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2020 IEEE Nuclear science Symposium and Medical Imaging Conference, NSS/MIC 2020

作者： Woldegiorgis, Surafel Nimmagadda, Jyothier Baciak, James The Nuclear Engineering Program The Department of Materials Science and Engineering The University of Florida GainesvilleFL32603 United States

ISBN: (纸本)9781728176932

The energy spectrum and spatial distribution of the neutron beam from a reactor is an essential component of designing experimentations utilizing the reactor as a radiation source. Obtaining such information requires the use of detailed MCNP model of the reactor and experimental validation procedures. After updating the MCNP model of the University of Florida Training Reactor (UFTR) to align it with the current core arrangement that uses low enriched uranium (LEU), both the radial neutron flux toward the beam ports and the energy spectrum at the reactor core were generated using the model. This was followed by experimental validations based on neutron activation analysis (NAA) by irradiating multiple activation foils. A constant ratio between MCNP and measured neutron flux values was obtained at multiple locations along the reactor's beam ports, showing that the model captures the spatial distribution of neutron flux profiles without a significant systematic error. The energy spectrum at the core was extracted using the Unfolding with MAXED and GRAVEL (UMG) software. The spectrum unfolded by both MAXED and GRAVEL algorithms display features expected in thermal reactor neutron energy distribution, i.e., thermal, fast or fission, and intermediate or slowing down regions. The thermal and epithermal neutron fluxes at the reactor core calculated from the spectrum unfolded by the MAXED n algorithm are 1. 56 ± 0. 12 × 1012 cm2s and 1. 98 ± 0. 01 × 1012 n sm2s, whereas the corresponding values calculated from the spectrum unfolded by the GRAVEL algorithm are 1. 50 ± 0. 12 × n 1012 n and 3. 74 ± 0. 21 × 1012. Following the cm2s cm2s experimental validation, the full geometry MCNP model of the reactor has been utilized for a neutron tomography research project and it will continue to benefit future projects using the reactor facility. © 2020 IEEE

关键词： Neutron flux

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A Soft Robotic Wrist Orthosis Using Textile Pneumatic Actuators For Passive Rehabilitation

A Soft Robotic Wrist Orthosis Using Textile Pneumatic Actuat...

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IEEE International Conference on Soft Robotics (RoboSoft)

作者： Anoush Sepehri Samuel Ward Michael T. Tolley Tania K. Morimoto The Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla CA USA The Departments of Orthopaedic Surgery and the Department of Radiology University of California San Diego La Jolla CA USA The Department of Mechanical and Aerospace Engineering and the Materials Science and Engineering Program University of California San Diego. La Jolla CA USA The Department of Mechanical and Aerospace Engineering and the Department of Surgery University of California San Diego La Jolla CA USA

Wearable soft robots can be effective tools for rehabilitation due to their inherent safety and compliance. Challenges, however, exist regarding the development of suitable on-body actuation methods. Furthermore, the majority of existing soft wearable devices are not accessible and easy to use for those with physical disabilities. This paper presents the design, fabrication, and characterization of a soft robotic wrist orthosis to achieve flexion and extension for continuous passive motion therapy. First, we developed bending textile pneumatic actuators that could be mechanically programmed to conform to the target joint's anatomy when mounted on the body. The textile pneumatic actuators achieved up to 2.24 Nm of torque at 124 kP $a$ . We then embedded the textile pneumatic actuators into a soft wrist orthosis that we designed to ensure it was easy to don/doff without assistance. To determine the operating pressures and range of motion achievable by our soft robotic wrist orthosis, we conducted a device evaluation study with three healthy individuals. Our device achieved over 100 degrees of flexion/extension assistance at operating pressures below 90 kPa. This work takes the first steps towards developing a wearable soft robotic device that can deliver passive therapy at home without the need for a physical therapist or assistant.

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Impact of Electrical Current Stressing on η'-Cu6Sn5 in Electronics Packaging

Impact of Electrical Current Stressing on η'-Cu6Sn5 in Elec...

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International Microsystems, Packaging, Assembly and Circuits Technology (IMPACT)

作者： Shubhayan Mukherjee Shih-kang Lin Department of Materials Science and Engineering National Cheng Kung University Tainan Taiwan Hierarchical Green-Energy Materials (Hi-GEM) Research Center National Cheng Kung University Tainan Taiwan Program on Smart and Sustainable Manufacturing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan Taiwan

ISBN: (数字)9798331532246

ISBN: (纸本)9798331532253

In advanced electronic packaging, the stability of intermetallic compounds (IMCs) under high electric current density is crucial for the reliability of solder joints. Cu 6 Sn 5 , a predominant IMC formed between Sn-based solders and Cu substrates, exists in two allotropes: the high-temperature hexagonal phase and the low-temperature monoclinic η' phase, with a transition temperature of 186°C. This study investigates the effects of electric current on η'-Cu 6 Sn 5 phase, focusing on structural characterization and mechanical properties. Various electric current densities were applied to thermally aged η'-Cu 6 Sn 5 . Synchrotron radiation-based X-ray diffraction (SR-XRD) was used to examine crystallographic changes, while nanoindentation tests assessed mechanical property alterations. These observations contribute to understanding the impact of electric current density on the structural and mechanical behavior of the monoclinic η'-Cu 6 Sn 5 phase.

关键词： Temperature Synchrotrons X-ray diffraction Mechanical factors Stability analysis Current Current density Thermal stability Substrates Electronics packaging

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Crystallization of POSS in a PEG-Based Multiblock Polyurethane: Toward A Hybrid Hydrogel

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MRS Online Proceedings Library 2021年第1期847卷 59-64页

作者： Jian Wu Qing Ge Kelly A. Burke Patrick T. Mather Chemical Engineering Department and Polymer Program Institute of Materials Science University of Connecticut Storrs USA Department of Macromolecular Science and Engineering Case Western Reserve University Cleveland USA

Building upon earlier success in forming materials with crystalline ordering of POSS via the telechelic architecture with POSS end-capping polyethylene glycols, here we report similar ordering in PEG-POSS thermoplastic polyurethane applicable to a novel hybrid hydrogel. Thus, a unique series of hybrid thermoplastic polyurethanes (TPUs) were synthesized using poly(ethylene glycol) (PEG) as soft segment and incorporating an isobutyl-functionalized POSS diol (TMP POSS diol) in the hard segment. The molecular weight of PEG was systematically varied to include 10, 20, and 35 kDa while the mole ratio of PEG to POSS diol (as chain extender) was chosen as 8:1. The diisocyanate employed for TPU polymerization was 4, 4'-methylenebis(phenyl-isocyanate) (MDI). Wide-angle X-ray diffraction (WAXD) studies revealed that both the hydrophilic soft segments (PEG) and hydrophobic hard segments (POSS) can form crystalline structures driven by micro-phase separation, itself due to thermodynamic incompatibility. Differential scanning calorimetry (DSC) and rheological studies revealed that thermal history is important in controlling the crystallization of a POSS-rich nanophase. Increasing the cooling rate monotonically decreases the crystallinity of POSS-rich phase and results in a decrease in the ultimate dynamic storage modulus following POSS crystallization and an increase of the loss angle for temperatures above Tm of PEG and below Tm of POSS. We conclude that both composition and thermal history are key factors in determing the internal network built by the POSS nanophase, which will have a significant influence on the properties of the resulting hybrid hydrogels now being studied.

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Revisiting the Temperature Dependence of Protein Diffusion inside Bacteria: Validity of the Stokes-Einstein Equation

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Physical Review Letters 2022年第1期129卷 018101-018101页

作者： Asmaa A. Sadoon William F. Oliver Yong Wang Department of Physics University of Arkansas Fayetteville Arkansas 72701 USA Materials Science and Engineering Program University of Arkansas Fayetteville Arkansas 72701 USA Department of Physics University of Thi-Qar Nassiriya 64001 Iraq Cell and Molecular Biology Program University of Arkansas Fayetteville Arkansas 72701 USA

Although the transport and mixing of proteins and other molecules inside bacteria rely on the diffusion of molecules, many aspects of the molecular diffusion in bacterial cytoplasm remain unclear or controversial, including how the diffusion-temperature relation follows the Stokes-Einstein equation. In this study, we applied single-particle tracking photoactivated localization microscopy to investigate the diffusion of histonelike nucleoid structuring (HNS) proteins and free dyes in bacterial cytoplasm at different temperatures. Although the diffusion of HNS proteins in both live and dead bacteria increased at higher temperatures and appeared to follow the Arrhenius equation, the diffusion of free dyes decreased at higher temperatures, questioning the previously proposed theories based on superthermal fluctuations. To understand the measured diffusion-temperature relations, we developed an alternative model, in which the bacterial cytoplasm is considered as a polymeric network or mesh. In our model, the Stokes-Einstein equation remains valid, while the polymeric network contributes a significant term to the viscosity experienced by the molecules diffusing in bacterial cytoplasm. Our model was successful in predicting the diffusion-temperature relations for both HNS proteins and free dyes in bacteria. In addition, we systematically examined the predicted diffusion-temperature relations with different parameters in the model, and predicted the possible existence of phase transitions.

关键词： Anomalous diffusion Diffusion Intracellular transport Network diffusion Proteins

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Graphene calorimetric single-photon detector

arXiv

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arXiv 2024年

作者： Huang, Bevin Arnault, Ethan G. Jung, Woochan Fried, Caleb Russell, B. Jordan Watanabe, Kenji Taniguchi, Takashi Henriksen, Erik A. Englund, Dirk Lee, Gil-Ho Fong, Kin Chung Intelligence Community Postdoctoral Research Fellowship Program Massachusetts Institute of Technology CambridgeMA02139 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Pohang University of Science and Technology Pohang790-784 Korea Republic of Department of Physics Washington University in St. Louis St. LouisMO United States Research Center for Electronic and Optical Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan RTX BBN Technologies Quantum Engineering and Computing Group CambridgeMA02138 United States

Single photon detectors (SPDs) [1, 2] are essential technology in quantum science, quantum network, biology, and advanced imaging [3-5]. To detect the small quantum of energy carried in a photon, conventional SPDs rely on energy excitation across either a semiconductor bandgap or superconducting gap. While the energy gap suppresses the false-positive error, it also sets an energy scale that can limit the detection efficiency of lower energy photons and spectral bandwidth of the SPD [6-8]. Here, we demonstrate an orthogonal approach to detect single near-infrared photons using graphene calorimeters [9-13]. By exploiting the extremely low heat capacity of the pseudo-relativistic electrons in graphene near its charge neutrality point [14], we observe an electron temperature rise up to ∼2 K using a hybrid Josephson junction. In this proof-of-principle experiment, we achieve an intrinsic quantum efficiency of 87% (75%) with dark count © 2024, CC BY.

关键词： Particle beams

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Coherent X-ray Spectroscopy Elucidates Nanoscale Dynamics of Plasma-Enhanced Thin-Film Growth

arXiv

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arXiv 2023年

作者： Myint, Peco Woodward, Jeffrey M. Wang, Chenyu Zhang, Xiaozhi Wiegart, Lutz Fluerasu, Andrei Headrick, Randall L. Eddy, Charles R. Ludwig, Karl F. Department of Physics Division of Materials Science and Engineering Boston University BostonMA United States Electronics Science and Technology Division U.S. Naval Research Laboratory WashingtonDC United States Department of Physics and Materials Science Program University of Vermont Burlington United States National Synchrotron Light Source II Brookhaven National Laboratory Upton United States

Sophisticated thin film growth techniques increasingly rely on the addition of a plasma component to open or widen a processing window, particularly at low temperatures. However, the addition of the plasma into the growth environment also complicates the surface dynamical evolution. Taking advantage of continued increases in accelerator-based X-ray source brilliance, this real-time study uses X-ray Photon Correlation Spectroscopy (XPCS) to elucidate the nanoscale surface dynamics during Plasma-Enhanced Atomic Layer Deposition (PE-ALD) of an epitaxial indium nitride film. XPCS examines the evolution of the coherent X-ray scattering speckle pattern, which is a fingerprint of the unique sample microstructure at each moment in time. In PE-ALD, ultrathin films are synthesized from repeated cycles of alternating self-limited surface reactions induced by temporally-separated pulses of material precursor and plasma reactant, allowing the influence of each on the evolving morphology to be examined. During the heteroepitaxial 3D growth examined here, sudden changes in surface structure during initial film growth, consistent with numerous overlapping stress-relief events, are observed. When the film becomes continuous, the nanoscale surface morphology abruptly becomes long-lived with correlation time spanning the period of the experiment. Throughout the growth experiment, there is a consistent repeating pattern of correlations associated with the cyclic growth process, which is modeled as transitions between different surface states. The plasma exposure does not simply freeze in a structure that is then built upon in subsequent cycles, but rather there is considerable surface evolution during all phases of the growth cycle. © 2023, CC BY.

关键词： Ultrathin films

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Predicting the Heterogeneous Chemo-Mechano-Biological Degeneration of Cartilage Using 3-D Biphasic Finite Elements

SSRN

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SSRN 2024年

作者： Rahman, Muhammed Masudur Watton, Paul N. Neu, Corey P. Pierce, David M. Department of Mechanical Engineering University of Connecticut Storrs CT United States Department of Computer Science Insigneo Institute for in silico Medicine University of Sheffield Sheffield United Kingdom Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh United States Paul M. Rady Department of Mechanical Engineering University of Colorado BoulderCO United States Biomedical Engineering Program University of Colorado BoulderCO United States BioFrontiers Institute University of Colorado BoulderCO United States Department of Biomedical Engineering University of Connecticut Storrs CT United States

We establish a novel chemo-mechano-biological (CMB) modeling framework for cartilage implemented within 3-D nonlinear, finite element analyses. The framework integrates a nonlinear biphasic constitutive model with a signaling-pathways biochemical model to capture the coupled effects of mechanical stimuli, biochemical factors, and cellular activity on cartilage degeneration and remodeling. Through finite element simulations of cyclic compression, we explored cartilage degeneration similar to early-stage osteoarthritis (OA), demonstrating that oxygen-dependent, depth-specific metabolic activity yields more realistic patterns of degeneration compared to our previous models. Specifically, our results align with experimental observations, capturing depth-dependent cartilage degradation most pronounced in the superficial zone. Incorporating these insights, our framework provides a platform to investigate mechanisms of cartilage degeneration and simulate therapeutic interventions. We previously developed automated and publicly available tools to generate patient-specific knee models from MR Images, altogether enabling personalized diagnostics/prognostics and pre-/post-operative planning. Our CMB framework is also publicly available for academic use at https://***/imLab/FEVGnR-Plugin, offering a robust basis for advancing research and clinical strategies in understanding and managing osteoarthritis. © 2024, The Authors. All rights reserved.

关键词： Cartilage

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Quantum simulation of an extended Dicke model with a magnetic solid

Communications Materials

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Communications materials 2024年第1期5卷 1-9页

作者： Marquez Peraca, Nicolas Li, Xinwei Moya, Jaime M. Hayashida, Kenji Kim, Dasom Ma, Xiaoxuan Neubauer, Kelly J. Fallas Padilla, Diego Huang, Chien-Lung Dai, Pengcheng Nevidomskyy, Andriy H. Pu, Han Morosan, Emilia Cao, Shixun Bamba, Motoaki Kono, Junichiro Department of Physics and Astronomy Rice University HoustonTX United States Department of Physics California Institute of Technology PasadenaCA United States Applied Physics Graduate Program Smalley–Curl Institute Rice University HoustonTX United States Division of Applied Physics Graduate School of Engineering Hokkaido University Hokkaido Japan Department of Electrical and Computer Engineering Rice University HoustonTX United States Department of Physics International Center of Quantum and Molecular Structures and Materials Genome Institute Shanghai University Shanghai China Department of Physics and Center for Quantum Frontiers of Research and Technology National Cheng Kung University Tainan Taiwan Department of Chemistry Rice University HoustonTX United States Department of Physics I Kyoto University Kyoto Japan The Hakubi Center for Advanced Research Kyoto University Kyoto Japan PRESTO Japan Science and Technology Agency Saitama Japan Department of Physics Yokohama National University Yokohama Japan Department of Materials Science and NanoEngineering Rice University HoustonTX United States

The Dicke model describes the cooperative interaction of an ensemble of two-level atoms with a single-mode photonic field and exhibits a quantum phase transition as a function of light–matter coupling strength. Extending this model by incorporating short-range atom–atom interactions makes the problem intractable but is expected to produce new physical phenomena and phases. Here, we simulate such an extended Dicke model using a crystal of ErFeO3, where the role of atoms (photons) is played by Er3+ spins (Fe3+ magnons). Through terahertz spectroscopy and magnetocaloric effect measurements as a function of temperature and magnetic field, we demonstrated the existence of a novel atomically ordered phase in addition to the superradiant and normal phases that are expected from the standard Dicke model. Further, we elucidated the nature of the phase boundaries in the temperature–magnetic-field phase diagram, identifying both first-order and second-order phase transitions. These results lay the foundation for studying multiatomic quantum optics models using well-characterized many-body solid-state systems. © The Author(s) 2024.

关键词： Atoms

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Terahertz Time-Domain Imaging for Radiotherapy Treatment Monitoring in Pancreatic Ductal Adenocarcinoma

Terahertz Time-Domain Imaging for Radiotherapy Treatment Mon...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Debamitra Chakraborty Bradley N. Mills Jing Cheng Ivan Komissarov Scott Gerber Roman Sobolewski Materials Science Graduate Program University of Rochester Rochester New York Laboratory for Laser Energetics University of Rochester Rochester New York Department of Surgery University of Rochester Medical Center Rochester New York Department of Electrical and Computer Engineering University of Rochester Rochester New York

ISBN: (纸本)9798350369311

Terahertz time-domain imaging was performed of stereotactic body radiotherapy-treated murine pancreatic ductal adenocarcinoma (PDAC) with a high spatial resolution. To generate 2D maps of the tissue samples, the refractive index and absorption coefficient were used as imaging markers extracted with the maximum a-posteriori probability (MAP) estimation algorithm. The results were then compared with the terahertz maps of untreated murine PDAC tissue samples and demonstrated that terahertz imaging can probe physical changes with high sensitivity in the tissue post treatment.

关键词： Maximum a posteriori estimation Terahertz wave imaging Laser theory Sensitivity Refractive index Radiation therapy Time-domain analysis Spatial resolution Probes Monitoring

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