Stereocontrolled total syntheses of (±)-clovan-3-one and (±)-epi-clovan-3-one and a facile total synthesis of (±)-pseudoclovene-A

Stereocontrolled total syntheses of the bridged tricyclic ketones (±)-clovan-3-one (5) and (±)-epi-clovan-3-one (6) and a facile total synthesis of the tricyclic sesquiterpene (±)-pseudoclovene-A (3) have been successfully accomplished involving participation of an aryl intramolecular cyclisation of the bromophenol 11 as a key step.     

A unique series of dinuclear transition metal-polyradical complexes with a m-phenylenediamine spacer and their catalytic reactivity

A series of dinuclear transition metal complexes with either six or four iminosemiquinone radicals, in which the metal centres are separated by a distance of approximately 6.8 A, together with their catalytic reactivity is reported.     

On a generalised<Emphasis Type="Italic">ε</Emphasis>-control problem in Banach space

In this paper a linearε-control problem for a general objective function is considered by functional analytic approach. Existence and uniqueness of solutions are shown. The characterization of the solution is given in terms of a hyperplane.     

Cosmologies with Variable G and Λ from Action Principle

Cosmologies with variable G and are developed in this paper from an action principle, and some exact cosmological models are presented. These models indicate that the era of variable G and must have occurred, if at all, prior to other possible eras like radiation and dust.     

In-beam γ spectroscopy using DIC with a radioactive Ne beam

A study of deep-inelastic and multi-nucleon transfer reactions to populate neutron-rich O, Ne and F nuclei is here presented. The reaction under analysis employed a beam of radioactive ²⁴Ne at 7.9 AMeV, provided by the SPIRAL facility at Ganil, impingin on a ²⁰⁸Pb target. The reaction products have been detected in the VAMOS spectrometer in coincidence with gamma rays measured by the EXOGAM array. Preliminary results here presented show a selectivity in the population of states of different nature.     

X-ray photoelectron spectroscopy studies on core-shell structured nanocomposites

Core-shell nanostructures were grown in silica-based glasses. Copper-copper oxide and iron-iron oxide structures had diameters in the range 3-6 nm, with shell thicknesses ∼1-2 nm. Silver-lithium niobate core-shell nanostructures had diameters in the range 4.2-46 nm and thicknesses varying from 2.2 to 22 nm. X-ray photoelectron spectroscopy studies were carried out on all these specimens. The analyses of these results show the presence of Cu⁺/Cu²⁺, Fe²⁺/Fe³⁺ and Nb⁴⁺/Nb⁵⁺ valence states in the above three systems. Electrical resistivity data were fitted satisfactorily to the small polaron hopping model in the case of copper and iron-containing specimens. The presence of ions in the lithium niobate shell provides direct evidence of the formation of localized states between which variable range hopping conduction can be effected.     

String dynamics near a black hole

The dynamics of a string near a Kaluza-Klein black hole are studied. Solutions to the geodesic equations are obtained using the world sheet velocity of light as an expansion parameter. For a string falling into a magnetically charged black hole, it is shown that the compact dimension decreases with the world-sheet coordinate τ.