An Improved Heuristic for the Quadratic Assignment Problem

A technique is described whereby the computational efficiency of the Lashkari-Jaisingh heuristic for the quadratic assignment problem is greatly enhanced. Results for the modified heuristic are presented which demonstrate that it provides solutions of consistently high quality at relatively small computational cost.     

Target excitations and the optical potential for protons scattering from nuclei

We calculate the contributions to the optical potential for 30 MeV protons due to inelastic excitations of the target nucleus. The scattering due to this non-local potential is calculated exactly and some of the results subjected to conventional optical model analysis. When only one excited state is included, a resonant dependence on the excitation energy is observed. Even with ten excited states, the position of a single one can strongly influence the scattering. It is possible to account for about $\text{3}\text{4}$ of the observed absorption in ⁴⁰Ca and ²⁰⁸Pb, but only by postulating unobserved states which exhaust the remainder of the experimental sum rules at somewhat unreasonably low energies. It was not possible to find simple local potentials which gave the same scattering because of the strong L-dependence of the absorption. The constructed potentials concentrate the absorption at too small radii. It is suggested that rearrangement (pick-up) processes contribute a substantial amount of absorption at larger radii, while compound formation will give rise to a volume term in the imaginary potential.     

New Lyotropic nematic phases with unusual anisotropies of magnetic susceptibility: Type I DM and type II CM

Two lyotropic mesophases of opposite signs of susceptibility anisotropy have been found, one a quaternary and the other a ternary phase. Conclusive evidence is presented that the disk-micelle mesophase has positive diamagnetic anisotropy and the rod-like micelle phase has negative anisotropy. These have been named type I DM and type II CM mesophases respectively to conform with the notation previously introduced for mesophases based on aliphatic chain surfactants.     

Proton Spin Relaxation in the Rod Micelles of Type I CM Mesophases

The dynamics of the hydrocarbon chains in lyotropic nematic type I cylindrical micellar liquid crystals prepared with D₂O has been selectively studied by Zeeman and rotating frame nuclear spin-lattice relaxation. The measurements of the proton spin-lattice relaxation time T ₁ as a function of frequency and temperature demonstrate that relatively fast local fluctuations of individual amphiphilic chains relax the proton spins at high magnetic fields. This process is facilitated also by the rapid diffusive motion of the chains within the micellar units. The rotating frame Zeeman relaxation time T _1x, is associated at room temperature with a long correlation time of ~11 μs. Slow micellar orientational fluctuations have been assigned to this characteristic time.     

Interface Anchoring of p-alkyl Phenols in Disc-micelles of Mesophases

Five para-alkyl substituted phenols have been studied as solutes in two chemically different type II DM mesophases. The degrees of order for the aromatic ring, are not significantly affected by the different short alkyl chains, showing that the anchoring of the -OH group at the aqueous interface is the dominant determinant of local motion. The principal change in the diagonal degrees of order between the chemically different mesophases resides in the change in size of disc micelles with consequent changes in their motional freedom. The anchoring of the phenol -OH at the aqueous interface shows little or no perturbation from the chemical variation of neighboring amphiphiles in the micelle bilayer.     

Anthocyanins and their variation in red wines I. Monomeric anthocyanins and their color expression

Originating in the grapes, monomeric anthocyanins in young red wines contribute the majority of color and the supposed beneficial health effects related to their consumption, and as such they are recognized as one of the most important groups of phenolic metabolites in red wines. In recent years, our increasing knowledge of the chemical complexity of the monomeric anthocyanins, their stability, together with the phenomena such as self-association and copigmentation that can stabilize and enhance their color has helped to explain their color representation in red wine making and aging. A series of new enological practices were developed to improve the anthocyanin extraction, as well as their color expression and maintenance. This paper summarizes the most recent advances in the studies of the monomeric anthocyanins in red wines, emphasizing their origin, occurrence, color enhancing effects, their degradation and the effect of various enological practices on them.