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Alkaptonuria (AKU), a rare genetic disorder, is characterized by the accumulation of homogentisic acid (HGA) in organs due to a deficiency in functional levels of the enzyme homogentisate 1,2-dioxygenase (HGD), required for the breakdown of HGA, because of mutations in the HGD gene. Over time, HGA accumulation causes the formation of the ochronotic pigment, a dark deposit that leads to tissue degeneration and organ malfunction. Such behaviour can be observed also in vitro for HGA solutions or HGA-containing biofluids (e.g. urine from AKU patients) upon alkalinisation, although a comparison at the molecular level between the laboratory and the physiological conditions is lacking. Indeed, independently from the conditions, such process is usually explained with the formation of 1,4-benzoquinone acetic acid (BQA) as the product of HGA chemical oxidation, mostly based on structural similarity between HGA and hydroquinone that is known to be oxidized to the corresponding para-benzoquinone. To test such correlation, a comprehensive, comparative investigation on HGA and BQA chemical behaviours was carried out by a combined approach of spectroscopic techniques (UV spectrometry, Nuclear Magnetic Resonance, Electron Paramagnetic Resonance, Dynamic Light Scattering) under acid/base titration both in solution and in biofluids. New insights on the process leading from HGA to ochronotic pigment have been obtained, spotting out the central role of radical species as intermediates not reported so far. Such evidence opens the way for molecular investigation of HGA fate in cells and tissue aiming to find new targets for Alkaptonuria therapy.

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.

Magnetic hydrogels based on carboxymethylcellulose (CMC) were prepared using magnetite (Fe 3 O 4 ) nanoparticles (NPs) functionalized with 3-aminopropyltrimethoxysilane (APTMS) as cross-linker. In this hybrid organic-inorganic hydrogel, magnetite NPs are covalently bonded to the polymer chains. The CMC-Fe 3 O 4 hydrogel was characterized by means of Attenuated Total Reflection Fourier Transform Infra Red Spectroscopy (ATR-FTIR) and Field Emission Scanning Electron Microscopy (FESEM). The equilibrium swelling degree of the CMC-Fe 3 O 4 hydrogels was measured in deionized water as well as in artificial and natural sea water. Bioassays were performed in order to assess the ecosafety of these magnetic hydrogels by testing any potential effect on the growth rate of marine microalgae Dunaliella tertiolecta . The capability of the CMC-Fe 3 O 4 hydrogel to adsorb organic and inorganic pollutants was tested on solutions of methylene blue (MB) and CdCl 2 in deionized and sea water as model systems. The CMC-Fe 3 O 4 hydrogel is capable to adsorb both MB and Cd(II) in deionized water. On the other hand, the adsorption capacity is strongly reduced in sea water, due to the ions in solution which decrease the electrostatic attraction between the carboxylate groups of CMC and the positive charge of MB and Cd(II).

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 paper we report about the preparation, physicochemical and biological characterization of a magneto responsive nanostructured material based on magnetite nanoparticles (NP) coated with hyaluronic acid (HA). A synthetic approach, based on a Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition "click" reaction between azido-functionalized magnetite NP and a derivative of hyaluronic acid bearing propargylated ferulic acid groups (HA-FA-Pg), was developed to link covalently the polymer layer to the magnetite NP. The functionalization steps of the magnetite NP and their coating with the HA-FA-Pg layer were monitored by Fourier Transform Infrared (FTIR) spectroscopy and Thermal Gravimetric Analysis (TGA) while Dynamic Light Scattering (DLS) and ζ-potential measurements were performed to characterize the aqueous dispersions of the HA-coated magnetite NP. Aggregation and sedimentation processes were investigated also by UV-visible spectroscopy and the dispersions of HA-coated magnetite NP were found significantly more stable than those of bare NP. Magnetization and zero field cooled/field cooled curves revealed that both bare and HA-coated magnetite NP are superparamagnetic at room temperature. Moreover, cytotoxicity studies showed that the coating with HA-FA-Pg significantly reduces the cytotoxicity of the magnetite NP providing the rational basis for the application of the HA-coated magnetite NP as healthcare material.

Magnetite NPs modified with CMC, a polysaccharide containing carboxylic groups derived from cellulose, were prepared. Two different methods were used: addition of CMC to a dispersion of magnetite NPs previously synthesized ( ex situ preparation) and addition of NaOH to an aqueous solution of Fe(II) and Fe(III) in the presence of CMC ( in situ preparation). The aim of this study was to characterize in detail the interactions between magnetite NPs and CMC and to elucidate the effect of the polymer on the magnetite NP agglomeration. FTIR spectroscopy was used to shed light onto the nature of the interactions between CMC and Fe 3 O 4 NPs. The morphological characterization of the NPs was carried out by FESEM. The size and the ζ-potential of the NPs in various aqueous media were determined by DLS. XRD measurements indicate that the presence of CMC does not modify, within the uncertainty of the measurement, the size of the primary particle (ca. 10 nm). FTIR spectra suggest that CMC chains are anchored to magnetite NPs via carboxylate groups interacting with iron ions at the surface. The FESEM images show that magnetite NPs prepared by the in situ method form aggregates which are significantly smaller than those prepared by the ex situ procedure. The FESEM images reveal a different morphology of the polymeric matrix between the CMC/magnetite NPs prepared following the two procedures. The hydrodynamic diameter of the CMC/magnetite NPs in water at neutral pH prepared in the presence of CMC is 280 nm. The ζ-potential (ca. −80 mV) measured for the dispersions in water at neutral pH of CMC/magnetite NPs prepared according to the two methods explains their long-term stability. The magnetic behaviour of the CMC/magnetite NPs can be explained considering the different size of the aggregates in the two kinds of sample.

In this paper the gas sensing properties of Ag–K-hollandite prepared by K–Ag ion exchange are investigated. The proposed material was used as the active layer of micromachined conductometric gas sensors and tested in different environmental conditions with a number of target gases such as CO and NOx. The response to test gases was evaluated in a temperature interval from 200 to 350 °C where surface phenomena can completely explain the sensor behavior. The proposed material was studied also by means of XPS and thermal analyses. The investigated material is a p-type semiconductor and shows a reproducible response and a complete recovery. Data obtained are discussed and a model based on surface states describing the material behavior is proposed.

Acid mine drainage (AMD) is a global environmental challenge that represents a primary source of contamination of heavy metals in both active and abandoned mining areas. The present study explored the suitability of a carboxymethylcellulose (CMC) hydrogel cross-linked with functionalized magnetite (Fe3O4) nanoparticles, (CMC-Fe3O4), for the removal of heavy metals from AMD-affected stream waters and tested its eco-friendly nature. AMD-affected stream waters, collected in a former mining site located in the Metalliferous Hills ore district (Central Italy), were chosen as a suitable benchmark for validating the CMC-Fe3O4 hydrogel applications. The remediation capability of the CMC-Fe3O4 hydrogel was investigated on solutions of Zn(II) in deionized (DI) water and on samples of AMD-affected stream waters. The CMC-Fe3O4 hydrogel was able to adsorb Zn(II) from DI water solutions as well as to reduce significantly the concentration of Zn and other heavy metals such as Cd, Co, Cu, Ni and Pb, in AMD-affected stream waters. CMC-Fe3O4 hydrogel and treated waters (both Zn-solution and AMD-affected stream waters) were tested for their effects on the freshwater green alga R. subcapitata by using 72-h growth inhibition tests. No effects were observed on the R. subcapitata growth upon exposure to CMC-Fe3O4 hydrogel, suggesting its eco-friendly nature. Moreover, CMC-Fe3O4 hydrogel was able to reduce the toxicity of heavy metals to the green alga, both in DI and AMD-affected stream water. Based on our findings, CMC-Fe3O4 hydrogel could be considered as a valuable tool for an environmentally safe treatment of AMD-affected stream waters.

The painting "Madonna with Child", attributed to Pietro Lorenzetti (14th century) and reworked around the middle of the 16th century, was studied by several techniques in order to characterize the materials used in the original and in the repainted areas. FORS, light microscopy, ESEM-EDX, ToF-SIMS and GC-MS were used. Red ochre and raw sienna earth were identified by FORS in the original parts of the painting. On the repainted parts of the panel, cinnabar, ultramarine blue and lead white were found. By means of GC-MS and ToF-SIMS measurements it was possible to identify the organic binding media used in the preparatory and painted layers. © 2013 Elsevier Masson SAS.

In this study, we investigated the physicochemical and biological properties of naked and coated titania nanoparticles. The aim of this study was to verify the effect of the biopolymer coatings (hyaluronic acid and its biphosphonated derivative) and the role of protein adsorption from a cell culture medium on the citotoxicity of nanoparticles. Infrared spectroscopy (FT-IR) was used to investigate the interactions between the nanoparticles and the polysaccharides. The ζ potentials and the average hydrodynamic diameters of naked and coated nanoparticles dispersed in deionized water, medium with and without fetal bovine serum, were measured by means of dynamic light scattering (DLS). FT-IR and DLS measurements indicate that serum proteins are adsorbed on the NPs' surface. The biological tests show that naked and coated TiO(2) NPs do not induce an acute toxic effect on fibroblast cell cultures. This result shows that protein adsorption on NPs is an important factor in explaining the effect of NPs on cellular behavior.

The surface composition of 18th century papers was investigated by means of ToF-SIMS and XPS. The aim of the present study was to explore the possibility of using these surface sensitive methods to obtain information which can help to determine the manufacturing process, provenance and state of conservation of ancient papers. The ToF-SIMS results indicate that the analyzed papers were sized by gelatin and that alum was added as hardening agent. The paper sheets produced in near geographical areas but in different paper mills exhibit a similar surface composition and morphology of the fibers as shown by the ToF-SIMS measurements. The ToF-SIMS and the XPS results indicate that a significant fraction of the cellulose fibers is not covered by the gelatin layer. This was observed for the ancient papers and for a modern handmade paper manufactured according to the old recipes.

A novel strategy is described for the preparation of polymeric hybrid hydrogels containing metal oxide nanoparticles as cross-linkers. TiO 2 nanoparticles were functionalized by introducing amine groups onto their surfaces. The functionalized metal oxide nanoparticles were covalently bound to the polymer chains of carboxymethylcellulose and appeared to be organized as clusters with dimensions of 30 nm to 250 nm within the hydrogel. This synthesis method, based on the use of functionalized nanoparticles as cross-linkers, is of general application and it allows for the preparation of other kinds of nanoparticle/polymer hybrid hydrogels. These hybrid hydrogels may have potential applications as novel in vitro scaffolds for tissue engineering, in which the inorganic nanoparticles can simulate the nanostructured architecture of the extra-cellular matrix.

Reactive deposition of Ti on the Cu(001) surface saturated with chemisorbed oxygen results in the formation of an ordered ultrathin film with a slightly distorted hexagonal (quasihexagonal) unit cell. We find that, under appropriate substrate temperature, evaporation rates, and O2 pressure, it is possible to cover the whole substrate surface with the TiO2 quasihexagonal phase. An O−Ti−O trilayer model for the (quasi) hexagonal structure is consistent with angle scanned XPD data relative to the Ti 2p signal and with the LEED I−V experimental intensity curves. From a careful inspection of the LEED pattern, we derive a distortion of the hexagonal unit cell corresponding to a p(2 × 7) coincidence mesh with the substrate. The p(2 × 7) coincidence was used to model XPD data. For the analysis of LEED-IV data and for DFT calculation, the p(2 × 7) was approximated by a c(2 × 6) coincidence mesh. The c(2 × 6) approximation is very close to a p(2 × 7) in terms of lattice parameters but contains a reduced number of n...

The growth mechanism, composition and structure of ultrathin films of titanium oxide deposited on the Cu(0 0 1) surface were investigated by means of XPS, LEIS, LEED and STM. Titanium oxide films were deposited on the Cu(0 0 1) surface previously saturated with a (√2 × 2√2) R 45° structure of chemisorbed oxygen. The oxide films were prepared by evaporation of titanium in O 2 atmosphere ( p O 2 in the 10 −6 mbar range) while the substrate temperature was kept at 573 K. The Cu LEIS signal versus the amount of deposited titanium (as determined by means of XPS) indicates the growth of 2D islands in the early stages of deposition. Upon increasing the amount of deposited titanium multilayer islands begin to grow. The XPS results indicate that the oxide phases formed for Ti coverages above 1 ML have a TiO 2 stoichiometry. At very low coverages, a LEED pattern with a centred rectangular unit cell is observed. STM measurements show that at this stage of the growth the oxide islands are incorporated in the outermost layer of the substrate and the removed copper atoms form islands around the oxide regions. The very early stages of titanium oxide growth corresponding to the formation of this rectangular phase were also investigated by Ti deposition on the oxygen chemisorbed phase under UHV conditions at 573 K. In this way it is possible to study the reaction of Ti with chemisorbed oxygen. Upon increasing the Ti coverage above 0.5 ML, an oxide film with a slightly distorted hexagonal unit cell begins to grow. The quasi-hexagonal phase of titanium oxide can also be formed by annealing at 773 K the rectangular phase. At higher coverages, when the substrate surface is completely covered by the oxide, the film exhibits a LEED pattern with a regular hexagonal unit cell.

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.

The new structural results revising commonly accepted point of view on role of products of silver chlorination in catalytic reaction of ethylene epoxidation are presented. It was established that AgCl nucleation on Ag(111) mainly occurs on step edges but low temperature reaction could also start on atomic terraces. On atomically resolved images of AgCl nuclei surface obtained with scanning tunneling microscope, the specific features of atomic size were observed and attributed to silver atoms and atomic clusters. We predict that such silver cluster formation could explain a very high activity of chlorinated surface in ethylene epoxidation. Interatomic distances measured in thin AgCl films were found to be equal to corresponding bulk parameters. The photoelectron diffraction patterns observed upon Ag(100) chlorination were explained by the formation of AgCl(111) domains rotated on 90° with respect to each other.

The alloying process of Ti deposited on Cu(0 0 1) was studied by means of XPS, LEIS, XPD and LEED intensity analysis. With the sample held at 570 K, a linear decrease of the Cu LEIS signal as a function of the amount of Ti deposited is observed in the early stages of deposition until a constant value is reached. At the onset of the plateau a c(√2 × 5√2)R45° LEED pattern starts to be visible. XPD and LEED intensity measurements were performed for the c(√2 × 5√2)R45° phase prepared depositing ca. 1.5 monolayer of Ti. The angle-scanned XPD curves measured for the phase c(√2 × 5√2)R45° reveal that Ti atoms substitute Cu atoms in the fcc lattice of the substrate. The polar XPD curves show that at least the first four layers of the substrate are involved in the alloying process. We found that the (3 1 0) plane of the Cu 4 Ti alloy (D1 a type-structure) fits, without significant contraction or expansion of the lattice parameters, the c(√2 × 5√2)R45° structure. The intensity versus energy curves of the diffracted beams were calculated on the basis of this structural model using the tensor LEED method. The results of the LEED intensity analysis provide a further evidence of the formation of a slab of Cu 4 Ti(3 1 0) layers.

Submonolayers of nickel oxide were grown on the Ag(001) surface by evaporation of Ni in the presence of O2 at a pressure of 1 ? 10?6?mbar. In the early stages of deposition, two-dimensional oxide islands with a (2 ? 1) periodicity grow on Ag(001). After annealing at about 500?K, the (2 ? 1) single atomic layer transforms into NiO(001) double layer islands. The 1:1 stoichiometry of the film is not influenced by whether the annealing is carried out in vacuum or in the presence of oxygen. However, the oxide islands exhibit different morphologies depending on the O2 pressure during the annealing process.

The initial growth stages of nickel deposited on Ag(0 0 1) have been investigated by LEIS, XPS, STM and XPD. Embedded atom method (EAM) calculations were performed to obtain information about the dynamics of Ni adatoms on the Ag(0 0 1) surface. Amounts of Ni ranging from submonolayers up to 4 monolayers were deposited on the Ag(0 0 1) surface under UHV conditions at room temperature. The LEIS spectra indicate that the Ni islands are almost completely covered by silver. In agreement with previous studies, STM images show that Ni grows on Ag(0 0 1) forming three dimensional islands. A significant fraction of islands with a thickness of 2–3 atomic layers is present even at coverages as low as 0.1 ML. The observation of islands protruding from the surface with heights below that expected for one atomic layer of Ni covered by one atomic layer of Ag suggests that Ni atoms are incorporated in the outermost layer of the substrate. From the EAM calculations the energy barrier for incorporation of a nickel atom into the outermost layer was found to be 0.19 eV, substantially lower than that for bridge site hopping over the substrate (0.61 eV). On the basis of the EAM calculations, a diffusion mechanism for Ni atoms incorporated within the first layer of the surface is proposed to explain the growth of Ni islands. As far as the geometric structure of the Ni film is concerned, the XPD curves indicate that at a coverage of ≈0.3 ML, the structure of the film is distorted with respect to the fcc lattice. The displacement of the forward scattering peaks towards higher polar angles is consistent with the formation of pseudomorphic Ni islands (i.e. with the same in-plane lattice parameter of the substrate). The XPD results lead to the conclusion that pseudomorphic Ni clusters coexist with undistorted fcc Ni islands. Even at the highest coverage studied here, a fraction of the islands maintains a strained fcc structure.

Ultrathin nickel oxide films were grown on the Ag(001) surface by evaporation of Ni in an O 2 atmosphere. The growth mechanism, composition, and structure of the NiO layers formed in the early stages of deposition have been investigated by LEIS, XPS, XPD, and LEED. We found that at O 2 pressures in the 10 - 7 - 10 - 6 mbar range and sample temperatures between room temperature and 373 K, a nickel oxide layer forms showing a (2 × 1) LEED pattern. This is a phase of monatomic thickness which gradually covers the substrate surface upon increasing the surface coverage. LEIS and XPS data show that before the (2 × 1) layer is completed NiO(001) islands start to nucleate. The substrate surface is completely covered by NiO(001) for coverages higher than 2 ML. When NiO is deposited with the sample held at 453 K, we found that in the early stages of deposition metallic Ni is present in the subsurface region of the substrate. Upon further NiO deposition the oxide becomes the prevalent species on the surface. Under these conditions, the (2 × 1) phase is not observed. We found that the (2 x 1) phase is not stable upon annealing at 473-600 K and transforms into NiO(001). LEIS and XPD results indicate the formation of NiO islands 2 ML thick upon annealing. The structure of the (2 × 1) phase has been investigated by LEED intensity analysis (tensor LEED method). The best agreement with the experimental data is obtained for a structural model similar to the (111) surface of NiO. The effects of surface temperature and O 2 pressure on nickel oxide growth are discussed in terms of the low sticking probability of O 2 on Ag(001) and of the interaction between nickel and silver.

We investigate the Ir(1 1 0)-c(2 × 4)S adsorbate system using X-ray photoelectron diffraction. As proposed by a previous structure model based on a scanning tunneling microscopy experiment, we find that sulfur atoms of this superstructure enter the second adsorption layer. In contrast to the existing structure model the adatoms do not occupy on-top adsorption sites above first-layer adatoms. We refine the proposed structure model by moving sulfur atoms of the second adsorption layer out of the on-top position. Our experimental results are compared with single and multiple scattering calculations.

The structure of a nickel oxide film 2 ML thick has been investigated by LEED intensity analysis. The NiO film was prepared by evaporating Ni in presence of O2 at a pressure in the 10 � 6 mbar range. The growth of the oxide film was followed by XPS,LEIS and LEED. In the early stages of deposition,the film shows a (2 � 1) superstructure in LEED. After deposition of 2 ML of NiO,a sharp (1 � 1) LEED pattern is observed. The intensity versus electron energy curves of the LEED spots were measured for this NiO(1 � 1) film and analysed by means of the tensor LEED method. A good level of agreement of the experimental LEED intensities with those calculated for a pseudomorphic NiO(0 0 1) film was obtained. We found that oxygen atoms at the oxide–substrate interface are on-top silver atoms. The interlayer distance in the oxide does not differ significantly from that in bulk NiO(0 0 1),within the accuracy of the analysis. An outward displacement (0.05 � 0.05 � of oxygen atoms with respect to nickel atoms was found at the oxide film surface. The interlayer distance at the silver–nickel oxide interface is 2.43 � 0.05 � 2003 Elsevier Science B.V. All rights reserved.

Exposure of the Pt3Sn(1 1 1) surface to oxygen at a pressure in the 10 � 6 mbar range at 800 K leads to the formation of a chemisorbed phase with a (4 � 4) periodicity. In previous works we investigated the structure of the (4 � 4) phase by means of scanning tunneling microscopy (STM) and XPD. STM images show that the (4 � 4) periodicity results from an array of protrusions and holes. XPD data suggest that oxygen adsorption induces the reconstruction of the substrate with the formation of a Sn–O overlayer. In the present work, several structural models compatible with the STM and XPD results were tested by tensor LEED analysis. The best agreement with the experimental I–V curves was obtained for a model similar to that proposed to interpret the STM images of the Ag(1 1 1)(4 � 4)–O phase. According to this structure, the protrusions observed in STM would correspond to tin atoms occupying on-top positions. 2002 Elsevier Science B.V. All rights reserved.

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.

Bronze samples with a composition analogue to that of the Renaissance statuary were artificially aged in a climatic chamber with moist air containing sulphur dioxide at ppm levels. The corrosion patinas formed on the surface of the samples were investigated by means of X-ray photoelectron spectroscopy (XPS). After almost 1 month of exposure, the XPS spectra showed only the presence of copper hydroxysulphates and carbonates. A depth-profile analysis was performed by combining ion etching and XPS. The XPS spectra measured after Ar ion bombardment showed the presence of sulphides besides the peaks due to copper sulphate and sulphite. Test experiments performed under the same conditions on copper sulphate samples clearly show that CuSO 4 decomposes under ion bombardment with the formation of copper sulphides. Therefore, the observation of sulphide in the depth-profile analysis of the corrosion layers cannot be taken as an evidence of the existence of copper sulphides buried under the copper sulphate layers.

Ultrathin layers of vanadium oxides on SnO 2 (1 1 0) were prepared by evaporation of metallic vanadium in oxygen atmosphere (partial pressure of O 2 : 1×10 −5 Pa) at room temperature (RT). Vanadium oxide layers were deposited on the (4×1) reconstructed surface of SnO 2 (1 1 0). The substrate surface was prepared by cycles of sputtering and annealing in vacuum. X-ray photoelectron spectroscopy (XPS) and low-energy ion scattering (LEIS) results show that the growth mechanism of the oxide layers involves the migration of tin atoms from the substrate onto the surface of the film already at RT. Although no LEED pattern is observed, the X-ray photoelectron diffraction (XPD) measurements reveal that the vanadium oxide films grow epitaxially on the substrate surface. The similarity between the Sn 3d XPD pattern measured for the clean SnO 2 (1 1 0) surface and the V 2p pattern measured for the oxide layers suggests that these films have a structure close to that of the substrate (rutile-type lattice). The present results can be explained with a formation of a vanadium oxide of the series V n O 2 n −1 with 4⩽ n ⩽8. These so called Magneli phases of vanadium oxides have structures similar to that of rutile VO 2 . This interpretation was confirmed by comparison of multiple scattering calculations with the experimental XPD curves. The vanadium oxide films are stable and the formation of mixed vanadium–tin oxide does not occur after annealing in vacuum at ≈800 K. The XPD data seem to indicate that tin atoms are present at the surface as a two-dimensional phase. STM images collected for the annealed phases reveal a morphology consistent with the XPS and LEIS results.

Polysaccharide-based hydrogels are very promising materials for a wide range of medical applications, ranging from tissue engineering to controlled drug delivery for local therapy. The most interesting property of this class of materials is the ability to be injected without any alteration of their chemical, mechanical and biological properties, by taking advantage of their thixotropic behavior. It is possible to modulate the rheological and chemical-physical properties of polysaccharide hydrogels by varying the cross-linking agents and exploiting their thixotropic behavior. We present here an overview of our synthetic strategies and applications of innovative polysaccharide-based hydrogels: hyaluronan-based hydrogel and new derivatives of carboxymethylcellulose have been used as matrices in the field of tissue engineering; while guar gum-based hydrogel and hybrid magnetic hydrogels, have been used as promising systems for targeted controlled drug release. Moreover, a new class of materials, interpenetrating hydrogels (IPH), have been obtained by mixing various native thixotropic hydrogels.

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.

The composition of the (1 1 0) surface of the Fe–Ni 34 at.% alloy has been determined by means of low-energy ion scattering (LEIS). Since the masses of the iron and nickel nuclides are rather close, a curve fitting procedure was needed to determine the contribution of the two metals to the LEIS signal. The LEIS measurements have been performed in a temperature range between room temperature and 850 K. Shadow cone effects were exploited, measuring the LEIS spectra with the ion beam incident along appropriate azimuthal direction, in order to determine the composition of the topmost layer only. We found that the surface concentration of nickel increases for increasing temperatures. At 850 K the composition of the topmost layer is 41±2 at.% of Ni.

The (4×1) reconstruction of the SnO 2 (1 1 0) surface has been determined by means of low energy electron diffraction (LEED) intensity analysis. The (4×1) reconstruction was obtained by annealing at 1000 K the ion bombarded SnO 2 (1 1 0) surface. The intensity versus accelerating voltage ( I – V ) curves measured for this surface were compared with calculations performed using the tensor LEED method. As a reference structure, we used the model proposed on the basis of the STM images obtained for the SnO 2 (1 1 0)(4×1) superstructure. This model consists of an ordered array of oxygen vacancies in the topmost mixed oxygen–tin layer. The results of the present analysis confirm the STM model. Moreover, we found a buckling in the first layer and lateral displacements of the atoms with respect to the ideal positions around the oxygen vacancies.

Electrochemical Atomic Layer Epitaxy (ECALE) was used to obtain multi-atomic layers of CdS on a single crystal Ag(111) substrate. Electrochemical stripping measurements indicate that the amount of Cd and S in these films corresponds to the stoichiometric 1:1 ratio. This result was confirmed by X-ray photoelectron spectroscopy (XPS). Measurements performed by X-ray photoelectron diffraction (XPD) permitted the determination of the structure and orientation of the CdS phase. This structure turned out to be the wurtzite lattice with the (0001) plane parallel to the substrate plane and a Cd type termination.

The aim of this study is to obtain data useful to elucidate the sensing mechanism of solid state microsensors for hydrocarbon detection based on mixed vanadium/tin oxides. The sensors studied here were prepared by deposition of an active layer of Sn and V oxides on pre-oxidized porous silicon. The surface composition of these sensors was studied by a combination of low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS). Parallel studies were performed on a ‘model’ system prepared by depositing a thin film of vanadium on a single crystal SnO2(1 1 0) surface and by successive thermal treatment. The results obtained show that vanadium is detectable by LEIS in the topmost atomic layer of both the polycrystalline and the s.c. sample in similar amounts. On the model system, the results of X-ray photoelectron diffraction (XPD) measurements show the formation of epitaxial VO2. The main conclusions of the present study are that in these sensors vanadium and tin oxide form separate phases and that vanadium species are present in the outermost surface. Both phases may take an active part in the mechanism of hydrocarbon detection in these sensors.

The growth mechanism of vanadium films deposited on the SnO2(110) surface at room temperature and the structure of the phases formed after annealing at 800 K were studied using X-ray photoelectron ...

The oxide phases formed upon annealing at 800 K of ultrathin vanadium films deposited on the SnO 2(110) surface have been investigated by XPD and other techniques. We found that the annealing in vacuum of vanadium layers results in the oxidation of the metal carried out by lattice oxygen diffusing from the bulk of SnO 2. The vanadium oxide phase formed in this way is epitaxially oriented with respect to the substrate and is covered by disordered layers of tin oxide. The XPD results rule out the formation of V–Sn mixed oxides. The simulation of the experimental XPD curves with SSC calculations performed for various structural models indicates that the product of the oxidation is a VO x ≈ 2 phase with a structure close to that of the rutile VO 2(110) surface.

The (001) surface of a Au 3 Pd single crystal was studied with different surface analytical techniques. The main results reported about structure, composition and dynamics of the surface are based on ion scattering methods and LEED. We find segregation of Au to the surface forming a complete Au overlayer. The second layer has approximately the bulk Pd concentration. There is no evidence for chemical order in the near surface layers, i.e. Pd is randomly distributed in the lattice. The Au and Pd atoms in the first and the second layer respectively have approximately the same thermal vibrational amplitudes.

The (110) surface of the alloy ${\mathrm{Au}}_{3}\mathrm{Pd}$ has been investigated by quantitative low-energy electron diffraction and low-energy ion scattering spectroscopy to determine the structure and composition of the first three atomic layers. The structure and the segregation profile have also been modeled by means of the embedded atom method, combined with Monte Carlo simulations. Both the experimental and theoretical results indicate segregation of gold, resulting in (nearly) pure Au in the two topmost layers. The surface is $(1\ifmmode\times\else\texttimes\fi{}2)$ missing-row reconstructed similarly to Au(110), with a significant contraction of the first interlayer spacing and a buckling in the third layer.

The structure of ultrathin films of Ni deposited at room temperature on the Pt (111) surface has been determined by low energy electron diffraction (LEED) intensity analysis. The first monolayer of Ni grows pseudomorphically on Pt (111) despite the 11% mismatch between the lattice parameters of nickel and platinum. The results of the analysis also show that the Ni atoms occupy face-centered-cubic sites on the substrate surface. These results in part confirm previous data obtained by X-ray photoelectron diffraction, but also provide more reliable data on the site assignment.

Layers of silver chloride were formed by exposing the Ag(100) surface to gaseous chlorine at 250 K. The growth and structure of the AgCl layers have been characterized by XPD, LEIS and LEED. The formation of AgCl was monitored by looking at the line shape and position of the Ag M 4,5 VV transitions. The chlorination process was also followed by LEIS. The XPD data, collected keeping the sample at 150 K, indicate that AgCl layers ca. 20 A thick grow with the (111) plane parallel to the substrate surface but randomly oriented with respect to the Ag(100) surface. Instead, the XPD patterns show that thicker AgCl films grow epitaxially on Ag(100).

A single-crystal FeSi(100) sample has been studied by means of X-ray photoelectron diffraction (XPD) and low-energy ion scattering (LEIS) in order to investigate the structure and the composition of the outermost atomic layers. XPD intensity plots for the Fe 2p and Si 2s core levels were acquired, and the experimental results were compared with theoretical calculations. Good agreement was found for the bulk-like surface model. The LEIS results indicate that the surface is silicon-terminated.