Analytical characterization of paintings on pre-Roman pottery by means of spectroscopic techniques. Part II: Red, brown and black colored shards

As a part of a systematic study aimed at assessing the chemical composition of ancient pigments as well as at collecting information useful for the understanding of the technical aspects related to pottery preservation and decoration, the results of analysis performed on red, brown and black pigments decorating pre-Roman pottery excavated in thirteen different tombs unearthed in the archaeological zone of Canosa (Puglia, Italy) are presented. Both surface (XPS) and bulk (FT-IR) spectroscopies were used which gave complementary information and XRD was used in some cases to further support the spectral assignments. Results suggested that the shards characterized by “nominally” the same color could be differentiated by the chemical composition of the pigmented layers; in particular, the shards exhibiting the red pigment could be divided into three groups containing, respectively, either hematite or ochre plus other substances not related to the color but of great concern for the understanding of ancient techniques used for color preparation. Manganese oxides were found to be the basis of the brown pigments, which could be divided into three groups on the basis of Mn and Fe contents. Either magnetite or carbon of vegetable origin was found in the black-pigmented layers. Furthermore, an attempt was made to find a possible correlation between this classification and the results of a provenance study carried out on the same pool of shards analyzed in the present investigation. Received: 28 May 1999 / Revised: 6 August 1999 / Accepted: 21 August 1999     

Effects of Lactobacillus rhamnosus on zebrafish oocyte maturation: an FTIR imaging and biochemical analysis

The aim of this study was to verify the effects of probiotic Lactobacillus rhamnosus on zebrafish oocyte maturation using FPA (focal plane array) FTIR imaging together with specific biochemical assays (SDS-PAGE, real-time PCR and enzymatic assay). Oocyte growth is prevalently due to a vitellogenic process which consists of the hepatic synthesis of vitellogenin and its selective uptake during maturation. The administration of L. rhamnosus IMC 501 for 10 days induced chemical changes to oocyte composition, promoting the maturation process. Some interesting biochemical features, linked to protein secondary structure (amide I band) and to phospholipidic and glucidic patterns, were detailed by vibrational analysis. The spectroscopic results were supported by the early increase of the lysosomal enzyme involved in the final oocyte maturation, the cathepsin L. This enzyme increases during follicle maturation, with the highest levels in class IV oocytes. In treated females, class III oocytes showed higher cathepsin L gene expression and enzymatic activity, with levels comparable to class IV oocytes isolated from controls; this can be related to the proteolytic cleavage of the higher molecular mass yolk protein components, as evidenced by SDS-PAGE.     

FTIR microspectroscopy of melanocytic skin lesions: a preliminary study

Fourier transform infrared (FTIR) microspectroscopy has been employed to investigate benign (ordinary dermal and Reed nevi), dysplastic and malignant (invasive melanoma) skin lesions through the analysis of spectral changes of melanocytes as well as in the evaluation of the presence of melanin. Hierarchical cluster analysis and principal component analysis led to a satisfactory separation of malignant from dysplastic and normal melanocytes. Also, on enlarging the clustering with spectra from Reed and dermal nevi, the multivariate analysis segregated well the spectral data into discrete clusters, allowing the obtaining of reliable average spectra for analysis at the molecular level of the main groups or components responsible for the biological and biochemical changes. The most significant spectral characteristics appear to be related to differences in secondary protein structures, in nucleic acid conformation, in intra- and intermolecular bonding. In all cases, supervised and unsupervised spectral analyses resulted in satisfactory agreement with histopathological findings.     

Analytical investigations of poly(acrylic acid) coatings electrodeposited on titanium-based implants: a versatile approach to biocompatibility enhancement

A polyacrylic acid film was synthesized on titanium substrates from aqueous solutions via an electroreductive process for the first time. This work was done in order to develop a versatile coating for titanium-based orthopaedic implants that acts as both an effective bioactive surface and an effective anti-corrosion barrier. The chemical structure of the PAA coating was investigated by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) was employed to evaluate the effect of annealing treatment on the morphology of the coatings in terms of their uniformity and porosity. Inductively coupled plasma mass spectrometry was used to measure ion concentrations in ion release tests performed on Ti-6Al-4V sheets modified with PAA coatings (annealed and unannealed). Results indicate that the annealing process produces coatings that possess considerable anti-corrosion performance. Moreover, the availability and the reactivity of the surface carboxylic groups were exploited in order to graft biological molecules onto the PAA-modified titanium implants. The feasibility of the grafting reaction was tested using a single aminoacid residue. A fluorinated aminoacid was selected, and the grafting reaction was monitored both by XPS, using fluorine as a marker element, and via quartz crystal microbalance (QCM) measurements. The success of the grafting reaction opens the door to the synthesis of a wide variety of PAA-based coatings that are functionalized with selected bioactive molecules and promote positive reactions with the biological system interfacing the implant while considerably reducing ion release into surrounding tissues. Figure Vanadium release from bare Ti-6Al-4V sheets compared with the release from sheets coated with annealed and unannealed electrosynthesised PAA Dedicated to Professor P.G. Zambonin on the occasion of his 72nd birthday.     

Analytical characterization of bioactive fluoropolymer ultra-thin coatings modified by copper nanoparticles

Copper–fluoropolymer (Cu-CFx) nano-composite films are deposited by dual ion-beam sputtering. The extensive analytical characterization of these layers reveals that inorganic nanoparticles composed of Cu(II) species are evenly dispersed in a branched fluoropolymer matrix. In particular, X-ray photoelectron spectroscopy has been employed to study the surface chemical composition of the material and to assess how it changes on increasing the copper loading in the composite. Transmission electron microscopy reveals that the copper nanoclusters have a mean diameter of 2–3 nm and are homogeneously in-plane distributed in the composite films. Electrothermal atomic absorption spectroscopy has been used to study the kinetics of copper release in the solutions employed for the biological tests. The Cu-CFx layers are employed as bioactive coatings capable of inhibiting the growth of target microorganisms such as Saccharomyces cerevisiae, Escherichia coli, Staphylococcus aureus, and Lysteria. The results of the analytical characterization enable a strict correlation to be established among the chemical composition of the material surface, the concentration of copper dissolved in the microorganisms broths, and the bioactivity of the nano-structured layer.     

Absorption and emission properties of a europium(II) cryptate in aqueous solution

The absorption spectrum of the complex between Eu²⁺ and the [2.2.2] cryptand shows narrow, weak transitions within 4f⁷ superimposed on broad, strong transitions from 4f⁷ to 4f⁶ 5d. Emission from 4f⁶5d to 4f⁷ can be observed at 77 K λ_max = 420 nm, τ = 0.55 μs) and at 293 K (λ_max = 460 nm, τ = 3 ns) in aqueous solution.