Gibb's variational principles for the equilibrium of continuous systems with an interface

A mathematical formulation of the Gibbs variational principle is supplied for the equilibrium of a system of to fluids with an interface adsorbing or not and permeable or not. These properties of the interface are represented by suitable constraints for the admissible variations.

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Sunto Viene fornita una rigorosa formulazione del principio variazionale di Gibbs per l'equilibrio di un sistema di due fluidi con un'interfaccia assorbente o non ed impermeabile o non. Dette proprietà dell'interfaccia sono tradotte da opportuni vincoli per le variazioni ammissibili.

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Work partially supported by G.N.F.M. of the Italian C.N.R.     

Remarks on bifurcation for elliptic operators with odd nonlinearity

On estimating the eigenvalues for a class of semilinear elliptic operators, we obtain bifurcation and comparison results concerning the eigenvalues of some related linear problem.     

The FIGARO II experiment: a general outline of the mission and the principal scientific results

Summary The FIGARO II (French Italian Gamma-Ray Observatory) experiment has been launched successfully three times: in July 1986 from Milo (Trapani), in November 1988 from Charleville (Australia) and in July 1990 again from Milo. In the first flight the observational program was limited to the Crab pulsar PSR0531+21 only because of a telemetry failure: the high sensitivity of FIGARO II allowed an accurate study of the pulse shape as well as a phase-resolved spectroscopy. It was also possible to evaluate the dispersion measure of the Crab pulsar at the flight date from the time delay between gamma-ray and radio pulses. The major results of the second flight were a stringent upper limit to the low-energy gamma-ray flux from PSR 0833-45 (Vela pulsar)—well below the detection claimed by the UCR group —and the observation of a strong emission in the 0.511 MeV annihilation line from the inner region of our Galaxy. The data acquired in the third flight are still under analysis, but preliminary results suggest changes in the shape of the pulse profile. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Syntheses,characterization, and Mossbauer study of Sn(II and Sn(IV) complexes of the cyclopentadienedithiocarboxylate ligand

The preparation and physical characterization of the tetraethylammonium salts of bis(cyclopentadienedithiocarboxylate)stannate(II) and tris(cyclopentadienedithiocarboxylate)stannate(IV) are reported. The coupling constants for the ring protons of the coordinated and uncoordinated ligand indicate that the oxidation state variation of the metal has little effect on the electronic structure of the ligand. The Mössbauer parameters for the Sn(IV) complex (δ = 1.05 ± 0.02 mm/sec with respect to SnO₂, Line width = 1.05 mm/sec) are normal for a pseudo-octahedral complex. The values for the Sn(II) complex are somewhat abnormal for a Sn(II) complex (δ = 0.29 mm/sec, Line width = 1.65 mm/sec) and are interpreted as indicative of metalmetal bonding in the molecular structure.     

Theoretical analysis of resonant raman scattering: Simulations of lineshapes and excitation profiles

The steady-state response of a three-level system in the presence of a strong laser field is described with the density operator formalism, in order to derive an analytical expression for the intensity of resonance Raman scattering. The Liouville equation for the density operator is written in quantum form for both the molecular system and the radiation field, making use of the dipole and rotating-wave approximations for the matter-radiation interaction, and of the Markov approximation for the molecular decays. The equation is solved exactly for the laser field, and in perturbative way for the generated field. The results account for power broadening of the generated line. Rabi intensity-dip of the generated signal, and for the excitation profiles in the Franck-Condom approximation.     

Sur les groupes engendrés par une classe dep-involutions

Sans résuméCe travail a reçu une contribution par le CNR, pendant la visite de l'auteur à l'Université de Toulouse.     

A novel catalyzed C-H insertion reactions of hydrogen peroxide by poly(4-vinylpyridine)/methyltrioxorhenium systems

Novel poly(4-vinylpyridine) supported MTO compounds were effective heterogeneous catalysts for the C-H insertion reactions of H₂O₂ into some representative hydrocarbon derivatives. The most relevant outcomes of these oxidations are described.     

Degradation of copolymers of acrylonitrile and styrene in alkaline dimethyl sulphoxide solution

Investigations on the alkaline degradation of copolymers of acrylonitrile and styrene dissolved in dimethyl sulphoxide were carried out by means of viscometry, titrimetry and GPC measurements. The degradation reaction takes place with alkali concentrations higher than 1·3–1·4 × 10^?4 moles of KOH per gram of copolymer. Four to five new macromolecules arise from each starting macromolecule. A consumption of 1·3–1·5 moles of KOH was calculated for each new macromolecule formed.