| 1. |
- Deirmina, Faraz, et al.
(författare)
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Influence of boron on the stress-rupture behavior of an additively manufactured Hastelloy X
- 2023
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 863
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Tidskriftsartikel (refereegranskat)abstract
- The influence of minor additions of boron and the as-built (AB) microstructure on stress-rupture behavior of a modified crack-free Hastelloy X fabricated by laser powder bed fusion (L-PBF) was investigated. Isothermal stress rupture tests were performed at 816 degrees C under a static tensile load of 103 MPa. Micro-void formation in the vicinity of carbide precipitates and their coalescence was only observed at chevron-like high-angle grain boundaries, characteristic of L-PBF process. These grain boundaries, laying on the planes with maximum resolved shear stress with respect to the loading direction, directly governed the intergranular crack propagation. In view of the fracture mechanism and the time to rupture, increasing boron content significantly improves timeto-rupture through a diffusion-controlled mechanism by hindering the carbon diffusion to the grain boundaries. Adequate additions of boron (>10 ppm) guarantee the stress-rupture properties (strength) of the AB components without the need for additional post-thermal treatments. Further increase in boron content (i.e., 30 ppm), led to about five times increase in time to rupture (500 h vs. 110 h), and significantly improved creep elongation (30% vs. 9%) compared with the low boron alloy.
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| 3. |
- Movérare-Skrtic, Sofia, et al.
(författare)
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Dihydrotestosterone treatment results in obesity and altered lipid metabolism in orchidectomized mice.
- 2006
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Ingår i: Obesity (Silver Spring, Md.). - : Wiley. - 1930-7381 .- 1930-739X. ; 14:4, s. 662-72
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To determine the role of androgen receptor (AR) activation for adipose tissue metabolism. Sex steroids are important regulators of adipose tissue metabolism in men. Androgens may regulate the adipose tissue metabolism in men either directly by stimulation of the AR or indirectly by aromatization of androgens into estrogens and, thereafter, by stimulation of the estrogen receptors. Previous studies have shown that estrogen receptor alpha stimulation results in reduced fat mass in men. RESEARCH METHODS AND PROCEDURES: Orchidectomized mice were treated with the non-aromatizable androgen 5alpha-dihydrotestosterone (DHT), 17beta-estradiol, or vehicle. Vo(2), Vco(2), resting metabolic rate, locomotor activity, and food consumption were measured. Furthermore, changes in hepatic gene expression were analyzed. RESULTS: DHT treatment resulted in obesity, associated with reduced energy expenditure and fat oxidation. In contrast, DHT did not affect food consumption or locomotor activity. Furthermore, DHT treatment resulted in increased high-density lipoprotein-cholesterol and triglyceride levels associated with markedly decreased 7alpha-hydroxylase gene expression, indicating decreased bile acid production. DISCUSSION: We showed that AR activation results in obesity and altered lipid metabolism in orchidectomized mice. One may speculate that AR antagonists might be useful in the treatment of obesity in men.
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