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lattice degeneration

Jing Lu, Guiying Mai, Ruyuan Liu, Yan Luo, Lin Lu
A 63-year-old male presented with a round-shaped floater and visual obscuration in the right eye. Clinical evaluation showed a nonpigmented vitreous cyst connected to a lattice degeneration by a stalk. Immunostaining of the vitreous cyst obtained from vitrectomy showed its origin of retinal neuroepithelium. The cyst was formed by continuous vitreous traction, which might tear up the disrupted retina at the area of lattice degeneration. This report added the lattice degeneration to the list of causes for the acquired vitreous cyst...
October 1, 2017: Ophthalmic Surgery, Lasers & Imaging Retina
S L Campbell, R B Hutson, G E Marti, A Goban, N Darkwah Oppong, R L McNally, L Sonderhouse, J M Robinson, W Zhang, B J Bloom, J Ye
Strontium optical lattice clocks have the potential to simultaneously interrogate millions of atoms with a high spectroscopic quality factor of 4 × 10(17) Previously, atomic interactions have forced a compromise between clock stability, which benefits from a large number of atoms, and accuracy, which suffers from density-dependent frequency shifts. Here we demonstrate a scalable solution that takes advantage of the high, correlated density of a degenerate Fermi gas in a three-dimensional (3D) optical lattice to guard against on-site interaction shifts...
October 6, 2017: Science
Zhe Lü, Jingwei Li, Bo Wei, Zhiqun Cao, Xing Yue, Yaxin Zhang
A novel Nb-doped lanthanum strontium ferrite perovskite oxide La0.8Sr0.2Fe0.9Nb0.1O3-δ (LSFNb) is evaluated as anode material of solid oxide fuel cell (SOFC). The effects of Nb partial substitution on the crystal structure, electrical conductivity and valence of Fe ions are studied. A good structural stability of LSFNb in severe reducing atmosphere at 800 °C is found, suggesting that high valent Nb can effectively promote the stability of lattice structure. The ratio of Fe2+ increases after Nb doping as confirmed by the results of XPS...
October 4, 2017: ChemSusChem
Cyrille Barreteau, Francois Ducastelle, Talal Mallah
We present thorough tight-binding analysis of the band structure of a wide variety of lattices belonging to the class of honeycomb and Kagome systems including several mixed forms combining both lattices. The band structure of these systems are made of a combination of dispersive and flat bands. The dispersive bands possess Dirac cones (linear dispersion) at the six corners (K points) of the Brillouin zone although in peculiar cases Dirac cones at the center of the zone $(\Gamma$ point) appear. The flat bands can be of different nature...
September 29, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Hyeondeok Shin, Jeongnim Kim, Hoonkyung Lee, Olle Heinonen, Anouar Benali, Yongkyung Kwon
α-graphyne is a two-dimensional sheet of sp-sp(2) hybridized carbon atoms in a honeycomb lattice. While the geometrical structure is similar to that of graphene, the hybridized triple bonds give rise to electronic structure that is different from that of graphene. Similar to graphene, α-graphyne can be stacked in bilayers with two stable configurations, but the different stackings have very different electronic structures: one is predicted to have gapless parabolic bands and the other a tunable band gap which is attractive for applications...
September 25, 2017: Journal of Chemical Theory and Computation
Matthieu David, Damien Connetable
While diffusion mechanisms of interstitial elements in fcc systems are generally well-known, especially in the case of H atoms, we show in this work that even in the case of a simple metallic system (aluminum), the diffusion of interstitials exhibits a wide variety of paths and mechanisms that depend on the specie. We used an approach based on first-principles calculations associated with kinetic Monte-Carlo simulations and a multi-state diffusion formalism to compute the diffusion coefficients of five interstitial elements: hydrogen, boron, carbon, nitrogen and oxygen...
September 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Raj K Vinnakota, Dentcho A Genov
We present an optoelectronic switch for functional plasmonic circuits based on active control of Surface Plasmon Polaritons (SPPs) at degenerate PN(+)-junction interfaces. Self-consistent multi-physics simulations of the electromagnetic, thermal and IV characteristics of the device have been performed. The lattice matched Indium Gallium Arsenide (In0.53Ga0.47As) is identified as a better semiconductor material compared to Si for the practical implementation of the proposed optoelectronic switch providing higher optical confinement, reduced size and faster operation...
September 7, 2017: Scientific Reports
Jung-Wan Ryu, Nojoon Myoung, Hee Chul Park
We demonstrate mesoscopic transport through quantum states in quasi-1D lattices maintaining the combination of parity and time-reversal symmetries by controlling energy gain and loss. We investigate the phase diagram of the non-Hermitian system where transitions take place between unbroken and broken [Formula: see text]-symmetric phases via exceptional points. Quantum transport in the lattice is measured only in the unbroken phases in the energy band-but not in the broken phases. The broken phase allows for spontaneous symmetry-broken states where the cross-stitch lattice is separated into two identical single lattices corresponding to conditionally degenerate eigenstates...
August 18, 2017: Scientific Reports
M Sacchi, P Singh, D M Chisnall, D J Ward, A P Jardine, W Allison, J Ellis, H Hedgeland
We use helium spin-echo spectroscopy (HeSE) to investigate the dynamics of the diffusion of benzene adsorbed on Cu(111). The results of these measurements show that benzene moves on the surface through an activated jump-diffusion process between the adsorption sites on a Bravais lattice. Density Functional Theory (DFT) calculations with van der Waals (vdW) corrections help us understand that the molecule diffuses by jumping through non-degenerate hollow sites. The results of the calculations shed light on the nature of the binding interaction between this prototypical aromatic molecule and the metallic surface...
August 2, 2017: Faraday Discussions
Nicolas A Yannuzzi, Jonathan S Chang, Gary C Brown, William E Smiddy
PURPOSE: To evaluate the costs and cost-utility of examination for posterior vitreous detachment (PVD) and treatment of associated pathology, and of managing various other peripheral retinal disorders to prevent retinal detachment (RD). DESIGN: A decision analysis model of cost-utility. PARTICIPANTS: There were no participants. METHODS: Published retrospective data on the natural course of PVD, retinal tears, and lattice degeneration were used to quantitate the visual benefits of examination and treatment...
July 18, 2017: Ophthalmology
Wenjian Hu, Rajiv R P Singh, Richard T Scalettar
We apply unsupervised machine learning techniques, mainly principal component analysis (PCA), to compare and contrast the phase behavior and phase transitions in several classical spin models-the square- and triangular-lattice Ising models, the Blume-Capel model, a highly degenerate biquadratic-exchange spin-1 Ising (BSI) model, and the two-dimensional XY model-and we examine critically what machine learning is teaching us. We find that quantified principal components from PCA not only allow the exploration of different phases and symmetry-breaking, but they can distinguish phase-transition types and locate critical points...
June 2017: Physical Review. E
Xi-Wang Luo, Xingxiang Zhou, Jin-Shi Xu, Chuan-Feng Li, Guang-Can Guo, Chuanwei Zhang, Zheng-Wei Zhou
All-optical photonic devices are crucial for many important photonic technologies and applications, ranging from optical communication to quantum information processing. Conventional design of all-optical devices is based on photon propagation and interference in real space, which may rely on large numbers of optical elements, and the requirement of precise control makes this approach challenging. Here we propose an unconventional route for engineering all-optical devices using the photon's internal degrees of freedom, which form photonic crystals in such synthetic dimensions for photon propagation and interference...
July 14, 2017: Nature Communications
Giles Kagmeni, Georges Nguefack-Tsague, Steve Robert Ebana Mvogo, Come Ebana Mvogo
BACKGROUND: The purpose of this prospective, noncomparative consecutive study was to examine active and retired amateur boxers in order to evaluate the nature and incidence of ocular pathologic conditions related to the boxing practice. RESULTS: A total of 35 boxers were included in this study. The mean age of the boxers was 28.09±7.57 years (range 18-52 years). Sixteen (45.7%) boxers had >5 years of boxing experience. Fifteen (42.85%) of the boxers reported wearing protective equipment in the bouts and sparring rounds...
2017: Clinical Ophthalmology
Chengyong Zhong, Yuanping Chen, Zhi-Ming Yu, Yuee Xie, Han Wang, Shengyuan A Yang, Shengbai Zhang
Carbon, the basic building block of our universe, enjoys a vast number of allotropic structures. Owing to its bonding characteristic, most carbon allotropes possess the motif of hexagonal rings. Here, with first-principles calculations, we discover a new metastable three-dimensional carbon allotrope entirely composed of pentagon rings. The unique structure of this Pentagon Carbon leads to extraordinary electronic properties, making it a cornucopia of emergent topological fermions. Under lattice strain, Pentagon Carbon exhibits topological phase transitions, generating a series of novel quasiparticles, from isospin-1 triplet fermions to triply degenerate fermions and further to Hopf-link Weyl-loop fermions...
June 5, 2017: Nature Communications
Sera Kim, Seunghyun Song, Jongho Park, Ho Sung Yu, Suyeon Cho, Dohyun Kim, Jaeyoon Baik, Duk-Hyun Choe, K J Chang, Young Hee Lee, Sung Wng Kim, Heejun Yang
Doping two-dimensional (2D) semiconductors beyond their degenerate levels provides the opportunity to investigate extreme carrier density-driven superconductivity and phase transition in 2D systems. Chemical functionalization and the ionic gating have achieved the high doping density, but their effective ranges have been limited to ∼1 nm, which restricts the use of highly doped 2D semiconductors. Here, we report on electron diffusion from the 2D electride [Ca2N](+)·e(-) to MoTe2 over a distance of 100 nm from the contact interface, generating an electron doping density higher than 1...
June 14, 2017: Nano Letters
Arjun Kalra, Patrick Tishmack, Joseph W Lubach, Eric J Munson, Lynne S Taylor, Stephen R Byrn, Tonglei Li
Despite numerous challenges in their theoretical description and practical implementation, amorphous drugs are of growing importance to the pharmaceutical industry. One such challenge is to gain molecular level understanding of the propensity of a molecule to form and remain as a glassy solid. In this study, a series of structurally similar diarylamine compounds was examined to elucidate the role of supramolecular aggregation on crystallization kinetics from supercooled liquid state. The structural similarity of the compounds makes it easier to isolate the molecular features that affect crystallization kinetics and glass forming ability of these compounds...
May 17, 2017: Molecular Pharmaceutics
Jing-Kai Qin, Wen-Zhu Shao, Cheng-Yan Xu, Yang Li, Dan-Dan Ren, Xiao-Guo Song, Liang Zhen
Substitutional doping of transition metal dichalcogenide two-dimensional materials has proven to be effective in tuning their intrinsic properties, such as band gap, transport characteristics, and magnetism. In this study, we realized substitutional doping of monolayer rhenium disulfide (ReS2) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS2 field effect transistors, in agreement with density functional theory calculations...
May 1, 2017: ACS Applied Materials & Interfaces
M Schmidt, F M Zimmer, S G Magalhaes
The interplay between geometric frustration (GF) and bond disorder is studied in the Ising kagome lattice within a cluster approach. The model considers antiferromagnetic short-range couplings and long-range intercluster disordered interactions. The replica formalism is used to obtain an effective single cluster model from where the thermodynamics is analyzed by exact diagonalization. We found that the presence of GF can introduce cluster freezing at very low levels of disorder. The system exhibits an entropy plateau followed by a large entropy drop close to the freezing temperature...
April 26, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Kyounghwan Kim, Ashley DaSilva, Shengqiang Huang, Babak Fallahazad, Stefano Larentis, Takashi Taniguchi, Kenji Watanabe, Brian J LeRoy, Allan H MacDonald, Emanuel Tutuc
According to electronic structure theory, bilayer graphene is expected to have anomalous electronic properties when it has long-period moiré patterns produced by small misalignments between its individual layer honeycomb lattices. We have realized bilayer graphene moiré crystals with accurately controlled twist angles smaller than 1° and studied their properties using scanning probe microscopy and electron transport. We observe conductivity minima at charge neutrality, satellite gaps that appear at anomalous carrier densities for twist angles smaller than 1°, and tunneling densities-of-states that are strongly dependent on carrier density...
March 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
Long Zhang, Fa Wang
A symmetry-protected topological phase has nontrivial surface states in the presence of certain symmetries, which can either be gapless or be degenerate. In this work, we study the physical consequence of such gapless surface states at the bulk quantum phase transition (QPT) that spontaneously breaks these symmetries. The two-dimensional Affleck-Kennedy-Lieb-Tasaki phase on a square lattice and its QPTs to Néel ordered phases are realized with the spin-1/2 Heisenberg model on a decorated square lattice. With large-scale quantum Monte Carlo simulations, we show that even though the bulk QPTs are governed by the conventional Landau phase transition theory, the gapless surface states induce unconventional universality classes of the surface critical behavior...
February 24, 2017: Physical Review Letters
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