In recent years, the increase in the generation of waste (e.g., bones and skin) from the processing of fish-based food related to the increase in fish consumption and the accumulation of synthetic polymers in the environment are causing major environmental concerns. Hydroxyapatite (HA) extracted from the bones and collagen from the skin of fish processing residues can be combined with synthetic polymers to maximize the use of waste material derived from fish while simultaneously reducing the use of synthetic polymers. Hence, in this study, collagen and HA were extracted from the carcasses of Lophiosilurus alexandri, and the obtained materials were reused to prepare low-density polyethylene (LDPE) blends and composites. The integrity of the triple helix structure of collagen was confirmed by FTIR and DSC showing that there was no collagen denaturation during its extraction and sample processing. The results indicated that the material produced by the incorporation of collagen into LDPE compatibilized with polyethylene-graft-maleic anhydride exhibits good mechanical and surface properties for use as a support material for ornamental articles, among other applications.

RESUMO Esse estudo testou a utilização de marcadores externos em juvenis de Lophiosilurus alexandri, assim como o tamanho mínimo ideal do peixe para marcação. No experimento 1 foi avaliado a taxa de retenção e a influência do marcador sobre a sobrevivência e crescimento dos peixes divididos por tamanho nas classes: Pequeno, Médio e Grande. Após 90 dias, os peixes apresentaram 100% de sobrevivência e uma taxa de retenção mais elevada para os animais classificados como grandes. O segundo experimento avaliou a influência do marcador sobre os parâmetros hematológicos dos animais após 5, 10 e 30 dias da marcação. Neste experimento, foram observados valores mais elevados para o hematócrito no 30º dia para os animais marcados, enquanto nenhuma diferença foi observada para leucócitos, proteína plasmática, eritrócitos e volume corpuscular médio. Concluiu-se o que o marcador reduziu a taxa de crescimento dos animais menores, e que a taxa de retenção aumentou com o aumento do tamanho do animal. Dos parâmetros hematológicos avaliados, o marcador influenciou apenas no valor do hematócrito, o que mostra que o marcador pode ser usado sem considerável influência nos parâmetros hematológicos do L. alexandri.

ABSTRACT This study tested an external tag for juveniles of Lophiosilurus alexandri and measured the effects of tagging in different size classes of fishes. Experiment 1 evaluated the retention rate and influence of the tag on survival and growth of three hundred fishes divided Small, Medium and Large size classes. After 90 days of experiment the fishes had 100% survival and the tag had a higher retention rate for animals of the Large size class. Experiment 2 evaluated the tag’s influence on hematology parameters of forty-two fishes at 5, 10 and 30 days post-tagging. In this experiment both tagged and untagged animals experienced 9.4% mortality. The hematocrit was higher on the 30th day for tagged animals than for untagged animals. No difference was observed for leukocytes, plasma protein, erythrocytes and mean corpuscular volume. It was concluded from Experiment 1 that the tag reduced growth performance when applied to small sized juvenile L. alexandri, and that the tag retention rate increased with increasing animal size. Among the hematological parameters studied for juveniles on the Experiment 2 the tag only influenced the hematocrit parameters, which shows that the tag can be used without considerable influence on the hematological parameters of juvenile L. alexandri.

Medicinal and aromatic plants are commonly sold dried; however, it is necessary to understand the effects different drying methods have on these materials, to ensure their efficiency and quality. Ocimum gratissimum L., Lamiaceae, is an aromatic plant whose essential oil is stored in glandular trichomes. This study aimed to confirm the effects of different drying temperatures and methods of O. gratissimum leaves on trichome integrity and essential oil content. Leaves dried in a forced ventilation oven at 60ºC display damaged trichomes and a reduction in the essential oil content. The different drying methods (oven, dehumidification and air drying) were not identified to elicit changes in the essential oil content or damage to trichomes. All of the drying methods showed a reduction in fungal contamination in a logarithmic cycle.