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  • 1
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Sevofluran ; Enfluran ; Fluorid ; Nierenfunktion ; Key words Sevoflurane ; Enflurane ; Fluoride ; Renal function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Sevoflurane is a “new” volatile inhaled anaesthetic. Owing to its lower blood-gas solubility coefficient, emergence from anaesthesia is faster with sevoflurane than with isoflurane, enflurane, or halothane. Sevoflurane undergoes metabolic biodegradation, releasing inorganic fluoride ions that could produce nephrotoxicity. In this study, we compared serum inorganic fluoride concentrations (IFCs) in patients receiving either sevoflurane or enflurane. Furthermore, indices of renal function were evaluated until the 3rd postoperative day. Methods. Thirty patients with no history of renal or hepatic disease and with an anticipated duration of anaesthesia of at least 3 h were studied in an open, prospective, randomised clinical trial. Anaesthesia was induced with fentanyl, thiopentone, and vecuronium for facilitating endotracheal intubation. Anaesthesia was maintained with sevoflurane or enflurane, 60% nitrous oxide in oxygen, and additional doses of fentanyl. Blood samples for serum IFCs were obtained preoperatively and 2 and, if possible, 4 and 6 h after starting sevoflurane or enflurane, at the end of anaesthesia, and 1, 2, 4, 8, 12, 24, 48 and 72 h post-anaesthesia. Fluoride analysis was performed using an ion-selective electrode. Indices of renal function (serum sodium, osmolality, creatinine, urea, and uric acid, urine specific gravity, osmolality, and pH) were evaluated preoperatively, at the end of anaesthesia, and 24, 48, and 72 h post-anaesthesia. Results. The duration of anaesthetic exposure was approximately 1.65 MAC-h for both inhaled anaesthetics. Peak serum IFCs were higher with sevoflurane (34.5 μmol/l) than with enflurane (19.4 μmol/l). Fluoride levels decreased more rapidly with sevoflurane: 24 h post-anaesthesia there was no difference between sevoflurane and enflurane (Fig. 1). The area under the curve (AUC) was greater with sevoflurane (688 μmol/l·h) than with enflurane (591 μmol/l·h). For both groups correlation coefficients were higher for MAC-h and AUC than for MAC-h and peak serum IFC (Figs. 2 and 3). Indices of renal function did not change in either group. Discussion. In our study 1.69 MAC-h sevoflurane produced peak serum IFCs of 34.5 μmol/l. This is in accordance with the investigation of Frink et al. [4], who reported approximately 30 μmol/l after 1.4 MAC-h sevoflurane. Peak serum IFCs with sevoflurane were twice those with enflurane. Within the first 24 h post-anaesthesia, fluoride levels decreased more rapidly after sevoflurane. AUC may be more important than peak serum IFC in evaluating patients who are at risk for renal concentrating defects. In our study there was no evidence of renal dysfunction in either group.
    Notes: Zusammenfassung In einer offenen, randomisierten, prospektiven und vergleichenden Studie zwischen Sevofluran und Enfluran wurden bei 30 nierengesunden Patienten die Serumfluoridkonzentrationen und die exokrine Nierenfunktion bis zum 3. postoperativen Tag untersucht. Die applizierte Dosis betrug in beiden Gruppen ca. 1,65 MAC-Stunden. Die maximale Serumfluoridkonzentration war mit 34,5 μmol/l nach Sevofluran fast doppelt so hoch wie nach Enfluran (19,4 μmol/l). 24 h nach Anästhesieende war die Serumfluoridkonzentration in der Sevoflurangruppe auf ca. 25% des Maximalwerts abgefallen, in der Enflurangruppe auf ca. 40% des Maximalwerts. Ab diesem Zeitpunkt war kein Unterschied mehr zwischen den beiden Gruppen nachweisbar. Die Fluoridbelastung (Area under the curve, AUC) war nach Sevofluran (688 μmol/l·h) etwas größer als nach Enfluran (591 μmol/l·h). Die Korrelation von MAC-Stunden (applizierte Dosis) und AUC war in beiden Gruppen besser als die von MAC-Stunden und maximaler Serumfluoridkonzentration. Veränderungen von Laborvariablen (Natrium, Osmolalität, Kreatinin, Harnstoff und Harnsäure i.S., spez. Gewicht, Osmolalität und pH-Wert i.U.), die auf eine Nierenschädigung hinweisen würden, wurden nicht nachgewiesen.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 235-240 (1994), S. 1291-1292 
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 235-240 (1994), S. 1093-1094 
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 232 (1994), S. 82-88 
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4007-4018 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: WO3 films, either prepared by sputtering or evaporation under high or ultrahigh vacuum conditions, were irradiated with He+ and Ar+ ions (energy range 300–350 keV) at ambient and low temperatures (77–100 K). The resulting ion induced changes of the optical absorption as well as of the electrical conductivity could be determined on one and the same sample, which enables the variable range hopping (VRH) model to be tested under the assumption that the density of irradiation induced color centers is proportional to the electronic density of states contributing to the hopping conductivity. It is found that the data obtained at 300 K for He+ and Ar+ bombardment can be described within the VRH model by one common conductivity versus absorption curve, even though the effectiveness per projectile of the heavier ion for coloration as well as for increasing the conductivity is much higher. This is different at low temperatures. While the ion induced coloration is practically independent of the irradiation temperature for both projectiles, the effectiveness per projectile to enhance the conductivity is interchanged. This is attributed to the additional damage produced by the heavier ion at low temperatures resulting in strongly impeded hopping processes. Consistent with the VRH model, the temperature dependence of the conductivity of ion bombarded WO3 films follow the Mott "T−1/4" law, if the ion induced conductivity is not too high. For very high ion fluences clear deviations from the VRH model are observed for the conductivity versus absorption curves accompanied by a shift of the above power laws from T−1/4 towards T−1/2. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Serotonin and its type-4 (5-hydroxytryptamine4) receptor play a major role in the physiology of the gastrointestinal tract. The effect of intravenous and/or oral tegaserod, a 5-hydroxytryptamine4 receptor partial agonist, on gastric emptying, small bowel transit and colonic transit has not been studied in detail in humans.〈section xml:id="abs1-2"〉〈title type="main"〉Aim:To assess the pharmacodynamic effects of repeated oral and intravenous administration of tegaserod on gastric emptying and small intestine and colonic transit.〈section xml:id="abs1-3"〉〈title type="main"〉Methods:A randomized, placebo-controlled, double-blind, three-way, crossover study of 6 mg oral and 0.6 mg intravenous tegaserod in 12 healthy male subjects was performed. Each treatment arm of the study involved 3 days of twice-daily administration and 1 day of daily administration of the study drugs.〈section xml:id="abs1-4"〉〈title type="main"〉Results:In comparison with placebo, oral and intravenous tegaserod significantly increased the gastric emptying rate (P 〈 0.01), accelerated colonic filling (P 〈 0.01) and shortened colonic transit at 48 h (P 〈 0.05). Tegaserod shortened the small intestine transit time by 30% after oral and by 37% after intravenous administration.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:In healthy subjects, tegaserod markedly accelerated gastric emptying and small intestinal transit, and induced a small but significant acceleration of colonic transit. Tegaserod can act as a promotile agent throughout the gastrointestinal tract.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9605
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract From the early days of high-temperature superconductivity on, the question of a possible role of apical sites in p-type superconductors has been controversely discussed in the community. Several recent observations made by us, using polarization-dependent O1s and Cu2p near-edge X-ray absorption spectroscopy on single crystals of infinite-layer compounds, of Ca-doped T′ phase compounds, and of Y1−x Ca x Ba2Cu3O y , are all consistent with the conjecture that there is significant influence of the apical site on high-T c superconductivity. Most notably, the Ca-dependent hole counts for the latter family show that superconductivity is absent if there are no holes on the apical site. This is independent of the hole count in the CuO2 planes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-7357
    Keywords: 79.60.Bm ; 73.20.Dx ; 74.70.Ad ; 74.80.Dm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Substituting Y in orthorhombic (Y,RE)Ba2Cu3O7 by any rare-earth element RE has generally little effect on the superconducting properties. For RE = Pr, however, superconductivity is completely suppressed. To elucidate this effect we have studied the unoccupied electronic structure of PrxY1−xBa2Cu3O7−y (x = 0.0,0.4, 0.8) by polarization-dependent O1s x-ray absorption spectroscopy on detwinned single crystals. Along with the comparison of undoped (y ≈ 0.9) to the doped materials (y ≈ 0.1), this allows a test of the current theoretical explanations for the suppression of superconductivity. While we can rule out models involving hole filling or charge transfer from planes to chains our data is consistent with approaches based on Pr4f−02pπ hybridization.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Strain Measurement with High-Temperature Strain Gauges in a Non Steady Temperature Field Considering a Two Dimensional Strain FieldTo confirm a FEM-simulation the strain fields at the surface of the hub of a shrink fit are measured during the thermal fitting process. The temperature changes during the fitting process between 420°C and 20°C. Because of the rotation symmetry a two dimensional strain field yields on the surface of the hub. The strain gauge type LF 30 is used. The temperature-dependence could not compensate in a half-bridge compensation-circuit. Because of this each strain gauge application must be calibrated individually. The experimental data is extremely close to the results predicted by the numerical simulation. This is an experimental confirmation of the FEM-simulation.
    Notes: Mit dem Ziel einer experimentellen Verifikation einer FEM-Simulation soll das Dehnungsfeld an der Nabenoberfläche beim thermischen Fügen von Preßverbindungen gemessen werden. Während der Dehnungsmessung wird an der Meßstelle der Temperaturbereich 420°C bis 20°C durchlaufen. Aufgrund der Rotationssymmetrie liegt an der Nabenoberfläche ein zweiachsiges Dehnungsfeld vor. Zur Messung werden Hochtemperatur-Dehnungsmeßstreifen (HT-DMS) vom Typ LF 30 eingesetzt. Der Temperaturgang kann wegen der Meßaufgabe schaltungstechnisch nicht kompensiert werden. Deshalb wird für jede DMS-Applikation eine individuelle Kalibrierung durchgeführt. Abschließend werden die Meßergebnisse mit Werten verglichen, die mit einer den Fügevorgang simulierenden FEM-Rechnung ermittelt werden. Es werden große Übereinstimmungen zwischen den gemessenen und berechneten Werten erzielt. Damit liegt ein experimenteller Nachweis der FEM-Simulation vor.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In Gaswirbelschichten wurden Häufigkeits- bzw. Wahrscheinlichkeitsverteilungen der Dichte der Mischphase, der Blasengröße sowie der Druckschwankungen in Abhängigkeit von der Gasgeschwindigkeit, Korngröße und dem Abstand vom Anströmboden durch Absorptionsmessung von Röntgenstrahlen, β-Strahlen und Licht sowie durch Messungen mit einer Drucksonde untersucht. Die Abhängigkeit der mittleren Dichte und der Intensität der Dichteschwankungen der Mischphase von der Gasgeschwindigkeit und der Korngröße konnte gesetzmäßig erfaßt werden. - Durch rheologische Messungen mit einem Rotations-viscosimeter wurde das Reibungsgesetz für „stabile“ Mischphasen ermittelt und seine Abhängigkeit von der Gasgeschwindigkeit und der Korngröße bestimmt. Der bei „instabilen“ Mischphasen beobachtete unregelmäßige Verlauf der Fließkurven konnte auf die Änderung der Dichte und Struktur der Mischphase zurückgeführt werden.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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