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Exploring topological defects in Janus bilayers of Cr(I,Cl)\u3csub\u3e3\u3c/sub\u3e and Cr(I,Br)\u3csub\u3e3\u3c/sub\u3e
Get PDFChromium halides such as CrI3 have attracted interest recently. They possess the remarkable property of sustaining long-range magnetic order down to the thickness of only a few layers [1, 2]. However, CrI3 lacks Dzyaloshinskyii– Moriya interaction (DMI) due to inversion center present between the adjacently bonded Chromium atoms.
The inversion center can be removed through the fabrication of Janus Monolayers by adding another trihalide along with Iodine to synthesize the material, that is to grow Janus monolayers Cr(I, X)3 where X is another halide such as Cl or Br [3].
Previous work has predicted non-trivial spin textures such as out-of-plane Néel-type cycloid with metastable Domain-Wall Skyrmions (DWS) in Cr(I,Br)3 or stabilization of bimerons in Cr(I,Cl)3 monolayers [3].
However, magnetic properties of these Janus bilayers have yet to be explored.https://scholarworks.uark.edu/hnrcsturpc25/1032/thumbnail.jp
Development of Soil Water Characteristic Curves through Control of Relative Humidity
No full textThe relationship between soil suction and soil water content in unsaturated soil mechanics is important but can be difficult to measure. The objective of the research described herein was to develop soil water characteristic curves (SWCC) from relative humidity values by incorporating the use of glycerin-water mixtures. Glycerin-water mixtures can be used to achieve different relative humidity levels by varying the concentration of glycerin within the mixture. The relative humidity created by each mixture was measured with a relative humidity sensor, and the relative humidity values and Kelvin’s equation were used to compute the total suction.
Soil water characteristic curves were then developed using the relationship between the applied total suction and the measured gravimetric water content of a 15-bar high air entry stone and four soils, including: illite, red clay, kaolinite, and Donna Fill. The soil SWCCs, obtained using glycerin-water mixtures, were compared with the SWCC developed using a chilled mirror hygrometer and the filter paper method. For all soils, the water-glycerin method effectively developed the portion of the SWCC at low water content and high suction values. For the soils that behaved as cohesive materials, there was sufficient data to establish the SWCC using the relative humidity method for suction values greater than 1000 kPa. At lower suction values, there was a lack of suction data. For the soil that behaved as a cohesionless materials, the relative humidity method resulted in all data residing along the residual water content, making the development of the SWCC difficult. Based on the results, the inexpensive and simple relative humidity method may be used to develop SWCC for cohesive soils at low water contents and high suction values
Analysis of the Mechanical, Microstructural, and Biocompatibility Properties of Novel Magnesium-based Hybrid Nanocomposite Materials for Orthopedic Applications
No full textBone fractures and complete joint replacements are becoming more common, primarily because of accidents and age-related issues. Conventional solutions to treat these orthopedic injuries involve inert metal alloys to correct bone fractures until the healing process is complete, where a secondary revision surgery is then required to remove the implant. Issues regularly associated with these solutions include stress shielding, bone resorption, infection, inflammation, and implant loosening. Magnesium (Mg)-based nanocomposites offer promising potential as an alternative to commonly used metal alloys because of their favorable mechanical properties and biocompatibility. A particularly advantageous property of Mg is its natural biodegradation in vivo, meaning the implant will dissolve once healing has been completed, eliminating the need for revision surgeries. However, Mg’s naturally high corrosion rate presents significant challenges for these applications, including compromised mechanical stability and biocompatibility. This research investigates the effects of boron nitride (BN) and silicon carbide (SiC) nanoparticle reinforcement on the degradation behavior, mechanical strength, microstructural properties, and biocompatibility of Mg-based nanocomposites. The influence of adding each nanoparticle individually showed a significantly positive effect on mechanical and corrosion properties in current literature. However, further investigation into the effect of adding these two nanoparticles together into the magnesium matrix has yet to be conducted. Therefore, this study investigates the influence of adding these two nanoparticles in equal volume percentages to create hybrid Mg-based nanocomposites to more comprehensively assess their combined influence on mechanical properties, corrosion resistance, and biocompatibility. Characterization techniques included porosity measurements, Vickers microhardness testing, contact angle analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), and X-ray diffraction (XRD) analysis. Biocompatibility was assessed through cell viability assays and a PFA cell fixation study, while corrosion performance was evaluated via SEM imaging, electrochemical corrosion tests, and immersion testing in complete αMEM, followed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The Zk60-0.5%BN-0.5%SiC nanocomposite exhibited improved hardness, refined grain structure, and strong interparticle bonding with minimal porosity. SEM and EDX analyses confirmed uniform nanoparticle dispersion and grain boundary reinforcement. However, the same composite also showed increased corrosion susceptibility, as indicated by higher pH shifts, greater Mg ion release, and more pronounced Mg(OH)₂ surface deposits during SEM characterization. Biocompatibility assays revealed moderate cytotoxicity in both the Pure Zk60 and Zk60-0.5%BN-0.5%SiC groups, with reduced cell adhesion linked to elevated corrosion rates in the latter. Despite these challenges, the mechanical benefits and early-stage cell attachment suggest strong potential for orthopedic use. Future work should focus on optimizing nanoparticle volume fractions and applying corrosion-resistant coatings to enhance the long-term viability of Mg-based nanocomposites in clinical settings. Overall, the Mg nanocomposites reinforced with BN and SiC nanoparticles demonstrated enhanced mechanical and microstructural properties suitable for orthopedic implants, but the increased corrosion rate needs to be addressed before clinical applications
An Analysis of the Effectiveness of Informational Interviews on Biomedical Engineering Students\u27 Professional Growth, Career Preparedness, and Networking Skills Development
No full textBone fractures and complete joint replacements are becoming more common, primarily because of accidents and age-related issues. Conventional solutions to treat these orthopedic injuries involve inert metal alloys to correct bone fractures until the healing process is complete, where a secondary revision surgery is then required to remove the implant. Issues regularly associated with these solutions include stress shielding, bone resorption, infection, inflammation, and implant loosening. Magnesium (Mg)-based nanocomposites offer promising potential as an alternative to commonly used metal alloys because of their favorable mechanical properties and biocompatibility. A particularly advantageous property of Mg is its natural biodegradation in vivo, meaning the implant will dissolve once healing has been completed, eliminating the need for revision surgeries. However, Mg’s naturally high corrosion rate presents significant challenges for these applications, including compromised mechanical stability and biocompatibility. This research investigates the effects of boron nitride (BN) and silicon carbide (SiC) nanoparticle reinforcement on the degradation behavior, mechanical strength, microstructural properties, and biocompatibility of Mg-based nanocomposites. The influence of adding each nanoparticle individually showed a significantly positive effect on mechanical and corrosion properties in current literature. However, further investigation into the effect of adding these two nanoparticles together into the magnesium matrix has yet to be conducted. Therefore, this study investigates the influence of adding these two nanoparticles in equal volume percentages to create hybrid Mg-based nanocomposites to more comprehensively assess their combined influence on mechanical properties, corrosion resistance, and biocompatibility. Characterization techniques included porosity measurements, Vickers microhardness testing, contact angle analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), and X-ray diffraction (XRD) analysis. Biocompatibility was assessed through cell viability assays and a PFA cell fixation study, while corrosion performance was evaluated via SEM imaging, electrochemical corrosion tests, and immersion testing in complete αMEM, followed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The Zk60-0.5%BN-0.5%SiC nanocomposite exhibited improved hardness, refined grain structure, and strong interparticle bonding with minimal porosity. SEM and EDX analyses confirmed uniform nanoparticle dispersion and grain boundary reinforcement. However, the same composite also showed increased corrosion susceptibility, as indicated by higher pH shifts, greater Mg ion release, and more pronounced Mg(OH)₂ surface deposits during SEM characterization. Biocompatibility assays revealed moderate cytotoxicity in both the Pure Zk60 and Zk60-0.5%BN-0.5%SiC groups, with reduced cell adhesion linked to elevated corrosion rates in the latter. Despite these challenges, the mechanical benefits and early-stage cell attachment suggest strong potential for orthopedic use. Future work should focus on optimizing nanoparticle volume fractions and applying corrosion-resistant coatings to enhance the long-term viability of Mg-based nanocomposites in clinical settings. Overall, the Mg nanocomposites reinforced with BN and SiC nanoparticles demonstrated enhanced mechanical and microstructural properties suitable for orthopedic implants, but the increased corrosion rate needs to be addressed before clinical applications.https://scholarworks.uark.edu/hnrcsturpc25/1050/thumbnail.jp
Surviving Their Stripes: Quality of Life and Coping for Individuals with Ehlers-Danlos Syndrome
No full textHypermobile type Ehlers-Danlos Syndrome (hEDS) is a subtype of Ehlers-Danlos Syndrome, a genetic connective tissue disorder with complexities involving joint hypermobility, tissue fragility and severe pain. Patients with hEDS often experience misdiagnosis, medical dismissal and years of waiting for a diagnosis. This study aims to evaluate the quality of life and diagnostic journey for patients living with hEDS. Qualitative, cross-sectional and semi-structured interviews were conducted in this study using a descriptive, phenomenological methodological approach. The specific phenomenon is the experience of the hEDS diagnosis and how that diagnosis further impacts patient life. The two primary research questions that we aimed to answer in this study include 1) What is the lived experience of someone being diagnosed with hEDS in the United States? 2) What impact did this diagnosis have on their life? Descriptive phenomenology examines the individual\u27s experiences, behaviors and motivations. hEDS patients were the target population of this study. Patients were recruited via volunteer sampling through social media. Seventeen women with hEDS were screened and required to complete a demographic survey following informed consent. The selected interview questions aimed to learn more about each individual\u27s journey before, during and after diagnosis. The transcribed interviews were observed with thematic analysis which included separating the stated information into several codes which encompassed the diagnostic odyssey. After thoroughly coding all interviews, six themes were identified: 1) The journey to hEDS can be long, complicated and frustrating, a proper diagnosis can be reliving and validating, self-advocacy is crucial, coping with hEDS requires many tools in the toolbox, doctors can make or break the hEDS experience for patients and hEDS impacts mental health just as much as physical health. This study has highlighted important issues that patients with hEDS commonly experience while living with hEDS and validates the difficulty that comes along with an hEDS diagnosis. From this study, we can recognize the importance of advocacy and coping skills in order to medically and mentally manage an hEDS diagnosis. We also see a necessity for medical providers to be properly educated of the manifestations of hEDS in order to reduce the diagnostic timeline and medical gaslighting that the patient experiences
A Battle Among Sovereigns: Partnering Federal Exhaustion and Infringement Principles to Safeguard Tribal Court Jurisdiction Over Labor and Employment Disputes
Get PDFSince the shift in federal policy starting in the late 1960s towards Indian self-determination and self-government, Indian tribes have leveraged federal support to enter into a broad variety of commercial activities to fund their governments and community programs. Despite some of the earliest iterations of the policy of self-determination being a call to “break decisively with the past and to create the conditions for a new era in which the Indian future is determined by Indian acts and Indian decisions” and to uphold promises to provide tribes with “a standard of living comparable to that of other Americans,” tribes have been threatened with assaults on their authority to govern the employment relations within their enterprises. While recent debate has centered around the National Labor Relations Board (NLRB) overturning its long-held position that the National Labor Relations Act (NLRA) did not apply to tribal businesses because they were governmental entities, there had already been a circuit split regarding whether other federal labor and employment laws of general applicability applied to tribal enterprises. This article seeks to resolve this circuit split through the revamping of current legal frameworks within this area of the law. In Part II, I will discuss how tribal sovereignty has developed as a legal concept, as well as current and potential barriers to federal infringement on this sovereignty, such as sovereign immunity, the federal exhaustion doctrine, and the federal infringement doctrine. Part III will address the circuit split in more depth and discuss problems with some courts’ flawed reasoning. Part IV will propose that the federal exhaustion doctrine should be more stringently enforced before federal jurisdiction can be maintained, and that the federal infringement doctrine should underlie the jurisdictional part of the exhaustion doctrine analysis. Lastly, Part V will briefly conclude the paper with some closing remarks
The Learning Crisis in the United States Three Years After COVID-19
Get PDFThe COVID-19 pandemic caused widespread disruptions to education, with school closures affecting over one billion children. These closures, aimed at reducing virus transmission, resulted in significant learning losses, particularly in mathematics and science. Using United States data from TIMSS, this study analyzes the impact of school closure on learning outcomes. The losses amount to 0.36 SD for mathematics and 0.16 SD for science. The declines are similar across grades. The average decline in mathematics performance among U.S. students is substantially greater than the global average. n science, the decline observed among U.S. students does not significantly differ from the global trend. Girls experienced greater deviations from long-term trends than boys across both subjects and grade levels, reversing long term trends that once favored girls. Robustness checks confirm that pandemic-related school closures caused the decline in mathematics, while the downturn in science had already begun before COVID-19
Quantifying Freshwater Salinization Impacts on Nitrate Removal via Denitrification in Urban Streams
Get PDFAs the urban world expands, the construction of impervious surfaces increases erosion and runoff into nearby streams. Urbanization also adds waste from human activity into the environment. One of these wastes is runoff from road salt application in winter months, which can increase stream salinization and interfere with other important ecological processes, such as denitrification. Therefore, the objective of this study was to compare nitrate removal via denitrification between two urban streams to understand the role of road salts in freshwater salinization. We compared conductivity measurements between the streams to see how background conductivity (a proxy for salinity) influences resilience of denitrification to salinization. We also compared how typical road salts and road salts with beet juice (an “eco-friendly” alternative) have different effects on denitrification, to understand the impacts of road salts in urban streams. In addition, we collected samples and ran analyses in winter and summer to understand if seasonal salt holdover impacts denitrification rates. We nitrogen transformation rates were significantly different between the two streams with different background conductivities (p0.1). Our work sheds light on the potential road salt impacts on important ecological processes, as well as assessing if “eco-friendly” alternatives have unexpected impacts on ecosystem functions. These data and results can inform road salt usage, as well as protection and conservation efforts towards urban streams
Pediatric Occupational Therapists’ Perception on How Nature-Based Play Affects Fine Motor Development
Get PDFThis study aimed to explore the benefits of nature-based pediatric occupational therapy and the influence of nature and nature-based play on fine motor development. It was hypothesized that nature and nature-based play would positively impact a child’s fine motor skills, and that nature-based occupational therapy would offer unique benefits to a child’s therapeutic experience. To examine these relationships, a survey was distributed to pediatric occupational therapists across the United States. The survey was designed to gather insights into how occupational therapy supports fine motor development, how nature-based play/therapy enhances these skills, and the perceived benefits of incorporating nature into therapeutic practices. This study found a profound influence of nature-based therapy (NBT) on various aspects of child development. Pediatric occupational therapists (OTs) note NBT’s positive effects on a child’s fine motor skills as well as their physical, social, cognitive, and emotional development. It was also found that there is a lack of clarity surrounding NBT within the OT field, which may contribute to misunderstandings about its purpose and application