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The aim of the lecture is to present the productive interplay of connoisseurs and material analysis using the example of selected drawings from the Rembrandt collection of the Klassik Stiftung Weimar. We try to determine the point at which the question of the materiality of the drawings makes sense in the traditional discourse of connoisseurship. On the one hand, this involves the question of authorship – Rembrandt – or not? – and the locating of attributed drawings in the context of the work. On the other hand, it is about making drawing processes visible, characterizing ways of drawing and workshop practices as well as distinguishing different forms of reworking and copying within the Rembrandt workshop. The material analyses culminate in the question of whether Rembrandt’s inks can be distinguished at all.
It becomes apparent that the newly gained knowledge about the materiality of the drawing no longer reveals itself to the “mere” view of the connoisseur. Rather, it is only generated by the digital image. The rhetoric of connoisseurs must therefore be contrasted with the necessity of a hermeneutics of the digital image. The envisaged “material turn” of drawing science is thus simultaneously able to take up the critique of the question of authorship, which has been growing ever more recently, and to transfer it to a more comprehensive perspective of aesthetics of production.
Paper-based SERS test strips
(2016)
For the non-destructive chemical analysis of organic compounds, several different methods such as NMR, UV-vis absorption, IR, Raman, or fluorescence spectroscopy are available. However, all available methods have some restrictions such as the necessity of a large sample amount, interferences in the presence of water, or overlapping signals from the analytes or matrix. Surface enhanced Raman scattering (SERS) allows to observe analytes directly without labelling in low concentrations in aqueous solutions and to identify them by their spectral fingerprint. Therefore, in this work we use SERS as a detection method for different analytes in low concentrations in combination with paper-based test strips as SERS substrates and for sample preparation.
We present a spray method for the preparation of SERS test stripes.[1] With this spray method, nanoparticle solution was deposited on cellulose and glass fibre paper as SERS substrate. The prepared paper-based test strips were tested with classical SERS reporter molecules, e.g. rhodamine 6G, 4-aminothiophenol, and adenine. For the quantification of analytes, highly reproducible signal intensities are necessary, which can be realized with the test strips in acceptable quality. Moreover, employing intensity vs concentration calibration for the analytes, data analysis revealed a behaviour that was best described by a Langmuir isotherm, stressing the strong distance dependence of the SERS effect.
For an easier identification of analytes in a mixture of compounds, the paper-based test strips were functionalised with hydrophobic barriers by wax printing. With these microfluidic paper-based analytical devices (µPAD) the sample mixture can be separated by the chromatographic effects of the paper and the different analytes can be separately detected and identified by SERS.
[1] A. Bolz, U. Panne, K. Rurack, M. Buurman, Glass fibre paper-based test strips for sensitive SERS sensing, Anal. Methods, 2016, 8, 1313-1318.
Surface enhanced Raman scattering (SERS) is a fast and sensitive spectroscopic method for the identification of analytes. With available portable Raman spectrometers, on-site analysis is possible. However, for on-site analysis, SERS substrates, which are cheap, easy to prepare, and simple in sample handling are necessary. Relevant analytes in the addressable concentration region for SERS are e.g. antibiotics and pesticides. Here, we present paper-based test strips for SERS analysis which are coated with silver nanoparticles. The coating was realized with different deposition methods of nanoparticle solutions. The papers were also functionalised with hydrophobic barriers to create μPADs. The strips were tested with selected analytes (e.g., adenine, rhodamine-6G) over a broad concentration range. The focus of our study lay on reproducibility and optimum SERS signal intensity.
For the quantification of analytes, highly reproducible signal intensities are necessary. We have realized this reproducibility in acceptable quality. Moreover, employing intensity vs concentration calibration for the analytes, data analysis revealed a behaviour that was best described by a Langmuir isotherm, stressing the strong distance dependence of the SERS effect. For a fast and reproducible analysis of the data, a Labview program was finally compiled, which was fed with the calibration data and derived the concentration of analyte unknowns accordingly.
The fast identification and quantification of analytes in the field of food safety or environmental analysis is difficult. Surface enhanced Raman scattering (SERS) is an analytical method which can be used simultaneously for the rapid identification and concentration determination of trace analytes,[1,2] usually covering a large dynamic range from nanomolar up to molar concentrations. The identification of the molecules is accomplished through the specific fingerprint of a molecule’s Raman spectrum.
For facile and straightforward SERS measurements, we present here a combination of paper-based SERS test strips with microfluidic systems on paper as a microfluidic paper-based analytical device (μPAD). The SERS μPAD is thus principally suited for cheap, fast, non-destructive, label-free and portable detection of analytes. In this system basically, the use of the microfluidic structured paper increases the sensitivity and suppresses background signals of the SERS assay.
Deposition of the SERS substrate on the test strips is simple and relies on an inkjet printer. For the optimization of the reproducibility and intensity of the SERS signal, we tested different nanoparticles, different numbers of print cycles and different paper types. The nanoparticle solutions used in the μPAD preparation were gold and silver nanoparticle solutions. The paper types were cellulose and glass fiber. SERS arrays were prepared by printing and compared to arrays prepared by spraying. The optimized μPAD was used for the identification and quantification of pure analyte solutions (e.g., adenine) and mixtures of compounds, the concentration series following Langmuir isotherms.
Relevant analytes in the field of food safety are antibiotics and pesticides. We apply the SERS microfluidic paper-based analytical devices for the detection of antibiotics (enoxacin, enrofloxacin) and pesticides.
In this paper, members of three research teams, namely the Turfan Project of the Berlin BrandenburgAcademy of Sciences and Humanities, the Berlin-based research project on pigments in Central Asianpaper manuscripts, and the Hamburg-based project on the history and typology of Central Asian papermanuscripts, present some of the results of their cooperation. The investigated manuscripts belong tothe Berlin Turfan Collection. On the basis of different examples the contribution of scientific methods tophilological scholarship within a multidisciplinary approach is demonstrated.
This article presents the findings resulting from the material analysis of several Sanskrit palm-leaf manuscripts from a corpus partly preserved in Nepal, viz. in the National Archives, Kathmandu (NAK), and in the Kaiser Library (KL), which is likewise situated in Kathmandu. The analysis was undertaken in March 2013. The colleagues of the NAK allocated a room in their precincts to us, where we could set up our mobile laboratory, and gave us access to the required manuscripts from their holdings. The officials of the KL, in turn, allowed us to take some of their valuable and ancient manuscripts to the NAK. In this way, we were enabled to conduct multi-instrumental studies on writing materials of great antiquity and interest.
The Nepal-German Manuscript Preservation Project (NGMPP) microfilmed two sets of the rNying margyud 'bum: in 1989 the set stored in the National Archives in Kathmandu (NAK) and in 1992 another set during an expedition to Nubri, Samagaon. Both microfilming were carried out under the local director of the Nepal Research Centre (NRC) in Kathmandu, and who has also discussed the two (and other) rNying ma rgyud 'bum sets on several occasions.2 The NAK and Nubri rNying ma rgyud 'bum sets were extensively studied and catalogued (Almogi) within the framework of the Tibetology sub-project "The Manuscript Collections of supervision of Franz-Karl Ehrhard, who was at the time the the Ancient Tantras (rNying ma rgyud 'bum): An Examination of Variance," conducted at the Researcher Group "Manuscript Cultures in Asia and Africa," University of Hamburg (2008-2011).
The great variety of manuscripts found in the Turfan oasis at the Start of the twentieth Century by Grünwedel and Le Coq reflects the cultural backgrounds of, and communication among, the people who travelled along the network of Eurasian trade routes. Specifically, this Connection is directly reflected by the use and distribution of inks, pigments, and papers. Research is now underway to examine these and a report on the initial findings is given below.
One of the most important materials presenting and witnessing human culture is paper. The cleaning of paper is often necessary because contamination must be removed so that the fragile organic substrate can be preserved. The conventional cleaning methods are mechanical or involve the application of chemicals. These methods can damage drawings or print layers to some extent or make the original paper substrate brittle. More specifically, the use of a scalpel blade can cause damage to fibers. Chemical cleaning is difficult to perform locally, can dissolve foreign matter that then migrates into the paper substrate, or involves volatile organic compounds that can be harmful to the conservator. There is, therefore, a need for new conservation technologies aimed at the safe cleaning of paper. Lasers have proved to be an appropriate tool for cleaning as the energy dose and penetration depth at the specific point of contamination can be controlled. Additionally, if used properly, laser cleaning is not destructive to the paper.