Experimental determination of thermal conductivity of apple and potato at different moisture contents

Thermal conductivity of apple and potato samples was measured by means of a specifically designed apparatus based on Fitch's method. The thermal conductivity was determined at various moisture contents at the sample mean temperature of 30 °C. As expected the conductivity decreases with the decrease in moisture content. Thermal conductivity data were correlated with moisture content using a straight line.     

HLA_ACTOR_REPAST: An approach to distributing RePast models for high-performance simulations

RePast is a popular agent toolkit with proven capabilities to fulfil the modelling challenges of large multi-agent systems (MASs). The toolkit, though, is normally used on a standalone workstation and therefore its practical use can be constrained (in space and time) by the limited available computing resources. This paper proposes an original approach – HLA_ACTOR_REPAST – aimed to distributing RePast models for high-performance simulation of complex scalable models. Novel in HLA_ACTOR_REPAST is an exploitation of a lean actor infrastructure implemented in Java. Actors bring to RePast agents such features as migration, location-transparent naming, efficient communications, and a control-centric framework. Actors can be orchestrated by an in-the-large custom control structure which is in charge of ensuring the necessary message causality constraints. Distribution and time management concerns depend on the IEEE standard HLA middleware. The paper first discusses details of the software engineering process underlying the development of HLA_ACTOR_REPAST. The mapping techniques, assisted by Java text annotations and aspect-oriented programming, try to minimize “code intrusions” in the original model and favour model transparency. The paper then furnishes some experimental data which witness the good performance results achieved by applying HLA_ACTOR_REPAST to a distributed version of a classic MAS benchmark model.     

Rheological studies with spherically shaped thin liquid films

The present work shows the first experimental and theoretical results for investigations on the rheology of liquid films. The experiments are planned to be performed under microgravity conditions. This environment will allow forming films of different thickness, which is impossible under ground conditions due to drainage. Then the films are forced to harmonic oscillations of the film area so that the film elasticity can be measured as a function of frequency. The presented theoretical model demonstrates the main relationships to be solved under corresponding boundary conditions     

Seasonal variations of susceptibility to oxidative stress in Adamussium colbecki,a key bioindicator species for the Antarctic marine environment

The area of free radical biology is of increasing interest for marine organisms since the enhanced formation of reactive oxygen species (ROS) is a common pathway of toxicity induced by stressful environmental conditions. In polar environments responses of the antioxidant system could be useful as an early detection biomarkers of unforeseen effects of human activities which are progressively increasing in these remote areas. However, the characterization of antioxidant defences in appropriate sentinel species is of particular value also in terms of a possible adaptation to this extreme environment. The scallop, Adamussium colbecki, is a key species for monitoring the Antarctic environment and, besides single antioxidants, the total oxyradical scavenging capacity (TOSC) assay has been recently used for quantifying the overall ability of this organism to neutralize peroxyl radicals (ROO*), hydroxyl radicals (*OH) and peroxynitrite (HOONO). The aim of this work was to obtain a better characterization of these biological responses which can indicate the occurrence of biological disturbance; in this study the total oxyradical scavenging capacity was further analyzed to assess the presence of seasonal fluctuations in the susceptibility to oxidative stress in this species. The capability to neutralize peroxyl radicals and hydroxyl radicals increased at the end of December, while resistance towards peroxynitrite did not show any significant variations during the Antarctic summer. These results suggest the occurrence of metabolic changes which mainly influence intracellular formation of ROO* and *OH, with more limited effects on HOONO. Despite the limited time window analyzed, as a typical constraint in Antarctic research at Terra Nova Bay, an increased resistance to these specific oxyradicals might be related to the period of highest feeding activity, or to other intrinsic factors in the animals' physiology such as the phase of reproductive cycle.     

Exergy analysis of the recuperative auto thermal reforming (R-ATR) and recuperative reforming (R-REF) power cycles with CO2 removal

Two relatively innovative gas turbine (GT) based power cycles with high CO₂ removal potential have been proposed and discussed in terms of exergy analysis. Fuel decarbonisation is applied by the means of auto thermal reforming (R-ATR) and simple reforming (R-REF), in order to convert the primary natural gas into a highly H₂ and CO₂ concentrated fuel. Thus, CO₂ is captured with amine chemical absorption into a specific unit and, finally, the decarbonised fuel is sent to the GT combustion chamber. No bottoming steam cycle is included, which should promote the size flexibility of the powerplant. The heat content of GT exhausts is employed partially to sustain the endothermic reforming reactions and partially for cycle recuperation. Moreover, the possibility of steam blade cooling has been investigated.The efficiency is optimised at low pressure ratios (7–10) in the steam cooled R-ATR, whereas higher values have been found in air cooled version (16–17). Generally, the R-ATR solution shows higher efficiency levels, mainly due to the reduced combustion chamber and CO₂ capture exergy destruction and higher cycle recuperation degree.The exergy analysis showed a relatively limited influence of combustion chamber losses on the primary fuel exergy input (20–23%). The relative loss of CO₂ removal unit is limited as well (5–7%) when compared with values of semi-closed GT configurations. The exergy destruction of R-ATR and R-REF CO₂ removal sections is greatly reduced if steam blade cooling is adopted. Generally, all the proposed cycles showed satisfactory values of efficiency (43–46% under optimised conditions) taking into account that they do not involve combined power plants.     

Crystallization of 2D Hybrid Organic–Inorganic Perovskites Templated by Conductive Substrates

2D hybrid organic–inorganic perovskites are valued in optoelectronic applications for their tunable bandgap and excellent moisture and irradiation stability. These properties stem from both the chemical composition and crystallinity of the layer formed. Defects in the lattice, impurities, and crystal grain boundaries generally introduce trap states and surface energy pinning, limiting the ultimate performance of the perovskite; hence, an in-depth understanding of the crystallization process is indispensable. Here, a kinetic and thermodynamic study of 2D perovskite layer crystallization on transparent conductive substrates are provided—fluorine-doped tin oxide and graphene. Due to markedly different surface structure and chemistry, the two substrates interact differently with the perovskite layer. A time-resolved grazing-incidence wide-angle X-ray scattering (GIWAXS) is used to monitor the crystallization on the two substrates. Molecular dynamics simulations are employed to explain the experimental data and to rationalize the perovskite layer formation. The findings assist substrate selection based on the required film morphology, revealing the structural dynamics during the crystallization process, thus helping to tackle the technological challenges of structure formation of 2D perovskites for optoelectronic devices.     

Development of virtual data acquisition systems based on multimedia internetworking

This paper proposes a novel approach centered on multimedia internetworking for the development of Distributed Virtual Instruments (DVI). Multimedia internetworking refers to network infrastructures, protocols, models, applications and techniques being currently deployed over the Internet to support multimedia applications, e.g., videoconferencing, video-on-demand, shared workspaces. It is applied to broaden the concept of virtual instrument and enable new measurement patterns leveraging efficiency and interactivity. A DVI is a virtual instrument split into possibly multiple and independent parts, sender and receiver, which are linked by real-time continuous media and control streams. Senders and receivers are built by using open, composable and modular components based on a time sensitive actor framework and glued by multimedia middleware. A prototype is described to demonstrate the potential and the benefits of the proposed approach.     

On the analysis of heterogeneous fluids with jumps in the viscosity using a discontinuous pressure field

Heterogeneous incompressible fluid flows with jumps in the viscous properties are solved with the particle finite element method using continuous and discontinuous pressure fields. We show the importance of using discontinuous pressure fields to avoid errors in the incompressibility condition near the interface.     

Effects of Pre- and Postharvest Chitosan Treatments to Control Storage Grey Mold of Table Grapes

ABSTRACT: The effectiveness of pre- and postharvest treatments with chitosan (0.1, 0.5, and 1.0%) to control Botrytis cinerea on table grapes was investigated. In postharvest treatments, small bunches dipped in chitosan solutions and inoculated with the pathogen showed a reduction of incidence, severity, and nesting of grey mold, in comparison with the control. Single berries artificially wounded, treated with the polymer, and inoculated with B. cinerea showed a reduced percentage of infected berries and lesion dia. Higher chitosan concentrations demonstrated greater decay reduction. All preharvest treatments significantly reduced the incidence of grey mold, as compared to the control. Table grapes treated with 1.0% chitosan showed a significant increase of phenylalanine ammonia-lyase (PAL) activity. Consequently, besides a direct activity against B. cinerea , chitosan produces other effects contributing to reduce decay.