bluuebunny/crossref_metadata_2025 huggingface dataset:
The BRIF: Success Factors and Crucial Considerations for Ensuring Impact.
Authors: Miranda Lisa
Published: April 2011

This presentation focused on the potential of the BRIF to capture data that demonstrates the initial and long term impact of bioresources and those who direct/operate them for support/participation in biomedical and clinical research and their effects on clinical care outcomes. The focus of this talk is also to share ideas and provide different ways to look at the BRIF. The BRIF can be used to measure impact but may also be utilized to ensure and accelerate impact. Implementing the BRIF would potentially lead to significant positive downstream effects. Many challenges exist for the biobanking area ahead of this. One central issue that is delaying/impeding impact is the ability to create economically viable and sustainable resources.
Self-assembled naphthalenediimide derivative films for light-assisted electrochemical reduction of oxygen
Authors: Castaldelli Evandro , Triboni Eduardo Rezende , Demets Grégoire Jean-François
Published: April 2011

Electrochemically self-assembled N,N′-(ethyl-N″,N″,N″-dimethyloctadecane ammonium)-1,4,5,8-naphthalene diimide bromide films produce photocurrent with oxygen in water.
Exceptional visible-light-driven photocatalytic activity over BiOBr–ZnFe2O4 heterojunctions
Authors: Kong Liang , Jiang Zheng , Xiao Tiancun , Lu Lufeng , Jones Martin O. , Edwards Peter P.
Published: April 2011

The morphology and activity of the BiOBr–ZnFe2O4 p–n heterojunctions significantly depend on the BiOBr/ZnFe2O4 molar ratio, where the 0.9BiOBr–0.1ZnFe2O4 forms fascinating spheres and shows the highest activity in visible-light-driven photodegradation of Rhodamine B.
Ethanol-assisted multi-sensitive poly(vinyl alcohol) photonic crystal sensor
Authors: Chen Cheng , Zhu Yihua , Bao Hua , Shen Jianhua , Jiang Hongliang , Peng Liming , Yang Xiaoling , Li Chunzhong , Chen Guorong
Published: April 2011

An ethanol-assisted method is utilized to generate a robust gelated crystalline colloidal array (GCCA) photonic crystal sensor. The functionalized sensor efficiently diffracts the visible light and responds to various stimuli.
Ratiometric detection of mercury ions in water: accelerated response kinetics of azochromophores having ethynyl ligand tethers
Authors: Lee Ho Yong , Jo Junyong , Park Hyunsoo , Lee Dongwhan
Published: April 2011

AN,O-bidentate azo chromophore is functionalized with ethynyl groups to show a ratiometric response to mercury(ii) ions in water.
RAGE biology, atherosclerosis and diabetes
Authors: Barlovic Drazenka Pongrac , Soro-Paavonen Aino , Jandeleit-Dahm Karin A. M.
Published: April 2011

Diabetes is characterized by accelerated atherosclerosis with widely distributed vascular lesions. An important mechanism by which hyperglycaemia contributes to vascular injury is through the extensive intracellular and extracellular formation of AGEs (advanced glycation end products). AGEs represent a heterogeneous group of proteins, lipids and nucleic acids, irreversibly cross-linked with reducing sugars. AGEs are implicated in the atherosclerotic process, either directly or via receptor-mediated mechanisms, the most extensively studied receptor being RAGE (receptor for AGEs). The AGE–RAGE interaction alters cellular signalling, promotes gene expression and enhances the release of pro-inflammatory molecules. It elicits the generation of oxidative stress in numerous cell types. The importance of the AGE–RAGE interaction and downstream pathways leading to injurious effects as a result of chronic hyperglycaemia in the development, progression and instability of diabetic atherosclerotic lesions has been amply demonstrated in animal studies. Moreover, the deleterious link of AGEs with diabetic vascular complications has been suggested in many human studies. In the present review, our current understanding of their role as an important mediator of vascular injury through the various stages of atherosclerosis in diabetes will be reviewed and critically assessed.
Growth temperature dependent graphene alignment on Ir(111)
Authors: Hattab H. , N’Diaye A. T. , Wall D. , Jnawali G. , Coraux J. , Busse C. , van Gastel R. , Poelsema B. , Michely T. , Meyer zu Heringdorf F.-J. , Horn-von Hoegen M.
Published: April 2011

The morphology of graphene monolayers on Ir(111) prepared by thermal decomposition of ethylene between 1000 and 1530 K was studied with high resolution low energy electron diffraction. In addition to a well-oriented epitaxial phase, randomly oriented domains are observed for growth temperatures between 1255 and 1460 K. For rotational angles of ±3° around 30° these domains lock-in in a 30° oriented epitaxial phase. Below 1200 K the graphene layer exhibits high disorder and structural disintegrity. Above 1500 K the clear moiré spots reflect graphene in a single orientation epitaxial incommensurate phase.
Influence of viscoelastic property on laser-generated surface acoustic waves in coating–substrate systems
Authors: Sun Hong-xiang , Zhang Shu-yi , Xu Bai-qiang
Published: April 2011

Taking account of the viscoelasticity of materials, the pulsed laser generation of surface acoustic waves in coating–substrate systems has been investigated quantitatively by using the finite element method. The displacement spectra of the surface acoustic waves have been calculated in frequency domain for different coating–substrate systems, in which the viscoelastic properties of the coatings and substrates are considered separately. Meanwhile, the temporal displacement waveforms have been obtained by applying inverse fast Fourier transforms. The numerical results of the normal surface displacements are presented for different configurations: a single plate, a slow coating on a fast substrate, and a fast coating on a slow substrate. The influences of the viscoelastic properties of the coating and the substrate on the attenuation of the surface acoustic waves have been studied. In addition, the influence of the coating thickness on the attenuation of the surface acoustic waves has been also investigated in detail.
Dielectric and structural characterization of high-temperature ferroelectric xBi(Zn1/2Ti1/2)O3−yPbZrO3–zPbTiO3 perovskite ternary solid solution
Authors: Dwivedi Akansha , Randall Clive A.
Published: April 2011

This paper reports the development of a new bismuth and lead oxide–based high-temperature ferroelectric ternary solid solution xBi(Zn1/2Ti1/2)O3−yPbZrO3–zPbTiO3 (xBZT–yPZ–zPT). Structural analysis has been carried out by XRD and SEM. A morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases has been located on a pseudobinary line 0.1BZT–0.9[(1−x)PZ–xPT] within the ternary phase diagram. Dielectric studies of various compositions along the pseudobinary line 0.1BZT–0.9[(1−x)PZ–xPT] have been carried out in a wide range of temperatures from room temperature to 600 °C, on both poled and unpoled samples. Compositions near the MPB exhibit high dielectric permittivity (∼23 000–28 000). Rhombohedral compositions show a diffuse phase transition with a small frequency dispersion. Based on the dielectric properties and differential scanning calorimetry, phase transition trends versus composition along the pseudobinary line 0.1BZT–0.9[(1−x)PZ−xPT] have been demonstrated.
Electronic structures and optical properties of hexagonal boron nitride under hydrostatic pressures
Authors: Hu M. L. , Yin J. L. , Zhang C. X. , Yu Zhizhou , Sun L. Z.
Published: April 2011

Electronic structures and optical properties of hexagonal boron nitride (h-BN) under hydrostatic pressure are studied using density functional theory calculations. Charge density difference, density of states, band structures, and dielectric functions are calculated to reveal the evolution of the electronic structures, band-gap, and optical properties of five typical stackings of h-BN corresponding to the hydrostatic pressures. The band-gap of h-BN decreases with the increasing hydrostatic pressure. The band-gap of h-BN with AA and AF stacking decreases faster than that of the others. The positions of their valence band maximum and the conduction band minimum shift in the Brillouin Zone corresponding to the external hydrostatic pressure, depending on the different stackings. In particular, the band structure of AA becomes direct at 9.19 GPa, which does not occur in other stackings. The band-edge optical absorption thresholds of AA, AD, AE, and AF show the redshift as the pressure increases, except for that of AB stacking, which is fluctuant.
Co2+xFe1−xSi/MgO(001) Heusler alloys: Influence of off-stoichiometry and lattice distortion on the magnetic properties in bulk and on MgO(001)
Authors: Herper H. C. , Krumme B. , Ebke D. , Antoniak C. , Weis C. , Warland A. , Hütten A. , Wende H. , Entel P.
Published: April 2011

We investigate the influence of lattice distortion and off-stoichiometry on the electronic and magnetic properties of Co2+xFe1−xSi Heusler alloys in their L21 bulk phase and on MgO(001) using the density functional theory. Our investigations show that Co excess does not significantly change the magnetic properties, whereas an increase of the Fe content can reduce the spin polarization. In addition, the influence of off-stoichiometry on x-ray absorption spectra is studied. For comparison, x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements have been carried out for Co2FeSi/MgO(001) at the Co and Fe L2,3 edges.
Growth and interface phase stability of barium hexaferrite films on SiC(0001)
Authors: Lazarov V. K. , Hasnip P. J. , Cai Z. , Yoshida K. , Ziemer K. S.
Published: April 2011

We have studied interface phase stability of the BaFe12O19 (BaM) thin films grown by molecular beam epitaxy on SiC(0001). The films were epitaxially grown with the following crystallographic relation: BaM(0001)‖SiC(0001) and BaM(11-20)‖SiC(11−20). High resolution TEM reveals the existence of two interfacial bands with different structure than BaM. The first band close to SiC is SiOx while the second has spinel structure and chemically corresponds to Fe3O4. These findings suggest that at initial growth stages Fe3O4 is more favorable than BaM. Density functional theory modeling of the phase stability of BaM compared to Fe3O4 shows that BaM is only stable at high oxygen partial pressures.
Normal mode analysis of a model semirigid polymer
Authors: ten Bosch A.
Published: April 2011

Dynamic and structural properties of biological polymers are important to their function but it is difficult to obtain information on molecular flexibility at an atomic level. This paper describes how a normal mode analysis can be used to describe the equilibrium and nonequilibrium properties of complex polymer systems such as DNA in solution. A weak coupling between the chain deformation and the local chain orientation simplifies the calculations. A crossover in the normal mode behavior is proposed with a transition from straight rod bend modes to longitudinal oscillations of a coil conformation as a function of the stiffness and the degree of polymerization.
Spin-polarized transport in NiFe/perylene-3,4,9,10-tetracarboxylate/Co organic spin valves
Authors: Palosse M. , Fisichella M. , Bedel-Pereira E. , Séguy I. , Villeneuve C. , Warot-Fonrose B. , Bobo J. F.
Published: April 2011

We have prepared organic spin valves based on the perylene derivative perylene-3,4,9,10-tetracarboxylate (PTCTE) with NiFe and Co ferromagnetic electrodes (with direct or off-axis sample configuration for the Co upper electrode deposition). Transmission electron miscroscopy is employed to study the stacking of the NiFe/PTCTE/Co vertical structures. Tunneling atomic force microscopy reveals that direct deposition of Co damages the PTCTE layer. Moreover, fluorescence and I-V studies of PTCTE evidence changes of the organic layer’s transport properties that are correlated with the deposition rate of PTCTE. Finally, we report up to 3% magnetoresistance at 10 mV and 5 K on a sample with an organic spacer 300 nm in thickness and an off-axis deposited cobalt counter electrode. We analyze this result in terms of spin diffusion and spin precession in PTCTE.
Soft x-ray synchrotron radiation spectroscopy study of CuFe1-xNixO2 (0≤ x ≤0.03) delafossite oxides
Authors: Kim D. H. , Hwang J. H. , Lee K. H. , Kang J.-S. , Nozaki T. , Hayashi K. , Kajitani T. , Park B.-G. , Kim J.-Y. , Min B. I.
Published: April 2011

Electronic structures of Ni-doped CuFe1-xNixO2 delafossite oxides (x = 0, 0.015, and 0.03) have been investigated by employing soft x-ray absorption spectroscopy and soft x-ray magnetic circular dichroism (XMCD). It is found that the valence states of Cu, Fe, and Ni ions are nearly monovalent (Cu+), trivalent (Fe3+), and divalent (Ni2+), respectively, and that they do not change with x. In contrast, the Cu 2p XMCD signals, which arise from the Cu2+ states, increase with increasing x. This study suggests that the increasing XMCD signals are presumably related to the formation of ferrimagnetic spinel impurities in CuFe1-xNixO2.
Magnetic and structural properties of single crystal Fe1−xZnx thin films
Authors: McClure Adam , Rugheimer P. , Idzerda Y. U.
Published: April 2011

Single crystal Fe1−xZnx thin films (x = 0 to 0.85) have been prepared on MgO(001) substrates by molecular beam epitaxy. Reflection high energy electron diffraction monitored the crystal quality of the films in situ and reveals a phase transition of the crystal structure from the α-Fe phase to primarily the Γ phase near a Zn concentration of 40%. Vibrating sample magnetometry shows a lack of any uniaxial anisotropy and a change in sign of the fourth order cubic magnetic anisotropy constant, K1, at a Zn concentration near 40%. The Fe1−xZnx samples maintain the high easy axis remanence and low coercivity of pure iron out to about 40% Zn, at which point the samples show a dramatic increase in coercivity, at least in part due to an increased roughness of the films, as the formation of the Γ phase becomes preferred.
Highly chemical ordered L11 CoPt (111) films with perpendicular anisotropy grown on glass substrates
Authors: Yang Yang , Chen J. S. , Chow G. M.
Published: April 2011

In this study, L11 CoPt (111) films were deposited on glass substrates at 300 °C with observed superlattice (111) and (333) peaks and easy axis distribution of 2°. The magnetic anisotropy constant was in the order of 107 erg/cm3. The effect of CoPt layer thickness on domain structure and magnetic properties was investigated. With increasing film thickness, the squareness was reduced and the nucleation field changed from negative to positive, indicating low impedance to domain wall motion and increased demagnetizing energy. Magnetic force microscopy images demonstrated the magnetic domain structure changed from irregular and large domains to highly interconnected stripes with increasing CoPt layer thickness.
Reducing media noise of perpendicular magnetic recording tape for over-50 TB class data cartridge
Authors: Matsunuma S. , Inoue T. , Watanabe T. , Doi T. , Gomi S. , Mashiko Y. , Hirata K. , Nakagawa S.
Published: April 2011

To reduce medium noise inherent in a perpendicular magnetic recording tape, which is deposited by facing targets sputtering, we have examined an epitaxial double-layered structure consisting of a soft magnetic underlayer (SUL), bcc-FeCoB/fcc-NiFe/Si/bcc-FeCoB, on a 4.5 μm para-aromatic polyamide (aramid) film. An epitaxial soft magnetic bilayer reduces broadband noise by 5.6 dB at 337 kilo fluxchanges per inch (kfci) compared to a single SUL medium (Tape S). This is due to the reduction in the low-frequency noise, which originates from the domain walls of the SUL. Improvement of the crystal orientation of the magnetic layer hcp-CoPtCr–SiO2 and the intermediate layer hcp-Ru by inserting a fcc-NiFe spacer in laminated SULs extends the roll-off curve toward high linear density. When each SUL layer of the bilayer was made thinner, from 25 nm (Tape D2) to 10 nm (Tape D1), the medium noise decreased, improving the signal-to-noise ratio by 8.6 dB at 337 kfci compared to Tape S. In a high resolution playback test of Tape D1, an areal density of 45.0 gigabits per square inch (Gb/in.2) was confirmed. Achieved areal density means the capability of an over-50 terabyte (TB) capacity for a typical linear-formatted data cartridge.
Tunable magnetoresistance devices based on multiferroic heterostructures
Authors: Liu Ming , Obi Ogheneyunume , Lou Jing , Li Shandong , Xing Xing , Yang Guomin , Sun Nian X.
Published: April 2011

Surface-effect induced strong magnetoelectric (ME) coupling was investigated in ultrathin Ni80Fe20/PZN-PT (lead zinc niobate-lead titanate) multiferroic heterostructures. Giant electric field (E-field) tuning of the magnetic anisotropy, ferromagnetic resonance field, coercive field and anisotropic magnetoresistance were demonstrated through strain mediated ME coupling in 10 nm thick Ni80Fe20/PZN-PT multiferroic heterostructures. E-field dynamic modulation of magnetoresistance was also displayed. These provide great opportunities for electrostatic tunable MR devices.
Microwave assisted magnetization switching in Co/Pt multilayer
Authors: Okamoto S. , Kikuchi N. , Kitakami O. , Shimatsu T. , Aoi H.
Published: April 2011

In this study, we have experimentally investigated the microwave assisted magnetization by switching (MAS) on the microstructured Co/Pt multilayer. The sample exhibits the typical magnetization curve peculiar to perpendicular anisotropy films, that is, a steep reversal initiated by nucleation of a reversed domain followed by its subsequent gradual expansion by the domain wall displacement. By applying microwaves with the frequency of GHz order, the nucleation field Hn is significantly reduced at three frequencies. Taking into account the effective anisotropy field of our sample, the first dip of Hn at the lowest frequency probably corresponds to the Kittel mode excitation, and the other two dips at higher frequencies correspond to unidentified excitation modes other than the Kittel mode. Among them, the last dip of Hn at the highest frequency reaches about 1/3 of that without microwave application. These results suggest the existence of more effective excitation modes for MAS than the Kittel mode.
Improved magnetostriction of Fe72Ga28 boron doped alloys
Authors: Bormio-Nunes Cristina , Teodoro dos Santos Claudio , Fernandes Leandro Inaê , Sato Turtelli Reiko , Grössinger Roland , Atif Muhammad
Published: April 2011

In order to investigate the effect of boron additions in the magnetostrictive behavior of Fe72Ga28 alloy, this alloy was doped with 0.5, 1.0, 1.5 and 2.0 at.% of boron. The results have shown that boron additions of 0.5 and 1.0% improve significantly the magnetostriction, the values being about two-fold higher compared to the undoped alloy. Microstructural evaluations suggest that boron additions suppress partially the D03 phase ordering, retaining the α-phase. Furthermore, the increase of lattice parameters of the α and D03 phases indicates that boron enters interstitially in the cubic lattice of these phases. Both effects are considered to be responsible for the increased magnetostriction observed in the (Fe0.72Ga0.28)99.5B0.5 and Fe0.72Ga0.28)99.0B1.0 alloys.
Structural and magnetic properties of bulk MnBi permanent magnets
Authors: Zhang D. T. , Cao S. , Yue M. , Liu W. Q. , Zhang J. X. , Qiang Y.
Published: April 2011

Structural and magnetic properties of bulk nanostructural Mn100−xBix (x = 40, 45, 52) permanent magnets prepared by spark plasma sintering technique were studied. The effect of the Mn/Bi ratio on the MnBi low temperature phase (LTP) formation and its magnetic properties were investigated. An increase of the bismuth amount in the magnets leads to better formation of LTP, resulting in the improvement of both magnetization (Ms) and remanence (Mr), but decreasing the coercivity (Hc) of the magnets. At room temperature, Ms increases from 27.87 emu/g for Mn60Bi40 to 45.31 emu/g for Mn48Bi52, whereas Hc decreases from 12 to 7.9 kOe. The microstructure of Mn48Bi52 magnet is composed of fine and uniform grains with an average size of 140 nm as shown in the TEM image. The Mn48Bi52 magnet shows a high Hc of 19 kOe at 423 K, indicating a strong positive temperature coefficient of coercivity for the MnBi magnet.
Tailoring the shape of flux guide reader for ultrahigh density magnetic recording
Authors: Lua Sunny Yan Hwee , Wang Jacob Chenchen , Han Guchang
Published: April 2011

We report on a study of shape effect on the flux guide (FG) reader output at an ultrahigh recording density, using micromagnetic simulations. A FG with a sharp, protruding reading edge is ineffective in magnetization reversal but is less susceptible to adjacent track interference. By using an FG with an acute, tapered angle and an elongated spade shape, a reversible magnetization can be achieved and the amplitude of the readback signal can be improved. The findings indicate that the shape of the FG can be tailored for effective control of the magnetoresistance signal for ultrahigh data storage density in hard disk drives.
Low frequency noise characteristics of submicron magnetic tunnel junctions
Authors: Zhong B. , Chen Y. , Garzon S. , Crawford T. M. , Webb R. A.
Published: April 2011

We report that low frequency (up to 200 kHz) noise spectra of magnetic tunnel junctions with areas 10-10 cm2 at 10 K deviate significantly from the typical 1/f behavior found in large area junctions at room temperature. In most cases, a Lorentzian-like shape with characteristic time between 0.1 and 10 ms is observed, which indicates only a small number of fluctuators contribute to the measured noise. By investigating the dependence of noise on both the magnitude and orientation of an applied magnetic field, we find that magnetization fluctuations in both free and reference layers are the main sources of noise in these devices. At small fields, where the noise from the free layer is dominant, a linear relation between the measured noise and angular magnetoresistance susceptibility can be established.
Experimental investigation of the flow in the near-field of a cross-shaped orifice jet
Authors: El Hassan Mouhammad , Meslem Amina , Abed-Meraim Kamel
Published: April 2011

The flow in the near-field of a cross-shaped orifice jet is investigated experimentally in the present study. The three components of the velocity field are obtained at different longitudinal locations using time-resolved stereoscopic particle-image velocimetry measurements. The mean and the instantaneous entrainment rates are calculated to study the entrainment mechanism. The distribution of momentum thicknesses is also inspected in the region of the axis switching. It is found that both the instantaneous entrainment rate and the net volume flux are strongly dependent on the vortical structures present in the flow and particularly at different parts of the Kelvin–Helmholtz vortex ring. Hence, different phases of the flow are investigated in the region of the axis switching. The contribution of the turbulent normal and shear stresses to the streamwise vorticity generation is also studied in the near-field of the cross jet. The momentum flux and its streamwise evolution are obtained from the mean velocity field. The contribution of different turbulent intensities to the momentum flux is given. The proper orthogonal decomposition (POD) is then applied to show the streamwise evolution of energy content of the most energetic POD modes.
Analytical models for the shear modulus of α-Pu and Ga-stabilized δ-Pu versus temperature and pressure from measurements
Authors: Nadal Marie-Hélène , Bourgeois Ludivine , Migliori Albert
Published: April 2011

From measurements we model some constitutive relations of pure plutonium and Ga-stabilized δ-plutonium alloy (Pu-2.3 at.%Ga), focusing on the shear modulus G versus temperature T (T ∈ [300; 750] K) and pressure P (P ∈ [0; 1] GPa). G(T) or G(P) are computed from the density-corrected elastic-waves velocities for each crystallographic phase. The models developed here in this temperature and pressure range provide useful analytical forms in contrast to the discrete values of the measurements. Because it is reasonable to expect that the bulk moduli of pure and Ga-stabilized δ-Pu also agree where they exist at the same temperatures, these models are applicable to comparisons with ab-initio calculations (which are essentially zero-temperature calculations) for pure Pu. A model for G(P,T) is also provided for use in elasto-plastic models implemented in hydrodynamic codes based on measurements of G(T) up to 750 K and G(P) up to 1 GPa. The model for G(P,T) of Pu-2.3 at.%Ga accounts for the presence of α’ under pressure. The G(P,T) model, a continuous function from solid to liquid, uses the phase transition temperatures and the melting temperature to make it more than a simple curve fit.
Structural, electrical, and magnetic properties of polycrystalline Fe3−xPtxO4 (0 ≤ x ≤ 0.10) films
Authors: Cheng Y. H. , Li L. Y. , Wang W. H. , Luo X. G. , Liu Hui , Zheng R. K.
Published: April 2011

Polycrystalline Fe3-xPtxO4 films have been prepared by cosputtering at room-temperature. The composition, magnetization and Hall effect measurements indicate that Pt ions have been doped at B-sites. The resistivity is dominated by fluctuation-induced tunneling and decreases with increasing x. The absolute magnetoresistance at room-temperature is above 7% for x≤0.07. The carrier concentration is lower than that of the single-crystal and epitaxial films. A scaling relation of σxy∝σxxn between the Hall and longitudinal conductivities is obtained for all samples, which fits well with the recent developed universal scaling theory. The decreasing trend of the exponent n from 1.72 to 1.57 with increasing x could be qualitatively ascribed to the influence of the Pt2+ ions on the magnetic scattering center concentration of the B-sites Fe2+ ions. These findings make the Fe3-xPtxO4 film a useful candidate for spintronic or extraordinary Hall effect devices applications.
Ultracompact surface-plasmon-polariton splitter based on modulations of quasicylindrical waves to the total field
Authors: Chen Jianjun , Li Zhi , Yue Song , Gong Qihuang
Published: April 2011

By coating a metal with a finite-thickness dielectric film, evident differences in the wave-vector magnitude between surface plasmon polaritons (SPPs) and quasicylindrical waves (quasi-CWs) emerge. This brings modulation patterns to the total field on the metal surface near the electromagnetic source. Based on such an effect, an ultracompact SPP splitter with a lateral dimension of only 800 nm is experimentally demonstrated at wavelengths of 740 nm and 832 nm in a dielectric-film-coated asymmetric single nanoslit. These results imply that the additional modulation of quasi-CWs to the total field provide new possibilities for the design of ultracompact plasmonic devices.
Binding of hydrogen on benzene, coronene, and graphene from quantum Monte Carlo calculations
Authors: Ma Jie , Michaelides Angelos , Alfè Dario
Published: April 2011

Quantum Monte Carlo calculations with the diffusion Monte Carlo (DMC) method have been used to compute the binding energy curves of hydrogen on benzene, coronene, and graphene. The DMC results on benzene agree with both Møller–Plessett second order perturbation theory (MP2) and coupled cluster with singles, doubles, and perturbative triples [CCSD(T)] calculations, giving an adsorption energy of ∼25 meV. For coronene, DMC agrees well with MP2, giving an adsorption energy of ∼40 meV. For physisorbed hydrogen on graphene, DMC predicts a very small adsorption energy of only 5 ± 5 meV. Density functional theory (DFT) calculations with various exchange-correlation functionals, including van der Waals corrected functionals, predict a wide range of binding energies on all three systems. The present DMC results are a step toward filling the gap in accurate benchmark data on weakly bound systems. These results can help us to understand the performance of current DFT based methods, and may aid in the development of improved approaches.
Micro-power generator supplying source for integrated circuit chip based on Pb(Sn,Zr,Ti)O3 ferroelectric ceramic
Authors: Zhang Zhenhai , Cui Zhanzhong , Yan Jinglong , Li Kejie
Published: April 2011

We have demonstrated both experimentally and theoretically that a tin-modified and niobium-modified lead zirconate titanate (Pb(Sn,Zr,Ti)O3) ferroelectric generator system can function as a micro-power supplying source for integrated circuit (IC) chip of separate nonelectric impulse input shock tube digital delay detonator. The ferroelectric ceramic phase transition under transverse shock wave compression can charge an external storage capacitor. The ferroelectric ceramic micro-pulsed-power system is capable of generating low output voltage pulses with an amplitude of 54.2 V and with transferred energy of 1.73 mJ, ultimately supplying an IC chip with micro-power. This work presents the methodology for theoretical analysis and experimental operation of the ferroelectric generator. Theoretical calculations are conducted based on circuit analysis law and principles of dynamic high pressure and shock wave physics. The experimental results were in good agreement with the theoretical analysis.
A micro-optical modulation spectroscopy technique for local strain measurement
Authors: Chouaib H. , Murtagh M. E. , Kelly P. V.
Published: April 2011

We provide a high throughput method of performing optical modulation spectroscopy, such as photoreflectance or other spectroscopy techniques which include photoluminescence on a micrometric resolution scale of the order of 10 μm. The spectroscopic technique is designed for strain induced by process in silicon wafers. The optical system is optimized using a polarizing beamsplitter in conjunction with a single Fresnel rhomb for the provision of an optimum separation of the reflected probe beam with minimal optical losses. In addition, a rapid detection system is used that allows the spectrum to be acquired within few seconds.
Unidirectional, electrotactic-response valve for Caenorhabditis elegans in microfluidic devices
Authors: Carr John A. , Lycke Roy , Parashar Archana , Pandey Santosh
Published: April 2011

We report a nematode electrotactic-response valve (NERV) to control the locomotion of Caenorhabditis elegans (C. elegans) in microfluidic devices. This nonmechanical, unidirectional valve is based on creating a confined region of lateral electric field that is switchable and reversible. We observed that C. elegans do not prefer to pass through this region if the field lines are incident to its forward movement. Upon reaching the boundary of the NERV, the incident worms partially penetrate the field region, pull back, and turn around. The NERV is tested on three C. elegans mutants: wild-type (N2), lev-8, and acr-16.
Double-sensor method for detection of oscillating electric field
Authors: Ohkuma Yasunori , Ikeyama Taeko , Nogi Yasuyuki
Published: April 2011

An electric-field sensor consisting of thin copper plates is designed to measure an oscillating electric field produced by charge separations on a plasma column. The sensor installed in a vacuum region around plasma detects charges induced by the electric field on the copper plates. The value of the induced charges depends not only on the strength of the electric field, but also on the design of the sensor. To obtain the correct strength of the electric field, a correction factor arising from the design of the sensor must be known. The factor is calculated numerically using Laplace's equation and compared with a value measured using a uniform electric field in the frequency range of 10–500 kHz. When an external circuit is connected to the sensor to measure the induced charges, the electric field around the sensor is disturbed. Therefore, a double-sensor method for excluding a disturbed component in the measured electric field is proposed. The reliability of the double-sensor method is confirmed by measuring dipole-like and quadrupole-like electric fields.
Existence of optical phonons in the room temperature ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate
Authors: Burba Christopher M. , Frech Roger
Published: April 2011

The technologically important properties of room temperature ionic liquids (RTILs) are fundamentally linked to the ion–ion interactions present among the constituent ions. These ion–ion interactions in one RTIL (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, [C2mim]CF3SO3) are characterized with transmission FTIR spectroscopy and polarized attenuated total reflection (ATR) FTIR spectroscopy. A quasilattice model is determined to be the best framework for understanding the ionic interactions. A novel spectroscopic approach is proposed to characterize the degree of order that is present in the quasilattice by comparing the dipole moment derivative calculated from two independent spectroscopic measurements: (1) the TO–LO splitting of a vibrational mode using dipolar coupling theory and (2) the optical constants of the material derived from polarized ATR experiments. In principle, dipole moment derivatives calculated from dipolar coupling theory should be similar to those calculated from the optical constants if the quasilattice of the RTIL is highly structured. However, a significant disparity for the two calculations is noted for [C2mim]CF3SO3, indicating that the quasilattice of [C2mim]CF3SO3 is somewhat disorganized. The potential ability to spectroscopically characterize the structure of the quasilattice, which governs the long-range ion–ion interactions in a RTIL, is a major step forward in understanding the interrelationship between the molecular-level interactions among the constituent ions of an ionic liquid and the important physical properties of the RTIL.
The operations of quantum logic gates with pure and mixed initial states
Authors: Chen Jun-Liang , Li Che-Ming , Hwang Chi-Chuan , Ho Yi-Hui
Published: April 2011

The implementations of quantum logic gates realized by the rovibrational states of a C12O16 molecule in the X(1Σ+) electronic ground state are investigated. Optimal laser fields are obtained by using the modified multitarget optimal theory (MTOCT) which combines the maxima of the cost functional and the fidelity for state and quantum process. The projection operator technique together with modified MTOCT is used to get optimal laser fields. If initial states of the quantum gate are pure states, states at target time approach well to ideal target states. However, if the initial states are mixed states, the target states do not approach well to ideal ones. The process fidelity is introduced to investigate the reliability of the quantum gate operation driven by the optimal laser field. We found that the quantum gates operate reliably whether the initial states are pure or mixed.
Si/SiGe quantum dot with superconducting single-electron transistor charge sensor
Authors: Yuan Mingyun , Pan Feng , Yang Zhen , Gilheart T. J. , Chen Fei , Savage D. E. , Lagally M. G. , Eriksson M. A. , Rimberg A. J.
Published: April 2011

We report a robust process for fabrication of surface-gated Si/SiGe quantum dots (QDs) with an integrated superconducting single-electron transistor (SSET) charge sensor. A combination of a deep mesa etch and AlOx backfill is used to reduce gate leakage. After the leakage current is suppressed, Coulomb oscillations of the QD and the current-voltage characteristics of the SSET are observed at a temperature of 0.3 K. Coupling of the SSET to the QD is confirmed by using the SSET to perform sensing of the QD charge state.
Renormalization of the frozen Gaussian approximation to the quantum propagator
Authors: Tatchen Jörg , Pollak Eli , Tao Guohua , Miller William H.
Published: April 2011

The frozen Gaussian approximation to the quantum propagator may be a viable method for obtaining “on the fly” quantum dynamical information on systems with many degrees of freedom. However, it has two severe limitations, it rapidly loses normalization and one needs to know the Gaussian averaged potential, hence it is not a purely local theory in the force field. These limitations are in principle remedied by using the Herman–Kluk (HK) form for the semiclassical propagator. The HK propagator approximately conserves unitarity for relatively long times and depends only locally on the bare potential and its second derivatives. However, the HK propagator involves a much more expensive computation due to the need for evaluating the monodromy matrix elements. In this paper, we (a) derive a new formula for the normalization integral based on a prefactor free HK propagator which is amenable to “on the fly” computations; (b) show that a frozen Gaussian version of the normalization integral is not readily computable “on the fly”; (c) provide a new insight into how the HK prefactor leads to approximate unitarity; and (d) how one may construct a prefactor free approximation which combines the advantages of the frozen Gaussian and the HK propagators. The theoretical developments are backed by numerical examples on a Morse oscillator and a quartic double well potential.
Photocurrent spectroscopy of single CdS nanosheets: Valence band structure and two photon absorption
Authors: Kumar P. , Wade A. , Smith L. M. , Jackson H. E. , Yarrison-Rice J. M. , Choi Y.-J. , Park J.-G.
Published: April 2011

Photocurrent spectroscopy has been carried out on single CdS nanosheet devices in the metal-semiconductor-metal configuration with both Schottky and Ohmic contacts. Spatial imaging of the photocurrent shows that the photosensitive regions are localized at the reverse biased contact for Schottky type contacts and uniformly distributed throughout the nanosheet for Ohmic contacts. Photocurrent spectra show excitonic resonances at low temperatures corresponding to the A, B, C hole bands. Subband gap pulsed laser excitation reveals two-photon absorption dominated photocurrents consistent with a nonlinear coefficient of β=2 cm/GW for these nanosheet devices.
Giant mesoscopic photoconductance fluctuations in Ge/Si quantum dot system
Authors: Stepina N. P. , Koptev E. S. , Dvurechenskii A. V. , Nikiforov A. I. , Gerharz J. , Moers J. , Gruetzmacher D.
Published: April 2011

We studied the impact of weak photon flux on the electron transport in strongly localized quantum dot system. Exploring devices with narrow transport channels lead to the observation of giant fluctuations of the photoconductance, which is attributed to the strong dependence of hopping current on the filling of dots by holes. This phenomenon has the potential to detect a single photoexcited carrier for a wide range of wavelength. In our experiments, single-photon mode operation is indicated by the linear dependence of the frequency of photoinduced fluctuations on the light intensity and the steplike response of conductance on the pulse excitation.
A layered microchip conductance detector with through-layer access to detection fields and high sensitivity to dielectric constant
Authors: Suganuma Y. , Dhirani A.-A.
Published: April 2011

The present study explores a novel apertured microchip conductance detector (AMCD) that is sensitive to dielectric constant. Fashioned on silicon oxide/silicon using optical microlithography, the detector has novel parallel-plate geometry with a top mesh electrode, a middle apertured insulator, and a bottom conducting electrode. This monolithic apertured architecture is planar and may be provided with a thin insulator layer enabling large capacitances, while the top mesh electrode and middle apertured-insulator enable access to regions of the capacitor where electric fields are strong. Hence, the detector is sensitive yet mechanically robust. To test its response, the AMCD was immersed in various solvents, namely water, methanol, acetonitrile, and hexanes. Its response was found to vary in proportion to the solvents’ respective dielectric constants. The AMCD was also able to distinguish quantitatively the presence of various molecules in solution, including molecules with chromophores [such as acetylsalicylic acid (ASA)] in methanol and those without chrompohores [such as polyethylene glycol 200 Daltons (PEG200)] in methanol or water. The universal nature of dielectric constant and the microchip detector's sensitivity point to a wide range of potential applications.
Jastrow correlated and quantum Monte Carlo calculations for the low-lying states of the carbon atom
Authors: Maldonado P. , Sarsa A. , Buendía E. , Gálvez F. J.
Published: April 2011

Different computational methods are employed to calculate excitation energies of the carbon atom. Explicitly correlated wave functions have been obtained in a Variational Monte Carlo calculation. Fixed node Diffusion Monte Carlo calculations for the lowest energy excited states of a given symmetry are reported. A systematic and quantitative analysis of the performance of the different schemes in the calculation of the excitation energy of up to 27 excited states of the carbon atom is carried out. The quality of the different methods have been studied in terms of the deviation with respect to the experimental excitation energies. A good agreement with the experimental values has been reached.
Validation of three new measure-correlate-predict models for the long-term prospection of the wind resource
Authors: Romo Perea Alejandro , Amezcua Javier , Probst Oliver
Published: April 2011

The estimation of the long-term wind resource at a prospective site based on a relatively short on-site measurement campaign is an indispensable task in the development of a commercial wind farm. The typical industry approach is based on the measure-correlate-predict (MCP) method where a relational model between the site wind velocity data and the data obtained from a suitable reference site is built from concurrent records. In a subsequent step, a long-term prediction for the prospective site is obtained from a combination of the relational model and the historic reference data. In the present paper, a systematic study is presented where three new MCP models, together with two published reference models (a simple linear regression and the variance ratio method), have been evaluated based on concurrent synthetic wind speed time series for two sites, simulating the prospective and the reference site. The synthetic method has the advantage of generating time series with the desired statistical properties, including Weibull scale and shape factors, required to evaluate the five methods under all plausible conditions. In this work, first a systematic discussion of the statistical fundamentals behind MCP methods is provided and three new models, one based on a nonlinear regression and two (termed kernel methods) derived from the use of conditional probability density functions, are proposed. All models are evaluated by using five metrics under a wide range of values of the correlation coefficient, the Weibull scale, and the Weibull shape factor. Only one of all models, a kernel method based on bivariate Weibull probability functions, is capable of accurately predicting all performance metrics studied.
High-temperature thermoelectric properties of nanostructured Ca3Co4O9 thin films
Authors: Kang Min-Gyu , Cho Kwang-Hwan , Oh Seung-Min , Kim Jin-Sang , Kang Chong-Yun , Nahm Sahn , Yoon Seok-Jin
Published: April 2011

We prepared nanostructured Ca3Co4O9 (CCO) thin films by promoting localized epitaxial growth on polycrystalline Al2O3 substrates. The thermoelectric properties of the CCO films were studied in the temperature range 300 to 1023 K. We confirmed that localized epitaxial growth occurred on the seed grains that dominate the (006) plane. The nanostructured CCO thin films were found to have a maximum Seebeck coefficient of 206 μV/K and a power factor (at 920 K) of 0.514 mW/mK2. Moreover, the presence of nanostructure was found to reduce the thermal conductivity, and thus, should enhance the overall performance of CCO films in thermoelectric devices.
UV nanoimprint lithography for the realization of large-area ordered SiGe/Si(001) island arrays
Authors: Lausecker E. , Brehm M. , Grydlik M. , Hackl F. , Bergmair I. , Mühlberger M. , Fromherz T. , Schäffler F. , Bauer G.
Published: April 2011

We use UV nanoimprint lithography for the pit-patterning of silicon substrates. Ordered silicon-germanium islands are grown inside these pits by molecular-beam epitaxy on arrays of 3×3 mm2 and characterized by atomic force microscopy (AFM) and photoluminescence (PL) measurements. AFM-based statistics reveals an extremely uniform size distribution of the islands in the patterned areas. These results are confirmed by very narrow and uniform PL peaks recorded at various positions across the patterned arrays.
Manifestation of altruism: Perceptions among counselling students in the United Kingdom
Authors: Swank Jacqueline M. , Robinson Mike E.H. , Ohrt Jonathan H.
Published: April 2011

Aims: The purpose of this study was to examine the applicability of a proposed model of the development of altruism, or unselfish caring for others, as perceived by counselling students in the UK. Method: Semi‐structured interviews were conducted with eight counsellors‐in‐training. The data analysis involved open coding, axial coding, and the development of a coding paradigm. Findings: The findings address the four factors (biological, cognitive, social learning, and religiosity/spirituality) proposed in the model. Additional themes included: (a) community development and sustainability, (b) altruism across the lifespan, and (c) the counselling profession. Implications: The findings suggest a relationship between altruism and counsellor success. This supports the integration of altruism within the counselling curriculum, as it relates to the British Association for Counselling and Psychotherapy (BACP) Ethical Framework (2010). Furthermore, the findings support future research focused on altruism.
Peter Walter: Investigating how the ER handles secretory proteins
Authors: Sedwick Caitlin
Published: April 2011

Walter studies how proteins are targeted to the endoplasmic reticulum and how cells deal with ER stress.
A presynaptic endosomal trafficking pathway controls synaptic growth signaling
Authors: Rodal Avital A. , Blunk Aline D. , Akbergenova Yulia , Jorquera Ramon A. , Buhl Lauren K. , Littleton J. Troy
Published: April 2011

Structural remodeling of synapses in response to growth signals leads to long-lasting alterations in neuronal function in many systems. Synaptic growth factor receptors alter their signaling properties during transit through the endocytic pathway, but the mechanisms controlling cargo traffic between endocytic compartments remain unclear. Nwk (Nervous Wreck) is a presynaptic F-BAR/SH3 protein that regulates synaptic growth signaling in Drosophila melanogaster. In this paper, we show that Nwk acts through a physical interaction with sorting nexin 16 (SNX16). SNX16 promotes synaptic growth signaling by activated bone morphogenic protein receptors, and live imaging in neurons reveals that SNX16-positive early endosomes undergo transient interactions with Nwk-containing recycling endosomes. We identify an alternative signal termination pathway in the absence of Snx16 that is controlled by endosomal sorting complex required for transport (ESCRT)–mediated internalization of receptors into the endosomal lumen. Our results define a presynaptic trafficking pathway mediated by SNX16, NWK, and the ESCRT complex that functions to control synaptic growth signaling at the interface between endosomal compartments.
Legendrian framings for two-bridge links
Authors: Baader Sebastian , Ishikawa Masaharu
Published: April 2011

We define the Thurston-Bennequin polytope of a two-component link as the convex hull of all pairs of integers that arise as framings of a Legendrian representative. The main result of this paper is a description of the Thurston-Bennequin polytope for two-bridge links. As an application, we construct non-quasipositive surfaces in

R

3

\mathbb {R}^3

all of whose sub-annuli are quasipositive.