bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved algorithm for processing grating-based phase contrast interferometry image sets
Authors: Marathe Shashidhara , Assoufid Lahsen , Xiao Xianghui , Ham Kyungmin , Johnson Warren W. , Butler Leslie G.
Published: January 2014

Grating-based X-ray and neutron interferometry tomography using phase-stepping methods generates large data sets. An improved algorithm is presented for solving for the parameters to calculate transmissions, differential phase contrast, and dark-field images. The method takes advantage of the vectorization inherent in high-level languages such as Mathematica and MATLAB and can solve a 16 × 1k × 1k data set in less than a second. In addition, the algorithm can function with partial data sets. This is demonstrated with processing of a 16-step grating data set with partial use of the original data chosen without any restriction. Also, we have calculated the reduced chi-square for the fit and notice the effect of grating support structural elements upon the differential phase contrast image and have explored expanded basis set representations to mitigate the impact.
Dielectric tunability analysis of pyrochlore Bi1.5Zn1.0Nb1.5O7 using epitaxial films on pyrochlore Bi2Ru2O7 conductive layers
Authors: Nakajima Mitsumasa , Ikariyama Rikyu , Sankara Rama Krishnan P. S. , Yamada Tomoaki , Funakubo Hiroshi
Published: January 2014

To investigate the origin of the dielectric tunability, epitaxial Bi1.5Zn1.0Nb1.5O7 (BZN) films are grown on a pyrochlore Bi2Ru2O7 conductive layer by metal-organic chemical vapor deposition. The dielectric tunability is 41% at 2.5 MV/cm in the temperature range of 100–300 K, but is significantly suppressed below ∼100 K, suggesting that the dielectric tunability of the BZN film is due to random dipole contributions. However, a non-negligible dielectric tunability remains even at 4 K, implying that additional factors, such as phonons, contribute to the tunability.
Comparison of magnetic probe calibration at nano and millitesla magnitudes
Authors: Pahl Ryan A. , Rovey Joshua L. , Pommerenke David J.
Published: January 2014

Magnetic field probes are invaluable diagnostics for pulsed inductive plasma devices where field magnitudes on the order of tenths of tesla or larger are common. Typical methods of providing a broadband calibration of \documentclass[12pt]{minimal}\begin{document}$\dot{\rm{B}}$\end{document}Ḃ probes involve either a Helmholtz coil driven by a function generator or a network analyzer. Both calibration methods typically produce field magnitudes of tens of microtesla or less, at least three and as many as six orders of magnitude lower than their intended use. This calibration factor is then assumed constant regardless of magnetic field magnitude and the effects of experimental setup are ignored. This work quantifies the variation in calibration factor observed when calibrating magnetic field probes in low field magnitudes. Calibration of two \documentclass[12pt]{minimal}\begin{document}$\dot{\rm{B}}$\end{document}Ḃ probe designs as functions of frequency and field magnitude are presented. The first \documentclass[12pt]{minimal}\begin{document}$\dot{\rm{B}}$\end{document}Ḃ probe design is the most commonly used design and is constructed from two hand-wound inductors in a differential configuration. The second probe uses surface mounted inductors in a differential configuration with balanced shielding to further reduce common mode noise. Calibration factors are determined experimentally using an 80.4 mm radius Helmholtz coil in two separate configurations over a frequency range of 100–1000 kHz. A conventional low magnitude calibration using a vector network analyzer produced a field magnitude of 158 nT and yielded calibration factors of 15 663 ± 1.7% and 4920 ± 0.6% \documentclass[12pt]{minimal}\begin{document}$\frac{\rm{T}}{\rm{V}\, \rm{s}}$\end{document}TVs at 457 kHz for the surface mounted and hand-wound probes, respectively. A relevant magnitude calibration using a pulsed-power setup with field magnitudes of 8.7–354 mT yielded calibration factors of 14 615 ± 0.3% and 4507 ± 0.4% \documentclass[12pt]{minimal}\begin{document}$\frac{\rm{T}}{\rm{V}\, \rm{s}}$\end{document}TVs at 457 kHz for the surface mounted inductor and hand-wound probe, respectively. Low-magnitude calibration resulted in a larger calibration factor, with an average difference of 9.7% for the surface mounted probe and 12.0% for the hand-wound probe. The maximum difference between relevant and low magnitude tests was 21.5%.
Determination of carrier concentration dependent electron effective mass and scattering time of n-ZnO thin film by terahertz time domain spectroscopy
Authors: Tang J. , Deng L. Y. , Tay C. B. , Zhang X. H. , Chai J. W. , Qin H. , Liu H. W. , Venkatesan T. , Chua S. J.
Published: January 2014

We demonstrated a novel and widely accessible method for determining the electron effective mass and scattering time of ZnO films with different carrier concentrations by combining terahertz time-domain spectroscopy with Hall measurement. The terahertz time domain spectroscopy (THz-TDS) transmission spectra (0.1–2THz) were well described by Drude model. It is found that electron effective mass varied from 0.23m0 to 0.26m0 as the electron concentration changes from 5.9 × 1017 cm−3 to 4.0 × 1019 cm−3. The carrier concentration dependent characteristic is ascribed to the non-parabolicity of conduction band. Free carrier localization mechanism explained the discrepancy in mobilities obtained from THz-TDS and Hall measurements.
Tandem array of nanoelectronic readers embedded coplanar to a fluidic nanochannel for correlated single biopolymer analysis
Authors: Lesser-Rojas Leonardo , Sriram K. K. , Liao Kuo-Tang , Lai Shui-Chin , Kuo Pai-Chia , Chu Ming-Lee , Chou Chia-Fu
Published: January 2014

We have developed a two-step electron-beam lithography process to fabricate a tandem array of three pairs of tip-like gold nanoelectronic detectors with electrode gap size as small as 9 nm, embedded in a coplanar fashion to 60 nm deep, 100 nm wide, and up to 150 μm long nanochannels coupled to a world-micro-nanofluidic interface for easy sample introduction. Experimental tests with a sealed device using DNA-protein complexes demonstrate the coplanarity of the nanoelectrodes to the nanochannel surface. Further, this device could improve transverse current detection by correlated time-of-flight measurements of translocating samples, and serve as an autocalibrated velocimeter and nanoscale tandem Coulter counters for single molecule analysis of heterogeneous samples.
Resonance electron attachment to plant hormones and its likely connection with biochemical processes
Authors: Pshenichnyuk Stanislav A. , Modelli Alberto
Published: January 2014

Gas-phase formation of temporary negative ion states via resonance attachment of low-energy (0–6 eV) electrons into vacant molecular orbitals of salicylic acid (I) and its derivatives 3-hydroxy- (II) and 4-hydroxybenzoic acid (III), 5-cloro salicylic acid (IV) and methyl salicylate (V) was investigated for the first time by electron transmission spectroscopy. The description of their empty-level structures was supported by density functional theory and Hartree-Fock calculations, using empirically calibrated linear equations to scale the calculated virtual orbital energies. Dissociative electron attachment spectroscopy (DEAS) was used to measure the fragment anion yields generated through dissociative decay channels of the parent molecular anions of compounds I–V, detected with a mass filter as a function of the incident electron energy in the 0–14 eV energy range. The most intense negative fragment produced by DEA to isomers I–III is the dehydrogenated molecular anion [M–H]−, mainly formed at incident electron energies around 1 eV. The vertical and adiabatic electron affinities were evaluated at the B3LYP/6-31+G(d) level as the anion/neutral total energy difference. The same theoretical method was also used for evaluation of the thermodynamic energy thresholds for production of the negative fragments observed in the DEA spectra. The gas-phase DEAS data can provide support for biochemical reaction mechanisms in vivo.
High-resolution measurements of the spatial and temporal evolution of megagauss magnetic fields created in intense short-pulse laser-plasma interactions
Authors: Chatterjee Gourab , Singh Prashant Kumar , Adak Amitava , Lad Amit D. , Kumar G. Ravindra
Published: January 2014

A pump-probe polarimetric technique is demonstrated, which provides a complete, temporally and spatially resolved mapping of the megagauss magnetic fields generated in intense short-pulse laser-plasma interactions. A normally incident time-delayed probe pulse reflected from its critical surface undergoes a change in its ellipticity according to the magneto-optic Cotton-Mouton effect due to the azimuthal nature of the ambient self-generated megagauss magnetic fields. The temporal resolution of the magnetic field mapping is typically of the order of the pulsewidth, limited by the laser intensity contrast, whereas a spatial resolution of a few μm is achieved by this optical technique. High-harmonics of the probe can be employed to penetrate deeper into the plasma to even near-solid densities. The spatial and temporal evolution of the megagauss magnetic fields at the target front as well as at the target rear are presented. The μm-scale resolution of the magnetic field mapping provides valuable information on the filamentary instabilities at the target front, whereas probing the target rear mirrors the highly complex fast electron transport in intense laser-plasma interactions.
Nonlinear response theory in chemical kinetics
Authors: Kryvohuz Maksym , Mukamel Shaul
Published: January 2014

A theory of nonlinear response of chemical kinetics, in which multiple perturbations are used to probe the time evolution of nonlinear chemical systems, is developed. Expressions for nonlinear chemical response functions and susceptibilities, which can serve as multidimensional measures of the kinetic pathways and rates, are derived. A new class of multidimensional measures that combine multiple perturbations and measurements is also introduced. Nonlinear fluctuation-dissipation relations for steady-state chemical systems, which replace operations of concentration measurement and perturbations, are proposed. Several applications to the analysis of complex reaction mechanisms are provided.
G-systems and deformation of G-actions on ${\mathbb {R}}^{d}$Rd
Authors: Dherin Benoit , Mencattini Igor
Published: January 2014

Given a (smooth) action φ of a Lie group G on \documentclass[12pt]{minimal}\begin{document}${\mathbb {R}}^d$\end{document}Rd we construct a differential graded algebra whose Maurer–Cartan elements are in one-to-one correspondence with some class of deformations of the (induced) G-action on \documentclass[12pt]{minimal}\begin{document}$C^{\infty }({\mathbb {R}}^d)[[\hbar ]]$\end{document}C∞(Rd)[[ℏ]]. In the final part of this note we discuss the cohomological obstructions to the existence and to the uniqueness (in a sense to be clarified) of such deformations.
Preliminary results from direct-drive cryogenic target implosion experiments on SGIII prototype laser facility
Authors: Yu-dong Pu , Tian-Xuan Huang , Ping Li , Hai-le Lei , Jun Li , Shao-En Jiang , Huang Li , Zhi-Wen Yang , Jian Teng , Bo Wu , Kai Wang , Wei Lin , Ming Su , Xia-Yu Zhan , Li Chen , Xiao-Shi Peng , Tang-Qi  , Zi-Feng Song , Jia-Bin Chen , Ming Chen , Rui-Zhen Yu , Jia-Hua Zheng , Long-Fei Jing , Bo-Lun Chen , Wei Jiang , Bo Yu , Ji Yan , Yong-Kun Ding
Published: January 2014

Since ignition target design with layered deuterium and triterium ice had been proposed several decades ago, much effort was devoted to fabricate and implode cryogenic targets. Until recently, direct-drive cryogenic target implosion experiment was carried out on SGIII prototype laser facility. The target consisted of a plastic capsule supported by fill tube. Cryogenic helium gas was used to cool the capsule to a few degrees below the deuterium triple point. The resulting deuterium ice layer was characterized by optical shadowgraph and smoothed by applied temperature gradient. Eight laser beams with total energy of 7 kJ were used to directly drive the implosion. On the path of laser light to the capsule, there were 500 nm sealing film and helium gas of mm length. X-ray pinhole images were analyzed to confirm that the sealing film, and helium gas had little effect on aiming accuracy but caused some loss of laser energy especially when condensation on the sealing film was observed.
Oscillations in two-dimensional photon-echo signals of excitonic and vibronic systems: Stick-spectrum analysis and its computational verification
Authors: Egorova Dassia
Published: January 2014

Stick-spectrum expressions for electronic two-dimensional (2D) photon-echo (PE) signal of a generic multi-level system are presented and employed to interrelate oscillations in individual peaks of 2D PE signal and the underlying properties (eigenstates and coherent dynamics) of excitonic or vibronic systems. When focusing on the identification of the origin of oscillations in the rephasing part of 2D PE it is found, in particular, that multiple frequencies in the evolution of the individual peaks do not necessarily directly reflect the underlying system dynamics. They may originate from the excited-state absorption contribution to the signal, or arise due to multi-level vibrational structure of the electronic ground state, and represent a superposition of system frequencies, while the latter may evolve independently. The analytical stick-spectrum predictions are verified and illustrated by numerical calculations of 2D PE signals of an excitonic trimer and of a displaced harmonic oscillator with unequal vibrational frequencies in the two electronic states. The excitonic trimer is the smallest excitonic oligomer where excited-state absorption may represent a superposition of excited-state coherences and significantly influence the phase of the observed oscillations. The displaced oscillator is used to distinguish between the frequencies of the ground-state and of the excited-state manifolds, and to demonstrate how the location of a cross peak in 2D pattern of the PE signal “predetermines” its oscillatory behavior. Although the considered models are kept as simple as possible for clarity, the stick-spectrum analysis provides a solid general basis for interpretation of oscillatory signatures in electronic 2D PE signals of much more complex systems with multi-level character of the electronic states.
Results for aliovalent doping of CeBr3 with Ca2+
Authors: Guss Paul , Foster Michael E. , Wong Bryan M. , Patrick Doty F. , Shah Kanai , Squillante Michael R. , Shirwadkar Urmila , Hawrami Rastgo , Tower Joshua , Yuan Ding
Published: January 2014

Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide, their commercial availability and application are limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. This investigation employed aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was used as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown, i.e., 1.9% of the CeBr3 molecules were replaced by CaBr2 molecules, to match our target replacement of 1 out of 54 cerium atoms be replaced by a calcium atom. Precisely the mixture was composed of 2.26 g of CaBr2 added to 222.14 g of CeBr3. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were studied using the density functional theory within the generalized gradient approximation. Calculated lattice parameters are in agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.
NO dissociation through ns, np, and nf Rydberg states: Angular distributions
Authors: Chen J. , Strangfeld B. R. , Houston P. L.
Published: January 2014

Velocity-mapped imaging and theoretical calculations have been used to study the angular distribution of the products of NO predissociation following its excitation to the 11s, 10p, 11p, and 9f Rydberg levels based on the NO+ (X 2Σ+) core. The Rydberg states were reached from the NO (A 2Σ+, v = 0, N = 2, J = 1.5) level prepared with strong alignment by excitation with linear polarization from NO (X 2Π, v = 0, N = 1, J = 0.5). Ion dip spectra of the Rydberg states were recorded along with velocity-mapped images at the major peaks. The results are compared to calculations based on a previous theoretical approach modified to include transitions to states of Hund's case (d) coupling. The reasonable agreement shows the predictive value of the theory. The theory has also been used to reassess and explain previous results and to understand variations in the rate of photodissociation with components of the 10p and 11p Rydberg states.
Monocarbon cationic cluster yields from N2/CH4 mixtures embedded in He nanodroplets and their calculated binding energies
Authors: Tolbatov Iogann , Bartl Peter , Yurkovich James , Scheier Paul , Chipman Daniel M. , Denifl Stephan , Ptasinska Sylwia
Published: January 2014

The formation of monocarbon cluster ions has been investigated by electron ionization mass spectrometry of cold helium nanodroplets doped with nitrogen/methane mixtures. Ion yields for two groups of clusters, CHmN2+ or CHmN4+, were determined for mixtures with different molecular ratios of CH4. The possible geometrical structures of these clusters were analyzed using electronic structure computations. Little correlation between the ion yields and the associated binding energies has been observed indicating that in most cases kinetic control is more important than thermodynamic control for forming the clusters.
Effects of reactant rotational excitation on reactivity: Perspectives from the sudden limit
Authors: Jiang Bin , Li Jun , Guo Hua
Published: January 2014

Excitation of reactant rotational degrees of freedom is known to influence reactivity in bimolecular reactions. In this work, this effect is examined for several prototypical activated atom-diatom and atom-triatom reactions through exact quantum scattering calculations on accurate ab initio potential energy surfaces. To rationalize these mode-specific effects, the recently proposed sudden vector overlap model is extended to include rotational motions of reactants. Specifically, the enhancement of reactivity is attributed to their coupling with the reaction coordinate at the transition state, as quantified by the alignment between the corresponding normal mode vectors. In addition, a Franck-Condon model is introduced to predict the effect of reactant rotational excitation for reactions in which the reactant rotations are decoupled from the reaction coordinate.
Moore–Penrose generalized inverse of the gradient tensor in Euler's equation for locating a magnetic dipole
Authors: Nara T. , Ito W.
Published: January 2014

Euler's equation provides us with a system of linear equations for localizing a magnetic dipole from measurements of the magnetic field and its gradients. However, so far, the condition for the coefficient matrix of the linear equations to be singular has not been shown. In this paper, we show that the matrix is singular if and only if the dipole moment is perpendicular to the dipole position vector, where the observation point is set at the origin. Moreover, we show that, even in this case, the true position can be uniquely reconstructed by using the Moore–Penrose generalized inverse of the gradient tensor.
Matrix elements for type 1 unitary irreducible representations of the Lie superalgebra gl(m|n)
Authors: Gould Mark D. , Isaac Phillip S. , Werry Jason L.
Published: January 2014

Using our recent results on eigenvalues of invariants associated to the Lie superalgebra gl(m|n), we use characteristic identities to derive explicit matrix element formulae for all gl(m|n) generators, particularly non-elementary generators, on finite dimensional type 1 unitary irreducible representations. We compare our results with existing works that deal with only subsets of the class of type 1 unitary representations, all of which only present explicit matrix elements for elementary generators. Our work therefore provides an important extension to existing methods, and thus highlights the strength of our techniques which exploit the characteristic identities.
Killing tensors, warped products and the orthogonal separation of the Hamilton-Jacobi equation
Authors: Rajaratnam Krishan , McLenaghan Raymond G.
Published: January 2014

We study Killing tensors in the context of warped products and apply the results to the problem of orthogonal separation of the Hamilton-Jacobi equation. This work is motivated primarily by the case of spaces of constant curvature where warped products are abundant. We first characterize Killing tensors which have a natural algebraic decomposition in warped products. We then apply this result to show how one can obtain the Killing-Stäckel space (KS-space) for separable coordinate systems decomposable in warped products. This result in combination with Benenti's theory for constructing the KS-space of certain special separable coordinates can be used to obtain the KS-space for all orthogonal separable coordinates found by Kalnins and Miller in Riemannian spaces of constant curvature. Next we characterize when a natural Hamiltonian is separable in coordinates decomposable in a warped product by showing that the conditions originally given by Benenti can be reduced. Finally, we use this characterization and concircular tensors (a special type of torsionless conformal Killing tensor) to develop a general algorithm to determine when a natural Hamiltonian is separable in a special class of separable coordinates which include all orthogonal separable coordinates in spaces of constant curvature.
Signature of quantum entanglement in NH4CuPO4·H2O
Authors: Chakraborty Tanmoy , Singh Harkirat , Mitra Chiranjib
Published: January 2014

Entangled solid state systems have gained a great deal of attention due to their fruitful applications in modern quantum technologies. Herein, detection of entanglement content from experimental magnetic susceptibility and specific heat data is reported for NH4CuPO4·H2O in its solid state crystalline form. NH4CuPO4·H2O is a prototype of Heisenberg spin 1/2 dimer system. Temperature dependent magnetic susceptibility and specific data are fitted to an isolated dimer model and the exchange coupling constant is determined. Field dependent magnetization isotherms taken at different temperatures are plotted in a three dimensional plot. Subsequently, entanglement is detected both from susceptibility and specific heat through two different entanglement measures; entanglement witness and entanglement of formation. The temperature evolution of entanglement is studied and the critical temperature is determined up to which entanglement exists. Temperature dependent nature of entanglement extracted from susceptibility and specific heat shows good consistency with each other. Moreover, the field dependent entanglement is also investigated.
Short-term load forecasting in electrical power systems via trajectory tracking and error correcting approach
Authors: Song Yongduan , Shen Zhixi , Dai Donglin , Qian Yanan , Wang Yujuan
Published: January 2014

Rapid and accurate load forecasting is essential for renewable yet highly stochastic power (such as wind and solar power) to be massively utilized in practice. While there are many load forecasting methods reported in the literature, most of which, however, do not literally guarantee the convergence of forecasting error. This paper proposes a new error correcting approach for load forecasting in power systems by using trajectory tracking stability theory. In principle, the proposed method is not an autonomous but heuristic correcting approach to assess and improve the results of other existing models. This method is able to ensure the convergence of forecasting error in theory and is independent of system model, making it more feasible and cost-effective for forecasting performance improvement. Simulation experiments confirm the effectiveness of the proposed method for multiple existing models and forecasting horizons.
Optically detected, single nanoparticle mass spectrometer with pre-filtered electrospray nanoparticle source
Authors: Howder Collin R. , Bell David M. , Anderson Scott L.
Published: January 2014

An instrument designed for non-destructive mass analysis of single trapped nanoparticles is described. The heart of the instrument is a 3D quadrupole (Paul) trap constructed to give optical access to the trap center along ten directions, allowing passage of lasers for particle heating and detection, particle injection, collection of scattered or fluorescent photons for particle detection and mass analysis, and collection of particles on TEM grids for analysis, as needed. Nanoparticles are injected using an electrospray ionization (ESI) source, and conditions are described for spraying and trapping polymer particles, bare metal particles, and ligand stabilized particles with masses ranging from 200 kDa to >3 GDa. Conditions appropriate to ESI and injection of different types of particles are described. The instrument is equipped with two ion guides separating the ESI source and nanoparticle trap. The first ion guide is mostly to allow desolvation and differential pumping before the particles enter the trap section of the instrument. The second is a linear quadrupole guide, which can be operated in mass selective or mass band-pass modes to limit transmission to species with mass-to-charge ratios in the range of interest. With a little experience, the design allows injection of single particles into the trap upon demand.
Interactions of vortices with a flexible beam with applications in fluidic energy harvesting
Authors: Goushcha O. , Elvin N. , Andreopoulos Y.
Published: January 2014

A cantilever piezoelectric beam immersed in a flow and subjected to naturally occurring vortices such as those formed in the wake of bluff bodies can be used to generate electrical energy harvested in fluid flows. In this paper, we present the pressure distribution and deflection of a piezoelectric beam subjected to controlled vortices. A custom designed experimental facility is set up to study the interaction of individual and multiple vortices with the beam. Vortex tori are generated by an audio speaker and travel at controlled rates over the beam. Particle image velocimetry is used to measure the 2-D flow field induced by each vortex and estimate the effect of pressure force on the beam deflection.
Two-component coupled KdV equations and its connection with the generalized Harry Dym equations
Authors: Popowicz Ziemowit
Published: January 2014

It is shown that three different Lax operators in the Dym hierarchy produce three generalized coupled Harry Dym equations. These equations transform, via the reciprocal link, to the coupled two-component Korteweg de Vries (KdV) system. The first equation gives us known integrable two-component KdV system, while the second reduces to the known symmetrical two-component KdV equation. The last one reduces to the Drienfeld-Sokolov equation. This approach gives us new Lax representation for these equations.
Semiclassical wave-packets emerging from interaction with an environment
Authors: Recchia Carla , Teta Alessandro
Published: January 2014

We study the quantum evolution in dimension three of a system composed by a test particle interacting with an environment made of N harmonic oscillators. At time zero the test particle is described by a spherical wave, i.e., a highly correlated continuous superposition of states with well localized position and momentum, and the oscillators are in the ground state. Furthermore, we assume that the positions of the oscillators are not collinear with the center of the spherical wave. Under suitable assumptions on the physical parameters characterizing the model, we give an asymptotic expression of the solution of the Schrödinger equation of the system with an explicit control of the error. The result shows that the approximate expression of the wave function is the sum of two terms, orthogonal in \documentclass[12pt]{minimal}\begin{document}$L^2(\mathbb {R}^{3(N+1)})$\end{document}L2(R3(N+1)) and describing rather different situations. In the first one, all the oscillators remain in their ground state and the test particle is described by the free evolution of a slightly deformed spherical wave. The second one consists of a sum of N terms where in each term there is only one excited oscillator and the test particle is correspondingly described by the free evolution of a wave packet, well concentrated in position and momentum. Moreover, the wave packet emerges from the excited oscillator with an average momentum parallel to the line joining the oscillator with the center of the initial spherical wave. Such wave packet represents a semiclassical state for the test particle, propagating along the corresponding classical trajectory. The main result of our analysis is to show how such a semiclassical state can be produced, starting from the original spherical wave, as a result of the interaction with the environment.
Bound states in a hyperbolic asymmetric double-well
Authors: Hartmann R. R.
Published: January 2014

We report a new class of hyperbolic asymmetric double-well whose bound state wavefunctions can be expressed in terms of confluent Heun functions. An analytic procedure is used to obtain the energy eigenvalues and the criterion for the potential to support bound states is discussed.
Study of CeI3 evaporation in the presence of group 13 metal-iodides
Authors: Curry J. J. , Estupiñán E. G. , Lapatovich W. P. , Henins A. , Shastri S. D. , Hardis J. E. , Gibbs J. M.
Published: January 2014

The influences of GaI3, InI, and TlI on the evaporation characteristics of CeI3 have been studied over the temperature range 900 K to 1400 K using x-ray induced fluorescence. The total vapor densities, summed over all atomic and molecular species, of Ce, I, In, and Tl were obtained. Measurements of Ce were limited to temperatures above 1033 K, the melting temperature of CeI3. This is the highest temperature range for which measurements of the vapor pressure of CeI3 have been made. The vapor pressure of the CeI3 monomer above the pure CeI3 salt for temperatures exceeding its melting point can be approximated by log10p/Pa=11.24(±0.03)−10,690(±40) (T/K)−1 where the numbers in parentheses are standard uncertainties. InI and TlI were shown to modestly enhance the presence of Ce in the vapor phase, up to a factor of 5. GaI3 produced no enhancement in this temperature range. Numerical simulations of the thermochemical equilibrium suggest the importance of both liquid-phase and vapor-phase complexes. Significant improvement to the method of absolute calibration is discussed.
Compositional dependence of magnetic and high frequency properties of nanogranular FeCo-TiO2 films
Authors: Wang Yicheng , Zhang Huaiwu , Wang Luo , Bai Feiming
Published: January 2014

A series of soft magnetic nanogranular FeCo-TiO2 films with different compositions of FeCo were fabricated on Si substrates by co-sputtering FeCo and TiO2, and the magnetic and high frequency properties were studied in details. X-ray diffraction analysis confirmed that the films were nanocrystalline/amorphous composites. A high saturation magnetization of 14 kGs, a low coercivity of 5.3 Oe, a FMR frequency of 3.2 GHz, and a high resistivity of 1068 μΩ cm were obtained when the volume fraction of FeCo was 0.68. The excellence electromagnetic properties make the films an excellent candidate for microwave applications.
On the photoelectron velocity-map imaging of lutetium monoxide anion LuO−
Authors: Liu Zhiling , Xie Hua , Li Quanjiang , Qin Zhengbo , Cong Ran , Wu Xia , Tang Zichao , Fan Hongjun
Published: January 2014

We report a combined photoelectron velocity-map imaging spectroscopy and density functional theory investigation on lutetium monoxide anion. Transition between the X 1Σ+ anion electronic ground state and the neutral X 2Σ+ electronic ground state is observed. Vibrationally resolved spectra were obtained at four different photon energies, providing a wealth of spectroscopic information for the electronic ground states of the anionic lutetium monoxide and corresponding neutral species. Franck-Condon simulations of the ground-state transition are performed to assign vibrational structure in the spectra and to assist in identifying the observed spectral bands. The electronic ground state of LuO− is found to have a vibrational frequency of 743 ± 10 cm−1 and an equilibrium bond length of 1.841 Å. The electron affinity of LuO is measured to be 1.624 ± 0.002 eV. The fundamental frequency of ground-state LuO is estimated to be 839 ± 10 cm−1.
Surface tension of spherical drops from surface of tension
Authors: Homman A.-A. , Bourasseau E. , Stoltz G. , Malfreyt P. , Strafella L. , Ghoufi A.
Published: January 2014

The determination of surface tension of curved interfaces is a topic that raised many controversies during the last century. Explicit liquid-vapor interface modelling (ELVI) was unable up to now to reproduce interfacial behaviors in drops due to ambiguities in the mechanical definition of the surface tension. In this work, we propose a thermodynamic approach based on the location of surface of tension and its use in the Laplace equation to extract the surface tension of spherical interfaces from ELVI modelling.
Twisted ferroelectric liquid crystals dynamic behaviour modification under electric field: A Mueller matrix polarimetry approach using birefringence
Authors: Babilotte P. , Nunes Henrique Silva V. , Sathaye K. , Dubreuil M. , Rivet S. , Dupont L. , de Bougrenet de la Tocnaye J. L. , Le Jeune B.
Published: January 2014

A low frequency and high amplitude rectangular voltage V has been applied during different increased duration to Twisted Surface Stabilized Ferroelectric Liquid crystal (TwFLC) samples in which the alignment layers of the two substrates were rubbed along two different directions between 0° and 90°. The optical bistability properties have been evaluated using the specific Mueller Matrix formalism that allows a simultaneous access, through a single-shot measurement, to different polarimetric coefficients. In this new approach, the ellipticity ϵR and the azimuthal αR polarimetric parameters, extracted from the birefringence Mueller Matrix MR will be considered in priority. Several significant parameters, such as the horizontal offset ΔV, the degree of asymmetry DA, the characteristic area S of the hysteresis loop, are used to characterize the degradation observed into the hysteretic behaviour of the samples, for different values of ψ, at different duration T of exposure to V, before reaching the so-called stripes regime, giving a new experimental point of view concerning the evolution of the dynamic properties of the samples studied. The αR(V) and the ϵR(V) hysteresis loops are specifically examined. Static mapping related to ϵR(T) is given too. Among the different possible physical origins of the observed degradation, the in-plane anchoring energy contribution will be particularly examined, and a theoretical model is proposed that also gives access to different physical parameters, through a new approach.
Phosphorus doping of Si nanocrystals embedded in silicon oxynitride determined by atom probe tomography
Authors: Gnaser Hubert , Gutsch Sebastian , Wahl Michael , Schiller Rüdiger , Kopnarski Michael , Hiller Daniel , Zacharias Margit
Published: January 2014

Silicon nanocrystals (SiNCs) embedded in a silicon oxide matrix were studied by 3D atom probe tomography (APT). The distribution of the SiNC diameter was found to have a mean value of 3.7 ± 0.8 nm. The elemental composition of these particles was determined by employing two different approaches: (i) The proximity histogram method and (ii) a cluster identification algorithm based on maximum-atom separations. Both approaches give very similar values in terms of the amount of P, O, and Si within the SiNCs: the mean atomic concentrations are cP = 0.77% ± 0.4%, cO = 12.3% ± 2.1%, and cSi = 85.3% ± 2.1%. A detailed cluster analysis implies that, on average, a 4.5-nm SiNC would contain around 30 P atoms, whereas a 2.0-nm SiNC would contain only around 3 P atoms. Radial concentration profiles obtained for these SiNCs indicate that the P content is inhomogeneous and possibly enhanced at the boundary as compared to the interior of the NCs. About 20% of the P atoms are found to be incorporated into the SiNCs, whereas roughly 30% are trapped within the interfacial layer (with a thickness of ∼ 0.8 nm); the remainder resides in the surrounding matrix. Cluster-size dependent P concentrations support the view of self-purification in the Si nanostructures.
A complete model of wind turbines for lightning transient analysis
Authors: Zhang Xiaoqing , Zhang Yongzheng , Liu Chenghua
Published: January 2014

A transient analysis is performed in this paper for the wind turbines (WTs) struck by lightning. The equivalent circuits of blade, moving contact site, tower, and earth-termination system are built, respectively, and a set of analytic formulas are presented to evaluate their circuit parameters. By assembling the equivalent circuits of these separate parts, a complete model is set up for describing the lightning transient behavior of the WTs. Then, the transient responses can be obtained at different locations in the WT on the basis of the numerical solution to the network equations. In order to check the validity of the model, a laboratory experiment has been made on a reduced-scale WT. The model has also been applied to lightning transient analysis of an actual WT with a rated power of 2.5 MW.
Transcranial magnetic stimulation of mouse brain using high-resolution anatomical models
Authors: Crowther L. J. , Hadimani R. L. , Kanthasamy A. G. , Jiles D. C.
Published: January 2014

Transcranial magnetic stimulation (TMS) offers the possibility of non-invasive treatment of brain disorders in humans. Studies on animals can allow rapid progress of the research including exploring a variety of different treatment conditions. Numerical calculations using animal models are needed to help design suitable TMS coils for use in animal experiments, in particular, to estimate the electric field induced in animal brains. In this paper, we have implemented a high-resolution anatomical MRI-derived mouse model consisting of 50 tissue types to accurately calculate induced electric field in the mouse brain. Magnetic field measurements have been performed on the surface of the coil and compared with the calculations in order to validate the calculated magnetic and induced electric fields in the brain. Results show how the induced electric field is distributed in a mouse brain and allow investigation of how this could be improved for TMS studies using mice. The findings have important implications in further preclinical development of TMS for treatment of human diseases.
Wave-function engineering and absorption spectra in Si0.16Ge0.84/Ge0.94Sn0.06/Si0.16Ge0.84 strained on relaxed Si0.10Ge0.90 type I quantum well
Authors: Yahyaoui N. , Sfina N. , Lazzari J.-L. , Bournel A. , Said M.
Published: January 2014

We theoretically investigate germanium-tin alloy as a semiconductor for the design of near infrared optical modulators in which the Ge1−xSnx alloy is the active region. We have calculated the electronic band parameters for heterointerfaces between strained Ge1−xSnx and relaxed Si1−yGey. Then, a type-I strain-compensated Si0.10Ge0.90/Si0.16Ge0.84/Ge0.94Sn0.06 quantum well heterostructure optimized in terms of compositions and thicknesses is studied by solving Schrödinger equation without and under applied bias voltage. The strong absorption coefficient (>1.5 × 104 cm−1) and the shift of the direct transition under large Stark effect at 3 V are useful characteristics for the design of optoelectronic devices based on compressively strained IV-IV heterostructures at near infrared wavelengths.
Enhanced plasmonic Brewster transmission through metascreens by tapered slits
Authors: Le Khai Q.
Published: January 2014

The recently introduced plasmonic Brewster transmission through free-standing perforated metallic screens (metascreens), which offers ultrabroadband total light transmission has been demonstrated both theoretically and experimentally. This anomalous phenomenon is attributed to impedance matching between the guided modes supported by ultranarrow straight slits and transverse-magnetic impinging waves at a specific oblique incidence. However, this impedance matching mechanism is significantly influenced by the presence of realistic substrates leading to reduce the plasmonic Brewster transmission. To circumvent this substrate influence, the author proposes to carve periodically tapered slits on metascreens to enable the impedance matching at the input and output surface and thus enhance transmission at the Brewster angle. This finding is applied to realize ultrathin perfect absorbers with a broad bandwidth of operation.
Effect of current waveform on the performance of phosphor converted nitride light emitting diodes
Authors: Ludwiczak Bogna , Jantsch Wolfgang
Published: January 2014

We investigate the influence of the current waveform on the efficiency and the emission spectra of white, high power InGaN light emitting diodes. We consider rectangular and trapezoidal current pulses, adjusted to provide the same number of charge carriers in the space charge region. Our measurements confirm the theoretical expectation that flattening of the pulse flank increases the power efficiency. This effect is stronger according to the current amplitude. The emission blue peak at trapezoidal pulses is slightly red-shifted compared to that one at rectangular pulses. This indicates a stronger effect of the quantum confined Stark effect for trapezoidal pulse driving.
Origin of superconductivity in layered centrosymmetric LaNiGa2
Authors: Tütüncü H. M. , Srivastava G. P.
Published: January 2014

We have examined the origin of superconductivity in layered centrosymmetric LaNiGa2 by employing a linear response approach based on the density functional perturbation theory. Our results indicate that this material is a conventional electron-phonon superconductor with intermediate level of coupling strength, with the electron-phonon coupling parameter of 0.70, and the superconducting critical temperature of 1.90 K in excellent accordance with experimental value of 1.97 K. The largest contribution to the electron-phonon coupling comes from the La d and Ga p electrons near the Fermi energy and the B3g phonon branch resulting from vibrations of these atoms along the Γ-Z symmetry line in the Brillouin zone.
Magnetic properties on the surface of FeAl stripes induced by nanosecond pulsed laser irradiation
Authors: Kaiju H. , Yoshida Y. , Watanabe S. , Kondo K. , Ishibashi A. , Yoshimi K.
Published: January 2014

We demonstrate the formation of magnetic nanostripes on the surface of Fe52Al48 induced by nanosecond pulsed laser irradiation and investigate their magnetic properties. The magnetic stripe consists of a disordered A2 phase of Fe-Al alloys with Al-oxide along the [110] direction on the (111)-oriented plane. According to the focused magneto-optical Kerr effect measurement, the coercive force of the magnetic stripe obeys the 1/cos θ law, where θ is the field rotation angle estimated from the stripe direction. Also, the jump field can be observed in the magnetic hysteresis loop. These results indicate that the magnetization reversal in the magnetic stripe originates from the domain pinning, showing that the magnetization rotates incoherently.
On the nature of heat effects and shear modulus softening in metallic glasses: A generalized approach
Authors: Kobelev N. P. , Khonik V. A. , Makarov A. S. , Afonin G. V. , Mitrofanov Yu. P.
Published: January 2014

The paper presents a new approach to the nature of heat effects and shear modulus softening in metallic glasses. The approach is based on the assumption that the glass contains quenched-in “defects”—elastic dipoles. Using the nonlinear elastic representation of the internal energy of glass with quenched-in elastic dipoles, we derive a simple analytical law, which connects the heat flow and temperature derivative of the shear modulus. Specially performed experiments confirmed the validity of this law. The exothermal and endothermal heat processes in glass reveal through the relaxation of the shear modulus confirming it as a key parameter for the understanding the relaxation processes in glasses.
Photovoltaic effect of lead-free (Na0.82K0.18)0.5Bi4.5Ti4O15 ferroelectric thin film using Pt and indium tin oxide top electrodes
Authors: Seok Woo Won , Sik Won Sung , Won Ahn Chang , Chae Song A , Ullah Aman , Won Kim Ill
Published: January 2014

We have grown a Bi-layer structure (Na0.82K0.18)0.5Bi4.5Ti4O15 (NKBiT) ferroelectric thin film on Pt(111)/TiO2/SiO2/Si(100) substrate by using the chemical solution deposition method and deposited two kinds of thin Pt and indium tin oxide (ITO) top electrodes. The photovoltaic behaviors of Pt/NKBiT/Pt and ITO/NKBit/Pt capacitors were investigated over the wavelength range of 300–500 nm. When NKBiT thin film is illuminated by the corresponding wavelength of the film's energy band gap (Eg), a photocurrent is generated due to the Schottky barrier between electrode and film, and an internal electric field is originated by the depolarization field. The maximum photocurrent density and power conversion efficiency of the ITO/NKBiT/Pt capacitor in the poled-up state are obtained as 45.75 nA/cm2 and 0.035%, respectively, at 352 nm. The photocurrent density and power conversion efficiency of the ITO/NKBiT/Pt capacitor increased to 3.5 times higher than that of the Pt/NKBiT/Pt capacitor.
Lateral carrier diffusion and current gain in terahertz InGaAs/InP double-heterojunction bipolar transistors
Authors: Chiang Han-Wei , Rode Johann C. , Choudhary Prateek , Rodwell Mark J. W.
Published: January 2014

The DC current gain in In0.53Ga0.47As/InP double-heterojunction bipolar transistors is computed based on a drift-diffusion model, and is compared with experimental data. Even in the absence of other scaling effects, lateral diffusion of electrons to the base Ohmic contacts causes a rapid reduction in DC current gain as the emitter junction width and emitter-base contact spacing are reduced. The simulation and experimental data are compared in order to examine the effect of carrier lateral diffusion on current gain. The impact on current gain due to device scaling and approaches to increase current gain are discussed.