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In situ CeB 6 /Al composite has been proven to be an effective refiner for commercial pure aluminum, however, it remains unclear as to the mechanisms of synthesis and grain refinement. We use low-temperature alloying and high-speed melt spinning to optimize the microstructure of CeB 6 . It is found that in situ CeB 6 /Al composite shows controllable microstructure and its refining effect is obviously dependent on the size of CeB 6 particle/cluster. As nano-CeB 6 particles self-assemble into submicron clusters, the inoculant shows significantly enhanced refining effect, reducing the grain size of pure aluminum to ∼110 μm. The refining mechanism is attributed to the combining effect of the cluster structure in submicron scale and the excellent crystallography matching relationship of CeB 6 and Al. Mechanical properties of pure aluminum are also improved by addition of in situ CeB 6 /Al composite inoculant due to collaboration effect of dispersion strengthening and grain refining strengthening. [ABSTRACT FROM AUTHOR]

The CeB 6 /Al inoculant with variable sizes of CeB 6 particles were prepared by arc-melting and controlled by melt-spinning and then verified the refining efficacy in pure aluminum. It was found that the grain refining efficacy can be significantly improved by controlling the CeB 6 particle size. The pure aluminum can be refined from a grain size grade of 870 ± 25 μm to 150 ± 35 μm by addition of CeB 6 /Al ribbon with a very small ratio of 0.4% in weight. Thereafter, the mechanical properties of the pure aluminum, including the tensile strength, yield strength and microhardness, were obviously improved by the addition of the CeB 6 /Al ribbon. The excellent grain refining can be attributed to the nano-sized refiner particles and the well-banded particle/matrix interface which are benefit for the nucleation of aluminum during solidification. It is suggested that the CeB 6 /Al inoculant ribbon is a promising inoculants for aluminum alloy. [ABSTRACT FROM AUTHOR]

Drosha-dependent canonical microRNAs (miRNAs) play a crucial role in the biological functions and development of cancer. However, the effects of Drosha-independent non-canonical miRNAs remain poorly understood. In our previous work, we found a set of aberrant miRNAs, including some upregulated miRNAs, called Drosha-independent noncanonical miRNAs, in Drosha-knockdown gastric cancer (GC) cells. Surprisingly, Drosha-silenced GC cells still retained strong malignant properties (e.g., proliferation ability and cancer stem cell (CSC) characteristics), indicating that aberrantly upregulated non-canonical miRNAs may play an important role in the maintenance of the malignant properties in GC cells that express low Drosha levels. Here, we report that miR-6778-5p, a noncanonical miRNA, acts as a crucial regulator for maintenance of CSC stemness in Drosha-silenced GC cells. MiR-6778-5p belongs to the 5'-tail mirtron type of non-canonical miRNAs and is transcript splice-derived from intron 5 of SHMT1 (coding cytoplasmic serine hydroxymethyltransferase). It positively regulates expression of its host gene, SHMT1, via targeting YWHAE in Drosha-knockdown GC cells. Similar to its family member SHMT2, SHMT1 plays a crucial role in folate-dependent serine/glycine inter-conversion in one-carbon metabolism. In Drosha wild type GC cells, SHMT2 mediates a mitochondrial-carbon metabolic pathway, which is a major pathway of one-carbon metabolism in normal cells and most cancer cells. However, in Drosha-silenced or Drosha low-expressing GC cells, miR-6778-5p positively regulates SHMT1, instead of SHMT2, thus mediating a compensatory activation of cytoplasmic carbon metabolism that plays an essential role in the maintenance of CSCs in gastric cancer (GCSCs). Drosha wild type GCSCs with SHMT2 are sensitive to 5-fluorouracil; however, Drosha low-expressing GCSCs with SHMT1 are 5-FU-resistant. The loss of miR-6778-5p or SHMT1 notably mitigates GCSC sphere formation and increases sensitivity to 5-fluorouracil in Drosha-knockdown gastric cancer cells. Thus, our study reveals a novel function of Drosha-independent noncanonical miRNAs in maintaining the stemness of GCSCs. [ABSTRACT FROM AUTHOR]

In this paper, an efficient route that combined addition of excessive Mg (3.6 wt.%) and a trace of La (0.5 wt.%) as well as subsequent T6 heat treatment has been first proposed to modify the detrimental platelet-like β-Al 5 FeSi Fe-rich intermetallic to valuable granular-like π-Al 8 Mg 3 FeSi 6 phase in eutectic Al–Si die alloys. The results of the DSC analysis revealed that majority of Mg play the leading role for precipitation of large script-like π-phase while rare earth La has the significant effect on modifying the eutectic Si phase simultaneously. A new phenomenon has been found that the morphology of the π-phase transformed from the script-like to fine granular-like by two main stages, including fragmentation and growth during solution treatment. By calculation, the coarsening rate coefficient of the segmented π-phase was about 2.9 × 10 − 19 m 3 /h during growth stage. The tensile testing measurements showed that the ultimate tensile strength (UTS), yield strength (YS), elongation to fracture (EI) and the quality index (Q) of T6 treated eutectic Al–Si die alloys alloying with 3.6 wt.% Mg and 0.5 wt.% La can reach 312 MPa, 270 MPa, 4.28% and 406 MPa respectively, and the enhanced mechanical properties corresponding to the evolution of the microstructure. [ABSTRACT FROM AUTHOR]

• The SARAX code system was extended for full-range spectrum adaptability. • The assembly calculation is based on the improved Tone's method with MOC solver. • The high-efficient 2-D hyperfine group method was developed. For better self-shielded cross-section generation in advanced reactor analysis with full-range spectrum adaptability, the 2-D subassembly calculation capability has been recently developed with several new methods in the SARAX code system. The improved Tone's method was implemented in the 2-D resonance self-shielding by incorporating the MOC to accurately estimate the heterogeneity effect. The 2-D hyperfine group method with on-the-fly collision probability and the adjacent region flux approximation was developed to perform the 2-D slowing-down spectrum calculation. For better consideration of spectral transition effects due to different mean free path of neutrons, the local super-subassembly model and the whole-core equivalent model can be built with the super-homogenization technique. Verification results showed that for different subassembly calculations, the eigenvalue and self-shielded cross-sections of major actinides agreed with the OpenMC solutions. For core calculations of TRIGA and the reactor with irradiation tunnel, the k-effective and power distribution also agreed well with the OpenMC. [ABSTRACT FROM AUTHOR]