Browsing by Author "Wang, Yifei"
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Item Aquifer Experiments for Characterizing NAPL Sources and Dissolved Plumes following Releases of Ethanol-Blended Fuels(2020-05) Wang, Yifei; Rixey, William G.; Alvarez, Pedro J. J.; Louie, Stacey M.; Shaffer, Devin L.; Vipulanandan, CumaraswamyThis research investigated impacts of releases to the subsurface of ethanol-blended fuels. The overall purpose was to study the evolution of a dissolved plume and non-aqueous phase liquid (NAPL) that is formed/displaced for different fuel ethanol contents in order to develop an understanding of how ethanol fuel contents affect the release, transport, and transformation of ethanol as well as hydrocarbon impacts on water quality. In the first part of the research, low (E25) and high (E85) ethanol fuel blends were released in the unsaturated zone of a pilot-scale aquifer. Pore water concentrations were monitored in the unsaturated zone, in the saturated zone, and in the effluent following the releases. The second part of the research involved smaller-scale studies of ethanol fuel releases in 2D physical model continuous flow cell experiments to better quantify and understand ethanol recovery and the extent of transformation from the large-scale releases of these fuels. These experiments allowed for the visualization of the transport of ethanol in the pore water and the formation of NAPL from the fuel releases. Evaluation of the impacts of these ethanol fuel releases has shown: 1) retention of ethanol in the unsaturated zone for releases containing high ethanol content due to buoyancy, 2) for low ethanol content fuels a fraction of the ethanol was released slowly, controlled by diffusion from the NAPL source, and 3) more rapid source depletion (for high ethanol content) of the more soluble hydrocarbon components in the fuel due to lower NAPL saturation. This research is useful for assessing the extent and persistence of groundwater impacts for realistic spills or leaks of fuels containing ethanol. The results of this research not only apply to ethanol but are also relevant to other alcohols being considered as alternative fuels.Item DESIGN AND DEVELOPMENT OF PATCHY LIPOSOMES AS POTENTIAL DELIVERY CARRIERS WITH ENHANCED FUSOGENICITY OR BINDING ABILITY(2023-05-11) Wang, Yifei; Majd, Sheereen; Abidian, Mohammad Reza; Wu, Tianfu; Chow, Diana Shu-Lian; Du, GuangweiNanoliposomes are one of the most commonly used delivery nanocarriers due to their biocompatibility, biodegradability, and low toxicity. To achieve high levels of cellular uptake, liposomes often require large doses of fusion-promoting molecules or targeting ligands that can lead to undesired side effects, including toxicity and immunogenicity. To address this challenge, this project aims to utilize the biological process of membrane phase-separation to design and develop liposomes that can offer highly efficient cellular internalization with minimal toxicity. First part of this dissertation combines experimental and computational tools to investigate the phase behavior of multi-component lipid membranes. The experimental studies focused on studying phase-separation on micron-sized liposomes of various compositions using fluorescence microscopy. In collaboration with mathematicians, two continuum phase-field models were then developed to simulate the phase-separation examined in experiments. Great agreement between experiments and simulations validated the computational models and demonstrated their potential use for the design of phase-separating and patchy liposomes. Second part of this dissertation explores the use of phase-separation to create highly fusogenic liposomal nanocarriers with minimal toxicity. The impact of charged lipids on membrane’s phase behavior was first investigated in multi-component micron-sized liposomes. The findings of this work were then applied towards designing fusogenitic liposomes with cationic patches that showed enhanced fusogenicity compared to their homogenous counterparts. This work demonstrated that phase-separation can be applied to enhance the performance of cationic delivery liposomes. The last part of this dissertation seeks to use phase-separation to enhance cellular uptake of ligand-conjugated liposomes. Focusing on biotin-streptavidin binding, as a model system, biotinylated liposomes were designed to respond to acidic pH in tumor environment to undergo phase-separation and present their ligands in highly-dense patches. We are further investigating the application in cell studies. Together, this study provides an insight into the use of phase-separation to control the functionality of lipid membranes and it hence, offers new possibilities to overcome the shortcomings of current liposomal nanocarriers.Item Effects of Cytokines on Blood Brain Barrier in Neuropsychiatric Systemic Lupus Erythematosus(2023-04-13) Imran, ShanzehThe blood brain barrier (BBB) is a collection of blood capillaries that coordinate a series of metabolic, physical and transport properties that regulate interactions with vascular, immune, and neural cells, enabling healthy movement of molecules between the brain and the blood brain barrier. (1) Cognitive impairments as manifestations of neuropsychiatric systemic lupus erythematosus (NPSLE) occur in almost 40% of all people with systemic lupus (SLE). (2) There are certain types of cytokines that contribute to the disruption to the blood brain barrier. However, there remains a gap in knowledge where little to no research has been done on these biomolecules in the context of NPSLE, and the mechanism by which this phenomenon happens remains unknown. This research attempted to fill in the gap and work toward identifying clear markers of BBB breach in NPSLE, and identify the serum proteins and autoantibodies present in the blood that are predictive of BBB breach in SLE. The protocol of the experiment involves preparing blood brain barrier Transwell models using media and attachment factors, before adding the bovine endothelial cells and later astrocytes. The culture was then treated with the desired cytokines and transendothelial electrical resistance (TEER) was measured across the layer to confirm the integrity and permeability of the monolayer. The results implicate that the mechanism of the molecular basis of a blood brain barrier breach is difficult to determine in research from a co-culture of human astrocytes and bovine endothelial cells.