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Acylium ions, R-C ≡ O +, play a vital role as reaction intermediates in preparatory organic synthesis and, along with their sulfur analogs, R-C ≡ S +, have also been invoked in astrochemical reaction networks to account for the production of (carbon-rich) chain molecules. While in the past some knowledge about the occurence and also kinetics of acylium-/thioacylium ions has been derived through mass spectrometry, comparatively little is known from spectroscopic study going beyond the simplest members of each family, HCO + and HCS + . Here, recent theoretical and spectroscopic studies in the Cologne laboratories are presented.

Carbon atoms can form structures in one, two and three dimensions due to their unique chemical versatility. In terms of thermal conductivity, carbon polymorphs cover a wide range from very low values with amorphous carbon to very high values with diamond, carbon nanotubes and graphene. Schwarzites are a class of three-dimensional fully covalent sp2-bonded carbon polymorphs, with the same local chemical environment as graphene and carbon nanotubes, but negative Gaussian curvature. We calculate the thermal conductivity of a (10,0) carbon nanotube, graphene and two schwarzites with different curvature, by molecular dynamics simulations based on the Tersoff empirical potential. We find that schwarzites present a thermal conductivity two orders of magnitude smaller than nanotubes and graphene. The reason for such large difference is explained by anharmonic lattice dynamics calculations, which show that phonon group velocities and mean free paths are much smaller in schwarzites than in nanotubes and graphene. Their reduced thermal conductivity, in addition to tunable electronic properties, indicate that schwarzites could pave the way towards all-carbon thermoelectric technology with high conversion efficiency. © IOP Publishing and Deutsche Physikalische Gesellschaft.

Carbon atoms can form structures in one, two and three dimensions due to their unique chemical versatility. In terms of thermal conductivity, carbon polymorphs cover a wide range from very low values with amorphous carbon to very high values with diamond, carbon nanotubes and graphene. Schwarzites are a class of three-dimensional fully covalent sp2-bonded carbon polymorphs, with the same local chemical environment as graphene and carbon nanotubes, but negative Gaussian curvature. We calculate the thermal conductivity of a (10,0) carbon nanotube, graphene and two schwarzites with different curvature, by molecular dynamics simulations based on the Tersoff empirical potential. We find that schwarzites present a thermal conductivity two orders of magnitude smaller than nanotubes and graphene. The reason for such large difference is explained by anharmonic lattice dynamics calculations, which show that phonon group velocities and mean free paths are much smaller in schwarzites than in nanotubes and graphene. Their reduced thermal conductivity, in addition to tunable electronic properties, indicate that schwarzites could pave the way towards all-carbon thermoelectric technology with high conversion efficiency. © IOP Publishing and Deutsche Physikalische Gesellschaft.

Physics of ruthenates presents very attractive research field, recently. However, the nature of the ground state of CaRuO3 is not fully explored. Motivation for this study was to explore the influence of small concentrations of nonmagnetic substitutions for Ru4+ (Ti4+, Zr4+, Hf4+) on magnetic properties of material. Magnetic measurements (DC and AC method) show spin glass like magnetic ordering at T < 35 K for Ti4+ doped material, independently of concentration. On the other hand Zr4+ and Hf4+ doped materials show enhanced paramagnetism below 100 K. These results are completely unexpected, since Zr and Hf ions have larger ionic radii than Ti, and consequently produce larger frustration of the crystal lattice. Possible scenario of magnetic ordering of Ti4+ doped material is discussed.

We analyzed the restriction fragment length polymorphism of class I and class II MHC genes in DNA from 20 individuals belonging to the four different species of the complex of species of Balkan mole rats Spalax leucodon captured at four different localities in Yugoslavia. All populations were tested with four restriction enzymes and one conserved mouse probe for each of the two classes of MHC genes. The probes employed detect either limited polymorphism of class I genes or lack of polymorphic bands containing class II genes. Of the two other subterranean rodents that have been studied, four karyotype forms of the Israeli mole rat show polymorphism in both classes of MHC genes similar to the one found in all other mammals (Nižetić et al. 1985), and the Syrian hamster shows limited polymorphism of class I genes and high polymorphism of class II genes (McGuire et al. 1985). Balkan mole rats belong to a new group in this respect, different from all mammals studied so far, since they apparently show limited polymorphism of both classes of MHC genes.