Matching Items (579)
Description
The need for clean fuel sources is greater than ever, as fossil fuel dependence has soared and harmful emissions are being released into the atmosphere at increasingly higher rates. A viable solution to this issue is the use of microalgae for the creation of biofuels, as it holds a high concentration of lipids without requiring arable land for growth. This experiment studies downstream applications of microalgae, including how the extraction efficiency can be improved for greater lipid yield. 3-dimethyldodecylammonium propanesulfonate, myristyltrimethylammonium bromide and sodium dodecyl sulfate were used as surfactants to break down the algae cell walls and improve lipid recovery. The incubation times of the biomass in the surfactant were also studied at 0, 4.5, 24, 48 and 72 hours to more fully examine how surfactants affect the extraction of lipids. Along with this, hexane and isopropanol were used as the main extraction solvent in this experiment, but testing was done to compare these lipid yields to when ethyl acetate was used as the solvent. It was found that the MTMAB surfactant led to the greatest cell disruption, as its lipid yields were consistently higher than those of the other surfactants. Also, longer incubation times did improve the amount of lipid extracted, showing that the surfactants do have a strong effect on the cell breakdown. Finally, it was found that the ethyl acetate was a slightly more effective solvent than hexane and isopropanol in the conditions of this experiment. Overall, a stronger understanding of the wet extraction process was gained from these tests, as well as more insight into how some of the variables interact and work together during extraction.
ContributorsMartarella, Rebecca Lynne (Author) / Rittmann, Bruce (Thesis director) / Lai, Sean Yen-Jung (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
Biofuels are a carbon-neutral energy source proving to be a sustainable alternative to greenhouse gas-emitting fossil fuels that are accelerating the detrimental effects of anthropogenic climate change. A developing system aimed at more efficiently producing biofuels is called Microbial Electro-Photosynthesis (MEPS). In MEPS, a Synechocystis sp. PCC 6803 mutant lacking photosystem II (PSII) receives electrons by a hydroduroquinone (DQH2) mediator from a more efficient water-splitting electrochemical cell, rather than splitting water itself using PSII. However, growth of the Synechocystis cells prior to use in MEPS requires an organic carbon source, leading to internally-stored electron sources, namely glycogen, that compete with preferred DQH2 mediator-delivered electrons. In this study, the effects of organic carbon source (pyruvate, acetate, glucose, and no carbon source) and light condition (light or dark) on the physiology and P700+ reduction kinetics of photoheterotrophically grown Synechocystis mutants were studied with the hope of identifying a maintenance culturing method that allowed for both cell viability and mitigated glycogen storage. While no significant decreases in internal electron-sources were found with these methods, it was observed that Synechocystis cells fed pyruvate in the light had most successfully reduced competition between internal electron sources and preferred DQH2-delivered electrons. This study suggests that these experiments be re-run after removing exogenous carbon sources and that the nutrients available to the cells and their effects on pyruvate and acetate uptake be further investigated.
ContributorsMangus, Anna Michelle (Author) / Torres, Cesar (Thesis director) / Lewis, Christine (Committee member) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
Water scarcity is still an issue across the globe, so nonconventional desalination methods need to be developed to be able to get access to clean, safe water. One such method being studied is the pervaporation system, a membrane process that uses a vapor pressure differential to drive the system. There is a need to find the efficiency of the cold trap condenser that is used to collect the permeate so that a thermodynamic model can be fully developed to assist in the development of an industrial scale pervaporation system. An efficiency was not able to be confidently found, but it is believe to be between 95-100%.
ContributorsLuong, Kristina Jenny (Author) / Thomas, Mary Laura Lind (Thesis director) / Thomas, Elisabeth (Committee member) / Materials Science and Engineering Program (Contributor) / Chemical Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
In looking at genres of anime geared towards a male audience, the varying messages presented to Japanese men will be analyzed. Throughout this work it will be demonstrated that anime is used to both challenge and reinforce Japanese culture through human physical and family depictions, themes presented and expected masculine qualities aimed at a male audience.
ContributorsHattabaugh, Hunter David (Author) / Green, Heather (Thesis director) / Deacon, Deborah (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Ionic liquids boast a wide variety of application as modern electrolytes. Their unique collection of attributes, most notably insignificant vapor pressures, considerable ionic conductivity, and excellent thermal stability, prove ionic liquids excellent candidates for low-temperature electrolyte applications. This project focuses on the development of a low-temperature iodide-based ionic liquid electrolyte for a molecular electronic transducer (MET) seismometer. Based on ionic liquid 1-butyl-3-methylimidazolium iodide ([BMIM][I]), a functional electrolyte system is developed and optimized with addition of organic solvents, gamma-butyrolactone (GBL) and propylene carbonate (PC), and lithium iodide, showing the promise of operating at excessively low temperatures. The molecular interactions between [BMIM][I] and the organic solvents were classified using FTIR and 1H NMR spectroscopy. Specifically, the presence of hydrogen bonding between the carbonyl group on the organic solvents and the [BMIM]+ cation were captured. The effect of these interactions on several electrolyte properties were observed, including an extended glass transition temperature (Tg) of -120.2 °C and enhanced transport properties. When compared to the previous formulations, the optimized electrolyte exhibits a broader working temperature range, a higher fluidity over the temperature range from 25°C to -75 °C, and an enhanced ionic conductivity at temperatures below -70 °C as suggested by the Vogel–Fulcher–Tammann (VFT) model. Cyclic voltammetry (CV) confirmed the electrochemical stability of the electrolyte as well as the activity of the I3- / I- redox reaction for the MET sensing technology at room temperature. The presented works not only present a facile strategy of designing low-temperature electrolyte systems via design of molecular interactions, but also support future operations of MET seismometer.
ContributorsMacdonald, Shaun Michael (Author) / Dai, Dr. Lenore L. (Thesis director) / Lin, Wendy (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Do certain refugee groups better adapt and assimilate into society in Arizona? If this is the case, which factors contribute to this better rate of assimilation and what can other groups do to better assimilate into American society? Examining data from the Department of Economic Security and the Office of Refugee Resettlement, this study examined trends in refugee resettlement in Arizona. Specifically, trends involving socialization, employment, and education were examined. In addition to analyzing governmental data, this study involved the surveying of local refugees at random in order to gather data regarding the relationship between refugees' home countries and assimilation rates. This study finds evidence that there is indeed a correlation between refugees' geographical origin and their overall rate of assimilation. In order to determine this relationship, survey responses involving a variety of aspects of life in America were quantified. Specifically, this study showed that refugees from Latin America and the Middle East tend to assimilate better than those from Africa and other regions.
ContributorsLabban, Dillon Brendon (Author) / Mousa, Neimeh (Thesis director) / Sulayman, Umar (Committee member) / Chemical Engineering Program (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The purpose of this study was to determine if there was a relationship between the constructs of motivational theories, Self-Determination Theory and Health Belief Model, and adherence to a home exercise program. The constructs of Self-Determination Theory are autonomy, competence, and social relatedness. The constructs of Health Belief Model are perceived benefits, perceived barriers, perceived severity, and perceived susceptibility. Participants were receiving therapy at two outpatient clinics located in the Phoenix metropolitan area (n=40). Autonomy was assessed with a modified Treatment Self-Regulation Questionnaire. Competence was assessed with a modified Perceived Competence Scale. Social relatedness was assessed with a modified Health Care Climate Questionnaire. Perceived benefits and barriers were measured with a modified Exercise Benefits/Barriers Scale. Perceived severity and susceptibility were measured with a modified Health Beliefs Questionnaire. Adherence was measured with one Likert-type question that was created by the researchers. The data was scored and analyzed with the scoring guidelines provided by the questionnaires and the statistics software, IBM Statistical Package for the Social Sciences. The results showed that competence was the only construct that was significantly correlated with home exercise program adherence. The results from this study should be used for further research that focuses on creating a competence-supportive environment in physical therapy settings.
ContributorsAutrey, Makenna Noelle (Co-author) / Hamilton, Marissa (Co-author) / Hoffner, Kristin (Thesis director) / Broman, Tannah (Committee member) / School of Nutrition and Health Promotion (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
According to the Center for Disease Control, 1 in every 3 individuals will fall in their lifetime. Treadmill perturbation training has been a beneficial tool to increase reactive postural control and decrease the amount of falls. This study looked at the extent of the training effects on 29 healthy young adults to evaluate if stepping improvements in one direction could generalize to improvements in the quality of stepping in other directions. Outcome variables of Margin of Stability (MOS), step length, and step latency were evaluated for all 15 participants trained with forward perturbations and 14 participants trained with backward perturbations. From the paired t-tests, there were limited significant improvements in stepping with regards to motor learning and generalization. The only significant outcome was an increase in step length for the participants who trained in the backward direction (p=0.014; p<0.05). However, this significant increase in step length for this backward group did not generalize when the participants stepped in the forward direction post training. From the correlation tests, there was a significant, moderate correlation between motor learning and generalization (rho =0.527, p= 0.043; p<0.05), thus suggesting there may be a relationship between the amount of learning and the amount of generalization observed. Further evaluation of the second step and the foot motion during stepping may reveal more information and explain the changes in stepping to describe how healthy young adults were able to regain balance with each perturbation given.
ContributorsNowak, Rachael Teresa (Author) / Peterson, Daniel (Thesis director) / Dounskaia, Natalia (Committee member) / School of Nutrition and Health Promotion (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
Description
Current industrial production of petrochemicals releases CO2 as a byproduct into the
atmosphere, contributing to climate change. The sustainable alternative, microbial carbon
capture, has primarily focused on phototrophs that have naturally occurring carbon fixation
pathways, but are slow-growing, difficult to genetically engineer, and require sunlight, which
limits their large-scale production capacity. Using a heterotroph such as Escherichia coli allows for chemical production at high titers, rates, and yields (TRY) while being fast growing and easy to genetically engineer. Under fermentation conditions, the carboxylases in E. coli fix inorganic carbon in the reductive branch of the TCA cycle, producing industrially relevant chemical precursors such as succinate. However, the carboxylase’s access to CO2 is limited by the conditions surrounding it; most of the inorganic carbon inside the cell is in the form of
bicarbonate. Increasing the local concentration of CO2 near the carboxylase may improve the
kinetics of the pathway. To do this, a fusion protein that colocalizes carbonic anhydrase and
phosphoenolpyruvate carboxykinase (Pck) was created. However, since strains expressing this fusion protein did not grow above OD600 = 1 under fermentation conditions, further design optimization and investigation is needed.
ContributorsConway, Dalton (Author) / Nielsen, David (Thesis director) / Wang, Xuan (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2024-05