The effect of preliminary processing and period of storage on the quality of frozen Boletus edulis (Bull: Fr.) mushrooms

This paper investigates the effect on the quality of frozen Boletus edulis (Bull: Fr.) mushrooms of blanching or soaking and blanching in aqueous solutions containing combinations of added substances safe for human consumption, or period of frozen storage. During 12 months of storage, sensory evaluations, instrumental colour measurements and chemical analyses of the frozen products were carried out every four months. Based on the results of the sensory evaluation, a maximum storage period of four months was set for the frozen product obtained from unblanched mushrooms. Frozen products having undergone preliminary processing retained good sensory quality for up to 12 months. Soaking, blanching and freezing resulted in the appearance of colours, such as yellow, honey and pink–violet. As a result of freezing, decreases in the contents of thiamine, riboflavin and vitamin C were noted. Blanching in water, as a method of pre-processing, was sufficient for maintaining acceptable sensory quality.     

Linked multi-component mobile robots: Modeling,simulation and control

The Linked Multi-Component Robotic Systems (L-MCRS) consists of a group of mobile robots carrying a passive uni-dimensional object (a hose or a wire). It is a recently identified unexplored and unexploited category of multi-robot systems. In this paper we report the first effort on the modeling, control and visual servoing of L-MCRS. Modeling has been tackled from geometrical and dynamical points of view. The passive element is modeled by splines, and the dynamical modeling is achieved by the appropriate extension of Geometrically Exact Dynamic Splines (GEDS). The system’s modeling allows realistic simulation, which can be used as a test bed for the evaluation of control strategies. In this paper we evaluate two such control strategies: a baseline global controller, and a fuzzy local controller based on the observation of the hose segment between two robots. Finally, we have performed physical experiments on a team of robots carrying a wire under a visual servoing scheme that provides the perceptual information about the hose for the fuzzy local controller. Visual servoing robust image segmentation is grounded in the Dichromatic Reflection Model (DRM).     

Citral Induces Auxin and Ethylene-Mediated Malformations and Arrests Cell Division in Arabidopsis thaliana Roots

Citral is a linear monoterpene which is present, as a volatile component, in the essential oil of several different aromatic plants. Previous studies have demonstrated the ability of citral to alter the mitotic microtubules of plant cells, especially at low concentrations. The changes to the microtubules may be due to the compound acting directly on the treated root and coleoptile cells or to indirect action through certain phytohormones. This study, performed in Arabidopsis thaliana, analysed the short-term effects of citral on the auxin content and mitotic cells, and the long-term effects of these alterations on root development and ethylene levels. The results of this study show that citral alters auxin content and cell division and has a strong long-term disorganising effect on cell ultra-structure in A. thaliana seedlings. Its effects on cell division, the thickening of the cell wall, the reduction in intercellular communication, and the absence of root hairs confirm that citral is a strong phytotoxic compound, which has persistent effects on root development.     

Some Notes on Declarative Specification of Semantic Data Integration Task in a Peer-to-peer Agent System

In the paper, a problem of semantic integration of XML data in a peer-to-peer agent system is analysed upon a channel theory. In the system, each agent manages its local data, and communication and cooperation actions, executed by the agents, consist of asking and answering queries. The abstract notions of classification and infomorphism are used to clarify the roles of queries and mappings in the system. The query reformulation task is modelled by the composition of an appropriate infomorphisms. In order to specify classifications and infomorphisms executable Prolog-like clauses and generelized terms are used. Logic programming systems are chosen because of the logical variables and partial data representation, effective techniques of data unification and partial evaluation, suitable built-in terms and procedures, and automated reasoning.     

Influence of confinement on conformational entropy of a polymer chain and structure of polymer-nanoparticles complexes

Behaviour of a polymer chain in the presence of fixed obstacles has been studied by the static Monte Carlo simulations. A modified self-avoiding walk on a cubic lattice has been used to model the polymer in an athermal solution. The statistical counting method has been applied to calculate the conformational entropy of the chain, assumed to be grafted to an obstacle. Different chain lengths and obstacle curvatures have been examined. Some implications of the confinement induced changes in the conformational entropy of polymer chains to the structure of complexes composed of long polymer chains and nanoparticles are discussed.     

Thermal characterization of screen printed conductive pastes for RFID antennas

Thermal resistance is an essential aspect of electronic circuits designing. It leads to unexpected changes in electronic components during their work. In this study, new materials for screen printed RFID tag's antennas were characterized in terms of their resistance to thermal exposure. Polymer materials containing silver flakes, silver nanopowder, carbon nanotubes or conductive polymer PEDOT:PSS were elaborated and used for antenna printing on flexible materials. In order to verify their long term susceptibility to damages caused by the changing environmental conditions, the temperature cycling test was used in three different temperature ranges: +65 °C, −12 °C, −40 °C/+85 °C (3 h in each temp., dwell time 1 h). The highest durability to thermal exposure exhibited the paste with carbon nanotubes dispersed in poly(methyl methacrylate) PMMA and the lowest one – the paste with conductive polymer PEDOT:PSS.     

Student Assessment of a Problem-Based Learning Experiment in Civil Engineering Education

This paper describes an experiment with problem-based learning (PBL), an instructional methodology used in response to the challenges posed by today’s professional education. Contrary to the conventional model that places an application problem after concepts or topics have been introduced, PBL uses the problem to initiate learning. Besides promoting the construction of knowledge, it may also contribute to the development of some skills and attitudes deemed important for engineers’ professional practice. This research, of a qualitative nature, intended to investigate how students evaluate this methodology and its potential to attain the educational goals set for the course. In order to answer the research question, the methodology was implemented in the civil engineering curriculum of a Brazilian public university. The results herein presented, deriving mainly from classroom observations and an end-of-course questionnaire, show that most of the students evaluate the methodology positively. Even considering the short duration of the course and its small number of credits, it may also have promoted the development of some skills and attitudes besides knowledge acquisition.