Microchemical Investigation of Long-Term Buried Gilded and Silvered Artifacts From Ancient Peru

A large number of metal artifacts with exceptional artistic value of the Moche culture have been found in the tombs of the Lords of Sipán (Lambayeque, Peru) and of the Lady of Cao (El Brujo, Peru) characterized by different burial conditions. Some of the objects, dated around 300–400 AD, are constituted by substrates of Cu- or Ag-based alloys coated by uniformly distributed thin films of precious metal (1–4 microns) that create also polymetallic bicolored surfaces with "gold" and "silver" areas. In order to investigate the corrosion product structure and composition as well as to identify the techniques used to give the gold or silver appearance, an integrated analytical approach has been adopted. The selected complementary methodologies were scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and optical microscopy (OM). The findings reveal that the substrates are mainly composed of Cu-Ag-Au alloys that at the site of Sipán have been almost completely corroded during the burial. Furthermore, the results show that the main aggressive agent is Cl– coming from the soil and that the degradation phenomena were likely enhanced by the galvanic coupling between the precious metal layer and the less noble substrate. The degradation products have formed mainly layered structures containing chloroargyrite (AgCl), cuprite (Cu2O), nantokite (CuCl), and atacamite [CuCl2.3Cu(OH)2] polymorphs. These latter species warn that dangerous copper cyclic corrosion is occurring, a harmful phenomenon, commonly defined as "bronze disease," which must be firmly mitigated. Finally, the findings reveal that the Moche metal workers used the depletion gilding to selectively modify the surface chemical composition of the artifacts to produce the Ag or Au thin films. According to this subtractive method, the surface of the Cu-Au-Ag alloys was enriched with a layer of precious metal by means of cycles of thermal treatments and removal of Cu or both Cu and Ag from the outermost region by using pickling solutions

Metals and Environment: Chemical Outputs From the Interaction Between Gilded Copper-Based Objects and Burial Soil

Three-dimensional chemical mapping was adopted to investigate an ancient fire-gilded buckle found in Rome. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were used to detect and locate degradation products aiming to identify the alteration processes. Inorganic and organic compounds present in the outermost part of such a class of cultural heritage objects can be considered the result of long-term interaction with the burial environment. ToF-SIMS depth profiling experiments can provide chemical information at the molecular level and high resolved spatial information (about 1 μm laterally, and 1 nm in depth). In this work, the attention was focused on the identification and localization of the ionic and molecular species involved in the degradation process. Results showed the presence of copper oxides, chlorides, and sulfides as common corrosion products but also the presence of species related to copper and bronze corrosion process such as atacamite and its polymorphs. 3D maps for all the relevant molecular species allowed to visualize at the same time the eruption of copper chlorides throughout the micro/nanochannels present on the gold surface, the recrystallization of compounds of minor elements from the substrate, a pathway followed by silico-aluminates from the surface towards the internal corrosion layers, but mostly the evidence of biological activity of Sulphur Reducing Bacteria (SRB) living in anaerobic conditions

Spectroscopic and Morphological Studies of Metal-Organic and Metal-Free Dyes onto Titania Films for Dye-Sensitized Solar Cells

We have investigated the spectroscopic behavior of three different sensitizers adsorbed onto titania thin films in order to gain information both on the electron transfer process from dye to titania and on the anchorage of the chromophore onto the semiconductor. We have examined by UV-Vis and fluorescence spectroscopy the widely used ruthenium complex cis-di(thiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II) (N719), the more recently developed organic molecular 3-(5-(4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acid (D5), and a push-pull zinc phthalocyanine sensitizer (ZnPc). Three type of titania films with different morphology, characterized by SEM and FT-IR measurement, were considered: a mesoporous transparent film deposited by spin-coating (TiMS), a semiopaque film deposited by doctor-blade from mesoporous titania (TiMS_DB) and a semiopaque film deposited by doctor-blade form commercial P25 titania (P25_DB). The use of TiMS is responsible for the adsorption of a higher amount of dye since the mesoporous structure allows increasing the interfacial area between dye and titania. Moreover, the fluorescence emission peak is weaker when the sensitizers are adsorbed onto TiMS. These findings suggest that mesostructured films could be considered the most promising substrates to realize photoanodes with a fast electron transfer process

Development and Implementation of the AIDA International Registry for Patients With Still's Disease

Objective: Aim of this paper is to present the design, construction, and modalities of dissemination of the AutoInflammatory Disease Alliance (AIDA) International Registry for patients with systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD), which are the pediatric and adult forms of the same autoinflammatory disorder. Methods: This Registry is a clinical, physician-driven, population- and electronic-based instrument implemented for the retrospective and prospective collection of real-world data. The collection of data is based on the Research Electronic Data Capture (REDCap) tool and is intended to obtain evidence drawn from routine patients' management. The collection of standardized data is thought to bring knowledge about real-life clinical research and potentially communicate with other existing and future Registries dedicated to Still's disease. Moreover, it has been conceived to be flexible enough to easily change according to future scientific acquisitions. Results: Starting from June 30th to February 7th, 2022, 110 Centers from 23 Countries in 4 continents have been involved. Fifty-four of these have already obtained the approval from their local Ethics Committees. Currently, the platform counts 290 users (111 Principal Investigators, 175 Site Investigators, 2 Lead Investigators, and 2 data managers). The Registry collects baseline and follow-up data using 4449 fields organized into 14 instruments, including patient's demographics, history, clinical manifestations and symptoms, trigger/risk factors, therapies and healthcare access. Conclusions: This international Registry for patients with Still's disease will allow a robust clinical research through collection of standardized data, international consultation, dissemination of knowledge, and implementation of observational studies based on wide cohorts of patients followed-up for very long periods. Solid evidence drawn from "real-life " data represents the ultimate goal of this Registry, which has been implemented to significantly improve the overall management of patients with Still's disease. NCT 05200715 available at

How metal-polymers interactions can affect the aesthetic features of protective coatings for artistic objects: the case of chitosan-based films

When new protective coatings for cultural heritage materials are developed, these need to be carefully validated on reference materials before the application on real artworks. Both protective properties and aesthetic requirements have to be satisfied when dealing with materials to be used on artistic objects. An easy and time-saving method used to evaluate such features is to submit reference samples to accelerated ageing treatments and to compare through time the behaviour of both coated and uncoated surfaces. However, accelerated degradation tests, which duration is usually no longer than a few months, are not suitable to monitor the long-term coatings behaviour. Interactions between the substrate and the protective film, as well as chemical or physical degradation of this latter, can indeed occur after a period of time longer than the one investigated by the accelerated ageing treatments. Studying long-term effects that can potentially compromise the protective and aesthetic properties of the coatings is thus mandatory when new conservative materials are developed. In this work, we propose an example of how short and long-lasting ageing tests might induce different treatment responses leading to an equivocal evaluation of the coating protective and aesthetic requirements. Chitosan-based coatings have been selected as green and eco-friendly materials for the protection of modern silver artifacts. They have been developed during the European Union’s project NANORESTART [1] and previously tested on copper-based alloys with promising results [2, 3]. Here, two different coatings formulations have been applied on sterling silver reference substrates and subjected to distinct ageing tests. These have been developed to simulate both a short-time exposure to a highly polluted environment and a long-time conservation in a real-like storage box. Optical microscopy (OM), electron scanning microscopy coupled with an energy dispersive spectrometer (FE-SEM-EDS) and UV-vis spectroscopy have been used to investigate the coatings’ physico-chemical properties, both before and after the tests. Differences in treatments’ response are related to the occurrence of short or long-term interactions between the metal substrate, the chitosan-based coatings and the environmental aggressive species. [1] H2020 NANORESTART project, “Nanomaterials for the restoration of works of art”, Grant Agreement n. 646063, http://www.nanorestart.eu [2] C. Giuliani, et al., Progress in Organic Coatings. 2018, 122, 138-146. [3] M. Salzano de Luna, et al., Angew. Chem. Int. 2018, 57, 1-6

Micro-structural and micro-chemical investigation of Samnite high-tin bronze cuirass discs: ancient metallurgy in central Italy

In the present study, micro-structural and micro-chemical investigation of archaeological bronze artefacts provided new insight about the metallurgical manufacture of defensive weapons by the Samnite’s metalsmiths in central Italy from the archaic necropolis of Barrea (AQ) and Torrebruna (CH). In particular, the metallurgical features, the chemical composition and the manufacturing process of Cu-based high-tin alloys used to produce cuirass discs were investigated. These artifacts were used to protect the warrior’s heart (i.e. the kardiophylaches) but were also and more importantly a distinctive sign of rank and role of warriors of the archaic age (VI BC). The Samnite cuirass discs are multi-material artifacts made of a decorated bronze central part with a complex metallurgical structure, due to the presence of different Cu-Sn phases, and a surrounding iron cladding to support the disk. These discs were studied by different surface and bulk techniques, namely Optical Microscopy (OM), Field Emission Scanning Electron Microscopy coupled with energy dispersive X-ray microanalysis (FE-SEM-EDS), X-ray Diffraction (XRD) and Infrared Spectroscopy (FTIR). The combined use of these techniques proved the high technological level of the Samnite metallurgists. In fact, their particular composition, having an uncommon high content of tin, made their manufacturing process difficult because of the intrinsic brittleness of the alloy. This work disclose the ability of Samnites people to successfully manipulate fragile high tin bronze alloys by inducing temporary phase changes and, thus, facilitating the mechanical shaping of the artifact

Micro-structural and micro-chemical composition of bronze artefacts from Tharros (Western Sardinia, Italy)

The present work reports the results of the SEM–energy dispersive spectrometry, X-ray diffraction (XRD), XPS and optical microscopy (OM) investigations performed to identify the corrosion products nature, i.e. the patina, grown on bronze common use artefacts found during excavations carried out at Tharros (on the west coast of Sardinia, Italy). The micro-chemical investigations of the patina revealed the structure and the chemical composition of the stratified corrosion layers, where tin depletion phenomenon has been observed within some cases of a surface enrichment of lead combined with elements coming from the soil such as Cl and P and mixed with other burial elements such as Ca, Si, Fe, Si and Al. The presence of soil elements was also confirmed by XPS investigations that evidence from the lineshape analysis and Binding Energy (BE) values of Cu 2p, Sn 3 d and Pb 4f photoemission signals that these elements are mainly present in their maximum oxidation states on the surface. The surface information is confirmed by OM and XRD results that evidence also the presence of copper rihydroxychlorides. In the inner layers, OM, SEM–energy dispersive spectrometry and XRD results disclose the presence of Cu (I) compounds such as cuprite (Cu2O) and nantokite (CuCl), the latter being the specie that induces the cyclic and self-sustaining degradation process commonly defined ‘bronze disease’. The micro-chemical and micro-structural informations demonstrate the strict interaction between soil components and corrosion products that form different compounds as a function of the local characteristics of the soil and of the chemical composition and metallurgical features of the Cu-based alloys