A simple efficient sequential one-pot intermolecular aza-Michael addition and intramolecular Buchwald–Hartwig α-arylation of amines: synthesis of functionalized tetrahydroisoquinolines

An efficient one-pot sequential intermolecular aza-Michael addition and Pd-catalyzed intramolecular Buchwald–Hartwig α-arylation of secondary amines have been investigated, for the synthesis of tetrahydroisoquinolines. This method is simple and furnished products in very good yield and also successfully applied for the synthesis of novel aza-spirotricylcic ethers.     

Gallium(III)-catalyzed tandem cycloisomerization/Friedel–Crafts alkylation: a facile synthesis of 2,5-disubstituted furans

A tandem cycloisomerization/Friedel–Crafts alkylation of indoles has been achieved in a one-pot process to produce 2,5-disubstituted furans using gallium-catalyzed sequential nucleophilic addition onto metal-activated 1-alkynyl-2,3-epoxy acetates. The reaction proceeds efficiently under mild conditions with complete regioselectivity to afford the substituted furan derivatives in good yields with high diversity.     

Instabilities in free-surface electroosmotic flows

Instability of a thin electrolyte film undergoing a direct current electroosmotic flow has been investigated. The film with a compliant electrolyte–air interface is flowing over a rigid charged substrate. Unlike previous studies, inclusion of the Maxwell stresses in the formulation shows the presence of a new finite wavenumber shear-flow mode of instability, alongside the more frequently observed long-wave interfacial mode. The shear mode is found to be the dominant mode of instability when the electrolyte–solid and electrolyte–air interfaces are of opposite charge or of same charge but have very large zeta-potential at the electrolyte–air interface. The conditions for mode-switch (interfacial to shear) and the direction of the travelling waves are discussed through stability diagrams. Interestingly, the analysis shows that when the interfaces are of nearly same zeta potential, the ‘free’ electrolyte–air interface behaves more like a ‘stationary’ wall because of the ion transport in the reverse direction of the flow.     

Anomalous elastic behaviour of Bi-Pb-Ag composites

Bi-Pb and Bi-Pb-Ag superconducting composites have been prepared by the solid state reaction method. After the usual characterization, ultrasonic longitudinal velocity and attenuation studies have been undertaken over a temperature range 80–300 K by the pulse transmission technique. In contrast to normal solids, the ultrasonic velocities of both the samples in the temperature range 200-100 K are found to decrease with decreasing temperature (softening), followed by a velocity maximum. The samples are also found to exhibit longitudinal attenuation peaks at TEMPERATURES = 260, 160 and 120 K. An attempt has also been made to verify whether the Wachtman's equations can theoretically explain the low-temperature behaviour of the Young's modulus of these materials. A qualitative explanation for both the phenomena of softening of velocity as well as the occurrence of attenuation peaks is given.     

Electronegativities in the calculation of diatomic molecular parameters (Hydrides of some transition elements)

The force constants for diatomic molecules and isolated bonds may be expressed by using equalized electro-negativities, bond orders, bond strengths and interatomicdistances. We have studied Mn¹H, Mn²H, Co²H, Ni¹H, Ni²H, Cu¹H, Cu²H, Ag¹H, and Ag²H and have determined the proportionality constant d, as well as the Lennard-Jones parameters a and b, for the potential energy functions used by Szöke and calculated the anharmonicity ω_eξ_e and the rotational-vibrational coupling constant α_e. The relation between electronegativity and ionization potential has been verified and the variations of molecular parameters with atomic number Z have been studied.     

On Totally Ordered Rings Whose Positive Cones are Finitely Generated

This paper is mainly dealt with the structure of totally ordered rings (t.o. rings) whose positive cones are finitely generated as multiplicative right ideals.AMS Subject Classification (1991): 16W80, 13J25     

Preparation and electrical characterization of (PVC + KBrO3) polymer electrolytes for solid state battery applications

This paper presents results of studies on dc electrical conductivity and transference number measurements on potassium bromate (KBrO₃) complexed polyvinyl chloride (PVC) films prepared by solution cast technique. Temperature dependence of dc electrical conductivity and transference number data indicated the dominance of ion type charge transport in these specimens. The magnitude of conductivity increased with increase in concentration of the salt and temperature. Using this (PVC + KBrO₃) electrolyte, solid-state electrochemical cells were fabricated, and their discharge profiles were studied under a constant load of 100 kΩ. Several cell profiles such as open circuit voltage, short circuit current, power density, and energy density associated with these cells were evaluated and were reported. The features of complexation of the electrolytes were studied by X-ray diffraction and Fourier transform infrared spectroscopy. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006     

Magnetic-field-induced valence transition in rare-earth systems

The magnetic-field-induced valence transition in rare-earth systems has been investigated using the periodic Anderson model supplemented by the Falicov-Kimball term. This model has been solved by first decoupling the Falicov-Kimball term as proposed by Khomskii and Koharjan and then taking the limit of infinite intra-site Coulomb repulsion. The valence transition both in the absence and in the presence of magnetic field as a function of temperature is studied. It has been found that the system makes transition from non-magnetic to magnetic state when the magnetic field increases beyond a critical value H _c. The phase boundary defined in terms of reduced field H _c(T)/H _c(0) and reduced temperature T/T _v (T _v being the valence transition temperature in the absence of field) is almost independent of the position of the localized level. The results are in qualitative agreement with experimental observations in Yb- and Eu-compounds.