Browsing by Author "Mishra, R.K."

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Functionalizable 1H-Indazoles by Palladium Catalyzed Aza-Nenitzescu Reaction: Pharmacophores to Donor-Acceptor Type Multi-Luminescent Fluorophores
(2018) Janardhanan, J.C.; Mishra, R.K.; Das, G.; Sini, S.; Jayamurthy, P.; Suresh, C.H.; Praveen, V.K.; Manoj, N.; Babu, B.P.
Development of small-molecule-based multi-luminescent fluorophores utilizing simple synthetic methodologies, as well as easily available starting materials, has gained much attention in recent years. Herein, we disclose an efficient protocol for the synthesis of N-protected 1H-indazole derivatives with diverse substituents at their 3- and 5-positions via palladium-catalyzed reactions of hydrazones and p-benzoquinones. The obtained 1H-indazole derivatives can be easily modified into donor-acceptor (D?A)-type chromophores (Indazo-Fluors) with tunable emission properties in both solid and solution state. Owing to the extent of intramolecular charge transfer, Indazo-Fluors exhibit positive solvatochromic emission spanning from blue-green to orange-red. Theoretical studies were undertaken to rationalize the observed trends in the optical properties of Indazo-Fluors. Finally, a triethylene glycol (TEG) appended Indazo-Fluor exhibiting a large Stokes shift and low cytotoxicity allowed us to use it for cell imaging. 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Functionalizable 1H-Indazoles by Palladium Catalyzed Aza-Nenitzescu Reaction: Pharmacophores to Donor-Acceptor Type Multi-Luminescent Fluorophores
(Wiley-VCH Verlag info@wiley-vch.de, 2018) Janardhanan, J.C.; Mishra, R.K.; Das, G.; Sini, S.; Jayamurthy, P.; Suresh, C.H.; Praveen, V.K.; Manoj, N.; Babu, B.P.
Development of small-molecule-based multi-luminescent fluorophores utilizing simple synthetic methodologies, as well as easily available starting materials, has gained much attention in recent years. Herein, we disclose an efficient protocol for the synthesis of N-protected 1H-indazole derivatives with diverse substituents at their 3- and 5-positions via palladium-catalyzed reactions of hydrazones and p-benzoquinones. The obtained 1H-indazole derivatives can be easily modified into donor-acceptor (D?A)-type chromophores (Indazo-Fluors) with tunable emission properties in both solid and solution state. Owing to the extent of intramolecular charge transfer, Indazo-Fluors exhibit positive solvatochromic emission spanning from blue-green to orange-red. Theoretical studies were undertaken to rationalize the observed trends in the optical properties of Indazo-Fluors. Finally, a triethylene glycol (TEG) appended Indazo-Fluor exhibiting a large Stokes shift and low cytotoxicity allowed us to use it for cell imaging. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Tribological Behaviour of Graphite-Reinforced FeNiCrCuMo High-Entropy Alloy Self-Lubricating Composites for Aircraft Braking Energy Applications
(2019) Prabhu, T.R.; Arivarasu, M.; Chodancar, Y.; Arivazhagan, N.; Sumanth, G.; Mishra, R.K.
In the present study, the graphite-reinforced FeNiCrCuMo high-entropy alloy-based self-lubricating composites are fabricated through the powder metallurgy. The sintering temperatures (900 and 1000��C) are varied to study the densification and properties of the composites. The composites are characterized for microstructure, density, and hardness. The brake performance of the composites is evaluated for the braking condition of a military aircraft. The microstructure consists of two phases: one phase (lamella structure) rich with the Fe, Cr, C, and Cu and another white phase rich with the Ni, Cu, C, and Fe along with the uniformly distributed graphite. The EDS analysis confirms the presence of Fe, Cr, Ni, Cu, and Mo in the matrix. The composite sintered at 1000��C shows improved densification, high hardness, high wear resistance, and excellent braking performance. With the increase of braking energy (speed), the wear rate increases due to the increased intensity of abrasive wear, oxidation wear, and plastic deformation-assisted wear, whereas the friction coefficient has not changed much. Low porosity content and mild abrasive wear are responsible for the high wear resistance in the composite sintered at 1000��C. Compared to the C/C, C/SiC C/C/SiC composites and Fe- or Cu-based composites, the high-entropy alloy-based composites show great potential for improved braking properties in the high-energy braking applications. � 2019, Springer Science+Business Media, LLC, part of Springer Nature.
Tribological Behaviour of Graphite-Reinforced FeNiCrCuMo High-Entropy Alloy Self-Lubricating Composites for Aircraft Braking Energy Applications
(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Prabhu, T.R.; Arivarasu, M.; Chodancar, Y.; Arivazhagan, N.; Cadambi, G.; Mishra, R.K.
In the present study, the graphite-reinforced FeNiCrCuMo high-entropy alloy-based self-lubricating composites are fabricated through the powder metallurgy. The sintering temperatures (900 and 1000 °C) are varied to study the densification and properties of the composites. The composites are characterized for microstructure, density, and hardness. The brake performance of the composites is evaluated for the braking condition of a military aircraft. The microstructure consists of two phases: one phase (lamella structure) rich with the Fe, Cr, C, and Cu and another white phase rich with the Ni, Cu, C, and Fe along with the uniformly distributed graphite. The EDS analysis confirms the presence of Fe, Cr, Ni, Cu, and Mo in the matrix. The composite sintered at 1000 °C shows improved densification, high hardness, high wear resistance, and excellent braking performance. With the increase of braking energy (speed), the wear rate increases due to the increased intensity of abrasive wear, oxidation wear, and plastic deformation-assisted wear, whereas the friction coefficient has not changed much. Low porosity content and mild abrasive wear are responsible for the high wear resistance in the composite sintered at 1000 °C. Compared to the C/C, C/SiC C/C/SiC composites and Fe- or Cu-based composites, the high-entropy alloy-based composites show great potential for improved braking properties in the high-energy braking applications. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.