Metamodels in Europe: Languages, Tools, and Applications

Editor's note:This article provides an overview of current efforts in Europe for using metamodeling in the integrated development of critical systems such as automotive electronics. It distinguishes between lightweight versus heavyweight approaches, surveys a number of related current European projects, and gives details about the Speeds project to illustrate the role of metamodeling-driven system engineering.—Sandeep Shukla, Virginia Tech     

Influence on cheese proteolysis and sensory characteristics of non-starter lactobacilli strains with probiotic potential

The contribution to cheese proteolysis and sensory profile of four potentially probiotic non-starter lactobacilli strains was assessed in two different models: soft and semi-hard cheeses. All the strains were able to grow in both types of cheese, where they maintained high levels during ripening. Overall, adjunct cultures of Lactobacillus rhamnosus showed the strongest influence in peptidolysis, which was verified by changes in peptide profiles and increase of free amino acids concentration. Nevertheless, some cheeses treated with L. rhamnosus also showed post-acidification during ripening and decreased sensory characteristics compared to controls. Cheeses with adjunct cultures of Lactobacillus casei I90 and Lactobacillus plantarum I91 exhibited, in general, an intermediate level of peptidolysis between control and L. rhamnosus-added cheeses; their sensory characteristics were preserved or improved, and they did not show any defects. Adjunct cultures showed similar trends in both models, confirming L. casei I90 and L. plantarum I91 as the most performing adjunct cultures for cheese-making among the strains.     

A methodology for evaluating environmental impacts of railway freight transportation policies

Railway freight transportation presents a degree of complexity which frequently makes impossible to model it with sufficient precision. Currently, energetic and environmental impacts of freight transportation are usually modelled following average data, which do not reflect the characteristics of specific lines. These models allow qualitative approximations which may be used as criteria for designing high-level transportation policies: road–train modal shift, regional energetic planning or environmental policies.     

Effect of sea water on biochemical properties of fruit of tomato (Lycopersicon esculentum Mill.) genotypes differing for ethylene production

BACKGROUND: Three near‐isogenic lines of cv. Gimar differing in ethylene production were used to evaluate the influence of salinity on fruit quality. Plants were grown in rockwool culture and were irrigated with nutrient solution with electrical conductivities (ECs) of 3 and 8 mS cm^?1, which corresponded to 0 and 10% of sea water. For fruits picked at ‘red‐turning’ and ‘red‐ripe’ stages physico‐chemical parameters, ethylene, ascorbate and organic acid content, and cell reductive power were analysed. RESULTS: The same response was observed in all genotypes: the higher salinity growth solution increased dry matter content, total soluble solids (TSS) and titratable acidity but reduced crop yield. Ascorbic acid and also organic acid contents showed a greater accumulation with ripening in the mutant genotypes: this might be due to a slowing of ripening. Our data confirm the lack of any relationship between the larger accumulation of TSS and ethylene production in the fruits of salt‐treated plants. CONCLUSION: These findings suggest that although salinity (10% sea water) reduces fruit yield, it does not have a negative effect on quality. So, it seems possible that controlled use of diluted sea water, combined with suitable tomato genotypes might represent a valid alternative to fresh irrigation water. Copyright © 2007 Society of Chemical Industry     

Atomistic fracture: QFM vs. MD

In this work we discuss the paradigmatic case of brittle fracture in defective elastic-plastic cubic silicon carbide, by a combination of Quantized Fracture Mechanics and Molecular Dynamics atomistic simulations. Different defect sizes and shapes, or crack-inclusion interactions are considered. Our results show that Quantized Fracture Mechanics is able to effectively incorporate the main lattice-related features, while Molecular Dynamics atomistic simulations do provide the most basic level of understanding of mechanical behaviour of brittle materials.     

Physiological basis of sensitivity to enzymatic browning in ‘lettuce’, ‘escarole’ and ‘rocket salad’ when stored as fresh-cut products

In fresh-cut leafy vegetables, the operation of cutting may stimulate enzymatic browning, with important commercial consequences. In this work, a number of physiological and biochemical parameters, including the activities of key enzymes involved in the metabolism of phenols (such as PAL, PPO, and PODs) and ascorbic acid (ASA), were measured in three species: lettuce (Lactuca sativa var. capitata L.), escarole (Cichorium indivia var. latifolium) and rocket salad (Eruca sativa), upon cold storage as fresh cuts. The first two species are quite sensitive to leaf browning, which does not affect rocket salad.     

Luminescence of heat-treated silicon-based polymers: promising materials for LED applications

A new strategy to obtain transparent, thermally stable, and formable photoluminescent materials for LED applications is presented. Starting from commercially available silicon-based polymers, luminescence properties are developed by means of simple heat treatment. Solid polymethylsilsesquioxane MK (Wacker-Besil^®PMS MK) and liquid poly(ureamethylvinyl)silazane Ceraset (Kion Ceraset^® PUVMS) were thermally treated between 200 and 700 °C for 2 h under Ar atmosphere. Photoluminescence properties were observed in all the samples. The structural rearrangements during thermal annealing were effective in order to red-shift the emission spectra of the untreated polymers to the visible range. The formation of dangling bonds and carbon sp², associated with the annealing procedure and confirmed by means of Electron Paramagnetic Resonance (EPR) spectroscopy and solid state Magic Angle Spinning NMR (MAS-NMR) contribute to the red-shift of the photoluminescence emissions of the polymers. After heat treatment at low temperatures (200, 300, and 400 °C), both the polymers show fluorescence in the UV range. While the polysiloxane reveals white luminescence after annealing at 500 and 600 °C, the polysilazane heat-treated at 500 °C exhibits emission in the blue-green range and is transparent. At higher temperatures the presence of free carbon counteracts the luminescence properties.