A discharge heated copper vapor laser

A simple, reliable copper vapor laser is described with vapor produced by discharge heating. Average output power of 1.3 W has resulted at 6.8 kHz and a specific energy of 39 μJ/cm³. Copper vapor density as high as3 times 10^{16}cm^-3was achieved.     

Zur Kenntnis des Kaffee-Aromas und seiner Ver?nderungen im Laufe der Lagerung von R?stkaffee

Zusammenfassung Zum Studium der Aromabestandteile aus frischem und gelagertem Röstkaffee werden von den drei Fraktionen verschiedener Siedebereiche die Verbindungen mittlerer Flüchtigkeit näher untersucht. Es handelt sich um ein. Vielkomponentengemisch (Sdp 100 bis etwa 220° C), das durch Trägerdampfdestillation unter vermindertem Druck gewonnen wird.Während die leichtflüchtigen Verbindungen (0–100° C) lediglich die Aromaspitze bedingen, erweisen sich die mittel- bis schwerflüchtigen Substanzen als die Träger des typischen Kaffee-Aromas, zu dem die Carbonyle zusammen mit den Phenolen mehr beitragen als das häufig für überaus bedeutsam gehaltene Furfurylmercaptan. Die Ergebnisse der chemischen Aufarbeitung lassen eindeutig erkennen, daß das volle Aroma des Kaffees nicht auf der Anwesenheit einzelner markanter Komponenten beruht, sondern durch Mischung einer Vielzahl von Verbindungen verschiedener Konstitution, Konzentration und Flüchtigkeit zustande kommt. Nur zusammen ergeben sie diese Wirkung, indem sich ihre Duft- und Geschmacksnuancen addieren, überlagern und gegenseitig abrunden. Hierbei sind vier Verbindungsklassen, nämlich Monocarbonsäuren, Stickstoffbasen, Phenole und neutrale Verbindungen, in erster Linie Vertreter der Carbonylreihe, von besonderer Bedeutung.Bei der Analyse der Aromakondensategelagerten Kaffees kann innerhalb der gaschromatographisch nachweisbaren Verbindungen bis etwa 170° C keine zusätzliche, möglicherweise den Altgeschmack verursachende Komponente nachgewiesen werden. Die Untersuchungsergebnisse deuten vielmehr darauf hin, daß man ebensowenig wie beim Frischaroma für den Altgeschmack eine eng begrenzte Anzahl von Verbindungen verantwortlich machen kann.I. Mitteilung: Diese Z.119, 293 (1963). Beide Mitteilungen sind Auszüge aus der Dissertation vonRosemarie Radtke, Universität München 1964.     

Zur Berechnung hydrodynamischer Lager mit Hilfe von Tschebyscheff-Polynomen

Forschung im Ingenieurwesen - Auf der Basis des Ritz-Galerkinschen Verfahrens wird eine analytische Näherungsmethode zur Lösung der Reynoldsschen Differentialgleichung angegeben. Die...     

A dimeric crystal structure for the N-terminal two domains of intercellular adhesion molecule-1

The 3.0-A structure of a 190-residue fragment of intercellular adhesion molecule-1 (ICAM-1, CD54) reveals two tandem Ig-superfamily (IgSF) domains. Each of two independent molecules dimerizes identically with a symmetry-related molecule over a hydrophobic interface on the BED sheet of domain 1, in agreement with dimerization of ICAM-1 on the cell surface. The residues that bind to the integrin LFA-1 are well oriented for bivalent binding in the dimer, with the critical Glu-34 residues pointing away from each other on the periphery. Residues that bind to rhinovirus are in the flexible BC and FG loops at the tip of domain 1, and these and the upper half of domain 1 are well exposed in the dimer for docking to virus. By contrast, a residue important for binding to Plasmodium falciparum-infected erythrocytes is in the dimer interface. The presence of A' strands in both domains 1 and 2, conserved hydrogen bonds at domain junctions, and elaborate hydrogen bond networks around the key integrin binding residues in domain 1 make these domains suited to resist tensile forces during adhesive interactions. A subdivision of the intermediate (I) set of IgSF domains is proposed in which domain 1 of ICAM-1 and previously described I set domains belong to the I1 set and domain 2 of ICAM-1, ICAM-2, and vascular cell adhesion molecule-1 belong to the I2 set.     

Metal oxide gas sensor for high temperature application

 The present study is focused on the development of a gas sensor for application in a high temperature environment. The sensor has been realised using thin films prepared on silicon substrates including a high temperature stable heating and wiring system. TiO₂ acts as sensitive layer. Measurements have been carried out in synthetic gas mixtures as well as in gases in a given application. Neural networks and multivariate data analysis have been used for determining the gas concentrations. The capability to detect CO, NO _x , and toluene is shown. Received: 3 February 2000/Accepted: 3 February 2000     

Contrasting responses to multiple chemotactic stimuli in transendothelial migration: heterologous desensitization in neutrophils and augmentation of migration in eosinophils

At inflammatory sites in vivo, leukocytes may confront multiple, competing chemoattractive signals. We found significant differences between eosinophils and neutrophils in transendothelial chemotaxis to a chemoattractant diffusing from the lower chamber, when a chemoattractant that binds to another receptor is present at uniform concentration. The transendothelial migration of eosinophils to FMLP, C5a, RANTES, or MCP-3 was totally inhibited by the presence of the homologous chemoattractant, and only RANTES and MCP-3 showed mutual inhibition. C5a and to a lesser extent FMLP chemokinetically stimulated migration to RANTES and MCP-3, without stimulating random migration. Results with neutrophils contrasted. The presence of FMLP not only abrogated neutrophil transmigration to FMLP but also strongly decreased chemotaxis to C5a, IL-8, and Gro-alpha. Similarly, C5a inhibited neutrophil chemotaxis to IL-8 and Gro-alpha. IL-8 almost totally abrogated chemotaxis to Gro-alpha, but Gro-alpha only moderately inhibited chemotaxis to IL-8. Neither IL-8 nor Gro-alpha significantly inhibited transmigration to FMLP or C5a. Actin polymerization in eosinophils and neutrophils was desensitized by the same combinations of chemoattractants that desensitized chemotaxis. We conclude that eosinophils have at least three noninterfering receptor-signal transduction pathways for chemotaxis and actin polymerization. In contrast, the signaling pathways for FMLP, C5a, and IL-8/Gro-alpha in neutrophils are heterologously cross-desensitized, with a hierarchy of resistance to competing signals of FMLP > C5a > IL-8 > Gro-alpha, in agreement with previous results in neutrophils on the Ca2+-mobilizing response. These results may have important implications for the behavior of these cell types in inflammatory sites.     

Development of a low-cost 35 GHz radar sensor

Two different 35 GHz low-cost rf front-end Doppler units suited for automotive applications have been constructed. The homodyne unit consists of both receiving and transmitting corporate-fed microstrip patch array antennas, a microstrip directional coupler, a monolithic GaAs fected oscillator and an integrated single Schottky diode mixer. The autodyne configuration uses only one antenna and the fected as a self-oscillating mixer. Inexpensive microstrip technology has been used which yields a good compromise between cost factor and technical performance.     

Ligand binding to heme proteins: III. FTIR studies of His-E7 and Val-E11 mutants of carbonmonoxymyoglobin

Fouier-transform infrared (FTIR) difference spectra of several His-E7 and Val-E11 mutants of sperm whale carbonmonoxymyoglobin were obtained by photodissociation at cryogenic temperatures. The IR absorption of the CO ligand shows characteristic features for each of the mutants, both in the ligand-bound (A) state and in the photodissociated (B) state. For most of the mutants, a single A substate band is observed, which points to the crucial role of the His-E7 residue in determining the A substrate spectrum of the bound CO in the native structure. The fact that some of the mutants show more than one stretch band of the bound CO indicates that the appearance of multiple A substates is not exclusively connected to the presence of His-E7. In all but one mutant, multiple stretch bands of the CO in the photodissociated state are observed; these B substates are thought to arise from discrete positions and/or orientations of the photodissociated ligand in the heme pocket. The red shifts of the B bands with respect to the free-gas frequency indicate weak binding in the heme pocket. The observation of similar red shifts in microperoxidase (MP-8), where there is no residue on the distal side, suggests that the photodissociated ligand is still associated with the heme iron. Photoselection experiments were performed to determine the orientation of the bound ligand with respect to the heme normal by photolyzing small fractions of the sample with linearly polarized light at 540 nm. The resulting linear dichroism in the CO stretch spectrum yielded angles alpha > 20 degrees between the CO molecular axis and the heme normal for all of the mutants. We conclude that the off-axis position of the CO ligand in the native structure does not arise from steric constraints imposed by the distal histidine. There is no clear correlation between the size of the distal residue and the alpha of the CO ligand.