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The Chinese CubeSat Mission, Gamma Ray Integrated Detectors (GRID), recently detected its first gamma-ray burst, GRB 210121A, which was jointly observed by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM). This burst is confirmed by several other missions, including Fermi and Insight-HXMT. We combined multimission observational data and performed a comprehensive analysis of the burst’s temporal and spectral properties. Our results show that the burst is relatively special in its high peak energy, thermal-like low-energy indices, and large fluence. By putting it to the E p –E γ,iso relation diagram with assumed distance, we found that this burst can be constrained at the redshift range of [0.3, 3.0]. The thermal spectral component is also confirmed by the direct fit of the physical models to the observed spectra. Interestingly, the physical photosphere model also constrained a redshift of z ∼ 0.3 for this burst, which helps us to identify a host galaxy candidate at such a distance within the location error box. Assuming that the host galaxy is real, we found that the burst can be best explained by the photosphere emission of a typical fireball with an initial radius of r 0 ∼ 3.2 × 107 cm.

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Ultralong, polycrystalline Ni2Si nanowires are fabricated by combining sidewall transfer lithography with self-aligned silicidation. Upon formation at 500°C, the nanowires that are 400μm long with a rectangular cross section of 37.5 by 25.3nm are characterized by a resistivity of 25±1μΩcm which is similar to the value for Ni2Si thin films. Further annealing at 800°C results in an extraordinarily low wire resistivity of 10μΩcm. Such a drastic decrease in resistivity is attributed to a significant grain growth and a low density of defects in the nanowires.

The structures of the CaO-P 2 O 5 -SiO 2 slag system with varying P 2 O 5 /SiO 2 ratios at a fixed CaO content have been investigated by molecular dynamics simulation using the pairwise potential model. The results showed that the average bond lengths of Si-O and P-O were 1.610 « 0.001 ¡ and 1.531 « 0.005 ¡ in the examined range of the P 2 O 5 /SiO 2 ratio. More than 95% Si and P ions were 4-coordinated and formed tetrahedral structures. Average coordination numbers of P-O and Si-O decreased slightly while average coordination number of Ca-O revealed a rising trend with the addition of P 2 O 5 . The non-bridging oxygens (Si-O-Ca and P-O-Ca) were the overwhelming majority and further increased with the substitution of SiO 2 by P 2 O 5 , which results in the decrease of the polymerization constant K p . The numbers of Si and P groups linked to a tagged Si or P tetrahedron (Q n speciation) characterized the polymerization degree of the slag system. The Q 0 of both P and Si declined remarkably with the increase of P 2 O 5 . Correspondingly, () of Si and P increased observably, implying that the polymerization degree of the slag system was enhanced.

Magnesium, the lightest structural metal, usually exhibits limited ambient plasticity when compressed along its crystallographic c-axis (the “hard” orientation of magnesium). Here we report large plasticity in c-axis compression of submicron magnesium single crystal achieved by a dual-stage deformation. We show that when the plastic flow gradually strain-hardens the magnesium crystal to gigapascal level, at which point dislocation mediated plasticity is nearly exhausted, the sample instantly pancakes without fracture, accompanying a conversion of the initial single crystal into multiple grains that roughly share a common rotation axis. Atomic-scale characterization, crystallographic analyses and molecular dynamics simulations indicate that the new grains can form via transformation of pyramidal to basal planes. We categorize this grain formation as “deformation graining”. The formation of new grains rejuvenates massive dislocation slip and deformation twinning to enable large plastic strains.

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