Engineering Commons^™

Spin Disorder Control Of Topological Spin Texture, Hongrui Zhang, Yu-Tsun Shao, Xiang Chen, Binhua Zhang, Tianye Wang, Fanhao Meng, Kun Xu, Peter Meisenheimer, Xianzhe Chen, Xiaoxi Huang, Piush Behera, Sajid Husain, Tiancong Zhu, Hao Pan, Yanli Jia, Nick Settineri, Nathan Giles-Donovan, Zehao He, Andreas Scholl, Alpha N'Diaye, Padraic Shafer, Archana Raja, Changsong Xu, Lane W. Martin, Michael F. Crommie, Jie Yao, Ziqiang Qiu, Arun Majumdar, Laurent Bellaiche, David A. Muller, Robert J. Birgeneau, Ramamoorthy Ramesh

Physics Faculty Publications and Presentations

Stabilization of topological spin textures in layered magnets has the potential to drive the development of advanced low-dimensional spintronics devices. However, achieving reliable and flexible manipulation of the topological spin textures beyond skyrmion in a two-dimensional magnet system remains challenging. Here, we demonstrate the introduction of magnetic iron atoms between the van der Waals gap of a layered magnet, Fe₃GaTe₂, to modify local anisotropic magnetic interactions. Consequently, we present direct observations of the order-disorder skyrmion lattices transition. In addition, non-trivial topological solitons, such as skyrmioniums and skyrmion bags, are realized at room temperature. Our work highlights …

The National Center For Reliable Electric Power Transmission Test Facility, Anna Corbitt, Wesley G. Schwartz, Chris Farnell, Juan Carlos Balda, H. Alan Mantooth

Electrical Engineering and Computer Science Faculty Publications and Presentations

Globally, new technological solutions are being studied and developed by researchers in the field of power and energy systems. Before these solutions can be integrated into society as marketable products, thorough testing and validation of the design must be conducted. The National Center for Reliable Electric Power Transmission (NCREPT) is a unique high-power test facility located at the University of Arkansas, Fayetteville, AR, USA. NCREPT is a 12,000-square-foot laboratory space capable of testing power levels up to 6 MVA and offers testing at both the 480 V and 13.8 kV levels. NCREPT's capabilities expand outside of the scope of simply …

Fin Design Topology Optimization For Direct Liquid Cooling Of Multichip Power Modules, Aniket Ajay Ladd, Eric Roman, Yue Zhao, William P. King, Nenad Miljkovic

Electrical Engineering and Computer Science Faculty Publications and Presentations

This article demonstrates the use of topology optimization (TO) to generate optimal fin designs capable of high heat flux removal without increasing the pumping power. We use pseudo-3-D modeling validated against 3-D simulations for thermal-hydraulic performance, which reduces the computational intensity and allows for a wider range of designs to be considered. The accuracy of the pseudo-3-D modeling is aided by allowing the heat transfer coefficient to vary locally with the flow conditions, in contrast to other studies that often assume constant heat transfer coefficient independent of surface shape. We generated TO designs with density fields representing six different conventional …

The Epitaxial Growth Of Ge And Gesn Semiconductor Thin Films On C-Plane Sapphire, Emmanuel Wangila, Calbi Gunder, Petro M. Lytvyn, Mohammad Zamani-Alavijeh, Fernando Maia De Oliveira, Serhii Kryvyi, Hryhorii Stanchu, Aida Sheibani, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo

Physics Faculty Publications and Presentations

Ge_1−xSn_x growth on a new sapphire platform has been demonstrated. This involved the growth of GeSn on Ge/GaAs layers using the algorithm developed. The resultant growths of Ge on GaAs/AlAs/sapphire and Ge_1−xSn_x on Ge/GaAs/AlAs/sapphire were investigated by in situ and ex situ characterization techniques to ascertain the surface morphology, crystal structure, and quality. The growth mode of Ge on GaAs was predominantly two-dimensional (2D), which signifies a layer-by-layer deposition, contributing to enhanced crystal quality in the Ge/GaAs system. The growth of Ge_1−xSn_x with 10% Sn on a graded profile for 30 …

Algorithm-Based Linearly Graded Compositions Of Gesn On Gaas (001) Via Molecular Beam Epitaxy, Calbi Gunder, Mohammad Zamani-Alavijeh, Emmanuel Wangila, Fernando Maia De Oliveira, Aida Sheibani, Serhii Kryvyi, Paul C. Attwood, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo

Physics Faculty Publications and Presentations

The growth of high-composition GeSn films in the future will likely be guided by algorithms. In this study, we show how a logarithmic-based algorithm can be used to obtain high-quality GeSn compositions up to 16% on GaAs (001) substrates via molecular beam epitaxy. Herein, we use composition targeting and logarithmic Sn cell temperature control to achieve linearly graded pseudomorph Ge_1−xSn_x compositions up to 10% before partial relaxation of the structure and a continued gradient up to 16% GeSn. In this report, we use X-ray diffraction, simulation, secondary ion mass spectrometry, and atomic force microscopy to analyze and …

Revealing The Three-Dimensional Arrangement Of Polar Topology In Nanoparticles, Chaewa Jeong, Juhyeok Lee, Hyesung Jo, Jaewhan Oh, Hionsuck Baik, Kyoung-June Go, Junwoo Son, Si-Young Choi, Sergey Prosandeev, Laurent Bellaiche, Yongsoo Yang

Physics Faculty Publications and Presentations

In the early 2000s, low dimensional ferroelectric systems were predicted to have topologically nontrivial polar structures, such as vortices or skyrmions, depending on mechanical or electrical boundary conditions. A few variants of these structures have been experimentally observed in thin film model systems, where they are engineered by balancing electrostatic charge and elastic distortion energies. However, the measurement and classification of topological textures for general ferroelectric nanostructures have remained elusive, as it requires mapping the local polarization at the atomic scale in three dimensions. Here we unveil topological polar structures in ferroelectric BaTiO₃ nanoparticles via atomic electron tomography, which …

Yeast Surface Display Of Multiple Heterologous Proteins Via Molecular And Biochemical Processing Techniques, Shadrach Ibinola

Graduate Theses and Dissertations

The arming of yeast cell wall, also known as yeast surface display, is an effective technology for expressing target proteins extracellularly. It has been shown to provide bioengineered yeast with qualities that are not known to native yeast such as the ability to survive harsh conditions including high pH and temperature, for example. Furthermore, this technique has been implemented for various applications which include, protein engineering, bioethanol production, bioremediation, vaccine construction, and antibody development. The major mechanisms of yeast surface display exploit agglutination, flocculation, or proteins with internal repeats as the means by which a target (protein) is covalently attached …

Developing Anisotropic Soft Matter As Functional Materials To Interface With Biological Systems, Homa Ghaiedi

Graduate Theses and Dissertations

Liquid crystals (LCs) constitute a subset of soft matter possessing hybrid characteristics from both liquid and crystalline phases. In this state, the center of masses remains uncorrelated similar to an isotropic phase, while the long axis of molecules aligns in parallel, resulting in molecules exhibiting orientational and positional order, either individually or concurrently. The directional alignment inherent in LCs arises from the asymmetrical shape and structure of the constituent molecules, causing a spontaneous self-assembly into ordered phases. This cooperative molecular behavior manifests distinctive optical features when subjected to cross polarizers. The remarkable sensitivity of LCs to external stimuli, including temperature, …

Quantification Of Age-Related Changes In The Structure And Mechanical Function Of Skin With Multiscale Imaging, Alan E. Woessner, Nathan J. Witt, Jake D. Jones, Edward A. Sander, Kyle P. Quinn

Biomedical Engineering Faculty Publications and Presentations

The mechanical properties of skin change during aging but the relationships between structure and mechanical function remain poorly understood. Previous work has shown that young skin exhibits a substantial decrease in tissue volume, a large macro-scale Poisson’s ratio, and an increase in micro-scale collagen fiber alignment during mechanical stretch. In this study, label-free multiphoton microscopy was used to quantify how the microstructure and fiber kinematics of aged mouse skin affect its mechanical function. In an unloaded state, aged skin was found to have less collagen alignment and more non-enzymatic collagen fiber crosslinks. Skin samples were then loaded in uniaxial tension …

Memo: Dataset And Methods For Robust Multimodal Retinal Image Registration With Large Or Small Vessel Density Differences, Chiao-Yi Wang, Faranguisse Kahki Sadrieh, Yi-Ting Shen, Shih-En Chen, Sarah Kim, Victoria Chen, Achyut Raghavendra, Dongyi Wang, Osamah Saeedi, Yang Tao

Biological and Agricultural Engineering Faculty Publications and Presentations

The measurement of retinal blood flow (RBF) in capillaries can provide a powerful biomarker for the early diagnosis and treatment of ocular diseases. However, no single modality can determine capillary flowrates with high precision. Combining erythrocyte-mediated angiography (EMA) with optical coherence tomography angiography (OCTA) has the potential to achieve this goal, as EMA can measure the absolute RBF of retinal microvasculature and OCTA can provide the structural images of capillaries. However, multimodal retinal image registration between these two modalities remains largely unexplored. To fill this gap, we establish MEMO, the first public multimodal EMA and OCTA retinal image dataset. …

Ssnet: Exploiting Spatial Information For Tobacco Stem Impurity Detection With Hyperspectral Imaging, Chao Zhou, Zhenye Li, Dongyi Wang, Sheng Xue, Tingting Zhu, Chao Ni

Biological and Agricultural Engineering Faculty Publications and Presentations

Tobacco stems are a critical component in cigarette production in China. However, accurately and promptly identifying impurities in tobacco stems remains a challenge with current deep learning methods, often failing to meet industry standards. This study introduces the Spectral-Spatial Network (SSNet), which is specifically optimized for rapid and precise detection of impurities in tobacco stems, leveraging spatial information in hyperspectral imaging. Designed to align with the high-speed requirements of industrial processing, SSNet effectively overcomes the complexities associated with analyzing hyperspectral data. The integration of spatial information particularly enhances recognition accuracy, especially in areas affected by fringe patterns. Our experiments reveal …

Modeling, Characterization, And Machine Learning Algorithm For Rectangular Choke Horn Antennas, Ibrahim N. Alquaydheb, Saleh A. Alfawaz, Amirreza Ghadimi Avval, Sara Ghayouraneh, Samir M. El-Ghazaly

Electrical Engineering and Computer Science Faculty Publications and Presentations

In this work, we present the design and modeling of a new type of choke horn antenna. It incorporates a rectangular waveguide and a rectangular choke acting as a parasitic element. The four-sided geometry of the antenna is applicable to systems that utilize rectangular waveguides. Also, it can overcome the need for rectangular-to-circular transition of transmission line or mode conversion. The main objective of this paper is to develop a model that calculates the far field radiation characteristics of the proposed antenna (analytical part) and to incorporate a finite element method (FEM) solver that adds to the theoretical solution (empirical …

Immersive Virtual Reality-Based Learning As A Supplement For Biomedical Engineering Labs: Challenges Faced And Lessons Learned, Ishita Tandon, Vitali Maldonado, Megan Wilkerson, Amanda Walls, Raj R. Rao, Mostafa Elsaadany

Biomedical Engineering Faculty Publications and Presentations

Introduction: Immersive virtual reality (VR) based laboratory demonstrations have been gaining traction in STEM education as they can provide virtual hands-on experience. VR can also facilitate experiential and visual learning and enhanced retention. However, several optimizations of the implementation, in-depth analyses of advantages and trade-offs of the technology, and assessment of receptivity of modern techniques in STEM education are required to ensure better utilization of VR-based labs.

Methods: In this study, we developed VR-based demonstrations for a biomolecular engineering laboratory and assessed their effectiveness using surveys containing free responses and 5-point Likert scale-based questions. Insta360 Pro2 camera and Meta Quest …

Electrical And Thermal Characterization Of (250 °C) Sic Power Module Integrated With Ltcc-Based Isolated Gate Driver, Salahaldein Ali Aboajila Ahmed, Pengyu Lai, Sudharsan Chinnaiyan, H. Alan Mantooth, Zhong Chen

Electrical Engineering Faculty Publications and Presentations

The high-voltage SiC MOSFET power modules enable high-frequency and high-efficiency power conversion. The parasitic inductances induced by traditional packages of this device technology significantly deteriorate device switching performance, especially in high-temperature applications. In this paper, a novel low-cost discrete SMD component gate driver embedded in a SiC MOSFET power module is introduced. A newly integrated packaging structure has been introduced and proved to be efficient in reducing package-related turn-on loss and turn-off parasitic ringing. However, the gate propagation delay and optocoupler on-chip weak output signal in such a structure become limitations for further pushing the operating frequency and the output …

Quantifying Wildfire Drivers And Predictability In Boreal Peatlands Using A Two-Step Error-Correcting Machine Learning Framework In Tefire V1.0, Rongyun Tang, Mingzhou Jin, Daniel M. Ricciuto, Anping Chen, Yulong Zhang

Biological and Agricultural Engineering Faculty Publications and Presentations

Wildfires are becoming an increasing challenge to the sustainability of boreal peatland (BP) ecosystems and can alter the stability of boreal carbon storage. However, predicting the occurrence of rare and extreme BP fires proves to be challenging, and gaining a quantitative understanding of the factors, both natural and anthropogenic, inducing BP fires remains elusive. Here, we quantified the predictability of BP fires and their primary controlling factors from 1997 to 2015 using a two-step correcting machine learning (ML) framework that combines multiple ML classifiers, regression models, and an error-correcting technique. We found that (1) the adopted oversampling algorithm effectively addressed …

Computational Discovery Of Microstructured Composites With Optimal Stiffness-Toughness Trade-Offs, Beichen Li, Bolei Deng, Wan Shou, Tae-Hyun Oh, Yuanming Hu, Yiyue Luo, Liang Shi, Wojciech Matusik

Mechanical Engineering Faculty Publications and Presentations

The conflict between stiffness and toughness is a fundamental problem in engineering materials design. However, the systematic discovery of microstructured composites with optimal stiffness-toughness trade-offs has never been demonstrated, hindered by the discrepancies between simulation and reality and the lack of data-efficient exploration of the entire Pareto front. We introduce a generalizable pipeline that integrates physical experiments, numerical simulations, and artificial neural networks to address both challenges. Without any prescribed expert knowledge of material design, our approach implements a nested-loop proposal-validation workflow to bridge the simulation-to-reality gap and find microstructured composites that are stiff and tough with high sample efficiency. …

Vaccine Immunogenicity Versus Gastrointestinal Microbiome Status: Implications For Poultry Production, Chrysta N. Beck, Jiangchao Zhao, Gisela F. Erf

Poultry Science Faculty Publications and Presentations

At the turn of the 21st century, the importance of maintaining a balanced microbiome was brought to the forefront of the microbiology, immunology, and physiology research fields. Exploring the complex interactions between vaccine administration, mucosal microbiome, oral tolerance, and enteric inflammation in health and disease is challenging since environmental factors (such as diet and sanitation) have major influences on gut microbiota composition. High enteric pathogen load has been shown to contribute to dampened cell-mediated and humoral immune responses to vaccines in human case studies, either through elevated enteric inflammation or increased tolerance to environmental microbes. Although antibiotic and probiotic interventions …

Us Public Opinion About The Safety Of Gene Editing In The Agriculture And Medical Fields And The Amount Of Evidence Needed To Improve Opinions, Brandon R. Mcfadden, Joy N. Rumble, Kathryn A. Stofer, Kevin M. Folta

Agricultural Economics and Agribusiness Faculty Publications and Presentations

Introduction: Implementation of gene editing in agriculture and medicine hinges on public acceptance. The objectives of this study were to explore U.S. public opinion about gene editing in agricultural and medical fields and to provide more insight into the relationship between opinions about the safety of gene editing and the potential impact of evidence to improve opinions about safety.

Methods: Data were from two samples of U.S. respondents: 1,442 respondents in 2021 and 3,125 respondents in 2022. Survey respondents provided their opinions about the safety of gene editing in the agricultural and medical fields and answered questions about the number …

Accelerating Neurotechnology Development Using An Agile Methodology, Anil Kumar Thota, Ranu Jung

Biomedical Engineering Faculty Publications and Presentations

Novel bioelectronic medical devices that target neural control of visceral organs (e.g., liver, gut, spleen) or inflammatory reflex pathways are innovative class III medical devices like implantable cardiac pacemakers that are lifesaving and life-sustaining medical devices. Bringing innovative neurotechnologies early into the market and the hands of treatment providers would benefit a large population of patients inflicted with autonomic and chronic immune disorders. Medical device manufacturers and software developers widely use the Waterfall methodology to implement design controls through verification and validation. In the Waterfall methodology, after identifying user needs, a functional unit is fabricated following the verification loop (design, …

The Aim To Decentralize Economic Systems With Blockchains And Crypto, Mary Lacity

Arkansas Law Review

As an information systems (“IS”) professor, I wrote this Article for legal professionals new to blockchains and crypto. This target audience likely is most interested in crypto for its legal implications—depending on whether it functions as currencies, securities, commodities, or properties; however, legal professionals also need to understand crypto’s origin, how transactions work, and how they are governed.

Grand Challenges In Membrane Transport, Modeling And Simulation, Jacob Monroe, Chidambaram Thamariselvan, Ranil Wickramasinghe

Chemical Engineering Faculty Publications and Presentations

Today, membranes play an increasing role in separation processes across a wide range of industries, including water treatment, biomedical applications, bioseparations, and gas separations (Yeom et al., 2022). Numerous different membrane types exist, which can be broadly categorized as either porous or non-porous, where pores may be or may not be filled with a separate phase from the bulk solvent and membrane phases. In addition, various driving forces exist - pressure, concentration, electric field, etc.—that lead to transport across the membrane. For a porous membrane, solute transport is usually governed by convective flow through the pores. Micron-sized pores are used …

Table Of Contents, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

Academy Presidents And Institutional Members, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

Business Meeting Report (Secretary's And Treasurer's Report), Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

Probable Extirpation Of The Jackrabbit (Lepus Californicus) From Arkansas, D.B. Sasse

Journal of the Arkansas Academy of Science

The black-tailed jackrabbit (Lepus californicus) was first documented in Arkansas during the modern era in Franklin County in 1927. Over the next few decades records were reported from multiple counties in northwest Arkansas and the species was locally common in Benton, Crawford, and Washington counties in the 1950s. The last Arkansas record documented in the scientific literature was from 1968 and since then there have only been three credible reports, with the last being from the late 1980s. The Arkansas Game and Fish Commission solicited reports of jackrabbits from the public and failed to find evidence of them from a …

A Review Of Herpetofaunal Distributions In Arkansas With Special Emphasis On Contributions From Citizen Science: Part I – Snakes, R. Jacobs, N. Ortiz, J. Jackson, J.D. Willson, K.G. Roberts, R. Kannan

Journal of the Arkansas Academy of Science

We present a comprehensive updated review of the distributions of the 38 species of snakes in Arkansas. We compare historical and current distributions with citizen science data uploaded and verified in iNaturalist, a leading biodiversity monitoring online citizen science database. The Arkansas Herpetological Atlas, a website maintaining species occurrence records, is also used and compared. We highlight the role played by iNaturalist in enhancing our knowledge of snake distributions in Arkansas. 10,885 verified and vetted Research Grade (RG) observations of Arkansas snakes have been recorded in iNaturalist, expanding the known distributions of 36 of the 38 species. This is the …

Ultrastructure Of The Biflagellated Spermatozoon In The Western Siren, Siren Nettingi (Caudata: Sirenidae), Using Scanning Electron Microscopy, S.E. Trauth

Journal of the Arkansas Academy of Science

I investigated the ultrastructure of the biflagellated spermatozoon of the Western Siren, Siren nettingi, using scanning electron microscopy from salamanders collected in northeastern Arkansas. My primary goal in this study was to reveal the general morphology of the distinctive sperm cell components (two axonemes, two undulating membranes, and two axial fibers), which run nearly the entire length of the spermatozoon. These remarkable gamete structures are found in members of the salamander family Sirenidae and do not conform to spermatozoal ultrastructure of any other salamander species. Moreover, the biflagellated sperm are the end product of an extraordinary assemblage of complex maturation …

Journal Of The Arkansas Academy Of Science Volume 78, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

History And Distribution Of The Wood Stork (Mycteria Americana) In Arkansas, R. Tumlison, L. Serviss

Journal of the Arkansas Academy of Science

Wood Storks (Mycteria americana) were thought to be common visitors to Arkansas in the early 1900s, but observations declined mid-century. Surveys of citizen science data and other online sources indicate that numbers of unique observations and total counts of birds have increased since 2000. Storks do not breed here, but have been reported in 34 of 75 counties, and appear mostly in August and September. Birds apparently originate from Mexico. Number of observations have increased since 2016, but many of those observations include only a few birds rather than larger flocks.

Geographical Variation In Songs Of Bachman’S Sparrow (Peucaea Aestivalis), L. Nguyen, K. Doñas, J. Jackson, R. Kannan

Journal of the Arkansas Academy of Science

We present an analysis of geographic variation in primary song components of the Near Threatened North American endemic, Bachman’s Sparrow (Peucaea aestivalis). These songs have 2 distinct portions: an introductory tweet we call the "whistle" and a more complex second portion that we call the "trill". We analyzed 327 songs from 111 recordings downloaded from eBird.org from the entire current range of the species. We grouped the recordings into 3 distinct geographic clusters, East, Central, and West. The data measured from spectrograms suggest a significant statistical difference among groups for 3 measured characteristics: frequency range of trill, number of horizontal …