Bioinspired Synthesis of Reduced Graphene Oxide-Wrapped Geobacter sulfurreducens as a Hybrid Electrocatalyst for Efficient Oxygen Evolution Reaction

Doping/decorating of graphene or reduced graphene oxide (rGO) with heteroatoms provides a promising route for the development of electrocatalysts which will be useful in many technologies, including water splitting. However, current doping approaches are complicated, not eco-friendly, and not cost-effective. Herein, we report the synthesis of doped/decorated rGO for oxygen evolution reaction (OER) using a simple approach that is cost-effective, sustainable, and easy to scale up. The OER catalyst was derived from the reduction of GO by an exo-electron-transferring bacterium, Geobacter sulfurreducens. Various analytical tools indicate that OER active elements such as Fe, Cu, N, P, and S decorate the rGO flakes. The hybrid catalyst (i.e., Geobacter/rGO) produces a geometric current density of 10 mA cm–2 at an overpotential of 270 mV versus the reversible hydrogen electrode with a Tafel slope of 43 mV dec–1 and possesses high durability, as evidenced through 10 h of stability testing. Electrochemical analyses suggest the importance of Fe and its possible role as an active site for OER. Overall, this work represents a simple approach toward the development of an earth-abundant, eco-friendly, and highly active OER electrocatalyst for various applications such as solar fuel production, rechargeable metal–air batteries, and microbial electrosynthesis

Roadmap on optical sensors

Optical sensors and sensing technologies are playing a more and more important role in our modern world. From micro-probes to large devices used in such diverse areas like medical diagnosis, defence, monitoring of industrial and environmental conditions, optics can be used in a variety of ways to achieve compact, low cost, stand-off sensing with extreme sensitivity and selectivity. Actually, the challenges to the design and functioning of an optical sensor for a particular application requires intimate knowledge of the optical, material, and environmental properties that can affect its performance. This roadmap on optical sensors addresses different technologies and application areas. It is constituted by twelve contributions authored by world-leading experts, providing insight into the current state-of-the-art and the challenges their respective fields face. Two articles address the area of optical fibre sensors, encompassing both conventional and specialty optical fibres. Several other articles are dedicated to laser-based sensors, micro- and nano-engineered sensors, whispering-gallery mode and plasmonic sensors. The use of optical sensors in chemical, biological and biomedical areas is discussed in some other papers. Different approaches required to satisfy applications at visible, infrared and THz spectral regions are also discussed

Design and syntheses of anisotropic metal nanostructures with tailored morphology for applications in electro-catalysis and surface enhanced raman scattering

The main goal of this thesis is to design and develop synthesis methods which enable the preparation of more efficient noble metal nanoparticles with tailored morphologies for optical, catalytic and SERS applications. In chapter 2, we demonstrate a two-step seed-mediated growth method to synthesize a new class of spiky Ag-Au octahedral nanoparticles with tunable spike length from 10 – 130 nm with sharp tips. Spatially resolved EELS study on individual spiky Ag-Au nanoparticles illustrates multipolar plasmonic responses. In chapter 3, we develop a one-step solution phase synthesis of tunable nanoporous gold (np-Au) nanoparticles and demonstrated their superior catalytic activity towards methanol electro-oxidation. Furthermore, we demonstrate a seed mediated route to synthesize morphology controlled np-Au nanoparticles (chapter 4) with reduced symmetry and ligament size control down to <6 nm. In the last chapter 5, we demonstrate np-Au nanoparticles with reduced symmetry, will hold intense electromagnetic fields exploitable for location dependent SERS on single np-Au nanoparticles under near-infrared excitation.DOCTOR OF PHILOSOPHY (SPMS

A Prospective Study on the Clinical Profile and Outcome of Meningoencephalitis in Adults in a South Indian Tertiary Care Centre

Background Although there are numerous studies on meningitis and encephalitis separately, literature on meningoencephalitis is sparse. In this study we analysed the clinical profile of meningoencephalitis and its clinical outcome. Methods Fifty adults diagnosed with meningoencephalitis from July 2014 to July 2015 in a tertiary care hospital in South India were studied prospectively and their clinical presentation, aetiology and outcome were analysed. Results Among 50 patients, 33 (66%) were male; 39 (78%) were &lt;50 years of age. Fever was the most common presenting symptom in 41 out of 50 patients (82%), followed by headache (74%) and altered sensorium (62%); only 18 patients (36%) had all three classical symptoms. Twenty-eight out of 50 patients (56%) did not have neck stiffness. A majority of patients had acute-to-subacute clinical presentation. Mycobacterium tuberculosis was identified in 58% (29 out of 50). Forty-seven patients (94%) recovered completely. Conclusion Tuberculosis was the most common cause of meningoencephalitis in the studied population, often with subacute presentation, and outcome was good with early institution of antituberculous therapy. </jats:sec

Effect of Nano-urea on Growth, Productivity and Economics of Transplanted Rice

A field experiment was conducted during July to November of 2021 to assess the effect of nano-urea on growth and productivity of rice at ICAR-Indian Institute of Rice Research, Hyderabad, Telangana State, India. The experiment was laid out in randomized complete block design consisting eight treatments viz., Recommended dose of nitrogen (RDN) through urea (T1), 50% of RDN (urea)+two foliar sprays of nano-urea @ 0.2% at Active tillering (AT) and Panicle initiation (PI) stages (T2), 75% of RDN+two foliar sprays of nano-urea @ 0.2% at AT and PI (T3), 50% of RDN+two foliar sprays of nano-urea @ 0.4%  at (AT and PI) (T4), 75% of RDN+two foliar sprays of nano-urea @ 0.4% at AT and PI (T5), 25% of RDN+Four foliar sprays of nano-urea @ 0.2% at 20,33,50 and 65 DAT (T6), 25% of RDN+Four foliar sprays of nano-urea @ 0.4% 20,33,50 and 65 DAT (T7) and control (no fertilizer application) (T8). Results showed that foliar spray of nano-urea resulted in higher plant height (120.1 cm), tillers number m-2 (265) and dry matter accumulation (741.9 kg ha-1). Yield attributes viz., panicle number m-2, number of grains panicle-1, number of filled grains panicle-1 were significantly influenced by the application of nano-urea. The highest grain yield (5.39 t ha-1) and straw yield (6.73 t ha-1) was recorded with the application of 75% of RDN+two foliar sprays of nano-urea @ 0.4% at AT and PI stages. The application of nano-urea resulted in saving of nitrogen (urea) to an extent of 25%