bluuebunny/crossref_metadata_2025 huggingface dataset:
Iterative source and channel decoding relying on correlation modelling for wireless video transmission
Authors: Huo Yongkai , Wang Tao , Maunder Robert G. , Hanzo Lajos
Published: September 2013

Since joint source‐channel decoding is capable of exploiting the residual redundancy in the source signals for improving the attainable error resilience, it has attracted substantial attention. In this treatise, the authors study iterative source‐channel decoding (ISCD) aided video communications, where the video signal redundancy is modelled by a first‐order Markov process. Firstly, the authors derive reduced‐complexity formulas for the first‐order Markov modelling (FOMM) aided source decoding. Then they propose a bit‐based iterative horizontal–vertical scanline model (IHVSM) aided source decoding algorithm, where a horizontal and a vertical source decoder are employed for exchanging their extrinsic information using the iterative decoding philosophy. The iterative IHVSM aided decoder is then employed in a forward error correction (FEC) encoded uncompressed video transmission scenario, where the IHVSM and the FEC decoder exchange softbit‐information for performing turbo‐like ISCD for the sake of improving the reconstructed video quality. Finally, the authors benchmark the attainable system performance against a near‐lossless H.264/AVC video communication system and the existing FOMM‐based softbit source decoding scheme. The authors simulation results show that Eb/N0 improvements in excess of 2.8 dB are attainable by the proposed technique in uncompressed video applications.
Low‐contrast satellite images enhancement using discrete cosine transform pyramid and singular value decomposition
Authors: Atta Randa , Ghanbari Mohammad
Published: September 2013

This study presents a satellite image contrast enhancement technique based on the discrete cosine transform (DCT) pyramid and singular value decomposition (SVD), in contrast to the methods based on wavelet decomposition and SVD which could fail to produce satisfactory results for some low‐contrast images. With the proposed method, an input image is decomposed into a low sub‐band image and reversed L‐shape blocks containing the high‐frequency coefficients of the DCT pyramid. The singular value matrix of the equalised low sub‐band image is then estimated from the combination between the singular matrix of the low sub‐band image and the singular matrix of its global histogram equalisation. The qualitative and quantitative performances of the proposed technique are compared with those of conventional image equalisation such as general histogram equalisation and local histogram equalisation, as well as some state‐of‐the‐art techniques such as singular value equalisation technique. Moreover, the proposed technique is contrasted against the technique based on the discrete wavelet transform (DWT) and SVD (DWT–SVD) as well as the technique based on DCT–SVD. The experimental results show that the proposed method outperforms both conventional and the state‐of‐the‐art techniques.
Image denoising algorithm based on contourlet transform for optical coherence tomography heart tube image
Authors: Guo Qing , Dong Fangmin , Sun Shuifa , Lei Bangjun , Gao Bruce Z.
Published: September 2013

Optical coherence tomography (OCT) is becoming an increasingly important imaging technology in the Biomedical field. However, the application of OCT is limited by the ubiquitous noise. In this study, the noise of OCT heart tube image is first verified as being multiplicative based on the local statistics (i.e. the linear relationship between the mean and the standard deviation of certain flat area). The variance of the noise is evaluated in log‐domain. Based on these, a joint probability density function is constructed to take the inter‐direction dependency in the contourlet domain from the logarithmic transformed image into account. Then, a bivariate shrinkage function is derived to denoise the image by the maximum a posteriori estimation. Systemic comparative experiments are made to synthesis images, OCT heart tube images and other OCT tissue images by subjective assessment and objective metrics. The experiment results are analysed based on the denoising results and the predominance degree of the proposed algorithm with respect to the wavelet‐based algorithm. The results show that the proposed algorithm improves the signal‐to‐noise ratio, whereas preserving the edges and has more advantages on the images containing multi‐direction information like OCT heart tube image.
Inkjet printed SU‐8 hemispherical microcapsules and silicon chip embedding
Authors: Jacot‐Descombes Loïc , Gullo Maurizio Rosario , Mastrangeli Massimo , Cadarso Victor Javier , Brugger Jürgen
Published: September 2013

Planar lithography techniques are not effective for precise fabrication of microdevices with hemispherical shapes. Drop‐on‐demand (DOD) inkjet printing (IJP) of photo‐curable ink is a more appropriate fabrication approach as it takes advantage of the surface tension as well as of the delivery of a well‐defined ink volume. Described is a DOD IJP technique onto geometrically‐patterned silicon substrates enabling the controlled fabrication of SU‐8 hemispherical microcapsules. Open half capsules of 100 µm in diameter with inner cavity volumes of 5, 20 and 45 pl with a printing yield above 96% are demonstrated. The same technique is directly adapted to the fabrication of microcapsules embedding silicon microchips. The reported findings open new paths for controlled encapsulation of liquids into smart microsystems.
Fabrication of sub‐wavelength structures on silicon dioxide
Authors: Huang Mao‐Jung , Tang Yu‐Hsiang , Su Jien‐Yin , Chu Nien‐Nan , Shiao Ming‐Hua , Hsiao Chien‐Nan
Published: September 2013

In this reported work, nanosphere lithography (NSL) and inductively coupled plasma reactive ion etching (ICP‐RIE) are combined to successfully fabricate a sub‐wavelength structure (SWS) on a glass substrate, achieving broadband antireflection and increasing the transmittance of incident light through the glass. The experimental results show that the SWS surfaces with 180 nm width and 50 nm height could be fabricated onto glass. The mean reflectance of a blank glass is 5.81% in the wavelength range of 400–950 nm, 3 min of ICP‐RIE combined with NSL reduce the mean reflectance to 3.5% and increases the mean transmittance from 92.3 to 94.3%. An additional coat of a 200 Å‐thick gold layer on the 30 s etched surface sample reduces the transmittance in the visible light range (400–700 nm) to 36.6%, which is 2.25 times larger than that at the infrared range (700–950 nm). The proposed novel fabrication technology has the advantage of being low cost, and the fabricated nanodot array structure, which is gold coated, can be used on an insulated window.
Analytical studies on amplitude change enhancement in coupled aluminium nitride coated single crystal silicon oscillator pair applicable to ultra‐sensitive resonating microfluidic flowmeters
Authors: Wang Dong F. , Chatani Keisuke , Kozuka Kenji , Ikehara Tsuyoshi , Maeda Ryutaro
Published: September 2013

The use of vibration mode localisation in arrays of micromechanically coupled, nearly identical beam‐shaped resonators has been analytically studied for ultra‐sensitive resonating‐based flowmeters. Eigenstate shifts (amplitude change in this Letter) that are about two times (compared with the single resonator), and orders (compared with the resonator array) of magnitude greater than corresponding shifts in resonant frequency for an induced fluid flow (corresponding to an induced small mass perturbation) are preliminarily obtained by theoretical analysis. When an external force of 100 Pa, corresponding to an estimated fluid flow velocity of about 3.15 m/s, is applied to any one (because of the symmetrical design) of the two coupled aluminium nitride coated single crystal silicon resonators, two orders of the amplitude enhancement can be observed for both the resonators at the higher (second) resonance frequency because of vibration mode localisation, which implies the application possibility to highly sensitive resonating‐based flow sensors.
How rotational vortices enhance transfers
Authors: Griffani D. , Rognon P. , Metzger B. , Einav I.
Published: September 2013

Inspired by recent observations of granular flow, we examine how rotational vortices contribute to heat or mass transfer enhancement in a fluid. We use a tracer method to simulate both diffusion and advection in systems of differing intrinsic diffusivities D0, vortex sizes R, vortex rotation frequencies f, and vortex lifetimes ℓ. The results reveal that these systems exhibit an effective diffusive behavior, characterized by an effective diffusivity Deff. A striking finding is the existence of two regimes, dichotomised by the Péclet number Pe = R2f/D0. When the Péclet number is less than one, there is no transfer enhancement, Deff = D0. For higher values, vortices produce some transfer enhancement with a corresponding power law Deff/D0 ≈ Pen. The power n ranges from a lower bound of 0.5 for stationary vortices of lifetime infinity, to an upper bound of 1 for vortices of lifetimes shorter than half a rotation. This difference is attributed to two different internal mechanisms involving the coupling of diffusion and advection. These results could provide new insights on the transfer properties of fluid systems comprising rotational vortices, such as granular materials, suspensions, foams, and emulsions, as well as low Reynolds number stirred flows.
Robust fitting techniques in the chain of spheres approximation to the Fock exchange: The role of the complementary space
Authors: Izsák Róbert , Neese Frank , Klopper Wim
Published: September 2013

The chain of spheres seminumerical integration algorithm is reexamined from the point of view of various numerical error cancellation schemes. The two sources of ideas are the robust fitting technique of Dunlap and the dealiasing concept of the pseudospectral methods of Friesner. The most efficient scheme is identified and is found to be a generalization of the overlap fitting procedure discussed earlier. It will be shown that due to the conceptual similarity between complementary auxiliary basis functions of explicitly correlated approaches and the dealiasing functions of pseudospectral methods, the former can be used in a similar manner as the latter to cancel numerical errors. In contrast to the dealiasing functions, the complementary auxiliary basis functions are not specific to the integration grid. The scheme obtained can dramatically improve reaction energies even using small grid setups at a moderate additional cost.
Molecular dynamics simulation of shock melting of aluminum single crystal
Authors: Ju Yuanyuan , Zhang Qingming , Gong Zizheng , Ji Guangfu , Zhou Lin
Published: September 2013

Molecular dynamics method in conjunction with multi-scale shock technique is employed to study the melting characteristics of aluminum single crystal under dynamic conditions. The simulated results show that a linear relationship exists between the shock wave velocity and particle velocity, in good agreement with the experimental data. Comparing the Lindemann melting curve with the two Hugoniot curves for the solid and liquid phases, the Hugoniot melting is found to begin at 93.6 GPa and end at 140 GPa, which is consistent with the theoretical calculations. The impact of crystal defects on the melting characteristics of aluminum single crystal is also studied, and the results indicate that the pressure and temperature increase slightly for the system experiencing the same dynamic loading due to the crystal defects.
Study of vortex-shedding-induced vibration of a flexible splitter plate behind a cylinder
Authors: Lee Jinmo , You Donghyun
Published: September 2013

A computational analysis of vortex-shedding-induced vibration of a flexible splitter plate behind a cylinder at a low Reynolds number is conducted to understand effects of the length and flexibility of a splitter plate on the drag and lift of a cylinder and vibration of the attached plate. The drag and lift coefficients, the Strouhal number of vortex shedding, and the magnitude of tip displacements of a flexible splitter plate are found to be intricate functions of the plate flexibility. The deflection shape of a flexible splitter plate is dependent on the length of the plate, while the deflection magnitude is a function of the bending stiffness and natural frequencies of the corresponding plate. It is concluded in the present work that the Strouhal number of vortex shedding or the frequency of plate deflection is difficult to estimate using natural frequencies of the plate, which are calculated by inducing free vibration, since the fluid loading is distributed non-uniformly over the plate rather than concentrated at the tip of the plate. The present study suggests that the flexibility of a splitter plate, in general, adversely modulates the drag and lift forces acting on the cylinder surface while it promotes the oscillation of the plate.
An efficient linear-scaling CCSD(T) method based on local natural orbitals
Authors: Rolik Zoltán , Szegedy Lóránt , Ladjánszki István , Ladóczki Bence , Kállay Mihály
Published: September 2013

An improved version of our general-order local coupled-cluster (CC) approach [Z. Rolik and M. Kállay, J. Chem. Phys. 135, 104111 (2011)]10.1063/1.3632085 and its efficient implementation at the CC singles and doubles with perturbative triples [CCSD(T)] level is presented. The method combines the cluster-in-molecule approach of Li and co-workers [J. Chem. Phys. 131, 114109 (2009)]10.1063/1.3218842 with frozen natural orbital (NO) techniques. To break down the unfavorable fifth-power scaling of our original approach a two-level domain construction algorithm has been developed. First, an extended domain of localized molecular orbitals (LMOs) is assembled based on the spatial distance of the orbitals. The necessary integrals are evaluated and transformed in these domains invoking the density fitting approximation. In the second step, for each occupied LMO of the extended domain a local subspace of occupied and virtual orbitals is constructed including approximate second-order Møller–Plesset NOs. The CC equations are solved and the perturbative corrections are calculated in the local subspace for each occupied LMO using a highly-efficient CCSD(T) code, which was optimized for the typical sizes of the local subspaces. The total correlation energy is evaluated as the sum of the individual contributions. The computation time of our approach scales linearly with the system size, while its memory and disk space requirements are independent thereof. Test calculations demonstrate that currently our method is one of the most efficient local CCSD(T) approaches and can be routinely applied to molecules of up to 100 atoms with reasonable basis sets.
Modulation of peak-to-valley current ratio of Coulomb blockade oscillations in Si single hole transistors
Authors: Lee Sejoon , Lee Youngmin , Song Emil B. , Hiramoto Toshiro
Published: September 2013

We demonstrate a method to modulate the peak-to-valley current ratio of Coulomb blockade oscillation peaks in room temperature-operating Si single-hole tunnel transistors. By connecting the extra p+in+ junction (i.e., a current effluence path) to the drain reservoir, we effectively deplete the leakage current (i.e., valley current) that stem from the diffusion current of the parasitic field-effect transistor within the device. The addition of the extra current-effluence path significantly improves the Coulomb blockade characteristics in comparison to the original Coulomb blockade oscillations. We believe the method is advantageous for designing high performance Si single electron/hole tunnel devices.
Electrostatic forces in the Poisson-Boltzmann systems
Authors: Xiao Li , Cai Qin , Ye Xiang , Wang Jun , Luo Ray
Published: September 2013

Continuum modeling of electrostatic interactions based upon numerical solutions of the Poisson-Boltzmann equation has been widely used in structural and functional analyses of biomolecules. A limitation of the numerical strategies is that it is conceptually difficult to incorporate these types of models into molecular mechanics simulations, mainly because of the issue in assigning atomic forces. In this theoretical study, we first derived the Maxwell stress tensor for molecular systems obeying the full nonlinear Poisson-Boltzmann equation. We further derived formulations of analytical electrostatic forces given the Maxwell stress tensor and discussed the relations of the formulations with those published in the literature. We showed that the formulations derived from the Maxwell stress tensor require a weaker condition for its validity, applicable to nonlinear Poisson-Boltzmann systems with a finite number of singularities such as atomic point charges and the existence of discontinuous dielectric as in the widely used classical piece-wise constant dielectric models.
Isotropic magnetic shielding constants of retinal derivatives in aprotic and protic solvents
Authors: Colherinhas G. , Fonseca T. L. , Castro M. A. , Coutinho K. , Canuto S.
Published: September 2013

We investigate the nuclear isotropic shielding constants σ(13C) and σ(17O) of isomers of retinoic acid and retinal in gas-phase and in chloroform, acetonitrile, methanol, and water solutions via Monte Carlo simulation and quantum mechanics calculations using the GIAO-B3LYP/6-311++G(2d,2p) approach. Electronic solute polarization effects due to protic and aprotic solvents are included iteratively and play an important role in the quantitative determination of oxygen shielding constants. Our MP2/6-31G+(d) results show substantial increases of the dipole moment of both retinal derivatives in solution as compared with the gas-phase results (between 22% and 26% in chloroform and between 55% and 99% in water). For the oxygen atoms the influence of the solute polarization is mild for σ(17O) of hydroxyl group, even in protic solvents, but it is particularly important for σ(17O) of carbonyl group. For the latter, there is a sizable increase in the magnitude with increasing solvent polarity. For the carbon atoms, the solvent effects on the σ(13C) values are in general small, being more appreciable in carbon atoms of the polyene chain than in the carbon atoms of the β-ionone ring and methyl groups. The results also show that isomeric changes on the backbones of the polyene chains have marked influence on the 13C chemical shifts of carbon atoms near to the structural distortions, in good agreement with the experimental results measured in solution.
Numerical simulations of the alternating current loss in round high-temperature superconducting wire with a hole defect
Authors: Xia Jing , Yong Huadong , Zhou Youhe
Published: September 2013

This paper presents a finite element model to solve the electromagnetic behavior and the AC loss in round high-temperature superconducting wire with a hole defect both in external field condition and self-field condition. The hole defect is assumed to be infinitely long along the wire. The model is based on the H formulation and the highly nonlinear E−J characteristic. The simulation results for the round superconducting wire with a hole defect and the one without defect are compared. It is found that the existence of the hole defect causes small reduction for the magnetization AC loss and large enhancement for the transport AC loss. The influences of the position and shape of the hole on the AC loss are also investigated. We find that the AC loss in external field condition decreases when the hole defect moves towards the edge of the superconducting wire from its center. However, the feature is opposite in self-field condition. Meanwhile, the influence of the shape of the hole on the AC loss is not strong in both conditions.
Subgrid-scale eddy viscosity model for helical turbulence
Authors: Yu Changping , Hong Renkai , Xiao Zuoli , Chen Shiyi
Published: September 2013

A novel eddy-viscosity closure is proposed for the subgrid-scale (SGS) stress tensor in large-eddy simulation of helical turbulence. The eddy-viscosity is shown to be proportional to the product of the large-scale velocity strain rate tensor and the symmetric part of the large-scale vorticity gradient (or vorticity strain rate tensor) based on a SGS helicity dissipation balance and a spectral relative helicity relation. The new SGS model is first tested and validated in simulation of homogeneous and isotropic helical turbulence. The statistical results demonstrate that the present model can predict both the energy and helicity spectra more precisely than the dynamic Smagorinsky model and a mixed helical model as compared with the results calculated in direct numerical simulation. Then, a compressible version of the new SGS model is parameterized and utilized to simulate the compressible flow past a circular cylinder. It is found that the present eddy-viscosity model can reproduce the skin friction force much more accurately than the standard Smagorinsky model, and can simulate more realistic flow structures in the near wake of the cylinder than the detached-eddy simulation approach. The surprising findings in simulation of flow past a circular cylinder suggest that the inclusion of contribution from helicity in SGS modeling is important for large-eddy simulation of separated turbulent flows.
Tuning the Curie temperature of FeCo compounds by tetragonal distortion
Authors: Jakobsson A. , Şaşıoğlu E. , Mavropoulos Ph. , Ležaić M. , Sanyal B. , Bihlmayer G. , Blügel S.
Published: September 2013

Combining density-functional theory calculations with a classical Monte Carlo method, we show that for B2-type FeCo compounds, tetragonal distortion gives rise to a strong reduction of the Curie temperature TC. The TC monotonically decreases from 1575 K (for c/a=1) to 940 K (for c/a=2). We find that the nearest neighbor Fe-Co exchange interaction is sufficient to explain the c/a behavior of the TC. Combination of high magnetocrystalline anisotropy energy with a moderate TC value suggests tetragonal FeCo grown on the Rh substrate with c/a=1.24 to be a promising material for heat-assisted magnetic recording applications.
Three-dimensional flow features in a nominally two-dimensional rectangular cavity
Authors: Di Cicca G. M. , Martinez M. , Haigermoser C. , Onorato M.
Published: September 2013

The object of the present paper was to look at the three-dimensional features of a flow in a nominally two-dimensional rectangular cavity having the length-to-depth ratio equal to 3, with laminar incoming boundary layer. The motivation was to give a contribution to the understanding of the origin of the spanwise flow structures observed in cavity flows. Particle image velocimetry was used to highlight the flow structure at low Reynolds number in the plane parallel to the cavity external flow and normal to the cavity bottom (vertical plane) and in planes parallel to cavity bottom (horizontal planes). The results demonstrate that the present measurements are qualitatively and quantitatively in agreement with published studies having as object the observation of the cavity flow behavior in the vertical plane, assuming the cavity to be nominally two-dimensional. Results in the planes parallel to the cavity bottom show the three-dimensional nature of the flow, characterized by the discontinuous presence of jet-like flows directed towards the cavity leading edge and towards the cavity trailing edge. The origin and nature of these discontinuous “jets” are examined and discussed in the paper. The flow structures are characterized by a wavelength scaling with the cavity length in proximity of the leading edge and with the cavity depth in the region of the trailing edge. Isolated three-dimensional flow structures consisting of side by side counter-rotating vortices have been also observed in the horizontal planes and tentatively interpreted as secondary flows induced by the instability of the main recirculation bubble.
Solid-liquid coexistence in small systems: A statistical method to calculate melting temperatures
Authors: Hong Qi-Jun , van de Walle Axel
Published: September 2013

We propose an efficient and accurate scheme to calculate the melting point (MP) of materials. This method is based on the statistical analysis of small-size coexistence molecular dynamics simulations. It eliminates the risk of metastable superheated solid in the fast-heating method, while also significantly reducing the computer cost relative to the traditional large-scale coexistence method. Using empirical potentials, we validate the method and systematically study the finite-size effect on the calculated MPs. The method converges to the exact result in the limit of large system size. An accuracy within 100 K in MP is usually achieved when simulation contains more than 100 atoms. Density functional theory examples of tantalum, high-pressure sodium, and ionic material NaCl are shown to demonstrate the accuracy and flexibility of the method in its practical applications. The method serves as a promising approach for large-scale automated material screening in which the MP is a design criterion.
Temperature and density evolution during decay in a 2.45 GHz hydrogen electron cyclotron resonance plasma: Off-resonant and resonant cases
Authors: Cortázar O. D. , Megía-Macías A. , Vizcaíno-de-Julián A.
Published: September 2013

Time resolved electron temperature and density measurements during the decay stage in a hydrogen electron cyclotron resonance (ECR) plasma are presented for a resonance and off-resonance magnetic field configurations. The measurements are conducted on a ECR plasma generator excited at 2.45 GHz denominated test-bench for ion-sources plasma studies at ESS Bilbao. The plasma parameters evolution is studied by Langmuir probe diagnostic with synchronized sample technique developed for repetitive pulsed plasmas with a temporal resolution of 200 ns in typical decay processes of about 40 μs. An afterglow transient is clearly observed in the reflected microwave power signal from the plasma. Simultaneously, the electron temperature evolution shows rebounding peaks that may be related to the interplay between density drop and microwave coupling with deep impact on the Electron Energy Distribution Function. The correlation of such structures with the plasma absorbed power and the coupling quality is also reported.
Note: Homogeneous TIP4P/2005 ice nucleation at low supercooling
Authors: Reinhardt Aleks , Doye Jonathan P. K.
Published: September 2013

We present a partial free energy profile for the homogeneous nucleation of ice using an all-atom model of water at low supercooling, at which ice growth dynamics are reasonably accessible to simulation. We demonstrate that the free energy profile is well described by classical nucleation theory, and that the nucleation barrier is entropic in origin. We also estimate to first order the temperature dependence of the interfacial free energy.
Deposition temperature independent excellent passivation of highly boron doped silicon emitters by thermal atomic layer deposited Al2O3
Authors: Liao Baochen , Stangl Rolf , Ma Fajun , Hameiri Ziv , Mueller Thomas , Chi Dongzhi , Aberle Armin G. , Bhatia Charanjit S. , Hoex Bram
Published: September 2013

In this work, we demonstrate that by using H2O based thermal atomic layer deposited (ALD) Al2O3 films, excellent passivation (emitter saturation current density of ∼28 fA/cm2) on industrial highly boron p+-doped silicon emitters (sheet resistance of ∼62 Ω/sq) can be achieved. The surface passivation of the Al2O3 film is activated by a fast industrial high-temperature firing step identical to the one used for screen printed contact formation. Deposition temperatures in the range of 100-300 °C and peak firing temperatures of ∼800 °C (set temperature) are investigated, using commercial-grade 5″ Cz silicon wafers (∼5 Ω cm n-type). It is found that the level of surface passivation after activation is excellent for the whole investigated deposition temperature range. These results are explained by advanced computer simulations indicating that the obtained emitter saturation current densities are quite close to their intrinsic limit value where the emitter saturation current is solely ruled by Auger recombination. The process developed is industrially relevant and robust.
Extremely large magnetoresistance induced by optical irradiation in the Fe/SiO2/p-Si hybrid structure with Schottky barrier
Authors: Volkov N. V. , Tarasov A. S. , Eremin E. V. , Baron F. A. , Varnakov S. N. , Ovchinnikov S. G.
Published: September 2013

We report giant magnetoresistance (MR) effect that appears under the influence of optical radiation in common planar device built on Fe/SiO2/p-Si hybrid structure. Our device is made of two Schottky diodes connected to each other by the silicon substrate. Photo-induced MR is positive and the MR ratio reaches the values in excess of 104%. The main peculiarity of the MR behavior is its strong dependence on the magnitude and the sign of the bias current across the device and, most surprisingly, upon polarity of the magnetic field. To explain such unexpected behavior of the MR, one needs to take into account contribution of several physical mechanisms. The main contribution comes from the existence of localized interface states at the SiO2/p-Si interface, which provide the spots for the photo-current conduction by virtue of the sequential tunneling through them or thermal generation and optical excitation of mobile charges. External magnetic field changes the probability of these processes due to its effect on the energy states of the conduction centers. Two possible mechanisms that may be responsible for the observed dependence of magneto-resistance on the field polarity are discussed: the effect of the Lorentz force on moving carriers and spin splitting of electrons moving in the electrostatic potential gradient (Rashba effect). The most significant observation, in our opinion, is that the observed MR effect is seen exclusively in the subsystem of minority carriers transferred into non-equilibrium state by optical excitation. We suggest that building such magneto-sensitive devices based on this mechanism may set a stage for new types of spintronic devices to emerge.
Electro-osmotic flow of semidilute polyelectrolyte solutions
Authors: Uematsu Yuki , Araki Takeaki
Published: September 2013

We investigate electro-osmosis in aqueous solutions of polyelectrolytes using mean-field equations. A solution of positively charged polyelectrolytes is confined between two negatively charged planar surfaces, and an electric field is applied parallel to the surfaces. When electrostatic attraction between the polymer and the surface is strong, the polymers adhere to the surface, forming a highly viscous adsorption layer that greatly suppresses the electro-osmosis. Conversely, electro-osmosis is enhanced by depleting the polymers from the surfaces. We also found that the electro-osmotic flow is invertible when the electrostatic potential decays to its bulk value with the opposite sign. These behaviors are well explained by a simple mathematical form of the electro-osmotic coefficient.
Driving the magnetization reversal below the blocking temperature in exchange biased NiFe/NiO
Authors: Dekadjevi D. T. , Prinsloo A. R. E. , Carleschi E. , Richy J. , Legraet C. , Pogossian S. P. , Jay J.-Ph. , Spenato D. , Ben Youssef J. , Strydom A. M.
Published: September 2013

The temperature dependence of the exchange bias field and coercive field was studied in a polycrystalline NiFe layer coupled with a diluted NiO layer. The temperature behavior of both fields is modified by cooling the bilayer below the Curie, Neel, and/or blocking temperatures. Below these temperatures, the presence of double hysteresis loops demonstrates the key role of the NiFe multidomain state during the cooling procedure.
Atomistic simulation for the size effect on the mechanical properties of Ni/Ni3Al nanowire
Authors: Yang Xiyuan , Xiao Shifang , Hu Wangyu
Published: September 2013

The size dependence of the mechanical properties of Ni/Ni3Al nanowires (NWs) was investigated with molecular dynamics (MD) simulations. The results indicated that the surface energy σ increased, and bulk modulus B and B/G ratio decreased with increasing the inverse of the nanowire perimeter of the NWs. The extrapolated values of surface energy σ0 were 2.100 J/m2 and 1.956 J/m2 for the samples with surface atoms of pure Ni atoms and mixture of Ni and Al atoms, respectively. The size dependence of the bulk modulus was in good agreement with the prediction of the Birch-Murnaghan equation and the surface shell softening the bulk modulus. Finally, the B/G ratio indicated that the ductility/brittleness behaviors of the NWs depended mainly on the energy distributions of the surface shell, and the mechanisms of the ductility/brittleness of the NWs were studied in detail.
High-resolution full-field spatial coherence gated optical tomography using monochromatic light source
Authors: Srivastava Vishal , Nandy Sreyankar , Singh Mehta Dalip
Published: September 2013

We demonstrate dispersion free, high-resolution full-field spatial coherence gated optical tomography using spatially incoherent monochromatic light source. Spatial coherence properties of light source were synthesized by means of combining a static diffuser and vibrating multi mode fiber bundle. Due to low spatial coherence of light source, the axial resolution of the system was achieved similar to that of conventional optical coherence tomography which utilizes low temporal coherence. Experimental results of fringe visibility versus optical path difference are presented for varying numerical apertures objective lenses. High resolution optically sectioned images of multilayer onion skin, and red blood cells are presented.
Influence of emitted electrons transiting between surfaces on plasma-surface interaction
Authors: Campanell Michael , Wang Hongyue
Published: September 2013

Emitted electrons are accelerated back into the plasma by the sheath. If their mean free path is large, they can propagate directly to another surface without suffering collisions. We analyze the effects of “transit” on plasma-surface interaction. When transit occurs, surfaces exchanging electrons are intricately coupled. All surfaces float more negatively than they would if the emission collisionally remixed with the bulk plasma. Asymmetries of the system drive a net “transit current” between the surfaces, which influences their potential difference. The larger the initial energy spread of the emitted electrons, the larger the potential difference.
A novel approach for the characterization of a bilayer of phenyl-c71-butyric-acid-methyl ester and pentacene using ultraviolet photoemission spectroscopy and argon gas cluster ion beam sputtering process
Authors: Yun Dong-Jin , Chung JaeGwan , Jung Changhoon , Chung Yeonji , Kim SeongHeon , Lee Seunghyup , Kim Ki-Hong , Han Hyouksoo , Park Gyeong-Su , Park SungHoon
Published: September 2013

The material arrangement and energy level alignment of an organic bilayer comprising of phenyl-c71-butyric-acid-methyl ester (PCBM-71) and pentacene were studied using ultraviolet photoelectron spectroscopy (UPS) and the argon gas cluster ion beam (GCIB) sputtering process. Although there is a small difference in the full width at half maximum of the carbon C 1s core level peaks and differences in the oxygen O 1s core levels of an X-ray photoemission spectroscopy spectra, these differences are insufficient to clearly distinguish between PCBM-71 and pentacene layers and to classify the interface and bulk regions. On the other hand, the valence band structures in the UPS spectra contain completely distinct configurations for the PCBM-71 and pentacene layers, even when they have similar atomic compositions. According to the valence band structures of the PCBM-71/pentacene/electrodes, the highest unoccupied molecular orbital (HOMO) region of pentacene is at least 0.8 eV closer to the Fermi level than that of PCBM-71 and it does not overlap with any of the chemical states in the valence band structure of PCBM-71. Therefore, by just following the variations in the area of the HOMO region of pentacene, the interface/bulk regions of the PCBM/pentacene layers were distinctly categorized. Besides, the variation of valence band structures as a function of the Ar GCIB sputtering time fully corroborated with the surface morphologies observed in the atomic force microscope images. In summary, we believe that the novel approach, which involves UPS analysis in conjunction with Ar GCIB sputtering, can be one of the best methods to characterize the material distribution and energy level alignments of stacks of organic layers.
Liquid-Sn-driven lateral growth of poly-GeSn on insulator assisted by surface oxide layer
Authors: Kurosawa Masashi , Taoka Noriyuki , Sakashita Mitsuo , Nakatsuka Osamu , Miyao Masanobu , Zaima Shigeaki
Published: September 2013

Effects of surface oxide layers on liquid-Sn-driven GeSn crystallization on insulators at various temperatures (<475 °C) are investigated. An amorphous Ge in neighborhood of patterned-Sn (<3.5 μm) becomes to polycrystalline Ge1−xSnx (x ≈ 0.025 − 0.14) after annealing at 150–475 °C, which is independent of the surface oxide thickness. Interestingly, a 50-μm-length lateral growth of polycrystalline Ge0.99Sn0.01 layers achieved by combination of thickening of the surface-oxide treated by NH4OH and annealing above melting temperature of Sn (231.9 °C). The growth length is 15 times longer than without the treatment. The advanced process promises to achieve group-IV-based optic and electronic devices on flexible substrates and Si platforms.
Sodium chloride protected CdTe quantum dot based solid-state luminophores with high color quality and fluorescence efficiency
Authors: Kalytchuk Sergii , Zhovtiuk Olga , Rogach Andrey L.
Published: September 2013

We report on a series of fluorescent powders based on CdTe colloidal nanocrystals embedded into a protective NaCl matrix, which provide solid-state luminophores with emission colors covering the whole green to red spectral region of visible spectrum and enhanced fluorescence quantum yields comparing to the parent CdTe nanocrystals, unravelled by UV-vis absorption and diffuse reflectance measurements as well as by steady-state and time-resolved photoluminescence spectroscopy. Prototypes of hybrid light-emitting diodes of high color quality utilizing this kind of luminophores as a down-converting layer are demonstrated.
Optical polarization characteristics of m-plane InGaN/GaN quantum well structures and comparison with experiment
Authors: Park Seoung-Hwan , Ahn Doyeol
Published: September 2013

The optical polarization characteristics of the light emission in non-polar m-plane InGaN/GaN quantum well (QW) structures were theoretically investigated using the multiband effective-mass theory. The optical anisotropy of m-plane QW structure is ranging from 0.65 at 440 nm to 0.83 at 560 nm at the sheet carrier density of N2D=15×1012 cm−2 and is found to decrease gradually with increasing carrier density, which is in good agreement with the experimental result. The decrease in the optical anisotropy can be explained by the fact that the y′-polarized matrix element decreases with increasing k‖ while the x′-polarized matrix element gradually increases. Also, the decreasing rate of the QW structure with a smaller In composition is shown to be greater than that of the QW structure with a larger In composition.
Effect of grain size on superelasticity in Fe-Mn-Al-Ni shape memory alloy wire
Authors: Omori T. , Okano M. , Kainuma R.
Published: September 2013

Effects of grain size on superelastic properties in Fe-34Mn-15Al-7.5Ni alloy wires with a ⟨110⟩ fiber-texture were investigated by cyclic tensile tests. It was confirmed that the critical stress for induced martensitic transformation and the superelastic strain are functions of relative grain size d/D (d: mean grain diameter, D: wire diameter), and that the critical stress is proportional to (1–d/D)2 as well as in Cu-based shape memory alloys. A large superelastic strain of about 5% was obtained in the specimen with a large relative grain size over d/D = 1.
Great enhancement of near band-edge emission of ZnSe two-dimensional complex nanostructures fabricated by the interference of three femtosecond laser beams
Authors: Pan Jia , Jia Tianqing , Huo Yanyan , Jia Xin , Feng Donghai , Zhang Shian , Sun Zhenrong , Xu Zhizhan
Published: September 2013

By using the method of the interference of three 800 nm femtosecond laser beams, we fabricated complex 2-dimensional (2D) micro/nanostructures on ZnSe crystal. Compared with the plane surface of ZnSe crystal, 2D nanostructures exhibit a great enhancement of near band-edge (NBE) emission and a compression of second harmonic generation (SHG) under excitation of infrared (IR) femtosecond laser with central wavelengths ranging from 1200 to 1600 nm. We studied the photoluminescence properties of 2D nanostructures and the mechanism of the enhancement of NBE emission. Our results indicated that the enhancement of NBE emission is caused by a combination of several processes including the increase in optical absorption, and the reabsorption of SHG by the nanostructures.
Effects of crystal quality and preferred orientation on the irreversible growth of compact TATB cylindrical explosives
Authors: Zhang Haobin , Xu Jingjiang , Liu Yu , Huang Hui , Sun Jie
Published: September 2013

Three kinds of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) cylinders compacted with TATB raw materials, recrystallized near-spherical and platy TATB crystals are compared to investigate the effects of crystal quality and preferred orientation on their irreversible growth. The results show that the higher the crystal quality, the lower the irreversible volume growth. The compacted cylinders of raw material TATB, with the poorest crystal quality, possess more irreversible growth than those with recrystallized high quality TATB crystals. Irreversible growth of TATB cylinders are also affected by crystal preferred orientation. With the same crystal quality, crystal preferred orientation leads to anisotropic irreversible dimension growth, but has no effect on the volume expansion of TATB cylinders. By changing the crystal quality and preferred orientation, the deformation problem of TATB-based PBX explosives may be restricted.
Exchange biased FeNi/FeMn bilayers with coercivity and switching field enhanced by FeMn surface oxidation
Authors: Svalov A. V. , Savin P. A. , Lepalovskij V. N. , Larrañaga A. , Vas'kovskiy V. O. , Arribas A. Garcia , Kurlyandskaya G. V.
Published: September 2013

FeNi/FeMn bilayers were grown in a magnetic field and subjected to heat treatments at temperatures of 50 to 350 °C in vacuum or in a gas mixture containing oxygen. In the as-deposited state, the hysteresis loop of 30 nm FeNi layer was shifted. Low temperature annealing leads to a decrease of the exchange bias field. Heat treatments at higher temperatures in gas mixture result in partial oxidation of 20 nm thick FeMn layer leading to a nonlinear dependence of coercivity and a switching field of FeNi layer on annealing temperature. The maximum of coercivity and switching field were observed after annealing at 300 °C.
Effect of added dietary nitrate and elemental sulfur on wool growth and methane emission of Merino lambs
Authors: Li L. , Silveira C. I. , Nolan J. V. , Godwin I. R. , Leng R. A. , Hegarty R. S.
Published: September 2013

The effects of dietary nitrate (NO3) and elemental sulfur (S) on nutrient utilisation, productivity, and methane emission of Merino lambs were investigated. Forty-four lambs were randomly allocated to four groups (n = 11) fed isonitrogenous and isoenergetic diets. The basal feed was supplemented with 1% urea + 0.18% S (T1), 1.88% NO3 + 0% S (T2), 1.88% NO3 + 0.18% S (T3), or 1.88% NO3 + 0.40% S (T4). Retention of S was improved by increasing the content of elemental S in the NO3-containing diet (P < 0.001), yet the N retention (g/day) by the animal, and the N and S content of wool (%), were not altered by S supplementation (P > 0.05). Dry matter intake, liveweight gain, and feed conversion ratio did not differ (P > 0.05) between treatments. Replacing urea with NO3 improved the rate of clean wool growth by 37% (P < 0.001, T1 vs T3). Clean wool growth increased by 26% (P < 0.001) when the S content of the NO3-containing diet was increased from 0 to 0.18% (T2 vs T3). Methane production (g/day) and methane yield (g/kg DM intake) were reduced (P < 0.05) by 24% when urea was replaced by NO3 (T1 vs T3). The addition of 0.4% S to a diet containing 1.88% NO3 also reduced methane production (P = 0.021) and methane yield (P = 0.028). In conclusion, the addition of 1.88% NO3 and 0.18% elemental S to a total mixed diet increased clean wool production and reduced methane production. However, there was no evidence of inter-relationships between NO3 and S.
Negative short-term salt effects on the soybean–Bradyrhizobium japonicum interaction and partial reversion by calcium addition
Authors: Muñoz Nacira , Rodriguez Marianela , Robert German , Lascano Ramiro
Published: September 2013

The short-term (2 h) effects of salt stress (50 and 150 mM NaCl) on early events of soybean– Bradyrhizobium japonicum (rhizobia) interaction were analysed, determining the following parameters in root hair with or without calcium addition: deformation, apoplastic superoxide radical production (O2⚫–), root hair death and sodium/potassium ion content. We also analysed whether this short-term salt stress influenced later formation of crown and noncrown nodules, determining the number and weight of nodules. The negative effect of salt stress on these characters was attenuated by the addition of 5 mM CaCl2. We also analysed the expression of pathogenesis-related proteins (PRP) genes PR-1, PR-2, PR-3, and four isoforms of PR-5. The expression of PR-2 increased under saline conditions and decreased in osmotic treatment and saline treatment supplemented with calcium in the presence of the symbiont. The changes in PR-2 expression levels, together with the death of root hairs provide a possible mechanism for the inhibition of infection by the symbiont under salinity, and suggests a possible overlap with responses to plant pathogens.
Chiral heliconical ground state of nanoscale pitch in a nematic liquid crystal of achiral molecular dimers
Authors: Chen Dong , Porada Jan H. , Hooper Justin B. , Klittnick Arthur , Shen Yongqiang , Tuchband Michael R. , Korblova Eva , Bedrov Dmitry , Walba David M. , Glaser Matthew A. , Maclennan Joseph E. , Clark Noel A.
Published: September 2013

Significance

The appearance of new nematic liquid crystal (LC) equilibrium symmetry (ground state) is a rare and typically important event. The first and second nematics were the helical phase and blue phase of chiral molecules, both found in 1886 in cholesteryl benzoate by Reinitzer, discoveries that marked the birth of LC science. The third nematic, the achiral uniaxial phase, also found in the 19th century, ultimately formed the basis of LC display technology and the portable computing revolution of the 20th century. Despite this achievement, the 20th can claim only the fourth nematic, the lyotropic biaxial phases found by Saupe. Now, early in the 21st, the heliconical structure of the fifth nematic is observed, an exotic chiral helix from achiral molecules.