Retardance of chalcogenide thin films grown by the oblique-angle-deposition technique

Columnar and chevronic thin films of GeSbSe chalcogenide glasses were grown by the oblique-angle-deposition technique. These thin films were found to exhibit dielectric anisotropy in the near-infrared regime. The retardance of any of the fabricated thin films was found to increase linearly with the thickness. Columnar thin films exhibited significantly lower retardance per unit thickness than chevronic thin films. The experimental results indicate the potential of these thin films for near-infrared polarizers.     

Bifurcation diagrams for the moments of a kinetic type model of keloid–immune system competition

The mathematical modelling of the keloid disease triggered by a virus has been recently investigated by one of the authors, Bianca (2011) [5], where it was shown that the model is able to depict the emerging behaviours which occur during the keloid formation.This paper deals with further numerical investigations of that model related to the bifurcation analysis of the measurable macroscopic variables associated to each functional subsystem. It is shown that there exists a critical value of a bifurcation parameter separating situations where the immune system controls the keloid formation from those where malignant effects are not contrasted.     

Experimental analysis of microcogenerators based on different prime movers

The European Union recently established an ambitious target by 2020 that consists of increasing the utilization of renewable energy up to 20%, reducing its overall pollutant emissions by at least 20%, and achieving a primary energy saving of 20% compared to reported 1990 levels. This aim can only be realized with strong effort in different sectors, such as residential, commercial, industry, tertiary, transportation. In particular in the European Union, a remarkable contribution to energy consumption and CO₂ emissions is concentrated in residential and commercial sector. The introduction of more efficient technologies in these sectors could help in achieving the results expected by 2020. An option is given by cogeneration, defined as the combined “production” of electric and/or mechanical and thermal energy starting from single energy source. This technology could be considered one of the first elements to save primary energy, to avoid network losses and to reduce greenhouse gas emissions. In particular, this article focuses on the microcogeneration (electric power ≤ 15 kW), which represents a valid and interesting application for residential and light commercial users. The energy, economic and environmental implications due to the use of small scale cogeneration systems were reported, by means of an experimental research activity performed by the authors and other researchers.     

Attention allocation modulates the processing of hierarchical visual patterns: A comparative analysis of capuchin monkeys (Cebus apella) and humans.

Humans show a global advantage when processing hierarchical visual patterns, and they detect the global level of stimulus structure more accurately and faster than the local level in several stimulus contexts. By contrast, capuchins (Cebus apella) and other monkey species show a strong local advantage. A key factor which, if manipulated, could cause an inversion of this effect in monkeys is still to be found. In this study, we examined whether it was possible to induce attention allocation to global and local levels of perceptual analysis in capuchin monkeys and if by doing so, their local dominance could be reversed. We manipulated attentional bias using a matching-to-sample (MTS) task where the proportion of trials requiring global and local processing varied between conditions. The monkeys were compared with humans tested with the same paradigm. Monkeys showed a local advantage in the local bias condition but a global advantage in the global bias condition. The role of attention in processing was confined to the local trials in a first phase of testing but extended to both local and global trials in the course of task practice. Humans exhibited an overall global dominance and an effect of attentional bias on the speed of processing of the global and local level of the stimuli. These results indicate a role for attention in the processing of hierarchical stimuli in monkeys and are discussed in relation to the extent to which they can explain the differences between capuchin monkeys and humans observed in this and other studies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

High throughput experiment approach to the oxidation of propene-to-propene oxide with transition-metal oxides as O-donors

The oxidation of propene-to-propene oxide (PO) has been achieved via oxygen-transfer from transition-metal oxides to the olefin. Under the operative conditions, the cleavage of the olefinic double bond is not observed. The only co-products are acetone (AC) and propinoaldehyde (PA), that can be considered as isomerisation products of propene oxide. The “parameter space” of the reaction has been investigated using a High Throughput Experiment (HTE) approach. However, it has been shown that the reaction yield and selectivity are sensitive to: temperature, time of the reaction, nature of the metal and its oxidation state and redox potential, lattice energy of the oxide, shape of the oxide (massive or supported), nature of the support, presence of the solvent, and the presence of CO₂. Several metal oxides have been investigated. In this paper, we report the general trend for the tested oxides and discuss in detail the behaviour of PdO_x and V₂O₅, either in the massive form or as supported oxides (on alumina or silica). The oxides have been monitored using UV–vis and XPS and the organic products have been identified and determined by GC–MS.     

Fatty acid and fat‐soluble antioxidant concentrations in milk from high‐ and low‐input conventional and organic systems: seasonal variation

BACKGROUND: Previous studies showed differences in fatty acid (FA) and antioxidant profiles between organic and conventional milk. However, they did not (a) investigate seasonal differences, (b) include non‐organic, low‐input systems or (c) compare individual carotenoids, stereoisomers of α‐tocopherol or isomers of conjugated linoleic acid. This survey‐based study compares milk from three production systems: (i) high‐input, conventional (10 farms); (ii) low‐input, organic (10 farms); and (iii) low‐input non‐organic (5 farms). Samples were taken during the outdoor grazing (78 samples) and indoor periods (31 samples). RESULTS: During the outdoor grazing period, on average, milk from the low‐input systems had lower saturated FAs, but higher mono‐ and polyunsaturated FA concentrations compared with milk from the high‐input system. Milk from both the low‐input organic and non‐organic systems had significantly higher concentrations of nutritionally desirable FAs and antioxidants—conjugated linoleic (60% and 99%, respectively) and α‐linolenic (39% and 31%, respectively) acids, α‐tocopherol (33% and 50%, respectively) and carotenoids (33% and 80%, respectively)—compared with milk from the high‐input system. Milk composition differed significantly between the two low‐input systems during the second half of the grazing period only; with milk from non‐organic cows being higher in antioxidants, and conjugated linoleic acid, and that from organic cows in α‐linolenic acid. In contrast, few significant differences in composition were detected between high‐input and low‐input organic systems when cows were housed. CONCLUSIONS: Milk composition is affected by production systems by mechanisms likely to be linked to the stage and length of the grazing period, and diet composition, which will influence subsequent processing, and sensory and potential nutritional qualities of the milk. Copyright © 2008 Society of Chemical Industry     

Analysis and Design of Distributed Key Distribution Centers

A Key Distribution Center of a network is a server who generates anddistributes secret keys to groups of users for secure communication. A Distributed Key Distribution Center is a set of servers that jointly realizes a Key Distribution Center. In this paper we describe in terms of information theory a model for Distributed Key Distribution Centers, and we present lower bounds holding in the model for the main resources needed to set up and manage a distributed center, i.e., memory storage, randomness, and bandwidth. Then we show that a previously proposed protocol which uses a bidimensional extension of Shamir’s secret sharing scheme meets the bounds and is, hence, optimal.     

Molecular recognition imaging using tuning fork-based transverse dynamic force microscopy

We demonstrate simultaneous transverse dynamic force microscopy and molecular recognition imaging using tuning forks as piezoelectric sensors. Tapered aluminum-coated glass fibers were chemically functionalized with biotin and anti-lysozyme molecules and attached to one of the prongs of a 32 kHz tuning fork. The lateral oscillation amplitude of the tuning fork was used as feedback signal for topographical imaging of avidin aggregates and lysozyme molecules on mica substrate. The phase difference between the excitation and detection signals of the tuning fork provided molecular recognition between avidin/biotin or lysozyme/anti-lysozyme. Aggregates of avidin and lysozyme molecules appeared as features with heights of 1–4 nm in the topographic images, consistent with single molecule atomic force microscopy imaging. Recognition events between avidin/biotin or lysozyme/anti-lysozyme were detected in the phase image at high signal-to-noise ratio with phase shifts of 1–2°. Because tapered glass fibers and shear-force microscopy based on tuning forks are commonly used for near-field scanning optical microscopy (NSOM), these results open the door to the exciting possibility of combining optical, topographic and biochemical recognition at the nanometer scale in a single measurement and in liquid conditions.