4 Material und Umwelt
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Eingeladener Vortrag
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The initial focus of this research was on the development of a general workflow for the documentation and monitoring of historical stained glass windows using structured light scanning.
Therefore windows from different churches, time periods and with different corrosion and damage phenomena were scanned before and after conservation measures.
The initial focus of this research was on the development of a general workflow for the documentation and monitoring of historical stained glass windows using structured light scanning. Therefore windows from different churches, time periods and with different corrosion and damage phenomena were scanned before and after conservation measures. To evaluate the execution of the restoration measures the data was compared using 3D inspection software to examine the differences in geometry between the two scans. Various problems had to be solved, for example, how to deal with heavily reflective surfaces and the extreme contrast between light and dark surfaces, as seen in the borders between ‘Schwarzlot’ painting and plain glass. The application of materials for matting the surfaces, such as Cyclododecane spray, was impossible due to the high accuracy of the surface measurement required for 3D inspection. Regarding the contrast differences of the surfaces, the creation of exposure fusions and the use of polarization filters to reduce reflections were tested. In addition to the general problems encountered when recording translucent surfaces, the historical glasses caused additional problems in calculating surface comparisons. For example, the windows have to be moved and turned around several times, both during the conservation process and while scanning, causing deformations of the geometry due to the flexible lead rods allowing a certain degree of movement.
In this poster we will present some results of a research projects dealing with Arabic recipes of black inks. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed.
We will show procedures and problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on squid ink and mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol, the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts.
In this poster we will present some results of a research projects dealing with Arabic recipes of black inks. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed.
First, we will provide an overview of the sources [1-2] employed in the study – dating from 9th to 14th century, although the manuscripts in which they can be found dates up to the 20th century – with an eye on the ink typologies (real and perceived by the compilers). Then we will show how, by reproducing the recipes, it was possible to shed light on some oddities in the procedures and the choice of ingredients. In the end we will discuss problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect [3]. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol and the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts.
[1] A. Schopen, Tinten und Tuschen des arabisch-islamischen Mittelalters, Göttingen: Vandenhoeck & Ruprecht, 2004
[2] S. Fani, Le arti del libro secondo le fonti arabe originali. I ricettari arabi per la fabbricazione degli inchiostri (sec. IX-XIII): loro importanza per una corretta valutazione e conservazione del patrimonio manoscritto, PhD thesis, Napoli: Università L’Orientale, 2013
[3] C. Colini et. al, Manuscript cultures, 11 (2018) 43-50
In this poster we will present some results of a research projects dealing with Arabic recipes of black inks [1-2]. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed.
We will show procedures and problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on squid ink [3] and mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect [4]. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol, the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts.
[1] A. Schopen, Tinten und Tuschen des arabisch-islamischen Mittelalters, Göttingen: Vandenhoeck & Ruprecht, 2004
[2] S. Fani, Le arti del libro secondo le fonti arabe originali. I ricettari arabi per la fabbricazione degli inchiostri (sec. IX-XIII): loro importanza per una corretta valutazione e conservazione del patrimonio manoscritto, PhD thesis, Napoli: Università L’Orientale, 2013
[3] S. Centeno, J. Shamir Journal of Molecular Structure, 873 (2008), 149-159
[4] C. Colini et. al, Manuscript cultures, 11 (2018) 43-50
This work addresses the identification of synthetic organic pigments (SOP) in ten modern reverse paintings on glass (1912-1946) by means of an in-situ multi-analytical approach. The combination of the complimentary properties of mobile Raman spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) enabled the detection of sixteen SOP even in complex mixtures with inorganic compounds and binders. For the β-naphthol pigments, both Raman and DRIFTS yield appropriate results. DRIFTS was the preferred method for the detection of synthetic alizarin (PR83). Its diagnostic band pattern even allows its detection in complex mixtures with mineral pigments, binders and fillers. Raman spectroscopy yielded distinctive spectra for the triaryl carbonium pigments (PG1, PV2, PR81) and the two-yellow azo SOP (PY3, PY12), whereas DRIFT spectra were affected by extensive band overlapping. This may also occur in Raman spectra, but in less problematic amounts. Fluorescence is the major problem with Raman and it significantly hampers the SOP spectra even with the 785 nm laser. On the one hand the big spot size of DRIFTS (10 mm) limits the technique to rather large sampling areas, whereas the use of a 50× objective for in-situ Raman measurements permits a focus on small spots and aggregated SOP flakes. Moreover, “environmental” factors like temperature changes, artificial light, limited space and vibrations when people pass by need to be considered for in-situ measurements in museums.
Finally, the results show the experimental use of SOP in modern reverse glass paintings. Among several rare SOP (e.g. PB52, PR81), two of them (PG1, PV2) have never been reported before in any artwork.
This work addresses the identification of synthetic organic pigments (SOP) in eight modern reverse paintings on glass (1913–1946) by means of an in-situ multi-analytical approach. We combined the complementary properties of mobile Raman spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to overcome the main disadvantages of each method: extensive band overlapping in DRIFT spectra and fluorescence problems in Raman spectra. A collection of DRIFTS reference spectra enables a precise pigment identification by DRIFTS and establishes this method as a serious non-destructive alternative for the identification of SOP. The group of β-naphthol pigments yielded valuable results for both methods, whereas synthetic alizarin (PR83) was preferentially detected by DRIFTS. Finally, uncommon triaryl carbonium pigments and two azo group-based yellows were identified in the paintings by means of Raman spectroscopy.
A Genetic Toolbox for Exploring the Life Style of the Rock-inhabiting Black Fungus Knufia petricola
(2019)
After their discovery on rock surfaces in cold and hot deserts, a polyphyletic group of ascomycetous black fungi was found to dominate a range of hostile environments – natural and man-made, from salterns to dishwashers, roofs and solar panels. Together with bacteria and algae they may establish sub-aerial biofilms and cause weathering of the surfaces they grow on. Their impressive survival abilities as well as their constitutive protective pigmentation and cluster-like microcolony organisation are similar in environmental isolates as well as in heat-tolerant opportunistic pathogens of animals and humans. The exact genetic properties that ensure their survival in extreme environments can be studied if some black fungi were amenable to genetic manipulations. We selected the rock-inhabiting fungus Knufia petricola (class Eurotiomycetes, order Chaetothyriales) that grows moderately in axenic culture and exhibits all the characteristics of black yeasts such as yeast-like cell growth, absence of reproductive structures and constitutive dihydroxynaphthalene (DHN) melanogenesis. For this environmental strain we developed protocols to efficiently generate and transform protoplasts resulting in stable homokaryotic transformants by targeting genes involved in pigment synthesis and expressing fluorescent reporter genes. Hence, endogenous and foreign genes can be expressed from episomal AMA1-containing plasmids and genome-integrated DNA constructs. Moderate rates of homologous recombination allow for both ectopic and targeted integrations. CRISPR-Cas9 was further validated as a strategy for obtaining selection marker-free mutants and silencing via RNA interference as an approach to study essential genes. Availability of this genetic toolbox and an annotated genome sequence is paving the way for studying interactions of K. petricola and other black yeasts with environmental stressors, material surfaces, soil matrices and phototrophic symbionts.
Leaching processes are responsible for the release of biocides from treated materials into the environment.
Adequate modeling of emission processes is required in order to predict emission values in the framework of the risk assessment of biocidal products intended for long-term service life. Regression approaches have been applied to data obtained from the long-term monitoring of biocide emissions in experiments involving semi-field conditions. Due to the complex interaction of different underlying mechanisms such as water and biocide diffusion and desorption, however, these attempts have proven to be of limited usefulness e at least, for the available biocide emission data. It seems that the behavior of the biocide emission curve depends to a considerable extent on whichever underlying mechanism is slowest at a given point in time, thus limiting the amount of biocide available for release. Building on results obtained in the past few years, the authors propose a criterion for determining which mechanism controls the leaching process at a given point in time based on the slope of the log-log emission curve. In addition, a first-order approximation of this slope value is presented which displays advantages both in terms of computability and interpretability. Finally, an algorithm for the determination of breakpoints in the slope of the log-log emission curve is presented for the demarcation of phases within which one mechanism acts as a limiting factor.
RNA virus populations are composed of highly diverse individuals that form a cloud of related sequences commonly referred to as a ‘quasispecies’1–3. This diversity arises as a consequence of low-fidelity genome replication4,5. By contrast, DNA Virus populations contain more uniform individuals with similar fitness6.
Genome diversity is often correlated with increased Fitness in RNA viruses, while DNA viruses are thought to require more faithful genome replication. During DNA replication, erroneously incorporated bases are removed by a 3′-5′ exonuclease, a highly conserved enzymatic function of replicative DNA but not RNA polymerases. This proofreading process enhances replication fidelity and ensures the genome integrity of DNA organisms, including large DNA viruses7. Here, we show that a herpesvirus can tolerate impaired exonucleolytic proofreading, resulting in DNA virus populations, which, as in RNA viruses8, are composed of highly diverse genotypes of variable individual fitness. This indicates that herpesvirus mutant diversity may compensate for individual Fitness loss. Notably, in vivo infection with diverse virus populations results in a marked increase in virulence compared to genetically homogenous parental virus. While we cannot exclude that the increase in virulence is caused by selection of and/or interactions between individual genotypes, our findings are consistent with quasispecies dynamics. Our results contrast with traditional views of DNA virus replication and evolution, and indicate that a substantial increase in population diversity can lead to higher virulence.