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A novel heat pump cycle to enable the flexible storage and deployment of harvested waste heat in cold climates
Get PDFThe increasing desire for renewable energy and decarbonization demands a transformation in the way we manage thermal and electrical energy in residential HVAC systems. New regulations and an increase in renewable energy participation in our power systems will increasingly incentivize fully electric solutions, flexible loads and load reductions for consumers. A novel heat pump concept is proposed that integrates a PCM-embedded heat exchanger in the injection line of a vapor injection heat pump system. Waste heat may be harvested from drain water or similar source, stored in the PCM and then deployed to heat a residential space using this concept. A system model was constructed for the proposed system as well for two baseline cases. The model demonstrates that when waste heat is directly deployed to the injection line when the heat pump is active, the COP can be increased to 5.0 from the baseline of 3.6. The waste heat utilization in this case is roughly 28%. Waste heat utilization can be much greater when waste heat is harvested and stored in the PCM while the heat pump is inactive. The performance of the heat pump was also simulated during a discharge state however the results are not representative of the true performance due to model stability issues which will be resolved in future work. More work is needed to understand the performance of the proposed heat pump but initial results demonstrate that it has potential to enable significant load reductions in residential settings.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2026-02-19 without embargo termsThe student, James Wills, accepted the attached license on 2025-12-05 at 16:21.The student, James Wills, submitted this Thesis for approval on 2025-12-05 at 16:30.This Thesis was approved for publication on 2025-12-11 at 11:57.DSpace SAF Submission Ingestion Package generated from Vireo submission #23087 on 2026-02-19 at 18:29:4
Coordination chemistry of unusual oxidation states of nickel and palladium relevant to homogeneous catalysis
No full textCoordination complexes of Group 10 transition metals – nickel (Ni) and palladium (Pd) hold privileged positions in the realm of metal-mediated catalysis. Transition metal complexes containing these metals are some of the most active catalysts that have been developed for important areas including, but not limited to, cross-coupling catalysis, C-H activation, olefin polymerization, and cross-electrophile coupling. In addition, several metalloenzymes found in Nature that catalyze important small-molecule activation processes feature Ni at their active site.
The commonly accepted mechanism of Pd-catalyzed cross-coupling, the most well-developed technology among these processes, involves diamagnetic intermediates. However, over the past two decades, researchers have become increasingly interested in how nickel-catalyzed reactions differ, particularly because Ni undergoes one-electron (radical) processes more readily. Ni and Pd coordination complexes that contain a single unpaired electron (NiI, PdI, NiIII, and PdIII) are thus subjects of tremendous interest due to their fundamental electronic structure as well as their role as intermediates in the various classes of reactions outlined above. Understanding and controlling the reactivity of these ‘unusual’ oxidation states of Ni and Pd promises to expand their roles in various bond-breaking and bond-making processes catalyzed by such complexes. This is the central question that this thesis aims to answer, with the focus being on the chemistry of low-valent Ni and Pd compounds that have one unpaired electron.
The first part of the thesis presents investigations into the electrochemistry of Ni and Pd compounds supported by thiapyridinophane ligands that have been developed in the Mirica group. These ligands feature mixed hard-soft donors pairs. This feature was hypothesized to be critical for stabilizing both low and high-valent states that are relevant to reductive small molecule activation reactions – particularly the proton and carbon dioxide reduction reactions. Key contributions include the development of a small-molecule mimic of the redox-active Ni center of [NiFe] hydrogenase. The small-molecule model was shown to switch between NiI and NiIII via a C-H activation process, mimicking the enzyme’s key redox states. It was also an active electrocatalyst for proton reduction. Further modifications of the ligand design led to interesting Ni and Pd coordination chemistry, which helped in the identification a decomposition pathway in a moderately active Pd carbon dioxide reduction catalyst, observation of unusual properties and reactivity in Ni and Pd coordination complexes.
The second section of the thesis details the coordination chemistry of Ni-isocyanide complexes. Isocyanides are most commonly form coordinatively saturated, inert transition metal coordination compounds. It was found that simple, commercially available isocyanide ligands were capable of stabilizing dinuclear NiI complexes – a much sought after synthetic target in the catalysis community. Unlike existing NiI compounds, these dinuclear complexes display thermal stability and rapid ligand substitution reactivity. They can also function as catalysts or pre-catalysts for a range of cross-coupling reactions. These results transform the position of isocyanides as ancillary ligands in coordination chemistry to potentially privileged ligands in cross-coupling catalysis. Furthermore, the development of NiII precatalysts bound to pivalonitrile ligands is also disclosed. Overall, this section introduces the first general source of NiI in cross-coupling catalysis and expands the repository of NiII precursors available to the synthetic chemist.
Finally, defining the role of NiI in catalysis begets the question – can such radical chemistry be performed by Pd catalysts? One area where PdI intermediates have been routinely proposed is photoexcited Pd catalysis. This chemistry allows the activation of alkyl halides, substrates that are typically inaccessible to ground-state Pd chemistry due to competing β-hydride elimination. Yet, direct structural or spectroscopic proof of such intermediates are absent. The synthesis and characterization of Xantphos-ligated PdI complexes are described, which were shown to be critical intermediates in photodriven elementary steps involving Pd0 and PdII-methyl complexes. This intermediate demonstrates the role of paramagnetic states in Pd catalysis.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-12-01The student, Sagnik Chakrabarti, accepted the attached license on 2025-08-19 at 10:43.The student, Sagnik Chakrabarti, submitted this Dissertation for approval on 2025-08-19 at 10:50.This Dissertation was approved for publication on 2025-09-08 at 15:04.DSpace SAF Submission Ingestion Package generated from Vireo submission #22765 on 2026-02-19 at 18:45:1
Examining the development of disciplinary literacy practices within a junior high exploratory professional learning project
No full textDisciplinary Literacy, the ability to read, write, and think in ways characteristic of different academic disciplines, is a critical skill for students. Content area teachers, such as those in science, social studies, and math, often struggle with teaching these literacy skills, as their expertise lies in their specific subject area. The study examined how members of a Disciplinary Literacy Professional Learning Community, comprised of a literacy specialist and a social studies teacher, supported Disciplinary Literacy skill and strategy instruction, the specific factors that influenced their success, and the experiences and perceptions of the learning community members. Data included semi-structured interviews, Professional Learning Community meetings, and classroom observations that were gathered over the course of the 2022-2024 school years by the building principal who served as the analyst of the data. Findings revealed three themes: factors influencing the success of the Disciplinary Literacy Professional Learning Community; use of discipline-specific literacy strategy and skill instruction; and experiences and perceptions of learning community members. This research contributes to the understanding of how literacy specialists can effectively collaborate with content area teachers in a Professional Learning Community to enhance Disciplinary Literacy instruction. The findings have implications for improving teaching practices, enhancing student learning outcomes, and informing the design of professional development programs in literacy education.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-12-01The student, Melissa Zaniewski, accepted the attached license on 2025-11-19 at 12:17.The student, Melissa Zaniewski, submitted this Dissertation for approval on 2025-11-19 at 12:23.This Dissertation was approved for publication on 2025-12-01 at 10:55.DSpace SAF Submission Ingestion Package generated from Vireo submission #22900 on 2026-02-19 at 18:45:4
Enhancing knowledge distillation in large language models via domain adaptation
No full textDomain-Adaptive Pre-Training (DAPT) is widely used to improve Large Language Models on specialized domains, yet its interaction with knowledge distillation (KD) remains poorly understood. In particular, intermediate DAPT checkpoints are rarely analyzed, and the evolution of teacher uncertainty across such checkpoints has not been systematically studied. This thesis develops a unified framework to examine how DAPT reshapes teacher confidence and how these shifts influence KD performance, downstream performance and calibration. Using LLaMA-2-7B teachers adapted for 2,000, 5,000, 7,500, and 10,000 DAPT steps, together with Sheared-LLaMA-1.3B students distilled under four KD variants, we evaluate two biomedical QA benchmarks: PubMedQA and BioASQ. We analyze teacher entropy, entropy–performance correlations, and student Expected Calibration Error (ECE) across checkpoints.
Our findings reveal three key insights: (1) teacher entropy shifts moderately with deeper DAPT but redistributes most strongly over semantically informative tokens; (2) moderate entropy reduction yields the strongest KD gains for abstractive reasoning tasks such as PubMedQA, whereas extractive QA tasks benefit more from heavily domain-adapted teachers whose predictions are sharper and more concentrated, and (3) student calibration closely tracks teacher entropy, with sharper teachers generally producing better-calibrated models, though excessively low entropy can introduce calibration trade-offs.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-12-01The student, Xitong (Jacqueline) Zhang, accepted the attached license on 2025-12-04 at 12:24.The student, Xitong (Jacqueline) Zhang, submitted this Thesis for approval on 2025-12-04 at 12:35.This Thesis was approved for publication on 2025-12-08 at 16:07.DSpace SAF Submission Ingestion Package generated from Vireo submission #23060 on 2026-02-19 at 18:46:4
Modular synthesis for cooperative small molecule ligands and chemical education
No full textModular synthesis can be leveraged as both a synthetic strategy for accessing cooperatively binding small molecule ligands as well as a pedagogic framework for chemical education. Mimicking hemoglobin’s cooperative binding to oxygen stands as an unclimbed mountain in the field of protein mimicry despite countless efforts in developing cooperatively binding ligands and the reference to hemoglobin in those reports. 9,9’-bianthracene was determined to have the potential to serve as a cooperative scaffold given its rigidity and pseudosymmetry which allows the adoption of a global conformation to a higher energy state that prepays the enthalpic cost upon binding of a first equivalent of a guest. The coupling of function-infused building blocks enables the synthesis of a collection of model tetra-pyridyl bianthracene systems that do exhibit positive cooperativity. This result supports the notion that the 9,9’-bianthracene could serve as a scaffold for positive cooperativity if the pyridine rings are to be exchanged with metal-schiff bases complexes that are capable of reversibly forming µ-oxo bridges with molecular oxygen.
As a framework for chemical education, modular synthesis serves the role of reducing the barrier to entry in organic chemistry and enabling students to discover structure-function relationships with the assistance of data science tools. Across four courses, we’ve developed a sequence of activities that introduce students to fundamental techniques such as K-nearest neighbors, K-medoids clustering, modularization of target molecules to identify repeating bond-types, and optimization of molecular function by identifying high-performing building blocks. Students also get hands-on experience in the power of modular synthesis to perform a classic diazo synthesis, a modern Suzuki-Miyaura cross-coupling that leverages a general purification procedure that enabled the development of an automated small molecule synthesis platform, an aerobic Suzuki-Miyaura coupling that generates an organic photovoltaic candidate for them to characterize and compare to a ML model. At the end of the sequence as well as the end of this dissertation, Organic Chemistry II students were challenged to shatter the traditional research-education barrier by synthesizing a collection of kinase inhibitor candidates. One student was able to successfully synthesize a molecule that is not reported in the literature and that molecule is currently undergoing screening against over 80 cell lines in collaboration with the CELLerator platform at UIUC.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-12-01The student, Nolan Green, accepted the attached license on 2025-07-18 at 09:30.The student, Nolan Green, submitted this Dissertation for approval on 2025-07-18 at 09:33.This Dissertation was approved for publication on 2025-07-28 at 09:27.DSpace SAF Submission Ingestion Package generated from Vireo submission #22653 on 2026-02-19 at 20:07:4
Manganese-catalyzed C-H oxidation applied to the synthesis of complex molecules
No full textChemoselectivity remains a significant challenge in the field of undirected Csp3-H oxidation. The powerful oxidants required to functionalize these strong bonds often react with any oxidizable functional groups present in a substrate, furnishing undesired side products. Although there are many reports of applying C-H oxidation methodology to the total synthesis of natural products, the use of this chemistry has been largely limited in the context of complex and highly functionalized molecular scaffolds due to chemoselectivity issues. Significant progress has been made in this area to date with PDP catalysts, with recent advancements expanding functional group tolerance to allow methylene C-H oxidation in the presence of Lewis-basic nitrogen and electron-neutral aromatic functional groups.
This dissertation focuses on efforts to expand pi-system tolerance in PDP-catalyzed Csp3-H oxidation and to leverage this enhanced chemoselectivity to oxidize complex substrates and intermediates in the context of natural product and metabolite synthesis. A novel system for oxidizing methylene C-H bonds in the presence of ,-unsaturated carbonyl functional groups was developed and optimized, with the highest degree of chemoselectivity accomplished by changing the reaction solvent from acetonitrile to 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and running the reaction in the absence of the carboxylic acid additive that is necessary for reactivity in previously reported systems. A Hammett analysis suggested that these changes resulted in a shift to a mechanism involving more positively-charged intermediates. Together with inductive deactivation of the pi-system resulting from solvent hydrogen-bonding to the carbonyl oxygen, the epoxidation pathway that previously outcompeted C-H oxidation in molecules containing ,-unsaturated carbonyls was successfully shut down.
This method was applied to the total synthesis of platencin, a natural product with powerful antibacterial bioactivity. The expanded chemoselectivity enabled a key C-H oxidation step that established 2 of 3 stereogenic centers in the bridged tricyclic core of the natural product. This approach also furnished synthetically useful yields of two different oxidation products that were elaborated to novel platencin analogs, which were also found to exhibit antibiotic activity.
Additionally, experimental validation of a neural network-based site prediction model was performed. Target substrates that were not included in the training set were selected, synthesized, and oxidized; then the major oxidation products were identified to assess the model’s predictive capabilities.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-12-01The student, Alexander Gomez, accepted the attached license on 2025-08-01 at 19:42.The student, Alexander Gomez, submitted this Dissertation for approval on 2025-08-01 at 19:49.This Dissertation was approved for publication on 2025-08-07 at 08:14.DSpace SAF Submission Ingestion Package generated from Vireo submission #22746 on 2026-02-19 at 20:07:5
Characterization of carbon ablators for hypersonic thermal protection systems
No full textHypersonic entry of a planetary atmosphere is among the most demanding environments in engineering, where a vehicle's kinetic energy is rapidly converted to thermal energy, generating extreme heat and caustic chemical conditions that rapidly destroy even the most advanced materials. Surviving such an environment depends entirely on the thermal protection system (TPS). Ablative materials, which dissipate aerothermal energy through controlled decomposition, are a commonly selected TPS material, with carbon-based variants often preferred for their superior thermochemical performance at high temperatures. Understanding how these materials decompose during hypersonic flight is therefore essential for proper selection and sizing of the TPS, motivating the detailed investigation of carbon ablators presented in this work.
Ablation is a complex multiphysics phenomenon, with numerous coupled mechanisms, such as gas-material reactions, sublimation, and mechanical erosion, governing material response. While it is critical to understand their cumulative effect, it is equally important to isolate and characterize the role of individual mechanisms on ablation behavior. Toward this end, the present work details extensive experimental characterization of low-density carbon ablators, including FiberForm and Phenolic Impregnated Carbon Ablator (PICA), first studying their bulk response under entry-like conditions, then focusing on two key ablation mechanisms: oxidation and spallation.
Initial experimental bulk characterization of carbon ablatives was conducted in high-enthalpy inductively coupled plasma (ICP) wind tunnels. FiberForm and carbon fiber weaves were exposed to high-temperature plasma in the Plasmatron facility at the von Karman Institute for Fluid Dynamics, where surface temperature, in-depth temperature, and recession were measured in situ under varying heat fluxes and pressures. During testing, spallation - mechanical erosion of surface fibers and bundles - was observed, and post-test analysis revealed oxidative decomposition in-depth during lower-temperature cases. Additional high-temperature tests were performed in the Plasmatron X wind tunnel at the University of Illinois at Urbana-Champaign, assessing the response of various graphite grades under high-temperature flight-relevant conditions. To analyze the transport-reaction competition of atomic oxygen in the boundary layer, a Damköhler number model for plasma wind tunnel environments was developed and implemented, providing an essential tool for ground-to-flight condition matching and finite-rate chemistry modeling.
These experiments prompted closer study of oxidation - the primary mass loss mechanism for carbon TPS in air - and the influence of diffusion-reaction competition in porous carbon-fiber ablators. Micron-resolution in situ X-ray microtomography (µ-CT) was conducted on oxidizing FiberForm samples at elevated temperatures across a range of pressures, producing time-resolved 3D (4D) image data of carbon fiber decomposition, enabling measurement of porosity evolution, oxidation depth, and the dimensionless Thiele number. High-temperature cases exhibited surface-limited mass loss, governed by oxygen diffusion, while low-temperature cases showed uniform, reaction-limited oxidation throughout the sample. Despite seemingly benign lower temperatures, reaction-limited oxidation led to in-depth fiber weakening, spallation, and structural collapse, a phenomenon with critical implications for material integrity in-flight. Time-resolved thermal and mass transport properties were extracted using Porous Microstructure Analysis (PuMA) software, revealing surface-localized changes in diffusion-limited regimes and uniform volumetric evolution under reaction-limited conditions. Results were compared with a PuMA oxidation model, which showed strong agreement with experimental data.
Building on prior observations, material spallation was investigated in supersonic air and nitrogen plasmas produced by the Plasmatron X ICP wind tunnel at aerothermal conditions representative of atmospheric entry. Spalled particles from FiberForm and PICA wedges were tracked using high-speed imaging, enabling time-resolved analysis of spallation events. Tests in nitrogen revealed high variance in particle production over time, while tests in air exhibited steady particle release. Post-test microscopy and spectroscopy identified a disordered nitrogen-functionalized carbon precipitate that forms exclusively in nitrogen plasma. Under extreme conditions, this deposit decreased surface permeability, enabling subsurface pressure buildup and causing unsteady particle release. Spalled particle size was inferred from velocity data obtained via particle tracking, enabling estimation of spallation mass loss. Spallation was estimated to account for upwards of 45% of total mass loss for tests in nitrogen, underscoring its significance in anaerobic entry conditions. Results suggest that deposit formation, material orientation, and environment conditions collectively govern spallation behavior.
Collectively, this work advances the fundamental understanding of carbon ablator performance in extreme environments, offering data, methodologies, and physical insight to guide the design, qualification, and modeling of future thermal protection materials. These advances enable safer, more reliable planetary entry for both national defense applications and next-generation space exploration.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-12-01The student, Benjamin Ringel, accepted the attached license on 2025-12-03 at 21:17.The student, Benjamin Ringel, submitted this Dissertation for approval on 2025-12-03 at 22:18.This Dissertation was approved for publication on 2025-12-04 at 14:09.DSpace SAF Submission Ingestion Package generated from Vireo submission #23055 on 2026-02-19 at 20:09:5
Saints, spouses, spiritual brothers: A fresh perspective on queerness in early modern Russian Orthodox culture
Get PDFReview of: Nick Mayhew. Queerness in the Early Modern Russian Orthodox Church. Cham: Palgrave Macmillan, 2025. xv + 227 p., eBook ISBN 978-3-032-03679-7
Transient Groundwater Flow Model of the American Bottoms Aquifer, East St. Louis, IL
No full textIn collaboration with the Illinois Department of Transportation, researchers at the Illinois
State Water Survey’s Groundwater Science section developed a transient groundwater flow model of the American Bottoms Aquifer near East St. Louis, IL. This work built on prior steady-state modeling analyses from this same intergovernmental collaboration (Jones et al. 2020). The study area was the American Bottoms region within Madison and St. Clair counties. The aquifer is bounded by the Mississippi River to the west and by limestone bedrock bluffs to the north, east, and southeast. Major groundwater withdrawals started in the region in the early 1900s and peaked at around 110 million gallons per day in the mid-1960s, producing significant drawdown
in observed water levels at major pumping centers. During this time, many infrastructure improvements were made in the region, including the construction of major highway projects considering the then-current low water table elevations. However, as industrial withdrawals
began to decrease starting in the 1960s, groundwater levels rose, threatening infrastructure and endangering traffic on these vital thoroughfares. In response to the rising groundwater levels, the Illinois Department of Transportation (IDOT) installed dewatering wells along important
stretches of interstate to protect infrastructure in the area by removing excess groundwater. To improve understanding of the region’s hydrogeology and the impact of the dewatering wells on
the regional groundwater flow regime, groundwater flow modeling was completed using MODFLOW via the Python programming language.
Hydrologic conditions, such as river stage, recharge from precipitation, and evapotranspiration, were temporally varied to reflect empirical records of conditions. Mississippi
River stage was based on historic U.S. Geological Survey gaging station measurements, while precipitation and recharge estimates were incorporated from the Parameter-elevations Regression
on Independent Slopes Model (PRISM) from the PRISM Climate Group. Estimates of
anthropogenic groundwater withdrawals were derived from analog records of regional pumpage (pre-1980) and from Illinois Water Inventory Program (Wessman 2021) records of withdrawals (post-1980). Estimated pumping rates for the IDOT dewatering system were determined from
communication with IDOT technical staff, but detailed observations of exact pumpage are not, as of this report, being actively recorded.
Regional synoptic measurements of groundwater elevations were performed in the American Bottoms in 1966, 1971, 1977, 1980, 1985, 1990, and 1995. The transient model was calibrated manually to observations during these years. Overall, the model performed well with R2 values that ranged from 0.64 to 0.89, root-mean-square error values ranging from 3.78 ft to 6.25 ft, mean absolute error ranging from 2.78 ft to 4.23 ft, mean error ranging from -1.87 ft to 0.69 ft, and percent bias ranging from -0.48 to 0.17 % (typical water levels range from 375 to 420 ft amsl). There is also strong agreement between the monthly model results and a long-term groundwater monitoring site’s monthly data, with a calculated Nash-Sutcliffe Efficiency (NSE)
of 0.57. These model results convey that the model structure accurately reproduces typical hydrogeologic processes present in the American Bottoms Aquifer.
Model results suggest groundwater generally flows from east and northeast to west and southwest in the American Bottoms Aquifer (including in the vicinity of the IDOT dewatering system). Important deviations from this regional trend include areas where the aquifer is impacted by transient influences such as groundwater pumping or high stages on the Mississippi River. The model displayed responsive behavior to empirically observed changes in precipitation, stage of the Mississippi River, and groundwater pumpage.Illinois Department of Transportation (IDOT); Project 209
Youth Development Mentorship Guidebook
No full textThe Youth Development Mentoring Guidebook is a workbook designed to guide new 4-H youth development educators through experiences essential to their Extension work, under the guidance of a mentor. While the Guidebook is designed specifically for 4-H activities in Illinois, it can be used with minimal adaptation in other states and for other out-of-school time staff. The Guidebook contains twenty activities, each accompanied by guided reflection questions that allow the mentee to consider retrospectively how the activity aligns with their own job responsibilities