NMR relaxation investigation of water “ordering” in aqueous lysozyme solutions

Lysozyme in aqueous dilute solution has been chosen as a model system to investigate the state and the mobility of water molecules near macromolecular surfaces. The dependence of the water proton NMR T₁ on temperature and on denaturing processes is interpreted in terms of long-range interactions giving rise to“ordering” of water, as seen on the NMR time scale.     

On the variational formulation for linear initial value problems

Summary The paper shows the key place of the choice of the bilinear form in order to give a variational formulation to a given problem. In particular it is shown how the use of a convolution bilinear form makes possible a variational formulation for linear initial value problems. A critical survey of the three main methods that was devised in the past to solve the same problem is done.

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Sunto. La nota mette in evidenza il ruolo fondamentale della scelta di una forma bilineare al fine di dare formulazione variazionale ad un dato problema. In particolare è mostrato come l'uso di una forma bilineare di convoluzione renda possibile la formulazione variazionale dei problemi ai valori iniziali. Si fa un esame critico dei tre principali metodi che sono stati escogitati nel passato per risolvere lo stesso problema.

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This work has been sponsored by the Consiglio Nazionale delle Ricerche.

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Entrata in Redazione il 19 novembre 1971.     

Origin of arsenic pollution in Southwest Tuscany: comparison of fluvial sediments

The Colline Metallifere in SW Tuscany are characterized by strong anomalies in arsenic concentrations and distribution. The area is sparsely populated and largely wild, though it has been subject to human impact due to mining and metal processing since Etruscan and Roman times. In the Middle Ages it was exploited intensively for silver and copper. Until 1995, pyrite (FeS2) was mined and roasted to produce sulphuric acid and iron. Hypotheses based on geological and mineralogical factors formulated in the last 20 years have failed to explain the peculiar distribution of arsenic in the Colline Metallifere. Here we report preliminary results of widespread sampling and analysis of the fluvial sediments of rivers originating in this mining area. The data was analysed in relation to the archaeological features of the area, since the presence of ancient mining and ore processing sites can shed light on the peculiar distribution of arsenic. Comparison of data from two rivers and their respective contaminated and uncontaminated coastal lagoons also clarified the general mechanisms of arsenic mobility, pinpointing the source of arsenic contamination. The study methods also promise to be useful for discovering unknown archaeological sites.     

Contributi alla teoria dei residui per le funzioni di due variabili complesse

Sunto Si assegna una condizione necessaria e sufficiente per la validità di una formula diCaccioppoli generalizzazione2-dimensionale dell'indicatore logaritmico. A Mauro Picone nel suo 70^mo compleanno.     

Trees with minimal index and diameter at most four

In this paper we consider the trees with fixed order n and diameter d≤4. Among these trees we identify those trees whose index is minimal.     

Liquid Crystalline Phases in 4-Acetyl-4′-n-Alkanoyloxy-Azobenzenes

Abstract

The preparation and melting behaviour of the homologous series of 4-acetyl-4′-n-alkanoylox-azobenzenes, CH₃-CO-C₆H₄-N?N-C₆H₄-O-CO-(CH₂) _n -CH₃, (with n ranging from zero to 16) is reported. The melting behaviour has been investigated by means of thermal microscopy and differential scanning calorimetry. The experimental results indicate for almost all the compounds the presence of solid state polymorphism and a type A smectic; for one compound a type B smectic phase is also present. Some homologs present, in addition, a nematic phase.     

Reflecting diffusions and hyperbolic Brownian motions in multidimensional spheres

We consider diffusion processes $ {{\left( {{{{\underline{\mathrm{X}}}}_d}(t)} \right)}_{{t\geqslant 0}}} $ moving inside spheres $ S_R^d $ ? ? ^d and reflecting orthogonally on their surfaces. We present stochastic differential equations governing the reflecting diffusions and explicitly derive their kernels and distributions. Reflection is obtained by means of the inversion with respect to the sphere $ S_R^d $ . The particular cases of Ornstein–Uhlenbeck process and Brownian motion are examined in detail. The hyperbolic Brownian motion on the Poincaré half-space ? _d is examined in the last part of the paper, and its reflecting counterpart within hyperbolic spheres is studied. Finally, a section is devoted to reflecting hyperbolic Brownian motion in the Poincaré disc D within spheres concentric with D.