An archaeological and chemical investigation of 11th–12th centuries AD glasses from Zeyrek Camii (the Pantokrator church) in Byzantine Constantinople

Fifteen glass window, vessel and glass chunk samples collected from the western part and substructure of Zeyrek Camii (the Pantokrator Church) in Istanbul were analysed using an electron microprobe (EPMA). The results show that these samples are all soda-lime-silica glass. Based on the major and minor elements, two different compositional groups were identified and evidence of recycling/mixing was also revealed. Group 1 is plant ash-based glass, while group 2 is the result of mixing natron and plant ash glasses. Comparison with contemporary glass objects from the eastern Mediterranean shows that these glasses probably derived from at least two different production zones in the Syro-Palestinian region: (1) possibly Damascus or Banias and (2) possibly Tyre. The authors suggest that the trading of plant ash glasses between the Byzantine Empire and the Middle East in the 11th–12th centuries AD was well established based on the archaeological and scientific evidence

Influence of Zeolite Surface in the Sorption of Methane from Molecular Dynamics

We report results of molecular dynamics simulations on the transient and equilibrium surface adsorption of methane in a model Si-LTA zeolite structure with explicit silanol terminal groups. Using probability occupancy maps, 2D occupational densities, and free energy pro¿les, we extract a microscopic picture of the adsorption process, showing surface preferential zones of interaction around the partially exposed oxygen atoms of the surface silanol groups due to attractive silanol guest attractions. The global e¿ect of the loading on the uptake process is observed as a decrease in the free energy barrier as the loading increases and an increase in the surface permeability, calculated either from the initial uptake transient process or from equilibrated trajectories. The order of magnitude of the obtained surface permeability suggests a barrier that becomes relevant to the overall mass transfer for crystal sizes in the range of a few unit cells. Our results support experimental evidence that ascribe surface resistances to severe crystal structure deviations, causing an almost complete blockage of the surface available entering windows.Funding through Ministerio de Ciencia e Innovacion (project MAT2007-64682) and computing time from Red Espanola de Supercomputacion are gratefully acknowledged. A.F.C. acknowledges a research fellowship provided by the Instituto de Tecnologia Quimica UPV-CSIC. We thank an anonymous reviewer for very insightful comments.Combariza Montañez, AF.; Sastre Navarro, GI. (2011). Influence of Zeolite Surface in the Sorption of Methane from Molecular Dynamics. JOURNAL OF PHYSICAL CHEMISTRY C. 115:13751-13758. https://doi.org/10.1021/jp202043tS137511375811