4 research outputs found
Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling
A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems
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First Documented Camelus knoblochi Nehring (1901) and Fossil Camelus ferus Przewalski (1878) From Late Pleistocene Archaeological Contexts in Mongolia
Throughout the arid lands of Africa and Eurasia, camelids facilitated the expansion of human populations into areas that would not likely have been habitable without the transportation abilities of this animal along with the organic resources it provides, including dung, meat, milk, leather, wool, and bones. The two-humped, Bactrian, species of Camelus, C. ferus in its wild state and C. bactrianus when domesticated, is much more poorly known in prehistoric archaeological contexts than its single-humped congeneric, C. dromedarius. Our research uses a convergence of evidence approach to analyze reports and remains of Plio-Pleistocene camelids in Central and Northern Asia and trace the latest-known fossil Bactrian relative, Camelus knoblochi, that seems to have survived in the Gobi Desert until the Last Glacial Maximum (ca. 26.5–19 ka). Rock art depictions, some of which may be of Pleistocene age, record the complexity of nascent human-camel interactions and provide the impetus for further archaeological studies of both the origins of C. bactrianus and its increasingly complex relationships with the highly mobile prehistoric peoples of Central and Northern Asia. Copyright © 2022 Klementiev, Khatsenovich, Tserendagva, Rybin, Bazargur, Marchenko, Gunchinsuren, Derevianko and Olsen.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]