Indian Institute of Technology Ropar

About: Indian Institute of Technology Ropar is a education organization based out in Ropar, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 1014 authors who have published 2878 publications receiving 35715 citations.

Cosmic structure sizes in generic dark energy models

Abstract: The maximum allowable size of a spherical cosmic structure as a function of its mass is determined by the maximum turn around radius $$R_\mathrm{TA,max}$$ , the distance from its center where the attraction on a radial test particle due to the spherical mass is balanced with the repulsion due to the ambient dark energy. In this work, we extend the existing results in several directions. (a) We first show that, for $$w e -1$$ , the expression for $$R_\mathrm{TA, max}$$ found earlier, using the cosmological perturbation theory, can be derived using a static geometry as well. (b) In the generic dark energy model with arbitrary time dependent state parameter w(t), taking into account the effect of inhomogeneities upon the dark energy as well, it is shown that the data constrain $$w(t=\mathrm{today})>-2.3$$ . (c) We address the quintessence and the generalized Chaplygin gas models, both of which are shown to predict structure sizes consistent with observations.

Nitrogen-doped carbon nanotubes for sensitive and selective determination of heavy metals

Abstract: The present study attempts to demonstrate the potential of nitrogen-containing carbonaceous materials towards electrochemical determination of heavy metal ions. For this purpose, nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized from post treatment of oxidized carbon nanotubes (O-CNTs) in the presence of NH3 at three different temperatures of 200, 400 and 600 °C to analyse their relevance in heavy metal ions determination. The electrocatalytic activity of these materials towards determination of Cd, Pb and Cu metal ions was examined by means of the square wave stripping voltammetry (SWSV) technique which demonstrates the suitability of all temperature variants for the desired purpose. Eventually, N-CNTs treated at 600 °C (N-CNT 600) displayed comparatively better sensitivity towards the investigated heavy metal ions (Cd, Pb and Cu) as compared to the other temperature variants of the N-CNTs (N-CNT 200 and N-CNT 400). The role of nitrogen groups was assessed in comparison with O-CNTs as it eliminates the requirement of the pre-concentration step by efficient complexation with heavy metal ions. The peak current for the Pb and Cd metal ions increased linearly in the concentration range of 0.01 μM–70 μM and 0.1 μM–100 μM respectively (individual as well as simultaneous determination). The limit of detection (LOD) was calculated to be 0.001 μM and 0.005 μM (3σ method) for the simultaneous determination of Pb and Cd metal ions respectively. Furthermore, a real time application of a N-CNT 600 modified GCE was probed by electrochemical detection of Cd and Pb metal ions in tap water and ground water.

Biocompatible High Entropy Alloys with Excellent Degradation Resistance in a Simulated Physiological Environment

Abstract: Bioimplants are susceptible to simultaneous wear and corrosion degradation in the aggressive physiological environment. High entropy alloys with equimolar proportion of constituent elements represe...