bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal characterisation of dielectric barrier discharge plasma actuation driven by radio frequency voltage at low pressure
Authors: Zhen Yang , Huimin Song , Weilong Wang , Min Jia , Di Jin
Published: February 2018

In this study, the thermal characterisation of dielectric barrier discharge plasma actuation driven by radio frequency (RF) voltage waveform at low pressure is studied. The RF discharge images and voltage–current waveforms are quite different under 3 and 40 kPa. The thermographic method has been proposed for the spatial–temporal temperature field on the actuator surface. At 3 kPa, the high‐temperature region is mainly concentrated on the surface of the high‐voltage electrode. Along the spanwise direction, the surface temperature gradually increases until it reaches the maximum at the edge of the electrode and then decreases. Similarly, in the chordwise direction, there also exists the maximum value on the surface of the electrode. After discharge starts, the surface temperature rises rapidly, and subsequently, the increasing slope of temperature curves gradually decreases until thermal equilibrium has been reached at about 100 s. The effects of the pressure, duty cycle, and operating power on the thermal characterisation are also investigated experimentally. At low pressure, the discharge mode is diffuse glow discharge, and the high‐temperature region covers the whole electrode. As the pressure increases the surface temperature ascends non‐linearly, while the surface temperature is linearly dependent on the duty cycle and operating power.
Measurement of dielectric response of transformer moisture content
Authors: Zhang Mingze , Liu Ji , Qi Pengshuai , Chen Qingguo , Liao Lilin , Chen Xin , Yin Menghan
Published: February 2018

Over a transformer's operational lifetime, the moisture content of its insulation pressboard increases because of the ageing of its internal insulation. Thus, this moisture content becomes an important index for judging the ageing of this insulation. In this study, to analyse the moisture content of a transformer's insulation pressboard using the dielectric response insulation technique, the XY‐equivalent model analysis method for classical transformers is combined with a dielectric‐constant algorithm for mixed media. In addition, a new method for calculating the moisture content of a pressboard is obtained via cyclic iterative comparison calculations based on the dielectric response translation formula, the temperature, and the material activation energy. The XY‐equivalent models of transformers with various proportions are derived under laboratory conditions. The moisture contents of the transformers’ insulating pressboards are obtained under the corresponding dielectric loss factor curves by using the proposed moisture content calculation method, which provides a result that is within 4.83% of that provided by the IDAX‐300 moisture content analysis algorithm, thus demonstrating its validity.
Facile Access to 3-Unsubstituted Tetrahydroisoquinolonic Acids via the Castagnoli–Cushman Reaction
Authors: Guranova Natalia , Dar’in Dmitry , Krasavin Mikhail
Published: February 2018

Hitherto undescribed 3-unsubstituted tetrahydroisoquinolonic acids (isolated as their respective methyl esters) were accessed for the first time by the uncatalyzed, thermally promoted Castagnoli–Cushman reaction (CCR) of homophthalic anhydride (HPA) and a series of 1,3,5-triazinanes. The moderate yields observed in some cases are most likely associated with a persistent impurity also formed in these reactions. The new scaffold is expected to find novel medicinal utility (compared to the traditional CCR adducts) because it lacks a substituent at the 3-position.
Intrauterine Herpes Simplex Virus Infection Presenting as a Zosteriform Eruption in a Newborn
Authors: Drumm Caitlin , Caufield Maura , DeKlotz Cynthia , Pasieka Helena , Abubakar Kabir
Published: February 2018

There is significant morbidity and mortality associated with the transmission of herpes simplex virus (HSV) from pregnant women to their fetus or newborn. Although most commonly transmitted in the peripartum period, in rare cases HSV can lead to intrauterine infection. Cutaneous lesions are the most common manifestation of intrauterine HSV, and have a wide spectrum of presentation. We present a rare case of intrauterine HSV-2 infection presenting with a zosteriform eruption mimicking congenital varicella syndrome in a newborn.
Epidemiologische Aspekte zum säkularen Trend bei Übergewicht und Adipositas bei Kindern und Jugendlichen
Authors: Beger C. , Spielau U. , Pfäffle R. , Körner A. , Kieß W. , Gausche R.
Published: February 2018

Die Datensammlung des Kinderärztenetzwerks CrescNet ermöglicht es, langfristige Veränderungen in der Entwicklung des Body Mass Index (BMI) bei Kindern und Jugendlichen nachzuweisen. Der BMI von Kindern und Jugendlichen liegt 2006 und 2016 deutlich erhöht gegenüber den Vergleichsdaten aus 1995. Für jüngere Kinder kann zwischen 2006 und 2016 eine leichte Abnahme nachgewiesen werden. Für ältere Kinder und Jugendliche besteht nach wie vor ein großer Handlungsbedarf in der Prävention von Übergewicht und in der Therapie von Adipositas. Verhältnisbezogene Präventionsansätze sollten favorisiert werden und mit Hilfe eines Monitorings von BMI in ihrer Wirksamkeit überprüft werden.
Erfolgreiche Teilnahme an einem interdisziplinären Interventionsprogramm für übergewichtige Kinder
Authors: Roschatt I.S. , Kapitzke K. , Sadeghian E. , Ziegler C. , Bokelmann A. , Galuschka L. , Guntermann K. , Danne T. , Kordonouri O.
Published: February 2018

Es gibt nur wenige Analysen, ob bei übergewichtigen Kindern durch Gewichtsreduktion auch der metabolische Stoffwechsel beeinflusst wird. In dieser Studie wurde die Entwicklung metabolischer Parameter vor und nach der einjährigen Teilnahme an einem interdisziplinären Schulungsprogramm (KICK = Kindergewicht intensiv Coaching im Kinderkrankenhaus) untersucht.

373 Kinder (47,2 % Knaben) mit Übergewicht und Adipositas (BMI >90. Perzentile; BMI-SDS 2,43 ± 0,43, MW ± SD) starteten im Alter von 11,9 ± 2,3 Jahren das KICK-Programm. Metabolische (Gesamt-, HDL- und LDL-Cholesterin, Triglyzeride sowie Nüchternglukose und HbA1c) und somatometrische Parameter sowie der Blutdruck wurden prospektiv zum Beginn und nach einer Follow-up (FU)-Zeit von 1,4 ± 0,4 Jahren erhoben.

Beim FU erreichten die Patienten eine Abnahme des BMI-SDS von 0,78 ± 0,41 (P <0,001). Davon hatten 60 Patienten (46,7 % Jungen) eine signifikante (BMI-SDSDelta ≤-0,5), 96 (42,7 % Jungen) eine moderate (BMI-SDS-Delta ≤-0,2 aber >-0.5) Gewichtsreduktion, 167 (50,9 % Jungen) konnten ihr Gewicht halten (BMI-SDS-Delta >-0,2 und <0,2) und 50 Kinder (44,0 % Jungen) hatten eine Gewichtszunahme (BMI-SDS-Delta ≥0,2). Obwohl wir in der Gesamtgruppe einen metabolisch günstigen Verlauf für alle Lipidparameter (alle P <0,001) und HbA1c (P = 0,021) fanden, waren diese Differenzen insbesondere in den Gruppen der Kinder mit Gewichtsabnahme am ausgeprägtesten. Der HbA1c veränderte sich signifikant in der Gesamtgruppe im Vergleich zum Ausgangswert: HbA1c 5,2 ± 0,7 % vs. 5,3 ± 0,3 % (P <0,05); der nüchterne Glukosewert blieb hingegen unverändert (83,7 ± 7,1 mg/dl vs. 83,5 ± 6,8 mg/ dl, P = 0,693).

Kinder mit einer Gewichtsabnahme im Rahmen eines standardisierten Interventionsprogramms haben eine signifikante Verbesserung der atherogen wirkenden metabolischen Parameter. Dies bestätigt unsere Vermutung, dass bereits bei einer geringen Gewichtsabnahme auch das Risiko von Komorbiditäten sinkt.
Zytostatika-freie Regime: Alternative zur Immunchemotherapie
Authors: Arnheim Katharina
Published: February 2018

Bei der chronischen lymphatischen Leukämie (CLL) haben sich Kombinations-Chemotherapien als effektiv erwiesen. Die Wirksamkeit konnte in der Folge durch Addition monoklonaler Antikörper noch gesteigert werden. Mittlerweile wurden neue Substanzen entwickelt, die innovative Kombinationsoptionen eröffnen und eine verbesserte Eradikation der minimalen Resterkrankung (MRD) erlauben. Eine Rückschau auf den ASH 2017.
Zielgenaue Bestrahlung schützt Kognition und Hormonachse
Authors: Krome Susanne
Published: February 2018

Im Vergleich zur konventionellen Bestrahlung ermöglicht die stereotaktische konformale Radiatio eine exaktere Positionierung und Zielpunktdefinition. Damit soll eine bessere Tumorkontrolle und insbesondere eine gesteigerte Schonung des Umgebungsgewebes erreicht werden. In der prospektiven Langzeitstudie profitierten junge Patienten mit einem niedrig malignen Gehirntumor von der SCRT.
Musikalische Inaktivität – ein Risikofaktor? Vorstellung eines kurzen Fragebogens zur Erfassung der musikalischen Aktivität (MusA)
Authors: Fernholz Isabel , Menzel Juliane , Jabusch Hans-Christian , Gembris Heiner , Fischer Felix , Kendel Friederike , Kreutz Gunter , Schmidt Alexander , Willich Stefan N. , Weikert Cornelia
Published: February 2018

Hintergrund Zusammenhänge zwischen musikalischer Aktivität und dem Auftreten von Erkrankungen sind bisher nur in wenigen Studien untersucht, obgleich es viele Hinweise gibt, dass musikalische Aktivität einen Einfluss auf physiologische, pathophysiologische, psychische und kognitive Prozesse hat. Eine Ursache für die geringe Anzahl größerer Studien könnte das Fehlen eines geeigneten Erhebungsinstrumentes sein.

Ziel Ziel der vorliegenden Arbeit ist es, einen Überblick über Erhebungsinstrumente zur Erfassung von Musikalität und musikalischer Aktivität zu geben. Ein Schwerpunkt liegt dabei in der Vorstellung eines neu entwickelten Fragebogens (MusA), der die musikalische Aktivität (aktives Musizieren und Musikrezeption) erfasst und derzeit bereits in der NAKO Gesundheitsstudie eingesetzt wird.

Methode Mittels Literaturrecherche wurden Fragebögen identifiziert, die Musikalität und/ oder musikalische Aktivität erfassen. Von einer Expertenrunde wurde ein neuer deutschsprachiger Fragebogen entwickelt und in einer kleinen Studie hinsichtlich seiner Reliabilität getestet (n=121, Männer und Frauen im Alter von 18 bis 70 Jahren).

Ergebnisse Bei der Literaturrecherche wurden 3 Fragebögen (Gold-MSI, MUSE, MEQ) identifiziert, die sich mit Aspekten der Musikalität und musikalischen Aktivität mit jeweils unterschiedlicher Schwerpunktsetzung befassen. Alle 3 Instrumente sind als umfangreiche psychometrische Skalen zu bewerten, die sich insbesondere der Musikalität widmen. Bisher steht nur der Gold-MSI in einer deutschen Übersetzung zur Verfügung. Keiner der 3 bestehenden Fragebögen erfasst die musikalische Aktivität differenziert. Der neu entwickelte, kurze MusA-Fragebogen, bestehend aus 9 Fragen mit einer maximalen Ausfülldauer von 3 bis 5 Min, schließt diese Lücke.

Zusammenfassung Es stehen nur wenige Fragebögen zur Erfassung von Musikalität und musikalischer Aktivität mit unterschiedlicher Schwerpunktsetzung zur Verfügung. Der neu entwickelte deutschsprachige MusA dient der differenzierten Erfassung von musikalischer Aktivität und soll eingesetzt werden, um in größeren populationsbasierten aber auch klinischen Studien wie z. B. der NAKO Gesundheitsstudie aktives Musizieren und Musikhören als eigenständige Faktoren im Zusammenhang mit Prävention und Therapie chronischer Erkrankungen untersuchen zu können.
Fabrication of phonon-based metamaterial structures using focused ion beam patterning
Authors: Bassim Nabil D. , Giles Alexander J. , Ocola Leonidas E. , Caldwell Joshua D.
Published: February 2018

The focused ion beam (FIB) is a powerful tool for rapid prototyping and machining of functional nanodevices. It is employed regularly to fabricate test metamaterial structures but, to date, has been unsuccessful in fabricating metamaterial structures with features at the nanoscale that rely on surface phonons as opposed to surface plasmons because of the crystalline damage that occurs with the collision cascade associated with ion sputtering. In this study, we employ a simple technique of protecting the crystalline substrate in single-crystal 4H-SiC to design surface phonon polariton-based optical resonance structures. By coating the material surface with a thin film of chromium, we have placed a material of high sputter resistance on the surface, which essentially absorbs the energy in the beam tails. When the beam ultimately punches through the Cr film, the hard walls in the film have the effect of channeling the beam to create smooth sidewalls. This demonstration opens the possibility of further rapid-prototyping of metamaterials using FIB.
Strain effect on the photoluminescence property of gold nanoclusters
Authors: Saravanan K. , David C. , Jayalakshmi G. , Panigrahi B. K. , Avasthi D. K.
Published: February 2018

Herein, we report the temperature-dependent photoluminescence (PL) properties of Au nanoclusters (NCs) embedded in a Si matrix. Gold NCs have been synthesized in Si by a multistep procedure that involves ion implantation and gold decoration by drive in annealing. Transmission electron microscopic studies reveal profuse nucleation of Au NCs, with mean sizes of ∼8 nm in the near-surface region. PL measurements in the range of 2 eV to 3.65 eV were carried out in the temperature range of 5 K to 300 K. The Au NCs exhibit PL emissions at 3 eV and 2.5 eV; these are attributed to the recombination of sp-band electrons with the holes of a deep lying d-band below the Fermi level in the vicinity of the L symmetry point of the Brillouin zone and the recombination of sp band electrons with the holes of the first d band below the Fermi level in the vicinity of the X symmetry point of the Brillouin zone, respectively. Temperature-dependent PL measurements show that the PL intensity of Au NCs initially decreases with the increase of temperature up to 50 K, and, thereafter, the intensity starts to increase and reaches a maximum at 150 K. A further increase in temperature causes the intensity to decrease. However, the PL intensity of Au NCs embedded in a sapphire matrix monotonically decreases with the increase of temperature. The present work discusses the plausible mechanism behind this unusual PL behaviour by invoking the role of strain at the NC-matrix interface.
Controlling chaotic spin-motion entanglement of ultracold atoms via spin-orbit coupling
Authors: Kong Chao , Chen Hao , Li Chunlai , Hai Wenhua
Published: February 2018

We study the spatially chaoticity-dependent spin-motion entanglement of a spin-orbit (SO) coupled Bose-Einstein condensate with a source of ultracold atoms held in an optical superlattice. In the case of phase synchronization, we analytically demonstrate that (a) the SO coupling (SOC) leads to the generation of spin-motion entanglement; (b) the area of the high-chaoticity parameter region inversely relates to the SOC strength which renormalizes the chemical potential; and (c) the high-chaoticity is associated with the lower chemical potential and the larger ratio of the short-lattice depth to the longer-lattice depth. Then, we numerically generate the Poincaré sections to pinpoint that the chaos probability is enhanced with the decrease in the SOC strength and/or the spin-dependent current components. The existence of chaos is confirmed by computing the corresponding largest Lyapunov exponents. For an appropriate lattice depth ratio, the complete stop of one of (or both) the current components is related to the full chaoticity. The results mean that the weak SOC and/or the small current components can enhance the chaoticity. Based on the insensitivity of chaos probability to initial conditions, we propose a feasible scheme to manipulate the ensemble of chaotic spin-motion entangled states, which may be useful in coherent atom optics with chaotic atom transport.
Simulation study of ballistic spin-MOSFET devices with ferromagnetic channels based on some Heusler and oxide compounds
Authors: Graziosi Patrizio , Neophytou Neophytos
Published: February 2018

Newly emerged materials from the family of Heuslers and complex oxides exhibit finite bandgaps and ferromagnetic behavior with Curie temperatures much higher than even room temperature. In this work, using the semiclassical top-of-the-barrier FET model, we explore the operation of a spin-MOSFET that utilizes such ferromagnetic semiconductors as channel materials, in addition to ferromagnetic source/drain contacts. Such a device could retain the spin polarization of injected electrons in the channel, the loss of which limits the operation of traditional spin transistors with non-ferromagnetic channels. We examine the operation of four material systems that are currently considered some of the most prominent known ferromagnetic semiconductors: three Heusler-type alloys (Mn2CoAl, CrVZrAl, and CoVZrAl) and one from the oxide family (NiFe2O4). We describe their band structures by using data from DFT (Density Functional Theory) calculations. We investigate under which conditions high spin polarization and significant ION/IOFF ratio, two essential requirements for the spin-MOSFET operation, are both achieved. We show that these particular Heusler channels, in their bulk form, do not have adequate bandgap to provide high ION/IOFF ratios and have small magnetoconductance compared to state-of-the-art devices. However, with confinement into ultra-narrow sizes down to a few nanometers, and by engineering their spin dependent contact resistances, they could prove promising channel materials for the realization of spin-MOSFET transistor devices that offer combined logic and memory functionalities. Although the main compounds of interest in this paper are Mn2CoAl, CrVZrAl, CoVZrAl, and NiFe2O4 alone, we expect that the insight we provide is relevant to other classes of such materials as well.
Thermal annealing and single–domain preparation in tetragonal Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 crystal for electro–optic and non–linear optical applications
Authors: Zhao Ye , Wang Sanhong , Fu Xiaotian , Zhuang Yongyong , Yang Rui , Yang Zhi , Li Zhenrong , Xu Zhuo , Wei Xiaoyong
Published: February 2018

The relaxor–PbTiO3 single crystal has attracted extensive attention in ultrasound transducers, sensors, actuators, and optoelectronics devices due to its excellent piezoelectric response and electro–optic properties. Preparation of a single–domain crystal as a critical process for application in electro–optic and non–linear optical devices suffers from serious and inevitable cracking. Therefore, a pre-poling thermal annealing process was suggested to release residual stress from crystal growth and the ferroelectric–paraelectric phase transition, which significantly reduced the chance of cracking. The effect of thermal annealing on dielectric properties, strain behavior, and domain structure were investigated. As a result, a significant increase of the dielectric constant near room temperature was obtained after annealing, which is close to the dielectric constant of the a-oriented domain. The annealed single crystal showed a lower and sharper strain peak at the coercive electric field compared with the unannealed sample, and the 90° domain walls completely vanished, which was verified by optical microscopy. The crack–free single–domain crystal showed excellent optical quality, with high transmittance of approximately 70% in the visible and near–infrared regions, which indicates that this crystal is a promising candidate for applications in electro–optic and non–linear optical devices.
Understanding the adhesion and optical properties of eutectic metal alloys for solution-processed electronics
Authors: Kumar Prashant , Aggarwal Shantanu , Narayana Chandrabhas , Narayan K. S.
Published: February 2018

The role of indium in controlling the adhesion and the optical properties of fusible, low- melting alloys is highlighted in this work. The optical activity of indium-alloy/polymer interface is probed using surface-enhanced Raman spectroscopy, which shows a large increase in polymer Raman modes intensity. Signatures of plasmon and chemically enhanced Raman are visible for more than one polymer. Improvement in adhesion is also reflected in their ability to coat conformally onto the polymer surface resulting in a suitable interface for electrical transport. The electrical characteristics of alloy electrodes, which are printed in ambient conditions, are superior when compared to the thermally evaporated aluminum cathodes. Raman and responsivity measurements indicate that indium (In) forms metal/organic hybrid charge-transfer states at the alloy/polymer interface and assumes a decisive role in controlling the mechanical, optical, and electrical properties of these electrodes. Our studies suggest that the indium present in small quantities (∼5 wt. %) can significantly improve the overall performance of the low-temperature printable eutectic alloy electrodes.
Single-shot dual-wavelength in-line and off-axis hybrid digital holography
Authors: Wang Fengpeng , Wang Dayong , Rong Lu , Wang Yunxin , Zhao Jie
Published: February 2018

We propose an in-line and off-axis hybrid holographic real-time imaging technique. The in-line and off-axis digital holograms are generated simultaneously by two lasers with different wavelengths, and they are recorded using a color camera with a single shot. The reconstruction is carried using an iterative algorithm in which the initial input is designed to include the intensity of the in-line hologram and the approximate phase distributions obtained from the off-axis hologram. In this way, the complex field in the object plane and the output by the iterative procedure can produce higher quality amplitude and phase images compared to traditional iterative phase retrieval. The performance of the technique has been demonstrated by acquiring the amplitude and phase images of a green lacewing's wing and a living moon jellyfish.
Tuning magnetic ordering in a dipolar square-kite tessellation
Authors: Petersen Charlotte F. , Farhan Alan , Dhuey Scott , Chen Zuhuang , Alava Mikko J. , Scholl Andreas , van Dijken Sebastiaan
Published: February 2018

The potential application of artificial spin ice in magnetic nanodevices provides a strong drive to investigate different lattice geometries. Here, we combine components of a recently investigated artificial spin ratchet with components of the prototypical square lattice to form a geometrically frustrated artificial spin ice system where Ising-type nanomagnets are arranged onto a two-dimensional square-kite lattice. Using synchrotron-based photoemission electron microscopy, we explore moment configurations achieved in this lattice geometry. Following thermal annealing, we image how a variation of the relevant lattice parameter affects magnetic ordering in four-island squares and four-island vertices during cooling through the Blocking temperature. Depending on lattice spacing, both nearly uniform and disordered spin configurations are accessible in our samples. We show that the relative energies of the building blocks of the system, which are typically used to classify lattice configurations, are not predictive of the low energy states adopted by the experimental system. To understand magnetic ordering in the square-kite lattice, longer range interactions must be considered.
Conservative regularization of compressible dissipationless two-fluid plasmas
Authors: Krishnaswami Govind S. , Sachdev Sonakshi , Thyagaraja A.
Published: February 2018

This paper extends our earlier approach [cf. A. Thyaharaja, Phys. Plasmas 17, 032503 (2010) and Krishnaswami et al., Phys. Plasmas 23, 022308 (2016)] to obtaining à priori bounds on enstrophy in neutral fluids and ideal magnetohydrodynamics. This results in a far-reaching local, three-dimensional, non-linear, dispersive generalization of a KdV-type regularization to compressible/incompressible dissipationless 2-fluid plasmas and models derived therefrom (quasi-neutral, Hall, and ideal MHD). It involves the introduction of vortical and magnetic “twirl” terms λl2(wl+(ql/ml)B)×(∇×wl) in the ion/electron velocity equations (l=i,e) where wl are vorticities. The cut-off lengths λl and number densities nl must satisfy λl2nl=Cl, where Cl are constants. A novel feature is that the “flow” current ∑lqlnlvl in Ampère's law is augmented by a solenoidal “twirl” current ∑l∇×∇×λl2jflow,l. The resulting equations imply conserved linear and angular momenta and a positive definite swirl energy density E* which includes an enstrophic contribution ∑l(1/2)λl2ρlwl2. It is shown that the equations admit a Hamiltonian-Poisson bracket formulation. Furthermore, singularities in ∇×B are conservatively regularized by adding (λB2/2μ0)(∇×B)2 to E*. Finally, it is proved that among regularizations that admit a Hamiltonian formulation and preserve the continuity equations along with the symmetries of the ideal model, the twirl term is unique and minimal in non-linearity and space derivatives of velocities.
Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells
Authors: Yan Yaming , Song Linze , Shi Qiang
Published: February 2018

By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings.
Relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn: Consistent parameterization and prediction of Seebeck coefficients
Authors: Shi Guangsha , Kioupakis Emmanouil
Published: February 2018

We apply density functional and many-body perturbation theory calculations to consistently determine and parameterize the relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn, and predict the Seebeck coefficient as a function of doping and temperature. The quasiparticle band gaps, including spin-orbit coupling effects, are determined to be 0.728 eV, 0.555 eV, and 0.142 eV for Mg2Si, Mg2Ge, and Mg2Sn, respectively. The inclusion of the semicore electrons of Mg, Ge, and Sn in the valence is found to be important for the accurate determination of the band gaps of Mg2Ge and Mg2Sn. We also developed a Luttinger-Kohn Hamiltonian and determined a set of band parameters to model the near-edge relativistic quasiparticle band structure consistently for all three compounds that can be applied for thermoelectric device simulations. Our calculated values for the Seebeck coefficient of all three compounds are in good agreement with the available experimental data for a broad range of temperatures and carrier concentrations. Our results indicate that quasiparticle corrections are necessary for the accurate determination of Seebeck coefficients at high temperatures at which bipolar transport becomes important.
Stresses in non-equilibrium fluids: Exact formulation and coarse-grained theory
Authors: Krüger Matthias , Solon Alexandre , Démery Vincent , Rohwer Christian M. , Dean David S.
Published: February 2018

Starting from the stochastic equation for the density operator, we formulate the exact (instantaneous) stress tensor for interacting Brownian particles and show that its average value agrees with expressions derived previously. We analyze the relation between the stress tensor and forces due to external potentials and observe that, out of equilibrium, particle currents give rise to extra forces. Next, we derive the stress tensor for a Landau-Ginzburg theory in generic, non-equilibrium situations, finding an expression analogous to that of the exact microscopic stress tensor, and discuss the computation of out-of-equilibrium (classical) Casimir forces. Subsequently, we give a general form for the stress tensor which is valid for a large variety of energy functionals and which reproduces the two mentioned cases. We then use these relations to study the spatio-temporal correlations of the stress tensor in a Brownian fluid, which we compute to leading order in the interaction potential strength. We observe that, after integration over time, the spatial correlations generally decay as power laws in space. These are expected to be of importance for driven confined systems. We also show that divergence-free parts of the stress tensor do not contribute to the Green-Kubo relation for the viscosity.
Multivalued classical mechanics arising from singularity loops in complex time
Authors: Koch Werner , Tannor David J.
Published: February 2018

Complex-valued classical trajectories in complex time encounter singular times at which the momentum diverges. A closed time contour around such a singular time may result in final values for q and p that differ from their initial values. In this work, we develop a calculus for determining the exponent and prefactor of the asymptotic time dependence of p from the singularities of the potential as the singularity time is approached. We identify this exponent with the number of singularity loops giving distinct solutions to Hamilton’s equations of motion. The theory is illustrated for the Eckart, Coulomb, Morse, and quartic potentials. Collectively, these potentials illustrate a wide variety of situations: poles and essential singularities at finite and infinite coordinate values. We demonstrate quantitative agreement between analytical and numerical exponents and prefactors, as well as the connection between the exponent and the time circuit count. This work provides the theoretical underpinnings for the choice of time contours described in the studies of Doll et al. [J. Chem. Phys. 58(4), 1343–1351 (1973)] and Petersen and Kay [J. Chem. Phys. 141(5), 054114 (2014)]. It also has implications for wavepacket reconstruction from complex classical trajectories when multiple branches of trajectories are involved.
First-principles simulations of binding energies of alloying elements to the ferrite-austenite interface in iron
Authors: Jin Hao , Elfimov Ilya , Militzer Matthias
Published: February 2018

The kinetics of the ferrite-austenite (bcc-fcc) phase transformation in steels are markedly affected by substitutional alloying elements. However, the detailed mechanisms of their interaction with the bcc-fcc interfaces are not fully understood. In this study, the effects of common alloying elements (e.g., Nb, Mo, Mn, Si, Cr, and Ni) on the structure, segregation, and magnetic properties of bcc-fcc interfaces in Fe are systematically investigated using spin-polarized Density Functional calculations within a generalized gradient approximation to the exchange correlation potential and a super cell approach with a Kurdjumov-Sachs orientation relationship between bcc and fcc. The calculation results are in semi-quantitative agreement with the experimental results, i.e., Nb has the largest binding energy to the bcc-fcc interface in Fe followed by Mo.
Analysis of diamond pseudo-vertical Schottky barrier diode through patterning tungsten growth method
Authors: Zhao Dan , Liu Zhangcheng , Zhang Xiaofan , Zhang Minghui , Wang Yanfeng , Shao Guoqing , Zhang Jingwen , Fan Shuwei , Wang Wei , Wang Hongxing
Published: February 2018

In this study, diamond pseudo-vertical architecture Schottky barrier diodes (PVSBDs) through the patterning tungsten growth method have been investigated. The forward current density is 16 A/cm2 at 5 V, and a rectification ratio is more than 5 orders of magnitude at ±5 V for diamond PVSBD. The reverse breakdown voltage is 640 V, and the corresponding electrical field is 4.57 MV/cm. These results are obtained by patterning tungsten (W) on the diamond surface as a blocking layer and growing a diamond epitaxial layer on the uncovered zone. A W/diamond ohmic contact was formed during the diamond epitaxial layer growth process. An aluminum film was used as a Schottky contact. Overall, the results illustrate that W patterned growth to fabricate PVSBD is efficient.
Nonlinear structure formation in ion-temperature-gradient driven drift waves in pair-ion plasma with nonthermal electron distribution
Authors: Razzaq Javaria , Haque Q. , Khan Majid , Bhatti Adnan Mehmood , Kamran M. , Mirza Arshad M.
Published: February 2018

Nonlinear structure formation in ion-temperature-gradient (ITG) driven waves is investigated in pair-ion plasma comprising ions and nonthermal electrons (kappa, Cairns). By using the transport equations of the Braginskii model, a new set of nonlinear equations are derived. A linear dispersion relation is obtained and discussed analytically as well as numerically. It is shown that the nonthermal population of electrons affects both the linear and nonlinear characteristics of the ITG mode in pair-ion plasma. This work will be useful in tokamaks and stellarators where non-Maxwellian population of electrons may exist due to resonant frequency heating, electron cyclotron heating, runaway electrons, etc.
Control of magnetic vortex polarity by the phase difference between voltage signals
Authors: Cui Huanqing , Cai Li , Yang Xiaokuo , Wang Sen , Zhang Mingliang , Li Cheng , Feng Chaowen
Published: February 2018

Using micromagnetic simulations, we investigate the voltage control of magnetic vortex polarity based on a designed multiferroic heterostructure that contains two separate piezoelectric films beneath a magnetostrictive nanodisk. The results show that controllable switching of vortex polarity can be achieved by proper modulation of the phase difference between two sinusoidal voltage pulses V1 and V2, which are applied to the two separate piezoelectric films, respectively. The frequencies of V1 and V2 are set at the gyrotropic eigenfrequency fG of the nanodisk, and the vortex polarity switching is completed via the nucleation-annihilation process of the vortex-antivortex pair. Our findings provide an additional effective means for ultralow power switching of the magnetic vortex, which lays the foundation for voltage-controlled vortex random access memory.
Analysis of localized surface plasmon resonances in gold nanoparticles surrounded by copper oxides
Authors: Stamatelatos A. , Sousanis A. , Chronis A. G. , Sigalas M. M. , Grammatikopoulos S. , Poulopoulos P.
Published: February 2018

Au-doped Cu thin films are produced by co-deposition of Au and Cu via radiofrequency magnetron sputtering in a vacuum chamber with a base pressure of 1 × 10−7 mbar. After post annealing in a furnace with air, one may obtain either Au-Cu2O or Au-CuO nanocomposite thin films. The presence of Au does not have any considerable influence on the position of the optical band gap of the oxides. Only the Au-CuO system shows well-formed localized surface plasmonic resonances with Gaussian shape. We study systematically the plasmonic behavior of the nanocomposites as a function of the gold concentration, annealing time, and film thickness. The intensity of the resonances, their position, and width are intensely affected by all these parameters. The experimental results are compared with respect to rigorous theoretical calculations. The similarities and differences between experiment and theory are discussed.
Communication: Simple liquids’ high-density viscosity
Authors: Costigliola Lorenzo , Pedersen Ulf R. , Heyes David M. , Schrøder Thomas B. , Dyre Jeppe C.
Published: February 2018

This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.
A new ab initio potential energy surface for the NH–He complex
Authors: Ramachandran R. , Kłos J. , Lique F.
Published: February 2018

We present a new three-dimensional potential energy surface (PES) for the NH(X3Σ−)–He van der Waals system, which explicitly takes into account the NH vibrational motion. The NH–He PES was obtained using the open-shell single- and double-excitation coupled cluster approach with non-iterative perturbational treatment of triple excitations. The augmented correlation-consistent aug-cc-pVXZ (X = Q, 5, 6) basis sets were employed, and the energies obtained were then extrapolated to the complete basis set limit. Using this new PES, we have studied the spectroscopy of the NH–He complex and we have determined a new rotational constant that agrees well with the available experimental data. Collisional excitation of NH(X3Σ−) by He was also studied at the close-coupling level. Calculations of the collisional excitation cross sections of the fine-structure levels of NH by He were performed for energies up to 3500 cm−1, which yield, after thermal average, rate coefficients up to 350 K. The calculated rate coefficients are compared with available experimental measurements at room temperature, and a reasonably good agreement is found between experimental and theoretical data.
Human Ska complex and Ndc80 complex interact to form a load-bearing assembly that strengthens kinetochore–microtubule attachments
Authors: Helgeson Luke A. , Zelter Alex , Riffle Michael , MacCoss Michael J. , Asbury Charles L. , Davis Trisha N.
Published: February 2018

Significance

Microtubules are dynamic, tube-like structures that drive the segregation of duplicated chromosomes during cell division. The Ska complex is part of a molecular machine that forms force-bearing connections between chromosomes and microtubule ends. Depletion of the Ska complex destabilizes these connections and disrupts cell division. The Ska complex binds microtubules, but it is unknown whether it directly holds force at microtubules or indirectly stabilizes the connections. Here, we show that the Ska complex makes a direct force-bearing linkage with microtubule ends and assembles with another microtubule binding component, the Ndc80 complex, to strengthen its ability to withstand force. Our results suggest that the Ska and Ndc80 complexes work together to maintain the connections between chromosomes and microtubule ends.
Structural basis of transcriptional stalling and bypass of abasic DNA lesion by RNA polymerase II
Authors: Wang Wei , Walmacq Celine , Chong Jenny , Kashlev Mikhail , Wang Dong
Published: February 2018

Significance

Abasic DNA lesions are one of the most abundant types of DNA lesions and are frequent byproducts of normal cellular metabolism, and they represent intermediates in the base excision repair pathway. These DNA lesions can lead to DNA mutations and transcription errors and block replication and transcription. The molecular basis for RNA polymerase II (Pol II) stalling and bypass of abasic lesion remains elusive due to a lack of atomic structural information. Here we reported the structural snapshots of Pol II stalling and bypass of abasic DNA lesion in a step-wise manner and elucidated how bypass of the lesion leads to the errors in RNA transcripts. These results provide important mechanistic insight into understanding the biological consequences of these abundant mutagenic DNA lesions.
Effect of surface relief on solid phase joining of heat-resistant nickel superalloys
Authors: Galieva E. V. , Lutfullin R. Ya. , Akhunova A. Kh. , Valitov V. A. , Dmitriev S. V.
Published: February 2018

Pressure welding (PW) is an advanced method for obtaining solid phase joints (SPJs). Using physical and finite element modelling (FEM) it is shown that PW under superplasticity conditions provides SPJs between dissimilar cast single-crystal intermetallic and deformed polycrystalline heat-resistant Ni-based superalloys. Special attention is paid to exclude the stagnant zones in the solid phase joining region using surface relief. The results of physical modelling and FEM are in qualitative agreement. It is revealed that the surface relief can decrease the stagnant zone and increase localisation of deformation in the joining region, which helps to improve the joining quality. A monotonous change in microhardness in the joint zone is shown.
Reconstitution and functional characterization of ion channels from nanodiscs in lipid bilayers
Authors: Winterstein Laura-Marie , Kukovetz Kerri , Rauh Oliver , Turman Daniel L. , Braun Christian , Moroni Anna , Schroeder Indra , Thiel Gerhard
Published: February 2018

Recent studies have shown that membrane proteins can be efficiently synthesized in vitro before spontaneously inserting into soluble nanoscale lipid bilayers called nanodiscs (NDs). In this paper, we present experimental details that allow a combination of in vitro translation of ion channels into commercially available NDs followed by their direct reconstitution from these nanobilayers into standard bilayer setups for electrophysiological characterization. We present data showing that two model K+ channels, Kcv and KcsA, as well as a recently discovered dual-topology F− channel, Fluc, can be reliably reconstituted from different types of NDs into bilayers without contamination from the in vitro translation cocktail. The functional properties of Kcv and KcsA were characterized electrophysiologically and exhibited sensitivity to the lipid composition of the target DPhPC bilayer, suggesting that the channel proteins were fully exposed to the target membrane and were no longer surrounded by the lipid/protein scaffold. The single-channel properties of the three tested channels are compatible with studies from recordings of the same proteins in other expression systems. Altogether, the data show that synthesis of ion channels into NDs and their subsequent reconstitution into conventional bilayers provide a fast and reliable method for functional analysis of ion channels.
Workplace Identity Construction: An Intersectional-Identity-Cultural Lens
Authors: Booysen Lize A. E.
Published: February 2018

With the development of an integrated cross-disciplinary framework to study workplace identity construction, the current theoretical discussion on workplace identity construction is extended—first, by focusing on intersectionality as theoretical lens and methodology in our thinking about workplace identity, highlighting the significance of an individual’s intersections of social locations in the workplace embedded in socio-historical and political contexts, and second, by focusing on the influence of national culture and societal landscapes as important macro contextual factors, adding a super-group level and a cross-cultural perspective on how individuals navigate their identities at work.

Using an intersectional-identity-cultural conceptualization of workplace identity formation elucidates the personal, social identity, sub-group, group, and super group level of influences on identity formation. It focuses on the interplay between individual, relational, collective, and group identity, and emphasizes social identity as the bridge between personal identity and group identity. It highlights the multiplicity, simultaneity, cross cutting, intersecting, as well as differing prominence and power differences of social identities based on differing contexts. It illustrates the relatively stable yet fluid nature of individual (intra-personal and core) identity as it adapts to the environment, and the constant changing, co-constructed, negotiated, and re-negotiated nature of relational (inter-personal), collective identity (social identity) as it gets produced and re-produced, shaped and reshaped by both internal and external forces, embedded in socio-historical-political workplace contexts.

Understanding the interplay of the micro-level, individual (agency), relational, and collective identity levels (social construction), nested in the meso level structures of domination, and group dynamics in the workplace (control regulation/political) in its macro level societal landscape context (additional control regulation) will help us to understand the cognitive sense-making processes individuals engage in when constructing workplace identities. This understanding can help to create spaces where non-normative individuals can resist, disrupt, withdraw, or refuse to enact the limited accepted identities and can create alternative discourse or identity possibilities.
Political Economy of the Media
Authors: Jin Dal Yong
Published: February 2018

Political economy of the media includes several domains including journalism, broadcasting, advertising, and information and communication technology. A political economy approach analyzes the power relationships between politics, mediation, and economics. First, there is a need to identify the intellectual history of the field, focusing on the establishment and growth of the political economy of media as an academic field. Second is the discussion of the epistemology of the field by emphasizing several major characteristics that differentiate it from other approaches within media and communication research. Third, there needs an understanding of the regulations affecting information and communication technologies (ICTs) and/or the digital media-driven communication environment, especially charting the beginnings of political economy studies of media within the culture industry. In particular, what are the ways political economists develop and use political economy in digital media and the new media milieu driven by platform technologies in the three new areas of digital platforms, big data, and digital labor. These areas are crucial for analysis not only because they are intricately connected, but also because they have become massive, major parts of modern capitalism.
Greece and the European Union
Authors: Blavoukos Spyros
Published: February 2018

Based on negative publicity related to the financial turmoil and the migration crisis one could perhaps classify Greece as a problematic EU partner. This contribution argues that this static approach does not fully describe the complexity of EU-Greece relations. Looking at the historical evolution of this relationship from a more macroscopic point of view it identifies periods of convergence and divergence. It reinstates the limits of the European adjustment pressures in inducing modernization and accounts for the crises episodes by reference to some idiosyncratic features of the domestic sociopolitical contestation. The contribution discusses the valuable lessons learned by the handling of the crises both for Greece and the EU. It stresses that the Greek public disenchantment with the EU that is inexorably linked with the extreme societal burden of the adjustment process is not an isolated phenomenon. Like in many other EU countries, much of the criticism is directed toward the current scope and direction of European integration rather than on the merits and value of the integration venture per se. What is urgently required for the whole European demos is a new “grand bargain” that will provide the necessary vision for the years to come. This will condition the future evolution of the EU-Greece relationship.