University of Illinois at Chicago
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Synthesis, Structure and Transport Properties of New Lanthanum-based Ternary Hydrides
No full textThe quest for room-temperature superconductivity has driven intense exploration of hydrogen-rich compounds, identified as prime candidates for achieving high Tc, though their stabilization typically requires extreme pressures above 150–200 GPa. This thesis investigates chemical substitution and ternary hydride design that can stabilize superconducting phases of lanthanum hydrides at reduced pressures while retaining favorable superconducting properties.
Four classes of lanthanum-based ternary hydrides were synthesized and characterized under high pressure using diamond anvil cells, synchrotron X-ray diffraction, laser heating, and electrical transport measurements. In La–Y–H systems, partial Y incorporation lowered the formation pressure of LaH10-type clathrates while preserving the hydrogen cage network. Synchrotron X-ray diffraction imaging with multi-channel transport revealed Y-stabilized cubic and hexagonal superhydrides persisting down to 136 GPa, with superconducting transitions linked to distinct structural domains. La–Al–H experiments revealed that Al-doping neither substantially modifies the LaH10 framework nor reduces its formation pressure. The (La,Al)H10 system provided a platform for advancing spectroscopic probes of superconducting hydrides. Most promisingly, La–C–H compounds yielded multiple polymorphs stable between 90–115 GPa, substantially lower than the stability range of pure LaH10 (>150 GPa). It is establishing a framework for carbon incorporation into clathrate hydrides and providing transport evidence of enhanced electronic conduction. Finally, LaH3−x and nitrogen-doped LaH3−xNy were explored near ambient pressure, where vacancy ordering and light-element substitution revealed new pathways toward metallicity and potential superconductivity without megabar compression.
Collectively, these results demonstrate that targeted chemical substitution, through rare earth alloying, metal-site doping, and light-element incorporation, systematically tunes the stability and superconducting properties of lanthanum-based hydrides. Although room-temperature superconductivity outside the megabar regime remains elusive, the findings outline a roadmap for future progress through multicomponent substitutions and refined synthesis approaches. This work advances both the fundamental understanding and the experimental toolkit required to move hydride superconductivity from spectacular laboratory discoveries toward practical, reproducible materials
Data-centric Approaches for Responsible Data Science
No full textThe abundance of data, coupled with recent advancements in computation, has revolutionized almost every aspect of human life. While the undeniable benefits of this evolution are evident and despite the promise to bring good to human life and society, data-driven technologies could instead become harmful if not used responsibly. These harms usually stem from the inherent biases within the data and ``an algorithm is only as good as the data it works with''; therefore, if not addressed promptly, biases could get amplified to the downstream tasks in the data science pipelines. Without addressing the bias issues, we cannot expect AI-based societal solutions to have equitable outcomes. To this end, the main theme of this study revolves around responsible data science and algorithmic fairness with a strong emphasis on data-centric approaches.
In this study, we firstly focus on data coverage as a data-centric approach for identifying and resolving the misrepresentation of minorities in data. We propose novel algorithms that identify insufficient data coverage across data with different modalities and use a lack of representation information to generate data-centric reliability warnings.
Secondly, we study entity matching—a foundational task in data integration—through the lens of group fairness. We introduce new fairness definitions for entity matching, conduct a broad empirical analysis of existing techniques, and propose efficient algorithms to identify unbiased datasets within large search spaces. Building on this, we develop a framework for auditing entity matchers, diagnosing underlying reasons of unfairness, and resolving the issues through human-in-the-loop exploration with an ensemble of matchers.
Thirdly, we revisit several classic algorithmic data structures and problems through the lens of group fairness. We propose FairHash, a data-dependent hashmap that ensures group-level uniform distribution across buckets and simultaneously satisfies three formal fairness notions. For frequency estimation, we introduce Fair-Count-Min, a sketch that guarantees equal approximation factors across groups using group-aware semi-uniform hashing. We also revisit the Weighted Set Multi-Cover problem, a fundamental problem with significant applications in group fairness and package recommendations. We show that when the size of the universe is bounded, improved approximation algorithms can be designed.
Ultimately, this dissertation highlights the pivotal role of data in achieving equitable outcomes and establishes a foundation for future work in responsible data science
Motor and Neurophysiological Effects of Ischemic Conditioning (IC) and Tele-Based IC in Chronic Stroke
No full textThis dissertation examines the influence of ischemic conditioning (IC) on motor and neurophysiological outcomes in individuals with chronic stroke. Using neurophysiological measures to evaluate corticomotor excitability and transcallosal inhibition (TCI), these studies tested whether IC and tele-based ischemic conditioning (tele-IC) modulate corticomotor activity and motor performance. A single session of IC revealed distinct enhancements in ipsilesional corticomotor excitability and ipsilesional-to-contralesional TCI, accompanied by improvements in paretic strength and motor control. These findings demonstrate the acute neuromodulatory effects of IC, though validation in larger cohorts is needed.
Building on these results, a novel tele-IC paradigm—comprising seven remotely delivered sessions over two weeks—was found to be safe, feasible, and effective for individuals with chronic stroke. The intervention showed excellent adherence, minimal adverse effects, and high participant satisfaction, along with promising gains in neurophysiological and motor outcomes. Specifically, two weeks of tele-IC enhanced ipsilesional-to-contralesional TCI, bilateral strength, and paretic motor control. Notably, approximately half of the participants exhibited substantial increases in corticomotor excitability and paretic knee extensor strength, allowing identification of a responder subgroup to tele-IC.
Collectively, these findings highlight the neuromodulatory potential of blood flow modulation, indicating that IC may serve as a novel strategy to promote neurophysiological and motor recovery post-stroke. By advancing mechanistic understanding of IC, this work underscores the clinical relevance of cyclical blood flow modulation to promote neuroplasticity and functional rehabilitation both acutely and across multiple sessions. Importantly, the heterogeneity observed among participants, particularly within the tele-IC responder subgroup, emphasizes the possible need for personalized approaches to neuromodulation.
Overall, this dissertation provides foundational evidence that both acute IC and multi-session tele-IC represent scalable, low-burden, and individualized neuromodulatory approaches to enhance lower limb motor recovery after stroke. These findings support the need for future randomized controlled trials with larger samples to optimize IC protocols, delineate responder profiles based on neurophysiological characteristics, and evaluate dosing, durability, and combination strategies to maximize recovery outcomes
Monte Carlo-Based Predictive Modeling of Geometric Defects in Cellular Truss Structures Manufacturing
No full textThis study investigates the mechanical consequences of geometric defects in additively man-
ufactured metamaterials, with a focus on truss-based architecture. The superior mechanical
performance of these architectures is due to their unique geometry and topology. Complemented
by structural periodicity, these mechanical metamaterials outperform conventional materials by
far, by supplying a high stiffness-to-weight ratio, high heat transfer efficacy, high toughness, and
superior energy absorption characteristics. However, manufacturing-induced geometric defects
perturb the periodicity of these structures and substantially degrade their mechanical perfor-
mance. In this study, we focus on four commonly occurring manufacturing-induced geometric
defects: strut waviness, missing or broken strut, wavy struts, and variable cross-section of struts,
and examine their effect on the bulk behavior of the structure.
To study the impact of defects, we picked ten representative topologies from the Stankovic
dataset based on varying mechanical characteristics. We developed a Monte Carlo framework
to stochastically distribute defects within these structural units, enabling systematic compari-
son between as-designed (defect-free) and as-manufactured (defective) realizations. Mechanical
property space for each topology is computed using numerical homogenization and finite ele-
ment analysis and is validated experimentally via micro-compression testing. To support scalable
studies, an automated data-generation pipeline is introduced that takes in nodal coordinates,
connectivity data, and cross-section information to synthesize families of defective geometries,
which are evaluated with our FEA pipeline to predict their non-linear response.
Complementary specimens based on triply periodic minimal surfaces (TPMS) and stochastic
lattices are also fabricated using selective laser sintering to catalogue the geometric defects
specific to the process and surface-based lattices and summarize the empirical findings. Overall,
the proposed methodology quantifies defect-driven variability in mechanical properties, identifies
defect-sensitive motifs, and provides practical tools and datasets for reliability-aware design and
process optimization of additively manufactured metamaterials
Older Adult Sexuality and Educational Needs of Nursing Staff in Nursing Facilities
No full textObjective: Sexuality and sexual expression are basic needs throughout the lifespan. For older adults living in nursing homes, sexual expression is often challenging. A limited body of research exists to understand nursing staff knowledge and perceptions of resident sexuality in long-term care settings. The aims of this study were to ascertain resident sexual expressions encountered by nursing staff, nursing knowledge and attitudes related to resident sexuality, and their perceived learning needs.
Methods: A cross-sectional study of nurses working in nursing homes was performed. A survey was developed that included both closed-ended and open-ended questions. Knowledge and attitude questions were drawn from an existing instrument (ASKAS). A web-based system was used to distribute the survey. Participants were recruited from facilities of various sizes, both for-profit and non-profit, and in urban, rural, and suburban areas. Emails were sent to administrators to distribute the survey to nursing staff. Descriptive statistics and thematic analysis were used to analyze survey results.
Results: There were 92 completed surveys, including 34 nurses (37%) and 32 nursing assistants (35%). Overall, 20 respondents (25%) had never received any training on older adult sexuality. Significant knowledge gaps were identified. Though many reported an awareness of sexual expressions by residents occurring, the majority had not personally witnessed any.
Conclusions: The results of this survey reaffirm findings in the literature that nursing staff are not receiving training about older adult sexuality in nursing homes. The study also identified knowledge deficits about specific aspects of older adult sexuality. This study, primarily with frontline nursing staff, found limited experience with older adult sexual expression in comparison to prior studies of nursing home leaders and administrators. This may reflect different workplace responsibilities and unique educational needs. Continuing education initiatives may be necessary to equip nursing staff with the skills needed to deliver individualized sexual health care to older adults in long-term care facilities
Development of a Lumbar Exosuit with Hybrid Active-Passive Support for Healthcare Workers
No full textThe prevalence of lower back pain and related injuries is high among healthcare profes- sionals. Nursing involves lifting, shifting, and repositioning patients, and many of these tasks do not allow proper lifting or bending biomechanics, increasing the risk of injury. Although exoskeletons have been developed to alleviate spinal mechanical loading, many solutions are heavy, bulky, uncomfortable, and require large motors and complex control systems. Addi- tionally, these devices mainly target industrial sectors such as manufacturing and construction, failing to address the needs of healthcare workers. To overcome these limitations, a soft lumbar support Exosuit was developed combining passive components with an actuation unit, resulting in a lightweight (2.1 kg), soft, and supportive device. The Exosuit comprises a motor-driven lever mounted to the upper back and connected to two elastic actuators extending to the upper thighs. Using real-time trunk flexion angle data from an IMU sensor, the motor modulates the lever position to adjust the tension of the elastic actuators to store or release energy dur- ing phases of a lifting motion. Preliminary experimental results showed an average reduction of erector spinae muscle activity by approximately 38% across four participants during lift- ing tasks, suggesting a significant decrease in lumbar muscle demand when using the Exosuit. These findings indicate that this device is a promising solution to reduce the risk of low back injuries among healthcare workers
Mechanisms of Translational Control
No full textThis work employs structural and biophysical approaches to investigate the fundamental mechanisms of translational control in ribosomes. Specifically, we examine the molecular basis of Sec stop codon suppression and insertion, as well as the phenotypic consequences of perturbations to this process. Additionally, we explore how ribosome-binding antibiotics, particularly the pleuromutilin and aminoglycoside classes, affect translation initiation and termination, integrating high-resolution ribosome structures with microbiological and biochemical analyses.
First, we used cryo-electron microscopy (cryo-EM) combined with biochemical assays to elucidate the mechanism of Sec recoding in the mammalian ribosome. Suppression of UGA is achieved through a complex involving the mRNA 3′ untranslated region (UTR) Sec insertion sequence (SECIS), SECIS-binding protein 2 (SBP2), the 40S ribosomal subunit, and tRNASec bound to eukaryotic elongation factor selenocysteine (eEFSec). Our results reveal a mechanism of Sec UGA recoding in eukaryotes that differs fundamentally from its prokaryotic counterpart.
Next, we investigated the consequences of inefficient Sec incorporation on human health. O-phosphoseryl-tRNASec selenium transferase (SEPSECS), an enzyme essential for maintaining the cellular selenoproteome, catalyzes the terminal step in selenocysteine synthesis. Autosomal recessive mutations throughout SEPSECS lead to reduced selenoprotein levels and cause progressive cerebello-cerebral atrophy (PCCA) in humans. We conducted detailed biochemical, functional, and structural analyses of 12 pathogenic SEPSECS variants. Our results provide an improved framework for understanding SEPSECS-related neurodegeneration and may aid in defining the role of selenoproteins in central nervous system development and maintenance
Development of Earth Abundant Metal-Catalyzed Reactions to Construct Heterocycles
No full textN-Heterocyclic scaffolds are
ubiquitous in natural and pharmaceutical
compounds, and their significance has driven
extensive efforts toward developing efficient
synthetic methods. Our group focused on
efficiently triggering C–N bond formation via
different reactive nitroso intermediates. My
research has been centered on the development
of new methods to (a) construct sp3-C–Nar bonds
from nitroarene and (b) explore the generality of
the deoxygenation to convert 1,2-oxazines into
pyrroles.
The exposure of ortho-substituted nitroarenes to
3 mol % of (4,7-MeO-phen)Fe(OAc)2 and
phenylsilane as the stoichiometricreductant
afforded six-or seven-membered N-heterocycles.
The scope of the reaction is broad and tolerates a
range of electron-releasing or electron
withdrawing substituents on the nitroarene, and
the ortho-substituent can be modified to
construct benzoxazines, dihydro benzothiazines,
tetrahydroquinolines, tetrahydroquinoxalines,
or tetrahydrobenzo-oxazepines.
A tandem cycloaddition/iron-catalyzed oxygen-
atom deletion reaction was developed to
efficiently construct N-arylpyrroles. Kinetic
studies revealed a first-order rate dependence in
catalyst, oxazine, and silane concentrations, and
an inverse kinetic order in acetate was observed.
Kinetic isotope effect measurements, and Eyring
analysis provided mechanistic insight to suggest
that N–O bond cleavage of the oxazine
intermediate is turnover-limiting and occurs via
a highly ordered σ-bond metathesis transition
state.
Lastly, I discovered a new method to access
medium-sized rings via carbene intermediates
from N-tosylhydrazones
Unitary mechanical metamaterials with embedded one-qubit logic
No full textA class of lattice metamaterials characterized by a transfer matrix that updates polarization of a static sinusoidal displacement wave along a material coordinate in accordance with a unitary transformation is conceptualized. Specific material designs are discussed where the unitary transfer matrix takes the forms of the commonly used one-qubit quantum gates, such as the Pauli-X, Hadamard and others, depending on the unit cell geometry. Also, polarization parameters of the displacement wave are shown to form a Pauli spinor, a two-component complex vector representing the qubit state. Unitary metamaterials can be realized in practice as certain planar structures, or 3D lattices in a state of deformation similar to the continuum plain strain. Their potential application in human-scale mechanical platforms for simulating the quantum computation logic is discussed.</p
Un/Commoning Pedagogies: Forging Collectivity Through Difference in the Embodied Classroom and Beyond
No full textUn/Commoning Pedagogies Collective are seven dancer-scholars who centre embodied anti-racist praxis in our teaching across the fields of anthropology, sociology, African American and Africana studies, gender, sexuality and women’s studies, dance, and performance studies. Since 2019, the Un/Commoning Pedagogies Collective has engaged in consistent, process-based collaboration around teaching, scholarship, movement practice, and collegiality. We have co-authored essays, facilitated workshops, and given talks and performances. We also share syllabi, strategies, stories, milestones, failures, resources, and friendship. This writing is rooted in our ongoing collaborations and documents a co-generation of knowledge about the possibilities and tensions of teaching with and through our full-bodied selves. Moving beyond the syllabus, we offer you a glimpse into our concerns, commitments, experiences, and strategies as movement educators. We invite you to participate with us in a process of un/commoning pedagogy through embodied practice, dialogue, and reflection.</p
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