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To improve the welding performance of aluminum alloys, a thermal source model of an irregular weld seam was established. COMSOL software was used for numerical simulation of the weld seam geometry effect on the temperature and stress fields in laser welding, which results were experimentally validated. The results show that the ellipsoidal laser welding melted micropool exhibited quasi-steady-state temperature field characteristics. The temperature gradient and thermal stress showed an increase followed by a decline. The temperature fluctuation amplitude of the square-tooth-shaped weld seam exceeded that of the arc-toothshaped one. The temperature evolution of the broken line tooth-shaped weld seam showed a slightly increasing trend, except for the inflection point. The experimental average tensile strength of the weld seam was the highest, reaching about 210 MPa, i.e., roughly 85% of the base material (245 MPa), which coincided with the COMSOL-based temperature field simulation results. With increasing deformation amplitude and transition radius, the maximum tensile force, tensile strength, and elongation at fracture showed an increasing trend. However, the deformation amplitude should be below a certain limit because its increase elongates the welding path and reduces the distance between weld seams, resulting in serious heat accumulation. The tensile fracture morphology of the 6063-T6 base material was curved shear, with shallow toughness pits, small tearing edges at the edges, and small granular objects, indicating small plastic deformation during the fracture process. The tensile fracture of the welded part spanned the weld seam and the base material, and the fracture occurred along the tangent direction of the weld seam. The fracture surface was smooth, the tearing edges at the edge of the toughness pit shifted along the weld seam direction, forming many co-directional slip bands, with highly pronounced plastic deformation. [ABSTRACT FROM AUTHOR]

To achieve directional solidification repair of damaged aviation turbine blades, the directional growth repair layer was prepared using a Nd:YAG laser on the surface of superalloy DZ-22. A scanning electron microscope (SEM) was used to observe the microstructure. The element distribution was analyzed and the microhardness of the sample was measured. The results showed that primary dendrite size was proportional to the current and the pulse-width, and inversely proportional to the scanning speed. No obvious macrosegregation of the repair zone was evident. The zone exhibited a finer microstructure than the substrate and had a smaller columnar crystal size, which was approximately two orders of magnitude smaller than the substrate. The micro-segregation between the centers and the edges of the dendrites and in between adjacent dendrites and a decrease in microhardness from the repair zone (455 HV) to the substrate also were observed. [ABSTRACT FROM AUTHOR]

Several microRNAs (miRNAs) have been identified to play roles in adipocyte differentiation. However, little is known about their involvement in the differentiation of ovine intramuscular adipocytes. Here, the role of one such miRNA, miR-340-5p, in ovine adipocyte differentiation was investigated. Stromal vascular (SV) cells were isolated from skeletal muscle tissues of 1-month-old lambs and induced to differentiate into mature adipocytes. miRNA mimics and inhibitors were used for miR-340-5p overexpression and knockdown assays. For overexpression and knockdown of activating transcription factor 7 (ATF7), lentivirus infection was performed. Luciferase reporter assay was performed to determine the relationship between miR-340-5p and ATF7. The expression of adipogenesis marker genes, PPARγ, C/EBPα, FABP4, ADIPOQ, and ACC, and formation of lipid droplets were detected after the overexpression and inhibition of miR-340-5p, or upon overexpression or knockdown of ATF7. miR-340-5p inhibited the expression of the marker genes and the formation of lipid droplets. ATF7 positively regulated the expression of the marker genes and the formation of lipids. Thus, ATF7 is the target of miR-340-5p in sheep. Overall, these findings indicate that miR-340-5p acts as an inhibitor of the differentiation of intramuscular adipocytes by targeting ATF7. Our study provides a new theoretical basis for improving sheep meat quality. [ABSTRACT FROM AUTHOR]

Silicone-based elastomers (SEs) have been extensively applied in numerous cutting-edge areas, including flexible electronics, biomedicine, 5G smart devices, mechanics, optics, soft robotics, etc. However, traditional strategies for the synthesis of polymer elastomers, such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization, are inevitably restricted by long-time usage, organic solvent additives, high energy consumption, and environmental pollution. Here, we propose a Joule heating chemistry method for ultrafast universal fabrication of SEs with configurable porous structures and tunable components (e.g., graphene, Ag, graphene oxide, TiO2, ZnO, Fe3O4, V2O5, MoS2, BN, g-C3N4, BaCO3, CuI, BaTiO3, polyvinylidene fluoride, cellulose, styrene-butadiene rubber, montmorillonite, and EuDySrAlSiOx) within seconds by only employing H2O as the solvent. The intrinsic dynamics of the in situ polymerization and porosity creation of these SEs have been widely investigated. Notably, a flexible capacitive sensor made from as-fabricated silicone-based elastomers exhibits a wide pressure range, fast responses, long-term durability, extreme operating temperatures, and outstanding applicability in various media, and a wireless human-machine interaction system used for rescue activities in extreme conditions is established, which paves the way for more polymer-based material synthesis and wider applications. [ABSTRACT FROM AUTHOR]

The development of advanced layered Ni-rich cathodes is essential for high-energy lithium-ion batteries (LIBs). However, the prevalent Ni-rich cathodes are still plagued by inherent issues of chemomechanical and thermal instabilities and limited cycle life. For this, here, we introduce an efficient approach combining single-crystalline (SC) design with in situ high-entropy (HE) doping to engineer an ultrahigh-Ni cobalt-free layered cathode of LiNi0.88Mn0.03Mg0.02Fe0.02Ti0.02Mo0.02Nb0.01O2 (denoted as HE-SC-N88). Thanks to the SC- and HE-doping merits, HE-SC-N88 is featured with a grain-boundary-free and stabilized structure with minimal lattice strain, preventing mechanical degradation, reducing surface parasitic reactions, and mitigating oxygen loss. Accordingly, our HESC-N88 cathode demonstrates exceptional electrochemical properties particularly with prolonged cycling stability under strenuous conditions in both half and full cells, and the delayed O loss-induced phase transitions upon heating. More meaningfully, our design of HE doping in redefining the ultrahigh-Ni Co-free SC cathodes will make a tremendous progress toward industrial application of next-generation LIBs. [ABSTRACT FROM AUTHOR]

The manipulation of stress in high-capacity microscale alloying anode materials, which undergo significant volumetric variation during cycling, is crucial prerequisite for improved their cycling capability. In this work, an innovative structural design strategy is proposed for scalable fabrication of a unique 3D highly porous micro structured germanium (Ge) featuring micro-nano hierarchical architecture as viable anode for high-performance lithium-ion batteries (LIBs). The resultant micro-sized Ge, consisting of interconnected nanoligaments and bicontinuous nanopores, is endowed with high activity, decreased Li+ diffusion distance and alleviated volume variation, appealing as an ideal platform for in-depth understanding the relationship between structural design and stress evolution. Such a micro-sized Ge being highly porous delivers a record high initial Coulombic efficiency of 92.5%, large volumetric capacity of 2,421 mAh cm-3 at 1.2 mA cm-2, exceptional rate capability (805.6 mAh g-1 at 10 Ag-11) and cycling stability (over 90% capacity retention after 1000 cycles even at 5 A g-1), largely outperforming the reported Ge-based anodes for LIBs. Furthermore, its underlying Li storage mechanism and stress dispersion behavior are explicitly revealed by combined substantial in situ/ex situ experimental characterizations and theoretical computation. This work provides novel insights into the rational design of high-performance and durable alloying anodes toward high-energy LIBs. [ABSTRACT FROM AUTHOR]

For the directional solidification repair of blade damage in an aviation turbine, a directional-growth repair layer on the surface of a nickel-based superalloy was prepared using an Nd:YAG laser. The microstructure of the directional-growth repair layer was investigated using scanning electron microscopy and transmission electron microscopy. Its phase composition and corrosion resistance were also analyzed and tested. The results indicate that the grains in the repair zone solidified in the same direction as the substrate and formed continuous columnar crystals, which were arranged in an orderly manner. A small number of secondary dendritic cells were dispersed in the transverse direction of the columnar crystals. The phase composition was mainly composed of the α′-based phase, β-precipitated strengthening phase, MC carbide, and interdendritic α′/β eutectic phase. The corrosion kinetic curve of the repair zone changed linearly. The oxide film was uniform and dense, and was mainly composed of continuous granular oxide. The corrosion kinetic curve of the substrate conformed to the parabolic law. The oxide film was composed of loose and bulky granular grains, which were stacked in the shape of regular polyhedra and distributed in the form of an island. [ABSTRACT FROM AUTHOR]

All-climate temperature operation capability and increased energy density have been recognized as two crucial targets, but they are rarely achieved together in rechargeable lithium (Li) batteries. Herein, we demonstrate an electrolyte system by using monodentate dibutyl ether with both low melting and high boiling points as the sole solvent. Its weak solvation endows an aggregate solvation structure and low solubility toward polysulfide species in a relatively low electrolyte concentration (2 mol L−1). These features were found to be vital in avoiding dendrite growth and enabling Li metal Coulombic efficiencies of 99.0%, 98.2%, and 98.7% at 23 °C, −40 °C, and 50 °C, respectively. Pouch cells employing thin Li metal (50 μm) and high-loading sulfurized polyacrylonitrile (3.3 mAh cm−2) cathodes (negative-to-positive capacity ratio = 2) output 87.5% and 115.9% of their room temperature capacity at −40 °C and 50 °C, respectively. This work provides solvent-based design criteria for a wide temperature range Li-sulfur pouch cells. [ABSTRACT FROM AUTHOR]

The doping of Al into layered Li transition metal (TM) oxide cathode materials, LiTMO2, is known to improve the structural and thermal stability, although the origin of the enhanced properties is not well understood. The effect of aluminum doping on layer stabilization has been investigated using a combination of techniques to measure the aluminum distribution in layered LiNi0.8Co0.15Al0.05O2 (NCA) over multiple length scales with 27Al and 7Li MAS NMR, local electrode atom probe (APT) tomography, X-ray and neutron diffraction, DFT, and SQUID magnetic susceptibility measurements. APT ion maps show a homogeneous distribution of Ni, Co, Al, and O2 throughout the structure at the single particle level in agreement with the high-temperature phase diagram. 7Li and 27Al NMR indicates that the Ni3+ ions undergo a dynamic Jahn-Teller (JT) distortion. 27Al NMR spectra indicate that the Al reduces the strain associated with the JT distortion, by preferential electronic ordering of the JT lengthened bonds directed toward the Al3+ ion. The ability to understand the complex atomic and orbital ordering around Al3+ demonstrated in the current method will be useful for studying the local environment of Al3+ in a range of transition metal oxide battery materials. [ABSTRACT FROM AUTHOR]