bluuebunny/crossref_metadata_2025 huggingface dataset:
Density functional theory study on organically surface-modified silicene
Authors: Wang Rong , Pi Xiaodong , Ni Zhenyi , Liu Yong , Yang Deren
Published: April 2015

The geometrical structures, band structures and optical absorption of organically surface-modified silicene have been investigated by density functional theory.
Three-phase junction for modulating electron–hole migration in anatase–rutile photocatalysts
Authors: Zhao Wei-Na , Zhu Sheng-Cai , Li Ye-Fei , Liu Zhi-Pan
Published: April 2015

Theory resolves the anatase–rutile phase junction structure and characterizes its role in photocatalysis as a single-way valve modulating electron–hole separation.
A facile synthesis of mesoporous Co3O4/CeO2 hybrid nanowire arrays for high performance supercapacitors
Authors: Cui Jiewu , Zhang Xinyi , Tong Liang , Luo Jinbao , Wang Yan , Zhang Yong , Xie Kui , Wu Yucheng
Published: April 2015

Mesoporous Co3O4/CeO2 hybrid nanowire arrays are synthesized and employed as electrode materials for supercapacitors. These nanomaterials exhibit remarkable pseudocapacitance and superior cycling stability.
Integrating theory, synthesis, spectroscopy and device efficiency to design and characterize donor materials for organic photovoltaics: a case study including 12 donors
Authors: Oosterhout S. D. , Kopidakis N. , Owczarczyk Z. R. , Braunecker W. A. , Larsen R. E. , Ratcliff E. L. , Olson D. C.
Published: April 2015

Calculations predict energy levels of polymers for OPV, and time-resolved microwave conductivity pre-screens for charge generation ability prior to device fabrication.
pH-responsive octylamine coupling modification of carboxylated aluminium oxide surfaces
Authors: Alexander Shirin , Morrow Lauren , Lord Alex M. , Dunnill Charles W. , Barron Andrew R.
Published: April 2015

Formation of a pH-sensitive coupling layer through both physisorption and chemisorption is reported.
Synthesis of mesoporous carbon–silica nanocomposite water-treatment membranes using a triconstituent co-assembly method
Authors: Chua Yen T. , Lin Chun Xiang C. , Kleitz Freddy , Smart Simon
Published: April 2015

Mesoporous carbon–silica nanocomposite membranes with varying silica content demonstrate excellent performance in vacuum membrane distillation (VMD)-based desalination.
A polyimide based all-organic sodium ion battery
Authors: Banda Harish , Damien Dijo , Nagarajan Kalaivanan , Hariharan Mahesh , Shaijumon Manikoth M.
Published: April 2015

N,N′-diamino-3,4,9,10-perylenetetracarboxylic polyimide (PI) based materials show excellent electrochemical performance as cathodes for sodium-ion batteries and an all-organic sodium ion battery using this polyimide as the cathode and disodium terephthalate (NaTP) (pre-sodiated) as the anode is demonstrated.
Development of phenylboronic acid-functionalized nanoparticles for emodin delivery
Authors: Wang Bo , Chen Limin , Sun Yingjuan , Zhu Youliang , Sun Zhaoyan , An Tiezhu , Li Yuhua , Lin Yuan , Fan Daping , Wang Qian
Published: April 2015

The uniform PBA-functionalized nanoparticles were fabricated using the PBA homopolymer via the solvent displacement method. PBA-NPs can be used as a carrier to load polyphenolic drugs.
A primary study of poly(propylene fumarate)–2-hydroxyethyl methacrylate copolymer scaffolds for tarsal plate repair and reconstruction in rabbit eyelids
Authors: Gao Qi , Hu Bin , Ning Qingyao , Ye Chen , Xie Jiajun , Ye Juan , Gao Changyou
Published: April 2015

A poly(propylene fumarate)-co-2-hydroxyethyl methacrylate (PPF–HEMA) copolymer scaffold was designed for tarsal plate repair and reconstruction in rabbit eyelids.
Pluripotency maintenance of amniotic fluid-derived stem cells cultured on biomaterials
Authors: Wang Pin-Yu , Lee Henry Hsin-chung , Higuchi Akon , Ling Qing-Dong , Lin Hong-Ren , Li Hsin-Fen , Suresh Kumar S. , Chang Yung , Alarfaj Abdullah A. , Munusamy Murugan A. , Chen Da-Chung , Hsu Shih-Tien , Wang Han-Chow , Hsiao Hung-Yi , Wu Gwo-Jang
Published: April 2015

Human amniotic fluid-derived stem cells can maintain their pluripotency when cultured on soft hydrogels.
Organic optoelectronic interfaces with anomalous transient photocurrent
Authors: Hu Laigui , Liu Xian , Dalgleish Simon , Matsushita Michio M. , Yoshikawa Hirofumi , Awaga Kunio
Published: April 2015

In this review, anomalous transient photocurrent from organic semiconductor devices in response to square-wave light pulses in the literature are discussed; current efforts to utilize these transients are highlighted, such as in transient-type photodetectors and artificial retinas.
Piezoelectric properties of individual nanocrystallites of Ba0.85Ca0.15Zr0.1Ti0.9O3 obtained by oxalate precursor route
Authors: Bharathi P. , Thomas P. , Varma K. B. R.
Published: April 2015

Ferroelectric domain pattern and piezoresponse (d33) versus DC bias voltage for the BCZT nanocrystalline powder.
Studies on bifunctional Fe(ii)-triazole spin crossover nanoparticles: time-dependent luminescence, surface grafting and the effect of a silica shell and hydrostatic pressure on the magnetic properties
Authors: Herrera Juan Manuel , Titos-Padilla Silvia , Pope Simon J. A. , Berlanga Isadora , Zamora Félix , Delgado Juan José , Kamenev Konstantin V. , Wang Xiao , Prescimone Alessandro , Brechin Euan K. , Colacio Enrique
Published: April 2015

SiO2-coated Fe-triazole spin-crossover nanoparticles were functionalized with dansyl luminophores.
Global shutter‐mesh architecture with surround‐boosted driving scheme for time‐of‐flight depth sensors
Authors: Choi Jaehyuk , Shin Jungsoon , Kang Byongmin
Published: April 2015

Presented is an architecture with mesh‐structured electronic shutters and surround shutter drivers with positive/negative boosting to enhance the depth accuracy in three‐dimensional (3D) depth sensors with a time‐of‐flight (TOF) measurement scheme. High‐frequency modulation in the TOF scheme degrades the charge‐transfer efficiency in high‐resolution sensors because of the large parasitic resistance and the capacitance of the electronic shutters and shutter lines. This degradation suppresses modulation contrast, which induces depth errors. The global shutter‐mesh architecture and surround‐boosted driving scheme is implemented for high‐modulation contrast in large‐format depth sensors with a 1280 × 960 resolution.
HMSIW bandstop filter loaded with half complementary split‐ring resonator
Authors: Cai Yang , Qian Zuping , Cao Wenquan , Zhang Yingsong , Yang Liu
Published: April 2015

A novel half‐mode substrate‐integrated waveguide (HMSIW) bandstop filter loaded with a half complementary split‐ring resonator (HCSRR) is investigated. The experiment indicates that the novel HCSRR shows almost the same resonant characteristic but half size in contrast with the original CSRR. Then the proposed HCSRR is etched on the middle of the HMSIW and a compact bandstop filter is realised. A practical example for a HMSIW bandstop filter is fabricated and measured. The measured results show good agreement with the simulated ones.
Sparse DNN‐based speaker segmentation using side information
Authors: Ma Yong , Bao Chang‐Chun
Published: April 2015

Sparse deep neural networks (SDNNs) for speaker segmentation are proposed. First, the SDNNs are trained using the side information that is the class label of the input. Then, speaker‐specific features are extracted from the super‐vector feature of the speech signal by the SDNNs. Lastly, the label of each speech frame is obtained by K‐means clustering, which is used to segment different speakers of a continuous speech stream. The performance evaluation using the multi‐speaker speech stream corpus generated from the TIMIT database shows that the proposed speaker segmentation algorithm outperforms the Bayesian information criterion method and the deep auto‐encoder networks method.
Dynamic performance of doubly‐fed induction generator stator flux during consecutive grid voltage variations
Authors: Zhu Rongwu , Chen Zhe , Wu Xiaojie
Published: April 2015

For the grid‐connected doubly‐fed induction generator (DFIG)‐based wind turbine, because of the stator connected to the grid directly, the stator flux easily suffers from the effects of grid voltage variations, such as grid disturbances and grid faults. Moreover, since the magnetic field is excited by the rotor current, stator flux is also affected by the rotor current. Therefore this study systematically studies the dynamic performances of stator flux under consecutive grid voltage variations and varying rotor currents, and its influence on the performances of the DFIG during grid faults. The analyses reveal that the stator flux can be accumulated by the consecutive variations of the stator voltage, and the instants of grid voltage variations can lead to different amplitudes of the stator flux. In addition, the conventional vector control strategy and the active damping strategy are compared with the behaviour of the stator flux. Furthermore, the simulation and experiment are carried out to validate the theoretical analyses, and the results have clearly confirmed the correctness and effectiveness of the analyses of the stator flux performances.
Reversible switching of ferromagnetism in ZnCuO nanorods by electric field
Authors: Zou Changwei , Wang Hongjun , Liang Feng , Shao Lexi
Published: April 2015

The reproducible switching of ferromagnetism in ZnCuO nanorods by applying a reversible electric field has been realized. High-resolution transmission electron microscopy images showed a hexagonal wurtzite structure with no detectable trace of secondary phase or precipitation of Cu impurity in the ZnCuO nanorods. The Cu concentrations in the ZnCuO nanorods were tested by energy dispersive spectroscopy and x-ray photoelectron spectroscopy and found to be about 2.7 at. %. The switching mechanism is confirmed in terms of the formation and rupture of conductive filaments, with oxygen vacancies (VO) localized mainly on surface of the ZnCuO nanorods. Subsequently, the variation of VO concentration during the resistive switching process modulates the ferromagnetism of the ZnCuO nanorods. The saturation magnetization at low resistance state is apparently 6.4 times larger than that at high resistance state for an Au/ZnCuO/ITO structure. An indirect double-exchange model has been used to explain the ferromagnetism in ZnCuO nanorods.
The impact of the competitive adsorption of ions at surface sites on surface free energies and surface forces
Authors: Parsons Drew F. , Salis Andrea
Published: April 2015

The relationship between surface charge and surface potential at the solid-liquid interface is often determined by a charge regulation process, the chemisorption of a potential determining ion such as H+. A subtle ion-specific effect can be observed when other ions compete with the primary potential determining ion to bind to a surface site. Site competition may involve alternative ions competing for a first binding site, e.g., metals ions competing with H+ to bind to a negatively charged oxide or carboxyl site. Second-binding sites with site competition may also be found, including amphoteric OH2+ sites, or anion binding to amine groups. In this work, a general theoretical model is developed to describe the competitive adsorption of ions at surface sites. Applied to the calculation of forces, the theory predicts a 20% increase in repulsion between titania surfaces in 1 mM NaCl, and a 25% reduction in repulsion between silica surfaces in 0.1M NaCl compared to calculations neglecting ion site competition.
Obtaining the Hessian from the force covariance matrix: Application to crystalline explosives PETN and RDX
Authors: Pereverzev Andrey , Sewell Thomas D.
Published: April 2015

We show that for solids the effective Hessian matrix, averaged over the canonical ensemble, can be calculated from the force covariance matrix. This effective Hessian reduces to the standard Hessian as the temperature approaches zero, while at finite temperatures it implicitly includes anharmonic corrections. As a case study, we calculate the effective Hessians and the corresponding normal mode eigenvectors and frequencies for the crystalline organic explosives pentaerythritol tetranitrate and α-1,3,5-trinitro-1,3,5-triazacyclohexane. The resulting normal mode frequencies are compared to those obtained by diagonalizing the standard Hessian matrix of second derivatives in Cartesian displacements about the potential energy minimum. Effects of temperature and statistical noise on the effective Hessians and normal mode frequencies are discussed.
Solvation of fluoro-acetonitrile in water by 2D-IR spectroscopy: A combined experimental-computational study
Authors: Cazade Pierre-André , Tran Halina , Bereau Tristan , Das Akshaya K. , Kläsi Felix , Hamm Peter , Meuwly Markus
Published: April 2015

The solvent dynamics around fluorinated acetonitrile is characterized by 2-dimensional infrared spectroscopy and atomistic simulations. The lineshape of the linear infrared spectrum is better captured by semiempirical (density functional tight binding) mixed quantum mechanical/molecular mechanics simulations, whereas force field simulations with multipolar interactions yield lineshapes that are significantly too narrow. For the solvent dynamics, a relatively slow time scale of 2 ps is found from the experiments and supported by the mixed quantum mechanical/molecular mechanics simulations. With multipolar force fields fitted to the available thermodynamical data, the time scale is considerably faster—on the 0.5 ps time scale. The simulations provide evidence for a well established CF–HOH hydrogen bond (population of 25%) which is found from the radial distribution function g(r) from both, force field and quantum mechanics/molecular mechanics simulations.
Semiclassical Wigner theory of photodissociation in three dimensions: Shedding light on its basis
Authors: Arbelo-González W. , Bonnet L. , García-Vela A.
Published: April 2015

The semiclassical Wigner theory (SCWT) of photodissociation dynamics, initially proposed by Brown and Heller [J. Chem. Phys. 75, 186 (1981)] in order to describe state distributions in the products of direct collinear photodissociations, was recently extended to realistic three-dimensional triatomic processes of the same type [Arbelo-González et al., Phys. Chem. Chem. Phys. 15, 9994 (2013)]. The resulting approach, which takes into account rotational motions in addition to vibrational and translational ones, was applied to a triatomic-like model of methyl iodide photodissociation and its predictions were found to be in nearly quantitative agreement with rigorous quantum results, but at a much lower computational cost, making thereby SCWT a potential tool for the study of polyatomic reaction dynamics. Here, we analyse the main reasons for this agreement by means of an elementary model of fragmentation explicitly dealing with the rotational motion only. We show that our formulation of SCWT makes it a semiclassical approximation to an approximate planar quantum treatment of the dynamics, both of sufficient quality for the whole treatment to be satisfying.
Coupling between hydrodynamics, acoustics, and heat release in a self-excited unstable combustor
Authors: Harvazinski Matthew E. , Huang Cheng , Sankaran Venkateswaran , Feldman Thomas W. , Anderson William E. , Merkle Charles L. , Talley Douglas G.
Published: April 2015

The unsteady gas dynamic field in a closed combustor is determined by the nonlinear interactions between chamber acoustics, hydrodynamics, and turbulent combustion that can energize these modes. These interactions are studied in detail using hybrid RANS/large eddy simulations (RANS = Reynolds Averaged Navier-Stokes) of a non-premixed, high-pressure laboratory combustor that produces self-excited longitudinal instabilities. The main variable in the study is the relative acoustic length between the combustion chamber and the tube that injects oxidizer into the combustor. Assuming a half-wave (closed-closed) combustion chamber, the tube lengths approximately correspond to quarter-, 3/8-, and half-wave resonators that serve to vary the phasing between the acoustic modes in the tube and the combustion chamber. The simulation correctly predicts the relatively stable behavior measured with the shortest tube and the very unstable behavior measured with the intermediate tube. Unstable behavior is also predicted for the longest tube, a case for which bifurcated stability behavior was measured in the experiment. In the first (stable) configuration, fuel flows into the combustor uninterrupted, and heat release is spatially continuous with a flame that remains attached to the back step. In the second (unstable) configuration, a cyclic process is apparent comprising a disruption in the fuel flow, subsequent detachment of the flame from the back step, and accumulation of fuel in the recirculation zone that ignites upon arrival of a compression wave reflected from the downstream boundary of the combustion chamber. The third case (mixed stable/unstable) shares features with both of the other cases. The major difference between the two cases predicted to be unstable is that, in the intermediate length tube, a pressure wave reflection inside the tube pushes unburnt fuel behind the back step radially outward, leading to a post-coupled reignition mechanism, while in the case of the longest tube, the reignition is promoted by vortex convection and combustor-wall interaction. Other flow details indicated by the simulation include the relative phase between flow resonances in the tube and the combustor, increased mixing due to baroclinic torque, and the presence of an unsteady triple flame.
Research of 100 MHz ultra-low-jitter clock generating circuit
Authors: Qiu Duyu , Tan Feng , Tian Shulin , Zeng Hao , Ye Peng
Published: April 2015

Jitter which quantifies the quality of a clock is an important specification. It is of great significance for an electronic system. To obtain a good signal-to-noise ratio for sampling systems, there must be clocks with low jitter performances. By using the relationship between jitter and phase noise, the 100 MHz clock generating circuit with ultra-low jitter and phase noise characteristics are studied in this paper. Bipolar junction transistor with low noise figure and low corner frequency should be selected. Inductance and capacitance in the feedback circuit are obviously the main contributions to the jitter. Impacts of the loaded quality factor (QL) of the circuit on the jitter are analyzed, and the explicit expression for the jitter based on circuit components is derived as well. The simulation and experiment results are proved to show that the jitter and phase noise characteristics can be improved by increasing QL of the circuit.
Particle trapping: A key requisite of structure formation and stability of Vlasov–Poisson plasmas
Authors: Schamel Hans
Published: April 2015

Particle trapping is shown to control the existence of undamped coherent structures in Vlasov–Poisson plasmas and thereby affects the onset of plasma instability beyond the realm of linear Landau theory.
On non-autonomous dynamical systems
Authors: Anzaldo-Meneses A.
Published: April 2015

In usual realistic classical dynamical systems, the Hamiltonian depends explicitly on time. In this work, a class of classical systems with time dependent nonlinear Hamiltonians is analyzed. This type of problems allows to find invariants by a family of Veronese maps. The motivation to develop this method results from the observation that the Poisson-Lie algebra of monomials in the coordinates and momenta is clearly defined in terms of its brackets and leads naturally to an infinite linear set of differential equations, under certain circumstances. To perform explicit analytic and numerical calculations, two examples are presented to estimate the trajectories, the first given by a nonlinear problem and the second by a quadratic Hamiltonian with three time dependent parameters. In the nonlinear problem, the Veronese approach using jets is shown to be equivalent to a direct procedure using elliptic functions identities, and linear invariants are constructed. For the second example, linear and quadratic invariants as well as stability conditions are given. Explicit solutions are also obtained for stepwise constant forces. For the quadratic Hamiltonian, an appropriated set of coordinates relates the geometric setting to that of the three dimensional manifold of central conic sections. It is shown further that the quantum mechanical problem of scattering in a superlattice leads to mathematically equivalent equations for the wave function, if the classical time is replaced by the space coordinate along a superlattice. The mathematical method used to compute the trajectories for stepwise constant parameters can be applied to both problems. It is the standard method in quantum scattering calculations, as known for locally periodic systems including a space dependent effective mass.
Ultrafast 2D-IR spectroelectrochemistry of flavin mononucleotide
Authors: El Khoury Youssef , Van Wilderen Luuk J. G. W. , Bredenbeck Jens
Published: April 2015

We demonstrate the coupling of ultrafast two-dimensional infrared (2D-IR) spectroscopy to electrochemistry in solution and apply it to flavin mononucleotide, an important cofactor of redox proteins. For this purpose, we designed a spectroelectrochemical cell optimized for 2D-IR measurements in reflection and measured the time-dependent 2D-IR spectra of the oxidized and reduced forms of flavin mononucleotide. The data show anharmonic coupling and vibrational energy transfer between different vibrational modes in the two redox species. Such information is inaccessible with redox-controlled steady-state FTIR spectroscopy. The wide range of applications offered by 2D-IR spectroscopy, such as sub-picosecond structure determination, IR band assignment via energy transfer, disentangling reaction mixtures through band connectivity in the 2D spectra, and the measurement of solvation dynamics and chemical exchange can now be explored under controlled redox potential. The development of this technique furthermore opens new horizons for studying the dynamics of redox proteins.
Evolution of fcc Cu clusters and their structure changes in the soft magnetic Fe85.2Si1B9P4Cu0.8 (NANOMET) and FINEMET alloys observed by X-ray absorption fine structure
Authors: Matsuura M. , Nishijima M. , Takenaka K. , Takeuchi A. , Ofuchi H. , Makino A.
Published: April 2015

It is known that Cu plays an essential role in reducing the grain size of precipitated bcc Fe(Si) nanocrystallites in a nanocrystalline soft-magnetic Fe85.2Si1B9P4Cu0.8 (NANOMET®) alloys like as an Fe73.5Si13.5B9Nb3Cu1 (FINEMET®). However, significant differences are there between two alloys; NANOMET has much higher iron content (∼85%) than FINEMET (73.5%) and the former contains P instead of Nb for the latter. In the present work, the local structure around Cu in FINEMET was measured by X-ray absorption fine structure (XAFS) at 20 K and compared with those of NANOMET during nanocrystallization. Definite differences between NANOMET and FINEMET are found in the way of the evolution of Cu clusters during nanocrystallization. In FINEMET, an fcc structure of Cu is recognized in an as-quenched ribbon indicating existence of a small number of Cu clusters or a very small size of Cu clusters which is stable up to 450 °C, while the fcc Cu clusters are developed rapidly above 450 °C. An fcc structure of the Cu clusters in FINEMET is retained all the way to the end of the nanocrystallization. On the contrary, for NANOMET the local structure around Cu changes in a sequence as “amorphous → fcc → bcc → fcc” by annealing. The reasons of such different behaviors of the local structure around Cu during nanocrystallization are discussed in terms of different contributions of Cu clusters in bcc Fe precipitation between FINEMET and NANOMET. A significantly fast crystallization process with an extraordinary large heat release can be another reason for the transition of the local structure around Cu from fcc to bcc for NANOMET.
Control of Brillouin short-pulse seed amplification by chirping the pump pulse
Authors: Lehmann G. , Spatschek K. H.
Published: April 2015

Seed amplification via Brillouin backscattering of a long pump pulse is considered. Similar to Raman amplification, several obstructive effects may occur during short-pulse Brillouin amplification. One is the spontaneous Raman backscattering of the pump before interacting with the seed. Preforming the plasma and/or chirping the pump will reduce unwanted pump backscattering. Optimized regions for low-loss pump propagation were proposed already in conjunction with Raman seed amplification. Hence, the influence of the chirp of the pump during Brillouin interaction with the seed becomes important and will be considered here. Both, the linear as well as the nonlinear evolution phases of the seed caused by Brillouin amplification under the action of a chirped pump are investigated. The amplification rate as well as the seed profiles are presented as function of the chirping rate. Also the dependence of superradiant scaling rates on the chirp parameter is discussed.
Systematic investigation of effects of exciton–acoustic-phonon scattering on photoluminescence rise times of free excitons in GaAs/Al0.3Ga0.7As single quantum wells
Authors: Nakayama Masaaki , Ohno Tatsuya , Furukawa Yoshiaki
Published: April 2015

We have systematically investigated the photoluminescence (PL) dynamics of free excitons in GaAs/Al0.3Ga0.7As single quantum wells, focusing on the energy relaxation process due to exciton–acoustic-phonon scattering under non-resonant and weak excitation conditions as a function of GaAs-layer thickness from 3.6 to 12.0 nm and temperature from 30 to 50 K. The free exciton characteristics were confirmed by observation that the PL decay time has a linear dependence with temperature. We found that the free exciton PL rise rate, which is the reciprocal of the rise time, is inversely linear with the GaAs-layer thickness and linear with temperature. This is consistent with a reported theoretical study of the exciton–acoustic-phonon scattering rate in the energy relaxation process in quantum wells. Consequently, it is conclusively verified that the PL rise rate is dominated by the exciton–acoustic-phonon scattering rate. In addition, from quantitative analysis of the GaAs-layer thickness and temperature dependences, we suggest that the PL rise rate reflects the number of exciton–acoustic-phonon scattering events.
Dark-field scattering spectroscopy to study transducer stability for heat-assisted magnetic recording
Authors: Cen Z. H. , Xu B. X. , Ji R. , Toh Y. T. , Yu Y. F.
Published: April 2015

Thermal stability of optical near field transducers is an important issue for heat-assisted magnetic recording (HAMR), which affects HAMR system lifetime. In this paper, dark-field scattering spectroscopy was used to study the stability of nanometer-scaled Au lollipop transducers that were subjected to thermal annealing. Variation in relative peak intensity and red-shifting in peak position can be observed in scattering spectra for transducer after annealing. Based on the optical characterizations on Au thin films and calculations of Mie scattering by finite-difference time domain simulations, the measured changes in transducer scattering properties can reflect annealing-induced variations in optical properties and dimensional feature size for the Au lollipop transducer. Dark-field scattering spectroscopy can be a promising method to examine HAMR near field transducer thermal stability.
Synthesis and magnetic properties of Ta/NdFeB-based composite microwires
Authors: Szary P. , Luciu I. , Duday D. , Périgo E. A. , Wirtz T. , Choquet P. , Michels A.
Published: April 2015

Magnetic NdFeB-based microwire composites have been prepared by the direct current magnetron sputtering technique in a specifically designed sputtering chamber for thin-film deposition in wire geometry. As substrate wire material, we have employed steel and Ta. Annealing of the substrate wires during the deposition process was performed by ohmic heating through the application of a direct current. Samples were characterized by means of vibrating sample magnetometry (VSM) and scanning electron microscopy. Best properties have been encountered when using Ta wires as core (substrate) material. The VSM data show a dramatic impact of the current applied during the deposition process on the magnetic properties. For higher current values, i.e., higher annealing temperatures, the wires exhibit a reversal process that is typical for a two-phase system. Moreover, an increase of the coercive field (and remanent magnetization) is observed, which is ascribed to a modification of the magnetic phase present in the sample due to the annealing. We find an indication for the formation of a magnetic easy-axis direction which is azimuthally oriented around the wire axis.
Effects of hydraulic pressure on cardiomyoblasts in a microfluidic device
Authors: Hsiao Yu-Fang , Pan Huei-Jyuan , Tung Yi-Chung , Chen Chien-Chang , Lee Chau-Hwang
Published: April 2015

We employed a microfluidic device to study the effects of hydraulic pressure on cardiomyoblast H9c2. The 170 mm Hg pressure increased the cellular area and the expression of atrial natriuretic peptide. With the same device, we demonstrated that the effects of hydraulic pressure on the cardiomyoblast could be reduced by the inhibitor of focal adhesion kinase. This mechanical–chemical antagonism could lead to a potential therapeutic strategy of hypertension-induced cardiac hypertrophy.
Electroluminescence from metal-oxide-semiconductor devices with erbium-doped CeO2 films on silicon
Authors: Lv Chunyan , Zhu Chen , Wang Canxing , Gao Yuhan , Ma Xiangyang , Yang Deren
Published: April 2015

We report on erbium (Er)-related electroluminescence (EL) in the visible and near-infrared (NIR) from metal-oxide-semiconductor (MOS) devices with Er-doped CeO2 (CeO2:Er) films on silicon. The onset voltage of such EL under either forward or reverse bias is smaller than 10 V. Moreover, the EL quenching can be avoidable for the CeO2:Er-based MOS devices. Analysis on the current-voltage characteristic of the device indicates that the electron transportation at the EL-enabling voltages under either forward or reverse bias is dominated by trap-assisted tunneling mechanism. Namely, electrons in n+-Si/ITO can tunnel into the conduction band of CeO2 host via defect states at sufficiently high forward/reverse bias voltages. Then, a fraction of such electrons are accelerated by electric field to become hot electrons, which impact-excite the Er3+ ions, thus leading to characteristic emissions. It is believed that this work has laid the foundation for developing viable silicon-based emitters using CeO2:Er films.
Effect of pressure on the structural properties of Li[Li0.1Ni0.35Mn0.55]O2
Authors: Zhang Yufeng , Wang Li , Yang Juping , He Xiangming , Wang Jixian , Zhang Yanli , Jin Yuhong , Li Yanchun , Xiong Lun
Published: April 2015

Li-rich cathode material Li[Li0.1Ni0.35Mn0.55]O2 was synthesized by a sol-gel method. The morphology and a-NaFeO2 type structure of the material at ambient conditions were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The high-pressure behavior of the material was studied at pressure up to 19.7 GPa by using angle dispersive synchrotron X-ray powder diffraction (ADXD). The studies affirmed that the a-NaFeO2 type structure existed up to at least 19.7 GPa. Rietveld refinement analysis indicated that the c/a lattice parameter ratio decreased and the Li-O bond length shrunk with the increasing pressure, however, the Li+/Ni2+ ions exchange increased under elevated pressure. The pressure-volume data of the material were fitted to the third-order Birch-Murnaghan equation of state and bulk modulus obtained upon compression from the fitting was 117 (1) GPa.
Ab initio study of radiation effects on the Li4Ti5O12 electrode used in lithium-ion batteries
Authors: Samin Adib , Kurth Michael , Cao Lei
Published: April 2015

Lithium-ion batteries are currently in wide use owing to their high energy density and enhanced capabilities. Li4Ti5O12 is a promising anode material for lithium-ion batteries because of its advantageous properties. Lithium-ion batteries could be exposed to radiation occurring in various conditions such as during outer space exploration and nuclear accidents. In this study, we apply density functional theory to explore the effect of radiation damage on this electrode and, ultimately, on the performance of the battery. It was found that radiation could affect the structural stability of the material. Furthermore, the electrode was shown to undergo a transition from insulator to metal, following the defects due to radiation. In addition, the effect of radiation on the intercalation potential was found to be highly dependent on the nature of the defect induced.
Growth and nickel uptake by serpentine and non-serpentine populations of Fimbristylis ovata (Cyperaceae) from Sri Lanka
Authors: Chathuranga P. K. D. , Dharmasena S. K. A. T. , Rajakaruna N. , Iqbal M. C. M.
Published: April 2015

Compared with serpentine floras of Southeast Asia, the serpentine vegetation of Sri Lanka is impoverished in regard to serpentine endemics and nickel hyperaccumulators. All species so far documented from the serpentine outcrops of Sri Lanka also have non-serpentine populations; it is unclear whether the serpentine populations are physiologically distinct and deserve ecotypic recognition. We conducted a preliminary study to examine whether serpentine and non-serpentine populations of Fimbristylis ovata represent locally adapted ecotypes by investigating their growth and potential for nickel uptake and tolerance under greenhouse conditions. Although both populations of F. ovata showed a similar growth pattern in serpentine soil during short-term exposure (21 days), the non-serpentine population was unable to survive in serpentine soil under long-term exposure (4 months). Both populations were able to uptake nickel from serpentine soil during short-term exposure (21 days). The serpentine population, however, translocated significantly more nickel from its roots to shoots (translocation factor 0.43) than the non-serpentine population (translocation factor 0.29). Our preliminary investigations suggest that the serpentine and non-serpentine populations of F. ovata may be locally adapted to their respective soils. However, additional studies are required to determine whether the populations deserve ecotypic recognition.
Importance of predation and viral lysis for bacterial mortality in a tropical western Indian coral-reef ecosystem (Toliara, Madagascar)
Authors: Bouvy M. , Got P. , Bettarel Y. , Bouvier T. , Carré C. , Roques C. , Rodier M. , Lope J. C. , Arfi R.
Published: April 2015

Size fractionation was performed using water from the Great Reef of Toliara (Madagascar) taken from two different habitats (ocean and lagoon) during the dry and wet seasons, to study the growth and mortality rates of bacterioplankton. Experiments were conducted with 1 and 100% of heterotrophic nanoflagellate (HNF) concentrations and virus-free water was obtained by tangential filtration (10kDa). During the dry season, in both environments, bacterial abundance and production were significantly lower than values recorded during the wet season. Bacterial growth rates without grazers were 0.88 day–1 in the lagoon and 0.58 day–1 in the ocean. However, growth rates were statistically higher without grazers and viruses (1.58 day–1 and 1.27 day–1). An estimate of virus-induced bacterial mortality revealed the important role played by viruses in the lagoon (0.70 day–1) and the ocean (0.69 day–1). During the wet season, bacterial growth rates without grazers were significantly higher in both environments than were values obtained in the dry season. However, the bacterial growth rates were paradoxally lower in the absence of viruses than with viruses in both environments. Our results suggest that changes in nutrient concentrations can play an important role in the balance between viral lysis and HNF grazing in the bacterial mortality. However, virus-mediated bacterial mortality is likely to act simultaneously with nanoflagellates pressure in their effects on bacterial communities.
Effects of gear type, entrance size and soak time on trap efficiency for freshwater crayfish Cherax destructor and C. albidus
Authors: Brown Paul , Hunt Taylor L. , Giri Khageswor
Published: April 2015

Freshwater crayfish support significant commercial and recreational fisheries worldwide. The genus Cherax is fished in Australia with a variety of fishing gears, yet little is known of the relative efficiency of the different fishing gears and methods. Additionally, freshwater-crayfish traps can pose a risk to air breathing by-catch such as aquatic mammals, reptiles and birds, so by-catch mitigation is important. We sought to understand whether freshwater-crayfish fishing can be undertaken efficiently, using passive traps and nets, without undue risk to air-breathing by-catch species. In field-experiments, we compared the efficiency of six gear types and tested the effect of five exclusion rings on catch performance over three soak times. The efficiency of gear types varied significantly by soak times. In productive locations, catch can be maximised by repeatedly deploying open-topped gear for short soak times. Opera-house traps fitted with fixed entrance rings (45–85-mm diameter) were not size-selective for yabbies. Encouragingly, open-topped gear and opera-house traps fitted with fixed ring entrances much smaller than many commercially available (45-mm diameter) still fish effectively for yabbies. We believe that smaller fixed ring-entrance size is likely to be correlated with a reduced risk of by-catch for air-breathing fauna.
Parametric uncertainty quantification in the Rothermel model with randomised quasi-Monte Carlo methods
Authors: Liu Yaning , Jimenez Edwin , Hussaini M. Yousuff , Ökten Giray , Goodrick Scott
Published: April 2015

Rothermel's wildland surface fire model is a popular model used in wildland fire management. The original model has a large number of parameters, making uncertainty quantification challenging. In this paper, we use variance-based global sensitivity analysis to reduce the number of model parameters, and apply randomised quasi-Monte Carlo methods to quantify parametric uncertainties for the reduced model. The Monte Carlo estimator used in these calculations is based on a control variate approach applied to the sensitivity derivative enhanced sampling. The chaparral fuel model, selected from Rothermel's 11 original fuel models, is studied as an example. We obtain numerical results that improve the crude Monte Carlo sampling by factors as high as three orders of magnitude.
Visualized macrophage dynamics and significance of S100A8 in obese fat
Authors: Sekimoto Ryohei , Fukuda Shiro , Maeda Norikazu , Tsushima Yu , Matsuda Keisuke , Mori Takuya , Nakatsuji Hideaki , Nishizawa Hitoshi , Kishida Ken , Kikuta Junichi , Maijima Yumiko , Funahashi Tohru , Ishii Masaru , Shimomura Iichiro
Published: April 2015

Significance

Infiltration of immune cells into adipose tissue has been observed in obesity, but, until now, these data were based on immunohistological microscopic analysis. Here, to our knowledge for the first time, we applied an intravital multiphoton imaging technique to adipose tissue with lysozyme M-EGFP transgenic (LysM
EGFP
) mice whose EGFP was expressed in the myelomonocytic lineage. Mobility of LysM
EGFP
-positive macrophages was activated just 5 d after high-fat and high-sucrose (HF/HS) diet before the development of obesity. Furthermore, a significant increase of S100A8, one of the alarmins, was detected in fat tissue just 5 d after HF/HS diet. S100A8 stimulated chemotactic migration, and neutralization of S100A8 suppressed the HF/HS diet-induced activation of LysM
EGFP
-positive cells. Time-lapse intravital imaging first identified the very early event exhibiting increased mobility of adipose macrophages.
Effect of neighborhood stigma on economic transactions
Authors: Besbris Max , Faber Jacob William , Rich Peter , Sharkey Patrick
Published: April 2015

Significance

Although previously theorized, virtually no rigorous empirical evidence has demonstrated an impact of neighborhood stigma on individual outcomes. To test for the effects of neighborhood stigma on economic transactions, an experimental audit of an online classified market was conducted in 2013–2014. In this market, advertisements were placed for used iPhones in which the neighborhood of the seller was randomly manipulated. Advertisements identifying the seller as a resident of a disadvantaged neighborhood received significantly fewer responses than advertisements identifying the seller as a resident of an advantaged neighborhood. The results provide strong evidence for an effect of neighborhood stigma on economic transactions, suggesting that individuals carry the stigma of their neighborhood with them as they take part in economic exchanges.
FtsZ filament capping by MciZ, a developmental regulator of bacterial division
Authors: Bisson-Filho Alexandre W. , Discola Karen F. , Castellen Patrícia , Blasios Valdir , Martins Alexandre , Sforça Maurício L. , Garcia Wanius , Zeri Ana Carolina M. , Erickson Harold P. , Dessen Andréa , Gueiros-Filho Frederico J.
Published: April 2015

Significance

Division of bacteria is executed by a contractile ring whose cytoskeletal framework is FtsZ (filamentation temperature-sensitive Z), a protein evolutionarily related to eukaryotic tubulin. The FtsZ ring is made of filaments of head-to-tail FtsZ subunits but its architecture and the rules governing its assembly are still poorly known. Here we show that MciZ, an inhibitor of FtsZ ring formation, functions by capping the minus end of FtsZ filaments. Capping by MciZ makes FtsZ filaments shorter than normal, likely by blocking filament annealing; this represents fundamental information to understand how FtsZ filaments grow and shrink, and attain their normal size. The powerful inhibition of Z-ring assembly by MciZ also suggests that an FtsZ ring cannot form from filaments smaller than a certain size.
New functional insights into the internal architecture of the laminated anchor spicules of
Euplectella aspergillum
Authors: Monn Michael A. , Weaver James C. , Zhang Tianyang , Aizenberg Joanna , Kesari Haneesh
Published: April 2015

Significance

The remarkable properties of biological structural materials can often be attributed to the composite arrangement of their constituents. This paper focuses on the high-aspect-ratio, load-bearing, glassy skeletal fibers (spicules) of the marine sponge
Euplectella aspergillum
. Considering that the spicules’ internal architecture cannot be repaired or remodeled, we hypothesize that there is a connection between their internal structure and their strength. Using a newly developed structural mechanics model for composite beams, we demonstrate that the unique internal geometry that maximizes a beam’s strength correlates well with the geometry observed in the native spicules. This bio-inspired design strategy for increasing a beam's strength has implications for a new generation of man-made structural materials.
Maternal and zygotic
Zfp57
modulate NOTCH signaling in cardiac development
Authors: Shamis Yulia , Cullen Dana E. , Liu Lizhi , Yang Guan , Ng Sheau-Fang , Xiao Lijuan , Bell Fong T. , Ray Chelsea , Takikawa Sachiko , Moskowitz Ivan P. , Cai Chen-Leng , Yang Xiao , Li Xiajun
Published: April 2015

Significance

Abnormal heart development is a common birth defect. Genomic imprinting is absolutely essential for mammalian embryonic development. We found that loss of ZFP57, a master regulator of genomic imprinting, causes a number of heart morphogenetic defects. These cardiac defects are reminiscent of mutant phenotypes observed in the NOTCH signaling pathway, one of the most important pathways in development. Indeed, we demonstrate that NOTCH signaling is diminished without ZFP57. Furthermore, the maternal function of
Zfp57
contributes to NOTCH signaling and embryonic heart development. Maternal and zygotic
Zfp57
play redundant roles in genomic imprinting, NOTCH signaling, and heart development. Thus, our results provide mechanistic links among maternal effect, genomic imprinting, NOTCH signaling, and cardiac development.
Balance between cell−substrate adhesion and myosin contraction determines the frequency of motility initiation in fish keratocytes
Authors: Barnhart Erin , Lee Kun-Chun , Allen Greg M. , Theriot Julie A. , Mogilner Alex
Published: April 2015

Significance

Symmetry breaking and motility initiation are required for many physiological and pathological processes, but the mechanical mechanisms that drive symmetry breaking are not well understood. Fish keratocytes break symmetry spontaneously, in the absence of external cues, with myosin-driven actin flow preceding rear retraction. Here we combine experimental manipulations and mathematical modeling to show that the critical event for symmetry breaking is a flow-dependent, nonlinear switch in adhesion strength. Moreover, our results suggest that mechanical feedback among actin network flow, myosin, and adhesion is sufficient to amplify stochastic fluctuations in actin flow and trigger symmetry breaking. Our mechanical model for symmetry breaking in the relatively simple keratocyte provides a framework for understanding motility initiation in more complex cell types.
Octopamine mediates starvation-induced hyperactivity in adult
Drosophila
Authors: Yang Zhe , Yu Yue , Zhang Vivian , Tian Yinjun , Qi Wei , Wang Liming
Published: April 2015

Significance

The central nervous system monitors reduction in metabolic state and promotes feeding and foraging in response. While feeding behavior has been extensively studied, the regulation of foraging behavior remains largely unknown. In this study, we show that starvation-induced hyperactivity in adult fruit flies resembled foraging activity. We also found that octopamine, the insect counterpart of vertebrate norepinephrine, was crucial for starvation-induced foraging. We further showed that octopamine was not required for starvation-induced changes in feeding, suggesting independent regulations of energy intake behaviors upon starvation. Taken together, our results establish a quantitative foraging assay and a highly conserved neural substrate that regulates foraging, offering an entry point to further dissect the neural circuitry of this important behavior.
GEMM-I riboswitches from
Geobacter
sense the bacterial second messenger cyclic AMP-GMP
Authors: Kellenberger Colleen A. , Wilson Stephen C. , Hickey Scott F. , Gonzalez Tania L. , Su Yichi , Hallberg Zachary F. , Brewer Thomas F. , Iavarone Anthony T. , Carlson Hans K. , Hsieh Yu-Fang , Hammond Ming C.
Published: April 2015

Significance

Bacteria are hidden forces of nature. For example,
Geobacter
bacteria play important roles in geochemistry by reducing metals in the environment. Scientists also are exploring the application of these bacteria toward toxic metal remediation and as “living batteries” that can generate electricity from biowaste. However, there is limited understanding of the signaling pathways that regulate this extracellular metal-reducing activity. Here we have discovered that
Geobacter sulfurreducens
use riboswitch sensors for a signaling molecule called cAG to regulate this process, which is an unexpected finding because cAG was previously associated only with pathogenic bacteria. Furthermore, we have adapted the riboswitch to generate a fluorescent biosensor that can be used to visualize cAG signaling in live bacteria.