In situ nanomechanical measurements of interfacial strength in membrane-embedded chemically functionalized Si microwires for flexible solar cells

Arrays of vertically aligned Si microwires embedded in polydimethylsiloxane (PDMS) have emerged as a promising candidate for use in solar energy conversion devices. Such structures are lightweight and concurrently demonstrate competitive efficiency and mechanical flexibility. To ensure reliable functioning under bending and flexing, strong interfacial adhesion between the nanowire and the matrix is needed. In situ uniaxial tensile tests of individual, chemically functionalized, Si microwires embedded in a compliant PDMS matrix reveal that chemical functionality on Si microwire surfaces is directly correlated with interfacial adhesion strength. Chemical functionalization can therefore serve as an effective methodology for accessing a wide range of interfacial adhesion between the rigid constituents and the soft polymer matrix; the adhesion can be quantified by measuring the mechanical strength of such systems.     

Ultrahigh strength of dislocation-free Ni3Al nanocubes

Individual Ni(3) Al nanocubes under pressure are investigated by comparing the compressive strength of both dislocation-free and irradiated Ni(3) Al nanocubes. The results are dicussed in light of the size-dependent and size-independent strength of face-centered cubic (fcc) nanocrystals in the framework of dislocation nucleation at free surfaces. This study sheds more light on the understanding of fundamental deformation mechanisms and size-affected strength in dislocation-free metallic nanocrystals.     

Deformation mechanisms in nanotwinned metal nanopillars

Nanotwinned metals are attractive in many applications because they simultaneously demonstrate high strength and high ductility, characteristics that are usually thought to be mutually exclusive. However, most nanotwinned metals are produced in polycrystalline forms and therefore contain randomly oriented twin and grain boundaries making it difficult to determine the origins of their useful mechanical properties. Here, we report the fabrication of arrays of vertically aligned copper nanopillars that contain a very high density of periodic twin boundaries and no grain boundaries or other microstructural features. We use tension experiments, transmission electron microscopy and atomistic simulations to investigate the influence of diameter, twin-boundary spacing and twin-boundary orientation on the mechanical responses of individual nanopillars. We observe a brittle-to-ductile transition in samples with orthogonally oriented twin boundaries as the twin-boundary spacing decreases below a critical value (～3-4?nm for copper). We also find that nanopillars with slanted twin boundaries deform via shear offsets and significant detwinning. The ability to decouple nanotwins from other microstructural features should lead to an improved understanding of the mechanical properties of nanotwinned metals.     

Temperature and frequency dependences of real part of impedance in the FeCoZr-doped PZT nanogranular composites

The study of carrier transport in granular nanocomposite films consisting of ferromagnetic Fe₄₅Co₄₅Zr₁₀ alloy nanoparticles embedded in a low-conductive Pb₈₁Sr₄(Na₅Bi₅)₁₅(Zr_57.5Ti_42.5)O₃ matrix has been performed. Real part of the impedance of the nanocomposites was studied as a function of composition, temperature and frequency, for the samples with 25 ?? x ?? 80 at.%, deposited by ion-beam sputtering in Ar + O₂ gas mixture at the oxygen pressures of $P_{O_2 } $ = 2.4·10^?3 and 3.7·10^?3 Pa. It has been proved that approaching the threshold concentration, x _C in the FeCoZr alloy resulted in the transition from high-ohmic to low-ohmic state with the x increase, without the change of hopping mechanism of carrier transport.     

Edge enhancement of color images using a digital micromirror device

A method for orientation-selective enhancement of edges in color images is proposed. The method utilizes the capacity of digital micromirror devices to generate a positive and a negative color replica of the image used as input. When both images are slightly displaced and imagined together, one obtains an image with enhanced edges. The proposed technique does not require a coherent light source or precise alignment. The proposed method could be potentially useful for processing large image sequences in real time. Validation experiments are presented.     

Spark plasma sintering of a p-type Si1?x Ge x alloy: identification of the densification mechanism by isothermal and anisothermal methods

Spark plasma sintering of a p-type Si_0.795Ge_0.200B_0.005 alloy has been investigated in vacuum, in the 400–1200 °C temperature range. The densification mechanism has been determined using isothermal and anisothermal methods. In spite of a slight material degradation for the highest sintering temperatures (occurrence of cristobalite nodules homogeneously dispersed in intergranular and intragranular positions), it is proposed that densification proceeds by grain boundary sliding accommodated most probably by silicon volume diffusion. The microstructure observation of several sintered samples using transmission electron microscopy supports the densification mechanism advanced. Because the elemental grains remain mostly equiaxe whatever the sintering conditions, a grain intercalation mechanism may be also implicated during densification.     

On the relationship between lateralized brain function and orienting asymmetries.

[Correction Notice: An erratum for this article was reported in Vol 125(1) of Behavioral Neuroscience (see record 2011-02594-005). In the article “On the Relationship Between Lateralized Brain Function and Orienting Asymmetries,” by Christoph Teufel, Asif A. Ghazanfar, and Julia Fischer (Behavioral Neuroscience, 2010, Vol. 124, No. 4, pp. 437–445), we wrote that “the likelihood of obtaining at least one significant result at p n. The probability of obtaining at least one significant result is therefore 1 — (1— α)n.] Hemispheric specializations for language perception constitute one of the classic topic in cognitive neuroscience. Evidence has accumulated to suggest that lateralized acoustic processing is not restricted to humans but is also found in numerous animal species. One of the methods used to track such lateralization is the orienting-asymmetry paradigm, a simple, noninvasive means to study lateralization that has been applied to a range of different species ranging from harpy eagles to humans. Here we summarize and compare the results of studies employing the orienting-asymmetry paradigm, showing that these studies yield largely inconsistent results. We critically discuss the methodology's implicit assumptions and conclude that the empirical inconsistencies produced by the orienting-asymmetry paradigm, and the lack of sufficient evidence supporting the paradigm's underlying assumptions, warrant serious caution when interpreting results obtained by the method. Nontrivial interpretations of orienting-asymmetry results will require a much better understanding of how lateralized brain functions interact with overt behaviors. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Optimization of solid‐phase microextraction methods for GC‐MS determination of terpenes in wine

Solid‐phase microextraction using a 100 µm poly(dimethylsiloxane) fiber, followed by gas chromatography–mass spectrometry determination, has been optimized for the analysis of some terpenes in wine samples. The best results were obtained by direct immersion of the fiber using a sampling period of 15 min with constant magnetic stirring (1100 rpm) and an extraction temperature of 20 °C. The sample volume was 7 ml with 25% NaCl, in a 15 ml capped vial. Desorption was performed directly in the gas chromatograph injector port over 5 min at 250 °C using the splitless mode. The method is sensitive, with detection limits between 11 and 25 µg l^?1, precise, with variation coefficients in the range 1.28–3.71%, and linear over more than one order of magnitude. The related conditions were used for wine sample analyses with recoveries between 71.8 and 90.9%. Solid‐phase microextraction remains an attractive alternative technique due to its rapidity and because it is a solvent‐free extraction. Copyright © 2005 Society of Chemical Industry     

Interpersonal Problems and the Outcome of Interpersonally Oriented Psychodynamic Treatment of GAD.

The present study tested hypotheses concerning interpersonal problems and the course of brief psychodynamic treatment of generalized anxiety disorder (GAD). The authors found that the largest changes from pre- to post-therapy were evident for the Nonassertive, Exploitable, and Intrusive subscales of the Inventory of Interpersonal Problems. Relatively small changes were seen on the Overly Nurturant subscale, which was hypothesized to be most relevant to GAD. Changes in interpersonal problems were significantly associated with improvement in symptoms and worry. Brief dynamic therapy was not found to uniquely improve interpersonal problems compared with supportive therapy, although the psychodynamic approach was statistically and clinically superior to supportive therapy on symptomatic remission rates. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Novelty-seeking temperament in captive stumptail macaques (macaca arctoides) and spider monkeys (ateles geoffroyi).

Novelty-seeking temperament is defined as the reaction to novel or risk situations and objects, and by the global disposition to explore such stimuli. Our purpose was to describe and compare this trait in primates. For this purpose, a risk-taking Index, a curiosity index, and a novelty-seeking index were correlated to several biosocial variables using 22 captive stumptail macaques (Macaca arctoides) and 7 captive spider monkeys (Ateles geoffroyi). Spider monkeys scored higher than macaques, males of both species scored higher than females, and dominant macaques were evaluated as more novelty seekers. We suggest that these differences may be because of, among other reasons, the particular social system of each species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)