bluuebunny/crossref_metadata_2025 huggingface dataset:
Praktische Aspekte der Behandlung des idiopathischen Parkinsonsyndroms
Authors: Fuhr Peter , Gschwandtner Ute , Brunnschweiler Heiner , Taub Ethan
Published: August 2013

Bei Beginn der Parkinsonkrankheit steht die Frage der korrekten Diagnose im Vordergrund. Die Behandlung ist symptomatisch und beginnt je nach Lebensalter und neuropsychiatrischer Begleitsymptomatik mit Levodopa oder Dopaminagonisten. Bei einer Vielzahl von Medikamenteneinnahmen pro Tag oder erheblichen nicht-motorischen Problemen liegt eine komplexe Behandlungssituation vor, die immer eine individuell angepasste Behandlung erfordert, und bei der nicht-medikamentöse Therapien wichtig sind. Wird mit konservativen Mitteln nicht eine befriedigende Motorik bei noch akzeptablen Nebenwirkungen erreicht, soll im Rahmen einer umfassenden Abklärung die Möglichkeit einer tiefen Hirnstimulation evaluiert werden.
Wann sollen Pflegeheimbewohner hospitalisiert werden und wann nicht?
Authors: Bally Klaus W. , Nickel Christian
Published: August 2013

Pflegeheimbewohner werden in der Regel von den behandelnden Hausärzten notfallmässig zur stationären Behandlung in Akutkliniken und Geriatriespitäler eingewiesen. Betagte multimorbide Patienten erleben Hospitalisationen oftmals als belastend; nicht selten führen Spitalaufenthalte bei diesem sehr vulnerablen Kollektiv zu substantiellen Verschlechterungen ihrer kognitiven Leistungen und ihrer noch vorhandenen Selbständigkeit. Indikationen für Spitaleinweisungen aus dem Pflegeheim sind Infekte, Exazerbationen von vorbestehenden Herz-Kreislauferkrankungen und Folgen von Stürzen. Die Verfügbarkeit von Ärzten und qualifiziertem Pflegepersonal, rechtzeitiges Erkennen gefährlicher abwendbarer Verläufe und adäquates Management von chronischen Erkrankungen sind wesentliche Voraussetzungen, um unnötige Hospitalisationen zu vermeiden. Zudem gehört es zu den hausärztlichen Aufgaben, eine Palliativsituation rechtzeitig als solche zu erfassen sowie den Patientenwunsch bezüglich Spitaleinweisung und Sterbeort zu kennen.
Was der Internist über Schrittmacher wissen muss
Authors: Nüssli Dominique , Schär Beat
Published: August 2013

In der Schweiz wurde im Jahre 2011 bei 4463 Patienten ein Herzschrittmacher (Pacemaker, PM) neu implantiert. Diese Übersichtsarbeit geht auf die prinzipiellen Schrittmacherfunktionen, einige grundsätzlichen Bemerkungen zur Herzschrittmachertherapie und vor allem auf die in der Praxis wesentlichen Indikationen und die dafür verwendeten Schrittmachertypen ein. Die aktuell gültigen Richtlinien zur PM-Indikation stammen aus dem Jahre 2007 [1], bzw. 2008 [2] und bilden die Grundlage dieses Artikels, wobei bewusst sehr seltene Indikationen (kongenitale Vitien, Bradykardien nach Herztransplantation, etc.) nicht berücksichtigt werden. Jedes Jahr kommen neue Schrittmachermodelle auf den Markt, die zwar erweiterte Diagnostikmöglichkeiten bieten (z. B. genaue Frequenzspeicher, 1:1 EKG-Aufzeichnungen), im praktischen Alltag aber nicht wesentliche Veränderungen mit sich bringen. Eine Neuerung mit klinischer Konsequenz sind die seit etwa einem Jahr erhältlichen MRI-«sicheren»-Systeme, auf die in diesem Artikel speziell eingegangen wird.
Comparison of CO2 in Air Versus Carbogen for the Measurement of Cerebrovascular Reactivity with Magnetic Resonance Imaging
Authors: Hare Hannah V , Germuska Michael , Kelly Michael E , Bulte Daniel P
Published: August 2013

Measurement of cerebrovascular reactivity (CVR) can give valuable information about existing pathology and the risk of adverse events, such as stroke. A common method of obtaining regional CVR values is by measuring the blood flow response to carbon dioxide (CO2)-enriched air using arterial spin labeling (ASL) or blood oxygen level-dependent (BOLD) imaging. Recently, several studies have used carbogen gas (containing only CO2 and oxygen) as an alternative stimulus. A direct comparison was performed between CVR values acquired by ASL and BOLD imaging using stimuli of (1) 5% CO2 in air and (2) 5% CO2 in oxygen (carbogen-5). Although BOLD and ASL CVR values are shown to be correlated for CO2 in air (mean response 0.11 ± 0.03% BOLD, 4.46 ± 1.80% ASL, n = 16 hemispheres), this correlation disappears during a carbogen stimulus (0.36 ± 0.06% BOLD, 4.97 ± 1.30% ASL). It is concluded that BOLD imaging should generally not be used in conjunction with a carbogen stimulus when measuring CVR, and that care must be taken when interpreting CVR as measured by ASL, as values obtained from different stimuli (CO2 in air versus carbogen) are not directly comparable.
The Role of Parl and HtrA2 in Striatal Neuronal Injury After Transient Global Cerebral Ischemia
Authors: Yoshioka Hideyuki , Katsu Masataka , Sakata Hiroyuki , Okami Nobuya , Wakai Takuma , Kinouchi Hiroyuki , Chan Pak H
Published: August 2013

The presenilin-associated rhomboid-like (PARL) protein and high temperature requirement factor A2 (HtrA2) are key regulators of mitochondrial integrity and play pivotal roles in apoptosis. However, their roles after cerebral ischemia have not been thoroughly elucidated. To clarify these roles, mice were subjected to transient global cerebral ischemia, and striatal neuronal injury was assessed. Western blot and coimmunoprecipitation analyses revealed that PARL and processed HtrA2 localized to mitochondria, and that PARL was bound to HtrA2 in sham animals. Expression of PARL and processed HtrA2 in mitochondria significantly decreased 6 to 72 hours after ischemia, and the binding of PARL to HtrA2 disappeared after ischemia. In contrast, expression of processed HtrA2 increased 24 hours after ischemia in the cytosol, where HtrA2 was bound to X chromosome-linked inhibitor-of-apoptosis protein (XIAP). Administration of PARL small interfering RNA inhibited HtrA2 processing and worsened ischemic neuronal injury. Our results show that downregulation of PARL after ischemia is a key step in ischemic neuronal injury, and that it decreases HtrA2 processing and increases neuronal vulnerability. In addition, processed HtrA2 released into the cytosol after ischemia contributes to neuronal injury via inhibition of XIAP.
Multi-stimuli responsive polymers – the all-in-one talents
Authors: Schattling Philipp , Jochum Florian D. , Theato Patrick
Published: August 2013

The integration of several responsive moieties within one polymer yields smart polymers exhibiting a multifaceted responsive behaviour.
Selective O-acyl ring-opening of β-butyrolactone catalyzed by trifluoromethane sulfonic acid: application to the preparation of well-defined block copolymers
Authors: Couffin Aline , Martín-Vaca Blanca , Bourissou Didier , Navarro Christophe
Published: August 2013

HOTf catalyzes ring-opening of β-butyrolactone selectively via O-acyl bond cleavage, enabling efficient copolymerization.
The Contribution of Matched Envelope Dynamic Range to the Binaural Benefits in Simulated Bilateral Electric Hearing
Authors: Chen Fei , Wong Lena L. N. , Qiu Jianxin , Liu Yehai , Azimi Behnam , Hu Yi
Published: August 2013

Purpose

This study examined the effects of envelope dynamic-range mismatch on the intelligibility of Mandarin speech in noise by simulated bilateral electric hearing.

Method

Noise-vocoded Mandarin speech, corrupted by speech-shaped noise at 5 and 0 dB signal-to-noise ratios, was presented unilaterally or bilaterally to 10 normal-hearing listeners for recognition. For unilateral conditions, the right ear was presented with the 8-channel noise-vocoded stimuli generated using a 15-dB envelope dynamic range (DR). To simulate the envelope DR mismatch between the 2 ears, the left ear was presented with the 8-channel noise-vocoded stimuli generated using a 5-, 10-, or 15-dB envelope DR, respectively.

Results

Significant binaural summation benefits for Mandarin speech recognition were observed only with matched envelope DR between the 2 ears. With reduced DR, the performance of tone identification was more consistent in the steady-state speech-shaped noise than that of sentence recognition.

Conclusions

Consistent with previous findings, the present results suggest that Mandarin speech-perception performance of bilateral electric listening in noise is affected by the difference of envelope DR between the 2 implanted ears, and the binaural summation benefits are maximized when DR mismatch is minimized between the 2 implanted ears.
Aspects of current geothermal application in Bulgaria
Authors: Bojadgieva Klara , Benderev Aleksey , Berova-Andonova Adriana , Tsanov Tsanko
Published: August 2013

The territory of Bulgaria is rich in thermal water of temperature in the range of 20 °C–100 °C. Electricity generation from geothermal water is not currently available in the country. Direct thermal water use nowadays is mainly for balneology, space heating and air-conditioning, greenhouse heating, geothermal ground source heat pumps (GSHP), direct thermal water supply, and bottling of potable water and soft drinks. Several applications such as balneology and geothermal ground source heat pumps show more stable development in the current period, while geothermal energy used for heating of buildings and greenhouses has considerably decreased. The update information on hydrothermal fields is based on issued permits and concessions by the state since 2000 and concerns mainly state-owned hydrothermal fields. The current installed capacity amounts to about 85.8 MW (excl. GSHP). A progress has been recently made in the state policy promoting thermal water utilization. According to the latest amendments of the Water Act taxes for thermal water application are considerably reduced, and many state-owned reservoirs are made available for use by the municipalities.
Stability and orientation of lamellae in diblock copolymer films
Authors: Weith Vanessa , Krekhov Alexei , Zimmermann Walter
Published: August 2013

The dynamics of microphase separation and the orientation of lamellae in diblock copolymers are investigated in terms of a mean-field model. The formation of lamellar structures and their stable states are explored and it is shown that lamellae are stable not only for the period of the structure corresponding to the minimum of the free energy. The range of wavelengths of stable lamellae is determined by an efficient functional approach introduced with this work. The effects of the interaction of diblock copolymers with two confining substrates on the lamellae orientation are studied by an extensive analysis of the total free energy. By changing the wetting property at one boundary, a transition from a preferentially perpendicular to a parallel lamellar orientation with respect to the confining plates is found, which is rather independent of the distance between the boundaries. Simulations of the dynamics of microphase separation reveal that the time scale of the lamellar orientational order dynamics, which is quantitatively characterized in terms of an orientational order parameter and the structure factor, depends significantly on the properties of the confining boundaries as well as on the quench depth.
Thermodynamic and structural signatures of water-driven methane-methane attraction in coarse-grained mW water
Authors: Song Bin , Molinero Valeria
Published: August 2013

Hydrophobic interactions are responsible for water-driven processes such as protein folding and self-assembly of biomolecules. Microscopic theories and molecular simulations have been used to study association of a pair of methanes in water, the paradigmatic example of hydrophobic attraction, and determined that entropy is the driving force for the association of the methane pair, while the enthalpy disfavors it. An open question is to which extent coarse-grained water models can still produce correct thermodynamic and structural signatures of hydrophobic interaction. In this work, we investigate the hydrophobic interaction between a methane pair in water at temperatures from 260 to 340 K through molecular dynamics simulations with the coarse-grained monatomic water model mW. We find that the coarse-grained model correctly represents the free energy of association of the methane pair, the temperature dependence of free energy, and the positive change in entropy and enthalpy upon association. We investigate the relationship between thermodynamic signatures and structural order of water through the analysis of the spatial distribution of the density, energy, and tetrahedral order parameter Qt of water. The simulations reveal an enhancement of tetrahedral order in the region between the first and second hydration shells of the methane molecules. The increase in tetrahedral order, however, is far from what would be expected for a clathrate-like or ice-like shell around the solutes. This work shows that the mW water model reproduces the key signatures of hydrophobic interaction without long ranged electrostatics or the need to be re-parameterized for different thermodynamic states. These characteristics, and its hundred-fold increase in efficiency with respect to atomistic models, make mW a promising water model for studying water-driven hydrophobic processes in more complex systems.
A study of vertical and in-plane electron mobility due to interface roughness scattering at low temperature in InAs/GaSb type-II superlattices
Authors: Safa S. , Asgari A. , Faraone L.
Published: August 2013

In this paper, we present a study of the effects of different superlattice structural parameters on the bandgap and on both the vertical and in-plane mobility of electrons in InAs/GaSb type-II superlattices using a fully numerical finite difference method. The analysis of our results clearly indicates the significance of interface roughness scattering and, in particular, that the influence of interface roughness correlation length and height is considerable. A comparison of our calculated results with published experimental data is shown to be in good agreement.
Fundamental properties of light-emitting liquid crystal cells operated under alternating voltage
Authors: Honma Michinori , Horiuchi Takao , Nose Toshiaki
Published: August 2013

We have investigated the fundamental operation characteristics of light-emitting liquid crystals with an emissive layer of fluorescent dye-doped nematic liquid crystal under the condition of applied AC voltage. The electric field dependent current and luminance properties for different frequencies are satisfactorily explained by an equivalent circuit analysis. We confirm that the luminance steeply plunges as the frequency increases. Such a great suppression is explained by accounting for the cut-off properties of the equivalent circuit and for the effect of ions drift mobility.
Investigation of attractive and repulsive interactions associated with ketones in supercritical CO2, based on Raman spectroscopy and theoretical calculations
Authors: Kajiya Daisuke , Saitow Ken-ichi
Published: August 2013

Carbonyl compounds are solutes that are highly soluble in supercritical CO2 (scCO2). Their solubility governs the efficiency of chemical reactions, and is significantly increased by changing a chromophore. To effectively use scCO2 as solvent, it is crucial to understand the high solubility of carbonyl compounds, the solvation structure, and the solute–solvent intermolecular interactions. We report Raman spectroscopic data, for three prototypical ketones dissolved in scCO2, and four theoretical analyses. The vibrational Raman spectra of the C=O stretching modes of ketones (acetone, acetophenone, and benzophenone) were measured in scCO2 along the reduced temperature Tr = T/Tc = 1.02 isotherm as a function of the reduced density ρr = ρ/ρc in the range 0.05–1.5. The peak frequencies of the C=O stretching modes shifted toward lower energies as the fluid density increased. The density dependence was analyzed by using perturbed hard-sphere theory, and the shift was decomposed into attractive and repulsive energy components. The attractive energy between the ketones and CO2 was up to nine times higher than the repulsive energy, and its magnitude increased in the following order: acetone < acetophenone < benzophenone. The Mulliken charges of the three solutes and CO2 molecules obtained by using quantum chemistry calculations described the order of the magnitude of the attractive energy and optimized the relative configuration between each solute and CO2. According to theoretical calculations for the dispersion energy, the dipole-induced-dipole interaction energy, and the frequency shift due to their interactions, the experimentally determined attractive energy differences in the three solutes were attributed to the dispersion energies that depended on a chromophore attached to the carbonyl groups. It was found that the major intermolecular interaction with the attractive shift varied from dipole-induced dipole to dispersion depending on the chromophore in the ketones in scCO2. As the common conclusion for the Raman spectral measurements and the four theoretical calculations, solute polarizability, modified by the chromophore, was at the core of the solute–solvent interactions of the ketones in scCO2.
Spherical seed mediated vapor condensation of Lennard-Jones fluid: A density functional theory approach
Authors: Ghosh Satinath , Ghosh Swapan K.
Published: August 2013

Vapor to liquid condensation in presence of spherical seed particle of any arbitrary radius ranging from zero to infinity has been investigated using density functional theory, by modeling the local Helmholtz free energy density functional as well as the density profile at the vapor-liquid interface. A general theory is, thus, obtained which provides the different modes of nucleation based on the size of the seed ranging from zero (corresponding to the homogeneous mode of nucleation) to infinity (corresponding to the heterogeneous nucleation on flat surface). The theory is applied to the Lennard-Jones fluid and the optimized shape (i.e., contact angle) and formation free energy of droplets of any arbitrary size have been obtained in this work. The change of the shape (optimized) with the variation of the size of the liquid droplet as well as with the size of the solid substrate has been studied, thus predicting the shape-size relationship in the course of vapor to liquid heterogeneous nucleation on a spherical solid substrate of any particular size. The spinodal decomposition of vapor has also been observed at higher strength of the solid-fluid interaction. The results have been compared with the results of the conventional classical nucleation theory.
When is the next extending of Fick-Jacobs equation necessary?
Authors: Kalinay Pavol
Published: August 2013

Applicability of the effective one-dimensional equations, such as Fick-Jacobs equation and its extensions, describing diffusion of particles in 2D or 3D channels with varying cross section A(x) along the longitudinal coordinate x, is studied. The leading nonstationary correction to Zwanzig-Reguera-Rubí equation [R. Zwanzig, J. Phys. Chem. 96, 3926 (1992)10.1021/j100189a004; D. Reguera and J. M. Rubí, Phys. Rev. E 64, 061106 (2001)10.1103/PhysRevE.64.061106] is derived and tested on the exactly solvable model, diffusion in a 2D linear cone. The effects of such correction are demonstrated and discussed on elementary nonstationary processes, a time dependent perturbation of the stationary flow and calculation of the mean first passage time.
Digital time-resolved optical measurement of discharge currents in long air gaps
Authors: Yue Yi-shi , He Jun-jia
Published: August 2013

Shortcomings in the dynamic range and the frequency bandwidth of current diagnostic methods mean that measurement of the time-resolved discharge current in a long air gap discharge is still a serious problem. This work presents data from a novel discharge current sensor that takes the parameters required to determine the accuracy of the current measurement into account. The design of a coaxial current sensor with ±0.7% accuracy and a bandwidth of 75 MHz is presented. A digital optical fiber transmission system with a bandwidth that exceeds 100 MHz is used to transmit the signal. To demonstrate the efficiency of the whole system, experiments using a rod-plane discharge geometry with 2 m and 4 m air gap lengths are performed to analyze the measured current data in comparison with that taken from synchronized high-speed photographs. The results demonstrate that the investigated experimental set-up improves substantially the understanding of the fundamental mechanisms of long air gap discharges.
Multiscale enhanced path sampling based on the Onsager-Machlup action: Application to a model polymer
Authors: Fujisaki Hiroshi , Shiga Motoyuki , Moritsugu Kei , Kidera Akinori
Published: August 2013

We propose a novel path sampling method based on the Onsager-Machlup (OM) action by generalizing the multiscale enhanced sampling technique suggested by Moritsugu and co-workers [J. Chem. Phys. 133, 224105 (2010)10.1063/1.3510519]. The basic idea of this method is that the system we want to study (for example, some molecular system described by molecular mechanics) is coupled to a coarse-grained (CG) system, which can move more quickly and can be computed more efficiently than the original system. We simulate this combined system (original + CG system) using Langevin dynamics where different heat baths are coupled to the two systems. When the coupling is strong enough, the original system is guided by the CG system, and is able to sample the configuration and path space with more efficiency. We need to correct the bias caused by the coupling, however, by employing the Hamiltonian replica exchange, where we prepare many path replicas with different coupling strengths. As a result, an unbiased path ensemble for the original system can be found in the weakest coupling path ensemble. This strategy is easily implemented because a weight for a path calculated by the OM action is formally the same as the Boltzmann weight if we properly define the path “Hamiltonian.” We apply this method to a model polymer with Asakura-Oosawa interaction, and compare the results with the conventional transition path sampling method.
Ruling out the impact of defects on the below band gap photoconductivity of Ti supersaturated Si
Authors: Olea J. , Pastor D. , del Prado A. , García-Hemme E. , García-Hernansanz R. , Mártil I. , González-Díaz G.
Published: August 2013

In this study, we present a structural and optoelectronic characterization of high dose Ti implanted Si subsequently pulsed-laser melted (Ti supersaturated Si). Time-of-flight secondary ion mass spectrometry analysis reveals that the theoretical Mott limit has been surpassed after the laser process and transmission electron microscopy images show a good lattice reconstruction. Optical characterization shows strong sub-band gap absorption related to the high Ti concentration. Photoconductivity measurements show that Ti supersaturated Si presents spectral response orders of magnitude higher than unimplanted Si at energies below the band gap. We conclude that the observed below band gap photoconductivity cannot be attributed to structural defects produced by the fabrication processes and suggest that both absorption coefficient of the new material and lifetime of photoexcited carriers have been enhanced due to the presence of a high Ti concentration. This remarkable result proves that Ti supersaturated Si is a promising material for both infrared detectors and high efficiency photovoltaic devices.
A deep optical cavity trap for atoms and molecules with rapid frequency and intensity modulation
Authors: Edmunds P. D. , Barker P. F.
Published: August 2013

We describe a deep far-off resonance trap for metastable argon atoms utilizing a medium finesse cavity and a high input power (30 W) to produce trap depths of up to 11 mK. The depth can be rapidly modulated allowing efficient loading of the trap, characterization of trapped atom temperature, and reduction of intensity noise. We measure the change in radius of curvature of the mirrors due to heating by the high circulating intensity and show that trapping is not adversely effected by this for all input powers.
Absolute cross section for loss of supercoiled topology induced by 10 eV electrons in highly uniform /DNA/1,3-diaminopropane films deposited on highly ordered pyrolitic graphite
Authors: Boulanouar Omar , Fromm Michel , Bass Andrew D. , Cloutier Pierre , Sanche Léon
Published: August 2013

It was recently shown that the affinity of doubly charged, 1-3 diaminopropane (Dap2+) for DNA permits the growth on highly ordered pyrolitic graphite (HOPG) substrates, of plasmid DNA films, of known uniform thickness [O. Boulanouar, A. Khatyr, G. Herlem, F. Palmino, L. Sanche, and M. Fromm, J. Phys. Chem. C 115, 21291–21298 (2011)]. Post-irradiation analysis by electrophoresis of such targets confirms that electron impact at 10 eV produces a maximum in the yield of single strand breaks that can be associated with the formation of a DNA− transient anion. Using a well-adapted deterministic survival model for the variation of electron damage with fluence and film thickness, we have determined an absolute cross section for strand-break damage by 10 eV electrons and inelastic scattering attenuation length in DNA-Dap complex films.
Influence of anisotropic ion shape on structure and capacitance of an electric double layer: A Monte Carlo and density functional study
Authors: Lamperski Stanisław , Kaja Monika , Bhuiyan Lutful Bari , Wu Jianzhong , Henderson Douglas
Published: August 2013

The effect of anisotropic ion shapes on the structure and the differential capacitance of an electric double layer in the electrolyte solution regime is studied using the density functional theory and Monte Carlo simulations. The double layer is modelled by a uniformly charged, non-polarizable planar electrode next to an electrolyte where the cation is a dimer consisting of two tangentially touching rigid spheres one of which is positively charged while the other is neutral, the anion is a negatively charged rigid sphere, and the solvent is a dielectric continuum. Numerical results are reported for monovalent electrolytes at room temperature for a series of electrolyte concentrations and varying electrode surface charge densities. Asymmetry in ionic shape leads to more structure near the electrode when its charge is opposite to that of the non-spherical ions. Overall, the theoretically predicted density and mean electrostatic profiles reproduce the corresponding simulation results to a very good degree. The asymmetry of the ion shape also yields asymmetry in the differential capacitance curve plotted as a function of the electrode charge density. The differential capacity evolves from being distorted bactrian camel-shaped (a minimum flanked by a maximum on either side) at low electrolyte concentrations to being bell-like (a single broad maximum) at higher concentrations. The theoretical capacitance results again agree well with the simulations.
A new perspective on correlated polyelectrolyte adsorption: Positioning, conformation, and patterns
Authors: Nunes Sandra C. C. , Cova Tânia F. G. G. , Pais A. A. C. C.
Published: August 2013

This work focuses on multiple chain deposition, using a coarse-grained model. The phenomenon is assessed from a novel perspective which emphasizes the conformation and relative arrangement of the deposited chains. Variations in chain number and length are considered, and the surface charge in the different systems ranges from partially neutralized to reversed by backbone deposition. New tools are proposed for the analysis of these systems, in which focus is given to configuration-wise approaches that allow the interpretation of correlated multi-chain behavior. It is seen that adsorption occurs, with a minimal effect upon the bulk conformation, even when overcharging occurs. Also, chain ends create a lower electrostatic potential, which makes them both the least adsorbed region of the backbone, and the prevalent site of closer proximity with other chains. Additionally, adsorption into the most favorable region of the surface overrides, to a large degree, interchain repulsion.
Equivalence of chain conformations in the surface region of a polymer melt and a single Gaussian chain under critical conditions
Authors: Skvortsov A. M. , Leermakers F. A. M. , Fleer G. J.
Published: August 2013

In the melt polymer conformations are nearly ideal according to Flory's ideality hypothesis. Silberberg generalized this statement for chains in the interfacial region. We check the Silberberg argument by analyzing the conformations of a probe chain end-grafted at a solid surface in a sea of floating free chains of concentration φ by the self-consistent field (SCF) method. Apart from the grafting, probe chain and floating chains are identical. Most of the results were obtained for a standard SCF model with freely jointed chains on a six-choice lattice, where immediate step reversals are allowed. A few data were generated for a five-choice lattice, where such step reversals are forbidden. These coarse-grained models describe the equilibrium properties of flexible atactic polymer chains at the scale of the segment length. The concentration was varied over the whole range from φ = 0 (single grafted chain) to φ = 1 (probe chain in the melt). The number of contacts with the surface, average height of the free end and its dispersion, average loop and train length, tail size distribution, end-point and overall segment distributions were calculated for a grafted probe chain as a function of φ, for several chain lengths and substrate/polymer interactions, which were varied from strong repulsion to strong adsorption. The computations show that the conformations of the probe chain in the melt do not depend on substrate/polymer interactions and are very similar to the conformations of a single end-grafted chain under critical conditions, and can thus be described analytically. When the substrate/polymer interaction is fixed at the value corresponding to critical conditions, all equilibrium properties of a probe chain are independent of φ, over the whole range from a dilute solution to the melt. We believe that the conformations of all flexible chains in the surface region of the melt are close to those of an appropriate single chain in critical conditions, provided that one end of the single chain is fixed at the same point as a chain in the melt.
Four families of Weyl group orbit functions of B3 and C3
Authors: Háková Lenka , Hrivnák Jiří , Patera Jiří
Published: August 2013

The properties of the four families of special functions of three real variables, called here C-, S-, Ss-, and Sl-functions, are studied. The Ss- and Sl-functions are considered in all details required for their exploitation in Fourier expansions of digital data, sampled on finite fragment of lattices of any density and of the 3D symmetry imposed by the weight lattices of B3 and C3 simple Lie algebras/groups. The continuous interpolations, which are induced by the discrete expansions, are exemplified and compared for some model functions.
Weierstrass traveling wave solutions for dissipative Benjamin, Bona, and Mahony (BBM) equation
Authors: Mancas Stefan C. , Spradlin Greg , Khanal Harihar
Published: August 2013

In this paper the effect of a small dissipation on waves is included to find exact solutions to the modified Benjamin, Bona, and Mahony (BBM) equation by viscosity. Using Lyapunov functions and dynamical systems theory, we prove that when viscosity is added to the BBM equation, in certain regions there still exist bounded traveling wave solutions in the form of solitary waves, periodic, and elliptic functions. By using the canonical form of Abel equation, the polynomial Appell invariant makes the equation integrable in terms of Weierstrass ℘ functions. We will use a general formalism based on Ince's transformation to write the general solution of dissipative BBM in terms of ℘ functions, from which all the other known solutions can be obtained via simplifying assumptions. Using ODE (ordinary differential equations) analysis we show that the traveling wave speed is a bifurcation parameter that makes transition between different classes of waves.
Pressure effect on vibrational frequency and dephasing of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids
Authors: Pison L. , Costa Gomes M. F. , Pádua A. A. H. , Andrault D. , Norman S. , Hardacre C. , Ribeiro M. C. C.
Published: August 2013

Raman spectra in the range of the totally symmetric stretching mode of the [PF6]− anion, νs(PF6), have been measured for 1-alkyl-3-methylimidazolium ionic liquids [CnC1im][PF6], for n = 4, 6, and 8, as a function of pressure at room temperature. The ionic liquids [C6C1im][PF6] and [C8C1im][PF6] remain in an amorphous phase up to 3.5 GPa, in contrast to [C4C1im][PF6], which crystallizes above ∼0.5 GPa. Equations of state based either on a group contribution model or Carnahan-Starling-van der Waals model have been used to estimate the densities of the ionic liquids at high pressures. The shifts of the vibrational frequency of νs(PF6) with density observed in [C6C1im][PF6] and in [C8C1im][PF6] have been calculated by a hard-sphere model of a pseudo-diatomic solute under short-range repulsive interactions with the neighboring particles. The stochastic model of Kubo for vibrational dephasing has been used to obtain the amplitude of vibrational frequency fluctuation, ⟨Δω2⟩, and the relaxation time of frequency fluctuation, τc, as a function of density by Raman band shape analysis of the νs(PF6) mode of [C6C1im][PF6] and [C8C1im][PF6].
Effect of local coordination of Mn on Mn-L2,3 edge electron energy loss spectrum
Authors: Nishida Shuji , Kobayashi Shunsuke , Kumamoto Akihito , Ikeno Hidekazu , Mizoguchi Teruyasu , Tanaka Isao , Ikuhara Yuichi , Yamamoto Takahisa
Published: August 2013

The effects of the local coordination environment of Mn ions in perovskite manganese oxides on the Mn-L2,3 edge electron energy loss (EEL) spectra was experimentally and theoretically investigated. The Mn-L2,3 edge EEL spectra were observed for various perovskite manganese oxides, including YMnO3, LaMnO3, BaMnO3, SrMnO3, and CaMnO3, in which the Mn ions have different valence states and local coordination. The experiment revealed that the Mn L3/L2 ratio is influenced not only by the valence state but also by the local environment of the Mn ions. Furthermore, compared to the Mn L3/L2 ratios of Mn3+ compounds, the Mn L3/L2 ratios of the Mn4+ compounds are found to be much more sensitive to local distortions. The ab-initio multiplet calculation of the Mn-L2,3 edge EEL spectra revealed that the effects of local coordination on the spectral features are dependent on the local electronic structures of the Mn ions. These findings indicate that the valence state as well as the local environments of the Mn ions can be unraveled by combining experimental and theoretical investigations of Mn-L2,3 edge EEL spectra.
Strained hetero interfaces in Si/SiGe/SiGe/SiGe multi-layers studied by scanning moiré fringe imaging
Authors: Kim Suhyun , Lee Sungho , Kondo Yukihito , Lee Kyungwoo , Byun Gwangsun , Lee Sunyoung , Lee Kyupil
Published: August 2013

Nanometer-scale scanning moiré fringes (SMFs) of the hetero interfaces in Si/Si1−xGex/Si1−xGex/Si1−xGex multi-layers have been obtained by high-angle annular dark field scanning transmission electron microscope. The SMFs that appeared at each interface were commensurate, when the layers had no defects from epitaxial growth. The SMF images showed that the Si substrate at the interface was tensilely strained, and it was measured to be 0.2% relative to the unstrained Si substrate. In addition, it was found that the (220) lattice plane of the Si1−xGex layers was linearly increased with a gradient of 0.015%/nm in grown direction of [001].
A methylene bridged bisimidazolium iodide based low-volatility electrolyte for efficient dye-sensitized solar cells
Authors: Tai Qidong , Bu Chenghao , Chen Bolei , Zhang Nangang , Bai Sihang , Hu Hao , Xu Sheng , Zhao Xingzhong
Published: August 2013

In this paper, we demonstrate that 1,1′-methylene bis(3-n-methylimidazolium) diiodide (MMIDI) can be used as an excellent alternative iodide source to conventional lithium iodide (LiI) in electrolyte for dye-sensitized solar cell (DSSC). The MMIDI is cheaper and shows much improved physical and chemical stability compared to LiI. Noticeably, smaller charge transfer resistance for the reduction of triiodide and longer electron lifetime are found in the DSSCs based on MMIDI electrolyte, which result in a 23% higher overall conversion efficiency (5.26%) than that based on LiI electrolyte (4.27%). When the initial MMIDI electrolyte is optimized with functional additives, a promising 6.24% conversion efficiency is achieved.
Defecting controllability of bombarding graphene with different energetic atoms via reactive force field model
Authors: Liu Xiao Yi , Wang Feng Chao , Park Harold S. , Wu Heng An
Published: August 2013

We study the bombardment of a suspended monolayer graphene sheet via different energetic atoms via classical molecular dynamics based on the reactive force field (ReaxFF). We find that the probability, quality, and controllability of defects are mainly determined by the impact site, the properties of the incident atom, and the incident energy. Through comparison with density functional theory calculations, we demonstrate that defects and vacancies in graphene form only in regions of sufficiently high electron density. Furthermore, the quality of defects is influenced by the bond order of the incident atom-carbon bonds, where a higher bond order leads to lower probability of pristine defects (vacancies) but a higher probability of direct-substitution. Finally, the incident energy plays an important role on the evolution and final pattern of defects in graphene. Based on the probability, quality, and controllability analysis performed, we depict a full-range energy spectrum for atomic bombardment, where we demonstrate that desirable defects such as single vacancies and direct-substitution can be created with the appropriate incident energy.
Theoretical prediction of universal curves for carrier transport in Si/SiO2(100) interfaces
Authors: Ishihara Takamitsu , Kato Koichi
Published: August 2013

Atomic structure dependence of carrier transport in Si/SiO2 interface has been extensively studied. It is shown by first-principles calculations that a strong Si-O dipole is formed at the interface, and the polarized interface Si-O dipole becomes the origin of the dipole scattering. A physics-based dipole scattering model, which considers the inelastic scattering due to the vibrated dipole as well as the elastic scattering, is proposed. In particular, it is found that Si atom that forms the Si-O dipole vibrates parallel to the interface and becomes the origin of the inelastic dipole scattering. By performing the mobility calculation based on relaxation-time approximation, it is shown that the interface Si-O dipole has a significant influence on the carrier mobility in the inversion layer, and that the interface Si-O dipole scattering is one of the main scattering components that limit the carrier transport in the inversion layer, in addition to the conventional scattering components: the substrate impurity scattering, the bulk phonon scattering, and the surface roughness scattering. Upon incorporation of the Si-O dipole scattering, universal curves have been fully predicted.
Si nanocrystal-based triple-layer anti-reflection coating for Si solar cells
Authors: Zhang Jun , Chen T. P. , Liu Yang , It Wong Jen
Published: August 2013

A triple-layer anti-reflection coating (TL-ARC) with Si nanocrystals (nc-Si)-dielectric nanocomposite thin film structure is proposed for Si solar cells. The TL-ARC has a graded refractive index (RI) profile of high RI, medium RI, and low RI. Such RI profile is achieved with the structure consisting of a Si3N4 layer embedded with high concentration of nc-Si and another Si3N4 layer embedded with low concentration of nc-Si and a SiO2 layer. The design of the TL-ARC is carried out with the calculation of the effective indices of the high-RI and medium-RI layers with the Maxwell-Garnett effective medium approximation model. Due to the photoluminescence properties of nc-Si embedded in Si3N4 matrix, the TL-ARC has the inherent capability of down-converting ultraviolet photons to low-energy photons that are useful to Si solar cells. The deposition of the TL-ARC on Si solar cell is fabricated with plasma enhanced chemical vapor deposition in a single process step. The performance enhancement of Si solar cells by the TL-ARC has been demonstrated by experiments.
Enhanced biocompatibility for plasmid DNA on patterned TiO2 surfaces
Authors: Majumder Subrata , Mishra I. , Subudhi U. , Varma Shikha
Published: August 2013

An enhanced biocompatibility from nanodot patterned TiO2 surfaces, fabricated by ion beam sputtering, has been observed here through its interaction with plasmid DNA. Investigations of the persistence length and the areal conformation of DNA show that the biocompatibility increases with ion fluence. Presence of nanostructures and increased surface roughness, in conjugation with higher oxygen vacancy sites that promote charge transfer from DNA moiety, are responsible for the increased hydrophilicity and biocompatibility of the patterned surfaces.
Biopolymer as an electron selective layer for inverted polymer solar cells
Authors: Jin Tan Mein , Zhong Shu , Wang Rui , Zhang Zhongxing , Chellappan Vijila , Chen Wei
Published: August 2013

In this work, a solution-processable electron selective layer is introduced for inverted polymer solar cells (PSCs). Cationic biopolymer poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) is used as a solution-processable work function modifier of indium-tin-oxide transparent conducting electrode to yield efficient inverted PSCs of 3.3% under AM1.5G illumination, with poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester as the active layer. Devices using PDMAEMA exhibit greater stability in ambient “working conditions” as compared to devices using ZnO, retaining 90% of peak power conversion efficiency after 8 weeks. Therefore, PDMAEMA has great potential as a universal work function modifier material with high robustness.
Simulation of sub-kBT bit-energy operation of adiabatic quantum-flux-parametron logic with low bit-error-rate
Authors: Takeuchi N. , Yamanashi Y. , Yoshikawa N.
Published: August 2013

Adiabatic quantum-flux-parametron (AQFP) logic can achieve high energy-efficiency. The bit energy and bit-error-rate (BER) of AQFP gates with under-damped Josephson junctions were simulated. The results indicate that the bit energy reaches 12 yJ, which is only 20% of the thermal energy at 4.2 K, using unshunted 50-μA junctions and excitation currents with a rise/fall time of 2000 ps. Although the bit energy is extremely small, the bias margin, where the BER is less than 10−23, is approximately ±22%. These results indicate there is no minimum energy limitation for the operation of AQFP gates unless the entropy of the system decreases.
Initial carrier-envelope phase of few-cycle pulses determined by terahertz emission from air plasma
Authors: Xu Rongjie , Bai Ya , Song Liwei , Liu Peng , Li Ruxin , Xu Zhizhan
Published: August 2013

The evolution of THz waveform generated in air plasma provides a sensitive probe to the variation of the carrier envelope phase (CEP) of propagating intense few-cycle pulses. Our experimental observation and calculation reveal that the number and positions of the inversion of THz waveform are dependent on the initial CEP, which is near 0.5π constantly under varied input pulse energies when two inversions of THz waveform in air plasma become one. This provides a method of measuring the initial CEP in an accuracy that is only limited by the stability of the driving few-cycle pulses.
Thermal decomposition of silver acetate in silver paste for solar cell metallization: An effective route to reduce contact resistance
Authors: Jun Kim Suk , Yun Kim Se , Man Park Jin , Hwan Park Keum , Ho Lee Jun , Mock Lee Sang , Taek Han In , Hyang Kim Do , Ram Lim Ka , Tae Kim Won , Cheol Park Ju , Soo Jee Sang , Lee Eun-Sung
Published: August 2013

A screen printed silver/metallic glass (MG) paste formulated with Ag acetate resulted in a specific contact resistance in the range of 0.6–0.7 mΩ·cm2 on both the n- and p-type Si emitters of interdigitated back-contact solar cells. Silver nanocrystallites resulting from thermally decomposed Ag acetate prevented the Al MG frits from directly interacting with the Si emitter, thus reducing the amount of Al diffused into the Si emitters, and subsequently, the contact resistance. A photovoltaic conversion efficiency of 20.3% was achieved using this technique.
Broadband enhancement and inhibition of single quantum dot emission in plasmonic nano-cavities operating at telecommunications wavelengths
Authors: Elvira David , Braive Rémy , Beaudoin Grégoire , Sagnes Isabelle , Hugonin Jean-Paul , Abram Izo , Robert-Philip Isabelle , Lalanne Philippe , Beveratos Alexios
Published: August 2013

A plasmonic microcavity providing broadband control of spontaneous emission for large and sparse semiconductor quantum dots emitting at telecommunications wavelengths is proposed. By designing and fabricating such a cavity, we demonstrate a broadband Purcell effect with spontaneous emission enhancement over a broad spectral range of Δλ≃20 nm with a 3.9-fold maximum enhancement, as well as inhibition over Δλ≃100 nm around 1.3 μm. The broadband feature relaxes the constraint on spectral matching between the dot emission and the cavity mode, favourable for implementing efficient non-classical light sources or nanoscale lasers.
Ferromagnetism and ferroelectricity in epitaxial BiMnO3 ultra-thin films
Authors: De Luca G. M. , Preziosi D. , Chiarella F. , Di Capua R. , Gariglio S. , Lettieri S. , Salluzzo M.
Published: August 2013

We studied the ferroelectric and ferromagnetic properties of compressive strained and unstrained BiMnO3 thin films grown by rf-magnetron sputtering. BiMnO3 samples exhibit a two-dimensional cube-on-cube growth mode and a pseudo-cubic structure up to a thickness of 15 nm and of 25 nm when deposited on (001) SrTiO3 and (110) DyScO3, respectively. Above these thicknesses, we observe a switching to a three-dimensional island growth mode and a simultaneous structural change to a (00l) oriented monoclinic unit cell. While ferromagnetism is observed below a TC ≈ 100 K for all samples, signatures of room temperature ferroelectricity were found only in the pseudo-cubic ultra-thin films, indicating a correlation between electronic and structural orders.
Improvement of SiO2/4H-SiC interface properties by electron cyclotron resonance microwave nitrogen-hydrogen mixed plasma post-oxidation annealing
Authors: Zhu Qiaozhi , Qin Fuwen , Li Wenbo , Wang Dejun
Published: August 2013

We proposed an electron cyclotron resonance microwave nitrogen-hydrogen mixed plasma post-oxidation annealing process for SiO2/4H-SiC interface and investigated its effect on the electrical properties of the interface. The results indicate that this process could significantly reduce the density of interface traps (Dit) without degrading the oxide insulating properties. The best result is achieved for the 10-min annealed sample. The N and H, which are only concentrated at the SiO2/SiC interface, both play roles in reducing the Dit. N is more effective in passivating the shallow interface traps, while H is more effective in passivating the deep interface traps.