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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 66 (1998), S. S187 
    ISSN: 1432-0630
    Keywords: PACS: 87.64.Dz; 61.46.+w; 73.23.Hk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1432-0630
    Keywords: PACS: 07.79.C; 61.16.C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. An internal reflection mode is introduced for scanning near-field optical microscopy (SNOM) with the tetrahedral tip. A beam of light is coupled into the tip and the light specularly reflected out of the tip is detected as a photosignal for SNOM. An auxiliary STM mode is used to control the distance during the scanning process and to record the topography of the sample simultaneously with the SNOM image. Images were obtained of different metallic samples which show a contrast in the order of 10% of the total reflected photosignal. In images of metallic samples an inverted contrast is consistently obtained compared to images previously obtained of comparable samples in a transmission mode. The contrast shows a pronounced dependence on the polarization of the incident beam with respect to the orientation of the edges of the tip. In the case of gold surfaces, the photosignal as a function of distance between the tip and the surface shows a pronounced peak in the near-field range of 0–20 nm which is tentatively attributed to the excitation of surface plasmons on the gold surface. The pronounced near-field effects and the strong contrast in the near-field images and the resolution well below 50 nm are an indication of a highly efficient coupling of the incident beam to a local excitation of the tip apex which is essential for the function of the tip as a probe for SNOM.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1432-0649
    Keywords: PACS: 07.60.Pb; 42.30; 77.80.Dj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1434-601X
    Keywords: 25.70.Gh ; 25.70.Jj ; 25.70.Pq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In a multidetector experiment on 26 or 30 AMeV32S+58Ni, up to four coincident heavier or intermediate-mass fragments were observed. One of these occasionally has the characteristics of a projectile-like fragment, up to three may be attributed to the decay of the heavy reaction product. Taking the velocity of the fragments as a measure of the heavy-product excitation energy, one finds evaporation, fission and multifragmentation to follow one another with rising excitation. Model simulations of sequential decay with up to two binary fissions and, alternatively, of simultaneous statistical multifragmentation were performed for comparison with experimental distributions of mass, velocity and (for events with three slow intermediate-mass fragments) relative azimuthal angle. Though in the three-fragment events indications of simultaneous multifragmentation are present, the sequential binary decay predominates. Evaporated protons and α particles detected in coincidence have a mean multiplicity growing with excitation energy, while the temperature governing the spectra has a plateau with a value of about 5.5 MeV.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1435-1803
    Keywords: Frank-Starling ; mechanism ; heart failure ; normal donor hearts ; dilated cardio-myopathy ; heart transplantation ; skinned fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The Frank-Starling-mechanism (FSM) was analyzed in isolated intact and skinned human left ventricular myocardium obtained from 11 heart transplantations (normal donor hearts (NDH), n=8; dilated cardiomyopathy (DCM), n=11). The new technique to utilize muscle strips from normal donor hearts which were actually implanted is described in detail. Methods I) In electrically stimulated left ventricular trabeculae (37°C, oxygenated Krebs-Henseleit solution, supramaximal, electrical stimulation, frequency 1 Hz) force development was analyzed as a function of muscle length (NDH=8; DCM=11). II) In an additional series left ventricular myocardium was demembranized (“skinned”) by Triton-X-100. At different sarcomere lengths and calcium concentrations corresponding to pCa values of 4.3, 5.5, and 8.0 force development was measured (DCM=11; NDH=9). Results I) Developed force increased up to an optimum as a function of muscle length in intact NDH- and DCM-myocardium. However, the relative increment of developed force after any length step was smaller in DCM than in NDH. Near “Lmax” (muscle length associated with maximum developed force) passive resting tension was considerably elevated in DCM, indicating significantly incresed diastolic stiffness II) In skinned left ventricular DCM- and NDH-myocardium developed force depended on sarcomere length with an optimum near 2.2 μm. However, a reduction of activator calcium concentration from pCa 4.3 to pCa 5.5 produces a smaller percent decline in force at short sarcomere lengths in DCM than it does in NDH. Conclusion the present study shows that except for diastolic stiffness and a smaller relative force increment after any, length step in DCM the Frank Starling mechanism is still present in isolated human left ventricular DCM-as in NDH-myocardium. The current study does not allow to decide whether in skinned myocardium the smaller percent decline in force after reduction of activator calcium concentrations in DCM is caused by an increased calcium sensitivity at short sarcomere lengths or decreased sensitivity at long sarcomere lengths.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 320-327 
    ISSN: 1573-1626
    Keywords: MHD ; stability ; bifurcations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract A series of numerical studies on the behaviour of magnetic fields and motions in a spherical body of an electrically conducting incompressible fluid have been carried out. The magnetic field was assumed to be maintained by a given electromotive force inside the body and to continue as a potential field in outer space. In view of the motion an external forcing was taken into account, and boundary conditions were considered which correspond to a stress-free surface. The stability of several steady states has been studied as well as the evolutions starting from unstable states. In this paper a configuration with a poloidal magnetic field and a differential rotation, both symmetric about the same axis, is considered. This configuration is stable only for sufficiently small Hartmann numbers but evolves, if disturbed, in the case of larger Hartmann numbers toward a non-axisymmetric state. In this case the well-known symmetrization effect of differential rotation in magnetic fields is destroyed.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 306-315 
    ISSN: 0142-2421
    Keywords: polycarbonate ; SF6 ; plasma ; XPS, SFM ; AFM ; mass spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A systematic investigation was made of the chemical and morphological influences of SF6 plasma on polycarbonate and the influence of plasma treatment on Al metallization. Mass and ion spectroscopy were used for characterization of the plasma and the etching process. X-ray photoelectron spectroscopy (XPS) measurements were applied for the chemical characterization, while atomic force microscopy (AFM) (static and dynamic mode) served to inspect the surface morphology. All analytical techniques were performed in an ultrahigh vacuum system, in order to prevent the polycarbonate sample from being exposed to ambient air after the plasma treatment. During the etching process we used mass difference spectra to demonstrate the removal of masses 19, 28 and 32 corresponding to HF, CO (N2) and CF. Additionally, the inclusion of fluorine was also observed by this technique.The XPS spectra of polycarbonate surfaces show a significant inclusion of fluorine (C-F, C-F2) and a reduction of the oxygen content after the plasma treatment. Aluminium metallization leads to the formation of an Al-F interlayer; metallic growth of Al is only observed when the metallic layers become thicker than a few nanometres.The AFM investigations have shown that even a short plasma treatment causes changes in morphology (structures with an extension of 20-40 nm). After extended plasma exposure the surface becomes very rough, resulting in poor Al adhesion. On untreated polycarbonate, Al grows in the form of weakly bound clusters, which can only be imaged in the dynamic AFM mode. After plasma treatment, Al grows in the form of well-adhering flat layers without clustering. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 416-425 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Atomic force microscopy (AFM) is applied on two different types of thin latex films. Polystyrene dispersion particles are prepared by various methods to form well-ordered monolayers and multilayers. Atomic force microscopy serves as a tool to study the surface structures of such films and to find the optimal preparation conditions. The micromorphology of the second system, an adhesive tape, was imaged successfully by AFM running in dynamic mode. Besides the morphological studies, the interaction between the sticky surface and the AFM tip is measured by the damping of the cantilever oscillation versus tip-sample distance.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 19
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 25 (1997), S. 537-542 
    ISSN: 0142-2421
    Keywords: scanning force microscopy ; polymers ; polyamide ; tensile tester ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The structure and the mechanical properties of polyamide (PA) films were studied with scanning force microscopy (SFM). The spherulitic structure of the films was resolved and the amorphous and crystalline regions could be identified without heavy metal staining or evaporation. The identification was achieved with different contrast mechanisms in SFM, such as the force modulation technique and phase imaging.The mechanical properties of the PA films were investigated with a tensile tester. The films were drawn in a uniaxial direction. The deformation of the spherulite structures could be imaged byin situ SFM. A schematic model for the interpretation of the observed structures is presented.© 1997 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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