Gupta K.,Bhabha Atomic Research Center |
Gupta K.,Ramananda College |
Ghanty T.K.,Bhabha Atomic Research Center |
Ghosh S.K.,Bhabha Atomic Research Center
Physical Chemistry Chemical Physics | Year: 2010
An ab initio investigation of the polarizabilities of the first two excited states of methanol clusters [(CH3OH)n, n = 1-12] has been carried out employing time dependent density functional theory with B3LYP exchange correlation functional using 6-311++G(d,p) and Sadlej basis sets. Good linear correlations have been demonstrated for the first and second excited state polarizabilities as a function of the aggregation number (n) of the methanol clusters. On the contrary, for water clusters the variations of excited state polarizabilities with cluster size are found to be non-monotonic. The variations of the excitation energies and oscillator strengths with n for the first three excited states of methanol clusters and water clusters are also reported. © 2010 the Owner Societies.
Bhattacharjee B.,Ramananda College |
Lu C.-H.,National Taiwan University
Journal of Nanotechnology | Year: 2011
Bright ZnS:Mn 2+ nanoparticles have been synthesized employing microwave irradiation technique and using zinc 2-ethylhexanoate as a novel zinc precursor. A series of samples is obtained by changing the microwave power (from 150W to 500W) to study its effect on the physical properties of the ZnS:Mn2+ nanoparticles. The particle size increases with increasing microwave power for the samples synthesized in the microwave range of 150 W to 300 W. The decrease in particle size for higher microwave power (400W and 500W) can be described as an onset of the secondary nucleation due to the excess energy associated with the higher microwave power. The sample synthesized with microwave power of 300W shows highest luminescence intensity suggesting increase in Mn 2+ luminescence center for the sample synthesized at 300W, as supported by the quantity analysis results. © 2011 Baibaswata Bhattacharjee and Chung-Hsin Lu.
Khan M.A.,Ramananda College |
Sahoo B.,University of Calcutta
Optik | Year: 2016
In this paper, we study temporospatial synchronization behaviour of discrete Logistic maps under complex network. Our complex network is dynamic whose coupling connections are changed stochastically in time. Here we investigate the temporospatial synchronization of coupled discrete Logistic maps whose coupling connections are rewired randomly. Our aim is to determine (a) the effects of variation of randomness, (b) the effects of variation of coupling strength ε and (c) the effects of variation of parameter r. Linear stability analysis of the synchronized steady state solution is done analytically. We have calculated analytically the critical coupling coefficient for the transition to temporospatial regularity of the lattice. Our analytical results match very well with the numerical simulation results and lastly variations of the basin size with respect to rewiring probability with different coupling strengths are plotted. The simulation results will not change significantly with the variation of lattice size. © 2015 Elsevier GmbH. All rights reserved.
Sahu P.,Jadavpur University |
Shee S.K.,Midnapore College |
Hamada A.S.,University of Oulu |
Hamada A.S.,Suez Canal University |
And 6 more authors.
Acta Materialia | Year: 2012
The deformation behavior of a Cr-Mn austenitic steel during interrupted low strain rate uniaxial tensile testing at -80°C has been studied using X-ray diffraction (XRD), electron backscatter diffraction and transmission electron microscopy. Continuous γ → → α′ martensite transformation was observed until failure. High dislocation densities were estimated in the austenite phase (∼10 15 m -2), and for the α′-martensite they were even an order of magnitude higher. Dislocation character analysis indicated that increasing deformation gradually changed the dislocation character in the austenite phase to edge type, whereas the dislocations in α′-martensite were predominantly screw type. XRD analyses also revealed significant densities of stacking faults and twins in austenite, which were also seen by transmission electron microscopy. At low strains, the deformation mode in austenite was found to be dislocation glide, with an increasing contribution from twinning, as evidenced by an increasing incidence of ∑3 boundaries at high strains. The deformation mode in α′-martensite was dominated by dislocation slip. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Mukherjee R.,Jadavpur University |
Sahu T.,Ramananda College |
Sen S.,Indian National Metallurgical Laboratory |
Sahu P.,Jadavpur University
Materials Chemistry and Physics | Year: 2011
X-ray diffraction studies employing the Rietveld analysis is reported on the influence of increasing Co substitution on the structural and microstructural evolution in AB2O4 type spinel ferrites: Ni1-xCoxFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0). The specimens were synthesized by the organic precursor method. Structure refinement reveals that the pure NiFe2O4 is not an exact inverse spinel and about 11% of Ni2+ ions occupy the tetrahedral (A) sites. Increasing Co concentrations had the effect of increasing the ratio of Fe3+B/Fe3+A and gradual expansion of the ferrite unit cell. The microstructure refinement estimates that the particle size values are in the order of ∼nm, ranging from 31 to 61 nm, which gradually increase with increasing Co doping accompanied by almost negligible lattice micro strains (∼10-4). The corresponding particle size distribution for each specimen was obtained from the X-ray diffraction data from the basic assumption that the spherical nanoparticles follow the log-normal distribution. The size distribution for the pure NiFe 2O4 was also estimated from transmission electron microscope and agreed well with that obtained by the diffraction data analysis. © 2011 Elsevier B.V. All rights reserved.
Ghosh B.,Ramananda College |
Pradhan S.K.,University of Burdwan
Materials Chemistry and Physics | Year: 2010
Nanocrystalline TiC is produced by mechanical milling the stoichiometric mixture of α-Ti and graphite powders at room temperature under argon atmosphere within 35 min of milling through a self-propagating combustion reaction. Microstructure characterization of the unmilled and ball-milled samples was done by both X-ray diffraction and electron microscopy. It reveals the fact that initially graphite layers were oriented along 〈0 0 2〉 and in the course of milling, thin graphite layers were distributed evenly among the grain boundaries of α-Ti particles. Both α-Ti and TiC lattices contain stacking faults of different kinds. The grain size distribution obtained from the Rietveld's method and electron microscopy studies ensure that nanocrystalline TiC particles with almost uniform size (∼13 nm) can be prepared by mechanical alloying technique. The result obtained from X-ray analysis corroborates well with the microstructure characterization of nanocrystalline TiC by electron microscopy. © 2009 Elsevier B.V. All rights reserved.
Gupta K.,Ramananda College
Research Journal of Chemistry and Environment | Year: 2012
Eight structurally similar dihydroxy and trihydroxyphenolic acids (protocatechuic acid, 3,4-dyhydroxyphenyl acetic acid, hydrocaffeic acid, caffeic acid, gallic acid, 3,4, 5-trihydroxyphenyl acetic acid, 3-(3, 4, 5-trihydroxyphenyl)propanoic acid and 3-(3, 4, 5-trihydroxyphenyl)propenoic acid were investigated for important radical scavenging descriptors like O-H bond dissociation enthalpies (BDE), ionization potentials and, HOMO energies, spin density at radical forming point in the radical forming point by density functional method. It is observed that the type of spacer between the carboxylic acid and the aromatic ring influences scavenging descriptors.
Chatterjee N.,Ramananda College |
Bhattacharjee B.,Ramananda College
Advanced Science Letters | Year: 2016
The alterations in water quality due to addition of ZnS nanoparticles lead to change in physiological behaviour in Mystus vittatus (Bloch). The oogenesis process in the fish is found to be affected when the fish is exposed to ZnS nanoparticles (NPs) over a certain concentration (250 μg/L). Most of the fishes treated with ZnS NPs at a relatively higher concentration (500 μg/L) fail to complete the maturation process required for spawning. The vitellogenesis process is found to be delayed under low level of ZnS NPs concentration (250 μg/L) owing to lesser availability of dissolved oxygen required for the normal metabolism. The most striking observation has been witnessed at a relatively higher ZnS NPs concentration (500μg/L) level, when the fish prefers to avoid the spawning by restricting the process of vitellogenesis. © 2016 American Scientific Publishers All rights reserved.
Bhattacharjee B.,Ramananda College |
Chatterjee N.,Ramananda College
Advanced Science Letters | Year: 2016
Mystus vittatus shows abnormal pattern of testicular cell development with increasing number of structurally deformed sperms and decreased sperm count when exposed to ZnS nanoparticles (NPs) of concentrations 250 μg/L and higher. This hinders the spawning process of this nutritious fish, which is commercially important in south-east Asian fish market. The abnormality in spermatogenesis process in Mystus vittatus can be associated with the reducing level of dissolved oxygen content in water due to enhanced photo oxidation property of ZnS nanoparticles in nanoparticle form, present into the water. © 2016 American Scientific Publishers All rights reserved.
Sarkar S.,Ramananda College |
Chaudhuri S.,Kalyani University
Canadian Journal of Microbiology | Year: 2015
Ralstonia solanacearum is known to be the most prominent causal agent of bacterial wilt worldwide. It has a wide host range comprising solanaceous and nonsolanaceous plants. Typical symptoms of the disease are leaf wilt, browning of vascular tissues, and collapsing of the plant. With the objective of studying the diversity of pathogens causing bacterial wilt in West Bengal, we collected samples of diseased symptomatic crops and adjacent symptomatic and asymptomatic weeds from widespread locations in West Bengal. By means of a routine molecular identification test specific to “R. solanacearum species complex”, the majority of these strains (68 out of 71) were found to not be R. solanacearum. Presumptive identification of these isolates with conventional biochemicals, extensive testing of pathogenicity of a subset involving greenhouse trials fulfilling Koch’s postulate test, and scanning electron microscopic analysis for the presence of pathogen in diseased plants were done. 16S rDNA sequencing of a subset of these strains (GenBank accession Nos. JX880249–JX880251) and analysis of sequences with the nBLAST programme showed a high similarity (97%–99%) to sequences of the Enterobacteriaceae group available in GenBank. Molecular phylogeny further established the taxonomic position of the strains. The 3 bacterial strain cultures have been submitted to MTCC, Institute of Microbial Technology, Chandigarh, India, and were identified as Klebsiella oxytoca, Enterobacter cowanii, and Klebsiella oxytoca, respectively. Although Enterobacter sp. Has previously been reported to cause wilt in many plants, susceptibility of most of the dedicated hosts of R. solanacearum to wilt caused by Enterobacter and other bacteria from Enterobacteriaceae is being reported for the first time in this work.