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In this paper, (0.2–1 wt%) Yb was added to improve the tensile properties and high-cycle fatigue behavior of the as-cast and as-extruded Mg-10Li-5Zn-0.5Er alloys. It is found that Yb mainly affects the mechanical properties of the alloy by changing the grain size, type and morphology of the second phases. Yb mainly exists in the formation of Mg2Yb and Mg-Zn-Yb phases in the metallographic structure. With the addition of Yb, the grains are refined and these Yb-containing phases replace the large-sized MgLiZn phase to be enriched at the grain boundaries. While the addition of excess Yb reduces the number of small-sized MgLiZn phases in the grain, thus reducing the alloys’ mechanical performance. After extrusion, the small-sized MgLiZn phase is refined and the number increases, which effectively improves the tensile and fatigue strength of the alloy. The fatigue strength is mainly affected by the number and morphology of the second phase, positively correlated with the strength. Balanced in grain size and number and size of second phases, the extruded alloy with 0.2Yb added exhibits excellent mechanical properties with the yield strength, ultimate tensile strength and elongation of 292 MPa, 303 MPa and 11.7%, and an fatigue strength of 130 MPa.

Abstract Background Post-radiation nasopharyngeal necrosis (PRNN) is a severe adverse event following re-radiotherapy for patients with locally recurrent nasopharyngeal carcinoma (LRNPC) and associated with decreased survival. Biological heterogeneity in recurrent tumors contributes to the different risks of PRNN. Radiomics can be used to mine high-throughput non-invasive image features to predict clinical outcomes and capture underlying biological functions. We aimed to develop a radiogenomic signature for the pre-treatment prediction of PRNN to guide re-radiotherapy in patients with LRNPC. Methods This multicenter study included 761 re-irradiated patients with LRNPC at four centers in NPC endemic area and divided them into training, internal validation, and external validation cohorts. We built a machine learning (random forest) radiomic signature based on the pre-treatment multiparametric magnetic resonance images for predicting PRNN following re-radiotherapy. We comprehensively assessed the performance of the radiomic signature. Transcriptomic sequencing and gene set enrichment analyses were conducted to identify the associated biological processes. Results The radiomic signature showed discrimination of 1-year PRNN in the training, internal validation, and external validation cohorts (area under the curve (AUC) 0.713–0.756). Stratified by a cutoff score of 0.735, patients with high-risk signature had higher incidences of PRNN than patients with low-risk signature (1-year PRNN rates 42.2–62.5% vs. 16.3–18.8%, P

The present work reports the creep behavior and microstructural evolution of the sand-cast Mg–14Gd–0.4Zr alloy (wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 °C were performed under various applied stresses (i.e., 60, 80 and 100 MPa). Among them, the sand-cast Mg–14Gd–0.4Zr samples examined under 250 °C/80 MPa for 39 and 95 h, respectively, were chosen to systemically analyze their creep mechanisms using high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM). The obtained results showed that the enhancement of creep resistance can be mainly attributed to the coherent β' and β'F phases with an alternate distribution, effectively impeding the basal dislocations movement. However, with the creep time increasing, the fine β'+β'F precipitate chains coarsened and transformed to semi-coherent β1 phase and even to large incoherent β phase (surrounded by precipitate-free areas) in grain interiors. The precipitate-free zones (PFZs) at grain boundaries (GBs) were formed, and they could expand during creep deformation. Apart from the main cross-slip of basal and prismatic dislocations, type dislocations were activated and tended to distribute near the GBs. The aforementioned phenomena induced the stress concentrations, consequently leading to the increment of the creep strain.

In order to improve the ductility of commercial WE43 alloy and reduce its cost, a Mg-3Y-2Gd-1Nd-0.4Zr alloy with a low amount of rare earths was developed and prepared by sand casting with a differential pressure casting system. Its microstructure, mechanical properties and fracture behaviors in the as-cast, solution-treated and as-aged states were evaluated. It is found that the aged alloy exhibited excellent comprehensive mechanical properties owing to the fine dense plate-shaped β' precipitates formed on prismatic habits during aging at 200 °C for 192 hrs after solution-treated at 500 °C for 24 hrs. Its ultimate tensile strength, yield strength, and elongation at ambient temperature reach to 319 ± 10 MPa, 202 ± 2 MPa and 8.7 ± 0.3% as well as 230 ± 4 MPa, 155 ± 1 MPa and 16.0 ± 0.5% at 250 °C. The fracture mode of as-aged alloy was transferred from cleavage at room temperature to quasi-cleavage and ductile fracture at the test temperature 300 °C. The properties of large-scale components fabricated using the developed Mg-3Y-2Gd-1Nd-0.4Zr alloy are better than those of commercial WE43 alloy, suggesting that the new developed alloy is a good candidate to fabricate the large complex thin-walled components.

[Objective] The purpose of this study was to carry out a quantitative evaluation of black soil protection policies to provide a scientific basis for the sustainable and efficient operation of black soil protection policy in the future. [Methods] Based on the policy modeling consistency (PMC) index model, a quantitative evaluation of China’s black soil protection policy text was conducted from three aspects: policy path, policy tools, and policy evaluation. [Results] (1) The number of policies related to the protection of black soil has shown a trend of phased growth, with the characteristics of strong effectiveness of the command type documents temporally, and neighborhood effect, ripple effect, and imitation learning spatially. Among them, Inner Mongolia is at the perfect level (7.91), Hei Longjiang (7.33) and Liao ning (7.07) are at the excellent level and Central (6.33) and Ji lin are at the good level (6.00). (2) China’s black soil protection policy tools have been constantly improving. Any use of policy tools for black soil protection has played an important role in a certain period of time. Specifically, the use of black land protection policy tools presents a situation of “performance evaluation > technologicalinnovation>farmland quality management > agricultural support and protection subsidies > farmland quantity protect ion”. (3) The design of the five selected black soil protection sample policies is generally reasonable, but there is still much room for improvement. Inner Mongolia scored the highest, Heilongjiang and Liaoning Provinces showed excellent performance, and the central level and Jilin Province showed reasonable performance. [Conclusion] We recommend that each region should consider its own characteristics and the current status of black soil protection, formulate strong and operational policy plans tailored to local conditions, and actively create a good environment for innovative development of black soil protection.