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  • 1
    Digitale Medien
    Digitale Medien
    Crystallographic and biochemical investigation of the lead(II)-catalyzed hydrolysis of yeast phenylalanine tRNA (1985)
    s.l. : American Chemical Society
    Biochemistry 24 (1985), S. 4785-4801 
    Details
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/bi00339a012
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  • 2
    Digitale Medien
    Digitale Medien
    Pt/Ti/p-InGaAsP nonalloyed ohmic contact formed by rapid thermal processing (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 4319-4323 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Nonalloyed ohmic contacts of Pt/Ti to 5×1018 cm−3 doped p-InGaAsP (λg =1.3 μm) have been fabricated by rapid thermal processing of sputtered and e-gun-deposited metallizations. While the former as-deposited had a rectifying characteristic, the latter showed ohmic behavior prior to any heat treatment, with a specific contact resistance of 4×10−3 Ω cm2. Rapid thermal processing at temperatures higher than 400 °C caused the formation of ohmic contacts for the sputtered metals also, but with the evaporated metals producing slightly lower contact resistance. The lowest specific contact resistance values of 3.6–5.5×10−4 Ω cm2 for evaporated and sputtered metallizations, respectively, were achieved in both cases as a result of heating at 450 °C for 30 s. These heating conditions produced only a limited reaction at the Ti/InGaAsP interface, which was sharper for the e-gun-deposited contact, but had a significant effect on the stresses in the Ti/Pt bilayer. In both the sputtered and electron gun evaporated samples, the stresses were inverted from tensile as-deposited to compressive with values of 2.4×109 and 1.0×109 dyn cm−2, respectively, as a result of the heat treatment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.343291
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  • 3
    Digitale Medien
    Digitale Medien
    Neutron irradiation study of Nd-Fe-B permanent magnets made from melt-spun ribbons (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5305-5307 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Radiation-induced changes in the magnetization of sintered Nd-Fe-B permanent magnets are known to vary widely among specimens produced by different manufacturers. Samples of Nd-Fe-B MAGNEQUENCH magnets, which are made from melt-spun ribbons, have not been studied and show a much reduced sensitivity to neutron irradiation than do sintered Nd-Fe-B magnets. All melt-spun ribbon-based MAGNEQUENCH magnets, i.e., epoxy-bonded, hot-pressed, and die-upset magnets, show essentially the same slow decrease in magnetic remanence with neutron dose. Measurements of the open-circuit remanence Br/Br 0 at various times during the irradiation show a decay of only 1.5% of the preirradiated value for the MAGNEQUENCH magnets after 1 h of irradiation, or a dose of 1.4×1016 neutrons/cm2, compared to a 4.6% drop in remanence for the best sintered Nd-Fe-B magnet (Sumitomo 30H) with the same irradiation dose. Moreover, after 5.3 h of irradiation, the remanence drops by only 3% for the MAGNEQUENCH magnets. Magnets made from melt-spun ribbons are thus the least sensitive to neutron irradiation so far measured for Nd-Fe-B permanent magnets, but are somewhat more sensitive than samarium-cobalt magnets.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.342400
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  • 4
    Digitale Medien
    Digitale Medien
    Radiation-induced changes in magnetic properties of Nd-Fe-B permanent magnets (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3537-3537 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The high remanence and intrinsic coercivity of Nd-Fe-B magnets make them desirable for use in accelerators. Use in a radiation environment requires that the sensitivity of these magnets to radiation be determined and the mechanisms responsible be understood. We present results comparing the relative radiation sensitivity of a number of commercially available Nd-Fe-B magnets. Small samples of these magnets were irradiated to examine the decay of remanence. Our results show that the sensitivity to radiation varies widely among magnets from different vendors, indicating that microstructure and possibly composition play key roles in determining the loss of remanence. We examined optically the microstructure of several of the magnet materials and report on the correlation between microstructure and radiation-induced changes in magnetic properties. Samples were neutron irradiated at the Omega West Reactor in a neutron flux of 4×1012 n/cm2 s at a temperature of 350 K (77 °C). At various time intervals during the irradiation, samples were removed from the reactor and the open-circuit remanence measured. We also measured the quadrant II demagnetization curve of large samples before and after neutron irradiation to monitor changes in remanence and intrinsic coercivity. In general, these samples showed a decrease in the remanence and an increase in the intrinsic coercivity. We also present results comparing the relative decay of remanence for the large cylindrical samples having three different length-to-diameter ratios. This illustrates the effect of the demagnetizing field in determining the rate of remanence decay.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.340734
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  • 5
    Digitale Medien
    Digitale Medien
    1.3-μm integrated external cavity distributed Bragg reflector laser (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 308-310 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The fabrication and performance characteristics of single-wavelength integrated external cavity distributed Bragg reflector lasers are described. The active cavity section of these devices utilize the double-channel planar-buried heterostructure scheme for current confinement. The 4-mm-long lasers have threshold current ∼70 mA and emit near 1.3 μm. The lasers exhibit lower dc chirp than distributed feedback lasers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.339838
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  • 6
    Digitale Medien
    Digitale Medien
    Wide-bandwidth and high-power InGaAsP distributed feedback lasers (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 4640-4644 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The fabrication and performance characteristics of a wide-bandwidth InGaAsP laser diode structure are described. The wide bandwidth is achieved using semi-insulating Fe-doped InP current blocking layers around the active region. The lasers have a bandwidth of 18 GHz at 20 mW, emit 50 mW in a single transverse and longitudinal mode, have rise and fall times of less than 40 ps, have low chirp (FWHM〈1 A(ring)) under modulation, and exhibit harmonic distortion characteristics in agreement with fundamental calculations using a rate equation model. Error-free transmission with no dispersion penalty has been obtained using these lasers in a transmission experiment at 8 Gb/s over 76 km of fiber.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.343820
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  • 7
    Digitale Medien
    Digitale Medien
    1.3-μm InGaAsP distributed feedback laser (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 1811-1814 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The fabrication and performance characteristics of 1.3-μm InGaAsP distributed feedback (DFB) double-channel planar buried heterostructure (DCPBH) laser are reported. The lasers utilize a second-order grating with a periodicity of ∼3800 A(ring) for frequency selective feedback. The lasers have threshold currents in the range 25–35 mA at 30 °C. The lasing mode shifts to longer wavelengths with increasing temperature at 1 A(ring)/°C. The dynamic linewidth under 40-mA current modulation is ∼1 A(ring). The cw linewidth at an output power of 1 mW is ∼90 MHz. A monolithically integrated thermoelectric-controlled laser diode utilizing the DFB-DCPBH laser structure has been fabricated. The emission frequency of the laser can be continuously tuned by ±4 A(ring) using 50-mA controller current.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.336404
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  • 8
    Digitale Medien
    Digitale Medien
    The thermodynamics of ammonium scheelites. III. An analysis of the heat capacity and related data of deuterated ammonium perrhenate ND4ReO4 (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5963-5970 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: An analysis of the heat capacity of deuterated and undeuterated NH4ReO4 has been carried out in which the effects of the anisotropy of the thermal expansion have been considered, an approach hitherto not used for ammonium compounds. In the ammonium scheelites, the axial thermal expansion coefficients are very large, but of opposite sign, and as a result the volume of the scheelite lattice is nearly independent of temperature. It is shown that the correction from constant stress to constant strain results in a major contribution to the heat capacity of this highly anisotropic lattice. The difference between the experimental and calculated values of heat capacity, referred to as ΔCp, is expressed as the sum of the contributions from the anisotropy and the rotational heat capacity. The results of the analysis show that the rotational contribution is much smaller then previously thought. However, the exact contribution of the anisotropy cannot be calculated at this time because the elastic constants are not known. In calculating the heat capacity, maximum use has been made of external optical mode frequencies derived from spectroscopic measurements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.451509
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  • 9
    Digitale Medien
    Digitale Medien
    Erratum: The thermodynamics of ammonium scheelites. III. An analysis of the heat capacity and related data of deuterated ammonium perrhenate ND4ReO4 [J. Chem. Phys. 85, 5963 (1986)] (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 3759-3759 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.452784
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  • 10
    Digitale Medien
    Digitale Medien
    The thermodynamics of perchlorates. I. Heat capacity of ND4ClO4 from 7 to 345 K and the analysis of heat capacities and related data of NH4ClO4 and ND4ClO4 (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 399-407 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The heat capacity of the orthorhombic salt: deuterated ammonium perchlorate, ND4 ClO4 , was measured from 7 to 345 K using adiabatic calorimetry. The heat capacity against temperature curve is smooth, continuous and without anomaly. Values of the standard molar thermodynamic quantities are presented up to 340 K. The heat capacities of ND4 ClO4 and NH4 ClO4 have been analyzed. The contributions to the vibrational heat capacity from the external optical modes of NH+4 or ND+4, ClO−4 and libration from the external modes of ClO−4 along with those of vibration from the internal optical modes of NH+4 or ND+4 and ClO−4, and the acoustic lattice modes for these ions have been calculated. The difference between the experimental and calculated heat capacity, called the residual heat capacity, equals the contribution from ammonium ion rotation and the thermal expansion of the lattice. With recent thermal expansion data, the correction from constant stress to constant strain has been applied and the derived rotational heat capacities of the NH+4 and ND+4 are determined to be in qualitative agreement with those derived from various rotational models.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.457474
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