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The structure and growth mechanism of TiO2 ultrathin films on Cu(001) were investigated by experimental and theoretical studies. Multiple experimental techniques, including photoemission spectroscopies and scanning probe microscopy, were used to carefully characterize the chemical, electronic, and morphological structure of the metal oxide layer. A complete and flat TiO2 bilayer with a lepidocrocite-like structure is observed at the earliest stages of its growth on the Cu(001) surface under controlled experimental conditions. The employed multitechnique approach reveals that a transition between two different structures of the TiO2 film, that is, the quasi-hexagonal and lepidocrocite-like structure, occurs as a function of the coverage passing from one to two monolayers. Ab initio calculations indicate that the lepidocrocite-like structure is thermodynamically more stable on Cu(001) than the quasi-hexagonal one, thus supporting the observed transition.

The chemical, biological and physical properties of carboxymethylcellulose (CMC) hydrogels with silanized magnetite (Fe3O4) nanoparticles (NPs) as cross-linker were investigated and compared with the analogous hydrogel obtained by using 1,3-diaminopropane (DAP) as cross-linker. The magnetic hydrogel was characterized from the chemical point of view by FT-IR, whereas the morphology of the hydrogel was investigated by FESEM and STEM. The water uptake and rheological measurements reveal how much the swelling and mechanical properties change when CMC is cross-linked with silanized magnetite NPs instead of with DAP. As far as the biological properties, the hybrid hydrogel neither exerts any adverse effect nor any alteration on the cells. The magnetic hydrogels show magnetic hysteresis at 2.5 K as well as at 300 K. Magnetic measurements show that the saturation magnetization, remanent magnetization and coercive field of the NPs are not influenced significantly by the silanization treatment. The magnetic hydrogel was tested as controlled drug delivery system. The release of DOXO from the hydrogel is significantly enhanced by exposing it to an alternating magnetic field. Under our experimental conditions (2 mT and 40 kHz), no temperature increase of the hydrogel was measured, testifying that the mechanism for the enhancement of drug release under the AMF involves the twisting of the polymeric chains. A static magnetic field (0.5 T) does not influence the drug release from the hydrogel, compared with that without magnetic field.

In this study we explored the capacity of a mass spectrometry technique, ToF-SIMS, coupled with an immunological method, Dot-ELISA, to characterize the organic binders used in a 13th century painted wooden panel. The panel, which was in a poor state of conservation with only some residual painting left, was a useful bench specimen for these techniques. ToF-SIMS and Dot-ELISA results both indicated the presence of a mixture of rabbit glue and casein and rule out the use of egg in the painted layer of the samples. The results of this study show the capability of the combined use of the two methods to univocally identify protein-based binders in paintings.

In this study a multi-analytical approach was used to characterize ancient and modern constitutive materials and the stratigraphy of a Sienese wooden painting consisting of four cusps belonging to a lost Polyptych, by Andrea di Bartolo dated back to the late 14th century, repainted in the 16th century and partially restored and cleaned in the 20th century. In order to distinguish the original layers from the other ones, a comparison with the painting Adorazione dei Magi by Bartolo di Fredi (Andrea's father) dated to the 14th century, was performed. The painting Adorazione dei Magi was found to be in a very good state of conservation and provided a model of the artistic technique used in Sienese painting in the 14th century. In situ measurements by portable NMR were performed to investigate the stratigraphy of the paintings in a non-destructive and non-invasive way. By means of this technique, information about all layers constituting the paintings were obtained and used to plan the successive micro-sampling. High resolution NMR spectroscopy was applied on a few samples to characterize binders and organic substances. Specifically, solid state 13C and 31P CPMAS NMR spectroscopy and 1H NMR spectroscopy in solution were applied to characterize original and non-original materials. Other techniques such as ToF-SIMS, HPLC, IR and Raman spectroscopy were also applied.

In 1971, a complete burial of an adolescent male (Paglicci II) was found in the Evolved Gravettian layers at Grotta Paglicci (Rignano Garganico, Foggia, Southern Italy). Nearly 20 years after (1988–1989), the burial of a young woman belonging to the same cultural complex (Paglicci III) was brought to light. The re-examination of ochre and grave goods/parures from both burials provided new insights about the ritual behaviour and the technological know-how in raw material processing of the Gravettian groups. Analyses were carried out by means of 3D optical microscopy, polarized light microscopy in thin section, XRD, ICP-OES, SEM, TEM, HPLC and ToF-SIMS. Investigation was performed on a fragment of manganese oxides bearing deep incisions (discovered between the ankles of Paglicci II), which is nearly unique in the Upper Palaeolithic funerary contexts. Use-wear observations on this block suggested that it was used to obtain black pigment with different kinds of actions. Ochre materials were analysed in order to identify their nature and their processing techniques. This study was integrated with the study of a sample of natural local reddish soil and with experimental analyses carried out by grinding coarse hematites under various operative conditions. Results detected the characteristics of raw materials: a nanosized hematite-rich clayey natural material, likely technologically ready for use (Paglicci III ochre), and a mixture of a clayey–silty sand with a natural earthy-micaceous hematite (Paglicci II ochre). New inferences from the behavioural standpoint (such as the use/non-use of the grave goods, the connection between the parure shells and the sex of the dead and the hairstyling of the woman) as well as a range of possible raw material procurement sources are discussed.

In this paper, we report the results of investigations, by means of ToF-SIMS and HPLC, of samples taken from the wall painting “Madonna and Child Enthroned with Saints” (1335–1338) by Ambrogio Lorenzetti. The aim of this study was to test the capability of ToF-SIMS to identify the nature of the protein-based binders used in the wall painting. The peaks characteristic of egg components were observed in the ToF-SIMS mass spectra of the a secco -applied layers. On the contrary, the ToF-SIMS spectra of the a fresco -applied layers did not show the markers of egg. The PCA results of the protein peaks are consistent with the presence of a rabbit glue–egg mixture. The PCA of protein peaks in the ToF-SIMS spectra was carried out for artificially aged and non-aged reference samples of rabbit glue, casein, egg and their mixtures in order to estimate the effect of ageing on protein-based binding media. Both ToF-SIMS and HPLC data showed that animal glue was present in the a secco - and a fresco -applied layers. On the basis of these results, we can conclude that animal glue was not used as binding medium but was probably applied to the wall painting in prior restorations.

Substrate engineering is a key factor in the synthesis of new complex materials. The substrate surface has to be conditioned in order to minimize the energy threshold for the formation of the desired phase or to enhance the catalytic activity of the substrate. The mechanism of the substrate activity, especially of technologically relevant oxide surfaces, is poorly understood. Here we design and synthesize several distinct and stable CeO2 (001) surface reconstructions which are used to grow epitaxial films of the high-temperature superconductor YBa2Cu3O7. The film grown on the substrate having the longest, fourfold period, reconstruction exhibits a twofold increase in performance over surfaces with shorter period reconstructions. This is explained by the crossover between the nucleation site dimensions and the period of the surface reconstruction. This result opens a new avenue for catalysis mediated solid state synthesis.

In the present work we investigated the possibility of identifying proteinaceous binders, typically used in “tempera” painting, by means of ToF-SIMS and PCA method. ToF-SIMS measurements were performed on cross-sections taken from a painted wooden crucifix of the 15th century. The results of the ToF-SIMS analysis are compared with those obtained by GC–MS. ToF-SIMS measurements were carried out also on model samples simulating the layered structure of real painting cross sections to elucidate how matrix effects can influence the identification of protein based binding media. A discrimination between rabbit glue and casein on the basis of the comparison of the ToF-SIMS results for the ancient samples with those obtained from reference compounds appears to be difficult. This is mainly due to matrix effects that are relevant for these complex, multicomponent samples, as indicated by the PCA results for model painting samples of known composition. On the other hand, PCA method and the observation of characteristic fragment ions in the spectra should allow to determine the presence of egg in painting layers.

The present work was aimed at characterising the materials and assessing the state of conservation of the 'Adorazione dei Magi', a wooden panel painted by Bartolo di Fredi in the second half of fourteenth century. To this goal, innovative non-destructive investigation techniques such as portable Raman spectroscopy, visible reflectance spectroscopy and unilateral nuclear magnetic resonance, were used in situ in order to achieve surface and bulk compositional data. The former allowed the identification of the artist's palette including cinnabar, red ochre, minium, carbon black, lead white, ultramarine blue, malachite and phthalocyanine green, while the latter provided information on the stratigraphic structure and state of conservation of the wooden panel.

Ultrathin films of TiO(2) were grown on Ag(100) by evaporation of titanium in the presence of O(2) at a pressure in the 10(-4) Pa range and annealing at 770 K. The composition of the deposited films was monitored by XPS and LEIS. The morphology at the nanometric scale of the TiO(2) films and their crystallographic structure were investigated by means of STM, LEED and XPD. Above the monolayer coverage (at which the oxide film has a lepidocrocite-like structure), STM images show the formation of multilayer islands with a distribution of heights. XPD results indicate that these oxide islands have the rutile (110) structure and are epitaxially oriented with the sides of the oxide unit cell parallel to those of the substrate unit cell. The results of the DFT calculations justify the 3D growth of rutile (110) on Ag(100). The calculated strain energy required to match the metal substrate can explain the incommensurate growth of the overlayer in the direction of the long side of the oxide unit cell. The results of the calculations indicate that a commensurate growth of rutile (110) may be possible along the short side of the oxide unit cell, taking into account the relatively small strain energy to fit the lattice parameter of the substrate. The DFT calculations predict a considerable increase of the work function upon deposition of titania films on Ag(100), which can be attributed to a charge transfer from the metal to the 3d Ti empty states.

The effects on the X-ray photoelectron diffraction intensities from the substrate produced by epitaxial NiO(0 0 1) films of various thickness deposited on Ag(0 0 1) were investigated. The variations in the Ag XPD curves induced by the NiO films can be explained in terms of multiple scattering of the electrons emitted by the substrate atoms along the close-packed rows of the overlayer. Intensity minima in the XPD curves from the substrate in correspondence to intensity maxima in the XPD curves from the overlayer are observed when the thin film is commensurate with the substrate. For films of suitable thickness, the analysis of XPD curves from the substrate allows one to get information about the structure of the film and of the film–substrate interface.

An efficient strategy is employed for the preparation of magnetic hybrid hydrogels consisting of functionalized CoFe2O4 magnetic nanoparticles covalently bound to a carboxymethylcellulose (CMC) polymer. The method involves the formation of an amide bond between the carboxylic groups of CMC and the amine groups of functionalized nanoparticles, which work as the crosslinking agents of the polymer chains. The hybrid hydrogels were chemically and morphologically characterized. The rheological properties of the hydrogels were also investigated with the aim to verify their behavior under an applied mechanical stress. The hybrid hydrogel turns out to be thixotropic. Thanks to the presence of magnetic nanoparticles, the hydrogel is capable of responding to an external magnetic field. Preliminary data show the possibility of loading the hydrogel with a dye, which can be considered as a drug model, to squeeze it through a syringe and to drive the material by the application of an external magnetic field.

The reaction between Pt(3)(mu-PBu(t)(2))(3)(CO)(2)Cl (2) and ethynylferrocene, in the presence of catalytic amounts of CuI, gives Pt(3)(mu-PBu(t)(2))(3)(CO)(2)C[triple bond]CFc (1), characterized by X-ray crystallography and representing a rare example of the sigma-coordination of an alkynyl moiety to a cluster unit. In a dichloromethane (CH(2)Cl(2)) solution, compound 1 undergoes three consecutive one-electron oxidations, the first of which is assigned to the ferrocene-centered Fe(II)/Fe(III) redox couple. Spectroelectrochemistry, carried out on a solution of 1, shows the presence of a broad band in the near-IR region, growing after the electrochemical oxidation, preliminarily associated with a metal-to-metal charge transfer toward the Fe(III) ion of the ferrocenium unit. Density functional theory (DFT) has been employed to analyze the ground- and excited-state properties of 1 and 1(+), both in the gas phase and in a CH(2)Cl(2) solution. Vertical excitation energies have been computed by the B3LYP hybrid functional in the framework of the time-dependent DFT approach, and the polarizable continuum model has been used to assess the solvent effect. Our results show that taking into account the medium effects together with the choice of an appropriate molecular model is crucial to correctly reproducing the excitation spectra of such compounds. Indeed, the nature of the substituents on P atoms has been revealed to have a key role in the quality of the calculated spectra.

There exists a strong interest in developing simplified models able to predict the SnO 2 sensor response and aiming at a better comprehension of the mechanisms involved with sensing operation. In this paper, a simple grey-box model is proposed for predicting, with a good approximation (r.m.s. error 2 -based sensors in presence of oxygen and a reducing gas (CO) during fast temperature variations. Auger electron spectroscopy (AES) permitted to highlight differences in the surface composition of the sensors after extended operation time.

The structure of the interface-stabilized c(4 × 2) Ni 3 O 4 /Pd(1 0 0) monolayer has been determined by using Low Energy Electron Diffraction (LEED) I – V experiments. Tensor LEED simulations converged to a Rp factor of 0.22 with a structural model based on the NiO(1 0 0) surface, where all the atoms of the oxide phase are coplanar. In order to obtain the correct c(4 × 2) periodicity of the phase, a Ni vacancy array has been introduced into the model. In details, oxygen atoms sit on top of palladium atoms, while nickel atoms occupy the fourfold hollow sites. The lattice constant of NiO was contracted in order to match the substrate periodicity, and only a very small buckling of the Ni atoms (0.04 A) was introduced. The most relevant change with respect to a rigid NiO(1 0 0) structure is the in-plane displacement of oxygen atoms by about 0.2 A along directions almost coinciding with the 〈0 1 0〉 substrate azimuths, away from the vacant Ni site. The proposed structure is perfectly compatible with the STM images preliminarly reported in the literature.

The oxidation of the single crystal stepped Pt 3 Ti (510) surface at oxygen pressures below 10-5 mbar and at a temperature of 770 K was studied by means of X-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS) and low energy electron diffraction (LEED). Scanning tunneling microscopy (STM) was used to follow the evolution of the surface morphology on the atomic scale. The clean surface studied in ultrahigh vacuum conditions was found by LEIS to be composed of platinum only in the outermost surface plane. LEED and STM indicate that the clean Pt 3 Ti (510) surface consists of (100) terraces separated by double atomic steps. The exposure of the clean surface to oxygen at pressures in the range of 10-7–10-5 mbar leads to the growth of a titanium oxide layer (with a composition close to TiO) which covers completely the substrate surface. The TiO film has long range order and exhibits complex LEED patterns. The STM measurements indicate that the ordered array of steps is kept in the early stages of the oxide film growth, whereas a change of the step morphology and step orientation is observed during the oxidation process.

Using spot-profile analysis low-energy electron diffraction, we have studied the domain structure and morphology of the Pt3Sn(111) surface after sputtering at room temperature and subsequent anneal treatments which result in the formation of the previously reported ( 3 × 3 ) R30° and (2×2) structures. In addition, we present new results on the temperature-dependent composition of the outermost layer and the subsurface region that is obtained from quantitative analysis of low-energy ion scattering and Auger electron spectroscopy experiments. The combination of these results and previous experiments yields a detailed picture of the evolution of the surface region during the anneal treatments. Finally, we propose the existence of a phase transition at high temperatures between the (2×2) phase and a (2×2)′ phase (not previously observed) on the basis of reversible changes in the SPA–LEED, LEIS and AES data.

The structure of the oxygen-induced Rh&[;110&]; (2x2 )p2mg-O phase has been determined using low-energy electron diffraction intensity-voltage (LEED I – V ) analysis, and consists of a missing row reconstructed substrate with oxygen atoms in a zigzag arrangement. The oxygen atoms occupy the upper threefold sites on the &[;111&]; microfacets, and the nearest-neighbour bonding geometry is the same as for the (2x1) oxygen-induced low-temperature phase. In spite of the similar geometries, the reactivities of these structures for CO oxidation are very different. When the oxygen is removed from the (2x2)p2mg surface at low temperature, the substrate retains the (1x2) missing row reconstruction. LEED analysis of the (1X2) surface indicates that the first interlayer contraction is 11%, which is lower than the value determined previously by He scattering.