RESUMEN
Al-Zn-Mg-Si alloy coatings have been developed to inhibit the corrosion of cold-rolled steel sheets by offering galvanic and barrier protection to the substrate steel. It is known that Fe deposited from the steel strip modifies the microstructure of the alloy. We cast samples of Al-Zn-Mg-Si coating alloys containing 0.4 wt% Fe and directionally solidified them using a Bridgman furnace to quantify the effect of this Fe addition between 600 °C and 240 °C. By applying a temperature gradient, growth is encouraged, and by then quenching the sample in coolant, the microstructure may be frozen. These samples were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to determine the morphological effects of the Fe distribution across the experimental temperature range. However, due to the sub 1 wt% concentration of Fe, synchrotron X-ray fluorescence microscopy (XFM) was applied to quantitatively confirm the Fe distribution. Directionally solidified samples were scanned at 7.05 keV and 18.5 keV using X-ray fluorescence at the Australian Synchrotron using the Maia array detector. It was found that a mass nucleation event of the Fe-based τ6 phase occurred at 495 °C following the nucleation of the primary α-Al phase as a result of a peritectic reaction with remaining liquid.
RESUMEN
Dross in a Zn-55wt%Al-1.6wt%Si metal coating bath is a mixture of bath metal and the quaternary intermetallic phase τ5c-Al20Fe5Si2(+Zn). Understanding the properties and formation of dross in a hot-dip Al-Zn galvanizing bath at the processing temperature (~600 °C) is critical for improving the production quality of steel sheet coating. However, dross analysis is usually conducted at room temperature with dross samples taken from the hot-dip bath and it is not known how representative these samples are of the phase(s) existing at high temperature. Using in-situ synchrotron X-ray diffraction (XRD), the crystal lattice and the coefficient of thermal expansion (CTE) of the intermetallic phase have been determined in the temperature range of 30 °C to 660 °C. Phase formation and phase stability of the intermetallic phase in the dross powder have been determined, providing fundamental knowledge for optimizing the production and quality of steel sheet coating.
RESUMEN
3D printing (or more formally called additive manufacturing) has the potential to revolutionize the way objects are manufactured, ranging from critical applications such as aerospace components to medical devices, making the materials stronger, lighter and more durable than those manufactured via conventional methods. While the mechanical properties of Ti-6Al-4V parts manufactured with two major 3D printing techniques: selective laser melting (SLM) and electron beam melting (EBM), have been reported, it is unknown if the corrosion resistance of the 3D-printed parts is comparable to that of the alloy made with isothermal forging (ISF). The aim of this study was to identify the corrosion resistance and mechanisms of Ti-6Al-4V alloy manufactured by SLM, EBM and ISF via electrochemical corrosion tests in 3.5% NaCl solution, focusing on the effect of microstructures. It was observed that the equiaxed α + ß microstructure in the ISF-manufactured Ti-6Al-4V alloy had a superior corrosion resistance to the acicular martensitic α' + ß and lamellar α + ß microstructures of the 3D-printed samples via SLM and EBM, respectively. This was mainly due to the fact that (1) a higher amount of ß phase was present in the ISF-manufactured sample, and (2) the fraction of phase interfaces was lower in the equiaxed α + ß microstructure than in the acicular α' + ß and lamellar α + ß microstructures, leading to fewer microgalvanic cells. The lower corrosion resistance of SLM-manufactured sample was also related to the higher strain energy and lower electrochemical potential induced by the presence of martensitic twins, resulting in faster anodic dissolution and higher corrosion rate.
RESUMEN
Metabolic reprogramming refers to the transformation of the whole metabolic network covering glycolysis and mitochondrial metabolism, which is primarily manifested as the Warburg effect and mitochondrial metabolic reprogramming. Propofol (Pro) has been testified to suppress the malignancy of diversified human cancers. Nevertheless, its role in glycolysis is still uncertain. The purpose of this study was to determine whether Pro modulated glycolysis in ovarian cancer (OC) cells. Cell proliferation, apoptosis, migration, and invasion were tested via CCK-8, flow cytometry, and Transwell assays, respectively, and glucose intake, lactic acid, and ATP production were also determined. Pro restrained glycolysis via mediating the circular RNA-zinc finger RNA-binding protein (ZFR)/microRNA (miR)-212-5p/superoxide dismutase 2 (SOD2) axis. Additionally, Pro restrained cancer cell advancement via modulating circ-ZFR/miR-212-5p/SOD2 axis. In short, Pro restrained glycolysis via mediating the circ-ZFR/miR-212-5p/SOD2 axis. These results offered a better theoretical foundation for comprehending the molecular pathology of OC and provided a novel target for OC diagnosis and treatment.
Asunto(s)
MicroARNs , Neoplasias Ováricas , Propofol , Línea Celular Tumoral , Proliferación Celular/genética , Femenino , Glucólisis/genética , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Neoplasias Ováricas/patología , ARN Circular/genética , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Superóxido Dismutasa , Dedos de ZincRESUMEN
Ga and Ga-based alloys have received significant attention for applications in the liquid state and also for their potential as a bonding material in microelectronic assemblies. This study investigates the phase stability of the CuGa2 phase as a product of the interfacial reaction between liquid Ga and Cu-10Ni substrates at room temperature. In the binary Ga-Cu system, CuGa2 is decomposed into liquid Ga and Cu9Ga4 as the temperature increases to around 260 °C, which prevents the widespread application of this alloy. In contrast to CuGa2 grown from a pure Cu substrate, CuGa2 from the Cu-10Ni substrate shows an increase in the decomposition temperature during heating from 25 to 300 °C. According to our first-principle calculations, there is only a minor difference in the total free energy between Ni solute at the Cu sublattice and the Ga sublattice in the tetragonal CuGa2 crystal structure. This result indicates that both of the sublattices can accommodate the dilute Ni solute with comparable probability. Regardless of the sublattice where the Ni impurities are located, the presence of diluted Ni in the matrix stabilizes the CuGa2 system by inducing some localized Ni 3d states at energy levels near the Fermi level. It is also shown that the formation of Cu antisite defects, which also stabilizes CuGa2, is preferable if the CuGa2 matrix is grown on a Ni-containing substrate.
RESUMEN
In this work we review our new methods to computer generate amorphous atomic topologies of several binary alloys: SiH, SiN, CN; binary systems based on group IV elements like SiC; the GeSe2 chalcogenide; aluminum-based systems: AlN and AlSi, and the CuZr amorphous alloy. We use an ab initio approach based on density functionals and computationally thermally-randomized periodically-continued cells with at least 108 atoms. The computational thermal process to generate the amorphous alloys is the undermelt-quench approach, or one of its variants, that consists in linearly heating the samples to just below their melting (or liquidus) temperatures, and then linearly cooling them afterwards. These processes are carried out from initial crystalline conditions using short and long time steps. We find that a step four-times the default time step is adequate for most of the simulations. Radial distribution functions (partial and total) are calculated and compared whenever possible with experimental results, and the agreement is very good. For some materials we report studies of the effect of the topological disorder on their electronic and vibrational densities of states and on their optical properties.