1
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White TG, Dai J, Riley D. Dynamic and transient processes in warm dense matter. Philos Trans A Math Phys Eng Sci 2023; 381:20220223. [PMID: 37393937 PMCID: PMC10315215 DOI: 10.1098/rsta.2022.0223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 05/22/2023] [Indexed: 07/04/2023]
Abstract
In this paper, we discuss some of the key challenges in the study of time-dependent processes and non-equilibrium behaviour in warm dense matter. We outline some of the basic physics concepts that have underpinned the definition of warm dense matter as a subject area in its own right and then cover, in a selective, non-comprehensive manner, some of the current challenges, pointing along the way to topics covered by the papers presented in this volume. This article is part of the theme issue 'Dynamic and transient processes in warm dense matter'.
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Affiliation(s)
- Thomas G. White
- Department of Physics, University of Nevada, Reno, NV 89557, USA
| | - Jiayu Dai
- College of Science, National University of Defense Technology, Changsha 410073, People’s Republic of China
| | - David Riley
- School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK
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2
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Giri A, Walton SG, Tomko J, Bhatt N, Johnson MJ, Boris DR, Lu G, Caldwell JD, Prezhdo OV, Hopkins PE. Ultrafast and Nanoscale Energy Transduction Mechanisms and Coupled Thermal Transport across Interfaces. ACS Nano 2023; 17:14253-14282. [PMID: 37459320 PMCID: PMC10416573 DOI: 10.1021/acsnano.3c02417] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 06/06/2023] [Indexed: 08/09/2023]
Abstract
The coupled interactions among the fundamental carriers of charge, heat, and electromagnetic fields at interfaces and boundaries give rise to energetic processes that enable a wide array of technologies. The energy transduction among these coupled carriers results in thermal dissipation at these surfaces, often quantified by the thermal boundary resistance, thus driving the functionalities of the modern nanotechnologies that are continuing to provide transformational benefits in computing, communication, health care, clean energy, power recycling, sensing, and manufacturing, to name a few. It is the purpose of this Review to summarize recent works that have been reported on ultrafast and nanoscale energy transduction and heat transfer mechanisms across interfaces when different thermal carriers couple near or across interfaces. We review coupled heat transfer mechanisms at interfaces of solids, liquids, gasses, and plasmas that drive the resulting interfacial heat transfer and temperature gradients due to energy and momentum coupling among various combinations of electrons, vibrons, photons, polaritons (plasmon polaritons and phonon polaritons), and molecules. These interfacial thermal transport processes with coupled energy carriers involve relatively recent research, and thus, several opportunities exist to further develop these nascent fields, which we comment on throughout the course of this Review.
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Affiliation(s)
- Ashutosh Giri
- Department
of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Scott G. Walton
- Plasma
Physics Division, Naval Research Laboratory, Washington, DC 22032, United States
| | - John Tomko
- Department
of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Niraj Bhatt
- Department
of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Michael J. Johnson
- Plasma
Physics Division, Naval Research Laboratory, Washington, DC 22032, United States
| | - David R. Boris
- Plasma
Physics Division, Naval Research Laboratory, Washington, DC 22032, United States
| | - Guanyu Lu
- Department
of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Joshua D. Caldwell
- Department
of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Interdisciplinary
Materials Science, Vanderbilt University, Nashville, Tennessee 37235, United States
- Vanderbilt
Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Oleg V. Prezhdo
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
- Department
of Physics and Astronomy, University of
Southern California, Los Angeles, California 90089, United States
| | - Patrick E. Hopkins
- Department
of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
- Department
of Materials Science and Engineering, University
of Virginia, Charlottesville, Virginia 22904, United States
- Department
of Physics, University of Virginia, Charlottesville, Virginia 22904, United States
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3
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Kurniawan D, Mathew J, Rahardja MR, Pham HP, Wong PC, Rao NV, Ostrikov KK, Chiang WH. Plasma-Enabled Graphene Quantum Dot Hydrogels as Smart Anticancer Drug Nanocarriers. Small 2023; 19:e2206813. [PMID: 36732883 DOI: 10.1002/smll.202206813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/10/2023] [Indexed: 05/18/2023]
Abstract
One of the major challenges on the way to low-cost, simple, and effective cancer treatments is the lack of smart anticancer drug delivery materials with the requisite of site-specific and microenvironment-responsive properties. This work reports the development of plasma-engineered smart drug nanocarriers (SDNCs) containing chitosan and nitrogen-doped graphene quantum dots (NGQDs) for drug delivery in a pH-responsive manner. Through a customized microplasma processing, a highly cross-linked SDNC with only 4.5% of NGQD ratio can exhibit enhanced toughness up to threefold higher than the control chitosan group, avoiding the commonly used high temperatures and toxic chemical cross-linking agents. The SDNCs demonstrate improved loading capability for doxorubicin (DOX) via π-π interactions and stable solid-state photoluminescence to monitor the DOX loading and release through the Förster resonance energy transfer (FRET) mechanism. Moreover, the DOX loaded SDNC exhibits anticancer effects against cancer cells during cytotoxicity tests at minimum concentration. Cellular uptake studies confirm that the DOX loaded SDNC can be successfully internalized into the nucleus after 12 h incubation period. This work provides new insights into the development of smart, environmental-friendly, and biocompatible nanographene hydrogels for the next-generation biomedical applications.
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Affiliation(s)
- Darwin Kurniawan
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
| | - Jacob Mathew
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
| | - Michael Ryan Rahardja
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
| | - Hoang-Phuc Pham
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
| | - Pei-Chun Wong
- Graduate Institute of Biomedical Optomechatronics, College of Biomedical Engineering, Taipei Medical University, Taipei, 110, Taiwan
| | - Neralla Vijayakameswara Rao
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
| | - Kostya Ken Ostrikov
- School of Chemistry and Physics and QUT Centre for Materials Science, Queensland University of Technology (QUT), Brisbane, Queensland, 4000, Australia
| | - Wei-Hung Chiang
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
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Hollerbach R, Kim EJ. Effects of Stochastic Noises on Limit-Cycle Oscillations and Power Losses in Fusion Plasmas and Information Geometry. Entropy (Basel) 2023; 25:e25040664. [PMID: 37190453 PMCID: PMC10137813 DOI: 10.3390/e25040664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/01/2023] [Accepted: 04/13/2023] [Indexed: 05/17/2023]
Abstract
We investigate the effects of different stochastic noises on the dynamics of the edge-localised modes (ELMs) in magnetically confined fusion plasmas by using a time-dependent PDF method, path-dependent information geometry (information rate, information length), and entropy-related measures (entropy production, mutual information). The oscillation quenching occurs due to either stochastic particle or magnetic perturbations, although particle perturbation is more effective in this amplitude diminishment compared with magnetic perturbations. On the other hand, magnetic perturbations are more effective at altering the oscillation period; the stochastic noise acts to increase the frequency of explosive oscillations (large ELMs) while decreasing the frequency of more regular oscillations (small ELMs). These stochastic noises significantly reduce power and energy losses caused by ELMs and play a key role in reproducing the observed experimental scaling relation of the ELM power loss with the input power. Furthermore, the maximum power loss is closely linked to the maximum entropy production rate, involving irreversible energy dissipation in non-equilibrium. Notably, over one ELM cycle, the information rate appears to keep almost a constant value, indicative of a geodesic. The information rate is also shown to be useful for characterising the statistical properties of ELMs, such as distinguishing between explosive and regular oscillations and the regulation between the pressure gradient and magnetic fluctuations.
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Affiliation(s)
- Rainer Hollerbach
- Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, UK
| | - Eun-Jin Kim
- Centre for Fluid and Complex Systems, Coventry University, Priory St, Coventry CV1 5FB, UK
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5
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Carrington ME, Kunstatter G, Phillips CD, Rubio ME. Isotropization of a Rotating and Longitudinally Expanding ϕ4 Scalar System. Entropy (Basel) 2022; 24:1612. [PMID: 36359701 PMCID: PMC9689836 DOI: 10.3390/e24111612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/01/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
We study numerically the evolution of an expanding system of scalar fields. The initial configuration is non-isotropic and rotating. We calculate the energy-momentum tensor and angular momentum vector of the system. We compare the time scales associated with the isotropization of the transverse and longitudinal pressures, and the decay of the initial angular momentum. We show that even a fairly large initial angular momentum decays significantly faster than the pressure anisotropy.
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Affiliation(s)
- Margaret E. Carrington
- Department of Physics, Brandon University, Brandon, MB R7A 6A9, Canada
- Winnipeg Institute for Theoretical Physics, Winnipeg, MB R3T 2N2, Canada
| | - Gabor Kunstatter
- Winnipeg Institute for Theoretical Physics, Winnipeg, MB R3T 2N2, Canada
- Department of Physics, University of Winnipeg, Winnipeg, MB R3M 2E9, Canada
- Department of Physics, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | | | - Marcelo E. Rubio
- Department of Physics, Brandon University, Brandon, MB R7A 6A9, Canada
- Winnipeg Institute for Theoretical Physics, Winnipeg, MB R3T 2N2, Canada
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6
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Zhang H, Liu X, Li Y, Wu W, Gu Y, Zhang T. Study on the mechanism of thrombus ablation in vitro by burst-mode femtosecond laser. J Biophotonics 2022; 15:e202200197. [PMID: 35894214 DOI: 10.1002/jbio.202200197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
The burst-mode femtosecond laser has the potential to be a novel thrombus removal technique. This paper proposed to investigate the mechanism of thrombus ablation in vitro by burst-mode femtosecond laser. A simulation model of the interaction between femtosecond laser and thrombus was established. An in vitro thrombus model was prepared. Combined with the high-speed galvanometer and femtosecond laser, the ablation experiments in vitro were performed. The experimental results showed that the ablative threshold was 0.27 times and the efficiency was about 1.4 times of burst-mode femtosecond laser as those of traditional mode femtosecond laser. These phenomena were related to the residual temperature and free electrons on the thrombus surface, which confirmed the simulating results and had relationship with incubation effects. The high ablative efficiency and safety of burst-mode femtosecond laser for thrombus ablation were verified, which may help to achieve the femtosecond pulse output through flexible fiber easily and stably. The burst-mode femtosecond laser represents an important technological advancement of the method in terms of endovascular treatment with femtosecond laser.
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Affiliation(s)
- Haitao Zhang
- Center for Photonics and Electronics, Department of Precision Instrument, Tsinghua University, Beijing, China
| | - Xiaozheng Liu
- School of Optics and Photonics, Beijing Institute of Technology, Beijing, China
| | - Younan Li
- School of Clinical Medicine, Tsinghua University, Beijing, China
- Department of Vascular Surgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
| | - Weiwei Wu
- Department of Vascular Surgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
| | - Ying Gu
- School of Optics and Photonics, Beijing Institute of Technology, Beijing, China
- Department of Laser Medicine, First Medical Center of PLA General Hospital, Beijing, China
| | - Tong Zhang
- Department of Vascular Surgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
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7
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Li Z, Mahajan A, Andaraarachchi HP, Lee Y, Kortshagen UR. Water-Soluble Luminescent Silicon Nanocrystals by Plasma-Induced Acrylic Acid Grafting and PEGylation. ACS Appl Bio Mater 2022; 5:105-112. [PMID: 35014827 PMCID: PMC9721497 DOI: 10.1021/acsabm.1c00885] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Luminescent silicon nanocrystals are promising nanomaterials for biomedical applications due to their unique optical properties and biocompatibility. Here, we demonstrate a two-step surface modification approach coupling gas-phase and liquid-phase methods to synthesize PEGylated acrylic acid grafted silicon nanocrystals with near-infrared emission in water and biological media. First, acrylic acid grafted silicon nanocrystals are synthesized by an all-gas-phase approach on a millisecond time scale, omitting high temperature and postpurification processes. Subsequently, room-temperature PEGylation is carried out with these acrylic acid grafted silicon nanocrystals, yielding stable colloidal dispersions in both water and high ionic strength Tyrode's buffer with 20-30 nm hydrodynamic diameters. The PEGylated silicon nanocrystals exhibit photoluminescence in the 650-900 nm near-IR window with quantum yields of ∼30% and ∼13% in deionized water and Tyrode's buffer, respectively, after a 7-day oxidation in water. The surface-functionalized Si NCs exhibit relatively small toxicity to MDA-MB-231 cells at concentrations relevant to bioimaging applications.
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Affiliation(s)
- Zhaohan Li
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Advitiya Mahajan
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Himashi P. Andaraarachchi
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yeonjoo Lee
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Uwe R. Kortshagen
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
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8
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Yeh PC, Ohkatsu G, Toyama R, Tue PT, Ostrikov KK, Majima Y, Chiang WH. Towards single electron transistor-based photon detection with microplasma-enabled graphene quantum dots. Nanotechnology 2021; 32:50LT01. [PMID: 34544073 DOI: 10.1088/1361-6528/ac2845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
Single-electron transistors (SETs) represent a new generation of electronic devices with high charge sensitivity, high switching speed, and low power consumption. Here a simple and controlled fabrication of graphene quantum dot (GQD)-based SETs for photon detectors has been demonstrated. The plasma-synthesized GQDs exhibit stable photoluminescence and are successfully used as the Coulomb islands between heteroepitaxial spherical-gold/platinum (HS-Au/Pt) nanogap electrodes. The as-fabricated GQD-SETs enable photon detection with 410 nm excitation owing to the ability of GQDs to generate photoluminescence emission.
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Affiliation(s)
- Pei-Chun Yeh
- Department of Chemical Engineering, National Taiwan University of Science Technology, Taipei 10607, Taiwan
| | - Genki Ohkatsu
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Ryo Toyama
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Phan Trong Tue
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Kostya Ken Ostrikov
- School of Chemistry and Physics and QUT Centre for Materials Science, Queensland University of Technology (QUT), Brisbane, QLD, 4000, Australia
| | - Yutaka Majima
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Wei-Hung Chiang
- Department of Chemical Engineering, National Taiwan University of Science Technology, Taipei 10607, Taiwan
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9
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Abstract
In this paper, a review of cold plasma setups and the physical and chemical processes leading to the generation of active species is presented. The emphasis is given to the interaction of cold plasmas with materials used in medical applications, especially medical implants as well as live cells. An overview of the different kinds of plasmas and techniques used for generation of active species, which significantly alter the surface properties of biomaterials is presented. The elemental processes responsible for the observed changes in the physio-chemical properties of surfaces when exposed to plasma are described. Examples of ongoing research in the field are given to illustrate the state-of-the-art at the more conceptual level.
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Affiliation(s)
| | - Ita Junkar
- Department for Surface Engineering, Jožef Stefan Institute Jamova cesta 39, 1000 Ljubljana, Slovenia;
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10
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Nicolaou G, Livadiotis G. Statistical Uncertainties of Space Plasma Properties Described by Kappa Distributions. Entropy (Basel) 2020; 22:E541. [PMID: 33286313 DOI: 10.3390/e22050541] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/10/2020] [Accepted: 05/11/2020] [Indexed: 11/17/2022]
Abstract
The velocities of space plasma particles often follow kappa distribution functions, which have characteristic high energy tails. The tails of these distributions are associated with low particle flux and, therefore, it is challenging to precisely resolve them in plasma measurements. On the other hand, the accurate determination of kappa distribution functions within a broad range of energies is crucial for the understanding of physical mechanisms. Standard analyses of the plasma observations determine the plasma bulk parameters from the statistical moments of the underlined distribution. It is important, however, to also quantify the uncertainties of the derived plasma bulk parameters, which determine the confidence level of scientific conclusions. We investigate the determination of the plasma bulk parameters from observations by an ideal electrostatic analyzer. We derive simple formulas to estimate the statistical uncertainties of the calculated bulk parameters. We then use the forward modelling method to simulate plasma observations by a typical top-hat electrostatic analyzer. We analyze the simulated observations in order to derive the plasma bulk parameters and their uncertainties. Our simulations validate our simplified formulas. We further examine the statistical errors of the plasma bulk parameters for several shapes of the plasma velocity distribution function.
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11
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López RA, Shaaban SM, Lazar M, Poedts S, Yoon PH, Micera A, Lapenta G. Particle-in-cell Simulations of the Whistler Heat-flux Instability in Solar Wind Conditions. Astrophys J Lett 2019; 882:10.3847/2041-8213/ab398b. [PMID: 32042401 PMCID: PMC7008930 DOI: 10.3847/2041-8213/ab398b] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In collision-poor plasmas from space, e.g., solar wind or stellar outflows, the heat flux carried by the strahl or beaming electrons is expected to be regulated by the self-generated instabilities. Recently, simultaneous field and particle observations have indeed revealed enhanced whistler-like fluctuations in the presence of counter-beaming populations of electrons, connecting these fluctuations to the whistler heat-flux instability (WHFI). This instability is predicted only for limited conditions of electron beam-plasmas, and has not yet been captured in numerical simulations. In this Letter we report the first simulations of WHFI in particle-in-cell setups, realistic for the solar wind conditions, and without temperature gradients or anisotropies to trigger the instability in the initiation phase. The velocity distributions have a complex reaction to the enhanced whistler fluctuations conditioning the instability saturation by a decrease of the relative drifts combined with induced (effective) temperature anisotropies (heating the core electrons and pitch-angle and energy scattering the strahl). These results are in good agreement with a recent quasilinear approach, and support therefore a largely accepted belief that WHFI saturates at moderate amplitudes. In the anti-sunward direction the strahl becomes skewed with a pitch-angle distribution decreasing in width as electron energy increases, which seems to be characteristic of self-generated whistlers and not to small-scale turbulence.
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Affiliation(s)
- R A López
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
| | - S M Shaaban
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
- Theoretical Physics Research Group, Physics Department, Faculty of Science, Mansoura University, 35516, Mansoura, Egypt
| | - M Lazar
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
- Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - S Poedts
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
| | - P H Yoon
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA
- School of Space Research, Kyung Hee University, Republic of Korea
- Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea
| | - A Micera
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
- Solar-Terrestrial Centre of Excellence-SIDC, Royal Observatory of Belgium, B-1180 Brussels, Belgium
| | - G Lapenta
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
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12
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Wilson LB, Chen LJ, Wang S, Schwartz SJ, Turner DL, Stevens ML, Kasper JC, Osmane A, Caprioli D, Bale SD, Pulupa MP, Salem CS, Goodrich KA. Electron Energy Partition across Interplanetary Shocks. I. Methodology and Data Product. Astrophys J Suppl Ser 2019; 243:10.3847/1538-4365/ab22bd. [PMID: 31806920 PMCID: PMC6894189 DOI: 10.3847/1538-4365/ab22bd] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Analyses of 15,314 electron velocity distribution functions (VDFs) within ±2 hr of 52 interplanetary (IP) shocks observed by the Wind spacecraft near 1 au are introduced. The electron VDFs are fit to the sum of three model functions for the cold dense core, hot tenuous halo, and field-aligned beam/strahl component. The best results were found by modeling the core as either a bi-kappa or a symmetric (or asymmetric) bi-self-similar VDF, while both the halo and beam/strahl components were best fit to bi-kappa VDF. This is the first statistical study to show that the core electron distribution is better fit to a self-similar VDF than a bi-Maxwellian under all conditions. The self-similar distribution deviation from a Maxwellian is a measure of inelasticity in particle scattering from waves and/or turbulence. The ranges of values defined by the lower and upper quartiles for the kappa exponents are κ ec ~ 5.40-10.2 for the core, κ eh ~ 3.58-5.34 for the halo, and κ eb ~ 3.40-5.16 for the beam/strahl. The lower-to-upper quartile range of symmetric bi-self-similar core exponents is s ec ~ 2.00-2.04, and those of asymmetric bi-self-similar core exponents are p ec ~ 2.20-4.00 for the parallel exponent and q ec ~ 2.00-2.46 for the perpendicular exponent. The nuanced details of the fit procedure and description of resulting data product are also presented. The statistics and detailed analysis of the results are presented in Paper II and Paper III of this three-part study.
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Affiliation(s)
- Lynn B Wilson
- NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, USA
| | - Li-Jen Chen
- NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, USA
| | - Shan Wang
- NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, USA
- Astronomy Department, University of Maryland, College Park, Maryland, USA
| | - Steven J Schwartz
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Boulder, CO, USA
| | - Drew L Turner
- Space Sciences Department, The Aerospace Corporation, El Segundo, CA, USA
| | - Michael L Stevens
- Harvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, MA, USA
| | - Justin C Kasper
- University of Michigan, Ann Arbor, School of Climate and Space Sciences and Engineering, Ann Arbor, MI, USA
| | - Adnane Osmane
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Damiano Caprioli
- Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA
| | - Stuart D Bale
- University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, USA
| | - Marc P Pulupa
- University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, USA
| | - Chadi S Salem
- University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, USA
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13
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Kempski P, Quataert E, Squire J, Kunz MW. Shearing-box simulations of MRI-driven turbulence in weakly collisional accretion discs. Mon Not R Astron Soc 2019; 486:4013-4029. [PMID: 35136273 PMCID: PMC8819626 DOI: 10.1093/mnras/stz1111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We present a systematic shearing-box investigation of MRI-driven turbulence in a weakly collisional plasma by including the effects of an anisotropic pressure stress, i.e. anisotropic (Braginskii) viscosity. We constrain the pressure anisotropy (Δp) to lie within the stability bounds that would be otherwise imposed by kinetic microinstabilities. We explore a broad region of parameter space by considering different Reynolds numbers and magnetic-field configurations, including net vertical flux, net toroidal-vertical flux and zero net flux. Remarkably, we find that the level of turbulence and angular-momentum transport are not greatly affected by large anisotropic viscosities: the Maxwell and Reynolds stresses do not differ much from the MHD result. Angular-momentum transport in Braginskii MHD still depends strongly on isotropic dissipation, e.g., the isotropic magnetic Prandtl number, even when the anisotropic viscosity is orders of magnitude larger than the isotropic diffusivities. Braginskii viscosity nevertheless changes the flow structure, rearranging the turbulence to largely counter the parallel rate of strain from the background shear. We also show that the volume-averaged pressure anisotropy and anisotropic viscous transport decrease with increasing isotropic Reynolds number (Re); e.g., in simulations with net vertical field, the ratio of anisotropic to Maxwell stress (α A/α M) decreases from ~ 0.5 to ~ 0.1 as we move from Re ~ 103 to Re ~ 104, while 〈4πΔp/B 2〉 → 0. Anisotropic transport may thus become negligible at high Re. Anisotropic viscosity nevertheless becomes the dominant source of heating at large Re, accounting for ≳50% of the plasma heating. We conclude by briefly discussing the implications of our results for RIAFs onto black holes.
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Affiliation(s)
- Philipp Kempski
- Department of Astronomy and Theoretical Astrophysics Center, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Eliot Quataert
- Department of Astronomy and Theoretical Astrophysics Center, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jonathan Squire
- Department of Physics, University of Otago, 730 Cumberland St, North Dunedin, Dunedin 9016, New Zealand
| | - Matthew W. Kunz
- Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, New Jersey 08544, USA
- Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543, USA
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14
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Bérard R, Makasheva K, Sabbah H, Demyk K, Joblin C. Using cold plasma to investigate the mechanisms involved in cosmic dust formation: role of the C/O ratio and metals. ACTA ACUST UNITED AC 2019; 15:397-00. [PMID: 33072172 DOI: 10.1017/S1743921319008457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Using a cold plasma reactor in which we inject an organosilicon molecular precursor, we investigate chemical mechanisms that can be involved in dust formation in evolved stars. By injecting metal atoms into the gas-phase, we investigate the role of metals on dust composition. We show the formation of composite particles made of pure metal (silver) nanoparticles embedded in an organosilicon dust. We study the impact of oxygen and show that it can inhibit dust formation, likely through the destruction of nucleation seeds.
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15
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Sun H, Xi P, Sun Z, Wang Q, Zhu B, Zhou J, Jin H, Zheng W, Tang W, Cao H, Cao X. Circ-SFMBT2 promotes the proliferation of gastric cancer cells through sponging miR-182-5p to enhance CREB1 expression. Cancer Manag Res 2018; 10:5725-5734. [PMID: 30510446 PMCID: PMC6248399 DOI: 10.2147/cmar.s172592] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Background Circular RNAs(circRNAs) have been reported as a diverse class of endogenous RNA that regulate gene expression in eukaryotes. Recent evidence suggested that many circular RNAs can act as oncogenes or tumor suppressors through sponging microRNAs. However, the function of circular RNAs in gastric cancer remains largely unknown. Materials and methods The circRNA levels in gastric carcinoma tissues and plasmas were detected by real-time quantitative reverse transcription-polymerase chain reaction. The correlation between the expression of circRNA and clinic pathological features was analyzed. Rate of inhibiting of proliferation was measured using a CCK-8 cell proliferation assay. Clone formation ability was assessed with a clone formation inhibition test. We used the bioinformatics software to predict circRNA-miRNA and miRNA-mRNA interactions. Relative gene expression was assessed using quantitative real-time polymerase chain reaction and relative protein expression levels were determined with western blotting. CircRNA and miRNA interaction was confirmed by dual-luciferase reporter assays. Results We characterized that one circRNA named circ-SFMBT2 showed an increased expression level in gastric cancer tissues compared to adjacent non-cancerous tissues and was associated with higher tumor stages of gastric cancer. Silencing of circ-SFMBT2 inhibited the proliferation of gastric cancer cells significantly. Importantly, we demonstrated that circ-SFMBT2 could act as a sponge of miR-182-5p to regulate the expression of CREB1 mRNA, named as cAMP response element binding protein 1, and further promote the proliferation of gastric cancer cells. Conclusion Our study reveals that circ-SFMBT2 participates in progression of gastric cancer by competitively sharing miR-182-5p with CREB1, providing a novel target to improve the treatment of gastric cancer. mutation-analysis-of-beta-thalassemia-in-east-western-indian-populatio-peer-reviewed-article-TACG for an example.
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Affiliation(s)
- Handong Sun
- Department of Oncology Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, China,
| | - Pengcheng Xi
- Department of General Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China,
| | - Zhiqiang Sun
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China.,Department of Stem Cells and Regenerative Medicine, Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Peking Union Medical College, Tianjin, China
| | - Qian Wang
- Department of Oncology Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, China,
| | - Bin Zhu
- Department of Oncology Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, China,
| | - Jian Zhou
- Department of Oncology Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, China,
| | - Hui Jin
- Department of Hematology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China.,Key Laboratory of Hematology of Nanjing Medical University, Nanjing, China
| | - Wubin Zheng
- Department of General Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China,
| | - Weiwei Tang
- Department of General Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China,
| | - Hongyong Cao
- Department of General Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China,
| | - Xiufeng Cao
- Department of Oncology Surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, China, .,Department of Thoracic Surgery, Taikang Xianlin Drum Tower Hospital, School of Medicine, Nanjing University, Nanjing, China,
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16
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Cohen O, Moschou SP, Glocer A, Sokolov IV, Mazeh T, Drake JJ, Garraffo C, Alvarado-GÓmez JD. EXOPLANET MODULATION OF STELLAR CORONAL RADIO EMISSION. Astron J 2018; 156:202. [PMID: 33510541 PMCID: PMC7839303 DOI: 10.3847/1538-3881/aae1f2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The search for exoplanets in the radio bands has been focused on detecting radio emissions produced by the interaction between magnetized planets and the stellar wind (auroral emission). Here we introduce a new tool, which is part of our MHD stellar corona model, to predict the ambient coronal radio emission and its modulations induced by a close planet. For simplicity, the present work assumes that the exoplanet is stationary in the frame rotating with the stellar rotation. We explore the radio flux modulations using a limited parameter space of idealized cases by changing the magnitude of the planetary field, its polarity, the planetary orbital separation, and the strength of the stellar field. We find that the modulations induced by the planet could be significant and observable in the case of hot Jupiter planets - above 100% modulation with respect to the ambient flux in the 10 - 100 MHz range in some cases, and 2-10% in the frequency bands above 250 MHz for some cases. Thus, our work indicates that radio signature of exoplanets might not be limited to low-frequency radio range. We find that the intensity modulations are sensitive to the planetary magnetic field polarity for short-orbit planets, and to the stellar magnetic field strength for all cases. The new radio tool, when applied to real systems, could provide predictions for the frequency range at which the modulations can be observed by current facilities.
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Affiliation(s)
- Offr Cohen
- Lowell Center for Space Science and Technology, University of Massachusetts Lowell 600 Suffolk St., Lowell, MA 01854, USA
| | | | - Alex Glocer
- NASA/Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Igor V Sokolov
- Center for Space Environment Modeling, University of Michigan, 2455 Hayward, Ann Arbor, Michigan USA
| | - Tsevi Mazeh
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jeremy J Drake
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts, USA
| | - C Garraffo
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts, USA
| | - J D Alvarado-GÓmez
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts, USA
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17
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Kajita S, Mimuro F, Yoshida T, Ohno N, Yoshida N. One-Step Plasma Synthesis of Nb 2 O 5 Nanofibers and their Enhanced Photocatalytic activity. Chemphyschem 2018; 19:3237-3246. [PMID: 30251462 DOI: 10.1002/cphc.201800769] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Indexed: 11/08/2022]
Abstract
Fiberform nanostructured niobium (Nb) was fabricated by one step helium (He) plasma irradiation. He ion implantation formed He nano-bubbles on a Nb plate and led to formation of protrusions while migrating in Nb matrix; fiberform nanostructures (FN) were grown when the fluence became high (>1026 m-2 ). The necessary conditions for the formation of Nb FN were revealed to be the surface temperature range of 900-1100 K and the incident ion energy higher than 70 eV. The sample was oxidized at 573-773 K in an air atmosphere, and Pt nanoparticles were photo-deposited on the Nb2 O5 samples. The surface was analyzed by scanning electron microscope, transmission electron microscope, x-ray photoelectron spectroscopy, and ultraviolet-visible spectrophotometry. Photocatalytic activity of the fabricated materials was studied using methylene blue (MB) decolorization process. An enhanced photocatalytic performance was identified on FN Nb2 O5 substrate with Pt deposition.
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Affiliation(s)
- Shin Kajita
- Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya, 464-8603, Japan
| | - Fumiaki Mimuro
- Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8603, Japan
| | - Tomoko Yoshida
- The Osaka City University, Advanced Research Institute for Natural Science and Technology, Sumiyoshi, Sugimoto-cho, 3-3-138, Osaka, 558-8585, Japan
| | - Noriyasu Ohno
- Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8603, Japan
| | - Naoaki Yoshida
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan
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18
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Abstract
We present a method to quantify the upper-limit of the energy transmitted from the intense stellar wind to the upper atmospheres of three of the Trappist-1 planets (e, f, and g). We use a formalism that treats the system as two electromagnetic regions, where the efficiency of the energy transmission between one region (the stellar wind at the planetary orbits) to the other (the planetary ionospheres) depends on the relation between the conductances and impedances of the two regions. Since the energy flux of the stellar wind is very high at these planetary orbits, we find that for the case of high transmission efficiency (when the conductances and impedances are close in magnitude), the energy dissipation in the upper planetary atmospheres is also very large. On average, the Ohmic energy can reach 0.5 - 1 W/m 2, about 1% of the stellar irradiance and 5-15 times the EUV irradiance. Here, using constant values for the ionospheric conductance, we demonstrate that the stellar wind energy could potentially drive large atmospheric heating in terrestrial planets, as well as in hot jupiters. More detailed calculations are needed to assess the ionospheric conductance and to determine more accurately the amount of heating the stellar wind can drive in close-orbit planets.
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Affiliation(s)
- Ofer Cohen
- Lowell Center for Space Science and Technology, University of Massachusetts Lowell 600 Suffolk St., Lowell, MA 01854, USA
- Harvard-Smithsonian Center for Astrophysics,60 Garden St., Cambridge, MA 02138, USA
| | - Alex Glocer
- NASA/Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Cecilia Garraffo
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts, USA
| | - Jeremy J Drake
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts, USA
| | - Jared M Bell
- National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666, USA
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19
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Abstract
Previous modeling studies of Titan's dayside ionosphere predict electron number densities that are roughly a factor of 2 higher than those observed by the RPWS/Langmuir probe. The issue can equivalently be described as the ratio between the calculated electron production rates and the square of the observed electron number densities resulting in roughly a factor of 4 higher effective recombination coefficient than expected from the ion composition and the electron temperature. Here we make an extended reassessment of Titan's dayside ionization balance, focusing on 34 flybys between TA and T120. Using a recalibrated data set and by taking the presence of negative ions into account, we arrive at lower effective recombination coefficients compared with earlier studies. The values are still higher than expected from the ion composition and the electron temperature, but by a factor of ~2-3 instead of a factor of ~4. We have also investigated whether the derived effective recombination coefficients display dependencies on the solar zenith angle (SZA), the integrated solar EUV intensity (<80 nm), and the corotational plasma ram direction (RAM), and found statistically significant trends, which may be explained by a declining photoionization against the background ionization by magnetospheric particles (trends in SZA and RAM) and altered photochemistry (trend in EUV). We find that a series of flybys that occurred during solar minimum (2008) and with similar flyby geometries are associated with enhanced values of the effective recombination coefficient compared with the remaining data set, which also suggests a chemistry dependence on the sunlight conditions.
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Affiliation(s)
- O Shebanits
- Swedish Institute of Space Physics, Uppsala, Sweden
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - E Vigren
- Swedish Institute of Space Physics, Uppsala, Sweden
| | - J-E Wahlund
- Swedish Institute of Space Physics, Uppsala, Sweden
| | - N J T Edberg
- Swedish Institute of Space Physics, Uppsala, Sweden
| | - J Cui
- School of Atmospheric Sciences, Sun Yat-Sen University, Zhuhai, Guangdong, China
| | - K E Mandt
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, USA
| | - J H Waite
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, USA
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20
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Ghosh S, Polaki SR, Kumar N, Amirthapandian S, Kamruddin M, Ostrikov K(K. Process-specific mechanisms of vertically oriented graphene growth in plasmas. Beilstein J Nanotechnol 2017; 8:1658-1670. [PMID: 28875103 PMCID: PMC5564255 DOI: 10.3762/bjnano.8.166] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 07/25/2017] [Indexed: 05/26/2023]
Abstract
Applications of plasma-produced vertically oriented graphene nanosheets (VGNs) rely on their unique structure and morphology, which can be tuned by the process parameters to understand the growth mechanism. Here, we report on the effect of the key process parameters such as deposition temperature, discharge power and distance from plasma source to substrate on the catalyst-free growth of VGNs in microwave plasmas. A direct evidence for the initiation of vertical growth through nanoscale graphitic islands is obtained from the temperature-dependent growth rates where the activation energy is found to be as low as 0.57 eV. It is shown that the growth rate and the structural quality of the films could be enhanced by (a) increasing the substrate temperature, (b) decreasing the distance between the microwave plasma source and the substrate, and (c) increasing the discharge power. The correlation between the wetting characteristics, morphology and structural quality is established. It is also demonstrated that morphology, crystallinity, wettability and sheet resistance of the VGNs can be varied while maintaining the same sp3 content in the film. The effects of the substrate temperature and the electric field in vertical alignment of the graphene sheets are reported. These findings help to develop and optimize the process conditions to produce VGNs tailored for applications including sensing, field emission, catalysis and energy storage.
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Affiliation(s)
- Subrata Ghosh
- Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research - Homi Bhabha National Institute, Kalpakkam - 603102, India
| | - Shyamal R Polaki
- Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research - Homi Bhabha National Institute, Kalpakkam - 603102, India
| | - Niranjan Kumar
- Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research - Homi Bhabha National Institute, Kalpakkam - 603102, India
| | - Sankarakumar Amirthapandian
- Materials Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research - Homi Bhabha National Institute, Kalpakkam - 603102, India
| | - Mohamed Kamruddin
- Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research - Homi Bhabha National Institute, Kalpakkam - 603102, India
| | - Kostya (Ken) Ostrikov
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane QLD 4000, Australia
- CSIRO-QUT Joint Sustainable Processes and Devices Laboratory, Lindfield NSW 2070, Australia
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21
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Maguire P, Rutherford D, Macias-Montero M, Mahony C, Kelsey C, Tweedie M, Pérez-Martin F, McQuaid H, Diver D, Mariotti D. Continuous In-Flight Synthesis for On-Demand Delivery of Ligand-Free Colloidal Gold Nanoparticles. Nano Lett 2017; 17:1336-1343. [PMID: 28139927 DOI: 10.1021/acs.nanolett.6b03440] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate an entirely new method of nanoparticle chemical synthesis based on liquid droplet irradiation with ultralow (<0.1 eV) energy electrons. While nanoparticle formation via high energy radiolysis or transmission electron microscopy-based electron bombardment is well-understood, we have developed a source of electrons with energies close to thermal which leads to a number of important and unique benefits. The charged species, including the growing nanoparticles, are held in an ultrathin surface reaction zone which enables extremely rapid precursor reduction. In a proof-of-principle demonstration, we obtain small-diameter Au nanoparticles (∼4 nm) with tight control of polydispersity, in under 150 μs. The precursor was almost completely reduced in this period, and the resultant nanoparticles were water-soluble and free of surfactant or additional ligand chemistry. Nanoparticle synthesis rates within the droplets were many orders of magnitude greater than equivalent rates reported for radiolysis, electron beam irradiation, or colloidal chemical synthesis where reaction times vary from seconds to hours. In our device, a stream of precursor loaded microdroplets, ∼15 μm in diameter, were transported rapidly through a cold atmospheric pressure plasma with a high charge concentration. A high electron flux, electron and nanoparticle confinement at the surface of the droplet, and the picoliter reactor volume are thought to be responsible for the remarkable enhancement in nanoparticle synthesis rates. While this approach exhibits considerable potential for scale-up of synthesis rates, it also offers the more immediate prospect of continuous on-demand delivery of high-quality nanomaterials directly to their point of use by avoiding the necessity of collection, recovery, and purification. A range of new applications can be envisaged, from theranostics and biomedical imaging in tissue to inline catalyst production for pollution remediation in automobiles.
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Affiliation(s)
- Paul Maguire
- NIBEC, University of Ulster , Belfast, BT37 0QB, Northern Ireland
| | - David Rutherford
- NIBEC, University of Ulster , Belfast, BT37 0QB, Northern Ireland
| | | | - Charles Mahony
- NIBEC, University of Ulster , Belfast, BT37 0QB, Northern Ireland
| | - Colin Kelsey
- NIBEC, University of Ulster , Belfast, BT37 0QB, Northern Ireland
| | - Mark Tweedie
- NIBEC, University of Ulster , Belfast, BT37 0QB, Northern Ireland
| | | | - Harold McQuaid
- NIBEC, University of Ulster , Belfast, BT37 0QB, Northern Ireland
| | - Declan Diver
- SUPA, School of Physics and Astronomy, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Davide Mariotti
- NIBEC, University of Ulster , Belfast, BT37 0QB, Northern Ireland
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Bartschat K, Kushner MJ. Electron collisions with atoms, ions, molecules, and surfaces: Fundamental science empowering advances in technology. Proc Natl Acad Sci U S A 2016; 113:7026-34. [PMID: 27317740 DOI: 10.1073/pnas.1606132113] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electron collisions with atoms, ions, molecules, and surfaces are critically important to the understanding and modeling of low-temperature plasmas (LTPs), and so in the development of technologies based on LTPs. Recent progress in obtaining experimental benchmark data and the development of highly sophisticated computational methods is highlighted. With the cesium-based diode-pumped alkali laser and remote plasma etching of Si3N4 as examples, we demonstrate how accurate and comprehensive datasets for electron collisions enable complex modeling of plasma-using technologies that empower our high-technology-based society.
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Cowley SC, Cowley B, Henneberg SA, Wilson HR. Explosive instability and erupting flux tubes in a magnetized plasma. Proc Math Phys Eng Sci 2015; 471:20140913. [PMID: 26339193 DOI: 10.1098/rspa.2014.0913] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 07/07/2015] [Indexed: 11/12/2022] Open
Abstract
The eruption of multiple flux tubes in a magnetized plasma is proposed as a mechanism for explosive release of energy in plasmas. A significant fraction of the linearly stable isolated flux tubes are shown to be metastable in a box model magnetized atmosphere in which ends of the field lines are embedded in conducting walls. The energy released by destabilizing such field lines can be a large proportion of the gravitational energy stored in the system. This energy can be released in a fast dynamical time.
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Affiliation(s)
- S C Cowley
- CCFE, Culham Science Centre , Abingdon, Oxon OX14 3DB, UK ; Department of Physics , Imperial College , Prince Consort Road, London SW7 2BZ, UK
| | - B Cowley
- Department of Physics , University College London , London WC1E 6BT, UK
| | - S A Henneberg
- York Plasma Institute, Department of Physics , University of York , Heslington, York YO10 5DD, UK
| | - H R Wilson
- York Plasma Institute, Department of Physics , University of York , Heslington, York YO10 5DD, UK
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