bluuebunny/crossref_metadata_2025 huggingface dataset:
Thiosemicarbazide chemical functionalized carbon dots as a fluorescent nanosensor for sensing Cu2+and intracellular imaging
Authors: Fu Zheng , Cui Fengling
Published: June 2016

Synthesis procedures for the CDs-based nanosensor and schematic diagram of Cu2+detection.
Investigation of biological cell–small molecule interactions with a gold surface plasmon resonance sensor using a laser scanning confocal imaging-surface plasmon resonance system
Authors: Liu Sha , Zhang Hongyan , Liu Weimin , Zhou Bingjiang , Ma Qian , Ge Jiechao , Wu Jiasheng , Wang Pengfei
Published: June 2016

In our work, we investigated the interactions between a small molecule, folic acid, and biological cells through the interaction of folic acid and folate receptors using a laser scanning confocal imaging-surface plasmon resonance (LSCI-SPR) system.
PGS@B–N: an efficient flame retardant to improve simultaneously the interfacial interaction and the flame retardancy of EVA
Authors: Yang Zhi-Wang , Liang Xi-Xi , Xu Xue-Qing , Lei Cheng , He Xin-li , Song Ting , Huo Wen-Yan , Ma Heng-Chang , Lei Zi-Qiang
Published: June 2016

EVA/PGS@B–N composites with suitable loadings of PGS@B–N particles have significantly improved flame retardancy.
Phosphorus and cobalt co-doped reduced graphene oxide bifunctional electrocatalyst for oxygen reduction and evolution reactions
Authors: Zheng Xiangjun , Yang Zhenrong , Wu Jiao , Jin Chao , Tian Jing-Hua , Yang Ruizhi
Published: June 2016

P and Co co-doped reduced graphene oxide has been developed and studied, which exhibits great potential in catalyzing not only oxygen reduction but also oxygen evolution, and can be used as a promising non-precious bifunctional electrocatalyst.
Facile synthesis of porous NiCo2O4 nanoflakes as magnetic recoverable catalysts towards the efficient degradation of RhB
Authors: Zhang Wenwen , Su Yi , Zhang Xuemei , Yang Ying , Guo Xiaohui
Published: June 2016

Flake-like NiCo2O4 was prepared via a facile chemical reaction process. The NiCo2O4/PMS heterogeneous catalysts can completely degrade RhB within 30 min and display excellent cycling durability.
Cu(i)-catalyzed multicomponent cascade reactions of terminal alkynes, unactivated primary alkyl bromides, CO2 and NaN3
Authors: Wu Fu-song , Tong Wei , Liang Ying , Wang Heng-shan , Teng Qing-hu , Pan Ying-ming
Published: June 2016

We have developed a mild, robust, and multicomponent cascade reaction for the synthesis of triazolo-fused dihydrooxazinones from terminal alkynes, unactivated primary alkyl bromides, carbon dioxide and sodium azide.
Layer-by-layer assembly of exfoliated layered double hydroxide nanosheets for enhanced electrochemical oxidation of water
Authors: Zhang Cong , Zhao Jingwen , Zhou Lei , Li Zhenhua , Shao Mingfei , Wei Min
Published: June 2016

Well-ordered (CoNi-LDH/Fe-PP)nultrathin films were obtained through a layer-by-layer technique, which exhibit largely enhanced OER performance.
N-doped WS2 nanosheets: a high-performance electrocatalyst for the hydrogen evolution reaction
Authors: Sun Changqi , Zhang Jingyan , Ma Ji , Liu Peitao , Gao Daqiang , Tao Kun , Xue Desheng
Published: June 2016

Non-Pt-based catalysts are urgently required to produce abundant hydrogen in electrochemical water splitting, in order to make the hydrogen evolution reaction (HER) feasible and energy efficient.
Optical analysis of CH3NH3SnxPb1−xI3 absorbers: a roadmap for perovskite-on-perovskite tandem solar cells
Authors: Anaya Miguel , Correa-Baena Juan P. , Lozano Gabriel , Saliba Michael , Anguita Pablo , Roose Bart , Abate Antonio , Steiner Ullrich , Grätzel Michael , Calvo Mauricio E. , Hagfeldt Anders , Míguez Hernán
Published: June 2016

We propose a novel tandem architecture design in which both top and bottom cells contain perovskite absorbers.
Upconversion nanocomposites for photo-based cancer theranostics
Authors: Wang Shuailiang , Bi Anyao , Zeng Wenbin , Cheng Zhen
Published: June 2016

Upconversion nanoparticles (UCNPs) are able to convert long wavelength excitation light into high energy ultraviolet (UV) or visible emissions, and they have attracted significant attention because of their distinct photochemical properties including sharp emission bands, low autofluorescence, high tissue penetration depth and minimal photodamage to tissues.
n-Type doped transparent conducting binary oxides: an overview
Authors: Dixon Sebastian C. , Scanlon David O. , Carmalt Claire J. , Parkin Ivan P.
Published: June 2016

A review covering recent developments in computational and experimental study in the n-type doping of binary oxide semiconductors for transparent conducting applications.
Regulatory principles in metabolism–then and now
Authors: Curi Rui , Newsholme Philip , Marzuca-Nassr Gabriel Nasri , Takahashi Hilton Kenji , Hirabara Sandro Massao , Cruzat Vinicius , Krause Mauricio , de Bittencourt Paulo Ivo Homem
Published: June 2016

The importance of metabolic pathways for life and the nature of participating reactions have challenged physiologists and biochemists for over a hundred years. Eric Arthur Newsholme contributed many original hypotheses and concepts to the field of metabolic regulation, demonstrating that metabolic pathways have a fundamental thermodynamic structure and that near identical regulatory mechanisms exist in multiple species across the animal kingdom. His work at Oxford University from the 1970s to 1990s was groundbreaking and led to better understanding of development and demise across the lifespan as well as the basis of metabolic disruption responsible for the development of obesity, diabetes and many other conditions. In the present review we describe some of the original work of Eric Newsholme, its relevance to metabolic homoeostasis and disease and application to present state-of-the-art studies, which generate substantial amounts of data that are extremely difficult to interpret without a fundamental understanding of regulatory principles. Eric's work is a classical example of how one can unravel very complex problems by considering regulation from a cell, tissue and whole body perspective, thus bringing together metabolic biochemistry, physiology and pathophysiology, opening new avenues that now drive discovery decades thereafter.
Adaptive imaging of anisotropic target based on circular‐SAR
Authors: Zhao Yue , Lin Yun , Hong Wen , Yu Lingjuan
Published: June 2016

The isotropic reflectivity assumption is a valid approximation in traditional narrow‐angle synthetic aperture radar (SAR). However, for large angular ranges most targets exhibit only limited scattering persistence. Therefore, this assumption is violated in circular‐SAR (CSAR). Thus, the performance of traditional fully coherent image formation is poor in CSAR, because coherent integration over the entire aperture will obscure aspect‐independent reflectivity characteristics. To address this problem, an adaptive imaging algorithm which accommodates anisotropic targets to improve image quality is proposed. The efficient use of valid azimuth angles can reduce noise and errors and highlight anisotropic targets in CSAR image. Another advantage of this algorithm is that the anisotropy target scattering behaviour can be extracted by data inversion in the imaging process. Compared with the sub‐aperture approach, which can also extract the anisotropic scattering properties of target, the data inversion approach in the algorithm can provide more accurate results and a finer curve. The adaptive imaging method is validated in this Letter by simulation and an airborne dataset.
Reconfigurable frequency selective surface for beam‐switching applications
Authors: Bouslama Moufida , Traii Moubarek , Denidni Tayeb Ahmed , Gharsallah Ali
Published: June 2016

A novel design for a beam‐switching antenna based on a new reconfigurable frequency selective surface (FSS) is presented at 2.1 GHz operating frequency. The antenna system consists of an omnidirectional antenna and a cylindrical FSS for controlling its radiation pattern characteristics. The discontinuous split‐ring resonator (SRR) cross‐shape FSS is composed of 12 FSS unit cells with 4 active elements in each one. To reconfigure the radiation pattern of the antenna, a PIN‐diode is specifically placed in the discontinuity of the FSS hybrid element for its switching functions. The antenna radiation sector is determined by the off‐state diodes. This design is used to realise a beam‐switching active antenna covering all azimuth angles. The measurement results are in line with the simulation and confirm the proposed configuration of the antenna. The measurement of the proposed design at the operating frequency resulted in a gain of 8.1 dBi. This antenna can be used in the base station of the wireless communication systems.
Acoustic atmospheric tomography using multiple unmanned aerial vehicles
Authors: Finn Anthony , Rogers Kevin
Published: June 2016

A method for tomographically reconstructing atmospheric temperature and wind velocity profiles from measurements of acoustic travel time between two or more unmanned aerial vehicles is presented. The approach avoids the explicit transmission of signals between aircraft, thus lending itself to use in smaller disposable aircraft. As a result, observation of hazardous, remote and hard‐to‐reach environments, otherwise unjustifiable on the basis of cost or risk, becomes possible; and preparation of ground sites is no longer a requirement. The mobility offers the potential for observing dynamically moving atmospheric structures and thus exploitation of dynamic meteorological environments through energy harvesting. An error analysis is provided based on simulations of a daytime convective planetary boundary layer modelled using large eddy simulation. The estimated atmospheric temperature and wind fields, represented as the weighted sum of radial basis functions, are compared to the target data to examine the potential performance envelope of the approach. The accuracy requirements are compared to those of ground‐based acoustic tomography.
Hydrocephalus and Papilledema in Spinal Cord Tumors: A Report of Two Cases
Authors: Marzban Ahmad , Saxena Ankur , Bhattacharyya Dev , Ivanov Marcel
Published: June 2016

Background The association between spinal cord tumors and hydrocephalus is a rarely reported phenomenon. Diagnosis in this group of patients is difficult as they present with findings of an intracranial pathology and the symptoms of a spinal lesion may be absent.

Case Report We report two cases of spinal cord tumors presenting with visual disturbance and findings of increased intracranial pressure.

Discussions Mechanisms describing the relationship between spinal cord tumors and increased intracranial pressure have been explained. Most of the literature reported marked regression of these manifestations after tumor excision.

Conclusions Spinal cord tumors associated with hydrocephalus and papilledema are rare conditions. The diagnosis of these conditions may be difficult or confusing because the symptoms referable to the spinal lesion may be minimal. Meticulous history taking, examination, and investigations are mandatory to diagnose this entity.
Transition from Townsend to radio-frequency homogeneous dielectric barrier discharge in a roll-to-roll configuration
Authors: Bazinette R. , Paillol J. , Massines F.
Published: June 2016

The aim of this paper is to better understand the transition from Townsend to radio-frequency homogeneous dielectric barrier discharge (DBD) at atmospheric pressure. The study is done in an Ar/NH3 Penning mixture for an electrode configuration adapted to roll-to-roll plasma surface treatment. The study was led in a frequency range running from 50 kHz up to 8.3 MHz leading to different DBD modes with a 1 mm gas gap: Glow (GDBD), Townsend (TDBD), and Radio-frequency (RF-DBD). In the frequency range between TDBD and RF-DBD, from 250 kHz to 2.3 MHz, additional discharges are observed outside the inter-electrode gas gap. Because each high voltage electrode are inside a dielectric barrel, these additional discharges occur on the side of the barrel where the gap is larger. They disappear when the RF-DBD mode is attained in the 1 mm inter-electrode gas gap, i.e., for frequencies equal or higher than 3 MHz. Fast imaging and optical emission spectroscopy show that the additional discharges are radio-frequency DBDs while the inter-electrode discharge is a TDBD. The RF-DBD discharge mode is attained when electrons drift becomes low enough compared to the voltage oscillation frequency to limit electron loss at the anode. To check that the additional discharges are due to a larger gas gap and a lower voltage amplitude, the TDBD/RF-DBD transition is investigated as a function of the gas gap and the applied voltage frequency and amplitude. Results show that the increase in the frequency at constant gas gap or in the gas gap at constant frequency allows to obtain RF-DBD instead of TDBD. At low frequency and large gap, the increase in the applied voltage allows RF-DBD/TDBD transition. As a consequence, an electrode configuration allowing different gap values is a solution to successively have different discharge modes with the same applied voltage.
Imaging a multidimensional multichannel potential energy surface: Photodetachment of H−(NH3) and NH4−
Authors: Hu Qichi , Song Hongwei , Johnson Christopher J. , Li Jun , Guo Hua , Continetti Robert E.
Published: June 2016

Probes of the Born-Oppenheimer potential energy surfaces governing polyatomic molecules often rely on spectroscopy for the bound regions or collision experiments in the continuum. A combined spectroscopic and half-collision approach to image nuclear dynamics in a multidimensional and multichannel system is reported here. The Rydberg radical NH4 and the double Rydberg anion NH4− represent a polyatomic system for benchmarking electronic structure and nine-dimensional quantum dynamics calculations. Photodetachment of the H−(NH3) ion-dipole complex and the NH4− DRA probes different regions on the neutral NH4 PES. Photoelectron energy and angular distributions at photon energies of 1.17, 1.60, and 2.33 eV compare well with quantum dynamics. Photoelectron-photofragment coincidence experiments indicate dissociation of the nascent NH4 Rydberg radical occurs to H + NH3 with a peak kinetic energy of 0.13 eV, showing the ground state of NH4 to be unstable, decaying by tunneling-induced dissociation on a time scale beyond the present scope of multidimensional quantum dynamics.
Reflectance characterization of tape-based plasma mirrors
Authors: Shaw B. H. , Steinke S. , van Tilborg J. , Leemans W. P.
Published: June 2016

Specular reflections of relativistic laser pulses from an overdense plasma mirror (PM) were studied experimentally. The pointing stability of the PM and reflectance of the input laser were characterized. The solid material used for the PM was a VHS tape. This study was done for the magnetic and plastic sides of the VHS tape, and for input light of both s and p-polarizations. The laser pulse fluence was varied by changing the focus position relative to the tape surface, which changed the spot size at the tape. The pointing fluctuations of the reflected pulses caused by the PM were ≃1 mrad. A peak reflectance of 82% was obtained from the plastic surface of the VHS tape when focusing s-polarized light 4 mm from the tape surface (the wavefront quality was confirmed to be conserved). An analytic model was developed to understand the physics of the interaction for each tape material and polarization. Fitting of our model parameters to the experimental results allowed an estimate of the key plasma parameters such as plasma expansion velocity, ionization intensity, and fraction of absorbed laser energy.
Comparative study of the Grüneisen parameter for 28 pure fluids
Authors: Mausbach Peter , Köster Andreas , Rutkai Gábor , Thol Monika , Vrabec Jadran
Published: June 2016

The Grüneisen parameter γG is widely used for studying thermal properties of solids at high pressure and also has received increasing interest in different applications of non-ideal fluid dynamics. Because there is a lack of systematic studies of the Grüneisen parameter in the entire fluid region, this study aims to fill this gap. Grüneisen parameter data from molecular modelling and simulation are reported for 28 pure fluids and are compared with results calculated from fundamental equations of state that are based on extensive experimental data sets. We show that the Grüneisen parameter follows a general density-temperature trend and characterize the fluid systems by specifying a span of minimum and maximum values of γG. Exceptions to this trend can be found for water.
A nonlinear structural subgrid-scale closure for compressible MHD. I. Derivation and energy dissipation properties
Authors: Vlaykov Dimitar G. , Grete Philipp , Schmidt Wolfram , Schleicher Dominik R. G.
Published: June 2016

Compressible magnetohydrodynamic (MHD) turbulence is ubiquitous in astrophysical phenomena ranging from the intergalactic to the stellar scales. In studying them, numerical simulations are nearly inescapable, due to the large degree of nonlinearity involved. However, the dynamical ranges of these phenomena are much larger than what is computationally accessible. In large eddy simulations (LESs), the resulting limited resolution effects are addressed explicitly by introducing to the equations of motion additional terms associated with the unresolved, subgrid-scale dynamics. This renders the system unclosed. We derive a set of nonlinear structural closures for the ideal MHD LES equations with particular emphasis on the effects of compressibility. The closures are based on a gradient expansion of the finite-resolution operator [W. K. Yeo (CUP, 1993)] and require no assumptions about the nature of the flow or magnetic field. Thus, the scope of their applicability ranges from the sub- to the hyper-sonic and -Alfvénic regimes. The closures support spectral energy cascades both up and down-scale, as well as direct transfer between kinetic and magnetic resolved and unresolved energy budgets. They implicitly take into account the local geometry, and in particular, the anisotropy of the flow. Their properties are a priori validated in Paper II [P. Grete et al., Phys. Plasmas 23, 062317 (2016)] against alternative closures available in the literature with respect to a wide range of simulation data of homogeneous and isotropic turbulence.
A nonlinear structural subgrid-scale closure for compressible MHD. II. A priori comparison on turbulence simulation data
Authors: Grete Philipp , Vlaykov Dimitar G. , Schmidt Wolfram , Schleicher Dominik R. G.
Published: June 2016

Even though compressible plasma turbulence is encountered in many astrophysical phenomena, its effect is often not well understood. Furthermore, direct numerical simulations are typically not able to reach the extreme parameters of these processes. For this reason, large-eddy simulations (LES), which only simulate large and intermediate scales directly, are employed. The smallest, unresolved scales and the interactions between small and large scales are introduced by means of a subgrid-scale (SGS) model. We propose and verify a new set of nonlinear SGS closures for future application as an SGS model in LES of compressible magnetohydrodynamics. We use 15 simulations (without explicit SGS model) of forced, isotropic, homogeneous turbulence with varying sonic Mach number Ms=0.2–20 as reference data for the most extensive a priori tests performed so far in literature. In these tests, we explicitly filter the reference data and compare the performance of the new closures against the most widely tested closures. These include eddy-viscosity and scale-similarity type closures with different normalizations. Performance indicators are correlations with the turbulent energy and cross-helicity flux, the average SGS dissipation, the topological structure and the ability to reproduce the correct magnitude and the direction of the SGS vectors. We find that only the new nonlinear closures exhibit consistently high correlations (median value > 0.8) with the data over the entire parameter space and outperform the other closures in all tests. Moreover, we show that these results are independent of resolution and chosen filter scale. Additionally, the new closures are effectively coefficient-free with a deviation of less than 20%.
Transport properties and Stokes-Einstein relation in Al-rich liquid alloys
Authors: Jakse N. , Pasturel A.
Published: June 2016

We use ab initio molecular dynamics simulations to study the transport properties and the validity of the Stokes-Einstein relation in Al-rich liquid alloys with Ni, Cu, and Zn as alloying elements. First, we show that the composition and temperature dependence of their transport properties present different behaviors, which can be related to their local structural ordering. Then, we evidence that the competition between the local icosahedral ordering and the local chemical ordering may cause the breakdown of the Stokes–Einstein relation even in the liquid phase. We demonstrate that this breakdown can be captured by entropy-scaling relationships developed by Rosenfeld and using the two-body excess entropy. Our findings provide a unique framework to study the relation between structure, thermodynamics, and dynamics in metallic melts and pave the way towards the explanation of various complex transport properties in metallic melts.
Atomistically derived cohesive zone model of intergranular fracture in polycrystalline graphene
Authors: Guin Laurent , Raphanel Jean L. , Kysar Jeffrey W.
Published: June 2016

Pristine single crystal graphene is the strongest known two-dimensional material, and its nonlinear anisotropic mechanical properties are well understood from the atomic length scale up to a continuum description. However, experiments indicate that grain boundaries in the polycrystalline form reduce the mechanical behavior of polycrystalline graphene. Herein, we perform atomistic-scale molecular dynamics simulations of the deformation and fracture of graphene grain boundaries and express the results as continuum cohesive zone models (CZMs) that embed notions of the grain boundary ultimate strength and fracture toughness. To facilitate energy balance, we employ a new methodology that simulates a quasi-static controlled crack propagation which renders the kinetic energy contribution to the total energy negligible. We verify good agreement between Griffith's critical energy release rate and the work of separation of the CZM, and we note that the energy of crack edges and fracture toughness differs by about 35%, which is attributed to the phenomenon of bond trapping. This justifies the implementation of the CZM within the context of the finite element method (FEM). To enhance computational efficiency in the FEM implementation, we discuss the use of scaled traction-separation laws (TSLs) for larger element sizes. As a final result, we have established that the failure characteristics of pristine graphene and high tilt angle bicrystals differ by less than 10%. This result suggests that one could use a unique or a few typical TSLs as a good approximation for the CZMs associated with the mechanical simulations of the polycrystalline graphene.
Towards a wearable near infrared spectroscopic probe for monitoring concentrations of multiple chromophores in biological tissue in vivo
Authors: Chitnis Danial , Airantzis Dimitrios , Highton David , Williams Rhys , Phan Phong , Giagka Vasiliki , Powell Samuel , Cooper Robert J. , Tachtsidis Ilias , Smith Martin , Elwell Clare E. , Hebden Jeremy C. , Everdell Nicholas
Published: June 2016

The first wearable multi-wavelength technology for functional near-infrared spectroscopy has been developed, based on a custom-built 8-wavelength light emitting diode (LED) source. A lightweight fibreless probe is designed to monitor changes in the concentrations of multiple absorbers (chromophores) in biological tissue, the most dominant of which at near-infrared wavelengths are oxyhemoglobin and deoxyhemoglobin. The use of multiple wavelengths enables signals due to the less dominant chromophores to be more easily distinguished from those due to hemoglobin and thus provides more complete and accurate information about tissue oxygenation, hemodynamics, and metabolism. The spectroscopic probe employs four photodiode detectors coupled to a four-channel charge-to-digital converter which includes a charge integration amplifier and an analogue-to-digital converter (ADC). Use of two parallel charge integrators per detector enables one to accumulate charge while the other is being read out by the ADC, thus facilitating continuous operation without dead time. The detector system has a dynamic range of about 80 dB. The customized source consists of eight LED dies attached to a 2 mm × 2 mm substrate and encapsulated in UV-cured epoxy resin. Switching between dies is performed every 20 ms, synchronized to the detector integration period to within 100 ns. The spectroscopic probe has been designed to be fully compatible with simultaneous electroencephalography measurements. Results are presented from measurements on a phantom and a functional brain activation study on an adult volunteer, and the performance of the spectroscopic probe is shown to be very similar to that of a benchtop broadband spectroscopy system. The multi-wavelength capabilities and portability of this spectroscopic probe will create significant opportunities for in vivo studies in a range of clinical and life science applications.
1 Hz linewidth Ti:sapphire laser as local oscillator for 40Ca+ optical clocks
Authors: Bian Wu , Huang Yao , Guan Hua , Liu Peiliang , Ma Longsheng , Gao Kelin
Published: June 2016

A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10−15 frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled 40Ca+ ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10−14) is observed. This laser is also used as the local oscillator for the comparison experiment of two 40Ca+ ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results.
Post-Hartree-Fock studies of the He/Mg(0001) interaction: Anti-corrugation, screening, and pairwise additivity
Authors: de Lara-Castells María Pilar , Fernández-Perea Ricardo , Madzharova Fani , Voloshina Elena
Published: June 2016

The adsorption of noble gases on metallic surfaces represents a paradigmatic case of van-der-Waals (vdW) interaction due to the role of screening effects on the corrugation of the interaction potential [J. L. F. Da Silva et al., Phys. Rev. Lett. 90, 066104 (2003)]. The extremely small adsorption energy of He atoms on the Mg(0001) surface (below 3 meV) and the delocalized nature and mobility of the surface electrons make the He/Mg(0001) system particularly challenging, even for state-of-the-art vdW-corrected density functional-based (vdW-DFT) approaches [M. P. de Lara-Castells et al., J. Chem. Phys. 143, 194701 (2015)]. In this work, we meet this challenge by applying two different procedures. First, the dispersion-corrected second-order Möller-Plesset perturbation theory (MP2C) approach is adopted, using bare metal clusters of increasing size. Second, the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)] is applied at coupled cluster singles and doubles and perturbative triples level, using embedded cluster models of the metal surface. Both approaches provide clear evidences of the anti-corrugation of the interaction potential: the He atom prefers on-top sites, instead of the expected hollow sites. This is interpreted as a signature of the screening of the He atom by the metal for the on-top configuration. The strong screening in the metal is clearly reflected in the relative contribution of successively deeper surface layers to the main dispersion contribution. Aimed to assist future dynamical simulations, a pairwise potential model for the He/surface interaction as a sum of effective He–Mg pair potentials is also presented, as an improvement of the approximation using isolated He–Mg pairs.
Modeling surface motion effects in N2 dissociation on W(110): Ab initio molecular dynamics calculations and generalized Langevin oscillator model
Authors: Nattino Francesco , Galparsoro Oihana , Costanzo Francesca , Díez Muiño Ricardo , Alducin Maite , Kroes Geert-Jan
Published: June 2016

Accurately modeling surface temperature and surface motion effects is necessary to study molecule-surface reactions in which the energy dissipation to surface phonons can largely affect the observables of interest. We present here a critical comparison of two methods that allow to model such effects, namely, the ab initio molecular dynamics (AIMD) method and the generalized Langevin oscillator (GLO) model, using the dissociation of N2 on W(110) as a benchmark. AIMD is highly accurate as the surface atoms are explicitly part of the dynamics, but this advantage comes with a large computational cost. The GLO model is much more computationally convenient, but accounts for lattice motion effects in a very approximate way. Results show that, despite its simplicity, the GLO model is able to capture the physics of the system to a large extent, returning dissociation probabilities which are in better agreement with AIMD than static-surface results. Furthermore, the GLO model and the AIMD method predict very similar energy transfer to the lattice degrees of freedom in the non-reactive events, and similar dissociation dynamics.
Hamiltonian analysis for linearly acceleration-dependent Lagrangians
Authors: Cruz Miguel , Gómez-Cortés Rosario , Molgado Alberto , Rojas Efraín
Published: June 2016

We study the constrained Ostrogradski-Hamilton framework for the equations of motion provided by mechanical systems described by second-order derivative actions with a linear dependence in the accelerations. We stress out the peculiar features provided by the surface terms arising for this type of theories and we discuss some important properties for this kind of actions in order to pave the way for the construction of a well defined quantum counterpart by means of canonical methods. In particular, we analyse in detail the constraint structure for these theories and its relation to the inherent conserved quantities where the associated energies together with a Noether charge may be identified. The constraint structure is fully analyzed without the introduction of auxiliary variables, as proposed in recent works involving higher order Lagrangians. Finally, we also provide some examples where our approach is explicitly applied and emphasize the way in which our original arrangement results in propitious for the Hamiltonian formulation of covariant field theories.
Exploration of magnetic perturbation effects on advanced divertor configurations in NSTX-U
Authors: Frerichs H. , Schmitz O. , Waters I. , Canal G. P. , Evans T. E. , Feng Y. , Soukhanovskii V. A.
Published: June 2016

The control of divertor heat loads—both steady state and transient—remains a key challenge for the successful operation of ITER and FNSF. Magnetic perturbations provide a promising technique to control ELMs (Edge Localized Modes) (transients), but understanding their detailed impact is difficult due to their symmetry breaking nature. One approach for reducing steady state heat loads is so called “advanced divertors” which aim at optimizing the magnetic field configuration: the snowflake and the (super-)X-divertor. It is likely that both concepts—magnetic perturbations and advanced divertors—will have to work together, and we explore their interaction based on the NSTX-U setup. An overview of different divertor configurations under the impact of magnetic perturbations is presented, and the resulting impact on plasma edge transport is investigated with the EMC3-EIRENE code. Variations in size of the magnetic footprint of the perturbed separatrix are found, which are related to the level of flux expansion on the divertor target. Non-axisymmetric peaking of the heat flux related to the perturbed separatrix is found at the outer strike point, but only in locations where flux expansion is not too large.
Study on dynamics of the influence exerted by plasma on gas flow field in non-thermal atmospheric pressure plasma jet
Authors: Qaisrani M. Hasnain , Xian Yubin , Li Congyun , Pei Xuekai , Ghasemi Maede , Lu Xinpei
Published: June 2016

In this paper, first, steady state of the plasma jet at different operating conditions is investigated through Schlieren photography with and without applying shielding gas. Second, the dynamic process for the plasma impacting on the gas flow field is studied. When the discharge is ignited, reduction in laminar flow occurs. However, when the gas flow rate is too low or too high, this phenomenon is not obvious. What is more, both frequency and voltage have significant impact on the effect of plasma on the gas flow, but the former is more significant. Shielding gas provides a curtain for plasma to propagate further. High speed camera along with Schlieren photography is utilized to study the impact of plasma on the gas flow when plasma is switched on and off. The transition of the gas flow from laminar to turbulent or vice versa happens right after the turbulent front. It is concluded that appearance and propagation of turbulence front is responsible for the transition of the flow state.
Topological insulator homojunctions including magnetic layers: The example of n-p type (n-QLs Bi2Se3/Mn-Bi2Se3) heterostructures
Authors: Vališka M. , Warmuth J. , Michiardi M. , Vondráček M. , Ngankeu A. S. , Holý V. , Sechovský V. , Springholz G. , Bianchi M. , Wiebe J. , Hofmann P. , Honolka J.
Published: June 2016

Homojunctions between Bi2Se3 and its Mn-doped phase are investigated as a sample geometry to study the influence of spin degrees of freedom on topological insulator properties. n quintuple layers of Bi2Se3 are grown on top of Mn-doped Bi2Se3 by molecular beam epitaxy for 0≤n≤30 QLs, allowing to unhamperedly monitor the development of electronic and topological properties by surface sensitive techniques like angle resolved photoemission spectroscopy. With increasing n, a Mn-induced gap at the Dirac point is gradually filled in an “hourglass” fashion to reestablish a topological surface state at n∼9 QLs. Our results suggest a competition of upward and downward band bending effects due to the presence of an n-p type interface, which can be used to tailor topological and quantum well states independently.
Extreme ultraviolet radiation emitted by helium microwave driven plasmas
Authors: Espinho S. , Felizardo E. , Tatarova E. , Alves L. L.
Published: June 2016

The extreme ultraviolet radiation emitted by helium microwave-driven (2.45 GHz) plasmas operating at low-pressure conditions was investigated. Novel data regarding emitted spectral lines of excited helium atoms and ions in the 20–33 nm wavelength range and their intensity behavior with variation of discharge operational conditions are presented. The intensity of all the spectral emissions was found to strongly increase with the microwave power delivered to the plasma. Furthermore, the intensity of the ionic spectral emissions decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar.
The residual zonal flows in anisotropic tokamak plasmas
Authors: Ren Haijun
Published: June 2016

The gyro-kinetic equation is analytically solved based on the anisotropic two-temperature distribution, in which the ions' parallel temperature is a flux function while the perpendicular temperature depends on the poloidal angle. The residual level of collisionless zonal flows (ZFs) is derived and calculated in the large aspect circular limit. Our result shows that the anisotropy plays a remarkable role in determining the residual value of ZFs. Even weak anisotropy can significantly change the residual level.
A nanoemitter based on a superconducting material
Authors: Hou Jin-Long , Chang Wei-Tse , Shih Chih-Chiang , Yu Yu-Fong , Fu Tsu-Yi , Hwang Ing-Shouh
Published: June 2016

The coherence of an electron beam is crucial for the performance of electron microscopy, coherent diffractive imaging, holography, and many other advanced instrumentation methods that rely on the phase coherence of electron waves. Here we present a reliable method for preparing a niobium nanoemitter, which is thermally and chemically stable. The tip apex is a (100) facet with a lateral dimension of ∼1 nm, surrounded by four (310) facets. Adsorption of one monolayer of noble gas, particularly Xe, onto the nanoemitter greatly enhances the emission current and current stability. This electron source will probably possess both spatial and temporal coherence if the emitter is cooled below the superconducting temperature.
Disentangling nonradiative recombination processes in Ge micro-crystals on Si substrates
Authors: Pezzoli Fabio , Giorgioni Anna , Gallacher Kevin , Isa Fabio , Biagioni Paolo , Millar Ross W. , Gatti Eleonora , Grilli Emanuele , Bonera Emiliano , Isella Giovanni , Paul Douglas J. , Miglio Leo
Published: June 2016

We address nonradiative recombination pathways by leveraging surface passivation and dislocation management in μm-scale arrays of Ge crystals grown on deeply patterned Si substrates. The time decay photoluminescence (PL) at cryogenic temperatures discloses carrier lifetimes approaching 45 ns in band-gap engineered Ge micro-crystals. This investigation provides compelling information about the competitive interplay between the radiative band-edge transitions and the trapping of carriers by dislocations and free surfaces. Furthermore, an in-depth analysis of the temperature dependence of the PL, combined with capacitance data and finite difference time domain modeling, demonstrates the effectiveness of GeO2 in passivating the surface of Ge and thus in enhancing the room temperature PL emission.
A light-stimulated synaptic transistor with synaptic plasticity and memory functions based on InGaZnOx–Al2O3 thin film structure
Authors: Li H. K. , Chen T. P. , Liu P. , Hu S. G. , Liu Y. , Zhang Q. , Lee P. S.
Published: June 2016

In this work, a synaptic transistor based on the indium gallium zinc oxide (IGZO)–aluminum oxide (Al2O3) thin film structure, which uses ultraviolet (UV) light pulses as the pre-synaptic stimulus, has been demonstrated. The synaptic transistor exhibits the behavior of synaptic plasticity like the paired-pulse facilitation. In addition, it also shows the brain's memory behaviors including the transition from short-term memory to long-term memory and the Ebbinghaus forgetting curve. The synapse-like behavior and memory behaviors of the transistor are due to the trapping and detrapping processes of the holes, which are generated by the UV pulses, at the IGZO/Al2O3 interface and/or in the Al2O3 layer.
Effects of surface finish and mechanical training on Ni-Ti sheets for elastocaloric cooling
Authors: Engelbrecht Kurt , Tušek Jaka , Sanna Simone , Eriksen Dan , Mishin Oleg V. , Bahl Christian R. H. , Pryds Nini
Published: June 2016

Elastocaloric cooling has emerged as a promising alternative to vapor compression in recent years. Although the technology has the potential to be more efficient than current technologies, there are many technical challenges that must be overcome to realize devices with high performance and acceptable durability. We study the effects of surface finish and training techniques on dog bone shaped polycrystalline samples of NiTi. The fatigue life of several samples with four different surface finishes was measured and it was shown that a smooth surface, especially at the edges, greatly improved fatigue life. The effects of training both on the structure of the materials and the thermal response to an applied strain was studied. The load profile for the first few cycles was shown to change the thermal response to strain, the structure of the material at failure while the final structure of the material was weakly influenced by the surface finish.
Genetic and morphological evidence for a new mountain-living freshwater crab species (Decapoda : Potamonautidae : Potamonautes) from the Western Cape province of South Africa
Authors: Wood Louisa E. , Daniels Savel R.
Published: June 2016

Recent studies in southern Africa have revealed a wealth of novel freshwater crab species in high mountainous regions. In the present study, phylogeographic affinities between two sister mountain-living freshwater crab species (Potamonautes brincki and P. parvicorpus) were examined for novel lineages. Seventy-six crab specimens were collected throughout the Western Cape Province of South Africa and sequenced for the COI locus. Evolutionary relationships were analysed using Bayesian inference, maximum likelihood and maximum parsimony, a haplotype network and analyses of molecular variance (AMOVA). Results revealed three divergent clades. Clade A comprised specimens of P. brincki restricted to the Hottentots Holland; sister to which was Clade B from the Overberg, while Clade C comprised specimens of P. parvicorpus from the Cape Peninsula and adjacent interior. Haplotype networks and AMOVA provide evidence for the absence of gene flow whilst morphology of the male gonopods and the mandibular palp revealed subtle but consistent differences between the three clades. Since Clades A and C represent two described species, P. brincki and P. parvicorpus, respectively, Clade B is herein described as a new species, P. tuerkayi, sp. nov. These results highlight the importance of continued sampling of mountain habitats to document aquatic invertebrate diversity.
First report of Aphanizomenon favaloroi occurrence in Europe associated with saxitoxins and a massive fish kill in Lake Vistonis, Greece
Authors: Moustaka-Gouni Maria , Hiskia Anastasia , Genitsaris Savvas , Katsiapi Matina , Manolidi Korina , Zervou Sevasti-Kiriaki , Christophoridis Christophoros , Triantis Theodoros M. , Kaloudis Triantafyllos , Orfanidis Sotiris
Published: June 2016

The cyanobacterium Aphanizomenon favaloroi was identified for the first time in Europe in the Mediterranean brackish Lake Vistonis during July–August 2014. It formed a dense bloom (from 16×106 to 81×106 trichomes L–1), causing a brown colouration of the lake water. When A. favaloroi formed 100% of the total phytoplankton biomass (44mg L–1), saxitoxins (saxitoxin and neo-saxitoxin) were detected in the lake seston (42 and 17μg g–1 phytoplankton dry weight respectively), which was screened for saxitoxins, cylindrospermopsin, anatoxin-a, microcystins and nodularin. A massive fish kill coincided with the A. favaloroi bloom. This new saxitoxin-producing species of cyanobacteria, with traits for successful dispersal, may pose a health risk to animals and humans and cause adverse effects on water quality and water services because of its expansion potential.
A face-selective ventral occipito-temporal map of the human brain with intracerebral potentials
Authors: Jonas Jacques , Jacques Corentin , Liu-Shuang Joan , Brissart Hélène , Colnat-Coulbois Sophie , Maillard Louis , Rossion Bruno
Published: June 2016

Significance

Understanding the neural basis of face perception, arguably the most important visual function for human social ecology, is of the utmost importance. With an original fast periodic visual stimulation approach, we provide a comprehensive quantification of selective brain responses to faces throughout the ventral visual stream with direct recordings in the gray matter. Selective responses to faces are distributed in the whole ventral occipito-temporal cortex, with a right hemispheric and regional specialization supporting two decades of indirect recordings of human brain activity in neuroimaging. We also disclose three distinct face-selective regions in the anterior temporal lobe, an undersampled region in neuroimaging, and reveal exclusive responses to faces at the neural population level in these regions.
Tautomerization-dependent recognition and excision of oxidation damage in base-excision DNA repair
Authors: Zhu Chenxu , Lu Lining , Zhang Jun , Yue Zongwei , Song Jinghui , Zong Shuai , Liu Menghao , Stovicek Olivia , Gao Yi Qin , Yi Chengqi
Published: June 2016

Significance

Oxidative DNA damage can be cytotoxic or mutagenic to cells. NEIL1 (Nei-like 1) is a DNA repair glycosylase guarding the mammalian genome against various oxidized DNA bases; yet how NEIL1 recognizes and catalyzes the removal of its substrates remains poorly understood. Here we integrate crystal structures of a NEIL1/double-stranded DNA complex, computational simulations, and biochemical analyses and show that NEIL1 promotes tautomerization of thymine glycol—a cognate substrate—for efficient substrate recognition and excision. Such tautomerism-dependent substrate recognition and catalysis is, to the best of our knowledge, reported for the first time in an enzyme-catalyzed reaction.
Biomechanics of red blood cells in human spleen and consequences for physiology and disease
Authors: Pivkin Igor V. , Peng Zhangli , Karniadakis George E. , Buffet Pierre A. , Dao Ming , Suresh Subra
Published: June 2016

Significance

The 3D opening of the interendothelial slit in human spleen creates a physical fitness test for red blood cells (RBCs) and clears them from circulation if their geometry and deformability are altered. We present a unique computational framework for the development of prognostic markers for diseases that alter RBC physical characteristics and identify quantitative limits for splenic slit clearance. Our work shows how the splenic slit determines distributions of size and shape of healthy RBCs. Our work lays the groundwork for systematic reconstruction of RBC navigation in the human spleen with consequences for a variety of acute and chronic medical conditions associated with hereditary alterations of RBCs, infectious diseases, and cancers.
Human antibody responses after dengue virus infection are highly cross-reactive to Zika virus
Authors: Priyamvada Lalita , Quicke Kendra M. , Hudson William H. , Onlamoon Nattawat , Sewatanon Jaturong , Edupuganti Srilatha , Pattanapanyasat Kovit , Chokephaibulkit Kulkanya , Mulligan Mark J. , Wilson Patrick C. , Ahmed Rafi , Suthar Mehul S. , Wrammert Jens
Published: June 2016

Significance

In this study, we address the issue of cross-reactivity between dengue virus (DENV) and Zika virus (ZIKV) by testing sera and plasmablast-derived monoclonal antibodies from dengue patients against ZIKV. We show that both acute and convalescent dengue sera potently bind and neutralize ZIKV and that this cross-reactivity is also evident at the monoclonal level. We also demonstrate in vitro antibody-dependent enhancement of ZIKV infection in the presence of dengue-induced antibodies. Our findings strongly suggest that preexisting dengue antibodies may modulate immune responses to ZIKV infection. These data are timely and highly relevant from a public health standpoint given that a majority of regions currently experiencing Zika virus epidemics are endemic for dengue.