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Notes on the oviposition behaviour of three Elattoneura damselflies from India (Odonata: Platycnemididae)
(Odonatologica,, 2021) Neha Mujumdar ., Ameya Deshpande ., Prosenjit Dawn ., Pankaj Koparde .,
Oviposition behaviour of three Indian Elattoneura spp. is described and discussed. Endophytic oviposition in dry rigid substrates away from water by the endemic E. nigerrima and E. tetrica is recorded; this differs from the typical recorded use of submerged vegetation substrates in the genus. Contrasting behavioural observation of oviposition in E. campioni is also discussed.
Dragonflies and damselflies (Insecta: Odonata) of West Bengal, an annotated list of species
(Oriental Insects,, 2022) Prosenjit Dawn .,
An updated checklist of Odonata known so far from the state West Bengal is presented here consisting 239 species belonging to 114 genera and 17 families. Eight species viz. Megalestes irma, Lestes garoensis, Calicnemia nipalica, Chlorogomphus mortoni, Somatochlora daviesi, Cephalaeschna viridifrons, C. triadica, Lyriothemis mortoni, are recorded for the first time from the state; and last two species are recorded for the first time from India. This paper indicates a prominent rise in the number of species than the previous published checklist, as many isolated species distribution records were lying undocumented. This paper also reflects the data from citizen science platforms and social media groups. Reference for the original descriptions, type locality and information of specimen repository of the recorded species are provided. Some doubtful identification and distribution records are also discussed here.
Density functional theory-based modeling of the half-metallic g-C3N4/CoN4 heterojunction for photocatalytic water splitting reaction
(Physical Chemistry Chemical Physics, 2024) Dhilshada V.N.;Chandran A.;Sen S.;Chattopadhyaya M.
Using density functional theory (DFT), we have investigated the structural, optical, electronic and magnetic properties of a graphitic carbon nitride (g-C3N4) and CoN4 composite to explore the effect of the heterojunction on the photocatalytic performance of g-C3N4. The structure of g-C3N4 is modified while complexing with CoN4 and the corresponding stabilization is confirmed through adhesion energy calculation. The phonon spectra analysis furthermore guaranteed the lattice-dynamic stability of the CoN4 bulk and the CoN4 slab. Pristine g-C3N4 is a wide band gap semiconductor, which becomes half metallic upon CoN4 inclusion. The metallicity in the g-C3N4/CoN4 composite originates from the spin down channel, keeping the spin up channel in a semiconducting state. The charge density analysis and work function calculation suggest a substantial amount of charge transfer from g-C3N4 to the CoN4 unit in the g-C3N4/CoN4 heterojunction. The model heterojunction of the g-C3N4/CoN4 composite can enhance the utilization ratio of visible light for the g-C3N4 photocatalyst. In g-C3N4/CoN4, the valence band maximum (VBM) has a more positive potential compared to O2/H2O (+1.23 V) on the normal hydrogen electrode (NHE) scale. However, the conduction band minimum (CBM) displays a more negative potential compared to H+/H2 (0 V) on the NHE scale. The details of the band structure, density of states and band edge position determining calculations confirm that the g-C3N4/CoN4 composite forms a type 1 heterojunction, making it a suitable photocatalyst for water splitting reaction. The practical application of the g-C3N4/CoN4 heterostructure as a photocatalyst was substantiated in the presence of polar solvent (water) by calculating the band gap, charge transfer interaction and charge density difference. There is a significant decrease of charge transfer and thereby charge density difference in the g-C3N4/CoN4 heterojunction in the presence of water; however, it still holds potential for use as a photocatalyst for water splitting reaction. The state-of-the-art theoretical modeling of the g-C3N4/CoN4 heterojunction is the first theoretical study incorporating the CoN4 crystal.
Description of the Last Instar Larva of Platylestes platystylus (Rambur, 1842) from Kerala, India (Odonata: Lestidae)
(Zootaxa,, 2023) Chandran A.V.;Jose S.K.;Dawn P.
The description of the final instar larva and the subsequent exuvia of Platylestes platystylus (Rambur, 1842) is given based on a single male larva collected from Kerala and reared in the laboratory. A brief account of the habitat of the damselfly and an updated key to the larvae of genera of Family Lestidae Calvert, 1901 are also provided.
Comparative study of the photocatalytic activity of g-C3N4/MN4 (M = Mn, Fe, Co) for water splitting reaction: A theoretical study
(Journal of Computational Chemistry, 2024) Dhilshada. V.N.;Sen S.;Chattopadhyaya M.
In this study, nanocomposites of g-C3N4/MN4 (where M is Mn, Fe and Co) have been designed using advanced density functional theory (DFT) calculations. A comprehensive analysis was conducted on the geometry, electronic, optical properties, work function, charge transfer interaction and adhesion energy of the g-C3N4/MN4 heterostructures and concluded that g-C3N4/FeN4 and g-C3N4/CoN4 heterojunctions exhibit higher photocatalytic performance than individual units. The better photocatalytic activity can be attributed mainly by two facts; (i) the visible light absorption of both g-C3N4/FeN4 and g-C3N4/CoN4 interfaces are higher compared to its isolated analogs and (ii) a significant enhancement of band gap energy in g-C3N4/FeN4 and g-C3N4/CoN4 heterostructures limited the electron–hole recombination significantly. The potential of the g-C3N4/MN4 heterojunctions as a photocatalyst for the water splitting reaction was assessed by examining its band alignment for water splitting reaction. Importantly, while the electronic and magnetic properties of MN4 systems were studied, this is the first example of inclusion of MN4 on graphene-based material (g-C3N4) for studying the photocatalytic activity. The state of the art DFT calculations emphasis that g-C3N4/FeN4 and g-C3N4/CoN4 heterojunctions are half metallic photocatalysts, which is limited till date.