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3D Bioprinting of Hydrogel Microparticles Through Conversion of Dual-Extrusion Bioprinters
Get PDFOver the past decade, additive manufacturing has resulted in significant advances towards fabricating anatomic-size, patient-specific scaffolds for tissue models and regenerative medicine. This can be attributed to the development of advanced bioinks capable of precise deposition of cells and biomaterials. The combination of additive manufacturing with advanced bioinks is enabling researchers to fabricate intricate tissue scaffolds that recreate the complex spatial distributions of cells and bioactive cues found in the human body. However, the expansion of this promising technique has been hampered by the high cost of commercially available bioprinters and proprietary software. In contrast, conventional 3D printing has become increasingly popular with home hobbyists and caused an explosion of both low-cost thermoplastic 3D printers and open-source software to control the printer. In this thesis, we bring these benefits into the field of bioprinting by converting widely available and cost-effective 3D printers into fully functional, open source, and customizable multi-head bioprinters. We demonstrate the practicality of this approach by designing bioprinters customized with multiple extruders, automatic bed leveling, and temperature controls for approximately $400. Type-1 diabetes is a chronic condition in which the pancreas produces little or no insulin, caused by the destruction of the insulin-producing beta cells of the pancreas. Traditional strategies for treating type-1 diabetes, involving beta-cell transplantation or delivery, have shown mixed results due to loss of cell viability and decreased efficacy. Three-dimensional (3D) bioprinting of microgel bioinks has shown potential to circumvent some of these challenges and meet the needs for tissue engineering and cell delivery. The converted bioprinters in this thesis make 3D bioprinting a scalable solution to treating chronic diseases like T1D
The Effect of Learning Assistants on Undergraduate Sense of Belonging in an Anatomy and Physiology Lab Course
Get PDFThe purpose of this study was to gain an understanding of whether or not Learning Assistants created sense of belonging among students enrolled in an Anatomy and Physiology I Lab course during the Fall 2022 semester. A one-group, pretest-posttest quantitative design was used to collect survey data using Qualtrics, and several analyses were performed including paired sample t-tests, Pearson correlations, repeated measures ANCOVA and ANOVA, along with one-way ANCOVA using SPSS. Students completed the Departmental Sense of Belonging and Involvement Questionnaire before working with Learning Assistants, and then throughout the semester, they worked with Learning assistants both in and out of the classroom to strengthen their understanding of the material. At the end of the semester, students were asked to complete the same survey again. When post-test survey scores were compared to pre-test scores, statistically significant changes in sense of belonging occurred in all three sense of belonging survey subscales (valued competence, social acceptance and involvement). This analysis was confirmed by several statistical tests. Additionally, when data from three groups of students (new students with no prior experience with LAs, returning students with no prior experience with LAs, and returning students with prior experience with LAs) was analyzed, all three significantly changed in sense of belonging from pre-test to post-test, with the returning students with prior experience with LAs displaying the largest change in two of the sense of belonging subscales (valued competence and social acceptance), and the smallest change in the third subscale (involvement). The means of all students decreased for the involvement subscale, which prompted the involvement survey items to be rewritten for my artifact. These new items will be used in a future implementation of the survey
Minimum-Cost Coordinated Routing of Two UAVs Under Communication Constraints
No full textThis thesis addresses an optimization problem to minimize the time for two Unmanned Aerial Vehicles (UAVs) to cover a set of targets in a coordinated manner while maintaining within a specified proximity of one another at all times. The results of this study provide a framework for UAV mission planning or other applications where multiple UAVs are required to cover a given set of targets while adhering to proximity constraints for maintaining communication. We specifically consider a routing problem where an even number of targets are to be covered and each UAV covers the same number of targets. An integer linear programming model (ILP) is formulated to determine the optimal routes for both UAVs. This ILP is computationally expensive to solve which makes it impractical to obtain solutions as the problem size scales up. Therefore, a local search heuristic was formulated to approximate the optimal solutions for the proposed problem within a shorter time frame. The quality of the heuristic was measured by comparing its solutions against those from a linear programming model (LP) and from another ILP, both of which serve as lower-bounds to the optimal solution. The heuristic was implemented in Python, which was also used to implement the Gurobi optimizer for solving the LP and ILP. Our findings indicate that the heuristic consistently delivered higher-quality solutions when smaller UAV proximity requirements were imposed. Furthermore, it was observed that the lower-bound ILP provided tighter benchmarks for approximating the optimal solution compared to the LP, albeit at a higher computational cost as the problem size scaled up
Introduction of the Concept of a Time-Based Threshold of Galvanized Steel in Simulated Concrete Pore Solution Based on Short- and Long-Term Immersion
No full textThe most used type of construction material worldwide is reinforced concrete. Concrete can survive the effects of time and stress in harsh conditions and protect the steel it is encasing, especially against alkali. Nevertheless, it becomes weak when exposed to marine environments, with carbonation and chloride ion assault being the main causes of breakdown. One of the main problems with steel rebars is that they rust because of an electrochemical process in which iron dissolves anodically and oxygen reduces cathodically. The pore solution of the concrete acts as the electrolyte. Aggressive substances that penetrate the concrete up to the rebar, such as carbonate and chloride ions, cause this phenomenon to emerge. When you galvanize instead of painting or coating something, a metallic link is formed between the zinc and the steel substrate of the rebar. The coating���s integrity stays mostly the same even if it gets damaged during shipping, storage, or use. The steel surface is protected on two different levels by this coating. On its surface, zinc develops a dense oxide layer that provides barrier defense. In the event of damage, zinc corrodes sacrificially and offers cathodic protection to the steel substrate. This work characterizes the Zn/steel interface in concrete pore solution when used as reinforced rebar in concrete. The study included inter-facial experimental chemical studies to introduce the concept of the second threshold of rebars. We can use the phrase "chloride threshold" to describe the level of harmful species that can get into rebars and attack them, especially the Zn coating on these rebars. Another threshold can be defined as the attack on the steel substrate itself after the coating layer has deteriorated. The threshold word alludes to the content (mostly chloride) at which rebar corrosion in an alkaline environment reaches a critical level. This work provides a threshold concept for two different galvanized steel rebars (hot dipping and continuous process), such as the classical threshold concept for bare steel materials used in reinforced concrete structures. To estimate the threshold, an indentation is made on the samples to accelerate the corrosion and compare them with the non-indented samples
Identification of Swimming Strokes Using Smart Devices
Get PDFEvaluations of swimming education programs by the Red Cross produced startling results: swimming education programs do not substantially reduce drowning deaths. Exploring solutions to this issue is paramount, as over 300,000 drowning deaths occur worldwide. One possible weakness of swimming education programs is their focus on competitive swimming strokes (breaststroke, backstroke, freestyle, and butterfly), rather than treading water and sidestroke, which are instrumental in surviving tough water situations. However, focus on competitive swimming strokes is not limited to swimming education programs. The rise of smartwatches has led to fitness tracking products for a variety of physical activities, including swimming. Swimming trackers on the market today such as the Apple Watch, can only identify competitive swimming strokes. Our identification system seeks to identify all competitive swimming strokes as well as the sidestroke and treading water to help address the limitations of current systems
