D. Liu and X. Zhu,Erratum to: “Fractional chromatic number and circular chromatic number for distance graphs with large clique size”. Journal of Graph Theory47(2) 2004, 129–146

The original article to which this Erratum refers was published in Journal of Graph Theory 47:129–146,2004 .     

Trimeric liquid crystals containing lateral alkyl chains

The first twelve members of the n-alkyl 2,5-bis-(4'-cyanobiphenyloxybutyloxy)-benozates have been prepared. The compounds are nematogenic; in addition the first three members exhibit a smectic A phase. The nematic-isotropic transition temperatures decrease with little or no alternation on increasing the number of methylene groups in the lateral chain; this is analogous to the behaviour found in monomeric and polymeric mesogens possessing lateral alkyl chains.     

SPECTRAL PROPERTIES,PHOTOTRANSFORMATION KINETICS AND PELLETABILITY OF PHYTOCHROME IN Pharbitis nil Chois*

Abstract— An examination has been made of the involvement of phytochrome in the circadian rhythm of flowering in Pharbitis nil Chois. The peak position of P_fr absorption changes with time after a red light pulse. The shortest absorption wavelength of P_fr occurs at the same time as flowering is inhibited by red light in dark grown, red light pretreated plants. Pelletable and supernatant phytochrome show a similar trend with lowest values found at the time of flower inhibition. Neither phototransformation kinetics nor intermediates of phytochrome which accumulate in white light show such a relationship to the circadian rhythm found in flowering of dark grown P. nil.     

Surface tension of a Lennard-Jones liquid under supersaturation

A formally exact Kirkwood-Buff virial formula for the surface tension of a supersaturated interface is derived. A modified Gibbs ensemble method is given that allows the creation of interacting supersaturated phases of equal chemical potential, and which enables the Kirkwood-Buff formula to be applied. The methods are tested by Monte Carlo simulation of a supersaturated Lennard-Jones fluid with a planar liquid-vapor interface. The Kirkwood-Buff results for the supersaturated surface tension are found to be in reasonable agreement with new results obtained here using the recently developed, formally exact, ghost interface method, [M. P. Moody and P. Attard, J. Chem. Phys., 2002, 117, 6705]. The surface tension is obtained as a function of supersaturation at four temperatures, and it is found to decrease with increasing supersaturation, and to vanish at the vapor spinodal. The relevance of the present results to the nucleation of droplets in a supersaturated vapor is discussed.     

Amphitropic liquid crystals. Two lamellar phases in a surfactant containing thermotropic and lyotropic mesogenic groups

Abstract

We have studied the lyotropic liquid-crystalline behaviour of cationic surfactants containing a potentially thermotropic moiety, a terminal cyanobiphenyloxy group. Both mono-alkyl and mid-chain substituted dialkyl surfactants have been examined using optical microscopy and NMR spectroscopy. Incorporation of the cyanobiphenyloxy group destabilizes the hexagonal and bicontinuous cubic phases, with only an extensive lamellar region being observed. For the dialkyl surfactant there is a range of compositions where two lamellar phases co-exist, one water-rich and the second surfactant-rich.     

Copper Bis(oxazoline)-Catalyzed Enantioselective Alkynylation of Benzopyrylium Ions

The stereocontrolled construction of biologically relevant chromanones and tetrahydroxanthones has been achieved through the addition of alkynes to benzopyrylium trilfates under the influence of copper bis(oxazoline) catalysis. Excellent levels of enantiocontrol (63–98 % ee) are achieved in the addition of a variety of alkynes to an array of chromenones with a hydrogen in the 2-position. Promising levels of enantiocontrol (54–67 % ee) are achieved in the alkynylation of chromenones with esters in the 2-position, generating tertiary ether stereocenters resembling those frequently found in naturally occurring metabolites.     

Pretransitional behaviour in nematic liquid crystals

A simple (four sites on the water molecule) potential for Cl^-/H₂O has been generated from six gradient calculations. The potential is in reasonable agreement with the extensive SCF calculations of Dacre.     

The Effect of Molecular Weight on the Thermal Properties of Polystyrene-Based Sidechain Liquid-Crystalline Polymers

Abstract

Sidechain liquid-crystalline polymers were prepared by the derivatization of three poly(4-hydroxystyrene) fractions of different molecular weights (M_w = 1.0 × 10⁴, 2.2 × 10⁴ and 3.0 × 10⁴). 4-Cyanoazobenzene and 4-cyanobiphenyl were incorporated as mesogenic groups with ether-linked methylene spacers of varying length. The polymers all exhibited a smectic A phase, with the exception of the propyl member of the cyanobiphenyl series for which no liquid-crystalline behavior was observed. For short spacers the thermal properties were insensitive to molecular weight changes in the backbone, whereas small but consistent differences in the transition temperatures and entropies were observed as the number of methylene groups in the spacer increased.     

Metastable Ionic Diodes Derived from an Amine‐Based Polymer of Intrinsic Microporosity

A highly rigid amine‐based polymer of intrinsic microporosity (PIM), prepared by a polymerization reaction involving the formation of Tröger’s base, is demonstrated to act as an ionic diode with electrolyte‐dependent bistable switchable states.