Publication1

In this study, silver oxide nanoparticles (Ag2O-NPs) were synthesized from silver nitrate using green amaranth leaf extract as a reducing agent. The degradation of caffeine and inactivation of Escherichia coli (E. coli) by Ag2O-NPs was studied under compact fluorescent lamp illumination irradiation. Apart from that, the antibacterial and antioxidant activities of Ag2O-NPs were also examined. Synthesized Ag2O-NPs were shaped like monodispersed husk, and cubic structured with surface area, and average particle size was detected to be 100.21 (m2/g) and 81 nm, respectively. Antioxidant efficacy of the Ag2O-NPs was evaluated using 1, 1-diphenyl-2-picrylhydrazyl, and 91% inhibition was achieved with 100 µg Ag2O-NPs. Cell viability assay demonstrated that Ag2O-NPs showed less cytotoxicity for human embryonic kidney (HEK 293) cells. The bacteriocidic propensity of Ag2O-NPs was examined against the S. aureus and P. aeruginosa by disk diffusion, minimum inhibitory concentration (MIC), live and dead assay. It was observed that the NPs have a higher bactericidal effect on Gram-negative as compared to Gram-positive bacteria. Up to 96%, photocatalytic inactivation of E. coli was achieved using 30 µg/mL of NPs. Photocatalytic degradation of caffeine (50 ppm initial concentration) was observed to be 99% at pH 9 in 15 h using 50 mg/L of Ag2O NPs. These results indicate that Ag2O NPs can be employed in environmental applications like harmful bacteria inactivation and organic pollutants degradation. Graphic abstract: [Figure not available: see fulltext.]

Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport, particle deposition, coating, surface patterning, etc. Stability of nanofluid is vital for their use in these industrial applications, although the pertinent database in the literature is often inadequate. Herein, we investigate the effect of surfactant concentration and particle solid volume fraction (φ) on stability of Ti- and Al-oxide nanoparticle suspensions that are stabilized with different surfactants. While TiO2-AA, TiO2-CTAB nanofluids are found to have appreciable stability, SDBS-stabilized Al2O3 nanofluid shows otherwise. TEM images provide the morphological characteristics of freshly prepared nanofluids, whereas the data of DLS and ZP are used to describe the nanofluid particle size distribution and stability, respectively. SANS data confirm the formation of the different sized particles for all the nanofluids. Surface tension (ST) and contact angle (CA) of the prepared nanofluids have also been reported. Results show that the sessile droplet CA of a surfacted-water solutions decreases as more and more nanoparticles are added in the suspension. ST measurements corroborate with the CA measurements, where the nanofluid ST is found to decrease with increase in solid volume fraction (φ) and temperature. Time-lapse images indicate that the settling behaviour of Al2O3-water nanofluids changes with φ and surfactant ratios, but the TiO2-water nanofluids show consistent stability for all φ and surfactant ratios. The reported trend of variation of the mean deposition fraction per unit time with φ for different surfactant ratios helps in making better choice of surfactant ratio for individual φ.

Background: Neuromyelitis optica spectrum disorder (NMOSD), an autoimmune astrocytopathy, may share common clinico-radiological features with Wernicke's encephalopathy (WE). A variant of NMOSD, known as area postrema syndrome (APS), that presents with intractable hiccups and associated vomiting, might lead to the depletion of nutrients if not detected and treated early. Autoimmune thyroid disorders (i.e., Graves’ disease) may be associated with NMOSD. Rarely, thyrotoxicosis can give rise to thiamine depletion and WE. Case presentation: Here, we present a case of untreated hyperthyroidism in an Indian female who presented with thyrotoxicosis and later developed WE, possibly also contributed by NMOSD (APS)-induced recurrent vomiting. The patient recovered with antithyroid drugs, parenteral thiamine, and immunomodulatory therapy. The possible pathogenic mechanisms have been discussed. Conclusion: Our case establishes the importance of considering NMOSD variants in metabolic encephalopathy, especially if neuroimaging is suggestive and in the backdrop of another autoimmune disorder.

The importance of the axial catalyst holdup on the accurate prediction of reaction yields from Fluidized Catalytic Cracking Unit (FCCU) risers was explored in this study. The Kunii and Levenspiel model was incorporated in the FCCU riser simulations for predicting the solid holdup. Two approaches were compared-the popular one assuming Constant Holdup (CH) and the other incorporating Variable Holdup (VH) in the reaction kinetics models. Simulation predictions using these two approaches were fitted to the yield profiles obtained from industrial plant data reported in the literature. The kinetic parameter estimates, including frequency factors and coking parameters obtained from these two approaches, were quite similar, indicating insensitivity to catalyst holdup. However, the kinetic model incorporating VH expression could predict the plant conversion and yield to within ±10% error throughout the riser. In contrast, the CH model led to predictions that were rather erroneous (>±25%) at the riser bottom as the catalyst particle acceleration zone was neglected. Temperature, gas density, catalyst particle, and gas phase velocity profiles obtained from the VH approach were considerably different from those obtained using the CH approach. The VH approach showed that the slip factor, especially, was quite distinct as it reached a peak value before decaying exponentially. On the other hand, the CH model showed a monotonic increase in slip factor along the riser.

Research on the air flow disturbances in the aircraft carrier environment has gained prominence in recent times. However, there is presently no representative carrier model analogous to the Simplified Frigate Shape (SFS) which is generic naval frigate for air flow investigation. In the present study, a Generic Aircraft Carrier (GAC) model is proposed, as a simplified, benchmark model for aerodynamic research. With the motivation to provide validation data for future CFD studies, baseline experimental data is generated in the wind tunnel, in terms of pressure distribution over the deck, for two variants, namely, a complete flat deck configuration with no island and secondly, with the island in the baseline position of the GAC. Effect of the island in modifying the flow is discussed by a comparison between the two variants. Particle Image Velocimetry (PIV) is employed to record velocity and turbulence levels in the GAC environment, highlighting regions of velocity deficits, and unsteady flow which may hinder the landing procedure of an approaching pilot. Comprehensive database of experimental data is presented as baseline data for future work and for validation of numerical models. Traditional tuft and smoke visualization studies are also conducted to provide corroboratory qualitative insights.