Opto-electronic properties of rough LP-CVD ZnO:B for use as TCO in thin-film silicon solar cells

Polycrystalline Boron-doped ZnO films deposited by low pressure chemical vapor deposition technique are developed for their use as transparent contacts for thin-film silicon solar cells. The size of the columnar grains that constitute the ZnO films is related to their light scattering capability, which has a direct influence on the current generation in thin-film silicon solar cells. Furthermore, if the doping level of the ZnO films is kept below 1 × 10²⁰ cm^− 3, the electron mobility can be drastically enhanced by growing large grains, and the free carrier absorption is reduced. All these considerations have been taken in account to develop ZnO films finely optimized for the fabrication of microcrystalline thin-film silicon solar cells. These TCO allow the achievement of solar cell conversion efficiencies close to 10%.     

A feasibility study on the use of anthropometric variables to make muscle–computer interface more practical

High classification accuracy has been achieved for muscle–computer interfaces (MCIs) based on surface electromyography (EMG) recognition in many recent works with an increasing number of discriminated movements. However, there are many limitations to use these interfaces in the real-world contexts. One of the major problems is compatibility. Designing and training the classification EMG system for a particular individual user is needed in order to reach high accuracy. If the system can calibrate itself automatically/semi-automatically, the development of standard interfaces that are compatible with almost any user could be possible. Twelve anthropometric variables, a measurement of body dimensions, have been proposed and used to calibrate the system in two different ways: a weighting factor for a classifier and a normalizing value for EMG features. The experimental results showed that a number of relationships between anthropometric variables and EMG time-domain features from upper-limb muscles and movements are statistically strong (average r=0.71?0.80) and significant (p<0.05). In this paper, the feasibility to use anthropometric variables to calibrate the EMG classification system is shown obviously and the proposed calibration technique is suggested to further improve the robustness and practical use of MCIs based on EMG pattern recognition.     

Microstructural investigation of magnetic CoFe2O4 nanowires inside carbon nanotubes by electron tomography

Magnetic nanowires of CoFe 2O4 were casted inside the channel of multiwall carbon nanotubes by mild chemical synthesis. A detailed investigation of these nanowires was performed using mainly the electron tomography technique; this study provides a complete characterization of their microstructure in terms of the spatial organization and the size distribution of individual particles forming the nanowire as well as its residual porosity. In particular, we have shown that the size of the CoFe 2O4 monocrystalline particles is closely dependent on the location of the particle within the nanotube, i.e., small particles close to the tube tip (5 nm) and bigger particles inside the tube channel (15 nm). As the theoretical critical size for superparamagnetic relaxation in CoFe 2O4 is estimated within the range of 4-9 nm, the size distribution obtained by 3D-TEM agrees with the Mossbauer study that suggests the presence of two different magnetic components inside the nanowire. We have shown also that, by using this preparation method and for this internal diameter of nanotube, the CoFe 2O4 nanowire exhibits a continuous structure along the tube, has a residual porosity of 38%, and can fill the tube at only 50%, parameters which influence in a significant manner the magnetic behavior of this system.     

Electrochemical oxidation of hydrophobic compounds in aqueous micellar solutions and oil-in-water emulsions

The electrochemical oxidation of ferrocene (Fc) and tetrathiofulvalene (TTF) has been investigated in micelles and dodecane-in-water emulsions in order to compare the diffusional process involved in these systems. It is found that the diffusion coefficients of Fc and TTF, determined from the observed limiting currents at the rotating disc electrode, are governed by the solubilization equilibrium of the neutral substrates which are predominantly solubilized in the micelle or oil-droplet phase. In the emulsion, the cyclic voltammograms show that the current is controlled also by the rate constants of the substrate partition, which depend on the size of the emulsion droplets. The determination of the diffusion coefficients of Fc⁺ and TTF⁺, produced in situ by controlled potential electrolysis, showed that, except in SDS micellar solutions, the monocation radicals are solubilized mainly in the aqueous phase. As a result, the diffusion coefficients of the species involved in the redox system are different. In the case of TTF, the above results have a great influence upon the second oxidation step TTF⁺ → TTF²⁺. Indeed, the homogeneous solution reaction between TTF and the electrogenerated dication TTF²⁺ leads to the monocation TTF⁺ which diffuses more rapidly than its parent molecule TTF. The ratios of the two waves in cyclic and rotating disc electrode voltammetry show that the enhancement of the second wave depends mainly on the difference between the diffusion coefficients of TTF and TTF⁺ and that the nature of the solution or the size of the disperse phase has little influence upon the reaction rate of the homogeneous solution reaction.     

Electrochemical Chromium(III) Oxide Coatings on Non-oxide Ceramic Substrates

SiC and TiB₂ were electrochemically coated with Cr₂O₃ from a 0.1 M aqueous solution of chromium nitrate hydrate with ethanol additives. On both substrate materials poly-crystalline Cr₂O₃ was formed at current densities from 5 to 50 mA/cm² and deposition durations of 5 to 30 min. The coating weight increased with current density and with deposition time. The as-deposited coatings contained microcracks due to drying shrinkage. Microstructural observations indicate that sintering of the Cr₂O₃ coatings on TiB₂ at 1100°C for 1 n in a reducing atmosphere in a closed graphite crucible causes the densification of the coating via a liquid phase, which forms by oxidation of TiB₂. Under similar conditions, the Cr₂O₃ coatings on SiC may be sintered via an evaporation–condensation mechanism.     

Anger and time perception in children.

The present study investigated age-related variations in judgments of the duration of angry facial expressions compared with neutral facial expressions. Children aged 3, 5, and 8 years were tested on a temporal bisection task using angry and neutral female faces. Results revealed that, in all age groups, children judged the duration of angry faces to be longer than that of neutral faces. Findings are discussed in the framework of internal clock models and the adaptive function of emotion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electron microprobe and synchrotron x-ray fluorescence mapping of the heterogeneous distribution of copper in high-copper vineyard soils

The response of microorganisms to metal contamination of soils varies significantly from one investigation to another. One explanation is that metals are heterogeneously distributed at spatial scales relevant to microbes and that microoorganisms are able to avoid zones of intense contamination. This article aims to assess the microscale distribution of Cu in a vineyard soil. The spatial distribution of Cu was measured at two resolutions (0.3 mm and 20 microm) in thin sections of the surface 4 cm of undisturbed soil by electron microprobe and synchrotron X-ray microfluo-rescence spectroscopy. Bulk physicochemical analyses of Cu, pH, organic matter, texture, and mineralogy were performed. The results indicate that the Cu distribution is strongly heterogeneous at both scales of observation. Entire regions of the thin sections are virtually devoid of Cu, whereas highly localized "hotspots" have Cu signal intensities thousands of times higher than background. The distribution of Rb, or Al and Si, indicators of clay minerals, or Fe (iron (hydr)oxides), show that Cu is not preferentially associated with these mineral phases. Instead, Cu hotspots are associated with particulate organic matter. These observations suggest modification of current sampling protocols, and design of ecotoxicological experiments involving microorganisms, for contaminated soils.     

Identification of design motifs with pattern matching algorithms

Design patterns are important in software maintenance because they help in understanding and re-engineering systems. They propose design motifs, solutions to recurring design problems. The identification of occurrences of design motifs in large systems consists of identifying classes whose structure and organization match exactly or approximately the structure and organization of classes as suggested by the motif. We adapt two classical approximate string matching algorithms based on automata simulation and bit-vector processing to efficiently identify exact and approximate occurrences of motifs. We then carry out two case studies to show the performance, precision, and recall of our algorithms. In the first case study, we assess the performance of our algorithms on seven medium-to-large systems. In the second case study, we compare our approach with three existing approaches (an explanation-based constraint approach, a metric-enhanced explanation-based constraint approach, and a similarity scoring approach) by applying the algorithms on three small-to-medium size systems, JHotDraw, Juzzle, and QuickUML. Our studies show that approximate string matching based on bit-vector processing provides efficient algorithms to identify design motifs.     

The invasion of a large lake by the Eurasian genotype of common reed: The influence of roads and residential construction

The Eurasian genotype of common reed (Phragmites australis) is one of the most aggressive plant invading North American wetlands. There is, however, little published evidence on establishment patterns of populations along lakes of the St. Lawrence River–Great Lakes watershed. We tested the hypothesis that the recent invasion of Great Lake Saint-François (Québec, Canada) by common reed was facilitated by a dense road system and by an intense residence construction activity along lakeshores. A total of 345 and 2914 reed stands were mapped along lakeshores, and along the road system of the study area, respectively. The probability of finding a reed stand on a lakeshore increases with the proximity of the lake's outlet, and of a paved road, but decreases with the proximity of a residence built since 1990. It is likely that common reed first spread along the road system, and that wind dispersal of seeds then favored the establishment of populations on lakeshores. Our model does not support the hypothesis that residential construction facilitated the establishment of reed stands, probably because the recent residential construction boom occurred essentially in the southern part of the lake, where the number of roadside reed populations is much lower than in the northern part (lower seed rain). The invasion of Great Lake Saint-François shows that the spread of the plant is not restricted to major river or road systems. Large or small lakes, if submitted to intense diaspore pressure, can also be at risk.     

Proliferative effects of synthetic peptides from β-lactoglobulin and α-lactalbumin on murine splenocytes

Eleven peptides, selected on the basis of physicochemical characteristics and their theoretical release from β-lactoglobulin (β-Lg) and α-lactalbumin (α-La) by trypsin or chymotrypsin, were chemically synthesised to evaluate their immunomodulating properties. Murine splenocyte proliferation in the absence and presence of mitogen and different peptide concentrations were measured after 72–96 h incubations. β-Lg f78–83 had no effect on proliferation; β-Lg f15–20, f55–60, f84–91, f92–105, f139–148, f142–148 and α-La f10–16 stimulated proliferation to different extents; β-Lg f1–8, f102–105 and α-La f104–108 showed a cytotoxic effect. Regression analysis revealed the relationship of positive charge, hydrophobicity and length to the stimulatory proliferative effect. β-Lg f15–20, f55–60 and f139–148 also induced various inhibiting and/or stimulating effects on cytokine secretion. The results confirm that peptides releasable by digestive enzymes from α-La and β-Lg have the potential to influence the specific immune response through the modulation of splenocyte proliferation and cytokine secretion.