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Surface Mechanical Attrition Treatment (SMAT) of 7075 Aluminum Alloy to Induce a Protective Corrosion Resistant Layer

Description

This paper investigates Surface Mechanical Attrition Treatment (SMAT) and the influence of treatment temperature and initial sample surface finish on the corrosion resistance of 7075-T651 aluminum alloy. Ambient SMAT was performed on AA7075 samples polished to 80-grit initial surface roughness.

This paper investigates Surface Mechanical Attrition Treatment (SMAT) and the influence of treatment temperature and initial sample surface finish on the corrosion resistance of 7075-T651 aluminum alloy. Ambient SMAT was performed on AA7075 samples polished to 80-grit initial surface roughness. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used to characterize the corrosion behavior of samples before and after SMAT. Electrochemical tests indicated an improved corrosion resistance after application of SMAT process. The observed improvements in corrosion properties are potentially due to microstructural changes in the material surface induced by SMAT which encouraged the formation of a passive oxide layer. Further testing and research are required to understand the corrosion related effects of cryogenic SMAT and initial-surface finish as the COVID-19 pandemic inhibited experimentation plans.

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2020-05

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In situ SEM Testing for Fatigue Crack Growth: Mechanical Investigation of Titanium

Description

Widespread knowledge of fracture mechanics is mostly based on previous models that generalize crack growth in materials over several loading cycles. The objective of this project is to characterize crack growth that occurs in titanium alloys, specifically Grade 5 Ti-6Al-4V,

Widespread knowledge of fracture mechanics is mostly based on previous models that generalize crack growth in materials over several loading cycles. The objective of this project is to characterize crack growth that occurs in titanium alloys, specifically Grade 5 Ti-6Al-4V, at the sub-cycle scale, or within a single loading cycle. Using scanning electron microscopy (SEM), imaging analysis is performed to observe crack behavior at ten loading steps throughout the loading and unloading paths. Analysis involves measuring the incremental crack growth and crack tip opening displacement (CTOD) of specimens at loading ratios of 0.1, 0.3, and 0.5. This report defines the relationship between crack growth and the stress intensity factor, K, of the specimens, as well as the relationship between the R-ratio and stress opening level. The crack closure phenomena and effect of microcracks are discussed as they influence the crack growth behavior. This method has previously been used to characterize crack growth in Al 7075-T6. The results for Ti-6Al-4V are compared to these previous findings in order to strengthen conclusions about crack growth behavior.

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2018-05

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Eat In, Not Out: A Comparative Analysis Between at Home Cooking and Restaurant Dining

Description

This creative project seeks to demonstrate the nutritional and financial benefits of cooking in versus eating out to college age students. We sought to determine what factors significantly differentiated restaurant meals versus home-cooked versions, and how we could share this

This creative project seeks to demonstrate the nutritional and financial benefits of cooking in versus eating out to college age students. We sought to determine what factors significantly differentiated restaurant meals versus home-cooked versions, and how we could share this information with our peers to potentially influence them to make a healthy lifestyle change. The first step was to determine the factors that influence college-aged students eating habits, and was presented with a review of relevant literature in several topics. We researched food literacy in young adults, the impact of fast food, social media's role in healthy eating habits, health behavior change in young adults, and the benefits of home cooking to obtain a general baseline of the knowledge of college-aged students. The initial research was utilized to write more effective blog posts that appropriately addressed our targeted demographic and to determine what platforms would be most appropriate to convey our information. These ideas were taken and then translated into a blog and Instagram account that contained healthy, copycat recipes of popular restaurant meals. We wrote 30 blog posts which were made up of 20 original recipes, 8 nutrition informational posts, and an introduction/conclusion. Finally, a focus group was hosted to ascertain the opinions of our peers, and to determine if they would be willing to make a lifestyle change in the form of cooking more frequently as opposed to eating out regularly. We provided them with a pre and post survey to gather their opinions before and after reviewing the findings of our research and project. We concluded that if given the information in an accessible way, college students are willing to eat in, not out.

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Date Created
2018-05

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Simulation of Atomic Structure around Defects in Anatase

Description

Titanium dioxide is an essential material under research for energy and environmental applications, chiefly through its photocatalytic properties. These properties allow it to be used for water-splitting, detoxification, and photovoltaics, in addition to its conventional uses in pigmentation and

Titanium dioxide is an essential material under research for energy and environmental applications, chiefly through its photocatalytic properties. These properties allow it to be used for water-splitting, detoxification, and photovoltaics, in addition to its conventional uses in pigmentation and sunscreen. Titanium dioxide exists in several polymorphic structures, of which the most common are rutile and anatase. We focused on anatase for the purposes of this research, due to its promising results for hydrolysis.

Anatase exists often in its reduced form (TiO2-x), enabling it to perform redox reactions through the absorption and release of oxygen into/from the crystal lattice. These processes result in structural changes, induced by defects in the material, which can theoretically be observed using advanced characterization methods. In situ electron microscopy is one of such methods, and can provide a window into these structural changes. However, in order to interpret the structural evolution caused by defects in materials, it is often necessary and pertinent to use atomistic simulations to compare the experimental images with models.

In this thesis project, we modeled the defect structures in anatase, around oxygen vacancies and at surfaces, using molecular dynamics, benchmarked with density functional theory. Using a “reactive” forcefield designed for the simulation of interactions between anatase and water that can model and treat bonding through the use of bond orders, different vacancy structures were analyzed and simulated. To compare these theoretical, generated models with experimental data, the “multislice approach” to TEM image simulation was used. We investigated a series of different vacancy configurations and surfaces and generated fingerprints for comparison with TEM experiments. This comparison demonstrated a proof of concept for a technique suggesting the possibility for the identification of oxygen vacancy structures directly from TEM images. This research aims to improve our atomic-level understanding of oxide materials, by providing a methodology for the analysis of vacancy formation from very subtle phenomena in TEM images.

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2019-05

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The Effects of Time Restricted Feeding on Mood

Description

Intermittent Fasting (IF) is defined as a cyclical eating pattern where an individual will fast for a specific increment of time, followed by caloric intake periods. Fasting is a crucial part of our ancestors’ adaptation to the stresses of famine

Intermittent Fasting (IF) is defined as a cyclical eating pattern where an individual will fast for a specific increment of time, followed by caloric intake periods. Fasting is a crucial part of our ancestors’ adaptation to the stresses of famine in order to maintain mental acuity and physical abilities during food deprivation. IF influences physiological changes such as: triggers protective metabolic pathways, increases metabolic flexibility and resilience, promotes DNA repair and autophagy, increases microbiome diversity and restores the natural cyclical fluctuations of the gut, increases BDNF expression in mood regulating neuronal circuits, and enhances synaptic plasticity of the brain. Research on the underlying causes of mood disorders has linked impairments in neuroplasticity and cellular resilience to this pathophysiology, which fasting could mitigate. Depression and anxiety are reported as the top impediments to academic performance. Thus, an easily implemented treatment such as intermittent fasting may be an option for combating impaired mental health in college students. This research study tested time restricted feeding (TRF) and its impact on mood states. It was hypothesized that: if college students follow a time restricted feeding pattern, then they will be less moody due to TRF’s effects on the metabolism, brain, and gut. The study consisted of 11 college students: 5 following a four-week adherence to TRF (8am-4pm eating window) and 6 in the control group. The POMS questionnaire was used to measure mood states. The participants height, weight, BMI, body fat %, and POMS scores were tested at the beginning and end of the 4 week intervention. The results were as follows: weight p=0.112 (statistical trend), BMI p=0.058 (nearly significant), body fat % p=0.114 (statistical trend), POMS p=0.014 (statistically significant). The data suggests that following a TRF eating pattern can decrease moodiness and improve mood states.

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Date Created
2019-05

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Content Analysis of Existing Nutrition Marketing Materials in Central Arizona Schools

Description

The objective of this study was to evaluate and compare the content of nutrition marketing materials within the cafeterias of schools in Central Arizona. By collecting photographs of marketing material from three elementary schools, one K-8 school, three middle schools

The objective of this study was to evaluate and compare the content of nutrition marketing materials within the cafeterias of schools in Central Arizona. By collecting photographs of marketing material from three elementary schools, one K-8 school, three middle schools and three high schools, 59 pieces of nutrition marketing were gathered. The schools chosen were a convenience sample and selected from schools that were already participating in ASU' s School Lunch Study. The photographs were sorted by grade level and then coded quantitatively and qualitatively for their purpose, visual components, strategies used and relevance. Results from this novel study provided insight into prevalence, size, textual content, educational content, strategies for fruit and vegetable marketing, messaging and overall design of existing nutrition marketing within the sample schools. This study found that the prevalence of nutrition marketing within all school cafeterias appeared to be low, particularly within elementary and middle schools. Diverse types of messaging were present among elementary, middle and high schools and a variety of appeals were utilized with little consistency. Many of the strategies used in the nutrition marketing appeared disconnected from the population it was intended to appeal to. Educational components were notably lacking within middle school cafeterias but were often effectively integrated into high school nutrition marketing. The results are unique to this population, and further research is required to evaluate the content of existing nutrition material on a larger scale, so efforts can be made to improve the persuasiveness of nutrition marketing in promoting fruit and vegetable consumption.

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Date Created
2018-12

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Examination of an Organometallic Complex on Insulin Resistance in Periadolescent Male Rats Following a 10-week High Fat Diet

Description

With the rising prevalence of obesity and diabetes, novel treatments to help mitigate or prevent symptoms of these conditions are warranted. Prior studies have shown that fossilized plant materials found in soil lowers blood sugar in a mouse model of

With the rising prevalence of obesity and diabetes, novel treatments to help mitigate or prevent symptoms of these conditions are warranted. Prior studies have shown that fossilized plant materials found in soil lowers blood sugar in a mouse model of diabetes. The goal of this study is to determine whether a similar organometallic complex (OMC) could prevent insulin resistance in the skeletal muscle brought on by chronic high fat intake by examining the protein expression of key enzymes in the insulin signaling pathway and examining glucoregulatory measures. Six-week-old periadolescent male Sprague-Dawley rats (n=42) were randomly chosen to be fed either a high fat diet (HFD) (20% protein, 20% carbohydrates [6.8% sucrose], 60% fat) or a standard chow diet (18.9% protein, 57.33% carbohydrates, 5% fat) for 10 weeks. Rats from each diet group were then randomly assigned to one of three doses of OMC (0, 0.6, 3.0 mg/mL), which was added to their drinking water and fasting blood glucose was measured at baseline and again at 10 weeks. After 10 weeks, rats were euthanized, and soleus muscle samples were isolated, snap-frozen, and stored at -80°C until analyses. Fasting plasma glucose was measured using a commercially available glucose oxidase kit. Following 6 and 10 weeks, HFD rats developed significant hyperglycemia (p<0.001 and p=0.025) compared to chow controls which was prevented by high dose OMC (p=0.021). After 10 weeks, there were significant differences in fasting serum insulin between diets (p=0.009) where levels were higher in HFD rats. No significant difference was seen in p-PI3K expression between groups. These results suggest that OMC could prevent insulin resistance by reducing hyperglycemia. Further studies are needed to characterize the effects of diet and OMC on the insulin signaling pathway in skeletal muscle, the main site of postprandial glucose disposal. This study was supported by a grant from Isagenix International LLC as well as funds from Barrett, the Honors College at Arizona State University, Tempe Campus.

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2018-12

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2D or Not To Be: The Story and Science of Graphene

Description

The story of graphene truly began in what was simply a stub in the journal Physical Review not two years after the end of World War II. In 1947, McGill University physicist P.R. Wallace authored “The Band Theory of Graphite”

The story of graphene truly began in what was simply a stub in the journal Physical Review not two years after the end of World War II. In 1947, McGill University physicist P.R. Wallace authored “The Band Theory of Graphite” and attempted to develop a foundation on which the structure-property relationship of graphite could be explored; he calculates the number of free electrons and conductivity of what he describes as “a single hexagonal layer” and “suppos[es] that conduction takes place only in layers” in bulk graphite to predict wave functions, energies at specific atomic sites in the hexagonal lattice, and energy contours using a tight binding approximation for a hypothesized version of what we now call ‘armchair-style’ graphene. While Wallace was the first to explore the band structure and Brillouin Zones of single-layer graphite, the concept of two-dimensional materials was not new. In fact, for years, it was dismissed as a thermodynamic impossibility.

Everything seemed poised against any proposed physical and experimental stability of a structure like graphene. “Thermodynamically impossible”– a not uncommon shutdown to proposed novel physical or chemical concepts– was once used to describe the entire field of proposed two-dimensional crystals functioning separately from a three-dimensional base or crystalline structure. Rudolf Peierls and Lev Davoidovich Landau, both very accomplished physicists respectively known for the Manhattan Project and for developing a mathematical theory of helium superfluidity, rejected the possibility of isolated monolayer to few-layered crystal lattices. Their reasoning was that diverging thermodynamic-based crystal lattice fluctuations would render the material unstable regardless of controlled temperature. This logic is flawed, but not necessarily inaccurate– diamond, for instance, is thermodynamically metastable at room temperature and pressure in that there exists a slow (i.e. slow on the scale of millions of years) but continuous transformation to graphite. However, this logic was used to support an explanation of thermodynamic impossibility that was provided for graphene’s lack of isolation as late as 1979 by Cornell solid-state physicist Nathaniel David Mermin. These physicists’ claims had clear and consistent grounding in experimental data: as thin films become thinner, there exists a trend of a decreasing melting temperature and increasing instability that renders the films into islands at somewhere around ten to twenty atomic layers. This is driven by the thermodynamically-favorable minimization of surface energy.

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2018-05

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Incorporating Nutritional Support as Complementary Therapy for Cancer Patients Undergoing Chemotherapy Treatment

Description

Nutritional support offered before and during chemotherapy treatment is proven to improve the outcomes of treatment (Bernhardson, 2016). This project seeks to examine current forms of nutritional support offered to patients, as well as the models of care and support

Nutritional support offered before and during chemotherapy treatment is proven to improve the outcomes of treatment (Bernhardson, 2016). This project seeks to examine current forms of nutritional support offered to patients, as well as the models of care and support teams in cancer treatment centers. The basis for this project incorporated personal experiences at M.D. Anderson Cancer Center in Gilbert, Arizona as well as research into the work of clinical oncology dietitians. An intense interest in food videos and blogs also informed this project, and was incorporated in the hope of providing chemotherapy patients a platform to discover recipes specific to their unique situation. The combination of this research was utilized to create several videos which demonstrated specific recipes beneficial for patients as well as creating a platform for this particular population. While nutritional support can take multiple forms, the focus of nutritional support surrounds symptom management. The common side effects of chemotherapy such as nausea, mucositis (mouth sores), and extreme weight loss were taken into account. Recipes were formulated to directly address these conditions and each recipe was broken down into the benefits of both macronutrients and micronutrients. In addition to formulating specific recipes and videos, barriers to proper nutritional support were examined and explained. These barriers include understaffing of clinical dietitians at cancer treatment centers, a patient's lack of transportation to and from treatments, as well as an overwhelming viewpoint that nutritional support is only required for extreme cases of malnutrition. Combatting these barriers and offering more forms of nutritional support will help to increase a patient's positive response to treatment, manage their symptoms, and improve their overall quality of life.

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Date Created
2018-12

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Two Degrees Celsius: Reducing the Negative Ecological Impact and Creating Sustainability in the Beef Industry

Description

In this moment, as I find myself on the brink of transition from my undergraduate studies into my postgraduate endeavors, I find my conscious drift back and forth between reflection on my experience to date, and contemplation of what awaits.

In this moment, as I find myself on the brink of transition from my undergraduate studies into my postgraduate endeavors, I find my conscious drift back and forth between reflection on my experience to date, and contemplation of what awaits. As I reach this milestone, I am challenged with the task of creating a thesis that not only projects what I have learned and how I have grown in my time at Barrett, the Honors College, but how I will continue to grow and impact the world into which I set out. This growth, subtle yet constant permeates my collegiate experience. I have grown in knowledge, experience, and maturity. I am more self-aware yet working to become less self-conscious, and more selfless. I have made lasting memories I wish I could relive and reckless mistakes I wish I could forget, but both wishes are unavailable, and would be unproductive if granted. I have only grown by being open to new experiences that I may one day cherish and avoiding the pitfalls that have brought forth instances of destruction and despair. I hope to represent this growth in this thesis so that it may serve as a launching pad for me and for those who read it, so that together we can begin to solve the problem I address, a problem that has grown but which we must not allow to grown out of control.

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Date Created
2019-05