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On-Chip Configurable and Hierarchical Microvascular Model Development for Drug Delivery Investigation
No full textBlood vessels in tissues are a highly organized system consisting of vessel of different scales organizing in a hierarchical manner. By providing a conduit for hemodynamic flow, blood vessels constitute the main component of the circulatory system and mediate gases, nutrients, metabolites, and other immune components between the blood and perfused tissues during diverse physiological processes. Recent advances in vascular tissue engineering and bioprinting have enabled construction of vessels of different size and geometries. Despite the significant advances, no method that can control vessel diameters from small capillary to intermediate-scale vessels, as well as the spacing and patterning has been reported. Therefore, the main content of this dissertation (chapter 2 and chapter 3) focused on exploring an integrated method for constructing an in vitro hierarchical vascular network with controllable topography. In chapter 2, a method that can build hierarchical and perfusable vessel networks was developed. By providing flow stimuli and proper HUVEC concentration, spontaneous anastomosis between endothelialized lumens and the self-assembled capillary network was induced, thus a perfusable network containing vessels at different scales was achieved. With this simple method, an in vitro hierarchical vessel-supported tumor model was prepared and its application in anti-cancer drug testing was demonstrated. The tumor growth rate was predicted by combining computational fluid dynamics simulation and a tumor growth mathematical model to understand the vessel perfusability effect on tumor growth rate in the hierarchical vessel network. Compared to the tumor model without capillary vessels, the hierarchical vessel-supported tumor shows a significantly higher growth rate and drug delivery efficiency. To control the topography of the small vessels, an acoustic field was used to position the endothelial cells in microfluidic chamber 3. By combining acoustic alignment and microfluidic vessel-on-a-chip techniques, human umbilical vein endothelial cells were patterned into desired topography and a tunable vessel network was constructed in vitro. Then, the perfusability of the formed on-chip vessel network was validated by micro beads flowing. With subjecting to vessel morphological analysis and particle image velocimetry monitoring, it was demonstrated that the spatial distribution of initially suspended cells has a significant effect on the shape of the blood vessel that forms later, thereby affecting fluid connectivity within the vessel as well as hemodynamic distribution. Additionally, an earlier project concerns how the protein functionalized liposome can be used to kill circulating tumor cells in blood vessel is also included in this dissertation. Specifically, the binding kinetics of P-selectin glycoprotein ligand-1 (PSGL-1) and E-selectin conjugated on liposome and on rigid surfaces are investigated with Atomic Force Microscopy (AFM) in this work. The knowledge and experience about protein chemistry and experimental design were provided by this project, which prepared the author for the following research work. However, as it is less relevant to the on-chip tissue model construction, this work is covered in chapter 4
Pulsed Power Load Accommodation in DC Microgrids
No full textMicrogrids with pulsed power loads (PPLs) have attracted increasing attention in recent years. Since the high transient power characteristics of PPLs pose a great challenge to the stable operation of microgrids, the accommodation of PPL becomes one of the existing issues to be urgently addressed in microgrids. As a result, the control design of microgrids for PPL accommodation is also of great importance.Targeting the important but not well-studied problem, a lot of control methods have been proposed for both offline and online PPL accommodation strategies. But the existing control solutions lack consideration for the transient control performance and also have difficulty with model complexity and uncertainty, various system constraints, and achieving control optimality. Therefore, high-performance control methods are developed in the dissertation to overcome these drawbacks. Firstly, a model-based optimal state-constrained control approach is proposed for the online PPL accommodation in DC microgrids. The transient performance of the ESS charging and bus voltage regulation is enhanced. Meanwhile, the overall energy efficiency is improved through generation cost minimization. Further, the model-free deep reinforcement learning (DRL) based optimal control methods are proposed for both offline and online PPL accommodation. The proposed DRL solution directly learns an effective control policy for the complex microgrid and exhibits a significant advantage in handling the input, state, and even the ramp-rate constraints. The overall control performance of the microgrid with PPL is optimized in a model-free manner. Eventually, extensive case studies have been conducted to validate the effectiveness and advantages of the proposed control approaches
Use of Pele\u27s tears and spheres as an indicator of lava fountain height in Hawaiian volcanoes
No full textThough lava flows have presented the greatest hazard to human property during the mostrecent eruptions of Hawaiian volcanoes, lava fountains represent the source of the lava flows and an additional hazard which should be considered. Previous workers have identified the exsolved gas content of the magma in Hawaiian volcanoes to be the main determinant of lava fountain height. Here, methods are described to empirically derive a relationship between the modal diameter of vesicles within Pele\u27s tears and spheres and lava fountain height, using samples of Pele\u27s tears which were produced during the last eruptions of K?lauea Iki (1959) and Mauna Ulu (1969). The empirical relation follows the trendline Hmax = -2575d + 820, where Hmax is maximum lava fountain height and d is modal vesicle diameter. This empirical relationship may be applied to eruptions which were not directly measured or observed to assess long-term shifts in lava fountain heights and thus the exsolved gas contents of a volcanic system
Cinderella Foreclosed: Maternal Dilemmas and the Friend Fiasco in Nella Larsen\u27s Passing
No full textNella Larsen�s novel Passing (1929) is a tragedy of about two childhood friends, Clare and Irene, who unsuccessfully rekindle their friendship. This tension between the now adult women stems from Clare�s decision to pass as a white woman and both women�s unfulfilled longings for maternal kinship. Larsen�s subversion of the Cinderella framework reveals this insight about the novel. Like every Cinderella tale, Clare�s story begins with an austere childhood, but when the storylines diverge, fairytale form reveals the presence of a �mother wound� within the main characters. This revelation demonstrates the devastating legacy that prolonged violence and racism has done to the African American community by way of denial of Black motherhood/childhood to Black women. This thesis seeks to include Passing in the Cinderella compendium. This essay is the seed for a larger body of work still to come
Ensuring Young Children Have a Head Start: Transition Practices that Link Early Childhood Education Settings
No full textAttention has been given to early childhood education to provide access to high-quality learning experiences. Early Head Start (EHS) and Head Start (HS) facilitate early childhood development by providing intensive, comprehensive educational services for low-income infants and toddlers and their families. Ensuring a smooth transition from an infant/toddler program into preschool is critical, as adjustment challenges can cause a negative experience, making children less likely to be responsive to later school. Presently, EHS and HS do not have a tool to examine their use of transition practices. The National Early Childhood Transition Center (NECTC) investigated practices and strategies that enhance early childhood transitions. The NECTC created a survey of Transition Practices for programs to assess their use of transition practices. However, this survey is general in nature with a focus on examining if practices were present or not instead of frequency of use. The goals of this research project are to adapt the NECTC Transition Practices Survey for use in the EHS/HS context and examine transition practices used by EHS and HS staff and the interrelationship with variables. The newly adapted measure was called Transition Practices-EHS/HS. Participants included 179 EHS and HS educators in Pennsylvania that support the transition process for children who exit EHS and enter HS. Results indicated that the Transition Practices-EHS/HS is a reliable, single-construct scale. Furthermore, it was found that EHS educators (i.e., EHS classroom teachers and EHS home visitors) implemented a higher mean of transition practices compared to Other Professional roles. Results suggest the Transition Practices-EHS/HS may be utilized as a self-reflection tool for EHS and HS educators to examine the current use of transition practices. Implications for practice and future research are also discussed
The Relationship Between Awareness of Age-Related Change, Cognitive Functioning, and Psychological Well-being of Older Adults
No full textAwareness of age-related change (AARC) is a dimension of subjective aging that describes how older adults feel about changes in their own functioning, both positive and negative, that are due to growing older (Diehl & Wahl, 2010). Diehl and Wahl (2010) proposed a theoretical model that outlined the antecedents and outcomes of AARC in older adults, which included cognitive abilities and psychological well-being. The current study investigated the relationship between AARC, cognitive functioning, and psychological well-being due to their connection with successful aging. Specifically, a structural equation model was tested in which (a) AARC gains and AARC losses were hypothesized to predict both cognitive functioning and psychological well-being and (b) cognitive functioning was hypothesized to predict psychological well-being. An alternative structural equation model was examined in which cognitive functioning was hypothesized to predict AARC gains and losses, as specified in Diehl and Wahl�s theoretical model; both cognitive functioning and AARC were hypothesized to be predictive of psychological well-being. A sample of older adults aged 60 and older were recruited from Amazon MTurk, and an online Qualtrics survey was used to gather the data. The results indicated greater support for the first model, in which AARC predicted cognitive functioning and psychological well-being. Several direct effects were statistically significant. Specifically, AARC losses was negatively and significantly related to inductive reasoning, processing speed, and psychological well-being and was positively and significantly related to verbal memory, while AARC gains was positively and significantly related only to psychological well-being. The current study�s findings have implications for both clinical work and research. The results may inform the work of geropsychologists in their work with older adults to promote successful aging by highlighting aspects to consider within conceptualization and interventions, such as AARC, cognitive functioning, and PWB. Additionally, the findings add to the growing body of literature about how older adults� awareness of age-related changes (i.e., AARC) relates to other key variables such as cognitive functioning and psychological well-being that impact successful aging
Evaluation and Validation of COLA in Complex Deep Neural Networks
No full textDeep Neural Networks (DNNs) have achieved remarkable success in various applications; however, their performance can be significantly affected by hardware defects in specialized accelerators. The Error-Correcting Output Codes (ECOC) framework has been proposed to enhance fault tolerance by decomposing multi-class problems into multiple binary classification subproblems. Despite its potential, the ECOC framework faces limitations in maintaining clean accuracy and improving robust accuracy when subjected to hardware defects, primarily due to error correlation between networks. In this thesis, we evaluate the performance of a recently proposed error decorrelation framework, named COLA, which addresses the limitations of the ECOC framework. COLA primarily incorporates the Amplitude Adaptive Weight Orthogonalization technique to lower error correlation in shared layers and the Total Correlation based regularization technique to minimize output error correlation. We evaluate COLA on more complex networks, such as ResNet18 and ResNet34, using the Tiny-ImageNet dataset, demonstrating significant improvements in the performance of models employing the ECOC framework. Compared to the original ECOC model, the improved ECOC model with COLA achieves around 10% increase in clean accuracy and up to around 80% improvement in robust accuracy. However, due to the specific structure of ResNet networks, models with ECOC exhibit notably lower performance than the original networks, both with and without hardware defects. To investigate this issue, we explore the impact of shortcut connections on the ECOC model and found that the presence of these connections can increase the total correlation of the feature map, which may potentially have a detrimental effect on the performance of the model
Sustainable Energy Management for Electric Bus Fleets: Dynamic Route Assignment and Optimal Charging Scheduling with Solar and Energy Storage
No full textThis thesis presents mathematical models to optimize the depot charging of a transit electric bus fleet given route schedules. The total cost of electricity drawn from the power grid is minimized in the presence of solar (PV) generation and an energy storage system (ESS). A mixed-integer linear program (MILP) is proposed that allows for static bus-route pairs as well as more flexible and dynamic assignments of buses to routes. The models are tested on data from a transit agency in Santa Clara County, California, including time-of-use (TOU) grid prices, vehicle specifications, and solar generation capabilities. Results show both models achieve full solar utilization and consume less power during peak hours. Dynamic route assignment achieves an 11% reduction in operational costs and performs well over a range of parameters based on sensitivity analysis. Furthermore, the results demonstrate the effect of weather on operational costs and other operational strategies
Dynamic Integration of Solar Assisted Carbon Capture with Thermal Energy Storage for Flexibilization of Natural Gas Combined Cycle Power Plant
No full textA fast increase in power generation from renewable sources is creating the need for a larger contribution from power generation from other sources. This demands more flexible power generation systems, making energy storage a necessity to integrate flexible power generation with the grid demand. Thermal energy storage is a good option to be integrated with Rankine power cycles. Particularly, sensible heat stored in concrete offers the option for integration with power plants in a flexible and cost competitive way. This document reports research results for the development of a thermal battery cell (TBC) capable of operating at temperatures up to 425°C. The TBC integrates a concrete matrix, engineered to provide enhanced thermal and mechanical properties, and thermosiphon elements capable of dual action operation, engineered to enable charging and discharging on a single thermal battery unit. Components for the TBC were researched in the laboratory. Two integrated single-thermosiphon TBC\u27s with storage capacities of 1.5 kWhth and 10 kWhth and an additional 150 kWhth TBC were designed and tested. Efficient heat transfer to/from the storage media, was demonstrated in the laboratory. All three TBC\u27s were tested under several different charging and discharging conditions and proven to be resourceful. Test results demonstrate the feasibility of the concept to store sensible thermal energy in concrete between 300°C and 400°C, with fast charging and discharging performance provided by the thermosiphons, suited for power generation unit fast ramping. In the second part of this research, a typical NGCC plant equipped with PCC was modeled in Aspen Plus and validated against similar models generated by the National Energy Technology Laboratory (NETL), and then adjusted to match the conditions of a plant located at Poza Rica, Mexico. After validation of the NGCC plant model with PCC, heat integration options were considered where heat from the flue gas cooler, CO2 dryer, and CO2 compressor intercoolers was used for heating of feedwater or low pressure (LP) steam in the steam cycle. The model was further modified to include solar-assisted carbon capture (SACC), to offset the detrimental impact of the PCC system on plant operations. The use of parabolic trough solar thermal collectors for heating of the stripper reboiler in the PCC system was considered in the Aspen Plus modeling. It was found that by using solar thermal energy for PCC reboiler heating, the LP steam extraction used to supply heat to the carbon capture reboiler element could be reduced in flow rate or eliminated depending on the quantity of solar thermal energy available. Modeling showed that if 100% of the reboiler duty could be supplied via solar thermal energy, net plant power would increase significantly relative to the case without solar thermal collectors. The availability of the solar resource was also predicted for the target location in Mexico using the System Advisor Model (SAM) developed by the National Renewable Energy Laboratory (NREL). By coupling the modeling results from SAM with those produced by Aspen Plus, annual plant energy production for an NGCC plant with PCC and using solar thermal energy for reboiler heating was found. A final case was modeled in both Aspen and SAM, where solar thermal energy was used for LP steam heating. While this case has marginally better performance than the case where solar thermal heat was applied to the reboiler, the added complexity of this system outweighs the slight increase in net annual power generation. This modeling effort demonstrated that solar thermal heating of the stripper reboiler in an NGCC plant with PCC could meaningfully offset the detrimental impact of carbon capture on plant efficiency and power generation loss, offering an attractive renewable energy option to NGCC carbon mitigation
Geochemistry of fluids and gases in the deep continental subsurface and deep-sea hydrothermal vents: Abiotic and biotic interactions in extreme environments
No full textThe work presented in this dissertation provides insights into the geochemical landscapes of novel environments in the continental and oceanic subsurface. The physical and chemical properties of fluids in deep crustal reservoirs and deep-sea hydrothermal vents directly influence the habitability of these environments. Thus, this work could have implications for the origin and evolution of life on ancient Earth and elsewhere in our solar system. High-density brines and alkane-rich gases are sourced from deep crustal reservoirs that are hosted in Neoarchean bedrock in the Soudan Underground Mine State Park, Minnesota, USA. Methane (CH4) and C2+ alkanes and alternative electron acceptors (e.g., sulfate (SO42-)) are viable energy sources for microorganisms in the fluids, which flow freely from boreholes at a depth of 713.5 m below the surface. Reactions involving the oxidation of alkanes by SO42- and NO3-, the reduction of SO42- and NO3- by H2, and methanogenesis from CO2 and dimethylamine (DMA) are exergonic. This study presents the first quantification of DMA abundance in a Precambrian shield brine. Dimethylamine may be actively cycled to produce biological CH4 in Soudan\u27s fluids, based on favorable free energy for DMA-based methanogenesis (-?G) in kJ/mole, and little available energy per mass fluid (J/kgfluid). The observed low abundance of H2, coupled to C1-C4 abundance ratios and measured stable isotope values (e.g., ?13C, ?13CH3D) of CH4 and C2+ alkanes allude to a thermogenic origin for C1-C4 n-alkanes, with a minor addition of biologically produced CH4, perhaps from DMA-based methanogenesis.The high volumes of reduced ?H2S-rich hydrothermal fluid and oxidized SO42--rich seawater in hydrothermal systems generate oxidation-reduction (redox) boundaries that can produce intermediate redox-state sulfur species. These species may then be utilized by benthic biological communities. Thiosulfate (S2O32-) and bisulfite (HSO3- ) are present in mixed fluids collected from eight high-temperature (>250 ?) black smoker vents and two low-temperature (<10 ?) diffuse vents at 9°46-52\u27N on the East Pacific Rise. Equilibrium mixing models predict theoretical concentrations of S2O32- and HSO3- that compare well to measured compositions, for fluids that have experienced little seawater entrainment. The lack of dissolved oxygen (O2), relatively low abundance of Fe-minerals in samplers, and the thermodynamics of aqueous Fe speciation in fluids with little seawater entrainment suggest that S2O32- and HSO3- are likely not produced by ?H2S oxidation by O2 or Fe3+, nor by SO42- reduction by Fe2+. Rather, dissolved S2O32- and HSO3- in these fluids are more likely formed through the abiotic reduction of entrained seawater SO42- by H2 and/or ?H2S. If H2 is at sufficient concentrations in the hydrothermal source fluid, mixing models predict that O2 is exhausted and H2 controls redox chemistry in fluids that contain little admixed seawater, complementing these assertions. In fluids that have experienced a higher degree of seawater dilution, several processes may result in the production of S2O32- and HSO3- in measured fluids.In submarine back-arc basins and arc volcanos, acid-sulfate, black smoker, and hybrid hydrothermal vents emit magmatic volatiles that can affect habitability of the seafloor. Abundances of anions fluoride (F-) and bromide (Br-) and the stable isotope values (?37Cl) of chloride (Cl-) are used to determine the degree of magmatic volatile input in hydrothermal vents in the Eastern Manus Basin and Brothers arc volcano in the southwest Pacific Ocean. Several fluids measured in this study have Br/Cl ratios similar to that of seawater, while most F/Cl ratios are greater than seawater values, due to input of magmatically sourced HF or leaching of F-enriched bedrock. Acid-sulfate fluids contain Cl with the highest ?37ClCl- values, compared with hybrid and black smoker fluids. Enriched 37Cl is indicative of either a fractionation process, or an additional Cl source beyond the simple entrainment of seawater. Several studies report estimates of mantle ?37Cl and experimentally determined temperature-dependent fractionation factors for magmatic ?37ClHCl(g) and ?37ClCl(aq). Theoretical fractionation factors for magmatic HCl are too small to encompass all endmember ?37ClCl- values in acid-sulfate fluids observed in this study. Rather, elevated ?37Cl values in the acid-sulfate fluids may also reflect 37-enriched Cl supplied from the subducting slab