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Residual stress exists extensively in biological and engineering structures. Here we report that residual stress can be engineered to significantly enhance the strength and ductility of gradient materials. In-situ synchrotron experiments revealed that the strongest strain hardening occurred in the layer with the highest compressive residual stress in a gradient structure. This layer remained elastic longer than adjacent layers during tension, producing high hetero-deformation induced stress to increase strength and enhancing work hardening even after the disappearance of the compressive stress to increase ductility. This finding provides a new paradigm for designing gradient structures for superior mechanical properties.

Abstract High-carbon martensite steels (with C > 0.5 wt.%) are very hard but at the same time as brittle as glass in as-quenched or low-temperature-tempered state. Such extreme brittleness, originating from a twin microstructure, has rendered these steels almost useless in martensite state. Therefore, for more than a century it has been a common knowledge that high-carbon martensitic steels are intrinsically brittle and thus are not expected to find any application in harsh loading conditions. Here we report that these brittle steels can be transformed into super-strong ones exhibiting a combination of ultrahigh strength and significant toughness, through a simple grain-refinement treatment, which refines the grain size to ~4 μm. As a result, an ultra-high tensile strength of 2.4~2.6 GPa, a significant elongation of 4~10% and a good fracture toughness (K1C) of 23.5~29.6 MPa m1/2 were obtained in high-carbon martensitic steels with 0.61–0.65 wt.% C. These properties are comparable with those of “the king of super-high-strength steels”—maraging steels, but achieved at merely 1/30~1/50 of the price. The drastic enhancement in mechanical properties is found to arise from a transition from the conventional twin microstructure to a dislocation one by grain refinement. Our finding may provide a new route to manufacturing super-strong steels in a simple and economic way.

Catechins are polyphenolic phytochemicals with many important physiological activities that play a multifaceted health care function in the human body, especially in the prevention of cardiovascular disease. In this paper, various experimental and clinical studies have revealed the role of catechins in the prevention and treatment of cardiovascular disorders, and we review the preventive effects of catechins on cardiovascular disease from the following aspects: Regulating lipid metabolism, regulating blood lipid metabolism, vascular endothelial protection, and reducing blood pressure.

To establish the quantitative analysis multi-components with a single-marker(QAMS) method for six components and fingerprint of standard decoction of Gastrodiae Rhizoma, verify the accuracy and feasibility of the method, and evaluate the quality of standard decoction. Based on UPLC with gastrodin as the internal standard, relative correction factors of p-hydroxybenzyl alcohol, parishin E, parishin B, parishin C, parishin A and gastrodin were determined by investigating the column temperature, flow rate, chromatographic columns and multi-point concentration correction. The total contents in 18 batches of standard decoction of Gastrodiae Rhizoma and the similarity were determined to calculate the similarity. The results of standard curve method, external standard one-point method and quantitative analysis multi-components with a single-marker(QAMS) were compared, and the results showed that there was no significant difference among these three methods. By analyzing the results of standard decoctions from different origins, it can be seen that the quality of Gastrodia standard decoctions derived from Anhui and Yunnan was better, followed by Shaanxi and Hubei, and relatively poor in Gansu, with similarities all above 0.90 in the fingerprints. Therefore, the QAMS method that can measure the contents of gastrodin, p-hydroxybenzyl alcohol, parishin E, parishin B, parishin C and parishin A in standard decoction of Gastrodiae Rhizoma combined with fingerprint is accurate, feasible and fast, which can be used to evaluate the quality of standard decoction of Gastrodiae Rhizoma, and also provide a reference for the research on the quality standards of raw materials for Gastrodiae Rhizoma prepared slices and alike.