Inhibiting segregation enabled outstanding combination of mechanical and corrosion properties in precipitation-strengthened aluminum alloys

Segregation of solutes to grain boundary(GB)is the dominant restriction on enhancement of mechanical properties and corrosion resistance during aging in precipitation-strengthened aluminum alloys.Here,we innovatively introduce the cyclic deformation by the vibration during aging to eliminate the GB segre-gation,resulting in the formation of the narrow precipitate-free zone(PFZ)widths near the GB,as well as the fine and discontinuous grain boundary precipitations(GBPs).Compared with the traditional peak-aging,the 2014 aluminum alloy treated by thermal cooperative vibration aging(TCVA)exhibits a superb combination of impact toughness and corrosion resistance,and retains the strength and ductility.In ad-dition,the atomic simulations show that TCVA generates numerous vacancies near the GB,but does not change the dislocation density with the increase of cycle time.These results indicate that the vacancy significantly promotes the nucleation and growth of precipitates in the vicinity of GB,resulting in the narrow PFZs and fine discontinuous GBPs.The present work provides the fundamental knowledge and method to inhibit the equilibrium segregation of solutes to GB during aging,and further realizes the precipitation-strengthened aluminum alloys with excellent mechanical and corrosion properties.

lncRNA AC005224.4/miR-140-3p/SNAI2 regulating axis facilitates the invasion and metastasis of ovarian cancer through epithelial-mesenchymal transition

Background:Ovarian cancer is one of the most widespread malignant diseases of the female reproductive system worldwide.The plurality of ovarian cancer is diagnosed with metastasis in the abdominal cavity.Epithelial-mesenchymal transition(EMT)exerts a vital role in tumor cell metastasis.However,it remains unclear whether long non-coding RNA(lncRNA)are implicated in EMT and influence ovarian cancer cell invasion and metastasis.This study was designed to investigate the impacts of lncRNA AC005224.4 on ovarian cancer.Methods:LncRNA AC005224.4,miR-140-3p,and snail family transcriptional repressor 2(SNAI2)expression levels in ovarian cancer and normal ovarian tissues were determined using real-time quantitative polymerase chain reaction(qRT-PCR).Cell Counting Kit-8(CCK-8)and Transwell(migration and invasion)assays were conducted to measure SKOV3 and CAOV-3 cell proliferation and metastasis.E-cadherin,N-cadherin,Snail,and Vimentin contents were detected using Western blot.Nude mouse xenograft assay was utilized to validate AC005224.4 effects in vivo.Dual-luciferase reporter gene assay confirmed the targeted relationship between miR-140-3p and AC005224.4 or SNAI2.Results:AC005224.4 and SNAI2 upregulation and miR-140-3p downregulation were observed in ovarian cancer tissues and cells.Silencing of AC005224.4 observably moderated SKOV3 and CAOV-3 cell proliferation,migration,invasion,and EMT process in vitro and impaired the tumorigenesis in vivo.miR-140-3p was a target of AC005224.4 and its reduced expression level was mediated by AC005224.4.miR-140-3p mimics decreased the proliferation,migration,and invasion of ovarian cancer cells.SNAI2 was identified as a novel target of miR-140-3p and its expression level was promoted by either AC005224.4 overexpression or miR-140-3p knockdown.Overexpression of SNAI2 also facilitated ovarian cancer cell viability and metastasis.Conclusion:AC005224.4 was confirmed as an oncogene via sponging miR-140-3p and promoted SNAI2 expression,contributing to better understanding of ovarian cancer pathogenesis and shedding light on exploiting the novel lncRNA-directed therapy against ovarian cancer.

Cdk phosphorylation licenses Kif4A chromosome localization required for early mitotic progression

The chromokinesin Kif4A controls proper chromosome condensation, congression/alignment, and cytokinesis to ensure faithful genetic inheritance. Here, we report that Cdk phosphorylation of human Kif4A at T1161 licenses Kif4A chromosomal localization, which, in turn, controls Kif4A early mitotic function. Phosphorylated Kif4A （Kif4A^WT） or Cdk phospho-mimetic Kif4A mutant （Kif4A^TE） associated with chromosomes and condensin I （non-SMC subunit CAP-G and core subunit SMC2） to regulate chromosome condensation, spindle morphology, and chromosome congression/alignment in early mitosis. In contrast, Cdk non-phosphorylatable Kif4A mutant （Kif4A^TA） could neither localize on chromosomes nor associate with CAP-G and SMC2. Furthermore, Kif4A^TA could not rescue defective chromosome condensation, spindle morphology, or chromosome congression/alignment in cells depleted of endogenous Kif4A, which activated a mitotic checkpoint and delayed early mitotic progression. However, targeting Kif4A^TA to chromosomes by fusion of Kif4A^TA with Histone H1 resulted in restoration of chromosome and spindle functions of Kif4A, similar to Kif4A^WT and Kif4A^TE, in cells depleted of endogenous Kif4A. Thus, our results demonstrate that Cdk phosphorylation-licensed chromosomal localization of Kif4A plays a critical role in regulating early mitotic functions of Kif4A that are important for early mitotic progression.

Effect of cerium on microstructure,mechanical properties and corrosion properties of Al-Zn-Mg alloy

The effects of trace Ce on the microstructure,mechanical properties and corrosion resistance of Al-Zn-Mg alloy were studied by means of metallographic analysis,scanning electron microscopy(SEM),mechanical tensile test,slow strain rate tensile test,cyclic polarization curve test,electrochemical impedance spectroscopy test and anodic oxidation test.The results show that the addition of trace Ce has little effect on the strength of Al-Zn-Mg alloy,but can significantly improve the corrosion resistance of the alloy;The mechanical properties and corrosion resistance of the alloys decrease significantly with the addition of excessive Ce;the addition of 0.04 wt%Ce can reduce significantly the self-corrosive current density of AlZn-Mg alloy and increase obviously passivation film resistance of the alloy.The stress corrosion sensitivity index decreases from 0.612 to 0.219,which improves the corrosion resistance properties significantly.