Informatics Publishing Limited

Indranil Chakraborty ¹, S. P. Moulik ¹

Affiliations
1 Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032, IN

Abstract

The micelles of the anionic surfactants, sodium bis(ethyl-2-hexyl)sulphosuccinate (AOT) and sodium dodecylsulphate (SDS) have been used as templates for the preparation of CoS₂ nanoparticles. The S-S bond in CoS₂ was confirmed by the presence of the 480 cm^-1 sharp peak in the infra-red spectrum. The as-prepared material was characterized by UV-visible spectra and transmission electron microscopy (TEM). The prominent circular pattern in the selected area electron diffraction (SAED) study confirmed the crystalline structure of the materials prepared in either of the templates.

Keywords

CoS₂ Nanoparticle, Micellar Templates, Quantum Confinement, Optical Enhancement.

Full Text

     

Syamasri Gupta ¹, S. P. Moulik ¹

Affiliations
1 Department of Physical Chemistry, Jadavpur University, Calcutta-32, IN

Abstract

Conformation changes of the biopolymer amylose in different environments have been evaluated through hydrodynamic parameters. In presence of additives, conformational change is not the sole factor for complexation with iodine : specific solvent effects are present. Aqueous KI solution fails to extract iodine from the complex by dialysis but benzene can extract a part of it. Surfactants, above their critical micelle concentrations, can significantly destabilise the complex. These results and the effect of temperature on the complex reveal that major part of the iodine is strongly bound and the rest is weakly bonnd to amylose.

Full Text

     

K. N. Jalan ¹, M. L. Chakraborty ¹, S. K. Agarwal ¹, T. Samanta ¹, D. Mahalanobis ¹, D. K. Chattoraj ², S. P. Moulik ²

Affiliations
1 Kothari Centre of Gastroenterology, Calcutta Medical Research Institute, Calcutta-700 027, IN
2 Department of Food Technology and Biochemical Engineering and Department of Chemistry, Jadavpur University, Calcutta-700 032, IN

Abstract

The intrinsic stability of human bile as well as the stability of model and natural bile in different salt environments were studied. The results suggested that irrespective of its cholesterol content, human bile was unstable and exhibited spontaneous precipitation of its three major components, cholesterol, phospholipids and bile salts. The extent of precipitation of each component varied from sample to sample. Salts imparted instability to the bile and cations of higher valancy were more effective. Multivalent cation, Ca⁺⁺, Mg⁺⁺ and Fe⁺⁺⁺ caused partial precipitation of all the three components of the model as well as the natural bile. The multivalent protein protamine sulphate was also a much effective precipitant. The precipitation by the electrolytes followed the Hardy-Shulze valency rule observed for hydrophobic colloids according to which the power of precipitation by an electrolyte depends on its ion carrying charge opposite in sign to that of the colloid. The effectivity followed the order: protamine sulphate>FeCl^-₃₂>MgCl₂>CaCl₂>NaCl. Washing of the precipitates by either water or isotonic saline in the case of model bile and by diluted bile in the case of human bile resulted resolubilisation of a part of the phospholipids and bile salts. All these results advocated colloid chemical nature of bile. They also suggested that the micro components of the human bile give some natural protection against precipitation.

Full Text

     

K. N. Jalan ¹, M. L. Chakraborty ¹, S. K. Agarwal ¹, D. Mahalanabis ¹, D. K. Chattoraj ², S. P. Moulik ², B. S. Ahuja ³

Affiliations
1 Kothari Centre of Gastroenterology, The Calcutta Medical Research Institute, 712 Diamond Harbour Road, Calcutta-700 027, IN
2 Department of Food Technology and Bio-Engineering and Department of Chemistry Jadavpur University, Calcutta- 700 032, IN
3 Department of Chemistry, Punjab University, Patiala, IN

Abstract

Gallbladder bile from 27 control and 34 patients with cholesterol gallstone belonging to the Indian Ganges Delta have been analysed with respect to its three major components i.e. cholesterol, bile salt and phospholipid. The results when plotted on triangular co-ordinate failed to demonstrate any differences between lithogenic and non-lithogenic bile. The micellar and non-micellar boundary lines in accordance with the phase rule invoked by Admirand and Small1 and Holzbach et a1 have thus been considered ineffective as markers for patient and non-patient classification. The lithogenic index has been observed to be proportionately dependent on D/T ratio but not so on the G/T ratio. The maximum cholesterol solubility of the bile has been observed to be independent of all these parameters. The occurence of significant amounts of bile salts and phospholipids as well as calcium and iron salts alongwith cholesterol in stones suggests the inapplicability of phase rule to the stability of human bile system. The role of microcomponents of bile (ions, glycoproteins, etc.) appears to be significant for cholesterol stone formation.

Keywords

Stability of Bile, Gallstone, Phase Diagram.

Full Text

     

B. K. Roy ¹, S. P. Moulik ¹

Affiliations
1 Centre for Surface Science, Department of Chemistry, Jadavpur University, Calcutta-700 032, IN

Abstract

Interfacial and micellar properties of binary mixtures of Sodium Cholate (NaC) and Sodium Deoxycholate (NaDC) with Cetyl Pyridinium Chloride (CPC) have been investigated by surface tension and conductometric methods. The surface tension method has evidenced significantly low critical micelle concentration (CMC) whereas higher CMC values have been realised by the conductometric method. The results have been processed for estimating the maximum interfacial adsorption (Γ_max), minimum amphiphile area at the interface (A_min), free energy of adsorption (ΔG⁰_ad), free energy of micellization (ΔG⁰_m) and the fraction of counter-ion binding (p) as a function of mixture composition. Following regular solution theory of Rubingh, amphiphile composition, their interaction and activity coefficients in the mixed micelles have been estimated. Both synergism and antagonism have been observed. The amphiphile composition in the mixed micelle significantly differs from the stoichiometric composition.

Keywords

Interfacial and Micellar Properties, Sodium Cholate, Sodium Deoxycholate, Cetyl Pyridinium Chloride, Maximum Interfacial Adsorption, Free Energies of Micellization and Adsorption, Counter-Ion Binding, Regular Solution Theory.

Full Text

     

P. R. Majhi ¹, S. P. Moulik ¹, M. P. Rodgers ², S. E. Burke ², R. Palepu ²

Affiliations
1 Centre for Surface Science, Department of Chemistry, Jadavpur University, Calcutta - 700 032, IN
2 Department of Chemistry, St. Francis Xavier University, Antigonish, Nova Scotia, B2G 2W5, CA

Abstract

The interactions of SDS and AOT with PVP have been investigated by microcalorimetric, conductometric, fluorimetric and dynamic light scattering methods. The occurrence of a CAC and a CMC have been observed in microcalorimetric measurements, but were not clearly evident in the conductometric and fluorimetric experiments. From the microcalorimetric results, the energetics of CAC and CMC formation have been computed. The conductometric method has indicated two CMC points and the extent of counter ion binding to the aggregated SDS. Similar data for AOT remain inconclusive. Fluorimetric results indicating a decline in the polarity of the environment of a pyrene probe permitted the estimation of a single CMC for both SDS and AOT in PVP solution. The aggregation numbers of SDS and AOT have been found to be independent of the PVP concentration. DLS measurements have shown an increase in the hydrodynamic diameter of the polymer upon interaction with the surfactants.

Keywords

SDS, AOT, PVT Microcalorimetry, Fluorimefry, Dynamic Light Scattering.

Full Text

     

Soumen Ghosh ¹, S. P. Moulik ¹

Affiliations
1 Centre for Surface Science, Department of Chemistry, Judavpur University, Calcutta- 700 032, IN

Abstract

The clouding of binary mixtures of Triton X-100/Tween-80 and Tween-20/Brij-35 has been investigated at different compositions. The effects of ionic surfactants, SDS and CTAB on the clouding of the above binary mixtures have been also studied. The clouding of the polymers PVA and MC has been as well examined in presence of the surfactant Brij-56. The phenomenon of clouding (which is essentially a phase separation of the species in solution at a paticular temperature) has been examined in terms of solubilization process to estimate-the associated enthalpy (ΔH⁰_Cl), free energy(ΔG⁰_Cl) and entropy (ΔS⁰_Cl) values by procesing the mole fractional solubility in the light of van't Hoff type equation. The solubilisation and the energetic parameters have been attempted to rationalize and explain on physical-chemical basis.

Keywords

Cloud Points, Triton X-100/Tween-80, Tween-20/Brij-35, Brij-56/PVA, Brij-56/MC, Energetics.

Full Text