Barrett, The Honors College Thesis/Creative Project Collection

Enzyme-induced carbonate precipitation (EICP) is a biocementation technique that produces comparatively fewer carbon dioxide emissions than traditional cementation. However, the use of synthetic reagents for EICP is costly, and the process produces an ammonium byproduct which is a harmful pollutant. This study utilizes fresh urine as a source of urea and calcium-rich zeolites as an ammonium adsorbent and a source of calcium ions for the EICP cementation technique. Batch hydrolysis and adsorption experiments were conducted to determine the effects of zeolite type, zeolite form, and solution composition on ammonium adsorption and calcium release. Cementation experiments were then conducted to determine the effects of different hydrolysis and adsorption times on ammonium adsorption and calcium carbonate precipitation. The results showed that calcium-rich chabazite could be used as a source of calcium ions and as an effective adsorbent of ammonium for EICP. Additionally, synthetic, fresh urine and real, fresh urine had comparable ammonium adsorption and calcium release trends. Finally, inclusion of a pre-hydrolysis step reduced the ammonium adsorption and calcium release, but longer adsorption times lead to calcium carbonate precipitation outside of the sand column, which is an undesirable outcome for soil biocementation; even with this limitation, the calcium carbonate content of sand columns ranged from 0.48% to 0.92%, which signifies the potential of the proposed process for cementation, given a higher initial concentration of urea.

Automated vehicles are becoming more prevalent in the modern world. Using platoons of automated vehicles can have numerous benefits including increasing the safety of drivers as well as streamlining roadway operations. How individual automated vehicles within a platoon react to each other is essential to creating an efficient method of travel. This paper looks at two individual vehicles forming a platoon and tracks the time headway between the two. Several speed profiles are explored for the following vehicle including a triangular and trapezoidal speed profile. It is discovered that a safety violation occurs during platoon formation where the desired time headway between the vehicles is violated. The aim of this research is to explore if this violation can be eliminated or reduced through utilization of different speed profiles.

This study investigated the difference in biofilm growth between pristine polypropylene microplastics and aged polypropylene microplastics. The microplastics were added to Tempe Town Lake water for 4 weeks. Each week the microplastic biofilms were quantified. Comparing the total biofilm counts, the results showed that the aged microplastic biofilms were larger than the pristine each week. By week 3 the aged microplastic counts had almost doubled in size increasing from 324 to 626 Colony Forming Units per gram in just one week. There was a significant difference in the diversity found from week 1 to week 4. About 40% of the diversity for the pristine microplastic biofilm was seen as light-yellow dots and about 60% of these dots were seen on the aged microplastic biofilms in both weeks. As the microplastics were submerged in the lake water, new phenotypes emerged varying from week 1 to week 4 and from pristine to aged microplastic biofilms. Generally, it was found that as the microplastics stay in the environment there is more biofilm on the particles. The aged microplastics have a larger amount of biofouling, and the pristine microplastic biofilms were found to have more diversity of phenotypes.

The environment today is facing concerns over accumulation of plastics in landfills as well as excessive CO2 emissions. Containers and packaging take up approximately 15 million tons each year, and accumulations such as the Great Pacific Garbage Patch are entering the oceans. Work has been done to alter and treat polyethylene plastic to be added to cement mixtures. This is done to increase bearing capacity and ductility of concrete in addition to decreasing carbon emissions and plastic waste.

The concept of rape has been a prominent part of historical U.S. criminal law, and legislation and statutes have changed significantly over time. Despite numerous reforms, however, there is still a lack of reporting, arrests, and convictions for sexual assault cases. This is due to several factors influencing the judgement of criminal justice actors, such as how cases are handled by police officers and prosecutors, who decide whether to further investigate a case, send the case to prosecution for sentencing, or bring the case to trial. Some of these influences include legal and extra-legal factors and certain beliefs or assumptions about sexual assault victims, which affect these officials’ discretionary decisions. As a result, criminal justice officials tend to dismiss or unfound a sexual assault case, especially with acquaintance rape, contributing to the substantial lack of arrests and convictions. These facts, which are examined in the paper, emphasize the need to reassess our criminal justice system's current response to sexual assault cases. This includes adjusting the evaluation markers for prosecutors, improving the communication between the relevant criminal justice actors, and implementing evaluations of prosecutorial ethics and community satisfaction.

This thesis investigates the feasibility of using recycled ceramics as the aggregate in concrete, as an alternative to natural rock aggregates. The study evaluates the mechanical properties of concrete made with recycled ceramics and compares them with those of traditional concrete. The research involved laboratory experiments to determine compressive strength and displacement. The results show that the concrete made with recycled ceramics exhibited higher compressive strength and lower maximum displacement than traditional concrete, which means it acted more brittle. However, when the recycled ceramics were used to replace only 50% of the rock aggregate, the compressive strength decreased while the maximum displacement stayed the same, though the study concludes that a larger sample size is needed for more reliable results. Based on the findings, the thesis concludes that while the use of recycled ceramics in concrete may not be suitable for structural concrete, it could still have potential as a sustainable building material in non-structural applications.

Stoicism is a philosophy that emerged in the Hellenistic Age, between 323 BCE and 30 BCE in the Eastern Mediterranean and Middle East (Irvine, 2009). Stoicism was born into an exceptionally transitional social and political time period, and three major philosophers, Marcus Aurelius, Seneca, and Epictetus, rose to fame and established this manner of interacting with the world around them. These teachings and writings, still read throughout the world today due to their practicality and effectiveness, provide a major framework for “(It is [Stoicism]) the power of the mind to be unconquerable,” (Seneca, The Stoic Letters). Stoicism can be used as a tool in the pursuit of perseverance, wisdom, self control, and self mastery, which can ultimately lead to a more fulfilling and happy life. This philosophy is a practical one, and is designed with the intention to help those who practice it live well rather than just provide a theoretical understanding of the teaching of the world. Stoicism is a way to interact with others and the world in a way that reduces the amount of suffering experienced and can increase the capacity for joy. As a high achieving college student, it may not be feasible or entirely practical to live as Stoics did in the ancient world. Yet, aspects of ancient Stoicism can still be applied to modern-day living and can be used to make college students more resilient, happier, and allow them to live a fuller, more satisfied life. In this 7 week asynchronous program designed for high achieving college students, we will explore the most common barriers to happiness that college students face and explore what Stoic philosophies offer to help remedy these barriers.