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Search Results: 1 - 10 of 491267 matches for " S. R. Das "
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Radiation Effect on Natural Convection Near a Vertical Plate Embedded in Porous Medium with Ramped Wall Temperature  [PDF]
S. Das, M. Jana, R. N. Jana
Open Journal of Fluid Dynamics (OJFD) , 2011, DOI: 10.4236/ojfd.2011.11001
Abstract: Radiation effect on the natural convection flow of an optically thin viscous incompressible fluid near a vertical plate with ramped wall temperature in a porous medium has been studied. The exact solution of momentum and energy equations is obtained by the use of Laplace transform technique. The variations in fluid velocity and temperature are shown graphically whereas the numerical values of shear stress and the rate of heat transfer at the wall are presented in tabular form for various values of flow parameters. The results show that the fluid velocity increases with increase in Grashof number, Darcy number and time parameters whereas the fluid velocity decreases with increase in the radiation parameter and Prandtl number for ramped temperature as well as isothermal wall temperature. It is found that an increase in radiation parameter leads to rise the temperature for both ramped wall temperature as well as isothermal wall temperature. Further, it is found that an increase in Prandtl number leads to fall the temperature for both ramped wall temperature as well as isothermal wall temperature. The shear stress at the wall decreases with increases in either Prandtl number or porosity parameter while the result shows reverse in the case of radiation parameter. Finally, the rate of heat transfer is increased with increases in the radiation parameter for both ramped wall temperature as well as isothermal wall temperature.
Effective Beneficiation of Low Grade Iron Ore Through Jigging Operation  [PDF]
B. Das, S. Prakash, S.K. Das, P.S.R. Reddy
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2008, DOI: 10.4236/jmmce.2008.71002
Abstract: The effectiveness of jigging operation for the beneficiation of low-grade iron ore deposits of Orissa, India has been investigated. Iron ore sample obtained from Barbil region of Orissa containing very high amount of silica and alumina was crushed using the laboratory jaw crusher and roll crusher to prepare different particle sizes. The sink and float tests were carried out to evaluate the possible response of the sample by gravity concentration technique. The samples were subjected to jigging in a laboratory Denver mineral jig and Harz jig. The operating variables used to determine the effectiveness of jigging include, particle size, velocity of water and amplitude. Recovery of iron values and the separation efficiency were assessed by determining mineralogy and the percentages of Fe in the jig concentrate and tailings by wet chemical and X-ray floroscence (XRF) techniques. Optimum iron ore recovery of 78.6% was achieved with 63.7% Fe in concentrate when the jig was operated at medium stroke, with an average water velocity and at a particle size of below 5 mm. The results are very close to theoretical results obtained by sink and float studies.
Evaluation of Type of Nephropathy in Patients of Type-2 Diabetes Mellitus  [PDF]
S. Nayak, S. K. Tripathy, S. Das, B. P. Das, C. R. Kar
Journal of Diabetes Mellitus (JDM) , 2017, DOI: 10.4236/jdm.2017.74023
Abstract: Background of the Study, Aims and Objectives: There are very few studies on histological patterns of diabetic nephropathy in our part of country. The aim of this study was to evaluate the renal involvement in patients with Type-2 diabetes mellitus (T2DM), assess the histopathological changes and establish a clinico-pathological correlation. Subjects, Method and Materials: Thirty two Type 2 DM patients with nephropathy, after screening consecutive hundred(100) Type 2 Diabetics admitted to the Medicine Department were evaluated for renal involvement by kidney biopsy and histopathological study. Statistical analysis was done by student’s t-test, chi-square and linear regression analysis. Results: Thirty two patients (32) with diabetic nephropathy (20 males and 12 females) formed the study group out of hundred (100) consecutive Type-2 diabetes mellitus patients (58 males and 42 females) admi
R. S. Das et al.
International Journal of Pharmaceutical Sciences and Research , 2012,
Abstract: This paper describes the study to measure the sensitivity and accuracy of two techniques, chromatography and spectrophotometry for the direct determination of citalopram in pharmaceutical formulations. Chromatography was performed on SE-30 column (1 m × 3 mm i.d) using Nitrogen as a carrier gas (flow rate of 40 ml/min), having retention time of 12.8 min. Calibration curve was found linear in the range of 200-400 μg/ml. LOD and LOQ values were found as 1.1726 μg/ml and 3.5535 μg/ml respectively and the recoveries were in the range of 98.36–100.07%. In spectrophotometry method the absorption spectra were measured at 240 nm for standard and tablets form. Calibration curve was found linear in the range of 2-4 μg/ml. LOD and LOQ values were found as 40.59 ng/ml and 123.0 ng/ml respectively. Recoveries were in the range of 98.53–100.78%. The experimental results obtained indicate that the above proposed methods are specific, sensitive and accurate for the determination of citalopram in pharmaceutical formulations. These methods were also compared statistically and found that there was no significant difference between the two methods in terms of accuracy and precision. Whilst, the chromatographic method developed will applicable for its detection in biological matrices also.
Persistent Current in an Artificial Quantum Dot Molecule
R. Kotlyar,S. Das Sarma
Physics , 1996, DOI: 10.1103/PhysRevB.55.R10205
Abstract: Using an exact diagonalization technique within a generalized Mott-Hubbard Hamiltonian, we predict the existence of a ground state persistent current in coherent two-dimensional semiconductor quantum dot arrays pierced by an external magnetic flux. The calculated persistent current, which arises from the nontrivial dependence of the ground state energy on the external flux, exists in isolated arrays without any periodic boundary condition. The sensitivity of the calculated persistent current to interaction and disorder is shown to reflect the intricacies of various Anderson-Mott-Hubbard quantum phase transitions in two dimensional systems.
Nonlinear Transport through Coupled Double Quantum Dot Systems
R. Kotlyar,S. Das Sarma
Physics , 1996, DOI: 10.1103/PhysRevB.56.13235
Abstract: We investigate sequential tunneling transport through a semiconductor double quantum dot structure by combining a simple microscopic quantum confinement model with a Mott-Hubbard type correlation model. We calculate nonperturbatively the evolution of the Coulomb blockade oscillations as a function of the interdot barrier conductance, obtaining good qualitative agreement with the experimental data over the whole tunneling regime from the weak-coupling individual dot to the strong-coupling coherent double-dot molecular system.
Disorder and Interaction in 2D: Exact diagonalization study of the Anderson-Hubbard-Mott model
R. Kotlyar,S. Das Sarma
Physics , 2000, DOI: 10.1103/PhysRevLett.86.2388
Abstract: We investigate, by numerically calculating the charge stiffness, the effects of random diagonal disorder and electron-electron interaction on the nature of the ground state in the 2D Hubbard model through the finite size exact diagonalization technique. By comparing with the corresponding 1D Hubbard model results and by using heuristic arguments we conclude that it is \QTR{it}{unlikely} that there is a 2D metal-insulator quantum phase transition although the effect of interaction in some range of parameters is to substantially enhance the non-interacting charge stiffness.
Nutrition in Relation to Diseases and Heat stress in Poultry
S Das,T K Palai,S R Mishra,D Das
Veterinary World , 2011,
Abstract: Different diseases conditions and stress factors are responsible for high morbidity and mortality of present day poultry. Nutritional strategy and proper feed formulation with specific dietary regimen can combat this up to a certain extent. The incidence of various infectious diseases, nervous disorders and metabolic disorders can be minimized through proper feed regimen. There is a stiff competition and restrictions in the global market of poultry products which can be addressed with proper management of emerging and important diseases with economic productions and quality poultry products free of elements detrimental to human health. Researchers have made efforts to prevent such damage to poultry and poultry product through dietary manipulations. Heat stress can lead to a reduction in the defense mechanisms of birds or to a relative state of immunosuppression. The health status of the poultry is facing new challenges today which can be suitably addressed by the right scientific and advanced nutritional manoeuvres and make the poultry farming more profitable and presentable in the global market. [Vet. World 2011; 4(9.000): 429-432]
Enteric pathogens in north Indian patients with diarrhoea
Das S,Saha R,Singhal S
Indian Journal of Community Medicine , 2007,
Abstract: Background : Diarrhoeal diseases are a leading cause of morbidity and mortality among children in developing countries requiring hospitalisation. AIDS and indiscriminate use of antibiotics have further worsen the condition. Objectives : To assess the etiological agents causing diarrhea with the aim to limit indiscriminate use of antimicrobial agents. Methods : A cross-sectional study was done involving children and adults (of all age groups) suffering from gastrointestinal infection attending the OPD or admitted to Guru Teg Bahadur Hospital. The study was analysed using chi-square test and crosstab chi-square test. Results : Of the 2534 stool samples processed, 23.2% were positive for pathogens. 4.6% were positive for Shigella species, 2.37% for Salmonella species and 1.5% for Escherichia coli (E.coli). Vibrio cholerae OI El Tor serotype Ogawa (82.55%) was more common than serotype Inaba (19.5%). Vibrio cholerae strains were generally resistant to all drugs except Ciprofloxacin, Gentamicin, and Cefotaxime. Multidrug resistant Shigella and Salmonella species was also an important observation made. However parasitic and viral (rota virus) associated diarrhea did not exceed the bacterial causes. Conclusions : New pathogens have emerged as causative organisms of diarrhoa. Indiscriminate use of antibiotics can lead to drug resistance necessitating monitoring of drug susceptibility and formulation of drug policy in hospitals.
Disseminated nodular granulomatous perifolliculitis
Das S,Saha R,Bhattacharya S
Indian Journal of Medical Microbiology , 2007,
Abstract: Nodular granulomatous perifolliculitis is a well-recognized infection of the dermal and subcutaneous tissue caused by dermatophytes, which normally do not invade beyond the epidermis. We report here one such case that occurred in an immunosuppressed individual. The patient was a 35-year-old farmer who presented with small pruritic eruption that had initially appeared on the lower leg and then had gradually spread to hair-bearing areas of the body, finally producing nodular and pustular inflammatory lesions with exacerbations and remissions. Fungal examination by direct potassium hydroxide mount and culture revealed Trichophyton rubrum. Granulomatous changes were seen on histopathological examination. The patient completely responded to systemic antifungal therapy.
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