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Romana Baltic, Marina Pivetta, Fabio Donati, Christian Wäckerlin, Aparajita Singha, Jan Dreiser, Stefano Rusponi, Harald Brune
Regular arrays of single atoms with stable magnetization represent the ultimate limit of ultra-high density storage media. Here we report a self-assembled superlattice of individual and non-interacting Dy atoms on graphene grown on Ir(111), with magnetic hysteresis up to 5.6 T and spin lifetime of 1000 s at 2.5 K. The observed magnetic stability is a consequence of the intrinsic low electron and phonon densities of graphene and the six-fold symmetry of the adsorption site. Our single atom magnet array has a density of 115 Tbit/inch(2)...
October 25, 2016: Nano Letters
Christina Bagwill, Christa Anderson, Elizabeth Sullivan, Varun Manohara, Prithvi Murthy, Charles C Kirkpatrick, Apryll M Stalcup, Michael Adam Lewis
A computational study aimed at accurately predicting the strength of the anion-π binding of substituted benzenes is presented. The anion-π binding energies (Ebind) of 37 substituted benzenes, and the parent benzene, with chloride or bromide were investigated at the MP2(full)/6-311++G** level of theory. In addition, energy decomposition analysis was performed on 27 selected chloride-arene complexes via Symmetry Adapted Perturbation Theory (SAPT), using the SAPT2+ approach. Initial efforts aimed to correlate the anion-π Ebind values with the sum of the Hammett constants σp (Σσp) or σm (Σσm), as done by others...
October 25, 2016: Journal of Physical Chemistry. A
Matthias Wohlgemuth, Roland Mitric
We introduce a general theoretical approach for the simulation of photochemical dynamics under the influence of circularly polarized light in order to explore the possibility of generating enantiomeric enrichment through polarized-light-selective photochemistry. The method is applied to the simulation of the photolysis of alanine, a prototype chiral amino acid. We show that a systematic enantiomeric enrichment can be obtained depending on the helicity of the circularly polarized light that induces the excited state photochemistry of alanine...
October 25, 2016: Journal of Physical Chemistry. A
Jade Taffs, C Patrick Royall
Although long assumed to have an important role in the suppression of crystallization and the development of glassformers, the effect of local fivefold symmetry has never been directly tested. Here we consider whether such suppression of crystallization has a kinetic or thermodynamic nature and investigate its mechanism. We introduce a model in which the degree of fivefold symmetry can be tuned by favouring arrangements of particles in pentagonal bipyramids. We thus show that fivefold symmetry has both kinetic and thermodynamic effects on the mechanism of crystallization to a face-centred cubic crystal...
October 25, 2016: Nature Communications
Zohar A Arnon, Andreas Vitalis, Aviad Levin, Thomas C T Michaels, Amedeo Caflisch, Tuomas P J Knowles, Lihi Adler-Abramovich, Ehud Gazit
The dynamic nature of supramolecular polymers has a key role in their organization. Yet, the manipulation of their dimensions and polarity remains a challenge. Here, the minimalistic diphenylalanine building block was applied to demonstrate control of nano-assemblies growth and shrinkage using microfluidics. To fine-tune differential local environments, peptide nanotubes were confined by micron-scale pillars and subjected to monomer flows of various saturation levels to control assembly and disassembly. The small-volume device allows the rapid adjustment of conditions within the system...
October 25, 2016: Nature Communications
Jörg Peter Pfannmöller, Marvin Greiner, Mukund Balasubramanian, Martin Lotze
The fingertip somatotopy in BA1 and BA3b of monkeys exhibits characteristic differences with a more discrete separation of the body parts in BA3b and a continuous orientation column like structure in BA1. We present evidence for similar differences in the human somatotopy using BOLD fMRI for the investigations. Though the variability between the individual maps was large, we found a group wide somatotopic representation in BA3b and BA1. The variability due to anatomical differences was small in our sample. This was demonstrated by comparing exact shortest distances in the individual brains and after nonlinear normalization to the group space template, for the removal of the individual anatomical variability...
October 21, 2016: Neuroscience
Sella Kim, Ji-Hye Lee, Jong Hyeon Seok, Yi-Ho Park, Sang Won Jung, Art E Cho, Cheolju Lee, Mi Sook Chung, Kyung Hyun Kim
Iron and oxygen chemistry is mediated by iron proteins for many biological functions. Carboxylate-bridged diiron enzymes including ferritin have in common the mechanism of oxygen activation via peroxodiferric intermediates. However, the route for iron uptake and the structural identification of intermediates still remain incomplete. The 4-fold symmetry channel of Helicobacter pylori ferritin (Hpf) was previously proposed as the iron uptake route in eubacteria, but the amino acid residues at the 4-fold channel are not highly conserved...
October 21, 2016: Journal of Molecular Biology
Vladimir Ivanovski, Thomas G Mayerhöfer, Antje Kriltz, Jürgen Popp
Several samples of flat soda-lime silicate glass were investigated by the Infrared Attenuated Total Reflection (IR-ATR) spectroscopy technique. The specular reflectance spectra together with the results of the performed dispersion analysis and the generated reflectance spectra, using Fresnel equations, suggest that the samples are isotropic. In contrast, spectra recorded by the ATR technique suggest an anisotropic structure on the surface of the specimen different from that in the bulk. This is established through differences in the s- and p-polarized IR-ATR spectra, which cannot be simply transformed into one another employing Fresnel formula for an isotropic case...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Yiqian Cui, Junyou Shi, Zili Wang
The centers and radii of radial basis functions (RBFs) greatly affect the approximation capability of RBF networks (RBFNs). Traditional statistics-based approaches are widely used, but they may lack adaptivity to different data structures. Quantum clustering (QC), derived from quantum mechanics and the Schrödinger equation, demonstrates excellent capability in finding the structure and conformity toward data distribution. In this paper, a novel neural networks model called quantum local potential function networks (QLPFNs) is proposed...
October 20, 2016: IEEE Transactions on Neural Networks and Learning Systems
Laurent Pedesseau, Daniel Sapori, Boubacar Traore, Roberto Robles, Hong-Hua Fang, Maria Antonietta Loi, Hsinhan Tsai, Wanyi Nie, Jean-Christophe Blancon, Amanda Neukirch, Sergei Tretiak, Aditya D Mohite, Claudine Katan, Jacky Even, Mikaël Kepenekian
Layered halide hybrid organic-inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells and revisited for light-emitting devices. In this review, we combine classical solid-state physics concepts with simulation tools based on density functional theory to overview the main features of the optoelectronic properties of layered HOP...
October 24, 2016: ACS Nano
Akio Hayashi, Hiromi Ota, Xavier López, Norihito Hiyoshi, Nao Tsunoji, Tsuneji Sano, Masahiro Sadakane
Dipotassium cation (K(+))-encapsulated Preyssler-type phosphotungstate, [P5W30O110K2](13-), was prepared by heating monobismuth (Bi(3+))-encapsulated Preyssler-type phosphotungstate, [P5W30O110Bi(H2O)](12-), in acetate buffer in the presence of an excess amount of potassium cations. Characterization of the isolated potassium salt, K13[P5W30O110K2] (1a), and its acid form, H13[P5W30O110K2] (1b), by single crystal X-ray structure analysis, (31)P and (183)W nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV), high-resolution electrospray ionization mass spectroscopy (HR-ESI-MS), and elemental analysis revealed that two potassium cations are encapsulated in the Preyssler-type phosphotungstate molecule with formal D5h symmetry, which is the first example of a Preyssler-type compound with two encapsulated cations...
October 24, 2016: Inorganic Chemistry
Katarzyna Filipiak, Daniel Klein, Anuradha Roy
The problem of testing the separability of a covariance matrix against an unstructured variance-covariance matrix is studied in the context of multivariate repeated measures data using Rao's score test (RST). The RST statistic is developed with the first component of the separable structure as a first-order autoregressive (AR(1)) correlation matrix or an unstructured (UN) covariance matrix under the assumption of multivariate normality. It is shown that the distribution of the RST statistic under the null hypothesis of any separability does not depend on the true values of the mean or the unstructured components of the separable structure...
October 24, 2016: Biometrical Journal. Biometrische Zeitschrift
Kaichi Yamamoto, Yusuke Kanematsu, Umpei Nagashima, Akira Ueda, Hatsumi Mori, Masanori Tachikawa
κ-H3(Cat-EDT-TTF)2 (H-TTF) is a hydrogen-bonded π-electron system which was found to reveal C2/c symmetry at 50-293 K, while its isotopologue, κ-D3(Cat-EDT-TTF)2 (D-TTF), showed the phase transition at 185 K from C2/c to P1[combining macron]. To elucidate the origin of such a difference, we calculated the potential energy curves (PECs) for the hydrogen transfer along the H-bonds in these conductors. We found that both the π-stacking and the hydrogen nuclear quantum effect drastically affected the hydrogen transfer energy...
October 24, 2016: Physical Chemistry Chemical Physics: PCCP
Francesco Nappi, Cristiano Spadaccio, Antonio Nenna, Mario Lusini, Massimiliano Fraldi, Christophe Acar, Massimo Chello
OBJECTIVE: The symmetry of mitral valve tethering and regional left ventricle wall dysfunction are reported to play a fundamental role in the outcomes and long-term durability of surgical repair in ischemic mitral regurgitation (IMR). We recently demonstrated in a randomized clinical trial (the Papillary Muscle Approximation trial) the superiority of papillary muscle approximation (PMA) in combination with standard restrictive annuloplasty (RA) in severe IMR over annuloplasty alone in terms of adverse left ventricular remodeling and mitral regurgitation (MR) recurrence...
September 24, 2016: Journal of Thoracic and Cardiovascular Surgery
Hana Rakusová, Mohamad Abbas, Huibin Han, Siyuan Song, Hélène S Robert, Jiří Friml
Plants adjust their growth according to gravity. Gravitropism involves gravity perception, signal transduction, and asymmetric growth response, with organ bending as a consequence [1]. Asymmetric growth results from the asymmetric distribution of the plant-specific signaling molecule auxin [2] that is generated by lateral transport, mediated in the hypocotyl predominantly by the auxin transporter PIN-FORMED3 (PIN3) [3-5]. Gravity stimulation polarizes PIN3 to the bottom sides of endodermal cells, correlating with increased auxin accumulation in adjacent tissues at the lower side of the stimulated organ, where auxin induces cell elongation and, hence, organ bending...
October 8, 2016: Current Biology: CB
Andy Tsai, Carol E Barnewolt, Sanjay P Prahbu, Reimi Yonekura, Andrew Hosmer, Noah E Schulz, Peter H Weinstock
RATIONALE AND OBJECTIVES: Historically, skills training in performing brain ultrasonography has been limited to hours of scanning infants for lack of adequate synthetic models or alternatives. The aim of this study was to create a simulator and determine its utility as an educational tool in teaching the skills that can be used in performing brain ultrasonography on infants. MATERIALS AND METHODS: A brain ultrasonography simulator was created using a combination of multi-modality imaging, three-dimensional printing, material and acoustic engineering, and sculpting and molding...
October 20, 2016: Academic Radiology
Filip B J L Stillaert, Casper Sommeling, Salvatore D'Arpa, David Creytens, Koenraad Van Landuyt, Herman Depypere, Rudy Van den Broecke, Stan Monstrey, Phillip N Blondeel, Wayne A Morrison
BACKGROUND: Breast reconstruction involves the use of autologous tissues or implants. Occasionally, microsurgical reconstruction is not an option because of insufficient donor tissues. Fat grafting has become increasingly popular in breast surgery. The challenge with this technique is how to reconstruct a stable and living "scaffold" that resembles a breast. METHODS: Breast reconstruction (n = 7) was performed using intratissular expansion with serial deflation-lipofilling sessions...
September 27, 2016: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
Piotr Stefański
We consider a model of a Josephson junction mediated by a quantum dot. An additional normal electrode coupled to the dot allows its density of states to be probed. The junction is made out of two topological superconducting wires with Majorana end states. The two of them, on each side and in the proximity of the junction, convert into a Dirac fermion inside the dot. It is shown that both the density of states of the dot and the phase-biased current through the junction can exhibit [Formula: see text] periodicity in the superconducting phase difference, when the particle-hole symmetry of the junction is broken...
October 21, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
V L R Jacques, C Laulhé, N Moisan, S Ravy, D Le Bolloc'h
We report on time-resolved x-ray diffraction measurements following femtosecond laser excitation in pure bulk chromium. Comparing the evolution of incommensurate charge-density-wave (CDW) and atomic lattice reflections, we show that, a few nanoseconds after laser excitation, the CDW undergoes different structural changes than the atomic lattice. We give evidence for a transient CDW shear strain that breaks the lattice point symmetry. This strain is characteristic of sliding CDWs, as observed in other incommensurate CDW systems, suggesting the laser-induced CDW sliding capability in 3D systems...
October 7, 2016: Physical Review Letters
Mar Bastero-Gil, Arjun Berera, Rudnei O Ramos, João G Rosa
We show that inflation can naturally occur at a finite temperature T>H that is sustained by dissipative effects, when the inflaton field corresponds to a pseudo Nambu-Goldstone boson of a broken gauge symmetry. Similar to the Little Higgs scenarios for electroweak symmetry breaking, the flatness of the inflaton potential is protected against both quadratic divergences and the leading thermal corrections. We show that, nevertheless, nonlocal dissipative effects are naturally present and are able to sustain a nearly thermal bath of light particles despite the accelerated expansion of the Universe...
October 7, 2016: Physical Review Letters
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