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Investigating the Impact of Lewis Acid and Base Interactions on the Solution Processing of Metal Halide Perovskite Solar Cells through Molecular Simulation and Machine Learning Approaches
No full textSolution-processed metal halide perovskite (MHP) solar cells provide a unique cost advantage over existing solar cell technologies without comprising on the performance of the resulting thin film solar cell device. However, the morphology and solar cell efficiency of the resulting MHP thin film is known to be heavily influenced by the material’s constitutive components (A- and B- site cations, and X-site atoms) and the processing solvent used to prepare these films. As these effects remain poorly understood, studying the nucleation and early-stage growth of these materials in solution would provide much needed insight into the effect of solvents on the quality of the resulting MHP thin film.
In this study, we leverage first principles density functional theory (DFT) and molecular dynamics (MD) to quantify and elucidate the role of Lewis acid and base (LA-LB) interactions in the nucleation and growth of the final MHP material in solution. We revealed that the strength of LA-LB interactions in all-inorganic MHP solutions can be tuned via judicious selections of solvents (Lewis bases) and reagent salts (Lewis acids) guided by the Gutmann donor number (DN) and Lithium cation affinity (LCA). Specifically, the nature of the solvent (S-donor or O-donor) influences the strength of its interaction with B-site cation salts and the A-site cation in all-inorganic MHP solutions, with S-donor solvents preferentially binding to B-site species, while O-donors prefer interactions with A-site species. Moreover, selecting inorganic cations (Cs+) over organic A-site cations (MA+) which have a strong potential to hydrogen bond with the solution medium, can provide greater control over the formation of intermediate structures (i.e. iodoplumbates) in solution. Overall, we indicate that the selection of reagent salts and solvents impact the strength of LA-LB interactions in solution and could have strong ramifications on the species formed and properties observed at more macroscopic levels.
Lastly, we explore how Bayesian optimization algorithms can leverage our understanding of the Lewis acid and base chemistry governing the formation of MHPs in solution to locate optimal reagent salt and solvent combinations for producing higher quality MHP thin films. We leveraged PAL-SEARCH: our novel approach for Gaussian Process (GP) based Bayesian optimization that imposes a linear mean prior on a categorical domain while identifying useful physicochemical properties to represent the domain variables' design choices to accelerate materials discovery. It has been successfully applied to MHP solution processing domains and we believe its successes can be extended to other fields in material science and chemistry
DEGENERATING ÉIRE: THE LITERARY PRODUCTION OF EARLY MODERN IRELAND
No full text“Degenerating Éire” examines the emergences of an Irish national consciousness in both English and Irish literature of the 16th and 17th centuries. National consciousness is a historical abstraction that precedes political nationalist projects and seeks instead to revolutionize temporalities by reconceiving of historical events as evidencing a present community of people bound by this shared past. The production of a national consciousness is grounded in material conditions but made sensible in the realm of ideology. Thus, “Ireland” as a concept in the early modern period is produced and mediated in large part within the literary realm. As the production of a national consciousness precedes the reality of a nation, national consciousness as a structure of thought is not bound uniquely to the culture and cultural products that it temporally binds. In the 16th and 17th centuries we see both the Irish and English intelligentsia begin to conceive of an “Irish nation,” the Irish largely through reaction to the desolation brought forth by the Elizabethan conquest, and the English as a means to bound and administrate its new colony in the realm of political documents. National consciousness during the Elizabethan conquest is thus both a project of identity formation and of futurology.
In order to evidence its claims, my dissertation considers three interrelated archives: Irish poetry composed by the bardic elite, English political treatises composed by settler colonists and court officials regarding the administration of Ireland, and contemporary literature of the Northern Irish Troubles composed by Ulster writers in the midst of violent struggle against the English colonial regime. I begin by examining the ways in which Irish poetry deploys the elegiac form to make sense of what has been lost in the Elizabethan conquest by understanding the lost-object via national abstractions avant la lettre. With particular attention to the poetry of Eochaidh Ó hEódhusa, his students, and Fearghal Óg Mac an Bhaird, I theorize how material desolation and the collapse of an economic system foreground national consciousness as a way of transmuting a sense of destitution into future potential vis-à-vis the artificial construction of a national past as a byproduct of mourning. I then turn to English political treatises and histories composed by a number of English colonial administrators—namely, John Chaloner, William Gerrard, Humphrey Gilbert, Edmund Tremayne, and William Herbert—to demonstrate the ways in which historical and early ethnographic writing produce what I call the “epistemological function” of the Irish reform treatise where Ireland becomes a site of anxiety, formally distinct and yet constitutive of the English state. I conclude my study of English texts by turning to the locus classicus of early modern English political theory on Ireland, Edmund Spenser’s A View of the Present State of Ireland. By attending to its circulation as a manuscript and the editorial choices of its posthumous publication, I show how Spenser’s contemporaries read A View as a text of political philosophy and colonial theory, interpretable through the genre of historical writing and evidenced in part by his own poetry. I end by turning to the late 20th century and, specifically, literature composed during the Northern Irish Troubles in order to understand how the longue durée of Irish national identity formation that originates in the early modern period becomes a key political point for authors writing in the midst of violent resistance to colonial governance. I place Seamus Heaney’s North and his university lectures alongside Frank McGuinness’s historical play Mutabilitie and commentary on Shakespeare in order to demonstrate two fundamentally distinct modes of receiving the violence of the early modern period, one universalist and the other historicist, and their resulting politics
CELL THERAPY TO CHANGE SKIN IDENTITY; IMPROVING MOUSE FIBROBLAST SURVIVAL IN VITRO AFTER ISOLATION AND IN VIVO AFTER INJECTION
No full textLimb loss affects millions of people worldwide, and the use of prosthetics is a common treatment option. However, many patients using prosthetics experience pain and inconvenience at their stump site skin due to skin abrasions, irritations, and dermatoses. To address this issue, our latest study has shown a potential cellular therapy with ectopic volar fibroblasts inducing a conversion of skin identity of the stump site from non-volar to volar, ultimately making its skin more resilient to clinical symptoms by increasing epidermal thickness and resiliency. However, the low survival rate of the injected fibroblast, and the abnormal morphology of senescence developed in isolated primary mouse fibroblast cultures present a challenge for further study. In this work, we have investigated two methods to address each challenge stated above. First, we have demonstrated that injected fibroblast survival can be significantly improved by depleting papillary mouse fibroblasts with UV irradiation of specific wavelength range. Also, by testing different coating materials that are reported to serve important role in dermal extracellular matrix and alter fibroblast behavior in vitro, we have shown that coating culture dish with fibronectin can significantly reduce the formation of senescent giant multinucleated fibroblasts in primary isolated mouse fibroblast cultures
Developing Middle School Teachers’ Understanding of Equitable Mathematics Instructional Practices
No full textMathematics achievement scores at the middle school level in the United States have remained relatively stable during the last three decades. Additionally, opportunity gaps persist for some groups of students. A needs assessment revealed that middle school mathematics teachers in the Mid Town district held constructivist beliefs about teaching mathematics. However, teachers varied in the use of constructivist practices in their classrooms, demonstrating that teachers’ beliefs about mathematics instruction may not align with their instructional practices. Based on these findings, the researcher designed and implemented an intervention to engage middle school mathematics teachers in a virtual professional learning community (PLC) focused on developing teachers’ knowledge and use of equitable mathematics teaching practices. Four teachers participated in the study during an 8-week period in the spring. A mixed methods convergent parallel design enabled assessment of the intervention process and outcomes. Findings demonstrate that participants valued the PLC resources and planned to use the resources in future instruction. Additionally, participants valued the opportunity to meet with and learn from their colleagues and were open to learning new equitable teaching strategies. Participants demonstrated a desire to implement or increase their use of equitable teaching practices to improve instruction. Based on the classroom observation data, all participants demonstrated the use of equitable teaching practices in their instruction. Implications for practice and further research are discussed along with study limitations
DEVELOPING A METHODOLOGY TO ASSESS VISUAL PERCEPTION WITH THE INTRA-CORTICAL VISUAL PROSTHESIS
No full textThis thesis is devoted to adopting and improving conventional psychophysical experiments to understand visual perception with a visual prosthesis. Recent advances in Biomedical Engineering enable implanting of more than 100 penetrating cortical electrodes. Characterizing individual electrodes for such devices with conventional methods could be tedious and impractical. This thesis focuses on developing and validating methods required for the intra-cortical visual prosthesis (ICVP) to create a meaningful perception using a real-time head-mounted camera. The ICVP implant was tested in the first participant with blindness in 2022 in the USA. The methodology proposed for ICVP in this thesis was pre-tested with participants with the most successful epiretinal implant, Argus II.
In general, Argus II and ICVP have a common concept. The participant wears a head-mounted camera that captures the image in real time. A portable miniaturized computer processes the camera frames and assigns each electrode the correct pulse parameters. This information, along with the power required to drive the implanted electronics, will then be transmitted to the electrodes using a wireless connection, and the participant will have a visual percept related to the camera image in approximately real-time.
The first chapter of this thesis starts with how the visual system works. It reviews some important classical psychophysical experiments that contributed to a better understanding of the human visual system. Then it reviews previous work in visual prostheses. The second chapter compares different threshold testing methods to identify the minimum current amplitude that could create a visual percept with a visual prosthesis. Multiple modified methods were tested with the Argus II epiretinal implant and the preliminary results for thresholds of ICVP electrodes of the first participant was reported. In the third chapter, the just noticeable differences method for identifying the number of distinct percept strengths from an electrode within the available current amplitude range is proposed and tested with Argus II and ICVP implantees. In the fourth chapter, a relative mapping program is suggested to identify the location of the percepts elicited by ICVP. Lastly, the fifth chapter discusses the limitations and future directions of this thesis
Plastic bimoment determination for cold-formed steel open sections
Get PDFWorking paper providing methods for calculating plastic warping torsion bimomentThe warping torsion strength of cold-formed steel open sections can be much higher than first yield. Recent
developments in the prediction of warping torsion bimoment strength demonstrate a dependence on the plastic
bimoment magnitude. This paper explains elastic and plastic bimoment stress distributions, presents the calculation
of first yield and plastic bimoment magnitudes, and provides the derivation of plastic bimoment formulas for some
common shapes.N/
Oral History of Roxanne Raven Storm
No full textThis oral history about transgender experience in Baltimore was recorded as part of Vintage T, a public humanities project led by Monica Stevens, Jamie Grace Alexander, and Rahne Alexander and sponsored by Sistas of the “T” and the Winston Tabb Special Collections Research Center. Vintage T was launched in 2023 to document and archive the perspectives, strategies, and personal histories of trans individuals in Baltimore, thereby preserving valuable traditions within trans communities
Evaluating the Role of Nuclear Energy in Virginia’s Zero-Carbon Electricity Future
Get PDFVirginia faces unprecedented load growth due to data center development in Dominion territory, a phenomenon which significantly complicates the state’s commitment to a zero-carbon electricity mix and creates enormous risk for Dominion ratepayers. This paper seeks to present stakeholders with a clear sense of the benefits and challenges of meeting surging demand with and without new nuclear facilities. First, I analyze Dominion’s 2023 Integrated Resource Plan to demonstrate the scale of the demand surge and the exorbitant cost of non-compliance with state climate laws. While alternative plans are presented, I find that they ignore real-world factors like local solar opposition and the eventual retirement of the state’s extensive natural gas generation fleet and nuclear plants. Two theoretical portfolios are examined – one which meets Virginia’s 2045 demand with only existing nuclear, variable renewable energy (VRE), and battery storage; and one which incorporates new nuclear. The VRE-reliant portfolio provides material economic benefits, but presents a greater reliability risk and is significantly more land-intensive. I conclude that to meet state climate goals while meeting demand affordably, a) utility planning processes must be more transparent and inclusive; b) local solar bans should be eliminated, while preserving localities ability to consider proposals on a project-by-project basis; c) the state should not permit utilities to gamble on major new nuclear projects in the short-term, and d) community engagement and planning should begin for new nuclear facilities in the medium-term as the demand picture and the economics of new nuclear become clearer
PYRRHONIAN PRACTICE: PYRRHONIAN SKEPTICISM AS INVESTIGATIVE, SUSPENSIVE, AND THERAPEUTIC
No full textCan the Pyrrhonian skeptic be a genuine inquirer? Sextus Empiricus seems to insist that this is so - many scholars, both ancient and contemporary, have disagreed. The practice, these interpreters suggest, is aimed at a therapeutic end, not an inquisitive one, and the things that are required for inquiry are the very things the Pyrrhonist forgoes. I propose an alternative reading of Pyrrhonian skepticism, endeavoring to show that the three central elements of Pyrrhonian practice - the suspensive, the investigative, and the therapeutic - are consistent with each other.
In the first chapter, I lay out these three elements and the ways in which tensions between them emerge. I critique in detail one recent attempt to reconcile them. In its place, I propose what I call ‘arational Pyrrhonism’, in which rationality plays an ineliminable causal role in the Pyrrhonist’s move to suspend judgement, but not a normative role.
In the second chapter, I make the case that arational Pyrrhonism can help us understand what it means for the skeptic to engage in inquiry. To this end, I develop an account of inquiry based upon contemporary work in epistemology. This account consists in holding a certain kind of interrogative attitude and abiding by certain fundamental epistemological obligations.
In the third chapter, I raise an objection to my account which I call the Value Objection. I argue that there are a variety of things that make an inquiry valuable, some of which do not depend upon the production of beliefs. I look at these non-doxastic sources of epistemic value and argue that Pyrrhonian inquiry is valuable precisely because it develops these things.
In the final chapter, I raise a continuation of the Value Objection to these non-doxastic sources of epistemic value. I argue that the products of Pyrrhonian inquiry possess intrinsic epistemic value. Once we see what the fruits of Pyrrhonian inquiry are, Sextus’ therapeutic claims about Pyrrhonism look a great deal less implausible. Far from being inconsistent, the three aspects of Pyrrhonian practice - the suspensive, the investigative, and the therapeutic - harmonize with one another
ENGINEERING 3D NANOINTERFACES VIA MECHANICAL ASSEMBLY AND TOP-DOWN FABRICATION FOR ENERGY, DIAGNOSTIC AND CELLULAR APPLICATIONS
No full textThe emergence of wearable technology and implantable electronics has showcased new possibilities for personalized health monitoring. To achieve accurate measurements, it is critical to integrate health sensors on stretchable and flexible substrates that can form conformal contacts on any three-dimensional (3D) surface. However, conventional nanofabrication processes are incompatible with these substrates due to extreme experimental conditions.
Nanolithography is a crucial technique in nanofabrication that facilitates accurate nanopatterning of thin film materials and is essential for the development of modern electronic components. Standard nanolithography methods, including electron beam lithography, focused ion beam lithography, and extreme ultraviolet lithography, have demonstrated precise nanopatterning capabilities with sub-10 nm resolution. Nonetheless, these techniques are associated with high operational costs and limited throughput.
My research focused on the combination of nanoimprint lithography (NIL) and nanotransfer printing to create large areas of nanopatterned thin film materials on unconventional substrates. NIL is an ideal platform for parallel nanomanufacturing of nanopatterns in a cost-effective manner and can be further integrated with the roll-to-roll process. Through my work, I have developed comprehensive nanofabrication and bonding techniques for a range of materials, including elastomers, hydrogels, and living cells, that result in high yield and throughput.
In addition, my research explored various applications of these hybrid materials. Specifically, I created three-dimensional gold electrocatalysts that can manipulate the selectivity of carbon dioxide using pre-strained polystyrene substrates. I also bonded gold nanowires and plasmonic nanopatterns on elastomers for buckling of nanowires arrays and SARS-CoV-2 detection. Furthermore, I developed a biocompatible nanotransfer printing technique to generate functional nanopatterns on living cell