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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 22 (1983), S. 5978-5981 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 287-288 (Aug. 1998), p. 243-246 
    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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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 23-24 (Jan. 1992), p. 285-302 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 63 (1996), S. 93-101 
    ISSN: 1432-0630
    Keywords: 81.40 Z ; 81.60 Z ; 61.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Holes drilled in metals and silicon using different short-pulse lasers (copper vapour, Nd : YLF and titanium: sapphire) were characterized under optical and electron microscopy. The aim was to analyze and compare the thermal and mechanical effects on materials induced by laser drilling with a wide range of pulse widths (50 ns to 200 fs) and power densities (108 W/cm2 to 1015 W/cm2). Heat affected structural zones around micro-holes drilled in cold-rolled copper were revealed by analyzing ion-polished hole sections in the scanning electron microscope using electron channelling contrast. The heat affected zones were found to have a maximum width of 5 μm to 10 μm, independent of the duration of the pulses. Mechanically and thermally induced deformations and slip phenomena, including “prismatic punching”, were observed in laser-drilled molybdenum monocrystals. The dislocation arrangement which developed during laser drilling of silicon monocrystals was visualized by transmission electron microscopy. The microscopic studies showed that for percussion drilling in the high fluence range characterized by high ablation rates of a few micrometres per pulse the use of shorter pulses (τH 〈 50 ns) did not lead to any appreciable reduction in the melt component, material re-deposition or thermal load on the wall of the hole. In addition, the increasing mechanical loads on the material due to the higher pressure in the drill channel becomes a limiting factor for the precision of the processing.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 63 (1996), S. 93-101 
    ISSN: 1432-0630
    Keywords: PACS: 81.40 Z ; 81.60 Z ; 61.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  Holes drilled in metals and silicon using different short-pulse lasers (copper vapour, Nd : YLF and titanium : sapphire) were characterized under optical and electron microscopy. The aim was to analyze and compare the thermal and mechanical effects on materials induced by laser drilling with a wide range of pulse widths (50 ns to 200 fs) and power densities (108 W/cm2 to 1015 W/cm2). Heat affected structural zones around micro-holes drilled in cold-rolled copper were revealed by analyzing ion-polished hole sections in the scanning electron microscope using electron channelling contrast. The heat affected zones were found to have a maximum width of 5 μm to 10 μm, independent of the duration of the pulses. Mechanically and thermally induced deformations and slip phenomena, including “prismatic punching”, were observed in laser-drilled molybdenum monocrystals. The dislocation arrangement which developed during laser drilling of silicon monocrystals was visualized by transmission electron microscopy. The microscopic studies showed that for percussion drilling in the high fluence range characterized by high ablation rates of a few micrometres per pulse the use of shorter pulses (τH〈50 ns) did not lead to any appreciable reduction in the melt component, material re-deposition or thermal load on the wall of the hole. In addition, the increasing mechanical loads on the material due to the higher pressure in the drill channel becomes a limiting factor for the precision of the processing.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 150 (1991), S. 503-506 
    ISSN: 1432-1076
    Keywords: Dopamine infusion ; Newborn infants ; Plasma catecholamines ; Noradrenaline ; Adrenaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Newborn infants (21 preterm and 13 term) received dopamine infusions at a low (2.5–3.4 μg/kg per min) and/or high (5–10 μg/kg per min) infusion rate and changes in plasma catecholamines were monitored. The mean baseline values for dopamine, noradrenaline and adrenaline were between 240 and 560, 125 and 144 and 62 and 82 pg/ml, respectively. During low-rate infusion of dopamine, there was a significant increase in plasma dopamine (20–100fold), noradrenaline (three- to five-fold) and adrenaline (threefold). Administration of dopamine at the high rate resulted in an even larger increase in the plasma catecholamines (dopamine, 100–300fold; noradrenaline, seven- to eightfold; adrenaline, four- to sixfold). In a double-log plot, there was a highly significant correlation between the plasma concentrations of dopamine and noradrenaline (r=0.77;P〈0.001). In conclusion, infusion of dopamine in term and preterm newborn infants is accompanied by an enhanced sympatho-adrenal tone which may contribute to the cardiovascular effects of dopamine in these patients.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 27 (1995), S. 1313-1318 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Protective coatings with hard metal-like wear properties could be obtained by laser beam surfacing of powder mixtures consisting of coarse-grained tungsten carbide and a nickel or cobalt hard alloy. The microstructure of the clad composite layers was investigated by metallography and SEM. The four coating systems produced were found to differ strongly in the degree of partial carbide dissolution and the formation of new hard phases. This also influences the hardness and wear behaviour.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 18 (1980), S. 39-47 
    ISSN: 1741-0444
    Keywords: Cerebral blood flow ; Isotope clearance ; Noninvasive technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The validity of atraumatic measurements of regional cerebral blood flow (r.c.b.f) by intravenous injection of Xenon 133 has been studied in 17 patients with cerebrovascular diseases. The results were directly compared with those obtained in the same subjects using the intracarotid-injection method. Clearance curves obtained by the intravenous method were analysed by means of a bicompartmental model of blood circulation corrected for recirculation of the tracer. Use of different modes of intravenous injection and systematic analysis of the portion of the clearance curve usable for estimation of regional cerebral blood flow enabled the authors to define the optimal conditions for measurement of r.c.b.f. in subjects with cerebrovascular disorders. A predominant source of error was found to be the difficulty in defining the exact instant when clearance begins. As a result, the best conditions were as follows: slow injection (1 min) of tracer and analysis of the portion of clearance curve between 3 and 11 min after the beginning of the clearance. Under these conditions this atraumatic method is as precise in subjects with cerebrovascular disease as in those with normal cerebral circulation.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 27 (1996), S. 246-251 
    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: Hard Particle Dissolution and Structure of Coarsegrained Dispersion Layers on Steel Produced by Convection-reduced Laser MeltingWith the aim to produce hard and wear-resistant dispersion layers coarse grained TiC-and TiB2-particles were incorporated into the surface layers of steels by means of a two-step laser melting process with reduced melt bath convection. The influence of the carbon conent of the steel and content of alloying elements and hard particles in the screen printed layer on solidification structures and particle dissolution was investigated by optical and electron microscopy and x-ray microanalysis. The produced layers were also characterized by hardness measurements.
    Notes: Mit dem Ziel, harte und verschleißfeste Dispersionsschichten zu erzeugen, wurden in die Oberfläche von Stahlproben grobkörnige TiC- und TiB2-Partikel nach einem zweistufigen Prozeß mit Hilfe eines CO2-Leistungslasers eingeschmolzen. Die Laserbehandlung erfolgte derart, daß eine Schmelzbadkonvektion weitgehend unterdrückt werden konnte. Der Einfluß des Kohlenstoffgehaltes im Stahl sowie der Art und der Gehaltes von metallischen Zusätzen und Hartstoffen in der Vorbeschichtung auf die Hartstoffauflösung und die Ausbildung der Schichtgefüge wurde mittels Lichtmikroskopie, Rasterelektronenmikroskopie und Röngenmikroanalyse untersucht. Außerdem wurden zur Schichtcharakterisierung Härtemessungen durchgeführt.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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