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Structural changes induced by electric currents in a single crystal of Pr2CuO4

Physical Review Materials 2023年第8期7卷 083803-083803页

作者： Susmita Roy Feng Ye Zachary Morgan Kabir Mathur Anish Parulekar Syed I. A. Jalali Yu Zhang Gang Cao Nobu-Hisa Kaneko Martin Greven Rishi Raj Dmitry Reznik Department of Physics University of Colorado at Boulder Boulder Colorado 80309 USA Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37830 USA Materials Science and Engineering Program Department of Mechanical Engineering University of Colorado Boulder Boulder Colorado 80309 USA National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki 305-8563 Japan School of Physics and Astronomy University of Minnesota Minneapolis Minnesota 55455 USA Center for Experiments on Quantum Materials University of Colorado at Boulder Boulder Colorado 80309 USA

We demonstrate an approach to the structural and electronic property modification of perovskites, focusing on Pr2CuO4, an undoped parent compound of a class of electron-doped copper-oxide superconductors. Currents were passed parallel or perpendicular to the copper oxygen layers with the voltage ramped up until a rapid drop in the resistivity was achieved, a process referred to as “flash.” The current was then further increased tenfold in current-control mode. This state was quenched by immersion into liquid nitrogen. Flash can drive many compounds into different atomic structures with new properties, whereas the quench freezes them into a long-lived state. Single-crystal neutron diffraction of as-grown and modified Pr2CuO4 revealed a 10×10 superlattice due to oxygen-vacancy order. The diffraction peak intensities of the superlattice of the modified sample were significantly enhanced relative to the pristine sample. Raman-active phonons in the modified sample were considerably sharper. Measurements of electrical resistivity, magnetization, and two-magnon Raman scattering indicate that the modification affected only the Pr-O layers, but not the Cu-O planes. These results point to enhanced oxygen-vacancy order in the modified samples well beyond what can be achieved without passing electrical current. Our work opens a new avenue toward electric field/quench control of structure and properties of layered perovskite oxides.

关键词： Electrical properties Electroluminescence Magnetic order Magnetic susceptibility Superconductivity

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The Effects of Boron Doping on the Bulk and Surface Acoustic Phonons in Single-Crystal Diamond

arXiv

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arXiv 2022年

作者： Guzman, Erick Kargar, Fariborz Angeles, Frank Meidanshahi, Reza Vatan Grotjohn, Timothy A. Hardy, Aaron Muehle, Matthias Wilson, Richard B. Goodnik, Stephen Balandin, Alexander A. Nano-Device Laboratory Phonon Optimized Engineered Materials Center Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Department of Mechanical Engineering Materials Science and Engineering Program University of California RiversideCA92521 United States School of Electrical Computer and Energy Engineering Arizona State University TempeAZ85281 United States Department of Electrical and Computer Engineering Michigan State University East LansingMI48824 United States Fraunhofer USA Center Midwest East LansingMI48824 United States

We report the results of the investigation of bulk and surface acoustic phonons in the undoped and boron-doped single-crystal diamond films using the Brillouin-Mandelstam light scattering spectroscopy. The evolution of the optical phonons in the same set of samples was monitored with Raman spectroscopy. It was found that the frequency and the group velocity of acoustic phonons decrease non-monotonically with the increasing boron doping concentration, revealing pronounced phonon softening. The change in the velocity of the shear horizontal and the high-frequency pseudo-longitudinal acoustic phonons in the degenerately doped diamond, as compared to the undoped diamond, was as large as ~ 15% and ~12%, respectively. As a result of boron doping, the velocity of the bulk longitudinal and transverse acoustic phonons decreased correspondingly. The frequency of the optical phonons was unaffected at low boron concentration but experienced a strong decrease at the high doping level. The density-functional-theory calculations of the phonon band structure for the pristine and highly-doped sample confirm the phonon softening as a result of boron doping in diamond. The obtained results have important implications for thermal transport in heavily doped diamond, which is a promising material for ultra-wide-band-gap electronics. Copyright © 2022, The Authors. All rights reserved.

关键词： Density functional theory

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Controllable directional excitation and emission of nanoemitters by a subwavelength mie antenna

Controllable directional excitation and emission of nanoemit...

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2020 Frontiers in Optics Conference, FiO 2020

作者： Fang, Jie Wang, Mingsong Yao, Kan Zheng, Yuebing Materials Science and Engineering Program Texas Materials Institute The University of Texas at Austin AustinTX78712 United States Walker Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States

ISBN: (纸本)9781943580804

We derive a universal multipolar model for dipole-sphere hybrids, introduce single subwavelength silicon nanospheres at visible wavelengths with facile size control, and demonstrate controllable directional excitation and emission of nanoemitters (e.g. WS2, MoS2) for on-demand emission property modulations. © OSA 2020 © 2020 The Author(s)

关键词： Nanospheres

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Enhanced Thrombolytic Effect Induced by Acoustic Cavitation Generated from Nitrogen-Doped Annealed Nanodiamond Particles

SSRN

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SSRN 2023年

作者： Zhang, Qi Xue, Honghui Zhang, Haijun Chen, Yuqi Liu, Zijun Fan, Zheng Guo, Xiasheng Wu, Xiaoge Zhang, Dong Tu, Juan Department of Physics Collaborative Innovation Center of Advanced Microstructure Nanjing University Nanjing210093 China Wuxi Vocational Institute of Commerce Jiangsu Wuxi214153 China Shanghai Tenth People's Hospital School of Medicine Tongji University Shanghai200092 China National United Engineering Laboratory for Biomedical Material Modification Branden Industrial Park Shandong Dezhou251100 China School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore639798 Singapore Environment Science and Engineering College Yangzhou University Jiangsu Yangzhou225009 China

In biomedical research, ultrasonic cavitation, especially inertial cavitation (IC) has attracted extensive attentions due to its ability to induce mechanical, chemical and thermal effects. Like ultrasound contrast agent (UCA) microbubbles or droplets, acoustic cavitation can be effectively triggered beyond a certain pressure threshold through the interaction between ultrasound and nucleation particles, leading to an enhanced thrombolytic effect. As a newly developed nanocarbon material, nitrogen-doped annealed nanodiamond (N-AND) has shown promising catalytic performance. To further explore its effects on ultrasonic cavitation, N-AND was synthesized at the temperature of 1000℃. After systematic material characterization, the potential of N-AND to induce enhanced IC activity was assessed for the first time by using passive cavitation detection (PCD). Based on experiments performed at varied material suspension concentration and cycle number, N-AND demonstrated a strong capability to generate significant cavitation characteristics, indicating the formation of stable bubbles from the surface of the materials. Furthermore, N-AND was applied in the in vitro thrombolysis experiments to verify its contribution to ultrasound thrombolysis. The influence of surface hydrophobicity on the cavitation potentials of ND and N-AND was innovatively discussed in combination with the theory of mote-induced nucleation. It is found that the cavitation stability of N-AND was better than that of the commercial UCA microbubbles. This study would provide better understanding of the potential of novel carbonous nanomaterials as cavitation nuclei and is expected to provide guidance for their future biomedical and industrial applications. © 2023, The Authors. All rights reserved.

关键词： Nucleation

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Assessing the aneurysm occlusion efficacy of a shear-thinning biomaterial in a 3D-printed model

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Journal of the mechanical Behavior of biomedical Materials 2022年第0期130卷 105156页

作者： Schroeder, Grant Edalati, Masoud Tom, Gregory Kuntjoro, Nicole Gutin, Mark Gurian, Melvin Cuniberto, Edoardo Hirth, Elisabeth Martiri, Alessia Sposato, Maria Teresa Aminzadeh, Selda Eichenbaum, James Alizadeh, Parvin Baidya, Avijit Haghniaz, Reihaneh Nasiri, Rohollah Kaneko, Naoki Mansouri, Abraham Khademhosseini, Ali Sheikhi, Amir Department of Bioengineering University of California Los Angeles 410 Westwood Plaza Los AngelesCA90095 United States University of California Los Angeles 570 Westwood Plaza Los AngelesCA90095 United States David Geffen School of Medicine at UCLA Los AngelesCA United States Department of Mechanical Engineering Rowan University Rowan Hall 201 Mullica Hill Rd GlassboroNJ08028 United States Biomaterials Innovation Research Center Division of Biomedical Engineering Department of Medicine Brigham and Women's Hospital Harvard Medical School CambridgeMA02139 United States Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of Technology CambridgeMA02139 United States Department of Materials Science & Engineering Faculty of Engineering & Technology Tarbiat Modares University Tehran Iran Los AngelesCA90024 United States Department of Radiological Sciences David Geffen School of Medicine University of California Los Angeles 10833 Le Conte Ave Los AngelesCA90095 United States Department of Mechanical Engineering Higher College of Technology Dubai15825 United Arab Emirates Department of Chemical Engineering The Pennsylvania State University University Park PA16802 United States Department of Biomedical Engineering The Pennsylvania State University University Park PA16802 United States

Metallic coil embolization is a common method for the endovascular treatment of visceral artery aneurysms (VAA) and visceral artery pseudoaneurysms (VAPA);however, this treatment is suboptimal due to the high cost of coils, incomplete volume occlusion, poor reendothelialization, aneurysm puncture, and coil migration. Several alternative treatment strategies are available, including stent flow diverters, glue embolics, gelfoam slurries, and vascular mesh plugs—each of which have their own disadvantages. Here, we investigated the in vitro capability of a shear-thinning biomaterial (STB), a nanocomposite hydrogel composed of gelatin and silicate nanoplatelets, for the minimally-invasive occlusion of simple necked aneurysm models. We demonstrated the injectability of STB through various clinical catheters, engineered an in vitro testing apparatus to independently manipulate aneurysm neck diameter, fluid flow rate, and flow waveform, and tested the stability of STB within the models under various conditions. Our experiments show that STB is able to withstand at least 1.89 Pa of wall shear stress, as estimated by computational fluid dynamics. STB is also able to withstand up to 10 mL s−1 pulsatile flow with a waveform mimicking blood flow in the human femoral artery and tolerate greater pressure changes than those in the human aorta. We ultimately found that our in vitro system was limited by supraphysiologic pressure changes caused by aneurysm models with low compliance. © 2022 Elsevier Ltd

关键词： Shear thinning

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Experimental Validation of a Safe Controller Integration Scheme for Connected Automated Trucks

arXiv

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arXiv 2022年

作者： Alan, Anil He, Chaozhe R. Molnar, Tamas G. Mathew, Johaan C. Bell, A. Harvey Orosz, Gábor The Department of Mechanical Engineering University of Michigan Ann ArborMI48109 United States Plus.ai Inc. Santa ClaraCA95014 United States The Department of Mechanical and Civil Engineering California Institute of Technology PasadenaCA91125 United States Visteon Corporation Van Buren Township MI48111 United States Multidisciplinary Design Program University of Michigan Ann ArborMI48109 United States The Department of Civil and Environmental Engineering University of Michigan Ann ArborMI48109 United States

Accomplishing safe and efficient driving is one of the predominant challenges in the controller design of connected automated vehicles (CAVs). It is often more convenient to address these goals separately and integrate the resulting controllers. In this study, we propose a controller integration scheme to fuse performance-based controllers and safety-oriented controllers safely for the longitudinal motion of a CAV. The resulting structure is compatible with a large class of controllers, and offers flexibility to design each controller individually without affecting the performance of the others. We implement the proposed safe integration scheme on a connected automated truck using an optimal-in-energy controller and a safety-oriented connected cruise controller. We validate the premise of the safe integration through experiments with a full-scale truck in two scenarios: a controlled experiment on a test track and a real-world experiment on a public highway. In both scenarios, we achieve energy efficient driving without violating safety. Copyright © 2022, The Authors. All rights reserved.

关键词： Controllers

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Lifecycles, pipelines, and value chains: toward a focus on events in responsible artificial intelligence for health

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AI and Ethics 2024年 1-14页

作者： Donia, Joseph Oyefeso, Lola Embuldeniya, Gayathri Whyne, Cari Burns, David Boyer, Philip Razmjou, Helen Shaw, James A. Institute of Health Policy Management & Evaluation Dalla Lana School of Public Health University of Toronto Toronto Canada Department of Biology Faculty of Arts and Science University of Toronto Toronto Canada Department of Physical Therapy Temerty Faculty of Medicine University of Toronto Toronto Canada Holland Bone and Joint Program Sunnybrook Research Institute Sunnybrook Health Sciences Centre Toronto Canada Institute of Biomedical Engineering Faculty of Applied Science and Engineering University of Toronto Toronto Canada Institute of Medical Sciences Temerty Faculty of Medicine University of Toronto Toronto Canada Division of Orthopedic Surgery Department of Surgery Temerty Faculty of Medicine University of Toronto Toronto Canada Joint Centre for Bioethics Dalla Lana School of Public Health University of Toronto Toronto Canada

Process-oriented approaches to the responsible development, implementation, and oversight of artificial intelligence (AI) systems have proliferated in recent years. Variously referred to as lifecycles, pipelines, or value chains, these approaches demonstrate a common focus on systematically mapping key activities and normative considerations throughout the development and use of AI systems. At the same time, these approaches risk focusing on proximal activities of development and use at the expense of a focus on the events and value conflicts that shape how key decisions are made in practice. In this article we report on the results of an ‘embedded’ ethics research study focused on SPOTT– a ‘Smart Physiotherapy Tracking Technology’ employing AI and undergoing development and commercialization at an academic health sciences centre. Through interviews and focus groups with the development and commercialization team, patients, and policy and ethics experts, we suggest that a more expansive design and development lifecycle shaped by key events offers a more robust approach to normative analysis of digital health technologies, especially where those technologies’ actual uses are underspecified or in flux. We introduce five of these key events, outlining their implications for responsible design and governance of AI for health, and present a set of critical questions intended for others doing applied ethics and policy work. We briefly conclude with a reflection on the value of this approach for engaging with health AI ecosystems more broadly.

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Global Health Benefits of Policies to Reduce On-Road Vehicle Pollution Through 2040

SSRN

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SSRN 2024年

作者： Jin, Lingzhi Benoit, Jonathan Nawaz, M. Omar Rodrigues, Patricia Ferrini Wiecko, Patrick Miller, Joshua Alvarez, Gabriel Henze, Daven K. Osipova, Liudmila Anenberg, Susan The Interna+onal Council on Clean Transporta+on. Washington 1500 K Street NW Suite 650 WashingtonDC20005 United States Milken Ins+tute School of Public Health George Washington University 2121 Eye Street NW WashingtonDC20052 United States Environmental Engineering Program University of Colorado Boulder 4001 Discovery Drive BoulderCO80309-0607 United States Department of Mechanical Engineering University of Colorado Boulder 1111 Engineering Drive. UCB 427. BoulderCO80309-0427 United States

Background: Air pollution from road transport-related emissions is a well-documented risk to human health. Our study assessed these health impacts under current and potential emission control policies in 186 countries and territories, including 13,135 urban areas, until 2040, at a 1km resolution. Methods: We evaluated 15 scenarios based on various policy combinations using ICCT’s Roadmap model for emissions and GEOS-Chem Adjoint v35n for pollutant concentrations. We estimated mortality impacts following GBD 2019 methodology, and an epidemiologically-derived concentration-response model for NO2-attributable pediatric asthma impacts. Findings: Implementing all measures identified is projected to avoid 1·9 million (95% CI of the central risk estimate 1·3 million-2·4 million) premature deaths and 1·4 million (95% CI of the central risk estimate 0·7 million-1·7 million) new cases of paediatric asthma cumulatively from 2023 to 2040. These health benefits differ by region and age group. Adults aged 65 and older account for 70% of avoidable years of life lost, and children under 5 represent 50% of avoidable new paediatric asthma cases. In countries without Euro 6/VI-equivalent standards, implementing these could achieve 64% and 71% of the total benefits of all emission control measures combined for avoidable premature deaths and new paediatric asthma cases respectively. Developing countries and urban areas hold substantial mitigation potential in new pediatric asthma cases. Interpretation: Regional disparities in road transport-attributable health burdens are projected to grow without further policies. Stronger policies are needed to mitigate these health impacts, particularly for vulnerable groups like children and older ***: This project was supported by FIA Foundation (15.17.18/22), Clean Air Fund (001385), and Pisces Foundation (22-00845). Patrick Wiecko was supported by NASA 80NSSC19K0193 and *** of Interest: We declare no competing int

关键词： Developing countries

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Author Correction: Emergence of melt and glass states of halide perovskite semiconductors

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Nature Reviews Materials 2025年 1页

作者： Akash Singh David B. Mitzi Department of Mechanical Engineering and Materials Science Duke University Durham NC USA University Program in Materials Science and Engineering Duke University Durham NC USA Department of Chemistry Duke University Durham NC USA

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3D microenvironment attenuates simulated microgravity-mediated changes in T cell transcriptome

Research Square

引用

Research Square 2022年

作者： ElGindi, Mei Sapudom, Jiranuwat Laws, Praveen Garcia-Sabate, Anna Daqaq, Mohamad Teo, Jeremy Laboratory for Immuno Bioengineering Research and Applications Division of Engineering New York University Abu Dhabi POBox Abu Dhabi129188 United Arab Emirates Laboratory of Applied Nonlinear Dynamics Division of Engineering New York University Abu Dhabi POBox Abu Dhabi129188 United Arab Emirates Department of Mechanical and Biomedical Engineering New York University BrooklynNY11201 United States

Human space travel and exploration are of interest to both the industrial and scientific community. However, there are many adverse effects of spaceflight on human physiology. In particular, there is a lack of understanding to the extent by which microgravity affects the immune system. T cells, key players of the adaptive immune system and long term immunity, are present not only in blood circulation, but also reside within tissue. As of yet, studies investigating the effects of microgravity on T cells are limited to peripheral blood or traditional 2D cell culture that recapitulates circulating blood. To better mimic interstitial tissue, 3D cell culture has been well established for physiologically and pathologically relevant models. In this work, we utilize 2D and 3D cell culture to gain an understanding of how simulated microgravity affects both circulating and tissue resident T cells. T cells were studied in both resting and activated stages. We found that 3D cell culture attenuates the effects of simulated microgravity on the T cells transcriptome and nuclear irregularities compared to 2D cell culture. Interestingly, simulated microgravity appears to have less effect on activated T cells compared to those in the resting stage. Overall, our work provides novel insights into the effects of simulated microgravity on circulating and tissue resident T cells which could provide benefits for the health of space travelers. © 2022, CC BY.

关键词： T-cells

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