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  • Articles: DFG German National Licenses  (57)
  • 2000-2004  (13)
  • 1990-1994  (44)
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  • Articles: DFG German National Licenses  (57)
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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 375-380 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Elastic recoil detection and Rutherford backscattering were adapted to a stoichiometric study of thin Ta2O5 films deposited on Si substrates by means of the reactive sputtering (SP) and chemical-vapor-deposition (CVD) method. Before annealing the samples it was observed that (i) the atomic ratio of oxygen to tantalum in the SP films agreed with 5/2 within the experimental accuracy and (ii) the CVD films have less oxygen content than the other samples. The specimens were annealed for 30 min under the following three conditions: (a) in dry oxygen ambient at 800 °C; (b) in ozone atmosphere under ultraviolet irradiation (UV ozone) at 300 °C; and (c) two-step treatment of (a) after the (b) process. Each oxidizing process has shown a certain positive effect on the thin CVD samples. Among them, the two-step treatment has proven to be very effective to restore the stoichiometry of 5/2 in the CVD films. Additionally the thickness of contaminant carbon films on the surface of the samples has been reduced by annealing in the oxidizing atmosphere. The relationship between the chemical composition and the electric properties of the samples is discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6428-6433 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The estimation for the water vapor included in chemically generated excited oxygen flow and the influence of the water vapor on the excited oxygen species are presented. The concentration of the water vapor in the flow was changed by altering the temperatures of the solution and the cold trap and then, it was estimated by measuring the the pressure change and by measuring the concentration of the excited oxygen molecules. The fraction of O2(1Δ) to the total oxygen did not change with the water vapor pressure, but the concentration of O2(1Σ) changed significantly. Applying the high sensitivity of O2(1Σ) concentration to H2O, the estimation of a small quantity of water vapor concentration was available in the system.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 79-83 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A high-power chemical oxygen iodine laser system has been developed with industrial applications in mind. The present system shows fairly high efficiency, good stability, and reasonably good beam quality applicable to practical applications. Highly efficient power transmission through optical fibers has been demonstrated.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2548-2552 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Limiting molar conductances of the K+ and Cl− ions in heavy and light water have been determined at 45 °C as a function of pressure up to 2000 kgf cm−2 (1 kgf cm−2 =0.9807×105 Pa) from the measured conductances and transference numbers of KCl. The residual friction coefficients (Δζobs ) of the K+ and Cl− ions obtained by using their limiting molar conductances and the bulk viscosity of solvent are compared up to 1000 kgf cm−2 with the corresponding values (ΔζHO ) predicted by the Hubbard–Onsager dielectric friction theory. As predicted, Δζobs for the cation in H2 O is smaller than that in D2 O and slightly decreases with increasing pressure, while its value in D2 O is almost invariant in the pressure range studied. The failure of the continuum theory in D2 O indicates that the effect of the open structure of water on the cation migration cannot be neglected even at 45 °C because of stronger hydrogen bonds in D2 O than in H2 O. For the anion, on the other hand, the continuum theory shows more serious limitations: (i) Δζobs (Cl−) in H2 O is not smaller than that in D2 O even at 45 °C with a large difference at high pressures and (ii) Δζobs (Cl−) becomes negative in both types of water at high pressures. The difference in Δζ(Cl−) between theory and experiment at 45 °C, however, becomes much smaller than that at lower temperatures.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 645-646 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Near-infrared emission has been observed in a chemically generated singlet oxygen system. Spectrum peaks observed at 1090, 1275, and 1550 nm appear to correspond to O2(1Δ)O2(3Σ) dimer transitions to ground state accompanied by vibrational changes. The experimental result suggests that the previously observed visible emission which accompanies the present infrared emission is also due to an excited oxygen dimer. The possibility of lasing at the infrared wavelengths is discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3102-3107 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The laser-prearc railgun, that utilizes the phenomenon of laser-induced arc formation, was constructed and tested with plastic pellet projectiles. We envision our railgun as especially well suited as a solid hydrogen pellet injector for magnetic confinement fusion. The system consisted of a gas gun for preacceleration of a pellet and a railgun for its primary acceleration. A Q-switched ruby laser was used to induce electrical breakdown of propellant helium gas behind a dielectric pellet in the railgun. The present railgun was shown to accelerate a plastic pellet up to a velocity of 2.4 km/s.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 12144-12146 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Influenza virus (IV) infection causes airway inflammation; however, it has not been determined whether IV infection could catabolize arachidonic acid cascade in airway epithelial cells. In addition, the responsible intracellular signalling molecules that catabolize arachidonic acid cascade have not been determined.Objective In the present study, to clarify these issues, we examined the cyclooxygenase (COX) expression, cytosolic phospholipase A2 (cPLA2) phosphorylation and prostaglandin E2 (PGE2) release in human bronchial epithelial cells (BEC) upon IV infection, and the role of mitogen-activated protein kinase (MAPK) including extracellular signal-regulated kinase (ERK), p38 MAPK and c-Jun-NH2-terminal kinase (JNK) in catabolizing arachidonic acid cascade in BEC.Methods COX-2 expression, phosphorylation of cPLA2 and phosphorylation of ERK, JNK and p38 MAPK were determined by Western blot. The concentrations of PGE2 were determined by ELISA. PD 98059 as a specific inhibitor of MAPK kinase-1 (MEK-1), an up-stream kinase of ERK, SB 203580 as a specific inhibitor of p38 MAPK and CEP-11004 as a specific inhibitor of JNK cascade were used to investigate the role of ERK, p38 MAPK and JNK in catabolizing arachidonic acid cascade in BEC.Results The results showed that (1) IV infection increases COX-2 expression, cPLA2 phosphorylation and PGE2 release, (2) ERK, p38 MAPK and JNK were phosphorylated, (3) CEP-11004 and PD 98059 predominantly attenuated COX-2 expression and cPLA2 phosphorylation, respectively, (4) SB 203580 did not remarkably affect COX-2 expression and cPLA2 phosphorylation, and (5) each inhibitor dose-dependently attenuated PGE2 release by various extents.Conclusion These results indicate that IV infection activates three distinct MAPKs, ERK, p38 MAPK and JNK, to participate to various extents in the induction of PGE2 synthesis from arachidonic acid in BEC.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Previous studies have shown that rat peritoneal mast cells and mast cell model rat basophilic leukaemia (RBL-2H3) cells generate intracellular reactive oxygen species (ROS) in response to antigen challenge. However, the physiological significance of the burst of ROS is poorly understood.Objective The present study was undertaken to investigate the role of superoxide anion in mediator release in rat and human cell systems.Methods RBL-2H3 cells were directly stimulated with anti-rat FcεRI α-subunit monoclonal antibody (mAb). For the analysis of human cell system, leucocytes were isolated by dextran sedimentation from healthy volunteers or from patients, and challenged either with anti-human FcεRI mAb or with the relevant antigens. Superoxide generation was determined by chemiluminescence-based methods. The releases of histamine and leukotrienes (LT)s were determined by enzyme-linked immunosorben assay (ELISA).Results Cross-linking of FcεRI on RBL-2H3 cells or on human leucocytes from healthy donors by the anti-FcεRI mAb resulted in a rapid generation of superoxide anion, as determined by chemiluminescence using superoxide-specific probes. Similarly, leucocytes from patients generated superoxide anion in response to the challenge with the relevant allergen but not with the irrelevant allergen. Furthermore, diphenyleneiodonium (DPI), a well-known inhibitor of flavoenzymes suppressed the superoxide generation and the release of histamine and LTC4 induced by the anti-FcεRI mAb or by allergen in parallel.Conclusion These results indicate that both RBL-2H3 cells and human basophils generate superoxide anion upon FcεRI cross-linking either by antibody or by allergen challenge and that blockade of the generation prevents the release of allergic mediators. The findings strongly support the role of superoxide generation in the activation of mast cells and basophils under both physiological and pathological conditions. The findings suggest that drugs regulating the superoxide generation have potential therapeutic use for allergic disorders.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 58 (2001), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The onset of schooling behaviour and brain growth in larval yellowtail Seriola quinqueradiata larvae fed on Artemia enriched with oleic acid (OA), eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) for 10 days was investigated. Larvae from the DHA groups schooled with parallel orientation while those of the EPA groups showed only aggregation. Larvae of the OA groups were dispersed. DHA and EPA groups showed significantly smaller nearest neighbour distance compared with OA groups, and DHA groups showed significantly smaller values of nearest neighbour angle compared with the other groups. The relative volume of the tectum opticus (TO) of the DHA group was significantly larger in two experiments and also the relative volume of the cerebellum (CE) of that group was significantly larger in one experiment. Dietary DHA is probably critically important for the development of the brain, particularly TO, during the larval stages, and that development of TO may be the key factor of the ontogeny of schooling behaviour.
    Type of Medium: Electronic Resource
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