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Search Results: 1 - 10 of 1857 matches for " Surajit Saha "
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Polarizabilities of Impurity Doped Quantum Dots under Pulsed Field: Role of Additive White Noise  [PDF]
Surajit Saha, Manas Ghosh
Open Journal of Microphysics (OJM) , 2015, DOI: 10.4236/ojm.2015.51001
Abstract: We make a rigorous exploration of the profiles of a few diagonal and off-diagonal components of linear (αxx, αyy, αxy andαyx), first nonlinear (βxxx, βyyy, βxyy andβyxx), and second nonlinear (γxxxx, γyyyy, γxxyyandγyyxx) polarizabilities of quantum dots under the influence of external pulsed field. Simultaneous presence of additive white noise has also been considered. The quantum dot contains dopant described by a Gaussian potential. The numbers of pulse and the dopant location have been found to fabricate the said profiles jointly. The β components display greater complexity in their profiles in comparison with the α and γ counterparts. The presence of noise prominently enhances the influence of dopant coordinate on the polarizability profiles, particularly for α and γ components. However, for β components, the said influence becomes quite evident both in the presence and absence of additive noise. The study reveals some means of achieving stable, enhanced, and often maximized output of noise-driven linear and nonlinear polarizabilities.
ISSR Fingerprinting to Ascertain the Genetic Relationship of Curcuma sp. of Tripura  [PDF]
Kishan Saha, Rabindra Kumar Sinha, Surajit Basak, Sangram Sinha
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.72025
Abstract: Molecular fingerprints of four different species of Curcuma, viz., C. amada, C. caesia, C. longa and C. zedoaria, found in Tripura were developed using Inter Simple Sequence Repeats. Twenty ISSR primers generated 116 loci amplified in the range of 200 - 5000 bp with an average of 5.8 alleles and 1.6 effective alleles per locus. The percentage of polymorphic band was found to be 86.29 with an average of 5.15 per primer. Based on UPGMA algorithm these four species are placed in two different clusters that validate the classification based on external and internal morphological characters. The polymorphic ISSR markers generated from this study will be useful for understanding the genetic relationship of different species of the genus Curcuma.
Crystallization and order-disorder transition of colloidal particles in a drying suspension: a phase field crystal approach
Nirmalendu Ganai,Arnab Saha,Surajit Sengupta
Physics , 2012,
Abstract: Using a phase field crystal model we study the structure and dynamics of a drop of colloidal suspension during evaporation of the solvent. We model an experimental system where contact line pinning of the drop on the substrate is non-existent. Under such carefully controlled conditions, evaporation of the drop produces an ordered or disordered arrangement of the colloidal residue depending on the initial average density of solute and the drying rate. We obtain a non-equilibrium phase boundary showing amorphous and crystalline phases of single component and binary mixtures of colloidal particles in the density- drying rate plane. While single component colloids order in the two dimensional triangular lattice, a symmetric binary mixture of mutually repulsive particles orders in a three sub-lattice order where two of the sub-lattices of the triangular lattice are occupied by the two species of particles with the third sub-lattice vacant.
Silver Inhibits the Biofilm Formation of Pseudomonas aeruginosa  [PDF]
Bipin Kumar Sharma, Animesh Saha, Lovely Rahaman, Surajit Bhattacharjee, Prosun Tribedi
Advances in Microbiology (AiM) , 2015, DOI: 10.4236/aim.2015.510070
Abstract: Biofilm is the assemblage of microbial cells that are irreversibly associated with biotic and abiotic surfaces and is usually enclosed in the self secreted extracellular polymeric substances (EPS). The presence of EPS in biofilm makes the microbial population resistance against antibiotics and other drugs. Biofilms are considered as a serious challenge to pharmaceutical industries because most of the microbial diseases are now associated with biofilm. In this context, we have addressed the biofilm potentialities of Pseudomonas aeruginosa, which has been found to be associated with several deadly diseases including septicemia, urinary tract infections, and gastrointestinal infections, and wherein biofilm plays a crucial role in pathogenesis. Since silver had been used globally for a long time for treating a wide range of illnesses from burn wounds, typhoid, and anthrax to bacterial conjunctivitis in newborns, but its antibiofilm activity is still unknown. Thus, in this current study, we have tried to examine the antibiofilm potentiality of silver against the biofilm of Pseudomonas aeruginosa. Our result showed that silver exhibited considerable antimicrobial property against Pseudomonas aeruginosa where the minimum inhibitory concentration (MIC) was found at 25 μg/ml. Biofilm inhibition by silver against Pseudomonas aeruginosa was then evaluated by crystal violet (CV) staining, estimation of total biofilm protein and microscopy based microbial adherence test using the sub MIC doses of silver. The results showed that all the tested sub MIC doses of silver exhibited considerable antibiofilm activity against P. aeruginosa, wherein the maximum biofilm attenuation was showed by a silver concentration of 20 μg/ml. We also observed that all these sub MIC doses
Correlation Between Clinical And Histopathological Criteria For The Classification Of Leprosy
Mitra Kalyani,Biswas Surajit,Saha Bibhuti,Dasgupta Anjali
Indian Journal of Dermatology , 2001,
Abstract: Clinicians and histopathologists sometimes disagree on the classification of a case of leprosy. A detailed histopathological study of 92 fresh uncomplicated cases representing the whole spectrum of leprosy was done for the last one year. There was complete agreement between clinical and histopathological diagnosis in 53 cases (57.61)% and disparity in 39 cases (42.39%). Among the latter, shift towards the lepromatous pole of the spectrum was found in 13 cases (14.13%) and shift towards tuberculoid pole in 26 cases (28.26%). The latter group included 16 cases (17.39%) where histopathological diagnosis was indeterminate leprosy because of the presence of early histopathological changes. It is concluded that in case of discrepancy, the more advanced finding (i.e. towards the lepromatous pole) should be given greater weightage and the case is to be classified and treated accordingly.
Electrical transport in deformed nanostrips: electrical signature of reversible mechanical failure
Soumendu Datta,Debasish Chaudhuri,Tanusri Saha-Dasgupta,Surajit Sengupta
Physics , 2005, DOI: 10.1209/epl/i2005-10448-8
Abstract: We calculate the electrical conductivity of a thin crystalline strip of atoms confined within a quasi one dimensional channel of fixed width. The conductivity shows anomalous behavior as the strip is deformed under tensile loading. Beyond a critical strain, the solid fails by the nucleation of alternating bands of solid and {\em smectic} like phases accompanied by a jump in the conductivity. Since the failure of the strip in this system is known to be reversible, the onductivity anomaly may have practical use as a sensitive strain transducer.
Berberine Chloride Mediates Its Anti-Leishmanial Activity via Differential Regulation of the Mitogen Activated Protein Kinase Pathway in Macrophages
Piu Saha,Surajit Bhattacharjee,Avijit Sarkar,Alak Manna,Subrata Majumder,Mitali Chatterjee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018467
Abstract: A complex interplay between Leishmania and macrophages influences parasite survival and necessitates disruption of signaling molecules, eventually resulting in impairment of macrophage function. In this study, we demonstrate the immunomodulatory activity of Berberine chloride in Leishmania infected macrophages.
Temperature-Dependent Infrared Reflectivity Studies of Multiferroic TbMnO_{3}: Evidence for Spin-Phonon Coupling
Pradeep Kumar,Surajit Saha,C. R. Serrao,A. K. Sood,C. N. R. Rao
Physics , 2009, DOI: 10.1007/s12043-010-0027-6
Abstract: We have measured near normal incidence far infrared (FIR) reflectivity spectra of a single crystal of TbMnO3 from 10K to 300K in the spectral range of 50 cm$^{-1}$ to 700 cm$^{-1}$. Fifteen transverse optic (TO) and longitudinal optic (LO) modes are identified in the imaginary part of the dielectric function $\epsilon_2$($\omega$) and energy loss function Im(-1/$\epsilon$($\omega$)), respectively. Some of the observed phonon modes show anomalous softening below the magnetic transition temperature T$_N$ (~ 46K). We attribute this anomalous softening to the spin-phonon coupling caused by phonon modulation of the super-exchange integral between the Mn$^{3+}$ spins. The effective charge of oxygen (Z$_O$) calculated using the measured LO-TO splitting increases below T$_N$.
Manifestation of geometric frustration on magnetic and thermodynamic properties of pyrochlores $Sm_2X_2O_7$ (X=Ti, Zr)
Surjeet Singh,Surajit Saha,S. K. Dhar,R. Suryanarayanan,A. K. Sood,A. Revcolevschi
Physics , 2007, DOI: 10.1103/PhysRevB.77.054408
Abstract: We present here magnetization, specific heat and Raman studies on single-crystalline specimens of the first pyrochlore member $Sm_2Ti_2O_7$ of the rare-earth titanate series. Its analogous compound $Sm_2Zr_2O_7$ in the rare-earth zirconate series is also investigated in the polycrystalline form. The Sm spins in $Sm_2Ti_2O_7$ remain unordered down to at least T = 0.5 K. The absence of magnetic ordering is attributed to very small values of exchange ($\theta_{cw} ~ -0.26 K$) and dipolar interaction ($\mu_{eff} ~ 0.15 \mu_B$) between the $Sm^{3+}$ spins in this pyrochlore. In contrast, the pyrochlore $Sm_2Zr_2O_7$ is characterized by a relatively large value of Sm-Sm spin exchange ($\theta_{cw} ~ - 10 K$); however, long-range ordering of the $Sm^{3+}$ spins is not established at least down to T = 0.67 K, due to frustration of the $Sm^{3+}$ spins on the pyrochlore lattice. The ground state of $Sm^{3+}$ ions in both pyrochlores is a well-isolated Kramer's doublet. The higher-lying crystal field excitations are observed in the low-frequency region of the Raman spectra of the two compounds recorded at T = 10 K. At higher temperatures, the magnetic susceptibility of $Sm_2Ti_2O_7$ shows a broad maximum at T = 140 K while that of $Sm_2Zr_2O_7$ changes monotonically. Whereas $Sm_2Ti_2O_7$ is a promising candidate for investigating spin-fluctuations on a frustrated lattice as indicated by our data, the properties of $Sm_2Zr_2O_7$ seem to conform to a conventional scenario where geometrical frustration of the spin exclude their long-range ordering.
Re-entrant ordering of solute in a colloidal suspension during solvent evaporation
Sumanta Mukherjee,Arnab Saha,Pralay K. Santra,Surajit Sengupta,D. D. Sarma
Physics , 2011,
Abstract: We study the phenomenon of self-assembly of silica micro-spheres on a glass plate during evaporation of the solvent from a colloidal suspension. Our experiments unveil an interesting competition between ordering and compaction in a strongly driven, out of equilibrium system arising from a slowing down of dynamics due to an impending glass transition. A suitable choice of experimental conditions minimizing the influence of many other competing phenomena that usually complicate probing of this underlying physics is crucial for our study. A re-entrant behavior in the order-disorder phase diagram as a function of particle density and drying time is established and the results are explained with the help of simulations and phenomenological theory.
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