Alcune osservazioni sul prodotto din forme lineari reali non omogenee

Sunto Se d(Λ)μ(ρ) è il minimo non omogeneo, rispetto al punto ρ, del prodotto di n forme reali omogenee, si studia la successione {μ(hρ)} al variare di h intero.

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Summary Let d(Λ)μ(ρ) the inhomogeneous minimum, in the point ρ, of the product of n homogeneous linear real forms. Some results on μ(hρ), for h an integer, are given.

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Lavoro eseguito nell'ambito dell'attività del gruppo di ricerca n^o 40 del Comitato per la Matematica del C. N. R. (1961–62).     

Sui sistemi omaloidici di quadriche nello spazio ordinario

Ad Antonio Signorini nel suo 70^mo compleanno.     

Antiferromagnetism and hole pair checkerboard in the vortex state of high T(c) superconductors

We propose a microscopic state for the vortex phase of BSCO superconductors. Around the vortex core or above H(c2), the d wave hole pairs form a checkerboard localized in the antiferromagnetic background. We discuss this theory in connection with recent STM experiments.     

Roles of stiffness and excluded volume in DNA denaturation

The nature and the universal properties of DNA thermal denaturation are investigated by Monte Carlo simulations. For suitable lattice models we determine the exponent c describing the decay of the probability distribution of denaturated loops of length l, P approximately l(-c). If excluded volume effects are fully taken into account, c = 2.10(4) is consistent with a first order transition. The stiffness of the double stranded chain has the effect of sharpening the transition, if it is continuous, but not of changing its order and the value of the exponent c, which is also robust with respect to inclusion of specific base-pair sequence heterogeneities.     

An efficient procedure for the preparation of (E)-alpha-alkylidenecycloalkanones mediated by a CeCl(3) x 7H(2)O-NaI system. Novel methodology for the synthesis of (S)-(-)-pulegone

2-Alkylidenecycloalkanones are powerful synthons used as the key intermediates in many important syntheses. Because of their potential, a general method of preparation from readily available starting materials, under very mild conditions, was considered to be worthwhile. Cerium(III) chloride heptahydrate in combination with sodium iodide in refluxing acetonitrile promotes a regio- and stereoselective beta-elimination reaction to (E)-2-alkylidenecycloalkanones in 2-(1-hydroxyalkyl)cycloalkanones. The synthetic value of the present procedure is demonstrated by the synthesis of monoterpene (S)-(-)-pulegone (8) in its optically active form.     

A fast pairwise evaluation of molecular surface area

A fast and general analytical approach was developed for the calculation of the approximate van der Waals and solvent-accessible surface areas. The method is based on three basic ideas: the use of the Lorentz transformation formula, a rigid-geometry approximation, and a single fitting parameter that can be refitted on the fly during a simulation. The Lorentz transformation equation is used for the summation of the areas of an atom buried by its neighboring contacting atoms, and implies that a sum of the buried pairwise areas cannot be larger than the surface area of the isolated spherical atom itself. In a rigid-geometry approximation we numerically calculate and keep constant the surface of each atom buried by the atoms involved in 1-2 and 1-3 interactions. Only the contributions from the nonbonded atoms (1-4 and higher interactions) are considered in terms of the pairwise approximation. The accuracy and speed of the method is competitive with other pairwise algorithms. A major strength of the method is the ease of parametrization.     

A "Nitrate Route" for the low temperature "Fast SCR" reaction over a V2O5-WO3/TiO2 commercial catalyst

A novel mechanism is proposed for the Fast SCR reaction of NH(3), NO and NO(2) at low temperature involving the formation of ammonium nitrate as intermediate and its subsequent reaction with NO as the rate determining step.     

The different role of Cu++ and Zn++ ions in affecting the interaction of prion peptide PrP106-126 with model membranes

Differential scanning calorimetric (DSC) experiments have shown that the ability of PrP106-126 to perturb 1,3-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) model membranes is differently affected by Cu(++) and Zn(++) ions.