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The recrystallization behavior of cold-rolled Al–Zn–Mg–Cu-based alloy sheets was systematically investigated by varying the Cu and Mg contents. With increasing Cu and Mg contents, the recrystallized grain size was reduced from 54.9 to 23.3 μ m owing to the reduced ratio of the size to volume fraction of microscale particles. Interestingly, the sensitivity of different particles to particle-stimulated nucleation (PSN), which is reflected by the linear experimental coefficient (k), was dependent on their morphologies and relative fractions. The k value was considerably small (0.07) in the Cu-free alloys, implying that the Zn and Mg containing particles have an insignificant effect on the PSN. However, the k value increased significantly to 0.61 with the increase in Cu content to 1.3 wt%, because the rod-shaped Al7Cu2Fe particles formed a large plastic deformation zone around them. The addition of 2.0 wt% Mg led to the increase in the relative fraction of round-shaped Al2CuMg particles, increasing the k value from 0.46 to 0.86. The Al7Cu2Fe particles were a stronger source of PSN than the Al2CuMg particles, forming more recrystallized grains. Although Mg addition could increase the yield strength of the aged sheets, a strength–ductility trade-off arose. However, the addition of Cu simultaneously increased the yield strength and elongation because the uniform distribution of grain boundary precipitates caused by grain refinement could reduce the stress concentration during plastic deformation. [ABSTRACT FROM AUTHOR]

Nuclear fusion is one of the most attractive alternatives to carbon-dependent energy sources1. Harnessing energy from nuclear fusion in a large reactor scale, however, still presents many scientific challenges despite the many years of research and steady advances in magnetic confinement approaches. State-of-the-art magnetic fusion devices cannot yet achieve a sustainable fusion performance, which requires a high temperature above 100 million kelvin and sufficient control of instabilities to ensure steady-state operation on the order of tens of seconds2,3. Here we report experiments at the Korea Superconducting Tokamak Advanced Research4 device producing a plasma fusion regime that satisfies most of the above requirements: thanks to abundant fast ions stabilizing the core plasma turbulence, we generate plasmas at a temperature of 100 million kelvin lasting up to 20 seconds without plasma edge instabilities or impurity accumulation. A low plasma density combined with a moderate input power for operation is key to establishing this regime by preserving a high fraction of fast ions. This regime is rarely subject to disruption and can be sustained reliably even without a sophisticated control, and thus represents a promising path towards commercial fusion reactors.A magnetic confinement regime established at the Korea Superconducting Tokamak Advanced Research device enables the generation of plasmas over 108 kelvin for 20 seconds with the aid of fast ions without plasma edge instabilities or impurity accumulation. [ABSTRACT FROM AUTHOR]

Purpose: To compare helical tomotherapy (HT) and conventional intensity-modulated radiotherapy (IMRT) using a variety of dosimetric and radiobiologic indexes in patients with locally advanced non-small cell lung cancer (LA-NSCLC).Patients and Methods: A total of 20 patients with LA-NSCLC were enrolled. IMRT plans with 4-6 coplanar beams and HT plans were generated for each patient. Dose distributions and dosimetric indexes for the tumors and critical structures were computed for both plans and compared.Results: Both modalities created highly conformal plans. They did not differ in the volumes of lung exposed to > 20 Gy of radiation. The average mean lung dose, volume receiving ≥ 30 Gy, and volume receiving ≥ 10 Gy in HT planning were 18.3 Gy, 18.5%, and 57.1%, respectively, compared to 19.4 Gy, 25.4%, and 48.9%, respectively, with IMRT (p = 0.004, p < 0.001, and p < 0.001). The differences between HT and IMRT in lung volume receiving ≥ 10-20 Gy increased significantly as the planning target volume (PTV) increased. For 6 patients who had PTV greater than 700 cm(3), IMRT was superior to HT for 5 patients in terms of lung volume receiving ≥ 5-20 Gy. The integral dose to the entire thorax in HT plans was significantly higher than in IMRT plans.Conclusion: HT gave significantly better control of mean lung dose and volume receiving ≥ 30-40 Gy, whereas IMRT provided better control of the lung volume receiving ≥ 5-15 Gy and the integral dose to entire thorax. In most patients with PTV greater than 700 cm(3), IMRT was superior to HT in terms of lung volume receiving ≥ 5-20 Gy. It is therefore advised that caution should be exercised when planning LA-NSCLC using HT. [ABSTRACT FROM AUTHOR]