Base de dados : MEDLINE
Pesquisa : G01.358.500.875 [Categoria DeCS]
Referências encontradas : 13 [refinar]
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  1 / 13 MEDLINE  
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[PMID]:28684490
[Au] Autor:Lee DH
[Ad] Endereço:Department of Physics, University of California, Berkeley, CA 94720, USA. dunghai@berkeley.edu.
[Ti] Título:Hunting down unconventional superconductors.
[So] Source:Science;357(6346):32-33, 2017 07 07.
[Is] ISSN:1095-9203
[Cp] País de publicação:United States
[La] Idioma:eng
[Mh] Termos MeSH primário: Crescimento Demográfico
Supercondutividade
[Mh] Termos MeSH secundário: Conservação dos Recursos Naturais
Europa (Continente)
[Pt] Tipo de publicação:JOURNAL ARTICLE; COMMENT
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171019
[Lr] Data última revisão:
171019
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170708
[St] Status:MEDLINE
[do] DOI:10.1126/science.aan2657


  2 / 13 MEDLINE  
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[PMID]:28176678
[Au] Autor:Yaghoobpour Tari S; Wachowicz K; Gino Fallone B
[Ad] Endereço:Department of Medical Physics, Cross Cancer Institute, 11560, University Avenue, Edmonton, Alberta, T6G 1Z2, Canada. Department of Oncology, University of Alberta, 11560, University Avenue, Edmonton, Alberta, T6G 1Z2, Canada.
[Ti] Título:A non-axial superconducting magnet design for optimized patient access and minimal SAD for use in a Linac-MR hybrid: proof of concept.
[So] Source:Phys Med Biol;62(8):N147-N160, 2017 Apr 21.
[Is] ISSN:1361-6560
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:A prototype rotating hybrid magnetic resonance imaging system and linac has been developed to allow for simultaneous imaging and radiation delivery parallel to B . However, the design of a compact magnet capable of rotation in a small vault with sufficient patient access and a typical clinical source-to-axis distance (SAD) is challenging. This work presents a novel superconducting magnet design as a proof of concept that allows for a reduced SAD and ample patient access by moving the superconducting coils to the side of the yoke. The yoke and pole-plate structures are shaped to direct the magnetic flux appropriately. The outer surface of the pole plate is optimized subject to the minimization of a cost function, which evaluates the uniformity of the magnetic field over an ellipsoid. The magnetic field calculations required in this work are performed with the 3D finite element method software package Opera-3D. Each tentative design strategy is virtually modeled in this software package, which is externally controlled by MATLAB, with its key geometries defined as variables. The optimization variables are the thickness of the pole plate at control points distributed over the pole plate surface. A novel design concept as a superconducting non-axial magnet is introduced, which could create a large uniform B magnetic field with fewer geometric restriction. This non-axial 0.5 T superconducting magnet has a moderately reduced SAD of 123 cm and a vertical patient opening of 68 cm. This work is presented as a proof of principle to investigate the feasibility of a non-axial magnet with the coils located around the yoke, and the results encourage future design optimizations to maximize the benefits of this non-axial design.
[Mh] Termos MeSH primário: Algoritmos
Desenho de Equipamento
Campos Magnéticos
Imagem por Ressonância Magnética/instrumentação
Modelos Teóricos
Aceleradores de Partículas/instrumentação
Supercondutividade
[Mh] Termos MeSH secundário: Seres Humanos
Imagem por Ressonância Magnética/métodos
Software
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171024
[Lr] Data última revisão:
171024
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170209
[St] Status:MEDLINE
[do] DOI:10.1088/1361-6560/aa5f20


  3 / 13 MEDLINE  
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[PMID]:28082547
[Au] Autor:Shen KM
[Ad] Endereço:Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA. kmshen@cornell.edu.
[Ti] Título:Putting the squeeze on superconductivity.
[So] Source:Science;355(6321):133, 2017 01 13.
[Is] ISSN:1095-9203
[Cp] País de publicação:United States
[La] Idioma:eng
[Mh] Termos MeSH primário: Supercondutividade
[Pt] Tipo de publicação:JOURNAL ARTICLE; COMMENT
[Em] Mês de entrada:1707
[Cu] Atualização por classe:170714
[Lr] Data última revisão:
170714
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170114
[St] Status:MEDLINE
[do] DOI:10.1126/science.aak9803


  4 / 13 MEDLINE  
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[PMID]:28054624
[Au] Autor:Castelvecchi D
[Ti] Título:Quantum computers ready to leap out of the lab in 2017.
[So] Source:Nature;541(7635):9-10, 2017 01 03.
[Is] ISSN:1476-4687
[Cp] País de publicação:England
[La] Idioma:eng
[Mh] Termos MeSH primário: Computadores/tendências
Computadores/utilização
Laboratórios
Teoria Quântica
Pesquisa/instrumentação
Pesquisa/tendências
[Mh] Termos MeSH secundário: Supercondutividade
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1702
[Cu] Atualização por classe:170203
[Lr] Data última revisão:
170203
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170106
[St] Status:MEDLINE
[do] DOI:10.1038/541009a


  5 / 13 MEDLINE  
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[PMID]:27482542
[Au] Autor:Misawa T; Nomura Y; Biermann S; Imada M
[Ad] Endereço:Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
[Ti] Título:Self-optimized superconductivity attainable by interlayer phase separation at cuprate interfaces.
[So] Source:Sci Adv;2(7):e1600664, 2016 07.
[Is] ISSN:2375-2548
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Stabilizing superconductivity at high temperatures and elucidating its mechanism have long been major challenges of materials research in condensed matter physics. Meanwhile, recent progress in nanostructuring offers unprecedented possibilities for designing novel functionalities. Above all, thin films of cuprate and iron-based high-temperature superconductors exhibit remarkably better superconducting characteristics (for example, higher critical temperatures) than in the bulk, but the underlying mechanism is still not understood. Solving microscopic models suitable for cuprates, we demonstrate that, at an interface between a Mott insulator and an overdoped nonsuperconducting metal, the superconducting amplitude is always pinned at the optimum achieved in the bulk, independently of the carrier concentration in the metal. This is in contrast to the dome-like dependence in bulk superconductors but consistent with the astonishing independence of the critical temperature from the carrier density x observed at the interfaces of La2CuO4 and La2-x Sr x CuO4. Furthermore, we identify a self-organization mechanism as responsible for the pinning at the optimum amplitude: An emergent electronic structure induced by interlayer phase separation eludes bulk phase separation and inhomogeneities that would kill superconductivity in the bulk. Thus, interfaces provide an ideal tool to enhance and stabilize superconductivity. This interfacial example opens up further ways of shaping superconductivity by suppressing competing instabilities, with direct perspectives for designing devices.
[Mh] Termos MeSH primário: Modelos Teóricos
Supercondutividade
[Mh] Termos MeSH secundário: Cobre/química
Lantânio/química
Óxidos/química
Temperatura Ambiente
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (La2CuO4); 0 (Oxides); 6I3K30563S (Lanthanum); 789U1901C5 (Copper)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170504
[Lr] Data última revisão:
170504
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160803
[St] Status:MEDLINE
[do] DOI:10.1126/sciadv.1600664


  6 / 13 MEDLINE  
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[PMID]:27152327
[Au] Autor:Robbins SW; Beaucage PA; Sai H; Tan KW; Werner JG; Sethna JP; DiSalvo FJ; Gruner SM; Van Dover RB; Wiesner U
[Ad] Endereço:Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
[Ti] Título:Block copolymer self-assembly-directed synthesis of mesoporous gyroidal superconductors.
[So] Source:Sci Adv;2(1):e1501119, 2016 Jan.
[Is] ISSN:2375-2548
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Superconductors with periodically ordered mesoporous structures are expected to have properties very different from those of their bulk counterparts. Systematic studies of such phenomena to date are sparse, however, because of a lack of versatile synthetic approaches to such materials. We demonstrate the formation of three-dimensionally continuous gyroidal mesoporous niobium nitride (NbN) superconductors from chiral ABC triblock terpolymer self-assembly-directed sol-gel-derived niobium oxide with subsequent thermal processing in air and ammonia gas. Superconducting materials exhibit a critical temperature (T c) of about 7 to 8 K, a flux exclusion of about 5% compared to a dense NbN solid, and an estimated critical current density (J c) of 440 A cm(-2) at 100 Oe and 2.5 K. We expect block copolymer self-assembly-directed mesoporous superconductors to provide interesting subjects for mesostructure-superconductivity correlation studies.
[Mh] Termos MeSH primário: Polímeros
Supercondutividade
[Mh] Termos MeSH secundário: Nióbio/química
Polímeros/química
Porosidade
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Nm] Nome de substância:
0 (Polymers); 05175J654G (Niobium)
[Em] Mês de entrada:1612
[Cu] Atualização por classe:170220
[Lr] Data última revisão:
170220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160507
[St] Status:MEDLINE
[do] DOI:10.1126/sciadv.1501119


  7 / 13 MEDLINE  
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[PMID]:27084590
[Au] Autor:Gerbershagen A; Meer D; Schippers JM; Seidel M
[Ad] Endereço:Paul Scherrer Institute, Switzerland. Electronic address: alexander.gerbershagen@psi.ch.
[Ti] Título:A novel beam optics concept in a particle therapy gantry utilizing the advantages of superconducting magnets.
[So] Source:Z Med Phys;26(3):224-37, 2016 Sep.
[Is] ISSN:1876-4436
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:PURPOSE: A first order design of the beam optics of a superconducting proton therapy gantry beam is presented. The possibilities of superconducting magnets with respect to the beam optics such as strong fields, large apertures and superposition of different multipole fields have been exploited for novel concepts in a gantry. Since various techniques used in existing gantries have been used in our first design steps, some examples of the existing superconducting gantry designs are described and the necessary requirements of such a gantry are explained. METHODS: The study of a gantry beam optics design is based on superconducting combined function magnets. The simulations have been performed in first order with the conventional beam transport codes. RESULTS: The superposition of strong dipole and quadrupole fields generated by superconducting magnets enables the introduction of locally achromatic bending sections without increasing the gantry size. A rigorous implementation of such beam optics concepts into the proposed gantry design dramatically increases the momentum acceptance compared to gantries with normal conducting magnets. In our design this large acceptance has been exploited by the implementation of a degrader within the gantry and a potential possibility to use the same magnetic field for all energies used in a treatment, so that the superconducting magnets do not have to vary their fields during a treatment. This also enables very fast beam energy changes, which is beneficial for spreading the Bragg peak over the thickness of the tumor. CONCLUSIONS: The results show an improvement of its momentum acceptance. Large momentum acceptance in the gantry creates a possibility to implement faster dose application techniques.
[Mh] Termos MeSH primário: Projeto Auxiliado por Computador
Imãs
Terapia com Prótons/instrumentação
Prótons/uso terapêutico
Planejamento da Radioterapia Assistida por Computador/métodos
Supercondutividade
[Mh] Termos MeSH secundário: Desenho de Equipamento
Análise de Falha de Equipamento
Dispositivos Ópticos
Dosagem Radioterapêutica
Espalhamento de Radiação
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Protons)
[Em] Mês de entrada:1704
[Cu] Atualização por classe:170426
[Lr] Data última revisão:
170426
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160417
[St] Status:MEDLINE


  8 / 13 MEDLINE  
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[PMID]:27051872
[Au] Autor:Bugnet M; Löffler S; Hawthorn D; Dabkowska HA; Luke GM; Schattschneider P; Sawatzky GA; Radtke G; Botton GA
[Ad] Endereço:Department of Materials Science and Engineering and the Canadian Centre for Electron Microscopy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.
[Ti] Título:Real-space localization and quantification of hole distribution in chain-ladder Sr3Ca11Cu24O41 superconductor.
[So] Source:Sci Adv;2(3):e1501652, 2016 03.
[Is] ISSN:2375-2548
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Understanding the physical properties of the chain-ladder Sr3Ca11Cu24O41 hole-doped superconductor has been precluded by the unknown hole distribution among chains and ladders. We use electron energy-loss spectrometry (EELS) in a scanning transmission electron microscope (STEM) at atomic resolution to directly separate the contributions of chains and ladders and to unravel the hole distribution from the atomic scale variations of the O-K near-edge structures. The experimental data unambiguously demonstrate that most of the holes lie within the chain layers. A quantitative interpretation supported by inelastic scattering calculations shows that about two holes are located in the ladders, and about four holes in the chains, shedding light on the electronic structure of Sr3Ca11Cu24O41. Combined atomic resolution STEM-EELS and inelastic scattering calculations is demonstrated as a powerful approach toward a quantitative understanding of the electronic structure of cuprate superconductors, offering new possibilities for elucidating their physical properties.
[Mh] Termos MeSH primário: Metais/química
Nanoestruturas/química
Supercondutividade
[Mh] Termos MeSH secundário: Cristalografia por Raios X
Modelos Moleculares
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Metals)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170504
[Lr] Data última revisão:
170504
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160407
[St] Status:MEDLINE
[do] DOI:10.1126/sciadv.1501652


  9 / 13 MEDLINE  
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[PMID]:27034989
[Au] Autor:Putzke C; Malone L; Badoux S; Vignolle B; Vignolles D; Tabis W; Walmsley P; Bird M; Hussey NE; Proust C; Carrington A
[Ad] Endereço:H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
[Ti] Título:Inverse correlation between quasiparticle mass and T c in a cuprate high-T c superconductor.
[So] Source:Sci Adv;2(3):e1501657, 2016 03.
[Is] ISSN:2375-2548
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Close to a zero-temperature transition between ordered and disordered electronic phases, quantum fluctuations can lead to a strong enhancement of electron mass and to the emergence of competing phases such as superconductivity. A correlation between the existence of such a quantum phase transition and superconductivity is quite well established in some heavy fermion and iron-based superconductors, and there have been suggestions that high-temperature superconductivity in copper-oxide materials (cuprates) may also be driven by the same mechanism. Close to optimal doping, where the superconducting transition temperature T c is maximal in cuprates, two different phases are known to compete with superconductivity: a poorly understood pseudogap phase and a charge-ordered phase. Recent experiments have shown a strong increase in quasiparticle mass m* in the cuprate YBa2Cu3O7-δ as optimal doping is approached, suggesting that quantum fluctuations of the charge-ordered phase may be responsible for the high-T c superconductivity. We have tested the robustness of this correlation between m* and T c by performing quantum oscillation studies on the stoichiometric compound YBa2Cu4O8 under hydrostatic pressure. In contrast to the results for YBa2Cu3O7-δ, we find that in YBa2Cu4O8, the mass decreases as T c increases under pressure. This inverse correlation between m* and T c suggests that quantum fluctuations of the charge order enhance m* but do not enhance T c.
[Mh] Termos MeSH primário: Elétrons
Supercondutividade
Temperatura Ambiente
[Mh] Termos MeSH secundário: Cobre/química
Campos Magnéticos
Pressão
Termometria
Temperatura de Transição
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
789U1901C5 (Copper); T8BEA5064F (cuprous oxide)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170504
[Lr] Data última revisão:
170504
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160402
[St] Status:MEDLINE
[do] DOI:10.1126/sciadv.1501657


  10 / 13 MEDLINE  
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[PMID]:27001398
[Au] Autor:Kodama N; Kose K
[Ad] Endereço:Institute of Applied Physics, University of Tsukuba.
[Ti] Título:Echo-Planar Imaging for a 9.4 Tesla Vertical-Bore Superconducting Magnet Using an Unshielded Gradient Coil.
[So] Source:Magn Reson Med Sci;15(4):395-404, 2016 Oct 11.
[Is] ISSN:1880-2206
[Cp] País de publicação:Japan
[La] Idioma:eng
[Ab] Resumo:Echo-planar imaging (EPI) sequences were developed for a 9.4 Tesla vertical standard bore (~54 mm) superconducting magnet using an unshielded gradient coil optimized for live mice imaging and a data correction technique with reference scans. Because EPI requires fast switching of intense magnetic field gradients, eddy currents were induced in the surrounding metallic materials, e.g., the room temperature bore, and this produced serious artifacts on the EPI images. We solved the problem using an unshielded gradient coil set of proper size (outer diameter = 39 mm, inner diameter = 32 mm) with time control of the current rise and reference scans. The obtained EPI images of a phantom and a plant sample were almost artifact-free and demonstrated the promise of our approach.
[Mh] Termos MeSH primário: Imagem Ecoplanar/métodos
[Mh] Termos MeSH secundário: Animais
Apium graveolens
Artefatos
Imagem Ecoplanar/instrumentação
Desenho de Equipamento
Processamento de Imagem Assistida por Computador/métodos
Campos Magnéticos
Imãs
Metais
Camundongos
Imagens de Fantasmas
Supercondutividade
Temperatura Ambiente
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Metals)
[Em] Mês de entrada:1701
[Cu] Atualização por classe:171024
[Lr] Data última revisão:
171024
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160323
[St] Status:MEDLINE



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