4 Material und Umwelt
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- 4 Material und Umwelt (139)
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- 6 Materialchemie (20)
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- 1 Analytische Chemie; Referenzmaterialien (12)
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The Cairo Geniza is an “archive” discovered in the 19th century in Ben Ezra Synagogue in Fustat, a district in Old Cairo (Egypt), located south of the center of modern Cairo. The giant collection of mostly Jewish documents that vary in genres, languages and writing supports contains a large number of early medieval Hebrew manuscripts, mostly in fragmentary form. The larger part of the Cairo Geniza is stored today in the Cambridge University Library (CUL).
The Geniza provides sources for the literary, linguistic, historical studies of the various aspects Jewish life. As the documents attest, at least two Jewish communities co-existed in Fustat up to 11th century: a so-called Babylonian and Palestinian. These communities had different leaders, different traditions and lived independently. The differences seem to manifest themselves also in the paleographical, codicological and some material properties of the manuscripts produced by each community.
The aim of this project is to compare the inks used in the Jewish documents depending on different variables: support (paper, parchment), purpose of the manuscript (legal, private, religious), provenance of the scribe. For the determination of the inks type and composition we had to choose non-invasive, non-destructive and portable techniques to analyse the corpus directly in the CUL.
The analyses were carried out with a mobile energy dispersive micro-X-ray spectrometer ArtTAX® (Bruker GmbH, Berlin, Germany), which consists of an air-cooled, low-power molybdenum tube, polycapillary X-ray optics (measuring spot size 70 µm in diameter), an electrothermally cooled Xflash detector, and a CCD camera for sample positioning (Bronk et al 2001, Hahn et al. 2010). All measurements are executed using a 30 W low-power Mo tube, 50 kV, 600 µA Mo tube, and with an acquisition time of 15 s (live time) to minimize the risk of damage (Fig. 1, 2).
Fig. 1: XRF spectrometer probe above a manuscript fragment
Fig. 2: Typical element profile of a XRF linescan
The Dino Lite digital stereomicroscope (Fig. 3) features built-in LED illumination at 395 nm and 940 nm and a customized external white light source. During use, the microscope is fastened to a small tripod or mounted on a Plexiglas ring holder that incorporates a white light source.
Fig. 3: Dino Lite digital stereomicroscope
Fig. 4: Details of one fragment (T-S 16.124) observed with the Dino microscope (x20). On the left, when illuminated with NIR (Near-Infrared, 940 nm) light, the ink fades, indicating iron-gall ink. On the right, the image under NIR light does not change. It is carbon ink.
On example of these studies is the manuscript T-S 16.124 (Cambridge University Library, Fig. 5) whom belongs to the third corpus. It is a deed, written in Hebrew, dated from 1328 (= 1017 CE) and witnessed by a very high number of people (6) comparing to the standard of similar documents (between 2 and 3), from at least two different Jewish communities in Fustat (trans congregational). The verso is written in Arabic (Bareket 1999).
Fig. 5: Manuscript T-S 16.124 (Cambridge University Library)
To compare the inks, we used the fingerprint model. This method relies on the determination of characteristic elemental compositions and represents the amount of a minor constituent relative to the main component, iron in iron gall ink (Malzer et al. 2004, Hahn et al. 2004, Rabin et al 2014). However, a calculation of a fingerprint based on XRF measurements is not possible in the case of carbon ink since carbon, its main component, cannot be detected with this technique.
Fig. 6: Ink fingerprint T-S 16-124 (recto) normalized to iron (Fe)
Conclusion
We show that using reflectography and XRF analysis it is possible to sort the inks according to their type. In the case of the iron-gall inks, use of the ink fingerprint, i.e. amount of the vitriol components normalized to iron we can make direct comparisons of the ink composition.
We would like also to stress that though the methods of material analysis listed above have been successfully employed in the field of cultural heritage and conservation including ancient and medieval manuscripts they have not yet been used to study fragments from the Cairo Genizah. Therefore, we believe that this research project is a pioneering study that will provide new insights into the history of Hebrew writing materials, their production techniques and materials and, thus, contribute new data to the field of Hebrew paleography.
We investigated the selection dynamics between a benzalkonium chloride (BAC)-tolerant Escherichia coli strain (S4) and a sensitive wild type under four conditions: in the absence of antibiotics and in the presence of three different sub-inhibitory concentrations of the antibiotic ciprofloxacin in liquid cultures. The wild type was selected over the BAC-tolerant strain in the absence of antibiotics, while the opposite was observed at all ciprofloxacin concentrations investigated.Furthermore, we assessed the evolvability of resistance of the two strains to inhibitory concentrations of ciprofloxacin by performing a serial dilution evolution experiment with gradually increasing ciprofloxacin concentrations. The wild type had a higher probability to develop resistance to ciprofloxacin than the tolerant strain. By the end of the evolution experiment both strains evolved to grow at the highest ciprofloxacin concentration investigated, which was 2048 ×MIC of the wild type.
Aluminum is an often-used building material in modern architecture. In recent years buildings from the 1950th and 1960th are increasingly subject of conservation works including the aluminum parts. Typical surface damages are signs of corrosion caused by weathering processes or scratches in the anodized layer due to extensive wear. To repair damaged aluminum surfaces, there are usually two options: smaller areas are repaired by using a touch-up pen, for larger damages it is necessary to remove the anodized layer completely. Both possibilities are disadvantageous for the objects; the touch-up pen often does not match the color together with an insufficient corrosion protection, while newly anodized layers often differ in color and gloss from the original surface.
For this reason, a research project was initiated to develop a mobile method to repair anodized aluminum parts. The first step focusses on the mobile anodization process by using the electrolyte with a gel substrate. Different cathodic materials are to be tested together with appropriate cooling material. The anodized area should be isolated to protect undamaged areas. Examinations of the produced layers are conducted by using Keyence microscope, eddy current testing and ESEM analysis. Further steps are to transform the coloring and sealing process for mobile application. Color could be applied by using a brush or by spray while the sealing process could be performed with water vapor. An heatable putty knife could be used, if heating up the area will be necessary. Once the application process is developed, the anodization will be tested on samples with artificial damages, fixed in horizontal and vertical positions. The stability of the anodized surface will be examined by accelerated ageing in a climate chamber and outdoor weathering.
The electrolyte (diluted sulfuric acid) was combined with a gel binder to enable a mobile application. Several thickening agents were tested concerning their conductivity and stability in acid systems. Anodization tests with different cathodic material and shapes were conducted. The temperature during anodization was controlled and adjusted if necessary. The anodized area was restricted by using either a lacquer, an adhesive or a removable silicon barrier. The fist results show the feasibility of the method on enclosed areas. The achieved thickness was measured by eddy current testing and the structure was controlled by ESEM analysis. The examinations show a connection between thickness and porosity of the anodized layers and the temperature during the application process.
Next steps are testing mobile coloring and sealing methods followed by mobile anodization on artificial damaged areas.
Since nowadays people spend most of their time indoors, a healthy environment is essential. Volatile organic compounds (VOCs) emitted from furniture and building materials are reported to cause health complaints. Therefore, the usage of low emitting materials will improve the indoor air quality. Quantitative VOC emission testing is usually conducted in emission test chambers under specified controlled conditions as described in DIN 16000-9 and DIN EN 16516.
For reasons of quality control/quality assurance (QC/QA) and for a better comparability of test results from different laboratories, suitable emission reference materials (ERM) are needed. Here, it is important to have a homogenous material with known emission rates over a specific time. Different approaches can be found in literature, inter alia polymer films loaded with the target compound to be released again, or a lacquer material to which a VOC mixture is added. After curing of the lacquer, the material can be loaded into a test chamber. Drawback of those approaches are their relatively fast decreasing emission profiles. For QC/QA purposes according to the test standards, VOC sources with constant emission profiles are desirable.
The EU-funded research project MetrIAQ “Metrology for the determination of emissions of dangerous substances from building materials into indoor air” is working on a multi-component ERM with an envisaged instability of ≤ 10 % in the emission rate over at least 14 days.
Within a doctoral thesis porous materials are impregnated with VOCs. Supercritical CO2 is used as solvent. Thus, the impregnated material does not contain any solvent that may show a measurable amount of emission in the emission test chamber. Furthermore, CO2 has the benefits to have a good availability and low costs. For the selection of porous materials several properties like the pore size, the surface, and the interaction with the components in the atmosphere need to be considered. The impregnation method is optimised while the different porous materials are tested. For the selection of porous materials the pores need to be large enough for the VOC molecules, further influence of the pore size is tested.
Nonporous corundum powder was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices.The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). As a proof of concept, IgG was extracted with protein A from crude human plasma. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application.
ICP-ToF (time of flight) MS enables the analysis of the multi-element fingerprint of single cells. The single cell ICP-ToF-MS is used in the presented poster for the analysis of archaea involved in microbiologically influenced corrosion (MIC) of steel. By means of sc-ICP-ToF-MS, the possible uptake of individual elements from the respective steel is investigated - the information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts. The work combines modern methods of analytical sciences with materials.
Deciphering microbiological influenced corrosion processes on steel with single cell-ICP-ToF-MS
(2022)
Microbiologically influenced corrosion (MIC) is a highly unpredictable process dictated by the environment, microorganisms, and the respective electron source. Interaction pathways between cells and the metal surface remain unclear. The development of this novel single cell-inductively coupled plasma-time of flight-mass spectrometry analytical method and a MIC-specific staining procedure facilitate the investigation of steel-MIC interactions. With this it is possible to analyze the multi-elemental fingerprint of individual cells. The detection method revealed elemental selectivity for the corrosive methanogenic archaeal strain Methanobacterium-affiliated IM1. The interface between material and environmental analysis thus receives special attention, e.g., when considering MIC on solid steel. Hence, the possible uptake of individual elements from different steel samples is investigated. Results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to interact with chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials research.
References.
Im Verbundprojekt R-Rhenania wird eine industrielle Demonstrationsanlage am Standort der Monoverbrennungsanlage Altenstadt der Firma Emter errichtet und im Jahr 2024 den Betrieb aufnehmen. Die vorhandene Rostfeuerung-Monoverbrennung wird so umgebaut, dass ein neues thermochemisches Verfahren integriert werden kann, welches hochwirksame und schadstoffarme Dünger produziert (bis zu 17.000 t/a). Die thermochemischen Produkte werden in Gefäß- und Feldversuchen im ökologischen Landbau auf ihre Düngewirkung getestet. Die Umweltverträglichkeit der Demonstrationsanlage wird untersucht, wie auch die Übertragbarkeit des Verfahrens auf weitere Regionen.
Synchrotron XPS in the soft-X-ray regime is suitable for the detection of light elements commonly found in biological samples. Various model systems of biofilms have been developed and characterised at synchrotron- and lab-based facilities. By obtaining the chemical composition at various information depths, the vertical distribution of iodine in an artificial biofilm have been determined.
Per- and polyfluoralkyl surfactants (PFASs) are industrially produced surface chemicals used in daily applications that have gained public and political attention due their unnaturally high appearance in drinking water, nourishments and soils. Their chemical structures exhibit both lipophilic and hydrophilic properties, leading to a highly inert and persistent character. Various PFASs have shown to be bioaccumulative in plants and animals, and some have been characterized as highly toxic when ingested. When exposed to the environment, PFASs slowly get mobilized by natural water resources, leading to contamination of large areas of soil and natural water sources. While PFASs contamination of drinking water has been investigated intensively, perfluoralkyl contamination of soils has been rarely examined as of yet. At the same time, an increasing amount of PFASs contamination sites are being discovered worldwide, calling for a sophisticated strategy towards analytical characterization. Since the number of known PFASs already exceeds 4700, the established sum parameters like extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF) are key elements to fully survey the impact of exposure. Simultaneously, innovative soil remediation strategies are required to contain environmental destruction and to minimize further
spreading of contaminants. Addressing these challenges requires suitable analytical devices that are capable of mobilizing PFASs in the solid as well as in the liquid phase. The use of combustion ion
chromatography (CIC) enables analysis of both immobile and volatile PFASs and allows the detection of both total fluorine (TF) and EOF or AOF of a given soil or aqueous sample. Based on preliminary results, the clean-up of a PFAS contaminated solid matrix is monitored via EOF detection over time.
Additionally, we demonstrate the pH dependency of hydrogen fluoride absorption on active carbon (AC) and found a simple organic additive to be an effective fluoride scavenger. The presented findings can be contributive with regard to future AOF/EOF sum parameter development and application.