Tissue distribution, elimination and metabolism of [3H]-leukotriene C4 in the American bullfrog, Rana catesbeiana

Tissue distribution, elimination, and metabolism of [3H]-leukotriene C4 were studied at 2.5 hours after injection in the conscious and anesthetized American bullfrog, Rana catesbeiana. Conscious frogs were injected via the dorsal lymph sac or the sciatic vein. Anesthetized frogs were injected via the abdominal vein. The organs containing the greatest percent of injected radioactivity at 2.5 hours after injection were liver, small intestine and kidney. Route of injection and anesthesia appears to alter distribution and elimination of leukotrienes. [3H]-leukotrienes were eliminated into bladder water and bile. In addition, 7.8 +/- 2.2 and 5.2 +/- 2.5 percent of the injected radioactivity was found in the pan water bathing the ventral surface of the venously and dorsally injected conscious frogs, respectively, suggesting transfer of radioactivity across the skin. At 2.5 hours, polar metabolites represented 50% of the radioactivity found in liver, bile, and bladder water. These polar metabolites were determined to be 18-carboxy-19,20-dinor-leukotriene E4, 20-carboxy-leukotriene E4, and 20-hydroxy-leukotriene E4. Of the non-oxidized leukotrienes, bile contained mainly LTD4 while bladder water contained primarily LTE4. N-acetyl LTE4 was not detected in any samples. The tissue distribution, elimination and metabolism of leukotrienes in the bullfrog was similar to mammalian studies and suggests evolutionary conservation of leukotriene processing.     

Mediastinal angiography. A helpful method to evaluate to operability of mediastinal and lung tumors (author's transl)

Preoperative mediastinal angiography, as a simple method, shows alterations of pulmonary and venous mediastinal circulation. It enables the surgeon to evaluate the operability of malignant thoracic neoplasms without performance of other diagnostic procedure with a higher rate of complications, e.g. mediastinoscopy or explorative thoractomy.     

Corrosion protection with zinc-rich epoxy paint coatings embedded with various amounts of highly dispersed polypyrrole-deposited alumina monohydrate particles

Active anodic zinc content below 90 wt.% does not support sufficient electrical contacts but higher contents cause high porosity of traditional liquid zinc-rich paints (ZRPs). To resolve this problem, our proposal is the application of highly dispersed polypyrrole (PPy) coated alumina inhibitor particles (PCAIPs) in zinc-rich paint compositions. Using these nano-size inhibitor particles at concentrations from 4.55 to 0.85 wt.%, hybrid paints were formulated with zinc contents ranging from 60 to 85 wt.% at the same time. Submicron morphology and nano-scale structure, spectroscopy characteristics and electrochemical properties of the PCAIPs were studied by transmission electron microscopy (TEM) and rheology, Fourier-transform infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) in first part of the work. In the second part, electrolytic corrosion resistivity of two sets of paint coatings were salt-spray chamber and immersion tested with 5 wt.% aqueous solution of sodium chloride. Active corrosion prevention ability of the salt-spray tested coatings was evaluated in compliance with ISO recommendations. Dielectric properties of the coatings during the immersion tests were monitored by electrochemical impedance spectroscopy (EIS). Corrosion tested area of the coatings was investigated by glow-discharge optical emission spectroscopy (GD-OES) to disclose infiltration of corrosive analytes and oxygen enrichment in the cross-section of the primers in comparison with their pristine states. Morphology of the zinc pigments was examined by scanning electron microscopy (SEM), and quality of steel specimens and the interfacial binder residues by X-ray photoelectron spectroscopy (XPS) as well as FT-Raman and Mössbauer spectroscopy. The results of both types of corrosion tests evidenced efficient utilisation of sacrificial anodic current for galvanic protection and improved barrier profile of the hybrid coatings, along with the PCAIP inhibited moderate self-corrosion of zinc. As a result of well balanced active/passive function, the hybrid coating containing zinc at 80 wt.% and PCAIPs at 1.75 wt.% embedding PPy at 0.056 wt.% indicated the most advanced corrosion prevention. Galvanic function of the hybrid paints is interpreted on the basis of size-range effect and spatial distribution of the alumina supported PPy inhibitor particles and basic electrical percolation model considerations.     

Ultrasonic on-machine measurement for internal topographies

The integration of metrology into the manufacturing process is becoming increasingly important for production technology. The measurement directly on machine tools is especially improving manufacturing strategies. So far, optical or tactile measuring systems are the state-of-the-art for dimensional measurements in process metrology. However, the wall thickness of structures with inner cavities cannot be measured with these systems. Owing to these deficits, an ultrasonic system was integrated into the peripheral equipment of a machine tool. Both the extensive signal processing of the acoustic echoes and the developed software tool ' w -sonic' are discussed. The aim is to show the potential of the ultrasonic in-line measurement. A practical application for the individual machining of gas cylinders and initial results are also presented.     

Sub-nanometer characterization of activated carbon by inelastic neutron scattering

Inelastic neutron scattering spectra are calculated for hydrogen molecules adsorbed on activated carbon. The slit-shaped pore model is used to calculate the adsorption potentials of a hydrogen molecule in pores of variable width. The motion of the hydrogen molecules is quantized perpendicular to the plane of the pore and both rotational and vibrational transition energies are found. The perturbation of adjacent hydrogen molecules on the transition energies is discussed. Form factors and Debye–Waller factors are calculated for momentum transfer parallel and perpendicular to the pore; this anisotropy is particularly pronounced in pores where there is nearly enough room for two adsorbed layers. A spectrum composed of a uniform distribution of pore sizes agrees only qualitatively with experimental results for activated carbon. Reasons for this disparity are discussed, including the possibility that transitions in the translational motion parallel to the adsorption plane contribute significantly to the spectra. In addition, the positioning of the center of gravity of the first rotational transition is discussed, with several factors contributing to shift it from the 14.7 meV of the gas phase. Our results suggest that inelastic neutron scattering can be valuable as a complementary sub-nanometer pore characterization technique.     

Lichtinitiierte Polymer- und Polymerisationsreaktionen. III. Photoinduzierte Zersetzung von Aryldiazoniumsalzen durch Benzoinderivate

Light Induced Polymer and Polymerization Reactions. III. Photoinduced Decomposition of Arene Diazonium Salts by Benzoin Derivatives The combination benzoin derivate/arene diazonium salt is suitable as a bivalent photoinitiator system for radicalic and cationic photopolymerization. By means of product analysis, quantum yield measurements and photo-CIDNP-studies a mechanism was proposed including the electron transfer from α-substituted benzyl radicals formed by benzoin derivate photolysis to arene diazonium salts. The quantum yields for diazonium salt decomposition in acetonitril were about 0.65. They show only a small dependence on substituents of diazonium salt but are strong influenced by the solvent. In methanol or dioxane quantum yields were found from 11 to 460. ¹³C-photo-CIDNP-measurements agree with a mechanism of benzoin ether photolysis on the triplet state.     

Die Kämpf‐Stegträger der Eissporthalle Bad Reichenhall – Eine typische Holzkonstruktion der 1950er und 1960er Jahre?

A typical timber construction of the 1950's an 1960's? Kämpf‐web‐girders like the one of the ice rink in Bad Reichenhall have been used frequently, wether mostly in smaller dimensions, in the 1950's and 1960's. They are an example for the great efforts that have been made in research and practice to establish definitely the glued wood construction in timber engineering. At the latest by the end of the 1960's this aim was achieved. Nevertheless, the beginning of the glued wood construction has already been made half a century before by Otto Hetzer and others. The history of the development of the glued laminated timber is a typical example, that the so‐called process of diffusion – from innovation up to the point of general distribution and application of an innovation – especially in civil engineering often takes one or two generations.