BACKGROUND AND METHODS:Several standard powdered black pigments were characterized by means of thermogravimetry TG-DTG and allied techniques. These pigments were used to make standard plaster frescoes at this purpose prepared. The latter ones were subjected to Raman and reflectance analysis. The results obtained, together with TG data, were chemometrically processed and used to identify an analogous standard fresco fabricated by an unknown commercial black pigment, obtaining excellent results.RESULTS:The same colorimetric and reflectometric techniques, coupled with suitable chemometric techniques, were then successfully used to identify the type of black pigment present in an ancient roman fresco of the Imperial Age (30 B.C.).CONCLUSION:TG-DTG resulted useful techniques to autenticate powdered black pigments.Colorimetry and Raman, but also the only colorimetry, were useful to identify an ancient black pigment in situ.

Temperature responsive copolymers of dextran grafted with poly(N-isopropylacrylamide) (Dex-g-PNIPAAM) were prepared by atom transfer radical polymerization (ATRP) in homogeneous mild conditions without using protecting group chemistry. Dextran macroinitiator was synthesized by reaction of dextran with 2-chloropropionyl chloride at room temperature in DMF containing 2% LiCl. ATRP was carried out in DMF:water 50:50 (v/v) mixtures at room temperature with CuBr/Tris(2-dimethylaminoethyl)amine (Me6TREN) as catalyst. Several grafted copolymers with well defined number and length of low polydispersity grafted chains were prepared. Temperature induced association properties in aqueous solution were studied as a function of temperature and polymer concentration by dynamic light scattering, fluorescence spectroscopy and atomic force microscopy (AFM). LCST, ranging from 35 to 41°C, was significantly affected by number and length of grafted chains. The fine tuning of LCST around body temperature is an important characteristic not obtainable by conventional radical grafting of PNIPAAM. Well defined spherical nanoparticles were formed above the LCST of PNIPAAM. Hydrodynamic diameter was in the range 73–98nm.

Atomic Force Microscopy was used on pure cotton cellulose paper to characterize the relationship between surface topographies and cellulose degradation patterns. Whatman N.1 chromatography paper and Fabriano Umbria paper artificially aged with different procedures and then naturally aged‐were evaluated together with a sample from an original book. Evidence is found of a clear distinction between surface heights distribution of chiefly oxidised samples with respect to those where hydrolysis is the dominant process. In both cases, deteriorated paper shows surface features well different from the paper in good preservation state, in agreement to results from previous experiments. This is a first step that could open the way to AFM application as a qualitative diagnostic tool for library materials. The only way to achieve such a goal is to extend the experimentation to a wider population of paper samples, so to improve the statistical evaluation. Copyright © 2008 John Wiley & Sons, Ltd.

The degradation of CsI thin film photocathodes (PCs) under UltraViolet (UV) irradiation has been investigated by measuring the photocurrent as well as the absolute Quantum Efficiency (QE) as a function of the accumulated charge density.Atomic Force Microscopy (AFM) and UV Photoemission Electron Microscopy (PEEM) have been employed to study the surface morphology and the local QE of polycrystalline CsI thin films and their transformation due to UV irradiation.The photoemissive properties of CsI PCs, together with their surface morphology, have been found to be strongly affected by the UV photon ageing. (c) 2007 Elsevier B.V. All rights reserved.

Spatial, energy, and time-dependent effects induced by surface charging of conductive and nonconductive samples have been studied by spectroscopic and microscopic techniques. Surface charging of indium-tin oxide and cesium iodide has been studied by atomic force microscopy with a conducting tip and photoemission electron microscopy. Intensity fluctuations of the photoemission spectra recorded on amorphous and crystalline silicon nitride are also presented. The consequence of such effects on the determination of local physical and chemical properties of insulating materials is discussed.

Three distinct wet chemistry recipes were applied to hydrogen-terminated n- and p-Si(100) surfaces in a comparative study of the covalent grafting of two differently substituted 2,2'-bipyridines. The applied reactions require the use of heat, or visible light under a controlled atmosphere, or a suitable potential in an electrochemical cell. In this last case, hydrogen-terminated silicon is the working electrode in a cathodic electrografting (CEG) reaction, in which it is kept under reduction conditions. The resulting Si--C bound hybrids were characterized by a combination of AFM, dynamic contact-angle, and XPS analysis, with the help of theoretical calculations. The three distinct approaches were found to be suitable for obtaining ligand-functionalized Si surfaces. CEG resulted in the most satisfactory anchoring procedure, because of its better correlation between high coverage and preservation of the Si surface from both oxidation and contamination. The corresponding Si-bipyridine hybrid was reacted in a solution of CH3CN containing CuI ions coordinatively bound to the anchored ligands, as evidenced from the XPS binding-energy shift of the N atom donor functions. The reaction gave a 1:2 Cu-bipyridine surface complex, in which two ligands couple to a single CuI ion. The surface complex was characterized by the Cu Auger parameter and Cu/N XPS atomic-ratio values coincident with those for pure, unsupported CuI complex with the same 2,2'-bipyridine. Further support for such a specific metal-ligand interaction at the functionalized Si surface came from the distinct values of Cu2p binding energy and the Cu Auger parameter, which were obtained for the species resulting from CuI ion uptake on hydrogen-terminated Si(100).

The present study demonstrates that H(2)O(2) and OH(.-) cause fibril aggregation and catalytic inactivation of porcine fumarase. In the aggregated (oxidized) enzyme, modifications in both secondary and tertiary protein structure occur and the enzyme aggregation obeys to fractal geometry. We then collected information on the fractal dimension and on the size and shape of fumarase aggregates by using Synchrotron Radiation (SR) Small Angle X-ray Scattering (SAXS) analysis. The geometrical self-similarity assessment of aggregates has been revealed by both AFM and SEM measurements at different scale of magnification. Micrographs collected remarkably demonstrate that the oxidized enzyme shows dendritic fractal structure over a large range of sizes.

In this study AFM technique has been used to observe the degradation of cellulose fibres in paper samples used as substrata for the growth of a filamentous fungus known to be responsible for damage to art works made from or supported on paper. images obtained from the analysis of artificially deteriorated samples have been used for comparison with topographies obtained by AFM from naturally affected samples. As '' control '' images, AFM topographies of samples obtained from the same paper quality utilised as substrata for fungal inoculum were considered. The samples that were artificially deteriorated and those naturally affected by biological agents showed, at the molecular level, distinct surface differences when compared with control images. The biodegradation of cellulose fibres that appeared in AFM images can be attributed to the activity of both cellulolytic enzymes and acidic compounds produced by the fungal cells. Further studies using the AFM technique could reveal interesting aspects of paper biodeterioration caused by different microrganisms and might allow for a better description of the different stages of fungal attacks on cellulose fibres.

A reversible electrochemical behavior is demonstrated on a specially prepared redox-functionalized H-Si(100) surface, obtained via an extra-mild grafting procedure from vinylferrocene. The results of a detailed XPS and electrochemical characterization of the resulting hybrid are reported and discussed to propose it as a reference system for high-quality electroactive monolayers on Si. The investigated ferrocene derivative bears a functional group suitable for a mild route to covalent anchoring on Si, which is based on a photoinduced reaction with visible light under an inert atmosphere. Electrochemical reversibility is shown by sharp symmetric voltammograms on freshly prepared p-Si electrodes. Anodic oxide growth is responsible for the progressive degradation of the electrochemical response. Still, fast electron transfer to the surface redox species is maintained during several thousands cycles.

Background: It is common knowledge that static magnetic fields (SMF) do not interact with living cells; thus, fewer studies of SMF compared with variable magnetic fields are carried out. However, evidence demonstrated that SMF affect cellular structures. To investigate the effect of exposure to increasing doses of SMF on cell morphology, human glioblastoma cells were exposed to SMF ranging between 80 and 3,000 G (8 and 300 mT).Methods: Cell morphology of human glioblastoma cells, derived from a primary culture, was studied by electron and optic microscopy. FITC-phalloidin staining of actin filaments was also investigated. Finally, cell surface structure changes were detected by atomic force microscopyResults: Scanning electron microscopy demonstrated a dose-dependent cell shape modification, progressive cell detachment, loss of the long villi, and appearance of membrane toughness and blebs. FITC-phalloidin staining confirmed the villi retention and cell dimension decrease. At 3,000 G, the appearance of apoptotic morphology was also observed by transmission electron microscopy cell exposed to SMF showed different orientation and alignment when compared with nonexposed cells. The atomic force microscopy of the exposed cells' membrane surfaces demonstrated the disappearance of the ordered Surface ripples and furrows typical of the unexposed cells, and the occurrence of surface membrane corrugation at increasing dose exposureConclusions: Our experimental procedures demonstrated that exposure to SMF affects not only cell size, shape, and orientation but also human glioblastoma cells' membrane surfaces. (C) 2006 international Society for Analytical Cytology.

Scientific approach to cultural heritage conservation is very important for cultural reasons and also in order to avoid mistakes in restoration work. Acidity and oxidation play a very important role in paper conservation. Deacidification is a widely used method to remove acidity on aged papers, but if a large amount of carbonyl groups is present in the paper, a strong deacidification can promote an alkali-catalysed beta-alkoxy elimination, leading to the breaking of the anhydroglucose ring in the cellulose chain.In this case, and also in the case of non-acidic but oxidised papers, a reduction treatment is necessary. Because of the high costs of restoration procedures, it is essential to determine whether the reduction treatment is a primary need.In this work we report a study, based on micron-scale space resolved Raman microscopy, infrared reflectance spectroscopy and atomic force microscopy, of differently degraded samples of paper.Non-treated and oxidised samples were investigated, as well as original ancient documents.The aim of this work is to achieve a better understanding of the degradation pattern of historical samples in order to be able to choose the most appropriate restoration treatment using non-destructive spectroscopic techniques.Analysis of the samples demonstrates that degradation processes occur mainly on fibrils and on the fibre wall, as shown also by atomic force microscopy measurements. Copyright (C) 2006 John Wiley & Sons, Ltd.

Atomic Force Microscopy (AFM) has been used to study fiber degradations, as they appear on paper surface, aiming -in the mid term- at assessment of a micro-destructive technique capable of providing qualitative and semi-quantitative information on deterioration and ageing. AFM topographies of pure cellulose paper samples artificially aged were considered as well as topographies of original paper samples naturally aged showing different kind of deterioration. Whatman N.1 chromatography paper was used as a model system to study ageing effect on sub-micron structures on cellulose fibers. Chemical and biological deterioration processes were modeled, as well, by mean of artificial degradation treatments, following the criteria of reproducing effects frequently isolated from library materials. The effects of chemical reaction induced by accelerated ageing in climatic chamber (80°C, R.H. 65%) on paper surface, and the effects of a fungal attack reproduced in vitro inoculating paper samples with Aspergillus terreus Thom (6000spores/100μl, 27°C, R.H. 100%) were evaluated by means of Atomic Force Microscopy imaging, and spectrophotometric measurement in the UV-Vis-NIR. In order to map structure local properties, morphological variations repeated with statistical relevance were correlated to chemical, biological and spectroscopic characterization. Information achieved from such analysis is then used for a comparison with measurements of naturally aged paper, providing insight in analysis and classification of typical phenomena, like yellowing and foxing stains, usually affecting valuables in libraries.

Atomic force microscopy was used to characterize the effects of chemical reactions induced by accelerated ageing in a climatic chamber (80°C, R.H. 65%) on Whatman no. 1 chromatography paper surface, in order to study ageing consequences on sub-micron structures in cellulose. Evaluation was carried out by means of a comparison of topographic data with chemical characterization, in addition to spectrophotometric measurement in the UV–vis–NIR range. Imaging of samples at several treatment stages showed a non-homogeneous decomposition of the fibre surface into fibril bunches. Over paper sheet surfaces, occurrence of this phenomenon increases with ageing. Spectrophotometry measurements showed a strong variation of contributions in the UV–vis bands, both in the yellow chromophores region and in the carbonyl formation region, which was consistent with the hypothesis that a predominant oxidation mechanism is involved.

Light-assisted surface anchoring to H-terminated n- and p-Si(100) wafers has resulted in the production of molecular electroactive monolayers from Si–C bound vinylferrocene (VFC). The resulting hybrids have been characterized by means of X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and electrochemically. White-light photoactivated anchoring has resulted in a mild route. The functionalized Si surface results negligibly oxidized, and the C/Fe atomic ratio is close to the value for the precursor. Electrochemical methods have been applied to investigate the role played by a covalent Si–C anchoring mode towards substrate–molecule electronic communication, a crucial issue for future molecular electronics devices. The response from cyclic voltammograms (cv's) for p-Si(100) functionalized electrodes, run in the dark and under illumination, has shown that the electron transfer is not limited by the number of charge carriers, confirming the occurrence of electron transfer via the Si valence band. The hybrids have shown a noticeable electrochemical stability and reversibility under cyclic voltammetry, and the trend in peak current intensity vs. the scan rate was linear. The molecule–Si bond is preserved for thousands voltammetric cycles, although both the coverage, evaluated from cv and XPS, and the electron transfer rate constant decrease with electrode ageing. VFC/p-Si resulted in the best-to-date large-area charge storage hybrid device responding to AC with no dissipation up to 100 Hz.

Molecular electroactive monolayers have been produced from vinylferrocene (VFC) via light-assisted surface anchoring to H-terminated n- and p-Si(1 0 0) wafers prepared via wet chemistry, in a controlled atmosphere. The resulting Si–C bound hybrids have been characterized by means of XPS and AFM. Their performance as semiconductor functionalized electrodes and their surface composition have been followed by combining electrochemical and XPS measurements on the same samples, before and after use in an electrochemical cell. White-light photoactivated anchoring at short (1 h) exposure times has resulted in a mild route, with a very limited impact on the initial quality of the silicon substrate. In fact, the functionalized Si surface results negligibly oxidized, and the C/Fe atomic ratio is close to the value expected for the pure molecular species. The VFC/Si hybrids can be described as (η5-C5H5)Fe2+(η5-C5H4)–CH2–CH2–Si species, on the basis of XPS results. Electrochemical methods have been applied in order to investigate the role played by a robust, covalent Si–C anchoring mode towards substrate-molecule electronic communication, a crucial issue for a perspective development of molecular electronics devices. The response found from cyclic voltammograms for p-Si(1 0 0) functionalized electrodes, run in the dark and under illumination, has shown that the electron transfer is not limited by the number of charge carriers, confirming the occurrence of electron transfer via the Si valence band. The hybrids have shown a noticeable electrochemical stability and reversibility under cyclic voltammetry (cv), and the trend in peak current intensity vs. the scan rate was linear. The molecule-Si bond is preserved even after thousands of voltammetric cycles, although the surface coverage, evaluated from cv and XPS, decreases in the same sequence. An increasingly larger surface concentration of Fe3+ at the expenses of Fe2+ redox centers has been found at increasing number of cv's, experimentally associated with the growth of silicon oxide. Surface SiO− groups from deprotonated silanol termination, induced by the electrochemical treatments, are proposed as the associated counterions for the Fe3+ species. They could be responsible for the observed decrease in the electron transfer rate constant with electrode ageing.

The chemical reactions and diffusion processes at the interface of a metal with oxides and nitrides are a critical issue in the production of metal–dielectric optical filters. The optical properties of these filters depend on the quality of the interfaces between the metal layer and the adjacent dielectric layers. The chemical and physical processes occurring at the silver–dielectric interface are studied by means of ellipsometry and XPS analysis and comprise the subject of the present work.

A variation of the neural algorithm locally excitatory globally inhibitory network has been developed for automatic recognition, count, and morphological analysis of a large number of quantum dots. In a typical image of 256×256 pixels (500×500 nm2), the program recognizes the dots with an average error of about 3%. It also calculates area and height of each of them. Furthermore, the recognition procedure is very fast (less than 2–3 s on a Pentium III at 600 MHz).

Ageing effects on aerogel due to irradiation and absorption of humidity have been investigated. Aerogel tiles have been exposed to γ radiation from a 60Co source and to proton and neutron high intensity beams. The transmittance has been monitored in the wavelength range between 200 and 800nm, determining the clarity factor C as a function of the increasing dose of irradiation. The index of refraction n was also measured.

The surface of a Li-insertion In–V mixed-oxide electrode and the evolution of its composition and morphology upon prolonged intercalation/deintercalation cycles have been studied by a combination of the following bulk and surface-sensitive analytical techniques: Electrochemical analysis (cyclic voltammetry, impedance spectroscopy), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and scanning photoelectron spectromicroscopy (SPEM). The In–V oxide film, obtained by rf sputtering as a thin film on conductive glass for use as a transparent electrode in electrochromic windows, is a Li-insertion material with good reversibility and high charge capacity, having a surface morphology characterised by a low initial roughness. XPS results showed that Li+-insertion brought about the reduction of V5+ to V4+ and V3+, with the onset of new structures in the valence band, related to the formation of Li2CO3 on the electrode surface. Such chemical changes were largely reversed upon Li-deinsertion and only a barely detectable effect on the surface morphology was seen after up to ten cycles. Extensive Li-charge–discharge cycling induced larger changes in the electrode morphology (increase in grain size and roughness), in the surface composition and microscopic aspect, with a partial passivation effect on the film electrochemical behaviour. The formation of surface deposits with a characteristic, elongated shape has been revealed to occur after 500 Li charge–discharge cycles. Submicron chemical analysis of such deposits onto aged oxide electrodes has been performed by SPEM, which enabled the location and assignment of the surface composition.