Untersuchungen über Chelidonsäure

Ohne Zusammenfassung     

Some problems with determination of alpha-active nuclides during decommissioning of nuclear power plant A-1

The first step in decommissioning of NPP is connected with defueling and successful disposal of liquid radioactive wastes (LRW), both from previous production and all work connected with this step. These require precise knowledge about the concentration of radioactive nuclides presented, especially alpha-emitters in all material fluxes arising in sich work (namely shut-down after some accident). This paper reports, results of the determination of U, Pu, Am and Cm by means of both the commonly used and the newly developed radiochemical procedures in various types of materials, e.g., LRW, aerosol filters, ashes resulted from incineration technology, metal surfaces, decontamination solutions etc.     

Hartree—Fock—Slater-LCAO studies of the acetylene—transition metal interaction. III. Binding to mono- and dinuclear Ni complexes with carbonyl and isocyanide ligands

The bonding of C₂H₂ in the nickel complexes [π-(C₂H₂)Ni(CO)₂], [π-(C₂H₂)Ni(CNH)₂] and [μ₂-(C₂H₂) {NI(CNH)₂}₂] has been studied by the non-empirical self-consistent Hartree—Fock—Slater-LCAO method. Calculations have been performed, not only for these complexes, but also for free C₂H₂ and its substituted analogues, propyne, but-2-yne and hexafluorobut-2-yne, and for the mono- and dinuclear complex fragments, [Ni(CNH)₂] and [{NI(CNH)₂}₂], which interact with the C₂H₂ molecule. The main difference with nickel surfaces, which have analogous π and μ₂ adsorption sites for C₂H₂ that we have studied by the same method, is the much stronger 3d, 4s, 4p hybridization induced by the CNH and CO ligands. In the bis(diisocyanide—nickel) complex these hybrids form a rather broad dsp “band”. The low lying occupied levels in this “band” cause a strong interaction with the filled acetylene π_u orbitals which dominates the π to metal donation effect. In the mononickel—acetylene complex this donation does occur, however, just as for acetylene adsorbed on nickel surfaces (in combination with the more prominent metal to π^* back donation which we find in all cases). A linear relation has been derived between the CC stretch frequencies in coordinated C₂H₂ molecules and the calculated CC overlap populations. Substitutio of the H atoms in (free) C₂H₂ by CH₃ or CF₃ groups has almost no effect on the CC overlap population and force constant.     

Bücherbesprechungen

Ohne Zusammenfassung     

Construction of free continuous algebras

A subset system Z is a function, assiging to each posetX a collectionZX of its subsets. We studyZ-continuous universal algebras, i.e., ordered algebras such that their domains have, and their operations preserve, joins of allZ-sets. A construction of the freeZ-continuous algebras is exhibited for an arbitraryZ. It turn out that only four subset systems have to be considered: the systemZX of (i) all ε-chains inX; (ii) all finite subsets ofX; (iii) all countable subsets ofX and (iv) the void set alone. The free algebras are described concretely for these four cases.     

Примечание к изучени ю изменений структур ы материала при усталости

---

Contribution to the study of fatigue material deformation structure

     

Diffusion-controlled mode coupling in two-dimensional antiferromagnets: EPR linewidth

We present the first realistic mode-coupling calculation of the high-temperature EPR linewidth of a two-dimensional antiferromagnet. The theory is valid for temperatures where the linewidth is determined by diffusion-controlled dynamics. The angular and temperature dependence of the linewidth are in good agreement with experiment, although the absolute values are somewhat too small (∽40%).     

Atomic XAFS as a tool to probe the electronic properties of supported noble metal nanoclusters

Atomic XAFS is a very attractive technique for probing electronic properties of supported metal nanoclusters. For platinum nanoparticles on different supports, the technique is found to be in good agreement with infrared CO adsorption measurements. The advantages of AXAFS, however, are that no probe molecule is required and that real-time measurements under reaction conditions are possible.     

Replacement substoichiometry and its application in activation analysis

A new method based on the substoichiometry principle has been developed. Instead of substoichiometric amounts of chelating agent, substoichiometric amounts of aqueous solution of a competing metal are used. Theoretical relationships have been derived for this method of substoichiometric replacement. Possibilities for its application are discussed.     

Vibrational spectra of 2-furaldehyde

The infrared spectra of 2-furaldehyde and its deutero analog were measured in the gaseous and liquid states and in solutions. The band contours of the spectra of the gaseous phase were discussed. Normal coordinate calculations were carried out and related to the band assignment.