Theory of interfacial phase transitions in surfactant systems

The spin-1 Ising model, which is equivalent to the three-component lattice gas model, is used to study wetting transitions in three-component surfactant systems consisting of an oil, water, and a nonionic surfactant. Phase equilibria, interfacial profiles, and interfacial tensions for three-phase equilibrium are determined in mean field approximation, for a wide range of temperature and interaction parameters. Surfactant interaction parameters are found to strongly influence interfacial tensions, reducing them in some cases to ultralow values. Interfacial tensions are used to determine whether the middle phase, rich in surfactant, wets or does not wet the interface between the oil-rich and water-rich phases. By varying temperature and interaction parameters, a wetting transition is located and found to be of the first order. Comparison is made with recent experimental results on wetting transitions in ternary surfactant systems.This paper is dedicated to J. K. Percus in honor of his 65th birthday.     

Stereospecific solid-state NaBH4-promoted reduction of 1-methylpentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione

NaBH₄ reduction of a cage dione proceeds in a stereospecific fashion to give theendo,endo-diol. This reactivity is related to the crystal structure.     

Working group report: Flavor physics and model building

This is the report of flavor physics and model building working group at WHEPP-9. While activites in flavor physics have been mainly focused on B-physics, those in model building have been primarily devoted to neutrino physics. We present summary of working group discussions carried out during the workshop in the above fields, and also briefly review the progress made in some projects subsequently.     

ENSTAR detector forη- mesic studies

We have initiated a search for a new type of nuclear matter, theη-mesic nucleus, using beams from the multi-GeV hadron facility, COSY at Juelich, Germany. A large acceptance scintillator detector, ENSTAR has been designed and built at BARC, Mumbai and fully assembled and tested at COSY. A test run for calibration and evaluation has been completed. In this contribution we present the design and technical details of the ENSTAR detector and how it will be used to detect protons and pions (the decay products ofη-mesic bound state). The detector is made of plastic scintillators arranged in three concentric cylindrical layers. The readout of the detectors is by means of optical fibres. The layers are used to generate ΔE –E spectra for particle identification and total energy information of stopped particles. The granularity of the detector allows for position (θ and ?ø determination making the event reconstruction kinematically complete     

Kinetics of the oxidation of oxalic acid by cerium(IV) sulfate in dilute sulfuric acid

The kinetics of the oxidation of oxalic acid by cerium(IV) in sulfuric acid medium has been studied voltammetrically. The specific reaction rate is 132±4.0 M^–1s^–1 at 25.0 °C. The energy of activation is 62.6±3.0 kJ mol^–1. The entropy of activation is –2.7 J mol^–1K^–1. The specific reaction rate is influenced by complexation and also by ionic strength (). The most likely mechanism has been suggested.

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(IV) . 132±4,0 M^–1c^–1 25,0 °C. 62,6±3,0 ·M^–1. –2,7 ·K^–1M^–1. , (). .

     

Substituted m-phenylene bridges as strong ferromagnetic couplers for Cu(II)-bridge-Cu(II) magnetic interactions: new perspectives

Based on a combined theoretical-experimental study, we propose that substituted m-phenylene ligands (m-N-Phi-N) can act as tuneable strong ferromagnetic couplers connecting Cu(II) ions; a new complex presenting that bridge with J close to +15 cm(-1) has been suggested and synthesized.     

Studies on the extraction behaviour of plutonium(IV) from mixed aqueous-organic media with sulphoxides

Extraction behaviour of plutonium (IV) from nitric acid media by two long-chain aliphatic sulphoxides, namely, di-n-hexylsulphoxide and di-n-octylsulphoxide has been investigated in the presence of several water-miscible organic solvents to study their possible synergistic effect on metal ion extraction. Methanol, ethanol, n-and iso-propanol, dioxane, acetone as well as as acetonitrile were used as the organic component of the mixed (polar) phase. These additives affected the extraction to varying degrees. Thus, extractability of Pu increases 2–3 fold with increasing concentration (upto 20%) of acetonitrile, acetone, methanol and ethanol while it decreases with increasing concentration of n-and isopropanol. At high concentration of the former, synergism changes into antagonism. Possible reasons for such behaviour are briefly discussed. Among these organic additives, maximum enhancement in the extraction of Pu(IV) was observed in the presence of acetonitrile. The relative increase in extraction was found to be more at lower sulphoxide concentrations.     

Facilitated phosphatidylserine flip-flop across vesicle and cell membranes using urea-derived synthetic translocases

Tris(2-aminoethyl)amine derivatives with appended urea and sulfonamide groups are shown to facilitate the translocation of fluorescent phospholipid probes and endogenous phosphatidylserine across vesicle and erythrocyte cell membranes. The synthetic translocases appear to operate by binding to the phospholipid head groups and forming lipophilic supramolecular complexes which diffuse through the non-polar interior of the bilayer membrane.