Application of Multispectral Imaging and Portable Spectroscopic Instruments to the Analysis of an Ancient Persian Illuminated Manuscript.

Illuminated manuscripts are, in general, the final products of a wise and complex interaction of different competencies. In particular, each manuscript reflects uses and techniques rooted in the historical and geographical traditions of the area of realization. Defining the characteristics and the materials in these valuable artefacts is an essential element to reconstruct their history and allow a more precise collocation and a possible comparison with other works in similar periods and areas. Non-invasive methods, mainly using portable instruments, offer undoubtedly good support in these studies. Recent analyses of an ancient Persian illuminated manuscript, combining multispectral imaging and spectroscopic measurements made with portable instruments (XRF, FORS, micro-Raman, IR-ATR) on selected points, provided new data for an improved understanding of this rare book. This study details the possibilities offered by combining these non-invasive methods for an in-depth understanding of the techniques and practices behind the realization of Middle Eastern illuminated manuscripts and provided new perspectives for multidisciplinary approaches to research in this field.

Photoelectrochemical Behavior of Electrophoretically Deposited Hematite Thin Films Modified with Ti(IV).

Doping hematite with different elements is a common strategy to improve the electrocatalytic activity towards the water oxidation reaction, although the exact effect of these external agents is not yet clearly understood. Using a feasible electrophoretic procedure, we prepared modified hematite films by introducing in the deposition solution Ti(IV) butoxide. Photoelectrochemical performances of all the modified electrodes were superior to the unmodified one, with a 4-fold increase in the photocurrent at 0.65 V vs. SCE in 0.1 M NaOH (pH 13.3) for the 5% Ti-modified electrode, which was the best performing electrode. Subsequent functionalization with an iron-based catalyst led, at the same potential, to a photocurrent of ca. 1.5 mA·cm(-2), one of the highest achieved with materials based on solution processing in the absence of precious elements. AFM, XPS, TEM and XANES analyses revealed the formation of different Ti(IV) oxide phases on the hematite surface, that can reduce surface state recombination and enhance hole injection through local surface field effects, as confirmed by electrochemical impedance analysis.

Microbial deterioration of artistic tiles from the façade of the Grande Albergo Ausonia & Hungaria (Venice, Italy).

The Grande Albergo Ausonia & Hungaria (Venice Lido, Italy) has an Art Nouveau polychrome ceramic coating on its façade, which was restored in 2007. Soon after the conservation treatment, many tiles of the façade decoration showed coloured alterations putatively attributed to the presence of microbial communities. To confirm the presence of the biological deposit and the stratigraphy of the Hungaria tiles, stereomicroscope, optical and environmental scanning electron microscope observations were made. The characterisation of the microbial community was performed using a PCR-DGGE approach. This study reported the first use of a culture-independent approach to identify the total community present in biodeteriorated artistic tiles. The case study examined here reveals that the coloured alterations on the tiles were mainly due to the presence of cryptoendolithic cyanobacteria. In addition, we proved that the microflora present on the tiles was generally greatly influenced by the environment of the Hungaria hotel. We found several microorganisms related to the alkaline environment, which is in the range of the tile pH, and related to the aquatic environment, the presence of the acrylic resin Paraloid B72® used during the 2007 treatment and the pollutants of the Venice lagoon.

An Experimental and Theoretical Study of the Electronic Structure of Zinc Thiophenolate-Capped Clusters.

The electronic structure of a series of thiophenolate-capped ionic/neutral clusters ([Zn(SPh)(4)](2)(-) (1); [Zn(4)(&mgr;(2)-SPh)(6)(SPh)(4)](2)(-) (2); Zn(10)(&mgr;(3)-S)(4)(&mgr;(2)-SPh)(12) (3); and [Zn(10)(&mgr;(3)-S)(4)(&mgr;(2)-SPh)(12)(SPh)(4)](4)(-) (4), Ph = phenyl), indicated as supertetrahedral fragments and possible molecular models of cubic ZnS, has been investigated by coupling density functional calculations to UV electronic and X-ray photoelectron (XP) spectroscopy. Theoretical outcomes indicate that, on passing from the tetrametallic to the decametallic clusters, there is a modification in the nature of the outermost occupied and lowermost unoccupied molecular orbitals. Actually, both in 1 and in 2 the frontier orbitals are delocalized and mainly composed of the S 3p pairs strongly mixed with the Ph pi levels (the HOMOs) and of the linear combinations of Ph pi orbitals, the LUMOs. At variance to that, in 3 and 4 both the HOMO and LUMO are highly localized, the former on &mgr;(3)-S atoms occupying C(3)(v)() coordinatively unsaturated tetrahedral positions and the latter on peripheral Zn atoms. The nature of the electronic levels involved in the UV absorption bands is discussed, and the agreement between theory and experiment is satisfactory. Neither experimental nor theoretical electronic excitation energies are influenced by the cluster size. Moreover, XPS data match quite well variations of the Zn and S gross atomic charges along the series. The different Zn-S bonding scheme characterizing terminal, &mgr;(2)-bridging, and &mgr;(3)-pyramidal S atoms allows a rationalization of the cluster behavior in solution. Along the investigated series, the only species reasonably mimicking both the structural arrangement and the electronic structure of the solid ZnS is Zn(10)(&mgr;(3)-S)(4)(&mgr;(2)-SPh)(12), which can be considered a molecular model of ZnS nonpolar surfaces.