Chakraborty N.,IG and BC Hospital |
Jana J.,Kalyani University |
Sarkar G.M.,Ranaghat College |
Lahiri S.C.,Central Forensic Science Laboratory
Journal of the Indian Chemical Society | Year: 2012
Methanogens, acetogens and sulfate reducing bacteria are known as obligate anaerobes and ubiquitous in nature. They are believed not to survive in presence of air or oxygen, oxygen for their metabolism or growth usually comes from oxygen containing inorganic salts. Methane emission from rice paddy soils or by methanogens or acetogens in a synthetic broth medium in presence of limited supply of oxygen suggest that methanogens, acetogens arc capable of sustaining in limited supply of oxygen by an environmental adaptation. Methanogenic activities of formate reducing mehanogens isolated from local habitats in Breznak AC21 medium under oxic, partially oxic and anoxic conditions also suggest that methanogens have the capability of metabolic response and oxygen tolerance in limited supply of oxygen. No convincing mechanism of exhibiting aero-tolerance by the anaerobes has been suggested. A physico-chemical mechanism for the phenomenon of aero-tolerance of anaerobes has been put forward. Methanogenesis or other anaerobic activities are usually carried out under reducing conditions and at pH near or above 7. Under the conditions of the experiment, O 2 is usually converted to OH- in limited supply of O 2. The oxidation of anaerobic ponds shows initial increase of pH on passing O 2 for purification of water in anaerobic ponds which corroborates the physico-chemical mechanism of aerotolerance of anaerobes like methanogens.
Mitra S.,Ranaghat College |
Mukherjee S.K.,Kalyani University
Indian Journal of Traditional Knowledge | Year: 2010
Ethnomedicinal usages of 62 plant species commonly used by 11 tribal communities of North Bengal plain for the treatment of gastro-intestinal problems are provided.
Ghosh T.,Ranaghat College |
Ghosh T.,Indian Association for The Cultivation of Science |
Sengupta S.,Ranaghat College |
Sengupta S.,Indian Association for The Cultivation of Science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011
Considering generalised action for dilaton coupled Maxwell-Einstein theory in four dimensions, Gao and Zhang obtained black holes solutions for asymptotically anti de Sitter (Ads) and de Sitter (ds) spacetimes. We study the Hawking radiation in Parikh-Wilczek's tunneling formalism as well as using Bogoliubov transformations. We compare the expression of the Hawking temperature obtained from these two different approaches. Stability and the extremality conditions for such black holes are discussed. The exact dependences of the Hawking temperature and flux on the dilaton coupling parameter are determined. It is shown that the Hawking flux increases with the dilaton coupling parameter. Finally we show that the expression for the Hawking flux obtained using Bogoliubov transformation matches exactly with flux calculated via chiral gauge and gravitational anomalies. This establishes a correspondence among all these different approaches of estimating Hawking radiation from these classes of black holes. © 2010 Elsevier B.V.
Hazra S.,Kalyani University |
Mondal B.,Kalyani University |
Rahaman H.,Ranaghat College |
Roy B.,Kalyani University
European Journal of Organic Chemistry | Year: 2014
A Cu and Pd bi-catalytic system is found to be very effective for the indole C2-H functionalization/C-N bond formation process.This is a unique reaction in which isoquinoline systems were synthesized from aldoximes rather than from ketoximes. During the reaction Cu(OTf)2 converts the aldoximes into the corresponding cyanides and indoloisoquinolines, but introduction of Pd(OAc)2 changes the outcome of the reaction significantly, by suppressing the formation of cyano products, thus giving exclusively indoloisoquinolines. A range of substituted indoloisoquinolines and aza-indoloisoquinolines are prepared in good to very good yields under air. A new approach to the synthesis of indoloisoquinoline derivatives is described. The activation of the indole C2-H bond is accomplished here by using a Pd(OAc)2 and Cu(OTf)2 bi-catalytic system. In this reaction aldoximes are converted into the corresponding isoquinolines in open atmosphere under mild reaction condition. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Uniyal R.,Gurukul Kangri Vishwavidyalaya |
Nandan H.,Gurukul Kangri Vishwavidyalaya |
Biswas A.,Ranaghat College |
Purohit K.D.,Hemwati Nandan Bahuguna Garhwal University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
We study the geodesic motion of massive and massless test particles in the background of a particular class of multiple charge black holes in gauged supergravity theories in D=4. We have analyzed the horizon structure along with the nature of the effective potentials for the case of four equal charges. In view of the corresponding effective potentials, we have discussed all the possible orbits in detail for different values of energy and angular momentum of the incoming test particles. The periods for one complete revolution of circular orbits and the advance of perihelion of the planetary orbit have also been investigated in greater detail for massive test particles. We have also discussed the time period of unstable circular motion and cone of avoidance of massless test particles in detail. All the corresponding results obtained for massive and massless test particles are then compared accordingly. © 2015 American Physical Society.
Ghosh T.,Ranaghat College |
SenGupta S.,Indian Association for The Cultivation of Science
Astrophysics and Space Science | Year: 2015
We establish AdS-CFT correspondence for n-dimensional AdS dilaton coupled black hole. Following two different approaches to establish the correspondence we calculate the energy from supergravity theory as well as boundary two point function from bulk geodesic. © 2015, Springer Science+Business Media Dordrecht.
Chakraborty N.,Kalyani University |
Chakraborty N.,VIRUS UNIT |
Chatterjee M.,Kalyani University |
Chatterjee M.,Sea Explorer Institute |
And 4 more authors.
Bioenergy Research | Year: 2010
The effect of divalent metal ions on biomethanation was studied using pre-reduced methanogenic AC21 medium in absence or in presence of leaf or root extracts of Eichornia grassipes (water hyacinth) in vitro. The metal ions like Cu2+, Fe2+, Ni2+, and Co2+ were found to be effective in increasing methane production in vitro at low concentrations, but toxic inhibitory effects were observed at relatively high concentrations. Zn2+ ion was inhibitory in character with exceptions. The bioavailability of metal ions in AC21 medium alone or with juices from leaf or root extracts of plant (water hyacinth in the present case) was limited due to complex formation of metal ions with different constituents in the medium, precipitation, etc. However, the results of the microscopic experiments (in vials) with metal ions for methane production by isolated methanogens in the methanogenic medium should not be compared with the conversion of biomass to methane in biodigesters. In such cases, not only a large number of methanogenic bacteria of different strains but also a consortium of bacteria of different specificities is usually involved. Though the biomass may contain sufficient concentrations of metal ions, it is advisable to add metal ions like Cu2+, Fe2+, Zn 2+, Co2+, etc. in the biomass, but the concentrations of the metal ions should be limited to 10-20 μM of the biomass to make methane generation successful. © 2010 Springer Science+Business Media, LLC.