Laurepinnacin and isolaurepinnacin,new acetylenic cyclic ethers from the marine red alga laurenciapinnata yamada

The Structure elucidation of the title compounds, two new insecticidal components of the marine red alga $\text{Laurencia}$$\text{pinnata}$ Yamada, is described.     

A facile formation of cyclic selenuranes and a cyclic selenurane oxide in the reaction of 2-methylseleno- and 2-phenylselenobenzoic acids and their derivatives with t-butyl hydroperoxide

The reaction of 2-methylselenobenzoic acid with 1,1′-carbonyldiimidazole followed by addition of t-butyl hydroperoxide gave cyclic selenuranes $\text{2a}$ and $\text{3a}$, suggesting the intramolecular insertion of the neighboring selenium atom into the OO bond of t-butyl 2-methylselenoperoxybenzoate. In the reaction of 2-phenylselenobenzoyl chloride with t-butyl hydroperoxide, cyclic selenurane $\text{2b}$ and the oxide $\text{7}$ were obtained.     

Confirmation of the structures of kuwanons G and H (albanins F and G) by partial synthesis

Conclusive evidence is presented supporting structures $\text{1}$ and $\text{2}$ for two natural Diels-Alder adducts isolated from mulberry and designated as kuwanon G (albanin F, moracenin B) and Kuwanon H (albanin G, Moracenin A).     

Highly stereoselective reduction of α-methylthio and α-phenylthio ketones synthesis of syn- and anti-β-methylthio- and β-phenylthioalcohols

Reduction of α-methylthio and α-phenylthio ketones 1 with L-Selectride gave syn-alcohols 2 in high stereoselectivity except when R¹ was cyclohexyl group, while reduction with Zn(BH₄)₂ gave the isomeric anti-alcohols 3 provided R₃ was methyl group.     

Vietoris-Begle theorem for spectral pro-homology

Dydak and Kozlowski (1991) obtained a generalization of the Vietoris-Begle theorem for the cohomology theories induced by CW spectra. In this note we prove a dual of their theorem involving the pro-homology theories induced by CW spectra.     

Photoviscoplastic investigations of slip-line fields and principal-stress trajectories in viscoelastoplastic strip for drawing with back tension

Photoviscoplasticity is applied to the drawing with back tension through rollers and wedge-shaped dies in model tests of plane-strain state. The effects of the back tension on the slip-line fields and on the principal-stress trajectories for the strips are discussed in the light of experimental results obtained from the model tests. Actual strips are considered as viscoelastoplastic media in the actual drawing processes. The model specimens used are softened celluloid as the viscoelastoplastic medium for the strip and Araldite as the glassy elastic medium for the dies. At a suitable experimental temperature, the viscoelastoplastic strip is drawn viscoplastically through the gap between the dies mentioned above. The slip-line fields, the principal-stress trajectories in the strip and the normal pressure on the contact surface are greatly influenced by the effect of the back tension.     

Magnetic form factor of ordered Fe3Pt alloy

Magnetic form factor of the ordered Fe₃Pt alloy was measured by means of the polarized neutron diffraction technique. From the form factor analysis, localized moments of Fe and Pt are determined as μ_Fe = 2.03 ± 0.02 μ_B, μ_Pt = 0.36 ± 0.08 μ_B at room temperature respectively. The fractional population of T_2g levels for Fe atoms is also determined as 0.52 ± 0.02.