Search Results (9)

This research assessed novel, eco-friendly intumescent coatings utilizing cork and recycled glass as sustainable alternatives to synthetic fire retardants, aiming to reduce environmental impact while maintaining robust fire performance. Coatings underwent up to 600 h of UV light exposure for durability assessment, followed by chemo-physical characterization. Fire exposure tests evaluated in-situ char formation and foaming. All functionalized coatings exhibited suitable intumescent behavior, forming protective char layers even after extensive UV aging. Microscopic analysis showed good additive integration, while FTIR spectroscopy revealed UV-induced chemical changes. Fire resistance tests confirmed the superior performance of functionalized coatings over the commercial reference. The AP-IC system demonstrated the best intumescence, achieving significantly lower maximum temperatures (e.g., 167.3 °C for AP-IC-600) and heating rates. Crucially, the sustainable RG-IC and CK-IC batches showed promising intumescent properties, even improving with UV exposure. Notably, the foamed cross-sectional area of the aged RG-IC samples doubled compared to their unaged counterparts, reaching a maximum temperature of 166.9 °C. These findings highlight the potential of eco-friendly hybrid coatings to enhance fire safety, particularly in critical sectors like naval engineering, aligning with circular economy principles and the growing demand for sustainable, high-performance materials. Full article

This paper presents the initial prototypes of solutions designed using plastic caps, seeking acoustic applications for both airborne sound insulation and the acoustic conditioning of rooms. Plastic caps are a waste product from the packaging sector and they constitute a major waste problem, given that, if they are not attached to the packaging, they get lost during the recycling cycle and end up in landfill. Finding an application for this waste that can provide acoustic improvements is a sustainable alternative. This paper shows the results of airborne sound insulation measurements obtained in a scaled transmission chamber and sound absorption measurements obtained in a scaled reverberation chamber for different combinations of single and double plastic caps and combinations with thin sheets of sustainable materials, such as jute weaving, textile waste, hemp felt and cork board. Tests have shown that obtaining sound reduction index values of up to 20 dB is possible with plastic cap configurations, or even up to 30 dB is possible at some frequencies with combinations of caps and certain eco-materials. With regard to the sound absorption coefficient tests, close to unity absorption values have been achieved with the appropriate configuration at frequencies that can also be selected. The results indicate that these panels can be eco-solutions for airborne sound insulation as lightweight elements, or they can be used for the conditioning of rooms, tailoring the sound absorption maximums to the desired frequencies. Full article

The bonding quality is a key property for wood-based composites. Determination of the bonding quality of sandwich panels with veneer faces and <50 mm thick cork core is not covered either by the EN 314-1, which refers to plywood, nor by its Annex B, which refers to insulating cores with a thickness of at least 50 mm. This technical note assesses the possibility of using the prescriptions of Annex B of EN 314-1 to test the bonding quality (shear strength) of the concerned panels. For this purpose, sandwich panels were realized by bonding fromager (Ceiba pentandra) veneers to a 5 mm thick core, and their bonding quality was tested. Two types of panels were realized, based on the adhesive used (glue spread 340 g/m² for double glue lines): urea–formaldehyde (UF) and urea–melamine–formaldehyde (UMF); the panels were pressed at 103 °C for 8 min at a nominal pressure of 0.4 MPa. Pre-treatments were dry-conditioned at 20 °C/65% relative humidity until attainment of the equilibrium moisture content, and immersed in water: cold water for UF panels (5.1.1 of EN 314-2) and boiling water for UMF panels (5.1.2 of EN 314-2). The effect of pre-treatment was statistically significant, with shear resistance reductions of 56% and 43% in UF and UMF panels, respectively. Based on this first investigation (2 panels × 10 specimens per panel = 40 specimens), the test method can be considered suitable for providing reliable results. This study constitutes a useful reference to test the bonding quality of sandwich panels with veneer faces and thin cork cores. Full article

Energy performances of an innovative Temporary Housing Unit (THU), made of natural materials and developed for the Mediterranean area, were determined. Cork panels limit winter transmission losses, whereas bio-PCMs were applied to reduce cooling needs properly. Assuming a split system for air-conditioning purposes, simulations in EnergyPlus allowed for identifying the optimal configuration that minimizes the annual electric demand. Bio-PCM melting temperatures, locations inside the external walls and the PCM quantities were varied. An ideal melting temperature of 23 °C was identified, whereas a double PCM layer uniformly distributed in the external walls is recommended, mainly for the limitation of the cooling demands. Negligible differences in electric requirements have been observed between the continuous and the scheduled functioning of the split system. A PV generator installed on the available roof surface allows for covering the electric demands satisfactorily. Experimental tests carried out in a climatic chamber have allowed for determining the dynamic thermal performance of the optimized panel by considering variable external conditions. Results show how the considered PCM in summer is able to delay and attenuate the indoor air temperature peaks considerably, confirming the crucial role of bio-PCM to reduce cooling demands, in line with the simulation results. Full article

The Tlemcen region is characterized by very diverse and steep areas exposed to gravity hazards, especially in high and medium mountain areas. Tlemcen National Park was chosen for this study, the main objective of which is to map fragile areas in close relation to reduced vegetation cover due to land-use changes and forest fires. Multi-source data were used to monitor land use/land cover (LULC)patterns in the study area between 1987 and 2017. The methodology is based on an object-oriented classification of the Landsat images, using the K nearest neighbor method for mapping the major LULC classes at the national park level. The results show that LULC is constantly changing in the study area. In 1987, the landscape was made up of (16.5%) oak forests (holm oak, cork oak, zean oak) and Aleppo pine, which then deteriorated following repeated fires in the nineties to barely represent 7.22% of the surface in 1995, followed by a fast forest reclamation, with the forest area doubling in 10 years (13.46% of the area in 2005), and a near stabilization of the forest cover in 2017 with 14.68% of the area. These mutations are mainly due to fluctuations in anthropogenic action. Despite past declines and disturbances, the current forested area in the Tlemcen area represents significant forest capital classified as a national park to be protected and developed. Full article

The building envelope is critical to reducing operational energy in residential buildings. Under moderate climates, as in South-Western Europe (Portugal), thermal operational energy may be substantially reduced with an adequate building envelope selection at the design stage; therefore, it is crucial to assess the trade-offs between operational and embodied impacts. In this work, the environmental influence of building envelope construction with varying thermal performance were assessed for a South-Western European house under two operational patterns using life-cycle assessment (LCA) methodology. Five insulation thickness levels (0–12 cm), four total ventilation levels (0.3–1.2 ac/h), three exterior wall alternatives (double brick, concrete, and wood walls), and six insulation materials were studied. Insulation thickness tipping-points were identified for alternative operational patterns and wall envelopes, considering six environmental impact categories. Life-cycle results show that, under a South-Western European climate, the embodied impacts represent twice the operational impact of a new Portuguese house. Insulation played an important role. However, increasing it beyond the tipping-point is counterproductive. Lowering ventilation levels and adopting wood walls reduced the house life-cycle impacts. Cork was the insulation material with the lowest impact. Thus, under a moderate climate, priority should be given to using LCA to select envelope solutions. Full article

Cellular materials have been used in many applications such as insulation, packaging, and protective gear. Expanded polystyrene has been widely used as energy-absorbing liner in helmets due to its excellent cost-benefit relation. This synthetic material can absorb reasonable amounts of energy via permanent deformation. However, in real-world accidents, helmets may be subjected to multi-impact scenarios. Additionally, oil-derived plastic is presently a major source of societal concern regarding pollution and waste. As a sustainable alternative, cork is a natural cellular material with great crashworthiness properties and it has the remarkable capacity to recover after compression, due to its viscoelastic behavior, which is a desired characteristic in multi-impact applications. Therefore, the main goal is to analyze the applicability of agglomerated cork as padding material in safety helmets. First, a finite element model of a motorcycle helmet available on the market was developed to assess its safety performance and to establish a direct comparison between expanded polystyrene and cork agglomerates as liners. Secondly, a new helmet model with a generic geometry was developed to assess the applicability of agglomerated cork as liner for different types of helmets, based on the head injury risk predictions by the finite element head model, YEt Another Head Model (YEAHM), developed by the authors. Several versions of helmet liners were created by varying its thickness and removing sections of material. In other words, this generic helmet was optimized by carrying out a parametric study, and by comparing its performance under double impacts. The results from these tests indicate that agglomerated cork liners are an excellent alternative to the synthetic ones. Thus, agglomerated cork can be employed in protective gear, improving its overall performance and capacity to withstand multi-impacts. Full article

(+)-epi-Epoformin (1), is a fungal cyclohexene epoxide isolated together with diplopimarane and sphaeropsidins A and C, a nor-ent-pimarane and two pimaranes, from the culture filtrates of Diplodia quercivora, a fungal pathogen for cork oak in Sardinia, Italy. Compound 1 possesses a plethora of biological activities, including antifungal, zootoxic and phytotoxic activity. The last activity and the peculiar structural feature of 1 suggested to carry out a structure activity relationship study, preparing eight key hemisynthetic derivatives and the phytotoxicity was assayed. The complete spectroscopic characterization and the activity in the etiolated wheat coleoptile bioassay of all the compounds is reported. Most of the compounds inhibited growth and some of them had comparable or higher activity than the natural product and the reference herbicide Logran. As regards the structure-activity relationship, the carbonyl proved to be essential for their activity of 1, as well as the conjugated double bond, while the epoxide could be altered with no significant loss. Full article

Most viruses are known for the ability to cause symptomatic diseases in humans and other animals. The discovery of Acanthamoeba polyphaga mimivirus and other giant amoebal viruses revealed a considerable and previously unknown area of uncharacterized viral particles. Giant viruses have been isolated from various environmental samples collected from very distant geographic places, revealing a ubiquitous distribution. Their morphological and genomic features are fundamental elements for classifying them. Herein, we report the isolation and draft genome of Cedratvirus, a new amoebal giant virus isolated in Acanthamoeba castellanii, from an Algerian environmental sample. The viral particles are ovoid-shaped, resembling Pithovirus sibericum, but differing notably in the presence of two corks at each extremity of the virion. The draft genome of Cedratvirus—589,068 base pairs in length—is a close relative of the two previously described pithoviruses, sharing 104 and 113 genes with P. sibericum and Pithovirus massiliensis genomes, respectively. Interestingly, analysis of these viruses’ core genome reveals that only 21% of Cedratvirus genes are involved in best reciprocal hits with the two pithoviruses. Phylogeny reconstructions and comparative genomics indicate that Cedratvirus is most closely related to pithoviruses, and questions their membership in an enlarged putative Pithoviridae family. Full article