Laboratory study of silicates and application to cometary dust

Summary The mass absorption coefficients of some glassy and crystalline silicates of astrophysical relevance have been measured. We produced and characterized also synthetic silicates of olivine type since this material is considered one of the most likely components of cometary dust grains. The experimental data are used to fit the emission feature observed in the Comet Halley spectrum between 8 and 13 μm. Satisfactory results are obtained by using synthetic olivine mixed with a small amount (5%) of crystalline grains. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

(2,3)-generation of PSp(4, q), q = p n,p ≠ 2,3

In this paper we show that the symplectic group PSp(4, q), q = pⁿ, p ≠ 2,3, is generated by an involution and an element of order 3.     

Laboratory tests on glycosidase preparations in wine

The secondary glycosidasic activity of pectinase preparations is used to release flavour active compounds of wine. In order to identify any undesirable effects of other collateral enzymatic activities, laboratory tests were carried out using two commercial preparations: NOVAROM G (Novo-Nordisk) and AR 2000 (Gist-Brocades). A pool of wines was obtained by blending two white wines from neutral grapes (Chardonnay and Verdeca) and a red wine from aromatic grapes (Aleatico). The experiment was carried out by adding each enzymatic preparation to the sample and analysing, by gas chromatography, with flame ionisation and mass spectrometric detection, the free aroma compounds after 15 and 30 days. In the first 15 days, the glycosidasic activity of the NOVAROM G brought about a considerable increase in the wine’s free terpenic content, especially nerol, geraniol and citronellol. After 30 days, further increases in all terpenic compounds were observed. The AR 2000, after 15 days, brought about the release of a conspicuous amount of terpenes, more than the previous enzymatic preparation, which further increased after 30 days. Throughout the test period, the enzymatic preparation, NOVAROM G, had no effect on the content of the acetates of the higher alcohols, the compounds associated with the banana-pineapple (isoamyl acetate) and rose (2-phenyl ethyl acetate) scents. However, the AR 2000 brought about a rapid hydrolysis of total acetates, which caused a fifty percent reduction in isoamyl acetate after 15 days and continued to decline until, after 30 days, the remaining concentration was below the perception threshold. Neither of the enzymatic preparations, however, provoked significant effects on the ethyl esters of the fatty acids compared to the control wine. In addition, the AR 2000 revealed esterase activity involving fixed acids, such as malic acid and succinic acid, with a conspicuous formation of diethyl malate and diethyl succinate, which became more marked after 30 days.     

A Geometric Characterization of Viable Sets for Controlled Degenerate Diffusions

For a general controlled diffusion process and an arbitrary closed set K we study the viability, or weak invariance, or controlled invariance, of K, that is, the existence of a control for each initial point in K keeping the trajectory forever in K. By viscosity solutions methods we prove a simple necessary and sufficient condition involving only a deterministic second-order normal cone to K and the data of the diffusion process. We also give an extension to stochastic differential games.     

Blue-emitting mesoporous films prepared via incorporation of luminescent Schiff base zinc(II) complex

Highly fluorescent materials have been prepared by incorporation of a zinc complex in mesoporous silica thin films with ordered pore structure. The zinc complex has been introduced into the mesoporous materials via impregnation in an ethanol solution. The incorporation into the films has been monitored by UV–Vis, Fourier transform infrared spectroscopy and spectroscopic ellipsometry. After 18 h of immersion in the doping solution the films showed strong blue emission, increase in the refractive index. Leaching experiments performed by immersing the samples in ethanol or tetrahydrofuran have shown that the chromophore is retained in the porous matrix.

Putative palytoxin and its new analogue,ovatoxin-a,in <Emphasis Type="Italic">Ostreopsis ovata</Emphasis> collected along the ligurian coasts during the 2006 toxic outbreak

In this article we report on the liquid chromatography tandem mass spectrometry (LC-MS) investigation of plankton samples collected in the summer of 2006 along the Ligurian coasts, coinciding with a massive bloom of the tropical microalga Ostreopsis ovata. LC-MS analyses indicated the occurrence of putative palytoxin along with a much more abundant palytoxin-like compound never reported so far, which we named ovatoxin-a. On the basis of molecular formula, fragmentation pattern, and chromatographic behavior, the structure of ovatoxin-a appeared to be strictly related to that of palytoxin. We report also on the analysis of cultured O. ovata, which was necessary to unequivocally demonstrate that putative palytoxin and ovatoxin-a contained in field samples were actually produced by O. ovata itself.     

Energy dispersive X-ray diffraction potentiality in the field of cultural heritage: simultaneous structural and elemental analysis of various artefacts

The applicability of an Energy Dispersive X-ray Diffractometer to some technical questions in the field of Cultural Heritage is presented. This diffractometer, equipped with a white source, has been utilized for the structural and elemental analysis of some items having different nature. Given its design, the instrument allows to collect data from samples as big as a book or a little more. Samples, without collection of any portion and without any preliminary preparation, have been placed in the instrument and spectra have been collected in a wide energy range that contains X-ray fluorescence and diffraction features. In all cases, data acquired in air and in a non destructive way were reliable and their collection was fast. Fluorescence and X-ray diffraction information, when possible, have been compared with those obtained by XRF micro-analysis and by an Angle Dispersive X-ray Diffractometer equipped with a Cu X-ray source. By using the last two techniques, data have been collected from small areas of the samples.     

Volatile Compounds of Lemon and Grapefruit IntegroPectin

An HS-SPME GC-MS analysis of the volatile compounds adsorbed at the outer surface of lemon and grapefruit pectins obtained via the hydrodynamic cavitation of industrial waste streams of lemon and grapefruit peels in water suggests important new findings en route to understanding the powerful and broad biological activity of these new pectic materials. In agreement with the ultralow degree of esterification of these pectins, the high amount of highly bioactive α-terpineol and terpinen-4-ol points to limonene (and linalool) decomposition catalyzed by residual citric acid in the citrus waste peel residue of the juice industrial production.