XAFS analyses of molten metal fluorides

X-ray absorption fine structure studies of molten metal fluorides containing the materials related to nuclear engineering are intensively summarized. By using XAFS spectra data of divalent and trivalent cation metal fluorides in molten state which have been collected by authors’ group for a few years, local structure have been extracted and discussed systematically in conjunction with other spectroscopic studies and numerical calculations. In molten divalent fluorides, tetrahedral coordination of fluorides around a cation is predominant. In the case of pure molten trivalent fluorides, structure with more than 6-coordination has been suggested in some cases, but octahedral coordination structure is much stabilized at heavier rare earth metal fluorides. By mixing with alkali metal fluorides, it is a general trend that inter-ionic distances keep constant, but coordination number of fluorides decreases. In experimental chapter, all the details of sample preparation, furnace installation, X-ray optics setups and data analyses procedures are explained. Finally, future expectations of XAFS technique are also suggested

L’ombre portée de la défaite : La Révolution française dans l’historiographie japonaise de l’après-guerre.

Monde moderne de Shibata Michio et Robespierre de Chizuka Tadami ont marqué après la seconde guerre mondiale les générations de chercheurs travaillant sur la Révolution française. Cet article se propose d’examiner ces deux ouvrages dans une perspective comparatiste. Deux points communs s’imposent. Premièrement, ils recherchent tous deux les relations entre trois domaines au cœur des interrogations japonaises depuis la Révolution de Meiji : les questions de la modernité, celles de la place du mouvement populaire dans la construction de la politique, et la naissance puis la construction de l’État. Deuxièmement, ils partagent l’interprétation d’Albert Soboul selon laquelle le « drame de germinal » a causé la rupture de « l’alliance » entre le peuple parisien et le gouvernement révolutionnaire et a conduit au 9 Thermidor. C’est le processus d’évolution de cette alliance que cet article se propose de réexaminer, particulièrement du point de vue de « l’opinion publique […] comme prise en compte et résultat de la parole et des écrits parisiens de l’an II ».After the Second World War, Modern world, by Michio Shibata, and Robespierre, by Chizuka Tadami, have been milestones for the generations of researchers studying the French Revolution. The objective of this article is to examine both works with a comparative perspective. Two similarities quickly become apparent. First, they are both studying the relationship between three issues that were at the core of the Japanese research topics: the issue of modernity, the question about the place of popular movements in the development of politics, and the question about the birth and construction of the State. Second, they both share the same understanding of Albert Soboul, which was that the “Germinal tragedy” was the cause of the dissolution of the “alliance” between the people and the revolutionary government, and that it led to the 9 Thermidor events. This article will be examining the alliance’s evolution process, particularly from the viewpoint of “the public opinion […] as the expression and result of the Parisian speeches and publications of Year II.

Michio Shibata (1926-2011)

Michio Shibata est décédé à Tokyo, le 5 mai 2011, à l’âge de quatre-vingt-quatre ans. Il était l’un des plus anciens membres de la Société des études robespierristes. Né à Kyoto en 1926, Michio Shibata est entré à la section d’histoire de l’Occident de l’Université impériale de Tokyo en avril 1945. Bien qu’appelé au service militaire juste après son entrée à l’université, il a repris ses études à l’issue de la guerre et les a terminées en septembre 1948. Après avoir été professeur de lycée, i..

Reaction dynamics analysis of an E. coli protein translation system by computational modeling

A single enzymatic reaction can often be described by Michaelis-Menten kinetics, but once reactions are connected to one other, it becomes difficult to understand and capture a complete description of the reaction dynamics due to its high dimensionality. To elucidate the dynamic features of a biologically relevant large-scale reaction network, we constructed a computational model of minimal protein synthesis consisting of 241 components and 968 reactions that synthesize the Met-Gly-Gly (MGG) peptide based on an Escherichia coli-based reconstituted in vitro translation (IVT) system [1]. We performed a simulation using parameters collected primarily from the literature and found that the rate of MGG peptide synthesis becomes nearly constant in minutes, thus achieving a steady-state similar to experimental observations. In addition, concentration changes to 70% of the components, including intermediates, reached a plateau in a few minutes. However, the concentration change of each component exhibits several temporal plateaus, or a quasi-stationary state (QSS), before reaching the final plateau. To understand the complex dynamics, we focused on whether the components reached a QSS, mapped the arrangement of components in a QSS in the entire reaction network structure and investigated time-dependent changes. We found that components in a QSS form clusters that grow over time but not in a linear fashion and that this process involves the collapse and regrowth of clusters before the formation of a final large single cluster. These observations might commonly occur in other large-scale biological reaction networks. This developed analysis might be useful for understanding large-scale enzymatic reactions, thereby extracting the characteristics of the reaction network, including phase transitions. As the reconstituted IVT has been used for various applications inducing directed evolution of membrane proteins [2,3], the developed computational model might be useful in further enhancement of the yield of synthesized proteins using the reconstituted IVT. Please click Additional Files below to see the full abstract

Enveloped artificial viral capsids self-assembled from anionic beta-annulus peptide and cationic lipid bilayer

Anionic artificial viral capsids were self-assembled from β-annulus-EE peptide, then complexed with lipid-bilayer-containing cationic lipids via electrostatic interaction to form enveloped artificial viral capsids. The critical aggregation concentration of the enveloped artificial viral capsid was significantly lower than that of the uncomplexed artificial viral capsid, indicating that the lipid bilayer stabilised the capsid structure

Local structural analyses on molten terbium fluoride in lithium fluoride and lithium–calcium fluoride mixtures

X-ray absorption fine structure (XAFS) measurements on terbium fluoride in molten lithium fluoride and in molten lithium–calcium fluoride mixtures, (e.g. 0.20TbF3–0.80LiF, 0.20TbF3–0.62LiF–0.18CaF2, 0.20TbF3–0.48LiF–0.32CaF2, 0.50TbF3–0.50LiF, and 0.50TbF3–0.38LiF–0.12CaF2), have been carried out. In the solid state, coordination number of terbium (Ni) and inter ionic distances between terbium and fluorine in the first neighbor (ri) are nearly constant in all mixtures. In 0.20TbF3–0.80LiF, 0.20TbF3–0.62LiF–0.18CaF2 and 0.50TbF3–0.50LiF mixtures, Ni's decrease from ca. 8 to 6 and ri's also decrease from ca. 2.29 to 2.26 Å on melting. On the other hands, in molten 0.20TbF3–0.48LiF–0.32CaF2 and 0.50TbF3–0.38LiF–0.12CaF2 mixtures, Ni's are slightly larger than 6 and ri's do not change. These facts correspond to the amount of F− supplied by solvent melts, i.e. the effect of CaF2 becomes predominant at bCaF2 > 0.32 in ternary 0.20TbF3–aLiF–bCaF2 mixtures and at bCaF2 > 0.12 in ternary 0.50TbF3–aLiF–bCaF2 mixtures