Investigation of energetic heterogeneity of carbon black surfaces during adsorption of chromatographically low concentrations of n-pentane

Energetic heterogeneity of different types of industrial carbons was studied by gas-adsorption chromatography in regions of low surface coverages. The main thermodynamic characteristics of n-pentane adsorption on the carbon black surfaces were experimentally determined under the conditions close to the zero coverage of the surface (Henry region). These characteristics include the Henry constants, differential molar heats of adsorption, changes in the entropy of adsorption, and differences in molar heat capacities of the adsorbate in the adsorbed state and its vapors at a constant pressure. The specific features of the geometric structure and ratio of surface regions different in the adsorption energy make it possible to establish the presence of the Henry region in the adsorption isotherm. The gas-chromatographic criteria, which can be used to estimate the degree of energetic heterogeneity of the adsorbent surface, were considered.     

Synthesis and photophysics of a linear non-covalently linked porphyrin-fullerene dyad

The synthesis and characterization of a new pyridinofullerene ligand capable of forming axially symmetric complexes with ZnTPP is reported; molecular modelling studies, 1H NMR, UV-Vis spectroscopy and fluorescence quenching data support formation of a strong complex between the new ligand and ZnTPP.     

Measurement of heat transfer coefficient and axial dispersion coefficient using temperature oscillations

A periodic transient test technique based on the axial dispersion model is proposed for the determination of both heat transfer coefficients and axial dispersion coefficients in heat exchangers. The model uses a parameter called the axial dispersive Peclet number to account for the deviation of the flow pattern from ideal plug flow. It takes both axial dispersion in the fluid and axial heat conduction in the wall into account and is solved analytically by means of a complex Fourier transform. Experiments conducted on dented copper tubes show that axial dispersion has a significant effect on the dynamic temperature response of a heat exchanger.     

Finitely extensible bead spring chains in time-dependent shear flows

The configurational and rheological properties of bead spring chains in time-dependent shear flows are calculated. The finite extensibility is incorporated through the constraint of constant contour length of the chain. Start-up of shear flow yields a stress overshoot, whereas oscillatory shear flow yields the same frequency dependence of the dynamic moduli as the simple bead spring model. The results show that finite extensibility can lead to non-linear rheological behavior of dilute polymer solutions. The influence of preaveraged hydrodynamic interaction on the obtained results is discussed.     

On kinematic coupling equations within the scaled boundary finite-element method

The scaled boundary finite element method is a semi-analytical analysis technique, which combines the advantages of the finite element method and the boundary-element method. Assuming that the geometry of the governing structure can be represented by mapping its boundary with respect to the so-called scaling coordinate, the problem can be handled in a closed-form analytical manner in the scaling direction and by a finite-element approximation in the other directions. Thus, a discretization of the boundary is sufficient and the nodal degrees of freedom are functions of the scaling coordinate. In some situations, such as the analysis of the free-edge effect in laminated plates, it is useful to introduce kinematic coupling equations, which are valid not only on the boundary, but also within the domain. The implementation of linear kinematic coupling equations within the method is presented for the case of a three-dimensional structure with scaling in a fixed Cartesian direction. Rigid-body modes are handled by using the concept of generalized inverse matrices. In some benchmark examples the efficiency of the approach is demonstrated and comparison with the results of the finite-element method shows good accordance.     

Convolutions and multiplier transformations of convex bodies

Rotation intertwining maps from the set of convex bodies in into itself that are continuous linear operators with respect to Minkowski and Blaschke addition are investigated. The main focus is on Blaschke-Minkowski homomorphisms. We show that such maps are represented by a spherical convolution operator. An application of this representation is a complete classification of all even Blaschke-Minkowski homomorphisms which shows that these maps behave in many respects similar to the well known projection body operator. Among further applications is the following result: If an even Blaschke-Minkowski homomorphism maps a convex body to a polytope, then it is a constant multiple of the projection body operator.

     

Pharmacophore modeling and parallel screening for PPAR ligands

We describe the generation and validation of pharmacophore models for PPARs, as well as a large scale validation of the parallel screening approach by screening PPAR ligands against a large database of structure-based models. A large test set of 357 PPAR ligands was screened against 48 PPAR models to determine the best models for agonists of PPAR-alpha, PPAR-delta, and PPAR-gamma. Afterwards, a parallel screen was performed using the 357 PPAR ligands and 47 structure-based models for PPARs, which were integrated into a 1537 models comprising in-house pharmacophore database, to assess the enrichment of PPAR ligands within the PPAR hypotheses. For these purposes, we categorized the 1537 database models into 181 protein targets and developed a score that ranks the retrieved targets for each ligand. Thus, we tried to find out if the concept of parallel screening is able to predict the correct pharmacological target for a set of compounds. The PPAR target was ranked first more often than any other target. This confirms the ability of parallel screening to forecast the pharmacological active target for a set of compounds.     

A Constructive Look at Generalised Cauchy Reals

We investigate how nonstandard reals can be established constructively as arbitrary infinite sequences of rationals, following the classical approach due to Schmieden and Laugwitz. In particular, a total standard part map into Richman's generalised Dedekind reals is constructed without countable choice.     

Die magnetischen Eigenschaften der Alkalimetall‐Manganpnictide KMnP,RbMnP, CsMnP,RbMnAs, KMnSb,KMnBi, RbMnBi und CsMnBi – Neutronenbeugungsuntersuchungen und Suszeptibilitätsmessungen

The Magnetic Properties of the Alkali Metal Manganese Pnictides KMnP, RbMnP, CsMnP, RbMnAs, KMnSb, KMnBi, RbMnBi, and CsMnBi – Neutron Diffraction and Susceptibility Measurements In order to determine the spin structures and the magnetic moments of the manganese atoms neutron diffraction experiments and susceptibility measurements were performed on the alkali metal manganese pnictides KMnP, RbMnP, CsMnP, RbMnAs, KMnSb, KMnBi, RbMnBi, and CsMnBi. All compounds order antiferromagnetically. For KMnBi and KMnSb the spin structures may be described in the crystallographic unit cells and Shubnikov group P4'/n'm'm. For the other compounds the lattice constants c have to be doubled, and the Shubnikov group is P4'/n'cc'. With these results it is possible to analyse the correlation between magnetic moments and crystallographic parameters for the complete series of compounds AMnX with A = Na, K, Rb or Cs and X = P, As, Sb or Bi.     

Synthese und Kristallstrukturen von (NEt4)2[TeS3], (NEt4)2[Te(S5)(S7)] und (NEt4)4[Te(S5)2][Te(S7)2]

Synthesis and Crystal Structures of (NEt₄)₂[TeS₃], (NEt₄)₂[Te(S₅)(S₇)], and (NEt₄)₄[Te(S₅)₂][Te(S₇)₂] (NEt₄)₂[TeS₃] was obtained by the reaction of NEt₄Cl, Na₂S₄ and tellurium in acetonitrile. It reacts with sulfur, yielding (NEt₄)₂[Te(S₅)(S₇)], which is transformed to (NEt₄)₄[Te(S₅)₂][Te(S₇)₂] by recrystallization from hot acetonitrile. According to the X-ray structure analysis, crystals of (NEt₄)₂[TeS₃] are monoclinic (space group P2₁/c) and form twins with the twinning plane (001); they contain pyramidal TeS₃^2– ions. (NEt₄)₂[Te(S₅)(S₇)] forms triclinic twins (space group P1) with the twinning plane (010). In the [Te(S₅)(S₇)]^2– ion an S₅ and an S₇ atom group are bonded in a chelate manner to the tellurium atom, which has square coordination. (NEt₄)₄[Te(S₅)₂][Te(S₇)₂] (monoclinic, space group P2₁/c) contains two kinds of anions, the known [Te(S₅)₂]^2– and the new [Te(S₇)₂]^2– ion which has two S₇ chelating groups.