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A Generalisation of Contraction Principle in Metric Spaces
Dutta PN,Choudhury BinayakS
Fixed Point Theory and Applications , 2008,
Abstract: Here we introduce a generalisation of the Banach contraction mapping principle. We show that the result extends two existing generalisations of the same principle. We support our result by an example.
Growth kinetics of NaCl crystals in a drying drop of gelatin: transition from faceted to dendritic growth
Moutushi Dutta Choudhury,Tapati Dutta,Sujata Tarafdar
Physics , 2015,
Abstract: We report a study on the kinetics of drying of a droplet of aqueous gelatin containing sodium chloride. The process of drying recorded on video, clearly shows different regimes of growth leading to a variety of crystalline patterns. Large faceted crystals of $\sim$mm size form in the early stages of evaporation, followed by highly branched multi-fractal patterns with micron sized features. We simulate the growth using a simple algorithm incorporating aggregation and evaporation, which reproduces the cross-over between the two growth regimes. As evaporation proceeds, voids form in the gel film. The time development of the fluid-void system can be characterized by an Euler number. A minimum in the Euler number marks the transition between the two regimes of growth.
Distribution of Antimony in a Tropical Estuary Dominated by Mangroves  [PDF]
Sanjay K Mandal, Natasha Majumdar, Chumki Choudhury, Raghab Ray, Manab K Dutta, Tapan K Jana
Journal of Environmental Protection (JEP) , 2011, DOI: 10.4236/jep.2011.26095
Abstract: Seasonal variation of antimony was studied in order to characterize its distribution in estuarine water, pore water, sediment, and digenetic behavior in the Sundarbans mangrove ecosystem. The mean concentration of dissolved inorganic Sb ranged between 230.8 and 303.1 ng L–1 over the period of study with a minimum during the post-monsoon closely associated with spring diatom bloom. Molecular diffusion flux of Sb was found greater than its value advected and deposited on sediment-water interface and there was significant remobilization of Sb in the Sundarbans mangrove ecosystem.
IN VITRO PROPAGATION OF DIPTERIS WALLICHII (R.BR.) T. MOORE: A HOPE FOR CONSERVATION OF AN ENDANGERED PTERIDOPHYTE
Singha, Kh. Bharati,Dutta Choudhury,Manabendra,Mazumder
International Research Journal of Pharmacy , 2013, DOI: 10.7897/2230-8407.04346
Abstract: The pteridophytes include the fern and fern allies which jointly create the necessary environment for human life on earth with other green plants. Dipteris wallichii (R.Br.) T. Moore is a rare and endemic pteridophyte of North East India. It is also facing severe threats due to its habitat destruction. Tribals destroy the plant in large numbers for preparing their wine drinking pipes. An in vitro protocol for micropropagation of D.wallichii Moore was carried out using standard Murashige and Skoog medium for spore germination and further cell proliferation. It was observed that supplementation of phytohormones mainly auxins (Indole-3-Acetic Acid) were favourable for sporophyte development from prothallus. Further growth and differentiation of the prothallus and sporophyte were recorded for various hormone concentrations and combinations and was observed to be best in 0.15 mg/L IAA + 0.20 mg/L KIN.
A Generalisation of Contraction Principle in Metric Spaces
P. N. Dutta,Binayak S. Choudhury
Fixed Point Theory and Applications , 2009, DOI: 10.1155/2008/406368
Abstract: Here we introduce a generalisation of the Banach contraction mapping principle. We show that the result extends two existing generalisations of the same principle. We support our result by an example.
Composite Electrolyte Membranes from Partially Fluorinated Polymer and Hyperbranched, Sulfonated Polysulfone
Surya Subianto,Namita Roy Choudhury,Naba Dutta
Nanomaterials , 2014, DOI: 10.3390/nano4010001
Abstract: Macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF) was done with various proportions of sulfonic acid terminated, hyperbranched polysulfone (HPSU) with a view to prepare ion conducting membranes. The PVDF-co-HFP was first chemically modified by dehydrofluorination and chlorosulfonation in order to make the membrane more hydrophilic as well as to introduce unsaturation, which would allow crosslinking of the PVDF-co-HFP matrix to improve the stability of the membrane. The modified samples were characterized for ion exchange capacity, morphology, and performance. The HPSU modified S-PVDF membrane shows good stability and ionic conductivity of 5.1 mS cm ? 1 at 80 °C and 100% RH for blends containing 20% HPSU, which is higher than the literature values for equivalent blend membranes using Nafion. SEM analysis of the blend membranes containing 15% or more HPSU shows the presence of spherical domains with a size range of 300–800 nm within the membranes, which are believed to be the HPSU-rich area.
Triviality Bound on Lightest Higgs Mass in NMSSM
S. R. Choudhury,Mamta,Sukanta Dutta
Physics , 1995, DOI: 10.1007/BF02847527
Abstract: We study the implication of triviality on Higgs sector in next to minimal supersymmetric model (NMSSM) using variational field theory. It is shown that mass of the lightest Higgs boson in NMSSM has an upper bound $\sim 10\, M_W$ which is of the same order as that in standard model.
Squeeze flow of potato starch gel: effect of loading history on visco-elastic properties
Moutushi Dutta Choudhury,Shantanu Das,Sujata Tarafdar
Physics , 2015,
Abstract: In this work gelatinized potato starch is shown to retain the memory of past loading history. It exhibits a visco-elastic response which does not depend solely on instantaneous conditions. A simple squeeze flow experiment is performed, where loading is done in two steps with a time lag $\tau \sim$ seconds between the steps. The effect on the strain, of varying $\tau$ is reproduced by a three element visco-elastic solid model. Non-linearity is introduced through a generalized calculus approach by incorporating a non-integer order time derivative in the viscosity equation. A strain hardening proportional to the time lag between the two loading steps is also incorporated. This model reproduces the three salient features observed in the experiment, namely - the memory effect, slight initial oscillations in the strain as well as the long-time solid-like response. Dynamic visco-elasticity of the sample is also reported.
A supersymmetric resolution of the anomaly in charmless nonleptonic $B$-decays
Debajyoti Choudhury,B. Dutta,Anirban Kundu
Physics , 1998, DOI: 10.1016/S0370-2693(99)00437-2
Abstract: We examine the large branching ratio for the process $B\to \eta^{\prime} K$ from the standpoint of R parity violating supersymmetry. We have given all possible $R_p$ violating contributions to $B\to \eta^{\prime} K$ amplitudes. We find that only two pairs of $\lambda^{\prime}$-type $R_p$ violating couplings can solve this problem after satisfying all other experimental bounds. We also analyze those modes where these couplings can appear, {\em e.g.}, $B^\pm \to \pi^{\pm}K^0$, $B^{\pm,0} \to K^{*\pm,0} \eta^{(\prime)}$, $B^{\pm} \to\phi K^{\pm}$ etc., and predict their branching ratios. Further, one of these two pairs of couplings is found to lower the branching ratio of $B^{\pm}\to\phi K^\pm$, thereby allowing larger $\xi\equiv{1\over N_c}$. This allows us to fit $B^{\pm}\to \omega K^{\pm}$ and $B^{\pm}\to \omega \pi^{\pm}$, which could not be done in the SM framework.
Pattern Formation in a Drying Drop of Starch Gel with Sodium Chloride
Moutushi Dutta Choudhury,Sayanee Jana,Sruti Dutta,Sujata Tarafdar
Physics , 2012,
Abstract: A drop of aqueous potato starch gel with a certain mole fraction of NaCl, when dried on a glass slide, exhibits strong segregation and intricate pattern formation phenomena. The salt forms radial dendritic crystalline aggregates near the centre, with the starch separating out in the form of a transparent band at the periphery. Photographs and micrographs show a series of concentric rings with different texture.
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