bluuebunny/crossref_metadata_2025 huggingface dataset:
CAD-based Monte Carlo Program for Integrated Simulation of Nuclear System SuperMC
Authors: Wu Yican , Song Jing , Zheng Huaqing , Sun Guangyao , Hao Lijuan , Long Pengcheng , Hu Liqin ,   FDS Team
Published: June 2014

Monte Carlo (MC) method has distinct advantages to simulate complicated nuclear systems and is envisioned as routine method for nuclear design and analysis in the future. High fidelity simulation with MC method coupled with multi-physical phenomenon simulation has significant impact on safety, economy and sustainability of nuclear systems. However, great challenges to current MC methods and codes prevent its application in real engineering project. SuperMC is a CAD-based Monte Carlo program for integrated simulation of nuclear system developed by FDS Team, China, making use of hybrid MC-deterministic method and advanced computer technologies. The design aim, architecture and main methodology of SuperMC were presented in this paper. SuperMC2.1, the latest version for neutron, photon and coupled neutron and photon transport calculation, has been developed and validated by using a series of benchmarking cases such as the fusion reactor ITER model and the fast reactor BN-600 model. SuperMC is still in its evolution process toward a general and routine tool for nuclear system.
TRIPOLI-4®, CEA, EDF and AREVA Reference Monte Carlo Code
Authors:   TRIPOLI-4® Project Team, Brun E. , Damian F. , Diop C.M. , Dumonteil E. , Hugot F.X. , Jouanne C. , Lee Y.K. , Malvagi F. , Mazzolo A. , Petit O. , Trama J.C. , Visonneau T. , Zoia A.
Published: June 2014

This paper presents an overview of TRIPOLI-4®, the fourth generation of the 3D continuous-energy Monte Carlo code developed by the Service d’Etudes des Réacteurs et de Mathématiques Appliquées (SERMA) at CEA Saclay. The paper surveys the generic features: programming language, parallel operation, tracked particles, nuclear data, geometry, simulation modes, standard variance reduction techniques, sources, tracking and collision algorithms, tallies, sensitivity studies. Moreover, specific and recent features are also detailed: Doppler broadening of the elastic scattering kernel, neutron and photon material irradiation, advanced variance reduction techniques, Green’s functions, cycle correlation correction, nuclear data management and depletion capabilities. The productivity tools (T4G, SALOME TRIPOLI, T4RootTools), the Verification & Validation process and the distribution and licensing policy are finally presented.
Stationary Vortex Arrays
Authors: Lubkin Gloria B.
Published: June 2014

Take a good look at these photographs; eventually they will probably be in many textbooks. These photographs represent visual evidence for macroscopic quantization in rotating supertluid helium and are the latest in a series of experiments by Richard Packard and his collaborators at the University of California, Berkeley. E. J. Yarmchuk, M. J. V. Gordon and Packard recently published these pictures in Phys. Rev. Lett. 43, 214 (1979). These patterns display the model structure of the stationary states of a single macroscopic wave function describing superfluidity.
Separation of interlayer resistance in multilayer MoS2 field-effect transistors
Authors: Na Junhong , Shin Minju , Joo Min-Kyu , Huh Junghwan , Jeong Kim Yun , Jong Choi Hyung , Hyung Shim Joon , Kim Gyu-Tae
Published: June 2014

We extracted the interlayer resistance between two layers in multilayer molybdenum disulfide (MoS2) field-effect transistors by confirming that contact resistances (Rcontact) measured using the four-probe measurements were similar, within ∼30%, to source/drain series resistances (Rsd) measured using the two-probe measurements. Rcontact values obtained from gated four-probe measurements exhibited gate voltage dependency. In the two-probe measurements, the Y-function method was applied to obtain the Rsd values. By comparing those two Rcontact (∼9.5 kΩ) and Rsd (∼12.3 kΩ) values in strong accumulation regime, we found the rationality that those two values had nearly the same properties, i.e., the Schottky barrier resistances and interlayer resistances. The Rsd values of devices with two-probe source/drain electrodes exhibited thickness dependency due to interlayer resistance changes. The interlayer resistance between two layers was also obtained as ∼2.0 Ω mm.
Structural and optical properties of (Ag,Cu)(In,Ga)Se2 polycrystalline thin film alloys
Authors: Boyle J. H. , McCandless B. E. , Shafarman W. N. , Birkmire R. W.
Published: June 2014

The structural and optical properties of pentenary alloy (Ag,Cu)(In,Ga)Se2 polycrystalline thin films were characterized over the entire compositional range at a fixed (Cu + Ag)/(In + Ga) ratio. Films deposited at 550 °C on bare and molybdenum coated soda-lime glass by elemental co-evaporation in a single-stage process with constant incident fluxes exhibit single phase chalcopyrite structure, corresponding to 122 spacegroup (I-42d) over the entire compositional space. Unit cell refinement of the diffraction patterns show that increasing Ag substitution for Cu, the refined ao lattice constant, (Ag,Cu)-Se bond length, and anion displacement increase in accordance with the theoretical model proposed by Jaffe, Wei, and Zunger. However, the refined co lattice constant and (In,Ga)-Se bond length deviated from theoretical expectations for films with mid-range Ag and Ga compositions and are attributed to influences from crystallographic bond chain ordering or cation electronegativity. The optical band gap, derived from transmission and reflection measurements, widened with increasing Ag and Ga content, due to influences from anion displacement and cation electronegativity, as expected from theoretical considerations for pseudo-binary chalcopyrite compounds.
Adsorption of probe molecules in pillared interlayered clays: Experiment and computer simulation
Authors: Gallardo A. , Guil J. M. , Lomba E. , Almarza N. G. , Khatib S. J. , Cabrillo C. , Sanz A. , Pires J.
Published: June 2014

In this paper we investigate the adsorption of various probe molecules in order to characterize the porous structure of a series of pillared interlayered clays (PILC). To that aim, volumetric and microcalorimetric adsorption experiments were performed on various Zr PILC samples using nitrogen, toluene, and mesitylene as probe molecules. For one of the samples, neutron scattering experiments were also performed using toluene as adsorbate. Various structural models are proposed and tested by means of a comprehensive computer simulation study, using both geometric and percolation analysis in combination with Grand Canonical Monte Carlo simulations in order to model the volumetric and microcalorimetric isotherms. On the basis of this analysis, we propose a series of structural models that aim at accounting for the adsorption experimental behavior, and make possible a microscopic interpretation of the role played by the different interactions and steric effects in the adsorption processes in these rather complex disordered microporous systems.
The thermal conductivity of clustered nanocolloids
Authors: Lotfizadeh Saba , Desai Tapan , Matsoukas Themis
Published: June 2014

We quantify the effect of clustering on the thermal conductivity of colloidal dispersions using silane-treated silica, a system engineered to exhibit reversible clustering under well-controlled conditions. We show that the thermal conductivity increases monotonically with cluster size and spans the entire range between the two limits of Maxwell's theory. The results, corroborated by numerical simulation, demonstrate that large increases of the thermal conductivity of colloidal dispersions are possible, yet fully within the predictions of classical theory.
Site specific isolated nanostructure array formation on a large area by broad ion beam without any mask and resist
Authors: Karmakar Prasanta , Satpati Biswarup
Published: June 2014

We report the formation of isolated nanostructure arrays on a large area via broad ion beam implantation without the aid of any mask or resist. Desired ions have been implanted at specific locations of the prefabricated silicon ripple or triangular structures by exploiting the variation of local ion impact angles. We have shown that the implantation of Fe ions on an O+ ions induced pre fabricated triangular shaped patterned Si surface results in a self-organized periodic array of striped magnetic nanostructures having several micron length and about 50 nm width arranged with a spacial separation of ∼200 nm. The morphology, composition, crystalline structure, and magnetic property of these nanopatterns have been analyzed using high-resolution cross-sectional transmission electron microscopy and atomic force microscopy. A geometrical model has been proposed to explain the fundamental features of such ion-induced nanopattern structures.
Dipole polarizability of alkali-metal (Na, K, Rb)–alkaline-earth-metal (Ca, Sr) polar molecules: Prospects for alignment
Authors: Gopakumar Geetha , Abe Minori , Hada Masahiko , Kajita Masatoshi
Published: June 2014

Electronic open-shell ground-state properties of selected alkali-metal–alkaline-earth-metal polar molecules are investigated. We determine potential energy curves of the 2Σ+ ground state at the coupled-cluster singles and doubles with partial triples (CCSD(T)) level of electron correlation. Calculated spectroscopic constants for the isotopes (23Na, 39K, 85Rb)–(40Ca, 88Sr) are compared with available theoretical and experimental results. The variation of the permanent dipole moment (PDM), average dipole polarizability, and polarizability anisotropy with internuclear distance is determined using finite-field perturbation theory at the CCSD(T) level. Owing to moderate PDM (KCa: 1.67 D, RbCa: 1.75 D, KSr: 1.27 D, RbSr: 1.41 D) and large polarizability anisotropy (KCa: 566 a.u., RbCa: 604 a.u., KSr: 574 a.u., RbSr: 615 a.u.), KCa, RbCa, KSr, and RbSr are potential candidates for alignment and orientation in combined intense laser and external static electric fields.
Hydrodynamic behavior in the outer shear layer of partly obstructed open channels
Authors: Ben Meftah Mouldi , De Serio Francesca , Mossa Michele
Published: June 2014

Despite the many studies on flow in partly obstructed open channels, this issue remains of fundamental importance in order to better understand the interaction between flow behavior and the canopy structure. In the first part of this study we suggest a new theoretical approach able to model the flow pattern within the shear layer in the unobstructed domain, adjacent to the canopy area. Differently from previous studies, the new analytical solution of flow momentum equations takes into account the transversal velocity component of the flow, which is modelled as a linear function of the streamwise velocity. The proposed theoretical model is validated by different experiments carried out on a physical model of a very large rectangular channel by the research group of the Department of Civil, Environmental, Building Engineering and Chemistry of the Technical University of Bari. An array of vertical, rigid, and circular steel cylinders was partially mounted on the bottom in the central part of the flume, leaving two lateral areas of free flow circulation near the walls. The three-dimensional flow velocity components were measured using a 3D Acoustic Doppler Velocimeter. A comparison of the measured and predicted data of the present study with those obtained in other previous studies, carried out with different canopy density, show a non-dependence of this analytical solution on the array density and the Reynolds number. In the second part of the paper, detailed observations of turbulent intensities and spanwise Reynolds stresses in the unobstructed flow are analyzed and discussed. Differently from some earlier studies, it was observed that the peak of the turbulence intensity and that of the spanwise Reynolds stress are significantly shifted toward the center of the shear layer.
A bubble detection system for propellant filling pipeline
Authors: Wen Wen , Zong Guanghua , Bi Shusheng
Published: June 2014

This paper proposes a bubble detection system based on the ultrasound transmission method, mainly for probing high-speed bubbles in the satellite propellant filling pipeline. First, three common ultrasonic detection methods are compared and the ultrasound transmission method is used in this paper. Then, the ultrasound beam in a vertical pipe is investigated, suggesting that the width of the beam used for detection is usually smaller than the internal diameter of the pipe, which means that when bubbles move close to the pipe wall, they may escape from being detected. A special device is designed to solve this problem. It can generate the spiral flow to force all the bubbles to ascend along the central line of the pipe. In the end, experiments are implemented to evaluate the performance of this system. Bubbles of five different sizes are generated and detected. Experiment results show that the sizes and quantity of bubbles can be estimated by this system. Also, the bubbles of different radii can be distinguished from each other. The numerical relationship between the ultrasound attenuation and the bubble radius is acquired and it can be utilized for estimating the unknown bubble size and measuring the total bubble volume.
Ab initio calculation of ICD widths in photoexcited HeNe
Authors: Jabbari G. , Klaiman S. , Chiang Y.-C. , Trinter F. , Jahnke T. , Gokhberg K.
Published: June 2014

Excitation of HeNe by synchrotron light just below the frequency of the 1s → 3p transition of isolated He has been recently shown to be followed by resonant interatomic Coulombic decay (ICD). The vibrationally resolved widths of the ICD states were extracted with high precision from the photoion spectra. In this paper, we report the results of ab initio calculations of these widths. We show that interaction between electronic states at about the equilibrium distance of HeNe makes dark states of He accessible for the photoexcitation and subsequent electronic decay. Moreover, the values of the calculated widths are shown to be strongly sensitive to the presence of the non-adiabatic coupling between the electronic states participating in the decay. Therefore, only by considering the complete manifold of interacting decaying electronic states a good agreement between the measured and computed ICD widths can be achieved.
Pressure tuning of laser diodes in the near-infrared up to 1850 nm: Operational characteristics and reliability studies
Authors: Bercha Artem , Dybala Filip , Piechal Bernard , Ivonyak Yurii , Klimczak Mariusz , Trzeciakowski Witold A.
Published: June 2014

Wavelength tuning of infrared laser diodes in the high-hydrostatic pressure setup is demonstrated and its reliability is discussed in detail. Major reliability issues concern the photochemical reactions on the laser facet and the presence of strong absorption bands above 1650 nm in typical pressure liquids that do not undergo phase transitions up to 20 kbar. Despite these difficulties spectrally wide-range pressure tuning can be achieved with sufficient reliability for spectroscopic applications.
A mean-field monomer-dimer model with attractive interaction: Exact solution and rigorous results
Authors: Alberici D. , Contucci P. , Mingione E.
Published: June 2014

A mean-field monomer-dimer model which includes an attractive interaction among both monomers and dimers is introduced and its exact solution rigorously derived. The Heilmann-Lieb method for the pure hard-core interacting case is used to compute upper and lower bounds for the pressure. The bounds are shown to coincide in the thermodynamic limit for a suitable choice of the monomer density m. The computation of the monomer density is achieved by solving a consistency equation in the phase space (h, J), where h tunes the monomer potential and J the attractive potential. The critical point and exponents are computed and show that the model is in the mean-field ferromagnetic universality class.
Observation of negative differential resistance and electrical bi-stability in chemically synthesized ZnO nanorods
Authors: Roy Nandini , Chowdhury Avijit , Roy Asim
Published: June 2014

Zinc oxide nanorods/p-Si heterostructures have been fabricated by depositing the chemically synthesized ZnO nanorods on p-type silicon substrate. Heterostructure shows electrical bi-stability and negative differential resistance (NDR) only at the beginning of the forward bias region, and these phenomena have been explained with the help of energy band diagram. An explanation is proposed for the origin of electrical bi-stability in light of the electric field induced charge transfer across the junction, and the NDR phenomena could be attributed to interfacial traps and defect level that arises due to oxygen and zinc interstitial vacancies. Room temperature photoluminescence measurement of ZnO nanorods exhibits the emission peaks at about 466 nm and 566 nm which are attributed to oxygen vacancies and Zn interstitials. A correlation between NDR and blue emission phenomena in the ZnO nanorods due to defects states has been established.
The fastest capillary flow under gravity
Authors: Shou Dahua , Ye Lin , Fan Jintu
Published: June 2014

A single-layer porous structure composed of packed particles is designed to achieve the fastest capillary flow under gravity. The minimum flow time for a fixed flow distance is determined by dynamic competition between capillary pressure, gravity, and viscous effects, all of which have different sensitivities to local microstructures of the porous system. Optimal structural parameters are found that account for the minimum flow time in the single-layer porous medium. The theoretical results obtained can be used for the optimization of porous architectures, achieving excellent liquid management properties.
On the local analytic integrability for a generalized damped nonlinear oscillator equation
Authors: Valls C.
Published: June 2014

We consider the general damped nonlinear oscillator x′ = y, y′ = −a1x − a2xn+1 − a3x2n+1 − y(a4 + a5xn), where ai are real parameters for i = 1, 2, 3, 4, 5 and n is an integer. We note that these class of Liénard differential systems include a large number of physically important nonlinear oscillators. We provide a complete and rigorous characterization of these systems that admit a local analytic first integral in a neighborhood of the origin.
Strengthening metal nanolaminates under shock compression through dual effect of strong and weak graphene interface
Authors: Liu XiaoYi , Wang FengChao , Wu HengAn , Wang WenQiang
Published: June 2014

We use molecular dynamics method to study the strengthening effect of graphene-metal nanolayered composites under shock loading. The graphene interfaces have the advantages of both strong and weak interfacial features simultaneously, which solves a strengthening paradox of interfacial structures. On one hand, the weak bending stiffness of graphene leads to interlayer reflections and weakening the shock wave. On the other hand, the strong in-plane sp2-bonded structures constrain the dislocations and heal the material. The elastic recovery due to graphene interfacial constraints plays an important role in the strengthening effect, and the shock strength can be enhanced by decreasing the interlayer distance. This interface with strong/weak duality should lead to an improved fundamental understanding on the dynamic mechanism of composites with interfacial structures.
Quantitative determination of magnetic beads using a magnetoimpedance-based lab-on-a-chip platform
Authors: Wang Tao , Yang Zhen , Lei Chong , Lei Jian , Zhou Yong
Published: June 2014

This research aims at establishing a lab-on-a-chip platform based on giant magnetoimpedance (GMI) effect for quantitative determination of magnetic beads (MB). A micro-integrated GMI sensor consists of Cr/Cu/NiFe/Cu/NiFe/Al2O3/Cr/Au films that were prepared by Micro-Electro-Mechanical-Systems technology. Au film was integrated into GMI sensor for potential biochemical binding function, and quantitative immobilization of MB was performed on Au film of the GMI sensor. The GMI responses were significantly enhanced at high frequencies after coating MB on the sensing elements. This research offers scientific reference for further study and exploitation on quantitative determination of biomolecules by using the micro-integrated GMI sensor.
Physical mechanism of progressive breakdown in gate oxides
Authors: Palumbo Felix , Lombardo Salvatore , Eizenberg Moshe
Published: June 2014

The definition of the basic physical mechanisms of the dielectric breakdown (BD) phenomenon is still an open area of research. In particular, in advanced complementary metal-oxide-semiconductor (CMOS) circuits, the BD of gate dielectrics occurs in the regime of relatively low voltage and very high electric field; this is of enormous technological importance, and thus widely investigated but still not well understood. Such BD is characterized by a gradual, progressive growth of the gate leakage through a localized BD spot. In this paper, we report for the first time experimental data and a model which provide understanding of the main physical mechanism responsible for the progressive BD growth. We demonstrate the ability to control the breakdown growth rate of a number of gate dielectrics and provide a physical model of the observed behavior, allowing to considerably improve the reliability margins of CMOS circuits by choosing a correct combination of voltage, thickness, and thermal conductivity of the gate dielectric.
Analysis of the electrical properties of Cr/n-BaSi2 Schottky junction and n-BaSi2/p-Si heterojunction diodes for solar cell applications
Authors: Du Weijie , Baba Masakazu , Toko Kaoru , Hara Kosuke O. , Watanabe Kentaro , Sekiguchi Takashi , Usami Noritaka , Suemasu Takashi
Published: June 2014

Current status and future prospects towards BaSi2 pn junction solar cells are presented. As a preliminary step toward the formation of BaSi2 homojunction diodes, diodes with a Cr/n-BaSi2 Schottky junction and an n-BaSi2/p-Si hetero-junction have been fabricated to investigate the electrical properties of the n-BaSi2. Clear rectifying properties were observed in the current density versus voltage characteristics in both diodes. From the capacitance-voltage measurements, the build-in potential, VD, was 0.53 V in the Cr/n-BaSi2 Schottky junction diode, and the Schottky barrier height was 0.73 eV calculated from the thermoionic emission theory; the VD was about 1.5 V in the n-BaSi2/p-Si hetero-junction diode, which was consistent with the difference in the Fermi level between the n-BaSi2 and the p-Si.
A technique for field effect surface passivation for silicon solar cells
Authors: Bonilla Ruy S. , Wilshaw Peter R.
Published: June 2014

The recombination of electric charge carriers at the surface of semiconductors is a major limiting factor in the efficiency of optoelectronic devices, in particular, solar cells. The reduction of such recombination, commonly referred to as surface passivation, is achieved by the combined effect of a reduction in the trap states present at the surface via a chemical component, and the reduction in the charge carriers available for a recombination process, via a field effect component. Here, we propose a technique to field effect passivate silicon surfaces using the electric field effect provided by alkali ions present in a capping oxide. This technique is shown to reduce surface recombination in a controlled manner, and to be highly stable. Surface recombination velocities in the range of 6–15 cm/s are demonstrated for 1 Ω cm n-type float zone silicon using this technique, and they are observed to be constant for over 300 days, without the use of any additional surface chemical treatment. A model of trapping-mediated ionic injection is used to describe the system, and activation energies of 1.8–2 eV are deduced for de-trapping of sodium and potassium alkali ionic species.
Macro- and micro-chaotic structures in the Hindmarsh-Rose model of bursting neurons
Authors: Barrio Roberto , Angeles Martínez M. , Serrano Sergio , Shilnikov Andrey
Published: June 2014

We study a plethora of chaotic phenomena in the Hindmarsh-Rose neuron model with the use of several computational techniques including the bifurcation parameter continuation, spike-quantification, and evaluation of Lyapunov exponents in bi-parameter diagrams. Such an aggregated approach allows for detecting regions of simple and chaotic dynamics, and demarcating borderlines—exact bifurcation curves. We demonstrate how the organizing centers—points corresponding to codimension-two homoclinic bifurcations—along with fold and period-doubling bifurcation curves structure the biparametric plane, thus forming macro-chaotic regions of onion bulb shapes and revealing spike-adding cascades that generate micro-chaotic structures due to the hysteresis.
Theoretical simulation of carrier capture and relaxation rates in quantum-dot semiconductor optical amplifiers
Authors: Wu Yunhu , Zhang Guoping , Guo Ling , Li Xiaoming , Qi Guoqun
Published: June 2014

Based on Auger scattering mechanism, carrier-carrier scattering dynamics between the two-dimensional carrier reservoir (also called wetting layer, i.e., WL) and the confined quantum dot ground and first excited state in quantum-dot semiconductor optical amplifiers (QD-SOAs) are investigated theoretically in this paper. The scattering rates for independent electron and hole densities are calculated. The results show an ultra-fast carrier capture (relaxation) rate up to 1 ps−1, and there is a complex dependence of the Coulomb scattering rates on the WL electron and hole densities. In addition, due to the different effective mass and the level distribution, the scattering rates for electron and hole are very different. Finally, in order to provide a direction to control (increase or decrease) the input current in realistic QD-SOA systems, a simple method is proposed to determine the trends of the carrier recovery rates with the WL carrier densities in the vicinity of the steady-state.
The redshift of surface plasmon resonance of colloidal gold nanoparticles induced by pressure with diamond anvil cell
Authors: Bao Yongjun , Zhao Bin , Hou Dongjie , Liu Junsong , Wang Fei , Wang Xin , Cui Tian
Published: June 2014

Colloidal gold nanoparticles, extensively reagent-purified free and well size-controlled monodisperse, are chosen to study Surface Plasmon Resonance (SPR) under pressure with both in situ experimental measurements and theoretical calculations. The refractive index of water is enhanced by pressure up to 1.2 GPa, while the size, shape, and permittivity of gold nanoparticles change insignificantly. A redshift is shown in the absorption spectrum of gold nanoparticles during the process of increasing pressure and the absorption peaks corresponding to SPR of gold nanoparticles is found to be a linear dependence on the refractive index of water under pressure. It is very important to evaluate the wavelength of the absorption spectrum while we explore the phase transition of materials under pressure with surface enhanced Raman spectroscopy based on gold nanoparticles. These results provide us another method of tailoring SPR with pressure and enhancing the efficiency of detecting the weak optical signal under high pressure.
Nanoscale topographical replication of graphene architecture by artificial DNA nanostructures
Authors: Moon Y. , Shin J. , Seo S. , Park J. , Dugasani S. R. , Woo S. H. , Park T. , Park S. H. , Ahn J. R.
Published: June 2014

Despite many studies on how geometry can be used to control the electronic properties of graphene, certain limitations to fabrication of designed graphene nanostructures exist. Here, we demonstrate controlled topographical replication of graphene by artificial deoxyribonucleic acid (DNA) nanostructures. Owing to the high degree of geometrical freedom of DNA nanostructures, we controlled the nanoscale topography of graphene. The topography of graphene replicated from DNA nanostructures showed enhanced thermal stability and revealed an interesting negative temperature coefficient of sheet resistivity when underlying DNA nanostructures were denatured at high temperatures.
Bi-fluid and neoclassical effect on a Double-Tearing mode in Tore Supra
Authors: Maget Patrick , Lütjens Hinrich , Luciani Jean-François , Garbet Xavier , Février Olivier , Ségui Jean-Luc
Published: June 2014

Tearing modes associated to hollow current profiles are prone to grow in moderate performance plasmas and often constrain the realization of non-inductive discharges in the Tore Supra tokamak, where long pulse duration is performed using Lower Hybrid waves for providing most of the plasma current. The prediction of MHD boundaries in such scenarios is complicated by the importance of diamagnetic effects, combined with curvature stabilization, which determine the stability of these modes. We show that diamagnetic effects, as well as neoclassical forces, are playing a key role in the linear and nonlinear regimes of Double-Tearing Modes on q = 5/3 and q = 2 in these experimental conditions. Detailed comparison with experimental measurements, combined with a scaling in plasma resistivity, give constraints about the experimental equilibrium. Resistive-Interchange Modes destabilized by diamagnetic rotation could also play a role in degrading the energy confinement in the negative magnetic shear region.
Anisotropic ferroelectric properties of anisotropically strained epitaxial NaNbO3 films
Authors: Cai B. , Schwarzkopf J. , Hollmann E. , Schmidbauer M. , Abdel-Hamed M. O. , Wördenweber R.
Published: June 2014

Epitaxial c-axis oriented NaNbO3 films are grown on (110) oriented NdGaO3 substrates. Due to the incorporated lattice strain the films show relaxor ferroelectric properties and an in-plane permittivity that is strongly enhanced with respect to unstrained NaNbO3. Moreover, the lattice mismatch between substrate and film leads to an anisotropy in the compressive in-plain strain of −0.67% and −1.33% for the a- and b-direction of the films, respectively. As a consequence, the ferroelectric properties of the film depend strongly on the orientation of the applied electric field. The small anisotropy of the compressive in-plane strain leads to a large anisotropy of the permittivity, a shift of the peak in the temperature dependence of the permittivity, and different freezing temperatures and activation energies Ea of the relaxor ferroelectric film.
Plasmonic near-field coupling induced absorption enhancement and photoluminescence of silver nanorod arrays
Authors: Cheng Zi-Qiang , Zhong Yu-Ting , Nan Fan , Wang Jia-Hong , Zhou Li , Wang Qu-Quan
Published: June 2014

Silver nanorod (Ag NR) arrays with average diameter about 18 nm and period about 50 nm were electrodeposited in anodic aluminum oxide (AAO) templates. The filling factor of Ag NRs in the AAO nanopores could be adjusted by the deposition temperature. The filling factor increased to ∼98% when the deposition temperature decreased to 1 °C. As the filling factor increased, the plasmon absorption intensity of Ag NR arrays was greatly enhanced, and the longitudinal surface plasmon resonance increased faster. Meanwhile, the AgNR:AAO exhibit strong photoluminescence at ∼570 nm, obviously different with that of the bare AAO at ∼495 nm. Our observation revealed the strong near-field plasmon coupling among the Ag NR arrays.
Comparison of direct current and 50 Hz alternating current microscopic corona characteristics on conductors
Authors: Zhang Shuai , Zhang Bo , He Jinliang
Published: June 2014

Corona discharge is one of the major design factors for extra-high voltage and ultra-high voltage DC/AC transmission lines. Under different voltages, corona discharge reveals different characteristics. This paper aims at investigating DC and AC coronas on the microscopic scale. To obtain the specific characteristics of DC and AC coronas, a new measurement approach that utilizes a coaxial wire-cylinder corona cage is designed in this paper, and wires of different diameters are used in the experiment. Based on the measurements, the respective microscopic characteristics of DC and AC coronas are analyzed and compared. With differences in characteristics between DC and AC coronas proposed, this study provides useful insights into DC/AC corona discharges on transmission line applications.
On the scaling behavior of hardness with ligament diameter of nanoporous-Au: Constrained motion of dislocations along the ligaments
Authors: Viswanath R. N. , Polaki S. R. , Rajaraman R. , Abhaya S. , Chirayath V. A. , Amarendra G. , Sundar C. S.
Published: June 2014

The scaling behavior of hardness with ligament diameter and vacancy defect concentration in nanoporous Au (np-Au) has been investigated using a combination of Vickers Hardness, Scanning electron microscopy, and positron lifetime measurements. It is shown that for np-Au, the hardness scales with the ligament diameter with an exponent of −0.3, that is, at variance with the conventional Hall-Petch exponent of −0.5 for bulk systems, as seen in the controlled experiments on cold worked Au with varying grain size. The hardness of np-Au correlates with the vacancy concentration CV within the ligaments, as estimated from positron lifetime experiments, and scales as CV1/2, pointing to the interaction of dislocations with vacancies. The distinctive Hall-Petch exponent of −0.3 seen for np-Au, with ligament diameters in the range of 5–150 nm, is rationalized by invoking the constrained motion of dislocations along the ligaments.
Deep hole traps in undoped n-GaN films grown by hydride vapor phase epitaxy
Authors: Lee In-Hwan , Polyakov A. Y. , Smirnov N. B. , Govorkov A. V. , Usikov A. S. , Helava H. , Makarov Yu. N. , Pearton S. J.
Published: June 2014

Deep hole traps were studied in bulk free-standing GaN crystals and in thinner (10–20 μm) GaN films prepared by hydride vapor phase epitaxy (HVPE) on sapphire. Six hole traps in different combinations were detected in these crystals, H1 (activation energy 0.92–0.94 eV), H2 (0.55 eV), H3 (0.65–0.7 eV), H4 (0.85–0.9 eV), H5 (1.1–1.2 eV), and H6 (0.95–1.05 eV). The dominant traps in all samples were the H5 and H6 traps that were attributed, respectively, to gallium vacancy complexes with oxygen (VGa-O) and substitutional carbon related centers. We associate the H5 hole traps with the red luminescence bands, the H4 hole traps with the green luminescence bands, and the H6 hole traps with the yellow luminescence bands often observed in HVPE GaN. These attributions are based on the low energy thresholds of the deep traps optical excitation spectra and the depth of the respective trap levels.
High efficiency and rapid response superconducting NbN nanowire single photon detector based on asymmetric split ring metamaterial
Authors: Li Guanhai , Wang Shao-Wei , Chen Xiaoshuang , Lu Wei
Published: June 2014

With asymmetric split ring metamaterial periodically placed on top of the niobium nitride (NbN) nanowire meander, we theoretically propose a kind of metal-insulator-metallic metamaterial nanocavity to enhance absorbing efficiency and shorten response time of the superconducting NbN nanowire single photon detector (SNSPD) operating at wavelength of 1550 nm. Up to 99.6% of the energy is absorbed and 96.5% dissipated in the nanowire. Meanwhile, taking advantage of this high efficiency absorbing cavity, we implement a more sparse arrangement of the NbN nanowire of the filling factor 0.2, which significantly lessens the nanowire and crucially boosts the response time to be only 40% of reset time in previous evenly spaced meander design. Together with trapped mode resonance, a standing wave oscillation mechanism is presented to explain the high efficiency and broad bandwidth properties. To further demonstrate the advantages of the nanocavity, a four-pixel SNSPD on 10 μm × 10 μm area is designed to further reduce 75% reset time while maintaining 70% absorbing efficiency. Utilizing the asymmetric split ring metamaterial, we show a higher efficiency and more rapid response SNSPD configuration to contribute to the development of single photon detectors.
The habitat and diet of koalas (Phascolarctos cinereus) in Queensland
Authors: Melzer Alistair , Cristescu Romane , Ellis William , FitzGibbon Sean , Manno Gabriella
Published: June 2014

Descriptions of koala (Phascolarctos cinereus) habitat and diet from 11 sites across Queensland are presented. Koala activity was recorded from 49 regional ecosystems across nine land zones and five bioregions. Thirty-four tree species were identified from an examination of leaf cuticle fragments in faecal pellets. Although the species were from three families and seven genera, 44% of browse species (15) belonged to the myrtaceous subgenus Symphomyrtus. Eleven of these contributed most of the koala diet across all sites. However, most species were present in minor or trace dietary elements. There was also a large number of unidentified species or dietary elements, all of which were usually present in trace amounts. The importance of these minor and trace components is not known. Diet at some sites was founded on a single eucalypt species. Here the likelihood of those sites’ browse resources being lost or degraded by stochastic events, as climate variability increases, raises questions about the persistence of the resident koala populations.
Probing Mechanisms of Aryl–Aryl Bond Cleavages under Flash Vacuum Pyrolysis Conditions
Authors: Jackson Edward A. , Xue Xiang , Cho Hee Yeon , Scott Lawrence T.
Published: June 2014

Several biaryls have been subjected to flash vacuum pyrolysis (FVP) at 1100°C and 0.8–0.9 hPa. Product compositions are reported for the FVP of 9-phenylanthracene (1), 2-bromobiphenyl (5), biphenyl (8), 1,10-diphenylanthracene (12), 9-(2-naphthyl)anthracene (17), and 9,9′-bianthracenyl (20). The experimental results have been used to evaluate four possible mechanistic pathways for the cleavage of aryl–aryl bonds under these conditions: (1) the ‘explosion’ of substituted phenyl radicals; (2) hydrogen atom attachment to an ipso-carbon atom of the biaryl followed by C–C bond cleavage; (3) direct homolysis; and (4) loss of a fragment as an aryne. None of these mechanisms by itself successfully accommodates all of the experimental facts. The data suggest that aryl–aryl bond cleavages under FVP conditions involve at least two different mechanistic pathways and that the relative contributions of the competing pathways probably vary from one biaryl to the next.
Crop yield components – photoassimilate supply- or utilisation limited-organ development?
Authors: Patrick John W. , Colyvas Kim
Published: June 2014

Yield potential is the genome-encoded capacity of a crop species to generate yield in an optimal growth environment. Ninety per cent of plant biomass is derived from the photosynthetic reduction of carbon dioxide to organic carbon (photoassimilates – primarily sucrose). Thus, development of yield components (organ numbers and individual organ masses) can be limited by photoassimilate supply (photosynthesis arranged in series with phloem transport) or by their inherent capacity to utilise imported photoassimilates for growth or storage. To this end, photoassimilate supply/utilisation of crop yield has been quantitatively re-evaluated using published responses of yield components to elevated carbon dioxide concentrations across a selection of key crop species including cereal and pulse grains, fleshy fruits, tubers and sugar storing stems and tap roots. The analysis demonstrates that development of harvested organ numbers is strongly limited by photoassimilate supply. Vegetative branching and, to a lesser extent, flower/pod/fleshy fruit abortion, are the major yield components contributing to sensitivity of organ numbers to photoassimilate supply. In contrast, harvested organ size is partially dependent (eudicots), or completely independent (cereals), of photoassimilate supply. Processes limiting photoassimilate utilisation by harvested organs include membrane transport of soluble sugars and their allocation into polymeric storage products.
The temporal evolution of wildfire ash and implications for post-fire infiltration
Authors: Balfour Victoria N. , Doerr Stefan H. , Robichaud Peter R.
Published: June 2014

Changes in the properties of an ash layer with time may affect the amount of post-fire runoff, particularly by the formation of ash surface crusts. The formation of depositional crusts by ash have been observed at the pore and plot scales, but the causes and temporal evolution of ash layers and associated crusts have not yet been thoroughly investigated. In the long term, ash crusting effects will decrease as the ash layer is removed by wind and water erosion, but in the short term ash crusting could contribute to the observed changes in post-fire runoff. This research addresses these topics by studying the evolution over time of highly combusted ash layers from two high-severity wildfires that occurred in Montana in 2011. More specifically, this research was designed to assess the potential for ash crusts to form and thereby contribute to the observed decreases in infiltration after forest fires. Results indicate that high-combustion ash can evolve due to post-fire rainfall. Plots that exhibited a visible ash crust also displayed a significant decrease in effective porosity and hydraulic conductivity. These decreases in ash layer characteristics were attributed to raindrop compaction and ash hydration resulting in the formation of carbonate crystals, which decreased effective porosity and flow within the ash layer. During this same time period, inorganic carbon content more than doubled from 11 to 26% and bulk density significantly increased from 0.22 to 0.39gcm–3 on crusted plots. Although raindrop impact increased the robustness of the ash crust, mineralogical transformations must occur to produce a hydrologically relevant ash crust. These results indicate that post-fire rainfall is an important control on the properties of the ash layer after burning and on crust formation. The observed temporal changes indicate that the timing of ash sampling can alter the predictions as to whether the ash layer is effecting post-fire infiltration and runoff. Despite the reduction in infiltration capacity, the formation of post-fire ash crusts could prove beneficial to post-fire hazard mitigation by stabilising the ash layer, and reducing aeolian mixing and erosion.
An alcohol-sensing site in the calcium- and voltage-gated, large conductance potassium (BK) channel
Authors: Bukiya Anna N. , Kuntamallappanavar Guruprasad , Edwards Justin , Singh Aditya K. , Shivakumar Bangalore , Dopico Alex M.
Published: June 2014

Significance

Alcohol (ethanol) is one of the most widely consumed psychoactive agents. Ethanol’s targets in the body include voltage/calcium-gated, large conductance potassium (BK) channels. Here we identified and characterized for the first time an alcohol-sensing site in BK channel-forming proteins. Our discovery opens new ground for rational design of tools to counteract the effects of ethanol intoxication that are mediated by BK channels. We anticipate that genetic or epigenetic modifications of the BK channel ethanol-recognition site could explain differential sensitivity to ethanol. Finally, since individuals with low sensitivity to ethanol are prone to developing heavy drinking habits, genetic, epigenetic or other mechanisms acting at the newly identified BK channel ethanol-recognition site might be considered as potential predictors for developing alcohol preference.
Sources and sinks of carbonyl sulfide in an agricultural field in the Southern Great Plains
Authors: Maseyk Kadmiel , Berry Joseph A. , Billesbach Dave , Campbell John Elliott , Torn Margaret S. , Zahniser Mark , Seibt Ulli
Published: June 2014

Significance

We report observations of ecosystem carbonyl sulfide (COS) and CO2fluxes that resolve key gaps in an emerging framework for using concurrent COS and CO2measurements to quantify terrestrial gross primary productivity. We show for the first time that leaf relative uptake ratios of COS and CO2during photosynthesis measured in the field vary systematically with light. We established that nocturnal COS uptake by vegetation is a significant component of daily net ecosystem COS fluxes. We also quantified a close correlation of soil COS fluxes with soil temperature. The small soil contribution to net ecosystem fluxes confirms that vegetation uptake is the dominant ecosystem COS flux in the growing season, a prerequisite for COS-based flux partitioning approaches.
Oxytocin promotes social bonding in dogs
Authors: Romero Teresa , Nagasawa Miho , Mogi Kazutaka , Hasegawa Toshikazu , Kikusui Takefumi
Published: June 2014

Significance

Although the positive impact of social bonds on individual’s fitness has recently been demonstrated, the mechanisms underlying the motivation to form long-term associations remain largely unknown. Current evidence shows that oxytocin modulates social behavior but evidence of its effects in bond maintenance remains scant, especially in nonreproductive contexts. We provide evidence that in the domestic dog oxytocin enhances social motivation to approach and affiliate with conspecifics and human partners, which constitutes the basis for the formation of any stable social bond. Furthermore, endogenous oxytocin levels increased after dogs engaged in affiliation with their dog partners, indicating a stimulation of the oxytocin system during social interactions. Our findings highlight the important role that oxytocin has in the expression of sociality in mammals.
RETRACTED: Regulation of cell proliferation and migration by p62 through stabilization of Twist1
Authors: Qiang Lei , Zhao Baozhong , Ming Mei , Wang Ning , He Tong-Chuan , Hwang Seungmin , Thorburn Andrew , He Yu-Ying
Published: June 2014

The selective autophagy substrate p62 serves as a molecular link between autophagy and cancer. Suppression of autophagy causes p62 accumulation and thereby contributes to tumorigenesis. Here we demonstrate that autophagy deficiency promotes cell proliferation and migration through p62-dependent stabilization of the oncogenic transcription factor Twist1. p62 binds to Twist1 and inhibits degradation of Twist1. In mice, p62 up-regulation promotes tumor cell growth and metastasis in a Twist1-dependent manner. Our findings demonstrate that Twist1 is a key downstream effector of p62 in regulation of cell proliferation and migration and suggest that targeting p62-mediated Twist1 stabilization is a promising therapeutic strategy for prevention and treatment of cancer.
Genetically engineering
Synechocystis
sp. Pasteur Culture Collection 6803 for the sustainable production of the plant secondary metabolite
p
-coumaric acid
Authors: Xue Yong , Zhang Yan , Cheng Dan , Daddy Soumana , He Qingfang
Published: June 2014

Significance

The photosynthetic cyanobacteria are promising candidates for the sustainable production of a plethora of plant secondary metabolites, which are difficult to produce and purify in other systems. Many secondary metabolites are beneficial to human health. For instance, the phenylpropanoids, which are derived from
p
-coumaric acid, have anticancer, antiviral, and anti-inflammatory properties. Here, we constructed a strain of cyanobacterium
Synechocystis
6803 that heterologously expressed a foreign gene encoding a tyrosine ammonia lyase, which converts tyrosine into
p
-coumaric acid and lacked a native laccase that degrades
p-
coumaric acid. The strain secreted ∼82.6 mg/L
p
-coumaric acid, which was readily extracted and purified from the culture medium. We thus show that cyanobacteria may indeed be used to sustainably produce plant secondary metabolites.