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  • 1
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 131-133 (Oct. 2007), p. 619-624 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The crystallographic structure of semiconductor - insulator - semiconductor (SIS) structuresconsisting of a Si(111) substrate, Pr2O3 and Y2O3 insulating high-k materials, and Si cap layerwas characterized by a combination of X-ray pole figure measurement and conventional X-ray diffraction.Oxide and Si cap layer were grown by molecular beam epitaxy and have the same 111 latticeorientation as the substrate. It is shown that the oxide layers grow in a type B stacking orientationonly, while the epi-layer exhibits exclusively the same type A orientation as the substrate. Asmall fraction of the epi-Si lattice was identified with 511 netplanes parallel to the surface. TEMinvestigations identify these areas as structural defects between Si grains of differing stacking sequence
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Propanidid ; Liposomen ; Propofol ; Hämodynamik ; Histamin ; Katecholamine ; Key words Propanidid ; Liposomes ; Propofol ; Haemodynamics ; Histamine ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background. Propanidid was widely used as a short-acting i.v. anaesthetic until it was withdrawn due to severe haemodynamic side effects. It was presumed that anaphylactoid reactions with massive histamine release were caused by the solvent cremophor rather than by propanidid itself. A new liposomal preparation of propanidid was examined in this animal study and compared with propanidid in cremophor solution and with propofol. Methods. Eighteen pigs were randomly assigned to one of the following groups: Group 1 (n=6): Propanidid in liposomal preparation (PropaLip; Braun Melsungen, Germany). Anaesthesia was induced with 60 mg/kg, followed by continuous infusion of 400 mg/kg·h. Group 2 (n=6): Propanidid in cremophor solution (PropaCrem; Sombrevin, Gedeon Richter, Budapest) 15 mg/kg, 100 mg/kg·h. Group 3 (n=6): Propofol (Disoprivan, Zeneca, Plankstadt, Germany) 5 mg/kg, 20 mg/kg·h. After induction and tracheal intubation, the animals were ventilated with 50% oxygen in air. Basic monitoring included noninvasive blood pressure measurements, electrocardiographic monitoring, and capnography. In a short surgical procedure, arterial and pulmonary artery catheters were placed via the right carotid artery and right internal jugular vein, respectively. As soon as the animals responded to a pain stimulus a second anaesthetic induction was performed, followed by a 60-min continuous infusion of the agent studied with invasive haemodynamic monitoring including arterial and pulmonary arterial pressures and cardiac output. Blood samples were taken for the measurement of serum levels of adrenaline, noradrenaline, cortisol, aldosterone, adrenocorticotropic hormone, and histamine. Results. Intubation conditions and quality of anaesthesia were best in propofol animals, followed by PropaCrem animals. In spite of the large dose of 410 mg/kg·h, resulting in a volume load of as much as 16.4 ml/kg·h, the PropaLip animals showed evidence of poor anaesthetic quality. In group 1 we recorded the highest increases in heart rate (91 vs. 115/min), cardiac output (5.4 vs. 7.7 l/min), plasma catecholamine levels, and histamine concentrations (124–268 ng/ml). Conclusions. In our animal study, propanidid in liposomal preparation failed to show promise as a new anaesthetic agent. Our results are discussed in view of a drug targeting the cells of the reticuloendothelial system, especially the liver, where liposomes are eliminated from the blood. This may result in the transport of propanidid to one of its major places of inactivation.
    Notes: Zusammenfassung In einer tierexperimentellen Studie wurden 18 Läuferschweine untersucht, von denen je 6 Tiere (1) Propanidid in Liposomendispersion (abgekürzt PropaLip), (2) Propanidid in Cremophor (abgekürzt PropaCrem) und (3) Propofol erhielten. Nach Narkoseeinleitung mit 60 mg/kg PropaLip, 15 mg/kg PropaCrem bzw. 5 mg/kg Propofol wurden die Tiere intubiert, für die weiteren Messungen instrumentiert und in einer anschließenden 60minütigen Narkose untersucht. Der Anästhetikaverbrauch betrug 16 mg/kg·h Propofol, 120 mg/kg·h PropaCrem und 410 mg/kg·h PropaLip. Trotz dieser hohen Dosierung und der damit verbundenen Volumenbelastung von 16,4 ml/kg·h war die Anästhesiequalität in der PropaLip-Gruppe unbefriedigend. Bei diesen Tieren traten die ausgeprägtesten Anstiege von Herzfrequenz, HZV, Katecholamin- und Histaminspiegeln auf, weitgehend konstant blieben die genannten Parameter bei der Propofolgruppe, während die PropaCrem-Tiere eine Mittelstellung einnahmen. Offenbar ist die Verfügbarkeit von Propanidid in der Liposomenpräparation schlechter als in der Cremophorlösung. Ein Zusammenhang der geringen Wirksamkeit mit der gezielten Aufnahme von Liposomen in die Zellen des RES, z.B. der Leber, wo Propanidid inaktiviert wird, wird diskutiert.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0649
    Keywords: 42.60.By ; 42.65. — k ; 42.79.Fm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We demonstrate the optical Kerr shutter technique as a simple and powerful tool for the measurement of femtosecond pulses in the ultraviolet as well as in the visible spectral region. The method provides the third-order intensity correlation function which gives information about pulse asymmetry and pulse structures.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1017
    Keywords: Key words Gallstone ; Cholesterol monohydrate crystals ; Phase separation ; Light scattering ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Phospholipid/cholesterol vesicles were solu-bilized by 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Above 30 mol% cholesterol (Ch) in the lipid vesicles several remarkable changes of the solubilization process were observed. (i) Two modes of solubilization: The effective detergent to lipid ratio Rc(M) for the formation of mixed micelles decreased from Rc(M) = 43 ± 3 at low lipid concentrations, [L]≤ 0.15 mm, to Rc(M) = 2.4 ± 0.3 above [L] = 0.5 mm (40 mol% Ch, T = 20 °C). (ii) At subsolubilizing CHAPS concentrations, filamentous and helical microstructures were formed, similar to those which were observed in native and model bile. (iii) The number of observed fibers was about two orders of magnitude higher in the presence of the negatively charged lipids phosphatidylglycerol (PG) and phosphatidic acid (PA) compared to the zwitterionic phosphatidylcholine (PC). Fiber formation began after 16–18 h using PG and PA compared to 3–4 days in the presence of PC. Screening of the charged lipids by NaCl effectively reduced the formation of fibers. Assuming binding of Na+ to the charged lipid aggregates, an intrinsic binding constant Kint = 0.6 M–1 was determined by applying the Gouy-Chapman theory. After the addition of CHAPS to PG/Ch vesicles, a fast initial solubilization of the vesicles (〈1 min) to mixed micelles (rh = 2.3 ± 0.2 nm) and small vesicles (rh = 23 ± 1 nm) was observed, followed by an intermediate period of 2 h, after which the formation of fibers occurred (〉15 h). The microstructures are visualized by darkfield and electron microscopy. The method of vesicle solubilization is compared to the dilution of concentrated micellar solutions, which is usually applied to model bile systems.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 108-109 (Dec. 2005), p. 741-748 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The use of heteroepitaxial Si / Pr2O3 / Si(111) systems as semiconductor-insulatorsemiconductor (SIS) stacks in future applications requires a detailed structural characterization. We used X-ray reflectivity (XRR) to control layer thickness and interface roughness, standard X-ray diffraction (XRD) to analyze the Pr2O3 phase, orientation and crystal perfection, and grazing incidence XRD to study the thin epitaxial Si top layer. Transmission electron microscopy (TEM) was used to prove the results by direct imaging on a microscopic scale. Pr2O3 grows epitaxially in its hexagonal phase and (0001) orientation on Si(111) substrates. An epitaxial Si overgrowth in (111) orientation and good perfection is possible, but such Si layers exhibit two stacking twins, one with the same in-plane orientation as the substrate and one rotated by 180° around the Si [111] direction
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    BBA - Protein Structure 536 (1978), S. 184-196 
    ISSN: 0005-2795
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 12485-12490 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 9823-9830 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 9067-9077 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vibrational excitation of an Ar55 cluster in collisions with He (Ekin=25 meV) is investigated by using classical trajectories and a highly approximate quantum mechanical method (vibrationally sudden approximation). The energy transfer from the helium atom to the cluster (ΔE) is calculated as a function of the scattering angle θ. It is found (i) that predominantly the modes corresponding to the cluster atoms in the outer shell are excited and (ii) that the probability for multi-phonon (Δn≥2) excitations steadily increases with the scattering angle. The results of both sets of calculations are generally in good agreement with measured energy loss spectra over the entire range of scattering angles. In the region θ(approximate)15°–30°, which—because single-phonon transitions dominate—is most important for determining the frequency distribution of the cluster, the quantum mechanical calculations are superior to classical mechanics; the latter fails to conserve zero-point energy and therefore leads to unrealistic energy transfer below ΔE(approximately-less-than)2 meV. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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