Search

Aluminum casting alloys are widely used in especially automotive, aerospace, and other industrial applications due to providing desired mechanical characteristics and their high specific strength properties. Along with the increase of application areas, the importance of recycling in aluminum alloys is also increasing. The amount of energy required for producing primary ingots is about ten times the amount of energy required for the production of recycled ingots. The large energy savings achieved by using the recycled ingots results in a significant reduction in the amount of greenhouse gas released to nature compared to primary ingot production. Production can be made by adding a certain amount of recycled ingot to the primary ingot so that the desired mechanical properties remain within the boundary conditions. In this study, by using the A356 alloy and chips with five different quantities (100% primary ingots, 30% recycled ingots + 70% primary ingots, 50% recycled ingots + 50% primary ingots, 70% recycled ingots + 30% primary ingots, 100% recycled ingots), the effect on mechanical properties has been examined and the maximum amount of chips that can be used in production has been determined. T6 heat treatment was applied to the samples obtained by the gravity casting method and the mechanical properties were compared depending on the amount of chips. Besides, microstructural examinations were carried out with optical microscopy techniques. As a result, it has been observed that while producing from primary ingots, adding 30% recycled ingot to the alloy composition improves the mechanical properties of the alloy such as yield strength and tensile strength to a certain extent. However, generally a downward pattern was observed with increasing recycled ingot amount. [ABSTRACT FROM AUTHOR]

Concentrations of persistent organic pollutants (POPs) were quantified in river water and sediment, as well as in the liver and muscle tissues of Cyprinus carpio that were sampled four times in a year at three stations in the Büyük Menderes River (BMR). Potential biomarkers of possible cellular molecular damage, namely lipid peroxidation (LPO) degradation products, protein carbonyls (PCO) and DNA repair product 8-hydroxy-2'-deoxyguanosine (8-OHdG), were analysed. All the targeted pollutants were measurable both in biotic and abiotic samples. Interestingly, the results suggested that there was recent organochlorine pesticide (OCP) input into the river water in the first two sampling periods in all stations in contrast to prohibition, while input of polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs) was not detected. Liver POP concentrations were higher than in muscle, as expected, and were found to decrease from the first to the fourth sampling period in all stations, except PBDEs. Levels of LPO degradation products in the liver and in muscle tissues decreased from the first to the fourth sampling period. This suggests that these markers reflect the lipid damage in respective tissues due to the tissue burden of targeted POPs. Protein carbonyls were the highest in the first sampling period, followed by a dramatic decrease in the second, and then a gradual increase towards the fourth sampling period in all stations. 8-OHdG levels were lower in Sarayköy station in the first sampling period. Among the measured biomarkers, only several LPO degradation products were significantly correlated with OCPs and PCBs in liver tissue.

The present study was designed to investigate the association between levels of organochlorine pesticides (OCPs) and liver enzyme responses in Cyprinus carpio. Fish were caught at three stations in the Büyük Menderes River (BMR): the origin, the Sarayköy station, and the estuary. Seventeen OCPs were quantified in liver tissue, as well as in river water by gas chromatography (GC)-electron capture detection, and structures were confirmed by negative chemical ionization-GC-mass spectrometry. The activities of CYP1A, GST, Se-GPx, CAT, and SODs were determined by spectrophotometry or fluorimetry. The mRNA levels of CYP1A, GST, and SOD1 were quantified by real-time RT-PCR. CYP1A and antioxidant enzyme activities were dramatically higher at the Sarayköy station, where OCP pollution is higher than the other two stations. Mn-SOD is responsible for the increase in total SOD activity in the Sarayköy samples. However, gene expression levels of certain enzymes were heavily suppressed. Our findings show that the transcriptional and functional responses of CYP1A and antioxidant enzymes are inversely correlated., (Copyright © 2014. Published by Elsevier Ireland Ltd.)