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Additive Manufacturing of Piezoresistive Elastomer Nanocomposites
No full textIn the rapidly evolving landscape of the Internet of Things (IoT), the demand for flexible and wearable sensors has surged, driven by the growing need for integration into various applications ranging from physiological monitoring to smart infrastructure. Addressing this demand necessitates advancements in sensor fabrication techniques and materials that prioritize flexibility and durability yet also increase sensing capabilities.
This dissertation investigates piezoresistive elastomer polymer nanocomposites, with specific emphasis on the Direct Ink Writing (DIW) of isoprene rubber sensors. Isoprene rubber stands out as an excellent matrix choice due to its exceptional flexibility, resilience, and broad compatibility for various potential IoT applications. Additionally, its vulcanization process renders it well-suited for retrofit applications through direct adhesion to other diene rubber substrates, thus facilitating convenient conversion from non-networked products to smart technology. Moreover, additive manufacturing of piezoresistive materials enables the fabrication of unique geometries that are unattainable through traditional manufacturing methods, and consequently enhances overall sensor performance.
The investigation begins with an exploration on the influence of infill geometry and density on the piezoresistive performance of electrically conductive thermoplastic polyurethane parts fabricated via Fused Filament Fabrication offering valuable insights for optimizing sensor design with pressure loading criteria to fit specific applications.
Reinforcing fillers such as carbon black, silica, and crumb rubber are then introduced into a liquid isoprene rubber (LIR) matrix and printed via DIW. The effects of the type of filler and concentration on the rheological properties, printability, dimensional tolerance, and mechanical performance of the LIR compounds were analyzed and compared resulting in the printing of geometrically tolerant and high-strength (σu > 5 MPa) isoprene rubber parts.
Transitioning the high-strength parts to electrically conductive polymer nanocomposites was accomplished by loading the LIR matrix with conductive carbon black and multi-wall carbon nanotubes and followed by an examination of the effects of strain-rate, temperature, and cyclic loading on piezoresistive and mechanical properties. The culmination of this research yields an additively manufactured and piezoresistive isoprene rubber strain gauge possessing a gauge factor above 40 for strains greater than 70%. This novel strain gauge not only exhibits adhesion to rubber substrates that is better or comparable to commercially available adhesives but also offers the distinct advantage of enabling on-demand integration for smart products, marking a significant advancement in flexible sensor technology for the IoT landscape.Materials Science, Engineering, and Commercializatio
An Exploration of Food Security Management and Coping Strategies for Latino/a Parents Living in Central Texas During the COVID-19 Pandemic
No full textBackground: The U.S. Latino/a population is a large and fast-growing population in the country and has experienced a disproportionate burden of food insecurity compared with the non-Latino/a population. There is a need to understand how Latino/a parents use different strategies to achieve and maintain food security, particularly during stressful times such as during the COVID-19 pandemic.
Objective: To understand the food security management and coping strategies of Latino/a households through in-depth interviews.
Study Design, Settings, Participants: A cross-sectional, qualitative study with remote in-depth interviews that were conducted in Texas (October 2021-August 2022), with Latino/a parents and caregivers living in Central Texas. Trained interviewers used an interview guide (≈75 minutes/interview). Data came from a multisite study with cognitive and exploratory interviews related to food insecurity.
Measurable Outcome/ Analysis: Interviews were recorded and transcribed verbatim. Data analysis was completed through transcript review, summary sheets, coding, and peer-debriefing. A codebook was developed based on prior experience, the literature, and rounds of initial coding and discussion. The goal of analysis was to identify common patterns and develop themes and subthemes related to food security management and coping strategies.
Results: Twenty Latino/a parents and caregivers completed interviews (16 female and four male participants). Most participants were Mexican heritage and spoke primarily English. Overall, participants described similar food security management and coping strategies, despite differences in life course experiences or household characteristics. Inflation and rising food prices, the COVID-19 pandemic, and global events affected food choices and access to resources. Strategies included parents/caregivers prioritizing children's food needs over their own, rationing, reducing, and portioning out food and relying on inexpensive food staples. However, parents/caregivers described negative emotions of parental inadequacy and internalized stigma as they navigated demands for food provisioning during a stressful time.
Conclusion: Factors outside of the household exacerbated and mitigated food insecurity. Given reauthorization of important nutrition policies, this study contributes the cultural aspects of constraints and food security management practices and coping strategies of Latino/a parent and caregiver households with children. Further, it informs how Latino/a parents and caregivers manage food insecurity in the context of the challenging phenomena of the COVID-19 pandemic, subsequent inflation, as well as historical food insecurity disparities affecting the community. Knowing that crises, disasters, and different kinds of stressors will happen in the future and may happen more frequently, there is a need for an emphasis in intentionality. Indeed, intentionality in the design and expansion of policies and programs that directly support resilience in Latino/a parent and caregiver households with children. The Latino/a household food insecurity experience shares a cultural pattern of practices for food security management and coping strategies; thus, future research can explore the topic further to expand on it.
Funding: USDA This research is supported by the Food Security 25 Small Grant Program, funded through U.S. Department of Agriculture Economic Research Service in collaboration with Tufts University and University of Missouri (59-4000-0-0067, subaward #AG9033). This research is also supported by U.S. Department of Agriculture National Institute of Food and Agriculture under award number 2021-77040-34877 (Nutrition LEADers Learning Community).Family and Consumer Science
Eyes-on-trays: Developing visual literacy in sand therapists
No full textSand therapy is a highly visual therapeutic intervention modality. The client uses miniature figures, sand, and perhaps water to create a scene in the tray. As most mental health practitioners are trained in verbal-dependent therapies, how does the new sand therapist make the shift to understanding client-created scenes in the tray? This article suggests that the fields of Visual Literacy (Debes, 1968) and Visual Thinking Strategies (Housen, 1983; Yenawine, 2013) can inform sand therapy educators, trainers, and supervisors in this vital area. Eyes-on-trays, an adaptation of Housen's eyes-on-canvas, is offered as a new byword for the importance of developing visual literacy in sand therapists.Counseling, Leadership, Adult Education, and School Psycholog
Focus on miniatures: Spiritual & religious figures
No full textThis regular feature by Theresa Fraser, Associate Editor, looks at the use of spiritual and religious figures in sand therapy. With input from sand therapists from Poland and the U.S.A., she explores the use, selection and inclusion of figures, and their importance to clients.Counseling, Leadership, Adult Education, and School Psycholog
Existence of pseudosolutions for dynamic fractional differential equations
No full textIn this article, we consider the existence of pseudosolutions for boundary value problem for fractional differential equations of the formCTΔαx(t)=f(t,x(t)),for t∈Ia=[0,a]∩T,x(0)=x0,x0∈E,TCΔαx(t)=f(t,x(t)),for t∈Ia=[0,a]∩T,x(0)=x0,x0∈E,where CTΔαx(t)TCΔαx(t), α∈(0,1]α∈(0,1] denotes the Caputo fractional derivative, TT denotes a time scale, and the function ff is weakly-weakly sequentially continuous with values in a Banach space EE and satisfies some boundary conditions and conditions expressed in terms of measures of weak non-compactness.Mathematic
Asymptotic analysis of sign-changing transmission problems with rapidly oscillating interface
No full textWe study the asymptotic behavior of a sign-changing transmission problem, stated in a symmetric oscillating domain obtained by gluing together a positive and a negative material, separated by an imperfect and rapidly oscillating interface. The interface separating the two heterogeneous materials has a periodic microstructure and is a small perturbation of a flat interface. The solution of the transmission problem is continuous and its flux has a jump on the oscillating interface. Under certain conditions on the properties of the two materials, we derive the limit problem and we prove the convergence result. The T-coercivity method is used to handle the lack of coercivity for both the microscopic and the macroscopic limit problems.Mathematic
The Function of Art in Stigmata: As a Site for Memory and Community
Get PDFDuring U.S. slavery, African American communities did not have the right to ownership. Not only were they deprived of their own land or homes, but they could also not preserve the objects and heirlooms that were representative of their own lives, family, and culture. They could not be spokespeople of their own experiences in the public discourse and were not allowed to hold on to the heirlooms that represented their experiences (Miles). The few objects that they could keep, or hide, were often small personal items like combs or pieces of cloth, tools related to their work, religious items, and occasionally letters. These limited objects, when preserved and passed down, thus became charged with meaning and history but still lacked the full scope of a family’s history. Stigmata (1998) by Phyllis Alessia Perry rebels against this cultural erasure in the form of a recovery of memory and cultural identity. Perry’s novel presents a matrilineage that finds a way to preserve the identity of Ayo’s family amidst different eras of discrimination in the U.S., managing to allow ownership by the descendants of enslaved people of their own stories and culture
Supporting student success: An interview with David Arendale
Get PDFDavid Arendale, at the University of Minnesota-Twin Cities, served as an associate professor in the Department of Curriculum and Instruction within the College of Education and Human Development and manager for the Educational Opportunity Association Best Practices Clearinghouse. Arendale formerly served at the University of Missouri-Kansas City in several capacities, including senior research fellow for the Office of the Vice Chancellor of Student Affairs and Enrollment Management, national project director of Supplemental Instruction, and interim director for the Center for Academic Development. Since the mid-1980s, he has been an active member of both the College Reading and Learning Association and the National Association for Developmental Education (NADE; renamed as the National Organization for Student Success). He served as president of NADE from 1996 to 1997. In 2000, Arendale was recognized by the Council for Learning Assistance and Developmental Education Associations (CLADEA) for induction as a Founding Fellow of the profession. Arendale is devoting more time to the use of social media such as websites, YouTube channels, podcasting, and Twitter (renamed as X) to communicate in addition to publishing in print and online open-access journals. The use of the Internet, publications, presentations, and workshops communicate the best practices that others have already created. Part of this priority is reflected in his leadership of the Educational Opportunity Association National Best Practices Clearinghouse, which identifies, validates, and disseminates best practices developed by TRIO programs to increase the success of students who are low-income, first-generation college, and historically underrepresented.Developmental Educatio
Ground state solutions for fractional Kirchhoff type equations with critical growth
Get PDFWe study the nonlinear fractional Kirchhoff problem(a+b∫R3|(−Δ)s/2u|2dx)(−Δ)su+u=f(x,u)+|u|2∗s−2uin R3,(a+b∫R3|(−Δ)s/2u|2dx)(−Δ)su+u=f(x,u)+|u|2s∗−2uin R3,u∈Hs(R3),u∈Hs(R3),where a,b>0a,b>0 are constants, s(3/4,1)s(3/4,1), 2∗s=6/(3−2s)2s∗=6/(3−2s), (−Δ)s(−Δ)s is the fractional Laplacian. Under some relaxed assumptions on ff, we prove the existence of ground state solutions.Mathematic
Practical stability of stochastic differential delay equations driven by G-Brownian motion with general decay rate
No full textThis article is concerned with the quasi sure practical stability of nonlinear stochastic differential delay equations driven by G-Brownian motion (G-SDDEs) with a general decay rate. Sufficient conditions are established by constructing appropriate G-Lyapunov functionals. Moreover, we provide some numerical examples to demonstrate the effectiveness of the obtained results.Mathematic