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The major drawback of zirconia-based materials, in view of their applications as targets for minor actinide transmutation, is their poor thermal conductivity. The addition of MgO, which has high thermal conductivity, to zirconia-based materials is expected to improve their thermal conductivity. On these grounds, the present study aims at phase characterization and thermophysical property evaluation of neodymium-substituted zirconia (Zr0.8Nd0.2O1.9; using Nd2O3 as a surrogate for Am2O3) and its composites with MgO. The composite was prepared by a solid-state reaction of Zr0.8Nd0.2O1.9 (synthesized by gel combustion) and commercial MgO powders at 1773 K. Phase characterization was carried out by X-ray diffraction and the microstructural investigation was performed using a scanning electron microscope equipped with energy dispersive spectroscopy. The linear thermal expansion coefficient of Zr0.8Nd0.2O1.9 increases upon composite formation with MgO, which is attributed to a higher thermal expansivity of MgO. Similarly, specific heat also increases with the addition of MgO to Zr0.8Nd0.2O1.9. Thermal conductivity was calculated from measured thermal diffusivity, temperature-dependent density and specific heat values. Thermal conductivity of Zr0.8Nd0.2O1.9–MgO (50 wt%) composite is more than that of typical UO2 fuel, supporting the potential of Zr0.8Nd0.2O1.9–MgO composites as target materials for minor actinides transmutation.

This is the first study undertaken towards development of mixed-matrix membranes (MMMs) with enhanced radiation resistant attributes by reinforcement of nanostructured Gd2Zr2O7 (GZO) within polysulfone (Psf) host-matrix. The study describes synthesis and characterization of GZO in disordered, defect-fluorite structure, having average crystallite size of 31(±3) nm. Membranes prepared with different loading of GZO (up to 2 w/w% of Psf) are exposed to γ-radiation up to a dose of 1000 kGy in aqueous environment. The effect of radiation on the structural, mechanical, and thermo-oxidative properties of MMMs has been compared with that of radiation-sensitive Psf membrane. The ultrafiltration performance of the (un)irradiated Psf and MMMs reveal that an optimum reinforcement of GZO at 1 (w/wPsf)% offers ~10 times radiation resistant MMM, compared to that of Psf membrane. The MMM with 1 (w/wPsf)% GZO was rolled into 2512 spiral configuration and a highly-compact device was developed for treatment of radioactive effluent. Based on the flux decline behaviour over 18 months duration, the fouling behaviour of the MMM module was modelled. The life-span of the MMM was predicted based on the absorbed radiation dose, GZO leaching study, and fouling behaviour. It is proposed that GZO mitigates a fraction of the impinged γ-energy in swapping of the Gd3+ and Zr4+ sites, which protects the polymeric host-matrix in-situ from radiation induced degradation. The abundance of Gd3+ and Zr4+ associated with polar O2− over the impregnated GZO further stabilizes MMMs through scavenging of the oxidizing and reducing radiolysed products of water. Thus, we report a smart approach to develop novel MMM with greater life-expectancy against high-energy radiation and further fabricate a membrane-based device for management of liquid radioactive waste.

Summary: We report an unusual case of varicella zoster in a 19-year-old, who presented with persisting fever even after her lesions began forming scabs. Fever workup for secondary complications was negative. A re-examination revealed an axillary eschar. She recovered completely with doxycycline. This report suggests the importance of keeping in mind, epidemiological data of common diseases in the locality, as well as the significance of a thorough physical examination in patients with fever. Keywords: Scrub typhus co-infection, Rickettsial rash, Varicella zoster