Influence of Zinc Chloride Exposure on Microstructure and Mechanical Behavior of Age-Hardened AZ91 Magnesium Alloy.

The AZ91 magnesium alloy was subjected to a complex treatment involving age hardening (supersaturation and artificial aging) and simultaneous surface layer modification. The specimens were supersaturated in contact with a mixture containing varying concentrations of zinc chloride, followed by cooling either in air or water. After supersaturation, the specimens were subjected to artificial aging and then air-cooled. This process resulted in the formation of a surface layer made of zinc-rich phases. The thickness and microstructure of the surface layer were influenced by the process parameters, namely, the zinc chloride content in the mixture and the cooling rate during supersaturation. The treated specimens exhibited favorable tensile strength and greater elongation compared to the as-cast AZ91 alloy, with values comparable to those of the alloy subjected to standard T6 tempering. No cracking of the layer was observed under moderate deformation, though greater deformation resulted in the formation of cracks, primarily in the areas containing the Mg5Al2Zn2 intermetallic phase. The produced layer demonstrated strong metallurgical bonding to the AZ91 substrate.

Osimertinib vs. afatinib as first-line treatment for patients with metastatic non-small cell lung cancer with an EGFR exon 19 deletion or exon 21 L858R mutation.

Background: The optimal treatment sequencing for patients with metastatic epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) remains a subject of debate. In the United States, osimertinib is the preferred EGFR tyrosine kinase inhibitor (TKI) in the first-line setting. However, small retrospective studies suggest that alternative EGFR TKI sequencing strategies may produce similar outcomes. This study aimed to compare the outcomes of patients with metastatic NSCLC harboring an EGFR exon 19 deletion or exon 21 L858R mutation treated with osimertinib vs. afatinib as first-line therapy. Methods: This retrospective, single-institution study examined 86 patients with metastatic EGFR-mutant NSCLC treated with either afatinib (n=15) or osimertinib (n=71) in the first-line setting. The primary outcome was progression-free survival (PFS), and secondary endpoints included time on EGFR TKI, overall survival (OS), and the incidence of adverse events (AEs). Results: There was no difference in the PFS (median: 27.9 vs. 29.0 months, P=0.75), OS (P=0.18), and the median time on first-line EGFR TKI (23.9 vs. 15.2 months, P=0.10) between the afatinib and osimertinib groups, respectively. The number of AEs was also similar between the two treatment groups (P=0.17). Conclusions: In this real-world retrospective study, there were no differences in PFS or OS between patients treated with afatinib or osimertinib in the first-line setting. These findings should be further investigated in larger prospective studies.

Effect of Double-Step and Strain-Assisted Tempering on Properties of Medium-Carbon Steel.

The present work aimed to study the properties of medium-carbon steel during tempering treatment and to present the strength increase of medium-carbon spring steels by strain-assisted tempering (SAT). The effect of double-step tempering and double-step tempering with rotary swaging, also known as SAT, on the mechanical properties and microstructure was investigated. The main goal was to achieve a further enhancement of the strength of medium-carbon steels using SAT treatment. The microstructure consists of tempered martensite with transition carbides in both cases. The yield strength of the DT sample is 1656 MPa, while that of the SAT sample is about 400 MPa higher. On the contrary, plastic properties such as the elongation and reduction in area have lower values after SAT processing, about 3% and 7%, respectively, compared to the DT treatment. Grain boundary strengthening from low-angle grain boundaries can be attributed to the increase in strength. Based on X-ray diffraction analysis, a lower dislocation strengthening contribution was determined for the SAT sample compared to the double-step tempered sample.

Prediction of Behaviour of Thin-Walled DED-Processed Structure: Experimental-Numerical Approach.

Additive manufacturing (AM) becomes a more and more standard process in different fields of industry. There is still only limited knowledge of the relationship between measured material data and the overall behaviour of directed energy deposition (DED)-processed complex structures. The understanding of the structural performance, including flow curves and local damage properties of additively manufactured parts by DED, becomes increasingly important. DED can be used for creating functional surfaces, component repairing using multiple powder feeders, and creating a heterogeneous structure with defined chemical composition. For thin parts that are used with the as-deposited surface, this evaluation is even highly crucial. The main goal of the study was to predict the behaviour of thin-walled structures manufactured by the DED process under static loading by finite element analysis (FEA). Moreover, in this study, the mechanical performance of partly machined and fully machined miniaturized samples produced from the structure was compared. The structure studied in this research resembles a honeycomb shape made of austenitic stainless steel AISI 316L, which is characterized by high strength and ductility. The uncoupled damage models based on a hybrid experimental-numerical approach were used. The microstructure and hardness were examined to comprehend the structural behaviour.

Design and synthesis of highly active MoVTeNb-oxides for ethane oxidative dehydrogenation.

Ethane oxidative dehydrogenation (ODH) is an alternative route for ethene production. Crystalline M1 phase of Mo-V mixed metal oxide is an excellent catalyst for this reaction. Here we show a hydrothermal synthesis method that generates M1 phases with high surface areas starting from poorly soluble metal oxides. Use of organic additives allows control of the concentration of metals in aqueous suspension. Reactions leading to crystalline M1 take place at 190 °C, i.e., approximately 400 °C lower than under current synthesis conditions. The evolution of solvated polyoxometalate ions and crystalline phases in the solid is monitored by spectroscopies. Catalysts prepared by this route show higher ODH activity compared to conventionally prepared catalysts. The higher activity is due not only to the high specific surface area but also to the corrugated lateral termination of the M1 crystals, as seen by atomic resolution electron microscopy, exposing a high concentration of catalytically active sites.

Formation of Oxygen Radical Sites on MoVNbTeOx by Cooperative Electron Redistribution.

A novel pathway of increasing the surface density of catalytically active oxygen radical sites on a MoVTeNb oxide (M1 phase) catalyst during alkane oxidative dehydrogenation is reported. The novel sites form when a fraction of Te4+ is reduced and emitted from the M1 crystals under catalytic operating conditions, without compromising structural integrity of the catalyst framework. Density functional theory calculations show this Te reduction induces multiple inter-related electron transfers, and the associated cooperative effects lead to the formation of O- radicals. The in situ observations identify complex dynamic changes in the catalyst on an atomistic level, highlighting a new way to tailor structure and dynamics for highly active catalysts.

Atomic-Scale Determination of Active Facets on the MoVTeNb Oxide M1 Phase and Their Intrinsic Catalytic Activity for Ethane Oxidative Dehydrogenation.

Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) has been used to image the basal {001} plane of the catalytically relevant M1 phase in MoVTeNb complex oxides. Facets {010}, {120}, and {210} are identified as the most frequent lateral termination planes of the crystals. Combination of STEM with He ion microscopy (HIM) images, Rietveld analysis, and kinetic tests reveals that the activation of ethane is correlated to the availability of facets {001}, {120}, and {210} at the surface of M1 crystals. The lateral facets {120} and {210} expose crystalline positions related to the typical active centers described for propane oxidation. Conversely, the low activity of the facet {010} is attributed to its configuration, consisting of only stable M6 O21 units connected by a single octahedron. Thus, we quantitatively demonstrated that differences in catalytic activity among M1 samples of equal chemical composition depend primarily on the morphology of the particles, which determines the predominant terminating facets.