bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced electrocatalytic activity of the Au-electrodeposited Pt nanoparticles-coated conducting oxide for the quantum dot-sensitized solar cells
Authors: Yoon Yeung-Pil , Kim Jae-Hong , Kang Soon-Hyung , Kim Hyunsoo , Choi Chel-Jong , Kim Kyong-Kook , Ahn Kwang-Soon
Published: August 2014

Au was electrodeposited potentiostatically at 0.3 V for 5 min on nanoporous Pt nanoparticle-coated F-doped SnO2 (FTO/Pt) substrates. For comparison, Au-electrodeposited FTO (FTO/Au) and Au-uncoated FTO/Pt were prepared. FTO/Au showed large-sized Au clusters dispersed sparsely over FTO, which resulted in lower electrocatalytic activity than FTO/Pt. In contrast, FTO/Pt exhibited poor stability unlike FTO/Au due to poisoning by the adsorption of sulfur species. The Au-electrodeposited FTO/Pt (FTO/Pt/Au) consisted of small Au clusters deposited over the entire area of Pt due to the effective Au nucleation provided by nanoporous metallic Pt. FTO/Pt/Au exhibited enhanced electrocatalytic activity and excellent stability because the small Au particles well-dispersed over the nanoporous metallic Pt network provided numerous electrochemical reaction sites, and the Pt surface was not exposed to the electrolyte. When FTO/Pt/Au was used as the counter electrode (CE) of a quantum dot-sensitized solar cell, the significantly enhanced electrocatalytic activity of the FTO/Pt/Au CE facilitated the reduction reaction of Sn2− + 2e− (CE) → Sn−12− + S2− at the CE/electrolyte interface, resulting in a significantly hindered recombination reaction, Sn2− + 2e− (TiO2 in the photoanode) → Sn-12− + S2−, and significantly improved overall energy conversion efficiency.
Proximity nanovalve with large phase-tunable thermal conductance
Authors: Strambini E. , Bergeret F. S. , Giazotto F.
Published: August 2014

We propose a phase-controlled heat-flux quantum valve based on the proximity effect driven by a superconducting quantum interference proximity transistor (SQUIPT). Its operation relies on the phase-dependent quasiparticle density of states in the Josephson weak-link of the SQUIPT which controls thermal transport across the device. In a realistic Al/Cu-based setup the structure can provide efficient control of thermal current inducing temperature swings exceeding ∼100 mK, and flux-to-temperature transfer coefficients up to ∼500 mK/Φ0 below 100 mK. The nanovalve performances improve by lowering the bath temperature, making the proposed structure a promising building-block for the implementation of coherent caloritronic devices operating below 1 K.
Phase sensitive molecular dynamics of self-assembly glycolipid thin films: A dielectric spectroscopy investigation
Authors: Velayutham T. S. , Ng B. K. , Gan W. C. , Majid W. H. Abd. , Hashim R. , Zahid N. I. , Chaiprapa Jitrin
Published: August 2014

Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assemble without the presence of a solvent. Here, the dielectric and conductivity properties of three synthetic glycolipid thin films in different thermotropic liquid crystal phases were investigated over a frequency and temperature range of (10−2–106 Hz) and (303–463 K), respectively. The observed relaxation processes distinguish between the different phases (smectic A, columnar/hexagonal, and bicontinuous cubic Q) and the glycolipid molecular structures. Large dielectric responses were observed in the columnar and bicontinuous cubic phases of the longer branched alkyl chain glycolipids. Glycolipids with the shortest branched alkyl chain experience the most restricted self-assembly dynamic process over the broad temperature range studied compared to the longer ones. A high frequency dielectric absorption (Process I) was observed in all samples. This is related to the dynamics of the hydrogen bond network from the sugar group. An additional low-frequency mechanism (Process II) with a large dielectric strength was observed due to the internal dynamics of the self-assembly organization. Phase sensitive domain heterogeneity in the bicontinuous cubic phase was related to the diffusion of charge carriers. The microscopic features of charge hopping were modelled using the random walk scheme, and two charge carrier hopping lengths were estimated for two glycolipid systems. For Process I, the hopping length is comparable to the hydrogen bond and is related to the dynamics of the hydrogen bond network. Additionally, that for Process II is comparable to the bilayer spacing, hence confirming that this low-frequency mechanism is associated with the internal dynamics within the phase.
Wettability model for various-sized droplets on solid surfaces
Authors: Yonemoto Yukihiro , Kunugi Tomoaki
Published: August 2014

The wetting phenomenon is crucial for the formation of stable liquid films on solid surfaces. The wettability of a liquid on a solid surface is characterized by the Young equation, which represents an equilibrium condition of a droplet at the three phase contact line. In general, the surface force in the vertical direction on a solid surface is ignored because of the resistance of the solid surface. However, considering the adhesion energy of the droplet rather than the force balance at the contact line, the vertical component of the surface force can be expected to be an important factor during wetting. Based on this concept, an analytical model is developed herein by considering the energy balance including adhesion forces acting not only in the horizontal but also in the vertical direction, in addition to the effect of gravity on the droplet. The validity of the developed model is then evaluated by experimental observation of the wetting phenomena of droplets on low- and high-surface-energy solids. Existing data are also used for evaluation of our model. The developed model describes the wetting phenomena of droplets with sizes ranging from nano- to millimeters under all experimental conditions and exhibits universality. In addition, on the basis of our model, the line tension is discussed. The results indicate that the line tension approach may be considered as a method to explain wetting phenomena by considering gravitational potential and other macroscopic parameters as a single parameter (i.e., line tension).
Evaluation of two-stage system for neutron measurement aiming at increase in count rate at Japan Atomic Energy Agency-Fusion Neutronics Source
Authors: Shinohara K. , Ishii K. , Ochiai K. , Baba M. , Sukegawa A. , Sasao M. , Kitajima S.
Published: August 2014

In order to increase the count rate capability of a neutron detection system as a whole, we propose a multi-stage neutron detection system. Experiments to test the effectiveness of this concept were carried out on Fusion Neutronics Source. Comparing four configurations of alignment, it was found that the influence of an anterior stage on a posterior stage was negligible for the pulse height distribution. The two-stage system using 25 mm thickness scintillator was about 1.65 times the count rate capability of a single detector system for d-D neutrons and was about 1.8 times the count rate capability for d-T neutrons. The results suggested that the concept of a multi-stage detection system will work in practice.
Form fluctuations of polymer loaded spherical microemulsions studied by neutron scattering and dielectric spectroscopy
Authors: Kuttich B. , Falus P. , Grillo I. , Stühn B.
Published: August 2014

We investigate the structure and shell dynamics of the droplet phase in water/AOT/octane microemulsions with polyethyleneglycol (MW = 1500) molecules loaded in the droplets. Size and polydispersity of the droplets is determined with small angle X-ray scattering and small angle neutron scattering experiments. Shell fluctuations are measured with neutron spin echo spectroscopy and related to the dynamic percolation seen in dielectric spectroscopy. Shell fluctuations are found to be well described by the bending modulus of the shell and the viscosities inside and outside the droplets. Addition of the polymer decreases the modulus for small droplets. For large droplets the opposite is found as percolation temperature shifts to higher values.
Wet chemical thinning of molybdenum disulfide down to its monolayer
Authors: Amara Kiran Kumar , Chu Leiqiang , Kumar Rajeev , Toh Minglin , Eda Goki
Published: August 2014

We report on the preparation of mono- and bi-layer molybdenum disulfide (MoS2) from a bulk crystal by facile wet chemical etching. We show that concentrated nitric acid (HNO3) effectively etches thin MoS2 crystals from their edges via formation of MoO3. Interestingly, etching of thin crystals on a substrate leaves behind unreacted mono- and bilayer sheets. The flakes obtained by chemical etching exhibit electronic quality comparable to that of mechanically exfoliated counterparts. Our findings indicate that the self-limiting chemical etching is a promising top-down route to preparing atomically thin crystals from bulk layer compounds.
The role of the space charge region in surface photovoltaic effect
Authors: Toušek J. , Toušková J.
Published: August 2014

The surface photovoltage method is an important tool for semiconductor characterization. Evaluation of photocarrier diffusion length represents one of the most essential applications of this method. The technique is usually limited to samples with thick neutral bulk and thin space charge region (SCR) at the illuminated surface. The purpose of this paper is to remove these restrictions by introducing a more general model. Two different transport processes for the photogenerated carriers are assumed: drift in the SCR and diffusion in the neutral bulk. It was found that the SCR and the bulk contribute to the overall signal independently even in the case of recombination in the depletion region. The presented surface photovoltage technique was successfully applied to samples of different thickness and with differently thick space charge region at the surface. The diffusion length of the minority carrier in inorganic semiconductors as well as the diffusion length of excitons in organic materials were extracted. The thickness of the space charge region is another important parameter obtained by using the model.
Electric field and humidity effects on adsorbed water behavior on BaTiO3 ferroelectric domains studied by scanning probe microscopy
Authors: He D. Y. , Qiao L. J. , Khodayari Mehdi , Volinsky Alex A.
Published: August 2014

Distribution of the adsorbed water on BaTiO3 ferroelectric single crystal (001) surface was investigated by means of scanning probe microscopy. Under high relative humidity, above 95%, the presence of water droplets was observed on domain surfaces. The droplets were up to 20 nm high and their morphology changed when electrical field was applied between the single crystal substrates and droplets via scanning probe microscopy. With an electric field applied parallel to the (001) top surface, the droplets on c domains spread out, followed by complete recovery upon switching the electric field off. However, few droplets on a domains tend to shrink with the electrical field application. It is shown that the screening surface charges and induced charges on droplets surface play a dominant role in droplets behavior.
Reversible piezomagnetoelectric switching in bulk polycrystalline ceramics
Authors: Stevenson T. , Bennett J. , Brown A. P. , Wines T. , Bell A. J. , Smith R. I. , Comyn T. P.
Published: August 2014

Magnetoelectric (ME) coupling in materials offer tremendous advantages in device functionality enabling technologies including advanced electronic memory, combining electronic speed, and efficiency with magnetic robustness. However, low cost polycrystalline ME materials are excluded from most commercial applications, operating only at cryogenic temperatures, impractically large electric/magnetic fields, or with low ME coefficients (1-100 mV/cm Oe). Despite this, the technological potential of single compound ME coupling has continued to drive research into multiferroics over the last two decades. Here we show that by manipulating the large induced atomic strain within the polycrystalline, room temperature multiferroic compound 0.7BiFeO3–0.3PbTiO3, we can induce a reversible, piezoelectric strain controlled ME effect. Employing an in situ neutron diffraction experiment, we have demonstrated that this piezomagnetoelectric effect manifests with an applied electric field >8 kV/mm at the onset of piezoelectric strain, engineered in to the compound by crystallographic phase mixing. This produces a remarkable intrinsic ME coefficient of 1276 mV/cm Oe, due to a strain driven modification to the oxygen sub-lattice, inducing an increase in magnetic moment per Fe3+ ion of +0.142 μB. This work provides a framework for investigations into strain engineered nanostructures to realize low-cost ME devices designed from the atoms up, as well as contributing to the deeper understanding of single phase ME coupling mechanisms.
Peeling-off of the external kink modes at tokamak plasma edge
Authors: Zheng L. J. , Furukawa M.
Published: August 2014

It is pointed out that there is a current jump between the edge plasma inside the last closed flux surface and the scrape-off layer and that the current jump can lead the external kink modes to convert to the tearing modes, due to the current interchange effects [L. J. Zheng and M. Furukawa, Phys. Plasmas 17, 052508 (2010)]. The magnetic reconnection in the presence of tearing modes subsequently causes the tokamak edge plasma to be peeled off to link to the divertors. In particular, the peeling or peeling-ballooning modes can become the “peeling-off” modes in this sense. This phenomenon indicates that the tokamak edge confinement can be worse than the expectation based on the conventional kink mode picture.
Propagation dynamics of laterally colliding plasma plumes in laser-blow-off of thin film
Authors: Kumar Bhupesh , Singh R. K. , Sengupta Sudip , Kaw P. K. , Kumar Ajai
Published: August 2014

We report a systematic investigation of two plume interactions at different spatial separation (3-7 mm) in laser-blow-off. The plasmas plumes are created using Laser-blow-off (LBO) scheme of a thin film. The fast imaging technique is used to record the evolution of seed plasmas and the interaction zone which is formed as a result of interaction of the two seed plasmas. Time resolved optical emission spectroscopy is used to study evolution of optical emissions of the species present in the different regions of the plasmas. Neutral Li emissions (Li I 670.8 nm (2s 2S1/2 ← 2p 2P3/2, 1/2) and Li I 610.3 nm (2p 2P3/2, 1/2 ← 3d 2D3/2, 5/2)) are dominant in the plasmas but significant differences are observed in the emission and estimated plasma parameters of the seed and the interaction zone. The transport of plasma species from the seed plasmas to the interaction zone is discussed in the terms of plume divergence, kinetic energy of particles, and ion acoustic speed. An attempt is made to understand the formation and dynamics of the interaction zone in the colliding LBO seed plasmas.
Dynamic stabilization of the magnetic field surrounding the neutron electric dipole moment spectrometer at the Paul Scherrer Institute
Authors: Afach S. , Bison G. , Bodek K. , Burri F. , Chowdhuri Z. , Daum M. , Fertl M. , Franke B. , Grujic Z. , Hélaine V. , Henneck R. , Kasprzak M. , Kirch K. , Koch H.-C. , Kozela A. , Krempel J. , Lauss B. , Lefort T. , Lemière Y. , Meier M. , Naviliat-Cuncic O. , Piegsa F. M. , Pignol G. , Plonka-Spehr C. , Prashanth P. N. , Quéméner G. , Rebreyend D. , Roccia S. , Schmidt-Wellenburg P. , Schnabel A. , Severijns N. , Voigt J. , Weis A. , Wyszynski G. , Zejma J. , Zenner J. , Zsigmond G.
Published: August 2014

The Surrounding Field Compensation (SFC) system described in this work is installed around the four-layer Mu-metal magnetic shield of the neutron electric dipole moment spectrometer located at the Paul Scherrer Institute. The SFC system reduces the DC component of the external magnetic field by a factor of about 20. Within a control volume of approximately 2.5 m × 2.5 m × 3 m, disturbances of the magnetic field are attenuated by factors of 5–50 at a bandwidth from 10−3 Hz up to 0.5 Hz, which corresponds to integration times longer than several hundreds of seconds and represent the important timescale for the neutron electric dipole moment measurement. These shielding factors apply to random environmental noise from arbitrary sources. This is achieved via a proportional-integral feedback stabilization system that includes a regularized pseudoinverse matrix of proportionality factors which correlates magnetic field changes at all sensor positions to current changes in the SFC coils.
Charge tuning in [111] grown GaAs droplet quantum dots
Authors: Bouet L. , Vidal M. , Mano T. , Ha N. , Kuroda T. , Durnev M. V. , Glazov M. M. , Ivchenko E. L. , Marie X. , Amand T. , Sakoda K. , Wang G. , Urbaszek B.
Published: August 2014

We demonstrate charge tuning in strain free GaAs/AlGaAs quantum dots (QDs) grown by droplet epitaxy on a GaAs(111)A substrate. Application of a bias voltage allows the controlled charging of the QDs from −3|e| to +2|e|. The resulting changes in QD emission energy and exciton fine-structure are recorded in micro-photoluminescence experiments at T = 4 K. We uncover the existence of excited valence and conduction states, in addition to the s-shell-like ground state. We record a second series of emission lines about 25 meV above the charged exciton emission coming from excited charged excitons. For these excited interband transitions, a negative diamagnetic shift of large amplitude is uncovered in longitudinal magnetic fields.
Application of 3A molecular sieve layer in dye-sensitized solar cells
Authors: Yan Yuan , Wang Jinzhong , Yu Qingjiang , Huang Yuewu , Chang Quanhong , Hao Chunlei , Jiao Shujie , Gao Shiyong , Li Hongtao , Wang Dongbo
Published: August 2014

3A molecular sieve layer was used as dehydration and electronic-insulation layer on the TiO2 electrode of dye-sensitized solar cells. This layer diminished the effect of water in electrolyte efficiently and enhanced the performance of cells. The conversion efficiency increased from 9.58% to 10.2%. The good moisture resistance of cells was attributed to the three-dimensional interconnecting structure of 3A molecular sieve with strong adsorption of water molecule. While the performance enhancement benefited from the suppression of the charge recombination of electronic-insulation layer and scattering effect of large particles.
Probing the A1 to L1 transformation in FeCuPt using the first order reversal curve method
Authors: Gilbert Dustin A. , Liao Jung-Wei , Wang Liang-Wei , Lau June W. , Klemmer Timothy J. , Thiele Jan-Ulrich , Lai Chih-Huang , Liu Kai
Published: August 2014

The A1-L10 phase transformation has been investigated in (001) FeCuPt thin films prepared by atomic-scale multilayer sputtering and rapid thermal annealing (RTA). Traditional x-ray diffraction is not always applicable in generating a true order parameter, due to non-ideal crystallinity of the A1 phase. Using the first-order reversal curve (FORC) method, the A1 and L10 phases are deconvoluted into two distinct features in the FORC distribution, whose relative intensities change with the RTA temperature. The L10 ordering takes place via a nucleation-and-growth mode. A magnetization-based phase fraction is extracted, providing a quantitative measure of the L10 phase homogeneity.
Transistor roadmap projection using predictive full-band atomistic modeling
Authors: Salmani-Jelodar M. , Kim S. , Ng K. , Klimeck G.
Published: August 2014

In this letter, a full band atomistic quantum transport tool is used to predict the performance of double gate metal-oxide-semiconductor field-effect transistors (MOSFETs) over the next 15 years for International Technology Roadmap for Semiconductors (ITRS). As MOSFET channel lengths scale below 20 nm, the number of atoms in the device cross-sections becomes finite. At this scale, quantum mechanical effects play an important role in determining the device characteristics. These quantum effects can be captured with the quantum transport tool. Critical results show the ON-current degradation as a result of geometry scaling, which is in contrast to previous ITRS compact model calculations. Geometric scaling has significant effects on the ON-current by increasing source-to-drain (S/D) tunneling and altering the electronic band structure. By shortening the device gate length from 20 nm to 5.1 nm, the ratio of S/D tunneling current to the overall subthreshold OFF-current increases from 18% to 98%. Despite this ON-current degradation by scaling, the intrinsic device speed is projected to increase at a rate of at least 8% per year as a result of the reduction of the quantum capacitance.
A portable lab-on-a-chip system for gold-nanoparticle-based colorimetric detection of metal ions in water
Authors: Zhao Chen , Zhong Guowei , Kim Da-Eun , Liu Jinxia , Liu Xinyu
Published: August 2014

Heavy metal ions released into various water systems have a severe impact on the environment and human beings, and excess exposure to toxic metal ions through drinking water poses high risks to human health and causes life-threatening diseases. Thus, there is high demand for the development of a rapid, low-cost, and sensitive method for detection of metal ions in water. We present a portable analytical system for colorimetric detection of lead (Pb2+) and aluminum (Al3+) ions in water based on gold nanoparticle probes and lab-on-a-chip instrumentation. The colorimetric detection of metal ions is conducted via single-step assays with low limits of detection (LODs) and high selectivity. We design a custom-made microwell plate and a handheld colorimetric reader for implementing the assays and quantifying the signal readout. The calibration experiments demonstrate that this portable system provides LODs of 30 ppb for Pb2+ and 89 ppb for Al3+, both comparable to bench-top analytical spectrometers. It promises an effective platform for metal ion analysis in a more economical and convenient way, which is particularly useful for water quality monitoring in field and resource-poor settings.
Lateral-deflection-controlled friction force microscopy
Authors: Fukuzawa Kenji , Hamaoka Satoshi , Shikida Mitsuhiro , Itoh Shintaro , Zhang Hedong
Published: August 2014

Lateral-deflection-controlled dual-axis friction force microscopy (FFM) is presented. In this method, an electrostatic force generated with a probe-incorporated micro-actuator compensates for friction force in real time during probe scanning using feedback control. This equivalently large rigidity can eliminate apparent boundary width and lateral snap-in, which are caused by lateral probe deflection. The method can evolve FFM as a method for quantifying local frictional properties on the micro/nanometer-scale by overcoming essential problems to dual-axis FFM.
Ultraviolet GaN photodetectors on Si via oxide buffer heterostructures with integrated short period oxide-based distributed Bragg reflectors and leakage suppressing metal-oxide-semiconductor contacts
Authors: Szyszka A. , Lupina L. , Lupina G. , Schubert M. A. , Zaumseil P. , Haeberlen M. , Storck P. , Thapa S. B. , Schroeder T.
Published: August 2014

Based on a novel double step oxide buffer heterostructure approach for GaN integration on Si, we present an optimized Metal-Semiconductor-Metal (MSM)-based Ultraviolet (UV) GaN photodetector system with integrated short-period (oxide/Si) Distributed Bragg Reflector (DBR) and leakage suppressing Metal-Oxide-Semiconductor (MOS) electrode contacts. In terms of structural properties, it is demonstrated by in-situ reflection high energy electron diffraction and transmission electron microscopy-energy dispersive x-ray studies that the DBR heterostructure layers grow with high thickness homogeneity and sharp interface structures sufficient for UV applications; only minor Si diffusion into the Y2O3 films is detected under the applied thermal growth budget. As revealed by comparative high resolution x-ray diffraction studies on GaN/oxide buffer/Si systems with and without DBR systems, the final GaN layer structure quality is not significantly influenced by the growth of the integrated DBR heterostructure. In terms of optoelectronic properties, it is demonstrated that—with respect to the basic GaN/oxide/Si system without DBR—the insertion of (a) the DBR heterostructures and (b) dark current suppressing MOS contacts enhances the photoresponsivity below the GaN band-gap related UV cut-off energy by almost up to two orders of magnitude. Given the in-situ oxide passivation capability of grown GaN surfaces and the one order of magnitude lower number of superlattice layers in case of higher refractive index contrast (oxide/Si) systems with respect to classical III-N DBR superlattices, virtual GaN substrates on Si via functional oxide buffer systems are thus a promising robust approach for future GaN-based UV detector technologies.
Wafer-size free-standing single-crystalline graphene device arrays
Authors: Li Peng , Jing Gaoshan , Zhang Bo , Sando Shota , Cui Tianhong
Published: August 2014

We report an approach of wafer-scale addressable single-crystalline graphene (SCG) arrays growth by using pre-patterned seeds to control the nucleation. The growth mechanism and superb properties of SCG were studied. Large array of free-standing SCG devices were realized. Characterization of SCG as nano switches shows excellent performance with life time (>22 000 times) two orders longer than that of other graphene nano switches reported so far. This work not only shows the possibility of producing wafer-scale high quality SCG device arrays but also explores the superb performance of SCG as nano devices.
Tunable electrochemical pH modulation in a microchannel monitored via the proton-coupled electro-oxidation of hydroquinone
Authors: Contento Nicholas M. , Bohn Paul W.
Published: August 2014

Electrochemistry is a promising tool for microfluidic systems because it is relatively inexpensive, structures are simple to fabricate, and it is straight-forward to interface electronically. While most widely used in microfluidics for chemical detection or as the transduction mechanism for molecular probes, electrochemical methods can also be used to efficiently alter the chemical composition of small (typically <100 nl) microfluidic volumes in a manner that improves or enables subsequent measurements and sample processing steps. Here, solvent (H2O) electrolysis is performed quantitatively at a microchannel Pt band electrode to increase microchannel pH. The change in microchannel pH is simultaneously tracked at a downstream electrode by monitoring changes in the i-V characteristics of the proton-coupled electro-oxidation of hydroquinone, thus providing real-time measurement of the protonated forms of hydroquinone from which the pH can be determined in a straightforward manner. Relative peak heights for protonated and deprotonated hydroquinone forms are in good agreement with expected pH changes by measured electrolysis rates, demonstrating that solvent electrolysis can be used to provide tunable, quantitative pH control within a microchannel.
Gallium loading of gold seed for high yield of patterned GaAs nanowires
Authors: Boulanger J. P. , Chia A. C. E. , LaPierre R. R.
Published: August 2014

A method is presented for maximizing the yield and crystal phase purity of vertically aligned Au-assisted GaAs nanowires grown with an SiOx selective area epitaxy mask on GaAs (111)B substrates. The nanowires were grown by the vapor-liquid-solid (VLS) method in a gas source molecular beam epitaxy system. During annealing, Au VLS seeds will alloy with the underlying GaAs substrate and collect beneath the SiOx mask layer. This behavior is detrimental to obtaining vertically aligned, epitaxial nanowire growth. To circumvent this issue, Au droplets were pre-filled with Ga assuring vertical yields in excess of 99%.
Crossover of conduction mechanism in Sr2IrO4 epitaxial thin films
Authors: Lu Chengliang , Quindeau Andy , Deniz Hakan , Preziosi Daniele , Hesse Dietrich , Alexe Marin
Published: August 2014

High quality epitaxial Sr2IrO4 thin films with various thicknesses (9–300 nm) have been grown on SrTiO3 (001) substrates and their electric transport properties have been investigated. All samples showed the expected insulating behavior with a strong resistivity dependence on film thickness, which can be as large as three orders of magnitude at low temperature. A close examination of the transport data revealed interesting crossover behaviors for the conduction mechanism upon variation of thickness and temperature. While Mott variable range hopping (VRH) dominated the transport for films thinner than 85 nm, high temperature (>200 K) thermal activation behavior was observed for films with large thickness (≥85 nm), which was followed by a crossover from Mott to Efros-Shklovskii (ES) VRH in the low temperature range. This low temperature crossover from Mott to ES VRH indicates the presence of a Coulomb gap (∼3 meV). Our results demonstrate the competing and tunable conduction in Sr2IrO4 thin films, which in turn would be helpful for understanding the insulating nature related to strong spin-orbital-coupling of the 5d iridates.
Modelling pasture management and livestock genotype interventions to improve whole-farm productivity and reduce greenhouse gas emissions intensities
Authors: Harrison Matthew T. , Christie Karen M. , Rawnsley Richard P. , Eckard Richard J.
Published: August 2014

Livestock greenhouse gas (GHG) emissions form the largest proportion of emissions from agriculture. Here we seek intervention strategies for sustainably intensifying the productivity of prime lamb enterprises without increasing net farm emissions. We apply a biophysical model and an emissions calculator to determine the implications of several interventions to a prime lamb farm in south-eastern Australia. We examine the effects of lamb liveweight or age at sale, weaning rate, maiden ewe joining age, genetic feed-use efficiency, supplementary grain feeding according to green pasture availability, soil fertility and botanical composition. For each intervention, stocking rates were optimised to the lesser of a minimum ground cover threshold or a maximum supplementary grain feeding threshold. Total animal production of the baseline farm was 478 kg clean fleece weight plus liveweight (CFW+LWT)/ha.annum and ranged from 166 to 609 kg CFW+LWT/ha.annum for interventions that replaced existing pastures with annual ryegrass or increased soil fertility respectively. Annual GHG emissions intensity of the baseline farm was 8.7 kg CO2-e/kg CFW+LWT and varied between 7.7 and 9.2 kg CO2-e/kg CFW+LWT for interventions that reduced maiden ewe joining age or increased sale liveweight, respectively. Stocking rate primarily governed total animal production, and in many cases production drove emissions, so interventions that increased production did not always reduce emissions intensity. Indeed, replacing existing perennial ryegrass/subterranean clover mixed pastures with perennial legume swards caused large reductions in both production and emissions, and interventions that increased soil fertility via phosphate addition caused large increases in production and emissions; as a consequence, both strategies had little effect on emissions intensity. Implementing several beneficial interventions simultaneously further increased production and reduced emissions intensity relative to implementing individual interventions alone. Baseline production increased by 61% by increasing soil fertility, improving feed-use efficiency and reducing the joining age of maiden ewes, while baseline emissions intensity was reduced by 17% by improving feed use efficiency, reducing the joining age of maiden ewes and supplementary grain feeding. We demonstrate that imposing several strategies on existing sheep farming systems simultaneously is more conducive to sustainable agricultural intensification than is imposing any single intervention alone, provided individual strategies were beneficial in their own right. The best strategies for both sustainably increasing production and reducing emissions intensity are those that decouple the linkage between production and emissions such as interventions that shift the balance of the flock away from adults and towards juveniles while holding average annual stocking rates constant.
Development of a dynamic, mechanistic model of nutritional and reproductive processes in dairy cattle
Authors: Huber K. , Kenez A. , McNamara J. P. , Shields S. L.
Published: August 2014

Our knowledge of genetics, nutrient metabolism and reproductive physiology demands an integrated systems approach to both research and on-farm application. Existing mechanistic, dynamic and biochemical models exist which describe (1) nutrient metabolism and control of nutritional processes and (2) estrous cyclicity in lactating dairy cows. The metabolic model contains a simple aggregated model of lipogenesis, esterification and lipolysis; however, it is not sufficiently detailed to provide a research framework for future research. The estrous model describes the cyclicity of follicular development as well as several key reproductive hormones, but it does not contain any nutritional control as we understand it. Therefore, we developed a more detailed model of metabolism in adipose tissue, including uptake of glucose and fatty acids, fatty acid activation to the AcylCoA form, lipogenesis from acetate and butyrate, esterification of glycerol and fatty acids, and lipolysis and release of fatty acids and glycerol. The estrous model was expanded to include control of follicular growth by IGFI (~1 mm increase in diameter for a 20 ng/mL difference in IGFI; and degradation of estrogen and progesterone (~1.6 % increase in degradation per kg DM intake equivalent). Changes in follicular growth due to IGFI and increase in steroid degradation due to increased metabolic rate (as happens during lactation) demonstrate subtle and unpredictable changes in hormonal cyclicity, similar in fact to the complex effects of anabolic and catabolic signals in the cow. The model demonstrates behaviour and sensitivity to nutrient uptake and metabolic rate consistent with known biological processes. This model may be used to help interpret genomic and transcriptomic data, to pinpoint the most effective ways to select and manage for changes in productive and reproductive efficiency.
Cytochemical investigation at different microsporogenesis phases of male sterility in wheat, as induced by the chemical hybridising agent SQ-1
Authors: Song Yulong , Wang Junwei , Zhang Pengfei , Zhang Gaisheng , Zhang Longyu , Zhao Xinliang , Niu Na , Ma Shoucai
Published: August 2014

This study used semi-thin sectioning and cytochemistry to investigate the relationship between pollen nutrient metabolism and pollen abortion in male sterile lines of wheat induced by SQ-1 (a chemical hybridising agent). Anthers were collected from the tetrad to trinucleate stages, and 4ʹ,6-diamidino-2-phenylindole staining was used to visualise nuclei and confirm the development stage. Sudan Black B, periodic acid–Schiff, Coomassie Brilliant Blue, and toluidine blue were used to detect lipids, starch, proteins, and acidic polyanions, respectively. Semi-thin sectioning indicated that nutrient accumulation was much higher in the fertile line 1376 than in the sterile line 1376-PHYMS. Further, no lipids were found in the free microspore stage in the sterile line; however, at the late microspore stage, more proteins and acidic polyanions were found in the sterile line 1376-PHYMS pollen than in the fertile line 1376 pollen. From the binucleate to trinucleate pollen stages, the starch content was low and the intine considerably thinner in the pollen of the 1376-PHYMS line. SQ-1 probably hampered nutrient metabolism in the anthers, leading to decreased nutrient supply and abnormal intine formation, ultimately resulting in pollen abortion. A new mechanism for nutrient absorption, i.e. endocytosis of Ubisch bodies or orbicules by the intine through the germinal aperture, was revealed.
Effects of amendment of different biochars on soil enzyme activities related to carbon mineralisation
Authors: Ouyang Lei , Tang Qian , Yu Liuqian , Zhang Renduo
Published: August 2014

This study aimed to investigate the effects of different biochars on soil enzyme activities associated with soil carbon (C) mineralisation. Biochars were produced from two types of feedstock (fresh dairy manure and pine tree woodchip) at temperatures of 300°C, 500°C, and 700°C. Each biochar was mixed at a ratio of 5% (w/w) with a forest loamy soil and the mixture was incubated at 25°C for 180 days. Soil mineralisation rates, soil dissolved organic C, soil microbial biomass C, and five soil enzyme activities were measured during different incubation periods. Results showed that biochar addition increased soil enzyme activities at the early stage (mainly within the first 80 days) because biochar brought available nutrients to the soil and increased soil dissolved organic C and microbial activity. Soil enzyme activities were enhanced more by the dairy manure biochars than by the woodchip biochars (P < 0.05). The enhancement effect on enzyme activities (except catalase activity) was greater in the treatments with biochars produced at lower pyrolysis temperature (300°C). Linear relationships between some soil enzymes and C-mineralisation rates might indicate that the increased enzyme activities stimulated soil C mineralisation at the early stage. However, the biochar additions could result in great C sequestration in the long term, especially for the woodchip biochars pyrolysed at higher temperatures.
Nanoscale structure of the BMP antagonist chordin supports cooperative BMP binding
Authors: Troilo Helen , Zuk Alexandra V. , Tunnicliffe Richard B. , Wohl Alexander P. , Berry Richard , Collins Richard F. , Jowitt Thomas A. , Sengle Gerhard , Baldock Clair
Published: August 2014

Significance

Bone morphogenetic proteins (BMPs) are essential signaling molecules important in embryo development and maintaining tissue function in adulthood. BMPs are regulated outside the cell by inhibitors such as chordin. The structure of chordin is unknown as extracellular proteins are generally not suitable for high-resolution methods. This study uses electron microscopy and other techniques to determine the shape of human chordin. It has a compact horseshoe-shaped structure with the terminal BMP-binding regions protruding as prongs. The spacing of these domains supports a cooperative binding arrangement with BMPs. We compared BMP binding and inhibition by chordin with two truncated chordin variants. Proteolytic cleavage has little effect on binding of BMP-4 and BMP-7 but C-terminal cleavage makes chordin a better BMP inhibitor.
Translocalized IgA mediates neutralization and stimulates innate immunity inside infected cells
Authors: Bidgood Susanna R. , Tam Jerry C. H. , McEwan William A. , Mallery Donna L. , James Leo C.
Published: August 2014

Significance

In recent years, the important immune protective role of IgA, the most plentiful antibody type, has become increasingly clear. In this study, we show that IgA is carried inside cells during infection by a nonenveloped virus, adenovirus, which commonly causes respiratory disease. Once inside the cell, IgA is recognized by the newly identified cytosolic antibody receptor, tripartite motif-containing protein 21 (TRIM21), leading to destruction of virus by the proteasome and immune activation. We show that TRIM21 interacts directly with IgA to initiate these responses and explain how binding is accomplished. Our work identifies TRIM21 as the only antibody receptor to bind the three most prevalent circulatory antibodies, IgG, IgM, and IgA, and enlarges the role of IgA in immune protection.
The identity issue in bi- and multilingual repertoires in South Africa
Authors: Coetzee-Van Rooy Susan
Published: August 2014

Identity construction drives the development of postcolonial Englishes in Schneider’s Dynamic Model. Contexts like those of South Africa where widespread bi- and multilingualism are observed challenge notions of English as sole “identity carrier” postulated in the model. Findings from a questionnaire and interview study reported in this article indicate that: (a) urban participants are bi- and multilingual, (b) the home language is the carrier of ethnic or cultural identity, (c) English is part of the repertoires of the participants, (d) “being multilingual” is the linguistic marker of a South African identity. The refinement of the identity construction in this very useful model indicates that South Africa will probably not progress conclusively past Stage 3 in the Dynamic Model in the near future.
Stylistic and sociolinguistic variation in Schneider’s Nativization Phase
Authors: Huber Magnus
Published: August 2014

Taking educated Ghanaian English (GhE) as an example, this article considers the place of stylistic and sociolinguistic variation in Schneider’s (2003, 2007) Dynamic Model of the evolution of New Englishes. The study examines variation in one phonological and one morphosyntactic variable, investigating t-affrication with regard to variation across the two genders and two speech styles in spoken GhE, and analysing relativizer choice in written texts of differing formality. The results demonstrate that GhE shows robust and consistent stylistic and gender-related variation, although it has only reached Phase 3 of Schneider’s Dynamic Model. This is noteworthy on a theoretical level since the emergence of local sociolinguistic norms would not have been expected until Phase 5.
Differentiation in Australian English
Authors: Peters Pam
Published: August 2014

The Differentiation Phase (Phase 5 of Schneider’s Dynamic Model) has so far been reached by only a handful of settler Englishes: American English, Australian English, Canadian English, New Zealand English, with internal diversification as well as unique admixtures of indigenized and adstrate varieties. In Australian English this is in its early stages, though there’s little adstrate differentiation in evidence despite continuing waves of immigration. Fully fledged differentiation (including phonological, morphosyntactic and lexical divergences) is however conspicuous in Australian Aboriginal communities, in a distinctive indigenized English (Aboriginal English) which is spoken in widely separated areas especially across the centre and north of Australia. The resilience of AborE poses larger questions of how an indigenized variety can continue to evolve under an established and dominant settler variety.
The cognitive evolution of Englishes
Authors: Hoffmann Thomas
Published: August 2014

Schneider’s Dynamic Model (2007) predicts that it is the lexicon-syntax interface that exhibits first traces of the emergence of characteristic structural innovations during the phase of Nativization. In this paper, I will show how a Construction Grammar approach provides a cognitive explanation for this phenomenon. I will then illustrate the advantages of a Construction Grammar analysis by focussing on Comparative Correlative (CC) constructions (e.g. The higher the price is, the more interesting the product is.; cf. Fillmore et al. 1988; Sag 2010). As the statistical analysis of data from various corpora from the International Corpus of English project show, all varieties exhibit similar processing effects, but differ greatly with respect to their reliance on partly substantive, partly schematic meso-constructions.
English in Cyprus and Namibia
Authors: Buschfeld Sarah
Published: August 2014

This paper follows up on the recent claim that the strict separation between second-language varieties of English and learner Englishes is inadequate. It approaches this idea by combining theoretical considerations on the traditionally established differences between the two types of English with findings from case studies on English in Cyprus (cf. Buschfeld 2013) and English in Namibia (cf. Buschfeld & Kautzsch fc. 2014). The results suggest that both Englishes defy clear classification as either learner language or second-language variety and therefore show that the strict separation of these two types of English should be reconsidered. Finally, the paper discusses a range of theoretical implications these findings bring about and if / how Schneider’s (2007) Dynamic Model can account for such cases.
Innovation in pre-World War II AAVE?
Authors: Miethaner Ulrich
Published: August 2014

This article tests the “divergence hypothesis”, which holds that in the 20th century African American Vernacular English (AAVE) underwent significant structural changes and consequently diverged from white varieties. To this end five “innovative” features of AAVE are scrutinized in BLUR, an electronic corpus of blues lyrics recorded in the first half of the 20th century: habitual be + V-ing, resultative be done, semi-auxiliary come, intensifying steady and counterfactual call oneself. Evidence from BLUR suggests that these features already were part of AAVE grammar in the (late) 19th century. Thus they started to be restructured earlier than the divergence hypothesis suggests. A close look at the semantics of these features also reveals two core meanings: “habituality” (be) and “emotional intensity” (V-ing).
Yesterday’s founder population, today’s Englishes
Authors: Lim Lisa
Published: August 2014

This paper highlights a less well known player in the contact dynamics involved in the evolution of Singapore English (SgE): the Peranakans – descendants of 18th / 19th-century southern Chinese traders in Malaya and local women, who became a prestigious minority group. As multilingual, early English adopters, and dominant in the ecology, the Peranakans demonstrate the significance of a founder population, in how their features – here, their original vernacular Baba Malay via Peranakan English – are persistent and influential in the evolution of contact varieties in a multilingual ecology. This paper also considers the current positioning of the Peranakans in their 21st-century revival in the changed sociolinguistic context of Singapore and what this means for the current and future evolution of SgE.
The language of butchery, the UK’s last public craft
Authors: Upton Clive
Published: August 2014

Drawing on survey material from the 1970s, supplemented by present-day observations, this chapter sets out some core matters of the language used by butchers, and goes on to elaborate on three disparate matters of general linguistic concern. It takes a language-historical issue concerning English and French etymologies beyond the basic level at which it is customarily considered. It highlights lexicographic shortcomings as regards the treatment of semi-technical vocabulary. And it explains in some detail a little-known variety of slang, especially connected to butchers but not solely their preserve. The linguistic space inhabited by butchers emerges as both particular to them and relevant on a wider stage.
How Inefficient Are Nutrient Application Limits? A Dynamic Analysis of Groundwater Nitrate Pollution from Concentrated Animal Feeding Operations
Authors: Wang Jingjing , Baerenklau Kenneth A.
Published: August 2014

Animal waste from concentrated animal feeding operations (CAFOs) is a significant contributor to nitrate contamination of groundwater. To evaluate the cost‐effectiveness of alternative policies for controlling nitrate pollution at both the field and farm level, this article utilizes a structural dynamic model of a representative CAFO. The model accounts for herd management, manure handling systems, crop rotations, water sources, irrigation systems, waste disposal options, and pollutant emissions. Results show that the standard approach of limiting the amount of animal waste that may be applied to fields reduces net farm income by more than 25%, whereas the most cost‐effective emission‐based policies reduce income only marginally. This motivates greater consideration for nonpoint source pollution control policies that target estimated emissions. Furthermore, price instruments are shown to slightly outperform quantity instruments under conditions that are typical for CAFOs. The results also show that adopting alternative technologies and practices is crucial for cost‐effective abatement, and demonstrate the importance of accounting for the spatial heterogeneity of both irrigation water and salinity when designing policy mechanisms for nitrate pollution control.