Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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Capsaicin and dihydrocapsaicin account for 90% of capsaicinoids when it comes to the pungency of peppers. Capsaicin stability was investigated through a cooking and storage parameter where three different tests were done; cooking duration, cooking temperature, and storage stability. The concentration of capsaicinoids was quantified through gas chromatography-mass spectrometry where those values were then used to determine the total Scoville heat units (SHU). Furthermore, half-life was determined by finding the decay rate during cooking and storage. Results showed that there was an increase in degradation of capsaicinoids concentration when peppers were cooked for a long period of time. Degradation rate increases with increasing temperatures as would be expected by the Arrhenius equation. Hence, if a maximum pungency is wanted, it is best to cook the least time as possible or add the peppers towards the end of the culinary technique. This would help by cooking the peppers for a short period of time while not being exposed to the high temperature long enough before significant degradation occurs. Lastly, the storage stability results interpreted that a maximum potency of the peppers can be retained in a freezer or refrigerator opposed to an open room temperature environment or exposure from the sun. Furthermore, the stability of peppers has a long shelf life with even that the worse storage condition's half-life value was 113.5 months (9.5 years). Thus, peppers do not need to be bought frequently because its potency will last for several years.
ContributorsBustamante, Krista Gisselle (Author) / Cahill, Thomas (Thesis director) / Sweat, Ken (Committee member) / Armendariz Guajardo, Jose (Committee member) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
The spread of urbanization leads to habitat fragmentation and deterioration and changes the composition of ecosystems for species all over the world. Different groups of organisms are impacted differently, and insects have experienced loss in diversity and abundance due to changing environmental factors. Here, I collected seed beetles across 12 urban and rural sites in Phoenix, Arizona, to analyze the effects of urbanization and habitat variation on beetle diversity and abundance. I found that urbanization, host tree origin, and environmental factors such as tree diversity and density had no impact on overall beetle diversity and abundance. Beetles were found to have higher density on hosts with a higher density of pods. In assessing individual beetle species, some beetles exhibited higher density in rural sites with native trees, and some were found more commonly on nonnative tree species. The observed differences in beetle density demonstrate the range of effects urbanization and environmental features can have on insect species. By studying ecosystem interactions alongside changing environments, we can better predict the role urbanization and human development can have on different organisms.
ContributorsPaduano, Gabrielle (Author) / Savalli, Udo (Thesis director) / Sweat, Ken (Committee member) / Division of Teacher Preparation (Contributor) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Through the months September-November of 2017 a study was conducted to determine if bees prefer the sunflower, Helianthus annuus, native to Arizona, or a cultivar Helianthus sunflower in an urban environment. The study was executed in a small, controlled urban environment on Arizona State University West campus. Seven identified bee species and forty-nine specimens were collected, of the forty-nine specimens, two bees were reported on the Helianthus cultivar supporting native floral host preferences of native species. Variables such as nectar, pollen, floral color, and floral height were not measured, however, when the floral host genus was maintained wild bees visited the native Helianthus host significantly more yielding a supportive two-tailed p-value of 2.97x10-5. Three trends were identified in correlation with the experiment: 1) Bees foraged on native Helianthus annuus over the Helianthus cultivar, 2) Generalist species were more abundant than specialists on the Helianthus annuus, 3) Honey bees (Apis mellifera) were the most abundant species present. While not considered a trend, low floral diversity and abundance may explain the low diversity of bee species observed on the Helianthus. Floral host and pollinator desynchronization may also have affected bee diversity and abundance. Analysis of bee abundance and diversity support that wild bees may prefer native floral hosts over cultivar floral hosts when the floral genus, temperature, and time was controlled for in an urban environment.
ContributorsDunham, Jocelen Michaela (Author) / Foltz-Sweat, Jennifer (Thesis director) / Sweat, Ken (Committee member) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
Traditionally, forensic palynology, a branch of forensic botany, has been utilized during the investigation of crimes to link a suspect or victim to a particular place. This is done by identifying pollen and spores collected from objects, clothing, and/or bodies and comparing the identification to the plants documented at the scene of a crime. Pollen and spores both, as a form of trace evidence, can be identifiable through analysis of their morphology and have been documented to be resistant to destruction. It is also documented that criminals are willing to tamper with evidence to hinder criminal investigations, in the hopes of preventing or delaying their identification. Determining whether pollen evidence can be recovered from clothing evidence that has been tampered with would be a boon to forensic palynology, and the field of forensic botany as a whole. Two relatively common methods of tampering with clothing evidence include washing the clothing and destroying it by burning. With this in mind, this study was designed to determine whether pollen evidence can persist through the washing and/or the burning of clothing evidence by criminals attempting to obstruct justice and remain on the streets. Based upon previous documentation and experimentation, it was expected that any pollen or spores collected on clothing would persist through burning and continue to be identifiable. It was also expected that washing would remove a majority of pollen or spores present, if not all of them, and prevent linking the owner of the clothes to a particular crime scene. While this research would benefit from continued experimentation over a longer period of time, it shows that pollen evidence could be recovered from evidence that has been tampered with and identified as is usually done in a forensic palynological analysis. The form of tampering resulting in the highest chances of recovering palynological evidence utilized in this study was demonstrated to be burning, as washing resulted in no observation of pollen.
ContributorsRolls, Michaela Jeanet (Author) / Sartorio, Adriana (Thesis director) / Sweat, Ken (Committee member) / School of Mathematical and Natural Sciences (Contributor) / School of Humanities, Arts, and Cultural Studies (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Honey bees are vital to human society due to their pollination services but are currently under threat due to various factors. In order to avoid drastic declines in bee populations, it is important to fully understand factors that contribute to pollinator health and efficiency. The focus of this experiment were UV markings, commonly referred to as nectar guides. While various studies have found nectar guides to influence pollinator activity, relatively few experiments have been conducted to see how UV patterns and/or UV coverage of nectar guides affects bee foraging, which is what our experiment attempted to explore. Our hypothesis was that UV coverage has a positive impact on bee foraging activity, but that full UV coverage would lower foraging activity, we also hypothesized that UV pattern would also influence foraging activity and that pollinators will prefer circular patterns. In our experiment we created artificial nectar dispensing flowers with differing UV markings and placed them out in a natural environment and recorded pollinator visitation. We then utilized a two-way ANOVA to determine if there was a statistical correlation between UV abundance and/or UV pattern on pollinator activity. Our results revealed no statistical correlation for either UV coverage (p = .389) nor UV pattern (p = .437) to pollinator activity. While no statistical correlation was found, graphical analysis of the mean between different UV groups revealed a noticeable flower preference was seen for flowers with at least some level of UV compared to no UV and a slight increase in activity for circular patterns compared to radial patterns. This suggests that perhaps UV abundance and pattern plays a minor role in pollinator activity but nothing that is statistically significant. We suggest further follow up research to improve and refine our methods and utilize a greater range of patterns and abundance size with a larger sample size to better understand the role UV pattern and UV coverage has on pollinator foraging activity.
ContributorsLazau, Joshua (Author) / Foltz-Sweat, Jennifer (Thesis director) / Sweat, Ken (Committee member) / School of Social and Behavioral Sciences (Contributor) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05