Optical transmission as a fast and non‐destructive tool for determination of ethylene‐co‐vinyl acetate curing state in photovoltaic modules

Poly(ethylene‐co‐vinyl acetate) (EVA) is the primary polymer used for encapsulation of photovoltaic (PV) modules. Its degree of cross‐linking (gel content) is taken as a major quality reference. The EVA gel content is normally measured by Soxhlet extraction and more recently also by Differential Scanning Calorimetry (DSC). The DSC method is proven here to be fast and effective but is, as the Soxhlet extraction method, destructive to the PV module. With the aim of developing a fast and non‐destructive method to determine the gel content, a number of analytical techniques are presented. The most promising method is ultraviolet/visible/near‐infrared (UV/Vis/NIR) optical transmission. The measured diffuse transmission reflects the EVA crystallite size, which is related to the EVA gel content. This opens the possibility to apply an in‐line analysis of every PV module immediately after the lamination step and could significantly contribute to the process quality control that is needed in future high‐throughput production lines of PV modules. Copyright © 2011 John Wiley & Sons, Ltd.     

Nano Design of Alumina Supported Monometallic Catalysts: A Promising Way to Improve the Selective Hydrogenation of Poly-Unsaturated Hydrocarbons

In the field of catalysis by metals, a new insight for the nanodesign of supported heterogeneous catalysts is the tailoring of metallic nanoparticles. In this work, well-faceted monometallic nanoparticles (Pd, Pt, Ni) exposing mostly the {111} crystallographic facet are obtained in aqueous solution and are deposited on an alumina support. The involved mechanisms of nanoparticles formation are determined and are evidenced to be different as a function of the nature of the metal. In the case of palladium the mechanism consists in an oriented attachment of palladium nanoparticles leading to the energetically most favourable stacking of nanoparticles, at the origin of the early differentiation of the nanoparticles shapes and of the formation of the well-faceted palladium nanoparticles. In the case of platinum, the mechanism seems to be a combination of aggregation of already reduced nuclei and direct reduction depending on the experimental conditions. In the case of the less reductible metal, nickel, well-faceted nanoparticles are not obtained during the synthesis and only a thermal activation under hydrogen can engender their formation. The impact of the {111} crystallographic facet for platinum and nickel is very important and induces a drastic increase of selectivity towards olefins formation with a selectivity close to the one of a palladium catalyst which is the most selective metal for the selective hydrogenation of poly-unsaturated hydrocarbons.     

Development and Characterization of Phytosterol-Enriched Oil Microcapsules for Foodstuff Application

Phytosterols are lipophilic compounds contained in plants and have several biological activities. The use of phytosterols in food fortification is hampered due to their high melting temperature, chalky taste, and low solubility in an aqueous system. Also, phytosterols are easily oxidized and are poorly absorbed by the human body. Formulation engineering coupled with microencapsulation could be used to overcome these problems. The aim of this study was to investigate the feasibility of encapsulating soybean oil enriched with phytosterols by spray-drying using ternary mixtures of health-promoting ingredients, whey protein isolate (WPI), inulin, and chitosan as carrier agents. The effect of different formulations and spray-drying conditions on the microencapsules properties, encapsulation efficiency, surface oil content, and oxidation stability were studied. It was found that spherical WPI-inulin-chitosan phytosterol-enriched soybean oil microcapsules with an average size below 50 μm could be produced with good encapsulation efficiency (85%), acceptable level of surface oil (11%), and water activity (0.2–0.4) that meet industrial requirements. However, the microcapsules showed very low oxidation stability with peroxide values reaching 101.7 meq O₂/kg of oil just after production, and further investigations and optimization are required before any industrial application of this encapsulated system.     

Some Remarks on the Equivalence between 2D and 3D Classical Snakes and Geodesic Active Contours

Recently, Caselles et al. have shown the equivalence between a classical snake problem of Kass et al. and a geodesic active contour model. The PDE derived from the geodesic problem gives an evolution equation for active contours which is very powerfull for image segmentation since changes of topology are allowed using the level set implementation. However in Caselles' paper the equivalence with classical snake is only shown for 2D images and 1D curves, by using concepts of Hamiltonian theory which have no meanings for active surfaces. This paper propose to examine the notion of equivalence and to revisite Caselles et al. arguments. Then a notion equivalence is introduced and shown for classical snakes and geodesic active contours in the 2D (active contour) and 3D (active surface) case.     

Gremlin-1 and BMP-4 Overexpressed in Osteoarthritis Drive an Osteochondral-Remodeling Program in Osteoblasts and Hypertrophic Chondrocytes

Osteoarthritis (OA) is a whole joint disease characterized by an important remodeling of the osteochondral junction. It includes cartilage mineralization due to chondrocyte hypertrophic differentiation and bone sclerosis. Here, we investigated whether gremlin-1 (Grem-1) and its BMP partners could be involved in the remodeling events of the osteochondral junction in OA. We found that Grem-1, BMP-2, and BMP-4 immunostaining was detected in chondrocytes from the deep layer of cartilage and in subchondral bone of knee OA patients, and was positively correlated with cartilage damage. ELISA assays showed that bone released more Grem-1 and BMP-4 than cartilage, which released more BMP-2. In vitro experiments evidenced that compression stimulated the expression and the release of Grem-1 and BMP-4 by osteoblasts. Grem-1 was also overexpressed during the prehypertrophic to hypertrophic differentiation of murine articular chondrocytes. Recombinant Grem-1 stimulated Mmp-3 and Mmp-13 expression in murine chondrocytes and osteoblasts, whereas recombinant BMP-4 stimulated the expression of genes associated with angiogenesis (Angptl4 and osteoclastogenesis (Rankl and Ccl2). In conclusion, Grem-1 and BMP-4, whose expression at the osteochondral junction increased with OA progression, may favor the pathological remodeling of the osteochondral junction by inducing a catabolic and tissue remodeling program in hypertrophic chondrocytes and osteoblasts.     

A Level Set Model for Image Classification

We present a supervised classification model based on a variational approach. This model is devoted to find an optimal partition composed of homogeneous classes with regular interfaces. The originality of the proposed approach concerns the definition of a partition by the use of level sets. Each set of regions and boundaries associated to a class is defined by a unique level set function. We use as many level sets as different classes and all these level sets are moving together thanks to forces which interact in order to get an optimal partition. We show how these forces can be defined through the minimization of a unique fonctional. The coupled Partial Differential Equations (PDE) related to the minimization of the functional are considered through a dynamical scheme. Given an initial interface set (zero level set), the different terms of the PDE's are governing the motion of interfaces such that, at convergence, we get an optimal partition as defined above. Each interface is guided by internal forces (regularity of the interface), and external ones (data term, no vacuum, no regions overlapping). Several experiments were conducted on both synthetic and real images.     

Bulk synthesis of carbon nanostructures: Hollow stacked-cone-helices by chemical vapor deposition

Bulk synthesis of hollow carbon stacked-cone-helices of diameter from 10 nm to 0.5 μm is reported. The fibres’ walls are made up of parallel stacked-cone-like structures with an inter-cone distance from 3.38 to 3.5 Å. Apex angles observed are in the range from 30° to 110°, suggesting that the carbon nanofibres are constructed by a single graphene sheet which forms a helical structure instead of a stacked cone or open stacked cup structure. A new 3-D construction of the stacked-cone-helix is presented. Our results show that metal Pd catalyst plays a key role in obtaining carbon products with cone-helix structure and high yield (200%). These novel fibres could be used as nano-wire templates, micro-spray, and field emitters.     

A taxonomy of task-based parallel programming technologies for high-performance computing

Task-based programming models for shared memory—such as Cilk Plus and OpenMP 3—are well established and documented. However, with the increase in parallel, many-core, and heterogeneous systems, a number of research-driven projects have developed more diversified task-based support, employing various programming and runtime features. Unfortunately, despite the fact that dozens of different task-based systems exist today and are actively used for parallel and high-performance computing (HPC), no comprehensive overview or classification of task-based technologies for HPC exists. In this paper, we provide an initial task-focused taxonomy for HPC technologies, which covers both programming interfaces and runtime mechanisms. We demonstrate the usefulness of our taxonomy by classifying state-of-the-art task-based environments in use today.     

Location and orientation of panel on the screen as a structural visual element to highlight text displayed

Searching for information on the internet has become a daily activity. It is considered to be a complex cognitive activity that involves visual attention. Many studies have demonstrated that users’ information search are affected both by the spatial configuration of words and the elements displayed on the screen: elements that are used to structure web pages. One of these elements, the web panel, contains information. Web panel is a rectangular area with a colored background that was used to highlighting content presented in this specific rectangular area. Our general hypothesis was that the presence of a panel on a web page would affect the structure of a word display, as a result, information search accuracy. We carried out an experiment in which we manipulated the presence vs. the absence of a panel, as well as its orientation on the screen (vertical vs. horizontal). Twenty participants were asked to answer questions while their eye movements were recorded. Results showed that the presence of a panel resulted in reduced accuracy and shorter response times. Panel orientation affected scanpaths, especially when they were orientated vertically. We discuss these findings and suggest ways in which this research could be developed further in future.