In order to improve the stress corrosion cracking resistance of the weldable Al Zn Mg alloys with medium strength, the near solvus pre precipitation following high temperature solution treatment was performed on LC52 ...In order to improve the stress corrosion cracking resistance of the weldable Al Zn Mg alloys with medium strength, the near solvus pre precipitation following high temperature solution treatment was performed on LC52 and 7039 aluminum alloys. The effect of the pre precipitation on the microstructure, age hardening and stress corrosion cracking of LC52 and 7039 alloy was investigated. The results show that the near solvus pre precipitation can be limited on grain boundary and can enhance the discontinuity of grain boundary precipitates. The stress corrosion cracking resistance of aged Al Zn Mg alloys can be improved with non deteriorated strength and plasticity via pre precipitation.展开更多
The use of Zn as micronutrient in husbandry and agriculture practices and also in baby foods and multivitamin supplements have been increased during the last two decades. However, the effect of long term increasing Zn...The use of Zn as micronutrient in husbandry and agriculture practices and also in baby foods and multivitamin supplements have been increased during the last two decades. However, the effect of long term increasing Zn load on the oxidative stress in the body has not been worked so far. The supplementation of pharmacological dosage of Zn in otherwise Zn adequate diet was investigated with the aim if excess Zn in the diet triggers oxidative stress and its conesquence on enzymes of antioxidant defense system. In this study, three groups of rats were fed on semi-synthetic diet containing 20 mg Zn/kg (control, group-I), 40 mg Zn/kg (group-II) and 80 mg Zn/kg (group-III) diet respectively for a period of 6 months. Blood lipid profile in the serum, lipid peroxidation status and the activities of antioxidant enzymes and trace minerals level were estimated both in the liver and kidney of three groups of rats. The study revealed that the gain in body weight increased in rats in Zn concentration dependent manner. The blood lipid profile displayed a significant rise in serum glucose, total lipids, cholesterol, triglycerides, LDL-cholesterol, VLDL-cholesterol whereas HDL-cholesterol showed a reduction in their levels in group-II and III than their control counter parts. The lipid peroxidation products were higher and the enzyme activities of superoxide dismutase, catalase, glutathione-s-transferase, glutathione reductase, glutathione (reduced) and glucose-6-phosphate dehydrogenase were significantly lowered in liver and kidney of group-II and group-III. Their mineral status revealed a higher Zn concentration and lower Cu, Mg and Mn both in liver and kidney. This data suggest that Zn in excess in diet when fed for longer periods of time induces oxidative stress by altering the status of minerals.展开更多
文摘In order to improve the stress corrosion cracking resistance of the weldable Al Zn Mg alloys with medium strength, the near solvus pre precipitation following high temperature solution treatment was performed on LC52 and 7039 aluminum alloys. The effect of the pre precipitation on the microstructure, age hardening and stress corrosion cracking of LC52 and 7039 alloy was investigated. The results show that the near solvus pre precipitation can be limited on grain boundary and can enhance the discontinuity of grain boundary precipitates. The stress corrosion cracking resistance of aged Al Zn Mg alloys can be improved with non deteriorated strength and plasticity via pre precipitation.
文摘The use of Zn as micronutrient in husbandry and agriculture practices and also in baby foods and multivitamin supplements have been increased during the last two decades. However, the effect of long term increasing Zn load on the oxidative stress in the body has not been worked so far. The supplementation of pharmacological dosage of Zn in otherwise Zn adequate diet was investigated with the aim if excess Zn in the diet triggers oxidative stress and its conesquence on enzymes of antioxidant defense system. In this study, three groups of rats were fed on semi-synthetic diet containing 20 mg Zn/kg (control, group-I), 40 mg Zn/kg (group-II) and 80 mg Zn/kg (group-III) diet respectively for a period of 6 months. Blood lipid profile in the serum, lipid peroxidation status and the activities of antioxidant enzymes and trace minerals level were estimated both in the liver and kidney of three groups of rats. The study revealed that the gain in body weight increased in rats in Zn concentration dependent manner. The blood lipid profile displayed a significant rise in serum glucose, total lipids, cholesterol, triglycerides, LDL-cholesterol, VLDL-cholesterol whereas HDL-cholesterol showed a reduction in their levels in group-II and III than their control counter parts. The lipid peroxidation products were higher and the enzyme activities of superoxide dismutase, catalase, glutathione-s-transferase, glutathione reductase, glutathione (reduced) and glucose-6-phosphate dehydrogenase were significantly lowered in liver and kidney of group-II and group-III. Their mineral status revealed a higher Zn concentration and lower Cu, Mg and Mn both in liver and kidney. This data suggest that Zn in excess in diet when fed for longer periods of time induces oxidative stress by altering the status of minerals.
