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  • 1
    Electronic Resource
    Electronic Resource
    Enhanced supercurrent density in polycrystalline YBa 2 Cu 3 O 7-δ at 77 K from calcium doping of grain boundaries (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 407 (2000), S. 162-164 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] With the discovery of high-temperature superconductivity, it seemed that the vision of superconducting power cables operating at the boiling point of liquid nitrogen (77 K) was close to realization. But it was soon found that the critical current density Jc of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35025014
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  • 2
    Electronic Resource
    Electronic Resource
    Design and realization of an all d-wave dc π-superconducting quantum interference device (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 912-914 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The predominantly dx2−y2-pairing symmetry in most high-Tc superconductors provides the opportunity to fabricate Josephson junction circuits in which part of the junctions are biased by a phase difference of the superconducting order parameter of π. We present fabrication and measurements of an all high-Tc dc superconducting quantum interference device (dc SQUID) realized with thin-film technology, of which the Josephson junctions consist of one standard junction and one junction with a π-phase shift. The characteristics of the π-SQUID are compared with the properties of a standard high-Tc SQUID. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125627
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  • 3
    Electronic Resource
    Electronic Resource
    T cell reactivity in neonates from an East and a West German city – results of the LISA study (2002)
    Oxford, UK : Blackwell Science, Ltd
    Allergy 57 (2002), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Within an ongoing birth cohort study (LISA) the cytokine production of cord blood T cells was compared between neonates from Leipzig (East Germany) and Munich (West Germany). The aim of this study was to analyse regional differences and influencing factors of the immune status. Methods: Cytokine production was measured in a randomly selected subgroup of 158 children from the LISA (Life style – Immune system – Allergy) cohort by intracellular cytokine staining. Information on family “atopy” history (FAH) and home characteristics was obtained from questionnaires. Results: Reduced numbers of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) producing T cells were found in association with biparental FAH and housing renovation during pregnancy. In addition, cytokine production was influenced by season. In Munich, the frequency of biparental FAH and of renovation measures during pregnancy was significantly higher as compared to Leipzig. Neonates from Munich showed significantly decreased amounts of IFN-γ and TNF-α and elevated levels of interleukin-4 (IL-4) producing T cells. Differences in cytokine production between Munich and Leipzig were influenced by season (IL-4) and housing renovation (IFN-γ, TNF-α). Conclusions: Since differences in the T cell cytokine production of neonates in Munich and Leipzig are independent from FAH our findings may provide evidence for the impact of environmental factors upon the fetal immune system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0105-4538.2002.00001.x
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  • 4
    Electronic Resource
    Electronic Resource
    Detection and Localization of Two Constitutive NOS Isoforms in Bull Spermatozoa (2003)
    Berlin, Germany : Blackwell Verlag GmbH
    Anatomia, histologia, embryologia 32 (2003), S. 0 
    Details
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Bull spermatozoa were examined for the presence and localization of constitutive Nitric Oxide Synthase (NOS), as nitric oxide (NO) is involved in calcium-dependent capacitation. In bull spermatozoa, NO generation is enhanced by l-arginine (3 μm) and abolished by the NOS-inhibitor N-nitro-l-arginine methyl ester (l-NAME). In addition, presence of NOS in bull spermatozoa was verified by immunohistochemistry, revealing the existence of both neuronal NOS (nNOS) and endothelial NOS (eNOS) immunoreaction. These findings were confirmed by Western blot technique, showing immunoreactive bands at 161 kDa (nNOS) and 133 kDa (eNOS). Confocal laser microscopy localized nNOS related immunofluorescence at the acrosome cap of sperms and their flagellum-mainpart. This technique also identified eNOS staining spread over the spermatozoan head. In conclusion, immunohistochemistry, Western blot technique, and NO generation suggest the presence of n- and eNOS in bull spermatozoa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0264.2003.00459.x
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  • 5
    Electronic Resource
    Electronic Resource
    Assessment of tissue damaging effects of mixed micellar absorption enhancers on the intestinal mucosa of common carp (Cyprinus carpio), African catfish (Clarias gariepinus) and rainbow trout (Oncorhynchus mykiss) as a consequence of enhanced intestinal absorption of sGnRH-a (2001)
    Oxford UK : Blackwell Science Ltd.
    Journal of applied ichthyology 17 (2001), S. 0 
    Details
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Non-ionic surfactant–polyoxyethylene sorbitan monooleate (Tween-80) and oleic acid are food and pharmaceutical ingredients for oral and parenteral delivery and generally regarded as safe (GRAS). They have the potential as an intestinal absorption enhancer for the development of oral drug delivery systems. However, their safety in terms of mucosal integrity has yet to be evaluated. Therefore, the purpose of the present work was to study the tissue damaging effects of Tween-80, oleic acid and of their mixed micellar formulation (oleic acid + Tween-80). This was investigated at 2 h and 24 h after rectal delivery and compared with the topical effect of polyoxyethylene 9 lauryl ether (Polydocanol). The same experiment was carried out on three species with distinct feeding habits: the common carp, Cyprinus carpio (L.); the African catfish, Clarias gariepinus (Burchell); and the rainbow trout, Oncorhynchus mykiss (Walb.). Based on the findings of this study it was concluded that Tween-80 (4%), or its mixed micelle with oleic acid (0.6%) can be considered as a safe formulation, inducing only a moderate alteration of the intestinal mucosa, comparable to the effect of an isotonic saline. By contrast, in the three species, the same dose of Polydocanol, or of its mixed micelle with oleic acid, induced severe tissue damage of the intestinal mucosa, still present after 24 h. Mixed micelles of oleic acid with Tween-80 were also demonstrated as increasing the intestinal absorption of the salmon gonadotropin releasing hormone analogue (sGnRH-a) in catfish, C. gariepinus, and consequently stimulating GtH II secretion. This effect was compared with the action of other drugs considered as intestinal absorption enhancers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0426.2001.00303.x
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  • 6
    Electronic Resource
    Electronic Resource
    Myocardial hibernation – adaptation to ischemia (2000)
    Springer
    Zeitschrift für Kardiologie 89 (2000), S. 101-108 
    Details
    ISSN: 1435-1285
    Keywords: Key words Ischemia – reperfusion – hibernation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The concept of myocardial hibernation implies a downregulation of contractile function as an adaptation to a reduction in myocardial blood flow that serves to maintain myocardial integrity and viability during persistent ischemia. Unequivocal evidence for this concept exists in scenarios of myocardial ischemia that last for several hours; the recovery of energy and substrate metabolism, the potential for recruitment of inotropic reserve at the expense of metabolic recovery, and lack of necrosis are established criteria of short-term hibernation. Furthermore, experimental studies have demonstrated regional myocardial dysfunction at reduced resting blood flow that recovered upon reperfusion, which is consistent with chronic hibernation. In patients, the importance of reduced baseline blood flow vs. that of superimposed reetitive stunning is somewhat controversial; however, in most studies blood flow is reduced, and the myocardium must be ischemic often enough to have persistent dysfunction. Morphologically, hibernating myocardium displays features of dedifferentiation with loss of cardiomyocytes and myofibrils and of degeneration with increased interstitial fibrosis. The mechanisms of short-term hibernation, apart from reduced calcium responsiveness, are not clear at present. With the identification of the underlying mechanism(s) of hibernation, it can potentially be recruited and reinforced pharmacologically to delay impending myocardial infarction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 7
    Electronic Resource
    Electronic Resource
    Neuromuskuläre Reinnervation mimischer Muskulatur Eine histomorphologische Untersuchung am M. zygomaticus des Kaninchens (2000)
    Springer
    HNO 48 (2000), S. 598-605 
    Details
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Nerven-Muskel-Transplantation ; Fasertypgruppierungen ; Reinnervation ; Keywords Facial reinnervation ; Nerve-muscle transplantation ; Facial palsy ; Muscle fibre types
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract To evaluate occurrences of reinnervation and degeneration, the portio auricularis of the zygomatic muscle was reinnervated (either primary or secondary reinnervation) with an interval of 6 weeks, using a neuromuscular transplant of the sternohyoid muscle, which was left at the ansa hypoglossi. Histological examination was performed 6 and 12 weeks later. Enzymatic stains for myofibrillar ATPase were used for differentiation of muscle fibre types. Histomorphological features of denervation and reinnervation were analysed. Six weeks after denervation and primary neuromuscular transplantation, type grouping in regions close to the transplanted muscle were detectable as signs of reinnervation. After a period of 12 weeks, the progressing reinnervation was proved by type grouping in distal areas of the muscle far from the area of transplantation. At the same time, differentiation of fibre typing in the type grouping areas increased. All denervated and reinnervated muscles had pathological variations of fibre diameter. Primary reinnervated muscles showed tendency of normalization in variation of diameter. Compared with primary reinnervated muscles, secondary reinnervated muscles with an interval of 6 weeks showed pronounced polymorphology of fibres and a high pathological increase of the variation of fibre diameters. The interfascicular space was significantly spread. The tendency of reinnervation with incidence of fibre type grouping was comparable to primary reinnervated muscles and also occurred 6 weeks after transplantation.
    Notes: Zusammenfassung Zur Beurteilung der Reinnervations- und Degenerationsprozesse der mimischen Muskulatur wurde am Kaninchen die denervierte Portio auricularis des M. zygomaticus sowohl primär als auch sekundär mit einem neuromuskulären Transplantat aus dem M. sternohyoideus mit der innervierenden Ansa hypoglossi reinnerviert und 6 bzw. 12 Wochen danach histologisch untersucht. Anhand der ATPase-Reaktion wurde eine Differenzierung der Muskelfasertypen vorgenommen und histomorphologische Merkmale der Denervation und Reinnervation ausgewertet. 6 Wochen nach Denervation und primärer neuromuskulärer Transplantation waren Fasertypgruppierungen als Reinnervationszeichen in Transplantatnähe nachweisbar. Nach einer Reinnervationsphase von 12 Wochen konnte das Fortschreiten eines Reinnervationsvorgangs anhand von Fasertypgruppierungen in transplantatfernen Muskelarealen nachgewiesen werden. Gleichzeitig stellte sich eine zunehmende Differenzierung der Fasertypen in den Gruppierungen dar. In allen denervierten und reinnervierten Gruppen waren pathologische Kalibervariationen der Muskelfaser nachweisbar. Primär reinnervierte Muskeln zeigten im Laufe einer Reinnervationsphase von 12 Wochen eine Normalisierungstendenz der Kalibervariationen. Sekundär, im Intervall von 6 Wochen nach Denervation transplantierte Muskeln, zeigten im Vergleich zu primär transplantierten Muskeln eine ausgeprägtere Faserpolymorphie mit einer hochgradig pathologisch erhöhten Kalibervariation. Der interfaszikuläre Raum war deutlich verbreitert. Die Reinnervationstendenz mit Nachweis von Fasertypgruppierungen war vergleichbar zu primär transplantierten Muskeln und war ebenfalls bereits 6 Wochen nach Transplantation nachweisbar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001060050622
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of oxygen and titanium contents on the stability of nanocrystalline Ti–Ru–Fe–O cathode materials for chlorate electrolysis (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 491-498 
    Details
    ISSN: 1572-8838
    Keywords: ball milling ; chlorate electrolysis ; electrocatalysis ; hydrogen evolution ; nanocrystalline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodes made from nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2), with y varying from 0 to 1 by step of 0.25, and Ti:Ru:Fe:O (2:1:1:w), with w varying from 0 to 2 by step of 0.5, were prepared and tested as activated cathodes for the hydrogen evolution reaction in typical chlorate electrolysis conditions. These electrodes were subjected to an accelerated aging test, consisting of a succession of cycles of hydrogen discharge (HER) and open-circuit (OCP) conditions. In addition to monitoring the cathodic overpotential value during the aging test, visual inspection and mass loss measurements were performed on the electrodes at the end of the test to assess their stability. In the case of Ti:Ru:Fe (2:1:1), a large increase of the cathodic overpotential value is observed after 20 cycles. Adding O to the formulation causes a remarkable improvement of the long-term stability of the electrodes. As little as [O] = 10 at.% in nanocrystalline Ti:Ru:Fe:O (2:1:1:w) materials is sufficient for the electrode to show absolutely no sign of degradation after 50 cycles of HER/OCP, the longest accelerated test conducted. Adding more O to the formulation of the material does not lead to further stability improvement. A better stability under the conditions of the accelerated aging test can also be observed for nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2) materials with y 〉 0. In that case however, the level of improvement is dependent on the value of y. The best results are obtained for y = 0.75. A hypothesis is proposed to explain the improved stability obtained by lowering the Ti content and/or by adding O. The similarity and difference between both ways of improving the stability of the nanocrystalline Ti:Ru:Fe materials are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003961417762
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  • 9
    Electronic Resource
    Electronic Resource
    Improvement of the high energy ball-milling preparation procedure of CO tolerant Pt and Ru containing catalysts for polymer electrolyte fuel cells (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 1243-1253 
    Details
    ISSN: 1572-8838
    Keywords: mechanical alloying ; PEFC ; PEM fuel cell ; process control agent ; Pt–Ru alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ball-milling has been used to prepare performing CO tolerant polymer electrolyte fuel cell anode catalysts that contain Pt and Ru. The catalyst precursors are obtained by milling together Pt, Ru and a dispersing agent in the atomic ratio 0.5, 0.5 and 4.0. This precursor is not easily recovered after milling because it sticks to the walls of the vial and on the grinding balls. However, the precursor is recovered as a powder when a process control agent (PCA) is added during the milling step. Various PCAs have been used. The PCA should not interfere with the electrocatalytic activity of the catalysts obtained by leaching the precursor. The best preparation of catalyst precursors are obtained by milling: (i) Pt, Ru and Al (dispersing agent) in the atomic ratio 0.5, 0.5, 4.0 + 10 wt% NaF (PCA) or (ii) Pt , Ru and MgH2 in the 0.5, 0.5, 4.0 atomic or molecular ratio. In this case, MgH2 plays at the same time the role of a dispersing agent and that of a PCA. The catalysts are obtained by leaching Al and NaF in (i) or MgH2 in (ii). The CO tolerance of these catalysts is equivalent to that of Pt0.5Ru0.5 Black from Johnson Matthey. The ball-milled catalysts have a surface area comprised between 30 and 44 m2 g−1. As-prepared catalysts are mainly made of metallic Pt and metallic plus oxidized Ru. After fuel cell tests, Pt is completely metallic while the oxidized Ru content decreases but does not disappear. These catalysts are composed of particles with crystallites of two different sizes: in (i) nanocrystallites (∼4 nm) that contain essentially Pt alloyed with Al and perhaps some Ru, and larger (≥∼30 nm) crystallites that contain essentially Ru; in (ii) Pt nanocrystalline particles that may contain some Ru and larger particles that contain essentially either Ru or Pt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026542821607
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  • 10
    Electronic Resource
    Electronic Resource
    Cathodes for chlorate electrolysis with nanocrystalline Ti–Ru–Fe–O catalyst (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 1061-1067 
    Details
    ISSN: 1572-8838
    Keywords: chlorate electrolysis ; high activity ; hydrogen cathodes ; nanocrystalline Ti–Ru–Fe–O catalyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Cathodes for chlorate electrolysis were prepared by mixing nanocrystalline Ti–Ru–Fe–O catalyst powder with small amounts of Teflon and subsequent hot pressing on a carbon–Teflon sublayer. Initially, the electrode materials were characterized by SEM, EDX, XRD and BET measurements. The behaviour of electrodes with catalyst loadings from 300 mg cm−2 reduced to 10 mg cm−2 was investigated in chlorate electrolyte with pH 6.5 and in part, for comparison, in 1 M sodium hydroxide solution at 70 ∘C. Several methods have been used: cyclic voltammetry for the determination of double layer capacitance, Tafel plot analysis, cathodic potentiodynamic polarization and potentiostatic tests at i = −250 mA cm−2. The as-milled catalyst powder electrodes showed a high activity for the HER in chlorate electrolyte particularly expressed in low overpotentials of about 580 mV at −250 mA cm−2 for catalyst loadings down to 20 mg cm−2 and high double layer capacitances in the freshly prepared state. These electrodes show increased activity at low polarization. The long-term stability during electrolysis was also analysed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004030706423
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