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    A Comparative Study on Microstructure Properties of AZ91 Magnesium Alloy with Silicon Addition Using Ceramic Mold
    (Polish Acad Sciences Inst Physics, 2019) Goren, H. A.; Unal, M.; Koc, E.
    In this study, comparatively microstructure and hardness properties of AZ91 alloy with the addition of 1.95 wt% silicon were investigated by using ceramic mold. For this purpose, the alloys were provided to solidfy in different rates due to using that mold. Alloys cast into this mold showed rapid cooling behavior due to copper in the base, while cooling rate decreased on the top zone. The results showed that alpha+Mg main matrix phase is present in AZ91 structure, Mg-Al eutectic and Mg17Al12 intermetallic phases extending along grain boundaries were observed in the main matrix as well. As the cooling rate increases, the grain boundaries of Mg17Al12 intermetallic phases were increased. The Mg17Al12 phase at grain boundaries was partially fragmented with the addition of Si. Coarsen Mg2Si phases were also formed with the addition of 1.95 wt% silicon. The hardness values were increased with the increasing of cooling rate and the addition of silicon.
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    Efficiency of ascorbic acid against oxidative stress-induced dimethoate toxicity in fish, Capoeta capoeta [Guldenstaedt, 1773]
    (Triveni Enterprises, 2017) Yilmaz, M.; Kaya, I.; Koc, E.; Tanriverdl, E. A.; Kaya, M. M.; Ersan, Y.
    Aim: The main objective of the present study was to evaluate the effect of ascorbic acid against oxidative stress-induced by dimethoate in Capoeta capoeta. Methodology: The fish caught in Kars Creek were randomized in four equal groups and acclimatized in separate tanks. The fish were kept in tanks for 10 days as follows: Group I (control) was kept in normal water, Group II, Ill and IV were kept in separate tanks containing 2 mgrdimethoate and 2 mgr dimethoate plus 100 mgr' ascorbic acid and ascorbic acid. The level of total sialic acid, total antioxidant status and total oxidant status in fish serum were analyzed. Results: Total sialic acid level of Group III was found to be lower than the level of Group II (P< 0.05), there were no statistically important differences between these two groups in total antioxidant status and oxidant status. In gills, intensive cartilage degenerations and mononuclear cell infiltrations in group II and III were observed. It was found that toxic effects of dimethoate in group III decreased. Interpretation: Ascorbic acid in fish exposed to dimethoate reduced the level of total sialic acid and degenerations in lamellae of gills, it had no significant effect on the oxidative stress response. [GRAPHICS] .