Mixing Behavior of Conventional and Gemini Cationic Surfactants

Micellization behavior of cationic monomeric surfactants, hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB), cetylpyridinium chloride (CPC), tetradecyltrimethylammonium bromide (TTAB), and dimeric (gemini) cationic surfactant pentamethylene‐1, 5‐bis(hexadecyldimethylammonium bromide) with formula C₁₆H₃₃(CH₃)₂N⁺(CH₂)₅N⁺(CH₃)₂C₁₆H₃₃ · 2Br^?, abbreviated as 16‐5‐16, in mixed states (binary) have been studied by conductivity. The micellar compositions, activities of the components, and their mutual interactions have been estimated from Rubingh's theory. The mixtures show nonideal behavior with favorable interactions.     

Synthesis of Steroidal Spiro-1′,2′,4′-triazolidine-3′-thiones

Steroidal ketone thiosemicarbazones (4–6), obtained from the corresponding ketones(1–3), on oxidative cyclization with H₂O₂ at 0°C provide title compounds (7–9), respectively. The structures of these compounds have been established on the basis of their elemental analytical and spectral data.     

Surface and micellar properties of some amphiphilic drugs in various salt solutions

In this work the effect adding of various electrolytes on the solution properties of three amphiphilic drugs was investigated. The critical micelle concentration (cmc) values, determined on the basis of surface tension measurements, were found to decrease with the increasing salt concentration; this decrease was dependent upon the nature of added ion. Coions (K⁺ and Na⁺) remained in the aqueous phase and were almost equally efficient in decreasing the cmc. Counterions (Cl^? and Br^?) concentrated on the micellar surface and reduced electrostatic repulsion. The smaller the hydrated counterions, the stronger they interacted with the micellar surface. The decrease of cmc was therefore more pronounced for Br^? ions than that for Cl^? ones. The observed changes in A _min and Γ_max were explained in terms of the cmc behavior. The values of both ΔG _m ^pO and ΔG _ads ^pO suggest that the drugs tend to form micelles more readily in the presence of salts.     

Multi-Trace Superpotentials vs. Matrix Models

We consider ᵊ9=1 supersymmetric U(N) field theories in four dimensions with adjoint chiral matter and a multi-trace tree-level superpotential. We show that the computation of the effective action as a function of the glueball superfield localizes to computing matrix integrals. Unlike the single-trace case, holomorphy and symmetries do not forbid non-planar contributions. Nevertheless, only a special subset of the planar diagrams contributes to the exact result. In addition, the computation of the superpotential localizes to doing matrix integrals. In view of the results of Dijkgraaf and Vafa for single-trace theories, one might have naively expected that these matrix integrals are related to the free energy of a multi-trace matrix model. We explain why this naive identification does not work. Rather, an auxiliary single-trace matrix model with additional singlet fields can be used to exactly compute the field theory superpotential. Along the way we also describe a general technique for computing the large-N limits of multi-trace Matrix models and raise the challenge of finding the field theories whose effective actions they may compute. Since our models can be treated as ᵊ9=1 deformations of pure ᵊ9=2 gauge theory, we show that the effective superpotential that we compute also follows from the ᵊ9=2 Seiberg-Witten solution. Finally, we observe an interesting connection between multi-trace local theories and non-local field theory.     

Role of surfactants in clouding phenomenon of imipramine hydrochloride

The clouding behavior of tricyclic antidepressant drug imipramine hydrochloride (IMP) in aqueous solution has been studied in presence of surfactants. A pH increase in the presence as well as in the absence of surfactants decreased the CP. Drug molecules become neutral at high pH and therefore head–head repulsion decreases which lead to CP decrease. Addition of non-ionic and cationic surfactants increased the CP whereas anionic surfactants showed a peaked profile. Effect of CTAB/TX-100 at different fixed drug concentrations showed that at all surfactant concentrations the CP value was higher for higher drug concentrations. However, variation of pH produced opposite effect: CP at all CTAB/TX-100 concentrations decreased with increasing pH. All results are interpreted in terms of increase in hydrophobicity or hydrophilicity of micelles on addition of surfactants.     

Synthetic strategies toward the synthesis of enoxacin-, levofloxacin-, and gatifloxacin-based compounds: A review

Enoxacin, levofloxacin, and gatifloxacin represent one of the most important prerogative scaffolds in drug development. They possess broad spectrum antimicrobial and anti-inflammatory activities. They inhibit bacterial growth by blocking their topoisomerase enzyme which is necessary for the proper functioning of bacterial DNA. In this article, we have reviewed the synthetic approaches involved in the synthesis of derivatives of enoxacin, levofloxacin, and gatifloxacin.     

Adapting Japanese Lesson Study to enhance the teaching and learning of geometry and spatial reasoning in early years classrooms: a case study

Increased efforts are needed to meet the demand for high quality mathematics in early years classrooms. Despite the foundational role of geometry and spatial reasoning for later mathematics success, the strand receives inadequate instructional time and is limited to concepts of static geometry. Moreover, early years teachers typically lack both content knowledge and confidence in teaching geometry and spatial reasoning. We describe our attempt to deal with these issues through a research initiative known as the Math for Young Children project. The project integrates effective features of both design research and Japanese Lesson Study and is designed to support teachers in developing content knowledge and new approaches for teaching geometry and spatial reasoning. Central to our Professional Development model is the integration of four adaptations to the Japanese Lesson Study model: (1) teachers engaging in the mathematics, (2) teachers designing and conducting task-based clinical interviews, (3) teachers and researchers co-designing and carrying out exploratory lessons and activities, and (4) the creation of resources for other educators. We present our methods and the results of our adaptations through a case study of one Professional Learning Team. Our results suggest that the adaptations were effective in: (1) supporting teachers’ content knowledge of and comfort level with geometry and spatial reasoning, (2) increasing teachers’ perceptions of young children’s mathematical competencies, (3) increasing teachers’ awareness and commitment for the inclusion of high quality geometry and spatial reasoning as a critical component of early years mathematics, and (4) the creation of innovative resources for other educators. We conclude with theoretical considerations and implications of our results.     

Neutron and gamma ray doses from a 252Cf brachytherapy source in a water phantom

Axial and radial doses of Neutrons and gamma rays from an Isotron ²⁵²Cf Brachytherapy source were calculated in a Water phantom using Maienshein’s prompt fission gamma rays data and Maxwellian neutron energy spectrum. It was observed that neutron dose due to the source casing thickness does not contribute significantly to the total dose. Further the calculated secondary gamma ray dose rate is very small compared to the calculated primary gamma dose rate. Neutron and secondary gamma ray dose calculated in this study agree with the published data. Results of this study will be presented here.