Noncoassociative twisting: Its application to κ-Poincaré algebra

It is shown that the use of noncoassociative coproduct allows us to simplify the structure of-Poincaré algebra — it contains nondeformedD=3 Euclidean quasi-bialgebra. We obtain by the dual construction the commuting, nonassociativeD=4 space-time.Presented at the 4th international Colloquium Quantum Groups and Integrable Systems, Prague, 22–24 June, 1995I would like to thank Profs. J. Lukierski and V.N. Tolstoy for valuable comments.     

Synthesen und Eigenschaften von Tris(perfluoralkyl)arsen- und -antimon(III,V)-Verbindungen

Preparations and Properties of Tris(perfluoroalkyl) Arsenic and Antimony(III, V) Compounds As(R_f)₃ and Sb(R_f)₃ (R_f?C₂F₅, C₄F₉, C₆F₁₃) are prepared in good yields by the polar reactions of AsCl₃ and SbCl₃ with bis(perfluoroalkyl) cadmium compounds as colourless liquids or solids. The oxidation of As(C₂F₅)₃ and Sb(C₂F₅)₃ with XeF₂ gives the difluorides M(C₂F₅)₃F₂ (M?As, Sb). As(C₂F₅)₃Cl₂ is prepared by chlorination of As(C₂F₅)₃ in the presence of AlCl₃, while Sb(C₂F₅)₃Cl₂ is formed in the reaction of Sb(C₂F₅)₃F₂ with (CH₃)₃SiCl. During the reaction of M(C₂F₅)₃F₂ with (CH₃)₃SiBr ¹⁹F-NMR spectroscopic evidence is found for M(C₂F₅)₃ Br₂. The thermal decompositions of M(C₂F₅)₃F₂ mainly yield C₄F₁₀ and M(C₂F₅)F₂, while the thermal decompositions of M(C₂F₅)₃Cl₂ yield M(C₂F₅)₂Cl and C₂F₅Cl. The properties and spectroscopic data of the new compounds are described.     

Combustion synthesis as a novel method for production of 1-D SiC nanostructures

1-D nanostructures of cubic phase silicon carbide (beta-SiC) were efficiently produced by combustion synthesis of mixtures containing Si-containing compounds and halocarbons in a calorimetric bomb. The influence of the operating parameters on 1-D SiC formation yield was studied. The heat release, the heating rate, and the chamber pressure increase were monitored during the process. The composition and structural features of the products were characterized by elemental analysis, X-ray diffraction, differential thermal analysis/ thermogravimetric technique, Raman spectroscopy, scanning and transmission electron microscopy, and energy-dispersive X-ray spectrometry. This self-induced growth process can produce SiC nanofibers and nanotubes ca. 20-100 nm in diameter with the aspect ratio higher than 1000. Bulk scale Raman studies showed the product to be comprised of mostly cubic polytype of SiC and that finite size effects are present. We believe that the nucleation mechanism involving radical gaseous species is responsible for 1-D nanostructures growth. The present study has enlarged the family of nanofibers and nanotubes available and offers a possible, new general route to 1-D crystalline materials.     

Vibrational and structural analysis of (hydroxypyridin-3-yl-methyl)phosphonic acid

In this work the vibrational analysis of (hydroxypyridin-3-yl-methyl)phosphonic acid (MC5) is presented using both experimental and theoretical methods. FT-IR spectra of the solid state MC5 precipitated at certain pH values in which consecutive deprotonations of this ligand occurs were recorded. Thus, we were able to measure IR spectra of cationic, two anionic and zwitterion forms of MC5. Additionally, the geometry optimization and vibrational frequencies were performed at the B3PW91 level with the 6-31G** basis set for each species. As was shown, FT-IR spectra could be fairly good reproduced by a theoretical method applied here. Additionally, charge distributions and aromaticity index were calculated for discussed MC5 forms by using generalized atomic polar tensor and harmonic oscillator model of aromaticity, respectively.     

2‐Aminopyrimidine–3,3,3‐triphenylpropanoic acid (1/1)

The title bimolecular compound, C₄H₅N₃·C₂₁H₁₈O₂, constructed from 2‐aminopyrimidine and 3,3,3‐triphenylpropanoic acid, forms a tetramolecular hydrogen‐bonded motif via O—H...N, N—H...O and N—H...N contacts. This aggregate organizes to give crystal‐packing motifs with hydrophilic and hydrophobic regions.     

Optimal control methods applied on the ionization processes of alkali dimers

We present two novel optimization methods by employing shaped fs-laser pulses in a closed feedback loop. The first describes control pulse cleaning where extraneous features were removed by applying genetic pressure on certain pulse components. The second reports parametric optimization with intuitive parameters such as subpulse distances, chirps, phase differences, and spectral peak patterns. These methods were conducted on the ionization process of alkali dimers produced in a molecular beam and improved the performances of the optimized pulses compared with short pulses at the same pulse energy. Moreover, we attempt to analyze the obtained pulse shapes regarding the underlying optimized processes. Further investigations concerning isotope selective fragmentation and optimal control of excitation processes of ultracold rubidium dimers in a magneto-optical trap (MOT) are also shown.     

Cyclization of o-acylphenylacetic acids to 1-aryl-3-hydroxyisoquinolines

Methyl o-acylphenylacetates react with urea to give 1-aryl-3-hydroxyisoquinolines. 1-Phenyl-2-methyl-3-isoquinolone was obtained by the action of methylamine on methyl o-benzoylphenylacetate. The lactim-lactam tautomerism of 1-aryl-3-hydroxyisoquinolines is discussed on the basis of their UV and IR spectra. The biological activity of some 1-aryl-3-hydroxyisoquinolines with respect to 16 strains of bacteria was studied.