Analytische Chemie
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Eingeladener Vortrag
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We have obtained a minute amount of dry ink scratched from the bronze inkwell MS 1655/2. The powder was stored between two glass slides to minimize contamination. For micro analysis by FTIR a sample of the ink powder was transferred into a diamond cell while for confocal Raman spectroscopy a micro sample was placed onto sticky tape. The same portion of the sample was also investigated by scanning electron microscopy, where the elements distribution was determined by EDX.
The aim of our work was to check whether the assumption that the jar was discovered in Qumran can be substantiated. In order to establish the archaeological provenance of the jar we conducted a series of analytical tests on samples of material collected from the jar in April and June 2009. The samples were either found loose within the jar, these being probably constituted by remnants of its original contents, or were clay detached from the inner and outer surface of the jar. In addition, a portion of sand deposit coating the inside of the jar handles was analysed.
Lead (Pb) isotope amount ratios are commonly used in applications ranging from archaeology and forensic sciences to terrestrial and extra-terrestrial geochemistry. Despite their utility and frequency of use, only three certified isotope amount ratio reference materials are currently available for Pb: NIST SRMs 981, 982 and 983. Because SRM 981 has a natural Pb isotopic composition, it is mainly used for correcting instrumental mass discrimination or fractionation. This means that, at present, there are no other certified isotope reference materials with natural Pb isotopic composition that could be used for validating or verifying an analytical procedure involving the measurement of Pb isotope amount ratios.
To fill this gap, two new reference materials, both certified for their Pb isotopic composition, have been produced together with a complete uncertainty assessment. These new reference materials offer SI traceability and an independent means of validating or verifying analytical procedures used to produce Pb isotope amount ratio measurements.
ERM-EB400 is a bronze material containing a nominal Pb mass fraction of 45 mg/kg. ERM-AE142 is a high purity solution of Pb with a nominal mass fraction of 100 mg/kg. Both materials have been specifically produced to assist analysts in verifying or validating their analytical procedures. Note that while one of these reference materials requires the chemical separation of Pb from its matrix (ERM-EB400), the other does not (ERM-AE142). Details on the certification of these isotope reference materials are provided in this report.
Selective Electron Beam Melting (SEBM) is a promising powder bed Additive Manufacturing (AM) technique for near net-shape manufacturing of high-value titanium components. However, as with every emerging technique, the manufacturing processes can still be greatly improved and optimised. In particular, the links between AM settings and the resulting sample porosity is of great interest, as the fatigue life of SEBM parts is currently dominated by the presence of porosity. In this study, the size, volume fraction, and spatial distribution of the pores in model samples have been characterised in 3D, using X-ray Computed Tomography (CT), and correlated to the SEBM process variables. A strong relationship was found with the different beam strategies used to contour, and infill by hatching, a part section. The majority of pores were found to be small spherical gas pores, concentrated in the infill hatched region. Rarer irregular shaped pores were mostly located in the contour region and have been attributed to a lack of fusion between powder particles.
The lecture will discuss the sensitive issue of authentication of the objects of cultural heritage of immense cultural and monetary value if certified to be genuine. It will be made clear that material analysis alone, especially its non-destructive variety conducted by specialists in a single technique, can not prove that the object is genuine. The best material analysis can do, after all appropriate tests have been conducted, is to announce that nothing has been found that contradicts the assumption of genuineness. Moreover, the results of the natural analysis can never be used as the only justification of the authentication in the cases of composite objects such as manuscripts or epigraphs. A certification always requires the expertise of the specialist in the field (be it a historian, paleographer, epigrapher, etc.), whose judgment can be at the most supported by appropriate material analysis.
The most effective approach for testing suspicious artifacts has been established by the forensic science. Here, not the authentication, but the determination of the forgery stands in the focus of the work. Investigation protocols developed within 150 years and constantly improved include a clear statement of the analysis purpose and the definition of plausibility criteria for the possible outcome. The younger sister of the forensics, archaeometry has to overcome additional obstacles such as the heterogeneity of historic material coupled with the scarcity of suitable reference material. Over the last two decades the popularity of archaeometric studies has increased enormously, with the industry-driven development of so-called non-destructive technologies (NDT) that do not require sampling. Further technological developments led to the appearance of NDT methods with extremely small interaction windows (µm range). Each of these methods has limitations that have to be carefully considered when planning the tests of a heterogeneous and often partially degraded historical material. This approach is inherently multi-instrumental, therefore archaeometric and forensic departments unite a number of specialists who work together defining the tasks and the methods involved for their successful completion.
The experimental knowledge about the inks of antiquity and late antiquity rarely goes beyond their visual description. In rare cases, inks typology has been determined by means of microscopy and reflectography, i.e. using their physical and optical properties, respectively. Soot, plant, and iron gall inks form different typological classes of historical black writing materials. Soot ink is a fine dispersion of carbon pigments in a water-soluble binding agent; plant-based ink consists of tannin solution; iron gall-ink presents a boundary case between soot and plant ink— a water soluble preliminary stage (similar to inks from the second group) oxidizes and evolves into a black, insoluble material (similar to the carbon pigments of the first group) when the writing is exposed to air. Each ink class has distinct properties that would readily permit their easy differentiation, if only these historical inks always belonged to just one of the classes above. In reality, inks may contain additives that obscure a clear picture.
All the black inks of the DSS have been hitherto identified as soot inks. Yet some manuscripts, with 1QapGen ar among them, display ink corrosion that is incompatible with the pure soot ink. This type of corrosion commonly observed in medieval manuscripts written with iron gall inks, results from the catalytic action of metallic component in the ink. Early analysis of this ink conducted by Nir El and Broshi in 1996 found copper in the corrosive inks and attributed its presence to the use of bronze inkwells. Re-investigation of the 1QapGen ar ink suggests, however, that the ink composition, soot + copper, agrees well with the ink recipe recorded in the 1st century CE by Dioscorides. Similar inks have been already attested on contemporary Egyptian papyri. The first part of the paper is dedicated to the new results on the inks and corrosion pattern of the 1QapGen ar.
In the second part of the presentation I will focus on the luxury scrolls, a distinct codicological type introduced by E. Tov. Our studies show that the preparation of the writing materials cannot supplement the list of codicological criteria offered by Tov. Therefore, one can divorce the writing material production from its inscription in contrast with the medieval scriptoria practices that included parchment production and copying of the manuscripts.
Material study of inks
(2016)
Our experimental knowledge about the inks of antiquity and late antiquity rarely goes beyond their visual description. In rare cases, inks typology has been determined by means of microscopy and reflectography, i.e. using their physical and optical properties, respectively. Soot, plant, and iron gall inks form different typological classes of historical black writing materials. Soot ink is a fine dispersion of carbon pigments in a water-soluble binding agent; plant-based ink consists of tannin solution; iron gall-ink presents a boundary case between soot and plant ink— a water soluble preliminary stage (similar to inks from the second group) oxidizes and evolves into a black, insoluble material (similar to the carbon pigments of the first group) when the writing is exposed to air. Each ink class has distinct properties that would readily permit their easy differentiation, if only these historical inks always belonged to just one of the classes above. In reality, inks may contain additives that obscure a clear picture.
Even crude observations suggest that the inks of antiquity differed greatly in their composition. We believe, that reconstructing the ink recipes with the help of advanced non-destructive analytical techniques could serve as a powerful accessory in the studies of ancient papyri.
The proposed paper will present a short survey of the methods of material analysis and the challenges offered by ancient inks. (Two) examples of ink studies from the collections of the Israel Museum in Jerusalem and Egyptian Museum in Berlin will conclude the paper.
The international Qumran project coordinated at the BAM, Berlin, resulted in an integrated methodology for determining the original and acquired properties of the skin-based writing surfaces of the Dead Sea Scrolls. This methodology offers a powerful tool for addressing such questions as the provenance, sorting and comparison of manuscripts. In addition, we have developed specific protocols for on-site studies, which were successfully applied to the fragments from the Schøyen collection in Norway. Our studies show that the Dead Sea Scrolls writing surfaces can be divided roughly into three groups: leather, parchments of a light tint, and those of various shades of brown. The latter ones are invariably tanned, whereas the middle group is characterized by the presence of various inorganic salts. Some of the pale parchments, among them the Temple Scroll (11Q19), are remarkably similar to medieval European parchment. Therefore we have formulated the working theory that in the Judaea of the Hellenistic period two different parchment-making traditions existed side by side: an ‘eastern’ one (represented by the tanned parchments of Qumran, closely resembling Aramaic documents from the fifth century BC, and a ‘western’ one (represented by the untanned/lightly tanned ones similar to early Christian Greek parchments).
This division has found support during our first pilot study of the Geniza fragments, in which Babylonian and Palestinian traditions seem to follow the “eastern” and “western” technologies, respectively.
The evolution and socio-geographic distribution of writing inks in late Antiquity and the early Middle Ages build the second focus of the BAM group. We use X-ray fluorescence analysis (XRF) to determine the chemical composition of the inks and NIR-reflectography for their typology. Here the early appearance of the metal containing inks clearly belongs to the western tradition as opposed to the continuous use of soot inks in the East.
Investigation of manuscripts found in sites along the Silk Road shows the history of communication and exchange between Asia and the Mediterranean over the centuries. Different scripts and languages preserved on paper in certain styles provide information about traditions and provenance.
To get an idea of the cultural background of the highly developed painting techniques obvious in some illuminated manuscripts, the material used for writing and painting is analyzed. Singular Sogdian and Tocharian manuscripts from Turfan show text on one side with a colorful painting on the other side of the document. In comparison with other productions of different periods or usages from the site, special features are worked out to characterize cultural roots or influence in the network of relationships. Details analyzed in the most elaborated documents Show various influences led to the colorful masterpieces.
Similar to the success story of digital photography a major upheaval has been observed in digital industrial radiology. This paper is split into 3 parts:
Part 1: Film Replacement and Backscatter Imaging: Computed radiography with phosphor imaging plates substitutes film applications. Digital Detector Arrays enable an extraordinary increase of contrast sensitivity in comparison to film radiography. The increased sensitivity of digital detectors enables the efficient usage for dimensional measurements and functionality tests substituting manual maintenance. The digital measurement of wall thickness and corrosion status is state of the art in petrochemical industry. Photon counting and energy discriminating detectors are applied up to 300 Kv provide increased thickness dynamic and material discrimination by synchronously acquisition of images of the high and low energy part of the spectrum. X-ray back scatter techniques have been applied in safety and security relevant applications with single sided access of source and detector. First inspections of CFRP in aerospace industry were successfully conducted with newly designed back scatter cameras. Numeric modeling is used to design X-Ray optics and inspection scenarios as well as conducting RT training.
Part 2: Computed tomography (CT)
Part 3: Micro Radiography and Micro CT.
Designing artificial macromolecules with absolute sequence order represents a considerable challenge. Here we report an advanced light-induced avenue to monodisperse sequencedefined functional linear macromolecules up to decamers via a unique photochemical approach. The versatility of the synthetic strategy—combining sequential and modular concepts—enables the synthesis of perfect macromolecules varying in chemical constitution and topology. Specific functions are placed at arbitrary positions along the chain via the successive addition of monomer units and blocks, leading to a library of functional homopolymers, alternating copolymers and block copolymers. The in-depth characterization of each sequence-defined chain confirms the precision nature of the macromolecules. Decoding of the functional information contained in the molecular structure is achieved via tandem mass spectrometry without recourse to their synthetic history, showing that the sequence information can be read.We submit that the presented photochemical strategy is a viable and advanced concept for coding individual monomer units along a macromolecular chain.
A metrological approach to improve accuracy and reliability of ammonia measurements in ambient air
(2016)
The environmental impacts of ammonia (NH3) in ambient air have become more evident in the recent decades, leading to intensifying research in this field. A number of novel analytical techniques and monitoring instruments have been developed, and the quality and availability of reference gas mixtures used for the calibration of measuring instruments has also increased significantly. However, recent inter-comparison measurements show significant discrepancies, indicating that the majority of the newly developed devices and reference materials require further thorough validation. There is a clear need for more intensive metrological research focusing on quality assurance, intercomparability and validations. MetNH3 (Metrology for ammonia in ambient air) is a three-year project within the framework of the European Metrology Research Programme (EMRP), which aims to bring metrological traceability to ambient ammonia measurements in the 0.5–500 nmol mol−1 amount fraction range. This is addressed by working in three areas: (1) improving accuracy and stability of static and dynamic reference gas mixtures, (2) developing an optical transfer standard and (3) establishing the link between high-accuracy metrological standards and field measurements. In this article we describe the concept, aims and first results of the project.
In this study a metal-matrix-composite with aluminum matrix and Al2O3 particles was investigated with x-ray refraction topography and in-situ tensile loading. It could be observed that after reaching a certain load the specific surface increased steadily. However, the classical radiographs taken for comparison show no damage in the sample.
Preparation of graphene oxide by cyanuric chloride as an effective and non-corrosive oxidizing agent
(2016)
In this work, we report a new method for the synthesis of graphene oxide (GO) using cyanuric chloride as a non-corrosive oxidizing agent.
The mild conditions, simple purification, and scalability of this method are significant advantages over common approaches in which harsh oxidizing agents are used. Moreover, a major drawback with the Hummers' method, the production of toxic gases, is not an issue with this process. This method is a safe and large-scale alternative for the production of GO under mild conditions.
Light damage to selected organic materials in display cases: A study of different light sources
(2016)
The protection of works of art and cultural assets against light-induced aging is vital when planning exhibitions. Newly developed lighting systems render the selection of suitable light sources more difficult, not least in the context of energy–economical systems. This study accordingly examines different lighting systems (fluorescent tubes, halogen lamps, low-voltage metal halide lamps, and LED lamps) in terms of the damage potential they hold for the materials concerned. The changes in color were evaluated using the CIEDE2000 color-difference formula. This study focuses on selected organic materials and shows that changes in color already occur after only a brief exposure time. The color changes induced by the fluorescent tubes were consistently more intense than those induced by the other light sources. The results obtained with the remaining lamps show that the color changes depend more on the material under investigation than on the source used. The changes determined after a relatively short exposure period (five months) vividly demonstrate that exposing sensitive materials to light for longer terms (as is the case during a permanent exhibition) is most definitely a non-viable option.
Molecular machines are a key component in the vision of molecular nanotechnology and have the potential to transport molecular species and cargo on surfaces. The motion of such machines should be triggered remotely, ultimately allowing a large number of molecules to be propelled by a single source, with light being an attractive stimulus. Here, we report upon the photoinduced translation of molecular machines across a surface by characterizing single molecules before and after illumination. Illumination of molecules containing a motor unit results in an enhancement in the diffusion of the molecules. The effect vanishes if an incompatible photon energy is used or if the motor unit is removed from the molecule, revealing that the enhanced motion is due to the presence of the wavelength-sensitive motor in each molecule.
We present the results of a machine learning (ML)- inspired data fusion approach, applied to multi-sensory nondestructive testing (NDT) data. Our dataset consists of Impact-Echo (IE), Ultrasonic Pulse Echo (US) and Ground Penetrating Radar (GPR) measurements collected on large-scale concrete specimens with built–in simulated honeycombing defects. In a previous study we were able to improve the detectability of honeycombs by fusing the information from the three different sensors with the density based clustering algorithm DBSCAN. We demonstrated the advantage of data fusion in reducing the false positives up to 10% compared to the best single sensor, thus, improving the detectability of the defects. The main objective of this contribution is to investigate the generality, i.e. whether the conclusions from one specimen can be adapted to the other. The effectiveness of the proposed approach on a separate full-scale concrete specimen was evaluated.
Sealing and strengthening of the subsoil by grout injection is a major issue in the field of geotechnical engineering. One commonly applied method is jet grouting, which allows creating columns of grouted soil by eroding and mixing the in-situ soil with a thin cement suspension. A general difficulty linked with this method is in predicting the resulting column diameter and its material strength. In this paper, we illustrate the application of a newly developed non-destructive quality assurance tool used to determine the diameter of jet grout columns. This approach incorporates standard crosshole and downhole seismic measurements. To demonstrate its effectiveness, we tested the new approach within two-dimensional finite-difference numerical simulations. Additional field tests showed that this tool is also applicable in real site conditions. For this purpose, three jet grout columns were produced with different process parameters in a depth between 3 and 10 m. The evaluated diameters were within 1 and 1.5 m, slightly deviating from the previously predicted range by the jet grouting contractor. Moreover, we were able to detect the base of the columns at a 10-m depth with no significant difficulties. On the other hand, unsaturated, less compacted sands between the groundwater level and surface considerably affected the seismic data, hence complicating the detection of the top of the columns.