ALBERT

Description: Multiferroic materials which simultaneously exhibit electric polarization and magnetism have attracted more and more attention due to their novel physical properties and promising applications. Here, we report the magnetic and ferroelectric properties of single phase perovskite manganites Dy 0.7 Sr 0.3 MnO 3 and Dy 0.6 Sr 0.4 MnO 3 by varying temperature and magnetic field. Our results reveal that there exist spin reversal and strong antiferromagnetic pinning effects in both compounds, as well as negative magnetization in Dy 0.6 Sr 0.4 MnO 3 . Moreover, upon Sr-doping, spontaneous electric polarizations have been observed and the maximum polarization value of Dy 0.7 Sr 0.3 MnO 3 is about 1000  μ C/m 2 while Dy 0.6 Sr 0.4 MnO 3 reaches to 2000  μ C/m 2 . The onset of the ferroelectric transition temperature is enhanced to be around 60 K. Our results indicate that the antiferromagnetic coupling is relevant to the ferroelectric properties of these fascinating multiferroic systems.

Description: The current simple nanofluid flooding method for tertiary or enhanced oil recovery is inefficient, especially when used with low nanoparticle concentration. We have designed and produced a nanofluid of graphene-based amphiphilic nanosheets that is very effective at low concentration. Our nanosheets spontaneously approached the oil–water interface and reduced the interfacial...

Description: Author(s): P. S. Wang, W. Ren, L. Bellaiche, and H. J. Xiang Multiferroic materials, in which ferroelectric and magnetic ordering coexist, are of practical interest for the development of novel memory devices that allow for electrical writing and nondestructive magnetic readout operation. The great challenge is to create room temperature multiferroic material... [Phys. Rev. Lett. 114, 147204] Published Wed Apr 08, 2015

Description: An ultrathin (subwavelength) hierarchy multi-slit metamaterial with simultaneous negative effective density and negative compressibility is proposed to absorb sound over a wide frequency range. Different from conventional acoustic metamaterials having only negative real parts of acoustic parameters, the imaginary parts of effective density and compressibility are both negative for the proposed metamaterial, which result in superior viscous and thermal dissipation of sound energy. By combining the slit theory of sound absorption with the double porosity theory for porous media, a theoretical model is developed to investigate the sound absorption performance of the metamaterial. To verify the model, a finite element model is established to calculate the effective density, compressibility, and sound absorption of the metamaterial. It is theoretically and numerically confirmed that, upon introducing micro-slits into the meso-slits matrix, the multi-slit metamaterial possesses indeed negative imaginary parts of effective density and compressibility. The influence of micro-slits on the acoustical performance of the metamaterial is analyzed in the context of its specific surface area and static flow resistivity. This work shows great potential of multi-slit metamaterials in noise control applications that require both small volume and small weight of sound-absorbing materials.

Description: In previous work by Gentile Fusillo et al., we developed a selection method for white dwarf candidates which makes use of photometry, colours and proper motions to calculate a probability of being a white dwarf ( P WD ). The application of our method to the Sloan Digital Sky Survey (SDSS) data release 10 resulted in ~=66 000 photometrically selected objects with a derived P WD , approximately ~=21 000 of which are high-confidence white dwarf candidates. Here, we present an independent test of our selection method based on a sample of spectroscopically confirmed white dwarfs from the Large Sky Area Multi-Fiber Spectroscopic Telescope (LAMOST) survey. We do this by cross-matching all our ~=66 000 SDSS photometric white dwarf candidates with the over 4 million spectra available in the third data release of LAMOST. This results in 1673 white dwarf candidates with no previous SDSS spectroscopy, but with available LAMOST spectra. Among these objects, we identify 309 genuine white dwarfs. We find that our P WD can efficiently discriminate between confirmed LAMOST white dwarfs and contaminants. Our white dwarf candidate selection method can be applied to any multiband photometric survey and in this work we conclusively confirm its reliability in selecting white dwarfs without recourse to spectroscopy. We also discuss the spectroscopic completeness of white dwarfs in LAMOST, as well as deriving effective temperatures, surface gravities and masses for the hydrogen-rich atmosphere white dwarfs in the newly identified LAMOST sample.

Description: The formula for maximum efficiency (ηmax) of heat conversion into electricity by a thermoelectric device in terms of the dimensionless figure of merit (ZT) has been widely used to assess the desirability of thermoelectric materials for devices. Unfortunately, the ηmax values vary greatly depending on how the average ZT values...

Description: Author(s): K. A. Avchaciov, W. Ren, F. Djurabekova, K. Nordlund, I. Sveklo, and A. Maziewski We studied the structural modifications of a Pt/Co/Pt trilayer epitaxial film under Ga + 30-keV ion irradiation by means of classical molecular dynamics and Monte Carlo simulations. The semiclassical tight-binding second-moment approximation potential was adjusted to reproduce the enthalpies of forma… [Phys. Rev. B 92, 104109] Published Wed Sep 30, 2015

Description: Next-generation flexible electronics require highly stretchable and transparent electrodes. Few electronic conductors are both transparent and stretchable, and even fewer can be cyclically stretched to a large strain without causing fatigue. Fatigue, which is often an issue of strained materials causing failure at low strain levels of cyclic loading, is...

Description: Stray grains which may appear during production of single-crystal blades, can severely deprave the performance of turbine blades. This investigation primarily explores the conditions of stray grains formed in DZ417G superalloy by using samples with varying cross sections. The effect of withdrawal velocities on the microstructure of DZ417G superalloy in directional solidification is investigated. It is observed that the growth direction of dendrites did not change, and no stray grain appears in the re-entrant corner at low withdrawal velocity. Nevertheless, the stray grains grow up when the withdrawal velocity is higher than 150μm/s. The temperature profiles in the region of the cross section change at different velocities are examined. The increase of undercooling in the corner of the cross section change leads to the formation of stray grains.

Description: The major facilitator superfamily glucose transporters, exemplified by human GLUT1-4, have been central to the study of solute transport. Using lipidic cubic phase crystallization and microfocus X-ray diffraction, we determined the structure of human GLUT3 in complex with D-glucose at 1.5 A resolution in an outward-occluded conformation. The high-resolution structure allows discrimination of both alpha- and beta-anomers of D-glucose. Two additional structures of GLUT3 bound to the exofacial inhibitor maltose were obtained at 2.6 A in the outward-open and 2.4 A in the outward-occluded states. In all three structures, the ligands are predominantly coordinated by polar residues from the carboxy terminal domain. Conformational transition from outward-open to outward-occluded entails a prominent local rearrangement of the extracellular part of transmembrane segment TM7. Comparison of the outward-facing GLUT3 structures with the inward-open GLUT1 provides insights into the alternating access cycle for GLUTs, whereby the C-terminal domain provides the primary substrate-binding site and the amino-terminal domain undergoes rigid-body rotation with respect to the C-terminal domain. Our studies provide an important framework for the mechanistic and kinetic understanding of GLUTs and shed light on structure-guided ligand design.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Deng, Dong -- Sun, Pengcheng -- Yan, Chuangye -- Ke, Meng -- Jiang, Xin -- Xiong, Lei -- Ren, Wenlin -- Hirata, Kunio -- Yamamoto, Masaki -- Fan, Shilong -- Yan, Nieng -- Howard Hughes Medical Institute/ -- England -- Nature. 2015 Oct 15;526(7573):391-6. doi: 10.1038/nature14655. Epub 2015 Jul 15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. ; Center for Structural Biology, Tsinghua University, Beijing 100084, China. ; Tsinghua-Peking Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China. ; Advanced Photon Technology Division, Research Infrastructure Group, SR Life Science Instrumentation Unit, RIKEN/SPring-8 Center, 1-1-1 Kouto Sayo-cho Sayo-gun, Hyogo 679-5148 Japan. ; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26176916" target="_blank"〉PubMed〈/a〉