Columnar liquid crystals in oligosaccharide derivatives. II. Two types of discotic columnar liquid-crystalline phase of cellobiose alkanoates

A series of cellobiose octaalkanoates, Cel-II-n (n is the carbon number of the alkyl chain), with n = 7-14 were prepared and their mesogenic properties examined by differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction. All of these compounds form enantiotropic discotic columnar phases, in which the columns are built up by a regular stacking of the cellobiose moieties and are packed in a two dimensional lattice. Homologues with n = 9-14 form the D_ho phase only whilst the compound with n = 7 forms the D_ro phase. The n = 8 compound forms the D_ho phase at higher temperatures and the D_ro phase at lower temperatures. Structural parameters obtained from X-ray diffraction studies are presented for both phases.     

INDO Studies on the structure of benzosemiquinone radicals

The spin densities of the radical anions from 4-methylcatechol, 4-carboxylic catechol, and 3-methylcatechol were calculated by means of the INDO method with the geometrical parameter adjusting method. The observed protion hyperfine coupling constants were exactly reproduced.     

Exactly solvable models showing chaotic behavior

Several examples of the one-dimensional mapping which are exactly solvable and show chaotic behaviour are presented. The importance of the accuracy of the numerical calculation is stressed.     

Thermosensitive copolymers having soluble and insoluble monomer units,poly(N‐vinylacetamide‐co‐methyl acrylate)s: Effect of additives on their lower critical solution temperatures

New thermosensitive polymers were synthesized by copolymerization between N‐vinylacetamide (NVA) and methyl acrylate whose homopolymers are soluble and insoluble in water, respectively. The lower critical solution temperature (LCST) of the obtained copolymers ranged between 59 and 83 °C, and the LCST increased with an increasing NVA content in the copolymers. The effectiveness of various salts addition on lowering the LCST of the copolymer solutions followed Hoffmeister series. NaCl and Na₂SO₄ addition linearly lowered the LCST with an increasing salts concentration, and slopes of the lines were almost constant regardless of the copolymer composition. The effectiveness of alcohols with various alkyl chain lengths on lowering the LCST did not follow the viscosity B coefficient values of the alcohols, which was probably the result of preferential adsorption of the alcohols to the copolymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2651–2658, 2004     

Einzelschichten und Mehrfachschichten von Anthrachinonderivaten mit langen Alkylketten

Ohne Zusammenfassung     

String-like phase in Yang-Mills theory

A dynamical mechanism is discussed leading to the phase where the string of the color flux tube is formed in Yang-Mills theory. The pairing force between massless gauge fields in the color single channel forms a tachyon or a Cooper state and leads to the instability of the normal vacuum. A stable vacuum is required to remain massless after the condensation of pairs. Then the stability of the new vacuum leads to the condition on the 't Hooft index α which is equivalent to the condition of the existence of the string solutions.