230 research outputs found
Mechanisms of Significant Precipitation Hardening in a Medium Carbon Bainitic Steel by Complex Nanocarbides Composed of Nb, Ti and V
Precipitation-hardening behavior of various medium carbon bainitic steels with added elements of Nb, Ti and V was systematically investigated. Complex nanocarbides composed of Nb, Ti and V precipitated after aging in the steel with multiple additions of all the elements, whereas those with added individual elements were simple MC types. The amount of precipitation hardening (ΔHv) after aging at 873 K of the former steel was approximately 90 ΔHv, while those of the latter were less than 40 ΔHv at best. Therefore, significant precipitation hardening took place by multiple element addition. The different amount of precipitation hardening depending on added elements was reasonably understood by considering misfit parameters between carbides and ferrite matrix
Ecdysone-dependent and ecdysone-independent programmed cell death in the developing optic lobe of Drosophila
AbstractThe adult optic lobe of Drosophila develops from the primordium during metamorphosis from mid-3rd larval stage to adult. Many cells die during development of the optic lobe with a peak of the number of dying cells at 24h after puparium formation (h APF). Dying cells were observed in spatio-temporal specific clusters. Here, we analyzed the function of a component of the insect steroid hormone receptor, EcR, in this cell death. We examined expression patterns of two EcR isoforms, EcR-A and EcR-B1, in the optic lobe. Expression of each isoform altered during development in isoform-specific manner. EcR-B1 was not expressed in optic lobe neurons from 0 to 6h APF, but was expressed between 9 and 48h APF and then disappeared by 60h APF. In each cortex, its expression was stronger in older glia-ensheathed neurons than in younger ones. EcR-B1 was also expressed in some types of glia. EcR-A was expressed in optic lobe neurons and many types of glia from 0 to 60h APF in a different pattern from EcR-B1. Then, we genetically analyzed EcR function in the optic lobe cell death. At 0h APF, the optic lobe cell death was independent of any EcR isoforms. In contrast, EcR-B1 was required for most optic lobe cell death after 24h APF. It was suggested that cell death cell-autonomously required EcR-B1 expressed after puparium formation. βFTZ-F1 was also involved in cell death in many dying-cell clusters, but not in some of them at 24h APF. Altogether, the optic lobe cell death occurred in ecdysone-independent manner at prepupal stage and ecdysone-dependent manner after 24h APF. The acquisition of ecdysone-dependence was not directly correlated with the initiation or increase of EcR-B1 expression
Data-driven Exploration of New Pressure-induced Superconductivity in PbBiTe with Two Transition Temperatures
Candidates compounds for new thermoelectric and superconducting materials,
which have narrow band gap and flat bands near band edges, were exhaustively
searched by the high-throughput first-principles calculation from an inorganic
materials database named AtomWork. We focused on PbBiTe which has the
similar electronic band structure and the same crystal structure with those of
a pressure-induced superconductor SnBi2Se4 explored by the same data-driven
approach. The PbBiTe was successfully synthesized as single crystals
using a melt and slow cooling method. The core level X-ray photoelectron
spectroscopy analysis revealed Pb2+, Bi3+ and Te2- valence states in
PbBiTe. The thermoelectric properties of the PbBiTe sample were
measured at ambient pressure and the electrical resistivity was also evaluated
under high pressure using a diamond anvil cell with boron-doped diamond
electrodes. The resistivity decreased with increase of the pressure, and two
pressure-induced superconducting transitions were discovered at 3.4 K under
13.3 GPa and at 8.4 K under 21.7 GPa. The data-driven approach shows promising
power to accelerate the discovery of new thermoelectric and superconducting
materials
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