Metabolomic Profiling of Biolayers on the Surface of Marble in Nature and Urban Environment. Case Study of Karelia and St. Petersburg

The formation of biolayers of various taxonomic and biochemical composition occurs on the rock surfaces under various environmental conditions. The composition of metabolites in various types of biolayers on the marble surface in natural outcrops and urban environment was studied. Metabolome profiling was fulfilled by GC-MS. It was found that communities in urban environment are much less biochemically diverse than in a quarry. The seasonal differences in metabolite network between samples dominate over taxonomic ones in biolayers with predomination of algae and cyanobacteria and in biolayers with predomination of fungi. The biolayers of different stage of soil formation are less susceptible to seasonal variability.

An Interpretation and Analysis on the Polychromy of Attic Korai from Votive and Funerary Contexts

The characteristic woman of Archaic Greek sculpture, the kore (pl. korai) stands proud, rigid, frontal, and omnisciently smirking at her viewer with the famous Archaic smile. She has been interpreted as an attendant, goddess, or deceased maiden, wearing representations of draped diaphanous robes, jewelry, and bearing offerings. Yet where her now clean marble surface exists once was intricately illuminated with vibrant pigments, inlaid stones, metals, and often accompanied by accessories of various materials. Recent advancements in analytical techniques have enabled scholars to delve deeper into the study of these sculptures, uncovering traces of pigments which would otherwise be left undetected. However, the image that these colours paint has yet to be thoroughly analysed and a history of intentional removal and surface cleaning has postponed a complete evaluation of the sculptures. In Attica, from the sixth to the early 5th century BCE, korai reflect stylistic progression and variation within and between archaeological contexts. A palette of colours was used to display features now lost to the modern eye. This paper examines the korai, proposing meaning through colour, patterns, and representations. Using polychrome reconstructions, spectral data, pottery, archaeological evidence, and ancient literary sources, the author interpreted the polychromy and decorative elements of Attic korai from votive and funerary contexts. Asking questions on symbolism, utility, cultural connection, and identity of the sculptures; this paper explains the use of pigments in relation to the symbolism of the sculptures and to their role in the greater framework of the Archaic Greek world.

The Friction Angle of the Leiyang Marble Surface after Exposure to High Temperature

There is a lack of information about the temperature-dependent nature of the rock surface, which is one of the essential parameters to predict the surface friction. In the present study, we experimentally study the effect of temperature on the basic friction angle of the marble surface through the direct shear test under the low normal loading condition and tilting test (Stimpson/disk tilt test). The basic friction angle gradually decreases with the increase in temperature from 20°C to 600°C for the two kinds of the tilting test. The results indicate that the Stimpson test on samples with the length-to-diameter ratio of 2 can be more reliable to estimate the basic friction angle of the rock surface after exposure to high temperatures. The results illustrate that the sliding angle depends on the surface condition. With the increase in the repetitive measurements, the sliding angle decreases as the marble surface is cleaned, and the parameter increases as the marble surface is not cleaned.

STATISTICAL MODELS OF THE METABOLOME OF LITHOBIONTIC COMMUNITIES IN NATURAL AND URBANIZED CONDITIONS

The composition of metabolites in various types of biolayering on the marble surface in natural outcrops and in an urban environment has been studied. Metabolomic profiling was performed by gas chromatographymass spectrometry. It was found that biolayering in the urban environment is much less diverse biochemically than in anthropogenically undisturbed conditions. The differences in metabolomic data were significantly greater between sampling sites than between community types. Lithobiontic communities of organisms are an interesting and promising for bioindication and biomonitoring of the environment.

Olympian Jupiter. Winckelmann and Quatremère de Quincy on Ancient Polychromy

A number of Western museums may boast of their important collections of Classical Greek and Roman art. Marble statues of deities or heroes from Classical Antiquity, and important works in painting and architecture from different historical epochs, have traditionally made up the canon of Western art. In recent years, critics have claimed that this tradition represents an idealisation of the white, Caucasian body type which excludes other races from the concept of beauty. Although we today know that ancient statues in marble were often painted in vivid colours, they say that art theorists have either been ignorant of, or glossed over, this fact. While the German art historian Johann Joachim Winckelmann has often been regarded as a proponent of our Western predilection for whiteness, the French archaeologist Antoine Chrysostome Quatremère de Quincy is by many celebrated as the first to realise the extent and importance of ancient polychromy. In this paper, I will try to show that this is a distorted view, especially where Winckelmann’s theories are concerned. Far from being ignorant about ancient polychromy, Winckelmann was an important source for Quatremère de Quincy. In addition, Winckelmann’s appreciation of the white marble surface was not the result of racial prejudice, but the expression of an aesthetic opinion that he shared with Quatremère de Quincy.

Electrodeposition of Hydroxyapatite Coatings for Marble Protection: Preliminary Results

Surface coatings made of hydroxyapatite (HAP) have been proposed to protect marble artworks from dissolution in rain, originated by the aqueous solubility of calcite. However, HAP coatings formed by wet chemistry exhibit incomplete coverage of marble surface, which results in limited protective efficacy. In this study, electrodeposition was explored as a new route to possibly form continuous coatings over the marble surface, leaving no bare areas. Electrodeposition was performed by placing marble samples in poultices containing the electrolyte (an aqueous solution with calcium and phosphate precursors) and the electrodes. The influence of several parameters was investigated, namely the role of the working electrode (cathode or anode), the distance between the marble sample and the working electrode, the deposition conditions (potentiostatic or galvanostatic), the electrolyte composition and concentration, the applied voltage, and time. The coating morphology and composition were assessed by SEM/EDS and FT-IR. The protective ability of the most promising formulations was then evaluated, in all cases comparing electrodeposition with traditional wet synthesis methods. The results of the study suggest that electrodeposition is able to accelerate and improve formation of HAP coatings over the marble surface, even though the obtained protective efficacy is not complete yet.

Microemulsion Encapsulated into Halloysite Nanotubes and their Applications for Cleaning of a Marble Surface

Halloysite nanotubes were used to incorporate anionic surfactant micelles and an organic solvent to generate a cleaning system to be applied in Cultural Heritage restoration. The targeted adsorption is driven by electrostatic interactions based on the nanotubes peculiar charge separation. Namely anionic species are driven to the positively charged inner surface while being prevented from interacting with the halloysite outer surface that possesses a positive charge density. The hybrid organic/inorganic emulsion was characterized by dynamic light scattering. Analysis of the autocorrelation function allowed us to define the presence of surfactant aggregates inside/outside the nanotube lumen as a function of the nanotube/surfactant ratio in an aqueous mixture. The application of this prepared emulsion for the controlled cleaning of a marble artifact is demonstrated. To this purpose, a membrane of nanofibrous polyacrylonitrile was prepared by electrospinning and was applied between the work of art and the cleaning agent to avoid the release of residues on the marble surface. This work represents a further step toward the opportunity to extend the use of emulsions for cleaning protocols for stone-based artifacts or in technological applications where surfactant separation is required by a simple centrifugation/sedimentation method.

Marble Slabs Classification System Based on Image Processing (Ark Marble Mine in Birjand)

Marble is one of the semi-precious stones that has been used in decorating building façade and making decorative things. This stone is present in the nature in the form of rock or layered stone. Examining the kind of stone, extent of impurity and different streaks in white marble is a widely confronted subject by those who are involved in this industry. Obtaining the extent of impurity of white marble using methods of detecting and analyzing material is expensive and time-consuming. In this research carried out on while marbles of Arc Mine in Birjand, it has been attempted to present very fast method using Image Processing Techniques so that while preserving identity and appearance of stone and without any damage to it, we compute the impurity level and different streaks on white marble surface. The proposed method includes two stages; in the first stage applying image processing functions, it is attempted to segment the present impurities and streaks on marble surface from the stone background and in the second stage, the area of these impurities and streaks is computed. Results obtained in this paper (97.8%) in comparison with other researches and experimental methods indicate acceptability of this algorithm.