bluuebunny/crossref_metadata_2025 huggingface dataset:
Memory diodes with nonzero crossing
Authors: Saraf Shimon , Markovich Miri , Vincent Tracey , Rechter Roman , Rothschild Avner
Published: January 2013

Memristors combine switching, memory, and rectification functions in two-terminal nanoelectronic devices. The theory says that their current-voltage (I-V) characteristics cross over at the zero crossing point (I = V = 0), and the results reported hitherto conform to this theorem. Here, we extend the family of memristive devices, adding memory diodes (memdiodes) comprising SrTiO3 pn junctions that display unique combination of rectification, hysteresis, and nonzero crossing. Reverse bias polarization gives rise to a nonzero open circuit voltage that persists after the junction is disconnected from the external circuit. This opens up an opportunity for a new type of nonvolatile memories.
Improved luminescence from CdSe quantum dots with a strain-compensated shell
Authors: Lu Y. , Zhang Y. Q. , Cao X. A.
Published: January 2013

Colloidal CdSe quantum dots (QDs) with a strain-compensated ZnS/ZnCdS bilayer shell were synthesized and characterized. The core/shell/shell structure enjoys the benefits of excellent exciton confinement by the ZnS intermediate shell and strain compensation by the ZnCdS outer shell. The resulting CdSe/ZnS/ZnCdS QDs exhibited a 40% higher photoluminescence quantum yield and a more controllable wavelength compared to conventional CdSe/ZnCdS/ZnS core/shell/shell QDs with an intermediate lattice adaptor. CdSe/ZnS/ZnCdS QD light-emitting diodes (LEDs) had a luminance of 556 cd/m2 at 20 mA/cm2, 28% higher than that of CdSe/ZnCdS/ZnS QD-LEDs. The former also had better spectral purity at high injection currents and are thus better suited for full-color displays.
Cross sections of operating Cu(In,Ga)Se2 thin-film solar cells under defined white light illumination analyzed by Kelvin probe force microscopy
Authors: Zhang Zhenhao , Hetterich Michael , Lemmer Uli , Powalla Michael , Hölscher Hendrik
Published: January 2013

The contact potential of cross sections of operating Cu(In,Ga)Se2 thin-film solar cells is analyzed by Kelvin probe force microscopy under defined illumination intensities with white light. The potential drop through the solar cell heterojunction is found to decrease with increasing illumination intensity up to flat-band conditions and the decrease of the potential drop correlates with the increase of the photovoltage induced by the illumination. Interestingly, we observe that potential variations at Cu(In,Ga)Se2 grain boundaries decrease to less than 50 mV under illumination. With this finding, the often claimed beneficial effect of Cu(In,Ga)Se2 grain boundaries is critically discussed.
How does external feedback cause AlGaAs-based diode lasers to degrade?
Authors: Hempel Martin , Chi Mingjun , Petersen Paul M. , Zeimer Ute , Tomm Jens W.
Published: January 2013

The effect of external feedback on the degradation of 808 nm emitting AlGaAs-based high-power broad-area diode lasers is studied. For this purpose, early stages of gradual degradation are induced by accelerated aging at high power levels. While the quantum well that actually experiences the highest total optical load remains unaffected, severe impact by point defects is observed on the cladding layers and the waveguide. Extended defects such as dislocations, however, are not observed in such early stages of degradation, which are accompanied by gradual power loss of a few percent only.
Bistable springs for wideband microelectromechanical energy harvesters
Authors: Nguyen Son D. , Halvorsen Einar , Paprotny Igor
Published: January 2013

This paper presents experimental results on a microelectromechanical energy harvester with curved springs that demonstrates an extremely wide bandwidth. The springs display an asymmetrical bistable behavior obtained purely through their geometrical design. The frequency down-sweep shows that the harvester 3-dB bandwidth is about 587 Hz at 0.208-g acceleration amplitude. For white noise excitation at 4×10−3 g2/Hz, we found that the bandwidth reaches 715 Hz, which is more than 250 times wider than in the linear-spring regime. By varying the bias voltage, an output power of 3.4 μW is obtained for frequency down-sweep at 1-g amplitude and 150-V bias.
Improving dielectric properties of epitaxial Gd2O3 thin films on silicon by nitrogen doping
Authors: Roy Chaudhuri Ayan , Fissel A. , Archakam V. R. , Osten H. J.
Published: January 2013

We report about the effect of nitrogen doping on the electrical properties of epitaxial Gd2O3 thin films. Epitaxial Gd2O3:N thin films were grown on Si (111) substrates by solid source molecular beam epitaxy using nitrous oxide as the nitridation agent. Substitutional nitrogen incorporation into the dielectric layer was confirmed by secondary ion mass spectroscopy and X-ray photoelectron spectroscopy analysis. Substantial reduction of the leakage current density and disappearance of hysteresis in capacitance-voltage characteristics observed in the Gd2O3:N layers indicate that nitrogen incorporation in Gd2O3 effectively eliminates the adverse effects of the oxygen vacancy induced defects in the oxide layer.
Giant low field magnetocaloric effect in soft ferromagnetic ErRuSi
Authors: Gupta Sachin B. , Suresh K. G.
Published: January 2013

The magnetic and magnetocaloric properties of the intermetallic compound ErRuSi have been investigated. The compound shows ferromagnetic ordering with Curie temperature of 8 K. The magnetic transition is found to be first order in nature. The maximum entropy change and refrigerant capacity are found to be 21.2 J/kg K and 416 J/kg for a field change of 50 kOe. The low field (20 kOe) entropy change is also found to be quite large (15.2 J/kg K). Additionally, the compound shows very little thermal and field hysteresis, fulfilling the required condition for a good magnetic refrigerant in the low temperature regime.
Temperature dependence of the direct bandgap and transport properties of CdO
Authors: Vasheghani Farahani S. K. , Muñoz-Sanjosé V. , Zúñiga-Pérez J. , McConville C. F. , Veal T. D.
Published: January 2013

Temperature-dependent optical absorption, Hall effect, and infrared reflectance measurements have been performed on as-grown and post-growth annealed CdO films grown by metal organic vapor phase epitaxy on sapphire substrates. The evolution of the absorption edge and conduction electron plasmon energy with temperature has been modeled, including the effects arising from the Burstein-Moss shift and bandgap renormalization. The zero-temperature fundamental direct bandgap and band edge effective mass have been determined to be 2.31 ± 0.02 eV and 0.27±0.01m0, respectively. The associated Varshni parameters for the temperature dependence of the bandgap are found to be α=8×10−4 eV/K and β=260 K.
Nanosecond voltage pulses from dendritic flux avalanches in superconducting NbN films
Authors: Mikheenko P. , Qviller A. J. , Vestgården J. I. , Chaudhuri S. , Maasilta I. J. , Galperin Y. M. , Johansen T. H.
Published: January 2013

Combined voltage and magneto-optical study of magnetic flux flow in superconducting NbN films is reported. The nanosecond-scale voltage pulses appearing during thermomagnetic avalanches have been recorded in films partially coated by a metal layer. Simultaneous magneto-optical imaging and voltage measurements allowed the pulses to be associated with individual flux branches penetrating the superconductor below the metal coating. From detailed characteristics of pulse and flux branches, the electrical field in the superconductor is found to be in the range of 5-50 kV/m, while the propagation speed of the avalanche during its final stage is found to be close to 5 km/s.
Hybrid density functional study of electronic and optical properties of phase change memory material: Ge2Sb2Te5
Authors: Kaewmaraya T. , Ramzan M. , Löfås H. , Ahuja Rajeev
Published: January 2013

In this article, we use hybrid density functional (HSE06) to study the crystal and electronic structures and optical properties of well known phase change memory material Ge2Sb2Te5. We calculate the structural parameters, band gaps, and dielectric functions of three stable structures of this material. We also analyze the electron charge distribution using the Bader's theory of charge analysis. We find that hybrid density functional slightly overestimates the value of “c” parameter. However, overall, our results calculated with the use of hybrid density functional (HSE06) are very close to available experimental values than calculated with the use of Perdew Burke-Ernzerhof functional. Specifically, the electronic band gap values of this material calculated with HSE06 are in good agreement with the available experimental data in the literature. Furthermore, we perform the charge analysis and find that naive ionic model fails to explain the charge distribution between the constituent atoms, showing the complex nature of this compound.
Pressure effect on ZnO nanoparticles prepared via laser ablation in water
Authors: Kulinich S. A. , Kondo Takahiro , Shimizu Yoshiki , Ito Tsuyohito
Published: January 2013

ZnO nanoparticles were prepared via laser ablation of metallic Zn in neat deionized water at pressures up to ∼31 MPa and at constant ablation time, fluence, and wavelength. The high-pressure products were compared with those prepared at 1 atm, and the effect of water pressure on the product size and photoluminescent properties was studied. The results indicate that the use of pressure permits to control the particle size, the position of their exciton emission peak, and the intensity of their visible emission. While smaller and more homogeneous in size ZnO particles were produced at elevated pressures, their UV emission peak blue-shifted and green emission was enhanced. At pressures ∼22 MPa, a discontinuity in the improvement of the product green emission was observed, which should be related to the appearance of supercritical water in the ablated zone.
N incorporation in GaInNSb alloys and lattice matching to GaSb
Authors: Ashwin M. J. , Walker D. , Thomas P. A. , Jones T. S. , Veal T. D.
Published: January 2013

The incorporation of N into MBE grown GaNSb and GaInNSb is investigated. Measurements of the N fraction in GaNSb show the familiar linear dependence on inverse growth rate, followed by a departure from this at low growth rates; a similar behaviour is observed for GaInNSb. Unexpectedly, the point at which there is a departure from this linear behaviour is found to be extended to lower growth rates by the addition of small amounts of In. These results are compared to a kinetic theory-based model from which it is postulated that the change in behaviour can be attributed to an In-induced change in the characteristic surface residence lifetime of the N atoms. In addition, a method is demonstrated for growing GaInNSb lattice-matched to GaSb(001) for compositions with band gaps covering the 2–5 μm region.
Planar defects, dislocations, and coherently scattering-size in GdBa2Cu3O7−x high-Tc thin films determined by high resolution X-ray diffraction
Authors: Csiszár Gábor , Li Xiao-Fen , Zilahi Gyula , Balogh Levente , Ungár Tamás
Published: January 2013

The frequency of planar defects, the average dislocation densities, and coherent domain size in epitaxial GdBa2Cu3O7−x high Tc thin films, with altering CuO2 and CuO planes, are measured by fitting full widths at half maximum values of 00l type reflections using a model function based on intensity distribution configurations in reciprocal space. The reduction of the dislocation density during oxygenation seems to be an unavoidable condition to obtain superconductivity in GdBa2Cu3O7−x thin films.
Topological field theory of dynamical systems. II
Authors: Ovchinnikov Igor V.
Published: January 2013

This paper is a continuation of the study [Chaos.22.033134] of the relation between the stochastic dynamical systems (DS) and the Witten-type topological field theories (TFT). Here, it is discussed that the stochastic expectation values of a DS must be complemented on the TFT side by (−1)F̂, where F̂ is the ghost number operator. The role of this inclusion is to unfold the natural path-integral representation of the TFT, i.e., the Witten index that equals up to a topological constant to the partition function of the stochastic noise, into the physical partition function of TFT/DS. It is also shown that on the DS side, the TFT's wavefunctions are the conditional probability densities.
The estimation of neurotransmitter release probability in feedforward neuronal network based on adaptive synchronization
Authors: Xue Ming , Wang Jiang , Jia Chenhui , Yu Haitao , Deng Bin , Wei Xile , Che Yanqiu
Published: January 2013

In this paper, we proposed a new approach to estimate unknown parameters and topology of a neuronal network based on the adaptive synchronization control scheme. A virtual neuronal network is constructed as an observer to track the membrane potential of the corresponding neurons in the original network. When they achieve synchronization, the unknown parameters and topology of the original network are obtained. The method is applied to estimate the real-time status of the connection in the feedforward network and the neurotransmitter release probability of unreliable synapses is obtained by statistic computation. Numerical simulations are also performed to demonstrate the effectiveness of the proposed adaptive controller. The obtained results may have important implications in system identification in neural science.
Microscopic magnetic structuring of a spin-wave waveguide by ion implantation in a Ni81Fe19 layer
Authors: Obry Björn , Meyer Thomas , Pirro Philipp , Brächer Thomas , Lägel Bert , Osten Julia , Strache Thomas , Fassbender Jürgen , Hillebrands Burkard
Published: January 2013

We investigate the spin-wave excitation in microscopic waveguides fabricated by localized Cr+ ion implantation in a ferromagnetic Ni81Fe19 film. We demonstrate that spin-wave waveguides can be conveniently made by this technique. The magnetic patterning technique yields an increased damping and a reduction in saturation magnetization in the implanted regions that can be extracted from Brillouin light scattering measurements of the spin-wave excitation spectra. Furthermore, the waveguide performance as well as the internal field of the waveguide depend on the doping fluence. The results prove that localized ion implantation is a powerful tool for the patterning of magnon spintronic devices.
Fabrication of stereo metallic resonant structures with polymer droplets as template
Authors: Chen Xiao-Chun , Wu Yuan-Wei , Hu Yu-Hui , Li Hong-Min , Peng Ru-Wen , Hao Xi-Ping , Wang Mu
Published: January 2013

Using polymer droplets formed in dewetting of polymer film on silicon surface as template, the silicon columns capped with circular polymer plates are fabricated via plasma etching. By blanket deposition of a gold layer on the structure, an array of metallic microcavities featured by a metal circular plate separated by a silicon column with the bottom metallic film is achieved. The geometrical parameters of the stereo structures can be tuned. We show that the electric field at the edge of the cap is greatly enhanced, which can be used as the hot spot for trace amount of chemical detection.
Temperature dependent carrier dynamics in telecommunication band InAs quantum dots and dashes grown on InP substrates
Authors: Jahan Nahid A. , Hermannstädter Claus , Huh Jae-Hoon , Sasakura Hirotaka , Rotter Thomas J. , Ahirwar Pankaj , Balakrishnan Ganesh , Akahane Kouichi , Sasaki Masahide , Kumano Hidekazu , Suemune Ikuo
Published: January 2013

InAs quantum dots (QDs) grown on InP substrates can be used as light emitters in the telecommunication bands. In this paper, we present optical characterization of high-density circular quantum dots (QDots) grown on InP(311)B substrates and elongated dots (QDashes) grown on InP(001) substrates. We study the charge carrier transfer and luminescence thermal quenching mechanisms of the QDots and QDashes by investigating the temperature dependence of their time-integrated and time-resolved photoluminescence properties. This results in two different contributions of the thermal activation energies. The larger activation energies are attributed to the carrier escape to the barrier layer and the wetting layer (WL) from QDots and QDashes, respectively. The smaller activation energies are found to be originated from inter-dot/dash carrier transfer via coupled excited states. The variation of the average oscillator strength associated with the carrier re-distribution is discussed. The relation of the two activation energies is also quantitatively studied with the measurements of excited-state and ground-state energy separations. Finally, we show an approach to isolate individual quantum dots or dashes in a suitable nanostructure.
Sample length independent conduction current in polyethylene oxide
Authors: Martin Bjoern , Kliem Herbert
Published: January 2013

The transient current density through ion conducting polyethylene oxide samples of different lengths is measured after application of voltage steps with different amplitudes. In the experiments, it is found that at a given voltage step the long-term current density is independent of the sample length. Qualitatively, the same behavior is attained from computer simulations using a three-dimensional hopping model which takes into account internal ionic charge movements and extrinsic electronic charge injection from the electrodes. It turns out that the width of a depletion zone of mobile ions at the electrode, which only depends on the applied voltage, is responsible for the independence of the current from the sample length.
Control of field-effect transistor threshold voltages by insertion of self-assembled monolayers
Authors: Ojima T. , Koto M. , Itoh M. , Imamura T.
Published: January 2013

We report the control of the threshold voltage of field-effect-transistors (FET) by inserting a self-assembled monolayer (SAM) between the insulator and the gate electrode. The surface potentials of the SAMs, measured by Kelvin force microscopy, depended on the dipole moments of their monomer units. The SAMs were formed by chemical vapor deposition at low temperatures from various monomer units with different dipole moments. The dipole moments were determined by ab initio calculations. The FET properties, such as the threshold voltage, could be controlled by SAMs inserted between the insulator and the gate electrode. The threshold voltage shift was linearly correlated with the surface potential of the SAM. The transconductance also depended on the dipole moment of the SAM monomer unit. Therefore, altering the transconductance could also increase the range of the threshold voltage. The use of SAMs provides a simple method for controlling the properties of transistors, and can be used in thin film transistors, such as organic and oxide devices.
Strong electron and ion emissions induced by a pyroelectric crystal
Authors: Hockley M. , Huang Z.
Published: January 2013

A novel method of high voltage pulse generation was developed, based on charging a capacitor by changing the temperature of a pyroelectric crystal. A high voltage pulse is formed when a miniature spark gap device in connection with the charging capacitor is suddenly switched on. This high voltage pulse is then used to trigger strong electron and ion emissions from a ferroelectric cathode. The developments of voltage and emission with time were compared with those when the voltage pulse was produced by an external power source, and the differences were explained as due to different electric boundary conditions, based on the surface plasma assisted emission mechanisms. Factors affecting the ferroelectric cathode emissions, such as the capacitance of the charging capacitor, the polarity of the voltage pulses being applied to the front or rear electrode of the cathode, and the shape of the front grid electrode, have been investigated. Significantly higher current and total emitted electrons were observed in the case of a negative voltage applied to the front electrode. Other emission features such as the energy of the emitted particles and density distribution were also characterised.
Overlap of the intrinsic and extrinsic magnetoelectric effects in BiFeO3-PbTiO3 compounds: Potentialities for magnetic-sensing applications
Authors: Montanher D. Z. , Freitas V. F. , Pereira J. R. D. , Cótica L. F. , Garcia D. , Eiras J. A. , Santos I. A.
Published: January 2013

The potentialities of BiFeO3-PbTiO3 multiferroic compounds for magnetic-field sensing applications is investigated by characterizing the dynamical magnetoelectric response of La doped (0.6)BiFeO3-(0.4)PbTiO3 piezoceramics. The results are compared with those obtained in Nb doped (1 wt. %) PbZr0.53Ti0.47O3 (PZT-5A) piezoceramics and the observed non-linearity of the oscillating voltage response of (0.6)BiFeO3-(0.4)PbTiO3 piezoceramics is attributed to the overlapping of the intrinsic and extrinsic magnetoelectric effects that were successfully decoupled by analyzing the in-phase and out-of-phase voltage components relative to applied oscillating magnetic field. For an alternating cosine-like magnetic field of 0.32 Oe, at the piezoelectric resonance frequency (184.2 kHz), the alternating voltage response decreases from 7.77 mV, at −10 kOe, to 2.71 mV, at 1.8 kOe, to subsequently increases until 5.97 mV at 10 kOe. This non-linear voltage response, which can be easily converted into a linear signal by using the phase difference, can be used for static magnetic field sensing in a wide range of magnetic fields.
Processing optimization and sintering time dependent magnetic and optical behaviors of Aurivillius Bi5Ti3FeO15 ceramics
Authors: Chen Guang , Bai Wei , Sun Lin , Wu Jing , Ren Qing , Xu Wenfei , Yang Jing , Meng Xiangjian , Tang Xiaodong , Duan Chun-Gang , Chu Junhao
Published: January 2013

Aurivillius Bi5Ti3FeO15 (BTF) ceramics were synthesized using the conventional solid state reaction method by optimizing excess of Bi2O3 and sintering time. Their structures, magnetic, and optical properties were investigated in detail. The optimum process to sinter pure Aurivillius BTF ceramics was confirmed to be 3 wt. % excess Bi2O3 to compensate the Bi volatilization at 1050 °C for 240 min (BTF-240M). The microstructure and crystalline structure of the BTF ceramics had little dependence on the sintering time from the x-ray diffraction (XRD) and scanning electron microscopic data. Nevertheless, the magnetic and optical properties were closely related with the sintering time. The overall magnetic behavior of these BTF ceramics was superparamagnetic (SPM), whereas there were unambiguous clues for the existence of antiferromagnetic (AFM) interactions. However, whether the SPM behavior was intrinsic or arised from a tiny amount of spinel Fe3O4 impurity phase cannot be thoroughly ruled out in the XRD detection limit in the present stage. The AFM interactions were weakened upon extending the sintering time. The effective magnetic moment (μeff), however, demonstrated different dependency on the sintering time. It increased with the sintering time from 80 min to 240 min, and then dropped with further extending the sintering time. Compared with other BTF ceramics, the BTF-240M ceramic showed the highest values of the refractive index n and real part ε1, as well as the lowest ones of the extinction coefficient k and imagine part ε2 in whole photon energy range. Finally, a direct inter-band transition was confirmed for these BTF ceramics and optical energy band gaps were determined to be about 3.08, 3.18, and 3.39 eV for 80 min, 150 min, and 240 min sintered BTF ceramics, respectively, yet abnormal optical behavior was observed in BTF-360M ceramic.
Formation and optical absorption property of nanometer metallic colloids in Zn and Ag dually implanted silica: Synthesis of the modified Ag nanoparticles
Authors: Wang Jun , Jia Guangyi , Zhang Bei , Liu Huixian , Liu Changlong
Published: January 2013

Nanometer metallic colloids in silica glasses were fabricated by dual implantation of Zn and Ag ions in different implantation sequences. In the case of Zn ions followed by Ag ions, Ag nanoparticles (NPs) were formed, which had small size, narrow size distribution and high volume fraction, as well as modified dielectric environment. As a result, the Zn first and then Ag implanted samples presented an intense absorption peak around 435 nm, which was much stronger than that at about 406 nm detected in the Ag singly implanted specimen at the same Ag ion fluence. Variation of Zn ion fluence only gave rise to slight change of the absorption signal. In contrast, a dual implantation of Ag first and then Zn ions resulted in formation of Ag, Zn, and Ag–Zn alloy NPs, consequently inducing a weak and broad absorption band lying between those related to monometallic Ag and Zn NPs. The underlying mechanisms for the above findings were discussed. Especially, an enhanced deposition process of Ag implants caused by the prior Zn implantation was proposed.
Effects of quasicrystal formation on the crystallization of (Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17) metallic glasses
Authors: Sha P. F. , Zhu Z. W. , Tang M. Q. , Fu H. M. , Li Z. K. , Li H. , Wang A. M. , Zhang H. W. , Zhang H. F. , Hu Z. Q.
Published: January 2013

The crystallization behaviors of the (Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17; at. %) metallic glasses are investigated under both the continuous heating and isothermal conditions by the differential scanning calorimetry. Quasicrystals are found in the crystallization products under both conditions by X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The evolution of the primary crystallization products of these alloys is discussed in detail. The effects of the increasing distortion energy of the icosahedral short-range order with the increasing Cu content in the(Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17) alloys are found to be responsible for the evolution of the crystallization products. The isothermal crystallization kinetics deviates from the Johnson-Mehl-Avrami-Kolmogoroff (JMAK) model. A modified JMAK model with an impingement parameter is found to be suitable for the isothermal crystallization kinetics of the current alloys. The effects of quasicrystal formation on the crystallization kinetics are disscussed in detail. And it is found that the isothermal crystallization kinetics are influenced by both of the “soft impingement” effect and the formation of the quasicrystals.
Surface enhanced fluorescence and Raman scattering by gold nanoparticle dimers and trimers
Authors: Zhang Zhenglong , Yang Pengfei , Xu Hongxing , Zheng Hairong
Published: January 2013

Dimers and trimers of gold nanoparticles were synthesized using wet chemistry method for surface enhanced fluorescence and Raman scattering. The dimers and trimers provide hot spots for enhancing the fluorescence and Raman signals, and significantly obvious enhancement is obtained from Raman signals in solution. Using finite element method, we calculate the enhancement of fluorescence and Raman signals in the experimental system. Both experimental and theoretical results show that the dimers and trimers solution can be used in micro-quantitative detection from fluorescence and Raman signals.
The silicon Schottky diode on flexible substrates by transfer method
Authors: Oh Tae-Yeon , Woo Jeong Shin , Chang Seongpil , Choi Kookhyun , Jun Ha Hyun , Kwon Ju Byeong
Published: January 2013

A flexible silicon barrier diode was fabricated by the transfer printing method. Micro-line patterned p-type single crystalline silicon membranes were created from a silicon on insulator wafer. The dark current of our device was very low, about 1 pA for reverse bias voltages up to 5 V, and showed rectifying behavior with an ideality factor of 1.05. The photo-response and the responsivity was 32 and 0.3 A/W, respectively, for light intensity of 1.2 mW/cm2. Also, the current of the photodetector changed under compressive stress or tensile stress. Our device is functional as the piezotronic sensor as well as the photodetector.
Nonlocal electro-optic effects for transverse electric modes in quantum well Mach-Zehnder modulators
Authors: Wang Guanghui , Wang Ruiqiang
Published: January 2013

We develop a microscopic nonlocal theory for the electro-optic effect (Pockels effect) and report its effective electrorefractive modulation for transverse electric (TE) waves in a quantum well (QW) waveguide Mach-Zehnder modulator. A general expression for the dielectric function with spatial dispersion for TE modes is derived. Furthermore, it is desirable that a low absorption loss (α<9.0 cm−1) and a large refractive index change (Δn∼0.00137) are obtained by an optimal bias electric field and QW width. These properties may have extensive applications in the field of optoelectronics.
Linear analysis of time dependent properties of Child-Langmuir flow
Authors: Rokhlenko A.
Published: January 2013

We continue our analysis of the time dependent behavior of the electron flow in the Child-Langmuir system, removing an approximation used earlier. We find a modified set of oscillatory decaying modes with frequencies of the same order as the inverse of the electron transient time. This range (typically MHz) allows simple experimental detection and maybe exploitation. We then study the time evolution of the current in response to a slow change of the anode voltage where the same modes of oscillations appear too. The cathode current in this case is systematically advanced or retarded depending on the direction of the voltage change.
On the residual stress and fracture strength of crystalline silicon wafers
Authors: Yang Chris , Mess Frank , Skenes Kevin , Melkote Shreyes , Danyluk Steven
Published: January 2013

This letter reports on residual stress measurement in thin crystalline silicon wafers with a full-field near-infrared polariscope. Residual stress is analyzed in combination with observed surface defects, and the results are related to measured fracture strength variation in the wafers. Measurements indicate that there is a sawing process-related residual stress in the as-cut wafers, and that etch-removal of ∼5 μm from the wafer surface eliminates a damage layer that can significantly reduce the residual stress in the wafer, and therefore increases the observed fracture strength. There is a corresponding 2 to 3 μm reduction in the observed characteristic defect size after etching. Fracture strength anisotropy observed in the wafers is related to defect orientation (scratching grooves and microcracks) caused by the sawing process.
Magnetization reversal in Nd-Fe-B based nanocomposites as seen by magnetic small-angle neutron scattering
Authors: Bick Jens-Peter , Honecker Dirk , Döbrich Frank , Suzuki Kiyonori , Gilbert Elliot P. , Frielinghaus Henrich , Kohlbrecher Joachim , Gavilano Jorge , Forgan Edward M. , Schweins Ralf , Lindner Peter , Birringer Rainer , Michels Andreas
Published: January 2013

We have studied the magnetization-reversal process of a Nd2Fe14B/Fe3B nanocomposite using small-angle neutron scattering. Based on the computation of the autocorrelation function of the spin misalignment, we have estimated the characteristic size lC of spin inhomogeneities around the Nd2Fe14B nanoparticles. The quantity lC approaches a constant value of about 12.5 nm (∼average Nd2Fe14B particle radius) at 14 T and takes on a maximum value of about 18.5 nm at the coercive field of −0.55 T. The field dependence of lC can be described by a model that takes into account the convolution relationship between the nuclear and the magnetic microstructure.
Substrate orientation dependence on the solid phase epitaxial growth rate of Ge
Authors: Darby B. L. , Yates B. R. , Martin-Bragado I. , Gomez-Selles J. L. , Elliman R. G. , Jones K. S.
Published: January 2013

The solid phase epitaxial growth process has been studied at 330 °C by transmission electron microscopy for Ge wafers polished at 10°–15° increments from the [001] to [011] orientations. The velocity showed a strong dependence on substrate orientation with the [001] direction displaying a velocity 16 times greater than the [111] direction. A lattice kinetic Monte Carlo model was used to simulate solid phase epitaxial growth (SPEG) rates at different orientations, and simulations compared well with experimental results. Cross sectional transmission electron microscopy and plan view transmission electron microscopy revealed stacking fault and twin defect formation in the [111] orientation where all other orientations showed only hairpin dislocations. The twin defects formed from Ge SPEG were comparatively less dense than what has previously been reported for Si, which gave rise to higher normalized velocities and a constant [111] SPEG velocity for Ge.
Operation of transition edge sensors in a resistance locked loop
Authors: van der Kuur J. , Kiviranta M.
Published: January 2013

We propose to operate a superconducting transition edge sensor (TES) using a different type of biasing, in which the resistance of the TES is kept constant by means of feedback on the bias voltage and is independent of the incoming signal power. By combining a large negative electrothermal feedback with a load independent resistance, this approach can significantly linearise the response of the detector in the large signal limit. The electrothermal feedback is enhanced in comparison with the commonly applied voltage biasing, which further increases the speed of the detector. Furthermore, in frequency domain multiplexed readout, the sinusoidal bias voltages for each TES can be generated cryogenically with the readout SQUIDs.
Red-green-blue light sensitivity of oxide nanowire transistors for transparent display applications
Authors: Lee Sumi , Kim Seongmin , Janes David B. , Meyyappan M. , Ju Sanghyun
Published: January 2013

In this study, the sensitivity of oxide nanowire transistors under red (R, 470 nm), green (G, 530 nm), and blue (B, 625 nm) light illumination was investigated. As the wavelength of light illuminating the nanowire channel region became shorter, a negative shift of threshold voltage, degradation of subthreshold slope, and increase of on-current were observed. This phenomenon can be explained in terms of photo-induced holes, creating interfacial traps between the gate dielectric and nanowire channel or reacting with oxygen ions on the surface of the nanowires. Thus, the attempt to minimize characteristic changes due to all RGB light sources was performed by employing ultraviolet–ozone treatment and passivation process. As a result, we could successfully fabricate oxide nanowire transistors providing high optical reliability which has broadened the possibilities for applying it to transparent and/or flexible pixel operation circuitry for displays with high optical reliability.
An immunoreceptor tyrosine-based inhibition motif in varicella-zoster virus glycoprotein B regulates cell fusion and skin pathogenesis
Authors: Oliver Stefan L. , Brady Jennifer J. , Sommer Marvin H. , Reichelt Mike , Sung Phillip , Blau Helen M. , Arvin Ann M.
Published: January 2013

Herpesvirus entry functions of the conserved glycoproteins gB and gH–gL have been delineated, but their role in regulating cell–cell fusion is poorly understood. Varicella-zoster virus (VZV) infection provides a valuable model for investigating cell–cell fusion because of the importance of this process for pathogenesis in human skin and sensory ganglia. The present study identifies a canonical immunoreceptor tyrosine-based inhibition motif (ITIM) in the gB cytoplasmic domain (gB
cyt
) and demonstrates that the gB
cyt
is a tyrosine kinase substrate. Orbitrap mass spectrometry confirmed that Y881, central to the ITIM, is phosphorylated. To determine whether the gB
cyt
ITIM regulates gB/gH–gL–induced cell–cell fusion in vitro, tyrosine residues Y881 and Y920 in the gB
cyt
were substituted with phenylalanine separately or together. Recombinant viruses with these substitutions were generated to establish their effects on syncytia formation in replication in vitro and in the human skin xenograft model of VZV pathogenesis. The Y881F substitution caused significantly increased cell–cell fusion despite reduced cell-surface gB. Importantly, the Y881F or Y881/920F substitutions in VZV caused aggressive syncytia formation, reducing cell–cell spread. These in vitro effects of aggressive syncytia formation translated to severely impaired skin infection in vivo. In contrast, the Y920F substitution did not affect virus replication in vitro or in vivo. These observations suggest that gB modulates cell–cell fusion via an ITIM-mediated Y881 phosphorylation-dependent mechanism, supporting a unique concept that intracellular signaling through this gB
cyt
motif regulates VZV syncytia formation and is essential for skin pathogenesis.
Firm religiosity, bounded stakeholder salience, and stakeholder relationships in family firms
Authors: Fang Hanqinq , Randolph Robert Van de Graaff , Chrisman James J. , Barnett Tim
Published: January 2013

Utilizing a combination of stakeholder theory and social identity theory, we explore religiosity in family firms. The concept of bounded stakeholder salience is developed to describe situations where legitimacy is attached to stakeholders based on their possession of characteristics valued by the coalition of family decision-makers rather than their rightful claims to firm resources. We discuss how bounded stakeholder salience creates non-economic co-dependencies between family firms and their stakeholders that are likely to endure over time. Finally, we show that the satisfaction of non-economic goals through relationships with stakeholders with compatible religiosities may have residual effects on firm performance.
Serial and parallel processes in eye movement control: Current controversies and future directions
Authors: Murray Wayne S. , Fischer Martin H. , Tatler Benjamin W.
Published: January 2013

In this editorial for the Special Issue on Serial and Parallel Processing in Reading we explore the background to the current debate concerning whether the word recognition processes in reading are strictly serial–sequential or take place in an overlapping parallel fashion. We consider the history of the controversy and some of the underlying assumptions, together with an analysis of the types of evidence and arguments that have been adduced to both sides of the debate, concluding that both accounts necessarily presuppose some weakening of, or elasticity in, the eye–mind assumption. We then consider future directions, both for reading research and for scene viewing, and wrap up the editorial with a brief overview of the following articles and their conclusions.
Articulation Effects in Melody Recognition Memory
Authors: Wee Hun Lim Stephen , Goh Winston D.
Published: January 2013

Various surface features—timbre, tempo, and pitch—influence melody recognition memory, but articulation format effects, if any, remain unknown. For the first time, these effects were examined. In Experiment 1, melodies that remained in the same, or appeared in a different but similar, articulation format from study to test were recognized better than were melodies that were presented in a distinct format at test. A similar articulation format adequately induced matching processes to enhance recognition. Experiment 2 revealed that melodies rated as perceptually dissimilar on the basis of the location of the articulation mismatch did not impair recognition performance, suggesting an important boundary condition for articulation format effects on memory recognition—the matching of the memory trace and recognition probe may depend more on the overall proportion, rather than the temporal location, of the mismatch. The present findings are discussed in terms of a global matching advantage hypothesis.
Examining the Effects of Variation in Emotional Tone of Voice on Spoken Word Recognition
Authors: Krestar Maura L. , McLennan Conor T.
Published: January 2013

Emotional tone of voice (ETV) is essential for optimal verbal communication. Research has found that the impact of variation in nonlinguistic features of speech on spoken word recognition differs according to a time course. In the current study, we investigated whether intratalker variation in ETV follows the same time course in two long-term repetition priming experiments. We found that intratalker variability in ETVs affected reaction times to spoken words only when processing was relatively slow and difficult, not when processing was relatively fast and easy. These results provide evidence for the use of both abstract and episodic lexical representations for processing within-talker variability in ETV, depending on the time course of spoken word recognition.
Emergence of clones in sexual populations
Authors: Neher Richard A , Vucelja Marija , Mezard Mark , Shraiman Boris I
Published: January 2013

In sexual population, recombination reshuffles genetic variation and produces novel combinations of existing alleles, while selection amplifies the fittest genotypes in the population. If recombination is more rapid than selection, populations consist of a diverse mixture of many genotypes, as is observed in many populations. In the opposite regime, which is realized for example in the facultatively sexual populations that outcross in only a fraction of reproductive cycles, selection can amplify individual genotypes into large clones. Such clones emerge when the fitness advantage of some of the genotypes is large enough that they grow to a significant fraction of the population despite being broken down by recombination. The occurrence of this ‘clonal condensation’ depends, in addition to the outcrossing rate, on the heritability of fitness. Clonal condensation leads to a strong genetic heterogeneity of the population which is not adequately described by traditional population genetics measures, such as linkage disequilibrium. Here we point out the similarity between clonal condensation and the freezing transition in the random energy model of spin glasses. Guided by this analogy we explicitly calculate the probability, Y, that two individuals are genetically identical as a function of the key parameters of the model. While Y is the analog of the spin-glass order parameter, it is also closely related to rate of coalescence in population genetics: two individuals that are part of the same clone have a recent common ancestor.
Regulatory mode shift of Tbc1d1 is required for acquisition of insulin-responsive GLUT4-trafficking activity
Authors: Hatakeyama Hiroyasu , Kanzaki Makoto
Published: January 2013

Tbc1d1 is key to skeletal muscle GLUT4 regulation. By using GLUT4 nanometry combined with a cell-based reconstitution model, we uncover a shift in the regulatory mode of Tbc1d1 by showing that Tbc1d1 temporally acquires insulin responsiveness, which triggers GLUT4 trafficking only after an exercise-mimetic stimulus such as aminoimidazole carboxamide ribonucleotide (AICAR) pretreatment. The functional acquisition of insulin responsiveness requires Ser-237 phosphorylation and an intact phosphotyrosine-binding (PTB) 1 domain. Mutations in PTB1, including R125W (a natural mutant), thus result in complete loss of insulin-responsiveness acquisition, whereas AICAR-responsive GLUT4-liberation activity remains intact. Thus our data provide novel insights into temporal acquisition/memorization of Tbc1d1 insulin responsiveness, relying on the PTB1 domain, possibly a key factor in the beneficial effects of exercise on muscle insulin potency.
Total Phenolic Content and Antioxidant Capacity of Germinated, Popped, and Cooked Huauzontle (Chenopodium berlandieri spp. nuttalliae) Seeds
Authors: Martinez L. Chaires , Vargas M. A. Perez , del Angel A. I. Cantor , Bermudez F. Cruz , Avalos H. A. Jimenez
Published: January 2013

Raw, germinated, popped, and cooked huauzontle (Chenopodium berlandieri spp. nuttalliae) seeds were analyzed for the contents of phenolics extracted with water (WE), methanol, 1:1 (v/v) methanol/water (MWE), and 1.2M HCl in 1:1 (v/v) methanol/water (HMWE); radical scavenging capacity measured by the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) methods was studied. The effect of the system solvents used for the accurate quantification of antioxidant content and capacity showed that for raw, germinated, and cooked extracts, water gave the highest yield of total phenolic content, and MWE could recover the highest yield in popped extracts. Thermal treatments increased the flavonoid content more in all extracts than did the germinating process, with values ranging from 10 to 620 μg/g db of quercetin equivalents. However, all treatments significantly decreased (P < 0.05) the total phenolics (from 3,010 μg of gallic acid equivalents/g db in raw seeds WE to 710 μg/g db in germinated seeds MWE). HMWE in all treatments showed the highest values (up to 95.41%) by the DPPH method. With the ABTS method, germinated and popped MWE showed the highest values (up to 2,740mM Trolox/kg db). Based on these results, huauzontle seeds represent a useful potential ingredient for consumer health, because it has been shown to be a good source of total phenolic content having high antioxidant activity; moreover, for further studies, water appears to be effective as an extraction solvent of phenolic compounds.
Effects of Preharvest Nighttime Air Temperatures on Whiteness of Head Rice
Authors: Lanning Sarah , Siebenmorgen Terry
Published: January 2013

The effects of nighttime air temperature (NTAT) on the color of milled rice were investigated. Elevated NTATs occurring during the critical grain‐filling stages of kernel development impacted the color of head rice. Six cultivars, grown at multiple field locations from northern to southern Arkansas during 2007–2010, were evaluated for head rice color, using whiteness (L*) and yellowness (b*) indices, and for chalk. Nighttime temperatures were recorded throughout production at each of the selected locations, and the 95th percentiles of NTAT frequencies (NT95) were calculated for each cultivar's reproductive (R) stages. Head rice color values were analyzed in relation to NT95 occurring during the grain‐filling (R6–R8) stages and in relation to percent chalkiness. Whiteness generally increased with increasing NTAT and with increasing chalkiness. Yellowness decreased as chalkiness increased. Moreover, kernel whiteness increased even when measured in the absence of chalky kernels, suggesting that starch granule organization throughout the kernel, even in nonchalky portions, was altered, which could result in compromised physical integrity and processing functionality. Cultivars varied in their susceptibility to the effect of NTAT on color, as has been previously demonstrated with milling quality and functional properties.