Unusual behavior of the Portevin - Le Chatelier effect in an AlMg alloy containing precipitates

Stress serration patterns and kinematics of deformation bands associated with the Portevin - Le Chatelier effect in an Al-Mg alloy were investigated by analyzing the evolution of the applied stress and axial strain distribution. In contrast to usually observed strain localization behaviors, referring to propagating and static deformation bands at high and low strain rates, respectively, the propagation mode was found to persist in a wide strain-rate rang

Dislocation transport and intermittency in the plasticity of crystalline solids

International audienceWhen envisioned at the relevant length scale, plasticity of crystalline solids consists in the transport of dislocations through the lattice. In this paper, transport of dislocations is evidenced by experimental data gathered from high-resolution extensometry carried out on copper single crystals in tension. Spatiotemporal kinematic fields display spatial correlation through characteristic lines intermittently covered by plastic activity. Intermittency shows temporal correlation and power-law distribution of avalanche size. Interpretation of this phenomenon is proposed within the framework of a field dislocation theory attacking the combined problem of dislocation transport and long-range internal stress field development. Intermittency and transport properties show remarkable independence from sample size, aspect ratio, loading rate, and strain-rate sensitivity of the flow stress

Peculiar spatiotemporal behavior of unstable plastic flow in an AlMgMnScZr alloy with coarse and ultrafine grains

The work addresses the effects of nanosize particles and grain refinement on the patterns of stress serrations and kinematics of deformation bands associated with the Portevin–Le Chatelier instability of plastic flow. The results are discussed from the viewpoint of competition between various dynamical modes of plastic deformation associated with collective dynamics of dislocation

Treatment of atopic dermatitis with upadacitinib: adcare single center experience

IntroductionThe role of upadacitinib in the management of moderate to severe atopic dermatitis seems promising, but more data on its efficacy and safety are needed. This study endeavors to assess the practical impact and safety of upadacitinib in patients with moderate to severe atopic dermatitis. The study aims to evaluate the efficacy and safety of upadacitinib in the treatment of moderate to severe atopic dermatitis, focusing on analyzing patient responses to the treatment.MethodsIn this study, adult patients diagnosed with moderate to severe atopic dermatitis received upadacitinib at daily doses of 15 mg or 30 mg, as prescribed by their attending physicians. The therapeutic efficacy of upadacitinib was meticulously assessed using established clinical metrics. Simultaneously, a comprehensive safety assessment was conducted through monthly monitoring, including the evaluation of potential effects of upadacitinib intake on hepatic function, lipid profile, and hematopoiesis using the pertinent laboratory tests.ResultsSixteen participants were enrolled in the study. At 1month follow-up, there was a significant reduction in the mean Eczema Area and Severity Index (EASI) score to 18.8 points, which further increased to 24 points at the 4-month mark. Additionally, 9 participants (56%) demonstrated an EASI-50 response after 1 month of treatment, with this response increasing to 9 participants (90%) after 4 months. Furthermore, enhanced therapeutic responses were observed at 4 months, with 6 patients (38%) achieving an EASI-75 response at 1month and 8 patients (80%) achieving this milestone at the 4-month follow-up. This study highlights the potential of upadacitinib as an effective treatment option for moderate to severe atopic dermatitis. While it demonstrates improved symptom management, close monitoring for potential adverse events, particularly infections and the known risks of Janus kinase inhibitors, is essential. Further research is essential to determine the long-term safety and efficacy of upadacitinib

Intermittency and Deformation Band Propagation in an Austenitic FeMnC TWIP Steel

Plastic deformation of austenitic FeMnC TWIP steels exhibits complex spatiotemporal patterns associated with the occurrence of deformation bands and the concomitant fluctuations of the deforming stress. Although the plastic instability is a generic property of these steels and is usually attributed to interaction of dislocations with solutes (the Portevin-Le Chatelier effect), both the kinematics of the deformation bands and the characteristic shape of stress serrations observed in the carbon-containing TWIP steel at room temperature manifest unusual features. The nature of these peculiarities and the mechanism of jerky flow in such steels are unclear. In the present work, an attempt is made to get an insight into the jerky flow in the Fe22Mn0.6C steel by studying the time series characterizing the evolution of plastic deformation at various scales: stress-time curves, local strain field, and acoustic emission accompanying the deformation processes. Stress and strain fluctuations related to two distinct scale ranges are detected and characterized

Effect of microstructure on continuous propagation of the Portevin–Le Chatelier deformation bands

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Effect of the surface mechanical attrition treatment on multiscale complexity of the Portevin-Le Chatelier effect in an AlMg alloy

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