bluuebunny/crossref_metadata_2025 huggingface dataset:
Anatomy and Development of the Endodermis and Phellem ofQuercus suberL. Roots
Authors: Machado Adelaide , Pereira Helena , Teixeira Rita Teresa
Published: April 2013

Quercus suberL. has been investigated with special attention to the stem bark and its cork formation layer, but excluding the roots. Roots are the location of infection by pathogens such asPhytophthora cinnamomiresponsible for the tree's sudden death. It is widely accepted that suberin establishes boundaries within tissues, serves as a barrier against free water and ion passage, and works as a shield against pathogen attacks. We followed the suberization of young secondary roots of cork oak. The first suberin deposition detectable by transmission electron microscopy (TEM) and neutral red (NR) was in the endoderm Casparian strips. Casparian strips are not detected by Sudan red 7B and Fluorol yellow (FY) that specifically stain lamellae suberin. Reaction to Sudan was verified in the endodermis and later on in phellem cells that resulted from the phellogen. Under TEM, the Sudan and FY-stained cells showed clear suberin lamellae while the newer formed phellem cells displayed a distinct NR signal compared to the outermost phellem cells. We concluded that suberin chemical components are arranged differently in the cell wall according to the physiological role or maturation stage of a given tissue.
A DR6/p75NTR complex is responsible for β-amyloid-induced cortical neuron death
Authors: Hu Y , Lee X , Shao Z , Apicco D , Huang G , Gong B J , Pepinsky R B , Mi S
Published: April 2013

The p75 neurotrophin receptor (p75NTR) is a known mediator of β-amyloid (Aβ)-induced neurotoxicity implicated in Alzheimer’s disease (AD). Here, we demonstrate that death receptor 6 (DR6) binds to p75NTR and is a component of the p75NTR signaling complex responsible for Aβ-induced cortical neuron death. Cortical neurons isolated from either DR6 or p75NTR null mice are resistant to Aβ-induced neurotoxicity. Blocking DR6 function in cortical neurons by anti-DR6 antibodies that block the binding of DR6 to p75NTR receptor complex or by a dominant negative DR6 construct lacking the cytoplasmic signaling death domain attenuates Aβ-induced caspase 3 activation and cell death. DR6 expression is upregulated in AD cortex and correlates with elevated neuronal death. Targeting the disruption of the DR6/p75NTR complex to prevent Aβ cytotoxicity represents a new approach for the treatment of neurodegenerative disorders such as AD.
Effects of environmental variation and spatial distance on Bacteria, Archaea and viruses in sub-polar and arctic waters
Authors: Winter Christian , Matthews Blake , Suttle Curtis A
Published: April 2013

We investigated the influence of environmental parameters and spatial distance on bacterial, archaeal and viral community composition from 13 sites along a 3200-km long voyage from Halifax to Kugluktuk (Canada) through the Labrador Sea, Baffin Bay and the Arctic Archipelago. Variation partitioning was used to disentangle the effects of environmental parameters, spatial distance and spatially correlated environmental parameters on prokaryotic and viral communities. Viral and prokaryotic community composition were related in the Labrador Sea, but were independent of each other in Baffin Bay and the Arctic Archipelago. In oceans, the dominant dispersal mechanism for prokaryotes and viruses is the movement of water masses, thus, dispersal for both groups is passive and similar. Nevertheless, spatial distance explained 7–19% of the variation in viral community composition in the Arctic Archipelago, but was not a significant predictor of bacterial or archaeal community composition in either sampling area, suggesting a decoupling of the processes regulating community composition within these taxonomic groups. According to the metacommunity theory, patterns in bacterial and archaeal community composition suggest a role for species sorting, while patterns of virus community composition are consistent with species sorting in the Labrador Sea and suggest a potential role of mass effects in the Arctic Archipelago. Given that, a specific prokaryotic taxon may be infected by multiple viruses with high reproductive potential, our results suggest that viral community composition was subject to a high turnover relative to prokaryotic community composition in the Arctic Archipelago.
Intercalation of a molybdenum η3-allyl dicarbonyl complex in a layered double hydroxide and catalytic performance in olefinepoxidation
Authors: Gomes Ana C. , Bruno Sofia M. , Gamelas Carla A. , Valente Anabela A. , Abrantes Marta , Gonçalves Isabel S. , Romão Carlos C. , Pillinger Martyn
Published: April 2013

The direct synthesis of a well-defined layered double hydroxide hybrid assembly comprising intercalated molybdenum carbonyl guest complexes is reported.
Methyl rotor dependent vibrational interactions in toluene
Authors: Gascooke Jason R. , Lawrance Warren D.
Published: April 2013

The methyl rotor dependence of a three state Fermi resonance in S1 toluene at ∼460 cm−1 has been investigated using two-dimensional laser induced fluorescence. An earlier time-resolved study has shown the Fermi resonance levels to have different energy spacings at the two lowest methyl rotor states, m = 0 and 1 [J. A. Davies, A. M. Green, and K. L. Reid, Phys. Chem. Chem. Phys. 12, 9872 (2010)]. The overlapped m = 0 and 1 spectral features have been separated to provide direct spectral evidence for the m dependence of the resonance. The resonance has been probed at m = 3a″1 for the first time and found to be absent, providing further evidence for a large change in the interaction with m. Deperturbing the resonance at m = 0 and 1 reveals that the m dependence arises through differences in the separations of the “zero-order,” locally coupled states. It is shown that this is the result of the local “zero-order” states being perturbed by long-range torsion-vibration coupling that shifts their energy by small amounts. The m dependence of the shifts arises from the Δm = ±3n (n = 1, 2, …) coupling selection rule associated with torsion-rotation coupling in combination with the m2 scaling of the rotor energies, which changes the ΔE for the interaction for each m. There is also an increase in the number of states that can couple to m = 1 compared with m = 0. Consideration of the magnitude of reported torsion-rotation coupling constants suggests that this effect is likely to be pervasive in molecules with methyl rotors.
Quantum control of a model qubit based on a multi-layered quantum dot
Authors: Ferrón Alejandro , Serra Pablo , Osenda Omar
Published: April 2013

In this work we present a model qubit whose basis states are eigenstates of a multi-layered quantum dot. We show that the proper design of the quantum dot results in qubit states that have excellent dynamical properties when a time-dependent driving is applied to it. In particular, it is shown that a simple sinusoidal driving is sufficient to obtain good quality Rabi oscillations between the qubit states. Moreover, the switching between states can be performed with very low leakage, even under off-resonance conditions. In this sense, the quantum control of the qubit is robust under some perturbations and achieved with simple means. More precisely, in this article, we propose a device that is within the reach of current semiconductor technology, a ZnS/CdSe/ZnS/CdSe/ZnS layered quantum dot. In addition, in order to clarify, we show a more general and theoretical model, which we believe is helpful in order to search the ideal experimental device.
Vibrations of the low energy states of toluene ($\tilde X$X̃ 1A1 and $\tilde A$Ã 1B2) and the toluene cation ($\tilde X$X̃ 2B1)
Authors: Gardner Adrian M. , Green Alistair M. , Tamé-Reyes Victor M. , Wilton Victoria H. K. , Wright Timothy G.
Published: April 2013

We commence by presenting an overview of the assignment of the vibrational frequencies of the toluene molecule in its ground (S0) state. The assignment given is in terms of a recently proposed nomenclature, which allows the ring-localized vibrations to be compared straightforwardly across different monosubstituted benzenes. The frequencies and assignments are based not only on a range of previous work, but also on calculated wavenumbers for both the fully hydrogenated (toluene-h8) and the deuterated-methyl group isotopologue (α3-toluene-d3), obtained from density functional theory (DFT), including artificial-isotope shifts. For the S1 state, one-colour resonance-enhanced multiphoton ionization (REMPI) spectroscopy was employed, with the vibrational assignments also being based on previous work and time-dependent density functional theory (TDDFT) calculated values; but also making use of the activity observed in two-colour zero kinetic energy (ZEKE) spectroscopy. The ZEKE experiments were carried out employing a (1 + 1′) ionization scheme, using various vibrational levels of the S1 state with an energy <630 cm‑1 as intermediates; as such we only discuss in detail the assignment of the REMPI spectra at wavenumbers <700 cm‑1, referring to the assignment of the ZEKE spectra concurrently. Comparison of the ZEKE spectra for the two toluene isotopologues, as well as with previously reported dispersed-fluorescence spectra, and with the results of DFT calculations, provide insight both into the assignment of the vibrations in the S1 and D0+ states, as well as the couplings between these vibrations. In particular, insight into the nature of a complicated Fermi resonance feature at ∼460 cm‑1 in the S1 state is obtained, and Fermi resonances in the cation are identified. Finally, we compare activity observed in both REMPI and ZEKE spectroscopy for both toluene isotopologues with that for fluorobenzene and chlorobenzene.
Additional global internal contraction in variations of multireference equation of motion coupled cluster theory
Authors: Demel Ondřej , Datta Dipayan , Nooijen Marcel
Published: April 2013

Extensions of multireference equation of motion coupled cluster theory (MR-EOMCC) [D. Datta and M. Nooijen, J. Chem. Phys. 137, 204107 (2012)]10.1063/1.4766361 are presented that include additional correlation effects into the global, internally contracted similarity transformation, induced by the cluster operators. As a result the final uncontracted diagonalization space can be more compact than in the parent MR-EOMCC approach. A wide range of applications, including transition metal atomic excitation spectra, a large set of valence excited states of organic compounds, and potential energy surfaces of ground and excited states of butadiene, is presented to benchmark the applicability of the parent MR-EOMCC methodology and its new variations.
Effects of sintered powder structural thickness on thin-film evaporation heat transfer at low superheat levels
Authors: Han Lee Cho , Yang Tsai Yao
Published: April 2013

To investigate the correlation between thin-film evaporation heat transfer and structural thickness, this study develops a novel facility and method. The experiment reveals the effects of structural thickness at low superheat levels. The experimental results are integrated into figures for the thickness design of sintered powder structures in two-phase heat transfer devices. The facility includes features such as data acquisition at a high sampling rate, heat loss control, directly sintered specimens, stable environment pressure loops, and visualization techniques. Six types of powder were sintered, including powders 45 μm, 75 μm, and 150 μm in diameter and spheral or dendritic powder shapes. The experimental results show that heat flux increases with increased superheat at low superheat levels with temperature differences lower than 6 °C. At the same superheat levels, heat flux decreases proportionally to the thicker thickness of the sintered powder structure in all six types of powder. Therefore, thicker structures increase thermal resistance, requiring a higher temperature difference to transfer the same amount of heat. Furthermore, thin-film evaporation occurs at a low level of superheat, which can dissipate heat at high heat density or during low levels of superheat.
Optical properties of nonpolar III-nitrides for intersubband photodetectors
Authors: Feezell Daniel , Sharma Yagya , Krishna Sanjay
Published: April 2013

We compare the theoretical optical properties of intersubband transitions for polar III-nitrides, nonpolar III-nitrides, and conventional GaAs. We calculate and examine the peak transition wavelengths, dipole matrix elements, and absorption spectra as a function of quantum well thickness for single quantum well structures on each platform. We show that the absence of polarization-related electric fields in nonpolar III-nitrides simplifies device design and facilitates clear performance advantages over conventional polar III-nitrides, including access to a wider range of absorption wavelengths, a several-fold increase in the dipole matrix element, and higher absorption probability. Compared to conventional GaAs-based structures, nonpolar III-nitrides exhibit a somewhat lower absorption probability but allow for a significantly wider design space, permitting devices operating at wavelengths that are unattainable using GaAs.
Quantum-to-classical rate distortion coding
Authors: Datta Nilanjana , Hsieh Min-Hsiu , Wilde Mark M. , Winter Andreas
Published: April 2013

We establish a theory of quantum-to-classical rate distortion coding. In this setting, a sender Alice has many copies of a quantum information source. Her goal is to transmit a classical description of the source, obtained by performing a measurement on it, to a receiver Bob, up to some specified level of distortion. We derive a single-letter formula for the minimum rate of classical communication needed for this task. We also evaluate this rate in the case in which Bob has some quantum side information about the source. Our results imply that, in general, Alice's best strategy is a non-classical one, in which she performs a collective measurement on successive outputs of the source.
Microstructure and magnetic properties of FINEMET nanowires
Authors: Chiriac H. , Corodeanu S. , Óvári T.-A. , Lupu N.
Published: April 2013

FINEMET (Fe73.5Cu1Nb3Si13.5B9) glass-coated nanowires and submicron wires with metallic nucleus diameters (Φm) between 100 and 500 nm and the glass coating thickness (tg) of 5 μm are reported for the first time. The microstructure of annealed ultrathin glass-coated wires evolves into a nanocrystalline one (DO3 nanograins of 10–20 nm embedded into the residual amorphous matrix) after annealing at 550 °C and 600 °C for 60 min. Despite the similar size of the nanograins, the volume occupied by them relative to the total volume increases from 50%–53% after annealing at 550 °C to 63%–65% after annealing at 600 °C, due to the increase in their number. This is reflected in a more accurate manner in the domain wall velocity measurements than in variation of the magnetic characteristics such as M(H), relative magnetic permeability or switching field. The magnetically softest nanocrystalline phase is formed at larger values of annealing temperature (Ta) for thinner wires, since larger temperature is needed to grow a sufficient number of DO3 grains at distances below the exchange length among them.
Magnetization reversal and enhanced tunnel magnetoresistance ratio in perpendicular magnetic tunnel junctions based on exchange spring electrodes
Authors: Wang Yi , Yin Xiaolu , Le Roy D. , Jiang Jun , Wei H. X. , Liou S. H. , Han X. F.
Published: April 2013

The [Co/Pt]n multilayer based perpendicular magnetic tunnel junction stacks with wedged Co60Fe20B20 insertions up to 2 nm, and corresponding perpendicular magnetic tunnel junctions were magnetically and electrically investigated. The focus is on the influence of CoFeB insertions in the free and reference electrodes on the overall junction magnetization reversal and magnetoresistance response. The exchange spring behavior was revealed as the Co60Fe20B20 spins canting towards the in-plane direction in the [Co/Pt]n/Co60Fe20B20 hard/soft perpendicular magnetic electrodes. The broad range thickness of wedged Co60Fe20B20 insertion enables to reveal the critical transition, in particular, from rigid coupling to exchange spring coupling. With the help of 375°C annealing under 10 kOe magnetic field, the recovery from distinct multi-domain structure to nearly single domain structure was distinctly observed in the unpatterned perpendicular magnetic tunnel junction (p-MTJ) films with CoFeB thickness tCFB≥1.5 nm. Meanwhile, for the corresponding patterned perpendicular magnetic tunnel junctions with AlOx barrier, the tunnel magnetoresistance (TMR) ratio exhibited an intense enhancement over 100%. The TMR results and spin configurations were illustrated using an exchange spring model in both magnetic electrodes. The presented study shows the benefit of using exchange spring magnetic electrodes in perpendicular magnetic tunnel junction on their performance.
Exchange bias and asymmetric magnetization reversal in ultrathin Fe films grown on GaAs (001) substrates
Authors: Tivakornsasithorn K. , Alsmadi A. M. , Liu X. , Leiner J. C. , Choi Y. , Keavney D. J. , Eid K. F. , Dobrowolska M. , Furdyna J. K.
Published: April 2013

Magnetization measurements on a series of Fe films grown by molecular beam epitaxy on GaAs (001) substrates and capped with a thin Au layer reveal interesting exchange bias (EB) properties at low temperatures. The observed exchange bias decreases rapidly with increasing temperature, and completely disappears above 30 K. While the Fe samples were not grown with an intentionally deposited antiferromagnetic (AFM) layer, X-ray reflectometry, X-ray absorption near-edge spectroscopy carried out near the L-edge of Fe, and comparison with similar Fe/GaAs samples capped with Al, which do not show exchange bias, suggest that the exchange bias in the GaAs/Fe/Au multilayers is caused by an AFM Fe oxide at the Fe/Au interface formed by penetration of oxygen through the Au capping layer. The observed exchange bias is accompanied by a strikingly asymmetric magnetization reversal of the Fe films occurring when the magnetic field is applied at angles away from the easy axis of the film. The observed asymmetry can be interpreted in terms of a competition between cubic, uniaxial, and unidirectional magnetic anisotropy characteristic of the exchange-biased Fe film.
A diffracted-beam monochromator for long linear detectors in X-ray diffractometers with Bragg-Brentano parafocusing geometry
Authors: van der Pers N. M. , Hendrikx R. W. A. , Delhez R. , Böttger A. J.
Published: April 2013

A new diffracted-beam monochromator has been developed for Bragg-Brentano X-ray diffractometers equipped with a linear detector. The monochromator consists of a cone-shaped graphite highly oriented pyrolytic graphite crystal oriented out of the equatorial plane such that the parafocusing geometry is preserved over the whole opening angle of the linear detector. In our standard setup a maximum wavelength discrimination of 3% is achieved with an overall efficiency of 20% and a small decrease in angular resolution of only 0.02 °2θ. In principle, an energy resolution as low as 1.5% can be achieved.
Luminescence from edge fracture in shocked lithium fluoride crystals
Authors: Turley W. D. , Stevens G. D. , Capelle G. A. , Grover M. , Holtkamp D. B. , LaLone B. M. , Veeser L. R.
Published: April 2013

Light emitted from a [100] lithium fluoride crystal was characterized under shock wave compression to 28 GPa followed by complete stress release at the edges. The light was examined using time-gated optical spectrometry and imaging, time-resolved optical emission measurements, and hydrodynamic modeling. The shock arrival at the circumference of the crystal was delayed relative to the center so that the two regions could be studied at different times. The majority of the light emission originated when the shock waves released at the circumference of the crystal. Unlike previously reported results for shocked lithium fluoride, we found that the light spectrum is not strictly broad band, but has spectral lines associated with atomic lithium in addition to a broad band background. Also, the emission spectrum depends strongly on the gas surrounding the sample. Based on our observations, the line emission appears to be related to fracture of the lithium fluoride crystal from the shock wave releasing at the edges. Experimenters frequently utilize lithium fluoride crystals as transparent windows for observing shock compressed samples. Because of the experimental geometries used, the shock wave in such cases often reaches the circumference of the window at nearly the same moment as when it reaches the center of the sample-window interface. Light generated at the circumference could contaminate the measurement at the interface when this light scatters into the observed region. This background light may be reduced or avoided using experimental geometries which delay the arrival of the shock wave at the edges of the crystal.
Pressure induced structural phase transformation in TiN: A first-principles study
Authors: Bhat Soumya S. , Waghmare Umesh V. , Ramamurty U.
Published: April 2013

Titanium nitride (TiN), which is widely used for hard coatings, reportedly undergoes a pressure-induced structural phase transformation, from a NaCl to a CsCl structure, at ∼7 GPa. In this paper, we use first-principles calculations based on density functional theory with a generalized gradient approximation of the exchange correlation energy to determine the structural stability of this transformation. Our results show that the stress required for this structural transformation is substantially lower (by more than an order of magnitude) when it is deviatoric in nature vis-à-vis that under hydrostatic pressure. Local stability of the structure is assessed with phonon dispersion determined at different pressures, and we find that CsCl structure of TiN is expected to distort after the transformation. From the electronic structure calculations, we estimate the electrical conductivity of TiN in the CsCl structure to be about 5 times of that in NaCl structure, which should be observable experimentally.
A muon spin relaxation study of the metal-organic magnet Ni(TCNQ)2
Authors: Berlie Adam , Terry Ian , Giblin Sean , Lancaster Tom , Szablewski Marek
Published: April 2013

An investigation of the magnetism of the deuterated form of the metal-organic ferromagnet Ni(TCNQ)2 using the muon spin relaxation technique, is reported. Ni(TCNQ-D4)2 was synthesized in a similar manner to the protio-form, and the crystalline product formed was found to have a Curie temperature of TC=20 K. This transition temperature was 18% larger than that of the protio-form synthesized in our laboratory. Muon spin relaxation measurements were performed in Zero Field (ZF) and in Longitudinal Fields (LF) of up to 0.45 T. The ZF data confirmed that the sample undergoes a bulk ferromagnetic transition at a temperature similar to that observed by the bulk magnetization data. However, ZF measurements also showed that another transition occurs below approximately 6 K, which is believed to be a transition to a magnetic glassy state. The LF results indicate that a significant dynamical component to the magnetism is present below TC as LF fields up to 0.45 T cannot completely re-polarise the spins of the implanted muons. Moreover, at 5 mT, the data can be fit using a damped oscillatory function. Taken together, the ZF and LF results suggest the presence of two dominant sites for implanted muons, one of which is strongly coupled to the bulk magnetic transition and the other that is more weakly coupled and has a dynamical magnetic environment below TC. Such a situation may be a consequence of muon spin relaxation probing core and surface magnetic environments of nanoparticles or clusters.
Nonuniversal critical behavior in a disorder-destroyed charge-ordering system of Pr0.3Nd0.2Sr0.5MnO3
Authors: Zhang P. , Thanh T. D. , Phan The-Long , Yu S. C.
Published: April 2013

Disorder-induced collapse of the charge-ordered state was found in a half-hole-doped manganite Pr0.3Nd0.2Sr0.5MnO3 by means of studying the magnetic and critical behaviors. Large magnetic frustration originated from the strong competition between ferromagnetic and antiferromagnetic interactions led to the absence of long-range charge ordering. The critical exponents determined for the ferromagnetic-to-paramagnetic phase transition by employing the Kouvel-Fisher method are not consistent with any universality classes, but in between the mean-field and 3D Heisenberg models. It is suggested that the Pr/Nd-site disorder destabilizes the charge-ordered state, and breaks the long-range charge-ordering system into the fragment of antiferromagnetic clusters, which coexist with the ferromagnetic background. Such ionic disorder-induced highly magnetic inhomogeneity is responsible for the nonuniversal critical behavior.
Thermal equation of state to 33.5 GPa and 1673 K and thermodynamic properties of tungsten
Authors: Litasov Konstantin D. , Gavryushkin Pavel N. , Dorogokupets Peter I. , Sharygin Igor S. , Shatskiy Anton , Fei Yingwei , Rashchenko Sergey V. , Seryotkin Yury V. , Higo Yiji , Funakoshi Kenichi , Ohtani Eiji
Published: April 2013

A comprehensive P-V-T dataset for bcc-tungsten was obtained for pressures up to 33.5 GPa and temperatures 300–1673 K using MgO and Au pressure scales. The thermodynamic analysis of these data was performed using high-temperature (HT) and Mie-Grüneisen-Debye (MGD) relations combined with the Vinet equations of state (EOS) for room-temperature isotherm and the newly proposed Kunc-Einstein (KE) EOS. The KE EOS allowed calibration of W thermodynamic parameters to the pressures of at least 300 GPa and temperatures up to 4000 K with minor uncertainties (<1% in calculated volume of W). A detailed analysis of room-temperature compression data with Vinet EOS yields V0 = 31.71 ± 0.02 Å3, KT = 308 ± 1 GPa, and KT′  = 4.20 ± 0.05. Estimated thermoelastic parameters for HT include (∂KT/∂T)P = −0.018 ± 0.001 GPa/K and thermal expansion α = a0 + a1T with a0 = 1.35 (±0.04) × 10−5 K−1 and a1 = 0.21 (±0.05) × 10−8 K−2. Fitting to the MGD relation yielded γ0 = 1.81 ± 0.02 and q = 0.71 ± 0.02 with the Debye temperature (θ0,) fixed at 370–405 K. The parameters for KE EOS include two Einstein temperatures, ΘE1o = 314 K and ΘE2o = 168 K, Grüneisen parameter at ambient condition γ0 = 1.67 and infinite compression γ∞ = 0.66, with β = 1.16 (which is a power-mode parameter in the Grüneisen equation), anharmonicity (m = 3.57) and electronic (g = 0.11) equivalents of the Grüneisen parameter, and additional parameters for intrinsic anharmonicity, a0 = 6.2 × 10−5 K−1, and electronic contribution, e0 = 4.04 × 10−5 K−1 to the free energy. Fixed parameters include k = 2 in KE EOS and mE1 = mE2 = 1.5 in expression for Einstein temperature. Present analysis should represent the best fit of the experimental data for W and can be used for a variety of thermodynamic calculations for W and W-containing systems including phase diagrams, chemical reactions, and electronic structure.
The role of internal structure in the anomalous switching dynamics of metal-oxide/polymer resistive random access memories
Authors: Rocha Paulo R. F. , Kiazadeh Asal , De Leeuw Dago M. , Meskers Stefan C. J. , Verbakel Frank , Taylor David M. , Gomes Henrique L.
Published: April 2013

The dynamic response of a non-volatile, bistable resistive memory fabricated in the form of Al2O3/polymer diodes has been probed in both the off- and on-state using triangular and step voltage profiles. The results provide insight into the wide spread in switching times reported in the literature and explain an apparently anomalous behaviour of the on-state, namely the disappearance of the negative differential resistance region at high voltage scan rates which is commonly attributed to a “dead time” phenomenon. The off-state response follows closely the predictions based on a classical, two-layer capacitor description of the device. As voltage scan rates increase, the model predicts that the fraction of the applied voltage, Vox, appearing across the oxide decreases. Device responses to step voltages in both the off- and on-state show that switching events are characterized by a delay time. Coupling such delays to the lower values of Vox attained during fast scan rates, the anomalous observation in the on-state that, device currents decrease with increasing voltage scan rate, is readily explained. Assuming that a critical current is required to turn off a conducting channel in the oxide, a tentative model is suggested to explain the shift in the onset of negative differential resistance to lower voltages as the voltage scan rate increases. The findings also suggest that the fundamental limitations on the speed of operation of a bilayer resistive memory are the time- and voltage-dependences of the switch-on mechanism and not the switch-off process.
Magnetic and transport properties of tetragonal- or cubic-Heusler-type Co-substituted Mn-Ga epitaxial thin films
Authors: Kubota T. , Ouardi S. , Mizukami S. , Fecher G. H. , Felser C. , Ando Y. , Miyazaki T.
Published: April 2013

The composition dependence of the structural, magnetic, and transport properties of epitaxially grown Mn-Co-Ga films were investigated. The crystal structure was observed to change from tetragonal to cubic as the Co content was increased. In terms of the dependence of saturation magnetization on the Co content, relatively small value was obtained for the Mn2.3Co0.4Ga1.3 film at a large Ku value of 9.2 Merg/cm3. Electrical resistivity of Mn-Co-Ga films was larger than that of pure Mn-Ga film. The maximum value of the resistivity was 490 μΩcm for Mn2.2Co0.6Ga1.2 film. The high resistivity of Mn-Co-Ga might be due to the presence of localized electron states in the films due to chemical disordering caused by the Co substitution.
Fullerene concentration dependent bimolecular recombination in organic photovoltaic films
Authors: Kaake Loren G. , Sun Yanming , Bazan Guillermo C. , Heeger Alan J.
Published: April 2013

Organic photovoltaic devices made of a solution processed small molecule and a fullerene show a decrease in short circuit current with decreasing fullerene amounts. Transient absorption experiments show that the rate of bimolecular recombination increases as the system is deprived of fullerene. A simple expression for the bimolecular recombination coefficient derived by accounting for intrinsic carrier generation reproduces the observed behavior.
Tuning magnetic anisotropy in (001) oriented L1 (Fe1−xCux)55Pt45 films
Authors: Gilbert Dustin A. , Wang Liang-Wei , Klemmer Timothy J. , Thiele Jan-Ulrich , Lai Chih-Huang , Liu Kai
Published: April 2013

We have achieved (001) oriented L10 (Fe1−xCux)55Pt45 thin films, with magnetic anisotropy up to 3.6 × 107 erg/cm3, using atomic-scale multilayer sputtering and post annealing at 400 °C for 10 s. By fixing the Pt concentration, structure and magnetic properties are systematically tuned by the Cu addition. Increasing Cu content results in an increase in the tetragonal distortion of the L10 phase, significant changes to the film microstructure, and lowering of the saturation magnetization and anisotropy. The relatively convenient synthesis conditions, along with the tunable magnetic properties, make such materials highly desirable for future magnetic recording technologies.
Super-Planckian near-field thermal emission with phonon-polaritonic hyperbolic metamaterials
Authors: Biehs S.-A. , Tschikin M. , Messina R. , Ben-Abdallah P.
Published: April 2013

We study super-Planckian near-field heat exchanges for multilayer hyperbolic metamaterials using exact scattering-matrix (S-matrix) calculations. We investigate heat exchanges between two multilayer hyperbolic metamaterial structures. We show that the super-Planckian emission of such metamaterials can either come from the presence of surface phonon-polariton modes or from a continuum of hyperbolic modes depending on the choice of composite materials as well as the structural configuration.
Bending stress induced improved chemiresistive gas sensing characteristics of flexible cobalt-phthalocyanine thin films
Authors: Singh Ajay , Kumar Ashwini , Kumar Arvind , Samanta S. , Joshi Nirav , Balouria Vishal , Debnath A. K. , Prasad R. , Salmi Z. , Chehimi M. M. , Aswal D. K. , Gupta S. K.
Published: April 2013

We report chemiresistive gas sensing characteristics of cobalt phthalocyanine films deposited on flexible bi-axially oriented polyethylene terephthalate substrates. Charge carrier mobility in these films systematically decreases upon bending, which implies that bending reduces π-π interactions among molecules. At room temperature, these films exhibited a reversible change in resistance on exposure to ammonia (5–50 ppm) along with high sensitivity and selectivity as well as fast response and recovery. The chemiresistive sensing properties were found to improve significantly under bend conditions owing to creation of more numbers of interaction sites.
Josephson vortex coupled to a flux qubit
Authors: Fedorov Kirill G. , Shcherbakova Anastasia V. , Schäfer Roland , Ustinov Alexey V.
Published: April 2013

Experiments towards realizing a readout of superconducting qubits by using ballistic Josephson vortices are reported. We measured the microwave radiation induced by a fluxon moving in an annular Josephson junction. By coupling a flux qubit as a current dipole to the annular junction, we detect periodic variations of the fluxon's oscillation frequency versus magnetic flux through the qubit. We found that the scattering of a fluxon on a current dipole can lead to the acceleration of a fluxon regardless of a dipole polarity. We use the perturbation theory and numerical simulations of the perturbed sine-Gordon equation to analyze our results.
Funnel metadynamics as accurate binding free-energy method
Authors: Limongelli Vittorio , Bonomi Massimiliano , Parrinello Michele
Published: April 2013

A detailed description of the events ruling ligand/protein interaction and an accurate estimation of the drug affinity to its target is of great help in speeding drug discovery strategies. We have developed a metadynamics-based approach, named funnel metadynamics, that allows the ligand to enhance the sampling of the target binding sites and its solvated states. This method leads to an efficient characterization of the binding free-energy surface and an accurate calculation of the absolute protein–ligand binding free energy. We illustrate our protocol in two systems, benzamidine/trypsin and SC-558/cyclooxygenase 2. In both cases, the X-ray conformation has been found as the lowest free-energy pose, and the computed protein–ligand binding free energy in good agreement with experiments. Furthermore, funnel metadynamics unveils important information about the binding process, such as the presence of alternative binding modes and the role of waters. The results achieved at an affordable computational cost make funnel metadynamics a valuable method for drug discovery and for dealing with a variety of problems in chemistry, physics, and material science.
TheDrosophilaF-box protein dSkp2 regulates cell proliferation by targeting Dacapo for degradation
Authors: Dui Wen , Wei Bin , He Feng , Lu Wei , Li Changqing , Liang Xuehong , Ma Jun , Jiao Renjie
Published: April 2013

Cell cycle progression is controlled by a complex regulatory network consisting of interacting positive and negative factors. In humans, the positive regulator Skp2, an F-box protein, has been a subject of intense investigation in part because of its oncogenic activity. By contrast, the molecular and developmental functions of its Drosophila homologue, dSkp2, are poorly understood. Here we investigate the role of dSkp2 by focusing on its functional relationship with Dacapo (Dap), the Drosophila homologue of the cyclin-dependent kinase inhibitors p21cip1/p27kip1/p57kip2. We show that dSkp2 interacts physically with Dap and has a role in targeting Dap for ubiquitination and proteasome-mediated degradation. We present evidence that dSkp2 regulates cell cycle progression by antagonizing Dap in vivo. dSkp2 knockdown reduces cell density in the wing by prolonging the cell doubling time. In addition, the wing phenotype caused by dSkp2 knockdown resembles that caused by dap overexpression and can be partially suppressed by reducing the gene dose of dap. Our study thus documents a conserved functional relationship between dSkp2 and Dap in their control of cell cycle progression, suggesting the possibility of using Drosophila as a model system to study Skp2-mediated tumorigenesis.
Strengthening State Capabilities: The Role of Financial Incentives in the Call to Public Service*
Authors: Dal Bó Ernesto , Finan Frederico , Rossi Martín A.
Published: April 2013

We study a recent recruitment drive for public sector positions in Mexico. Different salaries were announced randomly across recruitment sites, and job offers were subsequently randomized. Screening relied on exams designed to measure applicants’ intellectual ability, personality, and motivation. This allows the first experimental estimates of (1) the role of financial incentives in attracting a larger and more qualified pool of applicants, (2) the elasticity of the labor supply facing the employer, and (3) the role of job attributes (distance, attractiveness of the municipal environment) in helping fill vacancies, as well as the role of wages in helping fill positions in less attractive municipalities. A theoretical model of job applications and acceptance guides the empirical inquiry. We find that higher wages attract more able applicants as measured by their IQ, personality, and proclivity toward public sector work—that is, we find no evidence of adverse selection effects on motivation; higher wage offers also increased acceptance rates, implying a labor supply elasticity of around 2 and some degree of monopsony power. Distance and worse municipal characteristics strongly decrease acceptance rates, but higher wages help bridge the recruitment gap in worse municipalities.
Evolution of the Levels of Free Radicals Generated on Wheat Flour and Wheat Bran by Electron Beam
Authors: Braşoveanu Mirela , Crăciun Gabriela , Mănăilă Elena , Ighigeanu Daniel , Nemţanu Monica R. , Grecu Maria N.
Published: April 2013

This paper presents the experimental data regarding the levels of free radicals investigated by electron spin resonance (ESR) on wheat flour and wheat bran exposed to an electron beam. Samples were irradiated with an electron linear accelerator of 6 MeV and then stored at room temperature in air. ESR spectra of the samples indicated presence of free radicals induced by electron beam. Three types of free radicals have been detected in wheat flour, and signals typical for cellulose‐like radicals have been noticed for wheat bran, their concentration increasing with the irradiation dose. The postirradiation storage of both sample types caused radical decay with a two‐step pattern associated with fast decay of short‐life radicals followed by slow reduction of long‐life radicals. However, in the first step, the irradiated wheat bran exhibited more rapid decay of radicals than irradiated flour owing to their different complex matrixes, which led to paramagnetic structures of different origin after exposure to an electron beam. The ESR technique allows the detection of free radicals induced in wheat flour and bran by electron beam for a limited period after irradiation that could be shorter than the shelf life of the products.
Correlation Between Spinal Cord Function Assessed by Intraoperative SCEPs and Morphology of the Compressed Spinal Cord on MRI
Authors: Kanchiku Tsukasa , Imajo Yasuaki , Suzuki Hidenori , Yoshida Yuichiro , Akashi Kosuke , Taguchi Toshihiko
Published: April 2013

Study Design:

Retrospective study.

Objectives:

The objective of this study was to examine whether the morphology of the compressed spinal cord reflects spinal cord dysfunction in cervical spondylotic myelopathy (CSM).

Summary of Background:

Segmental levels responsible for clinical symptoms in CSM are usually diagnosed by neurological examination and imaging studies such as magnetic resonance imaging (MRI). Electrophysiological examination makes it possible to assess the spinal cord function quantitatively. There are few detailed studies about correlation between intraoperative spinal cord–evoked potentials (following SCEPs) and preoperative MRI.

Materials and Methods:

A total of 25 CSM cases diagnosed with single intervertebral dysfunction based on preoperative neurological findings and intraoperative SCEPs were included. We recorded 3 different SCEPs and divided the cases into 2 groups: the transverse type (T-type) (n=18) that had abnormalities in all SCEPs; and the upper limbs sensory (abnormal only for MN-SCEPs) and posterolateral (abnormalities in the MN-SCEPs and Tc-SCEPs) type (US-PL-type) (n=7) that had abnormalities other than SCEPs following thoracic spinal cord stimulation. Morphometry was performed on MRI T1-weighed axial images. Clinical preoperative impairment was evaluated using the Japanese Orthopedic Association score.

Results:

The average Japanese Orthopedic Association score of T-type cases was 8.1 points and that of US-PL-type cases was 10.5. There were no severe cases with <7 points in the US-PL-type group, but there were 9 cases in the T-type group. By morphometric comparison, both the central and the 1/4-lateral compression ratio were significantly lower in the T-type cases.

Conclusions:

Spinal cord morphology, as observed on MRI in patients with CSM reflected spinal cord dysfunction to some extent and could become the index for functional diagnosis, but it is necessary to consider a dynamic factor.
Comprehensive prediction in 78 human cell lines reveals rigidity and compactness of transcription factor dimers
Authors: Jankowski Aleksander , Szczurek Ewa , Jauch Ralf , Tiuryn Jerzy , Prabhakar Shyam
Published: April 2013

The binding of transcription factors (TFs) to their specific motifs in genomic regulatory regions is commonly studied in isolation. However, in order to elucidate the mechanisms of transcriptional regulation, it is essential to determine which TFs bind DNA cooperatively as dimers and to infer the precise nature of these interactions. So far, only a small number of such dimeric complexes are known. Here, we present an algorithm for predicting cell-type–specific TF–TF dimerization on DNA on a large scale, using DNase I hypersensitivity data from 78 human cell lines. We represented the universe of possible TF complexes by their corresponding motif complexes, and analyzed their occurrence at cell-type–specific DNase I hypersensitive sites. Based on ∼1.4 billion tests for motif complex enrichment, we predicted 603 highly significant cell-type–specific TF dimers, the vast majority of which are novel. Our predictions included 76% (19/25) of the known dimeric complexes and showed significant overlap with an experimental database of protein–protein interactions. They were also independently supported by evolutionary conservation, as well as quantitative variation in DNase I digestion patterns. Notably, the known and predicted TF dimers were almost always highly compact and rigidly spaced, suggesting that TFs dimerize in close proximity to their partners, which results in strict constraints on the structure of the DNA-bound complex. Overall, our results indicate that chromatin openness profiles are highly predictive of cell-type–specific TF–TF interactions. Moreover, cooperative TF dimerization seems to be a widespread phenomenon, with multiple TF complexes predicted in most cell types.
A structural‐phenomenological typology of mind‐matter correlations
Authors: Atmanspacher Harald , Fach Wolfgang
Published: April 2013

We present a typology of mind‐matter correlations embedded in a dual‐aspect monist framework as proposed by Pauli and Jung. They conjectured a picture in which the mental and the material arise as two complementary aspects of one underlying psychophysically neutral reality to which they cannot be reduced and to which direct empirical access is impossible. This picture suggests structural, persistent, reproducible mind‐matter correlations by splitting the underlying reality into aspects. In addition, it suggests induced, occasional, evasive mind‐matter correlations above and below, respectively, those stable baseline correlations. Two significant roles for the concept of meaning in this framework are elucidated. Finally, it is shown that the obtained typology is in perfect agreement with an empirically based classification of the phenomenology of mind‐matter correlations as observed in exceptional human experiences.
Are archetypes transmitted or emergent? A response to Christian Roesler
Authors: Martin‐Vallas François
Published: April 2013

In this paper the author argues that Jung's concept of archetype should not be reduced to an univocal definition. Jung himself proposed many definitions of this concept, some of them being partially or totally contradictory to others. A univocal and logical way of thinking can lead us to refute and reject part of those definitions, but a complex way of thinking, as proposed by Edgar Morin or Roy Bhaskar for example, can allow us to consider that those apparent contradictions in Jung's definitions of archetype reflect the complexity of the psychic reality. The main argument of the author is that Jung was missing the epistemological concept of emergence (which appeared in science at the time of his death) and that he tried to express it with the epistemological concepts of his time.
Antioxidant Activity of Various Solvent Fractions from Edible Brown Alga, Eisenia bicyclis and Its Active Compounds
Authors: Kwon Tae‐Hyung , Kim Tae‐Wan , Kim Choong‐Gon , Park Nyun‐Ho
Published: April 2013

In this study, we aimed to elucidate the antioxidant capacity of Eisenia bicyclis and evaluated its antioxidant activity using various assay systems such as 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, 2,2‐azino‐bis (3‐ethylbenzthiazoline‐6‐sulfonic acid) (ABTS) radical scavenging, reducing power ability, and content of total polyphenol. Among all the performed experiments, the ethyl acetate fraction of E. bicyclis exhibited higher antioxidant activities. From this finding, isolation and purification were performed on the ethyl acetate fraction and identified dieckol and phlorofucofureoeckol‐A by spectroscopic analyses including FAB‐mass in the negative mode, 1H NMR, 13C NMR, 1H‐1H COSY, HMQC, and HMBC spectra. Interestingly, ABTS radical scavenging activities of dieckol and phlorofucofuroeckol showed strong effects of 65.36% and 70.38% at a concentration of 50 μg/mL, respectively. DPPH radical scavenging and reducing power abilities were increased in a dose‐dependent manner at various concentrations. These results suggest that dieckol and phlorofucofuroeckol‐A of E. bicyclis may play an important role in protection from oxidative stress involving reactive oxygen species and may contribute to the development of new bio products, for example, a useful preservative to improve food quality and a drug for various oxidative damage‐associated diseases.

Practical Application: The results suggest that dieckol and phlorofucofuroeckol‐A can be utilized as a natural source for potential application of antioxidant in food industry and drug for oxidative damage‐associated diseases.