Gulbarga, India
Gulbarga, India

Gulbarga University is a public university located in Gulbarga, Karnataka, India. Its jurisdiction extends to the four districts of Gulbarga District, Bidar District, Raichur District, and Yadgir District of Karnataka. It has more than 37 teaching departments and 4 research centres and also acts as an affiliating university. Wikipedia.


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Shrinivas D.,Gulbarga University | Naik G.R.,Gulbarga University
International Biodeterioration and Biodegradation | Year: 2011

A thermostable alkaline protease produced from Bacillus sp. JB 99 exhibited significant keratinolytic and dehairing activity. The enzyme was purified by ammonium sulphate precipitation followed by CM-cellulose and Sephadex G-100 chromatography and resulted in 13.6 fold purification with 23.8% of recovery. The specific activity of purified enzyme was 2989.6Umg-l. Purified protease had a molecular weight of 29kDa and appeared as a single band. Gelatin zymogram analysis also revealed a clear hydrolytic zone, which corresponded to the band obtained with SDS-PAGE. The optimum pH and temperature for the keratinolytic activity was pH 11.0 and 70°C respectively and half life of protease was 70°C for 4h. N-terminal amino acid sequence of purified enzyme exhibited extensive homology with other thermostable alkaline proteases and inhibition by PMSF indicated serine type of protease. The Km and Vmax of protease for keratin substrate were 3.8±0.5mgml-1 and 15.1±1.6μmmin-1mg-1 and casein were 3.3±0.4mgml-l and 15.6±0.9μmmin-1mg-1 respectively. The enzyme efficiently dehaired buffalo and goat hide without damaging the collagen layer, which makes it a potential candidate for application in leather industry to avoid pollution problem associated with the use of chemicals in the industry. The enzyme also degraded chicken feathers in presence of reducing agent which can help poultry industry in management of keratin-rich waste and obtaining value added products. © 2010 Elsevier Ltd.


A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes have been synthesized with newly synthesized Schiff base derived from naphthofuran-2-carbohydrazide and cinnamaldehyde. The elemental analyses of the complexes are confined to the stoichiometry of the type MLCl2 [M = Co(II) and Cu(II)], ML2Cl2 [M = Ni(II), Cd(II), Zn(II) and Hg(II)] respectively, where L is Schiff base ligand. Structures have been proposed from elemental analyses, IR, electronic, mass, 1H NMR, ESR spectral data, magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Spectroscopic studies suggest coordination occurs through azomethine nitrogen and carbonyl oxygen of the ligand with the metal ions. The Schiff base and its complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium and Candida albicans) activities by minimum inhibitory concentration (MIC) method. The DNA cleavage studies by agarose gel electrophoresis method was studied for all the complexes. © 2012 Elsevier B.V. All rights reserved.


Uma Reddy B.,Gulbarga University
E-Journal of Chemistry | Year: 2010

The present study was aimed to investigate the antibacterial activity of some common locally available plants, in order to estimate the biological potential of these herbs. The alcoholic extract of Tagetes erecta L (Asteraceae), Argemone mexicana L (Papavaraceae), Datura stramonium L. (Solanaceae) and Tylophora indica (Burm.f.) Merr. (Asclepiadaceae) were evaluated for antibacterial activity using broth dilution bioassay method. It is clear from the results that, the extracts of these plants acts as a good source of antibiotics against various bacterial pathogens tested and exhibited broad spectrum of antibacterial activity. These plant extracts were shown to be moderate to maximum inhibitory effect against different bacterial forms such as Salmonella typhii, Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli, where as, mild to moderate activity against Klebsiella pneumoniae and Staphylococcus aureus. The results of these studies revealed most valuable information and also support the continued sustainable use of these plants in traditional systems of medicine.


Malashetty M.S.,Gulbarga University | Biradar B.S.,Gulbarga University
Physics of Fluids | Year: 2011

The onset of double diffusive reaction-convection in a horizontal anisotropic porous layer saturated with binary mixture, which is heated and salted from below and subjected to chemical equilibrium on the boundaries, is studied analytically using both linear and nonlinear stability analyses. A linear stability analysis is performed to investigate how the dissolution or precipitation of reactive component affects the onset of convection. The Darcy model is employed as momentum equation. The effect of mechanical and thermal anisotropy parameters, reaction rate, Lewis number, solute Rayleigh number, and normalized porosity on the stability of the system is investigated. We find that the chemical reaction may be stabilizing or destabilizing and that the anisotropic parameters have significant influence on the stability criterion. The effect of various parameters on the stationary, oscillatory, and finite amplitude convection is shown graphically. A weak nonlinear theory based on the truncated representation of Fourier series method is used to find the finite amplitude Rayleigh number and heat and mass transfer. © 2011 American Institute of Physics.


Malashetty M.S.,Gulbarga University | Swamy M.S.,Government College
Physics of Fluids | Year: 2011

The combined effect of gravity modulation and rotation on the onset of thermal convection in a horizontal fluid layer and a fluid-saturated porous layer is studied analytically using linear stability theory. The regular perturbation method based on small amplitude of modulation is employed to compute the critical value of Rayleigh number and wavenumber. We considered in the present paper only synchronous mode. The correction critical Rayleigh number is calculated as a function of Taylor number, Prandtl number, Darcy number, frequency of the modulation, normalized porosity, and viscosity ratio. It is shown that in general the gravity modulation produces a stabilizing effect in case of viscous fluid layer and both destabilizing and stabilizing effects in case of Brinkman porous layer while it produces a destabilizing effect in case of Darcy porous layer. The low frequency gravity modulation is found to have a significant effect on the stability of the system. It is shown that the onset of convection can be advanced or delayed by proper tuning of various governing parameters. The results of Darcy limit and viscous flow limit are derived as the degenerate cases of Brinkman model. © 2011 American Institute of Physics.


Umavathi J.C.,Gulbarga University
International Journal of Heat and Mass Transfer | Year: 2015

Free convection over a vertical rectangular duct filled with porous matrix with variable viscosity and variable thermal conductivity is studied in this paper. We consider the two-dimensional steady laminar flow and Brinkman-Forchheimer extended Darcy model to define the porous medium. Using the appropriate variables the basic governing equations are transformed to non-dimensional governing equations. The fluid viscosity is assumed to vary exponentially with temperature whereas the thermal conductivity is assumed to vary linearly with temperature. One of the vertical walls of the duct is cooled with constant temperature while the other wall is heated to constant but different temperature. The governing coupled nonlinear momentum and energy equations are solved numerically using finite difference method. The effect of pertinent parameters such as variable viscosity, variable thermal conductivity, Darcy number, inertial parameter, Grashof number, Brinkman number and aspect ratio on the velocity, temperature, volumetric flow rate, shear stress and heat transfer are discussed. © 2014 Elsevier Ltd.


Gayakwad R.,Gulbarga University
Acta Polytechnica Hungarica | Year: 2010

For any fuzzy logic application the first and foremost task is to select the optimum number and shape of membership functions such as bell shape, singleton, triangular, etc. for fuzzification; then it is equally essential to select the appropriate defuzzification method, such as COG, COM, MOM, etc. The sampling rate to execute the given command is another important parameter. If these three parameters are optimally selected then the output response of motion controller will have a shorter rise time, less settling time, minimized overshoots/undershoots and negligible steady state error. Hence, the systematic study on selection of number and shape of membership function, selection of defuzzification methods and sampling time for speed control of PMDC micro motor is studied experimentally by applying LabVIEW software. The experimental results reveal that 7 numbers of triangular membership functions, COG defuzzification method and 1 millisecond (msec) sampling rate for labVIEW program execution are the optimum parameters for motion control.


Biradar J.S.,Gulbarga University | Sasidhar B.S.,Gulbarga University
European Journal of Medicinal Chemistry | Year: 2011

A rapid, efficient and environmental benign methodology for the preparation of 2,5-disubstituted indole analogues is developed. 2,5-Disubstituted indole-3-carboxaldehydes (1a-c) undergo Knoevenagel condensation with barbiturates (2 & 4), thiazolidine-2,4-dione (6) and 3-methyl-1H-pyrazol- 5(4H)-one (8) in solvent-free, NH4OAc catalyzed, microwave assisted reaction. Structures of the products thus obtained were confirmed by their m.p, Elemental analysis, IR, 1H NMR, 13C NMR and Mass spectral data. The in vitro antioxidant and cytotoxic activities against three tumor cell lines were evaluated and discussed in terms of their structural differences. Among the screened compounds 9b, 9c, 7b and 5b exhibited excellent antioxidant activity. Compounds 9b, 9c and 7b have shown strong cytotoxicity among the compounds tested. © 2011 Elsevier Masson SAS. All rights reserved.


Umavathi J.C.,Gulbarga University
Transport in Porous Media | Year: 2013

Numerical investigation of steady natural convection flow through a fluid-saturated porous medium in a vertical rectangular duct is investigated. The Darcy-Forchheimer-Brinkman model is used to represent the fluid transport within the porous medium. One of the vertical walls of the duct is cooled to a constant temperature, while the other wall is heated to constant but different temperature. The other two sides of the duct are insulated. The finite difference method of second-order accuracy is used to solve the non-dimensional governing equations. The results are presented graphically to show the effects of the Darcy number, inertial parameter, Grashof number, Brinkman number, aspect ratio, and viscosity ratio. It is found that an increase in the Darcy number and inertial parameter reduces the flow intensity whereas an increase in the Grashof number, Brinkman number, aspect ratio, and viscosity ratio increases the flow intensity. © 2012 Springer Science+Business Media Dordrecht.


Umavathi J.C.,Gulbarga University
Transport in Porous Media | Year: 2013

The effect of time-periodic temperature modulation at the onset of convection in a Boussinesq porous medium saturated by a nanofluid is studied analytically. The model used for the nanofluid incorporates the effects of Brownian motion. Three types of boundary temperature modulations are considered namely, symmetric, asymmetric, and only the lower wall temperature is modulated while the upper wall is held at constant temperature. The perturbation method is applied for computing the critical Rayleigh and wave numbers for small amplitude temperature modulation. The shift in the critical Rayleigh number is calculated as a function of frequency of modulation, concentration Rayleigh number, porosity, Lewis number, and thermal capacity ratio. It has been shown that it is possible to advance or delay the onset of convection by time-periodic modulation of the wall temperature. The nanofluid is found to have more stabilizing effect when compared to regular fluid. Low frequency is destabilizing, while high frequency is always stabilizing for symmetric modulation. Asymmetric modulation and only lower wall temperature modulation is stabilizing for all frequencies when concentration Rayleigh number is greater than one. © 2013 Springer Science+Business Media Dordrecht.

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