Silvia Bruni

First dairying in green Saharan Africa in the fifth millennium bc

In the prehistoric green Sahara of Holocene North Africa—in contrast to the Neolithic of Europe and Eurasia—a reliance on cattle, sheep and goats emerged as a stable and widespread way of life, long before the first evidence for domesticated plants or settled village farming communities. The remarkable rock art found widely across the region depicts cattle herding among early Saharan pastoral groups, and includes rare scenes of milking; however, these images can rarely be reliably dated. Although the faunal evidence provides further confirmation of the importance of cattle and other domesticates, the scarcity of cattle bones makes it impossible to ascertain herd structures via kill-off patterns, thereby precluding interpretations of whether dairying was practiced. Because pottery production begins early in northern Africa the potential exists to investigate diet and subsistence practices using molecular and isotopic analyses of absorbed food residues. This approach has been successful in determining the chronology of dairying beginning in the ‘Fertile Crescent’ of the Near East and its spread across Europe. Here we report the first unequivocal chemical evidence, based on the δ13C and Δ13C values of the major alkanoic acids of milk fat, for the adoption of dairying practices by prehistoric Saharan African people in the fifth millennium bc. Interpretations are supported by a new database of modern ruminant animal fats collected from Africa. These findings confirm the importance of ‘lifetime products’, such as milk, in early Saharan pastoralism, and provide an evolutionary context for the emergence of lactase persistence in Africa.

Spectrochemical characterization by micro-FTIR spectroscopy of blue pigments in different polychrome works of art

Abstract Analytical examination of blue paint samples, taken from different artworks dating from the second century AD until 1960, was carried out using FTIR microspectroscopy (both in reflection and transmission mode, the latter with the aid of a diamond cell) supported by micro-Raman spectroscopy and SEM observations as well as EDX spectrometry. Pigments examined included azurite, Egyptian blue and ultramarine blue, either natural or artificial. Characteristic spectra for each pigment are presented and an account for the principal differences observed is given. In particular, the FTIRs capability of probing single pigment grains on the surface of paint cross-sections, when integrated with a microscope, brought to light frequency differences and orientation behaviour of the bands of the various minerals used as painting materials. Indeed, a striking effect of shifting and variation of intensity of some of the bands of azurite and Egyptian blue was noted and related to polarization phenomena occurring when the incident light stroke differently oriented faces of the single pigment crystals. The effects of different mineralogical composition of the semi-precious stone lapis-lazuli (from which ultramarine blue is derived) on the appearance of the spectrum of the pigment are also discussed. Finally, a means of distinguishing the natural from the artificial ultramarine blue pigment, on the basis of their FTIR spectra, is proposed.

Sample treatment considerations in the analysis of organic colorants by surface-enhanced Raman scattering.

The introduction of surface-enhanced Raman spectroscopy (SERS) in the field of cultural heritage has significantly improved the analysis of the organic dyes and their complexes that have been used as textile dyes and pigments in paintings and other polychrome works of art since antiquity. Over the last five years, a number of different procedures have been developed by various research groups. In this Article, we evaluate the effect of pretreating samples by exposing them to hydrofluoric acid (HF) vapor prior to SERS analysis, a step designed to hydrolyze the dye-metal complexes and increase analyte adsorption on the nanosized metallic support, thus enhancing the SERS signal. Materials studied include pure colorants, commercial lake pigments, and fibers from dyed textiles, as well as actual aged samples, such as microscopic fragments of lakes on paper and ancient pigments and glazes from several works of art, covering a wide range of time, from the second century B.C. to the early 20th century. In each case, SERS spectra obtained with or without HF hydrolysis were critically evaluated. The pretreatment with HF vapor resulted in faster analysis and increased sensitivity in most cases, with the exception of dyed silk fibers, where silk protein hydrolyzates were found to interfere with SERS analysis. As a final point, a two-step procedure including SERS on untreated and treated samples is proposed as a standard approach: by analyzing a sample first without hydrolysis, and then, following removal of the colloid, upon HF treatment, the best and most reliable results for a great number of dyes and substrates are assured.

Determination of the quadratic hyperpolarizability of trans-4-[4-(dimethylamino)styryl]pyridine and 5-dimethylamino-1,10-phenanthroline from solvatochromism of absorption and fluorescence spectra: a comparison with the electric-field-induced second-harmonic generation technique

For fluorescent compounds, the combined use of absorption and emission solvatochromic data allows to estimate indirectly the cavity radius of the molecule in solution, a very critical parameter in the application of the solvatochromic method for the determination of the quadratic hyperpolarizability beta of dipolar molecules. For two test compounds, trans-4-[4-(dimethylamino)styryl]pyridine (DASP) and 5-dimethylamino-1,10-phenanthroline (DAPHEN), the beta values so obtained are compared with those obtained by the EFISH (Electric Field Induced Second-Harmonic generation) technique. For DAPHEN, the versatility of the method described in this work in the presence of more than one electronic transition contributing to the non-linear optical response is demonstrated.

Characterization of ancient magnesian mortars coming from northern Italy

Abstract Different ancient mortar samples were analyzed to characterize their binder fraction. Thermal analyses (TG, DSC) proved to be very useful in the identification of three different species of lime composed of: (a) only calcite; (b) calcite and magnesite; (c) calcite, hydromagnesite and magnesite. The hydromagnesite is well identified in the DSC curve showing the peaks corresponding to the three-step thermal decomposition. Also the same mineral was detected by FTIR and/or micro-FTIR analyses, depending on its amount in the binder fraction of the mortar. Actually, the two absorption peaks characteristic of the hydromagnesite were often hidden by the wider peaks due to the asymmetric stretching of the carbonate ion, observed for the calcite and magnesite.

Identification of pigments on a XV century illuminated parchment by Raman and FTIR microspectroscopies

Abstract The pigments used to illuminate a precious, richly decorated XV century document on parchment, the property of the State Archives of Milan, have been thoroughly investigated by the complementary use of Raman and reflectance Fourier transform infra red (FTIR) microspectroscopies, both performed non-destructively and in situ. The palette has been determined and the pigments used unambiguously characterised. These were all natural mineral pigments: azurite, ultramarine blue, malachite, vermilion and minium. The advantages and disadvantages of each technique, with respect to the identification of single pigments, are discussed, especially in the cases of malachite and ultramarine blue.

Field and Laboratory Spectroscopic Methods for the Identification of Pigments in a Northern Italian Eleventh Century Fresco Cycle

The pigments of an XI-century fresco cycle in a small pre-alpine church of northern Italy were characterized by means of field techniques, in particular imaging spectroscopy, and laboratory spectroscopic techniques, namely total reflection X-ray fluorescence, micro-Raman, micro-Fourier transform-Raman, and micro-Fourier transform infrared spectroscopies, thus achieving a complete identification of the ancient painters palette. Advantages and limitations of each technique in its application to the study of fresco pigments are discussed. The artistic value of the fresco cycle and the religious role in the year 1000 of the church where it is located (S. Michele Arcangelo in Gornate Superiore, Varese, Italy) were demonstrated by the precious and elaborate materials used by the painter. Different pigments were used for different hues of the same color, e.g., azurite, carbon, and the most precious lapis-lazuli for blue, while mixtures of pigments were recognized in details having a particular tint, e.g., lapis-lazuli and minium for violet.

POlymeric Complexes of 3-Hydroxy-4-Methoxy- And 3-Methoxy-4-Hydroxybenzoic Acids. Crystal Structure of the Linear-Chain Complex of COII With 3-Hydroxy-4-Methoxybenzoic Acid

Abstract Reaction of CuII, CoII, and NiII with 3-hydroxy-4-methoxy- and 3-methoxy-4-hydroxybenzoic acids (hmba and mhba, respectively) yields hydrated complexes exhibiting stoicheiometries with 1:2 and 1:1 metal to ligand mol ratios. The 1:2 complexes, formed by CoII with hmba and CuII with mhba, involve carboxylate groups and water molecules as donors. The structure of [Co(hmba)2(H2O)3] was determined by single-crystal X-ray analysis. It crystallizes in the monoclinic space group 12/a with a = 8.164(2), b = 11.171(3), c = 20.980(5) A, β = 91.42(3)°, and Z = 4. The complex is a one-dimensional polymer with bridging water molecules (Co-H2O-Co = 128.04° and Co … Co = 4.082 A). The hexacoordination at each cobalt is completed by oxygens from two monodentate carboxylates and two water molecules. Stacking interactions between the parallel aromatic rings (3.5 A) hold neighbouring chains together. Complexes with a 1:1 metal to ligand ratio (M = CuII, CoII and NiII, L = hmba; M = CoII and NiII, L = mhba) also cle...

Micro-Raman identification of the palette of a precious XVI century illuminated Persian codex

Abstract A remarkable, richly decorated Persian manuscript dating from 1537 was investigated by Raman microscopy in order to assess the nature of the pigments used. Although the decorated area measures just a few tens of cm 2 and doesn’t include any anthropomorphic motif, but consists in a very geometric, lacework-like decoration, it contains very elaborate and precious details. A very rich palette was revealed, showing extensive use of the extremely valuable and costly pigment lapis-lazuli, gold and orpiment, besides malachite, vermilion and red lead. With the exception of the choice for an expensive pigment such as lapis-lazuli even for the background, the experimental data confirm that the art of miniature making, as well as the painting materials used in the Middle East, didn’t actually differ much from what is considered to be the acknowledged practice for western art in the same period.

ORGANIC/INORGANIC COMPOSITE MATERIALS : SYNTHESIS AND PROPERTIES OF ONE-DIMENSIONAL POLYMERIC HALOPLUMBATE(II) SYSTEMS

Abstract In this paper we report the synthesis and the thermal, spectroscopic and electrical characterization of 1-D polymeric haloplumbates(II) of formula (A) [PbX3] (A = piperidinium] (pdH), morpholinium (mpH) cation; X = Br, I for pdH and Cl, Br for mpH). For the morpholinium compounds we report also the structural analysis. The (mpH) [PbX3] (X = Cl, Br) complexes are isomorphous and crystallized space group P212121. The unit cell dimensions are a = 15.249(3), b = 8.001(2), c = 7.625(2) A , V = 930.3(4) A 3 , Z = 4 for (mpH) [PbCl3] and a = 15.760(3), b = 8.254(2), c = 7.866(6) A , V = 1023.2(4) A 3 , Z = 4 for (mpH) [PbBr3]. The final R value is 0.0428 (Rw = 0.0442) for (mpH) [PbCl3] and 0.0434 (Rw = 0.0453) for (mpH) [PbBr3]. The structure consists of morpholinium cations and infinite polymeric anions [PbX3−]n; each lead atoms is surrounded by six halogen atoms forming a strongly distorted octahedronl adjacent octahedra share faces to form 1-D endless chains in which two consecutive lead atoms are bridged by three halogen atoms. The distortion in the (PbX6) octahedra of (mpH) [PbX3] enables the metal ion to be involved in a semicoordinative bond with the oxygen atom of the morpholinium cation, which makes the lead(II) coordination 6 + 1. All the structures are tridimensionally built up by a network of intermolecular NH⋯X bonds.