Deep Prakash

Barium titanate microparticles as potential carrier platform for lanthanide radionuclides for their use in the treatment of arthritis

Since the inception of radiation synovectomy, a host of radioactive colloids and microparticles incorporating suitable therapeutic radionuclides have been proposed for the treatment of arthritis. The present article reports the synthesis and evaluation of barium titanate microparticles as an innovative and effective carrier platform for lanthanide radionuclides in the preparation of therapeutic agents for treatment of arthritis. The material was synthesized by mechanochemical route and characterized by X-ray diffraction, scanning electron microscopy, surface area, and particle size distribution analyses. Loading of lanthanide radionuclides (166 Ho, 153 Sm, 177 Lu, and 169 Er) on the microparticles was achieved in high yield (> 95%) resulting in the formulation of loaded particulates with excellent radiochemical purities (> 99%). Radiolanthanide-loaded microparticles exhibited excellent in vitro stability in human serum. In vitro diethylene triamine pentaacetic acid challenge study indicated fairly strong chemical association of lanthanides with barium titanate microparticles. Long-term biodistribution studies carried out after administration of 177 Lu-loaded microparticles into one of the knee joints of normal Wistar rats revealed near-complete retention of the formulation (> 96% of the administered radioactivity) within the joint cavity even 14 days post-administration. The excellent localization of the loaded microparticles was further confirmed by sequential whole-body radio-luminescence imaging studies carried out using 166 Ho-loaded microparticles.

Fabrication and testing of unileg oxide thermoelectric device

A prototype of oxide thermoelectric unileg device was fabricated. This device was based on only n-legs made of La doped calcium manganate. The powder was synthesized, characterised and consolidated in rectangular thermoelements. A 3×3 device was fabricated by fitting 9 rectangular bars in alumina housing and connected by silver strips. The device has been tested under large temperature difference (ΔT=480°C) using an indegenous system. An open circuit voltage of 468 mV was obtained for a nine leg ‘unileg’ device. The device exhibits a internal resistance of ∼1Ω. The maximum power output for this nine leg device reached upto 50 mW in these working condition.

Development of Ca-doped LaCr03 feed material and its plasma coating for SOFC applications

In order to realize SOFC as power generating devices, multiple cells are connected in series through an interconnect material to accumulate the voltage output. The interconnect should have very low permeability for the gases used. A novel solution combustion process has been developed for producing the phase pure, well-sinterable powders of Ca-doped LaCrO3 interconnect material. A process has been developed to produce the coarse granules as a feed material using combustion-synthesized powder for plasma spray through (a) preparation of granules through cold iso-static pressing followed by breaking and sieving (b) sintering of the green granules followed by sieving. The flow ability and deposition efficiency studies on +45-75 and 75-125 μm powders suggested that +45-75 powder is more suitable for the plasma spray coating. The plasma process parameters; plasma power, flow rate of carrier gases and distance between substrate and plasma gun have been optimized to achieve required coating characteristics. The as-produced coating using 20 kW power plasma gun on the porous Sr-doped LaMnO3 cathode substrates has been examined by SEM. An adherent coating of about 100 μm has been observed in the micrographs. No large cracks were observed throughout the coating. However, the coating was not found to be impervious in nature. Also the micrographs showed incomplete melting of the plasma-coated material. The similar experiments were performed using a higher power (≈ 60 Kw) plasma gun. The coated coupons were tested for leakage by checking water penetration. It was found that water did not penetrate for quite a long time. Therefore, the coupon was further tested for leakage by keeping it over a port connected to vacuum pump. The vacuum attained was 7×10-3 mbar and it was maintained for four consecutive days. The SEM studies on the coated sample showed a quite dense coating along with a very few small local pores.