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Emulsions stabilized by magnetic ellipsoidal particles: a lattice Boltzmann study
No full textSchiller, UlfPorous materials are important across a wide range of applications, including water filtration, catalyst supports, battery electrodes, and bioengineered materials. To accommodate a broader range of pore sizes and enable scalable fabrication with minimal waste, bottom-up synthesis techniques have gained increasing attention. Emulsion templating leverages thermodynamic or kinetically arrested structures formed by phase-separating fluids. Among these, bicontinuous interfacially jammed emulsion gels (bijels) are particularly interesting due to their tortuous and co-continuous microstructures. ☐ Bijels were first formed via thermally induced spinodal decomposition of partially miscible fluid mixtures in the presence of neutrally wetting particles. As the fluid domains coarsen, particles adsorb onto the interface until the interfacial area matches the total cross-sectional area of the particles, resulting in a jammed monolayer that locks the microstructure in place. Traditional bijel synthesis via thermal phase separation is not readily scalable as the cooling rate cannot be uniformly controlled, which reduces uniformity of the structure. However, newer techniques such as Solvent Transfer Induced Phase Separation (STrIPS) have been developed to address the scale up limitation/ utilizing the removal of solvent from a bijel casting mixture to induce phase separation. STrIPS allows for the decoupling of spinodal decomposition from temperature, allowing for greater material compatibility and tunable bijel shapes and microstructure through controlling the solvent exchange rate. However, the microstructure obtained is coupled to the casting mixture composition, and the flow rate during STrIPS. ☐ One promising approach to modulate bijel microstructure is through stimulus-responsive systems. Magnetic stimuli, in particular, offer a controllable and targeted mechanism. Earlier studies using spherical particles under magnetic fields showed limited microstructural changes. However, ellipsoidal particles can respond to magnetic actuation by tilting, leading to the multipolar capillary interactions between particles facilitating formation of particle chains or rings at interfaces. This phenomenon opens the door to controllable modifications in bijel microstructures using magnetic fields. ☐ This dissertation investigates whether constant magnetic fields can be used to control the microstructure of bijels stabilized by magnetically responsive ellipsoidal particles. To explore this, we employ a multicomponent Lattice Boltzmann Method coupled with a molecular dynamics representation of rigid particles and a dipole-based magnetic field model. The system is modelled on a water-2,6-lutidine bijel casting mixture stabilized by micron-sized nickel-coated polystyrene particles. We first examine the ability of magnetic fields to influence bijel formation by applying a constant field during spinodal decomposition of fluid mixtures containing disc-like, spherical, and rod-like particles. While no significant change in domain size is observed for spherical particles, bijels stabilized by discs and rods show slight increases in domain size and become anisotropic, as measured by tortuosity and directional domain size. ☐ Further analysis reveals that the coarsening rates become direction-specific for ellipsoidal particles, suggesting that jamming occurs anisotropically due to particle alignment with the magnetic field. This alignment, governed by the orientation of the magnetic moment relative to the particle’s long axis, also affects how particles arrange themselves at the fluid interface. Particle alignment to the magnetic field affects the curvature of the interface as particles with smaller cross sectional area are less disruptive to the hyperbolic interface shape. Topological examinations of the morphology, demonstrating that the number of interconnected channels in the system decreased over time and that the average channel sizes obtained follow the same trend as that of the domain size. These results highlight how particle shape and magnetic field interactions can be leveraged to guide bijel formation in a directional and controllable manner. ☐ Next, we examine the ability of bijels to undergo microstructure modification post formation. This has implications for applications like crossflow reactors and filtration systems, where reversible control over permeability and flow resistance is desirable. By incrementally increasing and decreasing the magnetic field on a bijel stabilized with rod-like particles, we observe that the microstructure can be modified post-synthesis. Domain size increases nonlinearly with applied field strength and remains altered even after the field is reduced, indicating that the structure remains in a kinetically arrested state.To probe this further, we evaluate field-driven coarsening in bijels stabilized with rod and disc-like particles. Upon field application, particles reorient, leading to anisotropic domains similar to those formed during synthesis under a field. The temporal evolution of microstructure involves increased particle ordering, interface alignment, and rearrangement, demonstrating a complex interplay of factors. Notably, the extent of domain size change is negatively correlated with the initial ordering of particles. ☐ Given that many magnetically responsive materials exhibit field-dependent rheological behavior (e.g., shear thickening in ferrofluids), we investigate whether bijels exhibit similar effects. Prior studies have shown that shear can induce domain coarsening and particle ejection in bijels. Additionally, emulsions stabilized by ellipsoidal particles exhibit reduced viscosity with increased particle ordering because aligned particles create less resistance to flow. In this work, we explore how magnetic fields and initial microstructure affect the shear response of bijels stabilized by ellipsoidal particles. As particle ordering increases, the viscosity and shear-thinning behavior decrease for bijels stabilized by disc- and rod-like particles. We also characterize that the yield stress is dependent upon the friction between particles that is a function of the arrangement of particles on the interface, affected by the application of magnetic fields. These results suggest that magnetic field-driven particle ordering can be used to tailor the rheological behavior of bijels, offering a strategy to reduce viscosity and modulate shear-thinning by controlling interfacial microstructure. ☐ In conclusion, this dissertation demonstrates that magnetic fields offer a viable and tunable method for controlling bijel microstructures both during and after synthesis, and it characterizes the constant shear response of magnetically responsive bijels. These findings lay the groundwork for developing adaptive, magnetically responsive bijels suitable for porous material templates or as a soft matter system for use in drug release or bioengineering applications.University of Delaware, Department of Materials Science and EngineeringPh.D
Engineering corner states by coupling two-dimensional topological insulators
No full textThis article was originally published in Physical Review B. The version of record is available at: https://doi.org/10.1103/PhysRevB.111.045403.
©2025 American Physical Society.We theoretically find that the second-order topological insulator, i.e., corner states, can be engineered by coupling two copies of two-dimensional ℤ2 topological insulators with opposite spin helicities. As concrete examples, we utilize Kane-Mele models (i.e., graphene with intrinsic spin-orbit coupling) to realize the corner states by setting the respective graphenes as ℤ2 topological insulators with opposite intrinsic spin-orbit couplings. To exhibit its universality, we generalize our findings to other representative ℤ2 topological insulators, e.g., the Bernevig-Hughes-Zhang model. An effective model is presented to reveal the physical origin of the corner states. We further show that the corner states can also be designed in other topological systems, e.g., by coupling quantum anomalous Hall systems with opposite Chern numbers. Our work suggests that interlayer coupling can be treated as a simple and efficient strategy to drive two-dimensional lower-order topological insulators to the higher-order ones.This work was financially supported by the National Natural Science Foundation of China (Grants No. 12074097, No. 11974327, and No. 12004369), Natural Science Foundation of Hebei Province (Grant No. A2024205025), Anhui Initiative in Quantum Information Technologies (Grant No. AHY170000), and Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800). The supercomputing service of USTC is gratefully acknowledged
LEFT HANGING: HOW FIRST WORLD COUNTRIES EXPLOIT LOOPHOLES IN INTERNATIONAL LAW AND LEGAL DOCTRINE IN ORDER TO SUBVERT THE RIGHTS OF REFUGEES AND ASYLUM SEEKERS
No full textenterThis paper conducts a comparative analysis of the policy actions of four advanced
industrial countries and their use of loopholes and other tactics to sidestep
international law regarding refugees and asylum seekers. Inspired in part by fieldwork
in 2024 working with refugees and asylum seekers in Denmark, the paper discusses
how the Danish “zero-asylum” policy and immigration system evades and corrupts the
intention of 1951 UN Convention Relating to the Status of Refugees. My subsequent
comparative research has demonstrated that these evasive and “deterrence” policy
tactics exist in other first-world countries. This paper focuses specifically on instances
in Denmark, the United States, the United Kingdom, and Japan. (The Japanese case
illustrates how this phenomenon is global and not specific to Western polities.) The
paper develops these four case studies, examining each country’s refugee policies in
practice, the relevant international legal sources and precedents, and the impact of
these practices on refugee populations. I situate these cases in a cross-country analysis
to expose a common pattern of exploited legal loopholes. My conclusions speak to
possible legal responses or solutions to mitigate this problem in the future and
safeguard the intentions of international refugee law.ente
Bioenergetics and habitat use of green-winged teal across the annual period
No full textWilliams, Christopher K.Green-winged Teal (Anas crecca; hereafter teal) have not been extensively studied in the Atlantic Flyway, presumably because of their stable population status across their range. However, many waterfowl managers in the south Atlantic Flyway manage for teal, as they are a numerous waterfowl species across the Carolinas. Therefore, a bioenergetic carrying capacity model could identify which habitat types provide the most calories for teal, as well as calculate the number of teal that the region could support. I created a bioenergetic carrying capacity daily ration model for teal in the coastal plain of North Carolina and South Carolina. I identified preferred teal foods from 16 published studies as well as identified food items found in 73 gizzards collected from hunter-harvested teal in North Carolina. One hundred and twenty three core samples and 312 sweep-net samples were collected across seven distinct habitat types including high marsh, low marsh/mudflat, freshwater, moist-soil impoundment, millet impoundment, rice impoundment, and corn impoundment to calculate food availability on the landscape for teal. I collected samples over early, middle, and late winter to assess caloric depletion through time. Millet, corn, and rice impoundments had high caloric availability to teal in the form of seeds and crops. High marsh and low marsh/mudflat had high animal caloric availability to teal, while freshwater and moist- soil impoundments had comparatively low caloric availability. Over winter, available energy in rice declined, but increased in low marsh/mudflat and high marsh, making it necessary to calculate carrying capacity separately for each time period. To identify energy expenditure, I conducted 429 instantaneous scan samples and used 17,358 accelerometry bursts from teal marked with GPS transmitters to identify behavioral proportions, combined with real-time weather data to account for thermoregulation. Based on instantaneous scan sampling, teal were feeding/swimming 72.6%, resting 8.32%, and flying 19.08% of the time. Based on accelerometry data averaged from teal at both sites, teal were feeding/swimming 51.93%, resting 46.83%, and flying 1.24%. I calculated daily energy expenditure as 140.75 ± 24.7 kcal/bird/day for instantaneous scan sampling, 143.3 ± 1.8 kcal/bird/day for accelerometry data from individuals marked at Mackay Island NWR, and 140.5 ± 1.8 kcal/bird/day for accelerometry data from individuals marked at Orton. Lastly, I used the National Wetlands Inventory spatial data layer, as well as two spatial data layers for saltmarsh and one spatial data layer for impoundments, to calculate available habitat for teal, and extrapolated energy at a landscape level. Using these predicted energy values combined with energy expenditure estimates, I estimated duck-energy days (DED) in our study area at various scales over the wintering period. Orton could support 2,171 teal during the early period, 1,655 teal during the middle period, and 3,361 teal during the late period. My study area of the Carolina Flatwoods region of coastal North and South Carolina can support 976,705 teal during the early period, 679,106 teal during the middle period, and 1,774,812 teal during the late period, suggesting that teal may not be food limited during the wintering period, although providing better quality habitat with higher calories in the form of impoundments may allow teal to be in better body condition going into spring migration in the form of carry-over effects, and may otherwise improve spring migration survival and breeding success. ☐ There is also a noticeable lack of previous telemetry studies on Green-winged teal across their range due to their small body size. However, recent technological advances have allowed for 10-gram GPS/GSM units to collect high-frequency GPS data on teal across their life cycle. I attached 74 transmitters to teal in North Carolina in 2021-2023 and collected GPS points across the nonbreeding, migration and breeding periods. I compared home range size and habitat selection during the nonbreeding period across our two capture sites and compared day/night habitat use and other metrics. The average 95% autocorrelated kernel-density estimate home range size of wintering teal was 2,638.9 ha for teal marked at Mackay Island NWR (N = 10) and 8,062 ha for teal marked at Orton (N = 23). Teal at Mackay Island NWR showed habitat preference for saltmarsh and moist-soil impoundments, while teal at Orton showed habitat preference for saltmarsh and corn impoundments. I also identified winter philopatry in teal returning to the capture area through banding returns or transmitter GPS data. Return rate for teal within 100,000 km2 of the original marking location is 42.0% for teal marked with transmitters (N = 7) and 47.8% for teal marked with bands only (N = 23). ☐ In addition, I identified migration stopover information for marked teal, including migration duration, migration stopover duration, number of migration stopovers, percent habitat used, and percent public land used, and compared spring and fall migrations. I identified spring and fall migration information for 48 and 12 teal, respectively. Teal had stopover sites in 19 U.S. states and five Canadian provinces. The average migration duration was 74.2 days (range: 40-133 days) and 51.0 days (range: 9- 127 days), respectively. The average number of migration stopovers was 11.2 stopovers in spring and 11.6 stopovers in fall. The duration of the stopover predicted the distance between the next stopover site. Teal that committed to long refuel stopovers (> 48 h) flew further to the next stopover site than teal that stayed at a short rest (< 6 h) or a short refuel (6-48 h) stopover site. Teal in the spring used habitats such as temporarily- flooded agricultural fields, hereafter sheetwater wetlands, as well as freshwater marshes, saltmarshes, larger waterbodies, and some impoundments, and habitat use differed among stopover duration categories. In the fall, teal used all habitat types except for sheetwater wetlands, and habitat use differed among stopover duration categories. Behavioral proportions across stopover categories were significantly different for both spring and fall migration. Thirty two point nine percent of spring migration stopovers and 56.8% of fall migration stopovers within the U.S. had at least one GPS point on public land. I identified frequent short-rest stopovers which lasted <6 hours during the night, often in temporarily-flooded sheetwater wetlands, indicating that this habitat may be important for migrating teal to rest and feed as they move across the landscape.University of Delaware, Department of Entomology and Wildlife EcologyM.S
Photonics for microwave radiometric sensing
No full textPrather, Dennis W.Microwave radiometric remote sensing has monitored the earth’s ocean and environment for decades to provide data for weather forecasting models. More recently, the wireless communications community has embraced the idea of infusing wireless networks with sensing capabilities to support new applications, such as beam management for millimeter wave communications and autonomous vehicle monitoring. ☐ This dissertation outlines microwave photonic sensing solutions and focuses on two separate sensing systems: a microwave photonic radiometer for atmospheric sensing, and a microwave direction-finder. The radiometer system uses a fiber-arrayed waveguide grating to optically process the microwave spectrum from 50-70 GHz, near the oxygen absorption peak. Unlike previous radiometers, the system densely samples a full spectral band instead of selecting discrete frequency bins. ☐ For beam localization, a microwave photonic direction-finding system is presented. The system detects the angle-of-arrival of active signals, such as individual transmitters. An antenna array receives the signals, which are then up-converted to the optical domain. A photonic integrated circuit (PIC) optically processes the signals to determine source positions. A star coupler replicates the effect of a Fourier transform lens to determine the angle-of-arrival. The architecture is receive-only and has extremely low latency thanks to analog beam processing in the optical domain. ☐ To further enhance the capabilities of the direction-finding system, a second PIC is integrated for the purpose of frequency detection. The arrayed waveguide grating (AWG) PIC, fabricated at Sandia National Laboratory, has a spectral resolution of only 0.97 GHz to enable spectral sensing. By identifying the frequency of received signals, the effect of squint can be mitigated in the direction-finder, allowing the system to operate over the entire Ka-band (26.5-40 GHz). The combined beam localization and frequency detection capabilities show promise for applications in integrated sensing and communications.University of Delaware, Department of Electrical and Computer EngineeringPh.D
Interfacial physics toward high-efficiency Ti3C2Tx MXene supported catalysts
No full text"At the request of the author or degree granting institution, this graduate work is not available to view or purchase until May 04 2026"--ProQuest abstract/details page.Opila, Robert L.Meeting future energy needs has driven a rapid expansion of research to develop efficient photocatalysts and electrocatalysts for energy conversion and storage. In this area, two-dimensional (2D) MXene materials, such as Ti3C2Tx, have emerged as a very promising class of novel materials with tremendous potential to advance catalyst technology, having energy-related applications in hydrogen, oxygen, and carbon dioxide electrochemistry. The unique combination of metallic conductivity, high surface area, and ability to enhance interaction between interfaces with catalytic metals and metal oxides make MXenes a very attractive support to enable high-performance electrocatalysts and photocatalysts. Our work demonstrates that the efficacy of Ti3C2Tx-based catalysts is directly correlated to the interface between MXene and an adjacent metal or metal oxide catalyst. These enhanced interactions promote significant activity in photochemical and electrochemical reactions, such as hydrogen oxidation, hydrogen evolution, oxygen evolution and CO2 reduction reactions. Theoretical calculations and experimental results have revealed the fundamental mechanisms underlying these processes, highlighting the critical role of Ti3C2Tx to facilitate charge carrier excitation, promote efficient carrier transfer, tailor electronic structures, and optimize reaction pathways. This work underscores the versatility and promise of 2D MXene materials as a platform to develop efficient catalysts toward meeting future energy needs. We expect our work to inspire further research and innovation in this field.University of Delaware, Department of Materials Science and EngineeringPh.D
Hot or Not? Implicit and Explicit Attitudes of Sexualized Profiles on Tinder
No full textThis article was originally published in Cyberpsychology, Behavior, and Social Networking. The version of record is available at: https://doi.org/10.1177/21522715251382736
This is the accepted version of the following article: Ellithorpe, M. E., Kunaish, L., & Wright, H. (2025). Hot or Not? Implicit and Explicit Attitudes of Sexualized Profiles on Tinder. Cyberpsychology, Behavior, and Social Networking. https://doi.org/10.1177/21522715251382736 which has now been formally published in final form at Cyberpsychology, Behavior, and Social Networking at https://doi.org/10.1177/21522715251382736. This original submission version of the article may be used for non-commercial purposes in accordance with the Mary Ann Liebert, Inc., publishers’ self-archiving terms and conditions.
© 2025, Mary Ann Liebert, Inc., publishersResearch on dating applications relies heavily on explicitly measured evaluations of potential partners; however, the quick swiping mechanism of Tinder and other popular dating applications may rely on more spontaneous evaluations. We asked heterosexual U.S. undergraduates (n = 135) to rate opposite-gender Tinder profiles using both an implicit reaction time task and explicit self-report. Men had more positive implicit evaluations of sexualized profiles compared with women. Men also showed an implicitly measured preference for sexualized profiles over nonsexualized profiles, while women showed the opposite preference. However, the genders did not differ in evaluation of sexualized or nonsexualized profiles in explicitly measured evaluations. This study highlights the value of using implicit measures when conducting research on mobile dating.There is no funding source for this project
Programmatic Development & Ecological Enhancement Within Shady Grove
No full textMission:
Facilitate the curation of a phased strategic plan for the future of Shady Grove and it’s surrounding areas
Goals:
Promote better stormwater management within the area
Increase the accessibility to accommodate all
Beautify the area around the outdoor amphitheatre
Objectives:
Accessibility -
Conform existing paths to meet ADA guidelines
Create opportunities for more of the site to be utilized
Strengthen gateways into the site
Stormwater Management -
Implement Stormwater Management Facilities across the site to improve rate of capture and improve infiltration
Expose the movement of water on the site to educate users and improve intrigue of site
Purposefully direct the flow of water to prevent flooding of nearby housing
Beautify -
Improve the biodiversity of the site
Protect the site against storm damage
Create a sense of space within Shady GroveWik, AnnaZimmmerman, Jame
Zeolite-Encapsulated Ni Catalyst for the Direct Conversion of Mono- and Polysaccharides to Ethylene Glycol
No full textThis document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Sustainable Chemistry and Engineering, copyright © 2025 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acssuschemeng.5c00915.
This article will be embargoed until 04/25/2026.We have developed a simple, scalable, postsynthetic treatment for the encapsulation of Ni nanoparticles inside MFI zeolites as size-selective hydrogenation catalysts. We show that size-selective sieving of glucose from glycolaldehyde by the Ni-MFI-type zeolites enables an improvement in ethylene glycol yield by minimizing sorbitol and mannitol formation. This property is applied for the direct conversion of glucose to ethylene glycol, which can achieve 63% yield with less than 2% sugar alcohols in batch operation at lower reaction temperatures than previously reported (170 °C vs 230 °C). This improvement in size selectivity and yield can be extended to polysaccharides. The impacts of catalyst loadings, temperature, pH, and substrate concentration were studied, and optimal conditions for high selectivity were identified for both glucose and starch.This work was supported by Orazov Lab start-up funds through the Department of Chemical and Biomolecular Engineering at the University of Delaware. The authors would like to acknowledge support from the Center for Catalytic Science and Technology (CCST) at the University of Delaware. This work has been patented under publication no. WO 2024/243137