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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 958-960 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman spectra were taken of cubic boron nitride (c-BN) crystals with diameters between 100 nm and 1 mm. The Raman line shape of the optical phonons was found to become increasingly asymmetric towards lower frequency shifts, broader and weaker with decreasing crystal diameters. The results can be explained in terms of a spatial correlation model. The corresponding correlation lengths lie in the nanometer range, i.e. several orders of magnitude below the actual crystallite sizes as determined by electron microscopy, thus revealing a high defect density. An additional examined typical c-BN film on a Si(100) substrate exhibits even weaker and broader structures consistent with an even higher defect density. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9071
    Keywords: Key words. Phagocytosis; cyclosporine A particles; morphometry; latex particles.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The aim of this study was to develop an in vitro model to estimate the clearance of pulmonary administered cyclosporine A (CsA). To do this we estimated the volume of CsA particles phagocytosed by alveolar macrophages (AM) lavaged from hamsters. AM were cultured with CsA particles at two doses of particles (0.1 mg or 0.5 mg) and at three incubation times (1 h, 6 h or 24 h). The AM were also incubated with or without latex particles. After incubation, AM were processed for light and electron microscopy and the mean volume of phagocytosed particles was esti mated stereologically from micrographs of the cells. Here, however, the CsA particles were dissolved during the embedding process and only their negative images (vacuoles) could be detected. An indirect method was therefore developed. The volume of cytoplasmic vacuoles (called 'background' vacuoles) was estimated in control macrophages (without particles or with latex particles and subtracted from the total volume of vac uoles in macrophages incubated with CsA, which gave the volume of phagocytosed CsA. The volume of the 'background' vacuoles remained constant in all study conditions. At a dose of 0.1 mg CsA the volume phagocytosed per macrophage was 13.83 μm3 at 1 h, 8.43 μm3 at 6 h and 4.50 μm3 at 24 h. At a dose of 0.5 mg CsA, the volume phagocytosed varied from 26.59 μm3 at 1 h, to 4.13 μm3 at 6 h and 49.10 μm3 at 24 h. These results show no statistically significant dependence on time for either dose, and a statistically significant dose effect only at 24 h. With latex particles, the phagocytosed volume increased significantly with time and dose and was significantly higher than for CsA particles. This study showed that CsA particles are phagocytosed by AM from hamsters but to a lesser extent than latex particles. This difference could be correlated with physical properties, i.e. a difference between particle size and shape and/or chemical properties, latex particles being inert and CsA particles being peptidic. Moreover, different surface receptors on AM could be involved in the process of phagocytosis of CsA and latex particles.
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 287-288 (Aug. 1998), p. 193-200 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 125 (1997), S. 283-286 
    ISSN: 1436-5073
    Keywords: thin film deposition ; magnetron sputtering ; hard coatings ; boron nitride ; electron microscopy ; electron energy loss spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of BN films was deposited by means of r.f. magnetron sputtering of a h-BN target onto Si(1OO) surfaces. Hereby, the substrate bias voltage was varied. Special interest is focussed to the influence of the deposition parameters on the orientation of the growing hexagonal BN film with respect to the substrate. For structural investigation, cross section samples were prepared. In addition to HRTEM and diffraction investigations, especially electron energy loss spectroscopy (EELS) was applied successfully for phase identification. For negative bias voltages of U B =−300 V and U B =−350V, we found a phase system consisting of a first-grown 25 nm thick layer of hexagonal structure with the c axis parallel to the substrate surface followed by the cubic phase.
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  • 5
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The investigation of the surface composition of vanadyl pyrophosphate catalysts and the influence of Cs ions and of water vapor on the surface P/V ratio were described and discussed. The characterization was carried out by XPS (X-ray Photoelectron Spectroscopy) and ISS (Ion Scattering Spectroscopy). It was concluded that the P/V ratio on the surface of equilibrated and non equilibrated (VO)2P2O7 catalysts prepared in aqueous solution was between 1.3 and 1.4 (XPS) based on calibrations with different VPO glasses as standard materials having uniform composition of surface and bulk. In the outermost layer of the catalyst the P/V ratio was much higher and laid between 2 and 3 as verified by ISS. Different influences, i.e. addition of alkali metall ions (Cs+) or a treatment with water vapor of the catalyst, caused a further increase in the concentration of phosphorus on the surface.
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  • 6
    ISSN: 1573-6822
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-6822
    Keywords: cell activation ; cell viability ; cyclosporin ; phagocytosis ; stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The aim of this study was to compare two types of cyclosporin (Cs) particles, SDZ OXL 400 and SDZ IMM 125, the latter being more hydrophilic, to understand their uptake by airway macrophages. Alveolar macrophages (AM), harvested by bronchoalveolar lavage (BAL) of hamster lungs, were cultured with two different doses (0.1 mg and 0.5 mg) for 1 h, 6 h, and 24 h. Control incubations without Cs particles or with latex particles were carried out simultaneously. Cell viability, cell activation (i.e., respiratory burst, interleukin-6 (IL-6) synthesis) and mean volume of particles phagocytosed per macrophage were measured. Both types of Cs particles did not modify the AM viability, and failed to induce IL-6 synthesis during phagocytosis but slightly decreased the cell oxidative respiratory burst. The comparison between SDZ OXL 400 and SDZ IMM 125 showed that for the lower dose the mean volume of both Cs types phagocytosed was similar at 1 h and 6 h. At 24 h an increase of the mean volume phagocytosed was seen for SDZ IMM 125 but not for SDZ OXL 400. For the higher dose the mean volume of SDZ IMM 125 phagocytosed was higher than SDZ OXL 400 at 1 h and 6 h and comparable for both types at 24 h. SDZ IMM 125 particles were phagocytosed more rapidly than SDZ OXL 400. The mean volume of phagocytosed latex particles increased with time and dose and was higher than for both Cs particle types. In conclusion, AM were seen to phagocytose particles of different physical properties (i.e., form, size, and shape), chemical properties (i.e., inert or peptidic) and degrees of hydrophilicity in a different manner.
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  • 8
    ISSN: 1573-6822
    Keywords: human ; in vitro ; nasal mucosa ; octreotide ; Sandostatin®
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Anin vitro human nasal model was developed as a tool to study the local tolerabiliity of nasal powder forms using excised nasal mucosa in a diffusion chamber. The suitability of this model was tested using Sandostatin® (SMS) an octapeptide analog of somatostatin, as a reference drug enhanced by Avicel® (microcrystalline cellulose) or lactose (100 mesh). The standard nasal spray vehicle was taken as a harmless control and 1% chenodeoxycholate (CDC) as a harmful control in terms of local tolerability. The extent of peptide permeation was determined by measuring SMS concentration in the receiving chamber. The labeling of SMS was detected by immunoperoxidase staining on cross sections. The local tolerability for all tested forms was assessed by histopathological examination and scanning electron microscopy. The apparent permeation coefficient allowed us to rank the absorption of the tested drug forms as Avicel 〉 spray=lactose〉1%CDC. For all formulations, SMS was detected in the epithelium. No changes of the nasal mucosa could be observed with Avicel, lactose or nasal spray vehicle in the presence or absence of SMS. 1%CDC with or without drug showed an immediate destruction of the nasal epithelium. The validation of thisin vitro model using human nasal mucosa will be further discussed as a tool for assessing the local tolerability of intranasally applied test substances.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 736-741 
    ISSN: 0142-2421
    Keywords: vanadyl pyrophosphate catalysts ; XPS ; ISS ; surface P/V ratio ; Cs+-doped (VO)2P2O7 catalysts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface composition of (VO)2P2O7 catalysts was investigated by x-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). The P/V ratio on the surface of (VO)2P2O7 catalysts from aqueously prepared precursors lies between 1.3 and 1.4, based on XPS calibrations with different VPO glasses as standard materials. With ISS we obtained a higher P/V ratio of (VO)2P2O7 catalysts in the outermost layer of ∽2-3.The addition of caesium (Cs+) caused a further increase in the P/V ratio of the surface of (VO)2P2O7 with increasing Cs+ concentration. Ion scattering spectroscopy indicated that Cs+ was mainly confined to the uppermost layers, and at high doping concentrations a total surface coverage with Cs+ was achieved.The influence of water vapour on the surface composition of the catalysts was also investigated. A migration and a loss of phosphorus was found after and during water vapour treatment using XPS, ISS and thermogravimetric measurements. The surface of (VO)2P2O7 is assumed to be a dynamic system influenced by the partial pressure of water vapour in the gas phase. The rate of bulk oxidation of (VO)2P2O7 was dependent on the water vapour content in the gas phase. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
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  • 10
    Publication Date: 1997-04-07
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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