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Physics of Fluids : Large amplitude internal solitary waves in a t...

By: Arnaud Goullet and Wooyoung Choi

Description: We study large amplitude internal solitary waves in a two-layer system where each layer has a constant buoyancy frequency (or Brunt–Väisälä frequency). The strongly nonlinear model originally derived by Voronovich [J. Fluid Mech. 474, 85 (2003) ] under the long wave assumption for a density profile discontinuous across the interface is modified for continuous density stratification. For a wide range of depth and buoyancy frequency ratios, the solitary wave s...

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Journal of Applied Physics : Strain relaxation in InAs self-assemb...

By: J. F. Chen, C. H. Yang, Y. H. Wu, L. Chang, and J. Y. Chi

Description: The effect of a high N incorporation in self-assembled InAs quantum dots (QDs) is investigated by analyzing the electronic and structural properties around QD region. Capacitance-voltage profiling and admittance spectroscopy shows that N incorporation into the InAs QD layer leads to drastic carrier depletion in the QD layer and neighboring GaAs layers due to the formation of a deep defect state at 0.34–0.41 eV. The signature of this defect state is similar t...

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The Journal of Chemical Physics : Photodissociation dynamics of me...

By: Shih-Huang Lee

Description: We investigated the photodissociation dynamics of methyl formate-d (CH3OC(O)D) at 193.3 nm in a molecular-beam apparatus using undulator radiation as an ionization source. We measured kinetic-energy distributions, spatial angular anisotropies, and branching ratios of all photofragments. Fractions of energy release into product translation were calculated from the kinetic-energy distributions. Four primary dissociation pathways to asymptotes CH3O( 2E)+DCO( 2A...

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Applied Physics Letters : Growth and magnetic control of twinning ...

By: C. A. Jenkins, R. Ramesh, M. Huth, T. Eichhorn, P. Pörsch et al

Description: Twin structure engineering in sputtered films close to the Heusler stoichiometry Ni2MnGa (001) is used to demonstrate temperature and magnetic control of the phase transformation behavior. A custom heating apparatus integrated with a commercial microscope allows the observation of the austenite-martensite transition in epitaxially clamped films. Intermartensitic twin boundaries on cantilevers released from the epitaxial strain by focused ion beam etching are...

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Physics of Fluids : Water bells created from below

By: Graeme J. Jameson, Claire Jenkins, Eleanor C. Button, and John E. Sader

Description:

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Applied Physics Letters : Determining the optimum pentacene channe...

By: Sung-jin Mun, Jeong-M. Choi, Kwang H. Lee, Kimoon Lee, and Seongil Im

Description: We report that the optimum pentacene channel thickness is dependent on the surface energy state of its dielectric substrate. Pentacene thin-film transistor (TFT) with hydrophobic substrate displays a peak linear mobility at an optimum channel thickness of 50 nm, below or above which the linear mobility decreases. In contrast, the linear mobility of the TFT with hydrophilic substrate monotonically increases until the channel thickness decreases to 15 nm. Acco...

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Physics of Plasmas : Variational derivation of the dispersion rela...

By: C. Nguyen, X. Garbet, and A. I. Smolyakov

Description: In the present paper, we compare two modes with frequencies belonging to the acoustic frequency range: the geodesic acoustic mode (GAM) and the Beta Alfvén eigenmode (BAE). For this, a variational gyrokinetic energy principle coupled to a Fourier sidebands expansion is developed. High order finite Larmor radius and finite orbit width effects are kept. Their impact on the mode structures and on the Alfvén spectrum is calculated and discussed. We show that in ...

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Journal of Applied Physics : Adhesion and interfacial fracture tou...

By: Nima Rahbar, Kurt Wolf, Argjenta Orana, Roy Fennimore, Zong Zong et al

Description: This paper presents the results of a combined experimental and theoretical study of adhesion between hard and soft layers that are relevant to medical devices such as drug-eluting stents and semiconductor applications. Brazil disk specimens were used to measure the interfacial fracture energies between model parylene C and 316L stainless steel over a wide range of mode mixities. The trends in the overall fracture energies are predicted using a combination of...

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Physics of Fluids : Electrokinetic flows over inhomogeneously slip...

By: Todd M. Squires

Description: Recent measurements and theory suggest that some solid/liquid surfaces can exhibit slip, at times to a surprising degree. Proposed mechanisms for slip include both intrinsic molecular slip as well as “effective” slip over complex and multiphase interfaces (i.e., covered with “lubricating” nanobubbles or trapped gas pockets). Electrokinetic flow velocities can be significantly enhanced over slipping surfaces as the high shear rates within the double layer dri...

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Physics of Fluids : Stability of a pair of co-rotating vortices wi...

By: Clément Roy, Nathanaël Schaeffer, Stéphane Le Dizès, and Mark Thompson

Description: The three-dimensional linear temporal stability properties of a flow composed of two corotating q-vortices (also called Batchelor vortices) are predicted by numerical stability analysis. As for the corresponding counter-rotating case, when the axial flow parameter is increased, different instability modes are observed and identified as a combination of resonant Kelvin modes of azimuthal wavenumbers m and m+2 within each vortex. In particular, we show that th...

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Chaos : Community structures and role detection in music networks

By: T. Teitelbaum, P. Balenzuela, P. Cano, and Javier M. Buldú

Description: We analyze the existence of community structures in two different social networks using data obtained from similarity and collaborative features between musical artists. Our analysis reveals some characteristic organizational patterns and provides information about the driving forces behind the growth of the networks. In the similarity network, we find a strong correlation between clusters of artists and musical genres. On the other hand, the collaboration n...

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Journal of Applied Physics : Energy and angle spectra of sputtered...

By: P. S. Krstic, C. O. Reinhold, and S. J. Stuart

Description: We study the translational, vibrational, and rotational energy spectra of atoms and molecules reflected or sputtered from deuterated amorphous carbon surfaces by impact of low-energy (1–30 eV) deuterium atoms. Both the rovibrational and translational energies of sputtered deuterium molecules are found to be close to 1 eV over the whole impact energy range, with approximate equipartition between rotational and vibrational modes, particularly at the higher imp...

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Review of Scientific Instruments : Improvement of temporal resolut...

By: Hideo Sato-Akaba, Hirotada Fujii, and Hiroshi Hirata

Description: This paper describes improved temporal resolution for three-dimensional (3D) continuous-wave electron paramagnetic resonance (EPR) imaging. To improve temporal resolution, the duration of magnetic filed scanning that is used to obtain an EPR spectrum for each projection was reduced to 40 ms. The Helmholtz coil pair for field scanning was driven by triangular waves. The uniform distribution of projections was also used to reduce the number of projections for ...

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Chaos : Synchronization of a class of chaotic systems with fully u...

By: M. Roopaei and M. Zolghadri Jahromi

Description: In this paper, an adaptive sliding mode control method for synchronization of a class of chaotic systems with fully unknown parameters is introduced. In this method, no knowledge of the bounds of parameters is required in advance and the parameters are updated through an adaptive control process. We use our proposed method to synchronize two chaotic gyros, which has been the subject of intense study during the recent years for its application in the navigati...

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The Journal of Chemical Physics : Monte Carlo simulations of amphi...

By: Jonathan R. Davis and Athanassios Z. Panagiotopoulos

Description: Grand canonical Monte Carlo simulations on a cubic lattice are used to examine aggregation and phase separation of model amphiphiles with bulky head groups. The amphiphiles studied consist of a rigid, roughly spherical nanoparticle attached to one or more flexible chains. Overlapping distributions of energy and density are combined via histogram reweighting to obtain the free energy and osmotic pressure as a function of temperature and concentration. Finite ...

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Applied Physics Letters : Depth-resolved holographic optical coher...

By: M. Salvador, J. Prauzner, S. Köber, K. Meerholz, K. Jeong et al

Description: We present coherence-gated holographic imaging using a highly sensitive photorefractive PR polymer composite as the recording medium. Due to the high sensitivity of the composite holographic recording at intensities as low as 5 mW/cm2 allowed for a frame exposure time of only 500 ms. Motivated by regenerative medical applications, we demonstrate optical depth sectioning of a polymer foam for use as a cell culture matrix. An axial resolution of 18 m and a ...

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The Journal of Chemical Physics : Optical absorption of small silv...

By: M. Harb, F. Rabilloud, D. Simon, A. Rydlo, S. Lecoultre et al

Description: We present a joint theoretical and experimental investigation of the absorption spectra of silver clusters Agn (4 ≤ n ≤ 22). The experimental spectra of clusters isolated in an Ar matrix are compared with the calculated ones in the framework of the time-dependent density functional theory. The analysis of the molecular transitions indicates that the s-electrons are responsible for the optical response of small clusters (n ≤ 8) while the d-electrons play a cr...

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Journal of Applied Physics : Optical and structural properties of ...

By: D. Singh, K. Singh, B. S. Bajwa, G. S. Mudahar, D. P. Singh et al

Description: The density, molar volume, optical energy bandgap, and infrared absorption spectra in the range 400–4000 nm of borate glasses with composition 2xLi2O–xAl2O3–(1–3x)B2O3 (x varying from 0.10 to 0.18 mol fraction) prepared by conventional melt quench technique have been measured before and after successive γ-ray irradiation at the dose of 2.5 K Gy to elucidate the effect of gamma irradiation on such glasses. The radiation induced defects created by γ-ray and th...

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Applied Physics Letters : Influence of polarity on carrier transpo...

By: Yoshinobu Kawaguchi, Chia-Yen Huang, Yuh-Renn Wu, Qimin Yan, Chih-Chien Pan et al

Description: We investigate the influence of polarity on carrier transport in single-quantum-well and multiple-quantum-well (MQW) light-emitting diodes (LEDs) grown on the semipolar (20¯21) and (20¯21) orientations of free-standing GaN. For semipolar MQW LEDs with the opposite polarity to conventional Ga-polar c-plane LEDs, the polarization-related electric field in the QWs results in an additional energy barrier for carriers to escape the QWs. We show that semipolar (20...

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Physics of Fluids : Modeling of the subfilter scalar dissipation r...

By: G. Balarac, H. Pitsch, and V. Raman

Description: In this work, modeling of the subfilter scalar dissipation rate is addressed. First, the best set of quantities to write a model is determined using the concept of optimal estimators. This study shows that the best approach is to assume a proportionality between the turbulent time scale and turbulent scalar mixing time scale. It is shown that the turbulent time scale should be defined by the subfilter kinetic energy. To define the coefficient appearing in th...

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