bluuebunny/crossref_metadata_2025 huggingface dataset:
A porous cobalt-based MOF with high CO2 selectivity and uptake capacity
Authors: Du Liting , Lu Zhiyong , Ma Mengtao , Su Fan , Xu Li
Published: March 2015

A porous cobalt-based metal–organic framework [CoL2−]n has been designed by self-assembling [Co2(COO)4] paddlewheel SBUs and a novel trigonal hetero–functional ligand. [CoL2−]n exhibits large CO2 uptake and selectivity.
Stability of molecular layer deposited zincone films: experimental and theoretical exploration
Authors: Choudhury Devika , Rajaraman Gopalan , Sarkar Shaibal K.
Published: March 2015

Experimental and theoretical degradation study of MLD grown hybrid inorganic–organic zincone films.
A biocompatible process to prepare hyaluronan-based material able to self-assemble into stable nano-particles
Authors: Calce Enrica , Ringhieri Paola , Mercurio Flavia Anna , Leone Marilisa , Bugatti Valeria , Saviano Michele , Vittoria Vittoria , De Luca Stefania
Published: March 2015

A microwave-assisted solvent-free process was employed to esterify palmitic, oleic and linoleic acids by hyaluronan alcoholic functions. The obtained HA derivatives were able to form stable spherical nano-sized aggregates, in a range of 63–266 nm.
Photo-assisted inkjet printing of antibodies onto cellulose for the eco2-friendly preparation of immunoassay membranes
Authors: Credou Julie , Faddoul Rita , Berthelot Thomas
Published: March 2015

Immunoassay membranes were produced by inkjet printing and photolinker-free photoimmobilization of antibodies onto cellulose.
Investigation of DNA binding abilities of solid lipid nanoparticles based on p-tert-butylthiacalix[4]arene platform
Authors: Galukhin Andrey , Erokhin Anton , Imatdinov Ilnaz , Osin Yuri
Published: March 2015

Amphiphilic thiacalix[4]arene functionalized with guanidinium groups forms stable solid lipid nanoparticles (SLNs) with high binding affinity to double-stranded DNA.
Low temperature magnetic and transport properties of LSMO–PZT nanocomposites
Authors: Dwivedi Gopeshwar Dhar , Kumar Manish , Shahi Prashant , Barman Anjan , Chatterjee Sandip , Ghosh Anup K.
Published: March 2015

(a)M–Hcurves of different nanocomposites (NCs) at 80 K. Left and right insets showM vs.Hand dM/dH vs.Hcurves respectively; (b) Magneto-resistance (MR)vs.Hcurve of different NCs at 200 K. Inset figure shows MRvs.Hcurve for a typical NC at various temperatures.
Cr(i)Cl as well as Cr+are stabilised between two cyclic alkyl amino carbenes
Authors: Samuel Prinson P. , Neufeld Roman , Chandra Mondal Kartik , Roesky Herbert W. , Herbst-Irmer Regine , Stalke Dietmar , Demeshko Serhiy , Meyer Franc , Rojisha Vallyanga Chalil , De Susmita , Parameswaran Pattiyil , Stückl A. Claudia , Kaim Wolfgang , Christian Jonathan H. , Bindra Jasleen K. , Dalal Naresh S.
Published: March 2015

Complexes with two and three coordinate chromium(i).
Porous activated graphene nanoplatelets incorporated in TiO2photoanodes for high-efficiency dye-sensitized solar cells
Authors: Ma Huanmei , Tian Jianhua , Cui Lan , Liu Yuanyuan , Bai Shuming , Chen Hang , Shan Zhongqiang
Published: March 2015

We report the facile synthesis of activated graphene nanoplatelets with a porous structure as a transport pathway for ions in the electrolyte and electron transfer medium in DSSCs.
Decorating graphene oxide/nanogold with dextran-based polymer brushes for the construction of ultrasensitive electrochemical enzyme biosensors
Authors: Boujakhrout Abderrahmane , Sánchez Alfredo , Díez Paula , Jiménez-Falcao Sandra , Martínez-Ruiz Paloma , Peña-Álvarez Miriam , Pingarrón José M. , Villalonga Reynaldo
Published: March 2015

A novel strategy to prepare a water-soluble graphene derivative by attaching dextran polymer brushes.
White light emitting single polymer from aggregation enhanced emission: a strategy through supramolecular assembly
Authors: Ravindran Ezhakudiyan , Ananthakrishnan Soundaram Jeevarathinam , Varathan Elumalai , Subramanian Venkatesan , Somanathan Narayanasastri
Published: March 2015

Aggregation induced emission enhancement (AIEE) is widely regarded as an efficient tool to offset the problem of aggregation caused quenching (ACQ) in luminogens.
RECQ1 interacts with FEN-1 and promotes binding of FEN-1 to telomeric chromatin
Authors: Sami Furqan , Lu Xing , Parvathaneni Swetha , Roy Rabindra , Gary Ronald K. , Sharma Sudha
Published: March 2015

RecQ helicases are a family of highly conserved proteins that maintain genomic stability through their important roles in replication restart mechanisms. Cellular phenotypes of RECQ1 deficiency are indicative of aberrant repair of stalled replication forks, but the molecular functions of RECQ1, the most abundant of the five known human RecQ homologues, have remained poorly understood. We show that RECQ1 associates with FEN-1 (flap endonuclease-1) in nuclear extracts and exhibits direct protein interaction in vitro. Recombinant RECQ1 significantly stimulated FEN-1 endonucleolytic cleavage of 5′-flap DNA substrates containing non-telomeric or telomeric repeat sequence. RECQ1 and FEN-1 were constitutively present at telomeres and their binding to the telomeric chromatin was enhanced following DNA damage. Telomere residence of FEN-1 was dependent on RECQ1 since depletion of RECQ1 reduced FEN-1 binding to telomeres in unperturbed cycling cells. Our results confirm a conserved collaboration of human RecQ helicases with FEN-1 and suggest both overlapping and specialized roles of RECQ1 in the processing of DNA structure intermediates proposed to arise during replication, repair and recombination.
Processing of protein ADP-ribosylation by Nudix hydrolases
Authors: Palazzo Luca , Thomas Benjamin , Jemth Ann-Sofie , Colby Thomas , Leidecker Orsolya , Feijs Karla L.H. , Zaja Roko , Loseva Olga , Puigvert Jordi Carreras , Matic Ivan , Helleday Thomas , Ahel Ivan
Published: March 2015

ADP-ribosylation is a post-translational modification (PTM) of proteins found in organisms from all kingdoms of life which regulates many important biological functions including DNA repair, chromatin structure, unfolded protein response and apoptosis. Several cellular enzymes, such as macrodomain containing proteins PARG [poly(ADP-ribose) glycohydrolase] and TARG1 [terminal ADP-ribose (ADPr) protein glycohydrolase], reverse protein ADP-ribosylation. In the present study, we show that human Nudix (nucleoside diphosphate-linked moiety X)-type motif 16 (hNUDT16) represents a new enzyme class that can process protein ADP-ribosylation in vitro, converting it into ribose-5′-phosphate (R5P) tags covalently attached to the modified proteins. Furthermore, our data show that hNUDT16 enzymatic activity can be used to trim ADP-ribosylation on proteins in order to facilitate analysis of ADP-ribosylation sites on proteins by MS.
PEDF and its roles in physiological and pathological conditions: implication in diabetic and hypoxia-induced angiogenic diseases
Authors: He Xuemin , Cheng Rui , Benyajati Siribhinya , Ma Jian-xing
Published: March 2015

Pigment epithelium-derived factor (PEDF) is a broadly expressed multifunctional member of the serine proteinase inhibitor (serpin) family. This widely studied protein plays critical roles in many physiological and pathophysiological processes, including neuroprotection, angiogenesis, fibrogenesis and inflammation. The present review summarizes the temporal and spatial distribution patterns of PEDF in a variety of developing and adult organs, and discusses its functions in maintaining physiological homoeostasis. The major focus of the present review is to discuss the implication of PEDF in diabetic and hypoxia-induced angiogenesis, and the pathways mediating PEDF's effects under these conditions. Furthermore, the regulatory mechanisms of PEDF expression, function and degradation are also reviewed. Finally, the therapeutic potential of PEDF as an anti-angiogenic drug is briefly summarized.
Order and correlation contributions to the entropy of hydrophobic solvation
Authors: Liu Maoyuan , Besford Quinn Alexander , Mulvaney Thomas , Gray-Weale Angus
Published: March 2015

The entropy of hydrophobic solvation has been explained as the result of ordered solvation structures, of hydrogen bonds, of the small size of the water molecule, of dispersion forces, and of solvent density fluctuations. We report a new approach to the calculation of the entropy of hydrophobic solvation, along with tests of and comparisons to several other methods. The methods are assessed in the light of the available thermodynamic and spectroscopic information on the effects of temperature on hydrophobic solvation. Five model hydrophobes in SPC/E water give benchmark solvation entropies via Widom’s test-particle insertion method, and other methods and models are tested against these particle-insertion results. Entropies associated with distributions of tetrahedral order, of electric field, and of solvent dipole orientations are examined. We find these contributions are small compared to the benchmark particle-insertion entropy. Competitive with or better than other theories in accuracy, but with no free parameters, is the new estimate of the entropy contributed by correlations between dipole moments. Dipole correlations account for most of the hydrophobic solvation entropy for all models studied and capture the distinctive temperature dependence seen in thermodynamic and spectroscopic experiments. Entropies based on pair and many-body correlations in number density approach the correct magnitudes but fail to describe temperature and size dependences, respectively. Hydrogen-bond definitions and free energies that best reproduce entropies from simulations are reported, but it is difficult to choose one hydrogen bond model that fits a variety of experiments. The use of information theory, scaled-particle theory, and related methods is discussed briefly. Our results provide a test of the Frank-Evans hypothesis that the negative solvation entropy is due to structured water near the solute, complement the spectroscopic detection of that solvation structure by identifying the structural feature responsible for the entropy change, and point to a possible explanation for the observed dependence on length scale. Our key results are that the hydrophobic effect, i.e. the signature, temperature-dependent, solvation entropy of nonpolar molecules in water, is largely due to a dispersion force arising from correlations between rotating permanent dipole moments, that the strength of this force depends on the Kirkwood g-factor, and that the strength of this force may be obtained exactly without simulation.
Scaling of geochemical reaction rates via advective solute transport
Authors: Hunt A. G. , Ghanbarian B. , Skinner T. E. , Ewing R. P.
Published: March 2015

Transport in porous media is quite complex, and still yields occasional surprises. In geological porous media, the rate at which chemical reactions (e.g., weathering and dissolution) occur is found to diminish by orders of magnitude with increasing time or distance. The temporal rates of laboratory experiments and field observations differ, and extrapolating from laboratory experiments (in months) to field rates (in millions of years) can lead to order-of-magnitude errors. The reactions are transport-limited, but characterizing them using standard solute transport expressions can yield results in agreement with experiment only if spurious assumptions and parameters are introduced. We previously developed a theory of non-reactive solute transport based on applying critical path analysis to the cluster statistics of percolation. The fractal structure of the clusters can be used to generate solute distributions in both time and space. Solute velocities calculated from the temporal evolution of that distribution have the same time dependence as reaction-rate scaling in a wide range of field studies and laboratory experiments, covering some 10 decades in time. The present theory thus both explains a wide range of experiments, and also predicts changes in the scaling behavior in individual systems with increasing time and/or length scales. No other theory captures these variations in scaling by invoking a single physical mechanism. Because the successfully predicted chemical reactions include known results for silicate weathering rates, our theory provides a framework for understanding changes in the global carbon cycle, including its effects on extinctions, climate change, soil production, and denudation rates. It further provides a basis for understanding the fundamental time scales of hydrology and shallow geochemistry, as well as the basis of industrial agriculture.
On the detection of mesospheric meteoric smoke particles embedded in noctilucent cloud particles with rocket-borne dust probes
Authors: Antonsen T. , Havnes O.
Published: March 2015

Mesospheric nanoparticles in the forms of water ice particles and meteoric smoke particles (MSPs) exist in the middle atmosphere where they often play a decisive role in cloud formation and in chemical processes. Direct in situ observations of mesospheric nanoparticles have been made possible by rocket probes developed during the last two decades. Although progress has been made in mapping properties such as electric charge, sizes, and interaction with the plasma and neutral gas, more observations are needed on the size distribution, chemical content, and structure of the MSP to determine their role in cloud formation and chemistry in the mesosphere and stratosphere. We here present the result of a detailed analysis of the performance of a new dust probe MUltiple Dust Detector (MUDD) [O. Havnes et al., J. Atmos Soll.-Terr. Phys. 118, 190 (2014); O. Havenes et al., ibid. (in press)], which should give information of the size distribution of MSP by fragmenting impacting ice particles and releasing a fraction of the MSP which most probably are embedded in them [O. Havnes and L. I. Naesheim, Ann. Geophys. 25, 623 (2007); M. E. Hervig et al., J. Atmos. Sol.-Terr. Phys. 84-85, 1 (2012)]. We first determine the electric field structure and neutral gas condition in the interior of the probe and from this compute, the dynamics and current contribution of the charged fragments to the currents measured as the probe scans the fragment energy. For the single MUDD probe flown in July 2011 on the PHOCUS payload, we find that the fragment currents at the three retarding potentials for MUDD of 0, 10, and 20 V correspond to fragment sizes of ≳0.6 nm, >1.5 nm, and >1.8 nm if the fragments have a negative unit charge. We also discuss the optimum choice of retarding potentials in future flights of MUDD probes. By launching 2 to 3 mechanically identical MUDD probes but with different retarding potentials, we will obtain a much more detailed and reliable fragment (MSP) size distribution.
Heteroclinic tangle phenomena in nanomagnets subject to time-harmonic excitations
Authors: Serpico C. , Quercia A. , Bertotti G. , d'Aquino M. , Mayergoyz I. , Perna S. , Ansalone P.
Published: March 2015

Magnetization dynamics in uniformly magnetized nanomagnets excited by time-harmonic (AC) external fields or spin-polarized injected currents is considered. The analysis is focused on the behaviour of the AC-excited dynamics near saddle equilibria. It turns out that this dynamics has a chaotic character at moderately low power level. This chaotic and fractal nature is due to the phenomenon of heteroclinic tangle which is produced by the combined effect of AC-excitations and saddle type dynamics. By using the perturbation technique based on Melnikov function, analytical formulas for the threshold AC excitation amplitudes necessary to create the heteroclinic tangle are derived. Both the cases of AC applied fields and AC spin-polarized injected currents are treated. Then, by means of numerical simulations, we show how heteroclinic tangle is accompanied by the erosion of the safe basin around the stable regimes.
Issues in measure-preserving three dimensional flow integrators: Self-adjointness, reversibility, and non-uniform time stepping
Authors: Finn John M.
Published: March 2015

Properties of integration schemes for solenoidal fields in three dimensions are studied, with a focus on integrating magnetic field lines in a plasma using adaptive time stepping. It is shown that implicit midpoint (IM) and a scheme we call three-dimensional leapfrog (LF) can do a good job (in the sense of preserving KAM tori) of integrating fields that are reversible, or (for LF) have a “special divergence-free” (SDF) property. We review the notion of a self-adjoint scheme, showing that such schemes are at least second order accurate and can always be formed by composing an arbitrary scheme with its adjoint. We also review the concept of reversibility, showing that a reversible but not exactly volume-preserving scheme can lead to a fractal invariant measure in a chaotic region, although this property may not often be observable. We also show numerical results indicating that the IM and LF schemes can fail to preserve KAM tori when the reversibility property (and the SDF property for LF) of the field is broken. We discuss extensions to measure preserving flows, the integration of magnetic field lines in a plasma and the integration of rays for several plasma waves. The main new result of this paper relates to non-uniform time stepping for volume-preserving flows. We investigate two potential schemes, both based on the general method of Feng and Shang [Numer. Math. 71, 451 (1995)], in which the flow is integrated in split time steps, each Hamiltonian in two dimensions. The first scheme is an extension of the method of extended phase space, a well-proven method of symplectic integration with non-uniform time steps. This method is found not to work, and an explanation is given. The second method investigated is a method based on transformation to canonical variables for the two split-step Hamiltonian systems. This method, which is related to the method of non-canonical generating functions of Richardson and Finn [Plasma Phys. Controlled Fusion 54, 014004 (2012)], appears to work very well.
Macroscopic magnetization modeling of silicon steel sheets using an assembly of six-domain particles
Authors: Ito S. , Mifune T. , Matsuo T. , Kaido C.
Published: March 2015

A simplified domain structure model having six domains is proposed for mesoscopic magnetization under cubic anisotropy. The six-domain model represents 90° and 180° domain-wall motions by the volume-ratio variations of domains. The magnetization process of grain-oriented and non-oriented silicon steel sheets is represented by the assembly of six-domain models. Simulated magnetization curves agree well with measured properties, and the effect of compressive stress is successfully reconstructed.
The effect of morphology and confinement on the high-pressure phase transition in ZnO nanostructure
Authors: Kotmool Komsilp , Bovornratanaraks Thiti , Chakraborty Sudip , Ahuja Rajeev
Published: March 2015

The transition pressure (Pt) of the B4-to-B1 phase transformation of zinc oxide nanoparticle (n-ZnO) structures was investigated in terms of their size and morphology. Nanorods, nanopencils, nanopyramids, nanowires, and nanotubes of the B4 phase in various sizes were directly built up by accounting for the atomic basis of the core and surface regions. The previously proposed transformation path was performed for constructing shapes and sizes compatible with B1 phases. Using systematic density functional theory, the surfaces were cleaved from the optimized crystal structures at different pressures in both the B4 and B1 phases. A method for calculating the surface energy at different pressures is proposed using an asymmetric slab model. Using the proposed model, the transition pressure of n-ZnO structures was found to significantly depend on their morphology and size, which is in good agreement with the available experimental reports.
Rotational stabilization of the resistive wall modes in tokamaks with a ferritic wall
Authors: Pustovitov V. D. , Yanovskiy V. V.
Published: March 2015

The dynamics of the rotating resistive wall modes (RWMs) is analyzed in the presence of a uniform ferromagnetic resistive wall with μ̂≡μ/μ0≤4 (μ is the wall magnetic permeability, and μ0 is the vacuum one). This mimics a possible arrangement in ITER with ferromagnetic steel in test blanket modules or in future experiments in JT-60SA tokamak [Y. Kamada, P. Barabaschi, S. Ishida, the JT-60SA Team, and JT-60SA Research Plan Contributors, Nucl. Fusion 53, 104010 (2013)]. The earlier studies predict that such a wall must provide a destabilizing influence on the plasma by reducing the beta limit and increasing the growth rates, compared to the reference case with μ̂=1. This is true for the locked modes, but the presented results show that the mode rotation changes the tendency to the opposite. At μ̂>1, the rotational stabilization related to the energy sink in the wall becomes even stronger than at μ̂=1, and this “external” effect develops at lower rotation frequency, estimated as several kHz at realistic conditions. The study is based on the cylindrical dispersion relation valid for arbitrary growth rates and frequencies. This relation is solved numerically, and the solutions are compared with analytical dependences obtained for slow (s/dw≫1) and fast (s/dw≪1) “ferromagnetic” rotating RWMs, where s is the skin depth and dw is the wall thickness. It is found that the standard thin-wall modeling becomes progressively less reliable at larger μ̂, and the wall should be treated as magnetically thick. The analysis is performed assuming only a linear plasma response to external perturbations without constraints on the plasma current and pressure profiles.
Tip localization of an atomic force microscope in transmission microscopy with nanoscale precision
Authors: Baumann Fabian , Heucke Stephan F. , Pippig Diana A. , Gaub Hermann E.
Published: March 2015

Since the atomic force microscope (AFM) has evolved into a general purpose platform for mechanical experiments at the nanoscale, the need for a simple and generally applicable localization of the AFM cantilever in the reference frame of an optical microscope has grown. Molecular manipulations like in single molecule cut and paste or force spectroscopy as well as tip mediated nanolithography are prominent examples for the broad variety of applications implemented to date. In contrast to the different kinds of superresolution microscopy where fluorescence is used to localize the emitter, we, here, employ the absorbance of the tip to localize its position in transmission microscopy. We show that in a low aperture illumination, the tip causes a significant reduction of the intensity in the image plane of the microscope objective when it is closer than a few hundred nm. By independently varying the z-position of the sample slide, we could verify that this diffraction limited image of the tip is not caused by a near field effect but is rather caused by the absorbance of the transmitted light in the low apex needle-like tip. We localized the centroid position of this tip image with a precision of better than 6 nm and used it in a feedback loop to position the tip into nano-apertures of 110 nm radius. Single-molecule force spectroscopy traces on the unfolding of individual green fluorescent proteins within the nano-apertures showed that their center positions were repeatedly approached with very high fidelity leaving the specific handle chemistry on the tip’s surface unimpaired.
Revealing and resolving degeneracies in stretching exponents in temporally heterogeneous environments
Authors: Stokely Kevin , Manz Alyssa S. , Kaufman Laura J.
Published: March 2015

Supercooled liquids are proposed to be dynamically heterogeneous, with regions exhibiting relaxation time scales that vary in space and time. Measurement of the distribution of such time scales could be an important test of various proposed theories of vitrification. Single molecule fluorescence experiments attempt to uncover this distribution, typically by embedding single molecule probes into these systems and monitoring their individual rotational relaxations from a computed autocorrelation function (ACF). These ACFs may exhibit stretched exponential decays, with the value of the stretching exponent assumed to report the set of dynamical environments explored by the probe. Here, we use simulated trajectories of rotation to investigate how the time scale of dynamic exchange relative to underlying relaxation time scales in the system affects probe ability to report the distribution relaxation of time scales present. We find that dynamically heterogeneous regions must persist for approximately 50 times the median relaxation time scale for a single molecule to accurately report the full distribution of time scales it has experienced. In systems with faster dynamic exchange, single molecule ACFs average over successive environments, limiting the reported heterogeneity of the system. This leads to degeneracies in stretching exponent for systems with different underlying relaxation time distributions. We show that monitoring single molecule median stretching exponent as a function of trajectory length or simultaneously measuring median stretching exponent and measured relaxation time distribution at a given trajectory length can resolve these degeneracies, revealing the underlying set of relaxation times as well as median exchange time.
Experimental measurement of characteristic Ic (ε, θ, B) response in GdBa2Cu3Oδ coated conductor tapes under low magnetic field at 77 K
Authors: Shin Hyung-Seop , Dedicatoria Marlon J. , Gorospe Alking , Lee Sang-Heon
Published: March 2015

The continued development in the design technology of practical superconducting devices adopting high temperature superconductors tapes has led to a deeper understanding of their electromechanical behaviors. Rare-earth-barium-copper-oxide coated conductor (CC) tapes exhibit anisotropy of transport property (Ic) under magnetic field and its intrinsic strain effect is much significant depending on the orientation to the tape surface and the magnetic field intensity applied. Different experimental systems have already been developed to measure the relation of Ic with mechanical strain ε, magnetic field intensity B, and its angle of orientation, θ. However, few systems and instruments can measure these relationships simultaneously; either Ic-B-θ or Ic-ε-B is usually measured. In this study, a device which can measure these influences simultaneously based on a pair of permanent magnet systems was constructed and the characteristic responses of critical current Ic with strain, magnetic field, and its orientation with respect to the CC tape surface were investigated. The angular dependence of Ic with strain at 77 K in reactive co-evaporation by deposition and reaction GdBCO CC tapes has been measured using the permanent magnet system. The orientation angle of magnetic field with respect to the tape’s surface was varied by rotating the rig fixture that holds a pair of permanent magnets. The strain sensitivity of Ic at different angles under low magnetic field was evaluated. As a result, a characteristic surface Ic (ε, θ, B) has been constructed as the characteristic response of Ic with strain and varying orientation under magnetic field.
Exchange interaction energy in magnetic recording simulation
Authors: Igarashi Masukazu , Tonooka Shun , Katada Hiroyuki , Maeda Maki , Hara Miki , Wood Roger
Published: March 2015

Based on a phenomenological theory, micromagnetic simulations and experiments are used to evaluate an improved function for the exchange interaction between magnetic particles in perpendicular recording media. Assuming diluted spin layers in the particle boundary and a gradual rather than abrupt rotation of magnetization between grain cores, the exchange energy is better described by an even power series of θ, rather than a cosine function. The conventional cosine function does not have a restoring torque near θ = π and adjacent grains tend to align strictly antiparallel. In contrast, using a power series of θ, adjacent grains tend to align at a small angle away from θ = π. This gives rise to a small in-plane magnetization component and therefore a distinct peak in in-plane susceptibility is observed around H = 0. From magnetization measurements of a real medium, a peak is observed around H = 0, which matches with an assumption of 2 or 3 spin layers. In some situations, the exchange interaction between discretized cells for numerical calculation is better described by a power series rather than a cosine function.
Carbon nanotube bundles/polystyrene composites as high-performance flexible thermoelectric materials
Authors: Suemori Kouji , Watanabe Yuichi , Hoshino Satoshi
Published: March 2015

Lightweight and flexible thermoelectric devices consisting of carbon nanotube (CNT)-based materials have the potential to be used for the various applications, such as energy harvesting from the low-temperature waste heat that exists ubiquitously in living areas. Because high-performance CNT-based materials are crucial for the broad-ranging employment of CNT-based thermoelectric devices, considerable efforts are being made to improve the power-generation capability of CNT-based thermoelectric materials. Here, we report high-performance thermoelectric composites consisting of CNT bundles and polystyrene fabricated by a planetary ball milling-based dispersion technique, which allows for the direct dispersion of the CNT bundles within the polystyrene matrix without causing the disaggregation of the bundled CNTs into individual ones. The CNT-bundles/polystyrene composites reported here exhibit a power factor of 413 μW/K2·m.
Trade-off between number of conductance states and variability of conductance change in Pr0.7Ca0.3MnO3-based synapse device
Authors: Lee Daeseok , Moon Kibong , Park Jaesung , Park Sangsu , Hwang Hyunsang
Published: March 2015

The characteristics of Pr0.7Ca0.3MnO3 (PCMO)-based resistive change memory were evaluated as a synapse device for a emerging computing system inspired by a biological brain. The evaluated samples structured with various reactive top electrodes exhibited a dependence on the metal-oxide free energy. More conductance states which can improve the performance of the brain-inspired computing system were achieved in a sample having a low metal-oxide free energy. During the increase and decrease in the conductance, the low metal-oxide free energy also resulted in an asymmetric conductance change leading to degradation in the computational accuracy of the brain-inspired computing system. The results demonstrated a trade-off between the number of conductance states and the variation in the conductance change in the PCMO-based synapse device.
Metal insulator transition and magnetotransport anomalies in perovskite SrIr0.5Ru0.5O3 thin films
Authors: Biswas Abhijit , Lee Yong Woo , Kim Sang Woo , Jeong Yoon Hee
Published: March 2015

We investigated the nature of transport and magnetic properties in SrIr0.5Ru0.5O3 (SIRO), which has characteristics intermediate between a correlated non-Fermi liquid state and an itinerant Fermi liquid state, by growing perovskite thin films on various substrates (e.g., SrTiO3 (001), (LaAlO3)0.3(Sr2TaAlO6)0.7 (001), and LaAlO3 (001)). We observed systematic variation of underlying substrate dependent metal-to-insulator transition temperatures (TMIT ∼ 80 K on SrTiO3, ∼90 K on (LaAlO3)0.3(Sr2TaAlO6)0.7, and ∼100 K on LaAlO3) in resistivity. At temperature 300 K ≥ T ≥ TMIT, SIRO is metallic and its resistivity follows a T3/2 power law, whereas insulating nature at T < TMIT is due to the localization effect. Magnetoresistance (MR) measurement of SIRO on SrTiO3 (001) shows negative MR at T < 25 K and positive MR at T > 25 K, with negative MR ∝ B1/2 and positive MR ∝ B2; consistent with the localized-to-normal transport crossover dynamics. Furthermore, observed spin glass like behavior of SIRO on SrTiO3 (001) at T < 25 K in the localized regime validates the hypothesis that (Anderson) localization favors glassy ordering. These remarkable features provide a promising approach for future applications and of fundamental interest in oxide thin films.
Spin wave spectra in perpendicularly magnetized permalloy rings
Authors: Zhou X. , Ding J. , Kostylev M. , Adeyeye A. O.
Published: March 2015

The dynamic behavior of perpendicularly magnetized permalloy circular rings is systematically investigated as a function of film thickness using broadband field modulated ferromagnetic resonance spectroscopy. We observed the splitting of one spin wave mode into a family of dense resonance peaks for the rings, which is markedly different from the single mode observed for continuous films of the same thickness. As the excitation frequency is increased, the mode family observed for the rings gradually converges into one mode. With the increase in the film thickness, a sparser spectrum of modes is observed. Our experimental results are in qualitative agreement with the dynamic micromagnetic simulations.
Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications
Authors: Di Pendina G. , Zianbetov E. , Beigne E.
Published: March 2015

Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes.
Low-loss, submicron chalcogenide integrated photonics with chlorine plasma etching
Authors: Chiles Jeff , Malinowski Marcin , Rao Ashutosh , Novak Spencer , Richardson Kathleen , Fathpour Sasan
Published: March 2015

A chlorine plasma etching-based method for the fabrication of high-performance chalcogenide-based integrated photonics on silicon substrates is presented. By optimizing the etching conditions, chlorine plasma is employed to produce extremely low-roughness etched sidewalls on waveguides with minimal penalty to propagation loss. Using this fabrication method, microring resonators with record-high intrinsic Q-factors as high as 450 000 and a corresponding propagation loss as low as 0.42 dB/cm are demonstrated in submicron chalcogenide waveguides. Furthermore, the developed chlorine plasma etching process is utilized to demonstrate fiber-to-waveguide grating couplers in chalcogenide photonics with high power coupling efficiency of 37% for transverse-electric polarized modes.
Water-responsive carbon nanotubes for selective detection of toxic gases
Authors: Mukherjee Soumalya , Sakorikar Tushar , Mukherjee Anwesha , Misra Abha
Published: March 2015

Ammonia plays an important role in our daily lives and hence its quantitative and qualitative sensing has become necessary. Bulk structure of carbon nanotubes (CNTs) has been employed to detect the gas concentration of 10 ppm. Hydrophobic CNTs were turned to hydrophilic via the application of a ramp electric field that allowed confinement of a controlled amount of water inside CNT microstructure. These samples were then also used to detect different gases. A comparative study has been performed for sensing three reducing gases, namely, ammonia, sulphur-di-oxide, and hydrogen sulphide to elaborate the selectivity of the sensor. A considerable structural bending in the bulk CNT was observed on evaporation of the confined water, which can be accounted to the zipping of individual nanotubes. However, the rate of the stress induced on these bulk microstructures increased on the exposure of ammonia due to the change in the surface tension of the confined solvent. A prototype of an alarm system has been developed to illustrate sensing concept, wherein the generated stress in the bulk CNT induces a reversible loss in electrical contact that changes the equivalent resistance of the electrical circuit upon exposure to the gas.
Off-stoichiometric silver antimony telluride: An experimental study of transport properties with intrinsic and extrinsic doping
Authors: Nielsen Michele D. , Jaworski Christopher M. , Heremans Joseph P.
Published: March 2015

AgSbTe2 is a thermoelectric semiconductor with an intrinsically low thermal conductivity and a valence band structure that is favorable to obtaining a high thermoelectric figure of merit zT. It also has a very small energy gap Eg ∼ 7.6 ± 3 meV. As this gap is less than the thermal excitation energy at room temperature, near-intrinsic AgSbTe2 is a two carrier system having both holes (concentration p) and electrons (n). Good thermoelectric performance requires heavy p-type doping (p > > n). This can be achieved with native defects or with extrinsic doping, e.g. with transition metal element. The use of defect doping is complicated by the fact that many of the ternary Ag-Sb-Te and pseudo-binary Sb2Te3-Ag2Te phase diagrams are contradictory. This paper determines the compositional region most favorable to creating a single phase material. Through a combination of intrinsic and extrinsic doping, values of zT > 1 are achieved, though not on single-phased material. Additionally, we show that thermal conductivity is not affected by defects, further demonstrating that the low lattice thermal conductivity of I-V-VI2 materials is due to an intrinsic mechanism, insensitive to changes in defect structure.
Morphology and DNA barcodes reveal the presence of the non-native land planarian Obama marmorata (Platyhelminthes : Geoplanidae) in Europe
Authors: Lago-Barcia Domingo , Fernández-Álvarez Fernando A. , Negrete Lisandro , Brusa Francisco , Damborenea Cristina , Grande Cristina , Noreña Carolina
Published: March 2015

We report for the first time the occurrence of Obama marmorata in the Iberian Peninsula as an introduced species from the Neotropical Region. The species is also reported for the first time in Argentina. The identification was made on the basis of morphological evidence. The divergence levels of a fragment of the mitochondrial cytochromec oxidaseI gene from Argentinean and Iberian samples were studied. The morphology of samples from the two regions was the same and matched the original description of the species. A DNA barcoding matrix was constructed using new sequences from O. marmorata and sequences of related species taken from GenBank. Among the Geoplanidae, interspecific divergence ranged between 3.3 and 14.4%, while intraspecific divergence percentages were 0–1.2%, signalling the presence of a DNA barcoding gap. All O. marmorata sequences, irrespective of their geographic origin, form a well supported clade with an intraspecific divergence of 0–0.9 (average = 0.4%). These results indicate the utility of DNA barcoding to discover allochthonous species in this group of organisms.
Recovery of small rodent populations after population collapse
Authors: Hein S. , Jacob J.
Published: March 2015

In this review we summarise published knowledge regarding small mammal population recovery following sudden population collapse, regardless as to whether the collapse is caused by natural or man-made events. We determine recovery mechanisms, recovery time and recovery rate, and suggest how to adapt and optimise current methods to regulate small mammal population size, for pest management and/or conservation. It is vital that the principles underlying the recovery mechanisms are known for both pest control and conservation to align management methods to either maintain animal numbers at a permanent minimum level or increase population size. Collapses can be caused naturally, as in the declining phase of multi-annual fluctuations and after natural disasters, or by man-made events, such as pesticide application. In general, there are three ways population recovery can occur: (1) in situ survival and multiplication of a small remaining fraction of the population; (2) immigration; or (3) a combination of the two. The recovery mechanism strongly depends on life history strategy, social behaviour and density-dependent processes in population dynamics of the species in question. In addition, the kind of disturbance, its intensity and spatial scale, as well as environmental circumstances (e.g. the presence and distance of refuge areas) have to be taken into account. Recovery time can vary from a couple of days to several years depending on the reproductive potential of the species and the type of disturbances, regardless of whether the collapse is man made or natural. Ultimately, most populations rebound to levels equal to numbers before the collapse. Based on current knowledge, case-by-case decisions seem appropriate for small-scale conservation. For pest control, a large-scale approach seems necessary. Further investigations are required to make sound, species-specific recommendations.
Changes in Sex Steroids, Growth Hormone, and Insulin-Like Growth Factor-I during Ovarian Development in Rainbow Trout Cultured in a Water Recirculating System with Continuous Light
Authors: Weber Gregory M , Davidson John W , Kenney P Brett , Good Christopher M , Manor Meghan L , Welsh Carla , Aussanasuwannakul Aunchalee , Summerfelt Steven T
Published: March 2015

Female Rainbow Trout Oncorhynchus mykiss were cultured within a freshwater recirculating aquaculture system under 24-h constant lighting in 13°C water and fed every 6 h to near satiation. An opaque roof allowed surface light intensity to vary between <200 and about 1,500 lx. During months 14–26 posthatch we examined changes in plasma concentrations of testosterone (T), estradiol-17β (E2), the maturation inducing steroid (MIS) 17α,20β-dihydroxy-4-pregnen-3-one (17,20βP), growth hormone (GH), and insulin-like growth factor-I (IGF-I). Oocyte diameter was variable at the start of the study, most averaging <1 mm; diameter increased to above 3.2 mm in the final 2 months, with migrating germinal vesicles indicating they were postvitellogenic. Some ovaries exhibited atresia, and no fish ovulated, suggesting some reproductive dysfunction. Testosterone and E2 began increasing between months 16 and 18, and although T continued to increase throughout the study, E2 changed little after month 20. The MIS 17,20βP, remained near or below detection. Plasma GH remained relatively unchanged although values trended slightly higher during the final 4 months, GH being significantly greater at months 22, 24 and 26 than at month 16. Plasma IGF-I was higher at the first time point, month 14 posthatch than at months 20, 24, 25, and 26. In summary, gradual changes in growth and fillet quality attributes during gonadal development were accompanied by gradual changes in hormone levels, but no clear changes in hormones were associated with rapid changes in product quality traits observed around months 24–26.
Dynamics of the square mapping on the ring of 𝑝-adic integers
Authors: Fan Shilei , Liao Lingmin
Published: March 2015

For each prime number

p
p

, the dynamical behavior of the square mapping on the ring

Z

p

\mathbb {Z}_p

of

p
p

-adic integers is studied. For

p
=
2

p=2

, there are only attracting fixed points with their attracting basins. For

p
≥
3

p\geq 3

, there are a fixed point

0
0

with its attracting basin, finitely many periodic points around which there are countably many minimal components and some balls of radius

1

/

p

1/p

being attracting basins. All these minimal components are precisely exhibited for different primes

p
p

.
QSLiMFinder: improved short linear motif prediction using specific query protein data
Authors: Palopoli Nicolas , Lythgow Kieren T. , Edwards Richard J.
Published: March 2015

Motivation: The sensitivity of de novo short linear motif (SLiM) prediction is limited by the number of patterns (the motif space) being assessed for enrichment. QSLiMFinder uses specific query protein information to restrict the motif space and thereby increase the sensitivity and specificity of predictions.

Results: QSLiMFinder was extensively benchmarked using known SLiM-containing proteins and simulated protein interaction datasets of real human proteins. Exploiting prior knowledge of a query protein likely to be involved in a SLiM-mediated interaction increased the proportion of true positives correctly returned and reduced the proportion of datasets returning a false positive prediction. The biggest improvement was seen if a short region of the query protein flanking the interaction site was known.

Availability and implementation: All the tools and data used in this study, including QSLiMFinder and the SLiMBench benchmarking software, are freely available under a GNU license as part of SLiMSuite, at: http://bioware.soton.ac.uk.

Contact:  richard.edwards@unsw.edu.au

Supplementary information:  Supplementary data are available at Bioinformatics online.
The initial mass function of early-type galaxies: no correlation with [Mg/Fe]
Authors: La Barbera Francesco , Ferreras Ignacio , Vazdekis Alexandre
Published: March 2015

The initial mass function (IMF) of early-type galaxies (ETGs) has been found to feature systematic variations by both dynamical and spectroscopic studies. In particular, spectral line strengths, based on gravity-sensitive features, suggest an excess of low-mass stars in massive ETGs, i.e. a bottom-heavy IMF. The physical drivers of IMF variations are currently unknown. The abundance ratio of α elements, such as [Mg/Fe], has been suggested as a possible driver of the IMF changes, although dynamical constraints do not support this claim. In this letter, we take advantage of the large Sloan Digital Sky Survey data base. Our sample comprises 24 781 high-quality spectra, covering a large range in velocity dispersion (100 < σ0 < 320  km s−1) and abundance ratio ( − 0.1 < [Mg/Fe] < +0.4). The large volume of data allows us to stack the spectra at fixed values of σ0 and [Mg/Fe]. Our analysis – based on gravity-sensitive line strengths – gives a strong correlation with central velocity dispersion and a negligible variation with [Mg/Fe] at fixed σ0. This result is robust against individual elemental abundance variations, and seems not to raise any apparent inconsistency with the alternative method based on galaxy dynamics.
On the origin of γ-ray emission in η Carina
Authors: Ohm S. , Zabalza V. , Hinton J. A. , Parkin E. R.
Published: March 2015

η Car is the only colliding-wind binary for which high-energy γ rays are detected. Although the physical conditions in the shock region change on time-scales of hours to days, the variability seen at GeV energies is weak and on significantly longer time-scales. The γ-ray spectrum exhibits two features that can be interpreted as emission from the shocks on either side of the contact discontinuity. Here, we report on the first time-dependent modelling of the non-thermal emission in η Car. We find that emission from primary electrons is likely not responsible for the γ-ray emission, but accelerated protons interacting with the dense wind material can explain the observations. In our model, efficient acceleration is required at both shocks, with the primary side acting as a hadron calorimeter, whilst on the companion side acceleration is limited by the flow time out of the system, resulting in changing acceleration conditions. The system therefore represents a unique laboratory for the exploration of hadronic particle acceleration in non-relativistic shocks.