bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential interferometry for measurement of density fluctuations and fluctuation-induced transport (invited)
Authors: Lin L. , Ding W. X. , Brower D. L. , Bergerson W. F. , Yates T. F.
Published: October 2010

Differential interferometry employs two parallel laser beams with a small spatial offset (less than beam width) and frequency difference (1–2 MHz) using common optics and a single mixer for a heterodyne detection. The differential approach allows measurement of the electron density gradient, its fluctuations, as well as the equilibrium density distribution. This novel interferometry technique is immune to fringe skip errors and is particularly useful in harsh plasma environments. Accurate calibration of the beam spatial offset, accomplished by use of a rotating dielectric wedge, is required to enable broad application of this approach. Differential interferometry has been successfully used on the Madison Symmetric Torus reversed-field pinch plasma to directly measure fluctuation-induced transport along with equilibrium density profile evolution during pellet injection. In addition, by combining differential and conventional interferometry, both linear and nonlinear terms of the electron density fluctuation energy equation can be determined, thereby allowing quantitative investigation of the origin of the density fluctuations. The concept, calibration, and application of differential interferometry are presented.
Upgrade of far-infrared laser-based Faraday rotation measurement on MST
Authors: Ding W. X. , Brower D. L. , Bergerson W. F. , Lin L.
Published: October 2010

Recently, the far-infrared (FIR) laser (λ0=432 μm) Faraday rotation measurement system on MST has been upgraded. The dc flowing-gas discharge CO2 pump laser is replaced by a rf-excited, sealed CO2 laser at 9.27 μm (GEM select 100, Coherent Inc., Santa Clara, CA), which is subdivided equally into three parts to simultaneously pump three FIR cavities. The total infrared pump power is approximately 80 W on the 9R(20) line required to pump the formic acid molecule. Each FIR cavity produces ∼12 mW, sufficient for 11 simultaneous chord interferometry-polarimetry operations. Three key issues [(1) conservation of circularly polarized wave, (2) colinearity of two probe waves, and (3) stability of intermediate frequencies between lasers] affecting the Faraday rotation measurement have been resolved experimentally.
Initial operation of a pulse-burst laser system for high-repetition-rate Thomson scattering
Authors: Harris W. S. , Den Hartog D. J. , Hurst N. C.
Published: October 2010

A pulse-burst laser has been installed for Thomson scattering measurements on the Madison Symmetric Torus reversed-field pinch. The laser design is a master-oscillator power-amplifier. The master oscillator is a commercial Nd:YVO4 laser (1064 nm) which is capable of Q-switching at frequencies between 5 and 250 kHz. Four Nd:YAG (yttrium aluminum garnet) amplifier stages are in place to amplify the Nd:YVO4 emission. Single pulses through the Nd:YAG amplifier stages gives energies up to 1.5 J and the gain for each stage has been measured. Repetitive pulsing at 10 kHz has also been performed for 2 ms bursts, giving average pulse energies of 0.53 J with ΔE/E of 4.6%, where ΔE is the standard deviation between pulses. The next step will be to add one of two Nd:glass (silicate) amplifier stages to produce final pulse energies of 1–2 J for bursts up to 250 kHz.
Thermally controlled preferential molecular aggregation state in a thiacarbocyanine dye
Authors: Passier Rémy , Ritchie James P. , Toro Carlos , Diaz Carlos , Masunov Artëm E. , Belfield Kevin D. , Hernandez Florencio E.
Published: October 2010

Herein we report the experimental and theoretical study of the temperature dependence of a thiacarbocyanine dye in its monomer, H- and J-aggregates states. We demonstrate the ability to control the ratio of monomer, H- and/or J-aggregates with heat. We link such a control to the conformation dependence of the molecule. An alternative way to gain access to the dominating species without changing the concentration as a complete switching mechanism between all the present species is proposed. The results presented in this work lead to a better understanding of thiacarbocyanine dye’s behavior.
Electromagnetic bound states in the radiation continuum for periodic double arrays of subwavelength dielectric cylinders
Authors: Ndangali Rémy F. , Shabanov Sergei V.
Published: October 2010

Electromagnetic bound states in the radiation continuum are studied for periodic double arrays of subwavelength dielectric cylinders in TM polarization. They are similar to localized waveguide mode solutions of Maxwell’s equations for metal cavities or defects of photonic crystals, but, in contrast to the latter, their spectrum lies in the radiation continuum. The phenomenon is identical to the existence of bound states in the radiation continuum in quantum mechanics, discovered by von Neumann and Wigner. In the formal scattering theory, these states appear as resonances with the vanishing width. For the system studied, the bound states are shown to exist at specific distances between the arrays in the spectral region where one or two diffraction channels are open. Analytic solutions are obtained for all bound states (below the radiation continuum and in it) in the limit of thin cylinders (the cylinder radius is much smaller than the wavelength). The existence of bound states is also established in the spectral region where three and more diffraction channels are open, provided the dielectric constant and radius of the cylinders are fine-tuned. The near field and scattering resonances of the structure are investigated when the distance between the arrays varies in a neighborhood of its critical values at which the bound states are formed. In particular, it is shown that the near field in the scattering process becomes significantly amplified in specific regions of the array as the distance approaches its critical values. The effect may be used to control optical nonlinear effects by varying the distance between the arrays near its critical values.
A comparison between physical properties of carbon black-polymer and carbon nanotubes-polymer composites
Authors: Adohi B. J.-P. , Mdarhri A. , Prunier C. , Haidar B. , Brosseau C.
Published: October 2010

Multiple-walled carbon nanotube (CNT)-and carbon black (CB)-polymer composites have been fabricated by mechanical mixing with different loadings, the polymeric matrix being identical between the two series of samples. The main focus of this work is to report measurements of physical properties of these mixtures in ambient conditions and to discuss the origin of similarities and differences among them according the kind of carbonaceous filler. The uniform dispersion of the carbonaceous phase in the dielectric matrix was probed by high-resolution transmission electron microscopy. The good dispersibility of the filler particle is also reflected in the much lower conduction threshold observed for CNT-containing samples than in the CB composites. This is likely due to the high aspect ratio of the CNTs. Mechanical properties show that the storage modulus of the two kinds of samples is close to the modulus value of the neat styrene-butadiene rubber (SBR), independent of filler content over a wide range of compositions (ϕ<0.1) encompassing the percolation threshold. Microwave measurements show that the real part of the effective permittivity exhibits a flat frequency response, with the exception of the sample containing 30 vol % CB for which an inverse-power law is observed revealing a behavior that has been seen for many random heterogeneous soft materials. No resonant dielectric absorption is evidenced within the frequency range explored and for the filler concentrations investigated. The results were also compared with analytical effective (mean-field) models. The symmetric Bruggeman model is in very good agreement with the microwave effective permittivity once account is taken of the depolarization factor which is close to the value found for a three-dimensional (3D) random dispersion of monodisperse spherical conductive inclusions within a dielectric matrix. By combining microwave frequency-domain spectroscopy with uniaxial tension, we obtain the effective permittivity as a function of the elongation ratio. Our results indicate that the effective permittivity spectrum of the CNT-polymer samples and their CB-based counterparts is not very sensitive to the applied stress in the range of elongation ratios explored. For the sample containing 30 vol % CB, the relative variation in the effective permittivity as a function of the elongation ratio is well described by the Gaussian molecular network model. The experimentally determined mechanical and microwave properties of these nanocomposites is related to the change in the mesostructure, formed by the heterogeneous 3D interconnected network of polymer and of aggregates (or agglomerates) of filler particles, as the composite is stretched. The results of this study provide another insight and opportunities to the comprehension of multifunctional materials, including novel nanoelectronic components, and carbon-based systems.
Quantum state-selected photodissociation dynamics of H2O: Two-photon dissociation via the C̃ electronic state
Authors: Yuan Kaijun , Cheng Yuan , Cheng Lina , Guo Qing , Dai Dongxu , Yang Xueming , Dixon Richard N.
Published: October 2010

The photodissociation dynamics of H2O via the C̃ state by two-photon excitation has been investigated using the H atom Rydberg tagging time-of-flight technique. The rotational resolved action spectrum of the C̃←X̃ transition band has been measured. The line widths show a pronounced dependence on the parent rotational excitation in the C̃ state. The quantum state resolved OH product translational energy distributions and angular distributions have also been obtained. By carefully simulating these distributions, quantum state distributions of the OH product as well as the state-resolved angular anisotropy parameters were determined. The experimental results confirm the variation of two competitive predissociation pathways. A heterogeneous predissociation channel is mediated by rotational coupling to the B̃ A11 state associated with the a-axis (ka′), and a homogeneous pathway arises from purely electronic coupling to the Ã B11 state. We have also obtained the branching ratios of the OH(X) and OH(A) products, and related these to the C̃→Ã and C̃→B̃ pathways. The branching ratios display a strong ka′ dependence.
Nonstationary homoclinic orbits for an infinite-dimensional Hamiltonian system
Authors: Yang Minbo
Published: October 2010

We study the following system of diffusion equations on R×RN, ∂tu−Δxu+V(x)u=g(t,x,v), −∂tv−Δxv+V(x)v=f(t,x,u), where z=(u,v):R×RN→R2, V∊C(RN,R), g(t,x,v), f(t,x,u) are periodic in t, x and superlinear at infinity. By a variant linking theorem and concentration compactness arguments, we establish the existence of nonstationary homoclinic-type solutions of least energy for this systems.
Application of smooth exterior scaling method to study the time dependent dynamics of H2+ in intense laser field
Authors: Kalita Dhruba Jyoti , Gupta Ashish K.
Published: October 2010

A study of the multiphoton dissociation of H2+ in intense laser field using the smooth exterior scaling method to calculate resonance states is presented. This method is very attractive as it does not disturb the interaction region. The wave functions calculated with this method provide indisputable proof in support of the mechanisms of the different phenomena happening during photodissociation. Wave functions corresponding to the “vibrationally trapped” (bond-hardening) states are found. A unequivocal mechanism for “bond-softening” is provided. It is observed that with an increase in intensity, the lifetime of low vibrational level increases. The mechanism for this novel phenomenon is also explained.
Mobility of a single alkali metal atom on fullerene C60: First principles molecular dynamical study
Authors: Ramaniah Lavanya M. , Boero Mauro
Published: October 2010

The dynamical behavior of a single K or Na alkali metal atom on the surface of a C60 molecule is investigated via Car–Parrinello molecular dynamics simulations in a temperature range up to 300 K. These provide direct evidence for the heteroatom motion, postulated earlier in pioneering experiments, and show that an alkali metal atom can move both on the surface and radially outward from the surface, resulting in a dynamics ranging from diffusive to free orbital motion, on time-scales of up to a few picoseconds.
Dynamics of resistance switching induced by charge carrier fluence
Authors: Buh Gyoung-Ho , Hwang Inrok , Park Bae Ho
Published: October 2010

We investigated the dynamics of reversible resistance switching of NiO nonvolatile memory devices by measuring the switching time as a function of applied voltage. A model of local switching induced by charge carrier fluence was proposed to explain the time-dependent switching behaviors. Charge carrier flow under Poole–Frenkel emission builds up local conductive paths inside NiO. The enhanced electric field at the ends of conductive clusters abruptly increases local Poole–Frenkel emission and accelerates the percolation propagation. The results of Monte Carlo calculation strongly supported the model of local switching induced by charge carrier fluence.
Effects of off-stoichiometry and density on the magnetic and magneto-optical properties of yttrium iron garnet films by magnetron sputtering method
Authors: Yang Qing-Hui , Zhang Huai-Wu , Wen Qi-Ye , Liu Ying-Li
Published: October 2010

Yttrium iron garnet films were deposited on Si and Si/CeO2 substrates by magnetron sputtering method followed by postannealing. By varying the fabrication parameters such as sputtering atmosphere, sputtering power, and annealing atmosphere, single phase garnet films were obtained with different off-stoichiometry and film density. The dependence of cation ratio, magnetic and magneto-optical characteristics, and absorption coefficient were systemically investigated. The results reveal that a proper oxygen pressure in both sputtering and annealing process give rise to a small cation ratio of (Fe2+ or Fe4+)/Fe3+, thus is beneficial to obtain large saturation magnetization, large Faraday rotation, and small optical absorption. The sputtering power can also affect the properties of the film through changing the film density. Our results indicate that the properties of sputtering deposited yttrium iron garnet (YIG) film can be easily tuned and optimized by modifying the off-stoichiometry and density of the film, thus provides flexibility to fabricate YIG film for extensive applications.
Self-consistent electrodynamics of large-area high-frequency capacitive plasma discharge
Authors: Chen Zhigang , Rauf Shahid , Collins Ken
Published: October 2010

Capacitively coupled plasmas (CCPs) generated using high frequency (3–30 MHz) and very high frequency (30–300 MHz) radio-frequency (rf) sources are used for many plasma processing applications including thin film etching and deposition. When chamber dimensions become commensurate with the effective rf wavelength in the plasma, electromagnetic wave effects impose a significant influence on plasma behavior. Because the effective rf wavelength in plasma depends upon both rf and plasma process conditions (e.g., rf power and gas pressure), a self-consistent model including both the rf power delivery system and the plasma discharge is highly desirable to capture a more complete physical picture of the plasma behavior. A three-dimensional model for self-consistently studying both electrodynamic and plasma dynamic behavior of large-area (Gen 10, >8 m2) CCP is described in this paper. This model includes Maxwell’s equations and transport equations for charged and neutral species, which are coupled and solved in the time domain. The complete rf plasma discharge chamber including the rf power delivery subsystem, rf feed, electrodes, and the plasma domain is modeled as an integrated system. Based on this full-wave solution model, important limitations for processing uniformity imposed by electromagnetic wave propagation effects in a large-area CCP (3.05×2.85 m2 electrode size) are studied. The behavior of H2 plasmas in such a reactor is examined from 13.56 to 200 MHz. It is shown that various rectangular harmonics of electromagnetic fields can be excited in a large-area rectangular reactor as the rf or power is increased. The rectangular harmonics can create not only center-high plasma distribution but also high plasma density at the corners and along the edges of the reactor.
The effect of multiple defects on the energy barrier of magnetization reversal
Authors: Yu Xian , Zhu Yuejin , Zhang Shufeng , Tong Chaohui
Published: October 2010

The effect of multiple defects on the energy barrier of magnetization reversal in a one-dimensional magnetic nanowire is studied. By numerically solving the double Sine–Gordon equation via the finite-difference method, we obtain the energy saddle point through which the initial magnetic state jumps to the final ground states. The energy barrier which is defined as the difference between the energies of the saddle point and the initial states is calculated for various defect parameters. It is found that the energy barrier strongly depend on the number and distribution of the defects. For given defects, there exists an optimal distribution for a minimum energy barrier.
Surface damages in diamond by Ar/O2 plasma and their effect on the electrical and electrochemical characteristics of boron-doped layers
Authors: Denisenko A. , Romanyuk A. , Pietzka C. , Scharpf J. , Kohn E.
Published: October 2010

Epitaxial single crystal and boron-doped diamond layers were exposed to reactive ion etching in Ar/O2 plasma (rf power of 25 W and self-bias of 100 V); and the electrical, structural, and electrochemical characteristics of the exposed surface were investigated. Angle-resolved x-ray photoemission spectroscopy (XPS) measurements revealed a nonuniform layer of amorphous carbon at the exposed surface with an average thickness of approximately 4 nm, as confirmed also by atomic force microscopy profiling of selectively etched areas. On highly boron-doped diamond, the plasma-induced damages resulted also in a nonconductive surface layer. This damaged and insulating surface layer remained resistant to graphite-etching chemicals and to rf oxygen plasma but it was removed completely in microwave hydrogen plasma at 700 °C. The surface characteristics after the H-plasma process followed by wet chemical oxidation were restored back to the initial state, as confirmed by XPS. Such “recovery” treatment had been applied to an all-diamond submicrometer electrode array initially patterned by an Ar/O2 plasma etching. The electrochemical characteristics of this electrode array were improved by more than two orders of magnitude, approaching theoretical limit for the given geometrical configuration.
Effects of total thickness on (001) texture, surface morphology, and magnetic properties of [Fe/Pt]n multilayer films by monatomic layer deposition
Authors: Yu Y. S. , George T. A. , Li W. L. , Yue L. P. , Fei W. D. , Li Haibo , Liu Mei , Sellmyer D. J.
Published: October 2010

Atomic-scale [Fe/Pt]n multilayer films with different total thickness were prepared on thermally oxidized Si (100) substrates at room temperature by monatomic layer deposition using dc-magnetron and rf-magnetron sputtering. Effects of the total thickness on (001) texture, surface morphology, and magnetic properties of the postannealed films have been investigated. It is found that the particlelike structure films with perfect (001) texture and perpendicular magnetic anisotropy are obtained with a thickness of less than or equal to 6.5 nm. After 500 °C annealing, the films with thickness of 6.5 and 11.9 nm show very smooth surface. In addition, with increasing total thickness of the films, (001) texture and perpendicular magnetic anisotropy of the annealed films deteriorate, and the films become continuous in structure. The total thickness of the films also affects the exchange-coupling interaction among FePt magnetic grains and the magnetization reversal process.
Electric-field-induced phase switching in the lead free piezoelectric potassium sodium bismuth titanate
Authors: Royles A. J. , Bell A. J. , Jephcoat A. P. , Kleppe A. K. , Milne S. J. , Comyn T. P.
Published: October 2010

High-energy synchrotron radiation has been used to demonstrate an electric-field-induced phase transformation in the ceramic xK1/2Bi1/2TiO3–(1−x)Na1/2Bi1/2TiO3, x=0.2. Application of an electric field ≥2 kV mm−1 leads to a transformation from single phase rhombohedral to a mixture of tetragonal and rhombohedral phases. The texturing of the tetragonal phase increases with field strength. The electric-field-induced transformation suggests an excursion into the morphotropic phase boundary in this system. The compositions x=0.1 and 0.3 reveal rhombohedral and tetragonal symmetry, respectively, both before and after the application of an electric field.
Area-transformation method for designing invisible cloaks
Authors: Wang Xinhua , Qu Shaobo , Wu Xiang , Wang Jiafu , Xu Zhuo , Ma Hua
Published: October 2010

By means of area-transformation method, the material parameters of the invisible cloaks in elliptic-cylindrical and spherical coordinates were obtained. The material parameters of the invisible cloaks are nonsingular and the cloaks can operate in a wide bandwidth due to the area-transformation rather than the point-transformation. The invisible properties of the cloaks are nearly perfect when the original area is small enough compared with its counterpart in the transformed space. Full wave simulations based on finite element method verified the designed cloaks.
All-angle blockage of sound by an acoustic double-fishnet metamaterial
Authors: Christensen J. , Martín-Moreno L. , García-Vidal F. J.
Published: October 2010

In this paper we design an acoustic metamaterial for broadband sound blockage that is easy to fabricate and presents tunable capabilities. Two adjacent holey plates are predicted to support a gap mode which is responsible of a forbidden band, displaying a negative effective bulk modulus. This acoustic metamaterial exhibits a weak dispersion with parallel momentum implying that strong attenuation appears for a broad range of angles of incident sound. Its bandwidth can be tailored at will by varying the separation between the two holey plates.
Characterization of coupled micro/nanoresonators using inverse eigenvalue analysis
Authors: Choubey Bhaskar , Anthony Carl , Saad Nor Hayati , Ward Mike , Turnbull Ross , Collins Steve
Published: October 2010

This paper reports a method of determining the system matrix of a nearest neighbor coupled array of micro/nanomechanical resonators. The simple method requires contacts to only one element of the array to determine two sets of eigenvalues related to the system matrix. The elements of the system matrix are then determined from these eigenvalues. This system matrix can then be used to determine the characteristics of the individual resonators or as the starting point for a perturbation analysis to determine the changes observed when a functionalized array of resonators is used as a sensor.
Reduction of nonradiative recombination center for ZnO films grown under Zn-rich conditions by metal organic chemical vapor deposition
Authors: Fujimoto Eiji , Watanabe Kenji , Matsumoto Yuji. , Koinuma Hideomi , Sumiya Masatomo
Published: October 2010

ZnO films were grown by metalorganic chemical vapor deposition using the repeated temperature modulation in an H2 ambient. The crystalline quality, as defined by the full-width at half-maximum of the ω (101¯1) reflection, was found to be correlated with the photoluminescence (PL) lifetime at 300 K. The fine structure of the PL spectra for the samples grown under Zn-rich condition at 8 K indicated the higher order (n=2) structure of free exciton A, two electron satellites and phonon-replicas. The internal quantum efficiency and the PL lifetime at 300 K were 5.5% and 2.6 ns, respectively, indicating a reduction in Zn vacancies in the ZnO films.
Fiber-connectorized micropillar cavities
Authors: Haupt Florian , Oemrawsingh Sumant S. R. , Thon Susanna M. , Kim Hyochul , Kleckner Dustin , Ding Dapeng , Suntrup Donald J. , Petroff Pierre M. , Bouwmeester Dirk
Published: October 2010

We present a cryogenically compatible method for permanently connecting and coupling a single mode fiber to a single mode of a micropillar cavity with embedded quantum dots (QDs). Efficient coupling of up to 40% was measured which requires a 300 nm positioning accuracy that remains preserved during the fiber attachment procedure and during cool-down to 4 K. Fiber coupling, as opposed to conventional free space coupling, makes it possible to connect many such QD-cavity systems within the same cryostat which can interact through an external optical network, facilitating the implementation of hybrid photon/confined-electron schemes for quantum communication and information processing.
Nonplasmonic surface enhanced Raman spectroscopy using silica microspheres
Authors: Anderson Mark S.
Published: October 2010

Surface enhanced Raman spectroscopy is presented using a nonplasmonic mechanism based on whispering gallery modes in silica microspheres. Sensitive Raman analysis of molecular films is demonstrated by using 5–10 μm sized silica spheres. The advantages of this nonplasmonic approach are the active substrate is chemically inert, thermally stable, and relatively simple to fabricate. Applications include trace organic analysis particularly for in situ planetary instruments that require robust sensors with consistent response.
Mechanically-exfoliated stacks of thin films of Bi2Te3 topological insulators with enhanced thermoelectric performance
Authors: Goyal V. , Teweldebrhan D. , Balandin A. A.
Published: October 2010

The authors report on “graphene-like” mechanical exfoliation of single-crystal Bi2Te3 films and thermoelectric characterization of the stacks of such films. Thermal conductivity of the resulting “pseudosuperlattices” was measured by the “hot disk” and “laser flash” techniques. The room temperature in-plane (cross-plane) thermal conductivity of the stacks decreases by a factor of ∼2.4 (3.5) as compared to bulk. The thermal conductivity reduction with preserved electrical properties leads to strong increase in the thermoelectric figure of merit. It is suggested that the film thinning to few-quintuples and tuning of the Fermi level can help in achieving the topological-insulator surface transport regime with an extraordinary thermoelectric efficiency.
Conformational studies of bottle-brush polymers absorbed on a flat solid surface
Authors: Hsu Hsiao-Ping , Paul Wolfgang , Binder Kurt
Published: October 2010

The adsorption of a bottle-brush polymer end-grafted with one chain end of its backbone to a flat substrate surface is studied by Monte Carlo simulation of a coarse-grained model, that previously has been characterized in the bulk, assuming a dilute solution under good solvent conditions. Applying the bond fluctuation model on the simple cubic lattice, we vary the backbone chain length Nb from Nb=67 to Nb=259 effective monomeric units, the side chain length N from N=6 to N=48, and set the grafting density to σ=1, i.e., parameters that correspond well to the experimentally accessible range. When the adsorption energy strength ϵ is varied, we find that the adsorption transition (which becomes well-defined in the limit Nb→∞, for arbitrary finite N) roughly occurs at the same value ϵc as for ordinary linear chains (N=0), at least within our statistical errors. Mean square end-to-end distances and gyration radii of the side chains are obtained, as well as the monomer density profile in the direction perpendicular to the adsorbing surface. We show that for longer side chains the adsorption of bottle-brushes is a two-step process, the decrease of the perpendicular linear dimension of side chains with adsorption energy strength can even be nonmonotonic. Also, the behavior of the static structure factor S(q) is analyzed, evidence for a quasi-two-dimensional scaling is presented, and consequences for the interpretation of experiments are discussed.
Reflective dual-mode liquid crystal display switchable between dynamic and memory modes
Authors: Lee Joong Ha , Kim Taehyung , Shin Hun Ki , Jhun Chul Gyu , Kwon Soon-Bum , Kim Dong-Guk , Kim Wook Sung , Yoon Tae-Hoon , Kim Jae Chang
Published: October 2010

This study proposes a reflective dual-mode liquid crystal display (RD-LCD) that can be operated in memory mode or dynamic mode according to the image contents. The proposed RD-LCD needs three states to represent dark and bright states, while a general reflective liquid crystal display has two states. Nevertheless, a compensation structure that can obtain high contrast ratios in both dynamic and memory modes has been optimized. The proposed RD-LCD can be operated without internal backlighting, thus making it a candidate for real green display.
Experimental demonstration of broadband transmission through subwavelength aperture
Authors: Bao Di , Rajab Khalid Z. , Tang Wenxuan , Hao Yang
Published: October 2010

Based on coordinate transformation techniques, a simplified all-dielectric extraordinary-transmission device for broadband transmission through a subwavelength aperture is verified experimentally in this paper. The device is made from isotropic dielectric blocks with permittivity values ranging from 2.1 to 6. It is shown both numerically and experimentally that the device can provide transmission with a −3 dB bandwidth of more than 1 GHz, in a region which would otherwise be a stop band caused by the subwavelength aperture in an X-band waveguide.
Effect of metal grain size on multiple microwave resonances of Fe/TiO2 metal-semiconductor composite
Authors: Zhang Qiang , Li Caifu , Chen Yanna , Han Zheng , Wang Han , Wang Zhanjie , Geng Dianyu , Liu Wei , Zhang Zhidong
Published: October 2010

The dielectric resonance and multiple magnetic resonances which correspond to multiple microwave absorptions in the 2–18 GHz range have been studied in the composite Fe/TiO2. The Fe grain size is found to have great impact on the dielectric resonance in this metal-semiconductor composite. The polarization mechanism is attributed to interfacial polarization. The multiple magnetic resonances can be ascribed to the natural resonance and exchange resonances, which can be explained by Aharoni’s exchange resonance theory.
Recombination dynamics in ZnO nanowires: Surfaces states versus mode quality factor
Authors: Reparaz J. S. , Güell F. , Wagner M. R. , Callsen G. , Kirste R. , Claramunt S. , Morante J. R. , Hoffmann A.
Published: October 2010

In this work, we investigate the influence of finite size on the recombinations dynamics of ZnO nanowires. We demonstrate that diameter as well as length of nanowires determine the lifetime of the neutral donor bound excitons. Our findings suggest that while the length is mainly responsible for different mode quality factors of the cavity-like nanowires, the diameter determines the influence of surface states as alternative recombinations channels for the optical modes trapped in the nanocavity. In addition, comparing nanowires grown using different catalyst we show that the surfaces states strongly depend on each precursor characteristics.
Contact resistance of flexible, transparent carbon nanotube films with metals
Authors: Xu Hua , Chen Lei , Hu Liangbing , Zhitenev Nikolai
Published: October 2010

We studied the contact properties of different metals to optically-transparent single-walled carbon nanotube (SWCNT) films using fabrication processes compatible with flexible electronic applications. The SWCNT films are deposited on flexible polyethylene terephthalate substrate and patterned in test structures optimized for contact resistance measurements for a particular metal contact. Specific contact resistance and current transfer length is determined for Pt, Cr, Cu, and Au contacts. We also evaluate effects of chemical doping and thickness of SWCNT films on the contact resistance. We find that the current transfer length, defining the minimal dimensions of efficient contacts to transparent SWCNT films, ranges from 8×10−6 to 10−4 m for different metals.
Generalized principle of corresponding states and the scale invariant mean-field approach
Authors: Bulavin L. A. , Kulinskii V. L.
Published: October 2010

In this paper we apply the relations between the critical points of the Lennard-Jones fluids and lattice gas model found in [V. L. Kulinskii, J. Phys. Chem. B 114, 2852 (2010)] to other short-ranged potentials like Buckingham and the Mie-potentials. The estimates for the corresponding critical point loci correlate quite satisfactory with the available numerical data for these potentials. The explanation for the correlation between the value of the second virial coefficient at the critical temperature and the particle volume found in [G. A. Vliegenthart and H. N. W. Lekkerkerker, J. Chem. Phys. 112, 5364 (2000)] is proposed. The connection of the stability of the liquid phase with the short range character of the potentials is discussed on the basis of the global isomorphism approach.
Watt level performance of quantum cascade lasers in room temperature continuous wave operation at λ∼3.76 μm
Authors: Bandyopadhyay N. , Bai Y. , Gokden B. , Myzaferi A. , Tsao S. , Slivken S. , Razeghi M.
Published: October 2010

An InP-based quantum cascade laser heterostructure emitting at 3.76 μm is grown with gas-source molecular beam epitaxy. The laser core is composed of strain balanced In0.76Ga0.24As/In0.26Al0.74As. Pulsed testing at room temperature exhibits a low threshold current density (1.5 kA/cm2) and high wall plug efficiency (10%). Room temperature continuous wave operation gives 6% wall plug efficiency with a maximum output power of 1.1 W. Continuous wave operation persists up to 95 °C.
Robustness and evolvability in the functional anatomy of a PER-ARNT-SIM (PAS) domain
Authors: Philip Andrew F. , Kumauchi Masato , Hoff Wouter D.
Published: October 2010

The robustness of proteins against point mutations implies that only a small subset of residues determines functional properties. We test this prediction using photoactive yellow protein (PYP), a 125-residue prototype of the PER-ARNT-SIM (PAS) domain superfamily of signaling proteins. PAS domains are defined by a small number of conserved residues of unknown function. We report high-throughput biophysical measurements on a complete Ala scan set of purified PYP mutants. The dataset of 1,193 values on active site properties, functional kinetics, stability, and production level reveals that 124 mutants retain the characteristic photocycle of PYP, but that the majority of substitutions significantly alter functional properties. Only 35% of substitutions that strongly affect function are located at the active site. Unexpectedly, most PAS-conserved residues are required for maintaining protein production. PAS domain activation often involves conformational changes in α-helices linked to the PAS core. However, the mechanism of transmission and kinetic regulation of allosteric structural changes from the PAS domain to these helices is not clear. The Ala scan data reveal interactions governing allosteric switching in PYP. The photocycle kinetics is significantly altered by substitutions at 58 positions and spans a 3,000-fold range. Nine residues that dock the N-terminal α-helices of PYP to its PAS core regulate signaling kinetics. Ile39 and Asn43 are identified as part of a mechanism for regulating allosteric switching that is conserved among PAS domains. These results show that PYP combines robustness with a high degree of evolvability and imply production level as an important factor in protein evolution.
Infection Prevention Research in Europe: Recent Advances and Future Priorities
Authors: Harbarth Stephan , Pittet Didier
Published: October 2010

During the past 2 decades, Europe has made substantial progress in the prevention and control of hospital-acquired infections and antimicrobial resistance (eg, through multicenter trials, international surveillance networks, and hand hygiene initiatives). This short overview highlights recent advances and future priorities in infection prevention research, including methodological challenges to be addressed.
The cosmopolitan maternal heritage of the Thoroughbred racehorse breed shows a significant contribution from British and Irish native mares
Authors: Bower M. A. , Campana M. G. , Whitten M. , Edwards C. J. , Jones H. , Barrett E. , Cassidy R. , Nisbet R. E. R. , Hill E. W. , Howe C. J. , Binns M.
Published: October 2010

The paternal origins of Thoroughbred racehorses trace back to a handful of Middle Eastern stallions, imported to the British Isles during the seventeenth century. Yet, few details of the foundation mares were recorded, in many cases not even their names (several different maternal lineages trace back to ‘A Royal Mare’). This has fuelled intense speculation over their origins. We examined mitochondrial DNA from 1929 horses to determine the origin of Thoroughbred foundation mares. There is no evidence to support exclusive Arab maternal origins as some historical records have suggested, or a significant importation of Oriental mares (the term used in historic records to refer to Middle East and western Asian breeds including Arab, Akhal-Teke, Barb and Caspian). Instead, we show that Thoroughbred foundation mares had a cosmopolitan European heritage with a far greater contribution from British and Irish Native mares than previously recognized.
Paenibacillus algorifonticola sp. nov., isolated from a cold spring
Authors: Tang Qi-Yong , Yang Na , Wang Jian , Xie Yu-Qing , Ren Biao , Zhou Yu-Guang , Gu Mei-Ying , Mao Jun , Li Wen-Jun , Shi Yu-Hu , Zhang Li-Xin
Published: October 2010

A Gram-stain-positive, endospore-forming, rod-shaped bacterium, designated XJ259T, was isolated from a cold spring sample from Xinjiang Uyghur Autonomous Region, China. The isolate grew optimally at 20–30 °C and pH 7.3–7.8. Comparative analysis of the 16S rRNA gene sequence showed that isolate XJ259Tbelonged phylogenetically to the genusPaenibacillus, and was most closely related toPaenibacillus xinjiangensisB538T(with 96.6 % sequence similarity),Paenibacillus glycanilyticusDS-1T(96.3 %) andPaenibacillus castaneaeCh-32T(96.1 %), sharing less than 96.0 % sequence similarity with all other members of the genusPaenibacillus. Chemotaxonomic analysis revealing menaquinone-7 (MK-7) as the major isoprenoid quinone, diphosphatidylglycerol, phosphatidylethanolamine and two unknown phosphoglycolipids as the major cellular polar lipids, a DNA G+C content of 47.0 mol%, and anteiso-C15 : 0and C16 : 0as the major fatty acids supported affiliation of the new isolate to the genusPaenibacillus. Based on these data, isolate XJ259Tis considered to represent a novel species of the genusPaenibacillus, for which the namePaenibacillus algorifonticolasp. nov. is proposed. The type strain is XJ259T( = CGMCC 1.10223T = JCM 16598T).
Isolation and characterization of Reyranella massiliensis gen. nov., sp. nov. from freshwater samples by using an amoeba co-culture procedure
Authors: Pagnier Isabelle , Raoult Didier , La Scola Bernard
Published: October 2010

The analysis of three water samples from two cooling towers and one river allowed us to isolate three strains of a novel species of the classAlphaproteobacteriawhich is phylogenetically related to uncultured alphaproteobacteria. Based upon 16S rRNA gene sequence analysis and phenotypic characterization, we propose to name this novel speciesReyranella massiliensisgen. nov., sp. nov., type strain 521T( = CSUR P115T = DSM 23428T). The most closely related cultivable micro-organism to this novel bacterium is a member of the genusMagnetospirillum.
A Novel Factor FLOURY ENDOSPERM2 Is Involved in Regulation of Rice Grain Size and Starch Quality
Authors: She Kao-Chih , Kusano Hiroaki , Koizumi Kazuyoshi , Yamakawa Hiromoto , Hakata Makoto , Imamura Tomohiro , Fukuda Masato , Naito Natsuka , Tsurumaki Yumi , Yaeshima Mitsuhiro , Tsuge Tomohiko , Matsumoto Ken'ichiro , Kudoh Mari , Itoh Eiko , Kikuchi Shoshi , Kishimoto Naoki , Yazaki Junshi , Ando Tsuyu , Yano Masahiro , Aoyama Takashi , Sasaki Tadamasa , Satoh Hikaru , Shimada Hiroaki
Published: October 2010

Rice (Oryza sativa) endosperm accumulates a massive amount of storage starch and storage proteins during seed development. However, little is known about the regulatory system involved in the production of storage substances. The rice flo2 mutation resulted in reduced grain size and starch quality. Map-based cloning identified FLOURY ENDOSPERM2 (FLO2), a member of a novel gene family conserved in plants, as the gene responsible for the rice flo2 mutation. FLO2 harbors a tetratricopeptide repeat motif, considered to mediate a protein–protein interactions. FLO2 was abundantly expressed in developing seeds coincident with production of storage starch and protein, as well as in leaves, while abundant expression of its homologs was observed only in leaves. The flo2 mutation decreased expression of genes involved in production of storage starch and storage proteins in the endosperm. Differences between cultivars in their responsiveness of FLO2 expression during high-temperature stress indicated that FLO2 may be involved in heat tolerance during seed development. Overexpression of FLO2 enlarged the size of grains significantly. These results suggest that FLO2 plays a pivotal regulatory role in rice grain size and starch quality by affecting storage substance accumulation in the endosperm.
Provitamin A Accumulation in Cassava (Manihot esculenta) Roots Driven by a Single Nucleotide Polymorphism in a Phytoene Synthase Gene
Authors: Welsch Ralf , Arango Jacobo , Bär Cornelia , Salazar Bertha , Al-Babili Salim , Beltrán Jesús , Chavarriaga Paul , Ceballos Hernan , Tohme Joe , Beyer Peter
Published: October 2010

Cassava (Manihot esculenta) is an important staple crop, especially in the arid tropics. Because roots of commercial cassava cultivars contain a limited amount of provitamin A carotenoids, both conventional breeding and genetic modification are being applied to increase their production and accumulation to fight vitamin A deficiency disorders. We show here that an allelic polymorphism in one of the two expressed phytoene synthase (PSY) genes is capable of enhancing the flux of carbon through carotenogenesis, thus leading to the accumulation of colored provitamin A carotenoids in storage roots. A single nucleotide polymorphism present only in yellow-rooted cultivars cosegregates with colored roots in a breeding pedigree. The resulting amino acid exchange in a highly conserved region of PSY provides increased catalytic activity in vitro and is able to increase carotenoid production in recombinant yeast and Escherichia coli cells. Consequently, cassava plants overexpressing a PSY transgene produce yellow-fleshed, high-carotenoid roots. This newly characterized PSY allele provides means to improve cassava provitamin A content in cassava roots through both breeding and genetic modification.
In vitro release kinetics of pine bark extract enriched orange juice and the shelf stability
Authors: Yesil Celiktas Ozlem , Isleten Muge , Vardar‐Sukan Fazilet , Oyku Cetin E.
Published: October 2010

Purpose

This paper seeks to demonstrate a functional beverage incorporating pine bark which is an unutilized forestry waste, determine in vitro release kinetics of enriched beverages, and antioxidant activities, besides assessing their shelf stabilities.

Design/methodology/approach

Orange juice was enriched with Pinus brutia, Pinus pinea bark extracts, Pycnogenol®. In vitro release kinetics was determined in pH 1.2 and pH 7.4. Ascorbic acid content, pH, titratable acidity, and colorimetric analyses were analyzed monthly for eight months to determine shelf life. Additionally, total phenol contents and radical scavenging activities were analyzed. Subsequently a consumer acceptance test was conducted among 200 participants.

Findings

The release of all extracts in orange juices in pH 1.2 were slower than pH 7.4. The release results were fitted to Higuchi square root of time kinetic model with high determination coefficients. Although total titratable acidity values were in agreement with the trend of minor pH changes, prominent losses in antioxidant capacities, ascorbic acid contents and color were observed for the last two months suggesting a shelf life of six months. Female participants and young people had a greater tendency to consume such a beverage. Health concerns and flavor were the primary factors affecting their purchasing decisions.

Research limitations/implications

Findings of the study demonstrated the effects of fortification with a plant‐based extract as a substitute to the present practice of fortifying beverages with vitamins and minerals for a potential future market.

Originality/value

The paper shows that juices fortified with pine bark extracts show higher antioxidant capacities and ascorbic acid contents compared to the control, thereby providing improved functionality.
A tale of two crises: the Belgian and Irish dioxin contamination incidents
Authors: Casey Donal K. , Lawless James S. , Wall Patrick G.
Published: October 2010

Purpose

This paper aims to provide a focused overview of two dioxin incidents, with particular emphasis on regulatory successes and failures and their respective causes. The paper seeks to adopt a comparative approach to the case studies, with considerable use made of primary sources such as parliamentary debate, government reports and EC legislation.

Design/methodology/approach

The paper is a review of the strengths and weaknesses in the management of the Belgian and Irish dioxin contanimation incidents.

Findings

It is concluded that open, transparent and decisive risk management, based on robust risk assessment, is paramount in ensuring confidence in both the food supply chain and, in the feed and food safety regulatory process. It is also concluded that the 2008 Irish dioxin incident tested the reforms prompted by previous food scares.

Practical implications

It is important that the lessons from these two incidents are learnt if they are not to be repeated in other jurisdictions.

Originality/value

This is the first academic study of the 2008 Irish dioxin incident, one of the most significant recent food scares in the European Communities. The incident emphasises the vital role of open, transparent and decisive decision making in managing risk. In addition, through a comparative analysis of the Belgian and Irish incidents, the utility of the reforms prompted by previous food scares is demonstrated. In particular, the study highlights the important role played by the European Food Safety Authority in one of its first major tests as a risk assessor and risk communicator.