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Alwar, India

Vishwakarma J.P.,rakhpur University | Nath G.,National Institute of Technology Raipur
Physica Scripta | Year: 2010

A self-similar solution for the propagation of a cylindrical shock wave in a dusty gas with heat conduction and radiation heat flux, which is rotating about the axis of symmetry, is investigated. The shock is assumed to be driven out by a piston (an inner expanding surface) and the dusty gas is assumed to be a mixture of non-ideal gas and small solid particles. The density of the ambient medium is assumed to be constant. The heat conduction is expressed in terms of Fourier's law and radiation is considered to be of diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature and density. Similarity solutions are obtained, and the effects of variation of the parameter of non-idealness of the gas in the mixture, the mass concentration of solid particles and the ratio of density of solid particles to the initial density of the gas are investigated. © 2010 The Royal Swedish Academy of Sciences. Source

Yadav A.K.,Anand Engineering College | Yadav L.,rakhpur University
International Journal of Theoretical Physics | Year: 2011

The Bianchi type III dark energy model with constant deceleration parameter is investigated. The equation of state parameter ω is found to be time dependent and its existing range for this model is consistent with the recent observations of SN Ia data, SN Ia data (with CMBR anisotropy) and galaxy clustering statistics. The physical aspects of the dark energy models is discussed. © 2010 Springer Science+Business Media, LLC. Source

Singh R.P.,St Andrews College | Yadav L.,rakhpur University
Romanian Reports in Physics | Year: 2011

A new class of a spatially homogeneous and anisotropic Bianchi type-V cosmological models of the Universe for bulk viscous fluid distribution within the framework of general relativity is investigated by applying the law of variation for the generalized mean Hubble's parameter that yields a constant value of deceleration parameter. The variation for Hubble's parameter generates two types of solutions for the average scale factor one is of power-law type and other is of the exponential form. Using these two forms, Einstein's field equations are solved separately that correspond to singular and non-singular models of the Universe respectively. It is observed that for positive value of deceleration parameter q of the Universe decelerates whereas for negative value of q the Universe accelerates. Expressions for look-back time-redshift, neoclassical tests (proper distance d(z)), luminosity distance red-shift and event horizon are derived and their significance are described in detail. Some physical and geometrical properties of the models are also discussed. Source

Botet R.S.,French National Center for Scientific Research | Rai R.K.,rakhpur University
Earth, Planets and Space | Year: 2013

We present optical features characteristic of the shape of composite dust particles, such as grain-aggregates formed under cosmic or atmospheric conditions. The discussion develops along two examples of realistic models for the formation of the composite particles, and constant refractive indices. That way, particular features exhibited in the optical cross section behaviors result from the particle structure only. The role of the ratio between optical particle cross section and the corresponding cross section of the coated sphere of same composition and volume is highlighted. Limited wavelength ranges are defined where the coated sphere model can be used to obtain the effective radius or the volume composition of the particle. Other wavelength domains are very dependent on the particle formation mechanisms, then giving constraints on the possible formation processes. Therefore, such an approach is able to provide inverse methods to obtain the actual values of physical parameters from definite features of optical quantities. © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS);. Source

Joshi D.,Jiwaji University | Mittal D.,Jiwaji University | Shrivastav S.,Jiwaji University | Shukla S.,Jiwaji University | Srivastav A.K.,rakhpur University
Archives of Environmental Contamination and Toxicology | Year: 2011

Mercury (Hg), widely used in industry, is a great environmental health problem for humans and animals. Despite several reports regarding Hg toxicity, there is scarcity of data on its toxic manifestations on Sprague Dawley rats under realistic exposure conditions. Experimental studies have shown that sulphur-containing antioxidants have beneficial effects against the detrimental properties of Hg. The present work was aimed to study the therapeutic potential of combined administration of N-acetyl cysteine (NAC; 2 mmol/kg ip), zinc (Zn; 2 mmol/kg po), and selenium (Se; 0.5 mg/kg po) against dimethylmercury (DMM; 1 mg/kg po)-intoxicated male rats for 12 weeks. Exposure to DMM caused significant alterations in cytochrome P450 (CYP) activity, microsomal lipid peroxidation, and proteins. Activities of transaminases (aspartate aminotransferase/alanine aminotransferase), alkaline phosphatase, and lactate dehydrogenase in serum, as well as activities of CYP enzymes aniline hydroxylase (AH), amidopyrine-N- demethylase (AND) in liver microsomes and activities of acid phosphatase, alkaline phosphatase, glucose-6-phophatase, and succinic dehydrogenase in the liver and kidney, were significantly altered after DMM administration. DMM exposure also induced severe hepato-renal alterations at the histopathological level. NAC, along with Zn and Se, dramatically reversed the alterations in all of the variables more toward control. The study results conclude that protective intervention of combined treatment of NAC, along with Zn and Se, is beneficial in attenuating DMM-induced systemic toxicity. © 2011 Springer Science+Business Media, LLC. Source

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