Hochaufgelöste Proton magische Winkel kernmagnetische Resonanz von Wasser absorbiert in kohlenstoff- einwandigen Nanoröhrchen- Nanophysik studie

Hochaufgelöste Magisch-Winkel-Rotation Protonen Kernspinresonanz Studie von Wasser absorbiert in einwandigen kohlenstoff-Nanoröhrchen Nano-Physik StudieSummary Single wall carbon nanotubes (SWNTs) have attracted scientific interest because of their fascinating physical and chemical properties and for their application in materials physics and the chemical industry. The main topic of this Nano-Physics study is the investigation of the properties of water in carbon nanotubes, at different temperatures and at different concentrations of water by using the proton Magic Angle Spinning solid state nuclear magnetic resonance technique. Also the influence of metal clusters, which exist near the carbon nanotubes as a result of the synthesis, is investigated. From the Nuclear magnetic Resonance investigations on water in single wall carbon nanotubes (SWCNTs), as described in this thesis, we can draw the following conclusions: • Water is not absorbed inside SWCNTs, synthesized by the HiPCO method with a Fe catalyst, without further purification. The only water that is sorbed by the sample is water adsorbed at the outside of the nanotubes with a chemical shift of 4.6 – 4.8 ppm. • Acid treatment removes the Fe clusters. After this treatment two water signals are detected, at 4.6 – 4.8 ppm and at 1.3 ppm. • Temperature dependent solid state NMR spectra show that the water which is responsible for the 1.3 ppm line freezes at a temperature much lower than the freezing point of bulk water. This water is assigned to water absorbed inside the nanotubes. • The NMR spectra as a function of the amount of water added to the SWCNT sample shows that the first water that is added to the sample, is absorbed in the tubes. In spite of the hydrophobicity of the inside of the carbon nanotubes water is absorbed due to the water surface tension. • The investigated sample contains SWCNTs with diameters ranging from 0.9 to 1.1 nm and different chiralities. Also from theory it is expected that the tubes can be divided in metallic and semi-conducting tubes. Nevertheless the diameter range, the chirality and the conductivity of the tubes seem to have no effect on the chemical shift of absorbed water. • A simple model calculation using the ring current contribution of each benzene ring of the SWCNT to the chemical shift of water located at the centre axis of the tube yields a water chemical shift value very close to the experimental value of 1.3 ppm

Microstructural and Compositional Characterization of Roman Bronze Coins from Khirbat Edh-Dharih in Jordan

This study aimed at investigating the chemical and mineralogical compositions of five Roman coins (four copper-based and one silver-based alloys) corrosion products, and explore the topographic and morphological microscopic features of the patinas formed on the surface of the copper-based coins. For this purpose, an interdisciplinary approach to micro-destructive methods—microscopic (OM and SEM), mineralogical (XRD), elemental (XRF and SEM-EDX), and molecular (ATR-FTIR)—was conducted. The results showed that cuprite is the principle patina initially formed on the surface of the copper-based alloys by the redundant interaction with the surrounding environmental burial conditions, which is most likely an oxygenated and moisturized soil. This interaction was also observed in the formation of a secondary patina composed of malachite and azurite, which lately was invaded by the corrosive cycle process (bronze disease) represented by the formation of nantokite, atacamite and paratacamite that affected the cuprite primary patina of the copper-based coins during burial. The silver-based coin also suffered an aggressive attack by oxygen, sulfur and chloride ions during burial and formed oxide, sulfide, and chloride of silver, in addition to the corrosion products of cuprite, atacamite, and carbonate of copper, which is one of the alloying elements of this coin. The findings of this study also show that the copper-based coins were made of quaternary Cu-Sn-Zn-Pb alloy, and the silver-based coin was made of ternary Ag-Cu-Sn alloy. Therefore, the study points out that these coins were suffering from the corrosion phenomenon by the reaction with oxide, sulfide, carbonate, hydroxyl, and chloride ions, which are most likely found in the burial soil and incorporated within the alloy corrosion products. Contamination with Si, Fe, Al, and Ca elements present in the soil was also seen. We recommend protecting these alloys to prevent further degradation that may occur during storage and exposure to the atmosphere after excavation

Characterizing archaeological bronze corrosion products intersecting electrochemical impedance measurements with voltammetry of immobilized particles

[EN] Application of electrochemical impedance measurements to microparticulate deposits of copper corrosion products attached to graphite electrodes in contact with 0.10 M aqueous HClO4 electrolyte is described. The impedance measurements were sensitive to the applied potential and the amount of solid sample and were modeled taking into account the contribution of the uncovered base electrode. Several pairs of circuit elements provide monotonic variations which are able to characterize different corrosion compounds regardless the amount of microparticulate solid on the electrode. Application to a set of archaeological samples from the archaeological Roman site of Gadara (Jordan, 4th century AD) permitted to establish a grouping of such samples suggesting different provenances/manufacturing techniques.Financial support from the MINECO ProjectsCTQ2014-53736-C3-1-P and CTQ2014-53736-C3-2-P which are also supported with ERDF funds and Grants ES-2012-052716 and EEBB-I-16-11558 is gratefully acknowledgedRedondo-Marugan, J.; Piquero-Cilla, J.; Domenech Carbo, MT.; Ramírez-Barat, B.; Al Sekhaneh, W.; Capelo, S.; Doménech Carbó, A. (2017). Characterizing archaeological bronze corrosion products intersecting electrochemical impedance measurements with voltammetry of immobilized particles. Electrochimica Acta. 246:269-279. https://doi.org/10.1016/j.electacta.2017.05.190S26927924

CHARACTERIZATION AND DATING OF ARCHAEOLOGICAL EXCAVATED HUMAN BONE FROM JORDAN BY HIGH-RESOLUTION 31P AND 14C NMR AND FOURIER TRANSFORMATION INFRARED

Solid-State Nuclear Magnetic Resonance (SS-NMR) and Attenuated Total Reflection Fourier Transformation Infrared (ATR-FTIR) spectroscopy have excellent measurement performance for both organic and inorganic parts of bone or dental dentin. Solid-State Magic-Angle Spinning Nuclear Magnetic Resonance (SS-MAS-NMR) spectroscopy is an effective and constructive method for classifying samples, whether they are new or old. The objectives of this study include finding a new method for dating bone by SS-MAS-NMR and ATR-FTIR studies of old bone, supported by absolute dating of radioactive carbon isotopes. The specific objectives can be addressed by measuring the decomposition factor of the organic fraction in ancient bones and dentin in modern teeth, which are most similar to bones in terms of chemical composition, to arrive at a new time formula for the dating method. Eight old samples and one fresh tooth sample were taken for comparison. The method studied will be established as a new tool for characterizing ancient bone samples and detecting hydroxyl in bone minerals by SS-MAS-NMR

Deterioration and conservation of an archaeological Byzantine lead sarcophagus from Jerash, Jordan

The research looks at a Byzantine sarcophagus made of lead, found in Jerash (Gerasa), Jordan, kept in the warehouse of the Jerash Museum under No.1824. The sarcophagus was exposed to unsuitable storage conditions that caused severe damage. Examination by optical stereomicroscope and scanning electron microscope revealed that the sarcophagus suffered from various deterioration phenomena, for example, the presence of corrosion layers, folds and various cracks. The analysis of the sarcophagus by the EDX unit attached to a scanning electron microscope and x-ray fluorescence, showed that it contained 98% lead, in addition to a very small percentage of other elements such as iron, aluminum, sodium, silicon, and carbon. Analysis by X-ray diffraction revealed that the sarcophagus also contained minerals, which included Graphite (C), Lead (Pb), Litharge (PbO), Cerussite PbCO3, Hydrocerussite 2PbCO3.Pb (OH)2. The treatment, restoration, and maintenance stages of the lead sarcophagus were then carried out and were followed by mechanical and chemical cleaning and straightening of the deformed areas. The missing parts were also integrated, and the four sides of the sarcophagus were assembled using plexiglass as a support material. Treatment with a benzotriazole solution in ethanol with a concentration of 5%, and with Paraloid B72, also with a concentration of 5% were carried out (coating). The sarcophagus cover was also completely repaired. After completion of the treatment, restoration, and conservation processes of the sarcophagus, a transparent glass cabinet of 1 cm thick was designed for its display inside the Jerash Museum in an environment with a relative humidity of 25-30% and temperature of 20-22 °C.La ricerca prende in esame un sarcofago bizantino in piombo, rinvenuto a Jerash (Gerasa), in Giordania, conservato nel magazzino del Museo di Jerash con il n. 1824. Il sarcofago è stato esposto a condizioni di conservazione non idonee che hanno causato gravi danni. L’esame allo stereomicroscopio ottico e al microscopio elettronico a scansione ha rivelato che il sarcofago soffriva di vari fenomeni di deterioramento, ad esempio erano presenti strati di corrosione, pieghe e crepe varie. L’analisi del sarcofago da parte dell’unità EDX collegata a un microscopio elettronico a scansione e fluorescenza a raggi X, ha mostrato che conteneva il 98% di piombo, oltre a una piccolissima percentuale di altri elementi come ferro, alluminio, sodio, silicio e carbonio. L’analisi mediante diffrazione di raggi X ha rivelato che il sarcofago conteneva anche minerali, che includevano grafite (C), piombo (Pb), litargio (PbO), cerussite PbCO3, idrocerussite 2PbCO3.Pb (OH)2. Sono state quindi eseguite le fasi di restauro e manutenzione del sarcofago in piombo, seguite da pulitura meccanica e chimica e raddrizzatura delle zone deformate. Sono state integrate anche le parti mancanti e i quattro lati del sarcofago sono stati assemblati utilizzando il plexiglass come materiale di supporto. Sono stati effettuati trattamenti con una soluzione di benzotriazolo in etanolo alla concentrazione del 5%, e con Paraloid B72, anch’esso alla concentrazione del 5% (coating). Anche la copertura del sarcofago è stata completamente restaurata. Al termine degli interventi di restauro e conservazione del sarcofago, è stata progettata una teca in vetro trasparente dello spessore di 1 cm per la sua esposizione, all’interno del Museo di Jerash, in un ambiente con umidità relativa del 25-30% e temperatura di 20-22 °C