Crystal Plasticity Finite Element Modeling of the Influences of Ultrafine-Grained Austenite on the Mechanical Response of a Medium-Mn Steel

Medium manganese (medium-Mn) steel, one of the third-generation advanced high-strength steels (AHSS), delivers impressive mechanical properties such as high yield strength, ultimate tensile strength, and uniform elongation. One notable feature of medium-Mn steels is the presence of ultrafine-grained (UFG) austenite, achieved through phase transformation from the parent martensite phase during intercritical annealing. While, in general, UFG is considered a strengthening mechanism, the impact of UFG austenites in medium-Mn steel has not been fully studied. In this manuscript, we advance our previous work on crystal plasticity simulation based on the Taylor model to consider fully resolved high-fidelity microstructures and systematically study the influence of the UFG austenites. The original microstructure with UFG is reconstructed from a set of serial electron backscatter diffraction (EBSD) scans, where the exact grain morphology, orientation, and phase composition are preserved. This microstructure was further analyzed to identify the UFG austenites and recover them to their parent martensite before the intercritical annealing. These two high-fidelity microstructures are used for a comparative study using dislocation density-based crystal plasticity finite modeling to understand the impact of UFG austenites on both the local and overall mechanical responses.</p

Gene amplification of the menkes (MNK; ATP7A) P-type ATPase gene of CHO cells is associated with copper resistance and enhanced copper efflux

Three copper-resistant variants of cultured Chinese hamster ovary (CHO) cells were isolated and each was shown to accumulate less intracellular copper than the parental cells when grown in copper-supplemented media. The reduced copper accumulation was related to enhanced copper efflux. As cultured cells from patients with Menkes disease (mutations in MNK; ATP7A gene) accumulate copper, probably due to defective copper efflux, we investigated the possible role of the MNK gene in the molecular basis of copper resistance. We found increased MNK mRNA and MNK protein in all three resistant variants. The MNK protein, which has not been previously demonstrated experimentally in mammalian cells, was observed to have an apparent molecular weight of 178 kDa on SDS gels. The degree of increase in MNK mRNA and protein correlated well with the level of copper resistance and extent of copper efflux. By Southern blot and FISH analysis we determined that the molecular basis for overexpression of MNK was genomic amplification of the MNK gene. These data, combined with the clinical and cellular phenotype in Menkes disease, provide strong evidence that the MNK protein is involved in transmembrane copper efflux, and demonstrate a new system of gene amplification in mammalian cells. © 1995 Oxford University Press

Nanoscale niobium oxides anode for electrochemical lithium and sodium storage: a review of recent improvements

Abstract: In recent years, Nb-based oxides, especially Nb2O5, due to their unique structural advantages, have stimulated scholars’ extensive research enthusiasm in the field of energy storage systems including lithium ion batteries (LIBs) and sodium ion batteries (SIBs), excellent chemical stability and outstanding rate capability dominated by pseudocapacitive nature. In addition, Nb-based oxides usually have a higher operating voltage (> 1.0 V vs Li+/Li), which can effectively prevent the decomposition of organic electrolytes and the formation of solid electrolyte interface films in batteries. This review systematically summarizes the different crystal structures of Nb2O5 and the lithium storage mechanism based on theoretical calculations, as well as the comparison of various synthesis strategies. In addition, the advanced research progress of niobium-based oxides as anode materials in LIBs and SIBs is summarized from the perspective of nanostructure control engineering that affects electrochemical performance. It also puts forward reasonable cognition and challenges for future research, which is conducive to the design of energy storage equipment that meets the needs of sustainable development. Graphic abstract: The design and optimization of various synthesis methods facilitate the formation of a variety of heterogeneous nanostructures, leading to reversible storage of Li and Na ions. [Figure not available: see fulltext.