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R. K. Nath ¹, A. Chakrabarti ¹, A. K. Chakraborty ¹

Affiliations
1 Department of Chemistry, Calcutta University Post Graduate Centre, Agartala, Tripura-799004, IN

Abstract

Interaction of cationic dye pinacyanol chloride with bacterial cell surface capsular polysaccharide isolated from Klebsiella K40 has been spectrophotometrically Investigated. The capsular polysaccharide of Klebsiella K40 is a heteroglycan which consists of pentasaccharide repeating units comprising one residue each of unsubstituted mannose, 4-substituted glucuronic acid, 3-substituted galactose, 2, 4-disubstituted rhamnose, and 2-substituted rhamnose. It Induces a metachromatic blue shift in the visible spectrum of the pinacyanol chloride from 600 nm to 500 nm. The metachromatic spectral changes have been studied during interaction of the dye cation with the polyanion at different polymer/dye molar ratios. A stochiometry of 11 for the polymer/dye has been found to exist in the polyanion-dye compound. The complete reversal of polymer-induced metachromasy has also been observed by the addition of ethanol and urea.

Keywords

Pinacyanol Chloride, Poly Saccharide, Metachromasy.

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K. S. Subramanian ¹, S. K. Bhattacharya ², Prosenjit Ghosh ², A. Chakrabarti ³

Affiliations
1 Plot 283, 17th East Street, Kamraj Nagar, Tiruvenmiyur, Chennai - 600041, IN
2 Physical Research Laboratory, Ahmedabad - 380 009, IN
3 Indian Institute of Technology, Kharagpur - 721 302, IN

Abstract

No Abstract.

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A. C. Narayana ¹, C. P. Priju ¹, A. Chakrabarti ²

Affiliations
1 Department of Marine Geology and Geophysics, Cochin University of Science and Technology, Lakeside Campus, Kochi - 682 016, IN
2 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur - 721 302, IN

Abstract

No Abstract.

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S. K. Bhattacharya ¹, Prosenjit Ghosh ¹, A. Chakrabarti ²

Affiliations
1 Physical Research Laboratory, Ahmedabad - 380 009, IN
2 Indian Institute of Technology, Kharagpur - 721 302, IN

Abstract

Ubiquitous presence of carbonate rich nodules in glaciogene sediments of various Permo-Carboniferous basins (Talchir) in peninsular India offers promise for delineating the climatic condition and environment of deposition at that time. Isotopic composition of carbon and oxygen have been determined in carbonate nodules collected from the basal formation (Talchir) of three Gondwana basins of east-central India along with a few samples from contemporaneous Dwyka tillite of South Africa. Petrographic, cathodoluminescence and sedimentary evidences suggest that many of these nodules contain primary carbonate precipitates and therefore their geochemical signatures can be used for palaeoclimatic inference. The mean δ¹⁸0 and δ¹³C values of the calcites in the nodules are 10.8% w.r.t. SMOW and - 9.7%0 w.r.t. PDB respectively, suggesting a freshwater environment (probably lacustrine) for formation of these concretions. The mean oxygen isotopic composition of meteoric water at that time (Early Permian) and location (70° S palaeolatitude) estimated from δ¹⁸Oof calcite is -22.7%0 and is depleted by a few per mil from the expected isotopic composition of precipitation at this latitude. This depletion can be interpreted either in terms of an amount effect due to enhanced rainfall or an altitude effect if the precipitation occurred at high altitude (as expected for development of the Talchir glacier).

Keywords

Carbon and Oxygen isotopes, Carbonate concretions, Talchir formation, Eastern India.

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