Multi-walled carbon nanotubes functionalized with pyrene-PEG via π-π interactions: toxicological assessment in zebrafish embryos.

Multi-walled carbon nanotubes (MWCNT) have many promising biological applications, even though functionalization is needed for better biocompatibility. Functionalization of MWCNT with polyethylene glycol (PEG) is a promising and widely studied approach, but the best PEGylation method is still under investigation. In this work, we have tested the biological implications of MWCNT functionalized via π-stacking with pyrene-PEG (MWCNT-Pyr-PEG) in zebrafish embryos. As Pyr toxicity is well documented and represents a major concern for the safety of the proposed approach, we have also tested the effects of the exposure to the isolated conjugate (Pyr-PEG). The resulting suspensions were stable in saline medium and well dispersed. Zebrafish embryos at 24 h post-fertilization (hpf) were dechorionated and randomly assigned to seven experimental groups (n = 50 per group): control, MWCNT-Pyr-PEG at 0.2, 2.0, and 20.0 mg l-1, and Pyr-PEG at the same concentrations, and exposures were performed in 96-well plates. Specimens were observed for heart rate, malformations, body length, mortality, traveled distance, and number of new movements. Heart rate was reduced in embryos exposed to any tested concentration of MWCNT-Pyr-PEG, while this effect was observed with Pyr-PEG from 2 mg l-1. The highest concentration of MWCNT-Pyr-PEG also led to increased occurrence of malformations, shortened body length and reduced traveled distance. The functionalization approach shows promise due to the stability in saline media, even though toxic effects were observed in the highest tested concentrations, being the MWCNT the main actors underlying these outcomes.

Composição gravimétrica e peso específico dos resíduos sólidos urbanos em Jaú (SP) / Gravimetric composition and specific weight of urban solid waste in Jaú (SP)

Este trabalho apresenta os resultados da avaliação dos resíduos sólidos domiciliares no município de Jaú (SP) por meio de amostragens realizadas em 2001 e 2010. Foram determinados a quantidade per capita, o peso específico e a composição gravimétrica dos resíduos sólidos urbanos gerados nos Jardins América e Ameriquinha em 2010, comparando os resultados obtidos aos da amostragem realizada em 2001 com a mesma metodologia. Constatou-se que a geração de resíduos aumentou 34,9%, enquanto a população cresceu 29,6% no período, levando a um incremento de 4,0% na geração per capita de resíduos, que passou de 618 g. hab-1.dia-1 para 643 g. hab-1.dia-1. Dos resíduos gerados no município, aproximadamente 50% são de matéria orgânica, 25% de rejeitos e 25% de materiais recicláveis, percentuais que pouco se alteraram nas duas amostragens. Entretanto, os resíduos do tipo "plástico mole", entre os recicláveis, foram aqueles cuja geração teve o maior aumento percentual (59%) na avaliação.

This paper presents the results of the evaluation of urban solid waste in Jaú (SP) by means of samplings accomplished in 2001 and 2010. There were determined the quantity per capita, the specific weight and the gravimetric composition of waste generated in the neighborhoods Jardim América and Ameriquinha in 2010, comparing the results with a sample taken in 2001 with the same methodology. It was found that waste generation increased by 34.9% while the population grew 29.6%, leading to an increase of 4.0% per capita in generation of waste, which increased from 618 g. inhab-1.day-1 to 643 g. inhab-1.day-1. Waste generated in the county about is 50% organic matter, 25% wasting and 25% recyclable materials, percentages that have changed little in two samples. However, the soft plastic, among the recyclable material, was the one that had the largest increase (59%) in the evaluation.