bluuebunny/crossref_metadata_2025 huggingface dataset:
Economic dispatch of wind integrated power systems with energy storage considering composite operating costs
Authors: Chen Houhe , Zhang Rufeng , Li Guoqing , Bai Linquan , Li Fangxing
Published: March 2016

An economic dispatch (ED) model is proposed in this study for accommodating high penetrations of wind power with the integration of battery energy storage (BES) in power systems. In the proposed ED model, a wind‐storage combined system (WSCS) model is studied to collectively mitigate the output fluctuations and improve the wind power utilisation. In addition, the proposed concept of composite operating costs include the unit operation cost, environmental cost, reserve cost, compensation cost for wind power curtailment, and energy loss cost of ES. With the minimisation of the composite operating costs as the objective function of the proposed ED model with WSCS, a modified bacterial foraging algorithm (MBFA) is proposed to solve the optimisation problem based on a combination of the bacterial foraging algorithm (BFA) and the Particle Swarm Optimisation (PSO). Furthermore, the case study on the IEEE 30‐bus system has been used to demonstrate the feasibility and effectiveness of the proposed ED model and the performance improvement of the MBFA algorithm over BFA or PSO alone. The comparison between different scenarios shows that the integration of ES in the proposed model effectively improves the wind power utilisation and the system efficiency.
Quality of experience aware multimedia communications over heterogeneous wireless networks
Authors: Pierre Setton
Published: March 2016

Quality of experience (QoE) has been a user‐centric performance metric for multimedia communications. Existing communication protocols over heterogeneous networks are mostly based on quality of service, which ignores the user satisfaction and subjective evaluation. In this paper, the authors propose a novel QoE‐aware multimedia communication framework for heterogeneous wireless networks. Specifically, the authors make three main contributions in this paper: (i) a general QoE model has been established by jointly characterising the multimedia applications and heterogeneous networks, (ii) the issue of multimedia communications over heterogeneous networks has been transformed as a stochastic optimisation problem, and (iii) the optimal solution is provided by designing a QoE‐aware multimedia scheduling scheme. Importantly, the proposed scheme is simply enough for online implementation. Numerical simulations have demonstrated the efficiency and robustness of the proposed scheme.
Study of the properties of liquid crystals modified by nanoparticles
Authors: Kalashnikov S. V. , Romanov N. A. , Nomoev A. V.
Published: March 2016

The dielectric anisotropy and the response time of polymer-dispersed liquid-crystal films mixed with various nanoparticles were measured. The different types of nanoparticles used included metallic, dielectric, and biphasic core-shell or Janus type nanoparticles. Two methods were used for the determination of the dielectric anisotropy: a bridge method and a current-voltage method. The dipole moments of the nanoparticles were measured by the method of diluted solutions (Debye method). It was shown that the dielectric anisotropy plays a crucial role in the electro-optical properties of modified liquid crystals which in turn depend on the dipole moment and thus on the physical nature of the introduced nanoparticles.
The interplay of covalency, hydrogen bonding, and dispersion leads to a long range chiral network: The example of 2-butanol
Authors: Liriano Melissa L. , Carrasco Javier , Lewis Emily A. , Murphy Colin J. , Lawton Timothy J. , Marcinkowski Matthew D. , Therrien Andrew J. , Michaelides Angelos , Sykes E. Charles H.
Published: March 2016

The assembly of complex structures in nature is driven by an interplay between several intermolecular interactions, from strong covalent bonds to weaker dispersion forces. Understanding and ultimately controlling the self-assembly of materials requires extensive study of how these forces drive local nanoscale interactions and how larger structures evolve. Surface-based self-assembly is particularly amenable to modeling and measuring these interactions in well-defined systems. This study focuses on 2-butanol, the simplest aliphatic chiral alcohol. 2-butanol has recently been shown to have interesting properties as a chiral modifier of surface chemistry; however, its mode of action is not fully understood and a microscopic understanding of the role non-covalent interactions play in its adsorption and assembly on surfaces is lacking. In order to probe its surface properties, we employed high-resolution scanning tunneling microscopy and density functional theory (DFT) simulations. We found a surprisingly rich degree of enantiospecific adsorption, association, chiral cluster growth and ultimately long range, highly ordered chiral templating. Firstly, the chiral molecules acquire a second chiral center when adsorbed to the surface via dative bonding of one of the oxygen atom lone pairs. This interaction is controlled via the molecule’s intrinsic chiral center leading to monomers of like chirality, at both chiral centers, adsorbed on the surface. The monomers then associate into tetramers via a cyclical network of hydrogen bonds with an opposite chirality at the oxygen atom. The evolution of these square units is surprising given that the underlying surface has a hexagonal symmetry. Our DFT calculations, however, reveal that the tetramers are stable entities that are able to associate with each other by weaker van der Waals interactions and tessellate in an extended square network. This network of homochiral square pores grows to cover the whole Au(111) surface. Our data reveal that the chirality of a simple alcohol can be transferred to its surface binding geometry, drive the directionality of hydrogen-bonded networks and ultimately extended structure. Furthermore, this study provides the first microscopic insight into the surface properties of this important chiral modifier and provides a well-defined system for studying the network’s enantioselective interaction with other molecules.
Dynamic stall of an experimental wind turbine blade
Authors: Melius Matthew , Cal Raúl Bayoán , Mulleners Karen
Published: March 2016

To understand the complex flow phenomena over wind turbine blades during stall development, a scaled three-dimensional non-rotating blade model is designed to be dynamically similar to a rotating full-scale NREL 5 MW wind turbine blade. A time-resolved particle image velocimetry (PIV) investigation of flow behavior during the stall cycle examines the processes of stall development and flow reattachment. Proper orthogonal decomposition (POD) and vortex detection techniques are applied to the PIV fields to quantify relevant flow characteristics such as vortex size, separation angle, and separation point throughout a dynamic pitching cycle. The behavior of the POD coefficients provides time scales for the transitional stages which are quantified and compared, revealing that transition from attached flow to full stall is delayed to higher angles of attack and occurs at a higher rate than the transition from full stall to attached flow. The instantaneous flow fields are then reconstructed using the first four POD modes to demonstrate their prominent roles throughout the stall cycle and their ability to capture the general separation behavior over the blade surface.
Rising motion of a single bubble through a liquid metal in the presence of a horizontal magnetic field
Authors: Zhang Jie , Ni Ming-Jiu , Moreau René
Published: March 2016

After a previous investigation of the rising motion of a gas bubble in a liquid metal under the influence of a vertical magnetic field, this new study focuses on the case of a uniform horizontal magnetic field. The numerical code is still the same: it is based on a volume-of-fluid technique and on an unstructured Cartesian adaptive grid system. A consistent and conservative scheme is adopted to compute the induced current density and the Lorentz force. In order to allow a benchmark, most of the parameters selected for this new investigation are the same as in an experiment recently performed in Dresden, Germany. The Ar bubble diameter is either 4.3 mm or 6.4 mm, the liquid metal is GaInSn, resulting in Reynolds numbers (Re) larger than in experiments with water (2000 to 4000, instead of 1000 or less) and allowing significant differences even without any magnetic field. In this paper, the magnetic field strength and therefore the interaction parameter are extended to values higher than in the experiment to provide data on the asymptotic behavior when these parameters get very large. The influence of the horizontal magnetic field on properties as the terminal rising velocity, the observed modifications of the rising paths, the shape of the bubble, and the wake structure is displayed and discussed. It is shown that the unstable bubble trajectory is closely related to the wake instability, which is itself strongly influenced by the horizontal magnetic field. When comparing the results with those obtained in the presence of a vertical magnetic field, significant differences appear together with the lack of axial symmetry, such as a slower rising motion of the bubble and the suppression of the “secondary path instability.” Increasing the intensity of the magnetic field results in an approximate exponential law to describe how the terminal rising velocity is reduced. The numerical predictions are interpreted in terms of the predominant physical mechanisms.
Wave blocking phenomenon of surface waves on a shear flow with a constant vorticity
Authors: Maïssa Philippe , Rousseaux Germain , Stepanyants Yury
Published: March 2016

Propagation of gravity-capillary surface waves on a background shear flow with a constant vorticity is studied and compared with the case when the background flow is uniform in depth. Under the assumption that the background flow gradually varies in the horizontal direction, the primary attention is paid to the wave blocking phenomenon; the effect of vorticity on this phenomenon is studied in detail. The conditions for wave blocking are obtained and categorized for different values of the governing dimensionless parameters: Froude number, dimensionless vorticity, and surface tension.
Critical conditions for the buoyancy-driven detachment of a wall-bound pendant drop
Authors: Lamorgese A. , Mauri R.
Published: March 2016

We investigate numerically the critical conditions for detachment of an isolated, wall-bound emulsion droplet acted upon by surface tension and wall-normal buoyancy forces alone. To that end, we present a simple extension of a diffuse-interface model for partially miscible binary mixtures that was previously employed for simulating several two-phase flow phenomena far and near the critical point [A. G. Lamorgese et al. “Phase-field approach to multiphase flow modeling,” Milan J. Math. 79(2), 597–642 (2011)] to allow for static contact angles other than 90°. We use the same formulation of the Cahn boundary condition as first proposed by Jacqmin [“Contact-line dynamics of a diffuse fluid interface,” J. Fluid Mech. 402, 57–88 (2000)], which accommodates a cubic (Hermite) interpolation of surface tensions between the wall and each phase at equilibrium. We show that this model can be successfully employed for simulating three-phase contact line problems in stable emulsions with nearly immiscible components. We also show a numerical determination of critical Bond numbers as a function of static contact angle by phase-field simulation.
Non-equilibrium modeling of UV laser induced plasma on a copper target in the presence of Cu2+
Authors: Ait Oumeziane Amina , Liani Bachir , Parisse Jean-Denis
Published: March 2016

This work is a contribution to the understanding of UV laser ablation of a copper sample in the presence of Cu2+ species as well as electronic non-equilibrium in the laser induced plasma. This particular study extends a previous paper and develops a 1D hydrodynamic model to describe the behavior of the laser induced plume, including the thermal non-equilibrium between electrons and heavy particles. Incorporating the formation of doubly charged ions (Cu2+) in such an approach has not been considered previously. We evaluate the effect of the presence of doubly ionized species on the characteristics of the plume, i.e., temperature, pressure, and expansion velocity, and on the material itself by evaluating the ablation depth and plasma shielding effects. This study evaluates the effects of the doubly charged species using a non-equilibrium hydrodynamic approach which comprises a contribution to the understanding of the governing processes of the interaction of ultraviolet nanosecond laser pulses with metals and the parameter optimization depending on the intended application.
The propagation of particulate gravity currents in a V-shaped triangular cross section channel: Lock-release experiments and shallow-water numerical simulations
Authors: Mériaux C. A. , Zemach T. , Kurz-Besson C. B. , Ungarish M.
Published: March 2016

In this study, we investigate the motion of particulate gravity currents in a horizontal V-shaped channel. The particulate currents consisted of particles whose size varied between 0 and 100 μm but whose mean size increased. Particles were poorly sorted as the variance of the grain size distributions varied between 50 and 200. While the phases of propagation of homogeneous currents in such a geometry have been studied in the literature, this study considers the effects of the grain size on the propagation. The distance of propagation and front velocity of full-depth high-Reynolds-number lock-release experiments and shallow-water equation simulations were analyzed as the mean grain size of the initial particle distributions, defined by mass, was increased from 19 to 58 μm. Similar to the homogeneous currents, three consecutive phases of the front velocity could be identified but their characteristics and extent depend on the particle size. The initial phase, in particular, depends on a dimensionless settling number β that is defined as the ratio of two characteristic time scales, the propagation time x0/U, where U is the scale for the front speed and x0 the lock length, and the settling time h0/vs, where vs is the scale for the settling velocity and h0 the initial height of the current. For dimensionless settling numbers less than 0.001, the initial phase is characterized by a constant velocity for over about 6-7 lock lengths that is alike the initial slumping phase of perfectly constant velocity of the homogeneous currents. For dimensionless settling numbers greater than 0.001 and less than 0.015, the initial phase is no longer characterized by a constant velocity but an almost constant velocity for over about a similar 6-7 lock lengths. For dimensionless settling numbers greater than 0.015, however, as such, this phase is no longer seen. This initial phase is followed by a continuous decrease of the front advance, which results from the sedimentation of the particles. Unlike the homogeneous currents, this phase is a non-self-similar propagation. This phase is ended by a viscosity-dominated phase appearing to vary as ∼t1/7. The good agreement between the front advance of the experiments and shallow-water equation simulations demonstrates that the mean size by mass is a fairly good proxy of poorly sorted particles.
Entanglement-saving channels
Authors: Lami L. , Giovannetti V.
Published: March 2016

The set of Entanglement Saving (ES) quantum channels is introduced and characterized. These are completely positive, trace preserving transformations which when acting locally on a bipartite quantum system initially prepared into a maximally entangled configuration, preserve its entanglement even when applied an arbitrary number of times. In other words, a quantum channel ψ is said to be ES if its powers ψn are not entanglement-breaking for all integers n. We also characterize the properties of the Asymptotic Entanglement Saving (AES) maps. These form a proper subset of the ES channels that is constituted by those maps that not only preserve entanglement for all finite n but which also sustain an explicitly not null level of entanglement in the asymptotic limit n → ∞. Structure theorems are provided for ES and for AES maps which yield an almost complete characterization of the former and a full characterization of the latter.
Leak path passivation by in situ Al-N for InGaN solar cells operating at wavelengths up to 570 nm
Authors: Wang Ke , Imai Daichi , Kusakabe Kazuhide , Yoshikawa Akihiko
Published: March 2016

A leak path passivation (LPP) technology for InGaN solar cells with photo-response up to 570 nm was developed by inserting in situ monolayers of Al-N into active layers. The InGaN layer in the passivated sample is partially relaxed and incorporates more than 23.5% In. By adopting in situ Al-N LPP, the open circuit voltage increases from 0.96 V to 1.35 V under one sun illumination (1.45–1.68 V under 72 suns), and the dark shunt resistance increases from 3.6 kΩ cm2 to 12.6 kΩ cm2, leading to an increase in power conversion efficiency by a factor of 2.0–2.26 (1–72 suns). This in situ Al-N LPP approach paves a way to exploit the full potential of InGaN for high efficiency solar cell application, accepting the reality of defective high-In-content thick and relaxed InGaN.
The effect of particle density in turbulent channel flow laden with finite size particles in semi-dilute conditions
Authors: Fornari W. , Formenti A. , Picano F. , Brandt L.
Published: March 2016

We study the effect of varying the mass and volume fraction of a suspension of rigid spheres dispersed in a turbulent channel flow. We performed several direct numerical simulations using an immersed boundary method for finite-size particles changing the solid to fluid density ratio R, the mass fraction χ, and the volume fraction ϕ. We find that varying the density ratio R between 1 and 10 at constant volume fraction does not alter the flow statistics as much as when varying the volume fraction ϕ at constant R and at constant mass fraction. Interestingly, the increase in overall drag found when varying the volume fraction is considerably higher than that obtained for increasing density ratios at same volume fraction. The main effect at density ratios R of the order of 10 is a strong shear-induced migration towards the centerline of the channel. When the density ratio R is further increased up to 1000, the particle dynamics decouple from that of the fluid. The solid phase behaves as a dense gas and the fluid and solid phase statistics drastically change. In this regime, the collision rate is high and dominated by the normal relative velocity among particles.
On the Davey-Stewartson system with competing nonlinearities
Authors: Zhu Shihui
Published: March 2016

This paper is concerned with the blow-up solutions for the Davey-Stewartson system with competing nonlinearities, which results in the loss of scaling invariance. The best constant of a new gG-N type inequality is given to find the sharp threshold mass of blow-up and global existence. Moreover, under the sharp threshold mass, the dynamical behavior of blow-up solutions is investigated, including L2-concentration, L2 weak limits, and limiting profile.
Co on Fe3O4(001): Towards precise control of surface properties
Authors: Gargallo-Caballero Raquel , Martín-García Laura , Quesada Adrián , Granados-Miralles Cecilia , Foerster Michael , Aballe Lucía , Bliem Roland , Parkinson Gareth S. , Blaha Peter , Marco José F. , de la Figuera Juan
Published: March 2016

A novel approach to incorporate cobalt atoms into a magnetite single crystal is demonstrated by a combination of x-ray spectro-microscopy, low-energy electron diffraction, and density-functional theory calculations. Co is deposited at room temperature on the reconstructed magnetite (001) surface filling first the subsurface octahedral vacancies and then occupying adatom sites on the surface. Progressive annealing treatments at temperatures up to 733 K diffuse the Co atoms into deeper crystal positions, mainly into octahedral ones with a marked inversion level. The oxidation state, coordination, and magnetic moments of the cobalt atoms are followed from their adsorption to their final incorporation into the bulk, mostly as octahedral Co2+. This precise control of the near-surface Co atoms location opens up the way to accurately tune the surface physical and magnetic properties of mixed spinel oxides.
Soft x-ray ptychography studies of nanoscale magnetic and structural correlations in thin SmCo5 films
Authors: Shi X. , Fischer P. , Neu V. , Elefant D. , Lee J. C. T. , Shapiro D. A. , Farmand M. , Tyliszczak T. , Shiu H.-W. , Marchesini S. , Roy S. , Kevan S. D.
Published: March 2016

High spatial resolution magnetic x-ray spectromicroscopy at x-ray photon energies near the cobalt L3 resonance was applied to probe an amorphous 50 nm thin SmCo5 film prepared by off-axis pulsed laser deposition onto an x-ray transparent 200 nm thin Si3N4 membrane. Alternating gradient magnetometry shows a strong in-plane anisotropy and an only weak perpendicular magnetic anisotropy, which is confirmed by magnetic transmission soft x-ray microscopy images showing over a field of view of 10 μm a primarily stripe-like domain pattern but with local labyrinth-like domains. Soft x-ray ptychography in amplitude and phase contrast was used to identify and characterize local magnetic and structural features over a field of view of 1 μm with a spatial resolution of about 10 nm. There, the magnetic labyrinth domain patterns are accompanied by nanoscale structural inclusions that are primarily located in close proximity to the magnetic domain walls. Our analysis suggests that these inclusions are nanocrystalline Sm2Co17 phases with nominally in-plane magnetic anisotropy.
Two-plasmon-decay driven by an extraordinary electromagnetic wave in a magnetized plasma with nonextensive distribution
Authors: Qiu Hui-Bin , Song Hai-Ying , Liu Shi-Bing
Published: March 2016

Two-Plasmon-Decay (TPD) driven by an extraordinary electromagnetic wave in a magnetized plasma with nonextensive distribution has been investigated theoretically when electron-ion collision and term ωp2E are taken into account. The analytical expression of the growth rate has been obtained, which reproduces the result in the context of Maxwellian distribution in the extensive limit. It has been shown that nonextensive nature of electron distribution, the external magnetic field, laser pump amplitude, and the term ωp2E have promoting effect on the instability growth rate of TPD, but the electron-ion collision has depressing effect on the instability growth rate.
Dynamics of cathode spots in low-pressure arc plasma removing oxide layer on steel surfaces
Authors: Tang Z. L. , Yang K. , Liu H. X. , Zhang Y. C. , Li H. , Zhu X. D.
Published: March 2016

The dynamics of cathode spots has been investigated in low-pressure arc plasma for removing oxide layer on low carbon steel surfaces. The motion of cathode spots was observed with a high speed camera, and the arc voltage was analyzed by fast Fourier transform. The spots move on clean steel surface as a random walk, and the low-frequency components dominated the voltage waveform. However, the spots on steel surfaces with oxide layer tend to burn on the rim of the eroded area formed in the previous arcing, and the low-frequency components decrease correspondingly. The “color” of the colored random noise for arc voltage varies from the approximate brown noise for clean steel surface to pink noise for thick oxide layer, where the edge effect of boundary is considered to play a significant role.
One-way-coupling simulation of cavitation accompanied by high-speed droplet impact
Authors: Kondo Tomoki , Ando Keita
Published: March 2016

Erosion due to high-speed droplet impact is a crucial issue in industrial applications. The erosion is caused by the water-hammer loading on material surfaces and possibly by the reloading from collapsing cavitation bubbles that appear within the droplet. Here, we simulate the dynamics of cavitation bubbles accompanied by high-speed droplet impact against a deformable wall in order to see whether the bubble collapse is violent enough to give rise to cavitation erosion on the wall. The evolution of pressure waves in a single water (or gelatin) droplet to collide with a deformable wall at speed up to 110 m/s is inferred from simulations of multicomponent Euler flow where phase changes are not permitted. Then, we examine the dynamics of cavitation bubbles nucleated from micron/submicron-sized gas bubble nuclei that are supposed to exist inside the droplet. For simplicity, we perform Rayleigh–Plesset-type calculations in a one-way-coupling manner, namely, the bubble dynamics are determined according to the pressure variation obtained from the Euler flow simulation. In the simulation, the preexisting bubble nuclei whose size is either micron or submicron show large growth to submillimeters because tension inside the droplet is obtained through interaction of the pressure waves and the droplet interface; this supports the possibility of having cavitation due to the droplet impact. It is also found, in particular, for the case of cavitation arising from very small nuclei such as nanobubbles, that radiated pressure from the cavitation bubble collapse can overwhelm the water-hammer pressure directly created by the impact. Hence, cavitation may need to be accounted for when it comes to discussing erosion in the droplet impact problem.
Axial stress localization facilitates pressure propagation in gelled pipes
Authors: Norrman Jens , Skjæraasen Olaf , Oschmann Hans-Jörg , Paso Kristofer , Sjöblom Johan
Published: March 2016

Paraffin wax-oil gels are unique rheological fluids which undergo shear degradation starting at a deformation (shear strain level) of approximately 1%. Flow commencement in pipelines filled with wax-oil gels is a complex hydrodynamic process involving propagation of acoustic, diffusive, and rheological degradation pressure wave fronts. Dynamic simulation informed by qualified rheological relations provides useful insight into the physical nature of these flow processes. Eulerian simulations are presented which emulate known physical phenomena and essential characteristics of wax-gel flow dynamics. A constitutive rheological equation set accounts for deformation-driven reduction in yield stress and viscosity terms. No explicit time-dependent rheological parameters are utilized in the equations. Rheological yielding alters the nature of the dominant pressure wave from inherently diffusive towards self-sharpening. Axial stress localization effectively sequentializes the gel breakage process, quantified by reduced length of the pressure wave-front zone. Ultimately, axial stress localization allows flow in longer pipe segments, albeit with a concomitant time delay. Viscous behavior and yielding degradation behavior are shown to account for upward and downward concavity in transient axial pressure profiles, respectively. Overall, a unique synergy between gel compressibility and gel degradation is revealed. Deformation-coupled interaction between compressibility and degradation allows pressure propagation and subsequent sustained flow through a gel material which is otherwise immobile in the incompressible case.
Electrostatic surface waves on a magnetized quantum plasma half-space
Authors: Moradi Afshin
Published: March 2016

A theory of electrostatic surface waves on a quantum plasma half-space is developed with the inclusion of external magnetic field effects for the geometry in which the magnetic field is parallel to the surface and the direction of propagation is perpendicular to the magnetic field. A general analytical expression for dispersion relation of surface waves is obtained by solving Poisson and quantum magnetohydrodynamic equations with appropriate quantum boundary conditions.
Prospects for quantum computing with an array of ultracold polar paramagnetic molecules
Authors: Karra Mallikarjun , Sharma Ketan , Friedrich Bretislav , Kais Sabre , Herschbach Dudley
Published: March 2016

Arrays of trapped ultracold molecules represent a promising platform for implementing a universal quantum computer. DeMille [Phys. Rev. Lett. 88, 067901 (2002)] has detailed a prototype design based on Stark states of polar 1Σ molecules as qubits. Herein, we consider an array of polar 2Σ molecules which are, in addition, inherently paramagnetic and whose Hund’s case (b) free-rotor pair-eigenstates are Bell states. We show that by subjecting the array to combinations of concurrent homogeneous and inhomogeneous electric and magnetic fields, the entanglement of the array’s Stark and Zeeman states can be tuned and the qubit sites addressed. Two schemes for implementing an optically controlled CNOT gate are proposed and their feasibility discussed in the face of the broadening of spectral lines due to dipole-dipole coupling and the inhomogeneity of the electric and magnetic fields.
Particle-in-cell simulations of collisionless magnetic reconnection with a non-uniform guide field
Authors: Wilson F. , Neukirch T. , Hesse M. , Harrison M. G. , Stark C. R.
Published: March 2016

Results are presented of a first study of collisionless magnetic reconnection starting from a recently found exact nonlinear force-free Vlasov–Maxwell equilibrium. The initial state has a Harris sheet magnetic field profile in one direction and a non-uniform guide field in a second direction, resulting in a spatially constant magnetic field strength as well as a constant initial plasma density and plasma pressure. It is found that the reconnection process initially resembles guide field reconnection, but that a gradual transition to anti-parallel reconnection happens as the system evolves. The time evolution of a number of plasma parameters is investigated, and the results are compared with simulations starting from a Harris sheet equilibrium and a Harris sheet plus constant guide field equilibrium.
Lagrangian properties of the entrainment across turbulent/non-turbulent interface layers
Authors: Watanabe Tomoaki , da Silva Carlos B. , Sakai Yasuhiko , Nagata Koji , Hayase Toshiyuki
Published: March 2016

Lagrangian statistics obtained from direct numerical simulations of turbulent planar jets and mixing layers are reported for the separation distance between the tracer particles at the outer edge of the turbulent/non-turbulent interface layer, and the entrained fluid particles. In the viscous superlayer (VSL) the mean square particle distance exhibits a ballistic evolution, while the Richardson-like scaling for relative dispersion prevails inside the turbulent sublayer (TSL). The results further support the existence of two different regimes within the interface layer, where small-scale outward enstrophy diffusion governs the entrained particles in the VSL, while inviscid small-scale motions govern the TSL.
Angle-resolved diffraction grating biosensor based on porous silicon
Authors: Lv Changwu , Jia Zhenhong , Liu Yajun , Mo Jiaqing , Li Peng , Lv Xiaoyi
Published: March 2016

In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.
Long wavelength stimulated emission up to 9.5 μm from HgCdTe quantum well heterostructures
Authors: Morozov S. V. , Rumyantsev V. V. , Kadykov A. M. , Dubinov A. A. , Kudryavtsev K. E. , Antonov A. V. , Mikhailov N. N. , Dvoretskii S. A. , Gavrilenko V. I.
Published: March 2016

Stimulated emission from waveguide HgCdTe structures with several quantum wells inside waveguide core is demonstrated at wavelengths up to 9.5 μm. Photoluminescence line narrowing down to kT energy, as well as superlinear rise in its intensity evidence the onset of the stimulated emission, which takes place under optical pumping with intensity as small as ∼0.1 kW/cm2 at 18 K and 1 kW/cm2 at 80 K. One can conclude that HgCdTe structures potential for long-wavelength lasers is not exhausted.
Reversibly tunable coupled and decoupled super absorbing structures
Authors: Zhang Nan , Dong Ziye , Ji Dengxin , Song Haomin , Zeng Xie , Liu Zhejun , Jiang Suhua , Xu Yun , Bernussi Ayrton , Li Wei , Gan Qiaoqiang
Published: March 2016

We differentiate the spacer-dependent peak shift in coupled and decoupled super absorbing structures based on magnetic resonance and interference mechanism, respectively, which is experimentally validated by low-cost and large-area structures fabricated using lithography-free processes. The reversible real-time spectral tunability is then demonstrated by incorporating a thermally tunable polymeric spacer layer.
Spin-state transition induced half metallicity in a cobaltate from first principles
Authors: Ou Xuedong , Fan Fengren , Li Zhengwei , Wang Hongbo , Wu Hua
Published: March 2016

Half metal is a promising spintronic material. Here, we explore, using first principles calculations, a spin-state transition induced half metallicity in a layered cobaltate via a physical or chemical pressure. Our exemplary first principles study shows that the layered cobaltate Sr2CoO3F would undergo a transition, under a pressure of 5.4 GPa, from a high-spin antiferromagnetic insulator to an intermediate-spin ferromagnetic half-metal. The former phase is associated with a superexchange in a Mott insulator, and the latter one is due to a broad band formation and a kinetic energy gain of the partially occupied eg orbital. Note that the above transition could also be induced by a chemical pressure via doping in (Sr1−xCax)2CoO3F (x > 0.3). This work suggests that a cobaltate would be of a particular interest if stabilized into an intermediate-spin state.
Nanoscale heat transfer in the head-disk interface for heat assisted magnetic recording
Authors: Wu Haoyu , Xiong Shaomin , Canchi Sripathi , Schreck Erhard , Bogy David
Published: March 2016

Laser heating has been introduced in heat-assisted magnetic recording in order to reduce the magnetic coercivity and enable data writing. However, the heat flow inside a couple of nanometers head-disk gap is still not well understood. An experimental stage was built for studying heat transfer in the head-disk interface (HDI) and the heat-induced instability of the HDI. A laser heating system is included to produce a heated spot on the disk at the position of the slider. A floating air bearing slider is implemented in the stage for sensing the temperature change of the slider due to the heat transfer from the disk by the use of an embedded contact sensor, and the gap between the two surfaces is controlled by the use of a thermal fly-height control actuator. By using this system, we explore the dependency of the heat transfer on the gap spacing as well as the disk temperature.
Anti-phase boundaries at the SrTiO3/Si(001) interface studied using aberration-corrected scanning transmission electron microscopy
Authors: Wu HsinWei , Aoki Toshihiro , Posadas Agham B. , Demkov Alexander A. , Smith David J.
Published: March 2016

In this work, the atomic structure of anti-phase boundary defects at the SrTiO3/Si (001) interface is investigated by aberration-corrected scanning transmission electron microscopy. Atomic-resolution images reveal an abrupt SrTiO3/Si interface with no intermediate oxide layer. Both single and double Si atomic columns (“dumbbells”) from different terraces of the Si(001) surface are visible at the interface. Anti-phase boundaries (APB) consisting of two adjacent TiO2 planes in the SrTiO3 (STO) film resulting either from Si surface steps or from the merging of crystalline domains from different surface nucleation sites are identified. These APBs occur on either {110} or {010} planes and both types have displacement vectors of aSTO/2⟨110⟩.
Direct growth of graphene on SiC(0001) by KrF-excimer-laser irradiation
Authors: Hattori Masakazu , Ikenoue Hiroshi , Nakamura Daisuke , Furukawa Kazuaki , Takamura Makoto , Hibino Hiroki , Okada Tatsuo
Published: March 2016

In this report, we propose a direct patterning method of graphene on the SiC(0001) surface by KrF-excimer-laser irradiation. In this method, Si atoms are locally sublimated from the SiC surface in the laser-irradiated area, and direct graphene growth is induced by the rearrangement of surplus carbon on the SiC surface. Using Raman microscopy, we demonstrated the formation of graphene by laser irradiation and observed the growth process by transmission electron microscopy and conductive atomic force microscopy. When SiC was irradiated by 5000 shots of the laser beam with a fluence of 1.2 J/cm2, two layers of graphene were synthesized on the SiC(0001) surface. The number of graphene layers increased from 2 to 5–7 with an increase in the number of laser shots. Based on the results of conductive-atomic force microscopy measurements, we conclude that graphene formation was initiated from the step area, after which the graphene grew towards the terrace area by further Si evaporation and C recombination with increasing laser irradiation.
Extension of filament propagation in water with Bessel-Gaussian beams
Authors: Kaya G. , Kaya N. , Sayrac M. , Boran Y. , Strohaber J. , Kolomenskii A. A. , Amani M. , Schuessler H. A.
Published: March 2016

We experimentally studied intense femtosecond pulse filamentation and propagation in water for Bessel-Gaussian beams with different numbers of radial modal lobes. The transverse modes of the incident Bessel-Gaussian beam were created from a Gaussian beam of a Ti:sapphire laser system by using computer generated hologram techniques. We found that filament propagation length increased with increasing number of lobes under the conditions of the same peak intensity, pulse duration, and the size of the central peak of the incident beam, suggesting that the radial modal lobes may serve as an energy reservoir for the filaments formed by the central intensity peak.
Simple method for the growth of 4H silicon carbide on silicon substrate
Authors: Asghar M. , Shahid M. Y. , Iqbal F. , Fatima K. , Nawaz Muhammad Asif , Arbi H. M. , Tsu R.
Published: March 2016

In this study we report thermal evaporation technique as a simple method for the growth of 4H silicon carbide on p-type silicon substrate. A mixture of Si and C60 powder of high purity (99.99%) was evaporated from molybdenum boat. The as grown film was characterized by XRD, FTIR, UV-Vis Spectrophotometer and Hall Measurements. The XRD pattern displayed four peaks at 2Θ angles 28.550, 32.700, 36.100 and 58.900 related to Si (1 1 1), 4H-SiC (1 0 0), 4H-SiC (1 1 1) and 4H-SiC (2 2 2), respectively. FTIR, UV-Vis spectrophotometer and electrical properties further strengthened the 4H-SiC growth.
A review of factors influencing key biological components of maternal productivity in temperate beef cattle
Authors: Walmsley B. J. , Lee S. J. , Parnell P. F. , Pitchford W. S.
Published: March 2016

Cow–calf efficiency or maternal productivity is highly correlated with total system efficiency of beef production. Balancing the needs of the cow herd with other production components is a daily challenge beef producers address to maximise the number of calves born and raised to weaning and, in turn, maximise maternal productivity. Pressure to satisfy modern consumer needs has shifted selection emphasis to production traits at the expense of fitness traits allowing adaptability to decline. Balancing the needs of the cow herd with production objectives presents cow–calf producers with the challenge of genetically tailoring their cattle to modern needs, while sustainably managing these cattle and natural resources. This balancing act is highlighted by the debate surrounding the application of residual feed intake to reduce costs associated with provision of feed for beef production. Some uncertainty surrounds the relationships between efficiency, production and maternal productivity traits. This review examines key components and definitions of maternal productivity. Management decisions as well as cow and calf traits have important interacting impacts on maternal productivity. Achieving a calving interval of 365 days represents the single most important production issue affecting maternal productivity and is dependent on heifer development during early life and energy reserves (i.e. body condition score) in subsequent years. Management issues such as calving date and selection decisions interact with environmental factors such as photoperiod and production traits such as feed intake, and previous production levels, to influence heifer development and cow body energy reserves. Some proposed definitions of maternal productivity simply include weaning weight per cow mated which can be averaged over all progeny weaned during a cow’s lifetime. Ideally, a definition should include the inputs and outputs of maternal productivity. Some definitions express maternal productivity over large time scales, e.g. a cow’s productive lifetime. Most definitions focus on the cow–calf unit, while some include progeny growth and feed intake to slaughter. This review recommends a definition that focuses on the cow–calf unit, as follows: (weight of calf weaned and cow weight change)/(metabolisable energy intake per cow and calf unit). This definition has the capacity to be scaled up, to include progeny postweaning production, as well as being applicable over varying time scales (e.g. 1 year to a cow’s whole productive life). Improvements in all facets of maternal productivity using this definition can be expected to improve beef-production efficiency.
Physiological factors determine the accumulation of D-glycero-D-ido-octulose (D-g-D-i-oct) in the desiccation tolerant resurrection plant Craterostigma plantagineum
Authors: Zhang Qingwei , Bartels Dorothea
Published: March 2016

The relationship between the accumulation of D-glycero-D-ido-octulose (D-g-D-i-oct) and sucrose and desiccation tolerance was analysed in leaves of Craterostigma plantagineum Hochst. in various conditions. The D-g-D-i-oct level is strictly controlled in C. plantagienum. Light is an important factor enhancing D-g-D-i-oct synthesis when exogenous sucrose is supplied. Desiccation tolerance is lost during natural senescence and during sugar starvation that leads to senescence. The differences in expression patterns of senescence-related genes and the carbohydrate status between vigorous and senescent plants indicate that desiccation tolerance and accumulation of octulose in C. plantagineum is dependent on the developmental stage. Sucrose synthesis is affected more by dehydration than by senescence. D-g-D-i-oct has superior hydroxyl scavenging ability to other common sugars accumulating in C. plantagineum. In the presence of reactive oxygen species (ROS) D-g-D-i-oct levels decreased, probably as a defence reaction.
Architectural transitions in
Vibrio cholerae
biofilms at single-cell resolution
Authors: Drescher Knut , Dunkel Jörn , Nadell Carey D. , van Teeffelen Sven , Grnja Ivan , Wingreen Ned S. , Stone Howard A. , Bassler Bonnie L.
Published: March 2016

Significance

Bacterial biofilms are ubiquitous in the environment and serve beneficial roles in microbiota communities in the context of eukaryotic hosts and in industrial applications, yet biofilms of pathogenic bacteria can also cause devastating infections. Biofilm architectures are usually studied at a coarse morphological level, and consequently, little is known about the internal biofilm architecture and how it emerges. Here, we use an optical imaging technique to visualize every cell inside thousands of
Vibrio cholerae
biofilms to discover architectural transitions and the major phases of
V. cholerae
biofilm growth.
Effect and potential mechanism of action of sea cucumber saponins on postprandial blood glucose in mice
Authors: Fu Xueyuan , Wen Min , Han Xiuqing , Yanagita Teruyoshi , Xue Yong , Wang Jingfeng , Xue Changhu , Wang Yuming
Published: March 2016

Postprandial blood glucose control is the major goal in the treatment of diabetes. Here, we investigated the effect of sea cucumber saponins (SCSs) on postprandial blood glucose levels. SCS inhibited yeast as well as rat intestinal α-glucosidase activity in a dose-dependent manner and showed better inhibition of yeast α-glucosidases compared to the positive control. Further studies were performed using ICR mice treated with SCS and starch or SCS alone by oral gavage. Unexpectedly, SCS increased postprandial blood glucose levels a short time (1 h) after oral gavage. The serum corticosterone (CORT) level showed a consistent correlation with glucose levels. In vitro experiments confirmed that SCS treatment increased the secretion of CORT in the Y1 adrenal cell line. Overall, these studies demonstrated that SCS gavage could inhibit α-glucosidase activity but cannot attenuate postprandial blood glucose level within short time periods. The underlying mechanisms are probably related to increased serum CORT levels.
Molecular characterization and expression of metallothionein from freshwater pearl mussel, Hyriopsis schlegelii
Authors: Wang Chengyuan , Sheng Junqing , Hong Yijiang , Peng Kou , Wang Junhua , Wu Di , Shi Jianwu , Hu Beijuan
Published: March 2016

Two metallothionein genes (HsMT1 and HsMT2) were first identified and described from Hyriopsis schlegelii. The open reading frame of HsMT1 and HsMT2 were 216 and 222 bp, encoding a protein of 71 and 73 amino acid residues. The deduced amino acid sequences showed they contained parts of typical MT characteristics, apart from HsMT2 lacked Cys–Cys motifs. The phylogenetic tree showed HsMT1 shared a high similarity with that of other molluscs, but HsMT2 was split into a distinct group separated from known molluscan MTs. HsMT1 exhibited constitutive expression in all examined tissues and the highest expression occurred in hepatopancreas, however, nearly all HsMT2 was just detected in gonad. After Cd exposure, their mRNA levels presented similar expression patterns. The transgenic bacteria of HsMT1 showed higher tolerance than HsMT2 in Cd environment. It was implied that HsMT1 and HsMT2 were involved in metal response but HsMT2 might have other physiological functions.
National income inequality and self-rated health: the differing impact of individual social trust across 89 countries
Authors: Rözer Jesper , Kraaykamp Gerbert , Huijts Tim
Published: March 2016

The well-known Income Inequality Hypothesis suggests that income disparities in a country are detrimental for people's health. Empirical studies testing this hypothesis so far have found mixed results. In this study, we argue that a reason for these mixed findings may be that high national income inequality mostly harms individuals with high levels of social trust. We employ data of the World Value Survey and European Value Survey, using information on 393,761 respondents within 89 countries. Multilevel regression analyses, across countries and within countries across time, confirm findings from earlier studies that there is a negative association between national income inequality and self-rated health. Our results also reveal that national income inequality is especially detrimental for trustful citizens: while the effect of income inequality is nearly absent among people with low social trust it is negative among people with high social trust.