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Deformation and Failure Mechanisms of Cellulose-derived Advanced Structures
No full textCellulose, the most abundant natural polymer in the world, has attracted considerable attention recently owing to its superior mechanical properties, biodegradability, and low cost. Various cellulose-based materials have been developed, e.g., cellulose-based films (paper), hydrogels, aerogels, fibers, and composites. These materials feature a broad range of desirable functions such as optical transparency, high strength and toughness, programmable hydrophilicity and hydrophobicity, and electrical/ion/thermal conductivity, with the potential to be used in a wide range of applications such as energy storage, textile engineering, biomedicine, packaging, etc. This research proposal is devoted to advance the understanding of the deformation and failure mechanics of cellulose-derived sustainable materials, specifically, from the aspect of (1) deformation behaviors of cellulose-based functional structure design, including (a) 3D-printed deformable electrodes and separator for Lithium-ion batteries and (b) humidity-responsive, strong and smart cellulosic fiber actuators; (2) enriching the existing parameters to facilitate the mechanistic understanding of cellulose papers; (3) modeling the deformation and failure mechanism of chemically treated wood composite, such as (a) enhanced structural integrity of super wood (b) foldability of moldable wood versus. non-moldable wood (c) multilayered elastic wood for sustainable footwears; (4) failure mechanisms of super wood veneer tubes in the aspects of (a) failure mechanism of the unique petaling behavior of super wood tubes (b) a systematic finite element analysis on the geometrical dependency of failure modes and energy absorption performance of super wood tubes. (c) glue effects on the failure mode and energy absorption performance of super wood tubs under both static and dynamic loading conditions. Hopefully, the mechanistic understandings of cellulose-derived materials in current dissertation will shed light on developing a variety of structural applications for a more sustainable society
COORDINATED TRAFFICKING OF HEME TRANSPORTERS BY CARGO SORTING COMPLEXES IS ESSENTIAL FOR ORGANISMAL HEME HOMEOSTASIS
No full textHeme, an iron-containing organic ring, is a vital cofactor responsible for diverse biologicalfunctions and is the major source of bioavailable iron in the human diet. As a hydrophobic and
cytotoxic cofactor, heme must be transported in a highly controlled manner through membranes
via specific intra- and inter-cellular pathways. However, the genes and pathways responsible for
heme trafficking remain poorly understood. Unlike other metazoans, Caenorhabditis elegans
cannot synthesize heme but requires heme for sustenance. Thus, C. elegans is an ideal animal
model to identify heme trafficking pathways as it permits organismal heme homeostasis to be
directly manipulated by controlling environmental heme. Heme is imported apically into the
intestine by HRG-1-related permeases and exported basolaterally by MRP-5/ABCC5 to extra-
intestinal tissues. Loss of mrp-5 causes embryonic lethality that can be suppressed by dietary heme
supplementation raising the possibility that MRP-5-independent heme export pathways must exist.
Here we show, by performing a forward genetic screen in mrp-5 null mutants, that loss of the
vesicular cargo sorting Adaptor Protein complexes (AP-3) fully rescues mrp-5 lethality and
restores heme homeostasis. Remarkably, intestinal heme accumulation due to mrp-5-deficiency
causes a concomitant deficit in the lysosomal heme importer HRG-1 abundance and localization.
Loss of both MRP-5 and AP-3 subunits resurrects HRG-1 levels and localization, thus
underscoring the crucial role of HRG-1 in dictating mrp-5 mutant phenotypes. In the absence of
MRP-5, heme is exported by SLC49A3 homolog, a previously uncharacterized transporter. Live-
cell imaging reveals vesicular coalescence that facilitates heme transfer between the importers and
exporters at the interface of lysosomal-related organelle. These results define a mechanistic model
for metazoan heme trafficking and identifies SLC49A3 as a promising candidate for heme export
in mammals
A critical review of pre-post surveys designed to measure student epistemology in undergraduate science courses
No full textThe epistemology of science students, i.e., their beliefs about the nature of the knowledge they are learning, about what they have to do to learn it, and about how they will use that knowledge, often plays a powerful role in what they learn in their science courses. This perspective paper provides a broad overview of the theoretical frameworks, designs, and applications of online pre-post surveys that are available to assess the potential shifts in epistemic perspectives in undergraduate science courses. We pay particular attention to a recent survey for biology courses called the Maryland Biological Expectation Survey (MBEX). The MBEX was developed to probe four epistemic themes that are closely aligned with the Vision and Change initiative for reforming undergraduate biology education. This review is intended to inform STEM teachers about the availability of online epistemological surveys for evaluating the epistemic effects of their courses. These surveys can also help STEM education researchers readily evaluate how different pedagogies, classroom contexts, and other features of learning environments affect the epistemic perspectives of science students
Supporting Movies for Single-Particle Visualization of Water Uptake of Organic-Inorganic Aerosols with In-Situ Transmission Electron Microscopy
No full textPALS 2025 : Deliverable 1A-5
No full textThis report serves as FTA TOD Planning Grant deliverable 1A-3, a Policy and Process Framework for
Equitable Placemaking. It introduces key ways arts and culture interventions can help achieve TOD
planning goals under this grant, which align with the Purple Line Corridor Coalition’s (PLCC’s) defined
fourth priority outlined in the 2017 Community Development Agreement: “Vibrant and sustainable
communities enhance health, culture, and a sense of place.” The report outlines how PLCC, leveraging its
partnerships with communities, public agencies, and faculty and student design capacity within the
University of Maryland, can support future creative placemaking work along the Purple Line corridor in
ways that reflect and fortify the strong identities of the neighborhoods along the line.This report serves as FTA TOD Planning Grant deliverable 1A-3, a Policy and Process Framework for
Equitable Placemaking. It introduces key ways arts and culture interventions can help achieve TOD
planning goals under this grant, which align with the Purple Line Corridor Coalition’s (PLCC’s) defined
fourth priority outlined in the 2017 Community Development Agreement: “Vibrant and sustainable
communities enhance health, culture, and a sense of place.” The report outlines how PLCC, leveraging its
partnerships with communities, public agencies, and faculty and student design capacity within the
University of Maryland, can support future creative placemaking work along the Purple Line corridor in
ways that reflect and fortify the strong identities of the neighborhoods along the line.https://drive.google.com/file/d/1jsoGDL4_9bonCdzJNGvpqqs_OwKdPfQp/view?usp=sharin
Intersectional effects of race and gender on first impressions of Black and White autistic adults
No full textNon-autistic adults often harbor negative attitudes about autism and show a reluctance to interact with autistic people. For autistic people with multiple marginalized identities, the compounding effects of stigma based on race and disability may worsen peer attitudes. This study investigated first impressions of Black and White autistic adults made by non-autistic observers. Autistic adults (N = 29) stratified by race (15 Black, 14 White) completed a videotaped semi-structured conversation, and non-autistic raters provided their first impressions of each participant. Black autistic people were rated as more likable and trustworthy, and raters endorsed a greater interest in interacting with them, compared to White autistic people. Evidence of intersectional effects of race, gender, and autism was also observed. White autistic men, but not Black autistic men, were evaluated less favorably than non-male autistic participants, with Black autistic men being evaluated more favorably on some items. These results suggest that the intersection of race and autism may, in some cases, counter stereotypes about Blackness and autism, and that holding multiple marginalized identities can modify the characteristics of peer stigma toward autistic adults.
Lay abstract
Many non-autistic adults have negative feelings about autism and may not want to interact with autistic people. For people who face more than one kind of discrimination, like being part of a racial minority and being disabled, a combination of racism and ableism might make others’ opinions even more negative. This study looked at how people’s race, gender, and how others judge them are connected when people view videos of Black and White autistic adults. In the first part of the study, 29 autistic adults (15 Black, 14 White) had a conversation with the main researcher, which was recorded on video. In the second part, people who were not autistic watched these videos and shared their thoughts about each person. The results showed that Black autistic people were seen as more likable and trustworthy, and the people watching the videos were more interested in getting to know them compared to White autistic people. The study also found that race, gender, and autism together influenced how people were judged. Black autistic men were often judged similarly to, or better than, non-male participants, while White autistic men were judged less positively than non-male participants. This means that having more than one identity that is discriminated against can change the ways that people view autistic adults, such as allowing Black autistic men to avoid common stereotypes.American Psychological Foundationhttps://journals.sagepub.com/doi/10.1177/1362361325138929
The Removal of the kdsD Gene and Its Effect on Phage Replication and Growth in Escherichia coli
No full textBacteriophages - viruses that lyse bacteria - are a promising alternative treatment to counter antibiotic resistance that warrants further research. We explored kdsD and kdsC , non-essential genes that contribute to the formation of the outer membrane of E.coli to investigate the effect of an impaired membrane on bacterial growth and viral replication. The kdsD gene is responsible for the formation of the arabinose 5-phosphate isomerase that catalyzes the production of KDO while kdsC turns KDO 8-P to free KDO through phosphorylation, these are able to help form the outer membrane.
We employed two-time point phage titer and plaque assays to quantify and compare viral replication in ΔkdsD, ΔkdsC and parent strain. Additionally, lysis curves were conducted to compare viral replication in parent strain and ΔkdsD. We also explored differences in bacterial growth between strains using a growth curve in LB and M9 minimal media. For lysis and growth curves, absorbances were averaged and compared between strains, phages, and media, respectively.
The comparative growth curve revealed no noticeable difference between the growth of the parent and knockout strain in LB media. When observing the lysis curve the parent strain and knockout in T4r showed greater lysis than in T2. When comparing the lysis of the parent strain to the ΔkdsD, the parent strain had a higher absorbance value than the knockout when exposed to a bacteriophage environment. This data suggests that the ΔkdsD would increase the viral replication and that the function of kdsD in the KDO synthesis plays a less significant and necessary role. Comparative plaque assay regarding ΔkdsC were also conducted and distinguished that phage grows more abundantly with ΔkdsC than with kdsD.
Additional research should be conducted to investigate why viral replication was greater in ΔkdsD than in the parent strain. Further exploration into the bacterial growth and lysis curves of ΔkdsC in comparison to ΔkdsD and parent could be valuable. The ΔkdsD observations indicate that using the gene in phage therapy may be as useful. Testing ΔkdsC and other genes within the KDO pathway could provide insight on the uses of those genes in phage therapy and even more efficient possibilities for phage therapy
Polysaccharides in Amyloid Aggregation and Hydrogel Mechanics: Insights from Molecular Modeling
No full textPolysaccharides are linear polymeric carbohydrates with wide-ranging functions in biological contexts and constantly emerging applications at the intersection of biomedical and materials sciences. They often participate in soft matter systems—multi-component systems with a propensity for self-assembly—ranging from simple household agar gels to complex biofluids like mucus. In this thesis, we examined overlapping yet independent cases of polysaccharide-related self-assembly with relevance to materials design for engineering applications and disease-related amyloid aggregation. A common theme among them is the inherent dynamics and polymorphism of self-assembled structures, which pose challenges to complete characterizations with experimental techniques. We addressed the knowledge gaps in the experimental literature with molecular dynamics (MD), a method of physics-based simulations of molecular motions. The conventional MD approach, also known as “atomistic” MD, where each atom of a molecule is explicitly modeled, is accurate but inefficient at sampling the timescales necessary for large dynamical changes like self-assembly. To overcome this limitation, we opted for a simplified MD scheme known as “coarse-graining”, where degrees of freedom of atomistic molecules are reduced by approximating their chemical properties. With this approach to molecular modeling, four case studies of polysaccharide-based soft matter systems were performed, and mechanistic insights were reported.
The first case study considered a pH-responsive hydrogel system composed of the polysaccharide chitosan, and an anionic surfactant. Experiments showed that the hydrogels had contrasting mechanical properties at the two pH extremes. Our simulations, which spanned atomistic, coarse-grained, and non-equilibrium MD, provided insight into the structural origins of these pH-dependent mechanical properties. Next, we showed that chitosan hydrogels inhibited the toxic aggregation of Alzheimer's disease-related amyloid-β by sequestering monomeric peptides throughout the hydrogel network. The inhibitory effect was minimal in dilute chitosan conditions where hydrogels did not form. The last two case studies focused on the influence of glycosaminoglycans, a class of polysaccharide that make up parts of the extracellular matrix (ECM), on amyloid aggregation. One was aimed at understanding how glycosaminoglycans enhanced amyloid aggregation far from the cell surface, the other at the role of glycosaminoglycans near the cell surface. In this way, we investigated two distinct microenvironments within the ECM, the biological milieu of many toxic amyloids. Concurrently, we investigated the aggregation of two different peptides, developed coarse-grained force fields for two different glycosaminoglycans, and collectively contributed to a transferable toolkit of force fields for the modeling of sub-cellular environments. We developed thermodynamic and kinetic mechanisms for the ability of glycosaminoglycans to enhance amyloid aggregation in both contexts. Highlights include demonstrations of how the bending of glycsoaminglycans mediated peptide aggregation. In addition to contributing basic scientific knowledge, these insights may inspire strategies for amyloid inhibition, rational hydrogel design, or other applications
THE INFLUENCE OF JAZZ AND ITS PREDECESSORS ON PIANO CHAMBER MUSIC AFTER 1920
No full textIn the early 20th Century, jazz music and its predecessors, such as blues, ragtime, and stride piano, began to gain widespread popularity among audiences. Their defining characteristics including syncopated rhythms, improvisation, call and response, polyphony, distinctive harmony, and unique timbre. Many classical composers were intrigued and captivated by these new types of music. Composers such as Maurice Ravel, Erik Satie, Darius Milhaud, Igor Stravinsky, Dmitri Shostakovich, and Leonard Bernstein, among many others, were drawn to jazz style and incorporated its elements into their compositions.
This performance dissertation explores how a range of these composers, including both classical and jazz musicians, integrated jazz elements into their works which feature the piano(s), highlighting the creative interplay between the two traditions.
Three recitals were prepared and presented respectively on April 6, 2023, November 14, 2023, and March 24, 2025, at Gildenhorn Recital Hall of the University of Maryland.
The first recital featured works influenced by blues and third stream. The program included the Violin Sonata No. 2 in G Major by Maurice Ravel, Three Preludes by George Gershwin, as arranged by Jascha Heifetz, and Points on Jazz by Dave Brubeck.
The second recital (lecture recital) featured works influenced by ragtime and stride piano. The program included The Garden of Eden and Graceful Ghost Rag by William Bolcom, and Café Music by Paul Schoenfeld.
The last recital featured third stream music. The program included The Cape Cod Files by Paquito D’Rivera, the Sonata for Clarinet and Piano by Alec Wilder, the Piano Concerto No. 2 and the Trio for Piano, Flute, and Cello by Nikolai Kapustin.
Recordings can be accessed in the Digital Repository (DRUM) at the University of Maryland
Development and Validation of Feature-Based Vision Algorithms for Autonomous Ship-Deck Landing
No full textThis dissertation investigates feature-based computer vision algorithms for ship-deck landing. These algorithms incorporate 2D, 3D, and stereo computer vision techniques. The vision algorithms were validated using camera and computer hardware integrated into a quadrotor aircraft. Each of the evaluated vision algorithms is capable of estimating ship-deck pose or ship motion in real-time using only on-board vision hardware.
First, a previously developed 2D feature-based algorithm was refined and experimentally characterized. The algorithm utilizes feature matching to estimate a ship-deck pose using a stored 2D reference image. Performance was compared for a realistic helipad reference image and a detailed, customized image. Experimental validation was performed for Sea-state 6 ship-deck motion simulated using a Stewart platform. Additional experiments were performed for visually-degraded conditions, including occlusion, glare, and low illumination, and free flight. The results indicated that while the algorithm can utilize realistic landing pad designs, a feature-rich, custom landing pad image is needed for good performance. With this customized reference image, the algorithm was found to accurately estimate the ship-deck pose across all test scenarios.
A 3D feature-based vision algorithm was developed. The algorithm is based on the structure-from-motion technique used in 3D computer vision, and is capable of estimating the pose of a known 3D object. A simplified 3D object was created to represent a ship-deck for experimental validation. The accuracy and computational speed of the algorithm were evaluated for different feature detectors. Experimental tests were carried out for Sea-state 6 motion. The results indicated good pose estimation performance, with comparable accuracy to 2D vision methods. Additional tests validated performance for visually-degraded conditions, specifically glare, occlusion, and low illumination, as well as free hover. The algorithm was found to be robust to occlusion and low illumination, but performance was reduced in severe glare.
A feature-based stereo vision algorithm was also developed. The algorithm can estimating the motion of arbitrary ship structures without prior knowledge of their visual appearance or geometry. Experimental results showed that the stereo vision algorithm is capable of accurately estimating the motion of a simulated ship. As the algorithm estimates motion between frames, an initial pose is necessary, and pose estimates will drift over time. A Kalman filter was used to fuse results from the stereo vision algorithm with the previous 2D feature-based algorithm, which provides full estimates of ship pose and does not suffer from drift. This fused algorithm was validated using a realistic simulated ship incorporating 3D structures and 2D flight deck markings representative of a DDG-51 type ship. The fused algorithm was evaluated for Sea-state 6 motion, large-angle motion, and free flight. Results showed very accurate pose estimation results for Sea-state 6 motion, but accuracy was reduced for the large-angle case. In the free-flight test, the fused algorithm relied heavily on the stereo vision algorithm due to failure of the 2D algorithm to detect the flight deck, but still provided reasonable pose estimates