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Öğe Effect of garlic oil on erythrocyte membrane phospholipid fractions in hypercholesterolaemic dogs(LIPPINCOTT WILLIAMS & WILKINS, 1997) Keskin, E; Durgun, Z; Kocabatmaz, M; Tras, B; Eryavuz, A; Donmez, NWe studied the effects of a cholesterol diet alone and of a cholesterol diet plus garlic oil on erythrocyte membrane phospholipid fractions in 10 adult mongrel dogs. The animals were fed the control diet plus 0.5% cholesterol for 6 weeks and the control diet containing 5% cholesterol plus garlic oil at 20 mg kg(-1) body weight daily for the last 3 weeks of the experiment. Feeding with the cholesterol-rich diet resulted in significant (p < 0.05) increases in erythrocyte membrane lipids. The administration of garlic oil not only prevented the increases but also reduced the levels of phospholipid and cholesterol, though not significantly. Although phospholipid (PL) fractions showed fluctuations with the cholesterol feeding and garlic oil administration, there was no significant difference between the sampling times. In conclusion, further studies are necessary on the effect of garlic on the membrane PL fractions because of the importance of PL in all aspects of membrane physiology from anion transport to regulation of cell structure.Öğe An evaluation of surface hardness, roughness and wear of restorative composites, porcelain, and enamel following abrasion by enamel(TRANS TECH PUBLICATIONS LTD, 2004) Unlu, N; Donmez, N; Sengun, A; Ozer, FThis study was performed to evaluate wear, surface hardness and roughness characteristics of light cured restorative composites, porcelain and enamel when opposed by human enamel. Five composite resins (3MSilux, ClearfilAP-X, 3MFiltek Z250, Pekalite, SureFil), one ceramic (VitadurAlpha) and enamel were selected as experimental materials. The antagonist abrasives were made by using buccal enamel of anterior teeth. Ten rectangular specimens were prepared for each material. The at the beginning of the study, the mean weight, roughness and hardness values of specimens were obtained. Then the specimens were opposed by human enamel and subjected to 20.000 sliding cycles in a prototype wear machine. Surface characteristics and final weights of each materials were recorded and compared to the values obtained at the beginning. Statistically significant differences were found among the hardness and roughness of materials (p<0.05). After wear procedure, surface hardness of all materials increased. There was not any significant difference among the wear values of materials and enamel.Öğe Ultrastructural correlates of in vivo/in vitro bond degradation in self-etch adhesives(SAGE PUBLICATIONS INC, 2005) Donmez, N; Belli, S; Pashley, DH; Tay, FRThe morphologic correlates of bond degradation in self-etching primers have not been fully elucidated. We hypothesized that there is no difference between the mechanism of degradation of self-etching primers in vivo and in vitro. Class I cavities prepared in vivo in 24 caries-free human molars were bonded with Clearfil SE Bond or Clearfil Protect Bond, and restored with resin composites. Eight teeth were extracted after 24 hrs, and the rest after 1 yr. The same protocol was repeated in vitro with extracted molars. Degradation of resin-dentin bonds was assessed by microtensile bond testing and TEM of interfaces after tracer immersion. Both in vivo and in vitro bond strengths decreased with time for SE Bond but not for Protect Bond, with more pronounced water treeing observed in the former adhesive under both aging conditions. There is no difference between the mechanism of degradation of self-etch adhesives in vivo or in vitro.