Tungsten resistant (Wr) mutants of Het+Nif+Nia+, Het+Nif-Nia+ and Het+Nif+Nia- strains of Nostoc muscorum were isolated with severely defective molybdate transport activity. All such mutants showed vanadium (V)-dependent nitrogenase activity and/or nitrate reductase activity and V-dependent growth on N2-nitrogen and/or NO3(-)-nitrogen and V-dependent NO3(-)-repression of heterocyst formation and nitrogenase activity. None of them grew with molybdenum (Mo) under parallel growth condition. Results strongly suggest the ability of V to replace Mo in N2-assimilation or NO3(-)-assimilation under Mo-deficiency.

Single solubilization of Sudan IV and anthracene has been studied in aqueous surfactant systems of sodium dodecyl sulphate, cetyltrimethylammonium bromide and Triton X-100 at 30°C by a spectrophotometric technique. Sudan IV was found to be more highly solubilized in micellar solutions than anthracene. Solubilization of Sudan IV and anthracene in the presence of each other was also studied in the surfactant systems. It was found that Sudan IV is preferentially solubilized over anthracene when solubilized jointly. This is reflected in the calculated values of the number of moles of surfactant solubilizing 1 mol of dye, the free energy change and the number of molecules of dye solubilized in a micelle. From the successive solubilization studies of Sudan IV and anthracene it has been found that the absorbance of one solubilizate does not change after the addition of the second solubilizate. The solubilization behaviour of dyes was discussed with respect to the aggregation number, occupancy of different solubilization sites and the chemical nature of the two dyes.

The effect of n-amines on sphere-to-rod transitions in aqueous micella, solutions of cationic and anionic surfactants was studied by viscosity measurements at various temperatures. The surfactants studied were cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). It was observed that the relative viscosities of concentrated micellar solutions increased abruptly above a certain amine concentration depending upon the nature of the amine. The effect of amines on the activation energy for viscous flow was studied from the temperature dependence of viscosity. A large increase in viscosity and activation energy by the addition of amine has been attributed to the change in the shape of micelles from sphere to rod or sphere to disc-like. The effect of amines on the viscosity and activation energy of anionic micelles was tremendously large as compared to cationic micelles. Charge induced solubilization of amines was responsible for the higher viscosity and activation energy for viscous flow of the SDS micellar solution.

The effect of addition of n-alcohols on the viscosity of cetyltrimethylammonium bromide (CTAB) micellar solution in the presence of KBr at various temperatures is presented. Lower alcohols (C2 and C3) were found to decrease the viscosity of CTAB solution in the presence of KBr right from the beginning. The viscosities of micellar solutions were found to increase on the addition of 1-butanol, 1-pentanol and 1-hexanol in low concentrations. Depending on the nature of the alcohol, further addition of these alcohols either made the solution turbid or lowered the viscosity of the solutions. The thermodynamic parameters for the viscous flow of micellar solutions in the presence of alcohols have been determined. The results are interpreted in terms of the possible transition of micellar shape from rod to sphere or to elongated rods in the presence of added alcohols.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInteraction of ionic micelles with the hydrophobic fluorescent probe 1-anilino-8-naphthalenesulfonateK. S. Birdi, H. N. Singh, and S. U. DalsagerCite this: J. Phys. Chem. 1979, 83, 21, 2733–2737Publication Date (Print):October 1, 1979Publication History Published online1 May 2002Published inissue 1 October 1979https://pubs.acs.org/doi/10.1021/j100484a010https://doi.org/10.1021/j100484a010research-articleACS PublicationsRequest reuse permissionsArticle Views252Altmetric-Citations56LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts