The Absence of a Shape Bias in Children's Word Learning.

There is debate about whether preschool-age children interpret words as referring to kinds or to classes defined by shape similarity. The authors argue that the shape bias reported in previous studies is a task-induced artifact rather than a genuine word-learning strategy. In particular, children were forced to extend an object's novel label to one of several stand-alone, simple-shaped items, including a same-shape option from a different category and a different-shape option from the same superordinate category. Across 6 experiments, the authors found that the shape bias was eliminated (a) when the objects were more complex, (b) when they were presented in context, or (c) when children were no longer forced to choose. Moreover, children preferred the different-shape category alternatives when these were part of the same basic-level category as the target. The present experiments suggest that children seek out objects of the same kind when presented with a novel label, even if they are sometimes unable to identify the relevant kinds on their own. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

A ternary thin film combinatorial materials library of the valve metal system Hf–Ta–Ti obtained by co-sputtering was studied. The microstructural and crystallographic analysis of the obtained compositions revealed a crystalline and textured surface, with the exception of compositions with Ta concentration above 48 at.% which are amorphous and show a flat surface. Electrochemical anodization of the composition spread thin films was used for analysing the growth of the mixed surface oxides. Oxide formation factors, obtained from the potentiodynamic anodization curves, as well as the dielectric constants and electrical resistances, obtained from electrochemical impedance spectroscopy, were mapped along two dimensions of the library using a scanning droplet cell microscope. The semiconducting properties of the anodic oxides were mapped using Mott–Schottky analysis. The degree of oxide mixing was analysed qualitatively using x-ray photoelectron spectroscopy depth profiling. A quantitative analysis of the surface oxides was performed and correlated to the as-deposited metal thin film compositions. In the concurrent transport of the three metal cations during oxide growth a clear speed order of Ti > Hf > Ta was proven.     

Interactions and Chemical Transformations of Coronene Inside and Outside Carbon Nanotubes

By exposing flat and curved carbon surfaces to coronene, a variety of van der Waals hybrid heterostructures are prepared, including coronene encapsulated in carbon nanotubes, and coronene and dicoronylene adsorbed on nanotubes or graphite via π–π interactions. The structure of the final product is determined by the temperature of the experiment and the curvature of the carbon surface. While at temperatures below and close to the sublimation point of coronene, nanotubes with suitable diameters are filled with single coronene molecules, at higher temperatures additional dimerization and oligomerization of coronene occurs on the surface of carbon nanotubes. The fact that dicoronylene and possible higher oligomers are formed at lower temperatures than expected for vapor‐phase polymerization indicates the active role of the carbon surface used primarily as template. Removal of adsorbed species from the nanotube surface is of utmost importance for reliable characterization of encapsulated molecules: it is demonstrated that the green fluorescence attributed previously to encapsulated coronene is instead caused by dicoronylene adsorbed on the surface which can be solubilized and removed using surfactants. After removing most of the adsorbed layer, a combination of Raman spectroscopy and transmission electron microscopy was employed to follow the transformation dynamics of coronene molecules inside nanotubes.     

Directed 2D-to-3D pattern transfer method for controlled fabrication of topologically complex 3D features in silicon

A process that allows control over the 3D motion of catalyst nanostructures during metal-assisted chemical etching by their local pinning prior to etching is demonstrated. The pinning material acts as a fulcrum for rotation of the catalyst structures resulting in etching of silicon features with rotational geometry.     

Elastic properties of porous media in the vicinity of the percolation limit

A new approach to calculation of the elastic bulk modulus of low consolidated porous media in the vicinity of the percolation limit under dry and saturated conditions is developed based on a physical consolidation model of rocks and the classical contact theory developed by H. Hertz in 1882. The derived analytical relationships for the elastic bulk modulus, which take into account the structural architecture of packing, are compared with theoretical predictions from popular micromechanic theories, Hashin–Shtrikman strict bounds as well as with experimental results available for low consolidated granular materials. The latter comparison demonstrates a good agreement under both dry and water saturated conditions.     

Peculiarities of Neurostimulation by Intense Nanosecond Pulsed Electric Fields: How to Avoid Firing in Peripheral Nerve Fibers

Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength–duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.     

Alkylation of Hydroquinone with tert-butanol over Silica-immobilized Triflate Derivatives

Friedel-Crafts alkylations of α-methylnaphthalene with various alkylating agents were first carried out in the presence of methanesulfonic acid (MeSA). The Brønsted acid catalyst MeSA exhibited outstanding catalytic performance, and was found to be excellent catalyst and solvent for alkylation reaction of aromatic hydrocarbon. It’s found that alkenes can be used as excellent alkylating agent for alkylation of α-methylnaphthalene. The effects of various reaction parameters like type of alkylating agent, dosages of catalysts, reaction temperature and reaction time were investigated in detail. Moreover, the performance of reuse for catalysts was also studied. It’s found that, under the optimal reaction conditions, more than 90% of conversion for olefins and 100% of selectivity for the desired products were obtained. Compared with traditional catalysis technology, the reaction, catalyzed by MeSA catalyst, no volatile solvents needed, good selectivity for desired products could be obtained. The catalyst can be isolated easily from the reaction mixtures by decantation, and was successfully reused. The methanesulfonic acid could be considered as environmentally friendly novel catalyst and solvent for long-chain alkylation of α-methylnaphthalene with alkenes. The catalytic reaction mechanism for alkylation in the presence of MeSA was proposed as well.     

Recognition and inspection of two-dimensional industrial parts using subpolygons

A model-based scene analysis for the recognition of imperfect and possibly occluded two-dimensional (2D) industrial parts is described. The means of recognition leads reliably to the correct association of the sides making up the unknown object to those of the model. Both the scene polygon and the model are divided into pairs of complementary subpolygons. This is done by a cutting line drawn parallel and close to a selected side. The subpolygons from the object are compared to all possible subpolygons from the model. Invariant moments are used in the analysis. A matching process using clusters of mutually consistent features is used to hypothesize the identity of the object. Examples are given to illustrate the method.