Multiscale Simulation of Yield Strength in Reduced-Activation Ferritic/Martensitic Steel

AbstractOne of the important requirements for the application of reduced-activation ferritic/martensitic (RAFM) steel is to retain proper mechanical properties under irradiation and high-temperature conditions. To simulate the yield strength and stress-strain curve of steels during high-temperature and irradiation conditions, a multiscale simulation method consisting of both microstructure and strengthening simulations was established. The simulation results of microstructure parameters were added to a superposition strengthening model, which consisted of constitutive models of different strengthening methods. Based on the simulation results, the strength contribution for different strengthening methods at both room temperature and high-temperature conditions was analyzed. The simulation results of the yield strength in irradiation and high-temperature conditions were mainly consistent with the experimental results. The optimal application field of this multiscale model was 9Cr series (7–9 wt.%Cr) RAFM steels in a condition characterized by 0.1–5 dpa (or 0 dpa) and a temperature range of 25–500°C

Can regional integration narrow city-level energy efficiency gap in China?

Improving energy efficiency is essential for energy conservation, emissions reduction, and sustainable development. Prevalent huge efficiency gaps are not advantageous for the improvement of the region's overall energy efficiency. Although studies have analyzed the influencing factors of the regional energy efficiency gap, the impact of regional integration on the regional energy efficiency gap remains untested. This paper applies the extended stochastic frontier analysis (SFA) method that incorporates time-varying, time-invariant and city heterogeneous characteristics to estimate the city-level energy efficiency in China from 2005 to 2017. Building on the “center-periphery” framework, we further calculate the regional energy efficiency gap and investigate the impact of regional integration on the regional energy efficiency gap through the generalized moment method (GMM). The results show that 1) average city-level energy efficiency is 44.2%, ranging from 2.9% to 75.5%, indicating that China has a huge regional energy efficiency gap; 2) there is a U-shaped relationship between regional integration and the regional energy efficiency gap within city agglomeration. Improvement in regional integration can narrow the regional energy efficiency gap when the degree of regional integration is low, and expand the efficiency gap when regional integration level is high; 3) government intervention will smooth the impact of regional integration on the regional energy efficiency gap within city agglomeration. Practicable policies to mitigate the regional energy efficiency gap in China are suggested and applicable to other emerging economies, especially for those with a huge imbalance in regional energy efficiency

Tectorigenin ameliorates myocardial cell injury caused by hypoxia/reoxygenation by inhibiting autophagy via activation of PI3K/AKT/mTOR pathway

Purpose: To investigate the protective role of tectorigenin in myocardial ischaemia/reperfusion. Methods: Myocardial cells (H9c2) were treated with different concentrations of tectorigenin and exposed to hypoxia/reoxygenation. Cell viability and apoptosis were determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) staining, respectively. Oxidative stress and inflammation were evaluated using enzyme-linked immunosorbent assay (ELISA), while autophagy and the underlying mechanisms of action were evaluated by Western blot. Results: Tectorigenin enhanced the proliferative activity of H9c2 under hypoxia/reoxygenation conditions, and significantly reduced the apoptotic activity (p < 0.001) through decrease in Bax and increase in Bcl-2. Tectorigenin also significantly up-regulated SOD (superoxide dismutase) and GSH (glutathione) levels (p < 0.01), and down-regulated MDA (malondialdehyde) and MPO (myeloperoxidase) in hypoxia/reoxygenation-induced H9c2. TNF-α (tumor necrosis factor-α), IL(interleukin)-1β, and IL-6 levels were also inhibited by tectorigenin by down-regulating p-p65. Hypoxia/reoxygenation-induced increase in p62 and decrease in Beclin-1 and LC3-II/LC3-I were reversed by tectorigenin. Protein expressions of p-mTOR, p-AKT, and p-PI3K in hypoxia/reoxygenation-induced H9c2 were elevated by tectorigenin. Conclusion: Tectorigenin exerts anti-oxidant, anti-inflammatory, and anti-autophagic effects on hypoxia/reoxygenation-induced H9c2 through the activation of PI3K/AKT/mTOR pathway, thus suggesting that it is a potential agent for the management of myocardial ischaemia/reperfusion