bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term effect of morphine administration in young rats on the analgesic opioid response in adult life
Authors: Rozisky Joanna Ripoll , Dantas Giovana , Adachi Lauren Spezia , Alves Viviane Soares , Ferreira Maria Beatriz Cardoso , Sarkis João José Freitas , Torres Iraci Lucena Da Silva
Published: May 2008

Neonates, infants and children are often exposed to pain from invasive procedures during intensive care and during the post‐operative period. Opioid anesthesia and post‐operative opioid analgesia have been used in infants and result in clinical benefits. The objectives of this study were to verify the effect of repeated 5 μg morphine administration (subcutaneous), once a day for 7 days in 8‐day‐old rats, at P8 until P14. To verify the long‐term effect of morphine, the animals were submitted to a second exposure of 5 mg/kg (intraperitoneal) of morphine at P80 until P86. Animals that received morphine for 7 days, at P14 did not develop tolerance, however at P80, rats demonstrated greater morphine analgesia. At P86, after 7 days of morphine administration, animals showed classical tolerance. These findings may have important implications for the human neonate, suggesting a possible explanation for the differences in the requirements of morphine observed in the youngest patients.
Current Perspectives on Stability of Protein Drug Products during Formulation, Fill and Finish Operations
Authors: Rathore Nitin , Rajan Rahul S.
Published: May 2008

Commercialization of protein‐based therapeutics is a challenging task in part due to the difficulties in maintaining protein solutions safe and efficacious throughout the drug product development process, storage, transportation and patient administration. Bulk drug substance goes through a series of formulation, fill and finish operations to provide the final dosage form in the desired formulation and container or delivery device. Different process parameters during each of these operations can affect the purity, activity and efficacy of the final product. Common protein degradation pathways and the various physical and chemical factors that can induce such reactions have been extensively studied for years. This review presents an overview of the various formulation‐fill‐finish operations with a focus on processing steps and conditions that can impact product quality. Various manufacturing operations including bulk freeze‐thaw, formulation, filtration, filling, lyophilization, inspection, labeling, packaging, storage, transport and delivery have been reviewed. The article highlights our present day understanding of protein instability issues during biopharmaceutical manufacturing and provides guidance on process considerations that can help alleviate these concerns.
Antibacterial Colorants: Characterization of Prodiginines and Their Applications on Textile Materials
Authors: Alihosseini Farzaneh , Ju Kou‐San , Lango Jozsef , Hammock Bruce D. , Sun Gang
Published: May 2008

A strain of Vibriosp. isolated from marine sediments produced large quantities of bright red pigments that could be used to dye many fibers including wool, nylon, acrylics, and silk. Characterization of the pigments by electrospray ionization mass spectrometry (ESI‐MS) and nuclear magnetic resonance (NMR) revealed three prodiginine‐like structures with nonpolar characteristics and low molecular mass. UV‐visible spectra of the major constituent in methanol solution showed absorbance at λmax 530 nm wavelength. The accurate mass result showed that the main isolated product has a molecular mass of m/ z 323.1997. Further analysis using mass fragmentation (MS/MS), 1H NMR, COSY, HMQC NMR and DEPT confirmed the detailed structure of the pigment with an elementary composition of C20H25N3O. Fabrics dyed with the microbial prodiginines demonstrated antibacterial activity.
Electron impact ionization of size selected hydrogen clusters (H2)N: Ion fragment and neutral size distributions
Authors: Kornilov Oleg , Toennies J. Peter
Published: May 2008

Clusters consisting of normal H2 molecules, produced in a free jet expansion, are size selected by diffraction from a transmission nanograting prior to electron impact ionization. For each neutral cluster (H2)N (N=2–40), the relative intensities of the ion fragments Hn+ are measured with a mass spectrometer. H3+ is found to be the most abundant fragment up to N=17. With a further increase in N, the abundances of H3+, H5+, H7+, and H9+ first increase and, after passing through a maximum, approach each other. At N=40, they are about the same and more than a factor of 2 and 3 larger than for H11+ and H13+, respectively. For a given neutral cluster size, the intensities of the ion fragments follow a Poisson distribution. The fragmentation probabilities are used to determine the neutral cluster size distribution produced in the expansion at a source temperature of 30.1K and a source pressure of 1.50bar. The distribution shows no clear evidence of a magic number N=13 as predicted by theory and found in experiments with pure para-H2 clusters. The ion fragment distributions are also used to extract information on the internal energy distribution of the H3+ ions produced in the reaction H2++H2→H3++H, which is initiated upon ionization of the cluster. The internal energy is assumed to be rapidly equilibrated and to determine the number of molecules subsequently evaporated. The internal energy distribution found in this way is in good agreement with data obtained in an earlier independent merged beam scattering experiment.
Low-energy electron diffraction and induced damage in hydrated DNA
Authors: Orlando Thomas M. , Oh Doogie , Chen Yanfeng , Aleksandrov Alexandr B.
Published: May 2008

Elastic scattering of 5–30eV electrons within the B-DNA 5′-CCGGCGCCGG-3′ and A-DNA 5′-CGCGAATTCGCG-3′ DNA sequences is calculated using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to a featureless amplitude buildup of elastically scattered electrons on the sugar and phosphate groups for all energies between 5 and 30eV. However, some constructive interference features arising from diffraction are revealed when examining the structural waters within the major groove. These appear at 5–10, 12–18, and 22–28eV for the B-DNA target and at 7–11, 12–18, and 18–25eV for the A-DNA target. Although the diffraction depends on the base-pair sequence, the energy dependent elastic scattering features are primarily associated with the structural water molecules localized within 8–10Å spheres surrounding the bases and/or the sugar-phosphate backbone. The electron density buildup occurs in energy regimes associated with dissociative electron attachment resonances, direct electronic excitation, and dissociative ionization. Since diffraction intensity can be localized on structural water, compound H2O:DNA states may contribute to energy dependent low-energy electron induced single and double strand breaks.
The evolution of Kirchhoff elliptic vortices
Authors: Mitchell T. B. , Rossi L. F.
Published: May 2008

A Kirchhoff elliptic vortex is a two-dimensional elliptical region of uniform vorticity embedded in an inviscid, incompressible, and irrotational fluid. By using analytic theory and contour dynamics simulations, we describe the evolution of perturbed Kirchhoff vortices by decomposing solutions into constituent linear eigenmodes. With small amplitude perturbations, we find excellent agreement between the short time dynamics and the predictions of linear analytic theory. Elliptical vortices must have aspect ratios less than a∕b=3 to be completely stable. At late times, unstable perturbations evolve to states consisting of filaments surrounding and connecting one or more separate vortex core regions. Even modes have two different evolution paths accessible to them, dependent on the initial phase. Ellipses can first fission into more than one separate region when a∕b=6.046, from the negative branch m=4 mode. Increasing the perturbation amplitude can result in nonlinear instability, while the perturbation is still small relative to any vortex dimension. For the lowest m modes, we quantify the transition from linear to nonlinear behavior.
Time dependent quantum dynamics study of the Ne+H2+(v=–4)→NeH++H proton transfer reaction
Authors: Mayneris Jordi , Sierra José Daniel , González Miguel
Published: May 2008

The Ne+H2+→NeH++H proton transfer reaction was studied using the time dependent real wave packet quantum dynamics method at the helicity decoupling level, considering the H2+ molecular ion in the (v=0–4, j=0) vibrorotational states and a wide collision energy interval. The calculated reaction probabilities and reaction cross sections were in a rather good agreement with reanalyzed previous exact quantum dynamics results, where a much smaller collision energy interval was considered. Also, a quite good agreement with experimental data was found. These results suggested the adequacy of the approach used here to describe this and related systems.
Does drop size affect the mechanism of viscoelastic drop breakup?
Authors: Li Huaping , Sundararaj Uttandaraman
Published: May 2008

We studied the breakup of viscoelastic drops in Newtonian liquid matrices undergoing simple shear flow. The coexistence of different breakup modes was observed. The drop size determines, to a great extent, the type of drop breakup mechanism and the critical point when the mechanism changes. Small drops break along the vorticity direction, which is the direction perpendicular to the flow direction and the velocity gradient direction, whereas large drops break in the flow direction. The change in mechanism abruptly occurs as the drop size reduces. There is a big jump in the critical shear rate when the mechanism changes from breakup in the flow direction to breakup in the vorticity direction.
Self-assembled monolayer modified ZnO/metal bilayer cathodes for polymer/fullerene bulk-heterojunction solar cells
Authors: Yip Hin-Lap , Hau Steven K. , Baek Nam Seob , Jen Alex K.-Y.
Published: May 2008

A simple method was developed to tune the interface of cathode in polymer solar cells by inserting a layer of ZnO/self-assembled monolayer (SAM) between a poly(3-hexylthiophene): [6,6]-phenyl-C61 butyric acid methyl ester bulk-heterojunction film and a metal cathode. We found that the device performance could be significantly altered depending on the dipole direction and chemical bonding between the SAM and metals. With appropriate choice of SAMs, devices show dramatically improved efficiencies and even high work-function metals such as Ag and Au could be used as cathodes. This finding provides an efficient method for interface engineering in organic-based optoelectronic devices.
Band gap narrowing and radiative efficiency of silicon doped GaN
Authors: Schenk H. P. D. , Borenstain S. I. , Berezin A. , Schön A. , Cheifetz E. , Khatsevich S. , Rich D. H.
Published: May 2008

Radiative efficiency, band gap narrowing, and band filling are studied in Si-doped GaN films as a function of carrier concentration (n), using room and low temperature cathodoluminescence (CL). Using the Kane model, a band gap narrowing ΔEg of −(3.6±0.6)×10−8 and −(2.6±0.6)×10−8n1/3 eVn1/3 is obtained for epitaxially strained and relaxed material, respectively. Band-edge CL time response and absolute external photon yield are measured. The internal radiation efficiency is deduced. Its monotonic increase as n increases is explained by the increase in the spontaneous radiative rate with a radiative free carrier band-to-band recombination coefficient B=(1.2±0.3)×10−11 cm3 s−1.
A hydrogen storage layer on the surface of silicon nitride films
Authors: Liu Ziyuan , Ito Shuu , Wilde Markus , Fukutani Katsuyuki , Hirozawa Ichiro , Koganezawa Tomoyuki
Published: May 2008

Composition, layer structure, and H-retaining stability of 980°C N2-annealed silicon nitride-oxide (ON) stacks were analyzed using high resolution rutherford backscattering, synchrotron x-ray specular reflectometry, and nuclear reaction analysis. The formation of a Si2N2O layer in the near-surface part of N2-annealed nitride films was discovered. The Si2N2O layer can store hydrogen species that are resistant against energetic electron damage due to their reduced diffusion mobility. Although degrading in air, the Si2N2O layer thus provides reliable hydrogen species, which are desirable in the integrated circuit processing of silicon transistors and silicon ONO trap memories.
Vibronic nature of hafnium oxide/silicon interface states investigated by capacitance frequency spectroscopy
Authors: Engström O. , Raeissi B. , Piscator J.
Published: May 2008

Using a method based on the frequency dependence of capacitance, cross sections for electron capture into energy states at the interlayer/silicon interface have been investigated for HfO2 that is deposited on silicon by reactive sputtering. We find that the capture cross sections are thermally activated and steeply increase with increasing energy depth. Both features can be attributed to the same physical origin, indicating vibronic trap properties, where the capture mechanism is governed by multiphonon processes.
Low saturation fluence in a semiconductor saturable electroabsorber mirror operated in a self-biased regime
Authors: Ryvkin B. S. , Panajotov K. , Avrutin E. A.
Published: May 2008

A semiconductor saturable absorber mirror utilizing the electroabsorption effect on a self-biased stack of extremely shallow quantum wells is proposed and analyzed theoretically and numerically. The saturation flux and recovery time of the proposed device when operated with picosecond incident pulses are shown to compare very favorably with existing all-optical constructions.
The persistent photoconductivity effect in AlGaN/GaN heterostructures grown on sapphire and SiC substrates
Authors: Arslan Engin , Bütün Serkan , Lisesivdin S. Bora , Kasap Mehmet , Ozcelik Suleyman , Ozbay Ekmel
Published: May 2008

In the present study, we reported the results of the investigation of electrical and optical measurements in AlxGa1−xN/GaN heterostructures (x=0.20) that were grown by way of metal-organic chemical vapor deposition on sapphire and SiC substrates with the same buffer structures and similar conditions. We investigated the substrate material effects on the electrical and optical properties of Al0.20Ga0.80N/GaN heterostructures. The related electrical and optical properties of AlxGa1−xN/GaN heterostructures were investigated by variable-temperature Hall effect measurements, photoluminescence (PL), photocurrent, and persistent photoconductivity (PPC) that in turn illuminated the samples with a blue (λ=470 nm) light-emitting diode (LED) and thereby induced a persistent increase in the carrier density and two-dimensional electron gas (2DEG) electron mobility. In sample A (Al0.20Ga0.80N/GaN/sapphire), the carrier density increased from 7.59×1012 to 9.9×1012 cm−2 via illumination at 30 K. On the other hand, in sample B (Al0.20Ga0.80N/GaN/SiC), the increments in the carrier density were larger than those in sample A, in which it increased from 7.62×1012 to 1.23×1013 cm−2 at the same temperature. The 2DEG mobility increased from 1.22×104 to 1.37×104 cm−2/V s for samples A and B, in which 2DEG mobility increments occurred from 3.83×103 to 5.47×103 cm−2/V s at 30 K. The PL results show that the samples possessed a strong near-band-edge exciton luminescence line at around 3.44 and 3.43 eV for samples A and B, respectively. The samples showed a broad yellow band spreading from 1.80 to 2.60 eV with a peak maximum at 2.25 eV with a ratio of a near-band-edge excitation peak intensity up to a deep-level emission peak intensity ratio that were equal to 3 and 1.8 for samples A and B, respectively. Both of the samples that were illuminated with three different energy photon PPC decay behaviors can be well described by a stretched-exponential function and relaxation time constant τ as well as a decay exponent β that changes with the substrate type. The energy barrier for the capture of electrons in the 2DEG channel via the deep-level impurities (DX-like centers) in AlGaN for the Al0.20Ga0.80N/GaN/sapphire and Al0.20Ga0.80N/GaN/SiC heterojunction samples are 343 and 228 meV, respectively. The activation energy for the thermal capture of an electron by the defects ΔE changed with the substrate materials. Our results show that the substrate material strongly affects the electrical and optical properties of Al0.20Ga0.80N/GaN heterostructures. These results can be explained with the differing degrees of the lattice mismatch between the grown layers and substrates.
Nonequilibrium population distribution in excited electronic states of Tb3+ in Y3Al5O12
Authors: Gruber John B. , Sardar Dhiraj K. , Nash Kelly L. , Valiev Uygun V. , Sokolov Vladimir Yu. , Rakhimov Sharof A.
Published: May 2008

The Zeeman effect has been studied within the “green” range of luminescence due to the radiative 4f→4f transitions D54→F75 for the rare earth ion Tb3+ in yttrium aluminum garnet (Y3Al5O12) at a sample temperature of 85 K. The special features associated with the magnetic field dependence of the Zeeman splitting have been explained for transitions observed in the geometry of the longitudinal and transverse Zeeman effect. An analysis of the results obtained from the magneto-optical data indicates that in a magnetic field a nonequilibrium population distribution occurs between the sublevels of the quasidoublet state (Γ1,Γ4) in the D54 manifold. The energy of the quasidoublet state is approximately 20 585 cm−1.
Dielectric functions and optical constants modeling for CuIn3Se5 and CuIn5Se8
Authors: León M. , Serna R. , Levcenko S. , Nicorici A. , Merino J. M. , Friedrich E. J. , Arushanov E.
Published: May 2008

The complex dielectric functions, ε(ω)=ε1(ω)+iε2(ω), of CuIn3Se5 and CuIn5Se8 crystals with different Cu contents have been determined in the 0.8–4.7 eV photon energy range by using spectroscopic ellipsometry. The spectral dependence of the real, ε1(ω), and imaginary, ε2(ω), parts of ε(ω), as well as the complex refractive index, the absorption coefficient, and the normal-incidence reflectivity, has been modeled by using a modification of Adachi’s model. The results are in excellent agreement with the experimental data over the entire range of photon energies. The model parameters, including the energies corresponding to the lowest direct gap, E0, and to higher critical points, have been determined by using the simulated annealing algorithm.
Identification and quantification of components in ternary vapor mixtures using a microelectromechanical-system-based electronic nose
Authors: Zhao Weichang , Pinnaduwage Lal A. , Leis John W. , Gehl Anthony C. , Allman Steve L. , Shepp Allan , Mahmud Ken K.
Published: May 2008

We report the experimental details on the successful application of the electronic nose approach to identify and quantify components in ternary vapor mixtures. Preliminary results have recently been presented [L. A. Pinnaduwage et al., Appl. Phys. Lett. 91, 044105 (2007)]. Our microelectromechanical-system-based electronic nose is composed of a microcantilever sensor array with seven individual sensors used for vapor detection and an artificial neural network for pattern recognition. A set of custom vapor generators generated reproducible vapor mixtures in different compositions for training and testing of the neural network. The sensor array was selected to be capable of generating different response patterns to mixtures with different component proportions. Therefore, once the electronic nose was trained by using the response patterns to various compositions of the mixture, it was able to predict the composition of “unknown” mixtures. We have studied two vapor systems: one included the nerve gas simulant dimethylmethyl phosphonate at ppb concentrations and water and ethanol at ppm concentrations; the other system included acetone, water, and ethanol all of which were at ppm concentrations. In both systems, individual, binary, and ternary mixtures were analyzed with good reproducibility.
Analyses of the work required to delaminate a coating film from a substrate under oscillating load conditions and the film-substrate contact behavior after delamination
Authors: Liou Jeng Luen , Wei Pal Jen , Liang Wen Long , Ai Chi Fong , Lin Jen Fin
Published: May 2008

Nanoindentation tests in which oscillating loads were applied to specimens were carried out to study the work (Wf) required for a coating film to delaminate from its substrate. A sharp increase in the indentation depth occurred during coating film delamination. A theoretical model was developed for the present study to evaluate the difference between the work in the load-depth profiles obtained with and without delamination. Arranging that the maximum load was reached at the end of the loading process allowed us to obtain an approximately constant value for the indentation depth propagation rate during in one cycle. This allowed a determination of the number of oscillating cycles and, thus, the work required by assuming that there was no delamination during this delamination period. The depth propagation rates and the work required for coating film delamination were investigated by varying Pmax, Pmean, P0, and frequency (f). The depth propagation rates were slightly increased by increasing the Pmax value but were significantly lowered by increasing the frequency (f). The effects due to the changes in Pmean and P0 on the depth propagation rate were insignificant. The Wf value was slightly lowered by increasing the Pmax value but was significantly increased by increasing the oscillating load frequency (f). The effects of varying P0 and Pmean on the Wf value were found to be small. The Wf values showed an exponential drop when the depth propagation rate was increased; they were asymptotic to a constant value when the depth propagation rate was sufficiently high. Coating film delamination produced a sharp increase in the indentation depth even in the case of a very small load increase. The oscillating load-depth cycles appearing after delamination allowed us to establish the film-substrate contact behavior occurring during the loading/unloading process of one oscillating cycle.
Valence-band offset of epitaxial ZnO∕MgO (111) heterojunction determined by x-ray photoelectron spectroscopy
Authors: Li Y. F. , Yao B. , Lu Y. M. , Li B. H. , Gai Y. Q. , Cong C. X. , Zhang Z. Z. , Zhao D. X. , Zhang J. Y. , Shen D. Z. , Fan X. W.
Published: May 2008

The valence-band offset of ZnO∕MgO (111) heterojunction has been directly measured by x-ray photoelectron spectroscopy. Excluding the strain effect, the valence-band offset is determined to be 0.87±0.20eV, and the conduction-band offset ΔEC is deduced to be −3.59±0.20eV, indicating that ZnO∕MgO heterojunction has a type-I band alignment. The conduction-band and valence-band offset of MgO∕ZnO is used to interpret the origination of p-type conduction in undoped MgxZn1−xO alloy and deeper acceptor level in undoped and N-doped p-type MgxZn1−xO alloy than in ZnO.
Nanoscale three dimensional pattern formation in light emitting porous silicon
Authors: Chun Ik Su , Chow Edmond K. , Li Xiuling
Published: May 2008

A simple and efficient method for generating light emitting three-dimensional (3D) nanoscale pattern in silicon is presented. The method is based on differential chemical etching on and in-between patterned metal features. Effective transfer of various two-dimensional nanoscale (10–100nm) metal patterns on bulk silicon to 3D porous silicon network is demonstrated. The capability and limitations of this method are discussed.
Investigation of neodymium-diffused yttrium vanadate waveguides by confocal microluminescence
Authors: Benayas A. , Jaque D. , Hettrick S. J. , Wilkinson J. S. , Shepherd D. P.
Published: May 2008

We report on the confocal microspectroscopic characterization of planar optical waveguides fabricated in yttrium vanadate (YVO4) crystals by thermal diffusion of neodymium ions. We have found that the waveguide formation is accompanied by Nd3+ fluorescence quenching and by a redshift of the Nd3+ sub-Stark transitions. These effects have been explained in terms of the high Nd3+ concentrations achieved close to the diffusion surface, which lead to the appearance of nonradiative processes, as well as to a local compression in the surroundings of the indiffused Nd3+ ions. By comparing with previous works, we have estimated an equivalent residual stress of 0.1 GPa. The possible mechanisms at the origin of waveguide formation have been also discussed.
Oppositely rotating eigenmodes of spin-polarized current-driven vortex gyrotropic motions in elliptical nanodots
Authors: Lee Ki-Suk , Yu Young-Sang , Choi Youn-Seok , Jeong Dae-Eun , Kim Sang-Koog
Published: May 2008

The authors found that there exist two different rotational eigenmodes of oppositely rotating sense in spin-polarized current-driven vortex gyrotropic motions in soft magnetic elliptical nanodots. Simple mathematical expressions were analytically calculated by adopting vortex-core (VC)-rotation-sense-dependent dynamic susceptibility tensors based on the linearized Thiele equation [Phys. Rev. Lett. 30, 230 (1973)]. The numerical calculations of those analytical expressions were confirmed by micromagnetic simulations, revealing that linear-regime steady-state VC motions driven by any polarized oscillating currents can be interpreted simply by the superposition of the clockwise and counterclockwise rotational eigenmodes. The shape of the orbital trajectories of the two eigenmodes is determined only by the lateral dimension of elliptical dots. Additionally, the orbital radii and phases of the two eigenmodes’ VC motions were found to markedly vary with the frequency of applied currents, particularly across the vortex eigenfrequency and according to the vortex polarization, which results in overall VC motions driven by any polarized oscillating currents.
Temperature acceleration of structural relaxation in amorphous Ge2Sb2Te5
Authors: Ielmini D. , Lavizzari S. , Sharma D. , Lacaita A. L.
Published: May 2008

The structural relaxation (SR) process in an amorphous chalcogenide material (Ge2Sb2Te5) is studied by electrical measurements on phase-change memory devices. SR induces a change in the conduction regime from Poole to Poole–Frenkel transport, evidencing a temperature accelerated defect-annihilation process. Based on an Arrhenius kinetics with distributed activation energies, a temperature-acceleration law is shown, relating the time to reach a specific relaxed state to the temperature during isothermal experiments. This law is demonstrated comparing the time evolution of resistance for different temperatures. These results allow for a significant time reduction in reliability testing of devices and materials affected by SR.
Transversely isotropic elastic properties of single-walled carbon nanotubes by a rectangular beam model for the CC bonds
Authors: Li Haijun , Guo Wanlin
Published: May 2008

Continuum mechanics modeling of carbon nanotubes has long been an attractive issue, but how to reflect exactly the physics essential of the atomic bonds still remains to be a challenging problem. To capture the distinguishing in-plane σ-σ and out-of-plane σ-π bond angle bending rigidities of CC bonds in carbon nanotubes, an equivalent beam element with rectangular section is proposed and a corresponding frame structure model for a single-walled carbon nanotube (SWNT) is developed. By using the model, the five independent elastic moduli of SWNTs with arbitrary chirality and diameter are evaluated systematically. It is found that the elastic properties of the SWNTs are transversely isotropic when the tube diameter is small. The smaller the tube diameter is, the stronger the dependence of the elastic properties on the tube size and chirality is, while when the tube diameter is large enough, the SWNTs degenerate from transversely isotropic to isotropic and the elastic moduli tend to that of a graphite sheet. The present model can be incorporated into any standard finite element software directly, providing an extremely versatile and powerful tool for the study of nanostructures that beyond the computational capability of current atomistic approaches.
Conversion efficiencies of electron beam energy to vacuum ultraviolet light for Ne, Ar, Kr, and Xe excited with continuous electron beams
Authors: Morozov A. , Heindl T. , Krücken R. , Ulrich A. , Wieser J.
Published: May 2008

Continuous 8–15keV electron beams were used to excite Ne, Ar, Kr, and Xe at pressures ranging from 75to1400hPa. Conversion efficiencies of the energy deposited by the electron beam in the gas to vacuum ultraviolet light emitted from excimers are obtained. At pressures above 500hPa, the efficiencies show constant values of 0.31±0.06 for Ne, 0.33±0.04 for Ar, 0.42±0.05 for Kr, and 0.42±0.05 for Xe. Apparent energy conversion efficiencies for practical devices utilizing this excitation technique are also reported.
Measurement of optical loss variation on thickness of InGaN optical confinement layers of blue-violet-emitting laser diodes
Authors: Son J. K. , Lee S. N. , Paek H. S. , Sakong T. , Kim H. K. , Park Y. , Ryu H. Y. , Nam O. H. , Hwang J. S. , Cho Y. H.
Published: May 2008

An optical loss of GaN-based blue-violet laser diodes (BV-LDs) was measured by taking the intensity decay of edge emitting luminescence with respect to the distance from cleaved edge of a wafer to the position where an excitation laser was focused. Amplified spontaneous emission (ASE) was also investigated by tuning the power of an excitation laser on BV-LD wafers. Measurements were performed on wafers with different thicknesses of InGaN optical confinement layers (OCLs). The threshold power of ASE intensity was minimized at an optimum thickness of InGaN OCL. We also found that optical loss of wafers was determined by absorption of an InGaN layer in thicker OCL structure. From experimental data and fittings, we obtained 40 cm−1 for InGaN absorption at 405 nm. The optical field confined in OCL region was reasonably high enough to affect the overall modal loss in devices. Therefore, the optical losses still remained even though the Mg-doped GaN regions are far enough from the active layers. The crystal quality of an InGaN layer should be an important aspect to improve the performance of BV-LDs.
High efficiency deep-blue organic light-emitting diode with a blue dye in low-polarity host
Authors: Jou Jwo-Huei , Lin Yu-Pu , Hsu Mao-Fung , Wu Ming-Hsuan , Lu Ping
Published: May 2008

A high efficiency deep-blue organic light-emitting diode was fabricated using a blue light-emitting dye, 2,7-bis{2[phenyl(m-tolyl)amino]-9,9-dimethyl-fluorene-7-yl}-9,9-dimethyl—fluorene, doped in a low-polarity host, 4,4′-bis(9-carbazolyl)-biphenyl. The resulting device showed a highly saturated blue light with Commission Internationale de l’Eclairage coordinates of (0.14, 0.08) and a record-high external quantum efficiency of 5.1% at 100cd∕m2. The highly saturated blue emission may be attributed to effective solid-state solvation of the employed host, being able to effectively separate the blue dopants due to similar host-guest polarity. The high efficiency may result from efficient energy transfer from the host to dopant and a proper device architecture, leading excitons to favorably form on the host instead of on the dopant.
Stress induced martensite in epitaxial Ni–Mn–Ga films deposited on MgO(001)
Authors: Thomas M. , Heczko O. , Buschbeck J. , Schultz L. , Fähler S.
Published: May 2008

Biaxial tensile stress in epitaxial Ni52Mn23Ga25 films on MgO(001) was measured at different temperatures using an adapted x-ray stress analysis. A stress of up to 105MPa originates from different thermal expansions of substrate and film and partially from the substrate-film misfit. The film transforms to twinned orthorhombic martensite at 319K. The stress increases the martensitic transformation temperature of about 63K. This is in good agreement with respect to the transformation temperature expected from the composition of the film. The presence of biaxial tensile stress leads to twin boundary selection, hence, there are no twin planes perpendicular to the substrate.
High-Q active ring microwave resonators based on ferrite-ferroelectric layered structures
Authors: Ustinov Alexey B. , Srinivasan G. , Kalinikos Boris A.
Published: May 2008

An electric and magnetic field tunable (dual-tunable) microwave active ring resonator is designed and characterized. The device structure is implemented with a microwave amplifier and a ferrite-ferroelectric delay line in the feedback loop. At 8GHz, an effective Q factor of 50 000 and tuning by 5MHz with an electric field are achieved. The performance characteristics of the resonator are presented and discussed.
Characterization of granular compaction by nonlinear acoustic resonance method
Authors: Inserra C. , Tournat V. , Gusev V.
Published: May 2008

A method of nonlinear acoustic resonance is applied to monitor the evolution in the linear and nonlinear elastic and dissipative mechanical properties of a granular packing in the process of its compaction by consecutive mechanical taps. It is demonstrated that the variations in the nonlinear mechanical properties are more pronounced than those in the linear ones, indicating the advantage of nonlinear acoustic methods for the compaction control. The experimental observations revealed for the first time the modification in the statistical distribution of the grain-grain contact interaction forces by the compaction.
Detection of the valence band in buried Co2MnSi–MgO tunnel junctions by means of photoemission spectroscopy
Authors: Fecher Gerhard H. , Balke Benjamin , Gloskowskii Andrei , Ouardi Siham , Felser Claudia , Ishikawa Takayuki , Yamamoto Masafumi , Yamashita Yoshiyuki , Yoshikawa Hideki , Ueda Shigenori , Kobayashi Keisuke
Published: May 2008

This work reports on the detection of the valence band of buried Heusler compounds by means of hard x-ray photoemission spectroscopy. The measurements have been performed on the so-called “half” tunnel junctions that are thin films of Co2MnSi underneath MgO. Starting from the substrate, the structure of the samples is MgO(buffer)–Co2MnSi–MgO(tMgO)–AlOx with a thickness tMgO of the upper MgO layer of 2 and 20nm. The valence band x-ray photoemission spectra have been excited by hard x rays of about 6keV energy. The valence band spectra have been used to estimate the mean free path of the electrons through the MgO layer to be 17nm at kinetic energies of about 6keV. In particular, it is shown that the buried Co2MnSi films exhibit the same valence density of states as in bulk samples.
Influence of pulse width on electroluminescence and junction temperature of AlInGaN deep ultraviolet light-emitting diodes
Authors: Zhang J. C. , Zhu Y. H. , Egawa T. , Sumiya S. , Miyoshi M. , Tanaka M.
Published: May 2008

The behavior of electroluminescence (EL) and junction temperature of AlInGaN deep ultraviolet light-emitting diodes under pulse-width modulation is investigated. The redshift of both emissions from quantum-well (P1) and localized (P2) states in the EL spectra and the increase of intensity ratio of P1 to P2 are observed with the increase of duty cycle. The photoluminescence of p-GaN contact layer is adopted to measure the junction temperature, which shows a linear relation with the duty cycle. Meanwhile, the duty cycle coefficient of junction temperature increases with the increase of injection current. The EL behaviors are explained by the thermal effect induced by pulse current at high duty cycle.
X-ray-excited photoelectron detection using a scanning tunneling microscope
Authors: Rose V. , Freeland J. W. , Gray K. E. , Streiffer S. K.
Published: May 2008

Detection of x-ray-enhanced electrons emitted by synchrotron radiation with the tip of a scanning tunneling microscope has the potential to open a path to high-resolution microscopy with chemical sensitivity. Nonresonant photoejected electrons typically yield a current background of a few hundred picoamperes at a bare tip. Coating the tip with an insulating boron nitride film can effectively reduce this background. In this configuration, we have quantitatively studied the bias dependent photoelectron collection for tip/sample separations of 400–1600nm, where quantum mechanical tunneling does not contribute.
Acidity enhances the formation of a persistent ozonide at aqueous ascorbate/ozone gas interfaces
Authors: Enami Shinichi , Hoffmann M. R. , Colussi A. J.
Published: May 2008

The pulmonary epithelium, like most aerial biosurfaces, is naturally protected against atmospheric ozone (O
3
) by fluid films that contain ascorbic acid (AH
2
) and related scavengers. This mechanism of protection will fail, however, if specific copollutants redirect AH
2
and O
3
(g) to produce species that can transduce oxidative damage to underlying tissues. Here, the possibility that the synergistic adverse health effects of atmospheric O
3
(g) and acidic particulate matter revealed by epidemiological studies could be mediated by hitherto unidentified species is investigated by electrospray mass spectrometry of aqueous AH
2
droplets exposed to O
3
(g). The products of AH
2
ozonolysis at the relevant air–water interface shift from the innocuous dehydroascorbic acid at biological pH to a C
4
-hydroxy acid plus a previously unreported ascorbate ozonide (
m
/
z
= 223) below pH ≈5. The structure of this ozonide is confirmed by tandem mass spectrometry and its mechanism of formation delineated by kinetic studies. Present results imply enhanced production of a persistent ozonide in airway-lining fluids acidified by preexisting pathologies or inhaled particulate matter. Ozonides are known to generate cytotoxic free radicals
in vivo
and can, therefore, transduce oxidative damage.
Congruity Effects in Time and Space: Behavioral and ERP Measures
Authors: Teuscher Ursina , McQuire Marguerite , Collins Jennifer , Coulson Seana
Published: May 2008

Two experiments investigated whether motion metaphors for time affected the perception of spatial motion. Participants read sentences either about literal motion through space or metaphorical motion through time written from either the ego‐moving or object‐moving perspective. Each sentence was followed by a cartoon clip. Smiley‐moving clips showed an iconic happy face moving toward a polygon, and shape‐moving clips showed a polygon moving toward a happy face. In Experiment 1, using an explicit judgment task, participants judged smiley‐moving cartoons as related to ego‐moving sentences about space and about time, and shape‐moving cartoons as related to object‐moving sentences. In Experiment 2, participants viewed the same stimuli, but the cartoons were task‐irrelevant. Event‐related brain potentials revealed an early attentional effect of congruity on cartoons following sentences about space, and a later semantic effect on cartoons following sentences about time. Results are most consistent with accounts that posit differences in the processing of novel and conventional metaphors.
Bootstrapping Cognition from Behavior—A Computerized Thought Experiment
Authors: Möller Ralf , Schenck Wolfram
Published: May 2008

We show that simple perceptual competences can emerge from an internal simulation of action effects and are thus grounded in behavior. A simulated agent learns to distinguish between dead ends and corridors without the necessity to represent these concepts in the sensory domain. Initially, the agent is only endowed with a simple value system and the means to extract low‐level features from an image. In the interaction with the environment, it acquires a visuo‐tactile forward model that allows the agent to predict how the visual input is changing under its movements, and whether movements will lead to a collision. From short‐term predictions based on the forward model, the agent learns an inverse model. The inverse model in turn produces suggestions about which actions should be simulated in long‐term predictions, and long‐term predictions eventually give rise to the perceptual ability.
The Weckud Wetch of the Wast: Lexical Adaptation to a Novel Accent
Authors: Maye Jessica , Aslin Richard N. , Tanenhaus Michael K.
Published: May 2008

Two experiments investigated the mechanism by which listeners adjust their interpretation of accented speech that is similar to a regional dialect of American English. Only a subset of the vowels of English (the front vowels) were shifted during adaptation, which consisted of listening to a 20‐min segment of the “Wizard of Oz.” Compared to a baseline (unadapted) condition, listeners showed significant adaptation to the accented speech, as indexed by increased word judgments on a lexical decision task. Adaptation also generalized to test words that had not been presented in the accented passage but that contained the shifted vowels. A control experiment showed that the adaptation effect was specific to the direction of the shift in the vowel space and not to a general relaxation of the criterion for what constitutes a good exemplar of the accented vowel category. Taken together, these results provide evidence for a context‐specific vowel adaptation mechanism that enables a listener to adjust to the dialect of a particular talker.
Perceptual Processing Affects Conceptual Processing
Authors: Van Dantzig Saskia , Pecher Diane , Zeelenberg René , Barsalou Lawrence W.
Published: May 2008

According to the Perceptual Symbols Theory of cognition (), modality‐specific simulations underlie the representation of concepts. A strong prediction of this view is that perceptual processing affects conceptual processing. In this study, participants performed a perceptual detection task and a conceptual property‐verification task in alternation. Responses on the property‐verification task were slower for those trials that were preceded by a perceptual trial in a different modality than for those that were preceded by a perceptual trial in the same modality. This finding of a modality‐switch effect across perceptual processing and conceptual processing supports the hypothesis that perceptual and conceptual representations are partially based on the same systems.
The Benefits of Sensorimotor Knowledge: Body–Object Interaction Facilitates Semantic Processing
Authors: Siakaluk Paul D. , Pexman Penny M. , Sears Christopher R. , Wilson Kim , Locheed Keri , Owen William J.
Published: May 2008

This article examined the effects of body–object interaction (BOI) on semantic processing. BOI measures perceptions of the ease with which a human body can physically interact with a word's referent. In Experiment 1, BOI effects were examined in 2 semantic categorization tasks (SCT) in which participants decided if words are easily imageable. Responses were faster and more accurate for high BOI words (e.g., mask) than for low BOI words (e.g., ship). In Experiment 2, BOI effects were examined in a semantic lexical decision task (SLDT), which taps both semantic feedback and semantic processing. The BOI effect was larger in the SLDT than in the SCT, suggesting that BOI facilitates both semantic feedback and semantic processing. The findings are consistent with the embodied cognition perspective (e.g., , Perceptual Symbols Theory), which proposes that sensorimotor interactions with the environment are incorporated in semantic knowledge.
LIFEWORLDS IN AN ENLARGED EUROPE
Authors: Masso Anu
Published: May 2008

This article analyses the personal spatiality of people with different economic and cultural backgrounds, using Estonia as an example of a ‘new’ EU country and Sweden as an example of an ‘old’ one. On the basis of survey data, the contacts, interest and feeling of cultural closeness of different cultures and the connections of these with socio-demographic variables, societal trust, and regional identities are analysed. The results show that personal spatiality is spread homogeneously over social groups in Sweden. In Estonia, personal spatiality differentiates socio-demographic groups and is related to general social trust. The society is separated into a personally ‘globalised’ group and a group that feels uncertainty in connection with EU enlargement and globalisation. In the new member states of the EU, cultural adaptation without overcoming transition trauma may cause cultural isolation, even xenophobia. Avoiding resistance against transcultural communication patterns contributes to the development of common values and interregional economic cooperation between EU member states.
EUROPE'S OTHER
Authors: Strasser Sabine
Published: May 2008

As ‘Eurobarometer’ surveys indicate, European populations are increasingly sceptical about further EU enlargement, especially as far as Turkey is concerned. Austria's rejection of negotiations with Turkey has been remarkable. While the Austrian government has been in line with European council resolutions, policy makers of different parties have reiterated their claim for alternatives to full membership for Turkey. Furthermore, opinion polls have shown that the Austrian population's refusal of Turkey is above EU average. Embedded in the popular arguments why Turkey should stay outside the EU, we find what Ralf Grillo has called ‘cultural anxiety’: essentialist views of ‘our’ and ‘their’ culture cause fears about a fast growing and predominantly Muslim population that would flow into EU labour markets and threaten ‘us’, in particular ‘our’ democracy, equality and human rights. Against this backdrop my interest will neither be focused on a further analysis of whether Turkey is sufficiently prepared for EU accession nor on the European Union's absorption capacity. In this paper I will rather focus on the emergence of hegemonic and counter-hegemonic cultural practices of selfing and othering in order to better understand the extensive refusal of Turkey's EU accession in Austria.
EUROPEAN CULTURAL SPACE IN THE EUROPEAN CITIES OF CULTURE
Authors: Sassatelli Monica
Published: May 2008

This article considers the role of European Union (EU) cultural policy within the process of Europeanization. It will trace the development of EU competence on cultural matters in general, and of the flagship programme ‘European City of Culture’ in particular. The latter will be observed both in its overall implementation and in the exceptional edition of 2000, when in order to celebrate the millennium nine cities shared the title, allegedly bringing the European reconfiguration of space into full light. This will show that the minutiae of cultural policy-making are never far removed from far-reaching discourses on European identity. How the gap is overcome, rhetorically and practically, provides the strategic vantage point for analyzing how the creation of a ‘European cultural space’ may be suggesting new ways to think of spatiality in its connection to culture and identity formation.
THE SUBSIDIARIZATION OF SOCIAL POLICIES: ACTORS, PROCESSES AND IMPACTS
Authors: Kazepov Yuri
Published: May 2008

This paper seeks to disentangle analytically the trends towards the subsidiarization of social policies in Europe addressing how the social policy reforms changed actors’ governance arrangements and altered the government scales involved over the last few decades. Following an introductory analysis of the main causes of the subsidiarization of social policies (sections 1 and 2), attention is devoted to the differences between welfare systems in Europe (section 3) and the way they influence the directions of change. The hypothesis is that, despite the fact that the subsidiarization of social policies is a converging rhetoric in most European countries’ social policy reforms, the impact of the process varies according to the specificities of the respective regulatory frames at the national or sub-national scales. This is exemplified in the final part of the paper (section 4) which considers the Italian case and the main critical dimensions that emerge through these processes.