Browsing by Author "Sharma, J."

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Catalytic Synthesis of Xanthene and Unprecedented Evolution of Naphthopyrans Using Heteropoly Acid-Tantalum(V) Oxide Hybrid Composite as Promoter
(John Wiley and Sons Inc, 2025) Mahapatra, J.; Dastidar, S.G.; Jagankar, D.; Roy, N.; Sharma, J.; Mukherjee, A.; Maity, C.; Panda, T.K.; Mal, S.S.
Xanthene derivatives are prepared by using tantalum(V) oxide (Ta2O5)-supported heteropoly acid (HPA), Keggin 12-phosphotungstic acid (PTA)-based heterogeneous catalyst PTA@Ta2O5 under neat conditions. The composite is prepared by the wetness impregnation method and is characterized by various techniques. Under optimized conditions, xanthenes are synthesized with prominent yields in remarkably short reaction times. The green chemistry metrics are appraised for the xanthene reaction. Surprisingly, a few novel naphthopyran derivatives are isolated instead of the conventional xanthene derivatives when cinnamaldehyde analogous are introduced under the same reaction protocol. Unprecedented naphtho[2,1-b]pyran-type derivatives of 3m, 3n, and 3o are isolated, depending on the specific substituted cinnamaldehyde used, and interestingly, the nature of the substituent in cinnamaldehyde decides the different reaction pathways leading to the formation of respective pyrans. Diverse possible mechanisms are encountered with the PTA@Ta2O5 catalyst based on the respective transformations. The solid-state structures of xanthenes and naphthopyrans are thoroughly investigated. Furthermore, some derivatives are studied in vitro to assess their antimicrobial activity, and the findings are compared with those of reference standard antibiotics. © 2025 Wiley-VCH GmbH.
Community detection using meta-heuristic approach: Bat algorithm variants
(2017) Sharma, J.; Annappa, B.
In the present world, it is hard to overlook - the omnipresence of 'network'. Be it the study of internet structure, mobile network, protein interactions or social networks, they all religiously emphasizes on network and graph studies. Social network analysis is an emerging field including community detection as its key task. A community in a network, depicts group of nodes in which density of links is high. To find the community structure modularity metric of social network has been used in different optimization approaches like greedy optimization, simulated annealing, extremal optimization, particle swarm optimization and genetic approach. In this paper we have not only introduced modularity metrics but also hamiltonian function (potts model) amalgamated with meta-heuristic optimization approaches of Bat algorithm and Novel Bat algorithm. By utilizing objective functions (modularity and hamiltonian) with modified discrete version of Bat and Novel Bat algorithm we have devised four new variants for community detection. The results obtained across four variants are compared with traditional approaches like Girvan and Newman, fast greedy modularity optimization, Reichardt and Bornholdt, Ronhovde and Nussinov, and spectral clustering. After analyzing the results, we have dwelled upon a promising outcome supporting the modified variants. � 2016 IEEE.
Community detection using meta-heuristic approach: Bat algorithm variants
(Institute of Electrical and Electronics Engineers Inc., 2017) Sharma, J.; Annappa, B.
In the present world, it is hard to overlook - the omnipresence of 'network'. Be it the study of internet structure, mobile network, protein interactions or social networks, they all religiously emphasizes on network and graph studies. Social network analysis is an emerging field including community detection as its key task. A community in a network, depicts group of nodes in which density of links is high. To find the community structure modularity metric of social network has been used in different optimization approaches like greedy optimization, simulated annealing, extremal optimization, particle swarm optimization and genetic approach. In this paper we have not only introduced modularity metrics but also hamiltonian function (potts model) amalgamated with meta-heuristic optimization approaches of Bat algorithm and Novel Bat algorithm. By utilizing objective functions (modularity and hamiltonian) with modified discrete version of Bat and Novel Bat algorithm we have devised four new variants for community detection. The results obtained across four variants are compared with traditional approaches like Girvan and Newman, fast greedy modularity optimization, Reichardt and Bornholdt, Ronhovde and Nussinov, and spectral clustering. After analyzing the results, we have dwelled upon a promising outcome supporting the modified variants. Â© 2016 IEEE.
Crosslinked polymer doped binary coatings for corrosion protection
(Elsevier B.V., 2018) Kaur, H.; Sharma, J.; Jindal, D.; Arya, R.K.; Ahuja, S.K.; Arya, S.
Solvent-based polymeric multilayer coatings prepared by ex-situ addition of crosslinked poly(styrene-co-divinyl benzene) in poly(styrene)-ethylbenzene solution were examined for corrosion protection of mild steel in a simulated water environment equivalent to sea water and acid rain. Electrochemical impedance spectroscopy (EIS) technique was used to determine the corrosion resistance behavior of the prepared polymeric coatings in 3.5 wt % of NaCl aqueous solution. EIS analysis suggested that the sample solution prepared by adding 1% crosslinked polymer in poly(styrene)-ethylbenzene solution, has better corrosion resistance as compared to the sample solutions prepared by adding 3% and 2% of crosslinked polymer in poly(styrene)-ethylbenzene solutions. Scanning electron microscopy (SEM) revealed that substrate coated with polymeric solution prepared by adding 1% of crosslinked polymer in poly(styrene)-ethyl benzene solution showed less corrosion as compared to the substrates coated with sample solutions prepared by adding 3% and 2% of crosslinked polymer in poly(styrene)-ethylbenzene solutions. © 2018 Elsevier B.V.