The Fermi doublet V2−V3 + V4 of CH3CN as a probe of molecular interactions

The Fermi doublet V₂?V₃ + V₄ of CH₃CN in basic, inert and acidic solvents has been studied by IR and Raman spectroscopy. The values of W, the Fermi coupling coefficient, obtained from IR spectra varies with the nature of the solvent while W evaluated from Raman data remains constant at 12.5 ± 0.5 cm^?1. The similar effects of Bronsted and Lewis acids on the band frequencies and intensities is evidence that the CN group complexes with acids via the N atom “n” electron pair and not the π bond.     

Confidence intervals for calibration with neural networks

Based on neural network calibration the confidence intervals of aromaticity determination from infrared reflectance spectra of raw brown coals were estimated by means of the bootstrap method, a simplified Monte Carlo Simulation. The standard deviations and the confidence intervals were estimated to characterise the analysis error.It is shown that confidence intervals of non-linear analysis methods like Back Propagation Neural Networks (BPNN) can be estimated by the bootstrap method. The estimated confidence intervals of the calibration confirm the analysis by BPNN.     

Structure of the OD-disordered 2-Hydroxy-4-methoxy-2H-1,4-benzoxazin-3-one,C9H9NO4

The X-ray diagrams of the title compound show pronounced maxima on diffuse streaks parallel c* and unusual extinctions. The intensity distribution is compatible with the assumption of a disordered (OD) structure consisting of one kind of layers. The structure contains ordered domains with the crystal data: monoelinic, space group P 2₁/a, lattice parameters a = 15.910(5), b = 8.365(4), c = 15.747(5) Å, β = 120.34(6)°, V = 1809 ų, Z = 8, M_r = 195.1, D_x = 1.432 Mg m⁻³, μ(MoKα) = 0.36 mm⁻¹, final R = 0.129 for 859 observed reflections. The asymmetric unit is constituted of two crystallographically independent molecules related by a pseudo glide plane. The crystal used for X-ray analysis proved to be twinned.     

Noncovalent immobilized artificial membrane chromatography, an improved method for describing peptide-lipid bilayer interactions.

A promising approach in assessing hydrophobic peptide-membrane interactions is the use of reversed-phase high-performance liquid chromatography. The present study describes the preparation and properties of a noncovalent immobilized artificial membrane (noncovalent IAM) stationary phase. The noncovalent IAM phase was prepared by coating the C18 chains of a reversed-phase HPLC column with the phospholipid ditetradecanoyl-sn-glycero-3-phosphocholine. Lipid coating was achieved by pumping a lipid solution in water-2-propanol through the column. The formation of a bilayer-like structure on the chromatographic surface was confirmed by calculating the phospholipid surface density of the stationary phase. The surface density was determined to be approximately 1.95 mumol m-2, which is close to that of lipid vesicles. The coating was found to be stable in chromatographic elution systems containing less than 35% of acetonitrile. Employing this new technique, we determined interaction parameters of a set of helical antibacterial magainin-2-amide peptides with pairwise substitutions of adjacent amino acids by their D-enatiomers. The results demonstrate that the chromatographic retention behavior of peptides on noncovalent IAM stationary phase shows an excellent correlation with lipid affinities to phospholipid vesicles.     

Systemoptimierung im Netzwerk zur Unterstützung der Personalplanung

Zusammenfassung Personalfluktuationen und Beförderungen in einem aus homogenen Gruppen bestehenden hierarchischen Personalsystem können als Übergänge in einem Netzwerkmodell dargestellt werden. Die Übergangsraten kann man mit Kostenfunktionen verknüpfen, die den Zielen der Personalplanung entsprechen. Die Ermittlung einer kostenminimalen Beförderungsstruktur im Netzwerk läßt sich auf die Lösung des klassischen Transportproblems zurückführen. Durch Berücksichtigung der Wechselwirkungen im Personalsystem — insbesondere zwischen Beförderungsund Fluktuationsstruktur — erreicht man eine schrittweise Annäherung an das Gesamtoptimum.

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Summary Fluctuations and promotions in a hierarchical personell system which consists of homogenous groups can be represented by the arrows of a network model. To be attached to the transfer rates of the network are e.g. cost functions which are in accordance with the personell planning objectives. The determination of a promotional structure for minimum cost is reduced to the solution of the classical transport problem. Considering the interdependence within the personell system, e.g., between promotional structure and fluctuation structure, leads to a stepwise approximation to the global optimum.

     

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Fabrication of micro-patterned substrates for plasmonic sensing by piezo-dispensing of colloidal nanoparticles

Analytical and Bioanalytical Chemistry - In this work we describe a very fast and flexible method for fabrication of plasmon-supporting substrates with micro-patterning capability, which is...     

On the trapping of SOx on CaO-Al2O3-based novel high capacity sorbents

Calcium-aluminum mixed oxide based materials doped with Na and Mn were explored as sulfur trapping materials. The materials showed a three times higher total storage capacity and a higher time on stream with complete SO2 removal compared to a second generation SOx trapping material which was mesoporous with calcium mainly present in oxidic form. Combining in situ XANES at the S K-edge and IR spectroscopy the key properties of the storage materials and the affiliated storage processes were identified. CaO-Al2O3 acts as the primary support and storage component, while Na+ cations adjust the base strength and enhances the storage capacity. Manganese cations provide the appropriate oxidation capacity in absence and presence of up to 10% water. The transport into the bulk phase, which is markedly influenced by a layer of sorbed water, is the rate-limiting step in presence of Mn cations. In the absence of manganese cations the oxidation step appears controlling the rate. The overall reaction network, identified by in situ IR spectroscopy and the 2D Correlation Analysis, is similar on all materials.     

SO(x) storage materials under lean-rich cycling conditions. Part I: Identification of transient species

The SO(x) uptake of second generation sulfur trapping materials was studied by in situ IR spectroscopy under lean-rich cycling conditions. The combination of advanced chemometric methods including generalized 2D correlation analysis, 2D sample-sample correlation analysis, and multivariate curve resolution with alternating least squares allowed the detection of the species involved in the storage process. The formation of the bulk sulfate species was always accompanied by the consumption of carbonates. The reduction of a transient surface sulfate species was identified as the key parameter in the storage process under dynamic conditions. Three distinct reaction regimes were differentiated on the industrial materials under SO(x) trapping conditions being imperceptible from conventional spectra.