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Kolkata, India

Haldar S.K.,Lady Brabourne College | Chakrabarti B.,Kalyani University | Chakrabarti B.,University of Sao Paulo
International Journal of Modern Physics B

We calculate Shannon information entropy of trapped interacting bosons in both the position and momentum spaces, Sr and Sk, respectively. The total entropy maintains the functional form S = a + b ln N for repulsive bosons. At the noninteracting limit the lower bound of entropic uncertainty relation is also satisfied whereas the diverging behavior of S r and Sk at the critical point of collapse for attractive condensate accurately calculates the stability factor. Next we study the dynamics of Shannon information entropy with varying interparticle potential. We numerically solve the time-dependent Gross-Pitaevskii equation and study the influence of increasing nonlinearity in the dynamics of entropy uncertainty relation (EUR). We observe that for small nonlinearity the dynamics is regular. With increase in nonlinearity although Shannon entropy shows large variation in amplitude of the oscillation, the EUR is maintained throughout time for all cases and it confirms its generality. We also study the dynamics in a very tight trap when the condensate becomes highly correlated and strongly inhomogeneous. Time evolution of total entropy exhibits aperiodic and fluctuating nature in very tight trap. We also calculate Landsberg's order parameter for various interaction strengths which supports earlier observation that entropy and order are decoupled. © 2013 World Scientific Publishing Company. Source

The absorption and fluorescence spectra of Acridine Orange and Safranin O (both cationic dyes) have been studied in solutions of different classes of surfactants - cationic (CTAB), anionic (SDS) and non-ionic (Triton X-100). The spectral changes of the dyes were observed in varying amounts of Triton X-100, CTAB and SDS and indicated the formation of charge-transfer dye-surfactant complex between the dyes and Triton X-100 caused by incorporation of the dye molecules to micelles. It was observed that there were two types of interactions between the dyes and micelles: hydrophobic and electrostatic. While the hydrophobic interactions play a dominant role in binding of the dyes to neutral Triton X-100, the electrostatic interactions explain the binding of dyes to anionic SDS. The binding of dyes to cationic CTAB may be explained in terms of a dominant role played by hydrophobic interactions over electrostatic repulsions. The spectral studies (both absorption and fluorescence) of dyes have also been carried out in different polar and non-polar solvents, and the corresponding Stokes' shifts of fluorescence from the absorption have been calculated. The Stokes' shifts have been found to increase with increasing polarity of the solvents. An attempt has been made to ascertain the polarity of the microenvironment of the dyes in micellar media from the photophysical characteristics of the dyes in solvents of known polarity. © 2009. Source

Bhattacharyya S.,Deys Medical Stores Manufacturing Ltd | Datta S.,University of Calcutta | Mallick B.,Lady Brabourne College | Dhar P.,University of Calcutta | Ghosh S.,University of Calcutta
Journal of Agricultural and Food Chemistry

Three different cultivars of marigold flowers (Tagetes patula L.) (marigold orange, marigold yellow, and marigold red) were analyzed for the lutein ester contents, and the in vitro antioxidative activities of the flower extracts were compared. The total antioxidant capacity, reducing power, hydroxyl, DPPH, and ABTS•+ radical scavenging activities, iron chelation capacity, and inhibition of lipid peroxidation in a linoleic acid emulsion system were measured. Iron-mediated Fenton reaction was carried out to evaluate the protective effect of leutin against DNA damage. The marigold orange (MGO) variety contains the maximum amount of lutein. It also had the highest DPPH radical scavenging activity and ABTS radical scavenging activity, with an EC50 value of 0.344 mg/mL. It was also the most effective against lipid peroxidation and hydroxyl radical scavenging activities. The MGO extract has the maximum reducing power. Hepatic cell damage in iron-mediated Fenton reaction caused by free radicals was reduced by the marigold extracts. Marigold flowers of Indian variety can be effectively utilized to produce lutein ester, which can be used as a food supplement or as an accessible source of natural antioxidants. © 2010 American Chemical Society. Source

Mondal A.K.,Vidyasagar University | Parui S.M.,Lady Brabourne College
African Journal of Biotechnology

Comparative banding pattern of the seed protein of 17 taxa belonging to the three families Mimosaceae, Caesalpiniaceae and Fabaceae was studied with the aim of testing the proposed delimitation of the order Leguminales (Fabales) into the three families or subfamilies and to assess the phylogenetic relationships within the three families. Cluster and pairing affinity or similarity index analysis of the data from total protein grouped the 17 taxa into three discrete clusters based on their families. Considerable amount of homology was observed in the banding pattern between the different taxa. © 2011 Academic Journals. Source

Roy K.,Lady Brabourne College | Chakrabarti B.,Kalyani University | Kota V.K.B.,Physical Research Laboratory
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

It is a well-known fact that the statistical behaviors of level fluctuation and level correlation in the energy-level spectra are the most efficient tool to characterize quantum chaos in nonintegrable quantum systems. The system of interacting trapped bosons is a complex system where the low-lying energy levels are highly influenced by the level repulsion. In this case, interatomic interaction is a dominating fact with strong level correlation between distant levels. Here we numerically calculate the correlation function, number variance, and Dyson-Mehta least-square deviation for the low-lying levels for a few thousand interacting trapped bosons, and our data show good analogy with the Gaussian orthogonal ensemble (GOE) results with a signature of chaos. In the next part of our study, the energy spectrum of these low-lying levels is considered as a discrete signal and the fluctuation of the excitation energy is considered as discrete time series. Then we calculate numerically the height-height correlation function for different order of momentum. In our study logarithmic correlation structure is found instead of multiscaling structure, and we observe that spectral statistics are compatible with those of GOE. © 2013 American Physical Society. Source

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