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Isothermal hot compression tests were conducted on the 6063 aluminum alloy using a Gleeble-3810 thermal simulator at four different strain rates (0.01, 0.1, 1, and 10 s–1) and five different temperatures (300, 350, 400, 450, and 500°C). Based on the constitutive relationship to process the experimental data, processing maps were produced to evaluate the efficiency of power dissipation (η) and identify regimes with flow instability. Processing maps were produced for two regions with relatively high η at a strain of 0.6, namely (300–320)°C/(0.01–0.02) s–1 and (400–500)°C/(0.01–1) s–1. There were also two unstable regions at (300–325)°C/(0.06–1.5) s–1 and (350–500)°C/(3–10) s–1. The microstructures observed by optical microscopy and electron back-scattered diffraction maps indicated that the deformed samples only underwent dynamic recovery under deformation conditions of (300–320)°C/(0.01–0.02) s–1, while at 500°C/0.01 s–1 the samples showed a high degree of dynamic recrystallization and then produced new equiaxed fine grains. At high strain rates, the precipitates had a pinning effect on dislocations, leading to stress concentration. Local plastic deformation occurred, resulting in thermoplastic instability. Therefore, the optimum processing conditions for the 6063 aluminum alloy determined from true stress-strain curves, processing maps, and microstructural analysis were 500°C/0.01 s–1. [ABSTRACT FROM AUTHOR]

Objective: To analyze the effect of age and gender on sulfhydryl compounds content in saliva and plasma in healthy population and to study the relationship between sulfhydryl compounds content of saliva and plasma to provide a basis for clinical examination of saliva sulfhydryl compounds., Methods: Sulfhydryl compounds content of saliva and plasma were measured in 306 healthy adults from the Department of Clinical Laboratory of Health Management lnstitute of General Hospital of Chinese PLA (151 female and 155 male) who were divided into young group (20-44 years old, n = 106, 48 female and 58 male), middle-aged group (45-59 years old, n = 109, 63 female and 46 male) and elderly group (60-79 years old, n = 91, 40 female and 51 male)., Results: Sulfhydryl compounds content in saliva and plasma in 306 healthy adults were (123±27) and (427±124) µmol/L respectively. Sulfhydryl compounds content in saliva and plasma were significantly decreased as age increased (both P < 0.01). Significant differences of sulfhydryl compounds content of saliva and plasma among the young group, middle-aged group and elderly group were found (P < 0.01). No sex difference was observed in saliva sulfhydryl compounds content (P = 0.451), however the sex difference was significant in plasma sulfhydryl compounds content (P = 0.006). There was a significantly positive correlation between sulfhydryl compounds content in saliva and plasma (r = 0.5050, P < 0.01)., Conclusions: Saliva sulfhydryl compounds content can roughly reflect plasma sulfhydryl compounds content. Saliva sulfhydryl compounds test is a promising biological index of aging which could be an alternative of plasma test.