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  • 1
    Electronic Resource
    Electronic Resource
    Minority-carrier kinetics in heavily doped GaAs:C studied by transient photoluminescence (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5072-5078 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room-temperature photoluminescence decay time measurements in heavily doped GaAs:C-layers designed as base layers for heterojunction bipolar transistors are reported. These measurements provide access to nonequilibrium minority carrier lifetimes that determine the current gains of those devices. By systematically studying transient luminescence spectra over a wide range of excitation densities between 1013 and 1018 cm−3, we demonstrate the importance of carrier trapping processes at low excitation densities. Optimized excitation conditions that achieve trap saturation but also avoid stimulated emission are found for densities of (1–3)×1017 cm−3/pulse. Detection is limited to a spectral window well above the energy gap (beyond 1.5 eV). Values for both Auger and radiative recombination coefficients are given. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1456244
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  • 2
    Electronic Resource
    Electronic Resource
    Gas-sensor properties of SnO2 films implanted with gold and iron ions (1997)
    Springer
    Journal of materials science 8 (1997), S. 301-306 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract SnO2 gas-sensor films were modified by implantation of gold and iron ions. The change in electrical resistivity of the films caused by inflammable gases, H2, CO, CH4 and C2H5OH, was measured in the temperature range 100–500°C, and compared to non-implanted films. The morphological changes caused by gold and iron ion implantation were also investigated by atomic force microscopy. After ion implantation and annealing at 600°C, the sensitivity to H2 and CO gas was found to increase, and the dynamic range of the sensitivity to ethanol was improved. The sensitivity to CH4 was low before and after ion implantation. Fe2O3 (3%SnO2) film was also modified by gold ion implantation for comparison.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018535322380
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  • 3
    Electronic Resource
    Electronic Resource
    Growth of anchorage-dependent mammalian cells on microstructures and microperforated silicon membranes (1996)
    Springer
    Journal of materials science 7 (1996), S. 85-97 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Anchorage-dependent cells (mouse fibroblasts L929 and 3T3) were cultivated on microstructures made by semiconductor technology. Both cell lines showed normal growth on silicon surfaces covered with microelectrode arrays as well as on microperforated silicon membranes with square pores made by anisotropic etching (5, 10 or 20 μm edge length at the top and 1.2, 6.2 or 16.2 μm at the bottom). The cells spread over the 5 and 10 μm pores, but mostly failed to cover the 20 μm ones. They were able to cross the silicon membrane through the pores and to grow and spread on the under side of the membrane. Small pores (about 1 μm2) impeded but did not prevent cells crossing the membrane. Medium and large pores were freely crossed. Negative dielectrophoresis was used to achieve accurate positioning of cells above pores or to repel them from the chip surface (a.c., square wave, 2.5 V peak-to-peak, 5 MHz). The results are discussed with respect to their microtool applications for single-cell technologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058719
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  • 4
    Electronic Resource
    Electronic Resource
    Separation of the reaction products of cyanazine and terbuthylazine nitrosation by thin-layer chromatography (1998)
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 679-682 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract N-Nitroso-triazine herbicide species were synthesized as reference standards and their reaction products were separated by TLC. The method was established for analytical as well as for preparative amounts to achieve a sufficient separation between the educts, the byproducts and the N-nitrosated moieties. Separation of the reaction mixture was performed by two-dimensional TLC, using different mobile phases for each dimension. In the second dimension two developments were executed using the same solvent mixture. To examine the quality of performance, the separation zones were scrapped off, extracted and analyzed in the HPLC-diode array detection (DAD) mode in comparison with standards of the educts and the products of their N-nitrosation. This method minimizes the contact with the resulting N-nitroso compounds. At present nothing is known about the toxicological relevance or risk assessment on human health of N-nitrosocyanazine or N-nitrosoterbuthylazine species. Therefore the practical handling of these putative mutagenic and carcinogenic substances should be seen under the aspect of precaution and prevention of contamination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050780
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  • 5
    Electronic Resource
    Electronic Resource
    Gold electrodes from recordable CDs for mercury quantification by flow injection analysis (2000)
    Springer
    Fresenius' journal of analytical chemistry 366 (2000), S. 444-448 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The development of a new methodology for the construction of very efficient flow cells for mercury detection by potentiometric stripping analysis, employing the thin gold layer of recordable CDs as working ¶electrode is reported. This new source of electrodes (CDtrodes) show very attractive performance, similar to that obtained with commercial gold electrodes, with superior versatility. The low cost of this new source of “gold electrodes” allows a frequent replacement of the electrode, avoiding cumbersome clean-up treatments. Various experimental parameters have been optimized to yield low detection limits (0.25 ng/mL of mercury for 5 min deposition at 0.3 V) and good precision (standard deviation of 1.9% was obtained for 15 repetitive measurements using 10 ng/mL of mercury). Standard curves were found to be linear over the range of 0.5–100 μg L–1 of mercury. The flow cells developed were used for the quantification of mercury in oceanic and tap water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050090
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  • 6
    Electronic Resource
    Electronic Resource
    Mischungen von primären aliphatischen Alkoholen mit Chlorex und anderen organischen Stoffen (1949)
    Springer
    Monatshefte für Chemie 80 (1949), S. 749-758 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Zusammenfassung 1. Die untersuchten Chlorex-n-Alkoholsysteme zeigen hohe endotherme Mischungswärmen, die sich mit steigender Temperatur noch vergrößern. 2. Bei den niederen Alkoholsystemen treten Volumkontraktionen, bei den höheren Volumdilatationen auf. 3. Das System Chlorex-Methanol ist in flüssiger Phase unbeschränkt mischbar; sämtliche anderen Alkoholsysteme besitzen Mischungslücken. Die KLT-Werte steigen mit wachsendem Molgewicht des Alkohols an, und zwar ab C3H7OH ziemlich regelmäßig oszillierend. 4. Mit steigendem Molgewicht der Alkohole verschieben sich die ΔH max-Werte in das Alkohol-reichere, dagegen die ΔV max- und KLT-Werte ins Chlorex-reichere Gebiet. Die Systemreihen n-Alkohole-Benzol und n-Alkohole-n-Hexan weisen ganz ähnliche Anomalien auf, die offenbar in der Assoziation und dem mit der Temperatur veränderlichen Assoziationsgrad der Alkoholkomponente begründet sind. 5. Chlorex stellt für die niederen n-Alkohole ein selektives Lösungsmittel dar, währendAnilin mit denselben Alkoholen (bis C8H17OH) in flüssiger Phase unbeschränkt mischbar ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00898375
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  • 7
    Electronic Resource
    Electronic Resource
    Über binäre flüssige Mischungen X (1949)
    Springer
    Monatshefte für Chemie 80 (1949), S. 510-516 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00899155
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  • 8
    Electronic Resource
    Electronic Resource
    Über die Mischbarkeit von Chlorex (β,β′-Dichlordiäthyläther) mit Halogenkohlenwasserstoffen (1949)
    Springer
    Monatshefte für Chemie 80 (1949), S. 856-863 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00898388
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  • 9
    Electronic Resource
    Electronic Resource
    Die Mischungen von Chlorex mit n-Oktan und 2,2,4-Trimethylpentan (1949)
    Springer
    Monatshefte für Chemie 80 (1949), S. 572-582 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Zusammenfassung 1. Die Mischungswärmen der SystemeChlorex—n-Oktan undChlorex—i-Oktan (2,2,4-Trimethylpentan) sind bei 25°C sehr starkendotherm (495, bzw. 440 cal/Mol Mischung bei XChl=0,300) und besitzen einennegativen Temperaturkoeffizienten. 2. Das SystemChlorex—n-Oktan zeigt bei 20°C — das heißt bei eben noch vollständiger gegenseitiger Löslichkeit — eine kleine Volums-dilatation, die sich mit steigender Temperatur (35°) vorerst nur wenig ändert, dann aber (50°) deutlich ausgeprägt ist. Das SystemChlorex—i-Oktan weist bei 20°C — also noch sehr nahe der KLT — eine geringfügige Volumskontraktion auf, die bei 35° noch ebenso gering ist, dann aber (50°) bemerkenswert groß wird. 3. Das Dipolmoment desChlorex-Einzelmoleküls errechnet sich bei 20°C zu 2,47 (Debye) in n-Oktan und 2,60 (Debye) in i-Oktan. 4. Die Zustandsdiagramme beider Systeme sind sehr ähnlich und zeigen tiefe, fast über den gesamten Konzentrationsbereich laufende Zonen beschränkter Mischbarkeit. Die KLT desChlorex—n-Oktan-systems liegt bei+19,7°C, die des i-Oktansystems bei+18,2°C. Für die Schmelzwärme vonChlorex finden wir als Mittelwert 2070 cal/Mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00899161
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  • 10
    Electronic Resource
    Electronic Resource
    Hydroxyapatite nucleation on Na ion implanted Ti surfaces (2000)
    Springer
    Journal of materials science 19 (2000), S. 1029-1031 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006782818468
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