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arXiv 2017年

作者： Lim, Eun-Kyung Yurchyshyn, Vasyl Kumar, Pankaj Cho, Kyuhyoun Jiang, Chaowei Kim, Sujin Yang, Heesu Chae, Jongchul Cho, Kyung-Suk Lee, Jeongwoo Korea Astronomy and Space Science Institute 776 Daedeokdae-ro Yuseong-gu Daejeon305-348 Korea Republic of Big Bear Solar Observatory New Jersey Institute of Technology 40386 North Shore Lane Big Bear CityCA92314-9672 United States Heliophysics Science Division NASA Goddard Space Flight Center GreenbeltMD20771 United States Astronomy Program Department of Physics and Astronomy Seoul National University Seoul151-747 Korea Republic of Institute of Space Science and Applied Technology Harbin Institute of Technology Shenzhen518055 China University of Science and Technology Daejeon305-348 Korea Republic of

Solar flare ribbons provide an important clue to the magnetic reconnection process and associated magnetic field topology in the solar corona. We detected a large-scale secondary flare ribbon of a circular shape that developed in association with two successive M-class flares and one CME. The ribbon revealed interesting properties such as 1) a quasi-circular shape and enclosing the central active region;2) the size as large as 500" by 650", 3) successive brightenings in the clockwise direction at a speed of 160 km s-1starting from the nearest position to the flaring sunspots, 4) radial contraction and expansion in the northern and the southern part, respectively at speeds of ≤ 10 km s-1. Using multi-wavelength data from SDO, RHESSI, XRT, and Nobeyama, along with magnetic field extrapolations, we found that: 1) the secondary ribbon location is consistent with the field line footpoints of a fan-shaped magnetic structure that connects the flaring region and the ambient decaying field;2) the second M2.6 flare occurred when the expanding coronal loops driven by the first M2.0 flare encountered the background decayed field. 3) Immediately after the second flare, the secondary ribbon developed along with dimming regions. Based on our findings, we suggest that interaction between the expanding sigmoid field and the overlying fan-shaped field triggered the secondary reconnection that resulted in the field opening and formation of the quasi-circular secondary ribbon. We thus conclude that interaction between the active region and the ambient large-scale fields should be taken into account to fully understand the entire eruption process. Copyright © 2017, The Authors. All rights reserved.

关键词： Magnetic fields

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Correction: Self-assembly of a space-tessellating structure in the binary system of hard tetrahedra and octahedra

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Soft matter 2016年第34期12卷 7248页

作者： A T Cadotte J Dshemuchadse P F Damasceno R S Newman S C Glotzer Applied Physics Program University of Michigan Ann Arbor Michigan 48109 USA.

Correction for 'Self-assembly of a space-tessellating structure in the binary system of hard tetrahedra and octahedra' by A. T. Cadotte et al., Soft Matter, 2016, DOI: .

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Random close packing in protein cores

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Physical Review E 2016年第3期93卷 032415-032415页

作者： Jennifer C. Gaines W. Wendell Smith Lynne Regan Corey S. O'Hern Program in Computational Biology and Bioinformatics Yale University New Haven Connecticut 06520 USA Integrated Graduate Program in Physical and Engineering Biology (IGPPEB) Yale University New Haven Connecticut 06520 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Molecular Biophysics & Biochemistry Yale University New Haven Connecticut 06520 USA Department of Chemistry Yale University New Haven Connecticut 06520 USA Department of Mechanical Engineering & Materials Science Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA

Shortly after the determination of the first protein x-ray crystal structures, researchers analyzed their cores and reported packing fractions ϕ≈0.75, a value that is similar to close packing of equal-sized spheres. A limitation of these analyses was the use of extended atom models, rather than the more physically accurate explicit hydrogen model. The validity of the explicit hydrogen model was proved in our previous studies by its ability to predict the side chain dihedral angle distributions observed in proteins. In contrast, the extended atom model is not able to recapitulate the side chain dihedral angle distributions, and gives rise to large atomic clashes at side chain dihedral angle combinations that are highly probable in protein crystal structures. Here, we employ the explicit hydrogen model to calculate the packing fraction of the cores of over 200 high-resolution protein structures. We find that these protein cores have ϕ≈0.56, which is similar to results obtained from simulations of random packings of individual amino acids. This result provides a deeper understanding of the physical basis of protein structure that will enable predictions of the effects of amino acid mutations to protein cores and interfaces of known structure.

关键词： Protein structure Proteins

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In vivo evaluation of Zinc-containing nanostructured carbonated hydroxyapatite 27th

In vivo evaluation of Zinc-containing nanostructured carbona...

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27th Symposium and Annual Meeting of the International Society for Ceramics in Medicine, 2015

作者： Ribeiro, Simone Sartoretto, Suelen Cristina Resende, Rodrigo Uzeda, Marcelo Alves, Adriana Terezinha Santos, Silvia Albuquerque Pesce, Giovana Rossi, Alexandre Malta Granjeiro, José Mauro Miguel, Fúlvio Calasans-Maia, Mônica Diuana Graduate Program in Dentistry Fluminense Federal University Rua Mario Santos Braga Niterói Rio de Janeiro Brazil Applied Physics Department LABIOMAT Brazilian Center for Physics Research Rua Xavier Sigaud 150 Rio de Janeiro Rio de Janeiro Brazil Division of Bioengineering National Institute of Metrology Quality and Technology Duque de Caxias Rio de Janeiro Brazil Health Sciences Center Federal University of the Recôncavo of Bahia Santo Antônio de Jesus Bahia Brazil Department of Oral Surgery Dentistry School Fluminense Federal University Rua Mario Santos Braga 28 Niteroi Rio de Janeiro Brazil

ISBN: (纸本)9783035710403

The hydroxyapatite (HA) is a biocompatible and bioactive biomaterial used as bone substitute, however, the high crystallinity of HA and consequently its low solubility may be a limitation for its clinical use. In order to improve the biosorption of HA, the partial substitutions in the chemical structure and doping with small amounts of impurities have been study. The objective of this study was to evaluate the biocompatibility of 3% Zinc-containing nanostructured carbonated hydroxyapatite (ZncHA) compared with the carbonated hydroxyapatite (cHA), both synthesized at 37°C and non-sintered, using as control the stoichiometric HA microspheres in subcutaneous of mice. The X-ray Diffraction (XRD) and Vibrational Spectroscopy in Infra Red Fourier Transform (FTIR) were used to characterize the biomaterials. In vivo test was performed in BALB/c mice by implanting of HA, cHA and ZncHA spheres in the subcutaneous tissue for 1, and 9 weeks (n=5). The negative control consisted in incision without material implantation (Sham group). The samples were histological processed to descriptive analysis of biological effect. The microscopic analysis showed a similar granulation reaction between groups at the first experimental period. In 9 weeks there was a time dependent biosorption of cHA compared with other groups. In conclusion, the biomaterials tested were biocompatible and cHA group showed a significant biosorption in comparison with HA and ZncHA groups. The doping of zinc did not influence the biocompatibility of biomaterial, however, change the biosorption response. © 2016 Trans Tech Publications, Switzerland.

关键词： Hydroxyapatite

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Equilibrium self-assembly of small RNA viruses

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Physical Review E 2016年第3期93卷 032405-032405页

作者： R. F. Bruinsma M. Comas-Garcia R. F. Garmann A. Y. Grosberg Department of Physics and Astronomy University of California Los Angeles California 90095 USA Department of Chemistry and Biochemistry University of California Los Angeles California 90095 USA HIV Dynamics and Replication Program National Cancer Institute Frederick National Laboratory for Cancer Research Frederick Maryland 21702 School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Department of Physics and Center for Soft Matter Research New York University 4 Washington Place New York New York 10003 USA

We propose a description for the quasiequilibrium self-assembly of small, single-stranded (ss) RNA viruses whose capsid proteins (CPs) have flexible, positively charged, disordered tails that associate with the negatively charged RNA genome molecules. We describe the assembly of such viruses as the interplay between two coupled phase-transition-like events: the formation of the protein shell (the capsid) by CPs and the condensation of a large ss viral RNA molecule. Electrostatic repulsion between the CPs competes with attractive hydrophobic interactions and attractive interaction between neutralized RNA segments mediated by the tail groups. An assembly diagram is derived in terms of the strength of attractive interactions between CPs and between CPs and the RNA molecules. It is compared with the results of recent studies of viral assembly. We demonstrate that the conventional theory of self-assembly, which does describe the assembly of empty capsids, is in general not applicable to the self-assembly of RNA-encapsidating virions.

关键词： Self-assembly RNA Viruses

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Ethanol sensing properties of Zn2TiO4 particles

Ethanol sensing properties of Zn2TiO4 particles

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作者： Santhaveesuk, Theerapong Gardchareon, Atcharawon Wongratanaphisan, Duangmanee Choopun, Supab Physics Program Faculty of Science and Technology Pibulsongkram Rajabhat University Phitsanulok65000 Thailand Applied Physics Research Laboratory Department of Physics and Materials Science Faculty of Science Chiang Mai University Chiang Mai50200 Thailand Thailand Center of Excellence in Physics CHE Ratchathewi Bangkok10400 Thailand

Zn2TiO4 particles were prepared using the ball-milling technique in ethanol solution. Zn powder mixing with anatase-TiO2 powder at ratio of 2:1 by mole were used as raw materials. The mixed powders were grounded in agate mortar for 2 h, subsequently transferred into the ball-milled container with 1 mm zirconia balls and, then, milled for 24 h with ball-milling speeds of 200, 300 and 400 rpm. The ratio of powders and zirconia balls was 1:20 by weight. After that, the powders were washed using distilled water for 4 times, dried at 80 °C for 24 h and calcined at 1000 °C for 6 h. Morphological characteristics, chemical compositions, phase formation and defect of the synthesized powder were examined. The SEM result showed that the particle size was reduced as increase in the ball-milling speed, while the EDS showed that the Zn/Ti ratio was about 2. The XRD indicated that the synthesized powders exhibited a face center cubic Zn2TiO4 phase, confirming by the Raman spectra. The Zn2TiO4 particles were fabricated as the thick film ethanol sensor and tested under 50 and 200 ppm ethanol concentration at 300-500 °C. Our results suggest that the Zn2TiO4 particles can be used for detection of ethanol vapor, and the sensor current increased with increasing of ethanol concentration. The highest sensitivity observed at 500 °C was 3.83 for 200 rpm, 1.92 for 300 rpm and 2.36 for 400 rpm samples. This implied that, the Zn2TiO4 sensor can be a good candidate for high temperature application. © 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

关键词： Ball milling

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Cartan symmetries and global dynamical systems analysis in a higher-order modified teleparallel theory

arXiv

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arXiv 2017年

作者： Karpathopoulos, L. Basilakos, S. Leon, G. Paliathanasis, A. Tsamparlis, M. Faculty of Physics Department of Astronomy-Astrophysics-Mechanics University of Athens Panepistemiopolis Athens157 83 Greece Academy of Athens Research Center for Astronomy and Applied Mathematics Soranou Efesiou 4 Athens11527 Greece Departamento de Matemáticas Universidad Católica del Norte Avda. Angamos 0610 Casilla Antofagasta1280 Chile Instituto de Ciencias Físicas y Matemáticas Universidad Austral de Chile Valdivia Chile Department of Mathematics and Natural Sciences Core Curriculum Program Prince Mohammad Bin Fahd University Al Khobar31952 Saudi Arabia Institute of Systems Science Durban University of Technology PO Box 1334 Durban4000 South Africa

In a higher-order modified teleparallel theory cosmological we present analytical cosmological solutions. In particular we determine forms of the unknown potential which drives the scalar field such that the field equations form a Liouville integrable system. For the determination of the conservation laws we apply the Cartan symmetries. Furthermore, inspired from our solutions, a toy model is studied and it is shown that it can describe the Supernova data, while at the same time introduces dark matter components in the Hubble function. When the extra matter source is a stiff fluid then we show how analytical solutions for Bianchi I universes can be constructed from our analysis. Finally, we perform a global dynamical analysis of the field equations by using variables different from that of the Hubble-normalization. Copyright © 2017, The Authors. All rights reserved.

关键词： Cosmology

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In vivo evaluation of strontium-containing nanostructured carbonated hydroxyapatite 27th

In vivo evaluation of strontium-containing nanostructured ca...

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27th Symposium and Annual Meeting of the International Society for Ceramics in Medicine, 2015

作者： Kammer, Gabriel Maia Sartoretto, Suelen Cristina Resende, Rodrigo Uzeda, Marcelo Nascimento, Jhonathan Raphael Alves, Adriana Terezinha Calasans-Maia, José Rossi, Alexandre Granjeiro, José Mauro Calasans-Maia, Mônica Diuana Graduate Program in Dentistry Fluminense Federal University Rua Mario Santos Braga Niterói Rio de Janeiro Brazil Orthodontics Department Dentistry School Fluminense Federal University Rua Dr. Sylvio Henrique Browne Nova Friburgo Rio de Janeiro Brazil Applied Physics Department LABIOMAT Brazilian Center for Physics Research Rua Xavier Sigaud Rio de Janeiro Rio de Janeiro150 Brazil Division of Bioengineering National Institute of Metrology Quality and Technology Duque de Caxias Rio de Janeiro Brazil Department of Oral Surgery Dentistry School Fluminense Federal University Rua Mario Santos Braga 28 Niteroi Rio de Janeiro Brazil

ISBN: (纸本)9783035710403

Bone tissue is a composite material that has hydroxyapatite (HA) as its main inorganic phase component. The biological apatites have low crystallinity and contain cationic and anionic substitutions in their structure, which differ from the available synthetic ceramics. The purpose of this study is to evaluate the biocompatibility of nanostructured carbonated hydroxyapatite microspheres containing 5 wt% strontium (SrcHA) compared with the biocompatibility of carbonated hydroxyapatite (cHA), both synthesized at 37°C and non-sintered, used to control stoichiometric HA microspheres in subcutaneous tissue of mice. The biomaterials (BM) were characterized using X-ray Diffraction (XRD), Vibrational Spectroscopy in an Infrared Fourier Transform (VSIRFT) and Scanning Electron Microscopy (SEM). Forty five balb-C mice were randomly divided into four groups of 15 animals each: SrcHA, cHA, HA, and without material implantation (Sham group). All samples were histologically processed for descriptive evaluation of the biological effect. At each experimental period (1, 3 and 9 weeks), there was a higher biosorption of the tested biomaterials observed in contrast with the HA. The cHA group was the only group completely phagocytosed by macrophages and giant cells after 9 weeks. All biomaterials proved to be biocompatible, and the cHA and SrcHA 3% groups exhibited a faster bioabsorption in comparison with the control group. The doping of strontium did not cause a greater biological response after the 3 experimental periods. © 2016 Trans Tech Publications, Switzerland.

关键词： Hydroxyapatite

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SciPy 1.0—Fundamental algorithms for scientific computing in python

arXiv

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arXiv 2019年

作者： Virtanen, Pauli Gommers, Ralf Oliphant, Travis E. Haberland, Matt Reddy, Tyler Cournapeau, David Burovski, Evgeni Peterson, Pearu Weckesser, Warren Bright, Jonathan van der Walt, Stéfan J. Brett, Matthew Wilson, Joshua Millman, K. Jarrod Mayorov, Nikolay Nelson, Andrew R.J. Jones, Eric Kern, Robert Larson, Eric Carey, C.J. Polat, Ilhan Feng, Yu Moore, Eric W. VanderPlas, Jake Laxalde, Denis Perktold, Josef Cimrman, Robert Henriksen, Ian Quintero, E.A. Harris, Charles R. Archibald, Anne M. Ribeiro, Antônio H. Pedregosa, Fabian van Mulbregt, Paul University of Jyväskylä University of Jyväskylä FI-40014 Finland Quansight LLC AustinTX United States Ultrasound Imaging Mayo Clinic RochesterMN55902 United States Electrical Engineering Brigham Young University ProvoUT84604 United States Enthought Inc. AustinTX78701 United States Anaconda Inc AustinTX78701 United States BioResource and Agricultural Engineering Department California Polytechnic State University San Luis ObispoCA93407 United States Department of Mathematics University of California Los AngelesCA90025 United States Los Alamos National Laboratory Los AlamosNM87544 United States Independent Researcher Higher School of Economics Myasnitskaya 20 Moscow101000 Russia Independent Researcher Saue Estonia Department of Mechanics and Applied Mathematics Institute of Cybernetics Tallinn Technical University Akadeemia Rd 21 Tallinn Estonia Independent Researcher NY United States Berkeley Institute for Data Science University of California BerkeleyCA94720 United States School of Psychology University of Birmingham Edgbaston BirmighamB15 2TT United Kingdom Division of Biostatistics University of California BerkeleyCA94720 United States WayRay LLC Skolkovo Innovation Center Moscow143026 Russia Australian Nuclear Science and Technology Organisation Locked Bag 2001 Kirrawee DCNSW2232 Australia Institute for Learning and Brain Sciences University of Washington SeattleWA98195 United States College of Information and Computing Sciences University of Massachusetts Amherst AmherstMA01002 United States Berkeley Center for Cosmological Physics University of California BerkeleyCA94720 United States Bruker Biospin Corp. 15 Fortune Drive BillericaMA01821 United States University of Washington SeattleWA98195 United States New Technologies - Research Centre University of West Bohemia Univerzitní 8 Plzeň306 14 Czech Republic Oden Institute for Computational Engineering and Sciences University of Texas at Austin AustinTX7

SciPy is an open source scientific computing library for the Python programming language. SciPy 1.0 was released in late 2017, about 16 years after the original version 0.1 release. SciPy has become a de facto standard for leveraging scientific algorithms in the Python programming language, with more than 600 unique code contributors, thousands of dependent packages, over 100,000 dependent repositories, and millions of downloads per year. This includes usage of SciPy in almost half of all machine learning projects on GitHub, and usage by high profile projects including LIGO gravitational wave analysis and creation of the first-ever image of a black hole (M87). The library includes functionality spanning clustering, Fourier transforms, integration, interpolation, file I/O, linear algebra, image processing, orthogonal distance regression, minimization algorithms, signal processing, sparse matrix handling, computational geometry, and statistics. In this work, we provide an overview of the capabilities and development practices of the SciPy library and highlight some recent technical developments. Copyright © 2019, The Authors. All rights reserved.

关键词： Open source software

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Photonic Crystals: Light‐Patterned Crystallographic Direction of a Self‐Organized 3D Soft Photonic Crystal (Adv. Mater. 42/2017)

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Advanced Materials 2017年第42期29卷

作者： Zhi‐Gang Zheng Cong‐Long Yuan Wei Hu Hari Krishna Bisoyi Ming‐Jie Tang Zhen Liu Pei‐Zhi Sun Wei‐Qiang Yang Xiao‐Qian Wang Dong Shen Yannian Li Fangfu Ye Yan‐Qing Lu Guoqiang Li Quan Li Department of Physics East China University of Science and Technology Shanghai 200237 China Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State University Kent OH 44242 USA National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences Nanjing University Nanjing 210093 China Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Visual and Biomedical Optics Lab Department of Ophthalmology and Visual Science and Department of Electrical and Computer Engineering Ohio State University Columbus OH 43212 USA

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