scholarly journals Forces for Folding

Acta Naturae ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 126-128
Author(s):  
Colyn Crane-Robinson
Keyword(s):  
Nucleic Acids ◽  
Experimental Determination ◽  
Thermodynamic Data ◽  
Structural Information ◽  
Fundamental Question

Understanding the nature of the forces driving the folding of proteins, nucleic acids and the formation of their complexes absolutely requires thermodynamic data, in addition to structural information. In practical terms, this means the use of super-sensitive scanning and titration calorimeters for experimental determination of the heats (enthalpies) characterising these processes. Peter Privalov was both an experimental thermodynamicist and a calorimeter designer/manufacturer who followed and propagated this credo. The sum total of his many publications, every one of which addresses a fundamental question, is his lasting epitaph.

The pressure dependence of the dehydration of gypsum to bassanite

1987 ◽  
Vol 51 (361) ◽  
pp. 453-457 ◽  
Author(s):  
J. D. C. McConnell ◽  
D. M. Astill ◽  
P. L. Hall
Keyword(s):  
Elevated Temperature ◽  
Experimental Determination ◽  
Volume Change ◽  
Pressure Dependence ◽  
Thermodynamic Data ◽  
Dehydration Reaction ◽  
Temperature And Pressure ◽  
The Stability ◽  
Very High

AbstractA new experimental determination of the stability relationships for the dehydration of gypsum to the hemihydrate mineral bassanite at elevated temperature and pressure is described. The experimental method used depends on the observation of very small changes in pressure on the onset of reaction due to the potential volume change in the reaction. The technique yields P-T data of very high precision for this dehydration reaction, and the method is likely to be of use for other reactions. The experimental P-T results have been compared with those calculated from existing thermodynamic data for this reaction.

scholarly journals Impact of increased temperatures on the geochemical behaviour of trivalent actinides in aquatic systems

2021 ◽  
Vol 1 ◽  
pp. 159-160
Author(s):  
Andrej Skerencak-Frech ◽  
Petra Panak ◽  
Kathy Dardenne ◽  
Jörg Rothe ◽  
Xavier Gaona ◽  
...  
Keyword(s):  
High Temperature ◽  
Experimental Determination ◽  
Stability Constants ◽  
Host Rock ◽  
Thermodynamic Data ◽  
Near Field ◽  
Extrapolation Methods ◽  
Trivalent Actinides ◽  
Geochemical Behaviour

Abstract. The Safety Case for a radioactive waste repository in deep geological formations requires detailed chemical and thermodynamic information on the stored radionuclides in their relevant oxidation states. Although a comprehensive summary of critically evaluated thermodynamic data is available via the blue book series of the NEA-TDB (“Nuclear Energy Agency – Thermochemical Database”), the majority of this data is limited to ambient conditions (Grenthe et al., 2020). In the case of the disposal of high-active, heat-producing waste, however, the near-field of the repository will experience increased temperatures at early operative phases for several hundred or a few thousand years. Radionuclides may come into contact with aquatic solutions or brines at elevated temperatures in the case of early canister failure. Besides other factors of the overall disposal concept (e.g. the geometry of the repository, type and amount of stored radionuclide inventories), host rock characteristics themselves limit the extent of the allowable temperature increase. For example, in clay formations the maximum temperature should stay at around or below ∼100∘C in order to avoid an irreversible change in the host rock retention capacity, whereas rock salt allows much higher temperatures of up to 200 ∘C. Increased temperatures will have a distinct impact on the geochemical behaviour of radionuclides, potentially affecting their mobility and retention in the near field. Besides reactions at the solid–liquid interface (e.g. dissolution/precipitation reactions of the waste matrix, sorption reactions of the radionuclides to surfaces), complexation reactions with inorganic and organic ligands present in the aqueous phase potentially affect migration behaviour of the radionuclides. A quantitative thermodynamic description of these processes requires standard stability constants (log⁡βn0(T)), as well as standard reaction enthalpies and entropies (ΔrHm,n0, ΔrSm,n0). The precise experimental determination of these data for all relevant radionuclide/ligand reactions requires a vast amount of time and effort. In this regard, reliable extrapolation methods in particular for standard stability constants valid for 25 ∘C to higher temperatures are considered to support a comprehensive description. Recently, the German Federal Ministry of Education and Research (BMBF)-funded collaborative research project “Therm AC” focused on the experimental determination of new thermodynamic data at higher temperatures, as well as the comparison with the analogous results yielded by extrapolation methods. The Thermochemical Database Project of the OECD-NEA (NEA-TDB) is currently in the process of preparing a comprehensive state-of-the-art report on the high temperature thermodynamics of radionuclides, further emphasizing the particular relevance of this interesting topic. Within this contribution, a critical overview on the recent advances in the field of high temperature studies of radionuclides in aqueous solutions will be given. Besides summarizing information on key technical aspects relevant for high temperature studies, the effect of increased temperatures on the complexation of trivalent actinides with chloride will be discussed in more detail in order to illustrate newly derived in-depth understanding of the impact of increased temperatures on the (geo)chemical behaviour of trivalent actinides on the molecular scale (Skerencak-Frech et al., 2014).

Experimental determination of a state equation for dissipative granular gases

1999 ◽  
Vol 96 (6) ◽  
pp. 1111-1116 ◽  
Author(s):  
E. Falcon ◽  
S. Fauve ◽  
C. Laroche
Keyword(s):  
Experimental Determination ◽  
State Equation ◽  
Granular Gases
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