Elastic Moduli of Nanoglasses and Melt-Spun Metallic Glasses by Ultrasonic Time-of-Flight Measurements

The elastic moduli of the metallic nanoglasses Fe$_{86}$Sc$_{14}$, Fe$_{90}$Sc$_{10}$, Cu$_{58}$Zr$_{42}$, and Cu$_{60}$Zr$_{40}$ were determined by measuring their longitudinal and shear wave velocities together with their densities. The data were compared to the elastic moduli of the conventional meltspun metallic glass counterparts of the same chemical composition. The elastic moduli for the nanoglasses were significantly smaller than those of the metallic glass counterparts. Finally, a comparison was made between the data for nanoglasses and metallic glasses from the literature

Elastic Moduli of Nanoglasses and Melt-Spun Metallic Glasses by Ultrasonic Time-of-Flight Measurements

The elastic moduli of the metallic nanoglasses Fe86Sc14, Fe90Sc10, Cu58Zr42, and Cu60Zr40 were determined by measuring their longitudinal and shear wave velocities together with their densities. The data were compared to the elastic moduli of the conventional melt-spun metallic glass counterparts of the same chemical composition. The elastic moduli for the nanoglasses were significantly smaller than those of the metallic glass counterparts. Finally, a comparison was made between the data for nanoglasses and metallic glasses from the literature

Norepinephrine directly activates adult hippocampal precursors via beta(3)-adrenergic receptors

Adult hippocampal neurogenesis is a critical form of cellular plasticity that is greatly influenced by neural activity. Among the neurotransmitters that are widely implicated in regulating this process are serotonin and norepinephrine, levels of which are modulated by stress, depression and clinical antidepressants. However, studies to date have failed to address a direct role for either neurotransmitter in regulating hippocampal precursor activity. Here we show that norepinephrine but not serotonin directly activates self-renewing and multipotent neural precursors, including stem cells, from the hippocampus of adult mice. Mechanistically, we provide evidence that beta(3)-adrenergic receptors, which are preferentially expressed on a Hes5-expressing precursor population in the subgranular zone (SGZ), mediate this norepinephrine-dependent activation. Moreover, intrahippocampal injection of a selective beta(3)-adrenergic receptor agonist in vivo increases the number of proliferating cells in the SGZ. Similarly, systemic injection of the beta-adrenergic receptor agonist isoproterenol not only results in enhancement of proliferation in the SGZ but also leads to an increase in the percentage of nestin/glial fibrillary acidic protein double-positive neural precursors in vivo. Finally, using a novel ex vivo "slice-sphere" assay that maintains an intact neurogenic niche, we demonstrate that antidepressants that selectively block the reuptake of norepinephrine, but not serotonin, robustly increase hippocampal precursor activity via beta-adrenergic receptors. These findings suggest that the activation of neurogenic precursors and stem cells via beta(3)-adrenergic receptors could be a potent mechanism to increase neuronal production, providing a putative target for the development of novel antidepressants

Nanoglass–Nanocrystal Composite - a Novel Material Class for Enhanced Strength–Plasticity Synergy

The properties of a material can be engineered by manipulating its atomic and chemical architecture. Nanoglasses which have been recently invented and comprise nanosized glassy particles separated by amorphous interfaces, have shown promising properties. A potential way to exploit the structural benefits of nanoglasses and of nanocrystalline materials is to optimize the composition to obtain crystals forming within the glassy particles. Here, a metastable Fe‐10 at% Sc nanoglass is synthesized. A complex hierarchical microstructure is evidenced experimentally at the atomic scale. This bulk material comprises grains of a Fe$_{90}$Sc$_{10}$ amorphous matrix separated by an amorphous interfacial network enriched and likely stabilized by hydrogen, and property‐enhancing pure‐Fe nanocrystals self‐assembled within the matrix. This composite structure leads a yield strength above 2.5 GPa with an exceptional quasi‐homogeneous plastic flow of more than 60% in compression. This work opens new pathways to design materials with even superior properties