624 research outputs found

    Structural investigations on Ďľ\epsilon-FeGe at high pressure and low temperature

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    The structural parameters of Ďľ\epsilon-FeGe have been determined at ambient conditions using single crystal refinement. Powder diffraction have been carried out to determine structural properties and compressibility for pressures up to 30 GPa and temperatures as low as 82 K. The discontinuous change in the pressure dependence of the shortest Fe-Ge interatomic distance might be interpreted as a symmetry-conserving transition and seems to be related to a magnetic phase boundary line.Comment: 4 pages, 5 figure

    Electronic and Thermoelectric Properties of RuIn_{3-x}A_{x} (A = Sn, Zn)

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    Recently, we reported [M. Wagner et al., J. Mater. Res. 26, 1886 (2011)] transport measurements on the semiconducting intermetallic system RuIn3 and its substitution derivatives RuIn_{3-x}A_{x} (A = Sn, Zn). Higher values of the thermoelectric figure of merit (zT = 0.45) compared to the parent compound were achieved by chemical substitution. Here, using density functional theory based calculations, we report on the microscopic picture behind the measured phenomenon. We show in detail that the electronic structure of the substitution variants of the intermetallic system RuIn_{3-x}A_{x} (A = Sn, Zn) changes in a rigid-band like fashion. This behavior makes possible the fine tuning of the substitution concentration to take advantage of the sharp peak-like features in the density of states of the semiconducting parent compound. Trends in the transport properties calculated using the semi-classical Boltzmann transport equations within the constant scattering time approximation are in good agreement with the former experimental results for RuIn_{3-x}Sn_{x}. Based on the calculated thermopower for the p-doped systems, we reinvestigated the Zn-substituted derivative and obtained ZnO-free RuIn_{3-x}Zn_{x}. The new experimental results are consistent with the calculated trend in thermopower and yield large zT value of 0.8.Comment: PRB Accepted, 11 pages, 10 figure

    A lapa do Bugio

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    A jazida prÊ-histórica do Bugio constitui uma das mais importantes grutas sepulcrais da faixa estremenha. Encontrava-se intacta à data das primeiras escavaçþes, realizadas em 1957 e 1958. Vicissitudes vårias que motivaram a dissolução da primeira equipa e favoreceram diversas depredaçþes, entretanto realizadas, impediram que, antes do recomeço dos trabalhos, em 1966, mesmo dos materiais recuperados, se pudessem extrair todas as informaçþes neles potencialmente contidas. Foi possível, a partir do estudo exaustivo do espólio conservado no Museu de Sesimbra e no recolhido nas escavaçþes de 1966, estabelecer a seguinte sucessão cronológica-cultural: Primeira ocupação - corresponde talvez à ocupação mais importante, integråvel no Neolítico recente-final estremenho. Estreitas analogias com o "horizonte dolmÊnico" identificado na vizinha Lapa do Fumo e datado pelo rådio-carbono de 3090 ¹ 160 a. C. (SERRÃO,1978). A datação realizada no Bugio deu 2800 ¹ 45 a.C. Segunda ocupação- corresponde muito provavelmente a momento inicial (ou pleno) do Calcolítico, definido pela presença de raros produtos, como o recipiente de osso recolhido na sep. 7 e "ídolos" de calcårio, de osso e marfim. Terceira ocupação - Calcolítico final, campaniforme - representada pelos Grupos de Palmela e Inciso. Trata-se da ocupação menos importante, excessivamente valorizada em trabalhos anteriores, talvez pela grande dispersão de fragmentos cerâmicos que não ultrapassam, contudo, nove recipientes (alguns deles representados por apenas um fragmento): taças em calote - (I), de bordo espessado - (I), de tipo Palmela - (I), caçoilas acampanadas - (2), e vasos campaniformes - (2), alÊm de dois recipientes de tipologia mal definida.Le gisement prÊhistorique de Bugio est l 'une des plus importantes grottes sÊpulcrales du littoral de l'EstrÊmadure. Elle a ÊtÊ trouvÊe intacte lors des premières fouilles, rÊalisÊes en 1957 et 1958. Diverses vicissitudes, qui devaient aboutir à la dissolution de la première Êquipe de fouilleurs et favoriser le pillage du site, empêchèrent la difusion de toute information avant la reprise des travaux en 1966, même sur le matÊriel rÊcupÊrÊ. A partir de l' Êtude exhaustive du mobilier conservÊ au MusÊe de Sesimbra et de celui qui a ÊtÊ dÊcouvert en 1966, on a pu Êtablir les niveaux chronologiques suivants: Première occupation, peut-être la plus importante, s'intÊgrant dans le NÊolithique rÊcent et final de l'EstrÊmadure, prÊsentant d' Êtroites analogies avec "l'horizon dolmÊnique" identifiÊ sur le site voisin de Lapa do Fumo, datÊ de 3090 ¹ 160 a.C. par radio-carbone (SERRÃO, 1978). La datation obtenue à Bugio est de 2800 ¹ 45 a.C.. Seconde occupation, correspondant très probablement à la phase initiale ou mÊdiane du Chalcolithique, dÊfinie par de rares productions, comme le rÊcipient en os recueilli dans la sÊpulture 7 et les "idoles" en calcaire, en os et en ivoire. Troisième occupation (Chalcolithique final, Campaniforme) reprÊsentÊe par les Groupes de Palmela et incisÊ. Il s'agit d'une occupation moins importante, surÊvaluÊe dans les travaux antÊrieurs, peut-être en raison de la grande dispersion des fragments de cÊramiques qui ne correspondaient, cependant, qu'à neuf rÊcipients: coupes en calotte (1 ), coupes au bord Êpais (1), coupes de type de Palmela (1), casseroles en forme de cloche (2), vases campaniformes (2) et deux rÊcipients à la typologie mal dÊfinie

    Guia de coleta de dados de ceratoconjuntivite bovina infecciosa (CBI).

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    Monitoramento de surtos; Registro dos dados nas tabelas; Registro fotogrĂĄfico; Coleta de material para anĂĄlises microbiolĂłgicasbitstream/item/176394/1/Documentos-149.pd

    Field-induced transition within the superconducting state of CeRh2As2

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    Funding: We acknowledge funding from the Physics of Quantum Materials department and the research group “Physics of Unconventional Metals and Superconductors (PUMAS)” of the Max Planck Society. C.G. and E.H. acknowledge support from the German Science Foundation (DFG) through grant GE 602/4-1 Fermi-NESt. P.M.R.B. was supported by the Marsden Fund Council from Government funding, managed by Royal Society Te Apārangi. R.K. is supported by the DFG through project. no. KU 3287/1-1. D.F.A. was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under award DE-SC0021971.Materials with multiple superconducting phases are rare. Here, we report the discovery of two-phase unconventional superconductivity in CeRh2As2 Using thermodynamic probes, we establish that the superconducting critical field of its high-field phase is as high as 14 tesla, even though the transition temperature is only 0.26 kelvin. Furthermore, a transition between two different superconducting phases is observed in a c axis magnetic field. Local inversion-symmetry breaking at the cerium sites enables Rashba spin-orbit coupling alternating between the cerium sublayers. The staggered Rashba coupling introduces a layer degree of freedom to which the field-induced transition and high critical field seen in experiment are likely related.PostprintPostprintPeer reviewe

    Utilização de imagens termogråficas para diagnóstico de ceratoconjuntivite infecciosa bovina em animais da raça Hereford.

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    Resumo.Fernando Flores Cardoso, Daniel Portella Montardo, JosĂŠ Carlos Ferrugem Moraes, Marcos FlĂĄvio Silva Borba, Sandro da Silva Camargo, editores tĂŠcnicos

    Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors

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    Layered d-metal pnictide oxides are a unique class of compounds which consists of characteristic d-metal pnictide layers and metal oxide layers. More than 100 of these layered compounds, including the recently discovered Fe-based superconducting pnictide oxides, can be classified into 9 structure types. These structure types and the chemical and physical properties of the characteristic d-metal pnictide layers and metal oxide layers of the layered d-metal pnictide oxides are reviewed and discussed. Furthermore, possible approaches to design new superconductors based on these layered d-metal pnictide oxides are proposed.Comment: 29 pages including 6 tables and 2 figure

    Geometric deep learning as a potential tool for antimicrobial peptide prediction

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    Antimicrobial peptides (AMPs) are components of natural immunity against invading pathogens. They are polymers that fold into a variety of three-dimensional structures, enabling their function, with an underlying sequence that is best represented in a non-flat space. The structural data of AMPs exhibits non-Euclidean characteristics, which means that certain properties, e.g., differential manifolds, common system of coordinates, vector space structure, or translation-equivariance, along with basic operations like convolution, in non-Euclidean space are not distinctly established. Geometric deep learning (GDL) refers to a category of machine learning methods that utilize deep neural models to process and analyze data in non-Euclidean settings, such as graphs and manifolds. This emerging field seeks to expand the use of structured models to these domains. This review provides a detailed summary of the latest developments in designing and predicting AMPs utilizing GDL techniques and also discusses both current research gaps and future directions in the field

    Brane-World Gravity

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    The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+\textit{d}-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the \textit{d} extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak (∟\sim TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review analyzes the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall--Sundrum models. We also cover the simplest brane-world models in which 4-dimensional gravity on the brane is modified at \emph{low} energies -- the 5-dimensional Dvali--Gabadadze--Porrati models. Then we discuss co-dimension two branes in 6-dimensional models.Comment: A major update of Living Reviews in Relativity 7:7 (2004) "Brane-World Gravity", 119 pages, 28 figures, the update contains new material on RS perturbations, including full numerical solutions of gravitational waves and scalar perturbations, on DGP models, and also on 6D models. A published version in Living Reviews in Relativit
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