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Govinda Rajulu M.B.,Vivekananda Institute of Tropical Mycology | Thirunavukkarasu N.,Ramakrishna Mission Vivekananda College | Babu A.G.,Thapar University | Aggarwal A.,Thapar University | And 2 more authors.
Mycology | Year: 2013

The distribution of Xylaria endophytes in the leaves of 22 tree species of a dry thorn forest and 27 tree species of a stunted montane evergreen forest of the Western Ghats in southern India was studied. In addition, these endophytes were screened for the production of some bioactive metabolites and extracellular enzymes. All the tree species in both the forest types harboured xylariaceous endophytes. Generally, xylariaceous endophytic infection of the leaves increased during the wet season. Molecular analysis showed that most of the xylariaceous endophytes isolated belonged to Xylaria or Nemania. All endophytes produced cellulase, and most of the isolates produced laccase and lipase enzymes suggesting continuing their life in plant litter as saprotrophs. The culture extracts were inhibitory to fungi, bacteria and algae indicating that they can compete with such organisms in the forest floor while surviving as saprotrophs. Fungi with such dual life strategies appear to be a potential source for biotechnological exploitation. © 2013 Copyright 2013 Mycological Society of China.


Chakraborty M.,Pohang University of Science and Technology | Min B.I.,Pohang University of Science and Technology | Chakrabarti A.,Ramakrishna Mission Vivekananda College | Das A.N.,Saha Institute of Nuclear Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We have investigated bipolaron formation in the Holstein-Hubbard and the Fröhlich-Hubbard model on a discrete one-dimensional lattice. Phonon enriched basis has been generated by exploiting the idea of the Lang-Firsov transformation, which results in better convergence in the strong coupling regime. The incorporation of the finite-range electron-phonon (e-ph) interaction reduces the bipolaron effective mass. We systematically increase the spatial extent of the e-ph interaction to study the effect of the long-range tail of the Fröhlich model. The electron-electron (e-e) interaction also plays a crucial role in lowering the effective mass for both the Holstein and the Fröhlich bipolarons. In the presence of the extended e-e interaction, the intersite S1 Holstein bipolaron becomes unstable, while the effective mass of the Fröhlich bipolaron becomes significantly reduced for both the spin singlet and triplet cases. © 2012 American Physical Society.


Parthasarathy K.,Siddha Central Research Institute | Praveen C.,CSIR - Central Electrochemical Research Institute | Jeyaveeran J.C.,Ramakrishna Mission Vivekananda College | Prince A.A.M.,Ramakrishna Mission Vivekananda College
Bioorganic and Medicinal Chemistry Letters | Year: 2016

Microwave assisted synthesis of spirooxindoles via tandem double condensation between isatins and 4-hydroxycoumarin under gold catalysis is reported. The reaction is practical to perform, since the products can be isolated by simple filtration without requiring tedious column chromatography. The scope of this chemistry is exemplified by preparing structurally diverse spirooxindoles (22 examples) in excellent yields. Antimicrobial evaluation of the synthesized compounds revealed that three compounds (3a, 3f and 3s) exhibited significant MIC values in comparison to the standard drugs. Molecular docking studies of these compounds with AmpC-β-lactamase receptor revealed that 3a exhibited minimum binding energy (−117.819 kcal/mol) indicating its strong affinity towards amino acid residues via strong hydrogen bond interaction. All compounds were also evaluated for their in vitro cytotoxicity against COLO320 cancer cells. Biological assay and molecular docking studies demonstrated that 3g is the most active compound in terms of its low IC50 value (50.0 μM) and least free energy of binding (−8.99 kcal/mol) towards CHK1 receptor, respectively. © 2016 Elsevier Ltd


Thirunavukkarasu N.,Ramakrishna Mission Vivekananda College | Suryanarayanan T.S.,Vivekananda Institute of Tropical Mycology VINSTROM | Girivasan K.P.,Government Arts College for Men Autonomous | Venkatachalam A.,Vivekananda Institute of Tropical Mycology VINSTROM | And 3 more authors.
Fungal Diversity | Year: 2012

Ten marine sponge species from Rameswaram, southern India were studied for their filamentous fungal symbionts. The results suggest that fungal symbionts of marine sponges are hyperdiverse. Genera such as Acremonium, Alternaria, Aspergillus, Cladosporium, Fusarium and Penicillium were frequently isolated; no true marine fungal species were present. Species of Aspergillus were dominant and co-dominant in all the sponges screened. The fungal isolates produced antialgal, antifungal, antioxidant, antibiotic, antiinsect metabolites. A few fungi produced acetylcholinesterase inhibitors. © Kevin D. Hyde 2011.


Aizawa N.,Osaka Prefecture University | Kimura Y.,Osaka Prefecture University | Segar J.,Ramakrishna Mission Vivekananda College
Journal of Physics A: Mathematical and Theoretical | Year: 2013

The ℓ-conformal Galilei algebra, denoted by gℓ(d), is a non-semisimple Lie algebra specified by a pair of parameters (d, ℓ). The algebra is regarded as a nonrelativistic analogue of the conformal algebra. We derive hierarchies of partial differential equations which have invariance of the group generated by gℓ(d) with a central extension as kinematical symmetry. This is done by developing a representation theory such as Verma modules, singular vectors of gℓ(d) and vector field representations for d = 1, 2. © 2013 IOP Publishing Ltd Printed in the UK & the USA.


Chandrashekar R.,Chennai Mathematical Institute | Segar J.,Ramakrishna Mission Vivekananda College
Physica A: Statistical Mechanics and its Applications | Year: 2013

A unified framework to describe the adiabatic class of ensembles in the generalized statistical mechanics based on Schwämmle-Tsallis two parameter (q,q′) entropy is proposed. The generalized form of the equipartition theorem, virial theorem and the adiabatic theorem are derived. Each member of the class of ensembles is illustrated using the classical nonrelativistic ideal gas and we observe that the heat functions could be written in terms of the Lambert's W-function in the large N limit. In the microcanonical ensemble we study the effect of gravitational field on classical nonrelativistic ideal gas and a system of hard rods in one dimension and compute their respective internal energy and specific heat. We found that the specific heat can take both positive and negative values depending on the range of the deformation parameters, unlike the case of one parameter Tsallis entropy. © 2013 Elsevier B.V. All rights reserved.


Muniraj S.,National Chung Hsing University | Muniraj S.,Ramakrishna Mission Vivekananda College | Yan C.-T.,Chung Shan Medical University | Shih H.-K.,National Chung Hsing University | And 2 more authors.
Analytica Chimica Acta | Year: 2012

A new simultaneous derivatization and extraction method for the preconcentration of ammonia using new one-step headspace dynamic in-syringe liquid-phase microextraction with in situ derivatization was developed for the trace determination of ammonium in aqueous samples by liquid chromatography with fluorescence detection (LC-FLD). The acceptor phase (as derivatization reagent) containing o-phthaldehyde and sodium sulfite was held within a syringe barrel and immersed in the headspace of sample container. The gaseous ammonia from the alkalized aqueous sample formed a stable isoindole derivative with the acceptor phase inside the syringe barrel through the reciprocated movements of plunger. After derivatization-cum-extraction, the acceptor phase was directly injected into LC-FLD for analysis. Parameters affecting the ammonia evolution and the extraction/derivatization efficiency such as sample matrix, pH, temperature, sampling time, and the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger, were studied thoroughly. Results indicated that the maximum extraction efficiency was obtained by using 100μL derivatization reagent in a 1-mL gastight syringe under 8 reciprocated movements of plunger per min to extract ammonia evolved from a 20mL alkalized aqueous solution at 70°C (preheated 4min) with 380rpm stirring for 8min. The detection was linear in the concentration range of 0.625-10μM with the correlation coefficient of 0.9967 and detection limit of 0.33μM (5.6ngmL-1) based on SN-1=3. The method was applied successfully to determine ammonium in real water samples without any prior cleanup of the samples, and has been proved to be a simple, sensitive, efficient and cost-effective procedure for trace ammonium determination in aqueous samples. © 2012 Elsevier B.V.


Aizawa N.,Osaka Prefecture University | Chandrashekar R.,National Chung Hsing University | Segar J.,Ramakrishna Mission Vivekananda College
Journal of Physics: Conference Series | Year: 2015

Conformal Galilei algebra is a class of non-semisimple Lie algebras. Each member of the class is labelled by two parameters d (positive integer) and ℓ (positive integer or positive half-integer). We investigate the lowest weight representations of the conformal Galilei algebra for d = 1 and any integer ℓ. We start with the Verma modules and then extract all the irreducible lowest weight modules. This is done by searching and explicitly constructing singular vectors. As an application of our construction of singular vectors, we obtain the partial differential equations which are symmetric by kinematical transformation generated by the conformal Galilei algebra. © Published under licence by IOP Publishing Ltd.


Aizawa N.,Osaka Prefecture University | Kimura Y.,Osaka Prefecture University | Segar J.,Ramakrishna Mission Vivekananda College
Journal of Physics: Conference Series | Year: 2014

The ℓ-conformai Galilei algebra, denoted by gℓ(d), is a particular non-semisimple Lie algebra specified by a positive integer d and a spin value ℓ. The algebra gℓ(d) admits central extensions. We study lowest weight representations, in particular Verma modules, of g ℓ(d) with the central extensions for d = 1,2. We give a classification of irreducible modules over d 1 algebras and a condition of the Verma modules over d 2 algebras being reducible. As an application of the representation theory, hierarchies of differential equations are derived. The Lie group generated by gℓ(d) with the central extension is a kinematical symmetry of the differential equations. © Published under licence by IOP Publishing Ltd.


PubMed | Ramakrishna Mission Vivekananda College and New York University
Type: Journal Article | Journal: Physical review letters | Year: 2016

The distribution of coherence in multipartite systems is examined. We use a new coherence measure with entropic nature and metric properties, based on the quantum Jensen-Shannon divergence. The metric property allows for the coherence to be decomposed into various contributions, which arise from local and intrinsic coherences. We find that there are trade-off relations between the various contributions of coherence, as a function of parameters of the quantum state. In bipartite systems the coherence resides on individual sites or is distributed among the sites, which contribute in a complementary way. In more complex systems, the characteristics of the coherence can display more subtle changes with respect to the parameters of the quantum state. In the case of the XXZ Heisenberg model, the coherence changes from a monogamous to a polygamous nature. This allows us to define the shareability of coherence, leading to monogamy relations for coherence.

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