bluuebunny/crossref_metadata_2025 huggingface dataset:
A new glycation product ‘norpronyl-lysine,’ and direct characterization of cross linking and other glycation adducts: NMR of model compounds and collagen
Authors: Bullock Peter T. B. , Reid David G. , Ying Chow W. , Lau Wendy P. W. , Duer Melinda J.
Published: February 2014

NMR is ideal for characterizing non-enzymatic protein glycation, including AGEs (advanced glycation endproducts) underlying tissue pathologies in diabetes and ageing. Ribose, R5P (ribose-5-phosphate) and ADPR (ADP-ribose), could be significant and underinvestigated biological glycating agents especially in chronic inflammation. Using [U-13C]ribose we have identified a novel glycoxidation adduct, 5-deoxy-5-desmethylpronyl-lysine, ‘norpronyl-lysine’, as well as numerous free ketones, acids and amino group reaction products. Glycation by R5P and ADPR proceeds rapidly with R5P generating a brown precipitate with PLL (poly-L-lysine) within hours. ssNMR (solid-state NMR) 13C–13C COSY identifies several crosslinking adducts such as the newly identified norpronyl-lysine, in situ, from the glycating reaction of 13C5-ribose with collagen. The same adducts are also identifiable after reaction of collagen with R5P. We also demonstrate for the first time bio-amine (spermidine, N-acetyl lysine, PLL) catalysed ribose 2-epimerization to arabinose at physiological pH. This work raises the prospect of advancing understanding of the mechanisms and consequences of glycation in actual tissues, in vitro or even ex vivo, using NMR isotope-labelled glycating agents, without analyses requiring chemical or enzymatic degradations, or prior assumptions about glycation products.
Non-canonical signalling and roles of the vasoactive peptides angiotensins and kinins
Authors: Costa-Neto Claudio M. , Duarte Diego A. , Lima Vanessa , Maria Andrea G. , Prando Érika C. , Rodríguez Deisy Y. , Santos Geisa A. , Souza Pedro P. C. , Parreiras-e-Silva Lucas T.
Published: February 2014

GPCRs (G-protein-coupled receptors) are among the most important targets for drug discovery due to their ubiquitous expression and participation in cellular events under both healthy and disease conditions. These receptors can be activated by a plethora of ligands, such as ions, odorants, small ligands and peptides, including angiotensins and kinins, which are vasoactive peptides that are classically involved in the pathophysiology of cardiovascular events. These peptides and their corresponding GPCRs have been reported to play roles in other systems and under pathophysiological conditions, such as cancer, central nervous system disorders, metabolic dysfunction and bone resorption. More recently, new mechanisms have been described for the functional regulation of GPCRs, including the transactivation of other signal transduction receptors and the activation of G-protein-independent pathways. The existence of such alternative mechanisms for signal transduction and the discovery of agonists that can preferentially trigger one signalling pathway over other pathways (called biased agonists) have opened new perspectives for the discovery and development of drugs with a higher specificity of action and, therefore, fewer side effects. The present review summarizes the current knowledge on the non-canonical signalling and roles of angiotensins and kinins.
Spectrally encoded code‐division multiple access for cognitive radio networks
Authors: Najafi Shahla , Shayesteh Mahrokh G.
Published: February 2014

Recent studies have revealed that spectrum congestion is due to the inefficient usage of spectrum against the availability. Cognitive radio is viewed as an approach for improving the utilisation of radio spectrum. The spectrally encoded (spread‐time) code‐division multiple access (SE‐CDMA) technique (which is regarded as the dual of spread spectrum CDMA) is considered and its performance in cognitive radio networks is studied. In cognitive network spectrum, overlay and underlay techniques are employed to enable the primary and secondary users to coexist while improving the overall spectrum efficiency. It is shown that SE‐CDMA provides considerable flexibility to design overlay and underlay waveforms that are scenario‐dependent. The performance of SE‐CDMA method is evaluated in additive white Gaussian noise and fading channels in terms of both primary and secondary users. Moreover, its performance is compared with cognitive radio using soft‐decision spectrally modulated spectrally encoded waveforms. The results indicate the efficiency of SE‐CDMA.
Adaptive rate and power transmission in spectrum‐sharing systems with statistical interference constraint
Authors: Khederzadeh Reza , Farrokhi Hamid
Published: February 2014

The present study attempted to investigate the capacity gains in a spectrum‐sharing system where the transmit power and rate of the secondary user (SU) are adapted based on the spectrum sensing information about activity of primary user (PU) and statistical channel fading gain between the SU transmitter (SUT) and PU receiver (PUR). It was assumed that the SU can use the spectrum band originally allocated to PU, based on the definition that when the PU is present in the spectrum band, the SU must consider the peak transmit power and statistical interference constraints. In addition, when the PU is absent at the spectrum band, the SU can only consider the peak transmit power constraint. The main advantage of using statistical interference constraint is that it does not require the instantaneous feedback channel between SUT and PUR. Furthermore, to maximise the achievable capacity of the SU, the average transmit power was first calculated. Then the adaptive rate and power policy were inspected for maximising the achievable capacity under said constraints and bit error rate requirements in multilevel quadrature amplitude modulation. Numerical and comparison results representing the efficiency of the proposed system are also provided.
New accelerated graph‐based method of image segmentation applying minimum spanning tree
Authors: Fabijańska Anna , Gocławski Jarosław
Published: February 2014

In this paper problem of graph based image segmentation is considered. In particular, attention is paid to minimal spanning tree based algorithm proposed by Felzenszwalb and Huttenlocher (FH). Although the method yields high quality results for various classes of images, its application is limited mainly to off‐line processing. Its due to the very long execution time of the FH method, which in the case of high resolution images, requires processing of millions of vertices and edges contained within the resulting graph. Therefore, some improvements to the FH method are proposed in this paper. The modifications aim at the reduction of algorithm execution time and the usage of computer host memory. These goals are achieved both by reducing the size of input image graph and by applying the methods of GPU parallel computing at initial stages of the algorithm. As the reduction of graph size is obtained by processing meta‐pixels representing homogenous regions, the new method is most suitable for the segmentation of images including rare, structurally complex objects distributed over nonuniform background. Results obtained by the introduced approach are compared with the results of the original FH method and other popular graph‐based approaches to image segmentation. The comparison includes both the accuracy of image segmentation and the execution time. Analysis of the results clearly shows, that the proposed approach in many cases can significantly accelerate segmentation process without a noticeable loss of image segmentation quality.
Mitigation of windfarm power fluctuation by adaptive linear neuron‐based power tracking method with flexible learning rate
Authors: Jannati Mohsen , Hosseinian S.H. , Vahidi Behrooz , Li Guo‐Jie
Published: February 2014

Most wind turbine generators installed in large windfarms are of variable speed types operating at the maximum power point tracking mode to generate the maximum amount of power. Owing to this fact and regarding the random nature of the windspeed, the output power of the windfarm fluctuates. Fluctuating power is a serious problem for high capacity power plants and should be smoothed. As an effective factor on the required battery energy storage system (BESS) capacity value, tracking is the most important part performed by a coordinated control system in the power smoothing process. An ADAptive LInear NEuron (ADALINE)‐based power tracking method with a flexible learning rate is proposed in this study. Furthermore, a particle swarm optimisation‐based calculation of the learning rate is presented for optimising the proposed tracking method which reduces the required BESS capacity and the investment cost. Moreover, a charging/discharging algorithm for the BESS units is proposed which decreases the number of required BESS units and increases their useful life by reducing the switching activity as well. To evaluate the performance of the proposed coordinated control approach, the real output data of a 99 MW windfarm are tested. The simulation results verify the effectiveness of the proposed approach.
Clutter cancellation in passive radar using GSM broadcast channels
Authors: Demissie Bruno
Published: February 2014

This study focuses on passive coherent location using global system for mobile communications base stations transmitting mainly dummy bursts in idle mode. The authors present adaptive delay line canceller techniques to suppress the zero‐Doppler direct path and its clutter almost down to the receiver noise level. The proposed approaches offer the following two advantages compared with the other clutter cancellation techniques: they are fail‐safe with respect to the errors in the reference signal extraction simply because they do not require any knowledge of the reference signal and they even work in severely non‐stationary clutter conditions. The effectiveness of the approaches is demonstrated by means of measurements recorded with an experimental passive bistatic radar system.
Theoretical studies of optical gain tuning by hydrostatic pressure in GaInNAs/GaAs quantum wells
Authors: Gladysiewicz M. , Kudrawiec R. , Wartak M. S.
Published: February 2014

In order to describe theoretically the tuning of the optical gain by hydrostatic pressure in GaInNAs/GaAs quantum wells (QWs), the optical gain calculations within kp approach were developed and applied for N-containing and N-free QWs. The electronic band structure and the optical gain for GaInNAs/GaAs QW were calculated within the 10-band kp model which takes into account the interaction of electron levels in the QW with the nitrogen resonant level in GaInNAs. It has been shown that this interaction increases with the hydrostatic pressure and as a result the optical gain for GaInNAs/GaAs QW decreases by about 40% and 80% for transverse electric and transverse magnetic modes, respectively, for the hydrostatic pressure change from 0 to 40 kilobars. Such an effect is not observed for N-free QWs where the dispersion of electron and hole energies remains unchanged with the hydrostatic pressure. This is due to the fact that the conduction and valence band potentials in GaInAs/GaAs QW scale linearly with the hydrostatic pressure.
Analytical solution for capacitance calculation of a curved patch capacitor that conforms to the curvature of a homogeneous cylindrical dielectric rod
Authors: Chen Tianming , Bowler John R. , Bowler Nicola
Published: February 2014

This Letter presents an analytical expression for the capacitance of a curved patch capacitor whose electrodes conform to the curvature of a long, homogeneous, cylindrical dielectric rod. The capacitor is composed of two infinitely long curved electrodes, symmetrically placed about a diameter of the cylinder cross-section. The resulting capacitance per unit length depends on both the dielectric properties of the material under test and the capacitor configuration. A practical capacitance measurement is also presented, with appropriately guarded finite electrodes. Very good agreement between measured and theoretically predicted capacitances were observed, to within 2.4 percent. The analytical result presented in this Letter can be applied for extremely rapid evaluation of rod permittivity from measured capacitance.
Balanced double-loop mesoscopic interferometer based on Josephson proximity nanojunctions
Authors: Ronzani Alberto , Altimiras Carles , Giazotto Francesco
Published: February 2014

We report on the fabrication and characterization of a two-terminal mesoscopic interferometer based on three V/Cu/V Josephson junctions having nanoscale cross-section. The junctions have been arranged in a double-ring geometry realized by metallic thin film deposition through a suspended mask defined by electron beam lithography. Although a significant amount of asymmetry between the critical current of each junction is observed, we show that the interferometer is able to suppress the supercurrent to a level lower than 6 parts per thousand, being here limited by measurement resolution. The present nano-device is suitable for low-temperature magnetometric and gradiometric measurements over the micrometric scale.
Characterization of in situ SiNx thin film grown on AlN/GaN heterostructure by metal-organic chemical vapor deposition
Authors: Lu Xing , Ma Jun , Jiang Huaxing , May Lau Kei
Published: February 2014

We report an investigation of in situ SiNx gate dielectric grown on AlN/GaN heterostructures by metal-organic chemical vapor deposition. It is revealed that the in situ SiNx is Si-rich, with a N/Si ratio of 1.21 and a relatively high effective dielectric constant of ∼8.3. The 7 nm in situ SiNx film exhibited a large resistivity of >1014 Ω · cm and a breakdown field of 5.7 MV/cm. Furthermore, interface trapping effects in the in situ SiNx/AlN/GaN heterostructures were investigated by frequency dependent conductance analysis.
Fermi-dirac and random carrier distributions in quantum dot lasers
Authors: Hutchings M. , O'Driscoll I. , Smowton P. M. , Blood P.
Published: February 2014

Using experimental gain and emission measurements as functions of temperature, a method is described to characterise the carrier distribution of radiative states in a quantum dot (QD) laser structure in terms of a temperature. This method is independent of the form of the inhomogeneous dot distribution. A thermal distribution at the lattice temperature is found between 200 and 300 K. Below 200 K the characteristic temperature exceeds the lattice temperature and the distribution becomes random below about 60 K. This enables the temperature range for which Fermi-Dirac statistics are applicable in QD laser threshold calculations to be identified.
Ultra-low propagation losses in fresnoite-type precipitated crystallized glasses
Authors: Yamazaki Yoshiki , Takahashi Yoshihiro , Ihara Rie , Fujiwara Takumi
Published: February 2014

The propagation losses for fresnoite-phase crystallized glasses fabricated from 35BaO–15TiO2–50GeO2, 28BaO–18TiO2–54SiO2, and 35SrO–20TiO2–45SiO2 (STS45) glasses using a cut-back technique are reported. The values are comparable with those for LiNbO3 waveguide single crystals and transparent Y3Al5O12 ceramics. In addition, the propagation loss data indicate that the losses depend on the relationship between the polarization direction and crystal growth direction. The lowest propagation loss value (0.6 dB/cm) was measured for the STS45 crystallized glass; this value is the lowest value ever reported for an oriented crystallized glass.
Fluorescence spectra shape based dynamic thermometry
Authors: Liu Liwang , Creten Sebastiaan , Firdaus Yuliar , Agustin Flores Cuautle Jose Jesus , Kouyaté Mansour , Van der Auweraer Mark , Glorieux Christ
Published: February 2014

An entirely optical, dynamic thermometry technique based on the temperature dependence of a fluorescence spectrum is presented. Different from conventional intensity-based fluorescence thermometry, in this work, neural network recognition is employed to extract the sample temperature from the magnitude and shape of recorded fluorescence spectra. As a demonstration to determine the depth profile of dynamical temperature variations and of the thermal and optical properties of semitransparent samples, in-depth photothermally induced periodical temperature oscillations of a rhodamine B and copper chloride dyed glycerol sample were measured with an accuracy of 4.2 mK·Hz−1/2 and fitted well by a 1D thermal diffusion model.
A method for the frequency control in time-resolved two-dimensional gigahertz surface acoustic wave imaging
Authors: Kaneko Shogo , Tomoda Motonobu , Matsuda Osamu
Published: February 2014

We describe an extension of the time-resolved two-dimensional gigahertz surface acoustic wave imaging based on the optical pump-probe technique with periodic light source at a fixed repetition frequency. Usually such imaging measurement may generate and detect acoustic waves with their frequencies only at or near the integer multiples of the repetition frequency. Here we propose a method which utilizes the amplitude modulation of the excitation pulse train to modify the generation frequency free from the mentioned limitation, and allows for the first time the discrimination of the resulted upper- and lower-side-band frequency components in the detection. The validity of the method is demonstrated in a simple measurement on an isotropic glass plate covered by a metal thin film to extract the dispersion curves of the surface acoustic waves.
Red blood cell dynamics in polymer brush-coated microcapillaries: A model of endothelial glycocalyx in vitro
Authors: Lanotte Luca , Tomaiuolo Giovanna , Misbah Chaouqi , Bureau Lionel , Guido Stefano
Published: February 2014

The confined flow of red blood cells (RBCs) in microvasculature is essential for oxygen delivery to body tissues and has been extensively investigated in the literature, both in vivo and in vitro. One of the main problems still open in microcirculation is that flow resistance in microcapillaries in vivo is higher than that in vitro. This discrepancy has been attributed to the glycocalyx, a macromolecular layer lining the inner walls of vessels in vivo, but no direct experimental evidence of this hypothesis has been provided so far. Here, we investigate the flow behavior of RBCs in glass microcapillaries coated with a polymer brush (referred to as “hairy” microcapillaries as opposed to “bare” ones with no coating), an experimental model system of the glycocalyx. By high-speed microscopy imaging and image analysis, a velocity reduction of RBCs flowing in hairy microcapillaries as compared to bare ones is indeed found at the same pressure drop. Interestingly, such slowing down is larger than expected from lumen reduction due to the polymer brush and displays an on-off trend with a threshold around 70 nm of polymer brush dry thickness. Above this threshold, the presence of the polymer brush is associated with an increased RBC deformation, and RBC velocity is independent on polymer brush thickness (at the same pressure drop). In conclusion, this work provides direct support to the hypothesis that the glycocalyx is the main factor responsible of the higher flow resistance found in microcapillaries in vivo.
Effects of a static electric field on two-color photoassociation between different atoms
Authors: Chakraborty Debashree , Deb Bimalendu
Published: February 2014

We study non-perturbative effects of a static electric field on two-color photoassociation of different atoms. A static electric field induces anisotropy in scattering between two different atoms and hybridizes field-free rotational states of heteronuclear dimers or polar molecules. In a previous paper [D. Chakraborty et al., J. Phys. B 44, 095201 (2011)], the effects of a static electric field on one-color photoassociation between different atoms has been described through field-modified ground-state scattering states, neglecting electric field effects on heteronuclear diatomic bound states. To study the effects of a static electric field on heteronuclear bound states, and the resulting influence on Raman-type two-color photoassociation between different atoms in the presence of a static electric field, we develop a non-perturbative numerical method to calculate static electric field-dressed heteronuclear bound states. We show that the static electric field induced scattering anisotropy as well as hybridization of rotational states strongly influence two-color photoassociation spectra, leading to significant enhancement in PA rate and large shift. In particular, for static electric field strengths of a few hundred kV/cm, two-color PA rate involving high-lying bound states in electronic ground-state increases by several orders of magnitude even in the weak photoassociative coupling regime.
Status of surface conduction in topological insulators
Authors: Barua Sourabh , Rajeev K. P.
Published: February 2014

In this report, we scrutinize the thickness dependent resistivity data from the recent literature on electrical transport measurements in topological insulators. A linear increase in resistivity with increase in thickness is expected in the case of these materials since they have an insulating bulk and a conducting surface. However, such a trend is not seen in the resistivity versus thickness data for all the cases examined, except for some samples, where it holds for a range of thickness.
Omnidirectional mirror based on Bragg stacks with a periodic gain-loss modulation
Authors: Manzanares-Martinez Jesus , Ham-Rodriguez Carlos Ivan , Moctezuma-Enriquez Damian , Manzanares-Martinez Betsabe
Published: February 2014

In this work we demonstrate that a Bragg Stack with a periodic gain-loss modulation can function as an Omnidirectional Mirror (OM) with complete reflection at any angle of incidence irrespective of the light polarization. The Bragg Stack is composed by the periodic variation of two layers with the same value of the real part of the refractive index (nr) and a periodic modulation in the imaginary part (ni). The origin of the band gaps is due to the interference of complex waves with propagating and evanescent fields in each layer. It is found that the band gaps are wider as the contrast ni/nr increases. We have found the ambient conditions to obtain an OM considering an auxiliary medium n′ external to the Bragg Stack.
Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations
Authors: Carvalho Pedro J. , Ventura Sónia P. M. , Batista Marta L. S. , Schröder Bernd , Gonçalves Fernando , Esperança José , Mutelet Fabrice , Coutinho João A. P.
Published: February 2014

The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed.
Airfoil longitudinal gust response in separated vs. attached flows
Authors: Granlund K. , Monnier B. , Ol M. , Williams D.
Published: February 2014

Airfoil aerodynamic loads are expected to have quasi-steady, linear dependence on the history of input disturbances, provided that small-amplitude bounds are observed. We explore this assertion for the problem of periodic sinusoidal streamwise gusts, by comparing experiments on nominally 2D airfoils in temporally sinusoidal modulation of freestream speed in a wind tunnel vs. sinusoidal displacement of the airfoil in constant freestream in a water tunnel. In the wind tunnel, there is a streamwise unsteady pressure gradient causing a buoyancy force, while in the water tunnel one must subtract the inertial load of the test article. Both experiments have an added-mass contribution to aerodynamic force. Within measurement resolution, lift and drag, fluctuating and mean, were in good agreement between the two facilities. For incidence angle below static stall, small-disturbance theory was found to be in good agreement with measured lift history, regardless of oscillation frequency. The circulatory component of fluctuating drag was found to be independent of oscillation frequency. For larger incidence angles, there is marked departure between the measured lift history and that predicted from Greenberg's formula. Flow visualization shows coupling between bluff-body shedding and motion-induced shedding, identifiable with lift cancellation or augmentation, depending on the reduced frequency. Isolating the buoyancy effect in the wind tunnel and dynamic tares in the water tunnel, and theoretical calculation of apparent-mass in both cases, we arrive at good agreement in measured circulatory contribution between the two experiments whether the flow is attached or separated substantiating the linear superposition of the various constituents to total lift and drag, and supporting the idea that aerodynamic gust response can legitimately be studied in a steady freestream by oscillating the test article.
The effects of buffer layers on the performance and stability of flexible InGaZnO thin film transistors on polyimide substrates
Authors: Ok Kyung-Chul , Ko Park Sang-Hee , Hwang Chi-Sun , Kim H. , Soo Shin Hyun , Bae Jonguk , Park Jin-Seong
Published: February 2014

We demonstrated the fabrication of flexible amorphous indium gallium zinc oxide thin-film transistors (TFTs) on high-temperature polyimide (PI) substrates, which were debonded from the carrier glass after TFT fabrication. The application of appropriate buffer layers on the PI substrates affected the TFT performance and stability. The adoption of the SiNx/AlOx buffer layers as water and hydrogen diffusion barriers significantly improved the device performance and stability against the thermal annealing and negative bias stress, compared to single SiNx or SiOx buffer layers. The substrates could be bent down to a radius of curvature of 15 mm and the devices remained normally functional.
Universality for a global property of the eigenvectors of Wigner matrices
Authors: Bao Zhigang , Pan Guangming , Zhou Wang
Published: February 2014

Let Mn be an n×n real (resp. complex) Wigner matrix and \documentclass[12pt]{minimal}\begin{document}$U_n\Lambda _n U_n^*$\end{document}UnΛnUn* be its spectral decomposition. Set \documentclass[12pt]{minimal}\begin{document}$(y_1,y_2\cdots ,y_n)^T=U_n^*\mathbf {x}$\end{document}(y1,y2⋯,yn)T=Un*x, where x = (x1, x2, ⋅⋅⋅, xn)T is a real (resp. complex) unit vector. Under the assumption that the elements of Mn have 4 matching moments with those of GOE (resp. GUE), we show that the process \documentclass[12pt]{minimal}\begin{document}$X_n(t)=\sqrt{\frac{\beta n}{2}}\sum _{i=1}^{\lfloor nt\rfloor }(|y_i|^2-\frac{1}{n})$\end{document}Xn(t)=βn2∑i=1⌊nt⌋(|yi|2−1n) converges weakly to the Brownian bridge for any x satisfying ‖x‖∞ → 0 as n → ∞, where β = 1 for the real case and β = 2 for the complex case. Such a result indicates that the orthogonal (resp. unitary) matrices with columns being the eigenvectors of Wigner matrices are asymptotically Haar distributed on the orthogonal (resp. unitary) group from a certain perspective.
Effective heat conduction in dispersion of wires
Authors: Behrang A. , Grmela M. , Dubois C. , Turenne S. , Lafleur P. G. , Lebon G.
Published: February 2014

We derive a formula for the heat conductivity coefficient of dispersions of wires in a homogeneous matrix. Such formula is particularly useful for thermoelectric applications. The method used to derive this type of formula in Behrang et al. [J. Appl. Phys. 114, 014305 (2013)] for spherical particles is adapted to generally oriented wires of a finite length. Both diffuse and specular scatterings on the wire-matrix interface are considered. The results obtained previously from numerical solutions of the phonon kinetic equation under the assumption of diffuse scattering agree with predictions based on the formula.
A unified equation for predicting the dielectric constant of a two phase composite
Authors: He Hua , Xu Yebin
Published: February 2014

The dielectric properties of BaZr0.25Ti0.75O3/BaMg6Ti6O19 composites were investigated. A concise equation to predict the dielectric constant of the BaZr0.25Ti0.75O3/BaMg6Ti6O19 composites was derived. The validity and applicability of the equation were also validated via some experiments data, including ferroelectric-dielectric, dielectric-dielectric, polymer-ferroelectric, and polymer-dielectric composites from other literatures. The agreement between the dielectric constant calculated by the equation and the measured values was better than in any other case reported before.
Characterization of the quasi-one-dimensional compounds δ-(EDT-TTF-CONMe2)2X, X=AsF6 and Br by vibrational spectroscopy and density functional theory calculations
Authors: Peterseim Tobias , Antal Ágnes , Dressel Martin , Batail Patrick , Drichko Natalia
Published: February 2014

We have investigated the infrared spectra of the quarter-filled charge-ordered insulators δ-(EDT-TTF-CONMe2)2X (X= AsF6, Br) along all three crystallographic directions in the temperature range from 300 to 10 K. DFT-assisted normal mode analysis of the neutral and ionic EDT-TTF-CONMe2 molecule allows us to assign the experimentally observed intramolecular modes and to obtain relevant information on the charge ordering and intramolecular interactions. From frequencies of charge-sensitive vibrations we deduce that the charge-ordered state is already present at room temperature and does not change on cooling, in agreement with previous NMR measurements. The spectra taken along the stacking direction clearly show features of vibrational overtones excited due to the anharmonic electronic molecule potential caused by the large charge disproportionation between the molecular sites. The shift of certain vibrational modes indicates the onset of the structural transition below 200 K.
Flexible spintronic devices on Kapton
Authors: Bedoya-Pinto Amilcar , Donolato Marco , Gobbi Marco , Hueso Luis E. , Vavassori Paolo
Published: February 2014

Magnetic tunnel junctions and nano-sized domain-wall conduits have been fabricated on the flexible substrate Kapton. Despite the delicate nature of tunneling barriers and zig-zag shaped nanowires, the devices show an outstanding integrity and robustness upon mechanical bending. High values of bending angle (r = 5 mm) have been achieved without degradation of the device performance, reaching room-temperature tunneling magnetoresistance ratios of 12% in bended Co/Al2O3/NiFe junctions. In addition, a suitable route to pattern high-quality nanostructures directly on the polyimide surface is established. These results demonstrate that Kapton is a promising platform for low-cost, flexible spintronic applications involving tunnel junction elements and nanostructurization.
Native and induced triplet nitrogen-vacancy centers in nano- and micro-diamonds: Half-field electron paramagnetic resonance fingerprint
Authors: Shames A. I. , Osipov V. Yu. , von Bardeleben H.-J. , Boudou J.-P. , Treussart F. , Vul’ A. Ya.
Published: February 2014

Multiple frequency electron paramagnetic resonance (EPR) study of small (4–25 nm) nanodiamonds obtained by various dynamic synthesis techniques reveals systematic presence in the half-field (HF) region a distinctive doublet fingerprint consisting of resolved gHF1 = 4.26 and gHF2 = 4.00 signals. This feature is attributed to “forbidden” ΔMS = 2 transitions in EPR spectra of two native paramagnetic centers of triplet (S = 1) origin designated as TR1 and TR2, characterized by zero field splitting values D1 = 0.0950 ± 0.002 cm−1 and D2 = 0.030 ± 0.005 cm−1. Nanodiamonds of ∼50 nm particle size, obtained by crushing of Ib type nitrogen rich synthetic diamonds, show only HF TR2 signal whereas the same sample undergone high energy (20 MeV) electron irradiation and thermal annealing demonstrates rise of HF TR1 signal. The same HF TR1 signals appear in the process of fabrication of fluorescent nanodiamonds from micron-size synthetic diamond precursors. Results obtained allow unambiguous attribution of the half-field TR1 EPR signals with gHF1 = 4.26, observed in nano- and micron-diamond powders, to triplet negatively charged nitrogen-vacancy centers. These signals are proposed as reliable and convenient fingerprints in both qualitative and quantitative study of fluorescent nano- and micron-diamonds.
Exchange bias and blocking temperature distribution of Fe-film/CoO-nanoparticle hybrid bilayers
Authors: Zhang Wei , Krishnan Kannan M.
Published: February 2014

We fabricated and characterized Fe-film/CoO-nanoparticle hybrid bilayers and studied their temperature-dependent magnetic properties. The magnetic nanoparticles are uncoupled or weakly coupled in the particle films, which essentially resemble the antiferromagnetic grains in the deposited thin films. The size and size distribution of the nanoparticles can be well-controlled by chemical synthesis prior to assembling, providing additional route for engineering the antiferromagnetic layer in exchange-bias systems. Using cycled annealing-cooling measurements, we observed a unimodal blocking-temperature distribution in our samples that is a reflection of the intrinsic antiferromagnetic monodisperse “grain” size distribution. The absence of the low-temperature contribution is likely attributed to both the fabrication process and the nanoparticle morphology.
Optical absorption in InP/InGaAs/InP double-heterostructure nanopillar arrays for solar cells
Authors: Zhang Xu , Sun Xiao-Hong , Huang Hui , Wang Xishi , Huang Yongqing , Ren Xiaomin
Published: February 2014

The light trapping properties of InP/InGaAs/InP double-heterostructure nanopillar arrays (DH-NPAs) solar cells have been theoretically investigated. The influence of the geometric parameters on the optical absorption of DH-NPAs has been thoroughly analyzed by using rigorous coupled wave analysis algorithm and finite element method. The optical absorption enhancement of DH-NPAs as compared to InP/InGaAs/InP double-heterostructure nanowire arrays (DH-NWAs) in the whole wavelength regime has been demonstrated. The short-circuit current of DH-NPAs with the optimized design can achieve 61.3 mA/cm2, which is 15% higher than that of DH-NWAs with the same geometric configurations, and three times higher than that of thin-film layer with the same thickness. Meanwhile, the absorption profiles at different wavelength and angle-dependant optical properties of DH-NPAs are also evaluated.
Connection stiffness and dynamical docking process of flux pinned spacecraft modules
Authors: Lu Yong , Zhang Mingliang , Gao Dong
Published: February 2014

This paper describes a novel kind of potential flux pinned docking system that consists of guidance navigation and control system, the traditional extrusion type propulsion system, and a flux pinned docking interface. Because of characteristics of passive stability of flux pinning, the docking control strategy of flux pinned docking system only needs a series of sequential control rather than necessary active feedback control, as well as avoidance of hazardous collision accident. The flux pinned force between YBaCuO (YBCO) high temperature superconductor bulk and permanent magnet is able to be given vent based on the identical current loop model and improved image dipole model, which can be validated experimentally. Thus, the connection stiffness between two flux pinned spacecraft modules can be calculated based on Hooke's law. This connection stiffness matrix at the equilibrium position has the positive definite performance, which can validate the passively stable connection of two flux pinned spacecraft modules theoretically. Furthermore, the relative orbital dynamical equation of two flux pinned spacecraft modules can be established based on Clohessy-Wiltshire's equations and improved image dipole model. The dynamical docking process between two flux pinned spacecraft modules can be obtained by way of numerical simulation, which suggests the feasibility of flux pinned docking system.
Bi2O3 liquid phase assisted and Mn substituted permeability and magnetic properties of Ni-Cu-Zn ferrite for multilayer chip inductor application
Authors: Shirsath Sagar E. , Yasukawa Yukiko , Ghasemi Ali , Liu Xiaoxi , Morisako Akimitsu
Published: February 2014

In the present work, low-temperature fired MnxNi0.5−xCu0.25Zn0.25Fe2O4 + Bi2O3 (x = 0.0 to 0.45) was synthesized by the sol-gel auto combustion technique at a temperature of 1073 K. Bi2O3 (with 2 wt. %) was used as a sintering aid for improving the density, microstructure and lowering the sintering temperature of Mn-Ni-Cu-Zn ferrites. Synthesized samples were investigated for their structural, magnetic, and electrical properties such as density, porosity, saturation magnetization, and permeability as a function of Mn2+ substitution. Permeability and saturation magnetization were found to increase with the replacement of Ni2+ with Mn2+. Bulk density of 4.5 g/cm3 was observed for Mn-Ni-Cu-Zn ferrite with Bi2O3 additives which is greater than that of pure Mn-Ni-Cu-Zn ferrite (4.1 g/cm3). Saturation magnetization of NiCuZn ferrite increased from 37 to 63 emu/g with increase in Mn2+ substitution. Mn substituted NiCuZn ferrite shows higher complex permeability (μ′ = 672) than that of the pure NiCuZn ferrite (μ′ = 433). Curie temperature determined from temperature dependent permeability data shows that Tc attains maximum value of 707 K.
Supercontinuum generation and lasing in thulium doped tellurite microstructured fibers
Authors: Jia Zhi-Xu , Liu Lai , Yao Chuan-Fei , Qin Guan-Shi , Ohishi Yasutake , Qin Wei-Ping
Published: February 2014

We report supercontinuum (SC) generation in Tm3+ doped tellurite microstructured fibers (TMFs) pumped by a 1.56 μm femtosecond fiber laser. In comparison with SC generation in undoped TMFs, the SC spectral bandwidth and the spectral intensity in the wavelength region of >1.9 μm are evidently enlarged in Tm3+ doped TMFs owing to the contribution of the combination of linear gain of Tm3+ and the nonlinear optical effects to spectral broadening. Furthermore, a transition from SC generation to 1.887 μm lasing (Tm3+: 3F4→3H6 transition) is observed in Tm3+ doped TMFs by varying the pulse width of the pump laser from 0.29 to 3.47 ps, which gives the evidence of the above spectral broadening mechanism. This is the first observation of the transition from SC generation to lasing, to the best of our knowledge.
Spectral response of a droplet in pulsating external flow field
Authors: Deepu P. , Basu Saptarshi
Published: February 2014

A droplet introduced in an external convective flow field exhibits significant multimodal shape oscillations depending upon the intensity of the aerodynamic forcing. In this paper, a theoretical model describing the temporal evolution of normal modes of the droplet shape is developed. The fluid is assumed to be weakly viscous and Newtonian. The convective flow velocity, which is assumed to be incompressible and inviscid, is incorporated in the model through the normal stress condition at the droplet surface and the equation of motion governing the dynamics of each mode is derived. The coupling between the external flow and the droplet is approximated to be a one-way process, i.e., the external flow perturbations effect the droplet shape oscillations and the droplet oscillation itself does not influence the external flow characteristics. The shape oscillations of the droplet with different fluid properties under different unsteady flow fields were simulated. For a pulsatile external flow, the frequency spectra of the normal modes of the droplet revealed a dominant response at the resonant frequency, in addition to the driving frequency and the corresponding harmonics. At driving frequencies sufficiently different from the resonant frequency of the prolate-oblate oscillation mode of the droplet, the oscillations are stable. But at resonance the oscillation amplitude grows in time leading to breakup depending upon the fluid viscosity. A line vortex advecting past the droplet, simulated as an isotropic jump in the far field velocity, leads to the resonant excitation of the droplet shape modes if and only if the time taken by the vortex to cross the droplet is less than the resonant period of the P2 mode of the droplet. A train of two vortices interacting with the droplet is also analysed. It shows clearly that the time instant of introduction of the second vortex with respect to the droplet shape oscillation cycle is crucial in determining the amplitude of oscillation.
Voltage-induced reversible changes in the magnetic coercivity of Fe/ZnO heterostructures
Authors: Lin Wen-Chin , Chang Po-Chun , Tsai Cheng-Jui , Shieh Tsung-Chun , Lo Fang-Yuh
Published: February 2014

In this study, the magnetic coercivity (Hc) of Fe/ZnO heterostructure monotonically decreased as voltage was applied. The reversibility of this effect was demonstrated by cyclically changing the bias voltage from 0 to 6–9 V; the Hc decreased 15%–20%. The Hc value exhibited the same variation whether the applied voltage was positive or negative. As thick Fe-oxide gradually formed at the interface by using direct current heating, the Hc increased and the Fe/ZnO heterostructure demonstrated a similar voltage-induced reduction of Hc.
Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates
Authors: Bregolin F. L. , Krockert K. , Prucnal S. , Vines L. , Hübner R. , Svensson B. G. , Wiesenhütter K. , Möller H.-J. , Skorupa W.
Published: February 2014

Higher conversion efficiencies while reducing costs at the same time is the ultimate goal driving the advancement of solar cell development. In this work, solar cell emitters are formed in Si substrates by plasma immersion ion implantation (PIII) of phosphine and posterior millisecond-range flash lamp annealing (FLA). In Si-based solar cells, hydrogen plays a fundamental role due to its excellent passivation properties. The optical and electrical properties of the fabricated emitters will be studied, with particular interest in their dependence on the hydrogen content present in the samples. The influence of different FLA annealing parameters and a comparison with traditional thermal treatments such as rapid thermal annealing (RTA) and furnace annealing (FA) will be presented. The samples treated by FLA at 1200 °C for 20 ms in forming gas show sheet resistance values of the order of 60 Ω/◻, and minority carrier diffusion lengths in the range of ∼200 μm without the use of a capping layer for surface passivation. Those results are significantly better than the ones observed from RTA or FA annealed samples. The simultaneous implantation of hydrogen during the doping process, combined with optimal FLA annealing parameters, gave promising results for the application of this technology in replacing the conventional POCl3 deposition and diffusion.
Micro-coil detection of nuclear magnetic resonance for nanofluidic samples
Authors: Shibahara A. , Casey A. , Lusher C. P. , Saunders J. , Aßmann C. , Schurig Th. , Drung D.
Published: February 2014

We have developed a novel dc SQUID system with a micro-coil input circuit to act as a local probe of quantum matter and nanosystems. The planar niobium micro-coil pickup loop is located remotely from the SQUID, coupled through a superconducting twisted pair. A high degree of coupling between the coil and the region of interest of similar dimensions (up to ∼ 100 microns) can be achieved. We report nuclear magnetic resonance (NMR) measurements to characterise the sensitivity of these coils to 3He in the gas phase at 4.2 K in a 30 mT magnetic field.
Gendering Fashion, Fashioning Fur: On the (re)production of a Gendered Labor Market within a Craft Industry in Transition
Authors: Rantisi Norma M
Published: February 2014

What are the implications of the new economy for gender equality in labor markets? Does an economy that privileges ‘immaterial’ labor (the production of ideas) over ‘material’ labor (the manual production of goods) signal the possibility for greater labor market inclusion? Building on critical accounts of the new economy, I examine the bases for continued gender hierarchies through an analysis of the contemporary restructuring of the fur industry in Canada. As a traditional craft industry, fur has sought to adapt to new-economy imperatives by incorporating ‘immaterial’ labor in the form of fashion design. However, these efforts have been limited, as the (predominantly male) fur manufacturers have sought to retain authority in a changing economy by integrating design as a subordinate activity—a subordination made possible through a coding of design as feminine and through the deployment of the fashion designer as a flexible source of labor. Drawing on interviews with manufacturers, designers, and other industry actors, I analyze how new-economy imperatives intersect with local institutional practices and ideologies to reproduce a gendered labor market.
Looking at a Blurry Old Family Photo? Zoom Out!
Authors: Shahangian Kimeya , Oruc Ipek
Published: February 2014

We investigated recognition of blurry faces and whether viewing size affects identification of such severely degraded images. Despite the common belief that face perception relies on middle spatial frequencies, the critical spatial frequency band for face recognition is not fixed but rather depends on size. This is especially pronounced at small sizes, where observers choose to utilize lower, rather than middle, frequencies to identify a face. Here we assessed recognition of identity via a novel use of the face adaptation paradigm. We examined face identity aftereffects of blurry and intact adaptors at two sizes. Intact adaptors induced significant aftereffects regardless of size. Small, but not large, blurry adaptors produced aftereffects despite the fact that both contained exactly the same level of facial detail. This suggests an inability to utilize low-frequency information for perceiving identity in large faces. We conclude that (1) size is a key factor in human face recognition processes and (2) coarse facial images are better recognized at small sizes.