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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cutaneous pathology 22 (1995), S. 0 
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Erythema infectiosum is known to be caused by human parvovirus B19 and shows characteristic clinical skin manifestations in children, although adult cases of human parvovirus B19 infection do not always show such characteristic features. Recently, we experienced an epidemic adult cases of human parvovirus B19 infection and examined the erythematous skin lesion by immunohistochemistry and electron microscopy to clarify the pathogenesis of the skin manifestations. Light microscopic examination showed slightly irregular-shaped vessels in the dermis. By immunohistochemistry, using anti-human parvovirus B19 monoclonal antibody, positive reactions were found in endothelial cells. No immunoglobulins were found, but C3 deposits were present in the perivascular areas. By electron microscopy, virus particles were found in the cytoplasm of endothelial cells. An inflammatory reaction due to the direct human parvovirus B19 infection in dermal vessels seems to be an important factor in the pathogenesis of the skin manifestations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2940-2945 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the decay processes of the Er:4S3/2 and 4F9/2 states and the mechanisms of frequency upconversion under 800 nm excitation of Er3+ in ternary ZrF4–BaF2–LaF3 glasses. The decay processes of the Er:4S3/2 and 4F9/2 states are discussed on the basis of the Er concentration dependence of the fluorescence lifetime. The quantum efficiencies of emission of the 4S3/2 and 4F9/2 states are 73% and 25%, respectively. The difference in the quantum efficiencies between these states can be explained from the difference in the multiphonon decay rates: the multiphonon decay rate of the 4S3/2 state is much smaller than that of the 4F9/2 state. The multiphonon relaxation is a dominant nonradiative decay process of the 4F9/2 state. A dominant nonradiative decay process of the 4S3/2 state is self-quenching at high Er concentrations. The upconversion mechanisms under 800 nm excitation are also investigated from the dependence of upconversion luminescence on excitation wavelengths (800 and 980 nm), excitation laser power, and Er concentration. The mechanism of upconversion from 800 to 660 nm is mainly due to the energy transfer between the 4I9/2→4I13/2 and 4F9/2←4I11/2 transitions. We also show that the upconversion from 800 to 550 nm is due to excited-state absorption. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method for analyzing the dynamics of domain formation during the thermomagnetic recording process has been developed based on the extraordinary Hall effect. A magnetic domain is written at the center of a cross-shaped magneto-optical sample having an area of 5×5 μm2, and the Hall voltage is monitored during the recording process. As far as domain nucleation is concerned, we find that the temperature gradient around the transition region (i.e., the region whose temperature is between the critical temperature for magnetization reversal and the Curie point) is very important. Under the conditions of high power and short pulse-width laser, a domain can form only during the cooling period. However, it is possible for a domain to form during the heating cycle under a low power, long pulse laser beam. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5938-5940 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical pump-probe experiments were performed in Cd0.9Mn0.1Te/ZnTe multiple quantum wells to study the dynamics of the exciton magnetic polaron in this material. Two transient absorptions of opposite sign were observed. The first signal is negative and indicates the decrease of optical absorption, as the excitons are approaching saturation. The second signal is positive and is interpreted as the absorption of "new excitons" after the initial excitons created by the pump pulse have decayed leaving behind a magnetic polarized Mn environment. The spin relaxation time of the Mn ions has been determined to be 601 ps. Finally, we discuss the effect of the polaron–polaron interaction, relevant in our experiment because we saturate the excitons in the quantum wells. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 3214-3218 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure of the optical phase change memory alloy, silver–vanadium–indium–antimony–tellurium (AVIST), has been investigated by the methods of optical reflectivity change, Raman spectroscopy, and electron diffraction. In order to identify each phase, Sb, AgSb, AgSbTe, and AgInTe films were also studied. The Raman spectrum of an AVIST thin film annealed at 523 K for 1 h in Ar gas, shows two main broad peaks around 116 and 150 cm−1. These peaks appear to be related to Sb vibration modes in the AVIST alloy, but their relative intensities are reversed for the AVIST films in comparison with those for a Sb film. Furthermore, in AVIST, the peak at 116 cm−1 shifts to lower wave number when the vanadium content is increased from 0.4 to 4.7 at %. The electron diffraction pattern of AVIST alloy indicates that the AgSbTe2 crystalline phase dominates rather than Sb. A model of the structure of AVIST consistent with these observations is proposed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 6402-6404 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The wet process for the fabrication of Nd–Fe–B sintered magnets has been developed on the mass production scale. In this process, mineral oil is used as a solvent to prevent the milled powder and green bodies from oxidation. It is removed before sintering. As a result, the oxygen uptake during storage is less than 0.01 wt %/day. By reducing the oxygen content and the total rare earth (TRE) content in sintered magnets to less than 0.2 and 29.3 wt %, respectively, magnets with (BH)max/iHc greater than 50 MGOe/10 kOe, 45 MGOe/15 kOe, and 32 MGOe/32 kOe were obtained with high reliability. The magnets produced by this wet process also show better corrosion resistance and 20% higher mechanical strength than those made by conventional methods. These characteristics may be explained by a smaller grain size, smaller TRE content, and higher density produced by the wet process. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 19-27 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spectroscopic properties of Er3+ in Ga2S3–GeS2–La2S3 glasses are investigated on the basis of the spontaneous emission probabilities calculated by the use of the Judd–Ofelt theory and lifetime data. Frequency upconversion spectra are also measured with excitation at 800 and 980 nm. The spontaneous emission probabilities are much larger than those of the other glass systems such as oxides and fluorides. This is mainly attributed to the large refractive indices of the sulfide glasses. The quantum efficiencies of 4I11/2 and 4F9/2 levels are comparable or larger than the typical values of Er3+ in a fluoride glass. This is a consequence of the large spontaneous emission probabilities and low phonon energies of the sulfide glasses. However, the quantum efficiency of the 4S3/2 level is less than one-half of the value in the fluoride glass. The nonradiative transition probability of the 4S3/2 level is much larger than the value which is evaluated from the multiphonon relaxation theory. This suggests the presence of the other nonradiative relaxation process in addition to the multiphonon relaxation. This process is considered to be the energy transfer from the excited Er3+ to the band-gap excitation of the matrix glass. In upconversion spectra, the 497 nm emission from the 4F7/2 level is observed in addition to the red (665 nm) and the green (533 and 552 nm) emission bands. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 6259-6266 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical absorption and emission properties of Er3+ ions in ZnCl2-based glasses are investigated. The electric dipole line strengths for various transitions were estimated from the measured optical absorption spectra. The spontaneous emission probabilities for various transitions were predicted using the Judd–Ofelt theory. Among Ωt (t=2, 4, 6) phenomenological intensity parameters, the Ω2 value is larger than that measured for ZrF4-based glass. On the contrary, the Ω4 and Ω6 values are comparatively small. Multiphonon relaxation rates follow a so-called "energy-gap law" which is given by WMPR=C exp(−αΔE). The C value is quite smaller than that of the ZrF4-based glass by about two orders of magnitude. This result is attributed to the very low-phonon-energy of the chloride glass matrix. On the other hand, the α value is almost the same as those of other glass hosts. Because of the low-phonon-energy and the host-independent α value, the electron–phonon coupling constant ε of the ZnCl2-based glass is extremely large compared with those of oxide and fluoride glasses. It was also found that several emissions due to transitions between the excited 4 f-levels are detectable, which are hardly observed in other glass hosts. Radiative quantum efficiency is definitively high even for emitting levels of which the energy-gap to the next-lower level is small. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 882-884 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical absorption and multiphonon relaxation have been investigated for Nd3+-doped ZnCl2-based glass. The intensity parameters for radiative transitions of Nd3+ were determined to be Ω2=4.97×10−20 cm2, Ω4=7.39×10−20 cm2 and Ω6=5.12×10−20 cm2. All of the Ωt parameters, especially Ω4, of Nd3+ in the ZnCl2-based glass were large compared with those reported for oxide and fluoride glasses. Multiphonon relaxation rates for three emission levels of Nd3+ were determined from lifetime measurements. The multiphonon relaxation rates in the ZnCl2-based glass were extremely low, because of the low-phonon-energy of the matrix. Values were found to obey the energy-gap law in the same manner as the values in Er3+-doped ZnCl2-based glasses. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2012-2014 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Planar channel waveguides of rare-earth doped fluoride glass are demonstrated with single mode excitation and propagation losses below 3 dB/cm. The waveguide core was fabricated by Ag+–Na+ molten salt ion exchange process in a borosilicate glass (BGG31), and a Nd3+-doped ZBLAN glass was used as a cladding. A 0.45 dB signal amplification at 1.064 μm was observed in the fabricated 1 cm long waveguide, and a 0.9 dB amplification is expected at the emission peak (1.049 μm). Modeling results show 2.5 dB/cm potential gain with the improvement in surface flatness of ZBLAN glass. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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