Lobohedleolide and (7Z)-lobohedleolide,new cembranolides from the soft coral lobophytum hedleyi whitelegge

The structures of lobohedleolide (1) and (7Z)-lobohedleolide (2), two new cembranolides containing the α,β-unsaturated carboxylic acid system isolated from the Japanese soft coral Lobophytum hedleyi Whitelegge, were elucidated from spectral and chemical evidence, and the absolute configuration of (1) was determined by X-ray analysis of its p-bromophenacyl ester (9). Lobohedleolide (1) showed growth inhibition of the in vitro Hella cells.     

Regeneration of small eddies by data assimilation in turbulence

The effect of data assimilation of large-scale eddies on small-scale eddies in turbulence is studied by direct numerical simulations (DNSs) of Navier-Stokes turbulence with Taylor microscale Reynolds numbers up to 179. The DNSs show that even if the data of small-scale eddies are lost at some initial instant, they can be regenerated from the data of large-scale eddies under the condition that Fourier modes with wave number less than a critical wave number k(*) are continuously assimilated, where k(*) approximately 0.2eta(-1) with eta identical with(nu(3)/epsilon)(1/4), epsilon the mean energy dissipation rate, and nu the viscosity.     

Measurement of Gamma-Rays from 11ΛB and 12ΛC

From the ^12 C（π^＋,K^＋）^12 AC reaction the γ -rays of 261.6±0.24 ke V（7/2^＋ →5/2^＋）and 1481.7±0.7 ke V（1/2^＋ →5/2^＋） of ^11 A B,and 2667.3±2.8 keV（1^- 2 → 2^- 1）of ^12 A C hypernuclei have been identified using a large germanium detector array Hyperball2 at K6 beam line of KEK. The observed energies of the transitions 1481.7keV and 261.6 keV are significantly different from the values predicted by the shell model using the △ and SN parameters determined from the ^7 △ Li data.     

The commutator algebra of a nilpotent matrix and an application to the theory of commutative Artinian algebras

We show a number of properties of the commutator algebra of a nilpotent matrix over a field. In particular we determine the simple modules of the commutator algebra. Then the results are applied to prove that certain Artinian complete intersections have the strong Lefschetz property.     

Metallocene bis(perfluoroalkanesulfonate)s as air-stable cationic Lewis acids

Zirconocene and titanocene bis(perfluorooctanesulfonate)s were synthesized. In contrast to the corresponding triflates and perchlorates, these compounds are air- and water-stable. They were proved to be ionic on the basis of conductivity measurements and X-ray analysis, allowing these complexes to be stored for months. The strong Lewis acidity of these cationic metallocene species, which was proved by ESR study, enabled catalytic glycosylation.     

Synthesis and spectroscopic study of diphenylamino-substituted phenylene-(poly)ethynylenes: remarkable effect of acetylenic conjugation modes

A series of diphenylamino-substituted phenylene-(poly)ethynylenes were successfully synthesized by a combination of Sonogashira coupling and double elimination protocol of β-substituted sulfones. When UV-light was irradiated, the amino-substituted phenylene-(poly)ethynylene emitted strong luminescence. The emission underwent a large bathochromic shift in polar solvent because of stabilization of their charge-separated excited states. Analyses of fluorescence life times of aminoacetylenes revealed that radiationless process was suppressed in the polar solvent CH₂Cl₂, resulting in high quantum yields.     

Assessment of fluoroalkyltin compounds as fluorous Lewis acid catalysts

The synthesis of a variety of organotin compounds with 1H, 1H, 2H, 2H‐perfluorooctyl groups is reported, together with an improved method for the corresponding distannoxane. Unique properties of this compound are disclosed in terms of fluorophilicity and activity as a Lewis acid catalyst in comparison with other mono‐nuclear derivatives. A new criterion for obtaining high solubility in fluorocarbon solvents is presented. Copyright © 2003 John Wiley & Sons, Ltd.