Enzyme Production by Solid Substrate Fermentation of <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> and <Emphasis Type="Italic">Trametes versicolor</Emphasis> on Tomato Pomace

A process of solid state fermentation (SSF) on tomato pomace was developed with the white-rot fungi Pleurotus ostreatus and Trametes versicolor, using sorghum stalks as support. Operative parameters (humidity, water activity, and size of substrate particles) guaranteeing a good colonization of tomato pomace by both fungi were defined and conditions for production at high titers of the industrially relevant enzymes laccase, xylanase and protease were identified. Significant laccase activity levels (up to 36 U g⁻¹ dry matter) were achieved without any optimization of culture conditions, neither by nutrient addition nor by O₂ enrichment. Furthermore, protease activity levels up to 34,000 U g⁻¹ dry matter were achieved, being higher than those reported for the fungi typically considered as the best protease producers such as Aspergillus strains. Moreover, as one of the most significant results of this study, analysis of P. ostreatus tomato SSF samples by zymogram revealed two bands with laccase activity which had not been detected so far.     

Nondestructive analyses of carbonate rocks: applications and potentiality for museum materials

The preciousness of historical artifacts leads to the performance of nondestructive and/or microdestructive analyses, especially when the archeological finds are stored in museums. The PXRF spectrometry represents a powerful technique for the chemometric study of the materials, in alternative to the more usual destructive X‐ray‐based methods. A large set of limestones belonging to several formations cropping out in the Hyblean area (south‐eastern Sicily, Italy) was analyzed by means of a PXRF instrument. The main goal was to test the PXRF potentiality for the discrimination of rocks with similar features and to create a chemical database of carbonate rocks, which were commonly used in the past in the manufacturing of sculptures and stone artifacts. Fluorescence data were processed by means of multivariate statistical analysis. In particular, principal components analysis and linear discriminant analysis were applied. The results allowed us to classify the samples belonging to different formations and to distinguish different rock typologies within each formation. Finally, the investigation showed that the analytical PXRF data can be suitable for a substantial characterization of stone materials and this could be extended to museum materials belonging to cultural heritage. Copyright © 2012 John Wiley & Sons, Ltd.     

Conformational studies of ethylene glycol and its two methyl ether derivatives

As a theoretical analysis of the conformational equilibria of ethylene glycol, methoxyethanol and dimethoxyethane, the energy of each stable conformational isomer (rotamer) of these molecules was calculated for various temperatures and solvent dielectric constants. Classical semi-empirical potential functions were used. Besides intrinsic potentials for rotation about single bonds, intramolecular dispersion and repulsive interaction, dipole-dipole interaction and hydrogen bonding energies were included. Interaction with the solvent was considered only in terms of a continuous dielectric medium interacting with the local dipoles and quadrupoles of the molecule. For each rotamer, the dihedral angles giving the lowest energy were determined. From the energies of each rotamer, Boltzmann distributions of populations were obtained, and total concentrations were calculated in various physically distinguishable states, e.g. those with and without internal hydrogen bonds, or those in which the central C-C bond takes a trans or a gauche conformation. It is shown that the equilibrium constants, K _HB and K _TG, for these two cases are not identical. While changes in the dielectric constant may alter strongly the geometries and energies of individual rotamers, their effect on the average geometries and on the two equilibrium constants is small. The same is true of temperature changes, and is due to the presence of several rotamers in each of the physical states considered. Thus the small temperature dependence of some observed physical properties is shown to be consistent with the distribution of molecules over several conformational states. In solution, the fraction of ethylene glycol molecules with two free OH groups (i.e. without an intramolecular hydrogen bond) is predicted to be at least 20 per cent. This shows that the presence of three-dimensional hydrogen-bonded structures in the liquid, which we propose, is possible in principle.     

Characterisation and differentiation of pigments employed on the façade of “Noto’s Valley” monuments (Sicily)

Most of the “Noto’s Valley” monuments façades, located in different towns of Sicily such as Ragusa Ibla, Modica and Noto, present different colours and in many cases the towns themselves are characterized by evident chromatic variations. The knowledge of colour and in particular the characterization of pigments is of utmost importance in the baroque Sicilian buildings, because the peculiarity of the colour is one of the features that makes the “Noto Valley” monuments a World Cultural Heritage site. The present works aim is to characterise and differentiate the pigments used on the façade of monuments and inside the plasters. In particular, we perform a micro-textural and analytical analysis through scanning electron microscopy (SEM) and a mineralogical investigation through the conjunction of optical microscopy and fourier transform infrared spectroscopy (FT-IR). All the experimental results have allowed us to clearly classify the pigments into earths rich in clay minerals and earth containing gypsum. Furthermore, we also show that the earths rich in clay minerals from Ragusa and Modica areas have local provenance.     

A multi‐technique approach for the characterization of decorative stones and non‐destructive method for the discrimination of similar rocks

In this paper, a multi‐technique approach, at different scale of observation, is used to characterize a group of decorative stones and to permit to distinguish rocks with similar aspect but coming from different areas. In particular, the samples under study are sedimentary and metamorphic rocks, widely used as building blocks of modern and historical constructions and sculptures. The petrographic and mineralogical features of such rocks were performed by optical microscopy and Raman and Fourier transform infrared absorbance spectroscopies. These techniques permitted to obtain a complete structural, textural, and mineralogical characterization. At elemental level, the investigation was carried out by X‐ray fluorescence (XRF). In particular, XRF and Raman measurements were collected using portable instrumentations, whose advantages for the in situ analysis have been pointed out. The obtained results evidenced the high discriminant capability of the portable XRF for the decorative stones especially when this method is coupled with mineralogical and petrographic information. In this context, we propose to create a database for precious ornamental stones, which could be a starting point for a non‐destructive characterization, even useful for provenance study and/or certification of origin. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of the chiral and achiral related substances of methotrexate by cyclodextrin-modified micellar electrokinetic chromatography

A cyclodextrin-modified micellar electrokinetic chromatographic (CD-MEKC) method for the determination of the most important potential impurities of methotrexate (MTX): 2,4-diamino-6-(hydroxymethyl)pteridine, aminopterine hydrate, 4-[N-(2-amino-4-hydroxy-6-pteridinylmethyl)-N-methylamino] benzoic acid, 4-[N-(2,4-diamino-6-pteridinylmethyl)-N-methylamino] benzoic acid, and the distomer D-MTX is presented. The MEKC separation of these compounds was optimized by applying a step-by-step approach. The addition of beta-CD to a conventional MEKC system, based on sodium dodecyl sulfate (SDS) as surfactant, showed to be essential for the enantioresolution of racemic MTX as well as for the separation of the achiral impurities. To achieve high-resolution factor between the peaks adjacent to the main component (L-MTX), as required in the analysis of related impurities, the separation conditions were stressed; in particular, the addition of methanol to the CD-MEKC system resulted in a very effective choice. Under the optimized final conditions (100 mM SDS and 45 mM beta-CD in a mixture of 50 mM borate buffer, pH 9.30-methanol (75:25 v/v)), the method was validated showing a general adequate accuracy (93-106% recovery) in the determination of L-MTX related substances at the impurity level of 0.12% w/w with a relative standard deviation (RSD)% lower than 8% (n = 4). The method was successfully applied to the analysis of pharmaceuticals (tablets and injections) which showed to contain the distomer D-MTX as major impurity and aminopterine hydrate as a further related substance in the commercial tablets.     

Water diffusion in nanoporous glass: an NMR study at different hydration levels

By pulsed field gradient nuclear magnetic resonance measurements, we investigated the translational diffusion of water confined in the 200 A diameter pores of a sol-gel silica glass. The experiments, performed as a function of the hydration level, showed an enhancement of the self-diffusion coefficient when the water content corresponds to one or fewer monolayers. An explanation for this occurrence has been given in terms of a two-phase process involving a fast molecular exchange between the liquid and the vapor phase. Moreover, in partially filled pores, the surface water diffusion coefficient was measured, and was 4 times lower than the diffusion of liquid confined water in saturated spaces.