Bidhannagar College

About: Bidhannagar College is a based out in . It is known for research contribution in the topics: Schiff base & Ligand. The organization has 80 authors who have published 130 publications receiving 647 citations.

Observation of giant dielectric constant in an assembly of ultrafine Ag particles

Abstract: Although the Gor'kov-Eliashberg effect in isolated ultrafine metal particles is forbidden due to the depolarization field inside it, a giant dielectric response $(\ensuremath{\varepsilon}\ensuremath{\sim}{10}^{10})$ is observed in an assembly of ultrafine metal particles connected to each other forming an interrupted metal strand. The metal strand, which has a very low depolarization field, is obtained by the application of electric field to the assembly of isolated minute metal particles. The strong electrostatic force due to high electric field ${(10}^{6}\mathrm{V}/\mathrm{c}\mathrm{m})$ in the nano air gap between the particles causes the particles to deform in the direction of the electric field and finally attains the percolating configuration with the formation of a metal filament, the electronic wave functions of which are localized due to lattice defects at the interface between the particles.

Current?voltage characteristics of conducting polypyrrole nanotubes using atomic force microscopy

Abstract: Conducting polypyrrole nanotubes are synthesized by an oxidation polymerization technique using an Anodisc alumina membrane as a template. The morphology is varied from solid rod-like structures to hollow tubes by changing the concentration of the ammonium persulphate (used as the oxidant) solution. The current distribution over the selected area of the membrane and the current–voltage (I–V) characteristics of a single nanotube have been investigated by atomic force microscopy. From the current distribution, the lowest wall thickness has been estimated to be and from the I–V characteristics it is seen that the intrinsic conductivity of the tube changes with the wall thickness. The conductivity for tubes with a wall thickness of has been calculated as .

Effects of nutrient limitation, salinity increase, and associated stressors on mangrove forest cover, structure, and zonation across Indian Sundarbans

Abstract: Anthropogenic coastal activities and natural stressors aggravate degradation of small coastal patches of mangroves, which in turn destroy local resilience of mangrove forests in the Indian Sundarbans, the continuous mangrove habitat that spans between India and Bangladesh. We conducted an analytical survey across 19 shoreline mangrove fringes spanning the Sundarbans, including both healthy and disturbed forests, and evaluated ninety-five 60-cm composite sediment cores across a degradation and salinity gradient from ~ 4 to ~ 12 ppt. Increased salinity and anoxicity greatly inhibited nutrient cycling and release by microbial decomposers, subsequently resulting in nutrient-poor soil as a condition of degradation. Nutrient limitation, salinity rise, anoxicity increase, and sulfide build-up negatively controlled forest structure causing declines of forest coverage from ~ 98 to ~ 11%. In addition, the tide-dominated salinity gradient controlling species zonation was disrupted in disturbed forests with salinity-sensitive species gradually disappearing. An obvious change in species distribution is anticipated while salt-sensitive Heritiera fomes, Xylocarpus spp., and Phoenix paludosa failed to cope with increased salinity, evident by their absence from many forests. Excoecaria agallocha and Avicennia spp. acclimated well and expanded freely into degraded forests across the Sundarbans. Overall, our study strongly establishes salinity intrusion as primary mechanism for mangrove degradation.

A Tripartite Interaction among the Basidiomycete Rhodotorula mucilaginosa, N2-Fixing Endobacteria, and Rice Improves Plant Nitrogen Nutrition

Abstract: Nitrogen (N) limits crop yield, and improvement of N nutrition remains a key goal for crop research; one approach to improve N nutrition is identifying plant-interacting, N2-fixing microbes. Rhodotorula mucilaginosa JGTA-S1 is a basidiomycetous yeast endophyte of narrowleaf cattail (Typha angustifolia). JGTA-S1 could not convert nitrate or nitrite to ammonium but harbors diazotrophic (N2-fixing) endobacteria (Pseudomonas stutzeri) that allow JGTA-S1 to fix N2 and grow in a N-free environment; moreover, P. stutzeri dinitrogen reductase was transcribed in JGTA-S1 even under adequate N. Endobacteria-deficient JGTA-S1 had reduced fitness, which was restored by reintroducing P. stutzeri. JGTA-S1 colonizes rice (Oryza sativa), significantly improving its growth, N content, and relative N-use efficiency. Endofungal P. stutzeri plays a significant role in increasing the biomass and ammonium content of rice treated with JGTA-S1; also, JGTA-S1 has better N2-fixing ability than free-living P. stutzeri and provides fixed N to the plant. Genes involved in N metabolism, N transporters, and NODULE INCEPTION-like transcription factors were upregulated in rice roots within 24 h of JGTA-S1 treatment. In association with rice, JGTA-S1 has a filamentous phase and P. stutzeri only penetrated filamentous JGTA-S1. Together, these results demonstrate an interkingdom interaction that improves rice N nutrition.

Lewis base controlled supramolecular architectures via non-covalent interactions of dioxomolybdenum(VI) complexes with an ONS donor ligand: DFT calculations and biological study

Abstract: Synthesis and characterization of five new mononuclear dioxomolybdenum(VI) complexes involving the Schiff base ligand (H2L) derived from 2-hydroxyacetophenone and S-benzyldithiocarbazate are reported. The ligand reacted with MoO2(acac)2 and a monodentate Lewis base forming cis-dioxo Mo(VI) complexes of the type [MoO2LB] (where B = THF, 1-methylimidazole, 1-allylimidazole, γ-picoline and pyridine). In all the complexes the ligand is coordinated to molybdenum via tridentate ONS donors phenolic oxygen, imine nitrogen and thioenolate sulfur. The crystal structures of the ligand and the five complexes have been determined by single crystal X-ray crystallography. These complexes are neutral with the metal having distorted octahedral geometry. All the complexes give rise to fascinating supramolecular architectures via hydrogen bonding and π–π stacking interactions. DFT calculations on the ligand and complexes are also carried out. The Schiff base ligand and its dioxomolybdenum(VI) complexes were tested against five human pathogenic bacteria Bacillus cereus, Bacillus subtilis, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa and a fungi Candida albicans to assess their efficiency as antimicrobial agents. The MIC (minimum inhibitory concentration) for antimicrobial activity ranges from 1.0–10.0 μg per disc. They were also found to be effective antioxidants of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.