bluuebunny/crossref_metadata_2025 huggingface dataset:
Foraging on the potential energy surface: A swarm intelligence-based optimizer for molecular geometry
Authors: Wehmeyer Christoph , Falk von Rudorff Guido , Wolf Sebastian , Kabbe Gabriel , Schärf Daniel , Kühne Thomas D. , Sebastiani Daniel
Published: November 2012

We present a stochastic, swarm intelligence-based optimization algorithm for the prediction of global minima on potential energy surfaces of molecular cluster structures. Our optimization approach is a modification of the artificial bee colony (ABC) algorithm which is inspired by the foraging behavior of honey bees. We apply our modified ABC algorithm to the problem of global geometry optimization of molecular cluster structures and show its performance for clusters with 2–57 particles and different interatomic interaction potentials.
Magnetocaloric and magnetotransport properties in RRhSn (R = Tb-Tm) series
Authors: Gupta Sachin B. , Suresh K. G. , Nigam A. K.
Published: November 2012

We have synthesized polycrystalline RRhSn (R = Tb-Tm) compounds, which crystallize in the hexagonal structure with space group P6¯2m. All the compounds, except HoRhSn, are antiferromagnetic at low temperatures. TbRhSn and DyRhSn show multiple magnetic transitions and metamagnetic behavior. Heat capacity and electrical resistivity data in different temperature regimes were fitted to identify various contributions to them. Magnetocaloric effect (MCE) in all the compounds has been calculated in terms of the isothermal magnetic entropy change and the adiabatic temperature change. ErRhSn and TmRhSn show Schottky anomaly in the heat capacity data. Among the compounds studied, HoRhSn shows the maximum adiabatic temperature change of 6.5 K for a field of 50 kOe. DyRhSn and TmRhSn also show large positive magnetocaloric effect below 10 K. A sign reversal accompanied by a large positive magnetoresistance (MR) at low temperatures appears to be a common feature in this series of compounds. Narrow domain wall dynamics appears to be the main reason behind the large positive magnetoresistance in all the compounds.
Coupling characteristics of point defects modes in two-dimensional magnonic crystals
Authors: Yang Hui , Yun Guohong , Cao Yongjun
Published: November 2012

The coupling characteristics of two-point defects modes and multi-point defects modes in two-dimensional magnonic crystals composed of Fe square rods/EuO square lattices are studied based on the plane-wave expansion method under supercell approximation. The results show that the coupling degree of these defect modes depends not only on the distance between defect bodies, but also on the arrangement direction of point defects. The phase of precession of defect modes' magnetization distributions varies as the distance between the defects changes. These magnonic crystals with multi-point defects can be used as the fabricating materials of the directional spin-wave filters or the narrow band spin-wave waveguides.
Efficient excitation and detection of standing spin wave in Permalloy film: Demonstration of spin wave resonator
Authors: Kiseki K. , Yakata S. , Kimura T.
Published: November 2012

A magnetic resonator consisting of periodical nonmagnetic electrodes on a ferromagnetic metallic film has been fabricated. We demonstrated that the resonator efficiently excites the standing magneto-static surface spin wave with the specific wavelength, which can be controlled by the interval of the periodical electrode. The operation frequency over 5 GHz was confirmed at the interval of 4 μm under a small bias magnetic field less than 100 Oe. The optimization of the electrode pattern for the efficient detection of the standing spin wave was also demonstrated.
Two-dimensional Bessel-like surface plasmon-polariton beams
Authors: Regan Charles J. , Grave de Peralta Luis , Bernussi Ayrton A.
Published: November 2012

We present experimental evidence of non-diffracting two-dimensional Bessel-like surface plasmon-polariton (SPP) beams using the simultaneous excitation of two grating couplers forming an angle. The Bessel-like SPP beam properties were verified experimentally using the plasmon-coupled leakage radiation microscopy technique. The good agreement between simulations and measured intensity beam profiles confirms the effectiveness of the grating-coupler approach. Our results revealed that the spreading and propagation length characteristics of the Bessel-like SPP beams are primarily influenced by the angle between the grating couplers.
Reliable DFT-based estimates of cohesive energies of organic solids: The anthracene crystal
Authors: Sancho-García J. C. , Olivier Y.
Published: November 2012

Prediction of cohesive energy of crystals is of particular interest in order to understand crystal growth mechanisms for further molecular engineering. In this study, we have aimed at assessing the accuracy of dispersion-corrected calculations (DFT-D2, DFT-D3, and DFT-NL) in reproducing the experimental cohesive energy of the anthracene crystal. Preliminary comparison of the interaction energies calculated at revPBE(0)-D3 and revPBE(0)-NL levels in isolated dimers (taken from the crystalline structure) with benchmark calculations performed at the SCS-MP2 and LPNO-pCCSD1a level enlightens the reliability of these DFT-based methods for which the best accuracy achieved is within 1–2 kJ/mol of the ab initio methods. Interestingly, the evaluation of the cohesive energy reveals that 35%–37% of this energy come from the consideration of a second coordination shell. Three-body interaction energy correction is calculated for revPBE-D3 functional and happens to reduce the cohesive energy of an anthracene nanoaggregate by 7 kJ/mol, while similar results are obtained with revPBE(0)-NL functional. In the end, dispersion-corrected estimates of the cohesive energy show sufficiently good agreement with experiment.
Ionization enhancement in silicon clusters and germanium atoms in the presence of zirconium
Authors: Ross Matt W. , Castleman A. W.
Published: November 2012

Molecules/clusters have been shown to undergo an enhancement in ionization under ultrafast laser pulses. This enhancement results in the lowering of the laser intensity required to observe ion signal from higher atomic charge states resulting from Coulomb explosion of clusters. Here, we explore the effect of using an early-group transition metal as an electron source in the formation of small silicon clusters on the observed enhancement in ionization. Intensity selective scanning is used to measure the onset of ion signal for the atomic charge states of silicon, germanium, zirconium, and oxygen. Additionally, the kinetic energy released values for the resulting high charge states of silicon are measured and compared to those previously observed using a copper electron source. A significant increase in ionization enhancement is observed upon using zirconium metal, despite a decrease in cluster size. Germanium metal with zirconium is studied for comparison and shows a larger enhancement in ion signal than silicon, indicating that atomic mass may be significant.
Band-edge density-of-states and carrier concentrations in intrinsic and p-type CuIn1−xGaxSe2
Authors: Chen Rongzhen , Persson Clas
Published: November 2012

The electronic structures of chalcopyrite CuIn1−xGaxSe2 have recently been reported to have strongly anisotropic and non-parabolic valence bands (VBs) even close to the Γ-point VB maximum. Also, the lowest conduction band (CB) is non-parabolic for energies 50–100 meV above the CB minimum. The details in the band-edge dispersion govern the material's electrical properties. In this study, we, therefore, analyze the electronic structure of the three uppermost VBs and the lowest CB in CuIn1−xGaxSe2 (x = 0, 0.5, and 1). The parameterized band dispersions are explored, and the density-of-states (DOS) as well as the constant energy surfaces are calculated and analyzed. The carrier concentration and the Fermi energy EF in the intrinsic alloys as functions of the temperature is determined from the DOS. The carrier concentration in p-type materials is modeled by assuming the presence of Cu vacancies as the acceptor type defect. We demonstrate that the non-parabolicity of the energy bands strongly affects the total DOS. Therefore, it is important to take into account full band dispersion of the VBs and CB when analyzing the free carrier concentration, like for instance, in studies of electronic transport and/or measurements that involve strong excitation conditions.
Ultrabroadband terahertz conductivity of Si nanocrystal films
Authors: Cooke D. G. , Meldrum A. , Uhd Jepsen P.
Published: November 2012

The terahertz conductivity of silicon nanoparticles embedded in glass with varying density is studied with ultra-broadband terahertz spectroscopy on picosecond time scales following fs optical excitation. The transition from relatively isolated charge carriers to densities which allow inter-particle transport is clearly observed. For the times immediately following carrier injection, we observe Drude-like long range transport that is rapidly replaced with a localized response on picosecond time scales. The localized response can be very well described by a phenomenological Drude-Smith model, verifying the applicability of this simple model to the conductivity of nanoparticle ensembles over the entire THz spectral window.
Stability and half-metallicity of the (001) and (111) surfaces of CrTe with rocksalt structure
Authors: Gao G. Y. , Yao Wei , Han H. P. , Khalaf Al-zyadi J. M. , Yao K. L.
Published: November 2012

We extend the recent study on above-room-temperature half-metallic ferromagnetism in bulk rocksalt CrTe [Y. Liu, S. K. Bose, and J. J. Kudrnovský, Phys. Rev. B 82, 094435 (2010)] to the (001) and (111) surfaces by using the first-principles calculations. We show that the Te-terminated (111) surface is energetically more stable than both the (001) and the Cr-terminated (111) surfaces over the whole effective Cr chemical potential, and the surface stability of the Te-terminated (111) surface of rocksalt CrTe is comparable with that of the Te-terminated (001) surface of experimental zinc-blende CrTe. In addition, both the (001) and (111) surfaces of rocksalt CrTe retain the bulk half-metallicity. The atomic magnetic moments at the (111) surfaces are greatly different from those in the bulk rocksalt CrTe due to the breakdown of Cr-Te bond at the (111) surface, but the differences are very small for the case of the (001) surface due to the existence of Cr-Te bond at the (001) surface. These results indicate that it is feasible to fabricate the half-metallic CrTe thin films with rocksalt structure other than zinc-blende one.
Evolution of surface morphology and electronic structure of few layer graphene after low energy Ar+ ion irradiation
Authors: Al-Harthi S. H. , Kara'a A. , Hysen T. , Elzain M. , Al-Hinai A. T. , Myint M. T. Z.
Published: November 2012

We report on co-existing dual anisotropy ripple formation, sp bonding transformation, and variation in the delocalized π electron system in 1 keV Ar+ ion irradiated few-layer graphene surfaces. Ripples in directions, perpendicular and parallel to the ion beam were found. The irradiation effect and the transition from the sp2-bonding to sp3-hybridized state were analyzed from the deconvolution of the C (1s) peak and from the shape of the derivative of the Auger transition spectra. The results suggest a plausible mechanism for tailoring of few-layer graphene electronic band structure with interlayer coupling tuned by the ion irradiation.
Selectively grown photonic crystal structures for high efficiency InGaN emitting diodes using nanospherical-lens lithography
Authors: Wei Tongbo , Wu Kui , Lan Ding , Yan Qingfeng , Chen Yu , Du Chengxiao , Wang Junxi , Zeng Yiping , Li Jinmin
Published: November 2012

We report a low-cost and high-throughput process for the fabrication of two-dimensional SiO2 photonic crystal (PhC) by nanospherical-lens photolithography method to improve the light extraction of GaN-based light-emitting diodes (LEDs). The PhC structures were realized by the selective area growth of p-GaN using SiO2 nanodisks, which were patterned utilizing a self-assembled nanosphere as an optical lens. Without prejudice to the electrical properties of LEDs, the light output power (at 350 mA) of LEDs with the SiO2 and corresponding air-hole PhC was enhanced by 71.3% and 49.3%, respectively, compared to that without PhC. The LEDs with selectively grown PhC structures were found to exhibit partial compression strain release and reduced emission divergence. The finite-difference time-domain simulation was also performed to further reveal the emission characteristics of PhC LEDs.
Size-dependent thermal conductivity in nanosystems based on non-Fourier heat transfer
Authors: Ma Yanbao
Published: November 2012

Based on a phonon hydrodynamic equation, we derive an analytical model to predict the effective thermal conductivity along dielectric thin films or nanowires with smooth wall surface. The model contains only two parameters: bulk thermal conductivity and Knudsen number, no other fitting parameter included. The predictions from the simple model agree approximately with available experimental data in silicon nanostructures and it outperforms other analytical models based on the Boltzmann transport equation.
On the suppression and significance of ghost transmission in electron transport modeling of single molecule junctions
Authors: Pal Partha Pratim , Dunietz Barry D.
Published: November 2012

The difficulty in achieving experimental control over a metal-molecule-metal junction formation hinders the understanding of the relationship between the contact geometry and electron transmittance. Computational studies on the other hand have the potential to resolve structural effects on the transport in molecular junctions. In a recent computational effort substantial transport was indicated even in the case where all the junction atoms were removed, while their corresponding atomic basis functions were included in the basis set (i.e., ghost atoms). In this report we explain the origin of the artifact termed as “ghost transmission.” We provide a systematic analysis of the factors that enhance or suppress the artifact. We find that symmetric electronic densities at the two metal-molecule interfaces can lead to an amplification of the artificial transmission. In addition, interaction between an unpaired electron of the left electrode with one in the right electrode results with a substantial increase in “ghost transmission.” Finally we find that a self-consistent single particle Green's function formalism that solves the junction electronic structure self-consistently with respect to the electrodes self-energies, reduces the artifact substantially.
Optically pumped cesium plasma neutralization of space charge in photon-enhanced thermionic energy converters
Authors: Ito Tsuyohito , Cappelli Mark A.
Published: November 2012

Photon-enhanced thermionic emission from semiconducting cathodes is a promising means of increasing cathode current density in low temperature vacuum thermionic energy devices [J. W. Schwede et al., Nature Mater. 9, 762 (2010)]. However, the space charge resulting from high emission current densities prevents emitted electrons from reaching the collector, even with gaps as small as 100 μm and at voltages as high as 1 V. We demonstrate by particle-in-cell simulations that one possible solution to overcoming the space charge is to add cesium filling and generation of a space charge-neutralizing plasma by continuous laser excitation of the cesium resonance level.
Local lifetime and luminescence efficiency for the near-band-edge emission of freestanding GaN substrates determined using spatio-time-resolved cathodoluminescence
Authors: Ishikawa Y. , Tashiro M. , Hazu K. , Furusawa K. , Namita H. , Nagao S. , Fujito K. , Chichibu S. F.
Published: November 2012

Spatio-time-resolved cathodoluminescence measurements were carried out on low threading dislocation density freestanding GaN substrates grown by hydride vapor phase epitaxy. High-resolution cathodoluminescence imaging allows for visualization of nonradiative recombination channels in the vicinity of accidentally formed inversion domain boundaries. Local cathodoluminescence lifetimes (τCL) for the near-band-edge (NBE) emission are shown to be sensitively position dependent. A linear relation between the equivalent internal quantum efficiency (ηinteq) and τCL for the NBE emission was observed at room temperature under a weak excitation condition, and spatially resolved excitation led to the observation of the highest ηinteq of 20% with τCL of 3.3 ns.
Reflection loss mechanism of single layer absorber for flake-shaped carbonyl-iron particle composite
Authors: Wang Tao , Han Rui , Tan Guoguo , Wei Jianqiang , Qiao Liang , Li Fashen
Published: November 2012

The reflection loss (RL) properties including the frequency, intensity, and bandwidth of absorption peaks for the flake-shaped carbonyl-iron particle/paraffin composite were investigated in detail. By measuring the reflection coefficient of the composite without (S11-OPEN) and with (S11-SHORT) a backed metal plate, the origin of the RL peak was directly verified. The separated electromagnetic wave energy reflected at the air-absorber interface and the absorber-metal plate interface was achieved from S11-OPEN and S11-SHORT parameters, and they were used to explain the intensity variation of the RL peak. The bandwidth of the RL peak was also deduced from viewpoint of interface reflection waves. The calculated bandwidth from the derived formula agreed well with the experimental data.
Čerenkov nonlinear diffraction in random nonlinear photonic crystal of strontium tetraborate
Authors: Vyunishev A. M. , Aleksandrovsky A. S. , Zaitsev A. I. , Slabko V. V.
Published: November 2012

Čerenkov-type second harmonic generation of femtosecond pulses in random one-dimensional nonlinear photonic crystal of strontium tetraborate is investigated experimentally and theoretically. Sidebands in angular-spectral dependence of generated second harmonic were detected and found to be in perfect agreement with calculations. Spectral maximum of generated radiation experiences deviation from Čerenkov relation due to influence of nonlinear photonic crystal structure. Pulse duration and local spectrum of Čerenkov second harmonic are measured and found to be in fair agreement with each other.
Morphology and in-plane thermal conductivity of hybrid graphene sheets
Authors: Liu Bo , Reddy C. D. , Jiang Jinwu , Baimova Julia A. , Dmitriev Sergey V. , Nazarov Ayrat A. , Zhou Kun
Published: November 2012

This paper investigates the morphology and in-plane thermal conductivity of hybrid graphene sheets (HGSs), which consist of un-hydrogenated and single-side or double-side hydrogenated strips, via molecular dynamics simulation. The study shows that the hydrogenation styles and hydrogen coverage significantly affect the morphology and thermal conductivity of HGSs. The thermal conductivity of HGSs decreases dramatically, compared to that of pure graphene sheets, and the magnitude falls in the range of 30%-75%. Such differences are explained by conducting the phonon spectra analysis.
Collective thermodiffusion of colloidal suspensions
Authors: Lüsebrink Daniel , Ripoll Marisol
Published: November 2012

The thermophoretic behavior of concentrated colloidal suspensions can be understood as the sum of single particle and collective effects. Here, we present a simulation model to investigate the particularities of the collective thermodiffusive effects in concentrated uncharged solutions, where the influence of different colloid-colloid interactions is analyzed. The concentration dependence found in our simulations qualitatively agrees with experimental results. Colloids with repulsive interactions are found to accumulate more effectively than the solvent in the warm areas, such that the corresponding Soret coefficients are negative and decrease with increasing concentration. The accumulation of colloids in the cold regions is facilitated by attraction, such that colloids with attractive interactions have larger values of the Soret coefficient. A thermodynamic argument that explains our results from equilibrium quantities is discussed as well.
Effects of the Al cathode evaporation rate on the performance of organic solar cells
Authors: Kim Junwoo , Kim Jung-Su , Kwak Sun-Woo , Yu Jong-Su , Jang Yunseok , Jo Jeongdai , Lee Taik-Min , Kim Inyoung
Published: November 2012

In this study, the effects of the interface structure between Al cathode and polymer photo-active thin film are investigated regarding the performance of bulk heterojunction polymer solar cells by changing the Al cathode e-beam evaporation rate. The formation of Al-polymer complex interlayers increases open circuit voltage (Voc) above 0.7 V while decreasing the short circuit current and fill factor. These can be improved, however, without much loss of Voc by increasing the evaporation rate, which results in power conversion efficiency enhancement from 1.35% to 3.6%.
Effects of oxygen on electron beam induced deposition of SiO2 using physisorbed and chemisorbed tetraethoxysilane
Authors: Bishop James , Toth Milos , Phillips Matthew , Lobo Charlene
Published: November 2012

Electron beam induced deposition (EBID) is limited by low throughput and purity of as-grown material. Co-injection of O2 with the growth precursor is known to increase both the purity and deposition rate of materials such as SiO2 at room temperature. Here, we show that O2 inhibits rather than enhances EBID from tetraethoxysilane (TEOS) precursor at elevated temperatures. This behavior is attributed to surface site competition between chemisorbates at elevated temperature, and TEOS decomposition by atomic oxygen produced through electron dissociation of physisorbed O2 at room temperature.
Band alignment and interfacial structure of ZnO/Ge heterojunction investigated by photoelectron spectroscopy
Authors: Singh S. D. , Ajimsha R. S. , Sahu Vikas , Kumar Ravi , Misra P. , Phase D. M. , Oak S. M. , Kukreja L. M. , Ganguli Tapas , Deb S. K.
Published: November 2012

Studies on band-offset and band-alignment of heterojunction of highly c-axis oriented ZnO thin films grown on n-Ge (1 1 1) by pulsed laser deposition show a type-II band alignment with the valence band offset (ΔEV) of 3.1 ± 0.2 eV. The valence band spectra of this heterojunction show band onsets corresponding to Ge, interfacial GeOx, and ZnO layers. This observation also enabled us to determine ΔEV of ZnO/GeOx heterojunction to be 1.4 ± 0.2 eV. These studies provide further insight into the band alignment of ZnO/GeOx/Ge system wherein the observed large value of ΔEV of ZnO/Ge can be used for heterojunction based optoelectronic devices.
Microstructural heterogeneity and dynamic shear localization
Authors: Osovski S. , Rittel D.
Published: November 2012

Dynamic shear localization attracted interest as both experimental and theoretical evidence suggested that its origins are not only due, as believed, to thermal softening, but are most likely related to microstructural evolutions, the latter being driven by a critical value of the stored strain energy. Yet, nothing is known about the effects of the distribution (heterogeneity) of this stored energy at the microstructural level. Using the well-known concept of Shannon's entropy, we systematically compare different heterogeneities, and conclude that small amounts of microstructural heterogeneity may significantly influence shear localization, as opposed to larger values of homogeneously distributed strain energy.
Internal quantum efficiency in AlGaN with strong carrier localization
Authors: Mickevičius J. , Tamulaitis G. , Shur M. , Shatalov M. , Yang J. , Gaska R.
Published: November 2012

The emission efficiency droop and internal quantum efficiency (IQE) in AlGaN epilayers and heterostructures were investigated by studying photoluminescence intensity dependence on excitation power density at different temperatures in the range from 8 to 300 K in three AlGaN samples with similar Al content (33%-35%) and different strength of carrier localization: an epilayer and multiple quantum wells with well widths of 5.0 and 2.5 nm. It is shown that the phenomena leading to the efficiency droop strongly influence the photoluminescence intensity dependence on temperature and, therefore, affect the estimation of IQE based on this dependence. A procedure to optimize the determination of IQE is proposed.
Heterojunction photodiode fabricated from hydrogen treated ZnO nanowires grown on p-silicon substrate
Authors: Shao Dali , Yu Mingpeng , Lian Jie , Sawyer Shayla
Published: November 2012

A heterojunction photodiode was fabricated from ZnO nanowires (NWs) grown on a p-type Si (100) substrate using a hydrothermal method. Post growth hydrogen treatment was used to improve the conductivity of the ZnO NWs. The heterojunction photodiode showed diode characteristics with low reverse saturation current (5.58 × 10−7 A), relatively fast transient response, and high responsivity (22 A/W at 363 nm). Experiments show that the photoresponsivity of the photodiode is dependent on the polarity of the voltages. The photoresponsivity of the device was discussed in terms of the band diagrams of the heterojunction and the carrier diffusion process.
Thermal conductivity of composites with hybrid carbon nanotubes and graphene nanoplatelets
Authors: Chu Ke , Li Wen-sheng , Jia Cheng-chang , Tang Fu-ling
Published: November 2012

An analytical model of the effective thermal conductivity in composites with hybrid carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) is presented by incorporating the percolation effect with an effective medium approach. The theoretical results are found to be in reasonably good agreement with recently published experimental data which well describe the synergistic effect of thermal conductivity enhancement in hybrid CNT/GNP composites. Theoretical analysis shows that the thermal conductivity enhancement mainly relies on a GNP percolation effect triggered by the presence of CNTs, rather than the isolated CNTs and GNPs, even at very low GNP percolation threshold.
Achromatic polarization splitting effect of metallic gratings with sub-50 nm wide slits
Authors: Kang Guoguo , Fang Yue , Vartiainen Ismo , Tan Qiaofeng , Wang Yongtian
Published: November 2012

We report on a broadband polarization splitting phenomenon in an aluminum grating with its period much smaller than the wavelength of incident light. Under oblique incidence, grating is highly transparent for one polarization, but it is opaque and reflects the orthogonal polarization. By using the Fourier modal method and planar waveguide theory, we show that, comparing with the traditional metallic wire grid polarizers, the improved confinement of TM0 mode within the sub-50 nm wide grating slits is responsible for this polarization splitting effect.
Secondary-electrons-induced cathode plasma in a relativistic magnetron
Authors: Queller T. , Gleizer J. Z. , Krasik Ya. E.
Published: November 2012

Results of time- and space-resolved spectroscopic studies of cathode plasma during a S-band relativistic magnetron operation and a magnetically insulated diode having an identical interelectrode gap are presented. It was shown that in the case of the magnetron operation, one obtains an earlier, more uniform plasma formation due to energetic electrons' interaction with the cathode surface and ionization of desorbed surface monolayers. No differences were detected in the cathode's plasma temperature between the magnetron and the magnetically insulated diode operation, and no anomalous fast cathode plasma expansion was observed in the magnetron at rf power up to 350 MW.
“Boiling” in the water evaporating meniscus induced by Marangoni flow
Authors: Liu Xiang , Guo Dan , Xie Guoxin , Liu Shuhai , Luo Jianbin
Published: November 2012

A counterintuitive phenomenon, “boiling,” was directly observed near the contact line of the pure water meniscus formed in a ball and disk configuration, when the ball temperature was far lower than the saturation temperature of water. The number of the emerging bubbles due to “boiling” increased with ball temperature rising; each bubble would expanse initially and then collapse. When two surfaces were heated to the same temperature, “boiling” disappeared. It was proposed that the temperature gradient between the two surfaces initiated Marangoni flow, which hindered flow toward the film, resulting in the negative pressure and cavitation in the liquid film.
Dynamic electrostatic force microscopy in liquid media
Authors: Gramse G. , Edwards M. A. , Fumagalli L. , Gomila G.
Published: November 2012

We present the implementation of dynamic electrostatic force microscopy in liquid media. This implementation enables the quantitative imaging of local dielectric properties of materials in electrolyte solutions with nanoscale spatial resolution. Local imaging capabilities are obtained by probing the frequency-dependent and ionic concentration-dependent electrostatic forces at high frequency (>1 MHz), while quantification of the interaction forces is obtained with finite-element numerical calculations. The results presented open a wide range of possibilities in a number of fields where the dielectric properties of materials need to be probed at the nanoscale and in a liquid environment.
Electrical effect of titanium diffusion on amorphous indium gallium zinc oxide
Authors: Choi Seung-Ha , Jung Woo-Shik , Park Jin-Hong
Published: November 2012

In this work, thermal diffusion phenomenon of Ti into amorphous indium gallium zinc oxide (α-IGZO) was carefully investigated with secondary ion mass spectroscopy, I-V, and Rs measurement systems and HSC chemistry simulation tool. According to the experimental and simulated results, the diffused Ti atoms were easily oxidized due to its lowest oxidation free energy. Since oxygen atoms were decomposed from the α-IGZO during the oxidation of Ti, the number of oxygen vacancies working as electron-donating sites in α-IGZO was dramatically increased, contributing to the decrease of resistivity (ρ) from 1.96 Ω cm (as-deposited α-IGZO) to 1.33 × 10−3 Ω cm (350 °C annealed α-IGZO).
Photomixing in topological insulator HgTe/CdTe quantum wells in terahertz regime
Authors: Chen Qinjun , Sin Ang Yee , Lewis R. A. , Wang Xiaolin , Zhang Chao
Published: November 2012

We reveal that topological insulators (TI) HgTe/CdTe quantum well have a strong nonlinear optical property in the three-photon mixing. While the gapless surface state in TI can exhibit strong nonlinear effect due to the linear energy dispersion, the nonparabolic energy dispersion of the bulk state is responsible for the photo mixing effect reported here. To produce response at terahertz frequency regime from femtosecond electrical fields, the mixing efficiency is around 10−4 comparable to that of nonlinear semiconductor crystals. The optimal temperature for this nonlinear effect is around 100 K. The results suggest a potential application of TI in terahertz photonics.
Momentum transfer and flow induction in a dielectric barrier discharge plasma actuator
Authors: Abe T. , Takagaki M. , Yamada K.
Published: November 2012

The flow induction process resulting from a dielectric barrier discharge plasma actuator was experimentally investigated by a flow visualization method. This method enables a detailed examination of the flow induction process. The overall behavior as well as the detailed temporal and spatial behavior of the flow induction process was clarified. The induced flow originated from the vicinity of an exposed electrode edge, and similar to a wall jet, it smoothly spread over the surface until a vortex was generated at the tip of the wall jet. Even after the vortex disappeared, the wall jet continued to extend. This wall jet was classified into two distinct regions. The first region contained the wall jet extending from the electrode edge to the location where the vortex was generated. In this region, active momentum coupling occurred; therefore, the flow was actively induced. During active momentum transfer in the acceleration region, the periodic inflation of the wall jet thickness was synchronized with the decreasing phase of the applied high-voltage input, which suggested different mechanisms of momentum transfer during the increasing and decreasing phases of the high-voltage input. The second region was an extension of the first one and was formed through the inertia of the flow originating from the first region.
Highly efficient photochemical HCOOH production from CO2 and water using an inorganic system
Authors: Yotsuhashi Satoshi , Hashiba Hiroshi , Deguchi Masahiro , Zenitani Yuji , Hinogami Reiko , Yamada Yuka , Deura Momoko , Ohkawa Kazuhiro
Published: November 2012

We have constructed a system that uses solar energy to react CO2 with water to generate formic acid (HCOOH) at an energy conversion efficiency of 0.15%. It consists of an AlGaN/GaN anode photoelectrode and indium (In) cathode that are electrically connected outside of the reactor cell. High energy conversion efficiency is realized due to a high quantum efficiency of 28% at 300 nm, attributable to efficient electron-hole separation in the semiconductor's heterostructure. The efficiency is close to that of natural photosynthesis in plants, and what is more, the reaction product (HCOOH) can be used as a renewable energy source.
Low-affinity B cells transport viral particles from the lung to the spleen to initiate antibody responses
Authors: Bessa Juliana , Zabel Franziska , Link Alexander , Jegerlehner Andrea , Hinton Heather J. , Schmitz Nicole , Bauer Monika , Kündig Thomas M , Saudan Philippe , Bachmann Martin F.
Published: November 2012

The lung is an important entry site for pathogens; its exposure to antigens results in systemic as well as local IgA and IgG antibodies. Here we show that intranasal administration of virus-like particles (VLPs) results in splenic B-cell responses with strong local germinal-center formation. Surprisingly, VLPs were not transported from the lung to the spleen in a free form but by B cells. The interaction between VLPs and B cells was initiated in the lung and occurred independently of complement receptor 2 and Fcγ receptors, but was dependent upon B-cell receptors. Thus, B cells passing through the lungs bind VLPs via their B-cell receptors and deliver them to local B cells within the splenic B-cell follicle. This process is fundamentally different from delivery of blood or lymph borne particulate antigens, which are transported into B cell follicles by binding to complement receptors on B cells.
Palette of fluorinated voltage-sensitive hemicyanine dyes
Authors: Yan Ping , Acker Corey D. , Zhou Wen-Liang , Lee Peter , Bollensdorff Christian , Negrean Adrian , Lotti Jacopo , Sacconi Leonardo , Antic Srdjan D. , Kohl Peter , Mansvelder Huibert D. , Pavone Francesco S. , Loew Leslie M.
Published: November 2012

Optical recording of membrane potential permits spatially resolved measurement of electrical activity in subcellular regions of single cells, which would be inaccessible to electrodes, and imaging of spatiotemporal patterns of action potential propagation in excitable tissues, such as the brain or heart. However, the available voltage-sensitive dyes (VSDs) are not always spectrally compatible with newly available optical technologies for sensing or manipulating the physiological state of a system. Here, we describe a series of 19 fluorinated VSDs based on the hemicyanine class of chromophores. Strategic placement of the fluorine atoms on the chromophores can result in either blue or red shifts in the absorbance and emission spectra. The range of one-photon excitation wavelengths afforded by these new VSDs spans 440–670 nm; the two-photon excitation range is 900–1,340 nm. The emission of each VSD is shifted by at least 100 nm to the red of its one-photon excitation spectrum. The set of VSDs, thus, affords an extended toolkit for optical recording to match a broad range of experimental requirements. We show the sensitivity to voltage and the photostability of the new VSDs in a series of experimental preparations ranging in scale from single dendritic spines to whole heart. Among the advances shown in these applications are simultaneous recording of voltage and calcium in single dendritic spines and optical electrophysiology recordings using two-photon excitation above 1,100 nm.
Optogenetically induced sleep spindle rhythms alter sleep architectures in mice
Authors: Kim Angela , Latchoumane Charles , Lee Soojung , Kim Guk Bae , Cheong Eunji , Augustine George J. , Shin Hee-Sup
Published: November 2012

Sleep spindles are rhythmic patterns of neuronal activity generated within the thalamocortical circuit. Although spindles have been hypothesized to protect sleep by reducing the influence of external stimuli, it remains to be confirmed experimentally whether there is a direct relationship between sleep spindles and the stability of sleep. We have addressed this issue by using in vivo photostimulation of the thalamic reticular nucleus of mice to generate spindle oscillations that are structurally and functionally similar to spontaneous sleep spindles. Such optogenetic generation of sleep spindles increased the duration of non-rapid eye movement (NREM) sleep. Furthermore, the density of sleep spindles was correlated with the amount of NREM sleep. These findings establish a causal relationship between sleep spindles and the stability of NREM sleep, strongly supporting a role for the thalamocortical circuit in sleep regulation.
Mutual protection of ribosomal proteins L5 and L11 from degradation is essential for p53 activation upon ribosomal biogenesis stress
Authors: Bursać Sladana , Brdovčak Maja Cokarić , Pfannkuchen Martin , Orsolić Ines , Golomb Lior , Zhu Yan , Katz Chen , Daftuar Lilyn , Grabušić Kristina , Vukelić Iva , Filić Vedrana , Oren Moshe , Prives Carol , Volarević Siniša
Published: November 2012

Impairment of ribosomal biogenesis can activate the p53 protein independently of DNA damage. The ability of ribosomal proteins L5, L11, L23, L26, or S7 to bind Mdm2 and inhibit its ubiquitin ligase activity has been suggested as a critical step in p53 activation under these conditions. Here, we report that L5 and L11 are particularly important for this response. Whereas several other newly synthesized ribosomal proteins are degraded by proteasomes upon inhibition of Pol I activity by actinomycin D, L5 and L11 accumulate in the ribosome-free fraction where they bind to Mdm2. This selective accumulation of free L5 and L11 is due to their mutual protection from proteasomal degradation. Furthermore, the endogenous, newly synthesized L5 and L11 continue to be imported into nucleoli even after nucleolar disruption and colocalize with Mdm2, p53, and promyelocytic leukemia protein. This suggests that the disrupted nucleoli may provide a platform for L5- and L11-dependent p53 activation, implying a role for the nucleolus in p53 activation by ribosomal biogenesis stress. These findings may have important implications with respect to understanding the pathogenesis of diseases caused by impaired ribosome biogenesis.
A first glance at the role of length in production and perception of diphthongs before Dutch coda l
Authors: Berns Janine , Jacobs Haike
Published: November 2012

Botma, Sebregts & Smakman (2008, 2010, 2012) have shown that in Dutch there is variation in the neutralization of tense and lax vowels before coda l. In this study, we will extend the scope of their investigation by examining the effect of coda l on preceding diphthongs. A pilot production experiment shows that diphthongs can be completely neutralized in this context and may become monophthongs. A perception experiment reveals that length serves as an important cue for listeners in the identification of vowels followed by dark l.
The centrality of thematic relations in Japanese text
Authors: Maynard Senko K.
Published: November 2012

This paper examines three ways in which thematic relations are realized in Japanese text. Scholars in the past have focused on limited cases of thematization in Japanese — mostly realized by the thematic particle wa from the given-new information perspective. Following and advancing this tradition, in this paper I analyze three cases of thematic relations; (1) the staging effect realized by thematization and non-thematization in narrative discourse, (2) the expressive effect of the nominal predicate n(o) da which possesses thematic structural properties, and (3) the poetic effect of thematic suspension realized by thematic (interrogative) clauses. I emphasize that thematization is a phenomenon which pervades every aspect of the Japanese language. The three types of thematic relations explored in this study — although constituting only the tip of the iceberg — provide evidence for the claim that the nature of the Japanese language is theme-centered in contrast to the subject-predicate-prominent nature of Indo-European languages.
Finnish writers' academic English
Authors: Ventola Eija
Published: November 2012

The paper illustrates how many Finnish writers tend to have difficulties coding references to text participants appropriately in their English texts. When organising their texts thematically, Finnish writers also appear to apply thematic patterns which are not typical of English texts. In addition, Finnish writers do not seem to utilise the possibilities of the interplay between the REFERENCE and THEME systems at their textual optimum. The insights into the textual analysis of FL-scientific writing presented here may prove useful when applied linguists are facing the challenge of designing courses for academic writing in a foreign language, courses which will develop learners' consciousness and linguistic skills in organising information in texts in a way which is referentially and thematically cohesive.
Wait a second: Brief delays in responding reduce focality effects in event-based prospective memory
Authors: Loft Shayne , Remington Roger W.
Published: November 2012

Remembering to perform deferred actions when an event is encountered in the future is referred to as event-based prospective memory (PM). We examined whether the failure of individuals to allocate sufficient attentional resources to nonfocal PM tasks can be linked to the response demands inherent in PM paradigms that require the PM task to race for response selection with the speeded ongoing task. In three experiments, participants performed a lexical decision task while being required to make a separate PM response to a specific word (focal), an exemplar of a category (nonfocal), or a syllable (nonfocal). We manipulated the earliest time participants could make task responses by presenting a tone at varying onsets (0–1,600 ms) following stimulus presentation. Improvements in focal PM and nonfocal PM were observed at response delays as brief as 200 ms and 400 ms, respectively. Nonfocal PM accuracy was comparable to focal PM accuracy at delays of 600 ms and 1,600 ms for categorical targets and syllable targets, respectively. Delaying task responses freed the resource-demanding processing operations used on the ongoing task for use on the nonfocal PM task, increasing the probability that the nonfocal PM features of ongoing task stimuli were adequately assessed prior to the ongoing task response.
Almost Souslin Kurepa trees
Authors: Golshani Mohammad
Published: November 2012

We show that the existence of an almost Souslin Kurepa tree is consistent with

Z
F
C

ZFC

. We also prove their existence in

L
L

. These results answer two questions from a paper by Zakrzewski.
Isometric immersions of warped products
Authors: Dajczer Marcos , Vlachos Theodoros
Published: November 2012

We provide conditions under which an isometric immersion of a (warped) product of manifolds into a space form must be a (warped) product of isometric immersions.
Underwater radiated noise measurements of a noise-reduced fisheries research vessel
Authors: De Robertis Alex , Wilson Christopher D. , Furnish Scott R. , Dahl Peter H.
Published: November 2012

De Robertis, A., Wilson, C. D., Furnish, S. R., and Dahl, P. H. 2013. Underwater radiated noise measurements of a noise-reduced fisheries research vessel. – ICES Journal of Marine Science, 70: 480–484. Vessel-radiated noise is traditionally measured at naval acoustic ranges, but lower-cost options are desirable for routine monitoring of research vessels. Measurements of a noise-reduced research vessel made at a naval noise range are compared to those made using an experimental mooring equipped with commercially available instrumentation. The measurements from the mooring were precise and within 2.5 dB of those from the noise range at third-octave bands <500 Hz. At higher frequencies, direct comparisons were precluded by an intermittent shaft-related noise present only during the mooring measurements, but previously observed at the navy range. The agreement between the two methods suggests that simplified, field-deployable hydrophone systems can be used to accurately characterize the noise signatures of research vessels.
Lower Extremity Predominant Stiff-Person Syndrome and Limbic Encephalitis With Amphiphysin Antibodies in Breast Cancer
Authors: Krishna Vivek R. , Knievel Kerry , Ladha Shafeeq , Sivakumar Kumaraswamy
Published: November 2012

A 54-year-old woman presented with several weeks of psychiatric symptoms, partial-onset seizures, and painful spasms of the lower extremities. On examination, she exhibited severe stiffness and intermittent extensor spasms of the lower extremities. Magnetic resonance imaging of the brain showed T2 hyperintensity in the left temporal lobe with enhancement after gadolinium administration on T1-weighted images. Amphiphysin antibodies were present in the serum. Radiographic screening for malignancy disclosed a metastatic breast cancer. The case is a unique example of amphiphysin autoimmunity, illustrating the possibility of paraneoplastic stiff-person syndrome and limbic encephalitis coexisting in a patient with a “classical” presentation of stiff-person syndrome confined to the lower extremities.
Colour misbinding during motion rivalry
Authors: Maloney Ryan T. , Lam Sarah K. , Clifford Colin W. G.
Published: November 2012

When two dissimilar colours are displayed to the two eyes at overlapping retinal locations, binocular rivalry typically results: a fluctuating struggle for perceptual dominance of each eye's stimulus. We found instead that isoluminant counter-rotating patterns consisting of coloured and achromatic portions can promote an illusory colour ‘misbinding’, where the colours from both eyes were perceived within a single rotating pattern. The achromatic portion of one rotating pattern thus appeared to take on the colour of the other, oppositely rotating pattern. The results suggest that the neural mechanisms of colour binding can operate even while representations of the same patterns' motions are undergoing rivalry, and support the idea that rivalry can occur in isolation within the motion system.
Dissecting a wildlife disease hotspot: the impact of multiple host species, environmental transmission and seasonality in migration, breeding and mortality
Authors: Brown V. L. , Drake J. M. , Stallknecht D. E. , Brown J. D. , Pedersen K. , Rohani P.
Published: November 2012

Avian influenza viruses (AIVs) have been implicated in all human influenza pandemics in recent history. Despite this, surprisingly little is known about the mechanisms underlying the maintenance and spread of these viruses in their natural bird reservoirs. Surveillance has identified an AIV ‘hotspot’ in shorebirds at Delaware Bay, in which prevalence is estimated to exceed other monitored sites by an order of magnitude. To better understand the factors that create an AIV hotspot, we developed and parametrized a mechanistic transmission model to study the simultaneous epizootiological impacts of multi-species transmission, seasonal breeding, host migration and mixed transmission routes. We scrutinized our model to examine the potential for an AIV hotspot to serve as a ‘gateway’ for the spread of novel viruses into North America. Our findings identify the conditions under which a novel influenza virus, if introduced into the system, could successfully invade and proliferate.