Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and wheat straw fibre composites: thermal, mechanical properties and biodegradation behaviour

The thermal and mechanical behaviour of a biotechnological polyester (poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) reinforced with wheat straw fibres has been investigated. In order to improve chemico-physical interactions between the components, the reinforcing agent has been previously submitted to a treatment with high temperature steam leading to fibres richer in cellulose and more reactive. The addition of straw fibres has been found to increase the rate of PHBV crystallisation, while it does not affect the crystallinity content. Furthermore, the comparison of the mechanical properties has shown that the composites exhibit higher Young moduli and lower values of both the stress (_B) and strain (_B) to break than the neat matrix of PHBV. The biodegradability in different environments by means of short and long term tests has been studied. It has been observed that the presence of straw does not affect biodegradation rate evaluated in liquid environment and in long term soil burial tests. In the composting simulation test the rate of biodegradation is reduced for composites with more than 10% of straw content. The morphology of the composites has also been investigated and correlated to the biodegradation process.     

New technologies for relaxation: The role of presence.

In recent years, several publications have appeared on virtual reality (VR) therapy in the treatment of anxiety disorders. However, a limited number of these studies targeted stress management and relaxation. To evaluate the efficacy of VR as a support tool in the relaxation process, this study compared its efficacy with two other media (DVD and audiotape). The goals of the experiment were to test the efficacy of each condition in increasing relaxation and reducing anxiety, and whether the sense of presence-the feeling of being inside the media content-correlated with the efficacy of the treatment. Results suggested the importance of the sense of presence as a mediating variable between the media experience and the efficacy of the protocol. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prediction of air and steam leak rate through cracked reinforced concrete panels

The leak rate prediction of air and steam through a cracked concrete wall is an extremely important issue in assessing the safety of a nuclear reactor containment building. Such a problem requires a multidisciplinary approach involving both the non-linear analysis of the structure, and the thermodynamics aspects related to the flow of a gas through a conduit. In the present paper, some of the available leak rate evaluation formulae are reviewed, and an application to the prediction of the leak rate of either dry air or air+steam mixture through a cracked concrete panel is presented. Finally, in order to validate the numerical procedure herein adopted and to give some indication on the relative merit of the different leak rate formulae considered, the results of the numerical application are compared against leak rate values measured during an experimental test carried out at the ISMES laboratory.     

Backward solution of PV nodes in radial distribution networks

In this paper an iterative backward methodology to solve radial distribution networks with fixed voltage (PV) nodes and with constant power loads or mixed loads (with at least one component with constant power) is proposed. The method developed, although deriving conceptually from the backward/forward (b/f) methodology, presents only the backward phase in which all the network variables are evaluated.     

Evaluation of E2PROM data retention by field acceleration

This work presents an improved theoretical analysis of the physical mechanisms leading to charge loss from the floating gate of electrically erasable PROMs (E²PROMs). The analysis is applied to a simplified model of a FLOTOX cell in order to evaluate data retention characteristics using the applied field as an accelerating factor. A set of experimental results (obtained on virgin as well as on aged cells) is presented and degradation of data retention due to cell aging is examined.     

A new vector quantization technique for performance evaluation infrequency hopping mobile radio systems

A new technique based on vector quantization (VQ) is proposed for interfacing the link-level and the system level analysis of frequency hopping (FH) mobile systems. The method represents an original solution to overcome the problem that the time scales adopted within the two analysis levels are usually different, thus discouraging a direct link between them. The VQ technique is applied, as a test case, to the study of a typical FH-GSM mobile environment. The corresponding results show excellent correlation with those achievable by means of a much more time consuming, as well as often infeasible, direct approach