Modification of Silica by Liquid Polybutadienes Containing Alkoxysilane Groups

Summary : The present work describes a method to modify the surface of silica, reducing its polar character and making it compatible and dispersible into hydrocarbon based elastomers. A liquid low molar mass polybutadiene (PB) was grafted with mercaptopropyltrimethoxysilane (MPTS) via radical addition of the thiol group to the double bonds. The silanized PB was reacted with silica via thermal condensation with its silanol groups. ²⁹Si NMR spectra showed that the condensation reaction of the trifunctional silane involved one or two alkoxy groups, while the third alkoxy group remained unreacted, probably for steric reasons. The characterization of the functionalized silica particles was performed by contact angle measurements and TGA analysis.     

Determination of the conformation of diethylmethyl-2-[p-(o-propoxybenzamido)benzoyloxy]ethylammonium bromide in solution by measurement of selective proton spin–lattice relaxation rates

The relative conformation of the aromatic rings and the amide bridge of diethylmethyl-2-[p-(o-propoxybenzamido)benzoyloxy]ethylammonium bromide has been established by a combined analysis of non-selective, single-selective and double-selective pulse experiments using, as a basis of comparison, the Dreiding molecular model of the compound.     

Studies on the synthesis of heterocyclic compounds. Synthesis of 1,3,2-benzoxathia- and 1,3,2-benzodioxastibole derivatives

The preparation of 1,3,2-benzoxathia- and 1,3,2-benzodioxachlorostiboles (IIa-b) by reaction of antimony trichloride with 2-hydroxythiophenol (Ia) or 1,2-benzodiol (Ib) is described. The halogen was easily removed. Thus a Wurtz-like reaction gave the distibole compounds (IVa-b), which were also produced by organolithium compounds or pyridine. The compounds Va-b were obtained with sodium hydroxide, ethoxide and phenoxide, but spiran derivatives VIIa-b, of antimony, were obtained by treating IIa-b with 2-hydroxythiophenol or 1,2-benzodiol in the presence of triethylamine. The structure of the prepared compounds was determined by spectro-scopic methods.     

Studio di una disequazione quasi-variazionale relativa ad un problema di filtrazione in tre dimensioni

Summary A 3-dimensional problem related to the theory of fluid flow through porous media is translated into a quasi-variational inequality: an existence theorem is proved.

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Entrata in Redazione il 17 marzo 1976.

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Lavoro svolto nell'ambito del ? Gruppo Nazionale per l'Analisi Funzionale e le sue applicazioni ? e del ? Laboratorio di Analisi Numerica ? di Pavia del C.N.R.     

A characterization ofC 1-convex sets in Sobolev spaces

In this paper we prove that, ifK is a closed subset ofW ₀ ^1,p (Ω,R ^m ) with 1<p<+∞ andm≥1, thenK is stable under convex combinations withC ¹ coefficients if and only if there exists a closed and convex valued multifunction from Ω toR ^m such that The casem=1 has already been studied by using truncation arguments which rely on the order structure ofR (see [2]). In the casem>1 a different approach is needed, and new techniques involving suitable Lipschitz projections onto convex sets are developed. Our results are used to prove the stability, with respect to the convergence in the sense of Mosco, of the class of convex sets of the form (*); this property may be useful in the study of the limit behaviour of a sequence of variational problems of obstacle type. This article was processed by the author using the Springer-Verlag TEX mamath macro package 1990     

Intrinsic acidity and basicity of neutral and ionic species of some polyether-ester compounds as shown by mass spectrometry

The mass spectrometric behaviour of benzo-[o]-1,4,7,10,13-pentaoxacycloheptadecane-14,17-dione (1), 3,6,9,12,15-pentaoxabicyclo[15.3.1]heneicosa-1(21),17,19-triene-2,16-dione (2) and 1,15-dioxo-2,5,8,11,14-pentaoxa[15](1,4)benzenophane (3) has been studied in detail with the aid of linked scans, mass-analysed ion kinetic energy spectra, collisionally activated decomposition experiments, exact mass measurements and different ionization techniques (electron impact, positive and negative ion chemical ionization, charge exchange, electron attachment). The very low abundance of molecular ions and the presence of abundant [M + H]⁺ and [M – H]⁺ ions under electron impact conditions indicate the presence of acidic and basic sites in the molecular ions and neutral molecules, respectively.     

On the quantum theory of sequential measurements

The quantum theory of sequential measurements is worked out and is employed to provide an operational analysis of basic measurement theoretical notions such as coexistence, correlations, repeatability, and ideality. The problem of the operational definition of continuous observables is briefly revisited, with a special emphasis on the localization observable. Finally, a brief overview is given of possible applications of the theory to various fields and problems in quantum physics.