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This case study focuses on the reconstruction of the colour palette and the possibility of laser cleaning of burnt paintings. The paintings ORPHEUS IN THE UNDERWORLD and CONCORDIA, composed by the Greek artist Konstantinos Parthenis (1878–1967), have been severely damaged by fire. The colour palette of Parthenis is thoroughly investigated for the first time, and to perform this, a multi-analytical spectroscopic approach was employed. Non-destructive in situ analysis was performed on multiple areas of the paintings by portable XRF. SEM-EDS and Raman, supported by reflected visible light optical microscopy, and ultraviolet light microscopy, as well as structural XRD and molecular FTIR were performed for identifying the pigments, the binder and the substrate of the paintings. This work also unveiled new aspects of the painting technique used by the artist, such as the uncommon use of multiple pigments of red hue in the upper paint layers, comparatively with the rest of Parthenis' paintings. Molecular spectroscopic techniques ( i . e ., Raman and FTIR) were effective in identifying pigments like chrome yellow (crocoite mineral), chrome orange (phoenicochroite mineral) and viridian green (hydrated chromium oxide). The spectroscopic analyses were also essential in the laser cleaning restoration because of the detection of pigments ( i . e ., lead white, vermilion etc .) prone to phase transformations due to photothermal and/or photochemical effects. Our investigation establishes the basis on the application of non-conventional cleaning methods on damaged paintings, such as laser irradiation, in order to remove the damaged layer and/or the superficial accretions, while preserving the hues of the original painting. [ABSTRACT FROM AUTHOR]

Studies metallic photonic band-gap crystals operating in the microwave frequency range fabricated by laser precision machining. Composition of the crystals; Cutoff frequency exhibited; Defect modes created by combination of plates with different hole diameters.

Museum curators and archaeologists use analytical science to provide important information on artworks and objects. For example, scientific techniques provide information on artwork elemental composition, origin and authenticity, and corrosion products, while also finding use in the day-to-day conservation of many historical objects in museums and archaeological sites around the world. In this work two special cases are being discussed. In the first part of our work, physicochemical studies of an icon on a metal substrate were carried out using non-destructive, qualitative analysis of pigments and organic-based binding media, employing various microscopic and analytical techniques, such as Optical Fluorescence Microscopy, XRF, and Gas Chromatography. In the second part of our work, laser cleaning of late Roman coins has been performed using a Q-switched Nd:YAG laser (1064 nm, 6 ns) and a GaAlAs diode laser (780 nm, 90 ps). The corrosion products have been removed, while we observe increased concentrations in Ag, which is the main material of the silver plating found in late Roman coins. [ABSTRACT FROM AUTHOR]

Abstract: The surface of a typical Greek (Thassian) dolomitic marble was studied after interaction with U- and Th-containing aqueous solutions (1000mg/L, free-drift experiments for 1week at atmospheric ), using 12C-RBS and Laser μ-Raman spectroscopy. Powder-XRD and SEM-EDS were also applied to investigate the phases deposited on the surface of the interacted samples. The obtained results indicated a considerable removal of U from the aqueous medium mainly due to massive surface precipitation of amorphous UO2-hydroxide phases forming a relatively thick (μm-sized) coating on the carbonate substrate. The interaction of Th with dolomitic marble surface is also intense leading to a formation of an amorphous Th-hydroxide layer of similar thickness but of significantly lower elemental atomic proportion. [Copyright &y& Elsevier]

Abstract. Microcrystalline indium oxide (InO[sub x]) films with a crystallite size of 20.6 nm and a thickness of 100-1600 nm were prepared by dc reactive magnetron sputtering onto Corning 7059 glass substrates in various mixtures of oxygen in argon at room temperature. In a previous article, we have shown that the conductivity of these films can change in a controllable and fully reversible manner by about six orders of magnitude between an insulating and a very conductive state by alternately exposing the films to ultraviolet light (h nu is greater than or equal to 3.5 eV) in vacuum and reoxidizing them in ozone. In the present article, we report on studies of the surface and depth composition of these films carried out by Auger electron spectroscopy (AES), combined with depth profiling analysis. Quantitative Auger and energy-dispersive X-ray analysis (EDX) were employed to determine the stoichiometry of the films. The effects of film thickness and oxygen content during the deposition on the stoichiometry were examined. Both AES and EDX analysis confirmed that the stoichiometry is invariant for these growth conditions. The depth profiling analysis showed that all films exhibit extremely good in-depth uniformity, regardless of their thickness. [ABSTRACT FROM AUTHOR]

Abstract. The dynamics of the holographic recording in indium oxide (In[sub 2]O[sub 3]) thin films, grown by dc magnetron sputtering, using ultraviolet laser radiation at 325 nm, is investigated. Simultaneous measurements of the recording efficiency and electrical conductivity changes, under ambient conditions, prove that them is a strong relation between the two actions, and measurements of the recording efficiency with respect to the film conductivity history and temperature provide evidence for the presence of two coexisting processes in the recording regime. The reported results provide essential information on the mechanism and nature of holographic recording in this material. [ABSTRACT FROM AUTHOR]

A ~2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation ( IF) comparable to Precambrian banded iron formations ( BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a ~5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF ( CIF). Bulk δ13C isotopic compositions lower than -25‰ provide evidence for biological contribution by the Calvin and reductive acetyl-CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of ~0.04 wt.% combined with δ34S estimates of up to ~18‰ point to a non-sulphidic depository. Positive δ30Si records of up to +0.53‰ in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative δ30Si data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs. [ABSTRACT FROM AUTHOR]

Controlling the structure of hydroxyapatite nanocrystals is vital for acquiring a consistent product. In an effort to synthesize crystals mimicking the morphology of natural bone's apatite, a bioinspired process was developed based on the use of a natural biomacromolecule, collagen or chitosan, in conjunction with l -arginine to direct the formation of hydroxyapatite from H 3 PO 4 and Ca(OH) 2 . Different cases were investigated by employing various concentrations of the precursors and two molar ratios of Ca/P 1/1 and 10/6. The reaction was carried out at basic pH conditions and at biomimetic temperature (40 °C). The resulting aqueous suspensions were characterized in terms of their rheological behavior, whereas the derived powders were fully evaluated by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis and Raman spectroscopy. The analysis showed that in all cases, the only phase detected was hydroxyapatite of a plate-like morphology very similar to that of natural apatite. The homogeneity of the morphology and the crystal size distribution depend on the precursors' final concentration with the mean size ranging from 5 nm up to 20 nm. The powder that demonstrated the best characteristics in terms of homogeneity was that produced in the presence of collagen for molar ratio of Ca/P 1/1. [ABSTRACT FROM AUTHOR]

Abstract: Pure metallic Pb foils were exposed to the atmosphere of Athens for different periods of time (up to 150 non-rainy days) in the summer of 2005. The interacted Pb surfaces were probed using the 12C(d,p)13C reaction (E d: 1100keV) at the Tandem accelerator of the NCSR “DEMOKRITOS”. Laser-μRaman and SEM–EDS were also complementary applied. Using the above methodology we recorded surface carbon profiles and concentrations as a function of the exposure time, corresponding to the evolution of the carbonate layer formed onto Pb foils due to the interaction with atmospheric H2O and CO2. The C-containing surface layer was found to be stabilized after ∼120days. Further investigation by means of laser-μRaman and SEM–EDS indicated that the patina initially consists of Pb-hydroxycarbonates (hydrocerussite) overgrowing Pb-oxides, whereas Pb-sulfates (anglesite) and possibly basic Pb-sulfates are formed at the end of the patination process. The crystal growth of Pb-sulfates, or most likely the transformation of hydroxycarbonates to sulfates, is attributed to the pollution of Athens atmosphere by SO2. [Copyright &y& Elsevier]

Corrections to the article "Optical tweezers with enhanced efficiency based on laser-structured substrates" that was published in the 2012 issue are presented.

We present an optical nanotrapping setup that exhibits enhanced efficiency, based on localized plasmonic fields around sharp metallic features. The substrates consist of laser-structured silicon wafers with quasi-ordered microspikes on the surface, coated with a thin silver layer. The resulting optical traps show orders of magnitude enhancement of the trapping force and the effective quality factor. [ABSTRACT FROM AUTHOR]