Analysis of ancient mycolic acids by using MALDI TOF MS: response to “Essentials in the use of mycolic acid biomarkers for tuberculosis detection” by Minnikin et al., 2010

The mycobacterial cell wall is consists of several long chain lipid and glycolipid components. Mycolic acids are major and unique fraction of the cell envelope of mycobacteria that include the ancient causative agents of tuberculosis and leprosy. The analytical investigation of these lipid biomarker residues is one of the most promising perspectives in the field of molecular paleopathology. Recently published in this journal, Minnikin et al. present a systematic critique of the MALDI TOF MS analysis for determination of ancient mycolic acids, focusing on our previous paper. In this study, our mass spectrometric investigations by commonly used 2,5 DHB matrix were presented with our comments to the critique authors. On the base of our previous and recent mass spectrometric results we have to realize that the clinical protocols and standards cannot directly be used for the biomolecular paleopathological investigations. The applicability of the recent mycobacterial and clinical results is very limited in the biomolecular archaeology, thus the recent scientific results and protocols should be adapted carefully to bioarchaeological sciences.     

NO STONE UNBURNED: A COMPOSITIONAL ANALYSIS OF OBSIDIAN MICRODEBITAGE BY LASER ABLATION TOF–ICP–MS

Obsidian is an effective material for the study of prehistoric raw material use and exchange, due to the high degree of homogeneity and redundancy of obsidian materials and manufactured objects in the archaeological record. The destructive nature of many analytical techniques often impedes compositional research because of the damage that may occur to priceless archaeological artefacts. The combination of time‐of‐flight (TOF) ICP–MS with a laser ablation sample introduction system provides a highly efficient means of chemically characterizing obsidian. This study shows that sample size limit capabilities of TOF–ICP–MS analysis of obsidian can reach less than 100 μm. Sampling and analysis of microartefacts enables researchers to overcome problems of sampling bias with very little damage to the valuable existing materials within the archaeological record and expands the potential for chemical compositional analyses in archaeology.     

From Byzantine to post-Byzantine art: the painting technique of St Stephen's wall paintings at Meteora,Greece

The old katholikon of St Stephen's monastery at the Meteora (site of the most important complex of monasteries in Greece after Mount Athos) is decorated with wall paintings that date from the beginning of 17th century. In terms of style, the artistic ensemble is altogether characteristic of the period. The painting technique has been examined by means of μRaman and μFTIR spectroscopies, gas chromatography–mass spectroscopy (GC/MS), optical microscopy (OM) and scanning electron microscopy (SEM).     

Identification of the Residue in the Bolgar Medieval Sphero‐Conical Vessel by Gas Chromatography – Mass Spectrometry

The Golden Horde sphero‐conical vessel retrieved from the ruins of the medieval city of Bolgar (Russia, Republic of Tatarstan) during archaeological excavations, which contained residue in the form of encrustation on the bottom and the wall, was analysed in the NRC ‘Kurchatov Institute’ by X‐ray phase analysis and high‐performance liquid and gas chromatography with MS detectors (HPLC–MS, GC–MS). The GC–MS method established that the residue from the sphero‐conical vessel was comprised primarily of abietic acid derivatives (around 46%) and retene, which is polycyclic aromatic hydrocarbon (around 27%); this means that turpentine exuded from the stems of certain species of coniferous trees, called resin and subsequently heat‐treated, was poured into the vessel. Researchers have been trying to decipher the function of these mysterious vessels for 200 years, and this is the first time that resin stored in a sphero‐conical vessel has been documented. Potentially, this vessel was probably used as a personal ‘medical kit’.     

The Temple of Venus (Pompeii): a study of the pigments and painting techniques

We report here on a study of 57 fragments of wall painting excavated from the Temple of Venus (Pompeii). These samples were characterised by a wide range of analytical methods. Data showed that the palette is varied, although not so broad as that found in other buildings in Pompeii, and is consistent with pigments used elsewhere in Pompeii and in the Roman Empire. It is composed of: natural earths, minerals and rare artificial pigments. Paintings are made up of thin paint layers (0.01–0.10 mm thick) strongly adhering to the underlying preparation layer. Nonetheless, in some cases thicker layers (up to 0.40 mm) were recognised, often spread on other previous painting layers. Samples were also compared with the microstratigraphic criteria developed in Piovesan (2009) to distinguish wall painting techniques. This comparison demonstrated that both fresco and lime painting techniques were adopted.     

云南剑川海门口遗址饱水古木降解的微观构造分析

文中采用扫描电镜(SEM)和透射电镜(TEM)对海门口遗址饱水古木进行降解机理分析。结果表明:古木细胞次生壁收缩严重并与胞间层分离;胞间层保存较完好,呈连续网状。说明古木纤维素和半纤维素降解相对严重,木质素降解相对较轻。古木主要是受细菌降解,通过SEM和TEM均可见明显的细菌腐朽特征。细菌首先侵入细胞腔,再通过S3层侵入细胞壁内部。细胞壁内由于降解而产生的空隙在几十到几百纳米之间。饱水古木也受到了一定程度的真菌降解,但这类真菌主要降解古木内淀粉等物质,对细胞壁物质降解能力差,主要是使古木变色。     

DETERMINATION OF PIGMENTS AND BINDERS IN POMPEIAN WALL PAINTINGS USING SYNCHROTRON RADIATION – HIGH‐RESOLUTION X‐RAY POWDER DIFFRACTION AND CONVENTIONAL SPECTROSCOPY – CHROMATOGRAPHY

The employment of synchrotron techniques complemented by conventional laboratory systems has allowed us to deepen and improve our knowledge of Roman wall painting procedures. The palette identified in wall paintings from Pompeii and Herculaneum from the second century bc includes goethite, hematite, cinnabar, glauconite, Egyptian blue, and other components such as calcite and aragonite. Proof of the use of organic binders is provided by FTIR and PY–GC/MS. Therefore, the possibility of the use of ‘a secco’ techniques cannot be ruled out. Pigments in wall paintings are usually found in small percentages and conventional X‐ray diffractometers do not detect them. Synchrotron radiation – high‐resolution X‐ray powder diffraction has allowed identification with only a few micrograms of sample.     

Identification of Green Pigment Used in Persian Wall Paintings (ad 1501–1736) Using PLM,FT–IR,SEM/EDX and GC–MS Techniques

The technique of oil painting was introduced to Iran via a cultural exchange with Europe in the Safavid period (ad 1501–1736). Since the first attempt at scientific conservation of wall paintings in Iran in the 1960s, the nature of green pigment used in Persian wall paintings has not been clear, although work on contemporary miniature paintings has identified malachite and verdigris. PLM, FT–IR, SEM/EDX, GC–MS and the study of contemporary historical treatises of the Safavid period were the main tools used in the present study to identify the green pigments in Persian (oil‐based) wall paintings. Eight samples taken from the two famous Safavid buildings, Chehel Sotoon Palace and the Sukias House in Isfahan, were analysed. Here, the identification of copper‐based pigment and of verdigris in oil as oleate amends the existing knowledge of the green pigment used in these paintings. It also suggests that oleate was introduced to Persian artists via the European influence on Persian painting as a result of cultural exchange in the Safavid period, when the technique of Persian painting changed from tempera to oil painting. However, as verdigris in oil and resin can appear as oleate over time, it is unknown whether the Persian artists did this deliberately or accidentally.     

The Byzantine wall paintings from the Protaton Church on Mount Athos,Greece: tradition and science

The present work is a study of the wall painting complex in the Protaton Church (1295) on Mount Athos, Greece. These paintings, high in artistic value, are themselves a monument—representative of the Macedonian iconographic style. What follows is historic data set against the results of analytical investigations: the fruit of extensive research aimed at determining precise details about the applied painting techniques for the wall paintings. Hitherto it has been held that what was traditionally defined as “Byzantine fresco” was executed only on wet plaster with limewater as the sole binding medium. Now, however, through the application of instrumental analytical investigations, it is possible to demonstrate that a mixed technique involving both al fresco and al secco was employed. Furthermore, it was determined, on the basis of results from gas chromatography–mass spectrometry (GC/MS), that egg together with a modest amount of animal glue were the organic binding media used for the Protaton art work. It is certain that the scenes were initially begun on wet plaster. During or even after drying the painting was completed using the aforementioned protein binding media, thanks to which a more resistant cohesion to the painted layers was secured.     

Characterization of organic media in the wall-paintings of the “Palace of Nestor” at Pylos,Greece: evidence for a secco painting techniques in the Bronze Age

This paper presents the results of an investigation of organic binding media detected in samples from the Mycenaean wall-paintings at the “Palace of Nestor” in Pylos (Western Messenia, Greece): samples dated from the Late Bronze Age (ca. 1200 BC). This is the first scientific study to be conducted on organic binding media in Mycenanean painting, and it is a study that aims to contribute significantly towards our understanding of the original painting techniques used during the Bronze Age. The analytical procedures employed for the detection and characterization of the organic substances preserved within the paint layers (proteinaceous materials, lipids and plant gums), were based on chromatography/mass spectrometry techniques (PY–GC/MS, GC/MS). The most significant results, highlighting an a secco painting technique, are herein reported and discussed.     

The painting of the Etruscan “Tomba della Quadriga Infernale” (4th century BC), in Sarteano (Siena, Italy): technical features

This work presents the results of an investigation of the painting technique used in the Etruscan tomb “Tomba della Quadriga Infernale”. This tomb was discovered in Sarteano (Siena, Italy) in October 2003 and dated back to the second half of the 4th century BC. Red, dark red, pink, yellow, white, black, and grey colours were used in the tomb in order to create paintings, which now represent a very precious record of the Etruscan art of wall painting in a hypogeal environment. The technical features of the painting were revealed by stratigraphy using optical and electronic microscopy. The components and preparatory layers of the painted areas were characterized using Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray microanalysis (SEM-EDS), X-ray diffraction (XRD), and gas chromatography/mass spectrometry (GC/MS). XRD, SEM-EDS, and optical microscopic techniques were also used for mineralogical analysis of the rock substrate. The SEM-EDS and FTIR analyses showed that red and yellow ochre, calcite, and vegetable charcoal were used to paint the walls of the tomb: the pigments, either alone or mixed together, were utilized to produce pure colours (red, yellow, white, and black) and intermediate tonalities (pink, dark red, and grey). SEM-EDS, FTIR, and XRD highlighted that the painting was made on a preparatory layer of calcite, applied onto a levelling material made up of calcite, clay minerals, quartz, and iron oxides. GC/MS analyses revealed that egg was used as an organic binder to disperse the pigments.     

Identification of psychoactive alkaloids in ancient Andean human hair by gas chromatography/mass spectrometry

Various ethnographic sources have demonstrated the symbolic and ritualistic importance of psychoactive plants in Native American societies. The social milieu of these mind- altering plants appears to be ancient. Archaeological evidence during the Tiwanaku empire expansion along the Atacama Desert of Chile, circa 500–1000 A.D., shows the presence of highly decorated snuffing tablets and tubes as grave goods. The preservation of mummified human bodies in the Azapa Valley, northern Chile, provided an opportunity to test the exact nature of the psychoactive plants used in this region. Using gas chromatography/mass spectrometry (GC–MS), here we show that ancient Andean populations from northern Chile consumed Banisteriopsis, a vine that contains harmine. This is the first direct archaeological evidence of hallucinogenic and medicinal ethnographic practices. Interestingly enough, this rainforest plant does not grow along the Atacama coast, thus our findings suggest extensive plant trade networks in antiquity as far as the Amazon.     

PREHISTORIC WALL PAINTINGS: THE CASE OF THE DOMUS DE JANAS NECROPOLIS (SARDINIA,ITALY)*

The Domus de Janas (Home of the Fairies, or Home of the Witches) are Neolithic hypogea located throughout Sardinia (Italy) and decorated with red and black wall paintings. The objective of this study was to define the painting technique through the analytical characterization of the pigments and binding media. Samples of painting film from different graves have been examined by means of various analytical techniques. XRD, Raman and SEM–EDX analyses identified the red and black pigments respectively as red ochre rich in hematite and carbon black, while GC–MS analyses characterized the organic binder as egg.     

Characterization and origin of black and red Magdalenian pigments from Grottes de la Garenne (Vallée moyenne de la Creuse-France): a mineralogical and geochemical approach of the study of prehistorical paintings

Pigments sampled from wall paintings and from crayons taken on the floor, at the Grottes de la Garenne (Saint-Marcel – Indre, France) have been analyzed and characterized by infrared spectroscopy, Raman micro-spectroscopy, X-ray diffraction, ICP/MS and analytical TEM. The red pigment used for the wall paintings is mainly composed by hematite, clays, carbon matter and carbonates. Results on the red pigments show that the compositions of the paintings are similar to that of some crayons. Regarding these analyses, their origin is compatible with local siderolithic facieses. Analysis of black pigments shows that they are made of cryptomelane, pyrolusite, clays, carbonates and carbon matter. It shows also that paintings and some crayons compositions are compatible. On the contrary of red pigments, the origin of black pigments is probably allochtonous. Indeed, the traces of thallium detected in cryptomelane, the cerium anomaly and the absence of iron are not compatible with local facieses or other sites from the French Massif Central.     

Detecting and mapping buried buildings with Ground-Penetrating Radar at an ancient village in northwestern Argentina

We describe an archaeo-geophysical investigation performed near the Palo Blanco archaeological site, Catamarca, Argentina. A large area beyond the northern limit of the site was explored with the Ground-Penetrating Radar (GPR) method in order to detect new buildings. The exploration showed signals of mud-walls in a sector that was located relatively far from the previously known buildings. A detailed survey was performed in this sector, and the results showed that the walls belonged to a large dwelling with several rooms. The discovery of this dwelling has considerably extended the size of the site, showing that the dwellings occupied at least twice the originally assumed area. High-density GPR surveys were acquired at different parts of the discovered building in order to resolve complex structures. Interpreted maps of the building were obtained. Different characteristics of the walls were satisfactory determined, in spite of the low contrast of the dielectric constant at their interfaces and the noticeable spatial fluctuations of the signals due to wall collapses.     

Non-destructive Phase Analysis of Archaeological Ceramics using TOF Neutron Diffraction

Mineral phase analysis of ancient ceramics carried out by neutron diffraction yields complementary information to X-ray diffraction analysis. Since neutrons are highly penetrating, neutron diffraction in general allows non-destructive investigations of bulk samples rather than of surface layers or powdered material. This means complete, intact specimens can be studied. A time-of-flight (TOF) neutron diffractometer offers additional advantages considering experimental set-up, accommodation of large objects and data collection times. First test measurements with respect to archaeometric applications have been performed on different fragments of medieval Rhenish pottery using the TOF neutron diffractometer ROTAX at the spallation source ISIS, U.K. Phase fractions obtained from a Rhenish stoneware jar fragment compare well with those from a powder sample prepared from the same fragment. This finding indicates that reliable results can be obtained by illuminating a large piece or even a complete ceramic object without causing damage.     

POROSITY DETERMINATION WITH HELIUM PYCNOMETRY AS A METHOD TO CHARACTERIZE WATERLOGGED WOODS AND THE EFFICACY OF THE CONSERVATION TREATMENTS

The helium pycnometer allows us to measure the cell‐wall density of dry woods and the basic density of wood samples soaked with water and/or a consolidant solution if a non‐volatile solvent is used. These parameters were correlated to the porosity, which for degraded waterlogged wood is related to the maximum water content. Moreover, this has revealed the possibility of investigating, by means of accurate cell‐wall density determination, the efficacy of several consolidants in the treatment of waterlogged woods.     

A short note on starch and xylem of Ipomoea batatas (sweet potato) in archaeological deposits from northern New Zealand

This study examines preservation of microfossils identified as introduced Ipomoea batatas in soils from northern New Zealand. Starch grains and xylem cells showed highly variable preservation, from good to extremely poor. For starch grains, the latter included brown-staining, expansion and distortion of the grain and vacuole, loss of the Maltese cross, pitting, cracking, fragmentation and disintegration. Degraded xylem showed similar brown-staining, occasional cracking, cross-wise fragmentation, with wall pits becoming progressively less visible or showing distortion, expansion and coalescence.