Matching Items (298)
Description
The gold standard of treatment for large bone defects remains autograft bone, which suffers from limited availability and donor-site morbidity. As an alternative, bone tissue engineering seeks to use a combination of cells, biomolecules, and biomaterials to regenerate functional bone tissue. Hydroxyapatite is a key component of bone tissue and is particularly important for its function. Here, we developed an approach to mineralize electrospun fibers to mimic native bone mineralization and serve as a scaffold for bone repair. Two types of electrospun fiber systems were investigated: polycaprolactone (PCL) and norbornene-functionalized cellulose acetate (nor-CA). PCL fiber surfaces were activated with sodium hydroxide and calcium phosphate. Next, the fibrous scaffolds were incubated in simulated body fluid (SBF) for seven days. Three types of SBF were chosen for incubation: conventional (C-SBF), revised (R-SBF), and 4x revised (4x R-SBF). Mineralization was assessed using energy-dispersive X-ray spectroscopy, Alizarin Red S staining, and scanning electron microscopy. Calcium phosphate and sodium chloride-based mineralization were observed for all SBF formulations for PCL. 4x R-SBF resulted in a calcium-to-phosphorus molar ratio most like native hydroxyapatite. R-SBF also had a calcium-to-phosphorus ratio similar to that of hydroxyapatite. R-SBF and 4x R-SBF resulted in lower values of sodium deposition on PCL when compared to C-SBF and had distinct regions of calcium-phosphate and sodium-chloride mineralization. Nor-CA was synthesized using a Boc2O esterification reaction between 5-norbornene-2-carboxylic acid and cellulose acetate, and analysis revealed the norbornene functionalization to be 60.02%. A fluorescent dye, 7-mercapto-4-methylcoumarin, was also successfully bound to the surface of nor-CA fibers using a UV-mediated thiol-ene reaction. The selectivity of the reaction between samples exposed to UV and kept in the dark requires improvement in future work.
ContributorsKupfer, Joshua (Author) / Holloway, Julianne (Thesis director) / Schwarz, Grace (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
The process of wet granulation is a widely used process in which fine particles are agglomerated into a larger particle using a liquid binder. Understanding this process can help to standardize powder properties and improve transport efficiency. The practice of granulation is really influenced by various particle properties, powder properties, and specifications of equipment design. Determining how to predict the formation and breakage of granules in a consistent and predictable manner are important for its industrial applications and future research studies.
This study first looked at how penetration time of a drop into a powder bed depends on the impact velocity of the drop for several different viscosity liquid binders. A high-speed camera captured the impact time at several different height values of single-drop granulation. For lower viscosity liquids, penetration time decreases with increasing impact velocity. However, the trend reverses when using very high viscosity liquid binders. Another aim of this study was to look at granule breakage as a function of rotational speed in a granulator with several liquid binders with varying properties. 20 single-drop granules were made separately and placed in a high-shear granulator, where after 1 minute of mixing the final breakage fraction was recorded. Breakage rate generally increases with higher rotational speeds, however several factors such as viscosity, surface tension, and granule saturation also affect this breakage.
ContributorsMomeyer, Jason (Author) / Emady, Heather (Thesis director) / Kumar, Diana (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
In this work, a series of polydimethylsiloxane (PDMS) composite membranes were fabricated by using vinyl-terminated PDMS with polyhydomethylsiloxane (PHMS) as a cross-linker, with a hydrophobic DeltaMem PERVAPTM 4155-80 support layer, through drawdown casting with a doctor blade. The original goal of the work was to control cross-link density of the membranes by varying the ratio of cross-linker to PDMS, and examining the effect of cross-link density on performance of the membranes under pervaporation. The goal of the work shifted to optimizing the fabrication procedure to produce usable membranes after initial attempts at fabrication were unsuccessful. It was found that viscosity of the polymer solution, heating time, degassing time, and the application of the support layer played key roles in determining the success of the membrane fabrication. No usable membranes were fabricated and pervaporation data was not collected, but many insights were gained into the process of membrane fabrication and the different methods that can be used to fabricate PDMS membranes. This work demonstrated the need for further study into alternative methods for membrane fabrication, and key avenues to explore to optimize the process.
ContributorsAskew, Bryce (Author) / Green, Matthew (Thesis director) / Telenar, Taysha (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
In order to achieve net zero emissions and slow global warming, a shift to renewable energy must be made. Photovoltaics projects on the utility-scale have grown to meet this need, and while they offer a clean source of energy, utility-scale solar also has its own unique set of challenges. The scale of projects and accompanying land disturbance from utility-scale solar has negative effects on the agricultural industry or biodiversity, depending on where the project is built. Agrivoltaics, the combination of agriculture and photovoltaics, offers a solution to these issues by making the land multi-functional or reducing the impact land-clearing for photovoltaics has. Agrivoltaics can be split into three types, crop-based, where crops are grown underneath panels, pollinator-friendly, where habitat and biodiversity is restored within the solar project, or grazing-based, where livestock graze under the solar infrastructure. The feasibility of each type was explored in this study, as well as the best-use cases for each. A series of seven in-depth, semi-structured interviews were conducted with subject matter experts on each type of agrivoltaics and utility-scale solar, which determined that pollinator-friendly and grazing-based agrivoltaics are the most feasible on a utility-scale solar site. Experts agreed there is no one solution for agrivoltaics, and that the best option to improve a solar project will be dependent on location and previous land-use. Currently, the best-use case for crop-based agrivoltaics was determined to be on a small scale, with crops that benefit from the shade, and in arid and semi-arid regions. Pollinator-friendly agrivoltaics finds its best-use on any solar site where native plants can grow. Pollinator-friendly can be implemented with varying degrees of execution, from full habitat restoration to small sections of native plants around the solar array. Finally, grazing-based agrivoltaics is best implemented when the cost to do traditional vegetation management is comparable and the location is suitable for livestock. In the future, cattle grazing-based agrivoltaics could be implemented on large cattle ranches. Overall, research suggests that agrivoltaics is a good solution for reducing the negative effects of utility-scale solar.
ContributorsReed, Grace (Author) / Carr Kelman, Candice (Thesis director) / Kelman, Jonathan (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
The Experimental Data Processing (EDP) software is a C++ GUI-based application to streamline the process of creating a model for structural systems based on experimental data. EDP is designed to process raw data, filter the data for noise and outliers, create a fitted model to describe that data, complete a probabilistic analysis to describe the variation between replicates of the experimental process, and analyze reliability of a structural system based on that model. In order to help design the EDP software to perform the full analysis, the probabilistic and regression modeling aspects of this analysis have been explored. The focus has been on creating and analyzing probabilistic models for the data, adding multivariate and nonparametric fits to raw data, and developing computational techniques that allow for these methods to be properly implemented within EDP. For creating a probabilistic model of replicate data, the normal, lognormal, gamma, Weibull, and generalized exponential distributions have been explored. Goodness-of-fit tests, including the chi-squared, Anderson-Darling, and Kolmogorov-Smirnoff tests, have been used in order to analyze the effectiveness of any of these probabilistic models in describing the variation of parameters between replicates of an experimental test. An example using Young's modulus data for a Kevlar-49 Swath stress-strain test was used in order to demonstrate how this analysis is performed within EDP. In order to implement the distributions, numerical solutions for the gamma, beta, and hypergeometric functions were implemented, along with an arbitrary precision library to store numbers that exceed the maximum size of double-precision floating point digits. To create a multivariate fit, the multilinear solution was created as the simplest solution to the multivariate regression problem. This solution was then extended to solve nonlinear problems that can be linearized into multiple separable terms. These problems were solved analytically with the closed-form solution for the multilinear regression, and then by using a QR decomposition to solve numerically while avoiding numerical instabilities associated with matrix inversion. For nonparametric regression, or smoothing, the loess method was developed as a robust technique for filtering noise while maintaining the general structure of the data points. The loess solution was created by addressing concerns associated with simpler smoothing methods, including the running mean, running line, and kernel smoothing techniques, and combining the ability of each of these methods to resolve those issues. The loess smoothing method involves weighting each point in a partition of the data set, and then adding either a line or a polynomial fit within that partition. Both linear and quadratic methods were applied to a carbon fiber compression test, showing that the quadratic model was more accurate but the linear model had a shape that was more effective for analyzing the experimental data. Finally, the EDP program itself was explored to consider its current functionalities for processing data, as described by shear tests on carbon fiber data, and the future functionalities to be developed. The probabilistic and raw data processing capabilities were demonstrated within EDP, and the multivariate and loess analysis was demonstrated using R. As the functionality and relevant considerations for these methods have been developed, the immediate goal is to finish implementing and integrating these additional features into a version of EDP that performs a full streamlined structural analysis on experimental data.
ContributorsMarkov, Elan Richard (Author) / Rajan, Subramaniam (Thesis director) / Khaled, Bilal (Committee member) / Chemical Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Ira A. Fulton School of Engineering (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The yeast project studies the growth of yeast Saccharomyces Cerevisiae (S. Cerevisiae) in high and low sulfate environments and analyzes the potential for genetically mutated plasmids to facilitate sulfate uptake in gene deficient yeast medias. The goal of the project was to transform the Sul1 and Sul2 transporters into the nutrient deficient yeast strain BY4743 and observe growth in conditions that would otherwise prohibit growth in order to create a model that can be used to study the effect of sulfate concentration on the transporters. The experimental results showed that expressing the sulfate transporters in the BY4743 strain provided the potential for the yeast to grow in nutrient-poor media. The growth potential model allows for further analysis on the sulfate transporters and will be used for research projects going forward.
ContributorsDickieson, Maxim Park (Author) / Nannenga, Brent (Thesis director) / Pena, Fred (Committee member) / Ira A. Fulton School of Engineering (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Selective separation of environmentally relevant oxyanions is critical for water treatment and resource recovery. In this study, density functional theory (DFT) was used to evaluate the adsorption behavior of vanadate (H₂VO₄⁻), chromate (HCrO₄⁻), silicate (H₄SiO₄), and perchlorate (ClO₄⁻) on porphyrin derivatives. Modifications included functionalization, metalation, and a combination of both. The hypothesis posited that combining functionalization and metalation would enhance selectivity for toxic oxyanions (vanadate and chromate) over structurally similar, benign species. Binding energies revealed that functionalization alone did not improve selectivity, with silicate showing the strongest binding with an average of –0.780 eV due to extensive hydrogen bonding. Metalation significantly increased binding strength. V porphyrins in the 3+ state exhibited the following lowest binding energy values: –2.873 eV, –2.621 eV for chromate and vanadate, respectively. Selectivity, defined as a minimum of 0.1 eV difference in binding energy between target and competing adsorbates, was achieved in metallated systems, particularly for V 3+ porphyrins with chromate with a binding energy of 0.370 eV over silicate. The combination of functionalization and metalation offered minimal additional improvement over metallation.
These results highlight metalation, especially with high-valent vanadium and iron, as the dominant factor in enhancing selective oxyanion adsorption, whereas functionalization contributes little additional benefit. The findings support the rational design of metalloporphyrins for targeted contaminant removal applications.
ContributorsPark, Hannah (Author) / Muhich, Christopher (Thesis director) / D'arcy, Richard (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
The misuse of personal pronouns when referring to individuals has increased immensely, and as a result, misgendering has become commonplace. This creates uncomfortable social situations and can exacerbate already stressful situations such as meeting new people or traveling to new places. Taking information from my own experiences with these issues when abroad and combining with personal experiences from other individuals, the added stress due to misgendering can be addressed effectively. Data collection occurred in order to address awareness of situations, inclusivity of locations, and language when referring to people. A survey was used as a medium to gather the data. Questions asked related to the relationship between inclusivity and misgendering as well as unfamiliarity and travel. Information gathered in this study yielded two major takeaways: misgendering occurs similarly between individuals familiar and unfamiliar with the knowledge of gender-inclusivity and misgendering, and that further awareness of misgendering should be brought to the public. Further suggestions were created to better address the conclusions. The simplest action is to ask for an individual’s personal pronouns or gender identity when meeting them for the first time. This eliminates the chance of misgendering by unfamiliarity by making the other party familiar with the gender identity. The second suggestion is to use more words that do not address one gender in particular.
ContributorsGlaser, Sam (Author) / Briggs, Georgette (Thesis director) / Thomas, Kathy (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05