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Bronzes are largely used in various domains such as battery connectors, archaeological artefacts and urban statues, suffering from corrosion process leading to the formation of corrosion products. A protection treatment could be used to insulate them from this environment. In this way we contribute to the protection of bronze in the environment by use of organic corrosion inhibitors. In this work a novel organic compound (3-phenyl-1·2·4-triazole-5-thione) was tested as a corrosion inhibitor on a pure reference bronze alloy (CNR alloy). The electrochemical behaviour was investigated in 3%NaCl solution, in the presence and absence of the inhibitor formulation using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS). The obtained results confirm that the compound is a good corrosion inhibitor which acts reduce both cathodic and anodic reactions rates. The inhibiting efficiency was found to be about 97% at 2·5 mM of inhibitor concentration. SEM coupled with EDX and XPS analysis confirms the good protective effect due to the establishment of an inhibitor film on the bronze sample. [ABSTRACT FROM AUTHOR]

A large number of pyrometallurgical materials such as tuyeres, slags and refractory tools likely associated with metal extraction processes have been found at Tharros (north-western Sardinia, Italy) during archaeological excavations stratigraphically related to the Phoenician–Punic period (VI–III centuries BC). Micro-chemical, micro-structural and mineralogical studies have been carried out by means of the combined use of X-ray diffraction (XRD), selected-area X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) in order to identify pyrometallurgical processes and main relevant technological parameters. The results reveal that tuyeres, slags and refractory tools can be associated with an iron ore smelting process to extract the metal by slagging the unwanted by-products. Moreover, temperature and duration of the smelting process have been estimated through mineralogical studies and by a comparative analysis between the micro-chemical and structural features of thermally treated refractory materials and tuyeres. The results disclose the high level of technological competence of the ancient metallurgists able to carry out complex high-temperature processes to extract iron from ores by separating the metal from unwanted siliceous species. [ABSTRACT FROM AUTHOR]

While protected areas are a centrepiece of conservation, populations of animals in protected areas can still be subject to considerable human influence. Conservation theory suggests that many species should live at lower densities at the periphery of protected areas compared with the core area. Similarly, but more specifically, species subject to exploitation are expected to have lower densities in areas close to human settlements compared with more remote areas. Drawing upon distributional data of eight large African herbivore species (buffalo Syncerus caffer, elephant Loxodonta africana, giraffe Giraffa camelopardalis, impala Aepyceros melampus, topi Damaliscus lunatus, warthog Phacochoerus africanus, waterbuck Kobus ellipsiprymnus and zebra Equus quagga) sampled using ground surveys in 1995 and 1996, and seven large herbivore species (the same species without impala) sampled using aerial surveys from 1987 to 2009, we fitted logistic regression models and used an information theoretic model selection approach to test these two hypotheses in an East African savannah national park subject to illegal hunting from outside. In the vast majority of herbivore species, occupancy was not substantially affected by being close to the edge of the park or in close proximity to human villages. Furthermore, population declines witnessed in this protected area were not reflected in reduced occupancy near park boundaries. We conclude that assumed distributional differences between peripheral and core parts of reserves are not necessarily supported by empirical evidence, and that population declines within reserves do not inevitably proceed from boundaries inwards. [ABSTRACT FROM AUTHOR]

Since ancient times, precious metallic artefacts have gained a remarkable interest from a historical, artistic and economical point of view. They were used as jewels or artistic items but also for currency, medium of exchange and form of saving, and in many cases were manufactured with a high level of technological competence. Several Roman and Phoenician-Punic gold, silver and copper-based, gold and silver-plated artefacts characterised by a wide compositional range and different metallurgical nature have been studied to identify the microchemical surface structure and the metallurgical features. Four case studies are reported. The investigation was carried out by means of the combined use of surface and microanalytical techniques, such as XPS, X-ray diffraction and SEM equipped with an energy dispersive X-ray spectrometer. The results revealed that the artefacts surface is characterised by a thin layer of insoluble corrosion products like AgCl, Ag2S or AgCuS, CuS, Cu2O, Pb or Cu-carbonates mixed to form a complex composite structure. The presence and the concentrations of these corrosion compounds is strongly related to the archaeological context. The overall experimental findings confirm that the nearly pure gold artefacts and the gold-based artefacts are more stable with respect to the silver ones where the ubiquitous presence of chlorides is often found. The microchemical and micromorphological characterization allows to identify the plating and manufacturing techniques. Several methods were used by the craftsmen, including fire gilding, a highly complex and sophisticated method based on the use of mercury. Finally, the proposed approach may help, when feasible, to preserve, restore and protect the artefacts without causing further damaged. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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The micro-chemical and micro-structural nature of inorganic thick encrustations, deposited during long-term archaeological burial on Roman, Greek and medieval ceramic artefacts and obscuring significant decoration details, were investigated by means of scanning electron microscopy combined with energy-dispersive spectrometry, optical microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and differential thermal analysis and thermogravimetry. Analytical results showed the presence of carbonates mixed with low amounts of silicate, chlorides, sulphates and phosphates containing Ca, Fe, Na, K, Al and Ti. Extensive preliminary comparative trials and different chemical cleaning methods and materials were used to remove the thick carbonatic encrustations without altering the underlying coloured decoration layers. The micro-chemical and micro-morphological characterisation of the cleaned ceramic surfaces showed that a styrene-divinylbenzene copolymer cationic resin with fine particle size represents a reliable and effective cleaning material when applied under controlled conditions (temperature = 30 °C, relative humidity = 100%, application time = 24 h) by using a simple, low-cost and safe procedure. [ABSTRACT FROM AUTHOR]

Mammalian carnivores are unusual because their primary competitors for food are often their primary predators. This relationship is most evident at persistent kills where dominant competitors are attracted to both the carcass (as a free meal) and to the killers (as potential prey). Cheetahs ( Acinonyx jubatus) are frequent victims of kleptoparasitism, and cubs, and sometimes adults, are killed by lions ( Panthera leo) or spotted hyenas ( Crocuta crocuta). Between 1980 and 2002, we observed 639 kills made by cheetahs in Serengeti National Park, Tanzania. These kills were often visited by scavengers, including relatively innocuous species such as vultures and jackals and potentially dangerous species, like spotted hyenas and lions. We used cheetah behavior at kills to test a number of predictions about how cheetahs should minimize risk at kill sites given they face an increased risk of predation of themselves or their cubs. In particular, we examined the propensity of cheetahs of different age/sex classes to hide carcasses after making a kill, vigilance at kills, and the delay in leaving after finishing feeding with respect to ecological factors and scavenger presence. The behavior of single females at kills did not suggest that they were trying to avoid being killed, but the behavior of males, often found in groups, was in line with this hypothesis. In contrast, the behavior of mother cheetahs at kills appeared to be influenced greatly by the risk of cubs being killed. Our results suggest that cheetahs use several behavioral counterstrategies to avoid interspecific predation of self or cubs. [ABSTRACT FROM AUTHOR]

In the framework of the EFESTUS project (funded by the European Commission, contract No. ICA3-CT-2002-10030) the corrosion products of a large number of archaeological bronze artefacts are investigated by means of the combined use of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and optical microscopy (OM) and tentative correlation of their nature with the chemical composition of the artefacts and the burial context is proposed. The results provide good insight into the corrosion layers and evidence in some bronze Roman coins and artefacts; the occurrence of uncommon corrosion phenomena that give rise to the formation of a yellowish-green complex chlorine-phosphate of lead (pyromorphite, (PbCl)Pb4(PO4)3) and of a gold-like thick layer of an iron and copper sulphide (chalcopyrite, CuFeS2). The micro-chemical and micro-structural results show that the coins were buried in a soil enriched in phosphorus for the accidental presence of a large amount of decomposing fragments of bones or in an anaerobic and humus rich soil where the chalcopyrite layer has been produced via the interaction between the iron of the soil, the copper of the coin and the sulphur produced by the decomposition of organic matter in an almost oxygen free environment. Finally, some unusual periodic corrosion phenomena occurring in high tin bronze mirrors found at Zama (Tunisia) are described. [ABSTRACT FROM AUTHOR]

A large number of Cu-based archaeological artefacts from the Mediterranean basin have been selected for investigation of their chemical composition, metallurgical features and corrosion products (i.e. the patina). The guidelines for the selection of the Cu-based artefacts have taken into account the representativeness of the Mediterranean archaeological context, the manufacturing technique, the degradation state and the expected chemical composition and structure of the objects. The results show wide variation of the chemical composition of the alloys that include all kinds of ancient Cu-based alloys such as low and high tin, and also leaded bronzes, copper and copper-iron alloys. The examination of the alloy matrix shows largely different metallurgical features thus indicating the use of different manufacturing techniques for producing the artefacts. The results of the micro-chemical investigation of the patina show the structures and the chemical composition of the stratified corrosion layers where copper or tin depletion phenomenon are commonly observed with a remarkably surface enrichment of some soil elements such as P, S, Ca, Si, Fe, Al and Cl. This information indicates the strict interaction between soil components and corrosion reactions and products. In particular, the ubiquitous and near constant presence of chlorine in the corrosion layers is observed in the patina of the archaeological Cu-based artefacts found in different contexts in Italy, Turkey, Jordan, Egypt, Spain and Tunisia. This latter occurrence is considered dangerous because it could induce a cyclic corrosion reaction of copper that could disfigure the artefact. The micro-chemical and micro-structural results also show that another source of degradation of the bronze archaeological artefacts, are their intrinsic metallurgical features whose formation is induced during the manufacturing of the objects, carried out in ancient times by repeated cycles of cold or hot mechanical work and thermal treatments. These combined treatments induce crystallisation and segregation phenomena of the impurities along the grain boundaries and could cause mechanical weakness and increase the extent of the inter-granular corrosion phenomena. [ABSTRACT FROM AUTHOR]

Within the framework of a project financially supported by the European Commission (contract Nr. 509126, acronym PROMET) the metallurgical techniques used by Romans and Greeks for coating the copper core of coins with a thin or thick layer of gold or silver are studied by means of the combined use of scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS) and optical microscopy (OM) techniques. This approach is utilised to gain further insight into the micro-chemical structure of the external regions of the coins as well as into the bulk metallurgical features. The results indicate that several methods were used by the Greek and Roman craftsmen including the mechanical application of a thin malleable gold or silver foils to be welded via thermal treatment. The analytical approach is also used for investigating the corrosion products grown on the coins during the long-term burial and for identifying degradation mechanisms. [ABSTRACT FROM AUTHOR]

Several common-use artifacts (coins, faience, cult objects, etc.) coming from two excavations sites near Rio de Janeiro, two sugar farms Historico do Rochedo and Cruzeiro, have been the subject of this investigation, which aimed to integrate physico-chemical characterizations with the identification of degradation mechanisms, and the proposal of innovative conservation methods, such as PECVD deposition of SiO2-like films for protection of metallic artifacts. For the microchemical, micromorphological and microstructural analysis, optical microscopy-OM, X-ray diffraction XRD, X-ray fluorescence-XRF, and scanning electron microscopy equipped with electron microprobe-SEM+EDS have been employed. A cleaning step followed by a consolidation step has been carried out on glassy artefacts, while on metallic artefacts the mechanical cleaning has been followed by a stabilization treatment when necessary. For long-term protection the deposition by PECVD of SiO2-like films has been performed on a series of copper-based alloys in a home made reactor fed with an tetraethoxysilane-oxygen-argon mixture. The coatings show a good barrier effect against the diffusion of water and oxygen from the environment to the metal surface, that increases with increasing the oxygen to monomer ratio in the feeding gas mixture and the input power density. Moreover, the coating adhesion increases if the deposition process is performed after a hydrogen plasma treatment. [ABSTRACT FROM AUTHOR]

Non-destructive testing methods are very important tools for conservators and art historians to obtain valuable information about works of art without causing any or even local damage to them. Two successful case studies showing the noticeable potentialities of two analytical portable instruments employed in the characterisation of tangible cultural heritage are shown. The first example concerns the chemical characterisation via an X-ray fluorescence (XRF) portable instrument of the red decorative pigment and of the stone surface of the Capestrano Warrior (Archaeological Museum of Chieti, Italy), which is considered the most important Italic stone statue found in Italy. The second concerns the use of a portable electrochemical impedance spectroscopy (EIS) measurement system for the characterisation of the protective effectiveness of the paints on the railing of Palazzo Reale in Torino, Italy. [ABSTRACT FROM AUTHOR]

In the framework of the PROMET project (European Commission contract No. 509126) aimed to develop new analytical techniques and materials for monitoring and protecting metal artefacts and monuments from the Mediterranean region, the corrosion products grown on silver Roman coins during archaeological burial is studied by means of scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and optical microscopy (OM) techniques. [ABSTRACT FROM AUTHOR]

The surface microchemical structure of high tin leaded bronze Roman mirrors has been studied by means of scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and optical microscopy (OM) techniques. The results allowed understanding of the origin of their high chemical stability and silvery-lustrous appearance. Indeed, some areas of the selected Roman mirrors are still characterised by a highly reflective and silver coloured surface even though they have been buried in the soil for about 2000 years. The micro-chemical results obtained from these areas have revealed that the mirror surface was tin enriched via inverse-segregation phenomenon by tailoring the cooling parameters. Furthermore, the presence of tin could be likely enhanced via cycles of oxidation and selective copper corrosion processes, thus resulting in a tin surface enrichment as a semi-transparent amorphous-like tin oxide (SnO2) film, as well as a copper depletion at the outer surfaces. [ABSTRACT FROM AUTHOR]

The bulk and surface chemical composition of Renaissance coins minted at Gubbio (Central Italy) from 1508 to 1516 and from 1521 to 1538 by Francesco Maria della Rovere is investigated by means of the combined use of different analytical techniques such as scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and optical microscopy (OM). The aim of the work is to determine the bulk chemical composition of these commonly used coins at Gubbio, to ascertain their surface nature and if they were coated by a thin film of silver or other white metals similar to silver. The results indicate that the coins were produced by coating a copper core with a thin film of silver and antimony, and also with lead whose thickness is of a few microns which is now scarcely present because the original silvered surface was almost entirely removed by degradation phenomena. Furthermore, the SEM+EDS results show that the surface content of silver and antimony cannot be attributed to long-term selective corrosion phenomena leaving the coin slightly silver or antimony enriched. Therefore, the presence of silver or apparently silver-like metals i. e. antimony and lead, could be considered as a deliberate surface finishing of the coins obtained via inverse segregation or intentional selective corrosion based on pickling solutions or a combination of them. From a historical point of view the presence of a Ag or Sb film on the surface of the coins discloses the occurrence of a period of economic difficulties. [ABSTRACT FROM AUTHOR]

By means of the combined use of glow discharge optical emission spectrometry (GDOES), scanning electron microscopy + energy dispersive spectrometry (SEM + EDS), X-ray diffraction (XRD) and optical microscopy (OM), corrosion products, i.e., the patina, grown on archaeological leaded bronze artefacts used by Punics and Romans, have been studied. This innovative approach has been utilised in order to gain further insight into the microchemical structure of the corrosion products as well as for selecting the cleaning and restoration methods. For all of the archaeological artefacts, the results show that via the innovative use of GDOES, it is possible to obtain reliable and reproducible quantitative elemental composition depth profiles for the outermost corroded layers, which are briefly discussed in combination with the microchemical features obtained via SEM + EDS, XRD and optical microscopy. Finally, the results show that GDOES, with its ability to provide routine and rapid analysis of layers of thickness up to 120 μm, seems to be a powerful technique in studies of the corrosion products on archaeological bronzes, with the aim of restoring and conserving ancient high tin or low tin leaded bronzes. [ABSTRACT FROM AUTHOR]

By means of the combined use of surface and micro-analytical techniques the surface chemical composition of ancient coins and some aspects of their manufacturing techniques and of degradation mechanisms have been elucidated. Two case histories are described concerning silver Roman Republican coins and some coins plated with thin films of silver and gold. In particular, the coinage methods, the silvering and gilding techniques and the origin of the embrittlement of these selected Roman coins have been studied by means of the combined use of selected-area X-ray photoelectron spectroscopy (SA-XPS) and scanning electron microscopy and energy-dispersive spectrometry (SEM+EDS). This innovative approach has been utilised in order to gain further insight into the microchemical structure of the external regions of the coins as well as of the bulk features. The results show the use of mercury to coat a copper or silver core with a thin film of precious metals that could be considered the most important advance in the technology of gilding to be made in antiquity. Furthermore, the microchemical investigation of brittle Roman silver coins has allowed us to identify the origin of this troublesome problem. The microchemical results indicate that brittleness is induced by the presence of a low amount of lead that is retained in supersaturated solution when the cast blank was produced. This latter element segregates at the grain boundaries during the coin production and the subsequent long-term ageing at room temperature, thus inducing the alloy fracturing along the weakened grain boundaries. [ABSTRACT FROM AUTHOR]

Using analyses that control for phylogeny, we examine whether the shapes of horns and antlers in ungulates are related to style of fighting, environmental factors, mating and social systems, or are simply arbitrary. Many of the predictions that relate horn shape to species' fighting tactics and to their mating and social systems are supported. Bovids with tips facing inwards are likely to wrestle with their horns, be monogamous and solitary, whereas those with tips facing out tend to be polygynous and live in large groups. Smooth horns are used for stabbing, and are found in females of polygynous species living in large groups. In female bovids, twisted horns are found in large species and are used in wrestling whereas, in male bovids, straight horns are found in solitary species. Finally, deer with more than five antler tines tend to be large and to fight by fencing. There was little support for shape of horns and antlers being related to environmental factors, nor were shapes arbitrary as might be expected if they had arisen through female choice. Body size had little effect on these results. In general, monogamous solitary bovids have straight inwardly facing horns whereas polygynous group-living species demonstrate a wide variety of horn shapes. [ABSTRACT FROM AUTHOR]