Dissolution of the Soviet Union

The dissolution of the Soviet Union was the process of internal disintegration within the Soviet Union (USSR), which resulted in the end of the existence of the country and of its federal government as a sovereign state, which in turn resulted in its 15 constituent republics gaining full independence on 26 December 1991. It brought an end to General Secretary (also President) Mikhail Gorbachev's effort to reform the Soviet political and economic system in an attempt to stop a period of political stalemate and economic backslide. The Soviet Union had experienced internal stagnation and ethnic separatism. Although highly centralized until its final years, the country was made up of 15 top-level republics that served as homelands for different ethnicities. By late 1991, amid a catastrophic political crisis, with several republics already departing the Union and the waning of centralized power, the leaders of three of its founding members declared that the Soviet Union no longer existed.

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Local, element-specific and time-resolved dissolution processes on a Mg–Y–RE alloy – Influence of inorganic species and buffering systems

Christian Ludwig, Noémie Elise Ott, Andrea Ulrich

The effect of body fluids inorganic species on element-specific dissolution of a Mg-Y-Rare earth elements (RE) alloy was investigated by flow microcapillary plasma mass spectrometry. A new important aspect of this method is the online monitoring of precipitation dynamic in solution. Adding calcium and phosphate to unbuffered NaCl solutions beneficially stabilises the corrosion products formed. But the choice of the buffer is critical for the Mg-Y-RE alloy degradation mechanisms. Tris(hydroxymethyl)aminomethane leads to strong active dissolution because it complexes the ionic species necessary for corrosion product stabilisation whereas a thin partially protective layer can form in borate and carbonate buffered solutions. (c) 2013 Elsevier Ltd. All rights reserved.

2013

Monitoring and understanding Cu catalyst dissolution during CO2 electroreduction

Jan Vávra

Electrochemical reduction of carbon dioxide is a promising approach to decrease the amount of anthropogenic CO2 being released into the atmosphere, provided that a surplus of renewable electrical energy is available. Copper based materials are at the center of attention as a catalyst to this reaction. The exact atomic arrangement of the Cu surface determines the selectivity and activity of the electrochemical reaction. However, recent evidence reports morphology changes of the Cu catalyst surface during the course the reaction. This thesis investigates the operational stability of Cu catalysts with various in-situ techniques, particularly liquid cell TEM, which was adapted to electrochemical CO2 reduction reaction so that it provides morphological and structural information on the catalyst in real-time. Two distinct stages contributing to the reconstruction of Cu catalysts are identified. In the first stage, the catalyst dissolves and spontaneously oxidizes during its contact with the reaction environment. As the reducing potential is applied, the initially dissolved Cu deposits back onto the working electrode. In the second stage, during the catalyst operation at reducing potentials, the dissolution/redeposition continues in the close vicinity of the catalyst surface. Formation of transient [CuCO]+ complexes is identified as the major process responsible for the operational dissolution of Cu catalysts. The provided mechanistic understanding of Cu catalyst (in)stability during electrochemical reduction of CO2 rationalizes the efforts in designing catalysts and electrolyzers with long-term stable operation and motivates further investigation on how to control the operational redeposition of Cu to continuously refresh the active surface motives.

EPFL2022

Effect of different ions on dissolution rates of silica and feldspars at high pH

Mahsa Bagheri, Barbara Lothenbach, Karen Scrivener, Mahdieh Shakoorioskooie

The dissolution kinetics of silica-containing minerals in aggregates influences strongly the process of ASR in concrete. In this paper, the effect of different ions on the dissolution rates of SiO2 (amorphous and quartz) and feldspars at high pH values was studied by following the increase of silicon concentrations in dissolution experiments and with a novel approach of measuring the evolution of scratches of polished surfaces. The second method avoided the problem of precipitation in some systems, such as the formation of C-S-H when calcium was present and lithium silicates in the presence of lithium. At high pH values, lithium, calcium and sulfate increased the dissolution rates of silica and feldspars, while iron, magnesium and additional NaCl, KCl or CsCl showed no significant effect. In contrast, aluminium slowed down significantly the dissolution rates of quartz, amorphous silica and Na and K-feldspar at for all temperatures studies: 20, 40 and 60 degrees C.

PERGAMON-ELSEVIER SCIENCE LTD2022

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Soviet Union

The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominal

Russia

Russia (Rossiya, rɐˈsʲijə), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world by area, its vast landmass stretc

Ukraine

Ukraine (Ukraina, ʊkrɐˈjinɐ) is a country in Eastern Europe. It is the second-largest European country after Russia, which borders it to the east and northeast. It also borders Belarus to the north;