The evolution of polarization in an inhomogeneous birefringert,optically active medium

This note presents a method giving the change of polarization of an e.m. wave propagating in an inhomogeneous medium which is birefringent and optically active. The method has proved useful in a problem where the medium is a plasma with a magnetic field: it can be applied to other cases of interest, e.g. liquid crystals, as is here briefly discussed.     

Absolute proton stability in unified models of strong,weak and electromagnetic interactions

We show that the proton can be made absolutely stable, without introducing superheavy bosons, by imposing a global U(1) color symmetry on the Higgs couplings of the theory. Vector-like SU(5) and SU(6) models are discussed in detail.     

Hydrostatic pressure effects on the superconducting properties of Ag1−xSn1+xSe2

The superconducting transition temperature, T_c, of NaCl structure compounds in the series Ag_1?xSn_1+xSe₂ is found to be exceptionally sensitive to hydrostatic pressures up to 21 kbar. For five samples of varying composition, T_c is suppressed smoothly at a rate of ?(6?8)×10^?5K·bar^?1. These results are discussed with respect to the volume sensitivity of the electron-phonon interaction responsible for superconductivity.     

Su certe varietà algebriche intersezioni di quadriche od a sezioni curvilinee normali

Sunto è dato dall'Introduzione o, più sinteticamente, dall'Indice posto (nell'estratto) alla fine del lavoro. Dedico il presente lavoro all' amico carissimoBruno Finzi, in occasione del suo 70^o compleanno. Entrata in Redazione il 19 febbraio 1970.     

Metabolic profile of lettuce leaves by high-field NMR spectra

A detailed analysis of the proton high-field NMR spectra of aqueous and organic extracts of lettuce leaves is reported for the first time. A combination of COSY, TOCSY, (1)H-(13)C HSQC, (1)H-(13)C HMBC bidimensional sequences and DOSY was used to assign each spin system and to separate the components of the complex patterns. A large number of water-soluble metabolites belonging to different classes such as carbohydrates, polyols, organic acids and amino acids were fully assigned. Moreover, the complex spectra of metabolites extracted in organic solvents belonging to sterols, fatty acids, diacylglycerophospholipids, galactosyldiacylglycerols, sulpholipids, pheophytins, carotenoids and hydrocarbons were also assigned.     

The superconductivity of Sc5T4Si10 (T = Co,Rh, Ir) and isomorphous compounds

Superconductivity is reported for a new class of ternary compounds of general formula R₅T₄X₁₀ where R is Sc, Y or a rare earth, T a transition metal of the platinum or iron groups and X either Si or Ge. Critical temperatures up to 8.6 K are observed. The relationship with non-superconducting compounds of similar composition and structure is discussed.