Handheld XRF analysis of gold armlets with crescent-shaped terminals from the prehistoric collection of the Hungarian National Museum

A tanulmányban a Magyar Nemzeti Múzeum Őskori Gyűjteményében található, holdsarlós végű arany karpántok kézi XRF elemösszetételi vizsgálatának eredményeit mutatjuk be. Munkánkban az új, tápióbicskei darab mellett vizsgáltuk a dunavecsei, a magyarbényei, az erdélyi (Kárász Géza gyűjtemény) és a Körös vidéki darabot is. A kézi XRF elemzés alapján megállapíthatjuk, hogy a karpántok jelentős része magas Ag (21–24 wt%) és alacsony Cu tartalommal (0,06–0,17 wt%) rendelkezik. E tárgyak típusuktól vagy lehetséges időrendi besorolásuktól függetlenül viszonylag egységes csoportot (Hartmann A3) alkotnak elemösszetételük alapján. Alacsonyabb Ag tartalommal a Körös vidéki darab (kb. 5,8 wt%) (Hartmann B) és a magyarbényei karpánt szegecsei (kb. 12,3 wt%) bírtak (Hartmann L/Q2). Eredményeink alapján a vizsgált karpántok alapanyaga a korábban, részben más módszerekkel (OES, SR XRF) vizsgált példányokhoz képest (Bellye, Pipe, Mihályfalva) alacsonyabb Ag tartalommal bír. Jelen módszer az elemzett tárgyak nyersanyaga eredetének meghatározására nem alkalmas, mindössze a nyersanyag típusát különíthetjük el, amely termésarany lehetett

Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria

Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction, and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell. It is shown that the Hg(II) uptake mechanism (1) has two kinetically distinguishable components, (2) includes co-opted influx through heavy metal transporters since the slow component is inhibited by Ca2+ channel blockers, (3) shows complex pH dependence demonstrating the competition of ligand binding of Hg(II) ions with H+ ions (low pH) and high tendency of complex formation of Hg(II) with hydroxyl ions (high pH), and (4) is not a passive but an energy-dependent process as evidenced by light activation and inhibition by protonophore. Photosynthetic bacteria can accumulate Hg(II) in amounts much (about 105) greater than their own masses by well-defined strong and weak binding sites with equilibrium binding constants in the range of 1 (muM)-1 and 1 (mM)-1, respectively. The strong binding sites are attributed to sulfhydryl groups as the uptake is blocked by use of sulfhydryl modifying agents and their number is much (two orders of magnitude) smaller than the number of weak binding sites. Biofilms developed by some bacteria (e.g., Rvx. gelatinosus) increase the mercury binding capacity further by a factor of about five. Photosynthetic bacteria in the light act as a sponge of Hg(II) and can be potentially used for biomonitoring and bioremediation of mercury-contaminated aqueous cultures

Disruption Management of Rolling Stock in Passenger Railway Transportation

This paper deals with real-time disruption management of rolling stock in passenger railway transportation. We present a generic framework for modeling disruptions in railway rolling stock schedules. The framework is presented as an online combinatorial decision problem where the uncertainty of a disruption is modeled by a sequence of information updates. To decompose the problem we propose a rolling horizon approach where only rolling stock decisions within a certain time horizon from the time of rescheduling are taken into account. The schedules are then revised as the situation progresses and more accurate information becomes available. We extend an existing model for rolling stock scheduling to the specific requirements of the real-time case and apply it in the rolling horizon framework. We perform computational tests on instances constructed from real life cases and explore the consequences of different settings of the approach for the trade-off between solution quality and computation time

The bottom of the looted cauldron. Part I.

The following study deals with a looted metal sheet artefact probably originating from the Balkan region. Our main goal is to give a preliminary technological characterization of the object by the aid of four different analytical methods (macro- and microscopic observations, Neutron and X-ray Radiography, X-ray Fluorescence Spectroscopy). Using these different techniques together allowed us to characterize this complex metal sheet object more precisely than it would have been possible by traditional archaeological methods. According to our results, it seems that the technological characters of the artefact (e.g. the manufacturing technology, decorations, repair marks) are very similar to the metal sheet cauldrons of the Late Bronze Age and Early Iron Age