Analysis of photodecomposition of gaseous chlorobenzene by KrF excimer laser.

Gaseous monochlorobenzene was irradiated with KrF excimer laser (248 nm) under reduced pressure. The photodecomposition was an apparent first order reaction. When the system contained no additive gas, the photolysis was found to give benzene (conversion yield: 49%) in the gas phase and many unidentified products in the solid phase. On the other hand, in the presence of oxygen, carbon dioxide (10%), carbon monoxide (16%), hydrogen chloride (52%) and acetylene (2%) are produced and the peaks shown on the gas chromatogram of the solid phase were effectively suppressed.     

Improvement of the fiber raman soliton laser for femtosecond optical pulse generation

Femtosecond optical pulses generated from a synchronously pumped fiber Raman soliton laser (FRASL) have been shown to have large excess noise and high background light (i.e., the pedestal) levels. In this paper, to improve the FRASL, the operation characteristics of the FRASL are investigated both theoretically and experimentally. It is shown that real femtosecond soliton oscillation in the FRASL can be obtained only when the soliton self-frequency shift (SSFS) effect in the fibers is suppressed and proper choices of both the Stokes oscillation wavelength and the pump power level are required for the SSFS suppression in the FRASL. By using a tunable all-fiber Raman ring laser, optical pulses as short as 400 fs with a low white AM noise level of -120 dBc / Hz have been generated from the compact FRASL with SSFS suppression. Based on the theoretical analyses, we propose to use an intracavity saturable absorber to prevent the generation of high-level Stokes background light in the FRASL, and the feasibility of this method is shown by numerical simulations.     

Asymptotic constraint for chiral condensation of Coulomb gauge QCD

We study the³ P ₀ quark-antiquark pair condensation in QCD, representing the gluon-interaction approximately by instantaneous Coulomb plus Breit potential. Particular attention is paid to non-uniqueness of the solution of the gap equation. The genuine dynamical solution can be characterized by a rapidly convergent behavior at large momentum, as was recognized in covariant formulations of Landau gauge. We impose the required behavior and make a numerical study of the chiral condensation.     

Constituents of the roots of Boerhaavia diffusa L. III. Identification of Ca2+ channel antagonistic compound from the methanol extract

Two known lignans, liriodendrin and syringaresinol mono-beta-D-glucoside, have been isolated from the methanol extract of the roots of Boerhaavia diffusa L. (Nyctaginaceae), and the former compound was found to exhibit a significant calcium (Ca2+) channel antagonistic effect in frog heart single cells using the whole-cell voltage clamp method. Reexamination of the carbon-13 nuclear magnetic resonance (13C-NMR) spectra of these compounds was also carried out by the use of two-dimensional NMR techniques including a 1H-detected heteronuclear multiple bond connectivity (HMBC) experiment, and it was found that the previous signal assignments for C-1' and C-4' have to be revised.     

Treatment of droplike clusters in nucleation theory using Reiss's method

The expression of the correction factor in nucleation theory is derived by extending the method Reiss used recently. is the factor appearing in the number of critical nuclei (formed as a vapor condenses into liquid drops) as a correction to the conventional theory. It is shown that=p _l / _g /kT, wherep _l is the pressure of the liquid phase inside the drop, _g , is the volume per molecule in the vapor phase,k is the Boltzmann constant, andT is the absolute temperature. The difference between this and Reiss's expression isp _l , which replaces hisp _g (the vapor pressure in equilibrium with the drop). The derived in this paper is compatible with the expression= _g / _l ( _l is the molecular volume in the liquid phase) previously proposed by the present author.     

Meta/para-selectivity variation by sulfide/sulfoxide conversion of 6-substituted β-cyclodextrin. Hydrolyses of nitrophenyl acetates. ag

Hydrolyses of m- and p-nitrophenyl acetates by 6-deoxy-6-alkylthio-β-cyclodextrins and the corresponding sulfoxides were studied to show that the small chemical conversion from the sulfides to the sulfoxides led to a change of meta/para-selectivity in the hydrolysis of the β-cyclodextrin moiety.     

Picosecond time-resolved observation of photoinduced charge separation from the singlet excited state of porphyrin-quinone model systems

The charge transfer state formed from the S₁ state of porphyrin-p-benzoquinone (BQ) model systems in solution has been observed combining octaethylporphyrin and BQ by methylene chains of various lengths. The lifetime of the electron transfer state depends upon the length of the methylene chain and the nature of the solvent.     

Metal-catalyzed organic photoreactions. Photoreaction of olefins with 2-chloroacetophenone in the presence of silver trifluoromethanesulfonate

Under UV irradiation with 2-chloroacetophenone in the presence of silver trifluoromethanesulfonate in acetonitrile, acyclic olefins gave naphthalenone derivatives, while cyclic olefins gave phenanthrenone derivatives in moderate yields.     

Structure of ophiorines A and B; novel type gluco indole alkaloids isolated from ophiorrhiza spp.

Two novel type gluco indole alkaloids, ophiorines A and B, were found in Rubiaceous plants, Ophiorrhiza japonica B1. and O. kuroiwai Mak., and their structures were elucidated by chemical and spectroscopical methods.