Search

Despite natural fibers gaining significant attention in recent decades, their limited performance and poor durability under humid environments cannot allow them to fully replace their synthetic counterparts as reinforcement for structural composites. In such a context, this paper aims to investigate how exposure to a humid/dry cycle affects the mechanical response of epoxy laminates reinforced with flax and glass fibers. In particular, the main goal is to assess the performance evolution of a glass–flax hybridized stacking sequence in comparison with the full glass and flax fiber reinforced composites. To this end, the investigated composites were first exposed to salt-fog for 15 or 30 days and then to dry conditions (i.e., 50% R.H. and 23 °C) for up to 21 days. The presence of glass fibers in the stacking sequence significantly stabilizes the mechanical performance of composites during the humid/dry cycle. Indeed, hybridization of inner flax laminae with outer glass ones, acting as a protective shield, hinders the composite degradation due to the humid phase also promoting performance recovery during the dry phase. Hence, this work showed that a tailored hybridization of natural fibers with glass fibers represents a suitable approach to extend the service-life of natural fiber reinforced composites exposed to discontinuous humid conditions, thus allowing their employment in practical indoor and outdoor applications. Finally, a simplified theoretical pseudo-second-order model that aimed to forecast the performance recovery shown by composites was proposed and experimentally validated, highlighting good agreement with the experimental data.

This report analyzes Rousseau’s Discourse on the Sciences and Arts and the polemics Rousseau wrote in defense of that work, paying special attention to his rhetoric. In supplementing an interpretation of the First Discourse with Rousseau’s polemics, several of the paradoxes of the work are resolved. I argue that the central paradox of the work, whether Rousseau is for or against science, can be resolved: Rousseau is ultimately in favor of science but highly critical of popularized science. Since virtue is the only sound basis of civil society, and science corrupts virtue, Rousseau speaks out against science. But the life dedicated science is the source of the highest flourishing for those who are capable of it. Hence, he concludes the discourse by praising a certain kind of science that is compatible with virtue. His complex position reveals a keen awareness of the distinction between the few and the many—a distinction of the utmost importance for politics, according to Rousseau. Moreover, I analyze Rousseau’s distinct understanding of civic health and corruption and the causes of corruption. Rousseau does not argue that the sciences and arts are the original or sole causes of corruption; they can only come into being in an already corrupt society. However, they do tend to reinforce corruption and make the return to virtue all but impossible. I conclude with an analysis of what can be done in practice according to Rousseau given his bleak analysis of contemporary politics.

Nowadays sustainability is one of the main concept in building construction, both considering energy saving buildings and life cycle assessment of building materials. According to these considerations, in this work the use of recycled and waste materials to produce a binder and the use of a natural fiber as reinforcement are investigated to obtain a sustainable mortar. Particularly, lime is obtained by kilning waste marble slurry from marbles quarries in western Sicily; pozzolanic aggregate is obtained by grinding glass powder from urban waste collection; natural fibers come from a widespread grass: Ampelodesmos Mauritanicus also known as diss. Scanning electron microscopy and helium picnometry have been performed to characterize diss fibers. Samples with different fibers volume percentage have been prepared and subjected to three-point bending and compression tests, in order to verify the modification of resistance related to the presence of fibers; moreover, capillary uptake and thermal conductivity have been evaluated.The results show a great influence of fibers’ percentage on both mechanical and environmental properties of mortars, resulting in lowering of mechanical resistance and thermal conductivity., Academic Journal of Civil Engineering, Vol 37 No 2 (2019): Special Issue - ICBBM 2019

Cork is a unique material, characterized by small closed cell structures, high insulating properties, very low density, high fire resistance and a very good durability after simple thermal treatment. The main use of cork in the production of stopper and insulating panels obtained with cork grains and a polymeric resin. Usually cork grains used in panel production have a grainsize around 1-2 mm. In this work cork grains have been used as aggregates for natural hydraulic lime mortars by reducing grainsize distribution. Cork grainsize has been reduced by means of a knife mill and divided in three different distributions, i.e. 1, 0.5 and 0.25mm. Mortars have been prepared according to NHL to cork to natural sand volume ratio equal to 2:3:2. Three point bending and compression tests showed that reducing cork grainsize leads to a slight increase in mechanical performance. On the other hand thermal conductivity showed to be independent from cork grainsize. Scanning electron microscope investigation was also performed to better understand these results., Academic Journal of Civil Engineering, Vol 37 No 2 (2019): Special Issue - ICBBM 2019

I benefici derivanti dalla pratica dell'esercizio fisico sono stati ampiamente documentati. Tuttavia, l’eccessivo ricorso alla attività fisica può condurre alla messa in atto di pattern compulsivi di allenamento che possono evolversi in una vera e propria patologia: l' exercise addiction. Studi recenti suggeriscono l'espansione di due fenomeni: il doping amatoriale e l'abuso di integratori per lo sport. Sono stati somministrati 686 test. I partecipanti allo studio sono stati scelti tra studenti di scuola media superiore, studenti universitari e frequentatori di ambienti sportivi. Il 42,5% degli intervistati dichiara di assumere sostanze per migliorare le prestazioni sportive e quindi di doparsi. Il 30,23% assume integratori. Una percentuale compresa tra il 35 e l'88,35 % dichiara di non conoscere le sostanze proposte.Il 15,8% dei rispondenti è a “rischio” di exercise addiction, il 71,7% è classificato come “sintomatico”. E' stata infine indagata quale possibile correlazione potesse esserci tra le variabili in esame. La statistica test X2 evidenzia che non vi è alcuna associazione , in altre parole non sembra esserci relazione tra il rischio di dipendenza dall' esercizio fisico e l'assunzione di sostanze. L'analisi dei dati raccolti suggerisce invece che vi sia un'espansione del fenomeno del doping in ambiente amatoriale e che vi sia una scriteriata e incongrua assunzione di integratori per lo sport. La presente ricerca suggerisce che occorre compiere interventi immediati sia a livello di informazione che di prevenzione , in cui al farmacista sia affidato un ruolo di primo piano.