Indian Institute of Technology Kharagpur

About: Indian Institute of Technology Kharagpur is a education organization based out in Kharagpur, India. It is known for research contribution in the topics: Natural rubber & Dielectric. The organization has 16887 authors who have published 38658 publications receiving 714526 citations.

Geochemical appraisal of fluoride contamination of groundwater in the Nayagarh District of Orissa, India

Abstract: The occurrence of high concentrations of fluoride in groundwater (>1.5 mg/l) in the villages of Singhpur and Sagaragan in the Nayagarh District of Orissa and its relation with the fluoride-rich hot spring water (>10 mg/l) located nearby have been studied. The composition of the hot spring water is very comparable to the other thermal waters of the world. Thermodynamic considerations show that more than 65% of the groundwater and hot spring water samples are oversaturated with calcite, and only four samples are oversaturated with fluorite. Fluoride concentration shows a positive relation to sodium, bicarbonate and pH, and a negative relation to calcium and magnesium in fluoride-rich groundwater and hot spring water. Principal component analysis shows that the fluoride-rich groundwater was produced due to a mixing of hot spring water with the surrounding groundwater. Studies of the saturation index of fluorite with log electrical conductivity also indicate mixing of hot spring water with the surrounding groundwater. The spatial distribution of fluoride in groundwater follows the topography of the area.

Validation and application of a novel elongational device for polymer solutions

Abstract: A novel elongational device is used to investigate the capillary thinning process of threads of dilute and semidilute aqueous polymer solutions. It is shown that the end regions of the threads do not play an essential role in the thinning process, so that a simple theory describing the self-thinning of the liquid thread is appropriate to describe the experiments with polymer solutions carried out with this device. Aqueous solutions of four different polymers (all polyacrylamide based) are studied using the elongational device. It is shown that the elasticity of the polymers is dominated by polyacrylamide chains and that the effect of branching and topological structure of macromolecules is negligible. The time-dependent decrease of the thread diameter can be divided into two stages. The first is a viscoelastic one where macromolecular coils are stretched by the elongational flow, and the second is a quasi-Newtonian one, where full stretching has already been achieved, resulting in a very high but constant...