Matching Items (765)
Filtering by
- All Subjects: engineering
- Creators: Arizona State University
Description
Urease, an amidohydrolase, is an essential ingredient in the emerging engineering technique of biocementation. When free urease enzyme is used this carbonate precipitation process is often referred to as enzyme induced carbonate precipitation (EICP). To date, most engineering applications of EICP have used commercially available powdered urease. However, the high cost of commercially available urease is a major barrier to adoption of engineering applications of EICP in practice. The objective of this dissertation was to develop a simple and inexpensive enzyme production technique using agricultural resources. The specific objectives of this dissertation were (i) to develop a simple extraction process to obtain urease from common agricultural resources and identify a preferred agricultural resource for further study, (ii) to reduce the cost of enzyme production by eliminating the use of a buffer, centrifugation, and dehusking of the beans during the extraction process, (iii) investigate the stability of the extracted enzyme both in solution and after reduction to a powder by lyophilization (freeze-drying), and (iv) to study the kinetics of the extracted enzyme.
The results presented in this dissertation confirmed that inexpensive crude extracts of urease from agricultural products, including jack beans, soybeans, and watermelon seeds, are effective at catalyzing urea hydrolysis for carbonate precipitation. Based upon unit yield, jack beans were identified as the preferred agricultural resource for urease extraction. Results also showed that the jack bean extract retained its activity even after replacing the buffer with tap water and eliminating acetone fractionation, centrifugation, and dehusking. It was also found that the lyophilized crude extract maintained its activity during storage for at least one year and more effectively than either the crude extract solution or rehydrated commercial urease. The kinetics of the extracted enzyme was studied to gain greater insight into the optimum concentration of urea in engineering applications of EICP. Results showed higher values for the half-saturation coefficient of the crude extract compared to the commercial enzymes.
The results presented in this dissertation demonstrate the potential for a significant reduction in the cost of applying EICP in engineering practice by mass production of urease enzyme via a simple extraction process.
ContributorsJavadi, Neda (Author) / Kavazanjian, Edward (Thesis advisor) / Khodadadi Tirkolaei, Hamed (Committee member) / Hamadan, Naser (Committee member) / Delgado, Anca (Committee member) / Arizona State University (Publisher)
Created2021
Description
The world faces significant environmental and social challenges due to high economic development, population growth, industrialization, rapid urbanization, and unsustainable consumption. Global communities are taking the necessary measures to confront these international challenges and applying sustainable development principles across all sectors. Construction is a critical driving instrument of economic activity, and to achieve sustainable development, it is vital to transform conventional construction into a more sustainable model. The research investigated sustainable construction perceptions in Kuwait, a rapidly growing country with a high volume of construction activities. Kuwait has ambitious plans to transition into a more sustainable economic development model, and the construction industry needs to align with these plans. This research aims to identify the characteristics of sustainable construction applications in the Kuwaiti construction market, such as awareness, current perceptions, drivers and barriers, and the construction regulations' impact. The research utilized a qualitative approach to answer research questions and deliver research objectives by conducting eleven Semi-structured interviews with experienced professionals in the Kuwaiti construction market to collect rich data that reflects insights and understandings of the Kuwaiti construction industry. The Thematic analysis of the data resulted in six themes and one sub-theme that presented reflections, insights, and perspectives on sustainable construction perceptions in the Kuwaiti construction market. The research findings reflected poor sustainable construction awareness and poor environmental and social application in the construction industry, the determinant role of construction regulations in promoting sustainable construction. and barriers and drivers to sustainable construction applications. The research concluded with answers to research questions, delivery of research objectives, and an explanation of sustainable construction perceptions in the Kuwaiti construction market.
Contributorsalsalem, mohammad salem (Author) / Duran, Melanie (Thesis advisor) / Chong, Oswald (Committee member) / Sullivan, Kenneth (Committee member) / Grau, David (Committee member) / Arizona State University (Publisher)
Created2023
Description
Delamination of solar module interfaces often occurs in field-tested solar modules after decades of service due to environmental stressors such as humidity. In the presence of water, the interfaces between the encapsulant and the cell, glass, and backsheet all experience losses of adhesion, exposing the module to accelerated degradation. Understanding the relation between interfacial adhesion and water content inside photovoltaic modules can help mitigate detrimental power losses. Water content measurements via water reflectometry detection combined with 180° peel tests were used to study adhesion of module materials exposed to damp heat and dry heat conditions. The effect of temperature, cumulative water dose, and water content on interfacial adhesion between ethylene vinyl acetate and (1) glass, (2) front of the cell, and (3) backsheet was studied. Temperature and time decreased adhesion at all these interfaces. Water content in the sample during the measurement showed significant decreases in adhesion for the Backsheet/Ethylene vinyl acetate interface. Water dose showed little effect for the Glass/ Ethylene vinyl acetate and Backsheet/ Ethylene vinyl acetate interfaces, but there was significant adhesion loss with water dose at the front cell busbar/encapsulant interface. Initial tensile test results to monitor the effects of the mechanical properties ethylene vinyl acetate and backsheet showed water content increasing the strength of ethylene vinyl acetate during plastic deformation but no change in the strength of the backsheet properties. This mechanical property change is likely inducing variation along the peel interface to possibly convolute the adhesion measurements conducted or to explain the variation seen for the water saturated and dried peel test sample types.
ContributorsTheut, Nicholas (Author) / Bertoni, Mariana (Thesis advisor) / Holman, Zachary (Committee member) / Chan, Candace (Committee member) / Arizona State University (Publisher)
Created2020
Description
The complex network of the immune system defends the human body against infection, providing protection from pathogens. This work aims to improve preparation and structural knowledge of two proteins on opposite sides of the immune system spectrum. The first protein, secreted autotransporter toxin (Sat) is a class I serine protease autotransporter of Enterobacteriaceae (SPATE) that has cytotoxic and immunomodulatory effects on the host. Previous studies on Sat show its ability to aid in bacterial colonization and evasion of the immune system. This work improves the stability of Sat by making mutations to the active serine protease motif (GDSGS) while inhibiting remaining activity with reversible and irreversible serine protease inhibitors. Characterization of Sat by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and size-exclusion chromatography led to the first structural studies of Sat by x-ray crystallography and cryo-EM. Human leukocyte antigen class I proteins play an important role in the adaptive immune system by presenting endogenous viral peptides at the cell surface for CD8+ T cell recognition. In vitro production of HLA-I proteins is a difficult task without endoplasmic reticulum chaperones as present in vivo. Disulfide bond formation, folded light chain and a peptide bound are all key to refolding the HLA-I heavy chain for complex formation. The work presented in this dissertation represents systematic studies aimed at improving the production of HLA-I proteins in vitro in bacterial expression systems. Optimization of every step of the preparation was investigated providing higher expression yields, quality of inclusion bodies, and refolding improvements. With further improvements in the future, this work forms the basis for a more efficient small and large-scale production of HLA-I molecules for functional and structural studies.
ContributorsKiefer, Dalton (Author) / Anderson, Karen (Thesis advisor) / Fromme, Petra (Thesis advisor) / Chiu, Po-Lin (Committee member) / Mazor, Yuval (Committee member) / Arizona State University (Publisher)
Created2024
Description
The thylakoid membranes of oxygenic photosynthetic organisms contain four large membrane complexes vital for photosynthesis: photosystem II and photosystem I (PSII and PSI, respectively), the cytochrome b6f complex and ATP synthase. Two of these complexes, PSII and PSI, utilize solar energy to carry out the primary reaction of photosynthesis, light induced charge separation. In vivo, both photosystems associate with multiple antennae to increase their light absorption cross section. The antennae, Iron Stress Induced A (IsiA), is expressed in cyanobacteria as part of general stress response and forms a ring system around PSI. IsiA is a member of a large and relatively unexplored antennae family prevalent in cyanobacteria. The structure of the PSI-IsiA super-complex from the cyanobacteria Synechocystis sp. PCC 6803 was resolved to high resolution, revealing how IsiA interacts with PSI as well as the chlorophyll organization within this antennae system. Despite these structural insights, the basis for the binding between 18 IsiA subits and PSI is not fully resolved. Several IsiA mutants were constructed using insights from the atomic structure of PSI-IsiA, revealing the role of the C-terminus of IsiA in its interaction with PSI.
ContributorsLi, Jin (Author) / Mazor, Yuval (Thesis advisor) / Chiu, Po-Lin (Committee member) / Mills, Jeremy (Committee member) / Arizona State University (Publisher)
Created2024