Modulation of Mechanical Interactions by Local Piezoelectric Effects

Piezoelectricity is a well‐established property of biological materials, yet its functional role has remained unclear. Here, a mechanical effect of piezoelectric domains resulting from collagen fibril organisation is demonstrated, and its role in tissue function and application to material design is described. Using a combination of scanning probe and nonlinear optical microscopy, a hierarchical structuring of piezoelectric domains in collagen‐rich tissues is observed, and their mechanical effects are explored in silico. Local electrostatic attraction and repulsion due to shear piezoelectricity in these domains modulate fibril interactions from the tens of nanometre (single fibril interactions) to the tens of micron (fibre interactions) level, analogous to modulated friction effects. The manipulation of domain size and organisation thus provides a capacity to tune energy storage, dissipation, stiffness, and damage resistance.     

An EKV-based high voltage MOSFET model with improved mobility and drift model

An EKV-based high voltage MOSFET model is presented. The intrinsic channel model is derived based on the charge based EKV-formalism. An improved mobility model is used for the modeling of the intrinsic channel to improve the DC characteristics. The model uses second order dependence on the gate bias and an extra parameter for the smoothening of the saturation voltage of the intrinsic drain. An improved drift model [Chauhan YS, Anghel C, Krummenacher F, Ionescu AM, Declercq M, Gillon R, et al. A highly scalable high voltage MOSFET model. In: IEEE European solid-state device research conference (ESSDERC), September 2006. p. 270–3; Chauhan YS, Anghel C, Krummenacher F, Maier C, Gillon R, Bakeroot B, et al. Scalable general high voltage MOSFET model including quasi-saturation and self-heating effect. Solid State Electron 2006;50(11–12):1801–13] is used for the modeling of the drift region, which gives smoother transition on output characteristics and also models well the quasi-saturation region of high voltage MOSFETs. First, the model is validated on the numerical device simulation of the VDMOS transistor and then, on the measured characteristics of the SOI-LDMOS transistor. The accuracy of the model is better than our previous model [Chauhan YS, Anghel C, Krummenacher F, Maier C, Gillon R, Bakeroot B, et al. Scalable general high voltage MOSFET model including quasi-saturation and self-heating effect. Solid State Electron 2006;50(11–12):1801–13] especially in the quasi-saturation region of output characteristics.     

An Overview and Future Perspectives of Aluminum Batteries

A critical overview of the latest developments in the aluminum battery technologies is reported. The substitution of lithium with alternative metal anodes characterized by lower cost and higher abundance is nowadays one of the most widely explored paths to reduce the cost of electrochemical storage systems and enable long‐term sustainability. Aluminum based secondary batteries could be a viable alternative to the present Li‐ion technology because of their high volumetric capacity (8040 mAh cm^?3 for Al vs 2046 mAh cm^?3 for Li). Additionally, the low cost aluminum makes these batteries appealing for large‐scale electrical energy storage. Here, we describe the evolution of the various aluminum systems, starting from those based on aqueous electrolytes to, in more details, those based on non‐aqueous electrolytes. Particular attention has been dedicated to the latest development of electrolytic media characterized by low reactivity towards other cell components. The attention is then focused on electrode materials enabling the reversible aluminum intercalation‐deintercalation process. Finally, we touch on the topic of high‐capacity aluminum‐sulfur batteries, attempting to forecast their chances to reach the status of practical energy storage systems.     

Communities of shared interests and cognitive bridges: the case of the anti-vaccination movement on Twitter

Scientometrics - This paper presents an analysis of the anti-vaccination movement’s referencing of research articles on the topic of vaccination in the social media network Twitter. Drawing...     

A monotone nonlinear finite volume method for approximating diffusion operators on general meshes

The basic principles of the discrete duality and nonlinear monotone finite volume methods are combined in order to obtain a new monotone nonlinear finite volume method for the approximation of diffusion operators on general meshes. Numerical results highlight both the second‐order accuracy of this method on general meshes and its capability to deal with challenging anisotropic diffusion problems on various computational domains. Copyright © 2016 John Wiley & Sons, Ltd.     

Patterned radial GaAs nanopillar solar cells

Photovoltaic devices using GaAs nanopillar radial p-n junctions are demonstrated by means of catalyst-free selective-area metal-organic chemical vapor deposition. Dense, large-area, lithographically defined vertical arrays of nanowires with uniform spacing and dimensions allow for power conversion efficiencies for this material system of 2.54% (AM 1.5 G) and high rectification ratio of 213 (at ±1 V). The absence of metal catalyst contamination results in leakage currents of ～236 nA at -1 V. High-resolution scanning photocurrent microscopy measurements reveal the independent functioning of each nanowire in the array with an individual peak photocurrent of ～1 nA at 544 nm. External quantum efficiency shows that the photocarrier extraction highly depends on the degenerately doped transparent contact oxide. Two different top electrode schemes are adopted and characterized in terms of Hall, sheet resistance, and optical transmittance measurements.     

Comparative Studies of the Superconducting Properties of Bi2Sr2CaCu2O8+δ and Bi1.7Pb0.3Sr2CaCu2O8+δ/Ag Random Composites

We report the results of the study of the resistive transition and the screening effect on similar random composites made of a silver matrix containing sintered superconducting grains of bismuth phase with two different stoichiometries. We show that most of the observed behaviors are compatible with a phenomenological approach in which the intergrain junctions behave as weak links whose the state depends strongly on temperature and field. We find that these links a much weaker in one of the series of samples.     

Design of evolutionary algorithms-A statistical perspective

This paper describes a statistical method that helps to find good parameter settings for evolutionary algorithms. The method builds a functional relationship between the algorithm's performance and its parameter values. This relationship-a statistical model-can be identified thanks to simulation data. Estimation and test procedures are used to evaluate the effect of parameter variation. In addition, good parameter settings can be investigated with a reduced number of experiments. Problem labeling can also be considered as a model variable and the method enables identifying classes of problems for which the algorithm behaves similarly. Defining such classes increases the quality of estimations without increasing the computational cost     

Borderline pathology: An integration of cognitive therapy and psychodynamic therapy.

Because of the belated interest in borderline pathology outside of the psychoanalytic arena, there is a relative paucity of integrative models for the treatment and understanding of borderline pathology. This article compares and contrasts the practice of A. T. Beck and A. Freeman's (1990) cognitive treatment of borderline pathology with 0. F. Kernberg's (Kernberg, Selzer, Koenigsberg, Carr, & Appelbaum, 1989) psychodynamic approach. An integrative model of borderline pathology is proposed, building on Beck and Freeman's and Kernberg's shared use of the notion of schema-representation. The practice implications of the proposed integrative model are consequently entertained. A brief case study is provided to illustrate the integration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasmall Nanoplatforms as Calcium‐Responsive Contrast Agents for Magnetic Resonance Imaging

The preparation of ultrasmall and rigid platforms (USRPs) that are covalently coupled to macrocycle‐based, calcium‐responsive/smart contrast agents (SCAs), and the initial in vitro and in vivo validation of the resulting nanosized probes (SCA‐USRPs) by means of magnetic resonance imaging (MRI) is reported. The synthetic procedure is robust, allowing preparation of the SCA‐USRPs on a multigram scale. The resulting platforms display the desired MRI activity—i.e., longitudinal relaxivity increases almost twice at 7 T magnetic field strength upon saturation with Ca²⁺. Cell viability is probed with the MTT assay using HEK‐293 cells, which show good tolerance for lower contrast agent concentrations over longer periods of time. On intravenous administration of SCA‐USRPs in living mice, MRI studies indicate their rapid accumulation in the renal pelvis and parenchyma. Importantly, the MRI signal increases in both kidney compartments when CaCl₂ is also administrated. Laser‐induced breakdown spectroscopy experiments confirm accumulation of SCA‐USRPs in the renal cortex. To the best of our knowledge, these are the first studies which demonstrate calcium‐sensitive MRI signal changes in vivo. Continuing contrast agent and MRI protocol optimizations should lead to wider application of these responsive probes and development of superior functional methods for monitoring calcium‐dependent physiological and pathological processes in a dynamic manner.