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ELECTROCHEMICAL ENGINEERING FOR CARBON DIOXIDE CAPTURE AND CARBON DIOXIDE CONVERSION
No full textThe profound effects of global climate change on the quality of life in human societies are closely tied to the surge in greenhouse gas emissions from human activities since the Industrial Revolution. The Paris Agreement highlights the pressing need to significantly cut down these emissions, bringing carbon capture, utilization, and storage to the forefront. Electrochemistry-enabled carbon capture and utilization align perfectly with the worldwide electrification shift towards renewable electricity-driven industry processes and the ongoing decarbonization endeavors to reduce carbon emission in all industrial sectors. In this work, we introduced three investigations inside this direction for both electrochemistry-enabled direct air capture and electrochemical carbon dioxide/carbon monoxide reduction.
Firstly, the work presents a novel process for low-cost direct air capture enabled by energy-efficient electrosynthesis of acid and base. This process gathers the merits from the fast kinetics in hydroxide capture reaction and acid-carbonate neutralization, the low cost of recirculated inorganic salts, the high efficiency and low embedded emission of membrane electrolysis. We demonstrate both experimental results on energy-efficient acid base synthesis with our electrochemical system design and techno-economic analysis results for a levelized cost of one hundred and ten dollar per tonne carbon dioxide with cost-reduction potential towards less than one hundred dollar per tonne. The work then delves into the system design for a room-temperature carbon dioxide electrolysis technology produces sodium formate. By alternating between regular electrolysis and gas-phase regeneration electrolysis operations, the carbon conversion efficiency is markedly enhanced, exceeding ninety percent throughout the process. In addition, a two-week-long continuous operation was successfully demonstrated with this system.
Lastly, the work explores the development of a copper-palladium bimetallic alloy electrocatalysts for carbon monoxide reduction towards acetate. It was found that this alloy electrocatalyst can produce acetate at excellent activity, selectivity, and stability. A comprehensive kinetic study was carried out in this work and the experimental results along with computational calculations suggest that the asymmetrical carbon-carbon coupling mechanism plays a key role in the unique selectivity towards acetate. This work highlights how heteroatomic alloy surfaces can be tailored to enable distinct reaction pathways and achieve advanced catalytic performance beyond monometallic catalysts
Determining ‘The Why’ First: Using the Nonprofit Mission, Vision, and Values Statements Model to Reimagine the Undergraduate Music Theory Curriculum
Get PDFThe Department of Music Theory at the Peabody Conservatory of the Johns Hopkins University recently joined many other institutions across North America in reimagining our undergraduate curriculum. Following practices more commonly found in the nonprofit sector, we began this undertaking by crafting mission, vision, and values statements. These newly articulated ideals for our department then served as a lodestar, effectively guiding the rest of the curriculum review and revision. The process we effected created an environment that facilitated creative thinking while simultaneously engendering clear consensus among our colleagues.
In this paper, we—as co-chairs of the committee charged with reviewing the
undergraduate music theory curriculum—discuss the steps that we followed in this process, as well as the results. We believe that this way of organizing curriculum review provides a useful framework that other schools can mirror when they reassess their curricula. Thinking critically about why we teach specific topics helped us to clarify exactly what should be required in the new curriculum and what could be optional for the students. As a case study, we present our mission, vision, and values statements, as well as the new curriculum that these led us to create. In so doing, we illustrate how adopting this approach from the nonprofit sector and applying it to curriculum reform guided us in unexpected directions that have been broadly supported within the Department and the Conservatory as a whole
UNDERSTANDING THE UNIVERSE AND MYSELF
Get PDFIn this anthology, I explore topics in theoretical and applied physics connecting complex natural phenomena to philosophical questions and my personal experiences. I strive to create a deeper understanding of the Universe and how the world works while learning about myself in the process. My work contains reported news stories, explanatory articles, personal essays, and opinion pieces. From tiny subatomic particles to supermassive black holes, I cover a range of topics, including taffy, pianos, and situationships, connecting mundane everyday stories to extraordinary scientific concepts
Efficacy Study of the Catch Up and Read Tutoring Program in a Large Southwest District
Get PDFTeachers were trained as tutors for this reading intervention.Results of this evaluation show statistically significant positive evidence regarding the efficacy of CAR tutoring on elementary student reading achievement, with treatment students significantly outperforming matched comparison students on the NWEA MAP Growth and STAAR reading assessments. These overall findings clearly appear to meet criteria for “moderate evidence” (Tier 2) for Evidence for ESSA and evidence support “With Reservations” for the What Works Clearinghouse. Efficacy evidence was especially positive for Grade 1 students and Hispanic students, as well as for students who received bilingual tutoring instruction. In interviews, CAR tutors conveyed positive views of the program’s ability to enhance reading achievement in struggling readers, as well as provide important and usable support for all teacher
ARTIFICIAL METALLOENZYMES FOR ENANTIOSELECTIVE CATALYSIS
No full textDNA-based ArMs, which composed of the chiral scaffold of natural or synthetic DNA and DNA’s strong affinity for transition metal ions or transition metal complexes, have been introduced and investigated as highly enantioselective catalysts. Here, to locate the chiral active centers in the DNA-ArMs and further understand the mechanisms of DNA-ArMs on enantioselective catalysis, we designed a series of minimal sequences. A copper (II) complex of 4,4'-dimethyl-2,2'-bipyridine (dmbipy-Cu) bound to a short double-stranded DNA (dsDNA) molecule, consisting of only 8 base pairs with two contiguous central G•C pairs, serves as a DNA-based ArM, which displays remarkable catalytic activity with high enantioselectivity in aqueous environments. Moreover, through the conjugation of the DNA molecule with a hydrophobic tail, the resulting ArMs exhibit significantly improved enantioselective performance when operating within a methanol-water mixture.
Along with the efforts made with developing minimal sequences, nucleotides (e.g., adenosine triphosphate (ATP)) have been discovered to have the high affinity for Cu(II) and can function as chiral scaffolds for enantioselective catalysis. We found that ATP and other nucleotides can establish irreversibly bindings within the metal-organic framework (MOF) MIL-101(Cr). Furthermore, in the presence of copper(II) ions, the MOF-supported nucleotides exhibit extraordinary stability and reusability, enabling their effective role as enantioselective heterogeneous catalysts. Significantly, when compared to their homogeneous nucleotide-based counterparts, the MOF-supported nucleotide-based ArMs demonstrate notable enhancement in both activity and selectivity in certain cases. This impressive outcome highlights their potential as a highly promising and innovative class of enantioselective heterogeneous catalysts.
Last but not the least, we found that the self-assembly of dsDNA amphiphile was influenced by the position of the hydrophobic tails. The dsDNA amphiphiles with two tails at the same side form only ellipsoidal micelles, while in contrast, the dsDNA amphiphiles with two tails at the different side form different structures, including micelles, nanotapes and nanotubes. Combing the catalytic activity of dmbipy-Cu, the dsDNA-amphiphile ArMs can catalyze asymmetric reactions with enhanced reaction rate and improved enantioselectivity compared to the corresponding non-amphiphilic dsDNA-ArM both in aqueous solutions and in organic cosolvent-water mixtures
A PASSAGE FROM INDIA: LOCATING THE “LIMBO CROSSROADS” IN THE WRITINGS OF ALEJO CARPENTIER, V. S. NAIPAUL AND SALMAN RUSHDIE
Get PDFThis dissertation explores the notion of “limbo” in two novels of Alejo Carpentier, in conversation with writings by V. S. Naipaul and Salman Rushdie. It focuses on Carpentier’s El siglo de las luces (1962) and El arpa y la sombra (1978), Naipaul’s A House for Mr. Biswas (1962) and Rushdie’s The Moor’s Last Sigh (1995) and Quichotte (2019). The central argument – that the notion of “limbo” stems from the very act of colonizing, attaches itself to the colonized person’s sense of self, seeps into the very foundation of a postcolonial society and transcends even into a post-truth and posthuman future – is based on close reading of the chosen works through a vantage point nuanced by my own cultural heritage. Such a “limbo”, my thesis argues, stems from both the need to make sense of reality through a metanarrative and also the failure to create such a metanarrative. Without claiming any direct influence of these authors on one another, this study compares the selected texts of three authors from previously colonized geographies through the texts they produce.
The dissertation assumes two “limbo figures” in history and in literature – respectively, Christopher Columbus and Don Quixote – and takes the term “limbo crossroads” as meeting points for intertextual, intercultural, and interdimensional encounters of characters within the selected fictions and, by extension, of their authors. Though significant scholarship has treated each author separately, this dissertation proposes studying them together and, to synthesize such seemingly different authorships, it employs the terms “passage”, “limbo”, “purgatory”, “in-between” and “crossroads”. This study considers postcolonial, decolonial and Global South scholarship along with post-truth and posthuman thought and is indebted to Homi Bhabha’s concept of “in-between”, Gayatri Chakrabarty-Spivak’s essay “Rethinking Comparitivism” and Roanne Kantor’s latest scholarship on the influence of Boom writers on English-language South Asian literature
Opioid Overdose, Employment, and Rurality Among Women on the Eastern Shore of Maryland
Get PDFBackground: Drug overdose is the leading cause of accidental death among United States adults, driven in large part by opioid-related overdose deaths. In 2020, opioid-related overdose deaths among U.S. women in rural areas outpaced those among women in urban areas. Despite this, women who use opioids are rarely the sole focus of research or intervention, and even less is known about this population in rural settings. Further knowledge about the experiences of women who use opioids in rural areas could be used to create a better-informed public health overdose response.
Methods: In 2019, the “Statewide Ethnographic Assessment of Drug Use and Services,” or the “SEADS” project, conducted in-depth interviews with people who use drugs in order to characterize substance use context and existing service capacity for harm reduction across Maryland. I conducted secondary qualitative data analysis of SEADS data: I employed a subset of interviews with thirty-seven women who use opioids living on the Eastern Shore of Maryland to explore women’s experiences with opioid use and overdose in one specific rural context and consider how these experiences relate to other facets of their lives.
Results: Exploratory analysis revealed several overarching themes explored in depth across three manuscripts: in the first, I find women are knowledgeable about and willing to respond in bystander overdose scenarios, but encounter significant barriers due to their anticipation of negative consequences, especially in their interactions with first responders. In the second, I find women in all phases of addiction, treatment, and recovery encounter drug use-related and treatment-related stigma that serves to exclude women from means of formal employment and contributes to their socioeconomic marginalization. In the third, I find that several domains of rurality, including social interconnectedness, lack of anonymity, and scarcity of resources and infrastructure are meaningful context for women’s experiences of opioid use on the Eastern Shore of Maryland.
Conclusion: This research builds on what is known about the lives and experiences of women who use opioids. Taken together, findings support interventions to reduce barriers to emergency care for opioid overdose; promote programs and policies that seek to address barriers to employment for women who use opioids; and cater interventions that address opioid use and overdose to the unique conditions of rural environments. These findings may be transferable to other similar rural settings and advance what is known about the influence of rurality on opioid-related harms
ASSESSING THE PROVISION AND EQUITABILITY OF PRIMARY CARE IN A LOW-RESOURCE SETTING
Get PDFIntroduction: To inform policies to promote well-being and eliminate health inequities in all settings, this dissertation focuses on an often-cited necessity for population health and heath equity—primary care—by pursuing the following aims: 1) conducting a review of the literature on the impact of primary care features on health access inequities 2) investigating the association between primary care experience (PCE) and the likelihood of hospitalization for chronic ambulatory care sensitive conditions (ACSCs) & inequities in the likelihood of hospitalization for chronic ACSCs among adults in rural Bihar, one of India’s socioeconomically backward states; and 3) investigating the association between the quality of local primary care—measured as average provider competence—and an individual’s self-rated health (SRH) & inequities in SRH in rural Bihar, India.
Methods: The 1st aim uses the scoping review approach. The 2nd and 3rd aims analyze data collected through household and provider surveys conducted under a parent study set in Bihar, India, using logistic regressions to model the odds of hospitalization and poor SRH as a functions of PCE and average provider competence, respectively, including interactions with markers of inequity.
Results: Primary care interventions are largely associated with improvements along the health access continuum for disadvantaged and advantaged populations, oftentimes with greater improvements for disadvantaged populations. Better PCE is associated with reduced likelihood of hospitalization for chronic ACSCs among adults. Individuals in the poorest wealth quintile with better PCE experienced the largest drop in the likelihood of hospitalization, compared to higher wealth quintiles. Better quality of local primary care, beyond a threshold, is associated with better individual-level SRH, although improvements in SRH appear to inequitable by gender and age.
Conclusion: This dissertation provides support for the strengthening of primary care systems, particularly in LMICs to tackle the burden of chronic primary care sensitive conditions and health inequities. Findings also highlight the importance of ensuring that the local quality of primary care is of an adequate standard to promote population health. More studies are needed to evaluate the quality of primary care and the reasons behind inequities in access to primary care in lower income countries
Association between same-sex experience and prevalence of subclinical cardiovascular disease among U.S. adults, 1999 – 2004
No full textBackground: Previous literature has indicated higher levels of cardiometabolic risk factors and cardiometabolic-associated biomarkers among sexual minorities than heterosexuals. It is thus important to examine if there is a corresponding higher prevalence of subclinical cardiovascular disease among sexual minorities. No previous studies have examined the prevalence of subclinical cardiovascular disease among a representative population of adult sexual minorities. We hypothesized that persons reporting any lifetime same-sex experience (SSE) would have higher burden of subclinical cardiovascular disease than heterosexuals.
Methods: We conducted a cross-sectional study of 5,938 participants aged 20 to <60 years without cardiovascular disease in the National Health and Nutrition Examination Survey 1999-2004. We used multivariable logistic regression to evaluate the association of any lifetime SSE with elevated high-sensitivity cardiac troponin T (hs-cTnT), high-sensitivity cardiac troponin I (hs-cTnI), and N-terminal B-type natriuretic peptide (NT-proBNP), biomarkers of cardiovascular disease.
Results: The prevalence of SSE was 5%. After adjustment for confounders, we found no statistically significant associations between SSE and elevated levels of hs-cTnT, hs-cTnI, or NT-proBNP. Effect estimates for hs-cTnT were attenuated from the unadjusted model after adjusting for demographics (Model 1 OR 95% CI: 0.48 [0.23, 1.00]) and additional behavioral and cardiometabolic risk factors (Model 2 OR 95% CI: 0.48 [0.23, 1.02]). For hs-cTnI and NT-proBNP, respectively, there were no notable patterns from the unadjusted (OR 95% CI: 0.76 [0.34, 1.69]) to the adjusted models (Model 1 OR 95% CI: 0.78 [0.35, 1.73]; Model 2 OR 95% CI: 0.76 [0.33, 1.74]) and from the unadjusted (OR 95% CI: 0.68 [0.40, 1.15]) to the adjusted models (Model 1 OR 95% CI: 0.68 [0.42, 1.09]; Model 2 OR 95% CI: 0.66 [0.41, 1.05]).
Conclusion: Counter to our hypothesis, we did not find evidence to suggest that persons reporting SSE had a higher burden of subclinical cardiovascular disease. Future research is needed to characterize the burden of subclinical cardiovascular disease among sexual minorities using contemporary data collected from a sizable sample of older adults
Hierarchical Gradient Domain Vector Field Processing
No full textVector fields are a fundamental mathematical construct for describing flow-field-related problems in science and engineering. To solve these types of problems effectively on a discrete surface, various vector field representations are proposed using finite dimensional bases, a discrete connection, and an operator approach. Furthermore, for computational efficiency, quadratic Dirichlet energy is preferred to measure the smoothness of the vector field in the gradient domain. However, while quadratic energy gives a simple linear system, it does not support real-time vector field processing on a high-resolution mesh without extensive GPU parallelization. To this end, this dissertation describes an efficient hierarchical solver for vector field processing. Our method extends the successful multigrid design for interactive signal processing on meshes using an induced vector field prolongation combing it with novel speedup techniques. We formulate a general way for extending scalar field prolongation to vector fields. Focusing on triangle meshes, our convergence study finds that a standard multigrid does not achieve fast convergence due to the poorly-conditioned system matrix. We observe a similar performance in standard single-level iterative methods such as the Jacobi, Gauss-Seidel, and conjugate gradient methods. Therefore, we compare three speedup techniques -- successive over-relaxation, smoothed prolongation, and Krylov subspace update, and incorporate them into our solver. Finally, we demonstrate our solver on useful applications such as logarithmic map computation and discuss the applications to other hierarchies such as texture grids, followed by the conclusion and future work