ABSTRACT
RESUMO A concentração de óleos e graxas em amostras de águas contaminadas com resíduos oleosos pode ser determinada pelos procedimentos estabelecidos no Standard Methods for the Examination of Water and Wastewater. No entanto, sua aplicação nem sempre resulta em valores adequados ou níveis de precisão satisfatórios para atendimento de padrões normativos. Nesse sentido, este artigo apresenta uma proposta de ensaio para determinação da concentração de óleos minerais em águas provenientes de áreas pavimentadas, sujeitas ao derramamento de óleos e graxas. Tal método tem por base o método de partição gravimétrica (5520 B), estabelecido pelo Standard Methods. No novo procedimento, a etapa de separação entre o solvente de extração contendo os resíduos e o restante da fase aquosa foi substituída pela evaporação de toda a água da amostra, em estufa a 85ºC. Para avaliar a eficiência do método, foram preparadas amostras com concentrações conhecidas de óleo de 200, 100, 50, 25 e 15 mg.L-1 em água destilada e realizados ensaios de laboratório para determinação do teor de óleo, conforme tal procedimento. Os valores obtidos para as concentrações de óleo são bastante satisfatórios, apresentando comportamento linear em relação às concentrações de referência. Esse fato evidencia a confiabilidade do método proposto e sua aplicabilidade na determinação da concentração de óleos em amostras de águas contaminadas provenientes do escoamento superficial em pavimentos.
ABSTRACT Oil and grease concentration in water samples contaminated by oily residues can be determined by the procedures established in the Standard Methods for the Examination of Water and Wastewater. However, its application does not always result in adequate values or satisfactory accuracy levels in order to meet regulatory standards. In this sense, this paper presents a test-method proposal for determining mineral oil concentration in water samples from runoff of paved areas subject to oil and grease spillages. This method is based on the partition-gravimetric method (5520 B) established by the Standard Methods. In the new procedure, the separation between the extraction solvent containing residues and the aqueous phase remainder was replaced by the whole water sample evaporation in an oven at 85ºC. In order to assess the proposed method's efficiency, samples were prepared with known oil concentrations of 200, 100, 50, 25 and 15 mg.L-1, in distilled water and laboratory tests were performed to determine the oil content, according to the new procedure. The values obtained for the oil concentrations through the proposed procedure are quite satisfactory, presenting linear behavior in relation to the reference concentrations. This fact evidences the reliability of the new method and its applicability in determining the oil concentration in contaminated water samples from runoff in pavement surfaces.
ABSTRACT
Autogenous bone grafts have frequently been used in the treatment of bone defects; however, this procedure can cause clinical complications after surgery. Besides, the amount of available bone is sometimes insufficient. Therefore, synthetic biomaterials have been researched as an alternative to autogenous bone graft implants. The objective of this study was to evaluate the repair of bone defects treated with compact autogenous bone graft or porous calcium phosphate ceramics. Three defects 3 mm in diameter were produced in the skull of 21 rats. One the defects was produced in the frontal bone, which remained empty, while the others were produced in the right and left parietal bones, which were filled respectively with ceramics and autogenous bone graft. The animals were sacrificed 1, 2, 4, and 24 weeks after surgery and analyzed by light microscopy and radiography. In the twenty-fourth week, the defects filled with autogenous bone graft and ceramics had similar volumes of newly formed bone tissue. The ceramics offered favorable conditions to bone tissue growth. Thus, we concluded that the calcium phosphate ceramic implant proved to be effective in repairing defects produced in the skull of rats.
Subject(s)
Bone Regeneration , Bone Substitutes , Bone Transplantation , Calcium Phosphates , Craniotomy/methods , Animals , Ceramics , Male , Rats , Rats, Wistar , Skull/surgeryABSTRACT
It has been reported that excessive alcohol consumption can contribute to failures on the osteointegration process in the site of implantation. Hydroxyapatite blocks were implanted under the periosteum of the femur and skull of 40 rats divided into two groups of 20 animals, one of them received 25% ethanol diluted in water and the other did not. Bone formation close to the hydroxyapatite implant was observed in the femur of all animals 2 weeks after surgery, however the bone volume was lower in ethanol-treated animals. It was observed in the skulls of the ethanol-treated animals a delay in new bone formation process, as a lower bone volume, too. After 4 weeks of the implantation, just one ethanol-treated animal showed no new bone formation in the femur, while no bone formation was observed in the skulls of two other rats. On the 8th and 16th weeks, bone formation was observed in both femur and skull from both groups, although always with less volume in ethanol-treated rats. We concluded that ethanol consumption did not impair osteointegration of ceramic implants, but it might have reduced the osteogenic capacity of periosteal cells in the femur and parietal bone of the rats.
