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  • 1
    Electronic Resource
    Electronic Resource
    Detection of antigenic variation in influenza virus neuraminidase by the ESSEN-NIT and the WHO standard procedure (1978)
    Springer
    Medical microbiology and immunology 166 (1978), S. 165-171 
    Details
    ISSN: 1432-1831
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A new rapid modified micro-neuraminidase-inhibition test (ESSEN-NIT) has recently been described. This test was originally devised to facilitate largescale screening for serum antibodies to influenza virus neuraminidase. It was shown that this test yielded results comparable to those obtained with the WHO standard procedure. Our report presents data on the comparison between the WHO method and the ESSEN-NIT with respect to their capability in detecting antigenic differences in neuraminidase of various strains of influenza A viruses belonging to the H3N2 subtype family. Two antiserums against the N2 antigens of the A/Hongkong/1/68 (X15HK) and of the A/Port Chalmers/1/73 (X42) recombinant strains were used in characterization experiments. The results obtained indicate that the ESSEN-NIT is at least as sensitive in detecting antigenic variations of neuraminidase as the WHO standard procedure. The drift of the N2 enzyme which occurred as early as 1969 and is known to continue to date, could be clearly demonstrated. Major and minor antigenic changes of neuraminidase in representative influenza isolates were equally well detected by both assays. The ESSEN-NIT offers the advantage of speed, economy, and computerized evalutaion of data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02121146
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  • 2
    Electronic Resource
    Electronic Resource
    Schottky barrier and pn-junctionI/V plots — Small signal evaluation (1988)
    Springer
    Applied physics 47 (1988), S. 291-300 
    Details
    ISSN: 1432-0630
    Keywords: 73.30.+y ; 73.40.Lq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper proposes and examines three different plots for the determination of the saturation current, the ideality factor, and the series resistance of Schottky diodes and solar cells from the measurement of a single current (I)/voltage(V) curve. All three plots utilize the small signal conductance and avoid the traditional Norde plot completely. A test reveals that the series resistance and the barrier height of a test diode can be determined with an accuracy of better than 1%. Finally it is shown that a numerical agreement between measured and fittedI/V curves is generally insufficient to prove the physical validity of current transport models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615935
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of barrier inhomogeneities on noise at Schottky contacts (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1113-1115 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electronic properties of Schottky diodes depend sensitively on spatial inhomogeneities of the metal/semiconductor interface. We find that, contrary to previous theories for low-frequency noise, the electronic properties of Schottky contacts cannot be understood if one neglects spatial fluctuations of the Schottky barrier height. Our systematic investigation of several silicide/silicon diodes yields as an empirical law that excess noise increases drastically when the standard deviation σs of the spatial distribution of Schottky barrier heights exceeds the critical threshold value of 2kT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102584
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  • 4
    Electronic Resource
    Electronic Resource
    Direct observation of a scaling effect on effective minority carrier lifetimes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4168-4172 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effective minority carrier lifetime in semiconductors with recombination inhomogeneities depends on the spatial distribution of recombination sites and not only on their absolute number. We use time-resolved microwave reflection measurements to monitor the carrier recombination in silicon wafers with a periodic metallization pattern on one surface. This contact scheme simulates the distribution of sites of enhanced carrier recombination. The experiments reveal a sensitive dependence of the effective minority carrier lifetime on the interdistance and the size—i.e., the scaling—of the metallization pattern at fixed metallization area ratio. This so-called scaling effect occurs whenever the size and the interdistance of recombination sites are comparable to the minority carrier diffusion length. Our experiments are in good agreement with results from a new analytical three-dimensional simulation which is based on the solution of the electronic transport equations in Fourier space. Our model is applicable to the optimization of the backside ohmic contact pattern for high efficiency solar cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358450
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of the Pacing Rate on the Atrioventricular Conduction Time During Aerobic and Anaerobic Exercise: Basic Concepts for a Dromotropically Controlled Rate Responsive Pacemaker (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 22 (1999), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The dromotropic pacemaker concept needs a rate responsive algorithm in which the pacing rate is controlled by the atrioventricular conduction time (AVCT). To develop basic concepts for such a rate responsive algorithm, the influence of the pacing rate on the AVCT was investigated. Seven patients (62 ± 7.8 years) with sick sinus syndrome and intact atrioventricular conduction underwent two cardiopulmonary exercise tests (CPX) on a treadmill. According to the determination of the anaerobic threshold (AT) and the patients maximum capacity in the first incremental CPX the work rate for two exercise levels below and above the AT were chosen for the second constant workload CPX. The calculation of the optimal pacing rate (HRopt) was based on the oxygen uptake (VO2) during exercise after reaching steady-state conditions. According to the increase of the V2 from 14.8 ± 2.3 mL/min per kilogram during aerobic work (38.3 ± 16.0 W) to 19.4 ± 4.7 mL/min per kilogram during anaerobic work (80.6 ± 32.3 W), the HRopt was calculated to be 98.6 ± 6.9 beats/min and 116.4 ± 4.7 beats/min. Starting from HRopt, the pacing rate was increased (overpacing) and decreased (underpacing) by about 5 beats/min every minute. At optimal pacing rate the AVCT decreased significantly from 233.0 ± 30.5 ms during aerobic work and to 226.4 ± 27.3 ms during anaerobic work (P 〈 0.05). Whereas overpacing induced a significant prolongation of the AVCT during aerobic work (4.17 ± 1.78 ms per 10 beats/min) and anaerobic work (3.84 ± 1.60 ms per 10 beats/min), underpacing yielded a significant shortening of the AVCT by about 4.49 ± 2.64 ms per 10 beats/min during aerobic work and 4.75 ± 1.87 ms per 10 beats/min during anaerobic work (P 〈 0.01). The slopes of the regression lines of the relationship between AVCT and pacing rate were not significantly different. Based on the reciprocal relationship of heart rate (HR) and AVCT, basic concepts may be established for a dromotropic rate responsive algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1999.tb00411.x
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature dependence of Schottky barrier heights on silicon (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 1315-1319 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the temperature dependence of Schottky barrier heights on silicon. The analysis of a large variety of polycrystalline diodes shows that the temperature coefficient of the barrier height depends on the chemical nature of the metal. This observation is in contradiction with models suggesting Fermi-level pinning at the center of the semiconductor's indirect band gap. From the analysis of epitaxial NiSi2/Si Schottky contacts, we conclude that there is a direct influence of interface crystallography on both the barrier height and its temperature dependence. Finally, we present some new results on the pressure coefficient of barrier heights. Pressure and temperature coefficients of polycrystalline Schottky contacts are correlated similarly to the pressure and temperature coefficients of the band gap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353249
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  • 7
    Electronic Resource
    Electronic Resource
    Low-temperature ohmic Au/Sb contacts to n-type Si (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 994-997 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Au/Sb films annealed at temperatures as low as 370 °C yield ohmic contacts to n-type Si. The contact formation is based on a liquid-phase epitaxy process of Sb-doped Si from Au solution. Measured contact resistivities range around 3×10−2 Ω cm2 and are at least one order of magnitude higher than what is expected from the solid solubility of Sb in Si. The discrepancy stems from local inhomogeneous etching and epitaxial regrowth of the (100)-oriented Si surface by and from the Au solution. Only a small fraction of the macroscopic contact area is doped by Sb and contributes to current transport across the Au/Si(100) interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356425
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  • 8
    Electronic Resource
    Electronic Resource
    Comment on "Negative capacitance at metal-semiconductor interfaces'' [J. Appl. Phys. 68, 2845 (1990)] (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1087-1088 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recently, Wu, Yang, and Evans [J. Appl. Phys. 68, 2845 (1990)] ascribed excess negative and positive capacitances at abrupt Schottky diodes to interface charges and a "waterfall'' of electrons "falling off the Schottky barrier cliff.'' This comment points out that such strange admittances are not related to interface charge at the front Schottky contact but to defective back contacts, as previously demonstrated [Phys. Rev. Lett. 60, 53 (1988) and Mater. Res. Soc. Symp. Proc. 91, 433 (1987)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349677
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  • 9
    Electronic Resource
    Electronic Resource
    Barrier inhomogeneities at Schottky contacts (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1522-1533 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a new analytical potential fluctuations model for the interpretation of current/voltage and capacitance/voltage measurements on spatially inhomogeneous Schottky contacts. A new evaluation schema of current and capacitance barriers permits a quantitative analysis of spatially distributed Schottky barriers. In addition, our analysis shows also that the ideality coefficient n of abrupt Schottky contacts reflects the deformation of the barrier distribution under applied bias; a general temperature dependence for the ideality n is predicted. Our model offers a solution for the so-called T0 problem. Not only our own measurements on PtSi/Si diodes, but also previously published ideality data for Schottky diodes on Si, GaAs, and InP agree with our theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347243
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrathin crystalline silicon solar cells on glass substrates (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 390-392 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We fabricate thin crystalline silicon solar cells with a minority carrier diffusion length of 0.6±0.2 μm by direct high-temperature chemical vapor deposition on glass substrates. This small diffusion length does not allow high cell efficiencies with conventional cell designs. We propose a new cell design that utilizes submicron thin silicon layers to compensate for low minority carrier diffusion lengths. According to theoretical modeling, our design exhibits excellent light trapping properties and allows for 10% efficiency at an optimum cell thickness of 0.4 μm only. This submicron range of cell thicknesses was formerly thought to require direct band gap semiconductors. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118421
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