Sustainable hydrogen production via LiH hydrolysis for unmanned air vehicle (UAV) applications

In the current study, an experimental approach for the further understanding of the LiH hydrolysis reaction for hydrogen production is considered. The experimental work has been undertaken under small scale conditions by utilising fixed bed reactors. The hydrolysis reaction has been studied at several oven temperatures (150 °C, 300 °C and 500 °C). The favourable driving potentials for the hydrolysis reactions were identified by the utilisation of the Gibbs free energy analysis. The main outcome of the study is the deceleration of the reaction pace due to the formation of the by-product layers during the reaction. At the initial stage, due to the contact of steam with the unreacted and fresh LiH surface, the reaction proceeds on a fast pace, while the formation of the layers tends to decelerate the diffusion of steam into the core of material, forcing the production step to be slower. The hydrogen yield was found to be more than 90% of the theoretical value for all the reaction temperatures. Finally, a scenario of a hybrid-electric propulsion system for Unmanned Aerial Vehicles (UAVs) including Li-ion battery, Proton Membrane Fuel Cell (PEMFC) and an on-board hydrogen production system based on LiH hydrolysis is introduced and studied

Management and outcomes of unilateral group d tumors in retinoblastoma

Purpose: Retinoblastoma presents most commonly as advanced unilateral disease, particularly in developing countries for which primary enucleation has been the preferred method of treatment. However, with the evolution of newer treatment modalities including intravitreal chemotherapy, intra-arterial chemotherapy and newer chemotherapeutic combinations, a trend towards more conservative approaches is being observed. Our aim is to evaluate outcomes of group D eyes following conservative and non-conservative treatment options. Patients and Methods: The ocular oncology database was used to identify eyes with unilateral retinoblastoma that fulfilled the International Intraocular Retinoblastoma Classification (IIRC) group D criteria from August 2010 to August 2018 and these were retrospectively reviewed. Overall, 39 eyes were identified. Results: Nineteen (49%) eyes underwent primary enucleation and 20 (51%) received eyeconserving treatment. Eye salvage was possible in 15 (75%) eyes in the attempted salvage group. None of the patient revealed signs of metastasis. All eyes received conventional chemotherapy (carboplatin, vincristine, etoposide) and focal laser therapy. Additional treatment modalities offered included intravitreal chemotherapy, intra-arterial chemotherapy and topotecan. Three (11%) eyes in the primary enucleation group showed high-risk features on histopathology and none developed metastasis. Conclusion: The results of the study seem promising and conservative measures can be adopted in selected unilateral group D eyes

Efficient hydrogen storage in up-scale metal hydride tanks as possible metal hydride compression agents equipped with aluminium extended surfaces

In the current work, a three-dimensional computational study regarding coupled heat and mass transfer during both the hydrogenation and dehydrogenation process in upscale cylindrical metal hydride reactors is presented, analysed and optimized. Three different heat management scenarios were examined at the degree to which they provide improved system performance. The three scenarios were: 1) plain embedded cooling/heating tubes, 2) transverse finned tubes and 3) longitudinal finned tubes. A detailed optimization study was presented leading to the selection of the optimized geometries. In addition, two different types of hydrides, LaNi5 and an AB2-type intermetallic were studied as possible candidate materials for using as the first stage alloys in a two-stage metal hydride hydrogen compression system. As extracted from the above results, it is clear that the case of using a vessel equipped with 16 longitudinal finned tubes is the most efficient way to enhance the hydrogenation kinetics when using both LaNi5 and the AB2-alloy as the hydride agents. When using LaNi5 as the operating hydride the case of the vessel equipped with 60 embedded cooling tubes presents the same kinetic behaviour with the case of the vessel equipped with 12 longitudinal finned tubes, so in that way, by using extended surfaces to enhance the heat exchange can reduce the total number of tubes from 60 to 12. For the case of using the AB2-type material as the operating hydride the performance of the extended surfaces is more dominant and effective compared to the case of using the embedded tubes, especially for the case of the longitudinal extended surfaces