bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel structure for enhancing the sensitivity of gas sensors – α-Fe2O3 nanoropes containing a large amount of grain boundaries and their excellent ethanol sensing performance
Authors: Yan Shuang , Wu Qingsheng
Published: February 2015

α-Fe2O3 nanoropes were composed of well-ordered grain boundaries which work as effective amplifiers of resistance changes during gas sensing.
Electrospinning graphene quantum dots into a nanofibrous membrane for dual-purpose fluorescent and electrochemical biosensors
Authors: Zhang Panpan , Zhao Xinne , Ji Yuanchun , Ouyang Zhaofei , Wen Xin , Li Jingfeng , Su Zhiqiang , Wei Gang
Published: February 2015

An electrospinning technique was utilized to add graphene quantum dots into a nanofibrous polymer membrane for dual-purpose fluorescent and electrochemical biosensors.
“One-drop-of-blood” electroanalysis of lead levels in blood using a foam-like mesoporous polymer of melamine–formaldehyde and disposable screen-printed electrodes
Authors: Zhao Yanfang , Xu Lubin , Li Shuying , Chen Qi , Yang Daoshan , Chen Lingxin , Wang Hua
Published: February 2015

A foam-like mesoporous melamine–formaldehyde polymer was synthesized and deposited on disposable screen-printed electrodes for the electroanalysis of Pb2+ions in blood.
Ecofriendly synthesis of halogenated flavonoids and evaluation of their antifungal activity
Authors: Bernini Roberta , Pasqualetti Marcella , Provenzano Gianfranco , Tempesta Sabrina
Published: February 2015

Chlorinated catechin derivative 29 resulted in being the most active compound against Trichoderma koningii and Cladosporium cladosporioides, common saprotrophic soil and seed fungi.
Arginine-assisted synthesis of palladium nanochain networks and their enhanced electrocatalytic activity for borohydride oxidation
Authors: Fu Geng-Tao , Wu Rui , Liu Chang , Lin Jun , Sun Dong-Mei , Tang Ya-Wen
Published: February 2015

Three-dimensional Pd nanochain networks (Pd-NCNs) were prepared by an arginine-assisted self-assembly process, exhibiting excellent electrocatalytic performance towards the borohydride oxidation reaction.
Ultrathin porous nickel–cobalt hydroxide nanosheets for high-performance supercapacitor electrodes
Authors: Zheng Xiaoting , Gu Zhengxiang , Hu Qingqing , Geng Baoyou , Zhang Xiaojun
Published: February 2015

Ultrathin porous nickel–cobalt layered double hydroxide (Ni–Co LDH) hybrid nanosheets on metal nickel sheets shows highly electrochemical performance which synthesizing via a facile hydrothermal method without any adscititious surfactant.
Poly(phenylene oxide) functionalized with quaternary ammonium groups via flexible alkyl spacers for high-performance anion exchange membranes
Authors: Dang Hai-Son , Weiber Eva Annika , Jannasch Patric
Published: February 2015

Hydroxide ion conductivity and alkaline stability of anion exchange membranes were dramatically improved by placing quaternary ammonium groups on long alkyl side chains.
Differential six‐port reflectometer for determining dry rubber content of latex
Authors: Julrat Sakol , Chongcheawchamnan Mitchai , Robertson Ian D.
Published: February 2015

This study presents the application of a differential six‐port reflectometer to the design of a portable system for measurement of the dry rubber content (DRC) of latex. The proposed DRC measurement system consists of a 1 GHz reflectometer used with an open‐ended coaxial‐probe sensor, a temperature sensor, a display and a microcontroller. The complex permittivity and temperature of the rubber latex are measured, and a temperature‐dependent model for DRC determination based on a dielectric mixture theory is used. The reflectometer performance is verified by comparing the measured complex permittivity with the results obtained from a commercial dielectric measurement system. Finally, the accuracy of the DRC measurement system is assessed by comparing the measured DRCs from different latex samples over the range of 10–40°C with the standard oven‐drying method.
Q‐switched Brillouin fibre laser with multi‐wall carbon nanotube saturable absorber
Authors: Zarei Arman , Tiu Z. C. , Ahmad F. , Ahmad Harith , Harun Sulaiman Wadi
Published: February 2015

A Q‐switched Brillouin fibre laser (BFL) is successfully demonstrated using multi‐walled carbon nanotubes (MWCNTs) embedded in polyvinyl alcohol (PVA) film as a passive saturable absorber (SA) for the first time. The SA is obtained by sandwiching the developed MWCNTs–PVA film between two FC/PC fibre connectors after depositing index‐matching gel onto the fibre ends. The proposed Q‐switched BFL incorporates a 5 km long dispersion shifted fibre in a ring cavity structure to generate Stokes shifted by 0.08 nm from the Brillouin pump wavelength. The BFL starts to generate a Q‐switching pulse train at threshold pump power of 5 dBm. As the BP power is varied from 5.0 to 6.0 dBm, the repetition rate of the Q‐switched BFL exhibits an increasing trend from 27.75 to 30.21 kHz, whereas the pulse width exhibits a decreasing trend from 3.25 μs to 1.11 μs. The maximum pulse energy of 0.13 nJ is obtained at maximum BP power of 6.0 dBm.
Characterisation of Raman distributed temperature sensor using deconvolution algorithms
Authors: Pradhan Himansu Shekhar , Sahu Prasant Kumar
Published: February 2015

The behaviour of distributed temperature sensors based on spontaneous Raman scattering using deconvolution algorithm is studied for improvement of temperature and spatial resolution in Raman distributed temperature sensor (RDTS). The deconvolution algorithms such as Fourier deconvolution (FourD), Fourier regularised deconvolution and Fourier wavelet regularised deconvolution (FourWaRD) are investigated in this study. Numerical simulation shows that the temperature resolution is enhanced by six times using the proposed FourWaRD algorithm compared with conventional FourD algorithm. In this study, for a light source with 60 ns pulse width, a spatial resolution of 3 m is achieved using the FourWaRD algorithm. The proposed sensing system exhibits a temperature resolution of 0.45 K because of the reduction of noise. In addition, the signal to noise ratio (SNR) of proposed RDTS is realised using Indium Gallium Arsenide avalanche photo detector over a 30 km sensing range. The authors have achieved about 4 dB improvement of SNR using FourWaRD algorithm compared with FourD algorithm at a distance of 25 km for an input power of 10 dBm. The numerical simulation results indicate that the proposed deconvolution algorithms are beneficial complements for RDTS to realise accurate detection and temperature monitoring of sharp temperature variations.
Thermodynamic versus kinetic control in self-assembly of zero-, one-, quasi-two-, and two-dimensional metal-organic coordination structures
Authors: Lin Tao , Wu Qi , Liu Jun , Shi Ziliang , Liu Pei Nian , Lin Nian
Published: February 2015

Four types of metal-organic structures exhibiting specific dimensionality were studied using scanning tunneling microscopy and Monte Carlo simulations. The four structures were self-assembled out of specifically designed molecular building blocks via the same coordination motif on an Au(111) surface. We found that the four structures behaved differently in response to thermal annealing treatments: The two-dimensional structure was under thermodynamic control while the structures of lower dimension were under kinetic control. Monte Carlo simulations revealed that the self-assembly pathways of the four structures are associated with the characteristic features of their specific heat. These findings provide insights into how the dimensionality of supramolecular coordination structures affects their thermodynamic properties.
Positron accumulation effect in particles embedded in a low-density matrix
Authors: Dryzek Jerzy , Siemek Krzysztof
Published: February 2015

Systematic studies of the so-called positron accumulation effect for samples with particles embedded in a matrix are reported. This effect is related to energetic positrons which penetrate inhomogeneous medium. Due to differences in the linear absorption coefficient, different amounts of positrons are accumulated and annihilate in the identical volume of both materials. Positron lifetime spectroscopy and Doppler broadening of the annihilation line using Na-22 positrons were applied to the studies of the epoxy resin samples with embedded micro-sized particles of transition metals, i.e., Ni, Sn, Mo, W, and nonmetal particles, i.e., Si and NaF. The significant difference between the determined fraction of positrons annihilating in the particles and the particle volume fraction indicates the positron accumulation effect. The simple phenomenological model and Monte Carlo simulations are able to describe the main features of the obtained dependencies. The aluminum alloy with embedded Sn nanoparticles is also considered for demonstration differences between the accumulation and another related effect, i.e., the positron affinity.
The structural and magnetic properties of Pr1−xErxAl2
Authors: Pathak Arjun K. , Gschneidner K. A. , Pecharsky V. K.
Published: February 2015

We report on the effect of Er addition to PrAl2 on the lattice parameters, magnetic behavior, heat capacity, and magnetocaloric effect by using x-ray diffraction, magnetization, and heat capacity measurements. Unlike Pr0.6Er0.4Al2, other alloys we studied in the pseudobinary (Pr1−xErx)Al2 system do not exhibit a sharp peak in heat capacity with the application of magnetic field. Both the cubic lattice parameter and the Curie temperature decrease with increasing Er concentration. The nuclear specific heat coefficient decreases from 660 mJ K mol−1 for x = 0.05 to a nearly negligible value for x = 0.95. The magnetic entropy and adiabatic temperature change varies from 2 to 4 J mol−1 K−1 and 2.5 to 5 K at ΔH = 20 kOe for x = 0.05 to 0.95, respectively. These values of the magnetocaloric effect are comparable to those of the other rare-earth dialuminides systems.
A comparison of neutral and charged species of one- and two-dimensional models of graphene nanoribbons using multireference theory
Authors: Horn Shawn , Lischka Hans
Published: February 2015

This study examines the dependence of the polyradical character of charged quasi-linear n-acenes and two-dimensional periacenes used as models for graphene nanoribbons in comparison to the corresponding neutral compounds. For this purpose, high-level ab initio calculations have been performed using the multireference averaged quadratic coupled cluster theory. Vertical ionization energies and electron affinities have been computed. Systematic tests show that the dependence on chain length of these quantities can be obtained from a consideration of the π system only and that remaining contributions coming from the σ orbitals or extended basis sets remain fairly constant. Using best estimate values, the experimental values for the ionization energy of the acene series can be reproduced within 0.1 eV and the experimental electron affinities within 0.4 V. The analysis of the natural orbital occupations and related unpaired electron densities shows that the ionic species exhibit a significant decrease in polyradical character and thus an increased chemical stability as compared to the neutral state.
Decomposition of DyF3 and its effect on magnetic performance of DyF3-doped Nd-Fe-B-type hot-deformed magnet
Authors: Kim J. Y. , Kwon H. W. , Lee J. G. , Yu J. H.
Published: February 2015

Decomposition of DyF3 and its effect on the magnetic performance of the hot-pressed compact and die-upset magnet of melt-spun Nd-Fe-B-type material were investigated. DyF3 was thermally decomposed above 660 °C, and this decomposition was linked closely to the coercivity enhancement. When the DyF3 doped flakes were hot-pressed above the decomposition temperature of DyF3, the diffusion of Dy into the flakes was promoted, and leading to profound coercivity enhancement. Coercivity of the hot-pressed magnet was further enhanced by post-hot-press annealing, and coercivity as high as 24.5 kOe was obtained after the optimum annealing. The DyF3 doped hot-deformed magnet exhibited enhanced magnetic performance (iHc = 17.5 kOe, Br = 12.8 kG, (BH)max = 37.6 MGOe) with respect to the un-doped magnet without sacrificing significant remanence. Coercivity was improved by 30%. In magnet in which the decomposition of DyF3 and Dy diffusion were fully accomplished, the region originally occupied by added DyF3 was completely replaced by NdF3.
Velocity profiles of electric-field-induced backflows in liquid crystals confined between parallel plates
Authors: Tsuji Tomohiro , Chono Shigeomi , Matsumi Takanori
Published: February 2015

For the purpose of developing liquid crystalline microactuators, we visualize backflows induced between two parallel plates for various parameters such as the twist angle, cell gap, applied voltage, and molecular configuration mode. We use 4-cyano-4′-pentyl biphenyl, a typical low-molar-mass nematic liquid crystal. By increasing the twist angle from 0° to 180°, the velocity component parallel to the anchoring direction of the lower plate changes from an S-shaped profile to a distorted S-shaped profile before finally becoming unidirectional. In contrast, the velocity component perpendicular to the anchoring direction evolves from a flat profile at 0° into an S-shaped profile at 180°. Because both an increase in the applied voltage and a decrease in the cell gap increase the electric field intensity, the backflow becomes large. The hybrid molecular configuration mode induces a larger backflow than that for the planar aligned mode. The backflow develops in two stages: an early stage with a microsecond time scale and a later stage with a millisecond time scale. The numerical predictions are in qualitative agreement with the measurements, but not quantitative agreement because our computation ignores the plate edge effect of surface tension.
Effects of spin diffusion on electron spin relaxation time measured with a time-resolved microscopic photoluminescence technique
Authors: Ikeda Kazuhiro , Kawaguchi Hitoshi
Published: February 2015

We performed measurements at room temperature for a GaAs/AlGaAs multiple quantum well grown on GaAs(110) using a time-resolved microscopic photoluminescence (micro-PL) technique to find what effects spin diffusion had on the measured electron spin relaxation time, τs, and developed a method of estimating the spin diffusion coefficient, Ds, using the measured data and the coupled drift-diffusion equations for spin polarized electrons. The spatial nonuniformities of τs and the initial degree of electron spin polarization caused by the pump intensity distribution inside the focal spot were taken into account to explain the dependence of τs on the measured spot size, i.e., a longer τs for a smaller spot size. We estimated Ds as ∼100 cm2/s, which is similar to a value reported in the literature. We also provided a qualitative understanding on how spin diffusion lengthens τs in micro-PL measurements.
Modulating action of low frequency oscillations on high frequency instabilities in Hall thrusters
Authors: Liqiu Wei , Liang Han , Ziyi Yang , Jing Li , Yong Cao , Daren Yu , Jianhua Du
Published: February 2015

It is found that the low frequency oscillations have modulating action on high frequency instabilities in Hall thrusters. The physical mechanism of this modulation is discussed and verified by numerical simulations. Theoretical analyses indicate that the wide-range fluctuations of plasma density and electric field associated with the low frequency oscillations affect the electron drift velocity and anomalous electron transport across the magnetic field. The amplitude and frequency of high frequency oscillations are modulated by low frequency oscillations, which show the periodic variation in the time scale of low frequency oscillations.
Magnetic frustration and dielectric relaxation in insulating Nd2NiMnO6 double perovskites
Authors: Yadav Ruchika , Elizabeth Suja
Published: February 2015

We have investigated structural, dielectric, and magnetic properties of polycrystalline double perovskite Nd2NiMnO6 compound. The compound crystallizes in monoclinic P21∕n symmetry and is partially B-site disordered depending on the synthesis conditions. It undergoes second-order ferromagnetic transition at 192 K and shows glassy behaviour at low temperature. The glassy phase is due to anti-site disorder within the homogeneous sample. Temperature and frequency dependent dielectric measurements reveal colossal values of dielectric constant and is best interpreted using Maxwell-Wagner interfacial polarization model. Impedance spectroscopy has been used to analyse the intrinsic dielectric response. This enabled us to differentiate the conduction process at the grain and grain boundaries. Arrhenius behaviour is favoured at the grain boundary, while variable range hopping mechanism is considered most suitable within the grain region. dc conductivity measurements corroborate variable range hopping conduction.
Solid phase stability of molybdenum under compression: Sound velocity measurements and first-principles calculations
Authors: Zhang Xiulu , Liu Zhongli , Jin Ke , Xi Feng , Yu Yuying , Tan Ye , Dai Chengda , Cai Lingcang
Published: February 2015

The high-pressure solid phase stability of molybdenum (Mo) has been the center of a long-standing controversy on its high-pressure melting. In this work, experimental and theoretical researches have been conducted to check its solid phase stability under compression. First, we performed sound velocity measurements from 38 to 160 GPa using the two-stage light gas gun and explosive loading in backward- and forward-impact geometries, along with the high-precision velocity interferometry. From the sound velocities, we found no solid-solid phase transition in Mo before shock melting, which does not support the previous solid-solid phase transition conclusion inferred from the sharp drops of the longitudinal sound velocity [Hixson et al., Phys. Rev. Lett. 62, 637 (1989)]. Then, we searched its structures globally using the multi-algorithm collaborative crystal structure prediction technique combined with the density functional theory. By comparing the enthalpies of body centered cubic structure with those of the metastable structures, we found that bcc is the most stable structure in the range of 0–300 GPa. The present theoretical results together with previous ones greatly support our experimental conclusions.
Hydrodynamic limit of Wigner-Poisson kinetic theory: Revisited
Authors: Akbari-Moghanjoughi M.
Published: February 2015

In this paper, we revisit the hydrodynamic limit of the Langmuir wave dispersion relation based on the Wigner-Poisson model in connection with that obtained directly from the original Lindhard dielectric function based on the random-phase-approximation. It is observed that the (fourth-order) expansion of the exact Lindhard dielectric constant correctly reduces to the hydrodynamic dispersion relation with an additional term of fourth-order, beside that caused by the quantum diffraction effect. It is also revealed that the generalized Lindhard dielectric theory accounts for the recently discovered Shukla-Eliasson attractive potential (SEAP). However, the expansion of the exact Lindhard static dielectric function leads to a k4 term of different magnitude than that obtained from the linearized quantum hydrodynamics model. It is shown that a correction factor of 1/9 should be included in the term arising from the quantum Bohm potential of the momentum balance equation in fluid model in order for a correct plasma dielectric response treatment. Finally, it is observed that the long-range oscillatory screening potential (Friedel oscillations) of type cos(2kFr)/r3, which is a consequence of the divergence of the dielectric function at point k = 2kF in a quantum plasma, arises due to the finiteness of the Fermi-wavenumber and is smeared out in the limit of very high electron number-densities, typical of white dwarfs and neutron stars. In the very low electron number-density regime, typical of semiconductors and metals, where the Friedel oscillation wavelength becomes much larger compared to the interparticle distances, the SEAP appears with a much deeper potential valley. It is remarked that the fourth-order approximate Lindhard dielectric constant approaches that of the linearized quantum hydrodynamic in the limit if very high electron number-density. By evaluation of the imaginary part of the Lindhard dielectric function, it is shown that the Landau-damping region in ω-k plane increases dramatically by increase of the electron number-density.
Local geometric and electronic structures and origin of magnetism in Co-doped BaTiO3 multiferroics
Authors: Phan The-Long , Thang P. D. , Ho T. A. , Manh T. V. , Thanh Tran Dang , Lam V. D. , Dang N. T. , Yu S. C.
Published: February 2015

We have prepared polycrystalline samples BaTi1−xCoxO3 (x = 0–0.1) by solid-state reaction. X-ray diffraction and Raman-scattering studies reveal the phase separation in crystal structure as changing Co-doping content (x). The samples with x = 0–0.01 are single phase in a tetragonal structure. At higher doping contents (x > 0.01), there is the formation and development of a secondary hexagonal phase. Magnetization measurements at room temperature indicate a coexistence of paramagnetic and weak-ferromagnetic behaviors in BaTi1−xCoxO3 samples with x > 0, while pure BaTiO3 is diamagnetic. Both these properties increase with increasing x. Analyses of X-ray absorption spectra recorded from BaTi1−xCoxO3 for the Co and Ti K-edges indicate the presence of Co2+ and Co3+ ions. They locate in the Ti4+ site of the tetragonal and hexagonal BaTiO3 structures. Particularly, there is a shift of oxidation state from Co2+ to Co3+ when Co-doping content increases. We believe that the paramagnetic nature in BaTi1−xCoxO3 samples is due to isolated Co2+ and Co3+ centers. The addition of Co3+ ions enhances the paramagnetic behavior. Meanwhile, the origin of ferromagnetism is due to lattice defects, which is less influenced by the changes caused by the variation in concentration of Co2+ and Co3+ ions.
Evidence of locally enhanced target heating due to instabilities of counter-streaming fast electron beams
Authors: Koester Petra , Booth Nicola , Cecchetti Carlo A. , Chen Hui , Evans Roger G. , Gregori Gianluca , Labate Luca , Levato Tadzio , Li Bin , Makita Mikako , Mithen James , Murphy Christopher D. , Notley Margaret , Pattathil Rajeev , Riley David , Woolsey Nigel , Gizzi Leonida A.
Published: February 2015

The high-current fast electron beams generated in high-intensity laser-solid interactions require the onset of a balancing return current in order to propagate in the target material. Such a system of counter-streaming electron currents is unstable to a variety of instabilities such as the current-filamentation instability and the two-stream instability. An experimental study aimed at investigating the role of instabilities in a system of symmetrical counter-propagating fast electron beams is presented here for the first time. The fast electron beams are generated by double-sided laser-irradiation of a layered target foil at laser intensities above 1019 W/cm2. High-resolution X-ray spectroscopy of the emission from the central Ti layer shows that locally enhanced energy deposition is indeed achieved in the case of counter-propagating fast electron beams.
Drift effects on electromagnetic geodesic acoustic modes
Authors: Sgalla R. J. F.
Published: February 2015

A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the f ∼ 40 kHz oscillation observed in tokamak TCABR [Yu. K. Kuznetsov et al., Nucl. Fusion 52, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is λr ∼ 25 cm, i.e., an order of magnitude higher than the usual value for zonal flows (ZFs).
Halo formation and emittance growth in the transport of spherically symmetric mismatched bunched beams
Authors: Corrêa da Silva Thales M. , Pakter Renato , Rizzato Felipe B. , Levin Yan
Published: February 2015

The effect of an initial envelope mismatch on the transport of bunched spherically symmetric beams is investigated. A particle-core model is used to estimate the maximum radius that halo particles can reach. The theory is used to obtain an empirical formula that provides the halo size as a function of system parameters. Taking into account, the incompressibility property of the Vlasov dynamics and the resulting Landau damping, an explicit form for the final stationary distribution attained by the beam is proposed. The distribution is fully self-consistent, presenting no free fitting parameters. The theory is used to predict the relevant beam transport properties, such as the final particle density distribution, the emittance growth, and the fraction of particles that will be expelled to form halo. The theoretical results are compared to the explicit N-particle dynamics simulations, showing a good agreement.
Atomic packing and diffusion in Fe85Si2B9P4 amorphous alloy analyzed by ab initio molecular dynamics simulation
Authors: Wang Yaocen , Takeuchi Akira , Makino Akihiro , Liang Yunye , Kawazoe Yoshiyuki
Published: February 2015

In the work reported in this paper, ab initio molecular dynamics simulation was performed on Fe85Si2B9P4 amorphous alloy. Preferred atomic environment of the elements was analyzed with Voronoi polyhedrons. It showed that B and P atoms prefer less neighbors compared with Fe and Si, making them structurally incompatible with Fe rich structure and repulsive to the formation of α-Fe. However, due to the low bonding energy of B and P caused by low coordination number, the diffusion rates of them were considerably large, resulting in the requirement of fast annealing for achieving optimum nano-crystallization for its soft magnetic property. The simulation work also indicates that diffusion rate in amorphous alloy is largely determined by bonding energy rather than atomic size.
Influence of growth conditions on exchange bias of NiMn-based spin valves
Authors: Wienecke Anja , Kruppe Rahel , Rissing Lutz
Published: February 2015

As shown in previous investigations, a correlation between a NiMn-based spin valve's thermal stability and its inherent exchange bias exists, even if the blocking temperature of the antiferromagnet is clearly above the heating temperature and the reason for thermal degradation is mainly diffusion and not the loss of exchange bias. Samples with high exchange bias are thermally more stable than samples with low exchange bias. Those structures promoting a high exchange bias are seemingly the same suppressing thermally induced diffusion processes (A. Wienecke and L. Rissing, “Relationship between thermal stability and layer-stack/structure of NiMn-based GMR systems,” in IEEE Transaction on Magnetic Conference (EMSA 2014)). Many investigations were carried out on the influence of the sputtering parameters as well as the layer thickness on the magnetoresistive effect. The influence of these parameters on the exchange bias and the sample's thermal stability, respectively, was hardly taken into account. The investigation described here concentrates on the last named issue. The focus lies on the influence of the sputtering parameters and layer thickness of the “starting layers” in the stack and the layers forming the (synthetic) antiferromagnet. This paper includes a guideline for the evaluated sputtering conditions and layer thicknesses to realize a high exchange bias and presumably good thermal stability for NiMn-based spin valves with a synthetic antiferromagnet.
Two-dimensional electromagnetic quantum-hydrodynamic simulations of isochoric heating of a solid target by proton beams
Authors: Zhang Ya , Jiang Wei , Song Yuan-Hong , Wang You-Nian
Published: February 2015

Isochoric heating of an aluminum target by proton beams has been studied with a two-dimensional self-consistent electromagnetic quantum-hydrodynamic model, including the nonlinear quantum effects. It is shown that most protons deposit their energy within several micrometers near the surface, and the aluminum metal target is heated up to several electron volts in tens of Mbar pressure regime within one picosecond. Comparison between electrostatic and electromagnetic cases shows that the strength of electromagnetic field is much smaller than that of the electrostatic field at initial stage but increases more rapidly and becomes larger at later time. The results show that the time evolution of electric field has a significant influence on the interaction of intense beams with a solid target, while the effect of the self-magnetic field is small for non-relativistic beams considered here.
Current-voltage characteristics of dc corona discharges in air between coaxial cylinders
Authors: Zheng Yuesheng , Zhang Bo , He Jinliang
Published: February 2015

This paper presents the experimental measurement and numerical analysis of the current-voltage characteristics of dc corona discharges in air between coaxial cylinders. The current-voltage characteristics for both positive and negative corona discharges were measured within a specially designed corona cage. Then the measured results were fitted by different empirical formulae and analyzed by the fluid model. The current-voltage characteristics between coaxial cylinders can be expressed as I = C(U − U0)m, where m is within the range 1.5–2.0, which is similar to the point-plane electrode system. The ionization region has no significant effect on the current-voltage characteristic under a low corona current, while it will affect the distribution for the negative corona under a high corona current. The surface onset fields and ion mobilities were emphatically discussed.
Enhanced thermoelectric performance of nanostructured topological insulator Bi2Se3
Authors: Sun G. L. , Li L. L. , Qin X. Y. , Li D. , Zou T. H. , Xin H. X. , Ren B. J. , Zhang J. , Li Y. Y. , Li X. J.
Published: February 2015

To enhance thermoelectric performance by utilizing topological properties of topological insulators has attracted increasing attention. Here, we show that as grain size decreases from microns to ∼80 nm in thickness, the electron mobility μ increases steeply from 12–15 cm2 V−1 s−1 to ∼600 cm2 V−1 s−1, owing to the contribution of increased topologically protected conducting surfaces. Simultaneously, its lattice thermal conductivity is lowered by ∼30%–50% due to enhanced phonon scattering from the increased grain boundaries. As a result, thermoelectric figure of merit, ZT, of all the fine-grained samples is improved. Specifically, a maximum value of ZT = ∼0.63 is achieved for Bi2Se3 at T = ∼570 K.
Electronic desalting for controlling the ionic environment in droplet-based biosensing platforms
Authors: Swaminathan Vikhram Vilasur , Dak Piyush , Reddy Bobby , Salm Eric , Duarte-Guevara Carlos , Zhong Yu , Fischer Andrew , Liu Yi-Shao , Alam Muhammad A. , Bashir Rashid
Published: February 2015

The ability to control the ionic environment in saline waters and aqueous electrolytes is useful for desalination as well as electronic biosensing. We demonstrate a method of electronic desalting at micro-scale through on-chip micro electrodes. We show that, while desalting is limited in bulk solutions with unlimited availability of salts, significant desalting of ≥1 mM solutions can be achieved in sub-nanoliter volume droplets with diameters of ∼250 μm. Within these droplets, by using platinum-black microelectrodes and electrochemical surface treatments, we can enhance the electrode surface area to achieve >99% and 41% salt removal in 1 mM and 10 mM salt concentrations, respectively. Through self-consistent simulations and experimental measurements, we demonstrate that conventional double-layer theory over-predicts the desalting capacity and, hence, cannot be used to model systems that are mass limited or undergoing significant salt removal from the bulk. Our results will provide a better understanding of capacitive desalination, as well as a method for salt manipulation in high-throughput droplet-based microfluidic sensing platforms.
First principles calculation on the magnetic, optical properties and oxygen vacancy effect of CexY3−xFe5O12
Authors: Liang Xiao , Xie Jianliang , Deng Longjiang , Bi Lei
Published: February 2015

We report a first principles study on the magnetic and optical properties of Ce substituted yttrium iron garnet (CexY3−xFe5O12) (Ce:YIG) (x = 0.125, 0.25, 0.5, and 1.0). Using density functional theory with Hubbard-U corrections, we demonstrate that Ce3+-Fe3+(tetrahedral) charge transfer is the dominating mechanism of enhanced near infrared absorption in Ce:YIG. In particular, oxygen vacancies are found to be able to stabilize Ce3+ from converting to Ce4+, at the same time reduce two neighboring Fe3+ to Fe2+ which occupy both the octahedral and tetrahedral sites. The formation enthalpy of Ce4+-Fe2+ state is strongly dependent on the distance from the Ce ion to the oxygen vacancy, which is closely related to the local lattice distortion around the Ce ion. This result provides theoretical insight for developing high figure of merit magneto-optical materials for nonreciprocal photonic applications.
Acoustic superlens using membrane-based metamaterials
Authors: Park Jong Jin , Park Choon Mahn , Lee K. J. B. , Lee Sam H.
Published: February 2015

We report construction of an acoustic superlensing using two dimensional membrane-based negative-density metamaterials. When two point sources separated by a distance of 1/17 of the wavelength are placed near to a surface of the metamaterial slab, well-resolved images are formed on the opposite surface across the slab. The mechanism for the subwavelength resolution is the surface wave stemming from negative density. Potential applications include acoustic imaging and sensing.
The Piano-Industry Workforce in Mid-Victorian England: a Study of the 1881 Census
Authors: Kent Marie
Published: February 2015

The identification of nearly 6,500 members of the piano industry in the 1881 census of England presents the first ‘snapshot’ of the English workforce of any period in its history. Traditionally, research has focused on high-profile makers whose workmanship survives, but many hundreds of workers, and a far greater body of intellect – and more diverse body of labour – were involved in advancing the piano than that which is suggested by a small number of luminaries working in the capital. Yet hitherto, with few exceptions, this wider body of workers has remained anonymous. Without company documents or extant instruments to mark their contribution, the identity of the majority of the workforce might only be known through the census. Nearly 6,500 men, women and children worked in approximately 400 piano-related occupations across 42 English counties, the majority based in London. But these figures tell only part of the story. A more complex interpretation may be drawn from secondary information not immediately apparent from the data. The social standing, entrepreneurial spirit, family history, success and hardship of the workforce may all be appraised via the census, and their individual and collective careers provide a surprising insight into the piano-making industry in mid-Victorian England.
Perlecan is recruited by dystroglycan to nodes of Ranvier and binds the clustering molecule gliomedin
Authors: Colombelli Cristina , Palmisano Marilena , Eshed-Eisenbach Yael , Zambroni Desirée , Pavoni Ernesto , Ferri Cinzia , Saccucci Stefania , Nicole Sophie , Soininen Raija , McKee Karen K. , Yurchenco Peter D. , Peles Elior , Wrabetz Lawrence , Feltri M. Laura
Published: February 2015

Fast neural conduction requires accumulation of Na+ channels at nodes of Ranvier. Dedicated adhesion molecules on myelinating cells and axons govern node organization. Among those, specific laminins and dystroglycan complexes contribute to Na+ channel clustering at peripheral nodes by unknown mechanisms. We show that in addition to facing the basal lamina, dystroglycan is found near the nodal matrix around axons, binds matrix components, and participates in initial events of nodogenesis. We identify the dystroglycan-ligand perlecan as a novel nodal component and show that dystroglycan is required for the selective accumulation of perlecan at nodes. Perlecan binds the clustering molecule gliomedin and enhances clustering of node of Ranvier components. These data show that proteoglycans have specific roles in peripheral nodes and indicate that peripheral and central axons use similar strategies but different molecules to form nodes of Ranvier. Further, our data indicate that dystroglycan binds free matrix that is not organized in a basal lamina.
Structural basis for assembly and function of the Nup82 complex in the nuclear pore scaffold
Authors: Gaik Monika , Flemming Dirk , von Appen Alexander , Kastritis Panagiotis , Mücke Norbert , Fischer Jessica , Stelter Philipp , Ori Alessandro , Bui Khanh Huy , Baßler Jochen , Barbar Elisar , Beck Martin , Hurt Ed
Published: February 2015

Nuclear pore complexes (NPCs) are huge assemblies formed from ∼30 different nucleoporins, typically organized in subcomplexes. One module, the conserved Nup82 complex at the cytoplasmic face of NPCs, is crucial to terminate mRNA export. To gain insight into the structure, assembly, and function of the cytoplasmic pore filaments, we reconstituted in yeast the Nup82–Nup159–Nsp1–Dyn2 complex, which was suitable for biochemical, biophysical, and electron microscopy analyses. Our integrative approach revealed that the yeast Nup82 complex forms an unusual asymmetric structure with a dimeric array of subunits. Based on all these data, we developed a three-dimensional structural model of the Nup82 complex that depicts how this module might be anchored to the NPC scaffold and concomitantly can interact with the soluble nucleocytoplasmic transport machinery.
Arginine Metabolic Endotypes in Pulmonary Arterial Hypertension
Authors: Kao Christina C. , Wedes Samuel H. , Hsu Jean W. , Bohren Kurt M. , Comhair Suzy A. A. , Jahoor Farook , Erzurum Serpil C.
Published: February 2015

Decreased synthesis of nitric oxide (NO) by NO synthases (NOS) is believed to play an important role in the pathogenesis of pulmonary arterial hypertension (PAH). Multiple factors may contribute to decreased NO bioavailability, including increased activity of arginase, the enzyme that converts arginine to ornithine and urea, which may compete with NOS for arginine; inadequate de novo arginine production from citrulline; and increased concentration of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NOS. We hypothesized that PAH patients with the lowest arginine availability secondary to increased arginase activity and/or inadequate de novo arginine synthesis might have a slower rate of NO synthesis and greater pulmonary vascular resistance. Nine patients with group 1 PAH and 10 healthy controls were given primed, constant intravenous infusions of 15N2‐arginine, 13C,2H4‐citrulline, 15N2‐ornithine, and 13C‐urea in the postabsorptive state. The results showed that, compared with healthy controls, PAH patients had a tendency toward increased arginine clearance and ornithine flux but no difference in arginine and citrulline flux, de novo arginine synthesis, or NO synthesis. Arginine‐to‐ADMA ratio was increased in PAH patients. Two endotypes of patients with low and high arginase activity were identified; compared with the low‐arginase group, the patients with high arginase had increased arginine flux, slower NO synthesis, and lower plasma concentrations of ADMA. These results demonstrate that increased breakdown of arginine by arginase occurs in PAH and affects NO synthesis. Furthermore, there is no compensatory increase in de novo arginine synthesis to overcome this increased utilization of arginine by arginase.
Optical dual-band photometry and spectroscopy of the WZ Sge-type dwarf nova EZ Lyn during the 2010 superoutburst
Authors: Isogai Mizuki , Arai Akira , Yonehara Atsunori , Kawakita Hideyo , Uemura Makoto , Nogami Daisaku
Published: February 2015

We performed optical simultaneous dual-band (SDSS $g^{\kern1.5pt\prime}$- and i ′-bands) photometry and low-resolution spectroscopy for the WZ Sge-type dwarf nova EZ Lyn during its 2010 superoutburst. Dual-band photometry revealed that the $g^{\kern1.5pt\prime} - i^{\prime}$ color reddened with a decrease in brightness during the main superoutburst and the following rebrightening phase, whereas the color became bluer with a further decrease in brightness during the slow, final decline phase. With a fit to our photometric results by a blackbody function, we estimated the disk radius ratio (ratio of the disk radius to the binary separation) and compared this with that of V455 And, a WZ Sge-type object that did not show any rebrightening in the 2007 superoutburst. The comparison revealed: (1) the disk radius ratio of EZ Lyn decreased more slowly than that of V455 And, and (2) the radius ratio of EZ Lyn at the end of the main superoutburst was larger than that of V455 And. These results favor the mass reservoir model for the mechanism of rebrightening. During both the superoutburst plateau and subsequent rebrightening phase, Hα and Hβ lines were detected. The Hα line showed a double-peak profile from which we estimated the disk radius ratio. The comparison of this ratio with that derived by photometry indicates that the Hα disk was larger than the photometric one, which suggests that the optically thin gas was extended to the outer region more than the optically thick gas disk and was possibly responsible for the rebrightening phenomenon. Time-series dual-band photometry during the main superoutburst revealed that color variations during the early superhump show roughly the same behavior as that of V455 And, whereas color variations during the ordinary superhump display clear anticorrelation with brightness, in contrast to that seen in V455 And. Here, we discuss different color behaviors.
Suzaku studies of the supernova remnant CTB 109 hosting the magnetar 1E 2259+586
Authors: Nakano Toshio , Murakami Hiroaki , Makishima Kazuo , Hiraga Junoko S. , Uchiyama Hideki , Kaneda Hidehiro , Enoto Teruaki
Published: February 2015

Ages of the magnetar 1E 2259+586 and the associated supernova remnant CTB 109 were studied. Analyzing the Suzaku data of CTB 109, its age was estimated to be ∼ 14 kyr, which is much younger than the measured characteristic age of 1E 2259+586, 230 kyr. This reconfirms the previously reported age discrepancy of this magnetar/remnant association, and suggests that the characteristic ages of magnetars are generally over-estimated as compared to their true ages. This discrepancy is thought to arise because the former are calculated without considering decay of the magnetic fields. This novel view is supported independently by much stronger Galactic-plane concentration of magnetars than other pulsars. The process of magnetic field decay in magnetars is mathematically modeled. It is implied that magnetars are much younger objects than previously considered, and can dominate new-born neutron stars.
Lamins at the crossroads of mechanosignaling
Authors: Osmanagic-Myers Selma , Dechat Thomas , Foisner Roland
Published: February 2015

The intermediate filament proteins, A- and B-type lamins, form the nuclear lamina scaffold adjacent to the inner nuclear membrane. B-type lamins confer elasticity, while A-type lamins lend viscosity and stiffness to nuclei. Lamins also contribute to chromatin regulation and various signaling pathways affecting gene expression. The mechanical roles of lamins and their functions in gene regulation are often viewed as independent activities, but recent findings suggest a highly cross-linked and interdependent regulation of these different functions, particularly in mechanosignaling. In this newly emerging concept, lamins act as a “mechanostat” that senses forces from outside and responds to tension by reinforcing the cytoskeleton and the extracellular matrix. A-type lamins, emerin, and the linker of the nucleoskeleton and cytoskeleton (LINC) complex directly transmit forces from the extracellular matrix into the nucleus. These mechanical forces lead to changes in the molecular structure, modification, and assembly state of A-type lamins. This in turn activates a tension-induced “inside-out signaling” through which the nucleus feeds back to the cytoskeleton and the extracellular matrix to balance outside and inside forces. These functions regulate differentiation and may be impaired in lamin-linked diseases, leading to cellular phenotypes, particularly in mechanical load-bearing tissues.
Total Cellular Ca2+ Measurements in Yeast Using Flame Photometry
Authors: Tisi Renata , Martegani Enzo , Brandão Rogelio L.
Published: February 2015

A photoelectric flame photometer is a device used in inorganic chemical analysis for determining the concentrations of certain metals in solution. It does this by measuring the intensity of the light emitted by the metal when the solution is sprayed under controlled conditions into a nonluminous flame. This protocol describes how to measure total cellular calcium (maximal emission at 622 nm, orange flame) in yeast using this technique.
Charge distribution as a tool to investigate structural details. III. Extension to description in terms of anion-centred polyhedra
Authors: Eon Jean-Guillaume , Nespolo Massimo
Published: February 2015

The charge distribution (CHARDI) method is a self-consistent generalization of Pauling's concept of bond strength which does not make use of empirical parameters but exploits the experimental geometry of the coordination polyhedra building a crystal structure. In the two previous articles of this series [Nespoloet al.(1999).Acta Cryst.B55, 902–916; Nespoloet al.(2001).Acta Cryst.B57, 652–664], we have presented the features and advantages of this approach and its extension to distorted and heterovalent polyhedra and to hydrogen bonds. In this third article we generalize CHARDI to structures based on anion-centred polyhedra, which have drawn attention in recent years, and we show that computations based on both descriptions can be useful to obtain a deeper insight into the structural details, in particular for mixed-valence compounds where CHARDI is able to give precise indications on the statistical distribution of atoms with different oxidation number. A graph-theoretical description of the structures rationalizes and gives further support to the conclusions obtainedviathe CHARDI approach.
Calcium tartrate esahydrate, CaC4H4O6·6H2O: a structural and spectroscopic study
Authors: Ventruti Gennaro , Scordari Fernando , Bellatreccia Fabio , Della Ventura Giancarlo , Sodo Armida
Published: February 2015

The crystal structure of calcium tartrate esahydrate, CaC4H4O6·6H2O, has been solved by the charge-flipping method from single-crystal X-ray diffraction data and refined toR= 0.021, based on 1700 unique observed diffractions. Salient crystallographic data are:a= 7.7390 (1),b= 12.8030 (2),c= 5.8290 (1) Å,Z= 2, and space groupP21212. During the refinement step it was possible to locate all H atoms by difference Fourier synthesis. The tartrate molecule has a (−)-gaucheconformation and is coordinated to two calcium ions to form infinite chains along theaaxis which alternate Ca polyhedra with tartrate molecules. The chains are interlinked by a three-dimensional network of hydrogen bonds from four water molecules surrounding the Ca ion, reinforced by hydrogen bonds from one interstitial water molecule. Micro-Raman and FT–IR spectroscopic data are provided.