Aspects of alpha-particle scattering and structure of the nuclear surface

The interaction of α particles above 5 MeV with a 2s-1d target is dominated by resonances. It cannot be described only in terms of a mean-field one-body potential. An analysis of the elastic α-particle scattering by ²⁸Si encourages the comprehension of the resonance states to be mainly fragments of a mixed-parity band. In the present article, the angular distributions of particles scattered by ³²S are analyzed in terms of such bands. The analysis of new data from an experiment made at Florida State University reveals the existence of states that do not belong to the above bands. This follows from a coupled-channel analysis of the elastic and inelastic (2⁺) cross sections. An α-particle structure at the nuclear surface is suggested.     

The use of sulfide cluster-derived catalysts to understand the promotional effect in hydrotreatment catalysis

Sulfide cluster-derived ensembles are promising models of the active sites in commercial hydrotreatment catalysts. A series of sulfide clusters were adsorbed intact onto high-surface-area γ-alumina, magnesium oxide and activated carbon supports, then pretreated to produce highly dispersed catalytic ensembles with sizes similar to those of their precursor clusters. The activities of the bimetallic cluster-derived catalysts were significantly higher than those of the monometallic catalysts. We took this as evidence that direct interactions between molybdenum and the promoter element cause the promotional effect observed in commercial hydrotreatment catalysts. The hydrodesulfurization and hydrodenitrogenation activities correlated with the extent of molybdenum reduction. Our results suggested that the active sites in promoted hydrotreatment catalysts are centered on molecular-scale ensembles containing molybdenum, sulfur and the promoter element.     

Korrosion und Schutzanstriche

Ohne Zusammenfassung     

Korrosionsuntersuchung

Ohne Zusammenfassung     

The practical synthesis of a novel and highly potent analogue of bryostatin

Macrocycle 1 is a new highly potent analogue of bryostatin 1, a promising anti-cancer agent currently in human clinical trials. In vitro, 1 displays picomolar affinity for PKC and exhibits over 100-fold greater potency than bryostatin 1 when tested against various human cancer cell lines. Macrocycle 1 can be generated in clinically required amounts by chemical synthesis in only 19 steps (LLS) and represents a new clinical lead for the treatment of cancer.     

Preparative isolation of (+)-beta-eudesmol fromAmyris balsamifera

Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum distillation of the total oil. Step two was a medium pressure LC separation with an AgNO₃ impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related sesquiterpene alcohols (75% of the oil).