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Augustin M.,St Xaviers College Autonomous
Materials Today: Proceedings | Year: 2015

Zinc ferrite (ZnFe2O4) and Manganese ferrite (MnFe2O4) nanoparticles were prepared by the chemical co-precipitation method and calcinated at 8000C for 5hrs. The results of XRD and SEM show that sample product was crystalline with mixed type spinel with cubic structure. The FT-IR spectrum shows most intense absorption bands 464 cm-1 and 550 cm-1 due to the strong transition metal stretching. Uv-vis studies reveal the band gap energy variation between different metal substitutions in the synthesis. Coercivity of ZnFe2O4 and MnFe2O4 nanoparticles was calculated using VSM studies is in the range of 14.456 G and 50.495 G respectively. © 2015 Elsevier Ltd. Source

Dey S.,St Xaviers College Autonomous
2012 2nd International Conference on Digital Information Processing and Communications, ICDIPC 2012 | Year: 2012

In this paper, the author propose a method, SD-AEI, for image encryption, which is an upgraded module for SD-EI combined image encryption technique and basically has three stages: 1) In first stage, each pixel of image is converted to its equivalent eight bit binary number and in that eight bit number, the number of bits, which are equal to the length of password are rotated and then reversed; 2) In second stage, extended hill cipher technique is applied by using involutory matrix, which is generated by same password used in second stage of encryption to make it more secure; 3) In third stage, the whole image file is randomized multiple number of times using Modified MSA Randomization encryption technique and the randomization is dependent on an unique number, which is generated from the password provided for encryption. This proposed technique, SD-AEI, is very effective in encrypting any type of images and the results were very satisfactory. SD-AEI method is also compared with various other image encryption techniques and it was found that SD-AEI cryptographic method takes optimal amount of time when compared to other encryption techniques, for encrypting and decrypting an image file. This method can be used to encrypt any type of image file, especially secret images, where steganography has been applied, so that the contents in the image file can be kept more secure. © 2012 IEEE. Source

Basu S.,University of Arkansas | Roychoudhury A.,St Xaviers College Autonomous
BioMed Research International | Year: 2014

The present study considered transcriptional profiles and protein expression analyses from shoot and/or root tissues under three abiotic stress conditions, namely, salinity, dehydration, and cold, as well as following exogenous abscisic acid treatment, at different time points of stress exposure in three indica rice varieties, IR-29 (salt sensitive), Pokkali, and Nonabokra (both salt tolerant). The candidate genes chosen for expression studies were HKT-1, SOS-3, NHX-1, SAPK5, SAPK7, NAC-1, Rab16A, OSBZ8, DREBP2, CRT/DREBP, WRKY24, and WRKY71, along with the candidate proteins OSBZ8, SAMDC, and GST. Gene expression profile revealed considerable differences between the salt-sensitive and salt-tolerant rice varieties, as the expression in the latter was higher even at the constitutive level, whereas it was inducible only by corresponding stress signals in IR-29. Whether in roots or shoots, the transcriptional responses to different stressors peaked following 24 h of stress/ABA exposure, and the transcript levels enhanced gradually with the period of exposure. The generality of stress responses at the transcriptional level was therefore time dependent. Heat map data also showed differential transcript abundance in the three varieties, correlating the observation with transcript profiling. In silico analysis of the upstream regions of all the genes represented the existence of conserved sequence motifs in single or multiple copies that are indispensable to abiotic stress response. Overall, the transcriptome and proteome analysis undertaken in the present study indicated that genes/proteins conferring tolerance, belonging to different functional classes, were overrepresented, thus providing novel insight into the functional basis of multiple stress tolerance in indica rice varieties. The present work will pave the way in future to select gene(s) for overexpression, so as to generate broad spectrum resistance to multiple stresses simultaneously. © 2014 Supratim Basu and Aryadeep Roychoudhury. Source

Guha S.,St Xaviers College Autonomous | Chakraborty S.,Jadavpur University
General Relativity and Gravitation | Year: 2010

In the "braneworld scenario" ordinary standard model matter and non-gravitational fields are confined by some trapping mechanism to the 4-dimensional universe constituting the D3-branes which are embedded in a (4 + n)-dimensional manifold referred to as the 'bulk' (n being the number of extra dimensions). The notion of particle confinement is necessary for theories with non-compact extra dimensions, otherwise, the particles would escape from our 4-dimensional world along unseen directions. In this paper, we have considered a five-dimensional warped product space-time having an exponential warping function which depends both on time as well as on the extra coordinates and a non-compact fifth dimension. Assuming that the lapse function may either be a constant or a function of both time and of the extra coordinates, we have studied the nature of the geodesics of test particles and photons and have analyzed the conditions of stability in this geometrical framework. We have also discussed the possible cosmology of the corresponding (3 + 1)-dimensional hypersurfaces. © 2010 Springer Science+Business Media, LLC. Source

Guha S.,St Xaviers College Autonomous | Banerji R.,Saha Institute of Nuclear Physics
International Journal of Theoretical Physics | Year: 2014

We have studied the dynamics of a cylindrical column of anisotropic, charged fluid which is experiencing dissipation in the form of heat flow, free-streaming radiation, and shearing viscosity, undergoing gravitational collapse. We calculate the Einstein-Maxwell field equations and, using the Darmois junction conditions, match the interior non-static cylindrically symmetric space-time with the exterior anisotropic, charged, cylindrically symmetric space-time. The behavior of the density, pressure and luminosity of the collapsing matter has been analyzed. From the dynamical equations, the effect of charge and dissipative quantities over the cylindrical collapse are studied. Finally, we have derived the solutions for the collapsing matter which is valid during the later stages of collapse and have discussed the significance from a physical standpoint. © 2014, Springer Science+Business Media New York. Source

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