155 resultados para GC-RICH


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O presente trabalho objetivou determinar o tempo mínimo necessário à realização do teste de germinação para sementes de B. brizantha cv. Marandu, o método de superação de dormência e a condição de temperatura que proporcionem a maior germinação no menor tempo. Numa primeira etapa, realizou-se o teste de germinação em trinta lotes de sementes, sob duas condições de temperaturas (15-35ºC e 20-35ºC), avaliadas em conjunto com três métodos para a superação de dormência (H2SO4, KNO3 e Controle), constituindo seis tratamentos. Realizaram-se contagens diárias da germinação para a determinação da data mais apropriada para o término do teste. Na segunda etapa, realizaram-se testes de germinação em oito lotes de diferentes níveis de vigor, utilizando-se os mesmos seis tratamentos e com encerramento do teste nas datas definidas na primeira etapa. Conclui-se que, para o teste de germinação de B. brizantha, a escarificação com H2SO4 e a temperatura de 20-35ºC são tratamentos que resultam na maior germinação em um menor tempo, possibilitando o encerramento do teste aos 11 dias após a semeadura.

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The styrene levels of polystyrene (PS) glasses from the most consumed brands of disposable glasses intended for water and coffee in Brazil were determined. A GC-FID method was developed and validated, showing good precision and accuracy. The method was successfully used to determine styrene in 11 PS glass brands. The styrene levels ranged from 1.68 to 43.69 mg/100 g glass, depending on the kind of polymer, thickness, and glass brand. It could be used to control the content of styrene in the polymer. The migration of styrene from the glasses into water and 20 % ethanol was not detected.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Objectives: To analyze the healing of autogenous onlay bone grafts in three different situations, focusing on the interface area.Material and methods: Sixteen rabbits underwent autogenous bone graft surgeries in the calvaria. The block bone grafts were positioned in three different situations: direct contact between bone graft and receptor bed, graft interposed by particulate bone, and graft interposed by platelet-rich plasma (PRP). After 7, 15, 30, and 60 days, the specimens were retrieved for histological and morphometric evaluation.Results: All groups healed uneventfully and presented incorporation of the grafts after 30 days. A slightly more evident new bone formation could be observed in the PRP group in the first analyzed period, and an earlier maturation of bone in the last period, although no statistically significant differences were achieved.Conclusion: the use of additional material between the bone graft and the receptor bed when using the onlay technique must be carefully considered, taking into account the size of the reconstruction and the cost/benefit relation. The addition of PRP in between autogenous bone blocks and the receptor bed did not confer significant benefit for the new bone formation and healing on the calvaria of bone of rabbits.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The purpose of this study was to analyze histologically the influence of platelet-rich plasma (PRP) coagulated with two different activators on bone healing in surgically created critical-size defects (CSD) in rat calvaria.Forty-eight rats were divided into three groups: C, PRP-C and PRP-T. An 8 mm diameter CSD was created in the calvarium of each animal. In group C, the defect was filled by a blood clot only. In groups PRP-C and PRP-T, the defect was filled with PRP activated with either calcium chloride or thromboplastin solution, respectively. Each group was divided into two subgroups (n = 8 per subgroup) and killed at either 4 or 12 weeks postoperatively. Histologic and histometric analyses were performed. The amount of new bone formed was calculated as a percentage of the total area of the original defect. Percentage data were transformed into arccosine for statistical analysis (analysis of variance, Tukey's post hoc test, p < 0.05).No defect completely regenerated with bone. Group PRP-C had a statistically greater amount of bone formation than groups C and PRP-T at both time points of analysis. No statistically significant differences were observed between groups C and PRP-T.It can be concluded that the type of activator used to initiate PRP clot formation influences its biological effect on bone healing in CSD in rat calvaria.

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AimThis study histologically analysed the effect of autogenous platelet-rich plasma (PRP), prepared according to a new semiautomatic system, on healing of autogenous bone (AB) grafts placed in surgically created critical-size defects (CSD) in rabbit calvaria.Material and MethodsSixty rabbits were divided into three groups: C, AB and AB/PRP. A CSD was created in the calvarium of each animal. In Group C (control), the defect was filled by blood clot only. In Group AB (autogenous bone graft), the defect was filled with particulate autogenous bone. In Group AB/PRP (autogenous bone graft with platelet-rich plasma), it was filled with particulate autogenous bone combined with PRP. All groups were divided into subgroups (n=10) and euthanized at 4 or 12 weeks post-operatively. Histometric and histologic analyses were performed. Data were statistically analysed (anova, t-test, p < 0.05).ResultsGroup C presented significantly less bone formation compared with Group AB and AB/PRP in both periods of analysis (p < 0.001). At 4 weeks, Group AB/PRP showed a statistically greater amount of bone formation than Group AB (64.44 +/- 15.0% versus 46.88 +/- 14.15%; p=0.0181). At 12 weeks, no statistically significant differences were observed between Groups AB and AB/PRP (75.0 +/- 8.11% versus 77.90 +/- 8.13%; p > 0.05). It is notable that the amount of new bone formation in Group AB/PRP at 4 weeks was similar to that of Group AB at 12 weeks (p > 0.05).ConclusionWithin its limitation, the present study has indicated that (i) AB and AB/PRP significantly improved bone formation and (ii) a beneficial effect of PRP was limited to an initial healing period of 4 weeks.

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Objective. The objective of this study was to histologically analyze the influence of the platelet-rich plasma (PRP) on bone healing in surgically created critical-size defects (CSD) in the calvaria of diabetic rats.Study design. A total of 20 diabetic rats were divided into 2 groups: C (control) and PRP. A 5-mm diameter CSD was created in the calvarium of each animal. In Group C, the defect was filled by blood clot only. In Group PRP, 0.35 mL of PRP was placed in the defects. All animals were humanely killed 30 days postoperatively. Histometric and histologic analyses were performed. Data were statistically analyzed (t test, P < .05).Results. No defect completely regenerated with bone. Group PRP had a statistically greater amount of bone formation than Group C (37.22% +/- 6.00% and 21.68% +/- 11.35%, respectively).Conclusion. PRP placed in the defects significantly enhanced bone healing in CSD in the calvaria of diabetic rats both qualitatively and quantitatively. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 72-78)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)