Strukturelle Charakterisierung der Dicyanamid-Komplexe von Kupfer(II), Nickel(II) bzw. Kobalt(II) mit Aminopyridinen

Summary New dicyanamide complexes of the typeM[N(CN)₂]₂ L ₂ (M=Cu or Ni;L=2-, 3-, 4-aminopyridine, 2-amino-5-nitropyridine) and Co[N(CN)₂]₂ (2-amino-5-nitropyridine)₂ were prepared and studied by spectroscopic methods as well as by room-temperature magnetic moments. The results show that the Cu(II) complexes have elongated pseudooctahedral structures while the Ni(II) and Co(II) complexes are octahedral. In most cases the N(CN)₂ groups are in bridging function and through their cyanide nitrogens, or-more rarely-amide and cyanide nitrogens connect the basic structure units into polymeric conglomerates. In the Cu(II) systems exchange coupling is seen from the _eff value or ESR spectrum.

Professor Viktor Gutmann zum 70. Geburtstag gewidmet     

Large-area boron carbide protective coatings for controlled thermonuclear research prepared byin situ plasma CVD

Impurity release from the first wall and components facing the hot plasma in Tokamak devices for controlled fusion research and the concomitant pollution of the plasma lead to enhanced energy losses and deuterium-tritium luel dilution. Both these effects can prevent reaching the ignition conditions. The recently developed technique for large areain situ deposition of boron carbide protective coatings by means of plasma-induced chemical vapor deposition enables one to significantly improve the purity of the fusion plasma. The prospects of approaching the scientific break-even in the large machines of the Tokarnak type has been increased.Extended version of an invited paper presented at the 10th International Symposium on Boron, Borides, and Related Compounds, Albuquerque, New Mexico, August 1990.The term Tokarnak is an abbreviation of the Russian name toroidal magnetic chamber.     

Unified quantum logic

Unified quantum logic based on unified operations of implication is formulated as an axiomatic calculus. Soundness and completeness are demonstrated using standard algebraic techniques. An embedding of quantum logic into a new modal system is carried out and discussed.On leave of absence from Department of Mathematics, University of Zagreb, Pot. Pret. 165, YU-41001 Zagreb, Yugoslavia.     

On the tensor product of supersingleton representations ofosp(1, 2n)

The tensor product of two supersingleton representations _n of the Lie superalgebraosp (1, 2n) is studied forn2. The main results are as follows: (a) anticommutators and commutators of the odd generators in _{n n} form a skew-symmetric representation of the Lie algebrau(n, n); (b) simple explicit form of all irreducible components of _{n n}, which are labelled by a single parameterJ=0, 1, ..., has been found. Each of them is a^*-representation ofosp (1, 2n) for which assertion (a) is valid. The dimension of its vacuum subspace equals , i.e., the nondegenerate vacuum occurs for J=0 only. Basic property of this family of irreducible^*-representations of osp(1, 2n) are analogous to those of massless representations of osp(1, 4).Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday.     

Quantitative characterization of chaotic instabilities in semiconductors

A method for quantitative characterization of chaotic dynamical systems is discussed. An electronic instrument for determining the number of independent variablesk ^*, involved in the motion, is described. It allows one to obtain these in real time from a single observable. The suggested technique has been applied to quantification of strange attractors underlying chaotic instabilities in semi-insulating GaAsCr, and n-Ge, irradiated with high energy electrons. In n-Ge, for instance, the measured numbersk ^* range from 2 to 4 depending on control parameters. These measurements reveal the highly deterministic nature of the observed chaotic oscillations. The physical mechanisms responsible for the current instabilities and chaotic behaviour are discussed.     

Reliable evaluation of temperature-independent parameters in correlation of vapour–liquid equilibrium data

A new algorithm/program has been elaborated for simultaneous processing of different sets of vapour–liquid equilibrium data. The program was tested with six binary hexane + isomeric pentanol systems, each of them measured at three different isobaric conditions and one isothermal system of tert-butyl-methyl-ether + 2-methyl-2-propanol measured at three different temperatures. The correlation uses the maximum likelihood method, taking into account real behaviour of vapour phase. The parameters obtained are valid within the whole temperature range of the data, and are consistent in comparison with those obtained from individual correlations of isobars or isotherms. Results are presented for the Wilson and NRTL equations.     

Solvent effects on the redox properties of tris-(1,10-phenanthroline)iron(II/III) complexes

The redox properties of the system Fe(tmphen)₃(II/III) (tmphen=3,4,7,8-tetramethyl-1,10-phenanthroline) have been studied in the solvents nitromethane, acetonitrile, propanediol-1,2-carbonate, dimethylformamide, dimethylacetamide, dimethylsulfoxide and of the systems Fe(phen)₃(II/III) (phen=1,10-phenanthroline) and Fe(niphen)₃(II/III) (niphen=5-nitro-1,10-phenanthroline) in the solvents nitromethane, acetonitrile, propanediol-1,2-carbonate and acetone. The redox potentials of Fe(tmphen)₃(II/III) are nearly independent of the solvent suggesting that the system might be used as a reference redox couple similar to the systems ferrocene/ferricinium or bisbiphenylchromium(0/I). In contrast the redox potentials of Fe(niphen)₃(II/III) show a significant decrease with increasing donor number of the solvent which can be explained by nucleophilic attack of solvent molecules at the iron. It is shown that such a mechanism is consistent with the known solvent and salt effects on the kinetics of dissociation of ferroin and ferriin type complexes.     

Einige Gesetzmäßigkeiten der spontanen Umwandlung der Wasserstofform des Montmorillonits in die Aluminium-form

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