bluuebunny/crossref_metadata_2025 huggingface dataset:
Facile synthesis of magnetic Bi25FeO40/rGO catalyst with efficient photocatalytic performance for phenolic compounds under visible light
Authors: Wu Yan , Luo Hanjin , Jiang Xiaolu , Wang Hou , Geng Junjie
Published: December 2014

To improve the utilization efficiency of the Bi25FeO40 catalyst, Bi25FeO40-reduced graphene oxide (rGO) composite photo-catalysts were prepared by a facile hydrothermal method.
Polyacrylonitrile/Syzygium aromaticum hierarchical hydrophilic nanocomposite as a carrier for antibacterial drug delivery systems
Authors: Yadav Ramdayal , Balasubramanian K.
Published: December 2014

A versatile, maneuverable electrospinning process was exploited to fabricate intertwined-heterostructure polyacrylonitrile (PAN) nanofibers by incorporating the essential oilSyzygium aromaticumfor antibacterial drug delivery systems.
Green synthesis of zinc oxide nanoparticles using Hibiscus subdariffa leaf extract: effect of temperature on synthesis, anti-bacterial activity and anti-diabetic activity
Authors: Bala Niranjan , Saha S. , Chakraborty M. , Maiti M. , Das S. , Basu R. , Nandy P.
Published: December 2014

Particle size dependent anti-bacterial and anti-diabetic activities of green synthesized ZnO nanoparticles.
[2.2.2]Paracyclophane, preference for η6 or η18 coordination mode including Ag(i) and Sn(ii): a survey into the cation–π interaction nature through relativistic DFT calculations
Authors: Ulloa Carolina Olea , Ponce-Vargas Miguel , de Mattos Piccoli Rafael , Caramori Giovanni F. , Frenking Gernot , Muñoz-Castro Alvaro
Published: December 2014

[2.2.2]Paracyclophane is a versatile π-cryptating structure, which can exhibit η2:η2:η2 and η6:η6:η6 coordination with metal ions, involving two or six carbon atoms in each aromatic ring.
Highly efficient and stable quantum dot-sensitized solar cells based on a Mn-doped CuS counter electrode
Authors: Gopi Chandu V. V. M. , Venkata-Haritha M. , Kim Soo-Kyoung , Rao S. Srinivasa , Punnoose Dinah , Kim Hee-Je
Published: December 2014

A maximum efficiency of 5.46% was achieved with low thickness of 10% Mn–CuS counter electrode.
“Light-assisted evaporation induced self-assembly”: an efficient approach toward ordered carbon materials
Authors: Ghimbeu Camélia Matei , Soprony Mihai , Sima Felix , Vaulot Cyril , Vidal Loïc , Le Meins Jean-Marc , Delmotte Luc
Published: December 2014

The synthesis of ordered porous carbons by a green, simple and rapid approach based on light exposure of a solution of carbon precursors and a soft-template, in the presence or not of a photosensitizer is demonstrated herein along with their formation mechanism.
Hydrocarbon chain growth and hydrogenation on V(100): a density functional theory study
Authors: Wang Hui , Liu Jing-Yao , Chai Zhifang , Wang Dongqi
Published: December 2014

The activation of CO, hydrogenation of CHx (x = 0–4) and C2Hy (y = 0–5) species and carbon chain propagation on V(100) were studied by means of periodic density functional theory (DFT) calculations.
Air-stable ambipolar field-effect transistor based on a solution-processed octanaphthoxy-substituted tris(phthalocyaninato) europium semiconductor with high and balanced carrier mobilities
Authors: Kong Xia , Zhang Xia , Gao Dameng , Qi Dongdong , Chen Yanli , Jiang Jianzhuang
Published: December 2014

Simple solvent vapor annealing over QLS film-based OFET devices fabricated from (Pc)Eu[Pc(ONh)8]Eu[Pc(ONh)8] led to a high and balanced ambipolar performance.
Facile removal of polyvinylpyrrolidone (PVP) adsorbates from Pt alloy nanoparticles
Authors: Luo Muhua , Hong Yuanchen , Yao Weifeng , Huang Cunping , Xu Qunjie , Wu Qiang
Published: December 2014

A facile NaBH4/tert-butylamine (TBA) treatment method for the effective removal of PVP from Pt alloy nanoparticles without affecting the particle morphology.
Low-density, hydrophobic, highly flexible ambient-pressure-dried monolithic bridged silsesquioxane aerogels
Authors: Yun Shan , Luo Hongjie , Gao Yanfeng
Published: December 2014

Ambient-pressure dried monolithic bridged silsesquioxane aerogel with high flexibility and hydrophobicity.
Self-assembled FeS2 cubes anchored on reduced graphene oxide as an anode material for lithium ion batteries
Authors: Wen Xun , Wei Xiaolin , Yang Liwen , Shen Pei Kang
Published: December 2014

A novel composite of reduced graphene oxide (RGO) and FeS2 microparticles self-assembled from small size cubes as a high-performance anode material for lithium-ion batteries (LIBs) has been prepared via a facile one-pot hydrothermal method.
Highly effective anti-corrosion epoxy spray coatings containing self-assembled clay in smectic order
Authors: Li Peng , He Xingliang , Huang Tsao-Cheng , White Kevin L. , Zhang Xi , Liang Hong , Nishimura Riichi , Sue Hung-Jue
Published: December 2014

Epoxy nanocomposite coatings containing self-assembled α-zirconium phosphate nanoplatelets (ZrP) in smectic order were successfully prepared by spray-coating on an aluminum substrate using a simple, energy-efficient fabrication process that is suitable for industrial practices.
Diagnostic imaging and therapeutic application of nanoparticles targeting the liver
Authors: Wang Haolu , Thorling Camilla A. , Liang Xiaowen , Bridle Kim R. , Grice Jeffrey E. , Zhu Yian , Crawford Darrell H. G. , Xu Zhi Ping , Liu Xin , Roberts Michael S.
Published: December 2014

This review summarizes research progress focusing on nanoparticles targeting the liver for both diagnostic and therapeutic purposes at the cellular level.
Antibacterial and osteoinductive capability of orthopedic materials via cation–π interaction mediated positive charge
Authors: Shi Lianxin , Zhang Wei , Yang Kun , Shi Haigang , Li Dan , Liu Jun , Ji Junhui , Chu Paul K.
Published: December 2014

A cation–π interaction mediated bio-interface with promoted positive charge simultaneously enhances the antibacterial and osteoinductive capabilities of orthopedic implants.
Spontaneous formation of core–shell GaAsP nanowires and their enhanced electrical conductivity
Authors: Sun Wen , Huang Yang , Guo Yanan , Liao Zhi Ming , Gao Qiang , Tan Hark Hoe , Jagadish Chennupati , Liao Xiao Zhou , Zou Jin
Published: December 2014

Spontaneous formation of core–shell GaAsP nanowires with P-enriched cores and As-enriched shells, demonstrating enhanced electrical conductivity.
Highly stable and stretchable graphene–polymer processed silver nanowires hybrid electrodes for flexible displays
Authors: Zhang Qi , Di Yanfei , Huard Chad M. , Guo L. Jay , Wei Jie , Guo Jinbao
Published: December 2014

Highly stable and flexible graphene–polymer processed silver nanowires hybrid transparent electrodes and their application for flexible liquid crystal display were demonstrated.
CO2-switchable poly (N-isopropylacrylamide) microgel-based etalons
Authors: Zhang Qiang Matthew , Ahiabu Andrews , Gao Yongfeng , Serpe Michael J.
Published: December 2014

A photonic device containing pyridine-modified microgels was fabricated, which exhibits reversibly tunable optical properties upon exposure to CO2.
A unique white electroluminescent one-dimensional europium(iii) coordination polymer
Authors: Xu Hui , Wang Jianzhe , Wei Ying , Xie Guohua , Xue Qin , Deng Zhaopeng , Huang Wei
Published: December 2014

A one-dimensional Eu3+ coordination polymer on the basis of phosphine oxide ligand achieved efficient single-polymer white electroluminescence.
The Video Head Impulse Test in a Case of Suspected Bilateral Loss of Vestibular Function
Authors: Albernaz Pedro , Cusin Flavia
Published: December 2014

Introduction A patient who had no symptoms suggestive of bilateral loss of vestibular function presented no responses in rotational and caloric tests.

Objectives To demonstrate the importance of the video head impulse test in neuro-otologic diagnosis.

Resumed Report This patient had a neuro-otologic evaluation and presented no responses in torsion swing tests, caloric tests, and rotational tests in a Bárány chair. The video head impulse test elicited responses in four of the six semicircular canals.

Conclusion Absent responses in caloric and rotatory tests alone are not sufficient to diagnose bilateral loss of vestibular function.
Smoothed particle hydrodynamics model for Landau-Lifshitz-Navier-Stokes and advection-diffusion equations
Authors: Kordilla Jannes , Pan Wenxiao , Tartakovsky Alexandre
Published: December 2014

We propose a novel smoothed particle hydrodynamics (SPH) discretization of the fully coupled Landau-Lifshitz-Navier-Stokes (LLNS) and stochastic advection-diffusion equations. The accuracy of the SPH solution of the LLNS equations is demonstrated by comparing the scaling of velocity variance and the self-diffusion coefficient with kinetic temperature and particle mass obtained from the SPH simulations and analytical solutions. The spatial covariance of pressure and velocity fluctuations is found to be in a good agreement with theoretical models. To validate the accuracy of the SPH method for coupled LLNS and advection-diffusion equations, we simulate the interface between two miscible fluids. We study formation of the so-called “giant fluctuations” of the front between light and heavy fluids with and without gravity, where the light fluid lies on the top of the heavy fluid. We find that the power spectra of the simulated concentration field are in good agreement with the experiments and analytical solutions. In the absence of gravity, the power spectra decay as the power −4 of the wavenumber—except for small wavenumbers that diverge from this power law behavior due to the effect of finite domain size. Gravity suppresses the fluctuations, resulting in much weaker dependence of the power spectra on the wavenumber. Finally, the model is used to study the effect of thermal fluctuation on the Rayleigh-Taylor instability, an unstable dynamics of the front between a heavy fluid overlaying a light fluid. The front dynamics is shown to agree well with the analytical solutions.
Momentum transfer within a porous medium. I. Theoretical derivation of the momentum balance on the solid skeleton
Authors: Minale Mario
Published: December 2014

The momentum balance on the solid skeleton of a porous medium like porous rocks, foam metals, or porous brushes is, here, theoretically derived with the volume averaging method. It is derived for both homogeneous and non-homogeneous porous media and for the latters no length scales constraints are invoked. The momentum balance on the solid skeleton holds in the whole porous medium and contains volume averaged stresses and velocity. For heterogeneous porous media, it is coupled with the fluid momentum balance through a general averaged quantity, while in the homogeneous case, it is coupled with Darcy’s equation, corrected with the first and the second Brinkman’s term, through a geometrically rescaled Darcy’s term. This latter equation coincides with Biot’s equation for poro-elasticity, but it is here derived with a different formalism. This approach gives the opportunity to derive a new stress boundary condition at the interface between a porous medium and a homogeneous fluid.
Momentum transfer within a porous medium. II. Stress boundary condition
Authors: Minale Mario
Published: December 2014

In this paper, we derive a boundary condition at the interface between a free fluid and a porous medium stating that the stress is transferred both to the fluid within the porous medium and to the solid skeleton. A zero stress jump is obtained so that the total stress is preserved at the interface. The boundary condition is obtained with the volume averaging method following the approach of Ochoa-Tapia and Whitaker [“Momentum transfer at the boundary between a porous medium and a homogeneous fluid—I. Theoretical development,” Int. J. Heat Mass Transfer 38(14), 2635–2646 (1995)], but starting from the momentum balances written on the fluid and on the solid of the porous region, the latter was derived in part I of this paper. In the same way, also the boundary condition at the interface between a porous medium and a homogeneous solid is obtained. Both boundary conditions describe the equilibrium of forces at the interface, where part of the stress is carried by the solid skeleton and part by the fluid within the porous medium. With the derived boundary conditions, together with the stress transfer equation within the solid skeleton, it is now possible to satisfy the overall force equilibrium on a shear cell partially filled with a porous medium.
First order approximation for quadratic dispersive equations by the renormalization group approach
Authors: Wang Lin
Published: December 2014

In this paper, we study the application of the renormalization group method to a system of partial differential equations. Together with constructing a long-time first order approximation of the solution of the system, we compare the difference between the true solution and the approximate formation with the help of dispersive estimates in Lp space.
When the charge on a planar conductor is a function of its curvature
Authors: Cross Daniel J.
Published: December 2014

While there is no general relationship between the electric charge density on a conducting surface and its curvature, the two quantities can be functionally related in special circumstances. This paper presents a complete classification of two-dimensional conductors for which charge density is a function of boundary curvature. Whenever the curvature function is non-injective, the conductor must transform under one of the planar symmetry groups. In particular, for the charge density on a closed conductor with smooth boundary to be a function of its curvature, the conductor must possess dihedral symmetry with a mirror line running through each curvature extremum. Several examples are presented along with explicit charge-curvature functions. Both increasing and decreasing functions were found.
Unveiling the mechanism of photoinduced isomerization of the photoactive yellow protein (PYP) chromophore
Authors: Gromov Evgeniy V.
Published: December 2014

A detailed theoretical analysis, based on extensive ab initio second-order approximate coupled cluster calculations, has been performed for the S1 potential energy surface (PES) of four photoactive yellow protein (PYP) chromophore derivatives that are hydrogen bonded with two water molecules and differ merely in the carbonyl substituent. The main focus is put on contrasting the isomerization properties of these four species in the S1 excited state, related to torsion around the chromophore's single and double carbon-carbon bonds. The analysis provides evidence of the different isomerization behavior of these four chromophore complexes, which relates to the difference in their carbonyl substituents. While a stable double-bond torsion pathway exists on the S1 PES of the chromophores bearing the –O–CH3 and –NH2 substituents, this is not the case for the –S–CH3 and –CH3 substituted species. The presence of the –S–CH3 group leads to a strong instability of the chromophore with respect to the single-bond twist, whereas in the case of the –CH3 substituent a crossing of the S1 and S2 PESs occurs, which perturbs the pathway. Based on this analysis, the key factors that support the double-bond torsion have been identified. These are (i) the hydrogen bonds at the phenolic oxygen of the chromophore, (ii) the weak electron-acceptor character of the carbonyl group, and (iii) the ethylene-like pattern of the torsion in the beginning of the process. Our results suggest that the interplay between these factors determines the chromophore's isomerization in the solvent environment and in the native PYP environment.
Gaussian distributions, Jacobi group, and Siegel-Jacobi space
Authors: Molitor Mathieu
Published: December 2014

Let N be the space of Gaussian distribution functions over ℝ, regarded as a 2-dimensional statistical manifold parameterized by the mean μ and the deviation σ. In this paper, we show that the tangent bundle of N, endowed with its natural Kähler structure, is the Siegel-Jacobi space appearing in the context of Number Theory and Jacobi forms. Geometrical aspects of the Siegel-Jacobi space are discussed in detail (completeness, curvature, group of holomorphic isometries, space of Kähler functions, and relationship to the Jacobi group), and are related to the quantum formalism in its geometrical form, i.e., based on the Kähler structure of the complex projective space. This paper is a continuation of our previous work [M. Molitor, “Remarks on the statistical origin of the geometrical formulation of quantum mechanics,” Int. J. Geom. Methods Mod. Phys. 9(3), 1220001, 9 (2012); M. Molitor, “Information geometry and the hydrodynamical formulation of quantum mechanics,” e-print arXiv (2012); M. Molitor, “Exponential families, Kähler geometry and quantum mechanics,” J. Geom. Phys. 70, 54–80 (2013)], where we studied the quantum formalism from a geometric and information-theoretical point of view.
Curvature-induced bound states in Robin waveguides and their asymptotical properties
Authors: Exner Pavel , Minakov Alexander
Published: December 2014

We analyze bound states of Robin Laplacian in infinite planar domains with a smooth boundary, in particular, their relations to the geometry of the latter. The domains considered have locally straight boundary being, for instance, locally deformed halfplanes or wedges, or infinite strips, alternatively they are the exterior of a bounded obstacle. In the situation when the Robin condition is strongly attractive, we derive a two-term asymptotic formula in which the next-to-leading term is determined by the extremum of the boundary curvature. We also discuss the non-asymptotic case of attractive boundary interaction and show that the discrete spectrum is nonempty if the domain is a local deformation of a halfplane or a wedge of angle less than π, and it is void if the domain is concave.
Multilevel characteristics and memory mechanisms for nonvolatile memory devices based on CuInS2 quantum dot-polymethylmethacrylate nanocomposites
Authors: Zhou Yang , Yun Dong Yeol , Kim Sang Wook , Kim Tae Whan
Published: December 2014

Nonvolatile memory devices based on CuInS2 (CIS) quantum dots (QDs) embedded in a polymethylmethacrylate (PMMA) layer were fabricated using spin-coating method. The memory window widths of the capacitance-voltage (C-V) curves for the Al/CIS QDs embedded in PMMA layer/p-Si devices were 0.3, 0.6, and 1.0 V for sweep voltages of ±3, ±5, and ±7 V, respectively. Capacitance-cycle data demonstrated that the charge-trapping capability of the devices with an ON/OFF ratio value of 2.81 × 10−10 was maintained for 8 × 103 cycles without significant degradation and that the extrapolation of the ON/OFF ratio value to 1 × 106 cycles converged to 2.40 × 10−10, indicative of the good stability of the devices. The memory mechanisms for the devices are described on the basis of the C-V curves and the energy-band diagrams.
Atomic force microscopy deep trench and sidewall imaging with an optical fiber probe
Authors: Xie Hui , Hussain Danish , Yang Feng , Sun Lining
Published: December 2014

We report a method to measure critical dimensions of micro- and nanostructures using the atomic force microscope (AFM) with an optical fiber probe (OFP). This method is capable of scanning narrow and deep trenches due to the long and thin OFP tip, as well as imaging of steep sidewalls with unique profiling possibilities by laterally tilting the OFP without any modifications of the optical lever. A switch control scheme is developed to measure the sidewall angle by flexibly transferring feedback control between the Z- and Y-axis, for a serial scan of the horizontal surface (raster scan on XY-plane) and sidewall (raster scan on the YZ-plane), respectively. In experiments, a deep trench with tapered walls (243.5 μm deep) and a microhole (about 14.9 μm deep) have been imaged with the orthogonally aligned OFP, as well as a silicon sidewall (fabricated by deep reactive ion etching) has been characterized with the tilted OFP. Moreover, the sidewall angle of TGZ3 (AFM calibration grating) was accurately measured using the switchable scan method.
Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air
Authors: Zhu Jiajian , Gao Jinlong , Li Zhongshan , Ehn Andreas , Aldén Marcus , Larsson Anders , Kusano Yukihiro
Published: December 2014

Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light to the governing mechanism of the sustained spark-suppressed AC gliding arc discharge.
Chaotic behavior of light-assisted physical aging in arsenoselenide glasses
Authors: Shpotyuk O. , Balitska V. , Kozdras A. , Hacinliyan A. S. , Skarlatos Y. , Kusbeyzi Aybar I. , Aybar O. O.
Published: December 2014

The theory of strange attractors is shown to be adequately applicable for analyzing the kinetics of light-assisted physical aging revealed in structural relaxation of Se-rich As-Se glasses below glass transition. Kinetics of enthalpy losses is used to determine the phase space reconstruction parameters. Observed chaotic behaviour (involving chaos and fractal consideration such as detrended fluctuation analysis, attractor identification using phase space representation, delay coordinates, mutual information, false nearest neighbours, etc.) reconstructed via the TISEAN program package is treated within a microstructure model describing multistage aging behaviour in arsenoselenide glasses. This simulation testifies that photoexposure acts as an initiating factor only at the beginning stage of physical aging, thus facilitating further atomic shrinkage of a glassy backbone.
Electronic and thermal effects in the insulator-metal phase transition in VO2 nano-gap junctions
Authors: Joushaghani Arash , Jeong Junho , Paradis Suzanne , Alain David , Stewart Aitchison J. , Poon Joyce K. S.
Published: December 2014

By controlling the thermal transport of VO2 nano-gap junctions using device geometry, contact material, and applied voltage waveforms, the electronically induced insulator-metal phase transition is investigated in the adiabatic heating and transient carrier injection regimes. With a gradual ramping of an applied voltage on a microsecond time scale, the transition electric field threshold can be directly reduced by the Joule heating. With an abrupt applied voltage, the transition threshold is initiated by carriers injected within the first tens of nanoseconds, but the complete insulator-metal phase transition is limited by thermal redistribution times to hundreds of nanoseconds.
Relation between the electroforming voltage in alkali halide-polymer diodes and the bandgap of the alkali halide
Authors: Bory Benjamin F. , Wang Jingxin , Gomes Henrique L. , Janssen René A. J. , De Leeuw Dago M. , Meskers Stefan C. J.
Published: December 2014

Electroforming of indium-tin-oxide/alkali halide/poly(spirofluorene)/Ba/Al diodes has been investigated by bias dependent reflectivity measurements. The threshold voltages for electrocoloration and electroforming are independent of layer thickness and correlate with the bandgap of the alkali halide. We argue that the origin is voltage induced defect formation. Frenkel defect pairs are formed by electron–hole recombination in the alkali halide. This self-accelerating process mitigates injection barriers. The dynamic junction formation is compared to that of a light emitting electrochemical cell. A critical defect density for electroforming is 1025/m3. The electroformed alkali halide layer can be considered as a highly doped semiconductor with metallic transport characteristics.
Operation of the GaSb p-channel metal-oxide-semiconductor field-effect transistors fabricated on (111)A surfaces
Authors: Nishi K. , Yokoyama M. , Yokoyama H. , Hoshi T. , Sugiyama H. , Takenaka M. , Takagi S.
Published: December 2014

We demonstrate the operation of GaSb p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs) on (111)A surfaces with Al2O3 gate dielectrics formed by atomic-layer deposition at 150 °C. The p-MOSFETs on (111)A surfaces exhibit higher drain current and lower subthreshold swing than those on (100) surfaces. We find that the interface-state density (Dit) values at the Al2O3/GaSb MOS interfaces on the (111)A surfaces are lower than those on the (100) surfaces, which can lead to performance enhancement of the GaSb p-MOSFETs on (111)A surfaces. The mobility of the GaSb p-MOSFETs on (111)A surfaces is 80% higher than that on (100) surfaces.
Diocotron modulation in an electron plasma through continuous radio-frequency excitation
Authors: Paroli B. , Maero G. , Pozzoli R. , Romé M.
Published: December 2014

The application of a radio-frequency (RF) excitation to any electrode of a Penning-Malmberg trap may result in significant electron heating and ionization of the residual gas with the formation of a plasma column when the RF frequency is of the order or larger than the typical axial bounce frequencies of few-eV electrons. The use of a quadrupolar excitation can induce additional phenomena, like formation of dense, narrow-cross section columns which exhibit an mθ=1 diocotron mode, i.e., a rotation of their center around the trap axis. A series of experiments is presented and discussed showing that the continuous application of such excitation causes a dramatic perturbation of the plasma equilibrium also involving continuous production and loss of particles in the trapping region. In particular, the growth of the first diocotron mode is suppressed even in the presence of ion resonance and resistive instability and the mode exhibits steady-state or underdamped amplitude and frequency modulations, typically in the Hertz range.
Intrinsic carrier multiplication efficiency in bulk Si crystals evaluated by optical-pump/terahertz-probe spectroscopy
Authors: Yamashita G. , Matsubara E. , Nagai M. , Kanemitsu Y. , Ashida M.
Published: December 2014

We estimated the carrier multiplication efficiency in the most common solar-cell material, Si, by using optical-pump/terahertz-probe spectroscopy. Through close analysis of time-resolved data, we extracted the exact number of photoexcited carriers from the sheet carrier density 10 ps after photoexcitation, excluding the influences of spatial diffusion and surface recombination in the time domain. For incident photon energies greater than 4.0 eV, we observed enhanced internal quantum efficiency due to carrier multiplication. The evaluated value of internal quantum efficiency agrees well with the results of photocurrent measurements. This optical method allows us to estimate the carrier multiplication and surface recombination of carriers quantitatively, which are crucial for the design of the solar cells.
Experimental realization of magnetic energy concentration and transmission at a distance by metamaterials
Authors: Prat-Camps Jordi , Navau Carles , Sanchez Alvaro
Published: December 2014

Concentrating magnetic energy in a desired volume is an important requirement for many technologies. Here, we experimentally realize a superconductor-ferromagnetic metamaterial that allows to concentrate the magnetostatic energy in its interior and in other situations to amplify the energy in its exterior. We show that surrounding two distant current loops with two such metamaterials enhance the magnetostatic coupling between them. We also demonstrate that a ferromagnetic-only metamaterial, without superconducting parts, achieves these properties with only a slight decrease in performance. Results may be applied to increase the sensitivity of magnetic sensors or for enhancing wireless power transmission, where efficiency depends critically on the magnetic coupling strength between source and receiver.
Pushing the limits of acoustics at the nanoscale using femtosecond transient interferometry
Authors: Devos A. , Sadtler S. , Mante P.-A. , Le Louarn A. , Emery P.
Published: December 2014

Picosecond acoustics is the perfect technique for measuring elastic properties at nanoscale. But there still are some limitations to reach in-plane properties of ultra-thin films related to optical detection of ultra-high frequency surface acoustic waves. Here, we demonstrate that it is possible to push the limits of the technique using an interferometric detection instead of a usual reflectometry scheme. The experimental observations are supported by a simple model which explains from where comes the previous limitations and why it is possible to overcome it using the interferometric setup. Thanks to those results, it is possible to excite and detect very high frequency surface acoustic waves confined in ultra-thin layer using conventional femtosecond laser and optical setup.
Nanometer-thick flat lens with adjustable focus
Authors: Son T. V. , Ba C. O. F. , Vallée R. , Haché A.
Published: December 2014

We report laser beam focusing by a flat, homogeneous film with a thickness of less than 100 nm. The effect relies on refractive index changes occurring in vanadium dioxide as it undergoes a phase transition from insulator to metal. Phase front curvature is achieved by means of temperature gradients, and adjustable focal lengths from infinity to 30 cm are attained.
Quantum spin Hall states in graphene interacting with WS2 or WSe2
Authors: Kaloni T. P. , Kou L. , Frauenheim T. , Schwingenschlögl U.
Published: December 2014

In the framework of first-principles calculations, we investigate the structural and electronic properties of graphene in contact with as well as sandwiched between WS2 and WSe2 monolayers. We report the modification of the band characteristics due to the interaction at the interface and demonstrate that the presence of the dichalcogenide results in quantum spin Hall states in the absence of a magnetic field.
Externally driven global Alfvén eigenmodes applied for effective mass number measurement on TCABR
Authors: Puglia P. G. P. P. , Elfimov A. G. , Ruchko L. F. , Galvão R. M. O. , Guimarães-Filho Z. , Ronchi G. ,   TCABR Team
Published: December 2014

The excitation and detection of Global Alfvén Eigenmodes on TCABR for diagnostic purposes are presented. The modes can be excited with one or two in-vessel antennae, with up to 15 A of current in each, in the frequency range from 2 to 4 MHz. This scheme allows the estimation of the effective mass number at the plasma center, which value is affected by impurity concentration in the core. An amplifier based on MOSFETs is used to excite the waves driven by low power, in order to not change the basic plasma parameters. The variation of the GAE with density is verified and the location of the mode resonance at the plasma center is confirmed by the sawtooth beating, so that the correspondingly beating phase inversion improves the precision on the resonant condition determination. The toroidal parity of the modes N = 1,2 is determined by use of two opposite located antennae with different phase of the RF current. Knowledge of toroidal mode number is important as it identifies GAE location and defines the estimated effective mass value. The estimated value for Aeff is ∼1.4–1.5, corresponding to 5–7% of carbon impurity concentration. The measured value of Aeff is used to estimate Zeff, which is compared to older TCA experiments and the value obtained by the Spitzer conductivity.
Graphene as a protective coating and superior lubricant for electrical contacts
Authors: Berman Diana , Erdemir Ali , Sumant Anirudha V.
Published: December 2014

Potential for graphene to be used as a lubricant for sliding electrical contacts has been evaluated. Graphene, being deposited as a sporadic flakes on the gold substrate sliding against titanium nitride ball shows not only significant improvement in tribological behavior by reducing both friction (by factor of 2–3) and wear (by 2 orders) but also, even more importantly, demonstrates stable and low electrical resistance at the sliding contacts undergoing thousands of sliding passes regardless of the test environment (i.e., both in humid and dry conditions).
Tunable mid-infrared plasmonic band-pass filter based on a single graphene sheet with cavities
Authors: Li Hong-Ju , Wang Ling-Ling , Sun Bin , Huang Zhen-Rong , Zhai Xiang
Published: December 2014

The single graphene sheet with two cavities constructed on substrates is proposed and numerically investigated by using the finite-difference time-domain (FDTD) method. Thanks to the two introduced cavities, the sandwiched graphene strip behaves as a line-shaped plasmonic resonator. The simple single graphene sheet hence exhibits an outstanding band-pass filtering effect. The transmission spectrum is tuned dynamically not only via changing the length of the graphene strip sandwiched in cavities but also by a small change in the chemical potential of graphene. Simulation results are confirmed by the standing wave equation. In addition, the wavelength of the transmission peak can be tuned linearly by changing the substrate and the proposed structure hence has potential applications in mid-infrared plasmonic sensors. The transmission spectrum is also optimized by changing the width of the cavity. Our studies may be important for the fabrication of nano-integrated circuits for optical communication in the mid-infrared region.
Pyroelectric and dielectric properties of ferroelectric films with interposed dielectric buffer layers
Authors: Espinal Y. , Kesim M. T. , Misirlioglu I. B. , Trolier-McKinstry S. , Mantese J. V. , Alpay S. P.
Published: December 2014

The dielectric and pyroelectric properties of c-domain ferroelectric films with linear dielectric buffer layers were investigated theoretically. Computations were carried out for multilayers consisting of PbZr0.2Ti0.8O3 with Al2O3, SiO2, Si3N4, HfO2, and TiO2 buffers on metalized Si. It is shown that the dielectric and pyroelectric properties of such multilayers can be increased by the presence of the buffer compared to ferroelectric monolayers. Calculations for PbZr0.2Ti0.8O3 films with 1% Al2O3 interposed between electrodes on Si show that the dielectric and pyroelectric coefficients are 310 and 0.070 μC cm−2  °C−1, respectively. Both values are higher than the intrinsic response of PbZr0.2Ti0.8O3 monolayer on Si.
Polarization of Bi2Te3 thin film in a floating-gate capacitor structure
Authors: Yuan Hui , Zhang Kai , Li Haitao , Zhu Hao , Bonevich John E. , Baumgart Helmut , Richter Curt A. , Li Qiliang
Published: December 2014

Metal-Oxide-Semiconductor (MOS) capacitors with Bi2Te3 thin film sandwiched and embedded inside the oxide layer have been fabricated and studied. The capacitors exhibit ferroelectric-like hysteresis which is a result of the robust, reversible polarization of the Bi2Te3 thin film while the gate voltage sweeps. The temperature-dependent capacitance measurement indicates that the activation energy is about 0.33 eV for separating the electron and hole pairs in the bulk of Bi2Te3, and driving them to either the top or bottom surface of the thin film. Because of the fast polarization speed, potentially excellent endurance, and the complementary metal–oxide–semiconductor compatibility, the Bi2Te3 embedded MOS structures are very interesting for memory application.
Determination of alloy composition and strain in multiple AlGaN buffer layers in GaN/Si system
Authors: Kadir Abdul , Huang Chieh Chih , Kian Lee Kenneth Eng , Fitzgerald Eugene A. , Chua Soo Jin
Published: December 2014

A method for absolute evaluation of alloy composition and strain in AlGaN buffer layers in GaN/Si system is described, which can be applied to any III-nitride alloys hetero-epitaxially grown on Si (111) or sapphire (0001) substrate. Absolute measurements of reciprocal space maps of (10-14) nitride layers are performed with the help of Si (313) reciprocal lattice points. The alloy composition and strain-relaxation state in all layers are directly calculated from the absolute values of reciprocal lattice points referenced to the Si substrate. The proposed method of analysis using Si substrate is more accurate than currently favored method in which an epitaxial GaN layer is used as the reference. The knowledge of strain state and alloy composition with greater accuracy would be useful in designing and growing III-nitride devices.
Gold nanosphere enhanced green and red fluorescence in ZnO: Al, Eu3+
Authors: Bishnoi Swati , Das Rupali , Chawla Santa
Published: December 2014

Gold nanoparticles can generate near field due to surface plasmon resonance (SPR) in the visible region. Such near field has the ability to enhance fluorescence of optimally proximal emitters. We have observed augmented green (intrinsic) and red (Eu3+) emission under UV excitation (375 nm) from an important semiconductor ZnO:Al, Eu3+ when optimally conjugated with gold nanospheres. Local field generated by gold nanosphere (∼30 nm) is simulated through finite difference time domain method, and a direct correlation with fluorescence enhancement is established.
Energetics and magnetism of Co-doped GaN(0001) surfaces: A first-principles study
Authors: Qin Zhenzhen , Xiong Zhihua , Qin Guangzhao , Chen Lanli
Published: December 2014

A comprehensive first-principles study of the energetics, electronic, and magnetic properties of Co-doped GaN(0001) thin films are presented and the effect of surface structure on the magnetic coupling between Co atoms is demonstrated. It is found that Co atoms prefer to substitute the surface Ga sites in different growth conditions. In particular, a CoN/GaN interface structure with Co atoms replacing the first Ga layer is preferred under N-rich and moderately Ga-rich conditions, while CoGax/GaN interface is found to be energetically stable under extremely Ga-rich conditions. It is worth noted that the antiferromagnetic coupling between Co atoms is favorable in clean GaN(0001) surface, but the existence of ferromagnetism would be expected to occur as Co concentration increased in Ga-bilayer GaN(0001) surface. Our study provides the theoretical understanding for experimental research on Co-doped GaN films and might promise the Co:GaN system potential applications in spin injection devices.
Metal-insulator-transition in SrTiO3 induced by argon bombardment combined with field effect
Authors: Xu Jie , Zhu Zhengyong , Zhao Hengliang , Luo Zhijiong
Published: December 2014

By fabricating the Field-Effect-Transistors on argon bombardment SrTiO3 substrates, not only we have achieved one of the best mobility for Field-Effect-Transistors fabricated on SrTiO3, but also realized strong field induced Metal-Insulator-Transition. The critical sheet resistance for the Metal-Insulator-Transition is only 1/7 of the value obtained in the former experiments, indicating a different mechanism. Further study shows that the Metal-Insulator-Transition can be attributed to the oxygen vacancies formed after the bombardment becoming the electron donor under the electric field modulation, increasing SrTiO3 surface electron density and transforming the substrate into metallic state.
Securing Tar Sands Circulation: Risk, Affect, and Anticipating the Line 9 Reversal
Authors: Grant Sonia
Published: December 2014

“It's not a question of whether a spill happens—only when”, rings an oft-repeated slogan of oil pipeline opponents in Eastern Canada. Meanwhile, pipeline proponents are adamant that Canada must either “pipe or perish”. Through a case study of a controversial tar sands pipeline project (the Line 9 reversal), this paper examines the workings of risk in environmental politics. I explore the similar anticipatory logics that undergird both support for and opposition to the Line 9 reversal, and query the blurry lines between environmental precaution and security preemption. I ask what a preoccupation with emergent risks enables, and what possibilities it might foreclose. As securing the future necessarily raises the question, ‘for whom?’, I suggest that one troubling consequence of a preoccupation with security is the potential to overlook which lives and ways of being in the world might be neglected in the rush to secure others. The analysis draws on ethnographic interviews and observations to explore the (necro)biopolitical dimensions of pipeline debates, and asks how we might anticipate otherwise.
Mechanisms for the effective implementation of an allied health assistant trainee: a qualitative study of a speech language pathology assistant
Authors: Nancarrow Susan A. , Moran Anna , Sullivan Rebecca
Published: December 2014

Objective
This paper explores the impact and mechanisms for successful implementation of a speech language pathology assistant (SLPA) role into a rehabilitation setting using a traineeship approach.

Methods
Multiple data sources were used, including interviews with key stakeholders, documentary evidence and a workload audit.

Results
The SLPA role increased clinical service capacity by 28 h per week across the service and required a total of 3 h per week of supervision input (the equivalent of 38 min per speech and language pathologist (SLP)). The SLPA used non-clinical time for training and administration. Mechanisms that facilitated the implementation of the SLPA role were: support for existing staff; formal knowledge and skills in training; consultation and engagement; access to a competency framework; close working with the registered training organisation; clearly defined role and delegation boundaries; clear supervision structures; confidence in own role; supportive organisational culture; vision for expansion of the role; engaging the SLPs in training and development; and a targeted recruitment approach.

Conclusion
The development and implementation of a new trainee SLPA role using a traineeship approach required a large amount of supervision and training input from the SLPs. However, it was perceived that these efforts were offset by the increased service capacity provided by the introduction of a trainee role and the high levels of satisfaction with the new role.

What is known about this topic?
Efficient delegation to assistants requires supervising staff to have a clear understanding of the roles and experience of assistants. There has been little evaluation of assistant training models to date.

What does this paper add?
The net benefit of an allied health assistant in speech pathology far outweighs the input required to provide training and supervision. The paper identifies a range of mechanisms to facilitate the implementation and efficient use of the assistant role.

What are the implications for practitioners?
The implementation of assistant roles requires support for both the assistant and the supervising staff member. Engaging the supervising staff in training the assistant enhances role understanding and effective delegation to the assistant staff member. Although the role development requires a great deal of local investment, there is potential for more efficient implementation of new roles through sharing of resources, such as competencies, assessments and training tools.
Molecular-dynamics simulations of urea nucleation from aqueous solution
Authors: Salvalaglio Matteo , Perego Claudio , Giberti Federico , Mazzotti Marco , Parrinello Michele
Published: December 2014

Significance

Nucleation from solution is a ubiquitous process that plays important roles in physics, chemistry, engineering, and material science. Despite its importance, nucleation is far from being completely understood. In this work, we combine advanced molecular-dynamics simulation techniques and theory to provide a description of urea nucleation from aqueous solution. In particular, our analysis shows that a two-step nucleation mechanism is favorable and that two polymorphs are seen to compete in the early stages of the nucleation process. In our analysis, we have derived and validated a theoretical correction to finite-size effects to compute free-energy profiles in the limit of a macroscopic system at constant supersaturation.
NGC 7789: AN OPEN CLUSTER CASE STUDY
Authors: Overbeek Jamie C. , Friel Eileen D. , Jacobson Heather R. , Johnson Christian I. , Pilachowski Catherine A. , Mészáros Szabolcs
Published: December 2014

We have obtained high-resolution spectra of 32 giants in the open cluster NGC 7789 using the Wisconsin–Indiana–Yale–NOAO Hydra spectrograph. We explore differences in atmospheric parameters and elemental abundances caused by the use of the linelist developed for the Gaia-ESO Survey (GES) compared to one based on Arcturus used in our previous work. [Fe/H] values decrease when using the GES linelist instead of the Arcturus-based linelist; these differences are probably driven by systematically lower (∼−0.1 dex) GES surface gravities. Using the GES linelist we determine abundances for 10 elements—Fe, Mg, Si, Ca, Ti, Na, Ni, Zr, Ba, and La. We find the clusterʼs average metallicity [Fe/H] = 0.03 ± 0.07 dex, in good agreement with literature values, and a lower [Mg/Fe] abundance than has been reported before for this cluster (0.11 ± 0.05 dex). We also find the neutron-capture element barium to be highly enhanced—[Ba/Fe] = +0.48 ± 0.08—and disparate from cluster measurements of neutron-capture elements La and Zr (−0.08 ± 0.05 and 0.08 ± 0.08, respectively). This is in accordance with recent discoveries of supersolar Ba enhancement in young clusters along with more modest enhancement of other neutron-capture elements formed in similar environments.
TRANSITING PLANETS WITH LSST. I. POTENTIAL FOR LSST EXOPLANET DETECTION
Authors: Lund Michael B. , Pepper Joshua , Stassun Keivan G.
Published: December 2014

The Large Synoptic Survey Telescope (LSST) is designed to meet several scientific objectives over a 10 year synoptic sky survey. Beyond its primary goals, the large amount of LSST data can be exploited for additional scientific purposes. We show that LSST data are sufficient to detect the transits of exoplanets, including planets orbiting stars that are members of stellar populations that have so far been largely unexplored. Using simulated LSST light curves, we find that existing transit detection algorithms can identify the signatures of Hot Jupiters around solar-type stars, Hot Neptunes around K-dwarfs, and (in favorable cases) Super-Earths in habitable-zone orbits of M-dwarfs. We also find that LSST may identify Hot Jupiters orbiting stars in the Large Magellanic Cloud—a remarkable possibility that would advance exoplanet science into the extragalactic regime.
Noncommutative Boyd interpolation theorems
Authors: Dirksen Sjoerd
Published: December 2014

We present a new, elementary proof of Boyd’s interpolation theorem. Our approach naturally yields a noncommutative version of this result and even allows for the interpolation of certain operators on

ℓ
1

\ell ^1

-valued noncommutative symmetric spaces. By duality we may interpolate several well-known noncommutative maximal inequalities. In particular we obtain a version of Doob’s maximal inequality and the dual Doob inequality for noncommutative symmetric spaces. We apply our results to prove the Burkholder-Davis-Gundy and Burkholder-Rosenthal inequalities for noncommutative martingales in these spaces.