assess the interrelationships between affective experiences, SWB, and usage of campus outdoor spaces in order to learn how outdoor spaces on the Arizona State University (ASU) Tempe campus can be enhanced to increase SWB and usage. In total, 832 students completed a survey questionnaire 1,140 times for six campus outdoor spaces. The results showed that students experience the greatest amount of happiness in the Secret Garden
and James Turrell ASU Skyspace, relaxation/restoration is the affective experience most strongly related to SWB, and SWB is negatively correlated with frequency of visits but positively link with duration of visits. To improve student happiness and usage of outdoor spaces on campuses, planners and designers should work on increasing the relaxing/restorative qualities of existing
locations, creating new spaces for relaxation/restoration around campus, reducing the perception of crowding and noise in large spaces, increasing fun/excitement by adding stimuli and/or opportunities for activity and entertainment, and adding equipment necessary for students to perform the activities they want. In addition to the ASU Tempe campus, the methodology and
findings of this research could be used to improve outdoor spaces on other college and university campuses and other types of outdoor environments.
ContributorsDavis, Kara (Author) / Cheng, Chingwen (Thesis director) / Cloutier, Scott (Committee member) / School of Sustainability (Contributor) / Dean, W.P. Carey School of Business (Contributor) / The Design School (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description

Lithium ion batteries are quintessential components of modern life. They are used to power smart devices — phones, tablets, laptops, and are rapidly becoming major elements in the automotive industry. Demand projections for lithium are skyrocketing with production struggling to keep up pace. This drive is due mostly to the

Lithium ion batteries are quintessential components of modern life. They are used to power smart devices — phones, tablets, laptops, and are rapidly becoming major elements in the automotive industry. Demand projections for lithium are skyrocketing with production struggling to keep up pace. This drive is due mostly to the rapid adoption of electric vehicles; sales of electric vehicles in 2020 are more than double what they were only a year prior. With such staggering growth it is important to understand how lithium is sourced and what that means for the environment. Will production even be capable of meeting the demand as more industries make use of this valuable element? How will the environmental impact of lithium affect growth? This thesis attempts to answer these questions as the world looks to a decade of rapid growth for lithium ion batteries.

ContributorsMelton, John (Author) / Brian, Jennifer (Thesis director) / Karwat, Darshawn (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description
Lithium conducting garnets in the family of Li7La3Zr2O12 (LLZO) are promising lithium conductors for solid-state batteries, due to their high ionic conductivity, thermal stability, and electrochemical stability with metallic lithium. Despite these advantages, LLZO requires a large energy input to synthesize and process. Generally, LLZO is synthesized using solid-state reaction

Lithium conducting garnets in the family of Li7La3Zr2O12 (LLZO) are promising lithium conductors for solid-state batteries, due to their high ionic conductivity, thermal stability, and electrochemical stability with metallic lithium. Despite these advantages, LLZO requires a large energy input to synthesize and process. Generally, LLZO is synthesized using solid-state reaction (SSR) from oxide precursors, requiring high reaction temperatures (900-1000 °C) and producing powder with large particle sizes, necessitating high energy milling to improve sinterability. In this dissertation, two classes of advanced synthesis methods – sol-gel polymer-combustion and molten salt synthesis (MSS) – are employed to obtain LLZO submicron powders at lower temperatures. In the first case, nanopowders of LLZO are obtained in a few hours at 700 °C via a novel polymer combustion process, which can be sintered to dense electrolytes possessing ionic conductivity up to 0.67 mS cm-1 at room temperature. However, the limited throughput of this combustion process motivated the use of molten salt synthesis, wherein a salt mixture is used as a high temperature solvent, allowing faster interdiffusion of atomic species than solid-state reactions. A eutectic mixture of LiCl-KCl allows formation of submicrometer undoped, Al-doped, Ga-doped, and Ta-doped LLZO at 900 °C in 4 h, with total ionic conductivities between 0.23-0.46 mS cm-1. By using a highly basic molten salt medium, Ta-doped LLZO (LLZTO) can be obtained at temperatures as low as 550 °C, with an ionic conductivity of 0.61 mS cm-1. The formation temperature can be further reduced by using Ta-doped, La-excess pyrochlore-type lanthanum zirconate (La2Zr2O7, LZO) as a quasi-single-source precursor, which convert to LLZTO as low as 400 °C upon addition of a Li-source. Further, doped pyrochlores can be blended with a Li-source and directly sintered to a relative density up to 94.7% with high conductivity (0.53 mS cm-1). Finally, a propensity for compositional variation in LLZTO powders and sintered ceramics was observed and for the first time explored in detail. By comparing LLZTO obtained from combustion, MSS, and SSR, a correlation between increased elemental inhomogeneity and reduced ionic conductivity is observed. Implications for garnet-based solid-state batteries and strategies to mitigate elemental inhomogeneity are discussed.
ContributorsWeller, Jon Mark (Author) / Chan, Candace K (Thesis advisor) / Crozier, Peter (Committee member) / Sieradzki, Karl (Committee member) / Arizona State University (Publisher)
Created2021
Description

An exploration of green spaces in urban environments, the mental health impacts of these spaces, and the successfulness of their integration into the city fabric. This project culminates in a video that compares a nature walk through an urban environment to a walk through an urban park.

ContributorsVan Buren, Gabriella (Author) / Underhill, Michael (Thesis director) / Hejduk, Renata (Committee member) / Barrett, The Honors College (Contributor) / The Design School (Contributor)
Created2022-05
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ContributorsVan Buren, Gabriella (Author) / Underhill, Michael (Thesis director) / Hejduk, Renata (Committee member) / Barrett, The Honors College (Contributor) / The Design School (Contributor)
Created2022-05
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ContributorsVan Buren, Gabriella (Author) / Underhill, Michael (Thesis director) / Hejduk, Renata (Committee member) / Barrett, The Honors College (Contributor) / The Design School (Contributor)
Created2022-05