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The spheroidization behavior of the dendritic b.c.c. phase dispersed in a bulk metallic glass (BMG) matrix was investigated through applying semi-solid isothermal processing and a subsequent rapid quenching procedure to a Zr-based β-phase composite. The Zr-based composite with the composition of Zr56.2Ti13.8Nb5.0Cu6.9Ni5.6 Be12.5 was prefabricated by a water-cooled copper mold-casting method and characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the composite consists of a glassy matrix and uniformly distributed fine dendrites of the β-Zr solid solution with the body-centered-cubic (b.c.c.) structure. Based on the differential scanning calorimeter (DSC) examination results, and in view of the b.c.c. β-Zr to h.c.p. α-Zr phase transition temperature, a semi-solid holding temperature of 900 ºC was determined. After reheating the prefabricated composite to the semi-solid temperature, followed by an isothermal holding process at this temperature for 5 min, and then quenching the semi-solid mixture into iced-water; the two-phase microstructure composed of a BMG matrix and uniformly dispersed spherical b.c.c. β-Zr particles with a high degree of sphericity was achieved. The present spheroidization transition is a thermodynamically autonomic behavior, and essentially a diffusion process controlled by kinetic factors; and the formation of the BMG matrix should be attributed to the rapid quenching of the semi-solid mixture as well as the large glass-forming ability of the remaining melt in the semi-solid mixture. [ABSTRACT FROM AUTHOR]

A liquid chromatography−mass spectrometry method was developed for the simultaneous quantitation of (2R,3R)-Dihydromyricetin and Myricetin in rat plasma samples to facilitate analysis of samples collected after administration of SenDeng-4 medicine. The plasma was subjected to protein precipitation with HCl (containing 10% ascorbic acid) and analyzed using electrospray ionization mass spectrometry in selected ion monitoring mode with Paeoniflorin as an internal standard. Good linearity for the two compounds was observed. The intra- and inter-day precision of analysis was <10% for each compound. The present method was suitable for determining (2R,3R)-Dihydromyricetin and Myricetin in rat plasma after intravenous administration of SenDeng-4 to rats with sufficient sensitivity. [ABSTRACT FROM AUTHOR]

Microwave absorbers have been applied extensively to attenuate harmful electromagnetic radiation. In this study, efficient microwave absorbers are successfully prepared using metal-organic frameworks as precursors through a convenient in-situ growth and selenization approach in which NiSe nanoparticles are embedded in rod-like carbon networks decorated with graphitic carbon bubbles. The chemical composition, microstructure, graphitization degree, and corresponding microwave absorption performance are well controlled by changing the selenization condition. Remarkably, the reflection loss of the NiSe/C composite obtained at 700 °C reached −59.70 dB at 7.89 GHz and the effective absorption bandwidth was 4.67 GHz. In the as-prepared composite, pervasive carbon networks help improve conductive loss. The homogeneous interfaces between metal selenides and carbon, as well as the abundant defects and interfaces in the graphitic carbon bubbles, boost interfacial polarization and accelerate electron transfer, contributing to the high-performance absorption. [ABSTRACT FROM AUTHOR]