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arXiv 2024年

作者： Johnson, Michael D. Akiyama, Kazunori Baturin, Rebecca Bilyeu, Bryan Blackburn, Lindy Boroson, Don Cárdenas-Avendaño, Alejandro Chael, Andrew Chan, Chi-Kwan Chang, Dominic Cheimets, Peter Chou, Cathy Doeleman, Sheperd S. Farah, Joseph Galison, Peter Gamble, Ronald Gammie, Charles F. Gelles, Zachary Gómez, José L. Gralla, Samuel E. Grimes, Paul Gurvits, Leonid I. Hadar, Shahar Haworth, Kari Hada, Kazuhiro Hecht, Michael H. Honma, Mareki Houston, Janice Hudson, Ben Issaoun, Sara Jia, He Jorstad, Svetlana Kauffmann, Jens Kovalev, Yuri Y. Kurczynski, Peter Lafon, Robert Lupsasca, Alexandru Lehmensiek, Robert Ma, Chung-Pei Marrone, Daniel P. Marscher, Alan P. Melnick, Gary J. Narayan, Ramesh Niinuma, Kotaro Noble, Scott C. Palmer, Eric J. Palumbo, Daniel C.M. Paritsky, Lenny Peretz, Eliad Pesce, Dominic Plavin, Alexander Quataert, Eliot Rana, Hannah Ricarte, Angelo Roelofs, Freek Shtyrkova, Katia Sinclair, Laura C. Small, Jeffrey Kumara, Sridharan Tirupati Srinivasan, Ranjani Strominger, Andrew Tiede, Paul Tong, Edward Wang, Jade Weintroub, Jonathan Wielgus, Maciek Wong, George Zhang, Xinyue Alice Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Black Hole Initiative Harvard University 20 Garden Street CambridgeMA02138 United States Haystack Observatory Massachusetts Institute of Technology WestfordMA01886 United States Mizusawa VLBI Observatory National Astronomical Observatory of Japan Iwate023-0861 Japan MIT Lincoln Laboratory LexingtonMA02421 United States Princeton Gravity Initiative Princeton University PrincetonNJ08544 United States Steward Observatory and Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States Las Cumbres Observatory 6740 Cortona Drive GoletaCA93117-5575 United States Department of Physics University of California Santa BarbaraCA93106-9530 United States Department of History of Science Harvard University CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States NASA Goddard Space Flight Center GreenbeltMD20771 United States Departments of Astronomy and of Physics University of Illinois UrbanaIL61801 United States Instituto de Astrofísica de Andalucía CSIC Glorieta de la Astronomía s/n GranadaE-18008 Spain Department of Physics University of Arizona TucsonAZ85719 United States Joint Institute for VLBI ERIC Dwingeloo7991PD Netherlands Faculty of Aerospace Engineering Delft University of Technology Delft2629 HS Netherlands Department of Mathematics and Physics University of Haifa at Oranim Kiryat Tivon3600600 Israel Haifa Research Center for Theoretical Physics and Astrophysics University of Haifa Haifa3498838 Israel 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-

We present the Black Hole Explorer (BHEX), a mission that will produce the sharpest images in the history of astronomy by extending submillimeter Very-Long-Baseline Interferometry (VLBI) to space. BHEX will discover and measure the bright and narrow "photon ring" that is predicted to exist in images of black holes, produced from light that has orbited the black hole before escaping. This discovery will expose universal features of a black hole's spacetime that are distinct from the complex astrophysics of the emitting plasma, allowing the first direct measurements of a supermassive black hole's spin. In addition to studying the properties of the nearby supermassive black holes M87*and Sgr A*, BHEX will measure the properties of dozens of additional supermassive black holes, providing crucial insights into the processes that drive their creation and growth. BHEX will also connect these supermassive black holes to their relativistic jets, elucidating the power source for the brightest and most efficient engines in the universe. BHEX will address fundamental open questions in the physics and astrophysics of black holes that cannot be answered without submillimeter space VLBI. The mission is enabled by recent technological breakthroughs, including the development of ultra-high-speed downlink using laser communications, and it leverages billions of dollars of existing ground infrastructure. We present the motivation for BHEX, its science goals and associated requirements, and the pathway to launch within the next decade. © 2024, CC BY.

关键词： Photons

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Reconstructing positive and negative couplings in Ising spin networks by sorted local transfer entropy

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Physical Review E 2019年第1期100卷 012121-012121页

作者： Felix Goetze Pik-Yin Lai Department of Physics and Center for Complex Systems National Central University Chung-Li District Taoyuan City 320 Taiwan Republic of China and Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei Taiwan Republic of China.

We employ the sorted local transfer entropy (SLTE) to reconstruct the coupling strengths of Ising spin networks with positive and negative couplings (Jij), using only the time-series data of the spins. The SLTE method is model-free in the sense that no knowledge of the underlying dynamics of the spin system is required and is applicable to a broad class of systems. Contrary to the inference of coupling from pairwise transfer entropy, our method can reliably distinguish spin pair interactions with positive and negative couplings. The method is tested for the inverse Ising problem for different Jij distributions and various spin dynamics, including synchronous and asynchronous update Glauber dynamics and Kawasaki exchange dynamics. It is found that the pairwise SLTE is proportional to the pairwise coupling strength to a good extent for all cases studied. In addition, the reconstruction works well for both the equilibrium and nonequilibrium cases of the time-series data. Comparison to other inverse Ising problem approaches using mean-field equations is also discussed.

关键词： Information theory Ising model Time series analysis

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Development of e-learning-based evalution tools for learning energy sources in elementary schools

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Journal of physics: Conference Series 2021年第5期1918卷

作者： Riyanti E Susilaningsih N M D Putra Department of Primary Education Graduate Program Universitas Negeri Semarang Indonesia Department of Chemistry Faculty of Mathematics and Natural Science Universitas Negeri Semarang Indonesia Department of Physics Faculty of Mathematics and Natural Science Universitas Negeri Semarang Indonesia

This study aims to develop an e-learning-based evaluation tool to assist teachers and students in distance learning activities about energy sources in elementary schools. Preliminaries conducted by researchers in ten elementary schools in Cirebon Regency show that teachers find it difficult to evaluate students so that the results obtained have not reached 75% complete classical. The type of used research is research and development (R&D) with a 4-D model consisting of 4 stages, namely define, design, development, and dissemination. This study used a group pretest-posttest design. The research subjects were 58 students of SD Negeri 3 Panembahan Cirebon Regency. The data collection instruments were carried out with interview sheets, tests and questionnaires. Quantitative data analysis techniques with parametric statistics, t-test one sample spss, Z proportion test. The results showed that the e-learning based evaluation tool using hosting and the developed domain was feasible, namely 3.82 with an average total score of 4.00 very valid category. Teacher response obtained 97.14% (very good). Student response obtained 98.42% (very good). Students experience classical completeness by 89%. It can be concluded that the use of e-learning based evaluation tools is a solution to the faced problems by teachers and students today as an alternative in assisting the implementation of distance learning.

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The structural, vibrational, and mechanical properties of jammed packings of deformable particles in three dimensions

arXiv

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arXiv 2021年

作者： Wang, Dong Treado, John D. Boromand, Arman Norwick, Blake Murrell, Michael P. Shattuck, Mark D. O'Hern, Corey S. Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Biomedical Engineering Yale University New HavenCT06520 United States Systems Biology Institute Yale University West HavenCT06516 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Applied Physics Yale University New HavenCT06520 United States

We investigate the structural, vibrational, and mechanical properties of jammed packings of deformable particles with shape degrees of freedom in three dimensions (3D). Each 3D deformable particle is modeled as a surface-triangulated polyhedron, with spherical vertices whose positions are determined by a shape-energy function with terms that constrain the particle surface area, volume, and curvature, and prevent interparticle overlap. We show that jammed packings of deformable particles without bending energy possess low-frequency, quartic vibrational modes, whose number decreases with increasing asphericity and matches the number of missing contacts relative to the isostatic value. In contrast, jammed packings of deformable particles with non-zero bending energy are isostatic in 3D, with no quartic modes. We find that the contributions to the eigenmodes of the dynamical matrix from the shape degrees of freedom are significant over the full range of frequency and shape parameters for particles with zero bending energy. We further show that the ensembleaveraged shear modulus hGi scales with pressure P as hGi ∼ pβ, with β ≈ 0.75 for jammed packings of deformable particles with zero bending energy. In contrast, β ≈ 0.5 for packings of deformable particles with non-zero bending energy, which matches the value for jammed packings of soft, spherical particles with fixed shape. These studies underscore the importance of incorporating particle deformability and shape change when modeling the properties of jammed soft materials. © 2021, CC BY.

关键词： Degrees of freedom (mechanics)

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The SRG/eROSITA All-Sky Survey. The Weak-Lensing Mass Calibration and the Stellar Mass-to-Halo Mass Relation from the Hyper Suprime-Cam Subaru Strategic program

arXiv

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arXiv 2025年

作者： Chiu, I-Non Ghirardini, Vittorio Grandis, Sebastian Okabe, Nobuhiro Bulbul, Esra Bahar, Emre Y. Balzer, Fabian Clerc, Nicolas Comparat, Johan Kleinebreil, Florian Kluge, Matthias Liu, Ang Monteiro-Oliveira, Rogério Oguri, Masamune Pacaud, Florian Ceja, Miriam Ramos Reiprich, Thomas H. Sanders, Jeremy Schrabback, Tim Seppi, Riccardo Sommer, Martin Tam, Sut-Ieng Umetsu, Keiichi Zhang, Xiaoyuan Department of Physics National Cheng Kung University No.1 University Road Tainan City70101 Taiwan Max Planck Institute for Extraterrestrial Physics Giessenbachstrasse 1 Garching85748 Germany Universität Innsbruck Institut für Astro- und Teilchenphysik Technikerstr. 25/8 Innsbruck6020 Austria Physics Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Hiroshima Astrophysical Science Center Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Core Research for Energetic Universe Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan IRAP Université de Toulouse CNRS UPS CNES Toulouse France Institute of Astronomy and Astrophysics Academia Sinica P.O. Box 23-141 Taipei10617 Taiwan Center for Frontier Science Chiba University 1-33 Yayoi-cho Inage-ku Chiba263-8522 Japan Department of Physics Graduate School of Science Chiba University 1-33 Yayoi-Cho Inage-Ku Chiba263-8522 Japan Universität Bonn Auf dem Hügel 71 Bonn53121 Germany Institute of Physics National Yang Ming Chiao Tung University 1001 University Road Hsinchu30010 Taiwan

We present the weak-lensing mass calibration of 124 galaxy clusters and groups at redshift 0.1 ✶,BCG–M–z) relation, using the data sets from the Hyper Suprime-Cam (HSC) Subaru Strategic program. The cluster survey is conducted by the eROSITA X-ray telescope aboard the Spectrum-Roentgen-Gamma (SRG) space observatory. The cluster sample is X-ray-selected and optically confirmed with a negligibly low contamination rate (≈ 5%). On a basis of individual clusters, the shear profiles g+ of 96 clusters are derived using the HSC Three-Year (HSCY3) weak-lensing data, while the BCG stellar masses M✶,BCG of 101 clusters are estimated using the SED template fitting to the HSC five-band (grizY) photometry. The observed X-ray photon count rate CR is used as the mass proxy, based on which individual halo masses M are obtained while accounting for systematic uncertainties in the weak-lensing modelling through a simulation-calibrated weak-lensing mass-to-halo-mass (MWL–M–z) relation. The count rate (CR–M–z) and BCG stellar mass (M✶,BCG–M–z) relations are simultaneously constrained in a forward and population modelling. In agreement with the results based on the weak-lensing data from the DES and KiDS surveys, the CR–M–z relation reveals a mass trend of (formula presented) , which is steeper than the self-similar prediction, and no deviation from the self-similar redshift scaling. We obtain the power-law indices BBCG and γBCG of the mass (BBCG = 0.25+0.11−0.15) and redshift (γBCG = 0.87+0.92−0.78) scaling for the M✶,BCG–M–z relation, respectively, and find a strong degeneracy between them. By adopting an informative prior on γBCG to break the BBCG–γBCG degeneracy, we obtain a statistically consistent M✶,BCG–M–z relation, with the mass slope increasing to BBCG = 0.39 ± 0.11. Informed by the prior, our results suggest that the BCG stellar mass at a fixed halo mass has remained stable with a moderate increase at a level of (20 ± 8) % since redshift z ≈ 0.8. This finding supports the pict

关键词： Dark Matter

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Polystyrene foam-based pipette-tip Micro-solid phase extraction (PFPT-μSPE) using Ni-MOF@S-CQDs nanocomposite: A novel method for efficient extraction of Lead from water and food samples

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Food chemistry 2025年 490卷 145101页

作者： Mustafa Soylak Sabrina Sajjad Qamar Salamat Hassan Elzain Hassan Ahmed Erciyes University Faculty of Sciences Department of Chemistry 38039 Kayseri Türkiye Technology Research and Application Center (ERU-TAUM) Erciyes University 38039 Kayseri Türkiye Turkish Academy of Sciences (TUBA) Çankaya Ankara Türkiye. Electronic address: soylak@erciyes.edu.tr. Erciyes University Graduate School of Natural and Applied Sciences Chemistry Graduate Program Kayseri Türkiye. Erciyes University Faculty of Sciences Department of Chemistry 38039 Kayseri Türkiye. Sudan Atomic Energy Commission (SAEC) - Chemistry and Nuclear Physics Institute Khartoum Sudan Sudan University of Science and Technology (SUST) - College of Science-Scientific Laboratories Department Chemistry Section Khartoum Sudan.

A novel Ni-MOF@S-CQDs nanocomposite was synthesized directly into the pores of a polystyrene foam. It was characterized using FTIR, XRD, SEM, and SEM-EDX techniques. The adsorbent was effectively applied for the extraction of Pb (II) from water, juice, and iced tea samples, followed by analysis using UV-VIS spectrometry. Various analytical factors, including pH, adsorbent amount, adsorption and desorption times, and sample volume, were studied. Under the optimum conditions, the analytical features were obtained; the LDR of 50-5000 μg L, the LOD of 15 μg L, and the RSDs% of 2.0 and 4.0 for intra-day and inter-day, respectively. The preconcentration (PF) and the enrichment (EF) factors of 30, the factor of 28.5, and the extraction efficiency (EE) of 95 % were obtained. Certified reference materials (CRMs) were used to validate the novel Polystyrene Foam-Pipette Tip Micro-Solid Phase Extraction (PFPT-μSPE) technique. This study is eco-friendly, accurate, and economical for the extraction of Pb (II) from water and beverage samples.

关键词： Carbon quantum dot Iced tea Lead Ni-MOF Solid-phase extraction

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THz Generation Control in Fe/X Spintronic Multilayers by chemical bonding at epitaxial Fe/GaAs(001) interfaces

THz Generation Control in Fe/X Spintronic Multilayers by che...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Roman Adam Genyu Chen Daniel E. Bürgler Derang Cao Sarah Heidtfeld Debamitra Chakraborty Jing Cheng Ivan Komissarov Hilde Hardtdegen Martin Mikulics Claus M. Schneider Roman Sobolewski Research Centre Jülich Peter Grünberg Institute (PGI-6) Jülich Germany Materials Science Graduate Program University of Rochester Rochester New York USA Laboratory for Laser Energetics University of Rochester Rochester New York USA College of Physics Center for Marine Observation and Communications Qingdao University Qingdao China Department of Electrical and Computer Engineering University of Rochester Rochester New York USA Research Centre Jülich Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons Jülich Germany Department of Physics University of California Davis Davis California USA

We report an additional degree of control of THz transients in Fe/X spintronic emitters grown on GaAs(001). We ascribe the field-independent enhancement of the THz amplitude to specific chemical bonding at the epitaxi... 详细信息

ISBN: (纸本)9781943580910

关键词： Electromagnetic radiation Free electron lasers Gallium arsenide Magnetic fields Terahertz generation Ultrafast lasers

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MAGIC observations of HESS J1809-193 using the Very Large Zenith Angle technique at energies above TeV 37

MAGIC observations of HESS J1809-193 using the Very Large Ze...

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37th International Cosmic Ray Conference, ICRC 2021

作者： Acciari, V.A. Ansoldi, S. Antonelli, L.A. Arbet Engels, A. Artero, M. Asano, K. Baack, D. Babić, A. Baquero, A. Barres de Almeida, U. Barrio, J.A. Batković, I. Becerra González, J. Bednarek, W. Bellizzi, L. Bernardini, E. Bernardos, M. Berti, A. Besenrieder, J. Bhattacharyya, W. Bigongiari, C. Biland, A. Blanch, O. Bökenkamp, H. Bonnoli, G. Bošnjak, Ž. Busetto, G. Carosi, R. Ceribella, G. Cerruti, M. Chai, Y. Chilingarian, A. Cikota, S. Colak, S.M. Colombo, E. Contreras, J.L. Cortina, J. Covino, S. D'Amico, G. D'Elia, V. Da Vela, P. Dazzi, F. De Angelis, A. De Lotto, B. Delfino, M. Delgado, J. Delgado Mendez, C. Depaoli, D. Di Pierro, F. Di Venere, L. Do Souto Espiñeira, E. Dominis Prester, D. Donini, A. Dorner, D. Doro, M. Elsaesser, D. Fallah Ramazani, V. Fattorini, A. Fonseca, M.V. Font, L. Fruck, C. Fukami, S. Fukazawa, Y. García López, R.J. Garczarczyk, M. Gasparyan, S. Gaug, M. Giglietto, N. Giordano, F. Gliwny, P. Godinović, N. Green, J.G. Green, D. Hadasch, D. Hahn, A. Heckmann, L. Herrera, J. Hoang, J. Hrupec, D. Hütten, M. Inada, T. Ishio, K. Iwamura, Y. Jiménez Martínez, I. Jormanainen, J. Jouvin, L. Karjalainen, M. Kerszberg, D. Kobayashi, Y. Kubo, H. Kushida, J. Lamastra, A. Lelas, D. Leone, F. Lindfors, E. Linhoff, L. Lombardi, S. Longo, F. López-Coto, R. López-Moya, M. López-Oramas, A. Loporchio, S. Machado de Oliveira Fraga, B. Maggio, C. Majumdar, P. Makariev, M. Mallamaci, M. Maneva, G. Manganaro, M. Mannheim, K. Maraschi, L. Mariotti, M. Martínez, M. Mazin, D. Menchiari, S. Mender, S. Mićanović, S. Miceli, D. Miener, T. Miranda, J.M. Mirzoyan, R. Molina, E. Moralejo, A. Morcuende, D. Moreno, V. Moretti, E. Nakamori, T. Nava, L. Neustroev, V. Nigro, C. Nilsson, K. Nishijima, K. Noda, K. Nozaki, S. Ohtani, Y. Oka, T. Otero-Santos, J. Paiano, S. Palatiello, M. Paneque, D. Paoletti, R. Paredes, J.M. Pavletić, L. Peñil, P. Persic, M. Pihet, M. Prada Moroni, P.G. Prandini, E. Priyadarshi, C. Puljak, I. Rhode, W. Ribó, M. Instituto de Astrofísica de Canarias Dpto. de Astrofísica Universidad de La Laguna La Laguna TenerifeE-38200 Spain Università di Udine INFN Trieste UdineI-33100 Italy RomeI-00136 Italy ETH Zürich ZürichCH-8093 Switzerland Bellaterra BarcelonaE-08193 Spain The University of Tokyo Chiba Kashiwa277-8582 Japan Technische Universität Dortmund DortmundD-44221 Germany Zagreb10000 Croatia IPARCOS Institute EMFTEL Department Universidad Complutense de Madrid MadridE-28040 Spain URCA RJ Rio de Janeiro22290-180 Brazil Università di Padova INFN PadovaI-35131 Italy University of Lodz Faculty of Physics and Applied Informatics Department of Astrophysics Lodz90-236 Poland Università di Siena INFN Pisa SienaI-53100 Italy ZeuthenD-15738 Germany Max-Planck-Institut für Physik MünchenD-80805 Germany Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n Granada18008 Spain Università di Pisa INFN Pisa PisaI-56126 Italy Universitat de Barcelona ICCUB IEEC-UB BarcelonaE-08028 Spain A. Alikhanyan National Science Laboratory Yerevan0036 Armenia Centro de Investigaciones Energéticas Medioambientales y Tecnológicas MadridE-28040 Spain INFN Sezione di Torino Università degli Studi di Torino TorinoI-10125 Italy INFN Sezione di Bari Dipartimento Interateneo di Fisica Università e del Politecnico di Bari BariI-70125 Italy University of Rijeka Department of Physics Rijeka51000 Croatia Universität Würzburg WürzburgD-97074 Germany Finnish Centre for Astronomy with ESO University of Turku TurkuFI-20014 Finland Departament de Física CERES-IEEC Universitat Autònoma de Barcelona BellaterraE-08193 Spain Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima739-8526 Japan ICRANet-Armenia NAS RA Yerevan0019 Armenia Split21000 Croatia Josip Juraj Strossmayer University of Osijek Department of Physics Osijek31000 Croatia Department of Physics Kyoto University Kyoto

The origin of Galactic Cosmic rays (GCRs), whose spectrum extends to PeV energies, is one of the longest-standing problems in astroparticle physics. One of the main sources of GCRs are regarded to be Supernova remnants (SNRs). While SNRs are known to accelerate protons, so far there is no evidence that SNRs can accelerate CRs to PeV energies. Providing that 10% of the parent Cosmic ray energy is converted to gamma rays, the gamma-ray spectrum extending up to 100 TeV would be a signature of a so-called Galactic PeVatron, an object responsible for the production of protons up to the knee of the Cosmic ray spectrum. The current multi-wavelength data indicate that HESS J1809-193 is one of the most promising Galactic PeVatron candidates. So far, no firm identification on the source nature has been established as there are several possible counterparts at lower energies;one of them being SNR G11.00.0. We report here the results of an observational campaign performed by the MAGIC telescopes on HESS J1809-193 since 2019 in the very-high-energy gamma-ray domain (E>100 GeV). The data were obtained with the Very Large Zenith Angle (VLZA) technique, which increased the collection area significantly to about one square kilometer. We used 60 hours of collected VLZA data to explore the spectrum and the morphology of the source at energies above several TeV. © 2022 Sissa Medialab Srl. All rights reserved.

关键词： Cosmology

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ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions − XVII. High-mass star-formation through a large-scale collapse in IRAS 15394−5358

arXiv

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arXiv 2024年

作者： Das, Swagat R. Merello, Manuel Bronfman, Leonardo Liu, Tie Garay, Guido Stutz, Amelia Mardones, Diego Zhou, Jian-Wen Sanhueza, Patricio Liu, Hong-Li Vázquez-Semadeni, Enrique Gómez, Gilberto C. Palau, Aina Tej, Anandmayee Xu, Feng-Wei Baug, Tapas Dewangan, Lokesh K. He, Jinhua Zhu, Lei Li, Shanghuo Juvela, Mika Saha, Anindya Issac, Namitha Hwang, Jihye Nazeer, Hafiz Toth, L. Viktor Departamento de Astronomía Universidad de Chile Las Condes Santiago7591245 Chile Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Departamento de Astronomía Universidad de Concepción Av. Esteban Iturra s/n Distrito Universitario 160-C Chile Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 Bonn53121 Germany National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Astronomical Science Program The Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan School of Physics and Astronomy Yunnan University Kunming650091 China Instituto de Radioastronomía y Astrofísica Universidad Nacional Autónoma de México Apdo. Postal 3-72 Michoacán Morelia58089 Mexico Indian Institute of Space Science and Technology Kerala Thiruvananthapuram695 547 India Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Department of Astronomy School of Physics Peking University Beijing100871 China S. N. Bose National Centre for Basic Sciences Block-JD Sector-III Salt Lake City Kolkata700106 India Physical Research Laboratory Navrangpura Ahmedabad380 009 India Yunnan Observatories Chinese Academy of Sciences 396 Yang-fangwang Guandu District Kunming650216 China Chinese Academy of Sciences South America Center for Astronomy National Astronomical Observatories CAS Beijing100101 China Max Planck Institute of Astronoy Königstuhl 17 Heidelberg69117 Germany SOFIA Science Centre USRA NASA Ames Research Centre MS-12 N232 Moffett FieldCA94035 United States Department of Physics University of Helsinki PO Box 64 HelsinkiFI-00014 Finland Korea Astronomy and Space Science Institute 776 Daedeokdaero Yuseong-gu Daejeon34055 Korea Republic of Institute of Physics and Astronomy Eotvos Lorand University Pazmany Peter setany 1/A BudapestH-1117 Hungary

Hub-filament systems are considered as natural sites for high-mass star formation. Kinematic analysis of the surroundings of hub-filaments is essential to better understand high-mass star formation within such systems. In this work, we present a detailed study of the massive Galactic protocluster IRAS 15394−5358, using continuum and molecular line data from the ALMA Three-millimeter Observations of Massive Star-forming Regions (ATOMS) survey. The 3 mm dust continuum map reveals the fragmentation of the massive (M = 843 M☉) clump into six cores. The core C-1A is the largest (radius = 0.04 pc), the most massive (M = 157 M☉), and lies within the dense central region, along with two smaller cores (M = 7 and 3 M☉). The fragmentation process is consistent with the thermal Jeans fragmentation mechanism and virial analysis shows that all the cores have small virial parameter values (αvir 13CO+ shows that the massive clump is associated with a hub-filament system, where the central hub is linked with four filaments. A sharp velocity gradient is observed towards the hub, suggesting a global collapse where the filaments are actively feeding the hub. We discuss the role of global collapse and the possible driving mechanisms for the massive star formation activity in the protocluster. Copyright © 2024, The Authors. All rights reserved.

关键词： Kinematics

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In-situ observation of hydrogen nanobubbles formation on graphene surface by AFM-SECM

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Electrochimica Acta 2024年 493卷

作者： Kholimatussadiah, Septia Hsu, Chia-Ling Ke, Shang-Wei Chou, Tsu-Chin Wu, Yung-Fu Yakimova, Rositsa Kumatani, Akichika Chen, Kuei-Hsien Chen, Li-Chyong Du, He-Yun Department of Physics National Taiwan University Taipei 10617 Taiwan Nano Science and Technology Taiwan International Graduate Program Academia Sinica Taipei 10617 Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei 10617 Taiwan Center of Atomic Initiative for New Materials National Taiwan University Taipei 10617 Taiwan Department of Chemical Engineering Ming Chi University of Technology New Taipei City24301 Taiwan Institute of Atomic and Molecular Sciences Academia Sinica Taipei 10617 Taiwan Institute of Analytical and Environmental Sciences National Tsing Hua University Hsinchu 300044 Taiwan Department of Physics Chemistry and Biology Linköping University SE-581 83 Linköping Sweden Institute of Engineering Innovation School of Engineering The University of Tokyo Tokyo 113-8656 Japan Saitama 332-0012 Japan Tohoku University Sendai980-8577 Japan Battery Research Center of Green Energy Ming Chi University of Technology New Taipei City24301 Taiwan Biochemical Technology R&D Center Ming Chi University of Technology New Taipei City24301 Taiwan Center for Sustainability and Energy Technologies Chang Gung University Taoyuan City33302 Taiwan

Gas bubble evolution is an important phenomenon in many electrochemical processes and it is highly sensitive to the surface properties. Here we visualize the gas bubble dynamics on the surface of different graphene substrates during hydrogen evolution reaction (HER) using atomic force microscopy combined with scanning electrochemical microscopy. The low overpotential and low surface hydrophobicity of few-layer graphene formed on C-phase SiC causes the uniform distribution of hydrogen nanobubbles, which easily depart from the surface during the reaction. Conversely, the high overpotential and more hydrophobic surface of HOPG induces hydrogen bubbles to linger on the surface for an extended duration, leading to its accumulation and the subsequent formation of microbubbles. This in-situ nanoscale electrochemical mapping of hydrogen bubble dynamics provides new insight into electrocatalytic HER that occurs on non-metal electrodes. © 2024 Elsevier Ltd

关键词： Graphene

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