Microstructure and Texture Evolution of Mg-Gd-Y-Zr Alloy during Reciprocating Upsetting-Extrusion.

Reciprocating Upsetting-Extrusion (RUE) deformation process can significantly refine the grains size and weaken the basal plane texture by applying a large cumulative strain to the alloy, which is of great significance to weaken the anisotropy of magnesium (Mg) alloys and increase the application range. In this paper, the Mg-8.27Gd-3.18Y-0.43Zr (wt %) alloy was subjected to isothermal multi-passes RUE. The microstructure and texture evolution, crystal orientation-dependent deformation mechanism of the alloy after deformation were investigated. The results clearly show that with the increase of RUE process, the grains are significantly refined through continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) mechanisms, the uniformity of the microstructure is improved, and the texture intensity is reduced. At the same time, a large number of particle phases are dynamically precipitated during the deformation process, promoting grain refinement by the particle-stimulated nucleation (PSN) mechanism. The typical [10-10] fiber texture is produced after one pass due to the basal plane of the deformed grains with a relatively high proportion is gradually parallel to the ED during extrusion process. However, the texture concentration is reduced compared with the traditional extrusion deformation, indicating that the upsetting deformation has a certain delay effect on the subsequent extrusion texture generation. After three or four passes deformation, the grain orientation is randomized due to the continuous progress of the dynamic recrystallization process.

The Role of Long Period Stacking Ordered Phase in Dynamic Recrystallization of a Mg-Gd-Y-Zn-Zr Alloy during Multi-Directional Forging Process.

The Mg-Gd-Y-Zn-Zr alloy containing a long period stacking ordered (LPSO) phase was subjected to multi-pass deformation by means of a multi-directional forging process, and the microstructure evolution and the influence of the LPSO phase on its dynamic recrystallization (DRX) were studied. The results showed that multi-directional forging can effectively refine the grain with the DRX fraction increased, and DRXed grains lead to the decrease of the texture intensity, which can significantly improve the mechanical properties of the alloy. The different morphologies of the LPSO phase have different degrees of promotion relative to DRX behavior. The lamellar LPSO phase with kinks promoted dislocation plugging, where there could be a potential nucleation site for DRX grains. The fragmented lamellar LPSO phase promoted the DRX process through the particle-stimulated nucleation mechanism, and the block-shaped phase was more prone to stress concentration, which promoted DRX. These effects resulted in continuous grain refinement and a more uniform microstructure.

Dietary methionine restriction improves the impairment of cardiac function in middle-aged obese mice.

Dietary methionine restriction (MR) has been reported to extend lifespan, reduce obesity and decrease oxidative damage to mtDNA in the heart of rats, and increase endogenous hydrogen sulfide (H2S) production in the liver and blood. H2S has many potential benefits in the pathophysiology of the cardiovascular system. MR also increases the level of homocysteine (Hcy) in the liver and plasma, but elevated plasma Hcy is a risk factor for cardiovascular disease. Therefore, this study aimed to determine the effect of MR on cardiac function and metabolic status in obese middle-aged mice and its possible mechanisms. C57BL/6J mice (aged approximately 28 weeks) were divided into six dietary groups: CON (0.86% methionine + 4% fat), CMR40 (0.52% methionine + 4% fat), CMR80 (0.17% methionine + 4% fat), HFD (0.86% methionine + 24% fat), HMR40 (0.52% methionine + 24% fat) and HMR80 (0.17% methionine + 24% fat) for 15 consecutive weeks. Our results showed that 80% MR improves systolic dysfunction in middle-aged obese mice and enhances myocardial energy metabolism. 80% MR also reduces myocardial oxidative stress and improves inflammatory response. In addition, 80% MR increased mice Hcy levels and activated remethylation and transsulfur pathways of Hcy and promoted endogenous H2S production in the heart. 40% MR has the same trend, but is not significant. Moreover 40% MR at variance with 80% MR, did not decrease the body weight in both control and high-fat diet mice. These findings suggest that MR can improve myocardial energy metabolism, reduce heart inflammation and oxidative stress by increasing cardiac H2S production, and improve cardiac dysfunction in middle-aged obese mice.

Factors Associated with Interstitial Lung Disease in Patients with Polymyositis and Dermatomyositis: A Systematic Review and Meta-Analysis.

OBJECTIVES: Interstitial lung disease (ILD) is an extramuscular manifestation that results in increased morbidity and mortality from polymyositis (PM) and dermatomyositis (DM). The aim of this study was to systematically evaluate risk factors associated with the development of ILD in PM/DM. METHODS: Observational studies were identified from searching PubMed, Medline, Embase, and the Cochrane Library. Pooled odds ratios (ORs) or standardized mean differences (SMDs) and corresponding 95% confidence intervals (CIs) were obtained for the relationships between risk factors and ILD in PM/DM using either fixed- or random-effects models, whichever were appropriate. Heterogeneity tests, sensitivity analyses, and publication bias assessments were also performed. RESULTS: Twenty-three studies were selected for a meta-analysis that included 834 patients and 1245 control subjects. Risk factors that may have increased the risk of developing ILD in PM/DM patients included older age at diagnosis (SMD, 0.35; 95% CI, 0.18-0.52; P < 0.0001), arthritis/arthralgia (OR, 3.17; 95% CI, 1.99-5.04; P < 0.00001), fever (OR, 2.31; 95% CI, 1.42-3.76; P = 0.0007), presence of anti-Jo-1 antibodies (OR, 3.34; 95% CI, 2.16-5.16; P < 0.00001), elevated erythrocyte sedimentation rate (ESR; SMD, 0.48; 95% CI, 0.32-0.64; P < 0.00001), presence of anti-MDA5 antibodies (OR, 18.26; 95% CI, 9.66-34.51; P < 0.00001), and elevated C-reactive protein level (CRP; OR, 3.50; 95% CI, 1.48-8.28; P = 0.004). Meanwhile, malignancy (OR, 0.36; 95% CI, 0.18-0.72; P = 0.004) reduced the risk of developing ILD in PM/DM patients. CONCLUSION: Our meta-analysis results suggest that the association between PM/DM and ILD may be due to such risk factors as older age at diagnosis, arthritis/arthralgia, fever, presence of anti-Jo-1 antibodies, elevated ESR, presence of anti-MDA5 antibodies, and elevated CRP level, while malignancy was associated with a reduced risk of developing ILD. Thus, these variables may be used to guide screening processes for ILD in patients with PM/DM.