[en] Two types of the stability diagram are generally constructed to represent the speciation of the species in a multicomponent system. One plots the domains of predominance that has been discussed in Part 1 of this series. The other plots the distribution of the mass involved called distribution diagrams. Basically, distribution diagrams can be constructed according to the equations of equilibria and mass balances. Because there is only one independent variable, the diagram can be plotted as a function of one particular parameter such as potential, pH, or concentration of the main component or ligand component. Equations can be solved numerically by Newton-Raphson iteration. Some important considerations that are not found in other literature are presented. The method and considerations discussed are not limited to a microcomputer, they can be applied to a mainframe computer as well. Uranium in seven ligand components are used for demonstration

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[en] Different fundamental research papers on uranium IV are presented, some were never edited. Molecular spectroscopy was used for identification and structural study of uranium IV in aqueous or organic solutions. The fields studied are: coordination, stereochemistry, electronic structure and chemical properties. For interpretation of results some studies were made with solid compounds or with thorium compounds or thorium complexes. Knowledge of actinides chemistry is improved, uranium and thorium being models for 5 f ions, extractive chemistry is better understood and new applications are possible

[en] The description of uranium and its compounds, for which the Gmelin Institute has started a series of volumes supplementing the main volume of 1936, follows closely in its arrangements the order chosen for the transuranium volumes. Part A treats ''The Element'', Part B ''The Metal and its Alloys'', Part C ''The Compounds'', Part D ''The Chemistry in Solution'', and finally Part E ''The Coordination Compounds''. Part E comprises two volumes which already have been finished and are available - written completely in English

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[en] Experimental studies have been carried out to analyse the influence of the rate of heat extraction, mold preheat temperature and superheat temperature during pouring, on the type and intensity of macrosegregations in Al-U alloys. Solidification structures in hypereutetic Al-U alloys are presented and the influence of the above mentioned factors qualitatively analyzed. (Author)

[en] A DFT study of U(VI) hydroxy complexes was performed with special attention paid to the [(UO_2)_3(OH)_5(H_2O)_4_-_7]"+ and [(UO_2)_4(OH)_7(H_2O)_5_-_8]"+ species. It was established that the ionicity of the U=O bond increased when moving from [(UO_2)(H_2O)_5]"2"+, [(UO_2)_2(OH)(H_2O)_8]"3"+, [(UO_2)_2(OH)_2(H_2O)_6]"2"+, [(UO_2)_3(OH)_5(H_2O)_4_-_6]"+ to [(UO_2)_4(OH)_7(H_2O)_5_-_8]"+ species. In both [(UO_2)_3(OH)_5(H_2O)_4_-_6]"+ and [(UO_2)_4(OH)_7(H_2O)_5_-_8]"+ complexes, the U=O bond was observed to have a range of different lengths which depended on the composition of the first coordination sphere of UO_2"2"+. The cyclic structures of trimeric complexes were somewhat more stable than their linear structures, which was probably due to the steric effect. (author)

[en] A laboratory serving a national or international safeguards programme receives product samples or scrap materials of uranium or plutonium of a broad spectrum of matrices for analysis. These materials may have been treated over a wide temperature range rendering them, to varying degrees, refractory. The requirement, therefore, is to be able to measure accurately the uranium or plutonium content in these widely varying material types. The New Brunswick Laboratory (NBL) whose mission is to provide analytical chemistry support for the USA Safeguards programme, has enjoyed considerable success in preparing and analysing a broad spectrum of material types. Results of comparisons of chemical measurements on similar materials prepared by various treatments are discussed. The Safeguards Laboratory either needs a measurement method which is insensitive to other elements or needs to use a simple, selective separation of the desired element. The method of Davies and Gray is highly specific for uranium. Modifications to this method developed by NBL permit unbiased measurements with a routine precision of better than 0.1% (RSD) on samples containing at least 50 mg uranium. The effect of impurity elements on the accuracy and precision of this method has been extensively investigated. A tributyl phosphate (TBP) extraction is compatible with the BNL titrimetric measurement for uranium and provides acceptable removal of all elemental interferents except gold, iodine and technetium. Safeguards analysis of plutonium-containing materials encompasses similar diversity of sample matrices. Investigation of the mechanization of the separation and measurement of plutonium is described. (author)

[en] The application of band theory to actinide systems is examined. The fundamental aspects are considered to define the limits of applicability. We then consider the more practical approximate applications to demonstrate their underlying assumptions and range of applicability. Examples are drawn primarily from our own work on Th, α-U and UGe₃