Particle tunneling and scattering in a three-dimensional potential with a barrier

The particle tunneling through a 3-D rectangular potential barrier has been studied. The simplest model for multiple internal reflections has been assumed. The explicit expression for all the transmission and reflection probability amplitudes have been derived, as well as the tunneling and reflection phase times.      

Folding of aromatic oligoimides of trans-1,2-diaminocyclohexane

Chiral oligomeric diimides prepared from pyromellitic dianhydride, (R,R)-1,2-diaminocyclohexane and phthalic anhydride fold into M or P helical conformers; trimer 1 folds into the P conformer in the crystal but the M conformer dominates in solution; longer chain oligomers 2 and 3 form preferentially P conformers in solution, as a result of intermolecular interactions.     

Beyond Flory-Huggins theory: new classes of blend miscibility associated with monomer structural asymmetry

Flory-Huggins (FH) theory is restricted to polymer mixtures whose monomers are structurally identical, a situation limited to isotopic blends and computer simulations. We investigate the influence of monomer structure on blend miscibility and scattering properties using the lattice cluster theory generalization of the FH model. Monomer structural asymmetry is shown to profoundly affect blend miscibility (T(c),phi(c)), chain swelling (T(theta)), and the scale (xi) and intensity [S(0)] of composition fluctuations. Four distinct blend miscibility classes are identified and experimental evidence for these classes is discussed.     

Transport Coefficients in Some Stochastic Models of the Revised Enskog Equation

A stochastic model of the revised Enskog equation is considered. A choice of the smearing function suggested by the work of Leegwater is used to apply the model to the repulsive part of the Lennard-Jones potential and the inverse-power soft-sphere potential. The virial coefficients obtained from the equilibrium properties of the models are in excellent agreement with the known exact coefficients for these models. The transport coefficients for the repulsive Lennard-Jones (RLP) model are also computed and appear to be of comparable accuracy to the Enskog-theory coefficients applied directly to a hard-sphere system, although exact results for the RLP with which to make an extensive comparison are not yet available. The pressure and the transport coefficients obtained from the model (shear viscosity, thermal conductivity, and self-diffusion) are compared with the pressure and the corresponding transport coefficients predicted by the Enskog and square-well kinetic theories.     

Symmetries of Cauchy-Riemann spaces

We simplify and generalize Cartan's results on Cauchy-Riemann spaces admitting continuous groups of automorphisms. We describe all such spaces in terms of local coordinates.     

Photochemical synthesis of 7H-indolo[1,2-a]quinolinium salts - a new ring system

Photodehydrocyclization of 1-phenyl-2-/2-arylethenyl/-3,3-dialkyl-3H-indolium cations leads in very good yield to 7H-indolo[1,2-a]quinolinium cations.