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Host-Guest Mediated Approaches for the Synthesis of Functional Multicomponent Nanostructures
Get PDFMulticomponent nanoparticles (NPs) exhibit enhanced properties due to synergistic interactions between their components. Increased interest in these materials has established an underlying need for precise techniques to synthesize them. In this work, spherical silver bromide (AgBr) NPs are evaluated as porous ionic hosts to drive a host-guest mediated synthesis of well-defined multicomponent nanostructures: phase-pure Ag|AgBr dimers. Investigations into the mechanism of the dimer synthesis reveal that symmetry breaking by formation of a single Ag phase is achieved by illuminating the AgBr hosts with UV light in the presence of L-arginine to reduce the Ag+ cation guests harbored within the AgBr lattice. The reduction process is found to be surface-specific and dependent on the association of L-arginine with the surface of the AgBr particle via displacement of a “co-ligand” in the NPs’ stabilizing ligand shell. We posit that this reduction mechanism is robust to any species hosted within the AgBr lattice. As such, we explore the ability to use AgBr as a host to localize precursors and drive the synthesis of multi-metallic alloy NPs by introducing Cu2+ into the AgBr synthesis. The Cu2+ is co-reduced with the Ag+, yielding alloy NPs with tunable percent Cu. This allows us to systematically examine how the properties of these particles, specifically catalytic performance, evolve with changes in Cu composition. Investigations indicate that the AgCu alloy nanoparticles exhibit improved selectivity for the carbon monoxide (CO) product in the CO2RR. Alloy NPs with as little as 5% Cu exhibit statistically significant Faradaic Efficiencies and partial current densities for the CO product at relatively mild overpotentials and high mass activity. This host-guest technique expands the library of existing approaches for synthesizing multicomponent NPs and provides a platform for exploring how these methods can be used to synthesize other complex materials
Towards non-invasive blood cell counting and analysis with oblique back-illumination capillaroscopy
No full textBlood is indispensable in human life. Proper perfusion supplies nutrients and oxygen, removes waste, facilitates immune responses, and transports vital signaling molecules to nearly every tissue of the human body. Laboratory-based analysis of blood is a critical component of modern clinical care, providing medical staff with crucial information about health and disease. Among these diagnostic and analytic tests, the complete blood count (CBC) is the most common. The CBC, like most other blood tests, is invasive. It requires phlebotomy and transportation to complex and expensive laboratory equipment for analysis. Often, when disease is suspected, a blood smear is also ordered, where blood is deposited as monolayer on a glass slide and further analyzed by a hematologist using microscopy. These two tests provide the cornerstone for the diagnosis of hematologic disorders such as anemia, leukemia, sickle cell disease, myeloproliferative disorders, and thrombocytopenia. The CBC and blood smear are precise and effective tools that have been developed over centuries, however their invasive nature and reliance on complex and expensive equipment poses problems for certain vulnerable patient populations. The immunosuppressed are at risk of nosocomial infection, neonates are at risk of iatrogenic anemia, and many patients in remote and low-resource settings do not have access to necessary laboratory equipment. Thus, a device capable of providing non-invasive blood cell counting and analysis would fill an unmet clinical need for a diverse group of patients. Such a device would need to probe blood cells flowing through capillaries and other blood vessels in vivo, ideally in a label-free manner for safest use in humans. The work presented in this dissertation provides the foundation for such a technology, a combined phase and absorption contrast microscopy technique called oblique back-illumination capillaroscopy. This technique enables non-invasive, label-free imaging of individual blood cells flowing through human capillaries with simple, relatively low-cost equipment. Combined with deep learning based computer vision algorithms, oblique back-illumination capillaroscopy promises a new chapter of hematologic analysis and biomarker discovery
Neuromorphic encoding of tactile stimuli to provide naturalistic sensory feedback in upper limb prostheses
Get PDFToday, prostheses rely on decoding user intention through measurement of neural or electromyographic (EMG) signals. The full potential of these sophisticated robotic devices cannot be realized without the incorporation of sensors that evaluate the environment and a way to seamlessly communicate with the user. Neural prostheses can enable this seamless communication by interfacing directly with the nervous system of amputees and stimulating the nerves in order to elicit sensations corresponding to the interaction between the prosthesis and the environment. To give naturalistic sensory feedback, the analog readings from sensors incorporated into the prosthesis must be encoded into the language of the nervous system: patterns of spiking activity. With the motivation of improving sensory feedback for amputees, this thesis explores how information from tactile sensors can be transformed into neuron-like (neuromorphic) spikes to be used for stimulation feedback. Computational models mimic biological processing to encode tactile stimuli as robust and efficient spiking representations. The output of these models are classified to verify the successful encoding of texture information as neuromorphic spiking activity. Beyond the application to upper limb prostheses, the neuromorphic processing and compression algorithms explored in this thesis can be used to improve sensory neurorobotic systems more broadly. Chapter 1 provides a brief overview of the thesis and the contributions of this work. Chapter 2 is a review of the field of biomimetic sensing and encoding in upper limb prostheses. Chapter 3 covers "neuromorphic encoding" of tactile stimuli to mimic biological mechanoreceptor activity and create scanning speed and contact force invariant representations of texture stimuli. Chapter 4 covers "neuromorphic compression" of tactile stimuli to create information-rich representation of sensory information in the spiking domain. Chapter 5 covers the development of a multimodal (touch and temperature) nociceptive withdrawal reflex in a neurorobotic application using a neuromorphic encoding model. Chapter 6 summarizes the thesis and points towards future research directions
SYNTHESIS OF FUNCTIONALIZED BORON & SILICON BUILDING BLOCKS FOR FUNDAMENTAL STRUCTURE-BEHAVIOR RELATIONSHIPS
Get PDF“Structure determines function.”
Comprising plastics, gels, textiles, medicine and more, polymer chains are abundant macromolecules essential to our modern way of life. For any application, it is prudent to engineer these materials with desirable properties. These macromolecular behaviors of polymers and connected polymer networks (e.g. dissolution, strength, configuration) begin with the molecular structure of their constituent building blocks.
This dissertation highlights efforts to design and understand novel monomeric building blocks, polymer macromolecules, and crosslinked networks through intentional molecular structure design and reactivity by exploring carbon’s lesser studied periodic table neighbors: boron and silicon. Chapters 1 and 2 discuss the utilization of an organoborane synthetic loophole to achieve a novel polymer amphiphile that holds value in the plastic recycling industry. Chapter 3 discusses the design of silane building blocks that paradoxically instigate breakage in individual polymer strands, but toughen crosslinked networks. Chapter 4 discusses the swapping of carbon for silicon in cyclic structures and the resulting structure deformation features
SCHOOL Yoga & Mindfulness Instructional Design Review
No full textThis design review evaluates the product from a broad instructional design perspective that includes the program design framework, content selection, design, and development, evaluation, and interface. As indicated in this review, the SCHOOL Yoga & Mindfulness program has achieved Tier 4 evidence, as set forth by ESSA (Every Student Succeeds Act).The SCHOOL Yoga & Mindfulness Program is a secular curriculum that is designed to promote social and emotional connections between learners, teachers, and their peers, as well as to build an empathetic classroom. SCHOOL (Smiling Calm Hearts Open Our Learning) has been implemented in Title I schools across the U.S. with a purpose to "foster pro-self and pro-social attitudes in youths and their teachers to enhance the motivation to learn together." The tie between yoga, mindfulness, and learning is grounded firmly in socio-emotional research methods, and SCHOOL methods are used to prepare learners for their academics. In addition, SCHOOL utilizes a trauma-informed approach that prioritizes mental health and wellbeing for learners who have experienced loss, feelings of isolation, and anxiety. Specific strategies include focused breathing, simple yoga poses, meditation, positive affirmations, and storytelling.SCHOOL Inc
What the Dead Witnessed: Clearing Black Knowledges in Jim Crow South Carolina
No full textHistories of the New Deal widely debate the meaning and costs of progress and raise questions about who “progress” benefitted. Notable works contend that the New Deal in the U.S. South failed to improve black southerners economic and political realities. This dissertation considers the spiritual, epistemic, and ecological dimensions of development by focusing on the Santee-Cooper Hydroelectric and Navigation Project in South Carolina from 1938 to 1942. During the construction of the infrastructural project in the Santee-Cooper basin, thousands of graves, acres of land, and hundreds of black families faced removal and flooding. This dissertation explores how removing the dead and the living becomes integral to rural development projects. “What the Dead Witnessed” illuminates how developers imposed their will onto the land and subjected black residents to ecological, spiritual, and epistemic violence.
The first part, “the Land,” examines competing uses and understandings of the land in the basin, which produced and reproduced different racial formations that made the Santee Cooper project possible. Chapter 1 details the role limestone and geological surveying played in the area to show how various encounters with limestone helped (re)orient racial subjectivities. By focusing on the Authority’s land acquisition process, Chapter 2 illustrates how black residents negotiated and conveyed property.
The second part, “the Dead,” focuses on the removal and flooding of over 8,000 graves belonging to enslaved Africans and their descendants. By detailing grave removals, Chapter 3 demonstrates how the process perpetuated and solidified racial formation. By primarily focusing on photographs and other visual depictions of black cemeteries, Chapter 4 explores the doubled process of inundation. On the one hand, the diversion of two rivers flooded many cemeteries, springs, and other sites of black ancestral memory. On the other hand, the images taken by the Authority inundated the archive with images of “abandoned” graves.
The last past, “the Living,” examines the project's aftermath. The Conclusion traces the resettlement process of 901 black families and considers how the project's violence continues to the present day
THINGS SEEN AND UNSEEN: A COLLECTION OF NOVEL CHAPTERS
Get PDFThis thesis includes eight chapters of a fantasy novel entitled “Things Seen and Unseen”. Rainflower, an otherworldly changeling who seeks to understand her origins and leave behind a bloody past, crosses over into the human world. Savina, a girl haunted by a spirit in waking and sleeping, is suddenly uprooted from her life when she and Rainflower are brought together. As they journey to a better home for Savina, they discover unexpected companionship in each other despite their differences. This novel explores forgiveness and the struggle against self-hate. The included chapters detail part of the beginning of Savina and Rainflower’s connection through themselves and other characters
WIRED GENERATIONS: NAVIGATING SOCIAL SUPPORT AND PARENTAL PERSPECTIVES IN STUDENTS’ SOCIAL MEDIA USAGE
Get PDFThe steadily increasing usage of social media among students has sparked intense debate among scholars and policymakers. Concerns among parents over children’s social media usage have escalated. This has prompted policymakers to take quick or even sweeping measures to mitigate perceived risks. Unfortunately, when taking these measures, research highlighting the advantages of social media usage is frequently overlooked and is overshadowed by the exaggerated harms of social media prevalent in media narratives that exploit parental anxieties for increased readership. This trio of studies aims to 1) understand the relationship between students’ social media usage and social support, 2) explore the potential impact of a social-cognitive experiment on altering parents’ perspectives on social media, and 3) investigate ways to help parents understand the emotions and experiences of adolescents during parental monitoring. The results in the first paper demonstrated a significant positive relationship between social media usage and social support for student populations. The second paper found marginal effects on changing parents’ mindset and opinions. Although altering parents’ perspectives on social media is challenging, fostering considerate approaches toward adolescents’ privacy and emotions within the realm of parental monitoring emerges as a viable strategy. The third paper presented a design that improves parents’ valuing of adolescents’ privacy. This collection of three papers not only provides some evidence supporting the benefits of social media for students but also serves as a foundation for designing large-scale interventions for adolescents and parents on the social media matters
INVESTIGATING E-LEADERSHIP TO MANAGE INSTITUTIONAL CHANGE AND INNOVATION IN HIGHER EDUCATION
Get PDFOver the past 40 years there has been a steady increase in the use of technology for teaching and learning in institutions of higher education (IHEs). The use of these technologies increased exponentially during COVID, and research establishes the critical need for individuals with specific skill sets to not only help facilitate and implement technology-enhanced teaching and learning, but to offer their unique expertise as e-learning leaders. Despite this need, there is very little research about what this type of “e-leadership” should look like and how it should be conceived within higher education.
This paper underscores the critical role of e-learning specialists in higher education, examining their impact on student and institutional success. The study addresses the lack of consistent roles and reporting structures for these professionals, hindering their ability to contribute to key institutional decisions. A needs assessment reveals limited influence despite crucial knowledge and skills, necessitating a reevaluation of leadership roles for e-learning specialists within institutions of higher education.
To address the gap in research related to e-leadership in higher education, the paper proposes a theoretical framework using shared leadership (SL) and adaptive structuration theory (AST) to understand and enhance e-leadership in higher education. Shared leadership emphasizes collaboration, trust, and empowerment, while AST explores the dynamic interplay between technology and leadership. Both frameworks highlight key components for effective leadership and technology integration in the rapidly evolving landscape of educational technology.
The proposed intervention study aims to implement a shared leadership model for a team of e-learning specialists, focusing on enhancing collaboration, employee engagement, empowerment, decision-making processes, and innovation. The intervention consists of four phases: education, team collaboration, implementation, and e-leadership. Data collection involves interviews to understand the structures used by e-learning specialists, identifying e-leadership competencies and dynamic processes within technology teams.
The paper concludes by providing a practical guide for implementing the proposed intervention and emphasizing the importance of improvement science in higher education. It advocates for the recognition of e-leadership as a distinct profession within the academic landscape, fostering collaborative efforts, knowledge exchange, and the establishment of clear competencies for e-learning specialists. The proposed study, grounded in a systems perspective, aims to leverage insights and enhance practices and processes in higher education through a comprehensive understanding of e-leadership competencies
Enhancing Wind Turbine Wake Modeling in Atmospheric Boundary Layers: Insights into Veer and Thermal Stratification Effects
No full textUnderstanding wind turbine wake interactions with atmospheric boundary layer (ABL) flows is essential for optimizing wind farm performance. This study focuses on modeling wind turbine wakes in ABL flows including realistic features like wind veer and thermal stratification. We investigate wind turbine wake physics using Large Eddy Simulations (LES) of wind turbines within ABL flows. The LES uses an established numerical solver using mixed spectral and finite difference discretization and actuator disk representation of wind turbines. The LES simulations are used to inform extensions of a previously proposed analytical model that describes the curling of yawed turbine wakes due to counter-rotating vortices. The original version of this model applies to truly neutral atmospheric conditions and entirely neglects wind veer and stratification effects. The main objective of this thesis is to integrate these additional physical phenomena known to occur in ABL flows, into wake models and test the results using LES. Initial results show that wind veer in a Conventionally Neutral Boundary Layer (CNBL) have a minor effect on the evolution of streamwise counter-rotating vortices, which contribute to wake deflection in yawed turbines. However, the wind veer introduces a sheared wake structure atop the curling due to yaw. To model this wind veer effect, a veer correction is proposed for the curled wake model. Computing this correction necessitates inputs from LES, rendering the model not fully predictive.
Recognizing the necessity of a self-consistent analytical wake model including veer and stratification effects, we develop a model for predicting the ABL’s vertical structure. This model provides predictions of streamwise and spanwise velocity profiles, ABL depth, surface cooling flux, friction velocity, and geostrophic wind velocities in conventionally neutral and stable ABL flows. The model's validity is demonstrated through comparison with a comprehensive LES dataset without wind turbines. This ABL model is integrated with the curled wake model to yield a comprehensive approach for modeling wind turbine wakes. Good agreement between the model predictions and LES of turbines with varying yaw angles in diverse atmospheric conditions is demonstrated. Notably, the model gives better predictions for power loss due to wake interaction between turbines