The height of Denier Tournois minting in Greece (1289–1313) according to new archaeometric data

The years 1289–1313 witnessed particularly prolific minting activities at different southern and central Greek mints on behalf of different polities. The coin issues are of great economic and political relevance, and therefore of interest to modern historians. Our understanding of these is based on traditional sources, either numismatic (types and finds), or historical. This paper aims to investigate the possibilities of adding further details to the picture through archaeometry. Specifically, tournois pennies of the three main mints of the region (Clarentza, Thebes, Naupaktos) excavated at Ancient Corinth were analysed according to two different non-destructive methods, X-ray fluorescence spectrometry (XRF) and laser-induced breakdown spectroscopy (LIBS). The resulting relative silver percentages and the fingerprints of the trace elements have supported our attempts to put the different coin types in chronological order and to add detail to the context and intent for each one of these. A vivid picture of monetary production emerges. The different issuing authorities were usually intent on maintaining a decent standard while variously trying to put pressure on rivals or to harmonise their productions with their allies. All the analysed mints were commercial in character, though they were subject to the great political changes affecting Greece in this period, the ambitions of the Angevin dynasty, the various challenges which it faced in Athens, the Peloponnese and the western Mainland, and finally the destructive arrival of the Catalans. In times of need, specifically military, these same mints could therefore rely on further bullion which reached them through internal or external political channels

New Instruments for Nuclear Astrophysics

A major task in experimental nuclear astrophysics is the measurement of cross sections of capture reactions. In the last years, the astrophysics group of NCSR "Demokritos" developed and used a method for conducting this kind of research using a 4π NaI γ-detector. Of great importance in this method is the determination of the efficiency of the detector, which depends on the average multiplicity of the γ-cascade de-exciting the entry state of the produced nucleus. Two new experimental setups have been studied and are in course of installation at the Tandem Laboratory of the Institute of Nuclear and Particle Physics of NCSR "Demokritos", that will provide the possibility for conducting this kind of experiments inhouse. The first one is a new 14x14 inches NaI detector and the second is the BGO Ball of the GASP setup. These detector setups as well as their potential experimental use will be described in detail

X-ray fluorescence analytical criteria to assess the fineness of ancient silver coins: Application on Ptolemaic coinage

The application of X-ray Fluorescence (XRF) analysis in a non-invasive manner on ancient silver coins may not provide reliable bulk compositional data due to possible presence of a surface, silver enriched layer. The present work proposes a set of three complementary analytical methodologies to assess and improve the reliability of XRF data in such cases: a) comparison of XRF data on original and cleaned micro-spots on coin surface, b) Ag K/L ratio test and c) comparison of experimental and theoretically simulated intensities of the Rayleigh characteristic radiation emitted from the anode. The proposed methodology was applied on 82 silver coins from the collection of Ioannes Demetriou, donated to the Numismatic Museum of Athens in the 1890s. The coins originate from different mints and are attributed to the first five Ptolemaic kings' reign (321-180 B.C.). They were analyzed in-situ by using a milli-probe XRF spectrometer. The presence of an Ag-enriched layer was excluded for the majority of them. The silver fineness was found to be high, with very low concentrations of copper and lead. The composition data provide important information about possible sources of silver during the Ptolemaic period and indications of a gradual coinage debasement after 270 B.C. due to economic or technical reasons. © 2011 Elsevier B.V. All rights reserved.Peer Reviewe

Geochemistry of coastal sands of Eastern Mediterranean: The case of Nisyros volcanic materials

Coastal sand samples collected from the northern part of Nisyros volcanic island (Dodecanese, Greece) were investigated for first time for their potential in strategic metals and compared with parental rocks of the island which are Quaternary volcanics with alternating lava flows, pyroclastic layers and lava domes and relevant materials located near granitoids of Northern Greece. The PXRD and SEM-EDS study of the sands revealed enhanced content of feldspars, Fe-Mn oxides, magnetite, tourmaline, pyroxenes, ilmenites, along with zircons, apatite and sulfide inclusions. The fresh hydrothermally deposited clayely material collected from the Nisyros caldera crater had a rather different mineralogical composition from the coastal one (alunite, anhydrite, opal-CT, quartz, kaolinite). UCC-normalized spidergrams indicated that the weathering processes contributed to accumulation of heavy minerals (mainly ilmenite), and strategic metals including V (1920 mg/kg) and Nb (245 mg/kg), in the coastal sand. The low REE concentration (ΣREE + Y = 240 mg/kg) could be attributed to the absence of REE-rich minerals. Moreover, the sands exhibit different geochemical patterns compared to the volcanic source rocks of the island, which are especially enriched in Large-Ion Lithophile Elements (LILE) and depleted in High Field Strength Elements (HFSE), such as Nb and Ta. On the other hand, the caldera material is enriched in volatile components, sulfur, chalcophile elements (Se, Bi, Hg, As, Pb) and Ba. Micro-XRF analyses of representative crystals showed that the high Nb content of the sands was associated with the Ti/Fe-rich phases (e.g. ilmenites). The geochemical composition of N Greece sands showed, because of their origin, enrichment not only in HFSE but also in REE. The study of the coastal heavy mineral sands originating from different geological environments of Greece provides information about the association of their mineral components with REE, other elements of economic interest (e.g. Co, Nb, Ta) and natural actinides. In addition, the study of the black sands of Nisyros island could be considered as a characteristic example of those from other parts of Hellenic Volcanic Arc (HVA) and other relevant Mediterranean regions. © 2017 Elsevier Gmb

New insights into mineralogy and geochemistry of allanite-bearing Mediterranean coastal sands from Northern Greece

Allanite-bearing black coastal sands of Kavala (N. Greece) were studied using a combination of single-crystal XRD, EMPA, μ-XRF, bulk ICP-MS, LA-ICP-MS, μ-XANES and γ-ray spectrometry. The sands are rich in REE (ΣREE + Y: 4010 to 10,810 mg/kg), Th (236–1205 mg/kg) and other critical metals such as Nb, Ta and Co. The main REE- and Th-hosts are allanite and titanite. The allanite unit cell parameters were calculated whereas its formula was found to be (REE0.470Ca1.499Th0.031) (Ti0.031Fe+3 1.089Al1.880) (Si2.906Al0.094O12) (OH). The μ-XANES spectra showed that LREE are present in trivalent oxidation state. Analyses of the non-magnetic sand fractions showed higher LREE (12,470 mg/kg) due to accumulation of allanite. The materials showed elevated radioactivity ranging from 885 ± 13 to 3467 ± 20 Bq/kg. The obtained results provide new insights on the provenance of the sands, the abundance of REE, Th, and other immobile elements, and offer new clues for potential exploration and exploitation. © 2019 Elsevier Gmb

Experimental investigation of metallic thin film modification of nickel substrates for chemical vapor deposition growth of single layer graphene at low temperature

Lowering the growth temperature of single layer graphene by chemical vapor deposition (CVD) is important for its real-life application and mass production. Doing this without compromising quality requires advances in catalytic substrates. It is shown in this work that deposition of Zn and Bi metals modify the surface of nickel suppressing the uncontrollable growth of multiple layers of graphene. As a result, single layer graphene is obtained by CVD at 600 °C with minimum amount of defects, showing substantial improvement over bare Ni. In contrast, Cu, and Mo suppress graphene growth. We also show that graphene grown with our method has a defect density that is strongly dependent on the roughness of the original nickel foil. Good quality or highly defective holey single layer graphene can be grown at will by selecting a smooth or rough foil substrate respectively. © 2016 Elsevier B.V. All rights reserved