Alterations in the fat body cells of rhinocricus padbergi (Diplopoda) resulting from exposure to substrate containing sewage sludge

Abstract The final disposal of residues generated at sewage treatment plants (STPs) has become a major problem for cities, due to the increase in the amount of treated sewage. One of the alternatives for the residue, labeled sewage sludge, is its reuse in agriculture and in degraded soil. However, not all pathogens and metals present in it are eliminated during treatment. Diplopods have been used as bioindicators in ecotoxicological tests as they are constantly in close contact with the soil. Owing to this fact, the purpose of this study was to expose specimens of the diplopod Rhinocricus padbergi to substrate containing sewage sludge collected at STPs to analyze morphological alterations in their parietal and perivisceral fat body, where substances are stored. The exposures were held for 7, 15, or 90 days at different concentrations of sewage sludge (control, 1%, 10%, and 50%). The parietal fat body showed no alterations in any of the three exposure periods or concentrations. Alterations in the perivisceral fat body were observed for all exposure periods. According to the results, we suggest that the sludge used has toxic agents responsible for changing the animal's perivisceral fat body. © 2012 Microscopy Society of America.

PLA and Organoclays Nanocomposites: Degradation Process and Evaluation of ecotoxicity Using Allium cepa as Test Organism

In this study, nanocomposites of PLA and organoclays Cloisite 20A and Cloisite 30B were prepared by the melt intercalation method and the obtained samples were characterized by transmission electron microscopy (TEM). Since composting is an important proposal to the final disposal of biopolymers, the influence of clays on the hydrolytic degradation process of PLA was evaluated by visual analysis and monitoring of molecular weight after periods of 15 and 30 days of degradation in compost. After degradation of the materials in composting environment, the evaluation of cytotoxic, genotoxic and mutagenic effects of compost aqueous extract was carried out using a bioassay with Allium cepa as test organism. The TEM micrographs permitted the observation of different levels of dispersion, including exfoliated regions. In the evaluation of hydrolytic degradation it was noted that the presence of organoclays can decrease the rate of degradation possibly due to the barrier effect of clay layers and/or the higher degree of crystallinity in the nanocomposite samples. Nevertheless, even in the case of nanocomposites, the molecular weight reduction was significant, indicating that the composting process is favorable to the chain scission of PLA in studied materials. In the analysis performed by the bioassay using A. cepa as test organism, it was found that after degradation of the PLA and its nanocomposites the aqueous extract of compost samples induced a decreasing in the mitotic index and an increasing in the induction of chromosomal abnormalities. These results were statistically significant in relation to the negative control (distilled water). By comparing the results obtained for the nanocomposites in relative to pure polymer, there were no statistically significant differences. The types of the observed chromosomal aberrations indicated a possible genotoxic effect of the materials, which may be related to an aneugenic action of PLA degradation products. © 2013 Springer Science+Business Media New York.

Informe final del Octavo Período de Sesiones del Comité de Desarrollo y Cooperación del Caribe = Final report of the Eighth Session of the Caribbean Development and Co-operation Committee

Presenta la organizacion de la reunion, el resumen de los debates, conclusiones y recomendaciones sobre los temas: ejecucion del programa de trabajo del CDCC desde el 7o periodo de sesiones; proyecto de programa de trabajo para el bienio 1986-1987; accion sobre resoluciones aprobadas en el 6o y 7o periodo de sesiones del CDCC; resoluciones de CEPAL que tienen consecuencias para el CDCC; y admision de las Islas Virgenes Britanicas y las Islas Virgenes de Estados Unidos como miembros asociados del CDCC.

Informe del Noveno Período de Sesiones del Comité de Desarrollo y Cooperación del Caribe = Final report of the Ninth Session of the Caribbean Development and Co-operation Committee = Rapport de la Neuvième Session du Comité de Développement et de Coopération des Caraïbes

Presenta el resumen de las recomendaciones y decisiones tomadas en la reunion en lo que se refiere a la implementacion del programa de trabajo del CDCC para el periodo 1984-1985.

Informe final de la Reunión de Directores de Estadística de las Américas = Final report of the Meeting of Directors of Statistics of the Americas

Presenta el resumen de los debates de la reunión que tuvo como principales propósitos evaluar los avances logrados en actividades preparatorias de la Ronda de Censos del 90, absorción de tecnologías computacionales para el desarrollo estadístico de la región, cooperación técnica, capacitación y situación de las estadísticas sociales.

Final report of the UNESCO

Presenta el informe final del Seminario sobre metodologías para evaluar las infraestructuras de información y experiencias relacionadas en América Latina y el Caribe; contiene las recomendaciones generales y una lista de documentos emanados de dicho Seminario.

Informe final de la Reunión de Expertos sobre Problemas de Facilitación y el Fortalecimiento de las Instituciones de Transporte = Final report of the Meeting of Experts on Facilitation Problems and the Strengthening of Transport Institutions

Informe final de la Reunion convocada para identificar los principales problemas de facilitacion que se confrontan en cada ambito, fijar prioridades y sugerir medidas que puedan contribuir a la superacion de dichos problemas por parte de los paises, y prestar asistencia a la Secretaria para establecer un programa de accion mas permanente y estable en la materia.

Informe final de la Reunión Regional de Evaluación de INFOPLAN = Final report of the Regional Assessment Meeting on INFOPLAN

Incluye Bibliografía

Urban management in medium-sized cities: final report of the case study Port-of-Spain, Trinidad and Tobago

Includes bibliography

Final report of the DOCPAL first phase: CELADE

Includes bibliography

Final report of the phase five of the Latin American Instituten for Economic and Social Planning (ILPES)

Incluye Bibliografía