bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of peripheral charge induced low frequency capacitance-voltage behaviour in metal-oxide-semiconductor capacitors on Si and GaAs substrates
Authors: O’Connor É. , Cherkaoui K. , Monaghan S. , O’Connell D. , Povey I. , Casey P. , Newcomb S. B. , Gomeniuk Y. Y. , Provenzano G. , Crupi F. , Hughes G. , Hurley P. K.
Published: June 2012

We report on experimental observations of room temperature low frequency capacitance-voltage (CV) behaviour in metal oxide semiconductor (MOS) capacitors incorporating high dielectric constant (high-k) gate oxides, measured at ac signal frequencies (2 kHz to 1 MHz), where a low frequency response is not typically expected for Si or GaAs MOS devices. An analysis of the inversion regions of the CV characteristics as a function of area and ac signal frequency for both n and p doped Si and GaAs substrates indicates that the source of the low frequency CV response is an inversion of the semiconductor/high-k interface in the peripheral regions outside the area defined by the metal gate electrode, which is caused by charge in the high-k oxide and/or residual charge on the high-k oxide surface. This effect is reported for MOS capacitors incorporating either MgO or GdSiOx as the high-k layers on Si and also for Al2O3 layers on GaAs(111B). In the case of NiSi/MgO/Si structures, a low frequency CV response is observed on the p-type devices, but is absent in the n-type devices, consistent with positive charge (>8 × 1010 cm−2) on the MgO oxide surface. In the case of the TiN/GdSiOx/Si structures, the peripheral inversion effect is observed for n-type devices, in this case confirmed by the absence of such effects on the p-type devices. Finally, for the case of Au/Ni/Al2O3/GaAs(111B) structures, a low-frequency CV response is observed for n-type devices only, indicating that negative charge (>3 × 1012 cm−2) on the surface or in the bulk of the oxide is responsible for the peripheral inversion effect.
Vacancy mediated room temperature ferromagnetism in Co-doped Dy2O3
Authors: Bandyopadhyay A. , Sutradhar S. , Sarkar B. J. , Deb A. K. , Chakrabarti P. K.
Published: June 2012

Nanoparticles of Co doped dysprosium oxide [Dy1.90Co0.10O3] were prepared by co-precipitating the precursor salts in presence of air and argon gas. Crystallographic phase and substitution of Co-ion in Dy2O3 were confirmed by Rietveld analysis of the x-ray diffraction patterns. Magnetic susceptibility and magnetization as a function of temperature and magnetic field were measured by Faraday and Superconducting quantum inteference device (SQUID) magnetometers, which showed that the sample synthesized in the inert atmosphere is ferromagnetic at room temperature. But no such effect has been observed in the other sample. This observation confirmed that vacancy mediated ferromagnetism can be introduced in the Co-doped dysprosium oxide.
Pre-combustion CO2 capture by transition metal ions embedded in phthalocyanine sheets
Authors: Lü Kun , Zhou Jian , Zhou Le , Chen X. S. , Chan Siew Hwa , Sun Qiang
Published: June 2012

Transition metal (TM) embedded two-dimensional phthalocyanine (Pc) sheets have been recently synthesized in experiments [M. Abel, S. Clair, O. Ourdjini, M. Mossoyan, and L. Porte, J. Am. Chem. Soc. 133, 1203 (2010)]10.1021/ja108628r, where the transition metal ions are uniformly distributed in porous structures, providing the possibility of capturing gas molecules. Using first principles and grand canonical Monte Carlo simulations, TMPc sheets (TM = Sc, Ti, and Fe) are studied for pre-combustion CO2 capture by considering the adsorptions of H2/CO2 gas mixtures. It is found that ScPc sheet shows a good selectivity for CO2, and the excess uptake capacity of single-component CO2 on ScPc sheet at 298 K and 50 bar is found to be 2949 mg/g, larger than that of any other reported porous materials. Furthermore, electrostatic potential and natural bond orbital analyses are performed to reveal the underlying interaction mechanisms, showing that electrostatic interactions as well as the donation and back donation of electrons between the transition metal ions and the CO2 molecules play a key role in the capture.
Precipitation of Pt nanocrystallites from BaO-TiO2-GeO2 remelted glass
Authors: Masai Hirokazu , Hamaguchi Katsumi , Suzuki Yoshiyuki , Iwasaki Kenichiro , Ihara Rie , Takahashi Yoshihiro , Fujiwara Takumi
Published: June 2012

We have examined the correlation between the thermal and optical properties of 30BaO-15TiO2-55GeO2 glass and its mode of preparation, i.e., the different temperatures at which the glass melts were held in a molten state (melt temperature). The changes in the absorption coefficients and the refractive indices, which increased with the increasing melt temperature, were reversible, and temperature-dependent structures were formed in the glass. In the remelted glass with short remelting duration, a black coloration and the precipitation of Pt nanocrystallites were observed. The precipitated Pt nanocrystallites acted as nucleation sites to induce crystallization by heat treatment at 10 °C below the glass transition temperature.
Electron correlation effects on the electric properties of fluorinated polyacetylene
Authors: Abreu L. M. , Fonseca T. L. , Castro M. A.
Published: June 2012

Using the Hartree-Fock (HF) and second-order Møller-Plesset perturbation theory (MP2) methods with the 6-31G(d) basis set, we have investigated the chain length dependence of the longitudinal dipole moment and longitudinal components of the static linear polarizability, first and second hyperpolarizabilities of fluorinated polyacetylene chains. It is found that geometry changes caused by the electron correlation (EC) effects imply in marked increases of the electric properties but to obtain a reliable description it is necessary to properly account for both geometric and electronic changes. Based on the fast convergence pattern presented by the MP2/HF ratios and from the converged HF oligomeric results, we have estimated the MP2 electric properties of long chains. The asymptotic value for the MP2 second hyperpolarizability per unit cell is estimated in 1.9 × 108 a.u. This result is one order of magnitude larger than the corresponding result reported for the unsubstituted polyacetylene chains.
Structures of small mixed krypton-xenon clusters
Authors: Nagasaka Masanari , Kosugi Nobuhiro , Rühl Eckart
Published: June 2012

Structures of small mixed krypton-xenon clusters of different compositions with an average size of 30–37 atoms are investigated. The Kr 3d5/2 and Xe 4d5/2 surface core level shifts and photoelectron intensities originating from corner, edge, and face/bulk sites are analyzed by using soft x-ray photoelectron spectroscopy. Structural models are derived from these experiments, which are confirmed by theoretical simulation taking induced dipole interactions into account. It is found that one or two small Xe cores are partly embedded in the surface of the Kr clusters. These may grow and merge leading to a phase separation between the two rare gas moieties in mixed clusters with increasing the Xe content.
Zener tunneling: Congruence between semi-classical and quantum ballistic formalisms
Authors: Ganapathi Kartik , Salahuddin Sayeef
Published: June 2012

We compare the results of self-consistent ballistic quantum transport simulation of Zener tunneling in InAs, a direct bandgap semiconductor, with corresponding semi-classical solutions using the well-known Kane’s model and the Wentzel-Kramers-Brillouin (WKB) approximation. We find a qualitative difference between solutions obtained from Kane’s formulation and rigorous quantum-mechanical formalism. However, the WKB solution, with evaluation of action integral along the tunneling paths determined from the nearest neighbor sp3s* Hamiltonian, is shown to provide qualitative agreement. We discuss the issues involved in fitting semi-classical solutions with their quantum counterpart and also present a brief comparison of our results with experimental data.
Simultaneous magneto-optical Kerr effect and Sixtus-Tonks method for analyzing the shape of propagating domain walls in ultrathin magnetic wires
Authors: Ţibu M. , Lostun M. , Óvári T.-A. , Chiriac H.
Published: June 2012

The controlled nucleation and propagation of magnetic domain walls in ultrathin ferromagnetic wires, such as nanowires and submicrometer wires, is extremely important for the development of new high performance magnetic domain wall logic devices. Therefore, it is equally essential to possess adequate advanced experimental investigation techniques in order to be able to achieve a comprehensive in situ analysis of as many as possible parameters related to the domain wall propagation, e.g., wall shape besides wall velocity and position. In this paper, we report on a method developed specifically for the investigation of the shape of propagating magnetic domain walls in ultrathin magnetic wires, i.e., with the diameter of the magnetic wire in the range 100–950 nm. The newly developed experimental method is based on the simultaneous use of two full-fledged experimental techniques: the magneto-optical Kerr effect for analyzing the surface effects of the passing domain wall and the Sixtus-Tonks method for the investigation of the entire moving wall. The results obtained offer essential information about the shape of the propagating magnetic domain walls, being unique to this new method.
The various manifestations of collisionless dissipation in wave propagation
Authors: Bénisti Didier , Morice Olivier , Gremillet Laurent
Published: June 2012

The propagation of an electrostatic wave packet inside a collisionless and initially Maxwellian plasma is always dissipative because of the irreversible acceleration of the electrons by the wave. Then, in the linear regime, the wave packet is Landau damped, so that in the reference frame moving at the group velocity, the wave amplitude decays exponentially with time. In the nonlinear regime, once phase mixing has occurred and when the electron motion is nearly adiabatic, the damping rate is strongly reduced compared to the Landau one, so that the wave amplitude remains nearly constant along the characteristics. Yet, we show here that the electrons are still globally accelerated by the wave packet, and in one dimension, this leads to a non local amplitude dependence of the group velocity. As a result, a freely propagating wave packet would shrink, and therefore, so would its total energy. In more than one dimension, not only does the magnitude of the group velocity nonlinearly vary, but also its direction. In the weakly nonlinear regime, when the collisionless damping rate is still significant compared to its linear value, the group velocity is directed towards the outside of the wave packet and tends to increase its transverse extent, while the opposite is true once the wave is essentially undamped. The impact of the nonlinear variation of the group velocity on the transverse size of the wave packet is quantified, and compared to that induced by the self-focussing due to wave front bowing.
Tomographic imaging system for measuring impurity line emission in a field-reversed configuration
Authors: Roche T. , Bolte N. , Garate E. , Heidbrink W. W. , McWilliams R. , Wessel F.
Published: June 2012

A 16 chord optical tomography system has been developed and implemented in the flux coil generated-field reversed configuration (FRC). The chords are arranged in two fans of eight, which cover ∼35% of the vessel area at the midplane. Each illuminate separate photomultiplier tubes (PMTs) which are fitted with narrow band-pass filters. In this case, filters are centered at 434.8 nm to measure emission from singly ionized argon. PMT crosstalk is negligible. Background noise due to electron radiation and Hγ line radiation is <10% of argon emission. The spatial resolution of the reconstruction is 1.5 cm. Argon is introduced using a puff valve and tube designed to impart the gas into the system as the FRC is forming. Reconstruction of experimental data results in time-dependent, 2D emissivity profiles of the impurity ions. Analysis of these data show radial, cross-field diffusion to be in the range of 10–103 m2/s during FRC equilibrium.
Axisymmetric nonlinear waves and structures in Hall plasmas
Authors: Islam Tanim
Published: June 2012

In this paper, a general equation for the evolution of an axisymmetric magnetic field in a Hall plasma is derived, with an integral similar to the Grad-Shafranov equation. Special solutions arising from curvature—whistler drift modes that propagate along the electron drift as a Burger’s shock and nonlinear periodic and soliton-like solutions to the generalized Grad-Shafranov integral—are analyzed. We derive analytical and numerical solutions in a classical electron-ion Hall plasma, in which electrons and ions are the only species in the plasmas. Results may then be applied to the following low-ionized astrophysical plasmas: in protostellar disks, in which the ions may be coupled to the motion of gases; and in molecular clouds and protostellar jets, in which the much heavier charged dust in a dusty Hall plasma may be collisionally coupled to the gas.
Molecular dynamics simulations of a hard sphere crystal and reaction-like mechanism for homogeneous melting
Authors: Lemarchand C. A.
Published: June 2012

Molecular dynamics simulations of a hard sphere crystal are performed for volume fractions ranging from solidification point to melting point. A local bond order parameter is chosen to assign a nature, liquid or solid, to a particle. The probability for a liquid or solid particle to change state presents a typical sigmoid shape as the nature of its neighbors changes. Using this property, I propose a reaction-like mechanism and introduce a small number of rate constants. A mean-field approach to melting and a kinetic Monte Carlo algorithm on a lattice are derived from these chemical processes. The results of these models successfully compare with molecular dynamics simulations, proving that the main properties of melting can be captured by a small number of dynamical parameters.
Thermoelectric properties of FeGa3-type narrow-bandgap intermetallic compounds Ru(Ga,In)3: Experimental and calculational studies
Authors: Takagiwa Y. , Kitahara K. , Matsubayashi Y. , Kimura K.
Published: June 2012

The thermoelectric properties of polycrystalline binary narrow-bandgap intermetallic RuGa3 and RuIn3 compounds have been investigated in the temperature range from 373 K to 973 K. These compounds exhibit semiconductor-like transport properties with large Seebeck coefficients of −560 μV/K and 280 μV/K at 373 K for RuGa3 and RuIn3, respectively. The Seebeck coefficient of RuGa3 changed rapidly from large negative to large positive values around 500 K, which is consistent with our calculation based on the full-potential-linearized-augmented-plane-wave method. In contrast, RuIn3 is a p-type material at its operating temperature. The dimensionless figures of merit ZT of pure compounds reached maximum values of 0.13 and 0.17 at about 973 K and 773 K, respectively. The potential maximum ZT value was evaluated using the Boltzmann transport equation and can exceed unity by electron- or hole-doping for both compounds. By substituting Co for Ru in RuIn3, n-type thermoelectric materials (ZTmax = 0.10 at 473 K) were obtained. We suggest that ZT will be enhanced by further effective electron-doping.
Low energy electron stimulated desorption from DNA films dosed with oxygen
Authors: Mirsaleh-Kohan Nasrin , Bass Andrew D. , Cloutier Pierre , Massey Sylvain , Sanche Léon
Published: June 2012

Desorption of anions stimulated by 1–18 eV electron impact on self-assembled monolayer (SAM) films of single DNA strands is measured as a function of film temperature (50–250 K). The SAMs, composed of 10 nucleotides, are dosed with O2. The OH− desorption yields increase markedly with exposure to O2 at 50 K and are further enhanced upon heating. In contrast, the desorption yields of O−, attributable to dissociative electron attachment to trapped O2 molecules decrease with heating. Irradiation of the DNA films prior to the deposition of O2 shows that this surprising increase in OH− desorption, at elevated temperatures, arises from the reaction of O2 with damaged DNA sites. These results thus appear to be a manifestation of the so-called “oxygen fixation” effect, well known in radiobiology.
Plasma-assisted growth and nitrogen doping of graphene films
Authors: Wang C. D. , Yuen M. F. , Ng T. W. , Jha S. K. , Lu Z. Z. , Kwok S. Y. , Wong T. L. , Yang X. , Lee C. S. , Lee S. T. , Zhang W. J.
Published: June 2012

Microwave plasmas were employed to synthesize single- or double-layer graphene sheets on copper foils using a solid carbon source, polymethylmetacrylate. The utilization of reactive plasmas enables the graphene growth at reduced temperatures as compared to conventional thermal chemical vapor deposition processes. The effects of substrate temperature on graphene quality were studied based on Raman analysis, and a reduction of defects at elevated temperature was observed. Moreover, a facile approach to incorporate nitrogen into graphene by plasma treatment in a nitrogen/hydrogen gas mixture was demonstrated, and most of the nitrogen atoms were verified to be pyridinelike in carbon network.
The importance of strain on spin-spin coupling in Pr5/8Ca3/8MnO3 single crystal film
Authors: Fu Xinwen , Gao Yuze , Wu Zhiwei , Zhang Jincang , Li Qing , Cao Guixin
Published: June 2012

The influence of anisotropic strains on coupling spins is systematically investigated in pulsed laser deposited single crystal Pr5/8Ca3/8MnO3 film. The substrate was chosen to introduce tensile and compressive strain onto the film. Various experiments, i.e., zero field cooled/field cooled (ZFC/FC) magnetization measurement, hysteresis loops, and exchange bias field detection, have revealed distinct difference along two perpendicular in-plane axes which represent tensile and compressive strain orientation, respectively. We found that the observed phenomenon can be explained by the external strain effect.
Direct observation and mechanism of increased emission sites in Fe-coated microcrystalline diamond films
Authors: Panda Kalpataru , Sundaravel B. , Panigrahi B. K. , Huang Pin-Chang , Shih Wen-Ching , Chen Huang-Chin , Lin I-Nan
Published: June 2012

The electron field emission (EFE) properties of microcrystalline diamond (MCD) films are significantly enhanced due to the Fe coating and post-annealing processes. The 900 °C post-annealed Fe coated diamond films exhibit the best EFE properties, with a turn on field (E0) of 3.42 V/μm and attain EFE current density (Je) of 170 μA/cm2 at 7.5 V/μm. Scanning tunnelling spectroscopy (STS) in current imaging tunnelling spectroscopy mode clearly shows the increased number density of emission sites in Fe-coated and post-annealed MCD films than the as-prepared ones. Emission is seen from the boundaries of the Fe (or Fe3C) nanoparticles formed during the annealing process. In STS measurement, the normalized conductance dI/dVI/V versus V curves indicate nearly metallic band gap, at the boundaries of Fe (or Fe3C) nanoparticles. Microstructural analysis indicates that the mechanism for improved EFE properties is due to the formation of nanographite that surrounds the Fe (or Fe3C) nanoparticles.
Arc-based smoothing of ion beam intensity on targets
Authors: Friedman Alex
Published: June 2012

By manipulating a set of ion beams upstream of a target, it is possible to arrange for a smoother deposition pattern, so as to achieve more uniform illumination of the target. A uniform energy deposition pattern is important for applications including ion-beam-driven high energy density physics and heavy-ion beam-driven inertial fusion energy (“heavy-ion fusion”). Here, we consider an approach to such smoothing that is based on rapidly “wobbling” each of the beams back and forth along a short arc-shaped path, via oscillating fields applied upstream of the final pulse compression. In this technique, uniformity is achieved in the time-averaged sense; this is sufficient provided the beam oscillation timescale is short relative to the hydrodynamic timescale of the target implosion. This work builds on two earlier concepts: elliptical beams applied to a distributed-radiator target [D. A. Callahan and M. Tabak, Phys. Plasmas 7, 2083 (2000)] and beams that are wobbled so as to trace a number of full rotations around a circular or elliptical path [R. C. Arnold et al., Nucl. Instrum. Methods 199, 557 (1982)]. Here, we describe the arc-based smoothing approach and compare it to results obtainable using an elliptical-beam prescription. In particular, we assess the potential of these approaches for minimization of azimuthal asymmetry, for the case of a ring of beams arranged on a cone. It is found that, for small numbers of beams on the ring, the arc-based smoothing approach offers superior uniformity. In contrast with the full-rotation approach, arc-based smoothing remains usable when the geometry precludes wobbling the beams around a full circle, e.g., for the X-target [E. Henestroza, B. G. Logan, and L. J. Perkins, Phys. Plasmas 18, 032702 (2011)] and some classes of distributed-radiator targets.
Stability and migration of large oxygen clusters in UO2+x: Density functional theory calculations
Authors: Andersson D. A. , Espinosa-Faller F. J. , Uberuaga B. P. , Conradson S. D.
Published: June 2012

Using ab initio molecular dynamics simulations and nudged elastic band calculations we examine the finite temperature stability, transition pathways, and migration mechanisms of large oxygen clusters in UO2+x. Here we specifically consider the recently proposed split quad-interstitial and cuboctahedral oxygen clusters. It is shown that isolated cuboctahedral clusters may transform into more stable configurations that are closely linked to the split quad-interstitial. The split quad-interstitial is stable with respect to single interstitials occupying the empty octahedral holes of the UO2 lattice. In order to better understand discrepancies between theory and experiments, the simulated atomic pair distribution functions for the split quad-interstitial structures are analyzed with respect to the distribution function for U4O9 previously obtained from neutron diffraction data. Our nudged elastic band calculations suggest that the split quad-interstitial may migrate by translating one of its constituent di-interstitial clusters via a barrier that is lower than the corresponding barrier for individual interstitials, but higher than the barrier for the most stable di-interstitial cluster.
Switching time of a single spin in linearly varying field
Authors: Uesaka Yasutaro , Suzuki Yoshio , Kitakami Osamu , Nakatani Yoshinobu , Hayashi Nobuo , Fukushima Hiroshi
Published: June 2012

We studied the switching time of a single spin in a field varying linearly in time using a micromagnetics simulation based on the Landau-Lifshitz-Gilbert equation. The applied field larger than the switching field or coercivity is not enough for a spin to switch but some duration of time is also necessary. We found that the value of C1 defined by C1=∫(H−H1)dt was constant when the rate of change in the field was larger than 10 × γHk2, where γ is the gyromagnetic ratio with g value = 2, H is the applied field, H1 is a constant, and Hk is the anisotropy field of the spin. The integration is taken from the time the spin begins switching to the switching time. The equation is a generalized form of the equation, C0=(H−H0)τsw, in a constant field H. Here, C0 and H0 are constants, and τsw is the switching time. We found that C1 in the region dH/dt>10×γHK2 and C0 in the region H≫HK are the same, but that H1 does not coincide with H0. We found that the head field rise time has a very small effect on the switching field and time of recording media.
The pyroelectric behavior of lead free ferroelectric ceramics in thermally stimulated depolarization current measurements
Authors: González-Abreu Y. , Peláiz-Barranco A. , Garcia-Wong A. C. , Guerra J. D. S.
Published: June 2012

The present paper shows a detailed analysis on the thermally stimulated processes in barium modified SrBi2Nb2O9 ferroelectric bi-layered perovskite, which is one of the most promising candidates for non-volatile random access memory applications because of its excellent fatigue-resistant properties. A numerical method is used to separate the real pyroelectric current from the other thermally stimulated processes. A discharge due to the space-charge injected during the poling process, the pyroelectric response, and a conductive process are discussed in a wide temperature range from ferroelectric to paraelectric phase. The pyroelectric response is separated from the other components to evaluate the polarization behavior and some pyroelectric parameters. The remanent polarization, the pyroelectric coefficient, and the merit figure are evaluated, which show good results.
Ferromagnetism and manipulation of topological surface states in Bi2Se3 family by 2p light elements
Authors: Niu Chengwang , Dai Ying , Zhang Zhenkui , Ma Yandong , Huang Baibiao
Published: June 2012

The manipulation effects by doping of 2p light elements X (X = B, C, and N) on topological surface states in V2VI3 (V = Bi and Sb, VI = Se and Te) are systemically explored. Our results unveil that X doping at anion sites can induce magnetic moments and gap opening at the Dirac point. To have a stable magnetic ground state, the dopant 2p states must be sufficiently localized, which closely depends on the X-V bond lengths. The incorporation of 2p dopants paves a promising way of tuning the properties of topological insulators and may find applications in spintronics.
Edge stresses of non-stoichiometric edges in two-dimensional crystals
Authors: Deng Junkai , Fampiou Ioanna , Liu J. Z. , Ramasubramaniam Ashwin , Medhekar N. V.
Published: June 2012

The elastic properties of edges are among the most fundamental properties of finite two-dimensional (2D) crystals. Using a combination of the first-principles density functional theory calculations and a continuum elasticity model, we present an efficient technique to determine the edge stresses of non-stoichiometric orientations in multicomponent 2D crystals. Using BN and MoS2 as prototypical examples of 2D binary monolayers with threefold in-plane symmetry, we unambiguously compute unique edge stresses of commonly observed non-stoichiometric edges. Our results show that the edge stresses for these structurally distinct orientations can differ significantly from the average values that have been typically reported to date.
Technology diffusion and carbon intensity of electric power in China
Authors: Yu Bo , Yao Xilong
Published: June 2012

The relationship between technology and carbon intensity has received a lot of attention in recent years. This paper focuses on the impacts of diffusion of new energy technologies and thermal power technology on carbon intensity of electricity production during 1996–2009. The results show that new energy maintained less than 20% over the period 1996–2009, and it can also decrease the carbon intensity of electricity power. However, the decline of thermal power carbon intensity driven by its technology diffusion was the main driver force of electricity power carbon intensity. However, the effect of thermal power technology diffusion was also different in different years as the speed of thermal power technology diffusion and technological learning ability was different.
Microfluidic three-dimensional hydrodynamic flow focusing for the rapid protein concentration analysis
Authors: Hong Sungmin , Tsou Pei-Hsiang , Chou Chao-Kai , Yamaguchi Hirohito , Su Chin B. , Hung Mien-Chie , Kameoka Jun
Published: June 2012

A simple microfluidic 3D hydrodynamic flow focusing device has been developed and demonstrated quantitative determinations of quantum dot 525 with antibody (QD525-antibody) and hemagglutinin epitope tagged MAX (HA-MAX) protein concentrations. This device had a step depth cross junction structure at a hydrodynamic flow focusing point at which the analyte stream was flowed into a main detection channel and pinched not only horizontally but also vertically by two sheath streams. As a result, a triangular cross-sectional flow profile of the analyte stream was formed and the laser was focused on the top of the triangular shaped analyte stream. Since the detection volume was smaller than the radius of laser spot, a photon burst histogram showed Gaussian distribution, which was necessary for the quantitative analysis of protein concentration. By using this approach, a linear concentration curve of QD525-antibody down to 10 pM was demonstrated. In addition, the concentration of HA-MAX protein in HEK293 cell lysate was determined as 0.283 ± 0.015 nM. This approach requires for only 1 min determining protein concentration. As the best of our knowledge, this is the first time to determinate protein concentration by using single molecule detection techniques.
Computational measurement of void percolation thresholds of oblate particles and thin plate composites
Authors: Yi Y. B. , Esmail K.
Published: June 2012

The void percolation thresholds of random oblate particles and thin plate composites are measured computationally using the lattice mapping technique and the Monte Carlo simulation scheme. Two types of spatially uncorrelated inclusions have been investigated: oblate ellipsoids and elliptical thin plates, with which the site and bond percolation systems are developed separately. The results are obtained from the finite-size lattices followed by a mathematical extrapolation to the infinite domains. The computational results are validated by a comparison with the numerical solutions of the limiting cases found in the literature. It is concluded that the void percolation thresholds of oblate inclusions have a much stronger dependence on the geometric aspect ratio of the inclusions compared to those of the prolate counterparts. In the limit, the percolation threshold η is measured to be 22.86 for circular thin disks. Approximate solutions are presented in the form of polynomial functions and Pade approximants. The results have potential applications in composite material designs and molecular diffusion problems.
Variation of ferroelectric properties in (Bi,Pr)(Fe,Mn)O3/SrRuO3-Pt/CoFe2O4 layered film structure by applying direct current magnetic field
Authors: Liu Chen , Kawae Takeshi , Tsukada Yoshinori , Morimoto Akiharu , Naganuma Hiroshi , Nakajima Takashi , Okamura Soichiro
Published: June 2012

We report the preparation of (Bi,Pr)(Fe,Mn)O3(BPFM)/SrRuO3 (SRO)-Pt/CoFe2O4(CFO) layered film structure on (100) SrTiO3 substrate by pulsed laser deposition method and their structural and electrical properties. Favorable ferroelectric properties of BPFM were observed in the layered film structure with (100)-oriented growth of BPFM, SRO, and CFO. Variation of polarization vs electric field loops of BPFM by applying DC magnet field was observed, and the remnant polarization was found to increase by 3% with increasing the applied magnetic field from 0 to 10 kOe. The magnetoelectric coefficient in the present structure was estimated to be 1.5 V/(cmOe).
Electronic structure and linear magnetoresistance of the gapless topological insulator PtLuSb
Authors: Shekhar Chandra , Ouardi Siham , Fecher Gerhard H. , Kumar Nayak Ajaya , Felser Claudia , Ikenaga Eiji
Published: June 2012

The present work reports on the experimental investigation of electronic structure and transport properties of the proposed topological insulator PtLuSb. The electronic structure was investigated by means of polarization dependent hard x-ray photoelectron spectroscopy. The valence band spectra exhibit a linear behavior close to the Fermi energy, as is typical for massless electrons. The transport properties are similar to that of a gapless semiconductor with low carrier concentration. This compound also exhibits an exceptionally high Hall mobility. At low temperatures, the magnetoresistance changes linearly with the applied magnetic field, whereas it exhibits a quadratic nature at high temperatures. A tentative relation between linear magnetoresistance and high mobility is discussed.
Carrier transport mechanism of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) films by incorporating ZnO nanoparticles
Authors: Lin Yow-Jon , Tsai Cheng-Lung , Su Yu-Chao , Liu Day-Shan
Published: June 2012

The carrier transport mechanism of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) having ZnO nanoparticles, denoted ZnO-doped PEDOT:PSS, is investigated. Conductivity proportional to ZnO doping was observed at 300 K. The improved electrical conductivity is considered to mainly come from the mobility enhancement. The carrier mobility in ZnO-doped PEDOT:PSS samples exhibits unexpectedly strong temperature dependence, implying the domination of tunneling in the whole range of temperatures. An exhibition of high mobility of ZnO-doped PEDOT:PSS samples is attributed to a combined effect of the weak electron-phonon couplings and changes in the chemical structure of PEDOT:PSS.
The adoption behavior of new energy automotive technology in Chinese firms: A knowledge rigidity perspective
Authors: Zhou Zhong , Chen Zhigao , Li Ying
Published: June 2012

Taking related interactive factors into account, this paper develops a system dynamics model for describing the impact of knowledge rigidity on adoption of new energy automotive technology in Chinese firms. The simulation results indicate that knowledge rigidity, which derives from firm’s excessive dependence on traditional automotive technology, inhibits its adoption of new energy automotive technology. Further, legitimate policy on carbon emission restriction can weaken the knowledge rigidity and prompt firms to adopt new energy technology. Governmental subsidy encourages the firms to further develop the production capacity of new energy technology, though it only works after the mass production is initiated. In addition, decision making analysis is conducted, and suggestions for Chinese automotive firms and government are provided.
Catalytic behavior of metallic particles in anisotropic etching of Ge(100) surfaces in water mediated by dissolved oxygen
Authors: Kawase Tatsuya , Mura Atsushi , Nishitani Keisuke , Kawai Yoshie , Kawai Kentaro , Uchikoshi Junichi , Morita Mizuho , Arima Kenta
Published: June 2012

The authors demonstrate that Ge(100) surfaces containing metallic particles are etched anisotropically in water. This originates from the catalytic reduction of dissolved oxygen (O2) in water to water molecules (H2O) on the metallic particles, which is followed by the enhanced oxidation of Ge around the particles. The soluble nature of Ge oxide (GeO2) in water promotes the formation of inverted pyramidal etch pits composed of (111) microfacets. On the basis of the results, the authors propose strategies for avoiding unwanted surface roughening during the wet cleaning of Ge.
Patterns of Social Capital, Voluntary Activity, and Area Deprivation in England
Authors: McCulloch Andrew , Mohan John , Smith Peter
Published: June 2012

This study uses data from the 2005 and 2007 Citizenship Survey to map broad differences in levels of volunteering and social capital between ninety different types of place in England, characterised by their regional location and level of deprivation. A measure of social capital in each type of place is constructed using a multivariate multilevel statistical model and the association with rates of volunteering is then examined. The results show a positive association at the area level between the level of formal volunteering and informal volunteering and the level of social capital. The rate of both formal and informal volunteering was, however, unrelated to the level of social capital after controlling for area deprivation. These results raise concerns about the ability of volunteering to change the social characteristics of deprived areas independently of their material circumstances. Communities have strengths primarily in areas concerned with maintaining social order rather than creating economic growth. Policies to tackle area deprivation need to concentrate on linking deprived areas up to economic opportunities in more affluent surrounding areas rather than on local strategies based on self-help.
Peasants' Counterplots against the State Monopoly of the Rural Urbanization Process: Urban Villages and ‘Small Property Housing’ in Beijing, China
Authors: Liu Ran , Wong Tai-Chee , Liu Shenghe
Published: June 2012

Chinese economic reforms have moved Mao's antiurban paradigm to an urban-driven paradigm. Since the late 1980s, modernist reforms have led to large scales of urbanization, particularly in the suburban rural zones. Extensive amounts of farmland in Beijing have been expropriated for conversion to urban use to bolster economic growth. Whilst market reforms have resulted in a substantial rise in land values, as the state is effectively the sole landowner, little of the ‘surplus value’ thus created has gone to the peasants who merely have user rights. In response, peasants have created an informal sales and rental housing market to make up for their loss in livelihood, and to meet the demand of Beijing residents and low-income migrant workers. Supported by site surveys, this paper examines peasants' rights to the city, other property rights, and the ways in which they exercise their ‘illegal’ rights and the mechanism by which the ‘surplus value’ is shared between the state, the developers, and, albeit limited, the peasants in the urbanization process. More intricate policy measures have since been taken by the Chinese government in pacifying the social tension arising from inequitable housing distribution.
Modeling Social Networks in Geographic Space: Approach and Empirical Application
Authors: Arentze Theo , van den Berg Pauline , Timmermans Harry
Published: June 2012

Social activities are responsible for a large proportion of travel demands of individuals. Modeling of the social network of a studied population offers a basis to predict social travel in a more comprehensive way than currently is possible. In this paper we develop a method to generate a whole social network for a given population focusing on friendship relationships. The core of the method is a friendship-formation model that predicts for any two given persons from a population the probability that a friendship relationship exists between the persons. The model takes into account the degree of similarity in attributes, geographic distance between the persons as well as threshold values representing the persons' opportunities and base preferences for engagement in a friendship relationship. We show how the model can be estimated on the basis of observed personal social networks from a sample of individuals. We estimate and test the model using data collected in a recent survey in Eindhoven, The Netherlands. The results indicate that the model is able to generate networks that display the same structural properties as we find in the sample data. A synthetic network generated in this way can be used to microsimulate social interactions in a population in geographic space
Spending, Contacting, and Voting: The 2010 British General Election in the Constituencies
Authors: Johnston Ron , Pattie Charles , Cutts David , Fisher Justin
Published: June 2012

A substantial body of recent research has uncovered the impact of constituency campaigns on British general election outcomes, using the published returns of candidates' spending as a proxy measure for their campaigns' intensity—the more spent, the greater the intensity of the local campaign, and the greater the intensity of campaigning, the better their performance in the constituency, and the poorer their opponents' performance. These data refer only to the last few weeks before the election, however, and cannot identify how spending affects behaviour. For the latter, it is argued that spending is a proxy measure for the amount of contact between candidates and voters; the greater the amount spent the greater the probability that an elector contacted will vote for the relevant party. It has been difficult to evaluate this argument until the 2010 general election, however, for which the availability of a large panel survey that includes information on those contacts allows a full assessment of the hypothesis. The results show that the more spent in a constituency the greater the volume and range of contacts there, which in turn increases the probability of individuals voting for the party concerned.
Manipulating Material Hydro-Worlds: Rethinking Human and More-Than-Human Relationality through Offshore Radio Piracy
Authors: Peters Kimberley
Published: June 2012

Lambert et al state that emerging geographical studies of social and cultural worlds at sea should take into account the currents, textures, and more-than-human elements of the oceans. In spite of this call there has been little work which seriously considers the physical, more-than-human geography of the sea—its very materiality—and how it comes into play with social and cultural life. This paper draws on the watery excursions of Radio Caroline's pop-pirate broadcasting ships, examining the ways in which the materiality of the sea as a ‘hydro’ state (that is, motionful, deep, and dynamic), has agency; resulting in a variety of visceral affects for those at sea, and also for those listening to the station's transmissions back on dry land. The paper begins by examining the strategic locations of the pop-pirate vessels whilst at sea to manipulate the motionful impact of the ocean and how, in turn, the depth and dynamism of the sea were harnessed to create unique audio experiences for those listening. The paper then continues to explore the ways in which, even with such manipulations and harnessing, crew members sometimes had little control of their situation; resulting in disorientation and confusion as the power of the sea immersed them. Through these two sections it is contended that the specific quality of the sea opens up new relational understandings between the human and more-than-human worlds. Humans cannot assert influence back onto the materiality of the sea as they might the earth, and therefore must negotiate the force of the ocean through forms of strategy and management; manipulations of materiality and affect, forming new cocomposed relations. It is concluded that further studies, both in more-than-human geographies and within the discipline more widely, of the sea's inordinate agency and wider web of extraterrestrial relations are required in order to take seriously the often forgotten 70% of the Earth's surface which is ocean.
Voluntary Sector Organisations Working at the Neighbourhood Level in England: Patterns by Local Area Deprivation
Authors: Clifford David
Published: June 2012

Geographical variations in voluntary sector activity are important where they lead to inequity in service provision and differences in the opportunity to participate in voluntary group activities. However, despite important theoretical work, very little work has demonstrated variation empirically, particularly variation at the local (neighbourhood) level. This paper, for the first time, examines nationally representative data to illustrate the very real geographical differences across England in the prevalence of voluntary organisations working at a neighbourhood scale. Overall, less deprived local areas have a much higher prevalence than more deprived local areas. While certain kinds of organisations are more prevalent in more deprived areas, including those working in the field of economic well-being, this reflects the presence of organisations which receive public funds. These patterns are consistent with a key element of ‘voluntary sector failure’, resource insufficiency, and the important role of government in ensuring resources are available in areas of particular need.
Smart Growth and Urban Economic Development: Connecting Economic Development and Land-Use Planning Using the Example of High-Tech Firms
Authors: Wlodarczak Duncan
Published: June 2012

This paper explores the connections between economic development and sustainable land-use planning. It brings forward the idea that for cities to adapt their development patterns from low-density urban sprawl, they must plan and develop with efforts coordinated between economic development and land-use planning. It uses the example of the high-tech sector to determine what aspects are needed to create areas that are both attractive to high-tech firms while also matching the principles of smart growth, a popular method of sustainable urban development. It analyzes two case-study areas in Metro Vancouver: Yaletown, a dense neighbourhood in downtown Vancouver; and Crestwood Corporate Centre, a traditional office park in Richmond. Through these case studies the important factors needed to attract high-tech firms are determined, and connections with aspects of smart growth are articulated. It is argued that economic development and forms of sustainable urban development such as smart growth have positive connections and mutually beneficial results when coordinated.
The Good, the Bad, and the Hands-on: Constructs of Public Participation, Anglers, and Lay Management of Water Environments
Authors: Eden Sally , Bear Christopher
Published: June 2012

We use a qualitative study of recreational anglers in northern England to explore constructions of ‘the public’ in environmental management. We examine good and bad constructs of ‘the public’ and show how they emphasise knowledge over practice. We argue for a more differentiated view of the public through ‘environmental engagement’ which will appreciate more fully ways in which both ‘specialised publics’ and ‘performative publics’ are imagined and enacted. We demonstrate how these constructs play out through attending to the discursive and material ‘hands-on’ practices of anglers in environmental management and show how these link different geographies of public participation through both discursive and material spaces.
Policy Conflict and the Feasibility of Water Pollution Trading Programs in the Tai Lake Basin, China
Authors: Zhang Yongliang , Zhang Bing , Bi Jun
Published: June 2012

Water pollution trading (WPT) is considered a cost-effective policy instrument for controlling water pollution. Since the late 1990s the Chinese government has piloted WPT programs at different levels in an attempt to reduce water pollution. However, the implementation of WPT programs has not achieved the results expected. Policy overlap, or conflict, is thought to be one of main factors blocking the deployment of effective WPT projects in China. This research takes the WPT pilot program in the Tai Lake Basin as a case study to assess the problem of incoherent policies in this area and to explore the general feasibility of WPT programs in China. We review and analyze the water pollution control system in the Tai Lake Basin as well as the regulation and practices of the WPT Tai Lake pilot program. The results of this study indicate that the WPT program in the Tai Lake Basin conflicts fundamentally with other environmental regulation regimes, such as the Environmental Impact Assessment system and the Five-Year Plan target, and that the prospects for WPT in China are not optimistic. Finally, we outline suggestions for reforming China's WPT mechanism to eliminate these conflicts.