Tanned leather of the paiche Arapaima gigas Schinz, 1822 (Arapaimidae) with extracts of vegetable origin to replace chromium salts

Enhancement in antimicrobial efficacy and biodegradation of natural rubber latex through graphene oxide/nickel oxide nanoparticles

This work aims to fabricate antibacterial natural rubber latex composites by introducing different ratios of graphene oxide (GO) and nickel oxide (NiO) nanoparticles. The nanocomposites were prepared using latex mixing and a two-roll mill process, followed by molding with a heating hydraulic press. Detailed analyses were conducted to evaluate the rheological, chemical, physical, thermal, mechanical, and electrical performance of the composites. Fourier transform infrared spectroscopy (FTIR) was employed to analyze the interaction among different components, while the surface morphology was examined through the field emission scanning electron microscopy (FESEM) technique. The composites with a loading ratio of 1:2 of GO to NiO (optimized concentration) exhibited the highest tensile strength (24.9 MPa) and tear strength (47.4 N/ mm) among all the tested samples. In addition, the composites demonstrated notable antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. The thermal stability of the composites was observed up to 315 °C, and their electrical resistivity lies in the insulating range across a temperature span of 25 °C to 50 °C. The research uncovers critical insights into advancing composite materials suitable for diverse applications, featuring inherent antibacterial attributes, robust mechanical properties, resilience to solvent, UV shielding properties, and controlled electrical resistivity capabilities.

Characterization and Strength Quality of the Oryctolagus cuniculus Leather Compared to Oreochromis niloticus Leather

This study aimed to compare the resistance of the Oryctolagus cuniculus L. (rabbit) and Oreochromis niloticus L. (Nile tilapia) skins, as well as to observe the design of the flower of these skins and the morphology of the dermis. Tilapia and rabbit skins were placed inside the same equipment (tannery machine) for the chromium salt tanning process. The flower design of the fish leather distinguishes it from the rabbit leather, the latter being constituted by the opening of the hair follicles and pores, while the fish leather is constituted by the presence of protective lamellae and insertion of the scales. The dermis of rabbit skin consists of thick bundles of collagen fibers arranged in all directions, which differs from the morphology observed in the dermis of fish skin. However, in the Nile tilapia skin dermis, overlapping and parallel layers of longitudinal collagen fiber bundles are observed, these layers are interspersed with fiber bundles crossing the sking surface (transversely), tying the fibers together and providing greater strength, which can be proven by the strength test. The fish leathers, despite having less thickness (1.0 mm), demonstrated significantly greater tensile strength (13.52 ± 1.86 N mm^-2) and tear strength (53.85 ± 6.66 N mm^-2) than rabbit leathers, that is, (8.98 ± 2.67 N mm^-2) and (24.25 ± 4.34 N mm^-2). However, rabbit leather demonstrated higher elasticity (109.97 ± 13.52%) compared to Nile tilapia leather (78.97 ± 8.40%). It can be concluded that although the rabbit leather is thicker due to the histological architecture of the dermis (thick bundles of collagen fibers arranged in all directions with no pattern of organization of collagen fibers), it shows less resistance than Nile tilapia leather, which demonstrates an organization of overlapping and parallel layers and intercalating collagen fiber bundles transversally to the surface, functioning as tendons for the swimming process. It is recommended to use a piece of fabric (lining) together with the fleshy side of the rabbit leather, to increase resistance when used in clothing and footwear, as these products require greater tensile strength. Thus, it minimizes this restriction for the use of rabbit leather in the aforementioned purposes.