bluuebunny/crossref_metadata_2025 huggingface dataset:
Myocardial Tissue Characterization: Histological and Pathophysiological Correlation
Authors: Treibel T. A. , White S. K. , Moon J. C.
Published: January 2014

Cardiovascular magnetic resonance imaging (CMR) has become the gold standard not only for cardiac volume and function quantification, but for a key unique strength: non-invasive myocardial tissue characterization. Several different techniques, separately or in combination, can detect and quantify early and established myocardial pathological processes permitting better diagnosis, prognostication and tracking of therapy. The authors will focus on the histological and pathophysiological evidence of these imaging parameters in the characterization of edema, infarction, scar and fibrosis. In addition to laying out the strengths and weaknesses of each modality, the reader will be introduced to rapid developments in T1 and T2 mapping as well as the use of contrast-derived extracellular volume for quantification of diffuse fibrosis.
Connexin hemichannel and pannexin channel electrophysiology: How do they differ?
Authors: Patel Dakshesh , Zhang Xian , Veenstra Richard D.
Published: January 2014

Connexin hemichannels are postulated to form a cell permeabilization pore for the uptake of fluorescent dyes and release of cellular ATP. Connexin hemichannel activity is enhanced by low external [Ca2+]o, membrane depolarization, metabolic inhibition, and some disease‐causing gain‐of‐function connexin mutations. This paper briefly reviews the electrophysiological channel conductance, permeability, and pharmacology properties of connexin hemichannels, pannexin 1 channels, and purinergic P2X7 receptor channels as studied in exogenous expression systems including Xenopus oocytes and mammalian cell lines such as HEK293 cells. Overlapping pharmacological inhibitory and channel conductance and permeability profiles makes distinguishing between these channel types sometimes difficult. Selective pharmacology for Cx43 hemichannels (Gap19 peptide), probenecid or FD&C Blue #1 (Brilliant Blue FCF, BB FCF) for Panx1, and A740003, A438079, or oxidized ATP (oATP) for P2X7 channels may be the best way to distinguish between these three cell permeabilizing channel types. Endogenous connexin, pannexin, and P2X7 expression should be considered when performing exogenous cellular expression channel studies. Cell pair electrophysiological assays permit the relative assessment of the connexin hemichannel/gap junction channel ratio not often considered when performing isolated cell hemichannel studies.
Ablation on the mitral annulus for the treatment of atrial fibrillation: Anatomical consideration to prevent coronary injury
Authors: Imura Hajime , Hames Kiyomi Y. , Miyagi Yasuo , Murata Hiroshige , Nitta Takashi , Ochi Masami
Published: January 2014

Coronary injury is a crucial complication of ablation on the posterior mitral annulus (PMA). Fifty autopsy heart specimens were classified into different types according to the final branch of the left circumflex coronary artery. The no‐coronary area on the PMA was examined in each type. The posterolateral type was most common (39/50); the no‐coronary area was located between 50.7%±6.5% and 83.5%±8.0% on the PMA. Ablations at 38.6%±5.2% (for catheter intervention) and the middle point (for surgery) appear safe for the obtuse marginal type but not for the posterolateral type. Thus, the no‐coronary area should be considered during PMA ablation.
Paradoxical undersensing of atrial electrograms during atrial fibrillation due to repeated activation of the quiet timer blanking interval: Case report and review of the literature
Authors: Morishima Itsuro , Sone Takahito , Takami Mitsuaki , Tsuboi Hideyuki , Michitaka Uesugi , Matsushita Etsushi , Morita Yasuhiro , Tsuji Yoshinori
Published: January 2014

This report describes a case of paradoxical atrial undersensing by a dual‐chamber pacemaker during paroxysmal atrial fibrillation. Undersensing of 5.6 mV atrial signals at a programmed sensitivity of 0.5 mV returned to normal sensing by decreasing atrial sensitivity to 1.0 mV. This uncommon phenomenon can be explained by a repeated activation of the quiet timer blanking interval. Knowledge of this phenomenon is important in the current pacemaker management to improve the accuracy of the diagnostic feature for atrial tachyarrhythmia burden and to avoid unnecessary lead revisions.
National Estimates of Noncanine Bite and Sting Injuries Treated in US Hospital Emergency Departments, 2001–2010
Authors: Langley Ricky , Mack Karin , Haileyesus Tadesse , Proescholdbell Scott , Annest Joseph L.
Published: January 2014

Objective

Injuries resulting from contact with animals and insects are a significant public health concern. This study quantifies nonfatal bite and sting injuries by noncanine sources using data from the National Electronic Injury Surveillance System–All Injury Program (NEISS-AIP).

Methods

The NEISS-AIP is an ongoing nationally representative surveillance system used to monitor all types and causes of injuries treated in US hospital emergency departments (EDs). Cases were coded by trained hospital coders using information from medical records on animal and insect sources of bite and sting injuries being treated. Data were weighted to produce national annualized estimates, percentages, and rates based on the US population.

Results

From 2001 to 2010 an estimated 10.1 million people visited EDs for noncanine bite and sting injuries, based on an unweighted case count of 169,010. This translates to a rate of 340.1 per 100,000 people (95% CI, 232.9–447.3). Insects accounted for 67.5% (95% CI, 45.8–89.2) of bite and sting injuries, followed by arachnids 20.8% (95% CI, 13.8–27.9). The estimated number of ED visits for bedbug bite injuries increased more than 7-fold—from 2156 visits in 2007 to 15,945 visits in 2010.

Conclusions

This study provides an update of national estimates of noncanine bite and sting injuries and describes the diversity of animal exposures based on a national sample of EDs. Treatment of nonfatal bite and sting injuries are costly to society. Direct medical and work time lost translates to an estimated $7.5 billion annually.
Studies on the growth of marine phytoplankton II. Isochrysis galbana Parke
Authors: Kain Joanna M. , Fogg G. E.
Published: January 2014

A good deal is known about the growth in culture of Phaeodactylum tricornutum Bohlin (Nitzschia closterium W. Sm. forma minutissima Allen & Nelson) (see Spencer, 1954; Harvey, 1955; Provasoli, McLaughlin & Droop, 1957). This organism, however, is a somewhat aberrant member of the Chrysophyta, and other marine and brackish-water representatives of the group, e.g. Syracosphaera carterae Braarud & Fagerland (Braarud & Fagerland, 1946; Provasoli, McLaughlin & Pintner, 1954), Prymnesium parvum Carter (Reich & Kahn, 1954; Droop, 1954), and certain other species (Droop, 1954, 1955 a, b) have been studied much less intensively from this point of view. It has therefore seemed worth while making a general study, similar to that reported in the first paper of this series for the diatom Asterionella japonica Cleve & Müller ex Gran, of the growth requirements of a representative of the Chrysophyceae. Isochrysis galbana Parke, a flagellate of some importance as a food organism of the oyster, has been selected for this purpose. Johnston (1955) has used unialgal cultures of this species in studies of dissolved organic matter in sea water and, since the investigation being described was carried out, Droop (1957) has reported that it has a requirement for cobalamin.
Taking Two-Photon Excitation (2PE) further: 2PE coupling to Far-field Optical Nanoscopy and Super Resolution Microscopy towards Three-dimensional (3D) Imaging of Thick Scattering Specimens
Authors: Diaspro A. , Bianchini P. , Cella Zanacchi F. , Vicidomini G. , Harke B. , Galiani S. , Chacko J. , Coto I. , Lavagnino Z. , d'Amora M.
Published: January 2014

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
Electron Holography of Dipolar Magnetism in Self-assembled Nanoparticle Chains
Authors: Beleggia M. , Varon M. , Kasama T. , Dunin-Borkowski R.E. , Puntes V.F. , Harrison R.J. , Frandsen C.
Published: January 2014

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
Swansong biospheres II: the final signs of life on terrestrial planets near the end of their habitable lifetimes
Authors: O'Malley-James Jack T. , Cockell Charles S. , Greaves Jane S. , Raven John A.
Published: January 2014

The biosignatures of life on Earth do not remain static, but change considerably over the planet's habitable lifetime. Earth's future biosphere, much like that of the early Earth, will consist of predominantly unicellular microorganisms due to the increased hostility of environmental conditions caused by the Sun as it enters the late stage of its main sequence evolution. Building on previous work, the productivity of the biosphere is evaluated during different stages of biosphere decline between 1 and 2.8 Gyr from present. A simple atmosphere–biosphere interaction model is used to estimate the atmospheric biomarker gas abundances at each stage and to assess the likelihood of remotely detecting the presence of life in low-productivity, microbial biospheres, putting an upper limit on the lifetime of Earth's remotely detectable biosignatures. Other potential biosignatures such as leaf reflectance and cloud cover are discussed.
Runaway greenhouse effect on exomoons due to irradiation from hot, young giant planets
Authors: Heller R. , Barnes R.
Published: January 2014

The Kepler space telescope has proven capable of detecting transits of objects almost as small as the Earth's Moon. Some studies suggest that moons as small as 0.2 Earth masses can be detected in the Kepler data by transit timing variations and transit duration variations of their host planets. If such massive moons exist around giant planets in the stellar habitable zone (HZ), then they could serve as habitats for extraterrestrial life. While earlier studies on exomoon habitability assumed the host planet to be in thermal equilibrium with the absorbed stellar flux, we here extend this concept by including the planetary luminosity from evolutionary shrinking. Our aim is to assess the danger of exomoons to be in a runaway greenhouse state due to extensive heating from the planet. We apply pre-computed evolution tracks for giant planets to calculate the incident planetary radiation on the moon as a function of time. Added to the stellar flux, the total illumination yields constraints on a moon's habitability. Ultimately, we include tidal heating to evaluate a moon's energy budget. We use a semi-analytical formula to parameterize the critical flux for the moon to experience a runaway greenhouse effect. Planetary illumination from a 13-Jupiter-mass planet onto an Earth-sized moon at a distance of ten Jupiter radii can drive a runaway greenhouse state on the moon for about 200 million years (Myr). When stellar illumination equivalent to that received by Earth from the Sun is added, then the runaway greenhouse holds for about 500 Myr. After 1000 Myr, the planet's habitable edge has moved inward to about six Jupiter radii. Exomoons in orbits with eccentricities of 0.1 experience strong tidal heating; they must orbit a 13-Jupiter-mass host beyond 29 or 18 Jupiter radii after 100 Myr (at the inner and outer boundaries of the stellar HZ, respectively), and beyond 13 Jupiter radii (in both cases) after 1000 Myr to be habitable. If a roughly Earth-sized, Earth-mass moon would be detected in orbit around a giant planet, and if the planet–moon duet would orbit in the stellar HZ, then it will be crucial to recover the orbital history of the moon. If, for example, such a moon around a 13-Jupiter-mass planet has been closer than 20 Jupiter radii to its host during the first few hundred million years at least, then it might have lost substantial amounts of its initial water reservoir and be uninhabitable today.
Electrostatic activation of prebiotic chemistry in substellar atmospheres
Authors: Stark C. R. , Helling Ch. , Diver D. A. , Rimmer P. B.
Published: January 2014

Charged dust grains in the atmospheres of exoplanets may play a key role in the formation of prebiotic molecules, necessary to the origin of life. Dust grains submerged in an atmospheric plasma become negatively charged and attract a flux of ions that are accelerated from the plasma. The energy of the ions upon reaching the grain surface may be sufficient to overcome the activation energy of particular chemical reactions that would be unattainable via ion and neutral bombardment from classical, thermal excitation. As a result, prebiotic molecules or their precursors could be synthesized on the surface of dust grains that form clouds in exoplanetary atmospheres. This paper investigates the energization of the plasma ions, and the dependence on the plasma electron temperature, in the atmospheres of substellar objects such as gas giant planets. Calculations show that modest electron temperatures of ≈1 eV (≈104 K) are enough to accelerate ions to sufficient energies that exceed the activation energies required for the formation of formaldehyde, ammonia, hydrogen cyanide and the amino acid glycine.
Stolen Twin: Fascination and Curiosity/Twin Research Reports: Evolution of Sleep Length; Dental Treatment of Craniopagus Twins; Cryopreserved Double Embryo Transfer; Gender Options in Multiple Pregnancy/Current Events: Appendectomy in One Twin; Autistic Twin Marathon Runners; 3D Facial Recognition; Twin Biathletes
Authors: Segal Nancy L.
Published: January 2014

The story of her allegedly stolen twin brother in Armenia is recounted by a ‘singleton twin’ living in the United States. The behavioral consequences and societal implications of this loss are considered. This case is followed by twin research reports on the evolution of sleep length, dental treatment of craniopagus conjoined twins, cryopreserved double embryo transfer (DET), and gender options in multiple pregnancy. Current events include the diagnosis of appendectomy in one identical twin, the accomplishments of autistic twin marathon runners, the power of three-dimensional (3D) facial recognition, and the goals of twin biathletes heading to the 2014 Sochi Olympics in Russia.
Highly stable colorimetric aptamer sensors for detection of ochratoxin A through optimizing the sequence with the covalent conjugation of hemin
Authors: Lee Jayeon , Jeon Chang Hoon , Ahn Sang Jung , Ha Tai Hwan
Published: January 2014

Optimization of hairpin DNA is introduced to detect ochratoxin A (OTA) by chemically conjugating its cofactor, hemin, toward the 5′-end.
Fine tuning of crystal architecture by intermolecular interactions: synthon engineering
Authors: Bombicz Petra , Gruber Tobias , Fischer Conrad , Weber Edwin , Kálmán Alajos
Published: January 2014

The term “synthon engineering” is introduced for the directed manipulation of the molecular packing architecture including the system of secondary interactions caused by the respectively fine tuned synthons.
Assembly-mediated interplay of dipolar interactions and surface spin disorder in colloidal maghemite nanoclusters
Authors: Kostopoulou A. , Brintakis K. , Vasilakaki M. , Trohidou K. N. , Douvalis A. P. , Lascialfari A. , Manna L. , Lappas A.
Published: January 2014

Dynamical susceptibility and Monte Carlo simulations unravel the spin-glass dynamics due to the assembly of colloidal nanoparticles in clusters with increased volume fraction.
Iodeosin-based fluorescent and colorimetric sensing for Ag+, Hg2+, Fe3+, and further for halide ions in aqueous solution
Authors: Wang Meiling , Meng Guowen , Huang Qing
Published: January 2014

We report that common erythrosin B can be used as a dual-mode fluorescent and colorimetric sensor for Ag+, Hg2+ and Fe3+, and further for halide ions in aqueous solution based on erythrosin B complexation with the three metal ions.
Asymmetric synthesis of chiral cycloalkenone derivatives via palladium catalysis
Authors: Trost Barry M. , Masters James T. , Lumb Jean-Philip , Fateen Dahlia
Published: January 2014

Palladium-catalyzed oxidative desymmetrization enables the efficient synthesis of both enantioenriched cycloalkenone building blocks and diverse epoxyquinoid natural products.
Fe2O3@SnO2 nanoparticle decorated graphene flexible films as high-performance anode materials for lithium-ion batteries
Authors: Liu Shuo , Wang Ronghua , Liu Miaomiao , Luo Jianqiang , Jin Xihai , Sun Jing , Gao Lian
Published: January 2014

A flexible graphene film decorated with spindle-like Fe2O3@SnO2 nanoparticles was fabricated through vacuum filtration of Fe2O3@SnO2 and GO mixing solution, followed by thermal reduction.
A ZnO nanorod/nanoparticle hierarchical structure synthesized through a facile in situ method for dye-sensitized solar cells
Authors: Gao Rui , Cui Yixiu , Liu Xiaojiang , Wang Liduo , Cao Guozhong
Published: January 2014

Nanorods/nanoparticles hierarchically structured on a ZnO foil were fabricated by a facile method as flexible photoanodes with a significantly improved performance.
Lys11- and Lys48-linked ubiquitin chains interact with p97 during endoplasmic-reticulum-associated degradation
Authors: Locke Matthew , Toth Julia I. , Petroski Matthew D.
Published: January 2014

The ATPase associated with various cellular activities p97 has a critical function in the cytoplasmic degradation of proteins misfolded in the ER (endoplasmic reticulum) through a mechanism known as ERAD (ER-associated degradation). During this process, p97 binds polyubiquitinated ERAD substrates and couples ATP hydrolysis to their dislocation from the ER as a prerequisite to destruction by the proteasome. The ubiquitin signals important for this process are not fully understood. In the present paper we report that p97 interacts with Lys11- and Lys48-linked ubiquitin polymers, but not those containing Lys63 linkages. Disruption of p97 through siRNA-mediated depletion, dominant-negative overexpression or chemical inhibition results in the accumulation of Lys11 and Lys48 ubiquitin chains predominantly at the ER membrane, and is associated with ER stress induction. We show that a catalytically inactive deubiquitinating enzyme and p97 cofactor YOD1 enhances the accumulation of Lys11- and Lys48-linked polyubiquitin in the cytoplasm, at the ER membrane and bound to p97. In addition to general effects on p97-associated ubiquitin polymers, the ERAD substrate CD3δ is modified with both Lys11 and Lys48 ubiquitin chains prior to p97-dependent dislocation. Collectively, the results of the present study are consistent with a major role for p97 in the recognition of Lys11 and Lys48 polyubiquitinated proteins before their degradation by the proteasome.
Scene‐based pedestrian safety performance model in mixed traffic situation
Authors: Zhang Yingying , Yao Danya , Qiu Tony Z. , Peng Lihui
Published: January 2014

Compared to vehicle‐only collisions, traffic collisions with pedestrians are studied less because of insufficient data. However, with the development of image processing technology, a growing number of road user behavioural analyses have been conducted using video data. This study tries to extract road users’ movements from video data in order to analyse the conflict between pedestrian and vehicle and to evaluate pedestrian safety performance during conflicts. The time difference to collision (TDTC) parameter is used to fit the safety analysis on pedestrian‐involved conflicts. Scene‐based analysis, which evaluates the safety performance of traffic intersections and segments where several pedestrian–vehicle conflicts may happen together, is conducted using 91 groups of scene data. The parameters most related to pedestrian safety are located using a sensitivity test, a quantitative definition of pedestrian–vehicle conflict is then defined, and a scene‐based pedestrian safety performance evaluation model is built. The model can correctly detect nearly 94.4% of possibly dangerous traffic scenes. Other kinds of mixed traffic scenes can also be studied based on this research.
Investigation of longitudinal proton acceleration in exploded targets irradiated by intense short-pulse laser
Authors: Gauthier M. , Lévy A. , d'Humières E. , Glesser M. , Albertazzi B. , Beaucourt C. , Breil J. , Chen S. N. , Dervieux V. , Feugeas J. L. , Nicolaï P. , Tikhonchuk V. , Pépin H. , Antici P. , Fuchs J.
Published: January 2014

It was recently shown that a promising way to accelerate protons in the forward direction to high energies is to use under-dense or near-critical density targets instead of solids. Simulations have revealed that the acceleration process depends on the density gradients of the plasma target. Indeed, under certain conditions, the most energetic protons are predicted to be accelerated by a collisionless shock mechanism that significantly increases their energy. We report here the results of a recent experiment dedicated to the study of longitudinal ion acceleration in partially exploded foils using a high intensity (∼5 × 1018 W/cm2) picosecond laser pulse. We show that protons accelerated using targets having moderate front and rear plasma gradients (up to ∼8 μm gradient length) exhibit similar maximum proton energy and number compared to proton beams that are produced, in similar laser conditions, from solid targets, in the well-known target normal sheath acceleration regime. Particle-In-Cell simulations, performed in the same conditions as the experiment and consistent with the measurements, allow laying a path for further improvement of this acceleration scheme.
Room temperature single-photon detectors for high bit rate quantum key distribution
Authors: Comandar L. C. , Fröhlich B. , Lucamarini M. , Patel K. A. , Sharpe A. W. , Dynes J. F. , Yuan Z. L. , Penty R. V. , Shields A. J.
Published: January 2014

We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.
Density functional theory and evolution algorithm calculations of elastic properties of AlON
Authors: Batyrev I. G. , Taylor D. E. , Gazonas G. A. , McCauley J. W.
Published: January 2014

Different models for aluminum oxynitride (AlON) were calculated using density functional theory and optimized using an evolutionary algorithm. Evolutionary algorithm and density functional theory (DFT) calculations starting from several models of AlON with different Al or O vacancy locations and different positions for the N atoms relative to the vacancy were carried out. The results show that the constant anion model [McCauley et al., J. Eur. Ceram. Soc. 29(2), 223 (2009)] with a random distribution of N atoms not adjacent to the Al vacancy has the lowest energy configuration. The lowest energy structure is in a reasonable agreement with experimental X-ray diffraction spectra. The optimized structure of a 55 atom unit cell was used to construct 220 and 440 atom models for simulation cells using DFT with a Gaussian basis set. Cubic elastic constant predictions were found to approach the experimentally determined AlON single crystal elastic constants as the model size increased from 55 to 440 atoms. The pressure dependence of the elastic constants found from simulated stress-strain relations were in overall agreement with experimental measurements of polycrystalline and single crystal AlON. Calculated IR intensity and Raman spectra are compared with available experimental data.
Protein detection with magnetic nanoparticles in a rotating magnetic field
Authors: Dieckhoff Jan , Lak Aidin , Schilling Meinhard , Ludwig Frank
Published: January 2014

A detection scheme based on magnetic nanoparticle (MNP) dynamics in a rotating magnetic field for a quantitative and easy-to-perform detection of proteins is illustrated. For the measurements, a fluxgate-based setup was applied, which measures the MNP dynamics, while a rotating magnetic field is generated. The MNPs exhibit single iron oxide cores of 25 nm and 40 nm diameter, respectively, as well as a protein G functionalized shell. IgG antibodies were utilized as binding target molecules for the physical proof-of-concept. The measurement results were fitted with a theoretical model describing the magnetization dynamics in a rotating magnetic field. The established detection scheme allows quantitative determination of proteins even at a concentration lower than of the particles. The observed differences between the two MNP types are discussed on the basis of logistic functions.
Lattice location and thermal stability of implanted nickel in silicon studied by on-line emission channeling
Authors: Silva D. J. , Wahl U. , Correia J. G. , Pereira L. M. C. , Amorim L. M. , da Silva M. R. , Bosne E. , Araújo J. P.
Published: January 2014

We have studied the lattice location of implanted nickel in silicon, for different doping types (n, n+, and p+). By means of on-line emission channeling, 65Ni was identified on three different sites of the diamond lattice: ideal substitutional sites, displaced bond-center towards substitutional sites (near-BC), and displaced tetrahedral interstitial towards anti-bonding sites (near-T). We suggest that the large majority of the observed lattice sites are not related to the isolated form of Ni but rather to its trapping into vacancy-related defects produced during the implantation. While near-BC sites are prominent after annealing up to 300–500 °C, near-T sites are preferred after 500–600 °C anneals. Long-range diffusion starts at 600–700 °C. We show evidence of Ni diffusion towards the surface and its further trapping on near-T sites at the Rp/2 region, providing a clear picture of the microscopic mechanism of Ni gettering by vacancy-type defects. The high thermal stability of near-BC sites in n+-type Si, and its importance for the understanding of P-diffusion gettering are also discussed.
HfO2 based memory devices with rectifying capabilities
Authors: Quinteros C. , Zazpe R. , Marlasca F. G. , Golmar F. , Casanova F. , Stoliar P. , Hueso L. , Levy P.
Published: January 2014

We report on the fabrication and characterization of metal/insulator/metal capacitor like devices, with both rectifying and hysteretic features. Devices are formed by two junctions, Ti/HfO2 and Co/HfO2. Each junction exhibits highly repetitive hysteretic I-V curves with a sharp transition from a high to a low resistance state (3–4 orders of magnitude jump). The opposite transition (from low to high) is induced by polarity reversal. The rectifying non-crossing characteristics of the I-V branches denote their potential use as a multifunctional device, acting as a built-in rectifier and memory cell in a single device. Based on the phenomenological model description by Zazpe et al. [Appl. Phys. Lett. 103, 073114 (2013)], we propose a circuital equivalent representation supported on switchable rectifying junctions. By exploring different electrode connections, we disentangle the role of the bulk transport in HfO2 devices.
Anomalous behaviour of magnetic coercivity in graphene oxide and reduced graphene oxide
Authors: Bagani K. , Bhattacharya A. , Kaur J. , Rai Chowdhury A. , Ghosh B. , Sardar M. , Banerjee S.
Published: January 2014

In this report, we present the temperature dependence of the magnetic coercivity of graphene oxide (GO) and reduced graphene oxide (RGO). We observe an anomalous decrease in coercivity of GO and RGO with decreasing temperature. The observation could be understood by invoking the inherent presence of wrinkles on graphene oxide due to presence of oxygen containing groups. Scanning electron microscopic image reveals high wrinkles in GO than RGO. We observe higher coercivity in RGO than in GO. At room temperature, we observe antiferromagnetic and ferromagnetic behaviours in GO and RGO, respectively. Whereas, at low temperatures (below T = 60–70 K), both materials show paramagnetic behaviour.
An improved model electronic Hamiltonian for potential energy surfaces and spin−orbit couplings of low-lying d−d states of [Fe(bpy)3]2+
Authors: Iuchi Satoru , Koga Nobuaki
Published: January 2014

With the aim of exploring excited state dynamics, a model electronic Hamiltonian for several low-lying d−d states of [Fe(bpy)3]2+ complex [S. Iuchi, J. Chem. Phys. 136, 064519 (2012)] is refined using density-functional theory calculations of singlet, triplet, and quintet states as benchmarks. Spin−orbit coupling elements are also evaluated within the framework of the model Hamiltonian. The accuracy of the developed model Hamiltonian is determined by examining potential energies and spin−orbit couplings at surface crossing regions between different spin states. Insights into the potential energy surfaces around surface crossing regions are also provided through molecular dynamics simulations. The results demonstrate that the constructed model Hamiltonian can be used for studies on the d−d excited state dynamics of [Fe(bpy)3]2+.
The effect of guide-field and boundary conditions on collisionless magnetic reconnection in a stressed X-point collapse
Authors: Graf von der Pahlen J. , Tsiklauri D.
Published: January 2014

Works of Tsiklauri and Haruki [Phys. Plasmas 15, 102902 (2008); 14, 112905 (2007)] are extended by inclusion of the out-of-plane magnetic (guide) field. In particular, magnetic reconnection during collisionless, stressed X-point collapse for varying out-of-plane guide-fields is studied using a kinetic, 2.5D, fully electromagnetic, relativistic particle-in-cell numerical code. For zero guide-field, cases for both open and closed boundary conditions are investigated, where magnetic flux and particles are lost and conserved, respectively. It is found that reconnection rates, out-of-plane currents and density in the X-point increase more rapidly and peak sooner in the closed boundary case, but higher values are reached in the open boundary case. The normalized reconnection rate is fast: 0.10-0.25. In the open boundary case it is shown that an increase of guide-field yields later onsets in the reconnection peak rates, while in the closed boundary case initial peak rates occur sooner but are suppressed. The reconnection current changes similarly with increasing guide-field; however for low guide-fields the reconnection current increases, giving an optimal value for the guide-field between 0.1 and 0.2 times the in-plane field in both cases. Also, in the open boundary case, it is found that for guide-fields of the order of the in-plane magnetic field, the generation of electron vortices occurs. Possible causes of the vortex generation, based on the flow of decoupled particles in the diffusion region and localized plasma heating, are discussed. Before peak reconnection onset, oscillations in the out-of-plane electric field at the X-point are found, ranging in frequency from approximately 1 to 2 ωpe and coinciding with oscillatory reconnection. These oscillations are found to be part of a larger wave pattern in the simulation domain. Mapping the out-of-plane electric field along the central lines of the domain over time and applying a 2D Fourier transform reveal that the waves predominantly correspond to the ordinary and the extraordinary mode and hence may correspond to observable radio waves such as solar radio burst fine structure spikes.
Nanodomain induced anomalous magnetic and electronic transport properties of LaBaCo2O5.5+δ highly epitaxial thin films
Authors: Ruiz-Zepeda F. , Ma C. , Bahena Uribe D. , Cantu-Valle J. , Wang H. , Xu Xing , Yacaman M. J. , Chen C. , Lorenz B. , Jacobson A. J. , Chu P. C. W. , Ponce A.
Published: January 2014

A giant magnetoresistance effect (∼46% at 20 K under 7 T) and anomalous magnetic properties were found in a highly epitaxial double perovskite LaBaCo2O5.5+δ (LBCO) thin film on (001) MgO. Aberration-corrected Electron Microscopy and related analytical techniques were employed to understand the nature of these unusual physical properties. The as-grown film is epitaxial with the c-axis of the LBCO structure lying in the film plane and with an interface relationship given by (100)LBCO || (001)MgO and [001]LBCO || [100]MgO or [010]MgO. Orderly oxygen vacancies were observed by line profile electron energy loss spectroscopy and by atomic resolution imaging. Especially, oxygen vacancy and nanodomain structures were found to have a crucial effect on the electronic transport and magnetic properties.
Spaces of electromagnetic and mechanical constitutive parameters for dissipative media with either positive or negative index
Authors: Dubois J. , Aristégui C. , Poncelet O.
Published: January 2014

Propagation of electromagnetic and acoustic plane waves in dissipative isotropic homogeneous media is described in terms of the Poynting vector and of the complex-valued wave vector. The negative sign of the refractive index, which is explained by the presence of backward bulk waves, is then directly related to the phase angle of the complex-valued wavenumber. Attention is focused on an alternative description dealing with the complex-valued dynamic material parameters: the relative permittivity ϵ and the relative permeability μ for the electromagnetic wave motion, and the bulk modulus κ and the mass density ρ for the acoustic wave motion. The 2D spaces of material parameters (ϵ,μ) and (κ,ρ) are found to be split into regions characterized by their abilities both to induce wave attenuation and to exhibit opposite directions between the energy flow and the direction of the plane wave propagation. Finally, the relevance of such representations is illustrated by superimposing experimentally retrieved and simulated constitutive parameters of media supporting both forward and backward wave motions.
A cascade through spin states in the ultrafast haem relaxation of met-myoglobin
Authors: Consani Cristina , Auböck Gerald , Bräm Olivier , van Mourik Frank , Chergui Majed
Published: January 2014

We report on a study of the early relaxation processes of met-Myoglobin in aqueous solution, using a combination of ultrafast broadband fluorescence detection and transient absorption with a broad UV-visible continuum probe at different pump energies. Reconstruction of the spectra of the transient species unravels the details of the haem photocycle in the absence of photolysis. Besides identifying a branching in the ultrafast relaxation of the haem, we show clear evidence for an electronic character of the intermediates, contrary to the commonly accepted idea that the early time relaxation of the haem is only due to cooling. The decay back to the ground state proceeds partially as a cascade through iron spin states, which seems to be a general characteristic of haem systems.
Hardening mechanisms of high pressure Mg-Li alloys
Authors: Peng Qiuming , Wu Wenshi , Guo Jianxin , Xiang Jianyong , Zhao S. S.
Published: January 2014

High pressure thermal-mechanical treatment (4 GPa) is introduced to improve hardness of a Mg-7 wt. % Li alloy. The improvement in hardness is strongly temperature dependent and the highest hardness occurs in a narrow temperature range around 700 °C. The main reasons for improved hardness are mainly related to the increased phase relative abundance of hcp phase and the formation of superfine {101¯1} compression twins in hcp-Li0.92Mg4.08 phase which effectively inhibits dislocation movement during deformation process. This phase transformation is consistent with the first principles calculations. It demonstrates that high pressure treatment is an effective approach to achieve higher strength Mg-Li based materials
Optical characterization of femtosecond laser induced active channel waveguides in lithium fluoride crystals
Authors: Chiamenti I. , Bonfigli F. , Gomes A. S. L. , Michelotti F. , Montereali R. M. , Kalinowski H. J.
Published: January 2014

We successfully realized broad-band light-emitting color center waveguides buried in LiF crystals by using femtosecond laser pulses. The characterization of the waveguides was performed by optical microscopy, photoluminescence spectra, loss measurements and near-field profiling. The experimental results show that the direct-writing fabrication process induces low-index contrast active channel waveguides: their wavelength-dependent refractive index changes, estimated from 10−3 to 10−4 depending on the writing conditions, allow supporting few modes at visible and near-infrared wavelengths.
Stability, transparency, and conductivity of MgxZn1−xO and CdxZn1−xO: Designing optimum transparency conductive oxides
Authors: Yin Wan-Jian , Dai Lingling , Zhang Lin , Yang Rong , Li Liwei , Guo Ted , Yan Yanfa
Published: January 2014

The stability, transparency, and conductivity of ZnO are suggested to be tailored by alloying with MgO or CdO to meet wide applications. Our Monte Carlo simulation based on first-principle cluster expansion methods partially explain the solubility and stability data scattered in extensive experiments and further reveal that CdxZn1−xO has much higher solubility than prevalent MgxZn1−xO in a large range of experimentally achievable temperature (400 K–1200 K). Furthermore, first-principles calculations based on hybrid functional methods show that CdxZn1−xO has better n-type doping properties than MgxZn1−xO. The optical gap of CdxZn1−xO could be ∼1.5 eV higher than its fundamental gap due to large Moss-Burstein shift. We thus predict that CdxZn1−xO has great potential to be a better transparent conducting oxide than MgxZn1−xO.
Thermoelectric properties of Al-(Mn,X)-Si C54-phase (X = Ru and Re)
Authors: Yamamoto Akio , Miyazaki Hidetoshi , Takeuchi Tsunehiro
Published: January 2014

The lattice thermal conductivity of the Al-Mn-Si C54-phase, which possesses a large magnitude of the Seebeck coefficient and metallic electrical conduction, was greatly reduced by partial substitution of the heavy elements Ru and Re for Mn; these were selected by first principles calculations so as not to produce impurity states near the chemical potential. The heavy element substituted Al-Mn-Si-based C54-phase showed a drastic increase in the dimensionless of figure of merit ZT due to the reduction of the lattice thermal conductivity together with the unchanged electrical properties. The maximum ZT value of the p-type sample and the n-type sample reached 0.12 at 520 K and 0.38 at 540 K, respectively. These values are about five times larger than that of the heavy element-free Al-Mn-Si C54-phase.
Efficient photon extraction from a quantum dot in a broad-band planar cavity antenna
Authors: Ma Yong , Kremer Peter E. , Gerardot Brian D.
Published: January 2014

We analyse the extraction of photons emitted from single InAs quantum dots embedded in planar microcavities. The structures are designed to achieve broad-band operation and high-collection efficiency from a device requiring straightforward fabrication, even with electrical contacts. The designs consist of a quantum dot in a GaAs membrane with asymmetric top and bottom mirrors and a top-side solid immersion lens (SIL). Four separate cases are considered in our design: a GaAs membrane only (case 1), GaAs membrane with a glass SIL on top (case 2), a GaAs membrane with a glass SIL on top and a back mirror consisting of Au (case 3), a GaAs membrane with a glass SIL on top of a distribute Bragg reflector mirror and Au back mirror (case 4). Both finite difference time domain and analytical simulations are used to calculate the electric field, power density, and far-field radiation pattern. For optimized structures (case 4), we obtain significant extraction efficiencies (>50%) with modest Purcell enhancements (∼20%) and a large spectral full-width-half-maximum (>100 nm). The high-extraction efficiency, broad-band operation, and facile fabrication make the proposed structures promising for realistic quantum dot devices.
Resonant and nonresonant funneling through plasmonic gratings in the limit of the aperture width approaching zero
Authors: Bloemer M. J. , Mattiucci N. , D'Aguanno G. , Trimm R. , Akozbek N.
Published: January 2014

We experimentally and theoretically investigate electromagnetic funneling in thick plasmonic gratings as the aperture size approaches zero. Both resonant and nonresonant funneling mechanisms were observed to provide near unity transmission for aperture widths of ∼λ/100. As the apertures become smaller, the resonant funneling process enters into a region of strong absorption followed by complete reflection. In sharp contrast, the broadband, nonresonant funneling mechanism continues to transmit energy at high levels for screens of <1% open area and apertures sizes as small as λ/1500 before finally transitioning to a completely absorbing state without any abatement of the funneling into the apertures.
Motion of 1/3⟨111⟩ dislocations on Σ3 {112} twin boundaries in nanotwinned copper
Authors: Lu N. , Du K. , Lu L. , Ye H. Q.
Published: January 2014

The atomic structure of Σ3 {112} ITBs in nanotwinned Cu is investigated by using aberration-corrected high resolution transmission electron microscopy (HRTEM) and in situ HRTEM observations. The Σ3 {112} ITBs are consisted of periodically repeated three partial dislocations. The in situ HRTEM results show that 1/3[111] partial dislocation moves on the Σ3 {112} incoherent twin boundary (ITB), which was accompanied by a migration of the ITB. A dislocation reaction mechanism is proposed for the motion of 1/3[111] Frank partial dislocation, in which the 1/3[111] partial dislocation exchanges its position with twin boundary dislocations in sequence. In this way, the 1/3[111] dislocation can move on the incoherent twin boundary in metals with low stacking fault energy. Meanwhile, the ITB will migrate in its normal direction accordingly. These results provide insight into the reaction mechanism of 1/3[111] dislocations and ITBs and the associated migration of ITBs.
Shock compression behavior of bi-material powder composites with disparate melting temperatures
Authors: Sullivan Kyle T. , Swift Damian , Barham Matthew , Stölken James , Kuntz Joshua , Kumar Mukul
Published: January 2014

Laser driven experiments were used to investigate the shock compression behavior of powder processed Bismuth/Tungsten (Bi/W) composite samples. The constituents provide different functionality to the composite behavior as Bi could be shock melted at the pressures attained in this work, while the W could not. Samples were prepared by uniaxial pressing, and the relative density was measured as a function of particle size, applied pressure, and composition for both hot and cold pressing conditions. This resulted in sample densities between 73% and 99% of the theoretical maximum density, and also noticeable differences in microstructure in the hot and cold pressed samples. The compression waves were generated with a 1.3 × 1.3 mm square spot directly onto the surface of the sample, using irradiances between 1012 and 1013 W/cm2, which resulted in calculated peak pressures between 50 and 150 GPa within a few micrometers. Sample recovery and post-mortem analysis revealed the formation of a crater on the laser drive surface, and the depth of this crater corresponded to the depth to which the Bi had been melted. The melt depth was found to be primarily a function of residual porosity and composition, and ranged from 167 to 528 μm. In general, a higher porosity led to a larger melt depth. Direct numerical simulations were performed, and indicated that the observed increase in melt depth for low-porosity samples could be largely attributed to increased heating associated with work done for pore collapse. However, the relative scaling was sensitive to composition, with low volume fraction Bi samples exhibiting a much stronger dependence on porosity than high Bi content samples. Select samples were repeated using an Al foil ablator, but there were no noticeable differences ensuring that the observed melting was indeed pressure-driven and was not a result of direct laser heating. The resultant microstructures and damage near the spall surface were also investigated qualitatively.
Adhesive characteristics of low dimensional carbon nanomaterial on actin
Authors: Li Tong , Oloyede Adekunle , Gu YuanTong
Published: January 2014

The biosafety of carbon nanomaterial needs to be critically evaluated with both experimental and theoretical validations before extensive biomedical applications. In this Letter, we present an analysis of the binding ability of two-dimensional monolayer carbon nanomaterial on actin by molecular simulation to understand their adhesive characteristics on F-actin cytoskeleton. The modelling results indicate that the positively charged carbon nanomaterial has higher binding stability on actin. Compared to crystalline graphene, graphene oxide shows higher binding influence on actin when carrying positive surface charge. This theoretical investigation provides insights into the sensitivity of actin-related cellular activities on carbon nanomaterial.
A genetic study on sexual dimorphism of bodyweight in sheep
Authors: Ghafouri-Kesbi Farhad , Mianji Ghodratollah Rahimi , Pirsaraei Zarbakht Ansari , Hafezian Seyed Hasan , Baneh Hasan , Soleimani Bijan
Published: January 2014

The aim of the present study was to investigate the genetic basis of sexual dimorphism of bodyweight in Zandi sheep. To do this, a pedigree including 1450 dams and 170 sires was used. Six bivariate animal models were applied for investigating direct and maternal effects for three age-specific bodyweights (bodyweight at birth, 3 and 6 months of age) in male and female Zandi lambs. The variance components were estimated via REML procedure. Males were, respectively, 6%, 7% and 9% heavier than females at birth, weaning and 6 months of age. Estimates of sexual dimorphism levels (expressed as M/F) were 1.11 at birth, 1.07 at weaning and 1.09 at 6 months of age, which indicated relatively low levels of sexual size dimorphism in the traits studied. Except for birthweight, for which estimates of additive genetic, residual and phenotypic variances as well as direct heritability and additive coefficient of variation were higher in females, for other traits studied, estimates were higher in males. However, regarding direct and maternal effects, none of the differences between the sexes was significant, indicating no need for sexual selection. Cross-sex genetic correlations were 0.862 at birth, 0.918 at weaning and 0.922 at 6 months of age, which highlighted birthweight as the most dimorphic trait. It was concluded that, owing to possible contribution of sexual chromosomes to variation of growth-related traits, bodyweight in male and female lambs may not be under the exactly same genetic control.
Spectra as windows into exoplanet atmospheres
Authors: Burrows Adam S.
Published: January 2014

Understanding a planet’s atmosphere is a necessary condition for understanding not only the planet itself, but also its formation, structure, evolution, and habitability. This requirement puts a premium on obtaining spectra and developing credible interpretative tools with which to retrieve vital planetary information. However, for exoplanets, these twin goals are far from being realized. In this paper, I provide a personal perspective on exoplanet theory and remote sensing via photometry and low-resolution spectroscopy. Although not a review in any sense, this paper highlights the limitations in our knowledge of compositions, thermal profiles, and the effects of stellar irradiation, focusing on, but not restricted to, transiting giant planets. I suggest that the true function of the recent past of exoplanet atmospheric research has been not to constrain planet properties for all time, but to train a new generation of scientists who, by rapid trial and error, are fast establishing a solid future foundation for a robust science of exoplanets.