Time filter

Source Type

Chalkidiki, Greece

Matziaris K.,Aristotle University of Thessaloniki | Stefanidou M.,Aristotle University of Thessaloniki | Karagiannis G.,Art Diagnosis Center
Progress in Organic Coatings | Year: 2011

The imperative needs of energy saving during the latest years indicate the necessity of producing hydrophobic building materials in order to increase their durability. In the frame of this experimental work, low-fired clay (roof tiles and facing bricks) have been subjected to impregnation to make them water-repellent. To achieve this, water- and solvent-based silanes/siloxanes have been selected enriched with Si nanoparticles. Generally the mechanism of these coatings is to reduce the water capillary absorption of the building materials which has penetrated, but does not clog pores or capillaries, therefore little or no impairment of the building material's ability to "breathe". Different tests have been performed in the laboratory in order to test the efficiency of the tested solutions such as capillary elevation and water absorption. Additional the measurement and the evaluation of the thickness and the retention of the applied coating on the LFCM were performed using acoustic microscopy. This evaluation can be made in a repetitive way during the lifetime of the material targeting to the continuous monitoring of this effect. © 2011 Elsevier B.V. All rights reserved.

Sotiropoulou S.,Art Diagnosis Center | Papliaka Z.E.,Elettra - Sincrotrone Trieste | Vaccari L.,Elettra - Sincrotrone Trieste
Microchemical Journal | Year: 2016

This work deals with the detection and imaging of metal oxalates/carboxylates in the paint layers of ancient wall paintings and with the investigation of their possible association with the ageing of organic substances used as binding media in the original painting. This assumption is investigated employing Fourier transform infrared (FTIR) imaging on several case studies; starting with a thin section of the paint stratigraphy extracted from extensively deteriorated post-Byzantine murals, painted with an oil binder. Metal carboxylates and oxalates show their maximum concentration at the interface of free fatty acids and pigment particles, indicating a possible origin of their formation. Then, the methodology was applied in paint thin sections, originating from Prehistoric, Roman and Hellenistic wall paintings. In these case studies, metal oxalates detected within the paint layers were explored regarding their relation to the use of an organic binder in the wall paintings. The chemical images of calcium oxalates in the paint layers of the Prehistoric wall paintings was a trigger for further laborious investigation on numerous samples, which resulted in revealing the spectrum of an aged proteinaceous binding medium. Thereafter, the distribution of metal oxalates within the paint layers of the samples from the Roman and Hellenistic wall paintings, unaffected by any later intervention, was assumed as an indirect indication of the use of an original organic binder. © 2015 Elsevier B.V.

Stefanidou M.,Aristotle University of Thessaloniki | Matziaris K.,Aristotle University of Thessaloniki | Karagiannis G.,Art Diagnosis Center
Geosciences (Switzerland) | Year: 2013

Modern sustainable architecture indicates the use of local natural stones for building. Greek sandstones from Epirus (Demati, Greece, EN 12440) used as building facades meet aesthetic and have high mechanical properties, but the inevitable interaction between stone materials and natural or anthropogenic weathering factors controls the type, and extent of stone damages. In the present paper, samples of sandstone were treated with a conventional hydrophobic product and four solutions of the same product, enriched with nanosilica of different concentrations. The properties of the treated samples, such as porosity and pore size distribution, microstructure, static contact angle of a water droplet, and durability to deterioration cycles (freeze-thaw) were recorded and conclusions were drawn. The research indicates the increased hydrophobic properties in nanosilica solutions but also the optimum content in nanoparticles that provides hydrophobicity without altering the properties of the stone. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Karapanagiotis I.,Heritage University | Mantzouris D.,Art Diagnosis Center | Cooksey C.,59 Swiss Avenue | Mubarak M.S.,University of Jordan | Tsiamyrtzis P.,Athens University of Economics and Business
Microchemical Journal | Year: 2013

The efficiencies of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and pyridine to treat and solubilise Tyrian purple are compared using high performance liquid chromatography (HPLC). For the comparative study, samples of Hexaplex trunculus, collected from the area of Carthage, are treated with the three solvents and the following compounds are monitored with HPLC: indigotin, indirubin, 6'-bromoindirubin, 6-bromoindirubin, 6-bromoindigotin, 6,6'-dibromoindigotin and 6,6'-dibromoindirubin. HPLC identifications are achieved as these compounds were synthesized in pure forms and characterized using 1H NMR, elemental analyses and IR spectroscopy. It is shown that pyridine results in poor yields compared to the quantities solubilised using DMF or DMSO. However, the relative composition of the purple dye is not affected by the solvent used for sample treatment. DMSO resulted in improved HPLC signals (peak heights) over DMF and is therefore selected for further studies. The effects of treatment temperature and time are investigated, suggesting that the best conditions correspond to 80°C and 15min.The improved method (treatment with DMSO at 80. °C for 15. min) is used to treat more molluscan samples which are then subjected to HPLC analysis. The results are investigated in the light of previously collected (published and unpublished) analytical data. In particular, principal component analysis (PCA) is applied, to investigate if it is possible to achieve a distinction between the three Mediterranean molluscan species (H. trunculus L., Bolinus brandaris L. and Stramonita haemastoma), using all the HPLC quantitative results reported up until now by various researchers. The PCA plot shows that B. brandaris and S. haemastoma species are not separated and H. trunculus samples are slightly separated from the other two species.The above findings are used to investigate the possible biological origin of Tyrian purple detected in historical -initially studied using X-ray fluorescence spectroscopy- and archaeological samples. Furthermore, the improved method, devised herein, resulted in the identification of monobromoindirubins in the DMSO extracts of the archaeological samples, which were not detected in previous studies where DMF was used to treat the same significant samples. © 2013 Elsevier B.V.

Papadopoulou S.K.,Aristotle University of Thessaloniki | Dritsas G.,Aristotle University of Thessaloniki | Karapanagiotis I.,Art Diagnosis Center | Zuburtikudis I.,TEI of Western Macedonia | Panayiotou C.,Aristotle University of Thessaloniki
European Polymer Journal | Year: 2010

A fluorinated methacrylic homopolymer, poly(2,2,3,3,3-pentafluoropropyl methacrylate) (PPFPMA) was synthesized by a free radical polymerization reaction. The dispersive component of the surface energy (γsd) of PPFPMA was determined by contact angle measurements and inverse gas chromatography (IGC). An extensive surface characterization was conducted by means of IGC. Surface characterization demonstrated that PPFPMA has low γsd value, even at 35 °C and is a Lewis amphoteric polymer with predominantly basic character, as confirmed by the Lewis acidity and basicity constants KA and KB, respectively. The values of γsd obtained by IGC are slightly higher than those obtained by the contact angle method. This trend can be attributed to the fact that IGC evaluates, primarily, high energy sites of a surface. © 2009 Elsevier Ltd. All rights reserved.

Discover hidden collaborations