This work aimed to develop biodegradable composites formed from corn starch-based films and cellulose extracted from pineapple crown residue. Fibers obtained from the crowns underwent alkaline treatment, followed by bleaching. Cellulose was characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). These analyses verified that the process was effective in isolating cellulose fibers. The biocomposites were then produced via casting and with cellulose of different concentrations (5%, 10%, 15%). These biocomposites were less soluble in water than the pure starch film, and the film with 15% cellulose had lower water vapor permeability rate (WVPR) compared to pure starch film. In terms of the thermal characterization, there were no significant variations in the melting and gelatinization temperatures of the films. When analyzing the mechanical properties, it was seen that the Young’s modulus of the biocomposites increased in relation to the starch film, in which the composite with a 15% increase of 377.76%. Regarding the tensile strength, there were no differences between preferences, probably due to the dispersion of the fibers.
Progress in the field of biodegradable materials has been significantly accelerated in recent years, driven by the search for sustainable substitutes for fossil-derived resources. This study investigates the formulation of biodegradable films composed of polyvinyl alcohol (PVA) and nanocellulose extracted from rice husk. The rice husk underwent alkaline treatment and bleaching for cellulose extraction, followed by sulfuric acid hydrolysis to obtain nanocellulose. The cellulose and nanocellulose were characterized through Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). Films of pure PVA and those reinforced with 1 wt. % of nanocellulose were prepared using the solvent casting method. The evaluations showed that the modulus of elasticity and tensile strength of the PVA/nanocellulose films were increased by 295.45% and 29.6%, respectively, compared to the pure PVA film. The PVA/nanocellulose film exhibited the lowest solubility and water vapor permeability. Optical Microscopy confirmed a flawless surface for the nanocellulose-reinforced film, while the cellulose- and rice husk-reinforced films displayed irregularities. In the biodegradability assessment, the nanocellulose-reinforced film was the only one that withstood the experimental conditions. The results highlight the effectiveness of nanocellulose in enhancing PVA properties, making these films promising for sustainable packaging applications.
One of the main barriers to restoration is the arrival of diaspores in degraded areas. However, this process can be hampered in open areas without trees in the landscape. For that, artificial perches are used to attract and provide a landing area for avian seed dispersers, to enhance seed rain. Our objective was to evaluate the effect of the distance of artificial perches in relation to a forest fragment on the diversity and composition of seed rain in an agricultural fallow area, including alien invasive plant species. We also aimed to record and characterize the bird species that potentially act as seed dispersers. Thus, we used artificial perches at three different distances from a forest fragment (5, 25, and 50 m). Four seed traps were arranged under the perches at each distance, and four control seed traps were interspersed with these and distanced at 7.5 m. Furthermore, we placed four seed traps inside the forest fragment at 5 m from the edge. We also carried out 80 h of focal observation of the avifauna that used artificial perches. A total of 24 655 seeds were sampled across all treatments. There was a significant difference in seed abundance and richness between artificial perches, control seed traps, and forest seed traps. Seed deposition increased with distance from the forest fragment (50, 25, and 5 m). An ordination procedure indicated the formation of three plant seed communities, with the forest community being most distinct. The invasive exotic species Pittosporum undulatum (Australian cheesewood) was the third most abundant in the seed rain. We observed 24 bird species from 12 families using artificial perches. The Tyrannidae family was the most represented. We showed that artificial perches are efficient structures for attracting birds, increasing the richness and abundance of seed species. Artificial perches at 25 and 50 m were more efficient possibly due to the provision of greater visibility for birds. Therefore, artificial perches are efficient in increasing seed rain in the fallow area but should be used with caution in landscapes with the presence of alien species. These findings contribute to increasing knowledge about overcoming the first barrier to ecological restoration, which is the arrival of diaspores in degraded areas, and showing the importance of birds in this process.
We describe new records of Trichothraupis melanops in five municipalities of Rio Grande do Sul, Brazil. The birds were detected in sporadic expeditions in the Serra do Sudeste and Campanha Gaúcha regions by direct visualization and vocal recognition. One of these records, next to the border with Uruguay, is the southernmost known location for the species in Brazil. This record expands the geographic range of the species in Brazil south by 170 km. We believe that these occurrences are seasonal displacements and do not represent a colonization front with resident populations.
6 December 2024 in Southern Forests: a Journal of Forest Science