Mixed micellization and interfacial properties of dodecyltrimethylammonium bromide and tetraethyleneglycol mono-n-dodecyl ether in absence and presence of sodium propionate

Mixed micelle formation and interfacial properties of aqueous binary surfactant combinations of dodecyltrimethylammonium bromide (C12TAB) and tetraethyleneglycol mono-n-dodecyl ether (C12E4) at 30 degrees C in absence and presence of sodium propionate (NaPr) have been investigated. The critical micelle concentration, aggregation number, micropolarity and interfacial adsorption have been quantitatively estimated by surface tension and steady-state fluorescence measurements. The micellar and adsorption characteristics like composition, activity coefficients and mutual interaction parameters have been estimated following different theoretical treatments like that of Clint, Rubingh, Rodenas, Maeda, Blankschtein and Rosen. The analysis reveals very small mole fraction of cationic surfactant in both the mixed micelles and mixed monolayer inspite of synergism. Blankschtein's model predicts a continuous decrease in synergism due to the salt effect of NaPr; Rubingh's approach, on the contrary, indicates an increase in it above 30 mM of NaPr concentration. Aggregation number variation with NaPr indicates the same. Mixed monolayer shows better synergism compared to that in mixed micelles which increases with the addition of sodium propionate above 30 mM concentration.     

A subdivision collocation method for solving two point boundary value problems of order three

In this paper, we propose a method for the numerical solution of self adjoint singularly perturbed third order boundary value problems in which the highest order derivative is multiplied by a small parameter $\varepsilon$. In this method, first we introduce the derivatives of two scale relations satisfied by the subdivision schemes. After that we use these derivatives to construct the subdivision collocation method for the numerical solution of singularly perturbed boundary value problems. Convergence of the subdivision collocation method is also discussed. Numerical examples are presented to illustrate the proposed method.     

A synthesis of the γ-secretase inhibitor BMS-708163

A concise, convergent racemic synthesis of BMS-708163 is reported. Two fragments consisting of N-4-chlorophenylsulfonyl-3,3,3-trifluorpropylglycine and a 1,2,4-oxadiazole derivative of 2-fluorobenzyl alcohol were prepared in separate pots and then coupled together via a Mitsunobu reaction. Since a convenient chiral synthesis of optically pure (d)-3,3,3-trifluoropropyl glycine methyl ester was developed using Schöllkopf reagent alkylation, this methodology can also be adopted for the enantioselective synthesis of BMS-708163.     

A Note on Classification of Teleparallel Conformal Vector Fields in Cylindrically Symmetric Static Space-Times in the Teleparallel Theory of Gravitation

In this paper we explored teleparallel conformal vector fields in cylindrically symmetric static space-times in the teleparallel theory of gravitation by using the direct integration technique. It turns out that the dimension of teleparallel conformal vector fields are 8, 9, 10 or 11. The case VI in which the space-time becomes conformally flat admits eleven independent teleparallel conformal vector fields.     

Alpha-glucosidase inhibitory constituents from Cuscuta reflexa

Two new compounds, 7'-(3',4'-dihydroxyphenyl)-N-[(4-methoxyphenyl)ethyl]propenamide (4), and 7'-(4'-hydroxy,3'-methoxyphenyl)-N-[(4-butylphenyl)ethyl]propenamide (5) have been isolated from Cuscuta reflexa along with five known compounds, 6,7-dimethoxy-2H-1-benzopyran-2-one (1), 3-(3,4-dihydroxyphenyl)-2-propen-1-ethanoate (2), 6,7,8-trimethoxy-2H-1-benzopyran-2-one (3), 3-(4-O-beta-D-glucopyranoside-3,5-dimethoxyphenyl)-2-propen-1-ol (6), 2-(3-hydroxy-4-methoxyphenyl)-3,5-dihydroxy-7-O-beta-D-glucopyranoside-4H-1-benzopyrane-4-one (7), reported for the first time from this species. Structures of these compounds were determined by spectral analysis. These compounds showed strong inhibitory activity against alpha-glucosidase.     

Synthesis and anti-inflammatory activity of fluorinated isocoumarins and 3,4-dihydroisocoumarins

The synthesis of several fluorinated isocoumarins and 3,4-dihydroisocoumarins are described. The structures of the synthesized compounds were confirmed by spectral and elemental analysis. All synthesized compounds were evaluated for their anti-inflammatory and antioxidant activity. These compounds were found to present antioxidant and anti-inflammatory activities. A few of them were found to be significantly active in vivo against ear edema in mice produced by 12-O-tetradecanoylphorbol-13-acetate (TPA) and also good radical scavengers.     

Clouding behavior of nonionic–cationic and nonionic–anionic mixed surfactant systems in presence of carboxylic acids and their sodium salts

The study is focused on evaluation of clouding phenomena of the aqueous single nonionic surfactant system Triton X-100 (TX-100) and its mixed systems with anionic aerosol-OT (AOT) and cationic dodecylpyridinium chloride (DPC) in presence of hydrophobic ions furnished by sodium salts of carboxylic acids, viz., sodium ethanoate, sodium propanoate, sodium butanoate, and sodium hexanoate and the respective carboxylic acids [ethanoic acid, propanoic acid, butanoic acid, and hexanoic acid]. The influence of salts on the cloud point (CP) has been explained on the basis of salt effect as well as the solubilization of higher alkyl chain hydrophobic ions furnished by these salts. Moreover, the co- and counterion effect has been taken into account to explain the variation of the CP in the mixed systems. However, the effect of acids on CP has been explained in the light of their aqueous solubility and their partitioning ability between octanol and water as reflected by their K _OW values.     

Microbial transformation of dehydroepiandrosterone

Transformation of dehydroepiandrosterone (DHEA) (1) was carried out by a plant pathogen Rhizopus stolonifer, which resulted in the production of seven metabolites. These metabolites were identified as 3beta,17beta-dihydroxyanandrost-5-ene (2), 3beta,17beta-dihydroxyandrost-4ene (3), 17beta-hydroxyandrost-4-ene-3-one (4), 3beta,11-dihydroxyandrost-4-ene-17-one (5), 3beta,7alpha-dihydroandrost-5-ene-17-one (6), 3A,7alpha,17beta-trihydroxyandrost-5-ene (7) and 11beta-hydroxyandrost-4,6-diene-3,17-dione (8). The structures of the transformed products were determined by the spectroscopic techniques.     

Problem-independent nonlinear switch for newly designed WENO-BO-Z scheme

The uniformly third-order WENO-BO-Z scheme has been proposed previously in an attempt to restore third-order accuracy at the second-order critical point via the reduction of nonlinear dissipation followed by the modification of nonlinear weights as well as to improve the intermediate bandwidth property of the linear optimal stencil of the classical WENO-JS scheme with respect to both dispersion and dissipation. However, a problem-dependent nonlinear switch was employed to turn on in the intermediate range of wavenumbers to avoid unnecessary nonlinear adaption of the WENO scheme and was mainly dependent on the trial-and-error threshold value of a switch parameter. In order to avoid the problem-dependent nature of this switch, a problem-independent nonlinear switch is suggested and investigated in this work. Benchmark problems, ranging from non-broadband to broadband, are solved using the WENO-BO-Z scheme, and a comparison of the suggested switch with the problem-dependent switch is made.