7,151 research outputs found

    Electronic structure of the ferromagnetic superconductor UCoGe from first principles

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    The superconductor UCoGe is analyzed with electronic structure calculations using Linearized Augmented Plane Wave method based on Density Functional Theory. Ferromagnetic and antiferromagnetic calculations with and without correlations (via LDA+U) were done. In this compound the Fermi level is situated in a region where the main contribution to DOS comes from the U-5f orbital. The magnetic moment is mainly due to the Co-3d orbital with a small contribution from the U-5f orbital. The possibility of fully non-collinear magnetism in this compound seems to be ruled out. These results are compared with the isostructural compound URhGe, in this case the magnetism comes mostly from the U-5f orbital

    The loss of anisotropy in MgB2 with Sc substitution and its relationship with the critical temperature

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    The electrical conductivity anisotropy of the sigma-bands is calculated for the (Mg,Sc)B2 system using a virtual crystal model. Our results reveal that anisotropy drops with relatively little scandium content (< 30%); this behaviour coincides with the lowering of Tc and the reduction of the Kohn anomaly. This anisotropy loss is also found in the Al and C doped systems. In this work it is argued that the anisotropy, or 2D character, of the sigma-bands is an important parameter for the understanding of the high Tc found in MgB2

    Opinion: Should high-resolution differential mobility analyzers be used in mainstream aerosol studies?

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    Differential mobility analyzers (DMAs) are widely used instruments to measure the size distributions of submicron aerosols. High-resolution DMAs (HRDMAs) are defined here as plain DMAs maintaining a steady flow over an unusually broad range of sheath gas flow rates Q. HRDMAs, first developed by Georg Reischl's group, have existed for a long time. However, they have not been widely adopted, except in the size range below 10 nm, often in new particle formation studies. Here we question the commonly held view that HRDMAs are necessarily complex, bulky and expensive machines, mainly of interest in exotic applications outside mainstream aerosol research. Rather, many studies central to aerosol research could be carried out with HRDMAs with considerable advantage in size range, resolution, sensitivity and measurement speed. DMA manufacturers will hopefully take the challenge of developing commercial HRDMAs of complexity and cost comparable to those of today's commercial instruments, adapted for broad use by aerosol scientists, though with greatly improved flexibility and performance. Some of the technical challenges that still need to be overcome are discussed, such as the development of high-flow condensation counter detectors, and the control of high sample and sheath gas flow rates.</p

    Porous Silicon Biosensors

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    Atomic Multiplet and Charge Transfer Effects in the Resonant Inelastic X-Ray Scattering (RIXS) Spectra at the Nickel L2,3 Edge of NiF2

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    Resonant inelastic x-ray scattering (RIXS) is used to study the electronic structure of NiF2, which is the most ionic of the nickel compounds. RIXS can be viewed as a coherent two-steps process involving the absorption and the emission of x-rays. The soft x-ray absorption spectrum (XAS) at the metal L2,3 edge indicate the importance of atomic multiplet effects. RIXS spectra at L2,3 contain clearly defined emission peaks corresponding to d-excited states of Ni2+ at energies few eV below the elastic emission, which is strongly suppressed. These results are confirmed by atomic multiplet calculations using the Kramers-Heisenberg formula for RIXS processes. For larger energy losses, the emission spectra have a broad charge-transfer peak that results from the decay of hybridized Ni(3d)-F(2p) valence states. This is confirmed by comparison of the absorption and emission spectra recorded at the nickel L and fluorine K edges with F p and Ni d partial density of states using LDA + U calculations

    The ellipse law: Kirchhoff meets dislocations

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    In this paper we consider a nonlocal energyIαwhose kernel is obtained by addingto the Coulomb potential an anisotropic term weighted by a parameterα∈R. The caseα= 0corresponds to purely logarithmic interactions, minimised by the circle law;α= 1 correspondsto the energy of interacting dislocations, minimised by the semi-circle law. We show that forα∈(0,1) the minimiser is the normalised characteristic function of the domain enclosed bytheellipseof semi-axes√1−αand√1 +α. This result is one of the very few examples wherethe minimiser of a nonlocal anisotropic energy is explicitly computed. For the proof we borrowtechniques from fluid dynamics, in particular those related to Kirchhoff’s celebrated result thatdomains enclosed by ellipses are rotating vortex patches, calledKirchhoff ellipses

    Jaw biodynamic data for 24 patients with chronic unilateral temporomandibular disorder

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    This study assessed 24 adult patients, suffering from severe chronic unilateral pain diagnosed as temporomandibular joint (TMJ) disorder (TMD). The full dentate patients had normal occlusion and had never received an occlusal therapy, i.e., were with natural dental evolution/maturation. The following functional and dynamic factors were assessed: (1) chewing function; (2) TMJ remodeling or the condylar path (CP); and (3) lateral jaw motion or lateral guidance (LG). CPs were assessed using conventional axiography, and LG was assessed by K7 jaw tracking. Seventeen (71%) of the 24 (100%) patients consistently showed a habitual chewing side. The mean (standard deviation [SD]) of the CP angles was 47.90 (9.24) degrees. The mean (SD) of the LG angles was 42.95 (11.78) degrees. Data collection emerged from the conception of a new TMD paradigm where the affected side could be the habitual chewing side, the side with flatter lateral jaw motion or the side with an increased CP angle. These data may lead to improved diagnosis, therapy plans and evolution in TMD patients

    Aprovechamiento del cardo (Cynara cardunculus L.) para la producciĂłn de biomasa lignocelulĂłsica, aceite y forraje verde

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    Aprovechamiento del cardo (Cynara cardunculus L.) es una especie perteneciente a la familia de las Compuestas (Asteraceae) lo mismo que el cĂĄrtamo o el girasol. es una especie vivaz gracias a sus yemas de recambio que posee en el cuello de la raĂ­z estando muy bien adaptada a las condiciones del clima mediterrĂĄneo de veranos secos y calurosos
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