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An In-DEPTH Mechanical Characterization of Articular Cartilage: Machine Learning Optimization of Stereo DIC Data
No full textArticular cartilage is a complex, spatially graded material. Understanding how the tissue’s mechanical behavior changes throughout its depth is important for understanding musculoskeletal pathologies and their possible treatments. This study aimed to classify the fibril reinforced poroviscoelastic behavior of porcine cartilage in a depthwise manner. To do so, unconfined compression testing was paired with stereo-DIC to generate depth dependent data. Data were used to make sample specific finite element models. These models were optimized through a machine learning pipeline that updated the material parameters of the governing constitutive models to best match the experimental results. Optimized material property results show minor variation in depth, contrasting much of prior literature that showed greater variation with depth. This work provides a framework for simultaneously characterizing multiple aspects of material behavior in spatially graded materials.NSF (CMMI BMMB 2225174
SNOWSHOE HARE DYNAMICS AT THEIR SOUTHERN RANGE BOUNDARY: CYCLIC EROSION AND ISLAND PERSISTENCE
No full textGlobal climate change has shifted seasonality, influencing species across multiple scales, from individual traits to community dynamics. I examined these effects on a winter-adapted mammal snowshoe hare (Lepus americanus) at its southern range boundary, a region expected to be vulnerable to climate change. Specifically, I investigated how southern range populations are responding to changing environmental conditions. I examined this across two distinct ecological scales. At the community scale, a 40-year analysis of mainland populations (44º–49ºN) in the Great Lakes region revealed a clear gradient of fading cyclicity, indicating widespread population destabilization likely driven by pressures from shifting seasonality. Additionally, I assessed a hypothesized refugium on Isle Royale National Park. At the population and individual scale, this island population was found to be large, connected, demographically stable, and cyclic, despite lacking the specialized predators thought essential for cycle stability. These results demonstrate how shifting seasonality drives both cyclic collapse and unique persistence at the southern range edge. By integrating analyses across scales from community-wide cycle dynamics to localized refugial stability, I examined both broad scale regional shifts as well as identified Isle Royale as a critical stronghold for the persistence of this climate-vulnerable species
Plot Finder: An algorithm for automatically detecting plots in UAV images
No full textField-level phenotyping is a foundational component of plant breeding but remains a time-and labor-intensive task. Recent advances in imaging sensors and unmanned aerial vehicles (UAVs) have enabled high-throughput data collection at the field scale. However, phenotypic analysis is typically conducted at the plot level, requiring individual plots to be accurately extracted from UAV imagery. Because field experiments often contain hundreds to thousands of plots, this extraction step has become a major bottleneck in UAV-based phenotyping workflows. In this work, we present an automated algorithm for plot extraction from UAV images. We evaluate the method across eight datasets spanning three crop types (corn, potato, and beet) and demonstrate that our approach outperforms existing methods
EXPERIMENTAL CHARACTERIZATION OF TRANSVERSE FRICTIONAL BEHAVIOR OF PORCINE ARTICULAR CARTILAGE INTERFACES
No full textArticular cartilage is the material covering the ends of synovial joints responsible for low friction articulation. Its multiphasic and inhomogeneous structure results in time-dependent tribological behavior. Osteoarthritis (OA) is the degeneration and wear of the articular cartilage, resulting in impaired joint biomechanics. Due to cartilage’s limited ability to repair, there is a large focus on regenerative treatments such as engineered or allogenic osteochondral implants to treat early to mid-stage OA focal defects. However, challenges in cartilage-cartilage and cartilage-bone integration between native and implant tissue can result in the formation of non-ideal fibrocartilage and adhesive or cohesive failure. While articular surface frictional behavior has been widely reported, to the best of the author’s knowledge, there is a lack of quantitative assessment on depth-wise frictional behavior. Under the framework of osteochondral graft integration, the objective of this study was to quantitatively assess the bulk transverse static coefficient of friction between cartilage-cartilage interfaces. To achieve this, a custom device was designed to independently apply normal and tangential loading parameters. Samples were loaded consecutively under two normal loads to evaluate the tangential load and coefficients of friction. The method was validated through an elastic rubber material and by qualitative comparison against established literature values. Qualitatively comparing the current findings to other published studies showed comparable values for rubber and cartilage. While the current study is along the transverse interface and prior studies are along the articular surface, it does serve as a benchmark to guide further device improvements and as a control against cultured cartilage explants. This study provides a foundation to advance understanding of the transverse interface of cartilage and its role in integrative repair of osteochondral grafts.NSF CMMI BMMB 22251
Meaningful Learning Experiences for Teachers and Students Alike: One School Year of Rivers2Lake Impact Stories
No full textThis report summarizes impacts on teaching and student learning through the Rivers2Lake Education Program. Over the course of one school year, teachers participating in the year long Rivers2Lake Education Program identified several significant impacts that influence their professional practice. Specific outcomes include:
• time spent connecting with nature,
• the value of local knowledge,
• growing confidence and commitment to trying new things,
• teaching support and introduction to new resources, and
• applications to multiple subject areas and standards.The Rivers2Lake Education program, based at the Lake Superior National Estuarine Research Reserve, provides meaningful professional development for teachers through transformative field experiences, yearlong mentoring, and co-teaching. It directly engages students in outdoor, local, and inquiry-based learning. Rivers2Lake provides tangible resources, field opportunities, networking, and support to classrooms through direct instruction and personalized collaboration with and among teachers. The program is relationship-based and demonstrates investment of time, energy, and resources into teachers and their students. Each school year since 2012, education staff from the Lake Superior Reserve has mentored a cohort of 5-17 teachers over the course of a whole school year to navigate together changes in seasons, outdoor teaching conditions, student development, curriculum units of all subjects, as well as teacher and student confidence.National Oceanic Atmospheric Administration's Bay Watershed Education Training Program (BWET) and NOAA's Office for Coastal Management sponsored this work in partnership with UW-Madison Extension's Natural Resources Institute
Diameter-Dependent Raman and AFM Assessment of Damage in Yttrium-Treated Films of Single-Walled Carbon Nanotubes
No full textConjugated polymer sorting is a widely used route to obtain semiconducting single-walled carbon nanotubes (semi-CNTs), but residual polymer wrappers after deposition can negatively affect surface chemistry, interfacial behaviour, and device performance. Yttrium-assisted purification treatment has been explored as a promising route for removing such wrapper species. However, effects of this purification treatment on different diameter ranges remain a mystery. This work evaluates the yttrium-assisted purification strategy and quantifies how the treatment impacts the structural integrity of different semi-CNT diameter ranges. Three PFO-BPy-sorted diameter windows are studied: CoMoCAT (6,5) (~0.75 nm), HiPCO (075-1.28 nm), and Arc Discharge (1.3-1.7 nm).
To enable reliable, diameter-dependent comparisons, a sample-preparation workflow is implemented to reduce substrate, atmospheric, and solvent artifacts in Raman analysis, including passivation layer and nitrogen encapsulation, which together reduce the as-deposited Raman D/G ratio by ~90%. Yttrium-treatment cycles performed repetitively reveal a strong diameter dependence: Arc Discharge semi-CNTs show no damage and even a decrease in the D/G ratio, HiPCO shows a modest increase, while (6,5) semi-CNTs exhibit a pronounced increase of ~400%. A quasi-quantitative comparison to literature is used to bound contributions from doping and strain, supporting defect addition as the dominant origin of the D/G ratio rise in the smallest-diameter tubes. AFM imaging shows no uniform nanotube segmentation or shortening behaviour across all diameters
Caring Together for a Baby with a Medically Complex Condition: A Guidebook
No full textParent guidebook for caring for a baby with a complex medical condition
NON-INTRUSIVE SENSING SITE SELCECTION AND START OF COMBUSTION IDENTIFICATION IN MULTI-CYLINDER COMPRESSION-IGNITION ENGINES
No full textThis study investigates the impact of sensor location on accelerometer-based sensing of combustion phasing for compression-ignition engines. Ten accelerometer locations were studied on a light-duty compression-ignition engine for a set of conditions with variations in engine load, speed, injection timing, and injection strategy. Start of combustion (SOC) was identified from the filtered acceleration signal using a previously developed approach. Each location was assessed using both signal-based metrics, including magnitude squared coherence (MSC) between block surface acceleration and in-cylinder pressure, as well as SOC outcome-based metrics, such as detection success rate. Results demonstrate that the mounting location has a significant impact on the ability to extract combustion phasing information from the accelerometer signal. Sensors mounted on the front face of the engine produced the strongest signals for an individual cylinder. For multi-cylinder sensing, side-mounted locations delivered the most reliable performance, with SOC detection success above 98 percent, defined as correctly identifying the acceleration peak most closely aligned with the corresponding pressure-derived SOC for each cycle. This work outlines a practical framework for selecting and evaluating accelerometer mounting locations, enabling broader use of accelerometers in engine platforms operating on a range of combustion approaches.
Building on the results of the location study, additional efforts examine non-intrusive combustion sensing performance and interpretation under operating conditions beyond steady-state, traditional mixing-controlled diesel combustion. Sensing during transient operation, alternative sensing hardware (including a low-cost knock sensor), and sensing during energy-
assisted compression ignition (EACI) operation are investigated. Together, these results indicate that non-intrusive SOCa sensing can be extended to production relevant hardware and non-steady operation, but that the hardest cases are those with rapidly evolving or multi-stage heat release. Low-cost sensing hardware can remain effective at strong locations, transient load changes drive most miss identifications, and assisted combustion changes both the signal strength and the meaning of the detected SOCa.Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-20-2-0181 and W911NF-25-2-0128
THE ROLE OF PROMOTERS IN THE ACTIVATION OF TS-1 CATALYST
No full textThe use of promoters in industrially relevant reactions is important to obtain higher catalytic activities and yields. However, the mechanism of promotion in reaction pathways is often unknown. Prominent industrial examples are the addition of potassium phosphate oxyanion salts and ammonia during the selective oxidation of propylene to propylene oxide over titanium silicalite-1 (TS-1) via hydrogen peroxide, also known as the HPPO process. Little attention has been paid to these critical additives in academic literature. According to patent literature, the addition of potassium phosphate dibasic (K2HPO4) enhances the rate of propylene oxide production over TS-1 in a methanol solvent, but the mechanism is unclear. Whereas ammonia is disclosed to increase propylene oxide selectivity, the mechanism is still debated. To obtain mechanistic insights into this activation process, we performed Attenuated Total Reflection Infrared Spectroscopy (ATR-IR) enabled with Modulation Excitation Spectroscopy (MES) to assess the activation enhancement at different salt concentrations. The use of MES enables spectator-free observation of the critical Ti-OOH intermediates stretching modes of the catalyst. We found that the formation of Ti-OOH intermediates increases as K2HPO4 content increases. Specifically, we determined that 100 ppm of K2HPO4 increased Ti-OOH intermediate species 10-fold versus an unpromoted system. Surprisingly, control experiments revealed the promotional effect to be driven by the phosphate anions instead of the potassium cations. Using breakthrough curves we find that the absorption of H2O2 within catalyst pores is favored at higher K2HPO4 salt concentrations. Hence, we propose phosphate anions work as H2O2-delivery vehicles to Ti centers within the zeolite matrix due to their capacity to buffer charge balances within the pores. In contrast to the ammonia system, NH3 ligates to Ti centers to change its structure to a pentacoordinated state, which avoids ring opening reactions of propylene oxide. This investigation provides a
fundamental molecular insight into the industrial production of propylene oxide and the relationship between promoting salts, basic additives, and zeolitic Lewis acid sites