University of Southern Mississippi

Aquila Digital Community
Not a member yet
    17686 research outputs found

    Understanding Chain Dynamics and Conformation of Conjugated Polymers in Films and Solutions

    No full text
    Significant efforts have been dedicated to the development of high-performance organic electronic materials, endowed with novel attributes that traditional inorganic silicon-based electronics cannot provide. Conjugated polymers stand out as the predominant class of organic semiconducting materials, offering a unique avenue to manufacture flexible, ductile, large-area, and customizable electronic devices through cost-effective solution processing. Despite the extensive array of processing methods, there remains a significant gap in our understanding of the dynamic and thermodynamic properties of conjugated polymer solutions and thin films. This dissertation endeavors to unravel the intricate structure-property-processing relationships of these materials by delving into their mechanical, dynamic, and thermodynamic characteristics across a spectrum of conjugated polymers. The dissertation is organized into three distinct segments. In the first segment, we probe the factors influencing stress relaxation in thin films by conducting direct stress relaxation experiments under varying conditions, such as temperature, film thickness, and the glass transition temperature of the polymers. Our findings reveal that conjugated polymers have a fast stress relaxation rate, and the polymer-air and polymer-water interfaces expedite the rate of stress relaxation in the thin glassy film. In the second segment, we delve into the chain conformation of ladder polymers, a novel class of conjugated polymers distinguished by double strains of chemical bonds along their backbones. We employ scattering techniques and other methodologies to characterize their structures. Our observations highlight that the rigid backbone of ladder polymers curtails the entropy of dissolution, consequently restricting the solubility of these unique materials. In the third segment, we investigate the impact of solvent quality on various conjugated polymers with distinct architectures. Our approach involves the use of static light scattering and other analytical techniques. We discern that the volume fraction and architecture of side chains significantly influence solution conformation. Notably, our research underscores the strong stacking propensity of conjugated polymers in solution, which can impede their solubility. In the fourth segment, we invested the impact of chain rigidity on the solution diffusion dynamics of conjugated polymer chains through a comprehensive light scattering analysis. CPs are less rigid in good solvents like chlorobenzene but more rigid in bad solvent toluene. And ladder type CPs have the most rigid backbone with stiff rod like diffusion behavior. In summary, this dissertation offers a comprehensive exploration of the mechanical, dynamic, and thermodynamic attributes of conjugated polymers, both in the context of thin films and solutions. The insights gained through this research are poised to inform the design and processing of conjugated polymers and organic electronic devices, enhancing our ability to harness their full potential

    The Impact of Differing Instability Devices on Postural Sway Parameters

    Get PDF
    Single-limb balance training is an integral part of preventing and rehabilitating lower extremity injuries. Practitioners use instability devices to provide a progressive overload to an individual during single-limb balance training sessions. Previous investigations have shown that when using instability devices, differences may or may not exist in postural sway parameters during use depending on the specific devices being assessed. Thus, this investigation sought to examine differences between a commonly used foam pad and a novel instability device (block) in measures of postural sway. This experiment consisted of 22 healthy individuals with no history of lower extremity injury and neurological disorders. Participants performed three single-limb static balance conditions on a force platform sampling at 120 Hz. Each condition contained three 20-second trials separated by thirty seconds. The mean center of pressure (CoP) values of the three trials in each condition were then compared using a within-subjects repeated measures analysis of variance. After evaluating the results, statistically significant differences were seen in sway area between conditions (f(2,42) = 5.28, p = 0.009), with the control (9.64 ± 4.53 cm) being significantly lower than both the foam pad (13.05 cm ± 4.25 cm) and block (12.33 ± 3.37 cm). Statistically significant differences were seen in CoP path length between conditions (f(2,42) = 5.52, p = 0.007), with the control (67.51 ± 9.49 cm) being significantly lower than both the foam pad (74.36 cm ± 9.76 cm) and block (76.38 ± 14.84 cm). Maximal medial-lateral CoP displacements were significantly different between conditions (f(2,42) = 6.24, p = 0.004). Lower displacements were seen in the control (1.39 ± 0.20 cm), which was statistically different from both the foam pad (1.59 ± 0.24 cm) and block (1.53 ± 0.25 cm). Maximal anterior-posterior CoP displacements were not significantly different between conditions (f(2,42) = 1.50, p = 0.23). In conclusion, this investigation provides supporting evidence that different instability devices may provide similar changes in postural sway parameters in comparison to control conditions. The novel block instability device used in this investigation may be used in a similar fashion to the traditional foam pad in both prevention and rehabilitation settings based on no differences being found between the two devices

    Camp à la Campagne: Francis Poulenc’s Les Animaux modèles

    No full text
    Francis Poulenc’s ballet Les Animaux modèles [The model animals] premiered in 1942 at the Paris Opéra during the German occupation of Paris to favorable reviews from prominent voices in the Parisian musical scene. Set in the French countryside (la campagne) in the seventeenth century, the ballet is a seemingly honest depiction of quaint rural life. To create the short vignettes that comprise the work, Poulenc (1899–1963) adapted well-known fables of the poet Jean de La Fontaine (1621–95). Existing discussions of Les Animaux modèles primarily focus on the ballet’s conception during World War II and the political implications of Poulenc’s compositional choices. The ballet also includes extremely contrasting episodes of seriousness and humor that have parallels with the queer-associated concept of camp. This paper discusses the historical development of camp criticism while noting associations between camp and French culture. Poulenc’s stylistic decisions in Les Animaux modèles are compared to camp in terms of narrative, quotation, mood, and depictions of gender. The ballet’s argument and costume images from the original production are included in appendices

    Poetry as Time Machine: Connecting Readers to the Past Through Poetry

    No full text
    Poetry has the power to enhance the delivery and learning of history. Combining the academic study of history with the lyrical language of poetry, participants will experiment with innovative ways to creatively express learning. Activities will include blackout poetry, collage poetry, persona poetry, golden shovel, and more

    Historical Specimens and Photographs Reveal Long-Term Changes In Smalltooth Sawfish (\u3ci\u3ePristis pectinata\u3c/i\u3e) Age Class Distribution and Average Size During U.S. Population Decline

    No full text
    Population-level, historical studies can provide insights on the distribution, abundance and demographic characteristics of imperiled species prior to human exploitation, habitat modification or climate change. These studies provide a baseline for contemporary data, which often shape successful management and recovery.The smalltooth sawfish (Pristis pectinata) occupies ~20% of its historical range due to declines driven primarily by mortalities in fisheries and coastal habitat loss over the last century. As a result, they are listed as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species and as Endangered federally in the United States (U.S.).Because P. pectinata grow to a large size and have a toothed rostrum, many historical photographs and specimens are archived in natural history collections. Metadata and morphometric data were collected and analysed from P. pectinata photographs (n = 84) and specimens (n = 429) to evaluate temporal changes in average size and historical distribution of five age classes in U.S. waters.Historically, smaller age classes were well-distributed throughout the northern Gulf of Mexico, while only larger age classes were recorded on the U.S. east coast, north of Florida. All age classes were found in both Florida and Texas historically, but records from Texas decline after the 1980s and remain persistent in Florida, indicative of a strong-hold for the U.S. population. Regardless of origin, individuals in three of the five age classes were larger on average historically than those observed today.Understanding which age classes used previously occupied areas will help direct habitat restoration efforts and support recovery, especially in the face of climate change. Non-traditional data sources, such as those used here, may often be the only means of providing historical context to modern research on imperiled species, ultimately guiding restoration and conservation efforts

    Capitalizing On Patrol Intelligence: Practitioner Receptivity To Patrol-Driven Intelligence-Led Policing

    No full text
    Intelligence-led policing (ILP) approaches seek to utilize a variety of strategies capitalizing on intelligence and analysis to reduce, address, and prevent crime or harm. Often, the application of these strategies involves a top-down approach. An exception to this is the Phoenix Police Department’s patrol-driven Intelligence Officer Program (IOP). This article examines the extent to which personnel from the department are receptive to this specific patrol-driven ILP approach. More specifically, responses from surveys of patrol officers, intelligence officers, and their supervisors are used to explore the perceived value of the program to patrol activities and the patrol function more broadly. Results suggest that stakeholders seem to be enthusiastic about the IOP. Importantly, it is demonstrated that more familiarity and engagement with programs can encourage greater receptivity to policing innovations such as patrol-driven ILP programs. Potential avenues for research are also discussed

    Delayed Victories: Returning the Early Homosexual Rights Movement to Campus

    No full text
    While many campuses seek to find ways to engage, support, and retain LGBTQIA+ students, there is often a lack of material in the curriculum and student-facing supports, such as libraries, multicultural centers, etc., that show the value and realities of the historical connection between academics and the pursuit of gender liberation. More historical elements, better representation, and connection could benefit all students. This chapter proposes one such history to aid that purpose: the early “Gay Liberation Movement” that saw interaction between research universities, various fields, and organizations seeking to increase opportunities and legal protections for members of the LGBTQIA+ community. By providing this history and encouraging campuses to embrace building it into their curriculum and campuses as evidence of how academia has supported the pursuit of equity, it can provide a meaningful, engaging, and significant presence to benefit all students in understanding the history of the pursuit of rights and the power of higher education

    Label-Free Characterization of Aqueous Micelle Nanostructures Via Novel Liquid In-Situ Resonant Soft X-Ray Scattering (RSoXS)

    No full text
    Micelles are fundamental to nanocarrier applications from drug delivery to environmental remediation. Their structure and dynamics are critical to their properties and functions but are challenging to measure. Here, we demonstrate a novel technique capable of such measurements based on resonant soft X-ray scattering (RSoXS). It uniquely probes organic materials using their intrinsic chemical bonds rather than laborious and disruptive labeling techniques. Our customized microfluidic cell enables RSoXS to be performed in liquid environments, allowing structure and dynamics to be measured in-situ. Using this technique in a multimodal approach, we investigated an amphiphilic polyelectrolyte copolymer micelle of three different molecular weights (Mw). Despite no measurable critical micelle concentration, structural analyses point towards multimeric structures for most Mw’s. The sizes of the micelle substructures are independent of both concentration and Mw. Combining these results with a Mw-invariant surface charge and zeta potential strengthens the link between nanoparticle size and ionic charge in solution that governs polysoap micelle structure. Such control would be critical for nanocarrier applications such as drug delivery and water remediation

    Magnolia Book Award Nominations 2025

    No full text
    https://aquila.usm.edu/magnolia_book_awards/1006/thumbnail.jp

    Examining the Effects of Food Supply on Eastern Oyster (Crassostrea virginica) Larval Performance and Settlement Potential in Delaware Bay and Mississippi Sound

    No full text
    Oyster population maintenance and growth require sufficient larval stocks capable of timely development, growth, and successful metamorphosis, whereby larval performance and settlement potential determines the capacity for a larval cohort to effectively establish into an existing population. Exogenous factors influencing larval performance include temperature, salinity, and particularly food supply. Regarding food, a sufficiently abundant and nutritionally balanced diet composed of protein, lipids, and carbohydrates is critical for successful metamorphosis. The influence of exogenous factors on Crassostrea virginica settlement potential were examined in Delaware Bay and Mississippi Sound by incorporating in situ environmental conditions and food supply metrics into a well-established biochemically-based larval performance model. Additionally, physiological variation in initial egg size, lipid content, and assimilation efficiency was modeled to reflect potential within-cohort phenotypic variability. Extended periods of suppressed salinity routinely impeded larval survival, but under adequate environmental conditions, food quality was the primary control on larval success. Reproductive seasons with favorable exogenous conditions prolonged settlement windows whereas strenuous conditions constrained settlement windows. Evaluating simulated settlement windows against concurrent recruitment observations validated the predictive power of the model and emphasized the importance of food quality on larval performance. To further characterize food assemblages available to oyster larvae in Mississippi Sound, linkages between inherent optical properties to environmental conditions and biochemical food metrics were investigated. Phytoplankton and colored detritus distributions were inferred via measured absorption coefficients but exhibited weak correspondence to biochemical metrics. Optical analyses demonstrated that biochemical food analyses remain superior food supply indicators over chlorophyll and particulate matter measurements

    8,888

    full texts

    22,106

    metadata records
    Updated in last 30 days.
    Aquila Digital Community
    Access Repository Dashboard
    Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇