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Search Results: 1 - 10 of 3601 matches for " Manas Ghosh "
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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.
Studies on Synthesis and Characterization of Magnesia Based Refractory Aggregates Developed from Indian Magnesite  [PDF]
Manas Kamal Haldar, Chandrima Ghosh, Arup Ghosh
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.210001

The present work intends to study the properties of magnesia based refractory aggregates developed from Indian magnesite by changing lime/silica ratio. The material has been sintered in the temperature range of 1550C - 1700C. The sintered samples are characterized in terms of bulk density, apparent porosity, true density, percentage densification, mechanical, thermo-mechanical properties like cold modulus of rupture, hot modulus of rupture and thermal shock resistance and structural properties by XRD. The developed microstructures at different temperatures are studied through FESEM study and compositional analysis of the developed phases is done by EDX study.

Influence of Oscillatory Impurity Potential and Concurrent Gasping of Impurity Spread on Excitation Profile of Doped Quantum Dots
Suvajit Pal,Manas Ghosh
Journal of Materials , 2013, DOI: 10.1155/2013/795450
Abstract: Excitation in quantum dots is an important phenomenon. Realizing the importance we investigate the excitation behavior of a repulsive impurity-doped quantum dot induced by simultaneous oscillations of impurity potential and spatial stretch of impurity domain. The impurity potential has been assumed to have a Gaussian nature. The ratio of two oscillations ( ) has been exploited to understand the nature of excitation rate. Indeed it has been found that the said ratio could fabricate the excitation in a remarkable way. The present study also indicates attainment of stabilization in the excitation rate as soon as η surpasses a threshold value regardless of the dopant location. However, within the stabilization zone we also observe maximization in the excitation rate at some typical location of dopant incorporation. The critical analysis of pertinent impurity parameters provides important perception about the physics behind the excitation process. 1. Introduction Nowadays we frequently encounter a plethora of theoretical and experimental researches on impurity states in low-dimensional heterostructures [1]. The advent of so-called low-dimensional structures such as quantum dots (QD) has considerably accelerated the technology-driven demand of miniaturization of semiconductor devices. The quantized properties of quantum dots doped with impurity have generated new perspectives and subtleties in the field of applied physics. This happens because of the interplay between various confinement sources with impurity potentials [2]. Out of various kinds of investigations on impurity doping, control of optoelectronic properties emerges as the central theme [3–15]. Naturally, we find a vast literature comprising of good theoretical studies on impurity states [16–21]. Added to this, there are also some excellent experimental works which include the mechanism and control of dopant incorporation [22, 23]. Driven by the emergence of novel experimental and theoretical techniques along with the existing ones, the research on carrier dynamics in nanodevices has become a ubiquitous field. The internal transitions between impurity-induced states in a QD led to research on carrier dynamics [8, 24]. These transitions depend on the spatial restriction imposed by the impurity. A minute survey of the above dynamical features directs us to explore excitation of electrons strongly confined in QD’s. Analysis on this aspect deems importance since it offers us model systems for use in optoelectronic devices and as lasers. In connection with the technological applications, excitation in
Raman continuum in high-$T_c$ superconductors
Haranath Ghosh,Manas Sardar
Physics , 1996, DOI: 10.1016/0921-4526(96)00168-8
Abstract: Experimentally, Raman continuum for $A_g$ and $B_g$ geometry exhibits peaks far apart from each other (about 80 to 150 $\rm cm^{-1}$) in frequency. The former is insensitive to doping over a small range where $T_c$ does not vary much whereas the latter shifts towards higher frequencies. We calculate the electronic Raman scattering intensities using the `modified spin bag model'. We show that the calculated results have natural explanation to the observed anamolous peak separation and peculiar doping dependence.
Characterization of a Novel MDH1 Bacterium from a Virgin Hot Spring Applicable for Gold Nanoparticle (GNPs) Synthesis  [PDF]
Nurul Alam, Manas Sarkar, Trinath Chowdhury, Dipak Ghosh, Brajadulal Chattopadhyay
Advances in Microbiology (AiM) , 2016, DOI: 10.4236/aim.2016.69071
Abstract: Background: Use of novel microorganisms for beneficial purposes is still remaining a challenging job. This study was designed to isolate, characterize and use of a novel hot spring bacterial strain from a virgin hot spring of Metaldanga, Birbhum, West Bengal, India. Methods: A pure bacterial strain (MDH1) was identified by growing the enrichment culture isolated from Metaldanga hot spring through serial dilution process in a semi-synthetic medium at pH 8.0 and 42°C temperature. The novelty of the strain was characterized by 16S-rRNA gene sequence analysis. The bacterium acted as template to synthesize spherical gold nanoparticles (GNPs). GNPs were characterized by using UV-Vis spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS) and Fourier transform infra-red spectroscopy (FTIR). Results: The phylogenetic analysis suggested that MDH1 strain (GenBank accession number: KT600031) was affiliated to the family “Pseudomonadaceae” with 99% homologous to Pseudomonas putida H8234. The coccoid shaped bacterium was gram-negative and facultative-anaerobic which acted as a template to synthesize spherical GNPs with an average size of 12 ± 3 nm when examined under transmission electron microscopy (TEM). FT-IR studies revealed the presence of bioactive functional groups which acted as capping and stabilizing agents of the GNPs. XRD pattern confirmed the amorphous nature of GNPs. The Zeta potential (ζ) concluded the adequate stability of GNPs in an aqueous environment. Conclusions: The present investigation explores the microbial diversity of a virgin hot spring of Metaldanga for its beneficial applications in industry, particularly in the synthesis of the gold nanoparticles.
Impurity Modulated Static Linear and First Nonlinear Polarizabilities of Doped Quantum Dots
Nirmal Kr Datta,Manas Ghosh
ISRN Optics , 2012, DOI: 10.5402/2012/847532
R parity violating supersymmetric explanation for the CDF Wjj excess
Dilip Kumar Ghosh,Manas Maity,Sourov Roy
Physics , 2011, DOI: 10.1103/PhysRevD.84.035022
Abstract: Recently CDF has reported a 4.1 sigma excess in the distribution of the dijet invariant mass between 120-160 GeV in Wjj event sample in 7.3 fb^{-1} of data, which has generated considerable interest. We offer a possible explanation of this observation in the general framework of MSSM with R-parity violation through resonance production of tau sneutrino decaying into the LSP stau_1 and W boson. We also give the predictions of this scenario for the LHC operating at 7 TeV center of mass energy.
Development and in vitro evaluation of Letrozole loaded biodegradable nanoparticles for breast cancer therapy
Dey, Sanjoy Kumar;Mandal, Bivash;Bhowmik, Manas;Ghosh, Lakshmi Kanta;
Brazilian Journal of Pharmaceutical Sciences , 2009, DOI: 10.1590/S1984-82502009000300025
Abstract: the objectives of our study were to prepare and evaluate a biodegradable nanoparticulate system of letrozole (ltz) intended for breast cancer therapy. ltz loaded poly(lactide-co-glycolide) nanoparticles (ltz-plga-nps) were prepared by emulsion-solvent evaporation method using methylene chloride and polyvinyl alcohol. percentage of drug (with respect to polymer) was selected as formulation variable. ltz-plga-nps were characterized by particle size, zeta potential, infrared spectra, drug entrapment efficiency and in vitro release. sonication was done with an ultrasound pulse sonicator at 70 w, 30 khz for 90 sec to produce stable nps of mean size range from 64 nm to 255 nm with high entrapment efficiency (68% to 82%). percentage of drug significantly influenced particle size, entrapment efficiency and release (p <0.05). the system sustained release of ltz significantly and further investigation could exhibit its potential usefulness in breast cancer therapy.
Evaluation of registered visually disabled individuals in a district of West Bengal, India
Ghosh Sambuddha,Mukhopadhyay Subhalakshmi,Sarkar Krishnendu,Bandyopadhyay Manas
Indian Journal of Community Medicine , 2008,
Abstract: Objective: To identify the sociodemographic characteristics, degree and cause of visual disability among certified visually disabled individuals in a rural district of West Bengal, India and to identify possible lacunae, if any, in the existing certification system. Materials and Methods: A cross-sectional study by secondary data analysis of medical records of 155 visually disabled individuals and their 310 eyes. Demographical features, diagnosis, percentage of visual disability and work activity status of each individual were analyzed. Results: One hundred and thirty one (84.52%) individuals had 100% disability. The number of males was significantly higher than that of females. Fifty eight (37.42%) individuals were below 21 years of age. Phthisis bulbi was the most common cause followed by microphthalmos. Further, 81.29% patients had the same lesion bilaterally. Conclusion: Patients with higher grades of disability have attended certification boards. A large number of disabled individuals comprised children and young adults. Male gender bias demands concern.
Excitation Kinetics of Impurity Doped Quantum Dot Triggered by Gaussian White Noise
Suvajit Pal,Sudarson Sekhar Sinha,Jayanta Ganguly,Manas Ghosh
ISRN Condensed Matter Physics , 2013, DOI: 10.1155/2013/798153
Abstract: We investigate the excitation kinetics of a repulsive impurity doped quantum dot initiated by the application of Gaussian white noise. In view of a comprehensive research we have considered both additive and multiplicative noise (in Stratonovich sense). The noise strength and the dopant location have been found to fabricate the said kinetics in a delicate way. Moreover, the influences of additive and multiplicative nature of the noise on the excitation kinetics have been observed to be prominently different. The investigation reveals emergence of maximization and saturation in the excitation kinetics as a result of complex interplay between various parameters that affect the kinetics. The present investigation is believed to provide some useful perceptions of the functioning of mesoscopic systems where noise plays some profound role. 1. Introduction Throughout last couple of decades we came across a tremendous surge in theoretical and experimental researches on impurity states of low-dimensional heterostructures [1]. Among these heterostructures, quantum dots (QDs) have been found to take some leading role undoubtedly. The importance of QD originates because of its emergence as the destination in the journey towards miniaturization of semiconductor devices. Furthermore, the properties of doped QDs have made them potential candidates for scientific study and technological applications. With QD, the subtle interplay between new confinement sources and impurity potentials has opened up new areas of research in this field [2]. Under the confinement, the dopant location can tailor the electronic and optical properties of the system [3]. This resulted in a rich literature comprising of theoretical studies on impurity states [4–7] in general, and also on their optoelectronic properties, in particular, for a wide range of semiconductor devices [3, 8–15]. The widespread research trend elegantly explores new physics and indicates profound technological impact simultaneously. As a natural extension of the trend, dynamical aspects of doped QD have also been extensively studied. Out of them researches on excitation of strongly confined electron merit importance because of the crucial role played by the said phenomenon in optoelectronic devices and as lasers. From the perspective of technological applications such excitation further involves optical encoding, multiplexing, and photovoltaic and light emitting devices. The phenomenon also plays some important role in the population transfer among the exciton states in QD [16]. Of late, we have performed some
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