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Banerjee R.,Satyendra Nath Bose National Center for Basic science | Gangopadhyay S.,West Bengal State University
General Relativity and Gravitation | Year: 2011

We calculate the Komar energy E for a noncommutative inspired Schwarzschild black hole. A deformation from the conventional identity E = 2STH is found in the next to leading order computation in the noncommutative parameter θ (i.e. √θe-M2/θ)) which is also consistent with the fact that the area law now breaks down. This deformation yields a nonvanishing Komar energy at the extremal point TH = 0 of these black holes. We then work out the Smarr formula, clearly elaborating the differences from the standard result M = 2STH, where the mass (M) of the black hole is identified with the asymptotic limit of the Komar energy. Similar conclusions are also shown to hold for a deSitter-Schwarzschild geometry. © 2011 Springer Science+Business Media, LLC.


Pal S.,Satyendra Nath Bose National Center for Basic science
Computational Materials Science | Year: 2013

Using ab initio calculation, we investigate systematically the structural and electronic properties of Ni2Nb1+xSn1-x (x = 0, 0.25, 0.50). Here, projector augmented wave approach (PAW) implemented in the Vienna ab initio simulation package (VASP) within generalized gradient approximation (GGA) for the exchange-correlation functional has been used. In this article, it is reported that though Ni2NbSn and Ni 2Nb1.25Sn0.75 have no structural transformation, Ni2Nb1.5Sn0.5 can transform to tetragonal structure from cubic L21 phase. The cubic lattice parameter decreases with Nb doping at Sn sites in off-stoichiometric alloys. The alloys are in paramagnetic phase in all the structures. The hybridization between Ni and Nb 3d states triggers the tetragonal distortion. Due to Nb doping in cubic L21 phase, there is a significant change in total density of states (DOSs) at Fermi energy (EF) (N(EF)). N(E F) increases with increasing Nb doping. But, N(EF) decreases during structural transformation of Ni2Nb 1.5Sn0.5. The superconducting critical temperature (T C) also changes with Nb doping in cubic phase and tetragonal distortion because TC very much depends on N(EF).© 2013 Elsevier B.V. All rights reserved.


Grant
Agency: Cordis | Branch: FP7 | Program: CSA-CA | Phase: NMP-2008-2.6-3 | Award Amount: 872.26K | Year: 2009

In a globalized world energy is a decisive factor for the further development and economic and social well being of the nations and stability in the different world regions. Materials science and research has in the past significantly contributed to solving issues in sustainable energy technologies. To bring about advancement and improvements in energy technologies and to address sustainability, research in nano-materials is expected to contribute significantly to solutions in a highly competitive and increasingly globalize world. Such research will inevitably have to be coordinated at European level but also internationally. In Europe, materials researchers cooperate increasingly in EU funded projects and bilaterally with non-European countries. The EU has concluded S&T agreements and implementation arrangements with India. It foresees the coordination and the execution of joint projects. This proposal intends to address the strategic assessment including synergy analysis of nano-materials research needs in the EU and India. It will establish and communicate to DG RTD and DST the mutual interests and the topics for future coordinated calls to enable the decision & policy makers and the funding bodies to make better informed decisions and to better select the implementation mechanisms and instruments. Beside the assessment, the proposal also addresses the dissemination of the nano-materials research acquis in the field by organization of events. Finally, it will bring together researchers for future research collaboration, to exchange ideas for joint projects and to inform each other on their core competencies & expertise. The project aims at the generation and enhancement of knowledge in materials science and research especially nano-materials applied to sustainable energy technologies. It also aims to increase the deployment of these materials in the technologies in both regions.


Chakraborty A.,Satyendra Nath Bose National Center for Basic science | Manna S.S.,Satyendra Nath Bose National Center for Basic science | Manna S.S.,Max Planck Institute For Physik Komplexer Systeme
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

Using a model of wealth distribution where traders are characterized by quenched random saving propensities and trade among themselves by bipartite transactions, we mimic the enhanced rates of trading of the rich by introducing the preferential selection rule using a pair of continuously tunable parameters. The bipartite trading defines a growing trade network of traders linked by their mutual trade relationships. With the preferential selection rule this network appears to be highly heterogeneous characterized by the scale-free nodal degree and the link weight distributions and presents signatures of nontrivial strength-degree correlations. With detailed numerical simulations and using finite-size scaling analysis we present evidence that the associated critical exponents are continuous functions of the tuning parameters. However the wealth distribution has been observed to follow the well-known Pareto law robustly for all positive values of the tuning parameters. © 2010 The American Physical Society.


Mohanty J.S.,Indian Institute of Technology Madras | Xavier P.L.,Indian Institute of Technology Madras | Chaudhari K.,Indian Institute of Technology Madras | Bootharaju M.S.,Indian Institute of Technology Madras | And 3 more authors.
Nanoscale | Year: 2012

We report the synthesis of luminescent AuAg alloy quantum clusters (QCs) in bovine serum albumin (BSA), for the first time, with experimentally determined atomic composition. Mixing of the as-synthesized protein-protected Au and Ag clusters resulted in the formation of alloy AuAg clusters within the BSA. Mass spectrometric analysis of the product of a 1:1 molar ratio reaction mixture of Au QC@BSA and Ag QC@BSA suggested that the alloy clusters could be Au 38-xAg x@BSA. Further analyses by standard techniques revealed that the alloy cluster core of ∼1.2 nm diameter is composed of nearly zero valent Au and Ag atoms that exhibit distinctly different steady state and time resolved excited state luminescence profiles compared to the parent clusters. Tuning of the alloy composition was achieved by varying the molar ratio of the parent species in the reaction mixture and compositional changes were observed by mass spectrometry. In another approach, mixing of Au 3+ ions with the as-synthesized Ag QC@BSA also resulted in the formation of alloy clusters through galvanic exchange reactions. We believe that alloy clusters with the combined properties of the constituents in versatile protein templates would have potential applications in the future. The work presents interesting aspects of the reactivity of the protein-protected clusters. This journal is © 2012 The Royal Society of Chemistry.

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