Generation of a chiral mesophase by achiral molecules: absolute chiral induction in the smectic C phase of 4-octyloxyphenyl 4-octyloxybenzoate

Achiral rodlike molecules possessing an ester group generated a chiral smectic liquid crystal phase.     

Blocks of central -group extensions

Let and be finite groups that have a common central -subgroup for a prime number , and let and respectively be -blocks of and induced by -blocks and respectively of and , both of which have the same defect group. We prove that if and are Morita equivalent via a certain special -bimodule, then such a Morita equivalence lifts to a Morita equivalence between and .

     

Martin boundary of unlimited covering surfaces

LetW be an open Riemann surface and ap-sheeted (1<p<∞) unlimited covering surface ofW. Denote by Δ¹ (resp., ) the minimal Martin boundary ofW (resp., ). For ζ ∈ Δ, let ζ be the (cardinal) number of the set of pionts which lie over ζ and the class of open connected subsetsM ofW such thatM∪{ζ} is a minimal fine neighborhood of ζ. Our main result is the following: , where is the number of components of π^-1 M and π is the projection of ontoW. Moreover, some applications of the above results are discussed whenW is the unit disc.     

The Effect of Solvent on Competing Hydroperoxide and Dioxetane Formation on Photo-Sensitized Oxygenation of Olefins

The rates of the competitive photo-sensitized oxygenation of 2-isobutylideneadamantane ( 1 ) and 2-propylidene-adamantane ( 2 ) with 1, 1-di-t-butyl-2-methoxyethane ( 3 ) in various solvents were determined. The rates for 1 and 2 were independent of solvent, whereas that for 3 varied markedly with solvent polarity. Compounds 1 and 2 gave only hydroperoxides while 3 gave dioxetane. These results are interpreted in terms of two competing processes involving little and much charge separation leading to hydroperoxide and dioxetane, respectively.     

Measurements of exciton absorption with pico-second light pulses produced by a self-phase modulation technique

Time-resolved absorption spectra of the A exciton in CdSe are measured by using pico-second white-light pulses produced by a self-phase modulation technique. The absorption peak of the n = 1 A exciton shifts to the high-energy side due to the high-density effect. The magnitude of the shift reaches a maximum at 20 psec after the pulse excitation, which is considered to indicate that the time constant for the formation of the n = 1 excitons by band-to-band excitation is about 20 psec.