Schmelzen von Eisenschwamm mit Brennerflammen

Erörterung der Rückoxidationsprobleme beim Einschmelzen von Eisenschwamm mit Rauchgasen aus fossilen Brennstoffen. Erwärmen und Schmelzen unter isothermen und simulierten Bedingungen im Schachtofen. Diskussion von Schutzmaßnahmen und Vorstellen von Versuchsergebnissen zur Verhinderung der Rückoxidation.     

Untertagevergasung tiefliegender Steinkohle

Bisherige Entwicklungen zur Untertagevergasung von Kohle. Neuere Überlegungen zur Untertagevergasung in Anlehnung an die Methoden bei der Gewinnung von Erdöl und Erdgas. Erörterung über die Verfahren des Bohrlochbergbaus im Durchdringungsverfahren, Kanalverfahren und Blockumströmungsverfahren. Beurteilung der Möglichkeiten der Untertagevergasung bei tiefliegenden Steinkohlelagerstätten. Bericht über die Aktivitäten einer Arbeitsgruppe des Instituts für Eisenhüttenkunde der Technischen Hochschule Aachen mit Angaben über Versuche im Autoklaven zur Simulation der Untertagevergasung und zur Ermittlung grundlegender Stoffdaten. Beurteilung der Zukunftsaussichten der Untertagevergasung.     

Industrieller Korrosionsschutz „Duplex-System”︁: Feurerverzinkung plus Kunststoffbeschichtung am Beispiel von Stahlrohr-Durchlässen

Protection against Corrosion in the Industry by ”?Duplex-System”?: Hot-Galvanization Plus Plastic-Coating on Steel-Pipe Passages The authors reports on the manufacture and economic application of hot-galvanized and plastic-coated steel-parts as pipe passages for road construction and underground construction. The advantages of the Duplex-System, i. e. hot-galvanization and plastic-coating, as a modern corrosion-protective measure against fluctuating chemical stress, mechanical wear and tear, and stress due water-leakage are shown. The plastic layer, consisting of a modified two-component epoxy-resin, is applied in a continuous spray-painting plant by the airless-spraying process to yield a 150 μ dry-film layer, which is then stoved in a circulating air-oven. Illustrations are presented to depict the coating process in the spray-painting plant and to show the transport as well as application of hot-galvanized, plastic-coated steel parts as pipe-passages.     

Zu den Ersatzschaltungen für kurze Leitungen

Übersicht Es werden der Näherungscharakter der für kurze Leitungen üblichen Ersatzschaltungen und damit die Leitungslängen, bis zu denen man die Schaltungen unter Forderung einer bestimmten Genauigkeit anwenden kann, ermittelt. Gleichzeitig wird die physikalische Bedeutung der Ersatzschaltungen erörtert. Untersucht wird einerseits die Darstellung der Leitung nur durch ihren Längswiderstand, andererseits die zusätzliche Berücksichtigung des Querleitwerts durch Konzentration in der Leitungsmitte oder je zur Hälfte an den beiden Leitungsenden.

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Summary The approximative character of the equivalent circuits commonly used for short transmission lines is investigated. By this a certain length of the line can be specified, upto which the equivalent circuits may be used with a given accuracy. In connection the physical significances of the equivalent circuits are discussed. The representation of a transmission line but by the series impedance and the improved representation considering the shunt admittance by lumping in the middle of the line or in equal parts on the ends of the line, are explicitly considered.

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Mitteilung aus dem Rogowski-Institut für Elektrotechnik der Rhein.-Westf. Technischen Hochschule Aachen     

Effects of silibinin and antioxidants on high glucose-induced alterations of fibronectin turnover in human mesangial cell cultures

To elucidate the primary mechanism of high glucose cytotoxicity, the cytoprotective properties of antioxidants against metabolical disorders were assessed in human mesangial cell (HMC) cultures. An 8-day incubation of HMC with high glucose concentration (30 mM) resulted in an extracellular accumulation of the matrixprotein fibronectin (FN), owing to both an expansion of the matrix-associated pericellular FN and a 60% increase of the soluble molecule in the culture medium. The high glucose-induced FN alterations were not due to osmotical effects, as assessed by an iso-osmotic mannitol control. Rather, they are mediated by oxygen-free radicals because the combined treatment of HMC with high glucose and either the antioxidative flavonoid silibinin (given as the water soluble derivative silibinin-C-2,3-dihydrogensuccinate disodium salt) or a radical scavenger cocktail totally prevented the extracellular FN accumulation. This is corroborated further by the determination of malondialdehyde, a product of lipid peroxidation. Incubation of HMC with high glucose resulted in an increase of malondialdehyde in cell homogenates which was completely counteracted by either silibinin or a radical scavenger cocktail. Silibinin alone had no effects on protein synthesis and culture growth. The data presented are compatible with oxidative stress induced by high glucose concentration in HMC cultures. The study further substantiates the proposed role of silibinin in the amelioration of glucose cytotoxicity in renal cells.     

Narrow Vertical Far-Field 975-nm Broad-Area DFB Lasers for Wide Temperature Range Operation

We report on 100-mum-wide 975-nm distributed-feedback lasers with a cavity length of 2 mm, which deliver 2.4 W within a 14deg vertical far-field angle (full-width at half-maximum) and 35% power conversion efficiency in combination with a spectral linewidth of 0.27 nm (95% power content). The epitaxial design is a compromise between a narrow vertical far-field and a good power conversion efficiency, as required for application as a pump source. Narrow linewidth operation is sustained to 100degC, enabled by use of a grating with a high coupling coefficient.     

Optical and structural characteristics of Ga-doped ZnO films

The n-ZnO films doped with Ga to the content 2.5 at % are produced by pulse laser deposition onto the (0001) oriented single crystal sapphire substrates. The transmittance spectra of the ZnO films in the range from 200 to 3200 nm are studied in relation to the Ga dopant content. It is established that an increase in the Ga content shifts the fundamental absorption edge to the blue region, but reduces the transparency of the ZnO films in the infrared spectral region. The dependence of the band gap on the level of doping with Ga is determined. The photoluminescence spectra of the ZnO films doped to different levels are recorded. It is established that the PL intensity and peak position vary unsteadily with the level of doping. X-ray diffraction studies of the structure of the films are carried out. It is found that the crystallographic parameters (the lattice constant c) of the ZnO film depend on the Ga dopant content and the conditions of deposition of the films.