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Rahara, India

Roychowdhury D.,University of Calcutta | Ghosh B.,RKMVC College | Chaubey B.,University of Calcutta | Jha S.,University of Calcutta
Nucleus (India) | Year: 2013

Transgenic plants of Tylophora indica obtained via somatic embryogenesis through genetic transformation by Agrobacterium rhizogenes have been maintained in vitro for over 6 years and the comparison of long term cultures and field grown normal and transformed plants on various morphological, biochemical and molecular characterisation described. Ri-transformed plants were found to be morphologically stable after 6 years in axenic culture as well as after transfer to the field. Genetic stability for rolA, rolB, rolC and rolD genes were obtained in Ri-transformed plants prior to and after transfer to field. The chromosome number, 2n = 22 was maintained in all the transgenic plants. The Ri-transformed plants retained and expressed all the four rol genes after transfer to the field and were able to synthesise and accumulate tylophorine. Thus, the Ri-transformed plants were found to be stable for more than 6 years in vitro and after 1year of field transfer. © 2013 Archana Sharma Foundation of Calcutta. Source


Ghosh S.,Bethune College | Ghosh B.,RKMVC College | Jha S.,University of Calcutta
Plant Tissue Culture and Biotechnology | Year: 2015

Elicitation strategies were studied for yield enhancement of colchicine, produced by root cultures of Gloriosa superba. Adventitious root cultures were established and grown in media containing 3 mg/l NAA and 1 mg/l BA. Root cultures showed variations in biomass as well as colchicine production in the presence of different exogenous carbohydrates and amino acid. Among the different sources of carbohydrates used ‐ fructose, sucrose and dextrose gave a substantially higher biomass yield than the control. Maximum biomass was obtained in the presence of fructose. Root cultures growing in mannitol supplemented medium resulted in maximum accumulation of colchicine (0.32%). Among the amino acids, serine and phenylalanine significantly enhanced colchicine accumulation in root cultures. 0.02 mM glutamine supplemented media showed maximum (ten‐fold) increase of root biomass. © 2015, Bangladesh Association for Plant Tissue. All rights reserved. Source


Chakraborty M.,Saha Institute of Nuclear Physics | Das A.N.,Saha Institute of Nuclear Physics | Chakrabarti A.,RKMVC College
Journal of Physics Condensed Matter | Year: 2011

We present the effect of next-nearest-neighbor hopping on Holstein polarons. The energy and wavefunction of the ground state and first excited state are obtained by using a conjugate-gradient technique on the variational Hilbert space of the electron-phonon (e-ph) system. We increase the size of the variational space systematically to obtain high accuracy. With the converged wavefunction at our disposal we obtain various physical quantities and correlation functions to get a holistic insight into the physics of e-ph interaction. Our study reveals that the effect of next-nearest-neighbor hopping is most prominent at the physically interesting crossover regime of the e-ph coupling and in the adiabatic regime. We have also performed analytical strong coupling second order perturbation with a Lang-Firsov (LF) phonon basis to account for some features in the strong coupling regime. © 2011 IOP Publishing Ltd. Source


Kundu R.,RKMVC College
Pramana - Journal of Physics | Year: 2014

In this work, we uphold and extend the formalism advocated by us more than a decade ago in order to extract information on various distribution functions describing nucleonic helicity structure and calculate a complete set of splitting functions relevant for their quantum chromodynamics (QCD) evolutions using light-front Hamiltonian perturbation theory in light front gauge A+ = 0. Twist-two structures of the helicity distributions are self-evident in our calculation. Sum rules associated with these helicity distributions are also verified in a frame-independent way. © Indian Academy of Sciences Source


Harindranath A.,Saha Institute of Nuclear Physics | Kundu R.,RKMVC College | Mukherjee A.,Indian Institute of Technology Bombay
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

In this work we show that (i) both the form factors Ai and Ci contribute to the matrix element of the energy-momentum tensor T+~~ in a transversely polarized state, (ii) there is no relative suppression factor between these two contributions and (iii) the contribution to the matrix element of the Pauli-Lubanski operator Wf- from that of Ti ++ contains only the form factor Bi and not the form factor Ai. These results support our criticism and the conclusions as stated in Ref. [13]. Comparing and contrasting the spin sum rules in two different approaches, one advocated by us and the one proposed by Jaffe and Manohar, we point out that the physical content of the sum rules is very transparent in our approach, whereas, in the second approach details of the dynamics remain hidden and the separation into orbital and intrinsic spin parts is not visible. © 2013 The Authors. Published by Elsevier B.V. Source

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