An EPR study on ancient and newly synthesised Egyptian blue,

Two sets of ancient roman Egyptian blue (EB) samples and one set of EB samples synthesised in our lab, were analysed by EPR spectroscopy, a technique not commonly used in this field. The spectroscopic parameters obtained were used to attempt the discrimination of the provenance and of the manufacturing techniques of the investigated samples. The results obtained show that EPR technique could be very useful for this purpose. Furthermore, the similarity of the obtained parameters between the ancient and new samples testify the successful attempt to reproduce the EB according to the chemical knowledg

Aragonite in Roman Wall Paintings of the VIII° Regio, Aemilia, and X° regio, Venetia et Histria

ABSTRACT In the Roman wall paintings different white colours were used, named Paraetonium, Melinum, Anularia, Eretria, Argentaria, etc. FTIR, Raman spectroscopy and X-Ray diffraction were applied to study different white pigments, such as calcite, aragonite, dolomite and huntite, white carbonates present in archaeological findings from roman walls in the Mediterranean region. This study showed that it is possible to distinguish and identify these components in white colours. About 450 samples of Roman wall paintings were analysed and it was observed that often aragonite is associated to precious coloured pigments. On the basis of the obtained results some considerations about the period in which the different kinds of white pigments were used are proposed

Studio preliminare sulla produzione e il degrado di vetri potassici e sodici come modelli di vetrate artistiche e di vetri industriali in ambiente confinato

This study concerns the alteration of glass in confined environment , characteristic of the industrial glass containers stored inpallets before filling and of the artistic stained-glass windows protected by a glazing system . In order to better understandin the different influence of the parameters of glass alteration (chemical durability, temperature, relative humidity and exposition time), an ex-novo low-expensive system ha sbeen designed and realized for the reproduction of a confined environment and for the measure and control of relative humidity and temperature. Soda-lime silica glass and potash-lime silica glass samples have been produced as models of glass containers and medieval artistic stained glass windows repectively. Outdoor and indoor (in stove) expositions of the glass samples have been performed and the weathering of the samples has been investigated by different analytical techniques, such as optical microscopy, SEM-EDS and Micro-IRRS

Stanza n° 50 - La Matematica

Monografia per l'Enciclopedia telematica multimediale "E-dotto" - Photolibrary Educational Alinari

Spectroscopic methods for the analysis of celadonite and glauconite in Roman green wallpaintings

One set of samples from wall paintings of the Xth Regio of Italy containing green colours was analysed exploiting different spectroscopic techniques, aiming to identify the pigments used. The possibility to distinguish between glauconite and celadonite, the most common green pigments used in such paintings, was of particular interest. Samples of celadonite from Monte Baldo and glauconite from Belgium were considered as standard materials for comparison. The results obtained using FTIR, EDS, AAS, Colorimetry, Raman and EPR spectroscopies were compared for the identification of the green pigments

EPR study of Roman age mortars found in North-Eastern Italy

Congresso triennal

Comparative kinetic study between native and chemically modified Cu,Zn superoxide dismutases

The kinetic behaviour of native bovine erythrocyte Cu,Zn superoxide dismutase (N-SOD) and of its derivatives by reaction with polyethylene glycol, acetic and succinic anhydrides has been investigated here in detail. Their responses to changes of pH and ionic strength (I) have been used as a probe for quantitatively displaying the relevance to kinetic rate constant of superficial positive charges driving the superoxide ion (O2-) toward the enzyme's active site. Overall kinetic trends indicate that this long-range O2- electrostatic guidance is essentially due to the positive charges of the amino-acid residues Lys-120 and Lys-134 which are strategically located around the active site. The comparison between the kinetic data obtained from N-SOD and those from polyethylene-glycolated SOD (PEG-SOD) enabled us to state that in PEG-SOD an O2(-)-steering positive electrostatic force, halved in comparison with N-SOD, is still operating, and that only Lys-120 is linked in the reaction of N-SOD with PEG. Elimination of the electrostatic driving force, carried out either by deprotonation of lysine amino groups at high pH, or by their neutralization with succinic anhydride and acetic anhydride, or by ionic screening at high ionic strength, always lowered the kinetic rate constant to a value of approx. 3 x 10(8) M-1.s-1. This value is about 15 times smaller than that measured in the presence of the reactant-steering mechanism and represents the k value of the reaction limited by pure diffusion. Finally, the kinetic behaviour of acetylated SOD and succinylated SOD demonstrated the inhibitor effect of OH- at strongly alkaline pH