ABSTRACT
The authors discuss functional characterization of Mousterian tools on the basis of their use-wear and residue analysis of five lithic tools from Mezmaiskaya cave and Saradj-Chuko grotto in the North Caucasus. The results represent the first comprehensive use-wear and residue analysis carried out on Mousterian stone artefacts in the Caucasus. This study unequivocally confirms the use of bitumen for hafting stone tools in two different Middle Paleolithic cultural contexts defined in the Caucasus, Eastern Micoquian and Zagros Mousterian.
Subject(s)
Caves , Technology , Artifacts , Archaeology , FossilsABSTRACT
Hydrogen adsorption ability is a key parameter characterizing advanced porous materials. Herein, the influence of platinum catalyst on the interaction of Cu-BTC with hydrogen is thoroughly investigated using volumetric measurements, calorimetric titration, XRD, and IR- and EPR spectroscopy. The first hydrogen adsorption by the Cu-BTC + Pt/C composite leads to an irreversible chemical reaction related to the formation of structural defects during synthesis. This process results in a partial reduction of Cu2+ to Cu0 and is accompanied by a decrease in the specific surface area and the appearance of additional mesopores. The following hydrogen adsorption-desorption cycles are completely reversible and reproducible. Besides, the Pt-containing material maintains a positive trend in excess adsorption up to ultra-high pressures in contrast with pristine Cu-BTC. Above 300-400 bars, it demonstrates a significant superiority in hydrogen capacity over the catalyst-free MOF. The possible nature of such a peculiar phenomenon is suggested.
