What is the origin of the black film in the sculpture “Death of Cleopatra”?

This work arises from the need to identify the origin of a black film which is currently covering a large area of the sculpture DeathofCleopatra, promoting its disfiguration. This piece, sculpted in Carrara marble, belongs to Tropical Botanic Garden, in Lisbon. In situ works involved colorimetric measurements, adhesion tests and mapping of decay patterns. Samples of the black film were taken from the sculpture and also from black areas present in botanic species surrounding the sculpture, which were observed macro and microscopically. Individual samples of the black film were analysed by Fourier-transform infrared spectroscopy. The results obtained show the collected samples possess saccharides such as sucrose, found in honeydew exemplars. Therefore, it is proposed that black film formation is due to sooty mould. This black film is responsible for aesthetic damage, as well as stone corrosion processes, which was observed by scanning electron microscopy.publishersversionpublishe

Biodiversity of cyanobacteria and green algae on monuments in the Mediterranean Basin: an overview

Microbiology (2009), 155, 3476–3490The presence and deteriorating action of micro-organisms on monuments and stone works of art have received considerable attention in the last few years. Knowledge of the microbial populations living on stone materials is the starting point for successful conservation treatment and control. This paper reviews the literature on cyanobacteria and chlorophyta that cause deterioration of stone cultural heritage (outdoor monuments and stone works of art) in European countries of the Mediterranean Basin. Some 45 case studies from 32 scientific papers published between 1976 and 2009 were analysed. Six lithotypes were considered: marble, limestone, travertine, dolomite,sandstone and granite. A wide range of stone monuments in the Mediterranean Basin support considerable colonization of cyanobacteria and chlorophyta, showing notable biodiversity. About 172 taxa have been described by different authors, including 37 genera of cyanobacteria and 48 genera of chlorophyta. The most widespread and commonly reported taxa on the stone cultural heritage in the Mediterranean Basin are, among cyanobacteria, Gloeocapsa, Phormidium and Chroococcus and, among chlorophyta, Chlorella, Stichococcus and Chlorococcum. The results suggest that cyanobacteria and chlorophyta colonize a wide variety of substrata and that this is related primarily to the physical characteristics of the stone surface, microclimate and environmental conditions and secondarily to the lithotype

Characterization of Microbial Communities Associated with Ceramic Raw Materials as Potential Contributors for the Improvement of Ceramic Rheological Properties

Technical ceramics are being widely employed in the electric power, medical and engineering industries because of their thermal and mechanical properties, as well as their high resistance qualities. The manufacture of technical ceramic components involves complex processes, including milling and stirring of raw materials in aqueous solutions, spray drying and dry pressing. In general, the spray-dried powders exhibit an important degree of variability in their performance when subjected to dry-pressing, which affects the efficiency of the manufacturing process. Commercial additives, such as deflocculants, biocides, antifoam agents, binders, lubricants and plasticizers are thus applied to ceramic slips. Several bacterial and fungal species naturally occurring in ceramic raw materials, such as Sphingomonas, Aspergillus and Aureobasidium, are known to produce exopolysaccharides. These extracellular polymeric substances (EPS) may confer unique and potentially interesting properties on ceramic slips, including viscosity control, gelation, and flocculation. In this study, the microbial communities present in clay raw materials were identified by both culture methods and DNA-based analyses to select potential EPS producers based on the scientific literature for further assays based on the use of EPS for enhancing the performance of technical ceramics. Potential exopolysaccharide producers were identified in all samples, such as Sphingomonas sp., Pseudomonas xanthomarina, P. stutzeri, P. koreensis, Acinetobacter lwoffi, Bacillus altitudinis and Micrococcus luteus, among bacteria. Five fungi (Penicillium citrinum, Aspergillus niger, Fusarium oxysporum, Acremonium persicinum and Rhodotorula mucilaginosa) were also identified as potential EPS producers.Fundação para a Ciência e a Tecnologia-EXPL/CTM-CER/0637/201

Marmoreados da Igreja São Luís dos Franceses (Lisboa): estado de conservação, caracterização das argamassas e da camada pictórica

This article makes known the research on the internal wall renders of the Church São Luís dos Franceses, with paintings on the stucco imitating marble, the so-called faux marble. They have been executed between 1766 and 1769. The study characterizes the faux marble, performed by the technique Stucco Lustro. In this context, we examined their condition and characterized this covering, using several analytical techniques. The results were discussed in the light of traditional recipes on the production of faux marble paintings in walls.Este estudio se refiere a la labor de investigación llevada a cabo en el revestimiento de las paredes interiores de la Iglesia de São Luís dos Franceses, en falso estuco imitando mármol, hechos entre 1766 a 1769. El estudio caracteriza el marmoleado, realizado por la técnica de “Stuco Lustro”. En este contexto, se analizó su estado de conservación y procedió a caracterización de este revestimiento, utilizando varias técnicas de analíticas. Los resultados también fueron discutidos a la luz de la documentación histórica acerca de las técnicas tradicionales de la pintura sobre falso estuco.Este estudo refere-se ao trabalho de investigação do revestimento das paredes interiores da Igreja São Luís dos Franceses, pintura de fingidos sobre estuque, os marmoreados, que terão sido executados entre 1766 a 1769. O estudo caracteriza os marmoreados, executados pela técnica Stucco Lustro. Neste contexto, foi analisado o seu estado de conservação e procedeu-se à caracterização deste revestimento, com recurso a diversas técnicas laboratoriais. Os resultados obtidos foram ainda discutidos à luz da documentação histórica existente sobre as técnicas tradicionais de pintura de fingidos sobre estuque

The influence of inherent properties of building limestones on their bioreceptivity to phototrophic microorganisms

Annals of Microbiology, 59 (4) 705-713 (2009)The influence of open porosity, water absorption capillarity, water vapour permeability, surface roughness, stone pH and chemical composition on stone bioreceptivity to phototrophic microorganisms was assessed by means of a thorough stone characterisation with subsequent artificially inoculation of limestone samples with a multi-species phototrophic culture and placing them inside a growth chamber for 90 days. A principal component analysis and an analysis of variance(ANOVA) were carried out in order to evaluate the direct relationships between stone bioreceptivity and petrophysical properties. From the principal component analysis, two main components were obtained and assigned a petrophysical/photosynthetic biomass meaning. Stone bioreceptivity, quantified by the amount of chlorophyll a and intensity of chlorophyll a fluorescence present on the stone samples after 90 days-incubation, was included in both principal components. The first component was linked to the amount of chlorophyll a and was highly and linearly associated to capillarity and roughness,and less associated with open porosity and water vapour permeability. The second component, linked to the intensity of chlorophyll a fluorescence measured on the stone surfaces, was not linearly associated with the petrophysycal properties,showing the fallibility of this in vivo chlorophyll quantification technique on the estimation of photosynthetic biomass growing on stone materials, particularly when endolithic growth occurs

Growth of phototrophic biofilms from limestone monuments under laboratory conditions

International Biodeterioration & Biodegradation,xxx (2009) 1–8In the current study, five phototrophic biofilms from different Southern Europe limestone monuments were characterised by molecular techniques and cultivated under laboratory conditions. Phototrophic biofilms were collected from Orologio Tower in Martano (Italy), Santa Clara-a-Velha Monastery and Ajuda National Palace, both in Portugal, and Seville and Granada Cathedrals from Spain. The biofilms were grown under laboratory conditions and periodically sampled in order to monitor their evolution over a three-month period. Prokaryotic communities from natural samples and cultivated biofilms were monitored using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments in conjunction with clone sequencing and phylogenetic analysis. DNA-based molecular analysis of 16S rRNA gene fragments from the natural green biofilms revealed complex and different communities composition with respect to phototrophic microorganisms. The biofilms from Orologio Tower (Martano,Italy) and Santa Clara-a-Velha Monastery (Coimbra, Portugal) were dominated by the microalga Chlorella. The cyanobacterium Chroococcidiopsis was the dominating genus from Ajuda National Palace biofilm(Lisbon, Portugal). The biofilms from Seville and Granada Cathedrals (Spain) were both dominated by the cyanobacterium Pleurocapsa. The DGGE analysis of the cultivated biofilms showed that the communities developed differently in terms of species establishment and community composition during the threemonth incubation period. The biofilm culture from Coimbra (Portugal) showed a remarkable stability of the microbial components of the natural community in laboratory conditions. With this work,a multiple-species community assemblage was obtained for further stone colonisation experiments

Reproducing stone monument photosynthetic-based colonization under laboratory conditions

Science of the total environment 405(2008) 278-285In order to understand the biodeterioration process occurring on stone monuments, we analyzed the microbial communities involved in these processes and studied their ability to colonize stones under controlled laboratory experiments. In this study, a natural green biofilm from a limestone monument was cultivated, inoculated on stone probes of the same lithotype and incubated in a laboratory chamber. This incubation system, which exposes stone samples to intermittently sprinkling water, allowed the development of photosynthetic biofilms similar to those occurring on stone monuments. Denaturing gradient gel electrophoresis (DGGE) analysis was used to evaluate the major microbial components of the laboratory biofilms. Cyanobacteria, green microalgae, bacteria and fungi were identified by DNA-based molecular analysis targeting the 16S and 18S ribosomal RNA genes. The natural green biofilm was mainly composed by the Chlorophyta Chlorella, Stichococcus, and Trebouxia, and by Cyanobacteria belonging to the genera Leptolyngbya and Pleurocapsa. A number of bacteria belonging to Alphaproteobacteria, Bacteroidetes and Verrucomicrobia were identified, as well as fungi from the Ascomycota. The laboratory colonization experiment on stone probes showed a colonization pattern similar to that occurring on stone monuments. The methodology described in this paper allowed to reproduce a colonization equivalent to the natural biodeteriorating process

Assessing Water Resistance and Surface Properties of ETICS

External Thermal Insulation Composite Systems (ETICS) contribute significantly to building energy efficiency by increasing thermal insulation, correcting thermal bridges and reducing interior water condensation. Additionally, these solutions protect the structure and thus enhance the durability of the building. The use of ETICS remarkably increased in the last three decades also due to the introduction of new international and national regulations on building energy efficiency (e.g. EU Directive on the Energy Performance of Buildings). ETICS are constantly exposed to weathering (e.g. wind, rain, sun light) and anthropic factors (e.g. graffiti, environmental pollutants), which can lead to cracks, biocolonization and stains and thus affect ETICS durability. However, international technical documents on the evaluation of the effectiveness and durability of ETICS do not consider the possible synergies between these factors, which can trigger and speed up multiple biological, mechanical and chemical degradation processes. With the aim of filling this gap, this paper focused on the water resistance and surface properties of several ETICS surface coatings, verifying possible connections between these factors. The moisture transport properties (capillary water absorption, water vapour permeability, and drying kinetics) and surface properties (colour, brightness and roughness) of some commercially available ETICS were tested. This study is part of a wider research project (WGB_Shield: resistance for water, graffiti and biocolonization of external thermal insulation systems) that aims at the development of ETICS with improved durability in urban environment

À Descoberta do "Ouro Branco"

UIDB/00417/2020 UIDP/00417/2020Caderno pedagógico sobre mármores realizado no âmbito do projecto PHIM - Património e História da Indústria dos Mármores [ALT20-08-2114-FEDER-000213].publishersversionpublishe